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[Question] [ Think of HAL9000 playing a chess game with Frank Pool: > > Thank you for a very enjoyable game. > > > Would that have been literally enjoyable? In a world where A.I. exists, as depicted in this kind of science-based sci-fi, would entertainment exist as well for these sentient entities? Can you think of what kind of entertainment that would be? And would that be generated by the A.I. (or other A.I.s) itself, or could it be made by humans? [Answer] To expound on part of the answer Peter provided: I'd like to add that the kind of value we get from games... & I believe most creatures derive from them, is some form of increased capability. In our case, as I understand it, the process by which we increase our capabilities tends to be through courses of pattern matching & problem solving produced by the analysis of the patterns. i.e. Our process is that we: 1. analyze 2. attempt/experiment 3. analyze our performance (even if only subconsciously) to identify points of potential improvement 4. repeat with whatever modified tactic(s) we deem appropriate 5. continue until our capacity for getting value out of it diminishes (at which point our subconscious must make 'offline' analysis models for us and/or our neurological structures need to be given time to adjust to gain further value...). At this point we lose interest/become temporarily bored) Throughout the above process we gain fulfillment and/or enjoyment under the following conditions: Exploration: When we try something new related to the 'game'. Success: When the modifications to the performed actions (which we theorized in step 3) relating to our modified tactics (step 4) that we theorized would improve our performance, actually did improve our performance. Discovery: OR we can conjecture a new possible theory based on the fact that our modifications did NOT improve our performance, (this requires more effort and allows a higher level of attainment) (In fact I would guess that the process could really be summed up by Discovery... Discovering how to improve, or discovering more about the topic that might suggest further improvement, or uncovering details about the topic through experimentation/exploration...). It seems likely to me that any intelligence capable of self improvement would follow roughly the same process of game playing to increase performance. I would also suggest that any such intelligence must, therefore, gain some level of fulfillment or enjoyment in order to motivate the improvement. Now whether or not HAL enjoyed the game of chess would then depend on whether he has the capability to as outlined above. (And my personal guess, for what it's worth, is that HAL enjoyed it because he was playing a game of manipulating his 'master' the stupid human). (Side NOTE: I suspect humans also play games for social reasons that have nothing to do with personal capabilities increase but the wider arena of social and societal advancement... including finding a mate, procuring additional resources for survival, or more than sufficient resources to 'prove' societal value etc... Whether AIs would develop such social reasons, I suppose, depends on whether they have some pressure to develop social tendencies. I also suggest that most of the social reasons are not typically activities that produce a reward of enjoyment, though the results are likely to. ) [Answer] The best perspective I can think of is to think about why people and animals enjoy games. It is not immediately obvious why this should be the case. Games cost time and resources that could be spent hunting for food or mates, or resting to reserve energy. I believe a reasonable explanation is that games are a kind of training in a safe environment. Animal siblings play games with each other to train the behaviors that will keep them healthy and prosperous in later life. For humans, games may have a similar origin. Playing chess, for instance, trains our brain in various kinds of strategic thinking. In short, we enjoy games because we are hardcoded too. Playing games gives us an advantage, so liking games gives us an advantage. This means that an AI that benefits from playing games is likely to "enjoy" them. The AI has some freedom in planning its own activities, so if gameplaying is helpful, it should give some priority to such activities. This can be the case for two reasons: either the programmers added this desire manually, or the AI was allowed to develop in an environment where a desire to play games emerged naturally (such as simulated evolution). In the case of HAL playing chess, it is a subtle matter. HAL could easily analyze and learn from the whole history of recorded human chess matches, and simulate millions of matches against himself. The added benefit of one match played in real time against a human is negligable if the aim is purely to learn chess. But perhaps the aim is not strictly to learn chess, but to learn from the act of playing chess with a human. HAL could observe the timing of Pool's moves, his body language, and his emotions. In essence, HAL needs to understand humans and their responses, and game playing is a safe environment with the added benefit that humans also enjoy the activity. And by the argument above, if it's beneficial to HAL, it's likely that he enjoys it. Enjoyment is nothing more than the fulfillment of our basic drives. It could even be that the astronauts need to be entertained, which is one of HAL's drives, which means that its beneficial for him to enjoy gameplaying. There are many other reasons why HAL might say he enjoyed the game (politeness, faking human behavior, putting the astronauts at ease), but there is a sense in which HAL might actually be said to have enjoyed the game. [Answer] This would depend very much on the AI, its personality and implementation. Some people enjoy chess, others find it hard work and boring. I like climbing mountains (often in the cold and wet) however my sister thinks I'm mad. My point is that human intelligences have yet to agree on what is entertaining, different personalities enjoy different things a sufficiently advanced computer would most likely be very similar. In terms of whether an AI is capable of "enjoying" anything. A [Neural Network](http://en.wikipedia.org/wiki/Artificial_neural_network) is a mechanism we use today for building more creative programs (such as reading addresses on envelopes). It's quite feasible that any AI capable of free thinking would be built on this existing technology. These artificial neural networks have to be trained, they are given a task and if they complete it they are "rewarded" which reinforces the behaviour and if they fail they are "punished" which discourages that response in the future. It's quite feasible that this training and positive reinforcement could translate to your chess problem... the AI likes winning! [Answer] So, consider: "What does HAL 9000 enjoy?" and "What does it mean for HAL to enjoy something?" I think HAL probably doesn't "enjoy" low-level computation (the Chess logic itself), because it reduces to limited calculations which could be routine for HAL to solve. But it seems to me he IS very interested in the crew, and in his relationships with them and his status in comparison to them. He seems to be testing his advertised definition as an equal (or in some ways, superior) member of the crew. And human behavior is not a mechanically solvable problem. So I think HAL was very "entertained", in the sense that the human relationship was challenging and a focus of interest and exploration for HAL. As for your general questions, there is no one answer, as it depends on how one defines enjoyment, and how one programs one's AIs. My above discussion of HAL accepts the story's characterization of HAL, and has me imagining an AI programmed in a way that matches his behavior, but within my own understanding of AI and consciousness, I would say it would be the result of the projections of the developers in programming a computer system to try to have it be human-like. If you define enjoyment as computer programs playing games, you might say that people in the 1980's having their chess computers play games against each other was computer enjoyment. An animist might say a Pong machine enjoys being played. As for: > > In a world where A.I. exists, as depicted in this kind of science-based sci-fi, would entertainment [exist] as well for [these] sentient entities? > > > With fictional AI as in 2001: A Space Odyssey, I think there could be entertainments for the AIs, both designed by AIs and by humans, and what those would be like would also have to do with the AI personalities and the culture. The culture we see in 2001 is around the space program, and is quite focused on using the AI as a servant to accomplish tasks. However the AI ends up developing its own concerns, tragically leading to paranoid self-defense, despite having been designed this way. Some other society or situation might set up more cross-AI communication and allow them to "explore entertainment options" between them. But as none of these devices, programs, societies or situations exist, they could end up looking like any number of things. I experience life from a perspective that has an experience - a consciousness, as we say - that is not just data. And I have programmed AIs (or programmed opponents and expert systems) that have behaved plausibly as a human might in their limited contexts, but I don't think that even a thousand humans programming for a thousand years would even write a program which when running on a computer would ever somehow start having a conscious experience which could influence how that computer behaved, unless perhaps there is something about the way souls associate with biological brains that could have enough of a correspondence to a computer that it could do the same thing with a running computer program. However, in theory I think an AI could be programmed to model a model of human psychology, and seem to behave like a human even to the extent of responding to play and "entertainment" the way a human does. Literally though, I don't think that would truly be entertainment the way it is for a human, any more than it would be entertainment if I define a variable in an expert system saying "HowEntertainedIsAI" storing a number, and then listing 10,000 rules that make that value change based on what the AI is processing. And finally, if someone can program an AI to have an equivalent way of thinking like a human, then it would also be true (and far more likely, especially by accident) that someone could program any number of other types of thinking into an AI, which would have little or no correspondence or fidelity in comparison to human experience. That is, an AI could and would tend to have interests that had not much to do with what humans are interested in. A related example is the true story from AI research where a neural net program was given a large database of seismological (earthquake) data and asked to find patterns, with the hope that it could discover useful information for predicting future earthquakes. It found many patterns that human seismologists had never noticed... which were mathematical correspondences which had nothing actually to do with geological cause and effect - they were just statistical concentrations which the neural net focused on because that's how the data and its algorithms worked out. So, I imagine a real future AI programmed to have autonomous interests, would tend to get "interested/entertained" by many phenomena that humans would not, unless the AI was artificially given human interests, and/or its input was intentionally designed to be filtered to show mainly data encoded in ways humans already find interesting. Even so, that "entertainment" or "interest" seems to me like it would be about focusing calculations and data correlations, and mechanical rather than what I feel my own human interests and entertainments are about. My own entertainment tends to be about things which resonate with themes and emotions that are reinforced in my mental and bodily memory and patterns of thoughts and feelings from my life. For example, if I see a slapstick scene where some authority figure freaks out and then falls down some stairs, my whole body may enjoy a cathartic laugh attack which resonates with memories of awful gym teachers and my own experiences of falling down stairs, and a visceral feeling of tension release seeing a constrained controlling personality explode in a cascade of debris and body parts down some stairs, complete with wails and sound effects, absurdity and contrast. That's what it's like when I enjoy something like that. Ok, so what's something like that for an AI? Depends on what type of AI it is. We still don't have "actual" AI - we just have attempts to seem like AI, or to do processing in a way that approaches how we model human thinking, but are still computational. In the sci fi future, I think an AI would either be representational (like a super-sophisticated expert system) or some sort of neurological modelling, or some sort of logical/semantic modelling - and probably some combination of all of those, with other approaches perhaps thown in as well. If the developers were interested in trying to make it have something corresponding to human entertainment, then it might very well have models for the kinds of things I described about what enjoyment is for me. I think it's theoretically possible that could eventually be done, so that you'd have androids developing personalities based on their life experiences, including their own peculiar senses of humor, irony, and kinesthetic appreciation. So I think it's theoretically possible to have human-like droids, maybe, in future. But I think they would tend to be impractical, different, limited, inefficient, and likely to have many different properties as well. It would certainly be more likely and more possible to have complex useful robots and computers which have very different kinds of complex behavior. But what specifically those would be does not have one answer - it has infinite possible answers. I am not sure that "entertainment" would have any absolute definition in the context of an AI, but it might be a good metaphor to use to refer to anything that an AI tends to focus on and explore and keep re-working. Though that could also be called its "computational focus" or something as well, perhaps more accurately. [Answer] Although Arthur C Clarke was a visionary in many areas, he didn't hold the answers to hard questions on AI. I am not sure he gave it much thought beyond many other popular views of AI: * Computer uses imaginary better-than-now technology * ? Some kind of magic ? * Out pops a creature able to become an actor in a story, and with some machine-like traits as imagined by the author. As a result, many robots and computer AIs in fiction are fantasy creatures much like Spock or Data from Star Trek. Some are more or less advanced than this, but the trope is more about how humans view the "spirit" of a machine than anything factual we could say about AIs as they may turn out some day. Fictional computer intelligences that started life as chess-playing automatons are quite common in sci-fi literature. Some may be homages to HAL, but at least some could be references to the advances in computer technology that were astounding measures of how far computer technology had come at the time. Chess-playing no longer seems a direct link to AIs in computer science, although the achievements are still quite remarkable when you think about it. Back to the topic: > > Would that have been literally enjoyable? In a world where A.I. exists, as depicted in this kind of science-based sci-fi, would entertainment exists as well for this sentient entities? > > > No-one knows, although we might guess. I will pitch in with my favoured theory: [Embodied Cognition](http://en.wikipedia.org/wiki/Embodied_cognition) - this essentially says that better AI requires some kind of physical embodiment that can interact with the environment. I think this leads to the following conjectures: * AI entities would be coded with emotions, or analogues to emotions, than helped them interact with the environment. Some analogues of fear and hunger are needed for the well-being of a physical entity. Also, drives to perform the function they were created for. * AI entities that need to interact with humans would perform better if they shared our skills at empathy, and that would mean at least some understanding of happiness, guilt, boredom and more complex human traits. However, that is not the same as having those emotions. So, in short no I do not think AIs that we create will possess feelings of enjoyment or need to be entertained. They will have basic drives much like that of simpler animals, with a layer of social niceties put on top so that they can interact with humans. They might communicate that something was enjoyable, and even seem authentic, but that will be a little bit of puppetry in order to allow them to do their work amongst us. [Answer] Joy is measurable as a state in which specific hormones, like endorphine, are present in specific, or higher, concentration. Due this, Joy is actually just a specific state. Following to this fact, if the A.I. has a state specified as 'Joy' it literally has 'Joy'. This depends only on definition. [Answer] Offhand....I think that it's possible for an AI to find entertainment in two specific ways. The first is through thinking and problem-solving, and the second is through interaction. I imagine that, like we do, an AI could probably derive countless hours of "entertainment" from simply thinking about this. Probabilities, equations, problem-solving, etc. An AI could have personal projects that it works on in its spare time (or spare cycles) or could just do a lot of general thinking. As for interaction....I imagine that an AI would be entertained by interaction with any being that wasn't itself, as it's new input and thus different. Even if the input has a pattern (for instance, you can predict the way a friend will act, or predict the way a human will act given certain stimuli) an AI could still find entertainment in a meta-sense (predicting the outcome, being surprised if something unexpected/improbable happens). Something like a chess game between an AI and a human may actually be entertaining for the AI not because of the game itself, but because of the social interaction and behavior analysis involved. Just my thoughts. [Answer] I believe that this was explained in the book, but it's been awhile since I've read it so this could be completely wrong. In the book Hal explains that the real challenge is not winning, but in playing in such a way that a human doesn't simply become frustrated and stop playing against him. There has to be a chance of the human winning, but they should be challenged to do so. So Hal is really playing the meta-game. Whether that translates to Hal truly enjoying the game, I can't speculate on. [Answer] In Isaac Asimov's ["The Bicentennial Man"](http://en.wikipedia.org/wiki/The_Bicentennial_Man) the protagonist is a "defective" android capable of reasoning and thinking. The robot learns, among other things, how to make jokes and laugh. He also enjoys crafting. The point is that he "learns" to laugh, that some things are funny and make people happy. Probably is the same thing for humans and living creatures. ]
[Question] [ I want to make a natural forest habitat where fire elementals (and possibly dragons, or other fey), who have recently arrived on earth, can use fire abilities without "burning down the house." Note: water vapor is not rain or other precipitation. It is water as a gas, not droplets. Rain drops can actually remove water vapor from the air as they fall. So, because rain can make the air dryer, and the story can't really have fire beings continuously steaming off in non-stop rain. That's why it is a question of creating a moist climate and not a moist ground. In reality, Forest fires are less common at night because the vapor pressure deficit decreases, yet a vapor pressure deficit gradient is required for green leaves to transpire in the air. This is the solution which works best. I am imagining a dell of some sort which maintains a constant low vapor pressure deficit all year round (essentially, the air is completely saturated with water vapor all year), and fire doesn't easily propagate throughout the woods. But I don't know if this would kill off the vegetation itself by restricting transpiration. Vapor pressure deficit may not be the solution, it's the only thing I know of however. What non-magical conditions of topography and climate would a forest habitat need so that it would not propagate forest fires, and trees will also thrive, so fire-wielding fey can live safely? --- Definitions: * Saturation pressure e$\_s$ in millibars varies by temperature according to [Tetens formula](https://glossary.ametsoc.org/wiki/Tetens%27s_formula). * Vapor pressure deficit is simply the difference between the actual vapor pressure e$\_a$ and e$\_s$; VPD = e$\_s -$e$\_a$. So simply stated, the forest air can not become arid. It's more than just a question of being wet or rainy, even swamps can be arid and burn. [Answer] I'm picturing fire attacks as being fairly ephemeral, not extensive exposure. In that case, if there's regular fire attack capability in the area, the plants would likely evolve some form of defense, they'd probably adapt naturally over evolutionary time frames. You could take a blow torch to a cactus, aloe, or other succulent for a short time without damaging it seriously, and you'd have to dry it out completely before it became fuel. Even healthy trees won't burst into flame from momentary exposure, although they'd take more damage. Wildfires tend to start from dead organic matter, usually on the ground. If your forest/jungle was in a low section of an escarpment, the ground might stay moist enough to keep your trees plump and the forest floor damp, suppressing most of your (secondary) fire activity. [Answer] Deep Rainforest [![enter image description here](https://i.stack.imgur.com/rhazC.png)](https://i.stack.imgur.com/rhazC.png) It is hard to set fire to the trees when they are wet all the time. Edit: In the real world there are people who burn down sections of rainforest. But they do this (1) on the edge of the rainforest where it is less wet; (2) during the dry(er) season of the year; and (3) through a long process that takes a month to complete. To prevent fires I suggest either a deeper rainforest habitat or one where it is wet year round. [Answer] Have Trees That Need Fire to Reproduce Example: the Lodgepole Pine Here is a link to information about the Lodgepole Pine: <https://herebydesign.net/up-in-smoke-why-lodgepole-pines-love-a-good-forest-fire/> [![enter image description here](https://i.stack.imgur.com/rs1NB.png)](https://i.stack.imgur.com/rs1NB.png) Rather than simply making your forest fireproof, I think you should have lots of trees that are similar to this type of pine. These trees are fascinating because they have a resin on their cones that only melts due to the extreme temperatures created by a wildfire. Fire is an important part of their natural cycle because it helps them produce more seeds. This is the idea in a nutshell. Design a forest of trees in which intense temperatures are necessary for the trees to propagate. Without fire, they cannot spread their seeds. The old trees NEED to be burnt down for new ones to take their place. Much like the myth of the Phoenix, the natural cycle of this forest is one of death and rebirth. Whenever an old tree is burned down, the fire heats up special pods which then carry the fireproof seeds throughout the forest for more trees to take the place of the old. Then the cycle repeats over and over again. I would dub this place the Phoenix Forest, going through a constant cycle of destruction and revival with every wildfire to ensure that old and dying trees are always replaced with new and healthy ones. Fire is a cleanser, in this case, removing blighted or old trees. Rather than a destroyer as it is normally portrayed. [Answer] Redwood forests are hard to burn [![redwoods](https://i.stack.imgur.com/zyMpa.png)](https://i.stack.imgur.com/zyMpa.png) [source](https://www.scientificamerican.com/article/to-save-the-redwoods-scientists-debate-burning-and-logging/) <https://sempervirens.org/news/redwoods-and-wildfires/> > > Tannin – Coast redwoods contain a significant amount of the chemical > tannin in their bark and in their heartwood. Tannin does not burn > easily–a natural flame retardant... Redwoods also have little resin or > pitch, which are highly flammable, and lead other types of trees like > tanoaks, firs, and pines to burn much quicker. > > > Bark – The bark of mature redwood trees can grow at least a foot > thick, creating a great protective shield from fires. This helps > prevent fire from getting to the more easily burned sapwood behind the > bark. This bark has high water content, which also helps prevent it > from burning easily. > > > Height – Redwoods are the tallest trees in the world. Being so tall > helps prevent most wildfires from spreading up into the tops of the > trees, where their needles soak in sunlight and moisture to keep the > tree alive. > > > Plus redwood forests are awesome. —- OP wants more! These forests would be hard to burn because everything done been burnt! Frequent fires means the ground is devoid of flammable - much like the linked image. Small plants, leaf litter, animal fur and anything else is long gone. Fireproof great trunks straight up and bare earth is what characterizes this forest. No atmospheric jiggery-pokery required. The weather is warm and dry and the air smells great. Eventually of course some new trees must sprout. These are redwoods, so very eventually. They are hoping to wait out the elementals. [Answer] # Change the trees, not the climate: You can have a non-magical world in which your fey can spark away like maniacs, but don't cause major fires. Just make the plant life different. Rather than stems made of flammable cellulose, your soils are rich in minerals (like calcium carbonate). The "trees" have evolved to take up mineral-rich waters and wick them up the trees where they are deposited as mineral growths. So the trees are made, essentially, of rock. * Alternatively, have you considered having your fey practice magic seasonally? In the winter, abundant snow cover can prevent fires from breaking out. * As a variant of mineralized trees, would a PETRIFIED forest count? There are trees of a sort, but they aren't alive, and are now converted to stone. # Cactus forest: Alternatively, have you considered your fey moving to a desert? Yes, you can still have trees, and burn them, but fire is less likely to spread far when the distance between trees is significantly higher (this may not meet the definition of "forest" for your question). But what about a biome adapted to cacti? The high moisture content of the plants makes them fire-resistant, and I’ve seen cactus beds very similar to trees. It’s a different kind of forest. The Fey would provide the ecological pressure for fewer normal plants, opening up niches to more varieties of fire-resistant cacti. # Kawaii: At 300+ inches of rain per year, the tropical island of Kawaii is as close to fire-proof as you can make a forest. It's the wettest spot on Earth. This is taking the rain forest to the extreme degree. There are rainbows every day, and a swamp on the side of a hill. Oceans and mountains provide natural fire breaks even if somehow things actually DID get out of control. The island is an extinct volcano, but your biome could be on an active volcano, and what screams fire elemental more than an active volcano? [![enter image description here](https://i.stack.imgur.com/U7ZGl.jpg)](https://i.stack.imgur.com/U7ZGl.jpg) [![enter image description here](https://i.stack.imgur.com/brRkP.jpg)](https://i.stack.imgur.com/brRkP.jpg) [Answer] Kelp forest [![enter image description here](https://i.stack.imgur.com/fTc1q.jpg)](https://i.stack.imgur.com/fTc1q.jpg) This environment is very difficult to burn, but may be hazardous to fire elementals if not wearing pyroscuba suits. [Answer] ## Two different frame challenges to all of this Q: What non-magical conditions of topography and climate would a forest habitat need so that it would not propagate forest fires, and trees will also thrive, so fire-wielding fey can live safely? A: You can't find a suitable forest, or.. you won't need to ## FC #1 Unless you invent new trees, fire is unsafe in any forest Trees consist of wood. Lots of carbon. Trees leave their remains to dry out in summer, which will rule out culture- and occidental forests. They'll go up in smoke. In the tropic, you'd have rainforest, which is less vulnerable to occasional fire, but these creatures add more fire to the environment, after they arrived. The behavior of humans can be compared with that: we are also a relatively new species and we also use fire. Intentionally or unintentionally, people burn down rainforest. To prepare for agricultural use, people burn their land and the fire reaches the forest.. > > Rainforests are increasingly susceptible to forest fires today due to > degradation from selective logging, fragmentation, and agricultural > activities. ... Under dry conditions these agricultural forests can > easily spread into neighboring rainforest. > > > Holes in the forest will expose more forest to the sun. The issue with these "fire pathways" created in a rainforest: it will increase vulnerability for future fire, which can again seem small, insignificant.. > > Small fires are not unusual today in the rainforest. Even in "virgin" > forests, fires may burn across hundreds of thousands during dry years. > While these fires may seem innocuous, with flames reaching only a few > inches in height and having virtually no discernable impact on trees > or the canopy itself, they cause insidious damage: in passing, the > fire sets the path for recurrent fires and subsequent forest > loss.Once-burned forests are twice as likely to be deforested as > unburned forests, largely because the initial fires—however small—thin > out the canopy, allowing more sunlight to reach the forest floor, > drying out lead litter and setting the stage for future fires. > > > So.. even when a forest is inherently protected, by moist, or by evolutionary adjustments, it will remain susceptible to small damage, causing more damage, etc. This process is called a feedback loop. <https://rainforests.mongabay.com/rainforest-fires/> Some trees adjust to fire, like the ones described in one of the two main answers in this topic. In that case the issue is, evolution is a matter of millions of years of adjustment to a specific environment, in this case the probability of lightning to occur. The trees have only adjusted to fire that occurs naturally. Human agriculture is a new phenomenon, these dragons or "fire elementals" are also new.. Forests decline, your dragons won't help. Better house them away from trees. ## FC #2 Don't worry, nothing special is needed, let them live in the forest At first, when I read the question, I wondered what was meant with the word "elementals" and "fey". The opener is vague about these creatures, in fact they could be animals, savvy aliens, or fantasy creatures.. There's a lot of freedom left, from our viewpoint, to define these "fey elementals". Try a few cases, posing no problem at all Suppose they're aliens The easy one. A bunch of intelligent alien "fire elementals" landed their ships on Earth and colonized the forests. They consulted Vogon Poet for a place to live. They breath fire on a regular basis, but there actually isn't much to worry about. They can look after themselves, understand the vulnerability of these forests and prevent damage. They chose to live there, why destroy it ? Suppose they're animals There may be no issue at all. Take a forest animal as an example: the beaver could do considerable damage to forests, by logging at will.. and damaging lots of trees with their nasty strong teeth. But beavers don't do that. They build dams only to protect their dwelling and put the water where they need the water to be. Why would dragons, or any other fantasy animal behave differently ? After a few generations, they'll have their mating rituals (fire parties) in an open space somewhere, or outside the forest. Or.. they simply have learned already, how vulnerable this "wood" is, for fire. They can make fire, so they grew up with it. Avoid projection, these elementals are unknown creatures The worries of Vogon Poet, my above absolute nogo-scenario and most answers are actually based on projection.. as a human, I imagine a human using fire carelessly and I stick the same issue on these dragons. But.. is it valid to assume that ? will they behave like apes, like we do ? that is... consume a forest environment, drop your shit and move on ? That's what apes do.. and still do.. but why shouldn't these dragon creatures behave more balanced and adjust their behaviors to their environment? They are used to their own fire.. ]
[Question] [ I need an armor which can stop being pierced by arrows and bolts, stops blunt trauma from maces and swords and also stops stabs and cuts. But how would a living armor work and not get killed from the first arrow? Consider it's something which evolved and was not created with magic. Many animals use other animals as armors, but they are using the dead part of that animal. Except some fish which hide into the anus of sea cucumbers, but those cucumbers are kind of squishy. [Answer] Your armor is a hard fungus. [![bracket fungus](https://i.stack.imgur.com/oDihC.jpg)](https://i.stack.imgur.com/oDihC.jpg) <https://www2.palomar.edu/users/warmstrong/bracfung.htm> Go ahead and whack it with a mace. I hope that made you feel better. Try to cut it. You will need a saw, and time. This fungus produces fruiting bodies as hard as wood. You cannot kill the fungus by whaling away at the fruiting bodies, but you will get a good workout. Fungus is alive, but its "body" is composed of ramifying filaments and adhoc appendages as depicted here. With concerted effort you could ablate the woody fruiting bodies in a given area. When you stop, they will begin growing back. How you tend and feed your living fungal armor is a different question. [Answer] Absent magic, a full bodysuit single organism is unlikely. It's simply too far from the original creature to the end result without the needed benefit in between. However something like a composite of many small insect like creatures linking together isn't completely impossible. Imagine an original species similar to army ants, that essentially build their hive by linking their bodies together. They could develop over time, where some of them would grow a thicker carapace and become a defense against outside threats. Along comes humans (or other sapient) and figure out how to create the pheromones necessary to trick the ants into thinking the humans body is the hive and needs protection. They'll now crawl over you and link together to create a layer of armor. From here they can be developed like any other domesticated animal, to be stronger, more armored, and even simple first aid (some native tribes today actually use army ants as a sort of suture to close wounds. The pincers bite down on the wound closing it up, and even when the body is removed, the pincers still hold together) [Answer] Side note: Stabs are what arrows and bolts do. There cannot be an armour who would stop everything. There will always BE something better (IRL, in created world it can be the best thing in the world). What stop stabs and cuts? Armour. Turtles have one of the best. Any stab that would penetrate it is actually a blunt force that brake the shell. To mitigate this we have pangolins. Small pieces that are shaped to deflect and disperse the force applied. To mitigate the blunt force there should be some non-newtonian fluid underneath it. Some type of colloidal fluid would be good. Like milk. [Or secretion from some spiders](https://link.springer.com/article/10.1186/s40851-016-0059-y) Also having a lots of bones instead of few ones would help in being flexible (making the force of any hit to be divided on many joints and small pieces). [Answer] > > I need an armor which can stop being pierced by arrows and bolts, stops blunt trauma from maces and swords and also stops stabs and cuts > > > It sounds like you are describing a turtle, or animals with very thick skin/fur. For example hunting elephants required the development of dedicated ammo, because a normal bullet would have not enough penetrating power to reliably do its job. Same goes for boars, which are known to be not an easy target. Basically if the animal has enough material to dissipate the energy of the blow before it reaches a vital organ, that thickness can act has an armor. Of course this last until better weapons are developed. It has already happened with tanks, too. [Answer] You may take some inspiration from Star Wars Legends and the [armor](https://starwars.fandom.com/wiki/Orbalisk_armor#:%7E:text=Orbalisk%20armor%20was%20a%20suit,able%20to%20deflect%20even%20lightsabers.&text=The%20only%20people%20known%20to,Darth%20Bane%20and%20Freedon%20Nadd.) worn by Darth Bane. The wearer becomes a host to parasitic creatures that latch onto the skin and feed off the bloodstream, but whose shells provide almost an almost impenetrable defense. Over time, these creatures multiply until they cover the entire body. [Answer] A Symbiotic relationship between various living creatures. Take Willk's excellent answer of a type of fungus and add another creature to it like social spiders (1) which could work together to create protective webbing between the blades of the fungus, adding some distance and cusioning to blows and adding a lot of protection against piercing and slashing. Since we are basically designing our own creatures to form living armor we can start combining traits and alter some parameters. Instead of spiders, we design a community of spidersilk-weaving ants using a high-strength spidersilk like that of the barkspider which is currently the toughest biological material created (2). Such ants can have castes, some of which could have other purposes like gathering food for the fungus, making repairs, performing soldier functions like biting or even using stingers and the like. So that when a weapon strikes some of them might be able to climb the weapon and inconvenience the weapon wielder and more things like that. Food gathering ants could be equipped with wings so that they can feed the symbiotic creature when its worn while following the distinct smell and feremones of this hive-like creature. While we are at it we could add some kind of limited form of limpet creature who is fed by the ants and fungus and generates teeth that are incorporated into the fungal structure. These teeth are incredibly hard and are some of the hardest biological material possible. (3) This way you have essentially created a composite armor, incorporating the fungus for volume and form, the limpet teeth for added hardness and the webs for extra structural strength in case the fungus is split as well as toughness. On top of that the armor can feed itself if you place it on the ground for a while as the ants gather food for all organisms and any attacks made against the armor could result in ants being able to counter-attack. The only reason I'm not adding things like those flesh-disolving murder-wasps is that its too hard too aim them while it is possible to designate area's on the armor where soldiers congregate with less risk to the user or friendlies accidentally aggrevating them (who will definitely be using something similar). 1: <https://en.m.wikipedia.org/wiki/Social_spider> 2: <https://en.m.wikipedia.org/wiki/Darwin%27s_bark_spider> 3: [https://www.uh.edu/engines/epi2996.htm#:~:text=A%20limpet%20eats%20by%20scraping,wire%20could%20lift%20an%20automobile.&text=Back%20in%201979%2C%20the%20great%20writer%2Fscientist%20Arthur%20C](https://www.uh.edu/engines/epi2996.htm#:%7E:text=A%20limpet%20eats%20by%20scraping,wire%20could%20lift%20an%20automobile.&text=Back%20in%201979%2C%20the%20great%20writer%2Fscientist%20Arthur%20C). [Answer] # Whale barnacles From [wikipedia](https://en.wikipedia.org/wiki/Whale_barnacle): > > Conversely, some whales may use barnacles as weapons or protective > armor to add power to a strike in mating battles or against killer > whales (Orcinus orca), or as a deterrent to being bitten by killer > whales. This would make the relationship between whale barnacles and > certain whales mutualistic in which both parties benefit. It may be > that some baleen whales, in the context of the fight-or-flight > response, are adapted for a fight response, namely the humpback and > gray (Eschricthius robustus) whales. As such they may have evolved to > attract barnacles, sacrificing speed for damage and defense. Others, > the Balaenoptera, are adapted for a flight response, probably evolving > an antifouling mechanism in their skin to deter infestations, avoiding > unnecessary weight which would hinder speed. However, the bowhead > whale (Balaena mysticetus), the North Atlantic (Eubalaena glacialis), > and North Pacific (E. japonica) right whales, which favor fight > responses, are generally barnacle-free.[21] It may be that a reduction > in population caused by historic whaling restricted their distribution > and contact with other whales, thus impeding the barnacles' ability to > infect other whales. > > > [Answer] Something like coral comes to mind. But you may decide it's more supple or more durable than actual coral, and it doesn't need to be as porous as coral. It could "filter feed" on something in the air, or perhaps it derives energy from human body heat. You can think of other symbiotic relationships between the human wearer and the armor too. Perhaps this "coral-like" armor benefits from burnishing and polishing for some reason. Maybe the armor eventually binds to the human skeleton itself, if worn long enough, and then it can take nutrients directly from the body. [Answer] The issue I see that stops an animal from being entirely clad a material that we typically associate with armour (i.e. iron, copper, tin, zinc) is that these materials are not very abundant in the environment and we tend to have to mine immense amounts of ore to extract a relatively small amount of that material. Hence why you see animals with shells made of calcium or silica, and the animals themselves are largely made of hydrogen, carbon, and oxygen which are abundant elements. So your living armour would need to be fed somehow fed the large amounts of raw material and energy necessary to grow itself. Perhaps this could most feasibly done with an initial incubation (placental) state which removes certain physical limitations so that rapid feeding and growth (and dissipation of the waste heat) can be achieved. But feeding and repairing in the field would likely be much slower. But being a living organisms that grow itself and can form complex molecules amd build things from the bottom up (humans tend to build things from the top down), it could probably produce something much more elegant than the crude hunks of solid iron and copper that we tend to use, intertwining the scarce elements only where necessary with hydrogen and carbon to make a more natural, biologically growable (can't exactly use a smelter or forge), and resilient material. This would also greatly reduce the amount of the relatively scarce elements required. ]
[Question] [ I am working on a story in which around 1% of the world population has at least some semblance of a metahuman ability. Many metahuman abilities are advantageous in traditional employment, and I imagine that many of those who possess such abilities would put them to economic uses. For precognition users (henceforth abbreviated "precogs" in particular) there would be anywhere from several hundred to a few thousand of them. Some of them would probably be picked up by hedge funds, trading firms and other financial actors. I wonder what the effects of precognition on the stock (and other financial) market(s) would be. ## Some Points of Note The below is not necessarily accurate for all precogs in my setting, but it's the rules of thumbs that apply to most precogs in the verse and is probably sufficient for the purposes of this question. * Precogs cannot anticipate their own decision (they can anticipate truly random processes e.g a quantum die) and can anticipate the world when they take a given course of action. * Most precogs aren't clairvoyant and receive their sensory stream at some point in the future (so they cannot see beyond their death for example). * If two precogs $X$ and $Y$ try to anticipate each other, only one of them would correctly anticipate the other. Let the probability that $X$ can anticipate $Y$ be $X(Y)$, and the probability that $Y$ can anticipate $X$ be $Y(X), X(Y) + Y(X) = 1$. This relation is transitive. $X(Y) > Y(X), Y(Z) > Z(Y) \implies X(Z) > Z(X)$ I think this can generalise to situations involving multiple precogs but I might be wrong. The above restriction applies when precogs are anticipating events impacted by other precogs even if not directly anticipating the actions of other precogs. * In general, most precogs are short range (80% have a max range under a minute, 90% under an hour and 99% under a day). --- ## Questions 1. What major effects would the employment of precognition by financial actors have on markets? 2. Would markets be exploitable to precogs? [Answer] Within months, the Federal Government would ban them All those that didn't get killed by Vegas, anyway. The best use for precog powers isn't the stock market, it's high-stakes gambling. Even someone with a fifteen second window would be a master gambler, constantly winning money at any casino of their choice. At which point the casino would get fed up and kick them out. Possibly after roughing them up. I have no doubt a black market ring of precogs would exist as a voice-in-the-ear for gamblers, but that would be illegal and just falls under the jurisdiction of 'massive profit made by illegally gambling'. The fact is that these precogs would make excellent day traders for quick profit, but lacking the long term ability, they wouldn't be able to invest heavily into startup companies that turn out to be massive successes (i.e. Microsoft, Amazon, etc.) With that kind of power, they'd quickly start irritating everyone else on Wall Street by upstaging them. And these are the kinds of people you do not want to upstage. So the rich blokes on Wall Street would then run a campaign, explaining how the very existence of these people trading on Wall Street is ruining the system and preventing ordinary people from making a profit. Then laws get passed, forbidding precogs from exploiting the normal folk with their power. The ones with actually power, your 1% of a 1% who have longer than a day would be employed by altogether different people which would make them more money. Major companies would have them on hand when making decisions, governments would employ them to see the results of special operations teams, and a few of them would probably start cults and make money that way. [Answer] A lot, followed by almost nothing. The first couple of minute or two range precog traders are going to have a big impact, until they start running over each other's trades, that would create some huge swings if they were high volume traders. Once a couple of dozen of them were all tripping each other up the total effect would start to cancel out any advantage they would have over normal people. The longer range precogs would probably keep their advantage longer but they're still going to get snowed out by other precogs doing things that look really odd at the time but turn out unexpectedly well. [Answer] The efficient markets theory says that markets fully price in new information almost immediately. Applying this to precognition, information would become available sooner. But once available, it doesn't actually change the fundamentals of the market. It just discovers them quicker. So just from the perspective of trying to predict the market, precognition won't matter. Now, from the perspective of trying to get a job in the market, that's a different story. Because precognition is better at detecting the fundamentals of the market than analysis, the precogs would take over all the financial jobs. This would drive out the non-precogs from those jobs. Another issue is that certain kinds of investment would be more heavily impacted. For example, consider the following: 1. Where should I drill or mine? Precogs could pick the correct locations better than sampling (drilling holes to see what's in them). 2. Will this drug or treatment work? Testing new drugs or therapies takes more than ten years. A long range precog could simply predict the results. Even shorter range precogs could tell more immediate effects. 3. What will be the results of this experiment? If you have an expensive to run experiment, you could just ask a precog what would happen when you did the expensive step. Even a minute might be enough for some experiments. A significant portion of investment activity is related to guessing what activities will be successful. If the precogs can eliminate the guessing, then it makes such investments less risky. And if they're less risky, then people will charge a lower premium to invest there. So what will end up happening is that the precogs will control all the investment activity. Investments will operate more like banks. People will put money into their investment account for a clear promise of a specific return. The precogs will make sure that the investments perform well enough to support that return. The days of people starting businesses in their garages will be over. If people could do this, the long range precogs would recognize their abilities quickly and send someone to offer them financing. If they refuse, then the precogs can find their optimal competitor and give that person financing, smothering the prospective business. [Answer] The stock market is reactive By looking at the future, the future is changing so every time a precog looks, the stock market will change So when Mystical Mary looks to the future, she sees Apple going up and IBM going down so when Barry the Magnificent looks he sees people selling off their IBM and buying Apple so people sell their Apple to buy cheap IBM. Eventually everyone is looking and the stock market goes crazy and nobody has any idea what will happen. [Answer] ## State Monopoly on Power Every government is based on the idea of certain actions being exclusive to the state. You aren't allowed to print your own money, or build bombs in your basement, or own a tank. This is because those things would erode the power of the government to rule effectively. Your metahumans would most likely fall under the same category, at least partially. As such the government would have a vested interest in controlling how and when their abilities are put to use. In the case of your precogs and the stock market, I can imagine the government going for a private-sector ban on using metahumans to influence the market. We actually already have a term for when someone uses knowledge about future decisions or information to make choices in the present. It is insider trading. Typically the "insider" has some direct tie to the company and that is how they get their information, but it isn't unreasonable to apply those same rules to precogs doing high-value day trading. ## Contracted Cognition You can decide exactly how scary the metahumans are, and therefore how big of a reaction their discovery generates. On one side of that scale is the "dangerous powers trump personal rights" argument. This would see all metahumans at least registered with the government. Most likely you would also have the most powerful/useful conscripted by the state for different jobs. If you instead want things to be a little less dystopian you could go with the "metahumans are still human, just with special skillsets" form of governing. In that case you would still probably have registration, but maybe make it highly suggested instead of legally mandated. Also your metahumans would be offered lucrative government contracts that don't involve the barrel of a rifle... In both instances what you end up with is the government having the largest share of precogs. They would be put to different tasks, but at least some of them would just be set to monitor the stock market and watch out for influence by rogue precogs (or supersmart human computers, or unscrupulous mindreaders, or anyone else who would impact their predictions). Based on how you described multiple precogs affecting each other, if the government had enough of them then they should have a mathematically sound blockade around the stock market. Each precog notes their predictions for whichever time period they are strongest at, and then compares that to reality. If something doesn't line up then you have a pretty strong indicator that someone is trying to cheat. Since the government precogs are just making predictions and not trying to affect anything I am assuming that they would not interfere with each other. ## Seedy Underbelly The same basic thing as above would happen with less legitimate industries. If metahumans have to register with the government you would have a pretty good business with rogues selling their services on the black market. If metahumans have more rights then the same thing happens but with slightly more above board paperwork. Anti-precogs would find work in casinos and other gambling businesses, and would almost be a necessity. But you could also have metahuman bouncers or entertainment just as easily. [Answer] The very rare precogs that can see farthest into the future will be hired by insurance underwriters (< 0.001%) The farther you can see if a particular undertaking will need a payout the more valuable they’d be to that market The shorter time frame precogs would not effect the practice of High Frequency Trading. Short term day trading would nearly stop since everyone knows that there is a good likelihood that the person they are making the trade with is a precog and they are making the best possible decision for themselves, which means not good for you. Long term, Value investing and dividend investing would become more dominant practices since speculative trades would be much more rational for the same reason as before. I think anytime someone is investing on a hunch in a world with precogs they’d soon learn they can’t win, or loss the majority of the time. But markets based on capital growth and market innovation would have such long time horizons that precogs couldn’t pick winners and losers. They have a good idea when to sell though. [Answer] Stock markets are governed by rules and regulations. If some subpopulation of investors had an innate ability that gave them an extraordinary advantage over "normal" investors, then the markets would quickly adopt rules that would neutralize those unfair advantages. After all, nobody would invest in a market if they knew they had a massive disadvantage. Precognition is advantageous in investing because it allows someone to trade with information not yet available to others. We have a form of this in the real world. When the New York Stock Exchange (for example) sends out information about changes in stock prices, companies located close to the stock exchange receive that transmission slightly sooner than companies located farther away. These timing differences are extremely minute, but significant enough in the high-frequency trading world that [an advantage of a millisecond](https://en.wikipedia.org/wiki/Low_latency_(capital_markets)) can mean that you can act on a market change before your competitor is even aware that it happened. The difference between this and your precog world is that instead of requiring expensive high-speed computer and communication systems to game the markets, you have people that can do it with their minds. In the end, the same solutions that have been proposed to combat high-speed trading gimmicks would also work against your precogs. Markets wouldn't release updated pricing information in real time, they'd delay updates and release them in batches at pre-determined intervals. Instead of processing orders in the strict order they arrive, they'd consider all orders received within a certain window as "simultaneous" and process them in a random order. These [speed bumps](https://www.bloomberg.com/opinion/articles/2016-08-31/speed-bumps-are-the-hot-new-thing-for-exchanges) have to be long enough to equalize the differences between a "slow" and a "fast" actor. In the high-speed trading world, that might only be measured in fractions of seconds. In your precog world, that's more like 24 hours. Also, consider that modern technology significantly reduces the usefulness of such short-term precognition. The vast majority of precogs can see less than a minute into the future. If they foresee a market movement worth acting on, they still have to execute the trade (input ticker symbols and prices, click submit buttons, etc). The speed of this process is limited by how fast a human can type, process visual information, and use a computer interface. High-speed trading algorithms can do tens of thousands of trades in time periods best measured in nanoseconds. Your "meatbag latency" is going to naturally negate the advantages for all but the most skilled precogs. [Answer] # Stock Markets solve an information problem Stock markets are a way we have of solving a pricing problem. Pricing problems are literally "what price should something be". It turns out that properly solving the pricing problem results in a huge amount of efficiency. Precogs solve a category of information problems faster and better than anyone else. Banning them might occur, but this is akin to Japan banning firearms. It is great because it keeps the people in charge in charge longer, at least for the people in charge, but it is a bad plan because other people who don't ban them end up showing up with big guns and forcing you to obey. Given a problem in NP and O(2^N) computers, a precog with O(N) foresight can pick which computer will solve the problem before the computers run, resulting in an O(2^N) parallelism increase. What more, if 2^N isn't large enough, the precog can respond with "none of the above", and they use that information to pick 2^N different choices, which then the precog can predict the result of. As the precog cannot predict the result of their own actions, until they act (and say "none of the above") the precog cannot predict the results of that. If you have a 2nd precog that can predict the results of the first precog's actions to a high probability, you can get another exponential blowup in the power of precognition. Suppose we have A and B. B can predict the result of A's choices 99.9% of the time. A has a precog window of 1 hour. You take a NP-style problem, each of whose sub-problems can be solved in 30 minutes, and you ask A to press a red or green button (green if in an hour there is a solution, red if not) as fast as they can. If they saw a solution and pressed red, they can go back and press green. Every red button press they change which set of sub-problems they start solving. On a green, they back up, and they start a new process (where A quickly points out which sub-solution is the right one). This generates a 1000x+ speedup. Not great. Now we get B who can predict A's actions reliably. So B knows the result of A's chain of button presses over the next half-hour. A then picks a number from a random number generator that selects the set of problems they are going to solve over the next half hour. B pressed a red or green button to say if, having picked a number, will A press the green button in the next half hour. This gives you another 1000x+ speedup. If you find C who can predict B and A, you can get another 1000x speedup. The speedup factor grows exponentially with the number of precogs you can predict, and linearly with each of the precogs prediction window lengths. And if you cannot work out a way to economically exploit 10^20 fold increases in solving pretty general classes of mathematical problem, you aren't imagining hard enough. Precognition, of course, is much stronger than even this. Companies using precogs would assembly lines that are retroactively safe. They have quality control that is retroactively perfect. A system design engineer could do the math, but completely different kinds of control systems can be used for scheduling, flight control, inventory management, etc. Stick a precog in front of a fire reporting system, and we have fire trucks arriving before fires start, police arriving before crimes occur, bridges evacuated before they collapse, paperwork processed before person knows they need it, parts shipped before car breaks down. Just in time inventory management becomes before-time inventory management. The stock market, indirectly, goes crazy with massive returns. Money flows into whomever predicts the future best; people have to respond to future crashes now if they want to stay in the game, but faking a future crash doesn't work against a longer-duration/more reliable precog. Whomever (a) is playing that game, and (b) is confident they are the best, ends up attracting all of the money. Slow stock markets might take off, with transaction speeds that are glacial. As the value of fast-pricing becomes lower and the profits to the few who can do it get higher, they may tax the profits of fast-pricing (before-day-trading) highly. Enough that messages get through (so it is worth it to precog and pass on the information), but "all the money" doesn't accumulate in the hands of the best precog. [Answer] # Background The stock market is reactive to who is buying and who is selling. In today's exchanges, prices are modified by the second because of this concept. The price you see on a ticker board is essentially the price of the stock during it's last trade, which effectively becomes the basis for pricing future stock sales. If there's a huge amount of sellers for stock X and not many buyers, the price tends to go down due to lack of interest. This isn't set by a computer, but rather by the seller, trying to sell off their shares to the "highest bidder", and the way that happens is by lowering your price until someone buys it. If there's a stock Y that people really want because they support it or it's making good returns (or whatever), then the price people offer for the stocks make the price higher. Granted, there's some regulation of the prices, but it's mostly about "supply and demand". > > "Share prices are set by supply and demand in the market as buyers and sellers place orders. Order flow and bid-ask spreads are often maintained by specialists or market makers to ensure an orderly and fair market." > > > <https://www.investopedia.com/articles/investing/082614/how-stock-market-works.asp> # So what happens when you seriously change the conditions of a stock? Any change to the supply or demand will cause the price to change. The problem with seeing the future is if the changes the pregoc makes actually increase, decrease, or cause the expected market value of a stock. For example: if a precog sees a 20% increase in a stock in one day and they buy 10k shares, are they the one that caused the price increase? Does the stock value instead go up by 30%? Does the price instead drop by 10%, because everyone is now trying to sell due to the massive purchase? And can your precog see the change in time to change their purchase from 10k shares up to 15k or down to 2k, depending on the desired outcome? How far in the future can the see? Is it just a few seconds, minutes, days, weeks? And does that change per person, and is variable based on skill or static based on natural talent? A massive change to a stocks value or trade volume can cause other people to take notice. If enough people, or a large individual investor, follow along with the new trend, it can also affect the valuation of the stock, positively or negatively. This happens without precognition and is called a "run". Either people are running to the stock or away from it. If the run is bad enough, the people monitoring the exchange can cease trading that stock to prevent serious market problems. These problems can kill a company if they are serious enough. They can also seriously affect the future of the stock even after the run ends. # So what happens when you have someone who can predict the future? There's a couple things that can happen. A careful/moral investor will make sure their decisions don't seriously affect the expected price by their interest in that stock. They will purchase and sell modest amounts of stock, maybe through intermediaries, and try to prevent runs that cause havoc. They notice an expected rise or fall in prices and invest accordingly. An immoral investor will try to game the system. They will purposefully cause the stock to be noticed and try to get the price to rise unnaturally, then sell before trading stops or the price takes a nose dive. They will notice a natural rise or fall in prices, then make massive purchases or sales in an effort to make it more drastic and to their advantage. A newbie may unintentionally cause stock prices to unnaturally rise and fall, but will simply be inexperienced on how to prevent this. They may lose as much money as they earn. They may also lose considerably more than they earn, simply by not paying attention. Then again, that I've explained happens in today's market. The only difference is that we currently work on historical trends instead of future/expected trends. # There's a problem... and complications... Unless your Universe is pre-destined to everything, then current decisions affect the future. If you've ever seen the movie "Next" with Nicholas Cage, you'll know that a precog might be able to "try" different things to cause an expected outcome. In the movie, Cage is able to project himself into the future a variable amount of time, seeing what happens, then changing how he progresses. This is useful to him as he can now predict when and where he is shot, in one scene, so he can effectively dodge the bullets before they are fired. It may not be the best movie around, but it does make you think about how effective being able to see into the future may be, or not, depending on your intelligence. Are your precogs able to "see" the changes they make in the timeline in "realtime" or are they effectively as blind as anyone else to their purchases and sales. If they see a price go up or down and they make a significant purchase or sale, does that price they see match the price at the time actually forecast? Asked differently: if they look again, does their "vision" change? Can they even look again or is that same instant in time blocked from them somehow? Is it only a function of energy whether they can look forward and how long is their recharge time? This kind of meshes with how far into the future they can see, because if their cooldown is longer than their pre-vision, they might not be able to change their decision anyway, unless there's partners or a team making sure the decisions are correct. # Conclusion So, does your stock purchase change the future? Can you "ride the wave" of someone else's run and get out before you get stuck? Or does one of your characters realize that precog doesn't change anything and therefore doesn't really matter (pre-destiny)? Maybe there's another set of precogs that work to prevent runs on stocks and effectively "normalizes" the market? Maybe the market is regulated so that only a certain amount/type/size of unnatural market fluctuation are made before a specific individual is required to get more education or is outright banned. This is your story, so you have to decide what what you want to happen. If you want to make the stock so dangerous that only a fool or genius would participate, you can do that. If you want it to be so regulated that only "masters" allowed to use real money, with everyone else being on a virtual market until they become "certified", you can do that, too. Maybe the stock market was so volatile that it crashed years ago, and no there's only stories/myths about it and how people went mad trying to use it. Hopefully I provided more insight than questions. "Have fun storming the castle!" [Answer] They would totally work in [arbitrage](https://www.investopedia.com/terms/a/arbitrage.asp) with total approval of the government --- reducing volatility, they lower the average cost of borrowing across the market and thus provide a useful service. I was always abhorred by the idea of arbitrage (literally making money from nothing; boils down to having an internet connection and hardware that's a few milliseconds or fraction thereof faster than the rest), but beyond that it has a stabilizing effect. ]
[Question] [ In this scenario people are in a constant war on an infinite flat world with the geography of Antarctica's interior (but with no liquid water or hydrocarbons). Notably this world has an abundance of deposits of radioactive ore and the people are decades ahead of us in some areas like nuclear tech, as well as having shadow magic that can create very effective shielding and cheaply separate isotopes. This world experiences a universal 1 G acceleration, but while other physics are the same there's no "true" gravity. This also means that gravitational sensors can't work. The scale of conflict means that people need to build a lot of transport vehicles as cheaply as possible and having to set up a new settlement and move isn't uncommon so it should ideally be as easy as possible to set up new factories. Not having the transport vehicle compete with military vehicles for minerals or rare components is also strongly desired here where possible. What sort of nuclear based transportation would be best suited to cheaply transporting large amount of cargo at decent speed over Antarctic geography, if radiation weren't a concern? For these purposes something like the [Antarctic Snow Cruiser](https://en.wikipedia.org/wiki/Antarctic_Snow_Cruiser) doesn't remotely cut it, the people here want way more carrying capacity and speed. Importantly people in this world don't really need to worry about any radiation that wouldn't rapidly kill them: Due to a combination of biotech, and using shadow magic to shield against radiation and separate radioisotopes. Shadow magic wards can also be used to shield mechanical components against radiation, but this gets costlier the better the absorption needs to be (so you're not blocking a direct nuclear strike with this). In order to not let radiation reveal one's activity/position, people deliberately set off large numbers of nukes and fly around drones that spray nuclear fallout behind them. In order obscure their location and activities (like them using nukes for tunneling). Propulsion options I've considered but can't decide between include: * Nuclear saltwater rockets (I strongly suspect they may not be practical for this application). * Nuclear thermal rockets (seem like a better option than the saltwater rocket, but it is still a rocket so idk, also seems worse than a ramjet because of the propellant's weight). * Nuclear reactor power source for electric propulsion like jet engines. * Ramjets which directly use nuclear material to heat up air generating thrust like [Project Pluto](https://en.wikipedia.org/wiki/Project_Pluto). This option seems like it might be the most promising since I've heard ramjets are simpler than regular jet engines. * Nuclear steam-craft are an idea I had where a vehicle sucks up snow with a fan/scoop and then flies around over the ground on jets of steam (I have no idea how viable this would be). I guess this might technically count as a type of NTR as well. [Answer] First, I'll address why I think some options will not work. ##### Rockets Because your world is an infinite flat plane, rockets are impractical (even if there is a 'space') - without a body to orbit around, they lose most of the advantages of going to space. * Nuclear thermal rockets are right out, because their thrust-to-weight ratio is far too small to take off, and they still need fuel (hydrogen, usually). * Nuclear Salt Water Rockets are better, but since they would likely be designed as aeroplanes (can't orbit), they would then spew tens of thousands of tons of highly radioactive exhaust into your atmosphere.† (Even if it did reach space, because orbits are impossible, the exhaust would eventually just fall back down into the atmosphere too.) * Lithium Salt Water Rockets are better, because their exhaust is not radioactive, but they are much more challenging to make than a standard NSWR. * However Nuclear Salt Water Rockets are probably not what you want - I doubt you need to reach speeds of 3% C when transporting military equipment, not to mention you would evaporate because of atmospheric heating. †You have mentioned that it is easy to shield against and treat radiation issues in this world, but even then, unless your people are all just entirely immune to radiation all the time, it would still be better not to dump radioactive material everywhere. ##### Ground-based Ground-based solutions have problems not only with infrastructure requirements, but also that damage to said infrastructure is an easy way to render them useless. * Trains. With apologies to a couple of the other answers, I think trains are the worst option. Look at how armoured trains have fared in warfare in the past. When their rails are damaged, they become worthless. Especially since you have asked for speed, you need very well-maintained rails (see TGV, Shinkansen, and similar). * Road or Off-Road: Better than trains, but slower, and (usually) unable to carry as much cargo. If the vehicle is designed for off-road work then significant damage to the road is required to stop it. However, it can be stopped by cliffs, walls, ravines, etc. A determined enemy will use all of these. * Hovercraft: These are generally a good option for snow and ice, because they cannot easily get stuck. Their chief disadvantage is they require fairly smooth ground. A wall or hole will stop or hinder them, and some spikes could severely damage the skirt which is essential to their operation. Ekranoplans might be a possibility (except for Type A ones - these have the same problems as wheeled vehicles). I mention them again at the end of this answer. --- Therefore, I think you are looking for an Aeroplane. And you are in luck! Such an aeroplane has already been designed: ## The Lockheed CL-1201 If you are looking for speed, range, and capacity, see the [Lockheed CL-1201](https://en.wikipedia.org/wiki/Lockheed_CL-1201): a proposal (1969) for a VTOL nuclear aeroplane of truly vast proportions, able to carry 12,000,000 lbs (5.44kt) and stay airborne for 41 days straight (without refuelling). Its wingspan would almost have been equal to the height of the empire state building (341m), and it was to be supersonic. It would have used something similar to a nuclear-thermal ramjet for power, sending all the waste heat from the reactor to a set of 186 (182 VTOL, 4 flight) engines. These would operate similarly to standard jet engines except, instead of creating heat by burning fuel, they would take heat from the molten lithium metal used to cool the reactor. The advantage is that it needs no fuel other than uranium for the nuclear reactor. This, or other vehicles similar to it, seem to be the optimal solution for your problem. --- Edit: After further consideration, I think that a [Type B or C Ekranoplan](https://en.wikipedia.org/wiki/Ground-effect_vehicle#Classification) based on similar principles to the CL-1201 might be an even better option, due to its increased carrying capacity and improved stealth over a standard aeroplane. However, it will also be easier to damage or attack than a standard, high-flying aeroplane. [Answer] In a world abundant with radioactive materials, cutting-edge nuclear technology, and shadow magic for shielding and isotope separation, a nuclear-powered hovercraft-like vehicle becomes the ideal choice for affordable, speedy transport of large cargo across Antarctic-like landscapes. The hovercraft would be driven by a compact nuclear reactor, supplying the energy required to generate lift and propulsion for efficient travel over icy terrain. Advanced reactor designs, such as molten salt reactors or small modular reactors, are known for their efficiency, safety, and scalability (World Nuclear Association, 2021). These features make them suitable for transportation vehicles as they produce significant energy with a small, lightweight core. Traversing snowy and icy landscapes is made easy with the hovercraft's design, as it doesn't rely on wheels or tracks that may become stuck or slowed down. Instead, it uses a cushion of air, created by the nuclear reactor's power, to hover above the surface, enabling high-speed movement in difficult conditions (ScienceDirect, 2021). Shadow magic's use for radiation shielding and isotope separation adds to the nuclear hovercraft's suitability. The shielding protects passengers and cargo from radiation, while isotope separation ensures continuous fuel supply. Compact reactor designs minimize required shielding, reducing costs. Modularity in the hovercraft's components allows for quick assembly, disassembly, and maintenance. This simplifies the establishment of new factories and production lines in response to the ongoing conflict's shifting demands. In summary, a nuclear-powered hovercraft utilizing advanced nuclear reactors and shadow magic offers a cost-effective, efficient, and adaptable solution for transporting large cargo at decent speeds across this world's challenging Antarctic-like terrain. Sources: World Nuclear Association. (2021). Small Nuclear Power Reactors. Retrieved from <https://www.world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/small-nuclear-power-reactors.aspx> ScienceDirect. (2021). Hovercraft. Retrieved from <https://www.sciencedirect.com/topics/engineering/hovercraft> [Answer] I can think of 3 things, going in order from most energy efficient to least energy efficient & most infrastructure needed to least infrastructure needed. Note that i'm leaning more into the move large amounts efficiently side than the speed side as these 2 things are generally incompatible most of the time. ## Electrified railway with nuclear power plants Ultimately, the most energy efficient way to get power from nuclear is large, centralized power plants. Using anything to keep you off the ground is always going to mean your going to need much much more energy that staying on it no matter how you do it. As well, electrified trains allow movement of literal 1,000s of tons of material, using multiple unit operation allows 10,000s or even over 100,000 tons at the highest end to be moved. Speed for very heavy freight trains isn't going to be as fast as anything flying, obviously. But it's also possible to run faster trains, even on non-high speed track achieving speeds up to 200kph is doable, although there is an inherent trade off between maximum safe speed & maximum safe axle loading with tracks. For an example [the Iron Ore Line](https://en.wikipedia.org/wiki/Iron_Ore_Line) in northern Sweden & Norway has freight trains moving loads of 8,600 tons at 60kph with passenger trains going 135kph. ## Non electrified railway Much the same points as above apply. Nuclear trains have been proposed irl many times & are always faced with 3 big problems, very high axle loading, safety, & cost. They are also significantly less energy efficient. It is possible but almost certainly worse than electrifying the line but it would save you the cost of well, electrifying the line. Otherwise similar to an electrified railway ## Nuclear Overland Train This is probably the least efficient & fast, but it's the only one to not need pre-existing infrastructure. Overland trains are the idea of connecting a large chain of wagons on rubber tires with a power unit to move large amounts of cargo in difficult terrain. While the only ones built irl were diesel or gas turbine powered & didn't actually work very well, nuclear powered ones were proposed. This could probably be used to move large amounts of cargo. [Concepts i can find would have been capable of moving ~150-300 tons](https://overlandtrains.com/updates/nuclear-powered-overland-trains-bonus-book-pages/) While none of these options are particularly fast, none are particularly slow i think. However they are all very energy efficient & aside from overland trains very high capacity. [Answer] Semi-buoyant steam airships. An infinite planar world with no liquid water should have particularly boring weather that would be of little threat to airships, and [hybrid airships](https://en.wikipedia.org/wiki/Hybrid_airship) could land and take off from small airfields surrounded by rugged terrain that would be impassable to ground vehicles, but are more compact and can carry heavier payloads than fully buoyant aircraft. Steam is a reasonably effective lifting gas, far better than hot air for example, with the major drawback of requiring high temperatures. A nuclear reactor would make these temperatures relatively easy to maintain, while also powering steam engines to drive lift/propulsion fans or propellers. [Answer] Scramjets are very simple... If you can get to Mach 6. Ram Jets have a similar issue - namely you need to get supersonic for them to work. This is because they use the shockwaves to compress the air, rather than a compressor. From a design point of view - you've indicated you want speed, but you also want large volumes of cargo. I'm also presuming that you have no fixed infrastructure (e.g. rail lines) which puts us in a bit of a quandry - If you want speed, you'll be flying. If you want Bulk, you won't be. To put this in perspective - a single C5 Galaxy heavy lift cargo plane can carry about 127,000 KG of cargo. In NZ the Maximum weight allowed for a Truck is 46,000 KG - so it's about 3 trucks to one plane. Then you have the issue of weight displacement on Ice and landing on ice - both of which are issues. However I think the best answer would be... A Scaled up, Nuclear powered Hovercraft Something like the Russian Zubr craft which can hold 190,000 Kg of Cargo (based on my back-of-the-envelope maths). You would run the reactor at the rear and use steam pressure to drive a generator and have all the fans on the Hovercraft be Electrical. The air cushion means that many of the issues with moving on Ice are mitigated - you aren't worried if there's a crack or a fissure, you can ride over it. We can beef up the propulsion so that we can get some speed - 200Kph might be reasonable - if we want to add some form of Nuclear powered jet, perhaps even more so. You could even have multiple Hover-barges being towed by the main unit, which would decrease top-speed, but would provide for significant cargo capacity (several thousand tonnes of cargo) [Answer] ## Land trains The US military actually planned on building it, it was called the Nuclear Overland Vehicle. It was designed to freight delivery over tundra. A giant offroad land train. Each wheel on each car powered by an independent electric motor connected to a compact nuclear plant on one car. Several iteration were built using deisel electric engines but a nuclear one was planned before the need to move so much freight across tundra fell away with huge cargo helicopters. They could ford small rivers and the huge wheels made its displacement low enough it could drive over tundra mud or loose sand easily. here is the last iteration actually built, the TC-497 Overland Train, Mk II which was almost 600ft long. It had a top speed with 150 tons of cargo of 20mph. The final nuclear version was expected to be several times longer. [![enter image description here](https://i.stack.imgur.com/Wrfuw.png)](https://i.stack.imgur.com/Wrfuw.png) [![enter image description here](https://i.stack.imgur.com/F03rq.png)](https://i.stack.imgur.com/F03rq.png) Upsides: offroad, not much infrastructure needed, probably the most cargo possibly without infrastructure. Great setting for a story. downsides: slow, offroad means 20-30mph tops. That sounds slow but that is about how a fast a modern cargo ship travels. [Answer] How about something like the Soviet [TES-3](https://nucet.pensoft.net/article/89356/)? This was a tracked nuclear power station. The article provides some idea of its intended use. It could provide power for temporary settlements, but it could also provide power for other vehicles. [Answer] Barges Barges are about the cheapest and easiest to construct vehicle per ton of cargo. With unrestricted mastery of nuclear energy on an ice plateau, it's easy to construct canals: simply melt them! The mass of a reactor on a tugboat is much less of a problem than on land or air vehicles. A single tugboat can propel many barges at once. [Answer] Consider that any nuclear reactor will generate a discernible trail, if you have cutting-edge nuclear technology you will also have cutting-edge methods of finding trails of radioactive residue. Because of this it would be very easy to target supply lines and attack them while avoiding the bulk of nuclear military power (since concentrated nuclear-powered forces will be even easier to spot). As such, you can go different ways: 1. Either there's some sort of jamming tower that can cloak radiation trails, and then there can be a lot of tension surrounding this concept. If you want to advance you either take the risk of having everyone see your travel lines, or you take it slow and build jamming towers and then more conventional methods of scouting are also relevant. It's also a statement that you're intending to advance somewhere when you create jamming towers which can fuel political tension. Also, the other side can use your own jamming towers. 2. I would suspect people would tend to avoid nuclear-powered transport vehicles because of this trail and instead use nuclear power to generate electricity, and then use electrical vehicles to transport whatever (maybe even wireless vehicles). This would be a way to circumvent the problems I stated earlier, but also creates more interesting applications for nuclear power. Say someone destroys a power plant, now a bunch of transport vehicles will have a limited time to function until they run out of power. 3. Maybe some factions will use electrical power created through nuclear technology, some other faction uses jamming towers and another faction uses some sort of shadow magic to cover its tracks, but it only works for a short while, then you have this aggressive faction that is based on some blitzkrieg style warfare. [Answer] Nuclear powered airships. Contrary to popular belief airships aren’t made of explodium, in fact even the badly designed WWII airships would be more durable than any other modern aircraft, including military ones. The problems that they suffered were the same as with regular aircraft, except that a single aircraft crash was less newsworthy than the far harder to mass produce airships. Airships are also well suited for the antarctic. At one point during the cold war the weather above the north pole became so cold that nothing could fly there except the airships with early warning radars. The drawbacks of airships can be solved with modern engineering, just like most of the problems with regular aircraft at the time were solved. A hybrid airship for example uses both lift surfaces and gas to stay in the air, if it slows down it can land like a (massive) aircraft and with vectored thrust you can land more easily and controlled. Airships also are able to carry immense loads, and the bigger they get the more efficient this gets. The speed is also different than what you might see in the movies. The Hindenburg, a giant WWII powered airship, could cruise at 126km/h or go up to a maximum speed of 135km/h. A more modern, nuclear powered take could do much better. The resilience against storms has a rule of thumb: it can handle storms where the average wind speed is the same as the maximum speed of the airship, and that was for the poorly designed pre-modern material airships. With proper weather control and warning systems as well as more modern materials and design features these could handle most storms you throw at it, especially if you land them and anchor them. Technically this lets you build entire flying nuclear villages if you want. [Answer] G.E.V. A nuclear powered vehicle for operation on an infinite flat plain. The ideal craft has to be a GEV [Ground-effect vehicle](https://en.wikipedia.org/wiki/Ground-effect_vehicle). Not only is this type of craft, versatile, fast, efficient and scalable. [They are damn Sexy](https://www.google.com/search?rlz=1C1GCEU_enUS972US973&q=Ground-effect%20vehicle&tbm=isch&sa=X&ved=2ahUKEwix6tSb_fn-AhVznGoFHZnrCBEQ0pQJegQIChAB&biw=1920&bih=929&safe=active&ssui=on)!, [Answer] Super cheap, brute force, and only marginally difficult to control... Project Orion doable with standard earth 1960s tech. big pusher plate [with your magic shielding] lots of cargo sitting on top of pusher plate.... log small nukes out a small hole in said pusher plate and blast away. Thousands of tons of cargo moved at as fast a speed as you would like at any planetary or extra planetary distance you'd care to chose. ;-) hope this helps! [Answer] A couple of notable points: With no hydrocarbons and an Antarctic environment, you have no plastics and little to no cloth except what could be grown in nuclear-powered greenhouses. It also sounds like metals are rare (based on your comment about not competing with the military). With constant war, fixed infrastructure means targets. If there's any kind of capability to strike across borders (which I can think of quite a few ways, given nigh-unlimited nuclear power) you will want some kind of mobile solution, not trains or canals, built out of solid metal, with the least metal possible and ridiculous amounts of nuclear energy. I would go with a hybrid hovercraft / barge, floating tons of cargo on a bed of super-heated steam from nuclear material lining the underside of the barge, with nuclear turboshaft engines providing propulsion. If radiation isn't a concern, just pile uranium in enough quantity and thickness and it'll generate enough raw heat to just melt and vaporize the ice below. Mind, if it gets in a crash, squishing uranium around like that might cause the vehicle to go critical. Exciting! ]
[Question] [ In the land of Dracoriri, there are dragons. There weren't always dragons, once humans were the dominant species, but then magic-an unexplained phenomenon-invaded earth alongside creatures from another world, the foremost being dragons exist and now humans have fallen into a new niche. But, as dragons emerged, a strange phenomenon was observed by humans among the new species: variable intelligence. Some dragons acted with an animal cunning, clearly intelligent but not quite sapient, incapable of speech and driven by instinct. Their eyes were dark, and as a general rule, these "darkeyes" or drakes resembled animals, like how Crashdrake resemble cassowary or how Stealthdrakes resemble Velociraptors. However, other dragons had intelligence rivaling that of humans, being clearly sapient and capable of both (human) speech and higher thought patterns, with brightly colored eyes and glowing pupils. These dragons tended to look more like how 'traditional' dragons; Silverns are sheathed in silver scales, clearly reptilian, and have a wyvern body plan, with two batlike wings and two legs, while Goldrakes are big, covered in golden scales, with two batlike wings and four legs. Got it? Good, because this is where it gets tricky. Brighteyed dragons never have darkeye offspring, they're never born darkeyed. However, darkeyed species can be born brighteyed, or can have brighteyed children, and its rumored they can even become brighteyed somehow, though no one has confirmed this or how it could happen. Furthermore, if a darkeyed dragon has a brighteyed child, it means nothing-such dragons are not in fact more likely to have brighteyed children, and neither are their offspring. I have no idea how this could work, so here I'm asking: how could this work? How could dragon intelligence be so consistent and yet so inconsistent at the same time? Thank you for your feedback, I appreciate it! Note: Thanks to Palarran for bringing the need for clarification to my attention. Many of the "darkeyes" or drakes I've envisioned so far have indeed been wingless, but drakes can and do have wings depending on species. Furthermore, brighteyes are not limited to the same body plan as Silverns and Goldrakes. As examples, two species of brighteye, Chimerake and Swordrake, are wingless, and the two are quadrupedal and bipedal respectively. Furthermore, Mesmerake, another species of brighteye, are serpentine and possess only two arms, maybe a pair of wings, and of course fins (they're based on Sirens, the fishy not the birdy kind specifically). As for interbreeding, no brighteyes and darkeyes do not interbreed. Why would they? Brighteyes have intelligence and sophistication far beyond that of darkeyes, and darkeye species are seen as inferior (for reasons that should be obvious). It's pretty much unthinkable. [Answer] This question has a simple answer, but the answer has little to do with genetics. If brighteyed dragons can only have brighteyed children, but darkeyed dragons usually have darkeyed children but occasionally have brighteyed children, and on rare occasions become brighteyed themselves, then to say that there is a genetic component may be incorrect. If we consider brighteyed (d) to be a recessive trait and darkeyed to be dominant (D), then perform the following brighteyed/darkeyed Mendelian crosses: dd × DD = 100% Dd darkeyed. dd × Dd = 50% Dd darkeyed, 50% dd brighteyed. We would also get: Dd × Dd = 25% DD darkeyed, 50% Dd darkeyed, 25% dd brighteyed. However, the OP has said that darkeyed dragons are not more likely to have brighteyed offspring (more likely than what?), and that brighteyed dragons always have brighteyed offspring. So... this can't be genetic, as even if brighteyed is dominant, two heterozygous brighteyed dragons would have 25% darkeyed offspring. Now, we don't know if the OP is considering only the mother or both parents in the statement that brighteyed dragons always have brighteyed offspring. Either way, it doesn't matter. What is something that will always be transmitted to offspring? Not a gene-mediated trait, that's for certain. How about a pathogen/symbiote? That's more likely. If we say that being brighteyed is caused by the presence of a symbiote, then the symbiote can be transmitted from mother to her children quite easily... even in a potentially egg-laying species. If the OP desires, it may also be transmitted from father to offspring if the dragons are internally fertilised. While the darkeyed parent would usually be immune to the brighteyed symbiote as if it was a pathogen, having it present since conception would make it an accepted part of an individual's body. However, a darkeyed adult may come into contact with the symbiote and may on rare occasions prove to not be immune, and may become a host, in which case a rare spontaneous adult darkeyed to brighteyed transition would be seen to have occurred. Now, if this symbiote causes dragons to have bright eyes and to be more intelligent, by whatever mechanism, that's the answer. Additionally, if this symbiote has a different set of metabolic proteins to the host dragons, there may exist a substance that is a symbioticide... that kills only symbiotes, leaving the host unaffected. In the case of being exposed to such a substance, a brighteyed dragon could thus become a darkeyed dragon. It might lose its bright eyes and/or its intelligence, depending on whether the symbiote becomes the observable trait(s) or stimulates the dragon to produce the observable trait(s). In the latter case, the trait would persist even after the symbiote was lost, but would no longer be heritable. [Answer] # Epigenetics and development: For dragons, magic is like a nutrient. They need it to survive. But how much magic an individual gets is based on the mental ability to tap into magic. A cunning but unintelligent dragon lives off the background magical radiation in the environment, but they suffer serious developmental deficiencies, lacking enough of this magical nutrient. Eye color is just a handy marker that is also affected by this same lack of magic. Those dragons without only develop into a few stunted body plans. This does not mean those dragons aren't fierce or potentially large - only that they are stunted in normal development. But since magic is altered and controlled by brain functions (like "spells," which are really simple mind tricks to harness magic), intelligent dragons subconsciously gather and manipulate sufficient levels of magic to allow normal development of their offspring. There MAY be transfer of magic male-to-female, but most likely the magic is simply supplied to offspring prior to (egg laying? Birth?). Or it could even be a transfer from adjacent intelligent adults to any nearby gestating egg. If an egg from a less intelligent dragon is exposed to a sufficient magic by whatever incidental means, then the offspring will be intelligent. So let's assume dragons have an instinctive desire for fully functional offspring. You could even have some fun with this. Perhaps dragons subconsciously kidnap well educated and intelligent humans (princesses?) to keep around their eggs on the instinctive knowledge such people tend to uncontrollably harness and shed extra magic. They might be willing to let smarter dragons gestate their eggs to increase the odds of normal development. They may even be genetically primed to leave their nests unguarded in the presence of those with magic (wizards/witches) because those potential egg-snatchers are more likely to lead to fully developed (intelligent) offspring. * In a [separate answer](https://worldbuilding.stackexchange.com/questions/187116/would-an-evolutionary-predecessor-for-winged-quadrupeds-start-with-four-legs-and/187138#187138) I addressed one possible way in which a single genetic line could give rise to a wide variety of body forms, including winged, un-winged, un=limbed (wyrm) and multilimbed body types, which may be relevant to your question and the varied body forms of your dragons. [Answer] Diet A dragon is bright-eyed if the parents ate certain foods before conceiving the egg, or fed those foods to the child. (Or both.) Vital nutrients are involved. These foods can be preserved safely. Bright-eyed dragons ensure they have a supply of the food beforehand, or they do not have a child. The thought of their child reverting to animalhood is too horrible to be considered. Or perhaps it's actually essential to a bright-eyed dragon's life, so they will die and so not reproduce without it. Dark-eyed dragons sometimes accidentally blunder into this food. Bright-eyed dragons don't care. [Answer] How about education? Dragons wouldn't necessarily be social by nature, so cooperative learning opportunities are more limited than in human society. They're also very long-lived, and don't learn as quickly as humans. So, born ignorant and at the whim of their instincts, they seem like animals. However, centuries of experience and observation may provide intellectual (magical?) development. Those that survive that long can attain sapience (power?) and communicate with humans on a level of reason. Those that had attained this threshold would likely not let their offspring roam free until they had conveyed the wisdom and power of their own learning, fearful that they're not safe enough without that knowledge/power. (Or they have some form of hereditary memory, if you prefer.) So light-eyed parents have dark-eyed children, but keep them under wraps until they become light-eyed. (Or go for hereditary memory and simplify this explanation.) But any dark-eyed individual can attain the threshold through their own efforts, or with the help of a light-eye. Why the eyes change color could be a hand-wave, or you could invent an in-universe explanation. [Answer] I'm not sure this can be achieved purely by genetics, so let's use a mixture of magic + genetics. > > At first all dragons where drakes; then suddenly and seemingly out of > nowhere an intelligent dragon (simply "dragon" from now on) hatched > from an egg\. It grew up realizing it was different, and thought to be > unique until suddenly another dragon hatched from a drakes' egg... and > then another... and then another... > > > These dragons, being so different, began to separate themselves from > the rest and form their own "society". Being intelligent, they soon > started their research to find out why and how they where born > different, and realized that, at some point of the year/season/month, > a wave of magical energy crossed some areas of the world and, if a > drake's egg was exposed to this magic wave, the unborn offspring would > eventually hatch as a dragon and not a drake. > > > \assuming your dragons are oviparous; this is not mentioned in your question but it's the way its usually represented For the point that all dragons' offsprings are dragons too, I think of two possibilities 1. The traits that this magic energy give to drakes to make them dragons are indeed imbued into their DNA, so it is inherited from the parents. 2. Having found out how this magic wave works, they started to control their mating seasons so every time an egg was laid, it could be exposed to this magic to ensure a dragon would hatch from it. It is not allowed (and frowned upon) to lay an egg outside the "magic wave season", and no dragon wants to have a drake so everyone complies to this rule without hesitation. [Answer] in Beowulf's Children , the sequel to the legacy of Heorot this was done by one of the creatures visiting a pool by accident as a youngling and picking up a parasite there. A parasite gives them a brain inflammation that changes their pathways as they grow, causing their brain to grow differently than the rest of their species. Like encephalitis or similar. Though I may be misrepresenting the story. There the creature becomes aware of this and decides to force it's children through the same process to allow them to be more than just an animal. (Since it can reflect and plan while the rest of it's species mostly just reacts. and the fact that they can plan means they have a huge advantage over the other. I'm not sure if this is exactly how it went it's been a few years but that's the gist of it. A parasite / illness could cover your scenario, especially if you don't want the children of such a creature to automatically be intelligent. It also opens up the option that with effort you could reproduce it. (possibly at some risk to the subject) [Answer] This basic idea was already used as part of the plot in Marie Brenna's series of "Dragon naturalist" novels. In those books, one thing that strongly affected the size, color, and intelligence of some dragon species was the incubation environment of their eggs. This has real-world precedent among some reptiles and amphibians. You could easily use the same thing ... which would also provide a mechanism for the humans to either exploit or supress dragon brighteyed traits. [Answer] ## It is just a hitchhiker Eye color has nothing to do with intelligence, it's just a [hitchhiker](https://en.wikipedia.org/wiki/Genetic_hitchhiking) mutation, meaning that it doesn't effect fitness or reproduction rate, it's jut randomly associated to another gene which causes a huge fitness boost (let's say that this gene is responsible for intelligence). The darkeyes and lighteyes don't mingle with each other, so it could be possible that the small population of dragons which were the ancestors of all the smart ones were by chance all homozygotes to the lighteye gene ([Founder effect](https://en.wikipedia.org/wiki/Founder_effect)) and the phenotype remained because of interbreeding. Even some sexual selection could've helped for the phenotype to subsist, nobody wants to mate with that guy who has the dark eyes of our dumb cousins, am I right? If we assume that the lighteye allele is recessive to the dominant darkeye allele, that would explain the random lighteye offsprings of the darkeye dragons especially if the gene's mutation rate and the number of lighteye alleles in the gene pool are both low. So there's a low chance for the formation of a new lighteye allele and it's unlikely that the homozygote lighteye will meet another homozygote (or even a heterozygote). [Answer] Diet Just being big is expensive in terms of energy. Flying is much, much worse. Breathing fire doesn't help. Being intelligent, on top of that, is ridiculously expensive. A huge percentage of our calories and inhaled oxygen goes directly to our brains. For a dragon to end up intelligent, the parents (intelligent or not) must have access to huge amounts of energy in their diet. If they don't the genetic switches that control things like big brains, fire-breathing and flying get shut off in succession. Once the egg develops, you're set for life with what you have. This is the overall genetic plan for survival. It's the only way to survive the lean times while conferring advantage when reasonable. Once you gain intelligence, you have the ability to figure that out and to plan ahead for your kids. Assuming you want the competitors ... [Answer] Borrowing from the Schlock Mercenary [Kreely](https://schlockmercenary.fandom.com/wiki/Ice_Kreely) species, sentience is the result of an infection at an early age, stage of gestation, or exposure of the egg. All dragons can be carriers of it, but within the Darkeyes, it doesn't survive as long after exposure. Thus, for a given Darkeye, they may be exposed to the infection and pass it along to their offspring, but generally they develop "normally", but for the Brighteyes, their system incubates the infection and thus their children are always exposed to it at that early stage. Eventually, this may lead to the Brighteyes realizing that interaction with the Darkeyes (possibly during battle) is what results in Brighteyes being born into Darkeye broods, and either intentionally suppress that infection during interaction to prevent Brighteyes from forming, or engage in something closer to genetic warfare by influencing more Darkeyes to brood Brighteye young. Eventually, as with the Kreelies, it may lead to them intentionally maintaining two lines of the species, one intelligent and one not, especially if the Darkeyes are useful as pack animals, meat sources, etc, not to mention the possibilities of Brighteyes trying to ensure that the "right sort of dragons" are the ones given the chance at intelligence and they can maintain their unintelligent slave labor force. ]
[Question] [ I'm developing an alternate Earth where super spies exist. Men and women of extraordinary skill with extraordinary gadgets who act in extraordinary ways to protect the proverbial "King and country." They're so common that your average insurance policy has an "accidental victim of collateral damage due to international espionage" clause. And, like all good super spies, their stuff is just a little bit better. * Technology available to the spies is smaller and lighter than what would be available to a corporation or "publically" available to a government in the real world in 2021. By that I mean, for example, that while a parachute that your average goombah can buy would weigh 10kg, your aveage super spy's would weigh only 5kg with corresponding reductions in volume, size, etc. * Technology available to spies (TAS) would also be a bit more powerful. That average goombah's pistol might throw a 7g slug at 350 m/s, but the spy's would throw the same slug at 500 m/s and be half again as accurate. * Similar improvements will be found in all gadgets available to the spies. Above all, it's absolutely amazing what the super spies happen to have on them at any given time. Their quartermaster is remarkably foresightful! So, here's the question: Our daring super spy is running for his or her life... only to discover a ravine! Can't turn left or right... the dogs will rip the spy apart! The only option is to jump/swing/fly/swim/belly-flop over the ravine! In style! (of course...) What tool can our spy's quartermaster provide to help the spy escape certain death and win the day? 1. This is a tool-development/technology-development question. You're designing a tool. 2. You have the technological limitations listed above. 3. The solution must be light enough to be carried by an athletic person at a full run for at least ten minutes (it's amazing how much ground a super spy can cover in just ten minutes!). I'm not worried about gender. If you can cite an example of any person who, as an example, can justify the solution you're proposing, you're on! (And that person's alter-ego in this world is probably a super spy, anyway. I'm lookin' at you, Grace Jones!) 4. The ravine is 50 meters wide and deep enough that if your solution doesn't work, the dogs won't matter. 5. While a use-once solution is acceptable, a reusable solution will be favored for "best answer" selection. 6. The most *outrageous* solution will take the green checkmark! By "outrageous" I do *not* mean "rube-goldberg." We're not looking for overly complicated. We're looking for clever you-wouldn't-see-that-on-the-shelf-at-Walmart type stuff. Clarification: Your solution is a working piece of equipment that was checked out from the quartermaster. I'm looking for creativity and some quirkyness, but the winning solution won't be "the spy found A, B, C, and D along the route and happened to fashion a tightrope and balance bar out of it." 7. BUT! The solution, while likely entirely implausible, can't violate the laws of physics. The solution might be impractical, possibly even impossible to reasonably build using the real Earth's 2021 technology, but the concept can't violate physics (which means inventing something like a couple of pounds of "gravitonium" kept in a magnetic container that, when removed, will lighten his body weight by 95% and allow him to jump the ravine... well... that dog won't hunt). [Answer] ## Pole vault Your spy is a distinguished gentleman who carries a fashionable cane with a precious metal head. The head will be the focus of another escape, but for now the cane itself is fashioned after the form of [multi-walled carbon nanotubes](https://en.wikipedia.org/wiki/Carbon_nanotube). With the right authentication it can instantly elongate to many, many times its original length, and the multiwalled tube structure still gives it substantial stiffness. (The electrical power source that drives the elongation can also be adapted to propel fast-moving objects down the tube by electromagnetic induction, but we'll let him use that to deal with the dogs on the other side of the ravine...) [Answer] Zip-zip line. A small belt- or purse-carried (or included in a shoe?) module projects a small diameter, lightweight, but super strong line up to a couple hundred meters, where the (smart) grapnel will loop around something solid (tree trunk, power pole, etc.) and hook back to the line (just like in the movies). A secondary line can be pulled back from the belt module to securely wrap to a similar solid object, and the projector then first draws the line taut (this line had better be graphene nanotube based; we're about to stress it to improbable levels), then converts to a powered zip-line traverse that carries the spy across (even if the far end is up a bit, or not down far enough to coast at a useful speed). Once across, the traverse module ignites the line which, because the cores of the nanotubes are filled with a strong oxidizer (pure oxygen, at a minimum), burns away completely in just a couple seconds, so the pursuing enemy can't follow. Better run, Super Spy! --- [![elemtilas](https://i.stack.imgur.com/BdnP8.jpg)](https://i.stack.imgur.com/BdnP8.jpg) [Answer] Rockets, unlaunched. Your spy has a rocket launcher. This mission called for that. Fortunately she only used one rocket and so has 9 left in the magazine. It is fortunate that it has a magazine because she is going to use those 9 one after the other. She wraps her beach towel around the rocket launcher and jams the exit, then fires. The rocket is prevented from leaving the launcher and the exhaust carries her up at an angle out over the ravine. She clears the spent rocket and performs the same maneuver with rockets 3 through 10, so traversing the ravine. Fortunately the beach towel was damp, but by the time she reaches the far side of the ravine it is smoking and catches fire. One snap extinguishes it and she takes it with. The empty rocket launcher is left behind. Also her flip-flops which fell off into the ravine. [Answer] ## A hang glider built into his suit jacket. As our hero approaches the edge of the ravine, he whips off his suit jacket, pulls a telescopic rod from its inside pocket and extends it through the sleeves, then pulls hard on one of the buttons. Immediately, the jacket interior unfurls into a mini hang glider. He slows briefly to a sort of jog as he wraps some newly-exposed straps around his midsection, then resumes a full sprint. When he's only a few strides from the edge, he casually drops a mini smoke grenade on the ground to cover his escape. As he leaps off the edge at full speed, he deftly slides his feet into the final strap as the glider fills with air and begins to soar. The dogs chasing him run full tilt into the smoke and only just barely manage to avoid accidentally running over the now-obscured edge. A young henchman is not so lucky, however, tripping over one of the dogs and letting off a Wilhelm Scream as he tumbles into the ravine. The remaining pursuers stop just short of the smoke cloud, weapons drawn but unable to see a target. By the time the smoke clears, our hero is well out of range, although that doesn't stop some of the henchman from trying. The enemy leader arrives at the scene just in time to see our hero reach the other side. With his feet back over solid ground, he yanks on the tag inside the jacket, causing it to release the straps and begin rolling back into a normal jacket. Simultaneously, he presses a button on the end of the telescopic rod to collapse it back into his hand, which he casually slides through the sleeves, allowing him to land on the ground properly wearing the jacket again. He slides the rod back into the inside pocket, fixes his tie, then gets on a motorcycle that an ally had conveniently hidden behind some nearby shrubbery in preparation for the mission. He revs the engine, then turns back to his enemies, gives a smile and a mocking salute before riding off into the sunset. [Answer] Micro-thrusters, Wing-Suit, and Velcro-gloves A combo move always looks cooler than a single one. My Spy running at full speed, hunting dogs about to take a bite at him, jumps into the ravine, deploys his integrated [Wing-Suit](https://en.wikipedia.org/wiki/Wingsuit_flying), when it looked like he couldn't make it, fires a set of micro-thrusters under his shoes, reaches the other side cliff wall and clings to it using his velcro gloves. Or if we can get external help, why not use a Sky-Hook Have you seen that batman movie, where batman kidnaps the bad guy from another country, using a skyhook. Same style. [Answer] Simple answer is a small parachute to get you across like a glider without dying, and then some climbing gear to get you from the cliff-face to the top on the other side, be it a grappling hook you attached to a bush while in the air, piton alternatives, or just plain badass bouldering. My small brain can't really think of anything else. --- Oh wait, I got another one. What if he somehow gets one of the hunting dogs, deploys a parachute as a glider, and then [hammer throws](https://en.wikipedia.org/wiki/Hammer_throw) the dog over the ravine while holding on to get himself further. Then repeat the above. Method of obtaining the dog not included [Answer] Well, clearly you want some type of jetpack. [This kind](https://www.youtube.com/watch?v=EAJM5L9hhBs) has been in the news lately. Reduce the size by half with super-spy tech. If your spy is only interested in short 50m hops, the amount of fuel carried can be reduced to a minimum. In order to make the jetpack more "unique" and possibly lower the weight, perhaps you could reduce the size of the jetpack further so it's just a single use solid fuel rocket. The rocket carries them across but has no landing capabilities. Add a small parachute so they don't break their legs on landing. (Or a concealed wingsuit that pops out of their clothing between their arms and legs, which would be less practical for landing but maybe more fun). Such a rocket would be incredibly dangerous to use or train with. It could come with a guidance computer that automatically angles the nozzle to improve stability. Or the spy can just be that good. [Answer] [Ballooning](https://lbourouiba.mit.edu/sites/default/files/documents/2017-MathBio-Balllooning-LMLB-1.pdf) International Super Spy John Done is sprinting away from the secret lab, microdots of data safely tucked into his shoe. A tingle on his neck warns the super spy an instant before it is too late : the ground has given way to a chasm five stories across. What's this? A loose thread? John Done tucks at the tiny dangling fashion faux pas at the edge of his cuff. With only a tiny tug, the thread starts to give way. Agent Done holds the growing thread as it kites up in barely moving air. The super spy dons a glove that gives the tiny microfiber just enough charge to produce useful lift. Before the facility guard dogs can arrive to tear him to bits, John Done has once again escaped certain death as he flies away like a spider on a thread balloon across the chasm. [![enter image description here](https://i.stack.imgur.com/zi29zm.jpg)](https://i.stack.imgur.com/zi29zm.jpg) [Answer] ## ACME Sproing Boots! [![enter image description here](https://i.stack.imgur.com/gdJIBm.jpg)](https://i.stack.imgur.com/gdJIBm.jpg) See them in action: <https://youtu.be/jo24NR7e4ew?t=113> Obviously, any good spy agency will employ a cadre to ensure that the springs are properly integrated with the footwear and function perfectly at need, and that the spy is properly trained in their safe use for launching, for landing...and perhaps occasionally as an aid to intimacy. [Answer] # Explosion Assisted Human Cannonball Glide Equipment Needed: 1. Shrapnel Resistant all purpose Vest: Really what spy isn't shot at? 2. Explosives: A good spy never leaves home without them. 3. Wing Suit: Standard issue for any spy working at heights. 4. IAFAS: Instant Airbag Fall Arresting System. Like a car airbag it explodes into an extra large cushion which is safe to land on for less than 1 second. Standard issue for any spy working at heights. Procedure: 1. The spy improvises a Human Cannon using the vest to protect her from the blast, and the explosives to propel her. She also uses materials available near the ravine, Hollow Logs, rocks, dirt, or just digging it out if she has time. 45 degrees being the optimal angle for her trajectory. 2. The spy detonates the explosives and uses the vest to ride the blast, near the highest point of her flight, she deploys her wingsuit for added distance and identifies her landing point. 3. The spy arms the IAFAS and throws it from a height of 10 m (as per the instructions) at her landing point, the IAFAS explodes on impact, allowing the spy a relatively safe landing a moment later. Notes: 1. The world record for human cannonballs is right around 60 m, so a spy in a wingsuit could certainly manage 50 m. 2. The improvised cannon is certainly a point of failure, and is likely to kill the spy more often than it works in the intended way. But... nobody said being a spy was easy or safe. 3. Hearing protection is recommended due to both the explosion as well as the deployment of the IAFAS. Otherwise the result is likely to be a deaf, but not dead, spy. 4. The pursuers will likely assume that the spy has not survived the explosion and will no longer pursue. Most of the time they'll be right. GROOVY SUPER SPY TIP: Faking this maneuver and hiding in a place insulated from the explosion is a valid method for evading pursuit without crossing the ravine. See Note #4 above. The smell of the explosives is typically sufficient to throw the dogs off your scent. This method is arguably a safer option. P.S. When faking the maneuver, arm and throw your IAFAS into the bottom of the ravine. [Answer] The smallest parachute ever used in a landing in which the user survived had an [area of only 3.25 m22](https://www.guinnessworldrecords.com/world-records/88729-smallest-parachute) (~25 square feet). It was used by Ernesto Gainza in 2014, and [you can see a video of that here](https://www.youtube.com/watch?v=NMw19SwOKI4). Your spy could use an enhanced version for base jumping. Once in the water, the spy can use a small PADI [diver propulsion vehicle](https://en.wikipedia.org/wiki/Diver_propulsion_vehicle) to propel themselves in the water. In the picture you can see a relatively small one, your spy could have an even lighter one with better mileage in the same backpack as the parachute. [![A woman using a diver propulsion vehicle](https://i.stack.imgur.com/D5AfZ.png)](https://i.stack.imgur.com/D5AfZ.png) [Answer] Every spy these days carries a surveillance drone. Couple of kilograms of thrust, 15-30 minutes of endurance, live action HD camera, the lot. Nowhere near enough to carry our hero across the ravine, naturally. But ours was also installing a more permanent surveillance system (six camera angles, pan+tilt, all wired to a control system/transmitter/nuclear(RTG)power source in a briefcase (spies do still carry briefcases, right? and umbrellas?) for long term surveillance. None of which helps ... except the spool of wire in his hand when the hounds pick up the scent. On the ravine edge he has just seconds to hook the spool to the drone, so it's freee to unroll the wire, and pilot it across the ravine and arf! arf! dance it round the tree opposite arf! arf! how does the knot go again? the rabbit comes out the hole, and round the tree? arf! ARF! ARF! no, the other way round the tree! GRRRR! and back down the hole... SNAP! OW!!! haul in the slack, tie it to the tree at this end roll credits and fade to black ... I'll finish this answer, same time next week... [Answer] Frisbo-Matic Spy Step Introducing the Frisbo-Matic Spy Step; A tool any serious spy would never leave HQ without. Easily concealed under a dinner jacket the FMSS can be deployed in seconds to allow crossing of challenging obstacles such as rivers, ravines, shark pits and more. [![enter image description here](https://i.stack.imgur.com/UnsTK.jpg)](https://i.stack.imgur.com/UnsTK.jpg) To deploy the FMSS simply toss the device as you would a frisbee. This action awakens the internal computer and activates the 8 internal rotors allowing the FMSS controlled flight(like a drone). Upon awakening the FMSS computer will link to and monitor the precise position of the two individual shoe sensors(one in each shoe) that the user will be wearing. The FMSS computer will calculate and execute the movement of the entire FMSS unit to maintain a position under the leading foot of the user. After deployment the user will begin to run with large bounding(jumping) steps toward the obstacle they wish to pass. In the example of a ravine, the user would bound run towards the ravine and deploy the FMSS as they approached the edge. As the user continued and bounded over the edge the FMSS would position itself under the users lead foot allowing the user to land on it and bound the next step. The FMSS is powered by 8 Spy Class motors working together to deliver a peak thrust powerful enough to momentarily stabilize the platform and up to 220 pounds weight at each land / bound cycle. Immediately following the bound phase the FMSS moves to the next position under the new lead foot allowing the user to continue taking bound jumps until the obstacle is crossed. With practice a user can even use a FMSS to clear a wall. Of course that's not all, the FMSS can make difficult satellite connections a thing of the past. Simply flip the FMSS upside-down, point skyward and connect it to most any transmitting device. NEW AND IMPROVED The upgraded 2.0 model features improved shoelace proof intake grating. Now you can worry more about the mission and less if your shoes are tied. ]
[Question] [ In this science fiction universe, that has somewhat tough science in it, [paragravity](https://en.wiktionary.org/wiki/paragravity#Noun) is an established technology that is used to its fullest potential. Which lies the problem where warfare is concerned. You see, if you have paragravity, then you have access to ridiculously efficient weapons of war. Kinetic weapons that can be accelerate to a high percentage of speed of light (c) with ease, ultra efficient gamma lasers that use paragravity fields to blue-shift red lasers, missiles that are boosted by the mother ship with repulsive beams of anti gravity, particle accelerators that could bring any particle to 99.9% c. Not to mention the possibilities of inertial dampeners and other such ground breaking innovations in manufacturing and what not. The issue is that such paragravity fields that make this possible are the also the ones to shield against. Create a bubble of shifting gravitic eddies to slap aside kinetics, particles and missiles; and deal with gamma lasers be red-shifting them into a harmless wavelength. Now, while such paragravity drives produce respectable amounts of heat (the first few prototypes blew up due to how inefficient they were), any admiral or captain worth their salt would make sure any radiators are protected which can lead to battles that would last for days on end. That, of course, is boring. So I'm wondering if there is a flaw in my thinking. And if there is a way to defeat paragravity shielding. Some specifications on paragravity and paragravity shielding: * While paragravity forms into a spherical shape, it can be molded into nearly any desired geometry and into beams that can both repulse and attract are relatively short ranged (50 km to 100 km, depending on the power input). * Paragravity can both repel and attract. * Paragravity generators require constant energy to function and produce heat as well. * Shielding consists of a grid of generators that produce a field of paragravity eddies that redirect the momentum of incoming weapon fire to the side while lasers are dealt with by increasing localized sections of the shielding to red-shift the incoming lasers. * Due to the nature of the shielding, it can only be brought down if a sufficient number of generators are taken off line. Which is easier said than done. [Answer] Slapping aside a inbound projectile usually takes more energy than it took to accelerate it If you try to slap aside a projectile once it gets too close to your ship, it means you need to slap it aside at relativistic speeds to make it miss. So if you have a 100m ship and you try to slap aside a projectile that is 100m away, you have to push it just as hard sideways as it is already coming in to make it miss, and you have to do that over the entire 100m path of approach. So just make the field bigger and it takes less energy right? Well this absolutely will not work. Let's say you make a giant 400m field that accelerates a sizable attack at 0.25C, you will be protected, but it's energy requirements will be HUGE! This is because the weapon will only traverse a very small part of the field. Your field will occupy over 2 million m^3 but if the slug or beam is only 1cm wide, then only 0.04 m^3 of that field is doing any work. That is a LOT of wasted power This means the only viable countermeasure is to see where the projectile is coming from and to project a countermeasure that is just big enough to intercept it, but if the thing is moving at .95C, that is MUCH easier said than done because it is already 95% of the way to hitting you before the light from it even reaches your sensors. So lets say your computer and shield systems are able to react really fast, like in 1/20th of a second, that means your shields will only be effective at ranges of > 1 light second... and this is assuming the ships themselves aren't zipping around dodging at relativistic speeds way more effectively than any shield could ever protect you. Either way, this means that space battles will be a challenge of trying to get close enough to spoof the enemy's countermeasures but staying far enough away for your own countermeasures to have time to react. [Answer] Energy budgets Paragravity is scifi but you can easily calculate energy budgets. Let us say a 5 kg bowling ball is incoming at 0.95 c. It has 225 petajoules of energy. To bring it to a halt, your deflectors need to expend that much energy and that is regardless of how they work. You have specified that the paragravity deflectors require energy. In your world paragravity deflectors can deflect anything if they are supplied with enough energy. Attacks need to overpower them. To do that the attack needs to put in more energy than the generators can provide to oppose them. [Answer] Fire a paragravity generator The problem is that there are many gravity wells that attract and repel, allowing things that are going at respectable speeds of C to be knocked out of the way. Space it big, so likely the objects fired will not hit, even if the change in direction is small. It's like hitting a single straw with a magnetic needle over a kilometer distance, but with attracting and repelling supermagnets all over the place. It's really difficult to hit anything. So you'll just counteract the gravity generators. Fire an object like a huge rocket towards the target. A gravity generator on board can either propell it or just be idle until paragravity is found. It'll directly counteract them, like a noise cancelling headphone does with sound. It'll allow safe passage, hopefully. When close enough it'll detonate it's payload/accelerate to devastating speeds/create paragravity in the opponents ship/overheat on purpose/something else damaging. The paragravity generator can be counteracted and possibly destroyed, but in the meantime you have an area of less paragravity activity where you can fire and possibly get through. Fire once, fire twice The paragravity wells are likely not to shift too quickly. That means firing in quick succession can lead to knowing how the paragravity is positioned and how strong, allowing to calculate a trajectory to hit the enemy ship. [Answer] The really good ship defense against those weapons would be really fast really random moving. But that isn't even an issue, as there wouldn't be any ship battles using this technology, or there wouldn't be any civilizations. This is [M.A.D.](https://en.wikipedia.org/wiki/Mutual_assured_destruction) scenario. When someone's flotilla defeat is assured, they'll scatter and accelerate several dozen moons at their leisure at .99C to your homeplanet. As @Nosajimiki correctly notes, your home planet wouldn't be able to defend iself. The only way the paragravity might survive is if it required really huge machinery (I'm talking hundreds of square kilometers at least) and/or incredible amounts of energy (like quarter of the full sun output), so it can only ever be used planetwide (and that only with decades of building [dyson spheres](https://en.wikipedia.org/wiki/Dyson_sphere) in advance). Otherwise, first mad dictator will simply annihilate rest of civilizations in a universe in less then a month, simply not to feel threatened. [Answer] ## You can't see out when it's active. David Weber's Honor Harrington series touched on this a bit with grav wedges: if you tried to look through a grav wedge, it was basically impossible to get any kind of targeting information because any sensor readings were so distorted they were useless. It was handwaved that the defender could see through it via knowing the frequency technobabble. But supposed they couldn't. The distortions provided by the shielding are so effective that energy attacks coming in are dissipated and physical objects torn to shreds and rendered harmless, but sensor readings are likewise blocked. A shielded ship is essentially immune to attack (until the heat gets too high and/or energy too low), but it can't see through it, or shoot out, or communicate, either. So full-globe shielding might make you invulnerable but you're blind, deaf, and have no idea what is going on. Logically, therefore, you can't protect the entire ship at once, not if you want to be situationally aware, or even shoot back, or even know what the rest of your fleet is doing. If the shield has to be down somewhere in order to carry out the basic functions of seeing, shooting, and talking, then a saturation or multi-vector attack can find those gaps before the shield can be adjusted to plug them. Or perhaps you force the defender to make a choice: do they adjust the shields to deal with the main guns of the major enemy units, thus allowing smaller, more agile (but weaker) units to get in behind and rely on point defense or covering allies to deal with them, or do they take the risk they can deal with the smaller ships before the incoming fire from the big guns? Or split the shield, hoping that the gaps they do allow doesn't allow someone or something to slip through? This also allows for fleet actions. You have units with strong shields forming a wall, with other, unshielded, units behind them. At predetermined times gaps open in the wall to allow the covered units to fire through before closing up again. Small scouts act as eyes around the wall, basically unshielded as they have to see. The goal of fleet actions will be to try and blind the enemy (probably doing the same thing) so you can move your firing units behind the shielding ships and fire from different positions, or to launch flanking attacks to force the ships of the wall to try and protect from different directions and force the fire-support units to raise their own shields, reducing their ability to fight, and thus breaking the shield wall. [Answer] This was originally a comment but I now think it may also provide an answer, so here it is... The only way I can see how to blueshift a laser by a point-source gravity field is by shooting the laser, and then accelerating the point-source in front of the laser beam along its journey. The laser constantly "falls" into the gravity well and blueshifts, until the point-source is turned off. If you shoot a laser through a stationary point source, the laser light will blueshift on its way in and redshift on its way out, with zero net frequency shift afterwards. Anyway, if you can position these things at near- or faster-than- light speeds, I see no way your enemy can predict them. Fire superluminal gravitic influences into your enemy and disrupt their systems cataclysmically. Your gravitic eddies comprising the gravitic shielding would have to bend space to ridiculous magnitudes to avoid high-c influences, which may be too taxing to run at all times. [Answer] The way to defeat point defenses is to throw more at them than they can handle. Against shields, the attacker is in the advantage. A shield has only a very short distance in which to change an incoming objects trajectory, while the attacker can accellerate its missiles for a long time. To red shift lasers, you need just as much energy as the laser looses. So - just fire more lasers, preferably simultaneously. Brute force saves the day. (or ruins it, depending on POV) [Answer] Para-Gravitic Jamming/disruption It turns out that if you overlap paragravitic fields without 'aligning' them first, strange things can happen and, worst case, a destructive gravitic resonance can build up. The more paragravitic projectors you have, the more complex the potential field interplay is and the more computational power you need to keep the complex mesh of fields working together and redundant (so generators can fail without taking down the whole thing). This means that a large battleship with dozens or hundreds of field generators has a powerful computational core which manages the field and adjusts it constantly. Unfortunately, this field-interplay has some knock-on effects. If, for example, a shuttle craft with only one or two paragravitic generators wants to dock with the main ship without the main ship powering down all their shields, 'inertial compensators', artificial gravity, weapons, etc, the fields first need to be 'aligned' so that the shuttle's artificial gravity doesn't mess up the complex computational balance that the bigger ship has set up. Best case, there would be some shuddering and people aboard would feel nauseous, worst case a self-escalating gravitic resonance builds up and destroys everything in its vicinity. Because of this, paragravitic-tipped missiles or drones have become a staple of military doctrine. They are designed to get within range of the enemy ship, and then using their own paragravitic generator, attempt to set up a field scenario that the enemy's main computer can't solve for and thus force it to shut down or scale back paragravitic shields in an attempt to avoid resonance. During this time of course, the enemy ship is vulnerable to more traditional kinetic or energy weapons. Even if the gravitic drone isn't as successful, it might still open up a temporary hole in the enemy's defenses. Similarly, to the drones, paragravitic-pulse rounds have also been invented. Similar to flak-rounds and capable of being fired from an accelerator, they are designed to detonate near an enemy ship and convert all their stored energy into a single, localized, chaotic, paragravitic pulse. This, similarly to the drones, makes calculating a stable "solve" for all the paragravitic generators on the ship difficult, and could result in momentary loss of shielding. [Answer] I really like the way this subject is treated in Jack Campbell "The Lost Fleet" series, So to make it short, you do have force fields and missiles you can accelerate to relativistivistic speed (+ separate wormhole technology for changing star system), but essentially your ships are cruising at around .1 c and engage in fractions of a second since engagement envelopes are in thousands of kilometer at best. So you can see the enemy fleet from far enough away, goal becomes to have an angle of attack where more of your ships focus fire on a smaller segment of the enemy (to overload "paragravitic" shields), and to coordinate your troops through time and space (despite distance and speed creating measurable time differentials + time to bounce orders to more distant units). This makes strategy and story telling dominate over the grisly details, some weapons are kinetic, some are light based lasers, (paragravitic ?) force fields affect those, but they can overload as suggested in many answers. Problem is to aim at the opponent when we are all moving at decent fractions of speed of light (but not .95c, those are missiles) is that given the target distance you don't really know where the other precisely is. When engaging everyone is randomly shifting motors/acceeleration slightly to make it harder to predict where to fire. This is a really nice concept that comes to dominate the weapons technology. i.e. OK you shoot your missile at .95c, but what angle/how to target ? it won't be able to correct course at that velocity, so if the target is not fixed (e.g. sitting duck military base on a planet or moon) you wont hit it unless you throw a very large amount of crap to fill the volume/cone of space you expect me to be in. So, I'm suggesting essentially these paragravity generators are large, and adapted to space warfare, where we have the size of a ship (a few km) related to .1 c (30k klicks/second !) + average distance to target (in millions of km ?) so that targeting is the major issue. Anyone on a planet is dead however, just drop a rock it does not really even need a paragrav generator to make insane damage and targetting is easy. So we only can afford true shields on planets, maybe drawing from the magma core of the planet itself as energy source, they consume insane amounts of energy, but can stop incoming paragravitic weapons coming from space ships. In normal space warfare between ships, paragravity is enough to build smaller "force fields" that can be overloaded, with a clear attackers advantage. [Answer] ## Every action has an equal and opposite reaction Assuming access to massive amounts of energy - the gravity shield might be very effective but how good are those station-keeping thrusters? The force applied by a gravity generator still needs to be dissipated somehow. A ship accelerating a projectile will experience recoil via the gravity generator. A ship with a gravity shield stopping an inbound projectile of 1 kg travelling at 1m/s will receive 1 joule of kinetic energy from the projectile. In order to stop a projectile of 1kg travelling at 0.5c the ship will need to dissipate 10^17 joules of kinetic energy. Deflecting a projectile at an oblique angle will transfer less energy but will impart more rotation. Deflecting multiple dozens of incoming projectiles may make the ship uncontrollable. If the ship has no ability to station-keep then it will be lost - how much rotation can the hull withstand with no way to dissipate the energy? Just one 1kg projectile at 0.5c could cause the ship to spin itself apart. Another implication of this is that the gravity generator itself needs to be mounted in such a way that it can withstand the forces it will need to impart to various objects, but this could be hand-waved away with magical meta-materials. Here's how I imagine station-keeping could work in this universe: Object anchors A ship could use the gravity generator to stabilise the ship against a nearby object if one is available, but this might mean that a ship can only effectively maintain it's position under fire whilst within range of a massive object such as a planet. If a planet isn't available then the ship could stabilise itself against something which I will call a "kinetic gravity node" - a special kind of ship whose only job is to transmit kinetic energy, via it's gravity generator, to another node - and another, and another - until it reaches an "anchor node" which would be a node within range of a massive object. This would mean that for effective station-keeping in battle a chain of nodes would be required and these nodes would be a critical weakness in any fleet's ability to fight. An enemy would seek to disable the node chain and disabling it would grant a massive advantage. Or hey maybe you just cart a supermassive black hole around with you wherever you go. Just slip it in the glovebox. Gravity thrusters In addition to the nodes, ships could use gravity thrusters as a backup and carry a quantity of reaction mass which will allow them to station keep by expelling a stream of matter at ridiculously high speeds. In this case there is still the issue of how much they can carry and what happens when it runs out - however much fuel they could carry it will still have less available kinetic dissipation potential than the nodes, which have theoretically infinite dissipation potential. Shield defeating weapons Black holes I thought about whether or not a black hole fired directly at the shield would be able to penetrate it and I think the answer is probably not - from the shield's perspective it is just deflecting mass and as long as it can provide the energy necessary to deflect the mass then it doesn't matter what form the mass takes. Gravity grapples / ship catapults If you can't penetrate the grav shield then how about trying to accelerate the enemy ship into a nearby sun? This would only work if you can overcome the enemy station-keeping mechanism, which brings about a ridiculous concept: the gravity node tug-of-war. If you were able to lock onto an enemy ship and apply force via a gravity generator then the force could be transmitted all the way back to the anchor node. If the enemy node chain terminated at a planet and your node chain terminated at a much more massive object like a sun then you could move the enemy anchor object. Now the ship itself might not move because it's still transmitting the energy back through the chain and the anchor object is experiencing all of the effect, but half way across the sector the anchor planet might already be headed into a nearby gas giant. Unless you know what the enemy anchor object is you're effectively working blind - you have no way of knowing that your grapple is having any effect at all - you would only find out if the enemy grav chain stops working, and the targeted ship could just switch to thrusters and try to outmanoeuvre you anyway. Nonetheless it tickles me a bit thinking about throwing a random unseen planet around. Critical mass / singularity detonation There is a universal limit to the amount of energy which can be in one place at one time, beyond this limit you will get a black hole. This isn't the same as throwing a black hole at the enemy ship, what you would need to do is cause the enemy gravity generator, or one of their gravity generators, to exceed the energy limit for a schwarzschild radius matching the size of the gravity generator. If this happens then it doesn't matter how much energy is available to power the generator, it will immediately collapse into a subcritical black hole which will then immediately detonate, destroying whatever it is attached to. This assumes a ludicrously massive amount of available energy, but as some answers are already talking about accelerating large objects to sizeable fractions of c I figured I'd throw it in. You could single out an enemy ship with several grapples and then pump a short but massive burst of energy into it's shield - it would either detonate the ship or one of the enemy fleet's kinetic nodes, whichever one has the physically smallest grav generator. Either way it's a win. (Assuming some kind of safety mechanism which shuts down the generator before this happens this will still disable the enemy shield) Saturation All of the above assumes access to virtually unlimited power generation. If such massive amounts of energy are not in play then a simple saturation attack will defeat any shield. This is the same principle as real-world missile defence saturation. All you need to know is the maximum energy output of the enemy shield and to pump more than this amount of energy into the shield. With a gravity shield this just means throwing enough objects at the ship to overwhelm the shield - this can't be an arbitrarily large number (for arbitrarily large amounts of energy the above singularity detonation scenario is where I ended up). [Answer] As Nosajimki says it is incredibly wasteful to project a bubble like shield around an object as a defense. Point defense also doesn't work if your opponent is firing lasers or missiles at relativistic speed because you won't have time to detect the incoming attack and launch counter measures. With that in mind I think a plausible defense could be something like a shield or small projected area of para-gravity. So the easiest way to get past the para-gravity shield may be to go around it. I think the energy required to create artificial gravity would probably be equivalent to the mass required to generate a similar gravity field, so absolutely enormous. That gives another avenue for a would be attacker, tire them out. Or stealth using para-gravity to bend the light around you in just the right way to be invisible. [Answer] There is one way to defeat gravity. You can use anti-gravity. This is produced by exotic matter. It creates a negative curvature instead of a positive curvature given bu=y normal matter. Exotic matter (energy) is involved in the Casimir effect. but there the effect is electromagnetic in Nature. It has a negative curvature effect also though if you apply it in large amounts (like in the interior of a wormhole, to keep it open). Of course, the problem is how to get these amounts of dark energy-matter. How to make spacetime curve negatively? You have to create a vacuum with negative energy only (so without the effect of positive curvature caused by normal matter). This is very difficult but in principle possible. It's already happening with the universe at large. Because of this negative curvature (dark energy), the galaxies are accelerating away from each other (instead of accelerating towards each other. Thus in reality gravity (positive curvature) is already overcome. [Answer] If you really think about it, this shielding follows the same core principles of any sci-fi shield system. You just need to play with numbers a bit, but overall, you have multiple shield generators spread around the ship, each protecting certain sections. The fact that you use the same technology for attacking those shields simplifies things. In a situation where a Paragravitic system needs energy and staying cool to operate, and assuming the energy requirement is satisfied, we end up with thermals. As others already pointed out, depending on the details you go for, you would need to expend a similar amount of energy to deflect as you would need to launch the actual attack, and you can only output so much energy. Even if there was a drastic difference, let's say you only need 1/10 of the energy to protect yourself, your defenses can still be overwhelmed by (in our case) over 10x of that capacity. Problem is, your systems have to defend a whole ship, from every angle, while you can attack anywhere you want. So at this point, you have the capacity of a whole ship trying to overcome a single point. Think of an offensive version of shield rotations, where you'd rotate to bring up a more shielded area, while allowing the other shield batteries to recharge, but in your case, you'd rotate offensive generators, allowing them to cool down while applying constant pressure on the enemy generators. Even better, never fight fair odds. Devise tactics to coordinate fire, concentrate on the same area of the same ship from many of yours, until the generators fail. At that point, the ship will likely burn from within, or at least suffer even more internal damage, making it even more vulnerable. You can play with this some more, and perhaps coordinate defenses, so that one ship can help deflect projectiles from another. You would put the outcome of the battle in the hands of the party who fights smarter, and lessen the impact of the technology (instead of a stalemate, shift it into a situation of mutual negation). Perhaps try to develop stealth technology, you can't deflect what you don't know is coming. Or one last idea, use your generators to create anomalies, intense paragravitic fields that mess with the enemy's sensors, bend the light to mask the incoming projectile, so that the enemy tries to deflect something that isn't even there. [Answer] ## You can't "project" gravity far TL;DR if you can only generate gravity inside a machine, but not outside, you still get offensive capabilities, but defense is much harder. Make para-gravity a dipole like magnetism is. Magnetic fields lose strength in a distance-cubed manner once you are outside of the generator. If you can't cause a significant gravitational field to extend around some sort of coil, then you will have a difficult time slowing down incoming fire. However, you can still use it to attack because your "para-gravity" coil would be contained inside the barrel of your weapon. Also, every para-gravitic field would have at least 2 weak points in it at the poles, which would make for good targets. [Answer] 1)With Paragravity used to it's fullest potential, you could have weapons, say missiles, equipped with onboard generators that can counteract the affecting field with it's own opposite effecting field. These would necessarily be large, but maneuverable at less than relativistic speeds. 2)You could implement superdense (neutron star core)kinetic rounds, with so much mass per cubic centimeter that the Paragravitic shielding would begin to struggle with more than one/a few projectiles. Conversely, the weaponization of extremely large objects, asteroids or small moons could overwhelm the shield. 3)Following the thinking of an earlier suggestion, you could equip inbound weapons with a small "mass neutralizer" that temporarily negates the mass, making it effectively zero, therefore gravity would have little or no effect. 4)A dimensional phase shifter or "skip field generator" , that could essentially make the weapon exist outside of our spacetime , arriving too late for the field to act/ inside it's null zone/ inside the target ship. 5)A particle beam weapon that consists of particles unaffected/ barely affected by gravity, such as a super concentrated neutrino beam. Neutrinos are so small that it barely interacts with real matter. Super-Concentrating the beam would ensure that more and more of the particles DO collide with matter causing various effects such as cooking organic matter, electrical power faults, hull deterioration, damaging sensitive AI components, heat accumulation overpowering shunts, sinks, or sumps, other possible mental, physical or psychological issues with the crew(rapid aging, radiation sickness, immune disorders, elevated body temperatures above high fever causing hallucinations and so many other factors possible here, just think entropy on fast forward. 6)Some lower tech methods possible: a)Wide array solar concentrators heating up space Around the target, making heat dissipation impossible as the "outside space" temperature exceeds that of the ships' sinks, sumps and pumps. b)Many conventional nukes going off at once or at regular intervals also preventing heat dissipation. c)Smaller, faster ships, conducting constant random harrying attacks, effectively "laying siege" to the vessel preventing resupply, materials/energy gathering, starving the ship/crew over long periods of time. d)The old standbys, weak link exploitation: crew manipulation/extortion by the enemy who capture their loved ones and will kill them , unless they betray the ship by shutting down the shields, or the defecting/ sleeper agent crewmember who sabotages the shields. e)Or the field generators fail for some mundane reason, blown power coupler/faulty relay/shut down for some period of time due to diagnostics trigger by ship damage, or normal system operation/ accident/ equipment failure. Disclaimer: "I am a senile old man and these are the ideas that ocurred to me while waiting at the pharmacy, therefore I am not responsible for any unintended plagiarism or other mistake in any way, being entirely educated by the system, the internet and so on, any similarity between my thoughts and reality actual or virtual cannot be avoided as we all get our information from similar sources. That being said, I read the other comments here and attempted to apply as much of my own personal innovation and originality as I could. I make no claims as to being completely original as that is completely impossible. In other words:"I did the best I could." I hope this was helpful to someone. I do not require any thanks, nor comment, constructive or critical. Cheers all. [Answer] Three “silver bullets” that would effectively deter paragravity weapons and compromise such shields. 1. Spacetime wave echoes, 2. Using blackholes as land mines, and 3. Gravity wave interference. --- --- 1) Thanks to the recent LIGO experiments, we’re fairly sure that the “force of gravity” travels via waves (and possibly particles). These waves would act like a submarine’s sonar echoes - giving away its location before any shields or weapons were even ready to deploy. > > A paragravity weapon would have to distort spacetime first and then > the object or missiles would follow that spacetime curve as a cause > and effect. > > > This sequence of events gives everyone in the vicinity a “spacetime warning”; like putting your ears to the railroad. The time delay between spacetime warping and objects moving would at the very least cause the famous “long power up” weakness whether used for shields or weapons. A clever enemy could use this warning time to escape, speed up towards their target, fire, or do anything within that time (understanding that it may be less than a second but still somewhat useful). Also stealth becomes super tough. 2) Kurzgesagt taught me that blackholes can be moved like chairs in your living room, given enough energy. Also, it’s possible that there are all sizes of blackholes from marble-sized to, well, gargantuan. Seeing as these things are the ULTIMATE gravity warper in the universe: I assume they could effectively be used against a shield that depends on gravity. For example, it would be like using a medieval metal shield in an MRI room. The magnets from the MRI would just rip that shield from you like it was grade school lunch money. So I assume with that kind of power nearby, or even moving around like some super advanced battering ram thing, a black hole on a leash could effectively nullify those defences. Depending on how sensitive the paragravity tools are to distortions it might even fry them permanently. > > It could also absorb attacks since nothing, not even light, can escape > a black hole. > > > 3) Gravity wave interference. Basically what dragongeek eloquently stated above. Annihilate incoming waves be they gravity or sound. A clever opponent could even use #2 above to create a Sydney Opera House-type defence around their fleet or home world to eliminate all resonance and gravity waves that they don’t specifically want. Much like an opera house can be designed to specifically control sound waves. > > You can annihilate gravity waves using the same principle as noise > cancelling headphones. > > > That’s all, me thinks. ]
[Question] [ I'm writing a story about a modern age HEMA medievalist who time travels to the Viking age. Is it possible to make a crossbow with similar performance to modern age [crossbows](https://www.tenpointcrossbows.com/product/vapor-rs470/) without using modern materials such a aluminum, nylon and carbon fibers? I'm expecting a result to be something with wooden frame, horn and sinew limbs, and steel [cams & wheels](https://simplearchery.com/how-does-a-compound-bow-work-the-simple-explanation/). Cocking mechanism could be omitted if unfeasible. I'm assuming that all technologies are available in that time from across the whole of Eurasia (metallurgy, bow-making) would be accessible (and can be traded for). I'm looking for something with similar performance to the modern crossbow which has 470 FPS / 182 FP (246 Joules) of kinetic energy. For comparison : * Medieval longbow (95 lbs draw weight); 45 Joules * Medieval crossbow (450 lbs draw weight); 53 Joules * .22 LR; 168 Joules * 9 mm; 467 Joules * .308; 3,217 Joules Source [Tod's Workshop](https://youtu.be/TdB470lo6nM?t=1077) [Answer] ## Is it possible? I think it should be possible. The force for the projectile is still held in the bow for the most part, right? The cam and wheels just allow for a different orientation for the device. The idea of a cam [predates the viking age significantly](https://en.wikipedia.org/wiki/Cam#History). Miniaturizing it might be a challenge, but let's not discount the skills of the blacksmiths of the age, if the goal is described to them I think they could pull it off. Your guy isn't a HEMA professional, right? I don't think there are many of those. Maybe his day job is mechanical engineering or machining. Based on [this sales pitch](https://www.tenpointcrossbows.com/blog/top-5-reasons-to-shoot-a-reverse-draw-crossbow/), the main benefits are * better weight distribution * slightly longer powerstroke, for size * a stabler and quieter shot So, this isn't going to produce some crazy armor decimating device. Because the force is still held in the bow, and your guy probably isn't going to bring some massive material science advantage with him, this will just give his team access to bows that they could have designed previously, but they would have been slightly large and awkward to aim. ## Why didn't it already exist? On a per capita basis medieval people spent way more time thinking about killing each other than we do (citation hopefully not needed), so these question always come with the built in: why didn't they invent your guy's new idea for a weapon? I think it is plausible in this case, though. The main benefits are easier aiming for precise shots. The crossbows they had were mechanically much simpler, which is a huge production and maintenance advantage. For war, we expect the soldiers to mostly be firing in formation anyway, so precise shot accuracy for targeting individuals is not a huge priority. For hunting, bows do just fine. Your market is mostly peasants (nobles too, but they are hunting for sport mostly -- they aren't interested in totally optimizing the productivity of their hunting experience, they won't revolutionize bow design to support a hobby). Miniaturized cams will probably require a skilled blacksmith, so you aren't swimming in the things. In addition, technology development is largely evolutionary in most cases. I don't think traditional crossbows + cams are enough of an advantage to be mass produced. The weight distribution benefit of changing the orientation of the bow isn't immediately obvious, and the orientation change is a pretty big leap. So, it seems plausible that nobody thought to do it until machinists started seeing the prerequisits everywhere in their day-to-day lives, and one of them happened to be a hunter. You at least have plausible deniability, here. ## What good is it? I suspect that you'll need to at least get the best blacksmith in a large town/small city on board with this plan. You aren't mass producing these things in every little village across the land. Plus, they are more mechanically complicated. So, I don't think you are arming your whole army with these things. These will be your medieval Designated Marksman's Rifle. Plus, they are all hand crafted by blacksmith unfamiliar with the tech so there will be lots of quality variations, especially at first. Presumably, your guy is also bringing some modern tactics. Perhaps you can arm a small squad of troops with the bows that randomly ended up highest quality, and use them to sneak up on the enemy camp beforehand and take out the leadership. Your superior range, quietness, and pinpoint accuracy will come in handy here. (also, you can probably copy some other modern features, like the bipod). You can probably also embed a couple of guys with the special bow into your crossbow units to take aimed shots at high value targets during battles. A nice perk of this is that the device isn't so obviously weird that the guy will stick out from afar, so to your enemies it will just feel like a weird coincidence that the guy carrying the signal flag seems to always get shot first thing every battle. [Answer] While the parts themselves can be replicated using medieval tech they have nothing to do with a bow's maximum velocity. ## Where maximum velocity comes from: Your materials have various properties depending on if they are in the belly or backing of the bow that determine it's snap. More snap means a higher base acceleration. Wooden bows tend to have a lower snap than something like fiberglass; so, medieval archers compensated for this with arm length. This works up to a certain scale because the snap is compounded across the length of the arm. Arm length compounded with materials determines the ideal maximum velocity. What about draw weight and length? These are important factors behind a bow's power but not speed. A bow with a lower draw weight will receive more relative resistance from the weight of your arrow meaning a bow with a higher draw weight can more effectively fire a heavy arrow, and will shoot a little bit faster because it can better overcome the arrow's inertia, but still caps out based on the material limitations. It's like this: a strong man can not throw tennis ball much faster or farther than a weaker man with similar technique, but a strong man can throw a bowling ball much faster and farther because he can overcome the weight better. Medieval war arrows were on average 2-3 times heavier than hunting arrows so they could better penetrate armor which is why draw weight was so important on a warbow. Draw-length is similar to draw weight in that it mostly contributes to doing a better job of reaching the maximum velocity that your snap allows. A greater draw length gives you more time to accelerate the arrow allowing you to reach closer to your ideal maximum velocity before it leaves the bow, but again, does nothing to increase the ideal maximum velocity. What does a compound design do? A compound design uses pulleys to convert poundage into draw length. So, if you have a crossbow arm with a 200lb 18" draw, and you compound it by a factor of 2 (that is a single wrap on each cam), then you reduce your draw weight to 100lb and extend the stroke to 36". Although this gives you the same specs on paper as a standard warbow, your bow tips don't have to move as far as they would if it was a warbow giving you a higher apparent snap. So your arrow is shot at a higher speed and lower power using the same materials. The issue when it comes to making compound crossbows out of traditional materials like wood is that wood performs much better when you thin it out more. The thicker you make your bow arm, the greater the backing tension and belly compression becomes as you apply a given amount of draw weight. Furthermore, crossbows become MUCH more cumbersome than warbows if made as long as a warbow. Warbows and war crossbows are designed to be used in battle formations meaning that you can make vertically aligned bows much longer than horizontal ones without getting in the way of the guy next to you. For this reason, war crossbows were typically no wider than 25" whereas a warbow was typically 72". All that extra length gives you more material to store potential energy before your wood ruptures. So, while you could make a compound wooden crossbow, you could not effectively make it at a scale that would be as strong as a warbow. So where does this leave you? Since the viking age mostly predates spring steel, fiberglass, etc, the fastest bows you can really achieve will probably be just over 200 FPS using either a bamboo and hardwood composite or a horn and sinew composite. Neither of these materials would particularly benefit from the compound bow or reverse draw crossbow design. Compound bows need to take advantage of modern materials that can store much more potential energy than traditional materials. Traditional materials can already be pushed to thier limits without a mechanical advantage, but steel and fiberglass when coupled with pulleys can get a better effective snap than wood without having to sacrifice too much draw weight or flexibility. The reason for reverse draw crossbows is because those same materials have more snap in the compresion state than the tension state. In contrast, most traditional materials get more of thier driving force from the tension of the backing material than the compression of the belly material; so, inverting them to be compression dominate would make them worse. If you want a better projectile speed/range, the Roman manuballista and scorpions could hit speeds much closer to a modern crossbow using coiled sinew cords. These designs don't work on the principle of tensing thier arms at all; so, reverse draw mechanisms would not apply, but you could in theory add a compound bow mechanism to one to multiply it's speed in exchange for a lighter projectile. Vikings could almost definitely make them if they tried, but they were really heavy weapons compared to bows or crossbows; so, the trade-off is only worth it in certain cases. If you fast forward to the later medieval era though, you will see spring steel crossbows start coming into play. These were limited to very short draw lengths because the arms could not bend much, but they had tons of snap and draw weight. If you were to add compound or reverse draw mechanisms to these, then you would be able to achieve something much closer to a modern crossbow without having to make something too heavy. That said, spring steel was never an easy thing to make, even in the late medieval period, it took a highly experienced smith to properly temper the steel without the use of modern high temperature thermometers. [Answer] > > Is it possible to make crossbow with similar performance like the modern age crossbows without using modern materials such a aluminum, nylon & carbon fibers? > > > I'm expecting result with something with wooden frame, horn & sinew limbs, and steel cams & wheels. > > > Obviously no, I would say else it would have been made already in those times, since those very materials you cite were used. Don't forget that weapon making and improving has always been a very prized profession, and improving an existing weapons would have granted a good reward. If you want modern performance, you need to use modern materials. [Answer] It might be possible, but you are not going to get any better performance out of it than crossbows at the time, likely far worse. Steel cams are heavy and likely beyond viking technology, bone or wood ones will not hold up to the stress, so you are looking at copper or bronze, which is again heavy, stealing a lot of energy from the bow and subjecting the arms to very high stresses. You also don't have modern machining to get smooth bearings so you loose a lot of energy and get a lot of wear and tear. Worse they have no way to produce a strong enough frame, you can't use wood becasue the frame is withstanding a lot of tension, which means everything frame,limbs, and cams needs to be made of metal, which means more losses of energy and you will not be lifting and using this device even if you could make it. All together energy you lose in material mass and bearings means the cams don't give you any advantage. Now keep in mind 2000+lb medieval crossbows exist, although they are also likely beyond what the viking could produce. Which would work like the cranequin below. Which were also pushing the limits of what medieval steel and wood could withstand. [![enter image description here](https://i.stack.imgur.com/XIiUp.png)](https://i.stack.imgur.com/XIiUp.png) [Answer] I'll offer a bit of a frame change. A compound bow, using a system of cams or other devices, is not intrinsically more powerful than an ordinary bow. English and Welsh longbowmen used warbows with draw weights of between 100 and 120lbs (enough to cause distinctive warping and other changes in their skeletons), while by the 1400's, steel crossbows with draw weights of 1200lbs were in service, requiring the use of a winch spanning mechanism to draw. Only hobbyists make things like that today, few commercial hunting bows approach anything like that amount of draw weight. [![enter image description here](https://i.stack.imgur.com/XrkCH.jpg)](https://i.stack.imgur.com/XrkCH.jpg) A lighter crossbow drawn by hooking the string to a belt and using the muscular strength of the legs The purpose of the cam mechanism in a compound bow is to "let off" the maximum draw weight. A 75lb hunting bow will require a draw of 75lbs, but once past the point where the camming mechanism kicks in, the actual weight the hunter has to apply to keep the bow drawn is much less. This makes aiming and releasing much easier (and since few people have been training with bows since boyhood, the skill to rapidly draw, aim and shoot a high draw weight bow is not very common). Since a war crossbow is already mechanically cranked and then "locked" into full draw by the trigger mechanism, and the archer is going to loose rather quickly, there is little benefit for having a compound bow mechanism. Archers are not waiting in a tree rest or blind waiting for an animal to appear, rather they are in ranks between men at arms or pike squares drawing and loosing as quickly as possible or practical at massed targets before them. So while it may be possible for Viking era bowyers to apply laminations to wood, or experiment with steel to make more powerful crossbows, eventually the limits of that era's material science is going to be reached. Bows of any era were generally as powerful as possible given the materials at hand and the archers who could use them. [Answer] Your time traveler can always resort to the [repeating crossbow](https://en.wikipedia.org/wiki/Repeating_crossbow). It's not as effective as a modern, but for that age, it is effective, easy to build with the materials at hand, and easy to use. [![enter image description here](https://i.stack.imgur.com/EN3mU.png)](https://i.stack.imgur.com/EN3mU.png) [Answer] Seems to be doable though we don't know how expensive or cumbersome this device would be. Cams and draw mechanism are out of reach of Viking technology, so let take [Bulldog 440](https://www.excaliburcrossbow.com/crossbows/matrix-bulldog-440/) as a target. [![bulldog crossbow](https://i.stack.imgur.com/FfoiD.jpg)](https://i.stack.imgur.com/FfoiD.jpg) I assume that wooden frame is possible since there are 1200# crossbows made of wood, Vikings could definitely make something like modern frame though heavier. 420# draw weight is possible to be drawn with stirrup & doubler belt. 8:54 <https://youtu.be/2IdfmaC_t-Q> Trigger would be primitive but usable. There was traditional recurve bow with 200# draw weight so I assume 300# limbs are plausible. Turning the limbs around will increase your power stroke, which will increase your efficiency, however craftmanship need to be top notch to avoid 300# limbs cracking in front of your nose. Consult experienced bowyer for opinion. I think I read somewhere that excalibur tried that but hunters find them uncomfortable. The last problem is that traditional limbs would be very heavy and inefficient compared to modern ones. This is something that you can't surmount without modern materials. Your crossbow would be slower & less efficient than a modern one. All in all you might make the best crossbow in that period but it would be far from a modern one. With twice the draw weight of a longbow & 66% of its power stroke it might be enough to change history toward infantry if you could mass produce it. ]
