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[Question] [ [Atlantropa](https://en.wikipedia.org/wiki/Atlantropa), Herman Sörgel's proposal to turn vast swathes of the Mediterranean Sea into livable dry land by installing five hydroelectric dams (the main one across the Strait of Gibraltar), is an awful idea for a great MANY reasons. Ignoring all the pesky social and political problems with the concept, what's the worst possible *environmental* outcome of a successful Atlantropa project? Many articles mention that the project would raise the sea level around the world with understandably disastrous consequences, but *Popular Mechanics* implies an even worse scenario: > > The reduced weight of water over the volcanic Mediterranean sea floor would probably lead to violent eruptions and earthquakes. (*Popular Mechanics* March 1977, ["Power from the sea: Fact or Fancy" p 193](https://books.google.com/books?id=B-QDAAAAMBAJ&lpg=PA192&ots=BgWwvU6PV6&dq=popular%20mechanics%20atlantropa&pg=PA193#v=onepage&q&f=false)) > > > I can easily imagine such geologic upheaval causing tsunamis and worldwide atmospheric effects, not unlike the [1883 eruption of Krakatoa](https://en.wikipedia.org/wiki/1883_eruption_of_Krakatoa). [Others have claimed](https://www.youtube.com/watch?v=TEdsQmjLMKs) it would cause a European ice age. I expect there's a myriad other factors I haven't run into yet. **What's the worst plausible outcome of a successful attempt to create Atlantropa, with regard to global physical/environmental disasters (not social or political), both short-term and over the next decades?** If it matters, assume it's implemented in the late 1940s without any environmental impact oversight whatsoever. [Answer] The Atlantropa project envisioned damming the Gibraltar in order to lower the Med by 200 meters. Anything more than 20 meters would transform the Bosphorus into a gigantic waterfall, cutting off (in clockwise order) Bulgaria, Romania, Russia, and Georgia from the Mediterranean. The immediate and devastating effect would be a war between the proponents of the scheme and Russia. *The scheme would be very short lived.* Geologically speaking, not much will happen. The Med is 1500 meters deep on the average, wiping off 200 of those meters is not really that important. The water volume of the Med is tiny compared to the ocean, so the increase in sea levels elsewhere will be modest. [Answer] This would be an incredibly BAD idea. The environmental and economic changes would be incredibly negative. We can actually see the results of a much smaller sea drying up when we take a look at what happened to the [Aral Sea](https://en.wikipedia.org/wiki/Aral_Sea) during the 70s, 80s & 90s Draining the Mediterranean - far from simply creating vast new areas of land for people to colonize - would actually create massive new deserts. In addition it would devastate coastal economies right around the entire sea. The entire coastline would shift by dozens if not hundreds of miles. It would also have the effect in current geopolitical circumstances of making it far easier for refugees to get to Europe. [Answer] On top of what other answers are suggesting, I am sure that removing 200 meters of water over the entire surface of the Mediterranean sea (2.51 million square meter, counting to 500 million cubic meter, roughly 500\*10^9 kg) will sensibly alter the momentum of inertia of the planet and will consequently affect its rotation, slightly changing the duration of the day and the rotation axis. ]
[Question] [ In a [story of mine](https://worldbuilding.stackexchange.com/questions/38428/how-long-would-it-take-us-to-detect-a-deimos-like-object-moving-towards-sol-from) mankind has established a permanent base on the earthward-side of the Moon complete with a [beanstalk dangling into Earth-Luna-L1](https://en.wikipedia.org/wiki/Lunar_space_elevator) for easy transport of material off Luna. Getting off earth is simply a task of getting into [LEO](https://en.wikipedia.org/wiki/Low_Earth_orbit) at which point craft from Luna take over crew and materials. Returning things to earth is a simple task of slowing containers/ships down sufficiently so they reenter orbit. --- After finishing the moon-side constructions for the beanstalk (digging and building foundations, etc...), the construction equipment and teams haven been relocated to start building the Lunar-Radiotelescope (LunaR) similar to [the ARECIBO](https://en.wikipedia.org/wiki/Arecibo_Observatory) or [the FAST](https://en.wikipedia.org/wiki/Five_hundred_meter_Aperture_Spherical_Telescope). It can be assumed that *active* preparations and planning for this massive *Lunar-Infrastructure-Project* (*LIP* for short) have been going on for as far back as ~2022. --- Considering the limiting factor for this operation being the materials and things that will have to be built on earth and moved up to moon: **What would be the best location to build such a telescope on moon?** *Bonus:* How long would it approximately take? > > The question is asking for a location, not just a vague idea. E.g. the name of a [lunar crater](https://en.wikipedia.org/wiki/Lunar_craters) or [lunar coordinates](https://en.wikipedia.org/wiki/Selenographic_coordinates) > > > [Answer] Daedalus Crater has been suggested for this purpose. [![enter image description here](https://i.stack.imgur.com/arZYM.jpg)](https://i.stack.imgur.com/arZYM.jpg) Located at 5.9°S 179.4°E <https://en.wikipedia.org/wiki/Daedalus_(crater)> ## Why is it a good choice? **Location** It is near the middle of the far side, furthest from Earth's radio emissions with the bulk of the Moon between it and any terrestrial radio sources. This is the primary benefit of placing a radio telescope on the Moon, the bulk of the Moon's mass would block the majority of Earth's radio output. Placing it just over the horizon or at one of the lunar poles would not block all of the radio waves. The distance the radiation penetrates is based on the [Attenuation length](https://en.wikipedia.org/wiki/Attenuation_length) and the wavelength of the radiation. This location maximizes the mass of the moon between Earth, offering the most shielding possible. As an example low frequency AM Radio has a wave length in the 10 kilometer range, so if you want to block 99% of the radiation (for a telescope you would want to block much more) you would need about 5× the wavelength of material or >50 km of material. There are also longer wave frequencies in use on Earth, so more distance of material is better. **Size and Shape** In terms of size it is one of the larger craters on the moon. It is ~93 km in diameter with some central mountains for focal point instrumentation. for comparison Arecibo is only 305 meters, so Daedalus would be about 300× larger. It is also fairly circular and symmetrical (useful for shaping into a spherical reflector) for craters much larger than this the craters stop having the bowl shape needed for a reflector due to the curvature of the surface. Bigger is usually better for a telescope as it allows it to capture and focus from a larger area giving it better resolution. Another feature it has is a central mountain allowing the receiving instruments to be placed without the need for large support towers and very long wire supports or other large support structures, this helps a lot in terms of lowering the construction difficulty. Shaping it into a better reflector shape would definitely be a major project, somewhat comparable to large open pit mining done on Earth. The [largest man made excavation on Earth](https://en.wikipedia.org/wiki/Bingham_Canyon_Mine) is only 4 km wide and 1 km deep and has been in production for more than 100 years, so this would be bigger but should only require minimal material removal given the existing crater shape (It's hard to say minimal with a straight face for an amount most likely measured in km³). ## Estimates Likely unifying the central mountain system and siting the instruments would be done first, with sculpting the crater walls into a better reflector shape continuing to improve the telescopes resolution as the project progresses. For improved performance they would also likely want to line the crater with an improved reflector material (Arecibo started with a wire mesh and later upgraded to Aluminum panels). Making any accurate time estimate for a project this big is going to be impossible without knowing the capabilities of the Lunar construction apparatus, but it could easily be a decades long project just to construct the first instruments with refinements continuing for the foreseeable future, with each upgrade improving the range and resolution of the telescope. [Answer] I imagine it must be built where the Earth is not visible, to eliminate the bulk of manmade noise and interference. Just over the horizon might be sufficient. But if the moon proves to have an ionized atmosphere then more distance will be required. I expect the half of Luna not visible from Earth will continue to be referred to as the 'dark side' even though it is as illuminated as the visible face. In this context 'dark' refers to the blanking of direct radio communication from Earth. A high speed railroad should be constructed from the base of the stalk to the LunaR site. This will greatly ease construction, especially in the early stages when the construction site does not yet contribute to its own sustainability and all consumables have to be trucked in. Unfortunately the railroad will attract other research groups who want to work on the dark side, so a wise administration will build spur lines to keep their settlements away from the LunaR. One thing to note is that a large *ARECIBO* style antenna on Earth sweeps the sky at about 360 deg. per day, while a similar construction on Luna will be approx. 28 times slower. OTOH given the technology that built the beanstalk coupled with Luna's famous low gravity, you can expect to build an array of truly enormous steerable dishes. [Answer] If you put it at one of the poles, you can erect a solar array to keep it powered all the time. If you "find" a sufficiently-sized crater at one of the poles to put it in, or a ridge to hide it behind, you can curtain off most of the radio interference from Earth. As for time to construct, it's kind of up to you. What's the level of automated construction in your world? Can you send automated or tele-operated bulldozers to carve out the footing trenches? Can waldoes construct the main dish body for you, operating 24x7 until its done? Also, large construction projects like this take a lot of lead time for planning, design, resource deployment, etc., so consider writing hooks into your story a couple of years ahead of groundbreaking that describes project initiation, site selection, etc. [Answer] How about [De Gerlache crater](https://en.wikipedia.org/wiki/De_Gerlache_(crater))? it's in perpetual darkness so can't be observed from Earth, is near the south pole so can have solar power arrays nearby. ]
[Question] [ Solar wind density is very low even at Venus it is only 10 or so H+ ions per cm$^3$ but it is moving at a brisk clip of 400 km/s for the slow wind and 750 or so for the fast wind. So (feel free to check my math here) if one collected all the H+ ions passing thru a 1 cm$^2$ square in a second you would collect 400 000 000 H+ a second. With a 388 km$^2$ set of collectors you would get a mole a second or about a liter a minute. Build one of the dealy-bobs in venereal orbit. Use the mole a sec of hot H+ is reacted with the copious $CO\_2$ available in the neighborhood in some kinda high energy Sabatier reaction $CO\_2 + 4 H\_2 → CH\_4 + 2 H\_2O + energy$ producing about 9ml of water and 11.2 liters of methane a second. That's 778 liters of water a day enough for 259 people (who like to pee off the side of balloons far more with a conservation and recycling effort.) Of course, the collectors could be scaled up. So here are the issues. 1) What does the collection tech look like? I assume it creates negatively charged fields to funnel the H+ ions into the atmosphere. 2) What amount of energy is needed to run it? Would Photovoltaic be enough at that range? Assuming highly efficient panels. Could the high energies of the particles themselves be used as an energy source? [Answer] I would imagine that you would have several different systems in place for this to work' In space, you would have superconducting rings to act as funnels or traps for the hydrogen ions. This is a variation of the Magsail idea (using a superconducting ring to interact with the solar wind to generate thrust), the issue here is you need to negate the thrust, or at least moderated so the rings stay on station. Once the hydrogen is funnelled through the ring(s), it will need to be slowed down, cooled and compressed. Hot ions of hydrogen will be difficult to work with, so you will need a cryogenic cooling plant in the system to bring the hydrogen into liquid form so it can be easily transported to Venus. (Blowing the hydrogen ions into the Venerian atmosphere will not initiate reactions, and the heat of Venus' atmosphere will ensure the hydrogen rapidly escapes back into space). Tankers of liquid hydrogen can then be shipped to Venus (perhaps using the superconducting rings as magsails again) and dropped from orbit. Since the tanks can enter at an arbitrary speed and into an atmosphere with pressure of up to 90 bar, the reentry can be rather gentle and the hydrogen collected at the reformulating plant. Based on your question the plant is floating in the atmosphere and the reaction will take place in "mid air" The Methane is not going to be very useful without oxygen to react with, so it can either be stored or used as a reactant to make various forms of carbon building materials like diamond, graphene or carbon nanotubes, and the hydrogen recycled into the reactor. If you do have either oxygen or a nuclear thermal rocket, the methane can also be used as rocket fuel or reaction mass as well. As for the question of "how much energy", the answer is "it depends". Solar energy is very abundant (2643 w/M^2 in the orbit of Venus), so the amount of energy you will need depends on how large you want to scale the system, the conversion efficiency of the machinery and (vey importantly) how efficient the heat rejection system is. You will have a lot of waste heat, but the environment in the atmosphere of Venus will be very difficult for heat exchangers to reject waste heat into (the atmosphere near the surface is hot enough to melt lead). There are a lot of different assumptions you will need to determine to calculate you energy budget, but being able to operate on a large scale in space and go to Venus suggests that getting that amount of energy will be fairly easy. [Answer] The 'dealy-bob' needs to be an expandable sphere (like the toys yogis use to teach proper breathing) with a skin of foil with a rotating molten iron doughnut shaped core in the middle. The rotation of the iron will create a magnetic field just like on earth and capture the solar wind plasma through the poles just like auroras and direct it from opposing directions to the center of the core where it will collide, releasing energy to the metal and turning into gas. The whole sphere shall also rotate, so the gas migrates to the equator, cooling and liquefying in a ring shape in the process. The dimensions should be calculated such as the iron core radiates out as much energy out in space in a unit of time as energy is released to it from the cooling solar plasma. Once the liquid hydrogen reaches a certain volume the sphere is collapsed and trust into the atmosphere and at a level of 1 ATM expanded again as a balloon and a Sabatier reaction will be started until the flotation force of the sphere filled with the H gas at the ambient temperature is equal to the weight of the water and methanol produced(converting methane into liquid methanol on the side). The methanol can then be converted to plastics for construction of living spaces or more spheres and air-conditioners and the water used in biosphere preparation. [Answer] "2) What amount of energy is needed to run it?" You can *gain* energy by doing it, because the hydrogen is ionized. What you need is a kind of reverse Dyson–Harrop satellite. <https://en.wikipedia.org/wiki/Dyson%E2%80%93Harrop_satellite> ]
[Question] [ Follow up to this question: [How would earth goverments respond to killing of most of a colony to keep the rest alive long enough for rescue](https://worldbuilding.stackexchange.com/questions/27301/how-would-earth-goverments-respond-to-killing-of-most-of-a-colony-to-keep-the-re) but with a different approach. The same scenario occurs. The first colony to mars suffers a disaster. To clarify points form last time this is an early colony designed only to prove that mars colonization is possible. It has no children, only 1,000 highly skilled men and women who signed up for a dangerous proof-of-concept mission. These men and women come from multiple nations and was launched as multinational effort, spearheaded by most of the big superpower economic nations. The colony has been on mars for a year or two. It has managed to create a system that can produce sufficient food to provide for all colonists, even a slight excess. Things are looking good when martian weather strikes, the equivalent of a tornado or other natural disaster strikes the dome, a freak accident as the odds of such a storm occurring and striking the small colony were absurdly low. The hydroponics area is destroyed, as is much of their com equipment. They know that Earth will realize they lost coms within a day or two when they don't make their schedule communications and start to organize a rescue mission. However, it will take some time to organize and reach them and they lack the food to survive that long. The governor makes a difficult decision, he arranges for 600 people to be killed to save the remaining 400 from starving. He arranges to poison their food supply, without telling anyone beyond a very select few required to enact the plan because he knows some of the citizens would not cooperate. He uses a semi-random approach. He selects some that must survive (like anyone with knowledge on how to keep what limited food production they still have running), and a few that will definitely die due to other illness and any who have had an emotional breakdown from the stress and are no longer functioning. He also selects a few groups of which he needs to ensure at least one survive, for instance one of 3 trained in servicing the life support must survive etc. Beyond those he picks to save to preserve the colony he arranges for most of the rest to have a random chance of being poisoned. In total he decided the absolute fate of ~75 citizens, the rest are given a random chance rather or not their poisoned. On other catch, he chooses to poison himself, knowing that he will almost certainly be sentenced to death for this decision were he to survive. He does, however, ensure his second in command will not be poisoned since someone needs to lead. He does not explicitly tell his second of his plan, though it's clear that the second could easily infer it was going on the governor orders him not to ask any questions and simply focus on learning everything needed to prepare him for keeping the colony alive until rescue comes. those few others who knew about the plan are all poisoned as well. When rescue arrives most of the 400 not poisoned are alive but close to starvation, in fact another 100 or so die before the situation stabilizes, since the rescue mission did not know to bring a stockpile of food and even though they could help fix the hydroponics to start growing food it would take some time before the colony could again sustain itself. It is impossible to evacuate all of the colonists back home with the first rescue ship, so many are left in a partially repaired colony. The Earth people have been watching this news during the many months it took for rescue mission to be set up, sent, and reach mars. During this time they had mostly given up on any of the martians surviving, until word comes of their partial survival and of the slaughter that happened. My question, how will society respond to this news? All the collaborators who arranged the killing are already dead, though the second in command, who was chosen to be saved, was in a position where he likely could have inferred something was going on, knowing the governor clearly had a horrible plan he wasn't talking about and didn't expect to live after it etc. First, will the world lash out at the second in command who was saved, and did lead the colony quite successfully in crises until rescue arrived by trying to punish him? Secondly, what will the cultural and political ramifications of one of the worlds first huge multinational attempts to reach out to space failing like this have? How will the survivors be treated, particularly those unknowingly chosen by the governor to survive without being part of the deadly lottery? Will hostilities be sparked over it, or will they world unite around those that survived what they had long ago decided must be an unsurvivable situation? Will the mars colony experiment survive, or will they give up trying to repair the rest of the colony and instead evacuate the rest of the survivors home over subsequent missions? Keep in mind ships sent to mars, for evacuation or with supplies to do a more perminate repair to the dome, are extremely expensive. [Answer] Society’s initial reaction to the second in command is likely to be positive rather than negative. He inherited a nightmare life-or-death situation from his predecessor and, presumably through his actions, kept most of the remaining survivors alive until reinforcement and rescue. There will undoubtedly be a massive investigation that examines his possible complicity in the events, but that investigation is likely to target all remaining survivors. There will probably be pockets of conspiracy theorists who believe the entire event was orchestrated by the second in command, but without concrete evidence this view should be in the minority. The broader ramifications of this event depend on some of the details, particularly the nationality of the major players such as the governor and the second in command. There are certain to be disagreements among involved governments about the morality of the governor’s actions and associated responsibility. This definitely has the potential to trigger inter-governmental strife internationally. Wars won’t be fought over this, but relations may be strained and future colonies might simply be pursued by individual nations. Survivors will probably receive some public adoration for their involvement in the project and substantial support after the tragedy. The more significant impact would be relationships between survivors. Knowing that you were chosen (or selected) instead of friends or loved ones would be very troubling. Hostility between survivors could be common and emotional trauma would be widespread. This would be a hellish experience that would almost certainly result in varying levels of PTSD for the majority of survivors. If this actually happened, it would be disastrous for an international colonization effort. However, that is mostly because this event **should never have happened in the first place**. The sequence of events described here demonstrates considerably poor planning in mission design and a massive failure to provide adequate redundancies. One thousand people on Mars would require an enormous amount of infrastructure. For something as predictably dangerous as Martian weather to knock out the most critical functionality of the colony, with no ability to mitigate the damage, requires ineptitude by colony and mission designers. If an international coalition decided to launch this mission in the first place, independent investigations by participating countries would certainly ensure that such a colony never happened again. ]
[Question] [ Firstly: I'd like to note that this post ( and the world it's based in) is partly inspired by the time travel mechanics of the game [Achron](http://en.wikipedia.org/wiki/Achron). If you're confused by my question go watch some videos of that, then you can be confused by them too. With that out of the way: Let's establish some rules for time-travel. 1: There is one timeline. While parts of the timeline may be affected by effects that no longer exist, there isn't a concept of 'multiple' timelines except in an abstract sense. 2: Any changes to the timeline propagate forwards at the same speed as time. If If I jumped back in time and didn't affect myself at all, there would be a ten year 'epoch' at the front of the timeline in which only one of me existed, but the rest of the timeline would have the history in which I arrived. If I were to jump back ten years and kill myself, it would take ten years before that change reached the point where I jumped. 3: As a consequence of 1 and 2: Paradoxes do not resolve. Instead they form multiple state 'flip flops' in the timeline. Using the example above: I jump back ten years and kill myself. It then takes ten years for me to reach the point where I otherwise would have jumped from. My lack of jumping changes the timeline of ten years ago back to it's original state, which then takes ten years to repeat the process, leading to a paradox with a period of 20 years. These paradoxes never resolve, but will continue to bounce between states forever, sending 'waves' of alternate histories (named 'epochs') down the timeline. 4: Messages can be sent between times. This is equivalent to a jump. If I send a message back to myself saying 'duck', the change it causes will follow the same rules as above. If the changed me also sends the message saying 'duck' this results in a permanent alteration to the timeline. If the changed me does not send the message, a paradox results. 5: It is not possible to detect when a message or traveller has come from (unless the message or traveller tells you), and similarly it is not possible to detect (without prior knowledge) where a message/traveller is going to. Ok. That's the rules out of the way. Now onto the scenario: A war has been raging, using time as a battlefield. Nobody knows how long the war has been going, because it's been lost in a haze of paradoxes and time loops. The war is formed into roughly two sides, and at some point these sides have managed to organise themselves with centralised command structures. It can be assumed that any soldier on either side will immediately and implicitly trust any messages they get via the time-communication devices, and that neither side can interfere with the other's time- travel technology directly. My question is this: Given that the paradox mechanics can result in constantly changing histories, and Epoch boundaries move forward through time constantly, how can either side establish a permanent command structure that won't eventually end up sending orders over itself? So far all I've come up with is jumping back as far as possible and setting up a (very well hidden) command post. Please note: This isn't actually of vital importance to any plot elements at the moment, but it's been bugging me that I can't think of a decent way to do it, and if I were to expand this world past the current narrative I've got going I'll have to address it. **Addendum:** You can assume that this universe is deterministic and ignore the vast majority of quantum level effects. Unless a traveller/message has an actual interaction with a system it can be considered to evolve in exactly the same way. As an example: If a traveller jumps to where a lightning bolt will hit it will route through them. If they jump twenty miles away the bolt will take exactly the same path as it would of without the jump occurring. [Answer] I am going to use "paradox wave" to refer to changes propagating through the timeline. This answer also assumes that if you jump through timelines, you're not longer impacted by paradox waves in the timelines you left. I'm sure this answer isn't perfect, but it outlines a conceptual way to keep things intact, and it's probably just as plausible as time travel is in the first place. **Paradox Detection** Each time communication and travel device will communicate with itself (sending messages back and forth one week apart) in order to detect paradox waves. To do this, the device will record its own kinetic movements. So being picked up, the user moving around, etc. Presumably a paradox wave that's significant would change these events because the user will taking different actions. Or they could be dead. This recording and communication is buried in the device and is normally inaccessible to prevent people from accidentally messing with their own timelines. It will then alert a user in the following scenarios: User+1 week will be alerted if User's kinetic pattern changes. User+1 week will be alerted if User's device stops sending responses/data. User will be alerted if User+1 week's device stops sending responses/data. This then allows a user to realize their timeline has been altered and take appropriate steps. **Restoring Command Continuity** After a paradox is detected, the command center will then have 2 weeks before the incoming paradox wave to resolve the issue. Note: I'm assuming 2 weeks because the "propagate at the speed of time" is kind of a really strange concept. Time being relative and only existing within the context of a timeline normally. But in this case, after "1 week" the command center has experienced half a week in their timeline, which means they're "ahead" of the paradox wave by 3.5 days. And at 3.5 days, they'll have another 1.75, and so on. It won't actually catch up to them until double the time of the paradox has passed. **Preventing Circular Paradox Waves** This system could result in additional paradox waves as people are alerted to other waves. In order to keep this from circling, they should observe the following protocols: Groups shouldn't resolve their own paradoxes. So, establish multiple command bases. If Command A is alerted that they're about to be wiped out, Command B or Command C should be in charge of fixing it. When a Command is wiped out, they should re-locate to a new location entirely rather than attempt to fix and stay in place. **Stranded Command Groups** Let's use Command A as an example. Say they get hit by a wave, but are just altered and not wiped out. Command A+1 week relocates to preserve command continuity. Now Command A is stranded. You have two options. Option 1: "Kill" Command A. You don't necessarily have to literally kill them, you could just mark them as untrusted and out of the war. Option 2: Re-integrate them as a new command, with a new place in your overall organization structure. You'll want to re-evaluate everyone, check for plants, etc, to keep from being compromised. [Answer] This is only logically consistent only on a small local level. It is actually logically impossible in an attempt to prevent multiple time lines. Though you really DO have multiple time lines here. If you go back in time and make a change, everything following that change will have a 'different' reality. If I am killed as a child (as a target, not as collateral) none of my friends or family would know anything about me past that point in time and anything I would have done never exists. If I don't exist now, no one would go into the past to 'kill' ME, since I don't exist, but they might go back to kill my younger self. This leads to the 'paradox' in the example. The big problem is envisioning that 'time' is continuing in this loop over and over. To have any chance for this to happen anything like you are saying, then every time someone goes 'back' in time, time is reset BACK to that exact moment and **EVERYTHING** that had happened between 'now' and 'then' is 'rewound' and we 'start' over. Meaning there is only one true 'current moment' in time, everything else is the past already set in 'stone' and the future infinitely mutable. And sending someone 'back' erases everything back to that point in time, allowing everything to continue the same as it had before except for any changes that were made by the act. Anyone growing up in one timeline would never 'know' anything about the other, their lives have 'always' followed this path. EDT: Taking the idea of each change is a 'wave' of change slowly moving to 'update' the future and doesn't make an instantaneous or updated timeline. (and answer to Joe Bloggs comment) There is no possible control. If two groups are doing this you don't even have true control of where you are sending anything 'back' to. It could already be changed before they get there. I send a man back to talk to a SGT. but he hits a wave where that SGT was killed 10 minutes previously, so no one in the future would no he's dead. On top of that no one will know HOW any change is actually going to affect the future. 2nd add: If the time change 'waves' move at the same time as regular time, then they will never catch up to 'now'. I send a man back 10 years to do something, that change takes 10 years to reach 'now', but I am now 10 years in my own future when it reaches this point. I will never see the changes I am advocating for unless I have some kind of machine that can 'monitor' the time stream. (I think Star Trek has a group doing that in the far future). [Answer] Have them always follow the orders from the furthest forward orders, also, make sure to send the messages to a time exactly ‘x’ ago, so that orders from different times don’t overlap. As the changes go at the same speed as time, if a specific time back length is made, the changes will overall match up with the orders, meaning that the troops will get the proper orders, from the proper future, at the proper time. Ex. Jim sends message back 3 minutes, in the version where he gets the message, he doesn’t send it back. 3 min cycle created. By always sending messages back in a timeframe where it will always go with the correct alternations, in this case always 6 minutes ago. ]
[Question] [ **This question already has answers here**: [How much would a civilisation develop without war?](/questions/3885/how-much-would-a-civilisation-develop-without-war) (9 answers) Closed 3 years ago. Humans have a lot of wars. Regardless of the size or level of technological development of a group of us, we have a strong tendency to pick up weapons to go out and kill our neighbors. Not all creatures on Earth behave like this. Animals like elephants and bonobos may fight or even kill each other from time to time, but all out wars do not occur. It seems that if such a race of creatures were to develop into an advanced, tool using society, they may form a society without war. For a space-based RPG that I'm developing, I'd like to have just such a race of beings, but I'm unsure how evolving without war would shape both the creatures and the society. There are examples on Earth of non-warlike animals, but I'm unsure what causes these creatures to evolve this way or how a non-warlike nature would shape further development of an advanced civilization. If a race of sentient, sapient beings evolved without the need to go to war, what factors would shape and drive this evolution? What sort of evolutionary pathway would shape a race of pre-tool using creatures into an advanced society that does not fight wars, and in what major ways would the end being differ from a human? [Answer] War happens for one of two reasons. The first is scarcity; when two groups of people both need something (e.g. Access to a vital water source or fertile hunting grounds) bad enough to fight over. The second reason people fight is greed. Nation A has resources such as rich gold mines or abundant forests that Nation B wants. Nation B is stronger and the leaders of Nation B try to take said resource from Nation A. To stop fights from breaking out you will have to remove both scarcity and envy/greed from a society. This is **possible** with the technology of an advanced space faring civilization (greater chance of reaching post-scarcity). To get a species in which evolution does not favor competition they would have to have some sort of hive mentality - an ant colony does not generally have civil wars. Their ascension to dominance on their planet would involve a sort of [super colony](http://sciencenordic.com/ants-supercolonies-defy-evolution) that slowly grew to encompass every colony/hive/nest on the planet. I would imagine society would involve more individuality than an actual ant nest, with individuals linked mentally to a queen to keep them in line. Each queen might be linked to a sort of "super queen" for the same reasons with a single queen on the very top of the hierarchy. [Answer] Violence but no war? The two are separated by scale and level of organization. War is simply organized violence between two social groups. There are two ways to prevent it from ever happening. The species might be incapable of **organized** violence. If violence or threat of violence cause a strong emotional reaction that makes individuals incapable of large scale organization, the species will only have wars by proxy. It might use AIs or mercenaries. It might use underhanded methods and schemes to get results from smaller scale efforts at sufficient remove to enable rational planning. Some scifi settings have such species as an excuse for needing human mercenaries or giving humans a balancing factor for inferior technology. The species might only have a single large social group. They would still be able to think "me first" and "me versus others". But they'd only have "us against them" to the level of small family groups. There would be no nations, tribes, political parties or organized religions. Just me, my family, and the species as a whole. The species might be unable to group people into friends and enemies, which would have interesting consequences as such divisions are fairly fundamental and very strong in Humans. [Answer] You could erase the reasons that war happens in the first place. That means you would have to think of a way for that race to exist without the need to ever go to war. Some scenarios i can think of are: * Their world was always abundant/utopian and they coexisted peacefully with other organisms so their race evolved without the need for survival mechanisms. * They are all immortal and can die only if they wish to. * They are purely spectral beings and they cannot physically hurt one another so waging war is pointless. I hope I helped you [Answer] Your creatures must have some biological or environmental factor that prevents exponential population growth when they develop technology and civilisation. This will prevent competition for scarce resources becoming cause for war. They also have to be more altruistic and less greedy than humans. The first is the hard one. For an egg laying species, at least unwanted pregnancy ceases to be a factor. Now let's imagine there is an uneasy symbiosis with a tick-like creature that manufactures or injects some vital nutrient for its host, but which grows exponentially into a plague if the density of hosts becomes high. A bit hand wavy but it might work. As for altruistic and less greedy I find myself imagining sentient house sparrows. They pair bond for life and bond strongly in small flocks like loose extended families. They are highly gregarious with other flocks and other species. And they have *lots* of "affairs" outside of their pair bond yet only death of the partner can break that bond. If that happens they do not grieve and bond almost immediately with any unattached sparrow of the opposite sex. The new pair will continue to raise any orphaned chicks. Chicks are cared for and taught by adults long after they leave the nest. ( if you want comprehensible but alien social structures, look at the birds we share our planet with. Above is just one of thousands). You might also get an absence of war if the species were very strongly individual and capable of participating in a society only at a learned intellectual level. They could never accept orders for long enough to form any sort of army. You'd have (possibly ritualized) combat between individuals instead of wars. Hmm ... weren't Niven's Kzinti like this? [Answer] Suppressed ego allowing all members of the group to act primarily towards the common good. Expanded social consciousness ([monkeysphere](https://en.wikipedia.org/wiki/Dunbar's_number)), they would have to recognise every member of the species as part of their social group. In times of shortage the group pulls together to survive. In times of plenty, when greed would become an issue, the reduced ego means that they rejoice in the increased prosperity of the group rather than the individual. Since all members of the species are automatically members of the group, they can't fight an internal war. God help you if you pick a fight with them though, since a fight with one may well turn out to be a fight with all of them. [Answer] Wars are often fought for reasons that have nothing to do with economics - pride, vengeance, fear of being conquered ("a good offense is a good defense"), religion, culture, race (eugenics), lifestyle (individualism vs socialism), in some cases, a small event escalating to an out of control war and lastly, because people forget what a nightmare war can be, they may engage recklessly assuming it will be easy to "win", until they experience the hell of war again, and "remember". In other words, your humans would have to be: (1) Uncaring people that have no initiative, don't care if they get taken over by others, don't want anything, take no pride in their culture/religion/lifestyle/race/etc and don't mind if you come along and take their property or enslave them. That means they're either more like animals or doped up, stoned humans. -or- if they do care, and they believe war is a bad thing, then: (2) They have evolved excellent **peacemaking** skills - and culturally take pride in the skills of resolving differences and coming up with solutions where people can agree to live together in common cause. This would require the opposite of option 1 - a heavy amount of intelligence **and** wisdom combined with a the ability to **convince** others to change their minds. It also means that the vast majority are **receptive** to, and open to, thinking through the opinions of others, even if those other opinions evoke strong negative emotions. -or- (3) They're 100% logical - like Vulcans - and remove emotion from the process and focus on generating solutions to problems. [Answer] War is a way of dealing with exploitation - either a means to create exploitation (before, or after the initial reasoning to go to war) or a response to exploitation (seeking independence, emancipation, etc.) What you have either a society that totally accepts exploitation without friction, or one that doesn't have it. In the former, you might have an extreme caste system or some means of resolving conflicts that has no, or little bloodshed. This could be cultural - groups that are willing to accept exploitation (from minor lessened resources to out and out death) without fighting back, or it could be biological, like an alien species that falls into caste roles like bees or ants. In the latter, you lack large scale exploitation. People have pointed out that without scarcity, this is a possibility, however, there's many situations where we have engineered scarcity in our societies, so it is more based on the desire/inclination for exploitation than the availability of resources. Again, this could be cultural - an enlightened society where the members have risen above the need to dominate, harm, or take from others, but it's probably easier to consider a biological situation - a hivemind, or evolved colony creatures. [Answer] instinct. a for knowledge that war leads to extinction. a biological fluke that gives an added human need for survival.Not to take away from any experience of being human but to add to the Wonder of Being. ]
[Question] [ *Related:* * *[How would a completely urbanized city-planet be maintained?](https://worldbuilding.stackexchange.com/questions/813/how-would-a-completely-urbanized-city-planet-be-maintained)* * *[How would the global environment of a completely urbanized city-planet be affected?](https://worldbuilding.stackexchange.com/questions/811/how-would-the-global-environment-of-a-completely-urbanized-city-planet-be-affect)* * *[Why would a completely urbanized city-planet exist?](https://worldbuilding.stackexchange.com/questions/812/why-would-a-complete-urbanized-city-planet-exist)* Heavy emphasis on importing raw materials is often required by the city-planet in such worlds. Could enough material ever be brought fast enough to support the obviously enormous human population? On the flipside, could enough waste ever be removed fast enough? Where would it go? [Answer] Once the city-planet is completely built up, it would be very difficult to mine ore with which to make repairs to the extant buildings; presumably raw materials could be recycled for a while, however, and particularly decrepit areas could be torn down and turned into strip-mines in order to get more ore et al (stored in some buildings that are still standing for later). Agriculture would primarily have to be supported via hydroponics and rooftop gardens. There isn't anything particularly far-fetched about that, although high levels of pollution might make it difficult to grow plants in a way that keeps them safe to eat. But if we assume that a highly-urbanized planet means that everyone can simply walk or take electric rail to wherever they're going, that seems a bit more plausible. Animal farming would become much more difficult (but still not impossible), and I'd expect meat to become a luxury item with most people subsisting primarily on vegetables. Electricity can certainly be generated with rooftop solar and wind power, as well as from biowaste (both from reclaimed methane and from good old-fashioned steam power from burning it). Much of the biowaste would also be usable as fertilizer for the gardens. Oxygen sustainability almost certainly would become a problem; on Earth, most of our oxygen comes from rainforests and phytoplankton (i.e. the oceans), and deforestation would effectively cut our oxygen production in half. However, 21% of our atmosphere is oxygen and that's sustaining 7 billion people with plenty of room to spare, and only 0.04% is CO2. Even assuming that animal respiration is responsible for all that CO2 (which it isn't, as most of it comes from burning carbon-based fuels) that implies we could easily support several hundred billion, if not a few trillion, people with the oxygen in the air. (This doesn't mean that it would be particularly pleasant, of course, and we'd run out of other resources long before that, not to mention the *huge* impact that would have on the greenhouse effect.) Now, there's [about 57 million square miles of habitable Earth](http://www.zo.utexas.edu/courses/THOC/land.html); assuming that the entire habitable surface of Earth had a population density similar to, say, [Manhattan](https://en.wikipedia.org/wiki/Manhattan) (which isn't the densest but it's not exactly sparse either!) we'd have a world population of around 4 trillion people, which would definitely be too much for our atmosphere to support (unless we were to somehow replace a lot of the nitrogen with oxygen, which would have some pretty major problems even if it were doable). Based on the above, with 4 trillion people, we'd expect the atmosphere to be something like 58% nitrogen, 21% oxygen, and 21% CO2. The greenhouse effect would be enormous, and everyone would constantly feel like they're suffocating (from the air, if not from the constant panic of being deep in an urban area that never ends). Chances are, the added surface population would cause a massive algal bloom, making the oceans nothing but a giant oxygen factory. (This also accounts for where a lot of our waste would end up going.) So, in short, it might be physically possible, but it certainly wouldn't be pleasant. [Answer] Simple answer: Yes. If the civilization is capable of interplanetary travel, definitely even plausible. Long answer: The only way you'd conceivably support the population would be similar to how large urbanized areas are today, except on a galactic scale: huge amounts of inbound and outbound traffic transporting raw and manufactured goods in and carrying waste out. This traffic would need to be capable of reaching other planets in relatively short time periods (days, maximum). Some amount of self-sustaining is possible utilizing near-future technologies in farming. Namely [vertical farming](http://en.wikipedia.org/wiki/Vertical_farming), [indoor farming](http://10milefarms.com/growingfoodindoors/) and similar ideas. Although it may be easier/cheaper to import food as well depending on the interplanetary travel costs. Such industry would have a use for organic waste, such as sewage and reclaimed water, as well. At some point, however, the planet would run out of things like iron, gold, silicon, etc. so those would certainly need to be supplied from off-world. Asteroid mining, gas giant refineries, and so on. Similarly, non-organic waste would likely be processed in some manner to recover usable materials (recycling: plastic, metal, glass, etc.) the remainder might be shipped offworld and dumped on non-habital worlds, dropped into stars, or packed into the mined out empty cores of asteroids (ah the future's garbage dumps...). [Answer] I think the society would have to be very technological advanced. One big issue is energy. This would have to get out of the way by nuclear fusion or a dyson sphere. Once there is energy, [vertical farming](http://en.wikipedia.org/wiki/Vertical_farming) can be used to create enough food and control atmosphere. Some process would be need to create huge amount of organic matter, using rock and specialized plants / bacteria. With all that energy, a lot of heat would be produces, as energy usually ends up as heat. Energy efficiency is a must and some global cooling system probably as well. Controlling the atmosphere could help here. The next thing are resources. High level recycling is a must, obviously. Usage of organic materials, long lasting products that are shared etc. Creating building material from compressed ground. Only walking-distance travelling, collaboration in virtual environments. Or just put them all in the Matrix ;) I think that way, the city may actually be sustainable. Computer systems to solve complex tasks are emerging. These would be necessary, to control a city of that size. The ruling party, that may or may not be private (if that separation would exist anyway), would be the one in control of the software system. The executive force would be controlled by the "AI" and therefore by the ruling party, kind of like a bureaucratic hierarchy without the hassle. Or an AI is already ruling on it's own anyway, which could also be the reason for such an omnicity. In short: I think the key to a city like this is not import / export, but to gain total control of the planets resources, their transformation and the population. [Answer] **Raw Material:** This isn't a Problem at all. If you assume that you only build highbuildings like skyscrapers, this would be impossible without gathering resources from other planets. Not only due a deficit of materials like copper for power supply, but also i doubt that there's enaugh raw-material for concrete. Same Problem, when the world shall be completely covered in a mantling building. But: urban sprawl doesn't mean "building skyscrapers". The largest port of an urban environment is covered with small or middle sized houses. Therefor, I think, is enaugh material on our planet (wich doesn't must be equivalent to yours.) If all the buildings are made from the same material, this could be problematic. But as you see in different parts of the world, different materials are used. Like claim, stones, wood and so on. Low-craftet materials does not mean, that a culture is barbaric. **Waste:** You assume, that the way this world would handle their waste, is similar to ours. But if a civilisation can manage it to only, or mostly, use near to 100% recyclable materials, the wasteproblem is not a problem any longer. [Answer] You would need: **Energy:** Nuclear power, fission or fusion. Nuclear waste recycled or glassified and buried. **Electrical Food Chain**: Photosynthesis is just a way to knock electrons off atoms. In principle, it can be done with electricity alone. There's active research on this. Probably soon we'll have microbes that can produce sugar, fats etc from a current. More simply synthesize high energy compounds and let microbes eat them. Lastly, convert electricity to light, put plants under lights, stack as high as needed. Regardless of method, food is produced in highly compact areas in quantity year round. Carbon cycle remains closed. **Raw Materials** No real changes, everything recycled simply because there is no place to put waste. Mines and the like are just in the basement. ***Heat*** The real problem with a planetary city is heat. Urban areas are already heat islands, always hotter than the surrounding natural terrain. Cover the entire planet and you'd heat the entire planet. Might actually cover the entire top in reflectors because really you don't need solar energy (solar panels are thousands of times less dense than nuclear power and they'd generate more waste heat per kilowatt.) Presumably the planet starts as a terrestrial planet and has seas. Seas are the major heat conveyers on earth. They are powered by solar evaporation which changes density causes changes in density of seawater at top causing it to fall. If you build over the ocean you will stop the heat conveyers and the poles and the equator will have radically different temperatures which will produce storms. Likely, they will dump some waste heat back into the ocean to mimic solar effects and keep the conveyer going. The real problem will be radiate enough heat into space. There is a phenomena called "heat pollution" that will occur when just the heat dumped into the atmosphere by technology starts to alter climate and drive storms. Most likely a civilization advanced enough to build a planet city could figure out alternative radiators for the planet e.g. radiating lasers, magnetic radiators or just a bunch space elevator like structures that were just radiators carried huge amounts of heat from the ground to space. **Economics**: To my mind, the major technical road block to a planetary city would be one of what pragmatic or economic forces would drive that many people to pay the enormous price of cramming that many people together? Population will not grow as populations urbanize because children cost a great deal in urban areas and unlike under farming, produce no income until well into adulthood. Long before a planet gets paved over, population growth will be flat or even declining. Dense urban cores, especially ones with skyscrapers, were justified by the need to cram lots of people close together so they could communicate with analog technology. Such dense cores are already technologically and economically obsolete, though not with out their lifestyle appeal for many. We've long passed the stage where people had to be in New York to hit the big time. Major corporations are spread all over the world in urban areas big and small. It's as easy to send email around the world as in the same building. I think the most likely scenario might be a completely non-economic reason to cram hundreds of billions of people on a single planet. * A prison for a very large galactic civilization, perhaps locking up entire societies for some reason. * A refuge of some kind, everyone is there because it's the only place to survive. It could be a hiding place or a fortress. If the latter they would be like people fleeing the barbarians to hide in the castle. * Planet city, but mostly empty. For whatever reason, a lot more city got built than needed. Runaway autonomous construction robots is a scenario I've seen once or twice. In that scenario, the city becomes the geography with 99% of it empty but maintained the robots. Spooky. ]
[Question] [ I had an idea for my story for an advanced civilization to capitalize on possibly the most energetic events in their universe which is the merger of supermassive blackholes. From current observations of mergers it seems that ten percent of the mass of the smaller blackhole is turned into gravitational wave energy so for SMBHs (supermassive blackholes) this will be a tremendous amount of energy. It is predicted that, unlike the currently observed mergers of a few ten solar mass blackholes which produce its energy in less than a second but SMBHs will give off the large amounts of energy over a week or longer depending on their size. My idea is similar to a Dyson swarm but a very large swarm to cover the orbital distance of the blackholes as they reach the merger and the swarm must be large to have enough ships to convert what will be a small amount of the total energy but combined in their trillions over they can capture a high amount of the gravitational waves, if that is even possible? What method could be used to covert the waves into usable/storable energy using current or near future methods? Bounty notes: I had thought of @Goodies idea of creating a devise to turn the motion of parts into electrical energy as this method is similar to how they currently detect waves from the position of protons but I did wonder if there were better methods or what a large high tech version of that method would be like? I am looking for hard science answers but will also accept detailed theoretical ideas such as @Goodies suggestion of a more direct transfer of gravity to energy. I had thought that the concentration of space during the wave could increase virtual particle density which could be extracted with a sort of Casimir plate device for increased zero point energy. I would rather Hard-science answers but theoretical answers are welcome. On another note for bounty answers, can a gravitational wave dissipate in the same way that water waves can be dissipated or would it still pass through most matter even if some energy is extracted? As if it does dissipate by the swarm this could be used as defence method for civilizations in the merged galaxy. [Answer] Ok gravitational wave *season*, say it persists for 2 weeks, energy can be harvested for 2 weeks.. **How much you'd get** Depend how far away you are, of course.. these waves have huge energies, but after 1 billion light years space time *distance*.. there wasn't much left for little Earth. Forbes calculated it, *"From a billion light-years away, two black holes of 36 and 29 solar masses merged, converting about three Suns worth of mass into pure energy. By the time those waves arrived at Earth, they had spread out so only 36 million J of energy impacted the entire planet: about as much energy as Manhattan receives from 0.7 seconds worth of sunshine. "* From <https://www.forbes.com/sites/startswithabang/2020/05/08/ask-ethan-can-we-extract-energy-from-gravitational-waves/?sh=3559d37f1211> Now.. suppose such a gravitational wave persists for two weeks (you propose that, I'll handwaive), and the Forbes numbers are accurate, the wave that occurrered came from 1 billion light years away and it provided Manhattan (59.2 square km2 ) with 100% extra sunshine, for 0.7 seconds. (disclaimer: below calculations are not accurate, more like "in the order of..") What would be needed in terms of distance, to harvest that energy ? how near should your planet be, to get 100% extra sunshine, during two weeks, everywhere ? That would be 510,100,000 km² Earth's surface, not 59.. we'll need a factor 10 million times more energy to warm up the whole Earth. Also, you'll need to multiply the 0.7 seconds to get 2 weeks continuous energy so together, you're about 0.7/(24 \* 3600 \* 14)=5.78e-7, multiplied say you would need about 10e14 times *more* energy from the gravitational wave.. From an earlier topic I learned energy of gravitational waves is proportional to square distance so you need to take the square root of 10e14, that would be about 10 million. You should be 10 million times *nearer*.. the extra sunshine would happen if the two black holes would collapse at a distance of ca 100 light years, that is one billion light years (the original distance) divided by 10 million. **Concluding: at 100 light years distance, you can harvest 2x sunlight for 2 weeks everywhere** But again, your assumption about the two weeks spread MUST work.. if you don't have that spread, you'd be completely *fried chicken* when distance is only 100 light years and you'll get all energy at once, you'd have 10 million suns in the sky for 0.7 seconds. **To harvest it..** Night side of the planet would receive the extra energy too, it would be available 24/7 The Newton answer would be: you'd have to transfer very small mechanical displacements to larger ones. Tiny, but moves that allow huge, near-infinite reaction force. A *very* strong force. You could try to devise a gear system, to transfer that force to a rotator (generator) in some way. The Einstein answer I don't know. It may be possible to harvest energy directly, from the distortion of space time itself, gravitational deviations.. Say you drop a large weight, will it bounce back up again, and how to derive energy from that.. and how to prevent your workers from bouncing up and down too? **Creating perpetual motion (newtonian) using the gravitational wave** With gravitational waves, spacetime will show a standing wave in a certain direction, like you have at the sea shore, blue is background, red is the wave added by the collision, [![enter image description here](https://i.stack.imgur.com/oDpqN.gif)](https://i.stack.imgur.com/oDpqN.gif) Gravitation will vary, in a certain pace. How to harvest this ? Let's say the wave will be in a certain direction, you'll have a *band* over your planet where the variation is perpendicular to the planet surface. Space time theory sais, you'll have a gravitational force proportional to the *gradient* of the spacetime surface. An observer will notice a variable gravitational force when spacetime has a hight gradient (goes steep). Now suppose a large weight will be pushed upward, during a phase of small gravitation.. it would cost little energy, when the gravitational wave is in the *downgoing* position.. [![enter image description here](https://i.stack.imgur.com/15H7C.png)](https://i.stack.imgur.com/15H7C.png) When this thing would fall back with enhanced gravity, it would bounce back with more force, getting up higher than before. If you repeat it a few times, in the same rhythm, your heavy object oscillates ever higher up. Perpetual motion. You could harvest the energy when it is touching the ground and bouncing back, or in the end, collecting all energy gained in the process. [![enter image description here](https://i.stack.imgur.com/4Ru12.png)](https://i.stack.imgur.com/4Ru12.png) The mechanism could also be used to launch objects into space. [Answer] This is a good question, and a difficult task. Part of the problem is that most objects in the universe are effectively transparent to gravitational waves - they don't really absorb or scatter them, so energy transfer is quite difficult. [In 1969, Freeman Dyson calculated](https://ui.adsabs.harvard.edu/abs/1969ApJ...156..529D/abstract) that Earth should absorb a fraction $\varepsilon\approx10^{-21}$ of the energy flux of a 1 Hz gravitational wave passing through (although there is a dependence on the frequency $f$ of the wave, scaling as $\varepsilon\propto f^{-2}$). That said, under the right conditions, gravitational waves can dissipate *some* energy. There was some *extremely* speculative work about a decade ago ([Li et al. 2012](https://arxiv.org/abs/1203.0317)) arguing that gravitational waves emitted by a supermassive black hole binary (SMBHB) could deposit energy in an accretion disk and in nearby stars. A merging SMBHB of mass $\sim10^9M\_{\odot}$ could induce a luminosity increase of about 1% of the Sun's luminosity in a nearby star about 10% the mass of the Sun, lasting for about a week. This might seem like a pittance - and it arguably is - but it would still be significantly larger than the normal luminosity of that star by an order of magnitude or so. Therefore, one possible way to convert the energy of gravitational waves to something useful would be to indeed build something like a Dyson swarm, but have it surround nearby stars and take advantage of the luminosity increases in the aftermath of the merger (as well as the stars' typical output). This is arguably fairly inefficient and is extremely speculative - and if you're building a Dyson swarm, you might as well surround a much more luminous star than a red dwarf - but it would indeed convert the energy of gravitational waves into electricity, or some other type of energy of your choosing. [Answer] # Guiding the collapse of a binary Black hole: I will open with the fact that I am not a physicist and am shamelessly raiding Wikipedia for material. Since this is somewhat uninformed, I post it here mostly to see what ideas it provokes. PLEASE feel free to leave constructive comments. [The final Parsec](https://en.wikipedia.org/wiki/Binary_black_hole): Collision of two such black holes is an unlikely event. Instead, under ideal conditions (which are likely to require the intervention of a high-level civilization) You would have two supermassive black holes using the ejection of matter to cushion the stabilization of an orbit. More matter would be needed to guide the two stars closer and closer to each other (inspiral), and they would be likely to eject all available matter before the effective end of the universe as we know it. An advanced interstellar civilization could guide this process by manipulating stars as breaking and mass for this process. I have little doubt that the energy of this mass being ejected from the system of the black holes would be both vast and occur over an extremely long time. Harvesting energy from moving matter is a well-established process doubtlessly better done by a high-end civilization than anything we could manage. The continuing narrowing would involve the constant feeding of matter into the system and the release of energy. So we're milking the event from start to finish. The final cataclysmic event is supposed to release insane amounts of energy, and continuing gravity waves as the shapes of the black holes stabilize. The challenge is to figure out a useful way to store even a fraction of this power for a meaningful amount of time. I'm spit-balling a bit here, but can this energy be used to stretch a sort of cosmic string? It could be as "simple" as your Dyson swarm containing connected pieces with "elastic" chords that are then stretched, but I doubt an advanced civilization would depend on something so crude. SO what if you maneuver a [ring black hole](https://en.wikipedia.org/wiki/Ring_singularity) around your collapsing SMBH collision at the moment of maximum output? I don't know how large you could inflate one without blowing it apart, or if it would expand and immediately contract, but if you could make a super-wide, super-fast spinning black hole around your new SMBH singularity, and milk the energy of it as it shrunk, the potential energy stored in the system would be insane. ]
[Question] [ ### The World The setting is an endless sky of naught but pillowy white clouds and floating islands scattered across the skyscape. In such a world, how would the various nations, from small city-states to large empires, trade with, conquer, and otherwise move people and resources between one another? ### Geographic Details The islands sizes vary from small acre-large landmasses to landmasses the size of Australia (with the average landmass being somewhere between the size of Liechtenstein and The Netherlands). Some landmasses are closer to one another, and some further apart from one another. There are some groups of landmasses which are somewhat close together, with large distances between these groups and others. These are called Archipelagos (but can be thought of as possessing local diversity and complex international relationships in the local sphere much like a continent). The average distances between islands in the world is quite large. Even "close" islands are out of visual range for all but the clearest days with optimal light conditions, where they appear as small specks in the sky. "far" islands are tremendously far away and cannot be seen at all. Of course, there exist some islands which are significantly closer to one another such that even birds migrate between them, but most fall between the two bounds mentioned above. There is no correlation between any of the 6 cardinal directions and any effects on temperature, pressure, or other environmental features. There are indeed some cold and wintry islands, as well as hot barren desert islands strewn across the sky, but the climate in these areas is unrelated to their position relative to their neighbours. **Note:** There exist strong "currents" similar to tradewinds in various places in the sky (due to concentrated flow of mana / Ley lines / dragon veins). These currents are rather localised and can be though of as behaving similar to a slipstream, speeding up travel along their course. They don't cover the entirety of the sky; but split and merge in a complex network which doesn't double-back on itself. The currents are dynamic, but take up to hundreds of years to split, merge, or move by any great degree. ### Viable Aerial Creatures There are no man-made airships, but there are a variety of tameable wyvern sub-species (which can effectively be grouped as "big" and "small"), as well as sky whales. Wyverns are bipedal reptilian creatures possessing webbed wings. The big wyverns can be thought of as being capable of carrying up to ~3 people, and the small wyverns only a single passenger (the pilot). Sky whales are gargantuan creatures, many times larger than an actual whale and up to hundreds of metres\* long. They are peaceful creatures, flying from island to island, but are out of the control of humans. Big wyverns are capable of making the journey between close islands at maximum capacity with ease, and they can make the journey between far islands with fair difficulty and at reduced load. Small wyverns can *just about* be able to make it to close islands, with far islands out of the question. Sky whales are able to fly indefinitely with ease. **Note:** If it helps, there are *technically* dragons as well, capable of carrying many tens of people, however they are noble and intelligent creatures of incredible power, and would only ever offer their assistance if particularly enamoured / interested by a human or situation. Unlikely to volunteer for goods delivery. ### Current Ideas With the exception of invading close smaller countries, which *may* be possible with a collection of large and small wyverns, and given the restrictions provided, I feel that sky whales offer the greatest potential as a large-scale logistics solution. The primary concerns that remain unresolved being that the sky whales are meant to be the paragon of freedom, and having them work with / subordinate to the terrestrial races would compromise this image. * Sky whales will often fly by islands and loiter about before being on their way. **Pros:** Sky whales retain their "freedom" and means they can have goods loaded onto them (somehow). **Cons:** For the sky whales to be loaded up with cargo implies knowing where they're headed next. With a clear migration pattern, they feel less whimsical and free-flowing. Unless docked, loading and unloading cargo would be a complex operation perhaps requiring smaller aerial creatures. * Once near an island, sky whales are benefited by some form of hospitality such as cleaning, prompting them to dock. **Pros:** Similar to above, but more conducive to large-scale logistics operations. **Cons:** Feels either like the sky whales are being used, or otherwise like a quid-pro-quo arrangement. Both of which detract from the imagery with which they are to be associated. I'm hoping for some form of solution that allows for the fairly large-scale logistics that would be necessary to facilitate complex trade / military events; either by modifying the above ideas or recommending new ones. I'm happy to clarify or expand on any of the above points. \* I'm bad at approximating sizes. Maybe larger, maybe smaller. Gargantuan nonetheless. [Answer] I think flying animals is your best bet, it seems like a good fit to your story, that said: * [magic](/questions/tagged/magic "show questions tagged 'magic'") is allowed. Awesome. + Transportation scrolls. - These could be made available by the destination town, and sold by the equivalent of a tourist agency. + Levitation spells. - Can be used to levitate the sections of a bridge. Magic has a maximum range from the mana source, so both sides need to cooperate the keep the bridge up. + Human flight spells. + Magic carpets. + Transportation spells. - As an interesting weakness, you can only transport to a location you can see, or that you've been before. But you can take someone with you. - This means your mages need to train a new generation in order to allow people to visit another island. If your mages are killed, you're permanently isolated. - Mages have been doing this the old days, when the lands were joined together. - If a town loses their mages, it will be permanently isolated. * Technological solutions: + There are natural fibres which can stretch beyond visual range without breaking. Eg [Spider silk, pine fibres, Oak fibres](https://en.wikipedia.org/wiki/Specific_strength), glass fibre may also be easily made and is on that list too. That implies it's possible to create a rope that spans two islands. + Airships aren't allowed, but a hot air balloon requires large fabric processing and that's about it. + Since we can have long ropes, giant kites can be used with known prevailing winds to transfer humans and people in one direction. Kites can be trimmed to steer them to fly at an angle to the winds. + If there's mountains with updrafts, hot deserts, or dark fields, simple gliders can be made, rise up on the thermals to several km up, and then travel the distance. A decent modern glider can get 16:1 ratio - if you can get 4km up (air starts to thin), you can travel 64km. The first glider flight was 1850s - so not a lot of tech needed. * Mixed technology / magic: + Give people a parachute, a helmet, and then the village mage uses magic to accelerate them in a ballistic trajectory towards their destination. The mage can't see the island at the required resolution to land them on the surface, so aims a few km up and then they fall using the parachute. + Use magic to run ropes between two islands, and then build a bridge between the two. Maybe use magic to bless the ropes with super strength too. + Use magic weight changing spells, so that you can fly there with hand-held wings. (In Sci-Fi we'd call this "Inertial dampeners") + Use the magic transportation with the "you must see where you're going" weakness, but societies invent powerful telescopes, allowing them to see further. [Answer] If Your islands are floating like boats on a some ethereal, unseen sea, why not use them as boats. Assuming that whatever is keeping then in the air only affects the rock (or a part of the rock) and increases in strength the deeper you go, then you would be able to change height by adding/losing weight, maybe by collecting rain or maybe having ballast islands, larger islands that transfer ballast from islands that want to go up and add it to islands that want to go down. You could have propelled by winds (via parachute like sails) or you could have them towed around by some of your creatures, even if they can't carry the entire weight they can still drag it, akin to dog sleds or canal boats, and when they get tired that can rest on the island. Large islands/continents would be stay approximately at the same spot, as the high mass would make then very hard to move, and/or the winds maybe keep pushing them to the same spot. Hopefully that helps. [Answer] **Cable car system** Overall this would operate similar to movable islands but assuming the islands are stationary. Create a system of heavy "undersea cable" like constructions running between two islands, where each cable system is able to support the majority of the weight of some gondola. Since the cables carry the vast majority of the weight then the gondola need only be dragged forward by small wyverns. When needed the wyverns can rest on the gondola or slipstreams can be used to push the gondola along the path. Let's also say that the gondola can have an any maximum carry weight depending on size and construction. Ideally we can ignore friction unless breaking, either through magical means or technological. To handle the construction of this system one or two large wyverns would run an initial very light line to a far off island. After the initial line has been set use this line to carry some of the weight of a heavier line, which is guided again by the wyverns. This whole process can be repeated as needed until eventually a very heavy line could be run which would allow for a gondola system to be established to move people and goods at a large scale. While it would take many wyverns to run these heavy cables over a large distance the support from the previously run lines would allow for them to have the ability to carry much larger loads without much of a major issue. Not being able to see the islands is not an issue the cables would have the ability to carry most of the weight of the goods in the gondola and the gondola itself can be dragged by the wyvern, if kites or sails are allowed then where possible the slipstreams can be utilized to further improve transport speed and if needed wyverns can rest on the gondolas as required. This could open up an eventual rail network like scenario where there are certain lines that can handle say, 1 tonne vs lines which can handle a maximum of 500 Kg all of which are built up using this series of support cables which are dragged by wyverns in the beginning. *Edit* The above assumes that the material for the cable is enchanted or otherwise created such that it is able to support its own weight over any given distance. This can be done in the following ways 1) defining the material to be incredibly strong and light, ie Mithril. 2) by saying that there is an enchantment on the material which allows it to be strong enough to support itself. 3) The material is suspended additionally by some type of enchanted connection to the slipstreams nearby providing energy for supporting the load of the cables. Magic can also be used to help the wyverns to support the weight in the initial flight ]
[Question] [ What light spectrum would hit the surface of a planet orbiting a red dwarf star? The planet is a humid greenhouse with a cloudy atmosphere and a strong ozone layer. Over 80% of the surface is water. The planet is tidally locked to its star. I'm trying to determine plant life on a world, and the type of light it would absorb or reflect. Any additional considerations would be appreciated as well. [Answer] # TL;DR As most of the other answers say, the plants on this world would likely be purple-ish, using photosynthetic pigments that operate at the same wavelengths as bacteriochlorophylls. Chlorophyll a and chlorophyll b wouldn't receive as much light in the visible part of the spectrum as they do from the Sun, meaning that green plants would be inefficient and therefore comparatively rare. We would likely even see pigments that operate primarily in the infrared portion of the electromagnetic spectrum. ## What does a star's spectrum look like? The overall spectrum of a star - ignoring emission and absorption lines - can be approximated by the [Planck function](https://en.wikipedia.org/wiki/Planck%27s_law), which describes the spectrum of a perfect black body and depends only on that body's temperature. From the Planck function, we can determine things like the wavelength of peak emission, or how much of the star's light is visible to humans. The Sun's surface temperature is roughly 5800 Kelvin; a red dwarf might be closer to 3000 Kelvin. As such, its spectrum looks a little different - weaker, and shifted to longer wavelengths. This favors pigments with peak absorption at longer wavelengths. Here's a plot of two black body spectra (representing the Sun and a red dwarf), normalized to have the same maximum spectral radiance: [![Spectra of the Sun and a red dwarf](https://i.stack.imgur.com/RSrwn.png)](https://i.stack.imgur.com/RSrwn.png) ## A brief detour: Spectral lines Feel free to skip this section if you want; it's not directly related to your question, but does elaborate on what a star's spectrum might look like. Star's aren't perfect black bodies, but it turns out that the major deviations from a pure black body spectrum come from the composition of the star's atmosphere, which isn't uniform. There's hydrogen, yes, and a lot of it, but also heavier elements like helium and silicon and iron and magnesium. The elements lead to the formation of spectral lines, which appear as sharp dips and spikes in the otherwise smooth black body spectrum. These don't have a huge impact on the star's luminosity, but they do form the basis for distinguishing different types of stars from one another. Spectral lines vary in strength and shape due to a number of factors: * The temperature of the star, which affects how much of each element is ionized. * The stellar atmosphere's composition, which provides a baseline for whether certain lines should appear. * The surface gravity of the star, which (along with other factors) can make spectral lines broader. In M-type stars like red dwarfs, [titanium oxide](https://en.wikipedia.org/wiki/Titanium(II)_oxide) bands are strong; as titanium oxide breaks down at higher temperatures, it's seldom seen as clearly in hotter stars like the Sun. ## How about clouds? You say that your planet is largely cloud-covered, which *could* have an impact on what light comes through. The thing is, this is highly dependent on the composition of the clouds. Clouds of water transmit light differently than, say, clouds of carbon dioxide. It does seem that this transmission/scattering [is (at least weakly) wavelength-dependent, and it could have an affect on pigment concentrations](https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1998JC900002). This is something to keep in mind if you end up developing this world in more detail. ## What photosynthetic pigments will be useful? Here we get to the meat of your question. Once we have a star's spectrum, we can figure out what sort of [photosynthetic pigments](https://en.wikipedia.org/wiki/Photosynthetic_pigment) will thrive on a planet orbiting it. On Earth, the most successful of these pigments are chlorophyll a and chlorophyll b, which have absorption peaks near 400 and 600 nanometers, centered around the peak of the Sun's spectrum. Now let's see how the stellar spectra compare to the absorption spectra of different photosynthetic pigments. I got data from [omlc.org](https://omlc.org/index.html) for [chlorophyll A](https://omlc.org/spectra/PhotochemCAD/html/123.html), [chlorophyll B](https://omlc.org/spectra/PhotochemCAD/html/125.html), and [bacteriochlorophyll a](https://omlc.org/spectra/PhotochemCAD/html/135.html), and plotted their extinction spectra superimposed over the spectra of the two stars: [![Spectra of the Sun and a red dwarf, overlaid by extinction spectra of different pigments](https://i.stack.imgur.com/iertA.png)](https://i.stack.imgur.com/iertA.png) Note the absorption peaks for the chlorophylls near the peak of the Sun's spectrum. At these wavelengths, there's little emission from the red dwarf, meaning that chlorophylls wouldn't thrive around such a cool star. Bacteriochlorophyll a, on the other hand, has peaks around 800 nm, closer to the wavelength of peak emission of the red dwarf. Bacteriochlorophylls, as well as related pigments that flourish in the purple part of the visible spectrum and at near-ultraviolet wavelengths, would likely be the dominant photosynthetic pigments on your world, making for flora that are much less green and much more purple. [Answer] Speaking of a hypothetical Earth-like planet (plus tidally locked) it would resemble something like [this](https://steamcommunity.com/sharedfiles/filedetails/?l=czech&id=101632999): [![source:https://steamcommunity.com/sharedfiles/filedetails/?l=czech&id=101632999 ](https://i.stack.imgur.com/knLf0.jpg)](https://i.stack.imgur.com/knLf0.jpg) The planet itself would be divided into 4 zones, 3 of which would be technically uninhabitable: a perpetual hurricane on the side facing direct sunlight, a twilight zone (tormented by endless winds) and the icy biome, covering pretty much the other half of the planet. The only habitable zone would be the zone of indirect insolation, where life could thrive and evolve, in a range of temperature varying from over 104°F in the western regions to even less than 0°F in the Eastern part. Now, Ozone is the major absorber of UV rays. If the layer was thicker than it is on Earth, then it could potentially absorb all UV rays. Less UV rays means less risks of skin cancers or insolations for us humans, but it could gradually lead our bodies to a Vitamin D deficiency (with consequent low calcium levels). Increased humidity levels could cause the hurricane located in the point of maximum insolation to grow bigger and thus more extreme temperatures in the transition "habitable" zone (with the tropical one becoming even more humid and the Eastern one colder). Finally, as far as [vegetation](https://www.nasa.gov/centers/goddard/news/topstory/2007/spectrum_plants.html) is concerned, we know that the chlorophyll in most plants here on Earth absorbs blue and red light, but (suprisingly!) less green light. Therefore, chlorophyll appears green to us. Green is still absorbed, but less than all the other colors. On a red dwarf world, since the light peak is in more in the infrared, leaves would try and catch every photon they could since it would require a larger amount of them to complete photosynthesis. I guess leaves would appear darker (even black) than here on Earth, but I'm not too sure about that. I don't even think there would be life in the oceans either, since light would be too weak to penetrate water below 10/20 meters. [Answer] The planet would have to be closer to the red dwarf star. <https://www.spaceanswers.com/solar-system/what-if-we-replaced-our-sun-with-a-red-dwarf/> Also, on flora, plants would be differently colored. "As a result, astrobiologists have suggested that photosynthetic plants on worlds orbiting lone red dwarfs could take on hues of red, blue, yellow, purple, or even grayish-black to best absorb the starlight," (From link below). Red dwarfs give off less light and because the planet has to be closer (than, for instance, Earth's distance from the sun) to the red dwarf. <https://news.nationalgeographic.com/news/2011/04/110419-alien-trees-black-plants-planets-ras-space-science/> There is also the issue of solar flares though. Red Dwarfs give off solar flares more powerful than the suns. With the planet being closer these flares could easily kill all plant life unless it could somehow shrink away and hide during these flares. <https://www.universetoday.com/140302/a-red-dwarf-blasts-off-a-superflare-any-life-on-its-planets-would-have-a-very-bad-day/> [Answer] ## Spectral Stuff For the emission spectrum of the star you'll need two formulas. Wiens Displacement Law [1] and the Planks Law [2]. *Wiens Displacement Law* $ λmax = (2.898 \* 10^{-3}/T)\*10^9$ $T$ = stellar temperature in Kelvin Obtain temperature via this formula. $T = M^{0.505}$ $T$ = stellar teperature relative to Sol (multiply by 5778 K) $M$ = stellar mass relative to Sol *Planks Law* $Bλ(λ, T) = ((2\*π\*h\*c^2)/λ^5)\*(1/(e^{h\*c/λ\*kB\*T}-1)$ Have fun figuring this one out. ;) Or use this calculator [3] ## Atmosphere You mentioned Water Vapor, Ozone and CO2, as greenhouse gases. If you aim for a human breathable atmosphere consider these limits. O2 = 0,16 - 0,5 atm, but only up to 35 % of atmosphere (runaway wildfires will keep it this low) O3 = 0.0000001 atm Co2 = 0.02 atm (gets uncomfortable at 0.005 atm) Be aware that greenhouse or hothouse atmosphere are used to describe Venus like conditions. You don't seem to aim for that. Should you want to calculate the greenhouse effect on this world I'm gonna have to stop you right there. Nothing short of a PHD grade physics simulation will give you precise values. But I do have a list of linear approximations derived from calculating stuff backwards. These are by no means scientifically accurate, but they will do for worldbuilding. $H2O = 677 K/atm$ $O3 = 19600000 K/atm$ $CO2 = 13784 K/atm$ Don't let the planets teperature get above an average temperature 47 Celsius, as this marks the beginning of a runaway greenhouse effect [4] leading to Venus like conditions. This again is just a ballpark number. You shouldn't go under an average temperature of - 56,6 C as CO2 will have frozen out at this point. These are the limits of habitability. Using these a way more elegant than calculating habitable zones and dropping the planet there. You will get the planets temperature without greenhouse effect [5] via the following equation. $T = (\frac{ L\_{\odot}(1 - a)}{16 \pi d ^ 2 ơ}\;.)^{1/4}$ $L$ = Luminosity in Watts Obtained via $L = M^3$ ($M$ is relative to Sol, Sol L is 3.828×10$^{26} W$) $a$ is the planets albedo, [6] and [7] should help you there. $σ = 5.670373 × 10^{−8} \;\mathrm{W}\; \mathrm{m}^{−2}\; \mathrm{K}^{−4}.$ this the the Stefan-Boltzmann constant. All that said a these formulars are tuned to an earth like sun and many things like the albedo and greenhouse effects of the gases will be altered by the new spectral class. But going for something more accurate is material for several scientific papers and not for a SE answer. ## Tidal Lock Assuming that the planet is tidally locked is sensible, but tidal locking does not always mean that the same side points towards the sun. Mercury is an example of a tidally locked world in a higher than 1:1 spin-orbit resonance [8]. As the eccentricity of the tidally locked planets orbit increases, the most likely spin-orbit resonances go up from 1:1 to 3:2 to 1:2 to 5:2. Just be aware that you will get strong distance based "seasons" as eccentricity increases. Just run the temperature formula for pericenter, apoapsis and apocenter. As the average eccentricity of discovered exoplanets is at 0.3, higher than 1:1 resonances seem very realistic and increase habitability. ## Additional Consideration It is very likely that you came across the concept of an eyeball planet [9] during your research for this. Sources and people who give you this information are not up to speed. The eyball planets are an artifact of early simulatiins without oceanic and atmospheric heat transfer. There will be strong, constant winds carrying warm air from the near point to the far one. Temperatures on the night and day sides will be close to equal. And if there is a frozen ocean the ice free hole won't be round, it will be lobster shaped. (If you want I'll go source hunting, tell me in the comments.) Small stars like red dwarfs tend to be variable, flare or UV-Ceti stars [10]. They can increase their luminosity suddenly be orders of magnitude. Imagine the sun suddenly getting way hotter and brighter for a few hours and you see the problem. It isn't clear if all small stars are variable, as they become calmer as they age. Yet even ancient Barnards Star has been observed to flare. This needs to be considered while designing the biosphere. ## Plants **Color** There is no definitive answer here, just a jungle of possibilities that might all be true. Youtuber Artifexion made a video on the subject suggesting that plants use either the peak radiation of their star for photosynthesis or reflect it to use the other, less intensive light [11]. On earth the secound approach is used, resulting in green plants. On red dwarf planets this would result in black plants as they would want to use all the light. Should the star be variable some kind of biological flare warning system, maybe an UV-detector and the ability to protect against or survive the flare will be crucial. Land plants will be more affected than sea plants. So rolling up like Shameplants, burrowing, using the stellar inferno for reproduction like Mammoth Threes or springing up rapidly after the flare like Eukalyptus does after fires seem like useful strategies. The first approach is great but there is one huge caveat. Biochemistry isn't a wonderbox. Xenobiology might hold many wonders but a chlorophyll equivalent for every set of wavelenghts seems unlikely. Earths green plants don't really use all the blue and red light, chlorophyll a and b just have absorbtion spectra covering a part of both wavelenghts. The various chlorophylls c and chlorophyll d have other functional wavelenghts and there are various bacteriochlorophylls. Interesting for our purposes is the recently discovered chlorophyll f, capable of using infrared light with wavelengths between 707 and 800 nm [12]. This would lead to plants which ignore the entire visible spectrum or only use some red light via chlorophyll din addition to the infrared light. This kind of vegetation could be white or bright blue-green-metallic respectively. This kind of reflectiveness could allow for flare survivability. [1] <https://en.m.wikipedia.org/wiki/Wien>'s\_displacement\_law [2] <https://en.m.wikipedia.org/wiki/Planck>'s\_law [3] <http://www.spectralcalc.com/blackbody_calculator/blackbody.php> [4] <https://en.m.wikipedia.org/wiki/Runaway_greenhouse_effect> [5] <https://en.m.wikipedia.org/wiki/Planetary_equilibrium_temperature> [6] <https://en.m.wikipedia.org/wiki/Albedo> [7] <https://youtu.be/y3Kb_ik5f-I> [8] <http://www.skymarvels.com/infopages/vids/Mercury%20Spin-Orbit%20Resonance.htm> [9] <https://en.m.wikipedia.org/wiki/Eyeball_planet> [10] <https://www.aavso.org/vsots_uvcet> [11] <https://youtu.be/L9MNC45Jr6Q> [12] <https://en.m.wikipedia.org/wiki/Chlorophyll_f> [Answer] There is an [episode](https://stargate.fandom.com/wiki/Space) of Stargate Universe which speculates that a red dwarf star would lead to [purple plants](https://stargate.fandom.com/wiki/Purple_plants%27_planet). [Answer] If the planet is tidally locked to its star, then one side would always be facing the star and the other would get no light. This would create huge temperature differences between the side facing the star and the side not facing the sun. As hot air is less dense, this would also create enormous pressure differences. The winds resulting from these pressure differences would be immense, as well as a constant hurricane in the middle of the side facing the star created by a perpetual depression. The soil would be eroded so much by these winds that I doubt that any soil fit for plant life would remain in a goldilocks temperature area. Furthermore, any plants that grow would have to have thick, strong branches and trunks to stand against the winds. This may be difficult to evolve, as any smaller trunks or branches would immediately be broken and blown away. ]
[Question] [ This may seem similar to [this question](https://worldbuilding.stackexchange.com/questions/28458/anatomically-correct-phoenix) but my goal is for one: The bird does not die and secondly to get more exact solutions. The ultimate goal would be to create a bird which can ignite itself at will for one or two minutes, while surviving. And to fix the flammable material storage problem (space and weight). (applying our physics and chemistry) So I have found out that apparently burning [isopropyl](https://en.wikipedia.org/wiki/Isopropyl_alcohol) when cooled with enough water can be cooled down to 56 degrees Celsius. (from the perspective of the bird the actual fire is still way hotter) A bird should survive this for one or two minutes. (can't provide my sources because [the us government is unable to pay](https://www.commerce.gov/news/blog/2018/12/shutdown-due-lapse-congressional-appropriations) the servers where I found them) The problem with this solution is: 1. How can a bird access isopropyl? 2. How does he ignite it? 3. How does he store enough water and isopropyl while staying streamlined? Another way entirely to solve the problem would be to use a light, isolating material replacing the feathers or adding it to the feathers. Which could enable me to use the same technique I used to let a Dragon breathe fire. The problem with the Dragon solution will probably be how to store enough flammable material in a bird. [Answer] **Farts** As we all know, cattle and some humans can produce inflammable farts. This is because we produce considerable amount of methane and hydrogen in our intestines. Unfortunately this is unlikely to be a working solution for birds. No extensive research has been done on birds farting but most students of birds seem to agree that they fart very little. > > Mike Murray said in a 2009 article for Popular Science, birds are > capable of passing gas, but they don’t because they lack the same > combination of diet and gas-forming bacteria in their gut that gives > mammals their odorous gas. > <https://www.dailydot.com/parsec/do-birds-fart/> > > > One supposes that given a very specialised diet (of beans?) a bird species could evolve to fart a lot but it seems unlikely for birds of a size that can fly. The larger flying birds are carnivores. Small birds' farts just wouldn't be voluminous enough for much of a display. **The Uropygial (preen) gland** > > [The] Uropygial, or Oil, Gland, in birds, an organ located on the back > near the base of the tail. Paired or in two united halves, it is found > in most birds. Absent in ostrich, emu, cassowary, bustard, frogmouth, > and a few other birds, the oil gland is best-developed in aquatic > species, notably petrels and pelicans, and in the osprey and > **oilbird**. <https://www.britannica.com/science/preen-gland> > > > The very name oilbird seems promising. Let's investigate. > > Nesting in colonies in caves, oilbirds are ... the only nocturnal > flying fruit-eating birds in the world. They forage at night, with > specially adapted eyesight. <https://en.wikipedia.org/wiki/Oilbird> > > > Clearly a bird that is flying at night is going to be *spectacular* if it bursts into flames but is their oil flammable? Yes it is. > > The oilbird, or guacharo, is not a morbidly obese bird. It’s called > “the whale of the air” because like its larger, ocean-dwelling > brethren, it contained oil—oil that was harvested yearly, and which > **lit lamps**. > > > --- So my suggestion is that some offshoot of the oilbird started to over-produce flammable oil from its Uropygial gland. The reaction to this would be excess preening. This oil would be spread all over the bird's feathers. So what causes them to burst into flames? **The crop** Many birds digest their food by eating small stones that are kept in the crop and act as a grinding mechanism. Let us suppose our birds live in a flint-rich area. They pick up small flints for their crop. Flints are well known to produce sparks. **The disaster** Birds that are over preening and spreading flammable oil all over themselves may occasionally get some of the oil in or near the flints in their crop. The flame ignites and of course the bird flies off in alarm screeching wildly. The flames spread backwards over the feathers increasing the conflagration. This is most likely to kill the bird but it would explain why people occasionally see these amazing aerial bonfires at night and report them back to their sceptical friends thus creating the myth. Alternatively these are water-birds and they instinctively dive into the nearest river or lake thus extinguishing the flames and surviving. --- **Evolution** Over time the birds that burst into flame and *die* are weeded out of the population. Some birds survive in better or worse condition. > > Breeding Plumage: This is the most brilliant, colorful plumage for > many bird species, and it is displayed during the courtship season > when birds are trying to attract mates. In dimorphic species it is > most often the males that develop bold breeding plumage, and it may > involve extraordinary colors or unusual feather shapes such as long > streamers. <https://www.thespruce.com/bird-plumages-387315> > > > When males, who are in their mating plumage survive being on fire they become very attractive to the females for their survivability and toughness and so tend to have more offspring. As generations go by, the males start to 'deliberately' set fire to themselves during the mating season and (like the peacock's tail) it becomes a feature that is kept going by sexual selection rather than simple survival. The males' mating plumage develops an outer layer of fluffy feathers that are easily set alight once preened selectively with the previously mentioned oil. This burns off leaving the lower flight feathers intact. New feathers can be grown fairly rapidly (feathers are growing and being shed all the time). Males that can both set fire to themselves and quickly regrow their mating plumage are obviously healthy individuals and so they become even more attractive to the females and we get ... **Fisherian Runaway** > > Fisherian runaway or runaway selection is a sexual selection mechanism > proposed by the mathematical biologist Ronald Fisher in the early 20th > century, to account for the evolution of exaggerated male > ornamentation by persistent, directional female choice.[1][2][3] An > example is the colourful and elaborate peacock plumage compared to the > relatively subdued peahen plumage; the costly ornaments, notably the > bird's extremely long tail, appear to be incompatible with natural > selection. <https://en.wikipedia.org/wiki/Fisherian_runaway> > > > Over the millennia the display becomes more and more spectacular for no other reason than the females prefer it. [Answer] # The birds have two layers of feathers. **The layer closest to the skin is fireproof.** Not 100% because that would be extremely difficult, but enough to last 1-2 minutes. They will not ignite in that time and they provide some insulation from the worst of the heat. **The layer over the insulating layer is wispy and light and extremely flammable.** If you've started a campfire you know that certain starter materials (like straw or thin flat paper strips) catch fire easily then burn themselves out very quickly, usually without getting hot enough and staying alight long enough to catch your kindling on fire. Think of a candle wick which stays cool enough to snuff with a quick pinch of wet fingers. In this case the wick stays lit because it is long and the wax slows the process down so that the wick needs more time to find more wick to burn. Your bird won't have wax or anything else to slow down the process. So the wick (the top feathers, which are short) just burns out and the flame dies. The flammable feathers are close enough to catch each other on fire, just like throwing a lot of paper into a campfire will catch. These feathers are perfectly spaced. They're close enough for the fire to spread but not so close together that the fire flares and gets terribly hot. The bird's feathers do not have "kindling." By that I mean, there is no in-between layer where the quick burn of the wispy feathers will transfer to an easy to burn but more solid layer and then set the "logs" on fire (in this case, the insulating feathers or the actual body of the bird, all of which will burn in the right conditions). The top layer of feathers grows back very quickly. **Only the bird's back is on fire.** The wispy flammable feathers are only on the bird's back, where they are most visible and prettiest. The bird's head, neck, limbs, and belly only have the insulating type of feathers. **When catching fire, the bird immediately moves into "fire position."** Its back faces straight up (because heat rises and that is the best way to stay cooler, if not cool). Some articles about fire-eating talk extensively about that. The most important technique is to make sure the fire points upward and you only contact it from below. This reduces the heat significantly. ([ref1](https://www.smithsonianmag.com/arts-culture/penn-jillette-reveals-the-secrets-of-fire-eating-132787272/?all)) ([ref2](http://mentalfloss.com/article/20672/how-do-fire-eaters-eat-fire)) The bird tucks its head towards its belly and pulls in its wings and feet and tail. Like a hedgehog. [![enter image description here](https://i.stack.imgur.com/pqkvw.png)](https://i.stack.imgur.com/pqkvw.png) ([ref](https://www.museum.ie/Natural-History/Exhibitions/Current-Exhibitions/Irish-Fauna)) A more experienced bird could move around and even fly while on fire. But this is an advanced technique for only the most foolhardy showoffs (or the most awesome, depending on your point of view and if you're a potential mate...or a parent). **Once the top feather layer has burned off, the fire goes out.** There is nothing to sustain the fire. It was too fast and too small to allow any other part of the bird to catch fire. The bird resumes a normal position, shakes it off, and kvells. ]
[Question] [ Because of reasons, I need a sword that needs to be on fire and still be effective. I've found [nitinol](https://en.wikipedia.org/wiki/Nickel_titanium), a shape memory alloy that when hot reverts to a preconfigured shape. If it reverts, would it actually STAY in shape when it's thrusting or slicing an opponent? According to [this other forum](https://www.reddit.com/r/SWORDS/comments/5am5bt/what_would_beis_the_most_durable_sword_material/) it should work as good or better than steel as a standalone blade when at room temperature. As for *being* on fire, I need it to burn for **at least 10 minutes**, but 30-60 minutes would be very convenient. I figured it could have a small tungsten shell hollow built into the spine of the blade (single-edge blade) that has a store of oil inside. This would communicate heat to the blade but still take the brunt of the heating effect. Otherwise the character could carry an urn of oil and just lather the blade with it, but how long would you conjecture that would last? Character is 1.5x stronger than a warrior-joe, so there's some leeway in terms of weight though not a whole lot. As an extension to the initial I thought I could take some magical liberty and say that's a blade that never loses its edge because it uses the thermal energy running through it to maintain edge alignment and structural integrity. Could all of this work? Or at least is it a ***small*** stretch? Thanks! [Answer] [![Beric with flame sword](https://i.stack.imgur.com/YXvMa.jpg)](https://i.stack.imgur.com/YXvMa.jpg) I have been curious how they did the burning sword on Game of Thrones. A chance to read up! I found this. <http://www.makinggameofthrones.com/production-diary/2012/12/6/prop-closeup-berics-flaming-sword.html> > > The fight-sequence sword is a real sword that the workshop team milled > with a number of channels, each one stuffed with a dura-blanket > material. The flame retardant fiber is then soaked in IPA (isopropyl > alcohol). This was then covered in another layer of material to make > the blade look uniform and sword-like again. Because of the length of > the sequence, the flame has to last (and burn strong) for at least 3 > minutes, which was something of a challenge, as the fuel burned off so > quickly. > > > In the prop sword they had mineral wool fabric reservoirs in the sword that hold the alcohol. Which is pretty similar to what you propose with the store of oil inside the sword coming out. I was surprised (and skeptical) to read that they used isopropyl alcohol. Those flames are strong - I thought probably turpentine or kerosene. The higher the molecular weight of the fuel, the longer the burn time. One could have higher molecular weight fuels which would burn longer but the problem is they will go out without the ample gas phase fuel. I think it is the lack of a big surface area / oxygen interface. You can make that work with pitch or tar but it is because the structure of the torch distributes the fuel over a bristly rope or straw surface; that would not work with a sword. Watching videos of burning magnesium or white phosphorus - they either burn like mad for a second or two or go out. Maybe a mix of tar and kerosene - kerosene to provide the gas phase / surface area and the tar for extra flame and heat? A problem with that as a prop is that bits of flaming hot tar might fly off and stick to things. Or the best: marshmallow creme! [Answer] Nitinol, by what I can find about its properties, could in theory be usable for a blade. It is harder than typical sword steels but doesn't seem to be particularly brittle and its density is slightly lower than steel's. There are two concerns I have: the material might not be stiff enough to work as a weapon, its elastic modulus is considerably lower than steel's. Furthermore, if I understand the mechanics of its memory shape properties correctly there are temperature ranges to be observed. If the blade is on fire for prolonged amounts of time, this might not be a positive change. As to the method of creating the flame: fire needs oxygen to burn, so you can hardly have it happen on the inside of the blade in a closed tungsten tube. My first question here is what you need the fire for: is it enough for the blade to be hot, or do you need flames on the outside? And how hot and how fiercely burning do you need it to be? Following Will's research on GoT's flaming sword, a few channels seems to be enough to produce a visually satisfying effect. Assuming we can preserve the blade's structural integrity while milling a low amount of narrow channels into it which are filled with a non-flammable but absorbent material, storing fuel inside the weapon could be feasible. I would caution that as soon as the fuel store isn't full, the liquid will swap around, making the sword much less agile to wield. I'd also assume that using the hilt and/or pommel would make for a better fuel store than the blade, as blades need to be rather thin in order to be able to cut. For fuel itself, Kerosene should be the best compromise between long burning and practical flame. Diesel produces a lot of soot and isn't that easy to ignite, although it burns for longer, and alcohol burns out very quickly. There are longer burning solid fuels - Hexamine is quite popular these days - but a solid fuel would require a much more complex construction that frankly I can't think of a way to make work. Ten minutes at a minimum is a long time to burn for liquid fuel though and your storage space is massively limited. Maybe a special scabbard construction that also contains fuel and coats the blade in it while it's inside could add to the burning time? In any case I don't see this working without modern technology. [Answer] There are a lot of types of Nitinol/SMA out there, basically, you can change its properties related to heat. Really, you can actually check it on some online shops like Ebay, Aliexpress and others, they show the temperature options for your Nitinol order. The most common and cheapest type is "superelastic" Nitinol, basically, they adjust the temperature in which the metal comes back to its original shape to room temperature; so, in simple terms the metal immediately goes back to its original shape as soon it is bended (in room temperature), thus having a "superelastic" property. [![enter image description here](https://i.stack.imgur.com/ofVAf.png)](https://i.stack.imgur.com/ofVAf.png) It is normally used by dentists to keep your teeth in place. [![enter image description here](https://i.stack.imgur.com/chfQa.png)](https://i.stack.imgur.com/chfQa.png) Once I bought one of those just to experiment with (since they are super cheap), I heated it directly in contact with fire from a oven for more than 10 minutes and even though it changed colour, it was still quite **though to bend**. If a single wire (like the one in the image) can be this though, I **think that a sword with quite the substance to it could handle it even better.** I think it would be a quite good material for swords, since steel is quite resistant/ductile, which help with impacts. However, I don't know if your world have the technological capabilities to actually make nitinol. ]
[Question] [ There is a terrestrial planet called **Paveiha** that orbits a small Red Dwarf star. It is the third planet in a system of 10 planets. Paveiha is close enough to the Sun that it is tidally locked and the planet itself has three moons. Two small irregular moons and one major spherical moon, **Jeah**, which is the focus of my question. I have some statistics regarding the Sun, Paveiha and Jeah below. I don't know if this is enough information to accurately answer my questions, but at least confirming my suspicions that Jeah is in a deaccelerated orbit would be enough. Information on the Sun, Paveiha and Jeah. # The Sun [![The Sun](https://i.stack.imgur.com/EpfgX.jpg)](https://i.stack.imgur.com/EpfgX.jpg) * Type: Red Dwarf * Spectrum: M3.1 V * Diameter: 373,136.28km. *(26.8% the diameter of Earth's sun)* * Mass: 0.24119 solar mass. * Age: 9.1 billion years. # Paveiha This map only shows the habitable (star facing) side of Paveiha. Clear white areas are water. The borders on the edges represent the beginning of the night side / icy region. [![Map](https://i.stack.imgur.com/G2XC2.jpg)](https://i.stack.imgur.com/G2XC2.jpg) * Diameter: 8685.88km * Mass: 0.31375 Earth mass. * Density: 5.4628 g/cm3 * Axial Tilt: 0'28'30'68° * Gravity: 0.6767g * Perihilion: 0.07 AU * Semimajor Axis: 0.07 AU * Eccentricity: 0.011 * Orbital Period: 13.958 days. * Orbital Speed: ? * Hill Sphere Radius: 113903.23km * Influence Sphere Radius: 72413.71km * Roche Limit: 6446.83km * Atmosphere Surface Pressure: 0.402atm * Atmospheric Composition: • 48.2% oxygen (O2) • 41.2% carbon dioxide (CO2) • 10.4% nitrogen (N2) • 0.196 sulfur dioxide (SO2) # Jeah * Diameter: 1261.09km * Mass: 0.00082409 Earth mass. * Density: 4.7828 g/cm3 * Axial Tilt: 0'12'56'87 * Gravity: 0.084319g * Perihilion: 17627.07km * Semimajor Axis: 18181.17km * Orbital Speed: ? * Eccentricity: 0.30 * Orbital Period: 12 hours, 6 minutes, 37.31 seconds. # I have two questions regarding Paveiha and its moon, Jeah. **1.** Is Jeah in a deaccellerated orbit? Is it possible to determine how long it will take for Jeah to collide with Paveiha or spin out of orbit? How long? **2.** How does Jeah's close orbit affect Paveiha? Would there be strong tidal forces? ***2.1.*** Would it have any effect on its oceans? ***2.2.*** Could the tidal forces disrupt life? [Answer] # Simulation setup I ran a simulation with your worlds in [Rebound](http://rebound.readthedocs.io/en/latest/index.html) using Python. I have my setup on github if you want to [take a look at it](https://github.com/kingledion/worldbuilding). The file is ``` orbit_noble_170301.py ``` # Results I ran the integrator a few times with different time steps. For dt = ~12 hours, Jeah immediately left orbit of Paveiha and fell into orbit around the main star. Then after 4200 years, it had a close encounter with Paveiha and the last I was tracking it, it was about 0.7 light years away from the star and going fast. I switched up the time steps and did some other modifications (not of the orbital parameters) but it never took more than a couple thousand years for Jeah to get ejected. My thesis is that Jeah is just too light. Paveiha is 3 Mars's or half a Venus, but Jeah is a relatively puny Titania or Haumea size. It is about 1/20th the size of our moon. I was guessing that it was just too small; given that it wouldn't stay in orbit of the main plant (too close to the star I'm guessing), it was too light to stick around in the solar system. So I tried increasing the size of Jeah by a factor of 10. This was a little better. Instead of getting ejected it tended to settle out in an orbit at around 12 AU (hope there's no gas giants!). # Conclusion I could not find a stable orbit for Jeah around Paveiha. I didn't even have to try integrating millions of years overnight; Jeah got stripped from the planet into an orbit around the star in a few decades. If you want to give this a try by yourself, try to add yourself at my github and then we can talk there. I can try to help you set up rebound yourself, if I have the time. [Answer] Let me preface this by saying that, as a mortal, non-omnipotent being, I cannot know all outcomes. I will do my best to answer with what I as Worldbuilder think may happen, but keep in mind that what I say doesn't have to apply to your world. In other words, take what's I say with a grain of rice, and feel free to use your own interpretation. . In regards to your queries, let's first take a look at your world, and compare it to our own Earth/Moon System. Luna is approximately 27% the size of earth, and at its furthest is about 405,000km distant. This translates to about 1.985 x 10^26 N of gravitational force between the two objects. Jeah, on the other hand, is about 14.5% the size of Paveiah, yet is only 17,000 km from its parent body. Considering the size ratio between parent body and Moon, your moon and planet have a size ratio half as much as the ratio between Earth and Luna, yet is also 27x closer. This translates to around 1.857 x 10^26 N of force. . Given the calculations above, here are my conclusions. 1. No, Billy-Jeah isn't in danger of crashing down anytime soon. 2. Given the size ratio and distance between parent body and child body, Jeah's gravitational effect shouldn't be too different from the current tidal effects on Earth. Keep in mind, though, this is assuming that Jeah and Paveiah share Earth and Luna's makeup; if, say, Jeah was made completely of iron, then this estimate is off. 3. Gathering the increased level of oxygen, it's possible that Earth-style creatures would have increased energy. Big bugs, stronger animals, and more flammable areas. This, though, is assuming that the extra oxygen doesn't KILL them; too much of a good thing, after all... 4. Given the previous information, it's safe to say that the far side will definitely have permanent ice. But the nearest point to the star's light would receive the maximum amount of solar radiation it could get. Given that there's a huge hunk of land there, this'll likely mean that weather patterns will be driven partly by temperature differences, with hot air of the near side rushing away to meet the cool air from the far side. This should translate to a belt of vegetation between the two zones, and rainstorms would likely be frequent along this area. 5. That, I cannot answer adequately, I'm afraid. Because that would require me to make a whole host of assumptions about my species and its current level of technology. Even with humanity, we're only good enough to give a "maybe" for whether a planet even has liquid water on its surface. The fascinating point, really, is whatever you set it to be; beauty, as they say, is in the eye of the beholder. . Hopefully this answered some of your questions. ]
[Question] [ Let's say I have a character whose body stopped aging at say 7 years old, prepubescent; just say [a wizard did it](http://tvtropes.org/pmwiki/pmwiki.php/Main/AWizardDidIt). The individual is now into their 20s, but their body never ages and, in particular, they never go through puberty. What sort of effects will it have on the mind to never go through this phase? Will they think or feel differently because of this? For instance, I imagine they likely would not be physically attracted to the other sex, having little sex drive? Would they be less aggressive due to lack of testosterone? Basically, how will the lack of the usual chemical concoction of crazy that is puberty affect someone who has matured mentally without going through it? Edit: in terms of sex I'm more interested in a male, but would love answers for both sexes if sex becomes relevant. Hmm...maybe I should stop saying the word sex on a question about a 7 year old in which the word 'pedophile' already exists in comments... [Answer] In many animals, including humans, the young go through a "learning and experimenting" phase in which they're very curious and very open to new ideas. Eventually they leave this phase; they become less interested in learning, and more interested in doing well for themselves with the world as they understand it. It's difficult to know how much of this phase transition is "hormonal" versus how much is based on the person getting older and simply deciding they have enough experience, but I'd speculate that someone whose body was frozen at a young age would feel more playful and more curious than someone who aged normally. I also agree with you that not going through puberty would likely make a person less aggressive. --- But probably the most important effect to think about would be the social effect on a person who always *looks like a child*. This person is mentally an adult, and presumably would like to be treated like one, but everyone they meet reacts to them like they were a little kid. When they say something, nobody listens to them or takes them seriously. People tell them to "run along and play"; people ask where their parents are and who's taking care of them. Even their friends, people who know they're mentally an adult, have to keep fighting the reflex to treat them like a small child. This person's approach to social interaction is built around this problem. Everything they do is focused on the need to compel people to take them seriously. They might act very aggressive, because (1) nobody will get seriously angry when threatened by a little kid, but (2) the threats just might compel them to treat the kid as a real person. They look for ways to appear more important -- standing on things to look taller, wearing formal clothing, et cetera. They might spend a lot of time online, where their age wouldn't be visible. Or they might spend most of their time with a few close friends. They'd probably find it pretty stressful to interact with strangers -- if nothing else they'd get really tired of having the "yes I'm old enough to count as an adult" conversation over and over. I think this effect would mostly override the effects due to hormones or lack thereof. [Answer] Addendum: from <https://rpg.stackexchange.com/questions/71719/playing-a-child-oracle-in-pathfinder-how-to-prove-age-and-how-open-will-populat> I see that you're actually thinking about doing this in a system that has magic. In a world with magic, looking important becomes much easier. People have already learned that someone who isn't physically imposing can still have great magical powers. I imagine most villagers, if they encounter someone who doesn't look like an ordinary villager, will immediately assume: "Oh, this is a shapeshifted dragon, or a case of demonic possession, or a curious planar traveler, or an elf prince, or an adventurer with a weird curse, or something to that effect; whatever it is, it's way above my CR and I should get out of its way." If your character wants to "blend in", an easy option is to buy a [hat of disguise](http://www.d20pfsrd.com/magic-items/wondrous-items/wondrous-items/h-l/hat-of-disguise) and make himself look like an adult dwarf or halfling. If your character just wants to be recognized as an adventurer, any magical-looking prop will do the trick. For example he could carry around a wizard staff, or he could cast [continual flame](http://paizo.com/pathfinderRPG/prd/spells/continualFlame.html) on any of his possessions. After your character gains a few levels, he'll be carrying around enough magical-looking knickknacks that his adventurer status will be obvious even without special effort. Basically all medium-level adventurers will be wearing a fancy cloak (usually a cloak of resistance) at all times, and villagers only wear cloaks if it's cold out, so a cloak becomes a clear signal that "oh, this person is an adventurer". [Answer] I expect a protagonist with mentioned features to feel underestimated (no wordplay intended), which causes stress, anger, etc. S/he is to manage it or not. **His/her expectations will be slightly or majorly backdrawn by the chances/possibilities given, comparing to a standard same age one, so the life experience will trend in that way too.** Most probably s/he will choose to attend activities, which s/he can blend in socially for mind age 5-10, later something which involves no conflicts of body type expectation. Like reading. S/he might be even considered to be talented child as long as the peers do not realize the situation...but maybe even so. Parental surroundings are high time for an age of 7, it is a major factor to calculate with. With a mind of 20, s/he may stick with the idea being or acting as having this typical body issue. Plenty depends on the mind's motives. Like is it rebellious, or avoiding conflicts, or fighter type. Is his body gifted with above or lower average (not mythical, just normal diversity of same age bodies) strength, dexterity, toughness, etc. Is he actually a charmer or not (or same in girl)? Maybe some refined description would come handy. [Answer] I highly recomend either reading the book or watching the movie "The Curious Case of Benjamin Button". sort of has a similar story to your character and he aged in reverse, he was born old and grew young, ending up with a child's body and and old mans mind. it's a very good story. ]
[Question] [ **This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. In [this question](https://worldbuilding.stackexchange.com/q/22573/2071) about a Mars battle set up in 2100-ish, we decided, that the best battle devices would be [drones](https://worldbuilding.stackexchange.com/a/22575/2071). In that setup the whole "drone" thing was hand-waved, but I would like to know if it is doable: * **Year:** 2040-ish * **Setup** 6th mission to Mars. We want to discover more area by having drone with us. Such a drone will be guided by Mark Watney (I am bad in names :)) from Martian ground. **Questions:** 1. Is drone feasible at all? For this drone = device which is heavier than atmosphere, but uses atmosphere (either wings or rotors) to keep itself above the ground 2. I am assuming that such device would use rotors. How big rotors do I need to keep 5 kg heavy drone above martian ground? 3. I am assuming battery powered drone. How much energy do I need? *Limitation:* Please stay at current level of technology. Basically, you can only use whatever exists now, because I have assumption that what is "cutting-edge" by today standards, it will be "sturdy enough to survive on Mars" by 2040ish **Edit:** By "drone" I did imagine something using rotors: [![drone](https://i.stack.imgur.com/n6ky7.jpg)](https://i.stack.imgur.com/n6ky7.jpg) *Image credit: [Wikipedia](http://en.wikipedia.org/wiki/Unmanned_aerial_vehicle)* Generally, I would like to have something which can fly and maneuver above a relatively small (maximum 1km) area. Please note the [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'") tag. I want you to put down some elaborate guesses. Extra points for doing so. [Answer] I'm incredibly embarrassed to be chasing the bounty here, but I can't resist the challenge. Besides, drones are cool. Okay, to start with this, we need to know just what developments have been made in this area. The major project in the rotor-powered-drones-on-Mars field is the ESA's [Dropter project](http://www.esa.int/Our_Activities/Space_Engineering_Technology/Dropship_offers_safe_landings_for_Mars_rovers)1, from the StarTiger initiative. The Dropter project is not meant to be directly channeled into a Martian probe, but is merely a test of technology. Its flight envelope has not been particularly pushed; in its final test (under Earth surface gravity and atmospheric pressure) the drone was used to reach a height of 17 meters before descending and lowering a rover to the ground. It was guided at first by GPS and then by visual data. There are some difficulties associated with chucking the Dropter onto Mars and seeing what happens: * There is no GPS network on Mars. As noted in [GPS / Iridium for human presence on Mars?](https://space.stackexchange.com/questions/4768/gps-iridium-for-human-presence-on-mars), there is currently minimal demand. However, [NASA's Deep Space Network](http://mars.jpl.nasa.gov/msl/mission/communicationwithearth/navigation/) solves those problems with a large network of receivers, so the positions of all autonomous craft are known. The communications delay could be an issue, though. * The Dropter has not been tested in conditions like those on Mars. The StarTiger team rigged up a recreating of the Martian landscape, but the atmosphere was still the atmosphere on Earth, and the surface gravity was still the surface gravity on Earth. [NASA is researching conditions for aircraft on Mars](http://www.nasa.gov/centers/ames/research/technology-onepagers/mars-airplane.html), but a lot is still up in the air. Also, most designs proposed are fixed-wing aircraft, not rotorcraft, and the rotorcraft designs have been small, as noted in [Young et al. (2004)](http://rotorcraft.arc.nasa.gov/publications/files/Young%202005Mars_Rotorcraft_IEEE_Final.pdf). Young et al. (2004) is the most in-depth study on Martian rotorcraft that I could find. It's eleven years old, but it does cover some rather important points that I'd like to mention: * **Range:** Smaller scout drones - along the lines of your idea - are probably limited to an operational radius of 50 km. That's rather large, especially for a scout craft. It will also be perfectly fine for your specifications (1 km). Larger (manned) craft could reach distances of a couple hundred km. * **Energy use:** Rotorcraft - especially small ones - take up a lot of energy compared to traditional rovers. There are, of course, some advantages to flying, primarily being able to travel over large obstacles (e.g. mountains and canyons) at comparatively high speeds. * **Rotor mass:** Martian rotors must be lighter than terrestrial rotors - perhaps only one-tenth as massive. This severely constrains choices of materials. [Young et al. (2002)](http://rotorcraft.arc.nasa.gov/publications/files/Young_IEEE02.pdf), a related study, focused on the types of craft you seem to be looking at: small, light drones with scouting ability. In that study they listed some requirements and calculations for drones of this type, typically weighing 10 to 20 kilograms: * Two rotors, with four blades per rotor * Rotor radii of 1.22-1.72 meters * Top cruise speed of 40 meters per second * 50 km range They also discuss tests that have been done2: * Single-rotor hover tests in a simulated Martian atmosphere * Coaxial rotor hover tests in a simulated Martian atmosphere * Tests of visual navigation techniques3 One important test that had not been done as of the publication of the paper was the choice of power, between electric motors (with regenerative power technology) vs. an Akkerman hydrazine engine. The latter is based on ideas by [Akkerman (1978)](http://manufacturingscience.asmedigitalcollection.asme.org/article.aspx?articleid=1446105) (paywalled!) and mentioned in [Young et al. (Date?)](http://halfdome.arc.nasa.gov/publications/files/Young2000Mars_Workshop.pdf). A good comparison for propulsion is [Young et al. (2001)](http://rotorcraft.arc.nasa.gov/publications/files/Young_ERF01.pdf). The Akkerman engine provides greater power, but electric motors are cleaner and have no harmful waste products. Electric motors have their issues too: fuel cells can produce contamination, and solar power isn't always easily accessible - or enough. More investigation has been done, and specific designs have been covered (see [this NASA slideshow](http://solarsystem.nasa.gov/docs/03_Rotorcrafts%20For%20Mars%20Exploration_Balaram.pdf)). Here is the design given in that slideshow: ![](https://i.stack.imgur.com/T6qtx.png) Notice the coaxial rotors, a common feature in designs for Martian rotorcraft. So, answering your specific questions: > > 1. Is drone feasible at all? For this drone = device which is heavier than atmosphere, but uses atmosphere (either wings or rotors) to keep itself above the ground > > > Absolutely. Most studies are optimistic but agree that it is possible. > > 2. I am assuming that such device would use rotors. How big rotors do I need to keep 5 kg heavy drone above martian ground? > > > You can get a 10 kg drone off the ground using rotors 1.22 meters in length. > > 3. I am assuming battery powered drone. How much energy do I need? > > > That depends on the mission capabilities and other instruments on board, but 1550 watts for a 10 kg craft should be fine, according to Young et al. (2002). --- 1 "Dropter" is a contraction of "dropship" and "quadcopter". 2 All tests are from during or before 2002, when this paper was published. 3 These would have been the precursors to some of the navigation used for the Dropter project. [Answer] Wikipedias article [Mars aircraft](https://en.wikipedia.org/wiki/Mars_aircraft) leads us to [Sky-Sailor](https://en.wikipedia.org/wiki/Sky-Sailor). This is a 2.5kg drone that would fly using 13.2Watts of solar power. So for a 5kg probe I would suspect between 26.4 Watts(linear growth) and 105.6 Watts(cubic growth) is reasonable guesses. Sky Sailor has a wingspan of 3.2 meters and is a fixed wing aircraft though, so it's not cabably of hovering. It's also not intended to be capable of take-off, instead it's released from a spacescraft after athmospheric entry. [Answer] According to [wiki](https://en.wikipedia.org/wiki/Atmosphere_of_Mars), average pressure on Mars is 0.6 kilopascals (0.087 psi), while atmospheric pressure on Earth is 101.3 kilopascals (14.69 psi) - the pressure on Mars is 170 times lower, than on Earth. According to [Roto craft altitude record](https://en.wikipedia.org/wiki/Flight_altitude_record#Rotorcraft), the Rotorcraft can operate on heights of 12,442 meters. The pressure on this height is 3-4 times lower than on sea level, still at least 50 times higher, than on Mars. I think Mars atmosphere is too thin to support rotor craft. UPD: by rough estimations, the 5kg machine need to have 10m rotors. UPD1: probably you can build flying drone as big dirigible, but it is not a combat device - it is really easy to detect and shot. Sand buggy / tank with machine guns looks more realistic for me, or even the bipedal bot like in Red Faction looks more realistic [![bipedal bot like in Red Faction](https://i.stack.imgur.com/I3VOp.jpg)](https://i.stack.imgur.com/I3VOp.jpg) [Answer] Personally, I'm not sure that drones would really be the ideal way to do battle in the hypothesized scenario. The problem with your hovercraft idea is that the hovercraft itself is fairly useless unless you're trying to annoy them to death. You could put some small guns on the hovercraft then shoot at people, but you're not going to do much once they realize you're shooting at them. They'll just wait inside until you run out of fuel. You could use the hovercraft to plant explosives, but it's going to be tricky to get the explosives somewhere useful. It would probably be much easier to design a self-guiding missile with a fairly large explosive payload and just destroy critical sections of the enemy compound than to design and pilot drone aircraft in some kind of dogfight. A missile is a sort of drone aircraft so it could apply here. One big advantage of a missile is they move extremely quickly and would be almost impossible to defend against. Additionally, the high speeds of a missile mean you can use its kinetic energy to help penetrate enemy walls to detonate inside rather than out. <http://hypertextbook.com/facts/1999/SeanManning.shtml> cites missile speeds of 860 m/s and higher, but a crude missile made in a few days by some random nerds would likely have a lower velocity. Still, the low air density and gravity on Mars mean you can get very good results with lower power. Depending on resources available, it could be feasible to create multiple missiles and target every building in the enemy facility at once. With fewer missiles (or the prospect of a long development/fabrication time per missile), you'd want to be strategic about your initial targets. The specifics would depend on the actual configuration and logistics of the enemy base, but in general the priority is preventing them from counter-attacking. Unless you have access to extremely high-yield explosives, you're not likely to kill all of them quickly. So you'd want to destroy things like their life support and let them freeze to death or suffocate rather than attacking them directly. The scientists would have access to rocket fuel (they have to leave Mars somehow) and all kinds of chemicals that that could be used to make decent explosions. Depending on the nature of the mission, they might have premade explosives for blowing holes in the local rocks. For example, mining operations. At this point, they just need to make a missile. As pointed out in other answers, air pressure and density are much lower on Mars than Earth, so missiles would need much larger fins for guidance, at which point they would begin to resemble airplanes rather than traditional missiles. Something like the Sky-Sailor might be a good start for this, but unless you really want to save fuel, you don't need aerodynamic lift. Given the abundance of rocket scientists, you could also forego guidance fins and use maneuvering thrusters like a spaceship. Cameras in the missile could be used to identify and aim for a target structure, making it virtually impossible to jam the device. Alternately, it could be remotely guided, or use some type of local GPS to detonate at a target coordinate, but those methods would be easier to jam and/or hijack the missile. Still, the war likely wouldn't last long enough for either side to develop methods for hacking the opponents' missiles, so it might be fine. One problem you'd have with explosives on Mars is the lower air density. Explosions typically work by temporarily increasing the local air pressure to extreme levels which causes damage. But a thousand-fold increase in Martian air pressure is much less of an issue than a similar increase on Earth. (This is also why explosions in the water can be much more devastating than those in air.) Unless you were able to land on the surface of a structure then detonate, concussive forces will be fairly non-lethal. However, you can still use explosives to good effect by encasing them in something hard and dense. The explosion then rips the casing apart and showers the area with high-energy fragments which work regardless of atmospheric pressure. This is the basic premise of a fragmentation grenade. A similar idea is the premise behind firearms and some types of mines: Put the explosive at one end of a tube, then pack ball bearings or similar in front of the explosive. Detonate right before you hit the target structure and you've got a shotgun blast. There are three advantages of this method over the previous method: First, you aren't wasting much energy tearing the casing apart. Second, you can focus the energy into a small angular area which in turn means A) you aren't wasting energy throwing fragments into the sky or ground and B) you'll do much more damage to the smaller area and be more likely to tear all the way through. Third, the force of the impact isn't going to be nearly as affected by the distance to the target (a spherical explosion means the fragments per square meter decrease inversely with the square of distance, while a shotgun blast is fairly collimated and the damage decreases in an almost linear fashion). An even better method, although trickier to pull of, is to detonate an explosive inside the enemy facility. This way the dense air inside propagates the energy much more efficiently, and damage to critical systems will be much higher. One method is an armor-piercing explosive. This type of explosive has a very dense nose cone designed to punch a hole in the wall of the facility, allowing the rest of the missile to follow and land inside, at which point it explodes in a normal fashion. A second method would be to detonate one explosive outside, creating a breach in the wall, then following right behind with the payload explosive that flies through the hole you left and detonates. A third, more Hollywood method, would be to covertly fly or drive a vehicle through the front door, down various corridors, and then explode. The best bet for pulling this off would probably be to land the explosive inside a crate outside the building and wait for the enemy to bring the crate inside for the night (or something similar). You might also land inside an open maintenance bay or airlock, then wait until it's been pressurized to detonate, but detection would be more likely. If you don't consider missiles to be "drones" and must use something like your picture above, all of the above can be applied to a rotorcraft with explosives. However, you're less likely to penetrate the enemy structure with momentum and would almost have to use a two-stage or covert approach to get the primary explosives inside the building. A two-stage approach would be hard though, because you'd want to detonate while internal pressure is still high, and the air venting out the initial hole would blow the rotorcraft away. Also, the size of the rotorcraft or missile is going to depend greatly on how much explosive you need to destroy the enemy compound. 5 kg might not be enough if you're trying to destroy a 100-meter dome. Here's a YouTube video of 4.5 lbs (2 kg) C4 inside a bus: <https://www.youtube.com/watch?v=0nc98hzR-tk>. You certainly wouldn't want to be in that bus, but the blast force goes down exponentially with distance, and even the fairly small bus isn't completely destroyed. On the other hand, domes would be extremely expensive, and likely much smaller than 100 meters. ]
[Question] [ **This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. Suppose we have a rocky planet (somewhere between Earth- and Super-Earth- sized) orbiting a star far enough away that it would be around Pluto's temperature if sunlight was the only heat source. If we give it a thick molten core and large amounts of volcanic activity that bring its surface temperature up to around -20°F, would it possible for humans (from Earth, not native) to live there without special gear, or would such volcanic activity render the air unbreathable? Are there any other ways significant volcanic activity would render a planet uninhabitable? [Answer] A thick molten core suggest very strongly that you are referring to a rocky planet. This also means that given standard theories on planetary formation, the composition of the mantle and crusts would also likely be earth-like. Further, we could infer that chemical composition from volcanic activity would likewise be similar. I will assume these conditions as accurate. To make a difference of 200+ degrees from volcanic activity alone, volcanism would have to be extensive and profuse in the extreme. Given that earth's volcanoes are quite toxic, with hydrogen sulfide, sulfur dioxide as well as a number of other poisons in lesser concentration, the atmosphere would certainly be quite toxic to typical earth life. The large amounts of CO2 would also be toxic to animals. To raise the temperature due to large greenhouse effect implies other problems. Either very thick atmospheres, large GHG concentrations in the atmosphere or a combination. A thick atmosphere has a problem -- high pressure alone will cause lung failure due to the extra pumping effort, though there would be other problems as well. High GHG concentrations from volcanism would also be toxic. So, humans are not going to live on this planet under open-air conditions. --- You can make a planet 200 degrees hotter than would be expected from the solar heat balance. * Put it in orbit around a Large gas giant and allow heating via tidal /electromagnet forces. You will probably be tidal-locked though * Have an extensive high tech civilization that uses lots of fusion power. It will take a lot, but the civilization could start out with enclosed cities and gradually heat up the planet as they eventually use all of the planets surface * Intentional heating via solar power satellites or such like. In theory, you could get the heat from the planet interior, in practice this is a lot harder than you might think unless the planet has a much thinner crust than the earth, but if the planet had a much thinner crust, the natural rate of heat migration from the interior could already be much higher than on Earth. --- **Supporting case - did not notice the hard-science tag originally** Just depending on volcanism for the additional heating, how much would you really need. Consider the [earth energy balance](https://en.wikipedia.org/wiki/Earth%27s_energy_budget) Geothermal heat accounts for 47 TW of heat, whereas solar heating is 173,000 TW. As you stated, this alternate earth receives effectively no solar heating at 40 AU (Pluto's orbit) you only get 1/1600 fraction of the solar heating, i.e., 173,000 / 1600 = 108 TW. Now, -20F is a good bit cooler than the earth, but if you ignore the natural greenhouse effect, the earth would actually about -18 C / 0 F. Hard to say would the greenhouse effect would be on your planet, but to be conservative, lets assume that it would also be about 60 F (unlikely since this is proportionally higher and the solar flux for Pluto is much lower). So, we are shooting for a natural black-body temperature due to solar heat balance of -80F. To maintain this lower temperature, the necessary heat is about 49.5% of the earth's heating ((459 - 80) / (459))\*\*4 -- comparing -80F and 0F using the Rankine scale and remembering the 4th power rule of [Stefan–Boltzmann black-body radiation](https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law) So we reach the conclusion that the total geothermal heating will have to be 85,500 TW. This is over 1800 times that of our earth. The only reasonable assumption is that volcanism will be indeed be massive likely 1000+ times as much as on earth. There are [several gases of serious concern coming from volcanoes.](http://volcanoes.usgs.gov/hazards/gas/) I would worry most about sulfur dioxide. SO2 is indeed toxic, but the real problem is that is usually converted to sulfuric acid that falls as rain. Soil PH would be total ruined with rain being 1000 times as acidic as ours. The large ash clouds and lava flows would also certainly be devastating. Read up on up super volcanoes and realize that these would be a common problem in this environment. The [Toba catastrophe theory](https://en.wikipedia.org/wiki/Toba_catastrophe_theory) also makes interesting reading. Even CO2 coming from a volcano can be toxic by the simple expedient of displacing oxygen. To achieve this massive level inner core heat flow, the crust will necessarily be very thin. Earthquakes will be common and quite destructive. Earthquakes are not usually harmful if humans are living in a natural open-air environment. Collapsing buildings, bridges, pipelines, dams, industrial facilities are usually the cause of death and injuries in an earthquake. Given a temperature of -20 F, buildings will be necessary for habitation, greenhouses, etc. so earthquakes will be a survival factor too. Note that the large volcanism effects make the greenhouse warming contribution essentially impossible to model -- at least without a great deal of effort. I think it is clear that the effects are so large that it is not necessary to know this in detail to know that we have a dead or at least extremely harsh living conditions on this volcanic earth. [Answer] **No, because there wouldn't be enough plants.** Free oxygen doesn't tend to form naturally. O2 is a fairly high enthalpy molecule compared to various oxides, which is why things burn well in a high oxygen atmosphere. On Earth, billions of years of life have served to produce lots of oxygen by sequestering the carbon out of CO2 and into biomass. This oxygenation of the atmosphere would not have occurred without life to drive it. Atmospheric oxygen allowed for the evolution of aerobic organisms, a prime example of which is *homo sapiens sapiens*. On a volcanic ice world, even if there are bands with survivable temperatures, there probably aren't many plants, or even large colonies of primitive photosynthesizers like cyanobacteria. Most of the world will be bitterly cold and the warmer bits (near the volcanoes) will be constantly hit by ash and lava flows. This would mean little to no oxygen, particularly as a volcanic world is likely to be quite young. Instead, you'd end up with lots of gasses like CO2 in the atmosphere, which are toxic to breathe in large quantities. (Plus, you'd suffocate without oxygen.) [Answer] I wonder how long such a planet would stay warm, before the internal heat was lost? [OK, sounds plausible](https://www.wikipedia.org/wiki/Earth%27s_internal_heat_budget) that a super-earth would retain significant heat, but the ground would be cold as significant heat is only lost via vulcanism. I suppose a super-caldera could provide an extended area over a mantle plume that's warmed to comfortable temperatures, but you still have no air. How about an underground chamber on a grand scale, like a dome the size of a nation, warmed from below and holding air? ![planets](https://i.stack.imgur.com/18nkC.png) It [could be](https://www.wikipedia.org/wiki/Super-Earth#Density_and_bulk_composition) a water-world, and a sea-sized sub-ice melt in the manner of Lake Vostok could be, say, a hundred miles down. Shore up the dome with carbon nanocomposite and remove the water, and have some mechanisms for regulating the heat buildup via venting through a bypass. Make it the size and shape of New Zealand. The referenced article mentions undifferentiated interiors, which sounds very intriguing for a story as a nugget of water-ice could be in a matrix of stone, for example; but it doesn't make sense how that can be the case with mantle convection or (if not) melting. ]
[Question] [ Mars' gravity is 38% of that of Earth's. Supposing a human born and raised on a Mars colony traveled to earth later in their life, would they be able to survive the increased gravity? ``` For example, I would weigh 63 pounds on Mars, and would land on Earth weighing 166 pounds. ``` What physiological effects could be expected? If one could not survive, would it be possible through intensive care? ### Some things to consider: 1. Side effects - for example, would one's bones, due to being much thinner, break easily? Would there be respiratory troubles? I suppose there is only speculation in a lot of this as it's never happened. 2. Length of time to full recovery. Obviously, given one survives, the body would eventually adjust, bones thicken, etc. What sort of estimate could one give on how long it would take to adjust and become "normal" on this increased gravity? [Answer] You could always simply lie down. Jokes aside, the answer is that there would be quite a few issues. Your spine would not be used to being so compressed. [This is a problem](http://en.wikipedia.org/wiki/Effect_of_spaceflight_on_the_human_body) with astronauts returning home from extended stays in space. There are two key issues: 1. **[Spaceflight osteopenia:](http://en.wikipedia.org/wiki/Spaceflight_osteopenia)** In microgravity, there is less stress on the bones in the body. Therefore, they become less dense. Back on Earth, the bones must support weight. However, they are too weak, and it is extremely hard for astronauts to walk again after long stays in space because of this loss. On Mars, a human would have low bone density; they wouldn't be able to stay upright *without much effort* on Earth. To counteract this, Wikipedia gives the following: > > Increasing dietary calcium and vitamin D is a standard countermeasure for osteoporosis. Clay is reportedly used by NASA for retaining calcium. > > > You'd need a *lot* of calcium and vitamin D, but it's possible you could adapt to life on Earth. 2. **[Muscle Atrophy:](http://en.wikipedia.org/wiki/Muscle_atrophy)** Something similar happens to muscles. In space, they aren't used to maintaining effort by keeping the body up. Therefore, they become weak. This would also be a problem for someone going from Mars to Earth. Their muscles would only be useful in relatively weak gravity. Wikipedia suggests the following: > > One important rehabilitation tool for muscle atrophy includes the use of functional electrical stimulation to stimulate the muscles. This has seen a large amount of success in the rehabilitation of paraplegic patients. > > > Or you could go the low-tech way and simply work out for a while. It would take quite some time, but it would work. I think it's safe to say that you would survive, but it would take a lot of effort for you to function normally on Earth. [Answer] While just going straight from Mars to Earth would be problematic for a native of mars, there is a bigger problem. Currently it would be about 150 day journey to travel between the two planets. if it was all the way in micro-gravity even earthlings will have issues on Mars, though not quite as bad. So the important thing would be for transportation ships to be built with the ability to have a gravity ring, or even a couple. And everyone would need to exercise and spend some minimum amount of time in these. It would be even more important for the Mars return to slowly try to acclimate themselves to a heavier gravity, if there was a couple of rings and they could take time working themselves up to full earth they would have several months to adjust before they ever landed on earth. There is a very good chance that they might need most of that time and be pretty pro-active if they don't want to feel like they're being crushed. Of course the diet on ship should help with the nutrients (calcium, etc) to encourage healthy development. ]
[Question] [ The setting: A planet with two main landmasses, each one's center located more or less at each pole of the planet. Liquid water ocean in between them, wrapping fully, if not directly (due to the non-symmetrical nature of landmasses on either side), around the equatorial region of the planet. The planet has a moon **(EDIT) or co-orbital planet** that is of appropriate size and distance to exert a significant tidal pull on the ocean, and the ocean is of adequate depth and water volume to show tidal effects. **Is there any variation of the details** (oceans bigger or smaller, moon closer or farther, etc) **of this generally vague setup that allows for tidal forces to get the ocean moving in a river-like flow around the equatorial area of the planet?** (as opposed to some misunderstanding I have of Tidal forces making this entirely implausible) **EDIT** To provide some background of where I got the idea for this question: I've heard about tides in certain places on Earth being exaggerated due to resonance and oscillation matching the shapes and sizes of bordering land. From there, it seemed to me that if the tide frequency (orbital frequency of the moon) also happened to resonate with the size/shape of the ring/ocean it would flow something like water in a cup when you swirl it around, just on a planetary scale. (also, I understand that this would likely drag the two bodies in to tidal lock, eventually, so the exact time-scales need not be too long, just "long enough" for a story) [Answer] # Your planet is a linear motor This is something I proposed in some detail in [this answer](https://worldbuilding.stackexchange.com/questions/123419/how-can-a-remote-planet-with-little-to-no-sunlight-have-high-wind-speeds/124431#124431). Your oceans are driven by a [magnetohydrodynamic drive](https://en.wikipedia.org/wiki/Magnetohydrodynamic_drive) to constantly circulates the narrowly bounded ocean around the planet. This is how it works: * Two powerful magnetic fields; one from your planet (an iron core like on Earth) and one external (perhaps an Earth-like planet is circling a Jupiter-like planet). * To turn the ocean into a linear motor, you need a [magnetic field and current flow](https://en.wikipedia.org/wiki/Linear_motor) and they have to be not in the same direction as each other. * Let the magnetic field generated by the planet be the same as the Earth's (though, perhaps stronger). * Let the magnetic field generated by the 'Jupiter' be ever changing as the planet rotates. Thus, by [Lenz's law](https://en.wikipedia.org/wiki/Lenz%27s_law) you will induce a current in the ocean. * Now, with a magnetic field and current, you have induced motion rom the [Lorentz force](https://en.wikipedia.org/wiki/Lorentz_force). So this is what you need on your planet: * A continental setup as you describe. Two large circumpolar continents, and between them a relatively narrow ocean. * The ocean must be very salty to induce a good current. * The planet must have its own, very strong magnetic field. * The object the planet orbits (the [primary](https://en.wikipedia.org/wiki/Primary_(astronomy))) must have its own, very strong magnetic field. * If the planet orbits its primary is a perfect equatorial orbit, then the current and magnetic vectors will only differ by the [magnetic declination](https://en.wikipedia.org/wiki/Magnetic_declination) of the magnetic field on the planet. This is the angle between the axis of rotation and the axis of the magnetic field's dipole. Earth's magnetic declination is about 11 degrees, that is too small. * Therefore, the combination of magnetic declination and [orbital inclination](https://en.wikipedia.org/wiki/Orbital_inclination) between the planet and its primary to be something like 90 degrees. Adding some eccentricity would probably help matters, too. ### Conclusion Get all the characteristics just right, and you now have a linear motor. The energy comes from two sources. The planets magnetic field takes thermal and kinetic energy from the planetary core to help drive the oceans. The other energy sources is the kinetic and rotational energy of the planet relative to the primary and the primary's interal thermal and kinetic energy through its magnetic field. Ultimately, you have to consider that moving an ocean for a billion years takes a lot of energy, so it might not be possible for this planet to exist in such a condition for a long time, from a hard-science perspective. But it could exist for some time, so that is good enough for a good story! [Answer] Just possibly, maybe, but not easily. Ocean movement due to tides is [mostly back-and-forth with mixing.](http://oceanmotion.org/html/background/tides-ocean.htm) It can be very complicated around barriers and in estuaries and the entrance to bays and places like that. In the deep ocean near the surface the motion of any given bit of water is more-or-less circular during a cycle of the tides. Don't forget that the pulls involved in producing tides are cyclic, and pull "back" as often as "forward." So which way do you expect the sustained flow to be? Ocean currents are [driven](https://oceanexplorer.noaa.gov/facts/currents.html) by wind, salinity differences, temperature differences, and gravity. And occasionally earthquakes. This is how you can sustain flow in a direction. For example, consider where a fresh water river enters the ocean. This introduces non-salty water at a different temperature. This will tend to flow steadily in a direction determined by the various surrounding details. Or consider the existence of trade winds that blow in one direction much more of the time than any other. This will tend to drive surface water in that direction, returning it along some other flow path. So the usual naturally occurring situation will not mean tides produce a sustained flow in one direction around the equator. You would have to construct something extremely contrived. Imagine, for example, a sequence of bays just angled perfectly to produce very high tides such that water flows up and over some barrier on one side. But the shape of the ocean shore on the other side did not produce such high tides. You'd need to "focus" the shape of the bay on one side, say the west side, to amplify the tides. Then at only the high point of the tide it spills over the edge, and only in one direction. You'd need a whole series of such all around the equator to produce anything like a sustained flow. Note that they would not need to be above the surface of the ocean, only close enough to the surface to focus the tidal flow in this manner. [![enter image description here](https://i.stack.imgur.com/L4UYL.png)](https://i.stack.imgur.com/L4UYL.png) Maybe a little like that. From one side, each terrace tends to collect the flow inward to the center. From the other it tends to disperse it. So the first half of the daily tide cycle gets pushed in, and the second half gets pushed out. If you had a series of these all the way around the equator, the water would tend to flow west-to-east in the middle, and east-to-west along the top and bottom of the terrace. Note that to work they would have to be many 100 km long, and there would have to be a lot of them, probably all the way around the equator. Plus they'd have to be spaced just the right distance apart. So a wild idea of how that might have happened. Maybe many centuries ago the water level was much lower. An ice age perhaps? And the land at the equator was above the ocean. And the people who lived there then did a lot of terracing and shaped the land all the way around the equator to produce good growing. Maybe something like rice that wants to grow in water some of the time? Maybe they faced all these terraces towards the east so they got the morning sun. And the shape of all these artificially constructed hills is just perfect to focus the tides. [Answer] The ocean will already flow that way due to existing effects caused by the planet's rotation. It's doesn't need a moon and tidal effects to do it. See, for example, the [Antarctic Circumpolar Current](https://en.wikipedia.org/wiki/Antarctic_Circumpolar_Current) which does exactly what you want, albeit at a lower latitude. ]
[Question] [ **I want to know if this is physically possible.** So at first I thought I was nuts. Then I started reading about [Hill Radii](https://en.wikipedia.org/wiki/Hill_sphere), and googled left and right. Turns out a Hill Sphere is the region around an astronomical body where it is dominant in regards to attracting satellites. The Sun has a Hill "Sphere" of sorts, but close enough to Earth, the Earth's Hill Sphere is dominant. $r\_H = a(1-e)\sqrt[\leftroot{-2}\uproot{2}3]{\frac{m}{3M}}$ which simplifies to $a\sqrt[\leftroot{-2}\uproot{2}3]{\frac{m}{3M}}$ for circular orbits, where e is eccentricity, a is the semimajor axis of the smaller object's orbit around the larger body, and m and M are the masses of the smaller and the larger object, respectively. It occurs to me that as M grows larger and larger, the area where the gravitation of the mass-m orbiter dominates over the larger M shrinks more and more, and the degree to which planets perturb their neighbors shrinks and shrinks. So here's the idea: * One supermassive black hole (think > 100,000 $M\_{\odot}$) * Orbiting that, place One (1) [coorbital-ring](https://ui.adsabs.harvard.edu//#abs/1988A&A...205..309S/abstract) system of 7+ sun-like stars, a safe distance from the black hole, in a [stupidly stable](http://adsabs.harvard.edu/abs/2010CeMDA.107..487S) orbit. * Farther out, a whole coterie of dozens (hundreds?) of worlds orbiting within say 0.1 AU of each other, their Hill Radii safely shrunk to the point where they barely interfere with each other. Potential downsides: * Planets may get tidally locked, and may get a bit, uh, unspherical. * Despite doing the math, I still have a hard time believing that the planets would not perturb each other. Potential upsides: * At really ridiculously low Hill Radii, you could (have not done the math) have coorbiting planets, and have them almost touching. A Niven ring made out of planets. * If the perturbations really bother you, just add more suns to the Sun-ring, and push the Goldilocks zone out to multiple AU. *But this could never just happen naturally!* Well, duh. [Answer] Only dozens of habitable planets in one solar system, eh? Well, you're thinking small. The work for a [solar system with one million Earths](https://planetplanet.net/2018/06/01/the-million-earth-solar-system/) has already been done by astrophysicist Sean Raymond. His model, like the one postulated in his question, is centred on a supermassive black hole. > > > > > > Let’s start with a supermassive black hole, like in the Black Hole Ultimate Solar System. It’s 1 million times the Sun’s mass. A > > behemoth! > > > > > > > > > Now let’s see what rings of planets we can make. As we saw in the > Ultimate Engineered Solar System, a ring of 42 Earths orbiting a > Sun-like star is stable. > > > Sean Raymond's One Million Earths model solar system also considers the role of the Hills radius. > > > > > > The requirements for a stable rings of planets are simple (technical details here and here): > > > > > > > > > The planets on a given ring must all have the same mass, > There must be at least 7 of them, and > They must be evenly spaced along a circular orbit and separated by at least 12 Hill radii. (The Hill radius is the distance inside which > a planet’s gravity dominates over its star’s.) > > > Around a supermassive black hole (of 1 million Sun masses) the Hill > radius shrinks to 1/100th of its value around the Sun. That means > that 100 times more planets can fit on the same ring around a black > hole! > > > Persons seeking more information about the One Million Earth solar system should refer to his website. However, his basic model can be detailed as follows: -- > > Let’s start simple. In the Black Hole Solar System I replaced the Sun with a Sun+black hole system. Let’s do the same thing again. Of course, in the Black Hole Solar System I used a Solar-mass black hole and here we will use a million Solar-mass black hole. But it doesn’t make all that much difference. > > > A supermassive black hole is not very big. Its event horizon (or > Schwartzschild radius) — the distance inside which light can’t escape > — is only 2% of the Earth-Sun distance (that is, 0.02 AU, or 3 million > km). That’s about 4 times bigger than the Sun. The innermost stable > circular orbit around the black hole is three times that distance, > about 0.06 AU. To avoid anything too crazy, I’m going to put a single > Sun three times farther out, at 0.2 AU. > > > In this system the central black hole+star weigh 1 million Suns (well, > 1,000,001 to be annoyingly precise). But they produce the same amount > of energy as one Sun. That means that the habitable zone is at the > same place as for the Sun. > > > Let’s break out the planets. If we mega-pack rings, with alternating > rings on retrograde orbits, we can fit up to 689 rings in the > habitable zone. Each ring can hold up to 4154 planets. That makes > for a maximum of 2.86 million planets! I’m going to be a cautious (I > know, that is not my usual m.o.) and space things out more. Let’s use > 400 rings with 2500 planets each. That’s a million Earths in the > habitable zone! > > > In conclusion, solar systems with dozens and all the way to around one million habitable planets does seem to be physical plausible. The probability this could happen in nature is presumably remarkably low. This doesn't necessarily prevent a sufficiently advanced technological civilization building its own solar system with a suitable plenitude of habitable planets. This is much more achievable if the primary barycentre is a supermassibe black hole. [Answer] While I clearly am not going to make nearly as useful a post as that above, here is something to consider as a heuristic for most sci fi authors in general. If you are writing anything not hard sci fi, then why not play around with questionable possibility? Strictly possible is likely a moving target (ask Burgess) but some of the better sci fi pushes those boundaries and no one fault Clark because Jupiter can become a star on its own. If something is inspiring, why not ride that wave? Especially if you've yet to publish, just getting words on paper is a good thing. Just saying ]
[Question] [ Previous parts here: 1. [Creating a scientifically semi-valid super-soldier, part 1: Skeleton](https://worldbuilding.stackexchange.com/questions/106292/creating-a-scientifically-semi-valid-super-soldier-part-1-skeleton) 2. [Creating a scientifically semi-valid super-soldier, part 2: nervous system](https://worldbuilding.stackexchange.com/questions/107365/creating-a-scientifically-semi-valid-super-soldier-part-2-nervous-system) 3. [Creating a scientifically semi-valid super-soldier, part 3: Physical shock resistance](https://worldbuilding.stackexchange.com/questions/107635/creating-a-scientifically-semi-valid-super-soldier-part-3-physical-shock-resis) 4. [Creating a scientifically semi-valid super-soldier, part 4: respiratory system](https://worldbuilding.stackexchange.com/questions/108558/creating-a-scientifically-semi-valid-super-soldier-part-4-respiratory-system) 5. [Creating a scientifically semi-valid super-soldier, part 5: Heart and circulatory system](https://worldbuilding.stackexchange.com/questions/109503/creating-a-scientifically-semi-valid-super-soldier-part-5-heart-and-circulator) 6. [Creating a scientifically semi-valid super-soldier, part 6: Radiation protection](https://worldbuilding.stackexchange.com/questions/111275/creating-a-scientifically-semi-valid-super-soldier-part-6-radiation-protection) 7. [Creating a scientifically semi-valid super-soldier, part 7: Hearing](https://worldbuilding.stackexchange.com/questions/112777/creating-a-scientifically-semi-valid-super-soldier-part-7-hearing) In just about any profession communication is important. For a soldier this is even more important, as both processing and signalling information can mean life or death for nearby allies and enemies. So when designing a super-soldier from the ground up you want to pay special attention to how they communicate. Some restrictions for this design: Each communication method needs to be biologically buildable, repairable and maintainable without external help from a workshop (so no mechanical implants unless the body can build them). Also it needs to fit on a creature that looks as much human as possible. Small edit: as a future super-soldier, space-based combat could happen and communication in space would be handy in case of failure of the given equipment. There are many many types of communication possible, here's a few I had thought off with varying chances of success: * The face. Humans use it for communicating emotions, with some extra musculature and other tissues the soldier can communicate other things as well during combat. Set facial expressions can signal the health status of the soldier, and by changing some expressions in a specific way soldiers could even communicate with eachother (instead of sign-language, face-language). The disadvantage is that soldiers could wear helmets that prevent reading the face, or enemies might see what a soldier is communicating by looking at their face. *Possible interception*: Anyone who can discern your features is able to see the communication. Binoculars and other vision enhancing equipment make it easier. Can only intercept when lookin at the front of the face. * The hands (and arms). Sign language exists, use it. Unlike facial expressions the hands can communicate even when covered by armored gloves and sleeves and are much better visible from a distance. Disadvantage is that you need to empty your hands before communicating. *Possible interception*: Anyone capable of discerning the exact movement of your hands is able to read it, vision enhancing equipment will help intercept messages. Can intercept from the front and side as long as nothing blocks the vision of the hands. * Bioluminescence. <https://en.wikipedia.org/wiki/Bioluminescence>. This gives you a better range and better visibility at night. It also relies on visible skin. Cuttlefish (<https://en.wikipedia.org/wiki/Cuttlefish>) can control the lights on their body to a great degree and create immensely complex patterns, and actually already use this to communicate. Such patterns of shape and colour could signal immense amount of data to friendly soldiers in quick succession, allowing for short bursts of silent communication to reduce the chance of interception or discovery because of using it. Again a disadvantage is the fact that some skin needs to be visible. *Possible interception*: Vision, possibly with visiual enhancing equipment or if there's less light interference (like during the night). Depending on the positioning this can be intercepted only by being straight in front (for something closer to a laser or encased by something) or from the front and sides if it's a light on the surface of the skin. * Camouflage. Cuttlefish again are capable of immensely complex patterns on their skin, even without light. Such patterns could, possibly in combination with all the other methods, signal large amounts of information to other soldiers nearby. Another advantage would be the ability to camouflage exposed skin on the fly. A disadvantage: You have to have exposed (or at least visible) skin to do this, which restricts what kind of armor you might be able to wear and the amount of protection it gives. *possible interception*: When seen from the front (of the surface area) it can be read by anyone, vision enhancing equipment increases the range. * Sound: <https://en.wikipedia.org/wiki/Parasaurolophus>. The ParaSaurolophus (probably) used a crest on it's head to produce low soundwaves that carried far for communication. Similar things might be located on the body of the humanoid. Question is how to put them on the body without making it look alien. *possible interception*: Anyone within a certain radius. The range from the front will be longer than the range from the back, but in essence it can be intercepted from any direction. As example here's some ways directional microphones could help intercept at range: <https://scienceprog.com/long-range-directional-microphones-myth-and-reality/> * Sound: Voice. I'm not sure, but perhaps multiple vocal cords could be installed for a variety of sounds, from high frequency to low frequency, to improve the range of communications available. A squadleader is definitely going to find a deep, carrying voice with a lot of range useful for keeping track of his soldiers and giving orders. Disadvantage is ofcourse that enemies might hear it too. *Possible interception*: Anyone within hearing range. * Electric potential. A close-range communication, similar to an electric eel the soldier could produce an electric potential on it's skin to communicate with (it could also be used to communicate with electronics). To communicate with a fellow soldier they would need to touch eachother. Armor could possibly have conductive area's to allow touch without removing the armor. The pulses, frequency etc could all be varied to transfer types of information quickly.*Possible interception*: You'll have to be able to register an electric potential at range with enough detail to identify individual nerve input or you'll have to be touching the target you want to intercept the message from. Neither seems very likely. * Biological radio (normal radio applications, WIFI, short-ranged Bluetooth). I'm really interested in the potential of a biological radio. Would it be possible to build one? Would it be too easy to find a soldier using a bio-radio on a battlefield using electronics? What would be the range of such a bio-radio? Could the soldier change the range in case it might be intercepted? Could fellow soldiers even receive the messages with their own bio-radio? *Possible interception*: We can currently already intercept radio, and use a variety of methods to make the message unreadable. To prevent interception the users would need to restrict themselves to a limited set of predetermined short signals. Possibly with one signal that will shift the meaning of each individual signal should the enemy discover what certain signals mean, all predetermined prior to the battle. * Pheremones. Many animals use it to communicate, and it has the advantage that you can leave it behind for other soldiers to find later. Disadvantage is that it means anyone with a good nose can find the pheremones and the soldier excreting it, it takes a while for the communication to get through to everyone and wind could prevent communication in some directions. *possible interception*: Anyone who comes along and can smell the pheromones. More so than with biological radio, the users would determine the meaning of each pheromone prior to a battle so the enemy only knows there's a signal, but not what it means. That was more than a few I thought off. Does anyone have a good idea about such systems? Or does anyone have a better method of communication they can think off? [Answer] At first I would try to avoid everything long range, simply because every enemy could use that to locate your soldier and even "read" their communication. So Bioluminescence and Radio is definetly a bad idea, since it would inform every enemy about the presence of your soilders and how far away they are. Edit after request: Why do we use radio but it is a bad idea for a hunter species. At first, radio is already a big problem today and was in past wars. One of the biggest examples is "The Bomb" from Alan Touring. "The bomb" was a huge calculating machine, in WW2, that was used to calculate the enigma codes, which was used to encode the German communication, including radio communication. After Allies got those codes, they knew German Actions in advance and is assumed, that this shoretened the war for about 1 til 2 years. Since then the biggest arms races between militarries has been, over encoding and decoding communication lines, be it radio or other ways and often compelte concepts or technologies are thrown out because the enemy found a way to crack all their encodings in an effective amount of time. And that is the problem, there is no bilogical way to effectively block out your pray/enemy, from reading at least a bit from your communication, since evolution doesn't allow big changes, which would be necessary to effectively encrypt your communication. And even if somehow you could prevent that, it is not even neccesarry for pray/enemies to encript. If you just can feel radio signals, you would know if one or even more of your soldiers are around and how close they are. Even the direction would be known. So I really wouldn't use that for a biological super-soldier. Also everything that needs the transmitter to be visible, with the exeption for close range communication, but here a simple sign and body language is enough, you don't need detailed information most of the times and long dances or other movement patterns for complex communication just takes time and may draw unneccesatty attention. Edit after request 2: Bioluminescence, the problem with every light based communication is: It warns every enemy around, that the super-soldier is around or you keep it so dim, that it doesn't bring andy advantages in comarison to body language. And especially at night, light can be seen very easy from very far away. I had in my basic education from the german military a "night seeing" lesson, where we where out in the field in the night and had to learn the different lights, that our vehicles use to identify them correcly. But also we where shown how easy light can be seen from great distance. More specific, a glowing cigarette that we could clearly see over a 4km distance. I don't think that there would be any effective way to hide any kind of light communication when it is dark and when you only use it at daylight, when you can also see gestures, what does it really add? Then the Pheremones, they have the problem that they stay for a long time, basicly allowing everyone else to know that one of your soldiers where there, where they went and gives them a certain idea of what they where comunicationg. Also it gets extremely limited by wind. Sound via voice and other noises stays the best way to communicate, that is also why basicly every animal uses it one way or another, it was simply the best way to communicate. Now which sound type is the best? I think for hunters, as soldiers are, african click languages would be a nice blueprint. They allow mid range communication via "normal" sounds, meaning sounds that we are used to, but they also can be used very closely towards enemies without alarming them, by using more clicking sounds which can't be heard over a longer distance and are way more difficult to locate. Cats also use clicking sounds when they are focused on a "target". [An African, using a clicking language, the clicking would be more and the "normal" sounds would be less when close to a target](https://www.youtube.com/watch?v=W6WO5XabD-s) [Two cats communication via clicking sounds while focused](https://www.youtube.com/watch?v=FkdJ7yOdBUA) [Answer] Two things come to mind: 1) Extrasensory perception - super soldiers somehow evolved a form of telepathy for communication. We can put sensors on our heads to read the electromagnetic fields emanating from our minds but are as yet unable to read someone's thoughts. [![enter image description here](https://i.stack.imgur.com/H8ZoX.jpg)](https://i.stack.imgur.com/H8ZoX.jpg) If those same fields were able to be directed/focused toward another individual it would reduce the amount of power required and also reduce detection. 2) The super-soldiers develop super high frequency vocal emissions and hearing to match. Or, their eyes develop receptors to see the infrared or ultraviolet EM spectrum. If a part of their body could emit the corresponding spectrum they could have a light based way to communicate that is not detectable to people who aren't using special equipment. Currently, many military forces use infrared emitters on their weapons for sighting which can only be seen with night vision goggles. Even though the technology is quite widely available now it is still used. [Answer] How much info can you encode in adn? Inject cells with the information in the receiver's corresponding organ, a la wasp planting larvae or genetically created organ. bam, ton of info that can't get inferred unless they cut your reservoir to take a sample. can be prepared in advance and the delivery takes an instant. edit: seems like this is akin to asking for the best hammer. There are jewejer's lil hammers and powerhammers. Depends on the distance, energy constraints and the confidentiality of the info being transmitted. Sometimes you only need "good enough". [Answer] For short, visual range, we could base communication off of Semaphore. Semaphore is basically using signs to communicate letters to someone far away. Ships back in the ages of wood, sails, and broadsides, used flags to communicate words, so a navy could move and attack in unison. So on or near the helmet, you could have a small display of various signs, each meaning either a word or an action. As a general rule, the more urgent a sign, the more simple it should be. (Such as solid yellow for "caution"). You could even have a speech-to-sign function in your helmet. This works best as backup or signal blackout communication, and is not reliable for anything but short range communication. [Answer] Crystal radio receivers can be built with hand tools by children; [(description)](https://www.electronics-notes.com/articles/radio/radio-receivers/how-does-crystal-radio-work.php) Grow the diode yourself out of 'mineral supplements'. Instead of headphones, plug directly into nervous system. Note that these work on AMPLITUDE modulated signals only, not frequency modulated or digital; and I don't know the upper frequency limit. But merely being able to receive, say, weather reports could be useful. Or "The enemy is attacking to the right of Hill 282!" Or "Execute Plan 4b in ten seconds." Another that isn't exactly or entirely communications is sensing magnetic fields (changes) via induction - this allows tapping of telephone wires without having to interrupt or disturb the circuit, though only at VERY close range (like touch). It might be possible to biologically generate similar signals, since IIRC [early microphones](https://en.wikipedia.org/wiki/Carbon_microphone) were grains of carbon that sound pressure waves squeezed (slightly) together or vacuumed (slightly) apart to change the conduction of electricity through the entire thing; carbon granules in a sealed cavity and a membrane open to sound seem entirely possible in the biological sense. Using wired communications seems unlikely in modern times, but every bit helps, right? Either of these would also facilitate no-sound no-hands radio communications (that would require extra external equipment, though). But being able to scream "Holy moley they're right in front of me!" over a radio without making an audible whisper or even moving, seems like a great improvement. Come to think of it, to improve upon bioluminescence - what use could be made of a 'slime' that would start glowing AFTER a time period? Just have it so that the light-producing reaction doesn't start until something else chemical happens, I don't know... but produced from something like a venom gland, you could smear (or write) a liquid or gel onto something else, then the soldier LEAVES, and eventually the slime would start to glow (maybe in near-infrared?). ]
[Question] [ So I have been working on a world where space has been "cracked" by some mysterious disaster which plunged the world into chaos. It is not immediately apparent - i.e. no giant glowing holes in the sky, but the world map no longer follows the rules of geometry; * The journey between two settlements may be longer one way than the other * Retracing your steps may not return you to your destination * A "pocket" that can only be reached by one specific route. i.e - travellers from the wrong direction will bypass altogether * Places that occupy the same location on the map, but are completely separate The changes are large enough that they wouldn't necessarily affect travel within a settlement, but would only become a factor over a couple of days of travel. The survivors are located in a series of villages and settlements scattered across the continent where the story takes place. Communications and trade routes are being reestablished. This is some time after the apocalypse- possibly a generation or two, so the immediate aftermath has been dealt with. There are no GPS or communications satellites, though some maps of the world world remain. My question is - how hard would it be to discover the distortions using traditional cartography? Could you definitively prove that space has been warped, taking into account survey errors, etc etc? EDIT: Typo and clarifications [Answer] Triangulation is very useful tool for navigation. Basically, you take the angle between three different landmarks and correspond that to a map. But, it relies on space being (approximately) flat such that the angle you perceive between three landmarks is unique. Here's a crude example. Imagine you see a landscape like this: [![landscape](https://i.stack.imgur.com/6HSwO.png)](https://i.stack.imgur.com/6HSwO.png) After you determine the angles between the three landmarks, you can refer to a map and play with the map to try and find the one spot where you would perceive these landmarks with this angle between each of them: [![triangulation](https://i.stack.imgur.com/0OwA2.png)](https://i.stack.imgur.com/0OwA2.png) Notice that if space is flat, then there should always be a one-to-one correspondence with the angles you perceive landmarks making to each other and places in the world. All you would need to do to prove that some sort of extra dimensional overlapping or distortion is occurring is to find a location where three landmarks all appeared to be the same angle from each other as viewed from some other distinct location. Here's a final mock-up. Notice that the new location has bent lines leading from it to represent the non-euclidean spacial relations, but the lines meet at the same angle: [![non-euclidean example](https://i.stack.imgur.com/oyoWE.png)](https://i.stack.imgur.com/oyoWE.png) ]
[Question] [ So for the story I'm writing, I'm designing is a gas dwarf with a very strong magnetic field and a planetary ring with a slightly inclined orbit. However, the rocks within the ring are very sensitive to magnetic fields. How would this affect the shape of the ring, if it is able to form at all? They would probably be ferromagnetic, since the rocks need to have a strong, permanent magnetic field. As for more details about the planet, I did make another post about it [here](https://worldbuilding.stackexchange.com/questions/44651/can-this-unique-planet-be-colonized); the rings are made up of the same moon that created the planet's "Aether" surface. [Answer] This has indeed been investigated. I found [a thesis by Daniel Jontof-Hutter (2012)](https://www.astro.umd.edu/people/Theses/2012Jontoff.pdf) that did a stability analysis of particles in rings orbiting, among other bodies, Saturn. One important quantity he studied was the ratio of electric force to gravity, $L\_\*$. When $L\_\*\gg1$, the electric force dominated (the "Lorentz regime"), while when $L\_\*\ll1$, the gravitational force dominated. The exact value of $L\_\*$ determines whether the rings will be stable or not; the presence of the electromagnetic field can lead to instabilities. There's not an analytical stability condition, unfortunately, so we have to look at numerical simulations to answer your question in full. ## Technical details Jontof-Hutter considered the [Lorentz force](https://en.wikipedia.org/wiki/Lorentz_force) in the case of a rotating magnetic field: $$\vec{F\_B}=\frac{q}{c}\left(\vec{v}-\vec{\Omega\_p}\times\vec{r}\right)\times\vec{B}$$ where $q$ is the charge of the particle, $c$ is the speed of light, $\vec{r}$ and $\vec{v}$ are the particle's position and velocity, $\vec{\Omega\_p}$ is the planet's spin vector and $\vec{B}$ is the magnetic field. The electric component of $\vec{F\_B}$ is $q\vec{E}$, where $\vec{E}$ is the electric field: $$\vec{E}=-\frac{1}{c}\left(\vec{\Omega}\times\vec{r}\right)\times\vec{B}$$ $\vec{B}$ is given, for a dipolar magnetic field, as $$\vec{B}=\frac{-g\_{10}R\_p^3}{r^3}\vec{z}$$ where $R\_p$ is the radius of the planet, $r=|\vec{r}|$, and $g\_{10}=|\vec{B}(r=R\_p)|$. Therefore1, $$L\_\*=\frac{qg\_{10}R\_p^3\Omega\_p}{GM\_pmc}$$ where the planet's mass is $M\_p$ and the particle's mass is $m$. Let's go to a picture. 16,000 grains were simulated, at many different values of $\vec{r}$ and $L\_\*$. Here are the results: [![Chart of numerical results for particle stability](https://i.stack.imgur.com/Nsuw8.png)](https://i.stack.imgur.com/Nsuw8.png) The darker the dots, the more unstable the configuration. Here's an annotated version of the diagram: [![Annotated version of stability chart](https://i.stack.imgur.com/jDarg.png)](https://i.stack.imgur.com/jDarg.png) $R\_{\text{syn}}$ is the radius at which an orbit is synchronous with the planet's rotation. Essentially, at small $L\_\*$, the rings should be stable at almost all radii. In regimes where $0.5<L\_\*<10$, there are fewer stable regions, and you can't have large stable rings. This does become less of a problem with large $L\_\*$, but there are still instabilities, more than for $L\_\*\ll1$. --- 1If you want, you can view this as $$L\_\*\propto\frac{\Omega\_p}{Q\bar{\rho}\_p}$$ where $\bar{\rho}\_p$ is the mean density of the planet, and $Q$ - notation I've absolutely butchered - is the mass-to-charge ratio of the particle, $m/q$. [Answer] The magnetic field is likely not going to be uniform in the space orbited by the ring particles. This means that any variation of the magnetic field will result in an induced current into the particle. A flowing current means, by Ohm effect, an increase of the temperature of the particle that, being in very low pressure, will result in an increased evaporation rate. If the evaporation is "slow" the particle will slowly dissolve in space, if it is "fast" the evaporation will propell the particle somewhere. In both cases the rings system is not going to last for long. ]
[Question] [ So for the purposes of this question, the following items are already determined by our world: * The humans and human society are in very beginning of an Industrial Revolution almost identical to our own on an Earth identical to our own, meaning they are technologically and socially on par with Western culture in 1760-1800. * Animals have developed human-level intelligence. Direct quote from Wikipedia: > > Human intelligence is the intellectual capacity of humans, which is characterized by perception, consciousness, self-awareness, and volition. Through their intelligence, humans possess the cognitive abilities to learn, form concepts, understand, apply logic, and reason, including the capacities to recognize patterns, comprehend ideas, plan, problem solve, make decisions, retaining, and use language to communicate. Intelligence enables humans to experience and think. > > > * Not all animals have become intelligent. Firstly, it has only affected mammals. No lizards, no birds, no bugs, etc. * Secondly, it has not affected any animals who were genetically manipulated by humans and domesticated. So cows, pig, sheep, "food animals" are still dumb. Same for cats and dogs, they are still our companions but not intelligent. * Thirdly, even among "wild mammals" the newly intelligent animals are a small percentage. Say about 10-20% of current animals' populations were affected. So we aren't talking about hundreds of bears suddenly becoming human smart, but maybe a few dozen. * For purposes of the question, I'd like to focus in on Eastern U.S. and Western European species of wild mammal, such as bears, wolves, rodents (squirrels, rats, rabbits, mice, etc), deer/elk/etc, wild boar, and so on. * We are assuming that granting human intelligence and sentience to these animals has brought them together *mostly* peacefully, so that animals who were once predator/prey (deer and wolves for example) are now working together due to these special circumstances. * Also for the purposes of this question we will be assuming that the animals can communicate to one another. That whatever mystical, fantastical, or magical "incident" let's say, that gave them this intelligence also allowed them to "speak" to one another, whether through telepathy, or powerful perception of body language and their natural animal sounds. This telepathy or perception, however, only extends to other animals affected by the same incident and is cross-species. **How could the animals reveal their newly found intelligence to human society?** How could the animals first communicate their sentience in such a way as to convince the humans of their intelligence? Assuming that the animals are now smart enough to understand and parse together local language (English), but still lack the physiological ability to form human speech, how do they communicate? Would it be easier for them to approach as a large group or would they select a "liaison" to attempt to approach human society? Which species would be best suited for this? Would they head straight for places of government and large cities or would they drum up support from smaller villages? You don't need to answer all questions above. They are just a few examples of discussions that branch off of the main question which is in bold. Basically a discussion of what methods would work best for human-intelligent animals, who had previously been seen as wild, dumb creatures, to convince humans they are now smart enough to cause some serious problems. [Answer] I'm not sure that you'll get the Animals of Farthing Wood setup you want. [![Animals of farthing wood](https://i.stack.imgur.com/vckNJ.jpg)](https://i.stack.imgur.com/vckNJ.jpg) **Animals in the wild** First, suddenly you've got a lot of smart bears but what are they going to learn from? They're not going to see signs and suddenly understand writing. They're going to be smart but they're still going to be bears. They'll be better at making bear choices and catching their prey in smart ways and some might even start using rocks as tools. **Smart does not mean cooperation.** Humans are smart but we have a tendency to murder anyone who doesn't look like us. Why would bears be less racist(speciesist) about smart dear than we are about other smart humans? **Smart does not mean peace or fast development of tools** Smart humans went 40,000 years in Australia without developing the bow and arrow and they fought wars with each other. **Which animals are most likely to learn english and try to communicate with humans then?** **Rats.** Rats live in close proximity to humans. They outnumber us so there's going to be hundreds of millions of smart rats so lots of chances. There's going to be lots of little smart ratlings hearing english as they grow up with the best chance of learning language and understanding. If they're curious they're the most likely to be able to peek into classrooms or watch humans talking, singing, dancing or to learn anything else from humans. They're going to be scared, particularly when they learn how many rat-related expressions we have. They won't want to be "trapped like a rat" but with tends of millions of young curious rats eventually some are going to try their luck at communicating. **Reception** Most will be ignored or people won't understand and will just freak out at the rat but sooner or later someone is going to start talking about "The Pet Rat I Just Caught Which Can Totally Count and Do Tricks" and from there reports of things like a rat pushing pebbles into patterns that look like writing from signs or similar are going to start spreading until people will start looking into it seriously. 1800's era it a bit sketchy, humans were still classifying other humans as fauna at that time so rats aren't likely to get the vote but some of the gentlement scientists are going to figure out that they're pretty bright for animals. **Reaction** The rats won't need to "head" for places of government, they're already there. Now the question is, how much would humans freak out at the idea. I'm thinking a major rat-genocide from angry and afraid humans with smart rats poisoning humans in retaliation. [Answer] I'm reminded of Mary Shelley's Frankenstein, wherein the Monster learned english from eavesdropping on another person learning English. That seems to be the most likely way for an animal to pick up on the language. From there I would think it would be mostly body language and pantomime. Much like an infant communicates at their stage of development when they can understand speech but not speak properly. There would be noises to draw attention, and then pointing/circling/touching that would indicate the rest. --- However, I think there are real questions as to whether the animals would want to communicate with civilization at all. Accepting the premise that the animals are friendly and working together, they would likely be able to sustain and support themselves as their own society. They already understand each other, and you've said they are drawn together from their strange circumstances. To that end, the first interaction from humans would likely be by people accidentally discovering them in large unsettled woods or other areas. Noticing a tight circle of animal dens, or observing a group of different species working together in a river to catch fish. The sentient animals would likely play dumb when possible to avoid the attention of the humans. ]
[Question] [ In this fantasy world there is no day/night but a constant mild light. There are also no seasons and the mild light is akin to the light at dawn or dusk. The sun doesn't really exist. How would the plants and animals differ? I assume sleep would look pretty different as well as photosynthesis. [Answer] Since in your world, there are no natural time cycles, life will not have an external synchronization. Therefore the main changes in your world will be to changing weather (unless your world doesn't have that either). Instead of day-active and night-active animals, you might have dry-active and rain-active animals. Some processes will still be cyclical because the cycles are not imposed but inherent in the process. For example, the predator-prey relation [can lead to periodic cycles.](https://en.wikipedia.org/wiki/Lotka%E2%80%93Volterra_equation) Also biological processes often come in cycles not synchronized to external triggers (the most obvious one being menstruation). However, the complexity of ecosystems and biological systems probably means that the whole timing relations would be more chaotic, with several different cycles overlaying with more complex time behaviour. I could imagine that animals would not have fixed, synchronized sleep cycles. While the brain needs sleep, some animals like dolphins can [put parts of their brain to sleep.](https://en.wikipedia.org/wiki/Dolphin#Sleeping) I imagine in a constant light world, such mechanisms would be more common also to land animals. In herd animals, it might also be that different animals sleep at different times, so that at any time some animals are awake and can react if predators arrive (which also can happen at any time). To minimize the risk that all members of the herd sleep at the same time, those animals would likely have *different* sleep cycles, so that a synchronization is excluded. If the average light intensity is the same as in our world (just without the variations), photosynthesis would not be much affected; the plants would simply do it all the time, instead of only half of the time. However, neither plants nor animals would need to protect against intense sunlight. [Answer] There is such an environment on Earth, called the Twilight Zone or more formally the [Mesopelagic Zone](https://www.wikipedia.org/wiki/Mesopelagic_zone). Notably, it is insufficient for photosynthesis. But how dim do you intend? Earth is rather dim according the the residents of [Bellerophon](https://www.wikipedia.org/wiki/51_Pegasi_b#Name) or [OGLE-TR-56b](https://www.wikipedia.org/wiki/OGLE-TR-56b). Hal Clement was prescient with [Iceworld](https://www.wikipedia.org/wiki/Iceworld) in 1951. An environment is ruled by available energy. Having far less energy on an absolute scale could be abundant if the chemistry is designed to work at that energy level. Such molecules are fragile by our standards, and the lower temperature is required so as not to smash them apart with random motion and nearby molecules rocketing through it. Just as the natives of Sarr, breathing sulfer and drinking copper chloride, consider Earth to be impossibly cold and too dim to see well, [Nadreck’s kind](https://rads.stackoverflow.com/amzn/click/0974889571) finds Earth to be inhospitable with blood-boiling temperatures, vast oceans of solvent and highly corrosive atmosphere. If there are a suitable suite of reactions at the proper energy scale for life to exist using them, then that scale will be normal and comfortable. If not, then it will be too energy-poor for life to take hold. Where low light is an extreme environment that can be explored by life that finds something else more optimal, *then* it is seen to be impoverished and harsh for that life. In your case, the whole world is like that, so, it won’t be colonized by a biosphere that is comfortable somewhere else. It will be comfortable *there*, if it exists at all. To get the kind of situation you want, perhaps life evolved and thrived under different conditions; then the conditions changed globally, leaving non-optimal biochemistry to cling to existence. ]
[Question] [ One possible approach how to estimate extend of space colonization is to define costs of it and then estimate the investments the governments and organizations would be willing to pay. In an [excellent analysis](http://www.rocketpunk-manifesto.com/2009/09/price-of-spaceship.html) of starship costs on the Rocketpunk Manifesto blog, the author shows that currently, the cost of building the International Space Station is \$170 millions per metric ton, and if we are very, very optimistic, the building price of space ships could be comparable to building price of a modern airplane, approximately \$1.2 millions per metric ton. My question is: What is a reasonable estimate of building price and annual maintenance cost of a long-term working colony on a planet without breathable atmosphere, like Moon or Mars, *per metric ton of the colony mass*? What is a reasonably optimistic estimate how low could these prices fall once the technology is established? Do not include the transport costs, only the costs of building the colony itself. [Answer] You would want to include transport costs, as those would be by far the largest component, at least to begin with. It would be unfeasible to send the entire weight of the colony from Earth anyway. Nonetheless, you would probably want to send at least initial ample supplies of food, water, oxygen and some very dense power source (nuclear reactors are the best available, at the moment) simply to get the colonists started. There are several sources of costs that you must incur just to get and survive on your way there: 1. Cost of producing the components used or consumed as part of the core mission (trained crew, food, air, water and shelter for humans, energy for all the machines to be operated, various probes, robots and tools). 2. Cost of manufacturing the non-fuel parts of the means of transport to get you there. 3. Cost of fuel required to leave the Earth's massive, crushing gravity well. Since each bit of (on-board) fuel needs to lift itself in addition to the payload, this escalates super-linearly with payload. 4. Cost of fuel required to break and achieve a controlled descent through the destination's gravity well at the end of the mission (can sometimes be partially alleviated by aerobreaking -- using the atmosphere if it exists as a breaking mechanism, but this would not work on the moon) Now your establishment and maintenance costs will be very hard to calculate, since you didn't specify any of the assumptions you wish to work under? Would it be a single person, a few dozen, or thousands? Should we assume current technology? I'm not sure we even can establish permanent bases at all with current technology. Even the international space station, for instance, leaks a huge amount of gas into space, and new cylinders have to be brought in to compensate for the loss. The cost of shipping food from Earth for a permanent colony on the Moon or Mars would be prohibitive, given that a human eats between [400 kg](http://recipes.howstuffworks.com/question720.htm) and a metric ton of food per year, so depending on your planned population it would be a constant stream of expensive rockets. Now, add a few tech ingredients to the mix, and the potential costs fall. The lowest hanging fruit is advanced 3D printing: it can make a lot of tools on demand (so you don't need many redundant replacement copies), and make them sturdier than normally constructed ones while also using less mass (so you don't have to push as much stuff up our gravity well). Next, if you give your colonists the ability to use local resources to produce air, water, food and fuel, the stream of costly resupply decreases dramatically. But to do that, you need advanced nuclear power reactors, hydroponics, industrial extraction equipment, smelters, an entire industrial edifice that must be sent there. We don't know how to make most of this stuff work reliably outside our atmosphere. Now you can go further into future tech and cut down the costs further, such as fusion reactors (ample fuel on the Moon), space elevators (launch costs fall 10-100 fold), or go all out and assume self-replicating nanotech assembly which is a bit like a magic wand. In summary it's not a question that can be answered without specifying a full set of assumptions you are prepared to make, and requirements on the size of the colony, the permissible fatality rate, allowed radiation dosages, whether the colonists are there permanently or hope to return, etc. ]
[Question] [ In a Tolkein-like world, I want to devise a rehab program for Dwarves to course-correct if/when they succumb to treasure-induced [auromania](https://www.macmillandictionary.com/amp/dictionary/british/auromania). Symptoms include: * Paranoia - mistakenly belief that others took your gold * Developing a Pavlovian response to metallic "kling-klang" sounds * Burrowing long tunnels in a mountain without uttering a word in weeks * Hallucinations of glimmering, golden objects I want to approach the task from a mental health / social science angle. Namely, I want to apply some form of [cognitive behavioral therapy](https://en.wikipedia.org/wiki/Cognitive_behavioral_therapy) such as stress inoculation. However, I have very limited knowledge of the field and I think it would be time/effort prohibitive for me to aspire to be an "expert." ## Question If we accept the disposition to auromania as hereditary (part of Drawven DNA), how would modern mental health therapy, such as cognitive behavioral therapy, approach the condition? **Further clarifications:** * Case by case solutions are acceptable, macro policies can work too * Assuming Dwarven minds are comparable to humans (not species-specific) * Solution should be entirely psychological, self-driven (most external factors are immutable, ex: wealth of gold in the mountain - can't throw the gold away) * As pointed out in the comments, the origin of the condition may be relevant. Let's assume Dwarves have a genetic disposition to developing auromania * The condition doesn't have to be cured outright, but should at least be meaningfully mitigated > > My name's Durin, and I'm an auromaniac. > > > [Answer] Considering that dwarves are genetically predisposed to develop auromania, the scope of the problem is too big for individual interventions only. It is also not clear from your question how big the problem is and how destructive it to society. I am going to assume that auromania is seen as a pathology and is undesirable in this particular society. I think that dwarves in charge have to take a multi-prong approach: * cultural and social norms and values; * healthcare system; * individual therapy. **1. Discouraging gold-digging and hoarding** The dwarf government can use propaganda and various laws to achieve this. For example, private property can be abolished and locks are forbidden. There can be horror stories about gold diggers who snatch children or follow their hallucinations to their death. The country can have festivals that encourage simple lifestyles, cooperation, sharing, and so on. The culture would, probably, encourage highly structured activities, mostly in groups, where dwarves can support each other and take notice of any early symptoms of the disease. Rituals and routines are very helpful when dealing with mental issues. If the problem is extreme and the society fails to deal with it, mass exodus and relocation to the grasslands/plains/forests can be considered. As with any addiction, no exposure to a thing that causes addiction helps to minimise the cravings. **2. Healthcare system** Since dwarves are genetically predisposed, it stands to reason to assume that auromania is not rare. The dwarf government can establish research facilities, universities, hospitals, rehabilitation centres, support groups, and a network of social workers to deal with the condition. This infrastructure does not have to be high-tech. It can be envisioned in medieval terms. However, it should be centralised, well-funded, and based on science (whatever this science is in your world), not on superstition. The condition should be well-documented and remedies should be known, even if your society has not reached the level of genetics. In a high fantasy setting, you can probably use monasteries as the foundation of this healthcare system. Professional associations (guilds, military orders, etc.) can also play a significant role. They would also provide structure to lives of recovering dwarves and psychological support. **3. Individual therapy** I am not expert on CBT, but I do not believe that it is universally helpful. When it comes to mental disorders there is no 'one-size-fits-all' approach. Depending on the stage, the severity of the symptoms, and personality, different approaches should be used. With this said, you still can focus on CBT in your work because it works for that specific dwarf. I think that you should consider using CBT as a preventative measure (your teachers and priests can be trained in it) or for patients that exhibit only minor symptoms and are on early stages of auromania. If a dwarf completely lost touch with reality CBT alone can be ineffective and should be supplemented with medications and/or institutionalisation. As for specific techniques, I would look into [substance use disorders therapy](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2897895/) and [CBT for psychosis](https://www.psychiatrictimes.com/view/cognitive-behavioral-therapy-psychotic-disorders) (these links are just examples of information that would be useful). Most of the techniques would focus on: * establishing a connection with a patient (delusional patients are usually reluctant to cooperate and can be mistrustful); * working on motivations (mixed success in this area); * developing coping mechanisms that help to filter out hallucinations and reduce their number; * increasing self-esteem; * managing cravings; * learning behavioural patterns and skills for better social adjustment; * preventing relapses. All of this will be applied on a case-by-case basis depending on the severity of symptoms, patients response, therapists training, and so on. For psychotic cases, psychological therapies are tailored to individuals. [Answer] As far as the hyperfocus symptom akin to ADHD, here’s a good article to read. <https://www.google.com/amp/s/www.additudemag.com/understanding-adhd-hyperfocus/amp/> My favorite section: “time limit and expect her to stop. “I tell parents they’ll need to do something to break the ‘trance’ their child is in,” says Silver, “such as tapping him on the shoulder, waving a hand in front of his face, or standing between him and the television or computer screen.” Unless you do, he says, the child may not even realize that you are trying to get his attention. “These children aren’t being disobedient,” says Nadeau. “Their brains just aren’t registering what you’re saying. That’s why the interruption should never be done angrily, and why you should allow a few minutes for the shift in attention to occur. It’s almost like pulling someone out of a dream.” ]
[Question] [ ***Short version:*** Just as the title says, I'm looking for a quick-and-simple point-and-click cartographic software to easily make a basic map. ===== ***Long version:*** This might be asking too much for too little, but I wish to make a simple map. It needn't be beautiful, or highly detailed (these would be nice, but are hardly necessary). I need only the level of sophistication that one might attain with five or ten minutes of pen and paper sketching (I would go this route, but don't have a scanner) – though better than a very simple hack job in MS Paint. I have the map in my mind, but would be willing to work with randomly generated stuff if I could add/subtract/edit the result. It's several continents wide, with some mountain ranges, badlands, city markers, etc.. Its purpose is merely readers' reference in a book (e.g.: **[Narnia](http://d3n8z25y871gwm.cloudfront.net/wp-content/uploads/2016/10/07195804/naridia_archenland.jpg)** or **[Middle Earth](https://d1x7wtd7o9kqaz.cloudfront.net/app/uploads/2013/03/Middle-earth.jpg)**). It could be something as simple-looking as (or even more so than) **[this map](https://opengameart.org/sites/default/files/FantasyWorldMap_2.png)**, **[or this one](https://i.stack.imgur.com/4GTaD.jpg)**, **[or even this one](https://pre00.deviantart.net/24c8/th/pre/i/2015/355/f/0/generic_blank_fantasy_map_by_curtisw800i-d9kwm5l.png)** – though preferably more aesthetically pleasing than *[this example](https://cdna.artstation.com/p/assets/images/images/003/893/558/large/michael-moylen-map-outline-and-boarders-recovered-just-in-case.jpg?1478288571)* or *[this other one](http://www.bigskywords.com/uploads/1/2/8/0/12804055/1465457_orig.png)*. I have pored over several lists of really excellent of cartographic software. • <http://www.rptools.net/> • <https://www.cartographersguild.com/showthread.php?t=1407> • <https://shaudawn.deviantart.com/art/Free-World-Building-Software-176711930> • <https://medium.com/universe-factory/mapmaking-software-65c0318fd3a6> • <https://alternativeto.net/software/campaign-cartographer/> • *and more that can be found here on StackExchange* As a result, I've installed GIMP and AutoREALM, but while each has some wonderful bells and whistles, both are more labor intensive than this need be. ===== ***Summary:*** Where might I find map-making freeware designed for the use of a lazy idiot? It's embarrassing to say this, but I'm just looking for ease of use, not something with awesome features. [Answer] For my money you can't beat hand drawn maps, ever, but you've indicated that you're too lazy for that *so*; [AutoREALM](https://sourceforge.net/projects/autorealm/), AutoREALM and AutoREALM are the best options you have for world or country scale maps. Sorry probably you don't want to hear it but AutoREALM is literally the only decent software I've ever found that doesn't require effectively pixel scale manipulation to get a really decent result. There is also [Campaign Cartographer](https://www.profantasy.com/products/cc3.asp) but I understand it's quite expensive and even more complex and less user friendly than AutoREALM, and there is [Inkarnate](https://inkarnate.com/) which is web-based, not downloadable (though the created maps are), also not free for the full version, the Beta version is still free at this stage; the maps are gorgeous and the interface is reasonably nice in my experience but is still fiddly. [Cityographer](http://cityographer.com/) is good for automatic generation of urban environments, I have either that or something very similar but I can't find it right now. [Dave's Mapper](https://davesmapper.com/) is an online tool that uses pre-existing tilesets to build dungeon (in the DnD sense of the word) scale maps, you do have to be picky about the tiles you use to get good results but they are there. [Answer] I've an alternate idea for you: Unity (game engine) free, and the amazing worldbuilding plugin called Gaia... I use it for, well, Unity worldbuilding... and it's pretty darn amazing. ]
[Question] [ **EDIT:** (Important) M. A. Golding commented that the regalecid method of locomotion would be unfit for a constricting predator, so I have **completely redone the taxonomy of the sea serpent**. They are now eels, closely related to moray eels. The sea serpent taxon has been upgraded to family Serpentimaridae, as opposed to the old subfamily Serpentimaria. I don't have time to draw up a dendogram right now, but they're in the suborder Muraenoidei, in a clade with moray eels. I think that the current lack of answers is because I have not alluded much information as to the physiology of these animals. Here is a rough sketch I made in Paint (Originally a preparatory draft for a real illustration of sea serpent anatomy): [![enter image description here](https://i.stack.imgur.com/SoB6k.png)](https://i.stack.imgur.com/SoB6k.png) Note: the reproductive and excretory systems are not shown here, but do not affect their potential size anyway so it shouldn't matter. So, if the heart needs enlarging, or I should have a bundle of ganglia towards the back as an extension of the CNS, or any other amendment, please let me know. *Hopefully*, I'll get some answers now that I have clarified a bit more. --- This is currently the sixth question about my ongoing worldbuilding project on viable fantasy creatures. I'm too lazy to link all of them here, but the last two were: [What kind of animals are my trolls?](https://worldbuilding.stackexchange.com/questions/114418/what-kind-of-animals-are-my-trolls) and [How can I explain the evolution of my giants?](https://worldbuilding.stackexchange.com/questions/114289/how-can-i-explain-the-evolution-of-my-giants?noredirect=1&lq=1). You can find links for the rest at the latter. Now, from giants and trolls we progress to the largest creature in my project, the **sea serpent** (Subfamily Serpentimaridae). These beasts are not serpents but fish, in the suborder Muraenoidei. I want these serpents to be massive, at least the length of a blue whale - and upwards from there. Seriously, if the answer is "600 metres", then I'll take that. But, I rather doubt that a fish could grow to a length of 600 metres (Feel free to prove me wrong), so I'll have to find out what's rational and what's not. Sea serpents are constricting predators, like boas, and use their musculature to crush whales - and, on occasion - ships. They also have pharyngeal jaws, like their close relatives the muraenids, which allow them to swallow a rowboat whole. I haven't figured out what oceanic zone they'll inhabit, but any is fine for me really. Deeper zones would be convenient as an explanation for why they've remained undiscovered, except for reports by sailors throughout history. They need to be large enough to be able to create waves with lashes of their tail, as well. To summarise: **How big could Muraenoideian sea serpents be?** [Answer] To answer your question, consider how thick would be the body of the largest animal you intend your sea serpent to prey on by constriction. If, for example, the prey has a thickness of 1 foot and is perfectly cylindrical, it will have a circumference of 3.14 feet. If the sea serpent wraps around the victim three times and has length left over, it must more than 9.4 feet long. And the giant snakes known to science would usually be 10 to 20 feet long if they attacked prey a foot thick. If, for example, the prey has a thickness of 10 feet and is perfectly cylindrical, it will have a circumference of 31.4 feet. If the sea serpent wraps around the victim three times and has length left over, it must more than 94 feet long. It could easily be 150 to 200 feet long accounting for the extra neck and tail lengths. I point out that the longest prehistoric or contemporary animals known to science had or have lengths in the region of 100 to 200 feet. And some scientists find such lengths amazing because of various factors including the time it takes for signals to travel the length of the body along nerves which sometimes are single immensely long cells. Some scientists would claim the longest animal proven to have existed must have been the longest animal possible, while others would say that longer animals might be possible. <https://biology.stackexchange.com/questions/44788/has-the-human-body-the-greatest-total-length-of-nerves-of-all-animals>[1](https://biology.stackexchange.com/questions/44788/has-the-human-body-the-greatest-total-length-of-nerves-of-all-animals) How thick can the body of the constrictor be if it is capable of bending enough to constrict around the body of the prey? Depending on the flexibility of the constrictor, what is the maximum possible relative thickness of the constrictor's body compared to the prey's body? If a sea serpent is flexible enough to constrict a victim with a diameter of 10 feet, will the sea serpent be flexible enough to constrict prey with diameters of 5 feet or 1 foot, or will those smaller animals simply escape out of the oversized loops of the constrictor because it can't constrict tightly enough? It seems to me that a growing sea constrictor will only be able to constrict animals within a certain range of body thicknesses. It will be unable to constrict thinner or thicker animals. Once you have decided upon the body thickness necessary for your constrictor to constrict prey within the desired thickness range, you must then decide how your constrictor is proportioned. The length of your constrictor would range from X times its thickness to X plus Y times its thickness. And what would be plausible relative proportions for your sea constrictor? You can study the proportions of various snakes that constrict. You could make your sea constrictor proportioned between the stubbiest snake that constricts and the most elongated snake that constricts. Or you can make a more generalized study of the relative proportions of all the long, narrow creatures in the world. Or, if you decide that your sea constrictor should have a certain width, you can calculate what its body mass would be at various lengths. If it is carnivorous it shouldn't be much more massive than the largest known present day or prehistoric sea carnivores or it probably won't be able to feed itself. Or, you can decide what is the largest mass sea creature it can swallow whole. Since it will probably usually eat several smaller sea creatures for a meal instead of only one of the largest it can eat, you might decide that the largest creature it can swallow whole is as large as the largest meal it needs, and then decide what body mass a creature would need for that amount of flesh to make a meal. I think that a combination of those methods should enable you to decide what size your sea constrictors usually are, though of course there could be freak exceptionally small (boring) or large (terrifying) specimens. I can't help thinking that even the smallest monster you might decide upon would be horrifyingly large. ]
[Question] [ Having recently been to [Mammoth Cave National Park](https://en.wikipedia.org/wiki/Mammoth_Cave_National_Park), I've been considering the caves of my own worlds, and more specifically their formation. Now while not all caves are formed from limestone, it is the most common cave material, given that water seems to so readily dissolve it. The groundwater drills into the limestone--or other stone depending on the cave system--going where water does by taking the path of least resistance, or in other words, dissolving the less dense stone first, eventually forming what we recognize as caves after the water table recedes enough for the cave network to become more readily accessible. For a more visual representation, see [this short, interactive simulation](http://www.classzone.com/books/earth_science/terc/content/visualizations/es1405/es1405page01.cfm). With that in mind, I would like to be able to simulate the formation of the cave networks in my own worlds, but I don't have massive slabs of limestone on hand nor the time it takes to see how water will form caves within them, which is why I'm looking for a small-scale solution preferably meeting the following requirements: * Either digital or physical is fine, but physical simulations should have components that are easy enough to obtain * Simulation should produce three-dimensional results or a representation of three-dimensional space * The resulting model should be something one could easily split apart without disrupting the final results to look inside and see the final formations * Simulation should have some way to allow for the density of the simulated limestone to be controlled to allow for more variety in cave formations * The volume of the model should be able to be changed to allow for a wider area of effect on both the depth of the system and length of the tunnels overall * Whether models represent stalactite/stalagmite formations is not real important overall, but models that do provide that type of insight are obviously appreciated. [Answer] I am unable to find software that can do what you're asking. Which isn't surprising. * The modeling process is [quite complex.](https://www.uow.edu.au/~minjie/pub-ps.dir/IJCSNS-2.pdf) * Caves, themselves, are [quite complex.](http://www.goodearthgraphics.com/virtcave/virtmap.html) For example, [this article analyzing cave formation on Mars.](https://pdfs.semanticscholar.org/b1bc/69295b4d2c8aebba7015e9c49226044434c4.pdf) Your biggest problem is that geological composition has a lot of seemingly random conditions.1 Geological density, stratification, and distribution. Chemical composition (probably down to the the square-foot level). Hydration and hydraulic effects. Heat distribution and the effects of atmospheric contamination. And that's ignoring whether or not the cave formed from sublimation, water evacuation, or lava. And that's just what I can think of off the top of my head. And given my experience with computer modeling in the past, the software requirements you've listed are easily 75-150 million dollars worth of development depending on the input of dozens of PhDs, spectactularly trained computer engineers (many from the video game industry), and 6-10 years of development time. I wouldn't expect it to be freeware or shareware. --- 1 *They're seemingly random because it's incredibly difficult to see the "big picture" in something so complex as planetary formation and evolution.* ]
[Question] [ So to start, let's assume that this hypothetical life form relied on something similar to LNG (liquefied natural gas) - mainly relying on ethane - as a solvent in the same way humans rely on water. Let's also assume that they breathe hydrogen, use acetylene as glucose, expel methane, and that they are carbon based like us. Knowing that they do not use oxygen, what element makes for the optimal choice in acting as a hydrogen carrier at cryogenic temperatures, in the same way hemoglobin uses iron to act as an oxygen carrier? [Answer] I like the premise! Your critters could use a metal hydride. <https://en.wikipedia.org/wiki/Transition_metal_hydride> You would need to bake up some heme ring equivalent to carry the hydride metal and control its uptake / release of hydrogen. Or how about oxygen! You could have a large ether in which the oxygen reversibly forms an alcohol, accepting and donating the hydrogen. ]
[Question] [ ## The Basics There is **no FTL**. Most spacecraft use He3-De fusion Torchdrives, capable of **performing sustained multi-gee burns**. Most torchdrives can also use fuel that is delivered by accelerators elsewhere in the system, so fuel doesn't have to be used until the actual battle begins. **Stealth exists** in the setting, but it is very limiting and requires specialised rockets. It relies on cooling, anti-radar coating, meta-materials and on specialised rocket designs. Stealth vessels are generally limited to Hohmann-Transfer orbits and their effectiveness depends on the state of the sensor networks. (Interplanetary space is usually save, but going inside a well settled planets orbit is very risky.) **Automation is high** and if there is a crew of biological humans present, they are genetically and biologically enhanced. Pure AI, robots or uploaded minds are more common alternatives. While **defence has beaten offence in the realm of cyber-security**, breaking into the systems on a hardware level is usually possible and most factions have a numberof backdoor into each others systems. Ultimately, cybersystems have taken on a rather biological structure, with defence systems acting much like our immune systems. Data is often filled with misinformation, propaganda, computer and memetic viruses and other nasty stuff. So everything must be done with caution. ## Weapons **Missiles are used over long ranges** (most commonly a lightminutes to a few lightseconds, though their range isn't actually limited, as they can just enter a cruise mode). Usually missiles have an acceleration stage (metallic hydrogen, fusion or antimatter rocket or a beamed energy based propulsion system). This acceleration (hot) stage is then scuttled and a stealth (cold) stage is employed alongside a cold gas thruster, which operates on evaporating liquid helium. Additionally, cooled balloons are deployed as decoys, if the missile believes, that it has been discovered. This stage is only used to avoid the attention of long range energy weapons, which could otherwise begin decemating the missile swarm from a few lightseconds away. As soon as the missiles have been discovered (either the enemy missile wave has closed in or they start taking effective energy weapon fire), they scatter their submunitions. The submunitions have been brought up to speed during the acceleration stage and focus on manovering. They fight enemy missiles and attempt to get a killing shot on the enemy vessel. Common **submunitions** are kinetic impactor (crude diamond blocks, but their impact energy creates a shock wave that can disable an entire spacecraft), shaped nuclear lances (small angles with huge ranges, wide ones against submunitions, additionally they work well against sensors), lasers (chemical or nuclear powered, short lived and more interesting for electronic warfare than actual damage), radio jammers, thermal particles, radio shaff and sometimes nukes for planetary bombardment. **Energy weapons** fall into several categories and work best as soon as targets are about a lightsecond away. Inefficient Gamma and X-ray lasers, UV-Lasers (most commonly used and often capable of operating in the visible part of the spectrum as well, if more efficiency is required), ultra long range (several AU) laser guided particle beams and macron cannons, which fire nano-particles filled with fusion fuel at a few percent of light. **Point defense** is done by batteries of masers and infrared lasers, kinetic or macron cannons are sometimes used to provide a final shield against incoming submunitions. Some navies use nuclear bombs instead. While those do indeed clear away incoming submunitions, they cause damage to the spacecraft as well. **Armor** is made from carbon super materials, which are further strengthened via electromagnetic effects. Most sections of armor rotate rapidly to offer the largest possible depth against energy weapon fire. Many levels of redundant point defense and sensor systems are buried inside. Armor is usually several meters thick. Non-rotating sections are even more massive. Strong magnetic fields are often used to further reduce the effects of plasma weapons. **Radiators** never truely converged on one design, however all designs today pay the energy tax of using heat pumps to achieve as high a temperature as possible to reduce surface area Either short, solid radiators are used all over the hull, operating at a few thousand kelvin and ready to be replaced several times over or particles and droplets are ejected and brought back in by powerful magnetic fields as soon as they've cooled down again. Additionally large, dumpable heatsinks are used to allow the vessels to operate even when their standard heat budget has been exceeded. **Drones are commonplace**. The most common drone is arguably the missile. However, most other drones operate closer to the spacecraft itself and offer high acceleration with very limited abilities. Scouts are sent ahead and very versatile, telescopes deploy behind the battle and try to spot cold missiles (there is a trade of between keeping their spin-stabelised multikilometer mirrors save and keeping them close enough to deliver information in time.), deflectors have strong mantetic fields and try to deflect particle beams by a few parts of a degree, so it misses big static targets (they are commonly used by stations) and mirrors allow the vessel to fire its laser at the enemy from a better angle. Other designs like breaching pods exist, but they are niche systems. ## Combat Generally combat **begins at about a light minute** out. Missiles are fired. Pincering the enemy with missiles can be very effective. This is why a single stealth vessel can devestate a constallation of spacecraft if it can launch it missiles via gauss gun from an unexpected angle. The number of attack vectors, density of the swarms and number of waves depends on the situation. Additionally the missiles are highly modular and programmable, so their setup, complement of submunition warheads and behavior can be determined as the commander sees fit. Usually there is a lot of **missile on missile combat**. Either the passing swarms fight each other or an attacking swarm fights an defensive swarm. **Point defense is good, but far from perfect**. Once the submunitions have closed in to a distance of a few thousand kilometers, they can use particle lances and lasers to surpress sensors. Defensive nukes make trying to overwhelm the point defense ineffective, so the attacker tries to avoid offering on good target for such a sweeping defensive strike. Instead they try to grind down the defensive with an optimal number of submunitions to get at least one fatal hit (either a kinetic impactor or particle lance that will penetrate the armor). The chances of annihilation, critical damage, noncritacal damage and a perfect defence are roughly equal over all battles. **Energy weapon combat begins around one lightsecond.** It is rare, as it can only happen if one combatent was ambushed or both want to engage. Normally one side retreats or surrenders after the missile phase is over. If the enemy isn't a combat craft, it will be annihilated in seconds. If both are combat craft and in a roughly equal state, the looser will take almost as much damage as the winner. ## Shiptypes **Scout drones** are usually employed as gunboats. **Stealth craft** either operate as spies, missile carriers (using a gauss gun to lauch cold missiles before sneaking away), strikers (which dump their stealth superstructure and trun into regular torch craft in a fight) or carries for torch craft. Stealth crafts are usually much bigger that combat craft, as they need huge amounts of coolant to operate. Torchdrive vessels all tend to fall into six groups. **Destroyers, Armored Crusiers and Battleships**, which are optimised for the **combat constallation**. In practice most navies use just two or even one type in the battle constellation. Size doesn't translate into endurence or performance. Nukes and kinetic impactors destroy a 100m vessel as throughly as a 1000m one. Performance depends on the thrust to weight ratio. **Frigates, Cruisers and Battlecruisers** tend to be more diverse and trade versatility for combat performance. They can operate **independently**, sometimes for years. ## Size and Design Stealth craft tend to be tapering tubes about a kilometer long, as this allows them to carry enough coolant without occluding too many stars, even while using light bending meta-materials. They always try to keep their front towards the sun. Combat craft tend to be between 50m and 150m. This usually allows them to preamptively dodge energy weapons with their heigh acceleration. Independent craft are generally bigger and tend to have centrifuges and auxiliary craft as well as slots for mission specific modules. Depending on the type they are between 75m and 500m. Their form is optimised for the use of rotating armor, so long, outwards curved cones are the norm. The main energy weapon tends to sit in a transperent frontal cone, that is optimised to let the weapons wavelengths through. Particle beams and macron cannons use shutters. **Is this system of space combat plausible? Did I miss anything obvious?** Thanks for reading this rather long question, I build this system over a long time and am interested if it holds up as a whole. [Answer] **Fortifications.** 1. The action is 99% concentrated in solar systems. Interstellar space is empty. 2. Action will be concentrated around some planets. The area is physically large but practically small because there is nothing else there. 3. It is hard to hide in space. There is no topography. There is little to hide behind. For an area of interest around a planet, multiple fixed sensors will be present. Spacecraft in the areas of interest will be known. 4. It is nice to not have to worry so much about defense. Fortified moons and asteroids in orbit around planets of interest do not have to worry as much about defense. These fortifications armed with the weapons you describe with multiple distributed eyes over the system will control 99% of spaces of interest. Heavily armed fortifications will quickly obliterate unwanted ships entering the area and closely monitor the rest. Fighting will be rare. [Answer] I think this is well thought out, however I didn't do the math on *anything* and maybe you overestimate the capabilities of some of your systems. A lot will depend on the relative capabilities of your various systems, the basic logic appears sound. I doubted anything can hit a target at 1 lightsecond distance, when said target can sustain several g acceleration - however: To get from zero speed to 200m distance (one ship's length + safety factor) in one second ("flight time" of the laser) needs 400g, which is way beyond what your torch drives can do. So hitting a target at these distances is certainly possible. If we assume 1.1 s for target aquisition (0.1 s for calculation and lining up the shot), we are still at ~90g. So we can assume that lasers could hit within m or tens of meters where tah shot was aimed, even if the target random walks at high accleration as long the accleration is not ludicrous. What struck me when reading your description is two questions: * who's gonna pay for all that highly advanced and energy-hungry stuff? * what are they actually fighting about? To answer my second question, one goal military / political goal that can be achieved with the fleets you describe is total control of space around a planet. What is less clear to me if a planet or planetoid sized target can be *protected* within your universe - but I would assume that many planetary defences couldbe overwhelmed with lots of rocks or something. So a large fleet can domiate space around a planet, it can't protect said planet from attacks and no space dominance can guarantee the the population on this planet will be obedient and productive. From my first question, I think it follows that all sides in a conflict will look for high effect, low cost weapons and tactics - the idea from Kim STanley Robinsons 2312 comes to mind, acclerating or nudging microasteroids from many different places so that they converge at one point. Possibly supercooling them to 4K first to make detection harder. This also means that evera space combat asset has to be a ship, must be able to evade low tech weapons at short notice. The battle fleets need missile supplies, He3 supplies, energy supply from microwave stations or so, the telth ships need coolant tenders ... in the end, the fighting craft are not so much the tip of the spear as the end of a very long and complicated supply chain. Which could be disrupted by any of the weapons or tactics we discussed so far. **To sum up my ruminations:** * I don't think stationary defenses in space make much sense in your system * you should look for more low cost, nuisance attack options, though I'm not sure there is much beyond small and large rocks ]
[Question] [ So, I had this idea about a sapient alien specie paritally based on the reproduction of the schistosoma [![](https://i.stack.imgur.com/AiIWP.png)](https://i.stack.imgur.com/AiIWP.png) A flat worm specie in which the male is notorious bigger than the female, and this have a curvated chanel in which takes the female for give her protection, this causes a constant copulation while are together, they bond themselves by the presence of a suction cup. Females can go out from this chanel and find other males, but the males compete for evite this. Then I had the idea of an alien specie in which the female have a little size with a notorious inteligence, maybe sapient, compared with the male which would be some times bigger than the female and with less intelligence. The reproduction of this specie consist in the selection of a male by the female, the most capable and useful for her life plan The males for some time live separately from the females but when they reach sexual maturity they look for them and congregate in groups where they exhibit their abilities and the females choose them to later bond them together (In this part it will not be decided if it is a perpetual union such as monkfish or a temporary union from which the female can detach herself and look for another male, but this will depend on the following questions). With that union the females have practically acquired a tank or living "mecha" that they control with their own mind obviously with separate functions to the mind of the male so as not to complicate things. This would give a much more capable union for both female and male who benefit from having great strength and intelligence which otherwise they would not have because during their development they could only invest energetically in one or the other. Probably this evolved because males were aggresive since their birth and they were losing that aggressiveness as they created and despite how hostile it seemed, only other young but somewhat older males would be responsible for coupling them in their herd or perhaps the same females would ensure that they did not starve by restricting them like an animal wild; The point is that they would miss out on the intensive care that females would receive with what they would acquire the necessary knowledge to live in society. The characteristic of growing to giants and bonding the females, it could evolve from an extreme need for protection against predators, especially against the offspring and the females themselves, the same reason why male offspring are also so aggressive, to protect themselves from driving away predators by protecting their own litter this made the males invest all their resources in strength, size and perhaps other defenses (horns, armor, fangs), further enhanced by sexual selection on the part of the females, meanwhile the females had to keep caring for the others therefore they learned to make tools over time and no longer depended so much on males, but still it was a great use to stay attached to a male who could give more use to certain tools. I have thought about shapes, anatomies and body format for make it viable but but I'm still indecisive about certain things that I don't know how they will work, based on different earth animals, gorillas, elephants, humanoids, crabs, beetles but I could not decide. So, my principal problems are the next (but if you see other at myinitial idea do not hesitate to let me know and make your own proposal): * **Are there other ways to do the gamete exchange without the copulation? or alternative, does a constant copulation would permit the birth?**, if there are bounded together for mating, the initial thought is that they genitals are the part which start the bonding, but if are permanent blocked, It will not be possible to give birth, so until now options that I have considered is that the sperm travels through a different conduit, perhaps through a bloodstream (which I do not know if it is possible) or that the female has three different cavities, for the copulation, defecation and childbirth functions, or that the male's "fertiliator" is very thin. * **Are there ways for two organisms to "fuse" them?**, I mean, enough fused for share their lymphatic and nervous system (to control the body of the other with chemical impulses), for example female monkfishes can control the sperma production of their parasite males, which bit the females for bound their body with the female, in this case the oposite. Also depending on the answer of this question, I will know if the two bodies are permanent bounded or if females cac free herself and find other male or if an only male could have more females. Aclarations * Their intelligence is not that far, females are at the human level, and males like a gorilla or even a primitve hominid, "brute" is just a simple way to call it. * Other of my inspirations is a simplified vision of the Platonic myth of the better half, that together they are stronger than separated by, each one has something to contribute to their relationship to make it mutually complementary. Finally, considering all, how is this possible? [Answer] ## Evolution It's common in animals use use the same opening for copulation and birth, but it's not necessary. The reasons it's common is because it's evolutionarily simpler to reuse an existing mechanism or body part than to create a new one from scratch, and because growing and maintaining more body parts requires more energy. This doesn't mean it's impossible to have separate openings for different functions, simply that it's less likely to happen without some evolutionary pressure. Anyway, I have some answers to you questions, inspired by the sexual behaviors two real-life animal: bedbugs and anglerfish. Beware of slightly gory details. ## Bedbugs and traumatic insemination This is a trait that actually evolved in a bunch of invertebrate species, but it's very prominent in bedbugs. The idea is, instead of taking the time to carefully line your genitals up with your mate you just evolve a spine at the tip of the penis and stab the female just about anywhere and insert your sperm. The sperm kind of float around until they find the ovaries and impregnate. There are several associated byproducts of this. One is that males often inseminate other males as well, hoping it will end up in the testicles where it will then be passed on to another female - so called "penis fencing". Another is that female bedbugs have evolved a special organ to reduce the effect of traumatic insemination. It's not clear exactly how it works, but current theory is that it helps reduce infection. ## Anglerfish and the fusing of bodies Anglerfish live deep in the ocean, and the population down there is really sparse which means an anglerfish might only encounter another of its species a few times in its life, and it's unlikely that this will match up with when they are ready to lay their eggs. Their strategy to deal with this is that the male is much smaller than the female, and looks quite different. When they encounter each other the male bites the female on her side, and them slowly he becomes a sperm-producing parasite. Through the bite location, their circulatory systems fuse and many of his organs dissolve. The rest of his existence is now centered on one thing: when the female is ready and releases her eggs, he sends out his sperm to fertilize them. That's it. ## Combined on a macro scale It's clearly possible to attach to another creature and join you circulatory systems together, and there is no reason the joining spot couldn't be centered on a penis stab instead of a bite. On a bigger and more complex animal you cant really count on sperm travelling trough the body to where it needs to go, so just make sure the penis stabs directly into the uterus. So timing of sperm insertion is up to the male. The female might release eggs regularly on on command, depending on who you want to be in control of reproduction. While joining onto a bloodstream is simple if you can overcome the immune response since it's modular, taking direct control of a nervous system is harder since it's all directly connected to a brain already. That said, you don't really need full control but just ways to send signals. This could be sounds or limbs tapping out commands, but cooler would be simple nerve connections the male can detect but which don't directly control movement. The female can send out general signals, such as "go there" or "fight him" or "give this child your food" very fast, and the male is trained to respond to these because the females intelligence gives better outcomes. Maybe more complex signals for precise tool manipulation are also possible, but take longer and so are hard to use in emergency situations. It would also be interesting in that the male are always actually in control of themselves and can ignore the female if they wish - they just don't usually. Great for dramatic storytelling: you could outmaneuver another pair by making the male overcome with some emotion so he stops listening to commands, and then he's simpler to trick than the female. ]
[Question] [ On the Atomic Rockets site, there is [a series of handy tables](http://www.projectrho.com/public_html/rocket/usefultables.php), the first of which is aptly named "The Boom Table", providing examples for a wide range of energy releases (in both Joules and TNT equivalent). 3.2×10^26 Joules, or 77 petatons of TNT, is listed as being sufficient to blow away Earth's atmosphere, and presumably cause catastrophic damage to the planet's surface. Assuming the math to determine that this release would be sufficient to nullify a world's atmosphere is accurate, **what planetary fortifications would be sufficient to withstand an indirect impact?** Ideally, the atmosphere within said fortifications would remain at survivable pressures. Ideas I've considered: 1. Terranean nuclear/WMD bunker. Designed to withstand extreme temperatures and pressures. Direct exposure to the blast wave of super-compressed atmosphere would be extremely risky, regardless of the materials used to construct it. 2. Subterranean nuclear/WMD shelter. Designed to withstand extreme temperatures and pressures. No direct contact with the blast would be made, but would nonetheless suffer from the considerable seismological events triggered by such a massive explosion. 3. Suboceanic facility. Seismological effects would still be considerable, but the catastrophic tidal effects would be a far more apparent. Of these three, the subterranean shelter seems most-feasible, but is not without its share of Achilles' heels. **Edit:** For clarification, a terrestrial solution would be preferable; simply avoiding the effects of the blast isn't quite the same as sufficiently withstanding it. **Edit 2:** By "indirect impact", I mean that the structure is not directly beneath/taking the full brunt of the explosion, but rather situated anywhere between ground zero's perimeter and the opposite side of the world. As for materials from which the shelter would constructed, a near-futuristic (~100 years into the future) technology level may be assumed, and all of the advances in metallurgy and materials sciences that accompany it. I am also not asking for a structure to be designed, the physics behinds its strength in accompaniment; merely a conceptual presentation as to what sort of structure would be able to withstand the blast wave, given appropriate geography. [Answer] # Subterranean, very deep, and multiple-shielded. You carve out a very large cavern under a mountain, and reinforce its walls with concrete. You now have a massive, hollow cube. Inside the cube, you build a smaller cube - perhaps three meters less on each side, the sides connected with springs and hydraulic active shock dampers. Sensors and laser meters maintain the proper distance between the walls, within the limits of tolerated acceleration. And inside *that* cube, a third cube, which is the real bunker. The space between the cubes is evacuated, and the shock dampers are autonomous and self-contained. Assuming that the impact is not enough to crack the mountain open (it might crack the outer casing, though), no mechanical shock could travel through the vacuum, and if properly managed, a 3 m end run is enough to counteract enormous shocks (and of course you can design a larger cavity if need be). The shock wave would travel through the mountain at about 3500 m/s; by building the bunker at a depth of about one kilometer, you get around one third of a second's worth of shock analysis for the dampers to optimally respond. This is how Cheyenne Mountain was initially armored against nuclear impacts and earthquakes, only written *much* larger (and using reactive technology instead of just passive springs). [![enter image description here](https://i.stack.imgur.com/VRwFK.jpg)](https://i.stack.imgur.com/VRwFK.jpg) [Answer] You’ve missed a potential siting: **Submarine, but free-floating** Well, sort of free-floating. If sited in suitably deep water but tethered to the ocean floor with multiple cables then a ‘floating’ fortress will be shielded from the energy above by the depth of the ocean and from the cataclysmic spasms of the earth below by the fact it’s not rigidly bolted to the floor. In deep water there’s no real tidal effects (or wave effects) to worry about (the water has so much space to flow around you that it can’t exert a whole lot of force), so as long as the ocean doesn’t heat up too much and the impact site isn’t close enough to you that the pressure wave from the impact cracks your sub like an egg you should be fine. One potential issue might be if the tethering stations are compromised or the cables are loosened and then ‘snapped’ taut by ocean currents, but you should be able to deal with that by having a lot of redundant anchors and actively controlling the tension of the cables. Active buoyancy control or even thrusters can also help with avoiding potential problems. At this point I’m starting to push the definition of ‘fortification’ though. Perhaps you should just take shelter on a deep ocean nuclear sub instead? ]
[Question] [ Let's say our world is set in a hyperbolic space with a curvature K of −1 per 9 square meters. How would crystals be different than those in our world (assuming that the atoms are the same as the ones in our universe)? One thing to note that on small scales, hyperbolic space is approximately euclidean. But not *exactly* euclidean. Even an atomic sized triangle will have angles adding up to *slightly less* than 180 degrees. This probably wouldn't affect amorphous solids, or organic materials, but I have a feeling it *would* affect crystals. In particular, euclidean [crystallographic groups](https://en.wikipedia.org/wiki/Space_group) would not be applicable. Well, they may apply approximately locally, but for a large crystal, it would not work for the entire structure. Now, there are probably hyperbolic crystallographic groups, related to the [hyperbolic honeycombs](https://en.wikipedia.org/wiki/Uniform_honeycombs_in_hyperbolic_space). The problem is that, unlike euclidean honeycombs, they *do not scale*. The size of the cells of a given hyperbolic honeycomb is fixed, and can be scaled up or down to different sizes. Therefore, for a crystal to take advantage of a hyperbolic honeycomb, the distance between the particles would need to match the edge length of the cells of the honeycomb. [Answer] ## Poly-crystalline crystals care not for your hyperbolic spaces If the difference between Euclidean and hyperbolic spaces on the sub-atomic scale are sufficiently small, it may not matter. Said another way, hyperbolic-isity is a macro property of this physical system instead a property of the quantum realm. The concept is similar to how Newtonian physics prevails at human scales but don't mean a thing on the quantum scale. Hyperbolic properties may only show up at human scales. Very few crystals are true mono-crystals. Dislocations, voids, discontinuities and other artifacts are exceptionally common (and downright maddening when trying to get a high quality mono-crystal). For larger crystals, these discontinuities in the crystal structure would 'absorb' any spatial irregularities at the atomic scale. To a human observer, the crystal would appear like other crystals with perhaps a higher number of discontinuities. Detecting that higher flaw rate would require specialized equipment and the knowledge that the same crystal in Euclidean space has fewer flaws. For example, a silicon-carbon lattice, shown below. Over small scales, dislocation stresses caused by the hyperbolic space won't matter since the atomic bonds can deal with some stress. Eventually though, these stresses accumulate to overcome the chemical bonds between the carbon and silicon atoms. On these boundaries, the crystal will break into a cleavage face. While this cleavage face is weaker than a normal monocrystal, it doesn't mean the overall crystal is weak in an absolute sense. [![Silicon Carbide](https://i.stack.imgur.com/acasW.jpg)](https://i.stack.imgur.com/acasW.jpg) As an example of strong polycrystaline materials, take iron. Iron-carbon crystals have lots of discontinuities and these affect the behavior of the material but they aren't visible on normal human scales. Maybe there might be a greater tendency towards smaller continuous crystals in this hyperbolic space but it would difficult to tell. [![Iron carbon](https://i.stack.imgur.com/zDKEh.jpg)](https://i.stack.imgur.com/zDKEh.jpg) ([source](http://www.foundry-sag.com/microstructures)) Also, this field is hard. I was able to find several papers on quantum physics in hyperbolic spaces but I'm not a quantum physicist so the papers don't mean much to me. Also, calculating crystal lattices is a specialized field. The software to simulate crystal lattices is very specialized. High quality simulations of a crystal lattice are extremely compute intensive. Determining the behavior of a specific crystal in hyperbolic geometry would require specific attention and lots of theoretical work to nail down. (Then you couldn't test it because we don't live in hyperbolic space.) I'd be very hesitant to make broad pronouncements about changes to the shapes of individual lattices. ]
[Question] [ Inspired by: [How much electromagnetic transmission noise does Earth have to emit to be noticeable?](https://worldbuilding.stackexchange.com/questions/124365) **Premise:** Assume that the infamous Wolf 359 star system has one habitable planet and a second, habitable or not, upon which the Wolvians have developed a mining operation. The two planets (maximum separation: 3 AU) have receivers with a -200 db threshold. The transmissions are focused between the two planets, so they would not be continuously detectable by Earth (if detectable at all) as only the signal aligned with Earth when the two planets appropriately line up could be detected. * For the purpose of this question, assume that the ecliptic of both star systems are perfectly parallel on an arbitrary X-Y axis with one another. * The Z-axis difference between the two systems should be taken into account. * Assume space between the two planets is clear of any debris. * The planets are talking with each other, not with Earth. Our detection is incidental to their activities. Please assume the Wolvians are unaware of us. * Please ignore the fact that the actual Wolf 359 star (a red dwarf) is unlikely to promote life. * Do not assume the use of satellites to get around the line-of-sight problem when the planets are on opposite sides of their sun. The transmissions may originate from planet-based transmitters or from satellites in orbit around the planets, but may not be bounced off of satellites in orbit around the sun. * Assume the transmissions from each planet are continuous such that the signals could be represented by cones, emanating from each planet in the direction of the other. * Assume the technology on Earth that is currently available to SETI. **Question:** Would the interplanetary transmissions in the Wolf 359 star system be detectable by Earth today? **Best Answer:** The best answer will consider as many of the factors complicating this premise as possible. A defensible signal strength, nature of the focus, window of opportunity for detection, all three dimensions, etc. The best answer will produce, with reasonable extrapolation from current technology, a defensible solution for what signal strength would be used by the Wolvians and its detectability here on Earth. **Worldbuilding Justification:** Building alien worlds that can be detected by Earth without *Star Trek*-ish exploration requires a better understanding of how they would justify the power needed for transmissions we can detect. Thus, from the perspective of building a civilization at Wolf 359, could that civilization have a justifiable reason (e.g., a mining operation on another planet in their own system) for pumping out the energy needed to be detected? *The linked question intrigues me because it assumes Earth would be pumping out on a general basis power levels that could be detected at very long distances. Assuming human logic (the Vogons would disapprove of that generalization), there isn't a reason to do that. There will likely never be a reason to do that. This suggests that we need an off-planet reason to pump out that kind of power — but off-planet solutions are directional, not global. Though simplified, this question suggests that the civilizations SETI's looking for are substantially more technologically advanced than we are and that the detection of their presence would strongly suggest specific applications of that technology.* [Answer] # No, because the Wolf-ians will use lasers You waste a lot of energy broadcasting a signal to anywhere that isn't your intended target. In interplanetary communications, where the distances are great, you really want to narrow your beam down. This is a job for [lasers](https://en.wikipedia.org/wiki/Laser_communication_in_space). NASA is [working on developing](https://www.nasa.gov/mission_pages/tdm/dsoc/index.html) such a system right now. If the Wolf-ians have gone through the trouble of establishing a colony on another planet in their solar system, then they will take the trouble to establish a transmission system that uses the least energy possible. Lasers are that solution (PS I know this because I just spent all weekend researching [this question](https://worldbuilding.stackexchange.com/questions/124581/how-to-improve-tcp-ip-for-an-interplanetary-wan)). So now that we are using a directed energy, point to point beam to transmit information, the chances that this beam will then intersect Earth, some light years away, is effectively nil. The Wolf-ians desire for energy savings in their transmission equipment will cause them to use a transmission medium with such a narrow beam that Earth will never find it. [Answer] Since your question states that the two planets have an elliptic parallel to the Earth's heliocentric elliptic and there's a 0.95 light-year Z axis displacement between Sol and Wolf 359 (I have a data-table with the Sol relative XYZ co-ordinates for every star within 25 light-years of Sol, if you ever need it), any signal between them won't disperse enough to be picked up on Earth regardless of strength, the light-cones aren't wide enough (assuming Earth-sized planets). If they were aiming at Sol we might get lucky; a signal from Wolf 359 is going to come in at an angle to our orbital plane of about 57.3 degrees (that assumes a matching elliptic for Earth and Wolf 359b and c), so a tight beam will miss us completely if aimed at anything but our planet directly. But you need a fairly large signal cone to even hit our solar system reliably since Sol and Wolf 359 have a total [proper motion](https://en.wikipedia.org/wiki/Proper_motion) of about 4.7 seconds of arc per year as seen from Sol, so the signal, to hit Sol reasonably reliably the signal will be 0.2 light years (12650 A.U.) across at this end of the cone. That signal should hit Earth as well as Sol, most of the time. But SETI probably can't pick the signal out of the background at that strength even if it was trained on Earth full time. Do also note that unless the aliens are deliberately using a signal wavelength that doesn't come from their parent star in any significant quantity just about any conceivable signal is going to get lost in the glare from their star and put down to natural stellar variance if it's noticed at all. ]
[Question] [ Recently, [a question](https://worldbuilding.stackexchange.com/questions/96120/anatomically-correct-charybdis) was posted about how a creature like the mythical Charybdis could evolve. Today I want to talk about Charybdis' mythical counterpart: Scylla. Most depictions of Scylla look something like this: [![It's Scylla!](https://i.stack.imgur.com/MaLJ7.jpg)](https://i.stack.imgur.com/MaLJ7.jpg) This already looks strange enough, but classical descriptions were *even weirder*. > > While Scylla was bathing in the sea, the jealous Circe poured a potion into the sea water which caused Scylla to transform into a monster with four eyes and six long necks equipped with grisly heads, each of which contained three rows of sharp teeth. Her body consisted of 12 tentacle-like legs and a cat's tail, while four to six dog-heads ringed her waist. > > > ([Source](https://en.m.wikipedia.org/wiki/Scylla#)) In this form, she patrolled the Messina Strait opposite Charybdis, snatching sailors with her many heads. Needless to say, a creature like this would likely not evolve naturally. When I saw this design, I couldn't even think about how it would move or support itself, let alone pick up a bunch of sailors. I think that the artistic depiction had a good idea with adding the front legs of the dogs to support the front of the body instead of just sticking dog heads onto the abdomen. With how Scylla is posed in that painting, her weight would crush their little windpipes. Here's my question: How can we realistically get as close as possible to a classical depiction of Scylla? I'm willing to flex and go with the artistic depiction if that helps. The only constant is that Scylla be able to snatch and eat sailors with devastating precision. Anatomically Correct series can be found [here](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series). [Answer] Let's start with Lot-Of-Malarkey's quote, rather than the artwork, which is an entirely different barrel of fish: > > While Scylla was bathing in the sea, the jealous Circe poured a potion into the sea water which caused Scylla to transform into a monster with four eyes and six long necks equipped with grisly heads, each of which contained three rows of sharp teeth. Her body consisted of 12 tentacle-like legs and a cat's tail, while four to six dog-heads ringed her waist. > > > My first question is, how would the six necks and heads come to be? Well, two-headed snakes are rare (about 1 in 10000 births might produce one, according to [this YouTube video](https://www.youtube.com/watch?v=vCuI2maEy_8). You can also check out [this article](https://en.wikipedia.org/wiki/Polycephaly)). OK, so Polycephaly is an accident of birth, the resulting creature is probably a Siamese twin, or in the case of Scylla, a Siamese sextuplet. The chance of this happening would of course be tiny, but a limited breeding pool might introduce enough mutation into the genes to make the likelihood greater. The original, un-mutated creature would have one blind head (so perhaps using something like sonar), with, four eyes (probably not very well-developed) situated on its torso (these might even be spaced around the body evenly, similar to a spider) and a mouth with three rows of sharp teeth. I would posit a creature similar to an octopus or squid, so this single creature would have twelve tentacles neatly arranged around its body. Like a squid, this creature would have a second mouth below its body, in the middle of the tentacles. The head and mouth with many teeth would be for offensive or defensive purposes, while the lower mouth would be for feeding. As mentioned previously, the number of these creatures available to breed would be tiny, probably due to the very impracticality of its design, meaning that even though they probably spawn large numbers of eggs with many resulting births, few of the young reach maturity to breed. Thus, mutation of the young would not be uncommon and Scylla is one of the more extreme results. Firstly, Scylla is actually a conjoined sextuplet, hence the six heads with only one body. The dog heads are in fact the secondary mouths, so there would be five or six, depending on whether the bottom mouth between the tentacles developed correctly. Surrounding the misplaced secondary mouths are malformed tentacles which may, from certain angles give the appearance of dog heads. Since Scylla has survived to adulthood with six heads and six brains who are probably somewhat at odds with each other, I would imagine it to be a very irritable creature. [Answer] Scylla could exist as multiple creatures, for example, they could be an aquatic cat that is surrounded by 6 eel-like fish with 2 tails and a head with eyespots in addition to eyes, as well as 4-6 bone-eating fish with dog-like heads. ]
[Question] [ Suppose you took earth and gave it approximately 3 times the air, with most of the extra being N2 or Ar. Combustion goes up with the partial pressure of oxygen. So unless we want to burn down the planet around our ears, at 45 psi, we want only 7% O2 or so. This much Nitrogen starts implying nitrogen narcosis, but we will assume that the natives evolved with this pressure, or that visitors can use medication. Three times the atmosphere will still be fairly transparent. There will be some additional heating in the air from absorption of sunlight, but the bulk will be at the surface. Tropopause will be much higher. Three times the air will mean 3 times the water vapour. Days that are now thin cloud would be heavily overcast. Heavy overcast would become dim twilight. This may reduce sunlight that reaches the surface, resulting in heating that takes place more evenly through the atmosphere. Stronger greenhouse effect? Move the planet out a few million km? Rainfall intensity could be brutal. A rising parcel of air would have much more energy available, and the density differential would be greater. This would mean either a smaller temperature differential would be needed to separate a parcel of air from the surface, and/or updrafts would be incredibly violent. With more turbulent weather, lightning would be more frequent. Updrafts could support both larger raindrops and larger hail. Being outside in a hail storm could be lethal. Wind would have 3 times the force at a given velocity. Dust would be picked up at lower velocity, and due to increased drag, would take longer to settle out of the air. Any other thoughts on the effect of air density on weather? [Answer] Actually, you wouldn't get more water vapor (unless the temperature also rose); the vapor pressure of water is dependent on temperature, not ambient pressure. The boiling point of water would be higher (just as it's lower on high mountains, with less ambient pressure) but evaporation should work as it does on Earth. The greenhouse effect would not be increased if you only add nitrogen and argon, since these are not greenhouse gases, but if all non-oxygen gases (including CO2) are increased proportionately, it would be. However, three times current CO2 levels is still less than was probably the case in the Jurassic and Cretaceous, so the planet would remain habitable (though the hotter regions might not be suitable for unprotected humans, depending on humidity levels in those areas). Hail storms... hmm. Even if hailstones were larger, they would fall more slowly (terminal velocity will be less due to the greater air resistance) so they might not be more destructive unless they were a *lot* larger. ]
[Question] [ I've been thinking about this the whole day. At first I thought it was an easy fix, given my dragon's bones have a tensile strength of 3-6.5 GPa and an elastic modulus of 50-140 GPa, depending on the reinforcing fiber's orientation. For limpets, this fiber is goethite, for my dragons, I take the risk of using carbon nanotubes. The problem here is that the extra layer, I put on top of the original pectoralis major, has to be the same length as the original (that is the requirement of circumventing the square-cube law), and needs a suitable attachment area and good leverage. Plus, it seems that the extra layer would be in the way of the downstroke. [![Bird flight muscles](https://i.stack.imgur.com/jBckv.png)](https://i.stack.imgur.com/jBckv.png) [![Bat flight muscles](https://i.stack.imgur.com/sdPd0.jpg)](https://i.stack.imgur.com/sdPd0.jpg) Of course, dragon bones don't have to look like anything you'd expect find in nature. The creation myth and thus, creationism, is an integral part of this world. Though even the gods have to obey the laws of physics. Before you say, I know it'd be easier to just increase the length of the ribcage and redesign the humerus to provide more attachment area, but I hate limiting myself. **How should the bones be redesigned to allow adding flight muscles to them (with some exaggeration) ad infinitum?** --- Some useful info: <https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0013982> <https://markwitton-com.blogspot.com/2017/01/new-paper-when-short-necked-giant.html> Note: It's kinda bad that most of these pictures don't show where the muscle ends and the tendon begins. [Answer] Why not stronger musclesinstead? Also, do they have to be made of Bone? <http://theconversation.com/scientists-create-bone-like-material-that-is-lighter-than-water-but-as-strong-as-steel-22729> The article above is a good example of how you can make it lighter. Being a dragon we're speaking of and with you willing to use carbon nanotubes in it, I assume maybe changing the composition of the bones would be a great way to make it lighter while being just as strong, if not stronger. Stronger bones are a natural must have to have more powerful muscles attached to them. Also, speaking of muscles,instead of adding more muscle, why not change the muscle composition to make it stronger? That would allow for more power without the need of changing the skeleton, as you don't wish to. Also, curiously enough, according to Wikipedia, carbon nanotube artificial muscles with paraffin are 200 times stronger than our own: <https://www.google.com/url?sa=t&source=web&rct=j&url=https://en.wikipedia.org/wiki/Artificial_muscle&ved=2ahUKEwjCv5vax6boAhWAGrkGHWLdCRAQFjACegQIDBAF&usg=AOvVaw1PqsNDiPAVsk6AmcczpASM&cshid=1584621681264> So my main advice would be: instead of looking for more or bigger,look for better. [Answer] Animal muscles are pretty wimpy in strength when compared to their mass amongst biological actuators/motors...... Check out this material. It’s called a Spasmoneme. The Ciliate Vorticella uses it to contract in response to stimuli. And it’s apparently more powerful than a V8 car engine, gram by gram. 30x time more powerful than the strongest animal muscles for the same volume. And a lot more efficient as it is driven solely by Ca2+ instead of Ca2+ and ATP together. It’s a muscle fiber with the response time of a neuron of similar size, and is directly adoptable to muscle cells as their responses to neural stimuli are the same. <https://en.m.wikipedia.org/wiki/spasmoneme> [Answer] As long as we're willing to start using advanced carbon materials, you could have monofilament tendons that extend through the body, possibly even along a joint-like pulley system. This would allow you to leverage muscle anywhere in the body to apply force. Almost any muscle could be rigged to apply force to the wings during the difficult take-off process. For very brief bursts of activity, the dragon would be incredibly strong but very limited in endurance (think hysterical strength).The bones might benefit from the ability to lock in place so the dragon doesn't have to expend any energy in flight and can operate completely as a glider once aloft. ]
[Question] [ I already have a land mask (view below) from a basic world map generator, but I need anyway that will help me place mountains, deserts, rivers, cities, etc on it. And, if possible, a height map from it as well (not so important, but if there is, just doesn't need to be all-in-one). **NOTE:** *I don't want a random generator of basic map (I already use this one <https://donjon.bin.sh/world/>), I want one that I can chose where to put surface features, cities, borders and such.* I have other land masks that are far more complicated than that, and that's why I need it. [![land mask used for a worldbuilding blog I made](https://i.stack.imgur.com/IMAeV.gif)](https://i.stack.imgur.com/IMAeV.gif) [Answer] I would use GIMP - or if you have the ability to, a trial version of Photoshop. Photoshop though would easily be my programme of choice for any raster (2D) image editing. I would use the following procedure: 1. Create Mask layer over the top of your map 2. Use your paint tool on another new layer over the top with 'Overlay' or 'Lighting' blending option. 3. Set your flow rate and radius of your brush - a slower and softer flow rate is recommended. 4. For complex polygonal mountains where you want a gradual height, use the gradient tool. However this will create a linear gradient by default - you need to change settings to make this more realistic. Might take a bit of experimenting with this to get it right. 5. Finally, apply 'Noise' filter to a new layer with a low transparency to slightly randomise your height map - Nature abhors a smooth terrain! [Answer] I'd suggest Inkscape, it works on multiple platforms and is free - with it, you can [convert your image into an vector graphic](https://inkscape.org/en/doc/tutorials/tracing/tutorial-tracing.html). You'd want to do this because it then gives you an image file that you can scale without changing image size or losing quality unlike raster images - jpeg, png, tiff etc. So scaling it 1000% bigger to add in miniscule detail becomes a breeze. Here's a [tutorial](https://upvoteanthology.deviantart.com/art/Beginner-Inkscape-Map-Tutorial-590667627) showing how to start from an image through to finished map if you're interested in seeing how it works. ]
[Question] [ By "fairies," I'm referring to the eldritch horrors and creepy-crawlies of Celtic folklore, not the glittery pixies with butterfly wings. My urban fantasy setting puts a sci-fi spin on supernatural creatures. The Good Neighbors of Celtic tradition belong to a hominid subfamily called Externinae, which predates humanity and includes banshees, gancanaghs, dullahans, etc. Early on, they adapted to life in a parallel universe, where they underwent numerous bizarre transformations. They can harness electromagnetic forces through supernatural means, which they use primarily to create illusions and prevent people from noticing or remembering them by disrupting neural activity in humans. The reason I decided to make them a group of hominids is because there's quite a bit of folklore where the Fair Folk mate and produce fertile offspring with humans, meaning there must be a close genetic relationship. I know both parents usually have to be the same species, but inter-genus hybrids exist in reality and, as evidenced by the [wolphin](https://en.wikipedia.org/wiki/Wholphin), can be fertile under very rare circumstances. Alternatively, I'm thinking of having the fairies be a genuinely alien group of organisms, some of whom have made themselves genetically similar enough to humans to allow for crossbreeding. Of course, they'd need a reason to do this. [Answer] Sure. In fact, in Celtic/Welsh/Irish lore, the "fay" or elves are fairy folk, who don't really look that different from humans, altho perhaps the have an unnatural beauty, with delicate features and perhaps unnaturally fair skin. Obviously (think Morgan le Fay) they can interbreed with humans and produce fertile offspring. Tolkien based his stories on Scandinavian myth, again with elves which are visually similar to humans and fully interfertile with them. If you want to make things more realistic, it's certainly plausible that these near-human groups are a result of divergent evolution, with humans and fairies having a common genetic ancestor sometime in the past. Perhaps the recent past, where the fay are concerned. Aliens? Well, it's not at all realistic to think that a product of alien evolution would, by a trillions-upon-trillions to one chance, accidentally produce an alien species that just happens to be a close enough genetic match to be interfertile with humans. But again, if you really want to, since it's your world, you can just wave the wand of magic over it and proclaim them interfertile because magic enables them to be. But divergent evolution in geographically isolated groups, such as /Homo floresiensis/ (so-called "Hobbits"), is much more plausible. Moving to less human fairy folk, there are an astonishing varity: Brownies, gnomes, goblins, dwarves, nixies, pixies, dryads, mermaids, kobolds, lebrechauns... I have a book entitled THE WORLD GUIDE TO GNOMES, FAIRIES, ELVES, AND OTHER LITTLE PEOPLE. An astonishing variety of elves and "little people" in various cultures around the world; 556 pages. Bigger differences suggest larger genetic differences, hence lower chances for interbreeding. And if you want to keep things realistic, don't make them as small as pixies (i.e., Tinkerbell). They need to have a large enough brain mass to be intelligent. Some anthropologists argue that /H. floresiensis didn't have a large enough brain to be intelligent, but others argue they were sapient. So if you want to keep things realistic, don't make them smaller than "halflings". Of course, since it's fantasy, you can simply handwave that restriction away and say "magic lets Tinkerbell be sapient", if you want. It's your world! [Answer] I'm going to avoid categorization and the messy issues of the supernatural (un-explainable), mating, love, lust and other less wholesome alternatives - I'll leave that to those who are more expressive, capable and brave than myself - and go with one of the fundamental tenets of science fiction, [Arthur C. Clark's Third Law](https://en.wikipedia.org/wiki/Clarke%27s_three_laws), which states that "any sufficiently advanced technology is indistinguishable from magic". A culture that has full competence over genetic engineering would be less encumbered by notions of speciation (thought they may still acknowledge differentiation among groups of organisms) - to a sufficiently advanced culture, a species is nothing more than a blue print with certain characteristics, perhaps unique, but regardless, trivially exploitable. This could perhaps explain your numerous bizarre transformations. In any case, mating would not be a hindrance to any form of recombination with other organisms. As for the specific question, "could [faeries] be a hominid subfamily" - it's your world, they could be anything you want them to be. I tend to base my creative decisions on what I know is possible first, then deal with details later. This frees me from going down the slippery slope of inventing everything from scratch and trying to make it cohesive, and it is a way of being able to back track later without being distracted in the moment. If there is not enough structure to keep the flow, then I can simply go and read on the topic and what relates to it until pieces start fitting together and everything begins to flow again. [Answer] Maybe you are thinking of the hominids found on the island Flores termed [Hobbits](https://en.wikipedia.org/wiki/Homo_floresiensis) in popular literature. It is indeed fully conceivable to have other hominid species coexisting with Home sapiens at the same time. What supra-natural powers are concerned, I am very skeptical: It is rather safe to assume that other hominids don't acquire powers that no species in the world has ever acquired. Such creatures are always phantasies, I'm afraid. [Answer] I don't see why not. Making fairies is a sub family of humans makes sense. Alternatively you could make them descendants of humans who were genetically mutated by the supernatural energies in this parallel universe. [Answer] In one version of the Muintir Nemed (hope I said that right) people of Ireland, some left and became beings such as the Fir Blog or other peoples, and those who stayed became the Tuatha de Danann. Who then become the Sidhe. So by technical standpoint in Irish myth a species of fae does share a common ancestor with one particular race of people ]
[Question] [ ## Which solvent to use for metal nerves? Based on [this answer](https://worldbuilding.stackexchange.com/a/27124/10364) on to how to evolve biological radios, the answer states that if creatures in an ecosystem utilize metal for electrical transmission instead the sodium-gate depolarization system used on earth, they would enjoy a considerable speed advantage. Water will dissolve [sodium](http://www.lenntech.com/periodic/water/sodium/sodium-and-water.htm), and [potassium](http://www.lenntech.com/periodic/water/potassium/potassium-and-water.htm), both used in the [operation of nerves](http://health.howstuffworks.com/human-body/systems/nervous-system/nerve4.htm). This works well on Earth. But, we aren't on Earth anymore, we are somewhere else; somewhere that the creatures of this place use metals for their nerves (nerves of steel, if you will) instead of sodium and potassium. ## Question * What is the best metal+solvent combination to use for a metal nervous system? * How likely is this solvent to be freely available in an ecosystem? Ideally, the metal+solvent pair should not be incompatible with biological systems of the same complexity we see on earth though this need not be proved in your answer. ## Scope The design of the surrounding ecosystem is outside the scope of this question. The design of the creatures that would use metal nerves are also outside the scope of this question. We don't care what they look like or how they move. We just care about what they would need to eat and drink to support a nervous system based on metals. [Answer] I'm not sure we need to discuss solvents in this answer. [This article](http://news.discovery.com/earth/weather-extreme-events/gold-bacteria-nuggets.htm) shows that humans found a bacteria that extracts gold from its environment and then coats itself with it. If we extrapolate this ability to a eukaryotic being's nerves, then we could get nerve cells coated in highly conductive metals (probably copper - since it's more available and already used in the body). Once these cells are coated in a highly conductive material, it's easy to see that any electrical impulses passing through that cell will preferentially travel the path of least resistance (through the metal exoskeleton). The problem is, [most of the delay in nerve transmissions are due to the signal jumping the gap between cells](https://en.wikipedia.org/wiki/Electrical_synapse#Effects) and NOT the electrical impulse traversing the cell. > > Without the need for receptors to recognize chemical messengers, > signal transmission at electrical synapses is more rapid than that > which occurs across chemical synapses, the predominant kind of > junctions between neurons. The synaptic delay for a chemical synapse > is typically about 2 ms, whereas the synaptic delay for an electrical > synapse may be about 0.2 ms. However, the difference in speed between > chemical and electrical synapses is not as marked in mammals as it is > in cold-blooded animals > > > I think you would see improved reaction times but not by a huge amount. [Answer] * Both potassium and sodium are both alkali metals. Done. * Electrical conductivity of metals relies upon their crystal structure. When dissolved, this stops to work. Steel dissolved in anything would perform as badly as sodium/potassium/chlorine dissolved in water. [Answer] In a metal on earth, electrons travel because of an electromagnetic wave. So in your world, a "solvent" for the nerves of steel could be an electromagnetic wave, or perhaps an "ether". ]
[Question] [ Earth has an iron-nickel core which gives us a magnetosphere. **Based on [this question](https://worldbuilding.stackexchange.com/q/27277/10364) that replaces our iron core with a mercury core, would we be likely get a magnetosphere?** Mercury is highly conductive and forms mercury(Hg ii) crystals at high pressures. At low temperatures and high pressures it becomes superconductive. Given the conductivity, mercury *might* form a magnetosphere but I'm just not sure. What happens to the crust or how life might form on such a planet is outside the question scope but if you'd like to speculate on these topics or on how the planet was formed, you are welcome to do so. [Answer] Considering this is world *building* site instead of physics/astronomy (as pointed by Rob Watts), I would try to give an explanation that is best to my knowledge (but might not be very precise or accurate, as I am not a professional astronomer). The magnetic field of an astronomical body is linked to the [presence of electrically conductive fluid](https://en.wikipedia.org/wiki/Earth's_magnetic_field#Physical_origin), so Hg would do the trick assuming it supports suitable convection cells. Now there's one thing that needs to be pointed out immediately. We do not know what form mercury would take under extreme pressure. To understand what I mean, you might want to read about [ice phases](http://www1.lsbu.ac.uk/water/ice_phases.html) of common hydrogen oxide (water). Under extreme pressures, ice starts to take the form of crystals (very unexpected thing for ice!). Similarly, we don't know what form mercury would take in the core of a planet. Depending on the size of core, the planet might get distorted out of shape if it is spinning above a threshold angular velocity as the crust would give in and crack due to the enormous pressure of circulating mercury core (atomic mass 200 versus iron that has atomic mass 56). I think it would be a horrible scene to behold, even looking at it from million miles away! As for life, well, I don't know why would life forms be any different from what they are on Earth **except** that the magnetosphere plays an important role in the formation of organic molecules. ]
[Question] [ I'm working on a tabletop roleplaying game about witches. I have most of the mechanics of broomsticks worked out, but I'm having trouble deciding on top speeds. Speed limits are not a result of how fast the broomstick itself can be made to go, but are imposed by air resistance ripping the witch off the stick at high speeds. I'm looking for two speeds; one for witches sitting sidesaddle, and one for witches astride the broom. Novice witches sit sidesaddle, because it's easier to balance that way, whereas more experienced witches sit astride it. Sitting astride the broom allows them to bend forwards and better streamline themselves, as well as giving them a better grip. Other facts that might be pertinent: The lift occurs entirely in the broomstick, and the witch must rest upon that. The broom are ridden bristles-backwards. For the purposes of this discussion, the witch is performing no magic besides the magic that lifts and moves the broom. Assume that the witch has just enough practice to balance on the broom, but she is by no means an athlete. Her grip strength, weight, and so on are average for humans. How fast can she go without being ripped off by the oncoming air? [Answer] Not the answer you're looking for: I believe the answer is that it's effectively impossible. For drag itself your limit is going to be drag vs grip strength. I believe your witch will be subject to their own weight at something around 140 mph, drag goes at the square of velocity. However, you're gripping the broom in a very inefficient way. Note that you can test this yourself (but see my second point!!)--clamp a strong broomstick between two supports, wrap a rope around your chest, then over something behind you so it dangles down. How much weight on the rope can you resist? However, there's a far bigger problem here--how are you going to sit on that broomstick in the first place? Your center of mass is above the broomstick, the broomstick is round. You're going to have a major problem avoiding rotating around the broomstick. (Note that this could be overcome by strapping enough weight to your feet, but the weight needed is considerable.) ]
[Question] [ **This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. I've seen a couple questions before (like [this one](https://worldbuilding.stackexchange.com/q/56643/6781) and [this one](https://worldbuilding.stackexchange.com/q/55875/6781)) that ask about the habitability of a planet, with a key part of that being if the atmosphere is survivable. It seems like we should have one question that covers all the basics of atmospheric habitability. So, **what does the composition of an atmosphere need to look like in order for it to be suitable for life as we know it?** Which gases *need* to be present, and in what concentrations? Which gases can be present without significantly affecting habitability (other than not leaving enough room for necessary gases)? Which (common) gases should not be present in significant amounts? Keep in mind that for a lot of gases, it is the [partial pressure](https://en.wikipedia.org/wiki/Partial_pressure) that is important. For example, at 1 atm you should have at least 16% and (much?) less than 60% oxygen in the atmosphere, but at 0.5 atm you'd need 32% oxygen as the minimum (and 100% oxygen might be safe long term?) [Answer] Okay, so this is going to be long, so I apologize in advance and if I screw up anywhere, please feel free to point it out to me as I'm not totally an expert in this, I'm just applying what I know. So the first thing to note is that the composition of an atmosphere is highly dependent on the life-forms that use it and vice-versa. (For us Humans, we need Oxygen, it's about the *only* element of our atmosphere that we actually use in day-to-day life) Which means we really need to talk about the ecosystem in play. Plants use Photosynthesis, which converts Carbon Dioxide and water into Oxygen and Glucose(sugar) via the following method: $6CO\_2 + 6H\_2O → (Sunlight-and-Chlorophyll) → C\_6H\_{12}O\_6 + 6O\_2$ Plants, along with other lifeforms also use respiration, which actually uses the reverse equation, which does not require Chlorophyll or Sunlight: $C\_6H\_{12}O\_6 + 6O\_2 → 6CO\_2 + 6H\_2O$ Next, we need some way of creating lifeforms, this generally requires Nitrogen (For Amino Acids, proteins, and genetic material) and is why our own atmosphere has such a high percentage of it, despite not being needed for the above processes. Instead the Nitrogen Cycle is used as follows: Method 1: Lightning Fixation (Note: No known amounts, Please fix if you know) $N\_2 + H\_2O$ + $\mathrm{e^-}$ → $NH\_3 + NO\_3$ Method 2: Biological Fixation $N\_2 + 3H\_2 → 2NH\_3$ Now that we've got our Ammonia and Nitrates, we can continue through the Nitrogen Cycle to Nitrification as follows: $2NH\_3 + 3O\_2 → 2NO\_2 + 2H^+ + 2H\_2O$ and then $2NO\_2^- + O\_2 → 2NO\_3^-$ Plants utilize the nitrate as a nutrient. Animals obtain nitrogen by eating plants or plant-eating animals. When plants and animals die, bacteria convert nitrogen nutrients back into ammonium salts and ammonia. This conversion process is called ammonification, which then is followed by denitrification, which completes the cycle as shown below: $NO\_3^- + CH\_2O + H^+ → ½N\_2O + CO\_2 + 1½ H\_2O$ So, we've actually listed our main requirements for life on Earth already, even if unintentionally from these processes. 1. Nitrogen ($N\_2$) 2. Oxygen ($O\_2$) 3. Water ($H\_2O$) 4. Carbon Dioxide ($CO\_2$) Now we know what makes up life as we know it, it's time to answer the second part of your question, concentrations, specifically how much concentration is needed for life, as we know it, to flourish. ## It doesn't matter Let me explain, as long as you've got some amount of all four of these elements mentioned above in your atmosphere you'll find that life can and does survive. Recreational Divers use Enriched Air Nitrox, which contains a higher percentage of Oxygen to regular air, 32% and 36% are common; and some technical divers use anywhere from 50% to 80% Oxygen as a decompression gas due to its lower partial pressure of inert gases (More info [here](https://en.wikipedia.org/wiki/Nitrox)) ## However Too high an Oxygen concentration will kill, as will too low an Oxygen concentration; which is why Pure Oxygen (100%) is strictly restricted and has limited uses ([See here](https://en.wikipedia.org/wiki/Oxygen#Medical)); and why going up mountains without air tanks is incredibly stupid and dangerous. (Over 7,000 feet (2,100 meters) is considered risky, as oxyhemoglobin saturation levels plummet and over 26,000 feet (8,000 meters) is considered the "death zone"; though anywhere over 11,500 feet (3,500 meters) is considered to be too dangerous for untrained humans to breathe in) - [More info here](https://en.wikipedia.org/wiki/Effects_of_high_altitude_on_humans) ## In Summation I would recommend any potential, budding WorldBuilders to seriously consider what kind of world they are building and what kind of lifeforms they wish to inhabit its surface before trying to take atmosphere composition into account, as these figures and compositions are for Life here on Earth and may be different for other Life that we, Humans, are unaware of. ]
[Question] [ Assuming the axial tilt of the Earth was increased to roughly 30°, and the orbital eccentricity roughly doubled(0.03 as opposed to 0.016) so that the average temperature stayed the same, but the summers became hotter, the winters colder and the seasonal changes from latitude became more extreme, what kind of weather differences could be expected? I'm building a world that is very Earthlike other than the changes mentioned above and I'm having trouble figuring out how it would affect the weather on the planet. I know that the seasonal extremes would cause more severe storms, maybe even the theoretical hypercanes, but I am not very well versed in meteorology, let alone climate models for an entire planet. I've seen plenty of questions about the planet having no axial tilt, but mot a ton about a slightly higher tilt. I did find several Quora answers that are almost exactly what I was asking: <https://www.quora.com/If-the-Earths-axial-tilt-increased-to-30-degrees-what-effects-would-it-have-on-Earths-climate-zones> The only problem is that there is almost no talk of how weather would be affected, as most of the answers are about how it would affect Earth. All I'm really looking for is the expected changes to the yearly weather. Would there be increased rainfall in the summer? Why's that? Would the northern winters be non-stop blizzards? No? Alright. Just a basic rundown. Any help or advice on where to start looking would be appreciated. P.S. I understand that weather is an incredibly unpredictable and complicated subject, and that I'm making a highly theoretical model here, so perhaps just some guesses based on the fact that summers are warmer, winters are colder and the poles experience more intense variations. **Thanks!** [Answer] **Warmer overall, no polar ice caps, with extreme seasons at high latitudes; possibly wetter as well** Essentially, this hypothetical is an extreme case of the Milankovitch cycles in real life, which drive Earth's ice ages (glacials/interglacials). There is a ~100,000 year cycle of varying orbital eccentricity and a ~40,000 year cycle of varying axial tilt. (NASA page: <https://climate.nasa.gov/news/2948/milankovitch-orbital-cycles-and-their-role-in-earths-climate/>) Actually, 0.03 eccentricity is well within the range of the RL Earth over geologic time, though higher than the current value; according to the linked NASA page, it varies from 0.0034 to 0.058. The real game-changer here is the 30-degree tilt (vs. 22.1 to 24.5 in reality). Per the linked page, "Larger tilt angles favor periods of deglaciation (the melting and retreat of glaciers and ice sheets). These effects aren’t uniform globally -- higher latitudes receive a larger change in total solar radiation than areas closer to the equator." So with this very large tilt angle, Earth probably loses all glaciation (due to warmer polar summers). Ice is very reflective, so this Earth will receive more solar energy, and be somewhat warmer overall. All that water from the polar caps will be "available" in the water cycle as well - so sea levels will be much higher, and it may be rainier. [Answer] Cooler than Earth yes, but the Southern hemisphere would tend to experience very warm summers and very cold winters to an even greater extent than our southern hemisphere already experiences. ]
[Question] [ Many alien worlds will most likely be water worlds. I was wondering what the deepest possible global ocean dept is where land is still possible. I think that volcanic islands will still have a chance to form even after continents are no longer possible since they can have quite steep slopes which are supported by water. I'm aware that this isn't anything we can describe easily, so all I'm looking for is **a rough estimate**. Would there be any reason not to scale this estimate linearly with gravity to adapt it for worlds with nonterran gravity? [Answer] On Earth, the deepest point in the ocean is [Challenger Deep](https://oceanservice.noaa.gov/facts/oceandepth.html) (36,200 feet) and the tallest mountain is [Mount Everest](https://oceanservice.noaa.gov/facts/highestpoint.html) (29,029 feet). Mount Everest is roughly 65,000 feet taller than Challenger Deep, so if you parked the two next to each other and raised the ocean levels to just below Everest's peak (RIP life) you could have an ocean more than *12 miles deep*. There's no hard and fast reason that the difference couldn't be even greater in your fictional world. ]
[Question] [ I'm about to (re)start an effort to collaboratively create a complete world. I'm afraid most ideas would be mine, but I really want it to be open for others to contribute. I'm seeking for an Internet-based platform (most preferrably via browser) to do that. So far I can think on a wiki and on Kune, but I need something that is really easy to use, and that can give a formatted book as an output (not necessarily in an automated fashion). Required functionality is: 1. Collaborative 2. Web based 3. Ability to include texts and images (maps and illustrations) 4. Easy to use 5. Somehow secure (not allowing a bad-faithed collaborator to delete all contributed material) [Answer] I suggest to use some concurrent versioning system like CVS, SVN or GIT. These are used by software developers to write program texts and are freely and readily available on [GitHub](https://github.com/), for instance. They already support all needed security and can be quite user friendly (see [overview](https://git-scm.com/downloads/guis) of user friendly interfaces). They allow to setup the following development process: 1. A new contributor makes a branch (new version) of the mainstream (*trunk*) World description that has some text added, removed or changed. 2. A contributor opens *pull request*, maybe additionally describing that changes are made, and why. 3. This pull request is visible on the web in a *diff format* (only showing that has been changed). This allows to view and review differences very efficiently, without the need to read through lots on unchanged material where changed parts may be overlooked. 4. If community agrees that changes are good, a branch can be merged into trunk. Normally there are many pull requests opened and under discussion at the same time. The most important feature of these versioning systems is that multiple contributors can make changes in parallel inside the same text document, as long as changed parts do not overlap. If one pull request contains rewrites near beginning and another near the end, these can be submitted, discussed and merged or rejected independently, in any sequence. Merging is only supported for the plain text. Versioning systems also support binary files like images, but cannot merge multiple independent changes, the latest version just overrides all others. [Answer] While asking a similar question myself someone recommended [DokuWiki](https://www.dokuwiki.org/dokuwiki) and I've been using it almost exclusively since. * It's a wiki format so it's easy to add formatted information/images * You can install it on a website, pendrive or Dropbox and grant access to just your collaborators * Pages/links make your documents much more structured than a shared single document * It supports versioning of pages you've edited * It's free * It supports its own user account (if Dropbox security isn't enough for you) Personally I would recommend downloading the pen drive version and copying it to Dropbox, you could always arrange hosting somewhere but it would be more complex and probably end up costing money (unless you want to simply grant access to everyone and use something like [wikia](http://www.wikia.com/Wikia)). In short I agree wikis are a great way to go. [Answer] [GoVisually](https://govisually.com/) is a possibility. You can mark annotations and place comments on any part of your project, and there is this pretty cool feature where you can click on each user and it will hide or display relevant content, so if you think some user is just trolling around you can ban him. Revisions can also be easily upload and it's simple to switch between different versions of the same document or project. And I'm not entirely sure, but I think it's still free. Here's a promotional video I found on google: [Video](https://vimeo.com/212361350) [Answer] **There is no such thing, yet** to even make something like this would require there to be some way to format/organize this. As far as I know Ive never heard of a standardized structure to world building and if there is it must be annoyingly complicated and overly rigid. Thus at this point you gotta use some kind of generic collaborative document generation tool.......like google docs. Great thing about google docs is it has version history so if someone flips the table on your project you can just revert their changes. > > 1.Collaborative > > > google docs > > 2.Web based > > > google docs > > 3.Ability to include texts and images (maps and illustrations) > > > google docs > > 4.Easy to use > > > google docs is a google product, just about one of the few companies with a significant track record on ease of use. > > 5.Somehow secure (not allowing a bad-faith collaborator delete all contributed material) > > > on google docs you can whitelist your contributors preventing some troll from showing up and wrecking everything. You can also revert changes using the revision history. > > and that can give a formatted book as an output > > > Sure google docs can do that too....though again the formatting is going to be on you. --- **I only suggest this next thought because it would be such a proper, fun even, way to really collaboratively attack building a world.** Now if you want a real approach to collaboratively building a world. You can repurpose an agile tool like JIRA, plot your high level target world ideals as epics and pose research questions as stories that you pass off to willing team mates that link to a google doc where the answer is built. This way you organize and distribute your world building in a trackable way. providing this kind of structure would actually stimulate and focus collaborative effort. The down side is if you are unfamiliar with agile and agile tools this would be a pain in the ass to figure out. [Answer] If you just want a document that others can easily edit, a shared Google Drive document might do. Just be wary of people going in and deleting everything (don't give the public full access, only your collaborators). ]
[Question] [ So imagine people were the size of house cats, and the world's land masses were scaled down accordingly (in volume). In comparison to the original size of the landmass, how big would England be? And how would the scaling down change the climate of England? An image example would be nice for visualization, or an equation would be helpful, but is not required. [Answer] There are a lot of answers that describe size if humans *were* cats, but from what I can tell, you want humans to be the same *size* as cats. If we assume the average human is 6 feet tall, and the average cat is about 18 inches, that means a cat is about a quarter the size of a human, at the longest length, not counting the cats' tail. England (or rather, the island of Great Briton) is 300 miles across, and 600 miles long. Reducing by a quarter for the new human proportions, that would make the Island 75 miles across and 150 miles tall, reducing its area from 80,823 square miles to a mere 5,051.4 square miles. Assuming this new England were in roughly the same location, and the rest of the world remained roughly the same, the weather would be somewhat as if you took the first hundred miles of coastal area and threw away the middle bits. Scotland would be barely above sea level; any storms that came through would be much, much worse! [Answer] **Size by mass is not the same as size by 2d footprint** There is a cat here. She weighs about 5 lbs. I weigh 200 lbs, rounding to nearest 100. Cat is 1/40th my size. A sack the size of me could hold 40 cats, tightly packed by someone besides me. England is 50,000 square miles. Divided by 40 is 1250 square miles. Long Island in the US is 1401 square miles. So you might have an England the size of Long Island. That said, one could also look at 2d footprint. The cat and I occupy a similar amount of space on the ground; I just stick further up into the air. [Feral cats have ranges on the order of 1-2 square miles.](https://www.smithsonianmag.com/science-nature/the-secret-lives-of-feral-cats-179790776/); a human hunter might range over a similar area. In this comparison of space occupied by a cat as compared to a human, you might want an England-sized England for your cat sized people. [Answer] People are already cat sized. There are machines that People have bred to provide food for People... those machines are called “humans” (in the machines’ own tongue). The scale of England need not change because the People are already its rulers. [Answer] Cats are imperialists, they purr and lull you into a defenseless state. They put up with us because we feed them. Given a choice, cats will take England just the way it is and humans can have that other place you want to give them. Go stuff the humans there, but leave the cushions and food. This means England stays the same size and the weather may improve, as cats now own it and they have connections. [Answer] **Roughly 50,000 square miles.** Did you know that the length of a 'foot' differed quite a bit - [ranging everywhere between 9 and 16 inches.](https://sparkfiles.net/foot-whats-special-12-inches) But ultimately, it was a measurement that was designed based off a person's size-of-foot. Did you know that the mile has been defined both by "number of paces" and "number of feet"? [It gets its name from the Roman 'Mille Passus'](https://www.britannica.com/science/mile) - or '1,000 paces', but is currently defined by 5,280 feet. All of this is to say: if human being were the size of cats? And the land masses were shrunk down similarly? Then it'd all still be the same number of square feet and the same number of square miles! Because those measurements are based on the scale of a human. Which means the answer is simple: it's the same 50k square miles it is now. For what it's worth, this attribute of universal standardization (uniform across all hypothetical human sizes) is why scientists have generally abandoned the metric system and have gone imperial. :-) [Answer] This is an excellent and sophisticated question. There would be many, many ways to think about this, such as conservation of energy, material science (you can *not* just slim down materials abstractly, issues of tensile strength, laminar flow etc, become critical), farming and food production, and so on. Just one interesting issue which would need to be examined is the extremely **highly variable** ratio of cat groundspace in different postures, compared to humans who are generally upright except when sleeping. # Comparing cat to human as such is simply misguided. The best calculation would be to compare the size of a typical **cat house** to a typical **human house**. If you think of quaint London terrace houses, I just googled the typical **width** of the street frontage is about **6 meters**. Now, picture an imaginary cat house, such as in the film *The Cat Returns* where our heroine shrinks down to a world of cute little cat-size houses, # Compare house sizes. [![enter image description here](https://i.stack.imgur.com/Y7tGV.jpg)](https://i.stack.imgur.com/Y7tGV.jpg) [![enter image description here](https://i.stack.imgur.com/41pCY.jpg)](https://i.stack.imgur.com/41pCY.jpg) [![enter image description here](https://i.stack.imgur.com/GWtdu.jpg)](https://i.stack.imgur.com/GWtdu.jpg) Cat fanciers will be able to answer the question, **about how wide would a cute little cat-house be**? Let's say one meter across. (It could be more like 1.5 .. I don't know. The worldbuilder, or some cat fanciers, would decide this.) Let's use a calculator to divide 6 by 1, it turns out # Cat Britain would be 1/6th the size of actual Britain In fact, Britain is conveniently 1000 km long and 500 km across. So the actual answer to the question is # Cat Britain is 160km long and 80 km across. So that's it. Note that issues of volume, weight etc are totally irrelevant. UKCat would have cat-cars, cat-skyscrapers, cat-trains, cat-roads, cat-Tescos, cat-Brexit and so on. You simply have to decide on how wide a cat-terrace-house would be compared to a normal-terrace-house - I've said "one sixth" - and you have your answer. [Answer] # Actually... If people were cats, then people would want a BIGGER Britain. A typical cat - *Felis silvestris cattus* (Fsc) - is often compared but not necessacily a derivate of *felis silvestris* (Fs) - the european wild cat. Both demand territories. Territories for domestic *Fsc* range from 0.07 to 0.28 km², those for *Fs* range from 1 to 8.7 km². Let's take the middle as an average. That gives 0.17 km² for *Fsc* and 4.85 for *Fs*. Ferral *Fsc* demands territories similar to *Fs*. 24% of the UK human adults are adopted by a cat, for about 10.9 million house cats. Add 0.9 million ferral cats that chose not to adopt a human or lost theirs and 2000 *Fs*, mainly in Scotland, that hold up ancient tradition to never adopt humans. That's the general cat population, so we can assume this will be the population of people, or otherwise we'd need to house 66.44 million people. Each of the people shall get their proper territory as it would be natural: * 1.8375 million km² for the housecats * 4.3650 million km² for the ferral cats * 0.0097 million km² for the wildcats That's not all the cats in the UK though! Let's look into the zoos what other cats get their share of the UK... for example if we take just the [ZSL report](https://www.zsl.org/about-us/list-of-animals-and-animal-inventory) we have to also accomodate for these inhabitants of the London and Whipsnade Zoo: * 6 *Panthera leo* * 4 *Panthera leo persica* * 2 *Panthera tigris sumatrae* * 5 *Panthera tigris altaica* Add to that that in all, England had [in 2018](https://www.express.co.uk/news/nature/1000220/mapped-Lions-tigers-bears-living-near-animals-nature-Britain) the following big cats in *private* homes "13 leopards, three cheetahs, nine lions and nine tigers" - We need to allocate extra territories for 2 Lion Prides (20 to 400 km²), 9 loner lions (600 km²+), 3 cheetahs (40-80 km²), 13 leopards (10-500 km²) and 16 tiger (60-100 km²). Taking the upper as food in england is not abundant but somewhat scarse, these few bigcats get a share of 1.754 million km² (or 7 times GB), but that's only England's statistics, so we double them for Scotland, Wales and North Ireland. So, all in all, our people demad 6,247,280 km². But Great Britain only supplies 242,495 km², so we have to **increase** Great Britain's size by a factor of close to 26 to house all people comfortably. If we however just turn all the 66.44 million people into housecats, we'd need 11637000 km², or 48 times Great Britain, if their former housecats vanish, or 13534500 km² if those stay but the other cats are expelled. 55.8 times GB. [Answer] Hm going by rough length I would go from wikipedia - a "mid-sized" cat to have shoulder height of 0.3 m , a "mid-sized" man around 1.8 m .. so divide length by 6 - and squares by 36 .. Going from Great Britain (island)'s area of 219.331 km² .. gives ~6100 km². If I assume the same length "translation" to your fantasy planet, gives a roughly 2200km diameter planet (earth ~12750 km) and your fantasy "little britain" around 950 km from the equator (instead of ~5890 km on earth). If such a planet could exist in orbit at earths position it wouldn't change the climate since your fantasy planet would have a steeper temperature gradient between equator and poles ... ]
[Question] [ My world is roughly the same as the middle ages but has a natural form of birth control in the form of a root that can be grown and consumed to prevent pregnancy. Because of this root, opportunities to receive education have opened up to those women who can afford it. However, birth control and access to education for women have historically been associated with a sudden and dramatic drop in birth rates. For lore reasons the population needs to be relatively high similar to what it was during the middle ages. Is there a reasonable explanation for why the population wouldn't drop despite having access to birth control? The birth control root, while not cheap, is not expensive either. Definitely affordable to the noble and merchant classes, and to lower classes to a limited degree. [Answer] There are a lot of comments now and I won't read them all so sorry if I repeat a few things that were said but here are my two cents. 1. There were forms of birth control in the middle ages and long before which probably would have worked to a similar extant you describe yours. Therefore, I don't think you even need to acknowledge this. 2. The number of kids who die is a big factor as opposed to birth control alone; people are willing to have less kids if they know they will all (likely) survive. Therefore people in your world might be more likely to have less kids if there is other medicine and child mortality goes down. 3. If you still feel strongly that this needs to be explained, which I don't think it needs to be, you can perhaps think about what causes high birth rates in Israel which has by far the highest birth rate amongst OECD countries. Some factors that contribute to this are likely religion (which says you should be fruitful and multiply), baby boom to replace people who were killed in WWII, and flexible work life and a lot of help with kids from family encouraging women to have kids and continue living their lives. [https://www.taubcenter.org.il/en/research/why-are-there-so-many-children-in-israel/#:~:text=People%20often%20mention%20two%20factors,children%2C%20reduced%20working%20hours%20following](https://www.taubcenter.org.il/en/research/why-are-there-so-many-children-in-israel/#:%7E:text=People%20often%20mention%20two%20factors,children%2C%20reduced%20working%20hours%20following) [https://www.thejc.com/lets-talk/all/the-riddle-of-modern-israel's-remarkably-high-birth-rates-2d3Ch8U5grh4kAYH42j7sR](https://www.thejc.com/lets-talk/all/the-riddle-of-modern-israel%27s-remarkably-high-birth-rates-2d3Ch8U5grh4kAYH42j7sR) [Answer] # A Lack of Birth Control Wasn't the Cause of Large Families As one commenter already pointed out, the reason people had large families in the Middle Ages wasn't because they couldn't avoid it; rather, it was a combination of factors: * The desire that enough of one's children would survive to adulthood despite the [enormous infant and childhood mortality rates](https://www.thoughtco.com/medieval-child-surviving-infancy-1789124). * Particularly in rural settings, the desire to have people to work and inherit the land. * A nearly complete lack of rights for women. The availability of birth control doesn't matter if the lord of the manor wants to sire a dozen heirs. You've already indicated that the root would be an *expense* for peasants, and the population growth in the Middle Ages was not led by the nobility or merchant classes. Also: > > Because of this root, opportunities to receive education have opened up to those women who can afford it. > > > Unless your culture is very different than the European middle ages, again, childbirth/motherhood was not the principal obstacle to women being educated. [Answer] You've missed the other great factor in plunging birth rates, and that is the death rates. If birth rates were the only factor, why did overall population growth remain flat or very low throughout thousands of years before industrialization happened, even with birth rates far above what we see in first-world nations today? **Life Expectancy:** Historically, life expectancy figures have been far lower than in modern times. However, this is because the statistics commonly expressed in this comparison are for *average* life expectancy; there's a separate measure for *maximum* life expectancy (which is what many people think of in practice), which is essentially defined as the average across the top 10% of longest-living people, so it's only really considering people who survived to be old. People die long before reaching old age for any number of reasons, which drops the average significantly if they're common enough: accidents, warfare, disease, the list goes on. The trick here is that the gap between average and maximum life expectancy is much smaller in modern times than in pre-industrial times. Historically, people who lived to adulthood had very good odds of surviving to reach 60 or 70 (even warfare usually took only a small percentage of the male populace away, as most had to keep working the fields), despite average life expectancy usually being 40 years or less. This is almost entirely due to infant mortality rates. Before the industrial age, half or more of babies didn't survive their first five years. **Those high birth rates throughout most of history don't mean that the babies all grew to be adults and started their own families. A family would often have five or six children just to see two survive to maturity.** Royalty and wealthy families (who tend to get more of the detailed attention in historical records, naturally) might have been prone to having more survivors, but they had access to the best food and medical care, so of course they'd beat the average. **Replacement Rate:** In nature, birth rates and death rates over the long term typically balance out to keep a population stable: temporary distortions are inevitable, but persistent deviations towards extra births mean an expanding population, which requires more territory, more food, and more resources in general. The "replacement rate" (the rate of births needed to maintain that equilibrium in a given environment) is generally close to the actual birth rate: the post-industrialization population boom happened when death rates plunged very quickly and our instincts and society didn't catch up. In modern first-world nations, this is about 2.1 births per female (a rate lower than 2 is impossible for humans, assuming equal numbers of both sexes), since infant mortality is very low, random car crashes and the like kill only a tiny proportion of all children, etc., so nearly everybody will have their chance to have children. In older times, when a much smaller share of children survived to reproduce, that necessary replacement rate rose accordingly. For my part, I don't think that education of women was the main factor in cutting down birth rates: not that that isn't a relevant factor, but I would put it third in line at best. The rise of sanitation and food security are the two big ones. With sanitary improvements (and medicine in general, but proper sanitation and cleanliness were key), infection and disease plunged, which means a lot less infant mortality. Food security is also crucial, because in medieval societies one year of drought often caused severe famine, thousands of dead from starvation, possible societal collapse, etc. With improving supply networks, large-scale food preservation, and so on, shortfalls from one area could be covered by a surplus elsewhere, ensuring a reliable yearly minimum of food high enough to actually feed everybody. Education might have dropped the birth rates, but sanitation and food security are what allowed society to survive those drops. **Conclusion:** Frankly, I don't see your birth control being used all that much in a medieval society. Some would, certainly, but regular users would form a small proportion of the overall populace, because you'd still be losing a lot of children to the various causes of infant mortality, and so you'd need to have more children to replace those that died. There's absolutely individual cases where birth control would be desirable, but in the big picture they would be a minority. Also, you've noted that your birth control is expensive enough that the lower classes have "limited" access to it, which means it's too expensive to be used continuously by the largest segment of the population. Peasants and farmers would be putting spare funds into simple survival, because medieval societies didn't reliably have a surplus; they can't afford to waste money on what is effectively a frivolity when they're trying to make sure their children are fed. [Answer] In a medieval setting, you would *want* to have the highest possible population because it was **profitable**. For peasants (i.e. the vast majority of the population) children were probably the best investment available to them, and could start contributing to the household's economy at (what seems to us) a surprisingly young age. For nobles, bigger population meant more labourers to work their lands, providing more surplus production to be extracted as the noble's income. They might well have had *access* to a contraceptive, but not enough *reason* to routinely use it. We can be sure about this because contraceptives did exist in medieval times, and did not cause a population drop. [Answer] Jdunlop has given a pretty good, well reasoned (but boring) answer - but there are some others that are more fun/interesting. **People like to f....ornicate** The first is very simple: People like to have Sex. A Lot of Sex. Even with modern contraceptives - it's a 1 in N chance of getting Pregnant (Condoms are 1 in 50 IIRC) - so have your society where people like to have a lot of Sex. It could be due to cultural reasons (Mass Orgy on Sunday! Bring your friends!), it could be Biological (The males are all well-endowed and the Women regularly climax), it could be less-positive (Lots of Rape/sexual assault). **Religion!** No one mentioned the Pope in the room? I told you to go forth be fruitful and multiply! Even today the Catholic church is opposed to Contraception, I believe there are similar prohibitions in the other Abrahamic faiths. Even if we put aside a prohibition against using the contraceptive for part or a significant part of the society - we can still go with the above - their religion encourages regular sex! **Natural differences in root strength** This is one of the big issues with 'natural medicine' - consider Cannabis - two different plants can have wildly different THC content (the active chemical) - meaning that for a given weight consumed/smoked you could be getting either a double or triple of the required dosage or not enough. Whereas Modern Medicine has the ingredients refined down to a precise amount. This natural variation can mean that it's not *as* effective as it otherwise would be. Then throw in natural variations of fertility, perhaps even throw in some other common foods that interfere with it (IIRC Grapefruit and the Pill don't get along well - Maybe some ladies can confirm) and you've got something that means it's not effective enough at causing a declining population. **Bloody Melee and Hand-to-hand combat** What does this have to do with Children? Well, why are the Baby Boomers called that? You had a lot of young men, who had gone off to War (WW2), seen their own mortality and had an innate evolutionary desire to extend their genetics - by spreading their seed far and wide. The result? a Big increase in population. This is as true today as it was then. Add in that Wars/Fighting means that there is less Men available (as they die in combat) so the average Man has higher sexual value than usual - - therefore they get to be horndogs and sleep with more women than perhaps they otherwise would. On the flipside - Women love a Man in uniform and love a victorious hero - all that Testosterone flowing around from surviving melee combat and all that estrogen flowing from seeing a Man risk his life for the sake of the city = lots of post-combat sex and that means a lot of babies. [Answer] ## They don't get educated The vast majority of medieval population was not educated. It was commonplace for nobles and even royalty to be illiterate; they had clerks to write and read for them. Medieval culture lived very close to the margins. No one was going to spend the time and money to educate people who could not make immediate practical use of it. Why would you teach a girl to read when you could put her in the fields shouting to scare birds from new-planted seeds? Or carding wool? Or spinning? Not to mention the fearfully high child mortality rate meant that many babies were needed to attain replacement birth rates. [Answer] ## Middle ages population was not determined by birth rates The middle ages where a period when the [Malthusian trap](https://ourworldindata.org/breaking-the-malthusian-trap) was in full swing. During the Middle ages, the primary source of wealth was food - having it, being able to produce it, etc - with much of the population devoted to it. A small percentage of the population didn't produce food - the crafters, merchants, townsfolk, and nobility mostly. Whenever the wealth of society increased, the population soon followed. It grew to the point of malnutrition, where there wasn't enough wealth for everyone to be food secure and healthy, and then fell with famine or disease or war. After a famine or disease caused the population to fall, wealth per person would increase, followed by a population increase and a collapse in living standards. While most of the population is working on producing food, the food capacity of the area is determined by the workable land moreso than the number of people working on it. Adding more hands increases yield, but only marginally - so you get more total food out of a parcel of land, but less food per person, as you add workers. When the population is low, there is lots of surplus food. As population grows, the countryside exports people to the cities (2nd sons who aren't inheriting the land and don't want to be 2nd class peasants in the country). The cities are a population sink, with more people starving/dieing than being born there, but still better off than being a vagrant in the country: you have a chance of being successful. In areas that split land instead of handing it to the eldest, instead you have the farm plots getting exponentially smaller, until they are no longer big enough to produce food for yourself let alone your lords tax demands. A rich farmer who had lots of land and could employ dozens of labourers would in 6 generations produce a bunch of poor heirs who couldn't feed their family, even if they only had 4 kids per generation. ## It is the food production silly So to maintain middle ages population, you need to maintain middle ages food production; if you want a middle ages feel, you have to prevent escaping the Malthusian trap. Birth control alone doesn't do it, because for individuals having more children is going to both be a status symbol and help with the work. You might not be able to support those children's children on your land, but for this generation the help is welcome! The non-eldest surviving kids have to find an alternative to being a land owner (or have peasant rights to farm some land) just as in the middle ages. And if you have enough land to support even a few helpers (which you need if you want to survive a famine), isn't it better to employ your kids than some other family? Maintain food production levels, and don't give people profitable alternatives to making food, to keep Middle ages style demographics around. ## How the real world got out We found non-human and non-animal sources of energy. When the only work you can do is from food, food determines how much work your economy can do. Wind, water and coal power provides sources of work that don't require growing food; so the wealth - the useful work done - of an area rises above the crops and animals it can grow. Unlike food energy, wind water and coal energy cannot be converted into food calories. So production boosts in them cannot be swallowed up with more mouths to feed, not without trading the produced products of that energy away for food. But it does replace difficult work that was done INSTEAD of making food - powered looms replacing human effort at weaving ends up saving a lot of "food calories" and produces something people sacrifice food calories for (cloth). Having more and more of the economy not devoted to food production, and sustainably so, results in the practice effect - we get better (at a society) as those tasks. Metallurgy, clothmaking, machinery, construction, engineering, entertainment, education -- all skills that we become better at as more of society is aimed at producing non-food goods. The countryside is still full of people producing food, but as noted if you drop the countryside population in half you get nearly as much food produced. What more, if you drop the countryside population in half, the countryside *exports more food* because it eats less. And non-human food production -- like using land to grow sheep for wool -- leverages this even further. The logic of this results in horrible crimes and "clearances" as peasants are forced off the land. The city population swells, but with the industries built on the back of non-food energy there are jobs for many of the impoverished peasants. Coal mining, working on mechanical looms, lumber to provide raw materials for ship building, servants of the increasingly wealthy merchant classes, etc. Insanely more people working in these non-food-calorie jobs, many of which require education, results in an accumulation of expertise and those jobs becoming more efficient. [Write's Law](https://en.wikipedia.org/wiki/Experience_curve_effects) kicks in, making the industries more efficient, which makes doing the industry more profitable, which makes having more people working in the industry economical, which feeds back into itself. As it happens, this increase in mechanical skills feeds back into food production, dropping the number of workers you need to produce food as tools to increase food production efficiency drop in price and increase in quality. ## How to trap your fantasy You could probably just cut coal. Without coal (or its equivalent) you are stuck with windmills and watermills as your source of non-food calories. Coals provided heat without using up land to grow wood initially. Coal mining to power steam engines led to better steam engines, both to pump water out of coal mines and to power trains and steamships to move goods around. Improved steam engine design led to more efficient, well, everything - and feedback between metallurgy, mining and energy production spiraled upwards. Remove coal and wealth remains tied to how many calories of work you can get out of the land, which is fixed. [Answer] I'm not sure that this question can be answered in a socially acceptable manner. There are few topics that will get people shouting their one true answer at you as loudly as with birth control. The factor that is most likely to affect birth rates is whether or not women are allowed to choose whether or not they will get pregnant. Birth control has little or no effect on birth rates in cultures where it is severely stigmatizing or illegal. If women aren't allowed education or full employment, they also lose this choice. In the Middle Ages, it was common for women to continue bearing children, even when the activity became life-threatening. However, the original question doesn't actually ask about pregnancy rates, birth rates, or even population growth. It asks about population size. Population growth is the difference between births and deaths, and decreased infant mortality can more than make up for a lower birth rate. Population size just means that people aren't dying as fast as they are born. This probably wouldn't be the case if the nobles are still throwing all of their excess men at each other in perpetual warfare, but that isn't a necessary quality for that time period. [Answer] How long of a time period is your story set in? This birth control method might be a relatively recent discovery. Your civilization might demographically collapse in the next several decades, just as some of our current civilizations will if they stay on their current courses. But this does not have immediate effects right now besides some people worrying about the distant future of their culture. So the population is high because it increased rapidly in the past, even if it is declining right now (or will soon begin to decline). [Answer] I believe there is something wrong in the assumption that access to birth control would lead to a decrease in population size. I would expect most persons in a medieval type of society considers having many childrens as something positive from several reasons: * Quality of life at old age. As there are no pension systems or similar, the children are expected to contribute to their parents old age. Having many childrens is the equivalent of todays saving account. * Religion: see as example how the catholic church as of today (in our world) thinks about birth control. * Most of the peasant population probably has not even heard of the birth control root - communication of news is very restricted in a largely non-literate society. This probably means that birth control is only used by a very small part, mostly wealthier, part of the population. * A larger work force is needed in agriculture work as newer labor saving inventions are not in place, or at least spread very slowly. * There could be other sociological factors as well. Maybe having children is not only done by land-owning married couples, it could be done in more "loose" relations as well. Perhaps all children are taken care of by a larger group than the main family, and hence any women of child bearing age tries to add children of their own. [Answer] **Farm families need children in order to thrive.** Families on farms have historically been larger than families in cities. From the age of seven onwards, children in a farm family do some of the work. Enough work so that they are a net plus to the wealth of the family. This is very different from the pattern in an urbanized setting, where children represent a net expense to the family until they are about twenty. So farm families are not motivated to remain small, even if they can get birth control. This is in addition to the other factors listed in other answers, such as high infant mortality rates. [Answer] Seems to me like you have a solution in need of a problem. Think about how your society will work. When all those women are forgoing bearing and raising children in their prime child-bearing years in favor of obtaining an education, where do the children come from? [Answer] **War in neighbouring countries** Although the other answers are reasonable, you could also consider this reason if it's better-suited to your setting. Historically people flee war, and something similar could apply here. If there's a war in neighbouring countries, their people could flee to your kingdom, and of course your population goes up. Examples, some historical, some modern: [Siege of Jerusalem in 1187:](https://en.wikipedia.org/wiki/Siege_of_Jerusalem_(1187)) > > Balian found the situation in Jerusalem dire. The city was filled with refugees fleeing Saladin's conquests, with more arriving daily ... > > > [Mongol invasion of Hungary:](https://en.wikipedia.org/wiki/Mongol_invasion_of_Europe#Invasion_of_Hungary) > > Following their decisive victory, the Mongols now systematically occupied the Great Hungarian Plains, the slopes of the northern Carpathian Mountains, and Transylvania. Where they found local resistance, they killed the population. Where the locale offered no resistance, they forced the men into servitude in the Mongol army. Still, tens of thousands avoided Mongol domination by taking refuge behind the walls of the few existing fortresses or by hiding in the forests or large marshes along the rivers ... > > > [During the German conquest of France, phase two:](https://en.wikipedia.org/wiki/Fall_Rot) > > Between six and ten million civilian refugees had fled the fighting and clogged the roads, in what became known as *L'Éxode* (The Exodus) and few arrangements had been made for their reception. The population of Chartres declined from 23,000 to 800 and Lille from 200,000 to 20,000, while cities in the south such as Pau and Bordeaux rapidly grew in size. > > > [The roads from Kviv to Lviv were heavily congested during the early phases of the Russian invasion of Ukraine, 2022:](https://www.sbs.com.au/news/article/air-raid-sirens-congested-roads-the-picture-from-safe-haven-lviv-as-russia-invades-ukraine/c1syknwul) > > "I'll just get in my car and head to Lviv" was a comment we heard often in Kyiv. > > > Hundreds of thousands of people had the same thought, judging by the congested roads out of the Ukrainian capital. > > > [Answer] **Frame Challenge: Why would medieval women bother?** I don't know why you're asking your question, but it might be that you believe that people 1,000 years ago would respond in the very same way as people would or do today to similar opportunities. Said another way, you might not be forgiving the past for being the past. I say 1,000 years as a bit of an average. The medieval period was from more-or-less 476 A.D. to 1450 A.D. with substantially different behaviors depending on which city in the world you pick to represent your society and which year. However, oversimplifying to the point that angels weep, we can basically say that it was a mysoginistic world lacking education or even the ability to benefit from education. Men were celebrated for soldiering or mastering a trade. Women were celebrated for having families and a well-managed household. Societies were frequently strongly influenced by religion — and human history easily proves that the easiest way for a church to grow is through births among its members, sugggesting religious pressure would make using the root taboo. Of course, we're completely ignoring the aristocracy as your question appears to be focusing on the majority of people. But that brings me to my point, why would a medieval woman bother with contraception (generally, not dealing with issues specifically like rape)? What's the benefit? Educated women — especially outside the nobility — were not prized for their education but were more frequently oppressed. Off-hand, I can't think of a significant benefit to using the contraception without changing the society to such an extent that it's no longer representative of the medieval era. I hope that I'm not putting the proverbial word in your mouth, but you actually can't assume that a demographic of a society in the significant past would obviously benefit as that same demographic does today if they just had access to the "freedom" enjoyed today. In every case, that freedom is enjoyed after all the intervening centuries of change (often bloody change). Corrollary: you can't have the perceived benefit without bringing all that change to the past and it's unreasonable to judge the past by today's standards. [Answer] Birth control was already a thing way before the middle ages. The ancient egyptians had it. [From Wikipedia:](https://en.wikipedia.org/wiki/History_of_birth_control) > > The Ebers Papyrus from 1550 BC and the Kahun Papyrus from 1850 BC have within them some of the earliest documented descriptions of birth control. > > > They still made a lot of babies anyway, most likely for the most cited reason in other answers so far: big families were economically advantageous for everybody. But let's say that in your world death rates are not so high that you need a lot of replenishment, people are educated, and for some fantasypunk reason there is no economic advantage to having many kids. You still have a couple big points of failure in your contraception process. First, **it's a root**. It only takes a blight to have everybody lose their contraception. One invasive species of grasshopper or fungus and you will have a long lasting, possibly century-long baby boom. Second, you need to be a botanist to have safe sex, in a world where illiteracy is the norm (and herbal knowledge possibly makes you known as a witch/warlock). Mistakes will be made, and considering the root isn't cheap (even if not expensive) there may also be a lot of ineffective, fraudulent material in the market. If your people are really smart they can pursue other contraceptive methods. But like TheDemonLord said, even modern contraception isn't 100% safe if you stick to cheap, non-drastic methods like condoms. Medieval methods would be even less efficient. ]
[Question] [ Lets assume that we have magic users that often like to hurt each other. Now the simplest option is to try to blast the other mage directly, but it is not without drawbacks. First the enemy will be often magically protected making our work harder. Second they will try to magick us back making the whole endeavor risky. The idea of hurling non-magical projectile at target using magic is known - it allows to attack from distance - and avoid or overcomes many forms of magical protection if the object is big or fast enough. Dropping object from great height is next logical step that occurred to the mages - spells to magick a mass high enough exists and are reasonably well known. Now my question is what could prevent escalation to the extreme - orbital bombardment? Assuming that spells to put a house sized object into orbit are available to reasonably powerful mage - and the cost of them does not increase proportionally to the destructive energy of object dropped. To clarify more there would be a two main ways to put the payload in orbit. First one is to levitate it up - if a mage can levitate a given object at all they can move it up as high as he wants until spell runs out - but it is slow - you can only get about 3-4 kilometers in hour. Second one is to teleport it instantly - again if you can teleport object of given size and mass at all you can teleport it anywhere - and as one can teleport payload to the other side of the planet without issues we have to assume that magic somehow takes care of rotation of the planet. Both spells are reasonably common and there are a lot of mages able to perform them. Now as the spells are common there is a very little chance that the target can detect them and know that this time they are used to make a surprise for them instead of simply moving goods and people around. [Answer] **Putting stuff in orbit cannot be done on the sly** Sure you can put a house (full of dog poop!) up in orbit, intending to magically drop it on me. But orbit is a long way up there, and the magical process of putting something there is super obvious to anyone with any magical sense. Not only does everyone know that the poop house is going up, but they see where you are too as you magically lift it. So now there is a house full of poop up there, and everyone with any magic knows you put it there and where you are. We don't know where you intend to drop it. But we know where you *don't* intend to drop it - back on top of yourself. And that is where we all think it should be dropped. Every wart witch, two bit warlock and lich at loose ends can afford a little magic umph to make sure that what goes up comes back down right on top of whomever sent it up. You are a doughty magician to be sure, with extra dought even, but you are no match for the combined spare magical change of the entire magical world. Poop house coming home! [Answer] Demigan already mentioned this in his(?) answer but accuracy would be a major issue. There are some reasons for this. **Air exists** Unless your mages have a solid understanding of aerodynamics and ballistics and can form the projectile very accurately despite the great distance it will tumble chaotically when going thru the air. This will totally tank accuracy even before taking things like wind to account. Generally if you are shooting another mage you can see, you should be roughly as likely to hit yourself as the target. **Rotating sphere** This is not an issue when forming things a reasonable distance above you so your mages might not know this but increasing the height also increases the radius. If the angular velocity is kept constant the linear velocity will vary based on your geographical location and the height. This will make the projectile move in relation to the target. It will also affect how the projectile tumbles thru the atmosphere. Alternately, if you try to keep linear velocity constant, which might be reasonable way for magic to work, trying to materialize things above certain height that varies based on latitude might simply fail because the location you try to materialize it in moves in relation to you. **Angular precision** When you are doing something at a distance, you are really targeting it based on angle and distance. How precisely you can control the angle would have some limit. The error in where the projectile drops caused by this would be proportional to the distance to the point of materialization. Note that error in the distance also hurts accuracy because of the sphere thing. **Time to hit** Longer the fall, longer the time your target has to move out of the way. This is a problem if your target is another magician who knows you have such an attack. Especially if they can sense your use of what should be a large amount of magic and recognize what you are doing. **Distance to hit** The longer the distance the projectile needs to travel before the hit more precise the initial targeting needs to be. This is a major issue if working well beyond any visual range that humans can conveniently manage. **Conclusion** Such orbital or high altitude bombardment would be only effective against large immobile targets. You would probably be able to hit a large city. Or an ocean to create a tsunami. Hitting things that are trying to kill you right now would not really be practical. Being able to hit things that are trying to kill you right now is pretty big deal as far as combat utility goes. So these spells would not be relevant to actual fighting. Maybe it could be used for demonstrations of force to convince cities to open their gates after they have no army or mages to fight back. Cities might have little fortifications and be assumed open cities by convention. [Answer] To quote HP Lovecraft (in an unconventionally literal sense) > > Do not call up that which you cannot put down > > > A wizard can put a boulder into orbit. So what? That doesn't suddenly make it *his* boulder. It's up there with a whole lot of potential energy, yes, but that potential energy can be harnessed by any other spellcaster. If you do all the work of lifting it into space, you still might have to fight with your enemy over steering it, or he might just teleport it back at you. At that point it's probably just a magical arm wrestle: which wizard can teleport the rock better/faster/more? I don't know exactly how your magic system works, but I would say the wizard who just spent a lot of effort lifting the rock into orbit would be at a disadvantage in such things. [Answer] # There's no magic in space, so you can't lift things into orbit like that. In the tabletop RPG Shadowrun, magic is created by living things. As a result, magic surrounds the Earth, but ends at the edge of Earth's atmosphere, and using magic in space is nigh-impossible. Sure, your wizard might be able to cast a Levitate spell to pick up a car and start floating it up into the air - but once they start reaching up towards orbit, the mana field thins out and the spell will fail, dropping it right back down. [Answer] 1: Accuracy. You need to know where your enemy is and where the object is. Throwing something from orbit on top of something moving on the planet is difficult as both are moving at different speeds. If you try to bring your projectile in geosyncronous orbit you both need to know the exact position of your enemy and where the geosynchronous position above him is, then drop it on top of them. That is some next-level calculation in your head, or a very very complicated spell! 2: object lifespan. Dropping something from orbit means it'll hit the atmosphere and heat up. Many objects will evaporate or break apart long before they reach your target. 3: collatoral damage. You dont want to be murdering entire cityblocks I hope? Especially if it takes a few tries the death toll could be catastrophic. 4: magical counters. If you can generate enough energy to lift something in orbit, you can generate enough energy to hold something inbetween you and the projectile and protect yourself. Or since your opponent has the potential to locate you, hang a projectile above you and then launch it down on you there should be the potential to locate random things going in orbit above you and launching something directly into it to protect yourself. In fact maybe they could take control of your projectile as you are trying to get it in orbit and rip a part off to drop on you while you are busy. [Answer] ## X Marks the Spot As others have suggested, aiming an object from orbit to the ground with any kind of accuracy is going to take a lot of computational power. Either via actual computers, or very complex mental calculations on the part of your wizard. And it gets even worse if we don't assume your target is stationary. Dropping a bowling ball on a house from orbit is going to be tough. Dropping a bowling ball on a moving vehicle from orbit sounds like something you would need a specialized super computer to manager. ## Air is Harder Than You Think The next issue with your plan is that air resistance ends up being way more important than you would expect. We know from the various objects that have been put into space that entering the atmosphere is *hard*, if you want your object to survive until the ground. Friction is going to cause whatever you send up to space to heat up and potentially fracture apart before it makes it to your target. A solid metal sphere like a cannonball would probably be alright, but try to drop something like a house and all you are going to end up with is a bunch of debris landing over a wide area. ## Horseshoes and Hand Grenades Lets assume that you have sufficient calculating power to aim at a target on the ground, and a tungsten rod that you can teleport into orbit. Good news, you have a KKV now! Bad news, using it would make you an international terrorist. The issue is that there is no way to have a small orbital bombardment. Even if you manage to hit your target, the blast radius is sure to be big enough to cause collateral damage. Even just having something hurtle through the atmosphere and not hit the ground can cause widespread damage. Actual impact is going to be so much worse than that. Imagine the Tunguksa Event, where a whole forest gets flattened, and then the same thing happening in a city. Yikes. The fact that creating a weapon of mass destruction is so easy for mages means that it is going to be heavily monitored and its use punished. The entire world is going to agree that this is a Thing That Isn't Cool and that anyone who actually use does it is a Really Bad Guy. You basically end up with a mutually assured destruction scenario where everyone has access to a weapon but agree not to use it. Otherwise your story is very quickly going to turn post-apocalyptic. [Answer] ## Terminal velocity I don't know why no one else has mentioned this, although it's been hinted at in comments: > > Being in orbit isn’t the same as dropping from a great height. If you’re in orbit you’re going sideways very very fast, so if your mages have the ability to ‘drop things from orbit’ then they already have the ability to accelerate arbitrarily sized objects up to hypersonic speeds. That in turn means a better question might be ‘Why aren’t my mages all magical super-snipers?’ > > > Let's look at three options: ### "Controllable" orbital velocity If your mages can accelerate things, either "directly" or through "teleportation compensation", then why bother using orbit in the first place? Just take shots at each other with hypervelocity projectiles. ### Orbital height, surface velocity If lifting something into "orbit" just means lifting it really high without also giving it orbital velocity, it's going to slow down as it falls through the atmosphere. In fact, it's probably going to slow to terminal velocity, at which point you might as well drop it from exactly high enough to hit terminal velocity prior to impact, which is far short of "orbit". ### Uncontrollable orbital velocity Okay, lets say you *are* dropping something from orbital speeds, but for whatever reason you can't just arbitrarily impart those sorts of velocities without the object actually *being* in orbit. Well... now you have to *drop* the object. The problem is, this is actually a lot harder than you might think. The whole point of orbit is that things *don't* just fall out, or if they do, they fall slowly, are hard to target, and tend to be destroyed by atmospheric friction on the way down. This just doesn't strike me as practical. If, on the other hand, you can teleport something into orbit, *with* orbital velocity, and then teleport it back *without* velocity compensation... well, now you're back to the first case of essentially being able to impart arbitrary velocity to an object. Even better, in this case you can teleport something from orbit to a spot right next to your target. [Answer] Kinetic energy is easy to harvest for mages. They feel it coming. It powers them. A projectile would shatter as a small portion of the energy it generated would be turned upon itself, while the rest would increase your opponent's energy reserve. Since it also costs energy to throw stuff at people, overall, it's not a wise or economical choice. At least against other mages. [Answer] Control of Magical energy decreases with distance. This means that a mage, if he or she is powerful enough, could get a house sized object into orbit even though the energy cost to do so is pretty staggering, but by sending it at a mage hundreds of miles away you are essentially giving your enemy a gift. The target mage can now take control of the object you put into space and send it right back at you using only a fraction of the energy it took you to push it into orbit in the first place. This problem is further exasperated by the fact that the enemy mage can convert the heat generated by the reentry of the object into the atmosphere and convert it into kinetic energy. So by sacrificing some of the altitude of the object, the enemy mage can take the energy the attacking mage spent in putting the object into orbit, and combine it with their own energy turning it into a standard kinetic thrown object in atmosphere but with a higher energy output than the enemy mage could use on his or her own, then throw it back at the attacking mage while he/she is still low on energy after getting the object into space in the first place. [Answer] The easiest one would probably be magical density. As you go higher the density of magic goes down, and thus it becomes harder and harder to maintain the power you need. In fact, link it to matter, so it's like neutrons except it provides magical pressure rather than gravitational. That way it's pretty much unchanged unless you've got a scientifically advanced society. This also lends itself to a magic as technology world, where instead of technological advances they make magical ones, with similar scientific underpinnings. [Answer] (Some numbers in the following are made up. Particular enchanters adjust the numbers to suit their purposes.) You see this ring? It's enchanted to provide a small lateral force to any object of density greater than 10 mg/cm^3 in the entire cone of space above me with cone apex at the center of the Earth and radius 30 m at the surface. The force's acceleration is radially outward from the cone axis at about 1 m/s^2 -- not even enough to levitate an object. You see this scarf? It is enchanted to detect objects out to a range of 10 miles approaching me at a speed greater than a running horse. It transports all their electrons 1 m backwards along their trajectory. They instantly disintegrate, with a great deal of lightning. You see this shoe? It is enchanted to detect objects carrying more that 1 J of energy and more than 1 kg m/s of momentum that pass within 10 cm of my body. It instantly turns the object insubstantial and leaves it that way. (Now I'm imagining a planet with billions of translucent immaterial boulders diving into and popping out of the ground constantly...) [Answer] **Insubstantiality** This sounds like the "Rod from God" concept [Kinetic Bombardment](https://en.wikipedia.org/wiki/Kinetic_bombardment) which is a fun read, but I would imagine the mages have an arsenal of magicks, including things like triggered spells, and the ability to become somehow insubstantial. So one could create such a trigger, "upon any mass coming within 2 inches of me, and moving faster than a common housefly, I shall become insubstantial". D&D calls this [Contingency](https://www.dndbeyond.com/spells/contingency). [Answer] It could be because it happened once, and now that mages have seen the horrifying results, such a thing is now considered "beyond the pale." Something like this happened in the book "Newton's Cannon" (I think that's the one). An alternate history book where very mathematical magic worked. A fairly young Ben Franklin proved some sort of mathematical proof and was horrified to learn that this had been used to destroy a European city. I believe that an asteroid was used to bombard the city. It took a while, but cities don't move. ]
[Question] [ *"At this very moment we face a threat insurmountable to Man. We are faced with two options. Stay on Earth and die, or leave Earth to space."* - UN Preservation Council, CE 2047 **Earth, year CE 2047** An asteroid is detected, traveling at about 5% Lightspeed, with a mass of about 1/2 the Moon. It also has a trail of asteroids with it, the average size being 3 times the mass of Apophis. The asteroids are on a direct course with Earth, and will impact in 4 months. Humanity prepares for the impact, evacuating to space and satellites around the planet and on Luna. **4 months later, January 2048, it happens** The asteroid impacts just off of the coast of Africa, about 30 miles into the ocean. The main asteroid impacts first, with the trail of the smaller ones impacting within 3 hours. My question is this: What would the effect be on the planet? How would the landscape change, and what are the chances of everything being destroyed? That being said, how long would it take for the surface to become habitable again? --Note-- * The main asteroid has a mass of 1/2 the moon's * The asteroid trail's average mass is 3 times the mass of Apophis * The asteroids are moving at 5% of lightspeed [Answer] # Earth is gone. The Moon is gone. Mars gets nuked. The entire Solar System becomes hotter than Mercury for a couple days. The Sun will appear to glow up to 12,000 times brighter. The Solar System will be forever scarred. As [jdunlop's answer](https://worldbuilding.stackexchange.com/a/163890/55824) says very succinctly, 'everything dies'. But let me tell you *precisely* how dead everything is. The asteroid delivers energy equal to half a solar mass of TNT to the Earth. One-20,000'th of this energy is used to reduce Earth to dust and hurl it to the far corners of the Universe. About one-100'th of this energy is used to push the Earth's remains in the direction of the asteroid's motion. The rest of this energy is used to blast out an omnidirectional spray of debris travelling at around 0.004 times the speed of light and to heat the Earth's remains to about a billion degrees. In other words, 99% of the asteroid's energy makes a plain and simple explosion. This explosion is powerful enough to destroy the Moon a hundred times over. This explosion will do the equivalent of nuking every square metre of the near side of Mars (and every other inner planet). With only 4 months to evacuate, you need to put a planet or the Sun between yourself and the Earth if you wish to survive, and to do that you'll need to fly *really* fast. If we assume that the ball of plasma which used to be the Earth radiates away energy following an exponential decay with a lifetime of about one day, similar to some novae, then the *entire* Solar System will receive many times more power per square metre than Mercury receives from the Sun for many days. The damage this could cause to icy asteroids and the surfaces of the outer planets is enormous. Even after the ball of plasma cools below ludicrous levels, the blast wave of debris would take a couple of months to sweep its way through the Solar System. This would present a second wave of destruction after the initial furnace-blast. To a distant observer, it will appear that the Sun suddenly grew up to 12,000 times brighter (a difference of 10.2 apparent magnitudes). The Sun would appear to return to normal after about 10 days under my very crude estimates. The Solar System will never be the same again. Any humans who managed to survive would find that the planets of the Solar System look very different to how they used to be. If you would like to see how I arrived at these conclusions, read on... --- The mass of the asteroid is about $3.7\times 10^{22}$ kg. Its velocity is about $1.5\times 10^7$ m/s. With a Lorentz factor of only 1.001, we can use the Newtonian formulae for kinetic energy $E=\frac{1}{2} m v^2$ and momentum $p=m v$ with reasonable accuracy. The asteroid has kinetic energy of $4.2\times 10^{36}$ J and momentum of $5.5\times 10^{29}$ kg m/s. For something interacting with the Earth, this energy is ludicrously large. Based on Wikipedia's [Orders of magnitude (energy)](https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)) table (which is one of my favourite tables ever), the gravitational binding energy of the Earth is a mere $2\times 10^{32}$ J. Exceeding this energy by a factor of 21,000, this asteroid easily turns the Earth into a rapidly expanding ball of plasma and super-heated dust being flung to the farthest reaches of the universe. But destroying just the Earth and removing it to the farthest corners of the universe takes only a tiny fraction of the asteroid's energy. *What happens to the rest of the energy?* ### Momentum Perhaps it goes into conservation of momentum (although I shall show that this is also only a tiny fraction). Earth has a mass of $6.0\times 10^{24}$ kg and orbital speed of $3.0\times 10^4$ m/s, so its momentum has magnitude $1.8\times 10^{29}$ kg m/s, which is of comparable order of magnitude to the asteroid's momentum, although the Earth's momentum could be pointing in any direction relative to the asteroid. Suppose for a moment that all the bits of the Earth were blasted away in the same direction as the asteroid's motion, and that the asteroid and the Earth were travelling in the same direction so that their momenta added together ($7.3\times 10^{29}$ kg m/s). The final velocity of the Earth in this scenario is $1.2\times 10^5$ m/s, with a kinetic energy of $4.3\times 10^{34}$ J (for reference, the kinetic energy of the Earth pre-impact is $2.7\times 10^{33}$ J). This is a mere 1% of the energy delivered by the asteroid. This means that the Earth can't explode in just a straight line, but instead must explode in all directions in order to get rid of more energy. As a crude estimate, if we assume that the energy of the asteroid all goes into the kinetic energy of this omnidirectional spray, then we would get the rubble going at a speed of $1.2\times 10^6$ m/s, or 0.004 c. However, as I discuss below, some of this energy will also go into super-heating the rubble. ### Heating Such an impact would almost definitely involve substantial heating of the Earth. Most of the Earth is magma (and iron, but iron has a lower heat capacity and similar boiling point). Your typical magma under atmospheric pressure has a specific heat capacity of about 1500 J/kg/K ([source](http://magma.geol.ucsb.edu/papers/EoV%20chapter%205%20Lesher&Spera.pdf): 'Thermodynamic and Transport Properties of Silicate Melts and Magma', Lesher and Spera) and while I do not expect this to be very accurate at mantle pressures it's probably the right order of magnitude. And we've already blown up the Earth into little bits, so it isn't under pressure any more. To heat up the entire planet by one degree assuming a specific heat capacity of 1500 J/kg/K would take $9\times 10^{27}$ J/K. The boiling point of silicon dioxide is 2950 degrees Celsius. Heating the Earth by 3000 degrees would take about $2.7\times 10^{31}$ J, which is a *tiny* fraction of the asteroid's energy. Having turned the Earth into a gas, we can approximate its heat capacity as being that of an [ideal monoatomic gas](https://en.wikipedia.org/wiki/Monatomic_gas), which is 12.5 J/K/mol (this is not necessarily an accurate approximation, but it's probably good enough for our purposes). Now we need the molar mass of the Earth. Based on the [composition of the Earth](https://en.wikipedia.org/wiki/Earth#Chemical_composition), the average molar mass of the Earth is approximately $56\times 0.32 + 16 \times 0.30 + 28 \times 0.15 + 24 \times 0.14 = 30.3$ g/mol, or 0.030 kg/mol. This gives a specific heat capacity of 417 J/K/kg. An Earth-mass of this gas would have a heat capacity of $2.5\times 10^{27}$ J/K. If we were to assume that almost all our asteroid's kinetic energy went into heating the Earth, it would reach a temperature of $1.7\times 10^9$ K. Over *one billion degrees*. Based on [another excellent table](https://en.wikipedia.org/wiki/Orders_of_magnitude_(temperature)), this is over a hundred times hotter than the core of the Sun and is the temperature range in which nuclear fusion reactions are measured. This temperature is ludicrously hot. At this point I have done maths which assumes all the energy goes into either heating or kinetic energy. Clearly this is a contradiction. The real answer would be somewhere between these two extremes. Precisely where I cannot say, although it's probably half-half to within an order of magnitude. ### Kaboom! Everyone dies The energies we are dealing with are ludicrous. Some of the energy will go into an omnidirectional spray of hyper-velocity rubble. Some of the energy will go into heating the remains into a ball of plasma which outshines the Sun. Regardless of the form of this energy, the result is quite clearly an explosion. A very big explosion. As I have calculated above, only about 1% of the energy of the asteroid goes into pushing the Earth. The remaining 99% of those $4.2\times 10^{36}$ Joules goes into making an explosion with the same energy as half a solar mass of TNT. Let us assume we have a spherically expanding blast wave. The energy per square metre (or fluence) is given by $E/(4\pi r^2)$, where $r$ is distance in metres from the epicenter (that is, energy divided by surface area of the blast wave, giving us the inverse square law). The surface of the Moon, which is $3.8\times 10^8$ m from the Earth, will receive a fluence from this explosion of $2.3\times 10^{18}$ J/m$^2$. That's the energy of eleven [Tsar Bombas](https://en.wikipedia.org/wiki/Tsar_Bomba) *every square metre*. The Moon has a radius of $1.7\times 10^6$ m, a circular cross-section of $9.1\times 10^{12}$ m$^2$, so will receive $2.1\times 10^{31}$ J from the explosion. The [gravitational binding energy](https://en.wikipedia.org/wiki/Gravitational_binding_energy) of the Moon is only $1.3\times 10^{29}$ J (approximately). The explosion is big enough to *destroy the Moon a hundred times over*. Clearly, anywhere in Earth orbit is not safe. Not even the Moon would shield you from the explosion. How far away does humanity need to be to be safe, then? Let's look at a Mars colony, which is the third most likely celestial body for humans to be on (after Earth and the Moon). Mars is between $5.46\times 10^{10}$ m and $4.01\times 10^{11}$ m from the Earth, with an average of $2.25\times 10^{11}$ m ([source](https://www.space.com/14729-spacekids-distance-earth-mars.html)). Mars will receive a fluence between $2.1\times 10^{12}$ and $1.1\times 10^{14}$ J/m$^2$ (unless it is hiding behind the Sun), depending where it is in its orbit. At the low end, this is equivalent to a layer of TNT 300 metres thick (based on a density of 1650 kg/m$^3$). At the high end, this is equivalent to three layers of [Fat Man](https://en.wikipedia.org/wiki/Fat_Man) nuclear bombs (closely packed, standing on their tails). (The polar regions would be better off than the equator, due to the oblique angle, but only slightly.) This won't destroy Mars, but it would definitely do nasty things to the surface of the planet and would probably destroy all but the most robust of Martian colonies. This is a problem for humanity. It takes around [7 months](https://www.mars-one.com/faq/mission-to-mars/how-long-does-it-take-to-travel-to-mars) to get to Mars with current technology, and in your scenario humanity only has 4 months. Since humanity has no hope of escaping the blast radius, their only hope in this scenario is to sit in space stations and space ships which are sheltering behind planets or the Sun at the time of the explosion. I hope you have some really fast ships. ### How long will it last? While total energy is one metric, another metric is power, or energy per unit time. Knowing the power will tell us how bright the explosion will appear. To know the power, we need to know how long the explosion lasts. However, calculating this directly would be beyond the scope of this site. So I will assume (as an extremely crude estimate) that our explosion will follow a similar initial energy decay profile as the nova [V1500 Cygni](http://www.aavso.org/v1500-cyg-nova-cygni-1975), since its light-curve has the data I need and it is also a cosmic explosion. The choice of this nova was very arbitrary and done by inexpert and brief searching, so I cannot guarantee that it is truly representative, but it's probably good for a rough guess. Over three days the brightness of V1500 Cygni decayed by 3 [apparent magnitudes](https://en.wikipedia.org/wiki/Apparent_magnitude), or a factor of 15.85. If we assume exponential decay $e^{-t/\tau}$, the lifetime $\tau$ of V1500 Cygni would be $9.4\times 10^4$ s, or 26 hours. From $\int\_0^\infty e^{-t/\tau} dt = \tau$, we can say that the peak power output of our explosion is $E/\tau = 4.5\times 10^{31}$ W. From [my second favourite table](https://en.wikipedia.org/wiki/Orders_of_magnitude_(power)), this is *12,000 times more luminous than the Sun*. It has a similar luminosity to [Beta Centuri](https://en.wikipedia.org/wiki/Beta_Centauri), one of the brightest 'stars' in the sky at a distance of 390 light-years away. Based on this very crude estimate, the explosion will deliver half of its total energy within the first $6.5\times 10^4$ s, or 18 hours. This first 1% of the explosion's power, the amount required to destroy the Moon, comes in the first 945 seconds, or 16 minutes. Of course, this model is fairly crude, as nova light-curves only capture the energy delivered by radiated light. In reality this explosion will have two components - the thermal radiation from the billion degree plasma, and the hyper-velocity wave of matter. The shock wave from the debris cloud would probably deliver the energy more abruptly, but long after the initial thermal shock. At 0.004 c, the blast wave would take 96 days to travel $10^{13}$ m to the edge of the Solar System, so even after the initial thermal blast has cooled off the material blast wave will still be a threat for a couple of months. It is beyond my capabilities to calculate what fraction of the energy goes into heating and what fraction goes into kinetic energy, but I would guess that they would be within an order of magnitude of 50%. In the following, for simplicity, I assume the energy is all thermal, giving an upper bound. You can scale down the brightness figures proportionally. Note also that the Earth's center of mass will only be moving a few times faster than its normal orbital velocity, so the Earth will mostly remain inside the Solar System for the duration of this explosion. ### But what if we go further away? Checking [this table](https://en.wikipedia.org/wiki/Orders_of_magnitude_(length)), the Solar System is only about $10^{13}$ m in radius. If you stood at the edge of the Solar System, you would receive a fluence of $3.3\times 10^9$ J/m$^2$, or about 786 kg TNT per square metre, or a layer of TNT half a metre thick. At a peak power of $4.5\times 10^{31}$ W, we get a peak flux at the edge of the Solar System of $3.5\times 10^4$ W/m$^2$, which is about 26 times brighter than the Sun at Earth's orbit. For reference, the solar flux at Mercury's closest approach of 0.3 AU is only 11 times brighter than the Sun at Earth's orbit. The entire Solar System will roast at temperatures hotter than Mercury for several days until the ball of plasma which used to be the Earth cools down. I hope you have a nice planet for shade. It is possible that these temperatures might destroy many comets and icy asteroids, wreak havoc on the icy moons, and possibly ablate away some of the atmospheres of the outer planets. And, of course, the inner planets receive a scouring similar to a rain of nuclear warheads. But what will this look like to an observer in another star system? The power output (luminosity) of the Sun is $3.846\times 10^{26}$ W. Our explosion peaks at $4.5\times 10^{31}$ W. This means an observer will see the Sun flare to be about 12,000 times brighter than normal, or 10.2 apparent magnitudes. At a decay of 1 apparent magnitude per day, the brightness would mostly return to normal after about 10 days, assuming my crude model for the energy radiation holds for that long. But don't let that fool you. The Solar System might appear to be back to normal from far away, but this explosion has scoured the face of the Solar System and left nothing unscathed. The planets will continue to orbit (besides Earth, of course), but the whole Solar System will bear the scars of this cataclysmic event for the rest of its life. [Answer] ### Everything Dies The combination of mass and velocity is inescapable. The follow-on asteroids don't matter. The initial impact will do the trick. Half the mass of the moon is approximately 36 sextillion kg. So the energy carried by the impactor is $$ \frac{1}{2} \times 3.6 \times 10^{22} kg \times (0.05c)^2 = 4.13 \times 10^{36} joules $$ While the [gravitational binding energy of earth](http://astro.osu.edu/~pogge/Ast162/Intro/gravity.html) is just $2\times 10^{32} joules$. So not even a molten surface - the entire earth would be blown away by the impact. It would never recover. You'd have an asteroid belt where once there was a planet. [Answer] # 5% of lightspeed is insanely fast for an asteroid. Earth is gone. It doesn't matter where that giant asteroid hits. Luna is gone. Some of the combined mass might form a new belt, but much will be "shotgunned" throughout the solar system. Stations close to Earth or the Moon will almost certainly be hit by fragments. [Answer] Let me provide an alternative for [jdunlop's amazing answer](https://worldbuilding.stackexchange.com/a/163890/21222). I will build up from that answer, assuming that Earth is completely disassembled. The change is that we won't have an asteroid belt. I will disregard relativity and other things because, well, once you've gone over four orders of magnitude the amount of energy necessary to disassemble the Earth, even big rounding mistakes won't change the final scenario. The incoming asteroid has a momentum of half a Moon times the speed of light times 0.05 meters per second. If we round the speed of light to 3 × 108m/s, we have around... $$(\frac{7.3}{2} \times 10^{22})kg \times (3 \times 10^8 \times 0.05)m/s = 5.475 \times 10^{29} kgm/s$$ Whereas the Earth has a momentum of about Earth mass × Earth orbital speed, so rounding the mass of Earth and her orbital speed a little upwards gives us... $$(6 \times 10^{24})kg \times (3 \times 10^4)m/s = 1.8 \times 10^{29}kgm/s$$ The asteroid has triple the momentum of the Earth. Supposing that momentum is conserved after the shock, the total momentum of the system would be anywhere between $\frac{2}{3}$ and $\frac{4}{3}$ the momentum of the incoming asteroid. For Earth itself, her orbital is speed averages 30km/s, while the Solar System escape speed at 1 AU is about 40km/s. This means that no matter the angle of impact, the plasma-that-was-once-Earth-and-asteroid will enter a escape trajectory, since its minimal speed will be around 60km/s. The following scenarios may happen: * It all falls into the sun. Little evidence remains that the Earth once existed. * It escapes into interstellar space. During the escape, observers may see a stream of plasma exiting the solar system at a speed that is compatible with a solar coronal mass ejection, albeit a billion times more massive than a regular one and possibly at an awkward angle. In both cases the plasma may impact on a planet, but it might be so spread out and so thin that it won't cause too much damage. May leave permanent evidence on the rocky ones though. ]
[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/152151/edit). Closed 4 years ago. [Improve this question](/posts/152151/edit) In my setting, soldiers carry with them kill-counters; devices that measure the lifesigns of everything in the vicinity and then count one kill if the lifesigns of a given humanoid suddenly ceases to exist without leaving the detection radius of the kill-counter (in order to award soldiers for prowess and also as a high-tech version of similar behaviour amongst samurai and Imperial Japanese soldiers). How could someone trick a kill-counter to rack up a high score without killing anyone? For reference, this counter works on 16-bit era computer technology, so it’s fairly rudimentary. Is there an obvious, or not so obvious, way to glitch it into registering a kill when none has happened? [Answer] Find yourself an inflatable sex doll and a sheep. Have the doll leaning on the sheep so that the not-so-clever sensor detects a live 60kg humanoid thing. Throw a rock at the sheep. He moves away. Now you have a sheep (computer won't care) and a non living humanoid thing. That's a kill! Repeat until the sheep can take no more. [Answer] In computer science, a computer that isn't under your physical control can not be considered secure. I would expect about a month before one of the more technical soldiers gets bored, cracks open their counter, figures out how it works, and wires in a button to increase the kill count by one, bypassing the detection circuit entirely. Then they would earn beer money by doing the same thing to other counters. You're not going to get a wireless connection to a central server using 8-bit technology on a battlefield, which is basically the only way to prevent this. The hardest part will likely be letting this pass casual inspection. Easiest way to do that is to bribe the person doing the inspection, though there are technical ways to do this. For example, the "button" could be a reed switch mounted on the inside of the case, activated by a magnet. That should be invisible unless the actual case is opened. To disguise any signs of opening, I suggest covering the counter with stickers, paint, or the like, or at least scraping it against a rock. Battlefield gear does not stay pristine, and screwdriver pry marks aren't going to stand out. [Answer] You say that your device works through eletroception, much like a shark nose. All you need are oscillators set to pulse at around 0.5 to 3 hertz. That's about what you'd expect from hearts on a battlefield (from 180bpm from the most frightened or raging combatants to ~40 from the dying). Keep switching them on and off, moving them around. When your superiors read your logs, it will seem like a true battle. Or, if the device is really stupid and you just want to rake in the kills... Go to any chicken farm and find the sexers. A sexer is a person who picks out chicks from a conveyor belt and find out if they are male or female. Then see where the males are thrown into and go there. [They are usually ground by machinery](https://youtu.be/BQ5qAfyUuWE). The smaller farms can grind hundreds of chicks per minute, the larger ones can do tens of thousands. Just leave your kill counter close to the machine and watch as it goes crazy. [Answer] Find something that blocks the detection of the kill counter. Say, if a massive wall of lead blocks it, construct such a wall, put a volunteer behind it, give them a beer or something else they enjoy, meanwhile run up and down on the other site of the wall, the kill counter will continuously switch between seeing and not seeing a life sign (other than yours) ... and profit. [Answer] ### Plan A: Reverse the polarity! A microphone is a device that receives vibrations from the air and converts them to electrical signals in its own circuits. But if you reverse the flow1 and push an electrical signal into the device (instead of passively receiving the output), then the microphone becomes a speaker, converting electricity back into vibrations. Your kill-counter device is a bit like that microphone: it receives electrical signals from the air and converts them to electrical signals in its own circuits, which register as "human" if they match a certain pattern. If you know the pattern, or the pattern is hard-wired into the device, a competent electrician could convert one of your kill-counters into a "lifesign broadcaster", pushing the signal back out into the air. For an individual solder, the plan might go something like this: * Pretend you lost your kill-counter. Request a new one. * Give the old kill-counter (and some cash) to a guy who knows a guy. When you get it back, it's been modified into a broadcaster. * Go out to the "battlefield". * Switch broadcaster on. Switch broadcaster off. Repeat. * Collect your medals. 1To be pedantic, this "flow" is not "polarity". But I couldn't pass up on a chance to use that title. ### Plan B: Integer underflow attack > > You know how in video games, if you get the super-duper high score, it eventually flips back to zero? > > > —Strong Bad, "4 branches", *Strong Bad Email* > > > This is the reverse of that. * Make sure your kill-counter is at 0. * Leave your kill-counter turned off until you find someone who's pretty close to dead. * Turn kill-counter on. * Do CPR to bring the almost-dead person back to life. Your kill-counter will register this as -1 kill. * Congratulations, you have killed 65,535 people. [Answer] On a simple system like this, you could pop open the cover and find the actual sensor, then make one of the power or data wires loose. Then simply moving around and losing data and/or power will cause the processing controller to misread the situation, deciding there's a kill when one of the "blips" goes "dark". If it's super simple, as you say, there probably won't be an algorithm to re-detect the life form. In fact, it might be missing purposely, since you wouldn't want your soldiers to be missing out on kills when they are repeatedly killing people coming out the same door, window, or cave entrance. It could be easily discovered, but it could also be written off by standard "wear and tear" of "someone so active". This all depends on how "hardened" the device is supposed to be. Modern military standards for equipment is pretty high, but these things still fail due to how much of a beating they can take. I'd have to assume that some rogue, splinter group isn't going to have the budget or the manufacturing capability to make a truly rugged device, so there's a good chance of these having a high failure rate. [Answer] The way you described the device, it is already incapable of fulfilling its main purpose, so subverting is kind of moot. You didn't mention how it detects *who* should get the kill. So if people travel in groups, everyone in the group will get a point whenever a single person makes a kill. You could just attend a lot of executions, and come early so you can have a front row seat, to rack up the points. You didn't account for causality, so people dying accidentally near you would increase your score. A sniper or poisoner would fail to be awarded their actual kills. In fact, friends of the sniper's victims would end up kill-stealing from the sniper. The laziest approach here is to just hang out in an emergency room. Especially being around people who get resuscitated a few times is great, you get multiple kills from each person. Being a journalist following people on suicide missions is also another "easy" one. You haven't explained in detail *how* the device senses lifesigns, but most likely there is at least one material that blocks it (if it relies on electric fields, those are blocked with Faraday cages). You just make a box out of that material and have your friend go in and out of it repeatedly, and each one would be a "kill". As described, the device also awards a kill every time someone leaves its detection radius. So a racecar driver will score a kill for every spectator at every lap. Flying a plane or helicopter at low altitude (eg. above a busy highway) will have similar effects, as would just standing at an airport where passenger planes take off. Or you could find a big cruises ship and just keep stepping in and out of the detection radius. Even walking through a dense city center should do it. My bad - you did say "without leaving its detection radius". Of course the obvious solution is to just hack the device and overwrite the memory. [Answer] I'm going to assume you can't just hide behind a wall to trick the system or it would go off every time you enemy took cover and that they system can magically tell a human from an animal. In my mind this system would measure the fading heart beat as a soldier dies, so just have a friend of the person who wants to cheat the system go Daniel Craig's James Bond and have them slow their heart beat until the kill counter goes off. rinse and repeat [Answer] As described, this device isn't smart enough to distinguish friend from foe from neutral, or combat deaths from just death by any other cause. So what you do is just hide out in the trauma room of a hospital, or even the triage area of your own army's medical camp. People are always dying in those places. Might as well rack up a few free "kills" on your counter. In fact, you might get extra freebies, any time someone flat-lines but they're brought back with ~~a defibrillator~~ whatever they use to bring people back when they flat-line *(I am not a doctor. TV lied to me.)*, heck, you might "kill" the same target over and over again if they're right on the brink. ]
[Question] [ In this world, women generally live naturally longer lives than men. The typical female lifespan would be 125- 150 years, and a male would be 30-35 years. Our society attributes this to an ancient curse that God placed on the first man for disobeying him in the garden of eden and eating a fruit from the tree of life. While the first man and woman both ate from the fruit and were equally guilty of this sin, they were punished differently. Women would experience pain and possibly death in childbirth, while men would see their biological lifespans drastically reduced. This curse would be passed down through their children and infect all future generations. I am a scientist who has spent his life researching this topic. Rather than accept the myth portrayed by our religious leaders that has been indoctrinated into us since childhood, I hypothesize that there are biological reasons for the differences in lifespans. Ignoring social and cultural reasons in human society, as well as access to medical care, what in our biology would cause this vast difference between the sexes? [Answer] ### Radiation and fat cell distribution in the body. You've got a lot of options to accomplish your goal. Indeed, as other answers have pointed out the gap you're hoping to explain *already* exists, though it isn't as wide as in your setting. In that spirit, I'll suggest a potential agent which also has some real-world basis: **radiation.** There is some evidence that some forms of radiation are more hazardous to men than to women. The explanation I've seen is that there are some sex-linked differences in how fat is stored in the body, and arrangements more common in women tend to physically shield vital organs. So radiation has the same effects in women as in men, but the tissues damaged by the radiation are less likely to be those comprising vital organs. Men, on the other hand, tend not to have such protection. You can fiddle with the details to suit your setting better (especially if those are the average life expectancies you want), but the vital elements are: persistent, low-acuity environmental hazard which is invisible to casual detection; lethal effects of that hazard only occurring after a long period of exposure causing damage to accrue until a "noticeable" threshold is reached; and an unrelated physical structure largely restricted to women (for other reasons which exist without the hazard) which happens to *also* have a protective effect. This kind of setup also suits the scenario well. Radiation sickness and various cancers can certainly *seem* supernatural or divine, even to trained physicians, until enough relevant research is undertaken and understood. And the nature of randomness and average effects among groups would make the different outcomes very difficult to understand before discovery of the specific mechanisms underlying those outcomes. If you'd like to look at a novel in which this idea is explored, and with similar relevance, I can recommend > > *Seveneves* by Neal Stephenson. I recommend it all on its own, but it also has some interesting descriptions on how radiation hazards exist and operate on human bodies, and also gives some decent scale and scope for how much of an "advantage" women as a group might have against this specific hazard > > > [Answer] **This exists in reality** I mean, not as much as the gap you're talking about, but in general men live shorter lives than women. [This](https://en.wikipedia.org/wiki/List_of_countries_by_life_expectancy) organizes it in a nice easy table to compare various cultures, first world vs. third world, etc. The gap seems to be on average about 4-5 years. So the question is, why? And the answer is: it's complicated. Well, it's not that complicated, you can just say 'because men are men', but that doesn't answer it, or you could say 'because men have a Y chromosome and higher testosterone levels', but that's only marginally better. You could also say: "Because men typically engage in more destructive behaviors, like smoking or becoming overweight, engaging in riskier and more physically demanding activities on a whole, and that the typical male biology develops such that the average man has a body which takes more of a toll because estrogen seems to develop the female body to protect it more", which is both a mouthful and a bit closer to the truth, but on the flip side is just a bunch of vague reasons which collectively all contribute but are not satisfying individually. Or, as I say, 'It's complicated'. Check [here](https://ourworldindata.org/why-do-women-live-longer-than-men), [here](https://time.com/5538099/why-do-women-live-longer-than-men/), and [here](https://www.who.int/gho/women_and_health/mortality/situation_trends_life_expectancy/en/) if you want to do some research on your own. [Answer] > > Ignoring social and cultural reasons in human society, > > > Well, don't do that. What kind of terrible scientist are you? At least do your study across difference cultural and economic groups. This is pretty basic stuff. > > I hypothesize that their are biological reasons for the differences in lifespans > > > There are a [whole bunch of androgen-related things that reduce longevity](https://jech.bmj.com/content/70/4/324), especially with regards to immune responses being reduced. It has been observed that [men with their knackers chopped off live longer](https://academic.oup.com/jcem/article/84/12/4324/2864451) (and don't go bald, as a sort of bonus). [This applies to other species, too](https://www.theatlantic.com/health/archive/2013/04/study-spayed-and-neutered-dogs-live-longer/275121/). Note that the magnitude of these effects is probably dwarfed by the contribution of the social and cultural factors you are so thoughtlessly disregarding. [Answer] The difference in average life spans for elephants is roughly as big as you describe. They are elephants, so it can't really be cultural, but it is behavioural and not biological. Female elephants live in herds, and if a female gets so old or sick that she can't stay alive without help, she will be supported by her herd essentially because her knowledge and wisdom are useful to the herd. Male elephants live on their own, so once they are too old to take care of themselves, they die. [Answer] For any question that asks why a living system would be a certain way, the answer always lies in evolution. Every biological trait you can observe has evolved. Even something as seemingly universally detrimental as aging happens the way it does because it represents an optimal evolutionary solution to the various forces at play. Exactly what those forces are and which of them plays the largest role is [still a matter of some debate](https://en.wikipedia.org/wiki/Evolution_of_ageing), but everyone agrees that aging is happening for some reason. So to answer your question we should ask another. "Why would it be evolutionarily advantageous for men to live shorter lives than women?" Evolutionary biology is a wonderfully complex subject and so there are plenty of possible reasons this sort of sexual dimorphism might evolve. Perhaps the most plausible though is an exacerbation of an [existing trend we observe in primates](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC22663/). There is a pattern that between the two sexes of a primate species the one that lives the longest is the one that spends the most time caring for offspring. In species where males take on the majority of child-rearing duties, males tend to outlive females, and in species where males don't participate in childcare females outlive them. From an evolutionary perspective, this makes sense because post-reproductive individuals can increase their fitness by caring for their offspring and potentially their offspring's offspring. So, if the evolutionary origins of your species involved social groupings in which males did not participate in childcare, regardless of the modern societal norms, that would explain their differing lifespans. [Answer] The females eat the males after mating. <https://www.youtube.com/watch?v=Os3OBJSlpUc&start=77> [Answer] All answers talk about testosterone levels and doing reckless actions. But in modern world this accounts for maybe 2-3%. The real culprit is selection shadow and grandmother effect. Selection shadow: after an individual has mated and produced sufficient offspring, rest of their lives does not matter much. We are talking about wild hominins. Thus a human dying at the age of 40 or 80 does not matter much. Most of them will not see those ages anyway because of other factors. Thus humans are not adept at surviving longer because they don't need to. Grandmother effect excludes human females from the above rule, which also is the reason humans are one of the very few animals that has menopause in the first place. In a social species like humans, grandmothers takes care of their young (even in wild) while the mothers continues their struggle for survival and more offspring. Because of menopause grandmothers cannot continue their own reproduction efforts dedicating themselves for this role. This ensures the children are taken care of, and the fit mother does not pause their survival and reproduction activities for so long for a human child to become a fit individual. Thus a tribe with healthy grandmothers are more likely to survive. This ensures women with stronger genes that allows them lead healthy life at their later ages, causing the disparity between males and females. From this point to your desired number is simply extending the the time passed since menopause is evolved. [Answer] **Nagging**. So think about it. Women far outnumber men in this society. Perhaps initially it's the result of a war. But from that point on, every young man born into this world knows his father probably only for a few of his early years, and is otherwise hounded and hen-pecked by his mother, grandmother, aunts, great-aunts, great-grandmothers, etc, etc, for his entire life. Wouldn't it make him want to check out early? [Answer] # [Semelparous](https://en.wikipedia.org/wiki/Semelparity_and_iteroparity) > > A species is considered semelparous if it is characterized by a single reproductive episode before death. > > > The best known examples are probably the anglerfish and preying mantis, though it includes many spiders and [at least one mammal](https://www.australiangeographic.com.au/blogs/creatura-blog/2019/09/the-little-red-kaluta-is-making-our-hearts-burst/). One thing to note is that all these creatures are at the small to very small (at least the males are) end of the size scale, so a human is a very large creature follow this particular model. If you want to try this approach then you don't want to bother investing so much energy into the males, make them much smaller add always having multiple births and you're all set. [Answer] Half of your question sounds like you're taking that religious nonsense seriously, are you sure you're a scientist? Anyway, you're talking about male/female life expectancy which is, first of all, a statistical value. Each generation has lots of factors that can influence it - from economic crises and wars to the state of roads in the country, availability of medical care and so on. Also, when talking genders, consider this - some countries still have official lists of professions prohibited to women, which would include stuff like heavy metallurgy or mining. Not because men are naturally stronger as someone would think, but because historically men are viewed as disposable material while women are the givers of life and have to be preserved by all means. This is reality in many cultures, but the way. But honestly, **all of it doesn't really matter when talking about lifespan of species.** You're "messing hot with round" - biology and statistics, the latter being influenced by aforementioned factors and a lot more, while biologically men could live the same amount of time as women - just look at those mediterranean villages in Italy or other such places with unusually high life expectancy unrelated to gender. [Answer] Exaggarate stuff that exists in real life. * Super-testosterone. Male balding is really annoying, and comes from our hormones destroying the hair (apparantly). What if males have some extra-awesome-but-destructive hormon? It could attack the aging part of the cells directly, aging men faster than women. Perhaps it bestows men the ability to heal faster (useful for fighting). "Burning the candle in both ends". Imagine a black market for "male healing shots", for women.. * XY vs XX. Men have conditions that women don't. Research them, and crank them up to 11. Colorblindness - make some interesting visual problems. Make cancer a male-specific problem, and discover it. Diabetes-like conditions. Alzheimers. Make everyone a bit suicidal, and men more successful at it. Pick and choose ;) The societal consequences are interesting. Will you care as much about health and safety, when your time is so much more precious? Will society care (even less) about men in war (they'll die soon anyway). Perhaps that snowball takes off with things like "men don't need safety equipment, tsktsk, just put them to work." [Answer] "I hypothesize that there are biological reasons for the differences in lifespans." There are, and testosterone seems to be [the main culprit](https://time.com/5538099/why-do-women-live-longer-than-men/). Men live fast and die young because their primary sex hormone makes them strong in the short run, but then weakens them in the long run, contributing to cardiovascular problems (particularly hypertension and atherosclerosis), a weakened immune system, not to mention hair loss. Men have other sex hormones, of course, which probably compound the problem. According to one [story,](https://www.bbc.com/future/article/20151001-why-women-live-longer-than-men) eunuchs often live 20 years longer than men with testicles. (That last link gives a great explanation) Estrogen, on the other hand, is an antioxidant that actually protects women's health in the long-run. I'm wondering...If this is a sci-fi or fantasy story that you're writing, why not exaggerate the difference in lifespans? The numbers you give are pretty close to reality, though I think men average closer to 70-75 years instead of 55-60. I think it would be really interesting to read about a society in which women live to, say, 125, while the men all die at, I don't know, 30? Just a suggestion. [Answer] As others answered, there must be long term evolutionary pressure to extend the lifespan of females. There may be no such pressure for males, or much less, or even opposite pressure. Others have proposed what such pressures might be and I won’t elaborate here. Rather I’ll propose how the resulting longevity genes benefit only females and never their sons. So, in this world, genes for 150 year female lifespan must result in the increase of those same genes in the subsequent generations. However, these genes for longevity must either not be passed to male descendants or are substantially counteracted by some genetic or environmental factor. Perhaps the easiest way to explain a genetic cause for this significant sex based difference is to use a sex determination system other than the familiar human XY system. Humans have two sex chromosome (XX in females, XY in males), but this is not the only possible system. Some creatures determine sex through the presence or absence of one or more chromosomes. For example, if the X chromosome is present, the embryo will be female, but if the X is missing the embryo will develop male. Now, imagine that all the genes needed for the development of long life are also present on the X sex chromosome. In this case, every female of this species would have the genes for long life and would pass them to her daughters but would never pass these genes to her sons. Using this alternate sex determination system provides the scientific basis for significant sex based physiological differences in a species far beyond what we might consider reasonable in our own species. [Answer] Make laws like in Russia which has the greatest life expectancy difference along with the cultural specifics. Make the police protect preferentially women, the healthcare treat preferentially women, make higher punishments for crimes committed against women and higher to male perpetrators than female. Make men lose everything including real estate on divorce. And obliged to supply the former wife. Make only males serve in the military under harsh conditions. Make females retire earlier and with higher pension. Make females receive higher grades in the universities "because she is going to marry anyway". Make "true man" culture where the men are required to go fight over any request by the woman and are shamed for seeking medics help. Make the emergency services to save females first. Make males to be expected to fully supply and pay for women they date. In short, everything Russia-like ]
[Question] [ Imagine a race whom have mastered the knowledge of black holes, at least a bit. They've found a way survive, with their planet intact, inside the gravitation of the black hole without getting destroyed by it. (I know it is not possible for humans but in my fictional universe there are species which understand the universe a lot better then we do.) Is there a way for the enemy to destroy the planets inside the black hole? I ask because all missiles or some cannon like the death star would be destroyed by the black hole and would the black hole also grow? Let me explain the following picture: 3 planets are in the gravity pull of the black-hole but around each planet there is a safe-zone created by a much more advanced race, they even have something like wormholes in the safe-zone so they can leave the black-hole's pull. There is no way to enter the wormhole for other species. If a planet gets sucked in by the black-hole, would the dismembered planet collide with the planets? I imagine the parts of the dismembered planet would rotate in a way people do in a funnel slide. I hope you grasp what I am trying to say. Edit: JDługosz helped me understanding the horizon, please read his answer and make new suggestions. 1. How can they find the localization of these planets? 2. Which weapon would be enough to destroy them and what is the best way to destroy all three planets at once (So they can't prepare a defence)? [![enter image description here](https://i.stack.imgur.com/Yb54P.png)](https://i.stack.imgur.com/Yb54P.png) Would something like this hit the planets? But— I mean something with physical form, planets or a sun, but in the form of the example. [Example](https://upload.wikimedia.org/wikipedia/commons/0/03/Black_hole_lensing_web.gif) [Answer] You need to understand better how the *event horizon* works. It is a point of no return. Your implicit idea of it being a shell that destroys anything that passes is simply wrong. From [physicist Matt Strassler’s blog](https://profmattstrassler.com/articles-and-posts/relativity-space-astronomy-and-cosmology/black-holes/black-hole-information-paradox-an-introduction/): > > A horizon is not an object, but a place beyond which escape is impossible. A famous analogy is to a boat approaching a waterfall, in an increasingly fast current. Once the boat passes a curve of no-return (see Figure 3), its engine will be unable to fight the current, and it will inevitably go over the waterfall. But the captain of the boat will not notice anything when crossing this curve; it is just an ordinary part of the river, whose importance will only become clear when the captain seeks to escape disaster. Similarly, in general relativity you will notice nothing when crossing the horizon; it’s only when you try to escape the black hole that you will discover that — oops! — you went too close > > > ![picture](https://profmattstrassler.files.wordpress.com/2014/02/bhip_waterfall.png) > > > A missile can enter the event horizon from the outside and hit the planet inside. They just need some way to aim when they can’t see in. You can find examples of general relativity scenarios along the line of Alice falls into a black hole, and some time later Bob jumps in after her and can still rendezvous. Similarly, missiles entering the black hole can target the planets inside. [Answer] You should watch [this video](https://www.youtube.com/watch?v=vNaEBbFbvcY) about black holes. Your premise is so nonsensical for General Relativity that you might as well be asking "why is the moon made of cheese?" Um... its not. Planets cannot orbit inside the event horizon, the only direction inside the EH is towards the singularity at the center. Everything inside will not retain a form recognizable to us. As @AnoE pointed out below, this applies after you are close enough to the singularity for tidal forces to tear you into a thin stream of particles, known as [spagetiffication](https://en.wikipedia.org/wiki/Spaghettification). However, just because an object can enter an event horizon and not be shredded immediately doesn't mean stable orbits are remotely possible. Thus, the answers to your questions are actually trivial: > > 1. How to find the localization of these planets. > > > The mass of these planets, along with all the rest of the mass of the black hole, is located at the infinitely small singularity at the center. > > 2. Which weapon would be enough to destroy them and what is the best way to destroy all three planets at once. (So they cant prepare) > > > Nothing needs to be done, they are already destroyed. You can't make this science-based, as your tag wants\*\*. The only way to make your premise make sense is to move to an entirely different universe with different laws of physics, because Einstein, Hawking, and others have proven this impossible. \*\*Note: the question was tagged as `science-based` when I first answered this. That has since been removed. I'm not updating my answer since people seem to find it helpful, however the changed context makes it less relevant to the question. [Answer] The simplest method would be a sabot attack. If you hi-jack one of the enemies ships and know how it gets back to the home planet, it should be possible to plant a bomb/virus on there that knocks out the safe zone generators. Once that's gone, the planet gets sucked into the black hole. Destroy one planet and you could well have a political/emotional victory. Faced with a third of their population (or the loss of their primary planet), they will need to negotiate an outcome. Losing a third of your resources (or centre of government) is pretty severe. If they don't face up to defeat, the same thing might happen, or all outgoing ships might well get destroyed. [Answer] Science has no answers for you. We have no empirical way to test hypotheses about what happens inside an event horizon, so the best we can do is *literally* an educated guess. Steven Hawking recently made one of those guesses about what happens inside the first few nanometers, after years of work, and the scientific community is still debating the validity of his claims. Your options are: * **Spin the planet** - A spinning black hole eventually loses energy to Hawking Radiation and gets smaller. Eventually such a black hole can dissipate. So, if you're patient enough to wait the quadrillions of years for it to dissipate, you can do something to the planets... if they're still there. * **Subterfuge** - Convince one of the members of that species to enter the wormholes and break down whatever magic is making this whole thing work. * **Magic** - This is one of those infamous "I invented a rock so heavy even God cannot lift it, now help me move it" sort of problems. You invented a technology which is so advanced that it literally operates beyond the known laws of physics. Use that same technology to attack the planets. When you invent rocks so heavy that even God cannot lift them, it is *entirely* plausible that said rock also cannot be lifted by science either. That's an inherent risk in such handwaving. I highly recommend reading the blog post on [Sanderson's First Law of Magic](http://brandonsanderson.com/sandersons-first-law/). What you describe qualifies as magic by Arthur C. Clarke's definition of magic, so you should plan around following Sanderson's First Law: > > Sanderson’s First Law of Magics: An author’s ability to solve conflict with magic is DIRECTLY PROPORTIONAL to how well the reader understands said magic. > > > Sanderson's law doesn't limit the options you have for solving this issue, but it does point out that you're going to have to make sure the reader is *very* comfortable with it before resolving major plot points using it. [Answer] **Use Their Own Weapon** Your best bet is to learn how they maintain a planet inside a blackhole. Assuming equal technology/science level, your scientists and engineers most likely could reverse the method. **Espionage** If your race is far inferior in technology and you can't reverse engineer the method, then you try to capture a ship, plant some kind of a GPS/analytic device and send it back to analyze the road. **Antimatter Missiles** In theory antimatter doesn't destroy a blackhole completely but as far as we assume, big powerful antimatter missiles will create huge explosions inside the blackhole but even then the energy won't escape and the blackhole will grow larger. [Answer] Cover the surrounding of the black hole with antimatter dust. The dust particles will fall into the black hole, and since they are everywhere, statistically *some* of them will hit the planets, and a matter-antimatter explosion even of a few grams of antimatter will release as much energy as an atomic bomb. [Answer] You are facing the problem that the tidal forces of the black hole will destroy any missile you can throw at them. Thus the only solution I see is to throw a missile that is immune to tides--another black hole. You still have the basically-impossible targeting problem of knowing where the enemy planets are hiding. However, you don't need a direct hit--all you need to do is overload the gravity generators that are protecting the enemy planets and their own black hole will finish the job. [Answer] Find a way to divert a neutron star into the black hole. They are super dense already, and would add dramatically to the mass of the black hole, and would change the size of the black hole and the radius of the event horizon. Then the aliens planet would be actually inside, or further inside, and perhaps their technology might not be able to adapt to or overcome that difference. [Answer] **Only a god can kill a god** What you could use is the classical **traitor** scenario. If your alien race is so advanced, i higlhy doubt there is any way for an inferior race to take them in a frontal way. So what humanity (or whatever inferior specie) need to destroy their planets is an inside man. Some kind of pariah from this advanced race who just happens to hate that much is own kind that he will help you gladly to wipe them out (did anybody said Avatar ?). As far as **how** he would help humanity to destroy his own kind, i guess he could use his great knowledge in blackholes to create a small one within the safe zone of a planet. I'm pretty they wouldn't have planned that [Answer] No one knows what exactly happens after you pass event horizon (which is just outside the black hole, which is point of no return. Since it's point of no return we don't know happens inside). > > Most likely enemy missiles will transform into information or some kind of dense mass(energy) before hit your planet which is inside event horizon. So enemy can't aim or destroy your planet. Not only that they'll never know if they hit the target or not after random attack. > Of course in case enemy master same technology as yours then can send probes into inside event horizon then they can aim and send missile that withstand even horizon. > > > [Answer] If you want to mix magic and popular physics, introduce the idea of gravitational wave 'earthquakes'. The people on those planets may be magically protected from a constant gravitational field, but a gravitational wave disturbs that constant field and squashes the planets into egg shapes, causing earthquakes, eruptions, etc. [Answer] **Chuck another Black Hole at it.** First of all, technology that can protect an entire planet from the harsh environment of a black hole (not to mention the extreme gravity!) must be pretty sweet. All infalling matter would have already been accelerated to relativistic speeds by the time it got to the planet. Basically, a missile (even an antimatter one) would be nothing compared to what the planets already encounter every day from just in-falling dust and extreme blue-shifted radiation. Now, if its possible at all to destroy these planets, colliding the blackhole with another blackhole just might be able to crush these planets. If we assume that the black hole in your diagram can fit 10 earths side by side inside it, and we use a [formula from Wikipedia](https://en.wikipedia.org/wiki/Black_hole), we can compute that your black hole has a mass approximately equal to 27,000 solar masses. This is about 1/4 the size of the smallest super-massive blackholes. In the black hole collision detected last year, about 4.6% of the mass of the two black holes colliding was released. If we chuck another black hole similar to the size of the black hole in your diagram at it, and we assume a mass loss of 1%, 540 solar masses of gravitational energy will be released in the collision. For the sake of your aliens, I hope that their gravity shields can protect them from that much energy. [Answer] My answer is specifically based on Destroying the planet thus in any manner we will not be able to visit or colonize the planet afterwards. If we can somehow simulate an experiment which increases the **hawking radiation** on event horizon the black hole will eventually lose mass and destruct. Exponential growth of particle and antiparticle pair creation will speed up the process. [Hawking radiation (Wikipedia)](https://en.wikipedia.org/wiki/Hawking_radiation) ]
[Question] [ In an effort to make it possible for fantastically large organisms to exist I've altered the square cube law of my universe so that instead of something getting 8 times the mass when doubling size it instead only doubles its mass, three times the size three times the mass instead of 12, etc. So far this is the only alteration of physics I've made, with all others remaining the same. While this might work to make creatures larger, I found myself wondering, what other effects or consequences for lifeforms would this altered square cube law have? [Answer] **Wrong Question. There is a Different Solution.** The real question you have here is "*how do I make extra large creatures feasible*," and you're looking for a solution for this by tweaking the square cube law. That's a problem: you can't. It's a geometric rule that relates area to volume. You can't change that without doing some really weird stuff physics-wise, like warping space. But if your problem is how to make large creatures more feasible, there is an answer. Take the strength to weight ratios of an ant, a cat and an elephant. The ant is super light, but can carry many times its own weight. The cat is heavier, but due to its muscle strength vs its body weight, can still jump many times its body length. The elephant however, can't even jump. Not that it's not strong, but the strength scales with the cross sectional *area* of the muscles. And the weight increases by the total *volume* of the creature. So the strength doesn't decrease as much as mass decreases going smaller, but it also doesn't increase as much as mass increases going larger. This is a simple geometric and biological fact of life. What you want to do here, is tweak the scale. If you were to make normal humans have strength to weight ratios of smaller animals, it would mean that the upper weight(or in this case, volume) for animals is much higher overall. Normally if you were to get too large, the bones or the muscles would no longer be able to support the weight. So finally, to get to the point, the thing you really need is to change is: the *mass to volume ratio*. **Change the Mass to Volume Ratio** Simply put, you can have larger more complex creatures behaving as if they were at the scale of much smaller creatures if the matter itself that they are made of is lighter, but functions in the same way otherwise: the same strength of muscles, but the weight of the body is lighter. This would mean your larger creatures could get truly BIG. Their muscles and bones would be able to handle much more mass. Your humans would be able to do things that would seem superhuman from our perspective. They would be able to lift much larger objects, and jump further, fall farther, with no ill effect. In fact, if you had melee weapons in this universe, they might look oversized by our standards, in order to make up for the lost mass. And thus you reach the realm of *Final Fantasy physics*. The effect this would have on planets and the landscapes, I'm not entirely sure, but perhaps mountains wouldn't be compressed as much and slopes could be more extreme before crumbling. Perhaps the atmosphere would reach higher. The planets would have to be larger than Earth to have the same force of gravity. It would make life easier for flying creatures as well. So there you go, I hope this helps you with your problem. If anybody has major issues as to the feasibility of this solution, leave a comment! [Answer] Square-cube law is a consequence of us living in a space with 3 spatial dimension, is not a whim made up by bored biologists. > > when doubling size it instead only doubles its mass > > > You have created a 1 dimensional universe, [where](https://en.wikipedia.org/wiki/Spacetime#Privileged_character_of_3+1_spacetime) I doubt life can exist based on scientific criteria (you can't have an in and an out to start with). [![enter image description here](https://i.stack.imgur.com/XgndV.png)](https://i.stack.imgur.com/XgndV.png) > > if N < 3, gravitation of any kind becomes problematic, and the universe is probably too simple to contain observers. For example, when N < 3, nerves cannot cross without intersecting. > > > In general it looks like such a universe in unpredictable. On purely fantasy criteria instead, Abbot skimmed through such a world in his masterpiece [Flatland](https://en.wikipedia.org/wiki/Flatland), when the protagonist visits Lineland. [Answer] If by mass you mean gravitational (passive) mass, then what you suggest is kind of doable, if we postulate that in your universe, gravity is shielded by matter. That is, gravity is not something that fundamentally affects your geodesics, but it is a mundane interaction force mediated by relatively high mass particles, or something. This means the "mass" (i.e. sensitivity to gravitation) grows with the square of linear length, which is still much better than in our universe. And let's assume that gravity from inside of huge astronomical bodies slowly "leaks out" until an equilibrium is reached, so that planets and stars work more or less as usual. The differences are numerous - a sheet of matter might be enough to shield you from Earth gravity, flight (including interplanetary flight) will be much easier. Evolution will probably not even get to the wings, flying creatures will extend sheets of thick matter to shield them from gravity, and they will be tall and thin, to expose the smallest possible cross section to the planet. (conical) Skyscrapes will be almost trivial, because they will be shielded from the most of the gravity. Less incentive to develop wheels, when a sleigh is enough. And many, many more examples. [Answer] You have a severe problem. As @RichardTingle asked: > > How does this work self consistently? If eight 1 metre square cubes > each 1kg in mass are stacked into a 2m by 2m by 2m cube does their > combined mass suddenly drop to 2kg. Do cubed actually have to touch to > get this "disappearing" mass? > > > To really show the problem, consider the reverse: take a cube that's 1 meter per side and weighs a kilo in total. Now divide that cube into 8 equal smaller cubes each 0.5 meters per side. In a normal universe, each smaller cube would mass 0.125 kg (1/8th of a kilo). In yours, however, they can't. They'd mass 0.5 kilograms each for a total mass of *4* kilograms. (Don't see how that works? If doubling the dimensions doubles the mass, a cube 0.5 meters per side going to a cube 1 meter per side that masses 1 kilo has to mass 0.5 kg to start.) Now do it again. Divide each of those 0.5 meter sided cubes into 8. Each 0.25 meter cube has to mass 0.25 kilograms. But now there's 64 of them, each means the total mass has increased to 16 kilograms. Now do it again. Divide each 0.25 meter cube into eight 0.125 meter cubes, each of which has to mass 0.125 kilograms. But now, there's 512 of them, and the total mass of all those cubes is 64 kilograms. Starting to see a pattern? Cut them in half again, the total mass will be 256 kilograms. Cut them in half again, 1,024 kilograms. Cut in half again, 4,096 kilograms. In other words, if you half the size of something, the relative mass goes up by four times. In such a world, I trust you wouldn't buy your children Lego: the individual bricks required to build a structure might require a box capable of holding several tonnes. And that pretty succinctly, I think, illustrates the problem. [Answer] > > While this might work to make creatures larger (...) > > > It doesn't, really. The real Square Cube Law maintains density as you scale things up. Your altered Square Cube law means that everytime you double length or height, stuff becomes 12.5% as dense as it was before. Now using the standard Colombian measure of Shakiras... One Shakira height is about 157 cm and one Shakira weight is 53 Kg. If you got Shakira ballooned up to 16x her size, she would be 25.12 m tall (about the distance between baseball bases), but she would weight only 848 kg. She would go from 1g/cm3 to about 0.000025 g/cm3. That is lighter than air and she would float like a Zeppelin. Likewise, all your Kaiju would be doomed to forever fly above the stratosphere. They would also be fragile as cotton candy. [Answer] **Frame challenge: Reverse Your Approach** Instead of messing with universal constants or geometric principles, change your standard for the people. If your "average person" is 3.5 feet tall (completely plausible) , then a 7 foot tall person (also completely plausible) is an absurdly huge giant. If you really feel the need to have a physics-plausible universe, but want giant monsters and massive beasts, just make the people smaller. [Answer] **You're developing a fantasy world where physics don't work like they do on Earth. Wonderful! That's literally what the Help Center says our Stack is for!** The square-cube law is nothing more than an expression of the relationship between the volume of an object and its surface area — and what I suspect is happening is people are getting stuck on your phrase "I've altered the square cube law" and what you say after that. > > ...something getting 8 times the mass when doubling size it instead only doubles its mass, three times the size three times the mass instead of 12, etc. > > > In other words, what you're really changing is the relationship between gravity (or something else) and the square-cubed law (SCL). ***Cool!*** Let's fool around with a few relationships: **Density vs. SCL:** You could say that the density of any material in your universe *decreases* without the loss of any structural strength or other appropriate characteristic. So, as a creature gets bigger in your world, the heart of that creature does not need to become impossibly large or complex because the amount of blood being pumped and the distance the blood must travel benefit from the blood being a lower density *without losing any of its value as blood.* Curiously, this means that as creatures get larger, they get stronger! A large creature (having lower density muscles that haven't lost any of their strength per-cubic-meter) could jump higher than a small creature (normalized by mass) because there's more cubic-meters worth of muscles without the accompanying increase in weight. **Gravity vs. SCL:** You could say that the consequence (force) of gravity in your universe *decreases* as mass *increases.* This doesn't mean things float away, only that the planet is more attracted to its denizens than its denizens are attracted to the planet! That could mean that all solar systems orbit around a barycenter because the sun isn't necessarily the largest gravity source in the solar system. (There could be a lot of fun with that...). I'd vote to call this one the "Weebles universe," because everything wobbles without falling down. **Energy vs. SCL:** You could say the biological *need* for energy decreases with increasing mass. This one's a bit harder to swallow, but fun nonetheless. The problem is rationalizing how anything would be *small.* After all, Nature would favor larger creatures because they need less energy (per-cubic-meter) to do the voodoo they do than smaller creatures. **Conclusion** What's the consequence of changing the relationship of the square-cubed law with something in your universe? In your case, and generally speaking, it will mean that Nature favors larger things over smaller things. And that's important, because here in the Real World, nature favors smaller things over larger things. It's difficult to imagine a world where elephants outnumber mosquitoes, because modifying the relationship of the square-cubed law with anything means that you're changing the balance of small-vs-large, but that could be a lot of fun! *How would a world pollinate flowers when the average bee is larger than the bloom?* Answer: the flowers would be bigger, too. What you won't have is people being *just like Earth people* experiencing mega-fauna that we wouldn't see on Earth because your people are also subject to the effects of those modified SCL relationships. But let's ignore that, because it isn't any fun. What you really care about are the *secondary consequences.* Like the ability to jump higher when you're bigger or the ability to live longer because there's less energy dependence or how utterly cool the night time sky would look because everything's wobbling! Those are the interesting consequences of goofing around with the relationship between the square-cubed law and other things. Now, if you want more details about what advantages and disadvantages could come from messing around with such a relationship, that would require another question that asks about just one relationship. [Answer] What if you let your story take place on a much smaller planet? Creatures would be able to get much bigger. The mass would be the same but they wouldn’t collapse under their weight. You could still have smaller creatures too, like we have ants. Alternatively, rather than changing the square cube law, change how strong a force gravity is. [Answer] Increase the breaking strength of muscle fibers and increase the gas-in-liquid diffusion rates. The limits on muscle strength are these two. If gasses diffused faster and if muscle fibers broke at a higher limit then creatures could be larger. It would be tempting to increase muscle strength by strengthening the weak bonds; but that breaks everything. Rather, make slightly better biochemistry available. The actual chemical limits exceed what biochemistry can currently make, and there's no hard reason why biology can't use better materials. I can't come up with a reason why muscle fibers can't be half as string as spider silk, nor can I come up with a really good reason why there's no tungsten in our bones, but our biology can do neither. ]
[Question] [ A very common media technique is to replace area or exchange codes of phone numbers with 555 to prevent people from dialing real numbers and harassing people by accident. However, I find this a bit limiting for my world, since I think a lot can be conveyed through phone numbers. I still wanted to avoid this issue though, and I’ve landed on the use of the hexadecimal system, which provides the numbers 0-9 and letters A-F for me to work with. My issue now comes in justifying this change for a world that otherwise is Earth, for all intents and purposes. I see two options here. The first is to simply handwave the problem away by saying this is how it has always been, but I feel this creates more problems than it solves. The second is the one I want to address here. What is the best way, making the least amount of changes to Earth, to justify the use of a hexadecimal dialing system such that everyone would understand this change by the 1990s and accept it as completely normal? [Answer] The civilization behind those telephones simply uses a base 16 numeral system. Using base 10 is not grounded in the fundamental laws of physics, it's just a convention. Since we are accustomed to it, for us it is totally normal that our phone numbers are decimal and not binary or hex. So it will be for them: they are used to count in base 16, so having number in base 16 is equally logic and straightforward. [Answer] ## Phone numbers are already hexadecimal (kinda) Telephone equipment communicates using a technology called [Dual-tone multi-frequency signaling](https://en.m.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling) - you've probably heard this if you use a landline - the sequence of tones when you dial a number (or just hit a button on the keypad). Under the covers, this technology uses four high frequencies and four low frequencies. For instance to convey the number 5 you use a combination of a 770 Hz and a 1336 Hz tone. Four high frequencies and four low frequencies give us 16 possible combinations. Ten of these are used for the regular digits - 0-9, two are used for the star and hash (pound) sign, and the final four are normally labelled "A", "B", "C" and "D". They're mostly unused in modern telephone networks, but still have wide support (I believe). So, there's the technology - perhaps in your world when the first DTMF phones were being introduced all 16 keys were included rather than the twelve we are more familiar with. Then, when number exhaustion started to be a problem, rather than choosing to extend the length of phone numbers, phone companies assigned numbers including \*#ABCD. This actually is quite a bad idea though - if you have ten possible digits and 7 digit phone numbers that's (at most) 10^7 or 10 million combinations. Adding in ABCD would give you about 105 million combination, or 270 million if you also allow \* and #. In contrast, adding a three digit area code gets you to 10^10, or 10 billion possibilities. [Answer] Here's my answer - Telephone adoption was much more widespread **globally** and this meant that (like IPv4) that all the decimal numbers were used up, switching to Hex added significantly more numbers, whilst still being *reasonably* human readable. [Answer] 1. Area code 555 appears in American movies and *only* in American movies. I have never seen a European movie with anything similar; and I have never seen a written story, American or non-American, with this silly convention. 2. Once upon a time, telephone numbers looked like RIV-1489, with the three letters abbreviating the name of the exchange. 3. Nowadays, when we can type letters and symbols on our mobile phones, there is no technical reason why we cannot use them; for example, //USA/SYR/xxxxxxx instead of +1315xxxxxxx. 4. Even in America, the land of 555, there are [combinations which are reserved](https://en.wikipedia.org/wiki/North_American_Numbering_Plan) and are never used in real life: * [Area codes](https://en.wikipedia.org/wiki/List_of_North_American_Numbering_Plan_area_codes) in the North American Numbering Plan cannot begin with 1. Technically, they cannot begin with 0 or 1; but an area code of the form 0xy would create a lot of complications. * The second digit of an area code in the North American Numbering Plan cannot be 9. * Area codes in the North American Numbering Plan which have identical second and third digit are reserved for special use.Which means that you can safely use area codes 1xy, x9y and most of xyy (except, for example, 911) as area codes in your story with no risk of annoying any real-life telephone user. [Answer] First one should realize that we use decimal digits for phone addresses is arbitrary. When phone addressing was introduced, if we had used letters, or coloured shapes (to reach me, dial red square, blue circle, green triangle), everyone would have though that was normal, and using digits would be seen as strange. So, it doesn't require a huge leap of faith to address phones with hex digits instead of decimal digits. As for a reason, phone numbers tend to run out. My parents have had the same phone line for more than 60 years. And when they first got their phone, it used a four digit local number. But then they ran out of numbers and their area went from four digit local numbers to five digit local numbers in the 1970s. Later, in the 1990s, that wasn't enough and since then they use seven digit local numbers. (This is outside of the North American plan). Now while adding digits is a way to increase the pool of addresses, it comes with a disadvantage. It means everyone phone number changes. Another way to increase the pool of possible numbers is to start using hexadecimal digits. And while this means big changes in infrastructure, it does have one advantage: everyone can keep their existing phone number, as any decimal digit is also a hexadecimal digit. [Answer] ## Binary keyboards At some point in your history, phone numbers had to be typed in binary, because dials had only two keys, or some other reason related to the technology. Writing down long binary numbers, and memorising long binary numbers, is quite a pain. Therefore there is a huge incentive for people to convert between binary phone numbers and another base. Converting back-and-forth between binary numbers and decimal numbers is quite a pain. It's not *hard* per say, but there is no convenient way to do it, you need a pen and paper to write all the intermediary calculations and it is easy to make mistakes. Converting between binary numbers and hexadecimal numbers on the other hand, is extremely natural. Just replace each group of 4 bits by the corresponding hexit: ``` 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 0 1 2 3 4 5 6 7 8 9 A B C D E F ``` For instance, the hexadecimal phone number F90122 corresponds to the binary phone number 1111.1001.0000.0001.0010.0010, and it is easy to convert back and forth on the fly. [Answer] The *simplest* solution is to let AT&T maintain their monopoly for a little while longer. Then they can lobby to have the digit base increased rather than increasing the string length, so they can lease (yes, "lease" not "sell"; AT&T was a strong company) their "new and improved" "full dialing power" telephones. There is precedent for this too. The \* and # keys were not on the telephone dial until AT&T put them there, and there are specialty models that include the ABCD keys that Neil Tarrant explains in his answer. They even sell [16-digit telephone pads](https://pmdway.com/products/16-key-keypad-module) you can use to upgrade you own set up! (not an endorsement, they're just the first one I found that claims to still have them in stock) [Answer] ### Because Western Union Already Did It Nature abhors a vacuum, and people loathe change. Drawing inspiration from the [Font of All Knowledge](https://en.wikipedia.org/wiki/Rotary_dial), it appears that rotary dials are not exactly new ideas in the 20th century. As early the 1830s, dial mechanisms were considered for telegraphy. Essentially, a certain telegrapher would turn the dial first to U, then X then Q, then space-A-K-H. The receiving telegrapher would check his code book and know that the shipment had been placed on the Empress of Canada. In your world, telegraphy has been done with alphanumeric dials for decades. When telephony came on the scene, the inventor simply combined his voice over wire device with an off the shelf dialing device. Dialing of Exchange plus number, e.g., PEnnsylvania-65000 becomes a trivial matter of dialing the two letters, then the five numbers. The exchange system is cool because it gives you an easy to remember alphanumeric address that has expandability built into the system. It's easy enough to make longer alphanumeric exchanges, like SUSquehanna7-4800. In your world, the end user won't be inconvenienced or really even notice anything unusual. With 3,656,158,440,062,976 available telephone addresses using 10 characters, I doubt you'd run out of addresses! Even so, the switch from 212-PE6-5000 to a number like 796f-6e65-2e is trivial. Your end user won't know the difference, except that the familiar exchanges are all gone. Everything would happen at the underlying technological level. The switch could easily be done in the 1950s, to much fanfare as it was introduced at the Worlds Fair. Public service announcements would be produced and disseminated, educating the public about the new hexadecimal service, much like how they did when [dial service was introduced](https://www.youtube.com/watch?v=uaQm30DDHL8) in the real world. You could introduce new dial tones, ring tones and busy tones to alert the caller that she's on the old exchange or the new hexadecimal system. [Answer] **Short answer:** Using Hexadecimal is more efficient than decimal for a telephone system that uses digital logic to connect two telephones together based on a phone number. This is a simplified example, but lets say a decimal digit in my phone number selects a choice for some relays in my telephone system, and those choices are being controlled by digital logic, then I need 4 bits to represent that choice. But digits 0-9 only use 10 of the 16 possible choices for those bits. I have wasted hardware because those 4 bits could be used to turn on one of 16 relays, but I am only using them to control 10 relays. My system becomes larger and more costly to support the same number of customers compared to using hexadecimal phone numbers. **Long answer:** One might argue that the development of telephone systems was a complex task at the time it was first undertaken. In your world the engineers needed to squeeze every last drop of efficiency out of the system to make things fit within the constraints of size, weight, power, and cost. In that case hexadecimal was chosen for the sake of efficiency. Now let's go into why it's more efficient. Early telephone systems were completely analog, with switchboard operators manually connecting people by plugging wires into different holes. The next phase in the evolution of the telephone system is replacing the human telephone switchboard operator with an automatic system that connects the different telephone circuits. That would likely involve relays. Relays are open/closed, on/off. Given that relays are the state-of-the-art technology of the time, and the phone companies are already using them, any other logic that decodes the phone numbers to control the signal relays would likely be composed of more relays. The relays are being used to make **digital** electronics. For electrical engineers who are designing digital computer equipment, number systems that have a power-of-two as the base are typically more efficient. Even more efficient is power-of-two bases where the number of bits used to create that base is also a power of two (1, 2, 4, 8, 16, 32, or 64-bit numbers). Some examples are below. * 2^0 bits = base 2 = straight binary. * 2^1 bits = base 4 (not commonly used anymore) * 2^2 bits = base 16 (hexadecimal) * 2^3 bits = base 256 (the common 8-bit byte) * 2^4 bits = 16-bit numbers (common register size for 16-bit processors) * 2^5 bits = 32-bit numbers (common register size for 32-bit processors) * 2^6 bits = 64-bit numbers (common register size for modern 64-bit processors) Of the above choices, straight binary take a lot of digits to write numbers (about 10 bits for every 3 decimal digits) and is therefore not very compact. Creating a symbol for each of the choices in an 8, 16, 32, and 64 bit number would result in way too many symbols for humans to memorize. That just leaves 2-bit and 4-bit numbers. The 4-bit numbers only have 16 symbols to remember, and one can express numbers fairly compactly (about 5 hex digits for every 6 decimal digits). That of course explains the ubiquitous use of hexadecimal in computer programming and electrical engineering. [Answer] Digital is invented before the telephone. Hexadecimal is very common in computer science and virtually unknown outside of it. Base 16 is great to work with in a digital system. So if digital (not necessary computers as we know them) is invented first and the telephone system is built on that, base 16 would make sense. That doesn't mean computers must be invented first. Maybe just the concept of digital computation and the first phone switches work with binary trees or something. [Answer] When telephone was first created, there were few telephones, which means few telephone numbers, and so telephone numbers were relatively short. As the ubiquity of phones increased, on Earth we gradually added more digits to phone numbers to cover the larger number of phones. On your fictional Earth, instead of increasing the length of phone numbers, they decided to increase the number of possible digits. So, maybe at some point, phone numbers consisted in six digits 0-9, for a number of possible phones of 10^6. On Earth we first extended the number to eight digits 0-9 for a number of possible phones of 10^8, then later to ten digits 0-9, for a number of possible phones of 10^10; while in your fictional world they first decided to extend to six hexits 0-9A-F, for a number of possible phones of 16^6 ≈ 10^7, then later to ten hexits 0-9A-F, for a number of possible phones of 16^10 ≈ 10^12. One advantage of extending to hexits is that already-existing phone numbers don't look too different from new phone numbers. If old phone numbers consists of six digits 0-9, and new phone numbers consist of six hexits 0-9A-F, then old phone numbers and new phone numbers can cohabit with no one complaining that old phone numbers have a different length. Also note that on Earth, every country has its own numbering plan (and the actual length of a phone number varies from one country to the next). In your fictional world, they might have come up with a global numbering plan from the start. [Answer] The extra digits could be used us a checksum, to reduce mis-dials. For example, the classic number ``` 086 543 932 ``` could become something like ``` 086F 543B 932C ``` where the trailing `F`, `B` and `C` characters are a hash of the preceding three numbers, and can be used by the phone to check that the numbers have been entered correctly. Why are people mis-dialing so much? And why is it so important to prevent mis-dials? I don't know, it's your story. Some real-world examples of related concepts: * <https://en.wikipedia.org/wiki/Parity_bit> * <https://en.wikipedia.org/wiki/Hamming_code> This one is smart because it can not only detect errors, but also correct them. * <https://coincodex.com/article/2078/ethereum-address-checksum-explained/> [Answer] It's simple: **in your alternative timeline the [Anti-Digit Dialing League](https://nickvsnetworking.com/the-anti-digit-dialing-league/) won**. This is a real organisation that really did exist and their goal was fighting against "creeping numeralism" in general and the switch to numeric area codes in particular. But in your universe they gained widespread popular support (rather than being seen as a couple of weird guys charging at the windmill of technology, and "numeric" area codes were banned. Of course the reasons behind introducing numeric area codes haven't gone away, so while there was a ban on all-digit area codes, hex was a kind of legal loophole. *(Yes, this whole answer is just an excuse to mention the ADDL.)* [Answer] **This is a [Frame Challenge](https://worldbuilding.meta.stackexchange.com/q/7097/40609)** I can't imagine this shift occuring. 1. Technological inertia is very hard to overcome. Consider how long it took to discontinue including an [RS-232](https://en.wikipedia.org/wiki/RS-232) port on the back of computers. 2. There are many dialing protocols in the world. We in the U.S. too often think the whole world uses the 3-digit area code, 3-digit central office code, and 4-digit line number — but it simply isn't true. 3. How the world's phone number formats developed had everything to do with the development of telephony technology. It's anything but arbitrary — and yet you're trying to make an arbitrary change. We could assume some overwhelming change occured that required *more numbers.* That's the only practical reason for changing the number base (or anything about the number format). More numbers comes about from more population or more ubiquitous use of communication. But the Internet (originally called the *ARPAnet,* started in 1969) and cell phone technology (launched in japan in 1979) are competing technologies that would create a technological drive that would, frankly, never embrace a base-16 solution. Organically, it's more likely that you'd have one of the following shifts. 1. A never-ending extension of the decimal system. Longer and longer base-10 numbers. 2. A base-36 solution based on all English letters and numbers (and that's an arrogant statement) where the "phone number" becomes more compressed to continue to make numbers memorizable. 3. An earlier adoption of the speed-dial/cellphone/DNS solution, where human-readable names are mapped to protocol-dependent addresses (phone numbers). **Conclusion** You're asking us to modify known history to adopt a numbering base without any recognition of the history of communication technology. I can't imagine such a solution believably occuring. [Answer] Here is a very plausible scenario: For this to happen the time difference between telegraph and telephone should be larger, or, telegraph technology got more usage than what we had. This leads to more telegraph adoption, which in turn leads to automatic telegraph switching. Early switching technology uses relays which are binary in nature. Thus with operators being comfortable with codes, it would be easier to handle hexadecimal addresses which does not require mathematical base conversion. Then once the phone is invented, it would use the same switching network with hexadecimal addressing for phone numbers. [Answer] 1. They went digital early on in the development of the phone system. Digital doesn't have to mean electronic computers. Even relays are digital - they are either on or off. 2. They kept running out of phone numbers. An easy mistake in allocating numbers is not to allow for growing towns. You can allocate so many digits for each phone number, only to run out after a few years as the town grows. 3. Rather than re-number all the existing phones with an extra digit, they switched to hexadecimal. Decinal is inefficient in a binary system, as each digit only uses the binary numbers 0000 to 1001. That leaves 1010 to 1111 unused. Bringing those digits into play gives you a whole load of new numbers to allocate without doing anything to the existing ones. [Answer] ### No numbers, at all Why have human-readable numbers at all? You have a computer in your pocket that remembers it for you, even posts it in the cloud so all your current devices and future phones know them too. Replace phone numbers with bar codes, QR codes, NFC tokens, hyperlinks, metadata, or whatever machine-readable solution you want. Then the user just has to tap a button on a webpage, snap a picture of a poster, hover their phone over the front door, and poof, their phone reads the number and saves it. And if for some reason you ever need to write a number on a piece of paper, you could always ask your phone to generate an HEX string representing its number (or the SIM's number more likely), which someone could then type into their phones, and would then store without either of you having to remember it ever. --- To be honest, I don't see a good reason to write out phone numbers in a story, so decimal or hexadecimal or whatever else doesn't matter much there. For a visual medium, you could replace a number with a machine-readable logos. We already have companies mixing their logo with QR codes, so really we're already encoding contact information into company logos, if wouldn't take much to generalise it. [Answer] # Make the change *before* introducing direct dialing The main problem with *switching* from decimal to hexadecimal phone numbers is that millions/billions of existing telephones would instantly become obsolete. You'd have to introduce new [dials](https://en.wikipedia.org/wiki/Rotary_dial) or keypads with the extra digits. However, if you *don't* have to modify consumer hardware, the change is relatively straightforward for the phone company to implement. So, make the change in the very early days of telephony, when end-users didn't dial phone numbers themselves, but had to contact a human operator at a [switchboard](https://en.wikipedia.org/wiki/Telephone_switchboard) to give a phone number. The switchboards themselves would be expanded so that each [exchange](https://en.wikipedia.org/wiki/Telephone_exchange) could handle up to 65,536 phone lines (numbered 0000 through FFFF) instead of the 10,000 (0000 through 9999) that became standard in our timeline. And that would be the justification for the change: To allow more phone numbers. --- Of course, another way to justify hexadecimal dialing is to make your civilization use base-sixteen numbers (perhaps by giving people 16 fingers), thus making hexadecimal phone numbers the obvious choice in the first place. [Answer] ### Your phones don't use phone numbers "Phone numbers" are identifiers in a namespace defined by [E.164](https://en.wikipedia.org/wiki/E.164). However, while nowadays many apps build upon them (to use the phone Contacts), it doesn't need to be so. You could call someone by their [ICQ#](https://en.wikipedia.org/wiki/ICQ), [Skype username](https://en.wikipedia.org/wiki/Skype), [Threema ID](https://en.wikipedia.org/wiki/Threema)... Or perhaps, just email addresses (maybe using [Jingle](https://en.wikipedia.org/wiki/Jingle_(protocol)) over [XMPP](https://en.wikipedia.org/wiki/XMPP#Peer-to-peer_sessions)) At one point in your world, a different system for calling replaced the traditional phones, and everyone moved to e.g. *Skype*. So people use phones (the devices), but the calls actually use a different protocol -originally fueled by a company- that uses a different naming ("numbering") schema. You want this by the 1990s, which is a bit early. There were already solutions like Skype, but they required a computer (non-withstanding the "Skype phones" hardware). I would recommend moving your story timeline later, or accelerating the introduction of smartphones so they happen a decade earlier. If a company introduced an affordable (maybe subsidized?) smartphone a decade earlier, they could have monopolized the market, introducing whatever numbering calling system they wanted e.g. a *BBPN* (BlackBerry phone number) replacing phone numbers. ]
[Question] [ Think Tatooine in climate, but with oceans. Here are a few restrictions due to setting: * There is modern technology, but not too much electricity ie no super high amperage machines. * Population is small at first (only a couple hundred), but is growing since this town has a strong supply of water and other towns do not. * There must be enough water for drinking, showering, and small amounts of farming. Fishing is the primary food source. * The people are mostly very poor and shipping the water is not feasible except for the wealthiest members of the village (one of the themes here is the conflict this brings) * The solution should be buildable by people without lots of money Any suggestions re desalination, condensation, etc are welcome. [Answer] It's a coastal city with lots of sunshine in a modern setting. You have everything you need and more. All you have to do is [desalinate the water](https://www.wikihow.com/Desalinate-Water) and it's done. Took less than a minute research. OK, you have to scale it a little better than in the link. Channel the seawater to shallow fields, coated with water resistant foil to prevent seeping it to the ground. It should be a few cm water in each field. Transparent vinyl (or what it's called) close above it. It lets through the sunlight, speeding up the water evaporation. The vinyl catches the evaporated water droplets and with a slight tilt, they will flow to a prepared storage (or the agricultural fields). The salt remains, which they have to collect, but they can sell it for good money. The amount of water is only dependent on the size of the fields. [Answer] **Qanats.** [![qanat](https://i.stack.imgur.com/iYHhl.jpg)](https://i.stack.imgur.com/iYHhl.jpg) <https://whc.unesco.org/en/list/1506> <https://en.wikipedia.org/wiki/Qanat> > > A qanat or kariz is a gently sloping underground channel to transport > water from an aquifer or water well to surface for irrigation and > drinking, acting as an underground aqueduct. This is an old system of > water supply from a deep well with a series of vertical access shafts. > The qanats still create a reliable supply of water for human > settlements and irrigation in hot, arid, and semi-arid climates, but > the value of this system is directly related to the quality, volume, > and regularity of the water flow. Traditionally qanats are built by a > group of skilled laborers, muqannīs, with hand labor. The profession > historically paid well and was typically handed down from father to > son. According to most sources, the qanat technology was developed in > ancient Iran by the Persian people sometime in the early 1st > millennium BC... > > > Qanats are super duper cool. They are ancient engineering marvels which still do what they are supposed to do millennia later. These underground aqueducts move water from distant sources (often miles away!) to arid lands and offer a bunch of side benefits - in addition to clean water, qanats can provide cool air. Read on how having a qanat pass under your house offers cool air pulled up thru the house via a chimney. [Answer] An extreme possibility, which requires some suspension of belief: This town lives in a small plain surrounded by mountains. Local winds bring heavy fog 24/7 which is trapped in large collector/condensers. [Answer] > > **September 2019 update briefing:** it turns out that desalination is becoming more scalable by the day. This kind of changes the answer depending on the fine tuning of the restrictions set. > > > **Actual solutions** used in the coast of the **Atacama desert**: * [Fog collection](https://en.wikipedia.org/wiki/Fog_Collector). The wind from the sea does bring some water, which you can collect, but it's limited, not very scalable. **Older Update:** limitations of fog collection include the maximum water content of fog (saturation) and fog collector efficiency (which depends on wind speed). Also, according to the OAS: *Their water supply can still be contaminated by windborne dust, birds, and insects. The moisture collected can promote growth of mold and other possibly toxic microorganisms on the mesh*. As a rule-of-thumb reference, [this paper](https://www.sciencedirect.com/science/article/pii/0169809589900367) states that in optimal conditions a fog collector can theoretically collect 75%-95% of the water content of air at wind speeds between 2 and 8 m/s. Unfortunately these conditions **worsen** with bigger size of the collector. Assuming the best throughput takes place at top speed AND with a decent content of water in air (usually ranging in the [grams/cubic meter](http://www-das.uwyo.edu/~geerts/cwx/notes/chap08/moist_cloud.html), say 10), you get a few dozen grams of water per sqare meter of collector per second ($8\times10\times.95=76\,g$), but can optimal conditions be sustained all day, all days? Typical throughput in the Atacama desert (I assume desert=dry, Atacama being one of the driest, though) is [around $5\,lt$](https://en.wikipedia.org/wiki/Gar%C3%BAa#Fog_collection) per square meter of collector per day. * Desalination of seawater ~~is still expensive, not very scalable. You can lower standards (taste, purity) to get a little more water, which could fuel your conflicts. Military sea vessels get water through desalination, using a combo of temperature, osmosis and pressure (thanks to their engines).~~ > > **Update 2 (September):** it seems that technology is advancing faster than I was aware. According to [this news outlet](https://www.futuro360.com/videos/planta-desaladora-antofagasta-tranforma-agua-de-mar-potable_20190323/) (in Spanish, linked to the Chilean branch of the Turner group—CNN), [Antofagasta](https://en.wikipedia.org/wiki/Antofagasta) would have 100% desalinated water supply by 2020. Antofagasta is a 300,000+ inhabitants coastal city in the middle of the Atacama desert, whose main economic activity is related to mining (mainly copper.) **Caveat:** the article does not cite any sources, and its wording is ambiguous: It first says that current supply covers 80% of the demand *in the neighborhoods served*, by Aguas Antofagasta (the local supplier,) which might mean not the whole city. See [here](http://www3.aguasantofagasta.cl/empresa/ruta-del-agua.html) for an article by Aguas Antofagasta about their current collection process, including **desalination** (also in Spanish.) > > > Regarding the amount of electricity demanded by the process, there is little information given by these sources: they say 1) water is pumped from $400\,m$ from the coast, $20\,m$ below sea level (this requires energy, not necessarily electric,) and 2) water is desalinated through inverse osmosis; this is probably sped up by increased pressure (which also requires energy.) Anyway, **the fact that its currently being scaled for tens or hundreds of thousands of people, means it probably satisfies most of your concerns**. > > > The main question now would be why other cities don't have the same supply of water. It could be that the local economic activity is what makes water desalination economically feasible. > > > Other: * Pipes from oases. * Underground streams. * Water trucks. **All in all, technology from a few years ago, would limit your settlement's population**, unless you can bring water with pipes or something else, but it's becoming less of a problem today. FWIW, when I was a kid, cities in the Atacama desert relied on external sources, and needed to ration water. [Answer] > > @Lupus just reminded me that I should pay a LOT more attention to other answers! His answer is this answer and it was posted before mine. Please go upvote his answer! It's a good answer! Thanks! > > > **Behold! A time-tested method for desalinating water** [Wiki how](https://www.wikihow.com/Desalinate-Water) shows us a modern method similar to that I used as a teen in the Scouts. (Image from Wiki How.) [![enter image description here](https://i.stack.imgur.com/jlWcpm.jpg)](https://i.stack.imgur.com/jlWcpm.jpg) The process is simple: evaporate the salt water and let it condense on plastic, then drain the plastic someplace useful. [Here](https://www.youtube.com/watch?v=rUET3PnPZng) is a video showing how to do it with some plastic bottles found on the beach. [Here](https://www.youtube.com/watch?v=10k-DPcLrHU) is a video showing a larger operation. This system can be easily scaled so long as you can support whatever material is being used to condense the water. Honestly, it's conceivable you could do this over whole acres, letting in seawater through a gate and draining into a cistern. [Answer] Assuming your oceans are salt water, these are a few ideas that occurred to me: Use wide-bandgap semiconductors to perform photo-electrolysis -- separating the hydrogen and oxygen using photons ( 2 photons + 2 H2O -> 2 H2 + O2 ). This is a technical possibility today, the development to make it engineering solution is still in progress. Then, ignite the gases and you have pure H2O again. Evaporators: The village has dug channels for water at high tide to fill wide shallow ponds enclosed in plastic tarping. The heat of the sun evaporates the water, leaving the salt behind, then water is condensed in shaded metal tubes that act as heat exchangers -- looks like large stills Orthographic lifting + modified natural caves + passive heat exchangers: The village sits on a wide peninsula surrounded by mountains that funnel the air higher and higher to a canyon or pass at the top. The mountains are honeycombed with natural caves, that people extended using explosives so they open on the other side of the mountains. The moist winds are cooled as they rise -- a consequence of orthographic lifting -- and air going into the caves is cooled further. The water condenses in underground reservoirs. This all only works because of the strange and unique geography and limestone or sandstone mountains in this area. [Answer] [![coal](https://i.stack.imgur.com/Ty9qD.jpg)](https://i.stack.imgur.com/Ty9qD.jpg) **Make water from coal.** I proposed this to Innocentive as a way soldiers could make water for themselves in arid climates: condense it from vehicle exhaust. The cleaner your carbon source (natural gas would be ideal for this) the fewer contaminants will be in the water you will make. Assumptions: 1: This is a planet with an oxygen environment. 2: There are hydrocarbons like coal available to be burned. The formula for oxidation (burning) hydrocarbon is CH4 + O2 -> CO2 + H2O <https://energyeducation.ca/encyclopedia/Hydrocarbon_combustion> The big fluffy white plumes one sees coming from the smokestacks of coal plants are mostly water steam, produced as the product of combustion. Some napkin numbers: considering a pure carbon hydrocarbon (more like coal than natural gas) you get 2 moles of water from every mole carbon burned. That means 1 ton of coal can be burned to produce 226 liters of water. A human needs to drink about 2 liters of water daily. You would definitely want Israeli-style water conserving agriculture in a situation like this. You would need a readily available carbon source like coal or oil to burn. You would need a way to condense the steam and then possibly distill it again to remove contaminants from your hydrocarbon source. As regards distilling you fortunately have a heat source you are not using for anything else: all the burning coal. [Answer] **Aqueducts** Aqueducts have been used for thousands of years to get water from one place to another. No modern tech needed nor materials but it would help speed up construction. The [Roman Aqueducts](https://www.britannica.com/technology/aqueduct-engineering) were up to 57 miles long and some are still in use today. They can be built of stone or timber. The OP states this town has good water but other do not which means it has to have something others don't have. Desalination and/or condensation plants can be built at any town and in fact the other town would build their own [Answer] If this is set in the near future, **desalination** plants should be an option. The main requirement is lots of electricity. They have lots of sunlight. At present the capital cost of solar PV panels may be prohibitive for a poor community, but this is because of the nature of Silicon solar cells. We already have **perovskite** solar cells working in the labs. The goal is a solar panel that can be manufactured almost as easily as spraying paint onto glass. So set the story in a future where that goal is realized, and where solar panels are as cheap as glass windows. That in turn will drive the cost of the rest of the desalination technology way down. As per other answers, you can do low-tech desalination with just plastic sheeting, and sell salt as a bonus. But agriculture is thirsty. I rather doubt you can desalinate enough water for subsistence agriculture that way. Perhaps they only need vegetables as dietary supplements, and get the majority of their calorific intake as fish/ seafood? (If you relax the "no aquifer" constraint, you can have deep-rooted crops such as grape vines, which can pull up water from very many feet underground. Perhaps a low-permeability aquifer, which is not useful if you dig a well into it, but which such plants can use). [Answer] As others have mentioned fog/moisture capture and transport from other regions, but perhaps something to compliment... how to maximize the impact of what water you do have. The design of spaces and usage of plants to create micro-climate effects to maximize water impact. Consideration of succulent type plants for pioneering/climate modification. So, regarding plants/micro-climate. If you've produced an enclosed space and have grown trees these are beneficial because you moderate the exposure to the sun. If you look at that image of the qanat, this is indicative, the trees shade the ground and water, minimizing the evaporation of what is there. The more shade you have, the more you conserve what water you do have. <https://forestsnews.cifor.org/10316/make-it-rain-planting-forests-to-help-drought-stricken-regions?fnl=en> <https://en.wikipedia.org/wiki/Desert_greening> Furthermore, the trees will buffer wind, and can themselves capture a bit of moisture in the air, and of course slow down evaporation. On a larger scale, trees actually help to produce rain, as they do breathe off water themselves. Consider this, if there is moisture in the air, but not enough to rain... as this moisture passes over a forest, where trees are breathing off moisture, the combined effect of the ambient air moisture + tree breathed moisture, combines to produce enough total moisture to cause precipitation (enough water combined will fall as rain). So downwind somewhere you'd probably want to consider capture and some sort of piping/aqueduct, like the qanats. And send that moisture back to your cultivated forests upwind. This could be an expanding system that, although fragile, could be something that would slowly scale. More trees would shelter more land/water, and breathe more moisture, which would interact with the evaporated moisture from the sea, which could precipitate, leading to more water to pipe back to said trees, which could be expanded to shelter/breathe more moisture, interacting with more sea moisture, etc.etc.etc... Anyhow, regarding succulents. There are various species of plants, like cactus, and these are of course species most adapted to low moisture levels. <https://en.wikipedia.org/wiki/Succulent_plant> These could be interesting considering a systematic approach to the landscape/microclimate and if you used the tree/shade/moisture model, could be used as a notion of "pioneering" species. So before you plant trees, you have cacti and other succulents, helping to intercept moisture/attract animals and shade the ground. Every bit of shade/water interception counts in this model. On top of that, if you consider what "agriculture" means, there are succulents that are used in that regard. Consider agave: <https://en.wikipedia.org/wiki/Agave> Agave can produce food, and of course is used in tequila production. Furthermore, there are plant species that are highly salt tolerant. These could utilize some of the untreated water. They would again be able to provide shade/animal habitat, and would themselves contribute into the water feedback loop described above. <https://www.gardeningknowhow.com/special/seaside/gardening-salt-water-soil.htm> Considering the availability of salty water, these salt tolerant plants + succulents could help form the "outer boundary" and pioneer the land, helping prepare for a slow adaptation of regular trees/plants to enter the space as water is available to irrigate. So, in total, this is a multi-dimensional approach to the usage/protection and increase in moisture, rain production, capture, and forming a slowly scaling feedback loop to promote more and more rain production/interception and water presence in desert greening type of way. If you combine this sort of "perma-culture" approach with the technological captures/transport described by others, you could have a more holistic approach to water production/capture/conservation. Hopefully that is inspiring, and not just in your fiction, but also for real life. [Answer] (Edited) Well, even if there is almost no rain, there still may exist *some* rain. People can dig large holes or build containers in which they store water from rainy periods and use it along the year. Some people make that in semi-desert areas in Brazil, however the water is not enough for luxuries such as baths and in your case would need some complement. Also, it's possible for the desert to have underground water sources that can be accessed via wells. These sources are basically like "underground rivers" that are born in far away areas where the soil absorbs more water. One other thing that I could think is the use of plants. Desert plants are good at retaining water, so maybe you could have a special plant that can get water from very lower levels in the soil and be used as a water source. I don't know, though, how much of these plants would be needed to supply a person and if it would be enough. The other option is desalinization. People are saying it's viable and kinda easy, but as far as I know, it's usually costly and used when nothing else works; a last resource. However, if your society really depends on it, they may have worked a way to make it cheaper and easier. Many of this options can change according to other aspects of your geography, of course, like mountain ranges and hidden underground water sources. [Answer] If the city is located close to the sea, the winds blowing from the sea inland will carry some humidity. Overnight the falling temperatures can lead to the humidity condensing, therefore a series of drapes oriented parallel to the wind direction can act as condensing surface, letting then the water flow into channels to a reservoir. [Answer] I’m going to challenge you on the shipping water. Oil costs \$0.5-0.75 per barrel per 1000 miles via pipe, \$4.25-5.50 per barrel per 1000 miles via train, and \$1 per barrel per 1000 miles via boat to ship. An oil barrel is 42 gallons. This gives us a price of \$0.01-0.13 a gallon of oil per 1000 miles. If water costs the same as oil because it is shipped from other countries, this would mean water would cost the same price to be shipped, plus an additional cost of basically nothing for water. Now, if you are willing for people to act like we do, people could be using 100 gallons of water a day. This would cost a citizen about \$1-13 a day per 1000 miles, which is considerably high, but manageable for everyone. This leads to a question of how to weed out other towns. A simple method is to have your town have a good military or good strategy to protect the water shipments. Water shipments are much more valuable than oil and would of course be targeted by enemies. A big side effect of military control of the water is that important people have control of the water supply, so perhaps your wealthy individuals control this (or do whatever would happen to create planned conflict) and they continue to have good water. [Answer] # Presence of coastal cave systems If your desert is set on a plateau and that the coast is very high compared to the water level, then the water could had eroded the rock and created the cave system. Such cave system would channel wind underground and condense the air moisture from the sea into underground pool. The local population could have then carved the rock and created part of an underground city (think Mesolithic underground cities as seen in middle east). The speedy, moist winds would also provide cooling and air that would be less harsh compared to that of the desert. It would be very like Dune sietchs with their wind trap, except that it would be much more successful on the sea shore. [EDIT typo] [Answer] There could be springs of fresh water just off the shore. This would create pools of brackish water off the shore that would be pottable. I am struggling to remember the details of something I read but somewhere in Polinesia or another series of islands it was discovered that there were such just off shore pools. They were identified as in use by anchent cultures as both inland catchment basins constructed by digging pits for rainwater or land springs and some beaches had similar carvings facing the pottable water. Until someone tested that salinity of the off shore water they could not explain what the carvings that marked drinkable water were facing the sea. Turns out the underground rivers were exiting at known locations and the fresh water was not well mixed with the sea water when it reached the surface. If you new where to go in your little boat you could get barrels full of slightly salts but healthy to drink water. Your city could be on that lucky bit of the coast. Row a few meters off shore to the right spots and you can fill your boots so to speak. This could be the only location on the coast with such a resource which then explains how this city has a suffit but no others do (as anyone on any coast can desalinate and will pinch the idea and tech before long). [Answer] A double-purpose greenhouse-desalinator is a good idea. Think of using greenhouses with evaporative cooling system. However, [the only source of water is from the sea](http://innovatedevelopment.org/2014/08/21/under-the-sea-water-greenhouses). The water is not directly used for irrigation. It is used for creating a cooler and humid environment. The air outlet is humid and is a source of water by condensation. Advantages: Low-tech (Relatively), uses less energy, serves for two purposes without excessive energy consumption. Note that the desert is very similar in its climatic system to the ones in the Arabian peninsula area, from the east gulf to the red sea. There are no rising thermals which cause rain and the air is dry. This means the evaporative coolers will work very efficiently if you need a much cooler greenhouse for crops. ]
[Question] [ A long-running concept I have for my fantasy continent of Diggoran is its isolated and unequalized technological and industrial progress. By ''isolated progress'' I refer to the fact that Diggoran's technological and industrial progress barely extends to the rest of the world which is largely pre-Industrial. Diggoran itself has unequalized technological progress meaning that some countries are in the 2040s while others are in the 1980s and even 1800's to 1700s. My question is how could I possibly justify this wild lack of industrial equality between the nations of Diggoran? Especially when the nations of Diggoran are all part of an EU-like union and more than open to civilized trade and political relations. This EU-like union is known as ''The Empire,'' and it has existed for over 2,000 years. One suggestion I received a long time ago was simply making the Empire weak and barely functional, ruling over the continent only in name kinda like various periods of feudal Japan. The problem with this is that ''The Empire'' is supposed to be portrayed as a great union of peace, harmony, and progress before it collapses thus depleting the continent of stability. The Empire could potentially be a strictly militaristic force, keeping historically incompetent nations stable in its wake while providing little more aid, but I think this idea may have several flaws unless someone can prove the idea as functional. I know the real world has diverse technological progress, but as far as I am aware, there isn't a nation on Earth that is completely lacking in industrial development or electricity and yet retains global prominence or political stability. Sure there may be tribal and rural regions with lower levels of development than the epic-centers of their national civilization, but surely these count as exceptions, right? Most countries have features like that. I think Diggoran is a bit more extreme. I think Africa is a good example of technological inequality, but specific historical events made Africa what it is today. Diggoran's history is not similar to Africa; it is a self-sufficient and self-sustaining Continent which has never been invaded by a foreign superpower. It has done all the invading despite its geography invoking little to no need for resource motivated imperialism. Should I make the difficult decision of getting rid of the Empire or at the very least making all the nations technologically equal to some relative level? Any Ideas? [Answer] A couple ideas. When powerful nations join unions like that they do so for their own benefit and will generally include clauses that are meant to keep their advantages. So perhaps the the price of joining this union for the less advanced nations was that they would not progress enough to challenge the advanced nations. Not quite sure what setting this world is in, but perhaps the only power source isn't portable. Giant magic crystal, alien reactor, crazy lightning field or whatever. It can power the 2040 folks but starts to fall off by the time it is transmitted to the 1980s folks and there's nothing left by the time it gets to the 1700s areas. Electromagnetic hypersensitivity. It's probably BS in the real world, but perhaps in yours the people in the 1700s areas have it as a genetic trait and simply being around electronic devices is painful. The people in the 1980s area have it to a lesser degree and maybe only feel pain around things like wifi signals and whatnot. [Answer] Religion would factor in heavily, Take the Amish for example their technological development came to a complete stop due to them choosing not to progress because of their faith. And look at how technology was stunted in times/areas where religion became more important then science. But even without religion culture can have a heavy influence on the technological development. A culture that for example does not allow women to study will always be lacking manpower on the development front. [Answer] You don't need to explain it, because that's already happened in Europe not too long ago. While the european nations were running toward WW2, building the Stukas, the V2 and all similar feats, in the south of the continent there were regions still living in conditions similar to stone age: a single room carved in the rock, where parents and 10 kids lived together with sheeps, donkeys and chickens, dumping their waste in the path outside the door. This is how the life was in [Matera](https://en.wikipedia.org/wiki/Matera), Italy, until they forced the population out in the Fifties. > > The Sassi originated in a prehistoric troglodyte settlement, and these dwellings are thought to be among the first ever human settlements in what is now Italy. The Sassi are habitations dug into the calcareous rock itself, which is characteristic of Basilicata and Apulia. Many of them are really little more than small caverns, and in some parts of the Sassi a street lies on top of another group of dwellings. The ancient town grew up on one slope of the rocky ravine created by a river that is now a small stream, and this ravine is known locally as "la Gravina". In the 1950s, as part of a policy to clear the extreme poverty of the Sassi, the government of Italy used force to relocate most of the population of the Sassi to new public housing in the developing modern city. > > > [Answer] A modern example of very unequal technological development is **[the Amish people](https://en.wikipedia.org/wiki/Amish)** in North America. They belong to the religious order similar to Mennonites and disdain modern technology, choosing to live without electricity or engines. This culture, which numbers about 342,000 people distributed across the US and Canada, with the largest group of almost 80,000 in Pennsylvania. It survives because their host countries accept amd protect them. A similar example is [the Samí people](https://en.wikipedia.org/wiki/S%C3%A1mi_people) of northernmost Europe. Diggoran might have one or more similar cultures that choose to life at a low tech level, protected by the Empire. In addition to this, there might be outlying regions where high technology simply hasn't reached, similar to how Kazakhstan hosts both the spaceport Baikonur and nomadic sheep breeders living in yurts. Such regions could be isolated behind tall mountain ranges or simply hold no resources that have made it worthwhile developing them. [Answer] The world today (and 200 years ago, and 2000 years ago) had extremely un-equal progress between various nations/tribes and continents. The excellent book "Guns, Germs, and Steel: The Fates of Human Societies" by Diamond is basically an exploration of how inequality developed due to the worldbuilding setting of the real Planet Earth. To hyper-summarize, 1. Hunter-gatherers become agrarian farmers when evolution and climate provide healthy grains and vegetables suitable for domestication. This primarily happens in temperate zones, and evolution has more area to generate more species on landmasses with long East-West latitudes (like the entirety of Eurasia). 2. Agrarian farmers become city-dwellers when they domesticate animals that can be used for food and transport. Only a few animals qualify (they must be large, herbivorous, docile, breedable, social). 3. Cities with food surpluses that allow some members of society to specialize and increase technology and trade. This includes mining and a large tech tree needed to develop efficient metallurgy and highly-effective weapons. 4. Dense cities (with enough people going in and out, living close to animals, and in unsanitary conditions) breed plagues and disease to which locals become resistant. 5. Geography that favors some limited balkanization (mountains, coastlines) will result in smaller nations that will, through competition, develop better policies than geography that favors stagnant empires. 6. When populations with more effective farming, higher technology, and harsher plagues compete with populations that lack these advantages, the victims adapt or die. At some point, though, transport and military technology will lead to exploration. You need to come up with some reason why your 2040s society isn't colonizing or trading their tech with the 1700s societies. You've got a few caveats: > > Diggoran itself has unequalized technological progress meaning that some countries are in the 2040s while others are in the 1980s and even 1800's to 1700s....Especially when the nations of Diggoran are all part of an EU like Union and more than open to civilized trade and political relations. > > > Not to mention the pre-industrial civilizations across the ocean. Why hasn't that trade equalized these countries? Are they newly aware of each other and still in transition? > > This EU like union is known as ''The Empire'' and it has existed for over 2,000 years. > > > Nope, they're not in transition, at least on human timescales. If there is trade and tech disparity as we understand the terms between inequal nations for a long time, the two cultures will eventually homogenize. Something has to give. Is there a Star Trek "Prime Directive" that prohibits a 2040s farmer from setting up a farm in the 1700s country with his modern tech? In that case, who enforces the directive - you don't have a continent, you have an ant colony. Are there impassable mountains cutting the continent into isolated regions with isolated climates and species, and only infrequent and expensive messages can be sent back and forth? In that case, you don't have an empire on a continent, you have separate nations that happen to talk occasionally. Does one area have geography good for farming, but no metals to mine, and another the inverse? In that case, you have idiot merchants who don't know how to trade. Look at Guns, Germs, and Steel for ways that inequalities between nations to arise, but be aware that the natural outcome is for those inequalities to be broken down. [Answer] # There's some sort of magic at work. This isn't tagged science-based or anything like it, so blaming unequal tech development on magic is within the scope of the question. As for how it does so, there's a number of possibilities. Perhaps some of the societies might utilize magic to replace or augment technology, like the Iron Kingdoms of the tabletop wargame Warmachine/Hordes. Perhaps higher technology was present in the past, but it's been lost in many places; this might be because of something like a nuclear war, where much of society was destroyed, or it might have happened because the laws of physics that allow high technology to work have broken down in much of the world, like in the RPG Godbound. Maybe reality is shaped by the dominant paradigm of the people living in an area, like the RPG Mage: the Awakening, and there are reality zones where high technology doesn't function and zones where magic doesn't function. [Answer] **Environment** The environment in the developed nations have historically been hostile, while the less developed nations have had preferable climate and land. The hostile environment have pushed for technological advances in order to mitigate the dangers of the environment, as well as being needed for comfortable living. If there have been little fertile land it has pushed for maximizing the yield from the limited land. If the cold kill people during winter it has pushed for insulated homes and better clothing. If a lot of people got sick, it would have pushed for better medicine. Constant fighting over resources would push for better weapons and military. On the contrary, the less developed nations have had few issues. The climate have been temperate with a lot of fertile land, and there were few diseases and wars, they would have had little incentive to improve and develop new technology. They could have been prosperous simply from farming and valuable metals without practical use. - Changes in climate could then change the dynamic, making the previously welcoming environment more hostile, and the previously hostile environments more or less hostile. The collapse of the empire can come as a result of the new dynamic as a result of change in environment. People are often happy within the status-quo, which now changed. [Answer] Trade secrets. The advanced nation has laws against sharing advanced technology, and its inhabitants are generally convinced that all the other nations are inhabited by lazy, stupid people who couldn't possibly build steam engines. If the advanced nation has some kind of feudal guild system, having the guilds keep trade secrets is a fairly natural scenario. The idea that people should share advances in science is a relatively new one in history; for example, in the 16th century Tartaglia kept his discovery of the formula for the roots of a cubic equation secret, and it wasn't made public until a rival of his, Cardano, who had learned it somehow, published it. [See this webpage](https://www.storyofmathematics.com/16th_tartaglia.html). Probably, the other nations are slowly catching up by stealing the trade secrets. However, the advanced nation is keeping ahead by leaning on their governments to discourage technology. Furthermore, the advanced nation is also making further technological advances. [Answer] **The Prime Directive** Perhaps The Empire has something akin to Star Trek's Prime Directive, and prohibits one nation from interfering with the development of others. Something like this would almost have to be enforced, because otherwise those high tech nations would be spreading out in search of resources, trade opportunities, or simply out of curiosity, and spreading their technology with them. [Answer] **Some people don't get it.** Your backwards folks are put off by electronics - things with working parts too small to see, things where you cannot poke your head in and see what is happening. It just does not sit well with them. These folks are considered slow minded by the technologically advanced people and maybe they are. Maybe they call themselves Slows. They are not ashamed. These slow folks do have their own skills - they have intuition about soil and earth and are great with animals and plants. Their technologically backwards nation is an exporter of agricultural products. Non-slows make mistakes (sometimes systematic mistakes) with their farms that would never happen on a Slow farm. If a Slow visits such a farm, she will be surprised and if asked she might point out how things might be better, but it will be difficult for her to explain exactly how she knows or how she figured out what was going on. If you press her, she might wind up dancing and singing a song by way of explanation. Slows think differently. As noted by @John in his comment, a problem will be bleed - tech creeping in with tech minded persons. You could make the Slows a different species - maybe a nonhuman or maybe something like a Neanderthal. Crossbreeds with Sapiens are possible but often infertile. Slow societies can be difficult for non-slows to live in, for reasons that you could explore in your story if you are inclined. --- Here is a short story of my own featuring a group of such people. <https://www.fictionpress.com/s/3341845/6/Isis-and-Augi> [Answer] # Commerce In fact, a nation sitting in commerce *routes* are know to have unequaled level of civilization development. With great commerce then is possible do private (and public) mecenas to finance artistic and technological innovations. To make the nation somewhat isolated, natural barriers or small territories "nation city" will do. In your case, a continent nation is isolated by water, and can be a convenient position between various ocean routes. It's not a coincidence what major cities are in major routes and have big ports. [Answer] I'm going to throw out two wild ideas. They may not fit your world. 1. **Localized tech boom**. One or more of your nations could have come in contact with something that allowed their technology to advance rapidly. This could be an alien civilization, ancient technological writings from a previous civilization, etc. This allowed rapid advancement some nations. The source of the tech boom could be a guarded state secret. Eventually, the tech level will even out. It's inevitable. But if everyone was at 1800s level tech until a relatively recent discovery/contact, then there could be a period of incredibly unequal tech levels. 2. **Resource availability**. Indistrialized nations require resources to function and continue advancing. Think coal, oil, copper, uranium, etc. If those things were unequally distributed and the nations that had them did not trade them for strategic purposes, you could end up with a big tech disparity. [Answer] ## Lack of conflict For whatever reason, the advanced 2040 group doesn't feel the need to take anything from the 17-1800s groups. Not their land, not their resources, not their people. The more primitive groups don't feel the need to catch up (readily available resources make it unnecessary, no conflict means no need for better weapons/defenses). Why? ## Reasons * Something relatively artificial like ideology/religion (prime directive, venerate the honorable primitives, whatever). This usually feels like something slapped over a plot hole rather than something which evolved naturally. Given that we're reverse-engineering a world here, I guess everything falls into that category. Meh. * Fear: We think those primitives could do something terrible if they wanted to. Plague, Kaiju (giant monster), divine wrath, whatever. * Surprise * A nigh-fanatic devotion to the pope * Free exchange of population: It's all really the same society, but different people have different preferences. See "Amish". All the chillax types end up in primitive-ville, while the brilliant/driven people end up in tomorrowland. Because people can move freely between them, any conflict between them would basically be a civil war, and therefore terrible and worth avoiding extra hard. * Uninhabitable. Natives of tomorrow land can't survive in primitive-ville (and visa versa?). There's something in the air, water, or soil that prevents tomorrowland-ians from surviving unprotected for any length of time in primitiveville. Maybe too much of this gas, not enough of that, something tomorrowlandians are horribly allergic to, or is strait up toxic. Now why does 1980 survive alongside 2040? Same tech level with vastly different available resources? Maybe BigHairington (1980sville) is more warlike and has a much larger population than Tomorrowland. Mutually assured destruction worked out in the real world, at least so far. BigHairington still has WMDs and bioweapons, and would be more inclined to use them because they'd have to. [Answer] **Sufficiently Advanced** The Technological society spent a very long time being insular before striding onto the world scene. They've had industrial revolutions, digital revolutions and are now well into the nano-tech scale technologies we have today and more! They are simply so far ahead that other societies have no chance whatsoever of catching up. If you took a laptop computer back in time 100 years, the very best scientific minds of the time would *maybe* be able to discern some few elements of its operation using the finest tools available. They don't have electron microscopes to see the activities of a modern microchip. It's functionally a tiny black box that "does stuff" Literally black-box technology. That's to say nothing of the more esoteric aspects of our modern industrial society. Frankly, taken without its infrastructure, most elements of modern society will simply not be applicable to a society with 18th or 19th century technology. They do not have the tools to make the tools to understand the operating principles (let alone actually produce) the futuristic marvels of your Future-tech society. Said society has no interest in teaching the foreign savages, nor in sharing more than the odd tidbit or gifts of technological toys (like gifting Rayguns for the royalty of a friendly nation) They also stamp down hard on anyone attempting to reverse-engineer their technology, they take their patents and intellectual property seriously! On the other hand, they've also undergone an enlightenment of sorts and have little interest in taking over the less advanced nations by force. So they hold everyone at arms length, enforce the peace where necessary and generally act aloof and superior. [Answer] It is natural for the world to have continents with different levels of technology, for continents to have countries with different levels of technology, and for countries to have regions with different levels of technology, and for regions to have sub regions with different levels of technology. the world has been that way for thousands of years. At the present time all the formerly separate civilizations have merged into one world civilization. In even the most backward regions people with enough money can acquire the most advanced technology from the most advanced regions. But in an advanced nation like the USA there are probably many poor urban and rural neighborhoods where access to the internet, for example, is much more restricted than in rich or middle class neighborhoods. There are still a few uncontacted stone age hunter gatherer groups in remote areas in the year 2020. There are some religious groups who for various reasons renounce or restrict the use of many advanced modern technologies. So communities of those religious groups are less technologically advanced than their neighbors. Many countries at the present time are rapidly developing, but still have large proportions of their populations living as peasants in villages with little interaction with the technologically advanced parts of their countries. So if there is some sort of Empire or Federation ruling your fictional continent, spreading advanced technology should not be an important function of it. Otherwise it might have spread advanced technology too much and too well for there to be the large differences you want for your story. Thus one might suppose that the main or only purpose of your Empire or Continental Union or United Nations might be to maintain peace among the various nations, countries, kingdoms, republics, city states, fiefs, principalities, tribal governments, provinces, cantons, etc., etc., etc. that compose it. So its main function might be prevent wars, civil wars, and other forms of mass violence. If two groups start fighting, the central government might invade and attack both groups until they give up and make peace. The central government might restrict the access of the subordinate governments to advanced military technology, so that it could easily defeat any government that defies it. But on the other hand the central government might not have a strong enough military to take over direct control of all the subordinate governments and fight all the guerrillas who might rise up in rebellion, so it might leave them with almost total control of their internal affairs. And some of those subordinate governments might want to develop their territories and become as advanced as they can, except in military technology, while other of those subordinate governments might want to avoid developing and industrializing, and other subordinate governments might not have enough control to start large programs for development, industrialization, or acquiring advanced technology. [Answer] Most artificial barriers to progress are overcome sooner or later. State secrets leak, trade secrets are sold, new technologies are interesting. The primary channel of exchange between nations has always been trade. This is how Marco Polo went to China. That is how Arab nations knew of northern European tribes in the 10th century. What stops trade are natural barriers, to some extent, cultural barriers to a very low extent, religious barriers to a low extent - somehow, merchants tend to overcome all of them if there is a deal to be made. What you will need is a **combination** of them to be effective over a long time. A mountain range inbetween with dangerous wild tribes and a religious taboo to enter the holy mountains or something. [Answer] As I noted in a comment, I fear you may have one good idea too many and need to drop one to have a successful story. That said... Let’s posit that the technological differential — imposed by the originally strong Empire — is what caused the break up. In particular, the technological specialization imposed by the Empire created/strengthened the nations, which eventually spiraled out of control as different nations asserted their different powers and shattered the Empire. For example, one area of the continent may have had much more fertile conditions. The core of the Empire might’ve originally been traders who controlled the food trade, turning the fertile area into the bread basket of the continent. The fertile area came to view themselves as The Farmers and eventually coalesced into a prosperous nation. In like manner, a more volcanic area — which had the appropriate deposits and volcanic heat — was the first to make advances in metallurgy. The Empire used The Farmers food to gain exclusive access to the Miners early metals, which the Empire used as weapons and also provided metal plows to the Farmers — but not weapons. Any Farmer foolish enough to try to modify or repair a metal plow might... disappear. Through ruthless control, assassinations, and other mostly shadow-craft the Empire made sure that no one cut out the middle man (themselves), retaining their power over the emerging nations. It’s entirely possible that the Empire might stunt the Miners to keep them in the Iron Age. Meanwhile the Empire might establish an advanced metallurgy project in a remote area near the appropriate deposits, and using knowledge of intensive heating methods from yet another area. This eventually becomes a fiefdom, then a nation, all under the Empires ultimate control. The Miner technology is now old-school, but still quite usable for trade among the Empire’s less-advanced nations (who are not allowed to have anything more advanced than iron) or off-continent. The core Empire, of course, always has the most advanced technology, and works hard to keep others at lower tech levels, to the extent it can. But eventually there were too many centers of power who thought they had leverage over the empire and when the Farmers decided to withhold food things spiraled out of control as a flurry of expansion and partnerships — often fleeting and illusory — sprang up. (I’m imagining a galactic-level empire trope scaled down to a continent.) [Answer] **Non-interference in local affairs allows member states of the Empire to pursue poor economic policies that lead to stagnation.** You wrote: > > Diggoran itself has unequalized technological progress meaning that some countries are in the 2040s while others are in the 1980s and even 1800's to 1700s. > > > "Technological progress gaps" spanning 60 years are not that unprecedented in history, especially considering that the rate of certain kinds of technological advancement might be slowing just because humanity has picked away a lot of low-hanging fruit in the last century. Even though we don't know what 2040 will look like, a time traveler from 1980 would probably be able to understand it. 20th century examples of such gaps can be seen anywhere there was Second World central-planning style communism in place right next to First World liberal democracy. The most dramatic example might be East and West Berlin, where several neighborhoods destroyed by battle were left completely untouched 40 years since the end of World War II because nobody Eastern side thought they were worth rebuilding. Similar examples might also be Taiwan and China (at least until 1980, when China began implementing market reforms) or North and South Korea. Having some member states in your empire pursuing really bad economic policies that cause stagnation while others are not might be difficult to make sense if your Empire is like the EU, which is a project that is intended to integrate economies and other similar political entities together. The solution to that might be to simply not have your empire be about that, but about something else where they don't get involved in that sort of thing, for whatever reason. Maybe they just don't want to because messing around with that because the resulting disputes would cause the empire to fall apart, and they need the empire to stick together because there are jerks on the other continent who would try to invade or mess around with the member states if there was no empire. The external threat might smooth over any differences in values between members that might otherwise lead to conflict. Or maybe the conflicts between members aren't seen as being worth fighting over. 20th century communism was problematic because it was often coupled with aggressive and expansionist foreign policies, e.g. Soviets invading Czechoslovakia, Afghanistan and threatening to invade much of Europe, North Korea actually did invade South Korea, etc. It's not immediately obvious that as many people would care about the bad policies of these countries if there wasn't the constant threat of war present for decades. The obvious candidate for "something else" is mutual defense. Less obvious but still plausible candidates might be some aspect of culture or religion that is shared between all of the member states that isn't directly related to economics or individual freedom. [Answer] # Imbalance in Technical Education High technology can only be maintained if the people maintaining it have an adequate education level in STEM. The less-technical parts of The Empire can barely cope with making crude knockoffs of the tech made in the high-tech centers. The people in the low-tech areas who have enough money can buy technical items from the high-tech areas, but without competent maintenance personnel, they fall into disrepair. After a while, this becomes a mindset: It's just not worth it to give up the tried-and-true low-tech methods that our people have followed for generations, in exchange for toys that only work for a short time before they become worthless. The few people in the low-tech areas who do get good enough STEM education have a tendency to move to the high-tech areas, where they can be far better paid than if they stay home. One might ask why the imbalance in technical education exists. There are plenty of reasons that could happen. One is a social stigma against pursuing certain kinds of knowledge. Another is political. Anyone familiar with Lysenkoism knows how certain kinds of knowledge can be declared politically incorrect and therefore not pursued. Any time science reveals a truth that the powerful find inconvenient, they may act to suppress it. The high-tech areas have a strong tradition of free inquiry in science/technology research, and governments that don't try to dictate truth. [Answer] **Choice** The world advanced to the point that some people/countries decided for themselves to live in the 'better times' where that is whatever they defined. Want to live in technological wonder? *Tomorrowland*. Back in the 1800's? *Frontierland*. That gives you more possibilities for stories, up to and including when the people who don't know (their own history) anymore find a way down in to the (now fully automated) tunnels below the lands. [Answer] ### Natural EMP Most modern technology - transportation, communication, computers, factories, etc. - is based on electricity. Electric components, unless well shielded, are subject to destruction by an EMP - electromagnetic pulse. While EMPs are known to be caused by solar storms and nuclear explosions, there is some sort of anomaly in your planet which generates frequent EMPs in a limited geographic area. The land is fertile and has other natural resources, so it was populated similar to the rest of the planet prior to the advent of modern technology. But drive a car to the area and it stops working. Fly over it with a plane and you crash (well, hopefully glide to a landing). Bring in a cell phone and it's fried. Nobody has been able to figure out the cause. The people are the same - just as intelligent - and can use modern technology when they go to other areas, but they have to get there by horse & buggy. Since they have productive farms and mines, they participate in commerce. The kids grow up and go to university in the big city and don't want to go back. But plenty of others decide they want a slower lifestyle so there is a reasonable balance and the population is stable. [Answer] **Mutual Agreement** Lots of answers here, but one I haven't seen mentioned yet is the notion of two (or more) groups deciding to mutually avoid technological and cultural exchange. This doesn't have to be some externally enforced directive. It is perfectly reasonable that two societies, especially if they have massively different cultures, might want to limit their interactions to avoid social upheaval. If you want to see a great example of this, check out the *Foreigner* series by C.J. Cherryh. It involves a small population of starfaring human colonists stranded on a world of humanoids with a tech level similar to early 20th western nations. The influx of new tech and ideas from the humans end up destabilizing the local society and triggering a civil war. To avoid further bloodshed, both sides sign a treaty that limits contact between the humans and locals to give both groups time to adjust. It sounds like your setting is a bit different, but with a couple of key conditions you could make it work. * Initial Isolation. There has to be something that keeps your different groups separated long enough for naturally occurring variations to grow into a significant gap. * Population and Resource Differences. The lower tech population needs some factor that prevents their neighbors from just sweeping in and obliterating them. The best way to do that is to give them a sizeable advantage in population and natural resources. Sure the high tech society could win in the end, but the cost is going to be astronomical. * Enforcement. Similar to the first point, but you need to be able to enforce the treaty. It's not going to work if people can just mingle at will. You need ways of restricting travel and communication and both sides need to be committed to enforcing those limitations. [Answer] Lance2017 brought up electromagnetic hypersensitivity. It's obviously BS--but lets look a bit farther... Lets add something like a mosquito. It carries a dangerous disease but it's normal target is wildlife, it rarely bites humans. Unlike a mosquito it's bites go basically unnoticed. However, this critter is highly attracted to electric fields. You can get away with short term use of battery-powered devices without much risk, but once you start playing with generators and the like the bugs come swarming--and while humans are not their preferred prey they'll go after them if nothing else is around. Electrify, get bit, die. Those areas aren't going to electrify. [Answer] **Isolationism** Throughout history, there have been a lot of cases where countries...simply don't want to interact with any of their neighbors. You have cases like China prior to the Opium Wars, who barely interacted with the rest of the world beyond their immediate neighbors (Korea, Vietnam, the various steppe peoples) because virtually everything a civilization would need was within a short distance of them (the biggest attempt I remember hearing of China trying to secure more resources is when they sent expeditions to Bactria in search of better horses and south into Vietnam and what is today South China in search of spices and bananas. As a result despite the fact that China had paper and gunpowder it took several centuries before it really spread around. You also have cases like Japan, where the country intentionally isolated itself because the ruling powers didn't want things like firearms in the hands of the peasants, which led to the rest of the world bypassing them in terms of technology and Japan's eventual frantic catch-up in the Meiji Restoration when they realized they couldn't afford to stay isolated anymore. The obvious example of isolation in a fantasy setting you don't really get in would be your typical "isolated advanced elf village" people. Got enough of a headstart with technology they decided the rest of the world didn't interest them and turned isolationist. Don't really have to be imperialistic and use their technological advantage to conquer the continent because they are lucky enough to have all the resources they need within their territory. There's also the question as to whether you are talking about if The Empire is technologically unequal or The Empire is more or less advanced relative to its neighbors. Technological inequality within a country happens all the time. Typically the urbanized areas will have the most advanced technology whereas extremely remote areas will have little, at most the technology that does get there will be things that directly improve quality of life like vehicles, firearms, or medicine. Cheap, modern connections to the outside world to bring new technology in may be too cost-inefficient for the central or local government to produce (see: Alaska and northern Canada). There are lots of examples of this even today. The best example I can think of is Brazil, on the one hand you have cities with modern technology like Rio de Janeiro. On the other hand you have groups of people in western Amazonia that still haven't even been contacted by the outside world yet, or if they have haven't changed their lifestyle that much. [Answer] ### Imperialism and inequality Let's suppose the one advanced nation is an Empire, as you mention, and they have all the advanced technology. They are under no obligation to share their advanced technology with their neighbors. If they are like the Roman empire, they could conquer and enslave other nations, and it would be in their interests to keep the conquered nations as primitive as possible, lest they lost their technological superiority and the empire crumbles. Also technology is restricted to only the emperor and rich people. Only the royals have their own cars and planes. The peasants can only afford horse drawn wagons. The elites in this society keep all technology, education, wealth, and resources to themselves in order to prevent the masses from overthrowing them. You would have a highly regimented caste system, in which the upper castes live like modern day China and the poor peasants live like in the medieval times. ]
[Question] [ I’m working on a story-driven game, and I have an aspect of my game I need to create a lore-based explanation for. In this game humans are battling highly advanced robots. These robots are heavily armored, and pack powerful weapons, so ordinary troops haven’t been able to put up much of a resistance against them. But a special force of soldiers with hi-tech gear such as powered armor, energy shields, and more powerful and advanced weapons are able to combat them. The players control these special soldiers. So far, everything is explained neatly and tidily by my lore. But there’s one aspect of the game rules that I’m struggling to reconcile with the lore: players can’t be killed; they can only be essentially knocked out/incapacitated for a while. How can my players' armor protect them from being killed by these robots weapons? A previous idea I had considered that I’ve since rejected is that the players are controlling robots remotely, and this is how they can’t be killed, but, like I said, I think I’ve decided against this idea. I want the character (and/or player) to be there, in armor, not controlling a drone from some bunker somewhere. Let me lay some ground rules for qualifying answers: * There is no magic. This is sci-fi, though I have allowed for things in my story such as portals (traversable wormholes), which are theoretical. Not everything in my story must be exactly scientifically accurate, but it must be science fiction, things that are plausible and generally acceptable within the sci-fi genre. * Humans are not immortal. These soldiers can die, but their armor protects them against death from enemy weapons. * Their armor makes use of energy shields, which deplete every time they’re hit by the robot’s weapons. [Answer] ## You don't need to explain why Big [frame-challenge](https://worldbuilding.meta.stackexchange.com/questions/8008/when-and-how-to-challenge-the-back-story) incoming, as I'll be saying you don't need an in-world reason. But first, let me answer strictly your question before tackling the underlying issue: If you really do want to add in-world reasons, you only need to throw out some random explanations, and that'll work. I mean, if [morphine allows you to still run and shoot with broken legs](https://www.youtube.com/watch?v=6oPGjA5-4AM&t=280s), and you can revive bleeding out teammates just by giving them your hand1, almost anything will work just fine 😊. **This leads me to my frame-challenge: You don't need an in-world explanation for your game mechanic in the first place.** Throughout the existence of the gaming industry, game mechanics are most of the time akin to premises in worldbuilding: You set the rules, and people will gladly accept them as long as they're entertaining and consistent with the other rules. Then, if it's wanted, game-mechanics are explained in-world by just some techno, magicko- or bio-babble without going further onto it. And it works very well. How you implement how characters (cannot) die is especially one of the kind which is tolerated by the gaming community. To give you proof of that, see some of these game worlds below that pulled that off very well. I'm quoting examples from more story-driven games for the purpose of building a narrative-intensive game, but it happens virtually everywhere: * In most recent occidental RPGs with player parties, you don't die in game battles easily, if at all: [The Banner Saga](https://en.wikipedia.org/wiki/The_Banner_Saga), [KOTOR](https://en.wikipedia.org/wiki/Star_Wars:_Knights_of_the_Old_Republic), [Mass Effect](https://en.wikipedia.org/wiki/Mass_Effect)… No explanation is given for this. In fact, if and when to die is one of the settings you can alter in the [Pathfinder](https://pathfinderkingmaker.fandom.com/wiki/Difficulty_levels#Dead_companions_rise_after_combat) and [Pillars of Eternity](https://pillarsofeternity.fandom.com/wiki/Mode#Extra_options) video game series. No in-world explanation there, either! * Speaking of RPGs, somehow in Final Fantasy your characters never truly go down even after having been pierced by [10,000 giant cactus needles](https://finalfantasy.fandom.com/wiki/10000_Needles)… Until their dramatic cutscene comes in (e.g., [FF7](https://www.youtube.com/watch?v=BDhazVqxFs4)). * All recent [Elder Scrolls](https://en.wikipedia.org/wiki/The_Elder_Scrolls) and [Fallout](https://en.wikipedia.org/wiki/Fallout_(series)) have unkillable, essential characters, which is one of their famous trademarks. They will just need to take a breath, even after you fire at them with an atomic rocket launcher. Rarely, they die but [resurrect just to annoy you once more](https://www.youtube.com/watch?v=b46jhuYU2RQ). * Dripping into horror, the Resident Evil series has a good amount of antagonists who just don't feel like dying yet. Sometimes, the main characters make [snarky, almost meta comments](https://tvtropes.org/pmwiki/pmwiki.php/Main/WhyWontYouDie) about that. * All of [Telltale](https://en.wikipedia.org/wiki/Telltale_Games)-like games' deaths are scripted. Therefore, first, they're not really happening in actual game sequences like you ask1. Then, characters' lives are more tied to the story's needs than the world rules. They live just enough to set a [cliffhanger](https://tvtropes.org/pmwiki/pmwiki.php/Main/HisNameIs), for instance. ## Ok, it was left unexplained with success before, but is it a problem if I do it in my game? I'll end with a special game which will serve as the conclusion of my worldbuilding+game design advice. In [Celeste](https://en.wikipedia.org/wiki/Celeste_(video_game)), the principle of dying and coming back as if nothing happened is not explained at all from an in-world perspective, but it makes the most sense to showcase how Madeline—the protagonist—feels. This is a clear intent of the game designers, something you are told as soon as you change the difficulty3. They tell you they want you to die and fail with a purpose in mind: face the hardships the character is feeling and create one of the strongest bonds you can ever make in games. Explaining it would actively prevent transmitting this feeling: You'll just end up tripping over yourself and go in lengthy but uninteresting details rather than focusing on the game pillars and [unique selling point](https://en.wikipedia.org/wiki/Unique_selling_proposition). That's what makes an excellent, lively-relationship between your game and its world. **The most well-made games create game loops, character controls and game mechanics to further enhance the world and story they're depicting. It's so that players don't see the world, they feel part of it.** This means that sometimes you have to allow yourself to not explain game mechanics when it would muddle up (or worse, contradict) the themes and messages you want to explore with your story and world. From the description of your question, this seems exactly like one of the cases where you shouldn't be spending your and your players' time on that. So understand that most game rules are already-accepted premises you don't always need to explain through the world. Not everything in the world your player will experience need to be fully rationalized, and that's fine actually. **Good game worlds don't explain everything about what is happening in the game, because the world is *not* the game.** In fact, good worlds in general don't explain everything to the minute detail, be it for novels, comics or movies. The world shouldn't prevent you from keeping the player characters alive, nor is it always necessary to call for it if this your game-design decision. --- 1: The list of cooperative games doing this is sooo long. I'll just take a few from my basket: Borderlands, Left 4 Dead, Full Metal Furies, Aliens: Fireteam Elite, Helldivers... 2: I absolutely mean no offense to these adventure/point-and-click game mechanics, but QuickTime Events (QTEs) and single-click cutscenes pale in comparison to the battle system you're apparently designing. 3: As far as I remember, a pop-up appears when you get in the assisted mode to get more jumps or plain immortality. [Answer] **Emergency Teleportation** You say portals are allowable. These special armor suits have a built-in feature: they can teleport the user out of the suit and back to a predetermined destination in the event of an emergency. Perhaps the wearer can elect to do this at any time but this is likely frowned upon because the suit is the portal generator, and as such, does not make the trip. The typical use case is that when the on-board systems detect some unsurvivable condition (about to be hit with a tactical nuke, or the next round is definitely going to penetrate the armor, or the user is so banged up that they just need a hospital right now), the user is teleported "home" (likely to a prepared hospital room that is on 24/7 standby for exactly this case). So "death" is now more of an inconvenience. "Just before the missile hits, there's a flash of light and you find yourself standing in a hospital room." The inconvenience this causes the team can be entirely up to you. **The Paranoia Method** Or take a page from the old Paranoia RPG. Your characters *do* die, but they are clones. When one dies, the next clone is rolled out. You could have them keep or lose as much as you like in the process -- perhaps their very consciousness is transferred and they lose nothing. Or perhaps there are "nightly backups" and they revert to their last backup state (and skills gained since then are lost). Or whatever. The TV show Altered Carbon basically did this too (although in that show, you didn't necessarily need to go back to *your* body.) [Answer] For a slightly different style of answer: **Code of Ethics** For robots, destruction of one's physical form is probably a minor inconvenience. Just get a new robot body from the factory, download the latest copy of your core memories onto it, and you're good as new. Ready to rejoin the fight as if nothing has happened. As such, if the robots have a society with laws and/or expectations around ethical behavior, extreme acts of violence are probably okay. Perhaps celebrated for their comedic impact, even. But tampering with or destroying an entity's core memories, in whatever form that happens to take, would probably be some sort of ultimate taboo. It's just *not done*. And for humans, their core memories are an inseparable part of their physical forms. You can't destroy one but leave the other intact. If the robots understand this notion, intentionally killing a human in combat may be an idea so distasteful to them that they just won't do it. They'd incapacitate, but not kill. A comparable literary reference is found in the [First Formic War](https://en.wikipedia.org/wiki/Ender%27s_Game). Humans were attacked by an alien race with a hive-mind kind of setup, where only queens have sentience and independent agency and the workers/drones are just mindless, expendable shells. They initially assume that humans work the same way, with all the billions of people on the planet just being drones while the human queen is hidden away somewhere. Eventually they realize that every individual human is a "queen", and are appalled at themselves over the number of humans they slaughtered, because killing queens is *not done*. They're so ashamed of their own actions that they retreat back home and more-or-less allow the pursuing, angry humans to (nearly) xenocide their species. Similarly, Predators show some sense of ethics in that they won't engage an unarmed target with ranged weaponry and generally want their kills to be "sporting". A robot with a safely-backed-up consciousness could understand that there's no way for a human opponent to permanently kill it, and might therefore decline to permanently kill a human opponent. Because fair is fair. [Answer] It's not that they *can't* be killed, it's just not the robots' top priority. There might be a few reasons why the robots don't specifically try to kill the super soldiers. **It's easier to disable than destroy the gear.** Outright destruction might be too difficult or incur too much collateral damage. There may not be a real need to kill the person inside a suit of power armor if you can disable the suit itself with an EMP or something similar. If battles are fast-moving, robots may just leave disabled suits where they lay, since by the time they recover the fight will be over or have moved elsewhere. **Super soldiers are worth more intact.** Soldiers in this elite organization have intelligence the robots want to get their hands on. The armor and weapon technology may be more advanced than what the robots have, in which case the robots may try to capture technology intact rather than destroying it. [Answer] **Brain backups** Realistically, anything that's going to destroy your soldier's armored equipment and energy shields is also going to turn the human inside into a red pulp. It takes no more effort for the robot to kill the soldier than to kill the soldier's equipment. In fact, it's more plausible that the robot would kill the soldier by knocking the squishy human parts around inside the armor, but fail to destroy the armor itself. So if you want the soldier to be there in person but survive the experience, you can suppose that their experiences and memories are constantly being uploaded to a server room somewhere. When the soldier's body dies, these experiences are used to print a clone of the soldier and load them with the memories of the soldier. (Or try a more gruesome/dystopic route: home base isn't able to print a clone of the soldier, it just overwrites some random test subject's brain with the soldier's new memories, so that random test subject effectively becomes the soldier.) **Or psionic mumbo jumbo** I know you said no magic, but science fiction worlds often do have a loophole for stuff like telepathy. Perhaps the soldiers have learned how to telepathically transmit their whole consciousness to possess someone else's body when the soldier's previous body dies, taking over that body as their own and continuing their mission. [Answer] ## Ejector Seats Players get catapulted from the battlefield once they come close to death, immediately removing them from the battlefield. They can drop in a safe distance with a parachute afterwards and have time to recover. Some anti-gravitational emergency suit might mitigate the downsides of being turned into a living projectile. It overlaps with JamieB's answer, but I wanted to include this starker alternative. [Answer] ## titanium bathtub. The A-10 warthog was built with a heavily armored cockpit, and a lightly armored everything else. Making the whole thing heavily armored would make it immobile so you jut armor the part with a person in it. Disabling the vehicle is much easier than killing the pilot (now with a plane this often also kills the pilot but that's is because it is an aircraft). Powered armor should be designed in the same way, preferably with enough safety features to keep the pilot alive, things like crash pads or airbags or even crumple zones. the idea is you can super-armor the cockpit and rely on energy armor everywhere else because energy armor is more or less weightless. If you tried to make the whole thing as durable you make it to heavy to move. If the enemy really wanted too they could kill the pilot after the suit is disabled, but they would be wasting a lot of ordinance for little reason punching through the armor. They are out of combat either way. This could even help your game since your antagonist can threaten pilot cockpits (pods?) to get someone to surrender. But at the same time this could be a Geneva convention violation so a rare villainous thing. [Answer] **Robots have already won, they don't plan around humans** In your world, robots are the dominant species and mostly only care about other robots.They arm themselves to battle or police other robots and have weapons designed for that purpose. The good thing is that as a human, you don't have circuits and what would destroy or fry a robot will only stun or paralyse a human (with the appropriate gear). You could later introduce a special force of robots that have human oriented weapons that would kill, to add some pressure for the last stretch of the game. [Answer] # Disabling machines The soldiers can't move the suit on their own. When the shields are overwhelmed, the suit will redirect power from mobility to the shields. The soldier will fall over with suit and all, unable to move. They are protected by shields, but out of the fight. Robots will prioritise enemies that are a threat. This will mean they leave all soldiers alive until all are downed. After they might kill, or if that's better for your story capture them. Neutralising enemies is often the goal of combat. Killing is effective, but not efficient in many ways. Destroying supply lines, blinding people and more are all great ways to neutralise without killing in war. Robots will understand this better than humans, trying to neutralise enemies and not necessarily killing them. [Answer] **The combat suit is remote controlled** Even in modern military we are moving towards remote control drones both to preserve life and because it can be *cheaper* to deploy drones. Drones can be smaller if they don't have to fit a pilot and cheaper if you don't have to build in the infrastructure required to keep a pilot alive. In your future sci fi world drones may also offer advantages such as being able to travel through radiation or perform maneuvers with high G force that would kill a human. Thus it's only natural your future military doesn't put humans in the suits. Keep your highly trained elite pilots alive to pilot a drone another day! If you want to do that approach a few sci fi lore tid-bits you may want to include as well. **FTL comms?** Light speed puts a limit on the viability of current drones since being to far away limits the responsiveness of pilots who have to wait for telemetry to come in and their responses to be sent out. You may need some level of FTL to allow drones to be controlled from far enough away to be viable option in your world. Of course the pro of FTL comms is that you can pretty much make up how they work entirely. Perhaps there is a limit on how far they function that requires your fleet to be close to the drone and thus still be in danger? Maybe there are ways the enemy can interfere with them allow foes that mess with your UI or stun your drone? You can hand wave anything about how such comms work to suit the setup you want in the game. **Why not AI?** In reality such future weapons would likely be AI driven rather then human drive since AI can manage better responsiveness, better aim and reflexes etc. Easiest hand wave here is that you are fighting machines precisely because AI went wrong and the military is sticking to human drive machines so more rouge AI driven kill machines don't end up attacking them. [Here](https://worldbuilding.stackexchange.com/questions/17043/how-to-keep-humans-pilots-instead-of-ai-in-sci-fi-future) are plenty of other reasons for not using AI. **Why are drones humanoid?** *Assuming* the super suit you have designed still looks vaguely like a human you may want to explain why it looks that way if there is no human inside. The standard explanation for this is usually some variant of mind to machine interface. Your pilot interfaces with the machine in such a way that it feels like their body, they move it's weapons by moving their arms etc. To keep the mind to machine interface from getting too confusing your drone has to be vaguely human shaped so it will map to their brains idea of how a human body should work. IE humans are use to moving as humans so your drones have to be humanoid. **Keeping stakes high** The one down side to such a system is it can make the stakes seem kind of low. If humans are in no danger why do your characters care? Why haven't they sent out millions of these drones to destroy their enemies etc? To some degree Tortliena answer applies here, this is just standard gaming tropes and your gamers will be willing to accept it without difficulty. Still you can add a little stakes. 1. These drones are *Expensive*. Sure the pilot didn't die, but the lose of even one drone is a significant financial lose. The military can only build so many because of how advanced and difficult to make they are and they don't take the lose of them lightly. This puts some stakes since a lost of a drone still matters, and explains why there aren't hundreds of these things deployed. Maybe have some high level military guy chew your player out every time they die for loosing valuable military resources? 2. Feeling your body be destroyed isn't fun. Assuming you used a mind-machine interface you can use that as an excuse to explain why destruction of the machine their mind is currently inhabiting may not have positive effects on the pilot. Maybe pilots can still die from the mental trauma alone at times, and it just happens the player manages to escape each 'death' without this trauma. Still he doesn't know for sure the next death will be survived, and may risk suffering long term harm from deaths so he still has good motive to avoid it. [Answer] This is going to be a rather similar answer to @Tortliena - but from a slightly different perspective: In *any* form of Combat, random shit happens and people can die. Whether it's undiagnosed underlying conditions or plain ol' bad luck. Hell, people die when exercising or just living their life. The more you try and explain away your rule, the more you are going to have immersion issues. I mean, we can accept that someone who is wearing armor and shot with a .223 round can get knocked out. But when you have heavier weapons, it becomes increasingly hard to justify and make it consistent. Afterall, if a super soldier in *Power Armor* is merely knocked unconscious from a direct hit from an Anti-Tank gun/laser/missile/thing - then why is the tank destroyed, but not the super soldier? Why wouldn't they use that same level of protection for the Tank? Then my next thought was to do an Ethics type system - where the Robots don't like to Kill - but the problem there is again - randomness in Combat. Essentially: **If it's a Core game mechanic - simply state that it is. E.g. 'The combat suit keeps them alive, but will put them into a Coma for critical wounds' and leave it at that.** Any attempt to further justify or add realism into it, is opening Pandoras box of 'Whataboutism' For example - say that the Armor has an active protection system of nanobots that will detect incoming fatal levels of energy (laser/projectile etc.) and intercept it before it hits the soldier, but sometimes the energy dissapation knocks them out - then some smart-arse says 'but what if there were multiple shots at the same time by your killer robots and overwhelms the system hmmmm' [Answer] # The robots don't have a concept of a biological organism controlling a machine 1. The designers of the power armor know this, which is why they designed the power armor to be a great weapon against them. 2. The robots recognize two classes of threats; 1) other robots, and 2) biological organisms. The robots are very good at dealing with these threats and use weapons tailored to each situation. They assume wrongly that the power armor is only a robot and don't use weapons on it that would be lethal to humans. 3. The robots could kill the organisms inside if they only knew which weapon to use, and the suits are built to protect the humans inside (like in a secondary protective shell) from weapons that are mostly good against machines so that they aren't collateral damage. 4. Once the power armor is disabled the robots consider it dead and leave it/capture it/etc. and eventually the human can repair/reboot/or whatever it to come back (as this is the intent of the power armor). [Answer] The suits could be fashioned out of parts of robots, some rare and special models that are leaders (or sort of demigods) among the robots and worshipped by them. Humanity paid a hefty price to take these robots down, and since they are built in ways that human engineers can't yet fully reproduce, they were turned into suits for human soldiers – which conveniently explains their rarity. Robots are affronted by humans wearing the corpses of their former leaders, they are loath to combat them, but do so in order to disable and recover the suits. It would be sacrilege for the robots to further damage a suit once it's safely out of combat. They just have to recover it and store it somewhere, the human inside will die in a manner of weeks or months anyway, so they don't have to crack the thing open to kill the wearer. Of course this means that while humans survive, they would be captured. If only one goes down, it's no problem as the rest of the squad can recover him (and the robots won't finish that pilot off), but if the entire squad goes down, there must be some reason why the robots can't carry them off. Or, rescuing a bunch of captured pilots could be part of the game. If the religious/human angle to robots' behavior isn't desirable, it could instead also be some hard-coded rule. Command units have to be protected by all other robots at any cost and if downed, are to be recovered. All damage to them must be avoided. If humans steal a command unit, the unit is to be incapacitated and recovered, the unit is not to be damaged only to terminate the human inside, as it will die off quickly anyway. [Answer] In some old fantasy book, the main character went through terrible training where he died multiple times. But they somehow cloned him, so he could continue. [Answer] ## Super Soldiers Aren't Normal Humans Sure they may look a lot like people, but just as much work went into creating these unstoppable soldiers as did thier power armor. They have been genetically modified to have a wide range of super human abilities, not the least of which is being able to recover from gapping holes blown in through thier guts, regrow severed arms, etc. As for being able to die, perhaps there is something about how the robot weapons work that specifically triggers or aids thier regeneration. Cut thier arm off, and they bleed out just like anyone else, but those robots LOVE thier plasma weapons. But as devastating as these weapons are, they tend to cauterize wounds as they happen preventing the super soldiers from bleeding out. This cauterization leaves the soldiers stable enough for thier regeneration abilities to have time to work. [Answer] ## Plot Armor Your protagonists canonically *don't* die. That seems to go naturally with the plot right? If they died the story wouldn't be about them. Anthropic Principle says that this is the specific soldier that made it all the way through the war without a killing blow inflicted. Killing blows just never quite land. Their grandfather's wrist-watch in their breast-pocket deflects the fatal bullet. The shot missed everything vital and they could be patched up and get back in the fight after a little convalescence. That's not to say they have any supernatural ability to avoid death, this is simply the timeline where death never found them. In game-terms, if you die, you restart from an earlier save and try again until you get it right. If you finish a battle and you've "lost" some soldiers, they're not dead, they're just in recovery. They'll be fine in a few days/weeks/months. You don't need to explain it, though you might make a nod to the astonishing good fortune of your soldiers. If they used to be mercenaries, you could crack the joke that they're "Soldiers of Fortune" [Answer] Because the big bad robot controlling AI has a hard coded rule against killing descendants of it's programmers/humans with red hair/humans with technology above a certain level/... [Answer] **No threat? No need to harm them! Focus on the danger!** In a war, do soldiers destroy only military vehicles or all vehicles on enemy ground? - Only military vehicles, cause they may be used against them! If your soldiers gear is badly damaged, it either disables itself to go into a "harmless" state or can't fight anymore and is harmless. So: Why should robots shoot sheep when they can shoot wolves instead? Mice won't do any damage, wolves do! Focusing on the wolves is logical and needs to be done to win the fight. The sheep may be ignored while the dangerous wolves are still roaming. This enables multiple game mechanics: 1. You need to rescue your teammates. Leaving them behind is the same as killing them. If you can reach them, you can drag them to safety and "repair" them 2. Perhaps you can use some kind of stealth mechanics by hiding/dismounting your weapons or playing dead 3. You may pass robot barriers by walking by in disguise without weapons, which enables sneaky missions or assassinations 4. Your enemy robots may learn in later game that even downed/unweaponized soldiers are harmful soldiers and shoot them nonetheless. Higher difficulty! Also, robots may be tasked to kill humans, but your soldiers in their armors aren't humans, they're malfunctioning robots or just some unknown threat. Eliminating human threat is a normal thing in robot world, as well as ignoring anything unimportant that's not human and not shooting. Robots don't got infinite ammunitions as well. [Answer] ## Robots use EMP weapons for special forces Special forces are so heavily armored that they require electrical motors to move. Robots switch to electro-magnetical weapons (EMPs) to disable the special forces. The players fall to the ground, but are still protected by their heavy armor. There is not much more the robots can do about forces that use these extra tough armors than to temporarily disable them. Players are then rescued from the battlefield by support shuttles that lifts them away to safety. [Answer] ## Force Field Failure When the energy shields in the super soldier's suits absorb too much energy, they fail and "pulse" out an energy burst that just happens to knock out the wearer. It's really annoying, and the engineers have been trying to fix it / shield against it forever, but it's way better than getting shot, so everyone runs with it. Once they're down, they aren't a threat, so the robots ignore them. [Answer] ## Protecting against friendly fire Robots hate friendly fire. Your robots have designed their weapons so that they don't destroy their compatriots on the battle field. Their weapons are very effective against humans and their machines, but the most they can do to their fellow robots is shut them down for a while. Your special forces have power armor built from the scraps of an enemy robot. It is incredibly hard to kill those things, so this robot armor is rare. But because robots cannot kill other robots, they cannot kill your special forces. They can only cause them to power down for a while. If you're an exceptional robot hunter, you make a stockpile of scraps from your kills. You never know when a non-robot risk might damage your armor. ]
[Question] [ My setting is a fantasy where the average space-trekker subsides on scrapping derelict ships from a distant golden age in the past to maintain their own, with only the corporate rich being able to afford new construction nowadays. I may use some hand-waving for the setting since it is fantasy (e.g. space is a lot less empty than it ought to be), but I would like the denizens of the setting to plausibly and consistently play by the laws of this universe that's otherwise the same as ours. For the setting, I would like scrappers to have to work for their salvage (and specifically have to do a lot of repairing). Unfortunately, while some derelicts may be badly damaged by warfare and similarly catastrophic events, there are also derelicts that would otherwise be in great shape: * The former crew ran out of oxygen/sustenance and perished without any damage to the ship * The former crew had a falling out and killed each other with small arms, leaving only minor damage to the ship * Due to a loss of crew, the crew could no longer afford to maintain a few of their ships and had to abandon the fully functional ships on the way back to station * Pirates boarded and robbed the ship, killing the crew and taking their valuables, but left the rest of the ship in decent condition (e.g. don't have enough manpower to add the ship to their fleet, or it's just not worth their time when they are more efficient taking only the valuables) Is there any plausible explanation why even these derelicts might be in largely poor condition (but still partially salvageable with repairs) after say 1000 years? Note: I am trying to separate this from previous scrappers scrapping derelicts dry. This will certainly happen, but when you do come across something that hasn't been taken already, I'd like for it to be broken and not in mint condition. Chemicals: Chemicals like fuel / medical concoctions are easy to degrade due to chemical reactions (e.g. shelf life of hydrogen peroxide), but this gives me the opposite problem where it might be implausible to find usable fuel / medical supplies on *any* derelict (I'd like them to be rare. Not impossible) Electronics: Electronics use chemicals like in capacitors, so it's easy to justify their degradation like above, but again this might make it implausible for *any* 1000 year old electronics to work Inert objects: It's beyond me how some inert object like a metal chair would degrade in space over time to the point of requiring repair. In an Earth-like setting it's easy due to rust / overgrowth / etc, but none of that exists in space. And the more flexible the reason, the better. For instance, something that allows for 5% of some arbitrary electronics in a ship to survive is preferable to only a specific brand/model of electronics which avoids certain chemicals surviving. [Answer] Normal degradation outside of micro/meteoric impacts in most materials will be retarded in space. This applies mostly to those materials that exposed to vacuum and cold. However many components and systems within the whole of the ship may suffer from degradation over time anyway. We often hear about how conventional Wet Navy nuclear carriers can stay deployed for 20 years before refueling. however in reality they spend only about 1/3 of the time deployed. As much as it is in active maintenance. This of course is not a wartime situation. [![Carrie Maintenance cycles](https://i.stack.imgur.com/69Cew.jpg)](https://i.stack.imgur.com/69Cew.jpg) Many operations must take place to keep the craft from degrading. Much more for the far more complex space going vehicles in the OPs description. without replacing filters or consumables systems are affected. Ultimately all systems are connected and when one goes down, there is likely a consequence another is impacted. Liquids/powders/gasses for: * Lubricants * Coolants * Hydraulics * Propellants * Caustic cleaning agents * Munitions * Human Consumables * Waste Byproducts * Radioactives All are carried and stored aboard ship. Over time seals leak/break or degrade, sometime much faster if exposed to cold and vacuum when they are not meant to. Simple water freezing can cause explosive damage to structures if a container that was not meant to be frozen is. chemical can be corrosive even in dry forms to circuit boards and displays. Capacitors and batteries can leak. Some chemicals absolutely must be stored under specific conditions or cause "problems". So just the long term loss of power can be an issue. The space environment is not just cold and vacuum. UV damage to plastics, if used at large over the construction could be extensive. In the movie 2010 it was quite impressive they included the buildup of sulphur compounds on the hull of Odyssey from the volcanic eruptions on the Jovian moon Io. long term exposure to solar winds or cosmic rays could be death to any electronics absent active shielding. And unknown effects on plastics, organics and polymers. [Answer] 1000 years in space take a toll on anything: constant bombardment by space dust traveling at several km/s plus the particles contained in the stellar wind will deliver a noticeable cumulative damage, which is topped with the thermal excursion between illuminated and dark side. Electronic in particular is very sensitive to ion bombardment. 1000 years of it won't be kind on any electronic device. Moreover mobile metallic parts with unsufficient lubrication will end up being cold welded, which is rather incovenient if for example happens to a joint which is supposed to move. [Answer] ### Economics is the key The main reason any wreck that might be found hasn't been salvaged centuries ago is that no one could *afford* to do so. Some parts are more expensive than others -- engines and computers at the top of that ladder, hull plating and airtight doors lower, interior structure like wall and deck and overhead panels (lightweight but still strong enough to hold air pressure) along with wiring, plumbing, fixtures, etc. lower than those, and common stuff like furniture, fossilized foodstuffs, etc. aren't even worth hauling to the airlock. However, *getting to the wreck* is expensive, too. Someone had to front the value of the fuel, at least promise to pay a crew, do some minimum amount of maintenance on the salvage vessel -- in other words, what you get from a wreck isn't free if you figure in all the costs of "doing business." And a lot of what's left after a thousand years isn't worth the cost of getting to it. Salvage is an edge-of-bankruptcy job, much like wildcat oil drilling -- those who make a big strike can get seriously rich, but most of the drillers (or captains) are half a step ahead of the bill collectors, and wouldn't be that far if their equipment had more resale value. [Answer] ### Water damage Now hear me out: On these ships, the life support systems were left running. That means, among other things, that the air contains moisture which can degrade metals. But more than that: there have to be pipes throughout the ship carrying water. And a pipe breaking in all that time is not only possible, but even likely. Without a crew to fix this, you'll get flooding in any part of the ship you (as the author) like, and any resulting damage. You could even have a spill in a bio lab, or the pantry, which lets seeds germinate and grow, eventually throughout the ship. Imagine the salvage crew wading through a field of wheat... [Answer] ## Not their first rodeo Just because a ship is a) derelict and b) 1,000 years old doesn't mean it's been adrift for 1,000 years. Indeed, except when people go out of their way to hide them, shipwrecks in space aren't all that hard to find, and if you know where the big battles took place or where the shipping lanes were that pirates preyed on, you could snap up most of the wrecks much quicker than that. So people did, and because spaceships are valuable, the wrecks were refurbished and pressed into service. They were, as you imply, *mostly* salvageable - but mostly isn't 100%. Because of damage, exposure to varying environments, scarcity of replacement parts, or just the whims of their new owners, there were usually some bits somewhere that needed to be patched or jury-rigged. And when misfortune befell these salvaged ships, they were salvaged *again*, and again there were parts that needed to be replaced with something non-standard. Continue this process for centuries, until you've got spacelanes full of Ships of Theseus - allegedly, they're the same thousand-year-old vessels they always were, but repeated salvage and maintenance means that any given component might be a genuine centuries-old Golden Age relic, a cheap patch job hacked together a week ago, or anything in between. It's very rare that you find a complete, or even *mostly* complete Golden Age ship; it's the kind of thing grizzled old space prospectors tell stories about in dingy space bars, but few if any of them have ever actually seen one. So the answer to "why are these derelict ships broken-down, partially salvageable wrecks with only a few good components remaining" is - that's what they were like before they went derelict (the most recent time), too. Good-quality wrecks are rare because good-quality ships are rare. [Answer] A few things: 1. Space is *stunningly* hard on things. This has been mentioned before, but I think it's worth explaining in more detail. Space is so hard on things that part of what limits a mission's lifetime nowadays is how much space eats away at the materials. The shuttle even ran an experiment about it called the Long Duration Exposure Facility, whose purpose was to literally bolt materials onto a base and leave it out in space for years to see what happens. [Check it out](https://en.wikipedia.org/wiki/Long_Duration_Exposure_Facility). Space also makes things undergo tons of thermal shocks: orbiting from sunlight into shadow, or just generally having one side of the ship exposed to sunlight and the other not. This is why the apollo missions did a "Barbecue Roll", an approximately 1 revolution per hour roll to ensure that no one side of the spacecraft got too hot or too cold. 2. Let's say I got you a computer from even ten years ago. You're super pumped to get the data off of it but...wait...there's a password? If we're talking about the future, it is very plausible to believe that unbreakable passwords and access codes simply prevent access to certain components. Only the long-dead chief engineer could access the Chamber of Shocking Radioactivity in the engine room, and no amount of tinkering will get it open without killing you. This would be especially true of the weapons 3. The ships were designed so that, if they were abandoned for too long, their major components would melt into slag. Wouldn't want the enemy salvaging important stuff, now would we? [Answer] # The parts act like they're alive: This can either be literal of figurative. The parts are held in a complex conformation that needs constant power. Like a cell "dying," the programming and continuous operations of the part collapse once they are no longer kept alive. Once the crystal matrix/chemical configurations/whatever collapse, it's easier to make a new part than to get the old one to work. So they die and are now only good for recycling. But the parts don't need MUCH power, generally. A part with an internal battery can keep it self in a low-power setting for centuries. Parts connected to a resting but functional engine may stay alive indefinitely. So parts may die or not depending on damage, how much the batteries were drained before being abandoned, age, and if they are close to the engine or power conduits. Simple parts may even be able to "hibernate" indefinitely if shut down in the right way (which is rare if you're abandoning ship). [Answer] # Ships have self repair functions Ships have maintenance nanites and droids, which can perform basic repairs and fix minor issues. Over hundreds of years though, they degrade and fail. Many ships only have the nanites and droids left to repair a small number of objects. Ships failing often has destructive effects on other parts of the ship when random parts float around and smash into things, or volatile chemicals mix together and explode. This can cause damage to ships. Skilled scavengers know where the best salvage spots. The bridge, or the captain's room or engineering may have a higher nanite priority and have more lootable goods, depending on the ship model. [Answer] ## Because of creepy, aggressive alien critters You said that your world is more Scifi than hard science fiction. So it would be plausible that there is some form of HR Giger Style, non-sapient, aggressive, alien species which tends to nest in abandoned space ships. Their presence makes it very risky to board ships which were abandoned for too long. If you have a squad of well-equipped, trained and expendable space marines, and if you are looking for something very valuable, then you might risk an expedition. But any common space salvagers would need to be very brave or very stupid to board a space ship that was abandoned for longer than a couple month. The presence of the aliens could also damage the ship beyond use, so it might not be worth it to salvage a ship that was infested by aliens, even for one with the means to remove the infestation. [Answer] ### Not all ships wrecks are >1000 years old First of all, if you find a ship that has not been touched in 1000 years, it's going to be little more than scrap metal. Cold-welding and chemical degradation will ruin pretty much all of the technology on board. Other answers go into more details on that, so I won't. However, you are missing the fact that not all ships you find will actually be 1000 years old. > > ...with only the corporate rich being able to afford new construction nowadays... > > > You say it yourself that new ships are still being made; so, if you get lucky, you might come across a ship that is only 100 or even 10 years old. While these ships may be made in way smaller numbers compared to how many ships were manufactured 1000 years ago, they will still make up a surprising ratio of the derelicts by virtue of the fact that the 1000 year old ships have already mostly either been salvaged or fallen into a star or planet or drifted off into deep space where they are harder to find, etc. More over, if scraping and restoring ships is a viable occupation today, then it stands to reason, it's been a viable occupation for the entire past 1000 years. So, you may find a mostly functional hull of a ship design that has not been produced since the golden age, but that does not mean its been there for 1000 years. Maybe someone like yourself found it 200 years ago, restored it, and continued to use it until 50 years ago when it was lost to space again. So by combining these factors, it will still be possible to find a derelict ship, even a 1000 year old design, with some but not all intact systems even if having systems survive for 1000 years is not viable. ## Why most ships are worth scraping instead of restoring This is a simple matter of supply and demand. If your market becomes saturated with old broken down ships that barely function because so few people can buy new ships, then the value of a few choice scrap pieces may be greater than a whole used ship. The parts of ships that last the longest are worth no more than the metal they are made from, but things that fail more easily: computers, propulsion systems, power systems, etc. These will be worth a lot as salvage, if you can find any in working or near working order. Compare this to old cars. An old car may only be worth 300\$ at a junkyard, but if the transmission is still pretty new, and someone else needs that exact transmission to fix thier own car, they may actually end up paying 3000\$ for just the transmission because it is hard to find and it's in good condition. Even a refurbished transmission that did not work when you found it can be worth well over 300\$. So, because the sum of a derelict ship's parts are worth more than the whole, it makes since to only take what is worth the most and save the cargo space by leaving most of it behind. [Answer] ## Extreme biohazard risk A wreck in space is a surprisingly good place to accidentally produce a super-germ. Each of these space derelicts was inhabited by living people, and they brought their germs with them. They also brought heat and food and moisture. When they died, their germs did not. And unless the hull was ripped open, exposing the entire cabin to sterilizing radiation, those germs had the run of the place. Just as importantly, the wreck is a time-capsule that contains a collection of germs that were proven effective against humans when it was launched -- germs that contemporary society may no longer be equipped to defend against. Imagine if somebody in the real world dug up an ancient treasure chest filled with ancient coins *and smallpox* -- a disease we eradicated a while ago. Opening a wreck in space is like foraging for a snack in a college dorm refrigerator, and the rules are **exactly** the same: * avoid anything that's covered in fuzz * avoid any pools of liquid or weird stains * assume that anything is deadly whose container is not sealed air-tight * don't let your skin touch anything other than the one item you decide to retrieve * if something is sticky to the touch, drop it and go wash your hand with soap * when you exit the wreck, meticulously sterilize the exterior of your suit *before* you come into contact with your own vessel or other crew * enter your vessel only through the special biohazard airlock * spelunking suits are meant to be disposable: when a suit's lifetime "yuk exposure" reaches 7, discard the shell in space and then incinerate the inner lining as soon as you take it off The safest parts of a wreck are the parts that were cleanest and driest when the vessel was operational. Avoid the crew cabins, mess, latrines, showers, bridge, and rec rooms. Start with the exterior equipment, engineering spaces, and large internal machinery. Cargo bays are a real crap-shoot. Cargo values are obviously highly variable, but so are the hygiene rules of each crew: some ships treat the cargo bay like a high-security property room, others treat it like a shared multi-purpose space. So, some bays will be clean, others filthy. Every space is off-limits that contains a corpse or substantial amount of food or biomatter (or evidence of same). Yes, this does mean that if you're removing a fuel pump from the engine room and you discover an "empty" candy bar wrapper, everyone in the engine room must immediately (and calmly) set down/release any parts they are carrying, exit and seal the room, and call for a supervisor. Depending on the supervisor's assessment of the room, everybody who was in there needs to add some "yuk points" to the mental tally they keep for their suit. [Answer] **Heavy hulls** There was a brief period when energy was abundant and allowed to bring into orbit thick and heavy parts used to build the space stations external walls. Not only they were safer in case of impact by meteorites, but they shielded the occupants from the gamma ray. But the frantic energy consumption ended with a sudden collapse stopping all space operations, except for small satellites, for a long time, the stations were abandoned because resupplying them was too expensive. When space colonisation restarted they remained unused because they were in the wrong orbits to be useful and too big and expensive to repair and refit. The economy begins to improve when we get to the age of your story. The internal electronics and life support systems will degrade in time, but those thick hulls with heavy gamma rays shielding are still extremely valuable. The scavengers will have to check whether the welding on the outside have no cracks and rebuild the inside. Trouble is that the rigid walls withstand easily impacts by micrometeorites and meteorites up to a point, then they crack badly whether it will happen is just matter of chance. [Answer] Spaceships and space stations must, above all else, keep their insides *inside* and the outside *outside*. Suppose you find one in working condition floating around, uninhabited; it may be very valuable to you if you have a way of getting inside it without damaging it, but if you break *anything* on your way in then it'll be junk. And, being valuable things, the locks on them are pretty secure. A broken hull leaks, letting the vacuum of space in, and only the rich galactic elite have the resources to fix that sort of thing properly these days. But even if you find a spaceship with its hull intact, it won't be for long, because you need a tin-opener to get into it. [Answer] The question implies that wrecks that are available for salvage are mostly military construction and most often would be a part of old battle space. Question: what was the basic rules of space warfare? I mean: armies fight over objectives. Empty space has nothing to fight over... If this is the case of mostly intra-system combat (loosely speaking, of course), then the derelicts would be concentrated in star systems, probably more around habitable planets or, if whole system is not suitable for colonization, then strategically important locations (which should be much fewer). Following this option logically, it is quite possible that most of the wrecks will be either captured by space bodies' gravity fields, either in orbit or straight up pulled down to the surface. Then, depending on option they would more or less wrecked by conditions. Problem solved. If that would not be the case and you'd stick to deep space as main source of wrecks, then it is difficult to introduce extensive damage, indeed. But not impossible, because solar winds, all kinds of radiation and of course space dust will degrade anything over a millennium. Interplanetary dust is about 5 particles per cubic cm, interstellar is estimated to be much less, but still there, so that is a valid source of continuous damage. [Answer] A simple handwave explanation could be that it's very hard to find a ship in deep space, but much easier to find one that's orbiting around a planet or close to a sun so the ships that are found most often are effected by whatever is in that solar system. For example, a ship in orbit around a planet might be impacted by micrometeorites pulled in by the planet's gravity, or a ship in orbit close to a sun might be affected by radiation or gravitational shifts which slowly breaks down the structure of the ship causing metal fatigue. In real life UV radiation from the sun, as well as constant heat\cold cycles from going into Earth's shadow break down system on the ISS. So this is a perfectly plausible explanation grounded in real world science. Presumably the crew headed that solar system because they thought that they had a better chance of survival if they abandoned ship onto one of the nearby planets, or because the system was somewhere that potential rescuers could find. [Answer] **There are ships and there are Ships** Even in your golden age there were haves and there were have mores. Yes, there were ships with electronics which would fail in a few centuries, and would require continued attention from technicians to keep functioning. But there were also ships with precision and durable systems built to last for millennia. Yes, there were ships whose fuel could break down and become useless in time. But there were also ships with perfect sealed reactors which seem able to supply energy like magic, forever. Salvaging in a battlefield, you might find endless numbers of mass-produced fighters in various states. But how often will you find the fleet admiral's personal space-yacht, perfectly intact and waiting? How often will you find the experimental, fully automated AI-run cruiser which isn't a derelict at all, but would welcome the company of a few passengers after all these years? All of the ships of the golden age are wonders now, but only a few were ageless marvels, and how many of those are intact and yet lost? [Answer] ## The Ancient Alloys that were the primary construction materials of the majority of ancient ships are no longer well-understood. *Back in the day*, the ancients had access to some wonderous materials. They were cheap, easy to produce, and extremely durable... unfortunately, we either lost the knowledge of how to make them, or else the catalysts that made them so cheap or even possible are no longer available. Now, when ancient tech is discovered, it's anyone's guess as to whether the ancient alloy parts inside are still viable and, when they're not viable, there's no modern alternative to easily swap out. The tolerances on that wonder-alloy were incredible and, like all good engineers, the engineers of the past designed *exactly* to specification. To use modern materials, you'll have to do some re-engineering, and you might have to give up some features. After all, to replace the alloy firing pin with steel, you'll need to scrape out the targeting components to make room for the larger steel pin. Some smaller items--like those that weren't high-end or those that were crafted with traditional or cultural methods--were made more classically. Things like small arms, coffee makers, fancy chairs, etc, are all possibly cultural in origin and might not suffer this flaw. This has an added bonus effect that people might pay attention to the various cultural influences of your galaxy, since it would be well-known that *Traditional Kree'lin Boltcasters* are the most reliable hand-held weapons tech from the past that weren't based on the ancient alloys. Find one of *those* babies and it'll just need a spit-and-polish to fire straight. ]
[Question] [ In the galaxy I'm worldbuilding for my science-fantasy series, by far the most important planet in the galaxy is an ecumenopolis called Ishga. What I had in mind for this planet is something resembling Coruscant from Star Wars, with either the entirety or the vast majority of the planet covered in a thick urban sprawl with many different levels and sublevels stacked on top of each other, some so far down that they are only lit artificially. However, Ishga differs from Coruscant in that a narrow band around the equator is left uninhabited, essentially a giant wildlife refuge where the original native wildlife of the planet can flourish. Even with this change though, the sheer amount of ultra-high-density urban land on the planet would give it a population in the trillions, which for the purposes of my book series, I cannot allow (Ishga's population far exceeding even two billion would put it at such an advantage compared to the other worlds that there would be no real stakes in the galactic war my series is about). How do I have an ecumenopolis like this but still have a reasonable compared to the other worlds (2 billion or less) population? [Answer] Unchecked, the human population is likely to increase to the planet's ability to sustain it. So first let's look at reasons why it would be so small. **Option #1** A world of urban sprawl is presumably already mostly supplied by off-world colonies, so the limit would not be how much can be produced on Ishga but the supply logistics of bringing it in from off-world. There are only so many freight lanes to the garden colonies! **Option #2** Ishga is self-sufficient and has to produce all of its resources locally (i.e. no off-world supplies). If the planet is covered in buildings (and the nature preserve is well-policed) there's a limit to how much food and water will be available from rooftop gardens etc. So the population is naturally limited, though some government control may also be necessary to avoid regular famine. Which leads to.. **Option #3** The planet may have natural or artificial [population control](https://en.wikipedia.org/wiki/Human_population_planning#Reducing_population_growth) that means the birth rate does not exceed the death rate. This could be explained by the need to avoid civil wars, to avoid starvation, or all manner of social or religions reasons. Pick one! **Now you have to explain why the planet is covered in buildings** There are plenty of possible reasons for this too. Following Option #1, perhaps the entire planet is given over to ship manufacturing, or science labs, or exanet data centres, or whatever. Maybe half the continent is unpopulated, it's just some drone-filled Space Amazon warehouse. Per Option #2, perhaps that land wasn't useful for food production anyway - previous generations turned it into a desert or a polluted wasteland, or perhaps it just was never fertile in the first place. So you might as well build big. Per Option #3, maybe half the planet is covered in temples devoted to chastity? [Answer] ## Getting to the root of the problem: I am trying to follow why Ishga having a large population is a problem. You have already established that it is the most important planet for some reason. If it is the hub of manufacturing, it is disproportionate in a war. If they control trade, they are disproportionate in a war. If they have an invaluable strategic position, they are disproportionate in a war. People have nothing to do with it. Why wouldn't a large population be a disadvantage? Your city could be overburdened with intelligent life, and the stresses of it all make large portions of your world-city a burden. So rather than being at an advantage, Ishga is consumed with its own problems despite once being the great galactic police force to stabilize everything. Like a Great Britain completely dependent on its supply lines, Ishga has to constantly use all their strength to keep things open and unchanging. A single day of supply disruption means famine and civil war. The only situations where their population is an advantage are if: 1. voting by intelligent life forms influences the outcome of the wars (unlikely, but not impossible; have political parties divide the planet's votes to make them impotent), or 2. war is somehow dependent on personal abilities, like psychic powers, or the technology used in war is restricted by legal means and therefor population represents power (and again, like foreign fighters getting involved in Afghanistan, the Ishgans are so diverse that they divide their loyalties). The most likely solution to your problem would be that Ishga is a giant mass of factories and warehouses where the stored wealth of the galaxy sits amongst the palatial mansions of trillionaires (likely overlooking the nature preserve). Machines and robots do all the useful work, and thus you don't need a significant number of people on your planet. The problem with this is that realistically, this would make Ishga the **overwhelming** power in the galaxy in any war. Vast hordes of automated tanks, planes, fighters, and battleships pour forth from their massive factories. They dominate **everything**. Again, the number of people is small, but people don't represent power in the future. Your best hope is that such an Ishga has divided government. Each trillionaire is an island to his/her/its own family. Every planet is represented here, and any government is designed to maintain the status quo without interfering with the power and freedom of the citizens. Thus Ishga isn't really an independent planet, but more of a safe haven for wealth and the unrestricted source of all the weapons fueling the war. The planet sells weapons to both sides of every conflict and is really a non-issue in settling conflicts. You can certainly ADD a huge, seething mass of people to the planet if you want. The powers that be keep a vast mass of beings alive on the dole, sitting around and fighting amongst themselves or consumed with artistic (i.e. non-productive) pursuits. But there is no need for them. Make the population anything you want. They don't really matter. [Answer] ## Tiny Planet So, if you want a mega-city where the light never reaches the lowest levels, you need a population density that at least meets the highest population density of any city on Earth. Right now, that's Monacco with 26,000 people per sq km. If you need the population below 2 billion, then let's make a high estimate of 75,000 sq km of megacity (smaller than the US state of South Carolina). You want a band in the middle for wildlife, so let's assume that the Megacity only actually covers 50% of the surface of the planet. This leaves your planet with a surface area of 150,000 sq km, so it would need a radius of about 110 km. If the entire planet were made out of iron, the gravity on that planet would be roughly 1/50 the gravity of Earth. ## Frame Challenge: What About a Habitat? Instead of a planet, what if you instead made it an artificial habitat orbiting an otherwise uninhabitable planet or gas giant? A population of that size and density would fairly easily fit into a [McKendree cylinder](https://en.wikipedia.org/wiki/McKendree_cylinder) which is just a scaled up version of an [O'Neil cylinder](https://en.wikipedia.org/wiki/O%27Neill_cylinder). These sorts of cylinders create their own gravity by spinning and have to exist in pairs in order to maintain a steady orbit. Considering the hypothetical upper limit on size for a McKendree cylinder has 13 million km2, you could make a much smaller pair with more than enough room for 2 billion people and the agricultural area to support "wildlife." Depending on how old your stellar landscape is, you could even add a bit of history about the cylinders being built to escape some sort of planet-wide calamity (perhaps the result of an old war). That would allow you to make the artificial biomes in the cylinders unique to Ishga and representative of the species that used to be native to their planet. [Answer] ### The population is enormous. It's also uncontrollable. One solution to this problem is to say that the population really is enormous, but that with so many people packed into such a large area, it becomes unmanageable by the government to control that many. Most of the planet is controlled by various gangs with no interest in helping the war effort; instead, they spend their time and effort fighting each other, and if the government were to try to coerce them into helping, they might stop fighting each other and start fighting the government - a fight they would win, since they heavily outnumber available government forces. Of course, that also means that the planet would be just an uncontrollable by any polity that were to invade the planet - but if the government's forces get overthrown and replaced by a new government ruled by different people, the gangs wouldn't care as long as they were left alone to continue their business. [Answer] **The last war has left the planet a Mass Grave** A long time back, the galactic landscape was significantly more populous. Your ecumenopolis thrived with a teeming population of trillions. That is, until the *last* war. With supply-lines cut, the people starved, the planet was completely unable to sustain its population and most of them died. Entire areas of the city went dark. Without anywhere to bury the bodies (or people to safely handle them) buildings were sealed up with millions of corpses in them. Diseases ran rampant due to the profusion of dead bodies, killing billions more. Most of the planet is now a mass grave. The survivors have recovered for the most part, supply-lines are back, the city now grows a not-insubstantial amount of its food in bio-domes and there is a quiet attitude of "never again". Sometimes a building is unsealed and cleaned out for habitation, but nobody wants to disturb the dead more than necessary. [Answer] Build Ishga on a small moon, instead of a planet [Answer] ### Have the city built by other The occupants of the city are not the builders of the city. The city is and was being constructed by many autonomous builders. The planners and architects are long dead and gone(10K years+). No finish state was defined/reached for the builders so they keep building. They are old and mysterious enough nobody knows how to tell them to stop. The builders would be an outsized faction if they were not so single minded focused on construction and maintenance of the city. This allows for a much smaller population then the city suggests and with the population not controlling the builders they don't have outsized economic power. Which would mean an organization possibly gaining control of builders would be a plot point. [Answer] It sounds like you are following the path of Solaria in Asimov's The Naked Sun. I think you can achieve this in a similar way as in that series: * strict control on the reproductive behavior through education, to the point where intercourse is seen as a mere formality to be obliged as a social duty and physical interaction in general is frowned upon * large availability of robots for taking care of all the tasks, so that everybody can enjoy their isolated life. [Answer] # Necropolis Perhaps your planet is "most important" by being the spiritual center of the galaxy as well as whatever else it has going for it. Beings long to be buried there, and for whatever cultural reasons the majority prefer mausoleums to simple graves or being cremated or being crushed down to a synthetic diamond or what have you. At the extremes, you could have people buried in what amounts to exact replicas of towns or mansions or what have you. Or heck, you could even go crazy to the point of "the being's body was crushed into a synthetic diamond, placed in the forehead of a statue of said being, and being was placed in the "Human" sector of Ishga's Necropolis 7, which is an exact replica of Tokyo in 1995." Except that it sits a kilometer above the actual ground-surface of the planet, and 3 kilometers below where you can actually see the sky. Something like this would be the only way I can think of to cover a planet in a "city" yet keep the population at a somewhat steady 2 billion. The 2 billion population would be mostly those involved with maintaining/constructing mausoleums and people administering the planet/empire. If you want pilgrims that could give you a way to get added billions (or evacuate billions, or whatever). If you don't want pilgrims a simple "you must be the Chosen Caste or a corpse to set foot here" would solve most of that problem. Of course the OTHER way of getting a world-spanning planet with a paltry 2 billion population is to have some nanite "virus" or other artificial plague which took the planet down from the hundreds of billions in the past. But that seems like it'd lead to even more problems than my first idea. [Answer] A urban area is defined as an area with a population density of 193 people/km^2. If we go with the max population size of 2 billion people, as well as the minimum population density, then the planet's surface area would be $1.04\*10^7 km^2$. For comparison, Earth's surface area is $5.10\*10^8 km^2$, so that means that the planet's surface area is 2.03% of Earth's, and its radius is .143 Earth radii, so it would be a rather small world. Ishga would probably need an artificial magnetosphere in order to keep an breathable atmosphere. [Answer] It may not be possible. A lot of researchers have suggested that the human population right now is overshooting carrying capacity by quite a bitv(actual sustainable population over the long term may be anywhere from two to six billion), and ecumenopolises are heavily dependent on where they get their food from. You would have to have a significant amount of space dedicated to food and energy production if nothing else. By energy, I mean things like solar power, because a mass burning of fossil fuels would be both economically and environmentally unreasonable (you'd have to be burning several Earths worth of coal and oil to keep the planet heated, which would have to be imported from somewhere, and just think of the global warming and pollution from that) By food, it's been pointed out by many people that you would have to have local means of food production. Importing food from offworld would be hugely expensive and a logistical nightmare and would also make your capital planet incredibly vulnerable to attack in the event of a blockade. Society is three meals from collapse and all that. At the first major sign of war your equatorial wildlife refuge would be eaten just like how starving Parisians ate the Paris zoo in 1870 (or like how people in Venezuela are eating zoo animals now). Just for reference as well, two billion people is about the size of the human population pre-Industrial revolution, when there were very few large cities and most people lived on farms. [Answer] **The planet's main activity is some room-intensive (but not labour intensive) activity** I agree with the idea that you could ramp up the population of the planet without making it a powerhouse: too a high population is a liability under some circustance, since they must be fed and also the task of managing such a big infrastructure would be very challenging. Also, 2 bilions people would require a lot less room than an entire planet: even if I am very rich, I wouldn't need an entire block of skyscrapers just for me, it would be boring! Ultra wealthy people usually live in big estates, but usually the greatest amount of space is occupied by open-air structures, such as pools, sport fields, parks and gardens... So, the idea is that you need some economic activity that needs a lot of enclosed room, but very little manpower. A planet completely designated to that activity would be covered by a lot of such facilities (both for the finished produt and its supply chain), while requiring a "modest" population. For instance, they could build warp engines: These engines are huge and require some thousand square meters-sized clean room in order to build them (and also their components require a lot of space), while, thanks to the automatized manufacturing, only a handful of people are needed to manage the factories. There are hundreds of thousands of such factories on the planet, because for some reason it is the best place to build the engines (maybe because there is abundance of some unobtanium needed for them), and the demand for warp engines in a galaxy can be huge! This way the planet is almost completely covered in structures, even if the population is just a pair of bilions people (the people needed to operate the factories, plus all the people who must manage the society): the population can't go beyond some threshold, because there would be just a limited amount of living space on the whole planet, since the factories have the priority. [Answer] ## Plateau syndrome. Your planet's geology is a little different, and water is scarce. The plate tectonics create ocean trenches filled with sea water, but only the "sea bed" has enough air to be habitable. The "continents" are a tall plateau with only a few kPa of air. The "sea bed" is actually only a few percent of the planet, some of which has widely been set aside so that there is still some air to breathe next year. It has been very extensively developed, and due to this vertical landscape and concentration of humans in a small space (not to mention a lack of other employment), it became well suited for a centralized bureaucracy. ## Duels. There are over ten thousand slurs, epithets, taunts, fighting words, and politically incorrect abuses of language on the planet, each of which can be expatiated only by a Duel, fought to the death naturally. (What other way *is* there to say you're sorry??) The civilization used to be much more cosmopolitan and developed, but now the populace hides among the well-built towers of yesteryear ... trying to avoid notice. ## Cats. Your planet is the Capital of the Galaxy. The richest people from all the cosmos live there. And they build tall, tall climate-controlled towers staffed with the finest robots and security drones to tend to all of their beloved furry companions. Still, a person with only one mile-high skyscraper full of cats (and rookeries of birds for their entertainment) does not feel very distinguished. That sort of person isn't keeping up with the Joneses and his next promotion at the Bureau of Galactic Charity Regulation may be in doubt. [Answer] ## The buildings were built by robots that didn't care about population. If some terraforming process also made the buildings (and not the populous), it may have either miscalculated or not cared about the current population. This leaves you with either a rogue AI terraforming up buildings, or a disinterested population who are happy to live either side of the equatorial wild life refuge and not explore. Perhaps the disused buildings are non-sensicle in their construction, with buildings unfit for purpose. Or they've fallen so far into disrepair that no one wants to expand into the tropical wastes. It seems so rational to assume that the population would slowly spread out to fill the available space. But thinking-beings are anything but rational. [Answer] The fundamental problem is that if you want the **feel** of a multi layer city with huge population density, you need ... huge population density. If you want a population of under 2 billion, and the density is constant, this means the area must be small. If the area is small, and the area needs to cover the entire surface of the Ecumenopolis. Suppose you want 10 layers that are each as densely populated as Manhatten is: 25,000 people per square km. $\frac{2 billion}{10 \* 25,000 / km^2}$ is 8000 $km^2$. The formula for the surface area of a sphere is $4 \pi r^2$, giving us: $$8000 km^2 = 4 \pi r^2$$ giving us a radius of 25 km. This is 250x times smaller than Earth. This means its density has to be 16 times greater than Earth's, or 88 tonnes per cubic meter. The densest materials cap out in the 20s of specific gravity. You say you want a strip over the equator. We'll say that 3/4 of the surface is not city, either the strip, or open water, or something else. That raises your radius up to 50 km, so only 125x larger than Earth, and the density drops to 63. Regardless, the material this planet like thing has to be made out of is going to have to be extremely exotic. You can't even say "they built it around a fragment of neutron star", because all of the high density stellar remnants hold themselves together with their own gravitational pressure, which requires a surface gravity way higher than 1 gravity. Small amounts of exotic stellar material just explode and boil off, they aren't stable. On top of that, building a planet around a mote of white dwarf or neutron star exotic material doesn't work very well. Any kind of suspension will be unstable, and containment of that exotic matter is crazy. So instead, what if the city was built on an artifact of unknown origin. It was wrapped in raw materials (metals, etc) to a crazy depth. The original settlement, ages ago, mined those metals; over time, settlements arose. Eventually they dug down to the exotic core (which is near the size of the micro planet) and have exploited its strange properties to gain economic advantage. The copious resources on the planetoid and the unique technology allowed by using the exotic core as a catalyst led to a growing amount of urbanization, and eventually swallowing up much of the planet in city. While the surface gravity is near Earth levels, the shallow gravity well makes entering and exiting the gravity well much cheaper. Air pressure remains a serious problem, with huge reactors converting massive amounts of mined material into gasses covering much of the surface. Now, suppose we want a non-exotic material density. Iron has specific gravity of 8; or 11x less dense than the 25 km model. 11x less dense means 11x larger radius to get the same surface gravity (the math works out, really), so we need a radius of 275 km. This reduces population density by a factor of 121x, going from 10x Manhattan to 0.1x Manhattan. If there is a band around the equator that takes up 75% of the surface area of the planet, and half of the poles are ocean, we get back up to 0.8x Manhattan population density. If 95% of the industrialized surface is factory areas with a density of 50% of the City of Chicago, the remaining 10% has a density of 7x Manhattan. This "only" results in a population density of 1 per 6 m^2. If we have 20 layers on average and 50% transportation overhead (typical in real cities), each person has 240 m^2 to live and work in, or 2600 square feet. 20 layers on average in the "urban" parts of the planet isn't **bad**, and 2600 square feet to live and work is reasonably cramped. [Answer] ## Oxygen It is not feasible for your planet to import oxygen. Nor is it feasible for them to artificially produce it. (Technologically or economically would both work.) Consequently, though the planet has vast residential areas, it also has many vast areas of oxygen manufacture, also known as farms. This is important because the oxygen that is produced by a growing plant is consumed by the process of the plant rotting away. All food for the planet is grown on the planet. Furthermore trees grow in plantations that are also harvested for wood to prevent decay. When they start to outstrip the food/oxygen supply, witness inflation in food, the government starts shipping people off-planet. This is done in the context of the crushing burden of living on the planet for the poor. (If necessary, they add artificial inflation to induce emigration.) [Answer] Maybe property prices are just too high so few can afford to live there, and those that can afford to live there have a lot of stuff. A LOT OF STUFF. All dedicated to their own personal use. And all that stuff takes space and produces waste heat and at some point, you can't have any more waste heat because you can't remove it from the planet fast enough. What kind of stuff might a single person have that might take so much space and produce so much heat? Well, what if each ultra-wealthy person had several dozen power plants all dedicated for their own personal use? And farms and food processing facilities all dedicated to them and only them? And water filtration and sewage processing? And of course, refineries and factories to produce whatever goods they wanted from toiletries to furniture to computers to vehicles to starships? They would also need very own dedicated infrastructure to support such facilities and move around such facilities. And a private lake, of course. Or better, yet island? And of course, they would need their own personal space port and mass driver get my stuff in and out of orbit, because why would they share with anyone else? Sharing is for peasants. If all 2 billion people had these? That's a lot of space, and a lot of waste heat. The Earth has a surface area 510 million square kilometers. With 2 billion people, that leaves only a paltry 255 square kilometers per person use per level of the ecumenopolis. That's a 16km x 16km square. It doesn't even cover a quarter the area of a city. You couldn't fit all that stuff in there with just a single level for all 2 billion people. I think you would need a few levels at least, giving you a reason to have an ecumenopolis. The space port alone would probably take up an entire 16x16km layer, let alone all the stuff to support it. And of course, you can always use some aristocratic mumbo jumbo where they purposefully keep people off for no good reason on than their own whims. [Answer] # Demographics and/or economics ## Make the planet rich It's a problem that has already been solved by itself. That's because countries with the highest human development index (HDI) are the very countries with [sub-replacement fertility rates](https://en.wikipedia.org/wiki/Sub-replacement_fertility). In other words, well developed societies have a diminishing population. You will **have to** import new people continually or otherwise your planet will crumble. ## Make another thing more scarce If this is not very convincing, simply make the food really expensive. And it's easy in an ecumenopolis. Previous urban land was developed in the past, when food was cheap. All food needs to be imported then and now, where all is either de the city sprawl or raw wildlife. Food got expensive over the years, so now very few rich people can live comfortably here. [Answer] Most of the buildings are data centers and automated fabrication facilities. Perhaps the further you are from the green band the lower the population gets. [Answer] ## Manmade Ecological Disaster / Geomagnetic Reversal My immediate mental image upon seeing the question was Chernobyl, where a technological incident left a previously inhabitable area uninhabitable. Especially if it was fast, but not sudden (say a week or so warning), there could have been a mass exodus from the planet, with the remaining people being far away from the disaster. A related concern is Geomagnetic Reversal, where a planet's magnetic field flips, temporarily damaging it near the poles, bringing dangerous solar radiation to non-equatorial regions. While either could explain the exodus of people from the citadel world they built, you might consider combining the two. Geomagnetic Reversal takes hundreds of years, so perhaps they developed a massive device to bolster the magnetic field during the transition. If such a device were damaged, there would need to be a sudden evacuation of the polar regions before radiation became lethal. This would explain why buildings were left intact, why wildlife could flourish in the equator, and why a planet with infrastructure for the trillions would have so few people. Perhaps the last survivors are the uber-wealthy, who bought up the safe land in what's practically an archaeological site. Alternatively, perhaps only the poor live there, unable to afford a safe planet and forced to live in an irradiated tomb world? Maybe it's archaeologists/treasure hunters, ecologists who study and maintain the surviving wildlife, or mega-corporations whose use of automation means they can safely use the planet for construction. Maybe politicians live in a galactic capital city that should have been moved off-world years ago. There's lots of room for different reasons why someone would live in the shadow of such a massive world, and it leaves you open to tell your own story. ]
[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 6 years ago. [Improve this question](/posts/99097/edit) Imagine a country where once a year, the citizens file a sort of vote with their tax return, where each return decides how taxes will be spent. Each citizen controls an equal portion of the taxes, regardless of income. Taxes are allocated to programs. Anyone can establish a program by getting 0.5% of the citizen population to provide their signature endorsing the program. Programs are not allowed to violate any existing laws, and must publish an itemized report of where the tax money was spent. Each citizen who files taxes gets an equal say. They are allowed to split the vote between any number of programs with up to 0.1% precision. For example, suppose our country earns 1 billion dollars in tax revenue and has 1,000,000 citizens as population who file taxes. In this example, a program would require 5,000 votes to become established and each citizen would be responsible for determining the allocation of $1,000. Someone might choose to put 50% on a program to cure cancer, 20% on a program that repairs a highway they use regularly, 7.5% on a space exploration program, and the remaining 22.5% on a project to end homelessness by providing affordable housing for people. In that case, 500 dollars of the tax revenue would go to the cancer program, 200 dollars to the highway repair program, 75 dollars to space exploration, and 225 dollars to the homelessness project. Each year the projects would receive their budget based on the votes and the total taxes collected. Votes would be collected securely and projects would not be told who had voted for them. Now, I want you to come up with ways to break or game this system. Please assume the following: * The country has a democratically elected leader. * The country has free speech and nobody removes that right. This is in the modern age, so there is easy communication. * The country has functional laws preventing theft, murder, coercion, rape, dangerous drugs, etc... ie a standard functional legal system. * Programs do not ever find out who contributed to them. They only receive the total dollar amount. * The voting is properly counted. * There is a working secure way to verify the identity and authorization of the filing citizen. I want you to find the worst fraud or corruption that could happen under this system. I want to figure out how this proposed system could fail, in the worst way you can think of. In short, I want to figure out what negative outcomes could or should develop in this proposed country. [Answer] # Why pay for productivity, when you can pay for advertising? Your country has a space program. This program has a budged of 1 billion dollars, but wants a budget of 5 billion dollars to develop more awesome space stuff. The space agency decides to spend \$200 million dollars on advertising, and \$800 million on reasonably awesome space stuff. The advertising is a success! By spending \$200 million, they raised their budget the next year to \$1.5 billion! Drunk on success, the agency's leadership increases advertising again to $500 million! In the end, why even spend money on space stuff? Instead, we can make computer animated videos of space stuff and use those to raise money for your space program! # Who wants to pay for bad news? Your country has a center for disease control. This CDC is a responsibly run organization that doesn't waste its budget on advertising. Investigating a new threat, the CDC releases information on the mega-super-Zika virus which is incubating in the tropics to the south and could spread like wildfire next summer. The virus doesn't spread as planned. Everyone defunds the CDC, since mega-super-Zika isn't a problem. The next year, 150,000 people die of mega-super-Zika. # Sorry about those planes we ordered... Your country has an Air Force. It also has an enemy, the nation of Foot lead by evil dictator Oroku. The Air Force starts an ad campaign to buy a new fleet of F-5000 Awesomesocket jets, the most advanced stealth designed ever made, to defend against the vile Footers. The public responds, and the contract is signed for Aweseomesocket delivery in three years. The next year 150,000 people die of mega-super-Zika. The public, now more scared of viruses than Feet, defund the Air Force in order to fund the CDC. The Air Force can't make its yearly payment on the F-5000 program, and the company making them folds, having delivered no planes. Your nation is now a province of Foot. [Answer] **Lack of effective coordination**: Everybody loves curing cancer, everyone thinks it's important, so somebody decided to put all of their money towards curing cancer. Little do they know, all of their neighbors did the same thing. Society immediately begins to collapse as schools shut down and roads crumble, all while every penny of government revenue is shoveled into a cancer cure, even though there aren't nearly enough scientists to justify the expense. Huge sums are wasted as diminishing returns kick in. Fortunately, the next year everyone realizes their mistake and chooses not to put their money towards the cancer cure. Suddenly the funding spigot cuts off, millions of newly-recruited cancer researchers are now out of work and must retrain for new positions, abandoning the year of research they did. One way to correct for this is to have the total amounts of funding publicly available in real time. This way, people can see what programs are over/under funded, and change their allocations in real time before the election "cutoff". [Answer] I'm starting a new club. It's called the Gimmee club. We will have at least 5000 members and all of them will be taxpayers. We will be directing our taxes to a new program whereby cash money is distributed to the members of the Gimmee club. The money will be distributed to the Gimmee club members in proportion to the amount of taxes they paid. In this way, we will effectively be paying no tax. If other people choose to fund programs that benefit the nation as a whole, we'll get that benefit as well. Would you like to join? [Answer] You're basically asking how a capitalist market or referendum system can be abused. In short: advertising and marketing can be used to get people to spend money on projects which will not benefit them. Instead they will benefit someone else, probably the people doing the advertising and marketing. Just as advertising and marketing is used to get people to buy stuff they don't need. For the worst abuses, just look at the junk people buy today that they don't need or can't really afford. --- What you're proposing is very similar to a [referendum voting system](https://en.wikipedia.org/wiki/Referendum). Anyone who gets enough signatures on a proposal can get it on the ballot. People then vote on it directly. If it gets enough votes, it becomes law or even a constitutional amendment. [We do this here in Oregon](https://en.wikipedia.org/wiki/List_of_Oregon_ballot_measures). Usually it works out well, and the minimum signatures keeps a lot of crackpot measures off the ballot. But sometimes people are tricked into voting for something that doesn't have the effect they were promised. For example, [Measures 82](https://ballotpedia.org/Oregon_Privately-Owned_Casinos_Amendment,_Measure_82_(2012)) and [83](https://ballotpedia.org/Oregon_Multnomah_County_Casino_Initiative,_Measure_83_(2012)) were about allowing a private casino operated by a specific developer. People gathering signatures for the ballot measure would lead by saying "do you support Portland public schools?" Their logic was the casino would provide tax revenue, some of which would go to public schools. Nevermind that tax money would come from people gambling at the casinos. These were shot down by 70% of the voters, but you can imagine a situation where citizens are successfully duped into allocating their money to a project that simply lines the pockets of some business. [Answer] ### Open proposals > > Anyone can establish a program by getting 0.5% of the citizen population to provide their signature endorsing the program. > > > Find some group that makes up .5% of the population. Then they can 1. Direct funding to themselves. 2. Spend more money than they contribute. 3. Fund bad things. For example, neo-nazis make up .5% of the population in some countries. Perhaps the rules prevent concentration camps, but what else might they find to fund? I can foresee big posters at work. > > Expand the Mars program. They give us money! Vote all your budget to keep your job. > > > Perhaps some people will vote differently, but many will vote as the employer suggests. And large employers could vote in programs that subsidize themselves. I tend to think that we should shift budgeting power from politicians to individuals. But this doesn't limit responsibly. By allowing individuals not just to spend on approved programs but on whatever they choose, it shifts control of government power from the majority to a minority. My [similar suggestion](https://worldbuilding.stackexchange.com/a/29042/2113) was to allow people to budget the spending of their own taxes. Then someone can't just provide their entire income from the government spending they allocate because they can only allocate that portion of their income that they pay in taxes. Currently ownership and responsibility are separate. If I pay a lot in taxes, it just means that I lose the ability to spend that money. If I specified how the taxes were spent but within the government system, then I still spend the money. But I spend it within the societal options. I earn the money and spend the money. Society provides the options. Like the [cake cutting problem](https://en.wikipedia.org/wiki/Fair_cake-cutting) this balances two goals: majority rule without disenfranchising the minority. Allowing individuals to do both has the same problem as allowing people to cut their own cake. There's no incentive to limit the size of the piece that you select. Just grab the whole cake. When they run out, you can sell pieces to everyone else. ### Deals I offer to give you .1% of my budget if you vote for my .5% program. Sure, that's supposed to be private. But what if you let me look over your shoulder as you vote and I let you look over my shoulder as I vote? Hard to prevent. Note that without the .5% programs, that would be useless. There's no incentive to swap voting. It's easier to just vote for my own stuff. But with the .5%, it makes sense to spend a little to get support. ### Small programs How do I pass a small program? Say I want to spend just $100,000 on something. Do I now have to recruit .5% of the population to make one small expenditure? The .5% requirement is too low to promote responsibility and at the same time too large for some programs. [Answer] What is "the worst fraud or corruption that could happen under this system"? The electoral agency itself is corrupted. Yes, the votes are counted properly. But that's done in small batches compared to the whole. So whoever collates the votes publishes fraudulent results. Those parts of government that need funding the most could offer bribes. Also, there will be government institutions and instrumentalities that have the capacity to influence staff in the electoral agency will benefit most. For example, the military and intelligence agencies will be able to bring the maximum pressure to bear to ensure they get the funding they need and want. Corruption at the heart of the system itself will do the utmost to pervert this democratic taxation system. [Answer] Thrashing would be a big issue especially in any areas with long lead times. This refers to a system that repeatedly flip-flops from one state to another. If the people voted for one set of priorities one year, but the next year changed them drastically due to changing circumstances, political scandal, bad publicity or exceptional marketing it would cause chaos. One year the officials at NASA have loads of money and plan their big rocket, whilst the army is laying off soldiers left right and centre due to lack of funds. The next year NASA has no money so has to cancel the big rocket program they had already started, whilst the much diminished army has loads of money but no trained soldiers. [Answer] You may want to take a look at switzerland. The referendum is a very common thing there. As are the faults of that system. We all know that democracy is the worst system, except all others, which was meant to point out that democracy by itself is not a very good idea, you also need checks and balances and at least a group of fairly alert people with the will and the ability to counteract imbalances. Your system will fail almost immediately, because people can vote on their spending, but are not held responsible for the consequences. Should we build this new nuclear power plant? no. Should we build this hydroelectric dam that is going to flood a wildlife preserve? no. Should be wuild windmills, coal or gas plants? no. Do you all want to live in the cold and dark? no. Okay. Where is the energy going to come from? yes. Hm. Yes is not a useful answer here. But your system only allows for yes and no, and it is dearly missing any means of enforcing that the consequences of a decision be known and taken care of. Or, in other words: Your system can only work as lnog as an overwhelming majority of voters is well-informed and has the best intentions. Which is just a synonym for **it cannot work.** [Answer] Every answer so far points out one or more flaws. One more that affects all of them: consider how USA has “free speech” but that doesn’t stop politicians and journalists on both sides from lying. ]
[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/251504/edit). Closed last month. [Improve this question](/posts/251504/edit) Suppose that during the height of the Cold War, nuclear war unknowingly breaks out. Seemingly "on accident", by the actions of a certain group of individuals, the nuclear missiles get launched by both sides, without the agreement of the political authorities. The nuclear missiles are launched by some individuals or a group of conspirators who are not aligned with the rulers of the countries. The rulers of the countries did not want the nuclear war to start. It happened without their knowledge or approval. But what was done was done. Several cities were destroyed, and fallout covered a significant amount of territory. But no any other military actions were taken. But the governments of these two countries have a kind of 1984 agreement with each other. They are secretly in cahoots, only making an appearance of a Cold War, and somewhere along the line someone accidentally started a nuclear war in reality. Now that the damage has been done, the corrupt rulers are quickly scrambling to control the damage, preserve the status quo, and prevent the general public from even knowing that a nuclear war ever took place. They want to cover it up, to make sure that the general public would be uninformed of whatever happened. They want to preserve the status quo, that the fake "Cold War" is still going on, and nothing has happened. Both of these governments are secretly working together to keep the knowledge of nuclear war from spreading. And they can use any methods to preserve the status quo. They could simply kill witnesses, kill or intimidate people who are speaking the truth, controlling the media with an iron fist, and restricting the movement of people in the country. But what would they do about the cities that got destroyed, or about the fallout over the large territories? What are some actions that they could conceivably try to cover up the nuclear war, either by claiming that aliens did it, or something else? [Answer] # Solve the right problem What you are trying to hide is not the fact that there was a nuclear exchange... *"I am sorry, a what now?"* An exchange of nuclear weapons. They did not have a *war* because a war requires a *declaration of war*. And the fact that hostilities took place does not necessitate a declaration of war, nor does it necessitate Mutually Assured Destruction. So your faux-adversaries do not need to hide the fact that nuclear weapons were flung at each other, a task which is practically impossible anyway because such things *will* be noticed. What they do need to explain is why they did not step up to full-blown war and world wide annihilation. Exactly what explanations are viable depends entirely on the rest of the world politics. Especially this: what did the two nations publically state before the atomic cow pat hit the fan? How did they say they would react? But in the end I think they will mutually agree to... ## Lay it on thick with the misinformation The best way to cover up a lie to drown it in lots of truths and half-truths. So these nations will agree to muddy the waters as much as they can regarding who shot first. And both will claim the moral high-ground saying that they showed admirable restraint in the face of this unprovoked attack. ...and then it will be business as usual, the Cold War goes on after this little heat-wave, now with ample justificatin to show that the other side cannot be trusted and are in fact evil buggers that will even take to tossing nukes about. ## In summary Solve the right problem. Hiding nuclear destruction is a hard, nigh impossible problem to solve. Covering up a conspicuous lack of animosity after this exchange, on the other hand, is — still not easy — but a far more accomplishable task, at least compared to covering up city-sized piles of radioactive glass and ash. Using the hostilities as a propaganda tool to justify continued Cold War turns this unexpected kerfuffle into a useful asset. All that is needed is that the propaganda ministries of the respective countries go into overdrive and use their rumour mills to churn out deliberately conflicting stories about the exact timeline of the event. [Answer] Just find a scapegoat. There's always some group either domestic or foreign that can be labelled as dangerous nutcases and given the blame. Then apologise for the intelligence shortcomings which failed to stop the imaginary group. Be excused by the public since you're owning up to the failing and promising to do better while looking heroic. Then shift public focus somewhere else by invading the middle east or playing wargames in the Ukraine or something. If all else fails fly some planes into a building and then invade a couple of countries in retaliation live on TV and make it like a video game. It's a great business opportunity for everyone from arms dealers to caterers. A few million people died, but as Stalin said 'One death is a tragedy, a million deaths is just a statistic'. [Answer] "It was terrorists who dun it!" The destruction of cities by nuclear fire is just too big a calamity to sweep entirely under the carpet of lies and disinformation. Therefore, the best way forward is not to deny the event, but to shift the blame. The event may have been caused by people following orders to launch missiles in the event of an attack, it may have been caused by people exceeding their orders, or it may have been started by a third party. Whatever the cause, as long as information about *that* can be controlled, the situation can be controlled. So, this cabal controlling the two supposedly 'hostile nations in their cold war' would merely have to come up with a plausible story or two to explain how missiles were launched... preferably two *conflicting* stories. Country A goes with Story A, Country B goes with the *conflicting* Story B, and as long as neither story is a *cassus belli* in itself, the disagreement over the cause can be a reason for the two nations to continue to 'distrust' one-another rather than uniting over being mutually manipulated by some third party. That way, each government would also have the excuse of 'rooting out traitors/infiltrators/spies' to institute more repressive or intrusive initiatives, *with* the public's support. [Answer] I think other answers are greatly over-estimating the amount of information that people can get in a society with "1984" level control. In our world, this would be nearly impossible to hide. But we're not talking about our world. Without any free press or freedom of travel, anyone living and working more than about 200 miles from one of the explosions (i.e. in virtually any city not directly hit) would never know it happened. The people in the suburbs would get a story about an industrial accident and would have no reason to go digging further unless they are protagonist troublemakers. That story might even make regional news if the government felt such a report would be useful. This would explain damaged infrastructure to anyone who didn't look too closely. And nuclear fallout? Who cares? The next generation is going to have more cancer cases than normal. The puppet masters can plan for that in their population projections, but beyond that it's just not a problem. The people who were close enough to see the blast but far enough to survive will have to be handled in whatever way people are normally handled when they see something they're not supposed to. Disappearing permanently? Re-education camps? Whatever the world already allows for. This might be an unprecedented new scale, but it won't be the first time that sort of thing happened. And what about people with relationships? Your aunt from the next city over suddenly stops returning calls? Well, it's unfortunate, but people get reassigned suddenly sometimes. Secondary characters have survived in this world long enough to know that you don't ask why unless you want to be suddenly reassigned yourself. So TL;DR? In a "1984" style setting, this is more of an annoyance than a problem. Just keep doing what you're already doing (until the annoying protagonists make use of that information in some way). [Answer] I think most of the answerers here are overthinking this. The obvious solution is: # A massive disinformation and propaganda campaign Since you mentioned 1984 I'm assuming both of these countries have great control over the mass media within their respective territories. So, just downplay the fallout by reporting it as other things: * Communication lost with family and friends in one of the destroyed cities? Oh unfortunately there was a natural disaster (tornado or whatever) - your family member must have been one of those affected. So sorry for your loss. * Rivers were poisoned by the nuclear waste? No, there was just a leakage detected at a nuclear testing facility, several people became ill and died but it is being contained. * Food shortage due to destruction of crop lands? There was a famine this year due to low rain or oddly long winter, don't worry it will recover by next year. Then just restrict communication with people from different regions so nobody knows the full story and can't connect the dots between these seemingly unrelated incidents. The only issue is the physical damage - it's hard to deny what you can see with your own eyes, so just limit the exposure as much as possible. You can easily restrict travel by saying there is some kind of virus outbreak so people need to be isolated in their own cities. That just leaves the people who live nearby; they will probably need to be "re-educated" and threatened not to tell anyone. [Answer] ## It's not a war, it was just a technical glitch of the launch system Instead of trying to hide the fact that nuclear explosions happened (hard), try to hide why they happened. It would still be difficult to hide where the explosions came from *physically* (it's obviously not just a nuclear power plant, lol), but you can just play it off as a software or electrical error. > > The internal "don't launch nukes" capacitor finally burnt out. > > > If people dig in further, you can shift the story to it being a UI issue. > > Our mistake, turns out that capacitor never existed! Technical details are very hard to get straight, unfortunately. Actually, the system forgot to ask Crazy Tim for confirmation of the Nuke launch. Tim assumed it would because it's an irreversible operation. So it was actually caused by a poor UI decision when you think about it. > > > [Answer] It's super important to note that no matter who did it, nuclear war is nuclear war and has non-zero consequences. Because of that, it is in the government's best interest to not only create a third party to attack, but to accurately target and remove dissidents or terrorists within the country that would possibly cause a "true" major powers nuclear war. Therefore, whatever solution they come up with, needs to be dosed with McCarthyism, to have the public opinion strongly turned against anyone who would cause such a fallout in the future. The solution I'd suggest is for both sides to explain it as a rebel or terrorist faction aligned with the second power within the country, but one without official ties to the other government. We see this situation already playing out IRL with the Houthis in Yemen, where they get blamed for firing missiles at American warships, when in reality they're a group controlled and funded by the Iranian government. The American government doesn't want to start a war with Iran and potentially Russia / China, so it's much easier to blame the rebel faction or group. A similar solution would probably work in your story as well. [Answer] You didn't really indicate the genre and wider circumstances leaving an opening for me to offer: The crack/parody/comedy option. For example to go with the given option you could have the government say that aliens did it, but have the joke lie in how absurdly gullible you portray the citizens as. Maybe have one random 'crazy' conspiracy theorist proclaiming the truth and being brushed off while inadvertently acting as the straight man to the reader, but basically all the rest of the people buy the lie hook line and sinker which causes other problems as people go crazy from fear. Everybody who can is building a nuclear shelter, causing all sorts of shortages and tons of stress for construction workers and DYI shop clerks. Have it be like covid for us, but instead of masks everybody is required to wear a tin foil hat. And then have the epic climax be that aliens actually did come to attack the earth but were scared off by the nuclear bombs and the general insanity but the presence of one of their rookies captured on film is enough to prove the government's lies. If this is a parody and the comedy level is one of extreme exaggeration for everything and or for children, then no one actually cares about the bomb especially when the two governments just "come out" about being in a friendship publicly and then host a huge party to prove how not-enemies they are and then if anyone objects they could get rid of them maybe making a spectacle of the rebel Hunger Games style. If you are not going the humor route I can see a few semi serious options: If the world this takes place in is partially fantasy, anywhere from steam punk to being towards the end of a magitech industrialization, and or the supernatural is known to be an actual factor. The government could say it was caused by a space cryptid/demon/god/a bad luck curse, and have it be believable and maybe even actually true. If the civilization is dystopian the government might actually have 100% control over everything already. Like they run all the news agencies and everything/as in basically every kind of media public or not is just at least 99% propaganda. Also people are indoctrinated and brain washed from a very early age and maybe mind control and or memory manipulation of the masses is a thing and they disappear anyone that is immune (I am thinking a later plotline is that the fall out from the nuclear radiation in addition to the usual horrible side effects it also in low levels like on the out skirts makes some/many people immune to the brain washing/mind control potentially causing trouble later). So basically they just have to tell people that there always was a nuclear wasteland over there what are you talking about? Things are the same as they always have been and everything is fine and dandy and under control take this nice happy pill and get back to work. Basically gaslight everyone but succeed. Reminds me of of what I have seen of that one game 'We Happy Few' . [Answer] That really depends on what they actually need to cover up. The fact that cold war supposedly turned hot? The fact that nuclear strikes happened? The fact that a few cities got destroyed? First I'd like to point out that the fallout from nuclear weapons is greatly exaggerated, referring to [real world example](https://en.wikipedia.org/wiki/Atomic_bombings_of_Hiroshima_and_Nagasaki#Post-attack_casualties), so people could settle back to those cities almost immediately after the fact, but something would have to be done with survivors. So to answer the first question - the easy thing to blame would be on industrial accident(s). Since, I presume, the strikes happened relatively at the same time, some more work would have to be put into making it look plausible, but it can be done. Does this era have computers? Things can be blamed on computer viruses or cyber terrorism, say that terrorists hacked into some factory producing something explosive and/or dangerous and caused this explosion. Some real world explosions can be compared with smaller nukes, but as long as the population is enough unaware and ignorant this lie can be fed to them. They don't have computers? Well you can try to scapegoat some chemical companies, say they got infested with rogue actors that caused industrial sabotage on a massive scale. To answer the second question - assume the war with the other nation has gone hot, but no nukes have been used. Blame conventional high-yield weapons. Claim the enemy has struck something like a gunpowder factory or a weapons storage. Blame destroyed cities on firebombing by enemy aircraft, which create a hellscape no less terrifying than nuclear weapons. Also, as a bonus, you can go for unconventional route - [conspiracy theories](https://apnews.com/article/fact-check-nukes-fake-camera-conspiracy-rogan-742805510402). That would be a great and evil way to do it. After all, if the public can find the best ways to prove something is real that isn't, why not let them find the answer to the question they seek and embrace it? Wall off the cities, don't tell anyone anything and say that cities are under "quarantine" until the investigation is finished. Which investigation? Let the public decide. Look to the most interesting theory (besides those cities getting nuclear blasted) and embrace it. Maybe public will think there is a dangerous contagion there? Or they make a theory that there is an ongoing fighting in the cities already. Or that there is terrorist activity. Or they are taking people from those cities somewhere (maybe drafting to war?). And then just tell the news outlets to embrace it, put it in print and at some point say that the "investigation" has concluded that public was right this time! [Answer] ## Create A *Different* Nuclear Disaster Just tell everyone that a [Chernobyl](https://en.wikipedia.org/wiki/Chernobyl_disaster) or a [Fukushima](https://en.wikipedia.org/wiki/Fukushima_nuclear_accident) happened. It gives you a great excuse for having a bunch of dead people and for creating a radioactive exclusion zone. You'll have to [gaslight](https://en.wikipedia.org/wiki/Gaslighting) or disappear anyone who claims to have seen a mushroom cloud or missile, but that shouldn't be hard for a sufficiently authoritarian government. For Bonus Points you can blame the accident on whatever political enemies you'd like -- "the opposition party forced us to cut funding and look what happened," or "the people demanding free elections finally showed their true colors with a terrorist attack." [Answer] They were closing in on a cult. The cult leaders at least chose suicide over capture. We have enough real-world examples of cults doing this that it's not that unreasonable--it's just they usually don't go out with a thermonuclear bang. And note the effect--it was a coordinated simultaneous raid (enemies can cooperate on dealing with external threats) on their entire leadership. Thus there isn't anybody left to go after. Missile fields are usually in very remote places (deliberately, to isolate the fallout when they're attacked), in a 1984 world there very well might not be civilians permitted close enough to even see the birds. And if the incident involved boomers there's even less to see. Such cultists are usually too inept to build nuclear weapons (we've seen them try--and not even get to first base. They managed to make Sarin but not an adequate dispersement device and only killed IIRC 7.) However, that doesn't mean they couldn't have recruited someone who did know. Pick a few scapegoats that actually died in ways that could have been murder (was it really an accident he hit that elk or did someone stage it?) and blame them. (For those of you who don't know elk--they are big enough a collision at highway speed can easily be fatal and like most wildlife they have no respect for the danger of being in a highway at night. There aren't nearly as many of them as there are deer so they don't cause as many accidents, but it's much worse for the occupants of the car to hit an elk.) [Answer] In his novel *Fall; or, Dodge in Hell*, Neil Stephenson takes a jab at the conspiracy scene. Somebody orchestrates the hoax that the city of Moab, Utah has been destroyed by a nuclear bomb, with paid actors as witnesses and fake videos which set in motion an avalanche of fake news about the alleged incident which takes on a life of its own and is impossible to eradicate, despite of all the evidence to the contrary provided by reality: I mean, you can actually go there and see it. If you are willing to escalate that idea you can take it a step further and turn it inside out: The government and all the state controlled media (see the [Twitter files](https://en.wikipedia.org/wiki/Twitter_Files), escalated just one step) declare reports of the attacks a hoax. Anybody promoting it is labeled a conspiracy theorist. Posts by them are silently suppressed, the "established" media are controlled, for all intents and purposes everything is normal. [Answer] "Yes, hello, Dmitri. Listen, I think we need to talk... ... No, **WE** didn't launch any missiles! We sort of thought maybe ... You didn't either? Well, that's really a shame. A lot of our cities are burning, Dmitri, and I'm afraid ... yes, I know, Dmitri, but you don't have to worry about winning an election every four years! I mean, this is the kind of thing that's hard to explain to the voters! ... OK, sure, you've got the Politburo to worry about, but maybe they've all been incinerated? ... Well, who knows - maybe you got lucky. ... Yes, of course, it's not really something to joke about, but I thought it might lighten the mood. ... Well anyways, Dmitri, while I've got you on the line, there was something I wanted to ask. ... Sure. Anyways, since a lot of **our** cities have already been destroyed, and a lot of **your** cities have already been destroyed, why don't we just kind of, you know, finish the job? I mean, *we* could launch **our** remaining missiles at ***our*** undamaged cities, and *you* could launch **your** remaining missiles at ***your*** undamaged cities, and then, you see, we could just kind of sweep the whole thing under the rug. ... Yes, I think - General, do we have enough missiles left to wipe out our undamaged cities? Thank you. Yes, Dmitri, the general assures me we have enough missiles left to handle that. ... What? Well, sure, you could use bombers if that's what you've got left. I mean, we might have to do the same thing! ... Oh, sure - always nice to talk to you! Say hello to Mrs. Dmitri, and maybe we can get together for one of those nice conferences in a few decades, once the radiation has gone down. Bye-bye, Dmitri! Arrivederci!" [Answer] Have you ever seen a nuclear detonation up close? Me neither. All I've ever seen are Youtube videos. In real life, after the blast most people who witness it will either be dead or dying soon. Everyone else will only see the destruction. Just say the damage was caused a meteor that broke into pieces before hitting the Earth. We usually only see dino-killing asteroids **AFTER** they've gone past us. And though we always say the chances of one hitting us are very low, they are never zero. The fact that every single government in the world agrees with this narrative should convince most people. Anyone who doesn't buy it is a conspiracy-theorist and a crackpot. And if they ask why the impact sites are radioactive, well, the asteroid had lots of uranium in it. ]
[Question] [ Potions have been the traditional solution for medical issues throughout history for populations within witch society. Witches were seen as the doctors of their community, treating people with various ailments (anxiety, pain, muscle spasms, etc.) with their magic brews. This excelled even further in the modern age with the rise of the pharmaceutical industry, with various companies competing with each other for customers. Gone are the days when people visited some witch hut in the woods. Today they can go down to their local pharmacy, stacked with drugs from corporations who produce them. Potion making is difficult and requires much preparation, which can take months or even years depending on the factors. Ingredients must be gathered and brewed in particular ways, requiring a skilled specialist who demands a high price for their services. Corporations spend billions of dollars a year making and promoting new potions, then selling them at premium prices to make back the cost. This can get very expensive, and keeps them out of the hands of less well-off customers who can't afford the high prices. In addition, they are bulky to carry around, and difficult to conceal. Who wants to pull out a glass container at the dinner table when one's symptoms are acting out? The industry has therefore determined a way to make the selling of cures more affordable to reach the hands of more customers. The obvious solution to this would be to sell medication in pill form. Pills can easily be produced in large quantities for pennies and then sold at outrageous prices. Sometimes meds can be sold for hundreds of dollars a pill, such as Valium, resulting in enormous profit for the companies behind them. They are small and easily packaged, allowing for discretion and lack of shame for its users. On the verge of a nervous breakdown? Sleep deprived? Popping a Voldemortsium will cures what ails ya! These miracle drugs can take the industry to new heights, produced cheaply, in bulk, and sold at premium, racking in billions of dollars a year. This makes perfect business sense, and it would be foolish for any CEO worth his salt to not capitalize on this moment. What would prevent the pharmaceutical industry from producing their products in bit sized form? [Answer] ## Because potions are already in a concentrated form Most liquid medicines manufactured by modern pharmaceutical companies can be turned into pills because the liquid form is often less than 3% active ingredients. Not so with potions. If a potion is instead made up of 30% active ingredients, then turning that potion into a pill would require a person to swallow something uncomfortably large. We already see this with some medicines like certain cough syrups and antibiotics where they are still more popular in the liquid form despite there being a pill because the pills are just so darn big and hard to swallow. If you amplify this so that pills would have to be the size of golf ball (or taken in the form of 20 normal sized pills), just to contain all the active ingredients, then the liquid form would remain the preferred delivery system by consumers. [Answer] **Potions are alcoholic.** Potions are [tinctures](https://en.wikipedia.org/wiki/Tincture) because they need to be, for solubility reasons. It is difficult to encapsulate a tincture in an edible capsule - the ethanol makes its way out of the gelatin capsule. Capsules usually contain dry ingredients or ingredients in an oil base. Even plastic containers struggle to contain ethanol. For tinctures it is going to stay glass. [Answer] It's simply not possible by the Law of Similarity. Like produces like. A small, insignificant pill has a small, insignificant effect. Besides, in a culture where potions are commonplace, taking a potion is no more shameful than popping a pill. Bulk is an issue, but perhaps a bag of holding can be devised. [Answer] *Magic is not amenable to mundane chemistry.* A [pill or tablet](https://en.wikipedia.org/wiki/Tablet_(pharmacy)) takes the active compound(s) with expicients to simplify handling and to assure a consistent dosage. That's the result of a modern, scientific world view, and in a magical world it works for those who believe in it. Just as homeopathy sometimes works for those who believe, even if scientists would say that people are [ingesting pure water](https://en.wikipedia.org/wiki/Homeopathic_dilutions#The_molar_limit). So if the potion-based pill doesn't contain a spoonful [eye of newt](https://en.wikipedia.org/wiki/Salamanders_in_folklore#Newts_in_witchcraft), it won't work. And if it does, it is not a *little* pill any more. It is a digestible container for the original potion. For a certain volume, a flask is more convenient. [Answer] **Pills have much shorter shelf life than equivalent potions.** The liquid components of potions act as a buffer to reduce the thaumaturgic dissipation of the potion's magic. The pills, since they encapsulate all the effects of the potion into a small space, also have a much higher thaumaturgic energy density than a potion, which makes the dissipation problems even worse. Adding the necessary stabilizers to pills to lower the dissipation to acceptable levels is possible but adds too much to the cost to make them practical to sell to the average consumer. [Answer] This is one of the first things that Witch Apprentices learn. Human Medicines have to be Water Magic as Humans are 98% water, therefore these medicines have to be in Liquid Form (ie potions). Dry crumbly pills work great for Trolls and other creatures of Earth, while gaseous concoctions are needed to cure Fairies and other WindSprites. Similarly Dragons and other creatures of Fire Magic need enchanted Flames to cure them. [Answer] The law will prohibit it. It is more or less what happened with [LSD](https://en.wikipedia.org/wiki/Lysergic_acid_diethylamide#History) > > Sandoz Laboratories introduced LSD as a psychiatric drug in 1947 and marketed LSD as a psychiatric panacea, hailing it "as a cure for everything from schizophrenia to criminal behavior, 'sexual perversions,' and alcoholism." The abbreviation "LSD" is from the German "Lysergsäurediethylamid". [...] On October 24, 1968, possession of LSD was made illegal in the United States. The last FDA approved study of LSD in patients ended in 1980, while a study in healthy volunteers was made in the late 1980s. Legally approved and regulated psychiatric use of LSD continued in Switzerland until 1993 > > > [Answer] ## Hexes and Curses The witches that don't want their potions to be mass produced due to [Intellectual Property](https://www.wipo.int/about-ip/en/) concerns will threaten (and likely perform) hexes and curses on the company and/or CEO to make sure their [rights](https://www.law.georgetown.edu/your-life-career/career-exploration-professional-development/for-jd-students/explore-legal-careers/practice-areas/intellectual-property-law/) and property are not used against their wishes, and at a loss of personal profit or reputation. Witches, even the good ones, aren't known for their willingness to share their recipes. These are closely guarded [trade secrets](https://www.law.cornell.edu/wex/trade_secret) that have been kept within the family for generations/centuries. These usually aren't for sale. Some witches might have sold out, but others don't want to. The ones that don't want to sell will have lots of various reasons for not wanting to, but hexes and curses will be the way they keep their spells and potions from being commercialized. Forget lawsuits, no one wants the "forever food poisoning" curse. That's just nasty and a really rough way to die. A CEO might not care much about losing a couple million in a settlement, but they aren't going to stand (or sit) for 24/7 simultaneous vomiting and diarrhea. [Answer] **They work too well** The magic potions actually cure what ails you. That means... You don't come back as a repeat customer. So you spend billions of dollars coming up with your magic impotence cure, say, and instead of Viagra where people buy lots, people pop one and never have to take one again! Where's the profit? [Answer] **They don't know what the potion is for** > > Witches were seen as the doctors > > > Yes. They listen to their clients and they try and understand what the clients need. But unlike modern doctors when they choose which potion to give to a client they don't explain what the potion is doing or which part of the body it is going to heal. The magic is not just curing something, but choosing what to cure. [Answer] **Too many customer complaints** ...For example: LS, Your Arthrosis potion B5612 does not work. You modern folks don't know what you're selling. When I was young, the potion was brewed by the witch and the cure took place in the presence of the witch. The witch would put *fresh* frog toes for Arthrosis, perform the spells needed, adding to the confidence of the patient.. Nowadays, you think your little flasks will do, without the spells, with only fermented frog toes in it.. and some wiseguy on WB is even proposing pills. Dream on ! The frog toes would be grinded and dried out completely, be unrecognizable.. I called it out for years, but you won't listen. You'll end up with millions of witches not being cured, because they don't believe it can work. small k regards, Lizella Mistletoe, CA support Witch corp. *(Note: Letters like the above we receive every day, about our products. Of course, the active substances in B5612 are tested and balanced, frog toe extract IS part of our medicines, spells ARE carefully recorded and played back live, before packaging the capsules. When (ever) we're going to make pills, we'll test these pills too. But we'll have to slow down our developments now. Too many complaints from Google-witches who think they know it all. They don't grab our methods. And lots of witches have now resorted to alternative medicine instead. The discussion about these pills is very bad for sales. We expect this to cancel the pill project, at least for the foreseeable future)* [Answer] I think "arbitrary cultural preference due to historical quirk" is a valid possibility here. Even in our universe, pills are not universal. Medications for children are often provided in a syrup form. Pharmacies can prepare pill or powder forms into syrups or liquids for ingestion. Consider cough syrups. They're almost always syrups. No reason they have to be. Could be pills. And pill forms are available. But that's just not what most people are used to. Similarly, people in many cultures associate injections with greater effectiveness. It's routine in some countries for antihistamines, antibiotics, etc. available in pill form to be injected. Equally effective either way but the patients prefer that. If medicines always came in liquid form, I would be a little leery of some pill. Why isn't it a liquid like it's supposed to be? Perhaps the attitude is re-enforced by a folk-misunderstanding of the medicine involved, like a belief that medicines have to mix in the blood to be effective, etc. [Answer] # Big Pharma is afraid of witches. Witches are vengeful, and aren't keen on someone stealing the secret recipes of their potions. Big Pharma seeks wealth, and the last thing they want is to make enemies with a witch. Once it becomes known that Big Pharma's pill is made from the secret recipe of a witch's potion, it won't just be one witch they'll have to deal with - all witches will see them as a threat. Game over Big Pharma. [Answer] # Because magical ingredients are so scarce and magical potions have such short shelf life that it prohibits any economy of scale and mass production. As inspired by the *Shadowrun* universe: magic can cure some ailments that medicine cannot (or at least not as effectively/accessibly). Unfortunately, spells bound into alchemical products * only affect a single target (or possibly all targets within a small area) once, * have a very short shelf life in the range of hours (up to a couple of days by the most skilled alchemists with access to the rarest alchemical ingredients), too short (or too rare) to be packaged and shipped at scale, * often require active ingredients with a shelf life (usually hours to days and anti-proportional to the product’s potency) that cannot be mass-produced because their production/growth drains “mana” from its environment which is locally scarce (yet regenerates over time), * always require a piece of the alchemist’s strength proportional to the product’s potency and shelf life duration (in the same way as strenuous mental or physical work, i. e. it regenerates over time given basic sustenance or, in more severe cases, standard medical care), and are thus unsuitable for mass production and distribution. (There are ways to alleviate the aforementioned scarcities but they require literal human blood sacrifices or other kinds of highly unethical and/or highly destructive behaviour which are quite “frowned upon” in most parts of the world.) This leaves room in the market for “witch potions”: * An alchemist in a sufficiently large community might optimistically prepare alchemical products with a predictable demand, e. g. a hangover cure on Monday mornings or an instant gunshot wound cure in times of (gang-related) warfare, for immediate pick-up. Ingredients harvesting and delivery are planned accordingly. * Otherwise, all alchemy is *bespoke* and only accessible to whom it can be delivered within a couple of hours after production. This leaves the alchemist’s regional community. At most, one could organise a distribution system like we have today for organ transplants: put them on the next flight and charter one if you have to. But this only works if the alchemist and the customer are near suitable start and landing zones, usually urban centres with commercial airports, which is normally at odds with the next point. * In a similar vein, ingredients are much easier to source locally. Unfortunately, densely populated or polluted environments, i. e. most urban centres, are ill-suited for the growth of all but the most common alchemical ingredients. This leads to an economic advantage for “witch huts” in forests or abandoned areas even though it makes distribution harder since, obviously, most customers do not live in unpopulous areas and high-speed transport (e. g. aeroplanes) is equally scarce there. [Answer] Isn't that what [Big Natura](https://www.nbcnews.com/id/wbna31188920) does? [Answer] I don't think it's really possible if there's *one* active ingredient. Even if that active ingredient needs to be liquid, it could be contained in something like a soft-gel which contains the liquid. [![enter image description here](https://i.stack.imgur.com/TWXym.jpg)](https://i.stack.imgur.com/TWXym.jpg) Regardless, I don't think the previous answers (that there isn't enough active ingredient or it needs to be dissolved in alcohol for solubility) are compelling. My insight mostly comes from having interned at a pharmaceutical company which was dealing with bioavailability and solubility problems. Most of the time, the reason why some active ingredient is present in some large amount is basically because the body doesn't uptake it very well: ie it literally is not that soluble. The solution that some [clever lads from Australia came up with](https://www.churchillpharma.com/technology/) is relatively new and [patented](https://patentimages.storage.googleapis.com/0b/3b/e4/ffdc4946500f5a/EP2969227B1.pdf), but the gist of it is just to take what you have and smash it into extremely tiny particles to improve the surface area-to-volume ratio. Using alcohol to keep something in solution merely just places whatever is dissolved in it into precipitation when the alcohol is absorbed by the body. I would probably do something with two bottles (or one bottle with an internal division). Basically, two things magically react, and you want to administer them at the same time so that the magical reaction occurs inside the body. While this could be done with two pills, pills being solid could pose some issues with intermixture. Alternatively, one of the ingredients might only be a liquid at room temperature (eg ethyl alcohol). [Answer] ## How things are digested matters. Chemicals are frequently delivered in pill form because they are designed to be digested and absorbed by the body at a given rate - that's the reason for all those 'inactive' ingredients in a pill. A chunk of the pure substance (active ingredient) the size of the pill would probably kill you in almost all cases - at the very least it'd all hit you at once and then the effect would be over. So, just as pills are specifically designed to stretch out the effect of their active ingredients, so are potions designed to do the opposite. In order to function, the reagents of a potion (both material and immaterial) must be digested / consumed and inside of a human body, and reach a certain specific concentration within a specific timeframe. If that happens, a spell is cast with the drinker as the target. If it doesn't, the spell doesn't become cast - it may not have enough of the right magical energy, or it might need to use some property of a reagent, or have the person who drank the potion be a specific amount of drunk, etc, but for whatever reason, if you change that formula the spell doesn't work. Perhaps it is possible to invent a spell that would have the same effect but might be triggered via some other, slightly different conditions, but nobody has found a reliable way to do that yet. [Answer] **Because it isn't perfect business sense** One of your assumptions is that a pill will be just as effective as a potion, that they can be produced in bulk, and that they can be made cheaply. But what if that is impossible? It seems very simple to me; in order to get the magic you need in a pill, you either need more potent ingredients or a whole lot of ingredients to convert into a concentrate. Or, maybe you could just buy a bunch of potions to convert into a concentrated pill form. **What does this mean? Making pills isn't as cost-effective, especially when making them in bulk. Where pills shine is when someone with a whole lot of money wants something small, transportable, and highly concealable.** **Otherwise,** maybe pills are just dehydrated potions, or potions made without water; highly effective, but since water is needed for potions to be absorbed and utilized by the human body, they dehydrate the user, requiring them to drink massive amounts of water or else they shrivel up like a raisin and die. Either way, I hope this helps! [Answer] Magic simply does not work that way In chemistry, you can always reduce to the active ingredients that achieve the desired effect, allowing you to produce a tiny little pill. But magic is different. Magic is incorporeal, and the effect of the potion is the result of unique interactions between the magical aspects of all its components--including the liquids. Even the form of the liquids matters. Ice, for example, is magically different from water. And the magic of a potion is not just the result of the potion's *current* state and ingredients. Each step of the process--adding ingredients, removing them, freezing or heating--cultivates changes to the potion's magical properties without introducing instability. If you make the wrong changes at any step in the process, or even fail to make the right changes at the right time, the magical properties you have so carefully cultivated will become unstable and collapse, rendering your potion worthless in the best of cases. This applies just as much to the finished product as it does to the potion's creation. Instead of crafting something physical from physical ingredients, you are using the innate magical properties of your ingredients the sculpt something purely and inherently magical, without ever being able to see it. Pull the wrong thread, and it all comes unraveled. Some magical elixirs can be made solid. Some even as small as a pill. But each potion takes the form it *must* take. You cannot change a potion into a pill without brewing a completely different potion, with a completely different formula, which happens to have a similar effect--and very few have been discovered that are magically stable in solid form. No, you cannot simply turn a potion into a pill. That would be base chemistry. ]
[Question] [ It is 1950. I am a rich and crazy entrepreneur, who wants to replace pens with typewriters. I can try to influence (or lobby) any government in the world. I want my typewriter to be cheaper than pens, although that typewriter may have an extremely limited set of glyphs. With the hindsight available to you people (from the 21st century) is there any practical way for me to achieve my ambition? 1. I am willing to use any major writing system for my typewriter. The term 'major' here is intentionally vague, and means that it is used by millions of people daily. 2. I want millions of ordinary laymen to replace pens with my typewriters. It need not be a worldwide success. 3. I want my typewriter to be cheaper than pens. 4. I want this to happen in 20th century. --- A combination of the answers from Monty Wild and user535733 is the best choice. I am in a moral dilemma that it is not possible to select them both. A modern version of index typewriter marketed using a loss leader strategy might be the best option. I still welcome better ideas, or more historical examples for such attempts, if any. [Answer] **Index Typewriters** [![American index typewriter No. 2, 1893, image courtesy of https://site.xavier.edu/polt/typewriters/american.html](https://i.stack.imgur.com/mmgYk.jpg)](https://i.stack.imgur.com/mmgYk.jpg) Photo source: <https://site.xavier.edu/polt/typewriters/american.html> Index typewriters tried to solve this very problem: Typing for household and occasional use. The user must use two finger movements to type each character (instead of one), which slows typing...but reduces the number of parts required and the corresponding cost. They were popular 1880-1920, and cost around 5% of a classic business typewriting machine. Portable models existed. Of course, these examples of 120-year-old machines cost more than a pen of the time, and take up more pocket space. Your inventor must do a bit of the *inventing* work themselves. [Answer] The manufacturing cost of the cheapest pen is never going to be more than the manufacturing cost of the cheapest typewriter. In fact, the manufacturing cost of an average pen is never going to be more than the manufacturing cost of the cheapest typewriter. Typewriters are *complicated*. However, the disparity in cost between pens and typewriters need not be an obstacle to typewriters becoming ubiquitous. The *sale* price of items need not reflect the *manufacturing* cost of that item. With sufficient funds or other sales, the manufacturer of typewriters could sell their cheapest, simplest model for less than the sale price of a pen. Why would they want to do that? As a form of advertising. Sell the basic model so dirt-cheap that everyone who might be considering buying a pen will seriously consider buying one of these typewriters instead. How could a manufacturer *afford* to practically give away typewriters? Higher-grade models and consumables. Sell both for a large markup to cover the manufacturing costs of the cheapest model. Additionally, a manufacturer could give basic typewriters to schools to encourage the teaching of typing, and teach the latest generation to prefer typewriters. Why, when a basic typewriter is so cheap, would anyone buy a much more expensive model of typewriter? Put simply, the much more expensive models would be much easier to use, with lighter keystrokes, better placed controls, capable of more things, and with a range of much nicer, more readable fonts than the ugly font used in the cheapest model. [Answer] ### Allow me to introduce the [Berwin toy typewriter](https://www.kshs.org/index.php?url=km/items/view/222150)! Your timing is impeccable! In 1950, pens were *not cheap*. Typical pens of the time cost several dollars. These, of course, were fountain pens. The biro had been introduced a few years before, but were far more expensive. Seeming to be the natural descendant of the Index Typewriter mentioned in another (excellent) answer, this little tin litho toy will fit your bill perfectly. [![enter image description here](https://i.stack.imgur.com/Fqb04.png)](https://i.stack.imgur.com/Fqb04.png) All you have to do is turn the type wheel and press a key that pushes it towards the paper! Unlike standard business models, there are hardly any moving parts here. The keys are just litho decorations. The original price was probably a dollar or so. If you need a much smaller, even more portable device, then check out the [Cole-Parmer printer](https://www.coleparmer.com/i/cole-parmer-manual-laboratory-label-maker-tape-blue-3-8-x-118/6554348?PubID=UX&persist=true&ip=no&gclid=CjwKCAiA5t-OBhByEiwAhR-hmz5X5D4iNxgZpDhsJoeup76Rdm9Ps1fQ2sBmmfegk6royb7OEbmYlxoCdDAQAvD_BwE)! It operates on the same basic principle as the previous, turning a little print wheel and pulling the trigger to impress the letter into the plastic strip medium. Even in our time, first quarter of the 21st century, they're cheap! Twelve dollars now is approximately the same as your every day Franklin half dollar! [![enter image description here](https://i.stack.imgur.com/dlmSw.png)](https://i.stack.imgur.com/dlmSw.png) --- # From Comments: Need directions? Just type them out! Adding up a bill is trivially easy. Integrate either device with an "Add-a-Matic"! [![enter image description here](https://i.stack.imgur.com/pdiDB.png)](https://i.stack.imgur.com/pdiDB.png) [Answer] # Put their eyes out. Your handy (patented) Braille ring doodads (which make a typewriter-like clack as the spring tension rams the mold into a substrate such as a softened wooden or bamboo strip) allow trained users to produce Braille glyphs quite rapidly, and they can read them better than a letter in pen. (To save time on the blinding, you might consider spiking their polio vaccines with some sort of toxic alcohol akin to methanol or ethylene glycol, but slower acting and more potent ...) [Answer] There's only one way to get *everyone* to quit using pens, which is what will be needed to transfer everyone over to typewriters. ***Law*** *Draconian* law. First, you'll ensure that all typewriter manufacturers are prepared to run three shifts at maximum capacity for a period of years, until the need for writing instruments is filled. Second, you'll place a legal prohibition with severe penalties on the manufacture, import, use, or mere possession of any kind of pen, stylus, pencil, or crayon (sorry, kids, but coloring is more fun with watercolors and a brush anyway). Ink, too. Our modern society's "War on Drugs" can be a fine example of how well this can work. Third, you'll similarly outlaw *teaching* handwriting or even manuscript block lettering -- if people know how to do it, they find ways to make the tools. Sadly, pens are so simple that they predated the invention of anything you might reasonably write *on*, and ink isn't much harder. Now, prepare to take on organized crime for at least three or four generations, because where there's a demand, *someone* will step up to fill it. In the end, even if typewriters are *free*, and with all the above measures, I doubt they'll replace handwriting -- they're just too heavy to carry around, where a pen only weighs 15-30 grams and fits easily in a pocket or can even ride behind your ear. [Answer] Can't happen you have three major problems 1. Cheaper is nothing, they also need to be smaller and lighter than a ball point pen. I can put a pen in my pocket and write on any document I come across. 2. People need to learn typing before they learn handwriting, a large number of people will never learn both, so you need teach typing before hand writing, which means you also need to replace pencils, crayons, chalk, and markers. 3. The last nail, I can draw with a pen, that alone makes a pen far more useful. I can underline, circle, sketch, trace, I can write on skin, wood, paper, cardboard, pictures, ect. I **draw** a map, or a cartoon, or a **math** problem or chemical formula, I can make a **diagram** or draw an arrow, or thousand other things a typewriter cannot do. I can write in **multiple languages** with the same pen. A pen is a far FAR more versatile tool. A typewriter cannot replace pens because it can't do most of the things a pen can do. The people who could benefit from a portable typewriter already had them, basically just people who needed a single dedicated machine for writing large amounts quickly in a single language, but they still carried pens for corrections, sketches, or a dozen other uses. the typewriter is too specialized to replace a general purpose tool. It is like asking a farmer to replace all knives with axes, or replace paper with audio recordings. [Answer] First, you realize pens are inherently portable. So the first step is to make the typewriters small enough to be easily portable. With a genius-level foresight (or a dumber than dumb 21st century hindsight) it is clear that mechanical typewriters will not quite fit the bill - electronics is the way to go, especially the newly discovered [semiconductor devices](https://en.wikipedia.org/wiki/Transistor). Something [like this](https://en.wikipedia.org/wiki/IBM_Selectric_typewriter), replacing the hard to operate mechanical construction with an electrically operated printing ball and an easy to type keyboard s an improvement: [![IBM selectric](https://i.stack.imgur.com/xIs4a.png)](https://i.stack.imgur.com/xIs4a.png) Still too heavy. So then comes [the next model](https://en.wikipedia.org/wiki/Silent_700): [![Silent Writer](https://i.stack.imgur.com/uJ9I4.png)](https://i.stack.imgur.com/uJ9I4.png) That's better, but for quick notes, paper is still cumbersome, big and heavy (in reasonable quantities). Replacing the paper with [a built in display is an improvement](https://en.wikipedia.org/wiki/TRS-80_Model_100): [![TRS80 model 100](https://i.stack.imgur.com/zsdpU.png)](https://i.stack.imgur.com/zsdpU.png) It *could* be [made smaller](http://www.pc-1500.info/), but then typing would become more difficult. The next step is to make these (first luggable, then portable, or perhaps even pocket) typewriters to be widely accepted and used by the population worldwide. Granted, with prices getting low enough, these will be used, but mostly by enthusiasts and typewriter geeks. So, in addition to writing down notes (which is the main use of a pen), what can our typewriters offer as their killer app? Well, we people are social beings, so the ability to communicate remotely... while [nothing](https://en.wikipedia.org/wiki/Telegraphy) [new](https://en.wikipedia.org/wiki/Telautograph) [under](https://en.wikipedia.org/wiki/Teleprinter) the Sun, making it ubiquitous and portable (and with some far reaching imagination, even [wireless](https://en.wikipedia.org/wiki/Pager)) would have some appeal... So, after some iterations, your typewriter fits into a pocket and either has [a reasonable keyboard](https://en.wikipedia.org/wiki/Nokia_9000_Communicator), but a bit heavy: [![Nokia 9100](https://i.stack.imgur.com/q2Kgp.png)](https://i.stack.imgur.com/q2Kgp.png) through [smaller](https://en.wikipedia.org/wiki/Nokia_E61), but still very usable: [![NokiaE61](https://i.stack.imgur.com/QCCPr.png)](https://i.stack.imgur.com/QCCPr.png) to the poor man's typewriter with a limited keyboard, requiring [multiple presses of a key to enter the desired letter](https://en.wikipedia.org/wiki/T9_(predictive_text)): [![Nokia 3310](https://i.stack.imgur.com/69xAo.png)](https://i.stack.imgur.com/69xAo.png) And who knows where the future development leads, but one thing is clear, the devices will have a keyboard - although we can [imagine technological development](https://en.wikipedia.org/wiki/Touchscreen) to allow us other input methods, who would want to write on anything that is slower, error-prone and clumsier than a keyboard? That's for the [two way written communication](https://en.wikipedia.org/wiki/SMS)... but can we do better? Obviously, N-way (where N>2) is better - imagine a worldwide network, with hundreds, nay, [thousands of discussion groups](https://en.wikipedia.org/wiki/Usenet), where you can type you opinion, read the responses from your peers on your pocket typewriter screen, even communicate in real time... I can imagine this to be the major timesink and a new most indispensable thing since the television. And once this becomes widespread, people will use handwriting (and pens) less and less and eventually even [the school system will catch on](http://www.bellaonline.com/articles/art26073.asp). And, if the development starts with the transistor and continues in [its natural leisure pace](https://en.wikipedia.org/wiki/Moore%27s_law), prompted now and then by generous investments in the right spots by your entrepreneur, and if in the 1950 he is young and healthy, with a bit of luck he might live long enough to see his dream come true. [Answer] **Typesetters Guild** The typewriter will always be more expensive than the pen. Your business model is that, once the guild is established, it can lease a typewriter and typist for cheaper than a pen and scribe. Why are typists so cheap? It is because you recruit your typists from poor families. It is easier and cheaper to train a classroom of typists to type neatly and quickly than it is to train them to write neatly in cursive script with flowing letters on old coarse paper using a fountain pen -- without them nicking the pens. You don't have this problem with nicking typewriters because they are big. You save money on manufacturing the first load of typewriters, by selling them to the library, for the purposes of making copies of books. This is extra cheap since the duplicators don't even need to know how to read. They just do it letter by letter. More money is saved by mass-producing typists in factory schools. For example students have to correct each others' work to save on teacher costs. The largest overhead is actually the price of paper. To alleviate the price of paper, you re-use each sheet several times. First with pale grey ink, then medium-grey over that, and so on until the last use has black ink. Extra points if part of the schooling process is to copy a book from the library. You make more money by selling the copy to the library than the cost of training the student. [Answer] There is no question in my mind, how best to do it. # British Empire, especially its Civil Service The British Empire dominated world politics during the first part of the 20th century. It set social and cultural norms for countries from India and what's now Bangladesh, to the Carribean and much of Africa and Micronesia (Pacific Isles). It's why the Indian Civil Service is so desirable to get into, why English is so global, why countries worldwide wear British clothing such as bowler hats or shirts that weren't part of their traditions, and many other things. If you want typewriters to overtake pens, mandate it to your colonies. You have at least 2 angles: **Cultural pressure:** If the British do it, others will see which way the wind blows. It'll be too shameful to not have that skill. Parents from remote Indian villages to Jamaican mansions will slap their children's hands for using a pen *("Do you want Teacher to laugh at you? You want a job as a chai-wallah/sugar worker? What girl/boy will marry you if people say you use a pen!?"*). Rich people will acquire tutors for children poor families will indenture themselves if needed for one shared between them, so their kids can have a cjance in life and not be shunned. You can influence it in schools, police, government offices, the works.... **Formal requirement:** its part of the prestigious Civil Service Entrance Exam. Its mandated by government practice documents and required of anyone who works for them. If you know history, you'll know just how hard people drove themselves to get such jobs, meet such demands. And yes, let them indenture themselves. Its cruel, but embeds it even harder in the culture. What you have to sacrifice for, you are even more determined won't prove wasted. [Answer] ## Get schools to only teach typing Typewriters may be much more complicated than pens; but handwriting is a much more difficult skill than typing. Donate generously to the top political party/parties to "prepare pupils for the future" by dropping slow, archaic, difficult to read handwriting for modern, efficient typing. Buy millions of typewriters for primary schools, and get them while they're young, and they will never learn to write using pens. [Answer] ### Widespread hand damage/deformities Ironically enough, I just read [this story on the BBC news about the 1921 census](https://www.bbc.co.uk/news/uk-59879470). Everyone filled out their census form in handwritten ink - apart from an ex-soldier who did it on a typewriter. Part of his right hand had been blown off during the war. You can invent your plot-based reasons for this. But if you don't have hands that can grip a pen, a typewriter is your best option. Sure, people do use their mouth or feet instead - but a typewriter where you can simply hit the relevant key with any available body part is simple, reliable and useable by everyone, with guaranteed readable results. [Answer] ## Too Many Lawsuits You're not going to make the cost of making a pen less than the cost of a making typewriter, but you may be able to make the cost of pen **ownership** higher than the cost of owning a typewriter. In the time leading up to your story, contracts, deeds, wills, etc. were still by-in-large hand written. Now imagine someone got a lot of publicity successfully suing to break a contract over the argument that his handwriting was too illegible to be understood by the person signing the document. This leads to a series of lawsuits that get more and more ridicules as business arrangements of all kinds come under litigation leading to untold billions of dollars in damages left and right . It gets so bad that insurance company's and law makers adjust thier polices around pen use being seen as a high-risk behavior. Basically your civilization goes cancel culture on all things hand written. So sure, you can still buy a pen as a "novelty item" and it's still cheaper than a typewriter, but the second you move into "real world applications", the liability of using a pen for anything is so great that after all the fines, pro-rates, riders, and excess taxes associated with them make them more expensive to own than the typewriter. ]
[Question] [ We have modern humans found in a near future, first world country on Earth. The primary technological advancements are in the form of extremely cheap and fast genome sequencing ($10USD/genome) and in the inexpensive use of [CRISPR](https://en.wikipedia.org/wiki/CRISPR) gene manipulation to fix any and all defects. This gives everyone the capability to know what their genome contains and a means to make any changes to that genome. Gene manipulation techniques become quickly and highly regulated. For the first few years after this treatment became available, only fixes to genes considered defective or [disease causing](http://www.genome.gov/10001204) are eligible for correction. Changes to appearance or musculature are not permitted. Those found to receive these treatments are punished by resetting to their previous state. Organization such as WHO and other NGOs have successfully made this treatment available to 99.9% of the world population. (Yeah, a miracle.) Now, the world is healthy and free of all genetic diseases. As children are born, they are tested and treated so no diseases are reintroduced into the gene pool. Under considerable pressure from cosmetic surgeons and the populace in general, the regulatory body for gene treatments has permitted the genetic manipulation of appearance. As the treatment is ubiquitous across the world, anyone can manipulate their genes to alter their appearance to anything they please. Therapies that alter a person's brain or brain chemistry are forbidden (let's assume perfect enforcement). --- Now, the implications of this kind of technology will touch practically every aspect of society. Every single one. I'm only interested in one particular aspect though, dating, specifically mate selection in cultures where individuals are able to choose their own mates. Arranged marriages are not up for consideration in this question. When everyone can look like a Greek god (or the local physical ideal), how will mates be chosen if physical appearance is eliminated from the list, leaving material wealth, social status, smarts and emotional intangibles as the remaining criteria? [Answer] Other answers address the obvious importance of elements other than appearance in courting behavior, so I'll ignore all that and focus on the core of your question: how does valuation of appearance change when people have complete control over it? The answer is: we'll be judged by our choices and the motivations behind them. You can already see this in the way people judge clothing choices: "that woman's clearly wearing a shirt meant to make her breasts look big" or "that guy's jeans are tight, he must think he has great legs". Natural features are currently met with disgust/pity or awe/jealousy: "I wish my nose was like hers" or "his feet are too big, poor guy". With your technology, people choose how they look, so the observations might become: "why does she raise the tip of her nose so much?" and "he must want to swim fast to keep his feet so big". Each person will become far more critical of appearances because of the level of criticism and control they direct toward their own bodies. If one person sees another making body shape choices they themselves actively avoid, the former is more likely to judge the latter more harshly and negatively. Appreciation of beauty, meanwhile, diminishes as it's commonplace and based on cultural standards leading to uniformity. With all of that pressure and the power to respond to it, we'll also see a lot of frequent adjustment. Consider the way people change their style of dress and even attitude when they meet someone they like, in order to match that person's tastes. Or how strongly some people react when they're judged negatively to their face. Cheap genetic manipulation would drastically impact those social dynamics. The concept of identity as it relates to physical appearance would become much more vague and amorphous. That will undoubtedly make conventional romance as it's presently understood far more difficult to maintain - how would you feel if the person you love the most was frequently and wildly changing? It's hard to picture the face of a loved one if it changes all the time. [Answer] I don't think things would change as much as you think they might. Looks would still play a part. Just because someone has great genes doesn't mean they take the time to maintain their body - selection would still occur based on metrics such as this. However, ask couples what attracted them to their mate, and you may find that only a tiny fraction of the answers you will receive will be "their body". It's always something they did, or some indescribable aura/aire that they have. For example, dating companies usually advertise healthy relationships by having the subjects say things like, "s/he makes me laugh, and that's why I love them". Another thing to consider is that clubs often hire Asian bouncers because they can better distinguish the faces of other Asian people. I have not confirmed this story myself, but it makes sense. In a culture where the differences between individual facial structures is smaller, they have simply become more in tune with those subtle differences. Heck... for most of us, our legs are roughly the same length. Did you ever stop to give credit to genetics for pulling that one off? Think about how hard it is for the body to measure leg length and ensure they grow evenly! Do we spend more than a passing thought on leg length when choosing a mate? There's plenty of beauty there, even before cosmetic surgery! [Answer] This already happened. I married my wife, who I met on an MMO, and I am far from being the only person this has happened to. Many, many people meet on the Internet and fall for each other online, without their physical form being relevant. Even prior to that, it happened, with arranged marriages, marriages between those who had hitherto only been pen-pals, and so on and so forth. In a computer game like, say, Second Life, you have full control over your looks... and people's looks still vary. People's *tastes* still vary. With full control over your looks, your looks just become a full expression of your personality, rather than something over which you have at best only tangential control over. So in those environments, everyone's looks don't become homogeneously "perfect" because there *is* no one version of "perfect": instead, people become more unique, more different, each struggling to find the most different and standout version of "what makes me, *me*". Your "looks" (whether you're an insanely-endowed crocodile-man or a tinkerbell pixy who propels herself by farts) in some sense can be argued to actually matter *more* in the way people evaluate you, but that's OK because *you chose them*. As a side thing: it already happened IRL too. We are currently freaking gorgeous by some historical standards. Nothing has changed. You get used to stuff. They become commonplace. If everyone is very close to the ideal, we'd get used to that, and just notice the smaller differences more. And use tattoos, piercings, jewellery, perfume and clothing to customize our looks. [Answer] You've listed genetic manipulation for the sake of disease eradication and physical appearance. As you've said, that leaves several, seemingly less tangible, options for choosing a mate such as skills, mindset, and net worth. However, I propose that finding a mate would not be that different from today. Human cultures typically create class systems. We are all of and in a social class. We are in the class that we rose to or fell to as adults, and children are in the class that their parents occupy. Class has a strong influence on how you interact with others. As the Sociology textbook "Society in Focus" says: > > Class position has a pervasive influence on almost everything… the > clothes we wear… the television shows we watch… the colors we paint > our homes in and the names we give our pets… Our position in the > social hierarchy affects our health, happiness, and even how long we > will live. > > > So it is likely people will desire a mate that is of a similar social class or higher. The question becomes: where are class divisions drawn in this near-future world? Will people marry based on wealth? Education? Occupation? Religion? A [2008 study](http://www.epjournal.net/wp-content/uploads/EP06595602.pdf) published in the journal Evolutionary Psychology found individuals desired a partner who resembled them in terms of personality. Much like your perceived social class, personality is often visually identifiable by clothing, grooming, hangouts, music, etc. Just as in today's world, a person would find a mate by looking for desired traits, and attract one by exhibiting said traits. Even though people can appear as beautiful as they desire, there will always be multiple ideals of beauty. What is the perfect nose? The perfect eyes? A [2006 study](https://www.tu-chemnitz.de/hsw/psychologie/professuren/allpsy2/Artikel/JEPHPP_2006.pdf) showed that "beauty is in the eye of the beholder"—taste in facial attractiveness is not largely shared across a population. Additionally, no matter how visually alike people get, there will always be perceivable differences. As long as there are differences, people will be able to have preferences. Suffice it to say, appearances would likely still have a huge role in meeting and choosing a mate. [Answer] It means personality would become a much more obvious differentiater. If you have two Greek gods, and one is an a$$/B!tc# and the other is a pleasant person to talk to which one would you be more willing to spend time with? Of course, there will still be plenty who are happy to take anything home, and of course plenty will still be looking for a rich partner... However, if you are rich, while you can still be a jerk, you'll be more likely to pick someone who doesn't grate on your nerves all the time, just because he/she meets some visual requirements. It means they are more easily replaced by someone who looks just as good. This of course mostly affects those who already base most of their dating criteria on physical attractiveness. Those who actually like to get to know their partners will still do it by learning who they are and finding someone they like spending time with. Oh, and even though everyone looks 'amazing' we don't all agree on what 'amazing' is either... [Answer] personality, and intellect, to name a few important criteria. Physical appearance is only one of many factors we use when choosing a mate, and arguably in the modern era it is less important to the overall fitness of our children then other criteria; evolution just hasn't gotten around to 'catching up' on that fact. Once everyone was beautiful we would simply fall back on the many other things that we use to determine who to date. Personality and how much we get along with them, how intelligent they are, how good of a provider they would be, how good a parent they would be etc etc. There are many things that effect who were attracted to. Were not all so superficial as to only care about looks. If your beautiful and a jerk, or even just slow and uninterested in learning, I would not be interested in you. I would imagine that a higher emphasis would be placed on intellect and ability to provide (which yes, means how much money you have/make) in such a society. Since money can now buy better genes money is even more important. It's okay if your husband/wife has some health issue, if they have enough money they can treat that issue in their child before it's born etc. The culture would likely grow to focus even more on ability to provide, direct income, and intellect (which almost always leads to higher potential income; especially once you can no longer rely on being beautiful to help you excel). In addition people would choose mates based off of...appearance. Just because everyone is beautiful doesn't mean everyone is equally beautiful to everyone else. We will all have our preferences, perhaps someone loves redheads, another person prefers tall women, and another things a specific ethnicity has beautiful facial features. Even if each person was an ideally sculpted appearance some would still be more attracted to certain men/women then others based off of their personal definition of beauty. Also, remember you only mentioned genetic control of appearance. Environment has an effect on appearance as well. Perhaps someone was malnurted when young and so is tiny despite genetics for height? Maybe someone over eats (or under eats) and thus a physical heavy/bone thin body? Maybe one man works out and builds muscles, and another doesn't. Maybe one person has better fashion sense while another refuses to use makeup. Environment will effect physical appearance as well. Thus, people will still be partially controlled by physical attraction, even as all the other things that lead to a romantic relationship will still drive them as well. [Answer] You mention > > As the treatment is ubiquitous across the world, anyone can manipulate their genes to alter their appearance to anything they please > > > With this advanced technology will every person want to look like 'a greek god'. I think people would branch out and get other body modifications so that there is still physical diversity. It would be the new piercing or tattoo of society. Maybe people would get tails, elongated ears, colored hair, glow in the dark skin, etc. Possibilities are endless and people would definitely go to the extremes. --EDIT-- With changes to one's "physical appearance" being open to anything related to one's genes, one's physical appearance would still take a part of dating/mate selection. Even if everyone looked like a 'greek god' would everyone wear the same clothes? Assuming people continue to remain unique then the style of one's clothing would also distinguish people from each other, and opinions would be formed. If people all look the same and dress the same then it would come down to personality. [Answer] This already happens in Second Life where people can design their own appearance. Returning to Real Life though: Movie stars do live in a world of beautiful people. Some hook up with equally beautiful people, but presumably they have their own standards of who is more attractive. Line up a row of stars and then compare them in pairs. You will come up with your personal winner. Not everyone will agree with your choice. Not all men like blondes. Not all women like conventionally handsome men. Unless the world is full of identical clones there will always be something to compare, something to prefer. [Answer] In all honesty, probably the same way people select their partners now: partly by appearances, but [ultimately by psychology](http://www.drnadig.com/selecting.htm) or for financial reasons. Let's face it, your concept of the physically ideal partner is going to be different from Barack Obama, Vladimir Putin, [Tim B](https://worldbuilding.stackexchange.com/users/49/tim-b), your siblings (if any), or me. That's one thing that makes us human: our individuality. I'm not suggesting that physical appearance is the first thing everyone uses to identify a potential mate, but it is for some people. I'm sure there are some who only care about physical appearance, but these individuals (there's that word again) probably care less about long-term relationships (at least at that point in time). Let's face it, someone even wrote a [song](http://www.azlyrics.com/lyrics/sirmixalot/babygotback.html) about liking the [gluteus maximus](http://dictionary.reference.com/browse/gluteus%20maximus?s=t). Beyond the physical, however, are the things that really matter in a long-term relationship: the psychological factors. Finding someone who looks like [Aphrodite](http://www.greekmythology.com/Olympians/Aphrodite/aphrodite.html) is all well and good (if you're into Greek beauty goddesses), but if she is a psychopath, you're probably going to seek a partner elsewhere. If you hook up with someone who looks like [Zeus](http://www.greekmythology.com/Olympians/Zeus/zeus.html) (if you're into Greek sky gods) and he is so vain he doesn't care one jot about you, you'll probably look elsewhere (especially if *you* are the Aphrodite and he's just using you as arm candy to get everyone else to look at him). As bowlturner [points out](https://worldbuilding.stackexchange.com/a/21145/6986), money can also play a role in selecting a partner. I don't really expect that particular interest to change just because we can freely alter our DNA. Still, if money is a motivator for an individual (again with this word!), there's a greater chance that physical appearance will play less of a role from the outset. [Answer] > > When everyone can look like a Greek god (or the local physical ideal), how will mates be chosen if physical appearance is eliminated from the list > > > I think this is false. When people can change their appearance as easily as they might change their wardrobe, people will still be judged and selected based on their appearance - only now the judgements are more about one's choices in this manipulation than one's genetic lottery. Keep in mind, however, that most of the people that are generally considered universally attractive have spent a lot of time and resources learning how to present themselves, dress themselves, use makeup, etc to portray beauty and attractiveness. There are a multitude of pictures of such people in their "natural" state which make them appear quite normal. [Answer] I'm surprised no one said it yet: Pheromones! One of the things that make you attractive is pheromones! This will pan out in two ways: * People will just find the “best” sequence and everyone will be the same. * People will start doing a ton more in-person, social dating. The first is extremely unlikely, since each person’s base receptors are different, so there probably isn’t one best emission. So I feel we can disregard this possibly. I’m sure it will be attempted, but those people will get regarded the way people who wear AXE body spray are now – posers, and lame douchebags. That leaves the in-person stuff. I think that what you will see is more of a group-date, casual encounter setting, people going to events where the atmosphere is quiet enough for people to talk with each other and flex their personality, since no body needs to flex their biceps anymore. You see some of this now in larger cities in the US (at least, maybe more places) where bars are set up to play board games and tabletop rpgs, comic stores have reserved space for tables and tournaments, stuff like that. Noisy nightclubs and seedy bars are designed to mask undesired physical traits, whereas in the new world, attractive is the norm. [Answer] Consider the typical college campus from the viewpoint of a heterosexual male\*. At least 50% of the women qualify as "amazing" in appearance, at least by my not overly picky standards. Yet going by my experience, only a small fraction of those are compatible enough for me to consider forming long-term relationships with them. Another point is that genetics is not the only determiner of looks. A woman might have the genes for amazing looks, yet over-eat, become anorexic, cover herself with tattoos, &c, all of which would render her unattractive to me - though of course tastes differ. \*Perhaps a female could add her viewpoint? [Answer] Current research shows that mate selection happens based on traits that we think will provide the best chance for the production and survival of offspring. Men choose women who we think will produce good, healthy, strong children. Then be able to care for those children. Good Providers and good mothers. Women choose men who they think will be good protectors, providers, and produce good strong children. In that venue, once aspect that will likely change is screening of genes before choosing a "mother/father of your children". We already do this now. When my wife and I were starting to try to have kids we sat down and reviewed our family histories to make sure we knew what possible situations would arise. With that data more prevalent, I would imagine it would become more important. A lot of other things would not change. Everybody's idea of a Good mother or good father is different. Some people like physical appearance. Some, mental stability, some confidence, some strength. If you remove one of those aspect the others (and there are more then listed here) are still used. Even today physical appearance doesn't play "that" big of a role in choosing a mate. Other aspects are measured and considered. To top that off not everyone can or would choose to look identical. Some people like taller, some shorter, some larger, some smaller, etc. Everyone's ideal of "perfect" is different. Most people look for balance. If I am strong in one area in week in area 2, then I want my wife to be strong in area 2, and if she is a bit week in area 1 then it's ok. We end up balancing each other out, and as a family unit we are stronger. This would not change either. To sum it up.. Looks are not "that important" today. In the future described they would be even less so. People would start to choose from the other traits to make mate selection. [Answer] Would it really be painless, instant, zero-cost and entirely friction-free? No. So people would stick with their looks for a while. There's an entire other discussion to be had about what this capability would do for society - photo ID becomes meaningless, race and gender-presentation entirely fluid, and so on. In the initial excitement of the technology, people would make themselves look like a narrow set of beauty ideals. However, that gets boring. There's already a taboo for women against coming to the same party in the same dress; how bad would turning up with the same *face* be seen as? (Note that there's no similar taboo for men, who are already subject to selection on non-physical factors). People would be socially expected to be different enough to be interesting. And then it's down to individual and socially-conditioned taste. Most likely relationships would be more economically assortative. If everybody is equally attractive, why not choose the highest-earning? Or if you've also eradicated income inequality, most respected/most moral/greatest musician? [Answer] With everyone looking as they want to and everyone being able to find someone that looks like they want them to look people will become bored and depressed. While people will still seek mates based on appearance the challenge/reward of doing so will be removed and thus relationships based on appearance will become less satisfying. ]
[Question] [ I have a setting that involves floating islands that coast slowly across a planet. There are multiple tiers separated by cloud layers, however the surface is inaccessible to my floating islanders. In order to suspend my floating islands I have decided to use a few different magic/handwavium particles. These particles when compressed against each other create a lifting force that pulls objects up. My islands are floated when these particles compress on the planet's surface into a giant crystal-like structure with a very specific internal shape. Pushing the land within a certain radius of said crystal up into the sky. Based on crystal factors such as crystalline structure, mass, size etc. different islands are floated at different altitudes and coast with different speeds. These altitudes are by and large fixed with allowance for some bobbing up and down. Nothing more than 100 meters at the most. The inhabitants of my world mine these crystals for airship-like flight. When mined these crystals no longer hold their solid structure, rather they break down into a sludge-like liquid which is placed into a rigid cylindrical container with a few other magic/handwavium particles. When compressed inside said container, the particles excite and effectively lift the container up. Height is controlled by changing how much pressure the pistons inside the container generate. The end result is essentially a rigid airship, only that it can lift/repel much heavier cargo and cabins off the ground and into the sky. Effectively steampunkesque airship design. If the sludgy liquid is allowed to decay into a gaseous state using another process, the lifting potential is much higher and more efficient. Pistons still control height. That said, orbital height, or even getting past the highest of islands, is impossible. A solid crystal structure is needed to get very high, something that my people haven't figured out how to recreate, nor will they ever. Refueling also needs to take place as the sludgy liquid or gaseous mix eventually dissipates. Note that solid crystals that islands use to float do NOT have this problem. The main issue I have, however, is that the people of my world can construct artificial islands using these particles and processes. Something like a floating city or an artificially created floating island would be possible if they arrayed multiple containers. I explicitly want all my people living on naturally floating islands. People flying about on airships or flying carriers are fine. But something like floating Manhattan isn't. **How do I stop people from creating artificial islands using the magic/handwavium particles that suspend my floating islands in the first place?** Notes: 1. The particles only lift things to a certain height; they don't impart lateral direction. Airships need things like propellers or engines to change direction. Islands using crystals coast around the world of their own accord and aren't subjected to this limitation. 2. Refueling needs to occur for such particles. They don't last forever. 3. There is powered flight already, the jet engine has existed for a while. These don't use the above particles. They're normal aircraft by all accounts. 4. The first airships were very steampunk in design. Rigid airship frame with a boat like frame slung underneath it. Thus, any changes to things like atmosphere, winds, etc., must allow humans to still breathe and live. 5. The largest ships are flying aircraft carriers of sorts that can launch fighter jets (think the sizes along the F14 or A5). They are used for expeditionary mining or warfare operations in conjunction with an airship fleet. There are jet cargo aircraft as well. 6. Naturally floating islands will never hit each other. Edit: The primary end goal in all of this is to stop my floating islanders from expanding past their home island with the physics and technology available to them. Expanding in this sense means living perpetually. Things like airship carriers are not part of the scope in this regard. [Answer] ## Nobody would build on an island that requires refueling There are people in the real world who are afraid to fly, because they know that airplanes can crash. Even those of us who are willing to spend a few hours on an airplane occasionally would balk at becoming *permanent residents on even the most reliable airplane.* --- You say: > > Refueling also needs to take place as the sludgy liquid or gaseous mix eventually dissipate out. Note that solid crystals that islands use to float do NOT have this problem. > > > Since your people can't create crystals, but only sludge, that means any artificial floater must be refueled. **In other words, every artificial island will eventually crash unless people repeatedly intervene.** No sane person would be willing to spend any significant amount of time on an island that might crash. Nobody will build on it. Nobody will live on it. Nobody will take a job working on it. Human projects fail all the time. Sometimes our plans just aren't good enough to provide a service that is perfectly uninterrupted. Even when our plans are good enough, *we* often are not: every human institution is vulnerable to incompetence and corruption. There's already competition for the limited floating resource. What happens when the combined consumption of all airships plus all artificial islands is greater than what is available? A lot of people would need to have an absurd amount of faith in people and human economies in order for artificial islands to be viable. [Answer] Q: People flying about on airships or flying carriers are fine. But something like floating Manhattan isn't. How do I stop people from creating artificial islands using the magic/handwavium particles that suspend my floating islands in the first place? A: **however the surface is inaccessible to my floating islanders.** You answer in your question. The land they have up in the islands is all the land that they have got. They cannot go down and get more nonfloating land because the surface is inaccessible. They can carve up the islands they have got. They can stick a few of them together. They can mine ore from a floating island and make an airship, or a building, or belt buckles. But they cannot go down and get a huge new island and float it. [Answer] # Island Big Boat Small Your floating island needs a million times more crystal fuel than a large airship to stay afloat. It also needs a billion times more metal and a trillion times more stone and earth to stand on. We do not have that much stuff to spare. Add to this how -- unlike an airship -- the island needs to be constantly refueled. I propose the airships can sit on the ground all day and not use the fuel. When they land, they open the hatch on the crystal container. The sludge is no longer compressed into the right shape, and it loses its levitation powers. It also stops evaporating. [Answer] ## Winds and currents Here's a question for you: humanity can make boats. We're pretty good at making boats. We've had thousands of years of practice, and we can make everything from canoes to supercarriers. Massive oil tankers, haulers that can move whole oil wells, all sorts of fun stuff. So why can't we make an ocean-going *city*? We can't do it because of dynamic forces. Waves, water pressure, buoyancy would conspire to make a mockery of our efforts. The forces that can be brought to bear on such a large structure are just too much to handle. So it is here. If you had a super-gigantic airship, it would be far too large to be rigid, and composed of too many chaotically moving parts to survive. [Answer] # It's Impractical There are lots of wild things nowadays people *can do*, but not a lot things people *will do*, because of time, money, ect. As an example, a wealthy government *could* create a city out of gold or chocolate, **but there would be no reason to do so *or* return on investment.** In this case, there will be no incentive for creating an artificial island because it would be ***extremely* expensive**; while on a natural island the people could mine and gather resources, rather than losing them. It would be beneficial to have an **abundance of islands** to this end, but even without this an artificial island made out of gathered resources would just be impractical. [Answer] ## Radiation or toxicity within a certain size range At size ranges above 100m, the particles start to become dangerous to life. In one variation on this idea they emit huge amounts of radiation with frequency that changes exponentially (or similar) with the size of the island. It's a sort of resonant cavity. Up to 100m, the emitted radiation is radio frequency, but above 100m you get into microwaves and everyone around gets cooked. Natural islands are so much bigger they emit safely in the visible light range. There may be continents that are borderline or completely uninhabitable due to UV/xrays/etc. Therefore, everything between 100 and 3000m is lethal. Collisions between carrier sized airships are always lethal and are a last resort of defeated admirals. [Answer] ## takes too long The crystals have to grow in place. This takes millennia but imbues the matrix they grow in with powers to hold them together. This is why the crystals break down when mined. [Answer] **Economics and ergonomics** There is lots of perfectly good land around the world to live on, yet people crowd urban areas. Why? Economics and ergonomics. Access to natural resources, industries, goods and services, jobs and opportunity are all reasons people choose to live on your natural islands rather than on new artificial islands. History plays a role as well: the natural islands have a great head start in terms of economical development, whereas making a new artificial island is expensive and seen as an insane risk, because no one would move to the middle of nowhere. Historically, frontiers were settled due to access to natural resources, but an artificial island doesn't have any of those benefits. Even if housing is very expensive on a natural island, it may still be more economical to build N additional houses on the natural island by towering up rather than build the artificial island + N additional houses. What about the lifestyle of living on an airship? Perhaps it's harder to sleep at night due to noise from engines or vibrations/rocking or even just routine acceleration. Perhaps people experience something like seasickness. Maybe people perceive it as being less safe. Would you live on an airplane? Probably not. And for many people, they would also prefer not to live on a ship or in a bus/car. Maybe people would feel life on an airship or artificial island would simply be less convenient in many ways. Other possible differences are the atmosphere and ambiance, air quality levels and pollution, presence of greenery and nature. It would take a lot to pull people away from their family/friends on the natural islands to go live on a barren artificial island. For the vast majority of people, they will not want to pay more for a worse life. There will always be intrepid explorers who are exceptions to the rule, and occupations which must to live on ships, but just like in our world, most people will naturally elect to live as they traditionally have if they can. [Answer] **It's too expensive.** Simply make these float-crystals very complex to extract. Specifically, I'd suggest something like "crystals instantly decompose into vapor when exposed to atmosphere" or "crystals immediately decompose when exposed to light". Both of these factors would make it superbly difficult to mine, yet allow them to function just fine underground and sealed away where they support the natural floating islands. For the airships, utilizing these crystals is still possible but they are difficult to acquire. Essentially, all the mining needs to be done in a vacuum, where the miners are sealed in the cave via airlock and need to wear tube-fed respirators while they mine. Then, once they find a crystal, they need to load it in an evacuated airtight container before it can leave the cavern. This means that small crystals for smaller flying ships are still possible, but building large scale floating islands is functionally impossible because you would need enormous vacuum containers to transport these island-scale crystals and this is simply so impractical compared the the comparative ease of transporting smaller crystals. [Answer] your magic particle have the annoying effect to repel each other. But in this case the effect become bigger the closer and the more they are. kind of like magnet but with a reach of several meters and the more particle in a given volume the stronger the effect. * A scientist studying those Natural Island will found those particle arrange in particular Cristal way in the ground. Way that defy comprehension and no one could recreate it. * One can make boat putting some of those in container. For larger ship the repel effect start to be feel and the container must be old tight with steel - concrete. No one can even imagine making a flying city. [Answer] They might be defeated simply by the logistics of the task, the unavailability of materials, and/or laws the inhabitants have developed against it. Presumably the floating islands are (mostly?) made out of ordinary rock/sand/soil? If so, then you'd have to deconstruct one in order to make more, since the surface doesn't offer anything. It could presumably destroy livelihoods, require a lot of (floating) earth-moving equipment, and might not really be to anyone's benefit. If you're after a more pseudo-physics kind of explanation, perhaps the force that keeps them aloft also keeps them intact, like a kind of extra, pseudo-gravity. So, if you created extra islands, they would tend to just run into and coalesce with existing ones. The existing ones don't do that with each other because they're far enough away and, over eons, have entered an equilibrium state. And the airships can of course be controlled. [Answer] # Increase the Gravity From what is written in your question, I take it that the island is supported by the thrust of your magic particles, and not by buoyancy of a gas. The pressure generated by the magic particles on these pistons causes these islands to float. Essentially, a zeppelin, without the buoyancy. There is an easy cheat code, that will prevent people from creating floating islands: **Intense Gravity**. Gravity always tends to mess things up. Have too much gravity, and you will struggle to lift things up, rockets become impossible etc. In your story, natural floating islands will have some sort of unknown mechanism, which would constantly renew the magic particles and thus, be able to remain afloat. However, since the inhabitants do not know this process, and never will, they cannot replicate this process, so they have no choice, but to constantly mine it from sources, to refuel themselves. Here comes the bummer. The planet is really massive and therefore has a strong gravity. Which means that the fuel gets depleted rather quickly, as the airship has to produce more and more thrust to get itself off the ground. For airships and flying carriers, this isn't an problem, as they are small enough to not fall back. But when you approach a critical mass, the amount of particles needed is too much to be possibly refueled in a reasonable amount of time, and thus the island falls back. That is the reason why people can float on airships and flying-carriers with the magic particles, but can never, ever get close enough to making real floating islands. [Answer] ### Ecology This is a twist on the *Not Enough Resources* answer. In this case, because the inhabitants can't go to the surface to mine crystals, every time they mined one from a floating island it would loose altitude. The result would be an impending ecological disaster, and laws could be passed limiting mining so that islands don't fall. As a result there would never be enough of the particles to float a new island. [Answer] ## They have to be monocrystals....and defective crystals are anti buoyant It's very hard to make giant monocrystals of anything even in real life. Natural islands have enormous ancient monocrystals that generate huge amounts of lift. Down on the planet surface, 99.99% of the crystals that form are non buoyant. They're actually antibuoyant, so much that they sink into the planet where they are heated and compressed. Once in a blue moon, a perfect large or giant monocrystal forms, large enough to rip up the soft earth above it and fly up into the sky. Smaller crystals can form at the surface without sinking or metamorphasising. They float around at various heights with no dirt on them. But best of luck making an island because: A) You can't combine two of them. At best, you break your nice boulder sized crystals into less buoyant crystals. B) If you make a mistake, the crystals become defective and become antibuoyant. Even a few defective antibuoyant nanoparticles are going to prevent any nucleation of good, buoyant crystals. They will seed anti buoyant crystals. This happens in real life to chemists trying to crystallise things, btw. In horror stories, crystallisation works for years until one day..WHOOPS! Time to move lab. What's worse, antibuoyant crystals grow really easily. [Answer] ## No dirt Remember Kevin Costner's Waterworld? In the opening scene, the hero gets mobbed because he has a pile of dirt. Now, I don't want your story to be like Waterworld in its reception, but maybe we can make lemonade from Mr Costner's lemon. Buoyant crystals are ten a penny. It's good old dirt that's invaluable. You can't grow trees on crystals, nor wheat. It constantly erodes and falls down to the surface and is only gained when a new natural island is formed. The amount of dirt you need to prevent a crystal taking off into the frozen stratosphere and freezing or choking everyone increases with the cube of the island radius. Economics forbids it. [Answer] It's not mentioned how long it takes for a natural floating island to form or how plentiful they are but since they never collide, it seems likely that they evolved a state of equilibrium over a long period of time equivalent to geologic timescales on Earth. **Cultural and Economic Barriers** The inhabitants of each island will have given each island its own name and cultural significance would likely be attached to each one. One thing that might prevent the construction of artificial islands would be chauvinism or snobbery, an unwillingness of the inhabitants to live on something as gauche as an artificial island. Still, considering that analogous projects on Earth managed to find buyers willing to live on man-made, aesthetically questionable coral reefs, we never know what people will go for, and a stronger case is necessary. The ability to create the first artificial airships would have marked a major milestone in the planetary culture's development, sparking off an era of exploration. And at some point, each floating island will be mapped, its orbital path characterized and relative mineral content classified, etc. **Lack of Raw Materials** Building an artificial island would represent a monumental task immense enough to consume the entirety of an island's resources for some time. The natural resources required to build it do not come from the planet's surface, since the inhabitants are isolated from that for reasons that weren't given, but the materials have to come from somewhere. They would have to mine something like planetary satellites or asteroids in the region, or destroy a natural island in order to produce an artificial one. This presents a very real logistic barrier, not to mention economic, to the construction of artificial islands, and it's a convincing one, I think. **Lack of Utility** But even assuming they could solve those issues, the OP mentioned that the buoyancy of the natural islands is dependent on a mechanism involving the solidified crystalline structure, which the inhabitants cannot reproduce artificially. In that case, there's really no question about what *prevents* them from building artificial islands. There simply is no benefit in doing so, and it's likely few people would ever seriously consider the possibility. **Planetary Forces** If, while the planet formed, the islands coalesced into their different altitudes and orbital paths from, say, an "accretion sphere" (which would actually be more like a series of concentric "accretion shells"), there may not even be any place to put an artificial island, since the reason there happens to be any space at all in the atmosphere that's not occupied by a natural island is because that space is part of a natural island's orbital path and was cleared out by spectacular collisions early in the planet's formation. Any early attempts to create an artificial island would place it right in the path of a natural island and it would be destroyed by the same processes that created the natural ones. **Biological Processes** If the inhabitants went on to develop technology allowing them to steer an immensely massive object out of the way of an oncoming land mass, they would still need to reproduce whatever ecological mechanisms exist to keep the natural islands perpetually inhabitable and able to continually convert metabolic wastes into to agricultural nutrients. Otherwise, life on the artificial island might quickly become intolerable (similar to the spectacular failure of the Biosphere 2 project in 1992, during which eight volunteers locked themselves in a 3-acre hermetically-sealed terrarium in Arizona which cost $150 million to construct. We should be careful, though, to note that the project suffered so much from bad administration, lack of expertise and mismanaged publicity that it probably failed even to falsify the validity of its own underlying concept.) [Answer] ## Lack of Structural Strength. Islands naturally float because more or less of the particles are dispersed through the rocky substrate that makes up a floating island. That makes the whole rock float, which tends to minimize stresses. If you instead pull it out and make a lifting cylinder, you have a large rock balanced on a single point. That has a strong tendency to crumble, with catastrophic results for anyone on it. Of course, you *could* carefully build a steel platform suspended by lift cylinders with a lot of lifting capacity, and pile dirt on it, but there is no compelling reason to do so. It's about like how we don't make artificial islands by putting sod on aircraft carriers: you totally could, but...why? [Answer] I can think of at least 3 ways. 1. They are too much of a target. A ship can always move but anything permanent just invites raiders who can approach from any angle. they can spend months planning waiting for the perfect opportunity because the target will always be there and you can't cover every angle of attack unlike forts on water or land. 2. proximity. You can't put too many of the cylinders too close together or something bad happens, they explode or attract dangerous wildlife, or they just start loosing power. which puts an upper limit on the size of thing you can float with it. That will not stop small outposts (essentially watch towers) but you will not get anything you could call a town. this either puts a limit on the size of ships or lets ships get around it by being light weight. 3. wildlife. the cylinders attract wildlife. Not a big issue for ships that is constantly moving but as soon as something is not moving for too long it starts becoming an issue. Either the wildlife is very dangerous or very destructive. sit still for too long and they start homing in on the spot is huge numbers. use anything from sky sharks to sky barnacles, to giant bees. [Answer] The Crystal structure required to maintain an Island is very specific, very large and vibrate at a frequency that maintains their 'pressure' upon the surface air, keeping them floating 'above', like an iceblock in water. they also give off reverberations, maintaining the frequency, and pushing them away from each other. To Create an Island, the inhabitants would need to understand the exact weight ratio of Crystal to Island size. They'd have to know the frequency for that ammount, get the frequency to be correct so their new island pushes gentle against all other islands and the planet itself. If any of these variables are wrong, the island would not sustain itself. None of this information is apparent in the crystal at any scale smaller than the smallest existing island. To study it, to break it in any way would possibly result in the very destruction of that 'chunk', and possibly you might have in your world history such an occurance. The Crystal 'mined' for your existing technology is from pre-existing veins that are identical but in far smaller chunks. They give off the same exact properties, and are far easier to access. All experiments on the smaller veins, have never resulted in hardening the crystal to the extent of making it a solid for longer than a day, and even when contained in a pressurized containment to maintain its solid state, It still is insufficient quantity to stabilise, harmonize and hold its state for longer than a day (or the desired maximum length for your plot requirements) The Initial formation of the crystal was aeons ago, when the world was forming, it was a complete sphere, and encompassed the world, metres thick, but it cracked, the islands you have now, rose from the original world, into their approximate places, the chunks that were too small, disintegrated and fell to the earth, creating mountain ranges (and veins of the material for plot hooks) *TL;DR: Only solid crystal is permanent, and its impossible to resolidify, and only singular large natural sized crystal will hold up an island, anything smaller (or groups of smaller) won't work. All sludge forms have a shelf life of a day and takes (plot required time) to recharge. Useful for an airship, useless for permanent floating cities.* ]
[Question] [ **Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49). Closed 1 year ago. [Improve this question](/posts/234377/edit) In my story a medieval civilization of elves is facing an invasion from a modern day earth power. They have prophetic powers, which have predicted the invasion will happen in ten years, and have that time to prepare. The earth power is similar to modern day Russia, with a similar airforce and mechanized infantry. The fantasy world power is an empire of elves who are part of a vast empire spread across an area the size of North America. The elves have technology similar to ours in the 1500s. Their magic grants them food generation power superior to modern day earth, so their population is similar to ours, at around 1 billion. They can also craft wood dwellings that are slightly tougher than native trees quickly, and train pets slightly better than modern day animal trainers can. From their prophesies, they know that the invasion is coming in ten years, that the invading power wants their vast untapped riches and wealth, isn't open to negotiation and is fine with genocide, and know about nuclear bombs, modern spying technology, poison gas, biological weapons, and the common weapons of doom. Portals of varying sizes will open at random locations across their land and invaders from the foreign land will spew out soon after. They are fine abandoning their cities if needed, and are politically unified enough to organize a huge amount of manual or violent labour to resist invasion. They have quick communication continent wide by horse back message posts. Airpower is a major issue. How would they best adapt their civilization to handle such an issue? That is the main question I am curious about. How would a fairly intelligent, coordinated, but vastly technologically inferior species try to mitigate airpower? An obvious basic answer is, attack them at their airbases, but that's obviously quite hard if it's surrounded by machine guns and artillery. Could they lure airplanes low enough to hit them with siege weapons? Could they damage them with smoke if they burnt a city the invaders were bombing? Could they defeat airbases better somehow? Better answers will explain how a medieval civilization could adapt use preparation time to reduce the power of airpower from a numerically inferior but technologically superior civilization. [Answer] Subterfuge and misdirection, dilution of targets. Build false villages all over the frikkin' place, abandon the cities and become nomadic. None of the villages is permanently unoccupied, but you move under cover of darkness, and live without night lights. As others have noted, you dig out so sleeping quarters are underground. Make the chances of an aircraft actually hitting a village with people in it about 1 in 10. During the day, camouflaged outlooks can signal villages *visually*, like using semaphore flags from over a mile away. (The earliest known record of a telescope on Earth was in 1608; it is not implausible that your medieval villagers have telescopes.) That's a speed of light communications system! Put them in pairs or triplets, they can alternate watching the skies and checking their telescopes for a neighbor signalling. The semaphore system can be adapted to send all sorts of messages, including counts of aircraft and compass direction. The elves will know what's coming long before it arrives, and be well away from the line of flight or deep underground when it does. The defense is hiding. It isn't invulnerability, but if you make aircraft so ineffective at causing death, it isn't worth the time and expense of flying them, and wasting expensive bombs on blasting empty villages. [Answer] Surrender With a modern military that is willing to commit genocide using nuclear, biological or chemical warfare there have no hope of mounting a serious defence. Bird strikes on planes and assassinations as in other answers will only provoke mass retaliations from the amoral invaders. Much better to just offer up when the invaders want in exchange for being left alone. If they want to strip mine a mountain to get minerals just let them, in fact work with them and try to learn the technologies. Maybe in a generation or two of being helpful enough civilians will be sympathetic to your cause that the military will be prevented from mass slaughter or you can learn enough of the invaders technology to meaningfully fight back. [Answer] A friend of mine once wrote a book on guerilla warfare. He found that in "asymmetrical warfare" situations -- where one side had what seemed overwhelming superiority in technology, equipment, etc -- the disadvantage side still won the war about 1/3 of the time. As someone else noted, we saw that in Afghanistan and Vietnam, and we're seeing it now in Ukraine. As an American, I might point out that the American Revolution was another example. The trick is to avoid open field combat. Yeah, an army with swords facing an army with machine guns on a wide open field on a clear day in two neat battle lines is going to get massacred. But a man with a knife jumping out of the shadows on a dark night and attacking a man with a machine gun has a pretty good chance of winning the encounter. You attack in ways that minimize the enemy's advantages. Sure, a medieval society isn't going to have any way to attack an airplane dropping bombs from 30,000 feet. But they could raid an airbase and attack planes on the ground. And they can make it hard for the aircraft to find them. In Vietnam, the Viet Cong hid id the jungles, where US aircraft couldn't see them. They couldn't bomb every square inch of the country. The US tried to destroy vegetation to reduce the cover -- that's what "Agent Orange" was all about -- but this wasn't particularly successful. In Afghanistan the mujaheddin hid from Soviet aircraft in caves. The disadvantaged force can try to capture weapons and turn them against their attackers. Or they can seek aid from nations hostile to the attackers who would be happy to see their mutual enemy stuck in a quagmire, with someone else doing the dying. [Answer] If your animal army extends to insects, they could be very effective damaging / sabotaging electronics. Swarms could confuse radar / infrared detection. If they have no compunction against suicidal birds, we all know how well aircraft fare against bird strikes. Or just even swarms of starlings dropping pebbles into the path of a strike aircraft would be a positive deterrent. Diving further into the animal kingdoms. If the invaders can weaponize CBRN forces, then is it within the elves power to fortify fungal or bacterial animalia to work against the invading force? Delivery of puffball mushrooms via small birds into the air conditioning systems of troop barracks could have some interesting effects, from outright death to mass hallucinations. Note, mass hallucinations within a heavily armed force is not ideal. [Answer] One way to oppose air force is to exploit landscape - planes aren't effective in mountains, as far as I know; jungles conceal all the people and buildings within it; extremely cold places may pose a problem for moderate climate oriented technics. Also there're some contraptions used in modern wars, requiring no modern technologies - e.g. camouflage and fake targets. I'm not sure if you'd allow elves to create ballons - they weren't available in the 1500s, but aren't really hard to construct; they may be used as obstacles for planes - though their utility is somewhat doubtful to me. Also dependence on fuel is a problem for invaders - it may be hard to transport lots of fuel through limited number of portals, to keep it safe at land bases, and to arrange its production in the new world; if the fuel in question is easy-to-burn oil, so much the worse. These tips make some preparatory actions quite obvious - cities in plains should be abandoned for ones in more defensible regions; camouflage, fake buildings and, may be, ballons should be developed and produced; the land near would-be portals should be prepared for defense and/or sneak attacks. It's really important if the elves can predict the portals location - they may be blocked by large rocks or flooded in advance. P.S. Naturally, these are ways to mitigate the problem, not to solve it completely. [Answer] In humans, prophecy is terribly inaccurate (especially as to *when*) and often actions can be taken to prevent the prophesied disaster. That offers a different hope for these elves. For example, the invading power can only invade if their political power holds together. So, the elves can spend the next ten years destabilizing the political base. Find the many disenchanted subgroups and encourage them to rise up against their political bosses. (That is what the Medes did to conquer the Asyrian empire.) Couple that with a propaganda campaign showing just how peaceful, kind, and nurturing the elves are. Show that living like the elves would make for a more fair and just society. Give the young generation of the invaders a different hope than just being cogs in their industrial machine and help them rebel against the system. This will help destabilize the political will to invade. [Answer] I'm going to assume that the invading power does not want to use nukes for some reason, because that would be game over pretty quickly. Even one tactical nuke in one place, with the threat of bigger ones unless the enemy gives up would be a devastating ultimatum. I'm also going to assume that the enemy isn't stupid (e.g. falls in the same trap twice). I would have them build as extensive underground networks as possible, making sure the entrances are hidden. If the cities are easy to defend, the enemy might make provisory bases in them, with a lot of defenses on the walls - but if you could have a small tactical band enter the bases through these secret tunnels, you cold have them sabotage equipment in a way that isn't directly obvious (therefore not alerting the enemy immediately), but that would prevent any tanks and/or planes to function properly in battle. Maybe they could even steal some automatic weapons? [Answer] **Bomb them right at the portals** The only bottleneck for the depicted invaders is the portals through which they arrive, and they cannot instantly bring in high-tech weapons that would be impervious to defenders, like aircraft, so this will be the major (or the only) opportunity to inflict enough damage to at least stall the invasion. Perhaps the offenders would be hurt seriously enough by such a greeting to reconsider risk vs reward in invading the elves. The scenario looks like this: You say elves have 10 years before the portals open, so they spend 8-9 of them to create as many catapults as possible, create enough ammo and locate them at the future sites of portals. One extra year is for planning, inventing, adjusting to the possibilities (say if they can grow catapults, why not? Same for ammo, up to making trees grow iron hard ready made orbs) etc. As soon as portals open, catapults start throwing stones, bricks, wood, tar, Greek fire, you name it, at the portal exit to do damage to the invading troops. Stones vs infantry, tar and fire vs armor which would be largely unaffected by the hail, but heating does cause armor to malfunction. At the very least the portal window would become obstructed to not let the invaders through. The downside is that the second attempt might start with the invaders stuffing an armed nuke into the portal prior to actual invasion, but you can handwave that either nukes would break the portals, up to all of them with a single nuke if it goes off close enough, or that fissile material in a nuke would not pass through the portal intact (say would undergo fission at once, setting off the bomb on their side, or just not reach critical mass on that side), rendering nukes unusable for this purpose, if you want elves to eventually win or draw. [Answer] **Logistical and cultural disaster.** * Your civilization lacks wide and load-bearing roads. * Nowhere to land aircraft or take-off later. * No petroleum fuel infrastructure for the invaders to capture and use. * Subtle incompatibilities of food and drinks. Most of them not deadly, but a lot of them at least temporarily incapacitating. * Developed culture of drug use that quickly catches on in the invading army. * Defenders quickly learning to use the invaders' technology [Answer] You can look at the Vietnam war or the Soviet invasion of Afghanistan for some real life examples, where a vastly more advanced air force didn't manage to crush the less advanced enemy. Avoid open field engagement and rely on guerrilla tactics, slowly bleeding out the enemy and affecting their morale. It helps if the territory allows "bite and run" attacks. [Answer] Plenty of good ideas in other answers, but they seem to be ignoring something I think is quite important: magic is a thing! Even a little magic can be a dangerous thing when you're not able to defend against it. Your elves have access to some magic, which you have said amounts to being able to increase crop yields. If this is the peak of their magical power, if they've never had more than that, then perhaps this answer isn't for you. If that's as far as they go simply because they don't need more, or because it was deemed too dangerous and was regulated into oblivion, then we've got 10 years to develop better options. Take the best of the agricultural mages, your top few thousand prodigies, and train them as hard as they can take. Focus them on uses of their magic that will help the most like rapid plant growth, plant manipulation and so on. Get them working in teams, pooling their power to work ever greater magics. Train them on using plants to disrupt infrastructure, mostly by doing what they do naturally just at a much higher speed. There aren't a lot of air forces in the world that can function effectively when their runways keep getting torn up by tree roots, or when grass and fungi decide that jet turbines are a perfect place to grow into. And you'd be amazed at how much mess the right strain of mold can make in an electronics bay. If you're lucky some of those planes might survive long enough for you to find a fungus that just can't get enough of the plastics used for wiring insulation. While that's happening, set your best animal trainers the task of learning the forgotten arts of beast mastery. Trust me, nobody wants to be on the wrong end of a charging dire bear or warg pack. But even that would be preferable to facing down a stampeding herd of aurochs. And don't forget that big birds beat back human armies in the Emu Wars. Twice. You don't even need to tame or control the beasts in most cases, just spook them and funnel the resultant carnage. Given that you have time to prepare, even magic isn't necessarily necessary to win this. If you have enough information to know to expect things like planes, rifles, IR/night vision gear and so on, you can plan for them. Elvish rangers are already known for their sneaky, so they're perfect for the guerilla role. They're trained to an accuracy that most modern snipers would envy, elvish arrows hit significantly harder than anything less than a .50-cal, and you probably don't want to know what a frangible metal arrowhead can do when fired into the intake of an active jet engine. It's really hard to get your plane in the air when your engines keep exploding during take-off. --- If you're interested in less magical solutions... The problem with bringing planes to a dimensional invasion is that they need a bunch of infrastructure in place before they can be useful. The invaders will have to send through a bunch of troops to secure a beach-head, followed by a group of engineers and equipment to lay out runways as quick as possible, and finally you can send through some planes. And hope that the locals give you enough time to get your infrastructure up. Which of course, you're not going to let them do. With 10 years to prepare you'll have time to set up detection and signalling to let you know when and where the invaders arrive. As soon as start to emerge you can rush in squads to harry them, making it much more difficult for them to establish the necessary infrastructure. Unless they manage to drive an aircraft carrier through one of those portals, the lack of infrastructure on the ground ends the threat of fighter jets before it gets started. The bigger problem is tanks. If you can fit a fighter jet through a portal then a T-90 should fit easily. You'd better train your siege engineers to hit moving targets. [Answer] # Near impossible to win You describe the difficulty of attacking planes. It'll be nearly impossible to attack them, as they can simply stay out of range. Even if they come into range they are so fast it'll be next to impossible to hit them. Even with animal pets they can be out if range. The first thing a helicopter or plane will do, if there's fldanger, is to fly too high for even birds to get them. With advancements in drones, access to mass destruction weapons including biological, chemical, gas and nuclear nothing is out if reach for the enemy. Even in bunkers underground the natives aren't safe. Reconnaissance drones can fly so high for so long that any native activities is detected except in a select few areas. The same staying power means you can rain down death and destruction for hours on end, out of range of the natives, until you're satisfied that everything is dead. ## flawed from the beginning Though it certainly isn't impossible to win for the natives, especially if they can leverage disease or some for of electronic counter, they are at an extreme disadvantage. All out open war will be quickly decided by weapons of mass destruction, making any superior numbers moot. Guerilla only works if you can hide. This would be within a population for example, but as the enemy will kill any population this is right out. There are precious few places where you can effectively hide naturally for guerilla tactics to work effectively. So only in a few areas this will work. That is if they don't just nuke the place, burn it down or gas it with heavier than air gas so even underground isn't safe. What will you do when a AC-130 flies overhead to destroy any specific targets while some rockets deploy a gas that'll burn the trees and kill anyone near? Pretty much nothing. What will you do when regiments of soldiers move through your woods with special optics, reconnaissance drones and an arsenal that can take out anything from a rat to a fortified bunker? Pretty much nothing. You might win some engagements, but to win consistently you need some real luck or incompetence from the attacking forces. [Answer] If you set up a scenario where one side has overwhelming advantages, you need to give the other side a win condition that partially negates the advantages, the means to attempt that win condition, and a motive to try going for that win condition against the odds. Star Wars makes a good model for this kind of story. The bad guys have all the apparent advantages. Darth Vader has a Death Star and a Star Destroyer and he's a powerful space wizard. The Rebels, however, have the secret plans, which gives them a fighting chance. In the third act, the Death Star is about to blow up the Rebel base, so it's do or die. Star Wars also does something else well in that there's a twist at the end that changes the game against the good guys: the secret plans *aren't actually good enough* to let the Rebels win. The twist is resolved by a thread that's been built up through the whole story: if Luke is willing to let go and use the Force, and if Han is willing to step up and embrace his calling as a hero, they can achieve their true potential. You've set up a scenario where in order to *try* to win, you have to bet a billion innocent lives and your *entire species* on preposterously long odds. In real life, the plucky underdogs almost always lose - *badly*. The obvious best solution here is to surrender and make it advantageous for the enemy to incorporate you into their empire as their loyal subjects, rather than slaughtering most of you and enslaving whatever's left - but let's get that off the table, since you want a story about plucky underdogs resisting technologically superior enemies. Maybe your elves are deeply religious and the Evil Empire prohibits all religion and is happy to genocide anyone who won't comply, and it's worth it to your society to roll the dice on genocide if the alternative is everyone going to Elf Hell for turning against the elf religion. Maybe there's a prophesy that the Evil Empire will bring about the end of both worlds if they get control of Elf magic. Whatever plot device you like: we just need to get the obvious best solution - surrender - *off the table*. Feigned surrender is probably the next best option, since it gives you a chance to get close enough to subvert some Evil Empire personnel and run your war effort like an organized crime ring. You'll want to think about whether you want your plot device to make that unworkable also. Once the solutions you don't like have been pushed off the table, you need to find a place to change the game so that the good guys have a fighting chance. Maybe they can make contact with another Earth power and set up a situation where Country A will nuke Country B if Country B genocides Elfland. (In exchange, Elfland promises lucrative resource extraction deals with Country A). Maybe the portals are being opened by an ancient enemy of Elfland who is living in the capital city of Evil Empire under heavy guard, but if only we can get to him and assassinate him, the portals will close forever. You have to figure something out, or the mechanical question of how Elfland might inflict occasional military losses on Evil Empire is *pointless*, because there's no connection between inflicting occasional losses and actually *winning*. [Answer] [Non-violent resistance](https://en.wikipedia.org/wiki/Nonviolent_resistance). When you can't win a fight, it's better to not fight at all. They would just let the invaders invade. But then frustrate any of their efforts to control and exploit the lands they just conquered through rigorous non-cooperation. They would also use political and personal activism to get the public of the invaders to oppose the invasion and convince individual members of the invading forces to defect. [Answer] Medieval era civilization cannot beat modern day army. We can produce bullets faster then they can reproduce. There are plenty of examples in out own history of such events - study colonization period. And that was before we improved our armies quite substantially. Don't forget - humans invented better firearms to beat other nations that also had firearms. Humans know how to beat melee army, elves do not know how to destroy tank (or how it works). I can see one big weakness in human invasion - the **portals**. Something opened them, something can close them. Without supplies, any army will fall sooner or latter. The Elves could train capable mages who will be able to infiltrate the portal sites and close them. Could create nice base for story :) Another alternative I can think of is **stronger magic**. Elves could spend the prep time training significant % of their population to use at least some level of magic. Everybody who can produce basic fire bolt can be infantry, who can create fireball will be anti-armour etc. Water mages can create fog cover to hide units. Any elven mass assault would still be suicide, but small independent units could be effective. [Answer] There's actually a well-known novel with a similar plotline: [The War of the Worlds](https://en.wikipedia.org/wiki/The_War_of_the_Worlds). In that book, the hyper-advanced Martians invade 19th century Earth, and devastate the foremost power of the time (the British Empire). But the Martians still lose the war anyway, because they have no resistance to Earth microbes. Something similar might work in your scenario. Hide, and use some kind of biological weapon which the invaders have not encountered but which the locals might already be largely-immune to (like smallpox). [Answer] ## Mud *and fog. and weather.* I put this as a comment on someone else's answer but the more I think about it the more I think it makes a good story element as well as a very realistic counter. If the elves have some magic capable of improving crop growth, then I'll assume they have something like weather mages that can keep crops from getting too much or too little rain. So when the invasion hits, the weather mages just keep directing rain at it. If they can do even more powerful storms, so much the better, but a nonstop drizzle of rain would be sufficient to drastically slow down even a modern army, because every army has a common enemy: mud. Mud stops tanks. Mud means your airfield needs to be paved. There are no "good days" to bring in supplies by truck or plane because the weather mages are keeping it raining all the time, everywhere the invaders go. Massed infantry churns up the ground and makes it increasingly more difficult for the rear to keep up with or supply the front. If the mages can manage fog, then even better, as this would do quite a lot to equalize any infantry battles as well as greatly diminish the effectiveness of air power. I actually think that between sufficient numbers of trained animals (which would drain ammo, at the very least) and mild but persistent and reliable weather effects, the invaders would have a really hard time getting anywhere. It would also surely impact the morale of the invaders. "I hate this planet. Why do we even want it? It never stops raining and everything is mud!" [Answer] The sheer scale of things works against the attackers. How many fighting soldiers, tanks and aircraft can a big, modern Earth country field at the same time? Maybe fifty thousand soldiers, 2000 tanks and 200 aircraft. Now compare that to your population size of 1 billion. That’s one soldier for every 20 000 natives. And this assumes that the attacker is actually willing and able to send their whole armed forces through portals and operate in a foreign world. Another scale thing: Size of the planet. We are talking about a huge area of land here. The attacker’s aircraft and vehicles probably can’t even reach many parts without significant effort (do aircraft carriers fit through your portals?). The scale of things is like a single well armed soldier with 300 bullets entering a town of 20000 people and trying to control it and hundreds of km² around it. Since your natives can create food and other necessities via magic they won’t have problems with supply and can easily flee and hide. ]
[Question] [ Plain and simple: could your offspring's offspring be genetically identical to you? What conditions would this be possible under, if any? [Answer] # Yes, but it'd never happen. There's nothing to prevent it, though the chances of it happening in the wild are effectively 0. From each grandparent you inherit 25% of your genes. Your parent inherits 50% and you get 50% of that. Some freakish coincidence could mean that you get the remaining identical 75% from your other ancestors and end up your own grandfather through misuse of time travel. # However This 25% rule is a useful lie, you get a random 50% of your parent's genes, you could get more than 25% from any grandparent, in theory you could1 get the full 50% from one grandparent meaning you only need to get the other 50% from the other side, excluding the risk of inbreeding. --- 1 A non-zero probability is a non-zero probability, you *could* also win the lottery every week for the rest of your life, it's non-zero. [Answer] You can, under these conditions: * you are a woman * you clone yourself and bear the cloned fetus in your womb * your daughter, when reaching sexual maturity, does the same. Your grandaughter will be a clone of your daughter who is also your clone. So the 3 of you have the same genes and are also related. [Answer] ### Linebreeding I am going to be bold and answer this question by cheating a little. I will assume that: * *Genetically identical* means "close enough", considering that it is not defined in the question. * You have more time than is available for a normal human (this is worldbuilding after all). * *Grandchild* is someone who is a child of your child (yes, we must point this out). [Linebreeding](https://en.wikipedia.org/wiki/Inbreeding#Linebreeding) can not give 100% equality but can get you arbitrary close given enough time. It works by breeding with your own children repeatedly, until you reach a satisfactory genetic closeness. Using the illustration from wikipedia, you are *S*, your initial partner is *D*, and your children and grandchildren are *DN:* [![Illustrating the family tree of linebreeding](https://i.stack.imgur.com/x3gg4.png)](https://i.stack.imgur.com/x3gg4.png) What happens is that you initially breed with *D*. Your child *D1* has 50% of your genes. Now you breed with *D1*. Your new child *D2* has 75% of your genes, and 25% of *D*'s. Again you breed with the latest child, and get a new child, *D3*, having 87.5% of your genes. **D3** will be your grandchild. It is *also* your child, but an individual can be both. You are D3's parent's (D2) parent. To calculate how close you get, you can use this function: $$f(g) = 100\*(1-2^{-g})$$ The tenth generation has 99.9% of your genes, and the twentieth generation shares 99.9999% of the genes with you. [Answer] In light of the answers from other people, I'd like to offer some basic math for how likely this is to occur. The scenario I'm considering is as follows: You, an ordinary human, have two children. Those children have a child together (yes, I know incest is bad - this is purely hypothetical). You, as an ordinary human, possess 46 chromosomes in 23 pairs. When you have a child, they receive one of each of these pairs from you (assuming nothing strange1 happens). As a side note, barring any medical breakthroughs that I'm not aware of, you would have to be genetically male (XY) so that your two offspring would be able to have children with each other. For simplicity, I'll call the set of chromosomes that your first child got from you 'set A' and those that your second child got from you 'set B'. In order for your grandchild to be an exact genetic duplicate of you, set B must contain all the chromosomes not found in set A, and then both children must pass on those specific chromosomes to their child. (This assumes that you do not have any chromosome pairs where both chromosomes are identical, which you probably don't unless you're the result of inbreeding). Now that we have established the scenario, let's talk about the probabilities: Let's assume the chance of someone's child receiving one specific chromosome from a pair is 1/2, as there are two possible outcomes. With 23 pairs, the likelihood of passing on any one combination is 1/(2^23) (roughly one in 8 million). In our scenario, we see this happening 3 times: you passed on set B to your second child, your first child passed on set A to your grandchild, and your second child passed on set B to your grandchild. 2 So, the likelihood that your grandchild would be a genetic duplicate of you is 1/(2^69), or roughly **one in 590 quintillion**. --- 1 By "nothing strange", I mean there are no errors in the replication of the chromosomes, and nothing along the lines of having 3 chromosomes of the same type, such as the case of [Triple X syndrome](https://en.wikipedia.org/wiki/Triple_X_syndrome), or anything else I haven't thought to list here. 2 If you're wondering why I don't count when you passed set A on to your first child, it's because there are actually 2^23 different set A's that are possible, so the math cancels out. This is based off the assumption that there is already some set A you passed on to your first child. [Answer] Is it possible? Yes. Is it likely? No. The only way to get an identical grandchild is if you have two children, one male and one female. Each of those children will get half of your DNA; in order to conserve 100% of your DNA, there can't be any overlap between their copies. They then need to have a child that combines the two half-copies into an original whole. The odds against this working out are pretty low. Humans have 23 chromosome pairs, for a total of 46 chromosomes. Each of your children has, under normal circumstances, one chromosome from each of these pairs selected at random. That gives a 1-in-8,388,608 chance of child "A" and child "B" getting non-overlapping copies of your DNA. Not too unlikely, as such things go. However, the same process applies to the grandchild: there's a 1-in-8,388,608 chance that the genetic contribution of each of its parents consists entirely of "your" DNA. Multiply that out for both parents, then multiply by the odds of the parents having the correct genetic makeup, and you get a 1-in-590,295,810,358,705,651,712 chance of the grandchild being genetically identical to you (give or take mutations). Yeah, not going to happen. [Answer] # Practically speaking: No Now, I'm not just talking about the absurd odds against it when going with the single-generation inbreeding method, the time it takes with the line breeding method, or the wild cost it would have if you use a gene editing based method. The fact of the matter is that we don't really have *one* set of genes; due to mutations, both deleterious and potentially intentional ones that happen at different rates throughout our bodies, we all have several very similar but still distinct genomes throughout our cells. Even if we use the most reasonable method of making a closely related grandchild (clone of a clone), we have to make a series of choices that will prevent us from making a perfect copy. First of all, from whence do we get our DNA template for our clone? A skin cell? A blood sample? A brain neuron? It matters, because they may well have different (although very similar) DNA. This choice has to be remade for the clone of a clone, compounding any errors. Second, how would we guarantee that each clone is subject to the same environmental stimuli and ionising radiation and viruses that can mess about with their DNA, and that they have the exact same number of cells in the exact same places to respond to these stimuli? The answer, of course, is that we can't. It might not even be *theoretically* possible. Finally, how would we ensure that the genetically identical clone *stays* genetically identical? Again, we can't. As I alluded to earlier, our body engages in an act of intentional messing about with our genome, specifically in our brain. Although the mechanism isn't completely understood, it appears as if memories are, in part, printed onto the genomes of brain cells, in addition to being stored in the network of neurons. This leaves brain cells with a lot more mutations than other cells in the body. In other words; if you're not genetically identical to yourself, how could you hope someone else to be? --- One exception: It can be done if you are a single-celled organism that reproduces quickly and asexually. [Answer] No. Even if you could have a "grandparent" and "grandchild" who were genetically identical, perhaps by two generations of cloning, they would not be the same person. Just as identical twins are not the same person. Of course you could, given the appropriate technology, have multiple generations of genetically identical clones. That's quite commonly done with plants. For instance, every plant of a particular rose variety is a clone of a single original plant. [Answer] Since copying of genetic material occurs with errors (mutations), whether you can get an identical copy even in the case of cloning (as mentioned above) depends on mutation rate. In DNA-based organisms like humans mutation rate for point mutations is about $10^{-10}$ per DNA base pair per cell division. Human genome is $3 \times 10^9$ base pairs. The number of cell divisions in the germline is about 20. Thus you get around 6 errors per each genome copied from grandmother to mother and another 6 from mother to daughter. The probability that you get an identical, mutation free genome is given by Poisson distribution and is about exp(-12) ~ $10^{-5}$, or one in a hundred thousands. Since humans are unable to produce such a large number of offspring, there is no chance to get an identical child or a grandchild. Actually we are rapidly degrading genetically as a species: Mutation and Human Exceptionalism: Our Future Genetic Load <http://www.genetics.org/content/202/3/869.full> [Answer] > > Could your grandchild be genetically identical to you? Plain and simple: could your offspring's offspring be genetically identical to you? What conditions would this be possible under, if any? > > > Sure, but it is unlikely. Suppose that the grandparent's ("your") ("GP's") genome has about 20,000 protein coding genes and that about 2,000 of these vary across the human population and (to oversimplify) that when a gene varies, there are two equally likely variations. To be genetically identical, the grandchild's ("GC's") genome has to match all 2,000 of the variable genes which, in this simplified model, has a 1:2^2,000 or 1:1e+600 likelihood if the matching is random and independent. But the matching is not random and independent because GP contributes on average 25% of the genes to GC so the likelihood increases by 2^500 (!) to 1:2^1,500 = 1:1+e450. If GC were the offspring of an incestuous relationship between GC's children, GP contributes on average 50% of the genes to GC so the likelihood increases by another 2^500 to 1:2^1,000 = 1:1+e300. If GC were the offspring of a disgustingly sick incestuous relationship between GP and GP's child, GP contributes on average 75% of the genes to GC so the likelihood increases by another 2^500 to 1:2^500 = 1:1+e150. Since the number of people alive is about 1+e10 and the number of people who have ever lived is probably at most 1+e12, the likelihood of a 1:1+e150 occurrence in 1+e12 events is materially zero. [Answer] Someone could arrange for that to happen in a way that would be sort of a cheating method. 1) It is certainly possible for someone's grandchild to have by chance the exact same genetic code; but the odds against that ever happening are astronomical. 2) Therefor some medical way to ensure that someone has a grandchild with their exact genetic code would be needed. Someone could clone themselves and have their daughter serve as a surrogate mother for the clone. Thus when the clone was born it would be the (nongenetic) child of their daughter and thus their grandchild. That seems like using a loose and somewhat cheating definition of grandchild but it is something that it might be possible for medical science to achieve only decades in the future. ]
[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 6 years ago. [Improve this question](/posts/97642/edit) A group of scientists (in my idea for a novel) have secretly invented an invention with which every person on this planet can be turned to behave altruistically. In the context of my question the term "altruism" means "concern for the welfare of others". Since this would be an ideal world if everyone were friendly, considerate, and helpful towards everyone else, I cannot for the life of me come up with an antagonist (or several) who would oppose the plan to make use of that invention. Probably certain rich folk would prefer to not want to give away their wealth, and [some individuals might resent the idea that they were no longer acting of their own free will](https://en.wikipedia.org/wiki/The_Giving_Plague), but I don't see these individuals acting on their unease, and I don't see any sane and thinking person *not* wanting altruism for everyone. I guess I'm blinded by my own ideology, so: **Who would oppose a conspiracy to turn everyone into altruists?** I'm not looking for mere objection, but for someone who would put themselves in the way of those who want to turn everyone into altruists and take measures to wipe out that "threat". Would a government send their secret service? That kind of opposition. --- Since there has been some misunderstanding about this point, let me reiterate that the phrase "every person" in the first sentence of my question indeed means every person, including future generations, and that "every person" according to the dictionary definition of "every" includes each man and woman without exception. --- *One objection has come up several times, so I'll address it here:* Being altruistic does *not* imply that * you force help on someone who does not want that help * you disregard individual differences and help everyone in the same way * you know what is best Of course, altruists will * have to ask a person what they need and whether they want help at all * make mistakes and unintentionally cause suffering * have to face difficult decisions To make the premise more clear: **The device removes any inclination to intentionally hurt others and makes everyone consider the wellbeing of others before they act.** It does not make anyone lose their self-preservation instinct or make them stupid. [Answer] You are going to change everyone on the planet. How did they test that invention in the long term? And by long term I mean people affected by this invention will be able to become parents and their kids will be normal healthy individuals. You are going to change brain processes, how do you know this would not end like some sort of [prion](https://en.wikipedia.org/wiki/Prion) desease? So there are strong health issues that does not seem to be tested. Then you have privacy point of view. You are affecting someone without his consent! [Answer] "We are going to use a machine to change your personality whether you want it or not. We're only going to use it one time for one innocuous purpose. Honest! 'Zat okay with you? Not like it matters if you disagree..." Here's the issue ... **how can you trust these scientists**? Short answer: you can't. You can't possibly imagine that after using the machine once they'd destroy it utterly. That they might have ... other things they'd like to change. Maybe these scientists favor free-market economics. Maybe they want extreme population reduction to lessen the ecological impact of humanity. Maybe they are all Bahaists. Etc. They have the power to change your brain to want what they want. This is a ghastly power. Let me put it to you like this... would it make a difference to you if this machine were owned by Ayatollah Ali Khamenei, Pope Francis, or Vladimir Putin? If it makes a difference, then you see why these scientists **must** be slain. Instantly. In fact, **anyone** who doesn't already agree with the scientists *on all possible points* will want to oppose them. Every covert operations group *on the planet* will be gunning for these guys. The grouchy old coot who lives down the road and loves to shoot stopsigns with buckshot will be gunning for those guys. Surprisingly, *graffiti artists* will lead the hunt to destroy the scientists. (An altruist wouldn't deface someone else's property, right?) Actually, the scientists themselves should realize this. They know that whoever controls the machine controls every soul on the planet. I suspect that at least one of them will have a crisis of confidence and try to destroy the machine. And at least one of them has a more ... aggressive agenda. This would make for one humdinger of a story, but any sane person would gun those dogs down on sight. > > Update: Just to make it real clear ... I'm not criticizing 58980's story idea, I think it will be a fun tale, but I do want to point out that I reckon there'd be huge, immediate opposition to The Plan. > > > [Answer] > > Who would oppose a conspiracy to turn everyone into altruists? > > > I think you already answered this with the most obvious group who would oppose such a thing... **Anyone who does not like the idea of having their personality changed against their will or without their permission.** Or as I would call them, "basically every human being on the planet". For some reason you dismiss this as just 'some people'. But I suspect it would not be some, but rather the large majority of people who would oppose it (if done without people's permission). Also, on a more philosophical level, you say this device turns everyone altruistic. But is it really altruistic to deprive people of their free will by choosing for them that they will undergo this transition? I'm guessing no. I suspect most people will find the very concept abhorrent. One thing to keep in mind: I hope your process can 'convert' the entire planet at once, because if it doesn't, those who aren't yet altruistic will be able to take great advantage of those who are. [Answer] I think you have highlighted the people yourself. Those who already have the most stand to lose the most so might not be so keen. It would depend on how much they had relative to the others. Extreme differences might present greater opposition. It would also depend on the total amount of resources available. If everyone is on the breadline and a few are just about it they will not want to lose their advantage, whereas if everyone is relatively wealthy then the effect might be less intense. You are also correct to assume there will be people who will resent loss of freedom or privilege such as philosophers, priests or anyone in a position of power or who worked for the police for example. Who actually decided to oppose the change would depend on the type of altruism that you had in mind and how the population were informed (or misinformed) of it. It sounds wonderful if everyone is an altruist, but even an altruist needs some rules to work by and not all rules are created equal or considered to be equal by everyone. As an example consider utilitarianism as the basis for your altruist – the greatest good to the greatest number. Sounds fine in principle and in many cases it is an excellent way of dividing up resources or deciding what to do but it does have some terrible flaws if taken in isolation. Imagine five people about to die in hospital. One needs a heart transplant, another a kidney, another a lung etc. In walks some health visitor to give blood. It just so turns out that he is a perfect match for these five people. So the hospital authorities weigh up what to do using utilitarianism and their decision is that the needs of the five outweigh the needs of the one so the one visitor must die so that five may live. This is just one example. Whatever system of rules, morality and “altruism” you adopt there will always be corner cases and difficult decisions to be made. [Answer] complete altruism is not necessarily a positive trait. If it was (and egoism was negative) natural selection would have already wiped it out. To back this up, consider that some year ago (citation neeeded, but I cannot remember it after 25+ years) some scientists did a simulation: a population with various expression of heroism gene (-- coward, -+ fairly brave, ++ heroic to death) was attacked by reckless enemies. Cowards and fairly brave escaped while the heroes were fighting until their life. This behavior saved a part of the population and, more importantly, the gene for heroism. A similar reasoning can be applied to altruism: in certain situation altruism is not an advantage (imagine food scarcity: an egoist not sharing his scarce portion of meal with someone else will survive, while sharing it will lead both to death). On top of this you have also to consider ethic opposition related to the lack of free will. So, I suspect opposition would come from a fair share of scientists and philosophers. And rich people would surely support them. [Answer] This sounds like a principle I've observed and lived by for a long time... There's a huge flaw with the concept of "treat others the way you want to be treated." The flaw is: Not everyone wants to be treated like you! So it is with altruism. One person's altruist, would be another person's nemesis. This would end up going very, very badly. In fact that seems like a perfectly reasonable resolution of the plot... the basic realization that everyone is different and unique and it's simply not possible for everyone to be altruistic, because everyone has different definitions of altruism and you'll never have everyone in agreement. [Answer] I've only somewhat skimmed some of the answers, but here's a take that looks to be somewhat different than what has already been suggested: what if you had a group of highly religious individuals who had an issue with this because it is changing the way God made someone (according to Catholicism, God makes everyone unique, with their own talents and ways of going about helping others -- if this was artificially homogenized, they would definitely have a problem with it). If our current world is any indication, their disapproval would go beyond simple unease and would advance to action. I think this would made your story more interesting and dynamic, and you could have a lot of interesting themes and messages going on throughout. [Answer] [Liberals](https://en.wikipedia.org/wiki/Liberalism) - at least in a sense of movement coming from Enlightenment not any political party in any particular country. Liberalism is based on the principles of individual freedom and ability to decide for themselves. Forcefully brainwashing population - even with 'good intentions' - seems to be antithesis to the liberalism not much better than controlling them by state religion (separation of state and religion was one of the postulates of the Liberals). I don't think you can call yourself liberal - be it 'classical liberal' or 'liberal socialist' - if you aren't terrified by someone considering to rewire the brains of whole population. Also depending on the scope and exact details - economists. The economy depends on the people making rational choices to the extent they have information. By definition I have a better image of what I want than you do so if you give me a present it might cost you more than it's worth for me (setting aside values of the social relationship). That's not usually a problem as such exchanges are small portion of exchange but it might collapse the whole system if majority of transactions start to be wasteful and any hope of planning goes away once the [price discovery mechanism](https://en.wikipedia.org/wiki/Economic_calculation_problem) goes away possibly resulting in massive starvation - hardly an aim scientists aimed for. If the effect is very strong you need to somehow find out how to solve [basic economic problem](https://en.wikipedia.org/wiki/Economic_problem). There's lot of resources from both side (at least century or so of debate) so I'll leave it at that as I'm no economist (though most of the debate assumes that humans are at least partially self interested. It might be a bumpy ride though as economy transforms and reshapes). (To preemptively clarify: I like the idea, I'd be terrified of both such project and consequences) [Answer] There is a nefarious group of people who have heard of this project and they are going to spend A-day underground, in quadruple-layered Faraday cages with their tinfoil hats in place. Afterwards, they will be the only greedy people on the planet and they will RULE it. The heroes have heard of this and decided that they are unable to penetrate the villains compound, with the mine fields and all. However, the security around the mind control ray is lighter and easier to breech. So, to stop the villains from gaining control of the planet, they must stop the mind control project. [Answer] There exists a very long lived and very well known conspiracy to turn people into altruists. For example [Matthew 19:21](http://biblehub.com/matthew/19-21.htm): If thou wilt be perfect, go and sell that thou hast, and give to the poor, and thou shalt have treasure in heaven: and come and follow me. [Mark 12:31](http://biblehub.com/mark/12-31.htm): Thou shalt love thy neighbour as thyself. And the best of all: [Matthew 7:12](http://biblehub.com/matthew/7-12.htm) And as ye would that men should do to you, do ye also to them likewise. How can anyone oppose that? Yet many people have opposed this conspiracy, and the most successful people have done it from the inside: embraced the premise of the consipracy (because who could possibly oppose such a thing) and then diverted the energy and enthusiasm behind it to their own ends. There are people who, in the name of this conspiracy, advocate and themselves practice hatred, the killing of persons who behave in certain ways, and the accumulation of fabulous wealth. Such persons find it more effective to instead subvert the conspiracy and turn it into something different. What better way to oppose a thing than to turn it into its opposite? And then, unfortunately, those people who overtly oppose a conspiracy that we should all be good and love one another do so because the first group has ruined what it was supposed to be about. [Answer] **"It's for your own good" has been so overused that it's discredited.** Postwar history is full of inventions which were supposed to be of universal benefit that have developed unexpected downsides or flaws. People have started distrusting everything, including supporting evidence. *Vaccines* are altruism that people have started opposing. So I would say that there are very definitely going to be people who disbelieve the altruism in your scheme and oppose it on that basis. **What is altruism, anyway** Does this extend to other species on the planet? Is it altruistic to forgo consuming resources in order to benefit them? Therefore, is it altruistic to never have children in order to deliberately bring about the extinction of the human species? [There are people who already believe this.](http://www.vhemt.org/) Therefore your "universal altruism machine" might bring about the extinction of humans. Are you sure this is a good idea? [Answer] Who: As other said Libertarians, evolutionary genetics and economists. So combine these group into one character (and you have perfect leader for oposition). Why would they fight it even at cost of their life? They/he was already influenced by this invention, they know that it is bad (on surface it sounds good, but they know it's bad for everyone) and they already are altruistic, so they are willing to sacrifice themselves. [Answer] I would. The problem with altruism is that it relies on everyone instinctively knowing what is good for others. How can they possibly know that in all circumstances? My life is complicated enough, without having others actively deciding what is best for me. I might not agree. I might not agree for altruistic reasons (but my reasons, not someone else's). Where does the standard 'altruism' come from in the end? [Answer] # I would be against it. This is basically the premise of the film *A Clock-Work Orange*. A few thoughts Firstly, why do you think that scientist are especially able to define what altruism is, why do you think there definition of altruism should count above everyone else's, this shows a clear bias on your side.I'm assuming the scientist who decides altruism is not called Mengele or Kevorkian Secondly, the removal of free will is not a noble cause. Without free will a person is basically a slave, do you think making a slave of all of humanity is noble, remember slavery and love does not mix. > > Since this would be an ideal world if everyone were friendly, > considerate, and helpful towards everyone else... > > > This may be your ideal world but my ideal world will tolerate some rude people so as to ensure that everyone has the free will to choose there rudeness because of there own free will. What makes your ideals more worthy of enforcing on all of humanity than mine? [Answer] Dystopian SF mode: The scientists would test their invention on at least a few people before using it on everyone. If successful, this would create a group of perfect altruists, people who really want the best for humankind. Therefore, the first thing these people would do would be to realize this invention is pure evil, and thus murder the scientists, and destroy the invention itself and all traces of its existence. Before doing that, for a bit of extra fun, they could fight to the death among themselves: being perfect altruists, they would value the good of the many versus the good of the few (including themselves and their buddies). They would all agree that everyone should give everything they have above a certain level of wealth to a Good Cause... However their opinions about which cause deserves the most resources would differ. What's a few dead dissenters when you're working for the Greater Good? We can only hope the survivors get a "what have we done" moment and decide it wasn't such a good idea after all. [Answer] Q: Who would oppose a conspiracy to turn everyone into altruists? A: Any lLibertarian\* that I know :-). lLibertarians are all for liberty but opposed to coercion - even if the intent is to coerce them to do things that they would voluntarily do. Llibertarians tend to be opposed or very opposed or radically foaming at the mouth vehemently opposed to anything that includes even a mere smere whiff of "Socialism" [tm]. Your proposal does, so they hate it with a pure shining unquenchable hatred. **\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_** \*I use the term lLibertarian or Llibertarian as they can be very picky about whether they are called a libertarian or a Libertarian. The former is an individual with this bent, and the latter is a formal member of a lLibertarian organisation, I'm told, I think. ]
[Question] [ I'm workshopping a medieval fantasy setting and one of the primary locations is a large port city, located on a bay out to the ocean. I'm still early in development, but since this settlement is quite large and located relatively close to borders with another country, I'm working out its defenses, the big one being its defensive walls. Among the details I'm a bit stuck on for the walls, is the towers. Specifically, how spaced out they should be. Obviously nothing's a perfect square or circle, but is there a general estimate on how spaced out the towers should be, relative to the estimated length of the wall? [Answer] The spacing of [towers](https://en.wikipedia.org/wiki/Fortified_tower) along medieval [curtain walls](https://en.wikipedia.org/wiki/Curtain_wall_(fortification)) was typically to provide [flanking](https://en.wikipedia.org/wiki/Flanking_tower) fire along straight sections of wall. In order to provide proper flanking fire, it would be necessary to situate these towers a distance apart that is less than or approximately equal to the effective range of the missile weapons in use at the time at which the fortifications were built. The OP would have to decide what missile weapons are in use and what their effective ranges were. For example, longbows had an effective range of up to 250 metres against massed enemies, and crossbows had an effective range of 100m. The towers would be spaced accordingly so that troops on one tower could shoot enemies at the base of a neighbouring tower. Of course, closer spacing would allow more accurate missile fire against enemies. As pointed out in comments, walls that are not easily approchable may have few, if any, towers for flanking fire. Such towers were primarily built on easily approchable sections of wall. [Answer] **From 30 to 150 meters, but 60 meters or less seems to be often preffered in big cities** The citadel of medieval city of Carcasone has wall in length of 3km with 52 towers, which would give you the average distance of around 60 meters, during the Roman times the spacing between the towers of castellum were between 18 to 30 meters. 14th century fortification of Vyšehrad in Prague had 15 square towers spaced 60 meters apart plus two fortified gatehouses. Wall of Philip II Augustus in Paris built between 1190 and 1213 had 77 circular towers in 60 meters intervals. Wall was considerd adequate long into 15th century. Forification of Brussels in 14th century was 4km long and had 40 towers and 7 fortified gatehouses, that gives an average of 85 meters. Of the walls of Tallinn built in 12th century there is 1850 meters still standing today with 26 towers, that is average span of some 70 meters. Based on tourist information a wall in Rothenburg has 4 kilometers and 42 towers, which would give an average interval somewhere under 100 meters. City of Krakau was fortified in 13th century by 2km of wall with 50 towers and 8 gatehouses - average of 40 meters. City of Citadella has its walls built in 13th century in total lenght of 1461 meters and has 32 towers evenly spaced at around 45 meters. Based on those examples I dare to say that in medieval Europe, if city was sufficiently wealthy it aimed to one tower at least every 60 meters. You can browse the [List of walled cities](https://en.wikipedia.org/wiki/List_of_cities_with_defensive_walls) for more inspiration. (beware not all listed has medieval fortifications) [Answer] In addition to @MontyWild's excellent answer, consider the practicalities, too. * Your city/town doesn't have an infinite amount of money or resources. That means that, while the ideal would be to space them such that a ranged weapon could hit the next tower in either direction, there's a good chance you can't afford to build or maintain that many. That means you need to think through placement of the towers using other considerations like the terrain outside the town and what's inside the town (e.g., how easily an area could be accessed if the wall is breached or whether or not what's in that area deserves special protection or could be used to your advantage if the wall is breached). * Your city also doesn't have an infinite number of people to man those towers. At least one defender per tower. Probably more. In shifts. They all need to be fed and supplied. That really adds up (see bullet #1) and your town might not have that many people to spare. * Towers are often a function of the wall's engineering and not a function of the wall's defense. Some medieval walls had ramparts, meaning the towers themselves weren't that important in terms of defense. What they really were, were places where the rest of the wall could anchor. Corners, places along long lengths. Either side of gates, etc. In this case, defenders are firing ranged weapons from any location along the rampart and the towers, if they have any meaning to the defenders at all, are simply a nice place to store supplies or stack the ~~dead~~ wounded. * You don't tell us whether the walls are made of wood, dirt, or stone. Medieval walls were made from all three basic resources. If you *really simplify* history, you'll find mounded dirt first, wood bulwarks second, and stone third. You won't have towers with mounded dirt. You didn't see a lot of towers with wood, but when you did, they were always at critical structural points. It's the stone walls where you might see towers placed purely for defensive purposes. What all those bullets are telling you is that you need to view a bigger picture than just defense. In fact, I suspect that if you look at real medieval wall design, you'll find that nearly all towers served structural purposes before they served defensive purposes. In summary: * Where do you need towers to make your wall structurally sound? * How much money/resources do you have to spend constructing and maintaining towers? * How many defenders can you really supply to staff all those towers? [Answer] The Great Wall of China spaced its watchtowers anywhere from three miles to over double that depending on terrain. Work out what the towers are for and then space them appropriately. If the wall itself is your primary fighting platform, then the towers don't need to be close together. If the towers are more important fighting platforms then you need them within bowshot of each other at the very least so they can support each other. With long border type walls towers are mostly for housing the defenders and storing ammo and supplies, perhaps some artillery. The wall itself would be taken before anyone bothered attacking the towers. They're expensive to build and maintain and of limited value. If you have unlimited resources then Byzantium would be another option. It was a fully fortified port city with towers about 60 metres apart which could support each other. It withstood sieges repeatedly and some armies just looked at the fortifications and turned around and went home again. But this level of protection was only possible because it had the resources of an empire behind its building. [Answer] If the wall is round, ever expanding peripherary needs more towers per unit of length. Draw a circle with scale radius. Bigger your settlement the more towers you need. [![enter image description here](https://i.stack.imgur.com/VO1Cn.png)](https://i.stack.imgur.com/VO1Cn.png) Generally, there are no rules regarding the overall distance between towers of a castle or fortified city. Towers were put in the walls at a necessary point, so guards would have a good view on the surroundings. If it's one person per tower, best case scenario is One tower every 100 feet. According to Guinness World Records. The normal intelligible conversation via outdoor range of the adult male human voice in still air is 180 m (590 ft 6.6 in). For defense that's long. Another strategy is have NO towers except at points of entry like gates. And have a battlement fully walkable by personnel. But hidden behind wall so guards cannot be seen. [![enter image description here](https://i.stack.imgur.com/k5ybe.png)](https://i.stack.imgur.com/k5ybe.png) [Answer] Tower + Archer Radius intersects with Tower+ ArcherRadius. Point of intersection distance to wall is within half-archer distance from wall? ]
[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/184703/edit). Closed 3 years ago. [Improve this question](/posts/184703/edit) Let's assume we have this super advanced civilization that actually goes around making Dyson spheres around stars. The purpose of this is to capture all the energy of the star and be a hub of the system in shipbuilding, weapon building, administration, and military matters. Think the Citadel from Mass Effect. All this free energy is being used to power shields and weapons. If you had a civilization with such technology and such a station, with a near limitless power source, would the station be invincible? We see in fiction how shields can be overpowered by constant bombardment. But if you have the sun as your power source, would it be possible to ever break the shields? The station would also have incredibly powerful weapons, given its power source. I understand that it's not a matter of pure power, but let's assume that the civilization has incredibly sophisticated shields and weapons, and all they need is the power to power them up. Assume incredible overall technological ability to the point that their shields can be attacked for months without failing and their cannons,an constantly fire. Would that mean their stations would be invincible? In the context of galactic empires fighting, Dyson Sphere stations seem like they are checkmate. They have a sun and unless you teleport to the system with your own sun you are not breaking through. I'm no scientist and so the finer points of science would be very handy here. And I'm not looking to hand wave the whole thing by saying: their science is so advanced. At the same time I'm not interested in limiting this advanced universe to 2020 abilities and understanding. One thing I've considered is that maybe it is simply impossible to translate the raw power of the sun to raw power for the station, or a time delay / technological obstacle preventing instantaneous transition of power to the shields and, to a lesser extent, weapons. Is that the case? What are other potential problems with these invincible stations? [Answer] **The Problem of Defense:** This is a similar problem to the one envisioned by the French after WW1. They imagined the Maginot line would make France invulnerable to attack, but the Germans simply side-stepped the defense, or, as in the case of the Belgian forts, they simply sabotaged them or used bigger explosives. There is always a struggle between defense and offense. While I agree that the Dyson sphere defense is probably invulnerable to lesser civilizations, any of their peers will simply apply engineering until they come up with a way to overcome it. While a Dyson sphere is an amazing feat of engineering, it is still a gigantic passive power collector. So you use a Dyson sphere to power your station. Your "Invaders" threatening your "Spherians" arrive with a fleet to attack the thing. The Invaders have planet-sized ships and antimatter-powered cannons. Your Dyson sphere is putting out a huge total amount of power, but it's still a giant collector for a known and fixed quantity of output - one star. When one ultra-powered race confronts another ultra-powered race, the conflict is using ultra weapons and ultra power sources. The Invaders can have hundreds of planet-sized attack ships and still not use up as much mass as the Spherians did building the sphere. the attackers can keep bringing more firepower to compensate until they exceed the defensive ability of the sphere. The sphere is fixed and cannot move away if the enemy has too many ships. Further, because of the vast size of the sphere, it makes a HUGE target. The smallest sphere is as big as a star, assuming you're okay with the inside surface not being a habitable area. Shields protecting it need to be correspondingly vast. The Invader ships can be powered by devices that put out more power per unit of size - probably a lot more power, if they don't simply stream vast quantities of antimatter AT the sphere as an attack. Your Dyson sphere is more a city or a factory and less a battleship. Cities can have walls, but no walled city is invulnerable. There's always a bigger cannon. [Answer] **Invincible?** We honestly have no idea how closely a dysonsphere/swarm/blah could be built to a star. Future tech would suggest that it could be built as close as wanting... but that doesn't change a couple of issues. That's a LOT of surface area to protect. As intoned by the great George S. Patton: "Fixed fortifications are monuments to man’s stupidity. If mountain ranges and oceans can be overcome, anything made by man can be overcome." You might have a near limitless amount of energy to work with compared to *Ming the Merciless' Amassed Armada,* but while you're filling the solar system with the future equivalent of hot lead hoping to hit those little itty-bitty ships, he's dropping a thunderous number of bombs on that massive shell. To be fair, I'm having trouble finding a reference to the sun's total output and not just the amount of output experienced by the Earth. For example, [this reference](https://ag.tennessee.edu/solar/Pages/What%20Is%20Solar%20Energy/Sun%27s%20Energy.aspx) suggests 3.846×1026 watts... but goes on to ask something akin to "how can the Earth survive?" which leads me to wonder if that's all the energy released from the surface of the entire sphere, or just the portion we experience. But, to be honest, if that portion that reaches Earth is only equivalent of 696 TW over ground the size of Texas... maybe we can fudge it and assume that said number is the best you're going to get anywhere on your dysonsphere surface. So that's the maximum you have to work with (estimatedly speaking). And the entire Texas-sized chunk of surface must be defended with it. And machinery run with it, etc. Now, to be fair, unless Ming's fleet is gi-honking-normous, then an awful lot of energy batteries can be brought to bear. But that would be foolish. Energy weapons have effective ranges because there are limits to how well the optics (even if run with Clarkean magic-driven gravimetric fields) can focus and how far the energy can go before it begins to dissipate. So what would Ming do? [He drags mines](https://youtu.be/R9eAD2wXi-Q?t=189), or the inexpensive equivalent. Nobody it going to attack a dysonsphere unless they think they have the technical capacity (or the foolish arrogance) to actually punch a hole in it. So Ming has the same gravity-based mass-collection system used by the Sphere builders to capture and haul mass to the construction site — only he's using it to drag asteroids. Bazillions of asteroids. And he doesn't really have to punch a hole in your sphere. He just needs to *shift it.* And your defenses can't just break up the asteroids, they have to atomize them! Otherwise the mass will still hit your gravity-heavy sphere (which works in Ming's favor). Push it off center just a little bit, and you're hosed because you suddenly have to dump tons of that energy you were using on defense to push your sphere back on center. Stars are just a bit uncaring, dontchaknow! So, frankly, I think that "invincible" really only applies where there's a serious technological difference between attacker and defender. If they're on par, it's just like any other siege — *desperate.* [Answer] Assuming I am a war-hungry civilisation, of equal or slightly greater tech your Dyson Sphere loving society, how would I destroy you in a frontal attack? 1. Find or create a small black hole. 2. [Blackholes move towards mass](https://en.wikipedia.org/wiki/Binary_black_hole), and behave as any other mass for orbital calculations, so have big, massive, ship nearby, both will be drawn towards each other. The black-hole will be very mobile, cause it's small. You want about 100 kg total mass. Too light and it'll come to you for hugs immediately upon creation. Too heavy and it'll be too hard to move. 3. Thrust the ship away from the blackhole, towards the enemy Dyson Sphere. The blackhole will follow (as it's attracted to mass) 4. When you start getting close to weapons range to the Dyson Sphere, accelerate something heavy back into the hole away from the Dyson Sphere, floor it and then GTFO. 5. Black hole consumes the mass you released, grows (making it much harder to change direction now), absorbs the momentum (so it doesn't overshoot the system), homes in on the Dyson Sphere mass, and collides with the Dyson Sphere. Now this is borderline ridiculous, I think it'll work if you really want to do it, but there are ways to bring down a society without firing a shot, and a realistic military strategy wont attack an enemy at their strongest point. Attack their transport / trade ships going between, set up barriers between spheres to stop them communicating, or hack their communications. Create rumors about the leadership. Spawn a religion that undermines their values. Give them a virus (computer or Covid). [Answer] **Subterfuge** Let's assume you have the power of a star and can harness it with near perfection. In nearly all cases it's not possible to have a higher energy density within a solar system. The energy output is so high, that not even the whole astroid fields in our solar system have the energy to compare. Depending on how your cannons and shields work, they can vaporise or deflect anything short of a planet before it even became a threat. So you would basically need to hurl a planet, which isn't an insignificant feat, to even have enough energy to move the Dyson sphere a fraction. But any engineer would add something so it would be able to correct it self. So possibly the sphere would be invincible. *except that it's not*\* The invincible object has been done often in fiction. Let's look at a famous example, the 2nd Death Star. I'm taking the second one, as I'm assuming not even small fighters can come close to a Dyson Sphere civilization. Computers would make calculating trajectories and blowing stuff up a piece of cake. What you need is *subterfuge*. This can happen in many ways. Hacking the structure would be a great start. Although you can assume the computers are compartmentalised so you can't take over the whole structure easily, even taking over one part can be catastrophic. Redirecting the energy can lead to structural failure or possibly authorising a force to get onto the structure. You can have stealth to approach the structure and blow a hole in it. As soon as you can make a hole, the whole structure mightvalready collapse as sensitive areas might melt or fry, making a bigger hole etc. But it might get even simpler. Possibly you can buy off lesser people in the civilization or place your own people. Like hacking, they might destroy, deactivate, authorise, remove authorisation or even give away control of large parts of the structure. If all else fails, grab a gas giant or two. At a certain moment you will overwhelm the firepower and shields, or possibly cause the sphere to use so much energy in areas that the structure breaks on it's own. But throwing planets generally requires a Dyson sphere to pull off... [Answer] The practical Dyson sphere builder will construct not a solid shell, as the material cost would be absurd and the physical stresses positively insane, but an orbiting swarm of layers upon layers of satellites. Indeed, these could be fortified impressively against all-round attack, as the defender could amass trillions of weaponized stations good for defending against smallish things that stations could feasibly fight against. The weakness here, though, is the fact that energy *can't* be repeatedly bounced around and re-concentrated without power transmission losses; each station generally makes do with what its solar panels provide and radiates the rest into space (perhaps for the next layer out to absorb for their own processes; Matrioshka brain, anyone?) So you can't exactly concentrate the full star's worth of energy onto the shields or weapons systems of any particular station at once. Such a swarm's key vulnerability would be to defeat in detail. As the swarm is spread out over quintillions of cubic kilometers of space, an attacker would only have to amass small, compact forces (admittedly, they may need a lot of them) capable of tanking the firepower of the few satellites they'll be in range of at any given time ("giant armored space battleships" suddenly don't seem like a bad idea here!), and then just sweep their ultra-fleets through the swarm, picking off everything around them and clearing out swathes as they go. Targeting the giant, fragile solar panels would be the obvious choice for an attacker to weaken the enemy's ability to fight back. [Answer] Surface area is the bottleneck. Let's assume you have some voidshields protecting you. This has to be subdivided into sections with each section having a bunch of shield emitters. Let's assume for a moment that the shields can absorb energy on a 1:1 ratio. Now imagine if the enemy starts bombarding A section of shield of say 1km. A miniscule area compared to the total surface area of the Dyson Sphere. They use an array of railguns 1 lightday away from the target. The railguns accelerate their projectiles to near the speed of light, making it easy for the railguns to relocate from any retaliation while the DysonSphere can't really move out of the way or detect the shots in time to shoot them down. Now imagine that the attackers fire enough projectiles that will hit simultaneously to equal the power output of the sun for 1 second. During the impact, the shield emitters on a 1km surface area have to run the entire sun's energy output through them. You can imagine that something will burn through with this much energy coursing through the entire structure. And let's not forget: The energy is distributed across the surface of the sphere. Energy farther than halfway up the sphere would require 7 minutes or more to reach the 1km surface area, with 14 minutes or more for energy located at the opposite end *assuming it could travel in a straight line at lightspeed*. So it is likely that a concentrated barrage timed to have each shot land at the same time, a trivial matter for this techlevel, would simply cause the shields to fail at the point of impact. You can then do interesting things with timing another barrage to arrive a fraction of a second later from a lot of angles, passing the shield and impacting on the surface kilometers away from the shield opening if the angle is steep enough. And that is ignoring the question: What happens with the energy of the impact? Is it absorbed? Deflected? Does the energy basically "stop" in place? With the exception of deflection you could exploit it an force a local overload to breach the sphere. [Answer] A few random responses: We don't know enough to build a Dyson Sphere with shields. By the time this is learned, anyone who may still properly be called your enemy may have techniques that circumvent a 3D sphere (things we might call today warp drive, wormholes, etc.) If your enemy is part of your general culture (say, US vs. USSR) then tech might be on a relatively even footing. But if it's just some random race in space, one or the other will be millions or billions of years ahead. If you're ahead of them you wouldn't even notice them. If they're ahead of you... they would in turn sweep you aside without noticing you. For instance their attack could focus *multiple* suns' power at you. Can the shields you mention be pointed towards any threat point, or are they simply fixed in all directions evenly? If the later, then an attack with many orders of magnitude less power, concentrated on one spot, could surely overwhelm those shields. Say we're standing outside your sphere, at 1AU (the earth's orbit). Even if your solar cell and shield generator were 100% efficient, the shield generated from 1m2 of solar cell couldn't be more powerful than the sun's rays on the 1m2, which isn't a lot of power. I think a few astronauts would be able to carry explosives or projectiles that have more power than that. Bigger "space battleships" would have greater cross section but more power. It seems like an astronaut, a ship, or a fleet could make a commensurately-sized hole in the sphere to get through. [Answer] # Dyson spheres are colossal by *galactic* standards English lacks words grandiose enough to convey *just how large* a Dyson Sphere is. The language peaks out somewhere between "astronomical" and "galactic". A Dyson Sphere is a megastructure larger than any naturally occuring astronomical object, including the stars they enclose. "Galactic" doesn't really fit, and a militarily-significant DS [dwarfs "astronomical"](https://en.wikipedia.org/wiki/Dyson_sphere): > > Also if assuming a radius of 1 AU, there may not be sufficient building material in the Solar System to construct a Dyson shell. Anders Sandberg estimates that there is 1.82×1026 kg of easily usable building material in the Solar System, enough for a 1 AU shell with a mass of 600 kg/m2—about 8–20 cm thick on average, depending on the density of the material. > > > A shell about 8-20 *centimeters* thick will be slightly more resilient than tissue paper, at least to any weapon being used by any sort of starship. You are going to need more material. A lot more. Either large parts of your DS are undefended, and thus easy to rip to shreds - or the whole thing will need to be thick enough to not crumble under the force of guns firing off from defense batteries or ships taking off. So let's be somewhat conservative. Use the high end of the cited guesstimate (20 cm thick for 1 solar system's worth of building material). And assume a uniform density of 1 meter will be enough to make the Sphere militarily defensible. Even massaging the numbers by making two very optimistic assumptions, *fifty* star systems are still required to produce *one sphere*. In reality, significantly more will probably be required. # It doesn't scale This simply can't be done en masse. A major power controlling hundreds of star systems would struggle to pull this off for even a small handful of Spheres protecting absolutely critically vital points. They'd more likely bankrupt themselves trying to transport dozens of star systems' worth of material to a single point. [Answer] ## The Worldbuilding The main problem with the question is conflating things that are theoretically possible, and things that are absolutely not. From a story building perspective, if you decide to bend reality to your world to a certain degree, trying to apply realistic physics or theory creates such conundrums. You mention "Void shields" and the energy they require, provided by a star. But truly the energy they need is inconsequential since there is no void shield physics to quote, void shields are not a thing. They could just as well need two AA batteries to run. Thus, to make your world balanced, you may instead put a reasonable limit on void shields, such as their size, need to reset or something of the sort. No need to touch Dyson sphere physics at all. ## The physics > > Anyway so far I think that perhaps it is simply impossible, like with any tech, to translate the raw power of the sun to such raw power of the station. > > > You're onto something here. The thing is, energy isn't something you just consume. Energy really is made of things being on one spot and not the other. When you restrict a flow, like a dam on the river or Dyson sphere around a star, there still must be an outflow on the other side. Otherwise, your dam or Dyson sphere will burst eventually. Thus, trying to consume all the raw energy from the star means you need to radiate it away on the outside of your sphere, otherwise it will get hotter and hotter inside. Even if you magically just consumed light, remember that machines powered by solar panels still heat up as they work. Thus, a Dyson sphere can still only consume a fraction of stars energy. It cannot be a truly enclosed sphere, even with the best technology and a bit of magic, this is still absolutely unimaginable. Truly, the strongest attack your Dyson sphere faces is from the inside. [Answer] Invincible - against what? If a sunstation is the ultimate form of combat vessel, then the obvious choice when you want to take one down is to bring a larger one into the battle. Or an array of other ones. Push come to shove, though, you can use strange matter. [A single strangelet can destroy a whole star system, it's just a matter of time.](https://worldbuilding.stackexchange.com/a/113655/21222) [Answer] If you try to build a Dyson Sphere at Earth orbit, you will need too much material. [Ton Day's answer](https://worldbuilding.stackexchange.com/a/184717/10324) has the math and the numbers are just too big. So, you build it much smaller and closer to the star. You mention "force shields" which probably means the sphere doesn't have to be much bigger than the star itself. It will mostly be a powerful force shield and its generators. And compared to defending against the star itself, defending against a battle fleet is easy. So the sun station itself is invincible. BUT, the important part of the star system isn't the star, it is the planets. That is where people live. If a foreign invader manages to invade and conquer a planet, the sun station has a problem. Sure, they could fry the whole planet without problems, but most of the people there will still be their own countrymen. On the other hand, the invaders also have a problem, the sun station will probably deny power to the planet making it costly to hold. In short, it will be a hostage situation, which have all sorts of potential for good stories. [Answer] It may come down to a matter of power levels, that is if we ignore other types of possible solutions to successfully attacking one. Let's assume a fraction of the Dyson Sphere's power is used for most needed internal things and that the most of it is successfully harvested and redirected to defenses/shields. If the Dyson Sphere has a star similar to our Sun, it would output around 384 YW (Yotta watts - 1000^8 ) of energy. Different stars may have different output yields, but still limited. In such a case all you have to do is build an energy weapon that exceeds that amount of power. And you can do that in multiple ways: a big ship powered a singularity core, multiple ships that merge energy outputs into one combined shot (like these [Species 8472 ships destroying a planet](https://youtu.be/YKmG0tTrJmY)) or using a stationary very long range direct on indirect weapon that could be power by anything starting with a bigger start, therefore having more energy output to work with. Those would be some the "fire with fire" cases. An alternate way is just to find something to destabilize that energy or even turn it against it's own system. Here you can find also multiple ways to do so, even with very limited power and/or specialized weapons. And finally, you have the option of sabotage. When something cannot be directly defeated or it is too inefficient/expensive to do so, sabotage is the good way to go. A power-off of the defense system and all that super sun-powered-shield becomes useless enough for an attack to happen. So clearly, that amount of power would not make it even close to invincible. At that civilization level, harvesting singularity gravimetric power could be a much more efficient way to have higher than a sun power levels using easier means of harvesting. [Answer] Consider a Dyson sphere with a radius equal to the Earth's orbit. That's an area of 2.79E17 square km. Currently there is something round-about some billions of processors on the Earth, more or less. So call it 10 billion, or 1E10. With even 1 processor per square km there would be 20 million times the total processing power of all of Earth. There would certainly be room for large numbers more, and there would be lots of energy to spare. There are people who think the internet is getting close to waking up. [Example](https://www.newscientist.com/article/mg20227062-100-unknown-internet-2-could-the-net-become-self-aware/), [Example](https://www.rtinsights.com/now-the-internet-of-things-can-be-made-self-aware/), [Example](https://www.smh.com.au/technology/a-selfaware-internet-not-so-farfetched-20120921-26ah3.html), [Example](https://techxplore.com/news/2019-01-closer-self-aware-machinesengineers-robot.html) With 20 million times as many processors working together you would have a daunting potential AI. In other words, a trivial relative investment in computing power would probably produce something unimaginably smarter than humans. And almost certainly much smarter than anything that could be sustained on merely planet sized systems. So it's pretty much impossible to predict what such an AI could or would do. It's smarter than any entity we have yet had experience of. Indeed, it would quite likely be able to do things we could not begin to comprehend. It would be like squirrels defeated by aluminum siding on a house. ]
[Question] [ The human body contains mana, the life force that can be transferred for use as a source for magic. The individual's capacity for mana slowly grows with time as the person ages into adulthood, finally reaching its limits during middle age, and then steadily declines. A mage must take care to control the amount of mana they utilize, as using too much at one time can sap their life force and lead to their death. However, a mage can substitute the mana of others for a magical source with no cost to themselves, transferring all the risk to the victim and leaving their own mana intact for use in less risky endeavors. The Incan empire is a brutal regime that is built upon magecraft, the use of magic to shape the natural world. It expands its territory through the conquest of its neighbors, taking captives as slaves to use as fuel for their rituals. These victims are ritually sacrificed on an altar by Incan priests, who use the mana released from the death of the victim as fuel to power their spells. However, this has the potential of backfiring. This system creates many enemies among Incan neighbors, who may band together or fight to the death against them, knowing what will happen to their people. It also can lead to slave revolts among captives. Luckily, magecraft seemingly provides an alternative solution. Within each male sperm cell is a microscopic organism known as animalcule, a complete preformed individual representing miniature versions of human beings. These preformed humans develop and enlarge into fully formed human beings through the process of conception and birth. Magecraft allows individuals to bypass this long and convoluted process to create life in order to create a perfect servant loyal to its creator, known as a homunculus. These homunculi are grown within a specially built cauldron designed to hold magic brews. This brew is filled with various ingredients, such as eye of newt, as well as other lay ingredients, such as cow intestines and the "seed" of a male. The resulting "child" emerges from this concoction as a fully grown adult, bound to obey its master's commands. Although they are intelligent, homunculi lack free will and individuality, making them the perfect servant. The Incan empire have considered the potential of swapping out captives for homunculi for the purpose of using them in their rituals. On the surface, the benefits are obvious. Creating a literal slave race bound to your will would make methods of control much easier and cheaper, mitigating risks. As they are created from magic as adults, they contain all the mana they need at birth without having to go through the long timeframe of aging to an appropriate level, saving time. In addition, they can be grown in bulk, as the ingredients aren't exactly rare. As such, the theory of replacing captives with homunculi in the flesh economy is sound in theory. What would preven this system from working? [Answer] Put quite simply, sacrificing an homunculus will not gain a net increase in mana. Creating an homunculus costs mana. Sacrificing an homunculus gains mana. However, because no process is 100% efficient, it takes more mana than a homunculus contains to create one, and sacrificing it yields less mana than it contains. The cycle is therefore a net loss. Sacrificing humans, for all that they tend to not want to be sacrificed, yields a net gain, even if relatively small due to the inevitable devaluation of human life that sacrificing people in job lots would cause. It doesn't cost mana to grow a human. The math is simple: Human sacrifice = net gain. Homunculus sacrifice = net loss. No doubt it was tried, and found to be disappointing. [Answer] **Good luck sacrificing homunculi.** They are freaking incredibly tough. You think one is dead but you have got no mana from it. Then you check and not only is it not dead but it is getting back up. Excessive measures to ensure death prove not excessive enough. People tell stories about times you get the mana from the sacrifice and then later you lose it again because the homunculus has claimed it back and is going about its business. People die so easy in comparison. The priests got lazy - a litty stabby stabby and you got your mana. Easier to stay with people. [Answer] Disaster followed. They sacrificed homunculi, there were earthquakes, storms, drought, and other disasters. Whether the gods were offended, or the mana was bad, or the thing was a total coincidence, anyone who suggests trying it again will find himself the next sacrifice. [Answer] Homonculus mana makes the absorber servile, much like the homonculus it comes from. Even the most ruthless tyrant ends up a will-less servant carrying everyone's water after they try it. Not ideal for ambitious young Incas. You could riff on it and have it that some who tries it actually end up as very nice, humble people. [Answer] **MAKE THEM FEEL IT** The homunculus suffers for its master. It does work, it takes hits. It dies for the master. But it still feels all the pain because someone has to. In rare cases the pain the homunculus feels can be shared by the master. It most commonly happens when the homunculus is unconscious. If it is unconscious but not yet destroyed then any suffering its body feels is transferred to the master. Although the physical impact is absorbed, the homu is not consciously present to absorb the subjective experience of the impact so the master feels the pain instead. E.g The master may feel his leg to be broken even though it remains intact. This is more severe with homunculi that have already endured excessive suffering, and whose master's have accrued much karmic debt. Forming a connection between the masters and their homunculus can increase the cost of the sacrifice to the point where it is no longer economical to sac them for mana because it also costs life force. Some people in your story might do it, but it's not generally profitable. You don't get back more than the value of the thing you sacrificed or else the system is broke. [Answer] Mana only exists in free-willed spirits. Male sperm contains the animalcule, but the female egg contains the anima that inhabits the animalcule. If you try to create an homonculus out of both male and female gametes, it turns out to be no different than a fast grown rebellious normal human. But that is not all: as I said, mana is tied to the free-willed spirit itself, to the point that it is almost inversely proportional to innocence. So if the spirit (or mind, if you are a materialist) has not developed with the magically grown body, its will have the mana of a newborn baby. [Answer] **TL/DR: Mana is not released from the death of the victim. Mana is borrowed from the victim, then given back. Mages also get exhausted after using too much mana.** **To answer your question, stealing mana from homunculi is dangerous - when the homunculus dies (this cannot be avoided), the stolen mana becomes dead and can severely weaken or even kill the user.** Mana is innate. Humans are born with it, and their capacity for mana grows with the passing of time until it reaches its peak - then slowly declines (much like, say, a person's height). Hence, the strongest mana comes from the user themselves, so the most powerful spells are cast only by the user's own mana. However, it IS possible to take mana - not without consequences, of course. Mana, when borrowed from a victim, can be used to shield the user's own mana. When a user takes a victim's mana, the user can cast spells with the victim's mana to protect his *own* mana. The victim, on the other hand, is left without mana. He is powerless until the user returns the victim's mana. Here is where another factor should be added: exhaustion. During normal circumstances, mana can run out if a user casts too many spells. When the tank is empty, the user will have to wait before his mana regenerates again. However, when a user takes a victim's mana, the stolen mana is immediately returned to the victim when the user's tank runs empty. Mana can be returned in a variety ways. Remember that humans only have so much capacity to store mana. The first way to return mana is willingly - that is, if a user decides to give the mana back to the victim. The second way is burnout: if a user runs out of borrowed mana, then that mana is returned to the victim by default. The third way is by death: if the mana is too much for the user to handle, the user dies because their capacity is not large enough to hold their own mana *and* the stolen mana at the same time. This is one of the main reasons why homunculi are not used for mana swapping. Homunculi already have a full capacity for mana when they are created; hence, many of the mages who steal mana from homunculi die when their capacity is overstuffed.. But what happens to the mages who *don't* die that way? Let's say a mage was actually strong enough to hold all the homunculus' mana at once. What would happen to him? This brings me to my next question. What if the victim dies while the user still has the victim's mana? The user can't return the stolen mana to anyone, so the dead mana is stuck inside the user's body. Here, one of three things can happen. Firstly, the dead mana can eat away at the user's own mana, so as all the mana decays, the user is eventually left with nothing. Secondly, the dead mana could merge with the user's own mana, resulting in an abomination. In this case, the user can no longer cast spells correctly due to his warped mana. Third (and arguably the most gruesome), the dead mana becomes infected and spreads throughout the rest of the user's body, corrupting his mana until he dies a slow and painful death. Now, it wouldn't be outrageous to say that homunculi die when their mana is stolen - after all, mana is their very foundation. Therefore, mages tend to stay away from swapping their mana with homunculi. The consequences are simply too grave. [Answer] The most direct approach would be that, due to their different origins, homunculi don't possess mana, in the same way they don't possess free will. If that doesn't work, they can have only the minimum needed for survival. Any working would be fatal to them, and produce a barely useful minimum of mana, possibly even less than it took to create them. Combine this with the effort of creating them, and you'd have to breed (and temporarily feed) a battalion of single-use homunculi for a single spell. [Answer] A child's mana (or a homunculus's) is linked their parent's. This is a part of the natural order that helps parents train their children in magic, and also is partially responsible for the devastation felt when losing a child. Normally a parent may have a dozen children with a few surviving to adulthood. The mana drain on the parent from these few losses spread out over several years is noticeable, but recoverable. However, the natural order is less forgiving at scale, when mages start trying to use bulk homunculi. Each homunculi spent drains the parent a little bit, and too many too quickly can be fatal. Thus, a hybrid system was created where slaves are captured, and they are used to generate homunculi, who are not linked to the mage syphoning their mana. [Answer] **They Require Mana to Create** [![enter image description here](https://i.stack.imgur.com/tDmB5.jpg)](https://i.stack.imgur.com/tDmB5.jpg) Human beings naturally draw mana from the Source at the Earth's core. First to be alive. this takes 9 months. Second to grow. This takes maybe 18 years. Third to cast spells. The only cost here is time. When you create a humonculus you have to cram 20 years of mana into the thing to create life and grow it to full size. After spending all that mana you CAN sacrifice the humonculus and get back some of the mana. But what would be the point? It is the difference between burning wood from trees, and making a machine to filter carbon from the air to burn. The machine costs more energy to run than it creates. [Answer] **Homunculi don't have full mana because they're created only from sperm.** Basing this on @Ivella's comment. The homunculi can function well for mundane purposes, but because they are not created from both sperm and egg, they don't have the full mystical characteristics of a natural creature. It's even possible that the mages aren't even clear on this. In a pre-technological culture that believes, like @Ivella says, that a person "comes a sperm" (actually they'd say "from the semen" since they haven't observed sperm cells), they don't realize there is a female contribution which is also crucial. [Answer] You already established your rule why it wouldn't work: > > The individual's capacity for mana slowly grows with time as the > person ages into adulthood, finally reaching its limits during middle > age, and then steadily declines. > > > The questions that need to be answered are: * What is mana? Actual life force, spirit/soul, blood, calories, bodyheat? * How does one replenish mana? A potion, food and drink, time? * Can homunculi ingredients be used as mana? * Does a created homunculi only contain the ingredient's mana at birth with the capacity of an adult? [Answer] # Mana from different sources do different things. Why not use animal sacrifices instead of humans? Because while each animal's death releases a comparable *amount* of mana as a human's death, it's not the sort of mana the Sacrificer tribe needs for those spells and rituals where they use human sacrifices. ## Animal mana is useful...to an extent You can draw moderate amounts of mana from animals (and humans) without killing them and small amounts without harming them. That's one reason why witches and wizards sometimes have familiars - they can tap into their familiars' mana for certain spells and brews and rituals. The Sacrificer tribe does, in fact, use the mana from killing some animals for other spells, just like many other tribes do. But for example when you want to unleash an earthquake on a neighboring tribe, augury mana won't do, nor will clairvoyance mana, so you can't use the mana released by killing birds and rabbits and cows and sheep. A bear might release suitable mana, but they're dangerous and difficult to capture alive. ## Human mana is very versatile Mana drawn from humans is very versatile and can be channeled and transformed into mana for most any magical effect. Much like stem cells can develop into any type of cell the body needs. Once transformed, that mana is no longer versatile. You might be able to reuse some of it for something similar, but you can't turn animation mana into scrying mana or fire mana into wind mana. ## Homunculus mana is the wrong kind The mana used to create a homunculus is the sort used for animating inanimate objects and growing plants and animals. Killing/destroying it releases that mana, but it's no longer versatile. It can only be used for similar uses - growing crops, moving statues, etc. And you get less usable mana out than you put in. In theory you could sacrifice a large group of homunculi and reapply some of the released mana to animate a giant statue or grow a vegetation wall. But that's not the sort of magic the Sacrificer tribe is interested in doing. Nor are they patient enough to build up the needed homunculi for the task when there's an easier, faster alternative. [Answer] ### Despite being magical constructs, a crowd of Homunculi contain much less extractable Mana than any single human would Life energy and magical energy are not the same in quality or quantity. Mages can cast power spells because a small amount of life energy can be turned into large amounts of magical energy. As you mention, over exerting can cause the loss of life so the conversion is not infinite. Homunculi are made of magical energy, not living energy, so even though they may be pumped full of different amounts of energy for different constructs and roles given, for the use of rituals, life energy simply works to a far greater effect. In theory, yes, you could farm and mass produce, optimizing the process and finding cheaper alternatives for resource costs, and make a sustainable source of ritual fuel over a period of time. Ooooor... You can just sacrifice one person to get a month's worth of the same production in a few minutes. Even more so when you have plenty of living batteries free to be scooped up and held in cages for when they are needed. ### This may be a turning point in itself Since the Sacrifical tribe isn't bothering to try farming mana from Homunculi, in order to resist the growing threat neighboring countries are pooling their resources to build a large scale operation in order to get enough fuel to resist and fight back the enemy. Without sacrificing people themselves, it may be the only way to level the field in having enough mana to not be rolled over by sheer force. They may discover methods of, rather than producing more mana, using it more effectively by building specialized Homunculi designed specifically to focus, multiply, or enhance mana being extracted from sacrificed constructs. They learn in the process though that it is in some way tainted and causes environmental problems with local magic to harness mana in such a way. [Answer] ## He's A Soulja (But Not Really) So, you want to know why your artificially created being who has no free will or individuality cannot be used to generate mana? It is simply because, unlike humans, homunculi do not have souls. And every mage has been told since they were a wee initiate to the arcane arts that the soul is where mana is generated. To be clear, "soul" in this case does not necessarily mean anything other than "that thing which lets humans generate usable mana". Think of it as shorthand for some known but hard to study phenomenon. In this case, your mages know that humans generate mana that they can tap into via sacrifice but homunculi do not. So there is obviously some difference between the two. The other differences are having free will or not, and how they are created/born. Taken altogether it would be pretty simple for a mage to determine "The homunculi process causes them to be born missing some fundamental aspect of humanity which allows us to generate mana. We call this aspect 'the soul'". The nice thing about this from a story telling perspective is that it opens up a couple of different plot hooks you could explore. Maybe someone creates a homunculus that is able to generate mana and has to keep the knowledge secret from his rivals. Maybe a homunulus develops free will but has to hide it from it's evil master. Maybe the real problem with the creation process is a lack of feminine energy, which gets discovered by a rogue female mage. You don't even have to really delve into the religious or spiritual ramifications of souls, since they are mostly used as shorthand for "human sapience". ]
[Question] [ I’m writing a novel where people from our universe move to another. The other universe is a fantasy one with medieval technology. These people have the help of an advanced AI that contains the history of the last universe down to the specifics. Now I was wondering, when these people inevitably develop aircraft, would it be possible for them to skip piston prop engines in favor of jets? [Answer] If you already know how, and you just need to do fabrication from scratch: jet engines, no question. Yes, building proper turbine blades is a bigger technological problem than building pistons, cylinders, and crankshafts... but jet engines don't need turbine blades. Pulse jets are just about the simplest form of aircraft propulsion you could possibly devise. You can build one out of a single piece of sheet metal and a spark plug, or a single bent pipe, with zero moving parts. If you want slightly better reliability, you can build a more complicated one with some slightly more involved interior geometry and... *one* moving part. Now, pulse jets have a lot of problems. They aren't the most efficient, they tend to get really hot, and they are *really* loud. There are good reasons we don't use them in manned aircraft in the real world. But if you just want to build the first thing you possibly can to get in the air, as quickly as possible, with a minimum of prerequisite infrastructure... a pulse jet engine is it. [Answer] With the all knowing AI at hand, anything would be possible, so you could handwave this as you see fit, surely? The issues are probably ones of fabrication... people have made piston engines for centuries, because the key elements that need to be made with the highest precision are things that can be handily fabricated on a lathe, and lathes are the easiest precision machine tool to construct. Turbine blades on the other hand are not nearly so simple, and tend to have inconvenient geometries and be made out of more inconvenient materials that need complex precision grinding tools. The earliest "modern" gas turbine designs dated back to 1791, but the problem was that engineering and manufacturing technology just wasn't up to the job of making a practical working device that for over a hundred years after that, and it was nearly another fifty years before one could fly. Compare that to the first use of a steam-driven propeller aircraft (a dirigible) in 1852, and a piston-engine-driven propeller aircraft (in 1903), with no shortage of commercial, military and academic interest in that time. That's not to say that you couldn't do it. You don't need modern computer-driven machine tools to make turbines after all, but building up the necessary industrial base, high quality metallurgy, precision machine tools and competent operators and engineers is non-trivial, even if you know exactly what you want, and what you need, and have all the educational material required. This is the problem that all time-travellers face, see many previous questions on this site on this very subject! [Answer] As noted in another answer, fabrication is the key. Piston driven steam engines predated working steam turbines by more than two centuries, because any competent blacksmith can make a simple piston and crank (and a rather skilled one might be able to build a multi-cylinder version), and machine tools for this kind of work existed by the late 18th century -- where turbine blades and the wheels that carry them are completely beyond hand forging and are a challenge for manual machining processes. Now, step up to internal combustion. The crank, piston(s) and cylinder(s) of a steam engine are just waiting to be converted, as the same parts can both compress and expand the working fluid; only a slightly more complicated valve drive is required -- but for a turbine, there must be a separate compressor stage (even if mounted on the same shaft, as with simple early turbojets), and those blades require significantly different design than the ones in the hot section. Presuming your crosstime colonists start by building machine tools (lathe and shaper, at the minimum), they can build piston engines starting the day after the machine tools are finished and their cutting bits made. Even with detailed design, they'll be decades developing the material infrastructure to support the metallurgy for a 1940s technology turbojet -- and still longer making one that's as efficient as even a 1970s turbofan (which requires still a third set of blades with a third design). [Answer] No. In addition to all the difficulties involved in fabricating the engine itself, which the other answers address, piston engines and jet engines serve different purposes. Basically, jet engines are for when you want to go fast, piston engines and propellors are for going slow\*. The question you don't ask is exactly why your medieval culture is "inevitably" developing airplanes. If they are planning on developing commercial air travel\*\*, then they need to build not only the engines, but the whole infrastructure. They need aluminum and other lightweight alloys to build pressurized airframes, miles-long paved runways, radio communications and navigation, instrument landing systems for inclement weather, and much more. On the other hand, if they just want a few airplanes for other purposes, given a halfway decent piston engine, you can build a decent airframe from wood and fabric. That plane can be built to take off and land on a few hundred yards/meters of reasonably-smooth grass or dirt, doesn't really need radios, and you just don't fly if you can't see. Even if you are intent on replicating the modern world, there are many practical applications for which jet engines simply don't work well. Visit any small airport (or even a medium-sized one) and see how many small planes there are with propellors on their noses. PS: If you want jet engines powering commercial aircraft, we really need to think about developing the supply chains. I mentioned the airframe problems, but have you really thought about what goes into an efficient, modern jet engine? For the turbine blades, you have to figure out how to mine & refine things like nickel,chromium, cobalt, and rhenium: <https://en.wikipedia.org/wiki/Turbine_blade#Materials> Then for your hot section, you want things like titanium alloys: <https://aviation.stackexchange.com/questions/25645/what-material-is-used-to-make-the-hot-sections-of-jet-engines> Refining titanium is not an easy task: <https://www.essentialchemicalindustry.org/metals/titanium.html> Then to fuel your airplanes, you really need to develop the whole fossil fuel industry. Once you've done that, you start putting megatons of CO2 into the atmosphere, which means that in a couple of centuries your new world has serious problems with global warming... \*I'll skip over turboprops, which basically use a jet engine to drive a propellor. But compare the cost of a present day small turboprop with an equivalent piston-engined plane, and you'll see why smaller ones are fairly uncommon. \*\*This would mean that, given that they have the AI with all this world's history, there's a strong presumption that these people are unable to learn from experience. [Answer] As they are now, piston prop engines are much easier to construct and get working properly than jet engines. They are enclosed systems with very sturdy components in their most basic forms. Without prior in depth knowledge about how propellers work, inventing a jet engine from scratch would be extremely challenging. However you state you do have prior knowledge about this technology, so this would definitely not be impossible. If you do have the full technical specifics of engine technology before developing it, it is a simple question of what you want to build. Obviously it would be better to skip inferior technologies in favour of more advanced ones, if this is an option. Even if it is harder to build these engines, it might be easier to spend time developing the base manufacturing processes a little longer so a step can be skipped, rather than develop a whole technology you know will be redundant as soon as you finish it. [Answer] Theoretically, a turbine is mechanically simpler than a piston engine, and the principle could be understood by anyone familiar with a windmill. Leonardo da Vinci's "roasting jack" could be understood as a simple turbine devised to harvest the heat energy of the fire to perform mechanical work. [![enter image description here](https://i.stack.imgur.com/3oIdX.jpg)](https://i.stack.imgur.com/3oIdX.jpg) *Leonardo's roasting jack* However, the real stopping point is the supporting technologies that would allow the building of usable turbines, as many other posters have already noted. A [gas turbine](https://www.britannica.com/technology/gas-turbine-engine/Development-of-gas-turbines) was described in 1791 and a working model actually built in 1903, and the [pulse jet](https://en.wikipedia.org/wiki/Pulsejet#History) was also described in principle in 1867 and an early form built in 1906, but it took until the late 1930's before other technologies like machining, high temperature alloys and so on made these devices at all practical. In order to move directly to turbine powered machinery, the use of rotating machinery, including water wheels and turbines, as well as steam turbines, will have to be "forced" so developers will continue working on these devices and a large enough pool of engineers, mechanics, metalworkers and so on are created to support the continuing development of turbine devices at the expense of piston devices. This would also extend to the cutting of gears and development of efficient transmissions, since turbine devices for stationary and other mobile applications generally turn far too fast to be harnessed directly to output shafts. So, assuming the AI can provide the "steps" to instruct the civilization and the idea is planted and supported early enough, it may be possible to develop turbine engines early on and have them used to power aircraft. [Answer] A critical design difference is that a piston engine works with a discrete cycle that can take any amount of time to complete (within reason) but a jet engine operates continuously. If you look at the early history of the steam engine, you can make a useful practical device that only operates at one "rev per minute". Of course with an external combustion engine, the fuel is burned continuously, but you can stop and wait as long as you like until you have enough steam pressure to drive the engine through one cycle. There was a long time interval between making an *internal* combustion engine and the original steam engines. A steam turbine is a logical development of a steam piston engine, with external combustion to produce a continuous supply of high pressure steam. To build a jet engine, you need both turbine technology and the internal combustion technology, plus a compressor that can get enough air into the combustor to produce a useful amount of power. So to *start* by designing a jet engine, you would have to create several novel pieces of technology and get them all to work together, all at once. If your world had access to "the history of the last universe" and the ability to *understand* that history, they would probably realize themselves that progressing one step at a time was a better option. [Answer] There is one type of jet engine that is easier to build than a piston engine and in an alt-history or alt-universe setting could be fun to contemplate. It is the engine used by the the original cruise missile - the V1 flying bomb: a **[pulsejet](https://en.wikipedia.org/wiki/Pulsejet)**. ### Pulsejets Starting one is not easy but you can easily learn the skill with practice. People have built pulsejets in their back yards with just good welding skills and some metal pipes. Google "pulsejet" and search for it on youtube to see some examples of homemade pulsejets. Pulsejets can generally be divided into two types: valved and valveless. The V1 pulsejet (and the type commonly used in RC airplanes) are valved. A lot of homemade pulsejets are valveless. The advantage of a valved pulsejet is for the same amount of power you can build a smaller/lighter engine. The advantage of a valveless pulsejet is there is no mechanical part to wear down. Here's an example of a homemade pulsejet (valveless): <https://www.youtube.com/watch?v=zsXWspo5hrc> And here's a commercial pulsejet (valved): <https://www.youtube.com/watch?v=_h6D47Lkfcw> A side note: Pulsejets are **very loud** and gives you a stem punk vibe. They make a distinctive buzzing sound (a bit like an overworked truck engine) which gave the V1 the nickname buzz-bomb. --- ### Turbojets Turbojets are a bit more complicated to build but they don't have to be overly engineered like commercial or military jet engines. Early turbojets used centrifugal compressors and were relatively simple machines. The main issue with early turbojets was that the metallurgy of the time was not up to scratch. For example, the German jet engines of WW2 required a total overhaul after just 50 hours of operation. But if you are willing to do extreme maintenance then you *can* do it (even if badly). Modern jet engines use fancy alloys. As a bonus, here's the same "home made pulsejet" guy above building a "home made" (albeit using a commercial car turbocharger) turbojet: <https://www.youtube.com/watch?v=83jH0sVCM9Q> [Answer] # Yes! You can build just anything. You do not need much to start. # You need *only* 3 things You have an advanced AI. You can build just anything: Things that you know. Things that you can imagine. Things that you can not imagine. But to build something, you need these three: # The *physical elements* as raw material Any other raw material substance can be made by chemical processing. For good jet engines, tungsten is useful, so the blades do not melt. But use iridium, if you can afford it. # Energy Whatever you want to process to create useful substances, and whatever you do with them, you need at least some energy. And if you have lots of energy, you can take great shortcuts. Ask your AI for instructions. Solar cells are hard to build, use water power to start. # Time When you need to build anything "from scratch", you may get ideas from your AI that are possible, but time consuming. For example you want to build a tungsten turbine blade. You need to find tungsten ore, and create a piece of tungsten of roughly the same shape as the blade will be, a little larger. Your AI knows the geometry, but you do not have a CNC machine. But you can build a very simple EDM machine, and use spark erosion to shape the part. But you can ask your AI for a suitable tungsten alloy, help her to build a 3D printer, let her use it to print a good 3D printer for metal, and print the blades. That has the advantage that you can make them hollow, saving much material, and making them lighter. (In general, make good use of the AI to simulate and optimize parts.) Oh, and make sure that your AI does not kill you, just as we should in real live. ]
[Question] [ Suppose that there are 2 interstellar empires at war with one another, both armed with FTL drives which cannot be used within a certain radius of huge gravity fields, stars, gas giants, etc. Another thing to note is that both empires use the same FTL tech, which they had both independently researched, as it was the Apex Technology or something. So the 2 empires will be at war with one another. On their first battle against one another, they stand off against one another from millions of miles away shooting with their cannons. Suddenly, one of the ships from one side suffers a critical hit, and detonates, wiping out both fleets, turning the local planets to plasma, and solidifies the local star by fusing all the helium into lead all in a flash. The blast then rippled outwards, FTL and completely irradiates all systems in a large(25 parsecs) radius. Now, both empires now know the extreme power of the explosion when their FTL ships explode, and they decide that they don't want to fight ship against ship anymore, but they are still at odds with one another and want to fight. So, that is a bit of the setting, now for the actual question. How would 2 interstellar empires fight in space if they are both extremely unwilling to blow each other's ships up Notes * There is FTL, and is outfitted to most Cruiser and above sized ships. * Both empires want to fight, but they don't want to blow up each other's big ships. The ships can be attacked on small scale and boarded and neutralized that way. * Both empires had never actually seen the FTL drive explode like that, but quickly deduce that such an occurrence would be very common if they kept fighting like that. * Between the 2 empires, they probably easily lost a dozen or so systems from the first contact * Take note that the huge explosion is caused by huge chain reactions from the FTL drives of both fleets, and the local civilian ships as well. * A single lone ship detonating it's FTL drive would be still be enough to wipe out a large portion of a single star system, but it would easily also trigger any other FTL ship in the system. * MAD would probably not be in play, not until one empire is beaten all the way to their home world, as the detonation would have very real consequences. HUGE NOTE: This question is more about how 2 empires would fight, not about how to weaponize the FTL drive. [Answer] Based on that chain of events, if I were supreme dictator of one of these empires, I'd be aiming to demolish their planet-side infrastructure. If they have any massive, unmovable, space-borne infrastructure... bomb the crap out of that too. As I actively want to keep the enemy fleet's ships intact, I wouldn't engage them in any offensive capacity. Crews need food, and food comes from supply-lines. I'll attack there, and starve my enemy into oblivion. **Why?** After the first encounter, the one that resulted in the deaths of ***b***illions Of my citizens, I now have to fight two battles; one against my enemy, and one against the public outrage against my lack of foresight. It was *my* government that commissioned the development of the antimatter cannons, and the quark torpedoes that have been blamed for the *largest loss of human life in recorded history*. Whether or not this is true is irrelevant; the public *thinks* it's true, and the public wants vengeance. To keep my reign as ruler, I'm now forced to use a strategy that minimises the chance of further 'incidents.' My generals and military advisors turned to complex computer simulations and history books alike. Every analysis came to the same conclusion; combat against a FTL-enabled ship, or a ship's crew was too much of a risk. If for no other reason than the deliberate detonation of an FTL-drive is a sufficient deterrent from boarding. The official strategy; nuclear bombardment of all hostile planets. **Being The Attacker.** Cities don't move. They remain in the same location on a planet's surface. Planet's spin very predictably, and orbit very predictably. We can easily compute where a planet will be at any point in the future. Computing where a certain city is going to be isn't much harder. We're capable of this today: we plot the paths of meteors and space-junk as they enter the atmosphere. Now, to bomb them; you don't need much of a *missile*. It's more like 3D bowling. All you need to do is aim well, give your missile the right nudge, and *gravity will do the rest for you*. To increase your chances of not being caught, you wouldn't take the simplest shots. No, you'd aim your missiles to sling-shot around other planets and moons. **Being The Defender.** Is both easy and hard at the same time. The process: Look for anything moving in space, compute its path, shoot it down/nudge it away if it'll hit your planets. The Easy Part: The laws of physics that allow you to aim your atomic-bowling-ball-missile are the same laws that allow you to work out where missiles are coming from. This narrows down how much space you have to search in. The Hard Part: They call it space for a reason: there's an awful lot of it. You still have to do an astronomical(it's a pun!) amount of searching. And you have to be doing this constantly. But that's not all! Any smart adversary is going to expect you to look for missiles, and will make them as stealthy as possible. This basically involves painting them with the blackest paint of possible, and making them sub-zero temperatures. **Where do I station my fleets?** The bulk of my navy is relegated to defending against incursions, particularly bombardments attempted against me. Standing orders are as such; be on constant vigilance for rogue objects in colonised star systems. Take picket in orbit around planets on the solar system edge, where enemy ships have the greatest opportunity to attack and escape from. The exception to the above rule applies to; the stealthiest ships, and ships with the largest (launchable) cargo space. These will be used to attack. Massive, concerted, assaults will be used to draw in defending fleets. This will open holes for attack elsewhere. [Answer] I don't think your setup will actually result in the two sides fighting using lesser weapons, it just doesn't make sense. If the enmity between them is so great that losing multiple entire systems doesn't make them reconsider fighting, they aren't going to put on the kid gloves now. I see a couple of way this war could go. ## "Strike fast. Strike hard." -Fleet Admiral William Halsey If there is no way to track/intercept ships going FTL, just send a fleet of suicide ships to all parts of the enemy empire that aren't too close to you and **boom** war over. ## "Give me a lever long enough and a fulcrum on which to place it, and I shall move the world." - Archimedes What you have isn't an FTL drive, it is a weapon that can destroy everything within a 25 parsec radius. The trick is to position it so that as much of that 25 parsecs is within enemy territory and as little as possible is within yours. Step one is to withdraw as much of your population and infrastructure from the border areas (within 25 parsecs) as possible. How much effort you put into getting civilians out depends on what kind of an empire each side is. Step two is to use cover the frontier between the empires with a fleet of suicide ships, spaced out as far as possible while not allowing any gaps in sensor coverage to allow enemy ships through. Any attempted penetration results in the ships detonating, taking out the attacking force. Be sure you have new ships waiting a safe distance away to replace the ones lost. If the sensor range is less than 25 parsecs this will be expensive, but don't worry, it won't last long. There will be a 50 parsec wide "neutral zone" between the empires until someone makes a mistake and lets a ship through, at which point **boom** war over. ## "Diplomacy is the art of saying 'Nice doggie' until you can find a rock." - Will Rogers If your empires are too small to sustain those levels of losses you need to take a more subtle approach. Your situation is similar to that of the US and USSR in the early 1950s. Both sides have the capability to destroy each other but don't have the stomach for using them. In effect, the FTL drives are the interstellar equivalent of strategic nukes, while you want *tactical* nukes. So you engage them in diplomacy, talking about how terrible the loss of life was, blah, blah, blah while developing a smaller, weaponized version. Once that is ready, you fly ships into their territory from all along the frontier. If they attack your ships will explode wiping out a large amount of their military (your other ships are sitting safely at home). If they don't attack, you fly to their homeworld and **boom** war over. ## "A Strange Game. The Only Winning Move is Not to Play" -WOPR All these outcomes will result in huge casualties and large portions of the local galactic region will be destroyed. If that isn't what you want *don't have two empires with absurdly over-powered super-nukes fight*. [Answer] > > MAD would probably not be in play, not until one empire is beaten all the way to their home world, as the detonation would have very real consequences. > > > I fail to see how MAD would not instantly come into play; Tom Anderson's response directly leads to a MAD world as does Tim B, nogrodoth, and user6511. You have created a MAD situation where there isn't a good move as the only way to "win" would be a first strike that is so devastating that it completely wipes out all ability to counter attack (which, given FTL starships seems relatively impossible to accomplish as only a few starships need to self detonate in strategic locations to have an unacceptable counter-strike). In the Cold War the US and Russia were still able to go at it and even fairly directly, they just needed to have proxy's set up. Jim2B's answer creates a proxy situation of sorts, as does in fact feas response which covers the very real situation that non-military competition became huge during the Cold War (and to today) between rivals, a way of determining who was 'best' without actually destroying the world, as in the Olympics and Chess, so forth; it is again another form of proxy warfare. Which shows that the form that the proxy warfare takes can be hard to predict and may be varied, such as with great shows of strength or of technological achievements as with the Space Race. Diplomacy will certainly pick up between the two sides even if arms build up also happens, and each side will be looking at ways of gaining first strike capabilities, defending against first strike, negating defensive measures, and negotiating treaties to stop such research, and then figuring out ways around the treaties that don't lead to retaliation. For example, spreading colonies and expanding the empire would be a way to try to mitigate against a first strike, so there would probably be treaties signed limiting the number of new colonies; both sides would probably then continue to create things that are not quite colonies or that aren't technically "new" in violation of the spirit of the treaty they both signed and both would be aware that the other was doing it, until a new treaty was signed, etc. [Answer] The Sci Fi RPG, [**Traveller**](http://en.wikipedia.org/wiki/Traveller_%28role-playing_game%29) utilized a concept that would make a lot of sense in this situation. They called the concept [Battleriders](http://wiki.travellerrpg.com/Battle_Rider_%28book%29). The carrier / battlerider concept uses a large mothership / carrier but they carry full sized combat warships instead of fighters. For your use, the mothership / carrier would possess the FTL drive and do its damnedest to stay far away from battle. Heck, in your universe you could have both sides purposely leave their mothership / carrier weaponless so that the other side won't be tempted to fire upon it. All combat is conducted by the battleriders (who do not possess FTL) far away from the mothership / carrier. The losing side warps / jumps / scoots their mothership away, perhaps leaving any surviving battleriders behind. * A mothership / carrier without its battleriders would be like a giant freighter. * A battlerider without its mothership would be effective at system patrol/combat but would be the interstellar war equivalent of a "fixed defense". Depending upon many of the details you decide (such as FTL engine recharge times), the concept of operations (CONOPS) might be: 1. Carrier / mothership jumps in 2. Battleriders undock and accelerate away 3. Carrier / mothership takes a mini-jump into the system's Kuiper belt 4. Carrier / mothership awaits the coded recall signal 5. After a predetermined amount of time with no signal, carrier / mothership assumes a total loss and jumps away. Alternatively given Solar System travel times for accelerations of under 10gs, battles will take months or in some cases years. So the carrier / mothership leaves to go do other things. 1. Carrier / mothership jumps in 2. Battleriders undock and accelerate away 3. Carrier / mothership jumps to the next system on its itinerary 4. After a predetermined amount of time, carrier / mothership returns to agreed upon destination in Kuiper belt for Battlerider pick up. What happens when one side doesn't follow the agreed upon combat SOP? [Answer] You might be able to force a surrender if you moved positioned your ships in range of the other side's most important planets - saying "Hey, surrender or I'll fire on all your cities, and if you shoot me, you'll kill yourself". Assume ships are programmed to self-destruct if their hull is breached, and inform the planet of the same. You might not want to tell the ship's crew though. I'd imagine whichever side can arrange that first would most likely be able to win. Unless the loser would rather die than submit. Either side, though, would be able to do this pretty easily, as I'm not quite sure how you could possibly detect and intercept a ship moving faster than light, before it gets to your planet. If such detection were possible then it'd be a game of chess (or perhaps a closer analogy, a Chinese checkers version of American football- you win by getting yourself in the end zone). Each side trying to out-maneuver the other to position their ships in range of the opponent's most vital planets, while blocking their opponents from doing the same. If such detection would not be possible, then the winner would be whoever mobilizes first. Or more likely, both would lose - each one with their ships positioned outside the other's planets, destroying the cities below. Maybe whichever one has the best aim then, and so destroys enough of the planet to persuade that side to yield. [Answer] **Step 1:** Seed space between all my planets and all the enemies planets with small mostly inert FTL drives. One every 5 parsecs should do. Tell the enemy that you have done this. That instantly disarms the use of the ships as a weapon. The chain reaction caused by an exploding ship explodes the entire web of ftl drives, and any ship near them. (This is a high risk strategy, obviously) Station FTL drives in all major cities. This protects against long range bombardment. This is mutually assured destruction taken to the (il)logical extreme. The use of any high powered weapon becomes instantly and terrifyingly taboo. **Step 2:** Develop a pod capable of holding an armoured trooper. The pod has integrated cutting blades, but no explosives of any kind. Any enemy ship is attacked by a swarm of active, semi-active and inert pods, some empty, some filled. If a pod finds it's way to an enemy ship it scans for the presence of FTL radiation to check that it's no where near the drive section and then drills through the hull delivering the armed trooper. Obviously no one can risk using high power weapons inside an FTL ship so these troopers are armed with close combat and low power weapons. Design invasion ships which have a detachable drive section. (In fact all ships should have a detachable drive section.) The ship jumps into orbit of the planet, scatters boarding pods and orbital assault platforms and jumps away. The boarding pods start to deal with any defending ships. Once these ships are destroyed you can begin landing troops. A first wave of troops in boarding pods/drop pods. A second wave of heavier equipment once you have cleared landing sites. It won't be long till new orbital defenders arrive from a nearby planet, but you're safe from orbital bombardment, you can never be 100% sure of avoiding detonating a drive. The ground war begins. Blade against blade. [Answer] Unfortunately I agree with the others, the outcome you want isn't what happens. What happens is that every ship you own is retro-fitted with auto pilots (or skeletal manned suicide crews) and charges for enemy homeworlds to kill them as fast as possible before they can come up with the same plan to use on you. The entire enemy empire turns into a fiery ball of gas. 25 parsecs radius is an area 150 light years across. That's a pretty damn big empire turned to dust. In the meantime you shut down all non-military traffic in your own systems to try and prevent similar chain reactions in your areas. [Answer] Lets summaty what we know. Techonogy used to create FLT engines, can be used to create ultimate weapons, and both empires have them. I'm not history expert, but this sounds very similar to situation between USA and Soviet Union. Both had ultimate weapons (nuclear arsenal), there were huge tension between those countries. But there were no actual war (at least not in standard way of thinking). I believe this will be similar in your case, both empires probably will sign agreement of not using this weapon, and both sides will be avoiding direct conflict as loosing side can lunch deadly missile any time. You will have bunch of covert operations, propaganda, both empire will try to organize revolution or ignite civil wars on planets which belong to other empire. [Answer] From what you are saying, your ships are the equivalent of themonuclear-tipped ICBMs with guns and armor strapped on them, and no one would want to start using them in actual battle. I will disregard the lack of MAD in the requirements, because the first thought any sane man would have would be to turn such destructive FTL devices into untrackable strategic weapons that can devastate an enemy (Since FTL detection is not mentioned). Because both empires would both like to survive as long as possible, I believe they will take up a stance similar to cold-war era Earth, namely using these ships are weapons of deterrence. If they have smaller neighbors, they may try to convince them to fight wars on their behalf, offering their large cruisers and capital ships as motherships that can bring a proxy empire's conventionally propelled fleets into a theater of battle, and remain on alert there just in case armageddon is required. Conventional battles can still be held, with formations of conventional warships engaging eachother with whatever weapons they have, until they can beat back enough of the other side's forces for them to retreat to the mothership and jump away. Or, to reduce the chances of a world-ending war, the motherships may only jump in for long enough to launch the conventional fleet and jump away, leaving the fleet to its own fate. Both empires would also probably engage in FTL tracking research, or if possible, FTL interdiction, which would allow some of these fleets to be pulled into uninhabitable places, where destruction is not of much concern. The main form of war directly between the two are not going to be "hot" wars, but rather wars of espionage and diplomacy, trying to make sure that when a first-strike is needed, that they are going to get that first-strike. [Answer] I'm going to try to stay in question parameters as much as possible. So we operate under the assumption that MAD is not an official policy; the FTL drives in question must continue to be used; everyone has them; nobody wants them to blow up again; but each empire still feels the need to be at war. I will assume that the FTL detonations make the planets effectively uninhabitable, if anything by destruction of any existing atmosphere. Any new operations on those planets will be done as if in a vacuum. Even without MAD, warring nations always adopt a set of Rules of Engagement. Effective immediately, FTL jump ships would be designated off limits. In order for this to work, every single FTL warship would be disarmed as quickly as possible, in an effort to prevent the need or the desire to open fire on an FTL ship. War is won based on the ability to take and hold an area, in this case, an area of space. As of now, there is effectively nothing to prevent an FTL ship from entering any area of space, anywhere, at any time - but they are unarmed, technically. And the non-FTL ships could take weeks to months to go anywhere in system. We now have classical invasions to fend off. Holding planets will become the more important task for the warring nations. FTL drop ships will enter orbit and start unloading combat forces into the atmosphere; flyers will be under fire from the equivalent of anti-air defenses attempting to prevent the attacker from gaining air superiority. Ground forces will be fielded in an effort to establish staging areas and combat fixed defenses. And they will be met with whatever modern technology has to offer in the way of soldiers, sailors, and pilots. Since the FTL ship is off limits, the invader now has a problem - being the aggressor on a new planet has the problem of bringing down an overwhelming defense response from other FTL drop ships within several light years. The defender has a similar problem - sending every drop ship he has in response to a threat runs the risk of having fallen for a diversion. For a little more perspective on this, communication lines can be jammed, false information passed, and covert operations can take place on essentially every planet that manifest in ways not unlike terrorism. Economy and manufacturing become more important than ever - virtually every single planet now has to able to field a significant, workable defense force to increase the available time before the fleet can respond. And depending on what else is going, they may never actually respond. [Answer] One thought i have not seen in any of the answers is removing the FTL. You already state that the FTL has limits and cannot function around large gravity fields. Equip your ships with gravity generators. Empire A ships jump to system full of Empire B ships, activate there gravity generators disabling everyone's FTL then open fire. Empire A is confident the no catastrophe will happen so can attack freely, Empire B will realizes they cant run and will stand an fight learning that they can now destroy ships safely. After a few skirmished and a major engagement Empire B will have the gravity generators. Spies, necessity of invention, already working on it just slower, they will find a way. Otherwise Empire A decides where and when the battles occur so will always have the advantage. A logical evolution would be to create independent gravity generators and use them a mines. Wars always ignite arms races, Mass reducers, anti-grav plating, void shields or simply better FTL drives can be applies as your story need them each with there own restrictions. Mass reducers can only reduce mass by 20% making them useless on anything bigger than scouts anti-grav plating reduces standard armor making ship more combustible but without other to chain react with only harm themselves when destroyed power requirements of void shields make them inoperable on anything below dreadnought class ships gravity resistant FTL - electric cars exist but most of us still fill up with petrol, takes time to filter down. essentially it removes the FTL explosion event so normal warfare can take place. [Answer] I think the war is the least of both sides concern. If the only mode of transport has such a drawback then potentially every single ship equipped with an FTL drive is now a huge liability. The moment news of that situation breaks out, commerce and all travel between systems in both empires will grind to a complete and total halt. Mass panic would tear the empires apart from within. No planetary leader would willingly allow an FTL capable ship anywhere near their own planet, and likely not even close to the solar system at all. The companies that make such ships would be torn apart by their own workers in fear. Essentially these empires would break apart into solitary systems. Hopefully the planets within each system are able to be self sufficient. The ones that aren't will die. That one shot and the explosion which followed would be the death knell of both empires and certainly society as either know it. So, the war would end. Not because either side gave up, but because neither would be capable of prosecuting it. [Answer] The reason the FTL drive exploded is because it is a hyperspace type, except that this one has a permanent breach in space-time instead of temporary rift. if so, they can operate near planets, don,t wanna destroy. logical? This would lead to interesting strategies, the ship with FTL and generators that warps close to a star and warps out releasing catastrophic stress on the stars geomagnetic stability. interdiction would be key. I do like the idea of the mothership carrying not FTL ships. ]
[Question] [ In an alternative earth, or just a few decades from now, someone was able to make a breakthrough in nuclear bombs. Developing a way to make the radiation be nullified by its extreme chain reactions or just dissipate it so quickly that the exposure to the fallout is almost inoffensive). The today's world accord on thermonuclear weapons ban is basically done due to the cheer amount of destruction and post-destruction the blast and the fallout would cause. A literal apocalypse that would cover the skies in ashes and lethal radiation. But, the second isn't a problem anymore in this scenario. Thermonuclear bombs are now "safe" to use. I know that even though they don't kill everyone with the fallout, they still have the potential to send the entire civilisation back to the iron age. After all, we have a pretty delicate infrastructure in the entire world, and so, these would be the first targets of any country. And the resources available are only obtainable using modern technology. So, taking those things in consideration, do you think this pact of non nuclear aggression would still be applied, or they would just press the button and send everything to hell? [Answer] The answer probably isn't as exciting as you'd hope. The world pretty much as it is now. Military generals have wanted the real-life answer to this question. As such, they commissioned military scientists to create exactly this. The result: The Thermobaric bomb. It gives an explosion just shy of a small nuke but a cluster of 20 of the FOAB (Russia's biggest Thermobaric) would yeild a 1 kiloton blast. (Even 1 FOAB forms the beginnings of a mushroom cloud.) That means the Thermobaric is capable of destruction that can compare to a nuclear blast. On the flip side, they can be reduced in size to a very small size as well. Thermobarics are generally used at smaller than their max size. This is because militaries prefer surgical strikes rather than massive strikes. (Testing the latter is good for intimidation, but that's about it.) Because, as far as pure destructive force, like nukes, there's enough thermobaric weaponry to render Earth unlivable. We just don't use it because the Earth can only sustain so many blasts before our atmosphere becomes deadly from just the dust. So the amount of explosions in the world has to be fairly limited to keep humanity alive. To put in a different perspective: Earth and humanity all together acts as one super-organism. And you can only hit yourself with a crowbar so much before you die.Sure, if your leg needs amputated, that's worth considering, but using amputation each time you get an itch is a short-path to death. [Answer] **Construction Nukes** If they were clean, nukes would be used for construction. Dams could be built, rivers relocated, mountain passes created. [![enter image description here](https://i.stack.imgur.com/bxy8M.png)](https://i.stack.imgur.com/bxy8M.png) [Lake Chagan](https://www.amusingplanet.com/2014/03/lake-chagan-atomic-lake-filled-with.html) was created by the Soviet Union using nukes for this purpose but the radiation wasn't understood properly and they got left with a lake nobody can use. A politician who claimed it was safe went for a swim in it and died of cancer a few years later. [Answer] # Everyone declares war on everyone else. All jokes aside, ultimately clean nukes probably won't change the equation much. Without the possibility of turning the world into a radioactive wasteland, it would seem like the use of nuclear weapons would become more politically acceptable, but... Thermonuclear weapons are actually extremely clean (relatively speaking) and won't generate radioactive fallout if the fireball doesn't touch the ground. The Tsar Bomba test was actually one of the cleanest nuclear weapons ever detonated (that of course would change if it was detonated at its full 100 MT design yield). Purely clean fusion bombs that don't use a fission primary are a theoretical possibility and have been researched heavily, but there are still engineering challenges that remain. Most theories involve muon catalysts or explosive pumped magnetic fields to compress the fusion fuel. If the USA, Russia, or China *did* succeed in creating such a clean weapon, it's unlikely they would be public about it to avoid triggering an arms race or create tensions that could lead to a preemptive attack (after all, radioactive fallout is the main political problem surrounding nuclear weapons, even if it is a red herring). But at the end of the day, it's unlikely that even if all sides knew of and had these clean nukes that things would change for one simple reason: Mutually Assured Destruction. MAD actually works quite well when state actors are rational, as is clearly shown from the Cold War's lack of an actual nuclear conflict. Clean nuclear weapons are still devastating nuclear weapons, and a full on assault between two nations would still leave them in tatters within minutes, so the deterrent effect, which is what nukes are really designed for, remains, even if the nukes are clean. However, what is a ***more*** dangerous proposition is if all nuclear weapons were magically removed from the planet. This is the true "*Everyone declares war on everyone else*" situation, as it returns us to a situation where wars between great powers become winnable. The USA, Russia, and China would be far more likely to get into a conventional war knowing there was no possibility for it to go nuclear. Similarly, smaller states without nuclear weapons might be more tempted to take on larger states with them, knowing that the possibility of mass casualties from nuclear attack no longer exist. Ultimately, it is the destructive capability over time states can bring on each other that acts as a deterrent. This is very evident in the situation on the Korean peninsula. Even without nuclear weapons, the fact that Pyongyang can absolutely devastate Seoul with artillery attacks has been a major deterrent for action from the South and the USA for decades. The fact that North Korea has been able to produce nuclear weapons is more for allowing it to force concessions out of world powers (after all, you can ignore artillery on a border that is ineffective beyond 30 miles or so, but not the possession of deliverable nukes that can destroy cities on a global scale). There is also the prestige of being a nuclear power, as evidenced by the joke: "What do you call a country with nuclear weapons?" "Sir." [Answer] You build nuclear rockets because nuclear rockets literally rely on a nuclear explosion to operate. The technology may or may not be applicable to conventional nuclear reactors since those rely on a controlled reaction and not an explosion, but if it is applicable, you build those too. [Answer] You're the author - **what do you *want* to happen?** If you want the status quo of MAD to be maintained, [stix's answer](https://worldbuilding.stackexchange.com/a/199767) gives a good argument that it could be. **If your story needs a world without MAD** clean nukes will be a good start, and with a few other elements in your alternative history you could come up with a plausible explanation. There's quite a bit of cold war thinking asking whether you could have a "limited nuclear war" - which was an important question if, say, the Soviets invaded France with conventional forces that outnumber French forces ten-to-one. Could France use nuclear weapons only inside its own borders, or only against military targets within a certain distance, or only weapons of a certain size, without triggering the end of the world? Their conclusion was 'maybe' - thankfully, they didn't test that. What you need to do is remove the dividing line between small nuclear weapons and large conventional weapons. * Part of that will be in public opinion: You need the clean tech from the start, so a dread of nuclear weapons never develops in the minds of the public. * You'll also want your clean weapons to be so clean that, other than the size of the explosion, they're almost indistinguishable from conventional explosives. * Then you'll want an established precedent of small nuclear weapons - nuclear artillery shells, for example, barely more powerful than conventional shells - having been used in war. Maybe they're also used in civil construction projects too. This way, it'll be a lot harder for MAD to develop into a stable system: Instead of having a clear line ("any nuclear attack") the line would be much fuzzier - inviting both sides to test one another, edging nearer and nearer to destruction. [Answer] Nuclear fallout isn't the only reason MAD deterrence exists, the non-fallout related destruction caused by the explosion is immense on its own merits and would likely still prevent war-like engagements. The other factor to consider is the amount of power these capability gives nations the USA might not agree with on various terms (such as Iran and North Korea). It's likely the main reason these armaments are sought after by these nations is to be a power broker and as leverage against other nations. We don't use generally use our highest caliber weaponry now-a-days anyway. The nuke would still be a viable weapon without the fallout for any nation's arsenal. War is just another political / diplomatic tool. Another consideration is the type of energy negation we're talking about here... Fission bombs are different than fusion bombs and emit different types of radiation at different levels. [Answer] # scientific breakthrough The **radiation shielding** has many useful applications: * nuclear powered cars * nuclear powered rockets (practical space travel in the solar system) * small (maybe household) nuclear plants (might fit in a dystopian world too) The **technology** used for that might also have a dozen applications: * better solar panels with 100% absorbtion rate * spy planes absorbing all radar pulses * total heat shielding (just got reminded of Asimov's *David Starr, Space Ranger* where the hero has similar tech) The **science** behind it might also have other tech uses, depending on how you explain it: * cheaper / smaller semiconductor technology * more efficient energy storage * quantum computing * FTL travel * FTL communication [Answer] **No More MAD** If you mean no radiation also removes the electromagnetic pulse (EMP), then that changes the entire equation for warfare. One is left with catastrophic blast damage but no direct effects outside the bombed area. Smaller nukes then start to look like big conventional explosions, and the threshold for using nukes would be reduced. A recent article in the Bulletin for Atomic Scientist places the risk of nuclear war at about 1% per year. If you are young, that means you will be at a 50:50 chance by sometime in your later years. You would never know this from our journalists and news media. In their quest to "sell soap" they focus on sensational matters, most of which are trivial compared to nuclear war. Recall that the media was discussing Gary Hart's love boat when 911 occurred. Your "no radiation" scenario probably would have meant that the Cuban Missile crisis would have gone off. We would have used small nukes in Vietnam. Someone might now take out the Iranian facilities. Your scenario is scary. An interesting caveat is that some of the targets for your radiation free nukes would release radiation: nuclear power plants, isotope refinement facilities, etc. ]
[Question] [ I have a sci-fi world that is very technologically advanced (at the stage of "sub-singularity" where they have already invented AIs posing danger to humans, but not achieving singularity, so it's not God-like and can be fought etc.). Both humans and the machines (so far the only inteligent "races") use technology. I want to specifically concentrate on the human technology regarding displays - are there any advantages, and could there be any advantages to use Cathode-Ray Tube displays, i.e. on a spaceship, despite the general inferiority of such display to LCD or plasma. Of course the old cathode screens "sucked" in their flickering, glitches, and image quality. But could there be some reasons, why their use would still be a good option to consider. Particularly in the military-utilitarian uses (similarly to how military planes and civilian planes differ) or industrial uses. I was thinking about potential costs. Could it be that on some planet the cost of producing the liquid-crystal display is to high, because of material shortage? