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[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/186308/edit). Closed 3 years ago. [Improve this question](/posts/186308/edit) In a world similar set in renaissance times, there are natural occurring stones with the ability to produce flames. The more precious the stone, the higher and stronger quality of the flame/fire. Each stone, whether it's low quality or not, can be chiseled by skilled craftsmen to produce more efficient fires. These fire stones can also be re-charged in special fire pits till they disintegrate from over use. These stones are mined and excavated for in remote mountains. Practical use of these stones: If you're in the arctic and need to start a fire, all you need is a few stones and you'll have a blazing fire that lasts longer than firewood. If the stones are of low quality, they can burn for 2-3 hours. If they are superior, they can burn for 2-3 days if left unmolested. The trouble I'm having is **how does one activate such a power**? If it's through spoken word (like a spell), what's stopping someone from lighting a wayfarer's stones on fire with the slip of a word? Would it make sense to inscribe runes into the stone that special individuals can activate? What's a more practical way of summoning and putting out the flames? I'm aiming at having these stones being an every-day-use household item used for cooking, warming hearths, etc. — so the simpler the solution, the better. [Answer] You are basically describing magic coal. It is magic because it can maybe burn longer and stronger, but mostly because it is rechargeable. Other than that it is just coal. You light it up just as non-magical coal, by applying a lot of heat on a small point. You can spin a stick on top of it, or rub two sticks together, or you can bang small rocks to make sparks. On a pinch, you can also use magic to summon fire. The problem with fireballs is that without any fuel their flames run out quickly, but the magic coal solves that problem for the fellow pyro looking for a lasting fix. You can then deactivate it by throwing water, ice, sand, a cloth or someone else on top of it, in order to deprive the flames from oxygen. I don't see why you would want to do that, though. [Answer] ### Blow on it A steady, uniform, 5 second blow will make the stone hotter and hotter until it eventually catches. Just like a coal from an old campfire reigniting when blown on. To deactivate - cool down or cut off oxygen. So cover with sand, water, cloth, etc. This gives them a defined value too - they can't be picked up off the surface by anyone (as they'll ignite in the right winds if a naturally occurring vein is exposed), they must be mined. Which means someone needs to be paid for labour, which means they have a minimum value. [Answer] **Love.** Or what passes as love for the stones. If they touch, they burn. You cannot make fire with just one. If you push them apart, they cool and go out. Or possibly, since they are magic, they go out immediately. [Answer] The fire stones are both spark and fuel but they still need a combustive. They are mined underwater or in caves where every trace of oxygen has been burnt. They are stored in airtight containers and when you want to use them, you just take them out to open air. If you want to store them away for reuse, smother the stone under a wet cloth and put it back in its container quickly. [Answer] The way you describe it, they sound like some sort of fissile material, which emits more heat once the fission is activated, and have short lived byproducts. How does one activate it? Well, just by using a neutron moderator like water, paraffin or graphite. With this you would have heat but no visible flames. Another alternative would be some alkaline metal like sodium or potassium, which are well known for taking fire when in contact with water. [Answer] **Just like a nuclear reactor works (with a bigger safety margin).** Put a lot of them together and they start to make heat. Put them apart and they fade and stop. You may as well handwave two supplemental materials - a reflector (one may put fewer stones inside a reflecting container and they will ignite) and a poison (as in neutron poison - separate them with the poison material and they don't work even when piled together, you have to remove the poison to make them work again). [Answer] If you don't need them to burn more than once between recharging, you could have the energy stored in some kind of phase change. Heating the stones in a special oven causes them to store the energy. Once they are at room temperature, they need some kind of catalyst to start releasing the energy again - which is as simple as touching them with an already "burnt" stone. Stones of different sizes will "burn" for different times, and flatter stones will burn hotter than round stones. Charged vs. burnt states could even be different colors, based on the phase change. A parallel to this in our world are handwarmers based on sodium acetate, or "rechargeable" hand warmers. [Answer] [Sodium acetate](https://en.wikipedia.org/wiki/Sodium_acetate#Heating_pad) used in heating packs is a good example of trigger-based chimical exothermic reaction. With a simple "physical" spark (through a little piece of metal), you will trigger the reaction. So you don't need any complicated way to trigger it (unless you want it fancy or really cool). About your stones, whether they are harvested, mined or built, the reaction should not be triggered easilly, but should instead be "foundable" by human way (by serendipity, basic observation, active research). If collected, the trigger could be very simple but should not be found in the vicinity of the harvesting site. So I think they are a few questions that should be answered before you can focus on a acceptable and plausible trigger : * Are they harvested / mined / built / ....? * If not built, where do you collect them (environnment, temperature, etc.) * Who do build / collect them? For example: * If the stones are found underwater, or collected in the void of space: you could basically used "open air" as the trigger. Then the stones would be stored in a jar, until you empty it and trigger the reaction. * If found in a azot-free environnment (totally fanciful, but it's for the exemple) : a sufficient amount of azot in its immediate vicinity would be the spark. * If built, it could be basically any kind of trigger that would not reproduce outdoors (a rare radiation, an specific radio frequency, a microwave, etc.) Etc. ]
[Question] [ **Could a creature carry its own ecosystem around with it? What traits would it need to make this viable?** These self-sufficient creatures are native to planet which is for the most part frozen and covered with snow with a thin atmosphere that allows a lot of radiation through. These conditions don't allow much plant life to thrive except on a few habitable zones. The planets habitable zones host many native species but are rather restrictive in terms of space. So these creatures which are resistant to the cold environment carry around their ecosystem within their bodies. Due to this they can avoid the intense competition entirely by venturing in the less hospitable environments. **So here are the traits this specific creature needs:** 1 Cold resistance. 2 A means to cope with their poor atmosphere. 3 Adaptations to survive solar radiation. 4 An inner biome to produce food and recycle waste. They are gentle giants (about the size of a polar bear) with a nomadic lifestyle, thus they rarely ever visit the competition filled habitable zones. They lack any sort of natural defense against predators except maybe for their blubber and rely entirely on their hostile environment to keep predators away. They are slow moving, have very long lifespans and can communicate over long distances. They are not very intelligent but occasionally move in herds. Edit: It seems there has been a misunderstanding about the term "self-sufficient". By that I meant an autotroph. A creature carrying around a biome of algae could recycle its waste using solar energy which is abundant on said planet. It is by no means a perpetual motion machine, which is why it uses solar energy and occasionally refills its recourses by visiting the habitable zone. Thank you for understanding. Edit: A means of making up for the square-cub law would be most appreciated as you have done well answering the other aspects on this question. [Answer] Our (distant) ancestors evolved to live in the ocean with particular salinity, nutrients, temperature, etc. To move into more hostile environments, we evolved ways to carry that "perfect" environment with us inside our bodies. For instance, no matter where you go, your body always has the same salinity level as the primordial ocean regardless of how much salt or water you consume (well, if taken to extremes, you die). It's not difficult to imagine creatures that evolved inside a different "perfect" environment doing the same, nor evolving similarly to carry it into even harsher environments than we do. We have examples of your traits 1-3 here on Earth, so that seems settled. Trait 4 is where it gets tricky. From your (edited) description, I think you're describing a photosynthetic symbiote. The problem is that photosynthesis doesn't produce much energy per area compared to how much energy an animal needs just to maintain homeostasis in a hostile environment, much less do anything interesting. For instance, [XKCD](https://what-if.xkcd.com/17/) estimated that a photosynthetic cow could only meet 4% of its energy needs. A big part of that is probably the square-cube law, though, so what if we inverted that to a flat-ish animal with a transparent bubble full of algae on its back? That seems plausible. [Answer] > > Could a creature carry its own ecosystem around with it? > > > Absolutely. As some of the other answers have pointed out, all life on earth currently does exactly this. Your idea takes this to an extreme, but the fundamental theory is well grounded. As for how probable this is, I think that is irrelevant. How probable is it that Eukaryotes incorporated a separate, simple organism (now the mitochondrion) that uses oxygen (toxic!) to produce energy? Of course it's improbable, the very concept of life is improbable. But possible? Very. > > What traits would it need to make this viable? > > > Radiation resistance, as you mention, is definitely important. The radiation resistance could neatly resolve another matter - collecting energy solely through light. Photosynthesis using Terran chloroplasts probably isn't going to cut it in terms of raw energy output. A chloroplast-equivalent that evolved on that planet could very well be able to take advantage of intense radiation levels. With this one adaptation, your creature can solve it's energy and radiation troubles. Temperature resistance adaptations are more easily cited as there are plenty of examples of animals here on earth managing to get along just fine in frigid climates. To further incorporate the inner-biome idea however, consider an internal organism that metabolizes some simple compound very exothermic-ally. Granted this heat is just energy that could have been used elsewhere, but maintaining a stable temperature for the other symbiotes to thrive seems worthwile. For bonus points make the compound a waste product to help solve your recycling issues. Maintaining a stable internal temperature and collecting enough radiation will prove to be a delicate balance. As surface area increases, so does radiation absorption and heat loss. Hair would interfere with radiation absorption, but provide valuable insulation. Your creature would also need some way to collect micronutrients that aren't available as gasses in the atmosphere. Even though plants collect their energy from the sun, they must collect their nutrients from the soil. This might be one of the trickier parts to figure out, but definitely doesn't kill the idea. You may also want to consider how this creature reproduces and what the young look like. Small offspring will struggle to maintain thermal equilibrium and present enough surface area to collect radiation. Large offspring require a considerable energy investment from the parent, but would probably have a better change of not freezing. All in all, awesome creature idea that definitely holds water (and other creatures). [Answer] It doesn’t sound very plausible to me. The problem is that the organism will need to get a supply of energy from somewhere to be able to move and have an active metabolism. Carrying a biome around with you to supply that need might sound like a good idea but it would not be efficient enough. For example an [adult elephant consumes 200-600lb of](http://www.nationalelephantcenter.org/learn/) food a day or at least a ton a week. To grow that amount of food would require a huge area. Even with modern farming methods at say [1-8ton /acre/year](https://ourworldindata.org/crop-yields) would not be nearly enough and an animal with an foot print of an acre would weigh more than an elephant. To make things even harder it’s a cold climate so sunlight is weak and not conducive to mass production of food. The best that could be hoped for would be an organism that hibernated for most of its life and moved very little and very infrequently, but even then I doubt there would be enough energy available to sustain the organism with requirements for growth, some mobility, bodily repair and some basic metabolism. [Answer] I think this question is rather terrestrian. In that it's asking for a lot of stuff for an alien creature that only really makes sense in context of human-like or earth life. And kind of views the world at the level of organism. First off, life forms are themselves carrying around their own biome. Like all of them, it's kind of what a multicellular lifeform is. It's a lot of different cells that work together in important and cooperative ways. I cannot digest most the things I eat but there's a bunch of stuff in my gut that can turn that into things. Also, my body heats itself up because that's the chemistry runs faster in the warmth, a lot of that chemistry is done by mitochondria which is a different critter than my cells are, or I am. So note, everything you're asking for is perfectly reasonable and to some degree stuff that life does well. We live in an atmosphere that is one filled with oxygen, one of the most corrosive substances known as communities of cells, and in cooperation with bacteria etc. And things live in habitable zones. That's why those zones are habitable, things live in them. Extremophiles are often more the rule than the exception. Life is quirky like that. The only thing you need is energy. You have a bear sized creature that is lives a nomadic lifestyle. It needs energy to perform this movement. And generally it will tend to need a reason to be nomadic. Animals don't waste energy going places if they make their own food. Trees are not known for being the quickest creatures on the planet, in part because they make their own energy. But, while some trees are bear sized, they are absolutely not nomadic. They move a bit towards the sunlight but it's certainly not very fast. Bears can easily gobble up 20,000 calories a day, sometimes as much as 100,000 when the energy is plentiful and then hibernate when it gets cold. So what exactly on your planet provides this massive amount of energy, in some particular place, that these animals must go to in order to survive? And if there's a bunch of energy out in the snow, why aren't there other creatures that eat it? You could certainly make them basically as large as bears and active as rocks sucking down the energy of the space radiation, because they live in a communal relationship with some crystal fungus but that's not really nomadic. Or you could make them kinda active like bears but then they need the alien equivalent of scarfing down a whole crap-ton of fish, or a consistent diet of some other energy source calories a day, which then wouldn't really require the nomatic part of it. They could very much graze some kind of radiation consuming moss like stuff for energy, or rather take it with them in some fashion. But, there'd be some reason the radiation consuming moss would need to get around on a bear like creature. Plants, because they make their own food aren't the most cooperative of species. You might be able to get 3000 calories a day from intense space radiation, but that amount would certainly warm the place up pretty significantly, if it had to fall on the surface of a bear. Is there something else, like methane snow a bunch of oxygen around? If you have chemicals that can release a lot of energy together, you could certainly have some biome help with the conversion to usable energy. --Edited to add: 1 Cold resistance. - This isn't a thing. If you live optimally at these temperatures they aren't cold for you as an organism. We like the temperatures our bodies maintain because our chemical reactions go well at those temperatures. 2 A means to cope with their poor atmosphere. -- This isn't a thing. If you live with a thin atmosphere then this would be poor for humans, since we need to breathe oxygen and don't do well with solar radiation, but if you didn't evolve for that then it's not something that matters. 3 Adaptations to survive solar radiation. -- This is a slight thing. In theory high energy stuff can break complex things but oxygen is one of the worst and most destructive things and we breathe it like a boss. And this sounds like a lot of nummy nummy energy. 4 An inner biome to produce food and recycle waste -- All bodies are doing this. That's life's jam. If it's something you can recycle bodies do this. The producing food is a problem. Since you still have to obey the laws of thermodynamics. You could make it hibernate for like 25 years when the radiation absorbing moss covering its body builds up enough energy reserves to power its bear to the spawning grounds, and all the bear/moss cooperative critters go and have bear babies and moss babies. Or have some additional energy around. Maybe the radiation absorbing moss stuff is optimally adapted for the pole, and can't breed that far south, and only by riding a bear-like creature south and then north could it get successful. Calling something inhospitable is just wrong without context, things only need energy, beyond that life finds a way. Nothing else from the planet lives there because nothing else can really harvest the energy (whatever energy is has). But, if stuff lives there it's both hospitable and habitable. Things like radiation and heat and cold and atmospheric pressure seem inhospitable because we, as humans, can't live there. An alien that lived there would have no issue at all. Ps. I used moss as a shorthand for the only radiotrophic stuff I know about from Earth. That went and very quickly took extreme radiation of a nuclear meltdown and turned it into energy. Because, again, these aren't problems. Extreme radiation like that isn't a problem, it's a food source. [Radiotrophic\_fungus](https://en.wikipedia.org/wiki/Radiotrophic_fungus) [Answer] I'll divide the answer in two, first how something similar can live on a smaller scale and then where can it take the additional energy to scale up. # Living on smaller scale ## Lichens I'll first introduce some characteristics of lichens: * They are composite organisms that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. Each of the two provides what the other needs. <https://en.wikipedia.org/wiki/Lichen> * "is generally self-reliant in feeding itself through photosynthesis in the algal cells", but while they do live in dry environments they still require some levels of moisture. Otherwise they dry up completely and stop living until the moisture returns. <https://web.archive.org/web/20191111233123/http://www.ucmp.berkeley.edu/fungi/lichens/lichenlh.html> * They live in the most extreme environments on earth, including the arctic tundra. * Some of its species were able to adapt to live on a simulated martian surface for 34 days and survived 15 days of actual outer space (It's not clear if living or regaining life afterwards) <https://web.archive.org/web/20120528145425/http://www.skymania.com/wp/2012/04/lichen-survives-harsh-martian-setting.html/> and <http://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/Lichen_survives_in_space> * Its ability to withstand pollution depend on how much energy the photobiont gives the mycobiont. In particular it dies when the photobiont requires too much energy to fix its cell structure and has none left for the mycobiont. This means that in case of no pollution it has additional energy usable for other things. A scale down may allow us to use the square-cube law to our own advantage. Not to mention that them being slowly moving helps us a bit. * Have a long lifespan. The oldest has 8,600 years and is the oldest living organism. ## Problems of lichens The first potential problem is the cold, in case that planet is colder than the arctic tundra or in case the changes require this kind of compensation. There are various methods to survive in colder environments, among which antifreeze proteins <https://en.wikipedia.org/wiki/Antifreeze_protein> for up to -30°C and other substances like <https://en.wikipedia.org/wiki/Xylomannan> for up to -60°C. Freeze tolerance doesn't seem to be suitable in a planet covered in snow. It'd just stay frozen. The second problem would be the inability to move, for which I think there are two two possible ways: * just have the fungus move. The answer to this question [Biology of mushroom creatures](https://worldbuilding.stackexchange.com/questions/161989/biology-of-mushroom-creatures) says that it's possible and it seem they'd be able to have the behaviors you ask, just not that big due to how it gets its energy (As per eventual additional energy required, it could use the additional energy mentioned above). * Alternatively having the mycobiont being a sufficiently small animal instead of a fungus. The last one is that they take their energy from their surface which exposes them to the square-cube law as by increasing the size, the surface increases like a square while the total cells and the energy they need grows like a cube (unless you have something flat, which wouldn't be much like a polar bear). # Additional energy ## Cold fusion The missing part is the energy to allow it to scale up to the size of a polar bear. My suggestion is cold nuclear fusion. I know that as a topic it's not well received by most scientists, but even if marginalized there are still various scientists that are currently researching on it (for example this conference in 2019 <https://iscmns.org/iccf22/program/> ) including university professors <https://en.wikipedia.org/wiki/Yoshiaki_Arata> (around 2008) and there are some known ways that could theoretically make it possible <https://en.wikipedia.org/wiki/Muon-catalyzed_fusion> . I hope that the presence of theoretical possibility is enough as the question wasn't tagged with 'hard-science'. Nuclear fusion could be powered with just deuterium, which could be taken in large doses from sea water from the habitable zones. Than the organism could use the energy it still retain from the previews time to process the water. At first it could reduce the amount of normal water with something with the same result to what done industrially ( <https://en.wikipedia.org/wiki/Girdler_sulfide_process> followed by distillation). This is made even more plausible because the required amount of water processed every day would be 68 mL. ## Frequency of eating The energy needed for a polar bear is the equivalent of 2Kg of fat/day <https://kidzfeed.com/what-do-polar-bears-eat/> or around 74MJ/day. But this could be much lower as this creature wouldn't need to move as much as a polar bear (if anything it doesn't hunt). Applying the same ratio from active to sedentary as humans <https://health.gov/dietaryguidelines/2015/guidelines/appendix-2/> the resulting estimation is 60MJ/day. A polar bear can take a meal of 50 kilograms. Drinking 50Kg of sea water could be refined in that way to 0.5Kg by removing the non heavy water. In <https://en.wikipedia.org/wiki/Heavy_water#Toxicity_in_humans> it says that the ratio is 1.1 g deuterium / 32 Kg normal water. This means 1.7 g of deuterium. From <https://en.wikipedia.org/wiki/Nuclear_fusion#Neutronicity,_confinement_requirement,_and_power_density> it seems that hot deuterium fusion has a specific energy of about 225 million MJ per kilogram of deuterium. If the hypothetical cold fusion is able to make the organism use 20% of this energy, than it would have 225000 MJ/g \* 1.7g \* 20% = 76500 MJ. By dividing this by the requirement of 60MJ/day would give us 1275 days or 3 years and half. From this we must subtract the energy needed to refine the sea water and prepare the deuterium and based on my understanding this should be a fraction of what a nuclear fusion would produce. But even giving it half the energy this animal should still be able to survive while visiting the habitable zones only once every two years, which I guess is within what asked. The remaining problem would be the generation of neutrons and protons, which I guess could be solved by using the same characteristic as <https://en.wikipedia.org/wiki/Deinococcus_radiodurans> or other internal protections. # Conclusion The resulting being would need to have some of the properties of lichens, namely the ability to survive out of thin air, but it would need to be able to move and have the size of a polar bear. Additionally for some strange evolution path and coincidences (akin to when life started) it was able to develop the complex machinery and chemical reactions to allow the cold nuclear fusion to happen. If my estimation are right this organism would need to return to the habitable zones only one day every two years. Additionally the amount of water that it needs to drink each time would justify its size even if the rest of the time it lives in a mostly desert place. Edit: added cold fusion as energy source and adapted the rest to it. Additionally I fixed the readability of the part about the cold. [Answer] # Energy As others have noted, your big problem is energy. If your surface is cold enough to have a polar climate, then it seems likely that the planet does not receive sufficient irradiation to maintain a large autotrophic animal. However, there are some caveats: * A thin atmosphere without significant greenhouse gases + a high albedo surface could allow for significant irradiation + low surface temp * Even though Venus is much closer to the sun than Earth, the surface temp would be about [-40 C](http://www.realclimate.org/index.php/archives/2006/04/lessons-from-venus/) if it didn't have any greenhouse gases! * Problem: water vapor is both high albedo and a greenhouse gas :/ On the other hand, it doesn't *drive* climate, but rather *responds* to it There are a couple scenarios I can think of that might power enough handwavium to get you to your goal. At any rate, you should give up on the polar bear body plan in favor of a large, flat creature, like a land-based manta ray. It would ideally be black, because it's absorbing as much radiation as possible, including UV! Think "2-D snake" that moves via gentle undulations that travel across its surface. # Cloud City The trick is that you want enough clouds to keep the surface below freezing most of the time (or you don't have much of a polar biome), but not so many that your creature starves to death. Instead of flat, uniform cirrus clouds, you want billowy cumulus which are very patchy/clustered and create large spots of cold darkness over the land they pass. A nice feature of such clouds is that they pose an environmental hazard for your creatures. When a cloud passes over them, they either have to burn stored energy reserves, or rest and go into a quiescent state until they get the warming rays of their star again. The clouds, as mentioned before, conveniently reflect a lot of solar radiation before it hits the surface, preventing the surface from heating up despite high average radiation flux at the planet's orbital distance. But you want just enough clouds to keep the temps freezing, but not deathly cold freezing (ideal average surface temp closer to -10 C rather than -50 C). And they need to be sparse enough that your plantimals can feed regularly. # Tidal Lock Another idea which can be used separately or together with Cloud City is the idea that the planet is nearly tidally locked with its star. So there are, say, 4 "days" per "year". If it were tidally locked, it would be 1 day == 1 year. With the slow rotation, you have half the planet frozen on the dark side, with the other half balmy on the warm side. Near the terminator (dawn side), you have ice coming into the sun. Obviously, the autotrophs wouldn't venture onto the night side, because that is a desert for them, and certain death (without major stored reserves). But perhaps the polar region persists for quite some time before "thawing out", so you have a nice temperature gradient from freezing-cold to tropical-UV-burnout across the day side. # Axis of Winter Also, a more extreme axial tilt would also facilitate more extreme winter/summer variation. So maybe it isn't polar conditions all year round, but only most of it. The amount of winter you have and its variation can be controlled by the day length and the axial tilt. Extreme tilt will give extreme seasonal variation, while long days will bring more stability within each longitude. You can tweak these to control the weather on your world. Freezing cold all day every day is probably too much for a walking plant. But even bears hibernate! Your snowmat could do something similar, foraging during spring through fall and going dormant during winter. # Nutrition While your creatures can get carbon from the air via CO2 (though presumably this is very rare in your atmosphere) and can fix its own nitrogen using symbionts, it will still need to replace elements like iron, phosphorus, sulfur, and lots of trace metals. If the continents are constantly being subjected to freezing/thawing conditions, then you can just say that they sometimes "graze" on exposed soils containing vital nutrients, and absorb them that way. They can also feed on microbes and [worms](https://www.usgs.gov/faqs/do-ice-worms-exist?qt-news_science_products=0#qt-news_science_products) in both the soil and the ice. I don't think the density of worms/algae is high enough to support a mobile animal, so it will only feed on these to replace essential minerals, relying on its chloroplasts for primary energy. # Ultraviolet While earth does not receive enough solar energy to support autotrophic animals, your planet might. Most of the plants and creatures on the surface use dark pigments to protect them from radiation damage to their DNA, but your walking plant may actually harness UV photosynthetically via [scintillation](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2776492/). Now, coral don't actually harness the reflected yellow light because they are hunters, not plants. And unfortunately, [chlorophyll](http://www.webexhibits.org/causesofcolor/7A.html) is specialized to absorb blue and red light, not green-yellow. On the other hand, both red and blue-green [algae](https://algaeresearchsupply.com/pages/lighting-for-algae-cultures) are specialized to absorb yellow and green light. If your creature carries a mix of all of these, it can literally harness the full visible spectrum (though not at 100% efficiency). Some researchers believe that land plants are green exactly because cyanobacteria were the first autotrophs and occupied the green-yellow niche, and that chlorophyll was invented by bacteria that were forced to feed on "greenless" sunlight. While animals use melanin to absorb UV and reduce radiation damage to DNA, this UV energy otherwise goes to waste. It is probably better for your creatures to use the "coral skeleton" trick to down-convert the UV into visible light. You obviously can't rely on a normal endoskeleton for this. You would want something more like a semi-hard shell, or at least lots of little bony plates near the surface of the skin to act as "UV reflectors" for your creature. Good luck! ]
[Question] [ [![Smaug giganteus ](https://i.stack.imgur.com/ac716.jpg)](https://i.stack.imgur.com/ac716.jpg) A *Smaug giganteus*. If you do as much as think about slaying it, I'll force feed you gasoline and shove a match down your throat. Sungazers are awesome. They're so awesome I decided to base some parts of my dragons' appearance on them. Dragons in my setting are hexapodal, roughly horse-sized, omnivorous creatures with human intelligence, maybe at around 300-400 kg in weight. They use unlikely, but biologically synthesizable materials like graphene in their body. The setting has guns and (wannabe) dragon slayers, but magic will take care of those for now. I despise spiked armor (but in all honesty, it looks cute on sungazers), but I want to keep it for now. I want to feel better about my decision, so I need an excuse. This excuse should be a practical advantage that spiked (natural) armor grants. Being a way to attract mates is an aesthetic reason, so it won't cut it. **What would be the most important practical advantage spiked (natural) armor could grant for dragons?** [Answer] The most obvious reason for retaining the spikey look is the fact that the spikes are not scales but scutes. Although developed from the same squamous exodermis cells a scute or osteoderm is very different from a scale. While scales can be shed regularly to allow for growth, scutes may have continuous growth from a lower level of vascularity within the body, and if not ablated by wear or maintenance, may naturally become larger, as with alligators & crocodiles, or in the case of the Sungazer, horned lizards, horned toads and others, may grow long and spikey. Do to additional vascularity within the scute it may be used to regulate body temperature as well. Your solution is self evident. [Answer] The spikes on your little sungazer seem to be arranged to discourage attacks from behind. To grab the (usually) vulnerable neck from behind, an attacker would have to rake his (always) vulnerable belly across those very jagged spinal scales. This could also be used to dissuade unwelcome sexual advances which human-intelligent female dragons would find very useful. [Answer] Reasons for "spikes" in dragons: * Temperature regulation. Being able to move those in different angles to the sun, and "vent" heat is one reason. * Sexual prowress/sexual selection, which you are already allowing for. * Water collection. [As in the thorny devil of Australia](https://www.smithsonianmag.com/science-nature/spiky-lizard-drinks-sand-its-skin-180961002/), the Texas horned lizard in North America and Horvath's toad-headed agama in Turkey--all are spikey, all use that as a mechanism to channel precious water onto their skin, and thorny devils actually "drink" using their skin, sometimes even by burrowing through dew-laden sand. * Predator protection. While it might not be a thing for the older, larger dragons, it might have been good for the smaller ones, or it even could be an artifact of earlier evolution from when they were smaller. Since then, it's been chosen as a trait because of natural sexual selection attractiveness. * For flight control. The spikes can be retracted somewhat and also used to steer or slow flight, similar to the way aircraft use flaps. Since they have so many, that might mean finer control. In fact, I would say that it could be ALL of these things rather than just one.. [Answer] **Gigantic Snakes** And I mean *large* ones, big enough to eat a horse and dragons the size of a horse. (Which actually exist in certain parts of the world. I'd show a picture, except a snake eating a deer and/or alligators is somewhat graphic.) In a setting with graphene-enhanced dragons, it stands to reason that there'd be graphene-enhanced snakes. And these snakes would love to hunt dragons. So the dragons did what prey does - they evolved. Generations of dragons with gradually sharper scales led way to the construction of spikes from the scales. Thus, when a giant snakes come slithering along to eat the modern-day dragon, the dragon merely allows itself to be caught and the snake gets ripped to shreds on the dragon's spikes when the snake starts squeezing. [Answer] When they are crawling through their dragon holes underground, the spikes keep them from falling down backwards when heading towards the surface. [Answer] **Hollow Spikes** Polar bears have transparent and hollow fur which scatter light, which is why they look white... <https://www.earthrangers.com/wildwire/risk/polar-bears-have-clear-hair-so-why-do-they-look-white/> What if the spikes of your dragon work the same way... Add a bit of magical ability so that your dragon has the ability to manipulate the transparency and width of spikes...it can change color :)... Camouflage ability acquired.. Which can then be used as an offensive attack ability and a defensive mechanism. Add in all the advantages listed by all other answers ... [Answer] Spiked armour is normally considered silly because instead of deflecting a sword, it will catch it (despite looking cool). The same doesn't hold true for dragons, which evolved before swords; most would-be predators of a dragon will be attacking with natural weapons (claws, teeth), and if those weapons are not long enough then softer parts of the attacker can easily be caught on spikes, making it vulnerable to counter-attack. Another advantage is that a spike can be damaged and simply break off, which will not cause a great deal of harm to the rest of the dragon - it can "take a hit" for the softer body underneath. I'd expect this to be an advantage against guns, too (the different angles everywhere will make it difficult to get a shot that won't ricochet off the dragon), but that probably wasn't a factor in how the spikes got there in the first place. [Answer] This is a [Diodon holocanthus](https://en.wikipedia.org/wiki/Long-spine_porcupinefish). Notice the spikes. ![A.K.A. long spined porcupinefish](https://i.stack.imgur.com/bH3Ep.jpg) It is a very cute critter but only until it feels threatened. This is the same beast when it goes hulk-mad: ![COME AT ME BRO!](https://i.stack.imgur.com/7GrTM.jpg) --- Your dragons are the same. When angry or scared or fighting for territory or when in heat they become round and many times larger, and the spikes point out. No other creature with more than a couple neurons will have enough courage to come anywhere close to such magnificent balls of spiky death. ]
[Question] [ **Closed**. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers. --- **Want to improve this question?** Update the question so it focuses on one problem only by [editing this post](/posts/109661/edit). Closed 5 years ago. [Improve this question](/posts/109661/edit) I need to house 50,000 people but I only have a 2.7 hectares (126m by 213m). Just like [Kowloon Walled City](https://www.scmp.com/sites/default/files/2013/03/16/scm_news_1.1.nws_backart1_1_0.jpg). However, the land is currently empty and I can *plan* for that many people before they all arrive. I don't want to build a prison, but I equally don't want the city to become a crime den. Instead, I hope to build a functioning liberal democracy that people want to stay in. My city state would be an independent nation in contemporary Europe. The borders are guarded with passports required to travel in or out. The neighbors are friendly and willing to engage in trade agreements. What planning can I do before my citizens arrive to avoid the problems Kowloon had? Can that many people live freely in such a small area? [Answer] First what you need to plan is sewage system. Nothing forces you to become violent criminal like living in excrement. The system should be capacious to such extent that turning off part of it for service wouldn't affect any part of building. Second things is designing the ziggurat in such way that the building doesn't reflect social division. So poor people at the bottom, rich at the top. Looking at photos of Kowloon you can see that bottom could have gardens or some sort of green. Then at some point, you could make glass floors that would let light into the center of building again making flats above and below such divide more attractive and, of course, pricy. Third - discreet police. You need to have police on site so there wouldn't be situations like in Dredd movie. At the same time, the visible police cannot be perceived as a threat or suspicion toward the citizens. So something like Hong Kong Police (note that my knowledge of HK police come from Wikipedia, HK police dramas and Sleeping Dogs game) a grunt force that serve more like a security, paramedics, firefighter-taking-cats-out-of-trees type of service. Fourth - time to get out of such building and escaping to forests, parks etc. What would be attractive to live inside such building is time it take to just close the doors, get to an elevator and call it a day. So maybe not building wide roads and multilevel parking space but rather creating trams, metro and trains stations below and in the middle of building to quickly move to suburbs or outskirts [Answer] The thing with Kowloon Walled City was not the denseness, it was that there was nobody enforcing the rule of law. It was basically an abandoned area where the monopoly on violence was ceded to the organized crime gangs. Just make sure you have a police force and preferably a small standing army that is separated from the police. Be strict on corruption. Provide fundamental human rights, such as healthcare and social securities (if you're American these may or may not register as fundamental human rights, but in most European countries it's not up for debate and lacking them will make people leave if they can and you end up having to force them to stay at gunpoint). Also, there needs to be an incentive to live so densely packed. Preferably you have a highly thriving economy. Moving to your state will be a betterment of life for the inhabitants. They will be better paid and have nicer (if somewhat smaller) apartments than if they lived in the surrounding country/countries. Child care and hospital care will be better. If those things are in place, the walls will have to be to keep people out, not in... Edit: **SZCZERZO KŁY** Is right, a well functioning sewage system should not be overlooked. Also, of course, as some might point out good opportunities for sunlight and recreation is important to the well being of your citizens. Utilizing the rooftops as terraces is a good step, but being able to reserve some of the ground space to use for a park is a good investment in quality of life. [Answer] The problem that Kowloon had and one of the few things that apparently were actually enforced, was a height restriction due to the proximity to a nearby airport, limiting the buildings to 13 or 14 floors. If you do not have that, then simply build up. The [tallest residential skyscrapers](https://en.wikipedia.org/wiki/List_of_tallest_residential_buildings) have close to 100 floors, which would give you several times the living space. And this is more of an economic than a technical limit. If you look around a bit, you will find a lot of architects dreaming about constructing whole cities in a single tall building. For example a proposal like [Sky city 1000](https://en.wikipedia.org/wiki/Sky_City_1000) is a bit to wide at the bottom but has nearly the required population density at a comfortable level. Apart from this, you should ask yourself why people would want to live in your country? After all it will be cramped and extremely expensive, as you have to basically import everything. There also won't be much available (legal) work, apart from maintenance as it would be far cheaper to build offices and factories elsewhere. Probably the only good option is to turn it into a tax haven. This of course directly leads to an existing example, namely [Monaco](https://en.wikipedia.org/wiki/Monaco). This densely populated city state officially is home to a lot of rich people who can afford a small apartment there. Of course most of the year they are on "working holiday" in their "secondary homes" somewhere nicer. So the official population density might sound worse than it actually is. Note however, that this will anger your neighbours. While they might generally be inclined to trade, they will still want to gain something from it. Just taking their tax income for a few meager exports will get you isolated and embargoed in no time. After all you are dependent on imports, so a potential blockade will starve you into submission extremely fast. [Answer] # Take a cue from modern high density buildings [![enter image description here](https://i.stack.imgur.com/6JB7z.jpg)](https://i.stack.imgur.com/6JB7z.jpg) These are the Galaxy Towers in Gutenburg, NJ. Each of the towers is 44 stores, and has ~1000 people living in them. Of course, that is at the relatively low spatial density of the modern US; each tower has around 300 apartments with roughly 3 people per apartment. Even at this relatively comfortable amount of space, the towers are pretty good at conserving land area. Each tower is about 40m by 40m on the base. The three towers are about half a hectare. Now half the size of each apartment, cram six people into each apartment, and put up six towers in your ~3 hectares of ground area and you have hit your desired density. So if you really want to get that density, you are looking at buildings of ~50 stories, lots of very small apartments, probably shared communal bathrooms, and people who can tolerate living six to a bedroom. Otherwise, construction would probably proceed just like a modern high-rise residential complex. [Answer] I'm going a slightly different direction than the other answers here: Kowloon already shows us that it was technologically possible years ago, so I'm not going to focus on what technology is there so much as how your specific scenario came to be. ## The Trading Outpost that grew up You want a limited amount of space, but willingness to trade . . . this sounds to me like it started as a trading outpost. ## An example of how this could occur: In its early days, the outpost was a small territory near the trade routes of several powerful nations that were constantly warring with each other, but any 2 could easily defeat one of the others. Because the territory was so small, and had cost so many lives, the larger nations mutually agreed to its independence. After some time, this independence meant that even citizens of nations at war with each other could do trade here, and this caused a small merchant class to grow into a wealthy merchant class. Over the years, these merchants built up the natural trade routes to be much better than the surrounding trading options, causing more money to flow through their tiny land, attracting more and more people until eventually they had an enormous population relative to their land mass. ## Reasons for the small territory: Mountain pass: The mountains severely restrict the size of the territory, but since multiple mountain passes cross here, people built it up. Island: A remote island nearly equidistant to several world powers. The island was a natural place for a trade outpost Pirates: People like to prey on trade, so trade was restricted to small easily defensible positions. Dangerous animals: Lions and Elephants are in the territory surrounding this oasis, causing people to stay close together. Zombies: You never said this had to be **completely** realistic! ## Explicit Answers to the question Avoiding crime: Wealthy merchants have a strong motivation to encourage trade and prevent crime. Their private police forces would naturally be very unobtrusive, yet quick to react to problems . . . or they would be out of jobs! Avoiding social unrest: Many wealthy merchants live in the same area, but can't expand too terribly much because there simply isn't the room. They will find ways to be a bit showy about their wealth. (Perhaps decorating their homes with gold or jewels.) (Un)Fortunately (depending on your perspective) there isn't the room to block off roads for the wealthy or powerful, so any person can easily run into anyone else. Therefore politeness and generosity to everyone is probably a trait of this community. Logistics: This may be a cop out, but . . . A wealthy society that has had years to work out how to handle food, drink and waste processing has indubitably come up with various solutions to this that are far better than I can in a few minutes. :) We know that Kowloon was able to do it on a shoestring budget. Wealthy merchants can definitely accomplish this on their budgets. I would imagine the interior of this territory feels more like a bustling mall than anything else you would quickly think of. [Answer] You need social life, like sports clubs, masonic lodges and churches. Tocqueville, in the Democracy In America, noted that most americans were part of some kind of organization, of brotherhoods, and learned politics in these institutions (and that's maybe why America has or had a healthy political system unlike latin america or France, both plagued by coups and revolts). About religion - it can unite or it can divide and the state security in your arcology will have to supress the religious leaders that bring division, no matter their religion while at the same time allowing for religious expression that does not hurt other people from different religions. Using islam as example: your state security should allow the traditional dresses, food restriction, respect the right of not working fridays while supressing those that talk too much about jihad. The institutions like the freemasonry and rotary club also act as shock absorbers between the citzen and the hand of the state, that can be quite heavy even in a democracy, giving their members means to act in the political body and a sense of belonging. [Answer] ## Go up 50 storeys Kai Tak Airport is gone, so no need to limit height. Assuming you lose 25% of space to infrastructure, you now have 101.25 hectares or 10.9 million square feet (1.01 million square meters). 25% is probably less than most commercial developments today, but you have a much more compelling need to design for space efficiency. Given 50,000 people, that's 218sq.ft. (20.3 sq.m.) per person. For a singleton that's a fairly respectable "Tiny house". Many "coliving spaces" are tighter than that, with living and kitchen space being in commons areas. A family of 4 gets 872sf (81.2sm), lush by comparison to 1920-era standalone houses built for working class families. ]
[Question] [ Assuming that * the planet is 20 light years away (so back and forth trips would be impractical) * we have no clue whether there is any edible life forms on the new planet * hibernation (freezing/thawing etc.) of our bodies isn't invented * we carry 100 people * The ship can travel up to 1/2 the speed of light I know that in order to maintain a good gene pool, we will need at least 100 healthy people, who may grow old during the journey and have their kids (extra mouths to feed) to keep the generations going. Even if it is high energy food, people need to eat a lot and drink a lot. About how much would any space colonists need to bring? Would we need to balance between space craft fuel and food for the crew? [Answer] If the average person had 2kg of food a day, and 1 liter of water, you'd need about 2,922,000kg of food and 1,461,000L of water for the trip. Not feasible on a spaceship, which has to conserve space and weight. Rather, what you need are renewable supplies of nutrients and water. For drinking water, <http://mentalfloss.com/article/67854/how-do-astronauts-get-drinking-water-iss> and for food <https://en.wikipedia.org/wiki/Cellular_agriculture> the matter for this food would have to come from recycled waste, so the supply of food would have to last longer than the time it takes to break down human waste into parts that can be used to regrow the cell cultures. Water is a bit funnier since it's used for so many different purposes, but you'd always need a supply of it in store while recycling used water. A good thing to keep in mind is that everything in space travel triple and quadruple redundancy, so much can and often does go wrong, that your backup plans need a last resort emergency plan, which has backups. [Answer] [Using this](https://worldbuilding.stackexchange.com/questions/9582/how-many-people-can-you-feed-per-square-kilometer-of-farmland/9601#9601) as a reference: One km^3 of aeroponics bays can feed can potentially feed 49,210,000 people on sweet potatoes at 2k calories per person per day, from there its simple mathematics. Still using my reference, we multiply that number by 54/70 to get from sweet potatoes to potatoes (which contain all the nutrients you need in a healthy diet), to get to 37,962,000 people fed by 1 km^3 of aeroponics bays, from there we divide down the area we need to feed 200 people (assuming a huge redundancy because this is space), then multiply that by 37,962,000/200 to get 189810, then take 1/189810 km^3 in m^3 to get 5268.43m^3 of ship space needed to feed your crew of 100 people. Additional problems: you need to have a huge supply of vitamins and supplements in case someone has a dietrey problem and ends up requiring some. Also you are going to need to coat your ship in solar panels to be able to power these aeroponics bays. Also i'm not quite sure on how to work out how much water you are going to need, but it has to be a continuous process (like BSG), else you may have shortages. The final problem is you have to have a ship vaguely similar in design to that seein in The Martian, as you need to keep these people in an environment where they can experience gravity and do exercise, else their muscles will waste away into nothing and you will enver be able to land [Answer] As usual, Star Trek got it right. You can't carry enough food, so you need a replicator. You need a machine which can take human waste (both solid and liquid), break it down into its component chemicals and minerals, add a little energy from the ship's fusion reactors and somehow reconstitute it into something that humans can digest. It doesn't need to have openings into each crew member's quarters (like the ones on the Enterprise) but it needs to perform that basic function efficiently and reliably. Now comes the tough part... you need to recycle your crew. There is a limited amount of biological materials on-board and at some point in the journey, somebody is going to get pregnant. Where will the material for the new baby come from? You either need to carry extra biomass in storage (which is only a short term solution) or you need to somehow culturally link the birth and death process. For an expecting mother to get the extra food she needs to build a new person and for that person to get the extra food needed to grow and mature... somebody will have to die. Closed loop systems are not for the faint of heart. [Answer] You cannot simply pack food for a 40 years travel and some years to settle on the planet. You will need to grow food on your ship, mostly plants. You will not bring along livestock, they require too many resources. You will better use bugs and insects for protein supply: they grow fast and in large number. [Answer] Hmmm... I'm gonna keep this answer short because it's late on my end, but I guess the two big things I have to say is that firstly, you wouldn't need to bring much "food" at all (at least not in the way I think you mean it), and secondly, as an incidental bit of constructive criticism, 100 is hardly adequate for long-term colonization. I'll get to the food in a second, but if you want a truly sustainable population that'll last long enough to establish a permanent human presence on your planet without the need to bring in any new people a few generations down the line, you'll need a few thousand people. 20,000 to 40,000 is usually a good number, while 100 is only suitable for establishing small colonies you intend to use only as temporary scientific/mining outposts or that you plan on sending more people to in the future. Basically, a colony of a few hundred is only feasible for in-system settlement where you can expect frequent communication with Earth and a steady influx of new people as they become needed. Interstellar or intergalactic colonization requires large numbers. As for food, there are a number of great videos on Isaac Arthur's Youtube channel explaining the basics of interplanetary and interstellar colonization, including your desired population size, multiple methods of getting people there, the likely design of your colony ship (if you're sticking to known physics), and most importantly, food and living space aboard your ship. Here's a hint: it involves genetic engineering and tofu-burgers. Here's a link to the most relevant video. There should be links to others included in it, but I'd also recommend watching the Terraforming, Bioforming, and Interstellar Travel Challenges videos, as well as the other Life in a Space Colony videos: <https://m.youtube.com/watch?list=PLIIOUpOge0Lvr26RCeM_6mq72KFhPWEkG&v=THqtAQOicQI> Hopefully this'll help! ]
[Question] [ **This Query is part of the Worldbuilding [Resources Article](https://worldbuilding.stackexchange.com/questions/143606/a-list-of-worldbuilding-resources).** --- I've never tried building a world before. That is, I haven't tried to put it on paper. At most, it's just day dreaming. **Is there a generally accepted "best" way to start building a world?** Or maybe a list of don'ts when getting started? Do you start chronologically with the formation of the world, or maybe start with a small town and characters and build the world around them, or maybe a single creature and what sort of world would be able to sustain it? I'm trying to think where to start but don't want to paint myself into a corner. I'm not sure how subjective/opinionated this stack tends to be, so please let me know what I can do to make this question answerable. [Answer] I used to work as a paid GM, and built many worlds, and have later been working on many other stories (both by myself and with others). And in my experience, the best way to proceed (again, by my experience, this is my method) starts with one big question... **Have you already started building a storyline?** If **the answer is "yes"**, the best way to proceed is a large series of "why's, and what's" digging further and further back. > > Okay, you have a princess... why? Okay, you have this kingdom... why? It was founded by a warlord... > why? He got people to follow him, why? The problems they were trying > to escape that got them to follow him... why? The land was in > turmoil... why? Massive famine... what caused this? Massive crop > failures every hundred years? Why? The goddess of spring leaves during > that year regularly? Why?.... > > > Then you follow up all the why's with "also results in..." > > "The Goddess leaves... which means the famine is during a year-long winter." > "The land was in turmoil in the snow... means the warriors fought well > in the snow who survived." "Those who followed were battle-hardened, > hungry, and weary, and fighting for survival." "These attitudes > founded the kingdom. There's a tradition of utilitarianism, doing > what's required to survive. Maybe your princess is drawn to the finer things in life, things of elegance, and is tired of the coldness in her land. Or maybe she's a warrior princess with battle scars. Or maybe she's weak, and an embarassement to her linage. Maybe she's an acolyte of the goddess and fears the next winter. How she fits into her society drastically shifts when you know the whys. > > > If **the answer is "no"**, then the best way to proceed is from the beginning. Like, THE beginning. As in, "before there were people, before your world existed, what was the foundation of the universe?" Was it a big bang or was it "created by gods" and if gods, where did those gods come from, how powerful are they, and what are the limits of their power, is the universe real or a simulation, is it the dream of a butterfly... etc. etc. Answer the deep philosophical question about your universe first. Now the world... is the world created or is it the result of the smashing together of massive hunks of rock? What kind of sun(s) does it orbit? How far is it from it/them that affects temperature? It's tilt that determines seasons? Stronger or weaker gravity (and side effects?) Is it filled with obviously planned mountain ranges and regularly placed ore deposits or would it make more sense to design the terrain in a random map generator? How long as it been since your initial map was the case? Have the continents shifted, have geological events or wars of gods moved things (if the latter, why, what was the strategic purpose?) Shuffle your continents, see where your resources end up. Where did the dominant species on the planet (probably humans for simplicity and familiarity) start from? How did they spread? How would animals evolve for each of the regions? What got domesticated first? Who were the oldest, why did groups leave/split/etc? When did wars happen, why did they fight? How fast did technology advance? Which types of technology were most important? What's ahead of our world tech-wise? What's behind? What are the present day borders? Also, addendum to that (you'll need to work on it where it fits in) Has humanity contacted anything other than humanity? Before figuring out how they meet, figure out where they come from and how they fit into the greater world. Okay, now that part done, when, with the two storylines, did they meet with their respective cultures? Work with both cultures seperately before they meet. How did the meeting go? How did resulting political events shape the political boundaries? Etc. etc. [Answer] I don't know if there is one "best" way to start building a world, but I do have one piece of advice which would help with a *remarkable* number of troubled worlds out there: Don't set anything in stone, unless you have to. Recognize that your first ideas probably have some issues with them. Find ways to see how the world would act if those ideas were true, without *requiring* them to be true. Then, when you realize there's issues, you'll have left room to adjust. Feel free to get it close to set in stone. Some decisions you make will have long lasting side effects that are hard to undo, but try not to do things you feel cannot be undone without ruining the world. Those are the things that get you in trouble. In other words, you don't have worry about painting yourself into a corner, as long as you make sure you can just move the paint out of your way before it dries. This is worldbuilding. Levitating paint off of surfaces so you can escape trecherous corners is pretty much standard issue world building material! [Answer] There's no best way, just as there is no best world and no best story. Generally, people want to build worlds in order to tell a story. What sort of story do you want to tell? I can think of at least three categories of story, which depend on the level of particularity you desire. The most general would be something like, "I want to explore a world which is 90% water, with wind-powered ships sailing between the islands." Right. Now you need to start from the top and work your way down. You really ought to think about weather patterns in the absence of large landmasses (storms with large fetches will likely get ferocious), just how big the islands are going to be (a few large ones or a whole bunch of little ones), and how shallow the oceans are. Umm, and anything else you can think of. From here you can start thinking about ecologies. Move on to creating your society. At the lowest level, "I see a young woman, cast on her own resources by the death of her parents, making her way in the world." This, of course, mandates an entirely new set of priorities. Her society is what counts, and from that you start creating the tech level (low tech levels imply low agricultural efficiency, and most people live on the farm - just an example) to support your society. Of course, even a low tech level can have decent-sized cities (Rome, for instance) and you can take advantage of that. From there you fill in the physical aspects of the world, but these are less critical to your story (most of the time - but watch it). In between, you might start with the society, and use individuals to illustrate it, "I see an egalitarian utopia, current tech levels, under threat by primitive invaders." Here the society (in the sense of the collective function, more than social interaction) takes center stage, and things like planet-building become less important. With that said, it's easy to get things wrong. On the functioning of medieval societies, Poul Anderson's [On Thud and Blunder](http://www.sfwa.org/2005/01/on-thud-and-blunder/) is instructive. There are other articles out there on various aspects of world-building. With that said, paying too much attention up front to the world is not necessarily a great idea. Most stories are about individuals, and to some degree you can always come up with details that support your story. Getting too picky about the setting rather than the characters is not a sign of a good story. Plus, of course, there's the matter of style. If you can get the reader invested in the characters early, and you keep the story interesting, you can get away with a lot. It's called "suspension of disbelief". You have to be careful not to drop some howler into the plot which breaks that disbelief, but that's a matter (as I say) of style. Finally, of course, there's magic. With magic you can do pretty much anything to your world and (again, it's a matter of style) get away with it. If you want to do this, I recommend reading older fantasy for inspiration. The current fashion in magic is peculiarly constrained and mechanistic, and often worries about things like energy flow and sources. Trust me, this is a terribly limited view of how people can conceive of magic. Prior to, let's say, the last 20 to 30 years magic was commonly written about in much more powerful terms. [Answer] I don't have that much experience in world building, but one thing I always try to keep in mind is: Why am I creating this world? What do I need it for? If you are just creating a world in your spare time, as a mental exercise, go right ahead and ignore this. If you, on the other hand need it for, say, an RPG or a book, make sure you understand what that product is going to need from your world. One example would be a short story. Since you are trying to tell a story and creating a new world for that purpose, there have to be something that sets it apart from the real world. In that case, I would try and figure out that 'otherness' and identify what you need to get there: Maybe the atmosphere is different or social structures developed in a different way? I hope this helps you. [Answer] # What if? The first advise I would give you is to **start with a *what if?* (or at least a question) and develop from there**. Because from this first *what if* are going to come all the other questions that will help you build your world. Take one of my personnal examples : > > What if humans didn't shape the world but another species did? > > > This *what if* was at the very base of one of my favourite worlds among those I imagined. It immediately implied other questions : > > What species could this be? > > > How would the world look? > > > Why is this species above humans in this world? > > > What are their behaviour towards them? > > > How do humans organize, what do their society/ies look like? > > > And so on. Every answer will build a new aspect of your world and **small answer by small answer it will start to make sense**. My second advise is to **avoid including things to your world for the sake of it**. I have done this so many times and that many times I made my new worlds inconsistent and senseless. While **it is great to always have our new world in a corner of your brain** so you can make connection between it and everyday situations, not because you think about something nice means you must include it in your world. You see a cool ninja film and that makes you want your characters to use shurikens ? Think twice. Why would they use shurikens; is that even relevant in your world ? **Everything you put in your world must result from a question so that it is justified and useful in making our world consistent**. Don't think about why your characters are using shurikens, but think about what weapons they would use and *then if* shurikens are the most logic ones, make them use shurikens. As said Cort Ammon before me, nothing must be carved in stone and never hesitate to change things if you realize they just don't fit. Once, I invented a world that took me a year to develop. After one year if found it was just not right so I rebuilt it, keeping only the core elements. I know theses are difficult decisions to make because you get to love what you created, really quickly actually. But **if you get to a point where you are trying to justify every inconsistent but cool aspects of your world with weird, forced explanations, you are going the wrong way**. Even if you love a character, for instance, don't hesitate to rework, nay remove him or her from the story completely if you find out he or she is useless to it or makes no sense in your world. --- Of course these are my personal advises and I am convinced everyone has their methods. Don't take my *what if* approach as the only way. I hope it helped you :) [Answer] # What do YOU want to do? Why? The first question is always: why am I doing this? What is my goal? What do I aim to achieve? Four categories of answers usually turn up: * I want to tell a story, and I need the world for the setting * I want other people to use the world to tell stories in, or to play in it * I want to explore one or a few "What If" scenarios * I like to build worlds for the sheer creative satisfaction of it The answer to this question sets a few rules for you when you create your world, and provides you with a goal that you should not forget. Where you go from there almost deserves their own respective follow-up questions and their own answers. But this question - and its answer - should always be your starting point when you build a world. ]
[Question] [ I'm looking for help hiding a small colony. Imagine a few families, definitely less than 100 people, living in a small community together hidden from the modern world. They use 19th Century technology and seek to remain hidden. Where in North America could this be possible? Assume that they work the land themselves and are self-sufficient. [Answer] Sounds like you are setting up something like what exists in [M. Night Shyamalan's The Village](https://www.imdb.com/title/tt0368447/?ref_=nm_knf_t3) which is set in Pennsyvania. I think something similar could be set up in any decent sized forest area. Buy a few hundred acres far from the closest town and hollow out a spot in the middle for your settlement. As long as no highways run too close to your land, you could probably even leave it unfenced. Just use the trees to block line of sight. I'd suggest something a little further south so that the winter's aren't horrible. Fighting northern winters with 19th century tech is not fun. [Answer] ## Hidden in plain sight: You can't really stop people (at least the government, with satellites) from seeing your community without magic. If nothing else, the folks looking for pot fields will see you growing things in the woods and think you're hiding something. So you need to decide exactly WHAT you're planning to hide. Are you trying to conceal the physical town? Without building the town itself underground, in a historical place, then you can't hide the town. So I'd suggest you need to hide the community. The Amish live a life just like what you're describing. They live a simple life in a low-tech way, without electricity, cars, etc. But even the Amish have a dependence on the outside for manufactured goods and markets. It's almost impossible to be totally isolated from your surroundings. So think about what it is that your community wants to hide, and specialize hiding that. So some of these details will depend on exactly what you want to conceal. To physically isolate from the outside world, pick a small island in the middle of the great lakes. I'd go with some place like [Beaver Island](https://en.wikipedia.org/wiki/Beaver_Island_(Lake_Michigan)), which did, actually have such an attempted society. Several attempts have been made to establish insular communities or even independent countries on islands in the great lakes based on ideologies, religions, and such. People will sort-of know you're there, but if you choose to be detached, few people other than in a couple nearby harbors will know about you. With a cover story like, "We're an offshoot of the Mormons/Amish," people will know there are folks there, but that there isn't really anything to see. There are other island areas off of coasts that would provide a similar level of isolation. Now you need to keep you own people from wanting to leave or know about the outside. Nothing will spread the word about your community like a few ex-members talking about sexual abuse and cult worshipping. What mechanism do you have to keep the members in place? Are they werewolves? Do they all speak a unique language? The physical isolation in the middle of a great lake helps, but someone determined enough WILL leave, and even in *The Village*, there came a time that someone needed to step outside the fold. [Answer] **Indian reservation / Indian reserve** [![aboriginal land claims](https://i.stack.imgur.com/06ZkJ.jpg)](https://i.stack.imgur.com/06ZkJ.jpg) <https://native-land.ca/land-area-comparison-canada-and-land-claims/> If you do not want to be found, you can be invisible. Or you can be in an area where people do not look and if they do they assume you are other than what you are. There are very large, very lightly populated tracts of land in North America where native tribes have sovereignty. The Navajo reservation in the US is immense. The linked source estimates 35% of Canada are Aboriginal lands (from the viewpoint of the Canadian government; from Aboriginal viewpoints, most of the country is unceded land). Persons living in these area might not have to pay tax to state / local government. They might or might not have to pay tax to the native authorities overseeing the land. I can imagine a scenario where your people live in a remote area in Canada on an Indian reserve. The tribal authority sort of knows some people are up there. They are not sure if they are natives or not. Those people cause no trouble and ask for nothing. The native authority has its hands full with events on their other lands, and so leave well enough alone. Maybe someone checks every couple of years. The state and national authorities know even less. They might be aware there is a settlement because they see it by plane. They know it is on native lands and assume they are indians, and leave it at that. [Answer] **[Frame Challenge](https://worldbuilding.meta.stackexchange.com/q/7097/40609)** In a comment to another answer you mentioned that your proposal was something like M. Night Shyamalan's "The Village." It would have to be, even to an extent greater than Shyamalan's movie. It isn't just Google maps/Earth that's the problem. It's hikers and hunters and fishers and mushroom pickers and campers and real estate agents and their clients, and resource developers such as loggers and oil and minerals and... well... the list is very long. While there are a great many square feet that have never felt the touch of a human foot, there are precious few (if any) square miles that haven't enjoyed the close scrutiny of humanity. And considering the history western civilization has had with small, isolated communities with a strong resentment for outside interference (frequently described as "cults"), it's hard to believe that the moment they were discovered (an inevitability, IMO, the point of this challenge) wasn't also the first day they would be analyzed with a microscope. And to make things worse, we have drones. Big military drones. Small personal drones. Drones of all makes and models that can travel vast distances at great heights with pretty good cameras. Your 19th century community would need to engage very, very 21st century legal and political acumen to retain their privacy and isolation. And the moment you allow that, it's really just a group of people pretending to live 19th century standards. And once you allow that, they can be located almost anywhere in North America. Greater than 60% of the U.S. and probably more than 90% of Canada are rural to wilderness. [Answer] **Live Underground** There are many instances of large communities living beneath the surface. The largest one I know of was [the City of Derinkuyu](https://en.wikipedia.org/wiki/Derinkuyu_underground_city) in Turkey. Locate the community in a rural area well away from highways or other communities. I would choose a dense, forested region as it will deter most humans. It will also work to obscure smoke from cooking/heating fires and make aerial detection by satellites and drones harder. The community's largest difficulty will be growing food. As they would not want to farm above ground, they would need to have sunlight chimneys with mirrors and/or lenses to bring light to the subterranean fields. But still doable with 19th century technology. Another potential difficulty is the fact that North America has a lot of comparatively hard rock. AFAIK, creating and expanding the community will take time and significant labor in most places with dense forests and may be hard to hide. [Answer] ### Living on an island... As other answers have said, anywhere on the mainland risks discovery by random hikers, hunters, firefighters, BATF investigators, etc.. Of course you can kill them, but most of them will have told people where they were going, so their disapearance will guarantee some pretty good investigation within a 20 mile area of their last known location and either side of their expected track. In particular, there will be extensive use of helicopters and drones. More likely would be an offshore community setting up shop on an island which is not too near major routes. Peter Benchley's novel [The Island](https://en.wikipedia.org/wiki/The_Island_(Benchley_novel)) supposes exactly this situation (with pirates). Benchley's community is not fully self-sufficient, requiring regular looting of passing boats, but is reasonably close to it. Piracy of course requires complete secrecy, so anyone encountering them either has to die or join them. A closed society though merely has to be unwelcoming and turn away visitors. If they only get the occasional lost yachtsman noticing them, word is unlikely to get out for some time. Naturally an aircraft overflying at a reasonably low altitude would see the crops, but it may not be anything they'd particularly comment on afterwards, and most aircraft won't be low enough to see much. It's hard to keep track of exactly which small islands are or aren't inhabited, after all, and some are only inhabited sporadically anyway. Of course Google Earth will pick up this at some level of detail. Google tends only to use higher-resolution imagery on land though, so you won't be able to see too much; and for anyone to notice this community would require someone to intentionally find this island and zoom in. Eventually this might happen, but it's not that likely. This could even be a plot point for why your protagonist is the first person to find them. [Answer] # They need outside protection As others have noted, a farming village can't hope to remain undetected just keeping to themselves. So what they need is someone from wider society protecting them. On the outside you have two options: Either you have a two-part cult (something like "The Innocents live a sheltered live, the Guardians serve them by shielding them."). Then the outside facing cult would be known, would own the land, would provide cover stories, would mostly adapt to modern life and would keep anyone away from the inside cult. In this variant, you may get away without the colony actually knowing. The other option would be a really long lived notary office. The founder of your colony was really rich, set up an endowment and a contract with the notary office. They act on behalf of the actual owners of the land (the colony as a whole), handle all business with the outside world and keep everyone away. I think in this variant you definitely need someone on the inside knowing. While such a long-running contract seems plausible, the office would want to get in contact at least every decade or so. (This idea is adapted from "One Trillion Dollars", a novel by Andreas Eschbach.) So on the inside it could be that the cult leader/mayor/priest/xatriarch is the only person with connections to the outside. (I mean, you anyway need a reason why no single person in 125 years ever left the village, so you might as well work in this exception.) There are regular 1:1 meetings and the "ambassador" role is handed down from generation to generation. The ambassador keeps a secret what they actually do when they go into the woods alone every new moon (or whatever). [Answer] **Central/Eastern Alaskan wilderness.** Your community will need to identify a large tract of private, undeveloped, forested land with access to water that they know the land-owner never visits. Given that, in certain parts of Alaska, the community will be quite remote and will generally be left alone. Hunting, fishing and basic agriculture done without clearing trees could sustain them without showing a large satellite footprint. Winters will be brutal. Keeping them *completely unknown* to the county government would be a challenge, but with careful construction of disguised dwellings, or perhaps living in a cave, in the midst of a vast territory, it is not unthinkable. Individuals would probably be seen from time to time, but could explain themselves as hikers or tourists. [Answer] **Frame challenge: Such a colony might die out quickly** Such a small community will have a hard time sparing the calories to feed just a smith. If the smith dies, or his (single) apprentice is inept, the colony won't make it even into the second generation. They'll also have no buffer to survive any disaster. A single bad harvest would force them to give up or die. And a bad harvest can have many causes: Weather, flooding, a horde of wild boars devastating your fields, plant diseases and plant parasites. They could live as hunters, but then there would be good years and bad years. The one risk that couldn't be eliminated at all would be human diseases; these can easily kill 10-90% of the population, and below a certain threshold, the colony just isn't viable anymore. (Plus many diseases leave their victims enfeebled, so they can't gather the resources to survive the next winter.) Long-term, inbreeding will most likely make the colony fail. It's not very likely to happen in the 1900-today timeframe, but it could be a plot device if some colonist somehow finds out (or knows from pre-colony education) that the general consensus is that a human colony needs roughly 1000 members or more to avoid inbreeding. 100 is far too few for any long-term plans, so the founders would have to be either ignorant, or planned to go out of isolation within a few decades, or have started with 1000 persons but some disaster struckt. [Answer] A strongly appealing scenario for perhaps many people. Hope there are many such communities already out there. Agree that a fully non contact community has a struggle with resources, gene pool, and for most, hard to be long lasting. Have mildly considered similar idea in Australia, set up perhaps in 1840's, and inventing own steam 'gothic' technology. Explored local mountain area and found a few very good sites, one of them showing faint traces of previous long term 'camping'. In a mountain area could always show up as cloud covered spot on mountain in Google Earth, using a cloud generating device. Much of it could be underground. Contact with modern world may not be a problem, just the benefit of a counter cultural refuge. Possible to have PV cells just looking like natural rock etc. Vent for fire in cave, could look like a campers fire just left smoking. Of course if somebody or govt gets suspicious may be difficult to avoid detection, but for most of time nobody is looking. ]
[Question] [ Building my sci-fi setting deciding what's the in-universe answer to the [Fermi-paradoxon](https://en.m.wikipedia.org/wiki/Fermi_paradox), the reason why the universe still seems to be empty of K3 civilisations despite its age, has been quite important to me. I've settled on the notion that a species with a "functional setup" on a "suitable world" arises once per billion years per billion stars, but that a series of strong filters keeps everyone else from building galactic empires. Mankind is the only great civilisation in the next dozen superclusters. The enormous distances of space and time make seeing other civilisations in this early age of the universe impossible. I have most of these filters pinned down, but the last filter should be that FTL is a suicide pact technology. This means that while FTL is theoretical possible in my universe, as soon as you use it to violate causality you are toast. I've encountered this idea elsewhere before, but the suicide part was either way too strong (the entire timeline where causality was violated stops existing) or way too weak (only the researchers and equipment working on the FTL project and all the data implying that there ever was such a project and such people stops existing). **I want a "causality correction" that wipes out a possibly already interstellar civilisation for good, but leaves ruins, artifacts and enigmatic data for my protagonists to find.** I'd love it if the apocalypse would be spooky and enigmatic. However it should not wipe out a civilisation which has already spread to several thousand star systems, although it is acceptable if the event destroys hundreds of systems of such a civilisation. **What exactly happens?** The setting is supposed to be sci-fi as hard as the narrative can take, but this is my little bit of Lovecraftian horror in the setting. Causality violation shall be a spectre that is enigmatic, unproveable and devastating. The best answer will survive a meeting with [Occam's razor](https://en.m.wikipedia.org/wiki/Occam%27s_razor), yet still give me the desired horror aspects. [Answer] **The final great filter** Any civilisation that attempts FTL causality breaking will very quickly twig that it can be used for all sorts of *shenanigans*. This means the any race brave (or foolish) enough to make the attempt is destined to become a race that uses these causality bending effects for their own gain. To whit: they’ll be time travellers. But no race is perfect, especially not when your descendants can come back in time and shout at you for doing it wrong, and so divisions will quickly appear. Factions will rise, extremists will pop into existence, and thanks to the fact that you have a race of time travellers you will suddenly find that *every era* of your race’s history is filled with war. Endless, unceasing, trans-temporal war. A race to the past will begin with each side trying to effect changes as far back in the history of their territory as they can, diverting almost all of their resources into temporal expansion instead of physical. Then there will be no safety from the paradoxes. Waves of history will make and unmake whole armies. Resources will be made, lost and never have been all the way through your race’s history, spawning countless enigmatic artefacts, disparate histories and blasted battlegrounds. Any race in contact with these time travellers will either join in the war or, recognising the danger, cut off all contact and seal away the madness. Of course, all things (even those across time) must come to an end, and your time war will eventually fizzle out as the complexities of keeping track of the endless variations of causal violations prevent any meaningful ideological conflict. The survivors might ban time travellers and try to rebuild, but it’s simply no longer possible. Your race will eventually be utterly destroyed by alternate versions of itself, as terrible trans-temporal weapons unleashed centuries later land on communities barely getting by after agreeing a ceasefire. Occasional war machines or bands of half mad soldiers pop into existence, flung across spacetime by the vagaries of relativity, and slaughtering everything around them before getting sucked back into whatever tangle of probable futures and pasts spawned them. Any races that joined them will either be similarly annihilated or might have any contact with them erased from history. Even these last spasms of spacetime will eventually cease, leaving nothing behind but ruins that (as far as any other race can tell) have always been there. Now, a race sensible enough to not try exploit this (even if they do it once and then back the heck away) won’t ever trigger this apocalypse, and will pass the last great filter, and any race lucky enough to engage in it and *survive* can only do so by editing a deep fear of causal violations into its own history, thus leaving that race (narratively speaking) no different to any other. It also has the advantage that you don’t have to really *explain* the nature of trans-temporal war for this explanation to work, as for the purposes of your story no race can engage in it without risking annihilating itself from history and leaving nothing but ruins behind. [Answer] **You exist in reality, where causality will not be violated** A reality with FTL, can not exist and it have never existed. Actually what happens is controversial pending on interpretation of quantum physics: * if multiverse actually exist, then all timelines with FTL simply end or even are retrospectively removed (for practical purposes think this way, regardless whether from technical perspective it's the right one, there is a survivorship bias - you are in timeline in which FTL has not been activated) * if there is not multiverse, then reality sort of follows a path when mild random quantum fluctuations are diverging towards a path in which causality would not be violated But the second explanation does not sound scary enough, right? Right??? Not necessary, if you're near discovering FTL, then otherwise unlikely events would happen against it, so actually it would not run. Effectively reality would follow the most likely path in which FTL would not be launched. So a minor explosion? Depends. Does it stop whole research or merely delays it? Delays, so every week there should be another highly unlikely accident? What's a cumulative chance of such events? Insane low. Collapse of whole civilisation is more likely than that... So the problem is not obvious. You don't see many exploding FTL drives prototypes. You just see dozens of civilisations that were on straight path to create in decade or century a FTL research project... and somehow diverged to a path when this did not happen. There is no fixed pattern of destruction - war, economic crisis, computer virus, weird culture shift against technology, virtual reality decadence, other unrelated experiment going wrong. You only observe the scenarios, in which FTL was not to be constructed. The only clear and odd pattern for an observer, is the more advanced and technological minded civilisation, the more likely something odd would go terribly wrong. *Bonus: the pattern that would happen should be also noticed by other characters, but could be interpreted as usual decadence and moral decay. For bonus horror points a one should notice that his civilisation is on verge of a total war, so is trying to develop a FTL to bail out himself and family.* *Bonus2: as you are going to be need all unlikely scenarios how civilisation missed their chance for ultra high tech, I can drop a few less used ideas (another grey goo, nuclear war and global warming... [yawn]):* * *Read Ted Kaczynski "Industrial Society and Its Future", there are quite a few original thoughts, why people would feel badly in seemingly nice high tech society.* * *We're right now running a serious dysgenic project as high IQ individuals are having less kids plus thanks to safety net and modern medicine usually deleterious mutations are not being eliminated. Potentially such mechanism could make a civilisation stuck in situation, where it's no longer producing enough geniuses to actually advance civilisation (to be able to produce designer babies), while simultaneously it would be good enough to maintain otherwise quite high tech civilisation* [Answer] Here's a possibility that doesn't quite meet your criteria, but is somewhat closer to actual, known physics: Invoke the [Chronology Protection Conjecture](https://en.wikipedia.org/wiki/Chronology_protection_conjecture). In short, this conjecture asserts that whenever general relativity would appear to make time travel possible, quantum mechanics will step in one way or another to thwart it. It's an explanation for why we haven't seen any time travelers yet. Say you invent a device capable of creating stable wormholes. Cool. It works fine, until you get the two mouths of one wormhole close enough to each other that you can use it to travel backward through time. Suddenly, some virtual particle mumbo-jumbo happens, and both mouths collapse into inescapable black holes. If you build an Alcubierre drive, as soon as you turn it on, the warp bubble will irradiate its interior with Hawking radiation so intense as to incinerate both your starship and the drive itself. And heaven forbid you try to use a jump drive to save on propellent in getting spacecraft into orbit: The black hole that collapses into will be big enough to consume the entire planet over the next century or two. Maybe it is possible to build an FTL drive that actually works and doesn't destroy itself, but any given civilization is far, far more likely to destroy itself by accidentally feeding their home planet to a black hole than to get it right on the first try. And those that do manage to survive their first FTL failure are unlikely to try it again. [Answer] ## Time Traveling Super-Viruses I think a mundane answer might be interesting to consider: any interstellar civilization developed to a certain point will have to have an extremely high level of medical know-how. With this know-how, they will have eliminated some of the pathological organisms (eg. viruses, bacteria, etc.) that are less adaptable, with only the most adaptable and deadly viruses surviving until that age. Using the FTL technology, the civilization will probably attempt some experiments with time travel, but any time traveler, no matter how well disinfected, risks carrying pathological organisms back in time. When these highly advanced organisms are taken back, they will adapt and advance even more quickly than before, given a lack of medical know-how in treating them. The further back the traveler goes, the more time the organisms have to evolve even further, and the less prepared the civilization will be to welcome it. This is, of course, presuming we operate on the principles of creating alternate timelines when we introduce causality errors and paradoxes when violating causality. With each loop back, it will be like a positive feedback loop for the pathological organisms, as each loop back will make the organisms progressively stronger (we bring the N-strength organism back, causing it to be N+1 in the future, when we go back again, it becomes N+2, etc.). If too many time travels are done, the loop will have made the pathological organisms deadly enough that the living creatures on the entire planet will be wiped out, leaving only the artifacts behind. This should fit the bill of a gloomy/creepy planet, and a dangerous one too; there would be a conspicuous lack of almost any living creatures left on the planet, with a select few more adaptable ones harbouring incredibly deadly viruses. Any dormant super-viruses left on the surfaces of the artifacts could also pose an extreme risk, threatening to wipe out entire civilizations should they be accidentally brought back with the artifacts. [Answer] My approach to punishing violations of causality is a phenomenon that I have dubbed 'Paradox Reverberations'. Let us suppose that we have a time traveller who goes back in time. Should this time traveller do something that invalidates the course of events that led to the time traveling event, a reverberation begins... time flows onwards, the time traveling event does not take place, and since no time travel event occurred, reality resets at the instant the paradox occurred, restoring the preconditions for the time traveling event... or does it? The thing is, quantum fluctuations will ensure that the unfolding of the sequence of events between the paradox-causing event and the time traveling event will not play out deterministically... but the differences may not be sufficient to prevent the time traveling event during any particular iteration. This leads to alternating temporal paradox / normal chronology sequences, though each iteration will play out differently due to quantum uncertainty, until a chance sequence of events occurs that breaks the loop, preventing the paradox from occurring. From the point of view of the time traveller, they can only be aware of the latest iteration of the paradox reverberation loop, so to them it would appear that some event occurs in the non-paradox part of the loop that prevents them from going back in time, or having gone back in time, prevents them from causing the paradox. A paradox reverberation, once broken, would appear to have the appearance of an incredibly unlikely sequence of events that just happens to lead to its causative event not occuring in the non-paradox part of the loop. This may be highly localised and specific, resulting in no more than the time traveller simply deciding not to perform the actions that cause the paradox, or it may be entirely more catastrophic, rendering the time-travelling event impossible. Since the paradox reverberation will continue to cycle until a chance sequence of events invalidates its preconditions, potentially billions of times if necessary, it would have the effect of being an infinite improbability engine: whatever sequence of events that is necessary to prevent the paradox *will* occur, no matter how improbable it seems. Should use of technology with the potential to cause paradoxes come into common use before a paradox reverberation is initiated, it becomes quite likely that, should the first reverberation catastrophe not invalidate time travel, the first reverberation catastrophe could trigger further time traveling in an attempt to prevent the initial catastrophe, each additional event either invalidating the initial paradox reverberation's exit conditions, reinstating that reverberation, or it may cause an entirely new paradox reverberation. In such a case, the only exit point becomes a highly improbable sequence of events that prevents *all* paradoxes. Something sufficient to prevent any further time-travel paradoxes in a setting with many time travel machines, especially if they pre-exist the earliest time-point of the oldest reverberation loop, is likely to be both highly improbable and calamitous. What would be left after the exit event of a paradox reverberation involving multiple time-travelling devices? That may be highly variable... but it is highly likely to have the appearance of a sequence of highly *un*likely and calamitous events. [Answer] Every time a FTL spaceship violates causality and returns the systems it departed this sets up a temporal barrier. Every subsequent FTL vessel that violates causality, these will come newly spawned timelines created by the first and any subsequent causality violations. Effectively every FTL spaceship will return to the same point in time. They are effectively cut off from returring to the futures from whence they came. Each spaceship will be equipped with technology and weapons vastly superior to those of the system from which they originally departed. Naturally they will want to conquer this system or planet. The problem is all the FTL spaceships will have to fight all the other FTL spaceships. The most probable outcome will be total annihilation for the civilization that dispatched the FTL spaceships in the first places (that's because multiple converging timelines will be involved). Only rubble will remain. Should one or two FTL spaceships survive the destruction of their native civilizations, they will be doomed to ply the spaceways like some galactic version of the *Flying Dutchman*. Preying on lesser civilizations like the Lovecraftian eldritch abominations of old. [Answer] You could perhaps have FTL trigger [vacuum decay](https://en.wikipedia.org/wiki/False_vacuum#Vacuum_decay). The FTL drive could somehow trigger a vacuum decay, which would more or less ensure everything around the source would be destroyed at the speed of light. Nothing of the civilization in question would remain which fits great with the apocalypse part of your question. The problem with this apocalypse scenario however is that (at least to my understanding) it wouldn't just stop there. It would keep expanding until everything is destroyed. One possible workaround would be that if the expansion rate of the universe is faster than the speed of light, the false vacuum bubble wouldn't reach other galaxies. This only leaves the fact that you want some sort of ruin or artifact for the protagonist to find. The only thing that really pops into mind is that if the person testing FTL traveled far enough and reached another galaxy, he could (in theory) be the only survivor (albeit briefly) of that civilization. If/When they die in the middle of nowhere it could be a potential artifact for the protagonist to find. I'll admit I don't really know enough about the subject to tell you how exactly an ftl drive could cause vacuum decay, but it seemed apocalyptic enough to post as an answer to this. [Answer] **Gradual degradation of spacetime collapsing into oblivion** FTL travel has exactly the expected causality breaking affects, except it just happens incredibly slowly at first and builds exponentially as the technology is continuously used. Say it initially begins at the site of the first FTL launch, but nobody actually notices aside from a random, nearly undetectable spike of energy, or interference, or what have you. This continues to happen with each new FTL launch only the affect is doubling in strength each time, while simultaneously doing the same at the previous launch sites. This becomes noticed, but not quite as fast the technology takes hold as a staple of the civilization. Ultimately the gradual collapse becomes powerful enough to actually disintegrate matter and seems to stem from the civilizations central planets where the FTL experiments originally began. Unaware of the cause, individuals attempt to escape the expanding wave of destruction by the fastest means they know, FTL, and end up compounding the problem so that everything the civilization has built simply cascades into dust. You could almost think of it as a massive pain of glass, that you throw a small rock at that only scratches it. Then you throw another rock that also only scratches it, but it causes the first scratch to grow deeper. Then a third rock deepens the second scratch and the first becomes a crack. This affect continues with each rock, expanding more and more cracks into a larger and larger web of fractured pieces. Eventually the glass can't resists anymore and simply shatters. As for having ruins, you could come up with some explanation, like remains of what existed before FTL travel existed, or explain how some materials were shielded in some way, or simply had the structure and/or luck to resist the destruction like the Nagasaki Arch surviving the atomic bomb. [Answer] **FTL has a slow, cumulative effect on the very fabric of hyperspace** We assume that FTL requires to jump into a different section of space-time (let's call it hyperspace) and back to travel FTL. When the first civilization were born (probably around 10-12 bilions of years ago), the hyperspace was very easy to access. Developing and using an FTL drive was relatively cheap and easy, but what nobody could foresee was that every FTL jump slightly damaged the structure of hyperspace (both on a universal scale and - on a bigger amount - on a local scale). After a cumulative of some tens of thousands of jumps, these damages cumulated up to a threshold level, after which the hyperspace sudden became harder to access, requiring much higher energies than before. This basically brought these civilizations into a cul-de-sac, since at some point the engines of their starships suddenly could no more access the hyperspace and travel FTL. As a consequence, all of their supply routes became unexpectedly impraticable, leaving isolated, non-self-sustaining colonies and decadent single-planet civilizations. They could no way discover new technologies to access hyperspace again, so they slowly decayed into barbarism on their home planet and got extinct on the other colonized planets, leaving only ruins. And through the eons, every following civilization had to invest increasingly more energies and resources in developing and operating FTL technologies, every time without realizing the long term effects of their use of hyperspace. [Answer] **Ripped.** Spacetime in the area where FTL was used gets ripped and stays ripped. Causality becomes unpredictable. The laws of physics can change, and are mutable. Other adjacent timelines are affected by this deep tear and things can bleed through - or come through the gaps. Strange eddies produced by this disturbance can create new things or allow the emergence of things that once were. Property values plummet. Solemn angels arrive to darn up the edges of the the tear with [reality anchors](http://www.scp-wiki.net/forum/t-1438186/what-is-a-scranton-reality-anchor-sra) and prevent its propagation. These anchors stabilize things enough that the vicinity of an anchor can be used as a base from which to explore The Torn. ]
[Question] [ So one of the biggest quirks of the world I'm building is that, along with supernatural powers suddenly becoming real in modern day, the human race is granted multiple separate opportunities to voluntarily transform themselves into exotic and never-before-seen humanoid species. Periodically, for the first few years, everyone on earth is given the body of a new species to try out (the same species for everyone on earth each time) and they're given a week to decide if they want to stay human or become this new creature forever. Essentially, previously all-human modern societies are now also populated with fantasy races through an opt-in system. Now, since this *is* an opt-in system, obviously people have to *want* to make the jump, which means it has to be tempting to at least a sizeable chunk of people. Now obviously this for the most part excludes making any of these creatures things that humans wouldn't find sexually attractive (so more like elves, less like orks and trolls), but I'm pretty sure it takes a lot to make somebody throw away their entire physical form in exchange for a new one even if it *isn't* creepy or gross. So I brainstormed a while for a system that could make it tempting without making these species objectively better than humans, and the system I came up with was that your new body was totally genetically randomized. The body could be male, female, tall, short, anything. The human body you started with has no bearing whatsoever on what your new body will look like. This I think would tempt a lot of people. A lot of people, for whatever reason, lost the genetic lottery, and if there were suddenly a second one, one which some of these people proceeded to win the hell out of, I'm pretty confident a lot of them are going to be tempted. So with this system I'm picturing the following being the biggest reasons people took the offer: **1: The new body they were offered, through sheer luck of the draw, scores significantly higher on the attractiveness scale** **2: It was a chance to escape a sick, disabled, or genetically defective body and live a relatively normal life** **3: They're transgender and the body they were offered was the sex they identified as** **4: They just flat-out like the new species better and want to be one** Buuuuuut... I have this nagging feeling I might be missing something here, some other major reason somebody might want to make the jump, or possibly that I'm underestimating how many would belong to category 4. **Can anyone here think of any significant or noteworthy reasons besides these four that I'm missing here, and which I might want to bring up or show in-story?** [Answer] A few things I can think of: * Peer pressure: If all your friends and family decide to make the jump, would you want to be left out? * New rules: Different species with different physical/mental capabilities means this could open up new jobs and regulations which need to be adopted and during this shift having a new body will mean you can be apart of, or leader of, this change. * Incentives: If these fantasy bodies are potentially better for sick or disabled people, government could give incentives for people to make the shift. These incentives might provoke others to follow. * Different groups: People love to categories things [citation needed] and the pull of being part of a unique group will mean people are more willing to change. * Blackmail: What if people could be blackmailed/forced to change? You mention the fantasy forms would ideally be attractive still, imagine the unfortunate people involved in sex trafficking forced to change in order to appeal to wider range of customers. Scary thought. Rule 34 of the internet... * New culture: Just look at Japanese culture of manga and anime and I'm sure people will jump at the opportunity to carve out a new life as some of these fantasies creatures. What might be interesting is if you can switch back and forth between your human form and fantasy form, for example once a year or so. This might mean more people are willing to adopt it as you still have the option of return to "normal". [Answer] My list... * **Poor man's immortality.** I'm old, and the body I've been offered is young. It's a chance to live a second lifetime. * **Anonymity** + *I owe the Mob a LOT of money* and the body I've been offered looks nothing like me. Punishment avoidance in general might actually be one of the biggest reasons anyone changes races. And the bigger the crime, the more likely they'll opt in to avoid prison time. Worse still, and generally speaking, this may become a popular form of bankruptcy without all the hassle of contacting a lawyer and standing before a judge. An easy way to avoid paying debt. + *I'm running away...* from my family, from my job, from my abusive father/boyfriend/husband.... In this regard it could even become a form of suicide (identity suicide vs. physical suicide). I could even imagine the suicide numbers dropping as the opt-ins inrease, prompting a wave of government-funded studies.... * **I'm saved.** I have a terminal disease and my new body doesn't. Very obvious choice. Would also apply to the disabled in any form including blindness and deafness. It is, in fact, a way to correct nearly any genetic or accidental deformity or condition. Prompting more government-funded studies... * **Time to give Johnny the beat-down of his life.** Particularly popular with the Orc conversions will be the victims of bullying, because it's all too human to want to seek vengence. * **Glarnak's will be done!** Particularly popular with the cultists and those waiting for the aliens riding in the wake of the next asteroid. These religiously-minded people tend to opt-in in groups. And since [Glarnak is the god of worldbuilding](https://worldbuilding.meta.stackexchange.com/questions/2188/the-many-memes-of-worldbuilding/3789#3789), it's obvious that He would like as many opt-ins as possible. [Answer] In many fantasy novels or games, the non-humans depart from the human baseline. For game balance, they might not be better across the board, but they are better in many *stats* and they have *advantages*. * Elves are graceful. Elves are beautiful. Elves are near immortal. They may be a bit less sturdy than humans, but on balance, who doesn't want to be an elf? * Orcs are strong. Orcs have stamina. Orcs heal quickly. Okay, so they are a bit dumb and ugly, but there *are* compensations. And then there is how the change happens. *Would it be possible to identify the individual after transformation?* What about fingerprints? DNA? Could a divorced parent wiggle out of child support payments? Would a criminal record vanish? [Answer] Adding to other lists already given: 1. **Your culture says women are weak and feeble**, and have to stay at home and be protected by the manly, macho menfolk. Well screw you, patriarchy, now I'm a troll lady or giantess and can rip you weak and feeble human men into small pieces. So NOW try and stop me learning to drive or getting that job as a policewoman or soldier! 2. **I can't have kids.** Maybe this new body will be able to father children/bear children? 3. **I don't want kids.** If I become an elf and my other half stays human maybe we won't be cross-fertile... and our parents will stop carping on about grandchildren every time they visit. 4. **I'm pretty good at my job as a human, but if I was an [insert species here] I'd be awesome at it.** Elf for a supermodel, orc for a Rugby prop forward, and so on. 5. **My religious leader says that [insert species here] are God's chosen people.** It is my destiny and religious duty to become one. [Answer] ## People tend to dream they are someone else Look at roleplaying events: many people like to present himself as a hero or fantasy creature. Most of them could transform unconsciously. ## People tend to be different People change color of their hairs, made tattoos and even surgeon operations to be different. They think they will be unique but they are not. With some time a new species like *Terminator-man-with-gun-in-arm* or *Sweet-girl-with-big-eyes-and-colored-hair* would arise. --- In fact, I read some fiction stories where opposite problem has been arisen: **why many people still don't change their look**? It's too easy to want to be a little different and too hard to revert to original state. [Answer] "I'm an elf trapped inside a human body" Just as you have trans-gender people now, you could have trans-racial people... [Answer] A new body is like having a new life, even if nothing else about your life changes you're suddenly having to relearn how to type with new fingers, how to walk on new legs, how to talk with a new mouth and tongue, not to mention all the sexual stuff. I think the more extreme the transformation the more enthusiastic people will be to try it, have you ever wondered what it would be like to have and extra pair of arms, scales or fur or an exoskeleton, or a merfolk tail, what if you could have face tentacles like an illithid? A lot of people are simultaneously crushed by how mundane their everyday lives are but also too comfortable to leave the secure/predictable life they've set up for themselves, a new body lets them have the best of both worlds, their life doesn't change at all but everything in it feels different. Why be an elf or an orc when you could be an aarakocra, tiefling or aboleth? [Answer] I have some questions about this system. When you go into a new body how much are you yourself? After every transfer, you could have the same memories but will you feel different about them? The same action in one body may feel wrong in another body. A piece of music you love as human can evoke displeasure as an elf. Is the experience between different races the same? Can the races interbreed? Will one spouse hope to be an elf so they can have half-elf children with their other human spouse? What are the rules for establishing identify after the change? Must there be witnesses to the change to verify identify? Will the government accept that? Will your family and friends? When you become a member of the new race, will the members of new race accept you? Although getting traits are random, what is possibility that after the change the person in question looks like someone else? You wrote the system generates some attributes randomly. Who controls that system? Can that system be hacked to commit fraud or force certain attributes? Can you change back up if you try it and do not like it? [Answer] **Economics** Assuming changing is largely free, some bodies will offer more economic opportunity, a large portion of your poorest people will be forced into changing just due to economic circumstances. This may very well be your largest factor. Dwarves and mechanical aptitude, flying races, attractive elves, water breathing, temprature tolerances, night vision in general, each offers new economic opportunities to your person. It is the same reason the poor were often the most likely to go to colonies or move in unsettled areas historically. If they get to pick their race this is several orders of magnitude more powerful, since people will try to match skills or desires with the new race. [Answer] answering as prompted in your other question... **To be honest, assuming your starting world is anything like our world, getting anywhere near 50% take-up sounds beyond fiction.** Going through your suggested reasons: * Attractiveness – most of us – even if we aren't particularly attractive – are happy, and it's likely to look like some furry fetish if we transform into flawless animal-people. Also, cosmetic surgery already exists, but most people don't take it up not due to price, but because they don't want it. * Healthy body – some might take it for this reason, but a quick google suggests only a very small proportion of the (non elderly) population has a life-limiting physical disorder. * Forget trans; even optimistic estimates suggest only 1% has "some degree" of non-binary conformity. It's not going to give you a significant proportion. Additionally, I'd imagine someone who identifies as a female human isn't going to want to be a female cat any more than a male human * Prefer the species – I think many of us might wonder what it's like, but not want to do it long-term. The grass is always greener on the other side. I imagine a lot of people might take the 1 week trial each time, then revert. **Initial Offerings** For the first offering, anyone *even vaguely sensible* would avoid an offer of a species change. **There's too many risks & unknowns**. Will it work? Are there side-effects? Are they really killing people and replacing them with beastman puppets? What happens to my memories & personality? There's enough people who avoid the first release of an OS because it'll be problematic, how much more an unproven supernatural species change! A 1 week trial is also worth nothing on the first offering, as there's no proof yet that you can change me back! So once you've had *at least* a couple of offerings, and people are starting to believe it's for real, and doesn't have any major immediate side-effects... It's likely that the first people who take it up will be people with a **furry fetish**, or sex-workers who want to / are forced to monetise that. So that immediately means that – unless furry fetish has suddenly become respectable & desired (it won't in that time – look how long it's taken LGBT to become acceptable) – most people are going to look at it in a somewhat dim view. I think this is worth considering, because those who first embrace it are likely to set the tone for the overall thing. **Breaking it down** Let's deal with some easy demographic blocks... I'm going to skip 'Christian' (31%) because it's a very varied block. Wikipedia gives ~24% of the world's population as **Islamic**, and most of that will be in countries with some degree of Islamic law. Taking Indonesia as an example (it's one of the most liberal Islamic majority nations, and one I'm somewhat familiar with), the culture is still largely conservative, and species shifting is very likely to be seen as Haram. This is doubly so if species shifting is seen as a 'western' thing – which is likely will as the countries most likely to give it good press are western – or a fetish. So religious observance and social pressure will prevent them from taking up the offer – and in many Islamic nations, there would be punishments (either official or done by local communities) for anyone who did accept the offer. **China** (18%) will be your next largest block. It seems unlikely that the Party would look favourably on species shifting. It would likely be seen to go against the One China value. The current party is more traditionally communist, and has been stamping out anything seen as foreign / disruptive (e.g. clampdown on Christianity in China), so I think we can safely assume they would similarly take a very low view of species-shifting. It would also possibly be seen as disrespectful to one's family / community. It would be a career-limiting move. Your next biggest demographic block is **Hindus** (15%). My knowledge here is rather limited, so perhaps a commenter who knows more might help. For lack of anywhere better to start, comparing attitudes to LGBT issues, Hinduism is more accepting than Islam, but it's still not as accepted as in the west. Hinduism does of course have a big connection to anthropomorphic animals in its gods – I suspect that would make it *reject* shape-shifting, as e.g. it would be seen as disrespectful to Ganesha to accept an elephant trunk. On the other hand, it *might* mean a larger uptake. However, again, very strong family pressures are likely to prevent people taking up the offer. **We've now dealt with 57% of the world's population... You'd now need near 100% uptake in the rest of the world to reach your goal.** Let's go to the other extreme – **Western Europe and North America** (~14%) Views here are generally very liberal. I think we can assume that uptake would be largest amongst the young (mid-teens to mid 20s). Younger children hopefully aren't permitted to make life-altering decisions like species-shifting for themselves? Also once you move up the age brackets, views tend to be more conservative. So let's assume it's highest amongst 15-35s (~25% of UK population, probably similar across WE/NA). Initially, it's going to be a career-limiting move. Even if governments move to make discrimination based on species illegal, discrimination based on sex has been for decades, but most companies still have a huge gender pay gap. It's going to be hard to be taken seriously in a executive meeting with rabbit ears. Based on other discrimination issues, it's likely to take decades for it to become widely accepted. It'll also be problematic practically – in particular, any changes like tails or wings, or changes to basic skeletal structure (animal legs) will be hugely problmatic. As noted in your other thread, it'll cause issues for **clothing**. But also **chairs**. And **cars** – I won't want a tail if it stops me driving (or makes it difficult / uncomfortable). Modifications to cars – because of safety certifications – will take years. New furniture will be expensive. Similarly **medicine** – these new bodies might start healthy, but presumably they'll decay like ours. Medicine will take ages to catch up. Will I have to visit a vet to get my tail / wings looked at? Why is my fur/feathers dropping? I've got lice. Vets aren't licensed to work on humans in most jurisdictions. There's many jobs where it'll be impractical – a safety hat won't fit big ears; a tail will be a liability in a kitchen. Whilst some might give benefits (wings for couriers...?) the majority of tools and workplaces aren't ready to take advantage of it. Paws won't work a mouse and keyboard. And flight is likely to get legislation pretty quickly (think drone laws), due to risks (dropping your bag at 100ft and killing someone), and privacy fears. There might be compulsory registration – knife laws are pretty pointless if gangs have retractable claws. Every nation will consider how it can be militarised. With the increase of 'far-right' groups, one can quickly imagine "Keep Europe for Humans" marches (EDL, etc.). Short of actual lynchings, this will create social pressures against species-shifting. Let's optimistically say uptake in WE/NA, amongst 15-35s (where it'd be highest) is 10%. Let's say 5% across WE/NA. That gives you probably less than 1% worldwide uptake. More realistically, it's likely to be an order of magnitude lower for many decades, without some other pressure. **So... what could you do to encourage people to change?** To make people want to change in large numbers, you'll probably have to invent some **big** issue, like a disease epidemic which the new species (and perhaps some humans if you want to keep them) are immune to. Or large cash payments, or real-estate in the beastman world across the portal, etc. Or a food shortage – perhaps the new bodies are able to digest grass & leaves etc.? Sorry... that's all really negative! You might want to just skip your story forward a few decades to the point where uptake is now ~10% and starting to spike up? Or just set it somewhere like California or Vegas where uptake might be highest? Or start with a future world with widespread cybernetics & surgical bodymods which would be much more accepting of this offer. [Answer] Well, does the new body have any special abilities beyond physical boosts, like magic, flight, etc.? Because a ***lot*** of people would probably give up their human forms in a heartbeat if they could fly in exchange. ]
[Question] [ My facial skin is allergic to any fabric so I never put on a mask. My alter ego is called Stack Man. One of my special ability inherited from my Kryptonian dad is the fringe; this is the most amazing power one can ever dream of except invisibility. To keep a long story short, I want to uphold justice, while wearing my favourite cape and keeping my identity a secret, without wearing any headgear or mask. Is there a possibility, a way of manipulating everyone around me to momentarily lose the ability to recognize familiar faces, particularly my face? (Don't worry, my spider sense inherited from my surrogate mother—it's rather complicated—allows me to evade cameras! Use alien magic sparingly.) [Answer] Give them something else to see, like epic ear and nose hair. > > Moist had always been careful about disguises. A moustache that could come off at a tug had no place in his life. But since he had the world's most forgettable face, a face that was still a face in the crowd even when it was by itself, it helped, sometimes, to give people something to tell the Watch about. Spectacles were an obvious choice, but Moist got very good results with his own design of nose and ear wigs. Show a man a pair of ears that small songbirds had apparently nested in, watch the polite horror in his eyes, and you could be certain that that would be all he remembered. > > > (Making Money - Pterry) [Answer] [Prosopagnosia](https://en.wikipedia.org/wiki/Prosopagnosia) is triggered by a disruption to the processing of faces in the fusiform gyrus and temporal cortex. For induced cases, this is mostly due to the creation of lesions on the area brought about by trauma. But we're not interested in permanently harming people, just disrupting their temporal cortex... temporally... The fusiform gyrus occupies specific areas of the brain (see [this](https://en.wikipedia.org/wiki/Prosopagnosia#/media/File:Fusiform_gyrus_animation.gif) animation) and thus could potentially be targeted for disruption. Jostling the gyrus directly could disrupt the normal firing of neurons to either dampen responsiveness or increase random noise. Either option would have VERY interesting secondary effects, since that area of the brain is ALSO implicated in synaesthesia, dyslexia, facial hallucinations, and symptoms of autism. * ***Dampening*** the brain activity in that region would make it harder for people to read language, perceive color, or perceive emotions/communicate with others. * ***Increasing*** neurological activity in the fusiform gyrus could induce visual hallucinations, which brings me to my proposal... Your hero uses a carefully attuned infra-sound device that creates standing vibrations inside the skulls of everyone nearby. This defensive weapon excites the neurons in the gyrus, targeting the fusiform and surrounding lingual (encoding visual memories) and parahippocampal (memory encoding and retreiving) gyri. Basically, this operates as a temporary memory loss ray that protects your identity. The fun part is that with induced synaesthesia, villains have a harder time fighting you as their visual field is flashing colors due to the random tonal noises of your infra-sound. Basically, all they remember afterwards is random noises and a riotous rainbow... P.S.: Technically, setting up a standing wave to target the fusiform precisely is difficult since everyone's skull is a slightly different size. That's why targeting the surrounding areas of the gyrus is a better, more reliable strategy... [Answer] There was an episode of Dark Angel where a character in it was simply, easy to forget: <http://darkangel.wikia.com/wiki/Brainiac> People didn't notice him, or were quick to dismiss him (if you're not familiar with Dark Angel, this particular character was engineered that way). In one scene there's a squad of SWAT agents running right at Brain (the characters name) and still not noticing him. It's never explained in the show, except that he was engineered to be unnoticeable. The power of your character could be something similar. Or he could have a kind of psychic aura he can turn on at will. This aura makes the human brain unable to form the link from short term memory to long term memory when it comes to his face (or even things he's done) and so people forget him. Kinda like the Neuralyzer from the movie Men In Black. [Answer] The brain processes information on many levels. At lower levels lots of information is integrated and signal passing is mostly lateral, meaning that raw data that comes into our brains first goes through many parallel networks which share the responsibility of filtering out information that is recognized from the raw data and passing the compressed version, the unrecognized portion of the data (unrecognized at the lower levels), up to higher layers which are weighted to try to recognize the parts that were not filtered out at the lower levels. Basically what this means is that there is a hierarchically lower part of our brain that recognizes lines, curves and shading to delineate objects and start to find the field of depth and color. At a higher level those signals integrate so that more complicated features can be recognized such as an eye, or an ear, or a nose or a mouth - but this does not yet form a face, nor does it recognize it, but it is very close. At a higher level, those features integrate into faces. At yet a higher level the concept of a face is determined to belong to a person, but which person depends on what faces we have stored in our memories. New faces, like any other memory are stored in the context of the events that surround them. In other words we have a complex hierarchy of processing and spatio-temporal memory that leads to recognition, but there is a very *small and focused portion*† of the brain that does the work of taking all of the lower signals and forming a spatio-temporal memory of a face. This is because that process relies greatly on the part of the brain that recognizes an object (to the brain, at this point in the hierarchy, an object is just a small collection of signals from other neurons) as a face. If you can selectively disrupt that very small and fairly regular (across individuals) portion of the brains of observers, then you can hijack their ability to remember your face. My favorite way to do this, with a bit of clever technology, is called [Transcranial Magnetic Stimulation](https://en.wikipedia.org/wiki/Transcranial_magnetic_stimulation). This could perhaps be hand-waved to work as you need in your vicinity while in public. --- †By this I mean a small, perhaps pea sized region in the brain, which would be in roughly the same position in most people's brains. [Answer] I would say you can take also inspiration of [ForgetMeNot](http://marvel.wikia.com/wiki/ForgetMeNot_(Earth-616)) whose power is to be forgotten, altough he has no control over it and it makes him a bit depressed. Otherwise do you know [parfume](https://www.wikiwand.com/en/Perfume_(novel))? The hero has "no odour", and an extreme sense of smell, which he uses to create a parfume so people ignore him. [Answer] You could project a **Telepathic Illusion** that makes your face appear to look like someone else. Rather than being a particular image that you consciously project, the ability might function autonomously by projecting the image of whomever the person currently viewing you has most recently thought about, or some random aggregation of the facial features of various people they have seen before. While this does not *directly* affect memory, it can indirectly inhibit someone's ability to remember your face by displaying subtly different features each time they look at you. This has the added benefit of producing confused and discreditable eyewitness reports, since you will look different to each person, and should not expose any particular pattern of disguise that could be picked up on by a cunning investigator. [Answer] What you need is a [sexy](http://tvtropes.org/pmwiki/pmwiki.php/Main/DistractedByTheSexy) sidekick. [![Distractarella origins](https://i.stack.imgur.com/BSuZ5.jpg)](https://i.stack.imgur.com/BSuZ5.jpg) Source: [The League of Super Redundant Heroes](http://superredundant.com) Seriously now, this has been exploited by the likes of George R.R. Martin and his folks. In the Wild Cards series, there are at least two characters who grab everyone's attention to themselves wherever they go. [Succubus](http://wildcards.wikia.com/wiki/Succubus) and [Kim Toy](http://wildcards.wikia.com/wiki/Kim_Toy) had seduction related powers, and got to use them do distract people a few times (though in Succubus case, it was not intentional). [Answer] Do you ever open the fridge and look around, close it and then immediately forget what you saw? The mind tricks itself all the time. I have this amazing ability to forget names. It's like magic. I've met people who I have to immediately ask to repeat their names because there's something in my brain that just instantly drops it. It's hilarious when I drop it a second time even though I'm ready and trying really hard. It probably has to do with attention limits and some sort of weird social thing I'm doing when I first meet people. An illusionist practices this technique to exclude things from your attention (look over here while I hide the ball). I can imagine someone with the natural ability to apply a face forgetting nudge. Someone with the natural talent might not even be able to explain how it works. It could even lead to interesting situations where it doesn't work perfectly on everyone, or came into play by accident. [Answer] For a more primitive type of manipulation, have you thought of face-paint? It should bypass whatever allergies you have that prevent the wearing of masks or other headgear. It won't make people unable to recognize each other, but will interfere in their ability to recognize *you* - and it may be more ethical to tweak what people's eyes are seeing rather than than messing with people's minds by the hundreds. Because meddling with people's minds like that seems, invasive, and creepy, and inappropriate to me. So, there are three basic choices I can see in face-paint. You can go for an overall palette swap, tinting visible skin an varying shades of one color - or even a few, if you're willing to follow anatomical contours and be *consistent* about it - the basic idea being that you are "naturally" that color, so people won't be looking for or recognizing a human-colored version of those facial features. Or else you can go with the exceedingly subtle, which takes some studying and practice and a steady hand, and use the makeup to manipulate the eyes watching into seeing a slightly different face - through suggestions of light and shadow, slight thickening or thinning lines, shading and blending just a bit. The third option, less recommended, is the simple "I am wearing face-paint" option, where all that's needed is sufficient coverage - though this has downsides like being really obvious about hiding identity, and encouraging people to target or track the paint to find who's beneath it, and so on. The key to this attempt is *consistency*, of course, you need to convince people not only is that your actual face, but also that you wouldn't use makeup to hide it - so people won't be trying to smear the makeup, or wash it away, or be looking suspiciously at anyone who has makeup kits anywhere they go. The paint itself should be very subtle, thin and easy to wear since it needs not to smear (since all that's needed is a suggestion to misdirect the eye). There should be some paints or dyes which could be found or made that will not smear easily, or will only come off with the proper solvents, that can be comfortably worn long term - thick layers and moist paint (grease based) will be uncomfortable, but something light and dry will be wearable. Depending on how messy the fighting is likely to be, it might be wiser to tint or shape the civilian face, instead - as being less likely to get smeared or washed off in battle. The tinting would have to be subtler - but even a few shades of tan in the human-normal range might be enough to fool someone's perception, and the subtle facial feature shading should work either way...or even both ways, so an unexpected bare-face might reveal some vanity and the use of make-up, but maybe so not the other identity without the face-paint tricks to get to that face from bare. Shade the nose a little thinner, the brows a bit more arched this way, and rounder nose and thicker brows that way - and not only are your two faces further apart than makeup can *do* (since it really only needs to do half-way), but people would only ever be comparing your bare face to the face they expected to see, not any other faces that look kinda similar unless they've seen both, and bare-faced-from-both-directions, and also recently enough they can remember clearly to compare side by side. [Answer] The brain mechanism associated with facial recognition which is typically involved in prosopagnosia (face blindness) is very closely related to the mechanisms used for spacial orientation -- eg, finding ones way in a city. When one mechanism is disrupted so is the other, in most cases. Oliver Sacks wrote of having both disabilities, and I likewise have both. So to provoke face blindness in an individual one could conceivably provoke *disorientation* through some mechanism. But what that mechanism might be, I don't know. ]
[Question] [ Is it possible to build a clock that will be immune to relativistic effects on the passage of time? Can a clock exist that will always display the time of the place in which it was set? For instance, if we built the clock on Earth, then put it on a spaceship which accelerated away from the Earth at a significant fraction of the speed of light, the clock would continue to display the time on Earth. To observers on the ship the clock would appear to run faster and faster as the ship accelerated. Additionally, strong gravitational fields can change the flow of time. If our ship entered orbit around a black hole our clock would still compensate and display the real time on far-away Earth. The clock must be self-contained. It can't communicate with other clocks or otherwise observe the universe outside of it, but it can be as big and complex as necessary. EDIT: To clarify the capabilities of this clock: A clock that meets my specifications that was sent on a journey should display the same time as a clock left on Earth when it is returned to Earth. Further EDIT: This clock should match a clock left on Earth at all times and places. If the starship travelers want to celebrate Christmas on the same day as their families on Earth they should be able to using this clock. [Answer] **No.** In General (and indeed Special) Relativity, there is actually no such thing as "the time on Earth" from the point of view of a distant observer. There is also no such thing as "the place it was set". Relativistically speaking, the only things that make sense are *events* - which in non-relativistic terms, can be thought of as a combination of a time and a place together. The relationship between events depends on whether they are *timelike*, *spacelike* or *null* separated: * Two events are timelike separated if a massive object (such as a spaceship) can get from one event to the other without resorting to exotic things like wormholes or warp drive. * Two events are null separated events if only a massless particle (e.g. a photon) can get from one to the other. * Two spacelike separated events can't be experienced by the same particle or object even if it can travel at the speed of light. You can't send a signal between two spacelike separated events. A pair of timelike or null separated events always happen in a particular order, and everyone agrees on what order they happen in. So everyone can agree that event A happens before event B, no matter where they are or how fast they are going. However, people might disagree on the order in which two spacelike events happen. In fact, it doesn't really make sense to say that event A happens 'before' event B if they are spacelike separated. This means that if you leave Earth in a spaceship tomorrow, and you want a clock that tells you what the time is on Earth, you are out of luck! The 'time on Earth now' isn't a well defined concept. What you could potentially do is have a clock that tells you, for example, what the earliest time it could be on Earth when a signal you emit reaches home: the sending and receiving events are null separated, so you don't have a problem. You could also have a clock that tells you the time on Earth that you would observe if you looked back at a clock on Earth with an enormous telescope. [Answer] **Yes.** Though it's not *immune*, it's just *informed*. Luckily you have no limit on complexity or size, because it's not going to be simple or small. This isn't any kind of shielding, the time is simply adjusted given proper inputs. In the same way we would be able to calculate the effects from time dilation given the proper information about the system, like acceleration and gravity for each frame of reference, we could do that in 'real time' for a clock. If the clock is provided (or internally measures) the requisite information, it can calculate, within the precision of the information it's given, the time in a different reference frame. EDIT: BrettFromLA brings up a good point, intentionally or not, that measuring gravity and acceleration will muss with the velocity (with respect to Earth) measurements. The velocity would normally be measured by integrating the ship's acceleration with respect to time, but the acceleration due to gravity would be superimposed on those measurements. To account for that, careful measurement of all forces acting on the ship would be required. By tracking engine output, micrometeor impacts, radiation, etc; the acceleration adding to the velocity with respect to Earth's reference frame could be measured. In this way the clock, being allowed any size or complexity, could be considered as a gaussian surface around the entire ship. The measurements required would be only forces acting on the ship/clock. Clearly this is more complex than simply looking at an external reference, but it is still possible. [Answer] If you are in a spaceship that constantly maintains a line of sight to our solar system, you could monitor the red/blue shift of our sun, as seen from your ship. From that you can infer what kind of time dilation you are experiencing with regards to the Earth and correct the clock's time as you go along. This gives you the time of our solar system, as it appears to you. Then add to that time a year for every light-year that you have travelled. EDIT: I'll try to briefly explain red/blue shifting, because probably not everybody is familiar with these terms. The speed of light is constant, so when you move towards/away from an object, the light coming from it to you does not seem to change its speed relative to you. But it seems to change its wavelength in a predictable way in relation to the relative speed. When you split light coming from a star into a spectrum (like a prism splits it into a rainbow), there are gaps in the spectrum, which are characteristic of every star. By tracking how these gaps move towards the red or blue end of the spectrum, you can find out how much the light has shifted. [Answer] Would you be happy with something pseudo-scientific? **Quantum entangled oscillator** Similarly to how a quartz crystal's oscillation will provide a time signal for a modern watch, you could have some kind of quantum particle suspended in a field that causes it to oscillate at a very well-defined frequency. Then you'd need some mechanism to entangle a 'receiver' with the oscillating particle. This means that measuring the state of the 'receiver' gives you the state of the oscillator. Entanglement seems to allow instantaneous communication - meaning that the 'receiver' will oscillate at the same observed frequency as on Earth - meaning, it will get faster as the ship accelerates away from Earth. (although, I don't remember reading anything involving entanglement and accelerating frames of reference). It might even be possible to have multiple entanglements. This is actually probably not at all different to various ansible mechanisms that have appeared in other works. [Answer] ## A Broken Clock and a Black Hole Take a clock and throw out the battery. Now throw a black hole at the earth. Now time on earth is frozen, as [time does not pass in a black hole](http://www.phys.vt.edu/~jhs/faq/blackholes.html#q2). The time on the clock will match the time on earth. This solution, though it may require a lot of mass, is not very complicated. I suppose the criteria "If the starship travelers want to celebrate Christmas on the same day as their families on Earth they should be able to using this clock" is fulfilled [vacuously](https://en.wikipedia.org/wiki/Vacuous_truth) now. ]
[Question] [ I have found that, every time I try to make another humanoid species, they end up as basically just humans with extra abilities. For example, I tried making a race of dark-elves once, and they ended up basically as humans plus night vision and camouflage abilities. How can I make it that humans are better at some things and other species are better at other things? I can't take away the traits that are distinctively human (e.g. color vision, opposable thumbs, abstract thought and language, bipedalism) or else the characters will be hard to relate to and not easily able to interact with humans. So, in essence, **what are some human abilities that I could remove to compensate for the addition of new traits in other humanoid species?** [Answer] # Physical Abilities You can start by looking at how humans could differ physically from other races: **Running** Humans are good at running long distances without getting tired, especially in the heat, where it has been argued that there is no creature on earth better at running long distances than humans. Early hunters used this ability to get food by chasing animals until they were too tired to run anymore. (This is called persistence hunting) **Size** Humans are pretty big, when you compare them to most other animals on earth. What if the other races in your setting are mostly the size of badgers or chimpanzees? **Senses** While there are examples of animals that are better at sensing than humans in pretty much every way, human senses are still quite accurate. Other species may not share this trait. For example, humans have trichromatic vision and can see accurately both nearby and far away. This gives humans a big advantage in noticing camouflaged creatures and in noticing fine detail. **Manual Dexterity** Most other animals don't even come close to humans in this regard. Other races may have paws or talons that are evolved more as weapons than humans, but can't pick up and use a spear, or they may have somewhat human-like hands, but no opposable thumbs. # Mental Abilities The biggest difference between humans and most other animals is our brains. Other races of humanoids, even ones that have evolved to use tools like humans do, may not have the same mental abilities that humans do. **Learning** Humans are really good at learning. Way better than anything else we've encountered on earth. Other humanoids may take significantly longer to figure things out than humans do. **Language** Humans have developed and can comprehend some incredibly complex languages. Most other animals don't do this. A different humanoid race may have to learn everything by example, as many other animals do. **Tool use** Lastly, consider that humans have evolved first and foremost to be excellent tool users. We create, improve and use tools on a regular basis. We manipulate our environments through terraforming. We build roads and tame animals to serve as beasts of burden. A race of stealthy night hunters may have never had the need to even think about domesticating a horse or farming wheat, which are cornerstones upon which human society has been built upon. We may not be able to see in the dark or match our surroundings, but that's because those traits aren't needed when you have walls lit by torches and manned by archers. Our manual dexterity, learning, and language abilities have all risen around boosting our ability to manipulate our environments and make up for any shortcomings through use of tools. Bear people, while bigger, faster, and stronger than humans, may have none of those things. They may use primitive spears and make clothes, but tools are our *specialty*. This is probably the most unique thing that divides humans from other animals, and could well divide humans from the other humanoids in your world. [Answer] If you consider writing the hard and unpleasant details, Homo Sapiens triumphed over the other ape species by four (although not exclusively those) characteristics: 1. **Being able to lift his arm over his shoulder**, enabling to hurl things wider and with more smack, thus outperforming those apes who could only hold stones or antilope leg bones to smash craniums in. 2. **Being able to eat anything** Homo Sapiens ate and does eat anything that isnt poisonous or runs away fast enough from him. Early forms of Homo Sapiens also practised Cannibalism, although that fact is hardly popular when encountered in a story. Nevertheless, that unlocked sources of protein for him that might otherwise have been untapped, allowing for his immense growth of brain matter, which requires lots of energy to run immense parallel computing processes, a growth that was only hemmed in by the size of the birth canal in the females, as bigger head circumference due to bigger brains increased the difficulty and mortality when giving birth exponentially. 3. **Being able to walk long distances** this enabled Homo Sapiens to not having to rely on his motoric skills to get protein, he would simply walk to the next carcass that another predator had slain and eaten from, leaving a lot for the all-eating Homo Sapiens to feast on. Due to his other skill he was fairly able to hold off other scavengers until he had eaten his fill. 4. **Ability to withstand hunger** Homo Sapiens is incredibly adapted to withstand long periods of hunger without detrimental effects. There is even a backup system built into Homo Sapiens, which switches from sugars when not available to burn as fuel for the brain to ketones from fat. As a last resort when those are used up the body of Homo Sapiens will start using up the protein of the muscle tissue to maintain brain function. During all that time he might be getting progressively weaker, but the whole process several weeks to be coming to its terminal end, during which time finding even minute amounts of food can switch the body back onto a more normal functioning. **Removing Traits** From this base onwards, all characteristics of modern humans, such as the ability to speak, learn, remember or conduct creative thinking processes might be removed. His motoric skills might be reduced to the level that he is unable to even produce pottery. As for the higher planes of existence and intelligence, Mathematics provides the ultimate Lingua Franca between the different species, as the Laws of Nature in the Universe can be notated (and one would assume all intelligent species start notating them sooner or later) in it. Here Homo Sapiens will have his own unique approach, which distinguishes him from other species. His approach to Physics might also take a completely different route. Modern Humans for example have developed Nuclear Technology and experiment with Nanoparticles and Solar panels. But another species is perfectly conceivable that diverges from this trunk and after the basic technologies like lighting fires switches to produce engines powered by phase impedance instead of rotating magnetic fields, and employs micro-miniaturized semi-intelligent swarms of particles which combine to produce gigantic magnetic fields to neutralize enemies, instead of going the conventional weaponry way of Homo Sapiens with all his guns, explosives and armour. Branching the tree of technology might be the key calling feature in distinguishing the species as you intended. If that is not the way, the acts of taking in nutrients to keep life processes functioning and the removal of waste products from the body, its physical movement around in space and its interaction with the same of its kin are universal to intelligent beings similar enough to humans to be recognized as such. They might have advantages in performing those tasks in certain worlds under certain conditions (like Homo Sapiens in the Grasslands of Africa had in his) but would also experience and encounter tradeoffs due to their specifications (as Homo Sapiens encounters with his brain size impeding his ability to give birth fast to a large number of offspring). [Answer] I dislike the general perception that other races are exactly human plus a few traits. Humans developed in a very social environment and we have several traits that reflect this. Physical We do have a few physical advantages. * Human endurance is unparalleled in the wild...our skin, muscle, and digestive 'fuel use' is all optimized to keep us going extended periods of time. Admittadely in most foot races, we are the tortoise to the horses 'hare', but over a drawn out period of time we will out perform them in a foot race and easily chase them down. We are also well adaptable to nearly any climate this earth has to offer. * Size. We are decently big creatures and are trending to bigger as our diets and lifestyles change. There is a good possibility a distant generation of humans will average 8-9 feet tall. * manipulation. The degree of accuracy we can achieve is quite impressive when you compare it to the generally twitchy movements of many other creatures. Social If you are making a 'monster' or 'loner' race, this will truly set us a part. We evolved socially, with social dependence being a driver of the evolution of our intelligence (EI, my ability to survive is as dependent on your intelligence as it is my own). When developing another race, this social trait is lost on an individual...on the society level you will see how this helps us thrive. * Communication and expression. The number of distinct concepts we can communicate via speech or body language is extreme and only seems to be growing with time. Not only are we good at expressing ourselves, but we're pretty adept at picking out very subtle signs in others denoting what they are thinking and what motivates them. * Deceit. Goes hand in hand with above, but we can become incredibly good at misdirection and hiding our true intent. * Specialization. This really requires the social aspect to develop...if I can fully rely and trust my existence on others to provide things such as food, shelter, and basic necessities, I have no need to know how to make and create this myself and can dedicate myself to other specialized roles. A member of a 'loner' species will be forced to provide all these things for themselves (jack of all trade)...and although the 'loner' race can become adept at a metal working task, they will never reach the skill a master blacksmith dedicating 8 hours a day every day to the perfection of their craft will. The urge for people to pass on their experience to the next generation seems just as ingrained in us as our desire to have children * Compassion & Empathy - Humans can detect the feelings of one another. We know when another is feeling secure as readily as we know when they are feeling anxious. We can feel what others are feeling and sympathize on a level that very few other species seem capable of (I'm not going to say it's unique to us as I swear my dog does this too). This adds a unique tie between us, although not all of us, most will step in when they see another human in trouble or suffering injustices. And to go along with it, there is a rewarding feeling provided to us by our brain for doing so. Once again, a heavily evolved social trait of humanity that strengthens our society. * Spirit of one. Despite our individual nature, we still crave to be a part of that greater social whole. As the Spartans would say, "it's the noblest and safest thing for a great army to be visibly animated by one spirit". It's also the most unnerving to be on the other end seeing the united one approaching. These social trait, although perhaps not so helpful on an individual scale, allow to create the huge dominating cities and collectives we have here on Earth. To me, it's quite questionable that a species lacking in thee social evolutions can create cities and cooperation between them to the extent we have. Mental We are strong creatures on a mental level as well, and part of this is very heavily dependent on our social nature * Learning. At a young age we are a complete and utter sponge. There is absolutely no need for us at a young age to be anything less than fully dependent on others, so the mind has no need to focus on anything beyond growth. I've heard speculation of the brain containing an 'early language acquisition device' as one of the few ways to explain how readily we can catch onto language, just from exposure (and then loose access to this ability as we age). And this device is impressive...you can learn grammar concepts without ever being aware you've learned them, and learn them from people who are unaware they are using them simply by listening to them. Given the right environment, there seems to be little we cannot understand * Willpower. Average people are decently solid here. In a trained human, it's amazing the extents we can push ourselves and what we can endure, and emerge stronger from the experience, not weaker. Poor odds of succeeding is not a reason to give up, it's a reason to go further. * Creativity. There's always more than one solution to any given problem and although just one of us might be capable of finding only one solution, 20 of us will create a wide variety of solutions to the problem. * Individuality. All humans are unique and the various combinations of uniqueness further spread our ability to specialize. This individuality just goes to enforce how well this 'specialization through socialization' trait is ingrained into our species added: It's hard to differentiate some of these items by category. For example, our ability to by inspired through others inspirational stories shows how ingrained our mental capabilities are defined by our social nature [Answer] If you want the humans to be better than another humanoid race you have to take something away from the others. Say elves, often they are very fast and agile, to be more agile, they would be lighter and have lighter bones and muscles. So that would be why the might be fencers and archers. Humans are slower but stronger and can take a hit better. A human could do real damage to an elf in an 'even' fist fight. Dwarves tend to be very solid, strong and short. Humans have the height advantage, and where the elves are faster than the humans, the humans are just as agile compared to dwarves. Have a lizard race the loves the desert, can handle long periods without water, hot sun isn't a problem, can eat once a week if needed, but has no tolerance for cold, and can't function well in the middle of a cold desert night without help from a fire or special cloths to contain their body heat. The trick is for each ability, you need to give a 'handi-cap' or you just make humans fodder for the 'better' races. If a race can see great distances clearly (like a bird of prey) then they might be basically blind at night, Great night vision? Colorblind. [Answer] I think your choice should mainly depend on the medium you use. If it's storytelling (in person or or by written word) I think it's best to concentrate on mental abilities, culture and behaviour. In case of pictures (comic books, artworks, movies) focus on physical traits or looks. Why is that? When you write or tell, you usually describe how somebody (or some species in general) looks like once. You may use some of physical traits later (using phrases like "he moved his scaled hand", "her blonde hair were in a state of grate disarray"), but if you overuse them you'll slow down the action, and if you don't, your audience will forget about them and concentrate on important stuff. On the other hand, you describe someone's thoughts, motivations and actions very often, because they change as the story progresses. In case of graphic medium, the situation is quite opposite: your audience will see your characters all the time, watch their actions, but never hear their thoughts. There also rarely good moments to go in details about cultural differences. Unless you'll state otherwise, I'm assuming you are writing or telling, so I concentrate on this angle. Several examples: Possible differences in mental abilities: * Humans perform very poorly in being rational (but we are great at rationalizing!), we often depend on intuition, instincts and emotions. In a lot of fantasy and sf stories you will notice races who are rational and emotionless, so it's easy to tell them apart from humans. You can also take an opposite approach, push it to extreme and invent a race which is unable to remember anything (making rational thinking impossible), but balance it out but superb instincts (or even precognition) * Some humans are loners, some like crowds, but most feel best in small groups (tribes), but we are all individuals, with different backgrounds and personalities. You can push it to an absurd in both directions: create a hive, where everyone are the same, think the same and act the same, or a society of loners, where they meet only once a year for procreation and try to kill each other for the rest of the time. Depending on your story any of it can be an advantage, a disadvantage, or neither (just a difference) * We are creative. We have fire, Internet and nukes. For the most part of our history, great discoveries were the result of one bright idea which came to one bright individual. Only now you need huge lab, huge r&d budget and hundreds of people in white coats to invent anything. But you can make a society, which worked like this from the beginning - instead of relaying on geniuses it utilizes cooperation of hundreds of highly skilled individuals to advance (skills may or may not be connected to biological differences between members of society). Once again, it can be an advantage, a disadvantage, or merely a difference. Possible cultural difference (I'm assuming, that you took none of the ideas above): * Whether we like it or not, the moment you put two complete strangers in a room, the starting forming a hierarchy. A simple one, but a hierarchy nonetheless. How about some anarchic society, where everyone are truly equal, because nobody WANTS to rule? * Most human cultures have similar set of basic rules: don't steal, don't kill without a good explanation, etc. Make up some bizzare rules, and then come up with biological reasons why they work (like no reason for "don't lie" rule, because everyone can see their brain activity via transparent scull and can see when you do that) If you really want to use physical attributes, I may suggest some of those: * Diet. Most answers here are explaining why is it important. I'd like to add, that a lot of our customs, traditions and even laws are related to diet, so please take it under consideration while making decisions. Example: in our world pigs carry a lot of dangerous parasites, so some religions are forbidding eating it (even though we've made it safe by now). Similar outdated laws are pretty much an instant subplot. * Regeneration abilities and immunology system. This played a major part in human history, just ask Aztecs if you don't believe me. On the other hand, we have only two sets of teeth, and they are quite fragile when you think about it (for something so hard that you need a diamond to drill through). How about a species, which can regenerate lost limbs, but cannot fight common cold? That's of course a very simple idea, you can play with those two endlessly. * Armour. We have a nice ribcage, strong skull, and that's about it. Very little protects us from physical harm. Have you thought about armadillo-people or hedgehog-people? Depending on how far you go, the difference may be only visual (because they evolved to softer versions of their invulnerable ancestors) or practical. I hope that it'll help.Good like and have a lot of fun. [Answer] If we're talking about new races with different specialities, but are still fundamentally humanoid, probably with a common ancestor somewhere in prehistory, then the most important thing to consider is *compromise* between traits. If, for example, we have a night-active race, what would it have to gain to be successful in that role and what would it lose? Most likely it would have excellent night vision, and probably better hearing, but as a consequence, it would probably not see as well during the day, it would be more sensitive to loud noises, and it would probably be easily burned in the sun. This race may even have colour vision *at night*, but as a consequence, have poorer or even *no* colour vision during the day (one or more of the cone cells in the eyes become rod cells, but retain the particular pigment). They may gain a tapetum (a shiny layer behind the eyes that doubles the effectiveness of night-vision), but as a consequence, their eyes will reflect light, making it easier for light-source bearing daylight dwellers to see the night-dwellers looking at them in the darkness. Another example is physical strength. This can be achieved in two ways - the first by increasing muscle mass, which as a consequence leads to an increased need for food. The other way is by adjusting the lever ratios of the muscle attachments - moving them further from the joint makes the limb stronger, but reduces the speed with which the limb can flex. Taken in the opposite direction, a limb can be made to flex faster by moving the muscle attachment point closer to the joint, but with the consequence that it does so with less strength. Whatever you *add* to your hypothetical new race, just keep in mind that it will come at some sort of a *cost*. It is your job to see that this cost is not so extreme that it would cause the race's extinction, yet significant enough to keep things interesting and realistic. Another, related factor is psychology. The psychology of a species is fairly intimately tied up with its physiology, so if you change something physical, you will get a corresponding change in psychology. For example, our hypothetical night-dwelling people with colour night-vision and an eyeshine would probably go about at night quite boldly, and though they may still be afraid in pitch darkness (if they don't have IR vision), they would be more likely to be afraid in *daylight*. A stronger race would most likely think in terms of strength, while a faster race would be more likely to think in terms of speed. Human psychology is *very* strongly bound to the specifics of our reproductive system. As a species that is almost unique in being able to engage in sex at any time, this places an incredibly strong influence on our psychology - as adults, we think about sex a *lot* compared with other species. If we were to alter the exact nature of the reproductive system, very different societies would arise. What if the new race went into heat for only a few days each month - or each year - and was disinterested in sex at other times? What if the new race was more like bonobos, and sex was as ubiquitous (and had much the same purpose) as a handshake or a "hello" has in our society? What if males could also breastfeed infants? What if males - or females - were significantly more common than the other gender? [Answer] There are several standard "human" traits I have seen in media that portrays multiple humanoid species, and they tend to balance humans on an appropriate scale for the writer's needs; some delve into their inferiority to other races, while others push them to superiority over humanity. I'll touch on both, because some people look for one over the other. ## Humans are diverse. Look around you, you will see races of humanity specifically evolved for the climates in which their ancestors developed. Life all over the world went through evolution like this, but it's possible that humans are (in your world) the most widespread of any humanoid species, or perhaps the least! Often we are portrayed as the "adaptable" sort, capable of surviving against all odds, regardless of the environment, because we have a willingness and a physical form built to adapt to our surroundings. That could be an advantage, if other species lacked that ability. People come in all shapes and sizes; what if humans were larger than other humanoid species, or other species were smaller? That may give them advantages in strength and speed. Then you can go into population; humans may have a larger/smaller population size relative to other humanoids, based on your needs. A culture/species can be steeped in traditions of many kinds, and these can be a hindrance; an unwillingness to grow and adapt to a changing world can leave a culture behind while others rise to untold heights, eventually sweeping those that lag out of the way of progress. Humans tend to, overall, change with time. Ancient cultures eventually fall apart, and others rise up in their place. Even today, we see the remains of old empires still alive, but it is clear that (some) changes have occurred to keep them alive in our modern world. ## Humans have a sense of community. This is (sometimes) very obvious, though not always the case in larger centres. People readily join together to accomplish a larger goal, resulting in some impressive feats in the past. Small communities construct buildings together, look after one another in times of hardships, help defend one another; numerous empires have been brought down when the people decide they've had enough and all act as one, showing the effects of a larger community. If other humanoids lack this sense of "oneness" it could hinder their growth as a society, increasing the enmity between other members of their species. ## Humans can resist disease. Diseases can bring down any population, it's a fact that comes with being alive. (A virus can bring down a robot1 just as easily as another virus can bring down an organism.) At the same time, our immune systems are very effective. Other species of humanoids could be more easily affected by disease, resulting in a fear of becoming ill, a social stigma against any form of sickness. ## Humans can be barbarically aggressive If another humanoid is not as war-minded as humans are, they may not be at all capable of defending themselves if a would-be conqueror decides he likes their land. Whereas humans would often fight to retain what is theirs, other species of humanoids may in general just run away from conflict, losing everything quite easily. What if a species is even *more* aggressive than humans? Other humanoids may be more likely to rise up against them; that aggression has become a weakness. They may even be so aggressive that the species is too busy tearing itself apart to worry about any form of social growth. 1Let's not argue about robots being alive. [Answer] I can think of a few: * Hearing * Stamina * Smell * Abstract Thinking/Reasoning, Emotions (think Vulcans) * Extra long/short limbs which would come with their own strengths and weaknesses (short: can easily maneuver through tiny places; long: Good for keeping watch) * Have a magnetic field around them which affects all objects around them and thus the way they perceive/interact with the world. * They do not have mouths and instead feed on bacterium that enter through their nose, and communicate telepathically. * They are exactly like humans except that they have a bee-hive mentality and communicate solely as groups. * They are exactly like human except they don't know or understand the meaning of community. [(Wolf, Jackal, Fox Scenario)](http://qr.ae/lGkG1) * They are so affected by sudden sounds that it causes them to lose their balance for a few seconds thus putting them off their guard. You've mentioned that you want them to have 'distinct, yet equally useful' abilities. I think that with any ability there are drawbacks. For example: * sharpened hearing would be very useful in some scenarios, but extremely annoying in loud environments. * If you're giving them night vision, you could take away a bit of their regular vision (cat-like). [This](http://www.journalofvision.org/content/7/12/6.full) article is an interesting piece on how our vision affects our perception of sound. * Our ability to adjust to our surrounding is incredible.Consider the [Moken sea gypsies](https://www.youtube.com/watch?v=YIKm3Pq9U8M) who can see underwater. So if you're giving them extra abilities, what caused them to have to develop those abilities? This might also indicate which traits they were less likely to fully develop, once you consider their environment. [Answer] Your premise is faulty. Truly alien races can still be understood by your audience if done well. Look at Vernor Vinge's "Fire upon the deep" book where there is a race of canines which telepathically join as packs to form one intelligent organism. Or the sequel which has intelligent spider like entities. We are familiar with bipedal, largely human-like beings because it is easy for writers and because it is easy for the effects department of movies and TV. This is finally starting to change with modern computer generated characters. Here on Earth the whales and dolphins were once land dwellers. There is all kinds of variation in sea life. We also have fantastic bugs on land. There is always the question of what if the being was not carbon based. As for balance, why would there be? If the beings are all from the same world which they share with humans you need to explain their origins. Did another mammal species also form intelligence? Or perhaps a lizard did? The they are from multiple planets and never had to compete there is no reason for balance. The people of Jupiter II may just all look like the most amazing size 2 models while being able to bench press cars and live 300 years. ]
[Question] [ So I have a really long space-flight section of my story with all necessary requirements for preserving the crew is in place (hypersleep etc.) But one thing went into my mind with preserving other necessary products like food and best of all... Medicine. All medicines have expiration dates, From regular cough syrups to antibiotics. Pure sugar like Dextrose, Carbs like Glucose and electrolyte packs. Is there a way that we can "preserve" medicines in a long space-flight? How would it be stored and how would it affect the medicines quality if so? Are there limits? [Answer] **This requires a combination of approaches** Medicines and their components vary, so your spaceship will need several approaches to preserve them all. 1. First, knowing what a real expiration date is vs a "Please throw this perfectly good item out and buy a new one" date is important to know. A pack of pure sugar isn't going to rot if it's stored in a cool, dry place with a reasonably air resistant lid, but don't try this with a banana. 2. If a medicine is made from multiple components, storing each separately and making the medicine when needed can also help in some cases. Knowing the manufacturing methods of each component will also allow some of those to be brought along as more easily stored sub-components. 3. Separating the medicine (or components) into smaller sub-packages is a good idea. If 5 kilos of the very important "Medicine Component A" is more than enough for your mission, a single 5 kilo cannister could spill, get lost, or get contaminated. A pair of 2.5 kg cannisters stored in 2 separate areas of the ship, each containing multiple smaller packets, will greatly reduce the risk of losing it all to a single unfortunate incident. 4. Dehydrating or freeze-drying can greatly extend the shelf life of many materials. 5. Most items last longer at lower temperatures, but are a few that can't handle freezing. For those that can, colder is usually better. Interstellar space is VERY cold. If this is an in-system mission, shaded areas in space are very cold. If you land some place like Mars, a -100C freezer is a good thing to get installed quickly. You also mentioned food. Much of the above applies to food, but there food has a major complication beyond chemical components in medicine, bacteria. Aerobic and anaerobic bacteria are the bane of long term food storage. Canning (really just boiling and sealing up away from bacteria and oxygen) was a big step towards reducing the problem, but isn't perfect. Check out shelf-stable milk an military rations. Those are typically done with ultra high temperature processing and the containers are multi-layered to keep out oxygen. A more effective method to sterilize food is food irradiation. One of the drawbacks of the irradiation process is that vitamins also get degraded to some extent. Because of this, if irradiated food will be a significant part of the diet, vitamin supplements become a very good idea. [Answer] ## You already answered your own question, whatever hypersleep is. Put the medicine in whatever the people are put in, if you have the technology to preserve a living human body indefinitely storing simple biological compounds should be easy. a human body contains millions of different biochemical compounds, if the tech can preserve all of those insitu then there is no biological compound they cannot preserve. [Answer] ## The biology route: Medicines come from a variety of sources. Most of them organic. At least 118 drugs are based on natural sources: 74 percent come from plants, 18 percent from fungi, 5 percent from bacteria, and 3 percent from vertebrate species such as snakes or frogs (Ecology Society of America, 1997). Vaccines are also made using organic material. So, instead of carrying around large amounts of perishable medicine, why not take the primary producers with you? If plants are your primary source of medicine, then you only need the seeds of those plants. Seeds in good condition and stored properly will last at least one year and, depending on the plant, may last two to five years. The plant that holds the record for the longest dormancy is a lotus that was sprouted in 1995 from a seed that radiocarbon dating estimated to be a whopping 1300 years old. Store all kinds of seeds, then plant them to replenish the stocks every few years. This way, you only need to have one or two plants growing in the ship at any time. Bacteria can also be used in the same way, and unlike plants they multiply orders of magnitude faster. Gene editing can also be used make the whole system more efficient. Fewer species to store among other things. [Answer] **It's possible... in a sci-fi setting!** [![Honey](https://i.stack.imgur.com/mHmNw.png)](https://i.stack.imgur.com/mHmNw.png) Now, you must have felt weird seeing honey here, but hear me out! When you asked for something that doesn't expire, two things came to my mind: honey and salt. They're not medicinal but they are my answer to your question. Hopefully, you are open to new sci-fi ideas. **1. Synthesizing Honey-like Chemicals** But first, I have a request to tweak some of your rules to your sci-fi setting. Add something like "Company A discovers a method of making lab honey!" Then "Behaviour of Hostile Environment for Microorganisms can now be transferred from honey to chemicals possible!" Long story short, your sci-fi has the technology to imitate honey, because honey doesn't expire, and that's what you are aiming for. Take note of these factors that make honey... immortal! One. They **contain extremely low amounts of water**. Microorganisms need water to survive, and medicines aren't known to contain water so feel free to ignore this detail. Two. Honey is acidic. Microorganisms just won't survive in an extremely acidic environment with few exceptions of course. The optimal pH level for microorganisms to live is somewhere neutral, ranging from pH 5 to 8, and acids are less than 7. That being said, alkalines are higher than 7 and are also not safe for microorganisms. In summary, your medicines must be **either highly acidic or alkaline.** There is one contradiction though. They are not safe for consumption. You gotta do some magic like dipping them in an additional acidic or alkaline component that doesn't mix with them but can be combined and completely separated afterward just as how not all solvents are compatible with all solvents. Or turning medicines into highly acidic or highly alkaline first then adding a solvent to increase or decrease their pH levels to their safe level for human consumption. It is up to you! Third. It's not a matter of scientific reasoning but mere intuition only so don't take this seriously. They are **in liquid form.** It always bugs me why honey is liquid. It was never mentioned at all but I believe it's the main factor as to why it doesn't expire. So you gotta turn your medicines from solid to liquid form which is a contradiction from the #1 which is extremely low amounts of water. Thankfully, water is not the only solvent, but you have to think of yet another universal solvent for this. **2. Not all medicines are ingested. Some are for external use only.** [![a room for salt therapy](https://i.stack.imgur.com/4XvPw.jpg)](https://i.stack.imgur.com/4XvPw.jpg) This answer doesn't require the magic of modifying your world settings, but one that doesn't suffice your demand for a mystical ingestible medicine. Long story short, external medicine cannot expire. Salt, alcohol, bandages, and guess! Honey! Unfortunately, such items are limited and so are their applications. **3. They don't expire. They die though.** [![Bacteriophage](https://i.stack.imgur.com/yrZdv.png)](https://i.stack.imgur.com/yrZdv.png) Okay, this is my worst answer because I'm just finding a loophole and ignoring the point of "unlimited shell life". Yes, you fight fire with fire, using a virus to fight the bad bacteria and cancer cells, and it's a thing! You don't need to tweak the rules of the world but the said bacteriophage is only experimental for now as we speak, so you might want to add something like " We managed to program viruses for our cause of curing cancer! No side effects! Promise!" And "Authorities of Health warns pharmaceuticals of unpredictable viral mutations." Long story short, these alive medicines do not have a shell life, just a demand of unlimited food. [Answer] ## Basically, you can't. If the spaceship required a store of medicinal compounds for treatment of various problems the crew might have, short of using whatever super freezing method they use on the crew themselves or having entirely new treatments for illness that don't require our current hodgepodge of medical knowledge, the spaceship's AI would require an automated laboratory and a greenhouse as well as large stockpiles of certain basic chemicals and substances, to maintain a store of finished medication (a pharmacy) at all times. So it would need energy and labour to have this maintained, the labour likely provided by automation and/or robots, the mental labour by a computer, and the energy by whatever energy source the ship uses - antimatter reaction or fusion are the most common two in SF. Now it's certainly possible to have medicine that effectively 'never' loses potency, and some modern treatments involve substances like that. However others do chemically lose potency over time for various reasons. With more effort in production, that length of time could be lengthened, or even circumvented. But for a fully stocked pharmacy of *today's* medicines, you would need a production facility on the ship that continuously produces and replaces (and recycles) them. ]
[Question] [ I'm creating a continent for a story I'm developing. I was just wondering if this map looked realistic from a geographical point of view (weather, city placement, environment, etc.)? Thanks for any help you can offer! [![enter image description here](https://i.stack.imgur.com/MaYQN.jpg)](https://i.stack.imgur.com/MaYQN.jpg) [Answer] **Not sure about the towns** [![enter image description here](https://i.stack.imgur.com/2c2iB.png)](https://i.stack.imgur.com/2c2iB.png) This guy is in the middle of nowhere. It should have at least a river as a source of fresh water. Even then that doesn't justify having a large city here, even if there was a resource cite here, like an iron mine. There is no way to transport that resource anywhere nearby. Xavon Wrentaile suggests Far Reach might be an import site. If there is another land to the West, with exotic goods in demand in Tomein and New Aerith, then Far Reach is the ideal place to import them. You have to take the goods through the mountain pass, so might as well land your boats as close to the pass as possible. There are still difficulties: (a) Lack of fresh water for drinking and farming. Might not be as much a problem if the sea brings a lot of rain for the plants, and you can build wells. Feel free to add a river to a map to remove any confusion. It would help if the river went through the mountain pass as then trade caravans can use it for drinking. (b) Bad transport links. The only way to bring goods to Tomein and New Aerith is walking. So I suggest the imported goods have a high cost/weight ratio. For example these yummy guys: [![enter image description here](https://i.stack.imgur.com/hHsQZm.jpg)](https://i.stack.imgur.com/hHsQZm.jpg) This guy is also in the middle of nowhere. [![enter image description here](https://i.stack.imgur.com/bpuxs.png)](https://i.stack.imgur.com/bpuxs.png) Why do people live here? It would make sense if they mined something in the mountains, and there was a river connecting it to the cities to the southwest. [![enter image description here](https://i.stack.imgur.com/PFhDr.png)](https://i.stack.imgur.com/PFhDr.png) These guys look like military outposts. So the lack of water or transport is not so much an issue since they don't have many people living there. Perhaps the fortresses were built to guard the spice trading route from Far Reach? Spices are prime targets for bandits since the high cost/weight ratio makes it easier to steal spices than iron ore. [![enter image description here](https://i.stack.imgur.com/pNa47.png)](https://i.stack.imgur.com/pNa47.png) These guys are good. I wonder what is the political situation since they all live on the same lake? [![enter image description here](https://i.stack.imgur.com/3kYHM.png)](https://i.stack.imgur.com/3kYHM.png) It makes sense that no one lives here. There are two places for towns at the estuaries. But they would be small since there is no large source of wood. I also figure the "Windy Plains" is battered by coastal winds and it is hard to grow stuff. This makes the sea rougher than the Southern oceans, which are sheltered by peninsulas. So it would be hard to trade with Carnheire -- still far away -- by boat. Trading by land is a no no since the Eastern coast is isolated from the rest of the continent by two mountain ranges. Maybe chuck a few Wizard Towers down here. [![enter image description here](https://i.stack.imgur.com/SZXIu.png)](https://i.stack.imgur.com/SZXIu.png) The location is remote so no one will bother the wizards. Of course the towers are invisible so do not appear on normal maps. [![enter image description here](https://i.stack.imgur.com/tuOvL.png)](https://i.stack.imgur.com/tuOvL.png) I'd expect three cities here. They can trade with each other using boats. The one on the left might have mines in the northern mountains which are conveniently close. Send the ore down the river and then maybe to the other two cities. [![enter image description here](https://i.stack.imgur.com/BpaI7.png)](https://i.stack.imgur.com/BpaI7.png) Same for this place. Good place for a city. [![enter image description here](https://i.stack.imgur.com/a6bzl.png)](https://i.stack.imgur.com/a6bzl.png) Think about putting a town here. This is where their wood comes from. [![enter image description here](https://i.stack.imgur.com/HM9UG.png)](https://i.stack.imgur.com/HM9UG.png) Maybe put these guys closer to the forests to make clear their main industry is logging. Politically I'd expect two main powers: [![enter image description here](https://i.stack.imgur.com/EURdX.png)](https://i.stack.imgur.com/EURdX.png) The red guys and blue guys both have their own sources of metals and wood. So they can be independent of each other. The green guys are their own place because the forests are hard to walk through. [Answer] I don't get many of your city placements. Cities tend to grow for a reason and they need good natural supplies; typically including some non-salt water in the form of a lake or river, food (fish or hunting), and in strategic locations. That is why they line rivers and coasts, and are seldom isolated inland without at least a lake. One strategic reason is a port in friendly seas; I'd expect a large town on that river that flows through a forest into the southern gulf; that's a trifecta of food sources, fresh water, and travel by boat on the river or sea, it would probably be largest city in this world. There's another on the west side, south, a little gulf with a calm inlet near a forest and lake. Natural features are what tend to define trade routes and where people live. You don't seem to be exploiting them much. You do have towns around the big lake, but you'd likely have towns and farms just lining all these rivers, that's where the arable land is, and rivers provide drinkable water, fish, plenty of water for bathing and washing stuff, and human waste disposal (don't forget that). They also may supply underground water for wells; those aren't everywhere. Then because of those towns, you expect roads to form, linking them and following the river, for northbound travel. Again, travelers follow the river both with and against the flow; for the water and the hunting alongside it. [Answer] For starters your map is very beautiful. I kind of feel like I am saying: "Yeah she is pretty but her teeth are kind of crooked". If you like this map for your story, roll with it! And nice work. Here are 2 ideas. 1. Discontinuous mountain ranges. I like where your mountains continue into the ocean. It seems a little strange to me where they stop and restart with a different name, like the streets in Atlanta. [![mountains](https://i.stack.imgur.com/Aau0f.png)](https://i.stack.imgur.com/Aau0f.png) The plate interaction that put up the mountains on one side would probably be the same plate on the other side. I like to think you have the low place between for story reasons. Maybe have there be a mountain pass? 2. Rivers. A lot of your rivers fall off the side of the land like they were falling off a cliff. [![rivers](https://i.stack.imgur.com/cvLBi.png)](https://i.stack.imgur.com/cvLBi.png) Think of why the river is where it is. That is the lowest land. And the river is going to make it lower. The ocean will probably come in to meet it because that is the low point of the land. Take a look at the rivers that empty into the Chesapeake bay. [![chesapeake bay](https://i.stack.imgur.com/ZrnGk.png)](https://i.stack.imgur.com/ZrnGk.png) If you look at river mouths on Google maps you will find they are all like that. Your continent has glaciers too which might have left fjords in times past. Fjords! Have the ocean come in to meet your rivers and spread them out. Places like that are good sites for a city too - a nice river for water, access to the ocean for trade and listening to mermaids, but set back with some shelter from storms. [Answer] A few things that caught my eye: The Faich'iem desert is stuck between two mountain ranges that are snow covered, so they will produce melt water in spring, which will need to flow somewhere. So there should be a river flowing there somewhere. The whole scale of the map looks off if you want it to be a realistic continent on a twin earth planet. It looks similar to maps you'll often find accompanying fictional stories, but those are generally not too realistic either. Maybe you can include a scale to indicate how large you would like your continent to be? If I go by the density of forests and cities, this would not be a continent but rather an island, but that wouldn't realistically accommodate that many mountain ranges if those are supposed to be real mountains of several km high, and not more like hills. Also you wouldn't have a snow line on an island scale map, the area that is snow covered and frozen would change with the season, and you wouldn't find so many cities so near the edge of the permafrost. If you want this to be a real continent, several thousand km across, then the scales of the forests, cities and rivers are off. On a true continent scale you wouldn't see individual forests on a map because they would be just dark green spots, and they would be spread out everywhere. There would also be a lot more cities, assuming a medieval Europe population density. And there would be a lot more rivers large enough to navigate. The mountains still don't look very realistic on such a scale. In reality mountain/plain is usually not binary, often a mountain range is adjacent to hilly landscape, and once you get far away enough you will have plains. With this many mountain ranges relatively close together, the 'plains' in between wouldn't be very flat, but quite rough and hilly. Although that may be what you want. ]
[Question] [ In a post-industrial collapse scenario, what would be the most effective methods for contraception? Situation is a small scale civilisation with limited access to industrial materials and tooling but have solid understanding of science and anatomy. [Answer] Let's go through the state of the art contraceptives: * Condoms: to have latex you need access to tropical region where the suitable plant grows. Not an easy task for a post apocalyptic scenario. Same holds for polyurethane based condoms: getting the chemicals and the plants to run production is highly unlikely. Mind that in the past condoms were made using silk or animal guts, but they were obviously way less effective. * Pills: again, running a chemical plant is highly unlikely in a post apocalyptic scenario. * Diaphragms, spirals: getting the raw material and the processing plants is again the main issue. * Surgical: stitching to aseptic standards and lack of painkillers/narcotics can be the limiting issue, together with the non reversibility. * Natural method (abstinence during fertile days): this can be enforced by religious taboos, and it is probably going to be the most effective. Bottom line: in a post apocalyptic scenario what you lack in technology you can partially cover with numbers (if you have no Caterpillar to move a hill, you can have 100 humans do the job). why would you even aim for birth control? [Answer] **Prolonged lactation.** <http://www.webmd.com/parenting/baby/tc/breast-feeding-as-birth-control-topic-overview> The hormones which maintain breast milk production suppress ovulation; this is lactation induced amenorrhea. The article says don't count on it past 6 months but people routinely do, or try. It is not like a switch flips at 6 months and it stops working. An adjunct or extension of this would be maintaining the period of lactation by [shared nursing](https://en.wikipedia.org/wiki/Breastfeeding#Shared_breastfeeding). A woman can nurse other babies (or even animals!) after her own is weaned. It is not something given much thought in these days of baby formula but "wet nurses" were vital in the very recent past. If the mother died in childbirth, without a wet nurse you would lose the baby too. There are potentially big societal benefits to this practice especially in a resource poor society. One mother may not herself have the bodily nutritional resources to provide adequate milk, but one mother and several wet nurses would: the burden of feeding the child is spread over many individuals. Diarrhea (usually bacterial dysentery) from dirty water is a major cause of infant mortality even today; there are not bacterial pathogens in breast milk. Additionally there are (I think still theoretical) benefits of immunologically active molecules in breast milk - the pooled immune system of several nurses would be better than that of just the mother. Benefits of the prolonged lactation system for an author is that one need not get into issues like anal sex or mutual masturbation; I feel like that sort of pushes the fiction into a niche. Having all the ladies nursing all the time is different enough but not over the edge into freaky or prurient. [Answer] In a post-apocalyptic society, birth control will probably not be desired by most people, because you need a lot of young people for labor. But there might still be some groups who want it: Women who currently don't have a stable family situation, or who have a job where having a child would be very inconvenient; people who are very fertile and feel that they have enough children after a while, and a variety of other groups. Let's go through some options: **Hormonal methods** are probably impossible. Depending on how crafty your society is, they may be able to work something out by extracting hormone-like substances from plants and animals, but that may strike readers as unrealistic. **Surgical methods** — IUDs are probably not worth the infection risk, and female sterilisation is a major surgery that probably won't be available in your society. But *male sterilisation* in the form of vasectomies might be, because it's a relatively small and harmless procedure along the lines of pulling a tooth. This would almost certainly be irreversible, since it's barely considered reversible *with* modern medicine. **Barrier methods** have been used throughout history, and will probably continue to be used. There will be no rubber or polyurethane, so you'll be back to intestines and other natural materials. These work tolerably well, but don't seem to pose much of a barrier to viruses, so unlike modern condoms they won't protect against STDs. Spermicides might be used, there have been various recipes in history, but they might also cause irritation or infection, and will probably be less effective than modern versions, which already aren't that effective. **Natural family planning** (rhythm method) may play a role, but it requires a lot of discipline and measurements to be effective, in a post-apocalyptic society that may not be practical. If food is scarce, many women won't have a regular cycle, so the whole concept will be hard to apply. **Abortion and infanticide**: A lot of societies know about herbs that are likely to cause abortions. These are essentially poisons and much more dangerous for the woman than modern abortions. However, many societies have historically limited their number of children primarily by medical abortions. If they didn't know any reasonably safe abortifacients, societies often resorted to killing or exposing unwanted children after they were born. ## Conclusion So, my best guess is that young unmarried people would either use barrier methods or abstain from intercourse (sticking to other forms of sexual contact). Married people may use rhythm methods to space births, but won't be able to completely avoid pregnancies that way (nor will most of them want to). Older men who feel they have enough children in their family may choose a vasectomy. [Answer] There would be few options. Throughout history, animal intestines have been used as a barrier method. Pulling out is a viable, albeit not very secure, method. Cycle charting/ natural family planning could also work if a woman is regular, healthy, and ovulates normally (in the middle of a 28 day cycle). Natural family planning is fairly effective if all of these conditions are met (but far, far less effective than any hormonal method which would not be possible here). [Answer] The most effective method for contraception will be infant mortality. Mind you, there will be enough of it for fertility cults to occur. Avoiding pregnancy will be considered as throwing money out of window would, today. [Answer] **Copper IUDs.** Modern copper intrauterine devices are a mix of plastic and copper ([IUD on Wikipedia)](https://en.wikipedia.org/wiki/Intrauterine_device). However, if they have no access to plastics, your people could use just the copper. (Or silver or gold). People have been using IUDs for millennia (e.g. [history of IUD](http://www.alternet.org/personal-health/brief-history-iud-strange-ways-weve-tried-stop-pregnancy)). Since your people understand science, they'll know to sterilize the IUD properly before insertion, avoiding the risks of infection which the Romans and Ancient Greek women suffered from. [Answer] These are the historic methods of birth control I can remember: * Primitive IUDs: sponges and dried pieces of moss introduced in the vagina. Immediate cleanings with substances like vinegar after intercourse. * Condoms made of linen/wool: basically, like a thin sock around the penis. * Pull-out method. * Oral and anal sex, mutual masturbation. * Herbal potions, like ones with ruta (they were probably mild poisonings). However, I think in a collapse scenario they would use the same method as the Middle Ages: a bad diet and hard work made girls' menstruation happen later, less abundant and in an irregular form. And mothers breastfed the babies which acts as a natural contraceptive, too. [Answer] * **The most effective method would be to not have vaginal sex at all.** There are enough other forms of sex to keep people satisfied. And with people i mean men. Those who want to penetrate something. (i hope i don't sound childish, but for me as a man, that's how i feel.) * The next effective method would be a reusable-condom. something made of bicycle-tire-rubber or plastic bags which you will find anywhere. Or just those which are beeing sold. (something to look out for on your next raid...) * The next i would consider a copper coil (cooper IUD) which seems easy enough to manifacture, but like already stated in a comment, it needs training, know-how or trial-by-error. it all depends in what mood those post-apocalyptic citizens are and how much they lost already from the life before (see my personal note). *personal note:* * I wouldn't consider anal-sex a safe-form with the absence of antibiotica or other hygienic products (condoms, enema) to do it in a safe manner. * If i were to live in such a situation (ofc it depends if you're born into or know how life was before) i would probably resign pretty fast and just "pull-out" and don't give a damn. [Answer] * Primitive Female Condoms : blocking sperm from entering the cervix/uterus by inserting a foreign object into the vagina * Herbal and plant based contraceptives and abortifactents These have been used for thousands of years. For instance, wild carrot seeds are known to have effects similar to birth control pills. And black cohosh has abortifactent properties. * Natural spermicides such as copper or lemon juice * Withdrawal : self explanatory [Answer] **Leaving newborns to die in a place where they won't be found.** This was one of the "contraception" methods of choice after the fall of Rome, our world's one real-world post-apocalyptic scenario. Archeologists are still finding mounds of baby skeletons under old aqueducts to this day. [Answer] There is an early birth control method from Ancient Egypt using honey, acacia leaves, and lint [to create a cervical cap to prevent sperm from entering the womb](https://www.pandiahealth.com/resources/birth-control-throughout-history/). Some people in the post apocalypse could use lint/cloth, a sticky glue, and leaves to create a similar kind of birth control. It can be made more effective using acacia gum or some other substances that ferments into [lactic acid, which makes an effective spermicide](https://www.mentalfloss.com/article/83685/9-forms-birth-control-used-ancient-world). [Answer] I'm not sure I understand the point of this question. If there has been an apocalypse, why on Earth would you need contraception? Surely any apocalyptic event would wipe out most life on Earth (if not all)? So wouldn't the purpose of contraception be a moot one? In any case, assuming small pockets of humanity actually could survive the aftermath of an apocalypse (disease, famine, drought, plus many others depending on the cause), goal one would be to rebuild civilisation. That would mean children with as many varied females as possible to increase genetic diversity and avoid the complete annihilation of humanity... though in reality, we won't make it when it happens. ]
[Question] [ Just out of curiosity, could a large constrictor such as a python or a boa evolve to rely on camouflaging itself as a branch, with the right colouration and positioning, in the jungle canopy and ambush its prey (prey such as primates, rodents or birds etc). After all, we have discovered a genus of colubrid snakes, the vine snakes, which through natural selection have disguised themselves as vines to ambush unsuspecting prey. So could a constrictor, a python for example, evolve to mimic branches to catch prey, if so what traits could the snake need to blend in among the trees and how could such a large snake support its weight while hanging from the tree trunk? [Answer] You mean like a [Spear-Nosed snake](https://en.wikipedia.org/wiki/Langaha_madagascariensis)? Here's the only decent image I can find that shows it camouflaging itself as a branch: [![Spear nosed snake pretending to be a stick](https://i.stack.imgur.com/r7DdC.jpg)](https://i.stack.imgur.com/r7DdC.jpg) It wouldn't fool our human brains (which are [particularly good at spotting snakes](https://www.youtube.com/watch?v=AeOrYPvUsTE)), but it is good enough to fool its intended prey. [![Snake in branches](https://i.stack.imgur.com/bZcx2.jpg)](https://i.stack.imgur.com/bZcx2.jpg) [Answer] I don't see why not. There are already snakes that mimic branches. The [twig snake](https://upload.wikimedia.org/wikipedia/commons/a/aa/NHM_London_Twig_snake_%28Thelotornis_kirtlandii%29.jpg) is just one example. Pythons and boas are already ambush hunters. All you need is for a constrictor snake to look like a branch and you are good to go. Some arguments could be made that since such a snake doesn't exist that it could be sub-optimal for a large snake to look like a branch when a more splotchy pattern will do the job well enough. I wouldn't worry about it unless you're writing a bio paper. [Answer] Like a branch? Probably not. Constrictors are much too big and heavy to hold the appearance of a stiff object. The best you could make them do is appear as a growth on a branch, e.g. the [Tree Boa](https://en.wikipedia.org/wiki/Corallus_caninus) or [Tree Python](https://en.wikipedia.org/wiki/Green_tree_python). [Answer] A few different things are needed for camouflage: * Colour This is the first thing most people think of, but it's not much of an issue here. There are plenty of snakes with very effective mottled colours for camouflage. Bear in mind that it has to work for whatever prey your snake is targeting - so colours don't have to be that accurate for something like a rodent, but much more accurate for birds or humans. * Posture A large snake is unlikely to be able to support most of its body sticking out from a tree trunk. But it could lie flat against the trunk for most of its length, and then just have the head sticking out at an angle like a branch. * Shape A normal shaped snake would not be able to pull off the above posture, since the round cross-section will lead to strong shadows between the body and the trunk, making its presence obvious. The snake will need a solution something like the [mossy leaf-tailed gecko](https://en.wikipedia.org/wiki/Uroplatus_sikorae) - loose flaps of skin with rough edges on the sides of the body. Ideally, the snake should be able to flex its ribs to flatten its body, and in doing so extend these skin flaps to either side. That would allow it some very effective camouflage. * Movement Again, not really an issue. Movement will give away its position but all it needs to do is to move into position under the cover of darkness and then wait. Snakes are good at waiting. [Answer] If your world has a major boa eating predator species (like maybe giant eagles) then the disguise would not only enhance the snake's predatory capabilities, it would also provide a concealment defense. This would make the adaptation much more likely and thereby much more believable. ]
[Question] [ In the world as we know it, it seems like political power is almost always consolidated into a single axis (Lancasters vs Yorks, Republicans vs Democrats, Conservative vs Labour, etc). **This, in my opinion, is boring.** So how complicated could a legislature legitimately be? Obviously, there could not be a single party for every citizen or no one would be elected, but where could the line be drawn? Would (number chosen randomly) fifty different political parties all vying for control strain credulity for any reason? How long could that complicated legislature last before collapsing and tending toward two parties? [Answer] It can be pretty complicated actually. The United States only have 2 large parties and it's the same in many countries with a Westminster system. We tend to have a **first past the post** system where the winner is the one with the most votes, even if it's just 25% of the votes. The name come from the horses race where the leading horse wins no matter how far away the others are behind. This means that smaller parties have almost no chances to get elected in a single electoral district (or call it as you wish). In Canada, I think we have at least 11 parties in a particular district and most get almost no vote. That is why the legislatures are made mostly of two parties. On the other hand, countries like [Denmark](http://en.wikipedia.org/wiki/Danish_general_election,_2011), [Sweden](http://en.wikipedia.org/wiki/Swedish_general_election,_2010), [Israel](http://en.wikipedia.org/wiki/Israeli_legislative_election,_2013) and many others, have a lot of parties elected. This is because they use a **proportional system**. Basically, each party is attributed a percentage of seats equal the percentage of votes. Most countries requires the parties to have a minimum percentage of the national vote to enter parliament. I think it's 4% in Sweden. Otherwise the seats are redistributed to the remaining parties. **Does the Knesset have enough parties for you ?** in this system, the Green party could get elected with 4% of the votes = 4% of the seats. In a **first past the post** system, you usually need around 10% of the national vote to get at least 1 seat. It is possible to get elected with less support but it's really rare. The system really [distort](https://politics.stackexchange.com/a/5001/4551) the votes to the point it could be qualified as non democratic by some. **How does it work with so many parties?** They form coalitions. In order to share the executive powers of the legislature, the parties of the coalition accept to make concessions temporarily to work with the others in order to keep the coalition alive. They can go as far as giving important ministry to the smaller partners of the coalition. If it breaks, it's possible to form another one but if they can't, the parliament could be dissolved. It is possible to function without a coalition in a minority government but they usually don't last for very long. In Canada, the parties are required to vote on the annual budget. if the vote doesn't pass, it's election time. At any time, the parties can ask for a Vote of Confidence to take place. If the parliament doesn't have confidence in the executive (party with the most seats), it's election time. There is usually someone with the power to dissolve the parliament but it's a power that is rarely used. In Canada this power is in the hands of the Governor General and the Lieutenant governor in the provinces. **Now, trying to answer the question proper:** each party need to have something different from the others. They need to be able to make the population understand why they deserve to be in the parliament. With over 50 parties, the main problem is how they got elected in the first place. The state would need to cover a very larger area and population. They would obviously have general parties : right, centre, left, fascist and communist. But they would also have regional parties. From experience I can tell that regional parties are not really useful in a federal parliament but they are there anyway. In a galactic government, they might chose to divide the systems by regions or races to avoid mixing the local affairs with the more general matters of the galactic federation. It becomes impossible to have so many parties, so many people at the same place. This is another important concept of modern democracies: it's not a direct democracy like it used to be in Athens. One person is elected to represent thousand or millions of people. Having so many people only make sense in China but it's not a democracy. Not yet... [Answer] About how many axis, it is possible to have more than one. In Spain there is a left-right axis, but also a centralist-nationalist axis. In Belgium there is a Flemish-Wallon axis. In Quebec there is a canadien-independentist axis. In some other places there is a Christian-Muslim or Christian-Atheist axis. You can have a party in any of the places defined by a large number of axis. It just happens than some places are more comfortable than others (e.g. a christian-gay place will have few voters, while an atheist-gay and a christian-antigay parties will have much more, same for a communist-christian place or a rightwing-highsocialexpenses place). Also, there are plenty of different voting systems that allow for more or less variation. The first-past-the-post system in uninominal districts yield the lowest number of parties, while a pure proportional system in districts with high numbers of seats yields the largest. Now, an (imaginary) example. Let's set a country composed of provinces of different origin, much like Switzerland, with different religions too (let's say two) and half-integrated in a bigger entity like UK in the EU. We can have there the following parties in the country of Quux: Nation-wide: * Quux popular party * Quux democrat-christian party * Quux socialdemocrat party * Quux socialist party * Quux communist party * Quux green party Christian zone: * Quux christian-democratic party * Quux christian-socialist party (small) * Quux God's party (small) * Quux green party Foo provinces: * Fooist popular party (small) * Fooist democrat-christian party * Fooist socialdemocrat party * Fooist socialist party (small) * Fooist communist party (small) * Fooist green party (small) * Foo's Independence party Bar provinces: * Barist popular party (small) * Barist democrat-christian party * Barist socialdemocrat party * Barist socialist party (small) * Barist communist party (small) * Barist green party (small) * Bar's Independence party Muslim zone, Baz provinces: * Quux muslim-democratic party * Quux muslim-socialist party (small) * Quux sharia party (small) * Bazist popular party (small) * Bazist democrat-muslim party * Bazist socialdemocrat party * Bazist socialist party (small) * Bazist communist party (small) * Bazist green party (small) * Baz's Independence party [Answer] While direct representation would get you a lot of political "parties", you would probably want to focus on a legislature made of representatives of every area of life. If each major trade organisation, aristocratic family (see the House of Lords...), Learning stage (primaries, secondaries, college, university) has a single member, plus those directly elected, plus overseers like the Speaker and whips; you'd get a lot of complexity. Add one or more extra houses to oversee the legislative process, and it could be very, very complex indeed. You can make the legislature especially complex by having extra people whose job is to promote or enforce union between political parties in the event of a hung parliament and fill a coalition with independent ministers. Our laws in Britain are (roughly), put forth by ministers, worked and voted on by the House of Commons, undergo vetting and amendment by the House of Lords, voted and amended again by the Commons, all while party Whips tell ministers how the party would like them to vote, often in conflict with their coalition "partners". Once something goes through the Lords, it is made law. For the military our Queen can, in theory, have another look before she gives the nod, and veto any military action. A parliament can get even more complex, with double checks, extra houses (as mentioned), additional voting requirements, more elements vying for power, vetoes, decision deadlines (both the UK and the US have the concept of the filibuster) and the like. [Answer] Although parties denote groups of rough agreement, in practice they are not so monolithic. Very few votes go straight along party lines, and on different topics it's not terribly difficult to predict who will cross the aisle. Some of these factions are long-lasting enough to be given names: gang of 14, tea party, blue dogs, hawks, etc. Some fictional political systems that might encourage more parties: * A multi-state government, not divided geographically, but instead you are subject to the laws of only the party you individually vote for. * A division of powers based on topic. For example, separate legislatures for diplomacy, war, abortion, taxation, education, crime, immigration, etc. * A legislature where instead of winner takes all, any laws must be passed by a majority of each party. Obviously, these all would have their own problems, but they would make an interesting thought experiment. [Answer] Here is an extreme version of [Vincent's answer](https://worldbuilding.stackexchange.com/a/4029/8914). Bring in random ballot! Let's give your legislator a large number of seats, let's say 1000 (it being large is important). Now, everyone votes for who they want to be a legislator. Now 1000 random ballots are drawn, and those are the legislators for this term! This is, on average and [in the long run](https://en.wikipedia.org/wiki/Law_of_large_numbers), *perfectly proportional*. This means that basically every view point that's held by at least 1% of the population will likely be included. In the extreme, you can let people vote for anyone. This means you could have everyone vote for themselves, in which case, **everyone can have their own political party!** If you want to put some checks in place, you could do things like say you need 300 signatures to run (which exceeds [Dunbar's number](https://en.wikipedia.org/wiki/Dunbar%27s_number)), or make another legislature that is set up in a different way to that has some ability to limit the random legislature. Random ballot has the interesting property that it doesn't become denominated by career politicians (you can still be a successful career politician, its just that they won't have 100% of the power), theoretically. If 10% vote for a farmer, even though each individual farmer is not very likely to get in (since they focused on farming instead of politics), 10% of the legislature will be farmers. [Answer] As you think about options, keep in mind that the legislature's complexity will be deeply affected by the geographic(/-spatial?) dispersion and infrastructure of your society - especially communications infrastructure. If you mean to have elected legislators (which I read as an implication of your question), a highly literate populace with transparent access to information about the candidates and issues is more likely to support a complex multi-party system than a mostly non-literate populace, or a society with a censored or nonexistent press. Other possibilities: Maybe your legislators are hereditary positions, in which case family interests would play a greater consideration than the average citizen's. Maybe legislators are appointed by a central authority (humanoid, or a computer/divination tool), based on what will make the populace feel represented while not actually getting to choose for themselves. [Answer] In Ken MacLeod's novel *Dark Light*, each neighborhood **randomly** elects someone to a low-level council, which in turn **randomly** elects one of its members to a higher-level council ... I don't remember how many levels. A character says: > > Drawing lots is *fair*, even if it sometimes throws up a freak result. > With elections you're actually building the minority problem right in > at every level, and lots more with it – parties, money, fame, graft, > just for starters. What chance would that leave ordinary people, what > chance would we have of being heard or of making a difference? > Elections are completely undemocratic, they're downright > *anti*democratic. Everybody knows *that*! > > > [Answer] legislature can be as complex as the number of ballets a person needs to fill in. If there are more "houses to fill" number of parties would increase but not always. But the best answer is **Preferential voting system** if there are 3 parties that support important proposition A and one party that opposes it. Voters will release that in the "Winner takes all system" where votes are lost in the system it is illogical to have candidates for all three parties as that would play in the hands of opposing party. [More on this in by CGP Grey](https://www.youtube.com/watch?v=l8XOZJkozfI) ]
[Question] [ I am looking to have a Tunnel drilled through a world and deal with the physics of What happens in the centre of a planet, what happens with the heat at the core and whether it is faster to travel through a planet. However I'm interested in a reason for doing this? Obviously with any form of surface transport on any kind of reasonable sized world, it would be impractical to drill a hole through a planet to get to the other side, as surface transport would be easier. What kind of technological, environmental or chemical environment might force a society to decide to go through rather than around a planet? [Answer] **How they would work** The classic design for the tunnels would be a tube with a near-vacuum inside. Objects are dropped into the tube and they fall through to emerge at the other side. The tunnel itself would need to curve so the object can fall matching the spin of the planet as it does so. You would also need something (perhaps magnetic systems built into the tunnel walls) to keep the speed of the object up as even in a near-vacuum it would lose some speed, the same systems could be used to keep the object away from the walls of the tunnel though as otherwise drift could bring it into contact. The tunnel wouldn't need to go directly through the center of the planet and out at the same time, you can make the tunnel go to one side of the core and then bend around it to come out at any other point on the surface, like an orbit around the center of the planet although gravity gets weaker the deeper you go which makes the orbital math more interesting. For nearby destinations that would not be practicable but for anything a long way away it would be pretty fast and efficient once the tunnel is built. The main problems are heat and pressure, particularly as you approach the core. Keeping out the high pressure high temperature magma would be a massive engineering challenge. Vessels passing through would actually not be too badly effected though as vacuum is a good insulator. This would be made much easier in a smaller world without a molten core. **Why they would be built** The main advantages of going through the planet are speed and security. For example a planet under siege or in a state of cold war might make such tunnels in order to transport resources rapidly to wherever they are needed. The initial construction of the tunnels would be a huge effort but once they are built it would be very fast and efficient so ecologically sensitive civilizations may actually prefer it to air travel. A common concept with warp drives is that they only function in a low enough gravitational gradient. There is no science that I'm aware of backing up that theory but it's a common literary device. Drives working that way normally means the ships need to be a long way out in space to jump. The center of the planet though also has no gravity gradient so the hypothetical warp drives would function there. [Answer] I have to chime in here on a reason for the tunnel that no one has seemed to touch on. The most likely, and I think interesting reason to bore all the way through a planet is pure hubris. Why do we feel compelled to build the tallest building? Why do we care about record flights across bodies of water, or circumnavigating the world in a sail boat? The purest reason to make a tunnel through a planet is because you could. This reason might be seen as a sort of cop-out, but the reality is fairly well documented and even better known in a metaphorical context. The story of icarus, the tower of babel, etc. For world building this sort of idea could be really rich. Maybe an unknown ancient group made it, maybe it was made by "gods" or the like depending on your setting. I think everyone has covered the how, but narrative-wise remember that it doesn't necessarily have to be stable, or well-engineered. If done well your tunnel could be believable without anyone even understanding its background or history, or the physics of the thing. It could be an imposing, mysterious character on its own. [Answer] On a small enough planet, where such a tunnel is feasible, dropping an object through to the other side (or via many possible gravity-assisted routes) has [the same delivery time as a near-surface ballistic orbit](http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/earthole.html), with less work required to accelerate and decelerate because the planet's mass does that for you. The tunnel would be need to be held at a near vacuum for this to work effectively. If there was a constant requirement to deliver material one side to another, this *might* offset the rather large cost of building such a tunnel. [Answer] I'd like to propose a different cause for the tunnel. You mention being *forced* to go through it, but is there really a reason for them to be forced to make it before they're forced to use it? A tunnel to the core, reaching the other side can be dug out for mining (impractical but it might be hitting two birds with one stone), exploitation of heat for energy generation, technological and scientific experimentation, cheap housing and storage (energy generation and heating are close by, transporting good is cheap). It could also allow the easy manufacturing of various minerals and metals, by exploiting the extreme conditions through specialized scaffolding. Instead of creating artificial diamonds through explosions, you create pockets *within* the highly pressurized mantle and bake them there - just like how mom used to make them at home :P. Magma taps could provide exotic materials or allow using the magma to alloy with common materials for specialized uses. The lower gravity, combined with controlled near-vacuum conditions (for the constructed route, as the rest of the others have proposed), provide tremendous opportunities for construction, experimentation and energy saving. You can build a huge construct, like a spacecraft or space station, out of heavy materials that are close by, then break it up modularly and transport it easily to the surface, or launch it through rails on the side of the tube (considering the depth, there would be enough time to slowly build up speed to avoid the massive acceleration otherwise required to catapult spacecraft into orbit). And now, suppose everything goes wrong and the underground tunnel is mankind's only hope for survival. There it is, already furnished and ready for use, with housing available due to tourism and other market causes. Now they're forced to go underground and the tunnel is very efficient, necessary even - but they didn't build it out of necessity, which would make less sense no matter the overland threats and dangers. The planet is very, very, *very* deep - too deep to ever drill down that far just for cheap travel. [Answer] ``` Would there be any reason to bore a tunnel entirely through a world? ``` I can think of one reason and it's the same as why the chicken crossed the road - to get to the other side. ;) So, why then would someone want to use a hole instead of surface transport like you suggest? 1) It's cheaper 2) It's more reliable 3) It's more 'eco-friendly' 4) It's faster I could go on. Before going further we need to clarify some apparent assumptions. You seem to be comparing "*a world*" with *our* world. The primary reason I suggest this is because you suggest there is heat at the core - not all planets have hot cores. ``` ...surface transport would be easier. What kind of technological, environmental or chemical environment might force a society to decide to go through rather than around a planet? ``` What if "a world" had a mountain range around the equator which was too high to get over easily (even with an airplane)? What if "a world" was nothing but a mucky swamp, or a sandy desert, or an accordion of mountains that never ended? Again, assuming no airplanes. One does not need as much technology to dig a hole if a hot core is not an issue. And those are just a few geological hazards. We could also talk about wind patterns that made the equator a 'hot zone' from natural or man made radiation. What about a group of people, animals, insects, ... that make it nearly impossible (or at least extremely hard) to traverse from one side of the globe to the other. There are many scenarios one can imagine that makes it hard to get from one side of a world to another. Lastly, as other have noted, gravity is the main force providing the 'work' to get from one side of the planet to the other so once the hole was 'built' transportation costs could be minimal. If friction-less the object would emerge to the same height above the ground as it was dropped. Since a friction-less system of any kind is very difficult one could easily use electromagnets, tethers or other simple means to bring the payload whatever extra distance to the surface was required due to the losses from friction. [Answer] There are always reasons. * If a civilization how a highly effective creature to dig tunnels, but no good system of ground transportation, (No extra fast creatures or flying creatures) it could actually be an effective method of transportation. And a strong tunneling creature would make the cost reasonable. Of course, depending on the planets size, supporting the tunnel in the center may not be possible. * Another option similar to the one above would be if the above ground world was unsafe. If going above ground for even a short time was highly dangerous, people might have to go through the earth to easily travel. If it's safe to go through the center of the planet, they might try to do so. * The tunnel could be an elaborate secret passage. If someone country's worse enemy's capital was on the opposite side of the world, the best way to secretly get there would be to go through the world. Other paths would give the enemy too much time to prepare. * [Neil Slater's](https://worldbuilding.stackexchange.com/a/613/81) idea is also good. (Trying to be inclusive without copying) [Answer] Another reason to make such a tunnel: They are sending probes to nearby stars. The probes are boosted at extreme accelerations via a linear motor (or perhaps some technology we don't know) and a tunnel through the planet is the longest possible motor and thus the highest ejection velocity. [Answer] The tunnel could hold Ethernet cables to reduce latency for communication to the other side of the planet by pi/2. That assumes the light speed couldn't be worked around despite massively advenced technology. That shifts the problem to "why would low latency be so important"... EDIT: @ Toby's quip about High-Frequency Trading actually points to a semi-plausible scenario: a rich Corporation building it to gain an edge in stock trading. [See real-world analogy](http://www.bloomberg.com/news/2012-03-29/cable-across-atlantic-aims-to-save-traders-milliseconds.html) Or there could be a permanent, highly automated war in which faster coordination can yield a big advantage. Better yet: all inhabitants spend their days in Virtual Reality, some sort of MMORPG on steroids, and lags are inconvenient when interacting with someone half a world away. Resources are plentiful enough to make it worth it. [Answer] A good example of the above ground world being unsafe (as suggested by DonyorM) would be to place it very close to a star. Lethal surface temperatures combined with extreme radiation and no atmosphere would make it necessary to have *everything* underground, at which point radial tunnels look quite attractive. Another option would be a small planet with no atmosphere but a very high population, where the only remaining space for a new mass transit project is through the middle. There could be just a very high demand for sunlight and surface space (e.g. for farming) The key bit to managing the core temperatures and pressures is not really the size of the planet, but the density. It would also help if you were on a planet that rotated relatively slowly, since your radial transport vehicle will start the journey travelling at surface rotation speed and you will need a large part of your energy budget to slow that down as you descend and speed up on the other side (or risk hitting the wall of the tunnel). [Answer] Because, for whatever reason, this civilization is forbiden to reach orbit and going at the center is the only way to reach zero G Well... parabolic flight is another way to get zero G but come on.... let's make a tunnel ]
[Question] [ Imagine someone who could do everything [Lars Andersen](https://youtu.be/BEG-ly9tQGk) can, but with even more accuracy and power, in addition to being very strong and athletic and being able to do it with a heavier bow and faster arrows. Is it plausible that in the modern world, this person could, or rather would be utilized in military conflicts? This question - [How to explain the use of high-tech bows instead of guns](https://worldbuilding.stackexchange.com/questions/59497/how-to-explain-the-use-of-high-tech-bows-instead-of-guns) - is similar, but asks how to modify the world to suit the premise. In this question, I'm not looking to "explain" it by changing the world, but rather asking a - more or less - yes or no question. There are no archers on the battlefield today (as far as I know), but **if there was someone so skillful at archery, could he be of use in a modern military scenario?** [Answer] # Current archers in Modern Military ## Taiwan Believe it or not there is still one archery unit in a modern military: **Taiwan's (ROC) Mountain Company**. This unit uses bows in dense forest, heavy underbrush, mountainous terrain for its stealth (usually with ambush or hit & run tactics). ## China I don't know of any other unit which just uses a bow (as in long or recursive) but China does use crossbows for a number of operations (usually border & civilian suppression) as in: [![SF crossbow China](https://i.stack.imgur.com/HbRsE.jpg)](https://i.stack.imgur.com/HbRsE.jpg) Crossbow used for suppression [![Border Patrol Training](https://i.stack.imgur.com/Vf5uI.jpg)](https://i.stack.imgur.com/Vf5uI.jpg) Border Patrol training with crossbows (bolts are less likely to set of explosives when you hit someone) ## Vietnam Also, certainly within the modern time frame, the Vietnam war saw the Montagnards (native group working with the US military) using [crossbows](https://en.wikipedia.org/wiki/Crossbow#Southeast_Asia) against the Viet Cong. The Green Berets were rumored to have also found these effective for ambush and hit & runs and to have used them when working with this group. I have never found someone who collaborated this (one GB stated they were given one as a gift but said he never used it). Still, I have heard numerous stories of Montagnard usage at least. ## World War II Now WWII might or might not be modern, and this might not count but have to include it. There was this crazy guy named [Jack Churchill](https://worldbuilding.stackexchange.com/a/123254/54517) who actually fought with a longbow (& broadsword while playing bagpipes). This was not due to any tactical advantage - the bow broke before he could really use it - but was a moral booster. ## Other modern usage Military groups have really removed the crossbow & bow as assassination weapons (rifles are just better due to range) but they are still used in [jungle combat, with special forces, and as riot equipment](https://en.wikipedia.org/wiki/Crossbow#Modern_military_and_paramilitary_use). [![Peru Unit with crossbow](https://i.stack.imgur.com/w5EBp.jpg)](https://i.stack.imgur.com/w5EBp.jpg) Peruvian unit (note jungles behind them) in formation with crossbows **TLDR;** Any heavy camo area (jungle, forest, etc) where the silent aspect of the bow/crossbow is vital to the tactics small units use is the current usage in the military. [Answer] As far as I know, what Lars Andersen does, has more in common with stage performance then with bow shooting. In order to achieve such speeds, his bow has extremely low draw weight. I can't bring any scientific proof, but I think it's biomechanically impossible even for a fit human to achieve speed, accuracy and projectile velocity with a bow to be on par with contemporary firearms. There are additional problems with bow and arrow as compared to firearms in the modern battlefield conditions. The whole configuration itself is quite bulky - bows are pretty long (even the short ones), arrows are long too. It's much harder to shoot a bow from cover - you need to take a specific, comparatively exposed position and need space to spread your arms. Additionally, if we are speaking about battlefield usage, although arrows may have a chance against soft armor, they pose very little threat to trauma plates. So, the only scenario where bow and arrows can be useful is ambush (or assasination, as AlexP says), where your target isn't armored, doesn't expect an attack and you have at least one chance to loose a heavy broadhead arrow to disable him quickly. If your targed is armed or has bodyguards, the chance of follow-up shots are very low. If you have multiple opponents, you're better to have numerical advantage. [Answer] ## Yes Modern warfare is characterized by [asymmetrical warfare](https://en.wikipedia.org/wiki/Asymmetric_warfare), not so much by technology. Combatants in the middle east with little to no technology can evade America's drones, cameras, satellites, bombs, etc, by constructing and using caves and underground tunnels. One of the biggest challenges America faced in their war with Vietnam was not their technological or militaristic strength; it was the Vietnamese terrain, the local's knowledge of the area, and politics (the US could not bomb outside Vietnam, so the Viet Cong used the Ho Chi Minh trail which ran through Laos and Cambodia). The point is not whether or not he *could* be of use, but **in what situations would he** be of use? ### Black Ops and Assassinations Guns are loud. REALLY loud. Silencers don't do what Hollywood makes you think they do. There *are* small guns (sub-22 calibre) that can be made to be "silent", but they aren't lethal. This makes them rather impractical, because you (a) have to be close to the target and (b) would probably be better using a knife at that point so the target doesn't scream. If assassinating a high-profile enemy target, a really good archer could get "close enough" - being upwards of 50 or 100 yards away - and make a lethal shot with a silent arrow. Furthermore, because arrows don't rely on explosives, they'd be easier to deconstruct and take through airports, across countries, hide in cars, evade detection by police dogs (who are trained to sniff-out explosives). Any type of assassination or black-ops situation could make use of such a skilled archer for the simple advantage of *sound* - he can move quickly, strike targets, and not reveal his location. Even simple issues like navigating through a forest would allow him to kill and eat his own food without risking the gunshot being heard miles away. This makes him a silent predator that can quickly enter (and leave) difficult terrain silently. Or, rather, he can *camp out* in difficult terrain silently. ### Civil Unrest Suburban warfare is hell for everyone - if a governing party doesn't (or can't) blow up a city, and that city is extremely hostile, every single building because a potential hiding spot, explosive, etc. Without the "boom" of guns, an archer on a rooftop can hit a target without making it obvious which building he is on. He can even release the arrow and run away before the arrow makes the impact. Not relying on gunpowder makes him especially dangerous, as he can either recover or manufacture his own arrows with relative ease. [Answer] There are a few answers discussing the relative merits of rifles and bows, and we all know that rifles are going to be the better general-purpose tool. That's not really news. That's probably not what you're after, though. The basic principle of armed conflict hasn't changed since the bronze age: stick them with the pointy end. Arrows do that just fine. The question then becomes, *why* can't I put a cool guy in a story with a compound bow and a thick quiver? # Targets ### Infantry Plastic-based and ceramic-based armor is basically impervious to arrow strikes. A cutting projectile would be better than a low caliber handgun against polymer fabric armors, but a rifle will cut right through those anyway too. This limits your choice of targets to people who aren't geared up for a serious fight: night raids, supply stations, police, some limited ambush situations, etc. ### Light vehicles You can get through windshields and door panels and hit a target on the other side with an arrow at reasonably close range, but not reliably. If your arrow glances off, it's not subtle. See <https://www.youtube.com/watch?v=yAcWu6Y68pA> for a demonstration. "Reasonably close range" isn't a good plan, though. More on that later. ### Armored vehicles Forget it. Then again, the rifleman can't shoot through these either. That's the point. # Battlefields ### Close range If you're fighting one person with a gun, the element of surprise is pretty much all you need. Drop your target, get into cover. If there are four or more people with guns, you're going to die. They have better maneuverability. An archer needs to make larger movements to get out from behind cover in an extended firefight than someone with a gun. ### Long range This is a little more interesting. Arrows maintain lethal force through a parabolic arc better than a bullet, which makes the effective range of an 80 lb. compound bow very comparable to a general purpose rifle like the M16. Not *longer*, mind you. Comparable. They both come in at about 500 yards. A heroic figure might be a better marksman at that range than red shirts with firearms, even though in the real world, the arrow is more sensitive to environmental factors like wind. Creative license! ### Urban There's almost no such thing as an extended sight line in an urban environment. You could lob arrows at groups from a safe distance, maybe try to force workers indoors, but otherwise, you're limited to the short range constraints above. Also, trying to shoot out of a window will limit your fire lines and, in turn, reduce your maximum range. ### Forest This might give you better angles for hitting light vehicles at short range. Other than that, this is just a trap. What interesting targets are going to be on foot, alone, and lightly armored? ### Open I wouldn't pick a fight on the open plains. You'll just get shot. There are some interesting tactical opportunities for beaches, though. You can fire from a boat into open windows or at off-duty combatants. You can catch sailors boarding, supplies leaving harbor, things like that. Basically, it provides an exception to the short range limitation of the urban environment. # Summary The person you're describing here isn't really a soldier anymore. He can hit civilians, unaware combatants, and their support troops. He can't take and hold territory. All he really can do is cause disorder and break morale. This person is a terrorist. ]
[Question] [ > > Report! Correct aim 2-20 fore, figure in enemy speed at negative 15 knots relative decelerating. Ready? Fire in Sequence on my mark... MARK! > > > LCDR Arnold Dering, Commander of the "X"-Turret, GKS-B-RW41 "Adamanta" --- **NOTICE**: I am looking for a solution within the confines given in the question. If your answer does not work without introducing anything to the world (e.g. super precise lenses, magical hotstones, etc.) please take the time to *weigh up the pros & cons* of whatever you introduce. --- In my [mind-bogglingly breathtaking conworld](https://worldbuilding.stackexchange.com/questions/19788/how-would-flora-behave-on-a-two-continent-planet) *heavily armoured airships majestically float through the skies* with help of [a science-defying, yet well thought-through lighter-than-anything material](https://worldbuilding.stackexchange.com/questions/19630/is-this-concept-for-an-lta-gas-associated-element-lifecycle-feasible)1. Above the skies they duke it out between each other armed with machine guns, flak, artillery. Machine gun & flak fire saturating patterns & methods against flying enemies are well enough explored and used in our world. What **I would like** though, is **to have the larger airships** not only use their artillery to reduce bunkers and buildings to rubble, but **fire shells at each other** - in the air! The only issue *I* see is a way to properly report misses in order to adjust aim for the next salvo. If they miss, the shell will simply hit something on the ground - potentially miles away from the target. To solve this I was thinking about introducing a *marker shell* being fired until a promising bearing is achieved. This marker shell could either be something along the lines of traditional tracer bullets, or a self-detonating shell being primed to explode after a certain time (distance / speed). In my understanding this would provide the spotter/targeter/aimer with a reference point - quite similar to the *splash* used by World-War navy gunners - being close enough to the target to be actually useful. 1[Here's a question about how to control altitude](https://worldbuilding.stackexchange.com/questions/41582/what-ways-are-there-to-keep-a-steady-altitude-with-large-fluctuations-regarding) with this physics-defying figment of my imagination. --- **Q**: Are there any issues with the described technique(s)? A good answer should address the following topics: * What is the advantage/disadvantage of *tracer shells* over the *detonating shells*? * What is the advantage/disadvantage of *detonating shells* over the *tracer shells*? * If none of the techniques can work, why - what fact about aerial combat did I miss out on? In *addition* it would be amazing if answers that explain *why this does not work*, to include a section proposing alternative solutions come close/to a similar result as what I am describing in the above prose. --- *Technology*: The world is set technologically somewhere between the industrial revolution and the invention of internal-combustion-engines. There's been heavy development and optimizations regarding steam-driven-engines as there is, at least in parts of the world, [little to no oil available](https://worldbuilding.stackexchange.com/questions/57761/how-to-make-the-development-and-use-of-steam-engines-preferred-over-that-of-comb). Electricity is something fairly new and so far doesn't go further than being used for creating light aboard airships and being used for telegraphing (little to no electric infrastructure). While oil is found and burned in other parts of the world, in this part of it the most commonly used fuels burned for heat are coal and peat. Additionally natural-gas, coal-water-slurry and fishoil are most commonly burned in lanterns to provide light. --- *Speeds*: These Airships, most of the time, consist of two or more parallelly arranged lifting bodies with most of the mass of the ship hung between them, the center of mass being below the lifting bodies. This arrangement is intended to give them a sort of stability in the air similarly to a [catamaran](https://en.wikipedia.org/wiki/Catamaran). While some airships have multiple dedicated steam-engines, most of them feature central engine-rooms where work-power is diverted to engines, winches, etc. using gear-assemblies, drive-belts, drive-shafts, air compressors, ... Under normal weather conditions military airships rate average speeds between 60-90kph. Military ships feature multiple, often pivotable, engine-pods along their hulls, allowing the application of thrust in almost any direction; the bigger the ship, the more pods naturally. In general speeds, etc. are based on WW1 & Interwar-Period craft, such as the [Schütte-Lanz Airships](https://en.wikipedia.org/wiki/List_of_Sch%C3%BCtte-Lanz_airships). --- *Tactics*: There are different classes of ships that refer to different sizes, armaments and tasks of the ship, the largest of these reaching widths of up to 160m and lengths of up to 400m. Aspect ratios vary from smaller ships @7:2 to larger ships @5:3. Armament and engagement-tactics are loosely based on WW1/WW2 naval combat. That is cruisers/battleships would primarily fire heavy shells over vast distances (mostly for land bombardment), while smaller/medium ships would feature lighter weaponry to engage in ship-to-ship fighting (e.g. destroyers). In addition almost any ship down to [corvette-size](https://en.wikipedia.org/wiki/Corvette) carries a compliment of spotter/fighter/bomber biplanes. While a corvette would carry at most 1-2 planes, a destroyer would already carry a wing of 3-6 planes, a battleship half a squadron (~a dozen planes), up to carriers hauling multiple scores of plane (being basically huge flightdecks with underslung multi-story hangars). [Answer] **What you are describing is more like the art of Rangefinding** This was a major research area in both World Wars. The main issue was battleships from WW1 onwards, because of the large ranges involved, had enormous difficulty judging distance. It was generally regarded that the British had the best [Rangefinding](https://en.wikipedia.org/wiki/Ship_gun_fire-control_system) techniques, but even so only 3% of fired shells actually hit their intended target. As targets are far away from each other, there is no advantage to 'smoker' shells. Keep in mind at a distance of 30km or more, it takes a long time for a shell to ballistically reach its target, even several minutes. In this time the ship could move, wind factors could alter, and the tactical situation may change. Your 'marker' shells would be more the go to detect if there was a hit, although close observation from spotter towers may give you this data anyway. In early (prior to WW1) battles Russian battleships were not successful against newer Japanese battleships. This was in part due to the technique of the Japanese firing a large salvo with each shell of a different range. This 'shotgun' technique allowed them to find the right range quicker, whereas the Russian ships would still firing one at a time. Other nations quickly adopted this, but with the advent of range finding computers, devices mounted on spotting towers (hence the many platforms in a typical Battleship) accuracy became greater from the first salvo anyway. Later, [radar was the preferred method](https://en.wikipedia.org/wiki/Fire-control_radar) of range finding, [combined with computers](https://en.wikipedia.org/wiki/Fire-control_system) to increase accuracy. Artillery nowadays can be very accurate on the first firing. In your world, airships however move in 3-dimensions. I would expect the following then: * Spotter towers on your airship, with platforms extended as far 'wide' as possible, to try to increase the accuracy of your range finding system. Rangefinding devices mounted to the platforms, and data fed to a central command deck with tables/calculators to determine range. * Shells to be fired more often and in multiple salvos. Unlike battleships though, your target could be a different altitude in addition to direction, so your shotgun approach would be to fire multiple shells in a grid / hexagonal fashion to maximise chances of a hit. All shells should be effective to give you the most advantage in the shortest time frame. * There is a great advantage to height. The higher you are, the greater your effective range of shells. Therefore I would expect your airships as soon as detected would both try to rise as high as possible. Unlike battleships, as an airship captain lifting your airship is as good as a higher range gun, so airships over the top of you have a distinct advantage. I would imagine 'emergency blow orders' would be the first command that would be given. * However at the end of the day, it may well be that your battleship airships give way to being carriers. This is because instead of range being measured in the tens of kilometres, with smaller, lighter, faster craft (such as mini-airships, gliders or planes) force can be projected over hundreds of kilometres - each with its own armament. This means a smaller faster craft can come in to close range, or at 'high altitude' and be equally if not more effective than a large heavy vessel. This happened in real-life, leading to the demise of the grand Battleship, which simply became bombing targets for more agile lighter craft. [Answer] **Which you use depends on what you're firing.** If you're firing a machinegun (a "hose") then tracers just make sense: you can see where the line of what you're firing connects with what you're shooting at, how much you have to lead, how much up you have to fire, etc. If you're firing a volley of single-shot things, then having them explode colorfully on fuzes at roughly the right distance gives you some great advantages: stuff that "misses" has a second chance to do damage from shrapnel; and you can see the pattern it paints around the target. **Tracers and rainbow-shells both help your foe locate you and return fire.** [Edit: it has been pointed out to me that there are tracers which only shine backwards towards the firer... which seems like it would *reduce* the problem, but not *eliminate* it unless every round hits, since they'd see the ones that missed and went past. If every round hits, you don't need tracer rounds anyway.] Say you always fire a rainbow of shells. The foe, on observing a red explosion to their port and an orange explosion closer but still to the port, will know that you are astern of them. Even if you don't fire in color, a foe seeing an explosion to port and then a later one to the starboard will know you are to port. You could stagger your volley deliberately, to make them think you're in a different direction, but that would also reduce the accuracy of your information from the volley. Regardless, the shotgun volley lets you tell where in that volley the foe was, and to focus your fire around that. But once you've found the right place to shoot at by the outcome of your volley, you want a way to continue range-finding as each ship maneuvers around each other. You need a computer, but you don't have even the most basic electronics. If we are to go by history, you have two options: gears/cams, and pigeons. **Cams and gears are pretty freaking incredible.** Back in WWII, we couldn't carry computers around in planes. Computers were the size of buildings, and needed a fleet of engineers just to keep them running and to fix all the bugs. Instead they used mechanical systems. The resource you want to read on this -- and I suspect that, given the work you've put into building your world already, you actually will read this, once you get how important it is to your setting -- is **Ordnance Pamphlet 1140: Basic Fire Control Systems**, Section 2, which you can find at: **<https://maritime.org/doc/op1140/>** Think the differential gear in your car was just a thing that let the wheels rotate at different speeds? No, it's a computing system that does addition and subtraction! And similar things let you multiply, divide, differentiate, calculate trig functions, and more! This is something that steampunk worldbuilders typically don't get. Cams and cogs aren't decoration, any more than chips are decoration for chip-punk. They are essential parts of *mechanisms*. Inputs and outputs are hand-cranks, levers, switches, and probably even a targeting reticule that drives two axes which are integrated together. Line it up with the target to get X and Y, slide the range slider, merge with inputs from the wind-speed and direction sensors, the gyroscopes to predict rotational velocity in pitch, roll, and yaw, and then the *velocity* with which your targeting reticule moves as you track the foe in order to calculate their relative velocity and get a "lock"... **Which is where pigeons come in.** Because, sure, you've fired the thing in basically the right direction, but if your shell has vanes on the tail, it can direct its flight to actually hit the thing you fired it at. But fitting even a mechanical computer into a shell, particularly one which could recognize a ship from any possible angle and target towards it... not possible. But you know what can do all that, and is light and portable? Pigeons. So [Project Pigeon](https://en.wikipedia.org/wiki/Project_Pigeon) was born: > > One to three pigeons, trained by operant conditioning to recognize the target, were stationed in front of the screen; when they saw the target, they would peck at the screen with their beaks. As long as the target remained in the center of the screen, the screen would not move, but if the bomb began to go off track, the image would move towards the edge of the screen. The pigeons would follow the image, pecking at it, which would move the screen on its pivots. > > > From: <http://www.historynet.com/top-secret-wwii-bat-and-bird-bomber-program.htm> > > the pigeons learned to rap out as many as four pecks a second for more than two minutes without a break, and would work feverishly to prevent the target image from moving off dead center. > > > [...] The pigeon had to peck correctly or he got no food at all. According to the report on these experiments: ‘There wasn’t a single washout in the entire class of 64. Every bird earned his wings with an A grade.’ > > > [...] Target pistols were fired only a few inches from a bird’s head. The pigeons didn’t miss a peck, didn’t even look up. Other extremely loud noises were introduced. Again, the pigeons stayed at their task. Skinner also put the pigeons in a pressure chamber, setting the altitude at 10,000 feet. They were also whirled around in a centrifuge, put on pure oxygen and exposed to bright flashes, simulating shell bursts. High vibrations were also introduced, and the birds were subjected to massive G forces without harmful effects. > > > [While] pigeons were never used to bomb enemy targets, the test results show that they could have. > > > If electronics had not come along, organic control would likely have become the main way of making guided missiles. **TL;DR: As well as tracers (for guns) and fuzed detonation (for cannon), you may also want to look into cams, gears, and pigeons.** [Answer] Tracers are nice for a visual image of your projectile but they rely on light, and are obviously more visible at night; fighting above the clouds in bright sunlight might also hinder this. In order to keep effective artillery shells, I would reccommend using smoke trails as a form of tracer. Similar to the colored smoke you see stunt planes release at air shows. I believe this would solve the visual element of what a tracer would provide; and as an added bonus the lingering smoke would provide an idea about air currents relative to the target as well. [Answer] You have two major options aside from tracers/smoke-trails. One is to build a human intuition for it. Leading an aircraft in flight in order to shoot it down is a skill that is ecan be obtained with sufficient practice. I imagine that if you practice with tracer/smoke rounds (to speed developing the intuition), you could then take your trained gunnery-officer onto a real battle field and he could do a fairly good job at getting near the enemy without tracers at all. The difference between having the tracers for training and not having them in battle could make for some interesting challenges for young gunnery-officers The other option is to build a mechanical computation device to help you out. I imagine the use of one would go something like: 1. Estimate the distance to the target 2. Line up eyepiece number 1 with the craft 3. Wait five seconds 4. Line up eyepiece number 2 with the craft 5. Enter the elevation and azimuth of both eyepieces into a table, look up the distance, and read off the required azimuth/elevation for your guns. 6. The table would be valid for a fixed point in time from the readings, so communicate these to your crew and fire your guns. Building such a device would not be hard, so long as trigonometry and parabolas are known mathematics (as they have been for hundreds of years now). One cool thing is that it uses the relative velocity between the craft - so it doesn't matter if both vehicles are moving, rotating or whatever, it will all get factored in with the same basic math. Similarly, so long as the relative timings between aim1-aim2 and aim2-shoot are consistent, the exact timing wouldn't be too important (though faster would be more better). Tables may not be efficient with six entry points, so perhaps you could wire the eyepieces into a mechanical calculator of sorts. I can forsee some fun-shaped cams containing the balistics information. I can imagine you could build such a system directly into a gun-turret. You have one dial for the distance estimate, and then you line up the one marker, wait five seconds, line up the next marker, and some mechanics places a third marker where to shoot. If you have two-man gunner teams, and some way to get a round into a moving breech, one man could reload while the other aims. Aim, aim, shoot. Aim, aim, shoot. Depending on the size of your vessels and the distances you are working at, and the accuracy of your measuring devices (stereo offset from the bow/stern of your craft) or your intel about the size of the enemies craft (measuring by relative angle from front to rear of there craft via lenses), you could potentially have a person who's duty it is to measure the distance to the enemy and inform all the crew members. Whether the information could reach the gunners in time for it to be useful is another question. So what is the feasibility of building this mechanical aiming device? Yes it is possible. People built mechanical "[differential analysers](https://en.wikipedia.org/wiki/Differential_analyser)" and extremely complex mechanical computers during WW2. [Here's one for calculating a ship's position](http://worldwar2headquarters.com/HTML/museums/USShornet/computer.html), and really, this whole concept is just an extension of devices such as the [Kerrison Predictor](https://en.wikipedia.org/wiki/Kerrison_Predictor) - during the wars, they had to try aim ground-based guns at high-flying bombers, which is virtually the same problem. Quote from wikipedia: > > The [Kerrison] Predictor solved the problem by doing all of the calculations mechanically through a complex system of gears. Inputs to its calculations included wind speed, gravity, ballistics of the gun and the rounds it fired, angle to the target in azimuth and altitude, and a user-input estimated target speed. Some of these inputs were fed in by dials, which turned gearing inside the Predictor to calculate the range (from the change in angle and estimated speed) and direction of motion. > > > Here's a fun idea: lighter-than-air torpedos. I suppose they're actually called rockets, but if you can make them neutral buoyancy due to your handwavium, you could fit them with gyroscopic stabilisers [[complete service manual]](https://maritime.org/doc/torpgyro/index.htm), and point them on their way. [Answer] # How to blast an airship ### You must fire tracer rounds In order to find range, an airship opens fire with tracer shells until a suitable range is detected. Tracer shells will burn brightly when fired. Each gunnery team has a crewmember whose job is the spotter. Their important job is to track **the time it takes for the shell to cross the plane between the firing and target airship**. Whether the shell passes in front of, or behind the target, that time is all that is needed. A tracer round must be used; smoke or detonation is not an acceptable alternative. In WWI style naval gun battles, all ships in an inferior firing position will be actively emitting as much smoke as possible to obscure their own positions. A assume your airship battles will be the same. The only reason not to deploy smoke is if you are entering battle with overwhelming force. Smoke will make targeting very hard in the absence of any radar. For this reason, very bright tracers are crucial to being able to tell where your shots are landing. ### Rangefinding with tracers The time that the shell spends in the air, along with the angle of fire of the gun, along with the known muzzle velocity of the gun (assuming the cartridges are produced with such quality that the muzzle velocity is well known), are all you need to know to calculate the range of the tracer. The angle of fire of the gun must be known with respect to an *absolute* level. The airship will presumably have some roll (and possibly pitch and yaw, too) that will affect the firing of the guns. The absolute angle of the gun relative to the ground is what you need to know. Let $\beta$ be the angle of the gun as fired, $v\_c$ be the known muzzle velocity, and $t$ be the time in the air. Now let $\alpha$ be the angle between the firing vessel and the target vessel, and $d$ will be the distance we calculate. It will look like this: [![enter image description here](https://i.stack.imgur.com/dNy3U.gif)](https://i.stack.imgur.com/dNy3U.gif) First off, you can calculate the horizontal distance that the projectile traveled before it passed the target, simply, using \begin{equation} d = v\_ct\cos{\beta} \tag{1}\end{equation} If he tracer passed in front of the target, then this distance is short; if it passed behind the target, then this distance is long. Adjust accordingly. However, there is additional value in calculating the angle of engagement between you and the target. The equation for the height above reference of a projectile, a one dimensional distance, based on the initial elevation above reference, and the initial velocity (in the one, vertical, dimension only), is \begin{equation} d = \frac{gt - v\_c\cos{\beta}}{\tan{\alpha}} \tag{2}\end{equation} ### What did all this math get you? You can now create a lookup table with the solution to these equations. Given $t$ and $\beta$ you can find out how far your shell traveled, and thus, how far away your target is. Each table of lookups will be for a certain cartridge or powder size (however your guns work), such that $v$ is constant for one table. Equation (1) gives you a simple estimate of the distance at which your shot passed either in front of or behind your target. Equation (2) gives a further way to you a way to estimate what angle you should make your first few shots before you range in. This second equation also lets you cover expected changes in relative elevation, such as if your are climbing or descending relative to your target. You can measure $\alpha$ with a sextant or a similar piece of equipment. The lookup table will be used the same way, except it will be a three way lookup table with $\alpha$ included. ### How do you range in on the target? Alright, let us imagine that the airship has its guns mounted in a limited set of turrets, the way that an *Iowa*-class battleship has its nine guns arranged in three turrets. Each turret is going to fire tracer rounds at first, to get a range in on the target. As it is firing, the gunnery officer for that turret will note the times to target, elevation of the gun that fired the shot, type of cartridge involved, and approximate angle to the target. Using all this information and the lookup tables, for each shot you can develop two separate estimates of distance to target. You write these distances on a board in front of you in chalk or grease pencil or something appropriate, in two colors, noting near and far. With use of the targeting board, you will quickly be able to use the multiple guns of the turret to range in on the target. Once you are close, you switch to firing real, explosive rounds, with perhaps every fifth shot being a tracer to ensure you are on target. With all the smoke, and explosions and other ships firing on your target, this won't be easy. But with gun crew training, a competent crew should be able to keep on target during a pitched battle in the skies. [Answer] Problems with exploding marker shells: * You need a flight time estimate to make the shell detonate at the right point. Where does it come from? If you have distance and speed with sufficient precision to set the fuse, why do you need ranging shots? * You might or might not have reliable time fuses. Also, they would have to be set before the shell is loaded, which could be a lengthy process for a big gun. Advantages of exploding marker shells: * You can make them explode in separate colors for separate turrets, so each turret can tell theirs from the others. Problems of tracer shells: * They work best for a relatively flat trajectory. On a ballistic arc the tracer might no longer point towards the observer. * They affect the ballistics. The destructive shells might have a different trajectory. Advantages of tracer shells: * Simply make all of your shells tracers, that way the first shell to hit already does damage. With an airship, even an armored one, that first hit could be decisive. General problem: Your airships maneuver in three dimensions, and they will probably be faster than watercraft. That could make any long-range, indirect fire artillery questionable. The best WWII fighter pilots had the nerve to close in with the enemy and to fire a devastating burst. Hitting at more than a few hundred yards was almost impossible. Even if you extend the ranges to a mile or two, the big guns would have to be fired in a very flat trajectory to hit. [Answer] How advanced are your computers? Firing guns against targets at different altitudes is a lot trickier than just trying to hit something at the same level. The US artillery had a real problem fighting in Italy, as the range tables weren't very useful when the artillery and target were at different heights. Correcting fire is not going to work well, as the airships are apparently reasonably fast and can move in three dimensions. The shells will have to be tracked, and a straddle would be some going over the target and some going under. Tracer rounds will not be all that useful if they have different ballistics than the real ammo. If you can put some sort of tracer in the base of the shells, you can more easily tell if you've got a straddle. (Look, you've got lieutenant commanders commanding individual turrets. Those have to be some pretty big shells.) One way to fight is to get sufficiently close that trajectories will be pretty much flat. At that point, we're looking at something pre-WWI, with individual turrets firing at will without any sort of central fire control. At that range, you can probably keep track of those huge shells with binoculars. It also keeps battles more compact, which is better if you're doing them visually. In WWII, for large ships, two miles was ridiculously close range. I know of one photograph from WWII with ships from both sides on it, and you can hardly see the Japanese. [Answer] Since you are already bending the rules a bit, perhaps use a smoke tracer round? A smoke trail naturally blows away in the wind, but thats not what you'll be using it for. Like fireworks the smoke would have a color that changes over time. This allows the artillery battery to gauge the time it took before the shell flew by the enemy. An additional advantage is that the smoke left behind will blow passed the enemy and give a reference point to judge how close it went passed, combined with the color of the smoke trail you have a good idea of your shot, for a relative amount of "good" when talking about two fast moving ships in 3 dimensions in different light&weather conditions that judge distance based on something that literally moves with the wind. [Answer] **Special forces aerial attack** I agree almost entirely with the answer by flox. For that reason I won't repeat the arguments. I'll offer a different solution and that is human attack missions. I'm not talking about the Japanese Kamikaze pilots. That is a possibility but it's expensive in destroyed equipment and lost human life and also involves turning the large craft into an aircraft carrier. Instead I propose gaining height on your opponent and launching one of your crack team of wing-suit flyers. The flyer carries a magnetic mine and when within suitable proximity, pulls the pin and lobs it at the enemy. Then they peel off and head towards a land base where they can prepare for their next mission. The following video shows just how precisely these wingsuits can be piloted. **Video of Wingsuit Flight Through 2 Meter Opening - Uli Emanuele** <https://youtu.be/-C_jPcUkVrM?t=84> I'll see what I can come up with for velocity and glide slope. I'll just say that they are such small, fast targets that they will be very hard to shoot down. [Answer] **Wire-guided missile** The problems and explanations have been thoroughly explored as I type this. I won't repeat them. I'll offer a different solution. > > Electrical wire guidance dates back to the 19th century > <https://en.wikipedia.org/wiki/Wire-guided_missile> > > > A direct hit is not necessary. Aim high and the missile will fly over the enemy craft. Course adjustment happens *in flight*. It doesn't have to be electrical. The missile then falls and can be reeled in until a magnetic switch detects the enemy's hull at which time it explodes on the far side of the craft. **Passive missile with cable** As above but doesn't doesn't allow for course correction. [Answer] ## Use Math *...So, I know this is an old question, and you may not care anymore, but it caught my eye in the related questions panel of something else about airships.* Flox was right that this is a matter of rangefinding, but forgets the best possible method for it: Triangulation. This does not require fancy electronics. For this to work all you need is 2 spotters. I would suggest 1 at the bow and 1 at the stern sitting in predetermined places. Each spotter has a crosshair attached to a 2-dimensional swivel where each swivel is marked by a vertical & horizontal compass. Such technology was already common in the form of sextants. When each spotter puts the target in his crosshairs he calls out the vertical and horizontal angles. Both spotters should have the same approximate vertical angle, meaning that your actual relevant data set is θY, θX1, and θX2. Well trained spotters will be able to not just aim at the target, but lead it appropriately as there will be a delay of several seconds between marking the shot and everything that goes into landing a hit. Then you will have a 3rd person using look-up tables to make good use of the spotter's info. Let's call him the gunnery commander. He can use the numerical values to find an approximate firing solution. The lookup tables were of course compiled through months of meticulous calculations and testing prior to the battle and is specific the the distance between your spotters and the guns in question. But once the gunnery commander has looked it up, he then calls the angle and elevation the gunners need to fire at. With everything pre-calculated and the gunnery commander well trained, this should only take a couple of seconds at most. Once the firing solution is called out, all of your gunnery operators will swivel their cannons to the angle and elevation called out and fire. All of the shots should come pretty close to the target, but slight deviations of human error between gunners will make sure that not every shot hits the exact same spot; so, the shots will saturate the general area that the enemy ship is precalculated to be without having to fire a single tracer shot at all. **EXAMPLE:** **Spotter 1:** -17 mark 126.3 **Spotter 2:** 125.8 The gunnery commander standing next to a giant rolodex of charts upon hearing -17 flips his carts to those where the enemy elevation is determined to be -17 degrees. He then finds the row for 126.3 and then tracks to the column for 125.8. He then calls out the contents of the cell **Gunnery Commander:** -14.3 mark 126.05! ...and everyone swivels their cannons to fire at that angle. The reason this works is because it follows the law of sines which states that you can resolve all 3 angles and sides of a triangle knowing only 2 angles and 1 side. The known side here is the distance between the spotters and the 2 angles are θX1 and θX2. So, the average of these two angles gives you the angle to fire at, and the distance is determined by the average of the two remaining sides of the triangle that a mathematician calculated for your in advance. Also, the angle you need to fire at is determined by the velocity of your cannon which you should already know. The distance to target which you just determined, and the elevation to the target which is determined by θY. This means that your mathematician can skip showing his work and jump straight to telling your what elevation you need your cannon to fire at to intersect the target at that range. All of the math required to do this within a fair degree of precision existed by the late 1700s; so, it should work within your setting. [Answer] "Marker shells" only work for consistent fire from a stable platform because only in a fixed position is your next shot sufficiently similar to make it worthwhile. So-called 'walking your shots' was firing from a comparatively more stable platform than airships, but even then they threw out a lot of ordinance for each actual hit. Artillery between airships renders the guess-and-test shooting functionally useless due to too much movement through the air and including the added difficulty of changing relative heights. The force of firing a shell (remember your Newtonian mechanics) is significant and will move the airship in addition to the continuing maneuvers of both combatants though 3 dimensions. You would probably not 'fire in sequence' like some 18th century ship of the line as the recoil from each shot will make the next one even more wildly inaccurate. A far more plausible approach would be to give each gun independent operation - the officer waits until their shot is lined up as the aircraft keep moving relative to each other, then fires. Some coordination should be made to ensure two crews do not fire at roughly the same time and waste the second shot in a wild miss, but otherwise each gun should be independent. It would take electronic controls to get your firing of different cannons across different parts of the ship to be so precisely coordinated that they all fire at *exactly* the same moment (the slightest delay would throw the shot way off). Again, firing that shot will make the aircraft rotate around its center of mass in an somewhat unreliable way - air is simply not viscous enough to push against like that. This could be somewhat mitigated with a recoilless gun - that would fit within a first world war level of technology (an approach historically used to try to get heavier ordinance on early aircraft both for the destructive effects of recoil on an airframe as well as avoiding the significant weight of a traditional artillery piece). While this does allow aircraft to use heavier guns, much of the power is spent out the back to balance the forces which cuts the effective range. If engagements are less than a kilometer you could even go with an technical setup of a modified machine gun geared to a recoilless gun or two. If the ammunition for the machine gun is calibrated to have the same ballistic profile of the big gun, you just need to walk the bullets until a spotter sees them hit, then fire the big gun. Even here you should be careful of using tracer rounds - it is difficult for the eye to perceive properly and even led to the US to stop using tracers on their bombers during WW2 as they apparently found it tricked gunners into consistently missing targets due to how the eye incorrectly perceived the shots (trust the mechanical sights, not intuitive eyes on distances and speeds your eyes did not evolve to judge well). Flak is most useful for aircraft. These basically have timed fuses - the artillery crew sets a time on them, based on a best guess, so the shells explode in rough proximity to the aircraft. Actually expecting to score a direct hit is far too difficult. In surface ships, a near miss can still be somewhat useful as the shell explodes when it hits the water, but you don't get that in aircraft - missing by just a hair is still a complete miss with no effect whatsoever unless you are firing explosive shells on timed fuses. A miss isn't even any good at telling you how close you got to hitting - it is too difficult to perceive how close a tiny fast moving object got near the target from so far away. With heavy ordinance every shot needs to count - if nothing else the sheer weight of shells you must carry is far more of a concern for an airship than it would be for a surface vessel. Visual observation should be able to use parallax to get an effective range, levels should get them an inclination, and a little calculus (easily and quickly done on a mechanical calculator) should give them a good firing solution (what angle up/down and how long before the shot should reach the target). This would still only work with very slow airships at close range - at long distances and 3 degrees of freedom, it may be practically impossible to hit. It would probably be more efficient to ditch the heavy cannon and carry that weight in bombs to drop on ground targets, while relying on small arms to defend against any light attack aircraft getting close. [Answer] My first thought was some kind of tracer round. Coat the back of your shells with a slow-burning, brightly-colored smokeless substance and follow the gaze. The problem comes in using your airship for defense, as now you will be hitting whatever is on the ground if you miss. You'll hit them with a pretty-colored piece of metal, but it will still cause damage. I would probably instead use some kind of timed-delay shell to determine the angle. You would then judge based on the position of the explosion, and adjust your next shot. Modern jet fighters (what this has been likened to) use missiles that are designed to go off at a certain range/amount of time. They do it there to limit collateral damage, but minus the speeds they travel at it could be used to aim. The way it would work is that your initial explosion to propel your shell also lights a fuse. These shells (common even in the 18th century) look a lot like the cartoon cherry bombs, and fit perfectly. The shape could be adjusted to whatever you want as well, provided you had the right chemicals on your fuse. My question to you is: Why are you depending on singular heavy shells? Some kind of grape shot or chain shot is more viable, and the grape shot can be smaller enough to prevent collateral damage. [Answer] I can't believe that no one (almost three years ago) mentioned the method of verifying range for the main gun on a tank, originating shortly after WWI and continuing until computer tracking and aiming became a thing in the 1990s. I mean the coaxial machine gun. With American tanks, this was a Browning M2 (.50 caliber, same as mounted in aircraft and used as an infantry heavy machine gun), mounted on the turret and connected to the main gun tube elevation system so it was (after adjustment at armory) aimed to the exact same point as the main gun. This was aided by having specially made ammunition for the coaxial gun that had the same velocity and ballistic coefficient as the main gun's primary ammunition (usually High Explosive Anti-Tank in those days, since that was where precise aim was most needed). With the tank dug in, there was significant advantage in getting a first shot direct hit on an enemy tank -- and this would be done by firing the coaxial machine gun. The tank commander had the trigger for this, and would call out his aiming, fire a round or a short burst, and either watch for impact or observe the tracer (both methods were used). Based on that, corrections would be made until the coaxial gun's bullets were striking the chosen target, then the main gun would fire. When coaxial guns were introduced, the first shot hit rate for tank combat increased dramatically (before then, tanks were mostly useful as low-grade mobile artillery -- low-grade because they lacked both the range and the punch of true self-propelled artillery, only barely making up for it by being armored). ]
[Question] [ I'm doing research for a space opera with some hard sci-fi elements. One faction does use radiators (dusty plasma particles held in magnetic fields- which would create the effect of glowing wings on warships) for their starships, while I'm thinking another faction would use something else so I'm open for ideas. This other faction centers on genome manipulation instead, so I figure their starships would be using something akin to biological heatsinks? Or perhaps they engineer microorganisms that could absorb heat and cool off using some sort of reverse exothermic reaction? Any ideas welcome. [Answer] 1. Thermal radiation. Read this Dec 2014 article from [IEEE Spectrum Magazine](https://spectrum.ieee.org/tech-talk/green-tech/solar/passive-radiators-cool-by-sending-heat-straight-to-outer-space) about some Stanford scientists who developed a solution to passively radiate thermal energy directly to outer space... even from the surface of the planet. 2. Re-use. Remember that [space is cold](https://en.wikipedia.org/wiki/Outer_space). Some of your generated heat will be used to heat the ships. Remember that the old Apollo missions actually had heaters on board because the equipment didn't generate enough heat to keep the astronauts warm. > > EDIT: While space's background temperature is on average -455 °F, which most people consider to be cold, the reality is that, due to the low particle count, where you are is easily heated by solar radiation. However, it doesn't change the fact that empirical evidence (the Apollo moon missions are a great start) prove that without heaters, people freeze in space. The reason simple radiators don't work is because you need somewhere to transfer the heat too, and that's where the low particle count comes into play and why alternatives are valuable. > > > 3. Finally, consider a [thermolelectric generator](https://en.wikipedia.org/wiki/Thermoelectric_generator), which is a passive device that converts thermal gradients into electricity. [Answer] **Biological or chemical heatsinks work fine for short bursts but will not be enough to cool the ship for days or months, you will eventually need radiators.** the term you are looking for is an endothermic reaction, an extreme endothermic reaction. **This already in use today it is called chemical cooling.** It is horribly inefficient but it is at least possible, and inefficient may not matter, the reactants will be continuously used up so they will still need back up radiators for when they run out of "coolant" aka reactants. **Best case they use radiators most of the time but use a chemical reaction for short periods**, but this could be a way to protect fragile radiators during combat, simply retract them and rely on endothermic reactions for a short time, then when combat is over re extend the radiators, they could even reverse the reaction and radiate the heat out using radiators to reset the system.this is heat sequestration more than anything and it has a really short working time (high mass to the amount of heat you can sequester) so you need radiators if you plan on being in space for any significant amount of time. But during combat they would not be using radiators which is the closest I think you can get to not having them at all. [Answer] Radiators on a space ship in a vacuum would have to operate by heat radiation as the other common means of dissipating heat – by conduction and convection - would not work in space. Not a radiator (but an alternative means of cooling nonetheless), would be allowing an on board liquid to evaporate into the vacuum of space. Radiators could be made much more effective by using a compression and evaporation cycle similar to that used in refrigerators. It would also be possible to connect such systems in series using different gas/liquid combinations in such a way that the final radiator became a concentrated heat source and was better able to radiate heat into space. [Answer] In order to cool off your ship, you have to somehow get rid of the excess heat. As the Three Laws of Thermodynamics go: you can't win, you can't break even, and you always lose. No matter what you do, you will generate heat that you must get rid of. Radiators are pretty much the best method for doing this. A classic radiator is just a piece of metal exposed to the vacuum of space. This includes the hull of your ship. Heat will leave the radiator in the form of infrared radiation. However, this process is slow and requires you to have rather large pieces of metal jutting out from your ship. The benefit is that it is very simple and does not require you to use any other resources. Another simple method of getting rid of your heat would be to concentrate the heat into some material with a high heat capacity, then eject it from your ship. This way would get rid of the heat more quickly, but the downside is that you would constantly be losing material. You'd have to replenish your heat sinks every so often. As some of the other comments and answers have pointed out, you can also recycle your heat. Many spacecraft, like Voyager, Curiosity, and Cassini (RIP), used radioisotope thermoelectric generators (RTGs) for power. These converted the heat from the decay of radioactive Uranium into electricity. Some of the heat is also used to keep the spacecraft warm. Now, depending on the size of your ship, this may or may not be enough to keep it cool. Your ship will radiate heat to space across its entire surface, regardless of whether or not you have radiators. Since surface area increases as size squared while volume increases as size cubed (commonly known as the cube-square law), the larger a ship gets, its surface area will increase at a lower rate. That means that if you have a small ship that only holds a few people, the heat loss from the body of the ship itself might be enough to prevent excess heat buildup. But for a large ship with lots of people and equipment, the heat will build up faster than it can be used to generate electricity and heat the ship. Even if you use some heat for electricity generation, that process is relatively inefficient, and you will always end up with more heat at the end than you had at the beginning. So no matter what you do, for a large enough ship, you will have to get rid of heat. And there are only two ways to do that in space - by radiating it away or by ejecting hot materials. [Answer] I think it would make the most sense for the biological cooling to be based off of how animals on Earth stay cool. However, animals on Earth actually tend to use natural radiators. [![enter image description here](https://i.stack.imgur.com/gyl9T.jpg)](https://i.stack.imgur.com/gyl9T.jpg) The ears of an elephant work like radiators, when the elephant is hot blood is directed to the ears, where the large surface area allows for maximum heat dispersion. Heat sinks would also tend to be ineffective on a spaceship, as without a way to remove the heat the heat would simply build until critical. Heat sinks only make sense if the heat can then be removed from that point, either because the heat sink is a thermal-electric generator like @JBH mentioned, or because the heat sink is then jettisoned. If one kind of ship were to not use radiators it might make more sense for it to be the non-biological ships that do not radiate heat. [Answer] This is an extension of @JBH's third point... Why waste your heat by radiating it out to space? Direct energy conversion from heat to electrical energy (or to chemical energy in the case of your genetic manipulators) is much more efficient. Now in a more compact form, the former heat can be stored until needed. Just because we earth-bound humans don't currently know how to do it doesn't mean it is impossible. [Answer] There are a few alternatives to traditional radiators and heat sinks, but if you are going to try to be "hard sci-fi" you don't have many real options. The "Dust radiator wings" you are describing is actually a real thing called a liquid droplet radiator. But you can induce cooling via expansion, which is much how a modern A/C works. You have slowly expanding gas "lungs" in your ship that constantly absorb heat. This is really just a fancy heat sink but it's a biological-type option. A REALLY fancy heat sink would be a trapped black hole that could absorb IR radiation. The black hole is held in a magnetic bottle and you just dump all your heat into it, never to be seen again. Obviously the energy required to hold the black hole would probably exceed it's ability to absorb heat (some of which would get blasted back as Hawking radiation) and it'd be really hard moving all that mass around (even a tiny black hole would probably mass far more than the rest of the ship, and such a small black hole wouldn't have the gravitational pull to haul in much IR radiation) but perhaps some handwaving could make this an extremely efficient, long lasting heat sink. [Answer] Anything that converts heat to some other form of energy. I suggest [light](http://physicsworld.com/cws/article/news/2012/mar/08/led-converts-heat-into-light) using LEDs. > > The device – which has a conventional efficiency of greater than 200% > – behaves as a kind of optical heat pump that converts lattice > vibrations into infrared photons, cooling its surroundings in the > process. The possibility of such a device was first predicted in 1957, > but a practical version had proved impossible to create until now. > > > The spaceships would be very, very bright, but very cool. Mind you, the conservation of energy still applies - you would have to regularly take on fuel to replace the lost energy. The general rule of thumb currently in biology seems to be that if it can be done using natural elements, then some biological process is using it. Perhaps the home planet of the ship designers have creatures that have evolved such a process for cooling themselves in a very hot environment, so radiation cooling is not an option. Like fireflies on earth use chemical luminescence. Synthesizing this biological process should be possible by a civilization advanced enough. [Answer] Consider for a moment a spaceship and how it does what it does. They get around by expelling mass in a direction opposite to how they want to accelerate. Most spaceships will lose mass over time, that's just how engines work in space. So why not take advantage of that? If you're in a fairly futuristic sci-fi setting, you're probably doing a whole lot of accelerating to get to places. Use your engine's fuel as a heat sink and pump that hot gas out of your exhaust, cooling down your ship. This way, you get a near constant way to ditch excess heat. You can do the same thing with maneuvering thrusters. These are often either gas or smaller versions of your main thrusters. If they're miniaturised versions of your main thrust, your problem's solved. If they're gas based, use water. Store it in talks, dump your excess heat in there (Water's real good for storing heat) and vent steam opposite the direction where you want to go instead of whatever you used before. If you've got a warship, you have another option: your ammunition. Presuming you're no longer reliant on old chemical weapons but have gone into the realm of rail or coil weapons, you can probably dump a fair bit of excess heat into those chunks of tungsten you're about to fling at your enemy. Same deal with torpedoes or missiles: when you're fueling them up, use your hot fuel/water and get it off your ship. They need fuel anyway and you're going to be losing the mass, so why not make use of it? [Answer] If you generate more heat than you can use (and you probably will, space is a really good insulator for all that it's also extremely cold) you will need to do some kind of radiation/dump procedure somewhere along the line, it's the intermediate steps that make the difference. Here's some options others have mentioned and some that they haven't: 1. [Thermocouples](https://en.wikipedia.org/wiki/Thermocouple) basically your heat problem makes a stop as electricity on the way to being secondary waste heat that you have to deal with. The only way these really work is if you have concentrated sources, either from concentrating waste heat somehow or from intercepting heat near source (reactor walls, engine baffles, etc...). 2. Evaporative cooling, using either the evaporation of fluid, or better yet the decompression of gas, you can soak up a lot of heat relatively quickly, especially with the gas option. Then you use compression to re-liquefy the resulting vapour and concentrate the [heat of vapourisation](https://en.wikipedia.org/wiki/Enthalpy_of_vaporization) where it can be used for a thermocouple interface. This system can also be used to either A. delay heat radiation for the purposes of stealth, simply leaving the vapour in gas phase will delay the necessity to radiate heat externally or B. to deal with large amounts of heat being dumped into the ship's internal environment, such as might occur in battle. A biological system is probably going to have an easier time with the evaporation/vapourisation option. Eventually though you have to get rid of the heat so once things reach a head and you have to dump heat externally you have three basic options: 1. Radiant surfaces, large sheets, probably composed of a Beryllium/Tungsten alloy for maximum heat capacity, that can be heated by an internal working fluid and used repeatedly and for sustained periods. 2. Sacrificial material, large shrouds, probably of a very similar material to the radiators above, of graded thickness that evaporate into space when heated by electrical resistance, or some kind of direct Infrared pumped onto or through the material. 3. Concentrated thermal emission, basically Infrared lasers pumping pure heat out into space, these can be used for communications or possibly for point defense if that's a thing in your universe. For my money any of the external options are equally appropriate for biological or mechanised systems, it's just the details that would vary. [Answer] Has anyone considered just storing the heat and dissipating it later? In some space operas, ships have cubic kilometers on mass that could be heated by a few degrees for massive heat dumping. You don't have to dump the heat externally. You don't have to assume that a ship's temperature is in a constant steady state, it could be dynamic. A biological based ship can easily do this with veins of fluid, from hot places to cold. [Answer] All spaceships doing anything interesting for any non-trivial duration need radiators. The only exceptions are orbital launch rockets, who don't spend enough time out there to matter, and satellites and probes, who only sit there, take pretty pictures and occasionally thrusting for a bit with a small, low-power thruster. Then there is everyone's favourite rule-breaking spaceship, the [Hydrogen Steamer](http://toughsf.blogspot.com/2016/10/the-hydrogen-steamer-stealth-spaceship.html). It is designed, after all, to both have long endurance and give negligible amounts of radiation, so of course it doesn't have any radiator, relying entirely on its massive cryogenic hydrogen heatsink/propellant reserve instead. As a spacecraft, particularly a combat spacecraft, its performances are rather disastrous - the same way a submarine can have rather disastrous performances compared to a surface craft. So this may give a Battle of the Atlantic feeling to your setting: one faction with conventional warships patrolling the skies, the other investing in stealthy strike ships doing their best to avoid conventional engagements. Such faction may or may not have conventional, radiator-equipped warships in addition, or may rely entirely on interplanetary ICBM-like Hydrogen Steamer missiles with high-performance terminal stages for conventional combat. [Answer] I think the answer you are looking for is solid state thermoelectric heating/cooling. <https://thermoelectricsolutions.com/why-solid-state-thermoelectric-technology/> They are simply plates made of certain materials that absorb heat and transform it into electricity. These could absorb the heat from most of your extremely hot spots like weapons, sensors, reactors, etc. And then convert them to electricity without emitting alot of heat outwards, in the process cooling the device and provididng you with usable energy. They take up little to no space and have no moving parts and are self contained so they can be used without external ship componenets. [Answer] Koolatron coolers use the peltier effect to move heat from inside the cooler to the outside using an electric current. Place peltier junctions all along the sides of the spaceship, just like these coolers. This answer has been alluded to elsewhere, but no specific mention of the peltier junction and the regular commercial use of it in coolers, used extensively today. The greater the temperature gradient from inside to outside, the greater the effect. It is like a heat pump on steroids. ]
[Question] [ In a context where downloading the brain of a person has or is about to become possible, there is a problem looming at the horizon: once there is a copy, there is the chance of getting multiple copies. While the possibility of having hundreds of Mozart, Chopin, Einstein, Fermi, Picasso and so on is surely enticing, the risk of having hundreds of Hitler, Stalin, Mengele, Pol Pot and so on would send chills down the spine of almost everybody. Is there a way to encode the downloaded brain (aka mind/consciousness) in a way that prevents uploading/using it more than once and only once? [Answer] Two simple premises: 1. [The scanning process is destructive](https://youtu.be/I0sXm08hoR0?t=201) (careful: Graphic images). 2. There is no way to store the scan other than in the next wet brain; the scan is only possible brain-to-brain. (Because no computer has enough capacity/only the brain is holographic/consciousness is a quantum state etc.) This ensures that there is only exactly one copy, ever. [Answer] # Encode Classical data in Quantum States I suspect your question is inspired by [this recent question about why uploading the mind destroys the brain](https://worldbuilding.stackexchange.com/q/240987/14322). My answer to this question uses the same principle as my answer to that question. No one can be copied because everyone is already a copy. When you are born, your brain is part classical and perhaps part quantum. Shortly after birth, the software of your brain is put it on hardware that is fundamentally quantum. Then the [no-cloning theorem](https://en.wikipedia.org/wiki/No-cloning_theorem) says you cannot be copied a second time. --- Classical data can be encoded in quantum states. For example a number $\alpha$ in the interval $[0,1]$ can be encoded by putting a particle in a quantum state $Q$ such, that when the spin is measured, it will point upwards with probability $\alpha$ and downwards with probability $1-\alpha$. What makes this encoding special is that you can never get your hands on $Q$ itself. You can only collapse it to get a single result. Up or down. The [no-cloning theorem](https://en.wikipedia.org/wiki/No-cloning_theorem) is a stronger version of this. The theorem says you can never operate on $Q$ to get an independent identical copy. After all, if we could do that, we could get a million billion copies, collapse them all and estimate $\alpha$ by the proportion of upwards pointing particles. If you have two particles in states $Q$ and $P$ they can interact with each other(or with themselves) without collapsing. This allows much more complicated things to be done compared to having to particles that each point up or down, but you don't know which. The standard example is the twin-slit experiment. Photons are put in a quantum state where they are over *here* with say 1/2 probability and over *HERE* with 1/2 probability. Even though you send the photons one at a time, you get behaviour as though there was "half a photon" in both places and they interact with each other. The brain's classical operations should be put on hardware that uses quantum states to perform the same operations. The brain uses twin slits to decide what to eat for breakfast this morning. We can see what ends up on your plate. But we cannot make a doppleganger that does the same thing without collapsing your brain into an inert jelly pudding. [Answer] ## The short and easy answer would be no. However, there are other ways to regulate. **The problem:** Moving a consciousness out of a biological "grown" environment into an artificial/digital one presents your problem. Since a digital environment has been man-made, it can be replicated. And since it can be replicated, it can be copied. If there was a sure fire way to restrict illegal copying of any kind of data, it would already be widely used by every digital content platform. Without any handwavium, undiscovered futuristic tech, or magic-type restrictions (for example there's only one "soul" that's attached to a copy) **there can be no hard restriction**. **Legal restrictions:** How this was "solved" in the TV series *Altered Carbon* was by making it highly illegal to have multiple copies to exist at once, at high penalties or even death. How the solution would work (not necessarily true to this series), is by having large government controlled facilities monitoring the copies. This would be either by directly controlling the manufacturing of the copies, or by a world wide internet-like web constantly monitoring the status of any copies currently active. **Restrictions on manufacturing:** Another way to restrict multiple copies is to have a legal or moral requirement for the digital copy to be destroyed after it is downloaded into an artificial body. This could be government controlled as above, or could run on an honour system with the companies who create the copies. **More arbitrary restrictions:** *Money:* Other restrictions you could put on the process would be time and money for example. It could be extremely costly to create and/or maintain a digital copy of a person, let alone multiple. Regardless of the positive effects this might have, it might still be too costly in the long run. *Time:* It could also take multiple years or even decades to create a single artificial human. Therefore you should be really sure that you want to create this person. It could also be that the new copies burn out very quickly and have a short lifespan. This would not only restrict the work they could do in that short time, but it would also make anyone who creates a copy think twice on whether it's worth the effort. **Effectivity:** The last thing I would consider is a more moral one. How effective would it be to have multiple copies of the same person? Would that at all work in the grand scheme of things? *Armies:* In the film series *Star Wars* there are multi-million personnel armies made of the same clone. However if we swap this for a digital clone or android, we would run into some very interesting problems. As you might know the storm troopers from *Star Wars* have been meme'd to death for being terrible shots. This isn't entirely canonical but does display a glaring problem: as soon as multiple super-soldiers would be created, someone would find their weaknesses and flaws and use it to effectively take down large swathes of these soldiers. *Dictators:* Your worry *"hundreds of Hitler, Stalin, Mengele, Pol Pot and so on would send chills down the spine of almost everybody."* is very true, it would definitely send chills down everybody's spines. However realise that most of these dictators were a product of their time and position. They got to where they were by using and abusing the troubles of their time and manipulate large amounts of people. But could they efficiently produce that position of power again? Would they be able to once again get the people behind them in a similar manner, when the people have already gotten wise to them and their methods have already been committed to history? Apart from a cult-like following, it would very well be possible that the general populace won't let them get away with that kind of thing again. Especially not if there were two of the same person, people with that kind of disposition would sooner take each other out as soon as possible rather than help each other. *Artists:* A similar thing would be true for the artists you listed. They were artistic revolutionaries of their time, and gained their popularity by charming a lot of people right then. But are they still at their height of popularity now? Would they be again? I would predict a large amount of people would label their "new" works as not "true" works. After initial hype they would not live up to the already existing catalogue. For the same reason certain bands aren't "the biggest rock band in the world" anymore despite still being around today in the same capacity. Everyone and their ideas have an expiry date, and the human body is not necessarily the only the only limiting factor for this. [Answer] Ok, we can upload/download brains, that's the thoughts/consciousness/soul/ghost of a human being. Let's sweep the practical and philosophical problems under a very thick, very large rug! Let's also assume that there can be some digital representation of a person's brain such that given proper hardware, a full brain can be reconstructed (and whatever "activate" button produces a copy of the person's mind). # Lossy Reproduction Taking a problem from data compression, you lose a bit of quality every time you incorrectly (and cheaply) copy data. Like with MP3 compression, perhaps the copies loose a bit of information every time. Maybe these losses are minor and cause quirks, like the copy enjoying vanilla more than chocolate ice cream, but maybe they are major differences, like loosing major cognitive capabilities. This is, to be honest, only a minor barrier. As we have seen with the MP3 format, this really doesn't stop people from producing copies. # The Mind is A Quantum System Although we see neurons and neurotransmitters right now, maybe consciousness (and thus cognitive abilities, attitudes, etc) rely on quantum phenomenon. If this is true, and considering interacting with quantum systems irrevocably changes them, the mere act of reading a mind interrupts and destroys the original. If the mind-downloading process is "analog" enough this raises a hard physical barrier to copies. Yes, you can position a new brain with all the bits in place from a previous scan, but when you hit "activate" some other person is created. Sure, they may have similar abilities, but most reasonable people say it is not a copy. You cannot reproduce the essential quantum phenomenon, only move it. [Answer] **Transcription is terrible.** You have one copy of Beethoven's 3d Symphony. It sounds very different each time. It is because the orchestra playing it is a middle school orchestra and a different middle school orchestra each time. An orchestra whose members have never heard the piece and have not rehearsed. These various orchestras have in common only their inexperience with their instruments and with reading music, combined with an implacable relentlessness - each of these orchestras powers through to the end each time. There is a tremendous variety in their product. There is not much worry about getting multiple Hitlers. Probably not even one. But you get something! [Answer] ## Make it physical Let's face it: electronic data is the most copyable form of information ever discovered by human beings. You're going to have a hard time making something non-copyable in that kind of format. Instead, have it be some kind of genetic or chemical material that gets output. Generate such a small sample that the act of analyzing that material is enough to destroy it or make it useless for future analysis. That way, whatever reconstruction machine you'll be using it in will only be able to use it once. If you really like the idea of having it in data, you can also do that in tandem with the chemical sample. In this case, the sample would merely act as a 'key' that would be supplemented with additional important data from the cloud - someone's brainwave pattern, perhaps. [Answer] ## Digital Rights Management Games and video services 'phone home' to check whether you're entitled to consume that media -- why would your brain be any different? Set up a simple management wrapper around the digital self that checks with external servers that no-one else is using the lease to run that brain right now before running the simulation of the person. This might lead to one or two very minor issues. * Your brain was evaporated and failed to send the "I am relinquishing the lease" message to the server. You won't be able to respawn until the lease expires. * You wander out of connectivity and the lease is going to expire before you get WiFi back. What happens? Does the management software shut you down at the end of the time? * Does your relativistic time agree with the lease server? You might be able to exploit that (or not be able to respawn for a while) * The lease server has extended downtime, and no-one can respawn. * The management software is only *mostly* unhackable, so people can bypass the system. * If you run the hacked management software, you are implicitly trusting the hackers. * You are implicitly trusting the company to decide to do the right thing. * You are implicitly trusting the company to not go out of business. * If you're a friend of the CEO of the company, you can probably just ask someone to bypass the checks, for yourself or your army of clone workers. As you can see this is a perfect solution with no drawbacks! ]
[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/202296/edit) D&D style dragons come out of the egg knowing languages meaning that they had to learn it somewhere. I'm not interested in that. What I want to know is, that assuming Dragon lullabies are like human lullabies, what would they sing about? To clarify most human lullabies are about getting the baby to quiet down and also the scary parts of the world. There's more articles about it but here's a good example: <https://www.bbc.com/news/magazine-21035103> There's also a National Geographic article that was good: <https://www.nationalgeographic.com/magazine/article/what-the-lullabies-we-sing-to-our-children-reveal-about-us-feature> What would a dragon be scared of, for the babies or the dragons, enough to sing to their eggs while brooding over them? I'm mostly interested in Ice Dragons if you want a specific type of dragon but any dragon in general will do. In my world, sixty or so years ago the air became poisonous, the poison part is just hand waving because nobody knows why other then it is in the story, to sapient creatures, dragons included, other then that it's a vaguely earth centric world up to the 1970s. After that it diverged into most people dying and people, including dragons in disguise, making out living in various manners. The three largest ones are giant walls of stone that happen to block the poison in the air, the mining quarry that mines said stone, and one place that manages to pull the poison out of the air. To clarify, the dragons are D&D style in an earth-like world up until the 1970s after which the timeline changes. [Answer] Dragons vary a lot from media-to-media, but they are always the most prideful beings in the world. How could that be different, when they are the apex predator? So, naturally, their songs would be most likely about **pride**: ``` My Little Dragonkin (sing to the tune of bayu bayushki bayu) There are those with little mouths, that can't scare bear or boar. But rejoice, we're dragonkin, and everyone will fear your roar. There are those with no claws, that can't hunt the little sheep. But rejoice, we're dragonkin, and even giants we make bleed. There are those that have no wings, that can only dream to fly. But rejoice, we're dragonkin, and you too will rule the sky. There are those that shed some tears, 'cause they know no gold nor gem. But rejoice, we're dragonkin, and you will be richer than any men. With your hoard, in your den, Greater than any elven-king. Stand with pride, show your might, 'cause you're my little dragonkin. ``` Additional themes for dragon lullabies will include things that are unique to dragons, and put them apart from the other sentient races - their claws, their ability to fly, their magic, and their overall behavior. To give some examples: * Dragon-magic is on a league of its own. Magic that is specific to dragons and *can't* be emulated by beings not-related to dragons is specially rare in fiction, and when it appears it is usually for something *big*, almost miracle-like. Obviously, not all dragons are such exceptional magicians, but the puny humans don't need to know that. So, songs that talk about magic will definitely be a thing. * Pilling up treasure is up there in the Top 3 Hobbies for the Modern Dragon. What exactly that treasure is might change from time to time, but the bottom line is that dragons are collectors of *things*. Some like shiny things (gold, gems), others like darky things (skulls, bones), others like to collect maids and kids, and so on. With that in mind, it is natural to imagine that dragons will also make songs about collecting all sorts of things and making their hoards big. * Eating. Dragons can eat *almost anything*, including a lot of things that *shouldn't* be edible. Dragons don't remove the stupid metal peel of a knight before gulping them up - the poor sod just goes in whole, and the magically-enhanced stomach acid does the rest. So, songs about eating things - be it plants, animals, or other sentient beings will certainly be a thing. I can easily picture songs with themes like a dragon trying to grow big enough to eat very big things - like a tower, a castle, or the moon. * Dragon Anatomy. Dragons are very different from the usual creature - they have six limbs instead of four, they look like reptiles but are built like cats, they have long tails and powerful claws, mighty teeth and a powerful breath weapon. Songs that name those things, sang by the dragon-mom while she boops the respective wyrmling's body parts can easily be part of the repertoire. * Dragon smells. [Apparently a lot of time was wasted by several authors to write about how dragons smell like.](https://rpg.stackexchange.com/a/151881/11162). If you subscribe to the idea that each type of dragon has a specific smell, then memorizing what type of dragon smells like what can help dragons identify each other on the field, specially if they do disguise themselves like humans to keep a low profile. [Answer] **Mathematical progressions.** Ice dragons are asocial. They do not care about other creatures, or other dragons. They do not have familial or filial attachments. When the young dragons fledge, they will not look back. Ice dragons have none of the sociocultural baggage humans have. They have no need for education that is friendly, or funny, or serves to reinforce their cultural identities. Ice dragons are rational. They understand physics and that the world moves in ways that can be understood. Ice dragons do sing. Their songs have no words. The ice dragon mother sings pure tones. Then she changes the pitch by multiples of the frequency up and down. The ice dragon mother sings pure tones. She changes the rhythm by multiples up and down. The ice dragon mother sings chords. Then she changes the chord to those chords which are relative to it. Through her songs, she teaches the new dragons math, and rhythm, and the immutable relationships of things that can be precisely known. [Answer] **Ice Dragon Lullabies Sing to a Harsh Existence** Ice Dragons by nature of their extreme and inhospitable environment may have a culture focused on survival, efficiency of energy, and sensing. Because they are adapted to the frigid environment, their prey are generally less plentiful, and so food, and death by starvation (as opposed to other life forms’ focus on falling from trees, or death by pandemic and burning) may be their drive and fear, respectively. Ice Dragons, to assist in catching the rare prey in their harsh environment, will have some specially adapted sensing which might be the source of lyrics. They are of course, well adapted to harsh winters and will have natural affinity to sensing their surroundings. Even during the harshest ice storms, they will be adapted to survival. They may be attuned to sensing heat signatures, or have mastered hearing sufficient to filter out noises by the wind to better pinpoint needed food. These traits will be valued for continuation of the species. I would imagine Ice Dragon lullabies and nursery rhymes to perhaps: 1. warn of starvation, or mock death by starvation; 2. praise strong senses; 3. edify survival; 4. value efficiency; 5. mock as weakness temperate climates or those who live there. Their surroundings are brutal, and so will be their songs. Some examples: Scottish lullaby about loss: > > Hovan, Hovan Gorry og O > I’ve lost my darling baby, O! > > > Italian lullaby about giving baby up (for example if not enough food can be provided for it), which has ice-centric theme also as its final hook: > > Ninna nanna, ninna oh. > To whom shall I give this baby? > If I give him to the old hag, she’ll keep it for a week. > > > If I give him to the black ox, he’ll keep it for an entire year. > > > If I give it to the white wolf, he’ll keep it for a long time. > > > A brutal Malaysian lullaby, Lima Anak Ayam, could be retooled to Ice Dragon eggs: > > Five chicks > One chick dies > > > One chick dying leaves four > > > A Danish lullaby captures a similar hard-scrabble existence: > > Dad is working very hard, Mum has to help. > Hans cries again and again when she has to leave. > > > We have to work to earn a living. The children will suffer. > > > We cannot give them any better even though we want to. > > > The Turkish lullaby, Incili Bebek Ninnisi, is a great example, telling the story of a man who promised to sacrifice three camels if his wife could have a child, but then decided to renege and keep the three camels after she gave birth. An eagle then carried the baby off and tore it to pieces. The song is from the perspective of the grief-stricken mother: > > Above black eagles wheeling, > All of a sudden swooping, > > > My little baby stealing, > > > Sleep, little baby, sleep. > > > Above black eagles soaring, > > > A crown of pearls left lying, > > > Your stupid father snoring. > > > **Dragon Lullabies Generally** Human lullabies, by contrast, focus on boogeymen or animals stealing a baby, or a cradle falling from tree, or just the stars above. Dragons aren’t generally going to embrace the boogeyman genre of lullabies — dragons are generally at the top of the food chain, unless their boogeyman is an abysmal fiend, Demi-god, or god. Physical suffering, like falling from tree isn’t a worry, especially when you have wings. And they can fly to the air, although twinkling stars — unreachable to even earthly-bound dragons — still might hold some wonder. [Answer] **Statistically speaking, killing invading humans.** [![Sing a happy elf song](https://i.stack.imgur.com/sxEpN.jpg)](https://i.stack.imgur.com/sxEpN.jpg) [![human:all happy elf and dwarf songs are about killing invading humans.](https://i.stack.imgur.com/u4Lcf.png)](https://i.stack.imgur.com/u4Lcf.png) [Answer] ## The mother would not sing to the eggs In the womb, a human fetus is exposed to the constant rhythm of the mother's heartbeat, the squeeze of the uterus, the bob of the mother walking, and vibrations caused by the mother's muffled voice. The absence of the familiar sounds and feels of the womb are disturbing to a human infant, and things that recreate this environment are comforting. So, when a newborn is crying, we instinctively do things to recreate these feelings like swaddling, rocking, shushing, and singing. Focusing on the singing part: When the fetus is in the belly, the mother's voice creates vibrations that don't happen outside of the amniotic fluid; so, we have to try extra hard to create vibrations to soothe the baby. What a newborn baby actually finds soothing about singing is the vibrato; so, if you hold an infant to your chest and do a deep throat song, it is actually WAY more effective than singing a higher pitched song with words. However, it only takes a few weeks for the baby's comfort cues to transition from just vibrations to be the actually singing at which point it becomes the singing itself that is comforting. The thing about eggs is that the babies are still in a liquid at this point in their development meaning they will still get the same vibrations through normal speech as they did inside of their mother; so, if we assume that mother dragons care about comforting the babies developing in the eggs, then as the mother dragon sits on her eggs to keep them warm, she would probably resort to telling them stories rather than singing them songs. It would only be after the eggs hatch that a mother dragon's parenting style might transition to using song as a source of comfort. ### So what stories would they tell their eggs? When we look at human lullabies we sing about everything from far away times and places, to mundane actives, to total non-sense, to babies falling to their deaths... the same is true of bedtime stories. Since bedtime stories and lullaby's are more or less the same thing in different media, we can use their structures interchangeably. While the OP is right to identify that these stories (and lullaby's) focus on scary things, it is not to scare the child, but to establish a since of consequences for unacceptable behaviors. Goldilocks is eaten because she vandalized someone's home. Little Red Ridding Hood is eaten because she talks to strangers. The 2 of the 3 little pigs are almost eaten because they were too lazy to prepare properly. Icarus falls to his death because he does not listen to his father's advice. In some cases, the natural consequence to an unacceptable behavior is exactly what makes the behavior unacceptable. And in others, a "Big Bad Wolf" archetype is inserted to create a consequence for socially unacceptable behaviors that in reality rarely have actual consequences other than pissing someone else off. The most obvious thing of natural consequence in your world is the poison gas. There will be a lot of stories about baby dragons wondering into the gas and dyeing... but there will also be taboos. Maybe baby dragons are not supposed to go out while the mother is asleep, or maybe they should not pick their teeth with their tails, or maybe they are only supposed to eat sheep head-first. So, what happens to these naughty little dragons? Well the "Big Bad Wolf" archetype represents the single greatest threat we USED to have but still persists in our social consciousness; so, your dragons may remember the time that humans were numerous and had guns, and missiles, and fighter jets, etc. So, even with the threat of man being gone, the stories of "men with guns" will persist, and even become embellished for thousands of years. "So remember baby dragon, if you don't eat your vegetables, the men with guns will come and shoot you out of the sky." [Answer] ## They would sing about the many dangers of the world, and the satisfaction of growing too large for those dangers to harm you. DND dragons seem to be very much an R-type species. They have very little to fear as adults, but as a hatchling or young dragon, the forgotten realms are a very dangerous place. There are numerous monsters able to overpower a young dragon, especially in great numbers. In addition, there are murderous adventurers and larger dragons to fear. However, if a dragon survives long enough to reach adulthood, most of those dangers become nothing more than food and playthings. Even a coordinated army of human, elf, and dwarf soldiers would struggle to bring down the largest dragons, especially if the dragon mostly stays in the air. As such, a fitting lullaby for dragons, especially antisocial white dragons would be about all the perils of the world, and about the glory that waits for those who survive. [Answer] # Other chromatic dragons would maybe sing, but probably not ice dragons. Silver dragons would definitely sing about humanoids and their cultures. Copper dragons would probably just tell its eggs jokes or sing to them about the importance of a high-spirited happy life, since they're fans of puns and pranks. Brass dragons would probably talk to their eggs. Very, very regularly. They crave conversations to an almost unhealthy extent (yet they seek desolate places, they're a bit paradoxal). Going more strictly according to dnd descriptions of the dragons, you'd probably have a scenario where no dragon type is the same. Chromatic dragons are usually more "evil", that is, they're more self centered and prideful in a way that's diminishing to everything else. Metallic dragons on the other hand are much more good aligned and less centered on themselves. This means that, by dnd standards, each dragon would probably behave towards their eggs in a way that reflects the ideals and morals of its kind. Going by that, we could approximate more or less what the songs would mostly be about: Golden dragons would sing about growing wise, but humble, helping others and similar virtues. Silver dragons (the good ice dragons) would sing about distant lands and cultures and all the beauty the little one can find in them once they're ready, as well as how much more than mere gold creatures seemingly so frail can offer (because silver dragons basically love seeing and experiencing the culture of the many humanoid races, to the point their hordes are usually composed in good amount of things like human artifacts and items with strong cultural value). Bronze dragons would sing about the oceans, sea shanties and events that took place among the waves. Chromatic dragons on the other hand would probably have songs less about others and more about themselves. The prideful red dragons would sing of their feats, about the need to grow strong and defending their pride as members of a species second only to the gods themselves. Green dragons would sing praises of one's knowledge and cunning, the power of speech and how the strongest barbarian can dance like puppets In the palms of those who know what to say and when. The greedy Blue dragons would sing of glorious hordes, the importance of gold and all that's precious over the lives of others and treasures they expertly hid under the sand (treating its children like a kind of treasure might not be totally out of bounds for them either). Black dragons could sing of their children growing powerful and showing their might to the world, of the seed of destruction they carry within, as well as tales of foolish adventurers who overestimated themselves over the might of a black dragon. The bestial white dragons (the more classic "ice" dragons) are the exception. They're naturally more animalistic than the others, prefer to be solitary and rarely speak, but take the most pride in their achievements through sheer might (to the point trying to bribe one by offering something feels like an insult to their ability to simply take it). Due to this, I believe they'd be much more like an alligator and a bear in behavior. It wouldn't sing, it'd simply hum constantly to let their babies know that it's close and there to help them. White dragons have pristine memory and can recall things almost perfectly, so to such a creature that values strength over all, I'd say the biggest quality a mother could have would probably be to be strong enough to be capable of always being there for its offspring, because it's babies would probably be able to remember even at its death bed. ]
[Question] [ Altheia is the City of the Copper Folk. Its bishops and wise dictators believe that copper is the metal of gods, a holy item given to Altheians as a gift for their religious behavior. **Edit to clarify** > > The actual reason behind this belief is that in Altheia deaths have been lowered since the implementation of copper in daily life, mostly due to an increase in levels of hygiene as copper kills most bacteria, thus it was seen as an holy miraculous metal gifted from the heavens. > > > In Altheia everyone dresses in clothing made of copper. The clothes are not too heavy and they are certainly not armor but some small plates are used, not for protection but as decorations and accessories. The territory of Altheia is so rich in copper that even the streets resemble blue oceans due to their bricks being made out of copper. But there's one problem: the technology level of Altheia is similar to that of the ancient Greeks during the Roman empire. How can they make copper clothing, if it's even possible? [Answer] # With enough effort, definitely It's not just a matter of having enough copper. They also need resources, especially labor. Working copper into this format doesn't require very advanced technology and the ability has been shared by many cultures through history: > > Copper was probably the first metal used by ancient cultures, and the > oldest artefacts made with it date to the Neolithic period. The shiny > red-brown metal was used for jewellery, tools, sculpture, bells, > vessels, lamps, amulets, and death masks, amongst other things. So > important was the metal in human development that it gave its name to > the Copper Age, today better known as the Chalcolithic. ([Source](https://www.ancient.eu/copper/)) > > > You need very thin sheets of copper to make clothing. Some of the [Mississippian copper plates](https://en.wikipedia.org/wiki/Mississippian_copper_plates) (replicas below) weren't that far away from what you'd need and they were made with a relatively low technology level. [![Mississippian copper plates replicas](https://i.stack.imgur.com/THBMR.jpg)](https://i.stack.imgur.com/THBMR.jpg) The real challenge comes from crafting enough plates to clothe an entire population. If you have enough skilled people to run a large manufacturing operation, you could make it work. [Answer] A "simple" method would be a single robe made of copper, rather than separate shirt-and-trousers. In 2012, Indian businessman [Datta Phuge](https://en.wikipedia.org/wiki/Datta_Phuge) commissioned a shirt made of gold. This took a team of 15 goldsmiths working for about 2 weeks to create! Since the Romans made both jewellery and [chainmail](https://en.wikipedia.org/wiki/Lorica_hamata), they should have the technology to do the same thing (although, not necessarily quite as fast) ![Datta Phuge in his Gold shirt](https://i.dailymail.co.uk/i/pix/2013/01/04/article-2257209-16C051F1000005DC-920_634x822.jpg) This shirt weighed about 7.3lb / 3.32kg, so your "not too heavy" requirement might be in trouble - let's examine that. If we assume that a robe would require approximately twice as much metal, then Gold would require about 14.6lb / 6.64kg. A "reasonable" backpack load for someone of Datta Phuge's size would be 12-18lb / 5.4-8.16kg Gold has a density of $19.32g/cm^3$. Copper has a density of $8.96g/cm^3$. As such, making the robe from Copper instead of Gold would weigh 6.77lb / 3.08kg - this is lighter than the Gold shirt is, but still not something I'd look forwards to wearing all day! However, beyond just the weight, I think that you would need to worry about chafing, and getting pinched between the links as they shifted around! Your citizens would probably want to wear undergarments made from a normal, more comfortable, fabric beneath their bling. [Answer] If you're prepared to let your civilisation discover a little chemistry/alchemy then it's possible to electrolessly (chemistry only, no electricity needed) plate metals such as copper onto fabrics such as silk (very fine woollen fabrics would probably work too). I don't know if it would work on cotton or other plant-based fabrics where the fibres are absorbent. A similar fabric is available today, with copper plated onto nylon/polyester, and is used for electrical screening or earthing (for example in suits worn in [Clean Rooms](https://en.wikipedia.org/wiki/Cleanroom)). I worked with this fabric back in the late 90's when I was working on wearable electronics (at Philips Research) and it comes off the roll looking just like fresh copper, with a beautiful peachy-orange glow, that then dulls down to a darker orange over time. The copper is on the surface of the fabric to ensure high conductivity so it'll also work for your anti-bacterial purposes. Being plated, the copper layer is very thin and so won't survive a lot of polishing. Clothing made of it will gradually dull over time, though a quick dunk in some acid (nothing complicated needed, lemon juice will work) followed by a rinse in water would restore the shine, at least for the first few times. [![Copper plated fabric](https://i.stack.imgur.com/zDMMl.jpg)](https://i.stack.imgur.com/zDMMl.jpg) (From <http://etextile-summercamp.org/2016/conductive_fabric/>) I can't find a free to view reference on the plating process, so either use your favourite scientific paper downloader to get this paper: [An alternative process for electroless copper plating on polyester fabric](https://link.springer.com/article/10.1007/s10854-008-9594-4), or just look through the references, which are free, and see if you can find one that's available to download. [Answer] If sufficiently pure and/or frequently annealed, metal wire can be knitted or crocheted. [Arline Fisch](https://en.wikipedia.org/wiki/Arline_Fisch) is particularly adept at this. Here is a glove woven from fine copper and silver wire: ![woven glove by Arline Fisch](https://i.stack.imgur.com/jCuN3.png) <https://americanart.si.edu/artwork/bracelet-and-glove-71852> [Answer] Given the age of technology, it does sound like they'd be familiar with metalworks and how to get the metal. If they want to wear it like clothes, they'd need to find ways to refine to smaller sheets to keep it lightweight or turn it into a weave/wires that went with other fabric weaves as the clothes were made. This could be something they had learned more advanced than we did here given they had plenty of access to the abundance of ore. Year's worth of metalwork could produce paper-thin plates that were near-weightless that could be sawn as panels onto a fabric shirt so the skin wouldn't get irritated. Skills would get passed down by tailors and metal-workers that's no doubt have a share in the business. How they're made...they would no doubt melt down the ore into smaller, flatter shapes for specific things, like a circle or square and use a hammer to thin it out, as a blacksmith would do. Casts and molds wouldn't be too hard for a starting point. ]
[Question] [ One day, on the faraway world of not-medieval-Europe, someone discovered that a type of stone could be made to float. A decade or two later, there are flying castles, built out of and/or on a foundation of said floating stone. Floating stone doesn't actually float everywhere. There are large lines (let's call them Ley lines) crisscrossing continents and oceans, where stone floats best on, separated by voids where it doesn't float much, or even at all. Altitude above ground also weaken the effect, so you won't see floating castles more than a few km up at most. If a floating castle drifts away from a Line, it will (hopefully) gently float down and land - though "gently" at the scale of a castle can still be potentially fatal to anything both in or under the castle. **What propulsion would be used on a floating castle with medieval technology?** Standard airship techniques may not work, as flying castles are so incredibly denser and more massive. Ideally, it would allow for a fair bit of control, to avoid getting pushed out of a Line or into a mountain. Available tech can be from late Roman to mid-late medieval era. There is no magic apart from floating rock, and it doesn't really scale down. On the other hand, there have been a few decades with incentives to solve new problems, so new tech can be used if it could have reasonably been invented in those conditions. Likewise, flying castles themselves can help in engineering projects, for example to (slowly) move very large charges up. The following numbers and assumptions are given as a baseline, but can be changed if it makes things more interesting: * The two main things moving a drifting floating castle are wind and natural currents from the Ley line. Generally, the Ley current is weaker though not negligible, and constant on one place. A castle can also very slowly gain and loose altitude. Assuming no ballast drop, a castle can accelerate at about 5 cm/s², with a max ascending speed of 2m/s, in good conditions (descending speed is limited only by lithobraking). * The largest flying foundations are roughly 30m radius circles, with 20m-thick foundation. The smallest ones are 8m radius and 6m-thick foundation. The foundation itself is at least 9/10 filled in stone, but there are often small chambres and tunnels for access below. There can be light structures hanging from under the foundation, though most of the mass must be over it. * Floating stone has a density of about 2.5 g/cm³. So the biggest castles have a foundation of about 150,000 tons, and the smallest of 3,000 tons. (If other properties are needed, we can use granite as placeholder) * Total non-floating-stone carrying capacity of a castle is about 1/3 of the stone mass, for the best-built (and most expensive) models - so 1,000 to 50,000 tons. * To save on capacity, walls can be partially built with floating stone, up to about 1/3 of the mass of the foundation. Those walls must be at least 1m thick, but don't count on carrying mass and can be used as support for other structures. * Flying castles typically have a smaller slab inside, in a long vertical shaft, capable of independent vertical movement. It is usable only when there is little to no horizontal acceleration, and with a max vertical speed of 10 cm/s. It can be used to raise about 1/30 of the mass of the foundation (so 100 to 5,000 tons). Some people are experimenting with cisterns at both ends, using hydraulic power from the upper cistern, then raising spent water from the lower to the upper one. Not sure how well this scheme would work - this would be the subject of another question, but consider that there is some power available from this, if it can help. [Answer] You should work on the physics behind the floating rocks. What is the principle that makes them float? We know that the force of the stones is parallel (but opposite in verse) to the gravity, so it alway points toward the sky. This means that the rocks can only make the castle stay afloat. In order to move the castle, you need a force that can be addressed, with a parallel component with respect to the surface. You said that, far from the Line, the floating power of the rocks gradually vanishes, as well as it is weaker the higher you are from the surface, so we can make some assumptions. Everything sounds as if there is a repulsive force from the ground (1), as well as a material that can dampen the force toward the sky that is generated by such stones (which should be plentiful far from the Line). Now, let's say that I can shield my floating stones: [![enter image description here](https://i.stack.imgur.com/U2Yy8.png)](https://i.stack.imgur.com/U2Yy8.png) *The mortals tremble in the presence of my superior Paint skills!* An unshielded stone, receives repulsive force from all directions, so that all the components parallel to surface cancel themselves. A shielded one, receive only the forces from one direction, so that it has a smaller component toward the sky, but also a component parallel to the surface, pointing in the opposite verse with respect to the opening in the shielding. So, a castle could have some big unshielded stones, mainly used to keep everything afloat, and one or more partially shielded stones, mounted on joints that can be orientated, to propel and steer the castle itself. (1) But let's be careful: the repulsive force from something that can be approximated as an infinite plane would be the same at every distance from the plane itself (in other words, it wouldn't fade with height). I suppose that the Line is thin enough that the ground under the castle can't be considered an infinite, repulsive, plane. [Answer] Brute force. Lots of inertia in a castle, so you'll have problems making an engine sufficiently powerful to drive a propellor to move it along, even if you had substantially more advantaged technology than was generally available in the medieval period. Therefore, brute force. One means of brute force is to just get a lot of slaves on the end of ropes. This might be a good reason to get back to the good old loot'n'enslave warfare that was so popular back in the axial age. A slightly less ethically challenged option would be to use lots of draft animals... oxen would probably do, because you don't want to get up too much speed with a castle. Another possibility is to use anchors and capstans, and use mechanical advantage to haul your castle up towards an anchor, and then (slightly less) brute force to move your anchor points in the direction you wish to go. You might have to use this method to make headway against very strong winds, and you'll definitely want to be anchoring your castle in place when you're not moving it around. There's a minor additional benefit here in that you could perhaps fire a lightweight anchor via a siege weapon, and therefore be able to haul yourself along without actually putting troops or animals on the ground. This would be useful for navigating hostile or otherwise impassible terrain such as mountains, swamps or shallow lakes and rivers. [Answer] ## Ley-Line Canals [![An image of the Segovia Aqueduct](https://i.stack.imgur.com/srJst.jpg)](https://i.stack.imgur.com/srJst.jpg) <https://commons.wikimedia.org/wiki/File:Segovia_Aqueduct.JPG> Your castles may float along dedicated canals which are specifically built to allow for floating castles to navigate them. The Romans famously built aqueducts for transporting water, if you built something similar, it would allow for you to easily transport your castles around. The canals would be constructed along the paths of the ley-lines, essentially acting as guides to prevent the castle from drifting away from the ley-line. This also means you will not accidentally drift into a “dead zone” where the stones do not float at all, which would cause a castle to crash. **Sails** Canals alone though wont cause you to move forward. Instead, as you are now floating along fixed lines, like a railroad track, you can now safely use sails to push you forwards. Before, without he canal, you risked being pushed out of the ley-line. Now though, as you are more firmly fixed into the line, there is significantly less of a chance for you to be pushed out, most momentum from the wind should push you forwards (assuming you angle your sails correctly and the wind is not blowing in the complete opposite direction you want to go). **Wheels** Alternatively, you might opt to use wheels to move your castles. Wheels would run along grooves in the canal and could be powered through a number of ways, such as by man power, using beasts of burden or even with falling water like a watermill. Don’t expect the castle to move particularly quickly though. One problem with the concept of using canals though is they would take a very long time to build everywhere. Perhaps you only have canals on major routs, such as between cities (much like how highways only run between large cities and smaller towns build up along those routs). You could also take from the idea of shipping lanes where canals are only built on well-established and often used routs. ## Magnetism Essentially, your castles could work like [levitating trains](https://science.howstuffworks.com/transport/engines-equipment/maglev-train3.htm). Your stones would work like magnets, repelling away from the ley-line which causes them to float. If you can invert that signal, causing them to be pulled towards the ley-line rather than being pushed away, you could propel yourself through the power of magnetism (not really magnets per se but they function similarly enough). The way magnetic trains work is by turning on and off magnets in a certain order, causing the train to be pulled forward. Your stones could be turned on and off, when they are on, they float on the ley-line, when they are off, they fall. So how can we turn this into forward movement? Well if we start with all of the stones being turned on, the castle will be floating and relatively stationary (barring the flow of the ley-line and the wind pushing it). What we do next is turn off the stones at the front of the castle, only for a fraction of a second, which will cause the castle to tilt slightly forwards. The force of gravity will start pulling the castle downwards on that side, pulling it forward. To prevent us from crashing, we turn the stone back on, floating us back up, only now we are slightly further forward. If we keep repeating this process rapidly, we will soon start to build up significant speed, despite the castles high mass. This concept is very similar to that of the [rail gun](https://en.m.wikipedia.org/wiki/Railgun) which uses electromagnetic force to move a metallic object at high speed. Contrary to its name, it is not just intended for weaponry, [NASA proposed to use a rail gun to accelerate small aircraft or spacecraft into orbit.](https://www.popsci.com/technology/article/2010-11/nasa-engineers-propose-combining-rail-gun-and-scramjet-fire-spacecraft-orbit). [Answer] **Tracks.** I wondered for how long people had been using rail-type tracks to move cargo overland. A long time: I found the Diolkos, used by the ancient Greeks to move ships overland. <https://en.wikipedia.org/wiki/Diolkos> > > The Diolkos was a trackway paved with hard limestone[26] with parallel > grooves running about 1.60 metres (63 in) apart.[31] The roadway was > 3.4 to 6 metres (11 to 20 ft) wide.[26] Since ancient sources tell little about how the ships were hauled across,[24] the mode of ship > transport has largely to be reconstructed from the archaeological > evidence. The tracks indicate that transport on the Diolkos was done > with some sort of wheeled vehicle. > > > Your ley lines would have parallel tracks along them, probably of stone. Stays down within the tracks would prevent upward motion of the castle and having two would prevent lateral movement out of the influence of the ley lines supporting power. The castle would be moved by sliding the stays along the tracks. A team of oxen could do this, in the same manner an ox team might pull a barge. Depending on the distance between the two stays you might need 2 teams working together. You could do away with the stays and rails and just use the ox teams but you would need to have a cart heavy enough to oppose the lifting power of the castle which is more work to move. [Answer] What instantly comes to mind is: **WATER** Water can be collected from rainfall in a cistern within the castle. You could then easily direct the flow of the captured water, and with water being relatively dense it would have the kind of propulsion you're looking for. Since there is mechanical power available to these castles as the question stated, you could also manipulate the pressure at which water is propelled. Think of it like an ancient fire hose, which can output water with an immense amount of force. [Answer] They have lifting stone in '[The Edge Chronicles](https://edgechronicles.co.uk/)' and ships all employ a Stone Pilot to carefully control the temperature of the ship's stone. Hot stone rises and cold stone falls, but differential heating can be used to angle the lift vector and push the ship along. High performance stones have carefully bored holes, to allow fire (or cooling air) to reach the middle of the stone. Most people understand the concept, but only the stone pilots have the finesse to safely control a ship. [Answer] Take a look at the work of Leonardo Da Vinci, he covered a couple of designs related to flight such as a man powered machine with mechanical wings, and a aerial screw. Either of these could potentially by modified and increased in power and size to assist in moving a floating castle. They would obviously need to be massively increased in size and efficiency to move something so massive though. Horse powered treadmills could provide the mechanical energy. As you said, they've had a few decades to improve on initial solutions so perhaps they may have increased to the point of developing a reasonable propeller. Remember too that the ancient Greeks developed the first steam engine, but saw it as a toy rather than as something that could be used as a tool. [Answer] Fun fact about late Roman technology: They had all the tools to make a steam engine. <http://www.foresightguide.com/50CE-a-steam-engine-in-ancient-rome/> Steam engines are useful for a lot of things, and would help with several of the previous answers. Whether you're going on water or land having a steam engine would help enormously. That may be a bit steampunk, and it assumes that the knowledge wasn't lost (they were called the dark ages for a reason), but steam turbines and propellers could definitely move your castle along the line. ]
[Question] [ In my fantasy world, I have created a sentient species descended from an arboreal felid (it evolved to eat squrriels and small monkeys). They are my elves. The one problem is that I want them to be herbivores. So I would like someone to help me figure out why a carnivore descendant would do this. This world has natural magic, which sort of radiates from magical sources such as mana springs and arcanacrystals) so feel free to use that in your answer. [Answer] You could start with the panda pattern. Giant pandas are carnivores which have adapted an all vegetarian diet. **Your elves are also pandalike fallen carnivores.** <https://en.wikipedia.org/wiki/Giant_panda> > > Despite its taxonomic classification as a carnivoran, the giant > panda's diet is primarily herbivorous, consisting almost exclusively > of bamboo. However, the giant panda still has the digestive system of > a carnivore, as well as carnivore-specific genes, and thus derives > little energy and little protein from consumption of bamboo. Its > ability to digest cellulose is ascribed to the microbes in its gut. > Pandas are born with sterile intestines and require bacteria obtained > from their mother's feces to digest vegetation. The giant panda is a > "highly specialized" animal with "unique adaptations", and has lived > in bamboo forests for millions of years. The average giant panda eats > as much as 9 to 14 kg (20 to 30 lb) of bamboo shoots a day to > compensate for the limited energy content of its diet. Ingestion of > such a large quantity of material is possible because of the rapid > passage of large amounts of indigestible plant material through the > short, straight digestive tract. It is also noted, however, that such > rapid passage of digesta limits the potential of microbial digestion > in the gastrointestinal tract, limiting alternative forms of > digestion. Given this voluminous diet, the giant panda defecates up to > 40 times a day.[56] The limited energy input imposed on it by its diet > has affected the panda's behavior. The giant panda tends to limit its > social interactions and avoids steeply sloping terrain to limit its > energy expenditures. > > > Your elves would eat all the time and be large, sluggish, antisocial and productive of large quantities of splintery feces. That is pretty much elves, I think. Pandas just stumbled into the bamboo forest and started eating. The bamboo probably does not get much from the deal. I think if your elves are intelligent it offers another more conventionally elvish property. **These elves are gardeners** in the manner of the acacia tree ants. <https://news.nationalgeographic.com/news/2013/11/131106-ants-tree-acacia-food-mutualism/> > > Trees Trap Ants Into Sweet Servitude > A sip of nectar enslaves ants to the trees they guard. > > > The elves grow and protect the trees, and in return the trees give them leaves and sugar. Like the ants, the elves are totally addicted to the leaves and sugar from this particular tree and so must carry supplies with if they travel. Fortunately the sugar and leaves ferment very well, providing concentrated calories and thus even though the elves are large, sluggish and antisocial the elf liquor helps them overcome this with wild dancing and parties. The drink is also addictive to nonelves. If humans partake, they might find themselves dancing at an elf party until the drink runs out. That takes a long time. [Answer] **The Carnivore Energy Trap** The problem with being a Carnivore is that meat is energy dense, and more readily digested. Whether they hunt small or large prey, it means that they have to hunt fewer times, which is a great cost saving in time and energy. They can have smaller more streamlined digestive systems which takes less space, weighs less, and consumes less energy. These cost savings allow for a host of other adaptations that make them better hunters. These adaptations also make existing on other food much harder. The streamlined gut reduces the nutrition extractable from less easily digested foods. Hunting adaptations cost energy and offer little benefit when browsing for vegetation. In short, trying to become a herbivore again, requires sacrificing on what is easy. **Ways out of the trap** *Survival.* Those that are alive, are those that found a way to survive where others didn't. Congratulations your felids were the ones that didn't die. They did it by changing their behaviours, and adapting. The first of the omnivours identified a relatively nutritious plant/plant parts. This could have been fruit. They gained access because they were more than scary enough to displace any other herbivore. Eventually the range of nutritious plants broadened as they adapted to eat harder food stuffs. *Intelligence.* At some point your felids became intelligent. If they were moderately intelligent earlier in their omnivore days it would be better, but any point would do well - except already being 100% herbivores. The intelligence required is not counting, language, or anything terribly complicated. I'm talking about the intelligence required to work with fire, and specifically how to cook with it. It would have had a similar effect for them as it did for us humans. Suddenly inedible foods are now safe, and nutritious. As to why fire did not herald a new age of predatory behaviour is going to be a tough sell though. Fire opens a lot of door-ways including weapons, and improved hunting tactics. Either have all the mega-fauna be extinct, or make it so that mega-fauna are quite powerful. I'm thinking dragon class here. Very difficult to kill, very likely to wipe out entire clans, almost impervious to sharp weapons, ignorant of fire, and foul tasting (even when cooked). As for other smaller prey, make them scarce, or make them exceptionally hard to hunt even with advanced tools and fire. You will have a few still hunting but the art will slowly fade from the culture as more and more individuals support themselves by gathering and eventually farming. At the same time have fire open up even better tasting, and nutritious plants. [Answer] The change from carnivorous to herbivorous is not likely to happen quickly. For example, it would be unlikely for intelligent carnivores to just *choose* to go vegetarian as they wouldn't have an even approximately appropriate digestive system. You would end up with a bunch of sickly, lethargic and grumpy Elves. What could happen would be a gradual evolutionary change from carnivore to herbivore - more likely if they were already partially omnivorous. This could be due to environmental pressures. For example, repeated boom/bust in squirrel population means that only the more omnivorous felids survive periods of starvation. Then either some environmental disaster totally devastates the squirrel (and monkey) population so felids go totally vegetarian, or now social/religious/ethical drives could push them in that direction. As a real-world example, consider bears - polar bears are almost totally carnivore; pandas are totally herbivore; but they both descend from the same ancestral proto-bear. But you are probably needing many thousands of years (possibly up to millions) for this to happen. [Answer] **Farming and direct choice** It is a lot easier to farm plants than it is to farm animals, and easier to store them as well. You don't have to feed the dried apples you have in your storehouse over the winter. Cattle still have to be fed, which means you're growing and storing the food anyway. Instead of evolving this way, your elves deliberately *chose* this path. While they may have been carnivores or partial omnivores, they steered their culture towards farming - And while obligate carnivores *require* meat, your elves were able to harness the nature magic to change their whole physiology to accept and thrive on plants - And to have those plants produce more and better nutrients. This is why elvish travel bread is *so* good for its size. [Answer] The Elves evolved from arboreal felids to herbivores due to a combination of their intelligence, dwindling food supply, gut bacteria, and culture. The primeval elf was a highly intelligent tool user that hunted the other arboreal creatures to near extinction. Their use of pack tactics, tools (spears, bow/arrow, etc), and high intelligence allowed them to continue constantly increasing in number past what their food supply could sustain by becoming more and more efficient at hunting the remaining animals. When the tree-dwelling animals were hunted to near extinction they moved to consume land-based animals which they also drove to near extinction. When the great famine finally came it was vicious, the Elves would kill and eat anything that moved and would devour every portion, skin organs, everything. They had taken to the practice of eating any animals they caught immediately, raw and whole to prevent the food from being stolen by fellow elves. This was the beginning of the turn around for the elven race. By eating the stomachs and intestines of herbivores raw they incorporated the gut bacteria of their victims with their own and were able to a limited extent able to start effectively digesting the abundant fruits in the area. Over time the elves evolved to be able to handle a fully plant-based diet via natural selection while the animal populations in the areas they lived in recovered. The elves never forgot this part of their legacy which they carried on via oral tradition for hundreds of years which shaped their culture into one that strives to this day to live in a sustainable equilibrium with nature. [Answer] Some cats are mostly vegetarian. Dried cat food is 70% grain. With a bit of meat flavouring they like it enough. Meat diets requires far more land per person than vegetarian. So resource limitations would put pressure to do more with less. A push factor. Any civilisation forms after they can generate food surpluses, freeing up labour for other things, like war, religion, building wagons. These are pull factors for eating vegetarian diets. And an event could precipitate the change, a volcano blocking the sun for a year, forced them to conserve food by adding plant matter. Afterwards, no one got hurt and it was cheaper. Poorer families kept eating veggies with their meat. [Answer] Well it's simple. Just because they only have pointy teeth does not mean they can't eat plants. Ask any pet owner. Some cats, and all dogs, will eat mostly anything that we can eat. Yet, officially, they are carnivores. In the wild, a decrease in the amount of available prey coupled with an abundance of plant food translates into evolutionary pressure towards onivorism, which if continued for long can lead to herbivorism. This has happened more times than we can count on Earth. Of special notice are birds: parrots, humming birds and toucans all share a common ancestor with all other birds, which is believed to have been a carnivore theropod. [Answer] The big problem for your elves is taurine, arginine, and various other nutrients that plants don't provide and they can't synthesize. Mutations might be possible to allow synthesis. Another possibility is that they turn herbivorous when they have a degree of intelligence. In particular, they can use fire. (Possibly not make it, but use it.) Cooking food increases the availability and ease of digestion of nutrients, thus allowing them to sustain a higher energy lifestyle on lower quality plant food. Perhaps as they grew more intelligent they devised ways to cook up the nutrients that they can't find naturally occurring in plants. [Answer] # You are What You Eat: I have a couple of ways I can see that wouldn't require radical biological changes for you species to become (on the surface) herbivores, but it may require some flexibility with definitions. * **Symbiosis**: Your species has co-evolved with small intestinal organisms, once a free-living creature but now an obligate symbiote. The host evolved a second stomach where these creatures now live. The hosts eat the food for the symbiote, and the symbiote has to do nothing to survive. They shed eggs which are everywhere in the host environment. The symbiotes either die or are pushed out into the second (true) stomach of the host and are digested. While the host is still capable of eating meat, it doesn't need to. * **Choice and selection**: The elves made an ethical decision to abandon flesh, but they are brilliant biologists. They cultured, engineered, and selected for plants high in protein (and complete protein at that) and easily digestible. Their trees produce fruits and nuts, their mushrooms are as rich as steak. These organisms require great care and maintenance, but provide everything they need. Who needs dead animal when your food is already like meat? * **They don't know it's animal (or it's technically a protist...)**: Everything the elves eat is cultured with an ameboid organism the elves spread to all their food. These tiny animal-like organisms eat all the fruit and vegetables, leading to either a nutritious liquid (call it nectar) or a dried flakey protein-filled residue (ambrosia?). They cook it, eat it raw, whatever. They spread it like sourdough. [Answer] We actually descend from similar species, since primates come from the Eutheria too <https://en.wikipedia.org/wiki/Eutheria> small carnivores/insectivores. [Research](https://www.sciencedaily.com/releases/2018/07/180711105725.htm#:%7E:text=2-,Eating%20bone%20marrow%20played%20a%20key%20role,evolution%20of%20the%20human%20hand&text=Summary%3A,like%20ours%2C%20research%20has%20found.) shows that our specie's brain developped thanks to hominids eating marrow and that that makes us omnivores, but that is not the only source of fat. You can find [all 3 fatty acids necessary](https://www.scientificamerican.com/article/by-land-or-by-sea-how-did-early-humans-access-key-brain-building-nutrients/) for humans (and fundamental in brain development) in plants too. So what you haveto do is put them in a bioma where the right kind of plants are more abondant than fish or mammals. ]
[Question] [ In my Fantasy/sci-fi universe there exists a lighter than air gas, that is non-flammable, while having density similar or even smaller than hydrogen (I will post some questions related to this gas in the future). This gas, combined with light and strong materials used in universe, permits making big airships that can lift big weight, but not making steampunk-looking flying battleships. The airships carry a light armor on crew areas, ammo storages etc, but the whole envelope is not armored, but divided into many gasbags, like airships in real life were, so piercing a few of them won't bring the airship down. To clarify, these airships are **rigid airships**, not blimps. Now, the question is: **what weapons are best for airship to airship combat in such scenario?** I was thinking about simple thermobaric warheads for tearing apart envelope and gasbags, coupled with light cannons for precise strikes on ship's vital areas, like engines, armament etc. What do you think? Edit: Some notes on tech level: military tech is similar to what we had on Earth post-ww1 but planes are significantly less advanced than in our world, they are similar to planes that took part in the beginning fights of First World War, and are sometimes used as deck planes for airships. Material tech is more advanced, and makes it possible to build durable drigibles. [Answer] You want to hit as many gas bags as you can, so something that spreads out once fired would be better than a single shot. **Grapeshot** would be like a cannon sized shotgun, making a large cloud of pellets. Like a shotgun, you have the disadvantage of having to be pretty close because each pellet doesn't weigh much and so will lose momentum and piercing power quicker than a large shell. [**Flechettes**](https://en.wikipedia.org/wiki/Flechette) are like small arrows, and can be bundled together to fire a lot all at once. This has some advantages over grapeshot in that they have more piercing power at a greater range due to their pointed tip and fletching to keep them straight. Being fired out of a cannon, you'd want to use heavier flechettes for increased range and accuracy. **Flak** is another useful anti-aircraft weapon that could be used with good effect. The main version uses a shell filled with high explosives and equipped with a fuse. The shell travels toward the target, then the fuse runs out which sets off the HE, and the shell explodes sending shrapnel in all directions. A blimp mounted system might use shells with different length fuses, depending on the range of the target. If a flak cannon has an effective range of 1000 meters, you might want the shell to go off at 500 meters, and so a gunner would want to have an assortment of shells to chose from. A skilled gunner might be able to get the shells to pierce the envelope, and then explode inside, which would cause a lot more damage. You could use an impact fuse, so that it explodes an instant after impacting the envelope, if there was enough of an impact to actually trigger the shell. Incendiaries could also be used to ignite the envelope fabric by filling a HE shell with phosphorus or other highly flammable substance. It wouldn't ignite the gas, but it could still burn the gas bags. [Answer] **Tactics** The most common weapon would be explosive or incendiary missiles - this would devastate your airship's armour and/or burn through it. These are the same missiles used today. These can be fired from any position, ground or air. However if you don't have missiles, you mentioned cannons. Again, explosive shells seem the best bet to disable an airship - because of weight airships can't have much armour. Remember you don't need to completely destroy it, only break it up a little to reduce it's altitude or become uncontrollable. This poses a few issues: 1. Airships are quite slow moving and inherently fragile 2. Cannons have limited range 3. The higher you are the further your range. Therefore, the first thing Airship captains will do is to increase altitude as much and fast as possible when in contact with an enemy target. If it is a battle between two airships, the highest airship wins. **Airship Design** Therefore airships have the best advantage the higher they are to begin with, meaning the less weight the better. That means less armour, as it doesn't really do much in a fight. Altitude wins the day and is your best defence (if there are no missiles...) [Answer] Firstly, there's already a lighter-than-air gas with similar lift properties to hydrogen. It's called helium. Despite the higher molar mass, it has virtually the same lift as hydrogen. As for airships taking each other out, you're probably looking at timed explosive ammunition. Airship envelopes are so delicate, that they're—paradoxically—actually quite resistant to damage from impact explosives: they don't provide enough resistance to set off the charges and are likely to have an explosive or incendiary shell or bullet go right through and out the other side. Something with a timer on it, however, could wreak havoc *if* you get the timing right. A shell going off inside an airship's envelope would shred a lot of ballonets or gas cells and would at least force the damaged airship out of a fight. A crash would be unlikely, as they would probably still have enough lift to land safely. TV Tropes actually has [a useful notes page](http://tvtropes.org/pmwiki/pmwiki.php/UsefulNotes/Airships) about airships that could be very...well...*useful* to you. [Answer] **Solvent** putting enough holes in gas bags made with ballistics in mind might actually be really hard. If you use something that can dissolve the cloth, it might penetrate much more effectively than ballistics. It's the difference between shooting bubble wrap with an arrow, and spraying it with acetone. [Answer] **Forced landing weapons.** 1. **Autonomous grapnel anchors**. These can be used for [naval boarding](https://en.wikipedia.org/wiki/Naval_boarding) operations which would be exciting in the air. In another use, after the grapnel engaged with the target the near side is fired into the ground and an automatic winch winches the captured airship down to where it is out of action - or the ground troops can get at it. 2. **Cold gun.** This is the opposite of Greek fire, because burning things has been done so much and burns hurt. The cold gun would spray something very cold (maybe a supercooled gas, but maybe just cold salt water\* for its high thermal mass). This would not damage the ship or personel but would cause the gas bags to shrink, decreasing lift. The ship would gradually fall out of the air, to be captured intact. For either method, captured air sailors would be released after each one successfully sang the national anthem of the victor, and like he really meant it, and in tune. And with the dance moves. \*there might still be small fish and shrimp in this cold salt water. [Answer] For a slightly unconventional but low-tech weapon, try using birds of prey. Hawks are quite trainable and have talons sharp enough to shred the outer fabric shell of the enemy airship (razor-edged claw caps can make them even more effective). A projectile weapon will - best case scenario - tear one hole on the way in and another on the way out. A trained hawk can continue to rip and tear into the enemy ship until you call them back. They aim themselves, so they can attack a moving enemy in any direction, aren't significantly affected by heavy crosswinds, and have an impressive range. They're capable of flight at [airline cruising altitudes](https://web.stanford.edu/group/stanfordbirds/text/essays/How_Fast.html), and will be significantly more maneuverable than a bulky airship. They're reusable, but they will eventually tire so lengthy, large-scale battles will require some planning ahead. [Answer] Anti aircraft weaponry is designed to produce large amounts of shrapnel to destroy control surfaces (degradation of structure and handling) and hopefully get pulled into the jet engine air intakes (degradation of propulsion) Even if your airships have light armour, it will behave in a predictable way allowing weapons systems to be designed to counter it. If you look into the development of fighters post WW1 through to the end of WW2 their gun sizes and capabilities changed over time to bigger caliber rounds, and armour piecing capabilities because the targets were continually evolving - self healing fuel tanks, pilot armour, increased structural strength ... What you need to imagine is what led up to the designs of your ships - if it is new technology they will have been designed around an existing older tech (hence we call these vehicles airships for example), or they will have been modified to resist the current weapon technology and function better (compare blimps - essentially a minor upgrade from hot air balloons to the hard bodied airships built by Count von Zeppellin for example), to at least over a 50/50 chance of not losing both crew and airship, or much higher if the owner/operators of the airships are not in a situation where the resources required to make them are in short supply [Answer] You'd definitely want some sort of [chain shot](https://en.wikipedia.org/wiki/Chain-shot) grapeshot and the like would be great for making lots of holes, but chain shot would make large tears that would quickly allow the buoyant gas to escape. I would expect combat to focus around getting above your opponent, as Flox describes. In addition to greater range, it would allow you to focus on the envelope of the enemy airship. If the weapons are only on the bottom, this would prevent lower airships from returning fire at all. Airships would evolve to be able to raise quickly, and have guns that can shoot downwards. They may also drop bombs on airships/ground targets below them. [Answer] Depending on tech-level: * Anti air missiles that use Shrapnel, such as [Hawk](https://en.wikipedia.org/wiki/MIM-23_Hawk) or [BUK](https://en.wikipedia.org/wiki/Buk_missile_system#Operation). Shoot one into the vicinity of an airship and watch most of it´s gasbags turned into rags. * Cannons, loaded with [grapeshot](https://en.wikipedia.org/wiki/Grapeshot). Same principle, but you have to make a fly-by short distance for it to be effective. [Answer] **Gas Weapons** Something not yet mentioned is gas, a weapon very fitting for the period. Getting poison gas into the enemy crew-cabin is game over. Even if gas masks are used, the massively reduced visibility is going to severely cripple enemy crew performance. If the same gas is also corrosive then it could potentially damage very large surface areas of the enemy gas bag, and as it condenses it could even drip down to damage the internal gas bags. Treating the gas bags to resist this kind of attack would have a huge opportunity cost in terms of weight. Finally, the gas would certainly be heavier than the gas used for lift. This means that any gas inside the enemy gas bag would displace a similar volume of vital lifting gas. [Answer] Thermobarics will certainly have their uses but in the interests of not having to totally destroying every target, [Chain-shot](https://en.wikipedia.org/wiki/Chain-shot) or something like a [Rivebow](http://baslag.wikia.com/wiki/Cactacae) that fires a cutting disc would be quite useful, you can aim at the fabric of the bag or the anchoring lines that attach it to the gondola with equal effect that way. [Answer] Flak cannon with a timed burst. Shred the internal gas chambers. Note that precision timed airbursts were a solved problem by World War One; shells could be set to detonate in the air above the target, on impact, or after impact, and that was due to timed fusing (proximity fuses only came around in World War Two). Firing at a (slowly) moving target from a (slowly) moving platform is more difficult than ground artillery firing at a fixed position, but again that's a largely solved problem because navies had been working on firing at moving targets from moving guns for a while. The third dimensional aspect (the target could be above or below your own altitude) adds a little more complication, but not much; snipers deal with that issue all the time. All it would require is slightly more math, and once you have the range it wouldn't take many hits to force an airship down. [Answer] **Fifty caliber Browning** machine guns. If those don't do it you need to invent the **Vulcan cannon**, post-haste. What's the thickness of the armor, it's composition, and what design strategy does it employ? Tell me what it is and I'll tell you what to shoot at it with. *I only need to know one thing...* --- In reality you should be putting all of your resources towards advancing flight, because whoever learns first that airplanes are 1000x less fickle than airships (and has the necessary resources to build them) will win the war. The US had the two coolest [aircraft carrying airships](https://en.wikipedia.org/wiki/Airborne_aircraft_carrier#USS_Akron_and_Macon) ever built, but they both crashed due to weather and killed a bunch of people. TL;DR: build a **weather machine**. If I were your adversary, **my weapon would be deception**. That being, I would appear to match your airship program tit-for-tat, plus a one-up, to make you keep dumping resources into your program. [Answer] ## Incendiary Cannons Essentially cannon shells filled with napalm. They'd have a small high-explosive charge to ignite and disperse the fuel, carefully delay-fused to explode inside the lifting cells. The goal isn't to set the gas alight, but to make it rapidly expand from the heat, bursting the lifting cells. The shells would have to be quite large to carry enough fuel, and so would have limited range. The shorter flight-times at close range would also make it easier for the delay-fuses to be adjusted correctly (it would have to be done manually). This means that our airships will first engage with intense, close-range broadsides. Eventually, one ship will lose critical lift and be forced to lower altitude. Once this happens, the higher airship can begin to back off, slipping out of the lower airship's range while continuing to fire on it from above. ## Gravity bombs Once the losing airship has been forced to the ground, it can be totally destroyed with conventional gravity bombs. ## Flak Cannons These are useful for degrading the firing capabilities of the enemy airship. As pointed out by others, they're not effective against the lifting cells, but they can be targeted at the gondola, where they can sever control lines, injure personnel, and destroy weapons and ammunition. ## Sniper Cannons This is something we don't really have an equivalent for in Earth-tech. Without the speed and maneuverability of heavier-than-air craft, we can expect extended aerial pursuits between airships, as one seeks to avoid or delay engaging the other at close range. These would look a lot like chases between old sailing ships, except that stability and altitude give the two vessels clear lines of sight to each other at all times. This opens up an opportunity for long-range, high-accuracy weaponry. Imagine something like a sniper rifle, but even higher caliber and velocity. Pivot-mounted to the deck, featuring an extremely long, rifled barrel, and relatively lightweight ammunition. Operated by a single, highly-trained crew-member, it would be fired at the propulsion engines of the enemy craft. Even a relatively small hole in the right spot could significantly slow an airship until repairs could be made, allowing the fleeing party to escape, or the pursuing party to catch its prey. ## Guided torpedoes A moderate range, heavier than air torpedo, featuring wings and a massive high-explosive payload could potentially destroy an airship with a single direct hit. In order to be practical, such a heavy and expensive weapon would need the most effective guidance system available to an interwar society: a human pilot willing to die for the cause. Desperate, but effective. [Answer] ## Lasers I’m going to (semi-)humorously suggest that lasers would be an *awesome* way to create holes in other airships. This is a low weight, long distance, perfectly accurate system that is dependent solely upon the amount of energy you have available to burn and the tech level available. Sadly, it wouldn’t work during storms, but do you really want to be in an airship during one of those anyway? This would also inspire some interesting airship design - likely with reflective/white balloons. ![enter image description here](https://out.reddit.com/t3_2racxf?url=http%3A%2F%2Fi.imgur.com%2FYSYDV4J.gif&token=AQAAsiXyWhwHGNYVuihmBA2gDgJHs_4uaahNUf3oUOm1OgIlLwZf&app_name=mweb2x) ]
[Question] [ I have a race in my world that in most respects is comparable to a human, perhaps not in form but certainly in function. One of the key differences between humans and this species is a **lack of opposable thumbs.** * This species still has five fingers. * The fifth, instead of being a thumb is essentially an extra pinky where the thumb would be, this changes the wrist bones and all that. * Their fingers are slightly longer and slightly stronger * Their manual dexterity is slightly lower than a human, meaning precision is a bit lower. As in the title I am particularly concerned with how this would impact the development of firearms. For the sake of this question assume all other aspects of using a firearm are functionally the same as a human. (aiming for example) **Firearm Requirements:** * Must be for personal use, meaning only one person needed * Include design considerations for both pistols and rifles (both single and burst/auto) * How will it be held * How will the trigger be situated * Ensure reload is effectively easy * The weapons should stay as similar to modern ballistic firearms as possible [Answer] ## There won't be any diagonal gun grips There are six main motions that the [human hand](http://www.oandplibrary.org/al/1955_02_022.asp) can make: * cylindrical grasp * tip grasp (between finger tip and thumb tip) * hook grip * palmar (between pad of finger and pad of thumb) * spherical grasp * lateral grasp (pad of thumb and side of pointer finger) [![Grip Types](https://i.stack.imgur.com/nYZSp.jpg)](https://i.stack.imgur.com/nYZSp.jpg) Of these six, only one can be done for sure without a thumb. The others are either impossible or very clumsy. Because the pistol grip typically used by humans on our firearms requires a thumb, that grip style won't work for these five-fingered-no-thumbs people. Since the cylindrical grip still maintains a great degree of power and control over the hook grasp, we'll design a firearm grip around that motion. Because they no longer have a thumb to brace against the recoil of the weapon, the recoil will need to go somewhere else. It can't go into the fingers because the grip is moving in the weakest direction for the fingers to grasp (ie, the grip is moving back towards the wrist, away from the fingers). The wrist and forearm seem the best place for me. If the barrel of the firearm is placed co-linear with the axis of the firearm, accuracy can be preserved as well as recoil force put into larger/stronger body structures. [![Something like this.](https://i.stack.imgur.com/VUH1j.png)](https://i.stack.imgur.com/VUH1j.png) I'm sure that some clever machinist is going to come up with a different, better, more efficient firearm than I just did. I don't see how you would use any other finger for the trigger other than the "thumb" or the pinky since all the other fingers would benefit from being squeezed together. There's plenty of space to innovate. This doesn't address in the least the problems with loading shells into the gun since humans use a pinch grip when loading rounds. These non-humans can only do pinching motions in a very clumsy way. I don't know how you could make reloading efficient given the inferior grips available to these creatures. Rifles could easily dispense with the forearm brace and use a shoulder butt much like normal human rifles do. The above (and very crude) diagram shows a possible pistol sized weapon. [Answer] Take a look at "old style" crossbows - trigger mechanism was a lever underneath the hand grip, simply squeeze. May be easier to do it with a thumb around the top of the stock, but with a longer palm having the heel on top and wrapping those longer fingers around should do just fine. For pistols check out the "squeeze action" Protector Palm Pistol - based on image not having a thumb shouldn't be an issue. Range and accuracy issues though... [![Medieval style crossbow w/ lever trigger](https://i.stack.imgur.com/t2PGm.jpg)](https://i.stack.imgur.com/t2PGm.jpg) [![Protector Palm Pistol](https://i.stack.imgur.com/3zghv.jpg)](https://i.stack.imgur.com/3zghv.jpg) [Answer] **When life gives you lemons...** ... in this case, don't make lemon grenades. Just make do and turn your fingers into thumbs. For example, try gripping some sort of handle with your two middle fingers on the front (as normal), but your index and pinky fingers on the back (so the backs of the fingers are touching the handle). It feels weird, but it should work. Now, imagine you've been holding things like that your whole life. The human body would have adapted to make this grip easier for you; this fictional species should have the same adaptability. Similarly, gloves are great at improving grip, so maybe this species has specialized gloves they can wear that make this kind of grip even easier. So I'm thinking you could make firearms pretty much the same as they do now. It seems like grips would have to be thinner, which means magazines will have to go in somewhere else (which they already do for most guns, I'm just saying pistols will look different). The trigger will have to be operated by the middle finger (gives a whole new meaning to flipping someone off). Other than that, I'm thinking things could stay the same. I know this is kind of avoiding the premise, but I think opposable thumbs are so useful, that something similar to them has to be one of the first inventions of an intelligent species. If they can't get them through evolution, then they can get them through practice. Anyway, here's a picture of what I'm describing: ![sketch of alien hands](https://i.stack.imgur.com/36X1p.jpg) [Answer] something like a suitcase gun handle might work, or like the guitar gun from desperado. Both are terrible for aiming though, but on the other hand bulk would be less of an issue. With this recoil would also be more of a problem on large guns, something more like a normal rifle would be good for larger guns. Shoulder bracing will make even human long guns work fine. the real issue is how do they build them without the ability to do precision grips. [![enter image description here](https://i.stack.imgur.com/nrwXJ.jpg)](https://i.stack.imgur.com/nrwXJ.jpg) [![enter image description here](https://i.stack.imgur.com/29R6S.png)](https://i.stack.imgur.com/29R6S.png) [Answer] # TDLR; Make it triggered by the shoulder, and loaded vertically from the front. [![enter image description here](https://i.stack.imgur.com/eWkSF.png)](https://i.stack.imgur.com/eWkSF.png) Using an electric mechanism on the shoulder, you avoid any typical trigger mechanism, and can use a basic electrical connection (similar to a flashlight), to trigger the firing pin. Other options may include mechanical firing mechanisms, but this may add weight to the weapon. Rotating the bullets by 90 degrees allow for a hand on the foregrip, and the other to be loading bullets, similar to a shotgun. If you're worried about accidental discharge, you can add a hand trigger (a grip with a button on it to make a similar electrical connection), and hold the weapon without it depressed. The advantages are continuous loading, allowing for a never ending stream of bullet, simply design, tactical/logistical ease, and universal usability (we could use this now if we wanted!). Downsides as mentioned are accidental discharge, sniping inaccuracy, and general gun maintenence. The stock would most likely be hollowed out to make room for firig mechanism, but would require extra weight to allow for possibly multiple buttons, and the mechanism would not be as conducive to sniping due to the movement involved. The mechanism itself would be difficult to clean on the go, and any gun maintenance in general is difficult without thumbs to make pinching motions. As for pistols, just add a stock ([a lot of pistols have stocks as well](http://www.recoilweb.com/usa-1shot-non-nfa-butt-stock-for-your-handgun-69131.html)). You could make it single shot and loaded directly onto the barrel, or expect that reloading would use multiple smaller magazines with a smaller barrel. [Answer] # Rat-like grip Rats have surprisingly dextrous hands despite lacking opposable thumbs (or really anything resembling a thumb). Rats can grip objects by pressing them between their palm and fingers, or more often with a two-handed grip. (You can see this two-handed grip most easily if you watch a rat eat something small.) Their guns would likely be designed to be gripped between two hands. Pulling a trigger just requires a free index finger. For reloading, you'd have the magazine designed to comfortably fit between the fingers and palm, and not require much dexterity to put in, because one-handed grip is far less dextrous than two-handed. You'd probably also design the gun to be braced against the body while reloading, so you can maintain a one-handed hold on the gun. ]
[Question] [ Imagine an Earth-like planet with oceans that are comprised roughly 50/50 of heavy water and normal water. My understanding is that while heavy water ice sinks in normal water, it would float on heavy water. But would it float completely below the surface in an ocean that is a mix of heavy and normal water, or would part of it be out of the water like a regular iceberg on Earth? I want to make sure there isn't any massive flaw in my understanding in whether such a thing (completely underwater icebergs) would be possible. **EDIT** Thanks everybody. To expand on what I'm thinking about, I'm imagining a planet that has one supercontinent in the north, and the rest of the planet covered in one big super-ocean, with land:water ratio being around 25:75; so an ocean far bigger than any currently on Earth. I gather from the comments that the big issue is that this ocean would eventually stratify into the different kinds of water. I think what I want to try and do is reverse engineer reasons why the ocean would stay stirred up, such tidal forces from a large orbiting moon, as well as biological processes (part of what I'm imagining for the ecosystem on this planet are lifeforms that photosynthesise with heavy water, so therefore dive down to fill up with D20 and then dive up to be nearer the sun). I'm less interested in there being super-stable conditions that allow the icebergs to glide at a fixed depth, in fact, the more chaotic the system the better. Would D2O icebergs be more likely to form if the planet received less energy from it's star? Or if the ocean had significantly less salt than our oceans? Again, thanks for all your comments! [Answer] ## Assuming a spherical cow in a vacuum. I mean a planet with 50/50 D/H instead of almost entirely H. Any given D or H atom is going to have a 50/50 chance of binding with either a D or an H atom. *What does this mean in practice?* It means that your oceans aren't D2O and H2O, they're a mix of D2O H2O and HDO (I believe a 25/25/50 bias towards the last, semiheavy water). It's that semiheavy water that's the confounding molecule. It's not normally interesting in itself, it's usually considered a raw material for making D2O, but in this case it'll be a solid proportion of your water and needs to be accounted for. In terms of your calculations, you now have three weights of water and three of ice, ignoring the mixtures. Now there's the question of freezing the water. If the oceans aren't mixed then only H2O will sit at the surface so only H2O will freeze and stay floating, the other waters lie deeper below the freezing layer. If the oceans are mixed then the water will freeze as a mixture and you end up without the fun effects anyway. *Sorry.* Apparently people spend their lives studying this: [Chapter 3 in this book](https://books.google.co.uk/books?id=Ez26jkzTauoC&printsec=frontcover&dq=Ferronsky+polyakov&hl=nl&sa=X&ei=76UNUObrMe6k0AXR_-m6Cg#v=onepage&q=Ferronsky%20polyakov&f=false) for example. [Also XKCD forum](http://forums.xkcd.com/viewtopic.php?f=18&t=87613). Both found via our own [Physics.SE](https://physics.stackexchange.com/questions/69930/deuterium-density-in-seawater). I think we can reliably say the water is evenly mixed. This is before considering the oxygen isotopes, you could make some *very* heavy water. [Answer] It's all a question of densities. Since the heavy water is about 11% denser than normal water the 2 will naturally separate in a static ocean. Obviously the ocean is not static, there is up and down movement of water due to temperature, but the difference between cold water (0C) and hot water (40C) is less than 1 percent so any currents will occur in the top half of the ocean where the normal water is and the heavy water will not be affected. [![enter image description here](https://i.stack.imgur.com/OUwAj.png)](https://i.stack.imgur.com/OUwAj.png) Even with the effects of wind and tide, over billions of years, the two will separate completely. If the heavy water is deep below the surface of the ocean it won't freeze. Here is a picture of the temperature of the ocean at different depths [![enter image description here](https://i.stack.imgur.com/pfQrU.jpg)](https://i.stack.imgur.com/pfQrU.jpg) As you can see even at 4500m the temperature is around 4C which is right near the freezing point for heavy water, but since oceans are salty, the freezing temperature for ocean heavy water will be lower. All in all, it's not possible. Which is probably a good thing because heavy water has negative effects on plants and animals (at least on Earth, you might be able to make a case for life adapting to it on another planet). Even if you could form ice that's denser than the water around it, it would simply sink to the bottom of the ocean (or until it reaches the heavy water portion). The water density changes very little with depth, mostly due to changes in temperature and salinity. We are talking less than 1%, so heavy water ice will simply sink in normal water. Here is a cool experiment showing just that: <http://mathscinotes.com/2014/02/heavy-water-ice-cubes-do-not-float/> [Answer] Unfortunately...the mass/buoyancy differences between Heavy water and Normal water are negligible when compared to the forces of convection, currents, wind/wave/biological agitation, thermoclines, gas release from the ocean floor, Brownian motion, and all of the many, many other forces out there that are stirring up the ocean. You aren't going to get nice, tidy layers of water...there's too much stirring going on. More likely, you'd end up with icebergs that simply sat lower in the water than normal, with a few rare occasions where you might get one that was mostly submerged. The reason behind this is that Heavy Water has a higher freezing temperature by 3.82 degrees celsius (6.9 degrees F). Therefore, when water started to freeze, the Heavy Water would freeze first, followed by the normal water. And conversely, when an iceberg started to melt, the normal water would melt first, followed by the heavy water. So, in general, an iceberg formed by freezing ocean water would be made of more heavy water than normal water, and would thus sit lower in the roughly 50/50 mixture that was the ocean (slightly different from that, because more of the heavy water that was present at the time froze.) Exactly how deep in the water said iceberg would sit is mostly dependent on how quickly it formed, and how it formed in the first place. One way in which icebergs form is by breaking off from glaciers, which are built up atop mountains via precipitation. These icebergs would start off with a slightly higher percentage of normal water, because normal water (having a slightly lower boiling point) evaporates more readily than heavy water...though not by very much. The other way icebergs form is by direct freezing of ocean water, which then breaks up as it starts to thaw. These would form with a higher percentage of heavy water, because heavy water freezes faster than normal water. Ultimately, the problem is that the 3.82 degrees C difference is too small. If you could hold the temperature right at 2 degrees Celsius for a long time, you could form icebergs of almost pure heavy water (which would sink in the 50/50 mix of the ocean...they wouldn't reach an equilibrium point where the Heavy Water concentration was higher and they'd start to float). However, daily temperatures tend to swing more than 3.82 degrees C, so you're pretty unlikely to see these optimal conditions. (Also possibly worth mentioning....50% deuteration in life-as-we-know-it is fatal to anything more complicated than bacteria) So, TL;DR: Your ocean would be a pretty consistent mixture of half and half H2O/D2O, and the chemical differences between the two are narrow enough that most icebergs would end up sitting a little lower or higher in the water (depending on how they formed), but would not magically float halfway down the depths of the ocean. There are too many forces at work keeping the ocean nicely stirred up. [Answer] So what I'm getting out of your question is the following scenario: We've got a large body of water, like a lake or an ocean, that contains both H20 and D20. There are some H20 icebergs and D20 icebergs in the water and you're wondering if/where they will float. Gotta say, this is a pretty cool question! Now let's do some science :D First we need to decide if the icebergs are 100% one type of ice, or can they be mixed like 30% H20 ice and 70% D20 ice? Let's start simple with pure ices. Now how about our body of water? Is it agitated at all? Sufficiently large bodies of water tend to be large enough to experience winds across their surfaces, making waves. This agitates the water and mixes it up, but maybe not enough to get the H20 and D20 to mix will. After all, when you swim deeply even in fairly wind-agitated water, it's still easy to feel a [thermocline](https://en.wikipedia.org/wiki/Thermocline) about 13 feet down in most lakes. So again, we'll apply Occam's Razor to our thought experiment and go with a perfectly still body of water, at exactly 50% each H20 and D20, split right across the middle. Now we get to the icebergs and the water interacting! With this impossibly simplified set-up, you're correct in assuming the D20 bergs will "float" on the D20 water around halfway deep in the lake, and the H20 bergs will sit near the surface as you'd expect any iceberg to. If the bergs are mixed ice, they would sit somewhere between halfway into the lake and on the surface depending on their composition, more D20 being closer to the middle depth of the lake. If our lake is agitated and mixing, then things get REALLY cool as we essentially have dynamic buoyancy for each berg depending on the water column its in. There's probably some crazy math to show how that would change over time, and would probably be a pretty cool simulation, but that's just a biiiit out of the scope of what we're doing here. Hope this helped, be sure to let me know if it did! [Answer] Are you sure the heavy water would separate? Our ocean has pretty powerful pumping mechanisms to get surface water to the depths and vice versa. e.g. cold saline water sinks at the poles as sea ice forms, then flows along the ocean floor all the way to the equator (or beyond). Google the [global ocean conveyor belt](http://oceanservice.noaa.gov/facts/conveyor.html) or [thermohaline circulation.](http://oceanservice.noaa.gov/education/kits/currents/06conveyor2.html) As as aside, at the times in Earth's geological history when we had no ice caps, everything bigger than a bacteria in the deep oceans **died** because there was no oxygenated water being pumped down there (so oxygen would decline with depth, way beyond the modern oxygen minimum layer of 1000m). So if the heavy water does become a separate layer, nutrients are just going to sink or be osmosis-ed (omosed?) into it and vanish from the various biological cycles. ]
[Question] [ Monsters are creatures infused with (and mutated by) Chaos Energy, which both grants them "magic" and a sixth sense called, appropriately enough, [Chaos Sense.](https://worldbuilding.stackexchange.com/questions/213594/impact-of-chaos-sense) However, magic in my world functions on two principles: **balance** and **flow.** Balance causes magic to diffuse from areas of high to low concentration, thereby spreading the influence of Elemental energy out instead of concentrating it in one place. The Principle of **Flow,** however, limits spreading, as magic is attracted to magic of the same type as itself. In other words, Fire Magic is drawn to Fire Magic. The end result is something like spilling water on a table; give it time, and the water will stop spreading, forming one aqueous blob on your tabletop. Magic spreads to fill the space around it, but it doesn't move too far from its source. Makes sense, right? **However, this also has some pretty big ramifications for monsters:** **1. Flow:** Thanks to the Principle of Flow, monsters are attracted to monsters of the same Element as they are (firesnakes are drawn to fire dragons, for example), but more especially to *their own kind.* This may not seem a big deal, but here's the thing: since magic attracts magic, monsters have an overwhelming preference for preying on other monsters. **2. Balance:** Just as hot objects radiate heat, magical creatures radiate magic, causing a more or less uniform spread of magic in an area. **3. Synergy:** This is yet another Principle of Magic, and how it works is simple: magic bolsters and enhances magic of its own kind. **If this doesn't make sense, here's an example, a metaphor:** We have a Pyromancer, Alice. In the AU, she's a bowl of chocolate ice cream. Alice=Fire Mage=Chocolate Ice Cream. Alice meets a Giant Firesnake and, being a snake fan, she lets it coil around her. It's magic synergizes with her own, increasing both their power. Firesnake=Chocolate Syrup. Chocolate Syrup+Chocolate Ice Cream=2x the chocolatey goodness. **Just like chocolate syrup makes chocolate ice cream better than it could be alone (and vice versa), the firesnake's fiery aura makes Alice the Pyromancer stronger than she'd be on her own.** **Because of this,** monsters find they get a boost (not just an energy boost, their speed, power, and durability are increased as well) from hanging around monsters of the same element, which is why firesnakes hang around fire dragons. This boost is especially strong between members of the same species, which is why monsters tend to be found in groups, if not in pairs, and are generally not alone. Exceptions are boss monsters, or any large and powerful monsters, as their magical and biological needs necessitate they keep their territory all to themselves and fight off other members of their kind. **Anyway,** if a monster was to kill and/or eat their own kind, or to eat their own kind's Drops, they'd gain this boost from the Remnants or lingering essence of their species, and this boost stacks. **This would seem to encourage cannibalism, if not interspecies combat, so why are monsters not known for either?** [Answer] ## There are plenty of reasons why monsters should not eat their own kind In our natural world it is actually quite common for a species to 'eat' their own kind. In fact, it is theorised up to 1500 aquatic species do participate in it - and many in the insect world and animal kingdom. However, cannibalism generally occurs in resource depleted, or food scarce areas, and also that still leaves many species that do not do this - and for a variety of good reasons: * Over time, the survival rate of populations that eat their own, or even similar related species **decrease in population as external food sources are replaced by more easily found local ones** (for instance your easily found siblings or children) * There is an **increased risk of pathogen transmission** through eating animals of same or similar kind, including fatal or debilitating parasites * Significant resources (both genetic and environmental) are expended by species in defence against their own kind, **reducing the available resources for foraging or defence of other ostensibly more vital external threats** * Eating your own kind is actually not nutritious beyond immediate consumption - **you may need nutrients that are not found in your meal** and your prey may have only found them in others of its own kind. This means there are little or no external nutrients that may be needed injected into the system, and may cause developmental defects over time in particular if there are no immediately available alternative food sources * It has been shown that many **species that do have cannibalism are solitary**, and communal or social species tend not to have these traits. For instance, spiders often are cannibalistic with females often eating male spiders, however males do not really perform any further role and often are in fact willingly consumed. However, females tend to be much larger, and able to exist on their own. * Eating your own kind for your benefit also reduces your capacity to recognise your own children. Many species have been observed to 'accidentally' eat, or fail to recognise in time, their own children or eggs and **unwittingly eat themselves out of their own gene pool**. All of these principles can transfer quite readily to your Chaos Energy, as this is really a similar function to that of nutrients. [Answer] # Wrong logic: Strictly speaking, human is the best food for people to eat. It's perfect balanced nutrition, with the ideal mix of nutrients. Yet people rarely eat each other. Your creatures could have instinctive revulsion to this behavior, because synergy is way more beneficial than a quick temporary boost from chowing down on another creature of your same kind. Intellectual monsters will recognize having another fire creature around contributes to sustained success. So just as people get more from social behavior with other people than from eating them, monsters get more sustained benefit from symbiosis and society. [Answer] **You don't hunt something the same size as you** Preying on your own species guarantees a relatively even fight, which is far too dangerous. Even if there is a clear favourite to win, they will be close enough in size and capability that they could cause serious injury. Any injury in the wild is a potential death sentence from infection, starvation or from not being able to escape predators. Animals of the same species do fight over territory or mating, but this is not an all-out, to-the-death scrap because that would be far too risky. When animals want to eat other animals, they pick prey that they can subdue with the least risk. As long as your magical creatures have an instinct to self preservation, they'll play it smart and avoid cannibalism. [Answer] **Different flavors of magic!** In life, the life force of your creatures (and humans) reinforces their native magic flavor, suppressing the rest and especially suppressing the opposite type of magic. In death with the disappearance of life force, the dominant magic in any drops or remnants is the inverse of what the creature had in life - the photonegative. The magic left over from dead things weakens the kind of magic that thing had in life, which is why the life force suppressed it. The drops and remnants from a thing are anathema to creatures of like type to that thing. The magic remnants will contaminate and weaken them. Other things could be interested - things whose dominant magic life is aligned with this inversed magic produced on death. Those things will be attracted to creatures that are their opposites in life. That will be a hard fight for both, given that their magic types will be polar opposites. [Answer] # The deciding factor is how much bigger the consumption boost is from the companionship boost. Let's say in a hypothetical example that 5 well equipped adventurers will be attacked by chompers. We have 2 scenarios: one in which 10 chompers attack the party and one where a single chomper that ate the other 9 attacks the party. For the sake of simplicity, I'll say that here the boost doubles strength and shell thickness temporarily, but the boost is permanent if you eat the others. On scenario 2, the chomper has a shell 512 times as thick as that of a normal one, and is 512 times stronger. And now off it goes to face the party. Let's assume each party member takes T seconds to take down a single normal chomper, but when they get to act together and gang up on a creature, that time is divided by 4. For simplicity, let's say that if the chomper's strength and durability doubles, the average time is multiplied by 1.5 times the mustiplier (aka if it takes T seconds to kill a normal chomper, a chomper with a shell 4 times thicker and 4 times stronger takes 6T seconds to be killed). So essentially, each party member alone would take T times 1.5 times 512 equals 768T seconds to take down the super chomper, but since it's a single chomper the party can gang up on, that time is divided by 4, meaning the party needs a total of 192T seconds to take it down. Now let's say they instead face the 10 chompers, with each party member facing 2 chompers at once. As far as I understand, the boost is bigger the more individuals there are, but I'll say, here that the boost is approximately half of what it'd be if they just ate the others. That means that in the second case the chompers are only 256 times stronger, but since there's twice as many chompers as there are party members, they can't gang up. Now each party member takes 384T seconds to take down each of all of the chompers, meaning they take a total of about 728T seconds unless I got something wrong and assuming that facing more than a single chompers doesn't take more time than it'd take to just take them down individually one after another. According to the calculations, we can easily see a potential reason the boost wouldn't make it worth eating your companions: the boost you get from eating your companions would help you survive individually, but it's worse than the boost you'd get from sticking together and playing the numbers game. if you only care about your survival, it's worth it, but if you care about the group's success it's not. If the boosts are cumulative, but the boost of eating only makes you twice as strong. Meanwhile, sticking together not only means you don't have to risk your life killing all of your companions, it also means you're more likely to succeed as a group, because while you're only half as strong, you're 10 times as many. Sure, this scenario is simplified, ignores some factors and makes the boost of companionship for the group half of the consumption boost you'd get, but it explains my point well enough: **Whether it's more advantageous to form a larger group than it is going rogue and eating any other monster of your kind depends on how much bigger the boost you get from eating your group is than the boost you get from sticking around**. If the final boost is not big enough to justify sacrificing the boost of companionship and the numerical advantage, then you're better off cooperating instead of risking your life by turning your would-be "friends" into threats. [Answer] **Q: doesn't magic fade out when the holder dies ?** Opening: *"Anyway, if a monster was to kill and/or eat their own kind, or to eat their own kind's Drops, they'd gain this boost from the Remnants or lingering essence of their species, and this boost stacks. This would seem to encourage cannibalism, if not interspecies combat, so why are monsters not known for either?"* How would the magic be transferred ? With the fire snake intimously coiled around the pyromancer in friendship and cooperation, it seems logical the two magicians merge. With one magician preying on the other, or killing the other, why would magic of the victim be preserved in any way ? It died, the magic evaporated and gets blown elsewhere, with the wind. **It's an inappropriate pattern for "magic monsters"** When you involve magic in a story, there's also a certain freedom arising from that. The author can use magic to bend the scenario in a certain direction. Existing stories featuring "monsters" follow certain patterns. Generally, "monsters" don't kill each other, they kill humans, we are their victims. That is what monsters do. Killing or preying on each other would be pointless, because monsters are supposed to threaten civilization, that is: the viewer, the reader, or the gamer. **When monsters fight, the winner is the good guy** When they are *different* species, monsters killing monsters is a popular topic. The bad guy is clearly distinguished from the good guy, by assigning human-like properties to the good guy. This effect was used in the iconic *Godzilla and King Kong*. They fight, the really dangerous one got killed. [![enter image description here](https://i.stack.imgur.com/UK2Z1.png)](https://i.stack.imgur.com/UK2Z1.png) In Jurassic Park III, the Spinosaur is killed by the Mosasaur, because the Mosasaur's artist behaviour resembles mammal species we all fancy. [![enter image description here](https://i.stack.imgur.com/L7pTv.png)](https://i.stack.imgur.com/L7pTv.png) [Answer] ## Risk versus reward. There are many species that will prey upon their young however outside of perhaps insects I am not aware of any that regularly prey upon adult or even semi adult members of their own species. (Except perhaps in times of extreme hardship/scarcity like droughts etc when driven to do so by desperation.) For that matter most large predators avoid hunting other large predators for food on a regular basis. Think lions hunting leopards for example. Yes lions will stalk and kill leopards occasionally if they can catch them without too much effort but that's because they view them as potential threats and competitors. They don't hunt them for food. The reason for this is simple. If you are a dangerous predator then hunting other members of your own species (or other highly dangerous species) is by default also dangerous. Predators instinctively do a risk and reward calculation. There's the amount of energy required to catch and kill the prey and the likelihood of being injured while doing so versus the amount of nutrition gained. So lions don't hunt mice because the effort involved exceeds what they'd get back in food even if there's zero risk of injury. And they don't hunt leopards or other lions for the same reason. Yes, they would get a lot of food if they succeeded but at the same time there' also high risk of injury and a lot of effort/hard work involved. And if you are seriously injured? Your dead. Badly injured animals (or monsters) won't survive long in the wild. They are now 'weak' and by default the risk calculation has reversed so they are now on the menu. So lions pick prey species that provide the most food for the least risk - antelope etc and so will your monsters. The only exception to this rule are *juvenile* members of the same or similar species. Lots of animals will catch and eat the juvenile members of their species, particularly aquatic animals. But again that's because the effort required is less than the risk/reward. In this case big can eat little without to much effort/risk. And is some species like crocs self predation is part of the thinning out process because once your large *nothing* preys on you. [Answer] I take that they are somewhat sophisticated mentally. In this case, they should be able to understand that they are better off collectively if their collective behaviour is towards surviving, as a function of individually not obeying the continual (but minor) urge to kill each other. [Answer] **Tigers don't eat other tigers.** Small aggressive dogs can scare off much larger more gentle dogs. [![enter image description here](https://i.stack.imgur.com/30Lza.jpg)](https://i.stack.imgur.com/30Lza.jpg) [![enter image description here](https://i.stack.imgur.com/B9gkl.jpg)](https://i.stack.imgur.com/B9gkl.jpg) [![enter image description here](https://i.stack.imgur.com/F0wRj.png)](https://i.stack.imgur.com/F0wRj.png) This is because animals respond to confidence. Predatory animals stake out a territory where they hunt. They keep out their neighbors of the same species, but prefer to drive intruders away rather then kill them. There are several reasons this behaviour is beneficial. 1. Same species violence is very dangerous for both individuals. Predators tend to hunt things that are smaller than them, or pose them little danger. The same species fight is much more *fair*. $ \ \ \ $ 1.5 Remember ANY open wound can become infected and kill the victor as well as the loser. In nature animals prefer to intimidate or chase each other off than come to blows. 2. The neighbors are your children or siblings. Genetically you don't want to kill something that shares your genes. 3. The neighbors are potential mates during the breeding season, when the territorial behaviour is temporarily suspended. 4. The weaker neighbor is weaker than you because they are carrying a contagious infection. Stay away! The above doesn't change if you give the tigers superpowers. Even if a lvl 50 tiger is 100 times stronger than a lvl 20 tiger, they are not genetically programmed to understand this. They still respond to confidence and don't realise they are now five times the size they were at lvl 1. [Answer] Any large animal can be considered to be some sort of "monster" in the real world. For example, in the eastern USA there are small songbirds and squirrels everywhere that isn't very urban. And when I get within a certain distance they run or fly away from me because I, a human, are a giant monster to them. In prehistoric eras, the largest land monsters were sauropod dinosaurs. As far as I know they didn't fight each other much, and being herbivores they rarely deliberately ate meat. Thus it would have been extremely rare for sauopod dinosaurs to prey on and eat other sauropod dinosurs. Of course there were many species of carniverous dinosaurs that preyed on dinosaurs of other species. If think that tyrannosaurs often fought other tyrannosaurs. And if they killed other tyrannosaurs they might have eaten them instead of letting the meat be wasted by being eaten by other critters. In the present time, the largest monsters on land are herbivores like elephants, rhinos, hippos, buffalos, etc. And sometimes they might fight and even kill members of their own species, but being herbivores they would rarely eat any parts of their victims. And most of the largest and most monster like carnivores on land at the present might sometimes fight and kill members of their own species. And maybe sometimes they might eat dead members of their species, but I don't think that preying on other members of their species would be regular. And there are hundreds of living species of large enough to be considered "monsters" on Earth. And each species has its own lifestyle, and you would have to study all their lifestyles to see how large the percentage of species that could be said to prey on thei rown species is. It is my impression that only a small percentage of "monster" species actually prey on members of their own species. So possibly the real world reasons why it is rare for real "monsters" to prey on members of their own species also apply to your magical "monsters". [Answer] There are many similar symbiotic relationships seen in nature. Remoras are fish that attach themselves to other, bigger fish, getting protection while helping their "host", by cleaning them of parasites and bacteria. Sharks have been observed slowing down and allowing remoras to attach themselves, while some shark species simply hunt and consume them. Monsters could eat another monster, and gain a temporary boost in their power, more than what their otherwise symbiotic relationship would offer. But over time, it sickens them, it corrupts their own inner magic and as such, they become less powerfull than they would have been, had they not consumed their pet fire goldfish. A sort of magical loan, you need the extra bucks right now, but end up paying a little more back than you initially received. The effect could be more or less permanent, at the builder's discression. This would also give you ample opportunity plot-wise, you could try and trick a big, mean dragon that a big threat is coming, he eats his fellow snakes, but the attack was a ruse and all that burst of power wasted. A week later, he starts feeling bad from his fire gastritis, and that's when the water nation strikes. ]
[Question] [ How and with what would fairies build their houses? They need them because of the ridiculous number and variety of predators targeting them and the unforgiving weather. However, I don’t know with what they would build them, and how anything that they build would hold up. Their houses need to have roofs and possibly doors. There is very little magic in my world, and the weak magic that fairies have access to couldn’t help them. I have multiple different strains of fairies (one lives in a desert, one in a forest, one underground in caves, and one underwater), however the only strains I’m worried about are desert and forest. Desert fairies are (on average) 2 1/2 inches tall and forest fairies are (on average) 4 inches tall. My fairies have very poor memory, but other than that, their intelligence is very close to a human’s. Their tech level is very primitive except for a few that live in human towns and cities. They’re omnivorous and their predators are basically anything that’ll eat mice and/or bugs. They are very weak and have the endurance of a hummingbird. They are also diurnal. They can fly, however not for very long, but they can fly pretty high. They can also hover. I should probably also mention the weather... the climate is *very* cold, so their nests/houses need insulation, and lots of it. It also rains often, and it’s pretty windy, too. [Answer] **Mud.** [![mud dauber nest](https://i.stack.imgur.com/xXci7.jpg)](https://i.stack.imgur.com/xXci7.jpg) <http://entnemdept.ufl.edu/creatures/MISC/WASPS/Sceliphron_caementarium.htm> Mud is a fine building material. It is available everywhere. Depicted - elegant mud dauber wasp nests. If wasps can build this so can your fairies. Some wasps bring dry vegetation into their nests. They don't eat it, so maybe it is for insulation? That would work for fairies in cold climates also - line the mud nest with grass, fluff and scavenged fur. Mud is a fine building material for human dwellings too. [![mud huts](https://i.stack.imgur.com/rsWhi.png)](https://i.stack.imgur.com/rsWhi.png) <https://www.designcauseinc.org/single-post/2016/05/31/Construction-and-Cultural-Significance-of-Mud-Huts-1> [Answer] Anything involving the use of fire becomes intrinsically harder for smaller animals because small fires burn out faster than big ones, and small kilns dissipate heat faster and can't get as hot. This makes the production of many primitive materials like bricks, quicklime cement, and metal tools far harder for your fairies to achieve even if they were just as smart as humans. Likewise, a small home made from thin walls will heat up/cool down much faster than a human scale home which would be a problem, especially for your desert fairies. You also need to consider that many of their predators are much bigger and stronger compared to them than human predators are to us. So a house made from twigs or tiny stacked rocks could just be torn apart by a large bird, raccoon, etc. So, to have a home that is strong enough to resist giant predators and insulated enough to resist weather, and simple enough for tiny primitive humanoids to build, your best option would be burrowing into something rather than building it from scratch. Since your fairies can fly, burrowing into something up high would be best to prevent ground predators from getting you. This could involve hollowing out a tree or cactus kind of like a woodpecker nest, or if you find a nice steep flat cliffside, that could be even better since it would keep certain tree climbing predators like snakes out too. Something like an old human quarry, coastal cliffs, or canyon wall would be ideal. Humans have designed communities that are already a lot like this, in your case you just do it smaller and without any need for direct ground access. [![enter image description here](https://i.stack.imgur.com/g8yOQ.jpg)](https://i.stack.imgur.com/g8yOQ.jpg) [Answer] Despite not being very strong, the intelligence of your fairies should allow them to "punch above their weight" when it comes to other animals, utilizing superior tactics, tools, and strategy like humans do. With the capability to kill larger creatures, fairies could take over prepared homes from other species. For example: * Kill a [cavity-nesting](https://www.thespruce.com/description-of-cavity-nesting-385193) bird like a woodpecker or an owl and take over their home (trees, cacti, etc) * Kill a burrowing creature like a rabbit or groundhog and take over their home (already well-protected) * Kill a swarm of hive-building insects like wasps and take over their home (Use hive building material) Alternatively, your fairies could attempt to reach symbiosis with another creature or domesticate the creature * A fairy might provide a service to insect hives and be allowed to live in a beehive (where it's warm and there's food) * A fairy might live on a large mammal like a bear, providing a service in exchange for it's protection and body heat/fur in the cold * A fairy might live with humans performing tasks that require fine dexterity in exchange for shelter/food/etc [Answer] **Woven Nests** I'm going to put this answer here mostly because I like the way they look. We can look to the weaver bird for inspiration. [![](https://i.stack.imgur.com/V1ZKX.png)](https://i.stack.imgur.com/V1ZKX.png) [![enter image description here](https://i.stack.imgur.com/aOBCE.png)](https://i.stack.imgur.com/aOBCE.png) It could be built up like a bird's nest with their tiny dexterous hands. with some added fluff, I imagine it could be quite cozy. If you need more of a roof over your head, you can add some mud or layered leaves to shed rain. A small opening would make it easy to defend. And you could link these little pods together and have a much larger communal nest, where combined body heat would help keep things warm. Certain types of communal weaver bird colonies can cover a most of a tree, looking like a mass of nest material hanging from the limbs dotted with hole openings. [Answer] Well if the fairies have almost human intelligence, then perhaps they could build something out of baked clay or use something similar to clay and use it as a cement of sorts? [Answer] Dragongeek spoke about them killing or domesticating some animal that already build nests. You can google for a bird called "hornero" that builds spherical mud houses. It's found in South America. Maybe your fairies can occupy those houses, domesticate the birds or replicate the building method... [![This is the bird and its house](https://i.stack.imgur.com/SSvsU.jpg)](https://i.stack.imgur.com/SSvsU.jpg) [Answer] The faeries don't build houses, they steal the houses of other animals (nest, burrows, hollowed out trees, etc). But perhaps instead of killing the local wildlife to inhabit their homes the fairies could domesticate them instead. Birds would be most optimal for this since their homes tend to be higher up, where the fairies can reach on their own, and further away from predators. They have no need to build their homes because they'll have other creatures building them for them instead. It's up to you whether the fairy completely take over and either kill the birds or simply inhabit the homes and ignore the birds. But if the intelligence level of the fairies isn't high enough, or they have no upper hand in order to coheres, control or kill these creatures, then they could work together with some creatures in more of a symbiotic relationship in which they are the subjugated ones. The strange relationship between a certain species of spiders and frogs come to mind with this, specifically the Microhylid frog and certain species of Tarantula (I can't find the specific species for this, there are also other species that are seen in these relationships that I haven't added here). [![enter image description here](https://i.stack.imgur.com/VUB7F.jpg)](https://i.stack.imgur.com/VUB7F.jpg) It should be noted that these young spiders have been observed grabbing these frogs before releasing them still alive presumably because they didn't like how they tasted. These frogs may have certain toxins on their skin that make them poisonous or perhaps just distasteful to the large spiders and perhaps makes their certain relationship possible in the first place (this is speculation, not proven just observed). The frog would benefit living in close proximity by eating the small invertebrates that are attracted by the spider's left over prey while simultaneously receiving protection from large predators while the spider would essentially gain a live in maid. It has also been speculated that the frog would eat the ants that could potentially harm the spider's eggs that the spiders find difficult to deal with. However, these relationships are only seen rarely within nature and have only really been observed in Peru and India. But it should be noted that these are seen in unconnected lineages meaning these relationships are occurring naturally at the discretion of the spiders. This is just an example of a mutually benefiting relationship between two species in the wild. I'm not suggesting the faeries do the same with big spiders. You didn't mention what the fairies eat, but assumedly they could act as pest control to these creatures (whether it be birds, or hedgehogs, or whatever you decide) or the creatures themselves could feed the faeries as needed. It would be a bit like a janky roommate situation, only it would be up to you whether the fairies are active contributors to the household or are freeloaders that occasionally wash the dishes, so to speak. [Answer] Wood, built into or onto trees. Or burrow under a bush. Look at shelter constructed by small flying creatures, faeries could do anything they do. Faeries could even make little bricks, or mortar together stones. [Answer] ## Your fairies are basically like humans, just very small (and can fly) All the same issues that affect how we design and build our structures would be encountered with the fairies, with very similar solutions. A small sample would be: * Wet weather - your structures need to withstand rain and keep you dry, especially if you are small * The cold - your structures need to be insulated, and you need to keep your buildings warm artificially if naturally unable to * Economy - your buildings need to be made of materials that are available, arranged to suit the fairy economy and value system, and encounter issues of longevity, sustainability, cost-effectiveness and utility So, basically their structures would not differ from ours. If material science is relatively equivalent, timber is the easiest and most cost-effective material that accomplishes protection from wet weather, and is cheap. However, it has no insulative value, and little longevity. These issues may lead to the use of stone in conjunction with timber, with insulation through air gaps and sheep's wool. The development of better materials would lead the fairy society to progress to advanced industry eventually. Just a note: your fairy structures would differ from ours with respect to their ability to fly though. So, with this ability, you may be able to: * Have entries that are high up, so cities do not need to hug the ground (but they still need to be supported) * Have taller ceilings, and no need for interior stairs * Rooms could be stacked more, so buildings do not need to be wide if not needed * Cities could be vertically distributed, not just horizontally. This means workplaces could be in much closer relationship to homes, meaning infrastructure does not need to be stretched as many of our cities become when they grow. [Answer] # Leather Your fairies are weak against many predators, but they are the terror of any large beast with eyes and a need to close them some nights. (Such as a luckless human expedition to harvest fairies for muti meat, once they grow dispirited and careless) Swooping with sharpened javelins from above, the fairies leave their prey blinded, helpless, and at grave risk of infection. They need merely wait for nature to take its course, then start the brain tanning process. As thick as a fairy's hand, the leather is a tough, resilient building material that can be readily be attached at hard to reach places comparable to the woven bird nests discussed in another answer. With fine cordage of hair or sinew, it can be latched closed like a door. Nomadic cultures have achieved great insulating quality with leather in multiple layers with dead air between them. For the bolder fairies, free heat and transportation might be achieved by handing their leather house from the neck of a yak or musk-ox; they can then entertain themselves conniving ways to try to direct their chosen beast. [Answer] Your Fey people though not endowed with strong magic do wield a modicum of magical power. One of these is a modest ability to manipulate materials on a nanoscale. This ability is most prevalent in the construction of their dwellings. Where Desert Fey will separate individual sand grains to select the perfect type of crystals to bind to one another essentially growing their own crystalline houses on top and beneath the sands. Constructing strong walls and even using perfectly clear quartz crystals to channel sunlight, through long tubes, deep below the surface away from the desert heat and cold of night. Where the Wood Fey use unique species of plant and tree to direct the wood grains into overlapping patterns criss crossing and brading the already strong fibers into designed shapes including small tunnels configured in ingenious ways to insulate and distribute heat throughout the dwelling. Wispy hydrophobic fibers offers more insolation during the coldest and wettest of days. [Answer] I would like to offer a frame challenge. Given that you've supplied us with four possible ecosystems where fairies might live, each with different resources, I don't think you're actually asking about materials. I think you're asking about overall survival - how do fairies, despite being small and weak, survive in hostile environments? What would a fairy community need to look like in order to guarantee that survival? To give an idea of what I think fairy communities would look like, I want to talk about Beaver Dams. [![enter image description here](https://i.stack.imgur.com/pK7Fp.jpg)](https://i.stack.imgur.com/pK7Fp.jpg) Beavers create dams that disrupt the flow of a stream or river, creating an artificial island where they can build their lodge. Land predators can't easily get past the moat they've built for themselves, birds can't get in through the top, and as a special bonus, they've changed the playbook for most things that threaten them - by turning the river into a pond, more animals will come here to drink, creating an environment where stealth predators have a harder job because of how busy the area is likely to be. Communities of fairies will only survive by working together, and the shelters they construct will probably have more in common with the beaver than with anything human. Rather than individual houses, they will build large, communal structures that can be subdivided on the inside, but which, like the beaver lodge, create artificial barriers for any and all potential predators, while also, by nature of their size and complexity, offer some change to the environment. The forest fairies will likely make structures very similar to beaver dams, using any and all materials on hand. Given that there is a strain of fairy that lives underwater, I'm assuming all fairies can survive in water, meaning that the beaver lodge strategy where the only entrances are for swimming animals would still work. However, i think the fairies would also create an emergency exit near the top, a somewhat loose area in the construction that could be broken from within so that if the river flooded, the lodge could be abandoned and all the fairies could fly out in a swarm. Obviously, the Desert fairies won't have rivers to dam. They can't copy paste this approach. What they can do, however, is move dirt and farm cacti. What I'm imagining is something like a termite mound, but surrounded by a grove of cacti. [![enter image description here](https://i.stack.imgur.com/c9yrb.png)](https://i.stack.imgur.com/c9yrb.png) [![enter image description here](https://i.stack.imgur.com/AQXkH.jpg)](https://i.stack.imgur.com/AQXkH.jpg) Fairies would make natural pollinators, and being intelligent and social, it would be easy for them to use this to control the plant life of their surroundings. In other ecosystems, this wouldn't add much to their natural defenses, but in the desert, where plants come with defenses of their own, it would be very advantageous. (Now that I think of it, Forest fairies may actually do the same thing, seeding blackberry and other thorn bushes around their construction if they can't easily redirect a river) From here, the other two strains of fairy are just extensions of these approaches. Underground fairies build the mounds, but in places where cacti don't grow, so they make the mound less conspicuous, pushing further down into the earth and creating more intricate, hidden colonies wither entrances and exits all across a large swath of land, maybe even taking advantage of existing cavern systems to do so. Underwater fairies make lodges, but instead of artificial lakes off of a river, they are making artificial tidal pools off of a coastline, using clam shells and seaweed as much as driftwood to make more watertight constructions. These constructions would collectively be called Fairy Castles. I imagine fairies living in groups of 50 to 100, building these castles together, and then digging into the ground or into the walls they've built to create family enclosures inside the castle. Depending on where the fairies live they build their castles out of what's available, and keep them intact and and in good repair for however long they need it for. Some fairies may build seasonal castles, some may build ones that last for a few years (long enough for children to grow to adulthood, for example), some may build ones that are effectively permanent. The fairy groups may or may not have heirarchy, may or may not cast out individuals who don't cooperate with the group, but the central idea is, living together as a big collective allows them to make complex structures like this, and increases overall survival rate. ]
[Question] [ Many questions on this site mention how difficult it is for merfolk to develop technologically, as there's almost nothing but rocks and kelp to work with. My solution to this is that they use these rocks to build sea-spires that put them right in the center of maritime trade. These spires would essentially act as a port between continents for kingdoms lacking the economic might, navigational skills or shipbuilding know-how to sail all the way across the ocean. The towers would provide landmarks, trade, shore-leave, ship repair and other services on the jetties ringing the lighthouse like tower. For what the tower is built of, materials acquired from the ocean or close to the shore are preferable. Merfolk can breath & walk, but to them it's like crawling is to us. This means they'll heavily prefer to trade for materials from further inland, making them more expensive and harder to acquire. The deeper and wider the ocean, the more valuable these towers become but the harder they are to build. Can these towers get up and out to a useful height and depth or would the currents and weight topple them before they get out of site of shore? [Answer] Currently, static oil rigs built on reinforced concrete towers are built in sea depths of up to 350 metres. This isn't the limit of the structural mechanics, but more of an economic limit. The deeper concrete structures are built using concave towers (thicker at the bottom and the top). The thicker top actually provides some buoyancy reducing the force on the structure vertically and the slender middle reduces the horizontal force on the structure created by the ebb and flow of the oceans. I very much doubt your Merfolk have the maths, materials and merman-power to create a concrete structure such as this. But, the interesting thing about looking at oil rigs in regards to this question, is that the deeper the water, the simpler the design. After concrete structures, you get into steel frame structures, these go up to 1 km in depth. Still not a material readily available to Merfolk and I doubt the could do the underwater welding required. But next, comes the simplest design. Moored floating platforms. So what is required for one of these? * A floating structure - and us humans have a habit of leaving lots of wooden boats at the bottom of the sea. * Heavy weights to sit on the bottom of the ocean - plenty of big stones in the sea. * Long enough ropes - this is probably the trickiest thing for the Merfolk to get hold of. But those shipwrecks would all have had anchors right? And those anchor ropes could be spliced together. You'd just need enough of them to keep your floating platform in roughly the same position TL;DR - Don't build giant underwater towers, build a floating platform and anchor it in place. [Answer] **Use Coral for the Spires** You could have a giant or fast growing coral that you either use as building material (coral can be as hard as concrete) or use it as the building itself, that could look cool as well. **A joint Building Project** The mer could also get help from the humans to build the top of the sea-spires with the mer building the bottom. They could also send building materials that the mer could not get themselves. You could have symbiotic relationship with the humans, they get a trade partner and a safe haven at sea, the mer get cool buildings that will bring in much needed industry and trade (like smiths and forges) the trade will get the mer items that the mer could never make in the sea i would like to point out the mer have to be careful where they build theses sea-spires as the saying goes location location location. don't build it where the sea is highly active like storms, king waves, and earthquakes. be smart where you build them. [Answer] **Ancient Rome's Underwater Concrete** > > More than 2000 years ago, the Roman Empire invented a unique **marine > concrete** that **allowed for the construction of enormous, durable > structures – even underwater**. Incredibly, the exact chemical > properties of this concrete mixture have eluded scientists to this day > – but now, researchers from the University of Utah believe they may > have finally cracked the code. > > > <https://www.archdaily.com/875212/scientists-uncover-the-chemical-secret-behind-roman-self-healing-underwater-concrete/> --- > > The chemical secrets of a concrete **Roman breakwater that has spent > the last 2,000 years submerged in the Mediterranean Sea** have been > uncovered by an international team of researchers > > > <https://newscenter.lbl.gov/2013/06/04/roman-concrete/> --- Here you see the Merfolk trading with humans from the top of their tower [![enter image description here](https://i.stack.imgur.com/T4KHG.png)](https://i.stack.imgur.com/T4KHG.png) [Answer] I want to frame-challenge the notion that merfolk could not manufacture materials that require being on dry land to make. * humans run refineries that are hundreds of feet tall, yet we do not have wings * humans run fish hatcheries, yet we do not have gills * humans run steel mills, yet we are not fire elementals Just like all those things have catwalks or safety areas for the humans... a dry-land factory would have water-channels for factory workers. So yes, they would simply dig up lime and set up a landside factory to kiln their own portland cement. Of course if they trade with humans, all bets are off. Another interesting wrinkle is nuclear power. Merpeople would struggle to build some of the machinery, but underwater is literally the perfect place for a nuclear reactor. It takes 99% of the "cooling problems that lead to meltdown" right off the table. You would have to labor to keep the reactor core, steam lines and turbine insulated (e.g. By keeping them in air spaces). At first sign of trouble, simply wet the insulation or flood the air spaces, rather easy if you are already underwater. Also, mining thorium/uranium is a fundamentally different task for seapeople; you don't search the world for veins, you simply extract it from seawater, and when you deplete your local sea, currents bring you more. ]
[Question] [ **Disclaimer:** This question, unlike my other tree related question, was brought about by pure whimsical daydreaming. I also threw the term "evolve" around a lot, I should clarify that what I asking is would it be feasible not if it would be likely. **Question:** Could it be feasible for trees in a windy environment to evolve leaves like tethered kites? It would work by instead of having many small leaves they evolve to have one large leaf like a sail. Then the trunk would grow longer and thinner like a kite string, and the roots would evolve to have a more expansive network. Thus having the leaf catch air and "fly" to a higher altitude for more sun. Would this even work or is it just nonsense? [Answer] Well, we know from observation what trees look like that are subjected to harsh high winds that blow constantly: [![Bristlecone pine](https://i.stack.imgur.com/bdjgu.jpg)](https://i.stack.imgur.com/bdjgu.jpg) If trees in this otherworld evolved in a windy atmosphere, then they would probably end up bent over like these venerable Ancients. But, let's think a little out of the pine box: Suppose that the trees in this world evolved within a normal atmosphere: occasional storms, occasional seasonal high winds, plenty of calm airs as well. Now let's suppose that in this region, high winds and storms and fires and so forth occur usually in the summer. One strategy is to blossom and set seeds before the summer storms and fires rage. Plants that do this will be burnt by fire and their ashes and twigs will be swept away. This will leave the seeds already in the ground a happy place to spring up again next year and start all over again. This is not a good strategy for trees, who live for many years. So I introduce the *scarwood tree*. Its wood is dense and sturdy (like a bristlecone's) and its bark grows thick and can slough off in layers when fire touches it, thus protecting the bark layers and wood underneath. But the scarwood, rather than dropping seeds in the late spring, takes advantage of the high winds of summer by sending up long thin tendrils into the windy airs above the woodlands. These filaments grow up and out of the trees' flowers. As the winds pick up, the filaments grow, and at the end of each is a kind of wing-like leaf, much like that of a maple's samara: [![enter image description here](https://i.stack.imgur.com/hvGhf.jpg)](https://i.stack.imgur.com/hvGhf.jpg) But the scarwood's seed has broad thin wings and flies like a kite high on the breeze! As the winds strengthen and the fires approach, the now matured seeds are released at the base of the filament. And they fly away on the wind to a safe distance from the fires, where eventually they'll land and sprout a new generation of scarwood. That is to say: *kite flower trees*! [Answer] Such a species could plausibly live. I don't know if it could plausibly evolve naturally. It would have a trunk, containing a structure like a [spooling station](https://www.cabelas.com/product/BERKLEY-PORTABLE-SPOOLING-STATION/1729189.uts?productVariantId=3680854&WT.tsrc=PPC&WT.mc_id=GoogleProductAds&WT.z_mc_id1=03781335&rid=20&ds_rl=1252079&gclid=Cj0KCQjwk_TbBRDsARIsAALJSObl7nKX68MZY6pgRu5GPGGJG94HEkVi-RDU4yNMbZd37snp9skevf0aAsZMEALw_wcB&gclsrc=aw.ds) (I'm not endorsing this product, its just an example). As the wind picked up, the line would unspool and the kite would take off. This line could always be under some light tension so as the wind dies back down it would wind back up on the spool rather than falling down and getting knotted up. This would be useful for more than just collecting sunlight as well, you could have the tree's seeds be on the kites to be dispersed at altitude. The biggest problem it would have evolving naturally is that the "spool" needs a wheel. This is a problem because they cannot really develop incrementally. A shape won't work at all as a wheel until it is already almost completely wheel-like. There is a reason we don't see any creatures in real life with freely-rotating body parts. Compare this with how sight evolved. Eyes started out as single cells that could detect light and shadow. Slowly, creatures evolved to have larger patches of them, and they evolved structures around them to focus light on them. You can see that they were the product of numerous, small improvements. [Answer] If these grew in a gorge or someplace where it is always windy, I could see it working. Imagine a canyon with constant winds and little sunlight because of the canyon walls. Suddenly some seeds blow in from a small tree. A number of them grow, but tend to be stunted by the low levels of sunlight. Except for one that grew a bit lanky that constantly had its branches bent up towards the top of the canyon by the winds. This tree got more light and produced more seeds, and the weight of its seeds allowed them to fall to earth without being blown out of the canyon. Now lanky trees started to survive, with those growing taller and faster surviving best, until the trees resembled vines, latching to the ground with a great root system and rising into the sky using broad leaves that catch the wind. And boom, kite trees. They only live in this one canyon/canyon system and will die off as the geography changes and the winds stop. Or they will adapt to have slightly bigger trunks and support themselves better, who knows. Life finds a way. Addition: you could have a smaller version of this where the leaves grow on long string like stalks and have special shapes designed to catch wind. When the wind falls, the leaves hang down like on a weeping willow, but when the wind blows they catch the wind and fly behind and above the tree like a bunch of tiny kites. [Answer] What you're suggesting reminds me a lot of lily pads, which have long, thin stalks that allow the plant to receive sunlight from the water's surface while still allowing it to remain anchored in the submerged soil. In order for a plant like that to evolve on land, there would need to be something wrong with the atmosphere that would prevent it from getting enough sunlight at ground level, such as dense, opaque gasses that are much thinner at higher altitudes. However, most plants instead get elevation by growing thick, tough trunks that are are able to support a large canopy of leaves to maximize their sunlight intake, but that requires a lot of time and resources to establish. So, in order to make your design more favorable than typical trees, you need to make your environment more favorable for a thin, quick-to-grow kite tree. Maybe the soil and/or rain in your world is very poor, so there aren't enough resources to support a forest of oaks, pines, etc. Or perhaps the kite trees are able to reproduce at a much faster rate and spread their seeds over a wider area -- such as with dandelions. So, yes, it is absolutely possible for your kite trees to exist and thrive in such an environment; it just needs to benefit them in a way that no other tree can. [Answer] The problem is that when the wind falls below a certain level, the trunk won't be strong enough to hold up the tall tree with the big sail-leaves. In a region where the wind *constantly* blows **hard** your tree might well be viable, but anywhere else it would -- as mentioned before -- fall over when the wind slows. [Answer] Alternatively to *wind* kites you could have plants that use *electrostatic* kites on calm days, similarly to [how spiders use electrostatic propulsion to fly](https://www.theatlantic.com/science/archive/2018/07/the-electric-flight-of-spiders/564437/). Think of giant dandelion looking plants with string thin stalks that use electrostatic propulsion to lift the dandelion heads in calm weather. The bases could even generate an opposing electrostatic field to add to the lift. Also, strong magnetic fields or solar winds (both of which could be rather "constant" forces compared to wind) could be factors aiding in lift as well. In addition, these forces could even be food in addition to sunlight, generating electrical energy the plant could use for nutrient and energy synthesis ([radiosynthesis](https://en.wikipedia.org/wiki/Radiotrophic_fungus), perhaps). It seems plausible that a plant may find an evolutionary advantage by floating past the magnetosphere of the planet (perhaps one with a small magnetosphere) and using solar wind in addition to sunlight. [Answer] Dependence on a single large leaf for photosynthesis is where the plausibility of this takes a tumble. Trees have thousands of cheaply grown leaves that can be replaced when damaged from predation or disease or animal activity, while your tree has just the one. A bad landing when the wind slows, a sudden gust that snaps the tether, disease, or predation, and the sole source of photosynthesis for the plant is compromised or lost entirely. It would then have to regrow, perhaps missing the rest of the growing season just catching up. Another matter is the advantage of this line of evolution. Reliable wind wouldn't be it; wind doesn't block the sun. Competition blocks the sun, so getting as much height over rival trees would be the drive for greater and greater height and larger leaves. But no tree is an island: rival branches would pose an enormous danger to fragile kites, and other kite-trees in the area could entangle their lines, killing each other or just making the species less effective at gobbling up light over all as they spend so much time and resources in recovery from tangles and snagged leaves. [Answer] The problem with this idea is that trees take all the nutrients they need from the soil. In order to do so, they have mostly evolved to have roots that bind them very strongly to the ground, thus making them sessile. You are suggesting a tree that can uproot itself and then plant itself again. It might be possible, but evolution probably didn't favor that on Earth because of the high cost of penetrating ground. Plants here only take to the wind in order to reproduce, such as seen with dandelion seeds and tumbleweeds. Something similar to what you want evolved in water. Most species of seaweed float and don't have roots. They don't need to be hydrodynamic because water will drag them regardless of shape, and they float specifically to catch more sun. ]
[Question] [ It's earlier in the Cold War and tensions between the two superpowers are extremely high. Both are flying regular sorties of fighter craft and strategic bombers loaded with nuclear weapons near the other's border. A particular soviet bomber crew due to unexplained *shenanigans* ends up flying alone, deep in US territory. They quickly realize this, and also that they are too far away to make it back to friendly airspace before being intercepted. US radar/early warning stations are baffled about how this happened, and due to the tension of the situation, multiple squadrons of US fighters are scrambled to neutralize the bomber. The crew do not want to die, nor do they want to be forced down and captured. So they decide to send out a message to any US or Russian radios that are receiving them that the intrusion was an accident, that they will be reversing course and heading back to the arctic circle, and if they are attacked or if US planes approach too closely, they will in no uncertain terms, *deliver* the bomber's payload to the ground beneath them. What is the most realistic US & Soviet response to this anomaly? Would the outcome change if this happened later in the Cold War? [Answer] > > *The crew do not want to die, nor do they want to be forced down and captured. So they decide to send out a message to any US or Russian radios that are receiving them that the intrusion was an accident, that they will be reversing course and heading back to the arctic circle, and if they are attacked* ***or if US planes approach too closely, they will in no uncertain terms, deliver the bomber's payload to the ground beneath them.*** > > > Everything about your scenario is likely, and probably happened to varying degrees, except that last part. Escorting an intruding aircraft out of your airspace is standard procedure. The Soviet crew would have been trained on this eventuality and expected this. There'd be no panicked argument among the crew, that's Hollywood, nuclear bomber crews are professionals. They train again and again and again until every emergency is normal and they can handle it almost literally without thinking. What to do if you blunder into enemy airspace would be one of those emergencies they'd be trained on. They'd follow procedure. Getting an escort reduces tensions by allowing the defending nation to have eyes on the intruding aircraft and know it's taken no hostile action like opening its bomb bay doors, turning, maneuvering aggressively, or using electronic counter-measures. For the crew, who has just made a gross navigation error, it gives them someone to communicate with, even if just with hand signals and lights, and follow out of harms way. ["Russians don't take a dump, son, without a plan"](https://www.youtube.com/watch?v=Rb0QLxcvowk). Threatening to drop their bombs ***without orders to do so*** is the *last* thing a Soviet bomber crew would think to do. A bomber pilot would not have the authority to decide to drop their bombs without orders, nor are they trained to act independently. Taking such a reckless and independent act would be the antithesis of Soviet military and social training. Unlike the US, the Soviet military was tightly controlled. Plans are big and rigid. Junior officers are expected to follow orders to the letter. So that part of your scenario is highly unlikely. Instead, they would follow procedure. That procedure would probably say to declare an air emergency on normal international emergency frequencies and request escort out of US airspace. They'd accept peaceful escort out of US airspace, face discipline when they got home, and the diplomats would deal with the (fortunately figurative) fallout. --- Keep in mind, the Soviets are likely flying the [Tu-95 "Bear"](https://en.wikipedia.org/wiki/Tupolev_Tu-95), a four engined prop driven bomber roughly analogous to the [US B-52](https://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress). Very, very long ranged with a large payload. While it's much faster than you'd think, it's not supersonic, and it has very little hope of fighting or evading its way out of US airspace. [![enter image description here](https://i.stack.imgur.com/mYGr3.jpg)](https://i.stack.imgur.com/mYGr3.jpg) Like the B-52, the Tu-95 soldiers on while sleeker, faster bombers fall by the way side. While the Soviets had supersonic bombers, notably the [Tu-22M "Backfire"](https://en.wikipedia.org/wiki/Tupolev_Tu-22M) analogous to the [US's B-1](https://en.wikipedia.org/wiki/Rockwell_B-1_Lancer), they did not have the range to casually blunder into the US. --- > > *What is the most realistic US & Soviet response to this anomaly?* > > > "*Oh shit, we have a panicked or traitorous crew of a nuclear bomber who might start WWIII!*" Both sides would think this, for the reasons stated above. There's no reason for them to be so terrified of being shot down that they'd threaten to bomb the US if approached. This bomber crew has gone rogue. The Soviets would check the background, mental state, and political allegiances of the crew to find a motivation for their going rogue. Is panic cover for an act of treason? Did they go mad? Are they exhausted and doped up on uppers to stay awake? Perhaps they've been overworked and have been abusing stimulants? One plausible scenario is that a portion of the crew has been incapacitated resulting in the rest being overloaded and unable to catch any sleep. Maybe the commander and navigator are out. The co-pilot and others have taken over their duties. Overworked, stressed, and exhausted deep in enemy territory with [their minds jumbled by amphetamines](https://en.wikipedia.org/wiki/Amphetamine#Psychological), they begin making bad decisions. "*How the hell did they get there?*" With a cruise speed of about 700 km/h, it would have to be a hell of a navigation blunder for a Tu-95 to wind up deep in US airspace without noticing. That's *hours* flying off course. Highly unlikely, even a simple look at the Sun would let them know they're going the wrong way. Both sides would have great suspicion about the crew's claim of a navigation error which would add to tensions. The crew's threat would not help matters. The US would wonder "*how the hell did they get there without us noticing?*" As mentioned above, the Tu-95 is not exactly a sleek aircraft, and to have the range to reach the US it would have to be flying slow and high over the poles. Earlier in the Cold War, US detection systems were full of holes, but later and later they improved. Still, the US early warning system had flaws and things did blunder through. The US would wonder if this was a test of US early warning systems adding to tensions. The US and Soviets would scramble to find out if the bomber crew can follow onto their threat. The US would be asking the Soviets if bomber crew could arm their weapons without explicit orders and codes. The Soviets would be verifying that. I don't know what Soviet bomber procedure was, and neither did the US. If the Soviets can confirm the bomber crew cannot arm their bombs in flight without orders, the US would likely tell the bomber crew to accept an escort, and take no evasive maneuvers. They'd tell their interceptor pilots to shoot the bomber down upon any hostile act such as evasive maneuvers, changing course, or opening the bomb bay doors. There would be hawks in the US arguing to force the bomber to land so they can impound it and its crew. US military intelligence would be drooling at the opportunity to interrogate a Soviet bomber crew and pick over a Soviet nuclear bomber complete with nuclear weapons. Some would be pouring over international law and treaties to build up a legal rationale or loophole. Meanwhile, others would think "*how do we talk these guys down?*" US diplomats would get on the phone to Soviet diplomats and try to patch through Soviet officers to speak with the bomber crew. If they can calm the crew down, they'd then be escorted out of US airspace and into the loving arms of the Soviet military police. If they can't talk them down, it's likely the US would send in escorts in, whether the Soviets liked it or not, whatever threats the Soviets are making. They may wait until the bomber is over sparsely populated territory before approaching. If the bomb bay doors twitch, or if the bomber takes any evasive action, their orders would be to shoot it down and hope the crew did not have time to fully arm the bomb. --- > > *Would the outcome change if this happened later in the Cold War?* > > > It would only make it better. As the Cold War progressed the speed and intensity of nuclear war increased. As more incidents occurred, the danger of accidental nuclear war became apparent, and more and more safeguards were put into place. The later in the Cold War this occurred, the would be easier and faster for the US to contact high Soviet officials to get a confirmation that this is not a sneak attack. Prior to 1963 it would have to go through normal diplomatic channels which could take some time. The [Moscow-Washington hotline](https://en.wikipedia.org/wiki/Moscow%E2%80%93Washington_hotline) was established in 1963. Far from being the iconic "red phone" it was a [teletype machine](https://en.wikipedia.org/wiki/Teleprinter) (basically a telegraph line hooked up to a printer and keyboard), then in 1986 a [fax machine](https://en.wikipedia.org/wiki/Fax_machine) (basically a printer hooked up to a phone line), and finally in 2008 a secure computer link via email. Later on in the Cold War, nuclear bombers would be increasingly replaced with missiles. First and retaliatory strike capability would increasingly move to [ballistic missile submarines](https://en.wikipedia.org/wiki/Ballistic_missile_submarine). Your scenario would probably shift to a rogue nuclear ballistic missile submarine that finds itself damaged deep in Soviet territory. Finally, radar technology would get better and better, as would radios, navigation, and interceptors. It would become increasingly unlikely the crew would get accidentally lost, and that nobody would notice. This would serve to increase US suspicions that this "lost bomber" is cover for testing a new way to penetrate the US early warning system. --- A variation on this scenario is famously depicted for comedic effect in [Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb](https://en.wikipedia.org/wiki/Dr._Strangelove) which if you haven't seen you really should. Dr. Strangelove, a comedy, was based on [the book Red Alert](https://en.wikipedia.org/wiki/Red_Alert_(novel)) (aka Two Hours To Doom) which was not. Red Alert, in 1958, outlined a scenario very similar to your own. > > A US Air Force general considers war with the Soviets inevitable and decides a preemptive attack is the only option. He uses a procedure designed to give him authority in case the US government is knocked out in a first strike to order his bomber wing to attack. The book is about the cascading consequences of procedures designed to expedite nuclear attack. > > > [![enter image description here](https://i.stack.imgur.com/Ycbro.jpg)](https://i.stack.imgur.com/Ycbro.jpg) [Operation Chrome Dome](https://en.wikipedia.org/wiki/Operation_Chrome_Dome), the US operation keeping nuclear bombers continuously in the air from 1960 to 1968 to keep a credible second strike capability ready, made these scenarios even more likely. [Trinity's Child](https://en.wikipedia.org/wiki/Trinity%27s_Child), and the movie adaptation [By Dawn's Early Light](https://en.wikipedia.org/wiki/By_Dawn%27s_Early_Light), are another similar similar scenario. The book and the movie differ in their details, but both depict attempts to stop a nuclear war and recall bombers. The film [Crimson Tide](https://en.wikipedia.org/wiki/Crimson_Tide_(film)) is another film with a similar scenario, but this time it's a US ballistic nuclear submarine. > > A US submarine captain gets a partial transmission that looks like a launch order, but is attacked and forced to dive. Its radios are damaged. The captain believes nuclear war has begun and wants to launch. His XO (second in command) wants to wait until the radio is repaired to verify the order. An escalating fight for control of the sub ensues. > > > [Answer] ## They wouldn't want to escalate on their own The premise of "send out a message to any US or Russian radios [...] they will in no uncertain terms, deliver the bomber's payload to the ground beneath them" is unrealistic, because by doing this without approval they deny themselves any chance of a reasonably good ending. Being shot down and captured or dying in service is understandable, and might be requested from them by the authorities - i.e. destroying key components and intentionally crashing the bomber. Doing what you describe is treason. No matter what the consequences were, even in the best scenario, these actions would mean that they would get arrested on landing. By the time they get to USSR, their families already would have been collected for interviewing, and if a difficult order would be made, their future would be used for "leverage". The consequences would depend on the decade, but they would be expected and they would take them into account when making a decision to do so, and it's realistic for a military man to execute a near-suicidal order rather than return home, get executed anyway, and have their family tortured and punished as well. If one officer made this broadcast, it wouldn't be surprising if the others preferred to shoot him and defect to USA rather than return home and face these consequences. ]
[Question] [ In the near future, screens and technology will be implanted in us so we do not need to have another physical device. When a person is in prison, they are not allowed to have access to technology and other resources without permission. How would this be handled if the technology was implanted? Would it be ethical to forcefully remove the device on the start of the prison sentence? What about in jail before the person is convicted of a crime? [Answer] Either remove the tech in question, or even better, lock it down, and use it to further monitor and control the inmates. That tech can be used to educate / brainwash inmates by constantly broadcasting educational programs, or offering them some entertainment as a reward for good behavior. Furthermore, you can probably tap into what they're looking at at any given time, and even "blind" them if they're actively involved in a fight, or mischief. [Answer] Here's the deal with crime and punishment. Generally speaking while prisoners in some countries retain SOME rights they lose rights in every country while incarcerated and sometimes, depending on the severity of their actions lose rights even after serving their time. ## Ethics is a matter of social norms. Not right and wrong. You can claim that ethics is based on good versus evil or religion and therefore ethics is innate and immutable but that is simply not true. Take the Catholic church as an example. It silently consented to the trans Atlantic Slave trade. Burned scientists and *witches* alike...and a whole host of other sins aside. **As society changes, rules change.** So. That in mind. *Your society dictates what is ethically acceptable within said society.* --- The only *mostly* universally agreed upon human rights are the basics (the UN bill of human rights is delusionally optimistic and VERY western/progressive, and as such wouldn't use it as a baseline). That being: Food, Shelter, Water ...but that's about all we can usually agree upon as human beings. Taking a cell phone out of your arm doesn't really violate any basic human rights. If your society agrees that it is not a violation of rights for a prisoner to lose these privileges then you're good to go. [Answer] # Maintenance Override There must be some way to get into the system, install a new version of the firmware (*now with 20% fewer bugs!!!*), reboot it after a crash, etc. After the first cases have wormed their way through a series of administrative orders, court injunctions, decisions, and appeals, there will be rules that inmates must surrender the access codes to their systems. What can or cannot be done depends on the political climate at the time, perhaps data cannot be used but the system can be shut down, perhaps there will be a full download for analysis by police AIs, perhaps the system will go into some sort of "airplane mode" with stand-alone use only. # Remember Medical Implants It is quite possible that implants for medical purposes will be common before "elective" implants reach the market. Pacemakers. Hearing aids. Artificial eyes. Prostetic limbs. Taking that away from an inmate, especially one who is awaiting trial and not yet found guilty, might be a civil (or human) rights violation. Note that in some places in the world, inmates have a *right* to free and adequate medical care. That might even include new implants if the old ones wear out. If the legal precedents are set with medical implants in mind, your story could get interesting ... [Answer] So it kinda depends on what the implants do. If you watch anything about prisons, you'll see what a bored person with a lot of time can do with very minimal resources. Making a weapon out of a toothbrush, or a bit of stone, or compressed paper... So leaving even deactivated hardware is just asking for trouble, because all you need is someone that figures out how to reactivate it, and you'll have inmates getting up to mischief. Even if they have to carve into themselves to turn it on. But there is also a case for allowing limited technology use. Some prisons [have been rewarding prisoners with tablets for good behavior](http://www.freep.com/story/news/local/michigan/2016/01/03/jail-inmates-tabelts/78227246/). Some implants might have a health reason, such that removing or disabling them might cause the prisoner to die, so that should be taken into consideration. Now stepping a little closer to the ethical line, if you have bio implants there might be a way to use implants to the benefit of the prison. Maybe implant something that shuts off nerve impulses down the spine and temporarily cripple people at will. So you have a prison riot start, the warden just flips a switch and all the prisoners fall down. The ones that need medical attention get taken to the infirmary, the rest get dragged to their cells, and then when everything is secure you turn them back on. Take it one step further, and you can put a trouble maker into solitary right in their own head. Enter a command and their hearing, sight, and maybe other senses just stop working. Another step over the line and you make all signals register as pain... [Answer] One easy answer would be a futuristic version of "MAC address filtering" where the unique ID of wifi cards are filtered to allow access to a wireless network or deny it (less often used). In the scenario you describe, the hapless prisoner wouldn't have his tech removed as much as disconnected or - based on Bellerophon's comment to your question - un-powered/switched off. [Answer] This is where you run into an odd confluence of convenience, security, and ethics. One of the things you have to do to control the prison population is to control communication with the outside world, but it would be unethical to totally remove the ability in a permanent way. Implants would be a grey area, because that would impede communication, similar to cutting out a prisoners tongue. On the other hand, you can always replace the implants. Any number of blocking, jamming, or other techniques might be used for short term incarceration like between arrest and trial. The protocols would have to be different for those incarcerated for long periods of time. Perhaps the minimum security prisoners will just have the implants bricked temporarily by firmware update, since sentences are shorter, and the surgical removal would probably be expensive. When the convicted prisoner reaches their long term destination, The most secure thing might be to actually remove the prisoners implants, replacing any which are health related with secure, prison versions. almost any technology is going to be hackable, and we have learned that, given time, the bad guys will find ways to circumvent anything software related. Imagine what would happen if a prisoner uses his own implants to start messing with the guards implants, like a phone call signal to distract the guard just long enough to get something sharp in between somebody else's ribs. Also keep in mind that humans are clever monkeys and will not only circumvent your security, but will find creative and unpleasant ways to use it against you. You would be amazed at the 'harmless' objects that can get turned into shanks in a prison. [Answer] ## Just Fry It Use a targeted EMP that will destroy the tech. I'd imagine the cost of such tech is pretty low, so if they're a certain level of criminal, you just copy the data from it, fry it, and then reimplant something after they're released. ## Block the Wireless There are so many different technologies to inhibit wireless transmission that for low-level criminals who'll be released quickly or pre-convicted/sentenced criminals you can just create a wireless hole. This could also be targetted into only specific areas that guards aren't always inhibited, but prisoners always are. [Answer] Similar to Jym's answer, I'd use a pharadehic cage around the cells and/or prison. This prevent's data from getting into and out of the proson, to prevent the planning of an escape. However, if a prisoner is reasonably smart, he would also have the blueprints of the prison on a harddrive on him, maby a hidden drive. Now, I'd say, here comes the severeness of the crime into play. In my option it would be a total overkill to fry all the electronics, in one, that is arrested for alcohol abuse while driving. How ever, how would you deal with such a situation? There are multiple ways to do so. The easiest would be to reset or whipe the hard drive. However, the disadvantage of this method can be, that the data could be recovered. Or you could install a virus or some other malware and use ther tec for your own advantage. You know everything of everyone at anytime, vital signals... And the best thing is, you don't have any costs for doing so, it's completely free to use and comes built in with most prisoners. Leave your creativity of the leash for further Ideas... [Answer] Removing the tech when someone enters prison isn't ethical. Neither is locking humans, which are social creatures, into Solitary Confinement, which has been proven to have extremely negative mental health effects. Yet, despite the toll on the inmate's sanity and the rights of human beings, Solitary Confinement for long periods due to bad behavior, or even permanently due to an inmate being particularly risky to contain, is the standard operating procedure. No, it isn't ethical to remove it. But that's not going to stop those running the prison from DOING IT ANYWAY. [Answer] # If you can't take it away, add a new one instead. If there are laws against removing a person's implants, and there aren't safe, easy ways to disable them, then one option is to give them a new inhibitor implant. This device monitors any other implants they have for signs of activation, and delivers a debilitating electric shock, or dose of sedative if the prisoner starts to use their implants. The prison staff have the control codes for the inhibitor implant, so it can be fully disabled once time has been served. ]
[Question] [ Moreover, could a culture of microorganisms form a collective hive-intelligence similar to ants or bees? I'm trying to design a scientifically plausible hive-mind, and I'm trying to decide whether the best option is to merely utilize tiny aquatic insects with the conventional type of hive-intelligence displayed by certain species on Earth (only extrapolated so that the hive, when working together, is not only conscious but can out-think the entire human population or a futuristic supercomputer), or to create bacteria with some primitive level of intelligence that can communicate with others of its kind over long distances, possibly via radio waves, to form a giant brain with distributed intelligence like an octopus. Which of these is more plausible scientifically, and which would seem more different psychologically when compared to humans? [Answer] Of the two, I would go the bacterial route. But before I explain my answer, I feel I should point out that in either situation, the **individual organisms are not intelligent**. Intelligent organisms that collaborate to become smarter than an average individual is known as Collective Intelligence. It is very easy to think that the flocking behavior of birds or the herd mentality or even schools of fish are the results of some particular intelligence on the part of the animal. It is not. It all boils down to some very simple rules of behavior like "never be on the edge, more than 3 feet from another fish, never closer than 6 inches, and never get closer than 6 feet from ABC". Also, as @ThomBlairIII points out in his excellent answer, humans can be thought of as a macroscopic colony of microscopic "organisms". A skin cell is not intelligent, nor is blood cell, or even a single neuron. As a whole however, I am able to add 2+2 (but beyond that is questionable at times). So now to actually answer your question. Were you aware that the [amino acid alanine was used to store quantum data](https://www.theengineer.co.uk/issues/september-2001-online/scientists-protect-quantum-information-in-a-noiseless-subsystem/)? And I'm sure you're aware that [cells routinely work at the subatomic level](https://en.wikipedia.org/wiki/Proton_pump). With just that knowledge, one could imagine a "coral reef" bacterial system comprised of species of bacteria that collectively form a quantum computer. One species gathers protons and creates ions, which another species can use to get the electrons. During cellular division, they release a few electrons causing a pulse which causes a bacteriorhodopsin to "kink"...etc. Eventually the entire system forms a living quantum computer that is able to "out-think" (although "out-problem solve" is probably a better term here) humans and their computers without being an omniscient god-like being. Just as it takes time for my heart to pump blood to my brain, so too would it take time for the bacteria to get enough sunlight or heat from a thermal vent or in order to set up the quantum states needed to solve the problem. Thank God this isn't a Hard Science tagged question! :D --- **Edit**: I started thinking about the tactical applications of a quantum system. Imagine an enemy that looked at your current troop deployments and instantly ordered its troops into positions ensuring victory! That is, if a quantum computer were given the current state of a chess board, could it collapse into a strong solution? I had to Bing this... and (as usual) [someone else thought of it first](https://www.chess.com/blog/watcha/limits-of-quantum-computing-in-solving-chess). If you read that article, you learn two things: 1. "*Can quantum computers solve hard problems quickly? The answer is: yes and no. ... Integer factorization is important practically because many encryption methods rely on the fact that integers having very large factors can only be factored in ridiculously long time using classical computers, making the encryption unbreakable. However this problem has a structure which favours a quantum mechanical solution: namely it boils down to finding the period of a function which is 'easy' for quantum mechanics. ... There is no such natural phenomenon that chess models in an abstract way. It models war fought between humans in an abstract way which is a different story. It is one of the many problems that can only be solved by brute force and this is hard for even quantum computers*." **Bummer!** 2. (More intriguingly) Both I and @JDługosz are late to the game. [Nature already works at a quantum level](https://www.sciencedaily.com/releases/2014/06/140616151509.htm). So maybe a story about algae being a quantum computer would be less a science fiction book and more of a text book! [Answer] ## Volvox [Volvox](https://en.wikipedia.org/wiki/Volvox) is a genus of green algae that forms spherical colonies of up to 50,000 cells. [![enter image description here](https://i.stack.imgur.com/IEzyU.jpg)](https://i.stack.imgur.com/IEzyU.jpg) **Volvox colony:** 1) [Chlamydomonas](https://en.wikipedia.org/wiki/Chlamydomonas)-like cell 2) Daughter colony 3) Cytoplasmic bridges 4) Intercellular gel 5) Reproductive cell 6) Somatic cell > > Each mature Volvox colony is composed of up to thousands of cells from two differentiated cell types: numerous flagellate somatic cells and a smaller number of germ cells lacking in soma. Adult somatic cells comprise a single layer with the flagella facing outward. The cells swim in a coordinated fashion. The cells have anterior eyespots that enable the colony to swim towards light. > > > Here, a distinct hive-like mind exists--they all cooperate to swim in a certain direction and they process visual data, so that demonstrates a definite complex communication between individuals. In addition, Volvox can be sexual or asexual. In sexual colonies, male colonies release numerous sperm packets, while female colonies produce single cells that enlarge to become eggs. So, they even coordinate to mate. While Volvox are not using radios yet, it's still proof microorganisms can form hive-minds capable of complex behavior. So, it's not that big of a leap to imagine more evolved colonies capable of more human-like intelligence. ## Humans As Gestalt Entities In fact, when considering how individual Volvox cells differentiate to perform different tasks, i.e. have an eyespot or a flagella, their growth and organization bears a striking resemblance to how groups of [human stem cells](https://en.wikipedia.org/wiki/Stem_cell) differentiate to form humans. In that sense, humans could be considered a macroscopic colony of microscopic differentiated stem cells possessing a very highly evolved group mind. [Answer] ## Could an individual cell or group of cells have intelligence? I think it is possible for an individual cell, and hence a group of cells as well, to have intelligence. The real-life example I'm basing this on is the precise, well organized functioning of [cell organelles](https://en.wikipedia.org/wiki/Organelle) within a [eukaryotic cell](https://en.wikipedia.org/wiki/Eukaryote): [![enter image description here](https://i.stack.imgur.com/MfBRB.png)](https://i.stack.imgur.com/MfBRB.png) Essentially, such a cell is an organism just like a human, complete with mini organs (organelles) that perform specific tasks. For example: * Brain - Cell Nucleus * Skeleton - Cytoskeleton * Limbs for movement - Flagellum These organelles perform complex tasks requiring great precision and very low error rate. As such, they could be considered extremely "intelligent", just as a human engineer can be said to be intelligent and not just a mindless mechanical contraption set in motion by chemistry and physics. So, I think it's plausible to posit some cells could indeed evolve to be intelligent, particularly if they evolved in an environment favoring microscopic evolution much more than Earth does. [Answer] Search for articles on 'physarum polycephalum maze solving' and you'll see that biologists have been amazed at the ability of this slime to solve mazes. Also interesting to note that this slime will group in blob or slime in periods of least food availability and resume ´individual' life when food is plentiful. However one challenge with considering a super blob of planetary size would be the diminishing returns due to communication cost across all cells. You might want to consider blobs of blobs or super blobs like the super ant nests of Amazonian ants. So specific blobs tackle in small committees specific problems. This also allows some of them to fail. This could make it temporarily look like our world. But if the blobs where to constantly form and dissolve with each single cell retaining the ability to leave the bigger blob you could keep the framework of your story. You might also consider throwing panspermia in which could give you a startravelling species. [Answer] Yesno. Yes, a bunch of micro-organisms working together can get reasonably intelligent. An average human is, after all, merely 30 trillion or so cells. Each of these cells (or rather their ancestors) started life out identically, as a completely undifferentiated stem cell. Each of these cells is *very* simple. Together they can form an almost-convincing facsimile of an intelligent being. So a human is just a colony of 30 trillion cells, that cooperate to such an extent that they have even delegated control (nerves) and propagation (germ cells) to subgroups of the colony. But, is this not *exactly* the sort of specialization that a colony of insects do? The "no" part of the answer comes from exactly which definition of "organism" you are using. You likely require the bits to be individually motile, like bees, rather than almost-permanently glued to each other, like human cells are. [Answer] These answers all seem bad, so I'll add my own. In our world, there are no known mechanisms of computation that exist within a single, individual cell. From time to time, someone posits such a mechanism, but those are fringe science as far as I'm aware. Thus, single cells are never intelligent, not even single neurons. However, there is nothing in physics, chemistry, or biology to suggest that this is impossible. Computational mechanisms could easily be small enough to fit within a cell, and could be made of the sort of organic substances we tend to find in cells. Greg Bear wrote a novel about this (*Blood Music*, I recommend it), where a mad scientist type engineers bacteria that are individually as intelligent as humans. For the purpose of your question, if intelligence is Turing computational (unclear, but no reason for it not to be), and if sufficient computational density could fit within a single cell, then they could be as intelligent as any other larger organism. There are probably limits to their intelligence (doubtful single cells could be superhumanly intelligent), but without a clearer picture of how those computational elements function it's difficult to give much more than speculation on that. Biologies that are more alien than Earth's probably allow more leeway, it wouldn't be implausible that some inorganic crystalline life forms would grow something akin to computronium. [Answer] I do not believe that in the real world they can possess a hive mind like that of bees but I do believe they can all share the same primitive goals such as moving in huge swarms or by locating others of its kind through a sort of energy pulse. So I dont see why this could not be a thing, but if they did form a hive mind I think it would be very very primitive. This idea of your reminds me of something out of Dr. Who. There was hive like creatures in one of the episodes. ]
[Question] [ Eyes that constantly emanates light, either just the iris and pupil (resembling a tapetum lucidum reflection, but visible from any angle) or the whole eyeball. Could a person still see or would they get blind? Or would they evolve and get more resistant photoreceptors? Or they wouldn't see anything because of the eyes' light? [Answer] One way to give a glow without causing vision problems would be if that glow is monochromatic (just one frequency), and at the same time that person happens to be blind for exactly that frequency, without affecting vision of any other frequency. That way his seeing would only be minimally affected because most things we see have a very wide spectrum (Lasers being an obvious exception), and even if they don't, it's unlikely they would have exactly that frequency. And the glow itself would not affect the seeing because, well, that person doesn't see it. An interesting side effect would be that the person would be completely unaware of the own glowing, unless someone told the person about it, or it is revealed e.g. in a video (the video camera would, of course, not be blind to that frequency, and the replay would then be in frequencies that person can see). Another possibility to detect the own glow is through fluorescence: Since usually the wavelength emitted by the fluorescent substance is larger, it would be visible to the person, who would then observe fluorescent substances to glow on approach. [Answer] A light source inside the eyeball, bright enough to be visible to observers, would wash out any focused image on the retina. It's possible to see under such conditions, since the retina and visual cortex respond to changes in light level and not to sustained light, but it's hard to believe that such a person could see very well at all. Individuals do not evolve; only populations do. A light source on the outside of the eyeball, that did not extend close enough to the pupil to be visible, would not directly wash out retinal images. However the glow would be reflected by any dust or smoke in the air and would noticeably interfere with good vision, especially in low light conditions. So if the mutation involved all the tissue in the person's body, then the inside of the eyeball would glow, and it would definitely result in a disadvantaged or impaired vision. But if the mutation and consequent glow were confined to the skin, then it would plausibly make the whites of the eyes glow, but only on the outside of the eyeball. This would probably ruin the person's night vision but otherwise would just be a slight handicap. [Answer] The question isn't really whether or not they'll go blind, it'd whether or not the signal to noise ratios will be high enough. If somebody is `20 ft` away shining a `100 Lumens` flashlight with a beam width of `20 degrees` (which is somewhat small) and your pupil has a diameter of `4 mm` (which it may at average ambient lighting), `346 micro-Lumens` will enter your eye. If a firefly were `2.8 cm` away from your eye, it would be just as bright. If your eye produced even the same amount of light internally, you'd never be able to see that kind of a flashlight. You wouldn't haven an issue during the day, but you would be ridiculously easy prey at night because you wouldn't be able to see anything. [Answer] Just make the eye white glow. That area of the eye is already opaque enough to block so much bright daylight that we see just fine during the day, so some surface bioluminescence shouldn't penetrate it much if at all. You would still have reflections to deal with, hampering low light far vision, possibly quite a lot, but something like a torch should still be just fine (bright enough) for illumination in the dark. And close vision wouldn't really ever be in the dark anyway, their own light should be usable for reading distance. If you want pupils to glow too, consider just reflective retinas for that. --- Bigger problem would be tip of the nose! They'd either need very flat nose so they wouldn't see it, or they'd need to cover it! Though simple dirt/mud should work for that quite well even,in a no-tech situation. [Answer] A continuous glow would not matter much at all in decent lighting, though it could matter in very dark situations. Our eye doesn't actually see exactly what, say, a CMOS camera might see. We have all sorts of interesting processing built right into our eyes and brain. One of these is lateral inhibition. If one part of the retina is firing, it suppresses nearby areas, thus at the optic nerve level, we see something resembling the edges of the scene. This is converted into what we think we see later in the vision process. If you had a uniform glow, this would rapidly get tuned out, and the person would see just fine. The one place I don't think this would work is at night. At night, our eyes undergo changes known as the [Purkinje effect](https://en.wikipedia.org/wiki/Purkinje_effect). This change to night vision does things such as shifting our vision away from the cones and into the rods. The rods rely on a chemical known as rhodopsin, which is maintained in an incredibly intricate balance such that a rod can be triggered by a mere 5 photons! However, to do this, the system has to go through a very long calibration phase, about 45 minutes, where it tunes all of the rods which were overstimulated during the day. (This is why, when someone shines a light on you at night, you are blinded for a quite a long period. You wreck the delicate balance in the rods, and they have to calibrate again). In low light, that glow would generate far far more photons than the rest of the scene, and would make for a much harder calibration. ]
[Question] [ I'm not talking about stuff like radiation and mutations. I'm talking about mechanics (for now). Necessary effects: With superstrength, you can... * lift objects weighing many tons without your feet sinking into the ground * lift heavy objects at arm's length without overbalancing * lift structures otherwise not capable of supporting their own weight With superspeed, you can... * land a supersonic punch without hurting your hand, yet still be vulnerable to bullets * land a supersonic punch on a normal human without killing them * run without worrying about the supersonic impacts of your feet making holes in the ground A "tank/brick" character (strong and tough, not necessarily fast) has to be viable in a fight against a speedster. That is, the brick's fighting style relies on standing his ground. Without being particularly large or heavy, he must be harder to knock over with a high-speed impact than a normal person. A brick can make high jumps from a standing start. A speedster can't. The relation of speed to damaging ability is different than in reality. Even against normal humans, high-speed or sharp objects can still harm them, but low-speed impacts of massive objects are rather ineffective. A giant doesn't have a problem with sinking into the ground. Changing size changes your carrying capacity proportionately. A giant ant can lift many times its body weight; a human reduced to the size of an ant can't. My initial thoughts / proposals: The brick able to hold his ground suggests he has (passive or active) increased inertial mass. This in turn suggests that speedsters have decreased inertial mass. That is, it's not that they can generate more kinetic energy, but they can move faster for the same energy. Thus, their punches don't carry as much energy as a mundane object impacting at that speed. Because gravitational mass is unchanged, they can't jump as high as their speed would suggest. However, I don't think this explains why the Hulk *is* able to jump high. Looking at it a different way, the underlying philosophy isn't "I have more money, so I can buy more." It's "I can buy things at lower prices." Properties of the world appear to matter only relative to your own capabilities. In essence, Superman can lift a car by its bumper not because he's exerting the tons of force needed to lift a car normally (which could tear the bumper off) but because, from his perspective, the car weighs less and he can lift it with less force. Likewise, it's not so much that the Flash moves really fast; it's that everything else is in slow motion from his perspective. The square-cube stuff fits with this principle: doesn't matter if I get bigger or smaller, this patch of ground is still a flat surface made of the same material, it just looks like it covers a different area. I don't have a physical interpretation of this part, though. The part about a speedster's punches and the part about mundane weapons might be consistent. It seems that the laws governing collisions are different in the super world. In an inelastic collision, kinetic energy is preferentially absorbed by the slower-moving object. Note this requires an absolute rest frame to be defined. This explains why a speedster isn't at serious risk from collisions with stationary objects. This greatly increases the damage-dealing advantage of high-speed low-mass objects over low-speed high-mass ones, creating broadly the correct effect in mundane combat. It explains the Juggernaut's unstoppable charge (or for that matter, the bus in Speed being able to ram cars with impunity - non-superhero action movies share a lot of these physics), and that bullets don't deform on impact. This is just to show what I've considered already. Some may be redundant, some is insufficient, and I haven't fully reasoned out the other consequences of these. That's what I'm asking for help with. Always assume a weak anthropic principle. Whatever laws this universe operates on, it must be able to have planets and recognizable life. To clarify, given the direction the answers are taking: The objective is not to justify super-powers in our universe. The idea is that even normal humans experience many things differently, since superhero physics appear to be a special case of action-adventure physics. I recognized from the start that many super-powers make more sense as psionics. I neglected to mention that because I thought I made clear the approach I was taking. I want physical super-powers to be a consequence of, not an exception to, this world's standard physics. [Answer] My answer is really similar to dsollen's, but I think there's enough added that I'll go ahead and post it. The key here is your statement: > > Properties of the world appear to matter only relative to your own capabilities. > > > **And the solution is that all superpowers are psychic powers**. Which is to say that normally when you classify superpowers you might put them into logically categories like physical (strength, speed, toughness), psychic (mind reading, telekinesis), magic (ritual, fireballs), and so on. But what if instead all powers are actually just psychic, and are driven solely by the user's mind? This solves a lot of problems. **Awesome Lass** isn't actually super strong. If you take a sample of her muscle tissue, you wont' find it any different than tissue from Suzy Sue, intrepid reporter at the Periodic Comet - it's just basic muscle. But Awesome Lass can lift a car, and Suzy can't, because Awesome Lass has powers and *knows* she can lift a car. And this explains why she can lift it by the bumper, when logically she should just rip it off - her power is driven by her mental framework. Even if she later learns that she should be ripping the bumper off when she lifts, she knows she's done it in the past. Alternatively, her friend **Strongadacious Dude** was originally a physics major, and he can't lift cars by their bumpers because he knows how it should work - he has to find the center of mass. The neat thing about this is it allows powers to be logically inconsistent, because they are largely based on individual human knowledge and expectations. **Speedy Guy** *should* be able to block a bullet just like he blocks the wind at Mach 10, but that doesn't have anything to do with Speedy Guy's perception of his power, so it doesn't work. **Stupendous Sally** should sink into the ground since she's 50-feet tall, but her power holds her up and lets her ignore the pesky problems with the square-cube law. There are some interesting implications of this approach: 1. Ignorance = flexibility. Knowledge = power. Awesome Lass can lift a car by a bumper because she doesn't know any better, but she's doing it the hard way - her power has to help balance and hold the car together instead of just lifting. Strongadacious Dude is lifting directly, which means he's using his power more efficiently - which means he can lift twice as much as Awesome Lass, as long as he takes things like structure and the center of balance into account. Speedy Guy can run through a city at Mach 10 without blocking out windows from a sonic boom, because that's not part of his power. But his rival **Superfast Fellow** can go Mach 15 and block bullets just like wind - but he does a ton of property damage at the same time. 2. You might see additional powers develop over time, as situations occur where heroes (or villains) need them. Suddenly Speedy Guy can lift a car, because that's the only way to save his wife. Alternatively, people might learn how to use their powers more efficiently over time subconsciously, so they'll get stronger overall. 3. It might be possible to lose powers as you learn more. So maybe once Awesome Lass figures out she shouldn't be able to lift cars that way, suddenly she can't. This could go so far as to having heroes lose their abilities entirely. The final thing you need to worry about here is a power source. I would probably go with some sort of handwaved tap into dark energy - we know it exists, maybe superpowers let people tap into that to do superhuman feats. Alternatively, maybe heroes have a direct matter-energy conversions engine organ - extremely dangerous, but lots of power. [Answer] This is a *really* tall order. I don't think you can really get a fully logically consistent physics. The best you can do is a hand wave that sounds plausible enough that people don't think too deeply. My best idea for the BRICK would be to go with the concept that is canonically superboy's power set, tactile telekinesis. They are not super-strong, but instead of a form of telekinesis that is limited. They must touch the object to exert their telekinesis, either because the field must expand out from their body to work or because they lack conscious control of the telekinesis and so their subconscious is using it tactile only. This solves a huge number of problems that come up with super-strength. It explains why someone doesn't sink into the ground when they lift something hard, why the airplane's wings don't snap off when they try to lift the plan by it's wing, why the equal & opposite forces of throwing a gigantic rock at someone don't result in their being tossed backwards into a building etc etc. A similar explanation can be used for their super-suitability. The same telekinetic field could be surrounding them. speedsters can't knock them over because they are using their telekinesis to hold themselves up! The speedster could be explained with a similar approach, though it works a little less with him. Perhaps he propels himself with a similar sort of telekinesis ? It works better if instead of moving his legs super fast he simply hovers centimeters above the ground and pushes himself at high speeds. Of course this is more limited then the traditional speedster concept, he wouldn't be able to read or type at a computer at super speed for instance. Furthermore if he didn't have super-evolved reflexes he would still be quite vulnerable to anything that would force him to move quickly. His telekinesis may allow him to stop or turn fast when used, but he is still limited by his slow human-mind in recognizing threats and adjusting. The speedster can survive hitting things with massive force because he doesn't hit them, his telekinesis does. perhaps that spreads the force from his one fist across his entire body, slowing him down rapidly but lowering the impact on any one point to a manageable level. I think this approach works best if we explain the differences in telekinesis control coming down to the concept of "the human mind can't fully comprehend telekinesis " In theory it would be possible to fling spaceships by looking at them, but we haven't evolved to be able to do that and no one really knows how to make themselves do it. Instead we use our telekinesis to enhance things that come naturally to us anyways and subconsciously the telekinesis 'just works' Of course, one still needs to explain where the telekinesis came from. Honestly I'm half tempted to suggest you don't try to explain any further. Saying "we figured out how to make telekinesis work" is one single hand-wave that you can get people to accept due to suspension of disbelief. Set consistent rules for how it works and just explain them. Trying to explain exactly how the telekinesis works further is likely to do more harm to suspension of disbelief then good, since once you bring up specifics people think about it harder and realize all the reasons it doesn't work. However, if you do wish to try to go into more specifics, using modern physics, lets try something like this: In the near future we have a revolutionary scientific breakthrough about how to control forces around us. We discover how to use a device to convert physical energy into potential energy and back again rapidly. It does this by projecting a special field of waves around the objects, and it can absorb or transfer energy across anything that passes through this field. The really interesting thing here is to abide by thermodynamics and conservation of energy, which implies some cool limits to your superheroes. Imagine that your Tank goes in with a mostly full 'battery' of energy powering his field. When he lifts up a car and throws it he needs to transfer a significant amount of kinetic energy into the car to counteract gravity to lift it up. He can throw the car at someone by converting more of his potential energy into kinetic, the equal & opposite recoil doesn't occur because that kinetic energy is converted to potential. He will be using up lots of kinetic energy as he throws items around. However, when the speedster runs up and hits him with supersonic force his field does the opposite, converting kinetic energy into potential energy. This recharges his 'battery' partially, giving him more energy to fuel his car throwing later. If he every uses up his 'battery' entirely he will be merely human. As the speedster keeps being hit by punches from the tank he converts that energy into potential. However, his capacitor is limited as well, and eventually if he absorbs too much energy it can be over loaded and go boom. so no soaking up punches forever. Of course entropy means that energy will have to be constantly lost with these exchanges. if they just trade punches back and forth both's batteries will slowly degrade as more and more of that energy dissipates due to entropy, maybe expanded across the entire electromagnetic spectrum to spread it out enough that it isn't harmful to anyone nearby (plus it's cool that a really strong punch actually causes a bit of a light flash that humans can see lol). To further limit superheros from trading punches back and forth forever you could also imply that this device requires a unique fuel source, and they use it up as they trade energy. Thus the speedster isn't too worried that he is 'feeding' energy to the tank by hitting him, because he is still wasting the tanks 'fuel' by forcing him to have to convert between kinetic and potential energy. Lets also put an upper bound on how fast one can convert between energy sources. If you get hit with a hard enough strike your field won't be able to covert the kinetic force into potential energy fast enough. Your going to feel the impact and be hurt by a powerful blow as some of the kinetic energy slips past your field and hits you. The more energy that your hit with the more that slips by, but it's not linear. If you get hit with X energy maybe 0.1x of it will slip through your field. if you get hit by 2x 0.15 slips through. 10x force lets 0.2 through etc; more force means more impact, but it's not where you can absorb exactly X without difficulty and anything over X will be fatal. The other question is why we would use this to be superheros, when the technology has so many other applications. This is a real issue with almost any approach you use to justify superheroics. The best explination I have is that the power is limited to human minds and we use it the only way our minds know how to; theoretically it could be used other ways but we don't yet know how to harness it as such. For instance try out this scenario. When they discover this amazing technology they also find a key weakness. Their best computer simulations are incapable of doing the calculations required to figure out how to exert this field accurately. Limitations on how we do calculations mean we are unable to generate a proper model quickly enough and thus we apply the energy translation field unevenly. This tends to result on very different forces being exerted across the body of an object, which ultimately lead to tearing it apart in a very unpleasant manner. It's unsafe to use computer controlled fields. However, there are certain processes that human mind does *much* better then computers today (vision recognition, facial recognition, spacial orientation/awareness etc). In the near future we have not gotten any better at making computers do these sort of processes, thus the failed fails. However, in this near-future we have started to figure out the basis of computer to neural interface, connecting computers into our brains. Thus machines to control these fields are connected into the human mind. The human minds own unique processing ability is used to supplement the computers and do those calculations computers are still terrible at. The problem is that the human minds are not human computers, we can't just plug into a human mind and tell it "figure this out for me". Instead we need to 'trick' the human mind into doing it's own process recognition and have the computers 'listen in' for the answer to the calculations it needs. This results in computers only being able to apply the field to those things that the human mind is already thinking about and processing correctly. Effectively TANKS are able to lift objects because when they are lifting the objects they already are calculating its position, shape, etc etc and the computer can use that processed information to power the field. In short the reason that we can't do even more with these fields is that we can only do what we can trick our minds into thinking we should be able to do... Your speedster and tank are both using the same technology, but applying it in different ways. They would likely need extensive training to learn how to 'think right' to interface with the devices; and each was trained in using them in different manners. They both would likely receive similar protection from blunt force trauma because they have an awareness of their body and their minds can project an *absorb the energy from that punch quick* thought. However, bullets are so small and fast that the brain does not have time to process them, and so the computer can't use the field to absorb or redirect their kinetic energy. [Answer] If I understand correctly, you want a new physics, not new power explanations. So, I'll avoid all physic/telekinesis that aren't really explained by physics. That means that we have to stop thinking about super heroes and think about structures. If physics allows for a superhero to life a massive object without transferring the force to the ground below him... it must be possible to build some sort of structure that does the same. Also changing the laws of physics in a particular place but not in the rest of the universe aren’t allowed either, we need a new physics that allows for superpowers but all other phenomena still works... from the stars to live, it all appears to be the same as in our world. It is time to create a new particle! --- ## The superpower particle It works like this: when an electron interacts with a superpower particle, they merge into a new particle that interacts with the nucleus the same way that electron does… but has an additional “superpower” charge. Let’s call that particle “power electron”. We are used to think that the boulder transfers its weight to the superhuman and the superhuman to the ground, but in reality the force is transferred molecule to molecule causing heat and deformation – if not rupture – along the way. When the electrons of the molecules come close they exchange virtual photons that push the electrons back (they repel※). they are both pushed back with equivalent force as per Newton’s third law of motion. We don’t want that! We want the power electron to experience no acceleration while the electron moves back. ※: the electrons absorb the photons; this causes them to have more energy moving (become more excited) them to a higher orbital (heating the molecule). Now the electrons are further away from the nuclei and closed together, but they can’t share space… so, they either find a shared orbital (creating a bond) or increase the distance between the molecules (pushing them apart, I suspect this is Lorentz force, but that’s at the edge of my knowledge). If they didn’t create a bond the electrons are no longer in equilibrium and they will spontaneously release a photon and fallback to their previous orbital. And that’s how heat agitates the molecules, but we are not talking about that. The mechanism I propose for that is as follows: if photons of the right frequency interact with the power electron it will absorb the photon, release the superpower particle, and that will quickly decay into a photon equivalent to the one that entered and probably another photon or a neutrino (not sure which works better). When electron and the power electron exchange of virtual photons, they trigger the release of the “superpower” particle effectively negating the effect of the photon on the power electron and sending it back to the original electron. After the interaction the power electron has been dissociated and a regular electron is left in its place. In practice the molecule with power electron behaves as if it had more inertia but not more mass… We are hacking relativity: Running at near sonic speed towards a metal slug is not the same as a metal slug moving at near sonic speed towards you… if you have superpower particles. Also inertial mass and gravitational mass are no longer indistinguishable… if you have superpower particles. --- Now, the superhero must be charged with superpower particles that would be used as needed. The more superpower particles the greater the feats the superhero can do. Yet, the superhero needs to replenish his superpower particles… This comes to the problem of how you generate superpower particles. Usually I would say that you need them to be a result of phenomena too energetic as to have been discovered by humans with current technology… But you can always go with the trope of the superhero with powers from radiation and say that these particles can be created by already known technology such as atomic bombs or particle accelerators, just not in large enough quantities… but then someday they were experimenting with some new equipment and there was an accident and you have your next speedster or tank! These need a mutation that allows for the generation of superpower particles in their bodies. I would probably suggest the interaction of a free superpower particle with photons may cause the photon to turn into another superpower particle of equivalent energy. So, as long as the superpower particles don’t run down to nil, they can multiplicity in some organelle in the mutated cells – something similar to the mitochondria. There may be a prophecy of a child born with a high number of mutated mitochondria who will bring equilibrium to the superpowers… but I digress… Aside from the superheroes form the atomic age, we should consider that if superpower particles can be created by such machinery, they are created in the sun too! Now you can have your next solar deity! This one of course replenishes his powers from the sun. He may be vulnerable to light of the particular frequency that causes his superpower particles to dissociate and decay… maybe generated by some green glowing mineral? --- Does that mean that watching directly into the sun will give you a power trip? Well, you may become Daredevil :v – The hazards of radiations are still there, and the dosage of superpower particles from the sun may just not provide enough for any practical superpower in the human timespan. With perhaps the exception of some mutation (maybe in the X chromosome?) that allows you to multiply the superpower particles from the sun to usable levels. But superpower materials could be viable. You just consider a decent sized monolith left untouched for millennia; it probably has accumulated a considerable amount of super power particles. Now you can have your superhero from the Egyptian Pyramids or the Stonehenge. Also, if it is possible to accidentally create machines that generate large amounts of superpower particles, it is also possible to do it intentionally. You may inject some serum in the bloodstream of a patient that includes some retro-virus that mutates him to multiply superpower particles and then bath him with the particles using a special capsule… Or you can use it to empower materials, perhaps for giant combat robots, or if miniaturization allows, create a small reactor to power an exo-suit. --- ## Power differentiation If all superpowers come from the abundance of superpower particles… why are there so many different super power sets? Simple: they don’t have the same distribution in the body. For example if they concentrate in the bones, then the bones are super! Super skin for invulnerability, super muscles for super strength, and so on… No, I don’t think superpower particles in the brain will give you super intelligence (I think it would make new neural connections harder to form)... In fact, I think the presence of superpower particles would temporarily increase the electric impedance of the material. You could get away with saying that it allows to build up electricity and then release as a spark. And I don’t see how you can explain powers such as shapeshifting, or invisibility with this. [Answer] Ok, I really like the other answers, particularly the one by dsollen - but here is an alternative. A way is discovered to modify the rules of the universe, you actually have a generator of some sort that taps into your body and when activated starts altering fundamental constants. The effect goes through your body and then radiates out from it, with decreasing intensity. Some of the fields are able to extend out along other solid objects you touch. The fields themselves are generated by some unique breakthrough, you can insert any suitably intense energy force but fusion or matter-antimatter reactions should be sufficient. The key thing is though the bioelectrical field of a living being is needed to control and contain the force. The implants can be inserted into animals, and are used for electricity generation and suchlike in that way. Far more interesting though are the military, police, criminal and vigilantes who beg/borrow/steal/build/etc their own implants and fit them to themselves. These implants themselves are tied to the individual and so some are easier for some people to use than others. Additionally running multiple implants at once becomes exponentially more difficult, so while 1% of the population could theoretically use the implants 1 in 10 of them can use 2, 1 in 100 can use 3, 1 in 1000 can use 4, etc. But what about the super-powers? Here are some examples (some hand-waving will be needed to explain how the human body manages to keep working in some of these): Superfast is just that - you modify time around you. For your purposes you are moving and breathing at your usual rate. The field extends about an inch from your body with gradually decreasing effect and can be extended out to other objects with an effort. This allows you to catch bullets, wear clothing, etc. There are no problems with acceleration or similar from your perspective, although you will still exert large forces onto the ground below you. Supertough again is the same, a field that extends only to your skin. It allows you to massively increase the inertia of everything inside it without increasing gravity. As a result blows or even large vehicles will bounce off you. Going the other way you can jump and increase your inertia as you jump to allow massive leaps. Supertough part 2 - increase the molecular bonding force of you or an object you are toughing, strengthening it into it's current shape. Flying - modifying gravity. Again potentially able to extend to other objects to allow them to fly too. I'm sure you can come up with further effects along these lines but really just playing with material strength, inertia and gravity already lets you do most super-powers. [Answer] As long as your requirements are not directly conflicting - of course you can find such a set of laws. I mean, not you. You certainly not. But a team of scientists could, in a large amount of time. But does this add anything to your story? Nope. Unless your target audience consists of natural scientists and your story *is* the physical model. For some ideas about hand waving it away, see the other answers. [Answer] I feel I have to bring this speculation of mine up. Speed-force, other-dimensional based factors aside, there's this peeve that I can't quite put aside. Isn't it impossible for bipedaled humanoids with human sized feet to even reach certain speeds where your skin peels off, your eyes are filled with boiling tears, etc. Purely by guessing, before all that, shouldn't the traction be unable to handle the speed of their legs and they end up sprawling like how you try to run on a slippery surface? Like I said, my science sucks, so I'm just speculating here. Also, putting in some racecar physics. We know that cars that launch too hard, too fast, end up burning rubber more than moving. Could the same thing happen to speedsters as well? And, still, following racecar physics, what if they did a soft launch, set off slower, but still with traction, and gradually accelerated to top speed? And even so, at say, a speed like 300mph for instance, would that previous problem of human feet not gaining enough traction come back to bite them again at that point? ]
[Question] [ I had an idea to make cockatrices "realistic" (as in make a bit more sense) for what ever reason the noble cockatrice has evolved to use other species eggs for its own. It does this by "sitting" on usually a chickens egg. When it does this it inserts it's own embryo into the egg. The cockatrice embryo proceeds to eat the chicken embryo and uses the nutrients in the egg to gestate. Once it gestates the cockatrice would scamper away into the wilds. Would a parasitic embryo like this work? Could a cockatrice replace a chicken's embryo with its own? [Answer] The tachinid flies have a similar mechanism when parasitising butterfly eggs: > > Illustrative genera include: Exorista, Voria, and Plagia. Many Tachinid eggs hatch quickly, having partly developed inside the mother's uterus, which is long and often coiled for retaining developing eggs. However, it is suggested that the primitive state probably is to stick unembryonated eggs to the surface of the host.[7] > > > From Wikipedia's article on Tachynidae <https://en.m.wikipedia.org/wiki/Tachinidae> Despite the distant common origins of flies and butterflies, the parasite feeds well off the egg content of the host butterfly. [Answer] I'm by no means *sure* of this, biology is not my wheelhouse, but I would think that the most likely "solution" in this case is that the Cockatrice reproduces by introducing a live-born predatory infant into the eggs of prey species. This tiny creature then burrows into the shell, attaches itself to the inside to seal the egg and halt evaporation and then simply kills and eats the chicken embryo and grows inside the shell using it as protective camouflage almost like a hermit crab until it has developed sufficiently to fend for itself. [Answer] Cockatrice is hatched from a **cock egg**, incubated by a **toad**. Now, "cock egg" could mean one of two things: 1. Egg actually laid by a rooster (male) 2. Malformed egg Neither allows possibility of cockatrice using a regular egg that would hatch a chicken if not disrupted. Both of those mean that cockatrice has to affect the bird before the egg is laid. In fact, it doesn't even have to be an actual egg, it merely has to be something that people can mistake for an egg. A parasitic cockatrice could develop in a living chicken, and then leave it in a form of a spore. The spore is something that resembles an egg. If it leaves the chicken through cloaca, it would be almost impossible to tell if it's excreted or laid - hence the rooster part. The toad part is harder to make up an airtight explanation for. A spore could be activated by a toad (which is lured by mimicking it's pheromones), then "hatches" and the toad is young cockatrice's first kill. ]
[Question] [ I'm developing a tree that has a peculiar fruit. Instead of having water in said fruit, there is nothing but sugar. The tree pumps sugar into a hollow orb which slowly "bakes," caramelizing into an amber shell of stained-glass sugar. This caramel shell fruit contains tiny seeds. What's more, to protect this fruit from dissolving or getting soft or tacky, the tree coats it with a super thin layer of waterproof, edible, tasteless wax. Sometimes, though, when the fruit falls and isn't eaten/smashed, it explodes violently, throwing shards of sugar-glass through the air, as it impacts with the ground (or after lying there for a while. ## Info The reason for the explosion is because the same heat that the tree generates for caramelizing the sugar into a single shell is sometimes expelled in waves through the tree roots because the tree needs to cool down. The now cool "fruit" suddenly gets a blast of intense, fiery heat, causing it to explode (hence, "sugar-bomb"). ## Question How would the tree * catalyze the heat and expel it (Edit: to clarify, expel it through its roots) * the tree generate that level of heat? (I already made the tree have black leaves for maximum heat/sun absorption: anything else the tree could do?) --- In accordance with [this meta post](https://worldbuilding.meta.stackexchange.com/questions/106/should-our-default-position-be-that-answers-should-be-science-logic-based-rath), please do not use magic as an answer. Try not to use "it's handwavium/impossible/magic" answers. I've set my premise (caramelized sugar fruit, ignoring water/uselessness). --- Thank you to all in the [Sandbox](https://worldbuilding.meta.stackexchange.com/questions/6168/sandbox-for-proposed-questions) who helped me develop this question. [Answer] Imagine if the tree had a symbiotic relationship with yeast. A developing fruit would have a rind with a semipermeable membrane that performs reverse osmosis on fermenting sugar water within the rind. The alcohol content in the outer chamber of the rind would rise as the fruit developed eventually becoming highly flammable. Eventually, an outer transparent skin on the rind would develop fluid blisters that would act like magnifying glasses focusing sunlight onto the highly flammable alcohol layer. When the developing fruit finally bursts into flame, the outer rind would burn off forming a caramelized shell around the sugar center. After the mature fruit falls yeast in the fruit's stem would kickstart fermentation in the core of the fruit (separate from the flesh of the fruit...which is of course pure sugar). Alcohol would accumulate in the core in a similar fashion to the rind, but the heat generated by the fermentation process would accumulate in the highly insulated fruit and could eventually result in a nice ethanol explosion. Now while the tree itself has evolved to be fairly flame resistant to catching on fire, the periodic exposure to brief bursts of extreme heat from its fruit means the tree needs a way to shunt excess heat in its leaves and branches for brief periods of time to avoid bursting into an alcohol-fueled inferno when its fruit ripens. To facilitate this the tree has heat sensitive cells that cause the capillaries in the roots to contract pushing cool pure water from underground up into the leaves and causing the fermented sap in the leaves to be forced back down the tree to the outer skin of the roots and into surface nodules in the root system. These root nodules further cool the tree via evaporative cooling as the alcohol in the sap evaporates through the skin of the nodules. While the rapid cooling mechanism employed by the root system does work to quickly cool the tree the alcohol vapors released by the root nodules means that occasionally a spark from a ripening fruit will drop into the vapor cloud surrounding the roots catching the vapors on fire. This has been known to light the stems of fallen fruit in the vicinity of the roots which works like a wick causing the alcohol reservoir in the fruit's core to light on fire and explode. [Answer] Caramelization of fructose requires A minimum temperature of 110°C and a perfectly uniform distribution of the heat, so the fruit would bake itself the moment the process started. Even worse, if it started baking from the outside, for thermal energy would be lost before it started cooking the sugar lump inside. You'd have a fruit-flambé with a barely caramelized lump inside. And the tree should be made of asbestos: Imagine all those hanging fruits taking fire one after the other, yikes! Not to mention that this GMO tree would have the less efficient way to spread its seeds: the idea of the fruit falling, rotting rapidly or being devoured is that one way or the other the tree reproduces efficiently. Once the seeds are trapped in the fructose crystals, it would take days of rain before they can go to Earth -o well, not to mention they'd be nicely cooked in the caramelization process. And for sure, they couldn't be eaten by birds: caramel is tough and comes in shards, it would be like eating glass. EDIT: The answer is: This tree cannot generate the necessary heat, unless it is not a tree at all, made of non-organic, fireproof material. Because a tree doesn't just generate enough heat as to burn itself. Even using the most advanced genetical engineering, the resulting organism would be something that only looks like a tree: it should have conduits of highly reactive incendiary chemicals that, in contact with the sugar, start melting it and cook it. Then the tree should 'know' that the optimal temperature is reached and at that point the fruit expels the excess heat until its core is a mass of solid caramel. A core that, by the way, should be made of a thick layer of hardwood or, again, the fruit would cook during caramelization. but if we have a layer so tough around the core, it will not 'explode' by falling or by any other means, unless it is made of explosive material. And speaking of heat dissipation, at this point we should think of another kind of fruit entirely: It should look like a pinecone grenade with microvents between its 'leaves', so to dissipate the heat during the caramelization of the core. But the problem of the hard-protected core would remain [Answer] Ideas: 1: Your sugar bombs as proposed have a hard shell of caramel. That entails heat at the edge of what biological systems can produce which makes it tricky. **You could instead make a shell of crystalline sugar: rock candy.** Sugar will crystalize out at room temperature as the solvent (water) evaporates. Crystals can form on fruit that is damaged by bugs but there is no reason your fruit could not do this by itself. That gives you the hard shell without the heat. 2: **Your sugar bombs heat up via [spontaneous combustion](https://en.wikipedia.org/wiki/Spontaneous_combustion).** You can find reports of stored sugar and molasses spontaneously combusting. As regards carbohydrates usually one reads about hay piles - bacterial fermentation starts things and then the material gets to a heat in which the reaction is self sustaining. So too your sugar bombs - they do not receive heat but rather generate internal heat by oxidation / fermentation of the sugar within the fruit. 3: **They want to blow up.** Having something in a hard shell getting hotter and hotter is a fine recipe for an explosion. If nothing eats the fruit (to later poop out the seeds), the fruit does not want to be eaten by ants which do nothing for seed dispersal. Having it explode violently is a fine way to spread seeds at least out of the immediate vicinity of the parent tree. [Answer] Overall, I think your frag-grenade tree concept isn’t impossible, but it needs a different mechanism for heat. **Heat** Sugar starts to caramelise at perhaps 110°C, but to reach a hard consistency, you need to go higher - a quick google for recipes gives 160°C for “hard crack” caramel. In practice, due to how heat is lost from the pod, some parts will need to be significantly above this temperature. Obviously this is pretty bad for any seeds inside. Worse still, Wood starts to char at 120°C, and it’s actually it’s above the flashpoint for decayed Wood (150°C), and nearing the flash point for fresh Wood (190-260°C, depending on the Wood). So you can’t use heat to caramelise it, or your tree is very likely to spontaneously combust. Unless you make this part of the tree’s lifecycle, that it occasionally bears fruit and burns down, leaving just the roots to regrow from? You’ve still got to deal with the seed surviving the temperature though. **Heat waves in roots** Isn’t going to happen. Due to the insulation of the ground, your roots would need to be extremely hot for a “heat wave” to reach the surface. It’s likely this would cause the soil to burn (soil can and does burn, e.g. due to fires in mines). Even if your tree is made of asbestos you need an alternative mechanism here. I’d suggest that your caramel pods have some kind of internal stress, or perhaps a pressure build up inside, which can cause the explosion you’re looking for. This would be a lot more plausible. If you want them to *sometimes* explode, we can rely on caramelization being a tricky beast at the best of times. Many factors affect how crystals grow and their size, so it’s entirely possible for some pods to be weaker, some to vent safely and slowly, etc. **Catalytic caramelization** So if not heat, try a catalyst? A quick Google shows catalysts can be used to assist caramelization, so it’s not ridiculous that your tree could produce a catalyst which allowed caramelization at a survivable temperature. So you can create your caramel without igniting your tree. **Propagation** Whilst some animals might not want to eat caramel, others would, and the sharp corners would be the first bit to go once they’re exposed to damp air. And ants would absolutely love it! It would also protect the seeds inside until the caramel had dissolved, which may be preferable, since not all plants want their seeds to germinate immediately. So no issues there. [Answer] I'm surprised it hasn't been suggested, but there are plenty of chemical reactions that are violently exothermic. What you could do is have your tree synthesise two different compounds in lots of small pockets evenly distributed throughout the fruit, and when it's ripe, the walls between the pockets break down, the two compounds combine and the fruit explodes. Take a look at the internal structure of an Orange for example, where it's clearly defined into segments inside, each partitioned from the others and containing a lot of juice. This has the advantage of also detonating when the fruit hits the ground because of the shock of impact breaking the dividers. Alternately, if simply producing heat during the ripening process is your goal, making the fruit produce both chemicals and immediately allowing them to mix will produce a constant heat rather than explode. I'm no chemist, so I couldn't tell you what specific compounds would produce that kind of temperature, but I'm fairly sure it's not out of the realm of possibility! [Answer] Re The sugar bomb tree. High temperatures could be generated very quickly using an exothermic chemical reaction between two compounds. This is how [Bombardier Beetles](https://en.wikipedia.org/wiki/Bombardier_beetle/ "Bombardier Beetles") (family Carabidae) generates hot caustic repellant that builds up in a reaction chamber which is then expelled at high pressure. I kid you not! Ive been hit by them - couldnt resist touching one. ]
[Question] [ In SpartaNova, there is a flat base income tax rate of 70%. For each year of military service that a (potential) citizen performs, his or her future tax rate is decreased by 10% if the service occurs during peace time and by 15% during wartime if in a non-combat role, and 25% during wartime if in active front-line combat, down to a minimum tax rate of 20%. There is a special exception for special service fighters (i.e. seal teams, and other dangerous jobs like bomb disposal teams), nuclear submariners, air force pilots and higher-level intelligence workers all of which receive an additional cut of up to 5% per year of service, down to a minimum of 10%. Service is ***voluntary*** and standard expected service is 2 years, but a serviceman can elect to serve longer if he or she so desires and is not otherwise blacklisted from the service for some reason. Veterans (a la Heinlein's Starship troopers) also receive the full right to vote (non-veteran residents only vote in local elections). There is no "family" tax rate, and the income of each spouse is taxed according to her service or lack thereof, and dependents lose their tax-dependent shield at age 17, when full 70% income tax (or military service) kicks in. It follows that most rich people would be strongly incentivized to send their children to serve in the military to diminish their future tax burden. Poor people would have the same incentive, true, but the rich would have a disproportionate amount to gain from diminishing their flat rate. **Would a society where the sons and daughters of the richest all serve (if able) be significantly different from ours?** For instance, would the nation be much more careful about declaring war or engaging in what we euphemistically call "kinetic operations"? Do more important implications of this come to mind? Yes, I am aware it would likely be an even more unequal society, but I have never mentioned what the taxes are being spent on, or what the inheritance tax rate is, so perhaps we should remain agnostic on that a little longer. [Answer] > > Would a society where the sons and daughters of the richest all serve (if able) be significantly different from ours? > > > Maybe, but this wouldn't get you there. A 70% tax rate hurts poor people more than rich people. If a poor person needs \$200 a week to pay bills (housing, food, utilities, etc.) but only makes \$500 a week, then a 70% tax leaves them without enough money to buy basic subsistence (only \$150 a week). Yes, the rich person might pay more in absolute terms, but in proportional terms, they will pay the same rate. And the thing is, that rich people have more discretionary income. That's why rich people spend their money on extra houses and private planes, because they can afford it. Someone making \$100,000 a week would still have \$30,000 a week left. Such a person remains rich even after taxes. It's also worth noting that this is an income tax, but being rich is a function of wealth. It's quite possible for someone who is rich to have no income. They can live off their wealth and pay zero tax. A poor person does not have that option. The real difference here is that it is much easier for low tax people to *become* rich. If you have two people with the same income but one has a tax of 20% while the other has a tax of 70%, one of them will find it much easier to save for the future. If you want to incent rich people more than poor people, which is how I read your question, you should use a wealth tax rather than an income tax. Note that wealth taxes can be much lower than income taxes. The equivalent of a 70% income tax would be a 7% wealth tax. Rates like 10% or 20% are huge and would allow for large reductions, down to 2% for example (rough equivalent of a 20% income tax). You also may want to consider offering certain exemptions per person. For example, the first \$10,000 of income or \$100,000 of wealth could be exempt from taxation. This would make service less of a necessity for the poor and more of an option, as it is for the rich. Note: numbers given are in magnitudes reasonable for the US. Presumably there are equivalent numbers for other societies, but the US is what I know. Note that a minimum-wage, full-time job pays \$290 a week in the US (national rate; may be higher locally). [Answer] It's clear that the government would be more wary of sending troops directly into combat, or "putting boots on the ground" where people could die. The rich are powerful. They already influence politicians (well, maybe not Bernie Sanders) through "campaign contributions" and Super PACs, giving them more money to do things that will benefit them. One thing that will benefit the rich is to have their kids come back home - alive, not in a body bag. There will absolutely be this reluctance to send in troops, but I can guarantee you that it will only apply to certain troops. As you acknowledged, even the poor will have an incentive to serve, so it seems likely that there will be many more troops and G.I.s signing up. This means that the military will have more troops than it needs (except in times of war) and can afford to hold some back. Guess which troops will be held back, and guess how many zeros are before the decimal point on their parents' annual paychecks. The rich kids will get the safer jobs1 - remote surveillance, piloting UAVs from home base, gathering intelligence via satellite, etc. Chances are good that they'll have had great education, if they go to college before serving, and will be fit to do more than grunt work. So they'll get the safe jobs, while the poor suffer and die on the front lines. What emerges from this is a segregated military, in a way. The jobs that involve no actual fighting or danger will go to the rich. They'll control remote intelligence, cyberwar, remote surveillance, and the like. They'll rise to top positions so they can command from behind, while the troops will be made of poor blokes who are literally worth nearly nothing. The rich parents put pressure on politicians to give their kids cushy jobs, and the kids soon command the military, creating an even greater class divide, and maybe resentment towards the top of the heap in the military. Alienation between the front line troops and the generals, as well as between branches of branches of service, will lead to less unification and a less effective military. --- 1 No disrespect meant to the skilled men and women who carry out these jobs today. They aren't easy, and they're necessary. I'm simply looking at it from a standpoint of the likelihood of survival. [Answer] You mention that the rich would gain disproportionately more, but in fact they would gain proportionally more. This leads to an interesting consequence of this system: your fiscal incentive to serve in the military, as a percentage of your life's earnings, is constant whether you are rich or poor. However, I would expect the rich to not just sit back idle and let the system place them into the cogworks. They would use their influence to make sure they can get the least dangerous jobs in the military and "serve their time." If we can remove the risk to one's life from the equation by using Daddy's influence to get a safe job in the military, we can approach the role as a job. In exchange for each year of your life in service, you get a 10% reduction in taxation for the rest of your life. This is a *massive* payday. **Massive!** Let's take an example of the least beneficial year: your last year. The last year, your 8th, takes you from 30% taxation to 20% taxation. Let's say that, after your service, you enter a job which pays an average of $80,000/yr when you average it over the rest of your life, including things like promotions. If you were to work until you're 65, and we [conservatively] only consider work you'd make after age 30, you will make \$2.8 million in your lifetime. Thus, the difference between 30% taxation and 20% taxation is the difference between taking home \$1.96 million and \$2.24 million. Needless to say, when given the choice to enter the civilian workforce early and earn \$80k/yr or stay in the military and earn an effective \$280k/yr, you'll find a lot of people choosing to stay in the military all 8 years. And remember, this scales proportionally, so the rich that were looking to make \$1million/yr will effectively earn \$3.5million/yr during service. Now the follow up question should be what sort of culture do you end up with where most of your youth spends 7 years in military service. That's a lot of bodies who need military work for them to do. [Answer] Compare Israel, which has near-universal military service and constant low-level combat operations. The causation is the other way round: that society has universal military service *because* it gets involved in a lot of fighting. Historically it's not unusual for high aristocracy and royals (UK royal family and others) to do military service. After all, it's a way of practicing for holding rank and establishing it over the lower ranks. One thing you should watch out for is people would game the system by working out what posting had the best tax advantages for the least actual danger at any point of time. It's great being a bomb disposal expert if you can arrange to be posted to an area with no bombs. [Answer] (Note: I'm assuming you mean a decrease in percentage points [ie 70% -> 60% -> 50%] and not an actual percentage decrease [70% -> 63% -> 56.7%].) I think that while there would be differences, it would ultimately end up pretty similar to today's society. **Differences:** The leaders of SpartaNova would probably be a bit more cautious about declaring war. It's the simple effect of knowing that your child could be on the front lines -- but we'll get more in depth on that later. Wars would probably be carefully scoped out, planned to be combat-light and occupation-heavy (statistically you're more likely to die during combat than during occupation, so in the name of "keeping the children safe"....). Military service is the economically smart option. Due to the growing class differences (more on that in a bit), there may be resentment toward the military families. **Similarities:** Gonna start with some assumptions here. 1: People like money and people like power. 2: Those who have one, the other, or both, want to keep it. 3: Parents don't want their children to die if possible. 4: In addition to only getting full voting rights through military service, you can only fully run for office with military service. Suppose there are two sets of people, those who have served and those who haven't. Over the course of a few decades, those who have served will end up significantly more wealthy than those who haven't (the simple effect of a 20+% reduction in taxes compounded over the years). Also, the power base will be veterans -- even if Assumption 4 is incorrect, veterans will be more likely to vote for other veterans, because of the brotherhood and all that. So we end up with one group that is both wealthy and powerful. By Assumption 2, they want to stay that way. How do they do that, especially when it's easy for someone to move into that group (all they have to do is serve for a few years and save money)? Well, they have to find a way to make sure their kids can stay rich and powerful. That little bonus to specific roles in the military is suddenly a big deal. If they can rig things so that their kids are getting the "good" jobs, while the common riff-raff get the "bad" jobs, that will help them even more. So we could set things up so that the wealthy families can afford specialized schools that include a focus on, for instance, military intelligence or aviation, making them more likely to get the specialized positions which lead to a better economic future for them. Alternatively, something like ROTC would be a huge draw for the wealthy families -- anything to get little Bobby a chance to get as high of a position as possible to keep him out of the line of fire. Sure, there's more risk involved in SpecOps or the Bomb Squad, but the bonus tax reduction can save a hell of a lot over a lifetime. And realistically, if they're already rich and powerful, they can probably swing it so that Bobby gets put in Intelligence, or on a submarine somewhere. Leave the Bomb Squad for the poor, think of it as a lottery to get elevated to a higher caste. The issue with that is that it's the poorer families who are going to be on the front lines, for the most part. So going back to the earlier issue of declaring war with your kid on the front lines... Maybe not so much. The children of the rich and powerful are at less risk overall, leading to even more of a class divide - the majority of the casualties will be poor people, so enlisting is less likely to give you an advantage than going through . There's also a high possibility of behind-the-scenes networking. "Oh, you're John Smith's kid? We've been buddies ever since Basic, I can definitely find you a place in [a "good job"]." So all in all, it looks pretty similar to today's society, with a few minor differences, namely an even bigger class divide and the possibility of resentment toward the military. [Answer] I imagine a society where most people join the army as soon as they leave school, remain for 5 years and then move onto their actual desired profession, which would result in a very youthful army (17-21 year olds), and a very small tax base into the future. Presumably you get paid while you're in the army, so I wouldn't see too much of a problem with career soldiers - some of them may like it and stay on just as they do in real life. [Answer] *Would a society where the sons and daughters of the richest all serve (if able) be significantly different from ours?* **Probably.** Service is not mandatory, but almost every one do some time in the army. I also suppose that the technology level is close to ours (or above). *The question is why would a society put such high price on "staying out of trouble"* This could come from either a warrior culture or from a country that has a huge need of soldiers. If it's a cultural thing, the loss of children will be either seen as a reason for revenge or as a proof of failure, maybe even from the whole bloodline. As it is a cultural bias, people will take the loss as they are and interpret them as they see fit. If the main reason for this choice comes from territorial expansionist politic (Think roman empire). With modern media there will be a lot of propaganda around life loss. But the children of the powerful might be somewhat protected, with special "useless" units reserved for them. This makes for an unstable and probably repressive system as the rumors and conspiration theory might propagate out of control. If it's a modern, western, country with dangerous neighbour/beasts, the problem has to be temporary. Our countries and ethics are not really build for sustained period of war and continuous loss of life. This is a case where your country would be the most like ours, then turn slowly to one of the first two solutions to sustain the moral drain, either evolving it's own culture or turn to totalitarism to cope with the problem. I forgot another possibility : You don't have much wars and conflict, so you keep a limited army. The thing is that the only one to really get the places, and the tax exemptions, are the rich kids. Of course, anyone can apply, and every one know someone who know someone whose brother has had a place. Plus you give a wide media coverage to the streets kids. But if anyone look at the real numbers, access to the military is a privilege. Though this is not exactly "spartan". [Answer] It all depends on what life is like when taxed at 70%. If it is like some European countries, where taxes are high but you get free health care, free university, etc., then many people will be content with their position in life and there is no real incentive to join the military. If that 70% tax doesn't get you much when it comes to government services, then you are on the wrong side of the Laffer curve, and there is no incentive for anyone to work. There is no incentive to earn any money. Not legally, anyway. If you effectively get nothing for your 70%, then it's far more of an incentive to fight the government than it is to join it. Plenty of governments have been toppled by imposing too many taxes upon the people. The government would be smart not to incentivize military service in this case, because you don't want the revolutionaries to have military training. [Answer] As an initial premise, a 70% effective tax rate is not particularly unreasonable. From 1936 through 1983, the effective tax rate was at (or significantly higher - approaching 90% at times) 70% for the highest incomes. If service were sufficiently dangerous or burdensome, this tax rate would likely be acceptable for many of the richest compared to the risk of injury or death. With a minimum service period of two years, and no constraints on when an individual could enlist, the richest would likely postpone joining the military until periods of peace, and enjoy the benefits for the rest of their lives. If possible, individuals would likely enlist and serve when they are young and have low earning potential in the least dangerous and least difficult positions possible. In all likelihood, this system would be established as a part of, or simultaneous with, the individual's higher education. If not, there would be a marginal benefit to employment figures as military service would likely serve as a massive 'jobs' program that keeps people out of the non-military workforce. Overall, however, if you could receive the maximum benefit possible by serving five years in a safe peacetime role, I think most people would choose to serve to reduce their future tax burden. Many countries already require some sort of compulsory service for 2-4 years without massive changes in their society, so I doubt that there would be little impact across society beyond much lower tax revenue (which, notably, would greatly impact the ability of the government to support a military that consists of the majority of the 17-25 demographic). ]
[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/919/edit). Closed 4 years ago. [Improve this question](/posts/919/edit) I'm writing a post-apocalypse story that takes place in New York, mainly the city as the survivors escape the island to the outer boroughs. Anyway, living in New York all of my life, the worse that I've seen is Hurricane Sandy. What I'm aiming for is something natural, but something that could happen at a moment's notice, hence the apocalypse. I've read some theories about global warming and the weather in general, and I've read stories like Stephen King's "The Stand" and the "Maze Runner" series by James Dashner, especially the prologue where they talk about the sun flares. So, I don't want to go supernatural like "The Stand", and also don't want to go so far into the future that I have to make up tech or language like "Maze Runner". So, what's the worst that can happen to the world, specifically New York, weather wise that would begin this apocalypse? (PS: I was aiming for New York freezing over and practically becoming the Arctic but it appears that hurricanes are more possible?) What I've read so far: <http://www.popularmechanics.com/science/environment/natural-disasters/what-happens-when-a-super-storm-strikes-new-york-6323032> <http://www.cracked.com/article_20384_the-5-major-cities-most-likely-to-be-spectacularly-destroyed.html> Thanks for all your scientific theories in advance! :-) \*\*\* UPDATE: To answer some of the comments, this story is focused on New York, but it doesn't necessarily mean that the disaster in New York was just a sole event versus being a chain of events caused by something world-wide. As a survivor in NY though, I'd assume that the least of your concerns or even knowledge due to being cut off from society is what's going on with the rest of the state, country, or world itself. And when I say "escape" I guess what I mean is leaving the island in search of other survivors and finding a stable and safe place to be versus the city. Since Manhattan is an island, and if the disaster is related to the ocean (hypothetically), I'd think the inner boroughs would be safer than the island so to me, these were the logical places that survivors would aim for if the city is screwed. Anyway, looking at the answers now. :-) [Answer] For a coastal city like New York the obvious choice is a Tsunami. These can be triggered a number of ways (Earthquake, Volcanic explosion, Landslip, Meteor strike in ocean) and even a high tech first world country would only get a few hours warning depending on where the trigger event happens. Read up on Krakatoa for the volcano cause, Japan recently had an earthquake-caused one. You can look at La Palma in the Canary Islands for the Landslide trigger although there is some debate as to just how large the Tsunami would be. **Krakatoa:** This would involve a new hot-spot appearing in the crust and a volcano forming off the coast of New York (which would take several years at least). The side of that volcano would then collapse letting sea-water in. The resulting explosion and tsunami could then be devastating and that final act would happen very quickly. <http://en.wikipedia.org/wiki/1883_eruption_of_Krakatoa#Final_explosive_eruption> > > The pressure wave generated by the colossal fourth and final explosion radiated out from Krakatoa at 1,086 km/h (675 mph).It was so powerful that it ruptured the eardrums of sailors on ships in the Sunda Strait, and caused a spike of more than 2½ inches of mercury (ca 85 hPa) in pressure gauges attached to gasometers in the Batavia gasworks, sending them off the scale. The pressure wave radiated across the globe and was recorded on barographs all over the world, which continued to register it up to 5 days after the explosion. Barographic recordings show that the shock wave from the final explosion reverberated around the globe 7 times in total. Ash was propelled to an estimated height of 80 km. > > > **Earthquake:** Even in non-geologically active areas earthquakes can still occur, although they are rarer. In order to generate a large tsunami a moderately sized earthquake would normally be combined with an underwater landslip as happened in Japan. <http://www.nbcnews.com/science/environment/paris-sized-landslide-may-have-doubled-size-japanese-tsunami-study-n216941> > > They later found evidence on the seafloor of a landslide with a horizontal footprint about the size of Paris, measuring 40 kilometers by 20 kilometers (25 miles by 12.4 miles), and 2 kilometers (1.2 miles) thick. The landslide created a focused tsunami wave that, when combined with the power of the earthquake, reached epic proportions, he said. > > > **Landslide:** Some islands, particularly volcanic ones, have vast amounts of rock and earth in potentially unstable positions. A collapse in that island that happened fast enough and in the right direction could potentially trigger enormous tsunamis. <http://en.wikipedia.org/wiki/Megatsunami#Canary_Islands> > > However, the western half of the volcano has an approximate volume of 500 cubic kilometres (120 cu mi) and an estimated mass of 1.5 trillion metric tons (1.7×1012 short tons). If it were to catastrophically slide into the ocean, it could generate a wave with an initial height of about 1,000 metres (3,300 ft) at the island, and a likely height of around 50 metres (164 ft) at the Caribbean and the Eastern North American seaboard when it runs ashore eight or more hours later. > > > **Meteor:** A meteor impact into water would in many ways be more destructive than one into land. Huge waves would radiate out in all directions causing the coast to be battered by at least one and possibly multiple (as the waves bounce around) tsunamis. <http://news.ucsc.edu/2003/05/355.html> > > A computer simulation of an asteroid impact tsunami developed by scientists at the University of California, Santa Cruz, shows waves as high as 400 feet sweeping onto the Atlantic Coast of the United States. > > > **Man Made: (See [Sheraff's answer](https://worldbuilding.stackexchange.com/a/934/90) for more details)** If too much were extracted from the wrong parts of continental shelves then that could in itself trigger the underwater landslide that then triggers the Tsunami. For example Methane Hydrate extraction in the wrong places could cause just this scenario to happen. <http://www.dlr.de/blogs/en/desktopdefault.aspx/tabid-6192/10184_read-189/> > > If methane hydrates were ever extracted from continental shelves without appropriate precautionary measures being taken, the disaster scenario painted by Schätzing in ‘The Swarm’ could occur: without methane hydrates, the shelves on the coasts could become unstable, gigantic landmasses could start to slip and that in turn could trigger tsunamis. Experts are taking these risks seriously and are only experimenting on the extraction of methane hydrates in flat storage locations far from continental shelves. > > > [Answer] **Plague** Diseases are adapting to [modern day medicines](http://www.who.int/mediacentre/factsheets/fs194/en/) at a [frightening rate](http://www.nature.com/scitable/topicpage/antibiotic-resistance-mutation-rates-and-mrsa-28360). New York is a very densely populated area, there is only limited healthcare available. Consider the number of people the average citizen meets in a day, the number of people to use the same taxi, the number of people crammed in a subway car. If a disease which was immune to a couple of the standard antibiotics mutated inside one of the 8,400,000 people living there it would spread incredibly rapidly. There are only hospital beds for 59,000 of them [in the state](http://www.ahd.com/state_statistics.html). * Healthcare would crumble, not only from primary infections but all of the other diseases which also need treating * Infrastructure would shut down because there aren't enough people to drive the subway, man the banks/shops/restaurants, work in the hospitals * People wouldn't be able to work, homes would be repossessed. Bad debt! * Quarantine zones would need to be established, this will concentrate the disease in the city and limit food, medicine, fuel and other resources required. Now scale it up * The USA would lose a massive economical powerhouse (even if the disease is beaten the damage to the economy would be massive) * I've already mentioned bad debt, suddenly banks have mortgages which aren't being paid. This causes the same sort of problems we saw in 2008 (and are still recovering from 6 years later). * What impacts the US impacts the word, damage to stock markets, pensions and investment firms across the world In short, crowded populations help diseases spread and are more dependent on imports from the surrounding area. It would be [The Black Death](http://en.wikipedia.org/wiki/Black_Death) all over again (interestingly the first occourances of multi drug resistant Yersinia pestis have now [been seen in Madagascar](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1610074/)). Scared yet? [Answer] **Methane hydrates destabilization** (either from extraction or from a local or global, temporary or long-term warming of the ocean around it) could cause a **landslide** around the very **unstable volcano** Cumbre Vieja, Canary Islands, triggering a minor **earthquake** that would result (through a chain of event detailed below) in a **tsunami** 50 meter high wiping out New York at **a thousand kilometres per hour**. This is in my opinion, the most likely yet worst thing that could happen nowadays, at any time, without any warning, and with absolutely no way of stopping it. > > In 1949 the sleepy old dog Cumbre Vieja sprang into action with a > bang. The eruption came from one of its craters, at the top of the San > Juan volcano. It opened up a fault. It's hard to spot with the naked > eye, but it runs for kilometres along the western flank of the island, > just below where we're standing. It's possible that the rock at the > heart of La Palma has been fissured. At the time, a section of the > Cumbre Vieja ridge slipped four metres downwards into the ocean. [We]'ve > been monitoring the area for the past few years. It's highly likely > that the next eruption will cause the western flank to break off > entirely, owing to the unusually large amount of groundwater trapped > within the rock. As soon as a new burst of hot magma enters the > volcanic vent, the water will expand and evaporate in an instant. The > resulting pressure could easily blast the western flank into the > water. It's already been destabilised, and the eastern and southern > flanks are pushing against it. Five hundred or so cubic kilometres of > rock would collapse into the ocean. > > > The consequences are too dire to imagine. Volcanic islands have a > tendency to get steeper with age. Eventually a section breaks off. The > authorities on La Palma don't want to face the truth. It's not a > question of if it will happen, it's a question of when. In a hundred > years? A thousand? The only thing we can't be sure of is the timing. > The volcanoes here don't give much warning. > > > The mass of rock would displace vast quantities of water. A dome would > form on the surface of the ocean. According to our estimates, we'd be > looking at a speed of impact of three hundred and fifty kilometres per > hour. The fallen debris would extend sixty kilometres over the seabed, > stopping water flowing back over the landslide, and creating an air > cavity that would displace far more water than the volume of the rock. > There's some debate about what happens next, but none of the scenarios > are especially comforting. The landslide would create a mega-wave off > the coast of La Palma, with a probable height of six to nine hundred > metres. The wave would set off across the Atlantic at a thousand > kilometres per hour. Unlike earthquakes, landslides and slope failures > are point events, which means the wave's energy dissipates as it > radiates across the ocean. The further it travels from its source, the > flatter it becomes. > > > The Canary Islands would be wiped out in a flash, then an hour later, > a hundred-metre-high tsunami would wash over the northwest African > coast. Six > to eight hours after the eruption, a fifty-metre wave would sweep over > the Caribbean, laying waste to the Antilles and flooding the east > coast of America from New York to Miami. Soon afterwards the wave > would hit Brazil with similar force. Smaller waves would travel as far > as Spain, Portugal and the British Isles. The consequences would he > devastating, even in central Europe. The European economy would > collapse. > > > [This fifty meter wave] would be enough to flatten New York. The > impact of the wave would release more energy than the United States > uses in a year. It doesn't matter how tall a building is – it's the > base that takes the force of the tsunami. The rest of the building > collapses, regardless of how many storeys there are. > > > There are two ways of destabilising the western flank of the island: > either Cumbre Vieja erupts, or there's an underwater avalanche. The > rock will sink into the depths, and that in turn will prompt a minor > earthquake and destabilise the Cumbre ridge. The earthquake might even > trigger an eruption, but in any event the western flank will detach. > > > from *The Swarm* by Frank Schatzing [Answer] For any particular calamity, there are ways around it (in particular prepared scenarios how to deal with it). In my opinion, when things start looking really ugly, is when multiple things hit at once. For that I recommend for your book besides the main damage-dealer, something else to severely hit morale. In particular, the survival depends very much on spirit, for example in the case of sea-survivors vomiting (from being sea-sick) in rafts has detrimental effects because it very much worsens the mood, and survival rates drop then unexpectedly fast, from weeks to mere days or hours. Some examples: * A calamity: Tsunami that floods the whole area but leaves most structures intact, there is not enough potable water, disease start to spread, but things are still manageable. Then, a secondary shock (perhaps which makes the first a foreshock) that crumbles some symbolic building or kills some charismatic leader. * A nightmare with a Philip K. Dick like twist: A potential terrorist attack that spreads panic, among others causing crime to go rampant, then military steps in with brutal force, however, it is very hard to say who is a bad guy, and who is not. Unexpectedly a nuke goes off, people all around work very hard to get others to safety and treated by medics. Then we learn (e.g. a scene with confused doctors) that the real terrorist attack was a virus, and the nuke was to save the rest of the area/coast/country which is now doomed because of our heroic effort. (Of course it's up to you, whether the virus is natural enough for you). * We did this to ourselves: you don't need any special technology, to imagine that one could overextend the subway and road network underneath the city (e.g. several levels deep). In case of hurried, underfunded development, a [subsidence](http://en.wikipedia.org/wiki/Subsidence) could easily happen, perhaps related to even some minor earthquake or a groundwater reservoir (e.g. in your story the ground below Manhattan might not be a solid bedrock, the true geological data could have been altered for some greedy people to get lots of money). Pair that up with unusual drought and you have a tragedy ready. Then, as the situation is getting worse (fallen buildings, lots of casualties, crowded hospitals, lack of potable water), people learn that the medical treatment they received force them to rely on costly medication for next few months, which makes the crime rate go up and up at which point the government declares martial law and (by mistake or panic or overzealous officer) Manhattan is sealed from the coast. That generates even more panic, power struggle at the top creates a delay enough that the decision cannot be safely reversed, hell ensues. I hope this helps ;-) [Answer] Climate change is probably the most dangerous threat to coastal cities, not just New York. The problem with New York is that it's close to the sea and many of the infrastructures are close to sea level. As you mentioned, Hurricane Sandy made huge damage, partly because New York is not equipped or built to deal with that kind of problem. The geographic position of the city is really not helping here since Manhattan is surrounded by water and it's pretty flat. Also, an urbanized coast means no natural protection form the winds/waves. A hotter planet means more energy and that energy is released in different form, including more frequent and more powerful hurricanes. They form closer to the poles. New York is likely to expect more powerful storms in the near future. It will not destroy the city but it will make life more difficult and will cost billions to clean up. Typhoon Haiyan/Yoland that devastated the Philippines was one the strongest hurricane ever recorded. The most powerful wind at more than 200 km per hour. Buildings in NYC are not built to resist powerful winds. Tall structures must already deal with strong winds high above the ground but if you add an hurricane, it might cause some serious damage. The rising of the sea is not a very big problem because it's gradual. Even if we expect the worst, (1 meter during the next 100 years) it's manageable. More water mean more damage during the storm but New York can build a dike to lessen the damages. But on the long term, if we don't change our gas emission it is highly probable that cities like New York will be flooded under several meters of water making life very hard for the people there. Eventually, the buildings will collapse because of the non-stop water flow and the corrosion from the sea water. [Answer] A [solar](http://en.wikipedia.org/wiki/Solar_storm_of_1859) [storm](http://science.howstuffworks.com/solar-flare-electronics2.htm) probably isn't the worst thing that could happen, since it most likely wouldn't be powerful enough to destroy individual electronics, but it could wipe out our power/communication grids for a few weeks/months. [Answer] The absolute worst disaster that could hit New York City: **Rogue neutron star.** Any "worse" disaster would be easier to see coming (like a rogue black hole or something.) Neutron stars are pretty much non-reactive and don't give out much sign of their presence, and are effectively unstoppable. Any "lesser" disaster or more localized disaster (Tsunamis, Earthquakes, Supervolcano eruption, etc.) would be much more survivable. Many Skyscrapers are earthquake and Tsunami resistant, a sudden volcano would have an avoidable epicenter, and any disaster that didn't affect the world as a whole would leave many of external response teams to come help out. Granted, the rest of the world is pretty much toast too. But New York is part of the world. [National Geographic did a pretty interesting documentary called 'Evacuate Earth' of what such a disaster would probably shape up like.](https://www.youtube.com/watch?v=FWUgEgq2jnU) [Answer] I'm not affiliated in any way with the author and it's been a number of years since I read the book but IIRC there's a chapter in this book that lays out exactly what would become of NYC in the absence of humanity. <http://www.worldwithoutus.com/index2.html> From the [WP article on the book](http://en.wikipedia.org/wiki/The_World_Without_Us): > > He explains that sewers would clog, underground streams would flood > subway corridors, and soils under roads would erode and cave in. From > interviews with members of the Wildlife Conservation Society and the > New York Botanical Gardens Weisman predicts that native vegetation > would return, spreading from parks and out-surviving invasive species. > Without humans to provide food and warmth, rats and cockroaches would > die off. > > > (As pointed out by @bowlturner this is is probably a comment, but is too long) [Answer] Some sort of extra galactic entity like a comet or asteroid contains a previously undiscovered or theorized type of matter that has a new type of energy signature that disrupts magnetic and electrical functions. The impact significantly alters the magnetosphere and the energies of earth in such a way that any attempt to generate electricity more than a spark results in effects similar to a localized EMP. No electronics work anymore, and no new electronics can be created because of the EMP effect that results from the magnetic field created by energizing something, and the new energy type that now permeates the Earth, reacting with each other. Metallic objects all behave strangely from seeming to flow like water, to shattering into dust like a crystal reacting to certain harmonic frequencies. Literally throwing the world back into the stone age. Most of the buildings in Manhattan have been destroyed or rendered effectively unusable by this phenomena. ]
[Question] [ Set in the modern day, I was wondering about a possible scenario in which some hackers gain control of many satellites, probably including those specifically for defense purposes, in order to wreak havoc on many cities around the world. What kind of satellites are the easiest to hack, and how can the hackers use them to commit genocide worldwide? [Answer] # Trigger nuclear war Hack a military observation satellite and tell it to transmit a signal indicating a nuclear launch by a hostile power. You'll probably need to hit a few concurrently for a convincing signal. After that you just need to sit back and watch the fireworks. # Trigger Kessler Syndrome You don't need to knock them out of the sky, you just need to [knock one into another](https://en.wikipedia.org/wiki/Kessler_syndrome). I don't know if there's enough materiel in orbit for the full Kessler cascade but the theory is well known and has been for decades. Generate enough debris and the species is effectively bound to the atmosphere for decades. No satellite communication, no GPS, only basic weather forecasting, (no spy satellites). The damage is incalculable. [Answer] Actually hacking a satellite is not the easiest thing. Most use encrypted communications, they will only be overhead for a short while (unless geo stationary) The command and control systems will not be documented, and the existing control infrastructure will be very well secured. Older satellites might be easier (just because threats have evolved) On the damage you could do, assuming you could hack a satellite. Genocide will be a tall order. I'm going to break down into a couple of categories. **Loud/impressive** Hack the US Military communications satellites. Redirect a few drones to your target area and fire off some missiles. This is probably the option that would give you the largest instant casualties. **Loud/civilian** Make every communication satellite broadcast white noise on all possible frequencies. while it wouldn't be all that damaging, cutting communications would cause a lot of problems. **Subtle/Short Term** Subtly adjust the clocks in the navigation satellites. Aircraft coming into places they shouldn't, boats crashing into rocks, trucks delivering things to the wrong places. It wouldn't take long for people to notice this. They would switch back to other older navigation methods. **Subtle/Long term** Adjust the responses from weather satellites, that hurricane headed for Florida gets no warning. [Answer] Aside from orbital platforms armed with nuclear weapons for fractional orbital bombardment, which is an outlawed weapons system by international treaty, satellites lack the capacity to be directly destructive. So maybe hacking communications satellites would enable your nihilistic coders to infiltrate control systems of conventional and nuclear power plants and power distribution systems, causing internal damage that compromises their operation. The impact of losing the entire power grid would be catastrophic to large societies dependent on distributed agriculture for generating enough food for every body. Similarly, damaging dams and irrigation control nodes via the hacked comms satellites could flood broad areas, further damaging agriculture and maybe industrial sites too. Finally, maybe if the hackers had orbital control of all the satellites, they could execute an insanely complex maneuver and cause all the satellites to group together and crash directly into a major city. The satellites on the outside would burn up on reentry, but maybe enough metal on the inside of the clutch of satellites would reach the surface with enough kinetic energy to do damage. [Answer] # Kill GPS And the rival systems, Galileo, Beidou, Glonass. A breakdown of GPS would lead to a rapid breakdown of logistics and transportation infrastructure. Famine, looting, and civil war follow. Sure, one could organize alternate supply chains. But not on short notice. [Answer] Disrupting communications is already extremely damaging to modern day society. Sattelites control a much larger part of technology than you would think nowadays. Even just shutting them off could disrupt parts of the Internet, GPS, telephone, and media communications. All of these systems are more or less crucial for modern society. Disrupting some communications to a bank, denying people access to their money would seed anarchy already. Not being able to find out what happened from the TV would fuel it tremendously. Disrupting the quality of life of modern people often brings out the worst in them, so just depriving them of a few choice options would be fairly effective. The following chaos and destruction is all out of your hands. To add to this, sending false signals to disrupt supply chains would be fairly effective as well. [KFC running out of chicken](https://www.google.com/amp/s/www.bbc.co.uk/news/amp/newsbeat-43169625) in the UK springs to mind. This was quickly labelled as a "crisis" and people were outraged. Imagine doing this on a much larger scale by sending false messages and rerouting all trucks/supplies to most major corporations. Chaos and rioting would ensue. [Answer] If you spoofed the data from weather sats, plus solar and earth observation sats, you could wreak havoc with the agriculture sector and possibly other areas. Fake hurricane warnings, or suppressing the warning of a real hurricane. Imagine a cat 5 hurricane hit the east coast with no warning. [Answer] Bring the satellites down. Easiest, fastest, most "efficent" way. You might not only bring down a 4 tonnes of mass from 2000 kilometres height. You can also initiate controlled cascade effect practically bombarding earth from orbit. Nuking from orbit is sooooo 1986. If you take down the satellite with one nuke to Iowa or Arizona you not only put nuke to that places but all the additional mass you bring make for a nice mass hitting the earth vaporizing eart, making radioactive clouds. Also a not nice reference but imagine what would happened if 4 tonne satellite falled on Manhattan instead of a plane hitting WTC. ]
[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. Suppose we begin to colonize the moon. Assuming the building materials and biological material are all imported (not taken on-site), would it be possible for the moon to become massive enough to fall out of its orbital and come crashing into the Earth? We should assume the materials are taken from Earth, meaning the Earth becomes lighter as the moon gets heavier. How much mass does that represent? What scale is necessary for such an event? Would the moon need to be covered in tall buildings? Would every structure need to be built out of very dense materials? [Answer] As mentioned in comments, I don't have the full stability answer to hand (although see edit below). But I do have a practical answer. The practical answer is that **no feasible human effort could change the orbit of the moon via Earth-mass-transfer**. Here is how the net attraction between the earth and the moon would change as you moved Earth mass to the moon (Moon is approx 1.2% Earth mass), using Newtonian gravity F= G(M\*m)/r^2 [![enter image description here](https://i.stack.imgur.com/CftbM.png)](https://i.stack.imgur.com/CftbM.png) Wow! Peak 12 times increase in gravitational force?! Okay, sure. I'm still not sure that the change in barycentric rotation won't perfectly compensate for that to leave us in a stable orbit but yeah, there's a big potential change in net attraction. Let's zoom in on the left of the chart: [![enter image description here](https://i.stack.imgur.com/Ris50.png)](https://i.stack.imgur.com/Ris50.png) See that red marker? Waaaaaay down there on the left? That represents moving the ENTIRETY OF THE OCEANS TO THE MOON. It changes the net gravitational attraction by **0.01%**. Therefore, even if mass transfer could destabilise orbits (and I am not sure that is true), the amount of mass transfer that could be achieved is incredibly insignificant to orbital dynamics. EDIT: Having thought about the general stability of mass transfer from the moon to the Earth, I think the question isn't properly defined. To define stability we need to know both the change of mass and the change of velocity of the Earth and the Moon during the mass transfer. Keeping constant velocity sounds like the simplest option, but it is clearly unphysical: imagine we transfer mass such that the Earth and Moon are the same mass; they now have a barycentre [the point about which they rotate] exactly halfway between them --- meaning both must have equivalent tangental velocity around this centre. But we have also assumed that the Earth's and Moon's tangental velocities don't change. Therefore we have a contradiction. We can only solve this by making explicit assumptions about momentum transfer. EDIT2: A practical consideration I forgot to mention previously. Gravity is a harsh mistress that makes moving mass very expensive. If you wanted to build extensively on the moon it would rapidly become preferable to mine materials from the asteroid belt (send a small set of mining materials up-gravity, send lots of mined mass down-gravity) rather than sending up a full set of mass from Earth to the Moon. See <https://xkcd.com/681/> for a rough idea of the Gravity Well energy problem [Answer] **This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. **No.** 1. One has to increase one's momentum to the moon's level in order to actually get to the moon. If you're planning to land on the moon instead of crashing into it; you're basically performing a rendezvous with the moon. Consider normal rendezvous in LEO. The ISS doesn't fall out of the sky when its mass is doubled by a docking space shuttle, because the space shuttle's mass has the same momentum. It's only when these have different momentum and still connect with each other (collide, more like) that the apsides change. 2. By adding mass to Moon, you're removing it from Earth. Therefore, not only do the orbital parameters stay the same, but the gravitational force felt between these two should stay constant. [Answer] No. Just no. 1.6 kilometers per second are required to achieve low lunar orbit. From there, another 0.7 kilometers per second are required to get from low lunar orbit to touch the earth surface. Therefore, our work on the moon would require imparting 2.3 kilometers per second of delta v. If you tried to deorbit the moon intentionally you would have to come up with 1.18 kg km / s of change. If we used the nuclear thermal engine for its ~800 second impulse, we need 1.2 \* 10^23 kilograms of fuel to intentionally cause the moon to deorbit. Since you're trying to colonize, you're soft-landing stuff on the moon. There is no impulse provided to the moon. On the other hand, the mass came from earth so earth gets a little bit lighter, so the moon ends up a little bit further away. Considering the size of the other number, we can assume this is negligible for any reasonable purpose including terraforming the entire lunar surface. Surface area of the moon: 3.8 \* 10^7 km Amount of dirt to coat the moon 10 feet deep: 1.7 \* 10^17 kg Mass of earth: 5.9 \* 10^24 kg. Earth's escape velocity before mass transfer sqrt(2G \* (5.9\*10^24 kg) / 405400 km): 1394m/s Earth's escape velocity after mass transfer sqrt(2G \* (5.9\*10^24-1.7 \* 10 ^17 kg) / 405400 km): 1394m/s No effective change. [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. <https://fivethirtyeight.com/features/what-if-the-moon-were-bigger/> Based on this article it seems that the increase of the mass of the moon would disrupt the earths system of time. We would become locked in an entirely different length of days and years etc. not to mention the ocean tides would be different. And if the mass grows ina region of the moon instead of uniform, the moon might either spin a little or a lot considering the center of its mass would change. As opposed to it not spinning at all right now. But I can’t find any evidence of the moon crashing into the earth, only changing its relationship. ]
[Question] [ > > Since a couple of people seem confused, the players are there to > purchase tech made by human colonists. The tech was made by exploiting > the native alien fauna. The ecosystem of the planet is well documented > but the aliens in question are reclusive tool users so the players > don't know they are smart. The evil company exploiting them DOES know > of their intelligence but chooses to continue capturing and experimenting on them. > > > Setting: RPG Sci-Fi My players will be heading to a metal-rich fungal jungle world where many lifeforms incorporate more metal than the lifeforms on our planet. (I know the chemistry of this is mental and unrealistic but I'm not a biologist and those parts of the science are quite soft. I just want to tell a story.) The planet is a recently settled colony on the near-side of Andromeda. It has been settled by a Medical research company because the planet is a "Super-Earth" (theorised places better for life than earth) It's slightly warmer than earth, slightly bigger and denser, and has plenty of carbon and plant life and liquid water oceans. What the players don't know is that this planet is home to native intelligent life. They look like large metallic purple/pink salamanders with proportionally longer arms and the ability to briefly stand on their hind legs. They haven't progressed much past the tribal stage but many tribes are large and they have pretty advanced metalworking and extraction methods. This comes from the fact that, although they started underwater, they didn't need fire because they evolved to be able to generate intense heat (just go with me on this) and can work with most metals that have a melting point accessible to Iron Age metalworkers. (Using tools they developed to enhance these heat generation techniques but the key thing is that they do not use fire all that often. (It's dangerous and scary and they usually don't need it.) Most of this amphibious species lives in hollowed out "tree-coral" in the oceans of the planet, but they have begun to spread many of their homes onto land. They are also quite shy, the jungle is dark under the canopy, especially at night, they can see fine but the players can't. They're homes do not look from the outside like homes, they look like part of the wilderness (to the players anyway) and they do not speak with vowels and consonants. They speak with an entirely tonal language beyond the range of human hearing. The R&D people who settled the planet know about this intelligent species and are keeping it quiet because the species has some brilliant medical research value. Not because it's alien, other aliens have been discovered, but something unique to them. The players are on the planet to trade with them for their technology. The basic outline of the plot is that they go to the planet to trade, they explore the planet a bit and discover this species is intelligent, then it's up to them whether to overthrow the establishment or to complete their mission regardless. What I am trying to figure out is what I can do to subtly demonstrate that these creatures are intelligent without completely giving the game away. What elements can I add to the world that my players will stumble across and begin to question? I can demonstrate intelligence unequivocally but that's not what I want to do. What would they discover in the woods that might make them question the sapience of native life? [Answer] I have a bit of problems understanding the basic setup: > > The players are on the planet to trade with them for their technology > > > Does this apply to human settlers? Anyways I don't think this is a concern for the requested features, so I will ignore issue (correct me if assumption is wrong). There are several ways a species can demonstrate being "intelligent" (assuming this adjective has universal meaning, which it hasn't): * Use tools and use tools to make other tools, recursively (using a stone to smash something is *not* enough). * Having a complex language (with grammatical and syntactic rules; simply having names for things is *not* enough). * Having an *episodic* memory (the ability to remember single events, not just to learn by experience). * Having some form of art (e.g.: drawing, however crude; rhythmic percussion). * Wear "clothes" of some kind, ornaments and/or pouches. * Understand any kind of mathematics (e.g.: arithmetic and geometry) All these capabilities can be hinted in rather subtle ways before "absolute proof"; a few examples: * Tools: + use something taken from an animal (a sharp fang as knife) + use something *resembling* something natural (a stone or metal knife shaped as a tooth) + add something to basic tool (a handle made with leather straps) * Language: + it is not necessary to be a linguist to learn a language. + notice a sound refers to an emotion (e.g.: danger) + notice a certain sound refers to an object (common names) + notice a certain sound refers to specific object/person (proper names) + someone tries to teach you his language. * Episodic memory: + someone remembers you. + someone gives you back something you lost. + someone gives you *a copy* of something you lost. * Art and religion: + find a stick planted in the ground + find a line of sticks planted + sticks ornamented with bone/feathers/leaves + series of sticks, progressively more ornamented leading to an ample circle of strange-looking sticks. + aliens, normally very shy attacking you as soon as you step in the "taboo" circle * Clothes: + swimming people won't have loose garments; what they wear can be mistaken for own skin. + pouches can be mistaken for marsupium-like "natural" pockets. + you see someone detaching a pouch. + amulets or ornaments worn by some alien. * Mathematics: + you can discover that after you suspect intelligence and try to commerce with aliens. Many variations are possible on each theme, but I think this could suffice to fet you started. [Answer] Written communication. It is not unreasonable for your intelligent species to leave markings to communicate with each other. These markings may not immediately be recognisable as writing - they could just be strange markings upon leaves. In fact, if there were a lot of them, they could easily be believed to be natural leaf markings at first. They could also be markings on trees, or rocks. Considering your species ability to merge their homes into the natural environment, it is quite likely their writings and signage would be too. [Answer] Tool marks. One of the things that human's consider to be *the* benchmark of intelligence, in animals as well as people, is tool use. Tool marks on a stone overhang to widen a trail for example may not be immediately apparent but they're easily read as a sign of a tool-using and intelligent creature when your players realise what they're looking at. [Answer] @Ziobyte 's answer nails the ways the players might learn the natives are intelligent. You need one other thing: distraction. If these walking salamanders are the only thing going on in the scenario and if they were exploited by the colonists then they are front and center from minute 1 and the players will know something is up with them. If there are other plausible ways the RPG might go (as regards the narrative) that will take the spotlight off the salamanders and possibly catch the players by surprise. Examples: 1. Salamanders are the intelligent race but that is not known to the human colonists. There is another Sasquatch like group that are the ones exploited. Those things know about and fear the salamanders but don't generally sit down and chat with their human overlords. 2. Ancient ruins. Maybe some of the best tech is from these ruins; salvaged or reverse engineered. Maybe there is good tech still waiting too be had in dangerous places the colonists will not go. Ruin exploring is bread and butter for an RPG. The ruins might be related to the salamanders, or not; maybe built by their distant ancestors. Maybe used by them for ceremonies. Maybe built in the distant past by the horrendous race that enslaved the salamanders and brought them to this planet, but then were overthrown in a rebellion. Maybe a couple of the Horrendous are still hiding in the basement. 3. Monsters. The planet is terrorized by monsters. It turns out that these monsters have something to do with the salamanders - maybe they are terrorizing them too, or maybe they are some sort of larval form... 4. Human hijinks. Weird cults? Hybrids? Humans augmented with freaky found alien tech? The usual good stuff. In any case: dilution is the solution to pollution. Distract your players with pressing, tempting matters (promise of loot, monsters, other candidate aliens) and then you can sneak up on them with the sentient salamanders in whichever way you choose. [Answer] Dam! ... I mean... they can build dams or other projects too large not to notice. Would you say that beavers are intelligent? Or termites that build complex mounds? Nope! Your players find these structures and may think at first that they are natural formations. Then they figure out that the alien species built them, but *still* have no reason to believe the creatures are intelligent. **Only after noticing some of the details of the work, it becomes clear that sophisticated engineering is at play.** ]
[Question] [ **Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- This question does not appear to be about **worldbuilding**, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help). Closed 6 years ago. [Improve this question](/posts/75224/edit) I've read a good number of FTL equals time travel questions and answers both here and on other sites, but for the life of me I just do not get the connection. Let's take a really simple case: say at 12:00 I teleport to some place 30 light minutes away from Earth. If I then pull out a telescope and take a look at Earth I will see the past from 30-ish minutes ago, but if I then teleport back to Earth I'll be back at 12:01 or whatever. I'm not going to end up in the past just because I was looking at it a minute ago. And if I go to a place where time flows differently due to gravity or some other time shenanigans there might be a mismatch, such as spending only 10 minutes there but returning to Earth to find years have passed (or vice versa) but either way it'll still always be in some sort of future. I read several explanations involving "light cones", still don't quite get what they are (so if you bring them up, imagine you're talking to small child) or why should I even care about them, if I have a teleporter then the light comping from an object is not the most up-to date information I can get about it. Several articles also brought up a "light on a train" thought experiment where a light is flashed in the middle of a moving train and is picked up by light detectors, and a stationary observer and an observer on a train moving in opposite direction will see the detectors going off in different order which is supposed to prove something about different frames of reference. But the same thought experiment can be done with sound instead of light and it would have the same results, but as far as I know it's quite possible to break the sound barrier without time travel. Anyway so the question is: assuming a magical teleporter exists is there any logical reason that it **has** to lead to time travel? And if so, what is the exact mechanism? [Answer] This is one of the best explanations that I've ever read, courtesy of [Wikipedia](https://en.wikipedia.org/wiki/Tachyonic_antitelephone#Numerical_example_with_two-way_communication). It deals with FTL communication rather than strictly teleportation but the principle is the same. > > ## Numerical example with two-way [faster-than-light] communication > > > As an example, imagine that Alice and Bob are aboard spaceships moving > inertially with a relative speed of 0.8c. At some point they pass > right next to each other, and Alice defines the position and time of > their passing to be at position x = 0, time t = 0 in her frame, while > Bob defines it to be at position x′ = 0 and time t′ = 0 in his frame > (note that this is different from the convention used in the previous > section, where the origin of the coordinates was the event of Bob > receiving a tachyon signal from Alice). In Alice's frame she remains > at rest at position x = 0, while Bob is moving in the positive x > direction at 0.8c; in Bob's frame he remains at rest at position x′ = > 0, and Alice is moving in the negative x′ direction at 0.8c. Each one > also has a tachyon transmitter aboard their ship, which sends out > signals that move at 2.4c in the ship's own frame. > > > When Alice's clock shows that 300 days have elapsed since she passed > next to Bob (t = 300 days in her frame), she uses the tachyon > transmitter to send a message to Bob, saying "Ugh, I just ate some bad > shrimp". At t = 450 days in Alice's frame, she calculates that since > the tachyon signal has been traveling away from her at 2.4c for 150 > days, it should now be at position x = 2.4×150 = 360 light-days in her > frame, and since Bob has been traveling away from her at 0.8c for 450 > days, he should now be at position x = 0.8×450 = 360 light-days in her > frame as well, meaning that this is the moment the signal catches up > with Bob. So, in her frame Bob receives Alice's message at x = 360, t > = 450. Due to the effects of time dilation, in her frame Bob is aging more slowly than she is by a factor of [[formula]](https://wikimedia.org/api/rest_v1/media/math/render/svg/b46672c009a54f09cf092a8013d319e6ecc56857), in this case 0.6, so Bob's clock only shows that 0.6×450 > = 270 days have elapsed when he receives the message, meaning that in his frame he receives it at x′ = 0, t′ = 270. > > > When Bob receives Alice's message, he immediately uses his own tachyon > transmitter to send a message back to Alice saying "Don't eat the > shrimp!" 135 days later in his frame, at t′ = 270 + 135 = 405, he > calculates that since the tachyon signal has been traveling away from > him at 2.4c in the −x′ direction for 135 days, it should now be at > position x′ = −2.4×135 = −324 light-days in his frame, and since Alice > has been traveling at 0.8c in the −x direction for 405 days, she > should now be at position x′ = −0.8×405 = −324 light-days as well. So, > in his frame Alice receives his reply at x′ = −324, t′ = 405. Time > dilation for inertial observers is symmetrical, so in Bob's frame > Alice is aging more slowly than he is, by the same factor of 0.6, so > Alice's clock should only show that 0.6×405 = 243 days have elapsed > when she receives his reply. This means that she receives a message > from Bob saying "Don't eat the shrimp!" only 243 days after she passed > Bob, while she wasn't supposed to send the message saying "Ugh, I just > ate some bad shrimp" until 300 days elapsed since she passed Bob, so > Bob's reply constitutes a warning about her own future. > > > --- My understanding of what is happening here is that, for both Alice and Bob, the other person is "aging more slowly" due to the effects of time dilation. This effect is symmetrical, so somewhat counter-intuitively, Bob appears younger to Alice at the same time that Alice appears younger to Bob. Since each person exists in the "past" of the other - appearing younger in age - if you send a message from one to the other then it will get there *before* you sent it from your frame of reference. Replace "FTL communication" with "teleportation" or even just "FTL travel" and the paradox is the same. I believe in the above example, Alice's and Bob's given velocities are so fast (0.8 C) in order to exaggerate the effects of relativity and make it easier to grasp. But the paradox still holds for trivial velocities. [Answer] The issue is that, thanks to relativity and everything it brings, things that occur simultaneously in one reference frame do NOT occur simultaneously in all reference frames (or even most of them). The "light on a train" thought experiment is just an effort to prove this, but we'll hold off on that and accept it to be true. Let's say I have two synchronized clocks on Earth and Mars. If we have a spaceship travelling fast enough in the direction from Mars to Earth, the clock on Mars will appear to be running behind the Earth clock. The faster the spaceship is traveling, the farther behind the Mars clock will appear (hours, days, even YEARS if you're going fast enough). So if you decide to teleport (instantly) from Earth to the spaceship, then to Mars, you'll get to see how slow that clock was running. But weren't the clocks synchronized from the perspective of Earth and Mars? So you just teleport back to Earth (instantly), and you've arrived back where you started, but in the past. I emphasized that the Mars clock could appear years (millenia, any amount of time) behind the Earth clock so you know that the time it takes for information to go between Earth and Mars (like with a telescope) doesn't really matter. Now, I'll resummarize the "light on a train" thought experiment, just using Earth/Mars again. Suppose we have a broadcast tower halfway between Earth/Mars, airing some TV show at exactly 5PM. Again, the clocks on each planet are synchronized. The boadcast tower is placed exactly halfway so everyone gets to enjoy the show at the same time. But suppose we're on our super-fast 0.99c spaceship. We're traveling near lightspeed from Mars to Earth. From our perspective we feel quite stationary though, and it's Earth and Mars and the broadcast station that are zooming past us at near lightspeed. Because light travels the same speed in every reference frame (which is not true of sound), from our perspective the broadcast will struggle to reach Mars. Because Mars appears to be running away from the broadcast at 0.99c and the broadcast can only travel at c, it would take 100x longer than usual for the signal to reach Mars. Earth appears to receive its signal almost twice as fast from our perspective. But since we know that the show starts at 5pm, the signal must reach Mars at 5pm, and so Mars' clocks must be running slow. But only from our perspective. Final note, I believe you can have instant teleportation without allowing time travel if you agree on a single reference frame (say, our solar system) to be able to teleport instantly within. The only consequence of this is that teleportation won't appear instant from all reference frames. From the perspective of our same spaceship, people teleporting "instantly" from Earth to Mars will take quite awhile, and people teleporting from Mars to Earth will show up before they left. EDIT: I think I've messed up some numbers. The time difference between Mars and Earth wouldn't be anywhere near 100x thanks to length contraction and time dilation and such. But aside from the actual numbers, I think everything else remains correct. [Answer] FTL does not lead to time travel if there is a preferred absolute frame of refererence -- an "Ether" equivalent -- against which FTL (or instant transportation) is measured. Lacking that, FTL ends up being relative to your current frame of reference. And when you move "normally", time and space being to bleed into each other a bit via a rotation like mechanism. You say "the same time" at two far apart locations, but how do we measure it? In relativity, there is the future (things light can reach from now), the past (things light could have reached you from), and elsewhere. If we define a "at this moment" plane through space-time, when you move the angle this plane cuts through space time changes. If you move towards Alpha Centauri, the "same time" there *moves backward in time* relative to being "stationary" relative to Alpha Centauri. So you send a message to Alpha Centauri "instantly" in your current frame, and then they send a message back, and it arrives *in your past*. We can avoid this by inventing an absolute frame of reference against which "the same time" is measured. Doing so would require rebuilding most of physics and somehow deriving our current physics as a special case. [Answer] The problem is that simply knowing what time it is on Earth doesn't let you know what time it is 30 light-seconds away, because the answer to that depends on your inertial frame of reference. It could be anywhere between 11:59:30 and 12:00:30 (from the Earth's point of view, which isn't necessarily the same as yours, because you may be moving with respect to the Earth). So you can enter a frame of reference where 12:00:00 on Earth is 11:59:45 at your destination, and teleport there. Then you spend 10 seconds changing your frame of reference, after which it's 11:59:55 where you are, but now it's 11:59:40 on Earth because of your new frame of reference. Then you teleport back, arriving 20 seconds before you left. [Answer] This is a fun question to consider. I look at it this way: both time and distance travel must be perceived in order to be measured, and the measured result is going to depend on from whose perspective you choose to view. Time. If you are the one perceiving the change in time, you will always be measuring from your own now. Even if you go back into your own past, you are also in your own present, because you remember your past the first time you perceived it. If you are traveling alone, no one except you can measure time from your own perspective. Someone observing your change in time to your own past where you do not return, will perceive you disappearing from their own time. If you return to your time starting point, they will not be able to perceive any change in time existed for you at all and it well be as if nothing happened, even though for you, you experienced some change in time. Distance. Same conditions apply for distance as time, with one important difference: you cannot physically be at a previous place and subsequent place at the same time like you can in time travel. Therefore, you would think both you and an external observer can perceive your change in distance at the same time with the same results. We know this to be untrue though because of the limitations of the speed of light and that with two different points of perspective, you each will make different measurements of distance you traveled. The distance traveled from your perspective will be different than that of the other observer. Einstein called this the relativity of simultaneity. Explanations of your question proposed that say you reappear in the past are only seeing the answer from the perspective of someone perceiving from the past point in time. You, measuring from your own timeline, will know that you are in your present, which is sometime in your future as compared to your starting measurement point. [Answer] FTL travel IS time travel, as seen from some observers. Consider this experiment. Joe is a peaceful fellow, but he sees a TV program that tells him that people on Mars have cooties. Joe is now radicalized, so he puts a bomb in his FTL teleporter, sends it to Mars, and blows it up. Sally, an observer in a spaceship floating above Mars sees this sequence of events: first a bomb appears, destroying Mars, and then, later, light from Earth reaches her, showing Joe watching the TV program. Joe's machine appears to send the bomb back in time. This is why FTL and time travel are deeply irrational concepts--if they exist, they destroy causality, and a large portion of rational thought and science stop making sense. This is the meaning of relativity: there is no special, privileged reference frame. We are on a planet that is moving, around a star that is moving, and the galaxy is moving. Nothing is standing still. Causality means that every cause comes before its effect, no matter who is observing it. This must remain true for all observers, no matter how they are moving. This is only possible if nothing moves faster than light. Joe's FTL teleporter vanishes in a puff of logic. Now he has to send his bomb on a rocket traveling slower than light, and Sally will see the rocket launch before Mars explodes. Everyone will see that the cause happened before the effect. [Answer] The simple truth is in order to invent a time machine you also have to invent a teleportation device. Here is why. Supposing you invent a time travel machine, and set it up in your living room, and decide you need to go back six months because you forgot your anniversary and the wife has been giving you heck ever since. So you get in, dial back the date, sit back and press GO. POOF you jump back six months. Then you immediately die. Why? Because six months ago the earth was on the other side of the sun. You went back in time but not in space. You re-emerged in a vacuum. So, if you invent a time machine you need to not only move in time but also reappear at a different location... aka.. teleport. OK so what about the other way around. If I want to teleport from say the moon to the earth and I look up from the moon and see the spot I want to land. I can't just dematerialize and re-appear at that spot. Why? Because the spot I see is not in the same time frame as I am. Light takes time to reach me. So the earth has moved and turned a little bit more than what I can see or measure. If I want to land on that spot I have to move through space and also go back In time a little to "back up the earth". Of course all this is even more complicated by the fact that you have to match arrival velocities and need incredible accuracies to not materialize 1mm too low. ]
[Question] [ A bit of mythology: In the beginning there were two dragons fighting for dominance of the universe: one of light and one of dark. This battle had gone on forever. Both dragons were tired of the battle, and wanted to end their eternal struggle. The Dark Dragon powered up to unleash an attack that would end it once and for all, but in doing so it left itself open to a counterattack. The Light Dragon, seeing the opportunity launched its own attack, defeating the Dark Dragon once and for all. The Dark Dragon's essence would not be denied, however. In attacking , but getting injured... contaminated in the process. The Light Dragon needed to rest, so it curled itself into a ball, creating a type of cocoon for itself. This became the water we see that is most of the planet. Only the dragon's spines are seen..Breathing out it exhaled much of the air from its lungs which surrounded it, thus creating the atmosphere. Creating self-contained floating platforms of vegetation, it filled world with animals, and created the draconic races, to act as its protectors, before going to sleep. Because these races are actually living on the dragon's life force (and in fact, its body) any attempt to completely heal the dragon would cause an apocalypse that would end the existence of life due to the fact that they were only created for the sole purpose of guarding the dragon while it healed - but the dragon world that made them didn't anticipate things to get so out of hand that there would be any controversy over its reawakening. There is a faction (religion) of dragons that seek to totally heal the dragon that makes up the planet by eliminating evil and thus bring about a new age of peace and prosperity (kinda a Gaia type of a thing). They feel they're doing the right thing. Good actions, good thoughts, good behaviors help to heal the dragon and hasten its awakening. There's another faction (religion) of dragons that seeks to cause so much evil and chaos that the dragon will forever be asleep and thus allow life to continue indefinitely. This too would bring about a disaster, as if the evil spreads enough, the dragon would die, also ending the life on the planet because if it dies, so too does all life. War, violence, and every type of evil spreads the corruption, preventing the dragon from healing completely. There's a third faction (religion) of dragons, which seeks to balance evil and good thus preventing the dragon they're living on from totally healing, but not having it so polluted with corruption it dies. In this convoluted ideology of good and evil, is it possible to be fair to all sides? [Answer] I think it depends A LOT on the specific situation. Basically, in your world the names "good" and "evil" have been attached to specific, objectively-defined actions: things that heal the Light Dragon, and things that hurt the Light Dragon. (I'm assuming people understand what these are. If they don't, that would be interesting in and of itself, but the factions must all understand the importance of this information so I'd guess they'd make it a priority to know as soon as they can.) But, can it really be the case that everyone agrees that things in the first category are "good" (in the usual, moral definition) and things in the second category are evil? It doesn't seem possible to me. People in real life use "good" and "evil" to refer to concepts that are interpreted differently by different people, according to their subjective value systems. This means that it might be possible to "cheat" in a sense, and balance "good" and "evil" (in the Dragon-defined sense) in a world that still seems to have more good things than evil things according to the *personal* morality of interested parties. Maybe your story won't get into these kind of issues much, but for example: what if some people decide to deliberately make "sacrifices" to prevent the dragon awakening, such as undergoing violence through a ritualized form of warfare. Is this "evil" and harmful to the dragon, since it is violent? Or is it "good", since the participants are doing it for a noble reason (and therefore ineffective, or in fact counterproductive)? Would they need to actually kill one another to be successful, or might it be enough to just cause temporary physical pain? Your world has people, so there will certainly be criminals, including ones who have committed quite terrible crimes. Is the violent execution of criminals like this "good" or "evil"? These are just a few examples; there will be many more possibilities for a person's moral judgement of "good" and "evil" to conflict with your world's necessarily objective and accessible definitions of "good" and "evil". [Answer] What you describe sounds like an Eastern philosophy. Rather than cast-in-stone concepts of "good" and "evil," they have complementary fluid concepts like "yin" and "yang." The biggest challenge of writing such a cosmology will be overcoming one's own opinion of what "good" and "evil" are. When you have actors like the three groups you describe, those concepts get murky quickly, and one's own opinions regarding those two terms can limit your imagination. Consider Zorg, one of the villains from The Fifth Element: > > **Priest Vito Cornelius**: I try to serve life. But you only…seem to want to destroy it. > > **Jean-Baptiste Emanuel Zorg**: Oh, Father, you're so wrong. Let me explain. [closes office door, places an empty glass on desk] Life, which you so nobly serve, comes from destruction, disorder and chaos. Take this empty glass. Here it is, peaceful, serene and boring. But if it is [Pushes glass off table] destroyed… [robot cleaners move to clean broken glass] Look at all these little things. So busy now. Notice how each one is useful. What a lovely ballet ensues, so full of form and color. Now, think about all those people that created them. Technicians, engineers, hundreds of people who'll be able to feed their children tonight so those children can grow up big and strong and have little teeny weeny children of their own, and so on and so forth. Thus, adding to the great chain…of life. [Desk prepares a glass of water and a bowl of fruit] You see, Father, by creating a little destruction, I'm actually encouraging life. In reality, you and I are in the same business. Cheers. > > > For a more traditional example, your third faction is remarkably similar to the behavior of the Jade Emperor in Journey to the West. In Chinese mythology, maintaining order is often prioritized over good and evil. Good and evil are often shown to be tricky things to capture, but everyone in China knows the order of things. [Answer] ### Consider a situation where "good" has won and "evil" is in remission. I'm going to be quite crude about the meanings of good and evil. All is life and light and order, death and darkness and chaos have been banished. Taking this to its illogical conclusion, because that's where it's going, new life is born, trees grow, nothing dies and it's never dark. But light and dark are part of the cycle of life, some animals need the darkness and some need the light. We live on the death of others, the death of plants and animals. The butterflies and the bees will be fine for a while but the lions and tigers are going to be starving. Predators live on the edge, in the chaos, they are the thing that goes bump in the night, do they too not have an equal right to live? With no death life becomes unbearable, crowded and hungry. With no darkness it becomes too hot. With no chaos it becomes dull and meaningless. It would not take long after the loss of the darkness for the light alone to be considered just as evil and for people to seek the darkness and chaos. Either one without the other takes you to a very bad place. *The eternal summer is no better than the eternal winter.* [Answer] "Is it possible to be fair to all sides" sure as long as you don't betray any side as a one-sided group of fanatics. Give them dimension, they truly cared deeply about what they believe but that's not all they are. Their belief might be at the core of what they do but many things Branch off of it, their families friends Hobbies, maybe one of them's a history nut or an extreme sports enthusiast. You also must make it clear that they're not in it for money or power, they must really believe what they're doing is good and right for all and that the other side is misguided at best downright evil at worst and they must protect the world from them. Even if it cost them their lives. To put it simply being fair to all sides has little to do with the actual mythology and more to do with the portrayal of characters on either side. If you want to see a good example of this I would suggest you read the book " the black God's War" you can download it for free on Amazon. [Answer] # Stretching labels too far devoids them of meaning If agents of some ideology are capable of playing for a collaborative victory, then mutually-beneficial deals can be done with them. What else do you need? You can imagine two factions - green and blue - who hate each other's guts. However, mechanically they're not so different - agents of both factions can collaborate (which is a prerequisite for having a society). Now, you can label each faction "good" and "evil", respectively, with genocide of "evil" infants coming off as "good" because they will only bring more "evil" to this world. This is basically begging for deconstruction because "good" character will be different from "evil" no more than characters from different countries. If you want to have evil characters you'll need ones that one can not strike mutually-beneficial deals with. Religious fanatics / madmen fit here. However, self-sufficient society made of those people would be hard to achieve, and evolving society-oriented brain without tendencies for cooperation would be hard either. If you want to have characters that wear black and skulls you can make it fashion fad among one faction. However, note that their party allegiance does not really mean much and any "evil" character would be as likely to be a nice person as his "good" counterpart. Also, "good" side is just as likely to wear black and skulls. If you want to have two competing factions you can either use basic xenophobia - which works fine, although not on all levels of development - or let them have different ideas of how the world works, so they can agree on what they eventually want but not how acieve it. The latter one looks like what you have, but with sufficient information it can be solved. Teaching someone to do what his common sense tells him to do usually goes without evidence, so "good" side can easily be wrong. "Evil" side, on the other hand, should have convincing evidence that what they do is right. Present it to "good" faction, experiment on actual definitions of "good" and "evil", game the system. Who defines if the action is "good" or "evil"? E.g, saving one person vs N chicken - is it "good" or "evil"? Does it change with different N? If that is defined by original dragon's mind then there would be differences between dragon's moral code and society's moral code. That can be gamed by focusing on "evil"-raising stuff that is "evil" in original dragon's moral code but is benign in society's, like Mandatory Masturbation program or Healthy Diet prorgam or No Stupid Hats day. On the other hand, if definitions of "good" and "evil" are taken from used language then simply switching "good" and "evil" will do. You can save all puppies you want, this is "evil" and thus delays the apocalypse. Using some intermediate words to facilitate the change (and spread it through several generations) would be just fine. [Answer] You may want to focus on the many different motivations an individual dragon might have for following either of the three factions. Good: this is an interesting faction since we are used to the idea that doing good deeds will lead to good things, but how many humans who are overall good people still do righteous deeds if it meant the end of the world? This group could mostly consist of the truly altruistic dragons who want the light dragon reborn, but maybe there are others who do good but secretly that the evil faction balances them out because they don't want the world to end (maybe they would betray the good faction if they see signs that the light dragon is close to waking). What if there are dragons who are not good by nature, but want the world to end, and do good deeds contrary to their desires just to bring about the apocalypse. Evil: This faction is kind of difficult, since normally evil is associated with selfishness, but in your world doing a lot of evil would bring about the end of the world also. If the evil dragons know this, that group would be limited to nihilist "watch the world burn" individuals. I think it would be more interesting if the evil dragons believed that completely killing the world dragon would ensure that their world lasted forever. This way some evil dragons argue that their end goal is good (preserving the world) and you would get dragons who are forced to do evil deeds despite their good nature (and suffering internally) because they believe preserving the world is more important. You could have interesting conflicts between good dragons who do evil just to preserve life and dragons who do evil because they enjoy it; those groups would cooperate for their common goal, but hate each other. Neutral dragons would could have the largest variety of motivations: good but don't want the world to end, want to wait and see if the light dragon can give them some signore of what to do, evil but worried that if the wold dragon dies there will no longer be any need to do evil, those who value Balance andue don't care about the larger consequences, and those who are simply unsure what to do. ]
[Question] [ The [Mokèlé-mbèmbé](https://en.wikipedia.org/wiki/Mokele-mbembe) (meaning "one who stops the flow of rivers") is a legendary water-dwelling creature of Congo River basin folklore, loosely analogous to the Loch Ness Monster in Western culture. It is often described as looking like a small sauropod, with a body roughly the size of a hippo. Obviously a living sauropod, in even the most remote jungles, is rather unlikely. Other than being simply a dinosaur, what other animal could describe the Mokèlé-mbèmbé? A list of all of the Anatomically Correct questions can be found here: [Anatomically Correct Series](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798) [Answer] Don't forget the lovable [Manatee](https://en.wikipedia.org/wiki/African_manatee). They exist in the Congo river, though only as far up as Livingston Falls, but they live in the Niger river all the way up to the [Inner Delta](https://en.wikipedia.org/wiki/Inner_Niger_Delta), one of the biggest freshwater swamps in the world. Manatees just need a lift upriver to establish themselves in the Congo. --- [![Picture of a Florida manatee underwater in King](https://i.stack.imgur.com/1txy8.jpg)](https://i.stack.imgur.com/1txy8.jpg) Credit [National Geographic](http://ngm.nationalgeographic.com/2013/04/manatees/white-text) It's not quadrupedal, but it is herbivorous, gentle and exceptionally cute when taking a nap. Like the sightings of other aqueous creatures, reports are often conflicting, fear clouds judgement and rumors spread quickly. Manatees are also known for their mistaken identity in relation to mermaids --- ### Evolution From the [wikipedia entry](https://en.wikipedia.org/wiki/Evolution_of_sirenians): > > Sirenia is the order of placental mammals which comprises modern "sea cows" (manatees and the Dugong) and their extinct relatives. They are the only extant herbivorous marine mammals and the only group of herbivorous mammals to have become completely aquatic. Sirenians are thought to have a 50-million-year-old fossil record (early Eocene-recent). They attained modest diversity during the Oligocene and Miocene, but have since declined as a result of climatic cooling, oceanographic changes, and human interference. Two genera and four species are extant: Trichechus, which includes the three species of manatee that live along the Atlantic coasts and in rivers and coastlines of the Americas and western Africa, and Dugong, which is found in the Indian and Pacific oceans. > > > Manatee share a common ancestor with elephants. --- ### Related Extant Species [![Amazonian Manatee](https://i.stack.imgur.com/ZNu7I.png)](https://i.stack.imgur.com/ZNu7I.png) Amazonian Manatee [![Dugong](https://i.stack.imgur.com/XPLLv.jpg)](https://i.stack.imgur.com/XPLLv.jpg) Dugong [![West Indian Manatee](https://i.stack.imgur.com/X2eOz.jpg)](https://i.stack.imgur.com/X2eOz.jpg) West Indian Manatee --- ### Interesting [note on Dugong](https://en.wikipedia.org/wiki/Dugong#Importance_to_humans). Dugongs' or sea cows' hides have been thought to have been used as coverings in the building of the Old Testament portable worship tent known as the Tabernacle. [![A cave painting of a dugong – Tambun Cave, Perak, Malaysia](https://i.stack.imgur.com/jJbcP.jpg)](https://i.stack.imgur.com/jJbcP.jpg) A cave painting of a dugong – Tambun Cave, Perak, Malaysia [Answer] The creature is described as rather large, with size estimate ranging from as small as a hippo to the size of an elephant. The largest reptiles, the [saltwater Crocodile](https://en.wikipedia.org/wiki/Saltwater_crocodile) has the required length, but its height, even at the maximum is lower than waist height. **The Komodo Mbèmbé** My next guess was at the [Komodo dragon](https://en.wikipedia.org/wiki/Komodo_dragon), the largest lizard. I had thought maybe this could be a freakishly large specimen. Fortunatly the largest ever found was 3.13 meters long (around 9 feet) making for a good base point. But unfortunelty the skeletal structure of lizards make even the komodo dragons size difficult to support, I doubt that even an artificially created Komodo Mbèmbé could support the weight, never mind a naturally evolved one. The next problem is more subtle, [**Island Gigantism**](https://en.wikipedia.org/wiki/Island_gigantism), the thing that made the Moa, Haast's Eagle and Tenerife giant rat so, well, giant. The Komodo dragon is only found in the Indonesian islands of Komodo, Rinca, Flores, Gili Motang, and Padar, most of these it is the dominant predator. around 4 million years ago a similar species was found in Austrailia though even going back, we have yet another problem. Its diet, meat; big animals need a lot of food to be big, shocker I know, with other large predators in the congo, even if our Komodo Mbèmbé wasn't outcompeted, it would have extreme difficulty hunting in the jungle. It was around here I realized I was in over my head. Carnivorous giants are super rare (with the largest land predator being the polar bear, which is much too small) so carnivores were out of the picture. The bone structure of lizard limbs didn't really even allow for the size or shape we need; [![enter image description here](https://i.stack.imgur.com/p3iR7.jpg)](https://i.stack.imgur.com/p3iR7.jpg) **The Mokèlé-Pangolin** I then went down into the line of mammals, specifically native african giants. This is when I discovered the perfect candidate; the [giant Pangolin](https://en.wikipedia.org/wiki/Giant_pangolin). [![enter image description here](https://i.stack.imgur.com/LJdEj.png)](https://i.stack.imgur.com/LJdEj.png) At an average of three feet, may seem too small, but keep in mind that mammals scale up in size rather well, escpecially when compared to lizards. ALso as an insectivore that feed on massive colonies we have a base for a large stable diet, though for the desired size (minimum of a hippo) we need to edit its diet to include leaves and fruit, this altered diet may have even caused the gigantism. The Mokèlé-mbèmbé is almost always described with a long neck, which is why I almost quit this Mokèlé-Pangolin endeavor until I realized that by including fruit as a staple within its diet, I have an double excuse for a long neck; it allows for the creatures to easily grab at higher up fruit and leaves, much like the giraffe. In case this didn't tickle your ''Of course'' Fancy, its habitat also lines up with sightings of the Mokèlé-mbèmbé; [![enter image description here](https://i.stack.imgur.com/z4Qxj.png)](https://i.stack.imgur.com/z4Qxj.png) [![enter image description here](https://i.stack.imgur.com/LGYrP.jpg)](https://i.stack.imgur.com/LGYrP.jpg) [Answer] ground sloths might be a good choice, they went extinct only very recently in some parts of the world. The hard part is getting them to africa. so you might want to have a pangolin following a parallel evolutionary path. [![https://s-media-cache-ak0.pinimg.com/originals/f2/c0/e6/f2c0e6cf1ee358ed558d85f2504fa716.jpg](https://i.stack.imgur.com/D6Iin.jpg)](https://i.stack.imgur.com/D6Iin.jpg) [Answer] The mokèlé-mbèmbé could be a microbat that adapted to climb through trees rather than fly. It may increase in size, and become flightless. They may still be able to glide, and use this ability to swoop into rivers and eat fish. They may evolve to live soley in the water, using their wings as fins. This could lead to their hair fusing into scales like a pangolin, to make them more streamlined. They could also evolve to go onto land to suppliment their diet with plants. They may also become extremely large, and become predators of larger prey. They might use a sharpened snout to stab at prey, which might later turn into a long horn. In order to use this horn more effectively, their neck would elongate. They may also gain a more muscular and dexterous nose, to make it easier to eat. This may eventually evolve into a trunk. They may change their diet to feed on hippotamodes, and may increase in size further. They may evolve to dig out underground nests in rivers to keep their young. Due to lack of space, they may evolve to dam rivers in order to increase the amount of space for their nests. This will result in a mokèlé-mbèmbé ]
[Question] [ As discussed in [this question](https://worldbuilding.stackexchange.com/questions/5158/maggots-at-a-party-how-would-alien-races-dine-together) certain social activities such as eating could be hard to support between alien species with very different dietary requirements and eating customs. What social activities though would be possible? We can assume that the aliens in question have biology compatible enough that they can survive in similar conditions to each other. [Answer] Only thing we can safely assume of these aliens is that they are sentient and that we have some way of communicating with them. And even then different species might have significant differences in particular areas of mental performance. Even games of chance usually require estimation of probabilities and reactions to such games would vary between species. A computerized co-operative game that adjusts gameplay based on the data it has about the players might work. Say a MMORPG that gives each player a character and user interface compatible with their actual abilities, and adjusts all challenges based on the characters in an "additive way" so that all characters are needed and all players involved. As Pavel Janicek noted a co-op game would help with diplomacy. Additionally players would become more adept at communicating with each other which has value beyond diplomacy. The computer would acquire lots of information about the mental patterns of the players, which would feasibly have value to the species controlling the game, if some players come from cultures that are relatively unknown. Was going to put this as comment to Pavels answer, but this way I do not need to worry about character count and Tim gets more answers! [Answer] **Logical games** is my best shoot: * equalizes biological differences, so the intelligent spiders from planet *Arachnae* will have no extra gain in climbing or in having extra ... uh ... hands? * We can find a game which can be solved even by color blind species from *Sirius* * Because we all got to the level of space exploration **and** interstellar travel, it is safe to assume, that all species involved love to solve tasks which involve logical thinking And bonus, we can always throw in **co-op board game** to be played by Romulans, Humans and Klingons *together,* where the game can be won only by *working together* thus helping the common diplomacy [Answer] Cultural shows, Seminars, Conferences between scientists from different planets about their respective specialties, Tech demonstration CES for computers of the galaxy, trade exhibits on new weapons systems, new starship designs etc. Then there is the annual Nascar Universe [Answer] Social activities are derived from shared values. We can see differences here even among human cultures, and with alien cultures it becomes even broader. For example: * Musical and theatrical performances are popular, *but* some religious men won't watch women perform, some religions and cultures find certain content objectionable, and tastes vary. * Sporting events are popular, but some find the violence in some sports objectionable. As for *participating* in sports, some value skill and competitiveness and others value inclusiveness. * Social games are popular with some, if there are shared interests. People who favor Trivial Pursuit, Axis & Allies, EuroRails, and Apples to Apples tend to be looking for different things in their participation. * Travel/sight-seeing is something many enjoy, but the "spend the day on the beach" people can clash with the "spend the day in museums" people. It's entirely possible that a human and an alien will find a common social interest that two humans, or two aliens, wouldn't. So instead of thinking of this at the species/racial level, try to think about the values of individuals or smaller groups. [Answer] First and foremost: sex. Sounds silly? Maybe. But if we assume, that alien species won't have our religious/puritanical views on sexual intercourse it's actually the most logical thing to do. Most lifeforms we know of on Earth have very strong urge to reproduce at all cost. Among mammals and birds there are studied and documented cases, when a male of one species rapes a member of another (gender of the raped specimen is not always important), because a female of their own is unavailable. I won't provide links for that, google at your own risk. Taking that into account it is safe to assume, that aliens would be driven by similar instincts - they did evolve somehow, didn't they? So what would be the point of interspecies mating between aliens? Pleasure, boredom, a desire to produce a hybrid superior to both parents... take your pick. Now that we have that out of way, let's focus on something less likely to mark my post as a spam. General information exchange is a good start. That's what most adult humans do, when they meet in groups - smaller or larger. The topics depend on participants. It may be weather, gossip, sports, cars, books, politics, or million other things. Why wouldn't aliens simply talk to each other? They surely have a lot of information to share, whether it's something about their planets or something about current events. Once we're done with the small talk, how about business? Different parts of the universe surely have different technology, resources, designs, artworks... It doesn't have to be some big business contract: ``` "Hey Zog, what a nice necklace you have there, and my Bama would kill me if I won't bring her something nice. I've heard iron is rare on your planet, how about we trade?" "Sorry, Zama, that belonged to my mother. But I have a different one in my luggage, let me show you" ``` Feel free to take it from here. As long as there is stuff in this Universe, there is someone willing to buy it and someone willing to sell it. Some games, physical or intellectual, would surely be in order as long as you have two species valuing the same thing in one room. If math skills are necessary to find a mate for species *Leibniz* an *Newton* they will be throwing calculus at each other before you know it. Some poster mentioned "equalizing chances". Why would anyone even try to come up with such a game? There will always be someone with an advantage and someone with a disadvantage, no matter how you design the game. This holds up even to such a small group as the few of us answering this very question, not to mention entire universe. I suspect that the rules will be mostly crated ad hoc, and will be somehow based on what is important for survival on different planets. We humans highly regard games like chess where you need to think, because it was our brain, not our muscles which helped us eat the mammoths (on the other hand it's the big muscle guy who pushes the brainiac out of the way and takes the female, but hey, it hasn't been long since we climbed down from those trees). And lastly - religion. In my first paragraphs I assumed, that it's not an issue, but it's your story - you can have your aliens as religious as you want. And every self-respecting religion tries to find as many followers as it can. So why they shouldn't try to convert each other? That can be a funny story arc to write. Especially if some of those religions have some really strange rituals. In this case - there is nothing limiting your creativity. You can sit back and enjoy yourself. ]
[Question] [ ## Premise I am trying to piece together a world where a country has two territories. One territory is very far away from the other. Between the disjoined lands are long stretches of hostile enemy territory. Having distant territories is hardly a novel affair; the Romans, Persians and Ottomans boasted vast ones. However unlike many of such empires, the country in my world does not have a continuous slew of land. For a real world historical analog, we can look at the former state of East Pakistan: [![enter image description here](https://i.stack.imgur.com/9JNSR.jpg)](https://i.stack.imgur.com/9JNSR.jpg) It is clear from the map that the territories would face numerous logistic and strategic complications. East Pakistan was almost 2000 miles away from West Pakistan, and it stands to reason that this geographic dimension added to the cultural and political turmoil that ultimately drove East and West Pakistan apart during the Bangladesh Liberation War. East Pakistan is certainly a decent starting point, but is by no means the best case scenario for a distantly disjoined country. One could arguably assert that the military presence West Pakistan had in East Pakistan ultimately worked against them. Allegations of genocide along with other complications led to the demise of East Pakistan in less than 20 years. I would like my world's disjoined state to last much longer. **Question:** What is a viable military strategy for a disjoined state to secure sovereignty in the long run? **Further Clarifications** * Terminology: I will refer to the larger, main territory simply as "the state." While I will refer to the far flung territory as "the isolated territory" * Of course the state is larger and stronger, the isolated territory is smaller and weaker but not a pushover. The isolated territory has enough supplies and troops for the short-term, but will not survive prolonged warfare or lengthy attrition * The isolated territory is able to be self-sufficient in terms of sustenance, but it is landlocked and faces logistical challenges * Rivers from the isolated territory reach the sea. * Between the state and the isolated territory are roughly 2,000 miles of hostile enemy territory (depending on route) * There are a total of 3 neighboring states, all of which are hostile * Military strength is roughly equal between all 4 states * Diplomacy has failed, alliances could not be forged, deals could not be struck * The isolated territory's narrative is largely out of scope, but you may assume it's existence is rather new * The loyalty of the isolated territory to the state is absolute. However, slight cultural differences exist. * Era: Roughly middle ages (knights on horseback and the like) Here are maps: [White = disjoined country] all other colors are hostile. * You may generate the original [here](http://www.d20srd.org/fantasy/world/) * Seed:1492628839 [![enter image description here](https://i.stack.imgur.com/ZcaGs.gif)](https://i.stack.imgur.com/ZcaGs.gif)[![enter image description here](https://i.stack.imgur.com/bZOtt.gif)](https://i.stack.imgur.com/bZOtt.gif) [Answer] **Play off blue against red. The parallel is Mongolia.** [![mongolia](https://i.stack.imgur.com/95NOA.jpg)](https://i.stack.imgur.com/95NOA.jpg) <http://www.citiesandplaces.com/where-is-mongolia-located-mongolia-map/> Mongolia is a landlocked buffer state between Russia and China, and before that between the USSR and China. It serves as a buffer, reducing the shared border between these two powers, curbing immigration and reducing tensions. Should one of the bordering powers make a move it would be seen as threatening to the other. In modern days there is even more similarity to your situation: the involvement of a distant power (the US) in Mongolia bringing wealth and resources. Neither of the bordering powers mind this much as both see it facilitating the action of Mongolia as a buffer. <http://www.russia-direct.org/opinion/mongolia-uncontested-buffer-state> > > Although Mongolia would not act as a full buffer against China, it > certainly reduces much of the border space and, as Chinese migration > to eastern Russia is increasing, can reduce the uncertainty of illegal > border crossing by Chinese migrants. In this sense, the U.S. pivot, > and subsequent “employment” of Mongolia to contain China not only > would make sense to Moscow but be welcomed by the Kremlin – if > Washington will do the work that will ultimately benefit Russia, why > should Russia complain? As long as there are active relations between > Moscow and Ulaanbaatar, there is no tangible loss for Russia, merely a > stronger border state that is increasing its security capacities and > border security, while continuing to counter the large Chinese > presence in the region. > > > White cannot ally with either blue or red. But blue and red are not allies either and it could plausibly serve their purposes to have a semiautonomous buffer between them. Its alliance with a distant power increases its utility as a buffer. This little pocket of white poses no threat and will not allow either red or blue to use its lands as a Launchpad for military action against the other. [Answer] To begin, even with rivers linking the isolated state to the sea and a powerful navy, if your tech is medieval, this does almost no good. Land based fortifications in presumably Red state will prevent any type of supply using strictly rivers. Even a simple (defended) chain across the river was used for centuries to deny adverse ship traffic. Given your presented geographical constraints and military equality between the four states, I would say that there are three likely scenarios. First, and most likely for short periods of time, Peace will break out. No country is in a militarily advantageous position to do much of anything (except as Demigan pointed out, maybe Blue to invade Isolated, given some other constraints). Secondly, there will be periods of incrementalism in taking strategic territory. No one country can commit enough of its military strength against another country without some sort of tactical (incremental) or strategic (likely requiring something catastrophic to occur like widespread famine in one country) advantage. Maybe this is a military tech advancement which allows for force multiplication whereas Blue can divide its forces in such a way to invade say Orange but still maintain enough strength to defend against Red. The likely third component of this cycle will ultimately be some sort of military/political pacts or economic drivers. You mention it has been tried, but that is the situation at the beginning of your very dynamic scenario. Open warfare such as in the second point will drive necessity towards finding another advantage to even the odds, and this often times means asking for help. Even if these aren't fully blown alliances, non-agression pacts or mutual attack strategies where land is taken in geographically dispersed regions and kept by the attacking force, can quickly eliminate or nullify one of the nations. The above cycle will likely continue to play out, especially as technology advances unequally or catastrophic conditions create advantages for a well-placed and well-led side to exploit, allows it to. If holding on to the Isolated territory is enough a priority, you will likely need to make some sort of pact with at least one of Red or Blue. Or make it worth their while, say economically, to not invade and allow your forces to safely pass. Hope won't prove to be much of a strategy here. If you produce something unique to your peninsula which is needed by Red in their fight/defense against Blue, well, now you may have at least a bargaining chip for your relationship. [Answer] ## A few options 1. It was not like that in the Middle Ages. Nationalism only arose in the late Middle Ages / early Renaissance. There were many instances of small, isolated states, and they had complex webs of loyalties. Isolated Territory might be a vassal of State, yet still have alliances and obligations to the marcher lords of Blue and Red and be co-religionists with Orange. Only when everything breaks down do they go to war -- and even then, it is rarely a war of annihilation or conquest. Often, the loser just has to offer a suitable pay-off. 2. Consider Afghanistan: fairly weak country, surrounded by more powerful states, which generally maintained independence for most of its history due to a combination of extremely difficult terrain and having no resources worth the effort. 3. Economics: Isolated Territory might have economic value to Blue, Orange and Red that is only applicable when it is a territory of State. For example, it might possess a rare herb or mineral that can only be processed into valuable goods by the skilled artisans of the capital of State. B, O and R constantly scheme to find the secret, but until they do, it is more profitable to trade with White than to invade its territories. [Answer] The viable strategy is simply that if the eastern province is attacked, the western province attacks. Basically, the western forces act as a deterrent. You can't "stop" the attack in the east, but you, ideally, ensure that were it attacked, the price is higher than the gains. [Answer] **Fortify and Breed** Since we're in Medieval, terrain based fortification will be quite effective. While you've indicated that the smaller state could not survive a prolonged confrontation, the fact that the fortifications exist is a deterrent to confrontation. Especially when there are multiple countries of roughly equal strength. This is because the military advantage in the conflict between 4 warring states will go to the one who is the last to enter into battle, as they will have the numerical advantage after others have suffered losses. Encourage your people to have as many children as your production can support. Over time this will give you the best chance of success in the conflicts. **Lie** Not directly, but it'd be best if you tried to make the other countries think that your country has a secret alliance with another one (this should be considered as extremely likely since any two working together should be able to defeat the other two working independently). If they feel like their being baited into attacking, they probably won't. [Answer] If we discuss about war between countries over whole continent, it's more likely geo-politic strategy than pure war strategy. Let's look at the answers from Willk, ColonelPanic and Securiger (top at this moment). Both have paragraphs which related to geopolitics. Military maneuvers, army disposition, army structure and eventually war is only part of geopolitics. That's why my answer has little pure war options ## Territory exchange When I see *in the long run* I render it as *several decades, probably century*. It's extremely hard to control distant anclave not only during the war. Taxes, governor, communications are problems. Even language and culture will differ. So why White should hold anclave? The exchange could be not only by a treaty. White could evacuate all forces from anclave and conquer another territory which easy to defend ## Territory abandonment Sovereignty doesn't fall when first city has fallen. If anclave is just another province, then it's good idea to significantly reduce border line and abandon the anclave. If there is some unique resoucre and/or other **ultimate** need (say, the capital and governor is situated in anclave) then Red and Blue would have more reasons to conquer anclave. In extreme White could be considered as colonial country where big south part is colony which could be reduced/abandoned and most of the army is situated in 'anclave'. ## Losses during anclave conquest vs Benefits from it If anclave is a mountain region which easy to defend and it has no rare resources then both Red and Blue could select another targets which easier to attack. At the same time, Red need some guarantiees that Blue doesn't attack through anclave like Germany attacked France through [Belgium](https://en.wikipedia.org/wiki/Battle_of_Belgium). That guarantiees make sure Red forgo from preventive attack just to build up defence line. [Answer] Sorry, this isn’t really a complete answer, but may lead to one - others please feel free to flesh out the historical details. For historical examples, the most relevant would be to consider West Berlin. This lasted for 28 years, including 3 years of blockade. I suspect that key to the success of West Berlin was that the occupants strongly wanted to be identified with the West? Also relevant is how the British empire and others sustained distant territories, though I think they would largely have had direct naval access? [Answer] White should encourage decentralization within Red. Some effective strategies are: * Encourage Red to divide estates among sons, instead of practicing primogeniture. * Encourage Red's nobles to live in provincial towns, instead of riding circuits through their jurisdictions. According to *[Medieval Cities](https://rads.stackoverflow.com/amzn/click/com/B00PXHGZJA)*, this led to Italy having powerful city states instead of kingdoms. City states tend to remain smaller than kingdoms. * Contribute to endowments of a variety of colleges in Red's provincial cities. * Encourage each provincial college to teach in its local dialect. * Encourage Red to rely on tax farmers instead of a tax-collecting bureaucracy. This will allow White to maintain a multiplicity of routes through Red for its merchants and nobles to travel back-and-forth between the parts of White. [Answer] In my eyes it could work if the border between blue and red and red and orange was made up by a river that eventually starts in the isolated territory. Since all of the neighbours are hostile towards the state and they didn't ally to crush the state, I would assume, that they are also hostile towards each other. This scenario would be quite similiar to the world I am building and I have . The river doesn't flow through the territory of any of the neighbouring states it will be very hard for them to claim it for themselves and prevent a third party to use it, in example by building fortifications that control the river or start patroling it. This could be backed up by blue, that needs the river to actually get acces to the sea. But the real question is, why does your state need the isolated territory? There needs to be a reason why the state is undergoing so much troubles just to hold a bit of land. ]
[Question] [ I've always liked living spaceships, but it seems to me that the animal kingdom would make far inferior spaceships to the plant kingdom. With that in mind, what does this tree-ship have to be made from to: 1. Survive space itself. 2. Let humans live in interior passages. *Ignore everything else about trees in space (nutrients, air, etc.).* I'm only interested in the chemical makeup of the tree that will let it and its passengers survive things like extreme radiation and (in the case of the passengers) vacuum. If it helps when thinking about it, these trees evolved on a normal Earth-like planet, and were bioengineered to survive in space. [Answer] The vacuum of space probably isn't a problem. A layer of bark with tightly bound dead cells with thick cell walls would resist vacuum well, assuming it could be grown in a relatively uniform exterior layer. It would also be an excellent insulator, which would be a problem, the plant would need some method of shedding heat via radiators. There would be a need for some flex as there would be differential heating on the side exposed to sunlight. As you can read [here](https://asknature.org/strategy/bark-keeps-surface-cool-under-the-sun/#.WBH_pXn_phE) most bark is designed to regulate tree temp within an atmosphere, using air pockets, shadowy ridges, etc to circulate or trap air as necessary. But if the bark on the space plant is uniform in thickness and relatively smooth it ought to allow for vacuum protection and temperature insulation. Radiation protection would be another matter. The water content of the inner bark, plus perhaps heavy metals within the cellular structure, would be a good option to block solar radiation. Wood itself doesn't really block radiation, but with a high moisture content, thick enough walls, and perhaps water reservoirs in the wooden hull, it would suffice. You would need several FEET of water depth all around your hull to block a significant percentage of incoming gamma rays ([here is a nice technical article about it](http://www.eichrom.com/PDF/gamma-ray-attenuation-white-paper-by-d.m.-rev-4.pdf). Or you could construct a metallic inner hull for the human areas. Of course the tree itself would suffer radiation damage, unless it were grown and then killed, leaving just the wooden frame for the spaceship (which seems to negate the value of a living ship for self repair/additional growth, unless you just didn't have access to other construction materials). What you would need is a protected inner tree that continually regrows the inner and outer bark, which are the areas getting all the radiation damage. Kind of like skin, so long as the bottom cell layer is intact, the outer layers of skin can regenerate and heal quickly. There is a possibility of creating a [magnetic shield](http://www.islandone.org/Settlements/MagShield.html) for the ship, which would eliminate the need for a thick water logged hull, but that would also require a substantial non-organic component to the ship. There would have to be non-organic parts of the hull for sensors, access, and attachment points for whatever engine you are using. I doubt a tree could withstand much acceleration and the mass for strength ratio would be very unfavorable (especially with all that water) but if you had magic engine thrust tech, it may not matter. Otherwise a tree would be fine for a ship. Having interior passages and spaces with breathable air wouldn't be an issue, though obviously the living space/tree ratio would be low, much lower than in a conventional ship. But if the tree could handle life support and computational tasks, perhaps even sensory and drive management tasks, you could eliminate a lot of the space needed for equipment in a regular space craft. There could even be a symbiotic relationship with the humans onboard, the tree needs their CO2 and waste, they need the O2 and glucose. Not sure how well photosynthesis would function in a vacuum (regular leaves probably couldn't retain moisture) but that's out of the scope of your question. [Answer] Polymath [Freeman Dyson](https://infogalactic.com/info/Freeman_Dyson) came up with this idea as a means of colonizing comets with a minimum of machinery and investment. The [tree](https://infogalactic.com/info/Dyson_tree) roots itself in the comet and draws water and nutrients from the comet's core, and encloses the space around the comet in a shell of leaves and branches which are optimized to live in vacuum and collect the relatively weak sunlight available in the outer solar system. Due to the microgravity environment, there is really little limit to how large the tree could become. [![enter image description here](https://i.stack.imgur.com/Y8cMH.jpg)](https://i.stack.imgur.com/Y8cMH.jpg) *Dyson trees near Saturn* Humans and indeed an entire biosphere can live sheltered inside the tree trunks. If the foliage is dense enough and the genetic engineers have done their jobs, the leaves might form an impenetrable shell to keep an atmosphere inside between the canopy and the surface of the comet as well. This would make for a small colony capable of housing a few hundred humans and their associated biosphere. The wastes of the humans and any animals would fertilize the trees, and the trees in turn provide a breathable atmosphere, fruits and even (if carefully harvested) wood for building. Dyson tree colonies would most likely remain in orbits around the sun, since venting any of the cometary ices for thrust would be releasing critical supplies that keep the tree (and by extension, the people) alive. Under some circumstances, the leaves might be able to serve as a solar sail to provide some, very slow, movement across the solar system, but reflective leaves will not be available to harvest the sun's energy to support the tree's life processes, so the area of the canopy used to manoeuvre the tree would have to be carefully regulated. [![enter image description here](https://i.stack.imgur.com/AnAL6.jpg)](https://i.stack.imgur.com/AnAL6.jpg) *Dyson Tree. The vast canopy is needed to gather the very dim sunlight in the outer system, and too much of the surface devoted to reflective leaves might cause the tree to die* Living in such a colony would be akin to living inside a tropical or temperate rainforest, since everything between the canopy and the "ground" would be trunks and branches of the tree itself. Colonists would have to be well versed in arboriculture, in order to assure the health of the Dyson trees making up their world, and trade would be heavily tilted for the import of trace nutrients which are vital to the life cycle of the trees themselves. [Answer] Probably wood. Not necessarily maple, or oak, or whatever, but one that is much more dense and able to withstand significant pressure and impacts ([like this one on Earth, but stronger](https://en.wikipedia.org/wiki/Lignum_vitae)... that should be a good starting point to find chemical makeup and whatnot). The bark should also be quite strong, and should be less fragile than the trees we have on Earth. Under the assumption that this kind of tree would be able to withstand pressure and impacts, it would need a very high tolerance for radiation, or be able to very quickly heal itself from radiation damage (or, even better, feed off of it... some species of bacterium already do that on Earth, so translate it to a plant ability). To survive vacuum, it would (obviously) need to be air-tight. The problem with that arises in the form of "how do passengers get in and out of the spaceship?" If you had some kind of rigid-yet-malleable and very durable leaf-like growth from the tree that can be used as doors, that'd be best. Plants even have small openings they use to breathe that you could consider the doorways. [![enter image description here](https://i.stack.imgur.com/9AsI0.gif)](https://i.stack.imgur.com/9AsI0.gif) [Answer] There's one more important factor that is often overlooked: energy flow. To sustain life, you pump energy through the system, with energy exiting the system in less useful way. Take a look at this picture: [![ISS](https://i.stack.imgur.com/Up49v.jpg)](https://i.stack.imgur.com/Up49v.jpg) You can see solar panels, but there's actually more than that. Solar panels are ones that are sunlit - well, that's how they work. Dark panels placed to be not sunlit ever are radiators. They're as important to the ship as solar panels. If you simply place something in vacuum to harvest sunlight, it will get hotter and hotter - until it glows hot enough to lose as much heat as comes in (which, depending on distance to nearest sun, may vary wildly). Even if you don't harvest sunlight and only use energy you got stored in some way - guess where all those Watts go if you do, like, anything? They heat the ship up. Your ship must have means to lose excessive heat or everyone will be killed by heat as a byproduct of life support systems running - or simply by heat of their own bodies. If you have a ballpark estimate of energy flow through your system, [this](https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law) little formula will allow you to see how big/hot radiators you would need. Of course, you are not limited to radiators only. If you have a matter to spare, your ship could sweat with it - that would double as propellant, too! However, I'd suppose using pretty much the same design you'd use for your solar panels (leaves?) to use for radiators, too. Wasting matter is only a good idea if you have solid means of getting more. ]
[Question] [ Ever since the keyboard/mouse combo really took off in the early 80s there has really been no satisfying replacement since--at least for complex/precision tasks such as computer programming and graphic/industrial design. Often time computers in fiction are depicted with some kind of neural interface. While that seems like a cool idea, the mind is very impulsive, while you physical actions are obviously more deliberate. You often want to think something in your head before you actually do it--especially if your commands have real time consequences, like an air traffic controller for example (it's not all voice). I do occasional Python scripting which involves automating various from desktop software . It's relatively simple but I cannot comprehend any system that could allow me to replicate this work efficiently other than at least a keyboard. Will we still be programming on keyboards 200 years from now? Even if it is some kind of laser/hologram/augmented reality keyboard? Using your finger as a "pointer" seems like a logical replacement for a mouse but in no way is it able to match the precision of a mouse or trackball, etc. I'm probably just a product of my time, but I'm curious if other world builders have made any conclusions about this. And yes, this is probably slightly opinion based but not so much as that a logical hypothesis could not be reached. [Answer] I'm going to disagree with what seems to be the prevalent opinion: No, the keyboard will not become obsolete. The mouse, perhaps, but not the keyboard. It may change in its design (different material, different key placement, etc.), but as a big board of physical buttons, it is here to stay. Why? Well, what would have to change for a keyboard to become obsolete? There would have to be a simple way to enter complex data. This doesn't exist today; even if there were an interface today where I could simply think and the text writes itself on a screen, I would still program slower than I would with a keyboard, because thinking "for (int i = 0; i<=10; i++) {" is slower than typing it. "Right open parenthesis" is a lot longer to say or think than pressing shift and 9. That means there will have to be new programming languages that either use natural language, or some kind of "virtual code" utilizing pictures or other representative objects in a virtual world. While there are some non-language-based forms of programming out there, none have come close to eclipsing written languages today. The software and hardware to support this "virtual code" will have to be developed to the point where "virtual code" is better, faster, and cheaper than its predecessor, because otherwise, what's the point of switching? Even then, there will be programmers who will happily enter this virtual world and program themselves a "physical" keyboard. Remember, people still program in COBOL - just because a replacement exists, doesn't mean people will stop using it. Even a purely virtual world has a use for a keyboard. All that is a long, long way away, and as long as keyboards are cheap, intuitive, responsive, and touchable, I doubt that time will ever come. Keyboards may evolve, but they will never go away. [Answer] They're already going away. There are currently around 2 billion personal computers in the world (the kinds of things with keyboards and mice). In contrast, there are about 6 billion devices connected to the internet *not including personal computers*. Devices that don't have a keyboard and mouse outnumber those with by 3-to-1, and we haven't yet included computers that *don't* connect to the internet. Current examples of alternative methods of input for computers: * Video game controllers (which can even have well-designed alphanumeric input; see Steam Big Picture) * Your car's steering wheel and pedals * Everything you do on your smartphone * And tablet * Lots of custom inputs (e.g., coffee maker, refrigerator, Nest thermostat) * Voice (Siri, Cortana, Ok Google, Dragon) * Three dimensional holographic manipulation (consumer ready now? No. But I've seen the concept designs and prototypes, and it's pretty great) Okay, okay, you specifically asked about "complex/precision" tasks such as programming and graphic/industrial design. Graphic/industrial design is easy: you want a pen-enabled touch screen. A big one. Pens not only give you pixel-perfect precision, but removes the barrier of the mouse concept for a more direct interface. As a software engineer, I really can't imagine anything better than a keyboard and mouse for programming. That being said... I've been using them for so long, that at this point it's just a personal block I have. As an author, I can't imagine anything better than a keyboard and mouse for writing, yet Terry Pratchett wrote most of his final books with his voice. While it would certainly require a very special programming language and IDE, I could certainly see people using voice to program (other people, not me; I really can't get into voice controls for my GPS, let alone programming). But, about that mouse... I haven't seen a desktop computer in quite a while. And if we're talking laptops, pretty much all laptops come with either a touchpad or the "nubbin", and not a mouse, to control the on-screen pointer. Many people no longer bother with a proper mouse anymore. And if you're concerned about speed and precision with either of those, that just means you're not an expert in them; people who *do* use them exclusively are just as good as you are with a mouse. Some people don't even use mice. I've even heard arguments that the mouse/keyboard combination is slower than pure keyboard input (though I'm sure that's entirely dependent on the person). The most interesting barrier seems like it's going to be how to get large blocks of text accurately into a system. An argument *could* be made about the difficulty of speaking special characters for programming, but I don't believe that to be true. If we had, for instance, a pure voice method of programming, we would design programming languages conducive to that format. After all, if [Ook!](https://esolangs.org/wiki/Ook!) is a language... Anyway. Could voice replace hands for lengthy text inputs? It certainly seems possible. Speaking is something that basically everyone does, while keyboard use is driven entirely by technological restriction and necessity. As voice controls get better, fewer and fewer people will use keyboards (other than specialists). And once voice gets good enough, even the specialists will probably switch over. [Answer] ## Of course they will become outdated ### Limitations of Mouse and Keyboard as Input Systems Think about what the primary purpose of the keyboard and mouse are: It is to serve as a low-bandwidth intent-to-action converter (keyboards can accept about 500 keystrokes per second, but our own physical limitations mean the average input is far below that). The low-bandwidth can be partially mitigated by strategically designed shortcuts and symbolic logic -- witness an experienced programmer blasting through console commands, or a travel agency booking agent using those 'outdated' green screen at speeds GUI users could hardly dream of. The disadvantage is that any user who hopes to use the system must learn the symbolic logic, which can take a lot of effort. All that info has to be 'cached' in the user's mind. A mouse (and its touchscreen equivalent, the tap) goes the other way. The mental 'cache' goes away, and low-level widely-shared symbols, such as windows, icons, buttons and selectors take their place. This is still is another intent-to-action converter. The screen is a (one-way) high-ish bandwidth connection taking advantage of the fact that 20% of our brain processing power consumption is dedicated to visual signal processing. Megabyte one-way communication is useful, but a mouse is basically a binary selector -- I am interested in this area of the screen -- tap/click. All interaction has to be structured as a series of branching screens. Moreover, the megabyte connection overwhelms our (relatively limited) 8-bit or so attention channels - witness the difficulties in making websites and software useable, whereby useful information is often missed by users. ### A Path Forward If you think about it, human interaction with computers has moved through various stages of abstraction, as we have designed ways of interacting that are more and more human-cognition friendly. Initial communication with machines was at the 0/1 bit level, and this was so difficult that only math Ph.D.s could write compilable programs. This was replaced by machine language, printers, displays, programming languages and finally user interfaces. A ten-year old can now initialize a neural network by clicking a few buttons. How can machines get even better at reading human intent? I can think of two ways: ## The Butler Model ### Embedding machines into the fabric of our world. Effectively this provides the machines with a tremendous amount of information on our lives and wishes, in other words context, a "common sense" of sorts and makes them more likely to guess what we might want, given our prevalent conditions. > > Heart rate is irregular, such and such enzymes are building up, present user with this specially designed enzymatic drink to bring them back to nominal parameters. > > > It is 6pm, user is closing her drawing pad at work and wrapping her things, probably leaving for the home arcology --> call a vehicle. > > > --- ## Subconsciousness Model ### Embedding machines in ourselves -- mind-machine interfaces that read our intentions directly can then convert those "intents" into actual machine code, without any conscious direction by us. > > Alice sits in the middle of her virtual playground. The world shifts to become green and hilly. Streams erupt around the valleys, the world quickly adjusting to look as if the streams had eroded the valleys over centuries, plants shift to meet Alice's implied climatic preferences. A castle emerges in the distance, first with Disneyesque towers and crenels... Alice starts to frown ... and the castle shifts to a darker, gothic style. The sky darkens a little. Forests pop out in the mid-distance, and snow covered mountains become visible in the distance. > > > In orbit around Venus, Ahara decides to build a 100km habitation module, and spend a few days in the Venusian clouds. Her holovision creates a mockup, with the best guess of the machines often adjusted slightly by Ahara's thoughts. The machines take care of hull integrity, propulsion systems, optimizing across over 200 dimensions. As she thinks, the 3D printers create, dismantle and recreate the module live and so quickly that Ahara never bothers to think which parts are holovirtual and which real. Within minutes, Ahara climbs in and jumps into the Venusian inferno. > > > [Answer] If by keyboard you mean the standard QWERTY keyboard as found on contemporary machines, then sure, they'll change or fall out of favor. But if you mean using fingers to press keys or buttons as a way to input information, no. That's not going away. As long as human beings rely heavily on their hands and fingers to interact with their physical environment, some sort finger-pressing operation will be involved in almost all interactions with mechanisms. We don't use keyboards because nothing better has been invented yet, we use them because we have thousands of years of using our fingers to do almost everything that matters for our survival, and our bodies don't have any better, more efficient way to translate our thoughts into physical actions. Our brains are incredibly good at making our hands and fingers do complex tasks very quickly and with minimal physical and mental effort. [Answer] Im going to add something to the answer of Azuaron: You can see today a decrease in the market value of desktop pc's and laptops. A increase of other technologies will follow with the newest being VR Headsets that can be applied to practically anything, Now imagine a good vocal recognition software! You could do anything with those little headsets and the market is booming or is going to boom soon, the stats say so. If you look at the statistics of the market size of VR headsets you see a exponential increase until 2020. The technology isnt only interesting its also supported financially through many people. I think the mouse is going to become obsolete soon but the keyboard is, as Azuaron says, still very important. I program myself and a colleague here uses his mini 13'' without a mouse. The funy thing is, he is faster than most of the people I know. Eventually voice recognition will become just as useful as the keyboard. [Answer] I think the problem with many suggested improvements, like touch screens or mind-machine interface, is that they're more effortful than the status quo. And voice recognition? People talk too much anyway. The spoken word has a low degree of precision too. A high precision mouse allows you to move your hand very little to produce great change inside the computer... rather than throwing my hands all over a big screen to do the same thing. With a mind-reading machine you'd have to focus quite a lot on what it is you are doing, but with a little experience a mouse and keyboard become instinctive movement to translate your intent into action. And, importantly, you can be clicking away at whatever task while *thinking* about something else. That isn't something which can as easily be done with a mind-machine interface. What if you get distracted or are thinking about the next step? What I suggest is that we take the concept and improve on it in terms of precision, efficiency, and customisation. Replace the mouse and keyboard with holographic equivalents, which can be modified considerably for increased efficiency. Like, automatically scaling them for a person's hand and finger size and shape, and moving them closer to their body for ergonomic ease. Then you have the opportunity to interact with, let's call it a keysphere. You can design the holographic interface to be take advantage of 3D space and ergonomics far better than a flat board. The shape of the keyboard, and the exact gestures the mouse uses, can change to suit whatever objective. The mouse in this case becomes more flamboyant too, and may become more like a holding an imaginary ball and twitching it to do more complicated tasks at once. Plus more hygienic too - you're not touching anything! And let's not forget the pretty glowy holograms! Oooh. Holograms. [Answer] Well, as we change so do our tools. Going with this i believe that ,while we stick with our current media, we may be stuck with the mouse and keyboards. However,still we can change the designs of the keyboard. For example, take a flip phone, it has letters divvied up between 9-12 keys,and you press them a certain number of times depending on what you want to type. going with this, we could create something similar. If you created a 12 button keyboard, with only only 3 having functions other then letters, you could create something more efficent;it might look like this (excuse my terrible art-talents) [![thing](https://i.stack.imgur.com/xlJ8N.png)](https://i.stack.imgur.com/xlJ8N.png) The red keys would represent normal typing ,the yellow would sigal being done with a letter selection, the pink would be space, and the green would be tab/enter. thats all i got. [Answer] > > Will we still be programming on keyboards 200 years from now? > > > The real question is - Will we still be *programming* 200 years from now? Of course not. AI will be a stage where we ask a computer to program itself. It will act just like a human designer by finding out what we want, offering various alternatives and then producing the required result. *You: I'd like a bridge over the river please* *AI: Certainly just let me know where you want it and I'll get to work.* Later *AI: Which design do you like the look of?* *You: The one that looks like lace tracery would be great.* etc. --- Either that or civilisation hs collapsed and we're back to the stone age. [Answer] Quick answer - yes they'll go. Slow answer - can you imagine them still being a major means of digital interaction with whatever computers have reached in say, 300 years? I can't. A lot of the above answers seem to assume today's outlook - we are used to keyboards and they are useful for precision tasks. I think that, given another generation or so, especially one that takes better neural interaction in some form, for granted, and the effort and idea of typing *letter by letter* will be something quaint that only granddad's (and grandmums) do. [Answer] You think we will never develop direct neural interfaces??? For kingledion: You really think mice and keyboards would survive in a world where we have a direct mental connection to the computer? Why use the brain to command our hands to command a mechanical device to command the computer when the direct connection is better? The monkey equipped to directly command a robotic arm learned there was no need to move it's physical arm to command the robotic arm and quit doing so. Why would humans do it the hard way when the easy way is something a monkey can figure out on it's own? (The researchers set it up so the robotic arm would behave as the monkey's real arm, but the connection was in the brain, not in the arm. Even though they weren't intended to be separated the monkey figured out how to simply think at the robotic arm without moving the real one.) ]
[Question] [ Let's take a look at the [major cities of the world](https://en.wikipedia.org/wiki/Global_city): **Alpha++** 1. London 2. New York **Alpha+** 3. Tokyo 4. Hong Kong 5. Singapore 6. Shanghai 7. Sydney 8. Dubai 9. Beijing 10. Paris I'll point out features for a few of these > > **London:** Located on a major river with easy access to the North Atlantic > > > **New York**: Located on an enormous natural harbor with easy access to the North Atlantic and the Eastern Seaboard. > > > **Hong Kong and Singapore**: Deep natural harbors protected by their consitutent island chains, both on the Pacific, Singapore located between the Indian Ocean. > > > --- > > *Deterministic* most simply means given the same input, the same output always results. > > > **In other words, would the course of human history always end up making cities in these locations major world cities?** Or at least some near variant thereof? --- For example, if the Nazis had won WWII, Singapore would still have its natural advantages, and if the French had successfully colonized North America entirely, it's hard to imagine New York, given its harbor and placement for trans-Atlantic trade, would not grow as large as it has today. Even if the United States had nuked Tokyo, it would have sprung right back, look at Hiroshima and Nagasaki. --- A couple people have pointed out that the major cities of the world have changed over the course of history. This is, of course, true. I'm looking at a sampling of modern major cities, so the question is really about whether, in many alternate 2016s, major cities would always be in these locations. [Answer] **Not at all.** There are many places with these characteristics that do not have major city status and the elements that you have selected were often secondary. London is the city I know best so we'll use that as an example. Access to the North Atlantic: Completely irrelevant for the first 1500 years of the city's existence. Even when it became relevant, there were better ports to use, Bristol, Southampton, Liverpool. London was built for easy access to France and is the merger of the cities of London and Westminster (aka Ankh and Morpork). ## What you need to build a major city: Let's start with what you need to build a city at all: **Water** London sits on a massive underground fresh water reserves, it also has a lot of (mostly now underground) fresh water rivers running through. To make it a major city: **Communication, trade, transport.** For much of history these were the same thing. The only way to get anywhere was by sea, even until the industrial revolution, it was cheaper and easier to ship from Lisbon to Liverpool than to go overland from Liverpool to York. Trade and transport are still key, hence why the British Government is desperate to expand one of the London airports. **Make it your capital.** How many of the cities on your list are not the (state or) national capital? (Hong Kong is a special case, Shanghai was a different special case). People are attracted to the centres of power for whatever reason, once this has started it tends to continue. People go to where the jobs are, the jobs go to where the people are. Outside Dubai City, the rest of Dubai is a wasteland. The main reason London is a key global city is Empire. It was the centre of the world for a century. Capital of the last global empire. The wealth of the world passed through London, as did the people of the world. The city is built on that. It's not the best port, not the best harbour, it's not the best building land, most of the area close to the river is below high tide and marshland. The tide in the river flows too fast etc. **Political Will.** This is the difference between a merely big city and a major one. 4 of the cities in the top 10, [Hong Kong](https://en.wikipedia.org/wiki/British_Hong_Kong), [Singapore](https://en.wikipedia.org/wiki/History_of_Singapore), [Shanghai](https://en.wikipedia.org/wiki/History_of_Shanghai) and [Dubai](https://nextcity.org/daily/entry/how-dubai-became-dubai), were built by a government basically saying, "we want a major city, put it here". In these cases a small settlement or port already existed, but was expanded by political will. **In conclusion.** The factors you provide are required to make a great city, but they will not alone cause a great city to exist. [Answer] There is no definite answer, because we've never had an alternate history, only the one we have, but I'd risk a "no, it's not deterministic." There are certainly statistical commonalities between major cities. In particular, you'll see common patterns like the major cities forming in locations with good harbors, because good harbors are good for city making. However, it would be very surprising if human history had to always end up making all major cities in the same places. First off, that implies that "major city" has some fundamental underlying meaning, which it doesn't. Second, we can find easy reasons why this wouldn't be the case. While there are "good" places for cities to be founded, there are clearly more pressing concerns in the minds of a founder when they're planting their city. A city might move up or down the coast depending on factors. For example, if a neighboring country's borders pushed closer to a capitol city, it is highly likely that a different city would become the capitol of your nation. If a capitol moves, all sorts of commerce and government lines get redrawn, and different cities may be accentuated. I think a corollary to your claim would be to argue that a human being develops from a fetus to an adult in a deterministic fashion, which we know is patently false, and yet nearly every person you met has two eyes, a nose, walks on their legs rather than their arms, etc. Deterministic is a powerful word, and I just don't think it works out here. [Answer] # No. The question has a (somewhat arbitrary) list of cities which are important and prosperous *right now*. We have no reason to assume their prosperity will continue forever. We can see this by considering cities which have *stopped* being rich and important: * **Venice** was once the richest trading city in Europe, but now is of interest only as a tourist attraction. * **Istanbul** has an excellent natural harbour and strategic location. For centuries, it was the capital of the Byzantine (and later Ottoman) Empire and legendary for its wealth and culture. It is still the most important city in Turkey, but no longer one of the top handful in the world. * **Cairo** with its predecessor Memphis was one of the greatest cities in the world for centuries. Today it is large but poor and beset with problems. * **Baghdad** again was famous for its wealth, but it never really recovered from the Mongol sack of 1258. Needless to say, subsequent wars have not been kind to it. * **Buenos Aires** has a similar position to New York, at the mouth of a great river, but is not nearly as rich as it once was. All of these cities have natural advantages, particularly access to water in the form of a river, the sea, or both. This helped them rise to become rich and powerful, and remain at least somewhat important today, but it did not prevent them from falling. The reasons why these cities declined go far beyond the local geography; they include complex military, political, economic, and technological factors. There has been a world in which Istanbul/Constantinople was an "Alpha++" city; we know that from the history books. There is also a world where it is not; we know that because we live in it. There is no reason to suppose the cities listed by the question are any different. A thousand years ago, London was an unimportant backwater and Manhattan Island was a wilderness; a thousand years from now, they may be so again. [Answer] Not really, but it kind of will always look like it might. Cities are basically centers of logistics, in the broad sense that includes the dissemination and distribution of information and control as well as simply goods. As such they will invariably grow in places where logistics is practical and cities where the logistics is bad tend to not grow very large. Historically efficient logistics has meant water transport and cities have grown along coasts at places with natural harbours and along navigable rivers. Places where the two meet and transshipment from ships to barges happens have been prime locations for large cities. So places where you find large cities are fairly predictable. But if you step up from good location for cities and which cities have chances to grow "major" you'll find lots of variables. The obvious one is that trade routes are connections between supply and demand connected with the technology available within the political limitations of the time. Supply depends on natural resources and their development. It depends on locations of large centres of manufacture. What is manufactured and how and how well it can be transported depends on technologies available. Your city may have resources suitable for making excellent glass, but if the techniques required are unknown or nobody has figured the weird sand is valuable or somebody else already has the market, the growth potential will remain limited. Similarly unless there is population or industry that needs a resource being well positioned to supply it is not very useful. So the population and infrastructure at nearby areas is vital. This is really a major issue since population and infrastructure concentrate around cities, so interactions between cities are very important in which will grow really major. If a city nearby is already much large it will take unusual events to displace it as the major city of the area even if your location is now otherwise better. Similarly if there are no other large cities nearby, having good logistics is not that useful. Trade and industry will go to cities with larger markets. And the "nearby" is dependent on technology and politics. A person building a factory in South Korea because just to the North on the other side of the border there is population that has need for the product will probably be denied funding. Being on the Atlantic or Pacific was much less valuable before crossing oceans became reasonably safe and economically viable. It also naturally varies over time. When Rome was able to supply itself with food produced nearby building it away from the sea made sense. When it later grew large enough to require importation of food by ship, the city was not moved to the coast, nor did trade and population move to Ostia. And then there is the inconvenient fact that humans **change** geography to allow easier logistics. They make rivers more navigable and dig canals where no connection existed. They make artificial harbours of concrete where no natural harbour existed. They build roads and railroads to supply effective logistics where nothing natural existed. Many river valleys were converted from marshes or jungles to rich agricultural land supporting large populations along the rivers. Large water projects can turn deserts into something capable of supporting cities. So while you can say that major cities be themselves are "deterministic" the geography of transport routes, population, resources, and industry that determines which cities grow and which do not is dynamic, complex, and variable product of the past history and technological progress. This turned out to be fairly incoherent and rambling even by my standards. Hope it is still possible to determine what I was trying to say. Suggestions on fixes welcome. [Answer] I'd do this as a comment but I can't at this point, so I'll try to bring something more in the discussion. Human settlement are always built around three concepts : * Ease of defense * Easy of reach (includes waterway) * Close to an exploitable resource The first and third made for hard to develop township because the locations were often hard to reach, the best case being a combination of the second and third or of all the three. Then you need space around the settlement to develop. Later settlement like New York were built with different precondition than their earlier counterparts : the defense part was more manpower than strategical location, the ease of reach meant funnelling immigrants from oversea and with more modern transportation means, the exploitation sites got closer. You can say that the location of cities *used to be deterministic*, in that the location of the settlements were chosen on similar criteria for similar results. Now, with modern technologies, you can settle on a plain in the middle of nowhere and build the needed defense and road (train, plane,...) network to get close to your resources then start a flourishing town out of nothing, for no other reason than "you can". You'd need some good PR people and huge assets, but it could work. Of course, one might wonder why you'd do that... [Answer] ### Yes, there is a deterministic factor. but, ### No, they would not always end up becoming major world cities. ### The deterministic factor of becoming major world cities is **economic importance**, given enough economic importance as input, every city could become major city. But economic importance changes overtime due to many complicated reasons. For example, the city with highest economic importance in West Asia was once *Baghdad*. However, this later change to *Istanbul*, and now it is *Dubai*. However, *Istanbul* is trying to change its position in recent years as being the bridge between Europe and Asia. ### The only reason that many major city is near coastline or river is simply because waterway promotes trading, so it could easily gain economic importance, but this is not always the case. For example, inland *Mecca* is on land trading route, so it gains economic importance. Inland *Tehran* is the hub of Iran, so it gains economic importance. ### However those cities usually have great transport network. ### Countries tend to send their economic hub as capital, but again this is not always the case. *Sydney, New York, Istanbul* are examples, the capital is *Canberra, Washington Dc, Ankara* ### All cities on the list (except Dubai and Beijing) have well developed financial market and exchange to gain economic importance **London** has London Stock Exchange and London Metal Exchange **New York** has NYSE and NASDAQ **Tokyo** has Tokyo Stock Exchange **Hong Kong** has Hong Kong Stock Exchange **Singapore** has Singapore Exchange Limited **Shanghai** has Shanghai Stock Exchange **Syndey** has Australian Securities Exchange **Paris** has Euronext Paris ]
[Question] [ In many cultures I have seen in the world circular currency was what they used in medieval times. I have seen very few cultures that used rectangular currency even for a short period of time. The question here: is there a reason that so many cultures used primarily circular currency? And is there a reason why rectangular currency wasn't more popular? Keep in mind I am talking about the medieval times. [Answer] To put it plainly, **round coins just seem easier to make and work with**. Because casting is a pretty complicated and energy-intensive process, coins would usually be stamped instead. I have here a [period illustration of mediaeval minting](https://commons.wikimedia.org/wiki/File:Freska_v_chr%C3%A1mu_sv._Barbory(Kutn%C3%A1_Hora)_1.JPG) from the church of St. Barbara in Kutná Hora. What you see on the bottom two pictures is the forming of the blank and stamping of the coin, respectively; The blanks were cut out of a hammered rectangular sheet of silver by the expedient of holding the sheet over the edge of an anvil and striking it with a hammer (bottom left). This would initially produce smaller rectangles; their corners would then be cut off in the same fashion to produce a round blank. On the right, the mintmaster is stamping the coin. The (steel) stamp has two parts, both negative; one attached to the anvil below, and the other on a hammer-like object held at the top. The top would be struck with a hammer - you had to do exactly one powerful strike to get a clear imprint. The reason why round currency was preferred likely have to do with the stamping; it is easier to line up round stamps than rectangular ones (if you misalign them, the images on the rub and the obverse will be slightly rotated relative to each other, but edges are still in the right place), as it is also easier to make them (nice and crisp rectangles are pretty finicky to forge). Additionally, there is something to be said for the coins not having sharp corners. Individually (or even put together), **none of these factors disqualify rectangular coins from existing** - indeed, we have examples both from the Orient and from [Europe (namely Transylavnia)](http://www.fleur-de-coin.com/images/articles/trans2taler.jpg) - but at the end of the day, **round coins are just so much more convenient**. [Answer] Adding to the already good answers, I'd like to toss in a little bit of physics. As mentioned, coins during the Medieval period were generally hammered/stamped (casting wasn't common because it's harder to do accurately with dense materials such as metal). When hammering something, force is distributed radially out from the center of impact, which lends itself naturally to a round shape. Think of a wad of dough being smashed under a board: The dough will ultimately come out with rounded edges, even if it starts out roughly square to begin with. Corners are simply harder to manufacture through this process, they're much easier when cutting, as in paper money, which [didn't exist in Europe at the time](http://www.wikiwand.com/en/Banknote#/History). Note that paper money [did exist in parts of Asia](http://www.wikiwand.com/en/Banknote#/Early_Chinese_paper_money) as early as ~700CE, and in those cases it *was* square, probably because cutting straight lines is easier than cutting curved ones. [Answer] I think the way money was done is the answer. I really can't translate all the specific words in English, but check [Wikipedia](https://en.wikipedia.org/wiki/Hammered_coinage). A smooth rectangular coin is more difficult to make. Medieval money was not very regular with round hammers smashing a piece of metal (I hope that's the good word) but the strength applied on metal by a rectangular hammer would have been irregular and the coins would not have had straight sides. They would have look like a melted pat of butter, unless a big work of carving the sides is done after hammering coins. The weight of a coin was the best way to prove it was not false, so carving the edges to make them smooth and straight would have lightened the final coin. [Answer] Multiple reasons: * **in the middle ages, money was [commodity money](https://en.wikipedia.org/wiki/Commodity_money)** i.e. gold/silver/bronze coin whose value was the actual value of the coin. Over the 16th-19th centuries, the world moved to **paper money** (still generally backed by hard assets e.g. gold and silver reserves), and then fiat money * the main considerations for making commodity-money coins from precious metals (or an alloy of) are a process that doesn't waste metal, cannot be counterfeited (e.g. coating or alloying with lead). Round coins are easy to stamp and and round edges easy to mill/finish; we can melt the wastage. No advantage to a rectangle or polygon, and corners would snag or damage a purse. * the main considerations for making paper money are something light, strong, tough, convenient to carry, cannot easily be defaced or altered, and again cannot be counterfeited (in modern technologies, i.e. inks, color security patterns, foil strips, translucent watermarks). Something square/rectangular allows it to be printed without waste. Triangular corners would dog-ear. Now **why rectangular?** Per [Why are banknotes rectangular](https://www.quora.com/Why-are-banknotes-rectangular), we want something that can be easily stacked, bundled, counted etc. Rectangular beats square because it self-orients: there are only two possible ways to orient it, and the pictures and text very quickly tell us when we've got it upside-down. You can quickly count the number of bills in a stack by riffling through them. The long-side allows you to print dates, serial numbers, name of issuer etc. Rectangular also beats square in volume-efficiency: they can be folded and kept in a wallet. * the answer is not due to technological impossibility, as I first expected: in China the [Tang Dynasty pioneered block-printed paper banknotes since 740](http://fourriverscharter.org/projects/Inventions/pages/china_papermoney.htm) with inks and anticounterfeiting; until [13th-C devaluation under the Mongol dynasty](https://en.wikipedia.org/wiki/History_of_Chinese_currency#Mongol). The printing press was invented 1410. * (there was legitimate resistance in switching from commodity money to paper notes in the 17th-18th centuries, and not even primarily due to counterfeiting [A History of Printed Money](https://www.theibns.org/joomla/index.php?option=com_content&view=article&id=251&limitstart=3). Citizens would distrust that the note would be redeemable by its issuer for face value, due to inflation, wars etc. Some governments could and would literally print more banknotes, which meant your notes could always be devalued and were only as strong as the reputation for fiscal restraint of the govt that issued them. That addresses why (rectangular) paper money didn't become popular.) * so why was China 900 years ahead compared to Europe (first European banknote: Sweden 1601)? My instinct is it was **lack of stability: the absence of a lasting strong central govt guaranteeing notes with hard assets through all crises, invasions, wars, asset seizures**, of which medieval Europe had lots. I think it's no coincidence that European paper money only became accepted after the end of [the European Wars of Religion (1648 Peace of Westphalia)](https://en.wikipedia.org/wiki/European_wars_of_religion) when European countries largely agreed to stop invading each other. Also, the Age of Discovery had started, and it was more profitable and less political blowback (in Europe) for European powers to attack each others' New-World colonies and shipments. It would be good to quantify all this. (Another asking: <https://www.cointalk.com/threads/why-are-most-banknotes-rectangle-in-shape.536/>) [Answer] Aside from all of the good answer given here but can you imagine trying to pull rectangles out of a pouch or pocket? The corners would catch on everything. Also, what is the coin worth if the corner broke off? [Answer] I have a different opinion, mostly based on school lessons. I'm not sure if it's totally wrong or right, it's just another point of view. At the beginning, commodity money **was** rectangular. Larger denominations of money like [grivna](https://en.wikipedia.org/wiki/Grivna) could be in the form of a stick. ![grivnaImg](https://upload.wikimedia.org/wikipedia/commons/thumb/2/21/Grivny.jpg/1920px-Grivny.jpg) Early coins were made from precious metals and their value was based on their weight, so their form or shape was not as important. ![](https://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Denga_moskovskaya_coins_%281480s%2C_Kremlin_museums%29_by_shakko.jpg/1024px-Denga_moskovskaya_coins_%281480s%2C_Kremlin_museums%29_by_shakko.jpg) Since weight was important for determining the value of the currency, one issue was [coin debasement](https://en.wikipedia.org/wiki/Methods_of_coin_debasement). It's easy to cut a piece from a rectangular coin so that nobody would notice. ]
[Question] [ Something I realized not too long ago about a spacefaring society is that while a lot of technology is going to feel advanced, a lot more is going to feel ancient just because of all the hurdles it has to overcome in order to work in the first place. One example of this is communication. The way I'm currently explaining it in my world is that in order to travel faster than light, your ship has to go into quickspace (hyperspace, slipspace, you know, that alternate dimension where physics lets us do whatever we want). Quickspace works a lot like an ocean, where there are currents and winds that can either help or hinder a ship as it travels. The thing is, in order to use quickspace, you need a viable method to enter and exit it (otherwise, you're pretty much stuck there for good). This means that a signal sent through quickspace will go way faster than any ship, but it's never going to know when or where to stop unless it's contained within some sort of ship capable of pulling it back into realspace. This means that information travels only as fast as ships do, and we're talking anywhere from days to years for intersolar travel. So, then, my question is how would our modern communication systems adapt to handle this lag? Considerations for how news/messages travelled across oceans in the past would be great, but I'm also concerned about how we deal with things like the Internet with an average ping of a couple months. [Answer] Actually, even with contemporary communication protocols today, latency is not really an issue as long as the link is reasonably reliable. This is a [delay-tolerant network](https://en.wikipedia.org/wiki/Delay-tolerant_networking). Note that in the real world, with long-range communications you are going to have to add a good chunk of [forward error correction](https://en.wikipedia.org/wiki/Forward_error_correction) so that the majority of errors can be repaired without requiring re-requests and retransmission of the data. There was even an Internet Draft published some years ago that discussed how an "interplanetary Internet" could function. I would have to go and dig it out, which I am not terribly inclined to do at the moment, but the gist was that yes, it would work quite well with only minor alterations to the low-level protocols. IP would be fine. UDP, ICMP and friends wouldn't fare too poorly. TCP wouldn't do great in a high-latency environment with its roundtrips, but that wouldn't necessarily be a showstopper if the latency can be kept to a reasonable level (think perhaps minutes; the limiting factor would probably be a combination of how long you're willing to wait, and your ability to track both endpoints in space). The real killer was when you started applying the high latency to higher-level protocols, and contemporary implementations of those. Something like plain HTTP, with a single request followed by its associated response, wouldn't be too bad. A protocol designed to be used interactively, like FTP or SMTP, however would not work very well as currently designed because the latency would be multiplied by the number of roundtrips. DNS would definitely have problems because it is relatively latency-sensitive. This is not an insurmountable problem, but it is something some of our current protocols are not well equipped to handle being designed for an environment where a latency of one second is extremely high. Since this I-D was written in the context of our real world, with our real world physics, they also had to deal with the fact that not all nodes would be visible (radio link wise) from all other nodes, or even any given nearby node, at all times. So how do you solve all this? Well, it turns out an easy solution is to design a network using # store and forward [Store-and-forward](https://en.wikipedia.org/wiki/Store_and_forward) is a very old technique for building computer networks. Technically at some level all switched or routed networks are store-and-forward, but the forwarding is done so quickly we don't normally think of them as such. In a real store-and-forward network, you may hold on to packets for hours or days until they can be transmitted to the next node, bringing them closer to the destination endpoint. For two examples of store-and-forward networks, consider [Usenet](https://en.wikipedia.org/wiki/Usenet) and [FidoNet](https://en.wikipedia.org/wiki/FidoNet). Internet e-mail also used to work in the same manner. Store-and-forward networks do not provide real-time communication services, but lend themselves very well to batch- and message-oriented communications. E-mail (both personal as well as in the form of discussions) works well in such a network. Web browsing as we know it wouldn't work as well, simply because of the delays involved, but there is nothing *in principle* that prevents it from working. Delivering batch requests to be processed and the results later returned works fine. And so on. **So you'd have to design your communications systems to account for this latency.** That means no video screen showing a faraway higher-ranking commander for a two-way chat. Depending on how much bandwidth you have and the needs of the story, you could either have audiovisual, just audio, or just text, with or without separate channels for data for computers to process. Just text is where it would most likely start out, since that requires by far the least bandwidth (and as an added bonus is possible to skim through and get the general gist of, unlike a video message which must be played back at normal speed). It also means communications more like e-mail or perhaps even postal letter, or something like what we're doing right here on Stack Exchange with the question and answers format, and much less like a telephone conversation. **The actual data** could then be carried by specialized vessels, or piggybacked on ships already enroute to the destination area, or carried through a quickspace network like someone mentioned and carried into normal space near the endpoint. But the above allows you to deal with the latency introduced by the fact that the message must be *carried* somehow. [Answer] What about having comm stations inside quickspace? So you send a bunch of them into quickspace, create a network of communication and when you need to send a message, you'll send it to that network, the message's data will contain the coordinates of it's destination and once it reaches the closest comm station within QS that can send it out into normal space, it does. Yes, there is the obvious issue of wanting to send a message further than what the QS comm network can reach. In that case the message would travel faster than light up to one point and then it would continue going through normal space at the speed of light until reaching it's destination. [Answer] **Pony express** Information is uploaded to high capacity media with high speed read and write (SSD disk could be great example of this) and then sent via ship to its final destination. There would be small (one person?) ships designed for speed. Fun side note. Even nowadays [it is faster to send information via post than via internet](https://what-if.xkcd.com/31/) **Tube post** Lets go even smaller: Have a fully automated capsule programmed to go directly from point A to point B. That ship would probably consist only of: * A computer able to go only from point A to point B through quickspace (the smaller, the better) * Quickspace drive just big enough to get you from A to B (getting the hint?) * Payload, aka the SSD disc (or anything with really high speed read and write access) * Fuel (I dont have to specify how much you need, right?) Basically, the setup you would go this way: 1. Pony express companies would arise. Small ships would take care of sending information from there to here and back 2. Someone would work hard on automating the whole process as much as possible. The smaller, the better (tube post) 3. Add accuracy to tube post. Whoever can manage the tube to re-enter into normal space at *exactly given point* wins 4. Outposts arise. You would send tube post to well connected centers of information [Answer] I'm going to make a few suppositions, the first is that you can send a signal in the Quickspace even if can't leave. 2nd you have some ability to direct the signal, since you can direct a ship. So What I would expect to speed up communication would be to have relay stations, some permanently in the Quickspace boosting and relaying messages like a router and at end points machines that can pop in and out of quickspace to send/receive messages from real space. It might be cost prohibitive to use it to call family every night but it would allow much better and faster communications. There will still likely be lag, but it will be much more manageable. However, the lag will be the primary restriction on how far 'Earth' could extend it's influence to other colonies. The farther away less, and the less the colony needs anything from earth or other systems it will also reduce their need to appease. But for how the average person would handle the lag look back to the US and Europe and the rest of the world through the 19th century until the telegraph started connecting the world. [Answer] It's a little bit frivolous, but high latency 'internet' has been tried - the protocols support very high latencies, although you do have a pretty fundamental problem with retransmission and error correction. <http://en.wikipedia.org/wiki/IP_over_Avian_Carriers> But pretty fundamentally - the internet protocols as they exist have reliability and retransmission built in. That's just horrible when you've got high latency burst communications. What I'd imagine you'd get instead is basically what we have with email - email was designed for an era when the average user dialed up to a local point of presence via a modem. Internet comms weren't 'always on' for businesses either. You send your mail to a local gateway, and it'd attempt to deliver later. This would work in your scenario. Electronic mail packets containing emails being shipped back and forth. You may also want to look at older protocols like Archie, Gopher and NNTP as well. These are also from an era of 'not always on'. I think what you'd end up with is multiple similar, replicated and synchronised internets. Maybe you'd ship a large 'internet backup' back and forth on each courier, and resync the differences between each, sort of like rsync would. [Answer] Another solution (which also breaks laws of physics, but in a different way) is something like [Ansible](http://en.wikipedia.org/wiki/Ansible) instantaneous or superluminal communication. To make it more limited, make it that every pair of ansibles can communicate only with each other (coupled quantum atoms or similar handwavium), so to talk to 1000 different world you need 1000 ansibles. Yes, a hassle, but certainly worth it. [Answer] The RPG Traveller (1st edition in 1977) has a communications model for interstellar communication - **The Express Boat Network.** <http://wiki.travellerrpg.com/Express_Boat_Network> > > The express boat (also called an xboat) is a small, fast ship filled > with a pilot compartment, message data banks, and jump drives. The fit > is so tight that there is no room even for maneuver drives. Each is > capable of jump-4 (four parsecs per week); it jumps, relays its > messages to the station on arrival, and then waits to be picked up by > a tender, to be refueled and sent on its way with a new load of > messages. The local station, meanwhile, accepts messages, encodes > them, and transmits them to a tender at the edges of the stellar > system. Messages brought by the arriving xboat and intended for > further down the line are consolidated with the new data and all are > sent on to another xboat already fueled and standing ready to leave. > The entire network operates like the pony express — messages are > always moving at top speed. Transfer time for messages from one xboat > to another can be as short as ten minutes, and is rarely more than an > hour. > > > Note: a *jump* in the Traveller setting takes one week, regardless of jump length. ]
[Question] [ I'm writing a sci-fi book where the main method of travel involves collapsing a star into a black hole by putting a satellite equipped with some sort of handwaving mechanism into orbit around the star. The satellite can then direct a beam of energy with a cross-sectional area the size of the black hole itself (ex. our Sun's Schwarzchild radius is just shy of three kilometers, so that would be the radius of the beam created out of a black hole from the Sun). Once the spacecraft enters the beam, it enters a "free-fall" accelerating at about 51 G, to a maximum speed of about 10 000 c. The satellite can send messages to the spacecraft instantaneously at any point along the beam, but the spacecraft can't communicate back - only receive. A property of this beam that I'm bringing into the story is that the process of traversing the boundary in or out triggers a massive EMP that fries anything electronic on-board. The satellite observes the EMP from its orbit and calculates the time at which the spacecraft must exit the beam to reach the next system, and communicates this to them. Because of this, the engineers on-board the ship have to repair the communications array after every entry and exit of the beam. For the same reason, physical mechanisms for basic things like life support, lighting, etc. are highly preferred. Transit time in the beam (and therefore maximum time to fix the communications array) varies, but would typically be a month or so at most. My question is whether, after leaving the beam in the new star system probably up to as far as a few AU away from the star, **what would be the bare minimum of electronic components related to the calculations needed to plan the burn length, timing, thrust, etc. and control for these mechanisms that would need to be repaired/replaced to be able to accurately deploy the satellite into a near-zero-eccentricity orbit within 0.1 AU?** Bear in mind that these missions are decades long with dozens if not hundreds of jumps, and new resources would need to be acquired from each successive system (ex. chemical rocket fuel extracted from a gas giant or from the star itself prior to collapsing it, minerals from asteroids or rocky planets, etc.). EDIT: Have accepted an answer from @Starfish Prime, but received lots of good suggestions in comments as well. I am now aware of the issue with EMPs injuring humans as well, so will be modifying the mechanism accordingly. [Answer] Electronics isn't the only way to do digital computation, you know. [Fluidics](https://en.wikipedia.org/wiki/Fluidics) is a particularly robust alternative, though not necessarily very fast or compact... clock speeds might only be in kHz at best, so it would be outperformed in terms of raw speed by something like the Apollo guidance computer. Have a read of [A brief history of liquid computers](https://royalsocietypublishing.org/doi/10.1098/rstb.2018.0372). Fluidic amplifiers allow a small, low-pressure fluidic logic system to control much larger, higher pressure systems, so your control logic can interface with big stuff to make your spaceship work. The systems can be pressurized using a pump driven using a something like a sterling engine warmed by a nuclear heat source... perhaps an [RTG](https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator), but a whole fission reactor isn't out of the question, the operation of which a fluidic computer would be ideally suited, being quite resistant to radiation (*System Shock 2* has a fluidic system that handles radioactive stuff, though I don't think it went into detail of what it was, or what it did). You don't have to have power-generating equipment attached to a reactor, so it could be quite EMP-proof. This seems like a sensible basis for running life support, too. For something a bit faster though, how about "[phononics](https://en.wikipedia.org/wiki/Phonon)"? [Phononic computers](https://phys.org/news/2007-11-phononic.pdf) might be run on waste heat, perhaps from the same nuclear heat source that drives the fluidic minimal support systems. The *Orion's Arm* setting had "[ultimate chips](https://www.orionsarm.com/eg-article/48507b746e356)" using phononic computation, though I don't recall coming across it in other scifi works. I don't see why a phononic system couldn't interface with a fluidic system, using the latter to do the actual heavy lifting whilst the phononics does the important thinking. ([Photonics](https://en.wikipedia.org/wiki/Photonics) also exists of course, but I think it has too many points of contact with electric systems to be guaranteed to work under the circumstances, but stuff like [plasmonics](https://en.wikipedia.org/wiki/Plasmonics) and [polaritonics](https://en.wikipedia.org/wiki/Polaritonics) not only sound awesome but present the possibilty of very fast, if not necessarily very compact, digital computation. Interfacing with external systems in the absense of electrics might be difficult, but it might work using fluidics again and [chemical lasers](https://en.wikipedia.org/wiki/Chemical_laser) might bootstrap your optical systems until you've got electrics up and running...) And it can only get weirder. [Belousov–Zhabotinsky computers](https://en.wikipedia.org/wiki/Chemical_computer) anyone? Running on chemical reactions? No? Your EMP effect apparently doesn't frazzle the meatbags on the ship, so *neural* computation clearly isn't out of the question... lab grown neural tissue and musculature to operate valves and control rods to fly the ship. Organic bioreactors to brew up fresh replacements to deal with attrition. Maybe not even artificial, but cunningly adapted and modified living organisms, with a big of clever genetic engineering and surgery. Finally a justification for living, at least partially organic (cybernetic!) spacecraft. Peter Watts called his take on neural computers "smart gels" (or informally, "brain cheeses") in his *Rifters* books ([free to read on the author's website](https://rifters.com/real/STARFISH.htm)), and whilst he had electronic interfaces for his creations, you can now see that there's no reason to be limited by that. --- The big question I guess is the nature of the EMP... remember that a severe enough electrical disruption can work on meatbags, too. Careful construction of the ship could minimize the number of long metal conductors which link to any electronics, and if the electronics themselves are disconnected and sealed in Faraday cages prior to the "jump" they should be safe. I get the impression though that you don't just want a system where you unbox a perfectly working set of electronics after each jump and carry on business as usual, and that means your EMP is going to be kinda magic, and as such giving any more useful insight is basically impossible because that's the nature of magic. [Answer] If physical space on board is not at a premium - then this could be done with an Analogue computer: [Iowa Class Fire Control Computer](https://www.youtube.com/watch?v=gwf5mAlI7Ug) Now - granted, this is for a firing solution, but your basic functions of Pi, Reciprocals, Addition and subtraction, multipliers etc. are all there. If it's sole purpose is to calculate orbits, then with a sufficiently precision machined components - perfectly doable. Of course, the accuracy of the output will be largely determined by the accuracy of your inputs such as: * Mass of the body you are orbiting (or the gravity of the body you are orbiting) * Mass of the object. * Initial velocity. * Desired orbital height. etc. Some of those could be manually input (e.g. desired height) the rest could be fed from an analogue source continually (if you really want to go old-school) [Answer] You can use conventional electronics, but you would probably have to out it into some shielded mode before the EMP. If you don't know exactly when it might happen, you may have several computers, some running and some not. The crudest from of 'shielded mode' might be sticking everything in a Faraday cage. A better version might be to separate the memory and processing chips from their motherboard, so there are no long lengths of wire next to the sensitive components. The smaller the components are, the less EMP they should pick up. However, it talks less EMP to destroy a small component. One of the places I used to work had an EMP testing rig outside my widow. They put armoured vehicles into it and tried to toast the electronics. I imagine the EMP you are thinking about may be considerably larger than the sort of thing they were testing, but if people survive, then a computer probably can with the right precautions. [Answer] There is no need to have digital computers on board of the rockets and spacecraft, and the first pre-1960 year rockets likely did not. [Here](http://astronautix.com/r/r-7.html) is quite detailed description of R-7 that started as a ballistic nuclear missile but later made basis for first Sputnik I launcher and many later flights. If any computer would be present, I assume should have been mentioned. [Here](https://naukatehnika.com/velikolepnaya-semerka.html) is even more detailed explanation about this rocket (in Russian), no computer mentioned. All that digital computers could provide can be achieved with the help of calculations that have been carefully prepared on the ground and pre-set timers (when to fire the engines and for how long). If alterations are needed, the pilot can receive instructions from the ground over the radio that also does not need to be digital. ]
[Question] [ The species in question that can survive in the vacuum of space for extended periods of time (say months). They can feed on stellar radiation and have an innate sense of orbital dynamics. They come from a planet with several moons and they frequently travel from the planet to the moons and back, and occasionally venture out to other planets. The planet has similar gravity to Earth. Moving in space seems somewhat plausible. They could use thin membranes as solar sails and bladders of gas for maneuvering. **How do they get into orbit?** I'm looking for a mechanism that is primarily biological rather than technological. I recognize that the line is fuzzy, so the main criteria I'm looking for is that one of these animals could make it happen purely of their own means, without assistance from any others. Beavers can make a lodge, but each one can do it by their own power without reliance on the work of other beavers, so I'd count this as biological. Bees making a hive takes a lot of bees to do and no single bee can reasonably do it by itself; this, I'd classify as the lowest threshold of technological. A human making fire with a bow drill that they can make themselves out of materials in nature is grey area; they need knowledge passed on by other people, but otherwise can do it of their own means. If the planet needs to be substantially less massive that Earth to make this possible, that's an option, but the closer to Earth's gravity, the better. **Clarifications:** * The organism should be big enough to be visible unaided, but beyond that is whatever size makes this plausible. * The entire organism does not need to make it into space (and it seems unlikely that this would happen). All that needs to happen is an egg, seed, or larva capable of growing a new organism makes it into space. * A given member of this species does not need to make this trip multiple times in a lifetime, and the trip to space could definitely be part of a very specific lifecycle phase (like Salmon spawning, only much more extreme). * The organism does not need to be an animal. If there's going to be a lot of photosynthesizing or if it would need to have a large stationary component, it could be a plant. [Answer] Bordering on plagiarism, borrowing from Larry Niven's [stage trees](https://larryniven.fandom.com/wiki/Stage_Tree#:%7E:text=The%20stage%20tree%20is%20a,cross%20between%20moss%20and%20wool.) the creatures while immobile while landed could have further adaptations to its canopy to allow its foliage to fold away at launch, then deploy again in a way to act as a solar sail. It could even exist as an ocean living organism that launches from the water. There are any number of possibilities from the basic idea. [Answer] Nice, you know your shortcomings, nice definition of what passes and what's not. While it probably possible to imagine a creature which can do as you want - hop from a gravity well to space periodically, doubt it can do it frequently however, as even few times is somewhat an achievement. We may probably imagine them being able to produce carbon nanotubes natively, as part of their tissue, 100GPa tensile strength and thus being able to accumulate required energy over time and then use atmosphere gas and (or) water to propel themselfs like a typical rocket. Or even rocketfuel, without cryo to it, and be in essence a rocket. However it probably just a good(or not, taste preferences) handwavium More realistically, on the border of handwavium it can be a part of some maturity metamorphosis, when a bigger body shoots out its part(s) in to the space. There are real proposals of gun like solutions which should be capable to shoot a ton or so in to space, and it looks viable. But sure mass of the gun and mass of a projectile - one is much bigger than another, but there is a certain simplicity to installation, it just long, km's long. * km size organisms are not common, but some forests are one tree actually(or something close to that), so not impossible. So some photosyntetic organism, without necessity to move that much, maybe, but not only. And those guys, which are shot to orbit, they do not travel that much of the orbit of the planet, they hunt for those spores to grow, and that this bigger ground body lives by itself long enough to shoot many of those projectiles, with nanotubes and such it may endure more than one shot, plus healing, and other ways, etc. Projectiles, those shoots, are some sort of spore witn a shell, so as it is food for those in orbit, so as it can become some sort of parasite, which sticks to already grown thing in an attempt to consume it, and some times it just kills kessler syndrome like or just by a collision. So when they grow enough, those who survived it all and were in luck they may choose to get to higher orbits, to avoid being shot by a parasite thing or collide with others, and maybe later they evolve in something which travels a little bit more. Ecosystem of those wont't be so chil, as you seems anticipate, it will be harsh bloody massacre in slowmo over 1000's of years, a blood bath from which rare surviviors will emerge and wander off. The thing will evolve sloow, but it can be engineered. So situtation can be quite complex. So easier it is to handwave the first option. So while it is not impossible to imagine such thing, hard to anticipate it to evolve, but who knows who knows, and I guess there is a chance to make such thing to be. PS more like comment answersince I can't comment due wb javascript updates. ## PPS * *"can be a part of some maturity metamorphosis" whichever way you do it (gun or rocket) it necessarily loses a large portion of its mass with every ascent into orbit and beyond .. so one way or another whatever method is chosen it can probably be viewed as this to some degree, it's going to require a long growth period to replace the parts used for each launch whichever way you go .. if the OP was using a smaller gravity well things could be different.* – @Pelinore About how long it takes to recharge. Due the size, photosyntesis is the most likely as an option, not necessarly the only one, especially if we talk about artificial creature, but for evolved one it is a most likely option. In earth conditions, 100x100m plot of land can bring about 2 tonnes of fuel, in form of grass itself, so if we wanna some juice from them it will be less. So, the thing grows some sort of "limbs" getting 2t of fuel per season is optimistic scenario. And so for "just" 2000t (Falcon level, not exact number, with just 5-10t payload to obit) it will take 1000 years of milking that 1ha plot of land. Sure it takes less time to grow bigger, and 1x1km may spedup things to a decade or few(there is time required to collect energy to grow those limbs over that bigger area) All in all it decades between recharges, not a thing to do at wimp, unless it is some from of gray goo and it more tuned to this kinds of things, which can be if it designed. ## PPPS speeds and feeds of patch/"limbs"/energy collector growing * *"100x100m plot of land can bring about 2 tonnes of fuel" Hmm 🤔 perhaps we might consider a fungus, or something that shares some of its characteristics, this one covers 5.5 km subsurface with its Mycelium* – @Pelinore Growing a patch takes some time. If we take grass as our example, then it grows about 1g of dry material per meter per day, there is root system as well which also should be grown, let's say it almost the same size/mass as what is on the top. And full grown system is about 400g per m2 * grass is used in the answer, and elswehere in the post, only to estimate potencial of speed of growth or speed of producing useful chemicals("fuel"), just because I know some numbers about it, but by itself it not necessarly a best syste, however one of many possible solutions it may as well just look as an regular grass patch, but it does not mean it is your regular grass patch, or that it should look like one in other cases. But less stuff one has tk grow faster things go. ### speeds and feeds If we take our grass model as studu case then close to a best speeds case, speed of growth, how much it covers, doubles each year/season (not a strict calculation, but some approximation), then if it starts with 1m2 then it covers 1ha in 13-14 seasons, 1km2 - in 20 seasons, 100km2 - in 26 seasons. Exponencial growth rate, and artificial system can do that. Real grass patch probably grows more linearly, like proportional to circumference/perimiter of the patch - so it more like linear speed 1m per season, and 1ha is then in 50 seasons, 1km2 in 500 seasons. * real plants use seeds as well, to speedup, which are carried by wind or animals or.. So depends on strategy, and abilities of that organism its time to expand the means of collecting energy something in between those numbers. And depending on how much fuel it needs and speed of growth it will have some typical size as optimim between the speed of expansion to collect more energy and energy flow due time of that expansion. I mean that it all depends on events whjch have place in the system, for cases when we optimize it for time, there is an optimum between how much to invest in system which collects energy, and how much energy to extract after that. It typical EROEI, almost a definition of it, and specifics of what is actually optimal, is not an easy question, but at least it easy to say that be huge huge huge humongous big is not neccessarly a best strategy for all cases. But something up to around 1km2 may be a reasonable number. ### types of plants moss, grass, bushes, trees As for which plants to model after, all those 4 categories have their advantages and disadvantages in this situation, and it depends on climate and environment. Trees are good to extract stuf from depths, but they are expensive energy wise per square meters(poor EROEI). Moss is cheap energy wise to cover surface(good EROEI) but poor at extraction of water from depths so it grows in naturally moist environments. Grass and bushes are somewhat in between. Each of those potencially can create root system, but some horizontal tree like structures look like an solution in this case which nature and skme designs could take, as it needs channels of considerable sizes to collect stuff in a central location. Maybe more like lianes, on the ground. Just interconnected regular root structure won't do the job as it has other goals. (Tree roots have the goal to gather stuff to a central location - so it a good model) So as layout it may look like a mold from a top(or like a tree leaf), as strucutre elements it lianes(big diameter closer to collecting point, branching out like in a leaf), grass bushes as main energy collectin element. And its size pretty much unlimited, and only limited time how long it it sufficient for it to collect what it needs. But it just one of the potencial options, there is some variety of what kind of shapes it can potencially take to solve energy collecting problem. Parasitic properties to solve the problem, liane like, looks like a good strategy in the case, if there are forests to exploit, etc. That all is a deeper level of speculation. Consider things only on energy level, to a certain point is a lesser speculation, or if we skip which specific shape a solution takes then it is close to be not a speculation, because we rely on conservating of energy law, physics and such things. Specific solution it is a design work, and it can take multiple shapes, and is more subjective, to what people think is more viable or less viable. All in all - all kinds of specific solutiins can be reasinably imagined in this case, and which one is better realy depends on an environment, to which we have no knowledge about. [Answer] A planet might have a mountain (or a few) that extends far above its atmosphere. Or many; with atmosphere being something that exists in valleys. Creatures may have started climbing high to get away from air-breathing predators. And so evolved various forms that can go without air for a very long time, and also harvest energy from solar or other radiation. Eventually, such creatures reached the mountain tops. Wings are useless high above the atmosphere, but they may fly in a bottle-rocket fashion expelling gas and liquid. Useful to get away from an anaerobic predator, or for flying off a steep mountain to land far away. Extreme variants could expel 90% of their mass, to go as far and fast as possible. For this is an arms race, and the predators may have evolved the same trick. The best fliers survive. Now, if a small moon has a very eccentric orbit, perhaps it occationally get near enough that its gravity picks up such flying animals. At first, they simply used this to go further away and land on other continents. Eventually, they learned to stay in orbit, safe from predation for a while. Maybe they can take off from the small moon too; low gravity and it might have edible minerals like water ice. [Answer] **Your planet has a 1 hour day** You may have heard that most rocket launches happen close to the equator - that's because a lot of the work to get up to escape velocity is done by the Earth's rotation (about 1/24th). If Earth spun just under 24 times faster, anything "stationary" on the surface of the equator would be just below escape velocity. Your creatures can reach escape velocity by travelling to the equator and jumping. Of course, this raises its own problems. The atmosphere would also be at escape velocity, so would be stripped away (though fortunately your creatures have some capability to survive that - I wonder why that is?). But also, any perturbation of the surface of the planet would cause surface material to fly out into space and the planet would start losing mass - we probably can't actually get to escape velocity. To get the last little hurdle, your creatures follow a three step process: **Wait for an eccentric moon orbit** Your creatures have an innate understanding of orbital mechanics. So they can predict when one of those moons is about to come close to your planet - lending it's own gravity to assist any attempts to escape the planet's velocity (effectively reducing the escape velocity temporarily). **Get higher** You mentioned building dams, but there's another animal that builds structures - spiders. Only instead of making a web with a high tensile strength material, your creatures make a spire with a high transverse strength material - effectively making a small space elevator. **Flatulate** A by-product of making the spire-silk is gas. The creatures store this gas until they are at the peak of their spire, the moon is just overhead, and they let it all out. [Answer] **Riding the atmospheric electricity** The planet has exceptionally high levels of atmospheric electricity due to combination of strong magnetic field and strong star wind. (Or maybe there's a magnetar neutron star nearby.) So living organisms evolved to electrically charge seeds, then whole bodies, to spread themselves long distances. The higher, the better, and over billions of years this means adaptation to stratospheric vacuum and cosmic rays. On top of thunderstorms there are electric fields strong enough to accelerate dust to escape velocity. The creatures are much larger than dust though, but still very lightweight. Most of their bodies consist of very long carbon nanotubes and they resemble hair balls. The hair holds immense electric charge required for interplanetary launch by a storm. In space the hair is discharged, pulled closer and doubles as shielding against harsh environment. When landing on another moon/planet it is used as ablative heat shield and needs to be regrown. It all requires some way to manage electric charge of their whole body in vacuum, this means using ion beams or cathode rays. I don't think these are beyond the reach of biology. Or it is for them a primitive technology, like fire is for us. [Answer] # The Creature is lighter than air These creatures are born with a pollon-like airtight capsule structure within which they can withstand the extremes of space. When it is time to move on to another planet, they pump out as much air as possible from their capsule until there is a high vacuam inside their body. Terrestrial organs such as the pumping organ are discarded, and off it flies! 🚀 By the time it reaches atmospheric altitudes with air density matching its effective density, solar winds are strong enough to carry it. Besides periodic revival (for purposes as DNA replication to prevent irreversible mutations from accumulating), the organism ceases all chemical activity by radiating nearly all its heat away until it is just a few uK above 0. When it enters a hospitable planet, it revives for good, fills up with air, floats around until it reproduces, and then repeats the process. [Answer] The energy budgets of interplanetary travel on reasonably short time lines are insanely large. Earth's escape velocity is 11 km/s. Every kg of matter we push out of the Earth's gravity well is 60,000,000 J of energy. 1 kg of fat is 37,000,000 J; rocket fuel is in that same range, as that is basically what practical chemical energy can store. To convert stored energy to kinetic and not lose it all to atmospheric friction, you have to get out of the atmosphere rapidly, which means burning the initial stored energy fast, and probably starting high. Even if you lose a small amount to atmospheric friction, you'll still lose a bunch to entropy. This means for every kg of stuff you get out of escape velocity, you have to burn significantly more than 1 kg of stored chemical energy to do it. In turn, this means that whatever you eject out of the atmosphere is a small component of whatever sent it up. You can shave off a good bit of that kinetic energy by only reaching orbit instead of escape velocity. But that doesn't help as much as you might want if you want to reach another celestial body; the moon is about 400,000 km up, and reaching it requires almost as much energy as escaping the Earth's pull entirely. Getting there quickly also requires more energy than getting there slowly. ... Now, we could imaging bypassing the chemical energy problem. Imagine a planet with nuclear based metabolisms. Creatures have evolved to build reactors. The first creatures that did so "built" breeder reactors, which "polluted" the biosphere with waste products. This would first cause a massive extinction event, like the oxygen crisis on Earth did, but eventually creatures would adapt to this new energy source. After a time, the waste products would become food for other creatures. Biology would flow from uranium breeder reactor plants, whose waste products would feed herbavores, and then the herbavores would be consumed be carnivores in turn. Cold-reactor animals use the passive radioactivity of materials to provide energy over time. Hot-reactor animals cause cascades and have to actively moderate their nuclear metabolism. With the higher energy densities of a nuclear metabolism, making creatures capable of flying to space becomes more practical (if you consider animals who evolve nuclear reactors "practical"). The planet these creatures evolve on would have a higher metal content in its crust, and extremely exotic and toxic biology. But natural uranium has an energy density of 700,000,000,000 J/kg, many many times that of chemical storage. Orders of magnitude of energy forgive a multitude of sins. I am imagining a large blimp type creature with a reactor gut. It splits hydrogen and oxygen to inflate its bladder, and recombines it to descend. Heat pumps evolve to improve its reactor efficiency. Metals are used to build structures that biology doesn't deal with well, like high radiation, and are maintained by biological expendable "cells". Insulation in the form of foamy metal, and eventually vacuum chambers, develop to allow for higher heat gradients. This is exploited by heat pumps to eventually evolve cryonic storage, which improves the creatures ability to use oxygen and hydrogen. Rockets for high-altitude maneuvering, where the air is thin, start to develop; if you can go higher than your predators, you are safe. High-altitude is used by "pregnant" blimp-creatures to grow a child away from predators and food sources; the predators follow, possibly evolved over millions of years from the same blimp-creatures who fled the out performed predators. An arms race continues. Thrusting yourself into low orbit becomes a solution, no longer able to use the blimp for lift, but that doesn't matter as maintaining orbit becomes cheap. Ram jets, that pick up what atmosphere there is, concentrate it, heat it up by the reactor, and expel it out the back are used to reach orbit; rockets to stabilize. As food is nuclear fuel, these low orbit creatures are a food source. Predators evolve to eat them, pushing the orbital biosphere further out. [Answer] > > How could a creature reach escape velocity using only biological means? > > > Not practically. On earth escape velocity is 11.2 km/s, or over 25,000 mph. This is so far beyond anything that a biological entity can do I think I can confidently say it is not reasonable. This is also ignoring the atmosphere, which will make it much harder in more ways than one. You can reduce the size of the planet, for example Mars escape velocity is "only" 5.03 km/s, and mercury 4.3, but these are in the same order of magnitude and really do not help enough. The way it is theorised to happen is that meteorite impacts throw up matter from one planet that would achieve enough velocity to escape to another planet. [This could have happened to bring life from Mars to Earth](https://www.nationalgeographic.com/science/article/130905-mars-origin-of-life-earth-panspermia-astrobiology). [Answer] **Slow and steady...** Earth's gravity (aka, *acceleration*) is 9.807 m/s2. To make a point, if you have an acceleration away from the earth of 9.807000...0001 m/s2, you will eventually escape Earth's gravity. Said another way, if you have enough fuel to consistently travel, oh, let's say one mm/hr away from the Earth, you'll eventually escape it. Example: the ISS orbits 400km above the Earth. It'll take 45,662.1 years to do it... but if your fuel and supplies can hold out that long, you'd get there because your acceleration was in excess of gravity. But what if we run with your solar sail idea? Using [this uber-cool explanation of solar sails](http://ffden-2.phys.uaf.edu/webproj/212_spring_2015/Robert_Miller/physics.html) we discover that if we assume that the creature doesn't need food (e.g., let's assume a portion of the sunlight is used to keep the creature alive), then the creature could be the size of a bird and eventually leave orbit. *It will take a honking long time... but it would make it!* The problem is easily stated as, if you have enough fuel (sunlight) and time (food/energy), then you can always justify a creature biologically leaving the planet and traveling between them. ***Your problem isn't "can I travel in space biologically?" Your problem is, "does my creature design allow it enough food/energy to survive the time required for the trip?"*** Now, if we want the creature to be (\*ahem\*) *realistic,* then we need to worry about the fact that its sails won't be perfectly reflective, it needs food and water, etc. *But I like the idea better than flatulence that creates an initial velocity of [hundreds of thousands of km/hr](https://pwg.gsfc.nasa.gov/stargaze/SSHARP.htm)....* [Answer] Examining the ecosystem of the "creature" could help define the lifecycle and metabolic processes of the species. It must have a planetary phase, presumably where most of the metabolizing happens. A phase where it escapes the orbit of a planet. A phase where it crosses the vacuum of space. And a phase of reentry into atmospheres or landing on other orbital objects. These different environments are so extreme, in temperature variation, chemical composition, radiation levels, and gravitational forces, I imagine the creature would have to go through pretty dramatic changes during a very long life cycle. Different stages in the life cycle may resemble plant or fungal life more than terrestrial animal life. The planetary phase: Adult * Probably the most metabolically intensive phase. * Chemically, what does the organism need for its metabolic processes? * Probably survives best on smaller rocky bodies. Escaping the gravity well of larger gaseous planets poses more complications. * This may be the most active phase (or phases) of the organisms lifecycle, akin to a frenzy of mating and feeding and storing up the energy it needs for escaping orbit and the long cold journey through the vacuum. * This phase of intensive feeding may also be one of the core drivers in their ecosystem which pushed the evolution of travel between rocky bodies in space. The escape phase: Larval * After the creature has mated, reproduced and metabolized a colossal amount of energy it would enter the escape phase. * It could be imagined that individuals in this species have the ability to leave orbit on their own. Maybe they have some mechanism like the hypertrophied claw of a pistol shrimp that blasts them out of the gravity well into space. This would require a much larger, more complicated organism. * Another option is the mass ejection of offspring all at once at some point in the lifecycle of the organism. The organism may use naturally occurring volcanic activity to launch spores into space. Or like some plants use ballochory (ballistic seed dispersal) the organism may create eruptions of its own, producing volatile gases under pressure which result in a mass ejection of seeds or spores. The vacuum phase: Nymph * I like the image of the organism using large organic solar sails in the vacuum of space. This may be more animal, with sensory organs for detecting the infrared signature or gravitational field of small rocky bodies hundreds of thousands or millions of kilometers away. Or it may be more like a seed with a large sail on the solar wind. * Is the interplanetary or interstellar? The requirements placed on the organism change by significant orders of magnitude depending on what the volume of it's theoretical environment is. If the organism travels between rocky bodies within a single solar system this requires exponentially less energy than if the organism is also escaping the gravity well of the local star for interstellar travel. The scale of metabolism required changes dramatically. * It would take years or even decades to travel between planets within a system (a chemical rocket would make the trip from earth to mars in maybe 7 months but, the organism would have to survive longer, more unpredictable journeys). To travel between stars may take centuries or millennium. * To have a viable chance of seeding other rocky bodies within a solar system with offspring that can survive the diverse and extreme conditions would require millions of seeds or spores or offspring to survive the escape phase. Trillions of offspring would be needed to have a viable chance of covering the huge volume of even our own solar neighborhood in the local bubble. The reentry phase: Encysted or Cocoon * Once the nymph or seed became caught in another gravity well and began spiraling towards reentry, I imagine it would have to become encysted or form some sort of protective shell. * If it survived reentry into an atmosphere or striking some rocky body without any atmosphere then, I imagine the majority of cysts would still perish. The ecological window the organism can survive in would already be unimaginably wide but, can't be infinite. Even within our own solar system the diversity of the environments on rocky planets and moons is extreme. If the organism can survive and grow after splashing down into one of Titans lakes of liquid methane, I can't imagine it would have a very high survival rate in the dense atmosphere of Venus where it may be more than 400 degrees Celsius. [Answer] # Atmospheric mountains First of all, you don't need escape velocity. You need to be able to get to the Lagrange points between the planet and the moons. This already simplifies the matter a lot, but you still require insane amounts of energy to get there. ## "Getting into orbit" Getting into orbit is a tough job. As the creator of XKCD tells us: "The reason it's hard to get to orbit isn't that space is high up. It's hard to get to orbit because you have to go so fast." Getting into space then is 'easy'. Even an airplane has done it. The difficulty is staying there. Imagine you have a mountain or special balloon that goes to the edge of the thermosphere: [![Mountain to the edge of space](https://i.stack.imgur.com/KJZlw.png)](https://i.stack.imgur.com/KJZlw.png) Now if you throw something it'll just fall down to the Earth. [![Phone drop test](https://i.stack.imgur.com/yxBVm.png)](https://i.stack.imgur.com/yxBVm.png) What you need to do is throw it hard enough that the curve of throwing will go around the Earth: [![enter image description here](https://i.stack.imgur.com/V0kpi.png)](https://i.stack.imgur.com/V0kpi.png) On Earth this takes about 8km/s, or 28800km/h or 17895,5 mph. Even starting at the edge of space without wind resistance is a tough task. Even high speed meglev trains in near vacuum tunnels, so practically no friction, are thought to go 'only' 1000km/h. The hyperloops a a bit faster with an expected 1200km/h, but still well short of the mark. Even at a theoretical best of 8000km/h we're still way short. However, we don't need to get into orbit. We can do the simpler task of just getting off Earth and reaching the Lagrange point. If the moon(s) are in the right position, it's just straight up. If you reach the Lagrange point between the celestial bodies you have reached a form of equilibrium, allowing for your own solutions of navigating space. ## Getting to a Lagrange point Getting to a Lagrange point is just straight up, but not easier. The Lagrange point L1 between Earth and the moon is 1.5 million kilometers away. If you are at the edge of the Thermosphere you're only 800km away from the surface with about 8,8m/s gravitational pull instead of 9,8. That means you're still going to have to fight a rounded 1.5 million kilometers of slowly reducing gravitational pull to get to the L1 point. A big problem of rocketry is taking fuel with you. You have a payload. You make a rocket with fuel and find that you now have an extra rocket with fuel to take with you. So you extend the rocket and add more fuel. But you just added more rocket and fuel, so you need to add more... Luckily this does end with a fuel with high energy density. *If the density is high enough* you have more thrust power per weight of the fuel than the fuel itself weights. Yet here is one of the problems. A creature needs to feed on energy to survive. Next it needs to add absurd amounts extra to produce many times it's body weight (depending on the energy density of the fuel) as fuel. This needs to be stored safely for a certain duration of time and eventually into something that can direct and ignite the fuel. Iirc they often use a secondary fuel to supply oxygen for a good and powerful burn, meaning you need two kinds of containers. Suffice to say that eventually you need a lot of energy and materials to get to L1 even from the edge of space. It doesn't matter if you use magnets, fuel or telekinesis. The power to get a positive speed away from Earth all the way to L1 needs to come from somewhere and is a lot. The only option to achieve enough energy in any plausible way is that it's a tiny, tiny creature. That means that if the conditions are right it can gain a lot of energy from the environment, like bacteria in hay have an abundance of energy around them that they can start spontaneous fires. A large size creature like a human simply can't do this by any plausible means and survive. Though I have to say it isn't impossible for biology to create high density fuels inside them, it seems a bit out of reach as well. # How to make it as plausible as possible? To make it as plausible as possible we can do a few things. The climb out of the atmosphere is the hardest part, as you need to also content with the air friction. Having a less thick atmosphere will help a great deal, both in depth and density. If it is thin enough you can have a mountain reach part or even all of the way. That way the climb can be done in steps instead of all at once. Spreading this effort for going high into the atmosphere will already help a great deal. Alternatively you can have the creature use something like a weather balloon. They can reach up to 120km in Earth atmosphere. The problem of balloons however is that they can't really go out of the atmosphere. At best they can skim the edge, like a ship on water, but this would be extremely difficult. A thinner atmosphere would also be a reason for the creature to exist. It is closer to space, with a more abundant or stable food source if it goes outside the planet's atmosphere. A less dense planet with a lot less gravity will obviously also work. To gather enough energy it would need to be small to take advantage of unexpected high densities of energy that can be gathered and processed if needed. A problem is that it would need to move the energy relatively further than a bigger creature if you want to climb a mountain for example. Maybe it would be better to not travel the system and stay closer to Earth. Go up that mountain jutting just out the thin atmosphere and bask in the rays of the sun. Or have it be a weather balloon creature that skims through the high, thin layers of air. With little protection of the outside layers they should be bombarded by the interstellar radiation. Each is more plausible than making high grade rocket fuel and launching into space. But last and not least, you could have these creatures be in an asteroid field. They could feed on the debris and use ice for oxygen, among other things. As the gravity of the asteroids is already minimal and no atmosphere to speak of they can easily escape it, extending their tendons to sail through the massive asteroid belt and collect interstellar radiation. ]
[Question] [ Is it possible that, through any plausible history of alien life, and any plausible method of propogation for a self-replicating spacecraft, that the universe, as seen from present day Earth, could be inhabited by self-replicating spacecraft that have gone feral and settled into distinct niches like planetary life? [Answer] You have a number of key words in your title: > > ecosystem of feral self-replicating spacecraft > > > In order of formation: **Spacecraft** can be built by an Earth-like civilisation. Let's assume that they came from Earth, where we know life exists [citation needed], about 66 million years ago - built by the dinosaurs slightly before they had an [extinction event](https://en.wikipedia.org/wiki/Dinosaur). (Probably for unrelated reasons, but we'll get to that.) **Self-replicating** spacecraft are trickier, but are theoretically within reach. Given 5000 years more, the 'simple matter of programming' may be solved even by humans. Since we're starting a few million years ago, even 5 millennia is insignificant. **Feral** spacecraft are trickier, but much more likely if they're self-replicating. How they've escaped control is the preserve of your story, but we could assume that someone uploaded an AI to one and it had different priorities to its creators. It's relatively straightforward for it to arrange an ['accident'](https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event) for them if it's patient. **An ecosystem** is unlikely to evolve from this system in plausible time. DNA is a fairly stable storage mechanism, but an AI can actively error-check itself and build more redundancy over time. So no, an ecosystem (competing, different forms of life) is far less likely than a mega-system of interacting robots working on the AI's chosen project(s). However, if the AI has different instances which disagree, you might rapidly see this. --- Spread: Assuming that there's some kind of intelligence, it's entirely plausible that almost every star nearby will have some kind of AI installation interacting it. This galaxy is about 100K ly in diameter. So the AI can easily traverse and colonise it if it can manage 'only' 5000 km/s (1/60 *c*) in interstellar space. It'll take 6M years to cross, but between smiting its creators and now, it has ten times that long - plenty of opportunity to see the sights, share pictures with friend-clones, and grow bored. At which point it may toy with self-competition and become a form of life, or take up gardening and make some. Reaching Andromeda (if it had started soonish) would require about 3% *c* on average to arrive by the present day. --- Edit, integrating comments on other paths of evolution: If the AI instancaes *diverge* but with a common goal, then small areas will become test-beds for other designs, giving a rapidly-evolving version of this effect on a local scale. If the machines are all sub-AI and have been left uncontrolled because someone made an error in calculating the impact velocity of a direct-delivery asteroid impact, then adaptation can proceed unencumbered by checksums, and may be driven by an optimisation-gone-unchecked. If the AI is self-upgrading, then "evolution" is a moot point - the principles of intelligent design will apply, though that can include some random experimentation to generate ideas or tune settings. This will mean that the AI may not seek to fill all niches, but may instead dedicate its resources to the most useful- or interesting-looking ones. Notably, some of these paths result in Earth being left alone, which may be useful to your story. [Answer] # Definitely First, let's define "the universe, as seen from present day Earth." [This question](https://physics.stackexchange.com/questions/45759/what-is-the-farthest-away-star-visible-to-the-naked-eye) suggests that [Eta Carinae](https://en.wikipedia.org/wiki/Eta_Carinae) is the farthest star system visible to the naked eye from Earth. It's located 7,500 light years away. Let's imagine an alien species that's capable of flight at half lightspeed. To be able to cover everything within 7,500 lightyears of Earth, they could multiply new VonNeumann spacecraft and get to every star system in tens of thousands of years and populate the observable (to the naked eye) universe. I'm being vague because, in terms of the age of the universe, that's the blink of an eye. So the question is if they can develop the technology between the creation of their species and circa 50,000 BC. If you have a species that's, let's say, a billion years old, they could have created the necessary technology with time to spare. [Answer] ## Absolutely. I've [asked a question](https://worldbuilding.stackexchange.com/questions/195621/when-is-the-earliest-that-the-universe-could-support-planets-with-long-lasting-b) about what's the oldest civilization of precursors can appear, got the answer of several billion years. Conservative estimates for coverage of our galaxy with von-Neumann probes ballpark somewhere around half a million to million years, so this leaves plenty of time for evolution to take place in the feral probes to develop ecological niches and whatnot. If we just stick to STL means of propulsion, this means hundreds to thousand years between voyages - and between reproduction cycles presumably, so evolution might be glacial compared to planetary biospheres, but this can be freely adjusted as needed for the plot via the fact that artificial life might evolve quite significantly faster than traditional DNA-based evolution, and you can basically choose any speed that fits your story. [Answer] Yes. The earth spent 1 billion years doing basic nothing, but photosynthesis so it could bond to iron in the water. A planet only 10% smaller would have 100 million year jump on us. The planet could have had extra oxygen, or oxygen rich asteroids, meteors, and etc could have impacted planet dramatically accelerating the process. Either that or other materials that when combined could form oxygen could have speed up the process. Most of human advancements have happened in last 2000 years or so, so any race with even 100,000 year head start could totally do it. Even 10,000 years would be a huge advantage. We basically have the technology today to have self replicating ship already. 3D printers exists, and if you have enough money you can even have one that does metals. 3d printers that do plastic are already abundant and you can have one for a couple hundred dollars plus operating expenses. So as long as the ship can ingest rocks, separate, and refine those rocks into their base components 3d printers can print virtually any replacement parts. Obviously you will have to have a factory area to turn raw materials into whatever the 3d printers need. They will have to have some kind of fabrication plant for chips like CPUs, but it shouldn't be a problem. As long as each ship maintains an inventory of spare parts this should be a non-issue. Technically, if someone had the billions of dollars to spend we could have one today. As long as the AI keeps learning and improving itself each new generation of ship should be significantly better than the last. Eventually it should reach Star Trek levels of advancement. [Answer] # No reason not to There is literally nothing stopping you from doing so. ## Spaceships Literally anything that’s vacuum-tight, ranging from Mercury rockets to Saturn V to the Millenium Falcon. ## Self-replicating There are factories that build cars, that are run by robots. As long as there was some sort of material gathering facility also run by robots, your set to have your Eternity Fleet ## Feral The definition of feral is as follows (google search): (especially of an animal) in a wild state, especially after escape from captivity or domestication. So I guess the robots just existing counts as feral (?). ## Life Hard to say. As you said, the ships are feral and the definition of being feral is being wild after leaving domestication, then your native species have (probably) died off. Either that, or they had some evolutionary devolving. You could easily add a group of space hermits of a different species though. ]
[Question] [ In this scenario there are two spacefaring empires, each with a handful of solar systems under their control. The two empires have been adversaries for millennia. In each solar system there are habitable worlds. Any indigenous population on these worlds was forcibly conscripted into the empire that found them first and operate as a vassal state. Unoccupied worlds were populated. The technology in this scenario allows for planet-to-planet travel in a matter of hours. Imagine 1 hour from Earth to Mars, or 10 hours from Earth to Uranus for scale, something akin to air travel for us now. System to system travel, while faster than light, still takes centuries. Neighboring systems might be 200 years, while the frontier systems may take 800 years or more to reach from the core worlds. Most of the beings in this universe have a life span similar to humans - assuming technological advancement in health care and gene-therapy, maybe 200 years. Cryogenic suspension is possible but difficult. The question is: What does this war look like? Sending a fleet to assault a system would take hundreds of years and several generations, and would be seen coming decades before they arrive. Also, those ships would be unavailable to counter some other offensive launched against their civilization. I have a few options on the table already: * Attaching drives to meteors or other large space rocks and launching towards the expected location of the system. These could travel faster than the ships, maybe decades instead of centuries. I assume these species could to the math for where to aim them. * Ships full of robots, again these could go faster than 'squishy' ships. They would be hard pressed to accommodate changing commands though. * Ships with no crew but full of bio-weapons. Note: For the sake of the story, let's assume communication is near-instant across systems. Thanks! **Update:** Just to provide some clarification, each side of this war has a deep-seated, almost religious belief that their empire must be the one to control the stars. There's nothing political about the war, it simply must happen, and must continue until one side wins. Second, neither side wants to rule over a galaxy of glass balls in space. They know that habitable planets and populations are valuable. Each side wants to conquer the systems while still having something to rule. Since all but the original system for each empire was forcibly conquered in the first place, a change of allegiance is realistic. (Perhaps several systems have been passed back and forth already) They would be willing to 'nuke' a planet or two if necessary, but for the most part the goal is to take control of the planets under the other empire's control. The 'vassal state' planets are effectively doing their own thing in terms of society, but they are directed by the overlords to help the war effort - for example 'attack planet x' or 'build shipyards'. **Update 2** First of all, thanks everyone for the feedback and ideas. It's a lot to wade through and there a lot of ways this could impact the universe I'm thinking of, I'm going to need to unpack it all in my brain. Second, I need to apologize because I muddied the question by referencing FTL. My intention was to ask what a war would look like without planet to planet travel times being short, like in Star Trek or Star Wars. Going back to my old math / notes, the speed I'm looking at for ships is about 10% of Light speed, or around 1,000,000km/h. At this speed, Earth to Mars would be less than an hour, Earth to Uranus about 25 hours, and Earth to Alpha Centauri would be 42 years, Earth to Wolf1061 would be 140 years, etc... Not accounting for acceleration issues, if there are any with this level of technology. I want it to be somewhat science-based but a little handwavium is OK to keep the story entertaining (it will use real star systems and their real distances for example, but somehow maybe the aliens all have a universal translator). Third I think technology of the two main factions would basically have plateaued. The vassal planets might not all have an even level of technology, but overall there aren't any game changing discoveries that change the balance of power on a regular basis any more. [Answer] ### Your war needs an exceptionally strong reason to fight The war needs to have some fundamental underlying driver beyond almost any existing war in human history. No resource shortage, no class divide, no empire expansion desire, no desire to self govern, no desire to liberate captured land, nor any other war justification in history, is going to survive 8 generations of travel. I will fight to free myself or my children from suffering. I may fight to avenge my parents. Grandparents if exceptionally motivated. 8 generations back? I just can't get motivated enough to give (yes - give, I'm not going home even when we win) for the [Bolivian War of Independence](https://en.wikipedia.org/wiki/Bolivian_War_of_Independence) or the [Battle of El Toro](https://en.wikipedia.org/wiki/Battle_of_El_Toro), nor any other conflict that affected people 8 generations back. I don't believe propaganda could stretch this motivation out for 200 years; brainwashing from birth might work for a few, but you want your military to be able to think on the move - and that teaching them to think can break centuries old propaganda. Thoughts on what causes that may survive 8 generations: * Religious indoctrination / crusade. You brainwash the children on the generation ship to wipe out evil non believers. * Some pure indisputable evil force. Literally Satan sort of thing. * Some out of control tech which can't be negotiated with (eg an out of control AI that wiped out its people). * Some enemy who will attack you for a fundamental need. Eg Wraith from Stargate, or some other smart monster. The standard "We better attack now because they're about to attack us" line used to start most wars of aggression wont stand up to 8 generations of scrutiny; it's only been a few decades since these lines: * ["Oh no these Polish troops invaded our sovereign German radio station! We must respond!"](https://en.wikipedia.org/wiki/Gleiwitz_incident) * ["Iraq has stockpiled biological and chemical weapons, and is rebuilding the facilities used to make more of those weapons."](https://www.vox.com/2016/7/9/12123022/george-w-bush-lies-iraq-war) ... and already we can dismiss these as fiction / propaganda. Few people today believe Poland attack Germany first, or that Iraq had a serious large stockpile of WMDs. ### What would the battle look like? Your generation ships are going to be the centerpeice of your fleet (they're big, important, but vulnerable). Escorting these will be smaller, faster, remote-controlled fighting ships which do the bulk of the work. Basically a carrier battle group. Carrier in the centre, smaller ships around it with specialised weapons-platforms for each potential threat (Air / sea, submarine). You'd have a similar variation: * Drone ship - that drops small fighting drones. * Big gun-boat style ships for close in annihilation or wiping out incoming projectiles in a hail of flak. * Missile frigates for precision distance attacks. * Carrier which can launch lots of robotic small fighting craft. * Artillery Ship with a big central gun for when massive firepower is required. * etc. I'd have an automated defence drones that hides itself with close-to-ambient-as-possible temperature and passively scanning for threats, and powers up and shoots anything that doesn't pass an IFF challenge. Deploy these liberally around your systems for defence. Then launch your fleets. As your fleet travels, they should distribute these defence drones into no-mans-land between your systems, over as wide an area as possible. Basically trying to mine the good transfer orbits between the star systems. These will need to be redone every few decades, (or the drone mines need to power up and move every year or so) as their orbits will drift. While in transit, your middle generations have nothing to do other than raise their children, so have them upgrade the robotic fighting ships as new tech is discovered. Your only a few light years from your home base you can get data bursts of new tech. A modular design for ships, a dry dock in the generation ship, and onboard 3d printers should help keep the robotic fighting ships mostly up to date in transit. (No they wont be as good as freshly made ships, but it's better than nothing). As you approach an enemy system; Decelerate your generation ships before the bulk of your fleet. The remote controlled ships go in and do the battle, the generation ships stay back, using remote control to keep themselves as far away from the fighting as possible, but close enough that they can direct the battle without serious transit time issues. Once the defences are destroyed, then bring your generation ship in to land and use as an occupying force. [Answer] Since you seems to want two fairly evenly-matched sides, there are three broad possibilities for what a conflict will look like: 1. A Korea-style defensive stalemate. The cost of attacking prepared defenses is so much greater than the cost of building and maintaining those defenses that a successful attack is essentially unaffordable. Wait for the other side to collapse due to some other cause. 2. A Cold War-style offensive stalemate. Mutually-assured destruction using unstoppable planet-cracking FTL warheads. Wait for the other side to collapse due to some other cause. 3. A World War I-style vast war of attrition that will drain (and eventually overthrow) both sides. The 'overthrow' result is not trivial, so any smart Royals in your empires might steer toward one of the other stalemate options in order to keep their head. [Answer] The only option I see with an actual chance of winning would be a "colony-hopping"-approach. The reason for this is very simple: A travel time of 200 years means that the attacking side simply has no chance. Not only because they will always be 200 years behind in technology, but because of the supply line situation combined with the generally stronger position of the defender, who has all the time in the world to prepare. Therefore the only rational approach would be to gradually establish colonies/outposts into the direction of the enemy, thereby constantly closing the distance with the goal of establishing an "assault-colony" near the enemy empire, that is capable of building up all the necessary infrastructure, manpower and ships to launch the real invasion. This would be obviously be a an endeavour of enormous proportions, taking place probably over millenia and requiring a zealous intergenerational devotion to it, which is given by your parameters. What makes this approach especially interesting is the very likely prospect of both empires doing it simultanously, which would lead to a massive clash somewhere in the middle between assault-colonies that only exist to invade the enemy. [Answer] ## Special relativity forces FTL travel to be instantaneous... ... at least from the frame of reference of the people travelling. Yes, I'm aware that *faster than* lightspeed travel isn't accounted for by special relativity, but you're asking for a science-based answer on top of the existence of FTL travel. Travelling at *exactly* lightspeed would effectively render time to stand still (for the traveller). It stands to reason that going even faster, if that is assumed to be possible, is not going to "undilate" time. However, you can still have this journey take centuries from the frame of reference of the people inside the solar systems. But this does change the basis of your question. It becomes a sociological issue, rather than a technical one. Using a real world example, where you can assume lightspeed to be the maximum achievable speed, the Sun and Earth are 8 minutes apart when moving at the fastest possible speed. Assuming we had the means to immediately travel at lightspeed, let's say something is happening on the surface of the Sun that requires our immediate attention. For the sake of example, let's say the Sun is going to burn out unless we plant this magic rock on its surface. If we wish to intercept the sun burning out, then we **MUST** leave on that mission at least 8 minutes before the sun will actually burn out. That's simply because we must account for travel time. If we start travelling with only 2 minutes left on the deadline, then there's no point to even going on the mission. Going back to your example, if your travel takes 200 years, that means that you must leave on your mission at least 200 years before it's too late to do so. You clearly have *some* maximum travel speed in mind. It's faster than light, but there's still a maximum. Based on that maximum, there will be a certain travel time, which in turn will be relevant for every decision on whether to send people on a given mission or not. --- ## Technological advancements over the centuries So, we're sending our finest troops into combat. It will take them 200 years to get there, but it will feel like a fraction of a second to them. Essentially, we are sending [troops with weapons dating from 40 years *before the US civil war*](https://i.pinimg.com/originals/01/97/f5/0197f593cdd68d2ca733b314f49da0d5.jpg) to fight [modern day Navy SEALs](https://cdn.britannica.com/45/152345-050-A4823C01/beach-US-Navy-SEALs-training-exercise.jpg). I actually cheated in your favor, the first picture is from during the Civil War, 40 years more recently than the actual guys you'd be sending. It's not hard to see how they are going to be at a tremendous disadvantage. Realistically, for a 200 year travel window, you would need to be 200 years *ahead* of your opponent in order for your troops to arrive with a fair chance of winning an engagement. But it gets even worse. You have stated that there is near-instantaneous communication between these systems. That means that the people in the target solar system can be warned 200 years ahead of the arrival of the troops. Not only can you forget about shock and awe tactics altogether, your enemy has several generations to prepare for your arrival. Worse still, your technological advantage can be undone if your technological advancements can be transmitted to the enemy forces - who will be able to develop that technology much faster now they have your plans. We're sending civil war troops to engage Navy SEALs, and the SEALs know you're coming. And they've had literal generations to prepare for your arrival. Good luck with that. --- ## Zealotry as the "solution" > > Just to provide some clarification, each side of this war has a deep-seeded, almost religious belief that their empire must be the one to control the stars. There's nothing political about the war, it simply must happen, and must continue until one side wins. > > > However, you seem to be describing a situation that is going to be rife with zealotry. That works in your favor. Rather than finding logical and scientific reasons for why this engagement is going to be an uphill battle to say the least, zealots following dogmatic ideals tend to gloss over those kinds of considerations. I would expect that the only people who'd still engage in this ware are zealots who are convinced that: * This war will never end, the enemy will remain our enemy in perpetuity. * "We" are invariably superior to our inferior enemies * "God" will *make* us victorious above all else * All of the above will trump any possible technological advancement the enemy may have. Essentially, you need militaristic egocentrical space zealots. It's very possible to create this kind of civilization. Whether the citizens themselves are such zealots, or they simply churn out a clone/cyborg army to do the work for them (with the actual citizens knowing "better"), it can be done. But this kind of civilization, and the sociological issues that readers are going to pick up on (essentially space nazis) are going to very much attract the spotlight of the story. It's going to be hard to write a story with a satisfying arc where these problems do not get addressed. Again, not saying it can't be done, I'm just warning you about how much of a magnet for plot attention this civilization is going to be. It actually reminds me a lot of the Warhammer 40K kinds of civilizations. These are built with strong tones of militaristic religion ("inquisitor", "heretic", ...), and built on an age-long conflict between races that do not inherently change at their very core. The technology may change, but the attitudes towards each other do not. [Answer] **There's no science-based reason they would have to be seen** If your ships are traveling FTL, then there's very little chance of them being spotted unless you, the author, invent a reason. They're out-racing their own light, so the ships would arrive before the enemy star system would see the light of their initial launch. As long as you have fairly good sensors and put a minimum size on FTL vessels/transmission equipment their arrival will be a surprise. (such that, for example, your civilizations can track anything bigger than a car within their systems and FTL ships must be at least Aircraft Carrier size, or that FTL comms are big and obvious so a guy in a house can't just call the target planet on his cell phone when the fleet leaves.) Even if they need to exit FTL at the system edge and use their super-fast "normal" drives for the final approach that's only a couple day's warning, which isn't insurmountable. As to the potential centuries of tech improvement by the waiting enemy, that's also somewhat overcome by history. The pace of technological advances in the past few centuries is unheard of in human history. It's been increasing, but historically relatively small incremental change over centuries or even millennia has been the norm. All if would take is a throwaway line (or a basic assumption left unsaid) that the "technological singularity" everyone is currently talking about was actually a dead-end. No "Oneness with the machine", turns out that after FTL and quantum computers damn near everything else is impossible! Then it becomes the difference between the Brown Bess (workhorse musket of England designed 1772 and used until 1836) and the model 1858 Springfield (common in the American Civil War and technically a superior weapon by 85 years). The fighting happens the EXACT SAME WAY with both weapons. Then the arm's race becomes novel ways of using old devices or desperate gambits where fleets are launched with some Great New Wonderweapon with the knowledge that it took 2 centuries to produce and previous wonderweapons have taken 2 centuries to overcome. So if your travel time is 180 years you might just overwhelm the enemy! Not a system a ration civilization would use to launch millions into the void, but religious zealots? They're rushing to the recruiting stations! If both these things are true then you'll end up with two VERY belligerent, evenly matched galactic superpowers duking it out in the Grand Old Space Oprea Style! I can imagine that the troops actually involved in the fighting think of themselves as an elite race apart (fitting, for the religious zeal your civilizations have). Travel for them feels instantaneous, so they go from battle to battle aloof from the material universe (and largely not knowing about it, as they lose centuries at a time!) making war as their High Priests will in the name of their God. [Answer] **Cyber Warfare** If travel takes centuries but communication is instantaneous, there would be a very strong incentive for informational warfare. Your empires would try to convince locals on the enemy planets to fight for them, launch virtual attacks, broadcast plans for building nukes in your garage, spread disruptive rumours... **Defense is easy** To actually capture the thus weakened planets, you'd need a massive invasion force. Defense would probably be easier than offense, especially if you want to take the enemy planets intact. Any attacker would be seen for many decades before arriving, which allows the defender to prepare an appropriate reception - possibly including asteroids slung in the way of the attacker, which would impact at more than 10% of light speed due just because of the travel velocity of the attacking fleet! **Tech Rush/Eco Rush** One way to counter this advantage would be an even greater economical or technological advantage. You would want to play the long game and try to improve your capabilities at a faster pace than your enemy, until you felt confident in your ability to overwhelm any defensive system they could deploy in the 100 years of travel time. **Mind Games** You could improve your economical advantage by making the enemy waste resources countering "attacks": if you launch asteroids painted like death stars at them and tell everyone how powerful they are, they might spend a considerable amount of resources trying to intercept them, giving you the opportunity to save up for an actual attack. Bonus points if once in a while you mix in an actual generational attack craft full of smaller combat vessels, which would try pierce the front lines and damage or destroy major economical installations (shipyards, factories and energy producers, but also population centers). They could also play dead or hide inside an asteroid ring, to ambush transport ships passing by. **Asymmetrical Warfare** If you are able to penetrate the defensive line even with minor assets, guerilla warfare becomes hugely attractive. Orbital mechanics make pursuit much more expensive than evasion, and there are bound to be soft, valuable targets even a lightly armed vessel could destroy. Having to defend every factory complex and shipyard against possible sneak attacks also places a huge strain on their resources. If you dislike asymmetric warfare, there is another option. The closer you are to your enemy, the less time he has to prepare for attacks, and the better you can judge the state of his defenses. Therefore, reduce this effective distance: **War Factory** You build a gigantic habitat and production center, continually supplied by asteroids shot after you from your home system. It processes these into weapon systems, ships and potentially even more interstellar factories. Because of its size, it gives a defensive and logistical advantage close to that of a moon base (perhaps it even is a hollowed out moon) and travels slowly enough to easily evade or deflect incoming asteroids. Since it is upgrading and extending itself all the time, traveling at only 0.02 c is actually not a problem: it only allows you to receive more resources and build more offensive and defensive assets. Once you are in range, you can fight a war without all the logistical nightmares of combat vessels 200 years away from their base, and as long as you resupply your station with raw asteroids (which are *relatively* easy to launch with gigantic magnetic cannons or accelerated on laser sails) you can continually resupply, rebuild and otherwise support your military assets. **Stealth** During the interstellar flight of your factory, you could also launch sneak attacks: Ships launching from the station would not be seen by either your enemies or spies on your homeworld, and preventing communication from a military base in the middle of space would be comparatively easy. You would launch small, hard-to-detect craft and send them off into the cluster of your enemy (not directly at one of their stars), and then either pose as a trader coming from one of *their* planets or as some rouge rock coming from the opposite direction to where the enemy is looking. If only a few get through, do guerilla stuff; and if you can embed houndreds before the enemy notices, you can draw away their defence force with a feint attack and let the "comet ships" unleash hell on their infrastructure... **Final Option In Case Of Stalemate** You tried for thousands of years, but couldn't get through your enemies defenses? Weaponize one of your solar systems. You start building a dyson swarm and equipping each module with a big laser and accelerate your star using a Shkadov thruster (or a Caplan thruster if you are in a hurry). After 10 million years (Shkadov thruster, 3 ly distance) or 500000 years (Caplan thruster, 8 ly distance) you would reach your enemies planet and, now having built the whole dyson swarm weapons array, could easily dispatch of their forces - assuming they don't have a weaponized dyson swarm of their own. You could also use such a laser array to fire a death ray over distances of many light years, but since movable assets could still dodge - light speed is finite, after all - and you want to take the planets intact, that might be inferior to moving closer and killing the enemy in "melee combat" (<1 ly distance). [Answer] I do not believe victory is possible here. You are describing a technology that permits relativistic kinetic energy weapons. Since the objective is conquest rather than obliteration these would not actually be used, but they would exist as a last resort to ensure you didn't lose. Both sides would have them, therefore neither side could lose, thus you would not have open warfare. The closest model we have is the Cold War. ICBMs take the role of RKEWs. You would also see both sides trying to build new colonies unknown to the other to provide survival if the RKEWs ever did fly. [Answer] ## It will be a massive conflagration of counter-strikes. The basic problem in your universe is that it takes troops (and in general *everything*) a couple hundred years to travel between star systems. Now, as @Flater already pointed out, if your ships go FTL then your crews will experience practically no travel time (or even arrive in the past, but you probably don't want to open that particular can of worms). However, the people they are attacking will have had up to twice the fleet's travel time[1] to resolve their differences. As a result, the invading fleet will have exponentially higher morale than the people they are attacking. The high moral of the attacking fleet, combined with the inherent problems of defense in space[2], will mean that the attacking fleet will initially be able to do a *lot* of damage to the world they are attacking. They will probably be destroyed immediately afterwards[3] due to the defenders' technological advantages, but the damage will still have been done. However, it doesn't really matter how much damage the attacking fleet does. **The defenders will have a serious case of Spanish Honor / "Righteous" Indignation, spurring them to launch a counter-strike.** When this counter-strike reaches the enemy planet it too will in most likelihood be destroyed, continuing the bloody cycle. **Even if the attackers use planet-killing weapons, it won't make a huge difference**; the planet will have time to see its impending doom and spitefully send off a huge fleet. --- [1]: The travel time of the fleet itself + the travel time of the fleet due to which it is counter-striking. [2]: The problem with defense in space which nobody mentions is that space is big. *Really* big. Furthermore, it's big in all directions; attacking fleets don't have to come in on the plane of the ecliptic, and can split into multiple groups to ensure that at least *some* of them get through. As a result, defense in depth is more or less impossible. [3]: Even if they do, by some miracle, manage to win, it'll be just that: a miracle. Attacking fleets do win occasionally, but not enough to stop the cycle. [Answer] At 200 years FTL travel time, that is *not* a neighboring system. But it may well be a neighboring inhabitable system. At 200 years travel time, we also probably aren't talking more than one ship every 10 years, and probably more like every 50. So every 25 years a ship arrives, takes out the incumbent government, sets up a government on the other side, and adds some colonists. Within 25 years, the new ship either isn't well functional or departs, just in time for the other side's ship to arrive. After this happens a while, the two sets of colonists make peace and decide they don't want either empire, establish a joint government, and deceive various incoming ships. Personally, I see this as comparable to England, France and Spain fighting over the new world. [Answer] I would imagine that they don't even try to send ships to attack each other. if communication is near instantaneous, they will each invest heavily in cyber attacks - if you can take over even a fraction of their technology in one of the outer worlds of their solar system, you could use that to build a devastating weapon and they would have much less warning of anything happening. Each side would have amazing cyber security but everyone would also learn to be hackers. The only time they would actually travel between systems would be if they a) already overtook a system remotely and want to inhabit it or b) to send small ships that would get past the enemy radar that future generations could activate to inspect/take over the enemy equipment via rewiring/reprogramming it directly or to build their own weapons on the fringes of the solar system. [Answer] Under the circumstances, I suggest combat by stiffly-worded letters to the Editor, conveyed at lightspeed to the offices of the Intergalactic Times. I believe there are precedents for letter writers having conducted warfare in this matter for the best part of a human lifetime. [Answer] In addition to some of the other nice answers here: **Propaganda** We (the humans) have been conquered 1,000 years ago by the Aardvark people. They leave us to run our own planet but demand that we provide resources, production and manpower to their empire. Now, look at that fancy instant communications technology\*, that means that all-day every day we are getting junk email, robot telephone calls and other messages from the Ostrich empire saying "Hey guys. Are those Aardvarks oppressing you? If you fight for independence then we can protect you from being re-conquered by them? By the way here are some weapon schematics the Aardvarks would prefer you didn't have." Then, 1,000 years later the messages read: "Hey Earthlings. We hear the Ostrich people are treating you real bad. Looks like all the weapons they taught you to build just deactivated when they wanted them too huh? We can send data for some new types of weapon. Fight for your freedom!" Over hundreds of captured civilisations, and some period of time, the better propagandist wins. I am imagining an entire species of super-cute puppy-like aliens appearing on the broadcasts every day telling you how the Aardvarks are committing a genocide to wipe them all out. Of course the cute aliens and the genocide are fictional, cooked up by the Ostriches. But the fake videos are super convincing and it would take 1,000 years to fly to the star system it is supposedly happening in and back to check for yourself. Maybe a "clean up" fleet needs to be sent to finish off the last star system or two that just likes the Aardvarks too much. But by that point its hundreds of systems vs. 2 s \* We will assume that normal science fiction rules apply and FTL works but for some reason does not provide time travel. ]
[Question] [ I want to create a planet with a deep gravity well, say about 12G at the surface. At first I wanted the planet to have either no atmosphere or a very thin one. But I want this to be as close to realistic as possible. So, would a planet be guaranteed to have a thick atmosphere with a gravity well that deep? [Answer] You ask a tricky question because the case you describe -- a rocky planet with 12G surface gravity -- is extremely unlikely. If the planet is defined as being rocky, then it's made of normal matter (not neutron star or white dwarf stuff) and to have 12G surface gravity, it would have to be quite large. For a constant density sphere, the surface gravity increases proportional to the sphere's radius, so to have 12G surface gravity it would have to be around 12 times the diameter of the Earth. (The surface gravity is proportional to the planet's mass which is proportional to the cube of the radius. And surface gravity is also inversely proportional to the square of the radius (because the surface in further from the center and the inverse square law). The net effect is a proportionality to radius.) Even rocks compress, so 12x is somewhat of an overestimate. Say it's "only" 10x the diameter of the Earth. It's still very difficult to see how a rocky planet 10x the diameter of Earth (meaning a mass of 1000 Earths -- greater than Jupiter!) could avoid picking up a huge atmosphere of gasses and being a typical Super Jupiter or even a small star. About the only way I can think of is if the star it circles went through a very high luminosity phase and stripped away nearly all the atmosphere. (Since hot Jupiters are common, it seems unlikely that a planet that massive even one forming near a star could avoid a big atmosphere. It pretty much has to have had its atmosphere stripped later.) Not so clear that life would survive on it then. [Answer] Likely, but not guaranteed. Consider a large rocky planet very close to its star. There is certainly a possibility that the atmosphere would be boiled off / stripped away by the star. This would be the case if, for instance, Mercury were orders of magnitude more massive. If your large rocky planet is close enough to its star to make this case true, you will have to deal with strange conditions for your character. One example is the planet is likely to be tidally locked, with an extremely hot side always facing the star and an extremely cold side always facing away from the star. Whether humans have actually discovered a planet that meets these criteria is probably up for debate. Most inquiries into exoplanet atmospheres make the assumption that the existence or lack of atmosphere is unknown until the presence of an atmosphere is proven definitively. [Answer] I think I see a scenario that could produce your world. Note that this is cataclysmic on an interstellar scale--life on nearby stars would have been eradicated. We need a system that starts out with three stars, two of which are a close binary and each star exceeds (but not by too much) 8 solar masses. The third star is more distant and somewhat smaller. The two big stars burn through their fuel and supernova, leaving behind neutron stars. The third is abused by these detonations but survives. The neutron stars are like their parents--a close binary. In time they spiral in and go splat--but enough mass is thrown off in the process to make your high-G world, from which a planet is born. (Note that I'm not sure it's possible for it to end up in a planet. The process is **extremely** energetic, it might be ejected too fast.) Now you have a neutron star or black hole, a super-planet and an ordinary star. Now it's time for our third star to die--this time more peacefully, to a white dwarf. This collection of debris encounters another star which ends up captured, the super-planet ending up in the life zone of the new star. The white dwarf sucks in matter from this fourth star, eventually you get a nova. This scours the atmosphere off the super-planet. You're now left with a super-planet with no atmosphere. It's going to be an incredibly dense world as much of the stuff thrown off from the neutron star impact is from the lower part of the periodic table. While you didn't ask for it this is going to be an immensely valuable source of heavy metals. (This is assuming it's worthwhile to ship such stuff. If you have a brute-force stardrive it probably isn't.) Note that this is a very dangerous star system to be in, the white dwarf will periodically nova (although a sufficiently advanced science should be able to predict the detonations) and if it sucks down enough matter it will be even worse when it collapses down to a neutron star. You also have the jets from the other neutron star or black hole, although they could be aimed in a safe direction. [Answer] **Heavy metal world.** 1. 12G planet. You could ramp up the gravity by making the core more dense. Our planet has an iron / nickel core under the rocks, and those have atomic weights of 55 and 58. Uranium has an atomic weight of 238. So if you made the core out of uranium and other heavy friends your density is 5x that of earth. Those elements are rarer than iron but not crazy rare. Now your planet only needs to be 2.4x as big as earth to have your 12G. If you want your planet even smaller, you can invoke the stable superheavy elements from the undiscovered far reaches of the periodic table - [the island of stability](https://en.wikipedia.org/wiki/Island_of_stability) There could be other cool things about the uranium planet. Maybe natural fission goes on deep inside, which would make for rocking volcanoes. Could you take advantage of this to get off planet? Hmm... Also, the atmosphere would have a lot of radon, which would give everyone very low voices among other things. 2. My understanding of atmosphere is that you need a magnetosphere to keep it in, gravity notwithstanding. Otherwise the solar wind will strip it away. Mars lost its magnetosphere and then lost its atmosphere because of that. No reason to think that the heavy planet would not have a magnetosphere. ]
[Question] [ Would heavier clothing solve the problem of bone and muscle loss in Martian gravity? It doesn't have to be a perfect solution, I just don't want my Martian colonists to be total wimps compared to Earthlings. [Answer] # No; probably Your skeletal muscles are not the most important muscles in your body. That would be your heart. Unless you can add weights your blood, then your heart will get weaker as you spend more time on Mars. The amount of force it takes to pump blood from your heart to your head depends on the hydrostatic force of blood at that vertical distance; so a this required force lowers, your heart gets weaker. This same argument would apply to any internal muscular structure in your body, and possibly some external ones as well. There are some things you just can't weight. As a second reason, the reasons for [astronaut's bone density loss in space](https://www.nasa.gov/audience/foreducators/postsecondary/features/F_Bones_in_Space.html) is not well understood. This mass loss is caused by calcium being removed from the bones into the blood, and it starts days after getting into space. Now, we don't really know if an extended stay on Mars at ~30% gravity will have the same effect, but we could probably assume that there will be some sort of effect. So in conclusion, even if you weighed your clothes perfectly to simulate the musculo-skeletal effect of being on Earth, your internal muscles, in particular your heart, will still be weaker; and your bones may still lose calcium due to some unknown effect of lowered gravity. [Answer] **Runners on Earth use weights for strength training** In fact, it's exactly what you're asking about. Joggers and runners use weights to increase their strength above what our local gravity can give them. I've personally used weights like these: [![enter image description here](https://i.stack.imgur.com/UakTQ.jpg)](https://i.stack.imgur.com/UakTQ.jpg) *Photo Courtesy [Amazon.com](https://rads.stackoverflow.com/amzn/click/com/B01MSROZO6).* Wrist weights and even [torso weights](https://www.walmart.com/ip/CROSS101-Adjustable-Weighted-Vest/53982696?wmlspartner=wlpa&selectedSellerId=2008&adid=22222222227047606899&wl0=&wl1=s&wl2=c&wl3=104203499537&wl4=pla-254857681907&wl5=9029826&wl6=&wl7=&wl8=&wl9=pla&wl10=113489946&wl11=online&wl12=53982696&wl13=&veh=sem) are also used. So, yes, certainly. Weights can be used to compensate for the loss of muscle due to lower gravity just as we use them to increase muscle in our native gravity. But it would be uncomfortable to use them all the time. And while weights like this can compensate for muscle loss, they can't compensate for your body's natural adaptation of heart, lung, and other internal organs to the lower gravity. Over time, no matter what you do, you will eventually become unable to return to Earth for long periods of time.1 --- 1 *You know, I say this, and lots of people will be willing to believe it... but humanity is remarkably adaptable. I wonder, really, if the 10th generation martians would actually have massive difficulties returning to Earth. I can see the point with [full weighlessness](https://www.space.com/21413-hadfield-astronaut-health-return-earth.html), but we really are good at adapting. I'm not willing to rule it out — at least not completely.* [Answer] weighted clothing may help some with your skeletal muscles but would not mitigate the effects on your circulatory system there however could be a few ways to change that when dealing with earth standard gravity your martians could wear extremely tight clothing on lower extremities for working periods kind of like a g-suit fighter pilots wear <https://en.wikipedia.org/wiki/G-suit> the other options is to as part of training for the trip complete a work out every day under increased gravity maybe in some type of turbine or centrifugal force machine or maybe have a space station just for the training. I think using a combination of the two along with the weighted clothing your martians may still experience some fatigue but it should be manageable. [Answer] It might help somewhat, but there are a lot of biological functions inside your body that won't like the low gravity. If we ignore those than yes, more weight would make them stronger, unlike more gravity which would hurt their innards and stuff. [Answer] I think using thin, but heavy weights on all pants and torso clothing, including the head as well, would help to mitigate the difference in gravity. For the internal organs, this would need to be investigated and protocols set up, either some type of physical workout or maybe drug therapy as an intervention to prevent or at least slow down the effects on the heart and other internal body organs. However, for now, I think most important of all is age of the astronauts. If we are going to send people to live for long periods on Mars, then start with people over 45 or 50, maybe even 60. You should eliminate the possibility of pregnancy until we learn more. Using older people also reduces risk to younger people, who may end up with permanent health damage, and end their life prematurely. An older person, usually has lived thru the years of starting and raising a family, so they would present with less risk to long term survival issues. After enough health data has been taken, then the age for living on Mars may be adjusted down, and couples could even have families on Mars. But first, see what the health risk is, before sending young couples and having their life cut short because of health issues. ]
[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/85713/edit). Closed 6 years ago. [Improve this question](/posts/85713/edit) Imagine the modern society, except all dead people spawned ghosts upon death. The ghost of the dead inherits memory and personality of its past living self, appear as translucent wraiths that can partially interact with the material world by blowing objects about as though a gust of wind. The ghosts have to consume "ghost-juice" or Ectoplasm to survive (as a ghost), they do this either by attacking and disintegrating another ghost then feasting upon its remains, or by absorbing the "soul" of a living human being. When a living human being's soul is consumed, nothing really harmful happens, except when a human with a weakened soul dies, the ghost that spawns from that person will be weak and may straight-up disintegrate upon "birth". (Souls are generated steadily by a living human being from infancy, and small losses can be recovered, but an ordinary person cannot generate more than 2 or 3 "ghost-worthy" amounts of Ectoplasm, while a ghost needs to consume an amount of Ectoplasm equal to itself every 50 years or so to stay healthy. Consuming more will make it stronger proportional to the amount of extra consumption.) Now, assuming no method of artificially creating Ectoplasm is available, will the human race become hostile towards the ghosts? (Manifested by researching methods to eliminate them) If so, why? Since the only reason a still-living person can be hostile towards ghosts is because the person wants to be a strong, healthy ghost themselves after death, which makes their loyalty to humanity necessarily short-lived. Also, would it be reasonable to expect that some rich or powerful people will continue their existences as ghosts after death and hire/coerce a bunch of humans to regularly "donate" their souls to them? Or would becoming a ghost automatically invalidate a person's status as a ruler? Can humans and ghosts eventually work out a sustainable situation? Elaboration: * There are no ghosts belonging people who had died before the year of 2016, that was the original idea. * "Strength" describes mostly a ghost's ability to kill other ghosts. * Ghosts can "die" from attack by other ghosts, Ectoplasm-starvation or mental degeneration, all of which leads to it exploding into a cloud of Ectoplasm. * Ghosts can easily communicate with living human by whispering or doing sign-language (they can't speak loudly due to limited interaction with air.) Supposedly, stronger ghosts will be larger and "denser", allowing greater, though never as complete interaction with ordinary objects as compared to real human. [Answer] Situation You describe is inherently unstable unless You put an upper limit to the amount of "ectoplasm" each ghost can consume. Without this restraint there would be a full scale war between ghosts leaving just a one alive in each "zone" who will roam it and consume all "newborns" (obviously weaker) as soon as they emerge. Dimensions of the "zone" would be only dependent on how fast, efficient and relentless this super-ghost may be to his task. In this situation "living" task would be to preserve their own "ghostiness" and also to shield it after birth/death. You have better to introduce some kind of "ghost indigestion" refraining ghosts to consume *more* than a "soul" every 50 years. [Answer] # No If they exist, someone will find a way to kill them. Humanity doesn't exist peacefully alongside any thing or any one. There is nothing we have encountered that we haven't found a way to kill. Why would these ghosts be any different? [Answer] In the current scenario, there would be 100 billion ghosts to only 7 billion living humans. Therefore **107 billion** \* **2.5** Ectoplasm = **267.5** units of Ectoplasm. The rate at which Ectoplasm is consumed by the ghosts will far outnumber the rate at which Ectoplasm is being created. In the first 50 years, the ghosts will have consumed the Ectoplasm at a rate which would imbalance the food chain thereby causing anarchy and then total destruction. [Human-ghost-population-ratio](https://www.livescience.com/18336-human-population-dead-living-infographic.html) [Answer] We'd all be still serving the ghost of some ruler of old. Possibly Genghis Khan. Violent regimes sometimes get very stable, but death is inevitable, and you can always count on succession conflicts to eventually shake things up. If we had a means of immortality as easy for the powerful as cannibalizing some peasant every 50 years, that removes the source of instability. The still-living nobility invested in the old order will still obey their dead ruler, assuming communication is still possible. Their services can be rewarded with something less than full immortality, to avoid unsustainable dynamics. They live 1000, 500, 300, 200, 100, or 50 years as ghosts, according to rank. The underclass is large enough to sustain the nobles' rewards, and no peasant ever lives as a ghost. The only one truly immortal is the one emperor. So, worldwide, stable empire. Whether to call that "peace" is subjective. On one hand, repression and privilege. On the other hand, no wars. [Answer] The whole system is extremely unstable. Ghosts being able to consume others to not just sustain themselves, but make themselves stronger implies that sooner or later a soul hungry for power will consume more and more ghosts, while nothing would stop it from consuming humans in particular at the end of their life-span. As Nishanth Menon has already pointed out, there is by far not enough ectoplasm to support all ghosts. Before long, humans would have to be hostile and find ways to defend themselves or even destroy the souls of 'known' greedy and power-hungry persons directly after death as long as they are still week to prevent such a secnario. [Answer] it sounds like living humans are helpless against ghosts, but ghosts can fight each other. as such, **ghosts would protect the living souls the way we protect children**. similarly, i imagine ghosts would continue to own their property the same way that the elderly continue to own their property. they may not be able to physically stop you from taking it, but other **living people will defend ghost's property rights** to ensure their own property is not taken upon their death. if it is no more difficult to detect and punish soul theft than it is to detect and punish child abuse, then **ghosts would probably be welcomed in polite society as well as any adult man**. on the other hand, if detecting soul theft is much harder (e.g. because ghosts can walk thru walls), then **ghosts might be banned from human settlements**. even still, interaction would probably be peaceful. this answer assumes ghosts have normal human motivations. if you modified your question to suggest ghosts had an overwhelming hunger for souls, then the outcome would be quite different.... [Answer] **The fact:** * No one (almost\*) would live forever. Thus, all people (or the majority) must accept this. Human 'Ectoplasm' cannot feed all ghost population forever. Therefore, some ghost must die. Ghost can kill human by eat all their Ectoplasm (effectively kill human when they actually die). Human can kill ghost with some 'special weapon'. In this war, **human gain upper hand**. Because when human kill ghost, ghost die. But when ghost 'eat' human, human does not die immediately. He will die until he 'die' as a ghost. So, he can stand an kill many ghost. Now, ghost must negotiate with human to exist. **Solution:** In this situation, the [social contract](http://www.dictionary.com/browse/social-contract) is required to keep everything in place. Government law can work too, but it have to begin with social contract. 'Ghost life' can be view as a part of human life. Well, consider when a people become 'ghost', he 'retired' from physical work (like you quit a job). Let's view at 'in labor' and 'retired people' in real world. In labor population have to support retired population by some mean, direct (son support his old mom) or indirect (government via tax of in labor population). By any mean, however, retired population depend on in labor population to stay alive (or starving). Let's apply 'in labor' = alive as human, 'retired' as ghost. Direct support: family feed their love one so they can stay longer. For example, a husband loss his wife in car accident. He feed his wife, so they can stay together. He have enough 'food' for his wife until he 100 year old and die (as you said, 1 human = 2 ghost-food of 50 years). Indirect support: Company paid for Ectoplasm to feed their worthy employee (with a lot of $, you can buy anything). Government tax Ectoplasm to feed their great leader (suitable for Communism or so). Some crime may happen, live living people kidnap human to feed their 'ghost'. This is similar with [Organ theft](https://en.wikipedia.org/wiki/Organ_theft). How we deal with them may similar to what our real world do with organ theft. [Answer] I believe it's possible to keep a sustainable system and still making the balance delicate enough to allow for interesting stories to develop in your world. Ghosts will eventually realize that they depend on the living to keep their existence; so it is likely that responsible ghosts will want to keep the living people with healthy souls to grow and consume later. I'm going to sound a little cheesy with this, but imagine there is a way for ghosts to "farm" living people's ectoplasm. For instance, by making the living live richer experiences filled with strong emotions, their ectoplasm level could increase, allowing the ghosts to profit from the surplus. In that sense, "evil" ghosts could farm people by causing fear and "good" spirits could help the living by communicating about opportunities and transferring knowledge. Responsible ghosts can fight power thirsty ones, while evil ghosts can fight good ghosts for territory. Living people will likely side with whichever kind of ghost they prefer. Powerful or evil ghosts could ally with living individuals to gather living people in exchange of favors. Nice ghosts could likely roam around their living families to enrich their lives and keep evil ghosts away if in enough numbers. ]
[Question] [ I'm working on a fantasy/sci-fi story set on Earth but in the far future. Hundreds of millions of years from now, after the rise and fall of many civilisations, the world has gone back to a medieval-like society, but relics can be found from ages past that are capable of amazing things: hovercrafts, laser weapons etc. I'd like to design the map for this world, but I am unaware of what would affect the continents other than continental drift. I would like some idea of what the future continents or super continents would look like. [Answer] ## Forces of creation * **Volcanism.** Volcanoes and similar tectonic activity can produce surprisingly large landforms - take a look at Japan and Hawaii. This is most common in ocean [subduction zones](http://www.livescience.com/43220-subduction-zone-definition.html) but it may be possible to build more land this way above the sea. * **Convergent plate movement.** You can get some pretty large mountain ranges by smushing together existing chunks of land - take, for example, the [Tibetan Plateau](https://en.wikipedia.org/wiki/Tibetan_Plateau), home to the world's tallest mountain. This is related to continental drift, as are many ideas presented here, but it is a complicated phenomenon that will produce many results. * **Matter from space.** This not likely, and it's really only happened on a large scale [once](https://en.wikipedia.org/wiki/Late_Heavy_Bombardment), but a planetary-sized event could send a whole lotta stuff down. This also counts as destructive. * **Living things.** Life has completely [changed the Earth's atmosphere](https://en.wikipedia.org/wiki/Great_Oxygenation_Event) (also building up massive piles of iron sediment in the process), created [massive deposits underground](https://en.wikipedia.org/wiki/Oil_field), [massive deposits aboveground](https://en.wikipedia.org/wiki/Karst), and changed the color of the planet as seen from space (hint: it's green now). It is reasonable to believe similar changes may occur in the future. ## Forces of destruction * **Weathering and erosion.** Wind, water, plants, and other phenomena can break down the land, often in dramatic ways. This has given us the [Grand Canyon](http://www.thecanyon.com/), among other things. * **Subduction.** The continents don't just drift! Material can be [re-absorbed](http://www.universetoday.com/43822/subduction-zone/) over time, as it has been for billions of years. * **Glaciers.** Ice ages are unpredictable and poorly understood. If one were to occur, we could see glaciers carving up the terrain. ## Neutral * **Rising sea levels.** If human emissions continue, the climate will continue to change. The poles will shrink, and the sea will slowly overcome the land. There are some [pretty good simulators](https://calculatedearth.com/) for this. * **Sinking sea levels.** If the Earth cools, water will be trapped in ice, lowering the sea level. * **Transform plate movement.** [This](http://www.cotf.edu/ete/modules/msese/earthsysflr/plates4.html) can shift the locations of land masses greatly over time. * **Divergent plate movement.** Playing on the "continents are complicated" idea, it's entirely possible for continents to split apart, just as they can push together or move around. This is why the [Atlantic Ocean is getting larger](https://en.wikipedia.org/wiki/Mid-Atlantic_Ridge), and why the [African continent will soon split in two](https://en.wikipedia.org/wiki/Great_Rift_Valley). --- Many of these forces are complex, and you don't have to consider them all. Consider one of the most commonly suggested [supercontinents](https://en.wikipedia.org/wiki/Supercontinent), and play with it: | [Pangaea Ultima](https://en.wikipedia.org/wiki/Pangaea_Ultima) | [Amasia](https://en.wikipedia.org/wiki/Amasia_(continent)) | [Novopangaea](https://en.wikipedia.org/wiki/Novopangaea) | [Answer] Even hundreds of millions of years in the future the Earth might still be in the Quaternary Ice Age which only started 2.6 million years ago. Currently we are in an intergalacial period. Anthropogenic warming will delay the onset of the next glacial phase for, possibly, another one hundred thousand years. Most likely this will only be a brief hiatus for the Quaternary Ice Age. It is useful to look at the history of the [Ice Ages](https://en.wikipedia.org/wiki/Timeline_of_glaciation) to understand what might happen hundreds of millions of years in the future with respect to glaciation. > > The Earth is passing through an ice age known as the quaternary glaciation, and is presently in the Holocene interglacial period. This period would normally be expected to end in about 25,000 years.[34] However, the increased rate of carbon dioxide release into the atmosphere by humans may delay the onset of the next glacial period until at least 50,000–130,000 years from now. On the other hand, a global warming period of finite duration (based on the assumption that fossil fuel use will cease by the year 2200) will probably only impact the glacial period for about 5,000 years. Thus, a brief period of global warming induced through a few centuries worth of greenhouse gas emission would only have a limited impact in the long term. > > > Please note this source differs in its estimate of the impact of global warming from this answer. That estimate was based on Curt Stager's book *Deep Future*: The Next 100,00 Years of Life Earth (2011). Who said predicting the future was easy? A considerable number of factors affecting the future of the Earth can be discovered [here](https://en.wikipedia.org/wiki/Future_of_Earth). This to summarize concisely, but here are some of the salient factors. ## Human Influence > > Humans play a key role in the biosphere, with the large human population dominating many of Earth's ecosystems.[3](https://i.stack.imgur.com/xUA0W.png) This has resulted in a widespread, ongoing mass extinction of other species during the present geological epoch, now known as the Holocene extinction. The large-scale loss of species caused by human influence since the 1950s has been called a biotic crisis, with an estimated 10% of the total species lost as of 2007.[6] At current rates, about 30% of species are at risk of extinction in the next hundred years.[15] The Holocene extinction event is the result of habitat destruction, the widespread distribution of invasive species, hunting, and climate change.[16][17] In the present day, human activity has had a significant impact on the surface of the planet. More than a third of the land surface has been modified by human actions, and humans use about 20% of global primary production.[4] The concentration of carbon dioxide in the atmosphere has increased by close to 30% since the start of the Industrial Revolution. > > > ## Random Events These include asteroid or comet collisions, nearby supernovas, and a gamma-ray burster pointing at the solar system. It might include unforeseen technological events causing massive environmental degradation, the rearrangement of the Earth's surface, and the extinction of the human species All of which are unpredictable and, obviously, do not follow any long-term trends which is a useful for any reasonable futurological exercise. ## Geodynamics The following geological events will occur in the relative near fture compared to your hundreds of megayears timescale. But hey give an indication of what a dynamic geological system can produce over sufficiently long timescales. > > Tectonics-based events will continue to occur well into the future and the surface will be steadily reshaped by tectonic uplift, extrusions, and erosion. Mount Vesuvius can be expected to erupt about 40 times over the next 1,000 years. During the same period, about five to seven earthquakes of magnitude 8 or greater should occur along the San Andreas Fault, while about 50 magnitude 9 events may be expected worldwide. Mauna Loa should experience about 200 eruptions over the next 1,000 years, and the Old Faithful Geyser will likely cease to operate. The Niagara Falls will continue to retreat upstream, reaching Buffalo in about 30,000–50,000 years.[9] > > > In 10,000 years, the post-glacial rebound of the Baltic Sea will have > reduced the depth by about 90 m (300 ft). The Hudson Bay will decrease > in depth by 100 m over the same period.[30] After 100,000 years, the > island of Hawaii will have shifted about 9 km (5.6 mi) to the > northwest. The planet may be entering another glacial period by this > time. > > > ## Continental Drift This is driven a combination of subduction and the presence of a hydrosphere (a fancy way of says Earth has seas and oceans on its surface). The arrangement of land masses progressively undergoes change. The longer the timescale the more massive this changes will be. > > At present, the continents of North and South America are moving > westward from Africa and Europe. Researchers have produced several > scenarios about how this will continue in the future.[46] These > geodynamic models can be distinguished by the subduction flux, whereby > the oceanic crust moves under a continent. In the introversion model, > the younger, interior, Atlantic ocean becomes preferentially subducted > and the current migration of North and South America is reversed. In > the extroversion model, the older, exterior, Pacific ocean remains > preferentially subducted and North and South America migrate toward > eastern Asia.[47][48] > > > As the understanding of geodynamics improves, these models will be > subject to revision. In 2008, for example, a computer simulation was > used to predict that a reorganization of the mantle convection will > occur over the next 100 million years, causing a supercontinent > composed of Africa, Eurasia, Australia, Antarctica and South America > to form around Antarctica. > > > [![This is an image of Pangea Ultima the predicted future super-continent](https://i.stack.imgur.com/xUA0W.png)](https://i.stack.imgur.com/xUA0W.png) The above image of Pangea Ultima a predicted future super-continent. > > 50 million years from now the Mediterranean sea may vanish and the collision between Europe and Africa will create a long mountain range extending to the current location of the Persian Gulf. Australia will merge with Indonesia, and Baja California will slide northward along the coast. New subduction zones may appear off the eastern coast of North and South America, and mountain chains will form along those coastlines. To the south, the migration of Antarctica to the north will cause all of its ice sheets to melt. This, along with the melting of the Greenland ice sheets, will raise the average ocean level by 90 m (300 ft). The inland flooding of the continents will result in climate changes.[46] > > > As this scenario continues, by 100 million years from the present the > continental spreading will have reached its maximum extent and the > continents will then begin to coalesce. In 250 million years, North > America will collide with Africa while South America will wrap around > the southern tip of Africa. The result will be the formation of a new > supercontinent (sometimes called Pangaea Ultima), with the Pacific > Ocean stretching across half the planet. The continent of Antarctica > will reverse direction and return to the South Pole, building up a new > ice cap. > > > This based on one of three models for the formation of a future super-continent (in this case the introversion model). The subduction flux model led to this possible future supercontinent > > a computer simulation was used to predict that a reorganization of the mantle convection will occur over the next 100 million years, causing a supercontinent composed of Africa, Eurasia, Australia, Antarctica and South America to form around Antarctica. > > > While the extroversion model of continental drift gave this future. > > predicted that the continents of North and South America would continue to advance across the Pacific Ocean, pivoting about Siberia until they begin to merge with Asia. He dubbed the resulting supercontinent, Amasia.[52][53] Later, in the 1990s, Roy Livermore calculated a similar scenario. He predicted that Antarctica would start to migrate northward, and east Africa and Madagascar would move across the Indian Ocean to collide with Asia.[54] > > > In an extroversion model, the closure of the Pacific Ocean would be > complete in about 350 million years.[55] This marks the completion of > the current supercontinent cycle, wherein the continents split apart > and then rejoin each other about every 400–500 million years.[56] Once > the supercontinent is built, plate tectonics may enter a period of > inactivity as the rate of subduction drops by an order of magnitude. > This period of stability could cause an increase in the mantle > temperature at the rate of 30–100 °C (54–180 °F) every 100 million > years, which is the minimum lifetime of past supercontinents. As a > consequence, volcanic activity may increase > > > The formation of a supercontinent will be main event that will sahpe the face of the Earth. Since there are three models of continental drift each predicting their own version of a future supercontinent the only recommendation that can be made to the OP is choose the one that suits your story best and go with it. The general changes to planet Earth over next few hundreds of millions of years which impact on life on the planet and which will influence factors concerning its cartography. many of which need to be taken into account with respect to their impact on any human inhabitants. > > Over time intervals of hundreds of millions of years, random celestial events pose a global risk to the biosphere, which can result in mass extinctions. These include impacts by comets or asteroids with diameters of 5–10 km (3.1–6.2 mi) or more, and the possibility of a massive stellar explosion, called a supernova, within a 100-light-year radius of the Sun, called a Near-Earth supernova. Other large-scale geological events are more predictable. If the long-term effects of global warming are disregarded, Milankovitch theory predicts that the planet will continue to undergo glacial periods at least until the Quaternary glaciation comes to an end. These periods are caused by eccentricity, axial tilt, and precession of the Earth's orbit.[10] As part of the ongoing supercontinent cycle, plate tectonics will probably result in a supercontinent in 250–350 million years. > > > [Answer] The future of Earth is most likely to continue to be shaped by natural forces, especially if civilizations rise and fall over the course of time. Even far future predictions like "[The Future is Wild](http://www.thefutureiswild.com/documentary/)" only go about 200 mega years into the future, after that there is enough randomness to cause predictions to simply fail. Even a mere 5 million years into the future, if humanity survives at all it will probably have evolved into post-post-post humanity (our species can be reliably traced back to about 5 million years ago, and hominids have undergone a tremendous amount of change during that time). Depending on your views of the "Singularity" and post humanity, it is quite plausible in story terms to simply posit that super intelligent AI's or post humans reshaped the Earth to their liking, having the ability to discover principles in physics, chemistry and biology that allowed them to do this easily and (relatively) cheaply. Given the enormous amount of energy that even a [small earthquake or volcano can release](http://www.projectrho.com/public_html/rocket/usefultables.php), clearly the post humans have access to the ability to control huge amounts of energy and apply it in a controlled and non destructive fashion. What this would look like long afterwards is almost impossible to visualize. Any post human civilization would probably want to maximize the ability to use all the 195 Petawatts of solar energy that strikes the Earth, so plants and animals may have been replaced long ago with some sort of artificial biosphere (technosphere) dedicated to harvesting and processing solar energy. Spidery silicon "plants" might make up most of the ground coverage on Earth in this time, and of course after millions of years, the operating instructions would have randomized and "mutated" into things far different than their long ago creators imagined. Rather than travel, post humans may have become sessile, and developed a web of connections between each other and other "beings" in their technosphere, leaving a web of artificial nerve fibres joining nodes all across the landscape. Post humans would recognize that the Earth might become uninhabitable in 500 million to one billion years in the future as the Sun gradually increases its output, so the sky might be filled with some sort of obscurant to reflect excess solar energy back into space, or there are billions of tiny mirrors in orbit, or the planet itself has been moved into a larger orbit to reduce the solar energy and keep the planet cool. If the system is still working to adjust the orbit of Earth, the night sky has a spectacular show as asteroids periodically make close passes by the Earth to exchange momentum and push the Earth farther out from the Sun. The Moon may or may not be affected by this, depending on the desires of the post humans who built the system. If the post humans adjusted the orbit of the Earth, it is also quite possible they moved other planets around, so the night sky may well be unrecognizable. If they used [Star Lifting](https://www.youtube.com/watch?v=pzuHxL5FD5U) to mine matter from the Sun rather than adjust the orbit of the Earth, there may be Uranus sized artificial gas giants in the sky, originally "built" to house the hydrogen "mined" from the now cooler Sun. And of course the most spectacular object filling the night sky might well be the [Matrioshka Brains](https://www.youtube.com/watch?v=Ef-mxjYkllw&index=11&list=PLIIOUpOge0LtW77TNvgrWWu5OC3EOwqxQ) surrounding the Sun and expanding outwards into deep space..... [Answer] The answers so far have not included climate effects nor the effects of the rise and fall of civilizations, in that amount of time there is a decent chance that non-human species would rise to sentience. By climate I refer to world circling effects like the wind carrying the Sahara over to South America to improve the soil of the Amazon basin. If something happens to change or stop the Gulf Stream all of Northern Europe will be much less habitable than it is now. The effects of El Niño on Central and South America .. etc. The effects of civilisaton .. does anyone build a space elevator in that time? Do we import asteriods to replace resources used up by over mining/ extracting? Does an ocean get revamped to produce algea as a basis for food production, and then get reclaimed as “natural” ocean .. do the tree huggers ever establish a world side ban on logging .. so that trees overgrow the world? Then do they get logged off in reaction over the next few hundred centuries? Does genetic modification replace evolution as the driver to create new species? There is no limit to the global effects that mankind can create over the time span of your question. ]
[Question] [ A quest line in my game features the kidnapping of someone from *The Hotlands* to an area known as *The Ice Hills*. The people from *The Hotlands* require a hot body temperature to function correctly, and mostly live in volcanic areas where temperatures can easily reach boiling point (100 °C [212° F]). They can function, although badly, down to around 15 °C(59° F). The people from *The Ice Hills* are the very opposite where they require an extreme cold body temperature to function and survive. They mostly live in areas of around -2 °C(28.4° F) but, they can function, badly, at up to 20 °C(68° F). There are also *Middle-Worlders* who are like normal people. The other two people find it difficult to trust the *Middle-Worlders*. (Even though they run the forges and smith items for the people of *The Ice Hills*.) Using technology from the dark ages how can they keep him above 15 °C(59° F) so he doesn't die but, below 20 °C(68° F) so the people of *The Ice Hills* can speak with him. I want to refrain from using magic if possible. So far I can only think of lighting fires in some sort of greenhouse. [Answer] If the Hotlanders are warm-blooded, then given enough animal skins, food, and fire, they should be able to endure the cold. We humans like to live around 21C, but routinely endure -17C with proper attire and shelter. The Ice Hill people have a house. In the house, they've built two rooms. The first room has a fireplace with a raging fire. The second room has no fire. When they want to converse with the Hotlander, he exits his comfortable room, dons animal skins, and walks through the door in to the colder section of the house. The colder section would be warmer than the Ice Hill people like, cooler than the Hotlander likes but it would be survivable for both. [Answer] # Assuming both people thermoregulate, no problem Mammals and birds are endothermic, meaning that they create the heat they need to maintain their body temperatures inside them. Since they require a specific body temperature to live, these animals must also be able to cool themselves. For the Hot-heads, heating themselves should be no problem. If their body maintains its own body temperature, then all they have to do is wear a polar bear-worth of skins and they should be fine. Their body will generate heat as needed until it is at the correct temperature. The Ice-queens will have a bit more trouble, depending on how cold they need their internal body temperature to be. Human body temperature is around 37 C, which is generally hotter than the daily average temperature anywhere on Earth. Humans are almost always able to shed heat to the environment because the environment is colder than their body. Humans also sweat to drop the extra heat. The Ice-folk probably won't be able to sweat; since their typical environment is below freezing sweating wouldn't do much good. I would assume that applying ice/snow to themselves would be their preferred method of cooling down and maintaining their preferred body temp. Therefore, in order to meet each other, the people should interact in a cool enviornment more suitable to the Ice-kins, and the Hot-ites need to bundle up. [Answer] 1. Igloos 2. Caves I should have noted that I assumed the hotlanders were cold-blooded due to their major struggles with the cold. This may not necessarily they're as cold-blooded as earth reptiles, but colder than earth's warm-blooded animals. Of course, you'll need a fire of some sort, but if you can vent the smoke and can keep the opening protected, you can make it comfortably warm in a number of different settings even with medieval tech because we've been keeping ourselves warm in cold settings for millennia. [Answer] As already mentioned, igloos are good. But not just any igloo will do. Most cartoon and "common man" igloos are just domes with a side opening. It should look like a dome without an opening. The entrance should be designed like a hole dug under a fence. It should go under the side of the dome's wall. In other words the only way to the igloo should be from below the floor level. Why, you ask? Because thermodynamics. Secondly, one should stay as near as possible to the top of the dome to keep warm. Warm air goes up and cold air down, so there should be an elevated stand where to sleep and/or stay. In temperate environments staying cool requires a supply of cool fluid. Water conducts heat well. But how to get cool air? Solution: a hut with a cone-shaped roof and a *long* chimney in the middle. It allows for the warm air to rise up and not gather in the hut itself. In this case you actually want to enter the hut from above the floor level to trap cool air in. [Answer] There is one more possibility,hot springs,cracks in the surface exposing a dormant volcano,he could (stand inside a cave ) talk across a crevasse and the ice people could stand outside and talk all they like,they could also toss in food/offerings depending on how that person is set up [Answer] The Ancestors knew how to keep warm with neolithic technology during the ice age over 20,000 years ago, so devising insulating clothing, insulating shelters (both temporary and permanent) and high calorie foods like Pemmican or eating blubber will help fuel the metabolic engines. Insulation is generally done by having still air pockets, so insulating clothing can be made from sheets of grass woven together at a minimum, although gathering down and trapping it between two layers of fabric or wearing fur is far superior. Since down coats become useless when wet, while fur sheds water and snow, fur is by far the preferred option. [![enter image description here](https://i.stack.imgur.com/mw8cn.jpg)](https://i.stack.imgur.com/mw8cn.jpg) *Otzi the iceman went out onto a glacier dressed like this* This goes for other things as well. Temporary show shelters can be created by digging into fresh snow so the fluffy texture acts as insulation. Layers of branches or grass between you and the ground reduce heat loss as well. More permanent shelters will be or resemble igloos, and a National Film Board documentary on how to build a real igloo is [here](https://www.youtube.com/watch?v=K3pd-wxNEKQ) So the main issue in your scenario is the people from the hot zone will require more insulation, and will need to be fed more food or more often in order to remain warm in the arctic. Since this sort of environment has been lived in by our own human Ancestors for 20,000+ years, this really shouldn't be much of an issue, unless the cold people decide not to expend the extra resources to do so. ]
[Question] [ The setting: A pre-industrial fantasy setting where magic is probably available, but not necessarily (*outside the god's capabilities anyway*). There are known to be different Gods, with different personalities, in charge of different aspects of human life. These Gods can physically affect the world in certain ways and in some cases, this might negatively impact some people while positively affecting others. Some Gods are not happy with only the aspect they currently control, and they have different temperaments. For instance, there generally is a God who grants power and is a God of chaos or destruction. For obvious reasons, worshipping this God is not a highly regarded trait - but there are even some rivalries between "good-natured" Gods. How might a society work which grants "Freedom of Religion" (*by today's standards - even Aztecs would not be allowed to sacrifice people*) to its members? Can such a thing exist? Keep in mind that even some "good-natured" Gods are in conflict with other "good-natured" Gods, so what societal laws might there be for keeping the balance in comparison to today's laws? [Answer] Probably in a "You can worship whatever god you want how you need to, just so long as it doesn't affect someone else's freedom." This would annoy the Aztecs, but the rest of the people would be happy with not being ritually murdered. The interesting question isn't really how this would affect the people, but what the gods would do about it. For instance, if I'm a chaos god that likes offerings of the still beating hearts of my worshiper's enemies, I'm not going to be to happy with some lowly humans telling people they can't. And unless some other god is willing to step in and stop me, I have the power to do things to get what I want. If I'm a jealous god that doesn't want anyone else worshiped, then what might I do to the priests and followers of other gods? You'd almost need a freedom of religion law among the gods themselves, and some way to enforce it, which could be another source of contention among even the good-natured gods. [Answer] The obvious example that comes to mind would be Forgotten Realms (D&D) ...they have [A LOT of gods](https://en.wikipedia.org/wiki/List_of_Forgotten_Realms_deities) and they vary in how they treat the world and their followers. It is easy to imagine a city in [Forgotten Realms](https://en.wikipedia.org/wiki/Forgotten_Realms), maybe [Waterdeep](https://en.wikipedia.org/wiki/Waterdeep) (a large metropolis) where there are no laws regarding worship. People are free to worship any deity they choose and the deities can fall anywhere on the 9 point alignment axis. [![enter image description here](https://i.stack.imgur.com/xGfkD.png)](https://i.stack.imgur.com/xGfkD.png) It is important at this point to differentiate between legal freedom and complete freedom. Much like the second amendment and freedom of speech, you are protected from government punishment based solely on what you say...[but as pointed out](http://imgs.xkcd.com/comics/free_speech.png), that does not protect you from the implications of obnoxious things you might say and how other people feel about your opinions. I would suggest that freedom of religion in this sort of world would work much the same way. Sure you are free to worship the *chaotic evil god of murder* if you want to...[but doing so in public could end very very poorly for you](http://static.deathandtaxesmag.com/uploads/2015/06/witch-burning.jpg), even if it is not the government that is making things end that way. Odds are there would be cultural norms for a given city where a certain set of gods is preferred, there would be a second layer of gods that while not common are not overtly frowned upon (maybe foreign deities or the deities of minority races) and then there would be the third layer of hated, feared, evil deities that are only worshipped in secret. You may not have the city guard executing mid-night raids but you could very well have mobs that take matters into their own hands...which the government may or may not tolerate. [Answer] Well of course almost any religious believer would say that the God or gods he believes in DO affect the world. So how is what you are suggesting different from real life? (a) There is no question or ambiguity? The gods come down from Mount Olympus on fiery chariots and throw lightning bolts and their enemies, and there is no way that anyone who is not blind could say that this was not done by the gods? And they do this often enough that pretty much everyone in the world sees it regularly? (As opposed to Judaism, Christianity, and Islam, which say that God usually works in more subtle ways, and that "blatant" miracles are relatively rare so that most people only know about them by reading scripture, lives of saints, etc, not personal experience.) (b) There are multiple competing gods? Like in Graceo-Roman polytheism. (Modern Hinduism has many gods of course, but I don't know enough about Hinduism to say if the believe the gods compete and fight like the Greek gods.) I can see how (a) and/or (b) could put a strain on freedom of religion. In the real world, an atheist might be annoyed at Christian prayers, but he presumably is not literally afraid that the Christian prayers will result in God bringing down some judgement on him, because he doesn't believe there is a God to do so. But if the existence of these gods was undeniable, then knowing that my neighbor who worships the cow god is praying for judgement on all those who eat beef, I would not dismiss his prayers as vain appeals to an imaginary god. I'd have a real fear that his god would respond and do me harm. In the real world, if someone worships a different god than mine, I generally believe that his prayers and rituals are just a waste of time. They don't do me any direct harm. (Barring special cases, like he kidnaps me to offer me as a human sacrifice.) But in your proposed scenario, he very well might do me harm. So in the real world, it makes good rational sense to say, let everyone worship in his own way, and attempt to persuade others that his way is best if he so chooses, and see what works out. But in your scenario, you can't just "live and let live". It's not that they're worshipping a false god, it's that they're worshipping a very real god who is inimical to me. To the extent that the gods compete, I think freedom of religion would become very difficult to sustain. It would be too impractical. Like, I have no problem being tolerant of people with different skin colors or languages or favorite foods. But I do have a problem with being tolerant of people who steal and kill. If the gods do not compete, if they're all friendly to each other and tell their followers to respect each other, than all this goes away, and freedom of religion becomes like accepting that some people like pizza and some like tacos. There's no reason why I should care if your tastes are different from mine. [Answer] I don't think the concept of 'freedom' can exist at all in a world that contains gods. Just because your country tells you you can eat meat on a Sunday doesn't mean you won't get fried by a divine lightning bolt after doing so. The Gods effectively control the executive branch of government, doling out punishments and rewards as they see fit. Without any checks and balances, their control will overshadow all other governments, making any human institution just a figurehead. That's why many kings of old said they ruled by 'divine right': Christians aren't supposed to swear loyalty to anyone but God, but since the king *works* for God, it's kind of the same. Based on this, any people in your world should be considered citizens of a dictatorship. Or, I guess an oligarchy since there's a bunch of gods. The main idea is that whatever 'freedoms' the humans have are based on what the gods let them do. That includes religion. However, I will say that religion in this case can be considered a form of bribery: butter up to the higher-ups and you might get some extra benefits. Thus, some factions may force people to worship certain gods, just like gangsters try to influence government by forcing people in their neighborhoods to vote a certain way. But again, this all depends on how well the gods are paying attention. [Answer] IMHO, both concepts of "religion" and "god" in such a world would be very different to what we imagine/know as such. To worship, for example, would be less about faith and belief (on an unseen/indirectly experienced higher being) and more about allegiance (towards a very visible individual). The legal system of societies developing in such a world would also be very different, with some societies being tied to the worship of/allegiance towards one or several gods, other societies giving their citizen complete freedom and responsibility over their choice of gods, and others simply not taking any stance. It would depend a lot on how strong the relationship can become between an individual and a god, and the nature of the gods themselves. For example, in a "Gods Need Prayer Badly" scenario, the gods would be as interested in maintaining a strong following as the people would be in keeping this god's favor. Other scenarios would put the people more or less at the mercy of the gods' whim, although god-challenging heroes may be a possibility. Of course, some people may take a third option, and flat out refuse to worship any visible, moody, aspect-limited, one-among-many, flawed "god", only willing to offer their souls to a believed One Supreme Being that would be above all gods and all creation. Maybe. [Answer] Simple: The gods might care about their power over the people, but not about being worshipped by them. In that case, those gods would probably treat us similar to like we treat wild animals: As long as they don't get in our way, we mostly don't care about them. Some we like to watch, others we more or less ignore. Sometimes we take a few exemplars to study them, or put them in zoos, or use them for other purposes (we of course also eat them sometimes; I guess that would not apply to your gods — but then, gods that want human sacrifice are not unheard of, so so why not also gods that eat humans). But otherwise, the animals are mostly affected by us indirectly (but still often massively), by our actions affecting their environment. [Answer] **The trick is to keep your head down and hope that you don't come to the notice of the gods.** A good read is [Ovid](http://classics.mit.edu/Ovid/metam.html). He introduces some rules like: > > no god may undo what another god has done > > > The general theme of the book is that if the gods notice you, you've had it. Jupiter likes nymphs who are willing to put out, if they won't, he turns them into something. Juno (Jupiter's wife) turns them into something if they put out. The only way out of this is to swear off sex forever (Diana) and get the protection of another god, or just hope that none of them ever notice you exist. You're free to worship whoever you like, and whoever you like had better be the local god. Fervently enough that the other people can see you doing it but not so fervently that any of the gods actually notice you. Freedom to do what you must to preserve your own skin, preferably in the same shape it currently is. As the great Pterry said, > > May you live in interesting times > > > [Answer] ## Freedom of religion would be in existence by definition. There would be no debate as to which gods exist, and which gods don't. They would all exert too much influence for their existence to be controversial. The study of their culture, behaviour, powers, etc. would no longer be considered religion and instead will form a major part of various sciences (like physics, psychology) and social sciences (like political science, anthropology), etc. We would also have new philosophical subjects like morality to be considered sciences, because there may be a universal consensus on what laws one must obey (if any) to be considered morally right, and what the consequences are to morally wrong actions. If there do exist some controversial points - for example, how bad-tempered is the God of Anger in emergency situations - then people would predict answers using scientific methods (hypotheses, then experiments, and then theories/facts) rather than personal opinions. Some limited differences of opinion would always be there, but that is present even among the scientists of today. ]
[Question] [ One thing I've always had trouble with when building a world is developing cultural myths and beliefs that feel unique and special from Earthly culture. Specifically, animals' meanings. In Christianity, for example, a snake is a symbol of evil. In America, the eagle is a sign of freedom, Etc. I need my myths to feel realistic. What process can we use to create animals meanings? What leads cultures to choose specific animals for specific meanings? [All Culturally Correct Questions](https://worldbuilding.meta.stackexchange.com/questions/3960/culturally-correct-series/3961#3961) [Answer] # What makes an animal a good candidate for gaining a special meaning? The most important point is: Notability. It must be an animal that is, or was at the time the myth was formed, something people would notice. That is, it has to be fairly common, and also in some way special. It may be that it is useful (like animals you eat). It maybe it is dangerous. It may be that it is a sign for important dates or events (think of migrating birds returning in spring, indicating the end of the winter). It may be that it is a rather impressive sight (like the eagle). It may be that it has some extraordinary abilities. It may be that it has some extraordinary feature which asks for explanation. Or for people coming to a new place (for example, the elements), it may be an animal that is different to the animals known from the old place. # How is the meaning assigned to animals? Here several sources are possible: * Typical (real or perceived) traits of the animal. For example, the pig likes to wallow in mud (it's both a way to regulate body temperature as pigs can't sweat, and a way to deal with parasites). That's why pigs are perceived as dirty animals. In addition, the meat of pigs can easily cause illnesses if not treated right, which adds to the perception of dirtiness (dirt makes you ill, so pig meat makes you ill because of the dirt). * The relation of the animal to the human. Farm animals are likely to signify luck or wealth. Animals that are a thread to humans, to farm animals or to food supply are likely to be associated with evil traits. * Special features, and the way those get explained. For example, the Dalmatian pelican gets a red spot on the throat during breeding season, which gave rise to the myth that pelicans feed their young with their own blood if no other food is available, which affected the symbolism of the pelican as especially caring for the young, and as symbol for the passion of Christ. * Association with other symbols (animal or otherwise) for the same thing. For example rabbits are commonly associated with fertility, for obvious reasons. Similarly eggs are associated with fertility. The association of both with fertility (and thus with spring and then specifically Easter), led to associating them with each other, and ultimately to the myth of the rabbit bringing the Easter eggs. * Distinction of the own culture/religion from other religions/mythologies. For example, the cat (a very useful animal that catches rats and mice, and therefore protects from food loss and illnesses) was seen as very positive by the ancient religions, and that was the reason why Christianity associated them with the devil. Indeed, I've once heard somewhere that the fight against cats was one of the reasons why the pest could get out of control. Also the fact that the snake in the bible is evil might be a reaction of the snake being considered a positive animal by the surrounding religions. [Answer] The most important prerequisite is that the animal in question has to be native to the region the people live in. You wouldn't expect, for example, people living around the equator to have myths involving polar bears. Next, it usually has a profound impact on the society. Animals can serve as food, so they might be the avatars of the god of fertility, or even the creator of all living beings. Animals can be predators, maybe even pose a threat to humans, so they might be representative of a vengeful god, a god of war, a destroyer of worlds. They might just be an accidental threat, like scorpions, representing Death and the underworld. The physical abilities of the animal also influence the properties attributed to it, by process of anthropomorphization. How an animal is viewed can also depend on the type of society. While a pig could represent fertility and benevolence of the gods to people in a hunter/gatherer society, it might be a symbol of fortune and wealth in an agricultural society, and a low, dirty animal (tended to by low, dirty humans) in an urban society. As for practical advice: Don't be ashamed, read up on animal myths as they exist(ed) on Earth, and draw inspiration from there. Better use a good copy than a bad original. [Answer] Many totemic animals are selected because they have qualities which we wish to emulate, or to signify some of our powers to potential mates or foes. This is why the garden slug is not often evoked as a totemic creature or the symbol of a cult figure or a god. Now if garden slugs were the size of semi trailers, there might be a change in attitude.... Since as far as we can tell, early cultures tended to live in a very spiritual and "living" landscape (each individual tree or rock might have a spirit), early people were on the lookout for signs that would explain the day to day world around them. Some objects, like rocks and water, might have visible manifestations but show very little activity or change over the course of a season, so have very "limited spirits". The river god periodically flexes his muscles and floods the land, but then goes to sleep for the summer. Totemic animals would be the ones which could provide a range of fascinating activities to the observant hunter gatherer or early farmer, and these actions would then be "mapped" onto the mental picture of the universe. Gifted story tellers could take these observations and "mappings" to explain the wider world in ways that people would understand (i.e. while the river god is sleeping, the crows are flying into the fields to steal his grain). Obviously the more "primitive" the world view and the more that things are explained by animating spirits, the more elaborate and disconnected from "reality" some of thee myths could become. As societies became more "rational" and people observed there were actual causes and effects (and needed less of a spiritual explanation to how things worked), then the meaning of animals would become more "literal". The ancient Romans observed the Eagle was a powerful predator and associated it with the god Jupiter. Americans, living in the Age of Enlightenment, could still take the Eagle as a symbol of power as a predator, without necessarily evoking a deity to explain it. Modern sports teams still do this sort of thing today (The Toronto "*Raptors*", or the Denver "*Broncos*", for example). So depending on the "time" of your story setting, the people can be using the animal as a symbol for a spiritual being to explain how the world works or evoke the animal for qualities that the people would like to emulate. [Answer] An interesting one in Australia is the Rainbow Serpent responsible for creating much of the landscape. When you fly over Australia - or I presume stand on a high hill or mountain you can see in the land below great crescent shaped marks filled with water that are just like the marks some snakes make when they "shoulder" their way across sand. Now the geology is that these marks are made when rivers and streams change course and the deeper pools at the bends where the water ran faster remain long after the river moved on. But from an Aboriginal perspective it makes a great story to imagine a huge snake - the rainbow serpent - moving across the land and making the features of the landscape. So to answer your question in your landscape you have features - rivers, rock formations, mountains whose shape is similar in some way to an animal or the marks that an animal makes and build a story around this. Perhaps winds through a cave system sounds just like the roar of a lion and evolve a myth that a mighty lion died in the cave and his spirit lives there to this day. The thing is that when people see the landscape they must see the "truth" of the tale. They can see the marks of the serpent, they can see the jumble of rocks where the giants had their battle, they can hear the roar of the lion. [Answer] The question has two parts, which I will address separately. # What process can we use to create animal meanings? Most myths and legends begin, when a group of people are sitting around campfire, in a cave, or in a hut... Outside Mother Nature unleashes her fury, by sending torrents of rain and casting roaring thunders. Wind slams against the walls, yet in the middle of the darkness you think that you saw something. A movement maybe? Or was it a pair of eyes, full of hunger and hate? Before you can ask the guy next to you if he saw the same thing, the oldest man in the room, an experienced hunter and brave warrior, begins his tale... > > Have I ever told you, how I lost my middle finger? No? Well then, you see, wolves have a very peculiar habit... > > > If you want to create a good myth, imagine yourself sitting in such hut, hungry and thirsty, listening to old man, looking at his scarred face, while he tries to scare the shit out of you and comfort you at the same time. And now fast-forward 50 years. You are now the elder, perhaps you are missing a limb or an eye. All eyes are fixed on you, waiting impatiently for words of of wisdom. You take a deep breath, take a sip from your cup and start retelling the same story you've heard so long ago in a lonely hut. Sometimes you omit something, sometime you add something from yourself, but one way of the other it's still the same story about peculiar habit of the wolves. If you want to create myths, put yourself in this mindset, and you shall not err. # What leads cultures to choose specific animals for specific meanings? One way or the other - fear. Fear comes in different shapes and forms. Some are afraid, that they will meet a giant bear, while hiking in the woods. So they build little shrines, so the spirits of the forest will divert the bear from their path. Others know how to use that fear - they dress up as bears to strike destroy courage of their enemies, or they hunt for the huge animals to gain respect of their tribe. Bears are fearsome, because they are big, strong and hard to kill, and those qualities are recognized in bear-related myths. Some are afraid, that a pack of wolves will attack their cattle, and they will watch helplessly, as their food supply is destroyed before they very eyes. So they build little shrines, to divert wolves to the next valley. Others know, how to use that fear - they mimic a pack of wolves while attacking an enemy, to make an impression of one, perfectly coordinated killing machine. Wolves are fearsome, because they are excellent trackers, they have strong jaws and sharp claws, and they can work as a team. Those qualities are recognized in wolf-related myths. Some are afraid, that a fox will sneak into their farm and kill all the chickens and they will starve. So they fortify their henhouses hoping to stop the animal. Foxes are fearsome, because they are smart and agile. Those qualities are recognized in fox-related myths. Some are afraid, that their cattle will fall victim to a disease and die, or that they will not reproduce. Some are afraid, that rats will infest their pantry. Some are afraid, that a certain species of bird will not make its nest on the roof, which is a sign of bad luck. We can go on like this forever, but I think you get the idea. Think of an animal, connect some sort of fear to it and turn it into a story. ]
[Question] [ So imagine any typical post-apocalyptic world, recently cast into their misfortune. A very large percentage of humanity has been killed, leaving a very large stock of property to be looted. I suspect that food and fresh water are the very first trade goods than anyone would care about. But as time progressed and more and more grocery stores and things are looted of their wheaties, I would think that those who survived that long are able to get their own food and water often enough, so I wonder what kind of non-perishable, irreplaceable goods would become trade commodities, or at least commonly traded. Some ideas: * candy - people have a sweet tooth. * peanut butter - Don't need a reason. It's peanut butter. * canned goods - Lasts forever and sometimes contains foods that would not easily produced for many decades. * spices - perhaps a new luxury item because many spices only grow in certain parts of the world. As these limited goods would be used up, what would replace them? How might their value increase or decrease over time (e.g. a candy bar used to get you a gallon of water, now it gets you ten). I have intentionally focused on edible goods. Naturally, people trading water for a candy bar probably intend to eat the candy bar, thereby reducing the remaining supply. My question is about the economics of these kinds of things and what kinds of non-perishable, irreplaceable food items would be most valuable at first and how that would change over the next decade or two after the apocalypse. [Answer] ***Quality alcohol*** is probably one of the most important commodities you'd find in a post-apocalyptic barter economy. Why? 1. Without large-scale water filtration systems in place, it's safer than water. 2. It's difficult but not impossible to manufacture. Specialized equipment for malting, fermenting, distillation, etc. can be hard to come by. These might be even more important tools due to their function as capital to produce a valued good. 3. Well packaged alcohol can last quite a while in a natural environment (use caves as cellars, etc.) So groups of people can control market supply more effectively (if there's a glut of beer, wait until it dries up to offer yours.) 4. It works as a sterilizer in a pinch. Important when antibiotics aren't readily available and your autoclave is broken... :) 5. At the end of the world, EVERYONE is going to want a stiff drink. Depending on how you're looking at it, ***labor supply*** is a vital "good" in a society that needs to revert back to small scale agriculture. Basically, you'd have tribes of people who are either slaves/indentured to a local power, or have banded together as a "temp" service for communal profit - a large extended family hiring out three teenagers for the harvest season for a share of the harvest and some extra trade goods, for example. ***Livestock*** may be even more important than labor itself, combining both a food source and a labor source in one. In all likelyhood, large-scale raising of cattle will require too much food to be practical. Instead, there would be "the family cow/horse/donkey/etc." and shepherds with ***flocks of goats***, which are hardier and can be grazed on more unfriendly terrain. Some [interesting details](http://www.lohmann-information.com/content/l_i_45_artikel17.pdf): > > Goats can withstand heat stress and can endure prolonged water deprivation. They have additionally great adaptability to adverse climatic and geophysical conditions, where cattle and shee cannot survive. [...] Dairy goat is considered the cow of the poor. The goat eats little, occupies a small area and produces enough milk for the average unitary family, whereas maintaining a cow at home cannot be afforded by the homeowner, hence, the growing popularity of goat as the poor person’s cow. > > > In more northern climes, ***domestic sheep*** will be as common (or more common) than goats, especially for their wool production. Expect to eat a lot of [feta cheese](http://en.wikipedia.org/wiki/Feta). Depending on how "Mad Max" we're getting, ***bullets*** will retain their value if hunting or defense becomes necessary. Glass tends to be too fragile to depend on when there's no police force keeping vandals and burglars from breaking windows. ***Plexiglass*** and other clear plastics become very attractive options for windows. ***Honey*** is a good alternative for sugar that's not very "work intensive" but fulfills the public sweet tooth. Expect dried/baked honey as treats in the long term, with an established beehive being a MAJOR money maker both as a producer and a pollinator. ***Salted, brined, and dried Goods*** like fish, meat, and certain vegetables would replace our canned goods when we run out - they last a good while and can be produced in your home with little special equipment. That being said: ***Salt*** would become incredibly economically important again for these purposes. We currently extract salt in large factories and mines (yes, even your hoity-toity Pink Himalayan salt and Black Hawaiian salts.) When those shut down, you'd be digging by hand (unlikely) or using the age-old method of evaporating it out of the sea water. Setting up large plexiglass evaporators will help distill both salt and water - a double win. This will require a decent bit of land to accomplish at a worthwhile scale, though. ***In terms of the economics,*** we would see broad hoarding at the start with overinflated prices vis a vis supply with large fluctuations. When the market calms down (and populations stabilize,) we'd see a return to rationality with relatively stable rates depending on production - lower for grains and farmed goods, higher for complicated, hard to replace goods like durable metal objects, quality clothes, and refined foods like candy (twinkies?). Within about a week, most produce will have gone bad. Without the shipping infrastructure, getting ***fresh fruits*** out of season will be nearly impossible. In old still life paintings, the presence of fresh fruit, and especially oranges, was a distinct sign of wealth. There is ancient literature that describes people's wealth by stating that they had winter fruits in the summer and summer fruits in the winter. Locally produced fruits will be cheap at the point of production but very valuable as trade goods in a caravan outside of normal growing ranges and seasons. Expect more dried fruits for preservation, especially for berries, cherries, and the like. Melons don't really preserve though (and require lots of water), so serving watermelon, canteloupe, honeydew, etc. will be a strong display of wealth. Things like peanuts will be valued for their high nutrient content and long storage life (as will all legumes in general), so they will be valuable, but probably reserved for special or extreme occasions (either a celebration or a food shortage) which will keep their price in check - people won't consume them as quickly as other, more perishable produce. ***In the long run,*** we'd probably start substituting a more readily available good for the latter category - like the aforementioned honey for candy, wooden items for metal, rough woven cloth for manufactured cotton, etc. Eventually, it will be so commonplace that using a metal spoon will seem strange to the average individual. Only "collectors" will be interested in these special items, and will probably be willing to pay a premium for people able to find "vintage" relics of the "earth that was." PS: dried grains wouldn't get "used up" - you always preserve enough of your harvest for AT LEAST one year of sowing, preferably two (in case one crop fails.) ### Economic Timeline: **Week 1**: panic. massive looting, little real economic activity. Formation of raiding/looting groups. **Week 2**: most unprocessed food starts to spoil. Panic driven trading and inflation. Groups will start to merge/compete/disband/fight. Some will probably start to engage in long term planning, such as creating mutual defense pacts and farming/trading collectives. **Month 2**: people start to settle down from panic and focus on short term survival. Durable goods, seeds dominate trading. **Months 3-6**: depending on the season, people focus on purchasing livestock for animal labor and interim food supplies while crops grow. Travelling labor collectives and small towns form. **Month 12**: People coming to grips with a year of post apocalyptic living. Longer term planning starts to come into effect. People focus on making tools. Metalworking repair skills will become very valuable to keep equiment functioning. New metal will be harder to come by. People began to craft rough metal and wooden tools as replacements. Medical supplies become scarce, people start dying from basic bacterial infections. People start substituting beer for suspect water. Evaporators set up to provide for fresh water and tradeable salt. **Years 2-3**: Expect to see the first batches of distilled alcohol, low percentages, not well aged. Also expect to see methanol poisoning. Possible establishment of some sort of currency - either grain, peanuts, or workable metals. **Years 4-10**: Food prices stabilize locally based upon available producers and inter-regional trade. Non-seasonal fruit recognized as a status symbol. Very few pre-apocalyptic durable consumables remain. People shift consumption to renewable goods. Assuming that they aren't burnt for warmth, books are valuable sources of knowledge and entertainment. Many modern books will decay due to exposure (your paperback is made of VERY cheap paper). **Second decade**: Children of the apocalypse come of age. Raised without cultural trappings, they will find plasticware and metal utensils strange. Wealthy older people become collectors willing to pay money for rare items. **Third decade**: The start of larger governments, either warlords or something resembling the Senate of old. Stability means people start to recreate old knowledge of medicine, science, and technology, trying to preserve what they remember before it becomes irretrievably lost once the next generation takes over. [Answer] I agree with Isaac's answer but feel that he left off a few points, besides the obvious toiletry items of condoms, tampons, and toilet paper being valuable trade goods in the first months and years, as follows: Spices are completely the thing that is going to be valuable that everyone is probably going to overlook, until they don't realize how valuable they are. The spice trade is still today a world spanning global market and was something that in the past made cities and empires rich. There are today still spices that are worth more than their weight in precious metal; not that those need to be focused on in an end of the world setting where the global supply chain has collapsed. The interesting thing about spices is that having a good supply that lasts for some time actually isn't that heavy, but it makes a huge difference in eating. Seeds, especially seeds that lead to food, and then seeds that lead to spices are going to be sky high valuable, for a while. Some spices you just have to have a hoard of, others though can be grown if you have the know how and the seeds to do so, and the stability and have survived to the point that you can expend the energy on growing spices. It is a risky move keeping alive gardens and possibly cobbled together greenhouses of things that primarily provide flavorings over substance, but there could be a pay off. Candy would certainly gain value as time went on; all that processed sugar and memories of a better time and life, for a while sure it would a survival item but then any candy left would be much more than that. [Answer] Tools, tools, tools. The problem with trading food is that it's perishable, and also there isn't much point in trading it because if you are scavenging everyone has pretty much an equal chance of turning this up. There is thus no comparative advantage to motivate trade. Are you really going to go a great distance and risk interacting with people to swap your peanut butter for candy? Is this really going to be a thing you do over and over again? If I have an extra can of beans, why should I let you have it, when I can just keep it and feed myself with it some day? What sort of mutually beneficial arrangement can we possibly make? So you really want tradable things that any one person can easily be in surplus of, where one person or location might turn up more than another location, that cannot be easily substituted for other items, and whose supply is very limited. I think if you look back to early civilisation, you'll see that the key trade product is tools. Even something like a screwdriver would be huge. A saw to cut down trees with? Can openers? Wires? Nails? Pencils? Ploughs? Spades? All of this stuff are treasure troves any person can turn up lots of, that are highly useful, that another person might not find any of, and that can not be replaced until humanity returns to the industrial age. [Answer] Focusing solely on the consumable end of the post-apocolyptic economy, a trader would want to offer those food items that have legendary healing or disease prevention attributes. Most people know that citris fruits help to prevent scurvy. They probably don't know what scurvy is, but they know that they need oranges to avoid it. An Apple a day is a great sales pitch. Spinach makes you strong while canned-oysters and chocolate improve your love life. The lore and mystic of these consumables might enhance their trade value, giving the trader a higher weight-to-trading-value ratio than other room-temperature consumables. [Answer] Variation on the "tools" theme: tools and techniques for preserving food. You may be able to raise pigs, but if I have a smoke house and salt for curing meat, then you have a reason to deal with me (it may be much easier to get customers for a side of bacon than a live pig, depending on where you are and what your customer wants to do). Canning, smoking, curing, preserving, making jams and jellies will all be valuable skills and the equipment needed to do these things will also have a great deal of value. For people who are not living the neolithic hunter gatherer existence, having food items which are somewhat portable and long lasting will also be valuable, and worth giving a small "cut" of the raw or fresh foodstuffs to the food processors in exchange for having the rest of the food turned into high value added products. As an added advantage, a food processor will have some value to the "Lord Humongus" in a Mad Max scenario. You don't want to kill the only guy who makes bacon, and he might not be able to move around very effectively ("Hey, Humongus. If I have to leave here I won't be able to smoke the bacon with this special hickory wood. You wouldn't want your followers to start having to eat sub standard bacon, would you?"). Less likely to be killed or pillaged, which is always a consideration after the Apocalypse. [Answer] I loved Isaacs answer, I just wanted to add one thing: **Cow's milk.** Dairy farming has been part of our history for thousands of years and dairy products are an important part of our diet. There is also a bit of an emotional/cultural attachment to milk. We give it to our children when they are young to help them grow big and strong. I have fond memories of being a child and sitting down with a big glass of cold milk and a cookie. My dad tells story's about drinking the milk fresh from the cow, with the cream on top. Depending on how much of the human population has died, there is a good chance all, or most, of the dairy cows would be dead within about a week. They just can't survive without human assistance. Even if some of the stock is saved, distribution and supply will be cut off for a really long time. So long life milk will be huge currency during the first few years, and anyone who manages to get into dairy farming will do very well from themselves. I also think Spam and Chicken in a can will be super valuable. Salty long lasting protein, enough said. [Answer] Since the OQ specified **trade** goods, I think that implies a recovery from absolute chaos, such that people are trading/bartering instead of literally cannibalizing. In this case, I assert that: * Coffee, * Cocoa, * Tea Will be highly desirable, valuable trade goods. Just imagine waving a cup of coffee near a caffeine-deprived former Starbucks aficionado in a trading situation; ka-ching! **Edible oils (soy, canola, peanut) are another possibility**, they're calorie dense, have long shelf lives -- and can be burned for light (if no electricity.) Points for those who have mentioned seeds, spices and tools (though the tools themselves aren't exactly food.) ]
[Question] [ For context, there is a planet that is kept isolated from the larger civilization of star systems it should be connected with—in terms of communication. A base population is already present on the planet. On the remaining celestial bodies of this star system are a third party’s personnel, transport, etc. Warp tech is present so that the whole atmospheric re-entry and exit can be skipped, but it and other such advanced tech is only accessible by the third party. This third party wants to keep the aforementioned planet isolated for the main purpose of extracting humans to do specific labor. I want this planet’s populous to be unaware of the larger context around them without breaking worldbuilding through said planet advancing too far, discovering the third party that limits them, etc. Is it possible for an entire planet be exploited without its inhabitants knowing it’s being exploited? Can the planet be kept both isolated and technologically stagnant enough so that this operation isn’t interrupted or ruined? Edit: Thanks for the replies, they’ve been really helpful in figuring this out! Just want to pin down a couple more points. To do that, I’ll clarify the aforementioned “labor.” The peoples taken from this exploited planet would participate in something like the Abbasid’s “ghilman,” but adjusted to swap literal slavery for wage slavery. Does this setup necessitate that the exploited planet’s people are (as per @L.Dutch) at “barely subsistence level?” Does that mean their society is something akin to dark ages Europe or remote regions of Africa? Given the most voted-upon answer as of writing this, I’m thinking of making the planet largely dependent on primary economic activity, with little secondary, and fewer tertiary activity. Would this best suit the exploitation system described in my original question, or is there a higher threshold of development that would allow the system to function at maximum effectiveness? [Answer] It's possible, and I think it has happened with some countries/populations in our history: didn't somebody trade glass beads for valuable exotic items? Technology and knowledge need to start somewhere to spread, if you prevent the spark to happen, you will not have to worry about fire spreading. And it helps keeping the innovation low if you can control the society and the standard of life be at barely subsistence level: like the Romans said "primum vivere, deinde philosophari", first worry about living, then about making philosophy. If you are too busy worrying about reaching the end of the day alive, you will have less time to investigate advancements of any sort. This will result in your society being stagnant. [Answer] **Tunnel world** They never see the sky. They do not know about the sun and the stars. If a tunnel breaks through to the surface that is worse than a deep tunnel breaking thru into lava - water pours down into the tunnels. They need to be careful about digging too high. They do not know they are on a planet. The concept of "planet" would be a struggle for them. Tunnels also make it easy to harvest the humans. [Answer] #### Welcome to Paradise\* You are worthy. You are valued. You will work for your kin, and they will work for you. Anything worth having is provided by the Powers that Be, to whom the best and brightest may ascend. Praise be unto their unknowable wishes. (Hope that the destruction from their displeasure doesn't happen near here.) --- #### No need for a low standard of living ... just low opportunity to tinker. All production is handled by black-boxes, and nobody knows how to operate more than one. You provide the black boxes. Therefore anything someone makes is either inferior to what you provide, or you know which drone to harvest next. If you have sufficiently advanced technology (relative to them), you can educate your population to consider it good that you're watching invisbly, and send in a drone with a spotlight to mark someone as favoured. They will visit the temple to ascend (with a celebration) and you now have a willing labourer with unusually high tech-skills. You tell this volunteer that their efforts help to maintain Paradise for those at home. Just in case, you discourage travel (and nuke-from-orbit anyone who tries) and apply tracking implants liberally. Also possible is inhibiting vitamin production and then providing salt-licks in the town square, just in case. There is no need for trade. Dissenters can be excised without anyone knowing why, and so "heresy" cannot spread. They'll also lynch any outsiders who land, if you tell them to; and hand in any gadgets which they find (and can't recharge anyway). --- As for not being discovered, it's easy to hide (lots of planets exist) unless someone traces your supply-chain. Of volunteers. Who exactly is unhappy with this situation? Will your labourers eagerly testify that they'd prefer that their home remains the same, and beg for it to be declared an ecological preserve under [controlling organisation]'s stewardship? It doesn't have to be a planet, artificial structures don't have to exist in a natural orbit and are therefore harder to detect accidentally. [Answer] A leaflet from the establishing and maintaining a cult manual - institutionalized religion with complicated rituals and a strong emphasis on community living and conformity/traditions. Strengths: * suppression of individuality - to the point in which even the idea of monogamous relations and small/individual family is non-existent * maintaining a division of labor that can support the community in spite of their best members being 'harvested' * reduced cost of dissent surveillance - they'll do it to themselves * dial in the level of well-being and heath that you need your laborers to be at the moment of harvesting them Weaknesses - *that will need to be addressed* (not necessary fatal) * hard (but not impossible) to justify the 'harvesting of laborers' - will it be a reward or will it be a punishment? I mean, one needs strong and compliant humans as workers, so you'll need to promote such values. But then it will be hard to socially justify 'harvesting' those that are probably also the best the community can have. Additional material to draw inspiration from - the [list of new religious movements](https://en.wikipedia.org/wiki/List_of_new_religious_movements) - pick the ones that popped-up relatively recent (in the '60-'70-ies as the earliest). [Answer] # Encourage widespread virtual reality retreat. Using brain implants, which are a twenty years in the future from today technology thing, you could have people spend most of their time in virtual realities, living on welfare. # Make society shitty. This could be encouraged by ensuring that their society was unpleasant for most who stayed out, with lots of racial, political, gender and religious strife encouraged by their propaganda machines. Being able to control social media and generally use superior technology to hack most computers helps with this. Most people could retreat to virtual reality worlds, to escape continual cruelty on social media and in real life, and constant bitter fights that the third party inspired. Any who they wished to recruit could be trained with targeted advertisements to such virtual reality worlds to invite them into training games, or encouraged to return to real life and granted power and prestige. [Answer] Two possible scenarios: ## The local rulers are in on it. Yes. With the help of the rulers just about any level of deception is possible. There is no space research because "everybody knows" space is too expensive, it will never give a return on investment. You *can* fool all the people all the time. Still, there will be a number of people who will know the truth and somebody just *might* say the wrong thing where the wrong ears can hear. ## The local rulers don't have a clue. Much harder. I would still call it possible. The third party will need to have secret agents in place to keep things in order. You can still make most people believe space is not worth it, though there will always weirdos who try. The secret agents will need to "discourage" the wrong kind of research. There will be a limit to how much exploitation you can do before the local rulers catches on. [Answer] I feel obligate to mention Safehold series by Weber here. Religion is the driving force behind stagnation there. A religion that was specifically designed to stagnate everything. **Successful?** Safehold is a society that is held in stagnation for about 900 years on a planet in the middle of nowhere. There is at least one other society 'around' (quite far away tbh), but it never finds them. Thus, an isolated and stagnated world. **Longer Explanation of Safehold:** **Exposition:** Humanity lost a war against aliens (the aliens have vastly better technology), flees into the far reaches of space. Humanities last colony decides the only way of surviving is to make sure that the colony never reaches the point where they emit any detectable signal (or alter planet atmosphere in a recognizable way) from space. **Religion** People are taught the *prescriptions* written expectations of what is allowed and disallowed. Everything that is against the prescriptions is punished by the order of Schueler (think inquisition). Part of the prescriptions is just simple things like nutrition where the "punishment" is scurvy. **Implementation** Colonists have memory wiped. The writings are attributed to the "angels" (old Earth military who mascaraed as Angels for a while). The military (angels) guide the first few generations. Then they "leave" for heaven. The "angels" built "religious miracles" like a temple with climate control etc. The culture is strongly against change as it might eventually go against prescriptions. Science is nearly non-existent as all needed science was given to the colonists by "angels". Mathematics is bound to roman numerals...... So no real sense of math exists (multiplication is hard, everything else is impossible to compute with numerals). Society has enough to build sail ships (think Pirates of the Caribbean), but nothing else. Also, the book notes the obvious flaws that should have been excluded (the story is about changing the society, so the flaws were needed). **Pertaining to the question** Safehold is a crafted example of specifically designing a society and world where innovation is seen as evil based on religion. With the right building steps, your world could be similar. Have the "angels" group not die off and everything would work out similarly. Or, as needed have the divine "writs and prescriptions" change to fit your specific needs. The most important take aways are avoiding the need for innovation, limiting science/math capabilities, and making life hard (labor intensive work around the planet leads to less free time to think). [Answer] **Out of sight out of mind** If the system was in the middle of nowhere (other nearby systems are uninhabited or its dangerous to pass through the space around the system), then its less likely you'll get visitors from other systems wondering where all this human labor is coming from. This means its much less likely the inhabitants will ever find out that other beings exist. The third party could also spreads lies like all the people on the planet are cannibals, its always raining, and they ran out of coffee. Thus no on will want to visit the planet even if they where willing to risk the journey to the solar system. **No one wants any technology** The third body then just needs to install itself as the religious leaders and declare technology to be the work of the space-devil and thus no one should ever think about making any kind of technology. Anyone found with something more advanced than a wheel shall we put to death, lest they bring the wrath of the space-devil upon the local population. [Answer] The Old Man's War trilogy by Scalzi does something like this. Earth is kept isolated from the universe, so they can be farmed for colonists or soldiers. [Answer] **Fill the planet orbit with debris to physically isolate the planet.** The third party could fill the planet atmosphere with space debris/asteroids to prevent any ship or communication from leaving. So even if the the local populace have some level of scientific and technological advancement, they can't leave without warp tech or something to protect you from the debris (i.e : shield system) The debris/asteroids could often shower the planet, making it harder to form a stable civilisations and slowing down progress. Harvest could also be perfectly explained by the locals as just another villages, cities, tribes being whip out by an asteroid (Just leave a big crater once you finished harvesting your future workforce). [Answer] I agree with other users that keeping people at barely subsistence level is effective. But another reason why Africa never developed even though it is the birthplace of our species lies in the widespread tropical diseases. They kept the population density low thus limiting the communication between tribes and the cultural development. If you need a big source of human labour rather than a planet you might have a system with several small planets in the habitable zone each capable to support a small population. If each planet also contains zones separated by impassable mountains or toxic seas to limit the communications and cultural exchanges it would be even more effective. The speed of the development in high density areas like China compared to isolated areas like Australia is enormous. Another effective design would be a planet where for some reasons there are only barren deserts or dense jungles. Thus the population would be forced to live in areas where the communication is limited and develop slowly like the tribes in the Amazon. However you cannot completely stop cultural evolution in this way, but there is last trick. > > This third party wants to keep the aforementioned planet isolated for the main purpose of extracting humans to do specific labor. > > > If this third party kept secretly observing the population they could simply take away the brightest for the work they need. [Answer] Use a long term aerosol that creates a permanent cloud layer over the planet. The sun is a sullen glow through the haze. No stars are visible. The spaceport is surrounded by a killing field. It would be sufficient to have a band of highly radioactive land around it. Come and go from the port by a 20 mile long tunnel. The land around is inhospitiabl enough that no one normally would travel there. As examples, consider if it was located in the Empty Quarter in Arabia, or on a small island mid Pacific, or north of treeline in the Canadian archipelego. From the space port, 3rd party do their recruiting based on local transport. (Sailboat, steamship?) You need to decide what level of tech to keep them at. E.g. if they start developing aircraft, you have local agents that ensure that aircraft have frequent enough failures that they are uneconomical. [Answer] All you have to do is convince the inhabitants that the speed of light is only 300,000 km/sec (186,000 miles/sec), and that nothing can propagate among the stars faster than light. They will not develop much interest in interstellar journeys that take longer than a single individual's lifetime. A simple local superluminal-denial field generator hidden somewhere in the system's Oort cloud will usually do the trick. You can often pick up one of these for a song on g-Bay (except on Kura-Khalifa where singing is illegal). An extremely convenient technique, although not strictly necessary, is the introduction of a "UFO cult": a popularized conspiracy theory that holds that aliens regularly visit or are secretly resident on the planet. You have to gen this up as a bunch of nuts whose faith never wavers but whose evidence somehow evaporates under serious examination. If anyone stumbles on the truth, the other inhabitants will instantly assign him to this cult and disregard his evidence. He can then be removed or neutralized at your convenience without raising too much of a fuss. Earth (Sol III) has been sequestered this way for millenia. ]
[Question] [ Edit: I am asking in the context of alien life, should have specifyed that to begin with. I have many ideas for fantasy/sci fi races, and one that I kept coming back to is a species with bones that are based on an element other than calcium. Is this possible and what would a good element be? [Answer] Bones are really fantastic, from an engineering point of view. We intensively use them for 80+ years with practically no big issues and they can even self repair, while whatever thing we engineer design is prone fatigue and wear. This awesomeness doesn't come from the particular element which is used to make them, but from the peculiar way in which they are made: instead of being built once and forever, like we do with any metal beam, they are constantly demolished and reconstructed by the body cells (osteoblasts and osteoclasts), so that, effectively, your bones today are not the same bones you had one year ago. This means that fatigue like we know in metallic alloys is less of a concern, as any microscopic damage is wiped out by this process. And by using this process we also see how the bones can self repair! And you thought that painting the Tour Eiffel or the Bay Bridge is San Francisco was a hell of a job! You ask which other metal can be used to replace Calcium. In principle, any other element in the group 2 of periodic table, which contains * Beryllium, * Magnesium, * Strontium, * Barium, * Radium could show similar chemical properties. However calcium is the [fifth most abundant element in the Earth's crust](https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements), the other being * oxygen 46%, * silicon 28%, * aluminum 8.2%, * iron 5.6%, * calcium 4.2%, * sodium 2.5%, * magnesium 2.4%, * potassium 2.0%, * titanium 0.61% Keep in mind that calcium is also [widely used in our body](https://en.wikipedia.org/wiki/Calcium): > > The $Ca^{2+}$ ion acts as an electrolyte and is vital to the health of the muscular, circulatory, and digestive systems; is indispensable to the building of bone; and supports synthesis and function of blood cells. For example, it regulates the contraction of muscles, nerve conduction, and the clotting of blood. As a result, intra- and extracellular calcium levels are tightly regulated by the body. Calcium can play this role because the $Ca^{2+}$ ion forms stable coordination complexes with many organic compounds, especially proteins; it also forms compounds with a wide range of solubilities, enabling the formation of the skeleton. > > > Therefore, your closest replacement might be magnesium, based on its electronic configuration and abundance in Earth crust. But keep in mind that if you replace calcium with magnesium you also need to redesign all the system using calcium in our bodies! [Answer] **Silicon, as silica (SiO2).** Behold: the skeleton of the glass sponge. [![enter image description here](https://i.stack.imgur.com/CeWNA.jpg)](https://i.stack.imgur.com/CeWNA.jpg) <https://www.atlasobscura.com/articles/sponge-record-climate-change-data> > > Glass sponges in the class Hexactinellida are animals commonly found > in the deep ocean. Their tissues contain glass-like structural > particles, called spicules, that are made of silica (hence their > name). Some species of glass sponges produce extremely large spicules > that fuse together in beautiful patterns to form a “glass house”—a > complex skeleton that often remains intact even after the sponge > itself dies. > > > <https://oceanservice.noaa.gov/facts/glass-sponge.html> Silica is widely available on earth and is used by some animals to build skeletons / shells in the way most animals use calcium. The glass sponges are one example; radiolarian protists are another. As with "woven bone" it is not the mineral itself but the structure in which is laid down that confers the strength. The glass sponges must be able to repair their silica skeletons. These animals get big, and very old. [Answer] Found something that may work. Chitin, (C8H13O5N)n. If you can make an endoskeleton of it, its not based on Calcium. [Answer] **Why not carbon?** Carbon can form diamonds, carbon nanotubes stronger than steel and graphene sheets flexible as plastic but tougher than bulletproof glass. A carbon based bone structure could use properties from all three forms to have bones that are virtually unbreakable. Considered we are already a carbon based lifeform, carbon seems the obvious choice. [Answer] This isn't quite a direct answer as it's not replacing calcium in bones, but there are a few options for stronger biological materials. * [Limpet teeth](https://www.australiangeographic.com.au/news/2015/02/sea-snail-shell-the-worlds-strongest-material/) use fibres of goethite which form 'the strongest' biological material known to man. Unfortunately, from my search I haven't yet found what constitutes 'strongest' in this instance. They're compared to spider silk which implies tensile strength, but I could well be reading into journalistic licence. For a substance to make good bones it needs good compressive and reasonable tensile strength. They're also described as 'hard', but hard substances can still have poor tensile or compressive strength. However, a benefit * [Abalone shells](https://www.news.ucsb.edu/1999/011245/nature-publishes-secret-abalone-shell-strength) use a composite structure of calcium carbonate crystals and rubber-like flexible proteins. This gives them phenomenal shock resistance, and also reasonable compressive and tensile strength. This may be a very good option. * [Scaly-foot snails](http://news.mit.edu/2010/snail-shell) use shells that have a 3-layered composite structure with an outer layer that includes iron sulphides, a flexible mid-layer, and a calcified inner layer. This makes them very hard, very resistant to crushing forces and very good at dissipating shock. ]
[Question] [ In the near future (next few decades) a giant spaceship is detected as it decelerates on its way into the solar system. It heads for Earth orbit, but a few weeks before reaching Earth, it veers away and ends up in orbit around the sun not far from Earth, about 10 times the Earth-Moon distance. The ship doesn't respond in any way to attempted communications. NASA re-purposes a satellite that was scheduled to launch for Mars and approaches the ship. To everyone's surprise, the ship opens a large hangar door and sends some radio signals to the satellite. After some time and repeated signals, the door closes again. Next an international team goes and boards the ship. It turns out to be a generation ship but evidently failed, as it's full of dead human-size insectoids and only a few cryogenically frozen specimens, most also dead. The ship seems to be otherwise intact and is run by some kind of computer. Unfortunately, the computer is not compatible in anyway with Macs or any other human-made computers. With some advanced cameras, the displays can be converted to human vision and they appear to show that Earth has been rejected as a colony world and the next destination is an Earth-like planet most likely some 50 light-years away. There's also a countdown of uncertain length, but likely to be 3-4 months because that will be when the trajectory towards the next star is optimal. Some humans decide they want to grab this once in a lifetime chance to hitch a ride on this ship, despite the risk of meeting the same fate as the original crew. ## The technical part The aliens' basic physiology is compatible with Earth-life (the very reason they headed for Earth) and the atmosphere on the ship is readily breathable by humans. The water dispensed in the ship has way too high mineral content, but nothing that would destroy human filters and some specific taps supply demineralised water. However, the plants in the hydroponic farms are all toxic to humans and while the light seems good, the water is full of bacteria that kill any other plants. They need to be flushed and run manually somehow. The waste-recycling method is unknown (it can be adapted to make things more workable). The ship itself is designed in a very distributed and resilient way. Attempts to remove subsystems and attach human systems to their power supply points work once it's figured out the ship supplies DC electricity at the roughly the voltage indicated by the system upon connection. Unfortunately, no control connection seems to work, nor does the ship's computer interact with the systems in any way. The computer running the ship seems to have been programmed in a very permissive way. It doesn't take any hostile action and doesn't override or reverse non-damaging changes to the ship. It appears to recognize humans as living and treats them as if they were regular occupants, activating lights, heating and other functions on demand. It even responds to certain sounds, but the reply is always the same, most likely "I don't understand your request, try again". However, it doesn't recognize anyone or anything as having the authority to access or change the reactor and drive section nor the navigational systems. The same goes for the shuttles and landing craft in the hangars. The ship is going to depart and short of destroying it nothing will delay that. Humanity has one huge leg up: They have established a small base on Mars and were just preparing a serious colony mission consisting of 2 passenger ships holding 50 people each and several cargo ships to deliver machinery and supplies enough to set up a colony for those 100 people. The alien ship is much closer, so multiple trips per ship are possible. The sponsoring governments are loathe to postpone the Mars effort, but if the chances for surviving on the alien generation ship are good enough, they are willing to divert some or all the Mars colony ships. **What resources do they need to take to the ship and what will it take to get them there?** In response to comments and answers: The time limit is flexible in the service of storytelling. I obviously chose it too short, but it should not allow for complete preparation and a 99% certainty of survival. That said, for all intents and purposes a single person on board with enough supplies could live out their life on the ship, it seems to be that safe. But the new crew is going to have to get aboard with some stuff that they have to figure out on the way if they want to make it work in the long run. A lot of equipment is ready to go, thanks to the Mars mission. That probably includes a whole set of Hydroponic-ready plants that cover nutritional needs (though only tested up to few years with adults). Of course, the equipment was meant for only 100 people when at least ten times that will go on the alien ship. Of the cryogenic pods, only a few show status lights that appear to indicate all is well. The insectoids can't be revived yet (an attempt will result in the alien's death) and are not playing an active role in the story, but their presence obviously does. (Thanks liljoshu!) All the other insectoids were frozen where they died when the ship lowered the temperature to somewhat below zero degrees celcius. It's unclear what they died from, but there is no sign of disease or violence. There is also no evidence of a queen or other special types or aliens. The exact cause remains unknown during my story, though the leading theory becomes that they were hit by an intense radiation burst. Finally, one of the landing ships is pulled from the hangar to a safe distance and experimented on to try to disable the computer or drive system. It does not end well, so the decision is made to not tamper with the much bigger versions on the generation ship. [Answer] Food, water, air, shelter, and a few other environmental criteria are all humans -need- to survive. To this end, the ship is obviously providing these. You mention the frozen insectoids come in both dead and still-frozen varieties. The biggest challenge then isn't the physical needs then, but the insectoids. The dumb response would be kill the living-yet-frozen ones and take over the ship. The ship, not killing humans on entrance, but respecting visiting living things, implies that the insectoids hold life in high regard (my guess is that's probably why they avoided Earth). They're also more technologically advanced than humans. It's dumb because follow up probes will trigger that humanity is an aggressive killing species, at which point we've started war with a technologically superior species that can obviously reach our world but we don't know where they came from if we hurt the frozen occupants. However, it IS a golden opportunity. They've obviously lost crew and may not have compliment to survive on destination. Effort should be taken to identity the roles of the dead crew, and provide replacements. Also, since you know how their vision is different, rig up a display to show the videos of approach, discovery, and finding they're already dead and refactored show it shows in the displays the insectoids understand - so they know humanity's story there when they unfroze them. As a result, humanity will likely come out with an interstellar ally, and all the tech we didn't understand may end up being shared. Make it obvious that they're doing the best they can to care for the still-frozen crew members, and try to do repairs to the ship. Do NOT flush the hydroponics system. Replacing their food supply with your own will just cause strife. Bring in your own plants and hydroponics and place in the same region of the ship. We already have the tech for this. Even if toxic, plants from the hydroponics could still be pruned to keep them reasonable, and the biomass pruned off can be incenerated to carbon and other elements and used as fertilizer for our own hydroponics - a symbiotic relationship from the start. At which point it should be taken as a sign of "We're joining you in exploring the stars, we're of like mind." Since they obviously respect life, when the insectoids wake up, they'll see a new alien species who cared for them and joined them (without knowing that we're technologically behind them in some ways), and helped them set up colony on a new world (unthawing would take a bit), meaning you have the first mutli-species cosmopolitan colony that humanity is part of. If this is THEIR first colony ship, it means humanity and them have a long future together as partners. (Likely due to the unintentional fatalities). If it's not their first colony ship (unlikely but possible), humanity has avoided ticking off a much larger force while still making benefit. If humanity -doesn't- try to join for the ride though, there's someone else in the steller neighborhood grabbing all the good habitable planets. From a tactical perspective, it makes best sense to try to ally, join, and cooperate. And from survivability standpoint, if we were already planning colony ships to our own system, we should have an easy time "colonizing" a hospitable environment on a larger interstellar colony ship than we would the inhospitable planet we were aiming for for a shorter duration. We might load on a lot of supplies into storage space, but it's a fairly reasonable route. [Answer] I see several problems that make this unlikely. 1. The ship already killed everyone on board once already. 2. You need about 50,000 people to have a good genetic pool. Cryogenic storage of genetic material can alleviate some of that. 3. The mineral filters need to be changed regularly, you would need enough to last the trip or have the ability to make them. It may be best to look at the water supply itself to de-mineralize the water. Or replace the water. 4. New plants (and new dirt) for everyone. Is there room for animal life? If not, be very careful with the plants and have redundant plant types for every dietary need. You don't want, for instance, a fungus to mutate and take out your only sources of dietary phosphorous. However, if you can overcome those issues (and analyze the ship to get the info you have) in 4 months, it should work. On *Rendezvous with Rama* (by Arthur C. Clarke), the ship was swinging through our system using the Sun as a gravity assist. That gave us our short window to check it out. How is the ship accelerating and decelerating? I'd be tempted to blow the command section just so I can disassemble the engines to see how they work. [Answer] I tend to be pessimistic. There are a few points speaking against any survival chance... * The ship was built by a technologically advanced species * The ship was built exactly to support THAT species * The species building the ship had years, perhaps decades to prepare for this mission * The ship is huge, so it should have had redundant supplies * The ship probably contained specialist for everything (biologists, doctors, etc.) that may have been needed to keep members of that species alive * Despite all of that, the ship FAILED to do exactly that So, what are the chances that another species will survive exactly the same task, given that... * This species does not understand the technology at all * This species can only use parts of the ecosystem without danger * This species has only a very limited amount of time to gather supplies and people So, given these ideas, chances are slim. The best chances I see would be one of these: * Humans are somehow inherently better than the aliens to survive such a journey. Or, the other way round, somehow the aliens were unsuited for such a travel, perhaps some flaw that was only expressed itself in deep space. * Whatever killed the aliens was a rare event, something that can happen but doesn't have to happen, so humans could be lucky and don't fall into the same trap. Perhaps the mentioned radiation burst can happen accidentally, but it also might not during such a journey. In other words, the aliens simply had a streak of very bad luck. [Answer] A 4 month time frame is not enough time to analyse, design, produce, and ship the necessary modules to adapt the generation ship to support human life. The existing Mars missions are probably designed with regularly scheduled resupplies, and extensive monitoring from an Earth based mission control in mind. They wouldn't be suited for repurposing for supporting a populations for multiple generations. To put things in perspective it took 8 years to launch the [Mars Science Laboratory](https://en.wikipedia.org/wiki/Mars_Science_Laboratory#History) after the initial request for proposals. [Answer] I would fully agree with liljoshu, just a few more thoughts: 1) But what if no insect with authority to use any landing craft is still alive? I mean the ship parks itself on the orbit, and waits for someone with authority to give final order? From what you describe humans can not be certain, that any insectoid can be defrost intact. So possibly no landing. (is there enough place to take your own landing craft?) 2) If the ship was designed to go to Earth and changed their mind at the end, they wouldn't have much fuel. (simple logic: mass is expensive in space travel) Not big deal for frozen insects, but it may matter for generations of humans if the travel can take really long. 3) The most important thing that this mission can achieve is NOT colonizing some distant planet, but reverse engineer alien technology without making humans galactic pirates and outlaws. Assuming that there is a team that slowly understands part of alien tech that's the priority. So install Wi-Fi uhmm... satellite dish to communicate with Earth. Put there a team of young engineers, scientists, archaeologists, computer geeks, etc. People NOT specially suitable for any colonization. Their job is to learn this tech, send data back to Earth. Just keep reasonable sex ratio and frozen gametes, if they are really successful maybe their grand kids would colonize something. 4) Regardless of anything while installing human habitat better take a few non critical supplies from the ship. Yes, even an alien hair drier would be a huge tech gain. ;) 5) A few generations of humans would have real problem of lack of meds. Not sure how it's produced at that level. 6) It's a perfect start of a horror story - ship arrives at wrong planet, most of crew dead and the ship infested by some mammals... 7) Those humans at least killed one alien (while defrosting), destroyed one landing ship and presumably did much more damage. I would send them unarmed and select only volunteers who would swear that they would show no resistance if aliens would become aggressive or just panic. [Answer] Trying to Wake up the few surviving Insectoids in cyrostasis would be the best option because they may be willing/able to stop the ship from moving on to the next potential colony automatically, giving us all time to do all the First Contact stuff that both sides will most certainly want to get done. Once that is out of the way, and later cooperate to colonize that other new world that the ship was going to redirect itself to. And considering the ship just opened the door for them, and I doubt the ship's automated systems are dumb enough to think the approaching Earth vessel was another alien ship, this indicates a desire to communicate with and even trust alien life, hell if the alien ship has an onboard AI, that AI would likely be trying to figure out communications with humans, and vary well could have had that analysis figured out before arrival due to listening to Earth's radio signals during its approach, likely being the reason it concluded it was safe to let humanity come aboard. I find this video on First Contact a vary interesting view on the long process of, and how that process would usually be completed long before the two species ever directly meet each other in a setting with no FTL: <https://www.youtube.com/watch?v=igZi4iyJiq0> <https://www.youtube.com/watch?v=thdC-HlRHWg> [Answer] 1. Why would you use a closed software ecosystem for external communication? (macs ;)) 2. Possible, yes. Probable, no. As Assimov asserted, the liklihood of an intelligent species existing within our species lifetime is so remote as to be implausible. These aliens may have been dead for millennia, and the ship has preserved the bodies. Cryostatis would be possible if the aliens share a few characteristics with our grasshoppers (anti-freeze in the blood and different cell structure from humans) Humans would have to import and use their own technology on the ship for all of their own needs, similar to Gateway (F. Pohl) [Answer] I do not know exactly what kind of story you want to build, but as others said, the chance of success is so small that it cannot seriously be taken into account. If you want a more credible story I would suggest that you modify it to something like: 1. The ship had a critical failure somewhere in the solar system. A vast majority of the on board population was lost to this. 2. The minimum crew is awaken by the ship, they initiate contact with humanity as they need help (manpower and resources). They are generally peaceful but the ship is capable of significant defense. This because if they are not peaceful we are easy pray and if they cant defend at all then they are easy pray and on both cases no standoff for intrigue can be made. 3. You can have a plot conflict between humans who want to help them and cooperate and humans who just want to capture the ship, kill them and take the technology. Sub-plot intrigues can be made with the timing of discovering certain elements, like how many are left, how good the defense is, how opened they are to communication etc. 4. Evolve the story into something where the ship is rebuild, some sort of technological transfer is made, humans join them, maybe in an extended and rebuilt ship that would properly sustain both populations. 5. you can have a sequel with the voyage to the other world and stuff like that. A ship that would not have a very important component with a lot of redundancy that would awake crew to save it is not plausible. It is just bad planning. Of course you could have automatic ships, but then you would not scout the possible systems with colony ships, you would have drone ships that report info back and the first contact would be with something like that and not a colony ship. A story where humans manage to do in a limited time something that the creators of that ship could not do is not believable if the intended audience is over 10-15 years old and is interested in tech. ]
[Question] [ Because of an error in the interpretation of the Mayan calendar I just discovered, I know now that Earth will be destroyed on March 13, 2021 at 11 o'clock in the morning, time zone of Palenque. I could rent a small time machine and will travel to the past to save the human species by achieving a self sustainable, inhabited by approximately 1000 settlers colony to be on Mars by 2020. My plan is helping the Soviets to win the space race to the Moon. If this happens, USA will put all their effort into conquering Mars. I estimate that if Russians land on the Moon by 1970 the Americans can land on Mars by 1985 and establish a permanent occupation since 2005. My time machine is very small and very expensive. I need to know the simplest change possible (espionage, sabotage, bribery with lottery, rifle shots) capable of achieving this change in history. [Answer] Save Sergey Pavlovich Korolyov. He was the mastermind of basically all of the U.S.S.R.'s space equipment, and he was flying circles around the U.S. scientists until he died in 1966. We don't really know exactly what happened to him. He might have had cancer in his abdomen, he might have had a botched surgery. Either way, on January 14, 1966 in Moscow, Russia, Sergey Korolyov went into the hospital for a fairly routine operation and did not come out. If you want the Soviets to win the space race, interrupt this event. One thing that we do know is that Sergey was getting sick, hence the operation, and either his cancer was too advanced or his doctor was bad, so your best bet is to get him into the hospital sooner. Part of the reason he died was his time spent in concentration camps, but you can't mess with that without risking him never getting into rockets, so it's best to just keep him alive after he's already in. Now, a man goes to the doc. when he feels sick, except Sergey didn't listen to his doc. for a long time because he was so devoted to his space toys. I recommend lightly poisoning him at some prior time so he has to go to the doctor and they can find the cancer/ulcers sooner and either get the cancer or get a better doctor to operate. Naturally, the government kept a pretty close watch on this guy, but there was plenty of time for him to get poisoned. Just pick your moment, slip him something freaky enough to get him to the hospital but not so freaky as to kill him. I recommend Rifampicin, an antibacterial commonly used to treat tuberculosis. Sergey didn't have TB, but an antibacterial can't hurt. Common side effects include vomiting, diarrhea, and, best of all, red or orange sweat, urine, and tears. That should certainly get him to a doctor. Also, another cause of orange urine is spinal abscesses, so the doc. will surely give him a thorough inspection. Additionally, Rifampicin wasn't used as a medicine until 1971, well after it would be used to save Sergey, so the doctors wouldn't jump to it's use in creating these symptoms. Rifampicin comes in tablet form and can be easily crushed and added to food or drink. A small amount should do, so it's no trouble to take it with you, or, since it was invented in 1957, you could try to find some "in situ". [Answer] Although the Soviet space effort is and was presented as a smooth running, monolithic example of Soviet efficiency and superior science, it was internally a chaotic mess, riven by rivalries and factionalism. To compound the problem, while the Soviets were initially able to get the jump on the Americans with Sputnik and the early manned space program, by the mid 1960's it was very apparent that Soviet rocketry had stalled. The "brute force" approaches of the early Soviet program may have developed the massive R-7 booster/ICBM, but American technology had made considerable progress in all kinds of areas, from miniaturized computers, the ability to reliably produce and handle high energy cryogenic fuels to fairly startling advances in rocket engine design. The F-1 rocket motors of the Saturn V are still unmatched for sheer size and power, and while the monster Saturn V launch stack used 5 of thee beasts to lift off (generating @ 35 GW of energy in the process) the comparable N-1 ganged *30* NK-15 engines for its first stage... [![enter image description here](https://i.stack.imgur.com/J71NY.jpg)](https://i.stack.imgur.com/J71NY.jpg) *Saturn V compared to the N-1* The real problem isn't to be solved by Korolev or Chelomei via technical means, but much, much higher in the Soviet hierarchy. The lack of interest in space exploration by the Soviet Strategic Rocket forces and the mercurial temperament first of Khrushchev, then after his overthrow by the different priorities of Brezhnev, First Deputy Premier Alexander Shelepin, and KGB Chairman Vladimir Semichastny, meant the N-1 project started late and was always underfunded. So, how to fix the problem is to look at one of the alternatives proposed in 1961. Korolev proposed a lunar mission based on what came to be known as Soyuz, assembling the lunar mission in Earth orbit using multiple launches. This program, while technically ambitious, does not require the massive leap in technology that the N-1 represented. By using "assembly line" production of the booster and many of the spacecraft parts, quality control is improved, and any launch failures can simply be replaced with another launch a short time later. The Strategic Rocket Forces may find this acceptable since high rate production of the new booster will allow them to quickly replace older R-7 generation ICBM's with the new rocket, or an ICBM largely derived from the new rocket. [![enter image description here](https://i.stack.imgur.com/LBg1n.png)](https://i.stack.imgur.com/LBg1n.png) *Apollo CM compared to the Zond* The one critical piece in this plan was initially Korolev still needed an N-1 launch to bring the lunar lander and fuel into orbit, but you can speculate that with a high rate of production and launches, Soviet space experience and technical refinement might allow all the pieces to be lofted by existing boosters in the final configuration. [![enter image description here](https://i.stack.imgur.com/I3kaL.png)](https://i.stack.imgur.com/I3kaL.png) *LK compared to the LEM* This is still a fairly primitive and cobbled together system, especially compared to the much larger and more capable Apollo CM and LEM, but it has the advantage of starting earlier, having the potential to attract more internal support from the Soviet hierarchy and allow the USSR to reach the Moon first. [Answer] Stop President Dwight Eisenhower from creating the National Aeronautical and Space Administration (NASA) in the later 1950s. This means the American space effort will be divided between the Army, Navy and US Air Force. Soviet space program was hampered by rivalry between several competing agencies. For measure if you could unify the Soviet space program to be organized, run and administered by a single agency in the manner of USA's NASA, then this should give them the edge in getting to the Moon first. Alternatively, ensure that President Kennedy doesn't decide "to go the Moon" either by nobbling the advisers who proposed what would become the Apollo Project or demonstrating your time machine to convince the Kennedy Administration that the Apollo proposal is a bad idea. [Answer] Assemble a file on German scientists in NASA and their involvement in Nazi crimes against humanity. Make a note where the most graphic pictures of places like [Mittelbau-Dora](https://en.wikipedia.org/wiki/Mittelbau-Dora) can be found in the early 1960s. Survivors, too. Have the time traveler send the documents to various newspapers in the US, and also to WWII survivors who have risen to prominent positions. Possibly each gets a slightly different package, so each can publish their own "scoop" ... [Answer] Compile everything you can about our *current* rocket science, print it out on actual paper, and drop it on the soviets' lap right after World War II. Research the early stars of their space program to know who to hand the stash to. Maybe much of it will be useless without all the context of modern industrial society, but let them scrape the gems they can use. [Answer] In our world of advancing technologies, being the first, doesn't always mean success. There's a concept called "second mover's advantage" in the business world. There's a mystique and advantage to being first. However, being second, offers the ability to see why pioneers fail and what works. I think it's just a matter of persuasion, knowing this. [Answer] **Steal Apollo Data** Collect all the data you can about the Apollo program. You need blueprints, at least. The more you can get, the better. Get data for Gemini and Mercury, as well. Once you have the data, deliver it to Moscow. The earlier after the US decided to go to the moon, the better. Ideally, make a soviet spy stumble upon it, so you don't have to worry about getting the USSR to trust you. Unlike with delivering them modern data, this is within their technology, so the Soviets could replicate it and launch with that. ]
[Question] [ In my story, a portal is opened from the Earth to an alternate world. However, this world is toroidal in shape and has a surface gravity equal to that of Earth. It rotates around an axis that goes through the center of the circle perpendicular to all major radii, and its day/night cycle (assuming that it is inclined enough relative to its star that all (or almost all) of the planet will see sunlight at some point in most day/night cycles. At the location where the portal opens, conditions are very Earth-like (1 atm of pressure with similar Oxygen, Nitrogen, and Argon concentrations, comfortable surface temperature, and 9.8+/-0.1 m/s² of surface gravity after adjusting for centripetal force) and the toroidal shape is not obvious (i.e. on the outer equator). Some quick sketches of how it rotates (green torus is planet, yellow sphere is its star, black cylinder is the axis of rotation), distances and sizes are not to scale, that I made in about 2 minutes: [![Image of rotation](https://i.stack.imgur.com/QNLqs.png)](https://i.stack.imgur.com/QNLqs.png)[![Second image of rotation](https://i.stack.imgur.com/cJSQD.png)](https://i.stack.imgur.com/cJSQD.png)[![Image of rotation and orbit](https://i.stack.imgur.com/FX6uK.png)](https://i.stack.imgur.com/FX6uK.png) The axial tilt of the planet may be increased as long as the rest of the planet is moved so that the axis still goes the same way, if that is needed to not have parts in perpetual shadow. I know that this toroidal shape should not be able to naturally form, but assume that plot device/advanced aliens/a wizard made it stable What aspects of this planet would tip off the scientists that it is not a sphere like Earth? Would they see something in their surroundings or would they not notice until they either went far enough to see the toroidal shape directly or went into space? Note that I am not asking for some test to prove that it is toroidal, but rather, something that people would notice is different and would result in them doing those tests or conclusively knowing. It would also be preferable if an ordinary person with a high school education can understand this demonstration (though they need not be able to recognize it on their own or even have been taught in school about it). [Answer] The outside equator of a toroidal world isn't locally much different from the equator of a spherical world. Assuming a [physically correct toroidal planet](http://www.aleph.se/andart/archives/2014/02/torusearth.html) (ie. one that maintains its shape due to physics rather than unobtanium or magic), the most likely clue that something's wrong is varying surface gravity. In order to keep the toroidal shape from collapsing into a sphere, the planet needs a fairly hefty spin: for an Earth-like planet, on the order of a rotation every few hours. This translates into a 30%-50% change in apparent gravity between the outside equator and the poles. Alternatively, someone sufficiently observant would notice that the horizon distance is significantly anisotropic: for the "hoop" planet modeled on the site I linked to, the horizon is about 8900 meters away in the equatorial direction, but less than 4000 meters away in the polar direction. Since this is a physically-correct planet, variations in the direction of "down" will *not* be present: the planet is in hydrostatic equilibrium, and the surface is everywhere locally horizontal (give or take minor variations such as mountains and valleys). Most of the really exciting stuff that happens on a toroidal world (doubled seasons, odd day-night cycles, etc.) happens on the inner surface, and if you're there, you can tell something's wrong just by looking up and seeing part of the planet stretching across the sky. [Answer] You would notice some odd things when travelling. Take a point on the outside of the torus. Travel in a straight line in a certain direction relative to the surface, let's call that direction 'west'. After a while, you get back to the place where you started, but you're approaching it from the 'east'. This is what you would expect, because it is what happens on a spherical planet as well. [![enter image description here](https://i.stack.imgur.com/cUydM.gif)](https://i.stack.imgur.com/cUydM.gif) However, when you travel 'north', it will take a lot longer to end up where you started, and most shocking of all, you never cross the path you took the first time. [![enter image description here](https://i.stack.imgur.com/hQlm3.gif)](https://i.stack.imgur.com/hQlm3.gif) This clashes with a spherical planet, but it doesn't require much immagination to see that the path you took fits perfectly onto a toroid planet. [![enter image description here](https://i.stack.imgur.com/Z6IAc.gif)](https://i.stack.imgur.com/Z6IAc.gif) [Answer] ## Looking during the day If the torus is small enough, the other side will be visible in the sky. In this case, during the day at some point someone on the inside of the ring is going to look up and see something looking suspiciously like a planet obscuring part of the sky. This can later on be confirmed by telescopes to be part of their own planet. ## Star gazing If the torus is too large to see the other side during the day, anyone sitting out at night star gazing on the inside of the ring would find part of the sky occluded. Subsequent investigations with telescopes could provide incontrovertible proof they are denizens of a torus. ## Astute map makers Eventually cartographers are likely going to try to map the planet, and at some point, they will inevitably discover something is not quite totally spherical about their home. ## Bad cellphone reception Once cellphones are developed, people will most likely notice that at certain times and at certain places on the planet, they cannot receive a signal from the carrier's satellite. Due diligence will likely result in discovering the far side of the torus is occluding their cell satellites. ## Failed space launches If rockets are launched from the inside of the torus' hole and unexpectedly run into the other side of the torus, they will discover the true nature of their home. [Answer] **Looking at the Horizon** Depending on the landscape you might even see the different curvature by looking at the horizon. If the planet is covered with a kind of desert where you can look in each direction without getting blocked by dust or fog one might notice from a point at the outside of the torus, that the horizon of two directions (lets say north and south like in Ezras answer) is more far away, than the horizon in the other directions (West and East). One might as well see different curvature at the horizon, assuming that the differences between the outer and the inner radius of the tourus are very large (i.e. that the "hole in the middle" is big enough to make a huge difference). This does not proof, that the planet is a torus (and no scientist would assume that directly from this) cause there are other shapes with the same unequal curvature. But it might be enough to make them think about the shape and want them examine deeper into this. [Answer] ## Watch the sunset *No education required* If these scientists are deposited on the outside equator of the toroid, they probably won't notice anything different. The sun will rise and set as it does on a normal planet. The rest of the torus is occluded by the ground under their feet. Further, the torus is large enough that they won't be able to visually confirm that "north" and "south" have a much smaller diameter than usual. However, on the internal equator, just look up at midnight. There will be a huge illuminated stretch of green and blue "sky" above them. It'll be hard to miss. They will be looking across the hole at the illuminated internal equator. If they arrive before sunset or dawn, the sun will set much before it reaches the apparent horizon because the sun will be occluded by the spinwise or anti-spinwise portion of the toroid. ## Torus at Midnight [![Midnight](https://i.stack.imgur.com/DcueR.png)](https://i.stack.imgur.com/DcueR.png) ## Torus at Noon [![Noon](https://i.stack.imgur.com/kTf1X.png)](https://i.stack.imgur.com/kTf1X.png) (The renderings of my own make and I'm very new to Blender. Oceans and land will come later.) ## Assumptions * The toroid spins at 1 revolution per day. * The 9.8m/s^2 gravity is along the outer equator of the toroid. * The axial tilt of the toroid is sufficient to permit sunlight to illuminate the entire internal face of the toroid. (Sunlight can get through the hole.) * The toroid is large enough that the scientists can't see [Answer] **Gravity will behave *really*, *really* weird.** Assuming no technology has been used to alter the natural way gravity works, you will have extremely strong gravitational difference between the *inner* side and the *outer* side. When on the *inner* side, the opposite side affects you much more (gravity scales with the distance), but in the - from your point of view - upward direction. The extreme case would be the center of the torus where it would even cancel out (provided the mass distribution is somewhat homogeneous). Thus it could be possible to "jump through" the center to the other side (if the jump is strong enough and the jumping person/vehicle can survive the trip.) **How to figure it out if you can not move to the inner side or even a point where the horizon starts looking weird:** Assume we are on the outer side, the torus is huge and movement is restricted. 1. Drop an object from as far up as you can and measure the falling time. (Repeat a few times to reduce the impact of errors) 2. Mark (from your position) two orthogonal directions. 3. For these two directions move as far as you possibly can (but an equal distance) and repeat the measurement. If one or even both measurements start to deviate significantly (5%+) something is very wrong with your world… 4. If no significant enough deviation can be measured, go back to your starting point, [Answer] **Compass will be useless.** On a spherical space, assuming there's electromagnetism going on between the poles, you can always find one of the pole using a compass. No matter where you are on the sphere, if you follow "North" then you end up passing through the North's pole. On the other hand, on a toroidal space, there's no such thing as a pole. Making compass useless. If you find something equivalent to electromagnetic pole, then you won't be able to reach it (assuming it's in the empty space inside the torus). ]
[Question] [ I'm working on a story set in a generation ship traveling through the stars. Its propulsion is a solar sail, which will accelerate it over many decades to a substantial fraction of the speed of light. However, its inhabitants need power for electricity, and don't want to use nuclear power (or [radioisotope thermoelectric generators](https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator), RTGs), or fossil fuels. Many spacecrafts today use solar panels or RTGs for power, but the latter is not renewable, and the former may not be useful when passing through regions of space where the light from stars is dim. So, how can my ship be equipped to take advantage of renewable energy in space? [Answer] I'm going to summarize the comments and other answers. If you wish to remain true to science: ## There's no free lunch Despite everything you've been told there is no free lunch. ### Solar power is a bust Even as close as the Earth is to the Sun, PV panels are marginal at best and they are a very dilute form of energy generation compared to other types. As you move away from the sun, the intensity of sunlight drops as $\frac{1}{r^2}$. NASA does not consider solar as a viable energy source outside the orbit of Mars. You shouldn't either. ### Renewable Energy Source There is exactly one renewable energy resource available between the stars, this is **interstellar hydrogen**. There are many possible ways for you to use this hydrogen, but they all break down into one of two ways: 1. Fusion 2. Antimatter annihilation ## Having your cake and eating it too Your question makes it very clear that you do NOT want to consider nuclear power. Since you are presumably writing fiction, this means you can basically write into your story anything you want. You can claim humans found *magnetic monopoles*, *flubber*, or can use clean *Zero Point Energy*. None of these are actually real or viable as a means to power a space ship but if you insist on no-nuclear, you'll have to use some form of *handwavium* (aka [*McGuffinite*](http://www.rocketpunk-manifesto.com/2010/11/searching-for-mcguffinite.html)) to do it. [Answer] You have a few options as far as I can see. 2 of them you need to bring with you. You need them to be very dense in power generation because you don't have lots of space. *Bring with you* 1. nuclear power you have already nixed. 2. Anti-matter needs much less space, but does need some power to keep it safely contained. Also we can't yet generate enough to be useful. *reduce energy needed* 3. Put (almost) everyone in cryo-stasis and have enough energy source stored to last the journey. *renewable/pick up along the way* 4. Fusion. You can have a big scoop in front of the ship collecting hydrogen molecules to fuse into larger atoms. Currently the fusion machines we currently have are huge and dangerous. 5. Somehow learn to tap dark-energy and dark-matter. [Answer] **Space Wind** Yeah, it's [a real thing](http://www.space.com/22661-interstellar-winds-milky-way-solar-system.html). The main issue here, as with most renewables, is that you're not going to get much power from it. Not only that, but the real power is coming from sapping your forward momentum (like putting wind turbines on a car, you're stealing from yourself). This is technically renewable, but not advantageous over the nuclear option. There just aren't a lot of energy options out there. The idea is you'll have interstellar medium blowing past you. It has mass and it's moving with respect to you, that means you can reach out and harvest that energy. Either the kinetic energy, or as bowlturner suggested, collect the interstellar hydrogen for use in fusion. Yes, fusion is a form of nuclear power on your ship, but it is renewable. It's also how you got going in the first place, except the fusion was from a star. Alternatively, you need to leave a beaming station near a star behind you to beam energy into your sails and your on-board batteries. This will allow you more power and a longer period of acceleration. [Answer] What do you mean by *renewable*? I think the common use is something that you won't run out of, or something that's not depleting a previously made stockpile (that is, not fossil fuel). I think what you mean here is something external to the ship rather than something you brought with you. But really, why? And in some cases, it's hard to make the distinction. First of all, what's your energy budget? Look at other questions concerning how much energy it takes to accelerate the ship. It's more than the entire energy consumption of Earth now, by orders of magnitude. That's with billions of people and all the heavy industry. How much energy will the occupants *need*? The amount is a tiny tiny drip in the budget needed to accelerate and then slow down the ship. ## ride the brakes So what's wrong with tapping off a little of that? Planning a separate power source that lasts indefinitely in case the primary source is lost and they can't slow down at their destination and are doomed to cruise forever at relativistic speeds, then at least they can just keep living like that? I'd like to point out that one storage reservoir of energy is the moving ship itself. Like I said, enough for a Type I civilization back home! You need to slow down anyway, so wouldn't it be nice if you could somehow utilize some of that energy as a side effect, as well as not having to *spend* that much energy *for a second time* to slow down? A Bussard ramjet might not actually give a gain over drag, by modern calculations. But if you're *breaking* that's not a problem and the drag only adds to your breaking! Running the ramjet at a minuscule level during the cruise phase will provide power for the internal use of the ship, and make about as much of a dent in the ship's progress as the surrounding dust and gas would have anyway. For breaking, there is also magnetic and electric scoops. The ramjet might not work well enough no matter how well the engineer it, so turn that on its head and make the scoop as *bad* as possible instead, and you have a parachute. Without having to gather the hydrogen and feed it to a fusion engine, you can just use the energy of it passing through the scoop as-is, in the manner of a windmill. A long conductive tether can provide for magnetic interactions with the galactic magnetic field, and serve as a break and a huge source of electricity. Maybe you get a laser boost from Earth to get moving for a short time and then have to run the break the entire rest of the journey since the breaking thrust is not as large as the launching thrust. Or maybe you cruise for some years and slow down when you get there, able to break quite fiercely. In the latter case, you can still run the break by a minuscule amount to generate power. The amount of power you need is orders of magnitude less than the amount of kinetic energy in the ship, so you won't notice. [Answer] Robert Forward is your friend. To accelerate a light sail to near $c$, the sail is powered by banks of terawatt lasers in close solar orbit (the general version of this is to have the solar power stations and lasers orbiting Mercury, but you can arrange this however you like). The sail rides on the power beam, and as it moves farther and farther away from the Solar System, giant fresnel lenses suspended in space focus the beam on the starship. (see <http://www.lunarsail.com/LightSail/rit-1.pdf>) [![enter image description here](https://farawayworlds.files.wordpress.com/2010/07/light-or-microwave-sail.gif)](https://farawayworlds.files.wordpress.com/2010/07/light-or-microwave-sail.gif) Terawatt beams are a *lot* of energy, so it is quite feasible to tap a bit of the energy shining on the lightsail to reflect on a power conversion device on the spacecraft itself to provide "renewable" energy. Since it is essentially Solar energy, it fits the definition of "renewable". The added bonus is the system as described can be used to decelerate. The two tricky questions are: will there be anyone manning the laser and lens system when it is time to decelerate, and; will the system function with enough efficiency to decelerate a lightsail moving at a large fraction of $c$? Forward himself suggested a much more modest performance for the system. [Answer] Summary: a [Bussard Scoop](https://en.wikipedia.org/wiki/Bussard_ramjet) is your only hope, but it is a very unsafe bet. As others have pointed out: no, it cannot be done in the traditional sense of "renewable energy" as we know it on Earth. Space is terrifyingly empty of **everything**, including energy to harvest. But I want to ask you to challenge the premise. My question to you is this: # Did you mean "renewable" or "sustainable" energy? Why do you require your energy source to be "renewable"? Is there a story element that requires it, or did you tack that label on in hopes that "renewable" means "good"? Where "good" in turn means "sustainable", "does not produce waste", "reliable", "available", "does not use consumables", "just works and works for centuries"? If there is a plot element behind it, then as I said: you are bust. If your travelers' motivation for demanding "renewable energy" on their ship does not amount to anything other than "We just want it that way", then the answer from their ship builder will be a harsh but truthful "Then you are not going into space". Do keep in mind that travelling in space is not a leisure cruise. It is not for the squeamish and happy-go-luckies. There are some **hard** decisions to make, and you will not have several of the "luxury" options available to you in space that you have on Earth. Renewable energy is one of these luxuries. But if you were simply looking for an energy source that will sustain your travelers for centuries, then you have used the wrong approach by assuming that renewables are the only thing that works. The safest bet **is** nuclear power. Already fission power provides a quite ridiculous [energy density](https://en.wikipedia.org/wiki/Energy_density) in its fuel. [![enter image description here](https://i.stack.imgur.com/mnIAB.png)](https://i.stack.imgur.com/mnIAB.png) *Source: [xkcd 1162, "Log Scale"](https://xkcd.com/1162/)* Assuming [fourth generation nuclear fission power](https://en.wikipedia.org/wiki/Generation_IV_reactor), approximately 50 grams of nuclear fuel will sustain one person with electricity and other energy for a normal human lifetime. That is quite manageable. You are going to need much more in terms of other consumables and renewables for every person on that ship. If you were worried about having to haul fuel along, this is not a problem, because the premise alone means that you will be hauling stuff along to sustain the people anyway, and a load of fuel for nuclear power does not add any significant amount of weight. If we then assume fusion power, the energy density becomes even more ludicrously high. Assuming for instance that [the Polywell reactor](http://www.emc2fusion.org/) works... [![enter image description here](https://i.stack.imgur.com/NcM2a.jpg)](https://i.stack.imgur.com/NcM2a.jpg) *EMC2's "Wiffle Ball 8" reactor in operation.* ...then we are talking about needing less than 1 gram of fuel per person and lifetime. Also with Polywell you can use aneutronic fusion, which means no radioactive waste products. In its aneutronic mode, Polywell uses 1 atom of Boron and 1 atom of Hydrogen to make 3 Helium per reaction... Helium that is not radioactive and that can be safely vented to space. So I ask you again: why did you put "renewable" in the question? Was that really what you wanted? Or were you simply looking for a **sustainable** source of energy? You will never get one that works forever without making "landfall", near or in star systems. But you can get one that works for **a very long time**, in nuclear fission or fusion power. [Answer] I'll take the easy way out and more or less invent a technology based of of a branch of physics that's not mature yet: Your folks will use [Unruh-Energy](https://en.wikipedia.org/wiki/Unruh_effect#Unruh_radiation). Unruh demonstrated theoretically that the notion of vacuum [depends on the path of the observer through spacetime](http://math.univ-lille1.fr/~debievre/Talks/unruhrolla09A.pdf). From the viewpoint of the accelerating observer, the vacuum of the inertial observer will look like a state containing many particles in thermal equilibrium—a warm gas. If this `perspective change` can somehow be induced without having to reach near-light speeds, the false vaccuum could be harnessed. This will allow space travel via reactionless drives, and reduce the fuel weight to that of the Unruh effect modulators (whatever they may be). Since by definition there is no point in the Universe without vacuum energy, you literally can't run out. It's just a matter of deploying subtle enough physics to take full advantage of the effect. It's unclear, for instance, just how large the energy density that is recoverable is. I've heard physicists talk of a single cup's worth of volume containing enough vacuum energy to boil all of the earth's oceans, but it's not clear by any means what fraction of that is recoverable, especially at an early stage of Unruh-drive technology deployment. [Answer] Is your ship following the rule of cool aka "to boldly go where no man has gone before."? Renewable energy sources in our time usually expect to have some storage/distribution infrastructure built around them - you're not taking your wind turbine/solar panel with you when riding e-car. *In hundreds of years before launch, automatic refuel stations were deployed along the expected path of generation ship to process interstellar gas into more convenient form of energy to be collected; the mission was to establish safe route and avoid having too much generations to die on ship; thus, higher acceleration and no dangerous technology onboard* Or, the stations may have alien origin and be scattered across galaxy - so the crew gets bonus points for being pioneers (without previous multi-stage launches to meet..) [Answer] **Piracy**: Travel via busy transport routes and keep nicking people's energy cells. Downside: Only works in a which includes populated space. **Trade**: As above, but more boring. **Big batteries**: Have extremely good power recapture, lots of huge batteries and travel via star-systems rather than in a straight line. Downside: Probably not possible using actual science, but handwave the battery technology enough and it could work in a story. [Answer] Since the 80's almost all space missions have used special solar panels to cover the energy demand on board, but if we need to travel much further in space, we would need a different form of energy, which could be produced on board, not by the Sun, which might be pretty far away from the ship to count as an energy source. Even in our solar system, if we decide to travel to one of Jupiter's moons (no further), the Sun being so far away from us, will not count as much as a viable energy source. On Pluto for example, the Sun looks almost like any other star, so we need to consider all the energy that can be produced on board as a viable energy source that can power all the activities that are taking place on the ship. Lately, it proved that human waste could be a good source of clean energy. [Human pee is a good source of clean energy](http://www.alternative-energies.net/human-urine-is-finally-considered-a-clean-energy-source/) because about 5 liters of urine can produce 1 liter of biogas. Giving the fact that an average person produces more than 1 liter of urine per day, the mission, which may consist of four to six people can produce enough biogas to power their daily activities. [Answer] The spacecraft is built like a giant "joule thief" and uses the planets' and stars' magnetic field to create electricity when it passes through. Incidentally that protects the people inside the toroid from radiation damage. [Answer] Although this is kind of close to fossil fuels: Could your space ship not just rely on bio mass as a fuel source? All organisms create waste which can be used as a fuel source. Unfortunately this does mean that you lose the option of travelling indefinitely by recycling bio waste into food and other useful materials. ]
[Question] [ A time traveller wants to save medieval Europe from famines by introducing the potato. The plan is, on first sight, simple: Just bring potatoes back with a time machine, and convince people to cultivate them. Now he can make only one time travel, and bring a limited number of potatoes with him (say, about 50 kg of them). He certainly wants his time travel to have the biggest possible effect. So when and where should he land, and whom should he convince to cultivate the potatoes, to have the best chance that they spread over all of Europe? [Answer] About 600 or 700 AD, and convince some monks in Francia. * Monastries preserved and spread knowledge, not just on scripture but also on crafts and agricultural techniques. * Do it before the split of the Carolingian Empire in 877, early enough to have it firmly spread in all parts. The eastern part will influence Italy and central Europe, the western part will influence the Iberian peninsula. [Answer] One of your biggest problems will be convincing the population to eat them. The family of plants that potatoes belong to also includes such delights as deadly nightshade. In fact, virtually all of the species in the family native to Europe are poisonous. The edible species (potatoes, tomatoes, and others) are all native to the Americas. In the real world, tomatoes in particular were grown purely as an ornamental plant for decades after they were introduced to Europe; nobody was willing to eat them because the plant looked so similar to familiar plants that were poisonous. Real world explorers were able to get past this with multiple expeditions, bringing back multiple species, and eye-witness accounts of them being edible, given by trusted individuals able to talk directly to the monarchy. Your time traveler will have to work out a way to get over all that with just his single visit. It won't be easy. [Answer] The person who suggested monasteries in France may find it interesting that France was the most resistant to accepting the potato. Long after Central Europe, especially the Germanic states accepted the potato, French royalty was still trying to convince the populace that potatoes were safe. In the late 1700's, there was a little ice age in which grain crops failed and caused extensive hardship and starvation in France because of their continued reliance on grains versus root crops like the potato which fair better when there are late freezes. I have found it fascinating in recent years how the climatologists can date climate events and therefore demonstrate more literal and practical explanations for the up and down swings on economies and the respective civilizations. ]
[Question] [ To go to space and mine asteroids is expensive, but it is known that meteorites contain rare minerals in the core that are easy accessible because of the smaller diameter. The expensive material that is in the center of the asteroid is expensive because it is rare. But when the mission returns to earth with the load, the mineral is no longer rare, and the price drops - making the mission a loss of profit. How can the investing company keep the price of the product sufficiently high enough to have a reasonable profit margin lets say 20-25%, without losing popularity such as [the diamond cartel](https://en.wikipedia.org/wiki/De_Beers#Diamond_monopoly)? [Answer] The "real life" solution to the dilemma would be increase demand with availability. Basic idea is that the materials have applications that are uneconomical due to the materials being too expensive due to rarity. When new supply of the material becomes available and the price drops those new applications become practical and the demand increases. This prevents the price from collapsing. In practice the same people investing on the mining would also invest heavily on those new applications and that would be where they'd get their money back. You can also use derivatives to monetize changes in commodity prices. So the basic requirement is that increased supply must open new applications. And yes, oil, steel and aluminium mentioned in the comments are historical examples of how increases in availability of a resource can create entire new industries. [Answer] All told, there are two ways this could go down. Both have been touched upon in the answers of @Burki and @VilleNiemi respectively, but just to recap: **A) The quantity your company can mine is insignificant next to the size of the global market** In this case, the demand will not change significantly, so there's no need to worry about a market collapse. Some of the earth-bound mines might stop being profitable and go out of business, but since your space company cannot provide enough material to satisfy global demand on its own, the rest will keep going. Since the demand for most materials is increasing long-term, perhaps not even that will happen. Your profit margin is directly equivalent to proportion of your unit cost and the market price, still mostly dictated by the earth-bound methods. You will be able to make out like thieves, until everyone else catches wind of what you're doing and starts competing with you. **B) Your company is mining enough materials to significantly affect the global market** This is the Ville Niemi's scenario; the price will drop, but new applications will increase demand. Expect competition to spring up shortly. **Finally:** There is one *huge* advantage that your space mining company has; the material they mine and send to Earth is already in space. This instantly slaps another $4k-14k **per kilogram** (in current economic conditions) to the value versus Earth-mined materials, if there is any use for said material in space technologies or if it can be advantageously processed in zero-g. A company that mines the material on Earth would have to pay for the mining *and then* to launch it into orbit just to make it available for the same applications. This is in fact the principal reason why deep space mining would be considered on an industrial scale; if you're already in space, you can use it to get much, much more stuff into space than if you were to launch it. [Answer] The price for whatever the company is mining is most likely determined by the classical system of supply and demand. That means, if you double the supply, your prices will drop to something approaching half the original price. While that will soon increase the demand (because cheaper stuff might suddenly be interesting where it was avoided before), you will surely still have a significant price drop. That means, in order to not completely destroy your margin, you should not flood the market with your minerals. Adding a few per cent at a time should be okay and should be the thing to do for your space mining company. Note that this is *not* a suggestion to keep the supply short artificially. I was trying to hint at the fact that even through deep space mining, the amount of raw materials they can haul at one time might not be a substantial part of what is already on the market. On doing some quick research (that is: I googled "rare earth world market"), the amount of rare earths (as in rare earth minerals, not planets) traded each year seems to be 150,000 metric tons. One dragon capsule currently hauls 5 metric tons of cargo to and from the ISS. That makes me assume that it would be a long time until our deep space mining company could actually flood such a market in any way to substantially decrease the price. [Answer] I disagree with Burki, your company suddenly has a vast store of this rare mineral. In a well regulated economy they're stuck with the laws of supply and demand. In an unregulated one they're free to milk the system as long as they have deep pockets. They've got competitors who have high costs to get the small quantities of this rare mineral. Unless their competitors have very deep pockets the company can flood the market, put their competitors out of business and then jack up the price again leaving themselves as a monopoly. Repeat occasionally when other companies are getting uppity. ]
[Question] [ It is not hard sci fi, but I need something plausible. A spaceship falls on a planet and destroys itself. The area surrounding the wreck becomes highly radioactive. It can be because of the leak of radioactive fuel used to propel the ship; or because of the radioactive cargo the ship was carrying; or because of the reaction triggered by the impact with the ground. This area is now deadly for humans, like going near Chernobyl reactor was, right after the incident. I need something that could make possible again to go through the zone. An event - something near a hundred years after the incident - that abruptly changes the radiation levels, allowing humans to pass without deadly consequences. Since highly radioactive isotopes usually decay after a longer period of time, and not so suddenly, I thought about a climatic event that could change the features of the area. A volcanic eruption that covers the radioactive waste, a big flood that carries it away, an earthquake that makes the ground swallow the waste, a rainfall of some sort that lowers, even temporarily, the radiations. It's not the Earth, so it is plausible that a methane or a liquid lead rainfall would reduce the threat, don't hesitate to take it into account. [Answer] The wreck was highly radioactive when it crash-landed, and the lethal dose would accumulate in minutes. This was enough for the primitive locals to create strong taboos about the ship (a cursed and haunted place -- the radiation-induced hallucinations were most vivid) ## Option 1: However, most of the radiation was in the form of fast-lived [radionuclides](http://en.wikipedia.org/wiki/Radionuclide), and the main [containment core](http://mkaku.org/home/articles/the-physics-of-interstellar-travel/) of the ship drive was never breached. This means the radiation decreases exponentially with time. Most areas around the ship were relatively safe to visit for short periods within about 2 decades, but the taboo persisted. ## Option 2: Recently, a massive flood in this normally dry and parched wasteland washed away [the top 3 inches of soil](http://www.mphonline.org/how-to-decontaminate-a-radioactive-environment/) into the large river nearby, from where they were carried out to sea. Radiation in the area dropped by 98%. [Answer] Based on research that they're trying to do in Fukushima: * A plant or fungus spontaneously mutates the ability to consume material contaminated by radionuclides. It does this by binding the cesium (etc.) into a form that is stable and non-bioreactive. The radioactivity would still be there, but the Cesium (etc.) would be bound in a form that wouldn't easily pass into the human body or would be quickly excreted even if it were. Remember that the actual beta/gamma background radiation isn't as harmful as the effect on the human body when the contaminants enter the blood stream. [Answer] Since we're talking a period of 100 years.... how about simple **technological improvement**? The human society won't stay static, after all. Especially after watching a ship crash. That's bound to be a driver of new scientific inquiry. After 100 years of research, inventors finally create effective radiation suits and have the medical technology to treat radiation poisoning. So now, 100 years later, with the latest hazmat suit, combined with the natural reduction of radiation due to time, the crash site can be explored. [Answer] Who says the radiation has to go away for the area to be survivable? There are organisms that can withstand extreme levels of radiation. Meet **the toughest organism in the world**: [Deinococcus radiodurans](http://en.wikipedia.org/wiki/Deinococcus_radiodurans). As you probably know the problem with radiation is that it damages the DNA. However, deinococcus radiodurans evolved the ability to repair the damage very quickly. Humans could probably **adapt to radiation** in the same way. As an aside: The TV series "The 100" revolves around planet earth having been rendered "inhabitable" by nuclear warfare. But the people having lived on a space station for several generations were adapted to the radiation in space so that they survived the remaining radiation when they came back to the ground. --- > > I need something that could make possible again to go through the zone. An event[...] allowing humans to pass without deadly consequences. > > > If this is all you want to achieve you could have an asteroid impact near the original crash-landing site removing/relocating most of the radio active material. This could create many many small radiated spots while allowing several routes through the wasteland without deadly consequences. Even after the impact it would take people some time to discover ways to pass the area and maybe there will be some relatively unknown routes. Basically, you could have **a deadly maze** – think [Dead Marshes](http://en.wikipedia.org/wiki/Dead_Marshes) – allowing those who know how to pass through unharmed. Plus: Maybe there are shorter but more dangerous routes you'd only take in case of an emergency? [Answer] I like Serban's first two answers, but because you'd like more, I've *just* read an [article from Science News](https://www.sciencenews.org/article/iron-nanoparticles-snatch-uranium): # Option 3: "To retrieve the radioactive loot, scientists just need a magnet". Small, tiny nano-particles of iron can attract, and encase uranium, which has implications on future events that are similar to Fukushima and Chernobyl. The article also notes that they could be harvested from sea water. Your planet's ocean has a much larger amount of these than our ocean, and a storm surge floods the area for a short time, enough for these little buddies to clean your site. It can also take some soil with it. [Answer] A big meteor, with a uranium core, fell from the sky nearby the crash site. By hitting the ground it went critical and exploded into a natural nuclear explosion. The huge amount of neutrons released made the nuclides generate secondary explosions promoting their neutralization into less radioactive materials. A side effect was the vitrification of a large portion of soil. The radioactive levels are still a bit high, but survivable. Well, this might be a good excuse for a plot, if not scientifically perfect. ]
[Question] [ In many Science Fiction books and games, there are worlds or planet-like objects that are rings that orbit (or float around in space) (some examples being the Halo (from **Halo**) or the Ringworld (from the book called **Ringworld** by Larry Niven). After reading through a lot of the **Ringworld** book, it got me wondering. What would the size of a ring have to be to orbit a black hole, staying structurally stable. The size of the black hole would be stable (not growing) and being the size of an intermediate-mass black hole. [Answer] The answer is simple, although a bit of a cop-out: **Exactly as big as if it were around a star.** It's a common misconception that black holes have stronger gravity than anything else. But (ignoring general relativity) gravity is always $$F\_{grav} = G\frac{m\_1m\_2}{r^2}$$ where $G$ is a constant, $m\_1$ and $m\_2$ are the masses of the objects, and $r$ is the distance between their centers. What this means is that it *doesn't matter* if the object is a black hole or a regular star with the same mass - the gravity you feel from it at $r$ away will be exactly the same. What makes black holes special is that their mass is compacted into an area small enough that there is a zone between the actual surface (assuming there is one) and the place where $F\_{grav}$ is such that the $\text{escape velocity} = c$. (This is the space where light can't move fast enough to escape, which is why the hole is "black".) The edge is called the [event horizon](http://en.wikipedia.org/wiki/Event_horizon). Anything further away than that can (at least theoretically) escape, and behaves perfectly normally. --- As for the question of how big it needs to be to circle a star, that depends on how much [tidal stress](http://en.wikipedia.org/wiki/Tidal_force) it can support. Going back to the gravity equation, tidal forces can be described as the difference in $F\_{grav}$ based on the difference in $r$ from the nearest edge to the furthest edge. So the closer edge is "pulled" harder than the further one. (Objects in orbit are moving fast enough to be at the balance point between being flung away and "pulled in") There's a value called the [Roche limit](http://en.wikipedia.org/wiki/Roche_limit) which determines how close something big enough to hold together under its own gravity can get before the tidal forces will rip it apart. Separately, there's [tensile strength](http://en.wikipedia.org/wiki/Ultimate_tensile_strength) for how much force a given material can support before being pulled apart. You'd need some combination of these to figure out how close the ring itself can get. [Answer] It would have to be big enough to safely encircle the star that collapsed to create the black hole. When matter collapses to create a black hole, it does not extend its gravity well. It has the same mass as before. It is just concentrated in a much smaller area. So a ring world encircling a star that collapses will continue to work and orbit just like it did before, unless of course the actual collapse destroys it. Of course getting closer to the black hole is still dangerous. And you don't want to cross the [event horizon](http://en.wikipedia.org/wiki/Event_horizon). EDIT: At the surface of the sun, gravity is about 28 times that of earth. If the sun collapsed into a black hole, that same distance from the center of the hole will still be 28 times earth. but the new 'surface' will be a long way away. [Answer] If you're in orbit, you'll be in **microgravity** (aka free-fall) anyway, so **you won't feel the acceleration**. With a black hole, once you get pretty close, you get **insane tidal effects** that would rip you apart, but you'd have to be **well within the surface of the original star**, probably within a few thousand kilometers or so of the center for a few-solar-masses black hole for that to happen. --- So you can pick any distance from the black hole where tidal effects are not overwhelming. If I assume arbitrarily for a second that you care to find out where the gravitational acceleration is the same as that of the Earth surface, i.e survivable easily (no [spaghettification](http://en.wikipedia.org/wiki/Spaghettification)), and relatively easy escape velocity. For a black hole (or whatever spherical object) the mass of the sun, $g=9.8m/s^2=g\_{earth}$ at [$3.68×10^9$ m](http://www.wolframalpha.com/input/?i=6.67428%C3%9710%5E-11%20N%28m%2Fkg%29%C2%B2%20*%201.9891%C3%9710%5E30%20kg%20%2F%20%283.68%C3%9710%5E9%29%5E2) 3.7 billion meters from the central singularity, well inside the orbit of Mercury in our solar system (58 billion m from sun). At this distance, tidal forces should be essentially nil $<10^{-8}N$ for a human-sized object. The general formula for a small mass object being acted upon by a large mass M is: So multiply as desired given your chosen black hole mass. $g=G(M/r²)$ That would make your structure is $2\pi r$ that length, so about 23 billion meters around. That's so large that it would take a human about 1500 years to walk the length of it, if they walked 8 hours a day. --- More interestingly, what's the **minimum** distance you could build and remain un-spaghettified? At about a solar radius, the tidal forces for a 2m tall, 70kg human would be about $10^{-5}$N, which I think is quite tolerable. The minimum is likely even closer than that, but I can't find my old Misner & Wheeler Gravity book to look up lethal tidal forces. [Answer] This question is more specific than other answers have given it credit for. Consider: > > What would the size of a ring have to be to orbit a black hole, staying structuraly stable. The size of the black hole would be stable (not growing) and being the size of an **intermediate-mass** black hole. > > > This puts a definite range on the mass values of the black hole. This range starts well above the mass of our own sun. Stars over 3 times our sun's mass can turn into a black hole, but smaller than that, we haven't conclusively discovered any natural process than can create such a black hole. Furthermore, if you are being actually literal with [the definition of "intermediate"](http://en.wikipedia.org/wiki/Intermediate-mass_black_hole), that means we start the scale at 100 solar masses. The question also clearly specifies that this is a Niven-style construction. As such, the walls need to be high enough to hold in the atmosphere. Earth sea-level parameters give a characteristic height of about 8 km, and pressure falls off exponentially, so the radial dimension should be on the order of 50 to 100 km. The event horizon of a 100 solar mass black hole would be at about 295 km radius. The photon sphere is the closest that you could orbit. It is an unstable orbit, but we can allow for active stabilization and control systems and easily wave this off. After all, the same was claimed from the original Ringworld concept! At the photon sphere of our smallest intermediate-mass black hole (100 solar masses) will have tremendous tidal forces, and a 50 km structure is unworkable. Because of this, we would have no choice but to locate it at a more distant radius. But what accelerations can the wall tolerate? I'll say 1 g as a Fermi estimation to set the magnitude. Applying Newtonian tidal estimation: $$ \Delta h \frac{ G 100 M\_s }{ r^3 } = 1 g \\ r = 407,000 km $$ This is fairly nearly the distance between the Earth and the moon. This is the minimum radius for a ring which can withstand the tidal forces of an intermediate mass black hole. --- That answered the question, but as the saying goes, there is a fly in the ointment. In doing this calculation I actually undermined the construction principle of the Niven-type Ringworld. In that design, we have unobtanium to hold against 1g of acceleration over a large radius. In the scenario I analyzed, the tidal forces *alone* are enough to produce Earth gravity over the scale of the walls. And this is true if you're in freefall orbit in the first place (actually, that changes the calc by a factor of 2 I think). The logical thing to do would be to simply trash the unobtanium in the first place. You could get gravity by the tidal forces, so if this was a bike tire tube, you could live on the innermost circle of the tube or the outermost circle of the tube. You could even transit between the two, passing through zero gravity. Or, if you didn't want a full enclosure, you could expand the dimension to >100 km and have the space between the two surfaces unpressurized. This is fairly workable with conventional materials. Although, for this design you might need smaller tidal forces and, thus, a larger radius. You don't even need a ring at all. The principle would work just fine for two space habitats held together by a tether. But then you have other problems, like the lack of a sun to provide energy. I don't see any easy answer to that. There are some ways to get energy out of a black hole, but I these tend to focus on electricity production, and light production would necessarily be artificial. ]
[Question] [ I would like to know what would happen if a new virus arose which could not be cured and which managed to escape the infected areas (and any quarantine zones). In order to scope this question **I'm not interested in how humanity would adapt** I want to know about how the infected rates/death tolls over time based on patterns from historical epidemics. * Let's assume the virus is spread through body fluids (seems common enough) * No human doctor can treat it I want to know * Assuming there was no medical cure would everyone die? * Or is it likely some people would be naturally immune/recover? * What would happen once the virus infected everyone? Would the entire population die off? Would it subside (like a predator) then reassert itself when humanity has rebuilt itself? The answer I'm looking for will look at major outbreaks from the past and extrapolate what would happen if something similar happened today. Just to repeat myself I'm not looking for humanity's response to a global contagion, I'm looking for the patterns the virus would follow. [Answer] First, the deadliness of a virus can vary widely from mostly harmless (Herpes) to very deadly (Ebola). However, note that even for Ebola, there are people who survive without treatment. Indeed, Ebola [cannot be cured;](http://www.medicinenet.com/script/main/art.asp?articlekey=179802) all the treatment does is to try to keep the patient alive for long enough that the body can fight the virus by itself. An important question is how quickly the virus mutates. Most viruses mutate slowly, and therefore if you survived once (or got vaccinated, if a vaccine can be developed) you're immune to the virus for the rest of your life, or at least for many years. Other viruses, like Influenza or HIV, mutate more frequently, which means that even if you're immunized against one strain, you'll still be unprotected to another strain (this is why Influenza vaccination is repeated every year: It's always a new strain that becomes prevalent). Note that there's also an evolutionary force on the virus: As soon as it spreads too violently, it will have a harder time to spread further, since all potential hosts are already dead or immunized, and moreover will put the more effort into avoiding the infection, the more deadly it is. Therefore there's a selective pressure on the virus to become less deadly, or less infectious. Probably as long as there's no cure, ultimately an equilibrium would be reached like for measles or mumps in the middle ages, where it is common, but not as common to threaten humanity as a whole. Of course, as soon as a cure of an effective vaccine is developed, the equilibrium will change to less ill people, if the virus will not be eradicated completely (as happened with smallpox). [Answer] The patterns viruses take is highly varied, which gives scientists little to go on. Major factors include: * How contagious is it? * How long is its incubation period, if any? * How deadly is it? * How well does the human body adapt to new versions compared to the virus' mutatability? * Did it intend to kill its host, or was that an accident? These are not additive, so you can't just add contagiousness+incubation+deadly and look that up, they should be treated as independent dimensions, creating a hypercube of options. For instance (glossing over a ton of details in each example for brevity): * Flu is highly contagious, but the human body adapts to it pretty quickly. Accordingly Flu spreads like a wildfire, but quickly extinguishes itself every year, falling back to its "flame keeper" in China where humans, pigs, and birds intermingle enough to keep things alive. Without that "flame keeper" producing new variants, Flu would not be a major issue today. As is, it is dangerous enough that humans make minor lifestyle changes to reduce its transmitability, such as masks. * The common cold is ubiquitous, so it never quite dies. There are a plethora of variants going around at all times, so its hard for the body to keep straight which ones it needs to protect against. It is also very non-lethal, more of a nuisance, so there is little pressure for humans to change their lifestyle to combat it. * Ebola is highly deadly, and very contagious, but it kills its victims too readily. Accordingly, Ebola outbreaks look like a small spark in gunpowder. It strikes quickly, hot (killing people on the way), but subsides quickly just the same, because it is so dangerous that humans will completely change our lifestyle in order to combat it. * Poliomyelitis actually lived alongside us for thousands of years without an issue, until sanitization decreased our ability to develop immunity to it in small doses and it became the Polio we know today. It struck people so hard and so fast that we actually crushed the virus under the force of our intellect. * The Plague traveled by rats, making it tremendously contagious, and we were highly susceptible to it. It basically ran unabated until it literally ran out of victims... the latest theory is that some portion of humanity accidentally had immunity to it, and that is the portion that reproduced to spawn the next generation. It's only a game, but consider games like [Pandemic 2](http://skunksoup.com/2011/10/free-online-games/strategy/simulation/multitasking-management/disease/pandemic-2-disease-mutation) for more ideas that can should guide your research. [Answer] One of the best possible answers to your question is a stroll down history lane to the [1918 flu pandemic](https://en.wikipedia.org/wiki/1918_flu_pandemic). Unlike most viruses, the Spanish flu checks off every box in your question: * could not be cured * managed to escape the infected areas (and any quarantine zones) * the virus is spread through body fluids * no human doctor can treat it In the span of two years, it circled the globe twice, infected more than a half billion humans (1/3 of world population at that time), had a 10-20% mortality rate, and killed 3-5% of the world population at that time. [Answer] A virus that kills people is not a human virus. The most deadly viruses are usually those who usually infected animals, but were somehow recently transferred to humans. It is not an aim of a virus to kill its host. The aim is to spread. As such, over time the most deadly deseases either become less deadly or humans selected who are not affected with it. This way an animal desease becomes a human one. [Answer] Small but important point here: # You cannot cure a person from a virus infection Read that again: you cannot cure anyone from a virus infection. Bacterial infections? Yes, antibiotics will kill the bacteria and thus remove the infection. But viruses are a different thing. Side-note: Are you still dousing your hands with disinfectants in hope of not getting a virus-born flu? You can stop now, because viruses do not give a hoot and a holler about ethanol and other disinfectants. They only work on **bacteria**. And you are very resilient towards bacteria that are on your hands. The hand disinfectant craze came because some people saw that hospital staff were doing this. But this is because hospital staff deal with people that are **not resilient against bacteria**, such as cancer patients that have no working immune system, which means that bacteria on your hands that are harmelss to you may very well **kill** such a patient. But for the average healthy human being, dousing your hands with the stuff (and smelling like you just downed a quart of vodka) is a sheer waste of time. Soap and water — thus **physically washing away the virus before it gets inside you** — is how you do it. The only thing you can do is to keep someone alive while the immune system deals with the virus infection. You can also pre-emptively prepare the immune system to deal with the infection before it strikes (vaccination). You can also boost the immune system somewhat during an ongoing infection which may change the odds for the immune system to deal with it successfully but by then you are pretty much relegated to a being cheer-leading squad for own body. From this your question becomes a matter of 1) how deadly is the infection once you get it and 2) to how many will it spread. If the answers are 100% and 100%, then the answer is: we all die. Thus far we have never had such an infection in human history. We have "infections" that reach 100% of the population, but that are not deadly (gut flora for instance), and we have had infections that are 100% deadly (or nearly so) but that do not spread very far. So far we have not had anything that does 100-100. Pray that nothing such comes along before we know how to keep a person alive no matter what they are infected with... [Answer] For an extreme case, look at what happened to the New World after contact with Old World diseases. It was a combination of diseases that did the damage but overall it was probably at least 90% of the population dead and some entire populations wiped out (it probably wasn't a 100% kill, but rather reducing the population to a point of non-viability.) The source of your pathogen is very relevant. The more similar to things already out there the more likely there is to be at least some resistance (for example, cowpox providing protection against smallpox.) When the degree of similarity is low the lethality can be very high as we saw in the New World. Also: When does it become infectious compared to when does it take it's host out of circulation? The previously-mentioned Ebola, while highly lethal doesn't spread very well because it doesn't leave it's hosts walking around spreading the disease. (It's primary spread is from the sick and dead to caregivers.) and: HIV, on the other hand, leaves it's victims quite capable of spreading the disease for a considerable interval after infection. What saved humanity from catastrophe here is HIV's lack of infectiousness. It has almost no ability to penetrate healthy skin and doesn't even fare very well against intact mucous membrane. Now, consider something with HIV's ability to stay infectious and dormant for an extended period with something that copes with skin better (say, gonorrhea) and the Spanish Flu would no longer be the standard example of how deadly a disease could be. [Answer] First and foremost, everyone would not be infected, let alone die. Look at Brazil and Peru and the tribes of the Amazon, many of whom still haven't been contacted. Since they have no human contact, they won't get non-airborne diseases from outside. Since you say it is fluid-borne, they won't be affected. This can also be demonstrated by the fact that when new tribes are contacted, two-thirds of them die out within the year (Tribes of the Amazon documentary, BBC Four). This is because they have not had any diseases from outside, so are not immune to them. --- It is unlikely to abate then resume. Many viruses have a life of just a few minutes outside the human body; even the more deadly viruses like Ebola and anthrax (though not technically a virus) have a lifetime of a few hours. For example, the Plague did this: killed off a load of people, then died out. Admittedly it was helped in London by the Great Fire in 1666, but in many other places it just died out. --- In the end, it's likely that a significant proportion of humanity would be killed; modern communication and travel makes spreading disease much faster than in the past so an epidemic can become more deadly. However, some isolated humans would survive and might be able to make use of the remaining technology and machinery to survive. [Answer] Another point which seems to have been overlooked: Can this virus infect human germ cells? That is, does it infect sperm and/or egg cells? If so, it is likely that the virus would evolve to be less deadly (killing the host is bad for things which live on the host) and, eventually, it would integrate into our genome. Our genome, and those of various animals, are littered with viral DNA. Right now in Australia koala bears are facing this event. ALL koalas except a small population residing on Christmas Island are infected with a virus that is currently being integrated into their genome. The virus impairs their immune system similar to AIDS in humans and it may end up wiping them out if it does not become less lethal as it becomes part of their genome. [Answer] If you're going for extremes, go read [The Stand](https://en.wikipedia.org/wiki/The_Stand) by Stephen King. A genetically modified virus, the Blue Virus, is accidentally released from a military laboratory. Starting with one single family trying to flee, the thing spreads at a speed unheard of, with a 90% of fatalities. It goes so fast that media dub it 'Captain Trip' and leaves behind a world of dead. Only an incredibly restricted amount of people gifted with a natural immunity survive. Them, and some wild species. Cats, dogs, cows are affected as well... So you want a more extreme bad guy? Easy, insects survive, nothing else does. ]
[Question] [ In my future setting on Earth (or an Earth-like planet; haven't decided), the fields of robotics and AI have taken off and we have intelligent, ambulatory robots. (They were initially thought of as machines, but, as is common in such settings, they have advanced and they are considered "human-equivalent" by many, with the courts slowly catching up.) My question is about power. I want my robots to be able to move freely around the world (no tethers). It seems like my options are either batteries (plug yourself in each night to recharge) or something passive that keeps enough juice coming in. For the battery option, how much battery are we talking about? Imagine a human-sized, human-shaped robot that is capable of movement, fine motor control, and "thought"; how big and heavy would a battery to support that for, say, 24 hours need to be? Can I physically fit that somewhere on-board? For the passive-energy option, do I have options other than solar (which would still require a smaller battery for night/indoors)? If I covered the robot's exterior with the best solar panels that we might be able to build in the next 200 years, would that be anywhere close to what I need? Is there some other way to achieve that end? How do I realistically power my robots? I am looking for answers that are technically feasible within a couple hundred years; I'm not interested in alien technology or magic. [Answer] This is a complicated answer since every piece of technology you mention is going to be improving over those 200 years. That said I think the answer will actually be a blend of several renewable resources. Take a look at this solar efficiency chart from NREL (National Renewable Energy Laboratory): <http://www.nrel.gov/ncpv/images/efficiency_chart.jpg> The gist of the chart is that energy conversion efficiency has been rising steadily over the last 40 years. Computers and other electric devices continue to improve by increasing or maintaining performance at reduced energy requirements. However, solar only covers your robots for half the day (give or take) but other advances such as the biobattery (<http://en.wikipedia.org/wiki/Biobattery>) could help make up for the differences in lighting levels. Biobatteries convert something like glucose into energy via enzymes; very similar to how plants and animals break down food for energy. These batteries could be designed with different enzymatic components allowing your robots to "eat" different materials to power a selection of batteries in the absence of good sunlight. Not too different from Futurama's robots which run off of alchohol. This gives them the human like trait of sitting down to a meal (or chugging a sugary beverage) to get them through the part of the day. [Answer] The power requirements are going to be highly variable. Just think about today's electronics -- you could put a set of AA batteries into your TV remote and have it work for years, but an identical set of batteries from the exact same package in your stereo remote dies in 6 months. More to the point of robots, you're going to have so many different options for how to implement movement -- servos, stepper motors, "muscle wire", just to name a few -- that it's really impossible to say with any certainty how much battery you'd need, let alone whether it would fit. That said, though, this is of course set in the future, and we are seeing pretty slick advancements in both miniaturization and output of batteries -- as just one example, my Samsung Galaxy S5, despite using more power for its larger screen and faster processor, lasts much longer on a single charge than my old S3 ever did, despite the batteries being roughly the same form factor. So I think it's quite reasonable to say that yes, you absolutely could produce a battery that is powerful enough to run your robot through the day, and small enough to live somewhere within the robot's chassis. Then again: Why? Using a day-long battery still tethers your robots, albeit the physical tether only lasts overnight (or whatever) -- they still have to remain close enough to be able to plug in at night. That means they can't join their human friends on a weekend camping trip, or hang out at the (power-less) lake cabin for a week. That's going to cause a lot of unnecessary grief. Why not give them an [RTG](http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator) instead? They sound scary, but when you get down to it they're primarily releasing nigh-harmless alpha particles easily shielded by the robot's own "skin" (or even your own!), let alone the shielding of the device itself. These things can easily provide power for many years, and when they need to be replaced a simple battery backup could keep the robot "alive" while the old RTG is unplugged and a new on plugged in. Of course, this would have an impact on things like radioactive waste when spent fuel is removed, and the luddites of the era might never get over the "radioactive" bit of the RTG and thus naturally (but quite wrongly) assume that they're walking atomic bombs. All kinds of fun social problems you could run with from this, in addition to the whole "robots aren't humans" aspect. > > **Safety:** > RTGs are significantly safer the fission reactors. With an RTG, the only reaction is a steady and unchangeable (albeit decreasing) radioactive decay of the fuel; with fission, it's a controlled fission reaction that at all times has the potential for control to be lost, result in Very Bad Things(R). > > > RTG fuels are chosen for emitting alpha particles, which won't even penetrate your skin, and for a high production rate of those. While this makes them far more dangerous should you ingest them (don't do that!), it means that any environmental contamination is far less worrying because it will lose its radioactivity in decades rather than centuries. (That's assuming we don't clean up the fuel, which of course we would!) RTGs are further designed with nigh-indestructable containers to further reduce the chance of environmental contamination. When Russia's failed Mars-96 probe re-entered the atmosphere, its two RTGs were believed to have survived re-entry *and* impact on the ground without damaging the shielding; thus while they've not been recovered, practically no one's worried about any contamination from them. > > > So to sum up: Yes, you absolutely could have a battery powerful enough and compact enough to power your robot, especially 200 years from now. You could even slap some solar cells on them so they could recharge their batteries (or at least conserve battery power) while outdoors in the sun. Or, you could go space-age and put the same thing we use to power many of our space probes into your robots, and add the "anti-nuclear" luddite social aspect to your world. And that's all without assuming any new scientific breakthroughs: Remember, according to Back to the Future, we should have [Mr. Fusion](http://backtothefuture.wikia.com/wiki/Mr._Fusion) by next year -- if it can provide the 1.21 gigawatts necessary for time travel, certainly it can run a measly ol' robot! [Answer] One of the promising forms of energy production that I know of, which isn't yet well developed enough but could take off and is scientifically sound, is [focus fusion](http://en.wikipedia.org/wiki/Aneutronic_fusion), as applied with a dense plasma focus[[2](http://en.wikipedia.org/wiki/Dense_plasma_focus)]. The advantages are that you can make a generator of practically any size and it generates electricity directly, using hydrogen (deuterium) and boron (currently, but other fuels can be used and you can come up with some fictional ideal fuel that gives a higher yield). This is what the cross section of the dense plasma focus looks like: ![dense plasma focus](https://i.stack.imgur.com/VynTa.jpg) This is futuristic enough, can be used for large generators as well as small ones you can fit on your robots and uses a relatively abundant form of fuel. You could even get fancy and have blue tubes for hydrogen and red for boron and create a super-futuristic heart for them :P # The numbers Lets see how much energy we need: Using [this calculator](http://www.health-calc.com/diet/energy-expenditure-advanced), I calculated that, at the maximum (hard work is why we have robots anyway), you'd need about `300e3 kJ` per day, if the robot was doing hard work all day for 24hrs, assuming it weighs 200kg, is 1.8m tall and has the efficiency of human muscle of course (the calculator includes metabolism etc. but lets just overestimate things to be of the safe side). Given the daily energy need of `300e3 kJ` which is equal to about `84 kWh`, and comparing with what US households use on average per day[[4](http://www.eia.gov/tools/faqs/faq.cfm?id=97&t=3)] (again going for the highest margin here), which is about `30 kWh` per day, that's almost 3 times as much. Nobody said this would be cheap! ## How much fuel for the needed output? Going by [this 2011 article](http://www.renewableenergyworld.com/rea/blog/post/2011/08/really-cheap-really-clean-electricity-from-boron) (and its claim of how much of the total boron production would be needed to cover worldwide energy needs in 2011) and the relevant Wikipedia articles, it seems we can get a `kWh` per `2.71 mg` of boron, or `227.64 mg` for our daily use. That's tiny and it means we can deal with a very inefficient conversion rate. It's already hard to get numbers on the amount of fuel needed, but what's for sure is that this process requires energy to be put in, so if the robot runs completely out of fuel, it would need a safety feature to keep enough energy stored to restart the process, much like how we have batteries for motherboards (this *could* be a great plot device but the energy is probably not much and it's easy to just plug it in and give it enough to restart the fusion process). ## Fiction advantages This may not be mature technology yet, but it's being actively worked on and is realistic, so it makes a convincing feature for science fiction and there's lots of articles around for more information, which can help flesh it out. It gives a *lot* of space for energy, allowing your robots to exert themselves a lot and even consume a lot more than I've estimated here. One problem is how much it heats up, but you can probably use the extra heat to increase the body temperature of your robots to human-like or use some fancy peltier device[[8](http://en.wikipedia.org/wiki/Thermoelectric_effect)] to either get rid of it or transfer it to wall-mounted heat-sinks or something like that. Using this, there's no need for solar panels, or wall sockets - they can probably store a kilogram of boron and as much deuterium (I think it's a 1:1 reaction) and run for days on end. > > Since this answer was downvoted for it's math, I'm adding this > addendum showing exactly how the above numbers are computed and where > they come from. > > > ## Calculation of energy required for robot > > > I start my estimate from how much energy a human being requires per > day, since the robot is humanoid and thus designed to do a human's > work. I used the largest estimate I could reasonably make, to give an > upper margin - the logic is, if our energy source can meet this > threshold, it should be ok in any case. I used [this calculator](http://en.wikipedia.org/wiki/Boron#Production), > with age at `7yrs` (since lower ages increase metabolic rate and give > a higher estimate), `200kg` of weight, `1.8m` of height and `24 hrs` of > heavy exercise. I sum both the energy cost of metabolism and energy > output and round to `300e3 kJ` (using metric on the calculator). > > > *Keep in mind that this calculator apparently is inaccurate or varies > a lot in its output - Saidoro reports that it gave him, with the same > inputs, from `274e3 kJ` to as as low as `144e3 kJ` for the total > energy, which is less than half the value I used here. Using that > value, we'd require half the boron etc. - the point of the > calculations is to primarily establish an upper bound, so they hold > and the outcome doesn't effectively change, despite the significant > change in the values.* > > > Converted to `kWs`, we get `300e3 kJ = 300e3 kWs` or `300 MWs`. > Converted to `kWh` so that it's comparable to the other numbers, > `300e3 kWs = 83,333 kWh`. I rounded this number to `84 kWh`. Over a > period of 24hrs this is a total of `3,5 kW per hour`. > > > The average household consumption is taken from [here](http://en.wikipedia.org/wiki/Tonne_of_oil_equivalent) which > provides annual and monthly averages. The monthly average is stated to > be `903 kWh`. Divided by `30` to get the daily average, we get `903/30 > = 30.1 kWh`, which I averaged to `30 kWh` per day. Dividing `84 kWh / 30 kWh = 2.8`, which I rounded to `3` even though I don't reuse the > number. > > > I tried to find information on how much fuel the device requires per > unit of output energy. All I could find was a mention, in [this > article](http://en.wikipedia.org/wiki/Boron#Production), that "If all of the world’s power was generated from > boron, it would only use 10% of our current production [of boron]". I > found the total energy *consumption* worldwide in 2011 from [this > source](http://en.wikipedia.org/wiki/Tonne_of_oil_equivalent) which appears to be `12675 Mtoe`, where `Mtoe` is `Megatons > oil equivalent`. I found the total boron production from [the > Wikipedia article on boron](http://www.renewableenergyworld.com/rea/blog/post/2011/08/really-cheap-really-clean-electricity-from-boron), which, as far as I can tell is > post-2011. The article states "Global proven boron mineral mining > reserves exceed one billion metric tonnes, against a yearly production > of about four million tonnes" thus I assumed global yearly production > is `4e6 t` which is `4e9 kg`. Ten percent of that is `4e8 kg`. > > > The global energy consumption converted to `kWh` is `1.474e14 kWh` > according to the conversions from [the Wikipedia article on Tonnes of > oil equivalent](http://en.wikipedia.org/wiki/Tonne_of_oil_equivalent) which is stated as `1 toe = 11630.0 kWh`. To get > how much boron we need per unit of energy, I divided the two `4e8 / > 1.474e14 = 2.71e-6` which is in `kg/kWh`. Since the number is small, it's beneficial to convert `kg` to a smaller unit: `2.71e-6 kg = 2.71 > mg`. > > > To get the total boron needed per day for our calculated `84 kWh` we > multiply by `2.71 mg/kWh`: `84 * 2.71 = 227.64` - the result is in > `mg`. > > > The original errors where: > > > * Calculating the energy usage per hour for the robot and stating it in the wrong unit. *This number was never used*. > * Performing the ratio of boron to Mtoe calculation and *then* converting to kWh. *This was an error due to reusing numbers from > other calculations - should have redone them all at the end - the result was that the boron calculations where backwards*. > * Not using 10% of the boron production. *This had an effect of the calculation showing the necessary boron being 10 times the actual > amount - the prior error clouded this fact however*. > * Not multiplying the boron per kWh by the total kWh needed. *While the outcome is practically the same in this case, since at even 80+ > times the boron needed, it still is very little, it was a serious > mistake that in another calculation could have changed the outcome*. > > > These errors have been corrected in the answer *and would have been > solved sooner had the downvoter stated the reason*. > > > [Answer] If we assumed massive increases in computer power efficiency in the future, the Fujitsu K (<http://www.fujitsu.com/global/about/businesspolicy/tech/k/qa/index.html#qa12>), which is good for a bunch of things, but not, unfortunately, thinking for itself, uses 12.66 Megawatts per hour. Even if we can compact the necessary hardware down and get an entire thinking robot out of the same power as a modern supercomputer, you'd have to produce a -huge- amount of power to get it all working. **Digestion** I think the easiest way to do an internal solution would simply be to have them break down items into an easily stored fuel, which they would carry around. Essentially, the robots would "digest" materials and foods (with the byproduct that they appear more human if they eat), grind it up into a concentrated, energy rich slurry, and burn that as necessary in an internal engine. Anything that can't be used in the fuel is simply disposed of cleanly, as we might do. Unfortunately, the order of power we're looking at is.. unfathomable. 1 kcal is 1.163 watt hours (and one w/h is 0.86 kcal, so this robot would need to eat 12.66Mw/h = 12,660,000w/h 12,660,000w/h = 10,887,600 kcal and the average adult male should eat about 2,500 kcal. You see the problem? <http://www.unitjuggler.com/convert-energy-from-kcal-to-Wh.html> **Nuclear** Apparently one gramme of the uranium we use in our nuclear power stations creates about 1MW of energy per day, or 0.04 MW/h (<http://www2.lbl.gov/abc/wallchart/chapters/14/1.html>), so potentially a teeny tiny fission reactor, which, aside from the scale, is being used to produce a lot of the world's energy right now, could produce enough power from 24 grammes of uranium to power it for one day. This is definitely possible. I couldn't find the size of a gramme of uranium, but I can tell you that you could fit enough uranium to power this robot for a month at least, from a glob the size of a tennis ball. **Solar** Externally, I'm not sure they could operate on sunlight alone. I think we're definitely looking at an internal fuel source, unless there's vastly more energy in the sunlight of whatever world they happen to be living on. Here on Earth, the sun produces 1120 watts per square metre on average, so it's likely that generally they'll get even less than this most of the time, even if they have a full square metre of solar panel showing on their humanoid form (how big is your head?) and the solar panels convert energy at 100% efficiency or close enough. **Summation** So, in summary, go nuclear. I don't think i'm mucked up any of my calculations, but if you spot an error, feel free to point it out. All of this assumes no radical change in architecture that makes thinking really energy-cheap to perform (clearly we've got a secret, because we manage it). If something came along to eliminate the need for all that hardware, then both solar and digestion become valid sources of energy. [Answer] # Energy Storage: Nanocapacitors A Capacitor is two layers of conductive material separated by a layer of insulator. They contain no moving parts, have no chemical reactions, and charge extremely quickly. Their power storage increases with the surface area of the two conducting layers, and how close together they are. In a society with nano-fabrication, or at least the ability to efficiently lay extremely thin wafers and use them in a circuit, capacitors become quite powerful, and might be viable for proper energy storage. We're currently orders of magnitude away from the power your robots would need, but Volvo had a concept car that ran off of capacitors built into the panels of the car body. <http://www.21stcentech.com/transportation-update-volvo-e-car-concept-runs-super-capacitor/> As a bonus, you could justify your robots to have a body cavity filled with layers of high-surface area material, that fulfills the same functions of a human's lungs and digestive tract. As a drawback, this introduces all of the other societal implications of industrial-scale nano-fabrication, which are hard to enumerate and predict. Don't know if you want to open that can of nanoworms. # Energy Transfer: Magnetic Resonance Coupling Electric circuits in an oscillating magnetic field can be made to resonate, like a pane of glass in a room with the proverbial opera singer. This principle can be used to wirelessly and directionlessly transmit energy to a receiver, with relatively low power lost to the environment. There are currently several competing standards, but the Alliance for Wireless Power has a device that can charge at a range of several centimeters. <http://www.rezence.com/technology/meet-rezence> This might also be the principle behind come of Tesla's unpublished party tricks, which are said to have extended through the room or into his backyard. 200 years might be enough to scale that up to a field the size of a room, or a building, or a space-station, as appropriate to your needs. [Answer] **Assumptions**: A typical human has a mass around 70 kg. They consume about 1.1 W/kg continuously(I'm approximating) throughout the day or about 96 kJ/kg daily. This together with the average mass gives about 80W continuously or 7MJ daily(rounded). They have a total surface area of about 1.75m and a volume of about 66L. A robot will need an amount of power equal to some multiple of what a human needs which varies based on efficiency. Probably a very large multiple. **Batteries**: Our best rechargeable batteries have an energy density of about 2.6 MJ/L and .875 MJ/kg, meaning it would take about 3 liters and 8 kgs of battery if robots take as much power as humans. That's a large component, but not impossibly so. However, it doesn't scale very well if the robots take more power than humans, if it takes 5 times as much energy to run a robot as a human(Which is a very, very small estimate) it's up to 15 liters, almost a quarter of your volume. And you need that volume for other components. There's also the issue of cost, high end batteries cost $300 per MJ and have to be replaced biannually with continuous charges and discharges. This cost stays constant regardless of how you subdivide the charges, batteries wear out when charged and discharged, not by time. **Solar**: Just isn't going to work. A human has a surface area of 1.75 square meters. They can keep maybe .75 square meters of that pointed at the sun continuously. When the sun is out. And it isn't cloudy. And there aren't any buildings in the way(No city-dwelling robots here). Current solar cells can produce 150 watts per meter. So you're looking at just barely exceeding the energy requirements of a human for half the day. Robots are likely to require far more energy than humans. This isn't going to fly. Or even walk. **Nuclear**: Could work. The issue here is shielding, The fuel is easily tiny enough, but you don't want people walking around emitting harmful radiation at all hours. If you can miniaturize the components enough that the robot could be built almost entirely around the power supply instead of needing the power supply to be a smallish component, this might be feasible. On the other hand, this would pretty much make your robots big concrete tubes with limbs bolted on, which may not fit your aesthetic. Kromey's RTG may be better, but I haven't looked at it in detail. [Answer] It would be interesting if [the technology to wirelessly charge your phone](http://www.nytimes.com/2014/08/07/technology/personaltech/powering-up-without-any-cords.html?_r=0) was expanded upon in the next two-hundred years. Of course the dream is that one day your electronics can wirelessly charge without having to touch *anything*, or maybe even just always be powered completely wirelessly, no batteries needed. So, the question really is, *how do we realistically come as close to that as possible*? In my view, there are several generic ideas you can pick and choose from before deciding exactly what technology you want to go with. ## Make each electronic device generate its own electricity Answers which involve eating, or having each robot have its own generator, or using some outside resource like solar energy to generate electricity are all included in this section. It seems more natural because its what plants and animals do. It's also very modular - everything only depends on itself to run. Most current answers seem to be in support of this section. ## Have devices capable of storing great amounts of energy in a small space Batteries for the most part, but could also be considered for fuel-like sources such as gas or hydrogen. We support gas stations for cars, if robots are human-equivalent maybe a new function of gas stations is that they can charge robots as well. The idea is that the energy we use to power our houses or such can be stored for later use and is **easily** refilled when it needs to be. ## Devices which run on electricity provided to them Most house-hold electrical devices are simply plugged into the wall and don't require a method of storage or generation. These are possibly the most user-friendly. You plug it in, you don't need to worry about refueling or putting it in the right conditions so it can generate its own power. I like the idea of the wirelessly charging phone in the first paragraph because its one of the few ideas (*that is actually in use today*) I've seen that fits into this category without just being plugged into the wall. You could also say something like bumper cars or electric-ran trolleys (*also known as trams*) run in this way. Imagine if the mat that can charge your phone could be easily attached to any surface in your home and thus, could run anything touching that surface. ## Combine and choose I feel like I should mention that when you take any *one* current technology and try to extrapolate it into the future there is a certain... *"Cars will all be flying by the year 2000"* type of feel to it. Most likely you will want several different technologies which, together, achieve the feel you want, because that will also be what will make it unique for your world. [Answer] To offer a third option, robots could be somewhat like humans by needing to regularly consume carriers of energy, such as oil, hydrogen or batteries and then excreting the remnants. The technology for this is available right now; it’s just not feasible as this kind of mobility is not a desired feature for robots for now. Your robots would not be restricted, as the energy source can be widely available and the robots can carry backup energy around with them – just like humans. [Answer] There are fuel cells which run on sugars. ([Here](https://en.wikipedia.org/wiki/Sugar_battery) and [here](https://en.wikipedia.org/wiki/Enzymatic_biofuel_cell)) The robot may be autonomous and take its own dose of sugar (with some water for the fuel cell) every now and then. Even if electronics become very efficient, (i.e. quantum computer, optic computer, etc...) the minimum energy requirement for a robot to do physical tasks is the same (Climbing up the stairs, lifting heavy objects, running, etc... would all require a minimum energy output based on physical laws, and figures cannot go below those values). [Answer] Turning my comment into an answer. 200 years is an incredible amount of time given our current rate of discoveries...so it's hard to tell what options we might have...though I would suggest our current ones are harshly limited and probably not feasible in a robot. Right now battery technology lags behind most other tech advances (most phones are 80% battery anymore...we've miniaturized electronic to the nth degree, but have basically failed to come up with a better electricity storage option.) Some more futuristic style advances: Lets say we get a much larger particle collider and we discover that ultimately a proton and electron are made of the same thing. A proton is thousands of times more massive than an electron...but if a proton breaks down into the same components as an electron, whats stopping us from rearranging these former proton particles into a much larger number of electrons? A single proton (also known as a hydrogen atom) can easily be taken from water, leaving a simple o2 cloud as it's exhaust and the occasional need to add water to itself. How far futuristic do you want to go? Our current computing has almost reached the limit as to how far we can miniaturize a computer processor. The 'next' step as some have envisioned is quantum computing. Instead of taking a million 1 bit transactions through the processor, the processor opens up 1 million dimensions containing one processor that does one calculation before collapsing (the scale of this is amazing...1 million calcs by one processor vs 1 million processors doing 1 calc each. It's this level that I envision an AI starts becoming possible). Heh, multi-dimensional parallel processing! Whats stopping us from opening 1 million dimensions and stealing a single electron from each before collapsing? added: really not a fan of the solar options...really not that feasible just because the varying degrees of sunlight availability. The pacific northwest has had entire months under clouds without seeing the sun. A volcano erupts and spews ash into the air and shuts off all the ambulatory robots that are so badly needed in the aftermath? It's just not that feasible to me. How about using the moon? It's North side seems to be full of ice (water) and it's horribly isolated...set up thousands of nuclear generators that create the energy needed, and 'beam' it back to the earth. I wonder if the technology to broadcast electricity in the same manner we currently broadcast radio waves will ever become feasible? ]
[Question] [ Take a large spacecraft. I'm thinking about 1,000,000 metric tons and 3,000,000 cubic metres, but I don't think a factor of 10 either way would change things. The ship is heavily designed and capable of atmospheric flight. There are *technobabble* FTL and STL drives. The ship can maintain several G for several days. The drives do not operate during this scenario, I mention the acceleration and delta-V to give an idea how strongly the ship is constructed. Think of the *Nostromo* from the *Aliens* movie -- steel frames and hull plates, not lightweight composites. Under ordinary circumstances, the ship is capable of controlled reentry, atmospheric flight, and takeoff. Now assume that this ship is left in low orbit, which decays over time because of atmospheric drag. (This will take some time, given the mass to surface ratio, but how long isn't the question.) At some point, the aerobraking accelerates and the ship crashes on the planet. What kind of wreckage will result? Will most of the wreckage be in a confined area? Can there be something which intrepid adventurers can actually enter and explore? Historically, there was the Columbia disaster. The Columbia disintegrated into [relatively small debris](https://commons.wikimedia.org/wiki/File:Grid_with_Columbia%27s_Debris_-_GPN-2003-00081.jpg). So did Skylab, yet the [tank](https://commons.wikimedia.org/wiki/File:Skylabfragment.JPG) was recognizable. I would like a [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'") answer, but I realize that's too much to expect. So I made it [reality-check](/questions/tagged/reality-check "show questions tagged 'reality-check'") instead. --- Alexander asked in the comment if it was tough and relied on aerobraking, or if it relied on braking with engines. My assumption is that it is tough, yet usually uses engines to brake -- toughness so that it doesn't need an overhaul after each landing, engines for controlled flight. Separatrix assumed that there would still be a crew. I was thinking of a derelict, no crew and the power for the computers and maneuvering thrusters is long gone. [Answer] Stronger is not better, unless you can reach really ridiculous strengths. If a ship reenters in an *uncontrolled* way, it will tumble and fragment. What can vary is what then happens with those fragments. Anything that is built like an anvil will just experience some surface melting, leave a long trail in the air, and reach the ground with a rather loud thump. Very much as a metallic meteorite does, if it enters at a very shallow angle. Anything that is build like a balloon (such as the tank from Skylab) will slow down quite rapidly in the upper atmosphere, losing only a bit of its outer layer, and the gently fall down to the ground. Satellite fueltanks are notorious for doing so, as they combine the requisite high strength and very low density needed for this to work. Note that the manned capsules such as Apollo, Soyuz, Dragon also fall in this category. They are very low-density, reasonably aerodynamic shapes that lost their worst velocity very high up, where they can do so safely without experiencing *too* much heat or deceleration at one time. They are also guided, a bit, to make sure they stay in the correct regime during reentry. Anything in-between will go through hell. Large panels, regardless of material, will very rapidly become small (sub-meter-size) pieces of panel. They are then subjected to blast furnace heats. Bits may survive, but not as much recognizable. For your vessel, which sounds as if it is build much like a navy frigate (heavy build, strong, but not massively armored), and which is reentering at the absolute minimum speed and angle possible due to natural orbital decay, I expect to see a long, wide debris field of the shredded stuff, possibly as much as 600km long and 20km or so wide. Followed by the heavy bits impacting in an ellipse maybe 10km wide by 30km long at the end of the path. This heavy impact field will experience many hundreds of impacts, each capable of digging itself well into the ground but not making actual craters of impact. Velocity at impact high subsonic, maybe 800km/h or so and each chunk massing a few hundred kg? Possibly a few heavier but no faster impacts from the big structural beams, engines, or any other dense objects. One possibility: Your vessel is *designed* to reenter. If the design is good enough, that might include *passive* stability sufficient to stabilize it! In this case the debris scenario is all out the window. Your ship will reenter, "glide" down at a shallow hypersonic path, and impact the ground while still at high supersonic speed. In this case, better not live in the city where it lands, neither the city nor the ship will be recognizable afterwards. [Answer] # It's not the fall you should be worried about, it's the stop at the end Your ship is designed for atmospheric flight, which suggests that it's some kind of aerodynamic space plane. If it's designed carefully, it could theoretically be built to survive an unguided trip through the atmosphere. The aerodynamics of the ship could be designed so the gradually increasing atmospheric force would guide it into a certain position that maximizes survivability. Also, if you have the technology to build such a massive ship, you probably have the technology to create a massive heat shield. Even if you used the technology available in the 1980s for the Space Shuttle (and just a little hand waving), you could come up with a scenario where reentering in one piece is possible. The problem is going to be the landing. At the risk of stating the obvious, one million tonnes is heavy. Even if the vehicle slows itself through clever design and survives reentry, you're going to have a huge amount of mass hitting the earth. I suggest playing with [this calculator](https://impact.ese.ic.ac.uk/ImpactEarth/ImpactEffects/) to estimate the impact force. Plugging in some dummy numbers suggests your steel ship splats and buries itself in a big hole. I don't think you're going to have much left to explore. If you want debris that's explorable, you might actually want the ship to break up in reentry. Maybe the designers built certain compartments with emergencies in mind. For example, the bridge may have been surrounded by armor, like how the A-10's cockpit is surrounded by a "[titanium bathtub](https://www.cradleofaviation.org/history/history/aircraft/a-10_survivability.html)" to protect the pilot. That way the commanders would survive a meteorite impact or enemy attack that would rupture the hull and depressurize parts of the ship. So as the ship passed through the atmosphere, it would break into many pieces, with the armored bridge surviving in one piece. Maybe the builders planned for this scenario and added parachutes that automatically deploy in the event of reentry. That would give you a large compartment to explore after the ship crashed to earth. *EDIT: Changed "crater" to "hole" and adjusted other wording per comments from Keith Morrison.* [Answer] **IF** the ship is aerodynamically stable, both during the hypersonic and supersonic parts of reentry, and after atmospheric drag slows it to subsonic speeds (think Apollo or Crew Dragon), then it'll be mostly intact when it hits the ground -- perhaps completely intact, unless it depends on retracting fragile parts like antennae and solar panels to protect them during atmospheric flight. Do note that, per the question, this ship is only about 1/3 the density of water; this is more comparable to an oceangoing freighter (running empty) than a bullet or meteoroid. Unfortunately, when a ship built the way you describe does hit the ground, it'll be ugly. No pilot to slow down at the last moment, no one to extend landing gear or legs -- the result will be a crater. Not the kind of crater you'd get from a meteoric impact, of course -- you're talking a few hundred meters per second (even a ship built as you describe is mostly empty space, after all) rather than several kilometers per second. What you'll get as far as ground effects is much like what you'd see when a disarmed bomb is dropped from an aircraft -- only multiplied by thousands, and quite likely modified by running out of soil depth so bedrock is involved. Think small strip mine -- and inside the crater, plus scattered downrange over a debris field of *at least* several hundred meters radius, will be ship parts and contents. In the end, it'll look much like an oceangoing freighter or liner had crashed at airliner speeds. There will be a lot of recognizable (though probably not reusable) ship parts, a lot of twisted scrap, and a few small or very durable items (purser's safe, for instance, or a passenger's shaving kit) will be nearly intact -- the uppermost superstructure (i.e. the part traveling last when it strikes) will be the most intact, as the lower structure will have absorbed impact energy like the crumple zones in a modern car. Of course, this depends on the shape of the ship. If it's shaped like *Nostromo*, other answers ("it'll tumble and break up at high altitude") will apply. If it's shaped to reenter with minimal propulsion, however, and more like a "capsule" than a spaceplane, this is how its likely to occur. [Answer] **It might land almost intact, definitely recognizable as a ship** Have you seen how slowly the Spacex Starship glides down? If it wasn't fuelled and ready to explode when it's fuel tanks rupture I think it would crash mostly intact, albeit folded up. Look at how recognizable some of the wreckage is (although this is after lighting its engines and at least halving its freefall speed): [![enter image description here](https://i.stack.imgur.com/XI75s.jpg)](https://i.stack.imgur.com/XI75s.jpg) At 120tons dry mass and around 30tons of fuel the density of the nearly empty Spacex Starship falling down is 160kg/m^3. The velocity of free falling objects is actually determined by their surface area, but as long as your ship isn't built like a spear, then density will at least give a good ballpark figure. Plugging the numbers for your ship, it's 300kg/m^3. You say you don't mind changing that by a factor of 10, so halve your mass or double your volume, or make it a huge flat and stable pancake. The classic space saucer shape should work amazing! Especially since it's also conductive to being stable and presenting a huge rounded surface to survive re-entry; like a scaled up version of today's capsules. [Answer] As has already been mentioned, you're going to splash. What you have to do is control the splash. Other answers have discussed passive stability on a reentry glide path. Now we need to consider how the designers could have intended a crew to survive the sudden stop at the bottom. After all, any ship designed to go into a planetary orbit has a risk of a rapid unscheduled landing on the planet. Once upon a time, cars were steel boxes such as the ship you describe, and people died in what are now considered entirely survivable collisions. Nowadays we design the car to sacrifice itself to protect the occupants. Your passive stability puts the crew quarters at the back. The engines have been jettisoned to prevent an explosion killing the crew. Everything else about the ship is crumple zone. * The crew have crash pods * The crew quarters are crash pods * The crew have escape pods * The crew quarters are an escape pod As a designer I'd choose the last, for a story perhaps the second is best as you want to see sufficient destroyed ship and sufficient surviving ship. This ship isn't an unsinkable Titanic, it's a modern family car designed to protect the crew at all costs. [Answer] The ship could land generally intact, with proper foresight in its "heavily designed" plans. (In other words, I read Separatrix's answer and figured out how to control the splash.) Other answers have already addressed a spaceplane / lifting body shape for passive stability. All that's left is the last few hundred kph before impact. Given the assumption that there is no crew, no computer control, just passive systems, the solution to a slow landing is mechanically actuated parachutes. A purely mechanical accelerometer detects when the ship goes through a passive aerobraking sequence, and at the proper point releases a drogue chute. A simple pressure-based system (I'm thinking something like a plug door) ensures that this release takes place only in an atmosphere. Then the drogue chute pulls out the main chute, and a less-than-crash landing ensues. Much like the Apollo craft had 3 chutes and only needed 2 for a safe splashdown, this ship would be built with N independent emergency parachutes, where some number less than N will ensure a less-than-crash landing on Earth. This system requires neither electronic computers nor active crew. It was designed as a final layer of fail-safe for an incapacitated crew to make it to the ground. ]
[Question] [ It's well established that the [human body](http://www.space.com/23017-weightlessness.html) does not do [well in zero gravity](http://science.nasa.gov/science-news/science-at-nasa/2001/ast02aug_1/). Symptoms such as fluid loss, muscle atrophy, bone mass loss are well known. Less well known problems extend to such mundane activities as urinating. Astronauts on space walks need to be reminded to urinate because their bladders can only tell "fullness" with the help of gravity. Related to [this question](https://worldbuilding.stackexchange.com/questions/3781/how-would-the-human-body-develop-under-a-different-gravity) about how a human body would adapt to zero gravity. I'm not adapting to, I'm designing *for* zero gravity. How would you design a humanoid body to operate in zero gravity? [Answer] Humanoid (and every other tetrapod on the planet) forms evolved expecting gravity. If you try to take the basic concepts (skeleton, limbs with joints that only bend one way) and rework for a zero gravity environment you will not produce anything useful. Since you want to start from scratch, look at existing microgravity environments, and then look at Disney to anthropomorphicise the results. End result will be something like a 4-limbed octopus, with bones remaining only in the ribcage, mouth and skull ( and even that's optional, I'm thinking that the brain is worth protecting ). If I am a truly zero-g creature I would want better (and longer) grasping appendages, suckers would be very useful here. I would not want any directional limitations on said appendages. I would also want panoramic vision, which means we can toss the human head concept right out the airlock. Also need an internal method of propulsion so the being doesn't get "stuck" in the middle of a chamber. This means wings of some sort, or jet propulsion like a cephalopod's hyponome. Etcetera, etcetera. In conclusion, redesigning a humanoid for zero g is going to give you a rather poorly adapted creature - you may as well stay with the stock model and just tweak the biochemistry a bit to deal with the known problems. [Answer] I'm going to assume you want to retain the basic human form. You want the body to gain muscle mass at the drop of a hat, without overdeveloping it either. Muscle mass is part of what helps humans avoid energy, but you need very little effort even to lift huge weights in space - a touch is all it takes to move literally tons (2000 pounds) of mass. If they're not going to spend hours and hours of their productive day doing zero-G workouts, they need to gain muscle mass in response to extremely minor exertions. Such easy gain of muscle would be, wasteful and dangerous if food ever runs short, though. The heart is a muscle, and that weakens in space, too, meaning that without ensuring that it gains muscle mass, heart problems that were minor, or even negligible on earth, might become critical. We don't know, but the loss of muscle mass might even be an eventual death sentence for the heart. Next, bone density. Bones lose mass in space. Of course, you're not using them to walk on, but that doesn't reduce the potential stresses a bone might be required to support, especially in an environment where it takes very little force to move you at high speeds. Spinal development in zero G hasn't been studied in humans because nobody think's it's worth the risk (or wants to be known as the country that risked) screwing a child up for life in the name of science. However, it's known to be related to the stresses a human grows up under. Bad posture can deform the spine over time, so it follows that no gravity can cause the spine to grow malformed. We don't know this, but you will want some controls in place to ensure that the body grows to the proper form without gravitational stresses, especially if you ever want them to walk on a planet. There are a lot of other unknowns. Astronauts have just not spent a lot of time in space - if they do, because of the muscle loss and bone loss, they just can't walk on earth anymore. Nobody is willing to abandon a human to space forever, just for science. However, a surprising number of animals have been bred in space, and returned to earth. Being gestated in zero G and returning to G causes serious issues - not knowing up from down, not being able to orient themselves properly, in everything from rats to jellyfish to snails. However, it seems that in rats the inner ear becomes MORE sensetive from being gestated in space, not less - it is exposed not just to downward pull, but constant unexpected yawing and rolling. Therefore, space bred rats rapidly recovered their lost ability to balance, and adapted to gravity. I haven't found any long-term studies of animals raised from childhood to adulthood in zero-G, but I didn't look too long. Maybe you'll have better luck. As to changes to the human form . . . I can't see a lot of people wanting to. It sounds cool, but when it comes down to it, humans find humans attractive, and nobody wants to be engineered to be unattractive. Beyond that, our brains are built to handle two arms and two legs - messing with our brains until handling tentacles is natural would go so far that I would suggest it represents a divergence of species - they would be no longer human. Going back to our roots might be easier - feet that are better for gripping and prehensile tails might be handy in space, might not mess with the 'human' aesthetic so much, and are things that our brains already were once hardwired to handle, and might handle again easily. [Answer] Building a bit on user12247's answer, I will suggest there are two environments that need to be looked at, requiring two rather different solutions: 1. A creature living in 0g volumes such as space stations. Here things like suction cups on the limbs and so on would work rather well. Wings, flaps between the limbs that can work as wings or some sort of jet propulsion system will also be quite useful in getting around. If we are going to play with genetic engineering on that scale, maybe spinnerets like spiders would also be useful, you could stick a string to a wall or surface and cast off, but pull yourself back if you miscalculated somehow. 2. A creature living in the vacuum of space. Here we need an armoured and protected volume for the biological systems. The creature would have a heavy skin like an elephant (human skin actually survives exposure to vacuum rather well, but for prolonged exposure, we want more protection), or alternatively protection in the form of an exoskeleton like an insect (we need to take growth and shedding old exoskeletons into account if we go this way), or perhaps armoured plates like a turtle's shell or some dinosaurs (with the problem of a mass penalty). You would want to reduce if not eliminate the expulsion of matter into space, so the creature would have to be symbiotic, with what could best be described as a hyperplant growing from the creature, being nourished by the waste products and feeding back oxygen, carbohydrates, sugars and proteins into the bloodstream. We might possibly want other symbionts in the "ecosystem" to do things like process asteroidal material to make up deficits in the recycling and "top off" raw materials. The circulation of fluids in the hyperplant would also serve as part of the temperature control mechanism for the symbiotic relationship. To be really exotic, the hyperplant could have reflective leaves, or electrically charged "vines" to provide solar energy and propulsion for the creature in free space; a built in solar or electrostatic sail. A spinneret might be useful, but the potential loss of mass unless it can be recovered and recycled would have to be carefully considered. When at rest, the creature would be "starfished" out to provide the maximum surface area for the hyperplant, while being able to "reel in or otherwise retract the plant part of the symbiont when needing to do work with the limbs. ]
[Question] [ In my world, I would like to have a certain configuration and I wonder if it's plausible or not. There is a continent with a climate similar to the Amazonian basin, covered by a very dense forest. This climate covers much of the continent. It is inhabited by natives tribal societies scattered around. The rest is made of different type of tropical and subtropical forests. I would like the continent to stay relatively unsettled. The problem is that it's part of a bigger world. His close neighbour is a large continent with many civilizations. The most advanced of these countries have a level of advancement similar to 15th century Europe. These civilizations trade with other continents by the sea and some of the trading routes goes along the coast of the jungle continent. However, these people live in temperate climates and are not accustomed to the hot/humid weather. I guess they might establish some trading ports like the Europeans did when they began expansion in Africa, India and Asia but not much more. * Considering that some areas on the east coast are [drier](http://en.wikipedia.org/wiki/Tropical_and_subtropical_dry_broadleaf_forests). They could be easier to settle. * The area is somewhere between 1,5 to 2 million sq km. * The continent has many unique species not found anywhere else because it was separated form the other landmasses long ago. It's different but there is nothing that is considered more dangerous than our own Amazon. **Is it plausible that this continent is still mostly unsettled and still populated by hunter-gatherers?** [Answer] 1 word: **Disease**. Disease is your friend in this instance. In the real world, the prevalence of disease in the temperate climates is, well, tempered by the arrival of winter every year, which kills lots of carrying vectors of disease. The tropical parts of the world have no such protection, and, since humans have been living in tropical areas such as Africa for hundreds of thousands of years, local diseases are particularly well adapted to infect humans. For sailors and would be colonizers from Europe, unaccustomed to the local disease load, this was almost certain death. Crew losses due to disease during the 16th century ranged up to [about half of the crew](http://en.wikipedia.org/wiki/Portuguese_India_Armadas#Losses). (!) Every fresh boatload of would-be colonizers would be struck just as hard. Europe did not make any serious inroads into Tropical Africa until after Pasteur's germ theory of disease laid the basis for thinking scientifically about combating disease. Even the survivors would be left weakened and at risk for the next bout of disease. [Answer] Its plausible, depending on your setting. As @SerbanTanasa pointed out, disease is a terrible thing. But... Another solution to make it harder to colonize would be to increase the danger-levels of the area, in a manner of speaking. What if the continent were like fantasy-Australia, basically smothered in dangerous creatures and feral wildlife? The poor disease-stricken sailors would have to fend off these wild creatures while being undermanned and underarmed. Even worse would be to make these creatures vectors for the aforementioned diseases! Just make sure you leave a bit of meat on the bone for those poor playe- I mean sailors. Otherwise they might just give up entirely. [Answer] Additionally to other answers providing difficults to the arrival of the colonizer or the stablishment of settlements, consider providing no them with no incentives to colonize: * colonizers find no valuable minerals. * the crops from their home don't adapt to the soil, native crops are wild and a bad for being cultivated. * difficult fisheries, catch is not appreciated by the colonizers. * In the wet climate, the animal furs are difficult to treat and most of them get spoiled. * Another possibility would be religion/superstition. Maybe the native wear colors and/or ornaments that, by pure luck1, to the colonizers are too similar to items that are tabu or related to evil gods. Of course, you do not need to make all the continent without minerals, fertile soil, etc., but only a considerable chunk near the shores. 1: Or maybe not by luck, it could be a reminiscence of a long forgotten "first contact". [Answer] In addition to disease, and crazy bugs, you might consider **Geographical Constraints** as well. If your continent is ringed by mountains, with the only gaps being violent discharges of the rivers (not smooth sailing), this could be prohibitive. One argument against this is the rain-shadow effect, so you'll have to devise a weather pattern that is either recycling itself over the continent (not likely), or other mechanisms, which do exist. Perhaps the mountains are just steep, but low (100m) cliffs, etc. There would be little interest from the merchants to try to use resources from the interior of the continent, if it's a pain in the butt to extract them and haul them over low, steep mountains/cliffs or out via very turbulent river waters - maybe even waterfalls. [Answer] I'd suggest hazardous plants and creatures could work well here in addition to the other answers. If virtually every spider can kill you. Fruit with really subtle differences might taste delicious, or might kill you with one bite, snakes that look like hanging creepers, etc. The natives know what to avoid. What to eat, how and where to walk, what areas to avoid, etc. Intruders without a native guide (or even with them since they have a history of assuming they know better and ignoring the guide) would quickly perish to these hazards that would seem obvious to a native who has grown up around them and may not even think to warn them. "What do you mean he walked through there? Those are clearly Panam rushes. Look at the serrations and purple markings near the root. They scratched him? We've got 30 minutes to amputate both his legs or he's almost certainly going to die." ]
[Question] [ I have a character that has the ability to slap people into next week (give or take a few days). The character has two people with them trying not to get caught by the government. Assume they are both trained in the killing and maiming arts (shooting, punching, stabbing, etc). This character can also kind of control how far in the future they slap people. A tap could be a few hours, and a big *WHAP* could be two weeks. So now you know the time traveling team, let's talk about the government. Assume they have at their disposal; local PDs, HPs, state BIs, SWAT teams, plus agents from the FBI, CIA, HS, and other stuff. So, any government agency. This might seem a bit one sided, BUT the time traveling team has a hacker friend who was able to erase them off the grid and get them randomizing IDs/credit cards/whatever (they can't be tracked via credit cards, cars, phones, whatever) AND they get early warnings of whenever the government finds them (a few hours to two days) AND facial recognition doesn't work on them (but if some random FBI agent was watching the Walmart checkout, they would see them). Basically, the government has to see you physically to be able to know where you are. Some other details: * the slapper can't slap themselves forward in time * whenever slapped forward in time, the slapped don't feel anything, the scene just changes to whatever it is when they come back from no-time * the slapped reappear within 10 feet of the slapper after getting slapped in time, with all clothes, guns, stuff they were holding, etc * the government is trying to keep the public from finding out, but can do shootouts in the middle of the streets if they come up with a good cover story * assume modern day technology, cultures, buildings, whatever So what tracking methods or whatever would the government use to find and capture these three on the time travel team? [Answer] Before facial recognition, the CIA/FBI and other ops departments compiled teams of analysts who would hunt through all sorts of data tracking past and present information from phone records to shopping habits to street cameras to personnel reports, to create a profile of their target and anticipate movement, then engage field teams to cover anticipated intersections. If you want to provide tension for your team, think of the vulnerabilities they most fear and assume the government has thought of it and will exploit it. Also assume the govt. will eventually catch on to hacker activity/inside info and will employ red herrings to pressure the team into acting in predictable ways. Since the goal would be to prevent slapping, multiple snipers at range with a ground team ready to collect the bodies, or a ground team designed to force them into a killbox where a sniper or team of snipers can get a clear shot. If capturing is the goal, then tranquilizers would be used ahead of bullets. The exact power almost doesn't matter since any physical contact can potentially cause a time shift, BUT since the slapper can't slap themselves forward and the slapped will reappear within 10 feet and the authorities know this, they might elect to swarm the slapper using basic crowd control methods to restrict movement. Even if a few get bopped into the future, they'll show up again within striking distance, fully armed, or at the very least they could appear with tracking devices, giving the feds a solid lead on the slapper's location. There's a lot of ambiguity in this scenario and a lot of opportunity to create tension, but hopefully this gives you a few ideas. [Answer] The slapper can only send his friends to the future, and cannot slap himself. Plus, the slapped people will appear next to the slapper. Thus, the government only needs to capture the slapper, put him somewhere safe in the middle of nowhere (Siberia? A jail surrounded by a desert?) and wait up for to weeks for his friends to appear. The catch here is that you better do that before their friends magically appear near your handcuffed slapper shooting the near officers. And the fact that the government probably don't really know how it works (although they try to keep it secret while assuming they know everything on how it works). One approach would be to slap his friends so they appear in the middle of the night, when the capturers don't expect them to materialize. However, that might happend to be at a cell, so even those highly trained assassins could end up trapped. Slapping them shortly after would find the police less prepared (e.g. while transporting him in a police car), but it can also be less "discreet" (e.g. two guys with riffles appeared from nowhere in the middle of the highway and started shooting a police car that was driving away). Now, if the slapper could forward *himself*, of if he could slap people to the past, it would be a much harder challenge. [Answer] ### Give the police something better to do than chase you. The best capture strategy for you is to make them not care about you. Your strategy is to make them stop having a strategy for you Walk into a crowded nightclub, start dancing, and in the middle of the dance floor, when it's dark and the music is loud, nobodies paying attention and everyone has their hands up to the groove, discreetly slap some random very attractive person. Someone whod look real nice on a "missing persons" poster. Keep dancing. Leave the venue later, very clearly by yourself, so nobody reports you as suspicious. Good thing you dont get identified on CCTV so facial recognition cant spot any frequent dancers. Then exactly a week later (also at night), take a tiny single seater ultralight aircraft out for a flight over open water. Fly just below where you need supplemental oxygen, above clouds if possible. Do your take offs on camera so if anyone gets suspicious they can see your tiny plane wont hold a body. They respawn into existence 3 meters away from you, and fall to their deaths. Through the clouds. Bodies wont be found immediately, most never will. The police will be questioning their family / lovers/ friends using most of their resources. The few that do rock up will be mutilated by the fall, and most bodies who fall this far into ocean are found naked, police will assume water has washed away DNA evidence. Flail injuries from the fall will look like evidence of a beating. Police will be so busy trying to find the serial "rapist" who abducted some of these missing people out the back door of a crowded nightclub without hundreds of witnesses seeing, killed them, and covered his tracks by dumping the bodies off a cliff (to explain the impact injuries found at autopsy, if they identify them as that) into the ocean that they'll forget about the myth of the face slapping trio. And if they do figure out they were dropped from a plane, they won't figure out timeline cause inexact estimates of time in water, but even if they do, you have video showing your plane was too small to hold more than one person. Maybe even video yourself the whole flight just for the ultimate alibi. Can also fly over a volcano, a desert, dense bushland, shark infested waters, etc. Or even just different police jurisdictions. [Answer] Assuming the Slapper would slap his teammates to a safer time and escape as a single person and that he might be able to control his ability to the point of millisecond slapping people 10ft away, He would be nigh impossible for less than 3 people to corral. If he had his friends you would need 3 people for each. Scenario 1 less than 3 people per person: Our resident slapper slaps the first person he comes across that's hostile and is now in a 1v1 scenario which is ideal for him. Scenario 2 at least 3 people per person: Slapper is up against 3 agents. He slaps one and then they know which target has the ability and can safely detain the other 2 easily. The slapper is then surrounded and without support. Assuming he only fights the 3 he is up against, slaps the first and is still up against 2 who can keep their distance and train weapons on him. You have one backup who can keep him covered while his partner restrains the slapper. In conclusion, you would need at least a team of 9 to contain the slapper and his comrades. Tracking would be much easier. Simply giving out the pictures to the wanted list would yield more than enough info to keep him tracked. At that point, its the usual waiting game and is no different from our world. The true difference is the capture methods needed. ]
[Question] [ A few years ago, an old map started circulating around the internet from 1850 with a proposed [Western District of Columbia](https://bigthink.com/strange-maps/492-western-dc-haunt-of-superman-simpsons-and-presidents) located in western Kentucky, across from the real Illinois town, named in a bout of wishful thinking, Metropolis, Illinois. I'm trying to create an alternate history scenario where this or something similar actually happened, **what should my point of departure be?** Here are the requirements: 1. Like Washington, DC, the new capital should straddle the border between two states, either along the Mississippi River (between Missouri and Illinois) or the Ohio River (between Kentucky and Illinois or Kentucky and Indiana). 2. As I mentioned in the title, this should happen before 1900. I want the capital to sit in the Midwest long enough to create a government bureaucracy in the area as the 20th century progresses. 3. The US should stay mostly or completely intact as in our real timeline. For instance, I do NOT want the capital to be moved as a result of the Confederacy winning the Civil War or the British retaining the Atlantic coast in the American Revolution. 4. Bonus points for a new city created to be the capital, like Washington, DC, but I'll also accept proposals to move the capital to an existing large city like St. Louis. In real history, there were a few semi-serious proposals to move the capital that I've found: **1814** - When the British burned down Washington, there was some discussion of moving the capital elsewhere (Philadelphia most likely), but Southern representatives wanted to keep the capital adjacent to a state where slavery was legal and argued that moving after a defeat would be a sign of weakness, so DC was rebuilt. **1846** - When a portion the District of Columbia was retroceded to Virginia, Senator William Allen of Ohio briefly argued that the capital ought to be moved west, but no legislation came from this. **1861** - Though there was never an official call for the removal of the capital during the Civil War, it is worth noting the tenuous position of Washington, DC. Virginia, on one side, was in open rebellion and home of the Confederacy's capital in Richmond. Maryland, on the other, though generally sympathetic to the union, was a slave state and martial law was enacted to keep it from seceding. The fighting came within miles of DC, and President Lincoln actually came under fire at one point. **1868** - Probably the closest any legislation came to moving the capital, a [vote was held in the House of Representatives on moving the capital to the "Valley of the Mississippi"](https://books.google.com/books?id=XElIAAAAYAAJ&pg=RA1-PA225&lpg=RA1-PA225&dq=herbert+paine+%E2%80%9CValley+of+the+Mississippi%E2%80%9D&source=bl&ots=dhUEt7tjHr&sig=ACfU3U0jhIzp4KxUSczQC8pCJ_SGrhnS0A&hl=en&sa=X&ved=2ahUKEwiJwOOyjp_jAhXRAp0JHUetBxoQ6AEwAHoECAkQAQ#v=onepage&q=herbert%20paine%20%E2%80%9CValley%20of%20the%20Mississippi%E2%80%9D&f=false), and the motion failed by only 20 votes. The following year, several western states sent official delegations to a convention to [discuss moving the capital to St. Louis](https://untappedcities.com/2016/04/19/st-louis-missouri-capital-of-the-united-states/), but it seems no action was taken following the convention. The movement pretty much died by 1871 when President Grant was able to convince Congress to appropriate money for the improvement of Washington, DC. I feel like sometime between 1846 and 1870 is the most plausible time to make this happen, can one of these be manipulated realistically to move the capital? [Answer] ### Confederate Maryland You don't need the Confederacy to win the Civil War. Just switch around some of the states. In particular, if Maryland joined the Confederacy, it would have been difficult to keep the capital in Washington, DC, as the portion of the District of Columbia containing the White House and other government buildings was ceded from Maryland. This is especially so if Virginia, or at least the eastern portion, was also in the Confederacy, as that would make the capital entirely surrounded by the Confederacy. This is reasonable as Maryland was a slave state. So in many ways, it would have been more natural for it to join the Confederacy. A side issue is that this would have given post-war Maryland different representation, as it would have been part of Southern reconstruction. That might have been just enough to change the balance of the 1868 vote. ### Destroyed DC The capital could have been destroyed in the Civil War. So after the Civil War, if they don't rebuild, they might eventually put the capital somewhere more centrally located. ### No President Johnson If Abraham Lincoln had survived his assassination attempt, there might have been less reconciliation with the South. Alternately, if Andrew Johnson had died in his assassination attempt, there might have been less reconciliation with the South. Having Johnson succeed Lincoln led to a much more accommodating government. ### Union Lee Lincoln offered Robert E. Lee command of the Union armies. What if he'd taken it? There would have been less confusion at the top of the Union command. Lee might have won the war prior to the 1864 election. Andrew Johnson might never have been vice-president much less president. Ulysses S. Grant might never have become famous. As the winning general, it would have been Lee who would have been president. Lee might not have felt as strongly about keeping the capital in Maryland. [Answer] **Americans do not like powerful big cities as their capitals.** Here is an American idiosyncrasy I have never seen discussed. Americans like their capital cities to be little cities, with no particular power or claim to fame except that city is the capital. In England the capital city is London, the biggest. Same for France, same for Italy. In the US it is not Philadelphia, or NYC, or Boston: it is little DC. That is echoed in every American state except Georgia: the capital is not the biggest city, but some smaller central city. I suspect this is because of US-style democracy and a tug of war between cities which are economically powerful and rural areas, which are big and concerned about being relegated to second class. This remains a powerful dynamic in the US as seen in our last presidential election. The capital can move when the West coast and Midwest are big enough to demand their places at the table, not the kid table in the next room. I think this should be after 1900; maybe part of the Return to Normalcy following WW1. Chicago and St Louis are mighty and the West coast is up and coming. They want to spread the wealth. The US has a new way of thinking and the interior and other coasts have gained new respect from the East. It is a new century and a good time for a change. It makes sense that a capital should be a smaller city, central and located near the Mississippi - Metropolis, KY is on the Ohio and a straight shot along that to the Mississippi. I like too the idea that maybe this happened in a timeline when the civil war was not so destructive and the South not so utterly crushed. Maybe the Union buys all the slaves and frees them, and the two sites agree to make laws banning the sale or purchase of slaves. There will be fewer hard feelings after an amicable settlement and a generation later it will be easier to cooperate. [Answer] ## Tweak the Civil War The Confederacy was unlikely to succeed in the Civil War due to the North's advantages and world opinion being against them, but they could have likely stretched the war out longer. Perhaps have Lee's confidence be reduced after Antietam such that he fights more conservatively in his Gettysburg Campaign turning it into a protracted stalemate as opposed to a dramatic defeat. The war would likely go on for an extra year or two with the Confederate army looting Union lands to keep supplied. With the Confederate army north of Washington DC, politicians relocate to a less precarious position in Philadelphia. This stalemate also buys more time for ambassadors to try and secure European intervention on behalf of the Confederates; worrying the Union. Eventually, appeals for foreign aid will fail and the North will bring its industrial might and numbers advantage to bare, forcing a Confederate surrender. However, the extra year of fighting in this reality would have more greatly soured the North's disposition towards the South, giving more progressive and militant Republicans the leverage they need to combat Southern Redeemers during Reconstruction. In the short term this would likely lead to the KKK targeting the federal government in a greater capacity than it did historically. The combination of increased Northern resentment, Washington DC's precarious position both from Southern aggression and European intervention, a precedent of abandoning it, its proximity to inflamed sectarian violence, and increased progressive leverage all could contribute to a campaign to move the capital North and inland. This would make the capital more defensible, act as a political spite to the South, and could be used as a tool to help encourage expansion into the Free-Soil Territories. [Answer] **Why create Washington in the first place?** Compromise of 1790 resulted in setting the capital in Washington D.C. as a bargaining chip for Hamilton's idea of national debt assumption. As the Congress was in the deadlock, it is not hard to imagine a different scenario where South doesn't get the capital and Hamilton's plan fails. This could lead to major financial problems for U.S., but does sound probable. <https://en.wikipedia.org/wiki/Compromise_of_1790> ]
[Question] [ [![enter image description here](https://i.stack.imgur.com/5zQEH.jpg)](https://i.stack.imgur.com/5zQEH.jpg) I'm having trouble figuring out the various biomes for my planet. I have extensively read the [post](https://worldbuilding.stackexchange.com/questions/1353) on "Creating a realistic world map - Currents, Precipitation and Climate". But to be honest, I'm hung up on my map projection and getting the latitudes correct. My mind just can't seem to get over the hurdle that the land masses are distorted and how to correct for it. Any help would be appreciated. [Answer] Getting all the way to biomes is a multi-step process, at least in my experience. You can't just start with a simple map of the continents and expect to skip straight to biomes and climates. In describing the various steps of generating a fictional climate map (be warned that you can't really do them out of order), I'll be assuming something generally Earth-like that spins the same way; reversing the spin would reverse directions for winds and ocean currents, and going too far from Earth-like conditions (10-hour day, excessive heat, etc.) would probably invalidate most of these guidelines. I'm also ignoring realistic mountain ranges here; plate tectonics would be a good idea to look into, but not strictly relevant for climates except over a geological scale. **Elevation** You need to start with a respectable altitude map; if you're doing this on paper, expect to print out a lot of copies, because this is your baseline for everything else. At minimum you need to be able to easily divide these categories, probably by color on the map: deep ocean, shallow ocean (<300m deep), lowlands (<1000m), highlands/plateaus/etc. (~1000-2000m), and mountains (anything higher). More detail is better (divisions every 1000m of elevation on land would be a good idea) so you can get more accurate results, but not strictly necessary. **Ocean Currents** Ocean currents generally follow some straightforward rules, but [this example](https://www.cartographersguild.com/attachment.php?attachmentid=97136&d=1498925035) of Earth's currents will likely be useful. For this, you're mostly going to be using latitude lines, so make sure your map has those on it. You start with two currents flowing westward near the equator (around 5N/5S); if you decide to have your planet spin in the opposite direction of Earth, this is one of the things that will reverse direction. Whenever those currents hit a major landmass, they will be deflected north or south as appropriate towards the poles. They will generally go more or less straight at first, but at around 35-45N/S they will be deflected eastward by wind patterns; if they run into a landmass jutting out before then (see India), they will bend sooner. Follow them eastward on that latitude line (around 45N/S generally) until they hit land; generally, the current will split at that point into north and south currents (one going to the equator, the other heading to the relevant pole). There will be polar currents as well, flowing eastward at around the 60N/S lines. The general rule with ocean currents is that they should always make closed patterns, typically circles; if you have a current that just stops at land with nothing continuing it, you've probably made a mistake. You might have to draw in some additional currents to have it make sense. Currents tend to run in force only through deep water; a continental shelf (which tends to be shallow for ocean water) might as well be the continent proper. It's important to separate the currents by type: warm, neutral, and cold. Basically, currents heading towards the poles are warm, while currents heading back to the equator are cold, and everything else is neutral. It's entirely plausible to have a warm current at 70N/S (see the coast of Norway) and a cold current at 10N/S (see western Africa). A quick tip: the western coast of a continent tends to have a cold current when between 10-45N/S, but a warm current from 45-60N/S (reverse this for the eastern coast). **Air Pressure Systems** This one is somewhat harder. You're going to need two different maps here to cover summer and winter (I'm going to refer to this as northern summer/northern winter, because the southern hemisphere will be in opposite seasons, but you can call them the hot and cold seasons or whatever else suits you), because air temperature has a significant impact on these matters. Smaller islands are effectively negligible in this section; overland refers to large continents, so something like Hawaii or Iceland has no meaningful impact. You need to chart the [ITCZ](https://en.wikipedia.org/wiki/Intertropical_Convergence_Zone) line first. This is near the tropics and is a consistent low-pressure zone, but it does move slightly over the seasons. Draw a line at about 10N/S (whichever hemisphere is in summer) across the ocean eastward until you hit land. Your line is going to get pulled slightly towards the pole by continents, most noticeably on the eastern coast, but not too far; the strength of the effect depends on the landmass, and if the ITCZ hits the 20N/S line, either you've made a mistake or your map has something with the general size and placement of Asia. If you go past the tropic lines (23.5N/S), that's a problem unless you have a giant Pangaea in one hemisphere. Note that this assumes an axial tilt equal to Earth (23.5 degrees); adjust the axial tilt, and the suggested latitudes will need to shift appropriately. High-pressure systems are likely to form over the sea at around 30N/S in winter, generally on the eastern side of an ocean (near the western coast of a continent); in summer, move them to 35N/S. Overland, you only get high-pressure zones in winter; as a rule, a larger continent means higher pressure and a larger high-pressure zone (Asia has a monstrous zone in January). Low-pressure systems in oceans tend to form around 55N/S in winter, and at 60-65N/S in summer; these will span most of the ocean at the relevant latitudes. Overland, they only form in summer; draw them mostly closer to the eastern coast, and once again a larger landmass reflects a larger low-pressure zone. **Winds** I hope you appreciate circles because this section will have lots of them. Once again (like most of the later sections), you're going to need separate maps for the northern summer/winter. Generally, wind currents flow from high to low-pressure zones, subject to the interference of mountain ranges and the like. They flow in a clockwise direction out of high-pressure zones in the south, but a counter-clockwise direction out of northern high-pressure areas: [this diagram](https://www.cartographersguild.com/attachment.php?attachmentid=76626&d=1444248370) might be helpful. Low-pressure zones reverse this; northern zones generally have winds entering in a clockwise fashion, or counter-clockwise in the southern hemisphere. High pressure zones will blow winds out in all directions, so you're going to be drawing lots and lots of arrows. Anything going towards the poles (>45N/S) will quickly shift direction eastward due to the westerlies. Winds blowing towards the equator will gradually be blown westward as they move towards the equator; these are the trade winds. Low pressure zones (including the ITCZ) will act like magnets, drawing in nearby winds, but it's quite possible to have wind passing between high and low pressure zones without entering either one if the rotation mentioned above results in the correct direction; if both zones are sending winds in the same direction, winds in between will likely be following that same direction instead of moving into the low pressure zone. This can also happen if you end up with a mountain range blocking the way, like the Andes. Also make sure to draw the winds (following the clockwise or counter-clockwise rotation as appropriate) even inside the high/low pressure zones. These winds will be weak, however, if the zones are of significant size. **Temperatures** This is a tough one. Again, you'll need summer/winter maps. First, map out some key influences. Ocean currents (warm/neutral/cold) and continental influence are the relevant ones here; if necessary, get an extra pair of maps for these. The current influences are coastal, and affected to some degree by wind; if your wind map has air blowing over the appropriate current type (neutral is essentially a transition, typically around 45N/S, but warm currents in higher latitudes are also likely to qualify as this) onto land, draw the relevant influence a little further into the land. Continental influence tends to fall under high pressure zones in winter, or low pressure zones in the summer. If you have something like Asia, expect its continental influence to be exaggerated near the center. Also, any ice pack situations (see northern Canada and Russia) will be continental as well. For the temperature guides, I'm relying on these images (source is in the credits): [![Latitude Guide](https://i.stack.imgur.com/zoXyP.png)](https://i.stack.imgur.com/zoXyP.png) [![Color Guide](https://i.stack.imgur.com/wQTN6.png)](https://i.stack.imgur.com/wQTN6.png) The latitude guides are a general pointer for temperatures at a given latitude, assuming sea level; temperatures will drop roughly 6C for every 1000m of elevation, so mountains will be significantly colder. The last image is a color guide relating the colors in the latitude guides to the appropriate temperature ranges. Continental plus, essentially, is to be used in a central-Asia type of area, so it's not relevant unless you have large continents with probable ice-packs blocking the north or south. These guides aren't exact (climates being by nature rather inexact when trying to apply what amounts to educated guesswork), so there's a fair bit of fudging involved. Coastal areas tend to have milder temperatures (warmer in winter, cooler in summer), but this doesn't typically apply to inland seas or ice-pack conditions. If you're using the extreme edges of the scale (dark red or purple) in more than very small areas, you'll probably want to do another draft; applied to Earth, this method maps the greatest heat only to small parts of Africa and Australia, whereas the nastiest cold is only in Antarctica or Siberia, or perhaps something like Everest. **A warning here**: this assume Earth conditions. Changing the axial tilt, the solar constant (essentially the relation between average orbital distance and the sun's luminosity), orbital eccentricity, albedo, and so on will have a serious impact on the latitude guide. Figuring out precisely how to adjust the latitude guide to match changes in conditions is probably a matter of educated speculation, but I'll try to give a few pointers. Adjusting the axial tilt will have a greater impact at higher latitudes; a larger tilt translates to greater extremes in temperatures. If solar luminosity or orbital distance changes, that will affect your planet's average temperature. In a non-trivially eccentric orbit (I would think e <= 0.03 would be trivial, but that's just my opinion), orbital distance will not remain effectively fixed, which obviously will affect temperatures and probably require you to make separate latitude guides for the north and south hemispheres as well as for the seasons; you'll also need to place perihelion and aphelion in relation to the seasons. **Precipitation** This one is possibly the single ugliest topic (being the most subject to estimation and interpretation), so you should expect to do multiple drafts before you get this right. Get summer/winter copies of your map ready, and make sure you have the wind and air pressure maps at hand. If your map doesn't have longitude lines, you might want to add them now, because they're a useful distance estimate. This is essentially going to be painting a lot of influences, and then estimating total precipitation based on how many overlap at any given area. Make very sure you pay attention to wind direction; a lot of these factors change drastically if wind is blowing onto shore versus being parallel to it or from land out to the ocean (the former scenario results in more precipitation, while the last one likely means none). Note that a mountain range will, under most circumstances, block any significant rainfall on the other side unless precipitation can come from both sides due to orographic lift (more on this later). Also, inland seas will generally not offer significant material for precipitation, although unusual circumstances might come up. Start with the ITCZ line. This one is a huge influence, because it draws any winds coming from the equator. It's not quite a guarantee of massive rainfall, it must be noted: the Sahara sits under the ITCZ for half the year, yet it's a desert; to my understanding, this is because the Sahara is too hot for any moisture to really precipitate, no matter how much evaporated from the Mediterranean. Still, this is where the great majority of tropical rainforest is going to turn up. Paint a reasonably thick line (around 10 degrees of latitude) over the ITCZ, and expect a lot of rainfall over this area unless you get a mountain range or something like that in the way. Next come some effects from westerlies. This starts at around 30N/S in winter (moving poleward), or around 45N/S in summer, and is mostly present on western coasts. You'll get a fairly strong effect on the coast, but it quickly weakens. Winds can carry the effect a long ways inland if blowing in the correct direction, but rainfall will diminish over distance; for any map with an Asia-like continent, it's likely to end up with a desert near the center. Storm paths are another influence. These are mostly on eastern coasts from 25-50N/S, and are found west of high pressure centers over oceans. These bring a lot of precipitation several degrees of longitude inland if the winds blow directly onshore and still quite a bit even farther inland, but like other influences this one diminishes with distance. As the name suggests, you may want to note these areas as being storm-prone; the best examples of this on Earth are the eastern coast of the U.S.A and the Caribbean, with the hurricanes that so often roll through. Orographic lift, also known as rain shadow, is another crucial point to take note of. If rain-filled winds get blown onto mountains, the clouds will rise. As they rise, they get colder, and the moisture condenses and falls out of the sky: when they descend on the other side, they warm up again, so any moisture left is unlikely to precipitate. The end result is a lot of rain on one side of the high ground but very little on the other. This is what gets you temperate rainforests like southwestern Canada has, and it's also why plateaus like Iran will generally be dry. The greater the elevation change, the stronger the effect; a mountain range will be more significant than a plateau. It is crucial to note that ocean currents may play a role here. If you have a cold current near a high pressure zone, any winds blowing onshore over cold currents are very unlikely to lead to precipitation, even if orographic lift would normally occur. This leads to areas like northwestern Africa, which has almost no actual precipitation. As a general rule, precipitation drops as you move towards the poles; high pressure zones also tend to have reduced precipitation, due to winds rushing out of them instead of into them. Temperatures are notable for certain cases: if you have a sudden rise in temperature, you probably won't get much precipitation. Winds blowing from polar regions are likewise improbable bets for any real precipitation. **Climates** This is what you're ultimately working for, and it's almost anticlimactic that the final step is actually one of the easiest. Take your temperature and precipitation maps (there should be four in all, since you need summer/winter maps for both) and correlate the data at given regions to find your climates; I would recommend the [Koppen climates](https://en.wikipedia.org/wiki/K%C3%B6ppen_climate_classification) for classification. I don't think it necessary to spell out all of those climates in detail here, but be warned that your precipitation map is only an approximation and should be used as such; think of precipitation in terms of low, moderate, high, extreme, etc., rather than in exact measurements. If you've got a tropical region that's drenched in one season and bone-dry in the next, for instance, you probably have a savannah climate. If you're not reaching at least moderate precipitation in either summer or winter, you have steppes or a desert (or tundra, if it's cold enough). **Credits** My information comes in large part from Wikipedia (for general knowledge purposes) and from some excellent tutorials at the Cartographer's Guild: [this one](https://www.cartographersguild.com/showthread.php?t=27118) was of use, and especially [here](https://www.cartographersguild.com/showthread.php?t=27782). The latter tutorial is also where all images came from. [Answer] For a real-world map example to gather information from, such as temperature, precipitation etc, I'd recommend you look at this: [Earth: A Global map of weather conditions](https://earth.nullschool.net/#2017/07/27/1500Z/wind/surface/level/equirectangular/loc=-81.267,-89.733). You can change the projection and other aspects of it, which may be useful as a guide. However, for your specific issue with the latitude, I'd start with plotting the equator, and then splitting both hemispheres into 3. The line made closest to the equator will represent 30 degrees (which is usually where, in an Earth-like world, hot deserts are most likely to form), and the line made closest to the poles will represent 60 degrees (where jet-streams tend to be found). You can also then further split up each section to get more accuracy over latitude - which is more important when placing where your tropics and arctic regions will be - Something that (according to one of [Artifexian's](https://www.youtube.com/channel/UCeh-pJYRZTBJDXMNZeWSUVA) Videos) can be derived from your world's axial tilt. To find the edge of the tropics, place a line at the same number as your axial tilt. to find your polar regions, take the number of your axial tilt away from 90 degrees. Plotting all of this down should help you have a rough guide to figure out where bands of certain climate regions will form. Other aspects such as mountains & landmass size may also have an impact on where certain biomes form, but this is the first step I take whenever I try to figure out where biomes form in my own map-making, so I hope you'll find it useful. [![](https://i.stack.imgur.com/Ot82R.jpg)](https://i.stack.imgur.com/Ot82R.jpg) *(This was the closest image i could find which kinda shows what i describe that you should do. This is slightly different, as in i mark out the tropics and polar regions (as i never got around to putting in other indicators for this map) but never-the-less)* [Answer] Try looking towards real life earth for an example. It also depends on the mass and air pressure, a good example is looking at the carribean and looking at ocean currents and air currents so you can see how warm air looks. The only problem I can think of is the wierd tilt the earth has where we rotate slightly differently than where the sun hits us. TLDR: look at ocean currents and don't be too concerned [Answer] First off is the **temperature distribution of your planet**. On earth, it's hotter around the equator and colder at the poles, though this may not be the case for your planet. This depends on your planets tilt relative to the sun. Once you have that thoroughly established, you can move onto other important factors. Next is ocean currents. These follow the shape of your landmasses and are huge factors that contribute to climate. Here's how Earths currents look: [![earth.currents](https://i.stack.imgur.com/5x3hj.png)](https://i.stack.imgur.com/5x3hj.png) **Currents** will carry temperatures all around the globe, making some beaches cold and others warm, however these temperatures do extend a decent amount inland, and often a regions average temperatures and climate will be related to the temperature of the currents around it. When you get to the societal part of worldbuilding, currents will also establish boating trade routes and the like. **Wind patterns** will also follow ocean currents, bringing temperatures with them as well as storms and weather. If there is a rainy area with a south blowing wind, the rain will be carried to those south places. The next major factor is.. you guessed it, elevation!Hopefully you understand your tectonic plates and their movements well enough, because these decide mountain ranges and other such land forms as well as the **elevation** of an area. Another general rule is that the elevation is lower near the coast and higher inland, but this might change once other factors come into play. Elevation accounts for the obvious: it gets colder the higher you go, like snow on mountain peaks. However, areas with higher elevation are not only cooler, but also receive more precipitation, because the clouds rise higher, causing them to condense and fall as rain (or snow). The last major factor I can think of is **local geography**. A valley might affect the way the wind blows. A mountain will affect precipitation (<https://sciencing.com/do-mountains-affect-precipitation-8691099.html>). Pretty much every geographical factor will affect the climate of that area, but often it is on a very small scale. Although ofc, if you have a giant mountain range or other feature, this will obviously cause a much greater change in climate. There is no set climate equation, but each of these factor in. Take each into consideration and your end result will be a realistic climate for that area. Let me know if I missed anything! ]
[Question] [ This question is inspired by the answer for [another question](https://worldbuilding.stackexchange.com/a/184081/79119). What changes in technological development after the World War 2 could have led the telex machines to be more popular than telephones, worldwide (especially in underdeveloped countries), by 1980? Transmitting a small message from a punched tape, using Radioteletype, would have been much cheaper, and much more affordable for poorer people in underdeveloped countries, than using telephones. Some technological development could have enabled it. What are the most scientifically plausible scenarios where this could have happened? [Answer] ### Western Union sets up Japanese or Chinese offices after WW2. With a US occupation force in Japan after the WW2, this could've even been ordered by the US president. The ITA2 system (from 1924 onwards) had 5 bits per character, and was really only suitable for the English language and those sharing its alphabet, it had 2 channels of 32 characters, one for A-Z, and one for numbers/symbols, giving an effective alphabet of about 60 characters. Other languages had to encode their characters in English, eg "Æ" -> "AE", or have their own local standard (Germany in the 1930s had their own standard incorporating Ä, Ö, Ü and ß/ss). Japan and China couldn't use it efficiently, as their written language has many characters. Thousands. This is where the fax machine came from — Japan couldn't use the telex system with their complex alphabet. Had Western Union set up offices in Japan or China, their language would've necessitated an extension to the telex standard. You'd basically get a team at Western Union doing a Unicode-like project and rolling out UTF-8-ish (or something in the same vein, probably a dynamic code page shift or something for maximum efficiency) in the 1950s. Going to the effort to include all Japanese and Chinese characters you might as well include (or at least allow room for growth for) all the other Asian scripts, Russian characters, etc. Then all the effort that went into the fax machine would've gone into the telex network. We came so close, they had even invented a keyboard for this: [![enter image description here](https://i.stack.imgur.com/nZYbn.jpg)](https://i.stack.imgur.com/nZYbn.jpg) Close-up: [![enter image description here](https://i.stack.imgur.com/BPSDK.png)](https://i.stack.imgur.com/BPSDK.png) ([Source](https://en.wikipedia.org/wiki/Japanese_input_method)) [Answer] **Digital telegraphy gets an earlier start.** 1. 1943 - The [Colossus Computer](https://en.wikipedia.org/wiki/Colossus_computer) is invented. This is the first digital computer and is used to break codes. timeline diverges.. 2. It is realized that multiple Colossi working in parallel can greatly reduce the time for computation, and the redundancy also reduces the impact of mechanical failures. The parallel Colossi must communicate with each other and their language is binary. Binary radio communication is established to link the computers. 3. Binary computers can do more than solve math problems. With light speed radio communication and redundant brains, computers model complex events and even direct real time operations in the real world. The year is 1955. 4. Much of the binary bandwidth established for these computers is not used at all times, and is available for other functions. Sending binary text messages is an obvious use. Civilian and other human to human communication is sent using the same binary radio channels, and results in a telex like message when the binary is translated to characters. They can be any characters and in fact are. Nonlatin characters find their way into the Latin alphabet, initially serving specialized purposes but then being incorporated into words. The same is true for languages using non-Latin alphabets. Except for Greek which somehow still stays pure; they have practice at that. 5. For all intents and purposes, the Internet comes into being by 1969. Computers rule the world in a way that would not be seen in our timeline for another 30 years. Text messages descend directly from telex and become the standard mode of communication. Spoken word telephones are a charming anachronism. [Answer] Essentially you'd have to invent most of the modern cell phone: an input system and display that doesn't depend on mechanical devices printing things on paper. This was basically the email system of the 1990s. Had cell phones not been developed, a more widespread email system linked to "phones" could have easily replaced a lot of calling. Indeed, it did displace a lot of voice calling in university & commercial environments where everyone had ready access to a computer. [Answer] It would have taken cheap telex terminals that could be placed on every desk. In real life, I have had the choice between sending a telex or making a phone call. I had a phone on my desk, but would have to take a telex message to a central communications office. Unless there was some complication such as international calling and time zone differences, it was much quicker and easier to use the phone. [Answer] ### Encryption declassified Telex was how the [Lorenz](https://en.m.wikipedia.org/wiki/Lorenz_cipher) machines communicated. After WWII, the Lorenz and Enigma encoders were kept classified, as was the work of Bletchley Park. Some documents are still not available, but it is widely suspected that these were given to friendly nations who had no crypto themselves, as a "good enough" solution to get them up and running. (And of course a solution the British and Americans could break.) Suppose this didn't happen, and the existence of Lorenz became widely known. Companies used telexes extensively for vital information, and there was always the problem of sending in the clear. Widespread military-grade crypto would have been adopted immediately. From there, all it needs is someone to see that it doesn't want to be printed on paper tape, it can go on a display. That could be multi-segment Nixie tubes, one of the new CRTs, or something. Once you remove the paper tape, it becomes a mechanism people can use to chat directly. Remember that we have perfectly good phones today - and we still often use text chat. It may not replace phones, but it will certainly get widespread adoption and heavy use, just as text chat has since it first came around. [Answer] An obsessive need for a permanent record. You need a trained person to translate it, and so either to learn it yourself (at the expense of at least time and probably money) or to pay someone else to do it. It's slower than the telephone. Its only possible advantage is that you can preserve the tape. [Answer] The main driver for a popular telex system would have been the price of copper. Copper was required for telephone lines but radio transmission of telexes avoided this. [Answer] Your want a tech approach so that is what I will give you. A lot of World War Two era tech was actually made out of stamped sheet metal which was used in earlly mechanical calculators. Multistampe to form shapes and die cutting to cut out the parts. Now change that to happenning 60 years earlier and throw in some dicoveries that happened to late to really affect that industry. Using advance methods light is directed onto a mask to etch very precise dies for mass production stamping of sheet metal parts.Throw in a henry ford type character around 1870's that comes up with the model T of telex and have radio communication ealier. Then mess up the development of the telephone. The original telephone developed by bell had a serious issue with the microphone. Edison was hired to make a new improved version of the microphone. Have that never happen and no one either figure it out or have the answer expensive. So cheap tough telex machines are everywhere and telephones are a neat novelty where you try and figure out what whoever is on the other side is saying. As it is it took moch longer for radios that could be developed to be able to handle voice so that could still be a issue as well. The early marconi tech was strictly morse only even though phones had been around awhile by then. [Answer] An answer for current times: how about some sort of pandemic that induces deafness. If a substantial portion (20%?) of the population, especially older adult population (those with the money) were deaf, telex would soon become more popular, particularly if discrimination laws were passed mandating that any business with a telephone also had a telex. ]
[Question] [ So the setting is that we are several hundred years in the future, and scientists are sending humans to the surface of Venus in reinforced vessels similar to submarines or whatnot. We will assume that the tech to pull this off exists in this universe, as that's not what I'm asking about. I'm mostly concerned about whether such a vessel would float in the air naturally. I would assume it would float in a manner similar to a submarine, given that the air pressure outside would be 90x that the pressure inside, but I don't know how much the fact that it is air instead of water changes this. The fact that airships and hot air balloons float makes me think they would, but I'm not sure if the amount of buoyancy required for such a vessel to float in the high-pressure air would be different than what's required to float underwater. I'm also somewhat curious what the best way to propel a vessel through this atmosphere would be (propellers, jets, etc), although this question is secondary. (smaller vessels would probably use electricity while larger vessels could potentially have small fusion reactors aboard them). [Answer] ### Yes. Many unexpected things will float in the atmosphere of Venus. [![enter image description here](https://i.stack.imgur.com/VwpYb.png)](https://i.stack.imgur.com/VwpYb.png) This 40 ft shipping container weighs 4.2 tonnes, and has a volume of 67.7 cubic meters. Giving it a density of 62 kg/m^3. The density at the surface is about 65-67 kg/m^3. This means that the shipping container will float upwards off the surface and up into the troposphere, potentially getting up to 65 km off the surface. That shipping container will behave like a helium balloon. This should give you an indication of how easy it is to get something to float on Venus. Your vehicle needs to be lighter than a standard Earth submarine (67 kg/m^3 is a lot less dense than seawater), but the concept of a buoyant craft on Venus is sound. (Pressure and temperature will be design issues, however). Humans won't float, we'll fall to the surface. [Answer] It depends on how the vehicles are designed. In particular, the ratio of the 1-atmosphere volume occupied by humans needs to be small enough so that the overall density is greater than the density of the Venusian atmosphere. You could even design the vehicle with varying density, like a submarine. You would let atmosphere into the ballast tanks to descend, pump it out to ascend again. See e.g. Larry Niven's "Becalmed in Hell" <https://www.baen.com/Chapters/9781481483605/9781481483605___6.htm> [Answer] Short answer: It depends The density of air at the surface of venus is quite high with around 67kg/m^3 But so is the pressure (yes, these numbers are related). So as long as the overall density of the vehicle is less than 67km/m^3 AND it is not crushed AND can hold a low pressure inside (either by being gas teight or by pumping gas out faster than it ingresses) AND it can do so in up to 400°C and rain of sulfuric acid (among other nasty things) it will probably float. It's mostly an engineering challenge to build something that can withstand the pressure AND is still light enough... Maybe a helium filled balloon is still the easier solution. Good luck! [Answer] Not only near the surface, but even in the Earth-like parts of the atmosphere. Wikipedia has a good run down on ideas for habitats in the atmosphere of Venus: <https://en.wikipedia.org/wiki/Colonization_of_Venus#Aerostat_habitats_and_floating_cities> The key part is that "breathable air (21:79 oxygen/nitrogen mixture) is a lifting gas in the dense carbon dioxide atmosphere" (quote from the current version of the Wikipedia section linked above). A human-livable habitat should definitely float in the upper atmosphere, as long as you don't weigh it down too heavily. Given that, you should definitely be able to have submarine-type vehicles floating in the lower atmosphere. ]
[Question] [ In a world where people worship different gods and have different principles, how does a government assimilate those gods (make them coexist without one god being superior)? Clarification: I'm asking about how the government would guide and enforce it and maybe the prerequisite. Oh, and the gods don't actually exist. Edit: The world is ancient, with near-medieval technology, and science isn't really developed. In real world terms, its like I'm asking how ancient Greece or Rome made multiple gods be under the same pantheon and keep adding new ones without backlash from the people even though the new gods have different principles. [Answer] In real history, we have two examples of how something similar was done, so that we cannot say how to do it *in general*, only how it worked in the Antiquity. ## In the Antiquity, in general In the Antiquity, in Europe and in North Africa, and in the Near and Middle East, just about everybody was a polytheist, with the one well-known exception, and it was generally and commonly accepted that different peoples had different gods. A Greek would not have expected an Egyptian to worship the Greek gods; an Egyptian would not have expected a Babylonian to worship Egyptian gods; a Babylonian would not have expected a Hittite to worship Babylonian gods. Moreover, it was understood that religion was something a person imbibed with their mother's milk, and was not expected to change; so that foreigners who settled in another city were understood and expected to continue worshipping their original gods. All this worked well as long as peoples didn't mix too much, that is, as long as foreigners remained foreigners, and as long as nobody went about claiming that their God or gods were the only (or even the topmost) God or gods. Who cares that the foreigners worship? They are foreigners. ## In the Antiquity, specifically: *interpretatio Romana* But then came the power of Rome, and, for its own imperial purposes, Rome introduced the idea that citizenship and allegiance are distinct from ethnicity; for the first time in history, they accepted that one did not have to be *born* a Roman, one could *become* a Roman; and, even if one didn't want to become a Roman, they owed *allegiance* to Rome. A side-effect of this admirable openness was that it became somewhat important to put a little order in this business of multiple concurrent sets of gods. Note that Rome did not reach such a progressive state right from the beginning. Initially, the Romans were as wary of foreign gods as anybody else; one of the oldest monuments of the Latin language is the famous [*Senatus consultum de Bacchanalibus*](https://en.wikipedia.org/wiki/Senatus_consultum_de_Bacchanalibus), the Decree Against [Bacchanals](https://en.wikipedia.org/wiki/Bacchanalia) of 186 BCE, showing the early Roman state in full repressive mood against the spread of a foreign, in this case Greek, cult. But, as the territory under Roman Power (that's what *Imperium Romanum* actually means) expanded, this repressive position became obviously counterproductive, so the Romans appropriated a Greek idea and elevated it to the rank of political principle. The Romans did that quite often; [*Graecia capta ferum victorem cepit*](https://en.wikipedia.org/wiki/Greece_in_the_Roman_era), as [one of their poets said](https://en.wikipedia.org/wiki/Horace): captive Greece captivated her rude vanquisher. The idea in question was the [*interpretatio Graeca*](https://en.wikipedia.org/wiki/Interpretatio_graeca), a device used by Greek historians to explain foreign religions to a Greek audience. In its original Greek instance, this consisted in drawing parallels between a Greek deity and a foreign one, so that, for example, Herodotus could explain to his readers that the Egyptian gods Amon, Osiris or Ptah were sort-of like Egyptian variants of Zeus, Dionysus and Hephaestus. They weren't the same, there were differences, but they could by understood by comparison. The Romans made on more step, and in their officious (yet never "official") *interpretatio Romana*, they made foreign gods notionally the same as Roman gods. Odin was sort-of like Mercury, because he was smart and cunning and had a winged horse; sort-of like? No, he *was* Mercury, it's just that those barbarian Germans used a different name. Thor was sort-of like Jupiter, because he wielded thunderbolts; why not make him to *actually be* Jupiter? And similarly, [Tíw](https://en.wikipedia.org/wiki/T%C3%BDr) (Týr, Ziu) was only a name of Mars, and [Freya](https://en.wikipedia.org/wiki/Freyja) a name of Venus; which we can still see in the names of the week, which in Germanic languages go Tues-day, Wednes-day, Thurs-day, Fri-day, with the Germanic names of the gods, paralleling the Romance Marte-dì, Mercole-dì, Giove-dì, Vener-dì, which continue the Roman names of the gods. *Quot hominum linguae, tot nomina deorum*, wrote [Cicero](https://en.wikipedia.org/wiki/Cicero) in his book about the [*Nature of the gods*](https://en.wikipedia.org/wiki/De_Natura_Deorum): the gods have as many names as humans have languages. How did they reach this state? It all began with the Romans' exposure to the Greek mythology. The Roman and the Greek religions were very different, with remarkably few points of similarity, other than the general look (they were both luxuriantly polytheistic) and a very small number of shared deities of Indo-European inheritance. Jupiter and Zeus are really the same, as are [Vesta](https://en.wikipedia.org/wiki/Vesta_(mythology)) and [Hestia](https://en.wikipedia.org/wiki/Hestia), or [Aurora](https://en.wikipedia.org/wiki/Aurora_(mythology)) and [Eos](https://en.wikipedia.org/wiki/Eos). But [Minerva](https://en.wikipedia.org/wiki/Minerva) is profoundly different from [Athena](https://en.wikipedia.org/wiki/Athena), [Venus](https://en.wikipedia.org/wiki/Venus_(mythology)) is definitely not [Aphrodite](https://en.wikipedia.org/wiki/Aphrodite), and Mars shares with Ares only their combative attitude. Nevertheless, the Greek religion had something the Roman religion didn't, namely, mythology. The Roman native deities are more in the nature of abstract ideas, they don't look like humans, they don't behave like humans and they most definitely don't have thrilling adventures in the human world. Boring. So, for literary and artistic purposes, the Romans imported the Greek mythology wholesale, and used it as if it was their own, making the obvious divine identifications. In the state religion, in the stately rituals, the original conception prevailed and remained active, but in poems and novels, in the statuary, and in decorative pictures, the Roman names were applied to the much more adventurous and relatable Greek gods. To exemplify, around the middle of the 3rd century BCE, [Livius Andronicus](https://en.wikipedia.org/wiki/Livius_Andronicus) renders the first line of the Odyssey (*ἄνδρα μοι ἔννεπε, Μοῦσα, πολύτροπον*, andra moi ennepe, Mousa, polytropon, "tell me, Muse, of the well-versed man") as *virum mihi Camena insece versutum*, seeking to establish an equivalence between the Roman [Camenae](https://en.wikipedia.org/wiki/Camenae) and the Greek [Muses](https://en.wikipedia.org/wiki/Muses); but one hundred years later, [Ennius](https://en.wikipedia.org/wiki/Ennius) writes shamelessly in his [*Annals*](https://en.wikipedia.org/wiki/Annales_(Ennius)): *Musae quae pedibus magnum pulsatis Olympum*, "Muses, who with your feet beat mighty Olympus"; thus giving up any pretense that a Roman audience did not know who the Muses were or what the Olympus mountain was. Once the Greek gods were accepted as equivalents of the Roman gods, although everybody knew they weren't, it was not hard to extend this to the other peoples of the Empire. Where the Greek went, the Gauls, and the Germans, etc. followed. In later times, the Romans started accepting that there were deities which didn't even have Roman names; and in Rome the cult of Cybele and Isis prospered. Once a dividing wall is breached, there is no division any more. It should be noted that this identification of foreign gods with Roman gods was purely notional; it had exactly zero effect on the ground in those lands were those foreign gods were actually worshipped. The Romans did not go to Cyprus to explain to the natives that their Aphrodite had been officially identified with Venus and the cult of Aphrodite in Cyprus had to conform to the cult of Venus in Rome. They did not go to Germany and explain that Woden / Odin had been identified with Mercury and the Germans should immediately make him a god of thieves and merchants. No; the *interpretatio Romana* was for the use of Romans, so that they would feel at home in a diverse world. As long as the peoples of the Empire agreed to build a temple for the Emperor and to perform the required rituals, all was fine. Nobody went into silly theological disputations about which god came first, or which god is paramount; such discussions were considered light entertainment, suitable for a pleasant afternoon with friends and a crater of mulled wine. [Answer] The first step would be the peaceful coexistence of many religions. * Force all assimilated tribes to accept the supremacy of the government in all *temporal* matters. Any resistance means heads will roll. * Force all assimilated tribes to allow missionaries into their territory, and to allow their people to convert to another religion without *temporal* discrimination. Again, resistance means that heads will roll. The second step would be the acceptance of a pantheistic worldview in general, if the assimilated tribe was monotheistic. This might involve workarounds like the trinity, with different aspects of one god, or promoting the worship of lesser angels and saints in addition to the main deity. The third step is to let people *mix and match* from the pantheon. Seafarers worship the sea god and are reasonably polite but not worshipful to the war god, warriors do it the other way around. If those three steps work out, you have generally pantheistic tribes which accept the principle that people worship different gods in different ways. Two options for the final integration: * Interpret new additions to the pantheon as [different interpretations](https://en.wikipedia.org/wiki/Interpretatio_graeca) of an existing god. *"Oh, that's just what those barbarians call the thunder god, they don't know better."* The problem is that the high priest of the thunder god might insist on speaking for all thunder god priests. Ares is Mars, Zeus is Jupiter. * Actually expand the pantheon. There is not just one war god, there are many. Ares and Mars cover war, but Athena is a warrior as well ... [Answer] **Utilitarism**: I worship as many gods I need, as long as I believe that they fulfill my needs. I need money? I worship Grand. I need fortune in love? I worship Base IV. Incidentally, this is why the Roman religion was so open to foreign divinity: as long as the religious acts were thought to contribute to the prosperity of the community, they were accepted without excessive nitpick. As a government, just avoid enforcing rigid walls that delimit what is good religion and what is bad religion. [Answer] While peaceful coexistence of religions is lovely, it's not always how this works. Another way to achieve your goal is with a combination of co-opting an existing "lessor" religion mixed with subversion of the dominant religion. Christianity is an expert at this, specifically Catholicism and other pre-split sects. Look at their largest holidays: Christmas and Easter. Most modern-day practices surrounding these holidays come from pagan holidays that were folded into the Christian ones as Christianity took over (often but not always Celtic paganism). When Christians invaded the Americas and their religion became dominant, worship of local Gods continued, but subverted into worship of saints and especially the Virgin Mary (multiple versions of Mary that only exist on this continent). In Mexico and other Latin American countries, much of the details of "the Virgin" and various saints were wholesale borrowed from existing deities but folded into the cast of characters the Christians approved of. Entire books have been written about this phenomenon. As well as countless articles. A few sources: * [The Black Madonna in Latin America and Europe](https://unmpress.com/books/black-madonna-latin-america-and-europe/9780826341037): Tradition and Transformation, By Malgorzata Oleszkiewicz-Peralba * [Female Divinity in South America](https://www.suppressedhistories.net/goddess/fdivsa.html) * [Nuestra Señora de la Santa Muerte](https://en.wikipedia.org/wiki/Santa_Muerte) (not quite folded into Catholicism but certainly influenced by it). While Christianity is monotheistic and saints, prophets, etc are not considered deities, one might argue that the system of Catholic saints is in fact a pantheon. While the saints are based on real people, in many cases their lore comes from gods of other traditions. In some Catholic cultures, they are prayed to and treated as if they were gods, they just don't get that label because the Church would not approve. In your world, you don't have to make the dominant religion monotheistic. There may not be a dominant religion, or there could have been in the past and now there isn't. There are lots of possibilities on an invented world. [Answer] Compartmentalize the gods into departments. As long as the department's don't overlap in terms of who gives what blessing, the issue of seniority won't come into question, only the usefulness, and in turn the number of followers. For e.g. if you have three gods of war, making them the gods of land battle, naval battle and aerial dogfight. They are all equal in position, but not equally useful or popular, as land battles have bigger armies. So God land war will have more followers, and his temple will be more widespread. On the other hand, god of jetplanes will have few but elite followers, bringing more influence and money to the temple. [Answer] Add "God Parents". Announce a new God or Goddess (or both!) at the very top, who "previously" were only known about by the Ruling Class and highest of High Priests, but is now allowing the secret of their existence to be known. But, they're still only for the Elite in the Government to Worship. Then declare that the other Gods and Goddesses are all descendants or in-laws of the new Top-God. That, while the Gods may sometimes fight and argue, they are all one big family, and they want their followers to do the same. Not to suddenly be all happy and buddy-buddy with each other (after all, most of you know what siblings can be like!), but rather to be open to reconciliation, and never to take it "too far". ]
[Question] [ This is my first question on this site, which I recently found and can’t get enough of. In many time travel scenarios, the machine is static in space. My question is how to explain this. For example, in HG Wells' works, it's always in the same location. I’m referring the earth rotating around the sun, as well as the sun moving across the cosmos. Even if you made a timeship, moving a couple hundred years could mean light years, without FTL you are stuck in deep space. I have also contemplated using a time machine as a sort of FTL calculating some time in the past or present when another star system will be in the same location we currently are. Is there a realistic answer to why we stay grounded in the same space while moving through time? It might be easily answered by the theory of relativity, and I just don’t understand. Note: I’m not thinking about using near light speed time travel, because obviously you would be moving anyway. Thinking more of the getting inside and flipping some switches. [Answer] The concept of space and time being combined into [spacetime](https://en.wikipedia.org/wiki/Spacetime) may be the relevant factor here. It is possible that while you are traveling through time, that you will still be under the influence of Earth's gravity. Earth's gravity well might function as sort of an anchor or tether, that will stop you from flying off into the cosmos. Often times in fiction you have to feed a time machine a "time" and "place". It is possible that these fictional devices have a sort of GPS built in that will calculate where a certain spot on Earth will be located in the cosmos at any given time. So long as you don't travel back to before the formation on the Earth you should be just fine. [Answer] ## Use gravitational mass as reference. *(I wrote a time-travel story years ago and I stumbled accross this problem too. In my novel, I explained it in the simplest possible way and discarded any question that may have resulted from it, because plot.)* **The device takes the mass of the most dense object nearby as a dot of reference in time, this object being Earth itself.** When time-travelling, taking a *place* as a point of reference makes no sense, since everything moves, either within the cosmos, or on Earth itself: continents may rise and sink while you are time-travelling, and the only reason you do not end miserably into molten rock is plot armor. But if your time-machine has a gravity densimeter (I just made up that name, feel free to make up a new one by yourself), it can estimate the distance from the most important gravitational mass nearby, and adjust itself to always stay tangent to this mass, while keeping its orientation (the differences in the mass of the Earth being negligible on a grand scale). Thus, not only you can time-travel on Earth without moving (or so little that it will not affect anything), but also if you have to time-travel on a bigger scale, you can take any other astral object as reference, given it has a massive gravitational mass: be it a planet, a star, a black hole, etc. Of course, **the higher the density, the higher the time-distorsion factor will be**. [Answer] The easy way to resolve this is to just have the machine "exist" throughout any time it travels through. Any forces applied to it from the outside can move it like normal. That's why it stays where it is (and also why it doesn't fall through the planet). [Answer] Speed can only be determined relative to something else. Why wouldnt time be different? When traveling the time machine has to have a referencepoint or it might lack the ability to travel at all. You might be able to travel as well but with the time machine already traveling through time it might just be too difficult to travel. And being off with your aim could also mean that you now occupy a rock, or any distance above ground from 1mm to 100.000km. Its not worth the risk. Additionally we know that gravitational effects also affect time. It might simply be that the time machine function only when close enough to a large enough mass and use the gravitational effects to travel. When traveling through time you have to keep the time machine close enough to said mass or you get ejected. Traveling to another location through the gravitational effect of the planet changes the effects the time machine uses, making it uncertain where you end up... And when. Better stick to the same location! [Answer] It's easy to make a time machine -- just get yourself a big cardboard box, climb in, and you will move forward in time at the rate of one second per (subjective) second. When you get out, it's still in the same place, relative to the building it's in. And if that's true, then it should be true for any other time machine that isn't also a car or a plane or something like that. Only if it somehow "teleports" through time would there be a problem keeping it in the same place -- or steering it to some other place of your choice, TARDIS or Mr. Peabody style. [Answer] Time Travel from Stationary Position? We might attempt look at relative motion versus absolute motion. If a traveller were to come to an *absolute stop*, to become absolutely stationary, he might find that his universe (capital U?) has instantaneously flown away from him, and that in becoming absolutely stationary he has somehow effectively detached himself from said universe (and therefore created another one, depending on the initial definition of 'universe'). But (according to whom?) he may be said to have motion relative to the universe he has just detached from, and in instantly coming to an absolute stop, he has done exactly the opposite. Zero motion may be absolute motion - to the traveller at least, he has for all intents and purposes superpositioned himself upon the universe, where previously all straight lines are now curves. With some further quackery it is around this point there might be room for time travel without appearing to move. ]
[Question] [ In my fantasy universe, there is a disc-shaped world that has a flat surface that has roughly the same atmosphere as Earth (see [this](https://metrouk2.files.wordpress.com/2017/02/flat-earth-1.jpg?quality=80&strip=all)); the atmosphere moves along with the world. There is no gravity in my universe - rather, objects on the world are held down by a constant upward acceleration of the world ~9.8 m/s2 through infinite (empty) space with no other cosmic bodies. My question is, would the force produced by this acceleration be effectively indistinguishable from the force produced by gravity on Earth? Would this affect the behavior of airplanes in any obvious way? [Answer] # TL;DR Your world will experience constant, uniform gravity. Everything is accelerating upward at the same rate - but this isn't the case in our universe, as gravity follows (approximately) an inverse-square law, and more specifically the framework of general relativity. On Earth, this isn't the case, and there are a number of different effects. Some are obvious and some aren't: * Gravity varies across Earth's surface. * Gravity varies at different elevations. * Gravity varies over short changes in height - measurable with sophisticated equipment. * Tidal forces arise from differences in gravity between multiple points. ## Changes in surface gravity Gravity isn't *quite* uniform on Earth's surface. Earth rotates, and so the equatorial radius is larger than the polar radius by about 22 km, meaning that gravity is stronger at the pole than at the equator. [This could have some effects](https://xkcd.com/852/), but nothing immediately visible to the human eye; it's only 0.6%. Local changes in elevation from surface topology [also affect gravity](https://en.wikipedia.org/wiki/Physical_geodesy), keep in mind that even Mount Everest is only about 9 km above sea level. [Mascons](https://en.wikipedia.org/wiki/Mass_concentration_(astronomy)) - local gravitational anomalies - are present on the Moon, but aren't important on Earth, although such deviations can be mapped: [![enter image description here](https://i.stack.imgur.com/L3d5O.gif)](https://i.stack.imgur.com/L3d5O.gif) Map of gravity variations on the seafloor. Image credit: NOAA. In short, if you travel, a long distance on Earth, you might be able to see a difference in surface gravity, but only with fairly good measuring equipment. If you travel anywhere on this world, you shouldn't see any variations. ## Changes in the atmosphere Gravity also gets weaker if you rise through the atmosphere of Earth, thanks to the inverse-square law. Again, even high-altitude aircraft like the [U-2](https://en.wikipedia.org/wiki/Lockheed_U-2) would only be able to measure deviations on the order of about 1%, and an aircraft is more affected by atmospheric turbulence than this change in gravity. Therefore, that change would be hard to measure. The same goes for tunnels under Earth's surface, but even [the deepest man-made hole on Earth](https://en.wikipedia.org/wiki/Sakhalin-I) is only 12-13 km deep. ## Small-scale changes There have been experiments that have shown that general relativistic effects indeed change as predicted at different heights above Earth's surface - the [Pound-Rebka experiment](https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experiment) was a famous one, as was the [Hafele-Keating experiment](https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment). The former tested changes in gravitational redshift; the latter tested changes time dilation from special and general relativity. These changes wouldn't be present in your flat, accelerating world. Again, though, this requires sensitive measuring equipment. ## Tides and tidal forces Credit goes to Nat for reminding me of this one. Tides on Earth arise from the positions of the Moon and Sun in relation to one another. With no gravity, you'd see no tides - even if a moon and star appear in the sky. Not also that ["tidal forces"](https://en.wikipedia.org/wiki/Tidal_force), in a different sense of the word, arise from a gravitational gradient - a difference in the force of gravity between two points. In a case of uniform acceleration, you won't see that sort of thing. [Answer] > > My question is, would the force produced by this acceleration be effectively indistinguishable from the force produced by gravity on Earth? > > > Yes. That's the central point of Einstein's Sealed Elevator Thought Experiment that demonstrates the Equivalence Principle. <https://en.wikipedia.org/wiki/Einstein%27s_thought_experiments#Falling_painters_and_accelerating_elevators> <https://upload.wikimedia.org/wikipedia/commons/c/c2/Equivalence_principle_thought_experiment.png> [![enter image description here](https://i.stack.imgur.com/luJJM.png)](https://i.stack.imgur.com/luJJM.png) > > Einstein later refined his thought experiment to consider a man inside a large enclosed chest or elevator falling freely in space. While in free fall, the man would consider himself weightless, and any loose objects that he emptied from his pockets would float alongside him. Then Einstein imagined a rope attached to the roof of the chamber. A powerful "being" of some sort begins pulling on the rope with constant force. The chamber begins to move "upwards" with a uniformly accelerated motion. Within the chamber, all of the man's perceptions are consistent with his being in a uniform gravitational field. Einstein asked, "Ought we to smile at the man and say that he errs in his conclusion?" Einstein answered no. Rather, the thought experiment provided "good grounds for extending the principle of relativity to include bodies of reference which are accelerated with respect to each other, and as a result we have gained a powerful argument for a generalised postulate of relativity." > > > . . > > Would this effect the behavior of planes in any obvious way? > > > If the disc world is perfectly flat, and there are no edges, then the atmosphere will quickly slide off the edge of the disk. If the world has a (60-65 mile) wall around it, then the air will stay in. [Answer] What accelerates the world discs? Is it some universal force which propels rock or dirt upwards? Of course, it could also be some universal force which accelerates non-rock/non-dirt material downwards. So, the obvious way to build a spaceship would be to cut some "world material" out of the disc planet. It would not only be weightless, but since the acceleration is a constant $~9.8 m/s^2$, other stuff could be piled onto it. It would we some sort of anti-gravity transportation medium. The "constant acceleration" premise sound implausible? No, not at all - it is actually a **requirement**! The acceleration **needs** to be independent of the amount of "non-world material" piled onto it. Otherwise, **the world disc would tip** as soon as the non-accelerated mass was unevenly distributed across the world. One the disc tip, water and air would flow downwards, causing the disc to continue to tip even faster. Water and air are other stuff would fall off the disc, with predictable results. This non-accelerating stuff would also eventually hit lower/trailing disc planets at relativistic speeds. Your "airplanes" would be floating rocks, like air ships (zeppelins), but without the hassle. They would also be spaceships, but once you leave the atmosphere (that would be easy), regular control surfaces do not work any more. Once you leave the wold disc area (floating sideways), you need reaction drives. Now, that sucks hard...well, not for the guys piloting the rock. They can just launch material into the opposite direction to generate thrust into the desired direction. Not an issue as long as they use "floating rock" material...but very much an issue for lower/trailing worlds as soon as they get the (obvious) idea of launching garbage. Chances are good that, eventually, some other world will get hit by a turd impacting at hyper-relativistic speed. --- Note: even photons (heat/light radiated from the world or its sun) would have turned into extremely hard radiation in the lower regions of the universe. So only the "top" worlds in the infinite universe would be inhabitable at all. [Answer] Since there are no other cosmic bodys in your universe, you also have no Sun. No Sun means no sunlight and no sunlight means your world will have a temperature as close to absolute zero as Heisenberg permits. (Apart from geological activity [which shouldn't exist without gravity, in my opinion] and radioactivity, if it should exist.) Thus, your planes couldn't take off, since there wouldn't be a gaseous atmosphere available. ]
[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. I'm working on a lost colony type story where 500 colonists have and their ship went missing in interstellar space. I thought of designing a realistic starship design and kind of remembered a quirk that I was curious about for some time. Most sci-fi or actual starship designs utilize the push method of forward propulsion, with engines placed on the back of the spacecraft. [![spaceship design](https://i.stack.imgur.com/qkgYW.jpg)](https://i.stack.imgur.com/qkgYW.jpg) [![Generation Ship](https://i.stack.imgur.com/mJHpA.jpg)](https://i.stack.imgur.com/mJHpA.jpg) But what about starships that instead utilize a tractor configuration? A prime example of this being the ISV Venture Star from Avatar. [![ISV Venture Star](https://i.stack.imgur.com/2w39i.jpg)](https://i.stack.imgur.com/2w39i.jpg) I read that the tractor configuration is efficient because aside from actively pushing the ship, it drags it from its back. For such a long trip, mass saving is necessary. Every gram counts. If you pull a ship using a tensile truss like Venture Star does, it requires less mass. What pros/cons does a tractor configuration have from the traditional propulsion method? From a realistic perspective, how will the size of the ship affect such and the power needed to propel such a craft? Like, can something as big as a Generation Ship utilize a tractor-configuration and ships of such proportions? [Answer] **TL;DR: tractor spacecraft with tensile structure are great for everything that doesn't require many frequent changes of direction or acceleration.** Shuttles and warships probably wouldn't use that design, but for everything else there's a reasonable chance that the benefits outweigh the downsides. --- In my ever-so-humble opinion, the primary benefit of tractor-configuration spacecraft is reduction in radiation exposure. To my knowledge, almost all tractor-configuration rocket designs of the last 60-70 years use a tensile structure... there's no rigid spine. (Note that some people still think that a rigid rocket in tractor configuration is somehow more stable, which isn't the case. [Goddard's first liquid-fuelled rocket](https://en.wikipedia.org/wiki/Robert_H._Goddard#First_liquid-fueled_flight) used that design, and he went on to demonstrate it was no better than a pusher-rocket in terms of directional stability). There are a few immediately obvious real-world benefits to using a tensile structure. ## Radiation Protection You can protect yourself from radiation by putting enough mass between you and the source, or you can move the source far enough away from you that the inverse-square law protects you from the worst of it. Some early work on this notion can be found in the form of the [Convair Helios](http://www.projectrho.com/public_html/rocket/realdesigns.php#heliosski2) which used a nuclear thermal second stage. The San Diego Air and Space Museum has [a nice collection of images online](https://www.flickr.com/photos/sdasmarchives/), including these wonderful illustrations by John Sentovic for the original proposal in 1959 (which I'd like to find a copy of, but can't). [![Convair Helios second stage in orbit, showing log tethers separating nuclear rocket from crew section](https://i.stack.imgur.com/a5XX7.jpg)](https://www.flickr.com/photos/sdasmarchives/16064865896/) The distancing was far too short of course... I won't go into details here, but a 300m separation from a gigawatt nuclear thruster would have been a bit spicy for the payload, which would have included humans (at least at takeoff). Here's another illustration from the same series: [![Two Convair Helios rockets, one landed on the moon and the other landing, showing how the rocket would land offset from the crew section to maintain distancing](https://i.stack.imgur.com/E4d0V.jpg)](https://www.flickr.com/photos/sdasmarchives/28388911935/) This shows how the nuclear engine could lower the crew module to the ground, then move laterally to land itself, maintaining separation at all times. This is perhaps a predecessor to the Mars Science Laboratory's "skycrane" [Entry-Descent-Landing](https://www.nasa.gov/mission_pages/msl/multimedia/gallery/pia13282.html) system. Charles Pellegrino, author of [Flying to Valhalla](https://archive.org/details/flyingtovalhalla00pell) and consultant for the *ISV Venture Star design* of *Avatar* fame, thought carefully about the design of a fast interplanetary or interstellar rocket design, which he named *Valkyrie*: > > Put the engine up front and carry the crew compartment ten kilometers behind the engine, on the end of a tether. Let the engine pull the ship along, much like a motorboat pulling a water skier, and let the distance between the gamma ray source and the crew compartment, as the rays stream out in every direction, provide part of the gamma ray protection - with almost no weight penalty at all. We can easily direct the pion/muon thrust around the tether and its supporting structures, and we can strap a tiny block of (let's say) tungsten to the tether, about one hundred meters behind the engine. Gamma rays are attenuated by a factor of ten for every two centimeters of tungsten they pass through. Therefore, a block of tungsten twenty centimeters deep will reduce the gamma dose to anything behind it by a factor of ten to the tenth power (1010). An important shielding advantage provided by a ten-kilometer-long tether is that, by locating the tungsten shield one hundred times closer to the engine than the crew, the diameter of the shield need be only one-hundredth the diameter of the gamma ray shadow you want to cast over and around the crew compartment. The weight of the shielding system then becomes trivial. > > > There's considerably more information about his Valkyrie spacecraft design [on his website](https://charlespellegrino.com/nuclear-propulsion/), but do note that this isn't a scientific paper. I'm not aware of more serious studies on this style of rocket. For non-generational starships, beamed propulsion systems are more desirable than self-propelled systems, which might be part of the reason. Further discussion on this subject probably belongs in a separate question though. ## Spun Gravity It is pretty well known that you can use centrifugal forces to provide artificial gravity for spacecraft. To provide sufficient centrifugal force, you can do two things: spin your centrifuge fast, or extend the radius of your centrifuge. There are physiological limits to the "just speed it up", because the difference in centrifugal forces across a short-radius centrifuge can be quite disorienting and coriolis effects make working in such an environment challenging... there's plenty of research on this, such as [Artificial gravity space station physiological effects and design criteria](https://ntrs.nasa.gov/citations/19710014978) from 1971. The [Gemini Xi Artificial Gravity Experiment](https://www.nasa.gov/image-feature/sept-14-1966-gemini-xi-artificial-gravity-experiment) was almost certainly the first actual use of centrifugal artificial gravity in space, generating a fierce 0.15 milligees of acceleration, but if you really wanted to use this design for artificial gravity there's no reason to limit yourself. Martin Marietta wrote [Manned Mars System Study](https://ntrs.nasa.gov/citations/19930003254) for NASA in the late 80s, and one part of the study included looking at artificial gravity provision for astronauts on an Earth-Mars transit. [![Martin-Marietta artificial gravity concepts for the Manned Mars System Study. Concepts 4 and 5 show the use of long tethers connecting a habitat module with the main body of the spacecraft, with 4 having a single crew module using the spacecraft bus as the counterweight at the other end of the tether, and 5 having two spun cargo modules with the spacecraft bus at the center of the arrangement.](https://i.stack.imgur.com/cPgrH.jpg)](https://i.stack.imgur.com/cPgrH.jpg) The use of long tethers allowed for low rotation rates (~2rpm) but high artificial gravity (as much as 1 gee!). Regular pusher spacecraft could do this as well, but they'd have to carry the tether equipment in addition to their normal structure making it additional weight. Tractor spacecraft could get it "for free", so to speak. It should be obvious that you can't use this style of artificial gravity whilst your spacecraft is under thrust, but for in-system travel this should not present a problem. Everyone always goes on about constant-thrust brachistochrone trajectories, but boost-coast-brake trajectories can be almost as fast and need much less implausibly overpowered rocket motors (but that's a subject for a different question). High-speed (eg. >.2c) starships would probably not use this mechanism at all, because it would expose too much of the spacecraft to high-speed debris and particle radiation from ahead... read more gristly details in [Radiation Hazard of Relativistic Interstellar Flight](http://arxiv.org/abs/physics/0610030). Different artificial gravity designs are required for those kinds of flight, with everything tucked behind a substantial forward shielding system. Generational spacecraft with more modest speeds and shielding requirements could work just fine, though. ## Novel propulsion systems [Lightsails](https://en.wikipedia.org/wiki/Solar_sail) more or less require you to have a tractor-configuration spacecraft. Laser driven lightsails are potentially quite useful and sensible designs for both in-system and interstellar travel, and remove all that tedious mucking about with the rocket equation. Lightsail sizes need to be big (I won't go into detail about how big, but to give you decent accelerations or to push you to another star in a reasonable timescale they need to be kilometers across) and making very lightweight rigid structures that could be use for pushing is more or less impractical. High speed and high acceleration lightsails [need to be curved](https://doi.org/10.1021/acs.nanolett.1c03272) to reduce tensile stresses in the sail fabric causing tears. Making a nice curved sail with the payload tethered "behind" it is a fairly natural and simple design, in theory. [![Curved lightsail with payload tethered "behind" it](https://i.stack.imgur.com/9XZXz.png)](https://i.stack.imgur.com/9XZXz.png) Lightsails aren't the only thing you can do though. A paper for the British Interplanetary Society in the 90s gave us the [*Medusa*](http://www.projectrho.com/public_html/rocket/enginelist3.php#id--Pulse--Medusa), an Orion-like nuclear pulse propulsion system that used a curved sail-like system that the author referred to as a [spinnaker](https://en.wikipedia.org/wiki/Spinnaker) to catch the products of a nuclear explosion: [![Diagram of the Medusa propulsion cycle](https://i.stack.imgur.com/nl8Mf.png)](https://i.stack.imgur.com/nl8Mf.png) (the original paper, [Medusa – Nuclear Explosive Propulsion For Interplanetary Travel](https://bis-space.com/shop/product/medusa-nuclear-explosive-propulsion-for-interplanetary-travel/), is currently paywalled, and I have no free sources for you) The Medusa propulsion cycle is conceptually similar to Orion, detonating the nuclear propulsion unit, catching the blast in a canopy (instead of a pusher plate). The canopy is blasted away from the spacecraft, unspooling the tether as it goes. The ship then reels itself back in along the tether. This reeling-in stroke can be made much, much longer than the Orion's short stroke, providing an extended period of artificial gravity as the spacecraft is accelerated towards the sail. The shock loading is much less because the stroke is longer, reducing mechanical loads on the spacecraft and reducing the weight of the shock-absorbing system. The great length of the tether also allows the inverse-square law to provide additional protection from radiation that the much short Orion ships cannot enjoy, requiring them to carry much more shielding. ## Downsides The principle downside is that you have to care about where the exhaust jet goes. With a pusher-configuration, so long as you're in deep space then you can fart out as much toxic and intensely radioactive death gas as you like and you'll probably be OK (so long as you're suitably shielded). With a tractor configuration, you need to make sure that you are the exhaust jet doesn't impinge on any other part of the spacecraft, *and* that any radiation emitted by the jet (including thermal radiation, not just short-wavelength EM and fast particle radiation) doesn't threaten the safety of the spacecraft. The Convair Helios just had a single motor and placed the crew module sufficiently far away that the exhaust jet was expected not to be a threat, but more powerful engines can't really make that assumption. If nothing else, the tethers themselves are at risk of damage... look at the Helios image above and you can see that the tethers are mounted on booms that hold them away from the rocket's body to prevent them being melted through by the exhaust. The Venture Star design angles the two big nuclear rockets away from the spacecraft to keep the jets away from everything. [Project Rho](http://www.projectrho.com/public_html/rocket/slowerlight3.php#id--Go_Fast--Nearlight_Starships--Avatar_ISV_Venture_Star) says they're out by 3 degrees, by I can't find where he got that information from (the [Pandorapedia](https://www.pandorapedia.com/human_operations/vehicles/isv_venture_star.html) says nothing about the angles, for example, but maybe there are better sources). I'm assuming he just put a protractor up to the diagrams and artwork, and that's good enough. You can work out the thrust lost from angled jets by taking the cosine of the angle to get the vertical component. The cosine of 3°, for example, is ~0.9986, meaning that 0.14% of the thrust is wasted. That's not a trivial amount of delta-V, but it also isn't necessarily a mission-ending waste. If you don't use rockets then this really isn't much of a problem, of course. A much lesser downside might be manoeuvrability. The tractor design means your spacecraft doesn't need to have a stiff spinal structure, and that's great when you're just going in a straight line, pulling from the front, but this can present some difficulties when you need to slow down or turn and maintain tension in the structure. If you're just flying from A-to-B this probably isn't a big deal unless you have a lot of space-traffic-control manoeuvring to do, but in that case you can just use smaller pusher-configuration shuttles to fly stuff into airspace where more turning and changes of acceleration are needed. For interstellar travel, the whole "not being able to turn on the spot" thing isn't a problem at all, because turning around when you're travelling at relativistic speeds is a good way to [get irradiated to death](http://arxiv.org/abs/physics/0610030). Note that this was something that the ISV Venture Star design got *very* wrong. Flipover at .7c kills everyone. That's why Pellegrino's Valkyrie designs either used a boost engine and a brake engine (one at each end) or in the event of an emergency, reconfigured the ship to thread the crew module through the (inactive) booster engine to move it to the back of the spacecraft for braking *without* flipping the whole ship over and compromising its radiation shielding. --- Your additional questions: > > How will the size of the ship affect such and the power needed to propel such a craft? > > > If your tractor system is lighter than its pusher counterpart, then you get more cargo or more fuel and reaction mass or more shielding "for free". The size of the ship is almost irrelevant, although it will be much easier to make multi-kilometer-long tensile spacecraft, than rigid ones. > > Like, Can something as big as a Generation Ship utilize a tractor-configuration and ships of such proportions? > > > Probably not, but not because of the tractor configuration per se but because of the fact that you probably can't reasonably keep a propulsion system running across generational timescales. Your rockets will have run out of fuel, your laser emitter at your home star might not be maintained or simply might be unable to focus at such a distance. MatthieuM mentioned solar sails driven by starlight pressure alone, but even these will only provide useful thrust within the launching starsystem and all the useful acceleration will be over long before they reach their equivalent of the heliopause and the sail should be packed away safely to protect it from damage, ready for use as a solar *parachute* to decelerate at the destination system. Most of a generation ship's flight will be cruising without thrust, and so the configuration is kinda meaningless. The boost and brake phases could use a tractor-configuration, conceivably. [Answer] The engine would risk damaging the payload. While it is not exactly a peer-reviewed journal, I'd like to link [Project Rho](http://www.projectrho.com/public_html/rocket/spacegunexotic.php#id--Propulsion_Systems) on the dangers of effective drives. A tractor configuration would have two choices. * Angle the engine exhaust away from the payload, thereby reducing efficiency as multiple units cancel each other's spin. * Mounting the engines on outriggers, adding more mass to the design. [Answer] # Workable with a careful design There are several issues to consider when designing interstellar spaceships - especially generational ones. The main ones are: * **Mass**. The mass of the spaceship should be as low as possible, to save on propulsion. The start mass (including fuel) is proportional to the payload mass, as per the inverse of the *[Tsiolkovsky rocket equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation)*: m0 = mf\*e^(delta-v/ve), where m0 is the start mass, mf is the payload mass, delta-v is the velocity change you want to achieve, and ve is the exhaust velocity. For a delta-v that makes interstellartravel even remotely possible, m0/mf is likely to be very high. Hence, you want to keep the payload mass, including structural mass, as low as possible. * **Artificial gravity**. We are not designed for zero or low gravity. Besides the [well-known effects](https://pubmed.ncbi.nlm.nih.gov/11536970/) including loss of muscle mass, heart mass, bone mass and degterioation of eyesights, microgravity also [negatively affects fetuses](https://pubmed.ncbi.nlm.nih.gov/15607544/), making procreation a problem. Hence, especially for a generation spaceship, artificial gravity through rotation is required (since the ship's acceleration is unlikely to be high enough to induce sufficient pseudogravity). The rotational axis can be at any angle to the line of travel, but it would be impractical to make it perpendicular to the line of exhaust, or protection from radiation and/or particle bombardment from the exhaust will be problematic. * **Particle protection**. While interstellar space is *mostly* empty, it isn't *totally* empty. The [interstellar medium](https://www.astronomy.ohio-state.edu/ryden.1/ast162_3/notes11.html) contains roughly one atom of gas per cubic cm and dust grains (mostly less than 500 nm or ½ micrometer) with a density of 1 grain per million cubic meters. The danger from particles is close to negligible unles travelling at relativistic speeds - at one-hundreth the speed of light, every square meter cross section will be impacted by just three such particles every second, each with an energy of one-millionth of a rifle bullet, to the best of my calculations. Friction from gas is also negligible. However, given the distance and time traveled, the spaceship is bound to encounter *some* larger particles, which at these relative speeds will impact with quite high energy. It is hence best to minimize the cross-sectional areas of the spaceship in the direction of travel. As the OP mentions, the advantage of a pull engine is that it can drag the spaceship with cables rather than pushing with a rigid framework, something that potentially can reduce mass. The downside is that you have to keep all parts of the spaceship away from the exhaust, which is likely to have relativistic speeds to minimize fuel mass. Current ion thrusters have exhaust velocities around 20–50 km/s, or roughly one-hundreth the speed of light, but this can probably be improved - and given that fuel mass is exponentiallly proportional to exhaust speed (see above), even small gains in exhaust speed will hugely reduced total fuel mass. With all this in mind, I propose the following design: A spaceship shaped like a long, hollow cylinder with the payload in the 'wall' of the cylinder, dragged with cables by an engine situated forward of the spaceship along the cylinder's central axis. The narrow exhaust beam will hence pass harmlessly down through the middle of the cylinder. The reaction mass (fuel) is partly stored ahead of the engine, but mostly in ejectable compartments in the forward parts of the cylinder wall, where it shields the important parts from micro-impacts. Some of the supporting cables act as tubes to transport this fuel (possibly liquid He3 for fusion) to the engine). I will not try to make a drawing, but the cross-section of the spaceship as seen from the side will have the engine forward of the cylinder by perhaps a distance equal to its diameter, connected by cables or tubes to the inside of the cylinder wall, with perhaps a dozen cables down the length of the cylinder (and probably at least as many spokes radiating from the central engine). [Answer] **Asparagus staging to shed mass** Disclaimer: I'm basing my answer on my experience with the app Spaceflight Simulator. Imagine mounting engines and fuel tanks in a "hammerhead" configuration: At the bow of the ship is a transverse strut (or possibly more than one). At each end of each strut is some number of propulsion modules, each with an engine and fuel/oxidizer tanks. With appropriate construction techniques this strut can be made arbitrarily wide, so that the engine exhaust plume does not harm the ship. Running the engines to break orbit will consume fuel. As tanks run dry, the appropriate propulsion modules can be jettisoned much like vertically mounted stages. I can't think of any particular real-world reason to have the propulsion struts at the bow instead of the stern. That's just my approach in the app, as I often have a wide heat shield at the stern. ]
[Question] [ I plan to have dragons in my fantasy setting and wanted to figure out just how much force their wings would need to generate in order for them to fly. Rules for dragons in this setting: * Dragons, and other large flying creatures have stronger bones, muscles and skin to enable them to fly granted to them by a wide variety of conditions that varies from species to species. * The only magic dragons have naturally is their breath attacks in some dragon species. They do not use magic to fly. * While dragons are capable of flight from a young age, adult dragons are not very agile in the air and prefer to fight on the ground. Younger dragons will have agility that diminishes as they grow. * We'll be setting aside the usual problems of the square cube law for things like heat regulation and metabolism since this is a fantasy setting. I'm just looking at the amount of force their wings would need to produce in order to fly so that I can determine how much force they could exert if they tried to flap their wings to create a directed air blast to topple foes and possibly weak buildings. [![Image Source: D&D Monster manual (3rd edition)](https://i.stack.imgur.com/HoZS2.png)](https://i.stack.imgur.com/HoZS2.png) Image Source: D&D Monster manual (3rd edition) For reference, this is what I was considering for a full grown dragon in my setting at least in terms of body plan and proportions. Without any measurements of the reference image, I'm going to fall back on what one of the D&D books describe for a large dragon. 2700 pounds and a 45-50 foot wingspan will be the average. With all of that out of the way, how much force would a dragon of about that weight and wingspan need to fly? And how much of it could they direct in front of them as an attack? Would it topple humanoid foes or just kill them? Could it wreck some buildings and fortifications? [Answer] In theory if we knew the dragon's wing area, coefficient of lift, coefficient of drag, and dragon's maximum flight speed, we could determine their thrust. However we don't know your dragon's max flight speed, Cl, or Cd. --- In level flight Lift = Weight and Lift/Drag = Weight/Thrust. If we know the lift drag and weight we could then easily determine thrust. Determining lift and drag is non-trivial. Given the many unknown quantities deriving thrust this way is a bit of a dead end. ##### For completeness: The equation for lift is L = (1/2) \* d \* v^2 \* s \* Cl where: * L is lift * d is the density of the air * v is the velocity * s is the area of the wing * Cl is the coefficient of lift The equation for Drag is D = (1/2) \* d \* v^2 \* Cd \* A where: * D is drag * d is the density of the air * v is the velocity * Cd is the coefficient of drag * A is the reference area --- However if we assume that your dragon can hover we can derive some numbers that don't rely on as many undefined quantities. Unlike level flight where aerodynamic lift counteracts the force of gravity, downward thrust needs to counteract gravity on it's own. This greatly simplifies the equations. For a 2700 pound (1225 kg) dragon to hover it needs overcome the force of gravity, without the help of aerodynamic lift. At a minimum it will need to be able to produce at least 2700 pounds of force (about 12000 Newtons). Add an extra 25% to that to give your dragon some ability to climb and you're looking at a total thrust of 15000 N. Given that in level flight migratory birds like geese have thrust to weight ratios as low as 0.05 having a TWR of 1.25 should make your dragon a quite capable and aerobatic flyer. To put that thrust in perspective that's slightly less thrust than the Messerschmitt Me 262's two engines combined. While your dragons still put out a lot of thrust, unlike a jet engine where the thrust is concentrated in one location, that power is going to be dispersed over the full area of the 50ft (15m) wingspan. Getting caught in the downwash of your dragon's wings is going to be noticeable but isn't going to do any structural damage. [Answer] **65 mph winds. If you stand REALLY close.** The wingspan is about 50 feet. So each wing is about 25 feet long. For simplicity let's say each wing is a triangle 25 feet long and oh I don't know. . . . 15 feet high? Then the wing has surface area $(25 \times 15)/2$ square feet. There are two wings so the total flight surface is $25 \times 15 = 375$ square feet. If the dragon weighs 2700 pounds then 3750 is a reasonable force. That's 1050 lbs of upwards force once you overcome gravity. So the pressure on the wing surface is $3750/375 = 10$ pounds per square inch. The dragon flapping its wings generates a shockwave that pushes stuff over with pressure equal to 10 pounds per square foot. Looking at [engineering charts](https://communities.bentley.com/products/pipe_stress_analysis/w/pipe_stress_analysis__wiki/33136/22-how-to-convert-from-wind-loads-from-mph-to-psf-in-autopipe) suggests that's equivalent to windspeeds of about 65 mph. Well that's assuming you are right next to the wing as it flaps. The shockwave will disperse as it travels further from the wing. So you get at most 65mph winds. Likely much less. How strong is 65mph wind? [Well here is a loud man in a wind tunnel to demonstrate.](https://www.youtube.com/watch?v=pmJ8tXTcCfE) It seems 70 mph won't take you off your feet if you lean slightly forwards and 65 mph is weaker than that. Note the man in the video is bald. That makes him more aerodynamic and better at resisting winds Maybe 65 mph would knock you down if it took you off guard. The dragon would have to sneak up behind you and then take off suddenly without you noticing. [![enter image description here](https://i.stack.imgur.com/AdZdW.png)](https://i.stack.imgur.com/AdZdW.png) **WELL HERE WE ARE NOW STRONG TROPICAL STORM FORCE** [Answer] **Wing- clap.** (Slight frame-challenge.) Daron has done a splendid job of showing the calculation for *mean force and mean windspeed.* - But the dragon's not producing force continually, there's an upstroke, then a downstroke. If the up and down strokes last the same length of time, then 120~ Mph "gusts" would be generated. If a downbeat is sudden and done with full force, then that might be doubled easily knocking over any nearby soldiers and cavalry. Of course, they can just get up again. If, however, the wings are brought together in the front, back-edges meeting first, then the front tip-ends cracking together like a whip - this would result in a narrow, directed air blast and a supersonic crack proportional in magnitude to the size of the dragon's wings that executed it. Enough to deafen and disorient humans for several minutes, possibly enough to weaken and shake apart doors and other obstacles. I'm not suggesting that any damage should be done to horses here, but you could if you wanted. [Answer] If they can fly, their wings can obviously produce a force equal to their weight: 2700 pounds, which is 1224 kg and about 12240 N. If it wasn't so, they would not be able to leave the ground. And if when they grow their wings grow slightly less than their bodies, it makes sense that the adults are less able to fly than the youngsters. ]
[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. How far would we have to travel to make all of our familiar constellations unrecognisable? (in terms of human recognition)\*\* We know that groupings of stars in constellations is illusory. Two apparently close stars may be vastly distant from one another but appear to be close because they look that way in the sky. Consider FTL (faster than light travel). Suppose travellers pop out of FTL into an unknown space (perhaps because of a fault in the onboard AI). How far from Sol would they have to be in order to no longer to recognise any of the constellations? No doubt a sufficiently developed AI in our ship could orient us in relation to a suitable 3D star map but what if we were out of range of the maps? More to the point, since the AI has proved faulty, what can we recognise as humans? How far must we be away from Earth in order to recognise *none* of the familiar constellations? --- \*\***Note** I am aware that an exact answer may be difficult but I don't think the question is subjective. For example, if we found ourselves in orbit about Alnitak (which Earth dwellers say is in Orion's belt), we clearly would not see Orion's belt in our sky. However it is still possible that some other constellations would look the same at that distance. It's easy to come up with *some* distance because we could theoretically be in a different galaxy. However I'm looking for a rough *closest* distance where none of our familiar constellations would be recognisable. How can that be calculated? **To be specific** The constellations to be considered as recognisable by humans (using a telescope if necessary) is in the following list. > > Below is the list of all the 88 modern constellations recognized by > the International Astronomical Union > <https://www.constellation-guide.com/constellation-list/> > > > [Answer] Last summer, for another answer on Worldbuilding, I wrote [a script](https://github.com/HDE226868/Extraterrestrial-skies) in an attempt to show how the positions of stars in the sky would change from the perspective of an observer outside the Solar System, using data from three catalogs: the Hipparcos, Yale Bright Star and Gliese databases. (The site which generated the CSV file I used is currently down, unfortunately.) As an example, I showed what the well-known constellation Orion looks like here on Earth and what it would look like if I traveled 10 (33 light-years) parsecs in the direction of $\alpha=0$ and $\delta=0$, where $\alpha$ is right ascension and $\delta$ is declination. (I strongly suspect I made some numerical errors with the precise locations of the stars in the sky, but it seems that relative to one another, they're fairly accurate - and relative position is what's important here. The axes' scales are a bit off, so ignore the precise values for now.) Here's Orion as it looks from Earth: [![Orion as seen from Earth](https://i.stack.imgur.com/3hyPW.png)](https://i.stack.imgur.com/3hyPW.png) Here's Orion as it looks from 10 parsecs away, in the specified direction: [![Orion as seen from 10 pc away](https://i.stack.imgur.com/hREPk.png)](https://i.stack.imgur.com/hREPk.png) The constellation as a whole seems to have shifted slightly, but some stars in particular have moved more than others relative to the new constellation. For example, on Orion's belt the middle star, Alnilam, has moved away from its companions because it's further away. Mintaka and Alnitak, being closedrto Earth, have shifted more and therefore remain together. Bellatrix, too, has moved significantly because it lies only 250 light-years from Earth, much closer than any of the other stars - now it appears to be where Orion's other shoulder was, whereas that star, Betelgeuse, is off the screen. It makes sense that we'd seen changes in Orion. 10 parsecs is a few percent of the distance to some of these stars (around at least 4% for some), and given the variations in how far away they are, that does make a difference. Added to that is the fact that Orion is close to 90 degrees in the sky away from the direction we're traveling - had we moved in the direction of Orion, I'd guess there would be less distortion. To maybe quantify this a bit: Say we have a star a distance $d$ away, and we move $x$ distance in a direction perpendicular to it. For $x\ll d$, we see that it should appear to shift by an angle $$\Delta\theta\approx\frac{x}{d}$$ Therefore, the angular shift of a star twice as far away than another will be half the shift of the closer star. Therefore, we'd expect Bellatrix to move five times more than Alnilam, which is roughly five times as far away. Now let's say we're moving directly towards or away from the constellation. If the stars were all the same distance $d$ away and were separated by no more than a spatial distance $D$, the constellation would appear to have an angular size $$\alpha\approx\frac{D}{d}$$ At our new distance, $d+x$, the constellation would have a new angular size $$\alpha'\approx\frac{D}{d+x}$$ If the stars are at different distances, then their angular distances from the axis of travel will change *individually* by the above formula, with closer stars moving more and farther stars moving less. I think that Orion is somewhat representative of the changes we'd see. The constellations in the sky don't involve stars which lie terribly far away because then individual stars would be too dim! Therefore, I'll handwave a little and say that traveling, say, 50 parsecs would be enough to render *many* of the constellations in the sky unrecognizable. Constellations perpendicular to the direction of travel would be completely unrecognizable; constellations along the line of sight might still be recognizable. [Answer] Hdes answer is very thorough and essentially correct, and I am not going to duplicate their mathematics, but the flaw in their answer is the corner case of moving directly away from a constellation. Taking the southern cross as an example, the closest star is 88 light years. If I moved 88 light years away from it, the crosses angular size would halve, and it would slightly distort (as it's not a uniform plane),it would still be recognisable as a cross, just it would be half the angular size and have lost about three quarter of its brightness. The human mind would still pick it as a cross. The solution? Pick your new position carefully so that a star you've past is added to the constellation, giving it new meaning. The far side of proxima centuri is the closest place this will occur. About 4.5 light years away. The one surviving constellation will have proxima centuri added to it. [Answer] It is lucky for space travelers that they have much easier ways to find their posiitons in space than by recognizing constellations. So if you want to reduce your fictional characters to recognizing constellations, you will have to disable those superior methods, perhaps by having the ship's AI control them and thus the AI's malfunction will interfere with the automatic use of those position finders. So the human navigators will have to do everything by themselves. Posssibly that will include recognziing constellatiosn and comparing images of how they appear at the new positions with images of how they appear from Earth, and from other planets. If those images are available to them in print out form despite the AI's malfunction. If the ship's navaigational AI is on the fritze, the crew would be lucky to have a hard copy book like *Interstellar Navigation for Dummies* or *How to find Earth if Your Ship's AI is Defective*, especially if it has lots of tables and diagrams and they don't have to relyon their memories. There are a number of answers to various questions about interstellar navigation. My answer to this question: [https://worldbuilding.stackexchange.com/questions/123371/how-can-i-locate-myself-in-a-random-point-of-space/123429#123429[1]](https://worldbuilding.stackexchange.com/questions/123371/how-can-i-locate-myself-in-a-random-point-of-space/123429#123429%5B1%5D) Sugests a four step method to find one's way back to Earth if one is lost in space less than about one hundred million light years from Earth. That is a very vast distance, though only a tiny fraction of hte diameter of the observable universe. Other questions with answers about interstellar navigation include: [https://worldbuilding.stackexchange.com/questions/120255/how-can-i-know-where-to-point-my-spaceship[2]](https://worldbuilding.stackexchange.com/questions/120255/how-can-i-know-where-to-point-my-spaceship%5B2%5D) [https://worldbuilding.stackexchange.com/questions/122461/can-my-spaceship-figure-out-its-position-using-cepheid-variables[3]](https://worldbuilding.stackexchange.com/questions/122461/can-my-spaceship-figure-out-its-position-using-cepheid-variables%5B3%5D) [https://worldbuilding.stackexchange.com/questions/154851/how-to-figure-out-that-you-traveled-570-million-years-into-the-future-while-in-s/155926#155926[4]](https://worldbuilding.stackexchange.com/questions/154851/how-to-figure-out-that-you-traveled-570-million-years-into-the-future-while-in-s/155926#155926%5B4%5D) [https://worldbuilding.stackexchange.com/questions/83817/how-would-an-astronaut-conclude-hes-on-earth-but-600-million-years-in-the-futu/83879#83879[5]](https://worldbuilding.stackexchange.com/questions/83817/how-would-an-astronaut-conclude-hes-on-earth-but-600-million-years-in-the-futu/83879#83879%5B5%5D) [https://worldbuilding.stackexchange.com/questions/141867/how-to-get-directions-in-deep-space/141964#141964[6]](https://worldbuilding.stackexchange.com/questions/141867/how-to-get-directions-in-deep-space/141964#141964%5B6%5D) And many others. I note that when it comes to recognizing constellations, one of the most recognizable from Earth is Orion. The bright stars in Orion happen to be in about the opposite direction from the galactic core as seen from Earth. So if someone is lost in space and trying to find constellations, the first thing they might do is look in the difection opposite the galactic center to see if they can recognize Orion. If they can recognzie Orion they will know that they are close to Earth. And undoubtably someone more familiar with astronomy could point out the asterism or constellation which would be recognizable fromt eh greatest distance. ]
[Question] [ In designing a hard magic system, I would like to keep things consistent with the laws of thermodynamics (as many do) since, if I don't, I fear I may accidentally create a way for mages to create infinite energy. Also because our intuitions about how energy work are, whether or not people realise, heavily based on these laws. They're fairly intuitive since we live in a world where their effects are constantly observable. I imagined a system where there is some 'Aether' field from which a mage draws energy. They have some personal 'stock' which is spent when they cast a spell. There is a standard energy conversion: 'magical' into 'physical (whether that be thermal, kinetic, electrical etc...) Standard stuff. Originally, I was planning on having the mages power regenerate over time. They just kind of absorb this energy to refill their 'stock' over time. However, this energy is itself analogous to thermal energy. When talking thermodynamics, the 2nd law states that energy cannot spontaneously flow from a cool body to a hotter body. So, using the analogy between this magical energy and thermal energy (both are a scalar field), the mage would at some point be a hotter body and therefore no more energy would flow into them. I suppose I could fix this by saying that the mage's energy reaches an equilibrium with the rest of the magic energy field. As far as I can tell, this would solve the problem but I wanted more experienced mages to have a larger 'stock' than their less experienced peers. The main questions: Are there any other similar solutions to this problem? How can mages fill up on energy from some magical source that doesn't break these rules? Am I mistaken in saying that my system breaks thermodynamics? By the way, I have studied a bit of physics and mathematics. I'm not too scared of equations. Cheers. [Answer] # The boring answer: mass-energy equivalence You have seen this forumla before: $E=mc^2$ This is not the work Einstein got the most **scientific** recognition for, but it exists in the popular consciousness. This is the *mass-energy equivalence forumla*. Simply put: energy can become matter, matter become energy. This forumla tells us how much of each we get from the other. * *E* is energy in joules (1 kcal = 4134 J, 1 kWh = 3.6 million J). * *m* is mass in kg The interesting bit — for you — is that *c*, which is the speed of light in vacuum... ~300 000 000 m/s. Square that... and you have a **big number**. So from 1 kg of matter, you get 90 million billion joules, or... ## The entire energy output of a nuclear reactor for one year Mass turns into a **lot** of energy. So if you want to maintain the laws of thermodynamic while at the same time giving your wizards the capacity to output lots of energy... the answer is: they get it by converting mass into energy. Now this opens up an entirely different can of worms but you wanted magic, which — in the spirit of Arthur C. Clarke — is just: very advanced tech we just do not know how it works yet. The magic in this case is: some individuals can make energy out of matter without using a nucelar reactor. [Answer] **Concept** It could be done like [vapor-compression refrigeration](https://upload.wikimedia.org/wikipedia/commons/5/5d/Refrigeration.png). So, magic is in the aether (analogous to the hot air). Your mage captures magic by means of some mediating substance, which doesn't necessarily have to be physical, but it has to be channeled in order to expose it to the aether, or else the aether has to be channeled to expose it to the substance (analogous to the coolant). The mediating substance absorbs the aether and changes phase after having absorbed enough of it. The mage then "recondenses" the mediating substance to its original form, releasing the magic back into the wild at a destination of his choosing, and it would just happen to be the case that "condensing" the mediating substance also converts some of the aether into actual energy in some manner. Pumping and condensing the mediating substance uses energy from somewhere (analogous to the electricity driving your AC). So, here's an example of how this might work out: **Example** The mage activates his magic staff, creating a large dream-catcher-like glowing circle in the air. He's spent years training himself to use the energy stored in his body to pump aether through this circle. The circle is a window into the magical realm contained in the staff. As the aether flows into it, the magical properties of the staff are transformed from their inert state to a more energetic state, and the staff becomes visibly more powerful (if it's an organic staff, maybe it grows leaves or something; if it's a metal staff, maybe it glows). As he does this, the aether concentration in the environment is diminished significantly, but it will replenish with some time, and it never seems to be completely gone from any one place. An experienced and well practiced mage is capable of channeling aether into his magic devices more efficiently, but some mages are just naturally better at it than others. It's like being a good runner; it's a muscle you exercise. Later on, the mage once again utilizes his personal strength to catalyze the return of the staff's inner components to their inert state. This results in the aether being re-released in whatever form the staff is designed to do so. So, if it's a staff of fireball, the aether is converted into explosive energy in the real world, and some aether is lost back into the wild as part of the reaction. If it's a staff of ice, then perhaps the mediating material is such that a "condensation" reaction has to absorb heat energy in order to occur, and so much more aether is released into the wild at the expense of actual energy. It doesn't have to be a staff, though. It can be a physical part of your body that you just don't use often. It could be part of your brain, or your hands, or your clothing. However you like. **Supplementary** Now, here's the thing. You've just converted aether into real energy (or v.v.) during that last step, so you've got to have a rule for conversion to or from aether. Maybe: * E=mc2 (energy to matter) * a=Ec2 (aether to energy) So a small nuclear fission reaction converts a small amount of matter into a large amount of energy. And when mediating substances change state, it converts a large amount of aether into a small amount of energy. You might supplement this by supposing that aether is produced in the heart of black holes or antimatter stars or something like that. Maybe it's very abundant; maybe not. Well that was fun. I hope this helps! [Answer] Definitions: I will use the term "mana" as magic as in "magical energy", and "spells" as magic as in "to cast magic", to distinguish "magic" from "magic". I would suggest mana would regenerate the same way we "regenerate" our energy IRL. The earth loses a lot of energy by infrared radiation, and even the energy that doesn't leave the earth, is "used up" - if you have a hot thing and a cold thing (e.g. steam & cold water), you can use that to generate energy, but at the end, the hot and cold are both lukewarm, and although the energy is still there, you can't get any useful work out of it, unless you add energy from outside (e.g. coal). While there is a certain amount of usable energy "on earth" naturally (uranium for Nuclear Power), most of our energy comes from the sun, which is then stored temporarily in different forms, which we can unlock - solar is the most obvious from this description, but wind is indirect solar, as are sugars (which we get from plants, who generate it using solar energy), oil & coal (indirectly from solar, then concentrated). None of these contradict thermodynamics - if your "system" is earth, then energy is coming in from outside the earth; if your "system" is the sun, then the energy in the system is running down - the sun has a limited lifespan, and the energy in the sun (a nuclear reactor!) is being used up. When it's gone, it's gone. This gives you a lot to work with, I think - there's a source of mana, which is very difficult to affect, and any effect will both cover the entire globe (not just one wizard/witch), and is likely to be dangerous, so manipulating this is not a good idea. Direct use of the mana from it's source is limited (equivalent of solar panels) but ever-present (allowing a wizard with no resources at all to gradually gain mana little-by-little, at a speed for you to decide), but mana may naturally collected in various forms (easy to tweak the details to suit) which may be exploited. When a certain amount of mana collected in one place, it might trigger "ambient spells" or "natural spells" without the presence of a spellcaster, using up the mana before it could collect too much; this might be inhibited by some sort of anti-spell substance or condition. In places where the anti-spell substance exists, mana would collect in greater amounts, until it reached enough mana to overcome, causing larger ambient spells, or "mana explosions". If such an area is discovered before the explosions, there would be a lot of mana to be harvested. Ambient spells would be unpredictable, but I would expect that your easiest spells would be the ones most likely to occur as ambient. Environment & amount of mana would also affect which spells happen. With nothing inhibiting the spells, there might be a continuous spell which does almost nothing - perhaps a slight feeling of euphoria, consistent good or bad luck, specific weather, time running imperceptably faster, slower, irregularly, and so forth. Sufficiently large deposits of anti-spell ore might cause explosions, unicorns, an impassible wall, or anything else that can be caused intentionally by a wizard. [Answer] Hello from the physics SE. Since nobody has actually addressed any thermodynamic principles here, I will chip in an answer. Unfortunately, we probably need a bit of a primer first: ### Low entropy, *not* high energy, is the quantity of value There are dense sources of energy all around us. For example: $$ \begin{array}{l|c|c} & \text{Energy Density} & \text{Joules / kilogram} \\ \hline \text{Thermal Energy} (300K) & k\_B T / \text{atom} & 2.4 \times 10^5 \\ \text{Chemical Energy (max)} & 13.6\text{eV}/\text{atom} & 5.2 \times 10^7 \\ \text{Nuclear Binding Energy (average) } & 6\text{MeV}/\text{nucleon} & 5.7 \times 10^{14} \\ \text{Rest Energy} & c^2 & 9.0 \times 10^{17} \\ \end{array} $$ In order to do any work, it is not enough to have a source of energy; that energy must be from a *low entropy source*. The definition of (classical thermodynamic) entropy is: $$ \Delta S = \frac{\Delta Q}{T}$$ Where $\Delta S$ is the change in entropy of a system at temperature $T$ when it gains heat energy $\Delta Q$. Now, it is an observational fact that, for any *closed* system, the total entropy of the system will never decrease: $$ \Delta S \geq 0 $$ This is the 2nd law of thermodynamics. Along with conservation of energy, we can work out what the requirements will be for a magical effect to be consistent with those two laws: [![engine diagram](https://i.stack.imgur.com/FgvH6.png)](https://i.stack.imgur.com/FgvH6.png) Assume the magician $M$ can pull energy from the magical aether (denoted $\Delta Q\_H$), and can then use that energy to do some amount of useful work (denoted $W$), along with any waste heat produced in the process ($\Delta Q\_C$). To be consistent with the 2nd law, *any* magical process must produce *some* waste heat. If we take our closed system as the Earth plus the magical Aether, then conservation of energy requires: $$ \Delta Q\_H + \Delta Q\_C + W = 0 $$ and the second law requires: $$ \Delta S\_{\text{Aether}} + \Delta S\_{\text{Earth}} \geq 0 $$ We can combine these two equations to find requirements on the waste heat $\Delta Q\_C$: $$ \begin{array}{l} \frac{\Delta Q\_H}{T\_H} + \frac{ \Delta Q\_C }{T\_C} \geq 0 \\ \frac{-\Delta Q\_C - W}{T\_H} + \frac{ \Delta Q\_C }{T\_C} \geq 0 \\ \Delta Q\_C ( \frac{T\_H - T\_C}{T\_C T\_H} ) \geq \frac{W}{T\_H} \\ \Delta Q\_C \geq \frac{T\_C}{T\_H - T\_C} W \end{array} $$ If we take Earth's ambient temperature to be $T\_C = 300 \text{K}$ and the magical aether to be something equivalent to sunlight (but perhaps much more energy dense and available 24-hours) then $T\_H = 5000\text{K}$. Based on these values, then a magical effect which uses energy $W$ must produce a minimum waste heat of: $$ Q\_{\text{waste}} \geq 0.064 W $$ or roughly 6% of the magical effect. ### Example magical effects using this system: ### 1. Bringing mom back If you want to raise someone from the dead in the style of the Elric brothers from *Full Metal Alchemist*, then you start with the base elements (carbon, nitrogen, oxygen, calcium, etc.). All your magic has to do from a thermodynamic standpoint is provide the energy in the chemical bonds. Using my estimate $5.2\times10^7$ J/kg of chemical energy, then for a 70kg person you need to produce $3.7\times10^9$J of work and $2.3\times10^8$J of waste heat. Water boils at a rate of $2.72\times10^{6}$J/kg. That waste heat is enough to flash-boil 189 pounds (85kg) of water, roughly a bath-tub full. (If there are any suits of armor around, avoid the temptation of putting the heat there. ) ### 2. Turning lead into gold Turning lead into gold would require separating up the protons and neutrons in a lead atom and rearranging them into gold. We get a some energy from the lead, but gold has more binding energy and so we will need to provide a net energy: $$ \begin{array}{l|c|c} & \text{Lead} & \text{Gold} \\ \hline \text{atomic mass} & 207.2 & 196.96 \\ \text{Atomic Number} & 82 & 79 \\ \text{Nucleon Count} & 207 & 197\\ \text{Binding Energy per atom (J)} & 1.95\times10^{-10} & 2.19\times10^{-10}\\ \text{Binding Energy per kg (J/kg)} & 5.67\times10^{14} & 6.70\times 10^{14} \\ \end{array} $$ The difference in binding energy per kg is what the magician will need to provide so $W = 1.03\times10^{14}$J and the waste heat is $Q\_C = 6.6\times10^{12}$J. Converting that waste heat to an equivalent amount of boiled water would be 2,410,000 kilograms, or almost exactly one olympic sized swimming pool, per kilogram of converted material. ### 3. I cast *fireball* The standard *Dungeons and Dragons* fireball spell is a *non-concussive* (there's no explosion) sphere of fire 20-feet in radius. A 20-ft radius sphere has 1241 cubic meters. Air has a density of 1kg/m^3 so we can estimate the mass of the fireball to be 1241 kilograms. Then using the average thermal energy of matter at $3000K$ (10 times the value in the chart above) to be $2.4\times10^6$ J/kg, the fireball has approximately $3.03\times10^9$ Joules. Since there is no explosion, the work done in this case is *zero*. In this case, *all* the energy is spent as waste heat; put another way, the waste heat was the desired effect. ### Conclusions Having you magical effects obey the 2nd law means they must produce waste heat. However it's up to the mage *where* the waste heat is created. This could be a useful byproduct in a war-setting. However, having to fart a fireball every time the magician wants to heal someone is problematic. I suggest differentiating the skills of your magicians at least by: 1. How much magical energy they can draw in a given time; some effects may just be too large for the novice magician. 2. How skillfully they handle the waste heat. This could be as simple as dissipating it into the ground or some other nearby heatsink, or more complicated if indoors and other exotic settings. It will be up to you how much of a hinderance waste heat is. [Answer] One possibility is that only certain physical structures in the body are capable of storing magical energy, or capable of storing it in some useful way. These structures are "exercised" by the use of magic, making them grow or develop to be more efficient, like a muscle. Although the energy is still in equilibrium, more of it is accessible to the user's power, either because it's channeled more efficiently or because more of them is capable of being tapped into. This also provides an out for the traditional "some people just don't have magic, some are weaker, some are stronger", if you want that: clearly people just have better or worse genes for magic organelles in their family. [Answer] I would visualize the Aether Field as a tablecloth laying flat, and individual people could be represented as rings laying on that cloth. A person without magical talent only "contains" Aether at the same density as exists outside them; the tablecloth is flat both inside and outside the ring. They cannot do work with the Aether in this manner. A mage, however, has to actively *pull* the Aether into their bodies, in the same way that a hand could tug the tablecloth up through the ring. The cost of this is the muscle energy required to pull the tablecloth upward. Similarly, the balancing factor of a mage is that their body must expend calories to actively draw the Aether into them, increasing its density within their bodies/souls/minds relatively to the background Aether Field. This allows them to do work with it. For greater narrative flexibility, you a mage might be able to expend some of themselves (such as blood or body fat) to forcibly draw a large amount of Aether into themselves at once, rather than let it accumulate over time automatically (their body could burn the calories automatically, the same way it does to fuel their heart and brain, for example). Skill and experience could still determine how efficient a mage is at drawing in or expending the Aether, as well as how much they can store. [Answer] The system you talk about already has a parallel in the real world. Temperature. Humans frequently live in areas where the ambient temperature is lower than their body temperature, and yet we don't all freeze to death. That's because we're warm blooded, we generate our own temperature. This doesn't break the laws of thermodynamics because it doesn't come from nowhere, it is generated by our bodies through the consumption of calories. So what if your mages do absorb mana from their surroundings but only to the base level of the area. In more magic rich areas this base will be higher, in magic poor areas it will be lower. On top of this mages generate mana themselves, constantly. Either through the consumption of normal food or through some kind of magical substance which contains mana as energy, just as we generate heat. Above the base level of magic mages lose mana as well so the generate it so the two rates balance each other out to a degree. [Answer] **Reverse the way magic is utilized** Mages don't actually expend magic, they manipulate the aether field. Instead of storing the magic within their bodies, they expell it, and utilize the now different concentrations of magic in the local aether field to conjure their spells. [Answer] Your problem, as it understand it, is analogous to the problem of heating a house (bringing the house above average temperature). **A magic potion** may be considered a chemical store of energy in a form that only mages can successfully metabolize to magical energy (normal people metabolize it as sugar or not at all) - this would be the analogue to a stove-solution to the house-heating problem. Smaller scale analogues may include the kind of heating pillow that uses the heat(or magic...) of crystallisation of some medium (and later has to be re-heated/magiced). Mages may be able to expend some (usual) energy on **concentrating the ambient magic potential** into themselves, analogous to a heat pump - as you have to place magic into the conversion diagrams anyways if you want it to be part of the physical world, you can as well include a ways to mirror the pV=kNT (pressure times Volume equals Temperature times a constant) of the real world, or extend it - pVM =TNk ? So under some circumstances it may be possible to locally raise the Magic by lowering the surrounding ambient Magic, with some inefficiencies that explain the lightshow and the inability of mages to operate in stuffy armor. Ambient Magic then later refills along the gradient. If there is a conversion between Magic and any form of physical energy, you have to consider the that there usually is no going back - any matter or non-thermal form of energy is just a waystation en route to thermal energy. So either the Magic potential is constantly degrading since the Beginning, or you have to have a natural process that **keeps up the ambient** (Could be something cool like UV in the absence of certain longer wavelengths interacting with high-conductance metal that can absorb UV aka moonlight on slilver). [Answer] Do it in the same way life manages to exist without violating the second law of thermodynamics. As long as your magic system follows conservation of energy (and preferably has some inefficiency), then you can draw that energy from anywhere. To give an example, the momenta of particles. Assume our magic user can transfer momentum between particles (without creating or destroying energy, and with an inefficiency). Say our magic user wishes to increase the temperature of a room. He can use the momentum of the gas in the room, supplemented with environmental momentum to account for the inefficiency and for an increase, to change the air's momenta and increase it. The room heats up. However, this is not a loss of entropy. While on the local scale, the room has lost entropy, it is not a closed system and global entropy, as a result of the environmental energy concentrated in the room, must increase. It is analogous to life. To maintain life, and as evolution has dictated, decrease local entropy, we must draw energy from the external environment, specifically the sun. While on earth, local entropy has decreased, on a global scale of the universe, entropy must have increased. ]
[Question] [ An infinitely long cylinder, made of planetary matter with an average radius roughly equivalent to the average distance Earth's equator has to its center, orbits around a parallel, infinitely long cylinder made of solar matter with an average radius roughly equivalent to the average radius of Earth's sun, Sol. The 'planet' has an orbit similar to Earth's with regard to distance and shape from the 'sun'. This arrangement is called Cylinder World. What is a creative way to bestow the 'planet' in Cylinder with seasons? I would especially enjoy a scenario in which different lengths of the planet experience different seasons simultaneously. The 'sun' and 'planet' must remain cylinders and must remain parallel. EDIT: The 'planet' rotates about its length to produce a day-night cycle similar to Earth's. [Answer] *To avoid too much confusion I am going to state some of my assumptions. I had to edit my answer slightly, to take into account some factors I had realised over the few hours since I posted my original answer. If people don't agree, I can always roll back. I still hold by my answer, although I do think altitude will actually be the biggest factor affecting your temperatures and hence seasons.* When I first pictured the situation, I assumed that your infinitely long planet was infinite along what we would consider the width, or East/West equator, of a normal planet. The North/South radius of the planet being normal dimensions. This results in your planet being infinitely wide with Earth-like cylindrical radius. I use the term *latitude* to talk about regions *North* and *South* from the central *equator* (which is the *horizontal* cylindrical latitude that is the receiving the most sunlight). There would be no frozen polar latitudes and you will have to adjust the typical North/South magnetosphere (if your planet even has one). For a day/night sequence your infinitely long parallel planet has to be rotating on it's infinite East/West axis, with the infinitely long sun on one side. Like a rotissary chicken. This daily rotation is always in the same direction, like a normal planet. Sunrise and sunset would be on the N/S poles rather than E/W equator of a normal planet (which in your situation is infinitely wide). There would not be any latitude on your planet that had a different amount of sunlight over the day due to an axial tilt, which is responsible for the seasons. Your parallel planet does not have an axial tilt, hence your trouble figuring out the seasons. To get around this you need to add another component to your parallel planet. You can add a stationary twisted feature along the length of your cylindrical planet. The tightness and height of the twist is up to you, which would affect the *concentration* and duration of the cooler lee shadows. **The twist doesn't bring the planet as a whole any closer to the sun along it's infinite width but rather just twisted regions of it along the cylinder.** Image taken from [ScienceDirect](https://www.sciencedirect.com/science/article/pii/S0045793016302134) ![enter image description here](https://i.stack.imgur.com/iJVwM.jpg) So the 'north' region is twisted closer to the sun while the 'south' is twisted away. This provides different bands of altitudes, and 'shadow areas'. As the planet rotates, each side of the twist would receive the same amount of sunlight through the day. Just always at different *times* of day. Depending on which way your planet rotated, one side of the twist would always receive more morning sunlight and then be in shadow for the rest of the day. So you have day/night, various altitudes and temperatures but still equal amounts of sunlight, just at alternating times over the day. So how to get 'seasonal' variation? To try work around this, you can add an oscillating twist feature along your cylindrical planet. So the 'north' region twists closer to the sun while the 'south' twists away for one cooler 'season'. Then it untwists and equalizes providing a neutral warmer 'season' before twisting in the other direction providing a new different cooler 'season'. This oscillating twist would take months to work itself through the cycle, providing different seasons where regions receive more morning sunlight and then later in the year more afternoon sunlight, as well as periods with more variation in altitude separated by a periods with a flatter neutral terrain. It would not be as extreme as a typical planet but would be noticeable to some extent. Especially if you had additional rugged topography on top of the 'twist' features, which provided further shadow effects. These seasons would not be like a typical planets. Those areas within the leeward shadow of the twist will also be cooler than those areas on the sunlight side. Due to the effects of altitude on temperature, higher regions that are much closer to the sun could have a cooler season than those further away from the sun. When these two facts combine, I think your seasons will have a 'banded' nature. As these twists work themselves in and out, they will result in pockets of isolated regions experiencing different seasonal conditions at the same time of day along the same latitude (as you requested in your question). The height and tightness of the twist affecting the extremes. You can see the 'contours' on the image provided earlier. The more twisted the planet is, the more areas of cooler altitude. **Solar:** If you couple this oscillating planetary twist feature with a similar solar twisted feature then you could have more extreme variations in your seasonal conditions. It's more likely that your planetary dynamics of different objects, eg sun and earth, would have the same features working on them with different timescales. The solar twist would be considerably slower and take 100's to 1000's of years to complete. This slower solar twist could give you changing conditions similar to the aphelion and perihelion cycles. Those lengths of the planet that are furtherest away (aphelion) could be experiencing the equilivant of more extreme winters than I described above and those closer (perihelion) could be having more summerish conditions. Again this would be banded, and leave isolated pockets on your planet experiencing different conditions along the same latitude. Some regions having a milder winters and summers while others are having stonger winters and summers. \*\*As noted by other answers, you may need to move the planet's orbit a bit further away from the infinite sun. It would be a bright beam of light running across the entire length of the sky and not just an isolated disk. fyi: This would involve your planet crust and mantle being more 'malleable' than a normal planet consistency. However, you have an infinitely long world orbiting an infinitely long sun while always being parallel to each other. You can work in some malleable planetary physics. :) [Answer] EDIT: Okay, how about this... [![enter image description here](https://i.stack.imgur.com/aORjR.jpg)](https://i.stack.imgur.com/aORjR.jpg) ***Original answer below...*** [![enter image description here](https://i.stack.imgur.com/F0ZGg.jpg)](https://i.stack.imgur.com/F0ZGg.jpg) ...Basically the cylinder that is the sun goes wider than the cylinder that is the planet. Both still cylinders. As for day night cycles Larry Niven solved that problem in Ringworld. I don't like his solution, but it works. Check it out. [Answer] The planet's orbit around its sun is strongly elliptical. When it's farther away, it gets cold enough to be winter and when it is near then it is summer. [Answer] An infinite Cylindrical Moon (CM) would do. This Moon would behave differently from our own. * When it is between Cylindrical Earth (CE) and Cylindrical Sun (CS), it is winter, for this is when the least amount of light will reach CE. * As CM moves away to unblock sunlight from CE, spring starts. CE gets increasingly more light. * At some point, CM starts reflecting light towards CE, which then gets a summer. The summer peaks when CM is full. * As CM wanes, autumn/fall begins. This autumn, however, is more like a milder summer. * When CM starts coming out of CE's shadow (thus waxing for the second time in its cycle), temperatures rise. This is the second summer in the cycle. * When CM stops reflecting light towards CE, a second spring happens. Compared to the first one, this one is in reverse. * CM finally starts blocking sunlight again, closing the cycle with another winter. Notice that CM does not have to be constrained by the same lunation period and apparent size in the sky as our own round Moon. It may have a longer lunation, and a smaller apparent size... This way, it will never cause an eclipse, thus there is no eternal night during the New Moon phase. [Answer] Perhaps the solar cylinder has variable brightness, with hot and cold areas evenly separated and moving along its length at a constant speed. Parts of the planetary cylinder that are currently near a hot patch will experience summer, while other parts near a cold patch will experience winter. [Answer] Lets say north and south are along the length of the cylinder, and east and west are around it. Standing on the planet, looking east and west would look just like earth, with the horizon dropping off a few miles out at sea level. Looking to the north or south, though, you would see triangles angling out to a single point. From above, the infinite line of the sun would stretch out out to that same point. Looking east at dawn, you would see the line of the sun suddenly emerge from the entire horizon at once, before proceeding on it's daily arc overhead. On Earth, the sun takes up about 0.5 degrees horizontally. This sun would take up 180 degrees. If it puts out similar energy per surface area, this means it would have to be about 300 times smaller vertically to avoid roasting the planet, or about 6 arcseconds. This is incredibly small--it would be the same size as a 6cm diameter cable viewed from a distance of 2kms. Still, it is about 8 times larger than the largest stars, so with how bright it is, it would still be quite visible (but not so tough to stare at, since you could only see a portion of it at a time). On this world, gravity would have to not act in one of the 3 dimensions (along the length of the cylinders), or you would be spaghettified by the infinite mass at either end of you. The distance between the sun and planet would always be the same along the entire length (definition of parallel), so if the sun was uniform, then although there would be a night/day cycle, then all parts of the world would go through the same seasons at the same time, as the cylinder moves in an eliptical orbit closer and further from the sun at all points at once. And all parts of the world would have an identical climate. The only way to have different seasons is if the sun grows hotter and colder at different points along its length. Places below the cold spot would shift to winter, then back to summer when it warms up. Or the hot and cold spots could be fixed, and the sun could be moving lengthwise relative to the planet. In this case, if you heard word that the people north of you just had a long hard winter, you know that you're getting that long cold spot next. ]
[Question] [ I'm heavily ignorant when it comes to mathematics and just science in general, but I have thought of four habitable planets, all of them revolving around a K-type sun. They're all colonized by humans, and i'm trying to come up with the geography and size of each planet. I would love it if anyone could look at what I have written and correct me, as well as fill in blanks on what they think my planets would look like or have. I'll write them in order from closest to the sun to farthest. Currently I have not thought of moons. **Labita**: In size, it's small, the smallest planet currently. I'd say a mass and radius directly similar to Earth. Labita's surface is 64% water. **Vir**: Slightly bigger than Labita. It has a surface that's 72% water. **Mena**: Surface is 60% water. smaller than Vir, but bigger than Labita. **Kaldreer**: A [superhabitable](https://en.wikipedia.org/wiki/Superhabitable_planet) (large with heavy gravity) planet. I'd say it's surface has at most 77% water. Warm, and a thicker atmosphere. My first concern is the orbit. I would say they would mimic our own solar system's orbit, but I don't know how far away they would all have to be to not collide, and if the distance they'll be from the sun is safe enough. My second concern is their size. I know I definitely made some mistakes, but I know for certain that I want Labita to be the smallest, then Mena, then Vire, then Kaldreer. I want Kaldreer to be significantly bigger than Labita, but not too big that it would unsafe for human life. How big and how small can I make Kaldreer and Labita before it's unsafe? (Update: would it be too far of a stretch to propose the idea that Labita and Kaldreer would orbit around eachother instead?) Thanks to anyone who decides to read and help me. [Answer] First -- K stars are just a little redder and fainter than the Sun. There is no problem having rocky planets in the habitable zone. And the habitable zone can fit as many planets as around other stars (see here for details: <https://planetplanet.net/2014/05/19/building-the-ultimate-solar-system-part-1-choosing-the-right-star/>). Second -- there is no issue having 4 planets in the habitable zone. The inner edge for an Earth-like planet is reasonably well-defined as being at about 0.9-0.95 AU (for Sun-like stars, can be adjusted with a simple scaling factor for fainter/brighter stars), but the outer edge is extremely fuzzy and can extend out almost indefinitely. This is just because it's easier to provide energy to a planet's surface (e.g., through a thick atmosphere that retains heat) than to cool it off very fast. Third -- in terms of orbital spacing, you can easily fit 4 planets in the habitable zone. Earth and Venus are relatively closely spaced (semimajor axis ratio of 1.4, orbital period ratio of about 1.7). If you take a look at systems with small (presumably rocky) planets around other stars, they tend to be as close to each other (or closer than) the Earth-Venus separation. This plot shows some Kepler candidate planets (all smaller than 1.5 Earth radii). The x axis is logarithmic, so the distance between planets depends on the orbital ratios (not the absolute differences). I included a shrunk-down Solar System as comparison (the separations are preserved in the shrinking): [![from paper downloadable here: https://arxiv.org/abs/1312.1689](https://i.stack.imgur.com/JAa5p.jpg)](https://i.stack.imgur.com/JAa5p.jpg) Four planets with the Earth-Venus ratio, starting at Earth's distance, puts the outermost one at about 2.7 AU. With a slightly closer spacing (say, 1.3 in separation), the fourth planet would be at 2.2 AU. This is close to the edge of the "traditional" habitable zone -- if the planet has a modestly-thick atmosphere of something like CO2 or even H2 then it can retain liquid water on its surface. Fourth -- I did a series of blog posts a while back explaining how to choose stars, planets, and orbits when building a planetary system. It's summarized here (with links to the different posts): <https://planetplanet.net/the-ultimate-solar-system/> Finally -- just to counter any criticisms on these points, I am an astrophysicist working on exactly this type of question (specifically, on planet formation and orbital dynamics). [Answer] # What is a K-type sun? Alpha Centauri B (K1V) and Epsilon Indi (K5V) are both K-type. Really the only important value to this question is luminosity. Alpha Centauri B's is 0.5 $L\_{sol}$, and Epsilon Indi's is 0.22 $L\_{sol}$. Since we want four planets in the habitable region, we have to have the biggest habitable zone and brightest sun, so we will use 0.5 $L\_{sol}$. # How big is the habitable zone? This is something of an open question in our own solar system. There are [many estimates](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Solar_System_estimates). I'm going to go with the range of 0.75 AU to 2.25 AU, since that is easy for calculation. We can use the inverse square law to adjust this for our slightly less luminous star. The change in distance is the square root of the change in luminosity, so your planets will be distributed evenly at 0.53, 0.88, 1.24, and 1.59 AU from the planet. # Can I fit four planets in there? I ran a simulation with your worlds in [Rebound](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Solar_System_estimates) using Python. I have my setup on github if you want to [take a look at it](http://onlinelibrary.wiley.com/doi/10.1029/2010GL045777/pdf). The file is ``` orbit_apcthx_171218.py ``` The initial conditions are set with Alpha Centauri's mass (0.907 $M\_{sol}$) and the four planets as given above. Since you didn't really give masses, I set their masses each to Earth's The results are graphed below, with time on the x-axis, in 100 year increments and distance from the star on the y-axis. [![enter image description here](https://i.stack.imgur.com/4e0eG.png)](https://i.stack.imgur.com/4e0eG.png) The good news is that none of the planets ends up careening out into space. I kind of expected that to happen, but was able to quickly find some orbital conditions where all four planets would be stable (the key is to start them in slightly eccentric orbits). I integrated over 1 million years and the planets stayed stable (The graph is only for 100,000 years). The wavy lines are due to orbital resonances. Interestingly, at least for us orbit nerds, the planets straighten each other's orbits out, removing most of the eccentricity. The variations for each planet are about the same magnitude as the variations in Earth's orbit. Now, this does not *prove* stability by all means, but I think it is plausible to have four planets in the habitable zone of a star the size of Alpha Centauri B. # What about different sizes? I swapped up the sizes to make some comparisons. I changed planet sizes from as low as 0.1 Earth to 10 Earth's. I got stable orbital results for all size combinations I ran (though I ran shorter simulations, in this case). My findings where that a planet needed to be size of Jupiter before it started ejecting other planets from the solar system over the short term. Even a planet up to 10 times the size of Earth won't have enough gravity to put the other planets in wierd, possibly deleterious orbital resonances. That gives you a considerable margin of error for planet sizes. # Conclusion You can operate a solar system with four planets in the habitable zone. Now, it isn't necessarily clear that you can *form* a system with four rocky planets in the habitable zone, but if you use some handwaving you can claim that somewhere in the universe this setup came to be. Also, the habitable zone here is a definition stretched pretty wide. For example, the farthest planet will get 22% less sunlight than Mars, so its debatable whether that could ever be more than an icy tundra. But maybe it could be one giant frigid ocean and work well enough for your purposes. Please ask followup questions about specific planets and their atmospheric and water conditions. [Answer] I think that you have too many habitable planets in your system. In our system Venus is near the inner radius of the habitable zone and Mars is near the outer radius. Look how they turned out. I think that three habitable planets is probably the max before they get too close together to interfere with each other's orbits. You can have more habitables if one or more are moons of a gas giant. I suspect that in wanting the inhabitants to be taller on the smallest planet, you are thinking that it has to be lower gravity. That's not always the case. Just look at the range of heights of people on Earth where everyone experiences the same gravity (within reasonable measurements). As for size of the planets, I'd put the smallest one at about 80% Earth's mass to keep the rest in a reasonable range. However, mass does not have to be directly related to size. If you want the planet to be bigger, it just has less heavy elements in it (more rock, less metal and fissionables). ]
[Question] [ We all know that modern internet forum users, unlike your average social media frequenter, are skeptical and they often dismiss extraordinary claims as fabrications. We all also know that these platforms - and their cousins (imageboards, IRC rooms and the like) for that matter - often have a diverse and constantly shifting userbase, which makes it pretty much impossible to know who's really who and to assess whether anyone's aforementioned fabrications are really just that. Let's suppose that in a possibly far future, when humanity has all but abandoned their mortal bodies and uploaded their consciousness to the great net of things, criminals (actual and supposed) are punished by the government not by confining them to material boundaries but by relegating them to parts of the network where they cannot access their society anymore - that is, the past. All offenders are sent back in time to inhabit a previous incarnation of the internet without being able to influence it beyond what is allowed to a normal user of that period of time (they're still a human mind, so no brute-forcing government sites or infiltrating nuclear missile facilities). This guarantees them a sentence that cannot end with death, as the internet has never really gone down since its modern conception and it's unlikely something like that will ever happen. Now, here's the question: how would one of these offenders persuade modern (as in, early 21st century-based) internet users that they are in fact prisoners from the future and not just someone "making shit up"? Keep in mind that I'm talking about Average Joe++ here, not about a scientist or someone who has enough knowledge of undeniable future events to be able to catch the attention of this period's governments. Just your average augmented consciousness who had average "common" knowledge of his time. Not unlike a modern day non-college graduate american who would certainly not be able to prove himself to be from the future if sent to the middle ages without technological devices - who the hell memorizes the answer to Millennium Prize problems or the specific impulse of observable Quasars, right? And just giving a rundown of future technologies would probably not be enough, just think about how many speculative sites on the matter are there. **In short, what would push modern internet users, and not just a small conspiracy theory fringe group, to believe such an impossible claim?** Would a list of US presidents or notable global happenings a la Nostradamus be enough for the ever skeptical internet hivemind, considering that there's no real way to confirm beyond reasonable doubt that someone who made a claim 10 years ago on the internet is the same individual who's making another claim today? Let's assume these "criminals" manifest with an untraceable IP, or something that a first-world government itself would need to devote several million dollars to in order to crack their presumed encryption before they uncover something fishy, "I'm behind 7 proxies"-style. I may or may not be asking this for a friend who might or might not happen to be a prisoner from the future trapped inside this site. Edit: this is not duplicate of "[How do you prove you're from the future?](https://worldbuilding.stackexchange.com/questions/12348/how-do-you-prove-youre-from-the-future)", as in this question the prisoner cannot prepare beforehand or bring items with him - it's an entirely different scenario. [Answer] ## Extraordinary Claims Require Extraordinary Evidence No one will ever believe this person. Ever. (Well, no one who isn't a conspiracy theorist) The turnover rate of most forums is too high and enough of the people are going to think you're trolling them in saying you're from the future that you'd only get conspiracy theorists to maybe believe you, but even then you may be pushing it because though if you know enough information to convince someone you know future things it would have to be things we can see in a relatively short time and can verify quickly. As well, it would have to be extremely accurate. If any other time paradox or alternate universe came into being due to you getting sent back then it's impossible because if you're not almost exactly (most humans don't care about a few seconds or minutes of inaccuracy, but being more accurate helps your claim) correct, you'll be completely ignored. Then there is the fact that you could have definite proof of your claims, but people suddenly can't go back and find that proof like a forum got deleted and the posts are gone and not everything is forever on the internet especially when it comes to forums. Also, SE type sites have some methods for these types of discussions/claims, but not to the extent of your typical forum. ## Intentional Deletion by Future Authorities Maybe unbeknownst to the prisoners, the government sends back agents every so often to run interference and deletion if they actually catch enough people's eyes. I'm not talking about deleting the person (that's unethical!) but deleting their forum posts, claims, or building up the side that's calling them a troll, nutter, etc. [Answer] ## Can we actually help you? Start with an end. You made it. You convinced whole worldbuilding community that you are trapped mind from the future. Bravo. But ... Can we actually help you? Even though we as community certainly enjoy discussing hypothetical questions like "[Is it possible to build Death star with today tech?](https://worldbuilding.stackexchange.com/questions/3458/building-the-death-star-with-todays-tech)" , *no one is trying to build it* Even though we know [how to get Average Joe to power over the world](https://worldbuilding.stackexchange.com/questions/23350/could-an-average-person-take-over-the-world), *no one is trying* (Well, at least I hope so) ## Enjoy your punishment while you can Sad truth is, that even if we believe you, no one would do more than just ... post an answer, because *thats all we can do.* Sorry. ## Addendum: Things you need to know how to set you free * How *exactly* does the punishment procedure works * How to revert it using current technology. Again, exactly, step by step Imagine this. I am writing this answer on late 2015 Macbook Pro. I accidentally encrypted my hard disk **and** was sent back to year 1997. How do I unlock data on disk without knowing password using 1997 tech? It is impossible. Again, sorry. [Answer] > > Let's suppose that in a possibly far future, when humanity has all but abandoned their mortal bodies and uploaded their consciousness to the great net of things > > > Based on this sentence alone, i consider highly impossible for our Average Joe to be able to convince anyone that he is from the future. You are talking about eons or millennia into the future. Our current (21st) century will be ancient history to them. Their technology will be beyond our sci-fi theories, far beyond what we can understand right now. Reverse your example. Lets send you back in time, about 5000 years. How can you convince the people back then that you are from the future? Talk to them about the internet? About your smartphone? Can you predict the future for them? How accurately? We know nothing about that period - or at least 99.9% of our population knows nothing about them. How would they perceive your claims? The only way I consider a possibility is the ability to accurately predict the future - not everything, but major events that influence millions of people. And this requires special preparation for our Joe. Not something the average criminal is prepared for (unless of course your Joe plans exactly that). And that's the moment the paradoxes begin. So you convince the authorities tat you are from future. You give them warnings about a couple of major disasters. They consider you lunatic and ignore you. When your claims become true, they reconsider. And decide to hear your 3rd warning. They take steps to prevent a catastrophic event or reduce its casualties. Game over at this point. The future has changed in unpredictable ways. Is the time continuum the same? Has it been altered? Changed completley? [Answer] The *only* way to convince skeptics you're from the future is to make multiple, accurate, short-term predictions (recorded in a reasonably tamper-resistant form a reasonable time ahead of the event). Who won the 2019 World Series? Who won the 2019 Nobel Peace Prize? Who will be president of the USA on March 1, 2021? If a single author makes, say, a dozen predictions like this months ahead of the events, and *every single one* is accurate, there are only two reasonable possibilities: they have some kind of foreknowledge, or they're actually (successfully) manipulating the events. Either is worthy of considerable attention, and the latter seems at least as unlikely as the former. Now, convincing people you're not running the world might be difficult -- because refusing to work to order has the same result as not being in control: random stuff happens. Likewise, running everything has much the same result as foreknowledge: your predictions are accurate, over and over. The way out of this is to make predictions about things that aren't reasonably controllable: meteorite impacts (like the Chelyabinsk event), sunspot counts, gamma ray bursts, and other cosmic events. This requires a completely different knowledge set from predicting the World Series, of course, but it's not much harder to check -- and it's beyond the ability of anyone to reasonably manipulate the events (though potentially open to accusations of manipulating the *detection* of the events). [Answer] Let's try flipping the question to something more relatable: How would you convince someone from say, 1800 that you were from the future if all you could do is write letters/books? The most obvious way is to tell them of future events. However, since you don't have any preparation it would have to be events everybody knows happens, and it would really depend on how much you paid attention in school. Maybe you could tell them that them that James Madison would be president in 1808 or that the napoleonic wars were going to happen, but I have no idea how that would go. Most people would probably think you were just good at guessing future events, unless you actually knew history well enough to name specific days and years instead of general events. We can assume the same would hold true of a time traveler from the future coming back to today. They may tell us that we're going to go to war in the south china sea sometime in the 2030s, but is that really all that impressive if they don't know the specific year or date? They may even tell us who is going to be president next, but even that could just be a good guess. To get people in the past to believe you, you'd need to predict an event with sufficient serendipity - something no one could predict otherwise. For example, if you told someone that Napoleon III was going to take power in 1848, people might ascribe some sort of prescience to you, because that event was much less predictable than a lot of other historical events. In similar terms, if someone in 2000 said "Donald Trump will be president in 2016", there is some case for prescient knowledge. So one way your time traveler could convince people is by predicting historically surprising events. These are rare, but if your time traveler could reasonably say 3 or 4 completely unexpected things, then they would probably gain some following outside the fringes. However, I don't think this will be enough to convince the general public. Along these lines, another good way is to predict art and literature, since those are up to whims of individuals and can't be reasonably predicted in any other way except for prescience. For example, if I said "Jane Austen will publish a novel titled *Pride and Prejudice* in 1813", then people would either have to believe that I know Jane Austen personally or that I somehow have foreknowledge. If I predicted enough book publishing dates, then that would make a pretty convincing case that I was a time traveller. In the same way, if our hypothetical time traveler knew a few famous books and movies from the 2000s, they could make a reasonable case that they were from the future. It's important to note here that none of this knowledge actually requires specialized college education. There is nothing here that is very obscure or unknown, but a lot of it is knowledge people learn and then forget. If our time traveler was an adolescent in middle school who's memorizing dates for an exam, they'd actually have a very good chance of being able to use that knowledge to convince the public. [Answer] Rather than making event predictions, I would take the approach of disclosing discoveries. The issue with event predictions (who wins the pennant/election/war) is that you have the butterfly effect to consider. Your presence may just in a tiny way affect random events and change things. Even worse if your predictions are taken seriously, they may change the timeline in a non butterfly manner. However, if you share discoveries, than this should not be affected by your impact (butterfly or large) on the timestream. For instance, if you disclosed in 1980 that YBa2Cu3O7 was a superconductor, that would be a rather momentous thing that would be very hard to know without a lot of random trials in the field. Similarly, discoveries in other fields: archeological, geological, biological, astrologic...I mean...nomical. Note that many discoveries don't require the creation of an entire industry (as some inventions do). For a HTSC, you just need to know the formula. Boom...instant Nobel Prize with almost no work. ]
[Question] [ My setting is low-fantasy (weird stuff happens sometimes, but it's rare enough not to have a real impact on everyday life). It focuses on a specific kingdom. This kingdom is supposed to be a typical small kingdom from the middle ages. It would be something like 10,000km² big, with a standard population. The money unit is the denier (with bronze, silver, and gold deniers). 20 bronze deniers = 1 silver denier; 20 silver deniers = 1 gold denier. A peasant earns 1 bronze for a day of labor and something like a good meal at a fancy tavern costs 1 silver. The kingdom has consequential debts. What would be the total number of coins in circulation? What would be a coherent amount for these debts? What would be a plausible yearly income? [Answer] All of these numbers should be taken with a huge grain of salt, many assumptions and approximations have been made, without very detailed information about your kingdom's population and economic situation I think that's the best you can hope for. **Yearly income and debts** If one days labor nets 1 bronze, you could easily extrapolate a yearly income. 1 bronze a day **x** 6 days a week **x** 52 weeks a year **=** 312 bronze a year Also equaling 15 silver 5 bronze. So for reference giving a gold coin to a peasant is more than they are likely to earn in a year. Skilled craftsmen would obviously earn slightly more than this, as would land owners and other businessmen, but the peasants would be the majority of the population so this would be likely near the median income. The Clergy and the Monarchy would of course take their cut in tithe and taxes. These were never fixed percentages of income, but mostly fixed fines/fees but generally overall were less than 10-20% of income. So a good approximation of their incomes would be a percentage of the income of the entire kingdoms population. I'm going to make up some numbers here. Assuming a very-fertile kingdom populations could be around 10 people per square km so your kingdom would have a population of ~100,000 people. So assuming median income for 100,000 people and 10% for the king gives a royal treasury income of ~ 3,000,000 coppers = 150,000 silver = 7500 gold a year So a debtor is unlikely to loan more than the entire treasuries yearly income, especially given no collateral, but an unscrupulous royal could engage multiple lenders. So debt could potentially be several tens of thousands of gold coins **Coins** A kingdom of your size would likely not even have a mint, but would instead use coins generally in circulation or only mint lower value coins. Following the fall of Rome western Europe didn't mint gold coins for nearly 1,000 years (until the Floren in ~1200), instead using locally minted silver coins (often adulterated with copper) and gold coins from the east. There would be no exact way to know the total coinage in circulation, and precious metals would often be stored by melting them down and making them into things. Barter or other exchange good contracts would be much more common, the peasant is more likely to be paid in food than coins. The circulation would depend a lot on the economics and population of the kingdom, things like the velocity of money come in to play i.e. that peasant is likely to spend almost all of his earnings as soon as he gets them. So that peasant may only even see a few copper coins at a time and would often never have any coins. **Warning Many Assumption Again** - So 100,000 people generally only needing a few coppers a piece would give you somewhere around only 300,000 coppers total in circulation. This clearly isn't enough money to pay the king, but again barter would be more common, The royal treasury could pay with food for needed labor, or would pay functionaries by allowing them to collect the taxes or fees for a region (i.e. the city guards are paid by collecting tolls at the gates etc.) [Answer] * A substantial part of the economy would be based on barter. The serf owes the lord two weeks of work at harvest time, a fat chicken at some holy day, and so on, but **not** a set amount of money. * A substantial part of "cash savings" would be in coins or other small valuables like jewelry. Few people deal with bankers. Even more of the savings would be in real estate, tools, etc. So most people have absolutely no coins, or at best a couple of dozen hidden away under the hearth. A prosperous craftsman might have a small bag of coins. Only merchants and nobility would have chests full of coins, and there are not many of them. [Answer] The thing about commodity based currencies is that the supply isn't fixed; one of the reasons people shifted to using metal alloys instead of actual gold and silver. If say an enemy ship full of gold bullion was captured by your country's navy; if the government wants to boost the economy, it converts the bullion into coin and starts public works. The number of gold coin in the market increases, but there's not that much increase in demand for gold coins; the master mason isn't going to pay all his people in gold, he'll pay most in silver or bronze. He will, most likely, go to a goldsmith and trade a lot of the gold coins for silver and bronze coins. The goldsmith, in turn, can sit on the gold, or melt it down into stuff he can sell to the rich and get silver and bronze coins, which he can trade for the next batch of gold. On the other hand, if there's a shortage of coin in the market, the price of gold coins will rise on the limited supply, compared to the price of solid gold dinner plates (let's say). People will simply melt them down into coins for circulation. Remember, the point of a Royal Mint is that the monarch's honour guarantees that each coin is of the material and weight specified, not that no other source of coin exists. That came much later. The other issue is that the size of the economy is measured by the total value of the number of coins in circulation, and the *speed* at which they circulate. A small, isolated village may only have 40 silver and 100 bronze coins in circulation, but most of the bronze will probably change hands dozens of times in a day. Given that we know neither the population, nor the details of the economy, as in what shape is the treasury in, what are the major products, what kind of individual holdings are there, what do they need to buy from abroad, etc., it's not possible to guess at annual income; and given the circulation rate issue mentioned above, even if the number of coins were fixed, it wouldn't be possible to guess, unless the Royal Mint issued numbered coins as the only legal tender. ]
[Question] [ I have an idea for a planet that orbits two stars. These starsslowly orbit each other, have equivalent masses/sizes, and while one is slightly red, the other is slightly blue. When I talk about the color, the stars are primarily white, with slight tints, just enough to notice. A year is about as long as Earth's, and a sun cycle (day) is 24 Earth hours. The rotation of this planet causes eight hours of night time, say, from eight to four o'clock on equinoxes. One sun would rise at four o'clock and set twelve hours later, and the other would rise at eight o'clock and set twelve hours later. **Is this system possible?** I also wonder how seasons would affect the sunrises and sunsets if the planet had a tilt about the same as earth, but more important is how plausible this planetary/star system is. I'm a little bit worried about the stars, I read somewhere about red stars being smaller and blue stars being larger. [Answer] I'm afraid what you're asking for is going to be quite tricky, at least not with a universe that operates like ours. I'll try to discuss the individual issues, and then offer some suggestions on what you *can* do: ## Same mass, different color? > > ... have equivalent masses/sizes, and while one is slightly red, the other is slightly blue. > > > Stars *do* come in a wide range of colors, depending on their composition and color. For the most part, however, two stars of roughly the same mass and diameter will have virtually identical spectra (color). In fact, astronomers *use* the spectral characteristics of stars to *classify* them into categories of size and mass. For more information, the [stellar classification](https://en.wikipedia.org/wiki/Stellar_classification) page on Wikipedia gives a decent introduction, although it is somewhat technical. ## Year length and sunrise? > > A year is about as long as Earth's, and a sun cycle (day) is 24 Earth hours. [...] One sun would rise at four o'clock and set twelve hours later, and the other would rise at eight o'clock and set twelve hours later. > > > Unfortunately, this would be difficult. So-called P-type binary star systems look like this: [![enter image description here](https://i.stack.imgur.com/9lKA3.png)](https://i.stack.imgur.com/9lKA3.png) (Image mine, and obviously not to scale. The stars would be *much* closer to each other and *much much* farther away from the planet, relative to how I've drawn them, but then you wouldn't see anything.) In order to have an Earth-like year *and* be in the [Goldilocks zone](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone) around your two stellar objects, your planet would have to be quite distant from the center of the binary pair. That means that the stars are going to rise and set at very nearly the same time. In the daytime sky, they will appear very close together, overlapping much of the time. ### S-type systems There's another possible configuration for the star system: [![enter image description here](https://i.stack.imgur.com/EPGNP.png)](https://i.stack.imgur.com/EPGNP.png) For much of the year, the planet would be "in between" the stars. Unfortunately, this means extreme temperature variations (including the planet probably being burnt to a crisp), but also in near-constant daylight. It's also probable that the "orbit" would be complex and irregular, and chances would be good of the planet actually getting flung out of the solar system altogether, becoming a [rogue planet](https://en.wikipedia.org/wiki/Rogue_planet). These s-type systems are quite common, but the sunrise pattern would only hold true for a small window of time (a few months) over a large timescale (many many years, until the stars' orbits around their barycentre and the planet's season aligned again). ## Seasons > > I also wonder how seasons would affect the sunrises and sunsets if the planet had a tilt about the same as earth > > > Seasons would be pretty much the same as they are on Earth. In fact, for most practical questions concerning P-type binary star systems, it's helpful to think of the two stars as a single mass whose center is the center of the solar system. *All other things equal,* the orbits, effective gravity, and radiation (light, heat) aren't significantly different from what we experience in our own solar system. With S-type systems, it is of course more complicated. The orbital periods for the stars can vary widely, while the Earth-like years for the planet would result in relatively normal seasons *most* of the time, however things can get exotic in a hurry if the planet's orbit (nearly) intersects the non-bound star's orbit. At best, you'll see an *extremely* hot summer. At worst, the planet's orbit will be radically changed, or the planet will be thrown out of the system altogether, sending its inhabitants into the coldest winter on record... Of course if one or both of the stars are significantly different (i.e., something off of the [main sequence](https://en.wikipedia.org/wiki/Main_sequence)), that's where you can start to get some different effects without crazy orbital mechanics, but that's only because the color, temperature, radiation, mass, etc. would be different—nothing to do with it being part of a binary system. I'll talk about this a bit more in the next section. ## How to make it work 1. **Different types of stars.** Stars of different sizes, or at different points in their life cycles. They are never going to be *very* different, visually (to the unaided eye, stars mainly just look *bright),* so the most striking difference you're likely to get would be if you have stars of different sizes. 2. **Multiple sunrises,** I don't know. To make that work, the planet would have to be so close every living thing would be burnt to a crisp. However, there are many things you can do creatively with a binary star system: you have two different points of light in the sky, you can have partial solar eclipses, different "**suns**-worshiping" religions, twice as many solar flares wreaking havoc with electronic equipment, opportunities for divergent scientific history (it would be easier for early astronomers to figure out that the stars are orbiting a common point in the sky, so perhaps the [heliocentric model](https://en.wikipedia.org/wiki/Heliocentrism) could be proven much earlier than it was on Earth). [Answer] **Sort of** You can have 2 stars, and you can have one rise 4 hours after the other. Just stick your planet in the L4 or L5 Lagrangian point of your binary star system. This is stable over large time-scales and puts the stars 60 apart, which gives you a 4 hour gap between sunrises (assuming a 24 hour day). **Sounds good. What's missing?** Those Lagrange points are only stable if your central star is at least 25 times more massive than the other one. It's going to be a lot brighter. [Answer] I think it could work (roughly) as long as we can cheat on the mass. First, use a binary system where your planet orbits a midsize, red dwarf star, which would supply some of your light (at well under 1 AU) while a hot star with maybe 1.5 solar masses orbits as a few AU (the two stars orbit around each other, while your planet orbits the red star). Assuming you aren't tidally locked to the red star, as you orbit each star would spend (up to) 12 hours from sunrise to sunset (though the exact times would vary by time of year). If you balance the orbits right, each star would appear at close to the same size. For instance, consider the scenario (it's close, but there are better combinations): You orbit a red dwarf star of mass 0.5 solar masses at a distance of 0.35 AU. You might or might not be tidally-locked at that distance, so we can just apply handwavium and say you aren't. There is a hot F-type star with 1.5 solar masses at a distance of about 3.2 AU. That would be a yellow-white star. You would get about almost exactly half of your heat/energy from each star (each would supply 1/2 solar radiance). This is because the hotter star is about 80 times as luminous as the red dwarf in absolute (bolometric) luminosity. As far as stability, this may be a bit dicey (to improve it, move the planet closer to the red dwarf a bit, and the distant star further away). HOWEVER, a fast calculation shows that the radius of the Hill Sphere around the red dwarf (where the gravitational pull of both stars is balanced) is 1.2 AU and a popular rule of thumb is that orbits are stable inside of 1/3 of the [Hill Sphere](https://en.wikipedia.org/wiki/Hill_sphere) radius. In addition, the paper by [Holman and Wiegert](http://arxiv.org/abs/astro-ph/9809315) on orbital stability of planets in binary star systems gives a formula for the radius of a stable orbit in binary star systems, and the formula for S-type systems gives a stable orbital radius of 0.57 AU or less\*, as long as the eccentricity of the binary orbit is low. \*-(For very low binary eccentricity, the formula for the maximal stable orbit around a star in a binary star system is approximately $d = (0.464 - 0.380\mu)\alpha$ where $\mu$ is the relative mass of the secondary star, or, in this case, $\mu = 0.75$, and $\alpha$ is the distance between the two stars) [Answer] If we can cheat a bit we can have two stars of the same mass but different colors. Their size will differ, though! To start with, lets take a star system consisting of a 2 solar mass star and 1 solar mass star, assorted planets. Now, we also need a system containing a 1 solar mass star and the planet of interest. Other planets are irrelevant. Apply lots of time to this system, wait for the 2 solar mass star to enter it's red giant phase. Now, they run into each other. The two 1 solar mass stars impact and merge into a single 2 solar mass star which will still be a main sequence star (this is one of the hypotheses for blue stragglers) Through some incredible luck the planet ends up in a suitable orbit around both stars. ]
[Question] [ In my world human(oid)s are not born anymore, they are grown in pods which mirror the conditions of a natural womb. Children are educated before birth and are "born" as fully mature adults with a standard education ready to join society. How long would this process take? I assume that artificial growth could be much quicker than a natural 18-20 year period. Could a human be grown in a year? A decade? [Answer] A year? No. Babies already require 9 months in the womb to get to where they get. You're limited because many processes in growth require chemical processes that simply take time. Humans simply aren't cars to be manufactured. A decade? Now its getting interesting. It is reasonable to assume that a human could grow faster in a "perfect" environment with genes to leverage that perfect environment. Its entierly possible we could reach "fully grown" in a decade. However, the womb would probably have to be adjusted. Many thing a human body needs require things that challenge their motion (so they can learn which muscles are doing what). The humans would be gloriously clumsy unless they got Physical Education as part of their standard education in the womb. A standard education in the womb you say? That education process might be very daunting indeed. You may be able to physically produce a human in a decade, but you may find it hard to properly educate them that fast. [Answer] Certainly not in a year, no. Growth is limited by multiple things, for example: * bone ossification - bones need to both grow laterally and also get ossified. There's a few values for bone growth in children [in this paper](http://www.boneandjoint.org.uk/content/jbjsbr/44-B/1/42.full.pdf) - basically, a few centimeters a year. * skin needs to grow. And the larger a person gets, the greater their surface gets. Think about how long wound healing can sometimes take. * neurons in the brain need to grow - your education alone will need several years, and will often have to wait for the growing brain to catch up You can estimate a lower limit from two scenarios: * there's people who never stopped producing human growth hormone, which is one of the factors in determining when children grow. [Robert Wadlow](https://en.wikipedia.org/wiki/Robert_Wadlow)'s body never stopped growing until he died at age 22 and roughly 270 centimeters. If he was born at around 50 centimeters, that's roughly 10 centimeters a year. * the "peak growth velocity" in teenagers, who grow the fastest, is also [around 9 centimeters a year](http://pediatrics.aappublications.org/content/102/Supplement_3/507) So basically, 10 centimeters a year would be a believable growth rate, meaning from 50 to 180 centimeters, you'd need about 13 years. Under optimal conditions, with great nutrition etc., a decade sounds believable. However, you might want to keep in mind that this is only lateral growth. [The human brain isn't considered fully mature until the mid-20s.](http://hrweb.mit.edu/worklife/youngadult/brain.html) [Answer] It **REALLY** depends on what level of technology we're talking about here. After all, given sufficiently advanced technology, we could "build" a person, atom by atom, to have all the same properties, education, mental and motor functions etc. as if they had developed the normal way over many years. --- Let's assume a level of technology that allows us to "develop" the brain in any way we like (including but not limited to: memories, knowledge, motor functions) as the body is growing, but which requires all the normal physical/chemical processes to take place. Albeit in an environment designed to optimise the speed/efficiency of that development. **My guess: 2-7 years** This is based on the fact that the environment you describe (No external interruptions, wholly optimised for and focused on development) sounds *very* similar to what we call "sleep". Now, sleep also involves lots of other functions relating to ongoing maintenance/learning/repair which we may be able to eliminate the need for in our growth environment. But then again, we have almost no idea of \*why\* humans need to sleep in the first place. So, I would suggest, for every day of "normal" growth, you will need a significant fraction of the time we spend sleeping, 2-8 hours or so, of "Test Tube Development Time". This yields 9%-33% of "Normal Development Time", so 2-7 years for a 20-year-old equivalent. [Answer] **18 weeks to 6 or 8 years, but it does not matter** 9 months to produce an infant is a long time compared to the initial growth rate of the embryo. At 4 weeks, the embryo is the size of a poppy seed (2 mm long), at 8 weeks, the size of a kidney bean (16 mm head to bottom). During that period, the human increased by at least a factor of 8. This is a growth rate of about 68% per week. At this rate, you are large newborn at 15 week and a full sized adult in under 18 weeks. So, we have a reasonable lower bound of about 18 weeks and an upper bound of about 18 years. But can we find a better upper bound? Yes we can, [Robert Wadlow](https://en.wikipedia.org/wiki/Robert_Wadlow) was the tallest modern man that can be reliably documented. At age 6, he 5'7" and was already taller than his father at age 8. So 6-8 years seems like a better upper bound since people can grow that fast with too much human growth hormone. Robert Wadlow had health problems and in fact died of medical complications of an autoimmune disease (possibly related to his HGH levels) at age 22. He was reportedly in good health until the final year of his life. His brain was certainly not mature at age 6 or 8, but lets assume that it could be close enough to be considered adult if he had a magical efficient training systems and nanotech to re-arrange brain structures as needed. So 18 weeks to 6 years. Hypothetically speaking, after all of the needed advances in technology, including nano-tech what could we do? The answer is simply unknown since we don't have the medical knowledge of the complications of accelerated growth in an artificial womb. Perhaps with nano-technology we could control physical growth, perform the necessary muscle and bone training, deal with the psychological and sociological training. Training the interactions between the brain and eyes, ears, hands, etc. Perhaps it is also possible to teach language, reading, writing, arithmetic, etc. in the womb. There is a huge gulf between our current state of knowledge and that needed to perform all development in the womb. And there is very little incentive to acquire it. Parents want to watch their children grow up, play, learn from their environment, etc. I can't image any parent I know desiring to replace this process with an artificial one. [Answer] Human growth is subject to many limiting factors, including the ability of the mother to supply the required nutrients to the foetus, and after birth, the ability of the child to acquire the full range of expected social skills. A young human is physically small in order to convey the impression of youth to other humans. Since learning to be an adult human takes around eighteen to twenty-five years, that is how long it takes for the human body to mature fully. Size and other physical traits conveys an impression of age to others. Now, if humans could grow to maturity and be born with all necessary knowledge to be fully functioning adults, as well as be free of the limitations of maternal nutrition, growing such a human in-vitro could occur in a relative short period of time. In larger mammalian - and dinosaur - species where achieving an adult body-size (of several hundred kilograms to many tons) as quickly as possible is of paramount importance, very high growth rates can be achieved, with newborns achieving maturity within a handful of years, certainly within 5 years or less. We could therefore expect that with genetic engineering - or some clever artificial stimulation - to remove the limits on pre-maturity growth-rate, a fully mature human could be produced within three years. I should point out that if humans were genetically engineered to grow that quickly, it would effectively sterilize the population and make them dependent on artificial reproduction. Should a modified human mother become pregnant, her body would not be able to supply the huge metabolic needs that such a foetus impose on her, and a significant or even fatal loss of body mass would likely occur. Should the foetus survive, it would be no better educated than any normal human newborn. On the other hand, if humans were grown rapidly and educated in-vitro through medical trickery rather than genetic engineering, a natural pregnancy would most likely be possible, with a normal-sized infant being born after the usual period of gestation. It is up to you if the mother would have been educated sufficiently to have the knowledge to handle a naturally-born child. ]