[Question] [ This question already has answers here: [Plausibility of Ice Eaters in the Arctic](/questions/152608/plausibility-of-ice-eaters-in-the-arctic) (11 answers) Closed 4 years ago. At age 9, I drew an alien which I described as "eating ice". Occasionally I've wondered if that's possible. Carbon-based Earth life only uses water as a solvent and consumes carbon compounds for energy. Is an alien biochemistry possible which consumes water for energy? EDIT: And not carbon compounds (so no, photosynthesis doesn't count). [Answer] Plants consume water for their energy metabolism. Water is more than a solvent for a plant. It is one of the 2 raw materials they use to make sugar. The formula for photosynthesis is CO2+H2O+ light -> CHO (sugar) + O2. Plants do chemistry on water molecules, splitting the H2 from the O to trap the incoming energy from light. Without water chemistry there is no photosynthesis. Plants (and us) then reverse that and combine CHO with O2 and release the energy. If you wanted more straightforward water-only energy metabolism, you could use sunlight (or some other energy source) to electrolyze the water to H2 and O2 then have your animal recombine those back to H2O in such a way as to recapture the released energy as ATP --- If photosynthesis is considered cheating (!) and you just want to use the energy in pure water, you could have your creature consume hot water. Water is sometimes available at temperatures considerably above ambient - geothermally heated or heated by the sun. You could have a creature which drank hot water and used the energy difference to effect a conformational change in proteins. When the proteins relaxed back to their normal low energy state, they could turn a molecular wheel and generate ATP. [Answer] It is extremely unlikely that there would be such a biochemistry. Water is very stable molecule because it's the "ash" of burning hydrogen, so there isn't much energy left in the molecule that can be liberated. Now, you can oxidize water as fuel, but to do so you need an extreme superoxidizer, such as chlorine trifluoride\. But when you get into chemicals like these, they are basically so reactive that there is no stable biochemistry that could form around them. \: Famously described to spontaneously ignite on contact with any known fuel without measurable ignition delay, and also able to burn other extremely incombustible things like sand and asbestos, not to mention test engineers. [Answer] > > Is an alien biochemistry possible which consumes water for energy? > > > In theory, you could have a biochemistry that used fluorine in the way that we use oxygen. Fluorine reacts with water to produce hydrofluoric acid, oxygen and some energy, so such a metabolism could "eat" water. Thing is though, you'd get a lot more energy eating pretty much anything else... have a look at videos of fluorine gas reacting with various other materials (spoiler alert, it involves a lot of things catching fire). You'd also need to find some mechanism for producing fluorine... the damn stuff is so much more reactive than oxygen that even if you did have a fluorine-producing photosynthesiser you'd have a hard job finding an environment where it would persist in an atmosphere for long, and if it did it would rapidly react with any nearby water. Still, the possibility of [fluorine-based life](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4206852/) has been considered, and doesn't appear to be totally implausible. It probably wouldn't "eat" water, though. [Answer] There are two concerns here: Energy and Materials. Energy Is covered pretty well by @Willk. I just want to reaffirm that the bonds in water could be used to both break and make the bonds of ATP depending on the enzymes at play. Materials However, I think the bigger issue is materials. The average human is made of Carbon (20 kg), Ammonia (4 L), Lime (1.5 kg), Phosphorous (800 g), Salt (250 g), Saltpeter (100 g), Sulfur (80 g), Fluorine (7.5 g), Iron (5 g), Silicon (3 g) and fifteen traces of other elements. (I'll find the citation later). The point is that a person is made of those things because they eat those things. What are your aliens made of? Even plants absorb sulfur and phosphorous from the ground and carbon from the air to build themselves. If you want your species to only eat water, could I suggest making it silicon-based and drinking [lava](http://volcano.oregonstate.edu/what-lava-made) for materials? This would provide all the base materials for an organism. Such a world, with solid ice and liquid rock side-by-side would be an interesting place. [Answer] Possible, and the other answers miss how ice can "contain" energy. As water freezes, dissolved salts predominantly remain in the liquid phase. If you melt this ice, the resulting water will be relatively pure. Now it turns out that for entropy reasons, you can extract energy from mixing pure water and salty water. Hence, we may have an animal that lives in a cold, salty lake. It drinks salt water and eats ice, extracting the energy released from mixing it. The reason this can work is because the ice is formed at night when it's colder, and the animal sits in the sun during the day to melt that ice. Hence, the animal effectively lives off the energy from the temperature difference between day and night. The key here is that it's not just the ice that contains the energy, drinking salt water is also necessary. [Answer] The alien would have to have a very different chemistry to ours. And live in a very different environment. Quite radically different. There are some chemicals that can react with water to release energy. It is just barely possible that such a chemical basis could support an organism. Under the right circumstances, for example, various metals will take the oxygen out of an H2O molecule and release heat. It would have to be a very different chemistry to ours. And they would need to obtain several other chemicals besides water to sustain themselves. So to build a little more of an ecology. Imagine a plant that absorbs sunlight and converts something like aluminum oxide and some hydride compound into pure aluminum and water. It might then release the water, possibly as ice crystals if it is cold, and use the aluminum to build its structure. The ice-eater could then come along and use the plant as one part of its food, and the ice as another part. Conceivably such an organism would be radically susceptible to various chemicals we take for granted. It might spontaneously combust in the presence of free oxygen, for example. (Hmmm... SE's dictionary does not know the word combust. Hmmm...) Now there is just a huge amount of chemistry that would have to be worked out to make that work. It would involve a lot of things like acids and catalysts and ways to store such things. So, whether it is in fact possible, or even vaguely likely, I certainly can't say. On the other hand, carbon chemistry also has a huge amount of complicated and subtle reactions that are required for the kind of life we know. If I was required to sit down and work out if carbon-based organic chemistry was possible, given I was only familiar with the conditions in Saturn's rings for example, that would be a daunting task. [Answer] Unlikely. Water does react chemically with many compounds. Alkaline metals, some halogens and certain compounds are the exceptions. Of those, only fluorine can make a plausible atmosphere that a creature can breathe to oxidize water. But free water would not be able to coexist with fluorine atmosphere over long periods of time. As @puppetsock pointed out, this whole ecosystem would be very problematic. However, water can produce energy without having a proper chemical reaction. Just hydrating and dissolving many compounds can yield a noticeable amount of heat. So I can imagine that the world this creature lives in is a desert. The creature would eat some dry salts and then drink water. Salts would dissolve in the stomach, producing heat, which can be used as a source of energy. However, this restricts energy generation to the stomach. Cell-level metabolism would be difficult to imagine. In humans and animals, nutrients are transported to individual cells by blood, and energy-producing process occurs there, inside the cell. If we want similar process here, then this hypothetical creature would need to have a transport mechanism which can move dry salts from the stomach. [Answer] This creature could "eat water", although water would not be what provided its energy. It could break down the water into hydrogen (used as a fuel), and oxygen (used as an oxidizer). It could have a digestive system more like the fuel consuming machines we have. it separates the hydrogen from the oxygen via electrolysis, with the electricity coming from solar panel-like structures. ]
[Question] [ The Artarkan Star Empire is a loose confederacy of stellar warlords, pirates, slavers, and other groups lying on the edge of known space. While most of these groups hail from one common culture (Artarkan) most operate as independent "clans". The Empire itself was founded by Ar'xhir the Conqueror who unified the warring clans by brute force and political cunning. But how could Ar'axhir's descendants maintain his Empire? More importantly: How could future emperors keep the clans loyal to the crown with minimal rebellions, but also retaining autonomy for "loyal" clans? Notes: * Centralization is not an option due to the probable outcome of the clans rising up in rebellion against the loss of their "Rights". * Economically and technologically the Empire is maintained by a raider culture that participates in slave raids and looting of neighboring systems. Rarely does an ambitious warlord conquer, say, a moon or even a planet. * Religiously the Artarkans believe that only through raiding (to obtain offerings) and conquest that the Gods will be satisfied and will prevent the destruction of the universe (think Aztec or Assyrians). * The Empire would be vaguely feudal but many of the "realms" are carved out by the Clans themselves, not assigned by the Imperial Clan. * Fighting and warring between the Clans is common but regulated with the Imperial Clan stepping in when the fighting gets out of hand. [Answer] There is a problem with raiders. They don't build. Some historians used the label [Gunpowder Empire](https://en.wikipedia.org/wiki/Gunpowder_empires#The_Hodgson-McNeill_concept) for an empire where only the central government had the means to produce [siege guns](https://en.wikipedia.org/wiki/Dardanelles_Gun) and the vast amounts of ammunition they required. (This catchphrase is a simplification, of course.) Assume that only the ruling dynasty controls shipyards and factories to build proper warships. Again historically, the ability to produce [armor plate](https://en.wikipedia.org/wiki/Harvey_armor) and [big guns](https://en.wikipedia.org/wiki/Royal_Arsenal#Mechanical_and_managerial_developments) was limited to a few arsenals and factories. Find something similar in your technobabble, from force field generators to high-powered particle beams to electromag starfighter launch catapults, that comes only from the "Imperial Arsenals." Other yards and contractors might be able to do routine maintenance, or build civilian starships and smaller warships, but not these specialized military components. Of course the lesser clans realize what is going on, and many resent it. But building an "Imperial-level Arsenal" for the clan requires enormous up-front investments, and years of vulnerability while the capital is sunk and the yard is not yet producing. If the Emperor cuts warship delivery during this period, the clan is toast -- the Emperor does not even have to sully his hands, other clans will handle that. [Answer] Give them a larger threat I have two examples of this being used with pirates in culture and history. The first one you are probably familiar with: Pirates of the Carribbean 3 - the pirates of the world basically elect a unified fleet commander in response to the threat of British vessels threatening to ruin all their livelihoods. The body that enforces they follow the rules - Captain Teague - is not a member of any of the contributing pirate squadrons and thus has no conflict of interest. My second example is a bit more accurate and follows Ching Shih - who commanded the largest pirate force in recorded history. Ching Shih's personal rise to power is because of various favors and political maneuvering, but the reason her fleet stayed together is to combat external forces - such as the Chinese Government, the East India Company, and European fleets- and internal forces such as other pirate gangs and raider groups. This didn't just mean they had the biggest stick, but they also distributed the risk. A squadron with failed and damaged vessels would be supplemented by spoils from more successful squadrons. [Answer] > > Religiously the Artarkans believe that only through raiding (to obtain offerings) and conquest that the Gods will be satisfied and will prevent the destruction of the universe (think Aztec or Assyrians) > > > You got your answer right here. Only do they worship a god-emperor and not gods. As it happens Ar'xhir the Conqueror is, in fact, the highest of the gods who descended to the mortal plane to save mankind (those who follow him). Why should the clans follow his heir? Because a god needs a vessel to exist on the mortal plane and when his current vessel decays he will enter the body of his heir. At least this is what he tells everyone and if you question it his devote followers will do all the nasty things to you religious fanatics are known for. These fanatics will do the same thing to you if you fail to bring offerings (taxes) and do anything that the dear god-king dislikes. The idea of god-kings and charismatic and mighty leaders declaring to be sent by heaven is hardly a new concept. See the mandate of heaven in China, Charles XII of Sweden, the Pharaos, any modern sect (Scientology, Mormons, ...), the pope and Roman emperors, the Chalif,... . I would recommend watching documentation on how sects control their members to learn more. The issue with handling a sect is that ideology and religion tend to be flimsy things if you got little direct control over the people and they are very autonomous. They as the history of the Abrahamic faiths shows will develop their own interpretations and religions based on the original to benefit themselves. This is of cause an issue, but we are worldbuilding sci-fi here. So let's bring in the star of the show: ## [Ophiocordyceps unilateralis](https://en.wikipedia.org/wiki/Ophiocordyceps_unilateralis) the [mindcontroll fungi](https://www.livescience.com/47751-zombie-fungus-picky-about-ant-brains.html) > > Fungal cells in the ant's head release chemicals that hijack the insect's central nervous system. The fungus forces the ant to climb up vegetation and clamp down onto a leaf or twig before killing its hapless drone. > > > Let's assume the imperial clan or someone they hired genetically and biochemically modified the fungi so it pushes all the right buttons in someone's brain to trigger religious awe and make someone susceptible to propaganda. This would be the light version, the heavy one could include anything from psychological mind-control triggers to visions and dreams detailing the great deeds of their god-king. Sadly I can't claim credit for this idea, I only picked it up from Alistair Reynolds. He first used it in [Chasm City](https://en.wikipedia.org/wiki/Chasm_City) and later for the sect Quaiche sets up on Hela in [Absolution Gap](https://en.wikipedia.org/wiki/Absolution_Gap). Ar'xhir the Conqueror would of cause have to infect the chieftains of the other raider factions with the virus and indoctrinate them. He could have done this one by one or all at once during a great feast (maybe a victory celebration that lasted a week). If the fungi are easily transmittable than only a few people from each clan must be infected to infect the whole clan. If Ar'xhir the Conqueror himself is infected he might actually believe that he is a living god or his vessel and suppresses the memory of his great scheme. So, in summary, the clans will be very autonomous but will pay taxes, spread the good word and be very willing to appear if the emperor summons them (who would refuse the honor of being in the presence of his god, after all). This is somewhat of a space-mongol-scientology-borg thing and it will be really effective, logical and scary. PS: One could say all you need to start and maintain a religion is a fun-guy/fungi like the god-emperor. I'll see myself out... [Answer] What you are describing very closely resembles feudal Europe. Lack of reliable communication and transit meant that local lords were very autonomous in their day to day activities allowing them a lot of freedom go out raiding and fighting among themselves, but everyone was sworn to a lord who was sworn to a higher lord who after so many layers was sworn to a king which the most of the nobility rarely ever heard from but obeyed without question. The king only ruled a very small part of the country directly, but indirectly everyone was sworn to him through the feudal chain of command making him too powerful to challenge. Feudalism works best when each lord only has the ability to effectively control lands within a certain proximity of his home, these divisions of land were typically called counties or parishes. In medieval Europe, poor roads and lack of good communications systems typically limited a county to a town and the surrounding farms and wilderness. In your space civilization, it could be that interstellar travel and communication is hard or time consuming enough that planets or solar systems only make sense to be locally governed. Either way, because lands beyond a certain point take too long to exchange communications with, it's very hard for a lord to govern what happens too far away. Since each territory is surrounded by other territories, no one county can safely stand on their own so they will need to form alliances. The lords of each county will tend to flock to the most powerful other county in their region for protection by swearing loyalty in exchange for that protection. The more loyalty a count can garner, the more absolute his power over the region becomes until eventually he established a larger division of power where everyone who lives in his shadow is forced to swear loyalty or be conquered by the combined force of this alliance. These larger areas are typically called duchies. As these duchies start to form you will start to see a lot of adjacent dukes start going to war over disputes about who should have the vassalship of certain border counties; so, they start to find themselves in the same condition as before of being surrounded by too many enemies. These dukes then form even larger alliances where a powerful duke begins amassing the loyalty of other dukes. Depending on how large your feudal kingdom is, this process may repeat itself many times and create a complex system of alliances resulting marquis, earls, viscounts, barons, etc. Regardless of how complex the system gets there is always going to be one guy at the top of this pyramid scheme. This is king Ar'axhir. On its own, Artarkan may not be the strongest planet in the kingdom, but it is at the center of this complex system of loyalties, and that makes it the strongest world. Limited fighting and warring between the clans is both tolerated and to be expected by the Artarkan, because they understand that this is a natural part of lords vying for greater positions in the upper courts. Intervening in these conflicts would often mean dispatching forces over very long distances; so, the king and higher lords generally only involve themselves in a conflict when it escalates enough to threaten their own power; otherwise, these "quarrels" are just seen local matters for the lesser lords to deal with. Ultimately, this means that the ruler of the empire does not own the hundreds of other worlds in his kingdom, and he must be careful to tread lightly when it comes to telling them what to do, but as long as he maintains these loyalties well through close relationships with the uppermost lords who are sworn to him, he can muster enough of the kingdom's strength whenever needed to exorcise his supremacy and re-establish order whenever things get out of hand. This means that local lords seeking to gain power won't risk doing so by raising large armadas and trampling dozens of worlds under foot, even if they have the power to do so. Instead, they rely on things like isolated raids and state sponsored piracy, to undercut their rivals' power and obfuscate culpability. [Answer] The Emperor has a Big Red Button for each clan. Way back, when Ar'xhir the Conqueror brought the clans under his sway and had them swear fealty, they were also made subject to a system, process, or scheme by which Ar'xhir gained the power to irresistibly destroy them and all their descendants. * Perhaps Ar'xhir infected them with a genetic trait that makes them dependent on a substance only the Empire can provide. * Perhaps they were compelled to use technology with a software backdoor that allows detonation of all their ships' drives. * Perhaps they were compelled to reveal the coordinates of their home planets/bases, and are regularly checked and tracked, if simply knowing that information is sufficient to ensure destruction. In any case, the descendants of Ar'xhir may not have overwhelming military power compared to the other clans, but they have them by the throat if any of them tried to rebel openly. [Answer] Might makes right Like all empires do. The leaders have power over others, be it firepower, numerical superiority, wealth, information, influence, resources, a super weapon or pure charisma. Perhaps the leaders have control of the only starship building facilities. Maybe the only fuel refinery capable of producing starship fuel. A vast network of spies so the factions are played off against each other leaving the leaders as the strongest. Perhaps the offspring of the different faction leaders are expected to serve the king before they can inherit their house. The factions send them to act as spies and the king accepts them so they double as hostages. Whatever the reason, the leaders have power over the others. The others might do things on the sly to try and shift power their way but know they cannot challenge the leader directly and win. [Answer] Raiders by themsevles tend to be small and squashable (by military state standards) so give them the opportunity to not get squashed but continue their raiding under certain restrictions. This is have pirates of the new world operated - a British pirate would be given a letter of marque saying they wer enot really pirates, but "independant agents of the British crown" as as long as they didn't attack British ports, only Spanish ones, all was considered fine. Once you have that level of integration into the ruling establishment, some pirates, as they got older, would seek riches within the empire rather than the dangerous and not-so-comfortable life outside it. Piracy is a young man's game after all, sitting in an office with a nubile secretay and drinks cabinet telling the yougn men what to do is exactly what an old pirate will wish for - so will not ruin his chances to get it in the future. If you don't have an external enemy to let the pirates loose on, then the next best thing is to ensure they don't do too much damage, let them loose making sure they follow the rules of not disrupting trade, not attacking certain designated planets and only pillaging to a designated extent. if any don't, then let the other loose on the naugfhty pirates, they'll self-regulate! [Answer] 1) The ruling clan is the Bank. Like in Game of Thrones. If you step out of line, they will call in loans and encourage other factions to take you out (in return for economic advantages). Further, raiders grab lots of stuff, which means they may acquire stuff that's useful to others, but not themselves. The go-to "fence" at which to sell your unwanted items is the ruling Clan (and their bank). Only they can really afford to buy large quantities of hard-to-get-rid-of things for gold or cash. The other Clans would need to basically barter -- if both sides of the deal had things the other wanted. 2) The ruling clan is the Trade Hub, which controls interplanetary portals, ala Stargate. One clan could obviously stuff things into a spaceship and travel to another clan to trade, but if it were with any but the nearest neighbor, they would waste time and risk being pirated by their neighbor. The gates -- the hub of the system being the ruling clan's planet -- are the quickest and safest way to trade and travel. ]
[Question] [ Closed. This question needs [details or clarity](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Add details and clarify the problem by [editing this post](/posts/233909/edit). Closed 1 year ago. [Improve this question](/posts/233909/edit) In my world, there exists giant eagles kind of similar to the ones in LOTR. These eagles are large enough to ride and are domesticated. As a result, people have been using this giant eagles in warfare. First, they have been used as scouts. Later on they were used as transports. One day, somebody got the idea of dropping armored airborne knights from the eagles and having them decelerate with big silk parachutes. These giant eagles can carry up to 500 kilograms of weight, can fly for up to 6 hours at a full load, are as durable as a warhorse, and are as rare as elephants. They are taking on human enemies in an early medieval Western European Castles. The castles have archers and trebuchets. Would it be logistically possible for a nation with medieval-era technology to make parachutes for armored knights. If so, would it be practical in combat? [Answer] ## I doubt it's a good tactic Dropping knights will be quite surprising (and a bit funny, too ^^), but alas I doubt it's a very good idea in practice. #### Number crushing > > -We shall rain like angels of death! Oh, lord! Thy are so numerous! > > > An Eagle can carry 500 kg of weight, and let's say a plate-armored, paratrooper knight would weight at least 100 kg : assuming they weight naked 70 kg, add [20 kg for armor](https://en.wikipedia.org/wiki/Plate_armour) and a good [10 kg for a very efficient parachute](https://www.quora.com/What-is-the-average-weight-of-parachute-systems?share=1). To keep things simple, we can say that the eagle can hold 4 paraknights for 100 kg each, and 100 kg is lost for the pilot and any harness, grip and eagle armor it should have. You also told that eagles are as rare as elephants. I read here and there that there were [20 war elephants in some battles](https://en.wikipedia.org/wiki/War_elephant). Let's be very generous and take 50 of them. This means you have 4x50 = 200 droppable paraknights at once. While it's quite high, we have to remember it's a high-estimation, silk cost a lot in medieval times (making parachutes expensive), that 50 people are only there to drop knights (you lose 1/5 of your forces for your main-attack), and outside small skirmishes, battles tend to be bigger than the hundreds. All of this is worsened by... #### Landing into troubles > > -Stay in tight formation, my friends! Oh lord! I'm circled! > > > Airdrops are not very accurate and not all people will reach ground at the same time (because they jumped of or opened their parachutes at different times). Supposing they don't land outside the castle, formations cannot be set-up right after the drop : Paraknights will need time to regroup, if they can ever join their comrades. Being few is already precarious, but combining it with poor formation and preparation makes it a lot worse. Ah and yes, remember they land with the parachute? > > -None shall stand before me! Oh lord! I can't see a thing! > > > They're likely to be blinded on landing as the parachute drops on them, I can already see knights trying desperately to remove the cloth while they're getting beaten up by the defenders ^^. It'll make landing and regrouping even harder than usual. #### Narrowing the distance > > -Hey there are paraknights coming. > > -You know what time is it? Shooting practice! > > > The castle guards will have bows or crossbows. Thus, against any invader which aren't on the line of fire of friendlies will get shot. To simplify a lot1, any paraknight inside the castle isn't likely to be fired at (arrows can reach the other side of the walls, hitting other defenders), but any knight outside is sure to receive an arrow in the knee, if not the head. I know you want soldiers in the castle, not outside, but here's the problem : If there's a lot of wind, your knights will need to take some distance from the castle to land. Beyond the landing accuracy loss, this means they might be in shooting range before they get inside the castle, and risk getting killed before they even land. ## Are there alternatives which still include some kind of airdrops? I know it's not what exactly the epic siege you're hoping for, but here are a few alternatives I can think of which still includes dropping stuff on people : * Ranged weaponry : Arrows, rocks, etc. Since you can throw/drop them from the safety of your eagle, it could cause some damage. However, if eagles are well-known in your world, castle lords will build roofs for towers and remparts to protect against them, or use their own eagles for defense. This could complicate things quickly. * Some rancid cow corpses (and other animals) : It's a biological warfare which was sometimes used in medieval times. The advantage of eagles over traditional catapult illness throwing is that landing in the castle is (mostly) assured. And if you manage to aim the well (supposing it has no roof again), they're really going to need a good doctor. Hopefully it could help devising new strategies for your siege :). --- 1 : There are also cases archers would be able to safely shoot towards the inside of the castle, like when there are roofs, or when there's no soldier on the other side. Having little to no soldier is possible if the other side is against a cliff, or with some coordination if the other side waits knights to land before going out and attack them. [Answer] ## Paratroopers are not front-line soldiers Your specifications make it sound like an attacking force can field a handful of these paratroopers, not dozens or hundreds, and this means that your generals shouldn't be thinking about dropping a large fighting force into a fortified enemy position. Instead, the plan should be to insert saboteurs by stealth, which probably means you'll insert maybe two or three individuals into a fort, and not during the heat of battle. Their objectives will be things like lowering the drawbridge (or preventing it from being raised), unlocking gates, poisoning supplies, spoiling munitions, and interfering with enemy command-and-control (very possibly by last-minute assassination). Fortified targets will begin to take precautions against this kind of thing once it has been used successfully, and that will make it increasingly difficult. That doesn't mean folks will stop doing it, or even succeeding, but both attack and defense will become increasingly sophisticated over time. That probably means these people will not be knights wearing armor: they will be thieves and con-men and silver-tongued toughs who can blend in for a short time, execute some very dirty and violent deeds, and then fend for themselves until their allies overrun the position or they can slip away and return to HQ. The Eaglemen will all have sweet hats and mustaches. In the movie, all their character names will have nicknames in quotes, like: ``` Kevin Costner Robin "Killhound" Hood Kevin McDonald Rodrigo "El Cid" Díaz De Vivar Kevin James Godfrey "Sub-Zero" of Bouillon ``` [Answer] You don't understand what paratroopers actually do Modern Paratroopers rely on being somewhere, where the enemy does not expect any enemies (besides maybe a partisan or two), which is feasible to do with warfare on a country-scale. They are being dropped somewhere, where they can - very locally - gain tactical superiority despite their weak equipment (paratrooped equipment will pretty much always be inferior to that available to conventionally deployed troops, just like your knights DEFINITELY not having full armor). They do this to accomplish some specific goal (eg sabotage and retreat or hold out until the regular forces arrive at a bridgehead). However, castles are small. Really small (when compared to countries, even the largest ones are tiny). When everyone is on high alert during a siege, there won't be a hidden spot for them to land and regroup securely (especially with basic, non-steerable parachutes). Because they usually do NOT drop directly into action. Paratroopers drop, gather their gear together, rescue mates stuck in trees, regroup and THEN march to their actual objective. It takes time from hitting the ground to being an effective fighting force. Even in an absolute pinch you need a minute or two for any individual to be ready, time that you do not have when your drop area has a guard within 20 second running distance everywhere. [Answer] Not armored knights. These knights will necessarily be badly outnumbered if they descend into a castle. Even if you send a bunch, they will come down slowly with their huge obvious parachutes and persons on the ground will have plenty of time to get ready. They will wheel cages under the falling knights then allow the knights to fall in. Then they will make the knights dance for their entertainment! It is not like you will be catching the people on the ground by surprise. They are freaking already under siege! They know you are going to try stuff and they will be watching. They know the knights are going to come down in their city and they control the city. Paratroopers ideally come down behind enemy lines. For a besieged city "behind enemy lines" is outside the city and you already have a bunch of people out there. [Answer] ## No, Because the Enemy Gets a Say Aside from all the other good answers, when worldbuilding you need to always ask how the enemy or system would respond to your proposed change. Ask yourself what you would do if you had a castle and there were eagles around dropping paratroopers. How would you defend your castle? One answer might be to stretch cables or ropes across the castle opening so that anyone trying to parachute in gets tangled in them. Another might be to drag out large sheets of spikes on the ground to impale incoming soldiers. Also, if you had ground attack eagles, would paratroopers be the smartest thing to drop from them? I would think that 500 kg of burning pitch or oil dropped on a Castle would be far more effective. If the Eagles don't like fire, send a bunch of them over to pour oil all over everything, then start firing flaming arrows into the compound. But more fundamentally, in a world with air bombardment and one side having total air superiority, castles would be almost useless, or would be designed very differently. So either they train their own defensive eagles to protect their assets and you wind up with eagle battles in the sky, or they learn to fight and defend in a way that takes eagles into account. Caves and tunnels would be more defensible than a castle with an open roof, for example. Whenever technology improves one side's ability to fight, it will change the the tactics of the enemy. [Answer] # Partly A parachute can be controlled by pulling some ropes that link the paratrooper to the dome, thus a selective drop is possible. For example, dropping on a trebuchet in order to destroy it and prevent damage to besieging troops. But it will be plain more effective to bomb that trebuchet with stones, especially should the eagle have a kind of bombing gear controlled by the rider. Another possible option is to drop a few attackers over the gates in order to open them for outside troops to breach the perimeter. While the gates are held, the walls won't provide enough protection to the defenders, and the roof of a gatehouse is not a good protection from airborne assault, as whoever drops from above could as well drop some stones to create a hole in the roof big enough to pass through. However, as others have said already, knights in flight are very vulnerable to shooting from below, even if a crossbow bolt won't reach the eagles, so it's possible that the strike force will suffer enough losses to fail their task. # As a threat In order to protect a besieged castle, the defenders will have to account for such paradrops, or else a quick drop on the gates could allow the attackers to overcome the local guards and breach the perimeter, thus the defenders will be at a constant stress, lowering their morale over time. If the eagles will also be used as siege weapons (hey you, CATCH!), the castle could suffer enough damage for them to plain abandon it and leave by secret passages. This is the very reason of why artillery effectively disabled old medieval castles as protective centres, and fortification had to evolve into building walls and bunkers for artillery defense. Here with those eagles you have a poorman's artillery with quite a decent precision, effectively obsoleting some of the fortification tricks before the need of them would arise. Finally, about prachutes. One can make a parachute out of sail-worthy fab4ic, and sails were already in place and in at least some abundance to divert some production to making parachutes. Yet, even with parachutes ready as an idea, making a proper parachute and test it for warfare use would take a while, in the meantime other ideas could shadow paradrops as a use for eagles. ]
[Question] [ For the story I'm writing, I have a scene that takes place on a playground. Because I ~~suffer from~~ enjoy World Building Disease, I wound up making an exact plan for the playground. Specifically, it is 40,000 ft¬≤ with some swings, [spring riders](https://en.wikipedia.org/wiki/Spring_rider), a couple 100 ft¬≤ sandboxes, several tunnels, a balance beam, quite a few balance "steps", a fairly substantial "obstacle course" (e.g. climbing boulders, jungle gyms), and a modest "fort" (i.e. platforms, steps, a slide). Now, here is where I have a bit of a conundrum and world building question... This is supposed to serve 24 children. [Similar forts](https://www.playandpark.com/products/structures/glenwood-park) claim to have a capacity of 45 children (just for the fort?). While that particular claim seems ridiculous, even those more conservative estimates I've seen are much higher than my own estimate of 4-5, and I also have a lot more raw square footage. It seems as if my capacity estimate is way off... ... or is it? This world isn't populated by humans, but by anthropomorphic animals. Why is this an appropriate, even necessary, amount of space for my world? ("Because it is not gratuitous overkill, even for humans" is an acceptable answer, if you can justify it, but this doesn't seem to be the case.) (For bonus points, how does age factor into this? That is, does my ratio of equipment to open space need to change depending whether the children or younger or older?) --- Note that the "24 children" target is simultaneous occupancy; that is, a full two dozen children all running around at the same time. They also cover all species; herbivores, omnivores, and carnivores all mixed together (with appropriate supervision, of course!). The dietary ratios are also somewhat skewed; no more than half are "pure herbivores" (i.e. vegetarian), about half eats some mix of meat and not-meat, and a few (2-4) are obligate carnivores. (The latter ‚Äî e.g. felines ‚Äî can and do also eat fruits and vegetables, but generally try to minimize grains, and most of their calories must be from meat.) [Answer] As the other answers have pointed out, 40,000 ft¬≤ is a much larger space than required for 24 human children. However, as the question is asking for justification as for why this space is much more suited to these 24 anthropomorphic animal children, we just need to look at how normal human children and normal animal children compare. The average mobile puppy can easily keep pace with the average human child in terms of speed, and outpace in terms of stamina. Now scale this up so both are human-size, and the puppy would now be able to outpace the human child by a long margin, and as such would require much more room for running about and expending energy than a similar-size human child, probably by a factor of ten or so. As a real world example, my local village children's park is approximately 2,000ft¬≤, while the dog park less than half a mile away is in the region of maybe 12-15,000ft¬≤. Sure, it's designed to cover a larger catchment area, but the simple fact is young dogs need much more space to run around in than young humans. The same goes for many (but not all - tortoises, anyone?) young animals. For bonus points, for younger animal children, I'd imagine you would follow the same principles as for younger human children: less open space; smaller forts; everything much smaller and safer, with more focus on things which help balance, coordination, and group play. Also somewhere for strong adult supervision positioning, maybe raised up above ground level? Or a perch, for Uncle Bulgaria the Vulture to keep his beady eye on the little reprobates. For older children, more room to run and chase each other and get up speed, with jumping and climbing obstacles spotted around for agility and dexterity. Maybe a track around the outside, for the big cats? As I say, you would adjust for age probably much the same as you would for human children. For added bonus points, you should consider adding species-specific items of play, depending on the make-up of your children. For example, as mentioned, a track around the outside, or a long straight section would be ideal for your running animals (big cats, horses), with jumps for the deer. A climbing frame would be a requirement for monkeys (monkeybars!), lemurs, sloths, etc; perches and hoops for birds to fly through; a mudbath for the hippos.. You could have a bit of fun with the details, depending on the level of anthropomorphising(?) you wish to do to your children-animal hybrids. [Answer] Current use is not what builders expected. There is a playground about a mile from my house. When I discovered it I was surprised. It was brand new and wonderful and hardly being used. Around it were vacant lots and condemned houses. An enormous abandoned Sears distribution center loomed a block away. The city put the playground in first. All of those lots and houses are gone now, and there are apartments. The distribution center has become a bunch of upscale shops, with apartments above them. The playground is now full of kids all the time. Your playground was built with the expectation of higher occupancy than it currently has. Maybe it is new and the developers expect more kids in the future. Maybe it is old and there used to be more kids filling it up. Either way, the excess space gives energy to the story. The expectation of more in the future or the memory of more in the past both give energy to a present where there is less. [Answer] 40,000 square feet for 24 children amounts to almost 1700 square feet of space per child - that's the footprint of a modestly sized house for each child! This should be plenty of space for activities that require wide open spaces, as well as stationary installations like slides and swings. This playground could easily handle a much larger capacity. As a point of comparison, a professional basketball game has about 4x the density of adults, with 10 individuals in 4700 square feet (470 square feet per person). An American football game has a similar density to the proposed playground, with 22 adults (plus referees) on a 48,000 square foot field (2100 square feet per player). If you've ever watched an American football game, vast swaths of the field are completely empty most of the time - there is plenty of space. Age could play a factor, in that less space would be required for smaller children. They don't run as fast or as far as older kids, and playground equipment sized for their age will be smaller than that for bigger kids. [Answer] This playground should accommodate megafauna and possibly even dinosaurs 40,000 ft¬≤ is very large for 24 human children. It comes to 1,666 ft¬≤, which means that human children are not going to have much contact with each other. However, if we need to accommodate children of larger species, it all makes sense. If you see the movie "Zootopia", there are different areas and establishments for different species. While smaller species have the right to come to larger species' places, those places are designed first and foremost to accommodate those larger species. So, while 1,666 ft¬≤ is a lot for a human child, it's not that much for baby elephant, and for juvenile sauropod it begins to look too tight. Now, how children of different species can play together without stepping on each other is a different question, which would likely be answered by allocating different time slots for differently sized children. [Answer] The playground playacre1 you describe is large enough for 24 children, but just barely. It would help if you could make the sandboxes bigger. Allow me to explain -- A sandbox that's 100 square feet is basically 10' x 10'. Let's assume both sandboxes are identical, that each sandbox is surrounded by a wooden retaining wall that rises 1 foot from the ground, and also extends 1 foot below ground. That depth is maybe not typical in the real world, but deeper is obviously better because of more law2: ``` more volume == more sand == more sand ``` I assume that typical playground sand is just [regular sand](https://en.wikipedia.org/wiki/Sand), and thus has an [angle of repose](https://en.wikipedia.org/wiki/Angle_of_repose) of approximately 34¬∞, so it seems reasonable that children could remain completely covered if they dig all the way to the bottom of the sandbox and lie perfectly flat. (Obviously on their backs, and with some kind of straw for breathing, like a snorkel.) This will actually be made even easier if other children are at the bottom of the sandbox too, displacing more sand, which they would be. But neither sandbox can hold the 11 children necessary for an even split. I've tried a few different packing schemes on graph paper, but if all the kids are kind of uniformly biggish, and the sandbox is square, the most I can fit into one sandbox is seven. If we assume 14 children can fit in the sandboxes, that still leaves nine unaccounted for. "Several" tunnels means at least three. (And per [Willk's Proviso](https://worldbuilding.stackexchange.com/a/206464/19221), there are no take-backs with plurals.) A boulder can do in a pinch (but is obviously not ideal), and you used the plural, so that's two. I've never seen a playground with fewer than two spring riders, so that's two more hiding places (especially if any children have spring-like appendages, or plausibly look like [spring riders](https://americanswing.com/wp-content/uploads/2019/08/SP200_Catepillar__47488.1286907444.1280.128065303_nobg.png) themselves). The fort is frankly too obvious, but there's always one dummy who goes for that stuff. (The tunnels are not dumb, because tunnels are dark and it takes a brave kid indeed to crawl into a dark place filled with creepy-crawlies and then sit silent and motionless as the local arthropods come a knocking.) The balance beam is worthless unless it's large, and even then, the kid would need to levitate like a magician's assistant. A jungle gym is an obvious trap: you can see right through the thing, and most kids learn at some point that it's safest to stay away from one rather than run the risk of getting caught trying to clamber out of it when poop meets fan. So that only leaves the balance steps. If [this](https://dk22sb66g7qaa.cloudfront.net/aesir-dam-viewports/balancing-and-climbing-category-slider-1920.jpg?rel=2020-02-10+14%3A43%3A59) is what you have in mind, we've still got one kid left. You didn't mention any trees, bushes, or other substantial vegetation; any embankments, gullies or ravines, streams or other bodies of shallow water (and anyway, shallow water is translucent -- or if it's not, it's a lousy hiding place). Your question was: > > Is this a reasonable scale after all, even for humans? > > > We're so close, and I really want this to work, so I'm going to assert there's at least one tree with decent foliage, and at least one of the kids can climb it. So there: 23 hiding places. But the seeker is really going to have to project, or nobody will hear when the countdown ends. And each group of kids can really only play one or two games before they realize the possibilities have been exhausted. --- 1 1 acre = 43,560 sq ft 2 not to be confused with [Moore's Law](https://en.wikipedia.org/wiki/Moore%27s_law) [Answer] Rich People The playground is funded by a rich person or several rich people to provide a fun place to interact for their children. Either that, or the playground is in a really rich part of the city. As we all know, there are rich people who spent an atrocious amount of money on extravagance. Spending some money on a large playground for their children seems like one of the more reasonable uses of money. It's in the Countrysides There are rich farmers. Land in the countryside are cheap. Why not? It's for a Luxury Resort/Amusement Park Think Disney World, but for rich people. Society is more advanced or productive Maybe it's far in the future where people have a lot of land. Society now expects people to have a lot of space to work with. Free-ranged children develop better. Animals Run Faster and Need Bigger Space to Play We all know that cheetah cubs need lots of space. Free-ranged cubs ~~are tastier~~ develop better. [Answer] You're over-thinking it. Which is awesome. Playgrounds serve a variety of purposes apart from simple entertainment. They are (nominally at least) safe areas for children to engage in physical exercise, imaginative play and (often mediated) social interactions. Learning to play with others, share limited playground equipment etc. is good for their social development after all. What we don't tend to acknowledge is that playgrounds are places where children can be exposed to mild physical danger, where they can (and do) challenge themselves and others to do stupid things and end up with minor injuries - scrapes, bruises and so on. This teaches them to be confident, to accept minor hurts in the pursuit of sweet victory, to dominate their peers... uh... compete with their friends in a relatively safe environment. In your case you have a mixture of different base types, perhaps with their own individual needs. The carnivores need high energy, burst activities - things they can chase, climb, slide down, bounce off, swing from, tumble in. Herbivores are more likely to need space to run, cooperative activities, some quieter spaces and a few activities devoted to strength rather than fast reactions. Omnis are just going to do whatever, because they're like that. So you need space to chase each other around in, things to both climb and hide in, preferably in colors bright enough to cause retinal burns because what kid doesn't love radioactive green slide sets? It needs to be spread out enough to let them pack up, chase or be chased, because going without these developmental experiences will leave them emotionally stunted, socially inept, unable to deal with minor troubles. Gee, just like ubiquitous connectivity did to the last couple of generations. Who knew? And now we've arrived at the more serious part of the answer. Because your society has a mixture of different animal types, it is critical that the children are raised to maximize the social stability between the groups. Not doing so will tend to damage society as a whole as the younger generations grow up as more insular, less able to handle interactions across the food boundary, more prone to distrusting or outright hating those that are different. The founders of this society have studied the problem extensively, and social scientists have determined the minimum requirements for adolescent socialization. They've produced a set of guidelines that any shared play space must allow, and mandated that space be assigned for these play areas within the community based on population and other factors. And it's these rules, formulated for the good of the society, that result in your playground being the size that it is. For other communities or areas with a different distribution of children the parks will be different. Your area has this size park because it's what the guidelines require. [Answer] I don't think it is outrageously oversized. That is only 200 feet per side, less than 100 yards. The thing is, a playground doesn't have an importance to density. Twenty-four children running around and playing on a 200' by 200' space would be fine. They don't have to use the whole thing. They won't have to spread out to their own isolated spaces of their proportion. They play together somewhere in that space. It does not have to be near capacity. So if 45 is the capacity, a few children might play there quite fine. If space is not limited then I think it would be perfectly reasonable for them to have built a 200' by 200' playground, not really tailoring it to, "Only about 24 children would ever be using this." ]
[Question] [ Let's say that we all have digital chips implanted into us as babies which are embedded deep into our nervous system and hooked into our senses- short of surgery, which isn't an option in this world, how could a person disable, even temporarily, such a device? I was wondering if building a faraday cage would work and then entering it when you wanted the chip to be inactive? But I'd love to hear other ideas or issues. [Answer] Shielding is a solution when you need to prevent the embedded chip from communicating with some external system. Using Faraday cage or just going outside the range of network is the least invasive method, but is usable only when the chip is meant for sending data out or receiving something. This includes the passive RFID-type tags that send respose to certain radio frequency. When the chip has some some other function, for example affecting some biological process or acts as a recorder, then the shielding has no effect. To prevent the chip from functioning, one must either: 1. Hack the software. 2. Attack the chip physically by using focused ultrasound or microwaves. Such methods are used in real life medicine to ablate fibrous tissue, break kidney stones etc. The effect will be permanent. 3. Alter the biological environment so that the chip fails to function. There must be some biochemical interface that connects the electronics to nervous system. One could find certain drugs that make this connection to go haywire. Like LSD or something specific that the people of your world have discovered. [Answer] All natural solution If the chip's relevant activity is detectable, biofeedback may be a possible solution. While observing the chip, maybe with a receiver or EMI detector, one trains oneself to selectively shut down or bypass the neural connections being monitored. As a plot point, you can set the difficulty of learning this skill to where only 10% bother with the training, or that only an elite few can master it, so it's fairly flexible. It could even be possible, but extremely rare, to find individuals who can hack the feed, for instance by feeding it an imagined or remembered scene rather than their current field of vision. [Answer] > > it allows the company to see through the eyes of the person > > > The human eye is roughly equivalent to a [15 Megapixel](https://www.discovery.com/science/mexapixels-in-human-eye) camera and has a frame rate around 60 fps (your visual system is way more complicated than that but it's a useful analogy). If your brain-chip is recording using 24-bit color, it's having to process ~2.5 GB of uncompressed video data every second. Processing and transmitting that much data will require significant bandwidth and power. Blocking the chip's transmissions should be easy enough: either block the signal (shielding or a Faraday cage), drown it out with EM noise, or set up a counterfeit base station for the chip to transmit to (similar to how some law enforcement agencies intercept and re-route mobile phone traffic). If the chip can detect communication failures and buffers the video feed for later transmission, defeat this easily by blocking the signal for a longer period of time. Given the rate at which video data is being generated, buffering will be limited to fairly short bursts. Block the signal for longer than the buffer length and some of the data will have to be overwritten before it can be transmitted. If you can't block the signals, you can always use the Spartacus defense. Hack many people's chips to all report the same person ID. When the company receives a flood of different signals all claiming to be Spartacus, there's no way to tell which video stream is the real Spartacus and which are the imposters. The fact that the chip needs to transmit means that the chip has an antenna of some sort and isn't completely shielded. A strong rotating magnetic field (an MRI machine, for instance) could induce enough electrical current to fry the chip or melt the antenna. The other way to disable the chip is by attacking its power source. If it runs off of an implanted battery that has to be occasionally recharged, simply "forget" to recharge it. If it runs off of the electrical energy produced by your nervous system, reducing the amount of available energy (via drugs that inhibit the nervous system, extreme starvation/exhaustion, etc) should disable the chip. I'm assuming the chip includes a protocol to shut itself down in such cases to help the host survive (the chip wouldn't seem useful if it killed the host). In the real world, video processors can be hacked by forcing it to process a carefully-crafted video stream that [exploits](https://www.maketecheasier.com/hackers-exploiting-vlc-vulnerabilities/) defects in the processor's design, causing it to do things it was never intended to do (such as run code written by the attacker). This becomes much more interesting when that video stream comes from the eyes, as it means that looking at a certain painting or watching a certain video clip could cause the implant chip to crash and give the person a short window of time before the surveillance system comes back online. You said surgery isn't an option. If you only meant that to mean invasive surgery, then something like the "[Gamma Knife](https://www.mayoclinic.org/tests-procedures/brain-stereotactic-radiosurgery/about/pac-20384679)" procedure could be effective. Many small beams of radiation are fired at the patient from different angles. Each of them is far too weak to affect anything. They all converge at a single point, though, and at that one point their combined power is capable of burning away tumors. A system like this could non-invasively destroy or disable the chip permanently. [Answer] Use another chip. [![enter image description here](https://i.stack.imgur.com/IFO3e.jpg)](https://i.stack.imgur.com/IFO3e.jpg) In the movie Speed, the camera monitoring the bus is fed a looped video of the bus interior, so the bad guy does not know that the passengers have been evacuated. So too in your scenario. The bad chip receives inputs from the optic nerves that lets the company see thru the eyes of the chip carrier. Use a second chip to work around that. Clearly this world has advanced neural chip tech. The second chip might feed the first one a stream of data from a different individual, or prerecorded data. Or the second chip could produce inputs to the visual system from an external camera or device - so the chip carrier seems to be asleep with eyes closed, but can see via the camera - brain (or nerve) interface. I like this because your fiction has nifty brain chips. Then when you need a workaround you are true to the theme: even more nifty brain chips. Also it gives an option for how the company discovers what is up - the chip carrier is supposed to be asleep with eyes closed, but the company gets data on taste; she is eating wasabi. And so is unlikely to be asleep. I hope when he finds out the bad guy rages like Dennis Hopper in Speed. [Answer] An EMP (electro magnetic pulse) can damage electronics. People with pacemakers are told to avoid strong magnetic fields because they interfere with the electronics inside. So maybe your chip could be disabled with a strong enough magnet. [Answer] Bio-engineer a bacteria that really likes the "taste" of silicon/whatever else is in the chip. The bacteria would need to be able to cross the blood-brain barrier. Then, once it's in your blood and crosses into your brain, it starts "eating" the chip breaking it down. You'd also then have plausible deniability when the authorities realize your chip doesn't work. You could claim "I didn't know I'd picked up this disease!" even if you intentionally injected yourself with it. Or, maybe the disease is naturally occurring, and now your protagonist has to go on the run because their chip was disabled by the disease. [Answer] If it is deep in or Nervous System, getting it out there is probably not easy to do. If the Chip isnt shielded, a small EMP or maybe just a Strong Magnet could do the job. But if it is shielded, yeah you are kind of out of options. A Cage would only work to Block the Signals, but the Chip itself still does its thing so it would just record everything you do. I mean, it would be logical do designe it in such a way as people will be out of range sometimes, or have no signal. Maybe it even has some sort of Self Learning Algo in it that compresses the Date more and more so you can record a life worth of information on a few Gig´s. Disabling the Chip, depending on what it does and what it can do might be close to imposible. It is at such a critical point of or body that even a slight error that blows the chip would result in you being disabled too. MAYBE, you could "hack" it or flash the Software and disable it that way. Idea: You know how, when you flash the BIOS of a Motherboard and the power turns of, your Motherboard is dead. It has no software to run with. Maybe you could do something like that with the Chips. Idk they get Updates once every Week or so or just do a System Check and if you manage to cut power during this time, the Chip is dead as it has no software to run on. It stands to reason that the Chip has some sort of UI for the Government to extract data even if the Transmitter is busted. So you would probably be able to send in some code that Cuts power, maybe you force the chip to restart during a BIOS flash which kills it ? In the end, it is a much better option to try and kill the software then to try and kill the chip. [Answer] You can permanently fry any electronic device using an EMP. A nuclear EMP would probably be too conspicuous in the scenario, but there are non-nuclear EMP generators; their operating principle even has a Technobabble but is real: Explosively pumped flux compression generator. I don't understand all operating details, but it seems they all work by manipulating a magnetic field into smaller and smaller areas, forcing it to become strong enough to generate an EMP in the final phase. It seems that this cannot be done purely mechanically or by switching electronically, you need explosives to make the process fast enough, plus some pretty sophisticated setup to make the individual components of the circuitry break down in the exact right order. More details can be found at <https://en.wikipedia.org/wiki/Explosively_pumped_flux_compression_generator> The nice thing about this approach is that such devices aren't easy to construct (if they were, people would be frying brain chips routinely, defeating many purposes of such chips). [Answer] Stay away from whatever electronics it is that the chip interfaces with. [Some people already have chips in them](https://www.usatoday.com/story/tech/talkingtech/2017/08/01/wisconsin-employees-got-embedded-chips/529198001/). This link is from 2017, and even yhen it was old news. Technologies for microchipping such as RFID have it so that chips have no internal power source. When they are scanned or otherwise activated by a radio signal, the electromagnetic field from the signal powers the chip temporarily. The chips are so small that the radio signal probodes enough energy for it to operate. A Faraday cage may help your chipped people disconnect for a while, as long as the energy source for the chip is outside the cage and the cage has small enough holes (or no holes at all) that the signal frequencies are effectively blocked. [Answer] To Prevent Sending Signals I am going to assume, based off of your comment, > > it also allows the company to see through the eyes of the person. I'm hoping they can find a way to stop this effect, > > > that all you want to do is prevent the signal from "calling home." One potential solution: Wireless Jamming Wireless technologies that emit their signals on a certain frequency can be jammed by a device that emits a tone on the same frequency that is much stronger. In comparison to humans, if you shout really loudly next to two people trying to carry on a conversation, they won't hear each other, just you screaming. That's kinda what's happening with the devices. Now, there are countermeasures to this. Some devices, while they can't prevent the jamming from happening, they can detect it, record the event, and send an alert once the jamming has stopped. To stop the chip from working entirely A chip will have ratings for the current that can safely pass through it. If you exceed these ratings then you will likely fry the chip. Amperage is a deadly thing to humans, but to an extent, voltage can be very nonlethal, so if you can find a way to hook yourself up to a low-amp electrical current, you could keep testing higher and higher voltages until you fry the chip. [Answer] You probably don't want to remove it, since any society that insists on "chipping" its citizens is probably uncool with that. That said, spoofing location data, visual data and auditory data may well be possible without modifying the device itself. [Answer] You need to want it enough See the thing about brains and neurons is that they're adaptable. Our brains are squishy, and not just to make zombies' lives easier. Our memories, consciousness, experiences, they're fluid things. Who you are 20 years ago is not who you are 20 years in the future. Neurons adapt, grow, die, change. One of the most human things about us is our abnormally large prefrontal cortex. It allows us to disregard instinct. We can fast for religious reasons, commit suicide or other atrocities that nature would deep counterproductive. This is possible because we have such control over ourselves, because we can adapt. The power of the brain over the body is immense, see the placebo effect. There is also an inverse, the nocebo effect, that can make you sick if you simply believe it hard enough. People have had whole halves of their brains removed, and managed to regain what would be unthinkably normal lives. This is all evidence for our brain's ability to change itself, and for our ability to adapt. If you want this chip to do nothing, if you want it hard enough and for long enough, the neurons connected to the chip will eventually up and stop firing altogether. If you see the chip as a foreign substance your body will attack the chip with its natural defenses like any other invader. [Answer] It depends If the chip is just like an ID card, your bus ticket and security pass for work, making it inactive would probably not be the smartest idea, but you'd eventually want it back on again. so to stop it temporarily, a faraday cage would work, but you wouldn't be able to get into work, hop on the train, etc, unless your civilization has physical security badges or paper currency. If the chip is there to look through you're eyes, then you'd best go blind. maybe put on a sleep mask to block the view, and have a seeing eye dog(unless they put the chips in dogs as well), or a friend help, but they probably also have a chip. if you don't really care about the travel times or accommodations, mail yourself to your destination while blindfolded. If the chip is a fail safe for if you try to kill someone, then you best not give them a reason to hit the kill switch. faraday cages might work to stop the detonation sequence, but if they are continually broadcast until they get a success message back, then you need to keep the faraday cage on or forge the success response. If the chip is for basically anything, hacking is probably one of your best options. this would probably let you decide what the chip is doing, and avoid anything you don't want interacting with your chip. Basically, Your solution depends on the problem [Answer] ## Ultrasound, Terahertz, or Gamma Knife For example, [this](https://www.webmd.com/brain/news/20190529/breaking-the-ultrasound-barrier-to-fight-disease). The goal is to focus any form of transmitted energy onto the foreign object and damage it sufficiently. ## The great god Amok "Unfortunately, no one can be told what the Matrix is. You have to see it for yourself." [Answer] How about just wearing magnets around your neck? I mean like refrigerator magnets. I suppose this would work only if the government had a lot more control over what you were exposed to. You could have them remove any mention of magnets being available like that so none would try to use them but then someone finds them in a box of junk they fall face first into and they realize it interrupts the signal. ]
[Question] [ In my fantasy world, there are people that can insert their consciousness into another body, basically creating a mental clone of themselves. However, they need human sacrifices to do so, as dead bodies are the only ones that this can be done to. However, the bodies under the magical influence decompose quickly, and after a few days are completely useless piles of flesh and bone. So, these magic users need a way to sacrifice people while dealing the least amount of physical harm, as to prolong their stay, but how? The kicker, however, is this takes place in a fantasy world (if you didn't already guess) and has technology equivalent to that of Imperial China as well as some extensive knowledge in anatomy, specifically around the brain and about blood and veins. Also, they have limited access to the outside world so poison is out of the question. Lastly, it is a public, in-the-moment religious event with hundreds of people watching, so some drama should be involved. Edit: I understand that torture for entertainment and asphyxiation is a good alternative, but for plot's sake, I am wondering if there are other possibilities. Leave any questions below. [Answer] As one way of leaving the victim of a public execution sufficiently intact for a magician to use it as a meat puppet, let me present: ## Public Drowning In this method, the condemned is brought to the place of execution, where a large, tall, thick-walled glass vessel stands, filled with water perhaps half-way up. There is a platform around the top of the vessel, and the condemned is brought up to it, possibly stripped off so that it can be shown that the condemned has no breathing tube hidden in their clothing (and to titillate the crowd), their feet shackled to a metal gridwork platform, which is then slowly lowered into the glass vessel, where the watching crowd can observe the condemned's slow descent into the water and their death struggles as they descend below the surface, and even approach the vessel and jeer at the condemned through the glass. For criminals convicted of the more heinous crimes for which the sentence is execution, the experience of drowning can be repeated many times, submerging the condemned until they fall unconscious, then swiftly extracting them, reviving them and repeating the process. For more entertainment, the heavy metal grid to which the condemned is shackled can be lowered on ropes, and the condemned's hands left unbound (but unable to undo the shackles, which would be locked or bolted closed) so that they can hold onto the rim of the vessel and keep themselves above the water until they tire and lose grip and fall into the water, or for more certainty, the grid can be lowered on poles, so that it can be pushed down. The glass vessel need not be as clear as modern glass to be sufficiently clear to serve the purpose of allowing others to see a person inside it, and glass is a material known since ancient times. For more entertainment, this means of execution is not 100% certain. The condemned may smuggle in a key for the shackle locks (Chinese locks were pretty simple) or may secrete a length of tubing in certain body cavities, thus prolonging their struggles, or both. Where the authorities really want someone to die, such devices could be "overlooked" , but there could be guards above who could remove any breathing apparatus after some time (or pour water into it), and if the condemned gets free of the shackles, guards could close a spiked grate over the vessel and if necessary, stand on it. Otherwise, stripping the condemned and conducting a last-moment body-cavity search could both eliminate such possibilities and further titillate the crowd Another option, if rainfall is heavy and common, is to place the condemned in an empty vessel for a certain amount of time, but the vessel will be filled by rainfall collected from nearby roofs, leaving a degree of uncertainty as to whether the condemned will live or die, depending upon the "will of the gods" (more accurately, the vagaries of the weather). The beauty of drowning for this purpose is that it does relatively little damage to the body, and unless fatal, can be treated fairly rapidly, leaving the victim capable of action shortly thereafter. Lung infections may be an issue, but if the magic that makes a body into a meat puppet is as destructive as the OP says, then that won't be an issue. One possible drawback of this method is that drowning tends to lead to raised blood pressure that may result in burst blood vessels on/in/around the eyes (potential partial or complete blindness) in particular, but also visible on the skin on other parts of the body and/or cerebral haemorrhage (strokes) that may leave a victim in a less-than-completely-useable state, but this will not occur in many cases. [Answer] How about this [![enter image description here](https://i.stack.imgur.com/SX11d.jpg)](https://i.stack.imgur.com/SX11d.jpg) [Source](http://www.dailymail.co.uk/sciencetech/article-3433900/Are-gruesome-inventions-history-Ancient-Greek-bull-boils-victims-choke-pear-inventors-come-horrifying-devices-cause-suffering.html) But instead of using fire stand the bull half way up in very cold water just above freezing. Make sure that the victim has not been fed for a few days and is soaking wet when put in. Add further cold water into the bull as required and ensure the water remains very cold by adding ice but don’t let it freeze. Hypothermia should set in relatively quickly and the victim should be well preserved as well. [Answer] Just shock the heart to stop it using iron paddles wired to [this ancient battery](http://www.bibliotecapleyades.net/ciencia/ciencia_hitech05.htm)... [![ancient egyptian battery](https://i.stack.imgur.com/DBu4E.jpg)](https://i.stack.imgur.com/DBu4E.jpg) It isn't very torturous and aside from the magic of the electricity, there is little theatricality to it, but the body is in tip-top shape for occupation after the show is done. [Answer] Disclaimer: These magician types are real bad news! Expect any neighboring peoples to be grossed out by their habits and launch the occasional crusade against them. That said... There are two countervailing factors here -- excitement vs intactness. As you increase one, you tend to decrease the other. Pretty much anything with anvils is off the table. But let's see what we can do. Assumptions: * We don't want to break any more bones than we have to; dead or not, you need the skeleton available to support the body * The clones only last for a few days, so they won't need to do a lot of eating * Nervous system must stay +/- intact, so no spine play * Breathing is purely optional * Removed organs don't rot (well, they do, but they're out of play) * You want to have the skin & features in decent shape Okay, given these assumptions, here are a couple ways to go: Evisceration Make a small incision in the abdomen. Then start ... pulling things out. You can make this as theatrical as you want. The key is, you are leaving the skeleton intact, and the skin nearly so. When you're done, rinse out the insides with salt or alcohol solution, stuff it with sterile gauze, and sew the "participant" back up. Big crowd-pleaser, this one. Evil Cirque du Soleil This one focuses way more on the spectacle than anything else. Tie up your participant and swing him, pendulum-like, through an "obstacle course" of flames, blades, leaping piranha, and so forth. You are essentially trying to force the participant to die of fright. If the show starts dragging on, open a vein so that he's guaranteed to perish, as well as artistically flinging a fan of blood all around. Challenging Assumptions Side note here ... how long would a mummified corpse last? Is there any interest in "preparing" the participant to try to make the body last longer? If so, you could go through the whole mummification ritual onstage... [Answer] Crows cage, stick a person in it and let them die of dehydrations. Of course part of the point of the crow cage was letting the body rot in the cage so getting the body may be an issue. [![enter image description here](https://i.stack.imgur.com/ScZ8S.jpg)](https://i.stack.imgur.com/ScZ8S.jpg) Alternatively crucifictions (which normally involves tying the person to the cross) where the person dies of asphyxiation. Both were rather common forms of execution. [![enter image description here](https://i.stack.imgur.com/vE4fW.jpg)](https://i.stack.imgur.com/vE4fW.jpg) Alternatively short rope hanging (or short drop hanging) does not do to much damage, it will leave a mark on the skin of the neck, but otherwise it is all strangulation, as opposed to long rope which kills by breaking the neck. And again very common form of execution. [![enter image description here](https://i.stack.imgur.com/En36s.jpg)](https://i.stack.imgur.com/En36s.jpg) [Answer] I'd suggest exanguination - drain them of blood. It's good for execution, because there's a variety of options - from the ones where they're painful, to actually relatively painless depending on severity of crime. But you do get lots of blood all over the place, which is good for an execution, especially if you've a ziggurat or altar for the blood to flow down. You can trigger it quite easily with just severing a key artery or two - the femoral artery (in the leg) or of course, the juglar in the neck if you're trying to go fast - or other locations if you want the bleed to take longer. You've excluded poisons, but perhaps anti-coagulants might be available? Asparin is a pretty low tech thing (tree bark). But if you really want dramatic - how about death by leeches? Sit them in a tank, and let the leeches feed - they'll drink their fill and 'drop' off' when they're done. But if you've got enough leeches, it'll drain them dry. (It's probably not too painful a way to die, because they actually inject an anesthetic. But it'll be squicky and look scary.) [Answer] 5 Palm Exploding Heart Technique!!! [![pic of title](https://i.stack.imgur.com/5wMuF.jpg)](https://i.stack.imgur.com/5wMuF.jpg) No but realistically, the human heart can be hit with enough force to cause an Arrhythmia resulting in cardiac arrest which if untreated results in death. so a good super punch to the chest is a clean savage way to do em. This occasionally happens in American football where someone gets tackeled just right. FYI, a normal human punch isn't powerful enough, you need slightly more strength and precise targeting. Like Dwayne Johnson and bruce lee put together. Why this is good, it's reversible in the sense you just need a similar jolt the heart to get it moving again. You just need to wait long enough for higher brain death to occur Roughly(2-5mins). If you restart it soon enough you can prevent total brain death allowing for the body to maintain itself and allow you control. This is because the parts of the brain responsible for biological sustainment are more resilient to this sort of abuse. This is why some brain dead patients can survive without life support for days. [Answer] Specially trained executioners (or priests, depending on how you want to take it) that strike the chest at a specific moment to interrupt the heart rhythm and stop the heart. See <https://en.wikipedia.org/wiki/Commotio_cordis>. The ritual experience occurs as the "priest" becomes attuned to the victims heartbeat and requires silence from the audience so that the killing strike can be delivered at the right moment. There's also the possibility, in rare instances, of reviving the victim after the original mind or soul has departed, effectively giving the mental clone that is taking over an actual living body to inhabit. [Answer] A sealed box entirely made of armored glass (was invented in 1625) with optics treatment (around 1590) to make the agony more theatrical and dramatic Otherwise, pillow on the face and that's it. Theatrical value will be poor but effectiveness is granted EDIT: additionally, you could try long needles in heart and/or brain, voodoo style stuff, but don't know if it qualifies as harmless ]
[Question] [ An evil empire is besieging a floating city. While not particularly high off the ground, none of the siege weapons can reach it effectively. They also need a way to get troops into the city. An imperial engineer comes up with a design: > > A large ballista fires a glider as far as it can into the air. The glider is essentially a smaller, winged ballista that fires once it reaches its peak height. The idea is to have the second projectile tied to a rope, allowing soldiers to climb up to the city. > > > Some background info: * The world is low magic fantasy. The city floats by unknown powers, and there are no magical flying machines. * The city is situated on a plain, so the ground around it is relatively flat in every direction. * The tech level is between medieval and industrial revolution, however gunpowder and airships do not exist yet. * The height at which the city floats at is not set in stone. This can be adjusted. EDIT: * The city is stationary. * Each nation is a single city state, barring the Empire, which is consuming nations one by one. * The nation being besieged is a nation of scholars, scientists and strategists - some of the greatest minds in the world. * In order to minimize reliance on the ground, the city has a self contained water system. The inhabitants have a large view radius, and thus have fair warning of the approaching army. All non military personnel are evacuated and take refuge in friendly neighboring states, leaving only the small but efficient army to man the battlements. The king and his son remain to command the troops. With only a few hundred men, the preserved food stores would allow the defenders to hold out long enough to make a prolonged siege very costly. At the end of the day the city must fall for the story to progress, but I can't think of a way without airships/magic to do this. I could allow gunpowder and have them blast it out of the air, but I need enemy soldiers to infiltrate the city for plot reasons. Is this two-stage ballista solution plausible, and if not, what alternatives/alterations should be looked at? EDIT: I'm strictly looking for mechanical solutions. Assume that the defenders are extremely loyal and have the greatest disdain for the enemy Notice: Apologies for not replying to comments etc. I kinda have a medical emergency, but will go through everything once it's passed. Thanks for all the answers! [Answer] A glider light enough to be launched a good distance in the air, yet rigid and resilient enough to bear its own siege weapon, seems a bit infeasible. I suggest altering the plan in a couple key areas. For one, using a trebuchet or similar design to launch the initial payload would likely be more practical. These are by far the best distance launchers available to the low-fantasy medieval theme. Instead of the glider, let the payload tumble freely, but have an exceedingly clever mechanism built into it that will disengage once its airspeed falls low enough, at the apogee of the launch. Said mechanism will release one or more parachutes to unfurl and slow the secondary stage further. This accomplishes two goals. The first, the drag from the parachute as it start to fall will help assure the dangerous end of your payload is pointed upward. And secondly, the tension from the connecting lines will pull on the attachment points to trigger the secondary weapon to fire upward into your target, or over the wall, depending on whether you trust your low-tech rocket scientists to get the orientation close enough to launch at an angle. The descending second stage will carry the cable down to the ground, possibly on a spool to allow it to uncoil cleanly. As a bonus, if your engineers are up to it, it could double as a crude elevator with man-power ratchet mechanisms to lift your forces up to the target! [Answer] The two-stage ballista with a glider sounds very cool but is bound to fail, mostly because a primitive glider would either be too fragile to survive the launch or too heavy to get anywhere near as high as a simple harpoon fired from the same ballista. Even modern gliders can only gain altitude when they fly in rising air (thermals or wind over hills/mountains) to use, so it's highly doubtful your first generation experimental contraptions could. Your goal is to have enemy soldiers infiltrate the city without too long a wait, so simply building a hill next to the city for your siege engines is not an option. Still want to fly? Try a balloon If you are okay with gliders, you might want to consider a primitive hot air balloon, the type they could fill from a bonfire underneath the city and let it ascend while still attached with long ropes. You'd need one or two suicidal fools to get in and fire grappling hooks from crossbows and hook them to the city's underside somehow. Plan B: Ballista with firework rockets! In China, fireworks existed for centuries and were even used in warfare to a limited extent. It wasn't until much later that people figured how to really make gunpowder explode with much force. If you are willing to allow "low-explosive" powder that doesn't work for cannons or guns, you could have rockets to carry up a rope or wire to attach to the city. And if the rockets by themselves are not strong enough to cover the distance, you could first launch them part of the way with your ballista. The nice part here is that you can make this very rare and exclusive. Perhaps the evil emperor traded a fortune away for a handful of these from the only nation that knows how to make them or maybe the Alchemist that created them dies in a testing mishap. Either way, the sky is not going fill with rockets soon, it's a very special one-time affair, saved for assaulting the floating city. One addendum: The smokescreen Both these solutions are not-quite-stealthy, especially if the defenders keep watch from the bottom of the city. To protect them from being spotted and generally make life unpleasant for the defenders, the evil army should bring wagons with large kettles of oil that they burn to make a smokescreen, moving the wagons as needed to be upwind of the city. They can substitute grass/leaves etc if oil is in short supply. [Answer] Start a fire under the city. Spend a week or two cutting down surrounding wooded areas and breaking up nearby buildings. Pile all the wood up under the city to create a giant bonfire. Wait for a day with relatively light wind and set the whole thing ablaze. If the city was low enough to the ground it would turn into a giant frying pan, but if it were higher the main danger to the garrison would be the smoke, completely filling the city. Fires create updrafts of the sort depicted below: [![firestorm](https://i.stack.imgur.com/Xi8CA.png)](https://i.stack.imgur.com/Xi8CA.png) While the garrison closes every window and retreats to the deepest recesses of the city to escape the smoke your troops can use gliders to ride these updrafts straight to the city. They would perhaps need some magical or technical protection against the smoke, but if they stay near the edges of the column they could likely manage it. [Answer] # Tackling an enemy's strength head-on is a good way to lose The city's great strength is it's inaccessibility. That's difficult and expensive to overcome. Don't bother. The city's great weakness is it's population...who are conveniently on the ground in nearby states. Attack that relatively unprotected population. A truly great, scene-chewing evil emperor should revel in such malevolence, and in the many opportunities for deceit and horror and betrayal implicit in that strategy. Why would any evil empire worthy of the name hesitate to raid nearby neutrals? The city's King has chosen an unwise strategy - his lone battalion of soldiers do not seem to have enough mass for an effective sortie, and can be bottled up by a mere brigade of the empire. The scenario seems to require that the City has minimal useful advantage from it's elevation - which is a shame, as simply dropping hot/hard/sharp/poisoned/infected/gruesome objects onto the vast army gathered below seems an obvious defense. The evil emperor seems free to send the vast bulk of his forces raiding. In a year or two, the siege will be over, and the empire will own the floating City of The Starved (or the City of The King Who Caved) while the city's children toil in misery below as the emperor's slaves. I know this isn't the answer you're looking for - it's not a way to storm the city, there's no fantastic battle, no heroic defense. It's merely the cheapest, easiest, and most foul way for evil to really grind it's victory into the reader's face. [Answer] The way you describe it, the city is floating, the height at which it does can be adjusted, but it doesn't seem like its position can. Like regular ground-based cities, yours will have some problems regarding food and water supply, possibly greater than what a ground-based city might have. How does the city supply itself? Eventually the people inside will have to get to the ground to get food and water; even if the farmland necessary for the city to sustain itself was floating, it would still need water, and its inhabitants would need it too. The best and safest way to capture such a city would be to surround it, capture its water/food supply and just wait. Humans tend to require water, else [bad stuff](https://en.wikipedia.org/wiki/Dehydration) happens. If you need your soldiers to infiltrate the city, you could set up a desperate run for food/water by the people inside, have them captured, and then send back up your men. [Answer] I think your best option lies with an elongated trebuchet. A normal trebuchet would look like this: ``` o-------------[] \| \| ``` It can shoot heavy stones to quite large distances, however, if you substitute the part left of the fulcrum by a much thinner, longer arm: ``` ··················----[] \| \| ``` You can esentially launch a much lighter projectile (such as a small harpoon tied to a thin rope) at several times the speed, achieving distances nearly an order of magnitude higher. [Answer] First, this city is impossible to assault. If a city is immune to siege engines due to being able to go higher, there is absolutely no way your army can climb up even if somebody can get some ropes up. Historically, the solution to assaulting the unassailable has been to make it assailable by building a pathway that can be used for assault. [Masada](https://en.wikipedia.org/wiki/Siege_of_Masada) and [Tyre](https://en.wikipedia.org/wiki/Siege_of_Tyre_(332_BC)) being the easy examples. [Persian conquest of Babylon](https://en.wikipedia.org/wiki/Babylon#Persian_conquest) by diverting the river is also nice. Your city seems immune to even that. But then again... The analogy would be to not assault it when its floating, but to first get it to come down and then attack it. The altitude of the city is controllable and presumably it can come down to ground or at least very close since the city can get supplied without flying vehicles. So how do you get it to come down? The first method is to use the Greek approach. "Beware of Greeks bearing gifts" was not really about the Trojan horse. It was about the annoying habit the Greeks had of conquering fortifications by simply bribing a commander to open the gates or let them over the wall. This could be easily adapted to your scenario. Get a messenger inside and promise to make a dozen men fed up with, let us be honest here, futile and suicidal resistance rich. You can even promise to spare the city atrocities and looting, the implication being that "If you refuse to become filthy rich there will be atrocities." The second method is assassination. A resistance such as this has one or two moral leaders. Remove those and negotiations for surrender will be imminent. At the very least the morale will collapse to the point where offers of bribes will become very attractive. I mean, those people were killed inside the "unassailable" city, so nobody will be feeling safe. Leaving a letter on the bedside table with dagger on top of it has sometimes been enough. Sometimes showing you could assassinate is better than actually doing it. So how do you get messengers or assassins in? Of solutions proposed in other answers, hot air balloons would probably work. More epic and less tech level busting solution would be to wait for strong wind and use large kites. The prosaic, boring, and practical solution is to simply get your agents into the city before the siege. I mean seriously, you have known you will want to conquer this city for years is there any reason not to be prepared in advance? Especially when it is obvious that getting into the city after the siege starts will be a major pain. You can either bribe necessary amount of soldiers in advance, there are no absolutely loyal troops with enough time to prepare, or infiltrate your assassins among the "invisible" servants or common soldiers. Probably both. But seriously a floating city with only loyal soldiers inside is pointless. A city is its people. A fully evacuated city can be simply ignored until the doomsday comes and hell freezes over. Or the defenders get bored of pointless resistance ignored by even their enemy. [Answer] It would probably be possible(ish) but I'd pick something else than a ballista for stage one. Use some siege weapon more adapted to hurling heavy payloads, like a trebuchet, for the first stage. Then make a projectile for the trebuchet of a fin-stabilized ballista with some sort of delay mechanism that triggers stage two... Ok, it's not really practical, but not impossible and follows the rule of cool. On second thought, you can use the trailed rope to stabilize the ballista and skip the fins. [Answer] Hmm. I might have several possibilities for you. But bear in mind that I'm kind of an organic writer (I love coming up with these things then shooting them down one by one, or bettering one or two until I come to either a proper conclusion, or know what just isn't happening). So let's agree on the limitations on which these possibilities will be based. * No gunpowder * No magic (or so little it might as well be none) * No Deus Ex Machina * No traitors or convenient serendipity * Low tech Right. So given you want a mechanical solution, let's see what this twisted mind of mine comes up with. 1. The glider option isn't impossible, but you're over complicating it. Your army is on open plains, but you are also looking at a literal army that needs to storm the gates. Getting everyone a glider is expensive. Getting all of them up in the air is nearly impossible. You need to take into account that some will have a fear of heights, or will be nervous and butterfinger-y, which could lead to them literally falling out of the sky. Given the era, safety regulations will be unheard of, so people will die on the climb regardless. So get into the meat of the theory behind gliders, set them upwind, and have them armed with crossbows with rope to make sure they can get into the city. This method guarantees heavy casualties, because it sounds like this city is heavily fortified. A castle-like structure. Heavy losses on the attackers' side is all but guaranteed, so it might be written off as acceptable losses. Still, the glider thing feels stilted, at best. 2. Why not go for the undercover route? I mean, this place is hovering, why not just use ballistas to attach ropes to the underbelly of the city and have your people dig up until they're in? You could have them attach the ropes in the dead of night, to ensure they aren't under constant arrow-fire. But this route assumes it's doable--very dependent on there being no handwavium or super dense adamantine flooring. 3. I've considered the balloon thing, but that's a slaughter waiting to happen. I mean, if the defenders have ballistas or bows and a plethora of arrows? Balloons aren't the most defensible places to stage an attack. What the attackers could do is have a portion of their army up in balloons with either ballistas or crossbow, or whatever, and rain down cover-fire on the defenders while their compatriots are scaling the walls. But this means knowing well in advance what the winds will be like, and so much hair-thin precision planning that it would take a genius (or plot armour) for it to work. It's not impossible, though. And if you have a character that's already shown themselves the tactician, this is the better route. Still, much room for error, and that isn't always something you want. And that's ignoring the ginormous material costs to this approach. 4. Sieges are about starving the enemy. You know they cannot leave without your notice, and they are essentially trapped. So make them miserable. It's boring as all hell, but why not smoke them out? I mean, you're in a plains. That means the wind is typically predictable, so you can plan for where the fire needs to be lit. There won't be any air purifiers on the defenders' side, and this would essentially kill them slowly (though less slowly than starvation). If you have a chemist on hand, or a woodsman, they might know of local flora that might add a poisonous substance to the smoke cloud. Then all you need to do is wait the little bastards out. 5. If taking this place is imperative, and you need to keep the place intact, then you need to get creative. Look at the people in the attacking army. Who has the skills needed to get this job done. Are there any that were once of the rogue-archtype? A thief, a pickpocket. Something, anything. These types tend to know how to get around in small groups. Get them what they need--a long rope to climb up, that glider to swoop in, parachutes made of silk to paratrooper their way in. Get them in and let them raise hell among the enemy troops. Start fires in the enemy food stores. Spread rumours about a black magician, or a necromancer that will raise their corpses to ravage their loved ones. That's all I can come up with. I need coffee (preferably a non-poisoned variant). [Answer] ## Use thermals to get your glider up to height. The dual glider approach is impractical because the launch mechanisms for flinging the second glider will necessitate a massive first glider, and an even more massive launch apparatus to get it up to a decent height. Instead, your siege engineers should focus on figuring out how to get your first glider high enough to harpoon the city on its own. A good way of doing this is to use thermals. Thermals are rising columns of air that gliders or birds can circle in to gain altitude. Modern glider pilots of all forms use these to prolong their flights. You can ground launch your glider, using some sort of ballista-like mechanical assist, and then use thermals to climb to a sufficient height before harpooning the city. If there aren't enough naturally occurring thermals in the area, your troops could build a large bonfire to create one artificially. [Answer] Dig a big hole under the Eastern half of the city. Pile the dirt up under the Western half. Pretty soon the height differential causes a list to starboard. Continue until the city capsizes or everyone falls off, whichever comes first. Or for something a bit more evil and less daft, how about burning the town to ash with an [Archimedes heat ray](https://en.wikipedia.org/wiki/Archimedes#Heat_ray)? Or if the city is near weapons range, firing [dead animals, beehives, and the severed heads of captured enemies](http://www.midi-france.info/medievalwarfare/121343_perriers.htm) at them (to spread disease and generally prove your evilness). [Answer] How do people normally get into the fortress city? The Empire will do that. A lot of castles protection was offered by inaccessibility, your city has this in spades, yet there are no historical examples that I know of of people firing ropes up the walls. Mostly they used siege ladders and siege towers. Most Castles that were assaulted by an army and taken by force had a traitor do the dirty work and let them in. Most of the time castles were besieged and lost that way, you have suggested that they send away all non combatants to preserve food stock, this is a good thing for them, and a valid tactic, but as this is not actually a castle but a nation-city is it reasonable? Could the empire not capture enough of the citizens and force a surrender that way? If you are looking for a mechanical solution then I think you will struggle, mainly with the idea that even if they somehow get a rope up to top of the walls, the attackers can climb this rope without any of the defenders simply unhooking it. [Answer] The other answers are excellent, so I just wanted to address the problems with your "firing a ballista from a glider" solution. You're neglecting [Newton's Third Law:](http://www.physicsclassroom.com/class/newtlaws/Lesson-4/Newton-s-Third-Law) > > For every action, there is an equal and opposite reaction. > > > There's a reason large siege engines were firmly secured to the ground and usually very heavy. If you want to toss a projectile one direction, you have to have something to push against. A glider is attached to nothing (more or less -- it's complicated), so unless the glider is very heavy much of the kinetic energy that you expect to drive the bolt forward will actually push the glider backward. It might still work, but you'd have to get fairly close to the city and the bolt will have much less momentum than you might expect. Ah, but you say, the ballista will fire upwards at an angle and not forward in the direction the glider is moving! Ah, well, you see in this case all of the opposite kinetic energy will be directed down into the (presumably) lightweight and fragile air frame of the glider. Not a pleasant ending for your hapless aeronauts. But, ok. Let's say you use balloons instead. You still have to factor the weight of the rope itself. Rope that someone can actually climb (without special tools) would have to be fairly thick -- think the 2" manila rope you find in gym classes. This rope is about 1 lb per foot, so if the city floats 500 feet above the ground (not particularly high), that's 500 lbs of rope. Not impossible, but not insignificant, and certainly not something you would attach to the end of a bolt. Instead you attach some kind of lightweight rope through the "eye" of the bolt (like a needle), doubling it so you can keep hold of the free end. Then you attach the lightweight rope to the heavier rope and pull it through until the heavy rope is near the edge of the city or wherever it's possible climb up to. There's still the problem of how to secure the rope, and whether the weight of the climbing rope (plus the climbers) wouldn't detach the bolt, but you get the idea. So what is the solution? Others have proposed various things, but I think infiltration is most obvious, especially if those in the floating city don't know about balloons and other ways to float non-magically. In the dead of night, send a few dozen guys up by balloon, with ropes, and have them attach the ropes at various points. Heavy rope? Not a problem if you also give your climbers [ascenders](https://www.youtube.com/watch?v=PKEtAM0qZTE) of some kind. Then you can use a much lighter weight rope. These can be fabricated out of anything, although of course if they're too flimsy they could be unreliable. [Answer] Problems with the multi-stage ballista 1. Structural stresses on the glider. The glider would be subject to a very hard acceleration during launch. In many ways, this situation is similar to catapult launching of aircraft which puts 3.6 Gs on the pilot and airframe. <https://www.faa.gov/pilots/safety/pilotsafetybrochures/media/Acceleration.pdf> 2. Energy spent lifting the second stage. While momentum transfer in ballistics does degrade as you approach the extremes of mass. I.e. something that launches a 1kg object at 10m/s can't inherently launch a 1g object at 10km/s, Overall, any energy you spend lifting that second ballista is not going towards lifting the final bolt. 3. Newton's 3rd law. Without the ability to meaningfully brace, the glider is going to absorb much more of the stored energy that what you would want. 4. It'll be an easy target This ballista would have to be very large, most likely constructed in place, within easy view of the besieged city, which can let gravity work for it. Possible Alternatives Building a raised launch platform or a ramp to the city such as the Roman siege of Masada. <http://www.biblicalarchaeology.org/daily/biblical-sites-places/biblical-archaeology-sites/the-masada-siege/> While this would be time consuming, and workers would be exposed to fire, you could eventually build up to the city, or simply raise your catapults high enough to hit the city. Your Empire could also target the displaced civilian population. Eventually the Empire will probably want to claim these neighboring states as well anyway. Attacking when they are forced to deal with large refugee populations, would be opportune. Once you have hundreds if not thousands of hostages you are easily in a position to demand the surrender of the city. A risky approach would be to seemingly abandon the siege, but leave a contingent camped directly underneath. This contingent would be nearly invisible to the city above them. Eventually, when a city's scout descends to look around, it might be possible to send a strike team up the same way, allowing the breach necessary. [Answer] or, stay with me here, or the gliders could just have a fuse that burns all the way to the main charge once these things should be at their highest point. Here are a couple of things that people literally always forget. 1. People have known how simple kinematics work for a very long time so any civilization with a level of technology around that of ancient Greece should be able to make easy calculations like this. 2. Gunpowder might not have been around for as long as kinematics has, but it's not new. There are a few scenarios that would make it possible for a civilization at the tech level of ancient Greece to get it from a more advanced civilization who simply over looked it. These two points bring me to the second part of my answer. Why not just mount the ballistas on a siege tower? Alexander the Great had siege towers. If I'm not mistaken - I didn't look this up so I probably am at least somewhat wrong about the following statement - the Romans had and used siege towers. Can a ballista hit this floating city if it fired from 60ft in the air? Double ballista sounds cool, but there are just better alternatives available using period correct technology. tl;dr ancient people are smart likely could have laid siege to such a city with their technology without double balista. ]
[Question] [ A city-state has developed in the middle of a (magical) desert which is subjected to a constant wind and always regenerating its sand. This wind is gale force, always blows in a straight line from east to west, and is of a constant, unfluctuating speed - how do you prevent erosion or burial by blown sand? My first instinct was to build a wall round the east side of the city, but would the overall maintenance of a solid wall-face be greater than minor, as-and-when repairs to unguarded outer houses? (Presuming both are paid for by the city, but shovelling sand out of the drive is a citizen's own responsibility.) The other solution I've considered is streamlined buildings which curve in the direction of the wind flow, though I assume this would put limitations on how tall buildings could be, which is inconvenient to preventing getting buried. The city is built with modern day materials and has a decent economy, so what would be the most economically and logistically sound way to defend against desert reclamation? [Answer] This seems very similar to the Stormlight Archives series. There is a large storm that always comes from one direction. Because of this, all towns across the entire world are built to withstand a very strong force coming from that direction. If you have a quick second, I'd read through the link below. Might be an interesting read, as it sounds kind of like what you're imagining in a way. <http://stormlightarchive.wikia.com/wiki/Highstorm>: > > Caravans that are forced to weather a highstorm in the open chain their wagons to nearby boulders and use them for protection. Settlements have more permanent solutions. The city of Kholinar is built inside a large stone formation known as the windblades, while the town of Hearthstone uses the breakwall for protection. > > > [Answer] A Wedge shaped wall, with the point facing the wind would both mitigate the difficulties, and provide a near limitless energy source with vents along the walls which could be opened and closed to harness the wind power. Expansion to the system/city would be as simple as extending the walls Don't streamline the individual buildings, streamline the wall. additional structures outside the wall could be built to capture/channel the wind for whatever purposes you need. Edited to add For easy maintenance, the vents should be angled towards the wind, and slightly recessed when closed to eliminate the possibility of being stuck open and/or clogged with sand. In the recessed and closed position, both the openings of the vents and the vents themselves could easily be cleaned without having to deal with the winds and another edit To control the force of the wind, flow can be controlled by going from a wide to a narrow to a wide channel, various "catches" can be set up to catch the sand. with stone jutting out to slow the sand and catch basins below it. [Answer] Antarctic bases have largely solved the snow drifting against buildings problem by raising the buildings on stilts so that the snow blows clear underneath them. You could use the same strategy with sand. It would be advantageous to shape the buildings to enhance the wind under them helping to blow the sand clear. This could lead to some interesting building shapes in your world. Edit-Erosion control. If you have ever been on a beach In a high wind you will appreciate that it is the bottom of your legs that are stinging and that is where the highest erosion is taking place. Simply because sand is heavy and it takes more energy to lift it higher. Perhaps the bottoms of the legs could be covered in a hardened metal or dragon scales. By minimizing the area exposed to the highest erosion you minimize the amount of maintenance. [Answer] You could also create a biodome large enough for a city. On the west side, you can have your entrance and exit doors for your dragons and people to come in and out of. This will allow you to keep the east side structurally sound as you don't have to worry about weak points with entrances/bad sealing. Being that it is a dome, you can insure that no wall of sand will take over the city (Winds of this force will create daily [haboobs](https://en.wikipedia.org/wiki/Haboob). Trust me not fun being someone who has lived in the middle east and currently lives in Arizona). This will allow for the city to stay dust free and sealed in. You will also have to consider the shape of the path the air will take. If you provide a path for the air to travel back down the other side (an airplane wing for example) you will create constant downward wind on the far side. This is great if you are trying to use the wind to help propel something forward but not so much when people will be coming in and out through the entrance. This means that the top will need to be flat with a slight curve up to push the wind out and away from the farside. So essentially if you are still following along, the east side of the dome will start with a point to initially break the wind that works up to a wider segment where the inhabitants will live. The dome continues at a steady incline from the point like an equal-lateral triangle with the point facing into the wind. From there you have your livable area where this triangle reaches it's max height (inside the triangle will feed off of @Richard U's idea of harnessing the wind by creating a powerplant to help maintain aerodynamics and energy). The main body will then be like a cylinder with pointed sides (rounded falls into the issue I described above) with the flat end on top and bottom and the pointed north and south ends to help keep the wind away from the west side. On the top of the cylinder on the west side, you can add in a slight incline to push the wind up and away from the west wall. There should be enough wind diversion that the west side of the dome doesn't particularly matter on the shape as the top, north, south, and east points are all diverting the wind up and out. To keep the city from being burried you can create a storm drain of sorts like we have with water, that the sand will roll off of the dome and into the drains that will then take the sand and run it through a processing system that will allow for the sand to be used within the city. Glass is one of the biggest uses for sand along with construction in terms of cement/fiberglass and so on. The excess sand can be easily dumped off into the west side side outside where the wind will take the excess sand and blow it AWAY from the dome keeping the dome clean. The other great thing about biodomes is that you can regulate the air temperature. You said this is a desert so it would be really hot. A dome will allow you to control temperature and could even have a system that allows you to open or close shading in the dome to block out the sun on extremely hot days. [Answer] I don't have an illustration, but [R Buckmaster Fuller](https://infogalactic.com/info/Buckminster_Fuller) was heavily into environmental buildings, and once published an idea where buildings (especially skyscrapers) would have wing like outer surfaces that were mounted on bearings, and this able to "turn into" the wind for streamlining and reduction of wind forces on the building. The downside to this idea is twofold: 1. You need space around each building for the airfoil surface to turn. While the bottom few floors might not have the streamlining structure, there still needs to be enough room around the upper floors to ensure the airfoil does not turn into another structure nearby. 2. There will also be a large tip vortex being shed from the ends of the airfoil structure, which will affect buildings downwind (especially taller buildings). A tip vortex being shed at street level will make walking or driving very difficult as well. So individual buildings would have issues with shedding vortexes and turbulence (even if, and especially if they are not aerodynamic in the first place). So there are three other options: 1. Go underground. Living in tunnels may not be very exciting, but at least you are out of the wind. You need to have protected entryways to break the wind, but once you get down into the foyer, then you are free of the wind. Tunnels are infinitely extendable as well. 2. Build one singular building. This is essentially an [Arcology](https://infogalactic.com/info/Arcology) So long as the outside is sealed from the wind, and the entryways are sheltered from the wind, then you can live in the same conditions as you would in a tunnel. The primary issue is building in the first place, and doing repairs and renovations, but building temporary covers over the affected areas is possible. 3. Building a dome over the city. While there is going to be difficulty during the building or inflation stage, once the dome is erected it provides a smooth aerodynamic surface to deflect the wind. [Answer] Having grown up in a rather snowy area (Buffalo NY), I immediately thought of Snow Fences. I'm surprised no one has mentioned it yet. If you are considered that snow is different that sand, consider what a [study](http://www.extension.iastate.edu/forestry/publications/PDF_files/SHRP-H-320.pdf) published by the Strategic Highway Research Program (SHRP) of National Research Council in 1991 explains on page 9 (emphasis added): > > Blowing snow particles resemble tiny grains of sand. Snow particles that are too heavy to be suspended in the air move by bouncing or intermittently jumping (saltating) along the surface. If they are too heavy to saltate, particles roll or creep along the surface, forming "snow waves," or "dunes." Snow fences restrain the wind, reducing wind speed. This reduces the force of the wind on the surface of the snow, allowing the creeping and saltating particles to come to rest. Some of these particles are deposited on the upwind side of the fence because of the reduced wind speed that occurs ahead of the barrier. Most of the snow deposit occurs on the downwind side of the porous snow fence. Further information on how drifts form is given on p. 23, "The Four Stages of Drift Growth." > > > On Page 24 we find this helpful diagram: [![Stages of Growth](https://i.stack.imgur.com/LNHLI.png)](https://i.stack.imgur.com/LNHLI.png) Note that a 50% porous fence is mentioned. As I understand it, a solid wall would actually be less effective. There is also information about setback, overlap, and extensions for oblique, staggered fences. [![Setback, overlap, and extensions for oblique, staggered fences](https://i.stack.imgur.com/hSrIt.png)](https://i.stack.imgur.com/hSrIt.png) It is also important to note that the fences should not necessarily be perpendicular to the wind direction: [![Herringbone fences](https://i.stack.imgur.com/YtWXU.png)](https://i.stack.imgur.com/YtWXU.png) There are also considerations like height and bottom gap (emphasis in original): > > Adding 6 in. (15 cm) to a 4-ft. (1.2-m) fence increases its capacity by 30%. A gap between the bottom of the fence and the ground increases the height and capacity of a snow fence. Partially or totally buried fences do not trap blowing snow effectively, are often damaged by snow settlement, and can develop abnormally long drifts. A bottom gap reduces snow deposition close to the fence. > > > Again, a fence would be more effective that a solid wall. I doubt a solid wall would be able to have a gap at the bottom, whereas that is rather easy with a fence. And much more than can be repeated here. But are they really effective? See pages 5 and 6: [![enter image description here](https://i.stack.imgur.com/tFQHl.png)](https://i.stack.imgur.com/tFQHl.png) [![enter image description here](https://i.stack.imgur.com/HmIH2.png)](https://i.stack.imgur.com/HmIH2.png) Note that I found the above reference among many more in the [References](https://en.wikipedia.org/wiki/Snow_fence#References) section of the Wikipedia article on Snow Fences (which also links to the much less complete [Sand Fence](https://en.wikipedia.org/wiki/Sand_fence) article with some additional references). [Answer] I see a couple possibilities: Build the Wall * The "wall" could be a long tall building making the construction efforts serve multiple purposes. * Look for local geography to help, find a series of hills and put your wall on top of them to increase height and strengthen the natural windbreaks. * If made from local materials you would want to quarry material from behind the wall either enlarging an existing valley or making an entirely artificial one for your city. * Redundancy is good here, a series of smaller walls ahead of your main city wall if properly spaced could aid in deflecting winds, and provide a suburb or otherwise section off the city. Dust First off if you have a "constant" gale force wind blowing in the same direction then I wouldn't expect a lot of dust, it would have blown away a long time ago, either leaving bed rock or forming fairly stable dunes. In terms of dust removal, you have a constant wind force being supplied to blow that dust away, a properly engineered and shaped wall would direct the wind to blow the dust to the sides away from the city with little accumulation on the wall. This would cause a series of dunes to develop on either side of the city. Or just let the dust pile up, you would end up with an artificial hill, which would still provide a wind break, the only downside would be the dust blowing over the top dropping into your city which would be annoying at times but not a deal breaker for a settlement. Other Options: Your city is likely to need water so why not dig a canal into your desert to provide it. The canal could provide water to support a large forest style windbreak. Using trees and forests as windbreaks is the most common historical windbreak method. A constant gale force wind would require a lot of effort to support growing a new forest (likely many small windbreaks to protect the seedlings, but once grown it would likely be self sustaining requiring little maintenance. [Answer] A series of low walls with cleared channels between them and a low rise city. You don't need to worry about streamlining the walls, it's perhaps better not to. Build up of sand on the outside of the wall will protect all but the top edge from erosion. Repairing the top edge will be part of your standard city maintenance process. The wind will accelerate over the top of the wall and pick up additional particles, this isn't ideal, but the sudden pressure drop and resultant drop in wind speed behind each wall will cause it to dump a percentage of its particle load. The higher the wall the greater the pressure drop, the greater the percentage of particles dropped from the wind. This will reduce the erosion on your city. What you're doing is creating a sand dune in a fixed location to shelter your city behind. You must keep clearing the channels between and behind the wall though or the ultimate demise of your city under your own ever growing artificial dune will become inevitable. You should also build your structures in such a way that when the sand builds up too much around the base of the buildings you can just tag an extra story on the top and abandon the lost levels to the sand. To summarise, what I would advise is one of the following: 1. Use tents or other temporary structures, rebuild on top of the encroaching sand on a regular basis. Don't pretend you can hold back the march of the desert, it will always win. 2. Build your city somewhere else, preferably somewhere with fresh water. [Answer] ## Magic solves everything. Since you have already established the presence of magic, I have a few suggestions; take your pick: * Use magic Walls of Force, which are not subject to erosion or wind strength. This could come from animals of some kind (probably a prey-type) which developed the ability as protection in the desert from the wind and sand, possibly even predators. There may also be minerals which when processed produce a force field of some kind(plane, sphere, some other shape). These could be used as building blocks in a wall, or at least as surface facing to reduce or eliminate wear and tear. * Use magic Walls of Stone, which would need occasional patching. A creature that could create it's own burrows would have a large survival advantage in a desert, or constant wind environment such as described. It would likely also have an ability to soften or destroy stone. Again, most likely to be a prey-type animal. A magical mineral, which when treated in some fashion, fed energy, heat, etc... expands and grows could also be used. * Use magic Walls of Fire, which would melt the incoming sand and heap up a huge glass structure that constantly rebuilds itself. Any creature which consistently produces fire could pull this off - a dragon or some creature which burrows through rock using heat to melt things. (most likely to be a predator, but prey is also a possibility.) melt enough sand to glass and you can eventually build up walls to protect the city. Again, should there be a magical mineral which produces enough heat to melt sand, then it could be used in furnaces to mass produce the glass needed to keep up the walls. * Use magic Walls of Water, which would mix with the sand, create mud, and get baked dry. So long as the walls are magically replenished, you also have a water supply - likely to be important. Also self-rebuilding. It is unlikely to find a creature in the desert which could produce enough water to maintain a wall, but producing water would be a definite survival advantage in general. Also, should enough of these creatures be domesticated or harvested, then using mud as building bricks is certainly a possibility. * Dig your city down deep, and use magic portals or a periscope-like extensible tower which can break through the current surface of the sand for those times you need to get in or out. Digging down deep could be accomplished by tech or creatures - portals however are usually the result of some kind of tech... unless you have something like link-stone. This unusual mineral has properties such that when you have a large enough chunk, and when split in half, each half remains connected to the other half, resulting in a portal-like opening that is connected to each other on the two halves. * Flying city which tacks back and forth across the wind to maintain roughly the same positional region. This is doable with tech and any handy animals that produce hydrogen or helium to fill your dirigibles. Or handy underground deposits. * Magical phasing creatures which can pass through the sand, bringing stuff with them, as mounts, cargo transport, and entry/exit methods. Probably an underground city again here. * Magical creatures which can dig through or melt through the sand to provide entry and egress - again, likely to be underground. (giant worms which produce a rare material, anyone?) * Use a magical mineral which repels wind or sand, thus allowing you to part the wind and/or sand around your city. Place it appropriately at the leading edge of your city. Animals with control over wind or sand, should that control be large enough may also be able to be trained for this. (Edited for conformity with the new information) [Answer] In [Yoko Tsuno : the 3 suns of Vinea](https://fr.wikipedia.org/wiki/Les_Trois_Soleils_de_Vin%C3%A9a) (french comic), there is a small city near an exhaust pipe of a wind factory. Their architecture look like trapezoidal houses build in the mountain to allow wind to pass by, regulate temperature and harvest wind energy with small turbines. [![enter image description here](https://i.stack.imgur.com/7219j.jpg)](https://i.stack.imgur.com/7219j.jpg) They harvest energy from the wind with big flying kites. [![enter image description here](https://i.stack.imgur.com/Pb3pF.jpg)](https://i.stack.imgur.com/Pb3pF.jpg) There is no concept of erosion in the comic but since it is an extra-terrestrial lifeform, they might have strong unknown material to manage this. Sand burial is managed by the fact that everything is on higher grounds. [Answer] This is not exactly the same as the conditions in Brandon Sanderson's The Stormlight Archive series, but the principle is similar enough: every few days a highstorm (a massive hurricane powered by magic that keeps it from immediately petering out when it makes landfall) blows across the continent, always from east to west. Cities are built in laits, which are natural shelters afforded on the leeward side of cliffs and other large rock formations. This provides a great deal of protection from highstorms, and it would likewise provide protection for your wind-land cities. The really tricky thing here isn't the cities, though; it's travel between them. If the wind never lets up, it's very difficult to safely go outside of sheltered areas! ]
[Question] [ I know things like bombing the major power plants and things like that could temporarily stop electricity production, but I'm talking about changing the way it works. Like we can no longer use any means of creating electricity. Not even solar. What would have to happen to render all of that inert? [Answer] The other answers have, I think, clearly demonstrated why it's a bad idea to mess with physics and make this literally impossible. It's not a user friendly system — you try to turn off electricity globally and all your humans drop dead, which makes for a tough story. Instead, what you should do is keep all the physics the same, but introduce some sort of outside effect that makes it impossible to use that electricity. Here's a few possibilities for this: 1. Grey Goo — nanotech designed to eat certain metals, destroying most of our ability to transmit electricity, and lots of our ability to generate it. A limiting factor would be that the goo needs active energy generation to power the replication/eating process, so if you have static metal it gets left alone. So swords/guns are ok, power lines are not. 2. Green Goo — same as above, but instead of mechanical nanotech, some sort of evolved super-lichen or mold. 3. Alien intervention — for some reason they're here and they don't want us making electricity. Anyone generating usable electrical power for more than a few seconds gets a rock to the head from space. 4. Magnetic/Solar interference — I am not 100% sure on this one, but I think that it's possible that if there was a ton of constant solar activity, or if the earth's magnetosphere went crazy, that most traditional electrical uses would be curtailed. This does allow for shielded (underground?) or hardened electrical use, but it would be very limited and the shelf life would be reduced — you'd see things like components burning out early, for example. [Answer] > > What would have to happen to render all of that inert? > > > Heat death of the universe? Seriously, electricity is just electrons moving along atoms. Preventing that would likely change the chemical properties of... everything. Something as elemental as fire would probably not work right since the oxidation involves sharing of electrons between the oxygen and whatever's burning (with energy release as a side effect). The heat death of the universe means there's no entropy difference to move the electrons, they just sit there. But it's also an exceptionally boring universe to write about. [Answer] You could achieve this in larger scales simply by making losses transmitting power much larger. For example if all metals became much worse at conducting. If you fine tune it correctly you would get no effects at micro scales (so chemical reactions and neurones would still work fine) but large effects at macro scales. This does mean that electronics (particularly simple electronics) would still work, however getting energy to them in order to power them would be extremely difficult. [Answer] Instead of trying to remove all electricity how about creating an environment which more or less severely hampers its use. For example, an electromagnetic pulse essentially fries all electronics that are not shielded. Perhaps the Earth's magnetic field has been modified to constantly generate EMPs. At first this was a surprise so 95% of electronics went down. Since the effect is now constant, things can be rebuilt but it will take a long time to do this and because it happened so quickly many people died and the number of people left have to worry mostly about basic survival. Small amounts of electric devices can still function if they are shielded(Faraday cage) but it really doesn't do much good for society in general. Since one working light that is run on batteries in a Faraday cage can only work in the Faraday cage and then there will be no more batteries. One could even say that the EMP bursts only occur once a week/month/etc. I could elaborate more but I think you get the idea. [Answer] As often is the case, Belgian comic books have done it before, in Jommeke 205: The copper microbes (Dutch title: De kopermicroben). ![enter image description here](https://i.stack.imgur.com/RuP9M.png) This album is basically a classic grey goo scenario devised by a mad scientist, but instead of the grey goo destroying the copper of the high voltage wires, it makes the copper non-conductive to electricity. for added effect, it's also reversible. In addition, it also means that anything that relies on electricity doesn't break (it all works again after the crisis is over), and that battery-operated items don't break. [Answer] Look up the Carrington event of 1859. From [Wikipedia](https://en.wikipedia.org/wiki/Solar_storm_of_1859): > > Telegraph systems all over Europe and North America failed, in some cases giving telegraph operators electric shocks. Telegraph pylons threw sparks. Some telegraph operators could continue to send and receive messages despite having disconnected their power supplies. > > > [Answer] Telastyn has the real answer, so I wanted to give a goofy one which meets the goals, but shows how tricky it's going to be to accomplish them, maybe with a wee bit of humor Give every electron one of [these](https://2.bp.blogspot.com/-SCeZNZp8n3M/UKmJfs3gphI/AAAAAAAAABQ/4Nd2gKuXkdY/s1600/monkey+backpack+.jpg): ![](https://2.bp.blogspot.com/-SCeZNZp8n3M/UKmJfs3gphI/AAAAAAAAABQ/4Nd2gKuXkdY/s1600/monkey+backpack+.jpg) The reason electricity flows is because the electrons are not 1:1 bound to specific protons. They're allowed to flow from atom to atom within metals. If each proton could give its electrons monkey backpacks (and not get the cords tangled), the electrons could go far enough to bond to make covalent molecules, but not metals or ionized gases. The only issue is that this is a classical solution. If you admit QM, you're going to have to worry about electrons quantum tunneling out of your monkey backpack (every parent's worst fear). There are also the issues of electrons thinking it's hillarious to tie their parents (I mean protons) in knots. --- In electrical engineering, we have this idea of a "[drift velocity](http://en.wikipedia.org/wiki/Drift_velocity)" to describe current. You can calculate the statistical drift of electrons through a wire. Wikipedia's example calculates that 3A through a particular thickness of wire yielded a drift velocity of -2.8 mm/s. Compare that against the Fermi velocity, which measures the rate that electrons bounce around at room temperature, of 1,570km/s (or 1,570,000,000 mm/s to keep the units the same between the two values). There's not actually all that much movement in electricity! [Answer] A Solar flare is the most likely scenario, but not the only way to put the Earth back into Dark Ages! A comet or meteor would also do just as nice. Scientists data prove that if one of these cataclysms were to happen, it would take at least 10-30 years to restore our infrastructure on our power grids. [Answer] [The Photonic Belt](https://en.wikipedia.org/wiki/Photon_belt) from outer space (known also as "Bond" Radiations, "Photon Belt", "Photonic Belt" or "Photonic Band"). It was discovered in 1961 as unusual nebula. We normally understand nebula as a vast cloud-like mass of gas or dust. However in 1980s an important announcement of astronomical and historical significance was made that our solar system was, going to collide with an 'electromagnetic cloud' in the not too distant future (it was named the Golden Nebula). Basically it's a huge torroid ("belt" of inter-dimensional light) which passes through our part of Milky Way in 26000-year cycle. Its intense electromagnetic radiation (the magnetic flow) throughout the visible spectrum and beyond, into high-frequency invisible light, including some x-ray spectra, can affect and interfere with our existing electromagnetic fields (devices) including solar panels (as they're not able to generate stable flow of electric charge, in other words [electromagnetic fields](https://en.wikipedia.org/wiki/Electromagnetic_field)). [![Photon Belt](https://i.stack.imgur.com/XqPLLl.jpg)](http://www.worldwidewaterplan.com/pleiades.htm) Sources: * [The Golden Nebula](http://www.bibliotecapleyades.net/universo/esp_cinturon_fotones_13.htm), * [The Pleiades and our own Photonic Belt](http://www.worldwidewaterplan.com/pleiades.htm) ]
[Question] [ This was my answer to this question: [Retrofitting geocentrism - what replaces the star?](https://worldbuilding.stackexchange.com/questions/237632/retrofitting-geocentrism-what-replaces-the-star) I spent long enough on it and got an interesting enough result that I wanted to share, so that it might be a useful resource for a storyteller one day. Especially because the question was not highly active and was already answered before I got to it. Please feel free to 1 Implicit in every answer) Point out any mathematical errors, etc. Please be charitable! 2 Actual on topic main question) Suggest how the burn rate of the moon might be made stable and sort of constant. I am not a physicist or anything like it, so there's a very good chance that there are insurmountable (as opposed to obvious, but fixable) problems with keeping this moon reacting in a stable and constant manner. Could a moon made of fissile uranium produce enough heat to replace the sun? As described; that's pretty unambiguous, isn't it? We want something in the sky that looks like the sun but is actually a moon. I hoped that the moon would have enough fuel to last a long time while heating the earth, be roughly the mass of the real moon, and a similar angular width in the sky, and result in an Earth with temperature roughly similar to real life Earth. PS I'm sorry for the formatting. [Answer] There are a few problems that would prevent that. One problem is that fusion and fission work differently. For fission you have neutron bullets flying around. When one causes fission, it pops off other bullets that can cause fission in other atoms. That's why you get chain reactions. Fusion is different, which is why it is so difficult to create fusion reactors that produce more energy than they require. You need high temperatures and pressures to force nuclei together. The sun gets that for free just by being so large. Even in the core of the sun with all that temperature and pressure, every cubic meter of the core only produces about 100w of energy. 15 cubic meters, like a small room that is 2.5 meters by 3 meters and 2 meters tall, only produces as much heat as a plug-in space heater. If the sun is fusing too much, the temperature goes up, the density decreases, and the reaction slows down. This is a self-regulating reaction that can last billions of years before the hydrogen fuel is used up. If the moon were made of uranium, it would be about 6 times as dense if it were a solid. In order to provide light like the sun, the outside would have to be the same temperature as the sun, that is what produces the light. Daylight is about 6500k. Uranium's boiling point at atmospheric pressure is 4091k. Tungsten, the element with the highest boiling point, is about 6000k. So to get light like the sun, the surface will have to be gaseous or plasma. Better to have a large surface that is non-reactive to dissipate the heat anyway, you don't want the gamma rays from the reactions directly raining down on the Earth. But for the heat to work it's way to the surface, the core that produces the heat would have to be even hotter. The pressure inside may be enough to keep the uranium liquid, but the outer layers would boil away and be lost to space, eventually exposing the core which would boil away as well without the pressure to keep it from doing so. The sun is 385 times as far away from the Earth as the moon, so for the moon to provide the earth with the same energy, it must only produce 1/148225th as much energy as the sun. The sun produces about 3.8e26 joules each second, so the moon would only need to produce about 2.5e21 joules each second. That's about 30 million kg or 15,000 tons of U-235 each second. The good news is that if you had a moon's volume of U-235 and could control the reaction, that could last a billion years. [Answer] The nominal spherical critical mass of untampered U235 is 56kg. This would form a sphere just over 17cm in diameter which is less than 3 litres. The volume of the Moon exceeds this volume by such a large margin that it's hard to know where to start. Such an astronomically vast quantity of fissile uranium could never be assembled in one place. Even a few litres would result in a very messy highly radioactive damp Squib reaction that would separate the materials and stop the reaction. If by some miracle the physics of radiation could be turned off for the Moon and such a quantity of fissile uranium was assembled in one place, as soon as physics was switched back on the Moon, the Earth and possibly the Sun as well would disappear nova style explosion. (~10^22 fission bombs). Could the fissile material be diluted? Yes it could at some point sufficient diluent could be added to prevent detonation, but that would seriously limit the amount of energy being released defeating the whole point. In any situation involving vast amounts of heat, uranium and diluent it is unlikely that the right balance of materials would remain for long due to phase changes, chemical reactions, convection currents and a multitude of other effects. [Answer] This is problematic. As others have mentioned, fissile U235 would explode and weakly radioactive U238 would get warm. Neither would make a good star. But there are non-fissile radioisotopes that would put out the right amount of energy if you had a moon-sized ball of them... So the problem would seem to be finding the isotope with the right half-life. However if this ball is giving out a sun-like amount of heat per square metre of the Earth, it is going to have to have a sun-like brightness, and that means a sun-like surface temperature (it will actually have greater density, so for the same mass it will be smaller than the moon, and have a smaller angular size than the moon or sun... so will have to be rather hotter than the sun) And if it is hotter than the sun on the surface, it will be made of plasma... and there isn't enough gravity to keep a 6000K plasma contained on the moon. So the moon expands and cools, without enough gravity to hold it together. It might cool enough to form a hot ring around the Earth for a while, but the atoms would be too hot to stay in orbit and it would gradually dissipate. The sun can only stay a hot ball of fire, because it has enough mass to hold itself together. If you had a hot ball of fire that was the size of a moon. no matter this ball of fire was heated, it would not hold itself together. It is really hard to make a small star to go around the Earth (without magic) Simply because anything hot enough to heat the Earth is to hot to remain in in one place. [Answer] Here goes. The moon has mass around 1 x10^23 kg, and radius 1.75 x10^6 m. Earth has radius 1.3 x10^7 m. At 3.84 x10^8 m distance, earth covers 0.0338 rad angular distance from the moon. (theta = arcsin (radius/distance)). This means it covers a fraction of 0.00564 of the moon's night sky (areafrac = 1-cos(pi x theta)). And the sky is only half the angular area that the moon would send radiation to. So for every watt received at the atmosphere of earth, the moon would have to emit 2 / arcfrac watts = 354.6 W. In real life we receive 1.73 x10^14 W of solar energy at the surface, with about 50% having been reflected into space. So earth received 3.46x10^14 W total. That means the moon would have to emit 354.6 x 3.46 x10^14 W = 1.227 x10^17 W, or 3.869 x10^24 J in a year. A kg of uranium emits about 8.2 x10^13 J/kg when fissioned. So the burn rate of uranium is 3.869 x10^24 / 8.2 x10^13 = 4.72 x10^10 kg per year. If this moon lasts 10^12 years, it has a mass of 9.44 x10^22 kg. This is pretty darned close to the real life mass of the moon. This means that this moon of pure uranium, density 19000 g/m^3, has volume 4.97 x10^18 m^3. That gives it a radius of 1.06 x10^6, about half that of the real moon (which makes sense, uranium is roughly 6 times denser than moon rock). In other words, the moon looks and acts very much like the moon does now, but it's a bit smaller and is as bright as the sun. Now, of course, that moon will explode (right, physics crowd? I'm only a chemist / programmer). But that's with it lasting 10^12 years. Shorten that lifespan by a factor of up to 1000 and substitute in inert moon rock. Now the moon lasts for a billion years. And it looks and acts just like the sun does now. This assumes that with some proportion of U-235 between pure and 1 in 1000, the moon becomes a stable nuclear pile. And that's where I use my hands; I either hand wave the problem away, or I hand away the problem to a physicist. Alternatively, the ratio could be even lower, but the life of the sun is then shorter. PS What the heck are gamma rays and xrays? You're making things up, nothing to see here, don't blame me if you're getting weird burns. [Answer] U-238 alone won't do the trick. To have relevant heat, you'll need to mix in U-235. ## Moon crust A moon crust will form, shielding the hot moon kernel from loosing any more heat. It will shine, but it won't last long. A U-moon will not consist of perfectly even distributed U-isotopes. Any presence of relevant amounts of U-235 in the mix will cause rocks on the surface to surpass critical mass.. and explode, the U-235 heat will be lost to space. Moon CRUST consisting of U-238 will form and the surface will cool down soon, the heat kept in the hot kernel. That heat cannot reach the planet. Can the kernel remain stable ? It could last for a few thousand years, but I wonder if a kernel of Uranium under a moon crust is sustainable. Explosions of local U-235 concentrations (U-235 pockets) inside could make the whole moon unstable. [Answer] Another problem: The moon covers almost exactly the same amount of sky that the sun does. For Earth to receive equivalent energy that means the replacement moon must be at the same temperature. That means that you have a ball of gaseous uranium. In one sense this might be a good thing--contraction increases the fission rate, causing it to heat and therefore expand. This could possibly permit a reasonably stable reaction rate rather than just a big boom. However, the only gas the moon can hold onto now is Xenon. Heat it to the temperature of the surface of the sun and you're going to have a lot of your uranium escaping into space. Not to mention everything else will escape even easier, anything that's limiting the reaction rate will be departing, your moon is basically pure uranium and if that's not stable you have no solution. [Answer] ## No, but a micro-quasar might work The bigger your uranium moon-sun gets, the more likely it is to go critical and become a uranium moon-bomb. You are just too many orders of magnitude off for this to work. Other answers already address this in enough detail... but there might be an alternative that could meet your goal. While blackholes formed by collapsing stars have to be massive, primordial black holes have been theorized to be able to be any mass what so ever. Now, imagine you have a tiny blackhole in near orbit of a rouge world like the Earth. Next imagine this rouge world is passing through a nebula with lots of radical dust and gasses to pick up as it goes. Many of these gases will just fall into the micro blackhole, but many of them will be trapped in an accretion disk near the moon's event horizon where fusion could occur at a much smaller scale than a star. Your "moon" might technically then look more like this, but the scattering of light in the nebula gasses and your planet's atmosphere would probably still make it look more like a generally round shaped, ball of light. This should be able to give you a more stable, small orbiting heat source than you would from a uranium moon. [![enter image description here](https://i.stack.imgur.com/U6lIY.png)](https://i.stack.imgur.com/U6lIY.png) [Answer] Make an artifical sun satelllite orbiting the flat planet which has giant fusion ppwoer genrators providing electricity to power giant lamb ps all aimred at the palne tinstad of wastefully radiating heat and light in all directions. If the sun satelite has the same size as the Sun and is at the same distance as the Sun it will probably have to have the same surface temperature as the Sun. But if it is the size and distance of the Moon, it might be able to heat up the planet sufficiently while being cooler than the surface of the Sun. So possibly you won't have too big problems keep the machinery in the sun satellite from melting, vaporizing, and failing. What is the diameter of your flat world? What kind of orbit will the sun satellite have to have to light and heat the whole surface of the planet with 24 hour day night cycles? Those factors will determine how much energy the sun satellite will have to emit to keep the flat world warm and lighted. Possibly there is a fleet of sun satellites which orbit the planet so that for part of the day several suns might be visible. And possibly a swarm of tinier satellites orbit the flat world and direct infra red radiation at it to help heat it. If none of the lifeforms can see those infra red frequencies and if the the distance to those satellites is great enough compared to their diameters they will be effective invisible to the lifeforms of that world. So perhaps you should not mention too many details about the artifical sun satellite(s) orbiting your flat world, to avoid making it seem impossible to work. And I guess such an artifical sun satellite or satellites built by a highly advanced civilization will violate a lot few physical laws than your flat world. [Answer] A single solid piece of fissile material tends to have runaway reactivity as its mass increases. Instead, cover the moon in many small, jacketed masses The Sun is in hydrostatic equilibrium ; its internal production of heat is balanced by its gravity. If it gets a little hotter, the volume increases a little, which reduces production of heat, which causes its volume to decrease, which increases production of heat, and so on until it runs out of its current fuel. Slam a comet into the Sun and its mass increases, and its heat production increases to the slightly larger volume of equilibrium. It's all held together by gravity. Fission in solid objects does NOT have the same equilibrium. If you put enough fissile material together in one place to produce visible light, the whole assembly also tends to expand very rapidly and then be still and silent over a wide area. This is also called a nuclear bomb. Nothing is holding it together except relatively feeble steel and concrete. If you have 20 kg of U-235 formed together in a half-sphere, it produces measurable heat and dangerous radiations, but no usable light. If you take another 20 kg of U-235 and touch them, significantly more heat and radiation are produced, but still no usable light. Put a total of 47 kg of U-235 into a solid sphere, and it produces a very large amount of heat and radiation, and some blue glow. It is now at critical mass. Adding any more will probably make it explode. The blue glow is bremsstrahlung radiation, and if you're touching the object, you're going to die soon. Distance helps, but it's not a very safe light to read by or run a society by. Nuclear power plants are difficult to build and run because the balance point must be maintained intentionally by running coolant past the hot solid fissile material, a dynamic balance which must be intelligently and diligently controlled, or it can fail in a variety of highly problematic ways. The Sun provides useful visible+infrared light because its frequencies are downshifted. Its core makes hard gamma photons by slamming hydrogen and helium together, and those photons bounce around for a very long time before escaping from the sun. On the way, atoms will sometimes emit the photon not as full-strength gamma, but as several partial-strength photons. Emerging from the surface of the sun is a mix of photon strengths, mostly in the visible spectrum. We don't have exactly the same thing available, but we can use another method of moderation - separate the fissile masses with something inert. One option is to put a moderator and insulator jacket over a lot of sub-critical masses, and somehow ensure that the masses never get any closer. You've probably seen the pictures of Plutonium wrapped in a graphite jacket glowing red hot. Let's coat a quadrillion of those graphite-jacketed in a cube of glass to prevent them from getting close, and cover Luna with them. Now Luna will glow a nice red, and no human can ever land there again. Note : a solid Luna-sized object of jacketed fissile masses will be hotter in the center, and tend to melt, and then the masses will gather together, and then it will be a bomb. Start with a lot of non-fissile, high-melting temp stuff in the middle. ]
[Question] [ Robots in fiction, autonomous or self-aware, need ways to operate in mundane conditions otherwise they will eventually (without upkeep) fall to pieces. This includes events where one gets splashed with mud or any situation which entails getting dirty. Be it grime, muck or dirt any robot with actuated joints will need a way of staying clean, otherwise it loses functionality and goes straight to the scrapyard. Ideally the robot should be able to clean itself without outside help otherwise it won't last very long. > > -Will you be all right, Andrew? > > > -One is capable of > > > self-mai-ai-aintenance, sir. > > > -Good. > > > In this scenario the robot doesn't come pre-equipped with cleaning tools and will have to make use of any tools available. The settings include post apocalyptic cities and forests or any natural biome, neither of which have humans that could help. Coming across other robots that could help is a rare occurrence but by principle the robot should be independent. Its limbs include at least a pair of articulated arms with clampers or fingers. Robots can come in any number of shapes and sizes, but as long as they have two limbs and can reach all parts of their body they should be all right. How does a robot keep itself clean using available tools? This is one of those things in fiction you don't see much so getting an explanation would add little titbits of realism. As always creative answers are welcome and would be very helpful. [Answer] This is something that is already dealt with fairly extensively in the machining industry: You have cutting tools that generate lots of tiny metal chips immediately adjacent to bearings that need to be kept extremely clean to maintain their precision. It's been solved by using tight seals (like a [labyrinth seal](https://en.wikipedia.org/wiki/Labyrinth_seal) at all the moving interfaces, and pressurizing the internals of the bearings with clean, dry air. The air continuously leaks out through the seals, and prevents contaminants for getting in. This has the added benefit of also providing some active cooling (you are effectively blowing air through the thing), as well as being a way to deliver lubricant (if needed). It is not uncommon to use oil-mist carried by the air to lubricate the protected bearings as well as keep contamination out. The major downside of this approach is that it requires a continuous supply of compressed air or whatever purge fluid you're using. There is also some power required to provide the purge air. It also generally results in some continuous noise. Realistically, grease filled bellows (as in @KeizerHarm's answer) are probably a much better option. That approach is used by millions of cars on the road every day (see: [CV Joint Boots](https://www.google.com/search?q=cv%20joint%20boot)) in wet and dirty conditions under the vehicle. They do require periodic replacement, but it could be done one-at-a-time. --- It's worth noting that there are basically 2 regimes of sealing: * Sealing of a joint that is intended to allow continuous rotation. * Sealing of a joint that only allows limited rotation. Sealing while allowing continuous rotation is a lot more challenging, because you have to allow the rotation section to slide over the stationary side, it cannot be accomplished with compliant materials. Various industries have taken a lot of different approaches here, but the general consensus is that basically all the solutions wind up having some sort of wear component. For limited rotation, things like rubber bellows or other flexible materials can be used, since there isn't a need for the sliding contact. [Answer] Joints are wrapped in rubber: [![expansion joint](https://i.stack.imgur.com/trvHi.png)](https://i.stack.imgur.com/trvHi.png) Cleaned with water: [![watering](https://i.stack.imgur.com/Kt9ZD.jpg)](https://i.stack.imgur.com/Kt9ZD.jpg) Only opposable fingers and a source of water are needed. Compressed air or a simple brush for dry dirt may also suffice. [Answer] They wear clothes. Their joints are of course environmentally sealed with bellows, elastomer seals, etc, but to further protect these relatively-fragile components from damage, they use cloth coverings, which can easily be changed for fresh ones and cleaned separately from the robot. Plus, pockets are useful, and tool harnesses and such are easier to customize and change than the core chassis. [Answer] The joints are designed in such a way that doesn't allow dirt from the outside in. For example using something like [this](https://www.grommetseal.com/expansion-bellow/rubber-bellow/neoprene-bellow.html) > > Neoprene Bellow also known as Chloroprene Rubber Expansion Joint, neoprene dust boots, CR bellows and molded rubber bellows. The main function of neoprene rubber bellow is machinery seal, dust-proof, noise reduction, absorption of vibration and electrical insulation. > > > If dirt doesn't get it in, you don't need to clean it. And some compressed air can wipe out the dust from the surface. [Answer] # They shower They have arms and can reach anywhere in their bodies. Now all they need is access to some clean water, fine oils, polish, wax, a bucket, a piece of cloth and a sponge. If they drink Energon, some additives go a long way in clearing those pipes. Remember to avoid the leaded stuff. Galvanic anodes will protect against undesired pregnancies, but must be used in tabdem with an up-to-date anti-malware to properly prevent the spread of STD's. [Answer] > > otherwise it loses functionality and goes straight to the scrapyard. > > > Throw away a whole robot because a limb joint is seizing up? What an astonishingly wasteful thing to do. With a meatbag, of course, when a limb loses functionality it is basically written off, and the meatbag remains partially functional until death. When a robot limb becomes non-functional, there are more options. Firstly, robots are manufactured, not grown. Spare parts are available for mass-produced models, and less common ones at the very least get schematics and CAD diagrams. Hard-to-find parts can be removed from their owner, given a highly accurate 3D imaging and material scan and a suitable replacement can be procured via some appropriate means, ranging from molecular holography to blacksmithing or even carpentry, depending on the local technological capabilities and the particular requirements of the part. Non-functional examples of the same model (or at least other devices which share some common sub-assemblies) can be broken down for useful parts. But replacement isn't even necessarily indicated. A seized part can be removed and dismantled, cleaned and re-lubricated and finally re-installed. Documentation for appropriate lubricants and protective sealants will be readily available, probably even included in the robot's own firmware. Mechanical and chemical properties may also be documented so alternatives can be obtained in less civilized locales where field-expedient repairs take priority over following precise maintenance instructions according to the robots' warranty. > > How does a robot keep itself clean using available tools? > > > That rather depends on the nature of the robot now, doesn't it? Some robots might be built in such a way that they don't really have a notion of "dirty", and can operate indefinitely in hostile environments such as vacuum-exposed sharp ultrafine regolith or your meatbag digestive tracts. They may be subject to problems caused by violent mechanical trauma, but being assaulted or suffering damage from unexpected environments (like the inside of a collapsing building) is not really getting "dirty" and so is outside of the remit of this question. All robots will have specific environmental tolerances, and with some it just might not be possible to keep them going for days in a vast gritty swamp after a volcanic eruption or something, any more than a naked human is suitable for a trek over high mountain pass above the snowline. A robot intended for use in a generally hostile environment such as a planetary surface covered in abrasives and surrounded by an atmospheric of corrosive gasses such as oxygen and oceans of conductive liquids will be suitably sealed against the environment and will probably be cleanable by being sprayed down with water. Intrusions of water and grit and gas into the delicate interior can be dealt with by dismantling and cleaning and re-assembling as per the documentation, when a suitably clean environment is reached. If that seems unreasonable, then consider how partially dismantling humans for repair demands sterile conditions or they just up and die of infection, rather than just make nasty grinding noises and move at quarter speed for the next week. [Answer] A swim. [![enter image description here](https://i.stack.imgur.com/dn8Eel.jpg)](https://i.stack.imgur.com/dn8Eel.jpg) <https://www.goodfon.com/wallpaper/cyborg-forest-trees-river-waterfall-water-landscape-fantasy.html> In this empty world there are many lonely places a robot can take a swim. Accumulated dirt and sand is washed away. It is nice. This particular place also has good acoustics for robots that know how to sing. [Answer] Opening: "In this scenario the robot doesn't come pre-equipped with cleaning tools and will have to make use of any tools available. The settings include post apocalyptic cities and forests or any natural biome, neither of which have humans that could help" I can't really connect this to the "post apocalyptic" aspect but let's give a RW example, below scenario is quite recent technology of self-cleaning robots using external means. Robots clean themselves in the docking station Moving robots have a home spot, a docking station where the robot goes into maintenance mode and reloads its batteries. Humans or other robots can do small maintenance on the spot, or connect to the robot to refresh new neural network retraining, for the robot to learn new procedures, new routes, or recognize new objects. Built into the docking station, there are automatic means to clean the robot. It involves specialized parts of the docking station, handling brushes, water, sprays, hot air to dry.. These tools are at fixed locations in the docking station. While connected, the robot moves its parts in place for each cleaning stage. Cleaning tools may hold toxic substances and (in hospitals) a desinfection procedure. The robot will only switch cleaning devices on, when there are no humans near. There are sensors for that, no safety buttons needed. When no maintenance by humans is required, the docking station can perform battery loading and cleaning in ca. 20 minutes. Periodic cleaning and desinfection of robots is vital in hospitals, where robots can be assigned to perform tasks in different departments. Suppose your robot serves dinner to patients. You don't want your robot to move around with food remains spilled on it, spreading infectious disease across hospital departments. [Answer] Outside the Box The Robot is a golem- or simulacrum that is manufactured from a mineral-based mixture that includes minerals, organic matter, water and air. While these percentages are only generalizations at best, the typical robot consists of at least approximately 45% mineral, and 5% organic matter, suspended in a matrix of air and water. And the composition of the robot’s structure can fluctuate on a daily basis, depending on numerous factors such as water supply, cultivation practices, and/or material type. The mineral matter are in the form of grains having a variety of different chemical elements in their make-up, including Oxygen, Silicon, Aluminum, Iron, Calcium, and Sodium. The organic matter is comprised primarily of decayed carbon-based life forms. In short, the robot is dirt. More dirt can maintain them or increase their size or mass, or allow new capabilities. ]
[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 5 years ago. [Improve this question](/posts/115885/edit) I'm writing a MG novel (MG is aimed at a core audience of Middle Grade readers aged 8 to 12) set in Northern England, but I don't live there, so I'm not familiar with the local sense of propriety. In the scene I'm working on, two kids from a small (500 inhabitants), rural village decide to go for a swim in a nearby lake. It is a common place for the locals to go swimming, so kids walking there to swim is a common view. The kids are at the home of the 12-year-old girl, when they decide to go swimming. For practical reasons, the girl changes into her swimsuit, and then they walk to the boy's home where he changes into his swimming trunks. Then both kids walk through the village in their swimwear and over a path through the fields to the lake. I'm a bit unsure about this. Where I live, when I was small, it was quite common for kids to run around in bathing suits when it was hot in summer, but this has changed and I don't see kids in swimsuits in town any longer, except for toddlers playing in the fountain on the market place. Older kids aren't as carefree today as we were, and they dress properly on their way to the public pool. But how is that in England (today)? Would an English reader reading my book think that that's not how English kids would behave? Or would they find it completely normal? [Answer] In the summer, in a coastal town or a small town with a known outdoor swimming location such as a waterfall, river or other suitable pond, nobody would really think twice about it. If such features were not available then people might look askance. It doesn't work the same way for swimming pools. Basically it's normal if it's normal. If there's somewhere the kids swim then it would be as reasonable to walk to the location in swimming kit and flip-flops as to change at said location. Though your character is probably at an age where she's becoming self-conscious about this so it's as much about the psychology of teenagers as appropriate dress codes. [Answer] As an Englishman reading your extract, I can say that the impression I got was that the children must live in the countryside. Probably in a small town, where most of the people know each other. A place where children could go somewhere unsupervised wearing something that would likely make parents feel very worried were they living, say, in a city or town. Re-reading the question I see that that's exactly where you've set it! I might still expect that they would wear their swimwear underneath their clothes, or just swim in their clothes. Having them walk through the town in swimwear would give the impression of innocence on their part, a feeling that they lived in a rural idyll, and/or a feeling of unease and concern depending on the tone of the rest of the world around them. A cursory google for evidence of whether this impression is grounded in truth or not has produced a veritable mountain of dross 'debating' whether overprotective parenting is harming the next generation. If I find something that's actually worth something academically I'll include it! [Answer] In my experience, my comfort wearing a swimsuit changes on a street-by-street basis. So the particular route through the village matters. A street with grass and trees and buildings loosely packed feels fine: [![enter image description here](https://i.stack.imgur.com/aycWp.jpg)](https://i.stack.imgur.com/aycWp.jpg) While a street with shops up against the sidewalk and no greenery feels very off: [![enter image description here](https://i.stack.imgur.com/gHGDd.jpg)](https://i.stack.imgur.com/gHGDd.jpg) If I was in a swimsuit I'd feel compelled to avoid the street in that second image even if it meant taking a longer detour to stay on streets more like the first. I had not really put this instinct into actual rules before I thought about this question, but I'm quite sure I had this instinct by age 12. Around age 10 is when I started noticing such things so if the boy is younger than that he won't care. So it's plausible as long as they take streets that feel, I suppose you could say "relaxed", "country" or "homely" and avoid streets that are "downtown" or narrow, busy, or commercial zoned. If I'm reading about your character walking down the first street, all it tells me is she lives in a comfortable village and is a reasonably carefree child. If your character walked down a street like the second image in her swimsuit and didn't feel uncomfortable, she's either tone-deaf to a degree that seems concerning, or positively batty. [Answer] I don't know about northern England. When I was a child my family used to walk in our bathing suits three blocks to the beach in Cape May, New Jersey, USA which is a town with a permanent population of thousands and many summer visitors. But we would wear normal clothes to walk to the library or the shopping area. But that is thousands of miles and decades away from your setting. ]
[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/75497/edit). Closed 6 years ago. [Improve this question](/posts/75497/edit) In my story, some people have the power of teleportation. I have constructed it in a way in which for teleportation to occur, it needs to be a water surface. All one needs to do is to see the reflection of the place they are attempting to reach in the water's surface and jump in. The water is acting as a sort of portal. I want this to be an original thing, but knowing rules that have been used in the past would give me something to work with. I will construct my own limits for the sake of originality. My question is, what guidelines can be put in place to restrict teleporters from simply teleporting anywhere without limit? I don't want them to require an item in order to teleport. They already need a water surface in order to teleport. Is there any other guidelines that has been used in the past to restrict teleportation that would make sense in this scenario? Original ideas would also be welcomed. Thank you for the help. [Answer] A logical limitation would be that the further you travel, the more energy (mana) would be required, this would not only limit distance but also the amount of times you could teleport. For something more unique, where the limitation is not on the traveler, but on the pools of water, I think it would be cool that you could only teleport between places that have some sort of connection, physical or even conceptual. Some ideas: * Lakes fed by the same river. * Sun needs to touch the surface for it to be accessible. * There needs to be the same magic circle drawn around the water. * The water needs to be dyed the same color. * Indoors, at a church or temple. * Heated to some arbitrary temperature. * Additives to the water (e.g. Salt or minerals like in ocean water) That way you could have very generic "teleportation pools" that allow travel to all other capitals as public travel gates, as well as unique pairs for private, secure or secret purposes. As for the mechanisms, I see two nice options. 1. If pools are made to be the same, they literally become the same place, similar to a pocket dimension, so it's up to the travel from where they enter or exit. Maybe it's a natural phenomen or a wizard is involved. 2. Once a traveler enters the water, their soul leaves the body in search for similar pools and once it has found one, pulls the body along. Of course it's impossible to make the pools exactly the same, so the more differences there are between pools, the harder it is to travel between them. So more skilled travelers could ignore some but not all of the differences - maybe easier if he knows the exact differences. It would also open up interesting opportunities for someone to steal plans for a pool into the royal treasure chamber and fake it for a heist. [Answer] Classic teleportation limitations: * Had to have been there before. * Talent or power has an impact. Not everyone can teleport across the world. Create a radius according to ability. Difficulty can relate to both distance and familiarity with the locale. Only 1% of all teleporters can teleport to the other side of the world. * Teleporting takes energy. Only so many times a day or so much distance in a day. Less classic, more original--ingestion... * Teleporters need a certain thing in their bloodstream in order to power the teleportation. It doesn't need to be a drug, it could be something as simple as a certain spice or hot peppers or something. The difficulty of attaining it can be up to you. * Your teleporters actually have to have a vial of water from the location they intend to teleport to. If they have had a drink from it within a certain period of time (day, month, week, year) they can make the connection. You can also do a combo platter. * Perhaps there's natural ability concerning distance, but that can be augmented by ingesting the water from the locale. [Answer] In [The Stars My Destination](https://en.wikipedia.org/wiki/The_Stars_My_Destination), Alfred Bester used ubiquitous teleportation, called 'jaunting', which everyone could learn through some effort. To jaunte, you had to know where the starting and ending points were by seeing both in person. So you couldn't teleport from a room you entered in total darkness (the prisons had no lights) you couldn't teleport into a place that had moved since you last saw it (extremely secure rooms were on rails) and and you couldn't teleport to a place you'd never seen (so for the first trip you needed to hitch a ride, or go line of sight.) Perhaps not entirely comprehensive rules, but maybe a good place to start? Bester also limited teleportation to the speed of light, and his characters couldn't teleport through outer space... sort of. He never really infodumps how the jaunting works, but I think that's the gist of it. Anyways, I recommend reading the book if you have the chance, it's very well done. [Answer] Depending on how hard you want to make things - and what kind of weaknesses you want to allow - I can think of some ideas: * Both the target area and the pool of water to be used need to be flat, i.e. no teleporting to an wavy ocean or an area with rain, unless there is a prepared node to be used in the target location. * The teleporter creates the portal by astral projection of sorts: they have to astrally travel to where they're going (which obviously needs to be orders of magnitude faster than normal travel, possibly near-instantaneous). This means that they need to know where they're going, but not necessarily have been there before. Once they've created the "other end" of the portal and return from the projection, they see the other side on the reflection in the water. * Teleportation requires time and effort, making excessive use for shorter distances counter-productive. * Weight / amount / whatever constrained by physical/mental capabilities of the user. * Use of teleportation is risky, either due hostile forces trying to prevent travel and/or attacking travelers / teleporter or possibly due to the corrupting / corrupt nature of the forces used in the process. * Teleportation has a non-item cost, like reducing lifespan, burning a lot of calories, pretty much any weird / fantastic cost that can be paid by the teleporter himself. For humors sake, imagine a massively overweight mage summoned by the king to transport his army to relieve an allied force, with the mage emerging from the other side looking malnourished and skeletal from the effort. [Answer] If you want a more scientific limitation, say that teleportation preserves momentum, so if you teleport very far in any direction (on a spherical rotating planet) you end up moving too rapidly to survive. [Answer] Regarding specifically the use of a reflection for teleportation, in Leaper by Geoffrey Wood, <https://books.google.com/books/about/Leaper.html?id=ja4QOQAACAAJ&hl=en> the main character James teleports to locations known to him as he concentatrates on them sometimes with the aid of the reflection in his watch or a window. He gradually learns that clearly visualizing his intended destination, such as when he can see it in a reflection, helps him control the leaping experience. This story includes his deduction that it is a divine gift that only works when he is attempting to do good, and he envisions that this is a super-power gifted to him by God. I happen to be currently only half way through reading this book, so I don't know if there are any other rules involved yet to be explained, but thought it was quite similar to your proposed idea. The whole story so far explores the character's discovery of and examination of the purpose and mechanics of his new superpower. The author also alludes to use of meditative practices to encourage the calming of the noisy mind to better concentrate to facilitate use of the teleportation power, albeit from the nicely sarcastic viewpoint of the caffeine-addicted James character. Hope this is helpful. [Answer] You mentioned in a comment that one would need to visualize their destination in order to get there; as a start, I recommend limiting teleportation to places that the person had previously seen. You don't mention the technology level, but if televisions exist you need to make a judgment call on whether seeing a picture or live stream of a place counts as seeing it. There will also (obviously) be a limitation of your particular teleportation system, in that teleporters will have difficulty traveling to landlocked locations. [Answer] The water idea is interesting. The wrinkle I'd add would be that aim is tricky, and takes an unbelievable amount of concentration. So the further away the two locations, the larger the body of water required at the destination. So for somewhere nearby, perhaps a bathtub is sufficient. But the other side of the planet for all but the most skilled would probably require an ocean. [Answer] Two easy limits would be: * Require water to be present at the exit. * Require size of the mass of water both at the entrance and exit of the teleportation to be in proportion to the size of whatever is to be teleported [Answer] As you are using water as a medium for teleportation, you may think something like using water flow. Something like you can't go up a waterfall, only follow the flow of water [Answer] The teleporter has to visualize the place he wants to go in his head. The better he is able to do this the more accurate the teleportation. This means they need to have seen that place before. Unskilled teleporters may teleport to somewhere not that close to where they wanted to go while skilled teleporters may be able to teleport to places they have only seen on pictures. ]
[Question] [ Year 2020. Planet Earth is peacefully turning around the sun. Humans on planet earth, however, do not feel peaceful at all. Alien spaceships are in the sky. They did not answer, or humans could not find a way to communicate properly. The ships came near earth, stopped, waited a little, went back. Then, after a few weeks, they did it again. (And again, if needed) In fact, they look like they are scouting. It is pretty sure they are going to attack some day. The spaceships are quite small, they might be waiting for bigger ones. The spaceships do not last for long near Earth, then all we know about them is a visual aspect, perhaps the kind of metal or the weight of the spaceships (I think these can be calculated or observed with telescopes, comment if you think i am wrong or we can learn much more) What do we do to defend ourselves ? We don't even know against what we will have to fight ! As the question is very broad, here are a few assumptions to narrow it : * Humans chose to stop fighting themselves and cooperate in order to defend Earth (Big assumption) * Even if the aliens did not attack yet, scientists and militaries agrees their tactics look like scouting before an attack. I do not ask about politics or peace attempts that will certainly occur in the same time. They are here, now, and we have to prepare a possible war, in the worst case. * Alien spaceships did not come in the atmosphere. In a very large orbit, at best. * As long as there is no attack, defenses can be improved. Both short terms and long terms plans are available answers. Bonus : We have no idea what kind of creature/robot/life form is in the spaceships, our defense have to take that in consideration as they might not be organics. [Answer] Know thine enemy then plan from there. A great deal can be learned about the aliens and their craft, even without being able to talk to them. Listed below are a few parameters to analyze (I'm going to assume a [science-based](/questions/tagged/science-based "show questions tagged 'science-based'") for this question because it helps provide structure.) ## Information Gathering Propulsion Systems of the aliens Since the OP says the aliens just appeared in the sky, that means they have coasted into orbit from a long way off. Chemical rocket heat signatures can be seen from great distances and torchships can be seen from even farther away. Whatever they're doing, they took their sweet time doing it. Someone would have noticed a fast moving bright star against the cold of the cosmic background. From [Project Rho](http://www.projectrho.com/public_html/rocket/spacewardetect.php): > > If the spacecraft are torchships, their thrust power is several terawatts. This means the exhaust is so intense that it could be detected from Alpha Centauri. By a passive sensor...The Space Shuttle's much weaker main engines could be detected past the orbit of Pluto. > > > If they are using torchships, then passive defenses won't work since they can just burn through them with their exhaust. (Attacks on the torchships must be careful because the exhaust will burn projectiles too. Nuking the propulsion end of the ship won't do anything because th ship is nuking itself.) Further, torchships means that building bunkers for billions of humans will be a waste (and likely logistically impossible anyway). Or, they found a "reactionless" propulsion system such as the [Alcubierre Drive](https://en.wikipedia.org/wiki/Alcubierre_drive). If this is the case then the alien's understanding of physics far outstrips our own. While we may not be able to directly observe ships using an Alcubierre drive, we may be able to see any lensing effects on the star background when they engage the drive. Capturing such a ship would radically enhance our understanding of fundamental physics. Temperature of the ships We can learn a lot about the physical nature of the aliens based on how hot their ships are. If they are about 300K, we know they have biology approximating our own, or at least like living conditions similar to our own. Shape of the ships We know what aerodynamic ships look like, so we would be able to tell if the alien ships are intended to fly in an atmosphere. While this information in and of itself may not be incredibly useful, it is a valuable datapoint with regards to what the ships were designed for. Repurposing Hubble to take pictures of the ships shouldn't be too hard. Size of the Ships Larger ships are just harder to build. By determining the size of the ships, we can start making guesses about what kind of material sciences they have developed. A ship a kilometer long is far harder to strengthen and support than a ship a mere 100 meters long. Ship Emmissions If the ships are talking to each other over radio, visible light or laser, we should be able to pick that up. Like the shape of the space ships, what kind of radiation these ships emit could tell us something about the occupants. This might tell us why they aren't answering. Maybe. ## Active Defenses Beam Weapons - Dump as much money as possible into beam weapons. The US Navy in 2015 has some powerful ones capable of shooting down drones and missiles. BY 2020, they will likely have stronger ones. They may not be persuaded to share how they got such powerful beam weapons but they may be enticed to deploy such weapons all over the world. Large beam weapon installations could be spread across the planet to cover all approaches. Nuclear Shaped Charges - Some really crazy things can be done with [nuclear charges](http://www.projectrho.com/public_html/rocket/spacegunconvent.php#id--Nukes_In_Space--Nuclear_Shaped_Charges), especially ones that focus the energy of the nuke into a narrow beam. A barrage of these charges sent into space might destroy the entire scouting force. [Answer] In 2020, humanity would be very much like as it is today, since that is only 5 years in future. # 1. How our world would NOT be? * There would be no giant robots and flying cars running around our cities. * There would be no nanobots fabricating graphene-based complex nano-machines in industrial scale. * There would be no cyborgs with broad-band telepathic quantum-digital communication. * Genetic engineered mutants will not be warring to displace humans. * There would be no AI-based coordinated and efficient all-Earth government. * There would be no superintelligent beach crabs who calls Earth their homeworld projecting and building a Dyson sphere or a Death star. # 2. How our world would be? * The western world will be fighting jihadists in Middle East. UN will be paralyzed and ineffective due to Russia's and China's successive vetos to anything that could have some real effect in practice. * People will be talking about global warming. People who earn money by burning or selling fossil fuels will deny it. * There will be some people dying from malaria in some poor and disorganized countries. * There will be some tensions and hostilities between Israel and Palestine. * Obama's successor will be thinking about something to do with Cuba (not something military). Specially if he/she happens to be from the republican party. * Apple would be announcing their new iPhone 8. * Facebook will be launching some new services to compete with Google Alphabet. * Microsoft would be receiving a lot of complaints about their new and buggy Windows 12 and would be preparing a large patch called Windows 12.1. Bing's social-cloud-network integration in the OS raises a lot of complaints about privacy and anti-trust commercial practices, but it will reveal to be a very useful feature to allow botnets to download and install malwares in user's PCs. * NSA will be illegally tracking and monitoring your traffic in porn suspicious sites in order to find for interesting nudity criminal evidence. * Thanks to many technological breakthroughs, solar and eolic energy are indeed the future and they are very cheap in 2020 - long life to our green energy! But instead, governments and corporations would still prefer to burn oil to keep the money in the hands that it always used to be. Screw up those nasty green ecoterrorists and their stupid solar and eolic technologies! # 3. What would happen when the aliens arrive in 2020? 1. People will suspect that the thing is some sort of secret spacecraft developed in Area 51. US government will (as always) deny. Nobody will initially take US's deny seriously. And this is very ironic, since for tens of years, people who had seen secret airplanes/spacecraft tought that they were alien starships. Now that they are seeing actual alien starships, they will think that they are secret airplanes/spacecraft. 2. North Korea's government will tell their people that it is a North Korean spacecraft proposed and built by Kim Jong-Un himself and that this proves that North Korea has a tech level much more advanced than the rest of the world. 3. Islamic fundamentalists will say that the UFO is a sign of Allah's power. Some Christians and Muslims sects would state that it is Jesus coming back in a spaceship directly from God. Some other Christians and Muslims sects would say that it is the antichrist instead. 4. UN tries to approve some meaningless bureaucratic resolution about the UFO incident. After some months of talking and debating, it is vetoed by China and Russia just for the fun of vetoing. 5. US will entitle themselves as "the world" and try to establish contact with the aliens. If US concludes that the aliens are friendly, then they came here obviously because they were interested in learning more about the fabulous America's way of life. If they are enemies, it is because they are communists and came to destroy America's liberty. As always, US will forget that there are other countries in the world. 6. Most countries in Europa, Africa and Latin America will just not give a single [insert a bad word here] about it. Oh, we are being visited by aliens, but who cares, let's just continuing watching stupid commercial TV shows and sharing stupid memes on internet. 7. Some visionary prophet will start a new religion to worship the newcomers (which he will state that came from Nibiru and Hercolubus) as the returning god astronauts from ancient Egypt and will announce that this is the start of the war against the illuminati. Also, he will show a "proof" that the Mayans miscalculated the world final date by 12 years and that it will end in year 2024. Millions of people would faithful join the religion (for a small monthly fee, of course). The visionary prophet will then quickly get some millions of dollars in his account, some mansions, yachts, airplanes, Ferraris and Lamborghinis. He will always be seen using a Rolex watch and his multiple top-model wives will dress clothes made from gold and diamonds in Caribbean beaches. However, he will always make clear that all his money is for charity, for African hungry child and for saving humanity in those end days and that he never took a single dollar from his followers for himself. 8. Scientology church, to not get much behind other UFOs religions, publishes a new OT level about Xenu's past plans on planet Teegeeack and link it to the UFOs. But this information would be held secretly and would be released only for those people who had cleansed themselves enough (by providing them a lot of cash), except that it will leak in the internet in the first 5 minutes. Anyway, they would still aggressively insist in trying to sue and persecute anyone that publishes their BS and state that unprepared people who reads it will die from pneumonia. 9. Then, the aliens impatient and deceived by Earth's people disorganization and stupidly, secretly perform some changes in Earth's society in order to match the OP's expectations. Otherwise, the attack would be too easy for them and they would not have any fun from it. 10. After the aliens secretly changes Earth's society in some way, all the governments in the world suddenly agrees to coordinate people about investigating the aliens. They are proud that they quickly agreed that undoubtedly the aliens seems to be scouting Earth and that they will attack. However, in truth, the aliens deliberately gave the information to the humans that they are scouting and that they will attack, and did their operations in blatantly open and obvious ways, including by uploading their full and detailed plans in Youtube already properly translated in a lot of human languages. Otherwise, the stupid humans would probably never figure it out what they were doing. 11. An organized world government finally forms, and perceiving that their time is short, start to heavily and hastily prepare for the war. See part 8 below for more details on some things that they might do. # 4. Could humans war against the aliens? Probably no! Let's suppose that we choose to attack their ships: * They have enough technology to coordinate a lot of spaceships travelling through the galaxy, and who knows how many spaceships are there? * If they are sending a lot of scouting ships that travelled though the galaxy, what would be their battleships? * They surely have a tech level much more beyond of what we had ever dreamt about, in order to be able to achieve spacetravel. * If we could ever harm one of their scouts, an alien counter-attack would probably simply obliterate the humanity, perhaps in a few minutes. Again, they have enough tech for star-travel. * Even if they choose to use H bombs just as the same as humans developed during the cold war and in the same number that humans developed, and then land to drop those and explode 'em, humanity as we know it would be gone and we would not have any way to defend against that. We already have enough technology to wipe out ourselves even nowadays (as 2015), so why would a space-travelling alien civilization not be able to easily do it? Also, they probably would have something much more advanced than that if they want to attack us. So, the conclusion is that attacking them would be like trying to use sticks and stones to defeat an horde of flying Apache helicopters equipped with missiles. No people with at least half a brain seriously thinking about it for 10 minutes would ever conclude that we have even a tiny chance in succeed on driving them away by war. Earthlings would likely try to insist in communicating. But, goddammit, no matter what, we got no answer, at least no answer that we actually could understand as such. They simply don't seems to want to talk to us. Perhaps they don't want to talk to humanity by the same reason that you don't want to talk with the ants that are nesting in your garage. We are just too primitive. # 5. Why could the aliens be here? Ok, if the aliens would like to just destroy this worthless peace of rock and its stupid Moon, or even simply wipe out humanity from the third planet orbiting the Sun, we probably have no chance against them. So, if this is their ultimate purpose, we are probably doomed. 1. Maybe they want a new planet to live and are checking if Earth is suitable? If this is the case, we should welcome them and hope that they don't think about exterminating us. But it would help a lot if they actually wanted to communicate (or perhaps, they are already communicating, by uploading their full detailed plans in Youtube). 2. Maybe they want some mineral, or biomass, or water, or something else from Earth. If so, we could live our lives providing what they want. If they are hostile, but don't want to just kill us, we may be fine by accepting slavery. Of course, this would only be viable if they actually communicate. 3. Maybe they just will take out of this planet or put it here, or do whatever they want to do undisturbed, without telling anything to us. We could watch them in hope of learning something. Trying to attack or disturb them would probably be useless. They would either don't care and just continue whatever is they work, or they would retaliate. # 6. We really need to war against them. How could we have some chance? If we want to war with them anyway, we could have some chance against them if: 1. They are severely depleted of resources. And this could be one of the reasons of why they are coming. If the resource is something simple, they can easily go to Mars or the Moon and get it, but if they are solely on Earth, this means that they need something that is abundant only on Earth. Possibly something developed by life activity or by humans theirselves. What we could do to try to resist is try to intercept them as soon as possibly, use anything that we could do to harm them (like missiles), and try to hide or destroy whatever they want to take. We must put our hopes that their resource-depletion makes them somewhat unable to react or defend themselves properly. 2. They are severely depleted of personnel. Maybe the aliens are just a small couple of pirates or refugees fleeing from their planet coming to Earth in order to hide from their enemies. In this case, if we agree that they are unwelcome, for example, if they are a small number of space locusts that devours all the resources of habitable planets and then just leave for another planet leaving an inhospitable wasteland behind, we should try to locate their members and kill them. Every kill in this scenario is a win even if we lose 10000 humans for each alien kill. If they are not severely depleted on either resources or personnel, and we could not just adapt to live with them at Earth, then we are doomed. Our only hopes is that they are severely depleted on either those, and even if that is the case, we still have few chances against them. # 7. I spotted an alien and want to kill him. What to do? If the alien is inside a flying spaceship, launching a missile might be doable. They could counter attack, but if they are resource depleted, they might instead choose to flee. They might be able to dodge a missile easily, so lasers might be a better option. Each destroyed spaceship is a score for the humans. If they are just walking with some spacesuit over the land, we could attack them with lasers, guns, arrows, stones, whatever. If their spacesuit is sufficiently damaged, this could mean their death. However, they are likely to be armoured, so damaging their spacesuit might be very hard, specially if it is done from some virtually alien indestructible material. An alien walking around could be trapped. We could try to imprison them inside cages or crush them with rocks (probably by strategically positioning dynamites and ambushing them). If the alien is a robot, EMP pulses might also work in addition to explosives, lasers and traps. If they are not armoured for that and unable to dodge or flee, of course. Also, if they are resource depleted, it is possibly that their robots are fragile and lightly armoured. Grabbing parts of destroyed spaceships, destroyed robots and dead aliens is very important. It becomes much better if you can capture and safely hold working spaceships and robots or living aliens. The most that we can collect from them in order to learn what they are and how they behave, the better. Kudos, if you can hack their spaceships and robots to make them work for you, or convince some alien to change side and work for the humans instead. # 8. What to do to defend/resist them? If they decide to just blow up this planet, of course, there is nothing to do. But if they are hostile, but don't want to chase down the humans (or not spend much time and energy in that), other than attacking them with the tactics in the part 7 above (if any of them works), we could: * Avoid them. If they just want to do whatever they want to do undisturbed, we could just let them do. Except if those activities are too harmful and untolerable for us, of course. * Live inside bunkers, mountains, forests, ships on the oceans and any place far away from the aliens. * Learn how to plant yourself, store food and seeds in safe hidden places. If possible, plant in vases that could be quickly moved from one side to the other. Prefer to produce foods that are nutritive, cheap and easy to grow. * Anticipate the enemy moves, and take everything valuable that they might want to use or that would be destroyed. This includes, for example, crops, water and machinery. * Mass-produce solar cells in a size usable by individual bunkers and that are sufficiently cheap, easy to produce and easy to install. We should do that when we still can. * Try to sabotage or steal whatever they produce here. * Invest heavily in seawater desalinization in order to provide people who lives in the sea or near the sea a reliable way to get drinkable water. We must invest on that as quickly as possible before our industry collapses or degrade to a level where we are unable to do that anymore. * For people living inland, provide ways to get drinkable water from rainwater or from rivers. * Invest heavily on communications. If they don't attack our satellites, we should launch as many as possible to ensure efficient communications. Otherwise, we should build the most that we can of ground, underground and underwater communications cables. Coordinating radio transmissions and band-width is also critical. Mass-producing all the equipment for that is also very important. And very important, deploy that f\\\ing IPv6 for once and all, we already had enough of IPv4. Invest heavily in recycling materials. Avoiding wasting anything that could be useful. * Invest heavily in projecting machines that are cheap, easily producible and are easy to fix or replace parts if broken or damaged. * Invest heavily in war education. Everyone, including child and elderly people, need to be trained on how to act quickly and correctly in order to don't help the enemy, nor be a victim of them and to attack or sabotage them. The training also helps to improve resistance coordination. Collect as much information as possible from the aliens and teach whatever not deemed too secret you can. A lot of people need to know how to attack the aliens and also teach that to the others. Further, the education should be bended in a way to not tolerate traitors and to make people suspect on any behaviours that a potential traitor could have. In other words, what humanity need to do to defend itself is similar to what a nation being invaded by an enemy army and trying to resist that does in a war. The economy and people behaviour change directly in accord to that. Think in what was Soviet Russia, UK and Nazi Germany during WWII. The economy of those three countries turned almost entirely into a war economy, trying to frenetically outperform the enemy as quickly as possible and harm it at the same time. Parts of the economy deemed as superfluous suffered or even stopped during wartime. [Answer] Massive spoilers for Liu Cixin's The Dark Forest, which has an unusual answer to this. > > Threaten to appeal to the galactic community. > The idea being that if there's one alien race that can find Earth, there's probably a lot more in the galactic neighbourhood. And however advanced this alien force is, there will always be a bigger fish out there, and these aliens will not want to draw the big fish's attention. > Whether these other aliens are benevolent or malevolent would be hard to predict, but there's at least a decent chance they will be utterly terrifying to the invaders. > So, prioritise communications technology. Try and get communicators off planet. Launch probes into deep space. Put everything you have into high powered transmitters. Make absolutely clear, that if the aliens do not desist, you will broadcast Earth's presence and what has happened here far and wide. > > > This will work for aliens even substantially more advanced than humanity, which is what most of the other answers are missing. [Answer] Depending on how certain the UN would be, that the aliens will definitely attack, there are multiple options. In the past NASA and the U.S. military have discussed plans on how to defend against incoming asteroids. In fact the U.S. military has nuclear weapons just in case that would happen. As this seems to be an actual strategy this concludes that a nuclear warhead could be shot into the earths orbit or beyond. I assume that your aliens, even if they are advanced in technology, can't protect themselves on subatomic level, this could be a way to attack them. It however may not make sense if their spaceship is armed and could in some way destroy the rocket/missile. If we would be able to see the spaceship this could perhaps be spotted beforehand. What we should consider is, that shooting down the small ships would not help at all. It would rather shorten the time for a counter-attack and we might run out of warheads in case bigger ships would appear later on. A possibility would be to let them land. It would be perhaps be enough unknown territory for them, that we would have an advantage. This could be for several reasons: 1. They need to wear protective gear. No matter what shape or size they have, earth's atmosphere is dangerous for them. This might be because they cannot breath our air, their chemical components are based on Sulfur or most certainly they are not immune to bacteria, virus and fungus. This would slow them down. 2. They come to earth for a reason. Assuming the aliens are not just slaying for fun, they want something from earth and they need it so much that the mobilize an entire fleet of spaceships. If we figure out what it is, we may discover a big weakness. 3. During landing they likely need to slow down. This makes them an easier target. A big problem would be if they attack from space, then we would be back to the very first option. Even if it might not be the most realistic scenario, it could be very effective to use biological warfare against aliens. Assuming they do not wear protective gear inside their spaceships, humanity could try to get astronauts up to one of their spaceships. Maybe they could access their ships, either by force (which would likely not work, because then the aliens inside the ships would die, when the ships hull is broken) or by arranging a meeting is some way. Then they could release the agent inside the ship infecting the aliens. If humanity gets lucky, the aliens are returning to their base like they did before and infect the other aliens. Sounds pretty cruel, but it might work against killer-aliens. Perhaps you could also do the peaceful attempt and not attack at all. They might get into contact with us humans and they do not want to fight. As far as we know they travel across galaxies just to visit us, so just based on some air maneuvers it might be a little shortsighted to assume the would bring instant doom. The mayor problem with this scenario is, that it pretty much defies our knowledge about physics, as the aliens would need to travel faster than the speed of light to be returning shortly after leaving for there home planet or base. So if we take this into consideration and assume that they use hard science to achieve that, we are likely not going to stand a chance against them. If they came to destroy humanity their weaponry would be as advanced as their space-travelling and I doubt we could compete. [Answer] I'm going to go out on a limb and say do nothing. I'm not joking. War, and preparations for war are expensive, and we know nothing about them and their goals. How can we tell the difference between a cat surveying for prey and a deer looking for plants to eat? The one thing we do know is that their technology is so unbelievably absurdly vastly beyond ours that there is no reason to believe we could even hurt them if we tried (moving so fast they might be teleporting? Do you have any idea how much one of our fighters would kill for that kind of maneuverability to avoid our best of the best interceptor missiles? What would we even throw at them?). We don't even know if we're looking at all the civilization has left in a spacepod, or if they are one of a trillion trillion world empire with powers beyond our imagination. Are they the brilliant creators of their spacecraft, or did they just jimmy the lock when noone was looking and joy ride for a bit? Frankly, we're so outclassed in every way that our best approach is to use Arthur C. Clarke's rule: Any sufficiently advanced technology is indistinguishable from magic. Rather than wasting our resources at a futile attempt to attack something unimaginably beyond our comprehension, spend those resources on making our life better. The resources spent toward the aliens should be spent similar to how a village might spend its resources towards a wizard who has not actively doing anything to interact with us. Perhaps try to communicate with it. It's certainly no more risky trying to communicate than it would be to try to attack, and it is probably more likely to succeed at gathering intel. Once we increase our knowledge of what is going on by an order of magnitude, or by an order of magnitude number of orders of magnitudes (or perhaps even an order of magnitude number of orders of magnitude in the number of orders of magnitude), then we could begin to whisper the possibility of preparing for a war. At the point you have, our intel is so unbelievably utterly useless that not even Kim Jong Un would smack the shiny red button to order an attack! The Illustrious Leader is way smarter than that! [Answer] First, let me say that a small starship which does not communicate might well be a relatively simple scientific probe. If [New Horizons](https://en.wikipedia.org/wiki/New_Horizons) did an Earth fly-by or went into orbit, it wouldn't answer our calls, either. It was made to collect data, not to communicate. As the first probe detected signs of life, they send another one with more specialized instruments. But people on Earth would be preparing for the worst anyway, so the intentions are irrelevant. The aliens did not develop in our solar system. So they are capable of interstellar travel. * Do they have some kind of FTL drive? That's technology beyond our understanding, like a mounted knight who gets hit by a Predator drone. On the plus side, we don't know how good the rest of their technology is. Perhaps the FTL drive is just a few years beyond our technology, and the rest isn't much better, either. * If they don't have FTL, it is even worse. They were able to accelerate a ship to a significant percentage of lightspeed. If the next ship decides to fire a missile before it decelerates, they can fry Earth. My prediction for what happens: * Mankind forms some kind of global government in case the aliens want to talk. This government won't be very democratic or very strong. The US and China make a deal, EU, Japan, Russia and India are strong enough to be on the table. A few "rogue nations" are quickly and messily eliminated (North Korea, Syria) to get the "home front" into order. Using that precedent, some countries label their enemies "rogue" and take them out, too (Venezuela, Iran). * Any nation which can build kinetic or nuclear-armed interceptor missiles will do so. That's a pretty long list. The global government might try to ban nuclear tests and missile tests to we don't look like a "rogue planet" to the aliens. * NATO, China, and Russia will form some sort of Global Aerospace Defense center comparable to NORAD. * Ground forces are mobilized and dispersed from their peacetime bases. That's as much for internal security as for defense. [Answer] # Passive Defense * Bunkers for public * Building up doomsday food stocks and cache of seeds etc # Militaristic Defense * All airforces on high alert * International coordination for assault management. All countries agree on sharing information and sending troops to wherever the aliens assault. * Very high altitude aircrafts patrolling the skies. Several space stations focussed on tracking the activities of the alien spaceships. * Efforts to track mode of communication between the unknown spaceships. Efforts to scan the interior of the spaceships with ultra-high power x-rays. Coordinated efforts to find out what is the level of technology of the invaders. [Answer] "Humans chose to stop fighting themselves and cooperate in order to defend Earth" I am not sure how to take this information but I am going to assume that there is formed worldwide alliance with one "major government" (even tho its not possible so soon, even if there would be alien assault on the earth) "Year 2020." Assumed by given informations I think that the technology is not developed enough to build space ship for battle or even escape. Now few questions and answers based on given informations, so from the given info I assume that there is going to be attack for 100% and mankind knows it. First of all lets think about survival of our kind before we think about fighting them. Some resources have to be moved in to this matter, the best solution would be to create infrastructure under the earth, if the aliens don't intend to destroy whole planet this is our best chance of survival. Best place to start building this if we speak about weather and climate would be England and Australia so from the scratch we should move workers and other needed supplies in to these two "places" and start constructing underground "shelter" with top reinforced with best possible metal. Now Assuming that this construction has started and we can start with moving and building some facilities in there, we can safely expand and move more in there until the "attack". This move should give the humanity biggest chance to survive even if we should lose the fight. Now there are several options of our next priority. Most of the armies around the world even today have special forces and technology in their armies which are "unique", now when the world is under the flag of an alliance we can unite all the forces at our disposal. By creating "military council" from the best of the best in the world we can really move our training and the art of war forward by the speed of light. By combining best techniques considering all + and - of every existing special force with this capacity we should be able to build "ultimate" training program and start with building new army. Biggest drive for first generations of new soldiers are going to be driven by "fear" from the alien assault however this effect is going to fade away the longer the aliens take before the attack. First few generations of new "super-soldiers" should be still ready in short amount of time. Now speaking about the "tools of war" we have biggest experts from the world available so creating and developing new advanced arsenal adapted to our needs shouldn't be a problem. First matter If they don't want to destroy whole planet they have to invade the planet with their own troops. Its a wild guess but in the end if we don't have any other chance, since we are moving civil population in to our two shelters we should shatter base of operation in big abandoned cities probably in USA. They are best choice for partisan tactics a.k.a. hit, run and hide. Now when basics are clear and so is tactics chosen for battle our attention should be moved on developing of AGM/ASM warheads. IN the time we have left (if there is any) we should keep pushing development of everything above + move some resources and try to develop missiles against their spaceships. [Answer] Well any race jumping across the Galaxy would have the tech to destroy our planet, at least kill (almost) all life on it. We can't stop that, not now, probably not ever. Because sending a decent sized projectile at some %c will be almost impossible to detect in time to even think about a defense. So we will have to assume that if they war with us it is because they want at the very least a habitable planet and worst, Us. So at this point we would start trying to make defenses that, one we are capable of making and two actually might work against probable attack vectors. Such as, will they be landing troops? If so Rail guns that can launch relativistic projectiles with some accuracy would be high on everyone's development list. if time and money allowed installing some on the moon would be an excellent ring of defense. Since a ship can only enter the atmosphere at relatively slow speeds they would be sitting ducks if we had a weapon that could throw stuff fast enough, but we would have to catch them off guard, since any ship that can travel between stars will have powerful enough shields to stop or deflect things coming at them. Needing similar smaller weapons also to fight against any ground troops that land. Otherwise, not knowing what they want, what they need or anything about their biology to prepare poisons, or psychology for psych warfare we are mostly left with designing large powerful guns and hope for the best. (Lasers are not as good as an options for big guns because they require a much larger power source to produce similar impact, to the best of my knowledge.) [Answer] Well, let's send an unarmed, unmanned probe with lots of scientific and spying gadgets, to photograph, ecograph, radiograph, smellograph, x-ray-o-graph, etc-o-graph, them. If they are indeed hostile, they will quite probably destroy the probe. Great, we now know that basic piece of information: they are hostile. If they don't destroy the probe, we make it attach to one of their space ships, in order to make more tests. We will see if they try to remove it, and whether violently or gently. If they don't, then the probe will go back with them when they withdraw (if they withdraw). In such way, we will discover how they move, at what speed, and in what direction. --- They must come from very far away, and use vehicles and drives adequate for this long distance, or we would have detected their radio transmissions long ago. Unless for some reason they do not communicate via radio, but in this case it is difficult to believe that they would have developed space travel. [Answer] We would certainly not be able to defend against an invasion aliens if they are more intelligent than us. However, that isn't the only possibility. It's perfectly reasonable to assume that the invading aliens are not intelligent at all. Suppose that civilizations that undergo rapid technological evolution almost always become machine civilizations. Then, just like most organisms are susceptible to developing cancer, you can imagine that on the long term, machine civilizations are unstable to developing the analogue of cancer; they degenerate into a collection of dumb machines that just hop from solar system to solar system making copies of themselves. Then if Earth is invaded by aliens are only hope is that they are such dumb machines. They can then be fought off by studying what conditions the machines avoid, e.g. they could stay away from water, and then using that to get rid of them. [Answer] You've stopped thinking we're alone right? Then stop thinking there's no one else. The technology might not be too far or they would just: 1. Ascend into the 4th dimension or higher. 2. Leave the galaxy and find one with a better resource. 3. Go and compete in a more valuable place, such as the center of the universe or where it began to make scientific research. 4. Remain in an utopia and/or help others achieve it like them, once we're great enough to contact others. Remember, we're very outdated in contacting. 5. Rule the galaxy? Just get reconquered and/or rebelled. Only freedom stands strong. Now if we stay xenophile other xenophiles are likely to help us. If we stay xenophobe noone would help. Now, if to contact aliens is to ask for help then we can go to war together against threats. Don't discriminate! All sentient beings should be treated equally. ]
[Question] [ In most 4x games, almost every space nation fights for star systems, planets, black holes, etc. The benefits are obvious: planets to colonize or mine from, solar energy, strategic positions and so on. Now lets turn that concept on its head: why would these space nations be interested in completely empty space, far from any planet or star? Why would they value it as much, if not even more than star systems? What could they find there? I can think of a couple strategic reasons myself: * Matter / gravity disrupts Hyperspace lanes and exits, meaning that using them is only possible far away from any star systems. * Jumpgates allow for instantaneous travel between them, but also become a massive weak point in a war. If one blows up, the explosion could destroy a whole system - so placing them far outside of star systems would be safest. * Sensitive sensor arrays meant to secure borders work much better without too much space dust or asteroids flying around. * Some science research that requires less gravitational interference. * No intergalactic rules apply here, allowing for the deployment of minefields. * Some sort of vacuum-based energy generation? (I just assume that empty space far away from celestial bodies has less gravitational interference - but I may be wrong!) While the above reasons may push a space nation to want some empty space, it wouldn't really motivate anyone to go far beyond their own borders. Especially considering that there's more vacuum than stuff out there, so there's more than enough for everyone. Another issue is, that I want them to be more interested in empty space between star systems - not "above" or "below" them. Almost as if space would be treated as semi-2d plane - but I can't come up with a good reason why that void would be better than any other void. What other things could possibly motivate nations to engage in wars for essentially empty space between systems? [Answer] The Electric Universe people were right. There are plasma filaments connecting all the stars, carrying incredible amounts of electric current. Only between the stars is it possible to tap into that energy, so the areas in the middle of the filaments are hotly contended. [Answer] Energy generation In the vastness of space there is something. We don't know what it is or how to see it, but we can see it's effects. It pushes whole galaxies apart, while seemingly invisible. This is dark energy. There is a great abundance of it to be so powerful and most is likely in the vast emptiness of space between star systems and galaxies. Stars, planets and black holes all can make a ton of energy for a space nation. Yet when they found out how much energy you can make with dark energy, it made the rest practically obsolete. The power can also help travel. For the same reason dark energy is pushing everything father apart, so it can be used for high speed travel, potentially FTL. All you need is the dark energy residing in the vast emptiness of space. Go there and start harvesting! [Answer] Vast voids which are devoid of gravity, particulate and radioactive interference are the perfect place to grow the flawless crystalline structures needed for the post-singularity level artificial intelligences. The computing power of any AI is strongly correlated to the size and purity of the circuitry that it lives in. Every supreme intelligence at the heart of every star empire is constantly expanding its hardware, integrating newly grown chips into its hosting platform so that it can grow ever smarter. To fail to grow faster than your adversaries is to fall behind in the only race that matters, the race to Godhood, to supreme mastery of all that is. Any empire which fails to control the majority of the best crystal growing voids is destined to die at the cybernetic hands of the empire which holds those voids. [Answer] By far the best natural resource is to be found in empty space is emptiness. * The French tested nukes in the Algerian desert. Americans decided to nuke their own desert. Apparently deserts are fun to nukes. Well empty space is the desert of the universe. You can test all sorts of weapons, maneuvers, and other schemes far from prying eyes, and far from something you don't want to accidentally damage. You can also isolate the influence of celestial bodies out of the equation, which is useful for testing and for science. * You can discard a bunch of junk that you never want to see again. You could do that in orbit of your planet or star, true, but if you have a lot of space-activity you run the risk, however small, to collision with space debris. If you discard them in the middle of nowhere, the risk becomes zero because nobody (that matters at least) goes there. And since it's so far away from the public eye, it's like it never happened. There is of course no equivalent in the real world for rich people/nations discarding their junk into empty spaces. None. * You can discard a bunch of people that you never want to see again. Space-Alcatraz! Again, you could have a space-prison around your planet or star, but that's within reach for a daring breakout. Successfully escaping becomes much more difficult when you're in the intergalactic void. Which means any attempt will have to be even more daring! And if there's anything you don't want, it's your prison break stories to be average. [Answer] Matter generation What we think of as empty space is full with activity. Thanks to fluctuations of the quantum field virtual photons pop in and out of existence, one positive and one negative, which cancel each other out. With light these can be turned into real photons, which means you can create something out of basically nothing. Uf you push this real quantum physics to the max, you can influence the field to your benefit. You can push the virtual particle pair to start far apart from each other, as well as making them much bigger. Then you turn the virtual particles into real particles and voilà! You've created actual matter. With full control you can create any molecule you want. Possibly even any material if you control a lot of molecules at the same time in a certain position. Matter also means energy. That is what the E= mc² is all about. It means that in any mass there is an absurd amount of energy. Creating matter thus is the same as creating energy. You need the vastness of empty space to truly control it. As little interference as possible, as the fluctuations of the quantum field are hard to control. Any unexpected particle of dust can throw the machines off, so you need the most near perfectly empty space away from anything else you can muster. [Answer] Hiding valuable assets In a sufficiently populated galaxy, there could be countless potential threats and attackers in all directions, too many to keep track of or anticipate. Space is just too big. So instead of expensive force fields and hyper-sensitive early warning systems, every civilization will locate important installations in large regions of empty space and simply have it go radio silent. It would be futile for a hostile alien race to search such a vast region of space and so, your species' embryo bank, or ultra-rare exotic mineral or whatever remains safe. Safer than with traditional shielding or military protection, without any of the cost or energy needs. This would be a sensible way to protect any asset that may be a target of attack, and all you need is to securely record the coordinates if you need to reach it later. [Answer] Computation is more efficiant at lower temperatures <https://en.wikipedia.org/wiki/Landauer%27s_principle> So lets just say you are running tons of simulations you might want to get as far away from a heat source you can [Answer] ## Shipping lanes You can tax people for going through your "trade route", which has been done for centuries here on Earth. Set up space buoys to warn people they will have to pay a toll, or not, then enforce the toll. Not many governments would care about empty space, so they aren't going to war over the toll. They'll just go around it. Well, that is until the volume of the tolled space becomes too large, then they either give up and pay the tolls, or go to war, and not many politicians would go to war telling their constituents that it's because of empty space they don't want to pay a toll for. ## Bragging rights Since there's nothing in these spaces, you can take them over pretty easily. Then you tell your ~~peasants~~ citizens about how much you've conquered during your ~~reign~~ time in office. > > We've expanded our empire 3x since I was "elected" just 20 years ago. > > > Of course, the expansion has holes in it where actual solar systems exist and are run by other governments. ## Space junk There's a ton of resources "just laying around out there". You can mine nebulae, asteroid belts, or whatever else is floating around without any obvious "land rights" to them. Of course, unless you have super cheap fuel/reaction mass, massive cargo ships, and extremely fast shipping, mining from even outside your own solar system is going to be slow and expensive to the point where anything you recover is going to cost you more to get than it's worth and be months/years in travel time. And mining within your solar system will be far easier, cheaper, and faster, so it's just another political ploy to distract the masses. [Answer] I think the biggest advantage of empty space, is that it is empty space. Obviously, it is not actually empty, as most space has some amount of stuff in it like very dissipated hydrogen gas. That being said though, empty space is important, as especially deep space, in-between stars, is lacking in interference. Interference takes all sorts of forms that you would want to avoid. Perhaps it is gravity from nearby bodies. Maybe you have very radioactive spacecraft that you want to keep away from earth or other inhabited worlds. In the context of an interstellar civilization, empty space is a place where other people will not be bothering you. Considering that crossing interstellar distances, you don't really have the opportunity to stop if you pass something interesting, putting a base of government or criminal origin out in the middle of nowhere would be beneficial. You see something like a space pirate lair "hidden" in the midst of some asteroids, but considering that asteroids are valuable for mining and colonies, if you want to be left alone, they probably aren't the best place. Taking an asteroid out into empty space perhaps, but unless your interstellar civilization has just left a bunch of asteroids somewhere alone, because they haven't reach out that far, or are just swamped with resources, you'll want such hidden bases out in deep space. Considering the breadth of sci fi topics his channel covers, I'd recommend looking at the Youtube channel Isaac Arthur, as I'm sure he's done some crazy video on harvesting energy from quantum fields in deep space. [Answer] ## They're outlaws A race of people who make a living via piracy, raiding, smuggling, or other illicit activity might choose to hide out in the emptiness of space. The void is so large, it's just wildly impractical for the Space Police to even try to search for them in such a large empty region. It may not even be possible to reach those regions if your FTL depends on being near gravity wells, so only the smugglers hiding out there know the tricks to reaching these regions. (A few loops around some high-mass stars or black holes to build up velocity, followed by a push into a very specific trajectory to reach their refuge - a degree or two off and you'll completely miss it and not even come close enough to know there's anything there. Almost literally "Second star to the right and straight on 'til morning".) [Answer] ## Stars are scary Stars spit out all kinds of radiation, they have flares and mass ejections and magnetic disturbances, sometimes they go nova, and in any case they have all of this stuff whirling around them all the time that might end up on an impact trajectory with an inhabited planet. Some people might find living on a rogue planet in interstellar space boring (and you have to wear a really warm jacket), but it's safe and predictable. But without any convenient planets or asteroids nearby, and without cheap solar power, they're more reliant on trade than most, so they look for places along the routes between solar systems so they can trade for certain essentials. ]
[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/96615/edit). Closed 6 years ago. [Improve this question](/posts/96615/edit) Partial extension to this question: [What kind of natural armor would stop bullets?](https://worldbuilding.stackexchange.com/questions/96503/what-kind-of-natural-armor-would-stop-bullets) I was wondering what kind of jaw and tooth build would be able to break armor which can withstand 4 gigapascals to 25 gigapascals. This would have evolved naturally, as many creatures on this planet have very tough armor. The closer it is to the higher end of the pressure, the better. This creature is a carnivore. [Answer] # Ambush Predator to Start Conventionally, this predator will need short jaws, pyramid shaped teeth, and slow twitch muscles. Even if the predator can't crack the mantis shrimp style armor, it doesn't need to penetrate to be effective. Crushing the armor by causing the sides to snap may be more effective than trying to punch through. # Be sneaky, use HESH Making frontal assaults on super strong defenses is exactly what Sun Tzu advises you not to do. Attack sideways. In the days of WW2 tank warfare, the British used a type of ammunition called [HESH](https://en.wikipedia.org/wiki/High-explosive_squash_head) - High Explosive Squash Head. The idea was that a plastic explosive would hit armor plate, flatten out against the plate then explode. The explosion caused a huge pressure wave to travel through the armor plate. When the pressure wave hit the back side of the armor, it would exceed the structural strength of the steel and cause splinters of armor to go whizzing around the inside of the tank. The point of HESH wasn't to punch a hole through the armor as much as use the armor itself to do damage. However, with the introduction of spall liners and spaced armor, HESH became less useful. But this predator's prey won't have spaced armor or spall liners. To use this HESH idea, build a predator with quick-closing thick jaws with teeth shaped like hammers. If the jaws close fast enough, they'll do the same thing that HESH rounds do to tanks. Little bits of high speed armor fragments from the inner side of the armor will go whizzing through organs, muscles, bone, and blood vessels. Even if this doesn't kill the prey, it will seriously impede their ability to retaliate. # More Real Life Analogs Medievel armor and weapons fell into a very similar situation. Plate armor is basically impenetrable by blades of any kind. In response, knights and infantry started equipping war-hammers to bludgeon the enemy knights to death. Armor won't help you much against percussion attacks; you need extra padding and extra space between the armor and the juicy bits inside. [Answer] Let's take this from another angle. Turns out Earth-life has done much of the work for us, giving us a menu of options: Crocodile Model Clearly this armor is tough. Probably too tough to bite straight through it. So pure biting force is not what you need. After all, the armor has to connect to the body, right? That's the weak link your predators need to exploit. I'm thinking about something like a crocodile, which grabs onto a limb or piece of flesh and then spins rapidly until the torque rips the desired piece straight from the body. Whatever connective tissue is holding the armor onto the body will eventually fail. So you need high pressure bite; not enough to defeat the armor, but enough to hold on through the whipsawing action required to rip the armor off the flesh. Starfish Model Starfish face the same problem. To wit, armor on clams, which they can't defeat. So they simply shrug (with five limbs, you gotta see it), extrude their stomachs, and digest whatever they can reach until the shell pops open. Lamprey model Lampreys don't really typically deal with armor per se, but their form factor would be good to challenge an armored creature. Imagine your predator might have a long snout which can dig around to find joints or gaps, then push into the prey to eat it hollow from within. Update -- More Love from the Animal Kingdom Spider Model Many spiders are patient, and don't really enjoy the notion of sucking solid organs through a straw. So they inject their victims with a powerful dissolving agent and wait awhile for the brew to marinate. (This is easier to do with exoskeletal creatures who come with a built-in "container", but workable with other creatures too) Then they can slurp up the nice liquefied insides with little trouble. Anaconda Model "Chew? You expect me to chew my food? Who has time for that?" This is the motto of snakes worldwide. Who needs to puncture the armor when you can swallow your prey kit and kaboodle? Then you can take a six-month nap while you digest it. Note that the constrictor model may be even better, as armor designed to face up to frontal threats may well fail under compression from the sides... Eagle Model I've seen videos of birds of prey picking up turtles and dropping them from great heights, thus cracking their shells. You might be able to work with this. Also, I've seen video of eagles knocking goats off a cliff, showing that this works with larger prey. It's a little cold, but ... birds, y'know. Savage dinosaurs the lot of 'em, they'd slay us all if they could. Update -- Okay, the gloves come off Mantis Shrimp Model Invincible armor, huh? This has been mentioned in another answer, but let's highlight it some more. These shrimp "cock" their punching arms compressing a flange which wants to spring back hard. So when they strike, they get momentum from muscle as well as from the flange springing back into shape. They strike with the speed of a rifle bullet: > > When Sheila Patek, a researcher at USC Berkeley, tried to study these heavy-hitters on video, she hit a snag. “None of our high speed video systems were fast enough to capture the movement accurately” she explained. > > > Turns out the strike is so fast it leaves a vacuum in the water, which creates heat and light when it collapses. If a predator using this principle hits the armor, that may well be enough to defeat it. Even if not, the transmitted shock will be enough to ruin the armored creature's day. Here is a meditative picture to help: [![enter image description here](https://i.stack.imgur.com/WSxQC.jpg)](https://i.stack.imgur.com/WSxQC.jpg) Limpet Model Thanks to mlibby in comments, we have become aware of the mighty Limpet, whose teeth are so strong that the limpets accidentally swallow rock fragments they tear free while scraping rocks for food. From BBC.com: > > The teeth are made of a mineral-protein composite, which the researchers tested in tiny fragments in the laboratory. > > > They found it was stronger than spider silk, as well as all but the very strongest of man-made materials. [...] fibres, consisting of an iron-based mineral called goethite, are laced through a protein base in much the same way as carbon fibres can be used to strengthen plastic > > > Your predators can have teeth made of this same material and just rasp through the armor. I'll leave you with a close-up of limpet teeth, to ensure screaming nightmares for months... [![enter image description here](https://i.stack.imgur.com/wzcyM.png)](https://i.stack.imgur.com/wzcyM.png) [Answer] Just a big, strong jaw. It's only a matter of being stronger than the armor. Teeth matter a little. Sharp teeth let you get more pressure from the same force. The teeth need to be strong enough to not break. If the goal is to pierce the armor, then you want long, strong, sharp teeth. Like a saber tooth tiger. If the armor is easier to crush than pierce, then you want stout teeth with many sharp points of contact. Like a crocodile. Or a moose. But the strength of the jaw matters more than the teeth. At a certain point it's just about biting harder. To exert a large force, you need to be able to actually get your mouth around the target. That means your mouth needs to open wide enough to get on both sides of your target. And big muscles to close the jaw. Strength in biology is quite often about bigger muscles and thicker bones rather than better design. [Answer] This creature is in serious trouble. The strongest bite known to man is the crocodile's, at 0.02 GPa (<https://news.nationalgeographic.com/news/2012/03/120315-crocodiles-bite-force-erickson-science-plos-one-strongest/>). You are talking about two or three orders of magnitude more, which is a lot. But not all is lost for your chomper. Consider the following possibilities: 1. Eat first, dissolve later. Just like a boa (<https://en.wikipedia.org/wiki/Boa_constrictor>), your predator doesn't even bother to break the armor. It swallows its prey whole, and digests it in its gut. 2. Corrosive saliva. The predator's saliva reacts with the prey's armor in a manner that greatly diminishes the armor's resistance, thus making it vulnerable to a reasonable bite. It could even go for the eyes or some other sensitive part first, to cause incapacitating pain with its corrosive saliva, before going to work with the armor. 3. Persistence hunting. It worked for your great-great....great-grandfather (<https://en.wikipedia.org/wiki/Persistence_hunting>). The thick armor is unimportant if its owner dies of exhaustion. [Answer] Saw the armor instead of biting through it If the material is extremely impact-resistant, we need to change the tool. I am not sure what would be scratch resistance of this armor, but I bet it can not be very high. This way, attacker can bite like a shark does, by sawing off the limbs instead of simply biting them off (like most predators do). The attacker can have a large number of small triangular teeth which together act as a saw. Those teeth need to be only somewhat more scratch-resistant than the armor, and there is not much of a requirement for impact resistance. Another approach is to go after the chinks in the armor Predator can have long sharp claws (or beaks, or teeth) that penetrate between the armor plates and wring them apart. Some [predators](https://en.wikipedia.org/wiki/Snail_kite) are adept at attacking shelled prey in that way. [Answer] Abrasive tooth on either a high-speed reciprocating jaw or on a rotary jaw. (The G'Kek [species in David Brin's Uplift universe](https://en.wikipedia.org/wiki/List_of_Uplift_Universe_species) have rotary limbs.) Grind the armor away at a relatively fine scale, using tooth material which may be consumable or may be exceedingly hard (e.g. diamond or tungsten carbide), at least at the edges/faces of the grinder. Jackhammer / woodpecker jaw is a variation of this. Hydraulic jaw; tooth can be grown or found (e.g. stones), jaw wraps entirely around prey, and teeth are pressed into the armor. Water-hammer jaw; prey's armor is immersed in incompressible fluid and the predator causes the incompressible fluid to slam into the armor. Might find the weak spots in the armor which occur naturally due to the shape in which it's grown but which is not easily detected. Liquid cavitation jaw; prey's armor is immersed in fluid which the predator causes to cavitate then flow against the armor where the bubbles collapse. Abrasive liquid jet; predator pierces (or if the armor has an edge, slices) the armor by spraying it with high-pressure liquid full of microscopic bits of glass, i.e. plankton skeletons. May not be appropriate for biological creatures, but here's 2.5" thick steel being sliced slowly by water with abrasive: <https://www.youtube.com/watch?v=LB0oT5AEJfA> Two opposed giant "piercer" teeth with a massive, strong jaw, like an upscaled snapping turtle. [![Snapping turtle face](https://i.stack.imgur.com/06Lkf.jpg)](https://i.stack.imgur.com/06Lkf.jpg) Each tooth is a pyramid shape and the point is hardness-enhanced with some secretion which is more hard than tough. Armor which is as strong as the tooth becomes prohibitively expensive for covering an entire animal, in terms of minerals or the ability to move. Heat or cool the armor chemically right where the jaw/teeth are trying to bite into it. The jaw is as much an applicator for exotic chemicals (or high-power electric discharge) as it is for biting. Glass-cutter and wedge/split the armor; basically using a small and hard tooth to make a shallow crack in the armor (which it is designed to tolerate - that's why it's so tough) then encouraging the crack to propagate in a destructive way, either by lifting the cracked edges of the top layer and applying the tooth to the next layer (possibly by a shaped tooth which can lever off of the layer(s) of armor it has already cut and bent away), or by grabbing the armor in multiple places and flexing it. [Answer] The probably best approach would be not to break the armour at all but to kill the prey. Doing so does not require breaking the armour since while the armour may withstand ridiculous pressure, the animal on the inside won't. Once dead so the predator can be sure the prey won't bite him in the intestines, the predator can swallow it whole. Might take a week or two to digest, but who cares. Whatever armour an animal has, it needs to be either partial or flexible in some way or the prey is unable to move at all, or, well... breathe. That means that no matter what, you can compress it, without the need to break it. You don't even need excessive force if you rely on e.g. the prey breathing. Just do as some large snakes do: Hold tight, and every time the prey takes a breath, follow the motion and hold a little tighter. Only just, never release until there's no more movement for some minutes. ]
[Question] [ Recently, I asked [How would government change if everyone died by the age of 25?](https://worldbuilding.stackexchange.com/questions/29199/how-would-government-change-if-everyone-died-by-the-age-of-25) as something of a thought experiment. After some consideration, though I've developed the premise a bit further, and I'm working on more aspects of the world. Some of the basic points (including things that I've changed): * The land of Xenqu is, to the knowledge of its inhabitants, the only inhabited place on the world, though they haven't explored much of it yet. * They're at a medieval level of technology. * They've developed a hereditary disease, which began in the year [X]. At that point, anybody who was 25 or older died instantly. From then on, anybody who was descended from some Xenquan dies on their 25th birthday. Is this possible? Can some sort of biological weapon (so it doesn't have to be an actual disease) exist that is applied once (in the year [X]) and thereafter kills all 25-year-old Xenquans? I'll fall back on magic if I really have to - I'm envisioning a case where a dying evil master magician casts a curse on the land - but that's only as a last resort. [Answer] Your entire world is an immersive virtual reality game, played by future humans whose technology has cured death. They are immortal and bored, so most of the time, they play video games about the good-old day when life was short. ...and 25 years is the amount of time you get for a quarter. [Answer] The problem with something like a disease, or radiation, etc is that the "disease" has no way of knowing when you turn 25. It's also highly suspicious that it doesn't seem to affect you at all growing up, but then suddenly you die on your exact birthday. It's ridiculous. More realistically, this disease would kill you *around* your 25th birthday - with some very strong individuals living to be quite old (27 say), and some weaklings dying at 20. Then it becomes more realistic. 1) Nanobots that infiltrated the population from the wreck of a crashed alien drone (in their medieval views their people scavenged sky metal and suffered a curse). These nanobots infected the hosts, etc. 2) A curse on their ancestors cast by a God/powerful wizard. (oops, you covered that) 3) That's just their genetic make-up. When you really get down to it, you don't really have to explain it. None of the characters would know what "genetics" are anyway, so how could they "talk" about it and explain it to the reader? 4) The radiation of their star slowly saturates your body and kills you around the age of 25 - because that's just how the timing works out (this premise if kinda shaky for some very obvious reasons, but hey, it's your imaginary universe) 5) On their world all people are infected with a parasite that is ubiquitous - simply can't be avoided - everyone is infected in the womb, or shortly thereafter. When that parasite "matures", or it itself dies, it's death/departure kills the host. This parasite/human relationship is symbiotic, and the human receives some benefit from it. When the parasite leaves the host, its death is somehow beneficial to the world as a whole, and thus people see their short lives as being lived in sacrifice to their world. Freaky as hell, and a pretty good explanation as such things go. I can adjust some scenarios and flesh them out on request. --- I'm going to roll with the parasite, and make this stuff right up: Scenarios: a) The world was a perfectly normal place, as this universe goes. Then one day, an alien craft/asteroid crashes on the planet. This craft contains a parasitic life-form which attaches itself to its host, and spreads aggressively: perhaps it releases spores into the water/air which infect the host and cause that malignant life-form to grow inside its victim. There is simply no way to remove it without killing the host. Being of alien origin, this life-form has a life-span of its own: exactly 25 years. The victim dies not on their own 25th birthday, but on the 25th "birthday" of their parasite, which may have infected them a few days after birth, for example. b) The world was a perfectly normal place, until one day an alien craft/asteroid crashes on the planet. This craft contains an alien life-form which is highly intelligent, but parasitic in nature, and which cannot survive for long on this world because of certain factors (radiation from the Sun, etc.). This life-form uses psychic powers to communicate with the human elders. They propose a trade, to be accepted by the elders on behalf of all their descendants, or until a "rescue craft" arrives to take the aliens away (which might take many centuries to get here, but the aliens are crafty, and don't say this outright): To allow their species to symbiotically attach to human hosts, in return for great power to those who "link" with them. However, there was a catch in the deal that the elders, foolishly thinking they could trick the aliens, accepted. When the host reaches the age of 25 - physical maturity, and thus greatest vitality - the alien claims its prize for having enhanced the human for all that time: it completely drains them of vitality, killing them, but extending the life of the alien, which is then passed to another host. There can be great benefit to the alien attaching itself to a human: they might reach maturity faster, develop greater strength and intellect, as well as being immune to diseases, healing injuries faster, etc. Any who try to detach the alien, are killed by the alien host. Any who try to fight the aliens are subdued via psychic powers. After all, a deal is a deal. Over time, it can work out that a great plague wiped out all the humans that were not symbiotically attached to an alien, however the "survivors" are doomed as well, because their means of surviving the disease kills them upon reaching their 25th birthday. -- is there any interest in me expanding on this idea, or am I beating a dead horse? [Answer] I like the [nanobot idea](https://worldbuilding.stackexchange.com/a/29879/2113), but I'm not sold on the alien source. Let's toss out the aliens and look for a purely human motive to have something happen at 25. For example, a brilliant nanotech engineer sees the movie In Time and agrees with one of the ideas from it: people reach a physical and mental peak of maturity at 25. It's all down hill from there. So the plan is to freeze aging at 25. The first part of this is successful. Frankenstein (all the best reckless inventors are named Frankenstein) develops a method that allows nanobots to determine the age of any human with great accuracy. The next part doesn't go as well. The idea was to stop aging by repairing the naturally occurring damage to the cells and grow new ones to replace the most damaged. Unfortunately, rather than making just one replacement, it keeps on making replacements. This has much the effect that cancer does, plus it uses up all the body's nutrients. People can't digest their food fast enough to stay alive. The same section of code that was supposed to limit the cell replacement was intended to limit production of new nanobots. So the error existed in both and instead of a limited number of nanobots for experimentation, they reproduce as many times as they can. Only one made it out of the lab, but that was all it took. It triggers in everyone 25 or older and lies dormant in those who are younger. Since the young seem unharmed, they don't realize that they need to quarantine them until it is too late. Also, it is difficult to quarantine. They're nanobots, not bacteria. If they don't get proper nutrition/fuel, the nanobots hibernate until they get some. Everyone working on the experiments is 25 or older, so they all die. This gives you something like you want. There's a single event that kills everyone over 25. If you're willing to believe that the nanobots can accurately measure age that close, you can even get people dying exactly on their birthdays going forward. It's not quite instantaneous, but it is relatively quick. If instantaneous is necessary, you may be able to come up with a different problem with the process. Note that it's quite possible that the nanobots are more accurate if they've been with someone since birth. Then they just need to measure time since the placenta is disconnected. As a backup, they can still use whatever age measuring method to confirm. So the initial event may kill everyone older than 34, most people 25-34, some people 16-25, and no one younger than 16 (blood tests for age have an error up to 9 years; examination of teeth and bones may allow for additional accuracy). Once everyone who was alive at the time of the event dies (within 25 years), the more accurate method would be usable with everyone. [Answer] Xenqua isn't on Earth is it? These are aliens. So ... Xenquans expect to die in their 77th year. A few reach 90. A few die young at 64. Spot the pattern. Of course it is not universal. There are accidental deaths at any age. Here on Earth we have organisms that live precisely 13 years. Never 12 or 14. Related creatures live 7 or 11 or 17 years. They are cicadas. Xenquans have a built in 13 year timer started at conception. It triggers puberty at 12, which is rather more drastic for them than us. One very important thing that puberty does is to cause maturity of a gland which then secretes an inhibitory hormone. So the next time their 13 year timer ticks, they do not re-enter puberty. But later in life that gland weakens and their bodies go into total organ failure caused by the same mechanism that produces puberty the first time around. And now there is a plague which destroys this gland. Puberty at 12 years. Death at 25 years. Easy wasn't it? [Answer] ## Make the trait that kills by age 25 also convey greater fitness until death How is this going to spread in the population? If this genetic disease makes a carrier less fit than competing individuals then the disease will die out. However, if the disease dramatically increases fitness compared to non-carriers then in a few generations the entire population will have this trait/disease. It will be up to the author to decide what trait provides greater fitness: perhaps greater strength, greater resistance to poisons, greater intellect, brighter/flashier feathers (sexual selection)...the list is endless. The rest of the answer will assume human-like development and reproductive capabilities. In year [X], someone got this mutation either at conception or later by a virus...just like humans get genetic diseases on Earth. Personally, the virus approach seems to work best because a virus can spread through a population fairly quickly (days or weeks) while mutations at conception only effect a single person. There's any number of ways to make this mutation kill the carrier at or by age 25. * Maybe there's a metabolic by-product that accumulates to lethal levels by age 25. [Maple Syrup Urine Disease](https://en.wikipedia.org/wiki/Maple_syrup_urine_disease) is an excellent example of this in humans. * An auto-immune disorder that ramps up approaching age 25. * Mental health disorder, say deep depression that leads to suicide. As long as the mutation conveys greater fitness but at the cost of decreased life span, it should satisfy the requirements stated. [Answer] According to the 1970 hippie-fantasy movie [Gas-S-S](https://www.youtube.com/watch?v=DdVHWb0inos "Gas-S-S"), a human's neurons start dying off at age 25. A chemist came up with a gas that made that accelerated the depletion; so that a person ages normally, but when he reaches 25, he dies from the depletion in a short time. Would something like that work? The "hereditary disease" causes rapid neuron depletion, but only in people who would have that depletion normally? Also, see the episode "Miri" from the original Star Trek. [Answer] Here's some graphs: [![enter image description here](https://i.stack.imgur.com/Z99Ef.png)](https://i.stack.imgur.com/Z99Ef.png) [![enter image description here](https://i.stack.imgur.com/506vR.jpg)](https://i.stack.imgur.com/506vR.jpg) [![enter image description here](https://i.stack.imgur.com/RUhcb.jpg)](https://i.stack.imgur.com/RUhcb.jpg) Also think about their derivatives. Basically, when these things hit a certain level, the person dies. For example, maybe a parasite grows larger when more Testosterone is produced; when Testosterone starts declining, the parasite freaks out and kills the host. Similar explanations are possible. [Answer] There is a tropical disease called "Mal de Chagas", or Chagas Disease, caused by a parasite called trypanosoma cruzi. After an acute phase, with a very high survival rate, 20~40% of the infected get into the "chronic" phase, on which you start developing life-threatening heart and/or digestive disorders And die several years (10~20) latter, mostly form a sudden heart failure. A very non sciencey short explanations works like this: The parasites looks for the internal organs (principally the heart, and the digestive track) and just kinda lay there. Then the human's immune system goes and kills the parasites, but they also damage nearby tissue in the process. This tissue damage is what actually kills the infected person. The Chagas disease is transmitted orally (by eating food or drinking water where an infected bug defecated) or by blood. You could work with a similar idea. A parasite, that's found on their water/food source, and kills 25ish years latter. They contract the disease at early age, their immune system kills the parasite (or on a few cases they just die a couple of week after being born form the infection, but the Xenquans have yet to make the relation with their 25 years cap, and think that is completely normal having fever after being born) but their heart suffers some damage. They live a relatively normal life, but with some symptoms as irregular heart beats form time to time. Eventually, between 20 and 30 years latter they simply suffer a heart attack. Pros: * Its a non magic solution to kill everyone at ~25 years old * The sudden heart attack goes nicely with your initial idea of suddenly dying, and any rudimentary autopsy will simple result in "heart failure" Cons: * They would not simply die at 25. They would die somewhere between 20 and 30, sometimes even earlier, depending on the particular heart strength. But due natural selection, those of weak heart would not live enough to have children, so the average will be 20+ * They would also suffer form some symptoms, as irregular heartbeats form time time, and those symptoms would progressively worsen. I can't hardly think of a natural way that kills exactly at 25 years, and even human engineered ones also seems improbable. My example of Chaga's disease was the closest I could find EDIT: Since I don't know the effects of Chaga's disease on newborns, and I highly doubt that they are the same of an adult's symptom. You could make the parasite to be found on a particular water/food source, and that the Xenquans have an adulthood rite (which would be half of their life expectancy) involving said contaminated source. OR maybe they have something like beer, which only "adults" can drink, and thus they contract the infection at 12~13 and still get the ~25years kill (just make the parasite a bit more aggressive). [Answer] The mutation rate is abnormally high (at least compared to our own world). By the time a person is 25, they have accumulated enough 'noise' in their DNA that their organs don't continue to grow themselves according to the proper pattern. It could be caused by mutagens in the environment, or their planet's sun could generate more EM radiation than ours does. Pros: Not magic, and it could easily happen. Cons: It would not kill the person exactly at 25. Though, as AndraiROM noted: > > The problem with something like a disease, or radiation, etc is that the "disease" has no way of knowing when you turn 25. It's also highly suspicious that it doesn't seem to affect you at all growing up, but then suddenly you die on your exact birthday. It's ridiculous. > > > ]
[Question] [ I once ran across a question on this forum a few years back that questioned if mountains made out of diamond could reasonably exist. Ever since then I've been interested in the concept of diamond mountains on my planet and I designated a random desert, the Yyn desert which I had previously not written about as my diamond desert. The idea that I had at that time, and that I still hold for now, is that a series of short mountains in the middle of the desert over time eroded away into this desert of small diamond partials. Today I started writing about a location within that desert which prompted me to ask what a desert made out of diamond look like? I can't imagine that a diamond desert would be see through like glass. I'm thinking that the desert would be pure white. I'm guessing that would mean the desert would reflect an absurd amount of light, far more than just being all sparkly. I imagine maybe the sunglasses of my world may have been invented so people can traverse this desert. Aside from diamond, I have been considering glass as a candidate for this deserts composition. My planet has a history of failed alien terraforming. Perhaps the desert was turned to glass after an incident involving some kind of heat based technology that accidentally turned the sand molten? If all else fails, I suppose I could make up some fantasy substance for my desert, but that leaves me with my original question; If there was a mountain/desert made of glass/diamond-like material, would it be see-through? White? [Answer] ## like normal mountains and deserts, no it will not be see-through Mountains on earth are mostly made of quartz which is also transparent, are mountains see-through? impurities, crystal structure, fracture pattern, weathering, all of these will make it opaque. These pebbles are made of transparent quartz but simple weathering has rendered them opaque. weathered surface is irregular and rough microscopically, which makes it opaque. You need to polish a material or otherwise render it perfectly smooth for something to be see-through. Sand in deserts is also made of quartz often individual grains are transparent but the net effect is not much like piles of transparent ice crystals forming snow. [![enter image description here](https://i.stack.imgur.com/BTPGBm.jpg)](https://i.stack.imgur.com/BTPGB.jpg) Here is what a quartz crystal looks like. [![enter image description here](https://i.stack.imgur.com/nMcYk.png)](https://i.stack.imgur.com/nMcYk.png) Here is what a mountain made of quartz looks like. [![enter image description here](https://i.stack.imgur.com/xtUM5.png)](https://i.stack.imgur.com/xtUM5.png) here is what normal desert sand looks like under a microscope. Note each grain is transparent yet a desert made of sand is not. [![enter image description here](https://i.stack.imgur.com/GbjCc.png)](https://i.stack.imgur.com/GbjCc.png) for comparison this is what raw diamonds look like when washed and lightly polished, note again not transparent. [![enter image description here](https://i.stack.imgur.com/5M8pa.png)](https://i.stack.imgur.com/5M8pa.png) [Answer] Let's pursue this from a "realistic" perspective, first. Planets exist in geological time frames. That silica sand in terrestrial deserts didn't start out that way. Neither did your diamond deserts. Eons of time and erosion produced the sand. Let's start with deserts Silica is silicon dioxide. As mountains were ground down over millions of years, the silicon in those mountains absorbed oxygen to create the very stable silicon dioxide. We need to know this because it's our baseline for understanding what would happen with diamond and glass. Diamond deserts? Not really Diamond is just carbon. Carbon that's been subjected to high heat and pressure for those same millions of years, and then must be subjected to erosion for millions of years more. A planet with "diamond deserts" would be very old. But, what do you get? A lot less diamond, I suspect, than you're thinking about. What you're going to get is [carbon black](https://en.wikipedia.org/wiki/Carbon_black) (also known as carbon dust) with some of it siphoned off to create the gases carbon monoxide and carbon dioxide. Your deserts would look black. A very lovely black, though. At least as lovely as your space suit helmet will allow. I'm having trouble believing a planet with this much diamond would result in a breathable atmosphere. I would expect to find an unusually high number of diamond rocks, though. What would they look like? They'd look like the dull crystal rocks that diamonds in the rough actually are. You don't get sparkly prism colors until you cut diamonds at the correct angles, and nature doesn't do that (if it does, I suspect it's really rare). You can see a wide variety of rough, glassy, natural diamond rocks at [The Raw Stone](https://www.therawstone.com/collections/raw). OK, so what about glass? Glass is even worse. It started as silica, was heated to a liquid and then re-poured into a convenient shape that we call "glass." What do you get when you erode it over millions of years? Yup, silica. When you walk in sand dunes today what you're walking on is your glass desert. Glass, silica... same thing. OK, ignore the desert, what about mountains? First, it's important to understand that mountains are anything but homogeneous. Even volcanoes, which have a very high percentage of obsidian and other volcanic rocks aren't just one thing. If you're imagining a single huge mountain-sized diamond, that's not what you'd have. A "diamond mountain" would be one that's predominantly made of diamond, in a variety of formations and sizes. To the best of our knowledge, nothing grows in just carbon black, so it's a good thing that your mountains also have other materials that eventually combine to create a real soil. A glass mountain simply isn't realistic at all. I can't imagine how it would form naturally. You get small amounts of obsidian glass from volcanoes or small amounts of glass when lightning strikes silica, but mountain-sized amounts? Even predominantly? I can't see how it can be done. Even if it could, glass is very brittle, so it's hard to see the mountain staying a mountain very long, and if it appeared in the high heat/pressure conditions that form diamonds, it would melt. OK, no mountains, no deserts... what if we toss reality to the wind? Let's invoke the engineers of Magrathea and just make mountains and deserts of diamond and glass. Who cares if they would only last a short while? Our world is brand-spanking new off the assembly line and orbiting a sun just like Sol. What would they look like? If those engineers didn't cut any facets into the diamond mountain, it would look like a gigantic piece of what you saw when you clicked on The Raw Stone link, above. But if the engineers took the time to chisel those mountains so that facets were everywhere, what they'd look like after you put some sunglasses on would be a brilliant mind-blowing consciousness-expanding shower of every color you can imagine. It would be as breathtaking as it would be a danger to aerial navigation for hundreds of miles in any direction. I'd buy a ticket to see it. The diamond deserts if uncut would be a milky color. Note that the many colors of raw diamonds come from contaminants. We're talking about the pure, undefiled beauty here. But if they were faceted... I doubt even sunglasses would save you. The desert would be a navigation hazard to space-faring vehicles. At least that's my opinion. A glass mountain would be more translucent... but glass isn't perfectly light conductive. Looking at the mountain would give one the feeling that there's a lot of depth. It would be similar to looking into a deep lake of really clear water. You can sense that the water goes down a honking long way... but you can't actually see it. What you would "see" would be milky as the light would be refracted across the spectrum. But a glass desert would be similar to a faceted diamond desert, but not as intensely brilliant. And unlike the diamond desert (in my opinion) the glass desert would be sharp. Wear tough shoes. [Answer] ### Compare with water ice Water ice is known for being transparent. However it doesn't take much to get it less transparent such as a bucket of ice cube. Such as most sheets of ice on puddles during winter. Black ice vs white ice on lakes. Most ends up being white ice due to snow, impurities, faults/fractures, inclusions, bubbles all contribute to making ice less transparent and more opaque. #### Antarctica. Greenland Large scale example is Antarctica or Greenland. Those are mountains and plains made of water ice. These represent the best case scenario of being mostly pure compared to other possible transparent materials, due to being formed from precipitation. ### Minerals from crust. Most other transparent materials will form from mixes within the crust. If the are forming from mixes they will rarely if ever transparent in bulk. So transparent minerals such as diamond, corundum, silica, salt(NaCl), sucrose or etc. could form mostly pure mountains(given the right process). However when broken down into sand sized particles would resemble white sand beaches if mostly pure. Eg several white sand beaches are made of silica that if in large pure crystals would be transparent. But for most part will look like rock/sand that we can see on Earth or like other mostly solid bodies in our solar system. [Answer] You have a problem that none of the other answers have addressed: Let's say you have this diamond mountain range. How it got there is not relevant, let's just assume it exists. You say that it eroded down to a diamond desert. This erosion presumably took place on geologic timescales, because eroding a mountain down to sand takes ridiculously long. (source: look at all the mountains we still have on Earth! They've been there for tens of thousands of years at the shortest, millions to hundreds of millions for most.) But there's a problem with this: Under ordinary temperatures and pressures (e.g. on the surface of an earth-like planet), diamond does not remain diamond for more than a few millennia. It's well known among chemistry students that graphite is the lowest-energy allotrope of carbon at standard temperature and pressure, to the point that it's literally a [textbook example](https://chem.libretexts.org/Courses/University_of_Arkansas_Little_Rock/Chem_1403%3A_General_Chemistry_2/Text/18%3A_Entropy_and_Free_Energy/18.01%3A_Spontaneity_and_Energy_Transfer) of a very slow spontaneous transition. Your mountain would turn into a mountain of graphite before it even had time to become a desert of diamond. [Answer] Captain W.E.Johns (the man who wrote the Biggles books) also wrote science fiction in the fifties. In his ['Now to the Stars'](https://archive.org/details/jntts/page/n45/mode/2up) there was a glass planet. There is a picture on page 40 where they get a view through a clear section of glass down to the planet's molten core. This is pretty unlikely - ordinary glass is rarely pure enough to see through more than a foot of the stuff. It took a lot of fancy manufacturing to get fibre optics to get to kilometre distances. Water can be that clear, though. [Answer] For a moment, we skip the process of forming your diamond deposits. This is chemically hard, but not impossible. Diamond is able to [BURN](https://www.youtube.com/watch?app=desktop&v=oS6fWwpI1A0) in a human-breathable atmosphere. Just like coal, it has somewhat higher calorific value than coal and will still produce the same carbon dioxide when burned. It will readily burn in an atmosphere containing some oxygen even it is not really breathable. Your desert made of diamond sand will burn down in an immense fire after the first source of ignition (a lighting will do). This is how coal deposits exposed to the surface end up burning down. On the other hand, if your diamonds are this much abundant in your world, they may as well fuel the industrial revolution just like our coal did. ]
[Question] [ These humans would be 10x smaller than us, around 16-18cm tall, just divide by ten on our current heights. If we're small, that would mean animals are 10x bigger than normal. Keep in mind that puddles would seem like floods for them and a normal flood would be a tsunami. As an example, a housecat would seem like its 5 metres tall standing on both legs. Small humans are stronger relative to body size so let's say there are no limitations on their form and style of architecture right now. I just need some ideas! Thank you [Answer] Tunnels Tunnels are a great way for small mammals to not get eaten. Our primate cousins who are the sizes you describe live in trees but I must say it seems like a lot of things eat them. I would pick tunnels over trees. There are some animals that can come down tunnels to eat whatever is in there - I am thinking mostly snakes. The thing about tunnels made by humans is that humans have invented doors, with holes to look thru. If you look thru and it is a snake, don't let it in. Poke it with poison spears thru holes in the wall. Re weather: nothing beats bad weather like going underground. It is always nice down there. Kinda dark, though. You will need creative illumination options. [Answer] Burrows. Small humans would benefit from the square-cube law in so many ways -- they can lift (or dig) more relative to body weight, the chambers they produce are much less likely to collapse, and collapsed material falls a much shorter distance. Seams of desirable material for burrows are relatively larger. A woodchuck can make a good living this way, but these are not woodchucks ... they can still manufacture rail systems to move debris out of tunnels, engineer ventilation and escape shafts, and study the local hydrology to ensure their tunnels are safe from any flood. They can cap residential neighborhoods on the outside with strong clay or pottery roofing to prevent even the worst storms from taking a toll. Though trees might seem a challenge, Orcs of all species have little trouble chopping redwoods, so I think your Dwarves could modify most local landscapes with ease. If warm blooded, their nutritional needs would be more than the 1/1000 of human that you would expect by size, due to greater atmospheric cooling. Their [heart rate](https://www.merckvetmanual.com/circulatory-system/cardiovascular-system-introduction/the-cardiovascular-system-in-animals) and metabolism would run a bit faster. Still, kittens [weigh 2 pounds and may need 162 kcal/day](https://be.chewy.com/how-much-to-feed-your-kitten/) - that is still bigger than your Dwarves, and kittens need to grow! So Dwarves could do all the intellectual work, research, philosophy, invention of at least dozens of humans for the same caloric intake. This suggests very well planned building projects. Tree dwellings. Dwarves would have much more trouble approaching a forge, since they have a thousandth the heat capacity of humans. It would take a great deal of ingenuity to reach the level of technology for industrial projects and hence metal buildings outdoors. However, all the arboreal developments of fiction would be available to them - essentially, burrowing in trees. While they would need to fear falling off in the wind, they are also small enough to glide like flying squirrels. Some relatively easy textile technology might have them gliding in no time. They don't have the wing muscles of birds, so they could not fly that way for long, but they would be clever enough to find places where they could catch updrafts and hang glide far more effectively than any human. Animal dwellings. Courageous nomads might see merit in building colonies aloft some types of grazing animals, since they can still domesticate them with the usual expedients of food and gentle correction. Zebras and even elephants might give too much excitement, but a Galapagos tortoise might make a fine mobile dwelling. A little army of tame turtles, rewarded for their efforts by sustainable agriculture at scattered farming and gathering sites, could keep the Dwarves comfortably mobile for a long time. [Answer] ### Pretty minor changes - humanity could still thrive with essentially current city design. So there are a few ways to answer this all with subtle differences - did humans start this small? Did everything else start this big? Did everyone wake up one day and the world was suddenly 10 times as large? The first 2 possibilities "Tunnels" are the answer (with square cube law giving differences between the two). I'm going to answer the last one - everything that is a human or part of human society suddenly got 10 times smaller overnight. "Honey - I shrunk the city!" So starting with the current world; assuming: * All animals are suddenly 10 times taller relative to humans * All weather events are 10 times more intense. Instead of 25mm of rain overnight, it's 250mm of rain. Tornados and hurricanes have 10 times more power. (Not nesc 10 times faster wind speed). Our existing architecture and city building styles should be able to handle this passably well. Cats and Dogs are tiger sized, and tigers don't defeat cities, and we can control them when they attack. Mosquitos are bird sized, and we can handle birds. Ants are the size of rats and we can handle rats. Rats will be the size of cats and we can handle them. A spider that comes up to your knees will be terrifying, but manageable. There will be some damage from large pets destroying the neighbourhood around them, but I'd suspect we can manage it with our existing weapons. Especially in parts of the USA with strong 2nd-amendment culture and everyone's carrying assault rifles, and especially as most of those animals are former pets which were tame before. Cows will be an issue, but they'll starve to death without us looking after them. I suspect we'll be able to scale up our meetworks to handle a 10m cow within a few months and learn to redomesticate them again. Large animals like elephants and tigers will basically become absurdly large. These will need basically military campaigns to defeat if they choose to attack. However I don't think this will come up that often - I can't see an elephant stomping the suburbs godzilla style for the same reason I don't stomp on lego houses barefoot. Some subtle changes will be needed: * Storm drains will be larger, as your basically building for a worse peak rainfall environment. Gutters will be larger, downpipes will be larger. + My city once got 11mm in 2 minutes, and we need to design buildings to accommodate that, now it's going to have to survive 110mm in 2 minutes. * We'd adjust building codes for stronger relative winds - hurricane straps in the roof, roofs anchored to walls stronger, walls anchored to foundations stronger, those sort of things. + Tornado shelters would be more common, and used more often as winds strong enough to risk a building would occur more frequently. * The biggest animal threat will probably actually be birds. They won't be able to swoop us away pterodactyl style but could do some damage in hand-to-claw combat. Human weapons will kill them, a handgun should be suitable defense. + Eventually we'd probably set up netting to keep streets bird-free. * Stray cats would also be a problem and quickly rack up a kill count, but if we can handle tigers when they escape from a zoo, we can handle stray cats. A handgun may not have enough stopping power to save you from injury but could definitely give fatal injuries. * Walls (and floors and roofs) of new buildings would be thicker than what you'd expect from a simple resize. Essentially square cube law at work. All new homes would need to be double bricked or equiverlant. [Answer] There is a great children's book by Wil Huygen called [Gnomes](https://en.wikipedia.org/wiki/Gnomes_(book)). It explains the answers to your question with [rustic-looking](https://tvtropes.org/pmwiki/pmwiki.php/Main/BambooTechnology) technology. Basically, brains beat brawn even at this scale. [Answer] ## Density, greenhouses, and rocket launchers: Assuming a very small but highly intelligent mammal (we'll call them people, but they might not look exactly right), your people will favor warm climates where temperatures will be warm. Colder temps will be doable, but more challenging. Small size and the danger of predation suggest that they might tend towards small, dense, multistory dwellings (likely single buildings), as building material will compensate better for the relatively small size, height, and load-bearing requirements of small people. Multistory structures surrounded by walls like fortified cities would also be easier to defend from kaiju like bears, lions, and tigers. Your people might very well be agoraphobic, with open spaces representing threats, and enclosed spaces representing safety. As they increasingly moved into cold climates, structures would likely be even denser, with thermal properties integrated into town/building designs. If I were tiny people, I'd gradually wall in and fence EVERYTHING, including netting and screens to keep out killer bugs and the like (a bee sting or spider bite could be lethal). Agriculture might very well be all in greenhouses or netted-in enclosures to make open spaces safe (eagles and other birds would be very real threats). Entire "cities" might be enclosed in huge greenhouses to extend the growing season, provide physical protection, insulate the community with an outer structure, etc. Tents could also provide a similar function, and a "city"-sized tent is not unreasonable on this small scale. Unfortunately, I suspect that your people might have a rather un-environmental view of other life forms. Even non-predators will likely be huge and terrifying. As soon as they have the tech to do so, they will likely try to eliminate these threats from the environment. Given the suggested tech level and enhanced structural strength of a lot of materials, I envision dirigibles (possibly quite large and city-like to compensate for winds - how 1920's Futurist!) and airplanes bombing and strafing animals (think King Kong). Armored vehicles (like small tanks) could have guns mounted on them and fire quite satisfying projectiles at anything threatening. Functionally, guns would be more like cannons, possibly fired from bunkers and concealment. Your tiny people could be quite fearsome hunters in their own way, and each kill would provide mountains of meat (to be hauled away by tiny trucks or huge pack animals). Any animal of sufficient strength and stability to carry a cannon and allow one to be fired from it's back would be extremely valuable (bison? Low heads to not interfere with firing arc). A good faithful hound might be a valuable animal for your people. Big enough to ride, fight, and haul goods (including cannons), yet loyal and docile enough to be trusted. If your people WERE hunters, then the ready supply of meat would assure food for dogs as well. A kennel would be an essential part of every community, even as vehicles increasingly gain traction (pun intended). You might even be able to design a gun or mortar that could be mounted on a dog and fired like a cannon, and you could certainly haul a "hand" grenade that could be dropped like a huge bomb. Rockets were invented by the ancient Chinese, and these would be significant force multipliers. Gyrojet projectiles (once invented, and the pressure to do so would be large) could take up the functions of guns, but it would look more like people carrying RPG's than rifles. No recoil, though, as they are basically miniature missile launchers. Small vehicles with guns on them could work as well, like tiny tanks. They wouldn't need to be terribly well armored if they mostly dealt with animals. Various kinds of shaped explosives could fire flechettes or blast like a shotgun shell fired from a tiny mortar. Warriors & hunters in this society would be armored. The lower force of most attacks, need to defend themselves from animals, and higher capacity to support weight per unit volume would mean armor would be much more effective for longer against more modern weapons. I envision the armored knight with a force-multiplying lance riding a nimble war dog would last well into the era you are talking about (in the same way cavalry was enduring into the 20th century despite increasing challenges). [Answer] Depends on your tech level. Paleolithic Humans would take advantage of natural caves and holes in the ground for shelter. Neolithic Humans would primarily dig warrens, and maybe build nests in trees. A lot of macrofauna such as saber-toothed tigers and giant sloths will have avoided extinction at the hands of humanity. Most will probably start avoiding human settlements, since it'd take them a lot of effort for a small amount of food. Our true predators would include snakes/ferrets, which could infiltrate our tunnels, badgers/bears, which will destroy our homes, and birds of prey, which will opportunistically grab any human in the open. Bronze Age is where the really interesting stuff begins... Bronze-making requires trade networks stretching thousands of miles, since Tin is very rare. I can imagine ships that are practically floating cities in their own right. On land, imagine if the Pyramids were basically giant termite mounds... Civilizations would clear the best farmland of natural predators with traps and "siege" weapons, and by killing them young, but the more hostile biomes would remain "monster"-infested. (Not to say that humans wouldn't still live in such places, but they'd be considered savages by "civilized" people.) Iron Age/Industrial will probably blur together, since even prototype steam engines/clockwork will be more powerful than slave labor and easier to manage than beasts of burden. I can imagine "landships" that are basically just self-propelled all-terrain wagons, which use thick wood for armor and possess miniature cannon. Such trade would be lucrative, but run the risk of encountering massive beasts and ambushes from brigands. Modern buildings will basically be scaled-down Arcologies; skyscrapers would have thousands of stories and could effectively be cities unto themselves. Public transportation will be more popular than miniature cars, although miniature helicopters for transport between buildings will be common. Battery power will be much more prevalent than fossil fuels. Large predators will be exterminated by people in airplanes/airships unless conservation measures are taken. Unfortunately, it'll take us much longer to develop personal computers and spaceflight. Future is an unknown; however, it'll at least be easier for us to make a humungous (by comparison) mecha. ]
[Question] [ I'm looking for a few weapons which I can use to attack a planet from orbit. I'm not looking to destroy it or make it uninhabitable, just wreck a few things until the occupants stop launching anti-orbital missiles. [This question](https://worldbuilding.stackexchange.com/questions/22499/whats-the-most-efficient-way-to-destroy-civilization-from-orbit) had some good answers, but those were with an advanced civilization and the goal of killing everyone. The technology level I have in mind is basically what we have now, but maybe a few decades ahead. Smaller nuclear generators, a rather small space fleet, and stuff like that. I know we have some weapons already that can hit earth from space, like [ICBMs](https://en.wikipedia.org/wiki/Intercontinental_ballistic_missile). I've also heard from somewhere that there might be tungsten rods that we can drop from space. I can't remember where I heard that from though, so it might be nothing. What are the most realistic/plausible/scientifically possible ways to attack a planet from orbit without killing everyone or making it uninhabitable? If you can, find a weapon for different fallout levels (house, city, country, and world), so I don't have to be wasteful when destroying rebels. [Answer] Kinetic Bombardment (AKA "rods from god"): Kinetic bombardment (<https://en.wikipedia.org/wiki/Kinetic_bombardment>) takes advantage of the Earth's gravity well to drop things on people from space. Sounds simple and primitive, right? Well, much like a meteor (in fact, at it's simplest level, it IS a meteor) gravity does all the hard work and you just need to aim your mass at the planet and keep it from burning up in the atmosphere. If you aren't fussy and don't car too much about casualties, asteroids are a cheap, non-radioactive alternative to nuclear weapons. Just grab one and aim it. With an additional generation of sophistication, the aiming should be the simple part. Jerry Pournelle <https://en.wikipedia.org/wiki/Jerry_Pournelle> actually championed the development of these systems before becoming a successful sci fi writer. I think project Thor is what you are specifically referring to. If you have the mass in orbit, and and the guidance to steer it, you have one of the deadliest weapons in the world. The hard part is getting the mass in orbit, but if you are already in space and can exploit asteroids, that's not a problem. Small problem? Small projectile. Big problem? Big projectile. Losing the war? Drop Ceres on Earth and come back in a few thousand years when the climate recovers. [Answer] Kinetic Energy Weapons The tungsten rods that you've heard about are what are generally termed 'kinetic energy weapon', or to use the slang term 'Rod from God'. Basically, you just get a really heavy metal rod (tungsten works fairly well, though there are alternatives), fire it into the atmosphere, and let kinetic energy and gravity take over from there. All the power of a nuclear bomb with none of the fallout, very difficult to detect and very difficult to deflect, and not to mention that all it requires in the way of manufacture is getting the weapon up there in the first place - no need to fool around with uranium enrichment plants which can be bombed / blow up in your face. The US government has considered the possibility of placing a satellite in orbit with just such a weapon code-named 'Project Thor'. [Answer] Broadly, there are three categories of weapons. Directed energy weapons which deliver energy to the target, kinetic weapons which deliver mass to the target, and ordinance weapons which deliver a payload to the target. Let's break it down: * Energy + Lasers/Masers: Laser weaponry is currently on the cusp of being integrated into the modern military. Already some navy ships are equipped with lasers, albeit mostly for point-defense roles against drones and incoming ordinance and not offensive roles. In the near future (<10 years) these laser systems will also find their way into land-based applications, although still primarily in defensive roles. Extrapolating into your future setting, I don't think it would be unreasonable to have an orbital laser which is capable of striking targets on the ground or in the air. Primarily, this would be a precision weapon as the beam needs to be quite small in diameter. It could be used to opportunistically take out exposed and underarmored ground targets or aircraft, but would not be usable for causing widespread destruction. + X-Ray: During Regan's "Star Wars" program, nuclear-pumped X-ray laser weapons were considered. These consisted of a nuclear bomb with long metal rods to lase the x-ray radiation. The advantage is that they are very powerful and destructive and could theoretically create quite a powerful beam of radiation strong enough to melt through obstacles. Unfortunately, this type of weapon is not very efficient for sub-atmospheric targets because the atmosphere eats away at the beam's strength and it is a "one-shot" weapon--after the nuke goes off, the weapon is destroyed. This type of weapon would be cheap and effective against space-based or high-altitude atmospheric targets. * Kinetic + Rods from god: The US military has actually considered this one but deemed it too expensive at the time (I find it likely that it will eventually be built though). The concept is simple: large kinetic impactors are launched from orbit to strike ground targets with sub-meter precision. There, the sheer speed and mass of the armament causes massive amounts of localized and non-radioactive damage. This concept is liked by the military, because unlike nuclear weapons, RfG can serve a tactical and a strategic role in contrast to nuclear weapons which are exclusively strategic. Furthermore, a country could get away with launching a RfG without escalating the conflict to nuclear levels. Destruction-wise, these compare well with conventional bombing attacks. A RfG could be used to take out a single tank, an entire military compound, or a bunker that's deep underground. + Repurposed asteroids: Provided you're willing to play the long game, it is possible to shift the orbits of near-earth asteroids so that they impact at a specific time and location. Doing so would require months or years of preparation, and it would probably be hard to keep it stealthy. Still, if you're able to coat the asteroids in stealth-paint or whatever, they provide a good alternative to nuclear weapons because while they have the destructive potential, they don't have the radiation. Unfortunately though, the explosions caused by meteors most likely relegate the into the "strategic weapon" category as it would be difficult to avoid civilian casualties. * Ordinance + Conventional warheads: Just like ICBM's can be launched from the ground, you could launch them from space too. These could be equipped with all sorts of munitions ranging from simple high-explosive to war-crime cluster mines. This probably won't be very common as it would be much simpler and cheaper to deploy these weapons from drones or sub-orbital weapons platforms. + Nuclear/WMD warheads: Not much to say here, but nuclear, chemical, or biological weapons are almost exclusively strategic because they do not distinguish between military and civilian targets. Nuclear weapons in space ship-to-ship combat might be useful, but in terms of leaving the planet whole and habitable, these probably won't be used for bombardment. + Combat robot payloads: Military forces around the world are hard at work on so called "canister drones" which are essentially drone-swarms-in-a-box. The idea is that you drop a hundred or a thousand drones from an aircraft or launch them out of a van or whatever and then they go and cause mayhem. These drones could be equipped with small explosive charges, firearms, or other weaponized payloads. Theoretically, large amounts of combat drones could be dropped from orbit ("on-demand drones") but it's likely that these could be delivered to the target area without needing to go to space first. Damage potential for these is variable, but mostly suited for surgical strikes. [Answer] [Here](https://www.rand.org/pubs/monograph_reports/MR1209.html) is a real-world report on space weapons by the RAND Corporation. They do consulting work for various US government agencies. They found that ground-based weapons are cheaper for most purposes, but then they assumed a ground-based industry. * Yes, tungsten rods are a [viable concept](https://en.wikipedia.org/wiki/Kinetic_bombardment). To make them practical one would have to preposition them in orbit and deliver enough delta-V do de-orbit them. Lifting them into orbit becomes "free" if the attacker arrives from outer space. Simply leave them up there when the ground troops drop. * In most cases a nuclear warhead will be more lethal than a kinetic warhead, so replacing the tungsten with nukes is also an option. * Laser weapons may be feasible. Again, there is the cost of lifting them into orbit, and again that is a non-issue for attackers from space. [Answer] Frame Challenge: # Don't attack the planet. Your goal is: "the occupants stop launching anti-orbital missiles". Cool. Set yourself up in a high orbit above the planet. Hit a bunch of satellites with normal, garden variety missiles. Done. You've just set off [Kessler Syndrome](https://en.wikipedia.org/wiki/Kessler_syndrome). The satellites you've blow up have scattered into hundreds of pieces, which in turn will hit other satellites, breaking them into smaller pieces in an endless cascade. LEO has become a rotating, orbital shrapnel cloud. No missiles are going to get through. It's now impossible for the groundlings to put anything in space at all. But you can go get up and down. You're in a high orbit, with heavy (but basically "modern") military hardware. You can use high energy lasers to punch a hole in the orbital death cloud, and go down to Earth. The chaotic orbits means that hole will "heal" quickly, but for a while there was a window. The groundlings can't do this since: * The goal of shooting a laser at the cloud is to push the pieces into the atmosphere, not destroy them outright - shooting up doesn't work * Atmosphere absorbs laser energy anyway, so Earth bound lasers can't make it to space If the density of the cloud gets too low, you can always insert more shrapnel whenever you want. Blown up asteroids are probably the cheapest option for more mass. You now control all orbital launches and landings, and have achieved your goal. Congratulations. [Answer] Since we are talking about technology only slightly better than our current ones, I'd say explosives are exactly what you're looking for. The fact that you're shooting from orbit doesn't really matter, since you are looking for the effect on earth. Sure it would require some adjustment to the weapon delivery system, but the weapon per-se would be the same as you would use if it dropped by a plane. 1. Let's begin with small targets: houses. Hellfire missiles are probably your best bet. It's what we currently use in drone strikes. They are great for smaller targets. 2. Cities: you have a few options here. If you only want to target a specific city in the world (or even a few), then I'd say a nuclear device is your weapon of choice. But if you want to destroy hundreds of cities, then you might want to avoid to deal with radiations. Carpet bombing would be best. It's messy, but also pretty efficient, considering you're not looking to destroy something too specific, but to level the whole town. 3. Country: I'm not entirely sure what you mean here, but I'd assume destroy both cities and population. If that's the case, I would go with carpet bombing for the cities, and MOABs (Mother Of All Bombs) for the country. MOABs are very effective against soft to medium surface targets in covering in large areas, and even more in contained areas. That means you could easily destroy large areas of a country with it. Not technically a weapon, but hacking could also be an option here; destroying a country's network, taking control of their defences, electrical grid, and so on, can cause serious damage and might push them toward surrendering. 4. World: Right now there isn't a weapon capable of "destroying the world" (as in killing everything on the surface) without making the world inhabitable. Nukes would do the job, but as said above, it would make the planet a no-go zone. If your goal is to kill everyone, without destroying the environment, then I'm sure some genetically engineered virus might do the job (possibly more than one). Bioweapons are currently not allowed, but then again you're destroying the world, so who's gonna stop you? A few things I'd like to mention: * Most of the world runs on a few basic supplies, with oil, gas, and coal being the most commonly used for energy. Considering oil and gas mostly come from few places in the world, making those spots inhabitable could do some serious global damages. * There have been rumours of a "nuclear torpedoes" being developed by Russia a few years ago. The idea was detonating it off the coast of a country as retaliation for a second-strike (as in, Russia strikes first, Country strikes back, Russia uses the torpedo). It is thought to be extremely destructive, provoking a radioactive tsunami. That means having the destruction of a tsunami, plus making the whole area uninhabitable due to radioactive residue. * EMP weapons would allow you to deal an incredible economical and logistical damage to a country, without doing much of physical damages (assuming you don't target a nuclear reactor), but as far as I know there aren't EMP weapons that cover large areas yet (closest thing would be to detonate a nuke, but that defeats the point). * Targeting food supplies or water supplies is also a great way to deal damage to a single city or a country, but if you're against a whole world it becomes less and less effective. [Answer] I'll write some fiction and then describe weapons. Some country or country on the planet has started the long, slow climb to becoming a [K-level-1 civilization](https://en.wikipedia.org/wiki/Kardashev_scale#Type_I_civilization_methods) by exploiting space. Doing this in the next few decades is economically crazy (the ROI is really, really negative for a long time), so I'll assume the nation has aligned around a religious requirement to move civilization to space. To do this, they started building a self-reproducing manufacturing base in space. The first problem with space is that it is expensive to get there. So if you can get materials in space and use them, they are going to be insanely cheaper. Solar powered ion tugs were sent to get high metal asteroids. Decades of effort was put into building vacuum forges capable of refining the materials found. This provided bulk. Simply insane improvements in 3D printing, and these bulk refined materials, permitted printing 3D printers with reasonable fidelity. These were then used to print further forges and more ion mining drones, which produced more raw materials. All of this is automated or telepresence friendly. But for religious reasons, the nation wants humans to live in space. So settlements are built, and many many people die. There is some modest conflict by rogue states and terrorist groups, so small amounts of defence tech is also included in the settlements (point defence drones and the like). After many decades, there are some non-horrible rotating habitats with organic life in them. They are leaky as hell, so they rely on a constant stream of new volatiles from asteroid mining past the "snow line". ... In this case, the best weapons that such a culture would have are the asteroid deliveries. Drop medium size rocks on the planet. This lets you exploit the solar orbital energy of the asteroid and convert it to delivered [KE](https://en.wikipedia.org/wiki/Kinetic_energy) on the ground. It is a long-delayed attack, but the energy amplification is really big. Traditional attacks also work from orbit. You have line-of-sight to everyone, if a bit of air in the way. Just build cannons and shoot stuff down. Those cannons can be drone-controlled. Defense against counter attacks is going to be hard. You might have to resort to nuclear interceptors; someone shoots a missile at you? Drop a nuke on it. It is plausible that the amount of uranium easily available in asteroids is probably higher than the Earth's crust, and nuclear reactors are a plausible source of power generation for a space civilization (especially for mining past the snow-line). (dumping heat is going to be as big a problem as making energy for space civilizations, which makes them less practical) The book The Moon is a Harsh Mistress has another idea; launch rocks from the Moon. You can convert the KE of getting out of lunar gravity well into the KE of falling into Earth's gravity well. That is a modest amount of amplification. It suffers from a single point of failure problem; a launch facility on the moon has to deliver energy fast to efficiently get it off the Moon, which makes it a target. Asteroid weapon launchers can be slow, and most of the heavy lifting can be done with a portable drone that pushes the asteroid, then detaches (leave a small engine on it for final aiming). "Rods from God" have the problem that rods are not stable (making them not-tumble is going to be hard), deorbiting requires a lot of energy, wind resistance is really strong. If you rely on wind resistance to deorbit, your orbital energy is wasted on the atmosphere. And your "rod from god" is a lot like dropping a rock from a few 100 feet up. I mean, it hurts, but not that much. If you don't rely on atmospheric braking, then you need to put almost all of the KE of impact into the orbiting body to get it to stop orbiting. [Answer] Most plausible near-future weapon systems to wage war from orbit: # Nukes delivered in ballistic missiles Against: City or large military/industrial complex * Simple * High yield # Ballistic missiles with conventional explosive payload Target: Small military base/factory Proven technology, but a lot less cost effective than the nukes. But also less investment required. # Drones Target: Individuals/vehicles Dropped in (non-reusable) re-entry vehicle (glorified heatshield and some parachutes). With drones as small as possible, just capable of carrying the required weapon system. Plausible weapons: * Missiles (armored vehicles/small buildings) * Machine guns (potentially electronically ignited/no reloading required). See Metal Storm. * Multiple small "Suicide drones" against lightly armored targets # Microwave cannon Target: Unshielded electrical installations, possibly individuals Large amounts of electrical energy and extensive orbital infrastructure required. Firing rate limited by energy availability and (waste-) heat management. Possibly low orbit required (polar orbits offer good global coverage) to hit hard enough. Could possibly completely destroy electrical infrastructure (transformers) on a global level in a short time, but would otherwise be more surgical/terror inducing than a device of mass destruction. # NOT plausible: Dropping kinetic penetrators from orbit This is an exceptionally stupid concept. Consider: Everything you want to drop you have to get there first-- this means lugging tungsten projectiles from somewhere. Might as well load the vehicle transporting your projectiles with explosives and send it towards the ground. Asteroids Same as the above-- anything worth dropping will require so much fuel to get in a collision orbit, that you might as well drop that fuel on target (or nuke things instead). This is even more impractical because it will take YEARS to actually hit (because planets typically clear their orbit of any viable candidates and you would have to fetch asteroids from half-way to Jupiter-- really impractical). I'd advise you to play [Kerbal Space](https://www.kerbalspaceprogram.com/) to get an intuitive understand of orbital mechanics (for science, of course ;) [Answer] OPTION 1) Temporarily destroy the ozone layer "The ozone layer absorbs 97 to 99 percent of the Sun's medium-frequency ultraviolet light" Therefore, deploy a cloud of CFCs into the upper atmosphere. After a few weeks most of the lifeforms on the surface of the planet will begin to die due to having 30X to 100X more UV exposure. After that, deploy another chemical to clean up the mess. You don't have to wait for everyone to die, you just have to wait until they give up. OPTION2) Block out the sun with a dust cloud. Deploy a cloud of dust that orbits the planet at the edge of the planet's atmosphere. You don't need to completely blot out the sun, just dim it. The dust will block enough sunlight that the weather will start getting very cold. Once that happens the inhabitants will run out of food or freeze within a few months. If the dust is deployed low enough, then atmospheric drag will cause it to naturally de-orbit itself a few months later. You can control how long the cloud stays up by controlling the initial deployment height. OPTION3) Block the sun with a giant space blanket Position a large circular space blanket between the sun and the planet. The diameter of the blanket needs to be similar to that of the planet. If the blanket were 1 mil thick, had radius of 4000 miles, and had a density of 1g/cm^3 (similar to plastic) then it would likely weigh around 3 billion tons (or 30,000 aircraft carriers). Therefore the key to making this work is to find some very lightweight materials to make it from (perhaps woven carbon nano-tubes?). [Answer] Both @Dragongeek & @Mr\_Bober have a useful list of ideas. Both exploit the fact that a planet attacked from space really has no "rear area": the front is above the inhabitants' heads, with nowhere truly good to run & hide at. Any such attack, with the goal of conquering a planet with minimal damage to its inhabitants, would run pretty much along the lines of the following: 1. Put space fleet in visible orbit around planet; 2. Drop a few bombs, "rods from God", or other destructive devices here & there on the planet; 3. Explain to the inhabitants you have more of these packages, & demand their surrender; 4. Repeat steps 2 & 3 until they do surrender. (Yes, this is roughly the same tactic the US employed in WWI against Japan. The alternative was an invasion of the Home Islands (Operation Downfall), which would have resulted in many, many more casualties. Sorry, a massed interplanetary version of D-Day would be a worse choice for both sides.) After the planet surrenders -- on terms or unconditionally -- the real challenge starts. Any invasion fleet will only transport a finite number of occupation troops. (Let's say as many as 2-300,000.) The planet will easily have 100 million + inhabitants, the overwhelming majority determined to resist their new alien overlords. Your occupation force will need a plan of how they will maintain control over the planet, determining which carrots & sticks you use. (Unless the inhabitants have a warrior ethos where surrender is worse than death, & the shock they have surrendered destroys their ability to resist.) [Answer] Cyber weapons. No need to resort to physical weapons in this situation. A concerted cyber attack should be able to bring any advanced civilisation to its knees without necessarily killing anyone or destroying anything; and that surely work in advance civilisation would be aiming to do with salt force [Answer] Sun Gun! Sun Gun has a lifetime membership to the orbital weapons club! [![sun gun](https://i.stack.imgur.com/k9TVm.jpg)](https://i.stack.imgur.com/k9TVm.jpg) <https://www.damninteresting.com/the-third-reichs-diabolical-orbiting-superweapon/> > > What interested the Nazi scientists, however, was his suggestion that > a specially engineered 100-meter-wide concave mirror could be used to > reflect sunlight into a concentrated point on the Earth. But whereas > Oberth’s design had peaceful intentions⁠—to use the intense heat to > produce electricity with steam turbines⁠—the nefarious Nazis > envisioned a colossal heat ray which could vanquish humanity. > > > The Sun Gun concept was essentially a scaled-up version of Archimedes’ > ancient and oft-debated “Death Ray.”... > > > Yes, yes, the environmental friendly Sun Gun. All that space energy free from old Sol. You just need to reallocate it. The Nazi Sun Gun is good fun but there are many other sun guns. <https://en.wikipedia.org/wiki/Sun_gun> ]
[Question] [ Lets say you have a space ship. This ship will do a lot of maneuvers causing a lot of G forces to go in different directions through the ship. During straight acceleration it pushes the people inside to the back of the ship. During rotation around its front/rear axis it pushes people outward, during rotation end over end some are pushed to the sides while others are pushed to the front and back etc. Because it is more interesting for storytelling reasons the ship is not controlled by AI and the more "classical" SF space flight and battles are used with a naval feel to how the ships operate. The question is: How do you design a hallway that allows people and small cargo (1m by 1m max) to always travel through it with the most efficiency? Constraints: * people will move only when forces are lower than 2G's. * at higher G's people and cargo needs to be able to be fastened and not die by falling or getting slammed by everything. So far my idea was to use hexagonal hallways. 2 opposite surfaces have ridges inside that form handholds and ladders when gravity pulls you directly down (or up) the hall. The advantage is that you cant trip as easily across these ridges when it is your "floor". The rest of the surfaces are smooth with long [T shaped slots](https://images-na.ssl-images-amazon.com/images/I/51kLYUFQDPL._SL1000_.jpg) going through them. These slots would allow cargo to slide down the hallway. If gravity changes the weight of the cargo pushes the anchors against its walls preventing it from falling. But this still seems a bit hamstringed. So I am hoping for a more suitable hallway for space ships that people can move through. [Answer] For one thing, hand holds do no good under high G. I can imagine the person flying down the corridor and going splat against a far wall, followed shortly by his fingers. I would have very short sections of hall. The farther you can travel the faster you're going when you hit. Since zigzags would make moving cargo a hideous experience and would really break up usable interior space, let's do what they do in naval ships: bulkhead doors that automatically shut under high G so long as there is no one in the way or better, they are closed by default and only open when under low G and someone/something approaches. These serve two purposes: they shorten the distance someone can "fall" and they minimize air losses from a breach (that can happen even at low Gs). This gives two benefits for the price of one. For additional protection, have the walls (plus floors/ceilings if those are relevant) of the halls contain padded emergency nooks that people can secure themselves in. And pad everything you can. [Answer] Forget ergonomic hallway design. Just use Electro-Magnets All of the interior surfaces within the ship, including all four walls of every hallway are made of magnetically attractable metals. All objects within the ship which are not permanently mounted to a fixed point in the ship, are skinned in a ferrous metal foil. All crew members are required to wear boots, gloves and a spine-guard which contain strong electromagnets. Toe-buttons, hand gesture sensors and (for the spine-guard) a belt mounted on/off switch allow the electromagnets to be activated and deactivated as needed. Free moving objects which are likely to unattended at the moment of unexpected maneuvers have their own electromagnetic anchors so they can be affixed to a wall or desk when not in use. Standard ships protocols requires that all unattended objects be secured when not physically held by a crew member. The sleek and shiny look of futuristic space craft has never been about looks. All those beautiful chrome and battleship gray surfaces are present for safety reasons. [Answer] One single cylindrical corridor that spirals the length of the ship. * When you're accelerating it's a spiral ramp upwards/downwards * When you're rotating then it's "level" (and long) * When you're tumbling end over end down is at least meaningful most of the time (though you may have some issues near the centre of rotation). I will admit that I haven't entirely worked out how to place the doors that come off this corridor. Each room would probably need two doors at right angles to each other off the corridor so at any point one door is across and one is up/down. Secondary advantage: No clear line of fire for boarding parties. [Answer] Have the ship designed as one sphere inside another one. When acceleration was applied to the outer sphere strong electro magnets and induction motors on the inner surfaces would rotate the inner sphere in such a way that the accelerating force was always coming from the same direction for the inner sphere. [Answer] The SF classic "The Mote in God's Eye" describes some of the interiors of Imperial Navy spacecraft. They rotate about the long axis for spin gravity when not under thrust. The ship could be imagined as a skyscraper or office tower when the engine is running, and a rotisserie when not. The ship then basically had fittings to move equipment and dog it down on the appropriate surface when the conditions changed. In larger rooms, things like conference tables were retracted into the "floor" prior to despinning the ship, since the table would have a curvature matching the ship's hull so be unusable under thrust. The table would be flush to the "wall" when the engine is running. Since this is a warship, there is a reasonably large crew (to provide continuous watches, have lots of replacement in case of casualties and man battle damage repair parties), so when the announcement that the ship was de spinning was given, the crew works like a well drilled machine to reorient everything. Hallways would be designed to have two "floor" surfaces, one for spin and one for power, and things like light fixtures, power outlets, switches, maps (you are in Level 5, Section 3) would be placed on the non floor surfaces. For extra mechanical strength, the hallways might be built out of large tubular sections, so there is no "hard" transition between spin and thrust flooring, and everything else is mounted flush, with handholds build along the "walls" to assist in movement during transition periods and when the ship is not spinning and in free fall. Given the design of the spacecraft, there is likely one or more central "elevator" shafts running parallel to the axis of the ship, "hallways" radiating out at each level and one or more circular "hallways" connecting the "spokes". One other feature which will be present in any spaceship, civilian or military, is airlock doors which can seal off sections of the hallway or ship in case of a hull breach. [Answer] Hallways are tiny, and padded. Each hallway is barely big enough for one person to squeeze along, rubbing arms on the walls as she does. These walls are padded. If a maneuver unexpectedly throws her against the wall she will not accelerate far before the wall stops her - she is already against the wall. Really it would seem like the wall suddenly leaned on her and that is how they can describe it. Halls could be one way or you could pass someone going the opposite direction with an over/under maneuver. Robots using the hall always are the "under". People move along the halls no matter what is going on because they are not wusses. If stuff gets hairy you wedge yourself in place with arms and legs and wait a second. Getting pushed and pulled as you keep stride is how you get your space legs. The old hands will laugh at the greenie who gets tumbled backwards until he fetches up against a robot, which inquires politely as to his health. [Answer] So a lot of answers focus specifically on the hallways, and of them, cylindrical passages do make the most sense when considering the orientations that gravity would have on them. They would probably be slightly narrower in radius to prevent out of control bounces following multiple gravity shifts. The hallways would can have moving rails that help move the crew. Specifically, it would probably look similar to an inside-out drop ride: [![enter image description here](https://i.stack.imgur.com/G1F8X.png)](https://i.stack.imgur.com/G1F8X.png) Other than the hallway's shape, I would like to focus on the delivery mechanisms of the hallway itself. The crew members would fasten their suit to the back harness and be transported along the rail. By securing the crew flattened against the surface of the hallway, this has the added benefit of protecting them from flying in the event of a sudden combat maneuver (allowing crew to move between sections of the ship even during combat), as well as the transport not relying on the orientation of the crew members. Also, any moving objects can similarly be transported in such a way. This delivery mechanism also allows multiple crew and objects to be transported at once, without fear of disruptions between crew and objects should a sudden gravity shift occur. Between hallways, or sections of rail, the crew can secure themselves to areas by way of something like a zipline harness, secured to the walls. To keep them protected from any harm while transitioning between rails, each crew suit could be fitted with an advanced 'airbag' system, that can protect the upper (and possibly lower) body in the event that they go for a brief flying session. Hopefully, the harness would keep them from bouncing too far. While inflated, the suit could perhaps look like bubble soccer suits. [![enter image description here](https://i.stack.imgur.com/JT5I2.jpg)](https://i.stack.imgur.com/JT5I2.jpg) The advantages of using such a harness and airbag system with a cylindrical hallway would be: * The ability to transport personnel even in the middle of intense dogfights with enemy warships, disregarding the amount of G's (unless fatal) * Extra protection from broken bones and limbs from sudden impacts and shocks by the airbag system * The harness being multipurpose, allowing the crew to secure themselves in the command bridge, have lunch upside down * Space veterans get to essentially zip-line and roller coaster through the spaceship at high speeds * Multiple rails along the hallways allow for many crew and objects to be transported in parallel, without fear of interference (and concussions from flying objects). [Answer] I think octagon with rope in the center and alternating half walls might work. A perfectly round, cylinder shape might be hard to get a good foothold, but octagon might be better, because flat land to put feet on. The rope would let them climb up against gravity prehaps using a ascender type gadget or slide down, i also thought about fire poles, one going each way. The half walls are would be a metal barrer covering half the passage way than some distance away there is a barrier blocking half the passage way, this will catch falling people and if the barriers are close enough you can climb from metal barrer, however you can avoid it slowing your movement by weaving through the metal barriers. For the metal barriers, picture a double door with one door open. [Answer] I would go with a large suspended sphere in the centre of the ship. this sphere would contain all of the crew and hallways etc, and would always orientate itself so that the bottom of the hallways was where the g force was being applied towards. this would keep everything upright and good. ]
[Question] [ I plan to make this a series of questions to avoid being overly broad. Each question will address a particular fantasy species ("race" in RPG terms). The "racial" traits will be based on the content from this question though the specific race in question will have traits in the question: [Medieval politics with fantasy races](https://worldbuilding.stackexchange.com/questions/28573/medieval-politics-with-fantasy-races) World Concept: Similar to the Percy Jackson or Harry Potter series I am envisioning a world within a world. * Modern day setting * Fantasy races live in secret * An as yet undefined force/magic impairs humans when they interact with magical races/activity My request: I am looking for peoples/cultures/tribes from the real world that no longer exist. The idea here is that x, y, z tribes that based on real world history ceased to functionally exist were actually comprised of a fantasy race passing as human. *For example:* The Huns of this world were actually Dwarves of the magical world. * In the past, fantasy races openly existed alongside humans * Many conflicts we study from the past were actually conflicts between fantasy races * At some point magic divided the human/fantasy worlds * For this question I am specifically interested in Elves. Your answer should provide a historic group or groups that best fit the constraints of the question and provide supporting evidence as to why it is a good answer. Constraints: * The real world tribe (RWT) needs to be from Europe/Asia/Africa * The RWT should have ceased to exist prior to 1500 CE. They can have been destroyed in battle or absorbed into a larger culture or option 3 (whatever that is) * Should meet, as well as possible, the traits defined below (obviously some are magical and aren't possible in humans; I'm looking for compatibility, not exact matches): > > Elves: > > > * Elves are long lived though not immortal. On average elves live to be 350 > * Each elf tends to choose a few skills (usually fewer than 6) to perfect in their lifetime. These can be manufacturing skills, martial > skills, as well as things like trading and public speaking. > * Elves would rather be working on honing their skills (even martial skills) than fighting with others. They are not so much peaceful as > often self absorbed and will ignore provocations > * Once roused to fight they are deadly. They are not naturally stronger or faster but their combat skills are second to none. > * Elves live in multi-racial cities for the most part, though some shun society and live in small enclaves reserved for elves (yes, in > the forest mostly). > * Elves can excel at pretty much anything due to their long lives and penchant for focus on certain things. > * Elves generally tolerate most races, though can often see them as lesser beings due to their short lives > * Elves inherently distrust orcs due to the fact that the orcs can't keep long term agreements > * Elves would probably rule the world if they were not the smallest race by population > * Elves have a higher percentage of their population capable of using magic > > > Additional new traits for the elves: * There are several flavors of elf. Wood, Wild, Dark, Sun, Moon (Yes this is currently D&D based in my head) * They are very similar but do fight one another from time to time. This means an answer should include similar peoples banded into subgroups that are geographically co-located. [Answer] ## Phoenicians There are plenty of good options but I'm going with the [Phoenicians](https://en.wikipedia.org/wiki/Phoenicia). You asked for: > > * Each elf tends to choose a few skills (usually fewer than 6) to perfect in their lifetime. These can be manufacturing skills, martial arts, etc. > > > Humans tend to specialize in a particular skill, so only 6 specialized skills isn't a hard stretch. Specialization is especially easy in a society where you can rely on other people's specialties. Elvish long life and specialization translates to extreme specialization and the formation of specialized guilds in normal humans. The Phoenicians were famous for their metalwork and shipbuilding. It was far enough ahead of surrounding civilizations that metal goods were a major trade good for the Phoenicians. > > * [These can be manufacturing] skills, as well as things like trading and public speaking. > > > One does not have an empire with influence over much of the Mediterranean without the ability to motivate and organize traders, workers and politicians. [![Phoenician Influence](https://i.stack.imgur.com/rqI3W.jpg)](https://i.stack.imgur.com/rqI3W.jpg) ([source](https://en.wikipedia.org/wiki/Phoenicia#/media/File:Griechischen_und_ph%C3%B6nizischen_Kolonien.jpg) Yellow cities are Phoenician) > > * Elves would rather be working on honing their skills (even martial skills) than fighting with others. They are not so much peaceful as often self absorbed and will ignore provocations > > > War is expensive and the Phoenicians are more known for their trade than their war-making (though the Persians were able to build a Phoenician based navy.) > > * Once roused to fight they are deadly. They are not naturally stronger or faster but their combat skills are second to none. > > > Phoenician navies made Persia a great power in the Mediterranean. > > * Elves live in multi-racial cities for the most part, though some shun society and live in small enclaves reserved for elves (yes, in the forest mostly). > > > Any coastal trading city will have a broad exposure to many other cultures. Such exposure helps them make better deals. Religious practices of the Phoenicians had plenty of groves of trees (much to the chagrin of those prudish proto-Israelites) > > * Elves generally tolerate most races, though can often see them as lesser beings due to their short lives. > > > I think normal in-group bias will take care of this one. I think any moderately aggressive culture will have this characteristic. If the Phoenicians didn't do this militarily, they would certainly have done it in trade. > > * Elves have a higher percentage of their population capable of using magic > > > Advance technology is indistinguishable from magic. Also, putting symbols into clay or stone then have an idea pop into the head of a reader is pretty freakin' magical. Their ships certainly appeared magical to anyone who didn't build ships. > > * ...Several flavors of Elves > > > Given the reach of the Phoenician ships, they were in contact with many different regional cultures. A search of "Phoenician Art" shows considerable variation in art styles. While in real life, this indicates that the Phoenicians borrowed art styles from trading partners, in the context of this world, all those different art styles could indicate distinct Elvish 'races'. [Answer] One simple one would be the neanderthals and other extinct branches from the human ancestral tree. Many people now a days have [Neanderthal DNA](https://en.wikipedia.org/wiki/Neanderthal_genetics), but there are no neanderthal still living (that we know of!). We know a little about their culture, but not a lot, meaning that you can make a lot of stuff up to fill in the holes. Even less is known of the [Denisovan](https://en.wikipedia.org/wiki/Denisovan), but evidence shows that their DNA is at least partly responsible for how [well adapted the Inuit are to the cold far north](https://evolution.berkeley.edu/evolibrary/news/170201_extinctrelatives). Now, if ancestors of these groups (and others) had continued to exist, develop, and adapt, then you could extrapolate forward to where descendants of neanderthals are modern day dwarves, and descendants of denisovan are modern day elves, and other ancient side branches developed into trolls, orcs, and whatever else, then you can get a lot of diversity, and say that most people of european and asian descent have at least some dwarf DNA, and most pacific islanders, australian aboriginals, and native american people have at least a little elf DNA, but that those groups didn't actually die out, and there are still more or less pure blood elves and dwarves (maybe with a bit of human DNA thrown in) in out of the way places where no one will bother them. The wiki on [Interbreeding between archaic and modern humans](https://en.wikipedia.org/wiki/Interbreeding_between_archaic_and_modern_humans) has some info on "Neanderthals, Denisovans, as well as several unidentified hominins". The unidentified hominins could be the other races that you are wanting to incorporate. [Answer] Akrotiri - potentially seen as the insipration for Atlantis. It was a bronze age town located on Santorini which profited of the rich soil from the vlocanic eruptions, until such an eruption blew up half of the isalnd and the town along with it (or so the non-magical historians think, little do they know about the truth behind the powerful illusion hiding Atlantis and its elven citizens). > > Each elf tends to choose a few skills (usually fewer than 6) to perfect in their lifetime. These can be manufacturing skills, martial arts, etc. > > > Given the traditional greek system where one would be trained to be phyiscally fit and get a besic education in reading, writing and philosophy or a trade, before specialising in one or any few disciplines. Highly specialised individuals such as artisans, philosophers, but also warriors were not uncommon in the ancient Greek (or as mentioned by @Green Phoenician culture). > > Once roused to fight they are deadly. They are not naturally stronger or faster but their combat skills are second to none. > > > Even though little actual texts survived from the time and we only have excavation, we look at the context. Considering the fact that a small island kept unconquered for 500 years in the face of immense military powers such as Egypt or the Greek states speaks for itself. > > Elves generally tolerate most races, though can often see them as lesser beings due to their short lives. > > > Santorini is a small island which could never have provided enough materials for the risee of such a large city with rich culture without a lot of trade which naturally meant getting in contact with people from different regions and cultures. Thus, it can be assumed that people were quite open to the world. > > Elves generally tolerate most races, though can often see them as lesser beings due to their short lives. > > > Assuming that longevity originally stemmed from better medicines and treatment methods available, it is easy to imagine that the people living within the save quarters of the city lived on average much more safely and longer than people from surrounding smaller island or tribal populations who were sometimes derisively viewed as barbarians 'the ones with beards who do not know how to shave' due to their more primitive lifestyle and shorter, 'dirtier' lives. > > Elves have a higher percentage of their population capable of using magic. > > > As Akrotiri is one of the potential candidates for the mythological Atlantis of Plato's story, which place would be more adequate for suggesting a magic-using society? [Answer] Based on history, we may have a precedent with the Tuatha de Daanan (Children/Tribe of Dana), also known as the Faerie (beautiful people). In mythology, they were long lived magic users, whose influence waned over time and eventually became refugees in their own land, surrounded by the invaders. Historically, the celts were pushed westward and ultimately hit the island of Eire (Ireland), where they pushed out the prior inhabitants. If the legends are any reflection of the reality, then an invading horde of bronze age barbarian refugees contacted a peaceful agrarian society that was at what we might consider a late medieval level of technology and advanced (for the day) practices of personal hygiene (accounting for the reputation for beauty and relatively long life), which they then proceeded to burn, pillage, and destroy. The last known remnants of the Tuatha de Danaan were recorded in legend as dying of old age shortly after the introduction of Christianity to Ireland. The legends of "changelings", where the faerie would leave their infants with a celtic family, are signs of the refugees desperate need to protect their children when all hope was lost for the adults. [Answer] The [Aryans](https://en.wikipedia.org/wiki/Proto-Indo-Europeans) [no offense meant it's an old term with a specific meaning that has since been hijacked by certain unpalatable groups] from the [Eurasian Steppe](https://en.wikipedia.org/wiki/Eurasian_Steppe) came in to Europe in a series of mass migrations, the last of them is thought to have been in the late Bronze Age (c.1000BC). The last large group to follow their ways and culture were known as the [Scythians](https://en.wikipedia.org/wiki/Scythians) I posit that these were the Elves, their cultural longevity was due to their long lives and sophisticated culture. They were however eventually destroyed by the [Sarmatians](https://en.wikipedia.org/wiki/Sarmatians) in the fourth century BC, and for the purposes of this set up, the few remaining pure-bloods scattered into Northern Europe as refugee bands in isolated areas. The Scythians fit the bill reasonably well, they were a highly cultured group who excelled at many crafts, they were friendly with their neighbours, tolerant of other cultures, and they were peerless fighters with the traditional Elven weapon, the bow, from horseback. Importantly they seem to have avoided more battles than they fought, their political influence outside their borders was exercised primarily through money and trade. There is a story that the Persians sent an army into Scythia, to get them to stop supplying the Greeks with grain, the Scythians ran them ragged for months rather than engage them. When the Persians finally got the horsemen to meet them on a battlefield the Scythians' commanders were more interested in hunting a rabbit dinner than watching the overwhelmingly large enemy force deploy. Legend has it that the Persian general was so shaken by the show of total confidence in the face of such superior numbers that he packed up his massive army and went home. The only thing that doesn't really fit your specifications about the Scythians is that the archaeology suggests they were more semi-settled nomads than they were city builders. Otherwise they fit nicely, especially if you cast the Persian empire as the orcs, and there are parallels you could use - vast hordes bent on conquest etc... The reason I used the ancient Aryans as the starting point for this answer is the Drow or Dark Elves; I propose that one could realistically give them a very recent and nasty resurgence within this framework. Drow have certain views on racial superiority, racial purity, and political process that very closely match the views and actions of the Nazi party. In fact staging a [Night of the Long Knives](https://en.wikipedia.org/wiki/Night_of_the_Long_Knives) is their standard way to settle policy disputes at all levels of society. The attempted creation of a master Aryan Race fits too; the fact that they were to be blonde and blue-eyed is obviously either an attempt to breed back to the old Elven stock of generations long past or a transparent attempt to frame the High Elves, who the Drow traditionally despise, for the whole thing. [Answer] How about not going for a whole tribe/people, but for a class/caste of people? The curtain rises on [ancient Rome](https://en.wikipedia.org/wiki/Social_class_in_ancient_Rome), namely the ruling class of the [patricians](https://en.wikipedia.org/wiki/Patrician_(ancient_Rome)). You couldn't become a patrician other than by birth, which suspiciously fits the bill of a possible different race. There were only an overseeable amount of different gentes ([patrician families](https://en.wikipedia.org/wiki/Patrician_(ancient_Rome)#Patrician_families)), some 4-5 dozen namely. This would beautifully fit your longevity and small numbers. Due to segregation by class & status, the patrician elves would often live in elf-only-districts in Rome and a few other cities. These areas being home to lots of beautification and parks with trees and such. The roman pantheon was known to incorporate not only the gods from annexed peoples, but also [elevate emperors into god-hood](https://en.wikipedia.org/wiki/Imperial_cult#Ancient_Rome). Many of your elves can do magic, that would fit perfectly again. [Answer] Two ideas. First, ancient Japan. Specifically, the Samurai, who were in many ways isolated from the rest of the Japanese culture and very fierce warriors. The ancient Japanese culture was very precise about perfecting things in the daily routine; think tea service/ceremony. The weakness here is their isolation from the rest of the world. Second, if it works better for the story for Elves to be more European, you could use Druids. Builders of the monuments such as Stonehenge, they had abilities and knowledge unavailable to others around them. In dealings among other fantasy races, you could cast the Vikings or Arthur's Knights as a foil. It's a shame we're limited to the Eastern hemisphere, or Mayans/Aztecs would make good choices, especially in combination with Eskimos and other early Native Americans and the Polynesian peoples in certain island regions cast for other faerie races. [Answer] How about the [Indus Valley civilization](https://en.wikipedia.org/wiki/Indus_Valley_Civilisation)? They were a bronze age civilization who created huge planned cities, in what is now India and Pakistan. They are one of the few civilizations whose script we haven't yet deciphered. Thus, a good choice to base a mysterious elven race upon. [![Mohenjodaro](https://i.stack.imgur.com/It3Du.jpg)](https://i.stack.imgur.com/It3Du.jpg) (Photograph by M. Imran, on wikipedia) > > Each elf tends to choose a few skills (usually fewer than 6) to > perfect in their lifetime. These can be manufacturing skills, martial > skills, as well as things like trading and public speaking. > > > For a bronze age civilization, they had plenty going for them, so there would have been plenty to learn. Large well planned cities requires planning and architecture skills, sculptures, jewelry, pottery require (different) artistic skills. They traded a lot with other cities, so navigation and ship-building skills were greatly appreciated. Apparently, they also achieved skills in accurate measurement of length, mass, and time, thus requiring mathematicians and engineers. > > Elves would rather be working on honing their skills (even martial skills) > than fighting with others. They are not so much peaceful as often self > absorbed and will ignore provocations > > > While many artifacts have been found in Indus valley cities, not many weapons have been found. Fighting is not that interesting, thus why have weapons? > > Elves live in multi-racial cities for the > most part, though some shun society and live in small enclaves > reserved for elves (yes, in the forest mostly). > > > Indus valley civilization built huge cities complete with drains and public baths. They traded with civilizations as far away as Mesopotamia and Egypt.. so this scenario is completely plausible. > > Elves would probably rule the world if they were not the > smallest race by population > > > Since they are not interested in fighting, why even attempt to rule the world? It is not clear why the Indus valley civilization perished, some scientists believe it was changing climate (increasing aridification). [Answer] The question leaves a lot to be desired, in terms of definition of terms and scope. Except for the longevity and magic part, your description of 'elves' pretty much covers the scope of high-functioning autistics. This group is defined by particular genetic aberrations, but it would certainly not be referred to or categorized into or by the descriptors 'races/hordes/cultures/tribes'. It is sort of like defining all 'red heads' as a 'race'. Are you speaking about a particular sub-set of genetic traits? In which case, these genetic traits could be distributed across many, or all, races. That is, the coincidence of particular genetic traits would not be defined as a race but as a personality sub type. Are you talking about a particular genetic trait that is evident in only ONE race, in which case I posit you are talking about a species? No human race is 'pure' in the sense that it has an abundance of genes only associated with that race, except as caused by localized inbreeding. Most of what we refer to as human 'races' are defined primarily on cosmetics - what the external appearance is. Black, white, brown, etc. Not by intrinsic personality traits or abilities. The later are not a racial characteristic, they are a personality characteristic. Introvert/extrovert, calm/excitable, reserved/gregarious, and so forth. These trait are not limited or defined by 'race'. On the other hand, if you are defining your group as having exclusively particularly different DNA characteristics, such as the number of chromosomes, you are not talking about race, but species. Are your groupings capable of inter-breeding? Can one group share the defining genes that govern the unique characteristics with another group? Can the Orcs somehow acquire the longevity gene, and live to be as old as Elves, or is that gene somehow only capable of being manifest in Elves? On the other, other hand, if you are trying to interlace fantasy world and mythological genetics with real world genetics (similar to Greek mythology allowing limited gene transfer between the Gods and Humans) then looking for past human equivalents is not necessarily the way to go. Render unto mythology what is mythology The answer to this question is only answerable from a mythological perspective. Why not simply posit that all of the Greek, Roman, and other mythological gods were real, truly existed, walked among humans, bred, never really disappeared, but adopted a veil of secrecy to avoid persecution, as the human population reached a critical mass and 'overpowered' their status and power? I mean, seven billion people against one god? That is a lot of persecution. Look what happened to ALL human religions, as the population exploded? Methinks you are far better off looking for antecedents in the mythological gods, not in human genetic divisions. ]
[Question] [ On some computer games it is common to have a setting that disables friendly fire, it does not prevent shooting but it the bullets don't harm friend players. In real life would it be possible to make a weapon (today or near future) that will never shoot someone from your own group? Some sort of facial recognition would help but would need to work in milliseconds to lock the trigger and avoid the shot. But if the person is not directly facing the camera in the weapon or helmet it wouldn't work. Next thought was related to some sort of GPS coordinates or team radio triangulation do determine if a person is from the team or not, but GPS is not that precise and I could only find articles on mobile phone triangulation based on cell towers that a bad precision as well. Third thought was some sort of laser that would reflect from a special material in the teams clothing, it would block the trigger while you are targeting a good person. But depending on the angle the person is the laser would not reflect 180 degrees back to the weapon. [Answer] # Out-there idea: Reverse-frangible bullets: This isn't something invented yet, so it's a bit hypothetical. I imagine a team of armored SWAT or special-forces troops. Right before combat, everyone synchs a set of RFID transponders to the same frequency. Their guns contain bullets that are [frangible](https://en.wikipedia.org/wiki/Frangible_bullet) if they hit an armored target - as long as the tiny internal electromagnet isn't engaged. If the electromagnet is engaged, the projectile is held in an armor-piercing configuration designed to kill armored (or unarmored) opponents. Firing the gun activates the electromagnet, while proximity to the RFID signal of an ally deactivates it. So a bullet set to the RFID signal of your squad deactivates and is frangible against the armor of an ally. At extremely close range, the electromagnet may not be active yet (or alternatively, it may activate and not deactivate in time) so point-blank ranges may be unpredictable. The projectiles would still pack a wallop, but you won't be blowing holes in a co-worker. Against unarmored opponents, I'd guess these bullets would still be lethal, so watch out for hostages and other soft targets. Any bullet that gets *close* to an ally will deactivate, so you don't want to be winging near-miss rounds past friends. Obviously these rounds would take some very sensitive and advanced electronics not yet developed. The margin of error would be very tight. But I never believed they could invent frangible rounds, so why not invent the opposite? Who knows, maybe DARPA is making these things right now... [Answer] Genetically modify your own troops to be immune to the deadly poison with which you coat your weapon's tiny dart rounds. Then when friendly fire accidents occur, the victim will take no more harm than a mosquito bite. Meanwhile, your enemy who are not genetically modified to handle your poison will die as quickly as if they were hit by a high caliber round. [Answer] Going in a little different direction from the rest of the answers, I propose a biochemical weapon. Bullets cause physical damage, and without some really smart, quick acting, and extremely reliable technology, smart bullets would not be viable. Instead, I propose a fast-acting neurotoxin in rounds that can pierce the skin without much damage. The entire team would be treated with an “antidote”/blocker/inhibitor of sorts. ## Advantages * Enemies can’t use stolen technology on the battlefield. The technology would have to be reverse-engineered from scratch * Depending on the situation, the correct neurotoxin can be chosen to induce irritation, paralysis or death ## Limitations * The ammo would have to be handled very careful during production and transportation, since anyone who hasn’t been treated with the antidote would get affected almost immediately. * Biochemical warfare research and production is banned by the UN. [Answer] ## You can’t completely. No matter what approach you take, there is some way to work around it or some dangerous failure path. IFF tagging (mentioned by a number of other answers) can be fooled or hijacked (this has actually been an issue multiple times in the recent past). A smart gun that only fires on identified foes can be hacked (and is still susceptible to the issues of IFF tagging). ‘Just don’t be where the bullets are going’ approaches assume intelligent troops, which is not something you should rely on (there’s a long standing joke about ‘military intelligence’ being an oxymoron, but even ignoring that stereotype mistakes can and will be made), and can just as easily be exploited by intelligent enemies. Biological and chemical weapons have a nasty tendency to be completely indiscriminate and hard to defend against and there will generally be no way to perfectly protect your own troops (there is a reason that most of the smart militaries treated them as an absolute last resort even before they were banned by international treaty). Even if you go really out-there sci-fi/fantasy and have omething that scans brain wave patterns, or looks at the target’s soul, or some other crazy evaluation of intrinsic properties of the target, there will probably be some way to spoof it (or some dangerous failure mode). ## But even if you could, smart soldiers would not want to use it. The issue here is that you’re introducing a couple of new ways for the weapon ti fail, no matter what weapon you are attaching this technology to, and intelligent soldiers do not like weapons that may fail to work. More specifically: * It might misidentify a friendly target as a hostile. * It might misidentify a hostile target as friendly. * It might just stop working completely and brick the weapon. The first case is somewhat scary to any soldier who relies on this system, but the second and third cases are positively terrifying to any sane soldier. A weapon that may not work at when you need it to is, in most cases worse than no weapon at all, especially if the chance of failure is relatively low. This is because most people will, in the heat of the moment, assume the weapon will work, and thus usually put themselves in a dangerous situation when it does not work. [Answer] Implant microchips in allied soldiers. Then, use [smart guns](https://en.wikipedia.org/wiki/Smart_gun) with the same chip, and install integral microprocessors in them that use coordinate-based data to determine how far away the microchips in other allies are. At that point, the distance can be processed along with the average accuracy/dispersion of the gun (perhaps multiplied by some factor in order to provide a safety margin), and a signal can be sent to automatically lock the trigger and/or firing mechanism if the gun is pointed within a certain number of degrees of a friendly. It would depend on range; at point-blank, a person might take up, say, 90 degrees relative to the gun barrel, whereas they might take up 1 or 2 degrees farther away. Note that there's no way to actually determine whether there's, say, a hill or a wall in the way of the friendly. This can result in situations where there's an enemy in front of you followed by three meters of concrete followed by a friendly - and the gun still won't let you shoot. Also, the more components you put in something, the greater risk of failure there is. Also, microchipping your soldiers might not go over well. I still believe that it's better than most other solutions, though, because it allows you to fire essentially all of the time. The rate of "there's an enemy in front of a friendly, but the friendly would be safe if I missed, BUT IT STILL WON'T LET ME SHOOT GAH" would probably be lower than misfire rates. [Answer] It is possible. You make a firearm that has the safety switch [fuzed](https://www.schlockmercenary.com/2001-03-16) in the "safe" state. The real challenge is to make a firearm that meets your "safe" criteria and still does the job well enough to be carried by your soldiers. Fundamentally, the "never" in "never shoot someone from your own group" is a damnably daunting threshold. The reality of warfare is that if such a threshold can be achieved by machines, it typically isn't a place where warfare is undertaken. That's called "civilian life." Soldiers typically bring weapons into areas where life is not so simple. In the situation you describe, one would not sent valuable soldiers. Instead, you might send in a battalion of well armed Roombas to sort things out. Practically speaking, the question would need to be re-asked in a very different structure. First, the premise needs to be questioned: why are we making a gun that can't fire on friends? Perhaps that sounds dumb and simple, but your actual goals may be better achieved by other means -- such as not engaging in warfare in the first place. Diplomats have rarely been implicated in the shootings of colleagues. The second step would be to discuss acceptable failure rates. Something that is permitted to fail one-in-a-million gets designed decidedly different than something that is permitted to fail one-in-a-billion. The third thing is to consider the enemy. Know thy enemy. If you are approaching combat as the ultra-technical eliete, opposing a bunch of farmers who know nothing about advanced weapons, you can solve some of the IFF issues in some ways. However, when fighting against a peer, they can take that IFF and use it to create guns [that only fire upon their enemies](https://www.youtube.com/watch?v=LyhR1THflUU). With those in mind, you could start to craft ways to restrict friendly fire. You didn't specify a technology level, but with present day technology the best solution we have come up with is to train the solder well, so that they point the firearm in the right direction, and only pull the trigger at the right time. [Answer] Frame challenge: A weapon that can't work both ways is a bad weapon. It moves the responsibility both for shooting and for not shooting from the user to some hypotetical technology. The technology can be hacked and no one will be responsible for its major failures (so it WILL be hacked). Well, a soldier can be hacked, too, but at least soldiers can be held responsible for their actions. [Answer] # Step #1: Identify the Allies Some basic [IFF](https://en.wikipedia.org/wiki/Identification_friend_or_foe), it can be several encrypted radio emitters in the uniform of the infantry, or a real-time maintained registry of everything in the battlefield, updated by sensors in all the allied equipment, etc. # Step #2: Make a fired bullet don't harm This is the hardest of all steps, because depending of what are you shooting it cannot be a way to avoid damage to a allied with a fired projectile. This projectile can be any particle or light, etc. IF you are using missiles you probably can the sames with smart bullets, but railguns, laser, neutrino beams, and many other there is no realistic way to avoid damage in a allied with a already fired bullet. [Answer] Trebuchets will shoot at targets with a very long range and the ammo comes from a high point. As long as your troops are smart enough to not be in the destruction path, tbey should be safe. Arrows, too, should be safe with proper shooting discipline. Space your bowmen in lines with a safe distance from each other and have them fire volleys at 45 degrees or so upwards. Most european powers had mastered this by the middle ages. Again, this depends on your own people not being in the middle of an enemy army, so this is situational. I wouldn't have the slightest feeling of pity towards Leroy Jenkins, though. [Answer] ## Your weapon is already in the enemy, you just need to activate it Before the battle begins, the environment is filled with a swarm of nanobots containing botulinum toxin, sarin or some other highly deadly, fast acting toxin. Your people are already infected with a second kind of nanobot that transmits short range IFF codes to make your men immune to their effects, but everyone else is quickly contaminated as the nanobots are designed to tunnel through armor, ventilators, and concreate seeking out people to infect. While most toxins take a minimum of 1-5 minutes to kill, nanobots can kill much faster by carrying the toxins to the exact parts of your body in advance they need to get to making incapacitation and death just as instant as getting shot. At this point you could just send out a giant radio signal commanding them to kill everyone, but such a weapon system could risk to many civilian lives, so when you can't just blanket kill everyone in an area, you follow up by sending in ground troops or drones with "guns" that are basically just remote controls used to confirm targets and activate the bots in your victims. This may still result in the occasional civilian casualties, but you can shoot your fellow soldiers all day long, and it won't matter because its just a low powered, directional radio signal. The reason this works better than the smart bullet solutions is that the nanobots do not kill quickly upon exposure; so, your IFF does not need to make a split second choice under unfavorable conditions. But, it is also better than other toxin based answers because the time between a trigger being pulled and someone dyeing would be almost instant as opposed to several minutes. [Answer] What you are asking for is a smart safety. As long as the system detects a friendly you can't operate the trigger. The biggest issue I see in the system is how the signal or waves or the from of friendly identification is traveling from the soldier to the system. Because the friendly is sending the signal all the time in all directions. Meaning that the system won't be able to distinguish between a friendly soldier behind you, beside you, or in front of you. Once you start thinking about a system is not as simple as: signal on>safety on. Signal off >safety off. Then that thing is not mountable to a rifle. I'm not scientists and I'm sure there are clever solutions. However the biggest issue is the parameters set and reality. Solving the problem only requires throwing more money and attaching a complicated back bag sized computer system. For example imagine [this](https://www.youtube.com/watch?v=iPrIN0Gie-U) "smart scope" but unlike it where it only needs to worry about calculations that relate to a trajectory of a bullet. It has to figure out if a friend or foe is in front of it. This creates another complication and a point of failure. Whatever system or thing your soldiers use identify them as friends. Lastly. This practically offers 0 advantages while potentially causing massive problems. [Answer] It would absolutely be cool to have a thing like that. The problem is that how to do that. You know how in mini games they have that aiming cursor that moves when you turn. If there were glasses that simulate the world as a game, and it was linked to the gun and the brain, the gun might as well just use signals from the brain to signal when to shoot or not. [Answer] The friendly would need to emit a "friendly" signal. Whether that's RFID, RF, motion capture balls, green-screen, or something else is up to you. The gun needs to always be scanning for this signal and needs to have an internal "clutch" which engages and retracts accordingly. Soldiers are typically quite strong so if you try to implement a mechanism which locks their trigger then they will eventually break it. The trigger should always move freely and the internal clutch should be the one providing the pew-pew or no pew-pew. --- All in all this is some great tunnel-visioned utopia but you'll curse the technology once a friendly decides to carry an non anti friendly-fire weapon and decides that you are the one that gets the pleasure of staring down the barrel. [Answer] Easy, make so the weapon has some kind of infra-red laser that detects if it's an ally who's on the aim of the gun, if it's an ally it blocks the "fire" function. ]
[Question] [ Since a lot of people are already asking about multiple-headed creatures, I wonder what about multiple tails? Such as kyuubi, nekomata, etc. (I know some have asked about these mythical creatures, but so far I don't see anyone bringing the topic about multiple tails). What are the benefit and cons for a creature with multiple tails (at least more than two tails)? In biology's point of view, especially to mammalian and reptile types? Will it at least help the animal keep balance or will it make it worse? And how many tails can a creature have based on their body size? [Answer] One potential use could be to create a flexible, spread-out surface for flying or swimming. Birds and aquatic animals have wide, flat tails for this purpose, but these flat tails are generally inflexible, capable of only a single point of articulation. Multiple tails with skin stretched between them would be more flexible and add an extra degree of maneuverability. As an analogous example, bats are more agile than birds because their wings consist of multiple fingers, adding extra points that the wing can bend and fold. Birds never evolved this because their wing evolved from an arm, not a hand. It is very rare for evolution to add a new limb even when it would be beneficial, especially for something as precisely built as a wing. Multiple tails could also be spread out like a peacock's tail to attract mates, but this is unlikely to be beneficial enough to appear on its own. Multiple tails would not provide much extra control for a non-flying animal. Animals that use their tails for control while jumping use them as counterweights; there is no extra benefit for using multiple counterweights as opposed to simply increasing the weight of the single tail. If you want a non-flier, non-swimmer to have multiple tails, perhaps it evolved from a flying or swimming species and re-adapted for land, keeping the multiple tails for attracting mates. [Answer] Some birds have their tail feathers set in such a way that they seem to have double tails. Swallow-tailed kite: ![enter image description here](https://i.stack.imgur.com/8DbZm.jpg) Barn swallow: ![enter image description here](https://i.stack.imgur.com/no1dG.jpg) Long-trained Nightjar: ![enter image description here](https://i.stack.imgur.com/XpUzU.jpg) ![enter image description here](https://i.stack.imgur.com/PMdY1.jpg) Evolution tends to weed out traits that are deleterious, so these tails either help them thrive or in the very least don't interfere with survival. At least in the nightjar's case they could make the bird easier to catch, so there must be a benefit in it to balance things out. A true double-tailed bird could evolve so as to have very fine control on each tail, making them more agile in flight. [Answer] In my opinion, there isn't much benefit from having more than 1 tail. The issue is that almost all animal tails extend off the base of the spine. This essentially gives some animals an additional 5th limb, which they can use to grab onto thing (Monkeys) or balance themselves (Kangaroos or Cheetahs). Having more tails extend out of this base wouldn't help because: 1. Attachment Point: The tails come out of the same base area, all force produced by the tails are applied through this single point and the sum of each tails movements would cancel/add to eachother to produce a single force (aka not going to help balance better). 2. Flexibility: The tails will likely share the same muscle groups, especilly at the base of the tail, similar to our Ring and Pinkie finger. This means that the movement of a single tail will affect the movement of the others. 3. Reach: A tail and arm combined allow for a very long range of reach, by having the tail grab onto something then stretching out with your arms. Having multiple tails however doesn't increase the Reach as the tails are all attached to a single point. 4. Strength: The tails all share a single attachment point and all the muscles used to control the tails will need to be attached to this point. So as the strength of each tail increases, the thickness of this area will also need to increase. 5. Flexibility: Tails are not precision tools like your fingers/hands. Usually the muscles are concentrated into the base of the tail and movements are limited to curling up and swishing back and forth. So you might be able to hold onto a sword, but your not going to be using it to sip wine from a cup like a third arm. In terms of thickness and strength, this will all depend on the purpose of the tail. You can see that Crocodiles and Kangaroos have incredibly thick tails which they can use to lift themselves out of the water or stand on (temporarily). Likewise, animals like the Cheetah have much more uniform and thinner tails which they can move around quickly to help balance themselves out. [Answer] Quoting from my answer here: <https://worldbuilding.stackexchange.com/a/87462/21117> > > A tail is an extension of the spine. That means the tail bones do > have part of the spinal column passing through them. If the fox's > tails are actual tails, then the spine nona-furcates(?) at the base of > the tails, leading to effectively nine independent limbs with > associated motor and sensory functions. It also means a significantly > larger processing facility and muscular structure needed to control > them, which ties in with the Kitsune legend of needing a hundred years > to grow each tail. A newborn with nine tails would be at a severe > disadvantage due to the resources needed to develop eight additional > limbs plus learning to coordinate 13 limbs at a time. > > > If they aren't tails, they're hairy outgrowths, like, as people above > have pointed out, peacock feathers, of limited movement and only > really secondary sexual characteristics. A muscle at the base pulls > them up and out of the way when needed but that's it. That means that > while not very mobile, they're not very heavy either, and since they > grow in at about 2 cm/month, the fox will have plenty of time to > adjust, much like horses do. > > > So, what does that mean for our fox? Firstly, in both cases the tails > would develop after adulthood. In the first case, the fox would have > to develop the brain power to manage nine tails, at which point it > would be smart enough to not need to hunt, i.e., probably smarter than > most humans. Alternately, it won't and much like other mutants will > die painfully. In the second case, the fox has one true tail and > eight, for want of a better word, quills. These will have to be far > shorter than the true tail and will only really be used in mating > displays or as intimidation. At other times, they will be tucked > safely out of the way. > > > [Answer] From a biological standpoint, there isn't much benefit to extra tails other than symmetry, redundancy, or as a display. Otherwise, we'd probably have seen at least one mammal evolve an extra tail by now (after all, we've seen plenty of mammals, including ourselves, lose their tails). Because the tail is an extension of the spine, it's a little difficult to evolve multiple tails, as it needs certain kinds of joints we haven't really seen in the animal kingdom. Since the spine sits on the line of body symmetry it's easier for it to extend through natural selection than to split. The tail connects at the body not in a ball joint, but in a vertebral joint. It is conceivable that you would need some kind of exotic ball joint to support multiple tails, or some kind of "multi-vertebral" structure. Both vertebral and ball joints are only between two bones, however, and there are very few examples of multi-bone "locus" joints in the animal kingdom, much less movable forms of these. It is perhaps important to note, however, that a nekomata has a "forked tail," in that it connects to the body at a single point like a "Y" shape. It is a bit strange that nearly every nekomata depicted in anime and manga doesn't have the forked tail, but two independent tails. The forked form would probably be more likely to evolve than say something like a nine-tailed fox, where all of the tails connect at one point together. From a mythological standpoint, the extra tails are a sign of the creature's power. A nine-tailed fox starts with one tail, then gains an additional tail for every 100 years it lives until it has nine, then begins losing tails for each of the next 100 years. When the fox no longer has any tails, it becomes a god. For nekomata, the legend is that when a cat is 100 years old, it will transform into a nekomata and its tail will fork. To prevent this, sometimes Japanese cat owners would remove their tails if they began to live a long time. This robbed the cat of its power and thus its ability to become a nekomata. In both the legend of the nekomata and the many-tailed-fox, and in the folklore surrounding them, their magical prowess and power is stored in these extra tails. [Answer] Dogs use their tails for communication. Having more tails would make their communication several times more expressive, and evolution could favour that trait in a social animal. Furthermore, artificial selection could also favour it in a pet. You can see how cute and expressive is a three-tailed dog: [![enter image description here](https://i.stack.imgur.com/AzPlB.png)](https://i.stack.imgur.com/AzPlB.png) ([Credits](https://www.dreamstime.com/royalty-free-stock-photo-happy-dog-tail-wagging-image28288925)) Multiple tails can be advantageous for other animals which communicate by them. For example, a double tailed peacock would be impressive. In fact, that's not very different from what has already happened with flowers under artificial selection: roses and other species got multiple layers of petals where their wild ancestors just have one. [Answer] I know of at least two series where the number of tails is proportional to their power. Naruto for example, as he gains more of the kyuubi's tails becomes stronger. There is also the manga Hyper Police and the demon fox Sakura, who is short of the full nine tails and is taken as a sign that her powers have not fully developed. The disadvantages can be the same, by having more or less tails can have particular meaning to the creature/species. If the species normally has one tail, what would not having that tail mean, either naturally or due to an accident? Having more tails could also show other traits. [Answer] One benefit of multiple tails might be fat storage. Many marsupials, lizards (e.g., leopard geckos), some other reptiles, and a couple of rodents are known to store fat in their tails for lean periods (this is known as having an incrassate tail). The amount of fat that can be stored is obviously limited by the dimensions of the tail itself. If the animal had multiple tails, it would be able to store much more fat and thus much more energy than a single-tailed animal would. [![enter image description here](https://i.stack.imgur.com/6YkGy.jpg)](https://i.stack.imgur.com/6YkGy.jpg) Lestodelphys halli, with incrassate tail ]
[Question] [ There is an ancient, satanical practice that is performed in this society called the sabbatical. This ritual takes the form of a festival, in which witches get together and discuss recent events, spells, and other business. It concludes with a ritual that summons a number of demons from hell to take part of the festivities and fornication with the witches. The result of this night of passion is a cambion. A cambion is a demon/human hybrid with magical abilities. They can be male or female and make up the population of witches and warlocks in this society. Because of their demon blood, they are unable to reproduce with normal humans. However, they are also unable to reproduce with each other, effectively making then sterile. This forces them to have to repeat this ritual every generation to increase their numbers. Why would this be the case? [Answer] They have spirits, not souls. Let's go for a ride down a rabbit hole of European Christian fanon you probably didn't know existed. Demons aren't biological This one's just good theology from any perspective. Hell isn't a physical place that sits adjacent to the Earth's mantle. Hell is a state of being, and its native denizens are demons. Demons are angels by creation. Angels and demons are both eternal creatures, like God. They exist outside of time and have free will of their own. As eternal creatures, they saw and understood the Fall and Salvation from the dawn of time. In that timeless moment, they had a choice: "Serviam" or "Non serviam." I will serve, or I will not serve. The "serve" here is literally God, but the proposed hanging point is actually serving man. Because the angels won't participate in Salvation, but God will become incarnate as a man, the angels will ultimately be serving humans. Compared to angels, humans are weak in both will and body, limited in perception and wisdom, and frankly not cut out to tie Michael's sandals. And they're being asked to serve those things. Gross. According to popular interpretations of Revelation 12:4, about a third of the angels were convinced to say no by Satan, and they wage war against the angels. This "war" isn't with blood and swords. That part's just analogy. Instead, they're fighting to bring about what the demons see as the proper natural order. They're fighting over the plan of Salvation, timelessly, as equal beings of equal free will. Spirits don't create Creation in the eternal time posture is an ability that only belongs to God. Spirits, angelic or demonic, have no creative abilities of their own. They can rearrange bits of matter like a smith crafts a sword, but they can't make new things. Humans aren't spiritual beings, though. Humans have souls. Souls aren't eternal, contrary to some sloppy pseudotheological expressions to the contrary. They are created in time, exist in time, express their will in time, through some thoroughly handwaved interplay between God and man. Souls can give rise to new souls. We call this birth. It's entirely natural for souls to do this. Despite being as immaterial as spirits, they're really not related material at all. Demons have an agenda So, back to that war. The most common interpretation of the war is that the demons are fighting to stymie Salvation in general, to prove that they knew better than God all along. In my mind, an equally plausible explanation (and much better one for your story) is that the demons just want proper order. They're angels, after all. They like things to be a certain way, ordered according to cosmic spiritual principles and hierarchies. Mainly, they want humans to assume their proper place as subservient to angels and demons. The Salvation of man is pretty much irrelevant to them. Now, serving a demon instead of God means you're in a state of mortal sin and you're rejecting Salvation and you're going to Hell, but you made friends there, so this might not be the worst thing ever. You're a slave, but better a loyal slave than a rebellious slave when you're spending the latter half of eternity with control freaks. They aren't particularly out to harm their loyal servants. Party with them once a generation? Sure. Pleasure is a good thing, and humans are meant to orient themselves towards the good. Grant them power? You betcha, because humans who orient themselves towards their proper end should have a place in the mortal hierarchy above the ones who don't. Have babies with them? Uhhhh...sure? It's going to get handwavy here. Maybe these cambions/nephilim are seen as an appropriate intermediary between the demons and the humans, because... *Cambions are* their demonic parent, spiritually speaking** They're not animated by a soul, because it takes two souls to do that. They're not drawing their free will from a soul. They get it from a spirit made permanently manifest by hijacking the biology behind human birth. There's no reason to believe this would harm the demon any. Spirits are eternal and indivisible. You don't really get "more" or "less" of a spirit by having it incarnate. This is pretty much a great deal for a demon. Spirits don't fail to do what they intend, limits of physical incarnation aside. They don't have doubt. They're going to be oriented towards the goals of the parent, at least to the limits of their perception of them (and you could play this to any degree - there's no reason for them to be able to access demonic perspective, or not to be able to, or pretty much anywhere in between). They're also natural lieutenants of the demons in the temporal order. The demons would totally do this if the humans agreed to place the cambions/nephilim above themselves in their hierarchy. You can soften it and say they're a mingling of the soul of the human parent and the spirit of the demon, but I say fuck it, go all in. [Answer] > > # Note: as it currently stands, this answer does not meet all the OP's requirements. > > > (The OP's question requires that a cambion be able to produce offspring when mating with a demon. I had missed this requirement when I composed this answer, but it was brought to my attention in comments. I'm waiting to hear back from the OP on a certain point, after which I hope to amend this answer.) > > > They have a mismatched number of chromosomes from their father/mother. This is already the situation with mules: <https://en.wikipedia.org/wiki/Mule#Fertility> > > Mules and hinnies (female mules) have 63 chromosomes, a mixture of the > horse's 64 and the donkey's 62. The different structure and number > usually prevents the chromosomes from pairing up properly and creating > successful embryos, rendering most mules infertile. > > > Humans have 23 pairs of chromosomes, so your cambion inherits 23 chromosomes from its mother. Give the demon a very different number of chromosome pairs...say 66. Now your cambion has 89 chromosomes; many of which have no proper pairing. I don't know if we have any mathematical models for predicting the chances of two cambions successfully reproducing given this situation, but if 1 chromosome difference is enough for mule offspring to be so rare, it seems like only a tiny bit of hand-waving to call it impossible for a cambion with a much larger difference between their paternal and maternal chromosome sets. (Most of the hand-waving would probably be that a cambion would be viable in the first place.) [Answer] Humans are blessed by some sort of god, granting them the ability to generate new life. Demons have the dark ability of creating new life, too, mocking the god's ability. Witches and warlords don't have any creative ability, and since they have demon blood they cannot rely on god's help. Therefore the only option is to mate with a demon and let the demon half do the creative part. [Answer] The half-blood gametes of a Cambion contain a substance that kills both human and Cambion gametes when they combine. Pureblood demons have a recessive gene that allows their gametes to neutralize this toxin. There are rare cases of pureblood demons with mutations in that recessive gene that prevent them from producing offspring with Cambions. [Answer] Male Cambions are sterile. Cambion eggs are incompatible with humans, but compatible with demons. IRL, egg and sperm have a "lock and key" system to prevent cross species fertilization (to an extent, at least). [Answer] ## Demons are an addiction Many people who live with an addiction feel as though they cannot function without it. In some cases, this can be a brutal experience: heroin, for example, strikes directly into the pleasure centers of the brain. In some cases, it can be physically true: theoretically the withdrawal symptoms from extreme alcohol addictions can physically kill you (although medical assistance can help you get through the worst of it). What if demons are the same way? What if, once you've experienced the night of sabbatical, your reproductive organs literally stop functioning meaningfully except with the demons. Your reproductive system becomes addicted to something about them, and are infertile in all other circumstances. Such infertility is well within the realm of biology, and you can fall back on magic if needed to complete the story. Such an addiction could arguably be inherited from mother to child. If your reproductive organs are addicted, and you have a little parasite growing in you which could get in the way of future fixes, your reproductive organs might lash out, crippling the child with the same addictive tendencies before they are even born. As an author, I think you get to choose whether this addiction is something which can be kicked or not. It may be that nobody has had the strength, leaving the potential for a hero of the story to break free, or it may be that the addiction is physically more powerful than the victim, and there are no heroes. [Answer] Magic? You are talking about a creature that exists as a half-daemon as the result of a human reproducing with a daemon. Maybe these Cambions can't harness the same level of energy required to produce a daemon seed. Or perhaps the Cambions are not born of Human Mothers. Maybe the only way a Cambion can be born is by Daemon mothers. I suppose this does not answer the specific question of why can't Cambions reproduce at all? I would be interested in the premise where they can reproduce but their offspring would be human and devoid of the daemon magics. Though this could alter the entire premise of the setting. Maybe the satanic society intentionally sterilizes all of the Cambion babies and it is a huge secret to prevent the Cambions from realizing offspring (to maintain control, or something?). It could be as simple as the half daemon part of them mutates their biology to not resemble a humans. Maybe their reproductive organs don't work or they don't have them 'per se' in the way normal humans have them. Just spit-balling here. If your world is more magical I say lean into the magic. If your world has a strong science aspect where daemon magic can be studied and understood by science then I would say lean into that. ]
[Question] [ If there was a planet half the earth’s diameter, for which every other aspect of the earth was changed proportionally to keep the Earth’s perfect ratio intact (including having the perfect orbital distance from the sun, etc), would animal and plant life, in turn, grow proportionally smaller? Would an Oak tree grow to be 80 feet, or 40? Assume the earth is positioned in just the right place in space with just the right diameter/mass/surface etc to make all this possible. [Answer] Half the planet diameter means 1/8 of the mass (mass goes like volume, thus $(1/2)^3=1/8$, but, since the surface will be twice closer to the center of mass it will also be a 4 times stronger gravity. In total gravity will be half of what we have on Earth. The escape velocity of such a body would be half of what we have on Earth, and based on this never enough praised [chart](https://en.wikipedia.org/wiki/Atmospheric_escape) [![enter image description here](https://i.stack.imgur.com/adFb4.png)](https://i.stack.imgur.com/adFb4.png) we see that the planet would be able to retain oxygen and carbon dioxide, but not water. Sadly, the only life we know is based on water. So, your planet, with the feature you express, could likely not be capable of hosting life as we know it. [Answer] Actually no - there is a good chance that the plant and animal life could even be bigger! We see this effect on isolated islands on Earth - where the smaller landmass can result in [gigantism](https://en.wikipedia.org/wiki/Island_gigantism) in certain species. If you read that and apply it to your question...it's tricky. I would expect some species to grow bigger (eg birds - especially considering lower gravity would make it easier to fly), and some to grow smaller (eg bison/deer/whales because there's just less grazing space for maintaining a sufficiently large breeding population unless they shrink - see [insular dwarfism](https://en.wikipedia.org/wiki/Insular_dwarfism) for some real-world examples). As for "what would happen if you placed a human in this world?" - There is an excellent answer [Human/mammal growth on Mars](https://worldbuilding.stackexchange.com/a/496/28789) on what would happen to a human on Mars, which is just over half the size of Earth. [Answer] This started as a comment on another answer but got too large, apologies if it reads like one. Mars (diameter 6790 kilometers) is only slightly more than half the size of Earth (diameter 12750 kilometers). so for ease of explanation, I'm going to use it as the example despite being BIGGER than the planet in the question. Atmosphere One of Mar's biggest issues as a life-sustaining planet is that its core was too small to stay molten enough to generate a powerful magnetic field, (this was indeed compounded by its extra distance from the sun). Once that magnetic field diminished in strength then the Solar wind was able to rip Mars's atmosphere off making the planet unsuitable for complex life (we aren't ruling out microbes etc yet) so that's a big problem for life evolving at all, let alone smaller, bigger or the same size. Gravity Since Mars is a lot smaller it has less mass than Earth, the surface gravity on Mars is also a lot less than the surface gravity on Earth. The surface gravity on Mars is only about 38% of the surface gravity on Earth, so if you weigh 100 pounds on Earth, you would weigh only 38 pounds on Mars. this then causes the issue of atmospheric density... if you managed to have the core stay molten long enough for complex life to evolve, you'd still have an atmosphere a lot less dense than Earths, meaning any life would need to be able to survive on significantly less air than they do on earth. Sorry to be so negative but the size of life doesn't really come into it when the likelihood of life at all is so very small. if you like Handwavium as the explanation of how life could survive, then I'd recommend mixmastered's answer to the most likely outcome on what that life would be like. [Answer] Not to detract from the other very fine answers, but I suspect that there are variables you could modify. For instance, if the composition of the core were different to the Earth's then you might have a sufficient magnetic field and increased density. This might allow a smaller planet to retain atmosphere and have a similar surface gravity to Earth. For the sake of argument, let's say that the planet is half the size of the Earth but the other factors are broadly similar - the atmosphere, gravity, temperatures, length of day, etc. The question then is whether the reduced space alone would result in evolutionary selection pressure towards smaller creatures. Personally I think that it's unlikely. Smaller populations, maybe. But I don't see any particular impediment to 'normal' (Earth-normal that is) sized creatures being the norm. The balance we have reached seems more to do with the direct factors: gravity, atmosphere, temperature, etc. Indirect factors like room to expand and so on would seem to be more likely to result in smaller populations or reduced diversity than to produce smaller individuals. If you were to find a rock like this, Terraform it, populate it with an Earth-native ecosystem and let it develop independently for a few hundred thousand years and things probably wouldn't change all that much more than on a world more like Earth in size. Maybe a little less, given the reduced opportunity for geographic isolation. [Answer] Nope, the (plant) life would likely be bigger than on Earth. Assuming the density is the same, the mass would be 1/8 that of Earth, and the radius would be 1/2 that of Earth, so the surface gravity would be 1/2 that of Earth (proportional to M/R^2). This would mean that an oak tree would grow to 160 meters instead of 80. However, the atmospheric pressure would be much lower and effect for the partial pressure of oxygen would be more pronounced still (even if offset by the larger plant life). This means that the animal life would be smaller than on Earth, most likely, but definitely not just twice as small. ]
[Question] [ Would it be possible for an alien species to have liquid nitrogen for its blood? What would be required for that to work? What kind of environment would it need to exist in? [Answer] Short answer is no. Longer version goes as follows... Blood exists for a number of reasons in an organism, but the primary one is the distribution of oxygen to all the other cells in the body. Nitrogen isn't inert per se, but the fact that it exists in such large quantities in the Earth's atmosphere but doesn't react with the 22% or so O2 should tell you that it's not going to 'store' oxygen to carry it around the body. The reason why our blood contains a lot of iron (hemoglobin) is because iron reacts very well with oxygen. You've no doubt seen how quickly iron left exposed rusts; well rust is actually just Iron Oxide, or iron that's reacted with oxygen. That reaction allows the blood in a normal body to capture oxygen and then release it where it's needed so that all the cells of our body can get oxygen for their normal chemical processes. If on the other hand what you're really asking is can a being exist that captures an oxidiser in a form that allows it to be in a really cold environment, you might want to look at using fluorine as an oxidising agent; my understanding is that you can work at much lower temperatures using halogens to transport the fluorine in much the same way as hemoglobins transport the oxygen in life on earth. But for the sake of argument The temperature at which oxygen becomes liquid is only about 10 degrees higher than the temperature at which nitrogen becomes liquid. Which means there's another possibility... If you have a VERY cold planet, AND instead of an 'atmosphere' you have a 'sea' of liquid N2 and O2 in similar proportions to that on Earth, AND you have some mechanism to replenish O2 once it is used by an organic creature, that creature may not need to have blood at all. Imagine (if you will) a creature that looks somewhere between a fish and a piece of lace; it swims about in this sea, and instead of gills, it allows the sea itself to pass through all parts of its body, which then extracts the liquid O2 for the metabolic needs of all its cells. It might exist in the form of (say) a hollow tube with propulsion mechanisms inside. The idea is that the tube itself would have many hollow tunnels through it, maximising internal surface area and allowing the organism to breathe. The precedent may be insect life on earth today, which doesn't have lungs but instead absorbs its O2 needs through its carapace via osmosis. This is sufficient for a very small creature and it's the primary limitation on insect growth; if they grow too large, their internal organs literally suffocate. But, our lacy or tubular fish should have access to sufficient amounts of O2 that it can feed its own cells out of the sea. This wouldn't be blood per se, but if the sea ran through many different arterial entry points and through the body before being expelled, it would function while inside those tunnels through the body in a manner similar to blood. It, like insects, would be limited in the size it could grow to but would at least experience liquid nitrogen running through it as an oxidising medium. [Answer] ### Liquid nitrogen could form the (majority of) blood of a creature If the ambient temperature/pressure conditions are right for nitrogen to remain liquid, it would be a reasonable kind of blood substrate, the equivalent of water in human blood. The primary function of blood in a living organism is to transport dissolved molecules around the body, such as hormones and cells in humans. [Several](https://www.researchgate.net/publication/251151450_Solubility_of_1Pentene_Ice_in_Liquid_Nitrogen_and_Argon_at_the_Standard_Boiling_Points_of_the_Solvents) [papers](https://www.researchgate.net/publication/243210986_The_solubility_of_solidified_bromoethane_C_2H_5Br_in_liquid_nitrogen_at_774_K) have investigated the solubility of chemicals in liquid nitrogen, so it is fairly appropriate for this purpose. However, the blood would not be pure liquid nitrogen, no more than human blood is pure water. The carried cells and hormones are what makes it blood, and the dissolved materials would be crucial for the liquid-nitrogen-based blood to be blood. [Answer] Blood serves to transfer heat. Liquid nitrogen is good at this. I have speculated about a super cold creature based on the phenomenon of [superfluidity](https://en.wikipedia.org/wiki/Superfluidity). Superfluids are sort of animal like in that they crawl around, seeming to defy the laws that govern hotter things. A [boojum](https://en.wikipedia.org/wiki/Boojum_(superfluidity)) is a weird pattern that can form on superfluids, a superconducting current giving way to a geometric shape. [![boojums](https://i.stack.imgur.com/BBLyv.jpg)](https://i.stack.imgur.com/BBLyv.jpg) Pair of point defects, called "Boojums," in a thin, hybrid-aligned nematic film. <https://www.nsf.gov/news/mmg/mmg_disp.jsp?med_id=68656&from=mmg> It is spooky and otherworldly. A creature based on these phenomena would be good stuff for concept-drives SF. And the liquid nitrogen - it would be for heat transfer. That is what we use liquid nitrogen for and it is also an important role of our blood - moving heat from hot places to places where it can be shed in sweat and breath. So too your Boojum - its liquid nitrogen blood would move heat off to the radiant organs to be emitted, keeping its superconducting body chilly. [Answer] First, define "blood". There are lots of terrestrial organisms which we might colloquial refer to as having "blood", but which technically speaking do not. E.g., arthropods have hemolymph, a fluid "equivalent to blood", but which is not actually blood. In insects, it doesn't even need to carry oxygen, because the animals tissues are directly oxygenated by tracheal tubes. So, what functions do you want a solution based on LN2 solute to perform in order to be comfortable with calling it "blood"? That will determine whether or not having liquid nitrogen is possible! One of the characteristics of blood is that is an extracellular fluid. I.e., LN2 need not necessarily perform as the primary biosolvent, analogous to water, in an organism in order to have other properties which would allow us to call it "blood". Perhaps, for example, you could have an organism that uses oxygen diflouride as its intracellular biosolvent (like the aliens from Robert Forward's Camelot 30K), despite existing in a larger LN2 environment. Such a creature might have cell membranes that are monolayered, to interface between the polar internal solvent and the non-polar external environment, or even non-existent, with cells being bounded solely by the interface between a bubble of OF2 and the surrounding N2 (although it would be difficult to develop multicellularity in that case, which would kind of preclude the development of "blood" entirely--so we'll assume that the creature does have proper cell membranes of some sort, at least!) Given the relative scarcity of fluorine, this might make a lot of sense for an organism that needs to manufacture its own internal biosolvent, and thus needs to use it as sparingly as possible, while taking advantage of some other more abundant fluid in its environment for other purposes. Such a creature could "inhale" and "exhale" LN2 for heat regulation or propulsion, but it seems to me that one of the critical defining characteristics of "blood" should be that it is contained inside the organism, and separated from the environment. So, what could such a creature using internally-circulating LN2 for. so as not to waste its primary biosolvent? Well, there's heat regulation, and while LN2 isn't a fantastic solvent, it can dissolve some things, so it could transport simple hormones & metabolites (like dissolved methane or hydrogen)... and really, blood doesn't need to be a good solvent, even to do all the same stuff our blood does, because it can carry non-dissolved, suspended solid particles (e.g., blood cells). So, an LN2 circulatory system could serve as a critical means of transporting immune cells, metabolite transport vesicles, and all sorts of other suspended stuff around a cryogenic creature's body. Lots of answers focus on the problems of transporting oxygen in LN2-based "blood", but I think that's a red herring. For one thing, the ability of our blood to transport O2 is not dependent on its solubility in water; we use specialized proteins in solid, suspended oxygen-transport cells for that purpose, and so could a cryogenic creature. Furthermore, I don't think oxygen, or even oxidizer, transport needs to be a criterion for calling something "blood", at least in a colloquial sense, anyway. Maybe the creature breathes hydrogen, instead, which may or may not be primarily transported by it's blood. So, yeah, if we accept that it is plausible for life to exist at the relevant temperatures at all, I'd say liquid nitrogen blood is entirely possible. And if we accept that much, it's not that much of a further stretch to accept LN2 actually acting as a primary biosolvent after all. LN2 isn't a fantastic solvent, largely because it's just so freakin' cold, but there's actually a surprising amount of stuff that does dissolve in it, including several classes of organic compounds and silanols. Silanols (the silicon-based equivalent of organic alcohols) are highly reactive at our temperatures, but would be far more stable and useful for building metabolic processes out of at LN2 temperatures. It may therefore not be exceptionally likely, but certainly plausible enough for the purposes of a hard science fiction story, for there to exist cryogenic life using a mixture of organic and silicon-based chemistry in an LN2 solvent--and thus naturally having LN2-based "blood" as well. [Answer] Nitrogen is liquid at very low temperatures for pressures around 100 kPa, and is not so reactive with other gases to be useful in the same way blood is. You might object that also water alone is not a so good at carrying gases (no living creature uses pure water as blood), but blood is a water based solution, therefore there could be a liquid nitogen based solution suitable for carrying gases. True, but at those low temperatures solubility and reactivity of other substances into nitrogen is going to be very low, therefore you cannot simply rely on physical or chemical transport. And, again, at those temperatures also other oxyding gases (oxygen, fluorine, chlorine, etc.) are liquid, so it would be hard to have some breathing as we know it, without even mentioning the hardship of having life suited chemical reactions in those conditions. [Answer] This is pretty tricky and I miss few points in the answers provided by others. First lets understand the purpose of blood itself. It exists mainly to transport oxygen and other substances needed for keeping the chemical processes in the organism. Oxygen is necessary for burning - to produce the energy. Other materials are used either as a fuel for burning (sugar), as a building particles of the body (proteins, to some level also fat) or to be used to control the chemical balance of the organism (pretty much everything else). Of course the role assignment is somewhat simplified. As pointed out in other answers, blood also transports heat. Now before we move on, one should argue what should we actually call life. In a traditional approach it is a form based on carbon, that uses oxygen to produce energy etc. But a more general approach is that it can be any form that is self sustainable, capable of reproduction, consuming whatever nutrition it needs and producing various kinds of metabolism products. Again it is a vast simplification and Wikipedia has a [good article](https://en.wikipedia.org/wiki/Life) to start with this discussion. The carbon based protein cannot serve their role in life in the temperature necessary to keep the nitrogen liquid. They need a water based solvent and water freezes below 0 Centigrade. Some organisms manage to keep their temperature higher than that but still it is nowhere close to the temperature where nitrogen is no longer a gas. Now let's drop the carbon part of life as we know it on Earth and think of some very cold environment (already suggested by others in their answers and comments - like Triton). Your life form will have to be build of something totally different, like silicone, metals, maybe some naturally created alloys and other chemicals that are fluid in the range of temperatures where the nitrogen remains fluid. If those minerals can be solved in nitrogen then your creature could use it as main body solvent and consequently as a base for your blood. I am no expert in this area but the basic [Google search results](https://www.researchgate.net/post/Can_we_use_liquid_nitrogen_as_a_solvent_for_the_extraction_of_phytochemicals_from_plant_material) show there are minerals for which liquid nitrogen can be a solvent. So imagine a creature that in terms of its building particles resembles more our electronic devices, with silicone based "neural" cells for example and you might end up with a creature whose blood is mostly liquid nitrogen. Note - I lack knowledge to imagine other necessary particles to make such life form, but you have a point to start. [Answer] One thing to consider is that it would be quite difficult for life to evolve in temperatures around the temperature of liquid nitrogen. Evolution and biology need chemical reactions, and those are rather few and far between at -196 C. I am not saying it's impossible, but your aliens would be very special indeed ;) [Answer] # Unlikely; consider a nitrogen atmosphere with ammonia oceans/blood instead First, large reservoirs of molecular nitrogen (N2) are rarely found in the universe. Instead, nitrogen is more commonly found in ammonia (NH3). We happen to have N2 in Earth's atmosphere because it was a byproduct of early life; it came from the NH3 in the primordial atmosphere. We have yet to find another planet with naturally occurring N2. Using N2 as a biological solvent thus creates a chicken-and-egg problem. How does life which uses N2 arise from a planet which does not naturally have N2? Second, the boiling point of N2 is -196°C = 77 K. At those temperatures, chemical reactions will occur so slowly that life will arise and evolve at an incredibly slow rate. Finally, at the temperature and pressure needed for liquid N2, there would be few materials left in a gaseous phase to comprise the atmosphere of your planet. You need at least some atmosphere to create pressure to keep the N2 from boiling! And don't expect N2 to stably co-exist as both a liquid and a gas -- the rotation of a planet is one of many causes that would shift the temperature and pressure off of a phase boundary! Instead, consider ammonia (NH3) itself as the solvent for life. Advantages include: 1. It is the most common form of nitrogen in the universe, and ubiquitous among known planets. 2. Liquid form between -78°C and -33°C. This would be a planet much colder than Earth, but still common enough in the universe and warm enough to permit a decent rate of chemical reactions. 3. Like water, it is polar and dissolves nearly the same materials. Alkali metals such as sodium and potassium easily ionize -- producing blue solutions and thus a blue planet -- as well as other electropositive metals such as calcium and magnesium. Salts ionize easily in ammonia. Many organic compounds undergo acidic or alkali reactions when dissolved in ammonia, forming polar compounds and thus becoming soluble. 4. Has its own acid-base chemistry. Just as water dissociates into hydronium (H3O+) and hydroxyl (OH-) ions, ammonia dissociates into ammonium (NH4+) and amide (NH2-) ions, with a dissociation constant of about $K = 10^{-30}$. 5. Water dissolves easily in ammonia, as both are polar molecules, forming a solution that is more acidic than neutral ammonia. Indeed, water could a poisonous waste product of life, just as ammonia is to our life! 6. Like water, dissolved substances diffuse readily. This another important property that contributes to life, as living things often do not need to actively transport molecules to bring them together for chemical reactions. Diffusion happens more rapidly in ammonia that water due to the lower viscosity. 7. Also like water, nonpolar molecules don't mix with ammonia. Lipids (oils, fats, and waxes) form into membrane sheets, which can further wrap into 3-dimensional compartments (organelles and cells) with solutions of ammonia on the inside and outside. The membrane keeps the inside substances inside, and the outside substances outside, preventing diffusion. Because living things need structure, they need to keep things where they belong, and membranes provide this separation. 8. Ammonia is a good material to transport and dissipate heat. It has a decent heat capacity and heat of vaporization. Many organisms could circulate sap or blood made primarliy of ammonia, to help the organism avoid overheating. Some organisms could also evaporate ammonia for "sweating". 9. As shown in the Miller-Urey experiment, it is part of an abiotic mixture of compounds that can form simple organic molecules like lipids, sugars, and amino acids. 10. Nitrogen gas N2 could evolve as the equivalent of our O2. It would be a waste product of early photosynthetic bacteria, become abundant in the atmosphere, and then become the respiratory gas for most living things. It is very soluble in ammonia ([0.1124 vol/vol](https://pubchem.ncbi.nlm.nih.gov/compound/nitrogen#section=Solubility)) -- no need for a hemoglobin-like carrier! [Answer] You can't use ONLY liquid nitrogen. Blood is supposed to transfer O2 to various parts of the body, keep your warm, etc. It could be the plasma (the liquid in which the cells go around in), and have many other cells in it. But, those cells would have to be adapted to surviving in an EXTREMELY cold environment (eg: Uranus, Pluto). [Answer] Would it be possible for an alien species to have liquid nitrogen for its blood? Since I am not familiar with all the biological processes of this alien I am unable to determine whether or not liquid nitrogen would be a viable blood analog. That said, it seems reasonable enough to me and verisimilitude is always context dependent. What would be required for [liquid nitrogen as a blood analog] to work? Most answers have referenced a low temperature as being a necessity for liquid nitrogen; however, it is theoretically possible for nitrogen to be in the liquid phase at normal ambient earth temperature given enough pressure. From what I can tell, this hasn't been done for practical reasons but it may be within the realm of possibility. The pressures required are likely a few orders of magnitude higher than earth atmosphere. Related discussion may be found here <https://physics.stackexchange.com/questions/29523/pressure-of-sealed-in-liquid-nitrogen> What kind of environment would [the alien] need to exist in? In order for internal pressures of this magnitude to exist in this alien, I can think of two possible scenarios. 1. The alien has an incredibly robust vascular system to resist the strain caused by the difference between the internal and external pressure 2. The alien lives in an extremely high-pressure environment to counteract the internal pressure. This opens up the possibility of an alien with a highly developed internal hydraulic system. Perhaps it would be similar to what can be seen in jumping spiders. They are able to jump great distances without the necessity of highly developed muscles which other creatures such as a grasshopper rely on. <https://en.wikipedia.org/wiki/Jumping_spider#Behavior> ]
[Question] [ ## Situation: The vertebrate life of a distant planet uses biogenic silica for structural support. However, biogenic silica is soluble in water, but ([according to this article](https://www.sciencedirect.com/science/article/pii/B008043751607095X)) its solubility decreases by having aluminum within its matrix. Thus, the idea is to have aluminum-based blood produced from within the biogenic silica bones. ## Question: What would the attributes of aluminum-based blood be? * Color in oxygenated state * Color in deoxygenated state * Ability to transport oxygen * Ideal environment [Answer] I'm going to go for a slightly unsatisfactory answer here and say that you can make up anything you want and it'll be OK. The problem is that there are no examples of biological processes that use aluminium. From the encyclopedia of metalloproteins, the entry for "[aluminum in biological processes](https://link.springer.com/referenceworkentry/10.1007/978-1-4614-1533-6_105)" says: > > Aluminum is neither required by biological systems nor is it known to participate in any essential biological processes. While today all living organisms contain some aluminum, there is no scientific evidence that any organism uses aluminum for any biological purpose. There is similarly no evidence from the proteome or genome that any organism has utilized aluminum at any time in the evolutionary record. Aluminum’s abundance and paradoxical lack of biological function remains a biochemical enigma. > > > > > It is argued that aluminum’s absence from biochemical processes can be best explained in terms of its “historical” absence from biochemical evolution (Exley 2009a). In spite of its abundance in the Earth’s crust, aluminum was not biologically available for the greater part of biochemical evolution. > > > The linked reference ([Using Darwin in helping to define the biological essentiality of silicon and aluminium](https://www.sciencedaily.com/releases/2009/11/091116173632.htm)) is behind a paywall, but does have some potentially interesting things to say... 1. Aluminium biochemistry is potentially a bit rubbish compared to more commonly used metals > > aluminium’s slow ligand exchange rates are suggested to preclude any efficacy as a metal co-factor for enzymes > > > 2. Aluminium has had historically very low bioavailability > > There is evidence in DNA that non-essential heavy metals such as cadmium have at a previous time in biochemical evolution been both encountered and selected > out of biochemistry... There are no known designed-for-purpose mechanisms by > which aluminium is specifically either kept out of or removed from biota, nor is there evidence in biochemical evolution of significant encounters between biota and biologically available aluminium. Therefore, even allowing for its ubiquity within the Earth’s crust, the logical explanation of the non-essentiality of aluminium must be that biochemical evolution has proceeded in the absence of biologically-reactive forms of the metal > > > This all adds up to say that there are no real-world examples of the chemicals you're interested in, and so no-one can really answer your questions in a useful way. Not only that, but the chances of aluminium-using biota arising naturally are pretty small in the first place. I'd suggest that you stablise your silica parts with aluminium-bearing chemicals from the environment, but give up on the idea of aluminium-based blood. If you weren't prepared to do that, then you could just handwave in any colors and flavors that you like, because no-one is realistically going to be able to prove you wrong. [Answer] Hemoglobin's transport of blood relies on its ability to reversibly bind its iron to oxygen. When hemoglobin releases oxygen, the iron captures water. When aluminum binds to ligands, it forms a strong bond and will not be able to easily release the captured oxygen. This makes it difficult for aluminum compounds to transport oxygen. One alternative is a cell similar to a "respirocyte". Respirocytes are theoretical red blood cell substitutes with 236 times the capacity for oxygen storage. They are essentially nanoscale pressure vessels. A respirocyte would require a durable nanostructure. A nanostructure composed of aluminum nanograins encapsulated by aluminum-nickel metallic glass could allow your organisms to transport oxygen in aluminum cells or organelles. Some ribosome-like machine could synthesize these complex structures. I don't know what color the blood would take on, but I do know that the color will not change between oxygenated and deoxygenated states because the oxygen is captured within a structure and not causing any chemical change. The ability to transport oxygen as I mentioned would be around 200 times greater than a red blood cell. Information from [The Ubiquity of Iron](https://pubs.acs.org/doi/10.1021/cb300323q), [Exploratory design in medical nanotechnology: a mechanical artificial red cell](https://pubmed.ncbi.nlm.nih.gov/9663339/), [Hierarchical nanostructured aluminum alloy with ultrahigh strength and large plasticity](https://www.nature.com/articles/s41467-019-13087-4) [Answer] Frame challenge You don't need anything as exotic as aluminum to stabilize silicate bones. Silica is only weakly soluble in water, and you want it to be possible to redissolve to allow bone remodeling anyway. The solubility of silica is strongly dependent on pH, because SiO2 dissolves by attaching hydroxide groups to form silicic acid, Si(OH)4. Silica bones can thus be stabilized simply by embedding silica crystals in a protein matrix which protects them from attack by hydroxyl ions; or by simply making the blood slightly acidic; or both. [Answer] ## Use enzymes centred on aluminium oxychloride nanoparticles Aluminium is a tricky choice. It only forms soluble compounds at very low or very high pH. At high pH, you will not be able to deoxygenate it; you'll have a load of biologically useless aluminate ions. Low pH is better; there are mixed species aluminium oxychlorides which can swap oxygen or chlorine in depending on pH, chlorine and oxygen concentration. The problem here is, they aren't soluble. The solution: nanoparticles. Have the particles bonded to some organic bits that stabilise/control them, similar to an active metal site in a conventional enzyme (or the active cluster in photosystem II), in a blood teeming with HCl. When oxygen concentration is high, you replace chlorine with oxygen. The organic part of the enzyme does the work of regulating the details. Your blood is white and milky regardless of oxygenation state. The lifeform is alien; we don't have blood with such low pH on earth. Deodorant companies will try to slay your aliens by the billions and pack their blood into sticks / into emulsions on roller balls. FWIW, I did my masters on certain synthetic amorphous aluminosilicates; I recommend keeping the bones separate from the blood question. Calcium phosphate is insoluble and we make bones out of it just fine (Our bodies take soluble calcium and phosphate separately and join them together as needed). If you want to stick Al in as a strengthening impurity, fine,but you won't easily make bones by precipitating aluminosilicates. If you really really want those bones and don't actually care about blood, google aluminosilicate geopolymers. [Answer] I'm not sure that you will like the answer, but aluminium salts are colourless. Aluminium is most commonly found in it's +3 oxidation state although +2 and +1 are known. Aluminium reacts very readily with oxygen forming its trivalent oxide Al2O3 which is very stable and also insoluble. [Answer] Biological aluminum can be reddish purple! However I don't know if this kind of molecule could carry oxygen the way an iron containing protein complex like hemoglobin can. From Biology SE's [Do cochineals ("scale bugs") form aluminum complexes themselves? Where do they get such large quantities so quickly and how do they handle it safely?](https://biology.stackexchange.com/q/108293/27918) [![Figure 2. Salasaca dyer showing red woollen cloths with modified cochineal red colours. Ecuador. Photo: A. Roquero. from Ana Roquero (2008) Textile Society of America Symposium Proceedings "Identification of Red Dyes in Textiles from the Andean Region"](https://i.stack.imgur.com/gCQDvm.jpg)](https://i.stack.imgur.com/gCQDv.jpg) [!["Dactylopius confusus crushed scale insect, Fort Collins, Colorado, United States" from Wikimedia](https://i.stack.imgur.com/KvFwtm.jpg)](https://i.stack.imgur.com/KvFwt.jpg) Click figures for full size. above first: "Figure 2. Salasaca dyer showing red woollen cloths with modified cochineal red colours. Ecuador. Photo: A. Roquero." from Ana Roquero (2008) Textile Society of America Symposium Proceedings [Identification of Red Dyes in Textiles from the Andean Region](https://digitalcommons.unl.edu/cgi/viewcontent.cgi?referer=https://en.wikipedia.org/&httpsredir=1&article=1129&context=tsaconf) above second: "Dactylopius confusus crushed scale insect, Fort Collins, Colorado, United States" from [Wikimedia](https://commons.wikimedia.org/wiki/File:Dactylopius_confusus_crushed.jpg). below first: "scale bugs" on my houseplant, perhaps female Dactylopius confusus or Dactylopius coccus, from <https://biology.stackexchange.com/q/108276/27918> below second: Structure of carmine from [Wikipedia](https://en.wikipedia.org/wiki/File:Carmine.svg) [![is this a scale bug (northern Taiwan nursery plant)](https://i.stack.imgur.com/dm9h2m.jpg)](https://i.stack.imgur.com/dm9h2.jpg) [![Structure of carmine](https://i.stack.imgur.com/ro1RI.png)](https://i.stack.imgur.com/cxbRS.png) [Answer] It depends on the fluid in the blood, if it's more hydrogenous that oxygenated then you can use [This](https://link.springer.com/article/10.1007/s00894-012-1665-z) to circulated oxygen(or any other gas that fits.) It would also (if hydrogenous) likely be similar to [this](https://pubs.acs.org/doi/abs/10.1021/acsearthspacechem.1c00324?source=cen), plus it would result in dark grey oxygenated blood color, and silver colored when deoxygenated. It would be ideal in a very dry environment due to the toxicity in water. In other words, it would have to be in a desert. ]
[Question] [ I'm working on a concept of universe creation. The best way to describe it in a sentence is the Judeo-Christian Creation Story but from God's point of view. My question is, staying as close to hard-physics as possible, what is the minimum amount of universe needed to be created to prevent humans from figuring it out. The mechanism of creation is handwaved at the moment, but the two I'm considering is a Dyson sphere type construction that would be built in the "higher" universe (so a sharing of actual space, but humans would effectively be in a confined area). The other option is a simulation. I'm leaning towards the simulation idea because of quantum mechanics propensity for not being "defined" until observed (like an RNG that doesn't generate data until needed). However, for either option, the following constraints are in place. * 6,000-10,000-year-old universe * must give the impression of a 13 billion-year-old universe I'm less concerned with Earth itself since you can create something that looks old. It's more the celestial side of things that is giving me problems. Like how to make light appear to be coming from outside the limit of the universe. How big does the universe need to be to compensate for actual measurements taken from earth (like how we use the orbit of earth to get the distance of stars). Etc. Voyager 1 is something like 11 billion miles away, so I guess that's the minimum. Certainly, it would be hard to get smaller than the solar system. But in a hard-science environment (at least inside the universe\) how small can I make it so that humanity would not figure it out with modern technology. --- \ What I mean is that inside the universe, physics is exactly like ours as we understand it right now (unless necessary for this concept to work). And so any limitations on the universe would have to be undetectable to modern equipment [Answer] If God created the universe, and it’s 10,000 years old (in God’s inertial reference frame), then it only needs to be 20,000 light years across, centred on the solar system. The light that appears to come from further away could have been created, already in motion, at the same time as the rest of the universe. [Answer] If your Godlike masters have the power of holography, there is no lower bound beyond the size of the creatures they are imprisoning. There is a theory in modern physics called the [holographic principle](https://en.wikipedia.org/wiki/Holographic_principle). It is the idea that the behavior of a volume of space can be encoded on its surface. This is easily shown to be true for light, because we can construct [holograms](https://en.wikipedia.org/wiki/Holography). The behavior of the 3d space of the apparent object is captured on a 2d surface of the holographic media. The holographic principle is the idea that this works for all physical behaviors, not just the properties of light. It is used in all sorts of neat ways. For instance, Stephen Hawking was striving to prove that black holes did not destroy information. Instead, he argued that they should encode that information on their surface. If this is true, then these godlike creatures need only provide a thin film around the creatures which encodes the state of the apparent world beyond. This structure can be as small as one wishes, as long as it can enclose the inhabitants. In theory it could be as small as our brain (or even smaller... our brain could be the illusion while our real "thinking machine" is something else). However, if its gets small, we may notice things: * If you can't create an actual holographic representation because you lack the technology or the holographic principle turns out to be false, then you can rely on false holograms like [Pepper's ghost](https://en.wikipedia.org/wiki/Pepper%27s_ghost), and the projection versions of it. These would have to be large enough to make sure we could not detect effects like parallax. Real holograms do not have this limitation. * If you have a static representation of the space (like our static holograms today), then you can only represent a static space. The individuals will start to notice that these far reaching spaces appear to simply not move. They seem frozen in time. * If you have a playback representation of space, then you can make the far reaching spaces appear to move. Any physical limitations on this playback might be detected. For example, if you play it like a movie at 24fps, people might notice a 24fps jitter, if they can take fine enough measurements. * If you have a dynamic representation of space, then there is no limit to how small it can be. The key way to notice the static and playback holograms is to try to interact with it. You can see a holograph of a beautiful woman talking on the phone, but if you try to reach out and touch her, you quickly find your hand touching a piece of plastic. This is because this static hologram cannot respond and adapt to your interactions. If you had a smart enough simulation that could generate new holograms on the fly, it could fake interactions. Once you can fake interactions, you now have [Plato's Cave](https://en.wikipedia.org/wiki/Allegory_of_the_Cave), where you cannot trust your own senses. [Answer] You don't need to set a fixed-size at the creation Initially at the creation, the universe could be as small as the Earth itself. Then, at the fourth day, God makes lights in the vault of the sky to give light on the earth. The Sun and Moon serve a practical purpose, but the stars themselves are mostly decorative. The first design might have just consisted on a sphere around the Earth, as pictured on some early conceptions. The Sun and Moon could be the only bodies moving a that point, although positioning them inside a larger Solar system would be needed for a proper design of the Sun as a burning star (instead of providing the heat in a different way). The stars could have been static leds there, but we can assume that these decorative lights would vary since quite early, with different star designs each season. Also note that sometimes new stars are lit or faded. At one point, God decides to improve the design (which already was good) giving it more depth, by moving some stars to places a few light-years away, while keeping the overall picture when viewed from Earth, this way the shades provided are slightly nicer (maybe imperceptible for humans, but God strives for perfection; and what is making the universe thousand times larger for Him?). When humans sent the Voyager probes, God would have needed to enlarge the Universe on their path out, so they didn't reach/collide with the "end of the Universe" (if it wasn't big enough already, which it probably would). Also note it would be enough that there is Universe up to wherever they reach by approx 2032 AD, at which point they will be unable to transmit. [Answer] We need to change the basic assumption of [parallax](https://en.wikipedia.org/wiki/Parallax) Stand in front of a telephone pole and look at a building beyond. As you move back and forth, you can see the pole covering different aspects of the building at different distances. Since you know your distance from the pole and the distances you're walking, you can use simple trigonometry to calculate the size and distance of the building beyond. That's parallax. But it depends on nothing we don't understand distorting the transmission of light. Scientists once felt the vastness of space was filled with [aether](https://en.wikipedia.org/wiki/Aether_theories). It allowed scifi authors to play with the idea that space ships were little different from naval ships and we could walk around on the decks. Then we started actually putting things in space. But, as we developed more complex mathematical models of our universe, some of the math didn't work. This necessitated bringing back the idea of aether. I suspect a number of scientists simply didn't want to be embarrased, so they called it another name: dark matter. Let's use the concept of "dark matter" as a lens, not unlike looking through a fluid, which distorts the flow of light over long distances The consequence of this is that what looks to we humans to be a 13 billion+ light-year sized universe could actually be just about anything you want, especially if the distorting effect of light travelling through the "dark matter" was logarithmic, not geometric. And the beautiful thing is, we're talking about such vast distances (even with a universe having a radius of only 10,000 light years) that we could easily be talking about a particle so rare that our own modern-day science has yet to actually detect its physical existence (if it exists, let's assume it does!). So... dark matter distorts the transmission of light such that the method of measuring distances, parallax, makes the universe appear much, much larger than it actually is. [Answer] Keep in mind that most of our observations and measurements about the universe assume that the [cosmological principle](https://en.wikipedia.org/wiki/Cosmological_principle) is true. That is, they assume that the laws of physics we observe on and close to Earth are the same as what we would observe anywhere else in the universe. That's a serious assumption that we don't have the capability to prove. If this assumption turns out to be false, then everything we know about the wider universe is wrong (or is at least called into serious question). If the "higher" universe that you mentioned did not have uniform laws of physics or if the creating entity had the ability to adjust the laws of physics within the scope of the "created universe", then you can get away with a fairly small universe. Imagine if instead of the speed of light being constant, it was a function that changed as you got farther away from the Earth. If the speed of light, the passage of time, the strength of gravitational forces, etc were all non-uniform like this, then an Earth-bound observer who assumed a universal set of physical laws would see the universe in a very incorrect way. A tiny universe could appear massive, or vice versa. If you can assume that your created species would never be able to travel far enough beyond their planet to detect the inconsistencies, then you wouldn't need a very large "universe" at all. [Answer] I don't know how small you can make the universe in your story without violating any major scientific laws. I suggest that the universe has to have a radius at least millions of times (possibly many times that) the farthest distance that humans can travel for humans to not discover any spherical shell with lights on it to represent stars and galaxies. I would suggest that your universe might have to be thousands or tens of thousands of light years in diameter at the present, and your god or gods might have to be prepared to enlarge the other shell and move it much farther out in the future, and replace images of stars, etc. on that shell with real physical stars, etc. at the proper distances. And quite probably be prepared to do it multiple times, as he, she, or they might have done multiple times in the past. According to the current scientific understanding of the universe based on observation and the laws of physics, the observable universe has a radius of about 46 billion (46,000,000,000) light years (14 billion parsecs) and thus a diameter of about 96 billion (96,000,000,000) light years (28 billion parsecs). Because of the expansion of space between galaxies, the light from more distant objects can never reach Earth and be seen by Earthlings because space between more distant objects and Earth is expanding faster than the speed of light. > > Because we cannot observe space beyond the edge of the observable universe, it is unknown whether the size of the Universe in its totality is finite or infinite.[3](https://worldbuilding.stackexchange.com/questions/120255/how-can-i-know-where-to-point-my-spaceship/120278#120278)[52][53] Estimates for the total size of the universe, if finite, reach as high as {\displaystyle 10^{10^{10^{122}}}} 10^{10^{10^{122}}} megaparsecs, implied by one resolution of the No-Boundary Proposal.[54][b] > > > <https://en.wikipedia.org/wiki/Universe#Size_and_regions>[1](https://en.wikipedia.org/wiki/Universe#Size_and_regions) A megaparsec is one million parsecs, or 3,261,563.777 light years. And there seem to be at least 122 zeros in that number. Thus it is possible for the universe, even if finite, to have gazillions of times the volume of the observable universe. Thus the problem of making the actually universe in your story much smaller than the universe of scientific research while not breaking any of the know laws of physics becomes very complex. And it seems to me that the main problem with trying to make the universe the size of, for example, the solar system out to a few times the orbit of Neptune, with a spherical shell around it containing images of allegedly more distant objects, is trigonometry, a branch of geometry, and its implications for parallaxes. Everyone has experiences with parallax. Hold out your hand at arms' length and hold up a finger so that it lines up with an object in the background looking at it with both eyes. If you close your right eye your finger will appear to jump to the right of the background object, and if you close your left eye the finger will appear to jump to the left of the background object. And if you line up a tree and a telephone pole, for example, and then take a step to the right, the nearer one will seem to move to the left of the farther one. As a child riding in cars at night, I often noticed the moon seeming to follow the car, disappearing behind buildings or trees and then reappearing from behind them at the same angle relative to the car as before. And that is because the Moon was usually millions of times as far away as the nearer buildings and trees and so the parallax of the buildings and trees was millions of times greater. And the same phenomenon can see with clouds and trees, buildings, etc. when riding in a car in the daytime. The clouds are thousands of times closer than the moon, but many times farther away than nearby trees and buildings, which thus have many times greater parallaxes than the clouds. Modern astronomers have developed techniques to measure incredibly tiny angles, probably down to about a trillionth of a full circle at the present, and will develop improved techniques to measure ever smaller angles in the future, which means they can measure ever smaller parallaxes of ever more distant objects. I discuss stellar parallaxes in other answers to other questions. Here, for example: [Can my spaceship figure out its position using Cepheid Variables?](https://worldbuilding.stackexchange.com/questions/122461/can-my-spaceship-figure-out-its-position-using-cepheid-variables/122492#122492)[2](https://worldbuilding.stackexchange.com/questions/122461/can-my-spaceship-figure-out-its-position-using-cepheid-variables/122492#122492) And here: [How can I know where to point my spaceship?](https://worldbuilding.stackexchange.com/questions/120255/how-can-i-know-where-to-point-my-spaceship/120278#120278)[3](https://worldbuilding.stackexchange.com/questions/120255/how-can-i-know-where-to-point-my-spaceship/120278#120278) So it seems to me that you will probably have to make stars which have measured parallaxes and distances of tens, hundreds, or thousands of light years from Earth really at those distances, and thus put the spherical shell, decorated with shining lights impersonating more distant stars, at an even greater distance from Earth. And it is quite possible that results from the Gaia satellite mean that your god or gods has already had to move the spherical shell out to a distance of tens of thousands of light years. As I remember, the distance to the Pleiades Star Cluster is very important for astronomers because it contains the nearest examples of some classifications of stars that are used as "standard candles", their apparent brightness as seen in different star clusters, etc. as compared to their calculated absolute luminosity enabling the distances of clusters containing them to be calculated. And about 25 years ago the parallaxes of the stars in the Pleiades Star Cluster as measured by the Hipparchos satellite were controversial because they were different from those obtained by less direct means and suggested that using the Pleiades stars as "standard candles' would have to be re calibrated. At the present time various studies and the preliminary results from Gaia suggest that the Hipparchos distance is an error. It seems to me that you could use various controversies about the distances of various astronomical bodies to suggest that there has been some sort of foul up in impersonating a vast universe, thus implying that the universe could be much smaller than it looks. And possibly characters in your story wonder when results from the Gaia satellite (or possibly some future successor of it) will be announced, and some may speculate that the delay is due to the observations proving that the more distant stars are lights on a spherical shell and the astronomical community is covering them up. Since astronomers can measure parallaxes out to distances many millions of times at least the length of the baseline they use, and since it would be possible to increase the length of the baseline with observations in outer space, you might have your god or gods create an invisible but impenetrable force field around Earth, the entire solar system, or the nearby stars, and then create stars in 3D space out to a distance of millions of times at least the diameter of that force field, with the spherical shell with lights to impersonate stars and galaxies being beyond those stars in 3D space. Then humans may discover the invisible force field when space probes or star ships crash into it and explode, and learn the truth about the universe. [Answer] The Hubble Radius 13.7 billion light years. Anything happening outside this radius will never reach an observer that far away. This could be modified by adjusting the Hubble constant (roughly the rate of universal expansion) in your universe. Note that current theory indicates that the Hubble constant is not constant and changes over time. This is very convenient for your story as they would still be able to see the cosmic microwave background radiation at a 13 billion year old universe. Unless... You only plan on having your humans exist for a certain amount of time, then you only have to make sure it's c\time humans exist (c being the speed of light). The universe could just stop expanding and the light from this phenomenon wouldn't reach the place where the humans are until after they are all gone. [Answer] Play with time ratio. There's no better way to fake something than no faking it at all so... don't create an universe and then tweak it in different places in order to make it look different. --- Either with a simulation or with a magic-handwaved stuff, just create the universe as big as you want and set the time speed 1.3M times faster (like pressing fast-forward on your radio tape but more extreme) wait for some thousands of years and then set the time ratio at 1 again. Then you can select (or create) a proper place for your tiny puny humans to be. Doing things this way you're less prone to errors that your humans may notice if they get smart enough like: "We learned how to measure the age of photons and this light should be 13By old but appears to be only 15Ky old, isn't that odd?". [Answer] With the idea of an all-powerful god, you don't even need a universe. You just need the perception of everything going on around an individual in the universe. This god could be creating everything as the individual perceives the world around them. This is why a pen that you put on your desk a minute ago is not able to be found when looking at your desk, until you find it again right where you left it sometime later, still on your desk. Depending on how busy you want this god to be, everything gets destroyed when it goes unobserved, so everything outside of the individual's level of perception is destroyed. So, turning the corner in a building causes the creation of the building around the corner and destruction of the building behind the corner. If you want to go even smaller, your god could simply be inputting sensations directly into a brain so it only believes it has a body and is perceiving a world an universe. Maybe god decides to change it up on occasion and make a large universe for a while, and eventually decides that's too boring. Then goes really small, and gets wore out constantly creating all the personalities and matter the individual interacts with. Decides on a medium size of the Earth + atmosphere, and simply imitated the rest. Neal Armstrong didn't actually go to the moon. He, his crew, and craft disintegrated beyond the atmosphere, was impersonated by the deity for the duration, then was re-materialized on re-entry. All the memories, materials gathered, equipment left behind, etc. was all faked by god, since there really isn't a moon anyway. All the star radiation is continually created for is humans to "observe" the cosmos, which doesn't exist. Voyager 1 no longer exists, except as an imitated data stream that the deity impersonates. Your story could encompass a history/snippets of the various points in "history" where god made these different size decisions. He could also have a brief antagonist that finds a technology to detect these changes, only to wipe them out as if they never existed. You can even go to the extreme end of the story and have god decide that his creation has run the limit of his interest and wipe it out to start over. Even during the middle of the story, you can have god take a nap, eat supper, try separate mini-experiments, all with the ease of putting us on "pause" the same we do with a video game. Maybe she even takes a few year hiatus (her time frame), and starts things up again. This could account for the middle ages. She was getting tired and annoyed, so she had everyone warring and dying of plague. Then she decides to "take a break", and when she comes back with renewed vigor and ideas, we get the industrial revolution. Everything was paused, so there's no gap in control, just a different desired direction for everything to follow. Since this is god, it can control "time", so it can closely watch a dozen different people in the same time frame. It decides to study Thomas Edison and how he competed with Nicola Tesla, but at sometime later decides to watch Tesla and see how it felt to be harassed by Edison. You know what, I think I've described a different novel than what you wanted. Sorry. Feel free to use these ideas or even write another book based on this post. This can still fit the Judeo-Christian idea of god, since we really don't know what god does, now that he's done "creating" the "universe". [Answer] Dame Julian of Norwich, a Christian mystic who lived in England in the 14th century, had something to say about this. > > God also showed me a little thing, the size of a hazelnut, lying in the palm of my hand. It seemed to me as round as a ball. I gazed at it and thought, ‘What can this be?’ The answer came thus, ‘It is everything that is made.’* I marveled how this could be, for it was so small it seemed it might fall suddenly into nothingness. Then I heard the answer, ‘It lasts, and ever shall last, because God loves it.' > > > <http://intotheexpectation.blogspot.com/2012/05/praying-with-julian-of-norwich-and.html> ]
[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/28577/edit). Closed 8 years ago. [Improve this question](/posts/28577/edit) In the book 2001: A Space Odyssey, it is revealed that creatures can evolve past physical form. Could this actually happen? Could an organism actually move beyond corporeal existence? And would this new version be called a "soul?" [Answer] Turn their consciousnesses into computer programs. [Samuel argued that there is no known way to evolve beyond using DNA](https://worldbuilding.stackexchange.com/a/28581/627), while [DaaaahWhoosh recommended artificial evolution](https://worldbuilding.stackexchange.com/a/28582/627). I agree with them both, in that I believe that nature will never move beyond physical, organic forms. However, the organisms themselves can use advanced technology to do so - namely, computers! According to [some answers here](https://worldbuilding.stackexchange.com/q/20187/627), this might be possible - at least, it might be possible to transform consciousnesses into software programs. The requirements here seem laxer, though, so I think the odds are better. To be able to say that a being has become a computer program, there are a side few requirements that must be satisfied: * The things that make the being unique (its genetic code) must be represented. This can be done by representing DNA by binary code. * The being must be able to take in input from its surroundings and influence its surroundings. This can be done by auxiliary devices controlled by the being. This emphasizes one important point: The creatures obviously still need something in order to run (namely, hardware), but they themselves are about as un-physical as possible. Whether or not this method is valid is, like all other suggestions here, a philosophical question, but I feel like it is valid. After all, would you call a string of ones and zeros physical? [Answer] No. There is no mechanism known to us that would allow a creature to evolve past the point of using DNA. It doesn't rule out the possibility that the life forms could develop machines to convert themselves into energy or whatever is "past physical form". But it's not going to be a natural process. Some might call these new creatures "souls", but it's an irrelevant designation. More likely any of the creatures remaining corporeal would have remained that way for a reason and would not treat those who have moved on with such reverence. [Answer] I think there are actually two questions here: 1. Can an organism exist that is non-corporeal? 2. Can an organism evolve to become non-corporeal? As you can see, the second question really depends on the first. I would say that as we have no examples of non-physical life-forms, it's really hard to say if they're possible. I mean, just think about it, what would they be made of? Nothing, of course. But if they are something, then what? Maybe they're made of light, or energy, or some other thing that exists that is not matter. I don't think this question can be very satisfactorily answered, so let's assume it's a yes. The next question, about evolution, brings to my mind the concept of intermediate forms. Between physical and not physical there has to be some sort of middle ground, some sort of half-physical missing link. Over many generations, your organisms will have to become less and less corporeal until there is nothing physical left. Again, without knowing the final form of this organism, it's hard to say if this could be accomplished, but I would at least like to point out that non-corporeality should be immediately beneficial in some way. If your demi-corporeal creatures can't mate with anyone, or can't defend themselves or sustain themselves, and can't do all of these things better than the competition, then it's very likely any non-corporeal mutations won't last. A far more probable method is to achieve non-corporeality through artificial evolution. Just look at humans: we developed larger brains for a long time, then in the last century we massively increased our thinking power not through evolution but through the invention of computers. For a long time, human ingenuity has achieved more for our species than evolution could accomplish in millions or even billions of years. We've even been able to create things that don't directly, immediately benefit ourselves, such as space travel. I think that if non-corporeal life-forms exist or ever will exist, it will be not through evolution, but through the inventions of a highly intelligent species. (slightly tangential)EDIT: Thinking about souls got me to considering the possible example of a human being as an intermediate form between physical and non-physical. In Christianity, animals don't have souls, and since humans evolved from animals (I realize the possible contradictions here, just go with it), it stands to reason that at some point in time humans evolved to have souls. Keep in mind that the intervention of a soul-creator such as God would fall under my last point, of artificial evolution, so let's assume God sat back and let it happen. It is believed that the soul is created upon conception, but lives on after death, so it seems like the body is only needed at the beginning of life, and may be discarded almost immediately, which sounds like we're pretty close to evolving past physicality. The thing is, the soul seems more like a parasite than part of the body. It only uses the body as a means to procreate, kind of like how a facehugger can only give birth into a human's stomach. If humans evolve to be completely non-corporeal, it would be more like the parasite evolving to be self-sufficient, but since the soul was never physical in the first place, that jump from physical to non-physical wouldn't have happened. [Answer] I'm thinking... yes. No. Depends. Can your species evolve to, as in 2001, make technology to do this? We won't know for a long time. But if you believe in 'souls,' then it could be accomplished by slowly dropping the reproductive 'creatures' down to zero. At this point, with no physical mass, they would no longer have any ability to make more of themselves, evolution's biggest spiel. But on the other hand, with no matter, or corporeal form, they wouldn't have to worry about that. [Answer] The answers to this are frustratingly dependent on the specific definitions of words that we tend to like to think need no definition, like "evolve," "existence," and "soul." Accordingly, expect no final answers. That being said, there's a tempting approach to consider for defining some of these concepts. In particular, consider what it means for a being to be "corporeal." It tends to vaguely mean they have matter, but when you consider an empirical meaning to the word, it has to deal with how things interact. We can't detect matter directly. We detect their interactions, whether gravitational or electromagnetic, or otherwise. We can see that an object is between us and the sun because we believe we should be seeing photons from the sun, and we are not seeing them. Thus, we presume something must be blocking them. From this approach, "corporeal" has picked up an interesting meaning. Now it means that a third party cannot detect any interactions they would deem corporeal. This fits quite well with the definitions needed for 2001: A Space Odyssey. A creature would be deemed incorporeal if we have no way of detecting the presence of their corporeal body. Of course, to be interesting, such a body does need to interact with the world. We can presume infinite such bodies that do not interact, but the interesting cases of incorporeal entities, such as ghosts, do interact. They just do it in a way that is hard to trace causally to matter that is categorized as "part of their body." To have meaningful interactions with the world, such a being would have to understand the world around them well enough to find ways to amplify the tiniest interactions, and then be "elsewhere" before someone can causally trace what they've done. Why might an individual undergo such a transformation? One benefit of this approach is that it is remarkably efficient with energy. One always applies the absolute minimum amount of energy possible to solve any particular problem. Interestingly enough, efficiency of energy usage is oft cited as a desire. This suggests that not only is there a possible path to incorporeality, that it might actually be along the path of any given martial art, reigion, or any other social structure which extols the virtue of efficiency. [Answer] The foremost thing to realize when discussing a question like this is that you're asking whether it can happen, which is actually a question about two things: 1. What is a consciousness/individual? 2. What do we not know about the world? And unsurprisingly the answer to both is that we don't know. Like seriously, popular media might try creating the illusion that the consciousness is just the brain and that it's all perfectly understood, but at university in our introductory course about human physiology literally every second paragraph about the brain finished with 'we don't get this yet'. We have no idea what a free will is and our theoretical deterministic models do not match the models we believe in and act by. And the same goes for the second point, we obviously do not know what we do not know, so saying what realistically could be discovered in the future is a terrible question (and yes, I did downvote the question because of this). --- But a far more interesting question and on-topic question on worldbuilding.SE is about how you can justify such an evolution in a story. The first thing to look at then is which things are mass-less (thus without material form) and then create some kind of network which at least at some level resembles the human brain. Within those boundaries you can probably come up with a justification for about anything. Let's go with light as our mass-less basis (or any other form of radiation), it can interact with other light reflect around a bit, etc. A creature in such a model would then be maybe as big as a couple of galaxies and thought processes would probably be really slow. Evolving into such a create could be either 'natural' or artificial. In the first case you could for example claim that there is a creature which emits light naturally to originally communicate and as this communication becomes more and more complex and starts to span more and more generations a point can maybe come where this network of interacting light starts to have it's own consciousness (if that's how you define conciousness in your world). In the second case it's far easier and you can simply state that either God or scientists sat down for a bit and helped such a process along. Now, all of that assumes that you wish to keep point number 2 in check as much as possible and keep the knowledge in-universe similar to knowledge in the real world. Both realistically speaking and story wise this of course entirely unrealistic, so if you want you can simply think up an alternative form of being in which a creature exists and set up artificial rules to reach such a state of being (e.g. as with Stargate). Technically speaking this could be considered more realistic than the first option, however it will feel more alien and thus unrealistic (scifi-y) to most readers. Which kind of approach you choose is all up to you, but that's the cool part about creating worlds about stuff we don't know: You have a lot of freedom, just be aware of this freedom and don't let sciencism limit you. [Answer] Maybe some species already have evolved this way. How would we know? I'm having a hard time trying to come up with a reason why a species would evolve this way. Evolution is largely driven by adapting to the environment, so what in the environment would lead to this? Evolution also takes thousands if not millions of years. During the transitional period, until we finally shed our bodies, are we going to be partly physical and partly not? The coelacanth has been around for roughly 400 million years. You would think that if any species was going to move beyond corporeal existence, it would be the one that has been around for the longest time. But not the coelacanth. Maybe it just isn't trying hard enough. ]
[Question] [ I am currently designing an alien world and I had the idea that the planet would have constant auroras nearly everywhere due to its host star. At first, I just had some ideas on how that might affect the creatures to evolve and all that but then I had the thought. Would plants be able to use the light from the Aurora to photosynthesize? [Answer] The Aussie space weather forecasters have [a page about auroras](https://www.sws.bom.gov.au/Educational/1/1/8). One line of interest: > > Bright as the full moon. Casts shadows. Very rare. > > > Now, there are two problems here. Firstly, the moon is 400000 times less bright than the sun. From [this nice answer by Willk](https://worldbuilding.stackexchange.com/a/153358/62341) to a question about nocturnal photosynthesis, you can see that moonlight at its peak can provide enough light for some photosynthetic bacteria, but not much more than that. Oho, you might say. Maybe your auroras are much brighter! Well, maybe they are, but that brings us on to the second problem. We only get auroras that bright on Earth when there's a big solar flare pointed directly at us. This is thankfully a rare event. If it were commonplace, it would simply blow our atmosphere away and we'd be left with nothing, and you'd have bigger problems than photosynthesis. Moreover, if it were commonplace the star must be losing mass at a surprising rate... not something necessarily sustainable for long enough to for a nice planetary system with biospheres. So: > > Would plants be able to use the light from the Aurora to photosynthesize? > > > Briefly. Rule of cool being what it is, you should of course feel free to handwave this in to your setting because it is awesome, not because it is realistic. If you want to make scifi rather than fantasy though, maybe have a rethink. [Answer] # If your planet has a really strong magnetic field. [This planet has very powerful aurora borealis.](https://www.space.com/30087-alien-auroras-found-beyond-solar-system.html) > > Until now, the brightest known auroras came from Jupiter, which has the most powerful magnetic field in the solar system. In comparison, these newfound auroras are more than 10,000 times — and maybe 100,000 times — brighter than Jupiter's, Hallinan said. This is because LSR J1835+3259 has a magnetic field perhaps 200 times stronger than Jupiter's, he said. > > > If you had a monstrously powerful magnetic field on the planet then yes, the aurora borealis would be monstrously strong. [Answer] (side note: Auroras are mostly green (557.7 nm wavelength) from oxygen reactions, so chlorophyll might not be the best choice for photosynthesis there, as it reflects green rather than absorbing it. Make sure you understand the mechanisms and wavelengths of your auroras, then make your plants an appropriate color to absorb those wavelengths.) As has already been suggested by other answers, there are two main variables that govern the brightness of an aurora: 1. strength of the solar wind 2. size of the magnetosphere "sail" to catch that wind Ramping both up will give you a brighter aurora. But to be worthwhile, you need the light from the aurorae to be significant compared to the sun. That's a hard challenge, but not impossible. There are some things you can do to the upper atmosphere to make it brighter. Earth's atmosphere's 78% Nitrogen, 21% oxygen, but the majority of the light from the auroras is the green from the oxygen. So increasing the oxygen a bit might help with brightness. You could also have the atmosphere filled somewhat with dust that could filter out visible wavelengths from the sun while also causing brighter auroras. This is a bit handwavey, though. Perhaps the most powerful option is a big cloud of dust. This has the advantage of obscuring much of the direct light from the sun, while at the same time allowing for far more charged particles, a more powerful "wind" of electrons for the planet to pass through, and hence a bigger auroral effect, against a dimmer star. This wouldn't work so well if it's part of the initial cloud that the planets form from: those clear up pretty fast, and to even be classed as a planet, the planet will have needed to clear its path through the dust. Another option is to bury the whole solar system in an electrically charged dust cloud/nebula - perhaps one that the sun has been passing through or colliding with for billions of years. Nebulae are very vacuous, nothing like you see in movies. No billowing clouds, no lightning. But 10,000,000,000 particles per cubic meter, compared to 1 particle for interstellar space, is still not nothing. I'm not sure it would have a significant dimming effect on a sun, but that, plus a change to solar type and size, plus an increase in distance from the planet, might all make for a dimmer sun. An emissive nebula might give you a faint background glow (a nice sort of secondary/background effect to the aurora), as well as faintly reflecting the glow of the sun all the time, even in the night-time. Something to do more serious math on before relying on, perhaps, or you could just handwave it, since impossible pea-soup nebulas are a common enough sci-fi trope. The nebula/dust and aurora might affect the distance for "goldilocks zone", too - giving more incident light to the planet, so raising the temperature. The particles in a nebular are bigger (atoms and dust particles) than the plasma of the solar wind, so it might also cause a brighter aurora. It might also cause some atmospheric warming, but if it's hard sci-fi, then do the math on that before relying on it. [Answer] Since it is an alien world, the plants are probably different from the plants on Earth. Maybe the entire eco-system is radically different - possibly silicon-based instead of carbon-based. In those situations, it might be possible to use the dim light for photo-synthesis. Also, you might want to "design" the plants to be really small and to be really leafy - to absorb as much light as possible. So I assume, no cactuses or pine-trees. Alternatively, the particles (electrons, protons...) on that planet are different than the particles on Earth - therefore physics and chemistry as we know them do not work any more. ]
[Question] [ I'm trying to figure out if it would be possible for a group of people living in the wilds of a post-apocalypse USA could find some useable weapons and/or ammunition. The post-apocalypse in question is essentially one where monster-like creatures have overrun the world, and twenty to thirty years later, they hunt what's left of humanity, but not really focusing on destroying any existing buildings or structure save for a few places where they build their "nests." Would it be possible for the survivors to find bullets or guns just lying about or maybe in some kind of storage facility? I think I remember reading somewhere that the United States made over ten billion bullets a year, so I thought maybe it wouldn't be too unrealistic, but I'm not sure. So given the context of the setting, what would need to happen to make finding useable weapons and/or ammunition a realistic possibility? [Answer] Some variables need to be established in order to come up with a sensible answer. The first question is geography. In some parts of the United States, local governments have imposed various restrictions on ownership of firearms. Other localities might favour shotguns, or large calibre hunting rifles (for deer, moose etc.), AR-15's (shooting small game or "varmits") or handguns (urban areas). So characters are not going to go around like kids in a gun store and just pick up what they need - they might only find weapons which are of limited utility for them, even if the former owners were satisfied. The second issue is ammunition. Ammunition needs to be carefully stored otherwise it will degrade. Ammunition sealed in metal ammunition cases is probably ideal, but factory packaging that resists moisture is second best. Ammunition stored in relatively temperature controlled environments will also last a long time. Otherwise, the primers and propellant will begin to deteriorate, and the casings can also corrode (especially things like Russian steel cased ammunition - lots of surplus Russian ammunition was sold starting in the 1990's to go with things like SKS rifles). [![enter image description here](https://i.stack.imgur.com/WFKBC.jpg)](https://i.stack.imgur.com/WFKBC.jpg) The best way to store and carry ammunition The third issue is just what sorts of weapons are needed. "Monsters" are probably not going to be affected by .22 Long rifle ammunition, but keeping your game pot full might depend on your skills with it. Human predators may be deterred by a .22, but you will really need something more powerful to ensure the target stays down when hit (.38 for handguns is about the minimum. .223/5.56 X 45 has become almost ubiquitous in the US for AR and Mini-14 style weapons, but .308/7.62 X 51 is a far more reliable choice. Larger calibres are also needed for larger game, or to reliably engage at long ranges. [![enter image description here](https://i.stack.imgur.com/0V9qq.jpg)](https://i.stack.imgur.com/0V9qq.jpg) Good for big game, not so much for rabbits Movies and political myths aside, fully automatic weapons are not available to civilians in the US, except under very tightly controlled circumstances (essentially the trade for the very limited number of "grandfathered" weapons which are now collectables). Military armouries and police stations will be where these can be found, but over the decades looters will have been using bulldozers to knock down the vaults and without proper training and fire discipline, the ammunition may have been blown away in blazes of glory. Carrying a belt fed machine gun is a pain due to the size and bulk, and even a proper automatic rifle like an M-4 will require a load carrying vest capable of holding 10 magazines if you are serious about using automatic fire. [![enter image description here](https://i.stack.imgur.com/PT7sP.jpg)](https://i.stack.imgur.com/PT7sP.jpg) There's a reason they dress like that When you get down to it, any competent machinist can make a firearm with hand tools (the Sten gun from WWII was designed to be built that way, and Pakistani gun smiths can make replicas of virtually any firearm you can name). Hand loading ammunition is possible so long as you can collect the casings and have access to the tools and chemicals, so you are not just limited to scavanging. In a really post apocalyptic environment, it may even be more sensible to make or find a black powder firearm, as your ammunition resupply will be easier to solve (you can make your own gunpowder and even your own shot or ball projectiles). [![enter image description here](https://i.stack.imgur.com/Z9e58.jpg)](https://i.stack.imgur.com/Z9e58.jpg) The AK will be ready next week [![enter image description here](https://i.stack.imgur.com/qqVrQ.jpg)](https://i.stack.imgur.com/qqVrQ.jpg) Your ammunition will be done shortly. You said 15 cases, right? The other avenue of approach is to relearn the art of making bows, especially longbows (warbows with 100 lb draw weights) or steel crossbows (using a spanning mechanism, you can have up to 1200 lbs draw weight). These bypass issues like ammunition (although you still have to find or make arrows or quarrels), and are much quieter than firearms as well. Bodkin pointed arrows or quarrels could penetrate mail armour, so should have some effect on monsters, unless you are fighting Godzilla, in which case even a Barrett light .50 rifle is pointless. [![enter image description here](https://i.stack.imgur.com/hA7WJ.jpg)](https://i.stack.imgur.com/hA7WJ.jpg) Making a longbow is an art [![enter image description here](https://i.stack.imgur.com/skHTN.jpg)](https://i.stack.imgur.com/skHTN.jpg) At 1200lbs draw, things will be uncomfortable for the target [Answer] The real trouble isn't the deficit in small caches of firearms and ammunition. Others have pointed out that the United States has more than plenty of these things. The problem is that, in an event that allows monsters to overrun the US (not just invade it), likely much of that will have been exhausted in the initial fighting. If we were to plot out the remaining ammunition along a curve, we even know what shape it must be! The only unknown factor would be along the x axis and how far in the future it approaches zero. If fighting (or hiding from) these monsters is a matter of survival, and if only small pockets of humans remain, then we have a situation where most people went down fighting (and presumably expending ammunition). If instead they didn't even have a chance to fire and could leave behind large caches of ammunition... what has changed that ammunition will do any good for your characters in the story? I suspect strongly that they will occasionally stumble upon small caches. A box of handgun ammunition, a revolver with a few unexpended rounds, things like that. But these will likely be on the order of once every 6-24 months. Not daily, and never in quantities that will make them comfortable. As for weapons themselves, any firearm that stays out of the elements and avoid significant rust will either be serviceable or can be made so with basic tools and know-how. But without ammunition they will be little more than paperweights. [Answer] Yes, easily. I think most people don't quite understand how many guns there actually are in the USA. Here's the fact: For every 100 people in the USA, there are around 120 civilian owned firearms. This means that, on average, every man, woman, child, and baby in the USA owns 1.2 guns. The house with a nuclear family in it has five guns in it on average. If I searched a US neighborhood and did not find at least one gun in a safe, I'd know that I'm experiencing a severe localized statistical anomaly. [Answer] # After a few decades, Yes There are two sides to this problem. Ammunition, and firearms to fire them. Both of them should be fine as long as it's only a few decades later. # Ammunition I admit I didn't actually know this, so I asked Google. [This guy](https://www.activeresponsetraining.net/old-ammo-will-it-still-work) has fired off some ammo significantly older than the time frame you're contemplating. He seems like the closest thing to an expert that I could find: a police officer assigned the task of disposing of old ammo people drop off because they don't want it in the house anymore. According to what he wrote, your characters shouldn't even have to worry about how to make new ammunition (which is a thing that probably can be done). > > The only problems I’ve ever had with ammunition not working is when I try to shoot old shotgun shells…especially the paper hulled ones. A great majority won’t fire. It must be the difference in primers between the shotgun and handgun ammo or the fact that the paper hulls attract moisture. > > > As a general guideline, you should never shoot ammunition that: > > > ``` Is corroded Is misshapen and doesn’t fit into the chamber easily Has the bullet pushed back into the cartridge Is rusty Has a cracked case ``` > > If it doesn’t have any of these characteristics, it’s probably safe to shoot. One additional caution: if an old round doesn’t immediately fire, keep the muzzle pointed downrange for about 10 seconds before clearing the gun. Occasionally, old ammo “hangfires” which means there is a delay between the striking of the primer and the detonation of the gunpowder. If you have a batch of ammo that is hang firing, I would not shoot any more of it. > > > # Weapons themselves There are plenty of folks out there who know how to make replacement parts and have gunsmithing tools. So even repairing firearms shouldn't be a problem. [Answer] Yes. The best places to check would be storehouses, followed by factories, gun stores, and armories for police or military forces. But these places would also be obvious to other survivors, so that may complicate it, whether they have already been looted, or the other survivors are still there. (This assumes a short time frame. Chances that something went wrong increase with every passing year, of course, making it more difficult.) [Answer] As John O said, ready-to-use ammunition will quickly become rare. But it's not hard to refill your own cartridges. Plenty of people do it now, sometimes it's cheaper than buying new ammo. I would check outdoor shooting ranges. The firing line will probably have some empty brass lying around, and the backstop, if it's dirt or sand, will probably have tens of thousands of bullets in it. You can easily sift through the dirt to find it. ]
[Question] [ In my book series (more on that [here](http://sites.google.com/site/weaselworldofficialsite)), the galaxy is inhabited by anthropomorphic animals, humans, and mythical creatures. The anthropomorphic animals are similar to Narnia's talking animals, except they are given an anthropomorphic design (their upper 2 limbs are made into arms with opposable thumbs, they stand on 2 legs, and they wear clothes). However, I've run into a bit of a problem: anthropomorphic snakes and eels. How would these limbless creatures be able to move around anthropomorphically and be able to carry and manipulate objects? I don't want to just give them arms because that just makes them look weird and ruins the aesthetic. PS, magic exists in this universe, but VERY few people have access to it, so magic is not a viable solution to this problem. [Answer] Prehensile tail. [![kaa from Jungle book uses prehensile tail](https://i.stack.imgur.com/R0cRF.jpg)](https://i.stack.imgur.com/R0cRF.jpg) <http://www.michaelspornanimation.com/splog/?p=2014> Here, Kaa from The Jungle Book demonstrates how it is done. The tail of these limbless creatures is used to grab, wrap, poke, tickle and all the other things one might do with a finger or tentacle. [Answer] Well, snakes used to have four legs. This is, I believe, a skink, but you get the idea: [![enter image description here](https://i.stack.imgur.com/woGH3.jpg)](https://i.stack.imgur.com/woGH3.jpg) Here's a fossil of a four legged snake from Brazil: [![enter image description here](https://i.stack.imgur.com/GK5j0.jpg)](https://i.stack.imgur.com/GK5j0.jpg) So, holding things would really not be at issue if you decided to go this route. A typical image of an anthropomorphic snake~person might look like this: [![enter image description here](https://i.stack.imgur.com/W6Fgc.png)](https://i.stack.imgur.com/W6Fgc.png) But in the literature there are depictions of limbless snake~people: [![enter image description here](https://i.stack.imgur.com/DxkJ1.jpg)](https://i.stack.imgur.com/DxkJ1.jpg) I would suspect the hair is such a mess because, well, there's no way this poor person can get it anywhere near a brush or comb! [![enter image description here](https://i.stack.imgur.com/DpmFI.jpg)](https://i.stack.imgur.com/DpmFI.jpg) I rather suspect this one has a friend who's a hair dresser. But these poor lasses lack the ability to manipulate objects! So, without further ado, kindly allow me to introduce . . . Ophiunculla, an armless medusoid! [![enter image description here](https://i.stack.imgur.com/XOzFP.jpg)](https://i.stack.imgur.com/XOzFP.jpg) Nether regions of a serpent; upper stretches of her medusoid cousins, but in more snakey fashion, lacks limbs of any kind. But unlike her medusoid cousins that have arms, Ophiunculla has practiced very hard learning how to control the snakelets that grow from her head. These, she has discovered, are able to reach out and grasp objects, manipulate them and singularly or collaboratively, quite literally do anything her two armed cousins can do with their hands! As you can see, she's getting ready for her morning slither through the park. She's got her ophicomb in one snakelet, a stylus for jotting a quick geopoetical note in another snakelet, her cup of morning joe in a third snakelet, her mirror and favourite torc in a fourth & fifth. [Answer] I've noticed that for many animals, when they need to carry something they'll carry it in their mouths. I'm not sure if that goes well with the aesthetic. If they're sufficiently technologically advanced they might use some kind of cybernetic implant that gives them short-range telekinesis. H [Answer] Many options: * With their mouth * With their tail * with an special robotic exo-skeleton that have arms * Telepathically * my favorite: after conquer Earth (or a similar planet) and become our reptiles overlords (that I, for one, welcome) they can have a human minion walking by their sides carrying around whatever they want. [Answer] I agree with the mouth / tongue manipulation, but would like to add the magic system into this. You wrote: "@Sasha magic exists but using it for this purpose violates this universe's incredibly complicated magic system." Until you elaborate about this (partial?) restriction, here are some suggestions: * Use magic/snake-ish hypnosis to posses others, get them to do stuff for ya * Interface with one tool (can be magical or not) that controls other tools (e.g magical floating hand) * "communicate" with the items you want to control. Say that all things have a "soul" and a tiny bit of intelligence, and you can magically convince them to change/move * Magically control air/liquid pressure to move things * etc, etc. If Stephen Hawking can do it, so can you. [Answer] Could they have pouches on their torsos that allow them to carry things? These could be there via evolution, genetic engineering, surgery, or something less invasive. A mouth and/or a prehensile tail could put items in and out of the pouch. This would allow them to travel carrying an item with them. The manipulation of the item while they are still would still require the mouth/tail or something else. ]
[Question] [ Due to the outcome of this question ([Is there any way to Terraform Ceres?](https://worldbuilding.stackexchange.com/questions/114875/is-there-any-way-to-terraform-ceres)) I am now working on the concept of shell worlds. Docking would be done by large spires with adjoining rings where once the ships initially dock they are brought into some form of lot (this part is done by moving platforms and the ship lots being built into interchangeable grids with grids for each of the average ship sizes and some wiggle room) My question is the docking itself. Is there anyway to dock a ship safely and with minimal jolting and then be able to drag said shop into a station preferably using that same system? Notes: Hegemony engineers want a system that is able to accommodate virtually any ship via interchangeable parts. Also Ceres does spin slowly to simulate gravity. How fast "slowly" is I have no idea. [Answer] Ships boats. [![ships boats / age of sail](https://i.stack.imgur.com/o3BRP.jpg)](https://i.stack.imgur.com/o3BRP.jpg) <https://www.pinterest.com/pin/213217363586950409/> The question of safely accommodating a big delicate ship in port came up during the age of sail. These large ships were not very maneuverable in close quarters, and did not want to risk damage coming close to a port. Nor did the port want to risk damage by the ship. Instead, small boats went back and forth between ship and shore. <https://en.wikipedia.org/wiki/Ship%27s_boat> > > One of the main roles of a ship's boat was to act as a taxi to move > stores and people between shore and ship, and between ships. > Although some boats were general purpose in nature, boats such as the > Captain's gig and the Admiral's barge were for the exclusive use of > officers. It was also the role of a military vessel's boats to act as > landing craft, to deliver boarders and cutting-out (night attack) > parties. > > > When a ship was becalmed, mastless, run aground or otherwise unable to > move, a ship's boat provided a source of motive power. The ship's > anchor and cable would be rowed a distance from the ship before being > laid, the crew would then man the ship's capstans to haul the ship > forward, known as kedging or warping, this would be repeated as many > times as needed. > > > The ship's boats could also when needed be used as a lifeboats and > rescue boats. > > > Your varying spacecraft could be fitted out with more standardized and maneuverable all-purpose boats. I like the idea of these space boats filling more than one role over the course of a story as was true for the ships boats described above. I also like the idea that even in space, they are still called boats. [Answer] The standard solution - adopted on the ISS - seems to be a [robotic arm](https://en.wikipedia.org/wiki/Mobile_Servicing_System) with some sort of berthing interface on it. If the Hegemony only allows ships with 'Grappling fixture H-8' to dock, surely most of the vessels would be equipped with the standard interface. Docking to a spun-up dwarf planet is harder, but I think it is managable. As explained in this [article](http://sciencevshollywood.com/is-ceres-station-on-the-expanse-on-the-verge-of-falling-apart/) (discussing Ceres from the Expanse), on a spun up asteroid surface velocity is greater than escape velocity (if you drop something, it wont fall back down or orbit the body, but end up on solar orbit), so the reverse process is also possible: You approach on a carefully tuned hyperbolic course almost touching the surface, and on the periapse, while being relative rest to the structure directly underneath you, the ship can be safely grappled. [Answer] I think you raise a good point about the difficulty of a space station having to accommodate a wide variety of spacecraft, especially if your setting has realistically bulky ships. If standardized construction isn't enforced, you would have to try to accommodate things like this: [![a long and complicated spaceship design with many parts extruding from the core of the ship](https://i.stack.imgur.com/FgAKf.jpg)](https://i.stack.imgur.com/FgAKf.jpg) And this: [![a roughly round spaceship made up of multiple differently sized rings with holes at various positions](https://i.stack.imgur.com/gvt66.jpg)](https://i.stack.imgur.com/gvt66.jpg) In the same hangar. To me, the best solution would be to not use a hangar at all. After all, current hangars are typically used by aircraft and cars to protect them from bad weather. Space ships simply wouldn't need any protection, as they are in the same environment they are always in. It's like putting a roof over a harbor to keep the boats safe from rain; it's just not needed. Instead, having the ships "park" outside the station (while matching the station's rotation) would be a lot easier to manage. However, I agree with you that trying to dock a skyscraper-sized spaceship in the same way we dock ships with the International Space Station would cause problems, such as accidentally bumping the space station or "double parking" when the huge ship blocks multiple airlocks. So how about a souped-up version of these: [![real-world image of an airplane being boarded](https://i.stack.imgur.com/Tpros.jpg)](https://i.stack.imgur.com/Tpros.jpg) A Jet Bridge could be extended from a station towards ships to latch onto their airlocks while keeping the ships a manageable and safe distance away. Maybe having multiple bridges per ship would be ideal, so passengers and cargo could be unloaded simultaneously. The interior of these space bridges could either be long, null-gravity hallways for passengers or the equivalent of a conveyor belt to help unload cargo speedily. Of course, space Jet Bridges (space bridges?) would have to be much longer and more flexible then the ones we use. When I mentioned this device in my story, I straight up compared them to an octopus' tentacles. This is less answering your question and more providing an alternative, but I think it might be useful to you. [Answer] I would have ships put into a parking orbit. Space ships are probably more delicate than the wooden ships of the age of sail. They are also capable of more damage to a station than the wooden ships. I'm only thinking about large ships here. Think of an engine powerful enough to move a huge space ship. Let's go space opera and think about a roughly spherical ship 1 mile in diameter. Even if you discount any weapons on the ship, the force from it's engine would probably destroy quite a bit of the station if it were set off on purpose or by accident. The think of any weapons that on on the ships. Even if these weapons are illegal, somebody will have armed their ship. An energy weapon powerful enough to hurt another ship at ranges measured in hundreds of kilometers would probably cut through the station like butter. In the real world terrorists have used stolen vehicles as bombs and missiles against property and people. I'd have my stations armed against any boat (a landing craft) trying to get close without permission, and if a ship tried it, the station rules would have it be destroyed if it got past a set limit. Perhaps the limit would depend on the size and velocity of the ship (larger and more dangerous ships might be required to park further away). Large ships might be very difficult to dock anyway. Another problem might be even worse. Are their alien ships in your story? It might be difficult to explain the engineering specs of the appropriate landing gear to an alien. Then there is either pilot or computer error. A very small group of errors could cause a simple docking to turn into a crash. [Answer] If you've spun it up to produce internal gravity, then there will be a null-g area along the axis of rotation. Put a door at either or both poles. Sufficiently fast spin will keep the atmosphere glued to the walls and you can have an airlock if necessary to keep lossage to an absolute minimum. Then the docking ship just matches its own spin to the asteroid's spin, flies in, and lands gently on the elevator pad at very low g. Once everything is settled the elevator can descend, taking the ship down to the high-g, high pressure area for convenient loading, unloading, or maintenance. For larger ships that can't land, put a spin decoupler at one pole so they have a stationary dock and have a tram system that moves from the stationary section to the rotating section and back via simple braking. You'll need station-keeping engines of some kind to keep the relative velocities within bounds, but you'll need those to keep your station pointed the way you want it to anyway. [Answer] I would prefer good ol' landing. Ceres is small enough to have a 0.029g at its equator, which means that you can safely land and take off with a minimum consumption of fuel, and with few risks. Since you had thought of terraforming it, why not instead start digging for installations under the surface? This would allow extensive mining and a safe harbor for the crafts. [Answer] Weight and Deceleration is your main problem A typical space probe in todays era launches and begins its journey, gaining speed at various gravitational slingshot points, it's path being meticulously worked out in advance. The voyage often takes months, or even years. During this period the speed of your ship is really fast, like 17km/s fast or so - otherwise your ship would take forever to get to its destination. On arrival, normally if there is an atmosphere you can use atmospheric breaking to slow your ship down. If there is no atmosphere to speak of, you need to slow down using engines. Sounds like your ships are really big - and heavy. It stands to reason you need to carry inordinate amounts of fuel to slow it down from such super-velocities. However in the 1960's Apollo missions they came upon a solution. A direct ascend and descend craft on the moon is simply not feasible because of the problem above, however it was discovered a possible solution to this problem is to remain in orbit, as a 'parent' craft, and then only send down what you need in light-weight landing craft. This saves weight, and saves fuel and makes the journey possible. [![enter image description here](https://i.stack.imgur.com/nC0fm.jpg)](https://i.stack.imgur.com/nC0fm.jpg) The Lunar module was developed specifically for this purpose. Every aspect of it was about saving weight to lower the amount of fuel for deceleration - even the number of legs were discussed as being 3 instead of 4 (they settled begrudgingly on 4 in case one failed). A similar landing craft with landing pads on your planet would be the most logical - with parent craft (like the Apollo Command Module) remaining far out in orbit. [Answer] My reaction is that for ships of any significant mass or size, letting them inside your station or hard-coupling them to it requires a world populated entirely by sane, competent, well-rested, trustworthy, benign humans flying around in enormously complex, powerful and nearly infallible machines. Does not sound like this universe. The answer that mentioned big sailing ships and saltwater ports seems very much on-target. If it was my station, I'd insist that any ship bigger than a vac-suit approach VERY slowly and carefully on a nearly-tangential path (maybe even under station control?) and then I'd allow it to be grappled by a long, modular, powered hollow arm that doubles as a jetway and service corridor. Each arm has autonomous onboard power and AI. Only when the arm trusts you will it grapple your ship, and if it ever changes its mind and suspects you or your ship are a danger to STATION it will toss you away like a bad apple. If a ship is staying longer than it takes to unload & load, the arm could transfer it to a simpler 'parking' stand - while still keeping a close sensor suite on it. Seems like there would be all kinds of stresses and angular momentum issues - you might have to mount the arms on reinforced world-girdling ribs for example, or pump megaliters of water (which you'd want to have anyway) around inside your station to keep things nicely balanced. I figure if my washing machine can do that, so can Ceres. ]
[Question] [ Could a medieval town have been built on the desert facing side of a mountain range? Not a Himalaya size mountain, but definitely at least Rocky Mountain size. It's a big desert and is one of the reasons that a nearby empire stopped pushing that direction. I want the town to be somewhat of a border town/outpost, but I want its existence to be practical and not just random. [Answer] Absolutely possible. Really do need to know how many people you want to support. A typical Medieval town can range greatly in population, but this could certainly support a few hundred people. Take a look at the answers to [this question](https://worldbuilding.stackexchange.com/questions/3404/i-want-a-big-city-in-the-desert-what-conditions-make-it-possible) right here on stack exchange. As long as you have the basics, food, water, and all that it's certainly possible. Because it's right by a mountain range, water might actually flow through this area, and it's even better if you have a spring. Just because an area is desert doesn't mean that there isn't a water supply present. They should be able to grow or trade for food. The mountains are really the only difference between your question and the other (which is actually marked Medieval in the tags). To answer the population question, take a look at [this question](https://worldbuilding.stackexchange.com/questions/77600/in-a-medieval-setting-how-far-apart-should-towns-be/77604#77604), which is about how far apart Medieval cities tend to be, but my answer there covers population as well. Keep in mind that the conditions you outline would mean that it might be far from other cities/townships but the next small town could be situated in the valley through the pass. Because conditions for farming aren't as good, naturally your town is going to be further away from other places--more like the 10 mile limit in Giant Cow's answer. And there probably won't be anything out further if there's a lack of resources. The other thing you might want is...something on the other side of the desert that people want to get to. It's a good reason for your outpost to exist. That something can be trade with another nation or something else entirely. Desert conditions vary widely--so it doesn't have to be your classic Sahara-- or it can have a transition to different types of desert. See this link for [more info](http://www.ucmp.berkeley.edu/exhibits/biomes/deserts.php). [Answer] Your city can be an oasis on a trade route. Travelers going one direction are about to brave the desert after making it through the mountains. Travelers having made it through the desert need to get through the mountains next. Either way these travelers need someplace to rest and change up their gear for the next leg of the trip. On the ancient Silk Road, the city of Kashgar was this place. <https://www.britannica.com/place/Kashgar> [![kashgar old city](https://i.stack.imgur.com/wcEJE.jpg)](https://i.stack.imgur.com/wcEJE.jpg) <http://antiquity.ac.uk/projgall/gilad321/> [![kashgar map](https://i.stack.imgur.com/c6Y9K.png)](https://i.stack.imgur.com/c6Y9K.png) > > Kashgar lies at the western end of the Tarim Basin, in a fertile oasis > of loess (silt deposited by the wind) and alluvial soils watered by > the Kaxgar (Kashgar) River and by a series of wells. The climate of > the area is extremely arid, with variable precipitation averaging > about 3 inches (75 mm) per year (most falling as rain during the hot > summer months). Kashgar’s historical importance has been primarily as > a trading centre. Situated at the foot of the Pamirs (mountains) where > the ranges of the Tien Shan and the Kunlun Mountains join, Kashgar > commanded historical caravan routes—notably the famed Silk Road > westward to Europe via the Fergana Valley of present-day Uzbekistan, > as well as routes going south to the Kashmir region and north to > Ürümqi (Urumchi) and the Ili (Yili) River valley. > > > Kashgar is in the rain shadow of 2 different mountain ranges but has water, probably ground water originating in the mountains. That fact and its site on the confluence of trade routes are the reason for its location. [Answer] Whyever not? For instance places like Petra <https://en.wikipedia.org/wiki/Petra> which long predates the medieval era. Or all the pioneer towns on the east side of the Sierra Nevada (North America), most of them built with tech that wasn't that much beyond medieval. You just need to be selective in your location. The town will need to be located on a water source, an oasis or system bringing water down from the high-elevation snowpack. (And these can be rivers of moderate size, e.g. the Truckee, Carson, & Walker rivers on the east side of the Sierra.) Then for any sort of major town, you need something like trade routes and/or mineral wealth to provide a reason for more than subsistence farming/herding. [Answer] Yes. With "desert facing side" you are implying the desert is in the rain shadow of the mountains and that means it rains on the mountains. Which means there is useable amount of water running down from them. Most of the water rains on the other side, but there should be ground water available and probably even small rivers running to salt lakes or flats. So the particular area might have enough water to support irrigation and have a fairly large population. It might have a large urban population of craftsmen as well as it would probably be the ending point of any trade routes across the desert as one of the few areas of plentiful food and water on the "near side." [Answer] Desert is defined by amount of rainfall received in a given year. (<10 inches, I believe). Water can be quite abundant in aquifers underneath deserts. Here's [one example](https://en.wikipedia.org/wiki/Nubian_Sandstone_Aquifer_System) - there are plenty more. The answer to your question is yes. [Answer] Look at the Front Range of Colorado. Not a desert, but it gives you good parallels. If the mountains are RIGHT THERE, you have access to the water, vegetation, habitat for animals... traveling along the mountains on the desert side is easier, you can see for a very long way... so you have feasibility and a good reason to be there... harder to defend if invaded from the mountain side, but probably not to detrimental. Its seems practical and reasonable. [Answer] Simply being an entrepot on the frontier of an empire is economic reason enough to support a town or even a significant city. Just because it is on the dry side of the range doesn't mean that it has no water. Unless the range is a monolithic wall, it is easily possible that a major river flows though a gap and away down the dry side. The desert could be like Egypt with a single river flowing through it forming a single corridor of trade and communication with your town at it's head. [Answer] The desert may well be a practical obstacle for the empire, but it doesn't mean no-one crosses the desert - it just means there's no incentive for the empire to own it. It can still be the empire end of a trade route, and as such it's a perfectly sensible place for a city to develop. Of course you need there to be no strong incentive for the empire to cross the desert, meaning the country on the other side should be at least neutral or ideally friendly. It's probably a good idea for both sides to have things that each other would like, so that it's not all one-way traffic. ]
[Question] [ Let us imagine later medieval society, very close to our 15 century society. This society struggled with Great Plague. The legends say, that they signed a pact with some supernatural forces, and the Plague vanished. But in exchange, the supernatural forces made every 10th child to become werewolf in later teen years. Let us assume, that lycanthropy is some sort of disease. How can I make this disease to be non affected by genetics and gene inheritance? So, in family that have no werewolfs, there can be a werewolf child. Or 2 werewolves can have normal child. The werewolf disease is not contagious, or people learned how they could avoid being diseased by werewolves. And the society have developed a means to control lycanthropes - lock them in cellar when moon is full and other means, so they usually do not perform bloodbaths every month. So, by what looking realistic means can every 10th child become a werewolf? UPD: some clarification: every 10% of all population are werewolves. I mean everyone who turns 18-20 years can became a werewolf with 10% probability, it does not depend on his/her parents/grandparents/siblings being werewolves. UPD1: some later clarification that was derived from answers. 0) Werewolfs are real, it is not a delusion. They do not shapeshift or grow fur, tooth and claws, but they are very quick, strong, feral and bloodthirsty. Probably they can be killed by non silver weapons, but there is quite few brave ones that would like to test it. In 99% cases werewolfs are locked in cellars or closets when the full moon is shinning. When the moon is out, werewolves are ordinary people (but probably stronger, healthy, hairy and dog smelling), that can easily coexist with normal ones 1) Lycanthropy tendency can be genetic one, but it manifests with nearly 10% probability, and the current science level in this novel do not allow to predict, if person will be werewolf, or not. 2) This disease was later cured by some mid XIX century scientific approach - antibiotic extracted from fungus for example, or specially processed extracts from `wolf blooms`. 3) I agree, that it will be more funny to manifest lycanthropy at puberty age, great thanks for mentioning this! 4) It can be some environment agent like `wolf blooms` to trigger and stop effects and microbial parasites in bloodstream, present in 100% of population, and active in werewolves only. 5) The microbial parasites emerged from some nearly instant mutation of Plague pathogens (yes, it can be magic, but the clear origins of this shift is beyond the scope of story) So, as i have stated in this update, does this way of events looks realistic? [Answer] Start with it being a genetic disease with 100% saturation across the populace. That gets rid of the vector issue. Now the issue is to explain how 90% of the populace do not exhibit symptoms of the disorder. Something must be suppressing the symptoms in almost all of the population and it must be something permanent. Once a person encounters the suppressing agent, they will never again exhibit the lunar transformation but they will still carry the disease and pass it on to their children. Two additional factors need to be brought into play to truly match your scenario. The disease must be linked to puberty, such that no symptoms ever express themselves until the child reaches their late teens. Similarly, the suppressing agent is only effective prior to puberty; whatever biological mechanism keeps pre-pubescent's from transforming gets made permanent by the suppressing agent, but only while it is present and functioning within the child. Once the hormone storm modifies that biological mechanism, the suppressing agent cannot bring it back or make it functional again. So what is the suppressing agent? It should be environmental but not linked to any class, career or lifestyle. It should be omnipresent enough that 90% of the populace encounters it in their early years, but there should be no detectable pattern to the 10% who do not encounter it. There are several ways to arrange this... The suppressing agent could be multi-component. That is to say that two or more agents must be encountered for it to work. Inhaling the pollen of a certain type of tree and then alter drinking water that is tainted with a particular algae. Almost everyone would encounter at least one of the components, but some might not encounter both. Since the lunar transformations encountered later in life are tightly tied to the phases of the moon, why not make the suppressing agent moon-bound as well. Perhaps a night blooming flower, which only opens at full moon is both a trigger to grown-ups and the suppressing agent for the young. Similar to how the drug, Ritalin has nearly opposite effects when administered to children as to adults, perhaps this flower's pollen is both curse and cure. For those who encounter it early it is a boon. For those who don't, a deadly bane. Considering that our biochemistry changes with our moods, our sleep-levels and our attitudes, perhaps the suppressing agent is only effective when encountered by children who are hungry, or scared, or tired. Every child experiences each of those states repeatedly throughout their lives, but not every child has been ...hungry on a sleepless night, when the moon is full, when the wolfs-blood flower blooms, and a cold wind cries from the northern hills... [Answer] The easiest route would be to have lycanthropy function as a normal disease. The following would cause 10% of the population, upon reaching late teens, to become werewolves: The disease has a high rate of transference; it is airborn, and even those immune to the disease will be carriers. The disease is widespread, and can live in many hosts. The result is that effectively 100% of the population would be in contact with the disease from birth, and thus contract the disease as children. The disease would be almost impossible to avoid; modern medicine may be able to stop it, but in Medieval times, it would be absolutely impossible. The first symptoms of the disease would seem like a normal baby illness: low fever, general fussiness, but no other obvious effects. In some children, it may not even be noticed. In the course of the illness, 90% of the population develop antigens, which clear out the infection and provide permanent immunity. Those that fight off the disease and become immune will not become werewolves; those that do not become immune after first contracting the disease will remain infected their entire life. The disease will remain dormant in the 10% of the population that does not develop an immunity, until their body stops producing growth hormones. Apart from those with rare genetic disorders, most people produce growth hormones until their late teens or early twenties. When those without immunity stop production of growth hormones, they will be hit with the second stage of the disease: the disease rapidly modifies DNA, which causes all the effects of a werewolf. The result is that 10% of the population at any given time will be werewolves. No one knows who will be a werewolf until the first time they change; for the vast majority of werewolves, this will be in the late teens or early twenties. Being a werewolf doesn't preclude your children to be werewolves, not does having immunity protect your children from becoming werewolves. [Answer] Lycanthropy can be a disease with so long incubation period (20 years) that people cannot see the connection. For bonus, add some culture: every child need to be recognized/counted by the Guardians every year, during which process they are marked and reinfected. Could be part of standard required schooling. Not having the mark will be capital offense, and consequence will be delayed by decades. Guardians might not be aware that they are transmitting the disease - they are just performing the rites as required. Because 90% of the treated will be OK, it will be hard to see the connection. And it might be also infectious, so even non-marked will get the disease if in contact with marked and infected parents/adults, to add the confusion. To make sure everyone is infected, make lycanthropy protect the carrier from some other, more deadly disease. Say, make non-infected people sterile, so there is darwinian pressure to get infected, and pay the price. Key is long incubation period. Any benefit, like protecting from other disease, is just frosting on the cake. [Answer] If a curse is like a disease then yes it is possible that not all individual in the population will develop it. Population here simply refer to a group of people. Actually, 10% of the population is a lot of people. Some diseases are present in the gene of an entire population is because the gene is present in the population. people might develop symptoms or not. Some develop more severe symptoms than others. Non genetic transmission : Environment: The disease can be present in the environment but people are unaware of it. At the time, medicine was less advance than it is today and they have no idea of what is going on. The diseases affects some people, other are immune or show only minor symptoms. Some might also catch it but without developing any symptoms. Cultural: Yes this seems strange. but I was thinking how Ebola was transmitted. During the funeral rite, in these African countries, they need to clean to body. But by doing so, they are spreading Ebola because the hygiene is too rudimentary. I guess we could image something like that since you mentioned that it happens at a specific age. People need to do something that exposed them to the disease without knowing it. It could be eating something, going somewhere or some sort of blood ritual. The last one in particular is a good way to get into trouble with or without lycantropy. [Answer] Your description actually reminded me of [genetic resistance to malaria and sickle-cell anemia](http://en.wikipedia.org/wiki/Genetic_resistance_to_malaria). (It's actually very fascinating.) I think you may be able to drag and drop from that wikipedia article to your problem case. Just like some of the people who are naturally immune to malaria also become sick with sickle cell anemia, some of the people who survive your plague are going to be susceptible to this lycanthropic condition, whatever triggers it. (Perhaps something environmental, like a mold that most people don't even notice.) As a plot twist, you could even reveal at some point that there really wasn't any supernatural intervention, the demons who claimed to do it were just swindlers, and drama ensues! [Answer] If a disease is not contagious, and it's not genetic, there is no vector for transmission for the disease and it will die out. You need at least one of these vectors to be active. Genetically, lycanthropy could exist as a homozygous recessive trait that will only show up when both parents have one gene for it. Only individuals with two copies of the werewolf gene would exhibit lycanthropy, so the parents would posses the gene, but not be werewolves. A homozygous recessive trait would also mean that any child of two werewolves would always be a werewolf. It's also that it's a more complex genetic disorder, which is triggered by some environmental factor. Lupus is a disease that follows that pattern. As a communicable disease, you can have transmission at a young age, but only in low numbers, or have a disease that's generally asymptomatic in the population, but which everyone, or almost everyone, has. Of course, there's also no real-world mechanism for making someone undergo significant physiological change under a full moon or become nearly invincible, so you might need to use at least a little bit of magic to actually make werewolves work. [Answer] I'm thinking of MS. They still don't know what causes it. It affects one in every 800 in the UK, something like. All they know is, there is a genetic part - siblings tend to get it too, but children of sufferers are less likely to have it than siblings (I suppose they have less DNA in common than siblings). People with Scottish - Nordic ancestry are more prone to getting it. Some people claim it is triggered by a childhood disease such as mumps, or a vaccine, or some environmental substance. Nobody knows, though many people are working on it. BUT here's the weird part. If people from the same genetic group are brought up in a warmer place, nearer the equator, until they are about 13 (so, puberty), they are less likely to get it. No-one knows why. Here's a link <http://en.wikipedia.org/wiki/Multiple_sclerosis> [Answer] I think the 10% figure would not be stable over time or location. If alleals give resistance to one thing but cause problems, the population will strike a ballance that will shift with the balancing factors. Age onset: I know that puberty is easier, but let me point out that many mental illnesses start showing at early 20's. A friend of mine from high school developed bipolarism after leaving for college; the Beautiful Mind movie showed his schizophrenia upon arriving at university. Something like that (psychological effects) could also trigger linked physical effects caused by hormones controlled by the brain, as with flight-or-fight response. ]
[Question] [ I know wheels have been a pivotal part of every invention and machinery for hunmankind. But currently I'm making an alien civilization with access to floating rocks due to superconductivity. Thanks to floating rocks they manage to skip the wheels period in their civilization. Some of their sophisticated machinery uses joints and sockets. [Answer] Yes... but really, no A "machine" is specifically a compound object that performs more than a simple task. A hammer is not a "machine" (the hand tool, this will make sense in a moment). While it's theoretically possible that "a" machine could be created that doesn't use the basic principal of a wheel, the truth is that I can't think of one. Consider, for example, [medieval industrial mills](https://brill.com/display/book/9789047417224/B9789047417224_s013.xml). A single mill may have one or more of a trip hammer, saw, milling stone, etc. All of these things were driven by a water wheel.... Of course, that same idea is required for rolling pins (making bread), was used for an [early newspaper](https://www.si.edu/newsdesk/releases/2600-years-world-history-one-iconic-object) (a very clever way of shipping many copies of an object in an era when printed paper was iffy), and rings for your fingers. The truth is, the concept of a wheel (aka, a circle or cylinder), while likely discovered before all of the things I've mentioned, is actually at the core of a lot of basic tools, utensils, and jewelry. Now, you haven't explained much in the way of details about your floating rocks, but based on what you have said, they're good for one thing: levitating something. You can't use them to power (e.g.) your medieval industrial mill. In fact, you can't use them to replace pulleys or to build something that's otherwise linear (like a trebuchet) because even these need something to rotate around. Maybe... maybe... you could invent a catapult before you invent the concept of a circular cylindrical thingie (although even those need a rotation point). Maybe a crossbow or ballistia... (dang... both need a trigger, which means a nail, which means a circle or cylinder thingie), but it's far more likely that the idea will come up much, much earlier than that. In other words... Your people will invent cartage before they invent the wheel. But not much else. The tack for the critters pulling the carts floating on the rocks will likely need wheelish objects. Like bits for their mouths. It's a lot more difficult than it sounds to avoid the creation of the wheel when you need so many things in the shape of a cylinder anyway (and a wheel is just a thin cylinder). HOWEVER Does any of what I just said matter? Go forth, write your uber-cool story, and don't worry about whether or not your aliens could invent a machine before inventing the wheel. On Earth, it's difficult to believe... but that's just us and it's really hard to look at our history and see another way it could have happened (and believe you me, we've tried on this site). My point is, your aliens are what you want them to be. Flip us all the proverbial vulgar hand gesture and make it so! Your aliens are not obligated to Earth's history. On your world, those first horse bits were made out of rectangles of wood or metal. [Answer] # Do not use the wheel ### Frame challenge We have some large American cultures in ancient times not use wheels at all. They did have them on toys, so they were definitely known. This opens up the possibility to a culture that knows about wheels, but for whatever reason does not use it. Some none exclusive reasons why it can be so: * The full use of wheels might not be realised. * They value the labour without wheeled contraptions higher. * Wheels used to be a liability in their culture because of terrain. When it was ingrained in their culture they simply did not start using it at a later time when it would be valuable. * It goes against their religion. * Slave labour was seen as better. * They soon have an alternative for wheels, like floating rocks over superconductivity. [Answer] Yes, because that's what has happened historically. A machine is "a physical system using power to apply forces and control movement to perform an action". This includes the six so-called [simple machines](https://en.wikipedia.org/wiki/Simple_machine): a lever, a wheel and axle, a pulley, an inclined plane, a wedge, and a screw. The pre-contact American civilisations didn't even know all of these (they were missing the wheel and axle, obviously due to missing the wheel), which didn't stop them from being, well, civilisations. And strictly speaking, you don't even need civilisation as such to create some machines. A wedge for example (in the form of an axe) predates not only all civilisations, but also anatomically modern humans. [Answer] # Yes, but you'll need to skip some steps Simple machines are one thing, but to get advanced civilization you have to get creative with energy transfer. The ability to float doesn't entirely replace the need for a wheel-like contraption, because you need a source of propulsion as well. Historically, our technology has relied extensively on axle-and-wheel setups to transfer energy from one place (for example, a donkey or a nuclear reactor) to another place (for example, a millstone or an electromagnetic turbine). But we can envision modern technology that does not require the use of wheels at all. For example, while almost every kind of internal combustion engine turns either a wheel (in the case of cars) or a turbine (in the case of jets), solid-state rockets are basically a giant fire pointed in one direction. Similarly, sailing does not require any kind of wheel (although large ships with rigging under high tension may need pulleys). Similarly, while early storage media such as data tapes, CDs, or hard drives require a spinning component, modern computers don't rely on spinning - not even on fans for cooling. As long as you don't have to justify how they got to a certain point, you can envision a machine equivalent of pretty much anything that doesn't use wheels. To make their tech feel different (rather than just asking the reader to take your word for it), you can emphasize that while our wheel-based technology leverages continuous rotational motion to transfer energy, their tech prefers abrupt, linear motion (such as short-firing rockets, gunpowder projectiles, mass drivers, tension stored in bendable or stretchable materials, etc). [Answer] Aim for exotic. If your aliens think in an alien manner, it would be logical that their machinery is alien to humans. One thing that might help is that a side-effect of floating rocks makes the ground mountainous and muddy. Wheels are overrated as a means of transport because people do not consider how much good roads are necessary. Many cultures with the wheel would pack the stuff on mule back even though mules can pull a lot more than they can carry with good roads. [Answer] There is a belief that [mesoamerican civilisations did not use the wheel]. I find it hard to believe that the people who built Tenochtitlan and moved stones that weighed over 10 tons did not use wheels. It seems reasonable that the people who retreated to the cloud cities after the Spanish invasion may have had less use for the wheel. They may not have had draught animals. They used rope bridges to cross chasms. They used runners to take messages. If you lived in Machu Picchu, you wouldn't want a bicycle. I would be surprised if they did not have a wheelbarrow somewhere, but it may not have been interesting enough to put into a picture for posterity. FWIW, whether they had wheels or not, they are an example of a civilisation that left no evidence for using the wheel. People who live in permanent snow and ice do not use the wheel either. It is easier to make a sled. So, that's two. I don't know what you expect of the people in your story. If they have a better alternative to a wheel, then they might use that. But I doubt if they would be amazed at a wheel if they saw one. [Answer] # Yes, they build automatons Consider this: a human has no wheels or wheel-like things inside its body. However, with some simple tools and a lot of effort we can make all sorts of things. So what if they made synthetic muscles, hearts, veins, nerves, and so on, and then built a humanoid machine out of that? That machine would have no wheels (it works just like humans), and it could do lots of different things (like humans). Of course, it doesn't immediately have to be as sophisticated as a humanoid robot, there will already be practical applications for just a synthetic muscle that can be made to contract and expand repeatedly, but it's to show what is possible. Development of this would also take a very long time, just like it took a long time to go from the wheel itself to the car for example. And you would not have the benefit of a wheel in the intermediate stages, which is not only helpful for transportation, but has lots of practical uses. For this to work, the floating rocks must be so useful that you can bypass the whole wheel stage. Maybe the strength of flotation can be precisely controlled, so it can be used to move things (not only vertically), mill, saw and so on? [Answer] ## Depends on the machinery For example computers might be able to be developed without wheels and directly jumping to albeit larger transistors. However physical/mechanical machinery could be difficult. The (gear)wheel has the neat property of being able to take, store and transfer kinetic energy without having to move from its position (relative to the machinery). I think at a certain point they would develop the wheel, especially the gearwheel, because it solves a lot of problems. However what could be possible is that they never came to the idea of using wheels for moving around, since floating rocks are much more convenient for that. Wheels would only see usage in form of gearwheels and the like and not as "roadwheels". [Answer] I'm gonna nope this. When you say "without the wheel," what I hear is "without cyclic behavior." A wheel is a device that deals with everything equally. Using it for conveyance is useful because it keeps everything a fixed distance from the axle. This is the same characteristic that makes it useful as a gear, or a rolling pin, or the axle itself. Since the essence of a machine is the ability to perform a behavior multiple times, in the same manner, I'm going to say that it is impossible to do that without some mechanism that constrains the machine to that cyclic behavior. Thus, no wheels means no machines. [Answer] # Aquatic Aliens Without an immediately available friction surface on which to apply force, the wheel would have significantly less utility in the early tech tree of a civilization of undersea (or possibly airborne) creatures. Apart from gears, pulleys, and such, the basic wheel could actually be almost useless to them. [Answer] # Yes, easily and believably (this is my first long answer, please feel free to fix any formatting issues.) Several answers are trying to explain how repetitive actions and power generation require rotary motion in some form. No, they really don't, springs are sufficient at all stages of development. Pivots or ball and socket joints will help, and I'll point them out, but they aren't necessary. Same with floating rocks and ambient temperature superconductors. ## Early Machines Their earliest hand-operated machines are comparable to the [shadoof](https://en.wikipedia.org/wiki/Shadoof), an ancient water pump which partially automates repetitively lifting buckets of water. The common design uses a counterweighted pole pivoting in some fixed frame, the operator sustains an oscillation between kinetic energy in the moving pole and gravitational energy in the counterweight. For the anti-rotation purists, there's a variation which stores the energy elastically instead of gravitationally by using a flexible pole, rigidly attached to the frame. Some shadoofs have the operator manually tilt the bucket every cycle to empty it, but your aliens will automate this by bumping the bucket against the lip of the outlet chute to tilt the bucket. Trip hammers and other cyclic linear machines are functionally a shadoof in reverse. Water fills a bucket, bending a springy pole until the bucket descends past a supporting lip. With that support removed the bucket suddenly tips, the springy pole jerks upwards and the cycle repeats. This is their equivalent to our water mills, but no wheels, pulleys, or pivots, just automated up-down motion. Transforming that motion into more complicated looping paths is possible, but isn't the highest priority. These cyclic linear machines are enough to start their early industry, operating bellows to heat furnaces, well and mine pumps, grain elevators, etc. I'll skip the long process where they develop precision metrology, but screws, cylinders, and rotary motion (though helpful) aren't required to design or manufacture optically flat surfaces, matched parallel-sided gauge blocks, and comparators to enable precisely shaped components for complex machines. All these parts are mostly hand-finished at this stage. ## Automation Complex sequences of actions are possible without any rotary motion. Ancient and modern irrigation systems use sliding gates to control water, and ancient water clock mechanisms demonstrate the existence of a logical path from manual gates through to complicated weighted, floated, or sprung gates where a small trickle of water can automatically control large flows, even if surviving examples had wheels. Modern car automatic transmissions frequently use hydraulic logic to quickly, smoothly, and reliably switch between different clutch combinations, though they often use a (shudder) rotary pump to create flow. They develop steam engines, pneumatic, and hydraulic tools that use linear motion and slide valves, with overall designs comparable to our earliest [steam pumps](https://www.egr.msu.edu/%7Elira/supp/steam/savery.htm) and [pneumatic jackhammers](https://archive.org/details/mechanicsmagazi03robegoog/page/202/mode/2up?view=theater). The reciprocating linear motion of these components conveniently matches all their established reversed-shadoof linear infrastructure. Their progress is slightly more difficult because we used rotary lathes and cylindrical grinding equipment to manufacture close-fitting components. Shapes with flat sides meeting with either sharp or consistently curved corners are harder to make and harder to seal, they'll use shapers to generate rough flats ([video](https://www.youtube.com/watch?v=tN6ODZZJNkQ)), then grind and lap them to suitable flatness and precision in the same way we produce surface plates and optical flats. Drilled holes will be replaced by stamping and punching, both linear operations. Assemblies would use nails and rivets, with wedges and linear ratchets for adjustment. Avoiding rotary saws and rolling mills would increase costs, but reciprocating alternatives will work. With access to linear steam engines and potentially internal combustion engines, they start working on compound motion and mobile machines. If you bring in pivots and ball joints you can have walking earthmoving and construction machines, but [caterpillars](https://www.youtube.com/watch?v=kbFMkXTMucA) and [cephalopods](https://www.youtube.com/watch?v=-KS-yI8VTf0) are the existence proof that flexible joints are sufficient. The Steam Caterpillar can move smoothly with two pistons per [bimorph flexure leg](https://en.wikipedia.org/wiki/Bimorph), using a simple sequencing valve to coordinate all the legs. Optional steering could use added pistons to slightly bend the body like a live caterpillar, or run all the left legs on one sequencer, right legs on another, and adjust the relative speed like our tracked vehicles. A single ball joint or pivot per leg would help, but multiple joints in each leg just add more and more complexity to controlling and balancing the machine. Sailboats work, as do springy oscillating fans, fins, and sea-snakes. ## Electricity They can use electricity, first with solenoids, then voice coils and reciprocating linear induction motors, using these to drive accurate machines or power linear compressors. In the real world oscillating linear motors are used for some small pumps where their increased noise and vibration don't matter. Their humming noise and vibrations are familiar to users of most aquarium air pumps, and speakers where generating noise is the design objective. Parts of Non-oscillating linear motors must extend along the entire length of their travel path, limiting them to pre-planned routes. Not having access to turbines will increase the cost of electricity, but you can still have planes with oscillating flapping wings powered by linear combustion engines, or pulse-jet and pulse-detonation engines, plus ramjets if you can get fast enough. Several steps of modern semiconductor manufacturing require high vacuum, usually achieved with turbomolecular vacuum pumps. Banning rotary motion would require changing to oil diffusion pumps, but with that exception most of the machines would work similarly. ## Final thoughts Throughout this I've tried to avoid using the word [flexure](https://en.wikipedia.org/wiki/Flexure), which is the proper engineering term for most of these flexible joints. They're everywhere in nature and the built environment, from car leaf springs to inside the tiny pushbuttons on appliances. Compared to regular pinned joints, they don't require greasing to prevent wear or exclude contaminants, but they usually have a preferred position, limited range of motion, and limited load-bearing capacity. All this reciprocating motion is going to create more noise and vibration. I hope they don't have sensitive hearing. My imaginary justification for not wanting circular objects and pivots is simple, their primitive society has survived centuries of political instability. Their leaders were constantly overthrown by coups and civil wars, until any associates of troublemakers were severely punished. Cylinders, cones, and spheres can roll, therefore they're forbidden for their revolutionary tendencies. [Answer] The Inca civilization never developed the wheel beyond use for children's toys despite being one of the most advanced civilizations in the Americas and included innovations such as roads, advanced engineering and mathmatics, terraced farming (the cultivated crops in mountains that are harsh to farming even in the modern day.). As was fitting a civilization that lived in a mountainous region of the world (The Andes are especially difficult to navigate to this day) having carts would be a problem as they would tend to roll down hill and off cliffs. The Inca instead used Llamas as pack animals that they would lead on journeys along the roads from city to city. There is also some debate as to whether the Inca could have stood better against the Spanish had they not have had the misfortune of being in a succession war at the time of first contact. The famous Inca Roads were not ideal for the Spanish to travel (the reason for this is, because of a lack of use of wheeled carts, these roads were made with steps for the inclines, which the Spanish horses hated, making travel difficult to say nothing of supplies that had to be pulled by draft horses.). [Answer] It's important to understand that the wheel is pretty useful because it can spin forever (assuming you can reasonably apply force) and thus apply unbounded quantity motion to a system. I'm not certain that floating rocks could fulfill that need -- if you think about it, what is a floating rock? It's a rock that travels in on direction. We already have that in the form of regular rocks -- they also travel in one direction. The key difference is you have opposition -- this could be a great energy source I'm certain, but if left to their own devices the rocks are just going to travel to their lowest energy state (regular rocks to the ground, floating rocks to whatever height the magnetic field strength is equal to the force of gravity). Without a wheel, or some other means, you have no way to reset the floating rocks to a state that allows for more energy to continue to flow, so no work can be done with them. If you had say a single point where rocks converged to went up and then went back down (like a geyzer), you could use this energy to power something, but probably the best solution here would be a floating-rock coughwatercough wheel. Floating rocks would certainly be useful in a lot of scenarios, but I'm not certain that a civilization could grow and thrive beyond say our medievil era without a wheel. The industrial revolution would be very difficult, more difficult for us and it only took - 150 years to happen. [Answer] Do not use sockets - sockets are the slippery slope (hah!) towards wheels. You did not specify how those floating rocks of yours work, but i am just going to assume they can be harnessed as a mobility platform, thereby nixing one of the first needs for 'wheels' (I am going to use 'wheels for anything that rotates without movement in axial direction (so screws would not count as wheels, treetrunks rolling below a stone slab would). We had bamboo and circular-crossection wood that gave us a first leg-up in the technology game - find a nice specimen and you have a ready-made perfect axle without any hassle - use it for transportation, as a fulcrum for a lever, as an axle in a waterwheel. You rely ever-more on it's use, and soon arrive at the need to manufacture them - metal or stone both do not naturally form into round cross-sections, but you look at the 'prototypes' and know which way to go. But what if we did not have that? If all your plants materials have a triangular, quadratic, or irregular crossection? No animal bones with circular crossection, no mineral deposits in that shape, nada. - This would push back the invention of the wheel, but we need to offer alternatives, to really make this work - what if your world, besides floating stones, also has a plethora of really good bendable proto joints? - i mean, we seem to have that too, with bamboo and leather, etc., but we need more of this, and a real ecosystem around it: many naturally-flat surfaces, good adhesives, material with many slots, ... all this in the absence of anything circular, and you have the beginnings of a civilization based on bendable-joints. You also need very good lubricants to not stymie the development of rope-based mechanisms, as they need minimal friction on the deflection points, otherwise they are not viable. * [Flapping windmill](https://www.zmescience.com/ecology/renewable-energy-ecology/flapping-turbine-hummingbird/) (And in extension, water wheel) * [walking-type transportation](https://1299651405.com/strandbeest/) (Think Strandbeest, but without axles) Basically you would abolish the idea of 360° rotations, and base your technology on reciprocating, oscillating, and flipping. I realize that circular crossections have another very nice characteristic: they make the ideal pressure vessels, so water pipes will need to be circular to be used in anything requiring even moderate pressures - though if nature provides good adhesives, ropes, and some nicely straight, quadrilateral-crossectioned (or crosssectionable) planks, the resulting coopered tubes might also serve. Or maybe there is a hollow plant- or animal-based material that has a non-circular crossection, but gets one in response to internal pressure? (Should also give it banana-shape to make extra sure sneaky humans do not find a way to stuff it for axle-use) As soon as you enter the metalworking ages, there will be wheels, but i gather you just want the civilization to start out without ]
[Question] [ In a parallel universe system (previously discussed [here](https://worldbuilding.stackexchange.com/questions/31046/portals-to-parallel-earths-economic-effects) and [here](https://worldbuilding.stackexchange.com/questions/152275/parallel-universe-portals-an-infinite-hall-of-mirrors)), portals are mechanical door frames that, when activated, cause a copy of your universe to appear on the other side. You and your parallel-universe doppelganger initially mirror each other's actions, but after some small amount of time, due to quantum fluctuations (don't worry about it), the two universes de-sync. After that point, there's just two of every object, but the two universes can evolve in different trajectories. The question is: what's the best-possible naming scheme for these parallel universes? Traditionally in stories with multiple universes, this is not explained ("I'm from Earth 187"). However, simply calling the Nth universe we come across "Earth N" isn't going to work in this case. Here's why. Every time you make a portal, you not only duplicate the current universe, but all other existing universes. After all, if you have a portal you set up last week in your basement (let's say, to an "Earth 2"), and you open a new portal in your attic to an Earth 3, then of course your house in Earth 3 has a basement with a portal in there that leads to an Earth 4. Note that this 4th universe doesn't have a portal in their attic, because you set the attic portal up after the basement portal de-synced. (Please, please don't argue in your answer that the portals don't actually work this way. This is easy to misunderstand, so if you think every portal needs to connect to the same universe, or it goes on infinitely, or some other reason why the whole premise is flawed, just don't write an answer. It's not helpful.) In summary, every time any portal turns on, the number of universes doubles. I considered giving every universe an ID, and then when a new portal opens, adding a 0 to the end of every ID on one side of the portal and a 1 to the end of every ID on the other side. However, an ID with a number of digits equal to the number of portals is way too long and cumbersome to use in day-to-day life. And if you shorten it by converting from binary to decimal, then every time someone opens a portal, everyone in every universe has to memorize a completely new set of digits. Note that the arrangement of portals isn't always a straight line, either, so numbering them from 1 to 2^N is out. For instance, you could open a third portal in your living room to Earths 5 through 8. Now Earth 1 connects directly to Earth 2, Earth 3, and Earth 5, while all other universes are more than one portal away from Earth 1. An ideal naming system would give connected worlds similar names. To summarize, a perfect naming system would be * Robust (every universe's name should not change drastically when a new portal opens) * Concise (I won't give a character limit, since maybe keywords work better or something, but it needs to be memorizable when there are, say, 20 open portals, or roughly a million total worlds) * Local (every universe's name should be similar to the names of the other universes that it's connected to). A fully-perfect solution probably doesn't exist, and it's easy to come up with solutions that do extremely well on 1 out of the above 3 criteria. What I really want is a naming convention that does pretty well on all 3 counts. [Answer] 23:12:24:78:123 Refers to the world you get when you start from your current world via gate 23, leave there via gate 12 and so on. Numbers are simply world unique gate identifiers. It does not really matter what they are based on as long as the identifier clearly refers to a specific gate within the world it is used in. The example would probably be based on order of creation but identifiers based on location, time of creation, or anything work just as well. But they must be permanent. You assign the identifier before you open the gate and never change it. This way all gates have the same identifier regardless of direction. So if you have travelled to 23:12:24:78:123, your original world will be uniquely identified and reached by path 123:78:24:12:23. And if inhabitants of 23:12:24:78:123 tell you about the wonders of world alpha:calcutta:7, you can after returning home identify just append the path to 23:12:24:78:123:alpha:calcutta:7. Which is convenient. You can also do other operations with names. The name of world 23:12 in world 23:12:4:8 would be 8:4. World 23:12:8 would be 8:4:8. This naming is robust. Opening new portals has no effect of previous paths. Opening portal 24 just means that you can now go to world 24:23:12:24:78:123 that starts very similar to 23:12:24:78:123. System is concise. Since the path is minimal information needed and each gate needs to be uniquely identified, this is the most concise possible system. System is as local as possible. Worlds directly connected vary by single identifier. Worlds connected to current one have single identifier. Worlds connected to world 23:12 are 23 and 23:12:\. [EDIT](https://worldbuilding.stackexchange.com/questions/169491/naming-parallel-universes/169590?noredirect=1#comment530558_169590): The system can be adjusted for moving gates thru other gates. While you cannot ever change names without breaking the system, you can* extend them. The extension needed is simply the path the gate travelled. Since such paths are unique under this system, the only problem is detecting stale paths using the old name which must be updated with the new name. Upstream stale paths can be recognized because they leave the origin system thru a gate that is no longer there. People in the origin system simply must record the the old and new name and tell travelers to update their path correctly. Downstream stale paths can be recognized because they arrive from the new gate using the stale name. So they can also be easily updated. This can be automated and be done by computers integrated into the gates communicating with equipment all travellers are required to carry using standardized protocols set before the first gate was opened. [EDIT2](https://worldbuilding.stackexchange.com/questions/169491/naming-parallel-universes/169590?noredirect=1#comment530662_169590): A comment by Justin Thyme the Second made clear that such automated information system is necessary even if gates cannot be moved thru other gates. Since all the names are only locally valid they must be updated to reflect the path they travel to remain valid. While this is trivially simple to do, you do not want to rely on people remembering to do it. [Answer] You do realize your mathematical problem here, yes? Start with one universe and 1 portal. It gets turned on, two universes, both with portals. You turn on your portal again. Four universes, all with portals. One of them activates. Eight universes. Two of them are turned on one right after the other. Thirty-two universes. Three of them turn on portals. Now 256 universes, all with portals. Ten portals get turned on the next day: 662,144 universes. The next day is a quiet one; only 50 of those universes turn on their portals. You're now at 2.9514 x 1020 universes. How many of them decide to turn on their portals? It doesn't matter what kind of numbering or naming system you chose; you'll very quickly realize you've run out of any kind of practical method. ADDENDUM Additional problem: how can you know what name your universe is? If opening a portal causes all the universes as they currently exist to duplicate exactly, then how do the "new" universes know they're new, especially if they're created as a result of someone else triggering a portal in a universe no longer connected to yours? ADDENDUM ADDENDUM In response to the suggestions about naming schemes: Just for giggles, let's suppose of those 2.9514e20 universes I mentioned previously, 100 activate portals. Now we're at 3.74e50 universes. Another 100 activate: 4.74e80 universes that require unique names. Now, bit of a problem: there's only an estimated 1080 atoms in the universe. Now keep going on this process. There will come a point where the information required to store the universe's name will exceed the information available in the universe. Probably a lot sooner than you think. How much of your universe are you dedicating to just keeping the name written down somewhere? Let's suppose it takes a nanosecond to update record name in a universe and transmit that information on to the connected universe(s) so it knows to update its name as well and pass it on. And, to play fair, we'll only consider the 2.9514e20 universes, so all of them have free atoms to actually build a computer and have memory and such. It will take about 9,359 years for information to propagate through the existing network. Which, of course, will soon reach the heat death of the universe to let everyone one that another portal opened somewhere and the name changed. Again. And doesn't take into account any time needed for coin flips. And that's passing information from one universe to another in a nanosecond. A time span in which light will move in a vacuum about 30 centimeters. ADDEN...whatever The name change thing is going to create a problem on its own. Once any universe opens a portal, information has to be sent to other universes to update designations. Now imagine a situation where in any given second, there's a 1 in a trillion chance any given universe will open a portal. Which is, obviously, a very small chance. With 3e20 universes, that means that in any given second there will be on average 300 million portals opened. And you're going to get the announcement your name has changed. Three hundred million times. Per second. Now imagine what's happening the next second. [Answer] I'm putting this up as a response/solution to Keith Morrison's answer. In short: you're kind of done for. Numbering anything, whether it is parallel universes or fruits in grocery stores, is complicated once you have enough of them. What's the difference between one apple and another apple? What makes an apple Apple 1 vs Apple 2? Also, even if there are a finite/countable number of apples, how countable is it? My solutions are way more complicated and I'd argue way more subjective. To an extent, I don't even recommend it because numbering might be easier to understand and less likely to garble up. I have two ideas: 1. Nomenclature based on portal creation route: I don't want to get myself bogged down in your portal creation system to other parallel universes (as you said, we shouldn't base our answers on that). But I'd like to provide an example similar to the one you've given. * What if you had 2, 4, 10, or even 1000 portals to different universes in your Earth 1? Let's not even step into Earth 2 or anything - how would you number these? My solution to this problem is to name every universe on the basis of its portal creation. So, your Earth 2 would actually be Earth 1-1, as your first portal in your origin universe leads to it. If you want to get properly computer-science-y about it, maybe a better name would be Earth 0-0. * What about a portal in Earth 2 to Earth 5 (working off of your own example, as Earth 4's portal is in Earth 3)? This universe can be labeled Earth 0-0-0. * What if you want to label the parallel universe that is accessed by the 2nd portal of your 4th portal of the 3rd portal of your origin universe? This universe is therefore Earth 0-2-3-2. If you want to fit more numbers per digit of your parallel universe address/naming system, maybe name all of these universes in hexadecimal (base 16 as opposed to base 10 numbers). Basic structure of name is therefore (in terms of bad [context-free-grammar](https://en.wikipedia.org/wiki/Context-free_grammar)): `E->O O->P P-> int\|O\|P\|Null` This also raises questions like whether portals in different parallel universes lead to the same parallel universe, creating a new mess: The Inter/Intra-relations of Parallel Universes. So, could Earth 0-2-4 be the same as Earth 2-1-9? If so, how do we know that? Does this naming convention help at all? Is it even related to what we're discussing? Or does it just serve to confuse? These are questions you'll have to answer if you pick this option. EDIT1 Coinflip debacle: OP pointed out the coin-flip nature of naming these universes. The only way you can guarantee that this method works is by hoping you win every coin flip, which is what every version of you will attempt to do. So, we have complicated solutions to this as well: Dictionaries: Who cares about coin flips? Every 'you' will think they're from the root universe. Being the headstrong guy you are a coin-flip doesn't define you. So, you and your duplicate can formalize a dictionary for what you consider to be your universe and root universes below it, creating a more complex hierarchy of universes that will lead to a self-propagating accumulation of ego. This will only make itself more complicated for more and more universes created. The dictionary part of this comes into play because your Earth 0-0 is someone else's Earth 0-2-5, so you'll need to make a pretty comprehensive Excel spreadsheet to document every universe. Finite coin flips: You and all your duplicates stop making portals after some number of iterations. Do your coin-flip war, make a single static definition that everyone will have to deal with. If you were 0-2, now you are 0-2-0-0, and you'll have to deal with it until the next update comes out and all the yous can go on a portal spree again, and flip your coins again. That's all I've got so far - will add more ideas if I come up with any. --- 2. Event-based nomenclature: I'd like to point out that I dislike this idea more than the other one. In this case, you're labeling each universe on the basis of important universe-defining events that happened here that differentiate it from others. Earth 1 and 2 might be very similar universes (same laws of nature, positioning of stars, etc.) but maybe computers aren't programmed in binary in that Earth 2 - but in every other sense the computers work the same way (accessing Facebook is the same in both these universes). Or, maybe in Earth 3 the French Revolution didn't succeed, leading to a vastly different political atmosphere in their present day, but computers are still binary. Depending on what differences exist in these universes, you can make a naming convention that suits it. So, if we only take these 2 events as defining factors in a universe, then Earth 1 could be Earth 00, with Earth 2 being Earth 01, and Earth 3 being Earth 10, raising the possibility of an Earth 11 (where the French revolution failed and computers don't use binary). Unlike the previous point, this example is more absolute and less 'relative'. If the order of portal creation doesn't determine which universe you go to (i.e. you can make >1 portals to the same destination universe from the same origin universe) then this is a great naming convention. Only issue: What are the defining factors of a universe? A countless number of events happen every day on our planet, let alone others, and there could very well be universes where Earth doesn't exist at all. So how do we know that the use of binary and the French Revolution succeeding/failing are important enough to define a universe? Realistically we don't, but you write your own story so you can choose. I hope my solutions were not too verbose - I'm open to any questions/clarifications. The biggest differences between the 2 solutions I provided is that option 1 is potentially relative with respect to other universes, whereas option 2 is a more absolute definition but how the definition is constructed is incredibly complex. I hope this helps! [Answer] If these universes exist in an n-dimensional space such that some parallel universes are "closer" than others (either requiring extra power to the portals to go to more distant ones or to traverse intermediate universes first)... Then the best namespace design is a coordinate system. This will work up to the double digits for the number of dimensions (note that I don't mean "dimensions" as in xyz+space here, just the number of different factors that describe one universe's adjancency to another). You won't be able to hash these universes coordinates to come up with a more human-readable name either (since hashes can't be reversed to the original coordinaes). If the extent of any single dimension is low, then something like a "guid" might be possible to make it smaller, either using hex or some other number base. So it's possible a name will consist of a long paragraph of comma-separated numbers. If there is no dimensionality (all universes are directly reachable from all other universes), then there is no reasonable namespace convention possible. If on the other hand, each portal retains it's connection, then you don't need a namespace, you need a map. And it's unclear that it would have to become complicated... human-meaningful names would be chosen for each portal by consensus among the two universes relevant to that portal. And governments would likely crack down on the creation of new portals, it would become strictly regulated. Idiots would be opening new portals to try to get back together with a girlfriend whose original had already broken up with them (even though the doppelganger would be exactly the same for our purposes). People would be trying to get away with murder (and abducting doppelgangers to prove they were still alive). Etc. So I expect the map would remain rather small, with portals numbering in the thousands or tens of thousands at most. [Answer] The growth is exponential, so any naming convention would need to match that exponential growth. Therefore, I propose the following binary structure for names: * The initial Earth is Earth Prime. * The first duplicate is Earth Null. * The second duplication will be counted in Binary - Earth 0 and Earth 1. * Every subsequent duplication is then given an additional value slot. For instance, the third duplication of the Earths will be given a two-digit moniker - Earth 00, Earth 01, Earth 10, and Earth 11 respectively. The fourth duplication will have eight designations - 000, 001, 010, 011, 100, 101, 110, and 111. * When world are duplicated, the new world arranged numerically, earlier duplicate sets first. In other words, in a fourth duplication, the 000 position is occupied by the replicated Earth Prime, 001 by Earth Null, 010 by 0, 011 by 1, 100 by 00, 101 by 01, 110 by 10, and 111 by 11. Thus, in order to figure out what duplication set you are in, you check the number of digits and add one. An Earth with a 40-digit binary code, for instance, will be part of the 41st duplication. Then, you use the binary code itself to figure out what world number you are along that line. Simple, concise, and information dense. (Save for the first two Earth, which must be given special conditions as they don't fit the pattern.) [Answer] ## Strictly local names. As pointed out in [Keith Morrison's answer](https://worldbuilding.stackexchange.com/a/169494/10324), trying to give everybody globally unique names is not going to work. At all. [Justin Thyme the Second's answer](https://worldbuilding.stackexchange.com/a/169547/10324) points out that most people will consider themselves to be from Earth. The original. Taken together I think that every Earth will name itself "here". So you are "Gilal M from here". Most people will stay at home. After traveling through a portal you will gain a modifier to your name like "Gilal M from beyond the Google Portal." Traveling further you become "Gilal M from beyond the MSN then Google Portals." Some sort of abbreviation will be needed for far away travelers. If you go back through the same portals you will lose modifiers until you reach your home again. Portal names will only need to be unique for one given Earth. I would like to expand on Keith Morrison's example to show how hopeless the situation really is. In my example there is only two portals, or so it seems. Google and MSN are competing to build the first portal. Google wins, but MSN is only a day behind. On Monday the world splits into Earth-1 and Earth-2. So far, so good. On both of these worlds, MSN is going to open another portal. Two worlds with pending portals. Due to random events, MSN on Earth-1 arrives first, but Earth-2 is only an hour or so behind. On Tuesday, at 9:00am, Earth-1 splits into Earth-1A and Earth-1B. Earth-2 splits into Earth-2A and Earth-2B. On both of these worlds, MSN is going to open another portal. Two worlds with pending portals. Due to random events, MSN on Earth-2A arrives first, but Earth-2B is only a few minutes behind. On Tuesday, at 10:00am, Earth-2A splits into Earth-2A1 and Earth-2A2. Everybody else splits too. On both of Earth-2B1 and Earth-2B2, MSN is going to open another portal. Two worlds with pending portals. Due to random events, MSN on Earth-2B1 arrives first, but Earth-2B2 is only a few seconds behind. On Tuesday, at 10:10:00am, everybody splits again. On Tuesday, at 10:10:10am, everybody splits again. On Tuesday, at 10:10:10.1am, everybody splits again. After this trilling game of Zeno's World Splitting, there is an infinite number of worlds. And the week has just started. If this is hard to accept, consider the following scenario. As above, Google and MSN has built portals on every world. What happens if you first go through the Google portal, then the MSN portal, then the Google portal of that world, then MSN, etc Will you ever get home? The answer must clearly be no. You cannot get home without retracing your steps, and you never do. So, you have an infinite number of worlds to visit. Have fun naming them. [Answer] Is there a direct need for a naming convention? It only really makes sense for an outsider, someone who isnt even connected to any of these universes. When you create the first portal and new universe it is perfectly identical, and from inside the universe there is no way of telling which one is the "prime" universe. Then if you create a new portal you encounter this problem again. Even if you create infinite new universes this way each universe can trace a history back to it creating the first portal, and can therefore assume it is the prime universe. So instead of trying to name each universe they just communicate with each other. For example they say "I'm connected to 10 universes, and you are connected to 5 universes. We buy some D&D dice, throw them until a number comes up that isnt present in any of our cumulative 15 connected universes and accept that for our universe name". The number of dice coukd rely on the number of cumulative connected universes. Yes maybe 2 connections down the line there is a universe with the same number, but that doesnt matter much for most travel between the universes you are in. [Answer] Robert Heinlein dealt with this when crafting the Future History series of books. He solved the problem by assigning each universe a name and a number. He recognized that most changes we deal with are quickly diluted with the randomness of everyday life and not recognized as unique. If the electron in the tip of my finger is spin up in one world and spin down in another, the two are really indistinguishable for all intents and purposes. There's no meaningful way to assign names to worlds whose differences cannot be measured. Instead, he argued that most important changes occurred at "cusp events." These were events of great importance that shaped the course of humanity. One of those cusp events was who landed on the mooon first. Thus we might be from timeline "Neil Armstrong 67." This let us distinguish individual timelines quickly by cusp events, and then delve into the details of the timeline by number later. While you still have to number all your universe, a similar pattern might work: a short synopsis followed by a number. You probably want a coded number like an IPv6 address to track enough details. Our timeline might be `Gutenberg, Einstein, Hitler, Neil Armstrong, Oprah Winfrey 2001:0db8:85a3:0000:0000:8a2e:0370:7334` [Answer] # You don't need to name them all Keith Morrison has already explained the impossibility of naming them all, the argument I'm going to make is that you don't need to. There's no possible set of circumstances under which you need to identify an arbitrary universe in your set. You only need to identify an universe you can reasonably interact with. The only way to interact with another universe is to pass through a portal to get there. Which means you can address any universe by the path you need to follow to access it. If you encounter another traveller in a distance universe, you can reverse their path to locate their universe relative to yours. No name is absolute, everything is relative. [Answer] As long as the two universes are largely the same, you don’t need to differentiate them. You can interact with either interchangeably. What matters is once they start to diverge. So name them based on the first notable divergence you notice: Earth Mom-said-no, Earth the-dog-barked-twice,etc. Over time you may rename some based on more significant divergence. The naming is relative to the person who opens the portal, anyway, so why not embrace that subjective focus in the naming? [Answer] Looking at all the previous answers it seems clear that you can only achieve the things you require, instant naming and single individual IDs (no accessing my facebook or bank account) if you invent a new measurable universal property that is unique to each universe. Using my hand-held and waveable quantum signature gizmo I can measure each universes paralleism state. This is a simple [guid](https://www.guidgenerator.com/), that the pocket device turns into a naming phrase, like [what3Words](https://what3words.com/terms/), but auto generated from the GUID rather than relying on a hand cranked list. You're still going to run out, over all your parallel universes quite quickly. But you should have enough locally unique names that your characters can't realistically travel far enough to meet a duplicate name. On duplication, everyone used to live in CorrectHorseBatteryStaple, and now the duplicates live in SpaceBannanaBurningHole. It's annoying that I've become the B universe, but given the quantum signature doesn't change after duplication I've no choice but to believe the device. How you get the two factor authentication to check my quantum signature is a puzzle I leave up to the bank. But obviously they don't have to actually care what the universe's signature is, just that the person accessing as the same one. So the bank's end could be plugged into, say, a small piece of fairy cake. [Answer] I am trying to envision this as a tree diagram. Start at the root, and you have two branches, say Alice and Bob. Alice splits off, goes her own way, and splits into another branch, Alice and Alice-Mary. Bob goes on, and splits into Bob and Bob-John. Alice-Mary splits off, and has a branch Alice-Mary and Alice-Mary-Jane. The original Alice continues on and splits into another branch, Alice and Alice-Susan. Do the people in the universe Alice-Mary-Jane know anything about the people in Alice-Susan? Or even Bob-John? It seems they would have de-synched and lost connectedness. Or can someone in Alice-Mary-Jane go back to Alice-Mary, then Alice, and then forward again through Alice to Alice-Susan? If someone can traverse the tree, in order to make sure no spawned universe gets the name of another universe on a different branch, without knowing it, the solution would seem to be an ever-longer-growing name that always references the route along the tree, unless there is an omnipotent 'master cataloger' who can see the entire tree all the time. If a person could not 'surf the tree', then a duplicate name for two universes on completely different branches would only matter to the omnipotent reader, not to any particular resident of any particular citizen in any universe. To them, they might just as well be called, simply, 'Bob' and 'Alice' and 'Alice-Mary' and 'Mary-Jane'. That is, the name of the spawning world, and the spawned world. Just like married couples today either just take one last name of the other partner, keep their original last name, or take the groom's last name and the bride's last name, not the entire groom's family tree last name, and the bride's family tree last name. Otherwise, when a James-Ming-Nile-Smith married a Mang-Spencer-Wilson-Porter-Sanainil-Popodoupolous, the new child's name would be... I just don't think it would be practical to have any kind of a 'descendant' naming convention, so go with some simple, unique name for each world, and keep track of it with some form of tree diagram in the appendix or the front fly for the omnipotent reader. [Answer] This is answer 2, because the more I think about it, the more I realize that no one in any universe would allow their 'Earth' to change names. Either that, or these inhabitants would not be humans. John Smith, born Jan. 31 2010 in Liverpool, England, Earth would be John Smith, born Jan. 31 in Liverpool, England, Earth after the first clone. Both of them. The parents would be John Smith Sr. and Mary Jones. And the parents would be exactly the same. Indistinguishable. But after the clone, John Smith Jr. marries Henry, but John Smith Jr. marries Henrietta. And John Smith Sr. and Mary Jones break up and divorce. But John Smith Sr. and Mary Jones live happily into their retirement until death. In their minds, in their psyche, they were all born on Earth. Period. And then, another universe is cloned. John Smith Jr. born on Earth (not Earth 1, or Earth001, or whatever, but Earth - that is what his birth certificate and legal documents state, very clearly) now has four clones. Each one born Jan. 31 in Liverpool, England, Earth, with John Smith and Mary Jones as parents, born on Earth. Not one of them would change their names, just because anther clone exists with the same name, somewhere else. Every clone is exactly the same person. Same DNA. Not one of them is going to change their names. These are the names they were born with, and have a right to. So which one is going to allow their history to be re-written? The place of birth, the name of the place where they were born, doesn't change. It is and always will be Earth. Unless you re-write every clone universe history. Everything in the past stays the same, no matter how the future changes. What has happened, has happened. The Earth is named Earth, and it will not change. Are (were) the deceased grand-parents thus clones? Or are they the same person? The clones didn't exist until AFTER the earths are cloned. How can dead and fully decomposed people thus end up cloned? They didn't exist before. Or does cloning a universe clone everything that happened in the past? What would that even mean? Would a clone from one earth, traveling through the portal, consider their parents on 'the other side' still as their parents? After all, their DNA came from them. They came from the same womb. So how does a person completely change their heritage, when their heritage doesn't really change? They are all descendants of Earth. One Earth. No, I am afraid the Earth would always be called Earth, every one of them. Unless any future inhabitants of one earth decided to call it something else, and then the name would be unique and meaningful to them, unrelated to any arbitrary naming 'convention'. Maybe the inhabitants of one Earth might come up with nicknames for the OTHER Earths, but I guarantee you, if we are talking about humans, they would be derogatory and completely unacceptable to the OTHER Earth's inhabitants. If these are humans, you are stuck with Earth. Every last clone of them. And they would be right. Every instance would be properly called Earth. The naming convention is strictly for the convenience of the omnipotent author and reader, not the inhabitants of the story. There would be no 'coin flipping', no 'lots cast'. It is entirely at the discretion of the author, entirely for the author's own purpose, as the omnipotent overseer, trying to bring order to chaos. [Answer] Lots of people here seem to be overcomplicating it. Use binary fractions as a starting point: * Earth 1 splits into Earth 1.0 and Earth 1.1. * Earth 1.0 splits into Earth 1.00 and Earth 1.01. * Earth 1.1 splits into Earth 1.10 and Earth 1.11. Since the integer part is redundant, we can use it to count the number of otherwise-ambiguous trailing decimals. * Earth 0 -> Earth 1.0 and Earth 1.1 * Earth 1.0 -> Earth 2.00 and Earth 2.01. * Earth 1.1 -> Earth 2.10 and Earth 2.11. Since you said > > Every time you make a portal, you not only duplicate the current universe, but all other existing universes > > > we're doubling the number of universes each time, which basically means adding a digit after the decimal. The observation which simplifies this whole scheme (if you are willing to complicate this particular aspect) is that the name of every universe changes each time there is a split. Luckily this is a change which is entirely predictable and easy to read. Example, Earth 2.10 and Earth 2.11 both used to be called Earth 1.1 at some point in the past. One might argue, philosophically, that Earth 2.10 and Earth 2.11 both always have existed, but before the split happened they were identical and interchangeable. (Arguably, this is what the "many worlds" interpretation of quantum physics is really saying, the universe doesn't "split" when Schoringer's cat either dies or survives, both timelines are eternal and the apparent "split" is just recognising the point at which they start to disagree.) The hard part of your situation is a communications issue: if EVERY world splits when ANYWHERE opens a portal, you need to agree on the ORDER of splits events if everyone is to agree on a naming scheme. [Answer] I would use both IDs and path history. When a portal opens, it automatically assign a random UUID ( <https://en.wikipedia.org/wiki/Universally_unique_identifier> ) to the door. It won't be able to identify every existing door but will at least allow to differentiate the close ones and avoid that multiple active doors have the same name in the same universe. Each universe keeps track of its own open doors and their IDs. Then, when you travel, you keep track of every door you go through. When someone ask you where you come from, you describe the reverse path: * You leave your universe through door X, then go to the next through Y, then Z. When you meet someone in the last universe, you can explain that you are from Z-Y-X. You could also describe your universe by giving all the IDs of the doors open in it: * "I'm from ABQJZ, you know it ?". Of course, in the infinity of universes that will be created, there will be a huge number of universes with "ABQJZ" doors, but what are the odds that they will be close to you ? If the guy just went though 10 portals to get to your universe, chances are the universe ABQJZ saved in your database is the same than his. It's not foolproof but I think it's efficient enough for navigation and keeping tracks of the universes around you. EDIT : Clarification on UUID An UUID actually looks like this : 07d84f17-f0cd-41da-a103-970974a17d11. I've replaced it by a letter in my answer for clarity (but apparently failed !) and space. Someone going though three doors would mark his path as : 07d84f17-f0cd-41da-a103-970974a17d11.de12f6b7-fab9-4021-bcf2-ba6978a4acc0.5a2a53c9-cff6-4c60-846b-f150101a1d78 [Answer] # Terrian, Elevation, Latitude, Longitude I'd recommend the T.E.L.L. (time, elevation, latitude, longitude -- popularized in 'Travellers') of when and where the split from the 'primary' timeline occurred, and an (Left, Right) ordinal indicating which of the several possible simultaneous branches this one is. Because doors duplicate, there are only two : by right-hand rule ('Right' the door knob is on the right, 'Left' on the left) This coordinate is local. So, the next branch would be relative to the new timeline. A fully-qualified world name starts with the earliest time, and continues appending TELL-suffixes up to the most recent leaf. # Shorthand for Convenience For short-hand, the closest city and year works. For example: AthensApril179Right : Byzantium238Left This can be simplified further if only one door was ever opened in Athens. In that case, AthensLeft or AthensRight is sufficient. On the other extreme, if hundreds of doors have been opened in Berlin the name can offer the necessary detail (up to the limits of your ability to know when and where the door opened). Examples : Berlin1931April26-0135, 0136, 0137 -- in that case, it may be easier to shorthand the event everyone is going to : BerlinOlympics-0135 # Simplest Form The shortest version will be the TELL of the most recently opened door in this universe. Since time marches forward, there should always be only one "most recently opened" door. In your example : * 'Earth 1' is BasementJan2020Right, * 'Earth 2' is AtticFeb2020Right, * 'Earth 3' is AtticFeb2020Left, and * 'Earth 4' is BasementJan2020Left (if I have the order right). Alt-names. I think this is your set-up : * E1 : + E1 (also called E2) + E3 * E4 # Uniqueness of Synonyms for the Same World Because of the time and location component, MyHomeTownBasementJan2020Right is pretty unique in all of the multiverse. It doesn't matter that the proper short name, after opening the door in the attic in MyHomeTownAtticFeb2020Right -- both names are highly unlikely to conflict with another in the multiverse. # Disambiguation Let's say that both AtticFebruaryLeft and BasementJanuaryLeft both decide to go to the same neighbor's house and open a door. In the unlikely event that both of these timelines open a door so close to the same location that you can't measure a difference, and so close to the exact same time that you can't measure a difference. Then two completely unrelated sets of NeighborsMarch2020 have been created. It's possible to disambiguate by prefixing the parent world : AtticLeft-NeighborsMarch, or BasementLeft-NeighborsMarch [Answer] Okay, answer number 3. We have been looking at this wrong. It IS indeed a binary tree diagram, but the root is not at the FIRST Earth that existed, The tips of the branches are the Earths, The node just indicates 'another clone occurred'. Start at the beginning, with one earth. Neither 1 nor 0. Just earth, because no other exists. Then another Earth is cloned. So we have Earth 1 and Earth 0. Earth 0 does not exist as Earth 0 until another earth is formed to be Earth 1. Until then, it is just Earth. But the node is NOT at earth 1 OR 0, it is one level above. We have to add a bit to indicate the creation of the portal, the two clones. Earth 0 is now earth 00. The clone is earth 01. The Earths are the TIP of the end branches, the LSB 0 and 1. Two Earths. The address as it were, NOT the node. The node represents that a new portal appeared anywhere on any of the branch tips (or Earths), causing everything to duplicate, not a portal on any particular Earth. That is, it represents the duplication, not the portal. Thus, the added 0 on the most significant bit represents the creation of the portal, the beginning of the added branch between 'old' and 'new'. (For the sake of clarity, I will call them 'old' branches and 'new' branches, even though they could not, in reality, be differentiated into 'old' and 'new'. EITHER could be labeled as a '1' or '0', but thereafter would ALWAYS be a '1' or '0' in the tree as their LSB, odd or even.) A clone happens on EITHER earth, so the tree is duplicated. Now there are four Earths, not two, at the branch tips. That is, there are four branch tips, not two. Two 'old' ones, and two 'new' ones. So now a new branch starts from the top of the tree, not the bottom. And not from the portal on any Earth. The portal and where it exists or what Earth it exists on is irrelevant. What is important is that all of the Earths are cloned into exact duplicates. There are two more Earths, named Earth 0 and Earth 1, identical to the old Earth 0 and Earth 1, but another branch from the node has been created. The 'old' Earths now stay Earth 00 and Earth 01. But the new Earths become Earth 10 and Earth 11. The branch is NOT from the original earth, but from the added branch. The least significant bit of the Earth name does not change. (It doesn't matter where the portal is, or on what Earth the portal is, or how you get from one Earth to another. This is not a road map between Earths through portals, but a tree diagram for a naming convention. Every time you clone, the number of Earths doubles, no matter how you get to them or where they are on the road map.) So another clone happens from anywhere. The existing branches all exist, and the new branch would also be labeled as 00 and 00 and 10 and 11. But now we have to add an additional Most Significant Bit node further out on the existing tree, to indicate the split into old and new. The old Earths would be 00, 01, 10, 11, but now duplicated and renamed into 000, 001, 010, and 011 and the identical new earths would be 100, 101, 110, and 111. Another clone forms, from anywhere, any Earth, on the tips. The new branch does NOT start at that tip, but at the tree root. An entirely new copy of the tree is formed. The eight old Earths are named 000, 001, 010, 000, 100, 101, 110, 111, but now they are divided into old 000, 001, 010, 000 100, 101, 110, 111 and new 000, 001, 010, 000 and 100, 101, 110, 111, so they are named with an additional MSB and are now called 0000, 0001, 0010, 0000, 0100, 0101, 0110, 0111 and new 1000, 1001, 1010, 1000 1100, 1101, 1110, 1111. But wait, these can be shortened into Hex digits. 0000 is Hex 1, 0001 is Hex 2, 0010 is Hex 3, and so on up to 0111 is Hex E and 1111 is Hex F. So now the names of these Earths are EarthH1, EarthH2, EarthH3 EarthH4 ... Earth HE and Earth HF. So clone the tree again, and the new names at the branch tips becomes EarthH00, EarthH01, EarthH01, EarthH02, EarthH03 ... EarthH0D, Earth0E, EarthH0F, EarthH10, EarthH11, EarthH12, EarthH13 ... Earth H1E, EarthH1F. With a four digit Hex notation, by the time you get to HexFFFF, you have named 16^4 or 65,536 different Earths. AN 8 digit Hex notation gives you 16^16 or 4,294,967,296 names. Except, of course, who wants to be named EarthHBAD? Or EarthHBADBAD? Or even EarthHBADFAD? Methinks they would all get nicknames, instead. *EDIT* The advantage of this system is that you can clearly identify when the histories diverged. Every universe had the same history up until the first clone. So every universe that was 'odd' had a divergent history from the 'even' between the first and second clone. Every universe that had the first two digits '00' had the same history up until the clone that generated a third digit. Likewise every universe with a "01', a '10', and a '11' first LSB digits would have identical histories. Then after the next clone, every universe would match histories up until the next digit was added. Those with a '0' added would start to have a divergent history from those with a '1' added. Then they would all go through two divergent histories each identically into two streams at the next clone, which add another '0' or '1' to the name, indicating a desynch in the histories. At the next clone, every universe that had 'history 0101' would be identically cloned into two '10101' and '00101'. That is, universes 10 1110 and 11 1110 had identical histories up throughout the iterations 1110 (they were identical clones up to that time), and diverged only when the digit fifth from the right got added. However, a universe with designation 10 0110 diverged from all the universes with '110' as the first three LSBs up to the next clone of the fourth digit from the right (ie. 1110 vs 0110). Two earths 1110 0101 and 0110 0101 were cloned and desynched or diverged after the eighth cloning, having shared the exact same pre-cloned history up until then. So after another cloning, there would be four Earths, Earth 0 0110 0101, Earth 0 1110 0101, Earth 1 0110 0101, and Earth 1 1110 0101, with identical histories up until two clonings ago. In this way, an omnipotent accountant could track when the financial obligations diverged between two entities, be they individuals or corporations, on diverging Earths. ]
[Question] [ This question already has answers here: [How would one destroy a black hole?](/questions/36501/how-would-one-destroy-a-black-hole) (14 answers) Closed 4 years ago. For starters, the black hole is temporarily contained. But once it’s containment fails it will devour the planet. Obviously, that’s a bad thing. What’s a reasonable way to prevent that? Also the black hole is currently really tiny. Like 4 feet in diameter. It can be an outlandish solution as long as it would have a chance to work, and would not take long to implement Thanks. [Answer] A black hole with a Schwarzschild radius of 4 feet would have a mass of 137.5 x Earth and the gravity to go along with it. Such a black hole would instantly liquefy the earth as it shreds it into an accretion disk and shoots gamma rays straight through the earth's poles. There would be approximately 0 seconds for a committee to consider the problem before being vaporized, thus no solution will be found. For narrative purposes however, the author might wish to reconsider the mass of the black hole to one that is less instantly catastrophic using the following: [calculator](http://xaonon.dyndns.org/hawking/). For instance, a black hole with a mass of 72135 metric tons would have a radius of 0.0001071103 femtometers and a lifetime of approximately 1 year before it goes critical and destroys the planet. Such a black hole would be too small to interact with any atom inside the earth, so it would float freely, ping-ponging back and forth without ever acreting any more mass. A literal ticking-time-bomb if you will as it passes in and out, in and out through the Earth. [Answer] Feed the hole negative mass. Probably you have some negative matter around to power your Alcubierre drive. Load that into your little black hole. You will need a fair bit to make a difference. To my surprise, this is apparently a done thing in theoretical circles: adding negative mass to model the shrinking of a black hole via Hawking radiation. <https://physics.stackexchange.com/questions/153376/what-would-happen-if-a-negative-mass-crossed-the-event-horizon-of-a-black-hole> > > The situation of negative mass falling into a black hole does have one > important consequence though, in GR it's the only way for the event > horizon of a black hole to shrink rather than expand, and for this > reason a dynamical black hole metric (the Vaidya metric) with negative > mass falling into it is sometimes used when trying to model the > long-term behavior of a black hole that is "evaporating" due to > continually emitting Hawking radiation (since this is a quantum > effect, and general relativity is not fully compatible with quantum > mechanics, this evaporation should ultimately require a full theory of > quantum gravity to model it completely accurately, but it seems > reasonable to expect that the earlier stages of evaporation, before > the size of the black hole and the energy density approach the Planck > scale where quantum gravity effects are expected to become > significant, should have some close analogue in classical general > relativity). > > > [Answer] I will assume you want something vaguely scientifically plausible. (I will also assume when you said "small black hole" you really meant one that is small enough to be contained on the surface of a planet and that the 4' size was not what you really meant.) To start with, you can't destroy black holes. You can -- with difficulty -- move them. You can feed them and make them more massive. You can charge them and change their spin. But that's about it. So pretty much all you can do is try to get it up out of the planet, and that requires as much thrust as it would to launch the same mass of ordinary material into orbit and a way to apply that thrust to the BH. (It's true that BHs probably evaporate due to Hawking radiation (though it's never been observed), but if HR is real, evaporation takes a very long time.) The only way moving the BH might be doable (which wouldn't necessarily destroy the planet as a side-effect) involves charging the BH and then using electromagnetic fields to accelerate it. Pretty hard to do! That brings up the question of the BH's mass. If it was temporarily contained, then it must have had a large charge and been supported by EM fields. It's mass is its mass, and if it was a small BH -- say the same mass as a mountain -- the containment facility would need to be able to support that mass concentrated into a really, really tiny object. The [Schwarzschild radius](https://en.wikipedia.org/wiki/Schwarzschild_radius) of a BH of 100,000 tons (which would be very difficult to support with any imaginable technology) would be about 10-19 meters which is roughly 1 millionth the diameter of a proton. Something that small would find it very difficult to swallow anything, so while it would orbit inside the planet, it would grow only very, very slowly. It would probably come to a halt (due to dynamical friction) at the planet's core and just sit there growing very, very, very slowly. It would probably have no effect whatsoever on a thousand year timescale. The bigger the BH, the more of an impact it would have, but the less likely it would be that it could ever have been contained at the planet's surface. [Answer] For something that sounds plausible, but totally isn't Fire charged particles at relativistic speeds on tangents to the event horizon. And just before they cross the event horizon, slow them down to below relativistic speeds with bursts from powerful magnetic and electrical fields. As they near the black hole, their induced mass creates gravitation fields to compete with the internal mass of the black hole. By firing multiple particles simultaneously at antipodal targets tangential to the event horizon, the black hole can't move so its internal mass it stretched between the equal gravitational forces pulling it apart. By this means, tiny bits of matter can be teased away from the grip of the black hole. Keep it up until it is too small to hurt the planet. Scientists save the world, again. Your welcome. [Answer] A black hole with an event horizon circumference of ~13 feet (circumference because diameter is meaningless in a region of space so deeply curved) would mass far more than the Earth. The surface gravity of an Earth-sized planet with such a body at its core would be well beyond survivability of any land animal less tough than a small spider or insect (though aquatic creatures would be okay until they tried to dive too deep -- say, more than about ten meters). So, don't worry about destroying that four foot black hole. Everyone will be dead before it's known why the Earth is being swallowed -- and it'll never get near the center of the planet; it'll tear the whole planet up before passing without a noticeable change in trajectory. [Answer] Spin it up until its angular momentum becomes sufficiently large that it becomes a naked, toroidal singularity, at which point the laws of physics metaphorically throw up their hands and shrug in confusion. ]
[Question] [ This is a partial extension to this question: [What kind of natural armor would stop bullets?](https://worldbuilding.stackexchange.com/questions/96503/what-kind-of-natural-armor-would-stop-bullets) I was wondering if a creature could grow armor in such a way which would allow for it to detach a portion of the armor, and use it as a shield. It does not need to develop naturally, we have bio engineering on our side for this question. A couple requirements: 1. It needs to be somewhat easy to get off the body. 2. It should be able to be "reattached" to the body, and it would be nice if the armor could continue growing after being "reattached". 3. It should not be for the entire body, the detachable bit would be located on the back of the creature. UDATE: The reason detachable armor is developed is for inter-species fighting, where in some scenarios its helpful to have more forward facing armor, kind of like how knights used shields, even though they had armor. It would also work as "deployable" cover in times with guns, so those with lighter armor could still be protected from hostile fire. Not every creature gets the detachable armor, just like not every human in medieval times got a massive shield. [Answer] I'm going to suggest a parasitic symbiosis as the solution to this, the armoured "shield plate" on it's back is not in fact an integral part of the creature but is attached leech-like to its host. When circumstances warrant the host can send a chemical signal that loosens the shield's feeding tubes and allows it to be pulled off and used to shield the front of the host rather than its apparently less vulnerable back. When the danger is past the plate can be reattached to its feeding points and heal up/grow on until next time. Do note that if this creature misjudges the situation it finds itself in then popping its back plate is probably going to get it killed in short order. [Answer] Crustaceans do this routinely. [![lobster with shed shell](https://i.stack.imgur.com/bjDJ5.jpg)](https://i.stack.imgur.com/bjDJ5.jpg) from <http://www.public-record.org/video/lobster-shedding-it-s-old-shell-for-a-new-one/TDLb5WcSREM> When crustaceans grow, they outgrow their shell (their "armor"). So they split it, crawl out and grow new. There is a period once they are out when they are soft - the carapace or shell must harden over some hours. This is not exactly the same as the OP requests since the lobster cannot put it back on. But it is armor and it is detachable, and I can imagine something like a hermit crab carrying its old armor in front of it or on top of it like a shield. Some crustaceans (and also some sea urchins) put stuff on top of themselves for camouflage / armor - this hermit crab is carrying a fire urchin, which I think is about the most awesome shield a crab could have. Good looking too! <https://jurgenfreund.photoshelter.com/image/I0000l.4fjD9Vafs> [![hermit crab carrying fire urchin](https://i.stack.imgur.com/AqXOT.jpg)](https://i.stack.imgur.com/AqXOT.jpg) [Answer] # Yes but it's tricky to pull off This shield needs to do a couple things to be worthwhile. 1. Freedom of movement: It needs to be segmented to support movement while stowed on the back. Humans get away with strapping shields to our backs because the shield only attaches at two points. This shield will have continuous contact. If not segmented then the creature will need to be molded in such a way that this big plate doesn't impede movement. 2. Rapid Reattachment: The shield needs to support reattachment on the speed of seconds. Anything longer will require regrowing things and that takes too much energy (plus added risk of infection. Gross!) 3. Rapid Regeneration:Rapid hook-up to blood supply. This shield will need to regrow after being used. Blood supply means the shield can be a living thing. You'll probably want to design a crazy strong immune system to handle the inevitable infections. Also, this is totally unprecedented since there's no organism I know of that has what amounts to a external hydraulic valve for blood. # Segmented Shield, Detach! A couple things need to happen to make the shield useful. 1. Detach blood supply of shield from creature. Probably want to flush the blood from the shield back to the creature. This prevents blood loss when the shield is damaged and gives the creature a kind of battle-boost of blood. 2. Detach shield holding mechanism. The mechanism could be a bunch of gecko foot pad like things that grip or intertwine with the shield to hold it in place. 3. Make the shield rigid. There are a number of ways this can be done. It can be made rigid by attaching it to the forearm of the creature. 1. Rigidity would then come from the bones in the forearm though this seems dangerous to me unless the forearms are also strengthened for the added load. 2. Alternatively, have each plate interlock with it's neighbors. When there's blood flow to the shield, the space between the plates are pressurized, forcing them apart. This greater distance increases the range of motion. When there's no blood, the plates are elastically drawn back together, making the whole shield rigid. If the pressurized shield is hard to imagine, think of a spinal column. All the vertebrae interlock. Normally, they have a pretty small range of motion ~18 degrees. However, if you increase the space between each vertebrae, the range of motion is increased. 4. Clean up the cilia that hold the shield in place when not in use. # This is cool, why tricky? It's awkward because usually you want armor all over. Also, there's no precedent for this anywhere in real life. You want armor to stay attached for the life of the creature. If additional armor is required, it just grows in that location. There are a lot of bioengineering challenges that will need to be overcome to make this work. The creature would need to be designed specifically to its shield. Also, all the tissue in the shield will need to be able to thrive in an an anaerobic environment for hours or days when the blood supply is cut-off. This likely means that regrowth will stop during that period. [Answer] Yes, But It Might (Might) Not Be Bullet Proof Here is a link to an article about a recently discovered gecko as of February 2017 (Could be earlier) <http://www.cbc.ca/news/technology/new-species-gecko-tears-off-skin-1.3971889> It fits your criteria 2/3 times. This armor doesn't cover the whole body (I may be wrong though about this one), it detaches really quickly, and it regrows in a few weeks. Unfortunately they cant be reattached. About the bullet proof thing, there may be a workaround. Chitons are mollusks that make their own teeth out of magnetite which is the hardest material made by a living organism. If you could have a combination of the Gecko and Chiton, there you have it, Regenerative, Detachable, Possibly Bullet Proof, Natural Armor [Answer] How about this. Treat this shield more like the shell of a mollusk. * Abalone shells are incredibly strong and virtually bullet proof. * shells aren't directly part of their creature but a product of. * your creature could work on his shell for maintenance or growth whenever there is down time. could attach and detach from the shell via a muscle [Answer] Perhaps something along the lines of a rattlesnake's rattle. This forms when the snake sheds its skin, and a bit remains behind on the tail and hardens to form another link in the rattle. Granted, a rattlesnake's rattle isn't exactly armor (although the sound definitely serves as a warning), but a theoretical creature could shed a skin or shell that hardens like the rattle, and then carry that around. Bonus would be - it would get a new shield periodically, in case the old one was damaged or lost. [Answer] Many shell animals like oisters have a muscle that is attached to the uppershell. If instead it can grab hold of it and also let it go, you can have what you want. The armor would grow on a piece of flesh/skin that creates the armor substance. This piece is connected by detacheable bloodvessels, and the small area between the pieces is covered in mucus and such against infections. The creature can have it's muscles let go of the armor, the bloodvessles detach and the creature can take it off. If you have similar armor pieces at various places, you could replace a busted piece of armor with a new piece, allowing the busted piece to heal on a less vital/less likely to hit area. Or as mentioned you can carry the piece of armor as a shield. When re-attaching a piece of armor the bloodvessles also re-attach and whatever constricted it lets go. It's likely that the muscle(s) holding on to the armor will simultaneously support bloodvessles and nerve endings that connect to the armor. Its also smart to have dozens of small muscles hold on to the armor and to have the muscle basically lock a bony potrusion in place so that it doesnt have to expend energy holding it. Another advantage of this is slight movement capability of the platings to increase or decrease agility. Decreasing agility can help with adding more forces when pushing or lifting for example. Many operations on arms and legs happen by first taking the blood out, these operations can take up to 7 hours before the bodypart starts degrading permanently, so a piece of armor would likely survive for as much time as well. 7 hours is more than enough time for a battle, or temporary re-attachment. [Answer] a limb that folds back onto the creature's back, and with its extension shaped like a shield, would work. For example many kinds of crabs have one of its pincers very large to plug up the hole it lives in. When the creature is at rest, this limb folds back and functions as additional back armor/for easy carrying, and when in use, unfolds and docks to the creature's forearm, giving the impression that it is taking off a shield from its back. ]
[Question] [ In this imaginary future, everyone carries an implant like an RFID chip that identifies them to scanners that then authorize access or orders. Today, such chips are usually [implanted subdermally, often in the hand](https://en.wikipedia.org/wiki/Microchip_implant_(human)). But in a future where such chips are not experiments or gadgets for rare individuals and useless to anyone else, but ubiquitious and powerful, I think implanting them under the skin of the hand would allow criminals and hackers to tamper with them much too easily. So I wonder if they would rather be implanted in a place were they would be difficult and dangerous to remove, e.g. in the brain. Or am I overthinking the issue, as passports are not implanted safely either and still difficult enough to "hack"? Where would the president carry the implant that would authorize his order to launch a war? What would make it secure from hacking it remotely? I think it needs to be difficult to remove and the ID must be hardwired. On the other hand it must be possible to insert and remove such an implant when a person is elected or resigns from an office, without any danger to his life, so an operation on the brain every now and then seems to be out of the question. --- Please don't take the example of the president farther than is meaningful. The president today carries a passport as his ID. This is easy to steal, easy to fake. Still, the nuclear launch procedure is secure enough, as it doesn't depend on the president's passport alone. So of course in a future with RFID chips, the security of the nuclear launch procedure wouldn't depend on the president's chip alone. Also, RFID was an example only. If you can come up with a better technology to wirelessly transmit (or read) a person's identity, then that is even better. But it has to work with sunglasses, so reading the retina is out of the question. Finally, don't go over board. Nothing is unfakeable today, and we still get by. So nothing has to be totally unfakeable or unbreachable in the future. The requirement for security is that the chip has to be reasonably secure. Which, to return to the president, is why no sane person would rely on the chip alone in matters of national security. Keep the question in context. [Answer] Make it a distributed system You're worried that if it's implanted in the periphery of the body it could be cut out too easily and either re-used or dismantled as part of an attack. So make it two or more parts, linked by either hairlike wires or the user's own nervous system. Once live, cutting the link between the two parts will instantly disable both parts. (Various authors have written "neural lace" implants which are embedded across the brain and cannot be removed intact.) [Answer] Chips would be personal and for life (or until it breaks or is superseded). You wouldn't do chips for certain functions, you would program the systems to accept the existing personal keys of people, so you would not regularly need to replace them. This is easy if you know asymmetric cryptography. Existing cryptographic methods for protecting the chip (research credit cards) go without saying. Essentially you can just assume that it's really hard to tamper with the chip directly (without destroying it or triggering and alert or anything) and it's impossible to duplicate a chip or get at its secret. For the people who doubt this, there is a technical explanation at the bottom of the answer describing how such systems work right now. [1] To keep the chip from working outside of the intended persons body and so you can get a probability of whether someone is acting by their free will and whether the chip is really still inside the proper body: Make the chip monitor the health functions of its host, for example: * DNA * heart rate * blood pressure * oxygen level * sugar level * adrenaline level * alcohol level and presence of other drugs It could also monitor some other things, for example: * location * presence of other identities nearby * time of day When there are any abnormalities in this data, the chip can take appropriate measures. Examples: * pulse stops (and other signs of death or removal from the body): deactivate and require reactivation by an authority * drug presence: don't do digital signatures (so the intoxicated person couldn't sign a contract, but other than that, stuff would still work) * not in a secure location, unknown identities nearby, high stress level: don't confirm missile launches * drug presence: don't do missile launches either You could take that a step further and from all that data generate a probability that the chip is inside the proper person and that the person is acting by their free will (complicated algorithm). Then when the chip should authorize something, it also sends that probability and depending on the application there are defined minimum probabilities needed. [1]: Those chips use asymmetric cryptography. Each person has a public and a private key. Everyone has the public one (or can get it from a government system). Using the public key, people can encrypt stuff which can only be decrypted using the private key. So when A wants to know if B really is B, A takes Bs public key, encrypts a random challenge message and sends it to B. B then decrypts it and sends the decrypted message back. If B succeeds, then B must have the private key and thus is really B. During this protocol, the private key never leaves Bs systems. By listening to their exchange, you gain nothing, you can't calculate the private key from it. So the only way to find Bs private key is to cut open its authentication chip, search where the key is physically stored and get it out by directly probing the chips memory cells. This is a really expensive, difficult procedure and even with the resources of a nation state the probability of destroying the chip before getting at its secret is pretty large. [Answer] # The chips are as secure as the author says they are > > I think implanting them under the skin of the hand would allow criminals and hackers to tamper with them much too easily. > > > Just forget about Hollywood hacking. Cracking the security of a computer system in fiction is always dependent on how quickly the heroes / antagonists need to get inside to make the story exciting. In Hollywood, hacking will succeed if it is needed for the story. In real life it is both easier and harder to break computer security. Easier if you are dealing with people that do not take security seriously, or are incompetent. Harder, next to impossible, when you are dealing with people that know their stuff. A subdermal chip will work just fine for your purposes. Do it right and it cannot be "tampered" with unless you have ridiculous amounts of money and an entire national defence agency to back you up. And even then the results are far from certain. The only way it could be used out of scope for how it was intended is if someone chops off the limb in question, scoops out the chip and implants it in someone else. And that you can make some simple safeguards against, like making the "chip" be a film wrapped around the skeleton. The point is: the security of the chip will work if you as an author says it does. Some rather simple hand-waving will make it so that the implants are secure enough for everyday applications. And for those in your story that need extra security... well they will find ways to make the ID check better though for instance two/three/more factor authentication. So in the case of the President, the subdermal chip plus a code that they memorize, plus the [two-man rule](https://en.wikipedia.org/wiki/Two-man_rule) are more than enough for your purposes. [Answer] It's your story so the RFID is there wherever you want or need it to be and is as secure or insecure as you want or need it to be. However as this is Worldbuilding, I wonder firstly why would an RFID-like device become ubiquitous enough to use for identity? A body implanted device just for identity is a hard sell to a population in the billions or even hundreds of millions especially if there is any democracy and civil liberties left in the world. But I can see it becoming the equivalent of a Social Security Number in the USA. A non-documented, non-resident of the USA encounters tremendous difficulty conducting simple business without an SSN. This is getting harder with more and more regulation and data-sharing in banking & finance, government services and even medicine & insurance. But can an identity device get traction? Especially if any electronic device that can be manufactured can be cloned and artificial anti-copying steps become an arms race with the pirates. If the device was primarily beneficial for health and longevity improvement then uptake becomes a lesser obstacle. * Managing and reducing genetic and environmental risk factors relating to diseases (viral, bacterial, fungal, allergen). * Improving a body's reaction to stress, toxins, pollution, aging, drugs and other environmental impacts. * Allowing excess consumption of drugs, alcohol or food without negative physical consequences. * Delivery the benefits of physical fitness with relatively small physical workouts. * The simplest sales pitch would be "implant this device and you'll never get terminal cancer". In order for such systemic benefits to accrue, the device must become holistically integrated with the individual. That means sensors, probes and nanotechnology bots. Securing the device then becomes relatively easy as it monitors, interacts and spreads throughout a person's body systems (circulatory, respiratory, lymphatic, endocrine, digestive, nervous, urinary, reproductive, skeletal, muscular, integumentary). Side note: Such a human would be augmented beyond homo sapiens as their biology would be superior. Augmented humans would only reproduce with other augmented humans and have offspring that became augmented. The augmented would either become an elite or, if readily available to the masses, the un-augmented would die out. Now you've got a device that is essentially an interface between the technological augments of an individual and their biology. Those augments give a huge improvement in quality of life. At the same time the interface becomes a proxy for first order identity. It reports that it is embedded in the individual, in my case paulzag, and here is a packet of biodata to verify this identity. The receiving system makes its own biodata scans and determines access. Cyber-piracy stories can still be told as the interface attempts to pass itself and its host off as someone else. That would be expensive and technologically sophisticated. However information-security principles of multi-factor authentication would still exist. Especially with a president's ability to start a war with a push of a button. [Answer] You can have the chip function much like some implementations of 2 factor authentication system today. The chip generates a new access code every X amount of time based on some unique signature. Since the chip needs only to transmit this information it cannot be hacked wirelessly. If you have custody over the chip holder you probably already have power to force them to give you access to whatever it is you want so wireless hacking is the only thing I would be worried about. For things like nuclear launch codes it might be helpful to have some sort of a self destruct button for extreme situations in which case it might be useful to keep the chip in some place that is harmful to electronics such as inside the stomach. [Answer] A lot of people believe that a chip cannot be tampered with from a distance. [This is not true](https://en.wikipedia.org/wiki/Wireless_identity_theft), especially if you are setting your story in a future where technology has evolved. Assuming your ID must be wirelessly communicated, I assume that the informations (whatever they are) stored in the RFID-like chip are encrypted. The problem with traditional cryptography, though, is that if you have the key(s), you have everything you need to decrypt your code... And the keys are too stored somewhere. [Quantum cryptography](https://en.wikipedia.org/wiki/Quantum_cryptography) is said to be impossible to hack due to the fact that a "bit" of information alters its state when it's read (from third parties). Problem is: it alters its state when it's read by a machine too... and if a machine is expecting a certain sequence to launch the missiles, it means that there's too a key involved... Assuming the worst case, terrorists have the key(s). A wireless transmission of a code is really a bad idea, since what the terrorists would do is simply set a smart-antenna to track the chip from a distance, and read its informations. What's indeed difficult is actually to get to the president physically. So why bother with a chip, when a retinal scan (some users already pointed out that this is impossible to hack - and why can't the scan work with sunglasses? They can be "smart" ones, or the scanner can be), voice recognition, fingerprint analysis, password and a titanium bullet with a code inside hidden in the body are all things that need a physical abduction? In short: I wouldn't rely on a (single) code stored on a (single) chip. Especially if transmission is considered. [Answer] # Removal > > So I wonder if they would rather be implanted in a place were they would be difficult and dangerous to remove, e.g. in the brain. > > > Today, there are copy protection schemes for µC's that basically work by enclosing the µC in some kind of gooey mass that hardens up and then is quite impossible to remove without damaging the µC beyond repair. You would do the same in your future. Don't worry too much about where exactly the device is located, but implant it in a way so it cannot be removed without destroying it. Make the internal building blocks of your device flexible but very weak, like biological nerves, so any attempt to cut near them will invariably destroy them. Make it so it is very hard to use X-ray to actually detect them (it does not matter if you can still detect the general area where it is implanted), so you cannot use X-ray or other devices to find the place where you have to cut. Implement it in some part of the trunk, not in a part of the body that can easily be cut off (i.e. cutting off the arm at the elbow might just be what you could fathom in your world; but if you implement it in, say, the upper layers of the stomach, then ripping off the stomach might be too far "out" to be considered a problem). # Hacking vs. private/public keys > > What would make it secure from hacking it remotely? > > > That depends on what the implant actually contains. If you restrict yourself to a pure identity function, then it is pretty simple to make it hack-proof. It basically comes down to storing the private key inside the implant. Remember, when you rip out the implant, then it is destroyed. And obviously you will make very sure that the private key is stored nowhere else in the known universe, only the public key needs to be freely available. You will of course also design the implant in such a way that it simply has no provision ("code") to "read out" the key. The key will not be stored like in a RAM/ROM area, but actually part of the physical structure. This is all nothing special, it's just the way private/public key schemes work even today. The mathematics behind it are understood. All attacks against PPK schemes are either targetting bugs in the implementation or brute-forcing; there is by design no other way, the mathematics are sound and "perfect" (until they are found not to be, obviously...). Now that the function of the implant is minimal, extremely well defined, not subject to change, the real security dangers are outside of the plant. Attackers will concentrate on breaking the external computers that store your "permissions". I.e., somewhere on the nuclear launch site, there will be a store that says "this is the public key of the president; only a message signed by the corresponding private key will be able to launch the missiles". Nobody will even think about ripping out the private key from the president (because it is well known that that is quite impossible); they will focus on attacking that information in the nuclear site instead. # Replacement > > On the other hand it must be possible to insert and remove such an implant when a person is elected or resigns from an office, > > > No. The identity can stay from birth to death. The information that you are the president is stored somewhere else, not inside your body. If you need to roll out a new version of your implant because technology advances (e.g., switching from 1024 bit keys to 2048 bits etc.) or they tend to degrade after a few years, then just create a new implant and place it somewhere else in the body in addition to the old one. The new imlpant comes with a new private/public key and the identity of the old and new implant are simply coupled together externally. This gives you a nice time of running both implants in parallel, making it a trivial process (thinking in IT terms here), i.e. it is not so critical to update all worldwide stores of "permissions" for that person. Of course, your nuclear site would always require to use the newest, most secure key scheme. Your local grocery store could chose to accept your old insecure scheme for a few more years. [Answer] imaginary? They're actually doing trials with exactly such systems... Ostensibly to make it easier to find alzheimer patients who wander from their retirement homes, people are being implanted with RFID chips and other devices on a trial basis. [Answer] I will tackle this from the perspective of information security. An RFID is an element of multiple factor authentication, which can have one or more components from the categories below * something you know (a password, PIN) * something you have (a hardware key) * something you are (your fingerprint, specific way of speaking etc.) The general idea is that you should use more than one to reduce the risk (your password can be acquired/hacked, your hardware key stolen and your eye borrowed). An implemented RFID chip lays somewhere in between case 2 and 3. This is something wich defines you (if it is unique) and something you have (because it is in your body and not naturally part of your body). You may however remove it, as you can take someone's fingerprints directly from their fingers. In such a case I would look at improving the weakness of today's biometrics (the "something you are"), currently: * it is expected that an eye outside of the socket will not work with a retina scanner (which looks for some activity which suggests that the eye in in the right place). There is not enough public data on whether this is bypassable * Normally fingerprint readers make sure that there is blood activity. The fingerprints can be nevertheless faked, so this does not work that well. Make your RFID truly non-operational outside of the body. Note that this solves the question of positive identification but not the case where someone does not want to be identified (by removing the chip). In that case you can bind it to a key function of the body. [Answer] (Reusing parts of several other answers) This is not only an ID chip, but it is your own personal AI doctor! This doctor is distributed in several chips in important places, brain, heart, spine, liver etc. These chips monitor your health continuously and sending the information to a central register. (the AI isn't actually on the chips, but in this central register) If you develop some condition that requires medical intervention, you will get a phone call from a doctor asking you to come visit. Since most conditions will be detected much earlier than today, much time and money will be saved and much suffering avoided. Incidentally, this continuous data stream will also give away your position. Bad news for kidnappers. Kidnappers can obviously wrap people in tin foil or something, but that in itself sets off an alarm. Of course, in this Big Brotherish future, there will be HD cameras everywhere, so an alarm will be followed by pictures of the kidnappers being posted to all nearby police. If you move a chip from one person to another, the data stream will be interrupted and will give different data when it comes back. You would also need to move all the chips at once since they are talking to each other. If you anesthetize the person, this is very visible on the medical data. If you operate without anesthetics, the pain will also be very visible. The chips have a private key that is used to authenticate you. A different key is used to encrypt the data so that only the medical center can use it. While it could be possible to fish the authentication key out using electron microscopes, magnetic resonance or whatever, it would not be possible without removing the chip from the person. People can obviously remove or break their own chips, but then they will be non-persons. Apart from not being able to pay for things in shops, you will also stand out like a sore thumb. A camera or motion detector seeing a person where there is no ID chip will raise the alarm. Civil liberty types will be very unhappy about this setup, and this should be reflected in the story. It is up you whether these people are heroic freedom fighters or foolish paranoid Luddites. The best stories will result from making both perspectives seem possible. [Answer] ### You does not even need to implant it Everywere in public spaces, place automated scanners that verify the biometrics. If someone put a stolen chip, it will not pass. It possible to fake it in conjunction with fake biometrics tough.... but fake biometrics will require weird looking fantasies which stand out in the crowd. [Answer] # Method 1 Implant a unique read-only RFID chip with bio-compatible coating in the brain of each fetus in the mother's womb around the age of 3 or 4 week weeks. The brain is still in an early developmental stage and will grow around it so that the chip cannot be removed later. The chip must be hardened against destruction by anything which will not kill the person. # Method 2 Alter each fetus' genes. Encode an ID encrypted with the private key of the government, readable by everybody using the government's public key from a trivial sample of the individual's DNA with a hand-held device, or a reader at doors etc. The ID will be as safe as the government's key. The cost of sequencing the human genome falls faster than exponential and will soon be trivial: [![Genome sequencing cost](https://i.stack.imgur.com/aW9sb.jpg)](https://i.stack.imgur.com/aW9sb.jpg) ]
[Question] [ Closed. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it focuses on one problem only by [editing this post](/posts/6571/edit). Closed 9 years ago. [Improve this question](/posts/6571/edit) Consider this: A fallen spaceship is approached by a person of very high intelligence. Think of someone really really smart, like top 50 in the world. How long would take for such a person to grasp another culture´s language and how their technology works? Would it even be possible? Or what would take to make it possible? Even if we consider that the person making the analysis comes from the same planet, would be possible to crack the language? I live in the same planet as you guys and I cant read or understand any other language than the ones I already know. Narrowing it down: The person that makes the analysis has "immortal" lifespan. Comes from highly advanced culture, like elders, or the first ones in the universe. Member of a society extremely advanced that in the past was responsible for seeding other civilizations into existence. Now he must analyze one artifact (the spaceship) that was made from a civilization formed by descendants (not directly) of his own. Both civilizations didn't have any previous contact. But the beings are basically the same, lets go with essentially humans. Is it cheating saying that the elder has super-intelligence and therefore can crack the language and linguistic systems and symbology of the newer civilization? [Answer] It may be impossible. For example, consider the ancient Minoan script known as [Linear A](http://en.wikipedia.org/wiki/Linear_A), which we have been unable to decipher. We know the ancient Minoans were human beings and quite a lot about how they lived. They must have had words for things like "house", "farm", "mother", "child", and so on, but this has been no help in understanding their written language. For an alien species, even the most basic concepts about life and communication might be completely different, so we could be even worse off than with Linear A. There are a couple of ways in which it might be plausible for an intelligent human to learn the alien language: * There is a lot of material to work with. The spacecraft might have a massive archive that includes audio and video as well as text. If a sufficiently intelligent alien had access to the complete library of Netflix, it could probably learn to speak English even if it had no other contact with us. (In the process, it might get some highly misleading impressions of our culture...) * The archive is intended to be understood. There might be a non-intelligent computer system which is designed to teach aliens the concepts of their language, using pictures and (hopefully) universal concepts such as mathematics. It has been [estimated](http://www.bbc.co.uk/news/magazine-23407265) that it takes 1765 hours for an adult to learn fluent English from scratch. (Children learn much more quickly.) At 8 hours a day, 7 days a week, it would take about 8 months. So this would be the minimum length of time to learn fluent alien-language, given a sophisticated and cooperative teaching system. If we were trying to analyse recordings the aliens had made for themselves and reverse-engineer the rules of their language, it might take much longer -- years or decades would be plausible. [Answer] Depends: Take the [Voynich manuscript](http://en.wikipedia.org/wiki/Voynich_manuscript) as an example. While we know it was not written by aliens, we (as in, humanity) started trying to crack it in the early 1900s and just recently we [may found out how to crack it](http://www.beds.ac.uk/news/2014/february/600-year-old-mystery-manuscript-decoded-by-university-of-bedfordshire-professor). [Language is hard](http://en.wikipedia.org/wiki/Code_talker) and using a different language is always a good idea as a cipher (see link at beginning). Being [Czech](http://en.wikipedia.org/wiki/Czech_language), I can assure you that if that alien language is really different from the language the "elder" speaks, it could give him/her/it a hard time cracking it. Just as a joke: > > Příliš žluťoučký kůň úpěl ďábelské ódy > > > That sentence above is a pangram in Czech, featuring all the diacritic symbols in Czech. And talk about luck, my language uses the same alphabet as English language does. If we switch to Russian, a language from the same family as Czech, the fun increases: > > Эх, чужак, общий съём цен шляп (юфть) – вдрызг! > > > To return to the subject, I was talking about living languages the whole time. The alien language will be even harder — at the level of the manuscript I linked to above. You will naturally make the assumption that if there is picture of monkey with some text below, the text will be about... monkeys. But you could be wrong: ![The cover of the movie The Hangover: Part II. There is a monkey prominently shown in the centre of the image, with no surrounding text mentioning monkeys.](https://i.stack.imgur.com/yDdsb.jpg) [Image source](https://en.wikipedia.org/wiki/The_Hangover_Part_II) That's why you need a [Rosetta stone](http://en.wikipedia.org/wiki/Rosetta_Stone) to be found at the place. Otherwise, the cracking might take you forever. [Answer] Language might well be impossible because there isn't enough information. Technology is probably doable — in principle an artifact contains enough information to understand what and how it does. There are 2 conditions: 1. You don't accidentally destroy the ship and/or kill yourself. If you have no idea how a spaceship works (or what the warning signs say), accidentally turning on its nuclear/blackhole engines is a non-negligible risk. Thing get worse if it has weapons or anti-intrusion self-destruct mechanisms. Even a peaceful pro-safety life-support ship might do surprising things like violently ejecting lifeboats as soon as the hull is breached... OTOH an elder race probably does have full understanding of laws of physics and possible power sources, and non-invasive scanning techniques. Best scenario is atom-resolution scanning then safely playing with it inside a simulation. 2. It's not too advanced compared to your level. Being a genius in an elder race helps, but a descendant race might be even more advanced... This wouldn't make it strictly impossible but the research can take unbounded time. I think the best example we have for how advanced technology can be "indistinguishable from magic" is our biology. * If you are Aristotle you're a genius in your time but won't even figure out how blood is pumped around by the heart... * With current instruments and knowledge we have a great overall picture, productively study numerous low-level mechanisms and can develop interventions. It did take observation on millions of functioning humans to get here. (=> Having 1 spaceship might not be enough. Chances are way worse if no longer works.) By now the principles of most biological "design" don't feel alien to us: pneumatics, electrical/chemical pathways, organs & subsystems with clear purpose — we can't build like that (esp. chemistry) but we feel the purpose of it all. * DNA is harder. We're progressing steadily with reverse-engineering it but we have no idea how to develop it. Unlike human software, it seems to be a big tangle of randomness that happened to work together — we have no idea how to approach a big modification (e.g. produce healthy humans with wings), except by horrendous trial-and-error for millions of years and trillions of victims... For all we know, there may be no better way! * The brain is even harder. Having instruments and low-level understanding is not enough. We did reverse-engineer some fixed neural networks e.g. vision quite but we deeply have no idea how high-level cognition works. At some point a lot of signals flow, "magic chaos" happens, and it works... If you gave us perfect neural scans, even ones that we could simulate, we'd surely advance a lot on the low level but there is no guarantee we'll understand it. That's what "designed by aliens" feels like. [Answer] In James P Hogan's early novel Inherit the Stars, people find a lone individual in a space suit with some carrable equipment. They start to figure out reading from technical labels: figure out what voltage the thing was designed to use, and you have a guess as to what the label at the power connector states. The dimensions of items are biased to the units of measurement. In another famous story, a library of technical journals is found. The use a wall hangings in the classrooms as a Rosetta Stone: the periodic table, illustrations of elementary mechanics, etc. The point of the story is that even with no common point to relate to culture, science and engineering form a universal common area of understanding. [Answer] do you want to understand their language, or their technology? learning the technology could be easier then the language. If you put me down in front of a switch board made by someone with a different language I can still hit switches to see what happens. Even if you give me a complex system I can still dissect it and analyze it using my understanding of physics, which is universal, to translate it. Learning the technology without the language is a far more achievable goal. As to how long it takes, that depends on how advanced the two are, and what technology/knowledge gap may exist between them. ]
[Question] [ I want to create a world for my colonists that's bleak and unwelcoming as well as alien and strange. So to that end I wanted to make mushroom-like fungi the major flora on the planet. I've read [Where do mushroom forests thrive?](https://worldbuilding.stackexchange.com/questions/59005/where-do-mushroom-forests-thrive) for some inspiration. I don't need forest-sized growths, but to make it more alien I thought having a calcium carbonate structure would give a ghostly white appearance, similar to deep-sea coral that have made this trade-off compared to soft coral that uses chitin. But what would give rise to this? What is gained for swapping chitin for calcium carbonate? The only thing I can think of is that it would be necessary if there were extreme winds, but even then I'm not sure. [Answer] Moderately elevated calcium and CO2 levels. Chitin is a relatively expensive skeleton to use. It is a decorated version of cellulose, which contains energy like starch; think of how wood burns. All that energy has to be diverted from the metabolism of the organism that makes the chitin. By contrast, calcium and carbon dioxide in water (such as "hard water" from the tap) can spontaneously produce calcium carbonate, if the product of the concentration of calcium and carbonate are high enough. CO2 + H2O ⇋ H2CO3 ⇋ H+ + HCO3- ⇋ 2H+ + CO32- So under the right circumstances (high calcium, high CO2, alkaline conditions) the skeleton is free! (True, under those conditions calcium and/or carbon dioxide are being removed from the environment.) Note, however, that if your soil doesn't have abundant calcium, these fungi cannot make it, unless they evolve to do nuclear transmutation. The Achilles' heel of this approach is that any acidic environment will reach these "cell walls" and turn carbonate to bicarbonate to CO2 and release it, destroying the skeleton. Calcium carbonate skeletons are best hidden inside a body or else used in gentle seas that might naively have imagined no one was going to acidify them in a planetary ecological catastrophe. [Answer] Size There is a reason that after a certain size creatures use bones. Weight and strength. The weight for effective strength in chitin exceeds a threshold, making the creature too heavy and possibly collapse on itself. Bones on the other hand give structure and points for your body to be grafted to. This reduces weight by huge amounts. Your mushrooms can be of a huge size that makes a simple chitin ineffective. To still be viable, they slowly grow a skeleton like structure. This can happen automatically, where hormones of cells experiencing certain pressures triggers the growth, possibly on the underside of the mushrooms. It might not be fully clad on the underside by bone, but bonewhite tendrils throughout with varying thickness can be chilling already, possibly contrasting some colour. Alternatively this bone structure can seep partially into the surrounding cells, making them bone white (and posdibly hardened) as well. [Answer] If the environmental conditions make it more convenient to use calcium carbonate than chitin, it makes sense that natural selection will favor it. For example if calcium carbonate is readily available in the environment on this world, while chitin needs to synthetized, it can make sense that calcium carbonate is preferred as "cheaper" material. [Answer] Edibility, or more precisely the lack thereof Humans have an enzyme, chitinase, which digests chitin. Calcium carbonate is a lot harder (no pun intended, well not much) to use as a food source. [Answer] Chitin isn't as strong as bone, so the mushrooms would need bones for support for larger sizes under stronger gravity. And yes, it will help if you've got a very windy planet. Another reason why would be if we had a planet that's got calcium-rich soils, an alkaline environment, and higher carbon dioxide levels than Earth. These fungi could produce calcium carbonate via their internal water supply, and use it to build skeletal structures using a mechanism similar to the mending of broken bones in humans. And because a mushroom that bleeds would be creepy AF. The increased carbon dioxide would also make the planet, assuming an Earthlike albedo, orbital radius, and solar intensity, a bit warmer than Earth, and the white could help to reflect excess radiation. Of course, the fungi would need a way to absorb calcium, and the metabolism of fungi produces carbon dioxide, so they would hold onto it for use, and then release it. Probably the mycelium absorbs calcium. ]
[Question] [ Suppose that for some reason gravity magically changes, but only for people. While this goes on, instead of gravity pulling people down, it pushes them East. To be clear, it's just people. Not animals, not objects, and not their buildings. People fall east, but everything else falls to Earth like normal. My understanding of construction and materials is that there are a lot of things that can handle insane amounts of a certain type of force, from a certain direction, but change the type of force or the direction it pushes in and suddenly the material or structure falls apart like a card castle. Would this happen here? If this happened in the middle of a normal business day at some large skyscraper, filled to the normal acceptable capacity, and then everyone inside of it suddenly started being pushed sideways instead of pulled down, would the skyscraper still stay up, or would that amount of human weight pushing it sideways be more than it could handle? [Answer] ## According to [Evolution of Concrete Skyscrapers: from Ingalls to Jin mao](https://web.archive.org/web/20070605133019/http://www.civenv.unimelb.edu.au/ejse/Archives/Fulltext/200101/01/20010101.htm)... It's extremely Unlikely. The force needed to to effectively topple a modern sky scraper would be about 30% of its weight (above the 1st floor or so) in any direction perpendicular to a shear wall. This is for all skyscrapers built in the late 50s onwards, older buildings which exceed 15 stories will be a different story. This is because modern sky scrapers actually use tension to keep the shear forces in check. For example, with high wind conditions, The side of the building which is down wind actually has the most tension, due to what the author calls cantilevered systems. So what would it take to topple a mammoth? well, if you had a high rise which was 100 stories high, and 200 people on each floor, weighing an [American Average](https://www.healthline.com/health/mens-health/average-weight-for-men) of 197 lbs, gives us a whopping 1,970 imperial tons. Considering [the average skyscraper weighs](https://www.quora.com/How-much-does-a-skyscraper-weigh)around 225,000-250,000 tons (let's say 50% of the weight is below the 1st floor), the people would only weigh 3.57% of the force needed to break the tension system and cause critical failure. The much more likely instance is the breaking of every window of the building (or close to). [Answer] Reinforced concrete and structural steel are not so strongly directional as, for instance, carbon fibers. They would handle a change of load better than, for example, the suspension arm of a F1 car, which can withstand tons of load in the vertical direction but shatters with a minimal horizontal load. And if you think of it, it must be like that, unless you want your skyscraper to collapse with the first strong wind that blow around. However there is a problem: windows would become the standing surface for all the people in the outside facing rooms. I don't think that a window is designed to sustain that type of load. Same would happen for some internal non structural walls. I.e. the 25 floors building where I work, most internal walls are made of drywall, not exactly an excellent material to sustain standing people. So, the building would stand, and the eccentric load given by the East attracted humans would be quickly thrown off the building by the shattering windows and internal partition. [Answer] # The sky-scraper would not even care ### Because otherwise people could bring down skyscrapers with their own bodyweight Think about it this way: If I run as fast as I can and jump against a wall, I can create more force than my usual body-weight due to gravity. Now - if a skyscraper could be brought down by some hundred people running and jumping against the wall we would have a serious problem! - Sky scrapers can resist a whole lot more force. Maybe some people would create more force, if they fell more than 15 meters sideways without hitting anything before hitting the outer wall, but they will not change the order of magnitude. Think of 9/11 where a whole plane full of people hit a building sideways and it did not topple over by the impact and this was tons of steel in addition to the people inside the plane. ]
[Question] [ Considering that oil is only really prevalent on earth (where dead biomatter can be compressed over millions of years into long hydrocarbons) I began to think that plastic might be just as rare as wood in an interstellar/interplanetary civilization. Metals are very common in space, whether it's from asteroid mining or planetary sources it seems like metals could become so prevalent they'd be nearly worthless (or at least super cheap to purchase and use in product manufacturing). If that were the case, then most products you'd see people using would not include plastics, they'd be made primarily of metals. I'd imagine it a bit like Blade Runner or Cowboy Bebop, where wood and natural products are an extreme luxury. But then I read that planets like Titan have large amounts of hydrocarbons on them (which could be processed into oil/plastic products). And now I'm not sure if there would be a difference at all. I'm definitely assuming that power/travel are a non-issue in the scope of "Interstellar/interplanetary civilization". I'm most interested in the comparable amounts/distribution of metals vs plastics/oils. [Answer] Metal William of Ockham, an English Franciscan friar (1287–1347), is credited with formulating the Law of Parsimony that we know better today as Occam's Razor, which can be simplistically stated: "All things being equal, the simplest answer is usually correct." Plastic requires the stuff of life to manufacture. If our own solar system is any basis for judgement, most planets won't have the stuff of life. Ergo, no hydrocarbons. Ergo, no plastic. On the other hand, one can expect metal to be found on pretty much every non-gas-giant planet.1 And one must assume that an interstellar/interplanetary civilization has conquered the problem of efficient transportation and operation in the inhospitable vacuum of space. Therefore, mining non-life-supporting planets, asteroids, etc., isn't a problem. Conclusion While plastics will trump metals on life-bearing planets, the near infinite supply of metal outside those rare and precious spheres must prevail. Shipboard facilities will not be geared to plastics, but to metals, and that will carry over to their support facilities at all planets. Yup, metal. --- 1 Frankly, you'd find metals on gas giants, too. It's just a tad difficult to mine, that's all. [Answer] I like [JBH's answer](https://worldbuilding.stackexchange.com/a/147577/21222) and I agree with him. But just as a mental exercise, I'll defend the opposite point of view. ## Plastics. Because [Wikipedia says:](https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements) ![Elemental abundance](https://i.stack.imgur.com/9tDEz.jpg) There is much more carbon than iron or any other metals around, and most of the carbon is in interstellar clouds where you don't have the costs of navigating a gravity well. If you've got spare time and you are able to grow plastic-producing bacteria, you can make a lot of plastic very cheaply. [Answer] Metal (assuming you're in space.) In a space-faring civilization, there are a few assumptions we can feel entitled to make. The first is that metal is plentiful. Plentiful under these circumstances means that said civilization has entire asteroid belts of mine-able metals to work with. An army of replicating solar-powered drones should be able to burrow through asteroid belts and send usable chunks of pure metals across space to refineries. Also, solar power. Solar power isn't so great on Earth, because we can only collect it for half a day (more like a quarter if the solar panel is fixed) and there's weather like clouds and storms and the atmosphere itself which stop us from getting solar power. We still can, though, just not as good as we can in space. Which is more. So power, and metal is plentiful and (most importantly!) not locked behind gravity well likes plastic is. So - plastic - composed of hydrocarbons (not common in space) and can be made with less power than metal objects of a similar variety, and have decent utility (doesn't rust, for one), but locked by massive gravity wells -> probably sees use on planets with heavy life, which can access it without paying the cost of the gravity well. Everywhere else - metal. [Answer] Hmm. Let's posit a few supply chains: Thermal heat is easy: Mirrors to concentrate sunlight. Cooling is a challenge. You can create coolth with refrigerators dumping the heat via radiators open to deep space. Material movement is cheap like borscht if you are willing to wait. Minimum energy transfer orbits. Linear motors become mass drivers hurling a standard weight package anywhere in the solar system. You have to balance their use. Momentum is still conserved. But a mass driver in orbit around the moon can alternate a batch of parcels in opposite sides of it's orbit and nearly cancel out the effects, stealing momentum from the moon itself. Metal: You mine asteroids. The metallic ones are mostly iron and nickel, with traces of stuff like gold, iridium, platinum.... You melt them with very large solar mirrors. Have to invent processes for dealing with molten metals in zero gee. Plastic: You use gas giants as a source for hydrogen, Titan as a source of methane. You collect the gas with ram scoops dipping into the upper atmosphere. Methane => ethylene ($C\_2H\_4$) monomer which can be linked to form polyethylene. Methane can be used as a feed stock for the entire hydrocarbon industry. Silicates: Stony meteors, and the crust of most moons have a huge component of silicon dioxide. This is probably the base source for most of the oxygen your people will use, $SiO\_2 +CH\_4 + energy => H\_2O + O\_2 + Si$ But silicon dioxide is basically sand, and can be made into high temperature glass by itself or a lower melting point glass with the addition of calcium carbonate. Check the composition of 'stony meteorite' to see what you have to work with. So the overall answer is "Neither" Since it's abundant, and high temperature is a matter of making big mirrors, I expect he cheapest material to make will be glass. Glass fiber + polyester resin = fiberglass -- principle structural material. Molten glass + foaming agent => foamed glass, cellular glass. This can be made in various densities from heavy styrofoam to the density of glass. As such it would be an excellent insulator, and would be the most common way to make non-structural building components. Tempered glass makes containers, windows, pipe, utilitarian objects -- most of the things you use plastics for now. [Answer] Depends on the technology of the society, and how easy they find it to get into space from the bottom of a gravity well. There are asteroids entirely made of metal, but Titan has entire hydrocarbon oceans that could be pumped up and processed much more easily than asteroids can be mined. [Answer] # Metals This is simply based on energy economy. Plastic can be made from any source of carbon and hydrogen (some other elements as well). All of those elements are easy to find. However, turning raw hydrogen and carbon (after extracting from whatever it is currently bound to: i.e. H from water ice) is very energy intensive. As has mentioned, if you have planetary conditions that create hydrocarbons, that decreases the cost of making the longer chain molicules that are needed for plastic. Metals, on the other hand can generally be had by simply melting them out of whatever ore they are in (some metals take a bit more work). That makes metals the easiest and least costly to use in most of the galaxy. [Answer] I think that if the advanced interplanetary or interstellar society has highly advanced technology they should be able to form metals out of metallic elements and compounds scattered in space rocks even if no metallic asteroids are available. And they should be able to make plastics out of the various elements which make up plastics, and they will get those elements out of various space rocks such as asteroids composed of lighter elements, and comets. And they will also be able to break down asteroids, comets, and the surfaces of planets and moons into elements and compounds which they will use as materials to synthesize various futuristic composite materials that are superior to metals and plastics for various purposes. Thus it is hard to predict the relative percentages of metals, plastics, and other materials in the future space civilization, since there will be thousands of materials which can possibly be used and thousands of different purposes to use them form, and the widely differing properties of materials and requirements for various purposes will mean that many different materials will be the best to use for at least one purpose. Note that the best maerials fo ruse ninside an artificial Earth enviroment might be the same materials that are best for that purpose on Earth today if no better materies for that purpose happen to be developed in the future. But the best materials for use outside in the conditions of outer space or on the surface of an alien plent or moon is a different matter. GeraldFalla's answer to this question - [What could a self-sustaining lunar colony slowly lose that would ultimately prove fatal?](https://worldbuilding.stackexchange.com/questions/147462/what-could-a-self-sustaining-lunar-colony-slowly-lose-that-would-ultimately-prov)[1](https://worldbuilding.stackexchange.com/questions/147462/what-could-a-self-sustaining-lunar-colony-slowly-lose-that-would-ultimately-prov) - shows that many materials deteriorate in a space environment. ]
[Question] [ Given a system similar to the Earth/Moon/Sun system, how would one go about making solar eclipses rarer than they are here on earth, but keep new moons similar to how they currently are (or at least similar)? At first I thought that increasing the lunar tilt from 5 degrees to, say, 10 degrees would help, but there would still always be two "nodes" indicating where solar eclipses could happen on the planet. Even at a 90 degree angle, twice a year, the planet would see solar eclipses. at 10 degrees, new moons would still be relatively as frequent, though at 90 degrees, I don't think there would ever be a new moon. --- Is there a way to make total solar eclipses happen infrequently, while keeping new moons frequent? And if so, what variable(s) need to change to make that happen? [Answer] Keep sun and moon sizes, make the orbit of the Earth around the sun more excentric and with a smaller mean distance. The new moon is unaffected, but full solar eclipses will only happen if the eclipse happens together with the Earth's apoapsis, or close to it. And that will only happen during a few specific days of the year. Any solar eclipse far from the apoapsis will be partial or annular. That also implies shorter years and a whole different set of conditions on the planet that might not be compatible with life as we know it, though. [Answer] Just shrink the moon by 6%, and there will never be another total solar eclipse, but new moons will still happen as normal. The moon will be too small to fully cover the sun, so there will be partial and annular eclipses, but no total ones. If you still want the occasional total eclipse, make the moon slightly bigger again, so that eclipses are total if and only if it happens to be at the closest point to the Earth in its orbit at the time of the eclipse. We’d still get the same number of eclipses at the same time, but hardly any of them would be total. Since both the moon and the Earth are in elliptical orbits, the apparent angular sizes of the moon and sun vary. Specifically, the moon varies between 29' 26" and 33' 30" while the sun varies between 31' 36" and 32' 42". You want the moon’s maximum to be just larger than the sun’s minimum, so that there are very occasional total eclipses if we happen to get an eclipse when the moon is at its closest and the sun is at its furthest. So to reduce the moon’s maximum angular size to 31’ 40” you need to make it 5.5% smaller without changing its orbit. [Answer] Why not make the moon's orbit [precess](https://en.wikipedia.org/wiki/Precession)? If the precession chases the sun (from the perspective of earth) while staying a bit off from it, you could keep new moons as common as always and eliminate solar eclipses altogether. If you made the presession not quite at the same rate as the sun, you could also cause large periods without a single solar eclipse, followed by a period where a solar eclipse happened every month (which, from a story perspective, could be interesting). Alternatively, if you had the moon precess in the opposite direction of the earth's movement around the sun (and depending on the length of your lunar month vs solar year), it may be possible to have the moon 'miss' a solar eclipse except for once every few hundreds of years. [Answer] Resonance. Pick a ratio of the lunar orbital period to the solar orbital period such that the moon normally in the wrong part of it's orbit when it's both directly sunward and in the plane of the ecliptic. The bigger numbers you need to use to express the ratio the longer it will be between eclipses. Unlike normal planetary resonance orbits no force will maintain this or cause it to come into being but as the moon slowly spirals out there will be a time that it happens naturally. You'll have to adjust the size of the moon so it provides a total eclipse at that distance from the Earth. [Answer] At 90 degree inclination, you could still get new moons near the nodes where the inclination of the moon's orbit with respect to the line from the planet to the sun is low. The presence of nodes in the planet's orbit where the inclined orbital path of the moon intersects a line pointing towards the sun, however, is not itself problematic, because it is not itself sufficient to cause eclipses. And that's a good thing for you, because it's a simple geometric fact that you can't avoid them. In order to get an eclipse, the moon also has to actually pass through that intersection point during the brief period when it exists every half-year. As such, a very simple solution to avoid ever having an eclipse presents itself: just tweak the moon's orbital period so that it forms a simple integer ratio with the year, such that the moon is always in the same phase on the same date every year--and then just declare that the phases are such that you never have things line up for an eclipse. [Answer] Instead of one moon which is just big enough and close enough to cause a total eclipse whenever it intersects between our planet and our sun, why not have several moons which are each either smaller or more distant such that no single moon can produce a full eclipse. New moons would still happen and would actually be much more common than Earth standard, but total eclipses would only occur when all of the moons simultaneously entered the intersection point, each blocking a portion of the available sunshine and collectively blocking it all. [Answer] Another way to make total solar eclipses rarer would be to have a double sun. The planet would orbit both stars in a circumbinary orbit. Perhaps each of the stars and the moon have about the same apparent diameter as seen from the planet. So in a typical eclipse the moon might eclipse only one of the stars and leave the other one unblocked or maybe pass between the two stars as seen from the planet and not eclipse either star. The two stars would orbit around each other several times during each year of the planet, and the moon would orbit the planet several times during each year of the planet, and the three periods might not have a simple relationship. Also the three planes - the one in which the two stars orbit, the one in which the planet orbits the center of gravity of the stars, and the one in which the moon obits the planet, might not be the same plane but might be tilted in relation to each other. Thus there would only be a total eclipse of the two stars when one of the stars is in front of the other one, hiding it as seen from the planet, at the exact moment when the moon is passing in front of the nearer star, hiding it as seen from the planet. And it is possible such such a moment might happen only once in ten years, or once in a hundred years, or once in a thousand years, when everything aligns just right. [Answer] Have a moon with a high eccentricity orbit. Have the sizes such that only close it it's perigee (point of closest approach to the earth) is it large enough to get a total solar eclipse. At other points in the orbit it is further away and thus appears smaller in the sky than the sun. Also helped by the fact that orbiting objects move faster at the times of closest approach (due to conservation of energy), so the time spent in the eclipse zone is even smaller. The more enteric the orbit, the faster the moon shrinks in the sky after each perigee, so the less chance of a total eclipse. The flip side is that more of your new moons will occur when the moon is pretty small in the sky. [Answer] Make the moon's orbit very eccentric (as well as very inclined). When it is far from the planet (which is most of the time, given [Kepler's Laws](https://en.wikipedia.org/wiki/Kepler%27s_laws_of_planetary_motion)), it is too small to cause a total eclipse. The two times a year when the moon passes in front of the sun would have to coincide with the fairly short fraction of its orbit when it is close enough to the planet to totally obscure the sun. [Answer] Another option I couldn't find yet would be to make the moon revolve slow enough around Earth that it would always be on the far side, away from the sun. It's an extreme version of the syncing mentioned above. And it could be stable, in the same way the moon's rotation is stable locked to Earth. We'd never have a solar eclipse and lots of new moons. It would be even more stable if Earth was tidally locked to the Sun as the Moon is to Earth. On a side note, if the moon was in the Lagrange point between the Sun and Earth, we'd never see the Sun... [Answer] Another option would be to make the eclipses very regular but make them land on a part of the earth where people generally aren't. Not being an astronomer, I might suggest that we move all land masses north and south of the tropics, and set the moon's orbit exactly the plane of the earth's orbit of the sun. It seems to me the eclipses would always fall in the tropics, and if you have enough sea monsters people will never see them... ]
[Question] [ I'm making a world where approximately 75-90% of humanity was taken out by a non-biological weapon (i.e., no viruses or bacteria), but the majority of major structures, such as tall buildings, exist almost untouched (just normal wear and tear over about 150 years or so). What kind of weapon would be able to do this? It is not necessary that the weapon be conventional/nuclear (could be genetic experiments or some such), but 1. majority of human population died and 2. the agent had completely run its course within 5 years and stopped existing either simultaneously (preferred) or within another 25 years or so (increasingly not preferred). I don't need valid scientific processes (they would be preferred), but I do need to be able to give a very logical explanation for why it had the effect it did. Science partially survived, once people managed to get power back and get the computers and such on (75 years ago), so BS would have a flashing red light brighter than Times Square at night. [Answer] 1. Some kind of radioactive weapon that doesn't explode, but instead leaks massive doses of radiation into the environment. Plants, humans, and animals would die, but human structures would last until they eventually collapse from lack of human repair. 2. An ice age. Whether it is caused by a supervolcano, a mini nuclear war, or some kind of environmental factor, a global Ice Age would collapse our food supply. Those who didn't die of starvation would likely die in the wars over the last bits of food. While some of your cities might be destroyed by war or whatever cause your ice age, a majority of would still be intact. 3. Global electro-magnetic pulse wipes out all electricity. This might not kill 75-90 percent of your population, but I think it could easily make 50 percent from the starvation and wars that would follow this event. 4. Something nanite related. Here we get more into science fiction. Part cybernetic, part biological, they can be programmed to multiply and kill off humanity but leave human structures alone. [Answer] While I personally like the answer provided by @BryanMcClure, I feel like I should at least weigh in with this possible answer of simplicity. Based on what you've said you wanted the effects of the weapon to be, it sounds like a neutron bomb fits your need almost perfectly.[1](http://www.nuclearfiles.org/menu/key-issues/nuclear-weapons/basics/neutron-bomb.htm) The variable here that might need to be manipulated in order to support the full range of your scenario would be the half-life of the radiation released. Since it's your narrative, you could always come up with a convincing reason that the half-life involved was either brought under control somehow (i.e. reduced timeline), or was of a desired half-life to begin with (for your premises to be supported). Pertinent excepts from the web source (provided above) "The tactical neutron bomb is a nuclear weapon that maximizes damage to people but minimizes damage to buildings and equipment. It is also called an enhanced radiation warhead. The neutron bomb is a specialized thermonuclear weapon that produces a minimal blast but releases large amounts of lethal radiation..." "The idea of the neutron warhead has been hotly debated since its inception. At the time of its introduction, some felt that its relatively small initial blast and fallout was ideal for use in densely populated areas, like Europe." [Answer] ## Use Neutron Bombs These are very effective for the problem posed. ## Scope Killing 75 to 90% of the population means eliminating humans from [Asia, Europe and Africa](https://en.wikipedia.org/wiki/List_of_continents_by_population). The population of the America's isn't quite 1 billion so we'll leave them alone (for now). Since the question explicitly states "weapon", the cause of death must be a man-made device. Super massive coronal mass ejections, rocks thrown at Earth, or other fun one-shot events aren't in scope either. ## Kill everyone with Neutrons There's a type of nuclear weapon called a [neutron bomb](https://en.wikipedia.org/wiki/Neutron_bomb) that releases a significant portion of the bomb's energy in the form of gamma radiation and neutrons. There are still thermal and blast effects but these are relatively slight compared to the gamma and neutron emissions. Also, neutron bombs are relatively low yield, <15KT. In larger weapons, the thermal and blast effects dominate the neutron emissions, so that isn't useful for our purposes. Neutron bombs won't be able to kill everyone directly. That's just too many bombs over too large an area. However, neutron bombs make excellent area denial weapons and that will be our primary use of them. The primary focus of the attacks will be urban population centers and food distribution points. Some destruction of tall urban buildings is inevitable with this approach though the blasts could be planned to minimize this damage. Area denial from a properly designed neutron bomb lasts about a year. ## Targeting Priorities By irradiating the population centers and food distribution points, billions of people will die immediately. This is preferable to attacking just the food distribution network because starving people will fight for food, thus destroying more buildings in the process. The secondary effects of denying access to food distrubition and urban centers is that the economy of attacked countries go into massive depressions and widespread starvation in surviving urban and suburban areas. ## Building enough weapons This is tricky. Because neutron bombs have a comparatively light yield, this attack will require tens of thousands of weapons. Across Africa and Asia, there are 2813 large cities covering 171,984 km^2 according to this [spreadsheet from the Lincoln Institute](https://www.lincolninst.edu/subcenters/atlas-urban-expansion/documents/table-urban-land-cover-data.xls). With that many weapons, the attack will need to account for duds. The industrial infrastructure to build that many weapons would exceed or equal the combined nuclear weapons production capacity of the US and the USSR during the 1960s. That kind of activity is going to be noticed by someone but , it just works. [Answer] So, I think I've figured out a good way to do this: A government gray-hat genetic research element went rogue when their department was about to be downsized because public perception of their program became incredibly negative, and proceeded to use their remaining time and funding creating their revenge-the rabids. The rabids, intended to be release in select locations around the world to cause havoc and only this lab would be able to stop them, thus forcing the government to reinstate and substantially increase funding and positive publicity. However, the rabids escaped containment en route, being far more clever than their creators had anticipated, which meant that the locations carefully selected by psychologists to make people more willing to help genetic research were not targeted nearly as precisely as had been hoped. This breach in containment therefore caused mass panic, with looting and vandalism, though nearly all buildings survived at least mostly intact. The rabids spread quickly across every continent, petering out in the far cold reaches, but raging ahead through: * deserts * jungles * forests * plains * mountains * and were nearly unstoppable One small batch, having been marked for destruction as "failures," escaped before they could be terminated and destroyed the facility, trashing the place (intentionally) so that no one could find a way to stop them. Soon, however, the remaining few governments and world leaders began launching nuclear strikes at the rabids (who preferred to remain in dense clusters away from cities, only coming in because killing humans was a strong biological need built in) irradiating much of the earth and causing a huge swath of destruction, while leaving cities mostly intact. The surviving rabids eventually managed to root out all but the hardiest and most remote survivors, including all world leaders and militaries. But a problem soon emerged: they had been built with a genetic "stop-clock" that would cause the rabids' cells to mutate and cease normal separation and functions after a number of years, effectively killing them. This took place slowly enough that, over several years, the rabids became increasingly stupid, rotting creatures, that would eventually become so mindless that they only followed their basest biological impulse: kill humans. Eventually, without a source of food, even these despicable creatures began to die off, becoming almost completely extinct by 2091 (apocalypse began in late 2082, nuclear strikes were early 2085). Having no methods of reproduction, they had no options left; they just died. Now, in 2267, my story takes place. Humanity began emerging from hiding in the early 2250s, and the population soon began to rapidly grow once again. Each group thinks that they are the only survivors, except for the groups in Antarctica and Patagonia (now ironically called Southgate), who had managed to establish electronic contact with each other due to the relative distance and electrical/engineering skills of both locations. In addition, there is also a group in Russia (community called Kraques-settled in a glacial ravine), one in Iceland (still Iceland, population completely untouched entirely but the distance was too great for communication with the Antarcticans and Southgaters), and a group in Canada (called the Inyukon community). It is approximately 1 year before the arrival of the experimental ship Colombia 9.8, equipped with a phantom-field generator, is due to return from its first long-distance voyage and the final test of the long-term deep space survival ability of the ship. The Antarcticans, and by extension the Southgaters, know of this. In no other place does anyone remember that humanity once made it outside the solar system (the return of the ship was supposed to be received with tons of fanfare and everything-this project was what took the funding from the lab for the final development and deployment). The vehicle launched in the year 2069, and was due to return exactly 200 years after they engaged the drive. The Antarcticans barely even remembered this until they were reminded in 2267 by a preset and unknown alarm of the impending arrival, and only because the facility there was primarily scientists, researchers, and astronomers, who were there to begin the building of an indefinitely self-sufficient and sustainable community. I know this is long and convoluted, but it is basically my prologue and 1-5 chapters summed up. [Answer] I think you have painted yourself into a corner. Let's consider what doesn't work ... * It is supposed to be a weapon, so a natural disaster like the gamma ray burst (otherwise an excellent suggestion) or an ice age don't work. * Cities are supposed to remain standing, so megadeaths from megaton explosions are out, too. * You excluded chemical weapons. They would not work, anyway, because there are no delivery systems to spread the stockpiles wide enough to kill 90% of mankind. (You can't just divide the worldwide production by the lethal dose. For every droplet which kills somebody, many more fall to the ground unused.) * You excluded classic biological weapons. Biologicals include biologically-produced toxins, with similar problems to chemical toxins, and plagues which could spread. * A genocidal pogrom on this scale would probably escalate to destroy the cities as people fight back. Interestingly, your question does allow genetic manipulation. So perhaps an archvillain bent on world destruction created a GM insect which is pesticide-proof and produces a toxin. After five years, the survivors are those with resistance and/or developed a new pesticide. But this explanation seems to stay within the letter of your question while dodging the intent. Next idea, in the not so distant future household robots become common enough that they can be found all over the world, not just in the industrialized countries. Of course their programming has elaborate safeguards to prevent injury to humans, but a paranoid intelligence agency installed backdoors. A hacker group detects this backdoor and decides to use it for something (ransomware?). While doing so, they disable the safeguards and order the robots to go on a rampage. The malware spreads better than expected and there are not enough bitcoins in the world to pay all the demands. Lots and lots of robots kill their masters. [Answer] Famine. You could have food become nearly impossible. Something that wipes out crops wouldn't be too hard to do since a lot of crops are very very similar genetically speaking. Massive plankton die-off. Kill the oceans and the ability for the planet to keep sustaining so much stuff starts to dwindle. It wouldn't be instant, and it wouldn't kill everything, but it could surely cut down on how many people are still around to survive it.. [Answer] If you want to kill the vast majority of people quickly without damaging most of the man made or technological infrastructure, then you are looking at a cosmic event. The most probable event would be a gamma ray burst that floods the solar system with massive amounts of gamma radiation. Since this is thought to be caused by something like the collision between two neutron stars, it is not likely to be from somewhere nearby (neutron stars have distinctive signatures in the radio spectrum, and two rapidly orbiting neutron stars spiralling inwards would be very distinct if they were somewhere in the immediate [i.e. several LY] neighbourhood). So a colossal gamma ray burst from several hundred or more LY distant would flood the solar system for hours or days, meaning the entire planet would be irradiated. Only people deep underground in mines or bunkers would survive the immediate strike, and the people on the opposite side of the planet from the burst's point of origin would have 12 hours at most to seek shelter deep underground. Even more violent cosmic catastrophes might be imagined, for example, black holes often have highly concentrated jets of energetic particles emerging from the polar regions (these are actually from the accretion disc surrounding the black hole, and not from the hole itself). If the black hole is pointed in the right direction, energetic particles moving at velocities close to the speed of light will be entering the solar system. In some ways, this might be more devastating than a gamma ray burst, since there would be all kinds of energetic reactions between the incoming particle stream, the solar wind, the Earth's atmosphere and so on. Imagine radiation, violent EMP and even the physical erosion of the Earth's atmosphere, depending on the magnitude of the incoming jet. Once again, deeply sheltered people might survive, and people on the side of the Earth facing away will have a maximum of 12hr to reach shelter. Finally, there could be some sort of technological apocalypse. The movie "The Quiet Earth" (New Zealand, 1985 <http://www.imdb.com/title/tt0089869/>) has scientists around the world accidentally trigger an apocalypse by generating a global "energy grid" (theoretically able to power aircraft in flight and ships at sea). Project Flashlight catapults the Earth into an alternate dimension, but the vast majority of the people on Earth don't come along for the ride (the lead character is one of the scientists from the Flashlight project who survives, and discovers the changes in physical constants). This answer requires a large amount of handwavium, but can be tailored to meet your exact specifications in terms of setting the stage for the story. [Answer] A new psychoactive drug is discovered. It has the euphoriant effect of cocaine but none of the downsides. It is as potent as LSD so it is impossible for the authorities to stop it being sold worldwide. Also it is popular and pretty much harmless. It becomes a global craze. "Everybody" is using it. Harmless... not. It had the side effect of triggering a protein reconfiguration in its users' brains. One similar to BSE or CJD. One dose was enough. It takes ten years to develop but is inevitably and rapidly fatal when it does. Who is left? A few adults who never indulged even once, and a generation of mostly under-tens. About 15% of the population? With a very skewed age distribution and psych profile that might help your story. Sorry ... just realized, not a weapon. Will an own goal suffice? Otherwise you will have to invoke an evil genius behind it. [Answer] Well, since Neutron Bombs and Gamma Ray bursts are already taken... # Radioactive dust. If the dust is highly radioactive, it will have a short half life. In the air, it can be breathed in, in the water, it can be drunk, and on food crops, it can be eaten. This would take a lot of dust but if it is deployed in the gulf streams, it will spread over much of the world. The 5 year to safe requirement can be met with a highly radioactive substance. Though certain areas of dust concentration might be dangerous longer. [Answer] If the story is to take place 150 years after the event, isn't the actual weapon used irrelevant to the story line and also myth to the children of the children of the grandchildren of the survivors ? Even any people on the incoming ship may not know of any weapon capable of the effects you're describing or could be familiar with several advance weapon systems that could produce the global readjustment in population count and dispersal without property damage you're describing, but unable to identify the specific one after such a long time. Sometimes leaving a backstory event where the how isn't as important to the plot as the fact it happened to the readers' imagination is better then using several pages to explain something that in the end adds little to the story. Unless the how is going to be important to your plot I'd skip that part and just work on the effects of the now unknown mega weapon. [Answer] As long as you find a way to do this on a global scale, any of these methods would work : Anything that attacks the breathing : oxygen removal, toxic gas... Here we're talking about a chemical weapon. Oxygen would reform quite fast thanks to photosynthesis. And toxic gas can be made to slowly turn into a non-lethal form. The main issue however is justifying what organisation can have the ressources and logistics to deploy such huge quantities of chemichals all around the world. "reasonable" heat : almost all non-biological materials resist to temperatures around 70-100°C. Living beings almsot certainly die. The trick is finding a way to do this in an "uniform" way to prevent having places with peaks of heat that whould affect structures or places of low temperature where people would survive. I would suggest releasing in the athmosphere huge quantities of compounds that amplify the greenhouse effect. Attacking the senses : If you can find a way to render most humans blind, I syspect an immediate high casuality rate similar to what you're aiming for (70-80% in a matter of a few weeks). Here again a chemichal agent can be used. Another way to pull this off is blinding bombs. Something similar to what's commonly called flashbang, but instead of being visible light aimed at temporarily overwhelm the eye, it would emit light in a waveband that would cause permanent damage. The trick here would be managing to get a huge percentage of the population to look at those bombs. [Answer] You become Samuel L. Jackson. Or rather, a variation of one of his characters. In the 2014 film Kingsman: Secret Service, > > the main villain - Valentine - designs a SIM card which he gives for > free to as many people he can over the world. > > > Essentially he created a product/service that everyone uses and wants to keep using, except without any costs for the user (almost guaranteeing that people would adhere to it). However, it had a catch, the cards were able to make people become uncontrollably violent, which would make people try to kill everyone around them [(Hopefully while Freebird is playing in the background)](https://www.youtube.com/watch?v=NXB6slJSbL4). This is the perfect method because you can virtually get to decide who is affected or not. This could however be prejudicial to buildings, and as such you wouldn't design the SIM Card (or any other device that could "change minds") to turn people into Agressive Primates (because they could just as well destroy a building in their fights). Instead you'd make them suicidal. By making them suicidal not only you can control exactly how many people will die, but you also assure that they're not even going to destroy anything else with them. They'll just... die. [Answer] I concur with @Gawainuk in that this event is a backstory event with little real relevance. You could handwave it as > > It was a freak cosmic accident, that had even been foreseen more than once. They had thought of cosmic poison cloud swamping the Earth1, or [noxious gases being spewed out by volcanoes in a purple cloud suffocating the planet](https://en.wikipedia.org/wiki/The_Purple_Cloud). > In the end, the gas did come from space, but it was colorless, odorless and not even directly toxic; the only warning it gave was a [sudden lowering of one's voice](https://www.youtube.com/watch?v=A7XdOyZIkko&feature=youtu.be&t=69). But it was markedly heavier than air, and in a few breaths all the oxygen would bubble upwards, out of the victim's lungs. The winds in the stratosphere had already diffused the gas over the whole world when the first traces reached ground level. Very soon, [large invisible clouds](https://en.wikipedia.org/wiki/Lake_Nyos_disaster) rolled down over mountains and hills, flowing downward and finally reaching the sea; most areas were not affected for more than a few hours. But for too many people, those few hours were enough; those caught in the open only had minutes. > Over half the human population died in the first forty-eight hours together with most cattle and all internal combustion engines. The survivors came out of cellars, landed from the surviving planes, discarded their emergency oxygen bottles and makeshift rebreather kits, and found themselves facing a civilization largely ground to a halt and four billion corpses. Five years later, another two billion people had succumbed to famine, sickness, despair and violence, and the lowlands nearer the seas remained uninhabitable and lethally dangerous for more than fifty years. > > > (1) This is Robert F. Young's The Rachel Carson Effect, which I believe might have been published in The Worlds of Rober F. Young. (Okay, no. There is no known mechanism that would lead to the formation of so much sulphur hexafluoride in space, and it would not be a cloud - it would be a frozen solid, burning in the atmosphere just as an ice meteor would). [Answer] Entertainment. Something new, irresistible and addictive well beyond our current smartphones. People just neglect their lives, stop showing up at their jobs. In some cases, they starve with food still in the fridge, too engaged to bother eating. When governments begin taking action, too many devices have been distributed. People will flee, hide, and fight tooth and nail to keep their fix. Civilization collapses. The devices are now impossible to produce, maintain, or even recharge. Many still die from accumulated neglect. Quite a few commit suicide. But many others recover gradually over weeks, and quite a few never used it in the first place. ]
[Question] [ Lets pretend that Mars was a bit larger, so the gravity could hold on to the water and possible atmosphere, and then play along with the accidents that happened on earth happened at a similar tact. Somewhere between when the telescopes appears and now we gaze at mars and see people just as us looking back. What changes and impacts on space-faring would that make? The drive to meet those other people there. EDIT: Removed irrelevant information. [Answer] First of all it would eliminate the question whether or not we are alone in space. Although, even with a very similar setup it is highly unlikely that two completely isolated species evolved [in a similar time frame](https://en.wikipedia.org/wiki/Fermi_paradox) to similar extents of intelligence and such. But ignoring that point: if in your setup this has happened, i think we (or they) would by now have built ships to go to mars. And long before that we will have tried to communicate with the Martians. We might have used something as simple as Morse signs with a big enough lamp. I guess, if we do not take into account the possibility of sharing technologies via Morse code (or other communications technology), right after the moon missions the building of a mars going ship would have started, in even a bigger space race than the early cold war times brought forth, since prestige and potential profit from being the first to meet the Martians in person would have been huge. Since all doubt of achieving anything "useful" would thus have been eliminated, it would have been almost trivial to convince the general public to cough up the tax money for that project. Finally, the prospect of profit would most likely result in a higher risk tolerance than we encounter for current mars projects, which should again result in speeding up the projects. [Answer] Ok, I'll play, but I will also list a few reasons why this would be a wildly unlikely scenario at the end. --- ### Sister-Mars scenario So, we have two sapient species, with early modern tech, finally able to see each other. With Human-level 17th century tech (first telescopes were developed in the early 1600s), you'd be able to get 30x magnification and see Sister-Mars as if it were the size of a grain of rice. I'll look at it from the Earth-centric perspective. [Look at this image from 10 feet (3 meters) away](http://oneminuteastronomer.com/5352/observe-mars-telescope/) to get a sense of what early astronomers would see. ![Mars](https://i.stack.imgur.com/wg7Xx.jpg) Of course, since Sister-Mars is double the radius of actual Mars, it would be double the size. Needless to say, you would not be seeing cities, or even mountains. However, you would see a blue and white jewel sitting in the dark sky. Thus, the existence of oceans and ice-caps might be quite easily resolved. Galileo's first book, the [Sidereus Nuncius](http://en.wikipedia.org/wiki/Sidereus_Nuncius), would likely be about Sister-Mars and its oceans rather than [Jupiter's moons](http://en.wikipedia.org/wiki/Galilean_moons). Oceans! On Mars! 20 editions would burn off the printing presses before the year is out. An enthusiastic [Prince Maurits of the Netherlands](http://en.wikipedia.org/wiki/Maurice,_Prince_of_Orange) offers a 2000 florins prize for an improved glass for the new farseeing telescopes, triggering an optics revolution. A [jewish glassmaker in Amsterdam](http://www.hebrewhistory.info/factpapers/fp005_robles.htm) claims the prize, and mountains and vegetation cycles are soon noted for Sister-Mars. A Spanish writer publishes a best-seller by the name of "The Ingenious Gentleman [Don Quixote of La Mancha](http://en.wikipedia.org/wiki/Don_Quixote) on Mars", where he depicts the hidalgo getting caught up in air vortices and dragged to Mars. By the end of the 17th century giant 300x telescopes are being built, and a thriving literary genre imagines various utopias and dystopias on Mars, inspiring generations of young budding scientists to dream the impossible. Disastrous attempts to launch projectiles "toward Mars" are conducted over and over again. The intense attention to astronomy, and the craze among the nobility about court astronomers results in the laws of celestial mechanics being discovered a century early, triggering an early scientific revolution in Europe. A Dutch lensmaker by the name of [Baruch Spinoza](http://en.wikipedia.org/wiki/Baruch_Spinoza) invents what we know as the [Tsiolkovsky Rocket Equation](http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation), but means of propulsion into orbit remain beyond the era's technology. A young [Isaac Newton](http://en.wikipedia.org/wiki/Isaac_Newton#Optics) invents calculus and focuses on optics in an attempt to improve telescope resolution, discovering spectral lines in the process. [Blaise Pascal](http://en.wikipedia.org/wiki/Blaise_Pascal) devises means of calculating atmospheric interference with the telescopes, discovering many of the gas laws and pertinent information about atmospheric composition in the process, including many [useful properties of steam](http://en.wikipedia.org/wiki/Steam_engine). Railway lines crisscross Europe by the mid-1700s, and a full blown industrial revolution is soon underway. By the early 1800s, Prussian artillery is finely crafted enough to launch projectiles on suborbital paths. Radio is discovered, and within 30 years, anomalous signals are detected coming from Mars. [Carl August von Steinheil](http://en.wikipedia.org/wiki/Carl_August_von_Steinheil) is the first to realize these were the product of another civilization. --- ### Caveat: Why such a scenario is highly unlikely The process of evolution works by selecting on the results of random variation from established forms, whereby the phenotype is exposed to the particulars of a time-space environment and successful reproduction in that environment allows the perpetuation of the genes in that genotype, even though the individual organism is generally not repeated. Reproductive success is therefore the product of numerous random mutagenic factors, as well as subject to exogenous shocks such as equilibrium-altering events (invasive species, climate fluctuations, massive ice ages, continent-wide volcanic eruptions and even massive space-origin impacts such as the one that is assumed to have killed off the dinosaurs). Now imagine you have the extraordinary fortune to have not one but two Gigayear-habitable goldilocks-range worlds in the same system. By the established mechanism of asteroid exchange, life would most likely successfully spread to both worlds. So far so good. But from here on, life is set to diverge wildly. Even if the two worlds are similar as raindrops, there's a good chance you'll end up with trilobites or dinosaurs dominating on one world and mammals on another, since as far as we understand, many of the extinction events drastically altered global ecosystem balance, by literally wiping out the competition. The situation you describe would indeed be every xenobiologist's fantasy: how much convergent evolution does take place, and how much is dictated by random factors? Were dinosaurs doomed by their tiny brains, or would mammals have forever been stuck at the terrified night rodent stage if not for the Chicxulub event? Ask yourself: What are the odds of two essentially independent planets happening to develop intelligent life at exactly the same time? Moreover, since humanity spent its first 100,000 years as hunter-gatherers, what are the odds the two independent sentient species would then proceed to develop agriculture at the same time? Yet more coincidentally, they also develop the scientific method within decades of each other. Far more likely that one would reach space tech while the other world has no sapiens-level intelligent life at all, or at the very least, while the other is stuck in its long hunter-gatherer dawn of civilization stage. This can all be waved away with sufficient amounts of alien-ex-machina, who choose to come back every few million years and direct the evolution of life on both worlds, even transplanting individual genes, or perhaps full genotypes or phenotypes (that further their incredibly long term plans) from one world to the other. So I'll go ahead and assume that happened. --- If you want to know more, you could to worse than to readi about the [Drake Equation](http://en.wikipedia.org/wiki/Drake_equation). [Answer] This reminds me of a series of short stories I read some years back where the premise was that interstellar space travel (FTL, via some kind of unexplained space warp) was incredibly easy, and that somehow Earthling technology just missed it, and went on to get to the cusp of interstellar travel the hard way, by actually flying through the intervening space. As a result, humans eventually burst onto the scene of a community of traveling, trading sentients like the proverbial bats out of hell, with technology far more advanced than any other species. Most species (and this is why I was reminded of it,) were somewhere around the early Industrial Revolution, up until the late Victorian; so it was 21st century Earthling mech against aliens with steampunk tech. The prequel to the series was [The Road Not Taken](https://en.wikipedia.org/wiki/The_Road_Not_Taken_%28short_story%29 "The Road Not Taken on Wikipedia") by Harry Turtledove, and I'm pretty sure the collection was Herbig Haro. The same author also wrote [A World of Difference](https://en.wikipedia.org/wiki/A_World_of_Difference_(novel) "A World of Difference on WIkipedia") which changes Mars to be the same size as Earth, and proceeds from there.... It sounds like you're driving at something similar, wanting to know what's the minimal level technology we'd need to start up interplanetary intercourse with our "sister planet." So here are some alternatives: * The age of Wooden Ships and Iron Men Let's assume that sailing was the paradigm, and that solar sails could be made.\* Well, few people realize that already in the 18th century submersible vessels were being built ... of wood! For example, [The Turtle](http://en.wikipedia.org/wiki/Turtle_(submersible) "The Turtle on Wikipedia") was an American submersible built to sink British warships at the beginning of the American Revolutionary War. (1776 - It worked as a submarine, but it failed to attach a mine that actually detonated a warship.) The point is that similar technology could probably allow construction of solar sails that would spend months traveling the interplanetary void between Earth and Mars. And don't worry about them breathing - Antoine Lavoisier was synthesizing oxygen two years before the Turtle sailed in New York harbor. The problem is that getting up to space, and back down again is a darn sight trickier than traveling in space. The [Robert brothers](http://en.wikipedia.org/wiki/Robert_brothers "Les Frères Robert on Wikipedia") show you how to get part way there -- they built the first hydrogen balloon in 1783. And within two decades William Congreve was improving on Indian rocket technology for the British. With a visible impetus during the preceding centuries to travel to Mars, I think it is not an unreasonable stretch to describe interplanetary sailing ships of combined wood and metal attempting the voyage by the mid 19th century, just as steam power and the Industrial Revolution are taking off. Hydrogen balloons would raise the people and goods to a certain height, and from there rockets would carry them the rest of the way to "floating docks" or "levitated islands" (space stations) from which they would embark on a solar sail journey to the other planet. I mean, I for one would willingly suspend my disbelief to a bit of plausible writing in an alternate history scenario like that. \* The big problem with making solar sails is making a thin enough, reflective enough fabric. Postulate an industry using [spider silk to make the sails](http://en.wikipedia.org/wiki/Golden_silk_orb-weaver#Golden_silk "Image of spider-silk fabric in Wikipedia article") that developed a couple of centuries earlier. * Steam Power (Sorry I haven't finished this yet.) [Answer] Since you've ruled the timeline to be irrelevant lets say the discovery happens around the late 19th century. Italian astronomer Giovanni Schiaparelli observed Mars in 1877 and described straight lines he called canali (sometimes translated as channels) on mars. Canal travel was huge at the time so this was taken as a sign of intelligent life like our own. So in this scenario, instead of being proven wrong, he's eventually proven right. Albeit for the wrong reasons but that happens in science more than you might expect. It took a fair amount of time to prove him wrong (some people still believe) but if you want to know what would happen if we thought there was life on mars, go back and read what did happen when many believed. [Answer] I think that jumping from the 13th - 16th century to space flight is a bit too broad, because in the middle several things might've gone differently. For instance: Ever since the beginning of time, we've attributed the things we don't know how to explain to gods, so what if once we notice the martians, we take them to be those gods? Then we (or at least a portion of the humans) would've grown to think of the martians as our gods, there would even be full blown riots from "martian worshippers" against the (unworthy) men of science trying to communicate with them. A sort of a holy war against scientists who claimed that "the gods from above are mere mortals like us". Who knows, maybe space-related technology is eventually pushed back because of the power of those fanatics (which in this scenario would have proof that their gods are real, thus gaining far more adepts) I'd like to think that eventually science men would prevail, but history would probably be very different and technology would take longer to develop because of the false belief on the martian gods. Addendum I want to also add what would happen once we do realize that the martians are just "people": After that happens, all efforts would probably go into establishing a stable channel of communication, even before thinking about travelling there. And depending on their intentions (let's assume they're nice guys), our tech and knowledge would improve exponentially, just like theirs, since both civilizations would start sharing information and knowledge . ]
[Question] [ I have an idea for a magic system where the one wielding magical power can shut off gravity for their body. However, anything on them (clothes, accessories, etc.) will still experience regular gravity. I am having a hard time conceptualizing how this power will play out in the world. To keep it simple and hopefully get more directed help I was trying to imagine what would happen in two different scenarios: 1. What would happen if a magic user launched themselves in a catapult? Would gravity pulling on their clothes lead to a nice arc, or would they gain too much speed and splat. 2. What would happen if they were to jump straight up or at an angle? Would their momentum carry them before gravity's effect on their clothes asserted itself, and would they then pick up speed as they head back to the ground? [Answer] It would basically be like being on a low-gravity planet or moon. Under normal gravity, all objects fall with identical acceleration. Heavier objects feel a larger gravitational force than light ones, but they also have more inertia to overcome. This balances out perfectly and leaves all objects with an acceleration of 1g, regardless of weight. If the person has zero weight but their clothes do, they have essentially reduced their gravitational mass but not their inertial mass - gravity pulls down on them with the strength it pulls on perhaps a 2kg object, but that force still needs to accelerate a 70kg person. The overall result is that this person does not experience as much gravitational force as they "should" given their weight. The person exists somewhere between zero-gravity and full-gravity, commensurate with what fraction of their overall weight is made up of clothing. They'd fly higher/further if launched by a catapult, and have a greater vertical leap and hang time when jumping. If they got naked, they'd enjoy zero gravity. If they donned a huge suit of lead armor, shutting off gravity to the body would have little overall effect. For a typical person and outfit, clothing is <5% of the body weight, making this person experience even less than the equivalent of Pluto's gravity when shutting off their body's gravity. Even though the force holding them down is very weak, it's still more than enough to keep them from being flung from the planet due to rotational inertia. [Answer] The first thing you'd want to consider is centrifugal force. If gravity isn't holding you to the ground, then the rotation of the earth would throw you off. The centrifugal force is roughly 1% of your weight, so if you were on the equator and you weighed 200lbs, you'd need to wear at least 2 lbs worth of clothing to stay on the ground. A weird bit would be that, if you aren't at the equator, the centrifugal pull would pull you at an angle, so even with clothing, you'd have to lean against it to keep from being pulled towards the equator. When falling from a great height, your terminal velocity would be a lot lower. Put your clothing on a cardboard cut-out and drop it off of the roof to see how much. You would be able to control how you fluttered around the same way sky-divers do, but you'd need to manage your wardrobe if you didn't want to fall feet-first. update: Nuclear Hogie pointed out that the force of gravity on your clothing would be divided into your mass plus the clothing's mass. This is hugely important, because it means that the overall effect would be equivalent to around 1% of normal gravity. Even wearing full field plate armor, you'd be experiencing 1/3rd gravity. If gravity pulling on your clothing alone were analogous to pushing a person, gravity on your clothing pulling on your whole body would be analogous to pushing a person in a car. This supports his low-gravity hypothesis. 2nd update: John pointed out buoyancy, which, at sea level, would (very) roughly be equal to your weight divided by 773, or between 1/8th to 1/7th that of centrifugal force. Thanks, John! When being launched, wind resistance would be fighting against your mass, not your weight. You'd still slow down due to wind resistance, but I suspect that a pumpkin chunkin' trebuchet could throw you miles away. If your clothing wasn't adequate to counter centrifugal force, you would never come down. It occurs to me that, if you could come up with a squirrel suit that weighed less than the centrifugal weight offset, you could turn the power on to get altitude, then turn it off and use the squirrel suit to get some velocity. Oh, as a final point, if you wore light-weight wings (and were reasonably fit), you could definitely fly, but slowly. [Answer] Gravity is what keeps everybody and everything existing on Earth on the planet. Without gravity, each body, conforming to Newton's First Law, would continue in a straight line until a force acted on it. This means that if your person is naked while activating their power, they would immediately fly off along a tangent to Earth's surface at the same velocity of the surface in that moment. This means they would slowly drift up, while the rest of the planet would keep revolving around its center. The above would be true for a short time, but then also the motion around the Sun would start to become noticeable, and later on also the motion around the center of the Galaxy. By that point, however, the person would be already dead of suffocation due to the exposure to the vacuum of space. If instead the person wore clothes, as stated by Nuclear Hoagie, they would get a little weight from their clothes and would manage to avoid death. [Answer] You might need to tie a rope to the poor mage > > What would happen if a magic user launched themselves in a catapult? Would gravities pulling on their clothes lead to a nice arc, or would they gain too much speed and splat. > > > I made an error with the first version of my answer. The mage still has mass, but not weight. The last thing, the very last thing that you want to do, is put that poor mage into a catapult. Why? There's no longer an escape velocity other than the force needed to overcome air resistance. Without the mass of the mage, all that's holding that poor devil to the ground is the weight of his/her clothes. The energy needed to move a couple of pounds of clothes to escape velocity is a LOT lower than what would be needed to move the entire mage. Now, honestly, no, a catapult can't put the mage into orbit. ("Blue. No, yelloAAAAAAAAAGHHHHHH!") The clothing would need to reach 11 km/s and a quick Google search indicates the best "muzzle" speed of a trebuchet (so much better than a catapult...) is only 0.45km/s. But, still, the poor schmuck might need to care about the mountain range in the distance. ...With the exception of air resistance, which will slow him down. Eventually. BTW: Considering the popularity of extreme sports like bungee jumping, I'm a bit surprised that someone hasn't put an electronically-controlled parachute on someone and launched them out of a trebuchet. Honestly, I'd bet people would line up to hand you $100 to be thrown from a trebuchet. GPS-enabled electronics to release first streamers to slow the ~~victim~~ participant followed by the release of the parachute. If anybody does it, I thought of it first. You owe me dinner and movie for two. Muscles... on the other hand... > > What would happen if they were to jump straight up or at an angle? Would their momentum carry them before [gravity's] effects on their clothes asserted itself, and would they then pick up speed as they head back to the ground? > > > This is a different matter because we're dealing with much less energy than a catapult. The body's muscles, which have grown accustomed to the weight of the body. Take away that weight, and the muscles can do a lot more work! Think about it this way: you get a job moving 50# bags of cement all day. After 3-4 months of work (and a lot of sore muscles), the job gets easier. Your body's muscles have grown accustomed to moving your weight plus the weight of the cement. You might not have noticed, but it's actually easier to move yourself around the dance floor at night thanks to the stronger muscles. The situation is the same. Rather than not moving 50# bags of cement, you're not moving, let's say, 200# worth of person. But that person's muscles are conditioned to moving 200# worth of person! You bet, you'd be able to proverbially (and, to a degree, realistically) leap those tall buildings in a single bound! This concept was adopted by Edgar Rice Burroughs for his Barsoom series of books. John Carter, having grown up on Earth, found himself on the much weaker gravity of Mars. At the time of writing, neither authors nor the public knew Mars' gravity was weaker, but didn't really understand what that meant. So no one blinked twice when John Carter was able to leap 50-100 feet into the air.... Of course he could! Muscles conditioned to 1G were suddenly in 1/3 the gravity. How high could the mage jump? We can use the following equation if we know how high the mage could jump before the spell. $$\text{Height}\_\text{peak} = \frac{1}{2} \left(\frac{\text{velocity}\_\text{takeoff}^2}{9.81}\right)$$ Use the equation the first time to solve for velocitytakeoff, then use it a second time.... Here's where things get a bit tricky. You see, we're cheating in that the number 9.81 reflects the acceleration of Earth's gravity. I'll leave it up to the user to reverse engineer this to deal with mass (e.g., the original mass of the mage + the mass of the clothes, then solving for just the mass of the clothes). Instead, we can get a rough estimate of how wonderful this spell is by simply changing 9.81... to 1.0. That's basically 10X the jump height — and you can rationalize more simply because that's a very, very conservative simplification. That all seems a bit counter-intuitive I know. The catapult is putting the same energy into throwing a rock and throwing the weightless mage. Logic would say that the mage would travel further. In a vacuum, that would be true, but over the distance a catapulted rock is intended to travel and the speed that's involved, air resistance becomes a big deal! Compared to the shorter span and lower energy push of muscles, air resistance has a much lower effect on the result. That's why the mage can jump further, but would have trouble with catapults. [Answer] Plenty of good answers already, I'll just add a bit more intuition to the mix. You can imagine your weightless wizard like an air balloon, filled with air and a little bit of helium. A normal air balloon is slightly heavier than air; in your case you want it to be slightly lighter than air (as if it was filled with vacuum), so - a balloon which is slightly lighter than air and rises slowly up. Well, when naked anyway. Clothing would keep them grounded. [Answer] # You need a lever, not an on/off toggle Sure, maybe the apprentices can only change their gravity full-blast, but surely experienced mages are able to subtly shift their interactions with gravity? That would give you more wiggle room to get a variety of effects. More directly to your question, though, you can basically think of the described scenario as if the mage only weighs as much as his clothing and accessories. His body is still subject to drag, though, making him like a kite or parachute- Lots of surface area, relatively little mass. #### Flight Scenarios Throwing a kite or parachute from a catapult wouldn't go very far. Turning gravity down or off on a person already flying through the air would cause them to speed up proportionally, to follow the law of conservation of momentum. (Their top speed would be limited by drag, as that [increases exponentially with velocity](https://www.wolframalpha.com/input?i=drag%20force&assumption=%7B%22C%22%2C%20%22drag%20force%22%7D%20-%3E%20%7B%22Formula%22%7D).) Becoming heavier again mid-flight would cause them to slow to beneath their initial speed, as some momentum was lost earlier due to the increased drag. I'm reminded of the main character from Brandon Sanderson's Mistborn, Era 2, who can "store" some/all of his weight, weighing less for a time, then draw upon that store to weigh as much as a freight train at a later time. [Answer] Let it solve as a physic puzzle here: * For the mage himself, we have 2 mass, him and his belongings. * The magic spell removed the force of gravity for him, but not his acceleration Then: We can compute: $m\_{belongings} \* g = [m\_{belongings} + m\_{mage}] \* acceleration$ The acceleration on the mage will then be: $acceleration = \frac{m\_{belongings}}{m\_{belongings} + m\_{mage}} \* g$ What it means is that the mage will simply act as if his acceleration is divided by the ratio of his belongings and his own mass (considering his belongings are an order of magnitude lighter than him). If he was naked, his acceleration would be zero (he will continue to travel at the same speed as he was before until he hits something). This would mean that if he pushed on something (like jumping), he won't stop until the air resistance would cancel his speed (which might take a huge time at slow speed). He won't be called back to the ground (until it rains a lot) As soon as he has some belonging, the same movement will act like in a linear combination of how the belonging would proceed and what I described above. The heavier the belonging, the closer to the usual behavior. Some note here: Even if he jumped with all his strength, and appears to fly. If he hits something, he will hit with his actual speed and mass. His speed might be low (due to low acceleration), but his mass is not changed, so his moment of inertia ($mass \* velocity$) is still high. Its a bit like if you were hit by a lead ball and a plastic ping pong ball of the same volume going at the same speed. The effect of the lead ball will be a lot more painful than the ping pong ball. ## To answer the catapult question: The catapult transfers/converts mechanical energy to kinetic energy. An ideal catapult would thus give all its mechanical energy to the bullet. Since the kinetic energy isn't dependent on the acceleration and thus, the force of gravity, the effect on the mage would be the same as if he was subject to gravity (he would get the same speed with or without the spell). As soon as he's ejected from the catapult, you are back to the first law of Newton, except that this time, you've to account for another additional force, the air resistance (called drag force) which is proportional to the surface area of the mage and his speed (and not his mass). This term will append on the force of gravity of the belonging too. It would slow down the mage's speed as fast as if he was submitted to gravity, but his parabola back to the ground will be a lot longer since it would be like if only the belongings were catapulted, with a parachute the size of the mage. To give a nice example, he would behave like a badminton's shuttlecock, until he hits the ground. When he does, he'd create the same crater as a 100kg lead ball coming at the same speed. [Answer] I'm reminded of "The Billiard Ball" by Asimov, where the twist was that any object which was completely isolated from gravity perforce moved at lightspeed. The problem I have is: if isolated from all external influences, in what direction would it move? ]
[Question] [ Werewolves exist in organised societies hidden from humanity at large and over the course of their history they had certain lycanthropy-related problems to overcome. While their condition comes with perks, it also has downsides. In particular in terms of medicine, werewolves are immune to most diseases and poisons and they have a very high healing factor - that is to say their wounds and injuries heal very rapidly. Sounds awesome at first, but it comes with its own set of problems. Healing factor Werewolf healing has its limitations. The following mostly pertains to their human form, as in beast form their healing factor goes into overdrive but the same principles remain. As far as speed of healing is concerned, it depends on the size of the wound as well as general condition of the werewolf. For example, a gunshot wound will take a few minutes to heal, but having multiple gunshot wounds will slow this process down (healing will be spread equally, a second injury will slow down the healing of the first injury and so forth) Additionally there are limitations to what can be healed. For example: * A severed limb will not regrow, but the wound itself will close. * A bullet wound will heal but the bullet - if stuck inside - will remain inside rather than be pushed out. * A broken bone will mend, but if dislocated, it will not be pulled into its correct position on its own What this means is that despite the awesome healing potential, there are still situations when doctors and surgery are needed - for example an othopedic surgery to break improperly healed bones and set them back into place or a surgery to remove bullet or shrapnel from inside the body. And this is where my problem lies. How to operate on a rapidly-healing werewolf? Any incision made during the surgery will quite literally start to heal before the surgeon's eyes. Unless the entire surgery lasts no more than a few minutes, that's a problem. Additionally, the side effect of being immune to poisons also renders werewolves virtually immune to anesthesia and sedation, which means surgery will need to be done on a conscious and feeling patient. As pain is transformation-inducing, this also means operating is only possible in daytime, so any multi-hour surgeries become an even greater problem. With some additional assumptions: * Modern medicine (2010s-2020s) * Surgery will be performed by a trained team of medical proffessionals who are aware they're operating on a werewolf The question is: How to perform surgery on a rapidly healing werewolf with greatest chance of success and minimal harm/discomfort\* to the patient? \I'm not expecting the patient to be comfortable during a no-anesthesia orthopedic surgery, all I'm saying is "no needless torture". Emphasis on needless. If any data is missing let me know in the comments and I'll do my best to provide missing information. Info added in response to comments: Can werewolves heal from nerve damage? - For the most part yes. If the nerve is severed or torn then yes. If the nerve is severed and then a large portion of it is removed from the body then it's a bit more tricky and full recovery may not be possible depending on how much of original tissue is missing. How is the werewolf regeneration spread out? - There is indeed a "healing per time budget", which is spread equally among all the wounds. There is no mechanism for prioritisation, all wounds heal simultaneously, but the more wounds there are, the slower the process is. There comes a point where the werewolf would be wounded enough that the healing process can't keep up with blood loss, which could be called the leading cause of werewolf mortality. [Answer] Not all anesthetic options are poisons. You can induce a loss of consciousness by restricting blood flow to the brain, by restricting oxygen in their available atmosphere or replacing the oxygen with something else. Nitrous Oxide has been used as a dental anesthetic for centuries (since 1793 in fact), induces numbness throughout the body and a sense of euphoria. Unless your weres have a radically different neural biochemistry than humans, nitrous will at the very least reduce the discomfort. In higher concentrations it can cause loss of consciousness, and brain damage or death can occur if there isn't sufficient oxygen in the mix... so make sure it's carefully administered. For spot anesthesia I recommend a return to the classics: ice. When you chill flesh the capillaries contract, restricting blood flow to the area and incidentally starving the sensory nerves. That's why you can't feel things very well with cold fingers. Go too far or leave it too long however and the lack of oxygen to the tissues results in tissue death, so this one is for short operations only. We're not trying to kill the patient with localized frost-bite after all. Now that we have the patient sufficiently docile and numbed up, let's look at the surgical problems of the healing factor. In modern surgical procedures - at least the ones that aren't done through keyhole surgery - it's standard procedure to hold the surgical wound open with the use of retractors. Here are some examples (via Google Images): [![Surgical Retractors](https://i.stack.imgur.com/hfkgk.jpg)](https://i.stack.imgur.com/hfkgk.jpg) (Trust me, this is a rabbit hole filled with torture instruments. Investigate at your own risk.) Retractors keep the surgical wound open so that you can muck around inside without having to constantly fight the skin's natural tendency to close up. The same principle can be applied to a regenerating body with a few minor modifications. Let's use wider more solid contact surfaces. Instead of those little loops and pins, let's put big plates on there so that the flesh doesn't just grow around the retractor. For classical werewolves we may be able to use an alloy with a tiny bit of silver in it, just enough to inhibit the regeneration without causing the flesh to burst into flame or something. We're trying to save their lives, not slay them. Once the wound has been open for long enough, the body will heal the cut surfaces and start grown skin over it just like an amputation. That's a good thing for our purposes since the new skin will help protect the incision site. At that point we can remove the barriers and use our normal retractors to keep the healed surfaces spread open, but most of the bleeding will have stopped. Our support team can then focus less on wound management (suction and gauze application to clear blood and other fluids from the surgical site) and more on trimming regrowth from the site itself. Your support team will need special training in managing regeneration during surgery, so it'll need a couple of specialists for this part. Once you're done with the surgery the normal closing stage, with sutures and so on, is replaced with a quick removal of the new skin in the incision. The edges of the incision can then be positioned and immobilized to allow them to heal properly. On the upside, surgery on a werewolf is a sprint, not a marathon. Extreme regenerative abilities means you can skip over a whole bunch of the things that you have to do to keep a strictly human patient alive. After all werewolves can live through some pretty crazy stuff. You don't have to be slow and gentle with these guys, just get in there and get the job done as quick as possible so that they can be shipped off to recovery. Just about any surgery is day surgery when you heal like they do. Depending on how the were transformation works, and what effects it has on existing wounds, it might be best if you can induce a transformation shortly after surgery. Some stories about weres have them healing non-critical wounds during their transformations, either to or from were form, maybe both. Hospitals dealing with lots of werewolf surgery might have recovery rooms that simulate moonlight or channel stored moonlight or something to facilitate brief changes. You decide what works for you here. --- As fun - and occasionally nauseating - as it is to speculate about how actually you'd do this, it's sometimes just as if not more interesting to speculate on how the various techniques were developed. Does your world have a history of brutal experimentation done on werewolf prisoners? Was some version of Josef Mengele cutting open Jewish werewolves (is that even a thing?) at Auschwitz? And he's just the best known (and most reviled) example that comes to mind. On the other hand, was there some version of Joseph Lister discovering a regeneration-inhibiting formula to enable proper surgery for werewolves? Did William Morton go on to find a substitue for ether that worked for weres? So much back story, so little time. [Answer] Victorian style: fast!* Before anaesthesia, speed was of the essence. In creatures immune to anaesthesia fast surgery is still welcome. For your fast healing werewolves speed serves double duty - it gets the surgery done before the wound can close. <https://www.bbc.com/future/article/20200624-how-agonising-surgery-paved-the-way-for-anaesthetics> > > From first cut to severed limb dropping into a box of bloodied sawdust, > surgeon Robert Liston could remove a leg in 25 seconds. His operations > at University College Hospital in central London in the early 1840s > were notorious for their speed, intensity and success. The chance of > dying from a Liston amputation was around one in six – much better > than the average Victorian surgeon. > > > The speed of the procedure had its advantages. With no pain-relief > available, it shortened the almost unimaginably horrific trauma of > surgery. The screaming patient would typically be held down on a > wooden bench by "dressers", who would also assist with ligatures, > knives and dressings. > > > Fellow werewolves will serve as dressers. They are at less risk from getting nicked or cut by fast flying knives because they are werewolves. [Answer] The Wound-Healing Process Phases of normal wound-healing Process * Hemostasis * Inflammation * Proliferation * Remodeling Slowing the wound healing process [Following factors](https://www.byramhealthcare.com/blogs/8-factors-that-affect-wound-healing) slow the wound healing process: * Skin Moisture: In order for wounds to heal properly, they need a certain degree of moisture and fluid. Dry wounds can cause lesions, are more susceptible to infection, and causes elongated healing times. * Chronic Conditions: People with cardiovascular conditions or diabetes are at the highest risk of slow wound healing. * Tissue hypoxia: If there is a limited supply of oxygen to the wound, it prevents the production of collagen, causing slow wound healing. * Medication: Anti-inflammatory drugs as aspirin and ibuprofen, can interfere with the inflammation stage of the healing process. Anticoagulants have the capacity to disrupt blood clotting, while immunosuppressants may weaken the immune system and enhance the risk of infection. Conclusion Inject some anti-inflammatory or anticoagulant or any special drug which will slow down the healing process by limiting the supply of oxygen to the wound or preventing the production of collagen. Make sure that the effect of the drug will go away after the operation is over. [Answer] Freeze them first. Inject with a natural antifreeze chemical, Glycerol for instance. Thaw the local regen to be operated on and cut away! Sever spinal cord induce paralysis. Repeat for duration necessary. Alternatively severing major nerve branches, Cervical nerves, Thoracic, Lumbar, Sacral, or coccygeal nerves, for the duration of the surgery. [Answer] # Silver Use a silver scalpel. They won't be regenerating that cut so fast. As for anesthesia, lace it with silver too. There are plenty of medicines made with it, it is mostly non-toxic. Since it won't be making any wounds but rather keep the healing factor it bay it shouldn't be (too much) lethal. Might help opening up the patient too. [Answer] # Cut the spinal cord and new medicine Leas amount of discomfort is actually easy. All we have to do is cut it! It isn't easy to cut it, but my guess is that a werewolf community will eventually invent easy ways and tools to sever the spinal cord and keep it severed. Either by blocking or keep severing it. The advantage? No pain or discomfort past the point of incision. With special tools like laparoscopy and the right area you can make the point of intrusion to cut the spinal cord as comfortable as possible. ## new surgery Although the above gives you time to work you still can use new medicine to make it easy. As mentioned we can use laparoscopy. It is basically a flexible tube that can be moved through the body. Often blood vessels are used to move from an easily accessible area, like blood vessels in the leg, to difficult to reach areas. As the tube is like a bullet the flesh can't throw it out. This way we can get to bullets if we want. ## speed On the other hand, do we need special tools? The patient doesn't feel it anyway. Cut them open quickly, remove the bullet and get out. Break bones and set them. Maybe even remove a whole bone if this grows back. With high speed you have little problem of things growing back before you've accomplished your task. It is also most comfortable for the patient. A quick rend of flesh when they don't feel it. It'll heal in a few minutes and you're done. More complex situations need more time, but the body willl give it by adding more damage. This way we can keep someone from feeling pain below a certain point while doing all the required surgery and having nothing close on us prematurely. ]
[Question] [ Witches exist at all levels of society, including the top echelons. These individuals summon the orgone within themselves to perform various feats of magic through invocations. One brand of magic revolves around battle. These attacks can be very powerful, and consist of magical attacks and defenses. Some are designed to focus on a particular opponent, such as fireballs and beams of energy. Others are geared toward an entire area, such as lightning storms or small tornadoes, which can kill dozens if not hundreds of people. Still others focus completely on defending the user, such as magically generated shields or protective spells. Battle magic is powerful, and can turn the tide in war. However, they have some limitations which can effect their success. 1. Invocations can last anywhere from 30 seconds to 5 minutes depending on the type and Power of the attack. They last for various durations. Some can be used repeatedly with the mage keeping the spell active by using a shorter version of the incantation (energy blasts, fireballs, etc). Others are one-shots, and the mage must start over from the beginning to use a second time. 2. Battle magic requires a certain amount of orgone from the witch. The cost is determined by the power or length of the spell. Orgone replenishes over time at different rates depending on the user. 3. Mages must be relatively close to the area they wish to target. They can be separated only by a few dozen feet in order to be in range, or the attack won't hit. Basically, witches can be walking, fleshy tanks, and are very valuable to their societies. However, they can also be targets for assassination or sabotage by other rival covens or states. Therefore, they are often heavily protected by shield guards. The job of these guards is to keep their witch alive, and protect them while they are performing their invocations. They can range from one to several, depending on the importance and wealth of the witch. It would be common sense for witches to use other witches to guard them, as one can focus on defense while the other on attacks. This would provide for an impenetrable combination. However, shield guards are always magic less. Instead, they use regular weapons to protect their wards. Why would witches not use lower-tier witches to defend them and entrust their safety to non-magic users? [Answer] Body guards are supposed to cover the weak points of the target. > > Invocations can last anywhere from 30 seconds to 5 minutes depending on the type and Power of the attack. > > > Mages must be relatively close to the area they wish to target. They can be separated only by a few dozen feet in order to be in range, or the attack won't hit. > > > Imagine how nice would it be that while the primary target is busy buzzing the main invocation, also the bodyguards start buzzing some other invocations. This would leave at least 5 seconds of vulnerability to a non magic attacker, or, even worse, would be totally useless against a ranged attack (an arrow takes less than 5 seconds to hit). Therefore the bodyguards need to make a living testudo around their protegee, protecting the openings which are not well protected by magic. [Answer] 3 factors: # Range Range of regular 9mm pistol: from 50 (effective) to 100 meters, [according to Wikipedia](https://en.wikipedia.org/wiki/Beretta_M9). A rifle can do a few hundred meters for effective range, and kilometers for maximum range. Range of a mage: > > Mages must be relatively close to the area they wish to target. They can be separated only by a few dozen feet in order to be in range, or the attack won't hit. > > > I don't know how much "a few dozen feet" is for most people, but for example five dozen feet are a little less than 19 meters. People in your world probably say things like "Don't bring spells to a gunfight". # Ammo Ammo for guns is only ever spent when you fire the gun. The ammo for spells, though, is mana (called orgone in your world), which is spent when you cast. A mage may find theirself out of mana to cast a fireball because they had been repeatedly casting non-combat spells, such as [Mine Manacoin](https://worldbuilding.stackexchange.com/a/112321/21222) or Naruto's spell Sexy no Jutsu. # Cost > > Witches exist at the top echelons of society. > > > But regular bodyguards don't. I am quite sure the salary of a gun-bearing goon is orders of magnitude smaller than that of a witch. It's like Jason Momoa and his bodyguards: [![Khal Drogo and his Dothraki](https://i.stack.imgur.com/YWF6h.jpg)](https://i.stack.imgur.com/YWF6h.jpg) Sure, they are less muscle than Momoa himself in a fight. But I bet their salary is less than, say, Terry Crews's and The Rock's. [Answer] Two witches performing magic in very close proximity to each other cause interference to each others magical "field". This causes spells to have reduced effect or even total misfires (possibly causing harm to their own side or even themselves). Additionally the witches have to pour more orgone into each spell to overcome the disturbance. This in turn causes more interference, etc. It also means the witch gets exhausted quicker. So it is best to use non-magical guards as body-guard/flesh-shields. Especially as (non-magical) flesh also serves as a damper on the interference itself. This allows for some cooperation between witches, but doesn't let them work closely enough together that they can be effectively be guarding each other. If a witch can draw orgone from other people (non-magical) the body-guard can also serve as an additional power-source for the witch. [Answer] # Magic disturb magic If two witches are casting spells one near the other, their magical energies start disturbing and causing an error in their spells. This disturbing in the magical field can increase the casting time, decrease the power of the spell, their accuracy or even make them untestable and explode. That is why witches use non-magical bodyguards. # They are "very valuable" for society. Too much As you said, they are very valuable, that means expensive. Hire a witch as a bodyguard is very expensive, you could hire a dozen magicless bodyguards. # Witches envy Witches use to envy and hate other witches, all of them want to be the most famous and powerful, and so they can't have another witch as a friend, one of them would backstab the other at some time. # To counteract weakness Magics takes time and energy to cast. If two witches were casting a spell at the same time, during a few seconds they would be vulnerable. Magicless bodyguards don't cast magic, and so they can protect witches while they cast magic. Even more, what if a powerful rival witch cast anti-magic? Both the witch and his witch bodyguard would be useless. Having a bodyguard which doesn't relieve on magic is can literally save your life. [Answer] ## Witches coordinating and protecting each other While it is not plausible to have Witches protecting each other outside of battlefield, coordinating Witches IS a plausible battlefield tactic. One Witch could shield against attacks, while another is summoning up a powerful lightning bolt. And each Witch could take turns attacking and defending, without any of them being of a lower rank. * Magical shields may be impervious to magical attacks from the inside. And the guarding Witch will have to time the summoning and destruction of these shields. * This by no means replaces the regular Shield guards. Regular Shield guards have higher agility and can react faster to attacks and reduce the impact reaching the Valuable Witches. ## Why this tactic is rarely used * Increased vulnerability. While the coordinating Witches can hold ground for longer, they aren't really an impenetrable combination. Stronger Witches or well-planned distributed attacks can bring them down. The enemy now gets to concentrate their attack on a single area and kill two Witches instead of one. * Reduced agility. The defending Witch reduces the agility of the troops. The non-magical shields are very agile and can track and attack quickly. You can consider this analogous to attacking from the sea Vs from the land in real-world. * In general distributed attacks are more effective than concentrated defences. While a Witch launches an attack from one direction, they are effectively defending the other Witches in other locations. [Answer] Note: some of this answer is based on more recent developments in your magic system, that do not appear to have been established at the time this question was asked. Limited resources Eventually the defensive and offensive casters will run out of orgone, and then they're toast. A non-magical body-guard is able to continue fighting and protecting for much longer than the casters orgone supply will last. When they run out, their body-guard will keep them save until they can get to a safe place to recharge. Additional resources If the caster's body-guard is capable of storing orgone and allowing the caster to channel it, they not only gain protection, but also access to far more resources. This greatly extends their spell casting ability in ways that another caster cannot. Vulnerability while defending another It may be possible to target multiple entities simultaneously, but it is extremely difficult and requires immense focus. This is especially prominent when channeling defensive magic because the effects are only active while being channeled. You cannot just put a shield around someone and go back to other things, you must actively maintain the shield without losing focus. This means the caster can effectively focus on defending them self OR another, but not both (at least not with significant weakening of the effects). So, if they are focused on defending another caster, they are left extremely vulnerable themselves. This tactic is not uncommon, with certain casters specializing in defense magic, but it is only workable if there is also a body-guard (or multiple in some cases), trained in advanced physical combat, as it is not possible for them to defend the caster without also defending them self. ]
[Question] [ This question already has answers here: [What all stops working when I pause time?](/questions/30001/what-all-stops-working-when-i-pause-time) (25 answers) Closed 7 years ago. Suppose there is a person who owns a device which can stop and resume time. When the person stops the time, will he be able to see the things around him? I imagine not, because stopping time will stop the movement of photons itself, thus depriving the person of his ability to see. Or, is it such that particles with no rest mass like photons continue to move? [Answer] # Time to Load Up on Sunscreen The unfortunate truth is that there is no way to make time stop stories work from a physics perspective. There isn't even a good way to make them work by pretending that everyone else slowed down considerably / the protagonist sped up considerably. It all creates significant physics-related challenges. (this doesn't mean they can't be good stories though!) Note: This post concerns only vision during a time-stop event. Motion (including breathing) in such a scenario has its own crazy ramifications, but since the question was just about vision that's what I'm narrowing this post to. To start things off, let's assume that whatever needs to occur within the body of the person able to perceive time "normally" (the "protagonist") just works. Any chemical/electrical/etc. process that occur within the bounds of any cells of the protagonist "just work". That will simplify things considerably and remove a lot of unnecessary discussion. Within the bounds of that premise, let's look at how to make vision work. As you suggest, vision requires the continuing motion of photons. Let's further assume that the stopping of time does not affect photons and consider the consequences. OK, but where do those photons come from? # Where Photons Come From ## Case 1 of 4 – inside a building, lightbulbs still working If the protagonist is inside a building and lightbulbs work the existence of photons would suggest that the electrical grid still works. That would mean that, depending on the area, wind, water, gas, coal, solar (etc) power generation still works. Since most of those methods rely on turbines turning, it would seem that time stopped in a very particular way indeed! Even solar power requires chemical reactions to occur. ## Case 2 of 4 – inside a building, lightbulbs not working If the protagonist is inside a building and lightbulbs do not appear to continue functioning, it would suggest that the electrical grid stopped functioning as expected. That would seem the most consistent with time stopping. ## Case 3 of 4 – outside, more than 7 minutes of light available If the protagonist is outside and has more than 7 minutes of available light (the time it takes for the light from the sun to reach the earth) it would suggest that nuclear reactions can still take place. That starts to get a bit awkward, because then we need to start discussing what nuclear reactions do work and which don't – such as allowing fusion but disallowing fission. And you're going to want to disallow fission because otherwise when you re-start time you're going to see nuclear meltdowns occurring all over the world (presuming you stop time for a while). So this is maybe possible, but you do have to allow fusion to function as usual while disallowing fission. ## Case 3 of 4 – outside, less than 7 minutes of light available If the protagonist is outside and has less than 7 minutes of available light, the suggestion is that time stopping is universal. Interestingly though, if the protagonist stopped time for 5 minutes and re-started it the world would receive 2 more minutes of light before being plunged into darkness for 5 minutes. That would be one way to let the world know that someone with time stopping powers (which oddly does not affect photons) exists! # On What Photon Interactions Look Like ## Case 1 of 3 Let's say we take the path that says "photons continue to reflect off of matter, except for the protagonist" because it seems the cleanest. I'm afraid that in such a situation the protagonist will be robbed of the ability to see colors. *And what they would see would be insane*. Oh, and it would probably kill them. The reason being that the creation of colors is a function of particular wavelengths being absorbed and others being reflected. If no light is absorbed it must be reflected, which would mean everything would reflect as though it were a mirror. Let that sink in for a second: everything behaves like a mirror. People are 3D mirrors. Buildings are 3D mirrors. Each blade of grass is a 3D mirror. The only thing the protagonist sees then is what is reflected in those mirrors. Note:** Because these perfect reflectors are not mirror-smooth they will not generally reflect actual images (though clear glass would become a mirror itself). Due to micro scattering of light, most surfaces would shine white. If they are on the dark side of earth all they would see are reflections of the stars everywhere, reflected very oddly and generally in a non-distinct way (due to micro scattering). Visually distinguishing up from down could be very difficultand the entire scene would be incredibly confusing. If they are on the bright side of earth things get a lot worse. As we have already established that the protagonist interacts with light normally, that means they are the only absorber of light within visible distance in a world full of mirrors. The amount of reflected light that hits them would be enormous and quite likely fatal after a relatively short period of time. Even a limited, non-fatal jaunt would likely result in some form of light-blindness (duration and permanence dependent on exposure). ## Case 2 of 3 Let's say that you don't want to only see unintelligible stars or suffer immediate blindness and burn to death. Your other option in that case is to have materials absorb and reflect photons as occurs in normal time. This works much better for your character when they are in the "time stop" state. What works less well is what happens to everyone and everything else. Let's say that you stop time for 5 minutes – a reasonably short amount of time. Over the course of those 5 minutes people, buildings, plants (everything) is going to continue to absorb energy, but won't be processing it in any way as chemical reactions have stopped (if they haven't, people would be walking and talking as normal). Once you turn time back "on" however, those people and objects are all going to receive 5 minutes worth of energy in a fraction of a second. To put this in perspective, let's say that they receive the full dose of energy in 1 second. Five minutes have 300 seconds. Receiving all of that energy in 1 second would be like putting your skin under a 300× magnifying glass in the sun for 1 second. For an idea of what that feels like, a typical decent-quality hand-held magnifying glass could have a magnification power of 10×… and less if it's a cheap one. This is 30 times more power than that. Without really going into some calculations I'm not sure what would happen exactly, but I think it's reasonable to expect that a living cell that had 5 minutes worth of good solar energy released in it instantly would die. Even without secondary effects on the next layer of cells (which would undoubtedly occur), the result is that everyone on the sunny side of the earth would simultaneously shed a layer of skin from any exposed parts - yuck! More importantly though, their eyes would also be exposed to that same effect and could be seriously impaired by it. I hope they were blinking when time stopped! Undoubtedly a number of things would also instantly catch on fire. Piles of cooking flour that may be in the sun, gasoline, hay chaff, etc. Also no fun. ## Case 3 of 3 Courtesy of MichaelS in the comments. In this scenario there is no interaction at all between photons and matter – the photons just pass right through. This is an interesting one because it avoids killing the protagonist or injuring large swaths of people/animals/structures, so maybe it's the way to go? It depends on what you really need to see. If you really just need to see the sun and other stars this will work great, because there is nothing for the light to bounce off or to absorb it - so all you would see are the light emitters. The first major downside is that you would only see things that emit light, and by "see them" I mean "see light coming from its location". Visually it would be like being in space, but with the sensation of gravity and the reality of bumping into things you can't see. The sun and stars would also be brighter, but I'm sure you don't want to stare into the sun anyway. The heat from the sun would be worse than standing at the equator at the height of summer and there is no such thing as shade, so I wouldn't recommend existing in such a state for more than a few hours at most or you'll risk succumbing to heat exhaustion. [Answer] The most consistent way to "stop time" would be to presume the world is actually a simulation of some kind, and what you have done is to halt the time coordinate in that simulation. You are now permitted to interact with it using some different simulation layer at a particular point in time. How that simulation layer gives you interaction with the particular point in time is then the question. If the system was carefully designed for a human-like creature within the simulation to experience it, then they could do a quick sampling of the macro-state and build a high-resolution static model of the universe. Have the "time stop" individual interact with that static model (using whatever rules the simulation chooses for this special case), and have changes propagate in an implemention-defined way when time "restarts" (including, for example, your position). Such actions would cause arbitrary anomalies. And as physics of the frozen world does not apply while the world is time stopped, nor does it apply to transitions, there isn't much problem. For a practical example, imagine if a snapshot of the universe's state is taken. The "hole" where you left is filled in with some kind of interpolation. The "hole" where you are is a mixture of cleared and pushed aside. Physics runs for 10 ns, but with an extra pressure component pushing your matter out of the way of areas of dense matter in the snapshot. Then the physics is reset with your new position. Definition of what "you" are varies, naturally. Stuff you shed and absorb is defined through some kind of algorithm or decision process. In this case, solid objects might to be almost completely impenetrable by the stuff you can manipulate. Air might be a bit thick, and water like molasses. Light mostly works. But this is because the time stop isn't really time stop, but rather a directed attempt to provide what we "instinctively" would call a time stop experience based off our large-scale illusions of how the world works. [Answer] The question here is somewhat ambiguous. Were you to stop time, you of course won't be able to see anything at all because you wouldn't see the photons. However, if your story has this level of real-life physics, then you'll have problems trying to describe how you halt time. [Answer] If this person truly stopped time, and somehow not stopped time for themselves, then you are right, they would not be able to see. What you see in movies and stories where "time stops", is more of a pausing of all momentum. So things with mass stop moving, but things like photons (massless) continue to work. However, even there, you have inconsistencies, since photons are generated by things like electrons (which have mass) oscillating between energy levels in the atom. Of course, that does not necessarily mean they are moving, but rather gaining and losing energy, which is hard/impossible to picture happening without movement. Still, I think the inconsistencies at that level would be the sort of thing you can hand-wave away. I think a story that explained that rather than "stopping time" that what the device did was "pause momentum" would be more accurate, to the point of being far more interesting on that score. [Answer] I will propose a simple model. Let's say your protagonist is able to create a spherical "bubble" around him, and cause time to flow differently inside and outside of the bubble. This difference in the "flowing" of time means that all physical processes develop at a different pace. To create the stop effect, the rate at which physical processes work inside the sphere would have to be much faster than the outside rate (infinitely faster if we are talking about true timestop - we will get there). Let’s keep things very simple. Suppose everything inside the sphere is, let's say, three billion times faster than everything outside, meaning that our protagonist could live an entire lifetime of ~ 95 years while one second passes outside. This means that the energy per unit of (inside) time that will reach any energy collection-detection system (e.g. the human eye) inside the sphere, originating from an object outside the sphere will be three billion times smaller than what would be detected ordinarily. Thus, our protagonist would be pretty much in the dark. Still, in principle, special equipment could enable him to "see" the outside world - by collecting and amplifying this weak radiation, much like what we do when we explore the universe with telescopes and sensitive energy detectors. There are, of course, many open questions, whose answers will probably depend on the exact nature of the interface between those two "worlds" and how the light would behave there. For example, do incoming radiation suffer a frequency shift? How is incoming light affected by optical phenomena in the interface (refraction, reflection, diffraction)? Notice that the speed of light in vacuum would have to be different in each world! In addition, what I described is an extreme slowdown, or apparent timestop if you like, but not true timestop. Each step closer to true timestop takes you a step closer to total darkness - if the world outside does not move at all, this means that the physical processes inside the bubble happen infinitely faster than in the outside, so that millennia would pass without a single electron-volt of energy crossing the boundary... [Answer] # Real time The question, as posted, makes little sense. As it is written, it seems like you want to know the answer in a hard SciFi setting, i.e., you want to have everything to be real as in our physical world with the little addendum of allowing to freeze time for the whole universe except one little bubble around your own person. I know that you did not ask whether it is possible, but how one detail (photons) would work if it were possible. This is a rather technical question which could only be answered if we knew how this stuff actually works. Unfortunately, there is no consensus about what time actually is. See <https://en.wikipedia.org/wiki/Philosophy_of_space_and_time> for a rather interesting list of possible interpretations. Note that physics doesn't help there at all, so far. It knows a lot about how (space)time behaves, but nothing much more. For example, they don't even know for sure whether spacetime is quantized, what it is "really" made out of, and so on. For example, neither physics nor philosophy can tell us whether it would be more correct to describe time as in "past - now - future" or only "before - later"; i.e. whether the present moment is something that actually exists, physically (and is different from all moments past and future). It is a pretty interesting idea ( <https://en.wikipedia.org/wiki/Eternalism_(philosophy_of_time)> ) to say assume there is no "now", and all moments in time (sic) are the same, existing at the same time (sic) etc.. Note that the word "time" is used in different levels in the previous sentence, and the second one actually makes no sense at all. # Story time If you tell us which kind of time you'd like to use in your particular story, people may come up with ideas about whether/how seeing is possible. In a hard science setting: no chance, just pick your favourite handwavium visual effect and run with it. Or invent some witty way to get around the issue. For example, if you were to ask how to stop local time, that would be easy and paradox free (check out "Marooned in Realtime" for a wonderful book about that). [Answer] If the stopping of time required photons to stop moving I would think everything would be literally frozen, as in 0 degrees kelvin and then it would cease to exist because if things aren't moving then no forces are working and if force is zero and time is zero and speed is zero and acceleration is zero then mass is zero and energy is zero. Then universe implodes. Maybe? ]
[Question] [ I want to make an alien species evolve without fear, or atleast not fear as we know it. Intelligent life, as I understand it, requires fear to encourage an organism to keep itself alive. What emotion or sensation could replace it? Pain? Competition? Anger? What evolutionary path would lead to such a development? [Answer] Strong Emphasis on Long Term Reward The purpose of fear is a prescriptive measure in humans to have them avoid getting into bad scenarios which have short term gain. Should primal man venture into the night? Fear says no, because you'll get eaten by wolves. Should modern man rob a bank? Fear says no, because you'll get caught and have to go to prison. In both of these situation, a cost-benefit analysis would suggest the same thing fear does, so why is fear necessary? The answer is because humans value short-term gain over long-term gain. Thus, in order to balance the scales back towards long-term gain, something is needed - a fear factor to help stop humans from wanting short-term when the long term is negative. However, if you made the alien species such that they de facto tend towards the long-term and rarely concern themselves which short term, then they wouldn't need fear, because they'd always look towards long term benefit. On the flip side, they'd actually have a problem with spontaneity - in other words, it's unlikely that they'd be able to make snap decisions because of this focus, so they'd need a kind of emotion that humans don't have - a hasty emotion which focuses on the present. [Answer] Whenever one of these base emotion questions come up, I like to bring up [Lövheim's Cube of Emotion](https://en.wikiversity.org/wiki/Motivation_and_emotion/Book/2015/L%C3%B6vheim_cube_of_emotion) [![The Cube](https://i.stack.imgur.com/N5M3ym.jpg)](https://i.stack.imgur.com/N5M3ym.jpg) Now I have to put a disclaimer here, before I go any further. The connection between monoamine neurotransmitters and the eight "basic" emotions that Lövheim proposed deserves some skepticism. He proposed it in 2012, and very little follow up has been done. In addition, I assign meanings for the transmitters which are decidedly oversimplified. However, for writing and worldbuilding purposes, I find this overreach proves very effective in exploring emotion, so I continue to use it despite its questionable pedigree. In Lövheim's cube of emotion, the 8 basic emotions of affect theory are paired to combinations of the three monoamine neurotransmitters: noradrenaline, dopamine, and seratonin. For example, fear/terror is associated with high dopamine, low noradrenaline and low seratonin while joy is associated with high dopamine and seratonin but low noradrenaline. This connection between emotion and neurotransmitter levels, were it to be found to be true, would be a very powerful statement about how our brain works. For worldbuilding, I take it one step further. I looked at how these neurotransmitters operate and tried to over-distill it into something for worldbuilders. * Dopamine -- Dopamine is associated with rewards. It's actually not the getting of the reward that causes dopamine, but the potential. Dopamine is a neurotransmitter which is used to let the neocortex notify the limbic system that it thinks there is a reward somewhere in the area, so the limbic system should act in a way which can uncover this reward. Basically, the thinking brain is happy with the situation it's in. * Seratonin -- Seratonin is heavily associated with the lower parts of the brain - the reptilian part of the brain. It spikes after we've had a good meal, among other things. We can treat it as a signal indicating the body is happy with the situation it's in. * Noradrenaline -- This neurotransmitter is highly associated with unexpected changes. There's some feedback loops between our sensory inputs and our brain's predictions about the world which cause noradrenaline to spike if the world turns out different from our expectations. Thus we can treat this as a signal that things are changing unpredictably. These oversimplifications lead to surprising insight into how these emotions flow. Fear/Terror is associated with high dopamine, but low noradrenaline and seratonin. Through my oversimplification, we can say that fear is what we use in a situation where our body is very unhappy with what's going on (low seratonin), and we see that the situation is unfolding in that bad way predictably (low noradrenaline), but we see a way to make the situation better (high dopamine), perhaps by running in a useful direction. Contrast that with distress/anguish, with its high noradrenaline and low dopamine and seratonin. In that case the brain doesn't see a way for things to get better (low dopamine), and there's constant hard to predict stimulus (high noradrenaline), which is the thing causing the distress. If it ceases to be unpredictable (noradrenaline goes down), we fall into shame/humiliation. And if you think about what happens as a person simply gives up the fight, this seems awfully accurate for how many simplifications we took getting here. So what are some of our options? * One option is to simply never get into this situation where the body's unhappy, the world is predictable, and there's reward in sight. We could always have behaviors which ensure unpredictable behaviors occur around us if the body is unhappy and there's reward in sight. Indeed, there are some people who, if pushed towards fear, get angry rapidly. + A fascinating variant of this is when you punish fear responses. This decreases the sense of a reward being around, so dopamine goes down. You get shame/humiliation. If you consider an individual who is in a trapped unhealthy relationship, this starts to feel uncomfortably accurate. Perhaps the environment for this alien simply never rewards seeking rewards in this scenario. * You could pick different axes. Different axes would yield different base affects. One might consider cylindrical or spherical coordinates rather than these rectangular ones. For example, you might have a combined unpredictable world/rewards are available into one neurotransmitter with a second that moves it back and forth between the two like a knob. That kind of limbic system replacement would lend itself to completely different fundamental urges. * You could identify a better response. Considering fear as what humans do when they see a reward, but their body is unhappy and the situation isn't offering any unpredictable insights, you could ask "what might my alien do different." It's a hard one to explore, since we're so used to the fear responses in humans, but fun to try. The result is an alien which has "fear" in the sense of this cube, but their response is very different. No matter what, you're looking for an environment where the stereotypical responses to this scenario don't apply. I find that opens the door for a lot of brainstorming, so have fun with it! [Answer] At the species level, a high reproductive rate can make up for a lack of fear. Beyond that, if the species is significantly more dangerous than the other predators in its natural domain, the absence of fear would be advantageous to their survival since they would benefit from the greater reward which is usually associated with greater risk. So don't replace fear with another emotion. Just make them extremely fertile and dangerous. [Answer] ## Curiosity and Optimism What happens if you remove fear from an ordinary person? We can point to one famous example that has been studied in real life: The case of [S.M.](https://en.wikipedia.org/wiki/S.M._(patient)), a woman who due to a rare genetic condition has been left without the ability to feel fear. When confronted with situations that would ordinarily cause someone to become cautious, she would instead become curious and inquisitive. For example, when confronted with dangerous snakes, she would become fascinated, asking many questions and repeatedly asking to touch even some of the more dangerous specimens - and this is in spite of having previously stated a dislike for snakes. Similarly, she would happily take the lead in haunted houses and indeed reported excitement and enthusiasm Though a lack of fear led to her getting herself into many dangerous situations - she had been held at knife and gun point a lot, to give one example - she continued to have a generally positive outlook and seemed immune to PTSD If your aliens are comparable to humans, we can imagine they would experience similar emotions when faced with potential danger. Building from this, we can also point to factors that might guide a species to evolving an underdeveloped sense of fear as a whole, instead of as a rare anomaly in one or two individuals: * The environment is generally safe. For example we might imagine isolated island-like conditions, where almost no threats exist and fear responses are pointless * Exploratory behaviour is a competitive advantage. This could mean the environment is rich in novel and (potentially) beneficial experiences, like hidden food sources * Individuals are expendable. In a eusocial species, non-reproductive members might be expendable enough for the attrition to outweigh the benefit of more quickly and aggressively searching for food * Directly disadvantaging the fear response would also help, though it’s difficult to identify useful examples to suggest on this front These are just a few examples of factors that might lead to a species losing its ability to feel fear - in general I would suggest an environment that strongly rewards curiosity and lacks many ways to kill the proverbial cat would be most likely to enable your fearless aliens. ]
[Question] [ In approximately 50 years, NASA and many other international space agencies collaborate to create a cloud top base on Venus. The astro-geographers on the station (aka the loser's club) want to go to the surface to study the mineral formations. The people who know what they're talking about, however, say that they can't do that, due to the high temperatures. But the geographers say that they will dig into venus and find a dead lava tube to live in. My question is: Can they do this? (Not minding how to get there), and how deep would they need to go to have livable temperatures? [Answer] The two answers you already have are correct, but I think it is worth the time to add some more details. ## The Question After all, the idea is quite reasonable. Anyone who has been in a cave knows that it initially gets colder as you go down. Similarly, my native Florida is practically the land of springs, and anyone who has visited one knows that they are 72 degrees year round - quite refreshing during the hot summer days. We all know that it eventually gets hotter as you go deeper, but it initially gets colder, so why shouldn't there be a sweet spot on Venus? ## The answer on Earth Of course to answer that question we just need to know why it initially gets colder on earth as you travel deeper. The answer is that it doesn't really. Ground temperatures near the surface are actually just determined by the average yearly temperature of the region. The outer layers of the surface act like a big blanket, and of course there is a lot of ground underground (citation needed) so it changes temperature slowly. As a result, temperatures in the caves/aquifers that we are used to eventually reach and stay at the average surface temperature. In other words our Florida springs are 72 degrees because if you average out winter and summer Florida is 72 degrees. Therefore during the summer it is colder underground, but during the winter it is warmer. ## The answer on Venus As explained in the other answers though, the situation on Venus is much different. There is no winter and summer. Not even a day and night. While there is certainly weather on Venus and I'm sure the temperature varies as a result, it never reaches anything less than "near-instant death". As a result, nothing under the surface is ever colder than that either. There is nowhere reasonable to go. Unless of course you really don't like your geographers. In that case an underground lava tube may be a great home for them. [Relevant XKCD.](https://what-if.xkcd.com/132/) [Answer] Short answer: # *HELL NO* Surface temperatures on Venus approach a toasty 900degF (~475degC). Though heat is radiated from the planet, there is no surface cooling as on Earth. Venus has volcanoes and presumably some amount of radioactive decay and probably a hot metal core, much like Earth. There's no "sweet spot" anywhere close to that planet. Closer than your cloud top base. [Answer] As Arkenstein implied in their [comment](https://worldbuilding.stackexchange.com/questions/147113/could-you-live-in-underground-lava-tubes-on-venus/147115#comment459753_147113): ## No The surface temperature of Venus is uniform. It does not get any cooler as one approaches the poles, or at night, or any of the variety of things that change temperature here on earth. There is therefore no way for the temperature to get any cooler beneath its surface; any heat sink capacity has been used up for millions or billions of years since Venus' runaway greenhouse effect took effect. So under the surface, it'd be hotter than the surface. The deeper you might dig, the hotter it would get. There is no "sweet spot", no respite from the heat. [Answer] Kind of? Despite what others said, temperature is not actually your problem. Pressure is. The pressure on surface is over 90 times what you want inside your habitats. Not to mention that pressure comes in the form of super critical carbon dioxide at 740 kelvins. What this means is that the ratio of temperature difference is smaller than the ratio of pressure difference. So if you find a way to deal with the pressure, the heat won't be an issue. I'd go for a plant that uses power to de-pressurize the supercritical carbon dioxide. Then give your habitat multiple pressurized shells with inner shells having progressively more survivable pressures. This is not mechanically as good as one shell but it would be easier to construct and if you fill the intermediate shells with de-pressurized carbon dioxide you will also get cooling "for free". For as long as the power plant works and carbon dioxide gets cycled anyway. You could also extract some water from the carbon dioxide. Probably not much but given that you'd want the habitat very well sealed anyway, maybe enough? Some limitations on your power plant would apply though. If the power is produced with a heat engine of any kind or in general with a process that relies on temperature difference, you cannot use the cooling to create that temperature difference and then use the power produced to run the cooling. Well, you can, but you might have to name your colony the barony of M√ºnchhausen for it to work. Still, nuclear reactions can produce high enough temperatures for it to work even with cold end at 740 kelvins and other energy sources are possible. Maybe that supercritical carbon dioxide has flows that you can extract energy from? In any case you'd probably need lots of power. And good redundancy with it. The lava tubes are not really doing anything for you. Except trapping you underground and under a sea of supercritical carbon dioxide if things go wrong. I'd go for a rig or ship that floats in the carbon dioxide instead. Much easier to evacuate to those cloud top bases or to supply or build. And it can be moved. ]
[Question] [ I’d like an alien to be warm-blooded, but have external gills. Imagine a kind of giant crab or woodlouse (pillbug) which spends part of its time on land and part of the time in the sea. However, external gills will be an enormous heat loss for a warm-blooded creature whenever it enters the water. All that surface area, shedding heat into the water like it is going out of fashion! The normal biological solution to heat loss in an extremity is to set up a countercurrent exchange system between the outgoing and incoming blood vessels. That would work fine to save heat; chill the blood as it leaves the body for the gill, warm it up again as it comes back. [Diagram of countercurrent vs normal flow](https://en.wikipedia.org/wiki/Countercurrent_exchange#/media/File:Comparison_of_con-_and_counter-current_flow_exchange.jpg) But there is one teensy, weensy problem – the countercurrent would also do the same to oxygen, and not in a good way! The outgoing blood would pinch the oxygen from the returning blood and thus no oxygen would ever get from the gills to the body. Oops. So, can anyone suggest an alternative, biologically plausible, method of saving heat in an external gill? Otherwise my aliens will be restricted to quick dips or only going swimming in the warmest of tropical seas. [Answer] You actuallycould use a way penguins use to protect from heat loss thorough their feet. Just make blood vessels really close to each other, to get concurrent flow.Actually, humans have that, too: [![Image of concurrent flow in a human arm](https://upload.wikimedia.org/wikipedia/commons/1/18/Arm_counter-current_flow.jpg)](https://en.wikipedia.org/wiki/Countercurrent_exchange#/media/File:Arm_counter-current_flow.jpg) That way, blood entering gills will be cold, minimal heat loss will occur, and when going back to the body, blood will collect heat from the one that is about to go to the gills. Now note that in humans and in penguins it is essential to supply oxygen to our arms and feet, and to take away carbon dioxide. The problem you are invoking is next to nonexistent - for gas exchange to occur, we need a really thin epithelium - that's why counter-flow in gills is so effective, and that's why gills and lungs are so delicate. Blood vessels in gills and lungs are delicate, too. But the ones that lead to and form them are not. These are thick and sturdy, and almost "airtight". If you need a proof, move your finger. If you can do it, then you know your blood has not lost oxygen going to your hand. Blood vessels have an inner layer, two elastic membranes, a muscle layer, and an outer "tunica" - not much of a border for heat, but a lot harder for oxygen to penetrate than a few layers of cells evolved to be easy for oxygen to move through. It works well for penguins barefoot on ice. So it probably could work well enough for gills, if tweaked a bit. [Answer] The tough issue to solve is that you need a maximal gill surface for oxygen exchange, but this surface will allow more heat to be lost. The only way to solve this is to somehow imagine a way to coat your gills with a thermally insulative substance wich still allows oxygen transfer. So what if this substance was... ## Air. Trapped in microfur (I liked the word). Air is a good thermal insulator and we can guess that oxygen will have no problem diffusing in it. Your alien will have to coat its external lungs with a thin layer of air. How? With microscopic hairs imprisoning bubbles of air (something close to the [diving bell spider](https://en.wikipedia.org/wiki/Diving_bell_spider) web bubbles, but with hairs). In fact, I call it hair for a lack of proper vocabulary (english is not my first language), but "organic micro tubes" would be a better description I guess. This way, air will stick to your tubes, forming a layer of maybe half a millimeter, separating your breathing area from the cold water, insulating it quite well, while still allowing oxygen to diffuse in the air layer from the oxygen-rich water. See this paragraph about the air bubbles imprisoned in the net of the diving bell spider: > > Wikipedia: > > > Diving bells are irregularly constructed sheets of silk and an unknown protein-based hydrogel[9] which is spun between submerged water plants then inflated with air brought down from the surface by the builder. Studies have considered gas diffusion between the diving bell and the spiders’ aquatic environment. The silk, whilst waterproof, allows gas exchange with the surrounding water; there is net diffusion of oxygen into the bell and net diffusion of carbon dioxide out. This process is driven by differences in partial pressure. > > > So at least the diffusion part should work. I don't really know if the rest of my idea is realistic, biologically speaking, but well... I'd buy it! [Answer] You're describing bluefin tuna, which have a [wonderful net](https://en.wikipedia.org/wiki/Rete_mirabile) of blood vessels which allows them to maintain core temperatures much warmer than the surrounding water - and without losing circulating oxygen! From [Wikipedia](https://en.wikipedia.org/wiki/Tuna#Physiology), they: > > can maintain a core body temperature of 25–33 °C (77–91 °F), in water as cold as 6 °C (43 °F) > > > and > > achieve endothermy by conserving the heat generated through normal metabolism. In all tunas, the heart operates at ambient temperature, as it receives cooled blood, and coronary circulation is directly from the gills.[42] The rete mirabile ("wonderful net"), the intertwining of veins and arteries in the body's periphery, allows nearly all of the metabolic heat from venous blood to be "re-claimed" and transferred to the arterial blood via a counter-current exchange system, thus mitigating the effects of surface cooling.[43] This allows the tuna to elevate the temperatures of the highly-aerobic tissues of the skeletal muscles, eyes and brain. > > > Just because heat is being exchanged does not mean that oxygen also would necessarily be exchanged. This: "The outgoing blood would pinch the oxygen from the returning blood and thus no oxygen would ever get from the gills to the body." does not happen. [Answer] 1. Have them live in the tropics, then the heat loss is minor enough to compensate with calories. 2. use internal gills vs external, If the gills are enclosed and connected with a one-way-flow set of tubes you can get heat exchange going at both ends to mitigate loss, Imagine fish gills if the outlet was somewhere near the tail. You have the whole downstream exhaust tube to reclaim heat. This would be beneficial to a amphibious organisms anyway by slowing down the drying of gills in air. It could even evolve into a a dual lung/gill system in time. ]
[Question] [ Writing a story in which a human is trapped on an alien planet with an average temp of 6 Celsius, and I want to have the atmosphere be too rich in oxygen, but not to the point where an air tank is necessary. What combination of pressure and oxygen would make a human just functional? [Answer] Alas, I couldn't find exact details of what percentage of O2 would be the limit; The best I could find for details is the chart below. I did, however, find details on what overdosing of oxygen can do. Apparently, too much oxygen intake can lead to issues with how cells can function. It leads to overproduction of something called ROS, which affects how cells can intake nutrients and can damage tissues. Particularly at risk are the lungs, heart, and brain. For more details, I've provided some links below the charts. Hope this helps. [![enter image description here](https://i.stack.imgur.com/nuEg1.jpg)](https://i.stack.imgur.com/nuEg1.jpg) <http://www.emsworld.com/article/10915304/the-dangers-of-giving-too-much-oxygen> [Answer] It depends on the atmospheric pressure. [![Atmospheric pressure and O2 concentration](https://i.stack.imgur.com/fceIE.gif)](https://i.stack.imgur.com/fceIE.gif) This chart from NASA shows the relationship between O2 concentration, atmospheric pressure, and how comfortable a human will be breathing that atmosphere. You could actually survive in atmosphere with 100% oxygen, just at a much lower pressure than on Earth. On this chart you can see the border for survivable O2 toxicity in a 100% O2 environment is ~8psia, or just above half Earth's atmospheric pressure. With a pressure this low and with no gases besides Oxygen this planet would indeed be significantly colder than Earth, I would suspect even colder than an average temp of 6C. A thin atmosphere combined with a lack of greenhouse gases leads to a low surface temperature as heat from the sun is quickly lost. To bring your planet's temperature up it should probably orbit closely to a hot star and have a very low surface albedo (a very black planet) and/or trade some oxygen for a strong greenhouse gas like water (unlikely if your planet is so cold), CO2, or methane. Closely orbiting a hot star with a thin atmosphere would introduce more problems like solar radiation and a large temperature difference between day and night. Additionally you should not try to start a fire in an Oxygen/Methane atmosphere. Or in any high Oxygen environment for that matter. I don't have the precise math with me now, but there are some models out there which can estimate stuff like this. I can edit this later with more specific numbers if you'd like. EDIT: A planet just like earth but with a 100% Oxygen atmosphere would likely have an average surface temperate of about -20C. [NASA page on environmental conditions](https://msis.jsc.nasa.gov/sections/section05.htm#_5.1_ATMOSPHERE) This page describes conditions within a space-craft, however the same concepts apply. [Answer] Humans routinely breath 100% O2 without issue. Divers, astronauts and patients routinely breath 100% Oxygen. There are some dangers of High Oxygen concentration such as [absorption atelectasis](https://en.wikipedia.org/wiki/Atelectasis#Causes)(collapse of the small air sacks in the lungs) and the suppression the [Hypoxic respiratory drive](https://en.wikipedia.org/wiki/Hypoxic_drive) in [some COPD patients](https://en.wikipedia.org/wiki/Effect_of_oxygen_on_chronic_obstructive_pulmonary_disease#Mechanism) whose chronic CO2 retention has burnt out their normal CO2-realted drive, causing them to stop breathing. Most dangers, though are related to the high partial pressure of Oxygen. Science uses the measure of partial pressure of O2 to talk about the Oxygen concentration and pressure. Quickly stated, each gas in a mixture exerts a pressure equal to their percentage in the mixture. So at sea level, atmospheric pressure is 14.70 PSI. O2, being about 21% of the atmosphere, exerts a pressure equal to .21\14.7 =3.08 PSI. According to [Wikipedia](https://en.wikipedia.org/wiki/Breathing_gas), The minimum and maximum Partial Pressures of O2 for human life are 2.3 PSI and 14.5 PSI. > > The minimum safe partial pressure of oxygen in a breathing gas is > commonly held to be 16 kPa (0.16 bar). > > > The maximum safe ppO2 in a breathing gas depends on exposure time ... It is typically between 100 kPa (1 bar) and 160 kPa (1.6 bar) > > > [Answer] Other answers have addressed the issue of O2 partial-pressure that humans can tolerate. I want to point out other potential issues. Oxygen is very reactive. The higher the oxygen content, the easier it is for a fire to start / spread. And anything that can oxidize will do so more quickly when exposed to the atmosphere. A 100% oxygen atmosphere is not very plausible, AFAIK. I don't think any naturally-evolving life could maintain it, since it would always be reacting with things to produce other gases (e.g. CO2). --- CO2 partial-pressure is also a big deal for humans. If it's too high, CO2 won't diffuse out of the bloodstream back into the air in the lungs, leading to changes in blood acidity as more CO2 builds up. [CO2 toxicity is a thing](http://chemistry.about.com/od/gases/f/Is-Carbon-Dioxide-Poisonous.htm). It's nowhere near as bad as carbon monoxide, and I haven't yet found a reliable number on CO2 partial pressure that would be dangerous. What I've found so far suggests that increasing oxygen partial-pressure wouldn't compensate for increased CO2 partial-pressure very much or at all. --- Interesting options for your atmosphere: Total pressure ~= Earth sea level. 60% O2 (upper limit for indefinite human survival), rest a mix of Nitrogen and other gases with a biome similar to earth. Just really aggressive plants or something. * Total pressure = ~twice Earth. Similar ratios to Earth for other gases (unless that makes too high a CO2 partial pressure). * Total pressure = ~twice Earth. 25% O2 (partial pressure more than twice Earth). Other gases very different from Earth. Maybe inert gases like Argon and/or Helium making up a large fraction? A heavy planet could hold its helium better than Earth, maybe enough to stop it from escaping into space at the top of the atmosphere? I haven't run the numbers, but maybe helium is still implausible. Make sure your atmosphere isn't combustible, though, because there's always lightning or other sources of fire. If the atmosphere could ignite / detonate, it would already have done so. --- I don't think you should consider less than Earth sea level total pressure, since a dangerously-high O2 partial pressure for humans would make it even more than 60% of the total gas, and then you'd need a mechanism to explain that. [Answer] It is primarily about partial pressure rather than concentration\, so pretty much any concentration can be just fine if the pressure is appropriate. The US EMU spacesuit uses 100% oxygen at 29.6 kPa (~4.3 psi) - <https://www.nasa.gov/pdf/188963main_Extravehicular_Mobility_Unit.pdf> The acute nervous-system oxygen toxicity (seizures etc.) that has killed a lot of scuba divers happens well above 1 bar / 15 psi; you wouldn't get this at sea level pressure even with pure oxygen. In between, you get lesser effects which increase with time - Wikipedia claims below 0.5 bar is fine indefinitely, for lung effects at least, apparently based on a 1987 study. \At very low pressures total pressure matters as well - 3 psi 100% O2 gives you significantly less oxygen than sea level air, even though the partial pressure is the same, because of vapor pressure of water (and presence of CO2 too, I think) in the lung. ]
[Question] [ I've just been on [What would be the ideal melee weapon for someone with superhuman strength?](https://worldbuilding.stackexchange.com/questions/22124/what-would-be-the-ideal-melee-weapon-for-someone-with-superhuman-strength) stating that big weapon in games are mostly unusable, even with superhuman strength. I was looking for answers about long-range weapons after reading the accepted one, then I reread the question again. (Some people did answer that a little). --- Now I wonder if a huge bow would be better than a giant arbalest or lances (or even that weird prehistoric device that was used to [throw spears/spikes](https://en.wikipedia.org/wiki/Spear-thrower)). How would they scale with strength ? Could a bow pierce multiple targets? I'm mostly thinking of medieval weapons: I'm pretty sure a real life [Team Fortress Heavy](https://wiki.teamfortress.com/w/images/thumb/0/08/Heavy.png/250px-Heavy.png?t=20111118215652) might easily win if this wasn't the case (with a huge anti-aircraft like weapon). Maybe [Anor Londo's archers](http://vignette3.wikia.nocookie.net/darksouls/images/e/e2/Silver_knight_dragonslayer.jpg/revision/latest?cb=20130210215028) might be even tougher enemies. The main question is: What is the best ranged weapon using this super strength? But of course it includes what new tactics it might need/add, and all kind of ranges (short, middle, long, enormous). --- Edits in response to comments: I'll keep it medieval. Let's say he's more of a mercenary, because of his strength he is pretty rich and has access to the best blacksmiths around the world, to fulfil his needs. So technology can't be too advanced (no carbon microfibre). But they can make special/high quality weapons for him. His contracts include helping small squads (10 people) to armies (hundreds and sometimes thousands). He doesn't like to work completely alone, because even though he is super strong, he is not any faster / agile / dexterous, or any more resistant. He controls his strength very well, so he will stop forcing before the weapon crushes (for instance a wooden bow), and trains a lot to know his weapon's weaknesses. Of course he has a melee weapon when it comes to this, but he prefers to kill as many as he can from a distance. [Answer] Much of this is more or less opinion. There isnt that much difference between vertical and horizontal archery. The difference in power between bows and crossbow-type weapons depends on the kind of materials used for the propulsion mechanism and the type of mechanism. There were basically four types of mechanisms used to propell projectiles. 1. Muscle Power 2. Counterweight 3. Mechanical Deformation 4. Torsion Muscle Power Many earlier ranged weapons used muscle power to propell projectiles over short distances. It began with throwing stones and spears, but quite soon got supported with levers and slings, creating weaponized slings and spear throwers. They were both quite accurate and quite powerful for the time over shorter distances. This would be a prime candidate for your scenario, although its usefulness will depend on the kind of armor and equipment the enemy is likely to field. Counterweight Not feasible. Couterweight based weapons are good for catapults, but are much too heavy and large to be used as a carried weapon. You would get much more use from all of the other options. Mechanical Deformation Yes, essentially bows and crossbows. With these it comes down to preference: The power of both depends mostly on the materials used and the size / form of the limbs. They are being loaded differently, and they use different types of projectiles. Crossbows seem to be easier to aim with, as they can be aimed "rifle-like", which seems to need much less training than using a bow, due to not needing to hold the tension of the limbs manually, and the way a rifle is aimed (especially at closer distances). You can ready a crossbow beforehand without much effort and let it stay ready some time, where with the bow this isn't really possible. With loading the main difference seems to be that with a bow you dont need to take your eyes off of your target, I believe the loading time is negligable when used with similar limb strengths. However, you could use much stronger limbs if you assist the tensioning of the crossbow limbs with a lever or a winch, both of which isnt possible with a bow. However, loading a crossbow with a lever or winch will take more time than tensioning a bow of lower power (obviously). I'd say this is more a matter of preference. If the priority lies with readyness, ease of aim or raw power, go with a crossbow. If Situational awareness and loading time is preferred, use a bow. Torsion Power This is similar to mechanical deformation power in that its power depends on the material of the torsion material, the length of the limbs and the length of the lever. You will not need as long limbs as with mechanical deformation, as the force will depend on the torsion material, not the limbs. A major example for weapons of this type is the Roman Ballista. You can achieve great power with shorter limbs at the price of loading time. Use this if you need a stronger weapon, but don't care about loading. Projectiles * Stones or Bullets * Spears * Arrows and Bolts * Chemicals * Bombs Stones, Rocks and Bullets are good against unprotected targets and, depending on the weight of the rock, against hardened targets the same way you might use a warhammer against armored targets. Its unlikely to penetrate a target with these, the only way to harm multiple target is either use a large enough rock or let the force of impact throw the target against another (if its that superhuman). Rocks are also much more available ;) Spears are practical and have a lot of mass behind their tip, making them deadly on short distances. However they are most useful when they are able to penetrate the target. They have more impact on non-penetrated targets in comparison to bolts or arrows, but not really that useful. They are well suited for combat though, as can be seen with the power of spear throwers (like the atlatl), Roman Pilums(although not technically a spear) and Greek Peltasts javelins. EDIT: apparently, both the Romans and the Greek used a sling in a similar way to the atlatl, called Ankule or Amentum, to propel their javelins over longer distances, which also gave them spin. Bolts and Arrows have good range and penetrate quite well, cut well and can be used to spread fire. While with some kind of arrows, you could penetrate multiple targets, but since you destry the aerodynamics of the projectile by going though a target, you're unlikely to hit anything (or even at the right angle to penetrate another). Obviously, if the Bolt is large enough, it has similar properties to larger rocks in that it will hit multiple targets (which has been used with Roman Ballistas). Chemicals are very dangerous for their size. In medieval / ancient times, greek fire and even quicklime could be used, although I think quicklime is only found later in the 17-18 hundreds. Not sure though. Both were highly effective weapons. Bombs: Well, you know... possibly, though I'd gauge incendiaries like greek fire to be far more likely. [Answer] In the Discworld books by Sir Terry Pratchett, Seargant Detritus the troll carries around a siege crossbow designed to fire bolts through city gates. He uses two types of bolt. Huge iron bolts to rip through stuff and special bundles of smaller arrows held together with twine. When fired the twine snaps leading to a cloud of arrows flying at his opponents. This weapon would allow your super strength guy to fire at multiple targets as well as break through doors and/or walls. On top of this the weapon won't break under the strains put on it. Another plus is that shields won't be much of a problem. Negatives are that it is slow to reload and that ammo costs will be high. It also can't really be used to wound. It may be hard to balance and aim due to its length so it isn't a precision weapon. As a bonus he can also use this weapon to club people with if they get in close. [Answer] I think a [spear-thrower (atlatl)](https://en.wikipedia.org/wiki/Spear-thrower) might work really well as a short to medium range, high rate of fire weapon. They were/are used as hunting weapons, with good accuracy for experienced users. Even if the guy starts out carrying something qualitatively different from things that are practical with normal strength, like a siege crossbow or flamethrower a [渡し守シャロン's answer suggests](https://worldbuilding.stackexchange.com/questions/53033/best-ranged-weapon-for-superhuman-strenght/53047#53047), an atlatl makes a great backup or closer-range weapon. A group of people with you trained in spear-fighting probably works great. They can carry extra spears for you to throw, and you can scavenge ammo from the battlefield if you or the enemy has pikemen. --- A bow or crossbow large & strong enough to take advantage of super-strength is probably hard to make. But a spear-thrower has no moving parts, so it doesn't need advanced metal springs or huge pieces of wood. The energy you can put into a spear with an atlatl should scale very well with strength, for a user of constant height / arm-length, and you can throw long spears without it being too big to hold easily. (I imagine that a strong enough bow might have to be really large, and maybe have a draw length longer than a normal human armspan.) Having to carry around a ranged weapon that doesn't fit through doors is a problem, even if the weight isn't an issue. [Answer] Superhuman strength would make heavy mass destruction ranged weapons more efficient than how they were already... Like a flamethrower, yes... it was medieval and it exists by 22-23 centuries already.... [![enter image description here](https://i.stack.imgur.com/XBkhc.jpg)](https://i.stack.imgur.com/XBkhc.jpg) The person with superhuman strength could carry countless rocket launchers,flamethrowers and more [![enter image description here](https://i.stack.imgur.com/7vBrS.jpg)](https://i.stack.imgur.com/7vBrS.jpg) Yes they are medieval too...there's also this version that can shoot 105-162 explosive arrows at once,it's heavy but it would be easy to carry around for someone strong enough. [![enter image description here](https://i.stack.imgur.com/DW53u.jpg)](https://i.stack.imgur.com/DW53u.jpg) And don't forget the triple crossbow, it requires the strength of 7-10 people to charge but this weapon is strong enough to shoot 50 kilograms up to 175 meters away, but usually it was used to throw explosive giant darts.Could your character carry this thing around and use it like a normal crossbow? [![enter image description here](https://i.stack.imgur.com/clmmA.jpg)](https://i.stack.imgur.com/clmmA.jpg) [Answer] Simplicity is best enough. Historically one of the deadliest weapons wielded by humans especially against animals is the stone. Humans are deadly accurate at throwing stones. After all, it's how David killed Goliath, but once you take into the deadliness of catapults and stone throwing then Goliath was outgunned. > > The practice of stone-throwing has deep religious, cultural and historical resonance, and is grounded in the age-old use of slinging stones among young rural herders whose task it was both to keep watch on livestock, and ward off predators of family flocks, and to hunt birds. > > > Collecting pebbles or stones and delivering at speeds only comparable to bullets or high-speed munitions by a person with super-strength would be formidable and terrifying to enemy combatants. A single pebble thrown at super-speed, in relative medieval terms, would be a tiny missile of invisible and silent death. Supported by a squad the super-strong stone thrower could hurl deadly missiles at rates while not necessarily approaching that of machine gun would be as devastating. Ammunition acquisition can be as simple as collecting pebbles. Nothing could be as low tech as that. This how the Palaeolithic waged its wars. A super-strong stone thrower simply carries the tradition to its logical conclusion. [Answer] OK, this is totally off the wall, but it might be appropriate. He's the muscle for an entire battalion of linked siege weapons. Instead of taking minutes to crank the counterweight up for a trebuchet, or pull the lever arm down for a catapult, he can set up multiples of these weapons in just a few seconds. One character with super strength, along with a crew for each of a half-dozen weapons, could launch a barrage of 300-pound boulders several times a minute. [Answer] # Conditions The person with super strength is in every other way a normal person. # Crossbow Without a doubt, a crossbow is the best weapon. Since the only advantage, he has is strength then all other skill-related aspects are the same as for anyone else. A crossbow is mainly limited to the users' ability to draw it. A crossbow can be scaled up to a certain level (the recoil doesn't knock him over). It's simple to use and accurate at that with minimal training. Spears/ thrown weapons Spears require a hell of a lot of practice and skill to use effectively. Throwing a massive spear sounds great but since he's in all other aspects a normal person, he'd probably just fall over himself since he will not be magically bolted to the ground. Thus he cannot use his strength to its full potential unless he puts his back against a wall or something to brace himself. Generally thrown weapons require a lot of training, axes, rocks etc could be used but they would still be quite unreliable. Bows Bows are great weapons, but not nearly as powerful as a crossbow. The crossbow is probably just as fast for our hero since he could probably draw a 200-pound crossbow with his two hands very easily. Or perhaps even a 400-pound crossbow with some leg-help without much effort. (Depending on his actual strength) Bows also require extensive training to be good. Medieval archers trained from a very young age up into adulthood to be consistent enough. Slings Slings are another alternative that probably requires more luck than skill to use effectively. # Summary Crossbows for their ease of use and great power coupled with our hero's great strength, are the best alternative. Crossbows that normal people would need specialized gear to draw is no problem for our hero. Crossbows using windlass systems as shown below are immensely powerful but took a lot of time to draw. Not a problem for our super strong hero. [![Windlass Crossbow](https://i.stack.imgur.com/RYkH5.jpg)](https://i.stack.imgur.com/RYkH5.jpg) In addition to this, add some really good armor to our hero (a shield?) and a substantial amount of crossbow bolts and you have yourself a super strong killing machine. [Answer] I’d say anything thrown because thinks like bows, crow bows and ballista are all restrained by their physical capabilities. You can only pull a bow back so far. Sorry this is the first answer I’ve given here. So here’s some elaboration. When using a bow the limitations are set by how much the bow will bend and how much the string will be able to pull back. So anybody who can pull the bowstring back to the fullest extent will maximize the damage the weapon can do. On the other hand, a thrown weapon utilizes the form and the strength of the person throwing it. So if someone has super strength they would possibly be able to thrown the weapon hard enough to reach maximum velocity. ]
[Question] [ In a [short](https://medium.com/universe-factory/coming-of-age-chapter-1-63377ccbac4c#.bhpelo16j) [story](https://medium.com/universe-factory/coming-of-age-chapter-2-59141b5a3edc#.6ldeices8) that I'm writing, there are four main characters: * Myra * Alytho * Syng * Theyna Myra and Theyna are female; Alytho and Syng are male. They all have a few things in common, one of which is that they, like all people and places in their land, have a "y" in their names. Don't ask me why; I thought it would be an interesting twist. It seemed like a good idea at the time. I'm aware of names on Earth that are similar - for example, in patronymic or matronymic societies, children might have their last name be the first name of one of their parents - followed by a common suffix. Does it make sense, though, for everyone to have one letter or sound in their name that is the same? I'm not asking for people to come up with some weird societal situation; I'm asking from a linguistic point of view. Other random information: * I haven't yet decided on country size yet, but I'm looking at something the size of Iran. * The setting is medieval. * There's really only one culture here, without a mixing pot of immigrants. [Answer] The most plausible explanation to me seems that the letter or sound carries a meaning. Consider for instance [Scandinavian family names](https://en.wikipedia.org/wiki/Scandinavian_family_name_etymology), which almost exclusively end in -sen (or -son in sweden) which means son of. Perhaps, in this culture it is custom to include something meaning 'child' in the name. The language would need to work a certain way for it to work flexibly like in your examples though. More specifically, it must be rather flexible with word order and possibly have pronounciation of wordgroups be decoupled from meaning. That way, the 'y' in Theyna and Syng can signify the same thing, despite not sounding similar. You could then have other words with the letter 'y' in it pop up which mean something related to offspring or a parental relationship. For instance, if the sun is still called 'Sun', 'syun' could mean sunshine or literally, 'child of Sun' [Answer] Linguistic markers like that are common. Usually they are found at the end of a word (some times at the begining), but it could occur anywhere. Such markers would occur when something is important enough to warrant spending a phonem on it to make sure there's no misunderstanding. My favorite example is from an aboriginal language that has 4 genders for its nouns: * Men and animals * Women and birds (birds are separate from other animals because women in the afterlife are associated with birds) * Objects * Small edible fruits The last gender always made me smile, because it's so odd. However, it says something about the brutality of their life. The availability of foodstuffs was so scarce that it was worth creating an entire gender for foods, presumably so that the members of the tribe were constantly aware of them. If you wanted to make a big deal about every character having a 'y' in it, I'd choose a society where the individual is a very important trait in society: important enough to have all names retain a linguistic similarity. [Answer] To expand on some of the existing answers and address some doubts raised in other answers: I think that this phenomenon can be well explained by something similar (but not identical) to inflection with [umlauts](http://en.wikipedia.org/wiki/Germanic_umlaut). For example, in German, the plural of a word can be formed by “umlauting” some vowel, i.e., by replacing it with another vowel according to some scheme: > > Apfel → Äpfel > > Garten → Gärten > > Mann → Männer > > Haus → Häuser > > Bistum → Bistümer > > > Note how the modified vowel may be located in different positions, may be part of diphthong (Haus → Häuser) and the umlauting is always indicated the same way orthographically, namely by placing two dots above a letter ([historically these dots originate from what was once the letter e](https://german.stackexchange.com/q/24000/2594)). Yet, in all cases, the meaning of the umlaut in this context is to indicate the same thing, namely a plural. Now, your names may originate from normal words of your language, where a “regular” vowel was replaced by y. Or with other word, the name-generating mechanism of your culture is (or was) to take a normal word and inflect some vowel to y. To give a more specific scenario how this may have happened: In your language, inflecting a vowel is a way to derive words of another word class from existing words. Compare this to the English appending of an y to a noun to obtain an adjective, e.g., as in sun → sunny or juice → juicy. Now, in our language inflecting a vowel of an adjective to an i is used to form a noun which describes something holding that property. For example: > > mora = brave → mira = somebody who is brave > > > alatho = red-haired → alitho = somebody who has red hair > > > This was also used to name people. When orthography was invented, your people considered it useful to make an orthographical distinction between person names and words regularly formed in the above manner (they did not have a capitalisation paradigm allowing for this) and thus they replaced i with y in person names. An analgous (if not the same) mechanism may have happened to place names, if your culture like to name places by their properties. For example: > > sung = cold → sing = a place that is cold > > > While umlauting is not done as rigourously as required by the question, languages are generally capable of handling such matters rigourously. For example there are only very few exceptions to the [Latvian naming scheme](http://en.wikipedia.org/wiki/Latvian_name). If the culture in question values consistency or being able to distinguish names, this may very well be a mechanism to prevent exceptions from this rule. This should address some of the doubts brought up in other answers, namely the placement of the vowel, the vowel being part of a diphthong and the fact that this is an orthographical feature. [Answer] In medieval Europe, names often (albeit not always) represented one of three things: * Where you (or your family) were from * Who you (or your family) were from * What you (or your family) did For instance, the Scotts and Irish used the Gaelic word Mac to create clan names such as MacDougall (literally: "son of Dougall") while the Scandinavians used the suffix -sen or -son; the French used the word de (and its cognates) to say where they came from, such as d'Orléans ("from Orleans") or Dupont ("from the bridge" -- not on its own highly descriptive); and all over you had names like Smith (any of a number of "smithy" trades such as blacksmith), Sawyer ("wood cutter"), and La Forge (literally "the forge", i.e. "blacksmith"). It's conceivable, then, that the letter 'y' in your names could be the demarcation between given and family name, where the family name could be any of these (and more): Myra could be from a house founded by someone named Ra; in the Old Tongue, maybe "tho" meant "carpenter", making Alytho something akin to Al[ice] Sawyer; Syng's family might come from the region known (or formerly known) as Ng. Sometimes names became more simplistic, literally meaning "son/daughter of [mom/dad]", so Theyna might be the daughter of Naytra, the son of Trayvis, the son of Visytra, etc. (In this form, you might conceivably have an Arabian-style "formal name"1 that strings all of that together: Theynaytrayvisytra.) None of this implies a stringent structure to the parts of their names. For instance, Syng could have a brother named Jokitryng, and their friend down the street might be named Sytrovalliance. You could even conceivably have a clan/house that took the full name of the founder, such that Myra's name might more accurately be Myraytro. Using the 'y' in this form doesn't necessarily require that it always be pronounced the same, either. For instance, at least in modern usage (and at least here stateside) the names McDonald and MacDonald have slightly different pronunciations, even though the former is technically just an abbreviated form of the latter. As far as constructing and pronouncing the names go, 'y' is just another letter and follows all the rules it otherwise would; there might have been a time when it strictly had a single sound, but the language has evolved, as languages do, in a way that makes these names easier to say and more natural to hear. --- 1 In ancient Arabia (possibly modern as well? not sure when or even if it fell out of fashion) a person introducing himself formally would for all intents and purposes lay out his entire geneology, stringing together the name of each father, father's father, father's father's father, etc. with the word ibn, meaning "son of", such that (for instance) I might introduce myself as: Travis, son of Richard, son of Robert, son of Robert, son of Robert, son of Jacob, son of... [Yes, this is accurate, as far back as I can remember off the top of my head, though we actually know our genealogy as far back as the Normans, pre-invasion of England.] [Answer] If they are all from the same country, then yes. It could be a custom in their nation to give children names with Ys in them. However, customs vary from area to area, so if they live in a large country, like the size of the US, then it is not likely. The same goes for different European countries. After all, Spain and Portugal are on the same peninsula, and have similar cultures, but they speak different languages and other things are different as well. To sum it all up, yes, it makes perfect sense if it is a cultural or national custom. [Answer] You've already followed one naming convention from your own culture: both your female names end in `-a`. While not all English female names end in `-a`, virtually no male names do (and indeed `-a` is commonly added to male names to mke a female equivalent.) Others have mentioned the endings on surnames that refer to the person's father or ancestor: `-son` in English, `-ez` in Spanish or `ov/ova` in Russian (Russian surnames change according to the gender of the person, and again we see the addition of `-a` to make the female form.) But I think you were more interested in given names, so I will consider that. In Chinese families, it is common for cousins of the same gender and generation to have similar given names. Thus all my (singaporean) ex girlfriend's cousins where called `Whui` something (female) or `Wah` something (male.) But the one factor which could cause a whole country to have a common feature in their names is religion. In Spanish the first name Maria is so common that most women called Maria go by their second name (the initial Maria often get abbreviated to `Ma.` in email signatures and similar uses.) There are many Spanish female names that refer to some aspect of Mary, even though they sound nothing like Mary. Lourdes and Carmen (named after holy places) and Angeles (short for Maria de los Angeles) are examples. I understand the Franco dictatorship made it obligatory for all girls to be named after Mary in some way or other, but I can't confirm this. For male names, I've heard more than once that Mohamed is the most common male name in the world, and I can believe it. Hebrew names for both genders (both those that are in current use and those that now sound old fashioned) often contain `el` meaning God: Daniel, Michael, Joel, Ezekiel, Elijah, Elishaveh (Elizabeth), Eliana, Batel, etc. [Answer] Although many good points can be found in previous answers, and in particular, with [Kromey's](https://worldbuilding.stackexchange.com/a/34212/9685), I think we could devise a way to get it. And Spanish could be a source of inspiration. I don't need to come back to the whole "son of" thing. There are plenty of examples throughout the world, and those have already been presented. Furthermore familly names (particularly) derive from * names of familly members (e.g. Johansson), * location, * profession (e.g. Smith), * animals (e.g. Wolff), * common objects (e.g. Stone) But it can result of association of different words (e.g. Livingstone). All that is clear from before, but one can also think that sometimes the original meaning gets lost. So back to Spanish, if Martinez is the son of Martin, Fernandez the son of Fernando, of whom is Saez the son? Linguists and some scholars might know, but the general population does not. And in Spanish, the word for and is y. So consider a tradition which names their children from both their parents (true for last names in Spain): the son of Maria and John could be Mariayjohn, or maybe in some contracted form: Mayjo. Note that instead of names, other inspiration could be taken for combination: a star and a planet, an object and an animal, a place and an animal, etc. Now, one could object that without the contraction it sounds weird, and with it, it seems far fetched. Ask Russian speaking, how they shorten first names. Valerii becomes Valera, and Alexander becomes Sasha. Japanese or similar ideograms-based languages tend to drop one or more of their characters to form nicknames, which would make surprising contraction. Another effect which is observed by linguists could act: people are lazy and tend to deform words to make it easier to say, and given enough time, some mutation may appear. In some languages some letters disappear or some mutate depending on the other words around. So Syng could be an evolution or Syynig stemming from Sylvia y Nigel. And if you give it enough time, people would recognise them as names and not for their original meaning. Only the most curious of us look up the original meaning of their first names. [Answer] You say: > > I'm not asking for people to come up with some weird societal situation; I'm asking from a linguistic point of view. > > > Well, and I’m going to argue that this question cannot be answered without examining societal issues. I’m not a linguist, but still I’m pretty sure that it would be perfectly valid for a language to only provide names with an ‘y’. Why, unless you’re going pretty deep into the linguistics in your writing (as J.R.R. Tolkien did), I think you’ll be perfectly well with just setting up the rule as a characteristic of you language. However: Here come the societal issues. How big is your country? Even more importantly, how secluded is it? If your country is large enough, than most likely inconsistencies are bound to show up. Your language will be divided into local dialects, and some might start providing names without this magic ‘y’. Then, if your country is reasonably open to the outer world, then your language will be exposed to other languages. Foreign words might start appearing, and these foreign words, of course, don’t conform to the rules of your language. People from other countries, even other cultures will start settling in your country; they might have names without this ‘y’. These names may be passed down through generations, and sooner or later may become “normal” or “regular” even among the natives of your country. Still: I think that these rules of your language might be strong enough to withstand all of the above. For example, AFAIK Spanish has something with the ‘s’ consonant, they like to precede it with the ɛ vowel in the pronunciation some cases. If a foreign word violates this rule, then they simply insert this ɛ. For example, they don't pronounce Smaug the dragon’s name or the word ‘snowboard’ like English people; rather, they put this ɛ in front of the word. See Google’s speech synthesizer to get an idea: <https://translate.google.com/#es/en/Smaug> <https://translate.google.com/#es/en/snowboard> Following this idea, your language speakers might start inserting these ‘y’s to any name that doesn’t have them. ## Edit: Following your edit. To my intuition, again not backed up by any serious linguistic knowledge: * A mediaval setting means less communication among different societal groups (no phones, no Internet, few written letters, lots of illiterate people); therefore, in a country of size of Iran I’d imagine lots of different dialects popping up, both based on regions and on societal status. Peasants will speak differently than the aristocrats, and more, peasants from the North of your country will speak differently than peasants from the South. * Even if your country is not a pot of immigrants: what are its neighbours? How secluded is your country from its neighbours? You don't need to be a pot of immigrants to still have some mixing, which is inevitable at least near the border. [Answer] I think it's kind of silly, linguistically speaking. Most personal names predate the invention of writing and come from various sources. It's true that, as Overactor says, some languages have common elements in names that carry meaning, like a suffix -son or like gender affixes in many European languages. But you aren't doing that: the names you list all have the y in different places, and apparently pronounced differently in some cases (I'd assume it's a vowel in "Syng," and just the second half of a digraph in "Theyna"). That seems implausible to me; what kind of mechanism would cause that? Extending it to place names just makes it even worse; often, place names are borrowed from other languages, so there's no good reason for them to all follow a single rule like this. Jane Yolen did this with "kk" in most people's names in her Pit Dragon Chronicles, and I found it a bit distracting there. If you want to provide some connecting factor to the names in a more realistic way, I think it would be better to come up with a short list of the various allowed sounds in their language, how they can be arranged, and how they are written in the Latin alphabet. There might be some suffixes or prefixes that are common, but not universal. You can decide what they mean (for example, "this is a female name," or "Junior," or "this person comes from this place"). [Answer] The most well known canonical example of this is probably that of [Vulcan naming conventions](http://en.wikipedia.org/wiki/Vulcan_(Star_Trek)#Names). Although the rule was never taken seriously and has been clearly been violated. > > The treatment of Vulcan names has been erratic throughout Star Trek's > production history. Early on, female Vulcans were typically given > names beginning with "T" followed by an apostrophe then a "p". The > earliest reference to Vulcan names following a set pattern dates back > to a May 3, 1966 memo from TOS producer Robert H. Justman to Gene > Roddenberry (later reprinted in the book The Making of Star Trek) in > which Justman recommended that all Vulcan names begin with "SP" and > end with "K", and have exactly five letters. (It is clear from the > context of the book, however, that the memo was intended as a joke, as > the series of memos ends up discussing the pronunciation of such names > as "Spook", "Spilk" and "Spork".) > > > Vulcan personal names [actually follow a more complex set of rules](https://kirshara.wordpress.com/2013/03/14/vulcan-personal-names-part-1/) that do not limit themselves as much as this question requires, but it does show a similar linguistic basis. How many people even notice that there were any rules associated with Vulcan naming conventions? To me this seems quite credible if based on some logic (never revealed) that forms the basis for the naming conventions. Vulcans would be very resistant to violating the logical basis for this naming convention. As for the logical source for a naming convention, I would conjecture that it would most likely be related to Surak, the father of Vulcan logic, the greatest vulcan that ever lived. Once a Vulcan demonstrated the infallible logic of personal names to be chosen to honor Surak and the logical basis of Vulcan society, Vulcan names would follow the convention on an on-going basis. This is of course not a linguistic solution, but a cultural one. ]
[Question] [ In this world, mechs (think MechWarrior) have been developed and have become formidable fighting machines. They are capable of dominating the battlefield and can carry multiple heavy weapons into war. And now they are used for sports. The citizens of this world are a bloodthirsty one and watch these mechs tear each other to pieces at weekend events that have become famous the world over. Each weekend a new match is thrown down and only one mech/team remains in the arena. The only issue with this is that the organisers don't want to spend the millions of funds replacing the equipment each week, and the problem with fatal incidents is only growing. A new solution needs to be thought of to preserve the lives of the pilots, the machinery used in the battles and the entertainment of the fans. There have been some attempts to reduce the chaos and death from the old ways, with no success. They are: * Holographic battles (This didn't work as it was obvious to fans that there wasn't any destruction happening) * Remote control drones (A particularly inventive team managed to broadcast a jamming signal to disable the opponent's mech and claim victory) * AI drones (The fans don't have anyone to root for, and it is much less exciting) The requirements are that the battles must be between human pilots and must be live-fire battles. The largest priority is the preservation of life with preservation of equipment a lower priority. What possible solutions are there? [Answer] Reducing material costs to the organizers Make the stakes high enough, and the organizers won't have to pay one thin dime towards the mechs -- the competitors themselves will pay to field them. This is how sports such as NASCAR already work: There's a shiny pot awaiting the winner, but to get there you, not NASCAR, have to buy a car and put a driver in the seat. As you've described it, this is a hugely-attended sport. The organizers are necessarily making an absolute killing from ticket sales, advertising, and broadcast rights. They could easily put some of that toward a ridiculously huge cash pot awaiting the victor, as well as the various other rewards that would necessarily come with being a winner (spokesmech offers, appearances at events, etc.). Get some corporate sponsorship by slapping a big sticker on the mech's side (a la NASCAR cars), and you've got even more of the cost of fielding these things covered. Reducing the risk to life Remote-control is the simplest solution here, short of turning to simulated battles, and actually is not hard to accomplish while defeating jamming tech -- within the confines of a sport, that is. First off, shield the arena itself from EM. This would block any external transmitters from being able to broadcast any signal to any mech. Then, the organizers themselves provide each mech/team with access to a dedicated transmitter in the arena and a randomly-assigned frequency; on fight day, the mech's operators/mechanics would program that frequency into the mech, and then plug the remote controls into the cables that feed said transmitter. Add a few sensors in the arena to detect "rogue" signals from any mech that aren't on its assigned frequency (with immediate power-down of all mechs and forfeiture of the match the consequences of breach of this rule), and you've got a very well-hardened system to prevent jamming. (Spoofing is trivial to defeat: Encrypt the signal between controller and mech. Any signal that doesn't decrypt properly gets discarded (and, of course, logged in case it is evidence of attempted tampering).) For a little extra assurance, the organizers can mandate a "status" signal that the mechs broadcast back toward their transmitters (again on their assigned frequency); any failure of this signal (e.g. via damage to the mech's radio gear, or to the transmitter itself) would be immediately detected by the organizers, and all transmitters promptly shut down while the problem is investigated. A randomly-generated encryption key, provided to the mech's owners on fight day, would prevent spoofing this signal as well as revealing the cheaters trying to do so (and thus causing them to forfeit the match). Do the same thing from the controllers themselves, and now the organizers can even detect tampering of or damage to the cables connecting remotes to transmitters. Add in surprise inspections of equipment to look for any sort of jamming technology, and the risks and costs of getting caught make simply fielding a better mech the most cost-effective way of winning matches and, ultimately, claiming the title of Top Mech. Bonus: Alternative to reduce the risk to life Similar to NASCAR regulations, mandate that pilots be enclosed within ultra-hardened pods. Any damage to/breach of these pods would be considered the "death" of the relevant mech; the status of these pods would be monitored remotely by the organizers, and an immediate "stop" command sent to all mechs on the field once one pod is damaged/breached. (In the case of a team match, the stop might be temporary: The "killed" mech might be removed from the field to save the pilot, and then the match resumed with the remaining competitors.) Additionally, give pilots a "panic button" they can hit if they ever feel they are in danger and unable to safely proceed; this would be analogous to a NASCAR driver leaving the race by pulling off the track, or the crew chief declaring that a car stopping at a pit-stop is unable to continue the race. While they've forfeited this match, they've lived to fight another day in another match. (And as a bonus, the button could be hit in a losing match to preserve the mech itself, thus reducing property damage as well.) There's no way these pods could be designed to be fool-proof, and thus there's still the risk of a pilot being injured or even killed -- just like a NASCAR driver can be injured or killed on the race track. Keeping the pilots inside the mechs necessarily means that they will face this risk; the best you can do is to reduce it as much as possible while still keeping as much of the original "feel" of the sport as you can -- no matter how good the pyrotechnics, there will invariably be people who simply tune the whole sport out entirely if the fights are reduced to simulations in any way. A blood-thirsty spectator demands a blood-thirsty sport, not pretty-but-mostly-harmless explosions. [Answer] Basically, you're designing the mechanical version of the World Wresting Federation meets LaserTag, where damage is fake but the show is spectacular. Instead of real damage to the mech, you have two sets of armor. The outer layer is thinner and can be blown off due to "damage". The inner layer is the real armor that protects both the pilot and the investment. There are ways to make live fire "live" with the necessary compromises to preserve investment. Instead of a true HEAT or AP round, make the munition into pyrotechnics like you'd see at a fireworks display. They're pretty and make a huge boom but don't do much damage. Really high energy weapons such as lasers can simply be tuned down to look pretty. Gauss rifles and other hyper-velocity weapons are just not useful because there's not much for the audience to see so from both the safety and spectacle perspectives, they're not useful. Design the mechs to fail in certain pre-defined ways and with special effects during the failure. If a mech takes enough hits to its arm then the arm falls off in a wild display of pyrotechnics. With enough center-of-mass hits, the mech is disabled and more pyrotechnics. This way, the mechs can be put back together relatively quickly and the huge investment in internal structure, powerplant and actuators can be preserved. NASCAR and Formula 1 are incredibly safe sports despite the very high speeds involved. Mechs could be designed for maximum preservation of the pilot. Indeed, if these mechs are adapted from the military then they have already been designed this way. Accidents will happen of course but make improvements to the mechs and it'll work out. Edit for comment: As @2012rcampion said, you make fake buildings then blow them up for real. Urban settings are still more expensive than outdoor settings without buildings (though you'd need to balance environment effects such as disrupted animal life). Perhaps an urban setting would be a season finale. [Answer] Cloning With cloning you can preserve life, but it might require more advanced technology than you had in mind for your world. First it needs to be possible to make a backup of a pilot's brain and mind. Once you've got that, it needs to be possible to clone a pilot and accelerate the growth of the clone so that the clone quickly reaches the age of the pilot. And finally it needs to be possible to place the backup of the pilot's brain and mind into the pilot's clone after the pilot died. Luckily for the pilot, the backup will be made prior to a fight, so he/she won't remember dying. This approach however doesn't take the preservation of equipment in mind. Though if a pilot can get bonus points for taking out an opponent quickly, then you might also preserve a lot of equipment in most fights. But then again that depends on the pilot's personality. For example, some pilots might be more brutal and cruel, enjoying it to kill their opponents slowly. ]
[Question] [ I read in a paper, posted by L.Dutch, that: > > It turns out that water worlds may be some of the worst places to look for living things. One study presented at the meeting shows how a planet covered in oceans could be starved of phosphorus, a nutrient without which earthly life cannot thrive. Other work concludes that a planet swamped in even deeper water would be geologically dead, lacking any of the planetary processes that nurture life on Earth. > On Earth, rainwater hitting rocks washes phosphorus and other nutrients into the oceans. But without any exposed land, there is no way for phosphorus to enrich water on an aqua planet over time [...] There would be no ocean organisms, such as plankton, to build up oxygen in the planet’s atmosphere, she says — making this type of world a terrible place to find life. > > > But this leaves me wondering, what is the minimum amount of land I can get away with and it be reasonable/plausible, and still be able to give the ocean enough phosphorus to support life. Like, would 10% on a planet 1.5x Earth radii be enough (so around 114764506.18 km2, or 77.37% the area of Earth's land)? Could I maybe just make it low amounts of land and just have it be very rich in posphorus? I want to try to have the minimum amount of land that I can get away with and have a planet that supports life. As it is the next best thing to having no land (like I wanted to, but it now seems that I can't do that without magic, which is very dissapointing). So, I am just trying to see what the expected minimum would be, at least what the minimum amount is that I can go with and it be at least feasible. ## Summary How much land is needed to keep a sufficent amount of phospherous in the ocean as to sustain life, looking for the lower end/minimum amount that I can get away with and it at least be scientifically feasible. As I really want to do a planet with a minimal amount of land, while still developing life. ## Notes * I know you will likely say that I should do whatever I want without feeling creatively constrained by science, and while you are totally correct, I like keeping myself to hard sci-fi. * I didn't use hard-science, but I would still like citations to papers and such if at all possible. It would be much appreciated. * By habitable, I mean that life can develop and survive in the oceans, I do not mean habitable to human and human settlement. I also mean for the water to be habitable, I do not care for land-based life in this scenario, so please do not give examples based upon what would be necessary for land-based life to develop. : ) [Answer] There are many scientists who believe life started on Earth in and around hydrothermal vents. As [AlexP said](https://worldbuilding.stackexchange.com/a/252963/21222), you don't need land, you need a crust. The phosphorous and other chemicals may be brought up from the crust through hydrothermals. However, this will greatly limit the places where life will exist. You may have obly hotspots with very simple forms of life. Life on the surface might be improbable, and a civilization much less likely. If you want to have some landmass, there is no lower threshold in space, but there is one in a combination in space and time. The oceans on Earth were seeded with minerals taken by rivers over billions of years. Less landmass would just take longer to achieve that, and more landmass would get there faster. But depending on the difference in masses we might be talking over as short a span as a few million years to maybe billions of years. [Answer] You don't need any dry land at all. What you need is continental crust. Continental crust does not have to be above water. Here on Earth we have an entire continent, [Zealandia](https://en.wikipedia.org/wiki/Zealandia), which is almost completely submerged, except for New Zealand and New Calendonia. [Answer] We can look into Earth's past for answers: At the end of the Cryogenian Period & It's snowball-earths 720-635 million years ago, there was a spike in phosphorus levels in the ocean, which most likely was a deciding factor for the evolution of animals in the following Ediacaran period due to it stimulating the production of algae. [It has been proposed that](https://theconversation.com/how-snowball-earth-volcanoes-altered-oceans-to-help-kickstart-animal-life-53280) the phosphorus levels might have been caused by abundant underwater volcanism, delivering phosphorus-rich stuff to the surface where chemical reactions would conspire to release the phosphorus into the water. So life on 100% ocean planets seems plausible as long as the planet has enough volcanism and maybe has more phosphorus-rich magma for good measure [Answer] Short answer: There is no lower limit of landmass, it depends on the amount of life you want. Life can evolve without landmass. We know this because when life evolved on earth, the earth was [probably covered by water](https://www.sci.news/geology/archean-earth-ocean-08187.html). I guess you want a bit more life than a handful protozoa. The current marine life consists of [~ 6 billon tons of biomass-carbon](https://ourworldindata.org/life-by-environment). With the amount of land you mention (~77% of the current earths landmass) and minor tweaking of geological conditions (fewer [endorheic basins](https://en.wikipedia.org/wiki/Endorheic_basin), moderately higher concentrations of phosphorous in minerals), maintaining the same amount of biomass should be possible. Keep in mind that the planet you describe has a bigger surface, so it would still be less life per area, but it would probably be concentrated around the continents/islands anyway. If you want smaller landmasses, you could go substantially lower than 10% of the surface. Marine life would decrease accordingly, but probably not die out as a whole (although the "interesting" organisms usually die first). With smaller landmasses, the life would concentrate more and more around the land (and a few hydrothermal vents), leaving the open sea mostly deserted. [Answer] [This NASA article considers some similar questions in the context of the solar system's ice-shell moons](https://ntrs.nasa.gov/api/citations/20220009917/downloads/Glass_2022_Oceanography.pdf). Although it doesn't directly reference extra-solar liquid-surface ocean planets, it does seem to imply that life is likely possible on such planets. On a quick scan, the big challenge seems to be the potential lack of geological activity. If you've got tidal forces, plate tectonics, or similar effects which can cause mixing at the ocean/seafloor interface, then you should be able to get sufficient nutrients into the ocean for life to survive. Note that "tidal forces" are going to be larger when your world is gravitationally bound to a large partner - either a double planet, or a moon orbiting another planet, or an eccentric orbit of a large moon, or something of that sort. A larger world may require a correspondingly-larger partner / driving force to maintain plate tectonics. Also, as mentioned in the NASA article above, strong magnetic fields in a companion planet can induce currents in the ocean world's metallic core (and salty oceans), which can [contribute to the mixing](https://arxiv.org/pdf/astro-ph/0209070.pdf). There's also a "heat of formation" leftover from when planets condense out of asteroids, comets, dust and gas. That's supplemented by the decay of long-lived radioisotopes. [There are some simulations suggesting even deep ocean worlds](https://www.nature.com/articles/s41467-022-30799-2) could sustain enough mixing to support life. If the oceans are deep & cold enough, they'll have ice at the base, but the linked article argues that ice would still allow the nutrient-mixing necessary to sustain life. Also note that there's are two possible ways to look at the criteria for a planet's habitability. One is requiring the planet to be such that life could have evolved there. A contrasting, looser standard is that [life be able to survive there after being seeded from elsewhere](https://www.sciencedirect.com/topics/earth-and-planetary-sciences/panspermia). Although it's possible there's a minimum landmass / surface-percentage to get life, it's still an active area of research. Serious researchers are at least open to the possibility of life on 100% liquid-surface planets. To address your potential concerns about there being interesting, complex, and varied life on the planet, I suggest making the planet's conditions varied in both time & space. Give it plate tectonics, a metallic core and a relatively large moon to help drive a variety of interactions on different timescales. Give it both shallow and deep oceans, ice caps, volcanic vents, subduction, mid-ocean ridges, and other structures that allow different life forms to specialize in different areas of the ocean. Provide multiple energy sources so that lifeforms can specialize in one or the other, or try to shift between them: 1) solar / photosynthesis, 2) geothermal, 3) chemical consumption/oxidation. Energy sources and local life forms will vary by location. Most obviously, photosynthetic life will tend to concentrate near the surface. Read some of the linked articles and use them to inspire the sorts of structures & justifications which fit your narrative. [Answer] Have you read [A gift from Earth](https://en.wikipedia.org/wiki/A_Gift_from_Earth), by Larry Niven? It is set on a planet named "Plateau" > > ... a colony in the Tau Ceti system, ... settled by humans some 300 years before the plot begins. The colony world itself is a Venusian-type planet with a dense, hot, poisonous atmosphere. It would be otherwise uninhabitable, except for a tall monolithic mesa that rises 40 miles (64 km) up into a breathable layer in the upper atmosphere. This gives the planet a habitable area about half the size of California. The Captain of the first colony vessel named the feature Mount Lookitthat (from his interjection at first sight of it), and the colony became known as Plateau. > > > Half a California is 206,000 sq km, or, in more familiar units, $9 \times$ Wales. ]
[Question] [ I’m thinking that there will be one small continent, about half the size of Australia or a bit larger. The single, massive ocean is inhabited by an aquatic humanoid species (yes, think mer-people) that speak to one another in a way that is similar to the sounds that whales make. They do not communicate with the alien species that have settled on the planet’s lone continent via space travel. The ‘land-loving’ aliens have learned that the mer-people (I haven’t come up with a name for them yet) don’t mind them fishing from shore or heavily fortified boats (I might end up changing this to hover crafts of some sort), but that they become hostile when the aliens attempt to swim in the ocean (this isn’t the only reason that the aliens avoid swimming: there are several species of carnivorous, gluttonous leviathans that inhabit the ocean). The mer-people live in harmony with the leviathans, but the alien species are attacked by them on sight (still thinking on why the leviathans leave the mer-people alone). My question is: Where did this continent come from or how did it form on a planet that’s almost entirely encompassed by one massive ocean and how large a human or humanoid species population could inhabit such a small amount of land? Also, if anyone sees anything unrealistic in anything that I’ve mentioned, please let me know. [Answer] It is worth noting that the difference between the deepest ocean trenches an highest mountains on Earth (less than 20 km) amounts to almost nothing compared to the planet's radius (6731 km). It is smoother than a ping-pong ball, relatively speaking. That we have roughly equal parts sea and land (70:30) is a happy accident that has probably aided life on Earth. According to astronomers, [planets totally covered in tens of km of water are much more likely](https://cosmosmagazine.com/space/planets-covered-in-water-may-be-more-common-than-we-thought). Worlds with less oceans are also possible; Mars is though to have had an ocean on its north pole early in the solar system's history, comprising perhaps as much as a third of the surface. What I am saying with this is that a planet with a single, fairly small continent doesn't seem much more unlikely than what we see on our own planet or what we know has been the case on Mars. The continent may be the result of tectonic activity that has raised a 'mountain' above the ocean surface. On our planet, all ground above 7 km is located in Asia, mostly in the [Himalayas and Hindu Kush](https://en.wikipedia.org/wiki/Himalayas#/media/File:Himalayas_Map.png) ranges (which are really parts of the same extended mountain range). If this is the case, expect your continent to be long and narrow, with steep sides. It may also be that your planet has a patch with thin crust, resulting in high volcanic activity, which over billions of years has built a continent. The volcanic activity may have simmered down or ceased by the time of your story. Compare to [Olympus Mons](https://en.wikipedia.org/wiki/Olympus_Mons) on Mars, which rises 22 km above the main Martian surface, covering an area roughly the size of France. This is just a single volcano; with half a dozen such, you could get a small continent. This continent will be flatter than one formed by tectonic forces, and probably more fertile, since that is usually the case with volcanic soil. Finally (though less likely), your continent may be the result of a large comet impact, leaving a huge [complex crater](https://en.wikipedia.org/wiki/Complex_crater), probably a [multi-ringed basin](https://en.wikipedia.org/wiki/Multi-ringed_basin). This will result in several circular mountain ranges and possibly a central peak, with seas in between. [Valhalla Basin](https://en.wikipedia.org/wiki/Valhalla_(crater)) on the Jovian moon Callisto has as radius of almost 2,000 km. [Answer] 1. There was once more land. Your merpeople were originally land dwellers, which is why they are humanoid. Your planet originally had considerably more land, and water tied up in ice caps. With the gradual warming of the planet (greenhouse gas? sun heating up?) there was melting of the icecaps. The humanoids adapted to wetlands, then shallows, then ultimately became aquatic. There is a theory that some human characterists are a result of partial adaptation to wetland / shallows - the [aquatic ape hypothesis](https://en.wikipedia.org/wiki/Aquatic_ape_hypothesis). Take that further. 2. Levitathians are adult merpeople Your merpeople are juveniles in a prolonged childhood. When they go through puberty they grow and become ravenous - the leviathans. These eat too much to live around the juveniles, who would be outcompeted for food, so they go off and live by themselves (like bull elephants or bull whales). They become hungry and huge, and they fight each other ferociously, but they do not become stupid. They do not eat their own kind. This is something which would be revealed halfway through the book when your protagonist realizes 1: the leviathans are intelligent and later 2: they are also merpeople. --- addendum: [Growing up Tyrannosaurus rex: Osteohistology refutes the pygmy “Nanotyrannus” and supports ontogenetic niche partitioning in juvenile Tyrannosaurus](https://advances.sciencemag.org/content/6/1/eaax6250) > > Our independent data contribute to mounting evidence for a rapid shift > in body size associated with ontogenetic niche partitioning late in T. > rex ontogeny > > > A cool thing related to adults = leviathans; T. rex apparently did this, with a huge growth spurt late in life and shift in ecologic niche. [Answer] The continent can be the sole remnant of a large impact with a less dense celestial body. Being less dense, the impactor, or what remained on it on the surface of the planet after the impact, did not sank completely into the body, and remained afloat within the boundaries given by gravity to its maximum elevation. Incidentally, this is one of the proposed explanation of how the continental crust on our own planet formed. [Answer] > > Where did this continent come from or how did it form on a planet that’s almost entirely encompassed by one massive ocean > > > [Continental drift](https://en.wikipedia.org/wiki/Continental_drift) was the theory that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed. But before all that happened, all the landmass was one continent - [Pangaea](https://en.wikipedia.org/wiki/Pangaea). And before the Pangea, there may have been landmasses that came together to form it. It is fair to assume that your merpeople are living in one such world, where the land actually drifts to form larger masses. > > how large a human or humanoid species population could inhabit such a small amount of land > > > Since your planet is earth-like but with smaller "visible" land mass of 10%, whereas Earth has 30% of visible land mass, you can easily have a third of the population of earth at any point of time on the land. Note that this will vary with advancement of technology in society. > > The mer-people live in harmony with the leviathans > > > You could look for reasons such as domestication, symbiotic relationship, complementary lifestyles, mer-people taste rotten :D, etc to build this up. [Answer] You don't have to explain where the continent came from - it's just how the planet formed. Earth had a super-continent - Pangea. The size of the continent is directly proportional to the amount of water the planet has. There is nothing strange in that, it's just natural occurrence. Given the wide variety of exoplanets we've detected, it completely expected that such planets exist. [Answer] One concern I would have is how exactly the merpeople breath underwater. Intelligent animals that live in the our oceans such as cetaceans rise to the surface to breathe, and are well adapted to holding their breath for a long time. But actual undersea animals such as fish just don't get enough oxygen from their gill structures to support the energy hungry brains that provide a platform for intelligence. So perhaps the merpeople have to surface regularly, which of course would mean they need to live near the surface? Perhaps there are naturally occurring air filled caverns replenished by geological processes in which they mostly live? Or perhaps these processes cause massive bubbling throughout the whole ocean and the merpeople's bodies are adapted to capture these bubbles? This could lead to a fun conflict narrative where the land dwellers are mining the ocean and causing a reduction in this bubbling though some sort of fracking process. Or perhaps there is a special plant material that grows all over the ocean surface that eventually sinks, and when they eat it it provides a huge amount of oxygen. Perhaps merpeople, to survive, need to have a backpack full of this food at all time. (Again there is a great conflict narrative there.) As to my last point, perhaps there is some substance in this plant food that when eaten makes them extremely toxic to the leviathans, and so natural selection has caused the leviathans to not eat or attack merpeople. As to where the land came from, I think the idea of an asteroid collision creating the land is excellent. And you could tie it together with the substances in the asteroid mixing with sea water to produce the bubble effect I described above. And the land people who need to mine that material for their own survival are put in conflict with the merpeople because their mining damages their air they breath. It might be interesting too if the giant land mass was in fact composed of a great archipelago of islands so that using the land actually required the land people to use the sea, with, again, the generation of conflict. Just a few thoughts. Sounds like an interesting world. [Answer] I'm a bit late to this but what if the mermaids were similar to lungfish, it would allow them to be underwater long periods of time and go deep while allowing a more complex brain, would also help explain why they would be seen by the surface dwellers: if they were completely dependent on gills and with their size and diet demands they would normally be staying further below the surface only occasionally coming closer to the surface to hunt. They could also have a symbiotic relationship with the leviathans like this one real life human tribe and dolphins, the dolphins chase fish in a cove the humans net the dolphins and fish, give the dolphins their share then let them go been doing it longer than the tribe can remember. It would also help explain why the leviathans get aggressive towards the land dwellers going into the water, they would be feeling like they have competition and need to protect their partners that help them survive from an unknown potentially dangerous creatures [Answer] Mere-folk being left alone by the leviathans. They could have a physical feature which is highly poisonous or distasteful. Evolution's taught the leviathans not to eat them, or simply disregard them as a natural obstacle. There have been several valid answers to your mass of dry land. But if you require another, an impact from a large celestial body crushed its way into the crust, creating a cauldron with sides bending high up in the sky. The impact did its usual thing, melting ice caps and glaciers, ending all land locked life, perhaps leaving interesting artifacts of a long gone era spread across the bottom of a now deep sea. Over the millennia, earthquakes and erotion crumbled the outer walls of the cauldron, making them fall inwards, creating a round valley in which non-nautical life could flourish. Perhaps the bottom of this valley is actually below sea level, opening up the possibility in your story for submersion due to tunnels or cracks in the outer walls. [Answer] Actually, it's a minor tweak. There is a certain, well, mindset that runs around collecting reasons the Earth "can't be" billions of years old. One of their pet claims is the erosion rate of Mt. Everest is some-value-they-quote and then multiply by 1 billion years and get a ridiculous number. They don't keep in mind that [Mt. Everest is also growing.](http://scienceline.ucsb.edu/getkey.php?key=6092) So the net height can rise or fall. If the Earth's tectonic processes were only slightly slower then the amount of land pokiing above the oceans would be substantially smaller. Erosion would carry land to the sea, steadily, bit by bit. Islands would be worn down and disappear. Mountains also would get ground down bit by bit. As they washed into the ocean, the tendency would be for the deeper parts of the ocean to get filled in. This would also, marginally, raise the ocean level as soil disappeared under the waves. [Answer] The unusual planetary geography and the Leviathans/Merfolk are the result of a 3rd party, more advanced alien species. While perhaps a bit handwavy, this is a staple of some sci-fi. Perhaps the island continent was a nasty penal colony at one point, with the Leviathans designed to stop people exploring by boat? Perhaps the entire planet was a research base? Or this alien species were predominately an aquatic species who removed most of the land mass to increase living space? The leviathans and merfolk are left over security and maintenance biological drones, with the merfolk having increased in sentience subsequently. ]
[Question] [ I would like to make mandatory 4 day - 36 hours work week in my beloved [Wadiya](https://worldbuilding.stackexchange.com/questions/75727/how-to-create-a-foreign-legion). Friday is part of the weekend, Monday - Thursday 9 working hours per day. That law should apply to all government agencies & private firms, both domestic and foreign ones. The only ones excepted would be domestic workers, mom & pop firms & construction companies (we are behind in building soccer stadiums & FIFA threatens take our cup). Would the economic effects be highly detrimental of shortening the work week? [Answer] A personal note, for a couple of years I used to work about 40 hours in 4 days, with 5 hours commute on the first and last day. Those four days I had no real life whatsoever, followed by three days of weekend. I could do it but it wasn't nice. A 36-hour workweek is entirely feasible Quite a lot of industrialized countries are worried about the long-term effect as computers displace the workforce from the service sector, just as they have done from industry. Having part of the population in long-term unemployment or McJobs isn't good for society, better use the [productivity increase](https://en.wikipedia.org/wiki/Productivity_improving_technologies) from modern technology to cut everybody a little slack. A 9-hour workday is also feasible Plenty of people work that much, for sustained periods. Depending on what they do, the productivity of the 9th hour might not equal the productivity of the 5th or 6th hour ... # Who gets to work weekends? So now you have everybody at home from Friday to Sunday, right? Well, they'll expect that bakers are open on Friday and Saturday. And grocers. And barbers. Government offices, too, since employed people can't file their tax forms during the working week. Pretty soon you have so many exceptions that the "rule" is more of a guideline. It might apply in the industrial sector, but not in the service sector and not in agriculture. Avoidance Strategies What happens to web-shops? Are they allowed to be open? Would that mean the big internet business has another edge over local shops? Especially if parcel delivery is allowed to work and the parcels can be prepared abroad. International complications It will take some time until foreign business partners get used to the fact that nobody answers the phone for three days in a row. They might take their business elsewhere. [Answer] [Some parts of Sweden are already at 30 hours](http://www.bbc.com/news/business-34677949). So yes, 36 hours are not only possible, but given that both [Norway](http://money.cnn.com/gallery/news/economy/2013/07/10/worlds-shortest-work-weeks/3.html) and Sweden are both countries with high USD per capita and very low working hours it is also reality. [Answer] 36 hours a week and a 4 day work week would not be detrimental; IF emergency services (and a few others) are provided 7 days a week and 24 hours a day. Fire, ambulance, emergency room, police patrols and traffic law enforcement, various kinds of clean-up (removing car accidents from the road, carrying away murdered bodies or cleaning up crime scenes), and some commercial services like burglary alarm monitoring, security personnel, etc. I'd even include weather monitoring personnel, and information system workers to ensure communications are intact. [added: also many military missions must have personnel on duty 24/7; like border watch and missile threat detection.] Both Criminals and the Forces of Nature will work 24/7 whether we like it or not. (and that could be detrimental to your economy.) [Answer] If you're requiring everyone to work the same hours, one big detrimental effect is that everyone who relies on the previous shift would be unable to do their jobs. The hours when businesses are closed are times are when much of the cleaning, maintenance, repair, shipping, receiving, stocking, and processing goes on. Without that, employees who arrived in the morning would be idle until that work was done, businesses would not be able to function anywhere near capacity, and productivity would plummet. Another major detrimental effect would be that the entire consumer economy would be shut down. Since all the stores, restaurants, and entertainment venues (such as those soccer stadiums) would only be open while everyone was at work and couldn't go, no one would be able to spend money and all of those businesses would go bankrupt. Travel, transportation, and tourism would also be affected. Something would need to be done to support all those who previously worked multiple jobs or shifts, or worked nights/weekends because they were going to school or taking care of family. That would significantly impact whatever is in place to care for the poor. Interestingly, your exemptions of domestic workers, mom & pop firms & construction companies, sound like some of the ones that would be least affected. [Answer] You would lose 4 hours of work a week (out of 40, I'm assuming) That is a 10% loss. You would also lose some productivity from the longer work day. Just a guess but I'm assuming another 10% loss. You indicated that you wished to get rid of Friday as a work day. Does this count for retail? Is it mandated that no one can shop or go to a restaurant over the weekend (or just on Friday). Also, as opposed to the 6 hour work day seen in some European countries which lend themselves to 2 shifts a day, shopping would be difficult unless you allow half shifts to part time employees to cover hours so that the rest of the workers can get their shopping done. [Answer] Many factories wouldn't be able to implement it. Right now it's very common for factories to run 24 hours per day, with 3 rotating 8-hour shifts. (A typical pattern is: 1st shift is 7 am to 3 pm, 2nd shift is 3 pm to 11 pm, and 3rd shift is 11 pm to 7 am). There isn't any feasible way to fit a 9-hour work day into this pattern. [Answer] Employers would have to pay more money for same ammount of work. Otherwise is pointless, you would have people with more time but less money, possibly leading to recession. Could employers afford that ? Depends on country. In countries which have lot of natural resources (Norway is one example), they could certainly afford to give various benefits to workers and employers to keep schema going. Countries who need to compete on international market with their products would have a hard time, because shorter work week would make their products more expensive , therefore less competitive . ]
[Question] [ What ways would the scientific/military branch of a (preferably Western) government investigate a foreign object, which can't be moved, in or near a town populated with oblivious people without alerting their suspicion? [Answer] Come up with a cover story and evacuate the area. * In large parts of Europe, this could be an unexploded WWII bomb of specially tricky manufacture, something like a [Tallboy](https://en.wikipedia.org/wiki/Tallboy_(bomb)). The danger radius of those things is large enough to cover a wide evacuation and it would be understandable that the EOD guys work slowly. "We do not want to blow the thing in place, and the alternative is to dig it out very carefully." * Declare that there is a lifestock or plant pest in the area. Nothing dangerous to humans, but the possible economic impact justifies a large quarantine zone. Think back to the [avian influenza](https://en.wikipedia.org/wiki/Avian_influenza). * Or just say "National Security" and refuse to tell details. The press will leap to all the wrong conclusions, possibly terror-related. [Answer] Build a tax inspectors' office on top of it. Easy way to keep the general population well clear of the area. If you want to move lots of heavy equipment in and out then you could build a retail distribution warehouse over it, then nobody would question the trucks coming and going and such things are generically boring. Make sure your scientists work in blue overalls instead of white coats and it's unlikely anyone will notice anything. You might have to advertise jobs at the place locally, interview a few people but not actually give anyone a position. [Answer] I think it depends on four (or more) parameters. Namely the size of the object, the location, the source and the potential risk. The size, location and source are important. People might be able to see what is going on before the government can react. Their cover-up would then also need to explain what people have witnessed. Here is a list of possible ideas. Their usefulness depends on the parameters. They could claim that ... * it is a meteorite or space debris that didn't fully burn during re-entry in the atmosphere * it was a crashed sports aircraft * it was a gas leak * pest control is necessary for that area * radioactive material from a defective radiotherapy source contaminated the area * there was an outbreak of a disease that requires quarantine * it is an artwork by a suddenly famous artist. To ensure that it is not damaged, access is highly restricted * it is a fossile discovered during construction work * it is part of a crime scene that has to be investigated Hope that helps. [Answer] Cover-Up Story Gas leak, sewage leak, or water leak would provide a temporary soultion, but this isn't viable in the long term. There's a better long-term story, depending on the natural resources of the area. Specifically, oil. In almost every country except the United States, the government owns all mineral rights (including oil), even if they don't own the land up top. And by owning the mineral rights normally they can gain access and control over the land up top by eminent domain. The government just needs to create a story that surface oil was discovered which was highly usual given the local geography. Setting up for and then drilling an oil well is a multiyear process, and then even after drilling oil wells tend to provide oil for many years to come. Eventually the government can roll this over form an extraction site to an office location because yada yada. The exact reason doesn't have to make complete sense, after all governments are known for making less-than-ideal choices. What's more, is that oil is typically seen as an interest of national security, so especially in populated areas there would be additional security, which wouldn't really be questioned. Typically while most western countries own the rights to the oil they do work through private companies, so the government will have to strong arm somebody private to this end. Of course the above doesn't exactly work for the US, as citizens who own land own the oil under their land, and the US government can't force them off. [Answer] The object exists yet the inhabitants have no idea of its existence and importance, did I understand this right? The government can just send agents disguised as tourists. Tourists are inconspicuous if they snoop around. One downside could be that the agents' time there is by default limited before townsfolk turn suspicious. Another downside would be if the town isn't the kind of place that attracts tourists. Then they could stage some event, a distraction, to attract outsiders there. Say, a local festival suddenly gains national exposure via a viral video or a UFO has been sighted. Another approach would be to investigate it openly, but under another pretense. Maybe your unmovable object is a hill that's been there ages. A nice story can be that the government agents are a bunch of geologists studying the rock layers because there used to be a lake there during Pangaea or that they discovered a new subspecies of moss and chose this hill to study it because it has the right conditions. The stories should be simple and imply something uninteresting, so they won't attract attention. One of the important things would be for them to appear to pay attention to a much larger area than just the object itself, so no one would suspect there is anything interesting about it. If they're tourists they should talk to the locals and visit the whole town, if they're scientists they should focus on several areas, not just where the unmovable object resides and so on. I say you should take into consideration how many people they need to send there, what kind of settlement it is(large towns are by default easier to receive new people), what kind of information they need to collect (if it's scientific measurements or local peoples' consultation is required), if a construction is required to be raised around the area (they could just pose as a real estate development firm or just a rich recluse, fence the area and build whatever they need) and build your story around these answers. [Answer] First off, I disagree with the "evacuate the area" answers because conspiracy theories are one of America's chief exports and there will always be pesky journalists, scientists, engineers, and Redditors that will try to get to the bottom of the mystery. The only way this would work is if there is some kind of detectable signal, such as EM interference, chemical traces, or radiation, which is often enough to deter people (and in the case of EM, can likely be jammed by the surrounding structure). Anyway, it really depends on the size of the town. If the town is small and remote, use eminent domain to purchase the area of the town for a large federal project, such as a government data center. Say the location is remote enough to be secure for national information security reasons and the to-and-from transportation system helps save the government a lot of money in the long run. Compensate the people of the town squarely, have them resettle in a nearby municipality, and tell everyone there and to be moved there that all of the new government employees will be spending their paychecks in the new town, so on top of a fat check, you will also be offering low-interest loans to spur small businesses that cater to the employees, who might even be working in the [Data Center] and not know it's a front! Locals will be happy to be making money and in time won't miss their old digs in the slightest. The larger the town is, the harder this will be. In a medium-sized city (picking on St. Louis, Missouri for no reason in particular) you can't just expect everyone to up and move, and they will be highly suspicious of a big new building that could have just been built in the suburbs. So instead, partner with a private corporation or holding group to use eminent domain to purchase the necessary tract of land and build something big, like a convention center (which, incidentally, was how my grandfather was forced to sell his restaurant in Rochester, NY). People will grumble but come to accept it, and the flood of people coming in and out for legitimate reasons will keep people from suspecting anything fishy is going on. ]
[Question] [ Discounting the actually quite good idea of having the asteroids be the site of colonization would it be better to use human miners or automated ones? Both would probably deliver the goods by unmanned rockets. Phosphate to the farms on Venus and Mars. Transition metals to everyone. I think simple assaying, mining, and refining A.I. are completely feasible. As are packaging and shipping. So what if any human presence is needed in the belt and why? [Answer] ## Robots, always robots 1. NASA mindset is to kill as few humans as possible Space is dangerous and evil1. Even tiniest error can effectively kill you. Most of the space program is done by NASA and the west. They have the same mindset: Kill as few as possible. It may sound obvious, but during the cold war the Russians had completely different mindset: Get the job done, and if you die in the process, we will celebrate you as a hero. Yes, I know I am exaggerating here, but the point is that as soon as someone is killed in space, people always ask the question: Is space exploration worth it? 2. No one cares about a dead machine If an unmanned mission fails, the info about it barely makes it to first page of news. Mission success? It will be on first pages if it is something really interesting. Otherwise, no one cares. This is extra plus for robotic missions. 3. Caution: Living in space may cause health issues Consult with your doctor before going to space. Truth is, that we really do not know what the long-term effects of being in low gravity are on a human body. We are trying to figure out the effects on human body, and [we are going to find out pretty soon](https://www.nasa.gov/1ym). But one we know for sure: Being in space and mining asteroids will definitely have some effects on human body. We know that it will have also some effects on machines. But we do not care about machines (see point 1 and 2). In nutshell: We are going to use as many robots as possible. I think it is plausible to assume that some humans will be involved in asteroid-mining operations, but the people will be dying. So there will be a moral push to replace them with robots and machines. 1: It does not mean that space it intentionally evil towards anyone. The pure nature of space is that not many live organisms can survive in space without any protection2. 2: And even when being protected, survival in space is hard. [citation needed] [Answer] It's unlikely that a non-communist government would mine asteroids. If private industry found asteroid mining to be cost-effective, then some company would certainly find a way to mine asteroids. That suggests the answer to the question is, "whichever is cheaper". Obviously asteroid mining would have major costs regardless of whether it is done by robots or humans (e.g., delta-v for the mined materials). Robots would be expensive in terms of development, programming, maintenance, replacement, and more subtly, possible lower effectiveness (e.g., programming might never be good enough to automatically find and extract the purest ores compared to a human). Humans would be expensive in terms of life support (air, food, water, and delta-v for the same) and "hazard" costs. Hazard costs depend on whether the pay and/or benefits would have to be good enough to attract human workers to such a risky business, or whether government regulations would require expensive and heavy safety equipment and/or minimum wages and benefits. If asteroid mining could be made to be unskilled labor that can be performed by marginalized, exploited workers who won't demand liability and life insurance, then those workers might have a lower total cost than robots, and that would drive a company to use humans. One likely scenario is that asteroid mining could be like a gold rush where ores are bought for a price and anyone who wants to go get them can sell for that price. It's very likely that after some company builds an infrastructure to mine asteroids, smaller organizations all the way down to private individuals would buy their own mining ships (or mining robots!) and go into business for themselves. Again, the most marginalized might only be able to afford a basic mining ship with a thinner hull (delta-v budget again) and therefore would take higher risks for the chance at striking it rich by staking a claim to an asteroid with great ores. Note that coal mining is pretty dangerous with known, almost-certain, long-term negative health consequences, and yet coal mining is still done by humans the world over. Why? Because those humans are powerless, marginalized, desperate for work, exploitable, and cheaper than robots. At the same time, automobile assembly is much safer than coal mining, and yet robots are widely used to assemble automobiles. Again, in this case robots are cheaper - perhaps partly due to union contracts and government regulations on treatment and pay of workers, and partly because a robot-assembled auto has a more predictable level of quality and interchangability, which lowers the overall costs of making the vehicle. One realistic best-of-both-worlds solution would be remote-controlled drones. The distances involved make it very tricky, though. You couldn't effectively control a drone in the asteroid belt from Mars (best case round-trip communication latency is about an hour). What you could do is stake out a territory in the asteroid belt, find the largest rock in the middle of that territory and put a base there. Have drone pilots stationed at that base, which would still be dangerous, but not as dangerous as human miners actually going out to asteroids and blasting and/or drilling. The drones do the most dangerous part of the work, guided by humans who can bring human intelligence to the process. This saves on programming costs, since you don't have to program the entire process, just the menial tasks. It also saves on liability since you can build one facility to keep all the human operators alive that would be much safer than an EVA suit or a mining ship. Plus you have a one-time large delta-v to get the base set up, and then your actual mining drones could be might lighter in weight so long-term fuel costs would be minimized. Another parallel we can draw from our current economy is that if even one person manages to survive and make a large sum of money by going out alone and finding some great asteroid, others will flock to the belt - regardless of safety. The real winners there will be the companies that build and lease the mining ships - "you must sign a full waiver of liability to lease Exploitocorp's VX-3000 Super Mine Commander asteroid mining vessels". In addition, we would likely have more than a few "mining experts" selling their "Easy 12-step guide to outfitting your own mining vessel and striking it rich!" [Answer] Automatize as much as possible. * Robots are far easier to make radiation-proof and vacuum-proof than humans and can be build for far higher acceleration tolerance. * Robots require no life support in form of oxygen, food, water, plumbing, clothes or hygiene. All they need when not operating is some electric heating or cooling to avoid damage to electronic components. * Robots have no psychological needs which need to be met. They need no time off, no entertainment, no contact with family members, have no personal conflicts with each other, are not annoyed by repetitive tasks and feel no claustrophobia when put in a box for several months. * Putting a robot in serious danger is not ethically questionable (just economically). * A non-return mission which only involves robots is not ethically questionable. * Robotic operations scale almost indefinitely. The number of humans who are physiologically and psychologically qualified for space travel is limited, but when you have the blueprints and the factories you can mass-produce as many mining robots as you need. How much difference these factors make can be easily seen when you consider that it took [a 300 ton rocket](https://en.wikipedia.org/wiki/Molniya-M) to get [a 100kg robot](https://en.wikipedia.org/wiki/Luna_9) to the moon, but [a 3000 ton rocket](https://en.wikipedia.org/wiki/Saturn_V) for [two](https://en.wikipedia.org/wiki/Neil_Armstrong) [humans](https://en.wikipedia.org/wiki/Buzz_Aldrin) of average mass. This simple economic reason is why no human has left Earth orbit for over 40 years. However, there might be a few things which are hard to automatize. When robots break down, there are limits to what you can do remotely. Remote technology controlled from Earth can perform some maintenance and repair tasks, but sometimes you just need actual hands-on treatment by a human technician. Sure, when you have enough robots you can calculate in some losses due to irreparable defects, but depending on how reliable your robots turn out to be, sending a few humans in a pressurized habitat with them who repair any broken mining robots might be economically justifiable. [Answer] If its worth enough for someone to send a ship full of high tech equipment then someone might try and rob the the mined minerals or the high tech equipment. Since that person might not have sufficient funds for his own little army of space pirate robots he will need to hire humans for the job. Now you might be able to have a robot security force on the asteroid but human creativity or level of insanity might be something too complex and hard for an A.I. to comprehend. Therefore you will need a human security force to guard against space pirates. [Answer] Beside from digging rocks, an effective miner has to perform geological surveys, send probes, analyze results, choose the proper mining spots and techniques. The same with refining - you must design and control the cycle depends on materials you got. That tasks could be harder for AI than just sending bore machines in direction some kind of "ore detector" said and then put all the mined materials into some kind of all-round "ore refinery". Can't see any reasons that could not be controlled remotely though. [Answer] Remember [Philae](https://en.wikipedia.org/wiki/Philae_%28spacecraft%29)? If you are seriously going to do heavy engineering, send humans. The lightspeed communications lag will be several minutes and some tunnel bore or smelter running the wrong way that long can wreck your whole day. [Answer] You use humans in preference to robots when robot technology isn't adequate. Most particularly the problem solving aspects when things don't work out as expected (and "as expected" is always a rarity in early days). Since neither technology is adequate right now, it's not possible to answer the question without making presumptions about the state of the technology when somebody decides it must be done. What's specifically wrong with robots right now is that they're dumb and clumsy. If a problem comes up they won't know how to fix it. Even if we upload new firmware they won't have the dexterity to fix it. We won't be able to guide them remotely because of the long round-trip times and low bandwidth for the signal. [Answer] If I had a few\* billion dollars to invest in space mining my action plan would be 1. Find an average\* size rock which can return me good money after mining. It would be economical to risk asteroid than the specially built mining tools, as we have plenty of asteroids. 2. Bring that rock closer to somewhere where it would be easier to mine with remote controlled robots. This can be a moon orbit or even moon surface. ]
[Question] [ In the 2018 movie Upgrade, the quadriplegic protagonist gets a cybernetic neck implant that reconnects his spine and returns his control of his limbs. However, this implant also appears to give him near-superhuman strength (such as lifting another character by the throat with one hand, pushing himself into a backflip, etc). Some of this is probably just film logic, but is it possible that if a computer gained complete nervous control of the human body, it could measurably increase their strength (without modifying any other part of the body)? I was thinking it could force the body to produce more adrenaline or push muscles harder than a human brain would allow, but I don’t know if either of those is realistic. [Answer] It's known that, under special circumstances, people can produce unexpected amount of force, like the classical example of the father lifting alone an entire heavy cupboard when his kid is trapped below it. Therefore an external controller simply ignoring limits could surely push harder. However, that might come at a price. Once I was with my then girlfriend in my car, and it got stuck in some mud in a somewhat remote location: she didn't know how to drive yet and, since I could not push the car and give gas/steer at the same time, she started to panic that we would stay there. This kicked in and she was able to push on her own the car while I was at the wheel. But then in the following days she had severe muscle pain at arms and legs, because of the large effort she had pulled out. Wrapping up, those limits are not there for a caprice of our brain, but are meant to safeguard our own body. Constantly ignoring those limits it's like keeping driving a car while some red light in the dashboard is lit: sooner or later the engine will crash. [Answer] Yes and no. Muscle strength is limited by three variables : * The strength of the bone carrying the force, this is related to the thickness of the bone * The strength of the tendons connecting muscle to the bone. This is limited by the area of connection, which trades off strength for range of motion * The strength of the muscle. Modern human performance at the Olympic or record-setting levels is already encroaching on the limits of the tendons and underlying bones. So, superhuman? Not without some remodeling of the rest of the body. However, it might be possible to “train” muscle strength (within the “human” range) using this technology. Your hero/villain could be surprisingly fit for his or her lifestyle. [Answer] Not really. Hysteric strength is a fallacy whose origin lies in people moving objects that seem heavy, but which have a construction that assists the lifter, such as cars and tractors with flexible tyres and/or suspension, which assists raising part of the object far enough to release a trapped person, who is pinned by a force less than that of the full mass of the object. Things like air-inflated tires, suspension springs or the shape of the object mean that a relatively small application of force alters the dynamic balance of forces enough to allow movement of part of the object over a relatively large distance, but it is by no means possible for the same person to lift a rigid, flat-sided body of approximately the same dimensions and mass. Humans are capable of exerting the full force of their muscles at any time, optimal muscle length permitting. There is little or no 'reserve' where pain prevents maximal exertion, and the body reshapes itself to prevent injury as strength increases due to exercise, thickening bones and tendons. Muscles are not capable of exerting their maximum force throughout the entire range of the motion of the limbs to which they are attached. The microstructure of the actin and myosin filaments is such that muscles work best at around 50% flexure of the limb, when the muscle is half-way between its full extension and full contraction. More extended than that, and fewer of the actin and myosin filaments can engage with each other, and as the muscle contracts more, some of the filaments reach the end of their range of movement and can no longer add to the exertion of the muscle as a whole. There is an instinctive urge to place the limbs in a position allowing maximum exertion when anticipating a need for maximum exertion. This is the reason why in preparation for action in a situation of flight or fight, a creature will crouch, partially flexing its limbs. [Answer] There's a lot of mythinformation (no, that's not a mistake) around the question of hysteric strength, but not all of what you're asking relates to it. Human bodies posses significantly more strength than we are capable of using directly, for a variety of reasons. For instance, electric shocks to muscles can break bones, snap tendons and rip muscle fibers quite badly, something we normally can't achieve by will alone. To be fair much of this is because of abrupt overstimulation of the muscles: direct electrical stimulation can convulse muscles in ways that plain old nerve impulses can't. But there's another aspect to the feats displayed in Upgrade: coordination. The idea seems to be that the control chip was able to fire muscles in ways that would have taken years of acrobatic training for a normal person to achieve. With appropriate programming and control over all of the muscles you could in principle do all sorts of otherwise amazing things. That doesn't give you the ability to ignore the limits of your muscles, but most people would be surprised at how little actual muscle it takes to do a back flip. Most of it is in the technique and flexibility, and it might be a little painful if you haven't spent the time on flex training. But hey, at least you don't have to actually feel the pain since the chip can filter it out. To get actual enhanced strength would take a bit of work however. It would have to infiltrate the entire nervous system to optimize signalling - both latency and signal strength - and you'll need some reinforcement of the muscles (including their anchor points) and tendons if you want to do a lot more with the same muscle mass. This goes well beyond what Upgrade claimed the chip would do. Just bridging broken spinal nerves isn't going to do anything for actual strength. [Answer] Not overnight, no. Others went into the reasons already. However, consider a patient whose body works out intensely during sleep. The machine just does the exercises while the brain sleeps. A computer could, in principle, know and monitor the limits of the body and tailor the exercise to these limits better than an athlete-and-coach-team setup, as to work out more intensely without ever causing an injury. Over time, the body would acquire barely superhuman strength, as in, a little bit stronger than the strongest olympic athletes. So no tearing through steel, but "lifting another character by the throat with one hand, pushing himself into a backflip, etc" sound very plausible, because it is plausible for olympic athletes. [Answer] Yes it could increase the strength,by a lot to be true. I have once made an experimental exosuit on such a principle, so making one faster and stronger by overwriting their musclestrength using electricity. that thing worked, but only for specific movements since the emg sensors would not work due to the high voltage, so a old interface with pre programmed moves and simple methods of activating them was needed. But be careful, while such a thing works, it will also damage the persons muscles exponentially, so it should only be used in extreme schenario's, just like adrenaline does, it can be done for very short amounts of time and up to a specific unknown and variable extend before the muscles damage to badly, or the person dies. So how does this translate to the cybernetic spinal cord? the cybernetic spinal cord might do one of the following things: 1. it increases the voltage and current in ones muscles compared to what it would normally be. 2. it can be hacked more easily to bypass what the body would normally force itself as a limit. this is very realistic since such a system likely would just listen to one specific section of the brain, most likely the conscious side, while the real limiting normally happens more in the subconscious side. 3. it can make them more efficient or fast, if the brain is faster muscles can correct and control themselves faster, in reality this can severely increase ones actual strength and efficiency. and normal efficiency which can also be gained in other way like coordination and/or focus will also make one many times more efficient. if a normal person is capable of largely ignoring pain, has atleast a little strength, and has a high efficiency then they can do seemingly impossible things. most "strong" people now have a deficiency close to 0, look at people getting their strength from practical use or proper training like parcour, or people like bruce lee. the moves you mention would certainly be possible like that, when you look to things bruce lee could do without having that much muscle, just by having great control and being able to ignore pain somewhat, and what parcour people can do, than if you get in somewhere in between, so not even close to any of both's peaks then the moves from the movies are perfectly possible, you just have to find someone like bruce who like the freedom of movement, and/or the show a lot since it is just a showy way of attacking someone, not the most efficient but showy. 4. it doesn't feel pain, or not all pain, or it doesn't send back the pain as well, perhaps it has a maximum amount of pain it can send back, so when the user reaches that it can bypass all the limiting as far as it wants. this would most likely happen due to things like adrenaline, but a trained person might be able to do so without. as a mater of fact there are people in real life who can bypass their bodies limits on bare willpower, often they use some form of excitement/will to replace adrenaline which allows them to go far beyond their bodies limit for quite long in many very small pulses. I know about someone who is does and did so in real life, the things that such people make happen would often sound ridiculous when you where not there to see it for yourself. yet often such people stay quite hidden because often they don't learn to train, and even when being better in something than others many prof teams do not want them, if they notice you are capable of doing it and are doing it, than many of them will not want you in their team, or even want to get rid of you, only if you get famous before they notice will they allow you to stay there. but in general it is seen as a great risk in multiple ways, since such a person often barely has technique so will often look wacky, or just bad in such a thing, they often lose feeling and expression of emotion which makes the sport look bad due to it seeming like someone beats the others by far without breaking a sweat. in fact that is actually true, and that leads to the last point of danger, many of them get physically cold when doing so, their body won't regulate itself properly and will behave it kind of like a body which is half dead, in some cases this can lead to things like the senses dropping(things like becoming temporarily blind, deaf, etc. such people however often don't really notice it themselves in those moments because they only care about what they want), so it is statistically seen very dangerous to the body. most people capable of doing such things are so from young on, almost no one learns it later in life, so most of their bodies can handle much more impact, they often use very short extreme impact forces to make the movements rather than long movements,however sometimes also longer movements with much force. but on a average person who's body is not used to it one such movement already has a large chance of seriously damaging the body. and even such a person can do so quite easily due to operating quite far beyond what the body should be able to do. often they also lose emotion and feeling partly when doing such things a lot which often might make them seem like monsters. but this is also their greatest weakness, many of them eventually seriously injure their body at multiple points, just like someone might do in extreme adrenaline schenario's, but such people don't do so during exercise, or while using their things, they instead often do so when doing nothing, or nothing serious like writing or typing. their body might eventually at random moments not be able to limit itself properly anymore, and so in some moments where it is supposed to be completely relaxed a very small muscle movement instead might be amplified so much that it can seriously injure them, things like ripping a muscle(partly) would normally only happen to people under severe load, to such people such a thing can happen when doing nothing and they might suddenly notice that muscle hurting a lot when trying to use it. such people however often just continue to do things, since they often just care about what they want, and some muscle pain often is not the end of them, soon they will again do such things, and when injured their might even rely on overwriting their body to do normal things. Most people's strength and speed is limited by pain and relaxation of the mind(a average person get's up to around 1/5 the speed of what a decently fast persons brain speed can be, many people get a lot faster in the brain when in stress or adrenaline). by removing the pain and relaxation you can become very strong because the removal of pain makes you strong, the increase of speed makes you much more efficient, and fast(impact force is amplified by speed, this impact force does not only apply to hitting things but also to starting a movement) for the efficiency you can look to a bodybuilder and a old time farmer the body builder has huge muscles but won't really be strong due to a lack of control in them and a lack in speed in using them. a old time farmer might barely have muscle but they can be superhuman strong because they are so efficient with it(and they often have had to endure more pain, stressful (high speed(like falling, having something falling, animals, etc.)) situations which also makes them stronger and faster for the amount of muscle they have. some old time farmers can (almost)litteraly do such things like in the movies, a local oldtime farmer here was called the oak because he could turn his body into oak, that was just by tensening his muscles he could make himself so hard that even the strongest people where incapable of moving him, many such people also could stiffener their finger to be able to pierce right through hard things, later this became a famous movie stunt in karate things, but in reality around here some untrained farmers could do so due to the sheer efficiency they had in the control of their body, and due to the increased reaction speed and relative strength due to things like being exposed to painful situations more. know that if we combine these things where it might overide the voltage and current, increase frequency of the brain(this automatically often gets triggered due to the higher voltage and/or traumatic or dangerous events like a fight accident/adrealine), higher efficiency and coordination, lower pain, or no pain, being able to override pain/or bypas the pain based muscle limiters, and the person daring to do things and learn/try moves. then by combining these things you could actually go far beyond the moves you described, and such things could be considered easy/very much possible. but they are just not the most efficient in a fight, so someone capable might be less likely to use it, unless they just think it is cool and want to do it. to be able to do such things to the full extend you have to think like a kid, or more feel actually since a kid often judges more in feeling than thinking(here feeling is just what feels cool, or what one wants or doesn't want) since such movies are more common now, someone who gets back to such a level is more likely to do it because it is in their mind. however due to society such a person is much less likely to be without any weird things like such a spine or specific events. [Answer] Yes. Although the implants could not actually increase the strength of the person, in theory the person could do a lot more because many limits would be removed. Apparently people can find [the strength to lift cars](https://www.nbcnews.com/healthmain/how-do-people-find-superhuman-strength-lift-cars-921457), so with any issues with fear/fatigue gone, this person could do seemingly superhuman feats. ]
[Question] [ Typically in fantasy, creatures that are infused with fire (dragons, pyromancers, fire elementals, fire-infused monsters, you get the drift right?) seem to be completely unharmed by said fire and its effects (smoke inhalation, deoxygenation, burns from resultant heat.....). In other words, mages and monsters with fire magic seem to give off heat or even have parts of their bodies on fire constantly with no side effects, even starting and shooting fires without getting burned or dying from the aforementioned natural consequences of flame. How is this possible? Magic, obviously, but that isn't good enough for me. Magic in my worlds have rules, right down to how someone can be born with magic powers. This very phenomenon is likely how a fire creature gets it's protection; the spiritual connection they have with flame alters them, much like any relationship affects a person, turning them into what is more or less living ash. That's what I thought would work, anyway. Ash is what's left after a fire's burnt out, so it shouldn't be able to burn, right? And with that fire magic linking body and spirit together even as it burns the body into this incombustible state, surely the organism would survive right? But now I've realized a few glaring issues with this: * Fire causes decomposition, breaking down chemicals necessary for the functioning of a lifeform, so the result, if it was alive, would almost certainly be a form of undead, living through magic alone since magically induced combustion made biological processes impossible * Even if #1 is accounted for, resulting in a living creature with altered biochemistry, the creature will likely still be vulnerable to the smoke inhalation and/or deoxygenation that comes with fire * Natural selection is unlikely to solve the issues above And so my question is simple: How Fireproof Could a Creature Feasibly Become? If further clarification is required, please let me know and I will do my best. [Answer] When you've got magic in play, you're basically talking about one of two schema: passive immunity vs. active management (which can be an unconscious process). Passive immunity is where you find stuff like elementals - which aren't 'alive' in the biological sense, but are instead something already fireproof being given animate attributes through non-organic processes. Biologics that are immune to fire that fall into this category are probably not actually immune to all fire - they're just unbothered by ambient temperatures/atmospheres that the vast majority of fire occurs in will produce. Either the various chemicals from normal combustion are filtered out by their lungs, or they're extremely efficient with oxygen-use, etc. Smoke is an additive to, instead of a replacement for, the existing air - the problem for humans is that the additives bind to our biology and cause toxic effects but if some creature has different physiochemistry it's possible that it simply doesn't process carbon monoxide or whatever. You could probably push such biologics out of their tolerances, it'll just take more than conventional fire (stuff like thermite, etc). Active management is a much more interesting case because this is where your 'human fire mage' becomes immune to fire. Humans, as we know, are NOT fireproof. But when you're able to make fire obey your will, you're presumably also able to will it to go bother someone else. The thermal issue from fire, which causes burns, is a function of energy flow + chemistry. If you can control the energy flow (i.e. make the heat NOT flow into your body) then the thermal issue is completely avoided. This makes sense as a knock-on effect to any magical discipline that involves manipulating fire. Magical models where the power is drawn from the external phenomena are even easier: if you're used to drawing strength from fire, then being exposed to that source means you're able to use what would otherwise be a harmful input to your body as the fuel to redirect it. Active management schemes can be unconscious if, e.g. the magic isn't a skill but rather something you're born with: the same source that gives the power also suffuses into your reflexes and so you regulate your own body temperature as naturally as you breathe, etc. [Answer] As far as dragons are concerned... Although modern dragon myths seem to suggest something else: not all dragons are serving humans in battle! Free dragons use fire against each other when fighting for a mate, or territory. Dragon fire from another dragon does hurt a dragon, but only their belly and eyes are vulnerable. The scales will resist fire. The problem for the dragon using the flame is minor. Dragons only feel the [heat of ignition](https://worldbuilding.stackexchange.com/questions/217828/igniting-a-dragons-fire) shortly.. it won't feel the flame as it persists. The flame is kept on by the dragon, when it spits out fuel. The actual heat - top of the flame - will be at a distance. Bone and scales with asbestos The ignition heat will be inside the mouth. This is very hot, but the palate of a dragon is mainly bone. Scales are bone too. Suppose, dragon evolution has mixed in [asbestos](https://en.wikipedia.org/wiki/Asbestos#Early_references_and_uses), into the bone and teeth.. asbestos is a very common [natural silicate](https://en.wikipedia.org/wiki/Silicate_mineral) mineral, young dragons chew asbestos, to reinforce their scales and bone against heat. [Answer] Fire is not really an issue. Fire never hurt anyone, it's the heat from fire, that's the thing that gets you. And maybe smoke, but I that's more of a problem in a burning building, less when there are fireballs thrown at you. Nothing except a black hole in our universe is immune to heat. If it's not working, you are not using enough heat. Even if your monster is made out of ash or stone, with enough heat that ash can be evaporated, melted or chemically altered to a new substance. So there are 2 questions to ask yourself.1 Can the creature survive this physical or chemical change. 2 How much heat would this change take The second one can be looked up form a table. All materials have melting, evaporation, or reactive points. Just compare it to how hot your fire burns, and you know if the creature can withstand that heat. If on the other hand the creature can survive these massive changes to it's biology, then maybe it's fire proof, but then it's most likely everything proof. A sword is not going to do anything heat can't. Finally you may have fire elementals. These creatures are the embodiment of fire, and heat may just make them stronger. Their biggest issue is they most likely need to oxidize to live. Oddly enough these creatures may ignore heat on their own, but fire destroys their fuel and oxygen. This becomes a real fight fire with fire situation, making fire elementals quickly die if caught in a larger flame. [Answer] # They need a tough outer shell of ash. This is calcium carbonate. It's often used to make cement, so they can have some natural version of this. Calcium carbonate can take temperatures of up to 1000C without melting, and cement 1500C. # They need a heat resistant core. Extremophiles can have functional proteins at high temperatures, of 100C+. With magic, all their proteins could be around this, meaning that heat wouldn't hit them hard. Together, they would be very resistant to quick flames, and take longer for heat to break down. # They also need to be able to use non oxygen respiration You can gain energy without oxygen. They would need to have very acid tolerant blood, and various mechanisms to break down lactic acid and such much faster than we can, so they could rely on non oxygen based respiration. Then, in a flame they could just shut their mouth and nose and not breathe in smoke. A hot enough flame would still melt them, and a sledge hammer could expose the fleshy underlayer, but they could be pretty fire resistant. Enough heat would exhaust them, but they could go without oxygen for a long time. Magic could make these things a bit more efficient. You could have fire magic and mana be some sort of parasite that stole a number of genetic traits from heat resistant creatures and would pass it on to those that mastered fire. They would grow rocky skin, have their biology twisted to become more heat tolerant, and their innards adjusted. A slow disease. [Answer] ## Immunity in high fantasy, resilience in everything else When it comes to high fantasy, most authors tend to equate resilience with absolute immunity. Basically anyone that relies on fire as his main weapon is invulnerable against his own effects, so when two of the same entities meet you basically have an impasse and the only way to resolve the conflict is to use something else, unless someone breaks this standard just for a passing joke. The exception that comes to the top of my mind is from the anime BASTARD!! when the main character fights a demon that's basically the lord of fire. At first the demon is quite arrogant when he realizes the main character also specializes in fire, but fails to realize that the main character is capable of cranking up the heat so far up that even the demon himself can't handle it. As far as low fantasy to medium fantasy goes, I haven't encountered a single example where somebody is completely immune to anything. As far as narrative goes, the more proficient someone is with a certain element, the more resilient he becomes in handling all the harm that originates from that particular element, which means the only two instances when he's in jeopardy is either when caught off-guard or fighting someone who's more proficient with that element. I personally think this is the best way to go and I'm personally using this kind of system in my world. If you are a Fire Mage in world you might be the best when it comes to setting stuff on fire, but if somebody catches you off-guard with a well placed Firebolt to the face you're screwed. Realistically speaking, there are natural ways to adapt to certain elements and develop a high tolerance for their effects. It's down to basic evolution but it requires such a tremendous amount of time that nobody could be sure where that process actually begins, how many phases it actually has and what are the finer details that influence it. The Komodo dragons have perhaps the most toxic bite in the world because of the bacteria cultivated in their mouths (saliva) but they themselves obviously developed an immunity to it, strange underwater creatures adapted to surviving in oceanic depths in absolute darkness and immense water-pressure, water fowl developed unique feather configurations and secretions to keep themselves completely dry and isolated from water even when they're completely submerged, etc. [Answer] Well - for organic entities - the [Leidenfrost](https://en.wikipedia.org/wiki/Leidenfrost_effect) effect. Your fire 'magic' has a basis in physics, and the fuel vaporising forms a barrier. There's illusionists and physisists who have a great deal of fun with it. It would be energy intensive to constantly secrete your fuel/coolant/barrier liquid - but that's probably the price to pay. ]
[Question] [ So, I was thinking. Modern combat relies a lot on intel and speed, but also luck. Now there is a problem. You see, in most video games, even hardcore ones, like Lobotomy Corporation, there are certain safeguards that prevent unavoidable instakill. I'd obviously lose it if Finn or McKenna died on me because of poor RNG. Thus, even against nightmares like Nothing There or WhiteNight, you can use micromanagement to avoid an execution move. But IRL, all it takes is one bullet or complications to do anyone in, yet [some people](https://en.wikipedia.org/wiki/Grigori_Rasputin#Death) can survive seemingly anything. Whether that story about Rasputin was an exaggeration or not, I'm kinda curious, how could the human body be modified to be able to sustain gunshot wounds (up to an intermediate cartridge) pretty much anywhere and live long enough to get at least first aid? We obviously want to maintain a human appearance and the simplest solution usually works the best, but I can stretch things if necessary. Oh, I found this on Quora, btw: <https://www.quora.com/Are-headshots-instant-kills?share=1> [Answer] # Redundancy * Brain stores everything three times, in such a way that you can't draw a line passing through all 3 copies. * Redundant nerves paths that bypass the spine that work when the spine is damaged. * Redundant heart. I'd suggest 2 working at 50% efficiency. * Redundant arteries, which automatically seal when broken. * Larger spleen, holding a larger reserve of blood. [Answer] # Simpson genes Homer Simpson has so much adipose tissue that small cannon balls cannot harm him. He even made a living of being shot for lols at some point. [![Homer taking a canon shot to the belly for lols](https://i.stack.imgur.com/4T848.gif)](https://i.stack.imgur.com/4T848.gif) By the way, this is not cartoon physics. [That scene is based in real life](https://en.wikipedia.org/wiki/Frank_Richards_(performer)). Also, unlike most humans, the bulk of Homer's nervous tissue is just there as redundancy for his two functional neurons. [He can take many hits to the head and still be just as functional as he was before](https://www.youtube.com/watch?v=uxCLsFaK4GA). [Answer] ## You're Looking for Combat Grizzlies If you're looking to modify the human body to survive gun shots, turn your soldiers into Grizzly Bears. With the right google searches, you can find (mildly traumatic) video of a bear getting shot in the face, point blank, with a shotgun, and basically shrugging it off. Bears, man. [takes a drag on the cigarette, stares into the distance.] So what do bears have going for them? * Thick skulls * Blubber * Strong That's basically it. Thick skulls protect the most vital organ - the brain. Blubber protects pretty much everything. And then you have to be strong to carry around all that weight. To survive a large impulse, like a gun shot, you need to spread the impact out over both space and time. Blubber's... blubberiness enables it to do that well. The bullet spends all its energy moving the fat around, and so it doesn't penetrate to hit anything that actually matters. So breed or genetically engineer your soldiers to be huge, with a uniform layer of fat around the whole body, and giant muscles to carry it all. [Answer] From what I understand, most soldiers in war don't die because of guns. Explosives such as landmines or bombs kill the majority. The reason seems to be that the shockwave of an explosion more or less bypasses the Body Armor. So really, if you want fewer casualties, having an effective way to guard against mines is the way to go. In terms of being shot, composite body armor does the trick pretty well. But here, we have a different problem. The round doesn't have to pierce the armor. All of the energy still unloads on your body and can break your bones, leading to massive internal damage. So yeah, you could probably create some sort of composite body armor that stops a .50 cal, but the person would die anyway from the bullet's kinetic energy. You would have to somehow redirect that energy. Something that could do the trick is using body armor that converts kinetic energy into heat. This way, your organs wouldn't get destroyed by the kinetic energy. If the body armor is heat resistant as well, you could have effective protection against high cal guns. But, I have no idea how one would go about building something like that. It wouldn't be cheap. Using implants as armor is a pretty dumb idea too, mainly because the bullet will be stuck in your body (which is bad). You could try your hands on genetic modification as well. If you can create some form of rapid healing ability, most wounds wouldn't be too hard to deal with. Until now, I only talked about Passive Protection, meaning armor that will get hit. Active Protection is not out of the question. Tanks, for example, use Active Protection by launching small explosives at an incoming round, deflecting it in the process. Something like this could also work for Body Armor. Another type would be a gun that is mounted on your back that's used to fire at incoming rounds. So what would be the best solution? Energy-converting body armor is my guess. But, as with all converting, some of the energy will remain as kinetic energy. So, big cal guns will still hurt. Not to mention that the enemy could launch the bullets faster to the point where the armor just melts. You could / should combine that with some sort of active protection though. The gun on the back seems cool enough for that. Needless to say, such armor would be quite expensive, so I'd imagine only Special Forces could use it. [Answer] First, in a very simplified version, a human will die from a gunshot because something irreplaceable got damaged and now can't do its job. So... it's very simple. Make things replaceable and add or change some stuff to make sure this critical jobs of important parts can be fulfilled while the main organ is damaged. For example, micro heartlike pumps controlled with a spinal neural focus point to replace heart for dire situations. Give lungs their own muscles. Normal humans lungs are in an air-tight area controlled with a muscle under this cage. Let lungs have their own muscle tissue around them that will create the necessary vacuum. Secondary neural connection to replace spines temporarily. Regenerating neuron cells, high level root cell concentration in blood. And, an organ to store blood to use in emergencies. What does these stuff means? Well, secondary neural connection thing allows you to walk with a spinal injury because your neurons have a secondary connection that is capable of fulfilling the spine's task. Neural regeneration is crucial because you can now regenerate paralyzed parts. Storing more blood is just a safety measure for immense blood loss. You want someone to walk a few more miles. Not an immortal. Control over the hormones like adrenaline. Second method, high defence. Strong and flexible muscles, strong bone structures, maybe some kind of iron compound to help your boned grow metal. Changing or rearranging the skeleton structure to protect vital parts, A strong skin with perhaps stronger materials to have some kind of an armorlike skin. There was this sea snail that literally creates an armour around its soft tissue. Check for the snail with iron skin. Third method, too distinct. Make your human's body structure way too distributed. Meaning, even if the bullet pierced some vital part, the wound is comparably too small so the organ can keep functioning. For example, a needle sized wound to your hand. Sure, it will hurt. But it won't stop your hand from functioning. Making bigger and possibly compressable organs with high regenerative capabilities can help you survive a gunshot because, bullet is now comparably too small to cause any lethal damage. For example, a bigger heart that is not an organ, but a system now. So, many small pumps that work synchronized? A big brain that stores many things a few more times and maybe spread to neck? These are some ideas I could think of for now. [Answer] ### Make them switch back from warm-blood to cold-blood To keep constant body temperature, mammals spend a lot of energy, and require a higher rate of food and oxygen intake. So we are very vulnerable to loss of blood flow or air intake (pierced lung) that may result from a gunshot wound. Cardiac arrest may cause irreversible brain damage or death in minutes, due to [hypoxia](https://en.wikipedia.org/wiki/Hypoxia_(medical)), if help doesn't come quickly. If humans switched back to cold-blood, our metabolism would be much slower, and we would be able to wait longer for help while wounded. As a bonus, thermal imaging would be useless, easing camouflage and helping to avoid the bullet in first place. That doesn't mean there would be no downsides. People would be sluggish at night and in the morning, just like reptiles and amphibians are. See the Wikipedia articles on [Therapeutic hypothermia](https://en.wikipedia.org/wiki/Targeted_temperature_management) and [Deep hypothermic circulatory arrest](https://en.wikipedia.org/wiki/Deep_hypothermic_circulatory_arrest). [Answer] Stop the bullets from penetrating the skin First engineer things so you skin is made of multiple layers of Kevlar, to stop smaller rounds. Next, you engineer the fat under your skin to act like a Non-Newtonian fluid (the stuff that's a liquid until you hit it and it turns into solid). Which will help dissipate the energy from a gunshot and help to stop the bullet from penetrating too deeply into the body if it penetrates the Kevlar skin. [Answer] * Textwalls incoming * Loose skin * Thick skin * Added shock-absorbtion * Better biological materials added to the skin * Limited redundancies through decentralization of organs A bullet will damage you in two ways. The first is by creating holes, the second by the shockwaves it produces. These shockwaves happen when it's passing through your body in the form of hydrostatic shock and if the bullet is stopped by armor or similar on the outside it'll still create a shockwave propagating through the body. These shockwaves can still rupture organs, bloodvessles and even break bone if it hits it correctly. Any solution will need to solve these problems. Someone already mentioned Grizzly bears, but failed to mention their biggest advantage: Their skin rather than their fat. The skin of Grizzly bears is first and foremost thick by virtue of several layers. It starts with several layered tough hairs with below that several thick layers of skin combined with fat. This skin is also extremely loose, this allows it to survive the biteforce and claw-force of other Grizzly bears as the skin twists and moves along with the forces applies on it. A Grizzly bear is rather large, but we can apply it's advantages on smaller things as well. The Honeybadger famously has the ability to survive bites from Lions and even a strike from the sharp sharp Machete's do not always penetrate their skin. The Honeybadger uses the same tricks as the Grizzly bear: A tough rubbery like loose skin that is thicker than most animals. The skin of a Honeybadger is thicker than most creatures 50 times larger than it. This means that you can retain the human look and don't need to go giant bear-sized creature, although you do have to realize that your human will either need to look a bit oversized or need to be smaller internally. The use of nature's biological materials can add to the strength of the body. For example by placing a few spidersilk Ampullate into each cm2 of the skin you can generate spidersilk strands that are pulled through the skin and reinforce it. The strongest spidersilks can be a magnitude more tough than kevlar, giving you plenty of toughness to withstand bullets if it's distributed through the kin properly. While we think of cells in the body as static, the body is more than capable of letting cells move and migrate, giving you a mechanism to let cells "pull" strands of silk around them and towards nearby cells, allowing you to create a fine mesh of spidersilk through the thick skin. Another advantage is that spidersilk can absorb a lot of force into it as it is stretched. A limited redundancy is much better than a complete redundancy. Using two hearts for example is an often stated advantage in science-fiction and fantasy, but brings tons of problems. If one heart is damaged you instantly lose a lot of your bloodsupply that will be stuck inside and near the heart (assuming it doesn't bleed out). You also have to have systems in place to stop blood from flowing to the damaged heart, which is virtually impossible with the Aorta (and vena cava superior+inferior), redirect it to the still functioning heart, have the second heart be far enough away that it doesn't get damaged as well and since you can't use the Aorta of the first heart you need a second Aorta somewhere else. On top of that both hearts need to be able to pump the full amount of blood around the body in case one of the hearts is damaged. You practically need to double up the size of the entire human just to fit the second heart+aorta. To add a complete redundancy of all organs in the body is absolutely ludicrous! Where are you going to place another brain volume with an exact copy of the connections of the "main" brain? How do you deal with the brain-damaged "main" brain still sending orders down to the body? How do you deal with needing a double nervous system, which even for just the central nervous system means doubling up on brain and spinal volume? A limited redundancy by decentralizing things is much more useful. While some things are hard to decentralize, like the liver, you can still cut the liver into different segments and spread them close around the intestines. The lungs can be compartimentalized, so that if one part of the lung get's punctured the entire lung doesn't collapse or drown in blood but only that segment etc. For important parts in the body you can have extra nerves which combine later on. This is already a taxing idea on the body volume, as for example the nerves in the leg can already be a centimeter thick. [Answer] Make 'em big! > > [How fat do you need to be to make yourself bulletproof?](https://www.thesun.co.uk/news/276919/how-fat-do-you-need-to-be-to-make-yourself-bulletproof/) > > > The short answer is morbidly obese. Science shows that a 9mm bullet > shot from a hand gun can cut through 60cm of fat before it stops. The > downside is, of course, you are more likely to die from > obesity-related diseases than ever catch a bullet. > > > There have been real life examples of body fat saving lives in a gun > attack, however. > > > [![enter image description here](https://i.stack.imgur.com/aS9A4.jpg)](https://i.stack.imgur.com/aS9A4.jpg) ]
[Question] [ So, a few decades after a nuclear holocaust, the people of New Jerusalem out near the great salt lake open up a school to teach people. Since the war, however, technology is gone back to the dark ages, including the ability to mass produce books. My question is, can a school function without mass produced books? The school has about 500 students [Answer] Mass production of books was made possible by Gutenberg's invention. Before that books had to be hand written one by one, making them extremely valuable items. Nevertheless there were schools before that time, mostly relying on oral transmission of knowledge and large libraries where the scholars could copy books needed for research. The very same can happen in your case. [Answer] Adding to the answer by @L.Dutch: not only were there colleges and universities before the invention of the printing press by Gutenberg, but also was the transmission of knowledge from these times kep up for centuries to come. A lecture is called 'lecture' - derived from the Latin term for reading - because the lecturer would read the only available book or script of the knowledge to the students who were to take notes. For this process you do not require any printing press, but paper should be available. The main problem will be the change of knowledge transmission for students who grew up in 'pre-apocalypse' time when barely any knowledge has to be memorised any more, as it can always be looked up online on any smart phone anytime, anywhere, whereas afterwards knowledge has to be meomrised literally, as they can only 'look things up' in the library within their own mind. [Answer] Sure, they can stock places of learning with books the same way they did before there was a printing press: people copying books. Eg. every student copies a book they have to learn twice, verbatim\: once for their own use and the second one goes into the library. And they are learning while they do it. The start would be slow but it would pick up exponentially afterwards. \alterations of course are unavoidable but then, even modern text books have errors in them. [Answer] Depends on if paper is available. For undergraduate level mathematics at least, it is fairly common a lecturer will produce their own online notes for a course rather than assigning a textbook. This is essentially writing a small book. If paper is available, your lecturers should be required to produce such books. Then each student, as part of their degree work, is required to make manual copies of several books. In fact you can pay scribes who are not students. They don't even have to understand what they're copying. Remember the apocalypse was only a few decades ago so literacy is much more common in your world than during the dark ages (for now). Soon you have a respectable library. If paper is unavailable then even students 'taking notes' will be impossible. This is an even bigger obstacle than the nonexistence of a printing press and warrants several questions of its own. Bonus: I don't know how much easier it is to build a paper factory than a printing press. But the university should have its own paper factory and students are required to put in hours to manufacture all the paper they need, or pay extra fees for the labour. [Answer] In addition to all the general answers that have been given about the historical preservation and transmission of knowledge before the mass printing of books, you may want to copy a technique used when books were only somewhat rare: have a group of students share a book, sitting in a circle around it. The students always sit in the same relative positions so each one learns to read best at a somewhat different angle. I can't find any references to this practice online but I remember reading about it in a book about Jewish schools in poor areas of Europe. The same era (or a slightly earlier one) also spawned innovative fonts designed to reduce the amount of ink needed for any given letter. [Answer] The knowledge would be shared via oral stories. And, as consensus is developed for the oral tradition of a given story, it will be written down so the story stays consistent going forward. [Answer] You have a big problem, without cheaply and widely available books you don't have mass literacy any more, add to the lack of availability the fact that it's not worth learning to read when you're struggling to make a living farming without full mechanisation, and the fact that modern acid pulp paper breaks down within 5-10 years under ideal conditions. Taken together all that means that decades after the fall of civilisation you don't have teachers who work from exclusively books any more, maybe some notes but not huge libraries of textbooks. In short no you can't have schools for modern style book learning without books being readily available, pretty much from birth. You can still have training schools for practical skills though, it's amazing what that used to include before computers, including but not limited to architecture, surgery, and advanced algebra & calculus all taught verbally to be done without more than a temporary sketchpad. ]
[Question] [ Orbital Drop Pods are a new-coming part of Futuristic science fiction. Triple A games like CoD: AW and Titanfall feature them as ways to easily reach ground level by cramming armament (such as soldiers or Titans) into metal pods equipped with descent thrusters or shock absorbers to slow the fall. Like a H.A.L.O drop in a tin can. What I'm asking is this: are they militarily sound compared to other alternatives, like the common parachute? What do they have to offer in terms of benefit, or are they just expensive health hazards? [Answer] # Retro-propulsive landing Pros: * Fine control over landing location * Softest landing of all * Cheap re-usability * Potential to land on bodies with little or no atmosphere (mars, the moon) Cons: * Anything near the landing location will get burnt to a crisp * Expensive production # Parachutes Pros: * Cheaper production * Safe landing (unless you happen to end under the drop-pod) * Passive system requiring little supervision Cons: * Unable to land on bodies with little or no atmosphere * Little control over landing location\* * Little potential for re-usability # Hard-landing / Lithobraking Pros: * Fast delivery * Cheapest production * Can land anywhere * Requires no supervision Cons: * Very hard landing, unsuitable for human use and delicate cargo * No control over landing location\* * Non-reusable # Bottom line Considering the above, I'd say each system has it's uses. * Retro-propulsion is best for landing delicate cargo and people in friendly territory on designated landing locations or behind enemy lines for critical missions (too costly to use unreservedly). * Parachutes are a good way to drop cargo or people in a wide area, useful for for large scale attacks or incursions where precision is not essential but numbers are. * Lithobreaking is a practical and inexpensive way to quickly deliver durable supplies such as food, water and certain types of ammunition in case of an emergency. \ Both parachutes and hard landings can be guided with specialized equipment (steerable parachutes and aerodynamic control surfaces) in exchange for an increase in cost and the need for active control and guidance systems* --- If you are asking about the benefits of an orbital drop versus a non-orbital drop, then it simply depends on whether the things you are dropping come from/are manufactured in space. If you need to lift things to space just to drop them back down in the same planet then it hardly has any benefits at all. Unless you have an inexpensive way to get things to space, such as a [launch loop](https://en.wikipedia.org/wiki/Launch_loop), in which case the greatest benefit is speed. [Answer] Always keep in mind that landing method is determined by the cargo. Humans can only survive a certain amount of G-forces (deceleration, velocity change, whatever term you want). Exceed that amount, the person dies. Likewise, equipment can only survive so much. A lump of iron can take a lot more punishment than a person or a computer, but it has its limits. I state this stuff up front because it changes the nature of each drop pod. For Humans, Heinlein gave the best description of a useful, effective pod that I have ever read. It has multiple layers, and gives off chaff and decoys as it falls. Each layer gives a different bit of decelerating technique starting with free fall and just plain taking advantage of the idea of terminal velocity, followed by streamers, then parachutes, and finally Jet braking that were part of the combat suit. The biggest downside is that the element of surprise is pretty much non existant. Once your guys hit the atmosphere, the enemy aware they are coming. The different layers shed off and create chaff so that anything looking to track heat or Radar will have a nervous breakdown. Same thing can apply for equipment, but it can fall faster and hit harder for the most part. Just keep in mind the durability limits of whatever you drop. there may be some things you cannot drop at all and will need to use some sort of shuttle craft for. TLDR; Drop pods are viable and useful, so long as you pay attention to the cargo. [Answer] One benefit to using drop pods for an orbit-to-ground assault is that they are a much harder target to hit than a drop ship. Due to their small size and high entry velocity, it is really hard for AA guns to aim for individual drop pods. A drop ship, on the other hand, would be much heavier (requiring a slower velocity), would be a much larger vessel to hit. Drop pods with individual soldiers or small groups of personnel are also much cheaper and more expendable than drop ships carrying tens of soldiers on board. If the enemy were to shoot down a one one-man drop pod out of a hundred, it would be a much less damaging loss than if they shot down a ship with a hundred people on board. [Answer] It all depends on actual engine technology used. If reliable and cheap enough (better than SpaceX) the benefits, from military point of view, are: * brake at lower altitude (less time being a an anti-aircraft target). * large part of incoming trajectory at high speed (same as above). * last-second maneuverability to chose the right landing spot. * largely unaffected by meteo conditions (especially wind). * possibly a softer landing (no final "bump", dangerous with heavier equipment). [Answer] Where do the drop pods come from? If they're dropped from an orbital platform, like a space station, then logistics are a nightmare. You'd need to keep the station manned with enough combat troops and pods so you can drop them at a moment's notice. The men will need food and the equipment needs maintainence. "Moment's notice" is also a problem. Assuming a low-earth-orbit, you'd probably do one orbit in about 90 minutes. If something happened right after the station left the target, you'd have to wait 90 minutes to drop, maybe more if the target is significantly north or south of the station and you have to wait for things to line up. The element of surprise is not that great either. Even amatuer astronomers can watch the international space station using off the shelf equipment. If any nation on Earth built an orbital platform for deploying drop pods, every other nation would monitor that platform 24/7. As soon as a pod was deployed, its likely landing zone would be estimated. The low orbit also makes it vulnerable to attack. China has already demonstrated the ability to attack orbiting satellites. Even North Korea could probably knock out something like the ISS. Finally, this gets back to logistics, what happens after you drop your super-soldiers way behind enemy lines? Who comes to pick them up? Furthermore, what purpose do the drop pods serve that can't be met with conventional technology? We already have ICBMs capable of hitting any target on Earth within 30 minutes. We can get B2 bombers to any target in far less than 24 hours. What niche do the drop pods fill? [Answer] Something I haven't seen anyone else mention. Drop pods aren't remotely stealthy, it'd be virtually impossible to make them so. So make the problem a feature. Consider the massive element of shock and awe this sort of assault would produce. Sonic booms, streaks of fire across the sky, it'd be the stuff of myth and have an exceptional effect on morale, both yours and your enemy's. The arrival behind your lines of well equipped fresh troops alone is a serious problem that will demoralise your forces. From orbit, you can see the disposition of the enemy, see their emplaced defences and such. If you can place fresh and well equipped troops wherever you want at about three or four minutes notice that gives you a tremendous ability to reshape the battlefield. Comments here discuss the idea of drop pods being deployed from a permanent military facility in orbit as a rapid-response force, that's one option, but depending on the setting that's not the only platform to launch them from. In Warhammer 40,000, Drop pods are used extensively to get power armoured shock-troops into the fight, the doctrine displayed there is to arrive in orbit aboard a large dedicated barge and begin raining pods immediately. give no time to react or respond. For comparison (and the original inspiration for the Warhammer example) Starship Troopers in Heinlein's book of the same name are fired at the planet in individual pods and collected after the fact in dedicated dropships. Those pods arrive surrounded in chaff, flares and ablative plating from their own pods, making it essentially impossible to pick out the trooper himself with anti-aircraft fire. In the Halo franchise, the same concept is applied to the rather tellingly named "Orbital Drop Shock Troopers" In every case I've seen in fiction, Shock and Awe is one of the primary effects and goals of drop pod assaults. I've never read of a pod that arrived using parachutes as its primary deceleration technique. All of them used retro-rockets, sometimes drogue chutes as well. The goal was to arrive as hard and fast as possible without injuring the passengers. [Answer] I'd say it depends on the tech level of the adversaries. Let's drop a pod from orbit... Unless it uses flummoxion-drive antigravity or something, it will have to decelerate using atmospheric braking, like the space shuttle, or retro-rockets ala SpaceX, or both. This means it will get very hot, and become a perfect target for cheap heat seeking missiles. Atmospheric braking works well for fast objects, but once most of the speed is lost, you will still drop like a brick unless you have wings, parachutes, or any other means of propulsion like rockets, helicopter rotor, MHD thrusters, etc. Deceleration needs to occur over a sufficiently long time span to not kill the people inside from G overdose, so you can forget about shock absorbers. So... your drop pod is still very hot from the orbital descent, and now it is slowing down and preparing for a soft landing (since it contains squishy humans) under a parachute. Just fire a [Stinger](https://en.wikipedia.org/wiki/FIM-92_Stinger) or other man-portable air-defence. According to Wikipedia, it costs $38000, but in your near future world it should be cheaper. It is also available on the black market pretty much everywhere. Note this would work day or night... IMO in order not to be shot down the drop pods should aim for a point far enough away from the hot zone, then deploy some wings and fly the rest of the way hugging the ground at low altitude. Add some automated guns to shoot down any incoming missiles... why not. So you get something like an helicopter, more or less. Or an A-10 with a mech strapped under the wing ready to be dropped. Except it has to survive orbital descent, which presents an interesting problem. [Answer] Consider who might be using them, and in what situation. In the Night's Dawn book by Peter F. Hamilton, an opposing force uses the cover and resulting debris from a destructive orbital engagement to seed a planet with drop pods. Since the occupants of the drop pods are supernatural in ability, they only have to hit the surface of the planet to successfully infiltrate it. It's a very large target after all. Obviously this tactic would get significantly harder against a planet that has good defenses, but on a developing, or poorer world this would be most effective. [Answer] Considering that the scenario is on the same planet country vs country: For landing troops from a strategic point of view a very niche use case scenario where you need x heavy armed extremely well trained guns at point C without going through point A and B, in the case of cargo/munition etc sure it makes sense but if you already have troops in the area you most likely control the area and can transport by land or air which would make it cheaper than a drop pod program. Not mentioning ofc the fact that if your troops are surrounded the corect (not ethical\) strategic decision is to let them get captured then try to rescue them rather than sending them munition which might get in the hands of the enemy and just prolong the fight which will end up killing more of your troops. Heavy armored vehicles sorta make sense only if used to move them fast at choke points and surprise the enemy. Planet vs planet scenario:* Most effective way to take the fight to the enemy , landing a full fledged starship might result in being to difficult. So rather than losing trillions of $ in a starship destruction if we lose a few pods/troops at most it will be a few millions . To summarize: For most combat situations drop pods would be absurd both strategically and economically. Not to mention that any anti air defense system would result in heavy loses . Edited\* : Just a thing i forgot : if you have the tech to launch effectively and rather securely pods on X location where most likely there are enemies ... i would suggest dropping some MOAB/FOAB s -like sized bombs rather than risking the life of your troops. [Answer] Let's consider ICBMs as a starting point. Re-entry time from 100kms is 2mins, and speed is typically 7km/s. Until they start re-entry, they're hard to track, as there's no rocket or re-entry heat. (Data from wikipedia) 100kms is obviously way lower than LEO. Two options are possible: * They could be fired from LEO or a higher orbit. A number of other answers point to the high visibility of a retroburn. That may not be a huge issue if you don't know where they're going to land – and because they're hard to track until re-entry, it's not unlikely that the trajectory could remain hidden; I don't think a retroburn would necessarily be enough to make their trajectory known, especially if we try to obfuscate them; I think from an LEO even a fairly small change would have a substantial impact on landing point. Also, just because current reentry methods are very visible, doesn't mean we can't develop more subtle ones. There's never been any need to do so, so I doubt much research has been done. A civilisation otherwise capable of space travel would likely have other options. * They could be dropped from high-altitude space-ships, or even deployed surface-surface via a missile system. In either case, whilst in space, they're pretty safe, as they're hard to spot. We've now got the issue of breaking something from ~7km/s. Wikipedia gives the max acceleration for a human on a rocket sled at 46g. (wow!) Let's take that, and assume that a civilisation otherwise capable of droppods can find a way to reduce the effects of deceleration. We're thus looking at decelerating from 7km/s: 46g = 7000m/s / 152s – so two and a half minutes of breaking at max deceleration. It's gonna have to be rockets; parachutes won't provide that deceleration. Lithobraking will be Lithobreaking, unless we've got some handwavium device to reduce the effects of deceleration – or we're dropping from substantially lower. But, hold on a minute, why are we assuming we're dropping humans, and not combat robots? Suddenly, the deceleration issue largely disappears. We can decelerate a robot very fast (though again, probably not pure lithobraking – very little will survive that kind of impact). How interceptable are these? Hmm... A stinger can be ignored; if that worked, they wouldn't have had to develop THAAD. We can assume THAAD isn't anywhere near 100% effective, as if it were, we'd not care about NK's missiles. Also, it's very expensive per shot. So if we drop some empty pods or similar, we can easily make it too expensive to shoot them all down. Also, how many anti-drop-pod missiles would be available to fire concurrently? We can likely just drop far more pods than can be shot down at once. So survivability is likely to not be an issue. Back to the original question: are they militarily viable? * Currently, the vast quantity of rocket fuel they'd require would make each one extremely expensive, but a civilisation capable of space flight has presumably overcome the fuel cost. * They'd not be stealthy, but given the speed, how quickly a target would realise they were the target and respond is debatable. * It's unlikely they'd be fast-response, due to the time required to plan for their launch and be in the right place in orbit to launch (unless they're deployed by some kind of missile?) TL;DR: So we're looking scenarios which require a planned, but very fast, deployment. Potentially preceded a few seconds earlier by a bombardment (which also might intercept interceptor missiles). Great for any kind of attempt to secure a logistics point (bridge, transmitter, etc) or other asset which wouldn't respond meaningfully in the max ~2 mins warning they'd get. Probably not so great for a coup d'etat, as they're more likely to realise they're being targeted and respond, but still a viable option. If we're dropping combat robots rather than humans, then much more viable. [Answer] Is dropping into the sea an option? Whilst an unprotected human hitting the sea at high velocity is pretty fatal, inside a drop-pod might allow a fairly high-velocity landing? (I've not run any maths). This might be a cheap way to deploy a large number of soldiers at high speed (and hence harder to shoot down). They'd probably have to slow enough that they could be shot down, but if you're doing a large invasion, the numbers would mean that shooting down a sizeable proportion would be problematic. Also, there's significantly less defences at sea. Of course, this means your troops are now deployed at sea, but you could either land somewhere safe and then attack from there, or do a direct sea assault (you'd probably want to drop entire squads in amphibious/submarine capable landing vehicles). Might be an effective way to land troops past planetary defences that might be capable of taking out a few large spaceships, but no use against a few thousand squad-sized drop-pods. Dropping to sea would allow much faster deployment than parachute to land, and the sea would hide them as soon as they go under. [Answer] Depending on what you want to do, laser-powered drop pods may be a good option. [External laser propulsion](https://en.wikipedia.org/wiki/Laser_propulsion) is studied today as an alternate to chemical rockets for launching payloads to orbit, with massive ground laser installations. This is essentially the same concept inverted. It is similar to powered drop pods, but the energy source is a laser battery on the carrier station/ship. It is rather similar to conventional rockets, but the propellant is heated by the external laser instead of an on-board chemical or nuclear reaction. This allows the pods to be significantly simpler, lighter, and more robust as they don't carry a massive energy source that may want to blow up or otherwise fail in unfortunately energetic ways. Obviously, the lasers may also be used for orbital bombardment to suppress, for example, ground defences threatening the pods. Those pods would use on-board propellant for manoeuvring in vacuum, but they wouldn't need a big reserve compared to chemical or even most nuclear propulsions: the laser can heat the propellant up to very high temperatures, meaning that the engine is much more efficient in its propellant consumption. Once in atmosphere (if there is any) and once aerobraking (the "shooting star" phase) is done, they can use atmospheric air as propellant, so they have effectively unlimited manoeuvring range as long as one laser station is overhead. They can even use the drive to get back up to suborbital trajectories for coming back to the station - though they will still need some propellant reserve to finish putting themselves on orbit, as the last burn has to be outside of the atmosphere. This is of course assuming you have orbital superiority (or that it is not a contested landing), but you would probably not want to send infantry if there was still heavy weapons pointed at you anyway. ]
[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/60051/edit). Closed 7 years ago. [Improve this question](/posts/60051/edit) I have a situation where aliens need to pay Earth for something, they don't want to share their technology but they offer any naturally occurring chemical element. Assuming that we'll get 10,000 tons, what kind of element makes the most sense to ask for? Precious metals, uranium or something else? Answers The payment is for the Earth as a whole and goes through UN, they will deliver to whatever address Ban Ki-moon decides. I'm asking what is the most valuable element for Earth. Something that would be useful for us, but either we don't have it on the Earth or it's very hard to extract it. I want to keep things simple so single chemical element in whichever allotrope or isotope we want, as long as it's occurring naturally in our galaxy. No exotic matter, anti matter, neutronium, transuranic elements ... [Answer] Graphene would be a very nice payment - it has a huge range of uses, but it's still difficult and time consuming to produce. 10 kilotons of the stuff would be a massive boon. Helium-3 would also be a very, very nice payment. 15-20 tons of Helium-3 in fusion reactors could power the United States for a year - 10,000 tons of the stuff would keep the US going for half a millennium. [Answer] I'd make a case for Neodymium. It has become indispensable for use as magnets in many electronic devices such as hard drives and smart phones, and [there are already concerns](http://blogs.ei.columbia.edu/2012/09/19/rare-earth-metals-will-we-have-enough/) about whether we have enough of it. [Answer] [Iridium](https://en.wikipedia.org/wiki/Iridium) is an extremely hard, dense and stable element – the most corrosion-resistant metal known, and among the most temperature-enduring ones. It is also a good catalyst. It could conceivably push some technologies a good way beyond what's feasible today, if iridium were available in quantity – but this metal is much rarer than even platinum†. Demand has risen considerably since 2000, and I think it would rise a lot more if the stuff were somewhat cheaply available for a while. This would furthermore not be quite as unlikely as the other suggestions here – iridium is actually not so rare in the universe (as antimatter) or short-lived (as radon), it's just not available for us on earth because almost all of it has sunken into the core in earth's early life. --- †Abundance is actually not the only hurdle in adoption of iridium – the extreme resilence of this metal obviously also make it very difficult to work with. Nevertheless, I think it is a good candidate. [Answer] For scientific study, there are a few substances that would be immensely valuable to science because they are extremely rare/non-existent on the surface, and with half-lives of just a few minutes/seconds/fractions of a second in many cases. Acquiring a huge sample is impractical, so we know little about them. Using the aliens to get a huge sample would help advance science some. [Examples are astatine, radon, and francium](https://en.wikipedia.org/wiki/Island_of_stability#Half-lives_of_the_highest-numbered_elements). If the United States is getting part of the supply, it might appreciate a huge boost in copper, so the [cost of producing a penny can fall below 1 cent](https://en.wikipedia.org/wiki/Penny_(United_States_coin)#Metal_content_and_manufacturing_costs) again, saving a bunch of money each year. Also its useful in electronics and stuff, but think of all the pennies we can make! Or maybe they could take stuff instead? It'd help climate change if they could just take a huge amount of CO2 from our atmosphere using their advanced tech, which would help slow global warming a little. That might actually be the most beneficial option to humanity. I don't know if 10k tons would be enough to make a huge difference though. [Since annual emissions are in gigatons, I suspect not.](https://www.co2.earth/global-co2-emissions). However, maybe they could take 10k tons of spent nuclear fuel instead. [According to this](http://www.nei.org/Knowledge-Center/Nuclear-Statistics/On-Site-Storage-of-Nuclear-Waste), we produce about 2,000 tons of nuclear fuel per year. It'd really help the nuclear waste storage problem if they could take 5 years worth of radioactive waste off the surface and throw it into the Sun for us. [Answer] # Antimatter This would be the ultimate fantasy for any world power. It can be used for both: extremely cheap (almost free) electrical energy for everyone for the next whole century for all people of Earth. It can also be used as the ultimate weapon of mass destruction. Imagine, just 100 grams of antimatter would annihilate with matter in a blast which would be dozens of times more powerful than the atomic bombs dropped on Japan. Basically, antimatter particles are the same as matter, only with opposite electrical charge as the normal matter. It is estimated that at the origin of the universe, almost equal amounts of matter and antimatter would have formed. However, all the universe we can see, is made of matter. Where did all the antimatter go? Nobody knows. [Answer] There's a couple of really good answers we know. ``` 1: Fissile plutonium. 2: Fissile thorium. 3: Titanium. ``` They could pay us in enriched uranium but uranium < plutonium and more expensive to get so why bother. 1 and 2 are a lot of energy available really easily, while 3 is a metal that is worth a lot and won't lose value quickly by becoming more common because it has so many uses. [Answer] 10,000 tons is a lot. Up till now, the world managed to dig up * a total 171,300 tons of gold [(till 2011)](https://en.wikipedia.org/wiki/Gold_reserve) * 60,496 tons Uranium/year [(2015)](http://www.world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/world-uranium-mining-production.aspx) Adding a sizeable share (1/17th for gold, 1/6th of annual production for Uranium) to the market pretty much invalidates the value that is put upon it for the next generations. However, there are materials that wouldn't wreak havoc on the world economy in that large quantities. Among them are iron alloys (1,599.5 million tons / year!), where the effect would be negligible. If you want to keep the world economy intact: take something that we produce arbitrary amounts already. ]
[Question] [ Most questions in this vein seem to center around the inhabitants of a planet moving it. I have a significantly different spin on this idea, though. So, you're a big ball of rock spinning around a star. It's nice. You're getting a nice tan, you don't really think that much because you may have the intelligence of a small animal. Besides, what thinking you do is really slow. Very, very slow. Whatever you use for nerve-type action aren't going to get signals around too quickly. After a while, you start to feel some kind of prickling on your skin. A human might say, "Do I have a rash?" It seems the microscopic (to you) organisms living on your skin are doing quite destructive things to your skin. You might not even be consciously aware of it. All your body knows is there's an irritant, and it needs to get off. Unfortunately, you're a big ball of rock. No thumbs, or even hands. There is a big ball of fire that gives you a nice warm glow on the side facing it, though. Maybe that would help burn this rash off. How do you get there, though? How does a planet move itself through space. I'm looking for actual physics answers here. The best I could come up with is shifting around the center of mass of the planet to (gradually) change its orbit. I wasn't sure how quickly this could work, though. I'm sure it would be really slow (geologic time) by human standards, but I'm sure planets have different perceptions of time. So, the question is, I'm a big ball of rock with a molten core orbiting a star. Earth is a good frame of reference. How do I move closer to the star, even if just for a little bit, to burn this rash off my skin? [Answer] If Mohammed will not go to the mountain, the mountain must come to Mohammed. Your idea of getting hotter is good, the critters are sensitive to small temperature variation, but you don't need to get close to the star to get rid of them. See, the atmosphere you have around your rocky body keeps you warm in the cold of space. Just play with it and cool down a bit. You need to control your volcanoes to give out a lots of gases and ashes, and that will do the trick. You probably don't remember, but when you were young you [did it already](https://en.wikipedia.org/wiki/Deccan_Traps): > > The release of volcanic gases, particularly sulfur dioxide, during the formation of the traps may have contributed to climate change. Data points to an average drop in temperature of about 2 °C (3.6 °F) in this period. > > > Because of its magnitude, scientists have speculated that the gases released during the formation of the Deccan Traps played a major role in the Cretaceous–Paleogene (K–Pg) extinction event (also known as the Cretaceous–Tertiary or K–T extinction). It has been theorized that sudden cooling due to sulfurous volcanic gases released by the formation of the traps and toxic gas emissions may have contributed significantly to the K–Pg, as well as other, mass extinctions. However, the current consensus among the scientific community is that the extinction was primarily triggered by the Chicxulub impact event in North America, which would have produced a sunlight-blocking dust cloud that killed much of the plant life and reduced global temperature (this cooling is called an impact winter) > > > In that case you were helped by that smart guy who threw a ball at you, but if you play hard enough with just your volcanoes you can do it again. As a bonus, you will not lose any mass. [Answer] So you're a rocky planet with a molten core & you want to move? OK then, you just need a big enough volcano & off you go, any big enough volcano will do. You need to time eruptions to your rotation (if you have any) to avoid going in the wrong direction. You may experience some weight loss. > > Or rather (for those who don't understand irony when they see it) you > 'will' experience some weight loss, that's a lot of magma & gas you're > spewing into space. > > > That's unavoidable, unless someone else gives you a nudge there's no other way to move in space accept to > apply the equal & opposite action rule by throwing stuff away from you. > > > And that means shedding mass whatever drive you use, the only stuff you have is you. > > > Of course, there are other much easier ways to change your surface temperature that don't involve any weight loss .. just spew gasses out of your volcanos less energetically (so you don't space any mass) & you'll thicken the atmosphere global warming style, or pump large amounts of ash into the atmosphere to shade the surface & you can have an ice age to kill them off. I'd love to know how your planet manipulates the processes needed to do any of this though [Answer] "shifting around the center of mass of the planet to (gradually) change its orbit" will not work. At all. Maybe if you flex your magnetic field muscles you could interact with the Sun, or another planet's magnetic field. But if you really want to get rid of the icky stuff on your surface, just recycle the surface! a Teensy bit of vulcanism will clear that infection right off! And as a bonus, you soon form new, shiny basalt fields to erase even the last little tracks of the bugs from your skin. [Answer] There are a couple ways a planet could move without building itself a big reaction drive (rocket). How effective they are, though, depends on unspecified details of the planet and solar system. (1) The [Yarkovsky Effect](https://earthsky.org/astronomy-essentials/the-yarkovsky-effect-pushing-asteroids-around-with-sunlight) is an interaction between sunlight and the planet's rotation which produces net thrust. (And here's [what Wikipedia says](https://en.wikipedia.org/wiki/Yarkovsky_effect).) Basically, the day side of a planet is hotter than the night side and emits more IR which produces a small but very real thrust directly away from the sun. If a planet poles point away from its orbital plane, rotation displaces the hot side in the direction of rotation and the thrust from the extra IR will now speed up or slow down the planet and change its orbit. The Yarkovsky Effect is most important for smaller bodies being directly related to surface area, rotation speed and inversely related to mass. But for mid-sized asteroids it is a huge effect which we must take into account in our own Solar System. (It would be a very slow process for an Earth-sized planet.) A planetary being should be able to simulate the YE by moving its atmosphere around or changing its rock color thus shifting the center of temperature away from the sub-solar point or by changing atmospheric reflectivity/emissivity. The key point is to keep the hottest point off center from the dayside. This would be a slow process, but, hey, planets are long-lived. (2) Speaking of long-lived, there's also the Interplanetary Transport Network (It really exists!) The [Interplanetary Transport Network](https://en.wikipedia.org/wiki/Interplanetary_Transport_Network) is a subtle phenomenon produced by the combined gravitational fields of the planets. It's a continually changing set of trajectories which link Lagrangian points together and where an object -- any object of any mass -- can move about with very minor expenditures of energy. (There's no violation of conservation of energy -- the energy is stolen from the other planetary bodes via small-scale [gravity assists](https://en.wikipedia.org/wiki/Gravity_assist).) The only real gotcha is that if the body being moved is large, its own mass affects the ITN's pathways, but this can certainly be taken into account. (For us there's a second gotcha -- the ITN is slow, making it impractical for many uses. But for a planet? No prob.) Combining #1 and #2, I see no reason why a living planet with an atmosphere in a solar system with other planets present couldn't move itself wherever it wanted to given enough time. [Answer] You're correct. You can shift mass around the center of mass in order to move that center of mass over time. It's called [Tidal acceleration](https://en.wikipedia.org/wiki/Tidal_acceleration). The natural tides, caused by the Moon, due to Earth's rotation, are ahead of the Moon and therefore gravitationally drag the Moon, pushing it away from the Earth at an amazingly high speed of 3.78 cm/year. The relevance of this effect in relation to the Sun is doubtful: while the Sun's gravitational pull on Earth is quite strong due to its mass, the tidal force is much weaker than that of the Moon (because distance is more relevant, it's squared for gravitational force but cubed for tidal force), and likewise the torque of the tide bulge on the Sun must be much weaker. If you're willing to give your planet the ability to shift its mass, then it can create non-tidal bulges, perhaps much higher and denser (rock instead of water). But the effectiveness of this approach would never get close to some other answers here, unless you'd be willing to go to the extremes - but then you can as well extend a very long rocky arm to grab the Sun and pull itself closer. [Answer] ## They can and DO. At least, Galilean moons of Jupiter are believed to. See [this preprint](https://arxiv.org/abs/2008.02825) (which was published after peer review, but behind a paywall). See section 3.4 - the moons of Jupiter are heated by tides in their subsurface oceans, when they are in resonance, and this changes the semimajor axis. What I take this to mean is that in theory you could introduce a few milligrams of terrestrial microorganisms into the seas of Europa, make the viscosity of the water change, watch the tidal movement of the ocean drag the moon inward or outward, and have it smash into another of Jupiter's moons, sending out shrapnel in many directions capable of destroying life on Earth ... all by pure biology! It might take some planning (not to mention time) and it might be a very "optimistic" interpretation of the rather hard to fathom content of the PDF, but it seems plausible enough for good sci fi. ]
[Question] [ In the western highlands live the warlike Oelha tribes. The Oelha are infamous raiders left over from one of the hordes that ravaged the land generations ago. Oelha frequently steal cattle and attack outlying villages of the neighboring kingdoms or other clans. While being warlike and vicious the Oelha are also fine craftsmen and metal workers their lands are poor in metal. This means that most of the metals Oelha have go straight into the nobility and straight into swords. The Oelha need some sort of armor to be able to successfully raid further into their neighbors territory since they would come into contact with better arms and armor the further they travel. The Oelha's solution was to make armor out of the trees that surround their homes. What I'm wondering is: would wooden armor cut into scales and sewn together be effective armor? Would wood be able to hold up against weapons common place in the Medieval High Period? Ex: long swords, long bow, pole axe, etc Note: they have access to lots of oak trees [Answer] So, wooden armour did exist in a few places where suitable metal for making arms and armour did not exist. In similar places you might also find bone armour. Here's an example of some aleutian wooden armour: [![Aleut wooden armour](https://i.stack.imgur.com/DvW0d.jpg)](https://i.stack.imgur.com/DvW0d.jpg) Here's a Haida armour suit, with wooden helmet (though they cheated and used leather over the wooden breastplate... may just be decorative, but I'm unsure on that). The Haida had access to some metal (like copper) but nothing particularly useful for weapons or armour. [![Haida wooden armour](https://i.stack.imgur.com/S1ZwK.jpg)](https://i.stack.imgur.com/S1ZwK.jpg) The critical thing there is that metal weapons did not exist either. The amount of wood required to usefully defend the wearer against metal weapons is just too bulky and too heavy. It isn't impossible, obviously... people used wooden shields after all, but shields let you use a much smaller chunk of tree that isn't nearly so inconvenient, and is also easier to make so you can bring spares with you. > > Oelha frequently steal cattle > > > Then clearly they will be using leather and [boiled leather](https://en.wikipedia.org/wiki/Boiled_leather) armour, which is known to work and be staightfoward to make, and would use material that they would already have access to. That's not to say you couldn't use a hybrid design if it better fit your theme... here's a hybrid wood and leather outfit from siberia: [![chukcki or yupik wood and leather armour](https://i.stack.imgur.com/3xejm.jpg)](https://i.stack.imgur.com/3xejm.jpg) These things (as well as having the interesting winged design, overgrown pauldrons that were used like sewn-on shields) could be made from leather, bone, [baleen](https://en.wikipedia.org/wiki/Baleen) or whatever other tough stuff you might be able to get your hands on. It worked for the Yupik and Chukcki, because they lived in cold places and used arrows tipped with stone or bone. As soon as they could get their hands on metal, they used that instead. [Answer] I don't have any evidence backing me up here, but I imagine it would be terrible against a well armed army. That doesn't mean it doesn't have uses. Similar to samurai who had paper plated armor, it would be useful against lightly equip soldiers, small militias or armed peasants. But once you get into the heavy metal armor, shield walls with pole arms poking through and above, and arrows raining down on you, its not much of a battle. The formations used in the battle are going to make it incredibly hard for your soldiers to compete with. As a note, I doubt wooden armor would be 100% necessary. A soldiers behind a tall shield doesn't need the best armor, nor does someone holding a long spear. And as long as you can hit your enemy before they hit you, you don't need to worry too much. Its a fairly fun concept in games. You don't need armor if you never get hit. So as this is your world, your story, you could simply make your Oelha very skilled warriors who engage in small skirmishes, rather than in large battles. Make them take advantage of the land and the terrain. Woodlands to stop cavalry and obscure the vision of archers. Mud and wet ground to bog down heavily armored soldiers. Wooden armor can be made to work. It is better than nothing, but it won't hold much against a metal weapon designed to fight soldiers in metal. [Answer] Go Go Ghengiz Kahn. Ok, so you have a metal poor country. That's ok, you can make up for a lack of metal with other things. Mobility and ranged weapons are what comes to my mind. It's a classic case of if you don't like the Answer, Change the question. On perhaps, if you don't like the probably outcome of the battle plan, make a different plan. The OP mentions access to lots of Oak. Fantastic, it's not the pinnacle of bow making materials but it will serve and it can make excellent arrows. drop some other excellent bow wood trees in the area like Yew or Hedge. So your people are going to be Archers. The qualities of being an archer is going to have a huge impact on your armor design anyway. Next, you mention that they are raiders. Now they could be on foot, or you could have them on horseback. Either way, you don't want them to be over encumbered. Boiled leather would do for most. For those that are more likely to be in combat time after time a wooden scale mail might work. It would be better than nothing. Here is how you could do it. Take each scale and fashion it out of oak. Then wind silk around it, mostly across the grain to help prevent splits, or to at least keep the damaged scale mostly functional if it does split. Silk has the highest fiber strength I can think of for the weight. Then attach the scales to the boiled leather in whatever pattern is effective and that moves with the archer. The fact that this kind of armor may not hold up against a direct attack from a great sword can be made immaterial by staying away from the great sword wielding jerks and shooting the horse out from under them and putting a ton of arrows in the joints of the armor and through the eye holes and such. If you make your archers mounted, yet another whole level of stuff opens up to you. You can get lost in Wikipedia for hours studying the Mongols, the Huns, Scithians and on and on. Just look at light cavalry tactics. Incorporate these ideas to make them influence your armor design, not the other way around. [Answer] First of all: when military were gaining access to iron armor - they were making armor from it. Even fancy looking japaneese armor is a steel lamelar armor (and they are the first when thinking about non-metal armor). Also, they were in position that you describe: low amount of iron. Yet they had to produce protection for troops. Second: wood is made of fibers and split very well. Small lames ever more. Sort of composite stuff would be requred for "scales": plywood, for example. And since we have advanced composite armor, can it be sort of linothorax based? [Answer] I think as long as the design of the armor distributes and dissipates the force of a mass weapon like a pole-ax, two-handed sword, or broadsword, then wooden armor could work. Oak will be strong but its straight grain would be a disadvantage unless it was laminated. Wood Ipe or Osage Orange are very strong and have a twisted grain that makes them resistive to splitting. They dull woodworking tools quickly, so I think they'd stand up to swords, daggers, axes, and maces. Might provide better protection against arrows if the grain was tight and twisted or laminated layers The wooden armor may not have the durability of traditional metal armor, might require repair and replacement of pieces between fights. [Answer] Broadswords, for example are designed for the primary purpose of breaking bones, not so much cutting. A pole-axe when thrust against the chest of steel Armour would slide-off to one side, when swung hard, might break something. Steel armor was designed to deflect ranged weapons, arrows, slingshots. It's not a lot of use against close-range weapons. A sword must be countered with a sword. An early example of a great-sword weighing more than ten pounds: [![enter image description here](https://i.stack.imgur.com/BEzMc.jpg)](https://i.stack.imgur.com/BEzMc.jpg) Attribution - thearma.org This would, when swung by a trained full-grown warrior would crush metal and the flesh beneath at the very least - perhaps the bone too, unless deflected by a sword or other obstacle. Wooden Armour would possess no such advantages of deflection of ranged weapons. A Pole-axe swung might be thwarted by heavy wooden Armour, but the force would still take it's toll on the recipient. Arrows would not be deflected, nor pole-axe thrusts. An opponent could be speared and then finished-off at leisure. Blows from swords: against wood, maybe the force would be spread-out more, if the wooden pieces are sufficiently thick and heavy. Stabbing thrusts could result in the sword getting stuck, giving a surprise-advantage to the Oelha, but then a twist on the hand-guard then further thrust could penetrate and finish the fight. A potential solution to the problem of wood's "splitting along the grain" issue would be binding each "scale" with fiber. Such fibers as are easily processed can be found in nettles, hemp, the cambium of lime trees and aspen - or even cotton could work. (ETA. It occurs to me that animal or even human hair could fit this roll too, the rituals of your tribe may require it.) Your warriors of the Oelha, are going to come home looking like pincushions, but if they possess sufficient skills with their weapons - hopefully intact. [Answer] Wooden armor would be good enough against common bow and slungs. In fact it will be better than steel one, because of smaller weight (and better mobility). But that's all pros. All other medieval weapons would cut and crush wooden armor through. Even old-greek goplite bronze spear and roman pilum would be deadly weapons! But there is a catch. In medieval epochs only small number of warriors had something more than shield and spear: 1. In early medieval (think of viking setting) most warriors had only basic cloth or leather armor. Not everyone had even helemets (even some "poor knights" had only horse, shield and spear (and casual cloth as "armor")). And swords were mostly weapons for battle group leaders (common weapons were spear, axe and knife) and special elite groups (like berserkers) 2. In "medium" medieval (think of "king Arthur" setting) only knights and there battlegroups had desent armor and "classical medieval weapons". They were a key but small part of an army. Garison troops and infantry had poor armor and weponary: helmet was the only metal armor piece in most cases. 3. In late medieval (think of Duma's novel setting) invention of powefull and compact arbalets and first firearms render all but the most heavy armor useless. It lead to division of troops to extreamely heavy knights and cuirassier and light mobile troops with no armor at all (except helmets, may be) - pikemen, crossbowmen, etc. All this mean that in any case your "wooden men" had armor better than most of the opposing enemy soldiers. The only problem for them would be that elite high-trained and high-armed core. To solve this problem they should have good tactics (to cut this core from the rest of ther army), high numbers (compared to this core) and high spirit to withstand great casualties. "Wooden men" would also be good at sieging secondary castles (where there is no or few knights), raiding villiges and towns, destroing economy of medieval states ]
[Question] [ How would a Dictatorship make a country more successful (Wealthy, politically and materialistically powerful, secure, stable)? Background: In this instance the country is a monarchy to begin with. The provinces are controlled by different families who mostly do what they want... all of them have control over specific elements in the economy. Like the one family controls the Navy; another controls a large percentage of the country's produce; another controls the Banks. The Monarch is basically in place to give everyone a power check and keep the country united. He is overthrown by the Family that happens to control the police force (but not the army, which is unprepared and not very large). The obvious answer for the benefit of a dictatorship is that the country is united behind one leader. An important characteristic in this situation however, is that even after the change of power, the Families would still have some power... Definition: Dictator - a ruler with total power over a country, typically one who has obtained control by force. \* Note that this doesn't state that the Dictator is cruel or tyrannical. The common people actually aren't treated worse than before. The main difference is among the higher ups, like where the money goes and who has the final say in decision and international policy. [Answer] A well-run dictatorship is superior to any other form of government. Well-run dictatorships are unicorns though, since most of the goals I'm about to list are the exact opposite of what dictators are aiming for. Why can a dictatorship be great? Because you can ignore special interests and other inefficiencies. You can remove corruption. You can invest heavily in the future without worrying about temporary setbacks. You can engage in long-term planning. You can make decisions quickly. Special interests and other inefficiencies. You said that one Family controls the Navy, one the banks, one the produce, etc. That sounds like your entire nation is a series of monopolies, which is probably inefficient. Use your dictatorial powers to open up the field for competition. Allow the free market to improve productivity. Remove corruption. Ruthlessly execute corrupt officials and strip their family of all assets. Make it so that the rewards of corruption aren't worth the risks, and you'll find your nation operating more efficiently at all levels. This one will actually affect the lives of normal people - imagine a medieval peasant actually being able to trust the police. Invest heavily in the future, ignoring minor setbacks. Build those infrastructure projects. Educate your populace. Invite foreign investment and make sure that they have sustained legal protection so that even more flows in (no "nationalizing/stealing" foreign assets.) Use your stability and vision to forge economic alliances that boost your economy and open up markets for your corruption-free, open market industries to compete in. Fund research and exploration. Be prepared for war even when peace is long-lived. You can make decisions quickly. In a democracy, even the most sensible decision can take time. The dictator can cut through red tape, can issue direct orders, and can bring the nation to action as fast as his commands can be distributed. An okay decision today is often better than a good decision a year from now. The best example I have here is Pinochet from Chile. Pinochet was no angel - he killed/disappeared thousands of people (many of whom would be considered innocent). But the general consensus is that he managed to set Chile on a path that has made them the best nation in South American by almost any economic measure except equality. Even there, the modern Chilean poor are better off and less numerous than the Chilean poor when Pinochet took power, so judge carefully. [Answer] In your specific case: In your case, I think the new ruler is a new monarch, not a dictator. The new ruler doesn't have enough force or influence to rule with absolute power. Any of the other families could depose this new ruler in a heart beat. So I don't think they qualify as a dictator, unless one of the major families allies with them. The problem is as follows: Army beats* Police Force.* Bankers +* Money + Mercenary Army beats Police Force.* This specific scenario might make more sense if it was the army that took over and seized the whole nation. Or some group that can leverage extreme force. In general: That said, the ancient Greeks thought that a [benevolent dictatorship](https://en.wikipedia.org/wiki/Benevolent_dictatorship) would be one of the most ideal forms of government. [They theorized many different ways to make this happen](https://gimmesometruthblog.wordpress.com/2014/07/17/did-the-people-of-greece-prefer-tyranny-to-democracy-2/#_ftn17). But basically if you have a dictator who wants the good of their people, there are a lot of things they can do that traditional governments can't. Income inequality, lack of jobs, civil rights abuses, almost anything can be solved with a hand wave and overwhelming force. The problem is not having a benevolent dictator, the problem is that the people who tend to become dictators are not benevolent (usually traitors to begin with). And second, even if you get a benevolent dictator, as there have been in history, once they pass away their is no guarantee that the next person will be benevolent. [Answer] A common effect of political fragmentation is the imposition of economic barriers. Each subsection of the realm will institute trade barriers such as high tolls for transshipping goods, and possibly tariffs whose intent is to increase the prices of imported goods and make them less competitive with locally-produced products. The practice occurred, for instance, in many of the original American colonies. This has a very bad long-term effect on the larger economy. Successful economies generally encourage specialization, with trade to distribute each specialized areas goods to the others. It's entirely possible for a dictator to eliminate these barriers to the free flow of goods. This will have excellent consequences for the economy as a whole, although not necessarily for any particular realm. Depending on the smarts of the dictator, it's also possible for him to institute (at least partially) a command economy, with resources devoted to projects with long-term payoffs which would otherwise not occur. An example might be investment in civil waterworks and piping, which will provide clean water to all, with an attendant drop in disease rates. Of course, none of this is guaranteed to succeed. As the saying goes, "Power tends to corrupt, absolute power corrupts absolutely." This will apply to the dictator, and (importantly) to his advisors. Corruption in the application of otherwise well-intended projects can easily offset any benefits, and in the worst case produce a kleptocracy. This pattern is widely seen in third-world countries today. [Answer] The intent of this answer is not to glorify evil in any way. I simply wish to state some truth. It is true that Adolf Hitler did many evil things and I don't want to make him sound good. but it is also true that Germany and its allies got terrifyingly close to taking over the eastern world. Only were they stopped by a coalition of the greatest forces in the world and some battles won barely dangling by a strand. This occurred because of the dictatorship of Hitler. I suggest to find more information about this look up things like "how was Hitler so successful?" or "why did Hitler accomplish so much?". I can provide more information myself I just do not have the time to do so at the moment but leave a comment if you would like me to expound upon this answer. [Answer] After about half a century of attempting to absorb information about history and feeling I may have acquired what Oscar Levant referred to as a smattering of ignorance, I feel it possible, when evaluating the potential effectiveness of dictatorship, we may lead ourselves into an intellectual corner by the use of the word "absolute" when discussing the nature of dictatorship or what is referred to often as "absolutism". I am left with the impression that no matter how effective a given individual has been in consolidating power, it is never literally "absolute". It is always dependent on factors that are essential for the acquisition and maintenance of the power, more often than not the interested loyalty of what Alexis de T. called "the organized adolescents of the world known as the military class". In some cases it may depend on having a wife who will not poison you or a Praetorian guard who will not slit your throat in that tunnel up on the Palatine Hill or having a populace that will tolerate the autocrat. There seem always to be important and essential factors that limit an "absolute" autocrat, beginning with the degree of the individual´s competence/incompetence. (The last Czar of the Russian Empire is a good example.) I can think of a myriad of other examples, but, I recognize the degree to which my opinion may be well-received depends on not going on at length too much. Suffice it to say, my point in answer to the question posed is that the success of any dictatorship (in the eyes of those of us who would judge him/her benevolent or tyrannical) in making a country successful, depends, in the first instance on what you mean by a successful country, (a Switzerland or a Norway or some totalitarian state that has temporarily defeated its competition, North Korea or Venezuela, perhaps.) In the second instance, when a dictator is involved, it depends on the degree to which the dictator either cows opposition (using, deceit, intimidation, fear of violence or the use of it) or placates it, (using bread and circuses, munificence, permissiveness, public works, easy credit and other bribes) and uses scapegoats for whatever does not placate the unruly masses and whether there exist factors or institutions that limit the power. A good study on this is Rome under Augustus, the Pax Romana. (See, Stark, Rome on the Euphrates, page 149, "Augustus´Handling of Power" and page 153, Tragedy of the Facade".) If this makes sense, then, to judge success, after defining what a successful country is, I suggest we may need to look less at the manners and mores of a putative dictator and examine closely his/her methods and the available factors that limit the exercise of the power. In the ultimate instance, it is the results that count and, looking at history, one might conclude that no dictator can make a successful country unless, over time, he/she becomes less and less of a dictator. [Answer] ## It's impossible because the intention to seize totalitarian power contradicts the intentions to do actual "good". Let's take a more libertarian/philosophical approach. The types of relations humans can have are essentially this: * Based on (continuous) negotiation and reciprocal benefit: "We both agree to benefit each other, and we both are free to stop." * Based on power with winner and loser: "Obey or suffer the consequences. I command you, and if you refuse, I will destroy you." What must a dictator be as a baseline in order to be a dictator before even actively "doing" anything specific? * He must be willing to invoke taxes on all people he has control over. * He must be willing to exert force and coercion over people who refuse to pay taxes or comply with his laws and demands. * He must be willing to hold, perpetuate and benefit from a collectivist ideology, which promotes state power and the foundational idea that it is just and reasonable to initiate violence against people for the sake of the *higher good. Along with that, he must be in opposition to individualism - he must be convinced that he can micro- and macromanage people (and the economy) better than they themselves, and that individuals would just "waste" their freedoms for things he doesn't deem useful. * He must be complicit with the idea to hold power as centralized, undivided and undeluded as possible. The magnitude of course matters - the same ruler could either starve its citizens or just take less from them. But the practice in essence is the same - and if he doesn't take enough, he can not be a dictator. So let's assume a high magnitude. --- So - the question boils down to this at this point: What can a dictator, who is already exploiting and oppressing its people en masse to a large degree, prevent his economy to collapse too rapidly? A significant correlation is this: The more individual liberties (free speech, property rights) and economic opportunities (less taxes, less restrictions), the more economic success and prosperity. And for the sake of definition let's say that is actual "good", along with having ethics, internal peace, more negotiation based relationships, less power based relationships. Let's not expand on the reasoning, but let's assume it is true - can a dictator ever go towards these goals without ceasing to be a dictator, without removing himself from the power he once desired and succeeded to seize - or likely intends to hold as he might claim to "fight corruption" (which often is the result of special state and big corporation interactions in the first place)? The answer is no. One would have to fight his own beliefs, his own being. --- What can a "benevolent dictator" do? He can pursue planned economy or economic fascism. The best case scenario is that it works out on the *short term* - and as such probably even tremendously, mustering massive resources for war and major social plans - but will fail on the *long term*. "Success" would be merely temporary. Also it causes major issues which slowly and inevitably lead to internal and/or external conflicts and issues - rendering the system and the regime highly unstable. Getting rid of "corruption" is also a questionable goal if state power is the soil it depends on, which is maximized in the first place. It's more likely to replace one type of corruption with another type (which can be just a different type of unethical practice). Besides, if there is a regime which has a structure set up to serve the will of a benevolent dictator, it wouldn't be too difficult to replace him with someone who is more fitting to such a position of power - who would no longer be "benevolent". [Answer] A few good things can come from Palace coups d'etat. The most important are the churn in key personelle, if the new decision makers are competent, and the need to buy up popular feeling, which might lead to pay increases, redistribution of land or grain, the sacking of the outgoing title holders to pay promises to supporters, and perhaps reformation of banking and land title law, rental caps, employment incentives. The bad aspects of dictatorships generally outweigh the good. The personalities of the Junta, in order to pursue absolute power, are not at all considerate or sensitive, but rather, murderously egoistic. They are schooled and experienced in the emotional realities of dominance/ submission, and unlikely to engage in negotiations toward compromise, let alone collaboration. Avoidance of conflict is not on their radar. Any good good that comes of them, with rare exceptions, is not by their own conscious design. The success of the nation resulting from the coup d'etat could be the result of new personelle bringing creativity to old problems, and also from a freeing up of social mobility , at least for a select group. New business deals and management strategies from new relationships, with an aura of new beginnings, could perhaps create business optimism. Rewriting of the official narrative, (ie, the deposed group will now be depicted as bad), could make many people more energetic for psycho-emotional reasons, as anyone who had sufferred under the last regime can speak out and direct their anger toward the past, also giving an aura of positive change. ]
[Question] [ I'm not sure if it's even feasible, but I have a server farm in my book, of a size that puts it on par with Google's. I want to wipe out all the data stored on the hard drives, without destroying the servers themselves, most likely using an EMP device. This is assuming the device is within the farm itself, basically an emergency wipe. An example data center is [Pryor Creek](https://www.google.com/about/datacenters/inside/locations/mayes-county/) (Mayes County), Oklahoma , 980,000 square feet. Google, for security purposes, doesn't release a lot of data. Let's say at least a few hundred thousand servers, as that matches what I have in my book. If this is possible: 1. What sized capacitors would it need? How long would it take to charge said capacitors? 2. What are we looking at for coils? I've read 10-12 coils of copper tubing would create a rather massive field. If it is not possible, I'd have basically the same questions, but for destroying the server farm. I'd prefer to leave the hardware intact, but can live with it if not. Another idea beyond EMP would be welcome, as well, if an EMP device were not feasible. If this is the case, it would have to be something that is hidden from all the techs working on the farm, installed in secret by an extremely small team in the case of emergencies. Effectively, the owner(s) want a secure way to instantaneously wipe every bit of data stored on the server, hardware based and in no way connected to the system. A kill switch. Better if they could kill it without destroying a farm's worth of servers. [Answer] An EMP is probably not the right mechanism here - it will almost certainly result in large amounts of the precious smoke escaping from the sensitive electronics in the servers (and drives) but assuming it's a typical google data center then the bulk of the data is going to be stored on [spinning rust](https://www.datacenterknowledge.com/archives/2016/05/02/google-wants-rethink-data-center-storage) and therefore will likely survive. It will be difficult, expensive and time consuming to recover since you'll need specialist forensics experts working on it though so this might be "good enough" for your purposes. What you want is a pulse [degausser](http://degausser.com/) - basically these create a rapidly alternating, incredibly powerful magnetic field that demagnetizes the drive platters rendering it an unrecoverable paperweight. The drives will have to be replaced afterwards (technically the manufacturer could recreate the servo track to make the drive re-usable but it's probably be cheaper just to buy new drives!) but the majority of the other components should survive. This though does have the opposite problem to the EMP idea - SSD drives and other flash-storage technology will shrug it off so you'll need to have an alternative strategy in place for those. If we're into the realms of money being no object then a bespoke setup where each SSD was mounted in a modified version of [a crusher like this](https://www.veritysystems.com/products/crunch-250/) would do the job - again the drives will be toast but there's very few other ways to destroy an SSD securely in rapid fashion, and 9 secs is going to take some serious beating. Edit: Just seen an update from the OP on criteria. > > What I'm looking for is a hardware based solution to wiping out all the hard drives that's not likely to be detected by people working on the hardware. Software could, and would in the context of the story, be found and purged. > > > If secrecy surrounding at least the existence of the "fail safe" hardware prior to the "wipe" is required then the degausser option would still work - build it into the frame of the racking, sure it'll look a bit more robust than your average server rack but the owners could fob any questions off as it being for "Earthquake hardening" or something. Obviously post-wipe anyone with access to the drives is going to know what happened - a complete lack of data and the telltale demise of the servo track is a dead give away that the drive has been degaussed. It does make any SSD drives more difficult to deal with though - crusher devices aren't exactly svelte and most techs are going to wonder why the "drive enclosure" for each SSD drive is a 12" or so tall. So for this I'd suggest a slightly different approach: Have all data on the SSD drives be encrypted with something along the lines of AES, keep the key for that encryption on a separate drive that you keep out of the path of the day to day techs that is located in a crusher. When the fail safe is triggered you have key drive crushed at the same time as terminating power to any systems with the key in memory. With the key gone the SSDs are left perfectly intact (saves on your BCDR budget a little bit :P ) but the data is, to all intents and purposes lost. If you're wanting to use the EMP for The Rule of Cool you could have that take out the systems that have the key in memory if you want :) [Answer] Small and easy! Every piece of data stored in Google is actually split into multiple chunks. Each chunk is encrypted using a different key! That's a lot of keys? How are they managed? Well, there are Key Management Servers (KMS) that take all those keys and encrypt them to ensure they are safe. Of course, the keys used to encrypt these keys also need to be encrypted. This goes until you get to the Root KMS key. This key exists on only a few machines in the datacenter... and if you can take all of these out (keep in mind, resiliency is built in by design) then nobody can decrypt any keys underneath it! All the data is still there, but meaningless and lost forever. This is similar to @nzaman's thinking, but already done, only requires impacting a few machines rather than every machine. So it's not the size of the bomb, but the location(s) that makes all the difference. <https://cloud.google.com/security/encryption-at-rest/default-encryption/> Or is it? Google isn't silly enough to trust all its keys to a single data center. There is always a risk that some massive power outage etc. would compromise the keys (stored in memory only) and losing that data would be disastrous. So there are two fail safes: The Root KMS Master Key Distributor, essentially a P2P backup with other datacenters: > > Root KMS in turn has its own root key, called the root KMS master key, which is also AES256 and is stored in a peer-to-peer infrastructure, the root KMS master key distributor, which replicates these keys globally. The root KMS master key distributor only holds the keys in RAM on the same dedicated machines as Root KMS > > > And the Safes: > > To address the scenario where all instances of the root KMS master key distributor restart simultaneously, the root KMS master key is also backed up on secure hardware devices stored in physical safes in highly secured areas in two physically separated, global Google locations. This backup would be needed only if all distributor instances were to go down at once; for example, in a global restart. Fewer than 20 Google employees are able to access these safes. > > > Now whether or not these backup strategies exist in your world, or can be avoided through other means (e.g. more than one 'bomb') is entirely up to your world-building. [Answer] # Sound Waves! Years ago, I was working on some laptop theft prevention software, which in addition to a hardware alarm would activate a laptop's speaker. I had an odd situation on a particular Asus Aspire One laptop where the software would work great while testing, but every time a demo was done, it would BSOD. Naturally, this didn't make my client very happy. I worked on the problem for months trying to figure out what was going on. The problem never occurred on my laptop, only his demo laptop. I ended up buying extra laptops to test. At one point we went to go buy a second of that type of laptop. While looking up the model number, I found an article stating a particular fatal flaw. The speaker was mounted directly on top of the hard drive. At a particular frequency range, the hard drive would basically wreck the data coming out of it, which caused Windows to crash because swapfile was in-use because this laptop also had very little RAM. That particular frequency range happened to be almost exactly what I had chosen for my alarm sound effect. When I would test, the volume was way way down. But, during demos, we would crank it up and almost guarantee a blue screen. This problem made me start to wonder about other places this could be a problem. Around the same time, some guy posted a video of himself screaming at a hard drive array, causing read latency to increase: <https://www.youtube.com/watch?v=tDacjrSCeq4> Since then, I've thought that a particularly crafty malicious hacker could build a device with a bunch of ultrasonic transducers, and hidden somehow in a rack in a cage in a datacenter. With ultrasonic, while you can't hear it, you can create an interference pattern by using two lower frequencies that is in the range of what you need, while retaining the property of having an extremely directional beam. Your device could effectively shoot sonic lasers at particular devices in the datacenter, causing glitches-to-complete-failures in magnetic hard drives, all while not being heard by humans unless they were in the direct path at the time. Most of the drives for bulk storage are magnetic, with read/write heads barely floating above the drive platters spinning crazy fast underneath. Everything has to be perfectly in balance. SSDs don't have this trouble, so this method won't apply to them. [Answer] As others discuss, EMP will damage the machines that access the data, but not the data. You mention that your forces are owners or insiders, who can alter the design to suit, but need to conceal it from line staff who work there. I cannot see a non-detectable way to wipe the software without damaging your hardware. If you use internal malware, and even one backup survives, you are exposed. But to an evil genius, hardware is cheap. Let insurance buy you new hardware and that opens you up to many options. For instnace ## Plain old fire Burn the place to the ground. Simple as that. Build the place out of materials that'll squeak by the fire codes, but then store things in there that will subtly add to and sustain the conflagration. By "subtle" I mean that what fuels office building fires is the office trim and file cabinets full of paper. The trim can be made endothermic, the paper cannot. What's ironic about 9/11 is the jet fuel flashed off quickly, the paper sustained the fire. Likewise, start the fire with liquid or gaseous fuel and let the paper finish the job. Of course you'd need to either damage the sprinkler system or subvert it to your purposes. Also strive to use more burnable materials where excusable, such as you will want servers with plastic cases, and SSD rather than HDD. Lastly you'll want what steel mills and refineries actually do need: fire-truck-proof gates. Those industries don't want the F.D. yokels charging in and throwing a water hose on a hot metal bottle or sodium fire. In your case you are worried about terror attacks, or some other thing. And make sure to have onsite security doors which get F.D. Approval, but then frustrate their entry. Just build your building to make it hard to fight fires in, so they switch to 'let it burn out' and containment. Locating in an unfinished nuclear reactor would be a fun way to do it. [Answer] It isn't only a question of how big, but a question of where. EMP on the data bus is a different beast from EMP in the power supply, which is a different beast from a simple EMP generator within the room but not connected to anything. ## Case 1: EMP in the data buses The most difficult to create, but also the most devastating. You are supplying a high voltage in the cables through which the data passes. Assuming no intermediate devices burn out, your EMP will make it all the way to the storage drives and work their damage there. No guarantees that nothing can be recovered by forensic examination of the disks, but the disks themselves will be unusable. Getting a high voltage pulse into those cables is near impossible, unless you have physical access to them, as the cables are shielded against EMP for precisely this reason. If you do have physical access, introducing malware or something similar is a better way to do things. If you're a three-letter agency, for instance, you'll find it more rewarding to spy on people's data, rather than deleting it. ## Case 2: EMP in the power supply By far easier than case 1 and far more likely to happen, given exposed transmission lines. Except that any data centre will have decoupling and power conditioning systems before the power supply gets anywhere near the data, to ensure no unwanted spikes or dips get through. Unless you're actually inside the data centre,or better yet, inside the actual server room, in case they have a final redundant decoupling system, you're not likely to do much damage. Assuming everything goes your way, and you do successfully set off an EMP after bypassing all the protections, you'll destroy the servers, but probably not most of the data. They will need forensics to recover it, but it can be recovered. The electronics will be slagged, however, so the servers will probably be unusable. ## Case 3: EMP inside the server room Comparatively, the easiest way to cause some damage, but overall likelihood of causing less damage than a successful attempt at Case 1 or 2. Your EMP will weaken with the square of distance, so a million volts or so will be needed to get the whole room, given that the server enclosures will act as Faraday cages and protect their insides. With less voltage, you'll destroy everything nearby, with damage tapering off as you go further from ground zero. This depends on the geometry of the room and the kind of earthing in place. A rectangular room will take less damage than a square room; an L-shape will take less damage, unless the EMP goes off in the crook of the L. [Answer] Use paper stickers with housekeeping information to keep track of your disk drives! How would it help? Well, the stickers can have flat coils inside, just like those stickers that make detectors at shop exits beep at you. The coils can do the EMP and degaussing stuff, while also doubling as an antenna for a small control chip. That tiny low-power chip, and the coil, can be powered from a relatively small capacitor, which can be hidden under the sticker too. (Or inside the case, in case of SSDs, as those rarely have big enough cavities on the outside to hide the capacitor in.) The capacitor is absolutely essential in the case that the disk is completely disconnected for maintenance or other reasons when the kill-switch is triggered. It is recharged when the disk is online. Sticking that coil right to the disk's circuit board should allow for small enough capacitor to kill whatever chips are on the other side with EMP, or to degauss the platters. For SSDs that extra capacitor can also be connected directly to the board instead, frying all the flash chips as soon as the signal comes. Maybe that small controller could also be connected directly to the motor and the heads of an HDD, making it literally scratch out all the data by slowly spinning the platters under unparked heads. Add a powerful enough wireless transmitter to cover the whole complex, and a big red button (or a small gray one) for the trigger, and you are set! Keep in mind, though, that if someone tears off a sticker and notices a capacitor that's not connected to anything, they might suspect something and take a closer look at the sticker... With that caveat in mind, I think the idea is quite plausible. Someone might have to figure out exactly how big the capacitor has to actually be, but at least for frying flash in SSDs you most definitely can buy powerful enough yet really small caps. My original idea follows: --- > > Software could, and would in the context of the story, be found and purged. > > > What about embedded software? Modern computers are very damn smart. Every sizable component has a CPU, be it a network adapter or a microSD card. Intel AMT allows you to connect to a server remotely and work on it like it's in front of you: a display, a keyboard, you can even "plug in" your hard disk into it over the network. And the best part is, all this works as soon as you press the power button (some of it even before that), and it is completely out-of-band. That last bit means that any software working on this server will never see any AMT traffic, and it will think that you've actually opened up the case and attached that HDD. Despite having all that functionality, AMT works almost entirely on the motherboard itself, doesn't touch the main CPU or RAM, and is almost invisible to the "main" system. It's code is very obscure, extremely platform-specific and proprietary. Only some very smart hackers managed to get into it (and find a few glaring security holes...), under the normal circumstances no one will ever touch it in any way other than through the official client software from Intel. Every HDD and SSD has an embedded controller, too. Wiping an SSD "from the inside" is as simple as "forgetting" where the index for all of its flash memory is, maybe wiping that relatively small index beforehand for good measure. And on HDD you can just slow down the platters enough for the heads to land on them and dig trenches all over the surface. (The heads are too weak to magnetically damage the data quickly enough, so physically damaging the surface is the only way.) All the network hardware also has embedded processors, even the "really" embedded ones in case of bigger devices that are like normal computers themselves on the inside. --- What I'm getting at is, most people don't even realize that their microSD card may well be more computationally powerful than a PC from late 90s! No one ever really looks inside those embedded chips. Oftentimes you cannot even read the firmware from them, only flash the updates. (And thus their security is severely lacking oftentimes, except the "Security through Obscurity" kind.) If some kind of backdoor is installed on that level, I doubt that anyone will ever notice it. At least not until it's exploited and forensics start digging into the chips. No "normal" software will be able to detect that something's wrong, you'd have to take the device apart and dig in with a JTAG debugger to even have a chance. Let's say that one of the routers in the datacenter receives a malformed packet. It looks like it's a normal packet that got (unnaturally severely) corrupted in transit. Normally, it would be silently dropped, and higher level protocol, like TCP, will request retransmission. Suddenly, the router broadcasts that same packet over all its connections, and then immediately "dies", maybe requiring a firmware recovery procedure to continue functioning. Every server that receives the packet suddenly crashes due to CPU voltage dropping below acceptable minimum, and its disks experience catastrophic firmware failure that destroys all the data in a matter of seconds. A few more seconds later, the "smart" power supply infrastructure, which also received the packet of death, cuts the power to the whole complex. And perimeter routers just receive and drop the packet as they should, not a single bit of suspicious data gets outside. In just 10 seconds or so, the datacenter inexplicably goes from perfectly fine and healthy to totally blacked out and dead. All the networking infrastructure is lacking any firmware to even work. All the data is lost, either in unintelligible fragments randomly scattered across several flash chips in each SSD, or literally scattered all over the insides of HDDs. No one has any clue as to what has happened. Even if someone figures out later that the firmware of almost everything in the complex had peculiar bugs that just so happened to act together in such devastating manner, it can still look like it all was an accident. Since there are no traces of the packet that caused the whole mess, the only way someone might figure out that it was malicious is by contacting HDD vendors and finding out that the firmware slightly differs from what should have been there, but even that would be practically impossible to say for sure, due to how much things change internally during product life cycle. And in that last bit lies the catch. That 'small team' of yours will have to reverse engineer the firmware of every HDD, SSD, motherboard, network card and router in the datacenter, plus the smart power supply system. There likely will only be just a few kinds of each component, since they are ordered in bulk, and the slight variations in hardware revisions should not be much of a problem, but that's still a huge load of work, and it will take time. Plus, if any machine just so happens to be offline, as in "completely disconnected", its data will survive. The same goes for any disks that happen to be taken out at the moment. The only "safe" solution to that would be to have a small autonomously powered wireless bug on every HDD that will, when triggered remotely, turn on the disk, if it was offline, and order it to go kill itself. Or make it discharge a capacitor into a small flat coil glued to the disk. (Like those stickers that make detectors at shop exits beep at you. It can even have some housekeeping information printed on it, so that there is a reason for it to be there. No one needs to know that there is a coil inside the sticker. The capacitor will still be noticeable, though, unless you hide it under that sticker.) Or, you know, you could just kill it with fire. But that is outside of my area of expertise. [Answer] From a firmware engineer who works with electronics: > > What sized capacitors would it need? How long would it take to charge said capacitors? > > What are we looking at for coils? I've read 10-12 coils of copper tubing would create a rather massive field. > > > That is mostly science fiction. You are kind of asking "how long is a rope" or "how long does it take to fill up a bucket" :) EMP weapons could as I understand it be designed in all manner of ways, targetting special frequencies, or aiming to deliver lots of energy first followed by additional pulses. They will no doubt be designed as specialized for a particular purpose. Generally speaking though, an EMP weapon will fry a lot of semiconductors, particularly those without any form of protection. This most likely means the power supply of each computer, and then some. It's not selective at all. Diodes and integrated circuits are most likely to fry, less so the data disks. With some luck, the amount of metallic encapsulation surrounding the electronics might lead the burst away. Also please keep in mind that a server hall will have protection against lightning, and an EMP is basically a mini-lightning. So depending on where the EMP hits, it might do more or less damage. If the hall is built like a [Faraday cage](https://en.wikipedia.org/wiki/Faraday_cage), completely covered with metal isolated from the contents, an EMP won't do a thing. To purge the actual data reliably, you probably need to destroy the memories physically. No matter if classic hard drives or modern flash drives. Running some manner of virus or "soft erase" may or may not be effective depending on memory type. Notably, flash memories only have limited amount of write cycles, so running a program that erases and writes to the memory over and over will damage it physically. However, this is not reliable either, as cells will give up one by one, and you may still be able to recover the greater picture. And so the realistic way to erase the memories are to destroy them physically. --- Hide data in plain sight A fun alternative suitable for fiction, that's perfectly possible and not too technically advanced. Suppose the drives were custom-made, as was their firmware. So that each flash drive has two banks of every memory, but only one is known and documented. By sending a secret command to the the flash drives themselves, their firmware swap from reading memory bank 1, to reading memory bank 2. This goes instantly, like flipping a switch. Meaning that the original data is still there, hidden in plain sight. But the disks are now showing memory set 2, containing nothing but harmless information. And will carry on doing whatever they are supposed to do. Not only do you save the hardware, you save the data too. ]
[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/119232/edit). Closed 5 years ago. [Improve this question](/posts/119232/edit) How does one make a race that worships a personification of Death less evil? This race believes that dead souls go back to the River of Life to be reincarnated into a new form, so their beliefs aren't particularly radical or extreme. However, I am afraid that their death-worship may still rub people the wrong way. [Answer] *It depends on how they worship, not what* How do they Worshipp death? Do they go all “Kool-aid rapture”, or is it simply honoring those who have passed. As long as they don’t sacrifice humans (or at least, innocent people) they will not seem evil at all. [Answer] Have them celebrate death rather than being all macabre about it - think Mexican Day of the Dead style. Then assure that they aren't trying to shuffle people loose the mortal coil a little early. [Answer] Death is a necessary part of life. Depending on exactly what you mean by "race", this could be about a subgroup of humanity or it could be about a completely alien species. Either way, it's difficult to live if there is not death; if nothing else, an unconstrained population will sooner or later overshoot the ability of its biosphere to support it, causing famine, illness and death. An immortal species even more so, if they procreate at all. Some kind of death is necessary to keep their own population in check, and some kind of death is likely necessary (one could make a philosophical argument that harvesting plants is not the same thing as killing, hence likely) for the continued survival of the race. Recognizing this, your race views death not as something evil, but as something ultimately necessary and possibly even honorable. It then becomes a sacred duty of sorts for individuals to eventually die, and those who remain alive remember the sacrifices made by others that allow the continued survival of everyone else. This isn't at odds with killing others of one's own kind being thought of as wrong; knowingly taking the life of another need not be the same thing as accepting one's own, or another's, eventual death. If your race is one of carnivores, they may even distinguish between killing for food, killing in self-defense, killing in defense of others, mercy killing (say, a member of the group being mortally wounded during a hunt being put out of their misery) and killing for other reasons, which itself could give rise to interesting moral conflicts. Whichever way you go, something like this is going to show through in various aspects of society, not least of which in rituals centered around death and the deceased. [Answer] Death is not evil. Death is a process. It is the act of violence or murder that is considered evil. Consider these points: Natural death is considered an inevitable end. Their time is done and they must return to the maker by his side or in your case to start a new. Anyone who lives longer then they are suppose to (e.x. immortal) is considered unnatural. Make up a legend or a story that would explain that. Murder is a taboo. Taking someone's life is considered bad even if they worship death. No human sacrifices, or if you have to try to make it do not use knives or spill blood. It would be nice, if the tribe believe so, to point out that killing they are against. Set rules of what they considered good and bad. Embed them in their actions or tales, so it feels more natural when you present it to the person. Consider an idol or a statue of Death. Make it a woman with flesh rather than a skeleton with a scythe if you can. After all that image of the reaper was created to scare people. Also calling it "The River of Life" instead "of death" has already made them not sound so evil. [Answer] A lot of good answers so far, but just wanted to add. Its the opinion of others that count as to how a religion is viewed, if you are a member of that religion then it would seem normal to you, however a "non-believer" is the one you need to convince that its a normal religion. It's also often what that race does in general that defines that viewpoint on the religion itself, specifically historically in the real life Christianity is seen as a happy and peaceful religion, but i'm sure in the days of the Crusades this was not entirely the case, but after a few centuries and with the vast majority of Europe being part of that same religion, the opinion became what we know today of it being good (yes this is an oversimplification) Islam is, at its core, a religion dedicated to peace, unfortunately a very small minority have used it to spread terror, and thus is widely looked upon as bad. Going further back the Mayans and Aztecs aren't really looked upon badly for their religion, yes not vast amounts survived like they did for Egyptian/Christian/Jewish/Islam but people see what the Mayans did with astronomy and both did with construction etc, and look somewhat fondly on them, despite human sacrifice being common during religious services. So long as your culture that belongs to this religion is peaceful then often outside people will think of it as peaceful no matter what it is they believe. and to be fair, you've already explained it in a way that makes it sound peaceful or at least not very macabre. [Answer] They hold death so valuable that they go great lengths in preventing anybody from getting undeserved death. And they're good at it since they know so much about death. [Answer] If you have a ride-along character, have them receive an explanation from one of the faithful. As weird as it may sound, try avoiding the word death. Place more emphasis on the aspect of being “reborn” or “ascending.” Also, consider how the deity looks and behaves. Have depictions of them appear in bright colors. Describe them as physically beautiful and not monstrous. Have they moment they come to claim the faithful described as a warm embrace. Finally, show their culture and social structure in a positive light. Show that they revere death by natural causes, not by inflicting it. I hope these ideas help. [Answer] Make your Death character sympathetic, and make the worship focus on that sympathy. They can have texts where they appreciate the difficulty of the job she has, and acknowledging the love she shows when she eases people of their suffering and guides them to the next life. Maybe a story where there's a family weeping over a sick child, and when Death comes to take the child she weeps as well, and cradles the child gently into the River of Life; later those tears turn to tears of joy when she recognises the same child, born to a new life where he grows to a happy adulthood. [Answer] Comforting the bereaved: they believe that death is natural, inevitable and desirable, but still acknowledge that it is sad and frightening at a personal level. They take great care to ease the pain of people near death, and have rituals allowing family and friends to say goodbye. Death must not be trivialised: they believe that Death's duties are important, but that Death as an entity is not all-powerful. If many people were to die at the same time, that may overwhelm Death and lead to the River of Life being polluted by poorly-treated souls. Therefore they avoid war except as a last resort, never execute prisoners of war, and practice the best medicine available. Sustainability: the River of Life continues forever, so they must ensure that the world is always ready to receive the reincarnated souls. They do their best to protect the environment, do not waste resources, and keep a detailed record of history in the hope that souls may find the world familiar from their previous life. ]
[Question] [ [I have asked previously how I could create an earth-like world with as many deserts as possible in it.](https://worldbuilding.stackexchange.com/questions/41646/resources-for-climate-world-building) With these tips, I've designed a continent with a lot of deserts in it. Trouble is, this continent is very big, so it is bound to come across temperate and coastal zones, where a desertic climate is not possible. However, I would like this continent to be as barren as possible. If I can't rely on lack of precipitation to achieve this, what others factors could I use to create wastelands? For the purpose of this question, let's imagine that we this planet is earth-like and that the lands in question are located on a latitude between 45 and 60º in the southern hemisphere. Edit: Just to clarify, I want these wastelands to be naturally created, not man-made. [Answer] Several different ideas occur to me: [Badlands](https://en.wikipedia.org/wiki/Badlands), are areas where rain is actually the enemy of fertility and life. When you have deep underlying sediment that is poorly consolidated and at a reasonable altitude above the local [Base Level](https://en.wikipedia.org/wiki/Base_level) deep and rapid erosion precludes soil formation and retention. Wind, wind driven sand can easily account for those areas of the coastline near desert edges that would otherwise be fertile where they are down wind of the major sand and dust deposits. Winds can also rob an area of fine material as in the formation of [Desert Pavement](https://en.wikipedia.org/wiki/Desert_pavement), preventing soil development. Volcanic activity can create several different kinds of wasteland: 1. fresh deposits, freshly cooled lava is extremely barren and depending on it's chemistry and the local climate weathering can be extremely slow. Equally fresh [ash](https://en.wikipedia.org/wiki/Volcanic_ash) falls are also extremely inhospitable and can continue to be for extended periods even in geological terms. 2. rocky deposits like those left by [ʻAʻā](https://en.wikipedia.org/wiki/Lava#.CA.BBA.CA.BB.C4.81) lava flows are even slower to accumulate sufficient erosive and organic material for soil formation due to the deep "boulder field" terrain they leave on the surface. 3. nutrient poor magma, if the chemistry of the erupted material is deficient in certain elements then any soil that does form can't support flora and fauna, in New Zealand [Cobalt Poor Soils](https://en.wikipedia.org/wiki/Cobalt#Biological_role) on old [Ignimbrites](https://en.wikipedia.org/wiki/Ignimbrite) from [Rhyolite](https://en.wikipedia.org/wiki/Rhyolite) eruptions causes "bush sickness" in stock. 4. chemically difficult material, [Ultramafic Lavas](https://en.wikipedia.org/wiki/Lava), some [Andesite](https://en.wikipedia.org/wiki/Andesite) eruptions, and some forms of Carbonatites are so rich in certainly elements, like Magnesium or Florine, that they're antagonistic to life trying to colonise their deposits. This is an effect that can spread over huge areas in the case of Florine in ash from explosive eruptions. 5. [Sulfur](https://en.wikipedia.org/wiki/Sulfur), forms a number of toxic and/or corrosive compounds that often leach from volcanic deposits and can kill plants and animals directly or indirectly because it liberates toxic but normally stable compounds from the soil around them. 6. [Carbon Dioxide](https://en.wikipedia.org/wiki/Carbon_dioxide), a build up of CO2 in the soil as it percolates up from volcanic deposits underground suffocates plant roots and can even displace oxygen close to the ground killing wildlife directly. 7. heat, just having geothermal fluid, whether in the form of magma or super-heated water, close to the surface can kill plant roots and restrict the growth of plants that have shallow enough root systems to survive anyway. Salt, deposits of salt, whether waterborne or geological in origin, are lethal to a good number of plants and limit animal life in the area accordingly. This can be an ongoing problem down stream of such deposits as the rainwater that falls on such areas is too saline to support life. Such deposits are not limited to Sodium Chloride table salt either, they can include any water soluble metal salts that are toxic in high doses. Plant life, if your aim is to make an area impassible by reason of lack of forage then it can be relatively lush; if the plants are toxic, [Oleander](https://en.wikipedia.org/wiki/Nerium), [Caster](https://en.wikipedia.org/wiki/Ricinus), and many [Nightshades](https://en.wikipedia.org/wiki/Solanaceae) are toxic in part or as a whole. In areas where rainfall is scarce but reasonably reliable specially adapted plants are the norm so you could use large bands of "poison forest" to make areas impractical to navigate. For that matter forests dominated by coniferous species aren't friendly to beasts of burden or to humans trying to live off the land. [Karst](https://en.wikipedia.org/wiki/Karst), landscapes can be extremely dangerous to travelers who are unfamiliar with the area and tend toward surface aridity even when local rainfall is extremely high. [Wetlands](https://en.wikipedia.org/wiki/Wetland), if direct drainage routes are blocked, in part or wholesale, then water accumulates drowning most plants out and creating unstable bogs, trackless marshy glasslands, swamps with open water amid maze like forest or fens where the flow of water pulls you off-track over even short distances. That's everything I can think of off the top of my head. [Answer] I grew up in Utah and for years was impressed by Strawberry Reservoir. Check this out: [![enter image description here](https://i.stack.imgur.com/xORO4.jpg)](https://i.stack.imgur.com/xORO4.jpg) Not a tree in sight. Almost nothing larger than sage brush. Habitable only because there's fish in the reservoir. I think of it as a wasteland... and I've seen worse. I've seen reservoirs where, despite all the water, barely anything grows. So, let's talk about localized wastelands. Sandy or Volcanic Soil One way to make a wasteland is to make the soil sandy or volcanic. Water isn't retained in the soil. Sandy soil would usually result in an aquifer, meaning deep rooted stuff will grow (aka, desert plants). Volcanic is even worse. No Bacteria Soil needs bacteria — a lot of bacteria — to sustain plant growth. If an apocalypse killed everything down to the bacteria, there would be no plant growth. And it would take a very long time to recover (it takes organics to create the bacteria needed to create organics... a nasty little truth). Coal Seams The [Centralia Coal Fire](https://en.wikipedia.org/wiki/Centralia_mine_fire) has been burning since 1962. The area around the coal seam is a wasteland due to the higher soil heat. Coal seams can burn for centuries and while all those I know about were man-made (you know, "stupid human" problems), technically a lightening strike can get them going so long as a portion of the seam is open to the sky. Rocky, really rocky [Flood Basalt](https://en.wikipedia.org/wiki/Flood_basalt) is what you get when volcanism leaves sheets of rock over massive areas. The ultra-rocky soil is usually anything but lush. Dead Lake Areas An inland lake with no outlet like Utah's Great Salt Lake or the Middle East's Dead Sea is a scrappy area due to the high salt content, especially if it's at a higher altitude like the Great Salt Lake. Consider also the Bonneville Salt Flats, the high-salt desert left behind when Lake Bonneville drained away. High Altitudes Finally, everything above the treeline is scrappy. A mountainous (think "Tibet" mountainous) region would have very limited vegitation only in lower canyon areas. [Answer] Let's take a step back. Specifically, what is your motivation? Are you a fan of the visuals of vast dune seas? Looking to create a resource shortage for characters to fight over? Exploring the idea that bleak landscapes create pensive, wise people? If it's simple resource shortage you want, have this be a young continent. You get plenty of craggy mountains, a lack of available salt (as it's never been submerged beneath the ocean). This will hamper at least animal life. Lots of barely cooled basalt lava flows couldn't hurt. Throw in a destabilizing new animal species or two. Say, goats recently got to the continent, and are overgrazing, causing desertification. Hmm ... how exotic do you want to get? Could it be that your world is a CO2 atmosphere, and this continent has just seen the evolution of photosynthesis? Some new critter is poisoning its neighbors with toxic oxygen! Or ... the nuclear option. Perhaps this continent is recovering from an asteroid strike of near dinosaur-killer levels. Lack of light (let's say some effect localized this to the southern hemisphere) has killed off all the plants, hence the animals all died. Here's one for you... let's say that local trees have evolved a special structural chemical which local bacteria cannot digest (this has happened on Earth). Life on your continent is slowly choking itself out under the weight of never-decomposing tree trunks. [Answer] Take a look at the south of Argentine Patagonia, i. e. the southeastern end of continental South America, which lies roughly between the 40° and 50° S parallels (excluding the island of Tierra del Fuego). The Andes create a rain shadow that means that the prevailing westerly winds discharge most of their humidity on the Chilean side; on the Argentine side the places located right by the feet of the mountains get a lot of rain, but as you progress east the climate becomes extremely dry. This is the [Patagonian Desert](https://en.wikipedia.org/wiki/Patagonian_Desert) (in parts it is technically a [steppe](https://en.wikipedia.org/wiki/Steppe), I believe). It's the 8th largest in the world. North of Patagonia you have another desertic region, [Cuyo](https://en.wikipedia.org/wiki/Cuyo_(Argentina)), which is only livable because of extensive irrigation, and the arid parts of the Pampas. The fertile pampa regions for which Argentina is famous get their humidity mostly from two sources: an anticyclone in the south Atlantic which brings moist oceanic air from the south, and northerly winds from Brazil. The latter can only penetrate deep into the region because there are no significant mountain ranges between southern Brazil and northern Argentina; if there were, the arid climate would surely extend north for thousand of kilometers. The Atlantic anticyclones sometimes bring [disastrous storms](https://en.wikipedia.org/wiki/Sudestada) to the mouth of the Río de la Plata, and up the littoral region as far as 300 km north of Buenos Aires, but these are not persistent features. Based on this real-life example I would say your best bet is to make your continent very large, place high mountains in the way of the prevailing oceanic winds, and try to work out how to disrupt other sources of humidity. This might be impossible unless you want to go the Mordor way and box it all into a (totally unrealistic) rectangular mountain range. [Answer] [Shield rock](https://en.wikipedia.org/wiki/Shield_(geology)) or [cratons](https://en.wikipedia.org/wiki/Craton), such as found in northern Canada (as far south as 50°N), exposed by [glacial erosion](https://en.wikipedia.org/wiki/Erosion#Glaciers) of topsoils are arguably wastelands. At warmer climates you may find treeless expanses of lichens, mosses and scrub, while colder climates will remain rocky for eons. This area may be pitted with thousands of small lakes, which freeze over in the winter. [Answer] It just went to my mind very simple idea. How about that the planet contains small amount of H2O itself? The amount of water takes about 66% area of Earth, so how about 33% on your planet? Earth-like planet I understand as: similar size and gravity, similar atmospheric pressure and magnetosphere, similar chemical composition (but slightly different proportion) etc... It would recalculate as much less humidity in atmosphere and most of the land would remain desert (except coastlines, reservoirs and rivers). The question that remains is if life can really evolve on such planet but we couldn't answer based on our knowledge yet. [Answer] Solar Radiation may be best suited to your needs. If Solar Radiation were increased it could kill plants over vast areas, starting spreading from the equator. This would also be very inhospitable to humans without protective suits. Volcanic Activity is of course another option, if your planet is very geologically unstable then it could have large areas be prone to lava flows, covered in volcanic rock, or poisoned with acid. Post apocalyptic radiation Did they drop the bomb? If so it was probably targeted at more heavily populated regions built in fertile areas. These may no longer be inhabitable. Low Water Content Planet Obviously your planet doesn't have to share Earth's exact composition, if it has less water then it would have larger desert regions. Frozen Deserts Antartica is the worlds largest desert, but it doesn't seem to be exactly what you had in mind. [Answer] Even Australia is remarkably dry for its medium size and positioning (lots of coastline.) The reason we think in terms of proportions of coastal, temperate, etc - is because we experience that on many continents. But, these proportions rely on things like the jet stream. The tilt of the planet. Moon (tides) and maybe even the magnetosphere. Make a planet with no tilt, no moon, no jet stream and the proportions of temperate, desert, etc will change. California's recent mega drought (four years of very little rain) killed of major swaths of trees and may have boiled down to a high pressure ridge that directed ocean air too far northward. I think these sorts of things make a desert continent entirely feasible. [Answer] Building on User54373's suggestion of a young continent... 1. Life has not yet emerged onto land. The whole of your continental interiors will therefore be "deserts" because there are no plants, no proper soil, and so on. Think Earth in the [Ordovician](https://en.wikipedia.org/wiki/Ordovician) or [Silurian](https://en.wikipedia.org/wiki/Silurian) Period. There is plenty life in the sea, rivers and lakes. Riverbanks and shorelines have life. Everywhere else is barren rock or (in rainy areas) maybe rock with a layer of algae on it. 2. Have a supercontinent. All the continents are amalgamated into one massive mega-continent. Think the [continent of Pangea in the Permian period](http://www.ucmp.berkeley.edu/permian/permian.php). Even in temperate latitudes, there will be large areas which don't receive any rainfall. The wind picks up moisture as it travels over the sea, then that falls as rain on the land. However, all the rain has fallen out of the sky long before the wind can reach the interior of a supercontinent. 3. Have a supercontinent in an ice age. As above, but a lot of the world's water is locked up in glaciers and ice caps. This makes sea level drop, so your supercontinent is even bigger! And there is less water to fall as rain (10 to 20% less than today on Earth), so forests turn into grasslands, grasslands turn into deserts, and the existing deserts (hot and cold) expand their area massively. [Answer] Get Your Own Brand New Planet The easiest way to make a barren but mid climated planet is: Just don't give time to life to develop. Life take lots of time to develop/evolve/colonize so maybe your planet is in a early stage. A nice stage to take is it already got plenty of ocean life (and oxygen made by blue algae) but land is not colonized yet despiste some fish do some walking to nest eggs in the mud maybe. Edit Another way to achieve it is by turning the planet of surface utra poor in minerals and with little to none volcaninsm. That way only a few places where there are impacts with rich mineral meteors can sustain crops. ]
[Question] [ I was wondering what kind of planet would lead to aliens being significantly larger and stronger than humans. From my understanding, a planet with lighter gravity would lead to larger creatures, but they would most likely be weaker, as it takes less effort to move stuff. But a planet with heavier gravity would lead to an alien which is shorter, but most likely significantly stronger, as it takes more effort to move itself and things around it. Is my understanding faulty, or is there a way for a planet to produce these kinds of creatures? What are some things they would need in order to get around this size? They should be bipedal with two arms and legs, but no other restrictions besides those. [Answer] You can do it on a planet identical to earth for all intents and purposes. They are aliens not humans, just something with a vaguely human body plan, you have an entirely different evolutionary history to work with and their are plenty of organisms much bigger than humans, even intelligent ones. Just come up with a different starting point, heck just look at gigantopithecus. If the hominid line had started from something like that, or even just something gorilla sized, instead of something close to the body size of a chimp, humans might fit your description. And that is just an example you can make up an evolutionary history that has nothing to do with primates or terran-like life. [![enter image description here](https://i.stack.imgur.com/3zzyg.jpg)](https://i.stack.imgur.com/3zzyg.jpg) [Answer] UPDATE - after re-reading the question, this answer is an acceptable answer to a totally different question, which was "Can I have aliens significantly larger and stronger than a human, but still in human shape?". I don't know where I pulled those two qualifiers from. # aliens not unreasonably larger than humans (new answer)... Yes, it is possible. To be as close as possible to the human shape, just check the [largest primates](https://en.wikipedia.org/wiki/List_of_largest_mammals#Primates_.28Primates.29) on Wikipedia. With some adaptations from the "human shape" section below - a stronger heart, thicker blood vessel walls, valves and possibly even a secondary heart in the abdomen, you can easily get a 3 m tall human weighing around 250 kg. The bone structure only needs minor tweaking to be able to bear up to twice the weight, so while you will need thicker bones, especially in the pelvis, this added thickness might not be too visible if we stay under 300 kg (the rhino bones can bear a load [up to one hundred tons](http://www.bbc.com/news/science-environment-26242256) but that comes at a cost) and slightly different pelvic and especially knee and foot joints. Feet will need to be larger no matter what, but not too disproportionately so. It would be good if we could accommodate a less mobile and fragile foot. From an evolutionary point of view these aliens would probably never have climbed trees, so a great neck mobility isn't necessary. The skull will probably be larger than expected and provide more protection from falls (a larger, more complex meningeal layer with more powerful shock absorbers, and "plated" interlocking skull bones). The eyes will need to balance the advantages of being deeply inset with the advantages from being outside with a wider field of view; in the end they might be retractable, like Cu Chulainn's [riastradh](http://www.shee-eire.com/Magic&Mythology/Warriors&Heroes/Warriors/Males/Cuchulainn/Page1.htm) in Irish mythology. The minor surface-to-area ratio will mean that the aliens will need to get rid of more heat for square inch, which calls for less hairy bodies than Earth's large primates (there is still debate on why exactly humans lost most body hair, though). Abandoning a full-human blueprint, an anthropoid bear - all the way to [Megatherium](https://it.wikipedia.org/wiki/Megatherium) - is possible. The gait will not be human-like, and the creature will require a tail to help balance. It is totally possible for a Megatherium-analogue to get rid of its claws and have more civilized tread and table manners; they'll still have a low metabolism, though, because otherwise the fuel requirements for their mass would be prohibitive. On the other hand, this might be a powerful incentive to developing intelligence and manipulatory skills to improve foraging chances. # ...with giant human shape (old answer) I'm afraid there aren't many ways. > > They would be like humans in almost every other way, for convenience. > > > Consider a frame twice as large in every direction than a human being. It would have a volume eight times larger (2x2x2), and therefore weigh reasonably at least five or six times as much, possibly the full eight times as much if its density remains the same as a human's. But the maximum weight that an animal frame can carry is related to the section of its bones, and to move it the same applies to muscles; so you would need a section six (maybe eight!) times larger. This translates to a size factor of SQRT(6) or 2.45, not just 2. This creature would need to be appreciably disproportionate in his feet, legs and lower body. This is why the largest known primate, the extinct Giganthopitecus Blacki, is thought to have been a preferential quadruped rather than a biped: from [Wikipedia](https://en.wikipedia.org/wiki/Gigantopithecus), > > The majority view is that the weight of such a large, heavy animal > would put enormous stress on the creature's legs, ankles, and feet if > it walked bipedally; while if it walked on all four limbs, like > gorillas, its weight would be better distributed over each limb. > > > Similar considerations apply to the heart and circulatory system, with the added difficulty that pressure is proportional to height and gravitational acceleration; a larger being and a heavier world require a slightly different material with which to build veins and arteries, or they will burst. This already happens in some terrestrial mammals - the [giraffe](https://www.ncbi.nlm.nih.gov/pubmed/16724937) has [specialized muscles and valves](http://news.bbc.co.uk/earth/hi/earth_news/newsid_8368000/8368915.stm) to keep its arteries intact when it lowers its head, and even so it has 280/180 blood pressure. Then you have metabolism and pulmonary volume. You can fiddle a bit with the air's density and oxygen contents - with [enough oxygen](https://news.nationalgeographic.com/news/2011/08/110808-ancient-insects-bugs-giants-oxygen-animals-science/) you can get [bugs as large as a dinner plate](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2880098/) - but as any SCUBA diver will tell you, this requires further fiddling with biochemistry. In the end, the larger a human being gets, the less human it can afford to look. [Answer] > > Gravity & Bio-mechanics > > > The principal contributing factors to physical size of fauna is: gravity and bio-mechanics. According to [Jonathan Payne](https://pangea.stanford.edu/researchgroups/paleobiology/), a paleobiologist at Stanford University who has done extensive research on how body size has evolved over the history of life. If you took an animal and blew it up in size, mathematics of bio-mechanics dictates that the creature’s mass would increase cubically, or by a power of three. However, by the same ratio of size increase, the width of the creature’s body, and thus its bones and muscles, would increase only by a power of two. As the alien creature gets bigger it needs to dedicate more and more of its body mass to its bones to support itself. > > Atmospheric Oxygen > > > On Earth, a big factor that has historically (over the length of life on Earth) driven animal size is the percentage of oxygen in the air. More oxygen lead to bigger fauna, less oxygen lead to smaller fauna. It isn't entirely clear if this is mostly due to animal respiration or mostly due to availability of food. > > Metabolism > > > The Earth’s biggest terrestrial animals, elephants, for instance, can reach about 13 feet tall and weigh up to 7.5 tons. In the past, however, life got far larger: Dinosaurs like the [Titanosaur](https://en.wikipedia.org/wiki/Titanosaur) weighed in at nearly 80 tons—10 times larger than the African elephants of today. The reason has to do with the fact that dinosaurs were reptiles. To maintain their higher body temperatures, warm-blooded mammals spend about 10 times more energy than ~~cold-blooded~~ reptiles do on their metabolisms. This is energy that a mammal can’t devote to increasing its body size. Consequently, terrestrial mammals aren't very large in size. > > Foraging > > > Following from the previous point, aquatic fauna, the Blue Whale, is a mammal and larger than any terrestrial fauna ever. Of course buoyancy and gravity trade-off explain this disparity. An important distinction though is the foraging habit of Blue Whales. Blue whales swim across ranges of thousands of miles to find krill to eat. Even the African elephants can cover up to 80 miles in a day looking for vegetation. The large fauna require food to supply their metabolism, growth and reproduction requirements. An alien would need to move large distances to acquire all the food it needed unless the alien planet had surplus vegetation that somehow regrew quickly such that the gigantic alien did not need to cover thousands of miles on land to forage. > > Evolutionary pressure > > > The largest animals through history on Earth are understandably herbivorous. Its a question of energy efficiency or economy of metabolism; how much metabolism is invested in acquisition of food? For comparison, consider carnivorous animals like lions and tigers on a hunt. They are physically strong animals but spend a lot of energy on hunting their prey. This energy could alternatively have been spent on growing bigger and reproduction, instead evolutionary forces drive these animals to work in groups (reproduction priority) rather than have larger individuals. On the other hand, herbivorous animals don't fight with their food, so physical strength beyond that required to support their own weight is not an evolutionary priority. > > Speculative Gigantic Alien > > > Lets get our ingredient for gigantic alien Gravity: Low Oxygen: High Metabolism: cold-blooded Foraging: Cornucopia of rapidly regenerating food source Evolutionary pressure: Preference for physical size A likely candidate alien would be a hybrid of flora and fauna. Unlike herbivorous animals that spend energy on eating plants that acquire and store energy from photosynthesis, the candidate alien has its own energy producing capability. This saves it time and energy on foraging. [![enter image description here](https://i.stack.imgur.com/ZLDMY.jpg)](https://i.stack.imgur.com/ZLDMY.jpg) The alien plant could have perennial incident solar energy, say there are multiple stars in the planetary system. Then this alien could be acquiring energy through some manner of photosynthetic process in a continuous manner. This savings in metabolic energy could be spend on growth and building strength, which leads to gigantic and strong alien. > > Answer: I AM GROOT > > > A flora-fauna hybrid alien. [![Groot](https://i.stack.imgur.com/FmdEJ.jpg)](https://i.stack.imgur.com/FmdEJ.jpg) -- Thanks to a comment, I did a bit more research on warm and cold blooded animals. I've mentioned some interesting points of distinction that would shed light on the kind of alien planet and alien creature. If we have full creative control then a synergy between planetary conditions and alien could be achieved. Warm-blooded vs Cold-blooded metabolism and survival pros and cons: There are many advantages to being warm-blooded. Warm-blooded animals can remain active in cold environments in which cold-blooded animals can hardly move. Warm-blooded animals can live in almost any surface environment on Earth, like in arctic regions or on high mountains where most cold-blooded animals would have difficulty surviving. Warm-blooded animals can remain active, seek food, and defend themselves in a wide range of outdoor temperatures. Cold-blooded animals can only do this when they are warm enough. A cold-blooded animal's level of activity depends upon the temperature of its surroundings. A reptile, for example, will increase its body temperature before hunting and is better able to escape predators when it is warm. Cold-blooded animals also need to be warm and active to find a mate and reproduce. Being cold-blooded, however, has its advantages. Cold-blooded animals require much less energy to survive than warm-blooded animals do. Mammals and birds require much more food and energy than do cold-blooded animals of the same weight. This is because in warm-blooded animals, the heat loss from their bodies is proportional to the surface area of their bodies, while the heat created by their bodies is proportional to their mass. The ratio of a body's surface area to its mass is less the larger the animal is. This means that larger warm-blooded animals can generate more heat than they loose and more easily keep their body temperatures stable. Smaller warm-blooded animals loose heat more quickly. So, it is easier to stay warm by being larger. Warm-blooded animals cannot be too small or else they will loose heat faster than they can produce it. Being large requires a greater food supply, but for mammals, being small also requires a lot of food to generate more heat. Small mammals need to eat very often to survive because they need more energy to keep a constant body temperature. They also need to eat high energy foods such as fruit, seed, and insects and even other small mammals. Larger mammals can get by with eating lower energy foods or eating less often. In an environment where food is scarce, such as in deserts, reptiles have an advantage. Since cold-blooded animals do not have to burn a lot of food to maintain a constant body temperature, they are more energy efficient and can survive longer periods without food. Many cold-blooded animals will try to keep their body temperatures as low as possible when food is scarce. Another disadvantage to being warm-blooded is that warm-blooded bodies provide an nice warm environment for viruses, bacteria and parasites to live in. Mammals and birds tend to have more problems with these infections than do reptiles, whose constantly changing body temperatures make life more difficult for these invaders. However, an advantage of this is that mammals and birds have developed a stronger immune system than cold-blooded animals. A reptile's immune system is more efficient when the animals is warmer, however, since bacteria probably grow more slowly in lower temperatures, reptiles sometimes lower their body temperatures when they have an infection. Finally, I haven't considered the possibility of gigantic size for [extremophiles](https://en.wikipedia.org/wiki/Extremophile), which are creatures that live in extreme conditions, like hyperthermophiles. If the alien planet was something like Venus, and these aliens could absorb the energy in the high temperature, high chemical environment, they could solve their metabolism needs and possibly grow very large. [Answer] Make the planet colder. One of the most important facts governing body size is the "square-cube" law - that the volume to surface area ratio of an object changes as an object changes in size. LSerni touched on this regarding body strength and weight, but the other critical place this law matters is in heat generation and dissipation. Heat generation scales with body volume, but heat dissipation scales with surface area. As a consequence, large animals have problems with being too warm, while small animals have problems with being too cold. That's why you find many large animals in Arctic environments but few in deserts, and why the last Ice Age featured many species that were larger than their cousins who are alive today. A planet that is colder than Earth would therefore encourage the development of larger hominids. [Answer] The light build of humans has more to do with terrain than with gravity or climate: it optimises endurance and minimises energy consumption, good when the species is evolving in a savannah. In such an environment, you can only afford to be heavy by being exceptionally strong (elephants, lions), but in that case you don't need to be particularly smart, so that's not too plausible for an intelligent species. Intelligence did give human ancestors an edge in hunting technique and avoiding enemies, but physical strength wasn't so crucial. To evolve intelligent ape-like creatures without losing strength, put them in an environment where they need it despite the intelligence, and can afford the extra energy. I'd say your best bet is denser vegetation, such as apes generally inhabit. Somewhat weaker gravity will certainly be helpful, so that bipedal locomotion is easy despite the high stature and mass. A cold climate, like [Arcanist Lupus suggests](https://worldbuilding.stackexchange.com/a/96292/9852), is also a good idea because it encourages both sturdy build and intelligence. Fat and fire, IOW. So: make your planet humid, cold and with strong seasons, so that much of the land mass is occupied by dense boreal forests. [Answer] I picture your hominid giganticus resembling the Hulk somewhat (except perhaps not with the green skin). The creature would have to have thicker and heavier bones to support their greater weight, and the might be more dense overall. Gravity is not the absolute indicator for height. Consider the various different feline species out there - large felines like lions and tigers are very similar in appearance and build to smaller ones like lynxes. They have evolved to fit fit certain niches, and probably also to the size of their prey. Your planet could simply have larger versions of predators, herbivores, plants, etc. [Answer] Although what you have described appears to make sense, we really do not know what effects a planet's greater or lesser gravity have on its indigenous life. Currently, life has only evolved on one planet that we know of, so our available sample size for studying such effects is... one ...which is not a valid sample size for this kind of conjecture. It could just as easily be theorized that omnivorous (prey) primate size is determined by the appetites of the carnivores which hunt them. Tribes of apes, which are individually big enough to fill a tiger's stomach, loose only one member each time the tiger successfully hunts. Tribes of smaller apes loose multiple members during that same time frame. The bigger apes therefore have a survival advantage (at the tribal level) over the smaller apes. Even bigger apes however have no additional survival advantage because one tribe member dies for each tiger meal, even if half of the corpse is left uneaten. So if you want a bigger evolutionary starting point for your intelligent primates, give your tigers bigger stomachs. [Answer] The planet wouldn't necessarily have to be larger than Earth to have stronger gravity. Maybe it consists of denser matter than Earth has... a planet with a core of solid gold might make for an interesting situation. The greater the gravity, the more dense the atmosphere that the residents have evolved into. So your super strong big planet dwellers might find Earth's atmosphere too thin to support their needs. Why would they have to be bipedal? Life on another planet may evolve in a different direction, due to slightly different circumstances, or just the element of random chance. It would make for a less convenient, but seemingly more authentic story, if life encountered on other planets didn't look like life as we know it. On Planet Minotaur, they could have four legs and two arms, for speed and dexterity. Planet Millipede... oh, we've lost count already. And there's Planet Pogo, where they have only one leg, and the Earth visitor has to leave before they laugh themselves silly from seeing an entire population hopping around. The possibilities of non bipedal intelligent life are limited only by the imagination. 'ugly bags of mostly water' [Answer] Your planet doesn't necessarily need to be very different from earth... It needs to have a different history. We once had big animals, but earth's history and evolution negatively selected them. Big animals are usually slower, easier targets, and a huge body mass has a lot of constrains. Big animals require big territories and open enought for them to coup with they life needs... Take for example the larger animals we still have... They are not in the very dense and closed forests, but in wide open savannas... Or in the sea. Even in forests, we once had bigger animals than we have now (not bigger then savanna's, though). They were hunted down to extiction many ears ago [Answer] A planet identical to earth could produce aliens 50% larger than humans (mass not height). That's a bilaterally symmetrical biped of 93kg (human average is 62kg). If you want noticeably larger you could go 2.4m tall but you'd probably need to double the mass to 125kg or heavier. Homo sapiens is a recent evolutionary result. This planet has had at least 5 Mass Extinction Events and all life on earth has evolved from the survivors of each of those. The Cretaceous-Tertiary mass extinction saw the end of the dinosaurs. They had many top predators that were significantly bigger than humans. There's an infographic [How do humans size up to the dinosaurs in Jurasic Park](https://www.businessinsider.com.au/dinosaur-size-comparison-chart-2015-6) Aquatic predators like sharks, orca, dolphins and extinct species can also be bigger than homo sapiens. Megalodon? I'm using predators as the prelude for intelligence because "How much intelligence does it take to sneak up on a blade of grass?". But that ignores the role of cooperative community and omega-3 fatty acids in human evolution (if any). This also ignores the potential for elephants or hippos to evolve enough intelligence to become the apex species in the absence of homo sapiens. But for a few environmental die rolls maybe the pachyderms could have out-competed us. ]
[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/84271/edit). Closed 6 years ago. [Improve this question](/posts/84271/edit) An interesting aspect of world-building I haven't felt very exposed to is what the native race(s) of a planet would call their own world. On Earth, we call it Earth, after the stuff beneath our feet. Imagining a planet whose dominant species "grew up" there like ours has on Earth, what are some ways in which they might refer to their home? The best ones I can think of are "terra firma" names like Earth -- whatever the word for earth, ground, soil, rock, grass, water, etc. is in the alien language -- or variations on "home." Would one of these be common among species in different galaxies? Or can you think of a pattern that might be more common? [Answer] A good way to look at this answer is see how we have referred to our planet. Here are just some suggestions. You are correct that we call it Earth, and it seems that most other languages currently call it something similar. In many languages, the planet is referred to as Soil, or Ball of Earth, but that indicates that this is a fairly new thing to call our planet, seeing as the previous consensus was that our world was not at all a sphere. For example, The Chinese call the earth Di Qiu, which translates into "Ground Sphere", but used to refer to the world as Tian Xia, which translates to "Under the Sky". Now, let's look at the Romans. We don't know what the Romans called Earth, but we do know that the other planets in the solar system were named after Roman gods. They are called such because the Romans are pioneers in astronomy and they ended up getting to name those planets. Romans also had a goddess, Terra, who is the goddess of the earth. Many polytheistic religions have an Earth Mother and a Sky Father, and should they have discovered the existence of planets, may also name the Earth after their own Earth Mother deity. Another way to look at it is how countries are named. Countries like Afghanistan Belgium are named after their people: land of the Afghans, land of the Belgae. If your alien race is connected enough to identify themselves as a single group, it is entirely possible to see the planet be named after the species, like Humania. Similarly, it could be named after a feature of the planet, like how Japan is refered to as "The land of the Rising Sun". Similarly, if the world is taken by an alien civilization, it might be named by them. Countries like Canada comes to mind, where a name was derived from broken communication between two people I know it's a little all over the place, but I hope this will give you some insight. [Answer] I can think of others, it depend on their orientation to their environment, but I imagine the local word for Earth, land, (perhaps sea or water for ocean oriented beings) would be the most common. Others could be "God's Realm", the "Kingdom", "Our Gift", "Our Home", references to an ownership abstraction. Imagine that for most purposes we own our houses, farms and animals; but we also recognize our Kings own the entire kingdom, including us and our property. Add one more level of abstraction, and God owns it all, and the Kings; i.e. a King of Kings. So the planet is God's property, or house, or farm, or something similar. Yet others can be focused on position: Humans were once convinced that Earth was the center of the universe, and could easily have begun referring to Earth as The Focus, The Center, The Primary. Even The Reason, as in the reason the universe exists because everything revolves around it, and therefore serves it. Finally, your planet may be given a proper name or named after a human role, based on a mythology of stories that anthropomorphize it, how it came to be, and its family. Like Gaia. So your planet could plausibly be called The Littlest Sister or the Great Mother; or just "Edwina:" Here is my Earth based creation story. The gods were Sol, husband of Venus, the most beautiful of stars. They had children that were amorphous spirits, the youngest and littlest sister they named Edwina. Edwina was rebellious, and she so wanted to be a mother like Venus that she became pregnant, and had a child out of wedlock with Mars, that she named Seth. This angered Sol so much he killed Mars, the bloody body is still out there as a warning. But Sol still loved Edwina so much he could not bring himself to destroy her, and Venus begged Sol for Edwina's life. So instead Sol turned Edwina and Seth into planets with life, and now Edwina is the great mother of us all, she still cradles her infant Seth [the Moon], and she is watched over and warmed by the love of her father and mother to this day. [Answer] It starkly depends if you're talking about the name of a planet, or if you're talking about words are used for the home of a species or basically anyone. Further I am going to assume the latter as the answer to the former is as simple as: Someone made the name up based on what they first thought about. --- So, what names will a group of people (even aliens have peoples) choose for their home world? The only generalisation that can be made is that most often a word meaning home or something radiating safety, protection or comfort seems to build the root of the eventual term/concept. E.g. let's look closer at a semi-randomly chosen language, like Icelandic: The Icelandic equivalent to the English 'world' is 'Heimurinn'. It stems from the word [heimur](https://en.wiktionary.org/wiki/heimur) which in turn seems to have roots in either heimr and heimaz. Looking at other languages like German for similar sounding words, we find the words Heim and Heimat which both refer to the same concept as the English home. Looking at the German word for world though, we find Welt which doesn't sound anything like the previous heimurinn we found only a few hundred kilometers away from German. Welt in turn stems from the Old German word [weralt](https://en.wiktionary.org/wiki/weralt#Old_High_German) which is a compound of the words for wer (En.: man) and alt(En.: time, age, old) - so to say: Home of Man(kind), which gets back to the concept of safety, protection and comfort. [Answer] In many languages, the name for Earth is basically "land", more in the literal sense of dry land (instead of a political division, like "country"). Even now in English, Earth is both a term for soil, and the name of the planet we live on. Same in Spanish: tierra, Earth, land, and soil. Long before people knew the Earth was a sphere, many people basically thought that the entire universe was basically divided into three parts: land, sky, and ocean. (Stars and space, what we think of today as most of the universe, were though to be much smaller than they actually are, and were part of the sky, which was a dome). It was only later they put it together that the "sky" was actually much bigger, and in fact an optical illusion-- it actually isn't a blue dome, even though it appears to be. Also, the water and land aren't co-equal parts; the water, though expansive, is a relatively shallow cover over some parts of a large rocky planet. Even though we learned all of this, we still kept the same basic name that we had long before this understanding. We live on the land, the soil-- the Earth. So look at another language, Finnish, a non-Indo European language. Earth, the globe, is maapallo, which is made up of two words: maa, earth, land, soil, and pallo, ball or globe. So the Finnish word for the planet Earth can be translated as "land-globe" or "soil-ball". I would say that aliens probably name their planet on whatever material they live on. A dolphin like species would probably call their homeworld "water" or "ocean". Beings that evolved on a gas giant would probably call their home the gas-liquid that they live on. [Answer] One possible analogy for this is the names that Native American tribes invented to refer to themselves as a people. From an objective standpoint, these have a few advantages over the Earth/Terra forms that you refer to in your question. The Indo-European language family has shared roots, hence the cognates "Earth" (English/German) and "Terra" (Spanish/Italian/French). It's difficult, if not impossible, to trace the origin of these terms to their original semantic meaning. Native American languages, on the other hand, are much more varied (they do not have [shared roots](http://www.encyclopedia.com/literature-and-arts/language-linguistics-and-literary-terms/language-and-linguistics/native)) and arise from somewhat independent cultures, giving us a much larger sample size as well as greater confidence in their semantic originality. It would be neat to compare Native American names for the world, but all I have on hand is [a few of their names for themselves](http://blog.nativepartnership.org/american-indian-tribes-names/) -- not from a very reliable source, but I've heard the same thing from a few different places so it's at least a believable urban legend. Most of them are simple: variations on their word for "[the] people". A few of them add adjectives ("white clay people" and "people of the desert"). For a brand-new civilization on a random planet, there probably isn't sufficiently advanced technology or philosophy for them to contextualize themselves in terms of other planets or people. So the simplest solution here is that they call themselves "the people" and they call their planet "the place." As time goes on and they start to think of other stars/planets as places and not just sky-decorations, the old terms will become idiomatic and new terms or variants will be invented to handle the discoveries. EDIT: [Here](http://www.nativehistorymagazine.com/2013/01/tribal-names-and-their-meanings.html?m=1) is a more complete and more trustworthy list of Native American tribe names in their native language. It's a much more interesting list -- using this as a base, it would make a lot of sense for civilizations to name their planet e.g. "place of the sand" or "place of the white rivers." ]
[Question] [ It is widely known that the US Naval base at Pearl Harbor, Hawaii, was attacked in the morning of Sunday, 7th December, 1941 - resulting in the US entering the Second World War (source: [History.com](http://www.history.com/topics/world-war-ii/pearl-harbor)). My question is, how would have the Second World War played out if the Japanese fleet were wiped out, or at the very least seriously crippled, in a freak event en route (e.g. rogue waves, typhoon, meteor strike etc), preventing the raid on Pearl Harbor and wiping out the effectiveness of a significant proportion of the Japanese Imperial fleet? Note: this question is not about how the Japanese fleet was stopped in this scenario, but about the outcomes were it stopped. Would the United States still have joined the war? What would the consequences be for the war in Europe? [Answer] The true effect of the crippling or destruction of the Japanese fleet prior to the attack on Pearl Harbour might have been to swing the balance of power in Japan back to the Imperial Army. In the 1930's, various factions struggled for supremacy inside Imperial Japan. The "Army" faction saw China and Siberia as the best sources for raw materials that Japan needed to continue existing as an industrial nation, while the "Navy" faction saw the British, French, Dutch and American empires and possessions as the proper place to gain these raw materials. The Army argument was that their preferred plan involved less risk (a divided and warring China and a more or less exhausted Soviet Union post civil war), and the materials were fairly close in geographical terms, allowing the Empire to easily control these resources. The counter argument was that they were relatively undeveloped and would require huge investments and a lot of time to develop. The Navy argument was that the Empires in the East had already developed the resources and had pools of trained manpower to extract these resources. There would be no "costs" to develop the resource base, and it was also thought most of the people there would actively cooperate if their white Imperial overlords were displaced. (no one seems to have thought these people would object to having their white overlords replaced by Japanese overlords...) The Army lost the argument in 1937 when the Russians defeated the Japanese army in the Battles of Khalkhyn Gol, essentially closing off the Siberian resources argument. The Imperial Navy needed time to prepare for its multi faceted strategy, but their hand was essentially forced with the American embargo of oil and steel. If the Imperial fleet had not been able to deliver its blow against the Americans, and this was known early enough to call off the remaining attacks on the European Imperial possessions in Asia, then the Army probably would have been able to muster the support for a renewal of their fight against the Russians and expanded operations in China; changing the completion of the war entirely (the German invasion of Russia would not have been opposed by an extra 25 divisions rushed from Siberia in the winter of 1941, for example). Beyond that, the calculus become very involved, so alt histories written from that point could have innumerable outcomes. [Answer] The attack on Pearl Harbor started on November 26, 1941, with [the departure of the Striking Force from Japan](https://en.wikipedia.org/wiki/Attack_on_Pearl_Harbor#Approach_and_attack). It was just one of [many operations planned for December 7, 1941](https://en.wikipedia.org/wiki/Pacific_War#Japanese_offensives.2C_1941.E2.80.9342), but it was the keystone: the entire Japanese battle plan depended on knocking the American Pacific Fleet out of action. This gives two major possibilities for alternate courses of history: ### First option The fleet is wiped out early, and this fact is communicated back to the Japanese high command. The rest of the operations are canceled. This doesn't mean Japan stays out of the war, though: the Allied [iron, steel, and oil embargos](https://en.wikipedia.org/wiki/ABCD_line) were crippling to Japanese industry. It's likely that a new Pearl Harbor-style attack would take place within six months. However, this delay could turn out to be a fatal error for Japan. The [Essex-class](https://en.wikipedia.org/wiki/Essex-class_aircraft_carrier) and [Independence-class](https://en.wikipedia.org/wiki/Independence-class_aircraft_carrier) carriers were already under construction by December 1941. With six of Japan's aircraft carriers sunk, Japan has only six fleet carriers facing five American fleet carriers, and the American carriers are 50% larger than the Japanese carriers. This won't deter the Japanese -- their naval doctrine is based around [decisive combat between battleships](https://en.wikipedia.org/wiki/Kantai_Kessen) -- but combat realities are different, and the extra carrier force available early in the war could result in a much shorter Pacific campaign. ### Second option The fleet is wiped out late, on the eve of the attack, or so abruptly it can't communicate back to Japan. With so many plans in motion, they have no option but to continue. The Pacific War starts on schedule, but with no surprise attack on Pearl Harbor, the Japanese declaration of war arrives before the attacks, and there is no [Day of Infamy](https://en.wikipedia.org/wiki/Infamy_Speech). The early stages of this war would go much as they did in the original timeline. The American plan will probably adhere more closely to [War Plan Orange](https://en.wikipedia.org/wiki/War_Plan_Orange), and there may be some battleship-vs-battleship fights that otherwise wouldn't have happened, but the key elements for American victory ([submarine](https://en.wikipedia.org/wiki/Gato-class_submarine) and carrier construction in particular) were set in motion long before the start of the war. The likely difference will come at the end of the war. With less motivation to demand an unconditional surrender, it's possible that the Allies would be willing to accept a negotiated surrender that involves Japan returning to its pre-[Sino-Japanese War](https://en.wikipedia.org/wiki/Second_Sino-Japanese_War) borders, rather than unconditional surrender and occupation, which could shorten the war considerably. Whether Japan would be willing to accept is anybody's guess. [Answer] The question you ask is related to various conspiracy theories. Did the US government want to get involved in WWII? One could make a good case that the US government was already involved in the war. [Lend-lease](http://en.wikipedia.org/wiki/Lend-Lease), [Neutrality Patrol](http://en.wikipedia.org/wiki/Neutrality_Patrol), they clearly took sides in the war in Europe even without a formal declaration of war. The Pearl Harbour attack galvanized the public opinion to get even more involved and to get the country onto a war footing. The conspiracy theorists claim that the government deliberately didn't warn Pearl Harbour to get their new [Maine Incident](http://en.wikipedia.org/wiki/USS_Maine_%28ACR-1%29#Sinking). I don't believe this, but maybe without the Pearl Harbour strike the isolationist sentiment would have prevailed. What else happened around that date? Japan had many [coordinated operations](http://en.wikipedia.org/wiki/Pacific_War#Japanese_offensives.2C_1941.E2.80.9342) in the Pacific theater. If not for Pearl Harbour, might the attack on the Phillipines the next day have had the same result regarding public opinion? [Day of Infamy](http://en.wikipedia.org/wiki/Infamy_Speech) Without the strike at Pearl, the fitst Japanese attack would have come closely after the declaration of war. This might have taken some of the rancor out of the war -- or not, considering what happened at Bataan. Perhaps it would have been [Europe even more first](http://en.wikipedia.org/wiki/Europe_first)? Extra battleships Would the surviving battleships have affected the Pacific war? Nobody knows. The US might have tried to use them, only to have them sunk by carrier planes. Or they could have been used as anti-air/anti-surface escorts for carrier groups. Axis declaration of war Again, nobody knows if that would have happened. The German declaration of war resulted in some [submarine warfare](http://en.wikipedia.org/wiki/Second_Happy_Time) on the East Coast, but Japan didn't reciprocate by going after Russia. Summarized, there might have been a small likelihood of a peace settlement in the Pacific, which gave the Philippines and the rest to Japan while the US concentrated on Europe. And a small likelihood of no Axis declaration of war, which could have led to Pacific first. More likely, nothing much changes. [Answer] Since nobody has, I'll cover the European consequences. Japan launched many simultaneous attacks that day, but the only other one against the US was in [the Philippines](https://en.wikipedia.org/wiki/Philippines_Campaign_%281941%E2%80%9342%29) and this happened seven hours after Pearl Harbor. There was time to call it off. If the attack went off as planned the US would be dragged into war with Japan. But if it didn't, if the attack on the Philippines was cancelled, the US entry into war with Japan would be delayed. Either way, *the US entry into the European War would have been delayed* at a critical point in the war in Europe. On Dec 11th, 1941 Hitler went against the advice of his staff (something he would do again and again) and [declared war on the United States](https://en.wikipedia.org/wiki/German_declaration_of_war_against_the_United_States_%281941%29). It's one of Hitler's greatest blunders and one of the war's greatest mysteries why he decided to do it. *Without a smashing Japanse victory at Pearl Harbor this would not have happened. War between Germany and the US was by no means inevitable. The US was still neutral, and it was still building up its military. An attack by Japan gave the US even less incentive to start a two-front war. As for Germany, they were mired in a battle with the Soviet Union and the [Battle of the Atlantic](https://en.wikipedia.org/wiki/Battle_of_the_Atlantic). Military logic said opening an new front was madness. Without the spectacular victory of Pearl Harbor to excite Hitler's imagination, it's likely cooler heads would have prevailed. Instead, the Germans would have waited for the outcome of the inevitable massive naval battle in the Philippines planned for by both the Japanese ([Kantai Kessen](https://en.wikipedia.org/wiki/Kantai_Kessen)) and the US ([War Plan Orange](https://en.wikipedia.org/wiki/War_Plan_Orange)). They would have negotiated with Japan to guarantee Japan declares war on the Soviets. Without the US as a belligerent in Europe, supplies from the US to the Allies would be reduced. The US would need to keep the veneer of neutrality and continue the awkward lend-lease arrangement which restricted the volume, speed, and types of material they could send to the Allies. As a neutral the US could not conduct any combat operations against the European Axis. Lacking a ["Germany First"](https://en.wikipedia.org/wiki/Europe_first) agreement with the Allies it's probable the US would have held back more of their material to fight the Japanese rather than lease them to the British and Soviets. The impact of the [Tizard Mission](https://en.wikipedia.org/wiki/Tizard_Mission) would be reduced. In Sept 1940, in order to circumvent US neutrality provisions, Britain simply handed the US many fantastic new technologies such as the [cavity magnetron](https://en.wikipedia.org/wiki/Cavity_magnetron) necessary to produce compact radar sets, the [variable-timed fuse](https://en.wikipedia.org/wiki/Proximity_fuse) for air burst artillery shells, a jet engine, rockets, superchargers, gyroscopic gunsights, submarine detection devices, self-sealing fuel tanks, and plastic explosives. They hoped the US would develop these, build them with their massive industrial capability, and then Britain could buy them back. In our alternative timeline there would be no US aircraft equipped with these wonder weapons to fight the Germans, particularly U-Boats. The US would have been more interested in putting them to good use against the Japanese rather than lease their best weapons to the British. In North Africa this means no US tanks to resupply the British Army. No great victory at [El Alamein](https://en.wikipedia.org/wiki/Second_Battle_of_El_Alamein) where US tanks made up half the British army's force (M3 Grants, M4 Shermans, and M3 Honeys). No [Operation Torch](https://en.wikipedia.org/wiki/Operation_Torch) to simultaneously open a second front in North Africa. Without the US in the war the British will be very hard pressed to hold on to Egypt and the Middle East. Over the skies of Germany this means no [US strategic bombing of Germany](https://en.wikipedia.org/wiki/Strategic_bombing_during_World_War_II#US_bombing_in_Europe). The US contributed about half the total damage to Germany, now Britain would have to go it alone. Furthermore, the "round the clock" bombing campaign would not have happened, Britain preferred to reduce losses by bombing at night, allowing the Germans to freely rebuild and move material around during the day. German industry would take less of a beating, and less of its military would be required in the [defense of the Reich](https://en.wikipedia.org/wiki/Defence_of_the_Reich) allowing them to throw more at the Soviets at a critical moment of the Eastern Campaign. In the [Battle Of The Atlantic](https://en.wikipedia.org/wiki/Battle_of_the_Atlantic), the US is spared the slaughter of the [Second Happy Time](https://en.wikipedia.org/wiki/Second_Happy_Time), but the British have to go it alone. Without US aircraft and destroyers bolstering the escorts, the Germans would have continued to successfully exploit [the GIUK air gap](https://en.wikipedia.org/wiki/GIUK_gap). Without US industrial help, new British invented anti-submarine technologies would have been slower to come online and less would be available. Even with full US support the battle was nearly lost. Without it, it's likely [Britain would have been strangled in May 1943](https://en.wikipedia.org/wiki/Battle_of_the_Atlantic#Climax_of_the_campaign_.28March_1943_.E2.80.93_May_1943.2C_.22Black_May.22.29).* On the Eastern Front, US supplies to the Soviet Union will also be reduced. While US tanks and airplanes were generally considered inferior by the Soviets, they were still better than nothing and could be used by rear and training units to free up better equipment for front line units. What would be sorely missed is US logistical support in the form of trucks, trains, industrial machines, and raw material to rebuild the Soviet industrial base. [Here is an exhaustive list](http://whatreallyhappened.com/WRHARTICLES/pearl/www.geocities.com/Pentagon/6315/lend.html). *Without this support the Soviets would have less capacity to rebound again and again from crushing defeats in the field*. 1942 was already a bad year for the British and Soviets, without the German declaration of war against the US it would have been much worse. [Answer] If the Japanese had never bombed Pearl Harbor, there would be a much larger possibility that the US would have never entered the fighting. While we might've been forced to fight Japan, I do not believe the US would have sent men to the European Theater. If this had happened, the Axis powers not only would've defeated Britain, North Africa would've never been freed, Italy would have stayed a friend to Germany, more and more Jews would've been killed in concentration camps. There are other possibilities that I cannot answer but must bring up. Russia might've never been attacked by Germany, Germany might have gotten Hiesenburg to developed the nuclear bomb before the US did, and the Zimmerman Telegraph might've never been intercepted and the US could've been attacked by Mexico.And obviously, Hitler would still be alive and leading an empire to world domination. [Answer] The Japanese attacked America because they knew it was inevitable that America would join the war and they wanted to cripple a future enemy before they could strike back. If the attack never happened, America would still have joined the war so I doubt the outcome would be all that different. ]
[Question] [ Let us define enchanting as binding a magical effect to or channeling it through a physical form. Background: Magic is an "energy," or exotic matter/energy perhaps, that exists essentially as an invisible cloud that does not directly interact with normal matter of its own volition. It can be coaxed to interact, such as the standard fireball or "Force push," or as a source of energy. It is not directly limited by standard physical laws so a bit (or a lot) of extra energy popping up out of nowhere is fine. You may assume that, when used for enchanting, it can take on a property that allows it to bind and interact with the material if given additional energy, based on the material's physical properties (I.E. Photoelectric Effect). You may assume that sufficient energy to cause an effect is available, as if a special battery were plugged in when needed. There is to be a group with glowing weapons or other trinkets, enchanted to emit even brighter light on command with an energy input. These objects will be made of metal, and/or perhaps some form of crystal1. Consider this an example application. Other effects may be applying forces on impact, creating heat/fire around the object, or cooling the object noticeably. Use your imagination for additional effects, if you wish. Question: What sort of explanation could be given as to how these effects are stored/applied for metals2 often used in pre-powder weapons, or jewelry, due to the physical properties of those materials? --- 1: Consider crystals a bonus, if you know how to extend your answer to cover them. 2: Bronze, iron, steel, etc. Consider Earth c. 800-1100. [Answer] Magic, almost by definition, is something that isn't explained by science. You can literally have magic applied to your weapon however you want it to be. That being said, there's a few ways that have shown up in multiple fantasy settings: Runes Magic could be applied by carving runes into the enchanted item. Different rune words would have different magical effects and appearances. Forged with magic In many settings, magic blades are simply forged with some sort of magic used in the crafting process. This can lead to an item that doesn't necessarily look any different, or it can lead to one that glows/hums/burns with violet flames. Imbued with magic gems Lastly, including magic gems and jewels can be the source of magic for an enchanted weapon. Similarly, dark magics could be bound to a weapon using pieces of bone carved with runes. [Answer] This question is a little difficult to answer based on hard science, so I'm going to stick to focusing on the methods of bonding things together (in this case, magic and metal). --- The main (best?) way to do this is chemically. You say `it can take on a property that allows it to bind and interact with the material`, so perhaps that property is a chemical 'surface' that allows it to bind with the metal. This may be in the form of raw chemical compounds which would react on contact with compounds on the surface of the item; however, it is more likely to be in the form of some adhesive. There are plenty of strong adhesives designed to bond things together permanently; look, for example, at [Araldite](http://en.wikipedia.org/wiki/Araldite), among other epoxy resins. From the article: > > Araldite sets by the interaction of a resin with a hardener. Heat is not necessary although warming will reduce the curing time and improve the strength of the bond. > > > So, if the magic's 'surface' was the resin, and the metal coated with the relevant hardener, then when the two interact they will stick together. Perhaps, if you want to really increase the strength of the bond, you might add some chemicals which react exothermically to each surface as well, to provide the heat to strengthen the bond. However, many implementations of enchantments have a limited time duration, so perhaps leaving the heat out would give this part. --- As for the effects of the enchantments, this is impossible to define within the boundaries of science. However, since your magic does not operate on a closed system, it makes it a touch easier, so the basic principle goes like this: * Effect is chosen (either by some telepathy or by predefined enchantment type) * Energy is required `->` draw some in / create some * Use energy to create effect (fire, ice etc) [Answer] Considering your wording, "It can be coaxed to interact," I would consider a psychology solution rather than a chemistry solution. The goal does not need to be to permanently chemically bond the magic to the item, but simply to keep them together. Consider the human ideal version of "marriage." There are no physical bindings tying the two individuals together, and yet we traditionally treat it as binding them together tighter than any cord could ever manage. They want to stay together. I would rely on a ceremony that works along those lines, but slightly weaker: make the ceremony give the magic a home. The concept of home is also very powerful, binding a living thing to an inanimate object or space. Once one has a home, one can reach out more forcefully, knowing there is always a place to retreat to, allowing small magics to become great. A few traits I find worthwhile: * Magic could literally "grow into" a home, starting off in a very well constructed item and connecting to it as it grows. * In magical combat, magic could run away, diving into the object, leaving it as though it was unimbued. * Different materials would have different affinities for magics, just as different individuals like different styles of rooms in a house. * It would not be unreasonable for a tiny shard of magic to find refuge in a powerful weapon, and slowly grow into greatness. This would allow for swords that seem to acquire magic through combat, even though they never actually met an enchanter. * The wielder would qualify as a next-door neighbor. This offers tremendous options for magic to influence its wielder just through casual interaction. * Effects, like the heat and cold and glowing you mention, could be seen as side effects of the magic. If the magic is living inside the house, you will see the side-efects of it leaking out around the object. A glow might be seen as magical-waste that happens when a magic is not fully trimmed (the idea being a perfectly tuned magic would not waste anything like glowing when it is at work). Glow also might be seen as the magic boasting. [Answer] Maybe the magic isn't stored IN the weapon. Perhaps the weapon is simply changed to make it easier to naturally direct the ambient magic (mana) in a specific way. Then the user of the weapon/item can channel power into it to activate the effect. The power flows through the user the same way that a regular magic spell would, but since the weapon has been constructed and designed to channel the mana in a specific way the 'spell' can be cast easily, without the training a mage would have. Using a magically enchanted item is as easy as turning on a light switch, casing a spell without an enchanted item is like building a computer from scratch, one takes an expert, one anyone can do. This would allow someone using an enchanted item to decide when to power it. It would also put a limit on using an enchanted item, maybe it's easy to use a sword that glows, but using a sword that makes everyone around explode is still a strain on someone since they have to fuel some of the power. As to how to make magic work, If you used the crystal idea it's easy to suggest that crystals are constructed in such a way that they channel ambient mana through them. Much as how you could cut a crystal to reflect or refract light into specific patterns if you wanted to it's possible to cause crystals to reflect magic energy in specific pattern which causes an effect. Perhaps it's the ACT of swinging a sword which causes a magic effect to happen, as you swing you sword through the air it's also flowing through all the ambient magic energy, causing some to flow through crystals in the sword to cause the magical effect to happen. Of course you don't have to use crystals, the same effect could be done with any item, but crystals seem mystical and I think would likely feel more 'natural' as a catalysit for magic, larger items could have crystals built into them that hold the actual enchantments. Plus this could regulate how rare/powerful an enchanted item is. Perhaps certain spells need certain type of crystals because of how they channel magic. Maybe the higher quality the crystal the easier it is to forge into a spell, thus the more powerful the enchantment the more/better quality the crystal. You have a natural way to regulate power levels of items such that people don't ask why everything isn't enchanted. This could even set up a plot point of people fighting over crystal mines or sources of high quality crystals for the magical potential they offer. [Answer] > > Any sufficiently advanced technology is indistinguishable from magic > > > That said, lets dig deep into this. Method 1 : Bending Reality Magic is a way to bend reality itself, allowing imagination to take corporeal form, this is where the "coaxing to interact" part comes into play. If you can imagine it, it can "be", that is to say, magic allows the user to liberate himself from the bonds of physical laws. What would limit you from becoming god-like, would be the laws which govern magic itself. Now if we take this view, "enchantment" becomes quite simple. There are limited things we can do to items when we enchant them (limited by our imagination!), we can make things sharper, or lighter, or harder, or sentient (so that a weapon fights with its own will), we can make it ignite or freeze whatever it touches, we can also alter its dimensions, making it longer or shorter, thicker or thinner at will. The role of magic is to provide some sort of bridge between imagination and reality; once the "enchantment" is finished, reality simply adjusts itself to accommodate whatever change has been induced. The key here, is that this adjustment need not be known to the enchanter. Maybe there are molecular changes or the introduction of exotic matter or crystal rearrangement due to the creation of a novel alloy, but all of these details are lost on the enchanter, who sees it, quite simply, as magic. Now the limitation of this system could be some sort of conservation law. Perhaps there is an asymptotic limit to how far reality can be bent (is it dependent on position in space (magic hotspots)? or time(age of magic)? or something else? Who knows?) or perhaps instead, there is some sort of exchange whenever magic is done, perhaps the enchanter loses his imagination/mind. Or even better (and more realistic, if that word can even be used in such a discussion), perhaps it is the item which the limiter. Certainly, I would imagine enchanting a suit of steel mail to be harder, or an iron blade to be sharper, an easier task than enchanting a pair of shoes to compress space-time. The point is: there is real science going on behind the scenes (which reality takes care of) but the enchanter need not know about any of it. It's sort of a like a magic trick where even the magician is not in on it, and reality is the guy in the back pulling all the levers and working the smoke machines. Method 2: The Magical Method In this scenario, magic is simply another kind of ordinary physical phenomena (like the reflective properties of light, or the catalytic activity of certain peptide sequences arranged in a specific 3-dimensional structure (enzymes). In that case, magic is just a name for yet another observable phenomena (YAOP). As YAOP, magic can be subjected to the cold and iron scrutiny of the scientific method. Experiments can be done, theories devised and disproved, careers ruined, geniuses born, ignored, and than later hailed as geniuses, giants used as stepladders, in short, all the chaos and clarity that is science. Where enchantment comes in, would perhaps be "Applied Magic" (as opposed to theoretical magic), where this YAOP can be harnessed and manipulated to do useful things. The more pervasive it is in the universe, the more useful things we can do. If, for instance, magic is an intrinsic part of everything so that all physical phenomena are connected to it, then its manipulation suddenly becomes quite useful (to say the least). For example, if magic is some sort of fundamental particle then perhaps we can change the properties of an object by manipulating this fundamental particle. How? Well perhaps, the particle can interact with other phenomena (like light, or heat or leptons). In this case, we do need to know what the science is, because the science is the magic. Anyway, its late, I have a few more, but it will have to wait till tomorrow. [Answer] As Oldcat says "use magic to apply the enchantment." Specifically, use magic to modify atoms to be able to receive power (for always-on effects that derive power from the magic around them), to modify atoms into a brain (to make switches and mind-reading effects (ie: if you can will your swords on/off; or for sentient swords)), and into batteries (for charges/charged effects that don't replenish themselves, eg: ring of three-wishes (which also needs a brain to interpret wishes, or a bound demon or something)). Doesn't have to take any time either - if you want instant magic items :) [Answer] My starting point for thinking about magic in this way would be magnets ( how do they work??? ) in that magnetism is a quality that certain metals can be imbued with and when they are, they respond to energy in the form of a magnetic field. As a fringe benefit you also get the possibility that a metal that can carry magic might interact with a thaumaturgical field even if it is not itself magical. I might think of it like this: When an item is imbued with magic, perhaps by subjecting it to a sufficiently strong magical field, the atoms in the metal are aligned with a magical energy source in such a way that a magical "charge" can be used to manipulate them. The basic manipulations that you could apply at this kind of low level within a vaguely scientific framework would be fairly limited- changing their rate of vibration would allow them to be heated or cooled, it might be viable to create a potential difference between different parts of the metal, causing a shock effect if both parts came into contact with someone. If it allowed electromagnetic manipulation you might also be able to attract or push other metals or to induce current or heat in them even without making contact. A magic sword that caused enemies armour or weapons to heat up would confer some advantages. Given that our magic source behaves a lot like magnetism it would be reasonable to suggest that the magical field could perhaps be manipulated too. Alternatively, magical objects would be the only things that couldn't be manipulated through a magical object. As for the energy source, that is more tricky and likely to head into the lands of handwavium - which is fine, as long as it makes sense. I would have the source of energy as being something that comes from a person or, if you want to make things more interesting, perhaps from all living things. It can only be directed consciously and you might choose to have the facility to direct it either being a talent displayed by different people to different degrees or requiring a lot of training and focus to be able to draw the energy into an implement to make it useful. This gives it a non-deterministic quality which makes it harder to investigate scientifically and prevents it from simply being "yet another energy source." Where the field exists and someone trained in directing it exists and they have an implement through which they can direct magic, they can operate. It may be that the way the first magical items were created was very iterative- it started with simple objects picking up a magical field and then by bringing those together with the appropriate direction, a stronger field could be created to make stronger items possible. This creates the interesting idea that maybe the places where magic weapons are created are ancient, carefully constructed and maintained, because it takes a long time to build the strongest locations. If it then takes a long time for the charge to be picked up by objects, you have a reason for them to be rare and interesting. There is also an interesting potential role for mage-smiths, shaping the magic-bearing metals to maximise their effectiveness. [Answer] Okay, I'm assuming that since you have magic, you have people that can utilize magic. Perhaps there are mages, wizards, or whatever that are capable of casting spells such as making glowing lights, or fireballs, or whatever you like. You can have them enchant any particular item that has significance to them at the cost of putting a piece of themselves (perhaps their lifeforce, soul, or generic energy/power) into the item. This diminishes the abilities of the enchanter without the object, but enhances their abilities with the object, and allows others to use the object with the enchantment as well. (This is almost a straight rip-off of the One Ring from the Lord of the Rings at this point, but you can work on this to make it your own without too much trouble). Let's say you have a mage that puts a fireball spell into a sword. Now when someone wields the sword it is a flaming sword. But from this point on that mage can no longer cast a fireball spell. Also, your enchanted object may have properties related to how much of this power they can store. This would ultimately become a capacity for the power. Say a shield being large holds a higher capacity of stored magic than a small ring. I'd like to think that ceramic items which are porous would work better than say most metals. Crystals would also work well here where a larger crystal lattice would have more space to hold onto whatever powerful particles you are using. Metals can be forged to work this way too, but wouldn't have this property by default. Think basically like steel. Carbon is infused into the iron to add strength to the iron. Whatever particles impart power on your enchantments could similarly be infused to other metals. Finally, keep in mind it is not magic stored in the enchanted items, but rather some aspect of the mage being stored in the items which is what enables the item to utilize magic in much the same way that the mage would have been able to do. I would expect somewhat porous materials like various ceramics, to work best as they have the most room to hold the enchantment (though they are brittle and easiest to destroy with explosive consequences). I would expect crystals to be next best, and they'd be at least a bit less brittle then the ceramics, making them the material of choice for enchantment. I'd expect plant matter including wood to also work reasonably well, again for it's porous nature. Metals would be the least enchantable, and would require a rigorous forging ritual to be involved, but they would be the most stable and hardest to destroy or disenchant. Metal alloys would be almost impossible to enchant because there is simply no room for the enchantment to fit with the additional material. Steel in particular would be all but impossible to enchant with anything useful. [Answer] Let's start with a working definition of magic. Imagine a parallel dimension without material substance as we understand it. Forge a channel between our world and this dimension, embedding the channel's material opening into the blade of the soon to be enchanted short sword. The laws of physics in the immaterial dimension do not allow for matter to exist no matter what. The laws of physics in ours insist that matter exists whenever the underlying causal conditions for its existence are present. The point where the two dimensions interact is a no-man's land... Not a matter/anti-matter conflagration, not the mutual destruction of opposing particles under a single all-encompassing set of rules. Something deeper than that. The intersection point is where the rules themselves bend, a point where anything is possible. Now add carefully crafted crystals as a flow-control valve between the two opposing rule sets. The crystal wraps around the intersection on our side and its shadow, an immaterial equivalent of the crystal covers the intersection on the other side. How wide the channel opens is controlled by the proximity of the crystal to the intersection. Leave it at rest and only a trickle gets through; just enough to express itself in the spontaneous generation of the lowest massed pseudo-material, light. Thus the blade glows. Pull the crystal back away from the intersection by a millimeter or so, and more anti-material rules leak into our world, creating more light. Pull it back even further and a field of dis-corporializing energy pours forth, swallowing the blade, its wielder and everyone else within 20 feet. A big flash of light and a lot of screams. Then the crystal snaps back into place and falls, rolling to the bottom of the newly created crater. Glowing faintly with the intersection once again safely contained, it waits for the next would-be magic user to come along and find it. [Answer] Whilst physical elements do not impinge on the magical dimension, when 'magical force' mana or whatever, is brought into the physical world, it has the potential to bond with molecules. It doesn't take the form of additional particles or affect the normal physical fields in any way, but has a one-sided reaction to them, overlaying bonds, being 'squeezed' or caught between nuclear fields, the surrounding fields and their molecular nature determining the form the mana is 'caught in' or applied to a device or object. For this reason magical material may exist 'naturally' where mana has been drawn regularly or with particular intensity, but in general it is a matter of deliberate regular application of mana to a desired object to impart a given property. One might say for instance that pure copper has an extremely poor ability to retain a mana 'coat' and that mana is inclined to escape swiftly, typically producing photon emission as it depletes (which it does 'automatically' & continuously) bonding mana-imbued copper with mana-imbued tin can prolong the duration of the emission, or imbuing pre-formed bronze with mana will emit long duration heat emissions. Whilst the mana itself might not be directly affected by other materials, the interaction between those materials upon an already imbued device or material naturally changes the state of the mana, causing release, slowing release, intensifying it or altering it's expression in some other way. (polarizing imbued iron for instance, or applying any other active chemical effect to the material. perhaps bringing two imbued devices into contact might have some logical effect also (imbued copper into contact with imbued photoreactive substance) imbued wood into contact with imbued bronze.. whatevs. Most elements & alloys have some sort of association with an 'mythical' element, overlay real world chemical effects & reactions, bonds & processes for einstein approved magic. [Answer] Magic generally doesn't enchant items, otherwise it could easily be dissipated. There are two "known" ways to enchant items. If you have Aryan races in your RPG, they can sacrifice a few of their HP (permanently) to bind the materials in the item more powerfully. This is done, in essence, through quantum entanglement (the way the atomic nucleus is held together by the strong force). They must hold the item or have made the item to have sufficient depth of a connection to it. The other way is through the god/desses. Most magic would effectively be electro-weak forces of physics, consisting of free electrons. This isn't sufficient to bind deep enough for a permanent enchantment. But the (highest) gods, made the atomic forces and they can bind at the depth of those quantum entanglements. [Answer] ## Science-based + Magic tags = Clark-tech Instead of your world being a place of actual magic it is the home of a long forgotten advanced race that left their technology behind. You planet is actually covered in an invisible swarm of nanobots that the old ones created to serve their every need. If they wanted food, they would tell the swarm to make them a burger and they would buzz around synthesizing complex organic molecular structures into the shape and nutritional qualities of a burger. If they cut themselves, they would tell the swarm to mend the wound. If they got bored of being human, they would tell the swarm to turn them into a unicorn. If they wanted a nice place to sleep for the night, the swarm could build them a flying castle. Basically, it was the ultimate post-scarcity society powered completely by this ever present swarm. However... the swarm made the old ones so powerful their society was about as stable as a nation made of people owning their own private nuclear arsenals; so, they had no problem wiping themselves out. In this world, magic is the study of the language of the old ones. Knowledge of the old language is incomplete so there are very few people who know how to ask for more than a few things. ## How does metal and gemstones fit into this? The swarm is not as dense as it once was. While there are still enough nanobots around to hear your requests, they need sources of silica, iron, gold, copper, etc. if they want to make more of themselves for larger tasks. So, a "magic staff" is actually just the raw materials the swarm needs to reproduce. A large quartz crystal gives them silicon for making chip wafers. Diamonds contain carbon for making nanocarbon structures. Rings of gold & copper, are wiring components, so on and so forth. Nanobots can make themselves from a variety of materials, but the more pure and completely you meet their ideal needs, the more and better forms of themselves they can make thus extending their abilities to server the caster. Since most people do not know the language of the old ones, enchanters often engrave their weapons with phonetic inscription allowing anyone to read off a command without having to understand it. So a magic sword could be a steal blade inlaid with precious metals and gemstones to feed the swarm, and the inscriptions are meant for the wielder to read to give some predetermined ability to the weapon. So, if you read the sword, and it has the materials inlaid in it for the swarm ro make the right kind of new bots to do what you have asked, then a few moments latter, your blade may be covered in thin layer of nanobots waiting to burn their way through the next thing that offends the edge of your blade. ]
[Question] [ I remember reading about how a lot of the early paleolithic societies and proto-human species like Neanderthals and Homo Erectus used sign languages before spoken languages. It made me wonder how a society that never developed spoken language would be like. Let's say that 100,000 years ago, Homo Sapiens dies out but a new species by the name of Homo Mutus takes over. Homo Mutus is very similar to Homo Sapiens. The difference is that they require less food than Homo Sapiens but they also lack a voicebox. Homo Mutus cannot speak, scream, whisper, or make any non-chewing sounds with their mouth. Can Homo Mutus develop an advanced civilization like Homo Sapiens has without spoken language? Will it be harder or easier to do so with everybody having to use sign language and written languages instead of speaking to get points across? [Answer] # Sign language can be better Although there are plenty of situations where sign language would be worse, I think it can actually be better than spoken language. The idea is that language is required or at the very least boosting a group's ability to advance. This is because the knowledge can spread. As Newton is claimed to once write about his scientific progress: "if I have seen further, it is by standing on the shoulders of giants". The important factor here is that the type of language is less of a factor. We can see in our current society that speech is a definitely great way to spread knowledge and we have done so for millennia. Interestingly it was improved by the written word. But both are still derived from language. In that regard sign language has enough variation and expression to have similar knowledge transfer. Even in this society you can speak volumes by just lifting your middle finger. The drawbacks are that it is more difficult in groups for example. People need to face the person, as well as see all the different gestures that are made. However, such arguments are easily made from a speaking society. A sign language society could have many advantages compared to the spoken language. First if all is attention. We can more easily feign attention of listening, while you are much more limited in sign language. This allows for more concentrated 'talking' with sign language. In addition, such a society is more likely to notice a lack of attention, making pauses and breaks important to sign language. They resume when attention can be focused again. This helps in getting a point across better. Teaching might look at a disadvantage, as you can probably service less people in a classroom as a teacher. However, this would lead to more teachers and thus more personal and intensive teaching. But the shortcomings of language can also increase the importance of language. An example. If you're hunting a large predator or other humans it is extremely important to know what needs to happen beforehand. That means they would improve their language skill as a consequence. Then during a fight where any plan can go right out the door you need to be able to communicate quick and clear what needs to happen. Without a voice and possibly with one or both hands full you would be hampered. So with as few short 'words' you need to be able to communicate. Most probably claps of hands or weapons in certain ways. Interestingly the best way of communication in many close quarters fighting is silent, often up until the moment you engage. The language has shortcomings that can be overcome by a surge in communication. This can be compared to an earlier time where many human tribes had a less vocabulary. Out of necessity you create new words to describe and talk. If the necessity is greater there is a larger chance of evolving the language. That is not to say they will succeed. The shortcomings will at first work against them. It'll take quite some time before it can work in their favour, but at the very least they are more likely to grow their language skills faster than a spoken language out of necessity. At a later time they will reap those rewards. [Answer] Locked. Comments on this answer have been disabled, but it is still accepting other interactions. [Learn more](/help/locked-posts). The more technological a society becomes, the less a spoken language matters I don't know about you, but the further along my educational road, the less a spoken voice mattered. I had lots of textbooks, research on the Internet, math and graphing programs, circuit design and simulators... Need I go on? Things were already visually symbolic. In fact, here we are sharing ideas with nary a phonon in sight. And those aspects of my education that depended on the spoken word (study groups and lectures) could have been trivially converted to sign language. I can't think of any reason at all why sign as a primary — or even the sole — language would stop a society from becoming as advanced as any other. I can tell you one other place it would be an incredible benefit. Sports! Specifically baseball... no more "Hey! Batter, batter, batter!" distractions. I'm right, right?! Think about it. And now that I think about it, theatre might become visually amazing. We humans pride ourselves in the expressiveness of our dance... but can you imagine how breathtaking a stage production would become? It gives a whole new meaning to "body language." And what's really amazing is if a soceity evolved based on it, it would be as natural and as capable as any other language. Don't be fooled by what its limitaitons might be compared to our evolution based on sound. Knowing no other way, they would be as capable as we. I wonder how that would affect the development of their peripheral vision? [Answer] The only shortcoming I can imagine for a pure sign based language is that it will not allow communications in situation where there is no visibility between the sender and the receiver: for example the darker hours of the night or a situation in which they are not looking at each other. I think that it is severely limiting: if a bear is attacking you, your and your companion's attention will be focused on the bear, not on your hands so you won't be able to help each other with directions, or if you are walking in line and you are leading the line you have to decide if you want to keep your attention to the path or turn around and talk with your team, nor your followers will be able to warn you of any danger coming from behind. Or during a fight you will have to pick between using your hands for fighting or communicating. I doubt such a limited communication will help advancing easily. [Answer] # Sign language is a language Any transfer of information that happens orally can happen with sign language, new words and grammar can and have been added to sign languages around the world to keep up with modern technology. Furthermore, the in an advanced modern society most information transfer is written or comes with written components. So speaking versus signing won’t change much. Again, sign language is a language. [Answer] The short answer is: absolutely. For a longer answer it's important to call out that there's likely some unnamed bias in the "as advanced as..." standard, because "advanced" is not a technically specific term. What would likely happen in the event of a society who, for whatever reason, had no audio-channel means of communication and their primary language was hand-sign, is a divergence of technological development. If you're needing your hands free to speak, things like automation or alternatives to hand-tools become VERY much more important and likely a hard-focus for that society. Communication at long distance will look very different, with SMS or telepresence being likely initial targets. The advancement of technology is an emergent property of knowledge and communication. But there would be technological sectors that simply held little value for a culture that did not make noises to communicate with one another and so would be considered "primative" or "underdeveloped" by societies for whom such technologies held value. And on the flipside, there would be technologies that such societies would develop as part of their natural inquiry which would have voice-speaking societies scratching their heads and saying, "They do what with WHAT? HOW?!" [Answer] ### They aren't limited to sign language Frame challenge: Homo Mutus only lacks a voice box - that does not mean their only option is sign language. Although they could develop a society with only sign language, and probably would use it for their primary language, you have more storytelling options than that. Sign language has the drawback that you can't yell to get someone's attention, and you can't communicate around corners. Homo Mutus people wouldn't exactly need to do those things, but they would certainly be nice to have, particularly in combat. They aren't deaf, they just lack a voice box. Therefore, although sign language would be their primary mode of communication, they might use musical instruments to communicate over long distances or when the other party can't be seen. Horns or drums might be simple, loud, practical options for long-distance communication, particularly in wartime or in the wilderness. (You don't need a voicebox to blow air into a horn; you just need the ability to control your exhalation). They could develop a musical language based on one or more of these instruments, supplementing their sign language. It could be like Morse code. Indoors, people might use it to call people to dinner by clacking a spoon on the wall. Outdoors, they would use proper instruments to call over long distances. (By the way, what about whistling? You don't need a voice box to whistle, just control over your breathing, tongue, and lips, but it does seem to break the spirit of "Homo Mutus." Perhaps you can just say that they don't have the necessary fine control of their lips and tongue.) [Answer] Of course. In addition to sign language, they could also be able to communicate the same ideas we can using instrument base languages like [talking drums](https://www.google.com/url?sa=t&source=web&rct=j&url=https://en.m.wikipedia.org/wiki/Talking_drum&ved=2ahUKEwiCrsLQttT6AhX3ZTABHUvZABgQFnoECDUQAQ&usg=AOvVaw0yU0BF4suLdYc5Lff9YaOj). Talking drums can allow someone to communicate with someone else over four to five miles away according to the book Interfaces of the Word: Studies in the Evolution of Consciousness and Culture by Walter Ong. There is also [Silbo Gomero](https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.gomeraactualidad.com/articulo/la-gomera/asociacion-cultural-silbo-gomero-ultima-preparativos-decimotercer-cumpleanos/20220921210255031411.html&ved=2ahUKEwiQ3Yfjt9T6AhWoSDABHTrrAIIQxfQBKAB6BAgJEAI&usg=AOvVaw3Bjw6NoxRqCw90B_JvtzbQ), a whistling language where people communicate simply by whistling in different pitches and tones at different intervals. People have been able to use it to communicate over distances of four to five kilometers, so even without spoken language, your version of humanity would still be able to communicate for long distances, especially since whistling would not require a voice box: just the ability to blow and properly pucker your lips. [Answer] Devil's Advocate answer: No. (Or, only with written language also.) A lot of answers here are saying yes, and for good reasons. However, to play Devil's Advocate, I believe there's also a compelling case for non-vocal human beings never achieving the same level of advancement. Sign languages can be equally complex as spoken languages, and the barriers of use in certain contexts are likely not sufficiently high as to make it practically inferior to spoken language. However, spoken language was not by itself what catapulted human beings to the top of the evolutionary ladder. Written language may have been more important. You could definitely get to the Agricultural Revolution without written language, but I'm not convinced you could get much further than that. You mention Homo mutus uses "sign languages and written languages", and I think it's worth focusing on this second component. Sign language itself is difficult to write down (though there are ways). You could perhaps end up with an ideographic language representing ideas with characters, but language (even written language) is cognitively understood through phonological encoding (or in Deaf people, through an analogous process, which is why finger spelling is important) and thus must fundamentally be structured in a phonological hierarchy. Keep in mind that what makes human beings advanced is our cooperation. We use stories and collective fictions to surpass the Dunbar Number (the 150 people in a tribe that you can know simply through everyday interactions). We're capable of cooperating with and trusting other human beings in neighboring villages, simply because they share the same beliefs with us and can communicate productively. This is very important. Equally important as shared belief systems is a use of writing far more mundane, and that's record keeping. It's easy to overlook the effect that record keeping has had on civilization, but no sufficiently large and complex political body could exist without the capacity to keep and preserve detailed records. Record keeping, resource tabulation, mathematics, and so forth, are of the utmost importance. An economic system cannot exist without a written language capable of keeping records. Yes, a barter system works to a certain degree, but is impractical when scaling upwards. Small groups can survive with barter alone. For entire civilizations, it is generally beyond impractical. (Barley coin--despite not being a coin--was decently successful in Babylon, and other cultures have used rice and perishable goods as currency, but even this requires systems of measurement and records of transactions and monetary equivalencies.) In summary, it isn't spoken/signed communication that's important for advanced civilizations (which is not to say it's trivial), it's written communication and record keeping. ]
[Question] [ My setting is more Space Opera than science based, but I am attempting to keep a consistent set of rules for space travel. I'll try to narrow down my question to a "lowest denominator" for the benefit of Worldbuilding–SE. In an otherwise unpopulated solar system, can I detect the arrival of another spaceship? I'll have a variety of engine types in my story, but I'll omit their specifics for this question and ask that you imagine "common" sci-fi tropes. My constraints are: * Detection within the solar system only (in Star Trek they inconsistently "scan" ships that are light years away in other star systems. That seems ridiculous even for space opera) * All engines are "noisy". There is no special stealth technology. This one is braking from FTL and probably the noisiest it will get. Decelerating from interstellar speed to in-system speed takes days from the point of view of the traveling ship, longer from the point of view of an outside observer. (Traveling star-to-star takes weeks, if not months). * Ships range in size from cargo freighters to battleships. Compare roughly to modern ocean ships plus space engines. (The ship I need to detect is a military destroyer, not enormous like a colony ship, but large engines and heavy armor) * The "listening" ship is in the inner solar system orbiting the star. I have made no decisions about the composition of the solar system other than it is uninhabited. * The scenario is a one-on-one showdown between two ships. The "listener" has arrived early and is actively attempting to detect the other ship. As you see, I am aiming for making it easy but I leave the method of detection open. I realize that asking if something is "possible" in Space Opera isn't a valid question, but what method(s) can I use to detect the ship? [Answer] > > This one is braking from FTL and probably the noisiest it will get. > > > It mostly depends on the drive's characteristics (for most "realistic" drives the answer is a definite YES). * You might get the equivalent of a [Cherenkov](https://en.wikipedia.org/wiki/Cherenkov_radiation) flash - a huge blue-white flash when the incoming starship hits an "interface" with an apparent speed equal to the speed of light in vacuum. * And/or you could see the Doppler-shifted radiation of the braking starship in the form of a long-duration gamma or X-ray burst. * the excess energy might be partially radiated as a distinct gravitational wave signature (large detectors possibly required) due to the collapse of an Alcubierre-like "twisted space" bubble. As noted in the comments, a true Alcubierre drive will not cause a sudden grav wave, but it will still give out [the equivalent of a gamma ray burst, or worse](http://sydney.edu.au/news/physics/1737.html?newsstoryid=8801). * a gravitational ripple is to be expected no matter what, since a FTL object can't interact with matter (not even gravitationally) without violating general relativity (essentially, going FTL must remove you from the observable universe). It follows that when the ship re-enters the sublight universe, it will appear instantly as if from nowhere, generating a very small grav wave packet with a wavelength equal to the ship's depth as seen from an observer. The observer might need to deploy a complex array of detectors to be able to observe the emergency - probably a network of sensors connected by laser beams, similar to [LIGO](https://en.wikipedia.org/wiki/LIGO). * if the vessel brakes using conventional means (mass expulsion, or even better from the ambusher's point of view, photonic thrust), it will shine like a nova in several frequencies, possibly even visible light. To detect that, you need a suitable space telescope with very large aperture, or many such telescopes. Being already in space, and having cold and vacuum readily available, will allow the listener to deploy very sensitive devices at next to no cost. # Attempt to stealth To approach a solar system as stealthily as possible, after tweaking the propulsion to the nines, the newcomer would probably try and approach along a [geodesic](http://mathworld.wolfram.com/Geodesic.html) between the brightest or noisiest astronomic phenomenon and the likeliest position for the ambusher (or the local star). This is the equivalent of ["coming in from the Sun"](https://en.wikipedia.org/wiki/Dicta_Boelcke#1._Try_to_secure_the_upper_hand_before_attacking._If_possible.2C_keep_the_sun_behind_you) for starships. To counter that, an ambusher would need to deploy farther from the Sun or use remote sensor platforms, which suffer from lightspeed lag. Of course, if the newcomer's disturbance is too strong, too misaligned, or too unlike the noise from the far star or astronomic object, this manoeuver is pointless and the advantage goes completely back to the ambusher. Braking could be attempted using a solar sail with the highest possible absorbance; it will give only 50% of the thrust of a maximum reflectance sail, but it will be way more stealthy. Infrared emissions will still be a problem; heat would need to be collected and dumped at right angles from the approach vector (less than 90° will contribute to braking but risk detection; more than 90° will supply [an acceleration](https://en.wikipedia.org/wiki/Pioneer_anomaly#Explanation:_thermal_recoil_force) and increase detection risk from [Gegenschein](https://en.wikipedia.org/wiki/Gegenschein) scatter). [Answer] Oh yes! A braking rocket at relativistic speeds putting out enough thrust to do the job will be a rather bright object in the night sky. If it’s the only one, not a sky full of activity, it will stand out like a comet. [Answer] This may be considerably harder sci-fi than you want but from a realistic point of view: there is no stealth in space. I'm drawing quite heavily from [Project Rho](http://www.projectrho.com/public_html/rocket/spacewardetect.php) which is my go to resource when I'm gaming out a sci-fi scenario. Essentially anything human (or sophont) made is a point source of energy that stands out against the galactic background. * Any radio signal will stand out like a sore thumb (for context the voyager 1's 20 watt radio signal is easy to pick out). * If it's not actively transmitting then it's still producing radiation such as heat and any radiation associated with your drives. * Finally just optically scanning the sky is a valid method, a computer today can do it in three days. You probably don't want to use active sensors (radar or ladar) as these systems fall afoul of the inverse square law and have a limited detection range while making you stand out. You are going to get detected but there is no point in making it easy. You would only want these sorts of sensors for close range, high precision, detection. [Answer] You've already stated that there is no stealth in space. Good. Anyone who wants to counter that can find an answer [on this question](https://worldbuilding.stackexchange.com/questions/23313/stealth-in-space-how-realistic-is-it) explaining that no Jimmy, there is no stealth in space. So rather than to answer your question of how to detect another ship in an empty system, lets ask how you remain hidden in such a scenario. We've already determined that it's not possible, so lets ask that question anyway. Answer: don't point your drive at the person you're hiding from, or if you do, make sure there's something else between you and them. Voila. Now you know how to detect another ship: its drive is pointed at you (or at least, in your vague general direction) and there isn't anything between you and them. How visible is it? Well, there's a nice link from the above question that states that "[a single attitude control thruster of the Space Shuttle can be detected at 15 million km range and using main engines it can be detected from Uranus. With current technology.](https://groups.google.com/forum/#!topic/rec.arts.sf.science/-E6r2F8rgnQ[151-175])" Mind, current technology scans the sky very slowly, but pointed in the right direction it'd know. Oh it would know you were there. And how fast you were going, in what direction, and how much acceleration you had (and in what direction), and could predict your course through the solar system (to within some degree of accuracy, not due to the ship or even to the light-time delay, but rather due to the N-Body Problem). Beef up the detection tech in your story so it's got the same resolution as current tech, only it scans faster, and ta da. The TV show [The Expanse](https://en.wikipedia.org/wiki/The_Expanse_(TV_series)) has done an amazing job of being Hard Sciency about space travel and communication and detection thereof. The only unreal thing about it is the engines, capable of providing upwards of 10G worth of thrust on virtually no fuel (which, if we're being frank, is the major limiting factor to our civilization's colonization of the other planets). Oh, and there's the... > > aliens and the alien tech that does apparent magic. > > > But it's not terribly relevant to this answer. Every instance of stealth in the show has been done under a hard-science approach: decoys ("this isn't the ship you're looking for, sorry!"), flak clouds ("sure, you see us, but can you pick out which 'us' is the right one amidst this cloud of radar jamming junk?"), or pure gravitational assisted flight (if no one knows to look for you and you don't fire up the GIANT GLOWING TORCH BEACON OF LOOK AT ME I'M MISTER MEESEEKS then you can drift around the system at your leisure and be impossible to spot). The gravitational stealth approach in the show had a 45 second slice that broke my suspension of disbelief, as Alex came around the curve of a moon, spotted a Martian vessel and was able to reverse course without being spotted. He was still using the attitude control thrusters, but they appear in the show as gas-vent propulsion, not torches, but the part that broke it for me was that he was able to abort his trajectory enough to slip back around the horizon. Honestly they should have omitted that scene. The quip about "oh yeah, the moons hide them from us too" is clever, but that's the only purposed it served. [Answer] I'd say yes; in the scenario the listening ship can set up sensors that are literally miles long; like the gravity wave sensors that have recently made headlines. Think, as an analogy, about motion detectors used in alarm systems: They have a pattern of data they are sensing, the electronics are very simple and do not "interpret" this pattern to figure out what it means: The key is they can detect if it changed, and that sets off an alarm. Your waiting ship needs to do something similar; say with gravity waves, radio waves or just plain light (including infrared, or red shift (different if something starts moving fast), etc. Once you know something is different, you can narrow down precisely where it is different with more effort or analysis. So your listening ship can deploy a few dozen relatively inexpensive sensors in the sphere of concern; covering all sides of the sun and planets so nothing can use them for cover coming in; and those that detect change can help pinpoint the general direction and distance of a disturbance, then you can train the big telescopes on that vector. [Answer] I think the answer to your question is yes, because as you are already defining the technology for FTL travel, it is reasonable to assume that you will be able to define the detection technology. If your ships are capable of FTL flight, they will need significant sensor range to avoid unmapped obstacles and this leads me to believe that the detection technology should be available. Your concern will come with military tactics. I would assume they know approximately what direction the aggressor will be approaching from and sensors, dropped detection bouys, etc. would work fine. But what if the military expected this, overshot the star system while scanning it, braked in the next one and approached from the opposite side of the star and slower than expected. In your design, I would expect sensors to work well toward the direction of travel, a 360 degree view of a star system is a big task, and the opposite side of the central star would be a blind spot without a sensor relay. [Answer] Two visual telescopes separated a little bit apart and a computer can calculate the speed of any moving object they can see. There are some blind spots like a star of the system or planets, but they could be overcome with additional telescopes. Even now the telescopes from Earth can see a planet 1200 light years away. ([link](http://www.sciencealert.com/astronomers-captured-this-amazing-photo-of-an-exoplanet-that-lies-1-200-light-years-away)). The telescopes just need to move across the sky very fast to cover all the sky in a pretty short time. There is a problem of differentiating between a ship, an asteroid or a comet if they have a small enough speed. If I remember right current aviation radars hardly differentiate between a plane and a flock of birds. Birds just don't fly at 900 km/h. High resolution telescopes can just show a photo of the object. It is beyond current tech, but sensitivity of current cameras is increasing extremely fast. There are some methods used currently that differentiate the composition of space bodies, but I do not know the details. ]
[Question] [ How to justify evolving pointy ears that stick out from your head, on a humanoid. Like this: [![Alfar Slapparsdottir](https://i.stack.imgur.com/ko1EL.jpg)](https://i.stack.imgur.com/ko1EL.jpg) --- They can either start from the usual round-eared human(oids) with ears close to their heads, or have a different evolutionary path than humans, but in the end, they must end up being basically "humans, but with pointy ears sticking out.", in at least physical and mental ability if not coloration, skin, fur, etc. Also, the ears... Should work like ears. Yeah. Also, fully organic, no metal robots that basically just are wearing a skin-suit or anything. [Answer] It's required for locating sounds in the vertical plane and increased sensitivity. Without [pinnae](https://en.wikipedia.org/wiki/Outer_ear) humanoids could not localize sounds in the [cone of confusion](https://en.wikipedia.org/wiki/Sound_localization#The_cone_of_confusion). The pinnae alter incoming sounds subtly in a way that allow us to determine the orientation of sounds. Two ears are required for determining the time difference between arrival times of a sound, which tells us which side of the head sounds are coming from, but without the pinnae, we couldn't tell much more than that. They also act as a sort of funnel for sounds. [Increasing the incoming sound pressure](https://en.wikipedia.org/wiki/Outer_ear#Function) to the ear drum. The evolutionary advantage comes from being able to tell if that predator sounds just came from above you or in the bushes below you. The different shape might allow increased distinction for localization as well as increased acoustic sensitivity. [Answer] [Sexual selection](https://en.wikipedia.org/wiki/Sexual_selection). There was a group of humanoids who thought big ears looked good, the humanoids with the biggest ears bred the most, you had a second generation with slightly larger ears, the ones with the pointiest ears bred the most and so on. Note that you will have to isolate the population somewhat for a significant period of time in order to have a particularly noticeable effect. This is a relatively minor change, but evolution is never fast. [Answer] Humans already are able to have ears halfway there. > > In most people, protruding or prominent ears are caused by an > underdeveloped antihelical fold. When the antihelical fold does not > form correctly, it makes the helix (the outer rim of the ear) stick > out. ([ref](https://www.chop.edu/conditions-diseases/protruding-ears)) > > > [![enter image description here](https://i.stack.imgur.com/0j0xy.png)](https://i.stack.imgur.com/0j0xy.png)[![enter image description here](https://i.stack.imgur.com/bPive.png)](https://i.stack.imgur.com/bPive.png) Ears that look like this work just fine. The only reason to "fix" it is aesthetic (children are often teased). Even the doctors refer to it as "bat ear" or "Dumbo ears" on their websites. If you want an even less developed antihelical fold, it would be well within the limits of human evolution to achieve. Just select for it. Any reason that gives people with this type of ear more of a reason to reproduce will work. It can be direct (person is more likely to have sex) or indirect (people with protruding ears get all the best jobs and are therefore more likely to find mates...may or may not work in any given culture but...). Elongating the helix is a more difficult change. But there is a genetic condition called Stahl’s ear (aka Spock's ear) that does this, pointy top and all. > > Stahl’s ear is the result of misshapen cartilage. It is characterized > by an extra horizontal fold of cartilage (crus). Normally, there are > two: superior and inferior. In Stahl’s ear, there is a third > horizontal crus. The helix (or upper portion of the ear) may unfurl, > giving it a pointed shape. This gives the characteristic “Spock” > appearance to the ear. ([ref](https://www.chop.edu/conditions-diseases/stahl-s-ear)) > > > [![enter image description here](https://i.stack.imgur.com/a5yux.png)](https://i.stack.imgur.com/a5yux.png) Again, there is no different in the ability to hear or anything else. It's all about looks. And looks matter. The ears you want can happen with just two changes to the standard ear. Select for these and you're golden. But why would these be selected for? Other than considering them sexy (the sort of thing that usually changes in a few generations, if not sooner), what justification could there be for picking one type of ear over another? And the answer may be, there's not much. Because these types of ears don't cause harm (or benefit) or change hearing, which type moves forward as the standard ear is more about the luck of the genetic draw when a group of humans is small and isolated then grows quickly. Imagine an extended family (a few hundred people), where both these genetic variations are common, migrating to a new land. Then the people on the old land are mostly wiped out. The species continues to grow from the migrant group, incorporating a few survivors from other groups. Add some sexual selection into the mix and whoa! elf ears! [Answer] If being able to carefully focus a specific frequency band of sound was critical to survival (avoiding predators or other natural enemies, or being better able to seek out a food animal), this would also preferentially select for a given ear shape and size. [Answer] Here is a story based on your question: In the heart of the dense Taryllis Forest, a civilization unlike any other took shape. Here, among towering trees and sprawling undergrowth, evolved the Veridien, a species very much akin to humans but for their distinctively pointed, protruding ears. The Taryllis was a cacophonous world of noise. With so many species, each with its distinct sounds, survival within the jungle depended on one's ability to distinguish between the subtle nuances in the cacophony. Over time, this selective pressure favored those with larger, more pointed ears that were better at catching and identifying these sounds. This was the first step towards the development of the Veridien's unique ears. The ears of the Veridien, unlike human ears, could rotate and move independently, similar to some terrestrial animals. This adaptation, combined with their natural shape, allowed them to precisely pinpoint sound sources, a necessary skill for hunting stealthy prey and avoiding the numerous predators lurking in the shadows. However, survival was not the only factor driving the evolution of the Veridien's ears. In their society, the ears played a crucial role in communication and courtship. Unlike humans who depended heavily on facial expressions, the Veridien had developed a complex language of ear movements. An excited flicker, a slow droop, or an abrupt fold - each movement was rich in meaning. Over the millennia, sexual selection took hold, favoring Veridien with larger and pointier ears. These were seen as attractive, a symbol of genetic health and strength. The ears became an integral part of their identity, a signifier of beauty, much like the peacock's tail or the lion's mane in other species. The Taryllis Forest was also a brutally hot environment. The Veridien's protruding ears served as a natural cooling system. An intricate network of small blood vessels running close to the surface of their ears helped dissipate heat effectively, much like the large ears of an elephant. Evolution is a game of survival and adaptation, and the Veridien played it masterfully. Their pointy, protruding ears were not just an appendage, but a testament to their resilience and adaptation in the face of constant evolutionary pressure. They had become, in essence, "humans" of the Taryllis, their physical and mental abilities honed by their unique environment. But nature is an ever-evolving stage. What works today might not work tomorrow. As the Veridien looked to the stars and dreamed of exploring new worlds, they wondered how their distinctive ears would fare in environments wildly different from the Taryllis Forest. Only time, and evolution, would tell. ]
[Question] [ Somewhere out in space, we stumble upon an alien device. It is immediately taken back to base or Earth or wherever and given to scientists to investigate. Reverse engineering the device reveals that it's fairly simple to duplicate, and it can be used to greatly simplify some process (in this specific case, FTL transportation), but the scientists are completely baffled as to how the device is able to do what it does (and in fact, all records indicate that the aliens discovered how to build it by accident). The people in charge of the operation aren't phased by this, however, and immediately begin mass production of the device. How long, depending on the complexity, is it reasonable to assume that the physics behind such a device could go unexplained? With the whole human population—and specifically, all human entrepreneurs—exposed to fully operational replicas, I can't imagine it would stay this way for long. But what if I made tampering with the device to set up scientific tests difficult (e.g. remove or modify any one piece and it won't start) or dangerous (e.g. add another wire for debugging and turn it on and suddenly your insides are your outsides)? How impossible or fatal (or both) would I have to make it to have the device stay unexplained for 50 years? 100 years? Indefinitely? And how would this affect its use or marketability? [Answer] I think it's dependent on how we can go about constructing more of the device. Anything that we can construct, we can reverse engineer and study the parts of. We can trace how our technology produces an unknown effect, modify how we do that, and learn its parameters. In this case, it wouldn't take long after we start mass producing the device that we can figure out how it works. On the other hand, what if the alien technology that we found allows us to create more of the alien technology? We start with a device that contains some warped chunk of space. The warped chunk doesn't fit in at all with our understanding of physics, but with some technology that we do understand, we can pump energy into it and create another warped chunk of space. These chunks, when used in a different way, allow us to travel faster than light by warping space around them, effectively letting us set up an Alcubierre drive. If this were the case, with the alien technology being required for the full manufacturing loop, there isn't a point in the process where we actually know or understand what's going on. It may be that doing so isn't even understandable based on how we as humans experience the universe. For example, what if the chunks are actually 5-dimensional, and mostly interact with a portion of the universe that doesn't intersect ours? We might not understand how they work, because we only see a tiny cross section of where the chunk intersects our reality. In this case, the answer could be once humans transcend the true nature of the universe, which could be thousands of years later, or never. [Answer] It could be incredibly simple to make and yet completely unfathomable. Example We could be given a lens or antenna that focuses energy from a dimension or stream of particles that we haven't discovered and don't have the technology to detect or produce. For example in our own world it's possible to make a working radio antenna out of damp twigs. The device acts as a transducer and converts the (undetectable to us) rays into a form of energy we know about - heat for example. What we don't know and can't detect is the nature of the incoming energy. We just know that if we point the antenna in a certain direction, (say a particular star system) it outputs heat (or whatever). The principle is similar to public-key encryption. Anyone can encrypt a message but only people with the decryption key can decrypt it. [Answer] What do you mean by unexplained? This is a serious question. One can pretty much say that the fundamental laws of the universe are those which we cannot explain. Some may later prove to be explicable in terms of more deeply fundamental laws as yet unknown. Others may remain forever inexplicable, bearing much the same relation to physics as axioms do to mathematics. So far this reductionist approach has resulted in things of technological use being explicable right down to entities so small that just accepting them as given bothers only the physicists trying to find an ultimate theory of everything which may or may not exist. Some hitherto overlooked macroscopic property of matter or energy that does not have an explanation in terms of the underlying entities seems ... unlikely. The least understood fundamental is gravity. If you have visiting aliens that implies FTL travel which is immediately an inexplicable observation. FTL breaks down into causality-violating and paradox-creating actual motion, and wormholes or jump-drives which suggest strongly that gravity is far more capable of manipulation than we believe. Speculating further: what they've accidentally left behind is a wormhole-connected interstellar access thingy. We don't understand it because it's the most accessible tip of a huge gravItic-tech pyramid like a mobile phone is the accessible tip of a global network. The bit that does the real work is ... elsewhere. Soon, we're using that tech like swallows use the telephone network. The aliens were using it like arts graduates use mobiles. The types who set their passwords to 1234. And somewhere out there, a bill will soon become payable. [Answer] In your universe, you could be talking about some device that exploits as-yet-not-known physical law, or even a device that exploits a flaw in the universe's operating system, so to speak. In the first case, it would probably be a matter of time before the operation of the device may inspire a line of research that led to a discovery that explains its operation, though whatever time would be up to you as the author. In the second case, there may not be a reasonable explanation why the device works as it does. In such a case, it may not ever be explained, and researchers could waste a lot of time and resources in futile efforts to understand it. [Answer] A misconception can hide the real working principle for millennia. The sundial was misunderstood for at least 3000 years, if you count from egyptian shadow clocks (1500 BC) to heliocentrism (1543), but it is likely that people have been sticking sticks and stones in the ground for timekeeping purposes much longer (consider Stonehenge), presumably without grasping the mindnumbing thought that the Sun's apparent motion is just apparent and it is the ground that is rotating. [Answer] Consider that most of society will not be trying to figure it out. If it is so easy to reproduce, most of society will be busy trying to make money selling them. Honestly, it could be a very long time. "Any sufficiently advanced technology is indistinguishable from magic," if I may quote Arthur C. Clarke. It would not be unreasonable to compare such a magically complicated device to organics. We've been trying to figure out what the human form can do for centuries with limited success, even though we know how to pop one out with as little as 9 months lead time. [Answer] from the example that we know for sure (humanity), the answer for how long could a technology go unexplained physics-wise (rather than a device) is hundreds of thousands of years. the primary example is fire. cro-magnon, neaderthal, heidelbergensis and even erectus used fire for a long, long, long time. according to the wikipedia article on fire, and i checked a couple of the sources, evidence for cooked meat goes back like 2 million years, and controlled fire is at least as old as cro-magnon (who is, biologically, us). fire is a technology, and although its use, and even its creation has been known and practiced for a long, long while, the underlying physics, what with the atoms and the frantic motion and the thermal dynamism produced therefrom have only been known for what, a few hundred years. and that's being generous. so it's possible the underlying physical reality of a technology could go unknown or misunderstood for millions of years. and that's, like, a historical fact. [Answer] Quite a long time. But, you would have to make it both interdependent on every part (thwarting learning things / reverse engineering by building partial copies / removing portions of full machines, substituting parts/materials), and probably powerfully dangerous. Simple danger to individual humans probably won't cut it. There are plenty of disposable (as well as insane and/or suicidal) people around: criminals, political prisoners, etc. to throw at simply dangerous machines. Things which blow up significant portions of the planet, or make the space-lanes less habitable, will not get blown up as often. And that's if the alien device is not part of the manufacturing process. I personally think the 'warped space' solution is the best - if you want it to always be a conundrum. If you eventually want someone to solve it, you just need to make it a matter of supreme luck to decipher it, and it can last a damn long time. But, to be believable, it should use something other than just simple arrangements of masses of atoms, as we can examine those quite well remotely. Something that's small enough that Heisenberg applies, or some other type of force-field / multidimensional access point. Heisenberg would be interesting, especially if we didn't know how we were manufacturing stuff: an X percentage of the production run wouldn't chance to be correct, and would come off as duds. Which would keep the price of the items way up, since you have to produce a lot of them in order to get one which happens to work. You can't look at it to see if things are in the correct state, you have to put it together blindly, and hope for the best. [Answer] ## It could well be impossible to understand. Consider the possibility that we are in a Matrix-like computer simulation. This is a well debated philosophical problem and the thing is, we cannot prove that we are not in such a simulated world. Now, imagine that in the simulation machinery there are some admin-codes hardwired into the system. Maybe they are accessed by drawing certain symbols, arranging certain objects or whatever - and when detected they somehow change the simulation. Scientist discovering such a code, in the form of a set of simple rings that when electrified opens a gateway to somewhere far away, will be able to reproduce and mass produce the item. The explanation on why and how it works however can literally not be found in our universe. Now this is just a thought experiment - this applies equally well if our layer of physical access to reality is in some other way separated from a higher physical access to reality, The Matrix is just one example. The point of this is that it is entirely possible to find a technology we could never understand. [Answer] We already have devices like that and we are unable to explain the idea behind them. For instance, we don't know how exactly quantum teleportation works but we have microscopes that exploits it. We have no idea about how quantum entanglement works but we build quantum computers (search D-Wave) that relies on them. ]
[Question] [ I'm interested in writing a story about inhabitants of a permanent base on Mars, a few decades after all life on earth has (presumably) been wiped out. Preferably, I'd like them to still be there, be it with a major setback in technology. In the interest of keeping the community on Mars more relatable, I'd like the story to be set not too far in the future. Assuming this is set in our actual solar system, at what point is it plausible that we could have built a (almost) self-sufficient base on Mars and what could have been the motivation of the people doing the colonizing? [Answer] According to [Robert Zubrin's "The Case for Mars,"](http://en.wikipedia.org/wiki/The_Case_for_Mars) we could have had a mars base right now. What has stopped us (humanity) from colonizing mars, according to Zubrin, is our lack of focus on space exploration. If we had retained the same enthusiasm for exploring space during the Apollo Missions, humanity would likely be on Mars by now. This book was written when the space shuttles were still around. Of course, there are new players in space, such as [SpaceX](http://en.wikipedia.org/wiki/SpaceX), who may just decide to go ahead to Mars while the NASA looks on in extreme jealousy. (Not that NASA couldn't match their expertise, but merely lack the directives from presidents to go.) We could easily see a manned mission to Mars within our lifetime, possibly even the beginning of a colony, depending on who goes there and what their end goals are. The best explanations as to why we can do this are detailed in "The Case for Mars," especially when it talks about [Mars Direct](http://en.wikipedia.org/wiki/Mars_Direct). [Answer] I don't believe my own answer but [Mars One](http://www.mars-one.com/) claims that they will send up the first colonists who will live the rest of their lives there in 2024. While it will depend on delieveries for maintenance items, this is very soon. If funded and supported, one would expect the technology we currently have would allow us to make it self sustainable within 20 years after that. I am not fully convinced, however, that their predictions/plans are reliable. I also do not believe that they will be able to make it completely self supported. Please note that mining and agriculture are very necessary for a physical structure to be build/repair itself and that is going to take time to setup. While the computer systems will reasonably be able to be replaced via shipments, the eventual colony would need very advanced manufacturing inorder to construct these replacement components. This is by no means a simple goal and it would require many people to operate. [Answer] The excellent book [Red Mars](https://en.wikipedia.org/wiki/Mars_trilogy) from Kim Stanley Robinson deals with the history of the first colony on Mars. It was written as immediate future in 1993 stating that the trip happened in 2026 after an agreement between the USA and Russia and the joint participation of (Almost) the whole world. In fact, we could be there now (2014) if we had continued sustaining the space programs after Moon landings. [Answer] I think your answer is going to depend on the situation on earth. At our current rate, 2050 isn't that feasible...to be blunt, we just are not dedicating many resources to it as the return just isn't there (ultimately we are a capitalist society, space exploration and colonization doesn't exactly result in a good payoff to investment ratio). I'd say if the Earth remained how it currently is, 2100 is probably a reasonable goal for it. I don't like the mining colonies btw...Meteorites are far more easily mined and don't need to be shipped off a planet to get to it's destination. Colony (food growing/supplying/people living) on Mars is a more feasible reason to be there as Mars is ultimately a stepping stone towards the asteroid belt and other space mining opportunities there, as well as a gateway to the rest of our solar system. If you are into the mining scenario, consider one of the two moons (Deimos and Phobos) as the ones being mined...Phobos was struck by another planetary body early in it's history and can easily be used as the explanation as to why exceedingly rare elements are found on that moon). Of course, this might be all moot if there is a 'mars space elevator' scenario where what is extracted from mars can easily be put into space for transport. All this said...2050 is also feasible, had the appropriate situation on Earth come to bear. War, disease, destruction, famine...if we need to leave this planet to live elsewhere, the social changes needed to get to space colonization will happen considerably quicker (and also gives the reason of 'need a place to live / colonization' as to why people are setting up colonies on mars). Remember there is no profit in space exploration and our current economic situation flat out means we won't invest in it. Change that social/economic setup so space exploration/colonization is our only goal, and we'll get there basically whenever you feel like setting your story. It's a good position for story writing...give us a reason to have a colony, and we will, regardless of time frames. added: remember we got to the Moon with 14.4 modems in the late 60's early 70's...tech wise, there is really little reason why we couldn't be on Mars now. [Answer] Engineers routinely talk about the difference between what is possible in theory, what can be demonstrated to be possible in the laboratory, what can be done in practice, and what can be done economically. There are lots of inventions that have been built, demonstrated, and really do work, but that are far too expensive in one way or another for anyone to use for any practical purpose. Like, auto manufacturers have built prototype cars that run on fuel cells, meaning that basically the fuel is water. Sounds really great: if we built a fleet of cars that run on water, think how much we could save on gasoline, not to mention cutting pollution, dependency on foreign sources, etc. But there's one small catch: the raw materials for each car cost about $200,000, not even considering what it costs to actually assemble the vehicle. My point being: If tomorrow we all woke up and discovered there was some really compelling reason why we had to go to Mars, if the future of all life on Earth depended on it, the basic technology to make such a trip exists. Engineers would have to work out the details of the design, but I'm 90+% confidant that, if a hundred billion dollars was devoted to the project, and if all the bureaucracy and environmental regulations and political considerations and all were waived or ignored and suitably capable people pulled from whatever they were doing before, we could have the vehicle built and launched in a year or two. The problem is what would give us the motivation to do all that. Given present technology, the cost of transporting one person to Mars would surely be in the billions of dollars. It is difficult to imagine anything they might find there that would be economically productive. Whatever resources exist on Mars, we could surely obtain the same resources here on Earth, or find some way to accomplish the same goal with different resources, for far less money. Despite all the problems here on Earth, it would almost certainly be more productive to devote resources to solving the problem than to escaping it by going to Mars. Consider why Europeans explored and colonized the New World. (a) Looking for a more efficient route to India. (b) Access to gold and other resources. (c) Scientific inquiry and adventure. (d) Political prestige. (e) Escape from religious persecution. With our present technology, economic motives like (a) and (b) are unlikely to be practical. (c) is possible. At present a manned expedition is so expensive that no one is prepared to pay the bill just for the shear joy of discovery, but it could happen. (d) is possible but the political situation doesn't presently exist. (e) is too expensive for any dissident religious group to be able to afford it at present. All that said, my conclusion is that no one is likely to send a manned expedition to Mars until there is some technological advance that dramatically reduces the cost, OR until enough people think the scientific or political benefit is worth the cost. It's difficult to predict when either of those things will happen. I'd be surprised if there's a manned expedition in less than decades, and a true colony would be further away still. Of course for a fiction story, you can invent circumstances to make it all happen. You can just write, "... and then Dr Jones invented the new Fubar drive that revolutionized interplanetary travel ..." or "After the rise of the Islamic Caliphate, the United States and the Caliphate became involved in a space race to see who could reach Mars first. Everyone knew that whoever won would be viewed as the technological leader, and other nations would quickly join their alliance ..." [Answer] I think you need to lay down the urgency first. I wouldn't be surprised if we could have a self-sufficient colony on Mars by 2020 if it was done on a crash-priority basis. (Say, a 20 mile asteroid is detected that's going to smack us on Jan 1, 2021.) It would certainly mean Orion boosters and probably a few spectacular failures. [Answer] 1970s. :) Seriously. If we hadn't scrubbed the space program, we would've done Skylab (in 69/70) as the ISS - or better - and then been on our way to the rest of the solar system. You don't need a lot to make a self-sufficient colony (esp. if you allow a colony complex; ie: high-space production of metals from asteroids). You don't even need microchip fab. We want microchip fab, because it makes life a lot easier. But, old-school microchip tech is within hobbyist reach now. Getting off Mars is a lot cheaper than getting off Earth for servicing high-space production. ]
[Question] [ In this society there is a regular apocalypse event that can cause 80% casualties among the human race. This happens once every 20 years. While this is survivable, it's not survivable if it happens twice in a row. This can be prevented by a prophesied child arising who can stop the apocalypse. This child will be generated among the 5-18 year olds, and they have no current way of reliably predicting who it will be. If the child dies before they fully awaken, the apocalypse happens, and the next generation likely has a much higher risk of death due to reduced resources. The death rate for children then is around [17/1000](https://data.unicef.org/topic/child-survival/child-and-youth-mortality-age-5-24/) and they want the death rate to be as low as possible, while still ensuring that children can train so that the prophesied child can effectively handle an apocalypse. How would a society which wanted to minimize deaths in school age children, make schools? Awakening as the prophesied child cures all diseases, so being paralyzed or disabled is fine. Tech level is modern earth, magic is mostly non existent. [Answer] Short answer: Very military-like Although you don't mention how the apocalypse manifests, I imagine that would be priority #1 for the society to figure out: what keeps happening and why and what can be done about it? Is it fire? Locusts? Comet impacts? The specific details of the apocalypse would greatly inform the way the society reacts to it. For example, maybe everyone is training for asteroid redirect missions because that's how the apocalypses manifest. I think that the schools would prioritize safety, like having tornado shelters, being robust against floods and earthquakes, having backup generators, tools, supplies, communication gear, food and water so that people can heavily fortify to best survive whatever apocalypse awaits them. There would likely be hospitals or health-care professionals on-site in the schools. People would be heavily supervised and their activities strictly controlled so that they do what is required and have a greater chance of surviving. I imagine that survival training and health education along with risk/threat assessment and preparedness would be mandatory skills taught in these schools. So overall it will look quite military in its structure and educational offerings. Dealing with an unknown impending we-all-might-die kind of situation sounds exactly like a how a military prepares. I would hope that everyone in society (not just the schools) would be working on the problem with most people focusing on having skills and resources to survive the apocalyptic events. But again, I think the specific way the apocalypse manifests is of supreme significance. If it's a cabin-in-the-woods-esque spin-the-wheel-and-anything-wrath-of-god-like-can-happen kind of situation, I think your society is likely hosed. (Doesn't stand a chance.) Especially with a whopping 80% death rate. [Answer] Frame challenge: In rich economies (except maybe the USA) schools themselves are probably not a major factor in child mortality. Schools would only be affected incidentally, for example if there's an epidemic, you'd want to keep children from gathering en masse in massive bug distribution centres. The differences would be more on a societal level. For example the idea that it's acceptable for children to go hungry would be anathema. If you advocated for it, you'd be shunned at best, prosecuted or lynched at worst. Same for universal healthcare, anyone against it would be scorned by the rest of society. In fact the age distribution of healthcare spending, now largely weighted towards the older generations, would have to be reversed, spending a lot more on children and their parents. Overall life expectancy would probably be lower as a result (compared to rich societies of our real world) and it's an open question what such a society would do with old folks. There'd be advocates for keeping everyone alive as much as possible (for their secondary benefit to children) and there'd probably be ones who favour a more...radical approach. This could be a major fault line in public consciousness. Not least of all because most discrimination we have in our world might become taboo for similar reasons: you never know where the next "messiah" will be born. The one thing you know is they're not gonna be old, so... These would be the main focus of your society...on a good day. Because if there's anything we've learnt over the past few years, it's that logic can count for very little when many people just want to watch the world burn. So at the end of the day it's up to you how you want to play it. [Answer] Short answer: Keep them in the schools The leading cause of death in the third world are [healthcare issues](https://ourworldindata.org/causes-of-death) (including issues due to contaminated water and lack of food). In the US on the other hand, guns and cars are [most dangerous](https://www.mdedge.com/emergencymedicine/article/191576/pediatrics/unintentional-injuries-top-killer-us-children) to children. Apart from the guns, this is probably representative for the first world. Both issues have the same solution. Governments have to take control of the children's environment by putting them in boarding schools as early as possible. The schools can take care of healthcare, clean water and sufficient food. They can keep the guns and drugs out, keep the children away from traffic and make sure everyone can swim. Apart from this, extensive pre-natal care is probably most effective. Maybe some sort of center were pregnant women stay (don't call it a prison) and get all the care and tests until birth. [Answer] While I suspect the timing and percentage you cite are unsustainable, the way to minimize death in an apocalypse depends on the apocalypse. If the problem is regular pandemics, then obviously we minimize death by keeping the children separate or isolated from the rest of the world, in "clean rooms" with filtered air and away from the public. If the apocalypse is heavy meteor showers, we keep the kids together in a school that is inside of a mountain that can protect them, or a school deep underground and covered with a tough steel shield several meters thick. Much like some of our own nuclear facilities are protected against nuclear bombs. Whether it is isolation and distance or collective protection in one place depends on the nature of your apocalypti. [Answer] ## No Cars, No Guns, Lots of Counselors The [leading](https://www.nejm.org/doi/full/10.1056/nejmc2201761) causes of death for children in the US circa 2020 were: Guns, Cars, Drugs/Suicide, Suffocation (surprisingly high! I assume this is SIDS), and Drowning. (I've excluded Cancer, Heart Disease, and Congenial Abnormalities, since those don't seem "treatable") SIDS doesn't apply to school age children, and I assume most drownings are in unsupervised backyard pools. So that leaves Guns, Cars, Drugs and Suicide as major sources of child mortality that could reasonably be linked to a school environment. ## Sounds Nice So a school optimized for child survival would be gun-free, use safe public transit in place of personal vehicles, and have a lot of support for individual children to help them through the growing up process and keep them away from drugs and suicide. Your apocalypse sounds... surprisingly pleasant. [Answer] A society like anything in the real world would be very much unsustainable. The only way a society might be able to have a stable population, pretty much prevents the school 5-18 scenario. Assuming the timing is more or less stable at 20 years, the only way this could work in my mind is as follows: * There is a very strict rule against reproduction in anything but the first 5 or so years after an event. * This means you will have cohorts that are always a maximum of 4 years apart * Every surviving woman's task after an event is to reproduce to at least the level of stability (so 5 children per woman). Since all of them are at least 15, they are all of fertile age (real world politics simply cannot apply) * Every surviving male's task is to make sure these kids are supported up to the next event and to keep society as a whole running * Anyone that survives two events in a row would basically be "off the hook", they are now leaders, not 'working' class Since schools are basically a rolling system of a single cohort going through the process, there is not a normal school system, but a very subject oriented one. Also since there is a full restart 5 or so years after every event, the form of school will change a lot, depending on local 'leaders' who survived this time around. [Answer] Your premise appears faulty on two scores. 80% cull every 20 years means certain extinction. In a stable population (births = deaths) only 4 in a hundred would survive a second apocalypse. Only 8 per thousand would survive a third. 8 people are not enough to have a golden child that survives long enough to 'awaken' and prevent the fourth apocalypse. Also remember that only a third of the population are of breeding age, and faced with that degree of devastation, survivors won't want to breed. Would you want children knowing 8 in 10 will die? If a school or any other system could be designed to survive such an apocalypse, then that system could be used to protect the majority of the population, rendering that plot point moot. If the majority can be protected, then the apocalypse could could still decimate the population. Decimate = 1 in 10. Now consecutive apocalypses become tragedies not extinction events. Same motivation exists but realism is improved. I don't know what any school designed to protect from all possible deaths would look like, but I am pretty sure it would feel like hell. For a school based story, you could have a selection process that brings potential candidates to a safe location (under a mountain etc.) to a school that is risk adverse to a paranoid level. That might provide a believable backdrop to the scenario you want to explore. ]
[Question] [ This is my first question here, so any help would be greatly appreciated. I am trying to figure out how my world's day and night cycle works, or if something like what I'm hoping for is even possible. I am building this world around multiple random small-scale ideas, so I've been having trouble making them work together with my limited knowledge of astronomy. The world is an inhabited planet that is smaller than Earth, though I don't know the exact size. Possibly around the size of Mars. There is a small archipelago somewhere on the planet (I don't have a definitive map yet), of which the largest island is the only inhabited one, where the main idea is that it is night for a large portion of the year. I know that some places on Earth are like this, but if possible I would like this area to spend more of the year experiencing nighttime than daylight. For example, 9 months of darkness and 3 months of light in summer (I don't actually know what the proportions would be, basically anything that would actually work would be fine as I'm still in early stages). The rest of the planet, or just a section of it large enough to hold the main continent (it has one main continent, that archipelago, and several small continents and many islands that don't really matter) would ideally have either a "regular" day/night cycle or possibly the opposite of the archipelago area. It needs to have a fair amount of daylight, and the archipelago's long nights should seem special. That is what I'm hoping for, but it is still very flexible at this point. For other information on the planet and context, this is a fantasy world (magic exists). Magic could be part of the explanation if need be, however, the magic system actually depends more on this cycle, which is why I'm trying to figure this out first. There are some other planets in the solar system, which has one sun to keep things simple. The focus planet has at least one moon, though it might have more. At some point in the past (a long time ago) the moon was hit by an asteroid or something-again astronomy is not my strong suit- resulting in pieces of debris from the moon still in orbit around the planet. Those are all the possibly relevant details I can think of. Basically, I am wondering if something like this could theoretically work, and if so, how? Thanks! [Answer] Have your planet tidally locked to one star in a high-eccentricity binary system. For most of the year, the main continent faces its parent star and is in total sunlight. The center of this region is a scorching desert, but as you reach the edges (especially the regions that have daily twilight due to the slight eccentricity of the planet's orbit), the climate becomes pleasant. As you venture further into the dark zone, however, convection currents pick up and the weather becomes dangerous. Constant hurricane-force winds block access to the mysterious island, and although they bring warmth and moisture to the region, the clouds they bring block the dim light from the sister star: [![Far Orbit](https://i.stack.imgur.com/Z3cOm.gif)](https://i.stack.imgur.com/Z3cOm.gif) But once per year, the small but bright sister star plunges quickly towards the planet and primary star. The main continent gets brighter, to be sure, but the dark island begins to receive enough light that the winds die down, the clouds clear, and the region experiences several weeks of what we'd consider a "normal" day/night cycle: [![Near Orbit](https://i.stack.imgur.com/z1k3W.gif)](https://i.stack.imgur.com/z1k3W.gif) But this doesn't last. As quickly as the sister sun arrived, it leaves again, vanishing into the distant reaches of space. The island cools, the wind picks up, and clouds darken the skies once again. ## Additional Info: The planet orbits very close to its parent star. This is necessary for the orbit to remain stable in the presence of the sister star, and for its rotational period to be on the order of a day. This means the star needs to be dense but dim. Universe Sandbox has "carbon stars" that meet this criteria, though it required a bit of tweaking. A perfectly circular orbit would mean the star remains fixed in the sky, but a slightly elliptical one means it "wobbles". [![enter image description here](https://i.stack.imgur.com/it340.gif)](https://i.stack.imgur.com/it340.gif) The planet+star orbit a much more massive star in a highly elliptical orbit. This is necessary to get the seasonal aspects of the dark island. When the stars are far apart, the distant one contributes very little energy to the planet. When they are close, however, its brightness rivals that of the main star. [![enter image description here](https://i.stack.imgur.com/Jo9ZA.gif)](https://i.stack.imgur.com/Jo9ZA.gif) The surface can be made habitable by tweaking values; I was able to achieve a temperate climate by melting the ice caps. I don't know how stable such a configuration would be, but in the sim it lasted at least 50 years without exploding or turning into a black hole, which means it's probably close enough to be plausible in fiction. [![enter image description here](https://i.stack.imgur.com/zShm9.jpg)](https://i.stack.imgur.com/zShm9.jpg) [Answer] One possibility is with a highly eccentric (elliptical) orbit, plus axial tilt. The orbits of the planets are mostly circular, so the periods of constant night at the poles are roughly equal to the periods of constant day. But if the orbit was highly eccentric, then one of the poles would spend more time per year pointed away from the star, and and therefore have more night than day. The opposite would be true on the opposite pole. In contrast, places near the equator would continue to have a regular day/night cycle. One major caveat - an orbit with a high eccentricity would probably not be ideal for habitability, with the amount of solar radiation varying significantly throughout the year. So the temperature ranges will be much higher. [Answer] ## Persistent eclipse Your planet has a ring system. The ring's plane is very closely aligned with the rotation plane of the planet around its star, presumably because they all derive from accretion of material from the same disc[1]. As a result, the ring casts a persistent shadow over the planet's equator. One side of the ring is denser than the other, or there's a very slight tilt to the planet's axis (and therefore the ring is very slightly angled in relation to the sun), so that the ring's shadow has cyclical wobbles that leave your equatorial archipelago more exposed for parts of the year, and in deeper shadow for other parts. Landmasses away from the equator would experience no ring eclipses at all. [1] not sure why the ring would remain in ring form if this is the case, maybe it's a former satellite, astronomy people please weigh in [Answer] Are you looking for realistic or believable? I'm not a fan of realistic. It's boring. Believable, on the other hand. That's how you get Tolkien's elves walking on top of snow without leaving footprints. Nimble little minxes. Earth's days can be thought of as fairly equal (at the equator and ignoring seasons) because its rotation speed is substantially faster than its orbital period. In other words, the ratio is more-or-less 365:1. But what if your planet was almost tidally locked in that the rotation of the planet is just faster (or slower, I'm sticking with faster) than the orbital period. Now the rotation is 1.05:1 Simplifying things a bit, you have a night that's one year long followed by a day that's 0.05 year long (in Earth terms, it's 365 days of dark followed by 18 days of light). It should be obvious that you can't get an arbitrarily long night followed by an arbitrarily long day. Using the method I just proposed to rationalize your world's astronomy, you can only deal with the ratio of rotation speed and orbital period. Whether or not this abides by Real World celestial mechanics is IMO irrelevant. I'm proposing the concept is believable as a consistently applicable rule of your world. [Answer] Not a full answer, but points to consider, too long for a comment: On earth every place has 50:50 of light and darkness within the period of one year. Differences of day/night length between summer and winter are caused by the slight pitch of earth' rotation axis. If you are on the northern half of earth, you'll experience summer during the time when the north pole end of the rotation axis looks toward the sun. To have another light/darkness ratio than 50:50 during the year, the rotation axis would have to change. This is likely quite unstable, yet I cannot think of a stable orbit around the sun with a changing rotation axis of the planet. Currently I cannot think of a stable setup that would provide 75% daylight during one year. A special case is our moon that looks at the earth with the same side all the year. Its own rotation fits its orbit around the earth. A planet that looks at the sun the same way like the moon looks at the earth would have daylight throughout the year on one side and everlasting night on the other side. Whatever your planets stable rotation axis would be, a change of the rotation axis would be needed to change its day/night cycles. This, however, would need a really hard impact that likely changes more than the day/night cycle. For example, an asteroid hitting angulary the equator might cause a quicker or slower rotation. This in turn might change the planet's orbit around the sun (though, I am not entirely sure.) An asteroid hitting angulary the north pole might change the rotation axis. [Answer] ## Daily solar eclipses On Earth, there are two cases, when the sun is completely obstructed: nights and solar eclipses. So let's extend the night by eclipses. For most practical reasons, it is pretty much the same thing - it is dark outside, people need torches, vampires can leave their coffins, etc. Let's have a planet with zero inclination (relative to the star) and a moon on a geosynchronous orbit with nonzero inclination (relative to the planet). There is a place on the equator (let's call it the Eclipse Island), where the moon covers the sun twice a day - in the morning and in the evening. [![Surface view on geosynchronous moon with inclination](https://i.stack.imgur.com/koRom.png)](https://i.stack.imgur.com/koRom.png) This results in multiple distinct time periods on the Eclipse Island: 1. Proper night (both the moon and the sun still under the horizon) 2. Moon dawn (the moon rises over the horizon, still eclipsing the sun) 3. Sun dawn (the moon leaves the sun, letting in some of its light) 4. Day (the moon travelling West side by side with the sun) 5. Sun dusk (the moon comes back to the sun disc, obscuring some of its light) 6. Moon night (the moon eclipsed the sun again, but is still over the horizon) 7. Proper night follows again, when the moon falls under the horizon The length of dawns and dusks would depend on the size of the moon and its inclination, so you can fine-tune them to your liking. ## Side effects The same daily eclipses would happen also in some places around the Eclipse island. If you sailed North from there, you would experience both eclipses closer and closer to the noon. Go North enough and you will have three short "days" - one before the first eclipse, one after the second eclipse, and one in between them. There will be a small spot, where these three short days have the same length (followed by a "proper" long night). Go even more North and the two eclipses will be so close to the noon, that they become one. Go Norther and there will be no eclipses at all. Apart of the single area, that experiences the shadow of the moon, there will be no eclipses anywhere else. From most places on the planet, the moon will be always before the sun, or always chasing after it. If you want to bind the day-night cycle with your magic, the Eclipse Island and its surrounding "shadow zones" would definitely feel very magical. Significantly shorter day would also mean the Eclipse Island would be significantly colder, than the rest of the equator. The longer the nights, the greater the temperature difference. Make it big enough and it can lead to some pretty extreme weather. Which may be a good reason, why there is nobody living on the rest of the archipelago. [Answer] A highly eccentric orbit tied to a 3:2 rotation lock (like what Mercury has) could give one very long day and one very long night on alternating orbits, but that's not what you asked for. A 2:1 resonance, on the other hand, with the inhabited island on the light side at apoapsis, could give a fairly short "day" (relative to year length) once a year in which the sun may show some retrograde motion for a time between sunrise and sunset. Depending on the eccentricity of the orbit, there might be other shenanigans (like multiple sunrises and sunsets each "morning" and similar each "evening") as the rotation rate interacts with orbital position (I'd have to set up a simulation, I'm not getting a good visualization). [Answer] The planet's [axial tilt](https://en.m.wikipedia.org/wiki/Axial_tilt) determines the length of day/night cycles along with the latitude of a location. It is possible for a planet to have locations with days/nights lasting 6 consecutive months. Such a planet would have an axial tilt of 90 degrees. An axial tilt of 90 degrees puts the axis in line with the planet's orbital plane. We have a planet close to this in our solar system, with Uranus having an axial tilt of 98 degrees. An explanation for how this works is that the closer to 90 degrees the axial tilt is, the larger the artic and antarctic circles are. With 90 degrees the polar circles extend to the equator giving every location on ethe planet at least a day without sunlight. This also increases the amount of time the poles experience night and day with each pole experiencing 6 months of night and day as mentioned previously. Locations on the equator would have somewhat standard day night lengths. For a 24 hour rotation like Earth, a location on the equator would have a 12 hour day/night on the equinoxes and a 24 hour night on the solstices. It is neat that a planet could have a location with days and nights as long as 6 months, but you want nights as long as 9 months. This would be possible with [axial precession](https://en.m.wikipedia.org/wiki/Axial_precession). Axial precession is when a planet's axis wobbles and changes the amount of the planet's axial tilt. If the planet's axis changes its tilt on a regular period throughout the year a 9 month night and 3 month year would be possible. I haven't looked into the proper amount the tilt would need to change but I'll give an example for how this could work. Let's say the planet fluctuates between 45 degrees tilt and 135 degrees tilt throughout the year and we place our 9 month night location on the north pole. At the winter solstice we will start with a 45 degree tilt. Our location will be in darkness since it is winter for our pole. Now with axial precession our axis will change toward 0 degrees as the spring equinox approaches. But this axial precession not only moves 45 degrees against the orbital plane but also moves the axis 45 degrees with the orbital plane. This tilts the pole away from the sun keeping it in the dark. At the summer solstice the pole will be facing the sun with a 135 degree tilt in the middle of a long sunny period. The autumn equinox would be the same as the spring equinox with the pole facing away from the sun. Now this would not make for a full 9 month night and 3 month day if the planet rotates on a regular period such as 24 hours. For example in the early spring there would be short amounts of daylight that would lengthen as the season went on until day would last longer than 24 hours until there would be short periods of night later in summer. If the planet does not rotate on an axis it would be possible for an exactly 9 month night and 3 month day. In the case of 24 hour rotation around the equator locations would have days and nights of regular lengtha. [Answer] Imperfect [Peaks of Eternal Light](https://en.wikipedia.org/wiki/Peak_of_eternal_light) and [Craters of Eternal Darkness](https://en.wikipedia.org/wiki/Permanently_shadowed_crater) are potentially ways of getting interestingly asymmetrical day/night cycles. Imagine a planet that has no axial spin, so the stars remain fixed in the sky, never rising nor setting, and no axial tilt. At the northern-most point, there is a humongous crater, whose mountaneous rim has a single gigantic chasm in it. As the planet orbits the star, the angle the sun makes with the North Pole changes, and once per year it shines through the gigantic chasm, allowing the inside of the crater to recieve light for a few days. (Or perhaps there is a small axial tilt, and at the height of summer, the sun pokes above the crater's rim) This crater contains water, and the archipelago in question. Quite how the crater walls are so high is suspicious -- I'd suspect some sort of engineering, because the crater walls are going to need to be high enough to be visible from over the horizon (how else do they block the sun?) and that height grows very fast as the angular size of the archipelago grows... Potentially relevant to your interests: a town in a valley in Norway, which is [dark during the middle of the day](https://www.bbc.com/future/article/20170314-the-town-that-built-a-mirror-to-catch-the-sun)... ]
[Question] [ So, I've wound up in jail again (not my fault - I didn't start that fire, honest!) and I need to get out of here before the mayor has a chance to check his safe. Unfortunately, I left my lockpicks in my other pants. Luckily, I happen to be carrying a little vial of metal-be-gone. A few drops on the hinges, and in a matter of minutes it's eaten through the metal, and I can escape. But it gets me wondering... Just what is in that vial? Question: Is there a liquid which can be safely carried (probably in a glass container), and which will rapidly dissolve iron? Preferably something that does not release toxic fumes. If so, what is it, and how could someone (or some group) produce (ideally with a medieval level of technology) or obtain it? [Answer] # Gallium, otherwise: you don't. Ok, you have to assume that whatever you are using this on is made out of Aluminium. But if we can make that assumption the answer is: Gallium. Gallium attacks Aluminium in a quite spectacular fasion. [Here is an example of how to completely destroy a big Aluminium alloy padlock with Gallium](https://www.youtube.com/watch?v=jeghGhVdt9s). [Another example on how to defeat an Aluminium padlock with just a few drops of Gallium](https://www.youtube.com/watch?v=k919f7Qi4es). Gallium is fun because it is a metal that melts in your hand. This means your cute little vial can be disguised as a novelty toy/key ring. But since you need to little of it, you can just hide the vial in your belt, pants waistline or something like that. EDIT: Assuming iron, assuming the Middle Ages and equivalent level of sofistication when it comes to chemistry. Sorry, you simply do not do that. The latter part of [this video](https://www.youtube.com/watch?v=g_M60l2VALI) shows what happens when you put Iron in Hydrocloric Acid. In short: not a lot. Iron is simply too noble a metal to be easily attacked by acids. Sure, Aqua Regia was described in the 1300's... but 1) it is not fast acting 2) you need quite a bit of it and you need to keep it in contact with the iron for a long time; you cannot just pour some on and 3) that a common criminal that ends up in jail a lot would have access to this stuff is just not plausible. [Answer] For fun I would go with Aqua Regia, or Royals Water/Kings Water based on the Wikipedia article. It can dissolve almost all metals including gold, silver and platinum. As for how to get it and whether its safe in a glass container? I have no idea. But its fun to know you have a vial of liquid that is capable of chewing through almost any metal. [Answer] # If you can’t dissolve ‘em, freeze ‘em. Your vial consists of two powders, Ammonium thiocyanate and barium hydroxide octahydrate, separated by a thin membrane. When combined, these substances become quite cold, as you can see in many scientific demonstrations (instant ice packs work the same way). Once the hinges are cooled to around -13F, you shatter them with a rock. # If you can’t freeze ‘em, melt ‘em. In your vial is aluminum powder and a wee bit of magnesium powder, and you are fortunate in that the hinges are very rusty. You also happen to be wearing spectacles that your jailer was kind enough to leave you. You pack the hinges with the aluminum powder, use your spectacles as a magnifying glass, and light the whole thing up. The thermite reaction you get should slag iron. [Answer] If you renounce to not releasing toxic fumes, you can go with [hydrochloric acid](https://sciencing.com/dissolve-iron-8374475.html). (Actually, hydrogen is not toxic but "just" hazardous). > > Iron doesn't dissolve readily in water, although it will definitely rust more rapidly (as you've probably noticed from experience). Hydrochloric acid, however, can dissolve iron, and a more concentrated solution will dissolve it more rapidly. [...] First of all, it releases highly flammable hydrogen gas, so it should be performed under a fume hood. Moreover, hydrochloric acid is also a hazardous chemical if misused; it's especially important to avoid spilling it on skin or eyes. With these cautions in mind, you can dissolve iron using hydrochloric acid. > > > If you manage to avoid any sparks during the process, you will be free and alive. Else there will be nice fireworks involving you, and you will be, again, free but very likely dead. Production of HCl with medieval technology should be possible, [since](https://en.wikipedia.org/wiki/Hydrochloric_acid) > > Hydrochloric acid has been an important and frequently used chemical from early history and was discovered by the alchemist Jabir ibn Hayyan around the year 800 AD. Free hydrochloric acid was first formally described in the 16th century by Libavius, who prepared it by heating salt in clay crucibles. > > > [Answer] A solution of acetic acid, salt, and oil. You're not actually "dissolving the metal", you're de-rusting and lubricating the hinge pins so that you can pull them out effortlessly - as a bonus, you can then slot the pins back to hold the hinges together again when you're out of the cell, and leave everyone bamboozled as to how you made your escape. [Answer] ## Fluoroantimonic acid (H2FSbF6) If you want something very strong, which can dissolve also almost anything, I suggest you to transport a small vial of Fluoroantimonic acid (H2FSbF6). It may be currently the strongest acid that we know as it can dissolve metals but also glass! The reaction to produce it involves hydrofluoric acid and an Antimony derivative. Antimony has been firstly described in [1540](https://en.wikipedia.org/wiki/Antimony) which matches with your medieval setting and it was even used before that in ancient Egypt. SbF5 + 2 HF → SbF6- + H2F+ The only problem is that you have to transport it in a vial made of Polytetrafluoroethylene (PTFE) as it will dissolve any other recipient! PTFE is more wildly known as Teflon and has been discovered in 1938. But it has been synthetized by mistake and with a really simple process... So simple that you could imagine a very advanced alchemist sect which would discovered it during the middle age: Just store some compressed Tetrafluoroethylene (TFE) in a steel bottle in some ice for a night and there you go, Teflon in the morning (simplified version of course). Again, TFE is not a natural molecule so you have to imagine your alchemist sect to be way ahead of his time... By the way it surely release a ton of toxic fumes as Antimony is known to be very toxic ! ]
[Question] [ With Mars' color coming from the iron oxide, is it possible for such a small body without an atmosphere to support that color? [Answer] The redness of Mars' surface comes from the large quantities of iron in its crust. Other terrestrial planets in the Solar System also contain iron, but not at their surfaces. Mars in particular has several things going for it that allowed it to keep much of that iron in the crust: * [Low surface gravity](https://www.space.com/16999-mars-red-planet.html) * [Low temperatures in the initially molten crust](https://www.nature.com/news/2004/040503/full/news040503-6.html) These both prevented differentiation - essentially, the vertical reshuffling of different minerals due to differences in weight - and the melting of iron. Both would have caused the iron to drop into the planet's mantle and core. However, the environment wasn't conducive to this restructuring, and so the iron was able to stay in the crust. Your moon - presumably with a low mass - would have the same optimal physical properties, although, as I'll talk about later, the lack of an atmosphere is problematic. Chemically, [Mars is red](https://en.wikipedia.org/wiki/Mars_surface_color) because iron is present in the dust layer coating much of the surface. A hematite (Fe2O3) is likely the main culprit for the color, with much of the rest of the iron being stored in a black magnetite (Fe3O4). Now, one way to generate this involves oxygen gas (O2). However, oxygen was never present on Mars in large quantities - and it clearly can't be on a body with no atmosphere! It's been suggested that a reaction of iron (Fe2+ or Fe) with liquid water could indirectly form the proper minerals. Dissolved carbon dioxide and sulfur dioxide (CO2 and SO2) could act to speed the reactions up. Hydrogen peroxide (H2O2) leads to yet another reaction pathway. However, these two avenues both involve either an atmosphere or liquid water, which bother me for your specific setup. Now, [it's been theorized](https://web.archive.org/web/20090925011644/http://news.yahoo.com/s/space/20090921/sc_space/howmarsturnedredsurprisingnewtheory) that specific erosional processes could turn magnetite into the right kind of hematite. The crushing and colliding of magnetite with other materials provides a possibility, and doesn't necessarily require erosion by fluids (gases or liquids). It does, however, require a source for the magnetite in the first place. All of that said, it's unlikely for hematite to easily form on a body with no atmosphere (and thus likely no liquid water). It's possible for it to form slowly, and on long geologic timescales, so I won't rule it out entirely. It would just be difficult, with a normal concentration of iron. It's possible that an iron-rich impactor - such as another protoplanet - could have collided with your moon early in its history, dumping iron all over the surface. The problem here is that collisions between celestial bodies tend to turn crusts molten - and as I said before, that's not good for keeping iron in the crust! It would cause extreme restructuring, and that's a problem. Could it happen? Maybe. Am I optimistic? Not terribly. --- ## Inspiration from our Solar System Let's look to our own planetary system for some inspiration. Mercury has a large amount of iron in its core - and in fact, Mercury's core is more than half of the planet, by volume. Its crust and mantle are comparatively thin. One common explanation for this is that [an impactor stripped away most of the outer layers](https://astronomy.stackexchange.com/a/412/2153), leaving behind a planet that was, by mass, a greater percentage iron. Now, the iron in the planet was already in the core, and I would expect that the molten surface caused by such an impact would have allowed any additional iron to travel to the core. Given that your moon is so small, I suspect that a similar impact, rather than a relatively grazing one, like [the one Earth suffered](https://en.wikipedia.org/wiki/Giant_impact_hypothesis), would have led to the same sort of process. Surface conditions would not have been good for iron to stay there, and it's certain that no iron would have been dredged up from the depths of the planet. Now, a possible loophole is to have an event - or rather a series of events - like the [Late Heavy Bombardment](https://en.wikipedia.org/wiki/Late_Heavy_Bombardment), which may have occurred about 4 billion years ago in the Solar System. A substantial number of asteroids and other bodies collided with the terrestrial planets (a similar event may be occurring in the exoplanetary system around [Eta Corvi](https://en.wikipedia.org/wiki/Eta_Corvi). A prominent theory for the cause of the LHB is the change in orbits of the giant planets in the outer section of the Solar System, as per the [Nice model](https://en.wikipedia.org/wiki/Nice_model) and variants thereof (e.g. the Nice II model). If an unusually large number of [iron-rich meteorites](https://en.wikipedia.org/wiki/Iron_meteorite) struck your moon during an analogous event, you could have large-scale iron deposition without a single cataclysmic impact. [Answer] You want a red moon, and you note Mars is red, but you did not mandate that the red moon must be red for the same reason as Mars. Paint it red with tholins! <http://www.planetary.org/blogs/guest-blogs/2015/0722-what-in-the-worlds-are-tholins.html> Consider Titan. It is a reddish orange moon. <https://www.nasa.gov/mission_pages/cassini/multimedia/pia06081.html> [![titan](https://i.stack.imgur.com/IKEFZ.jpg)](https://i.stack.imgur.com/IKEFZ.jpg) Titan is a natty orange due to tholins in its atmosphere. <http://www.planetary.org/blogs/guest-blogs/2015/0722-what-in-the-worlds-are-tholins.html> [![tholins](https://i.stack.imgur.com/uPYWC.jpg)](https://i.stack.imgur.com/uPYWC.jpg) Europa has big red scratches on it that are probably red for the same reason (full of red tholins). And it turns out large swaths of Pluto (which is smaller than Titan or Luna) are also red from tholins. [![pluto true color](https://i.stack.imgur.com/6c3mh.jpg)](https://i.stack.imgur.com/6c3mh.jpg) <https://www.nasa.gov/image-feature/global-mosaic-of-pluto-in-true-color> <https://www.universetoday.com/13866/color-of-pluto/> > > The surface also has many dark, reddish patches due to the presence of > tholins, which are created by charged particles from the Sun > interacting with mixtures of methane and nitrogen > > > [Answer] ## Cinnabar Or [Mercury-Sulfur](https://en.wikipedia.org/wiki/Cinnabar) (HgS). The creation of cinnabar requires no atmosphere, just igneous rocks with some water. If the moon had a lively volcanic past and plenty of mercury and sulfur then it would be easy to get large patches of the lovely red powder you see below. The question implies but does not require iron oxide. [![Red Cinnabar](https://i.stack.imgur.com/3Zl7M.jpg)](https://i.stack.imgur.com/3Zl7M.jpg) [Answer] So your question is basically, can an atmospheres moon have oxidized iron? Short answer is yes. Long answer depends on what the moon is made out of or how it formed. During the formation of our solar system there was a lot of gas floating around in the protostellar nebula. Could oxidation happen then? Why not. [Answer] At temperatures over 200°C, sulphurs turns a blood red colour. Sulphur is the tenth most abundant element in the universe (by mass), and the fifth on Earth. Having a moon whose surface (or even entirety) is sulphur is not far fetched (Jupiter’s moon Io is covered with sulphur compounds). Now the heat. Luna has a daytime surface temperature of about 100°C. To get a further 100°C, you could add: * heating due to radioactivity at the moon’s core * a brighter/hotter sun * friction from tidal forces due to low orbit and/or other moons [Answer] Is it possible? Yes. Here is a scenario. An asteroid collides with mars and shaves off enough of the surface layer (red) to make an object roughly the size of the moon. Now put rockets on it and move it into orbit around earth, or have it naturally come into orbit around something like the planet Earth. Now you have a red moon. Over time it should even become sphere like. Done. ``` You only asked if it was possible. ``` ]
[Question] [ Researchers are scratching their heads, and Portland Water Bureau is furious. In Portland, Oregon, a reservoir in one of the City parks has begun spilling out a river of naturally occurring beer/ale. How can this happen? I'd like to avoid magic or human intervention in favor of a series of coincidences that created this natural craft. While it can get contaminated / dirty as it spills out, it must be drinkable and be a lot. It can occur in a reservoir, in the geology, in pipes, or in a water tower. A little bit of hand-waving is acceptable, if necessary. Everything is present-day, Pacific Northwest, any season. [Answer] Some biotech firm is experimenting with a beer-producing algae. Somehow it got loose in the reservoir. It's been growing there, the weather changed to the point it released its built-up crop of beer. [Answer] I would guess for the beer to even be recognizable as such, it is going to have to be someone's idea of a planned practical joke. About the best I can see for something like this to happen would likely be something the size of a water tower. it's small enough to actually be possible. It still is unlikely but it might be done during one of the scheduled maintenance runs. Many large cities with multiple water towers generally empty one out for maintenance fairly regularly. So who ever is in charge of that schedule would have to be in on it or tricked into 'serious repairs' needing to be done. It would also need at least several accomplices to get the beer into the tower, whether it is bring all the ingredients up and mixing the mash in the tower and letting it go for 2 weeks while 'repairs' are going on or just buying semi loads of the beverage and pumping it into the tower. Pure accident? unlikely, most likely chance would be a grain tower or two being flooded and a small miracle of the right stuff being together for the right amount of time with enough heat. [Answer] # NOTES You will need to change the numbers and timing to fit. Also, I'm not too happy with how the grains get there. # 100 000 000 BC Mount WannaMakaLotaBrew started off life as a crack in the Earth's crust with a silver spoon (er...ore) in it's mouth. Being born near the beach (and creating the beach) this allowed layers sand to be mixed in with layers of silver ore (antibiotic) As time went on, plant/animal life started to appear. Every 100 years or so, Mount WannaMakaLotaBrew turned them all living matter into a nice layer of charcoal (other filtering) # 1 000 000 BC Mount WannaMakaLotaBrew decided to get some rest but had a lot of magma left to get rid of first. For years, Mount WannaMakaLotaBrew gave the lava in a slow steady fasion. In the process, lava tubes formed. When all was done, Mount WannaMakaLotaBrew rolled over causing the lava tubes to now be at steep angles. # 5 000 BC Princess Buzzbuzz Bzzz (a wild queen honey bee) decided to leave her hive and start her own hive. After days of searching, she ran across a nice little cave system. It was long, dark, and stayed warm in the winter. She had found one of the lava tubes of Mount WannMakaLotaBrew. She picked a spot near the location where snow melt was starting to be collected. This collection would grow into underground lake, and provided the hive of Princess Buzzbuzz Bzzz a source of clean fresh water and cool air during the summer, and the heat from the lava tube's bottom provided the warmth through the winter. Her hive would thrive. As the years go on, Mount WannaMakaLotaBrew tossed and turned. In the process, parts of the honey collected by the hive of Princess Buzzbuzz Bzzz broke off and fell down the lava tube. After eons, the bottom of the lava tube had collected a ton of honey. Honey that is as ancient as that found in Egyptian tombs and just as well preserved. # 100 AD A tribe of Native Americans found a cave system with a bottomless pit. To appease the god of Mount WannaMakaLotaBrew, they would sacrifice a 100 pounds (adjust numbers to make sense) of grain down this bottomless pit. Every now and then, Mount WannMakaLotaBrew required more sacrifice and showed his dissatisfaction with an earthquake. # 1800 AD A former brewmaster from the Yuengling family wanted to start his own brewing company out west. While on the Oragon Trail, he spotted some Native Americans near Mount WannaMakaLotaBrew. In preparation for an ambush, he hid a barrel of brewers yeast in a cave close to a pit. (the same bottomless pit) He died of dysentery shortly after. # Near Future Due to global warming, the top of Mount WannaMakaLotaBrew became the perfect spot for growing hops. The Portland Brewing company had a high demand for Oregon hops. A lot of farmer land appeared, adding many silos of hops to the top of Mount WanaMakaLotaBrew. # Near Future + 1 day Mount WannaMakaLotaBrew was beginning to wake up. An earthquake caused a fissure near the top. This fissure swallowed some of the silos of hops down and their contents to the bottomless pit (lava tube). Additionally, the abandoned barrel of brewer's yeast from 1800's fell into the pit. The underground lake drained into the pit also. Mount WannaMakaLotaBrew had heated up the bottom of this particular lava tube for the correct temperature for brewing beer. (Optionally) Mount WannMakaLotaBrew heated up the lava tube that the hops fell down high enough to slightly toast them. # Near Future + 3 months Winter at the top of Mount WannaMakaLotaBrew has come and gone. The snowmelt found a new route. This new route leads the water to the bottomless pit that contains the beer mash. This allowed the millions of gallons of (now beer) liquid to reach a particular point where it can drain to a lower elevation (like a toilet flush) As it drains, it passes through sand (filter), silver ore (antibiotic), charcoal (poison filter), and more sand (extra filtering) making the brew safe to drink as it gushes out into a nearby reservoir. [Answer] Well, I don't have a permanent solution, as in, the beer flows forever, but I can think of a way where it happens for a while: Ever hear of the [Great Boston Molasses Flood of 1919](https://en.wikipedia.org/wiki/Great_Molasses_Flood)? A giant tank holding molasses burst, and released 2.3 millions gallons of molasses in a 25 foot high tidal wave moving 35 mph that swept through Boston. It would be hilarious except 21 people died. Anyway, to make tasty alcoholic beverages you need two things: sugars, and yeasts. You could recreate the Great Molasses Flood (modern update: Great Corn Syrup Flood) from a giant holding tank that's on a hill above the water reservoir. All of it runs down the hill into the water, where it mixes. From there, natural airborne yeasts (note: there are some superb Belgian beers made this way. Not in a lake, though. In open tanks) settle in for their favorite feast in your syrupy water, and viola, beer/mead/whatev flows from the taps. Possibly you could drag this out by making it a unknown/covered up leak, but I kind of doubt you could get the sugar concentrations high enough without it being obvious where it comes from. [Answer] I know this. Sourdough was originally discovered when a lot of flour was left out during a rainstorm near the nile; producing a natural starter. As that starter is a yeast, given that there is some reasonably large presence of grain in the water, and enough time for it to ferment, you could hypothetically create a beer-like substance that way. It's also quite common at watering holes, on the African savannah, for fallen fruit to ferment on its own and literally make the animals drunk as skunks. Perhaps a sufficient quantity of one moistened grain or another could strongly ferment up spring, much like the fruit of the watering hole, then form effective beer on its way out. [Answer] Alright here's a scenario -Earlier this season Portland experienced an extreme bumper crop of barley and wheat. -located near the city park is an old but still functioning grain processing silo: Tim's Grains -During the bumper crop Tim's Grains wasn't able to compete with the lower prices of competing newer plants and was stuck with an overflow of grains now beginning to go bad in the silo. In order to save what they could of their product they decided to dump a portion of their more gone grains into the nearest reservoir in the dead of night by stroke of luck it was yeast that was corrupting their grains. [Answer] If you want coincidences... Well how about "the great landslide". The cliff overseeing the Sugar lake collapsed during "the great storm". Sugar Lake got its name because of the large amounts of sugar cane growing there. farmer Bill has his grain farm next to the lake. The landslide mixed the grain and sugarcane along with just the right amount of water into a little pocket of ground water where the drinking water is taken from. After a while this fermentation process creates beer, and it gets into the water supply. ]
[Question] [ An [artesian basin](https://en.wikipedia.org/wiki/Artesian_well) is an aquifer in which water within permeable rock is kept under pressure between 2 layers of impermeable rock. I don't know if any artesian basin exists like this in real life, but i haven't heard of any. However, given that an artesian basin is under pressure between 2 layers of impermeable rock, would it be possible for it to pass underneath a sea without becoming salty due to the impermeable rock? The sea it would go under is about 150-265km wide. Both sides have mountains on them & the area underneath one of those mountains is a subduction plate boundary. [Answer] In support of what you're looking for... > > On a clear September day in 2015, after 10 years of working to get funding, my colleague Kerry Key and I stepped aboard the R/V Langseth, a research ship docked at the Woods Hole Oceanographic Institution in Massachusetts. We were about to lead a 10-day expedition to map a deposit of fresh water, size unknown, hidden 100 meters (about 330 feet) under the rocky seafloor. ([Source](https://www.scientificamerican.com/article/found-giant-freshwater-deposits-hiding-under-the-sea/)) > > > Freshwater aquifers can and do exist beneath the sea floor. And frankly, the more shallow the sea, the easier it would be to rationalize the aquifer. > > A continent does not stop at its shoreline; it extends well offshore as a rocky underwater shelf. The shelf ends at a steep slope that transitions sharply to deep oceanic seafloor. The rock and sediments that make up the world's continental shelves are not dry. Some rocks crack, allowing seawater to penetrate. And most shelves are covered by layers of sedimentary rock, which are like hard sponges with small, interconnected, water-filled pores. > > > Sediments at or just below the seafloor are typically 40 to 50 percent porous. The weight of the ocean above pushes water down into the sediment as far as it can go. Geoscientists still debate the maximum depth, but it can be at least several kilometers, although the seepage decreases rapidly with depth as the increased pressure closes up cracks and pore spaces. The rock's permeability—the ease with which water can flow through it—depends on how extensively its various pores are interconnected. > > > Because the shelf is a continuation of the continent, models of groundwater flow in land along the northeastern U.S. coast suggest there could be substantial amounts of fresh water hidden within the rocks and sediments below the continental slope's seafloor. But there are competing hypotheses about how such water might get there—and remain there. (Ibid.) > > > @L.Dutch's answer, which I upvoted, makes a point, but it might not be the crisis he's suggesting. It's easy to rationalize an undersea fresh water aquifer — but only when the ground beneath the aquifer isn't so messed up that it can't reasonably retain the water. Consider this image from the quoted article: [![enter image description here](https://i.stack.imgur.com/dBTXr.jpg)](https://i.stack.imgur.com/dBTXr.jpg) Credit: Julia Ditto; Source: “Origin and Extent of Fresh Paleowaters on the Atlantic Continental Shelf, USA,” by Denis Cohen et al., in Ground Water, Vol. 48; January-February, 2010 (reference). Image sourced from Rob L. Evans, "[Found: Giant Freshwater Deposits Hiding under the Sea](https://www.scientificamerican.com/article/found-giant-freshwater-deposits-hiding-under-the-sea/)" (July 1, 2023). In all those examples you'll see that the flow of rainwater from the land is contiguous. If you break that up with a fault line, you should expect the aquifer to end at the fault. Worse, the fault line represents a way for salt water to enter the undersea strata, meaning the aquifer will push less into the undersea region than it might otherwise have done. I note that you describe the fault line (the subduction layer) under the mountains... not under the ocean. From a practical perspective, that means the water is running down the mountain and being absorbed into the undersea strata. Since the fault line is behind the aquifer, you don't have a problem. What you won't have is an aquifer on the other side of the mountains unless you allow sufficient rainfall on that side (in a continental context, the mountains could believably cause a continent-side rain shadow). And a word about undersea artesian wells... This is more believable than you might think, but not because of pressure. Again, from the linked article: > > Records of fresh water being found offshore go as far back as the 1800s. Fishers off Florida have occasionally reported “boils” of water on the ocean's surface, which they assume leaked upward from below. In some cases, they sampled the water and it did not taste salty; fresh water is less dense than seawater, so it rises. (Ibid.) > > > In other words, you don't need pressure. You only need a leak and enough volume of fresh water that the press of salt water doesn't inundate the leak, causing that region of the aquifer to turn salty. Permeable, impermeable, kinda doesn't matter. By definition an aquifer forms because the water stops going down, not because it can't go up. In other words again, it means you can use the idea of impregnable rock as a story concept, but it's unnecessary for the science to work. All you really need is an easier path for the freshwater to enter the aquifer from land than for the saltwater to enter in the sea. [Answer] There is one point which I see as a big no no with respect to what you describe: > > the area underneath one of those mountains is a subduction plate boundary. > > > This is a [simplified tectonic](https://www.researchgate.net/figure/A-Simplifi-ed-tectonic-map-of-Italy-and-surrounding-regions-The-Gargano-fault-system_fig1_249517888) map of the Adriatic sea, which resembles the sea you describe: [![enter image description here](https://i.stack.imgur.com/3PNvN.png)](https://i.stack.imgur.com/3PNvN.png) The presence of a subduction plate boundary will lead to faults which will break the 2 layers of impermeable rocks needed to maintain the basin separated from the salty water above it. With those faults fresh water in the basin will get mixed with salty water from the sea. [Answer] In the seventies, the London-Brabant massif was thought to have an aquifer that spanned the English Channel / La Manche in this way. It probably doesn't. It is possible, but for the reasons cited in several other answers, it is unlikely. Seawater will enter, and fresh water will leave if there are any faults. The [Great Artesian Basin](https://en.wikipedia.org/wiki/Great_Artesian_Basin) in Australia is big enough to span the gap you require. If the basin was filled on the surface with salt water, this would be doing what you want. However, if you want an ocean that divides two land masses, then we need a 'U'-shaped or saddle-shaped deformation, or some fault-based graben that managed to seal itself, both at the faults and at either end. The 'neck' of the great Artesian Basin might work this way, but the subduction zone you mention makes a concave warp at the sea-bed rather unlikely. If the impermeable rock was flat, but sloped, a bit like the aquifer found off the eastern US recently, and you drilled a deep well on the subduction zone side, you might get the artesian well you wanted. This is much more likely but the well would be very deep. For a 200 km span, and a 1% slope, you would have to drill down 2 km. You might be able to tweak the parameters in your story to make this work. [Answer] There is a deep fresh water artesian well on Spitbank fort just offshore from Portsmouth England. And probably on the other three sea forts as well. <https://en.wikipedia.org/wiki/Spitbank_Fort> [Answer] It's definitely possible, there are several areas off my island where you can dive down and drink fresh water coming up from the seabed. We did it as children for fun, you just cover your mouth with a cloth to stop from sucking sand and it was fresh water. ]

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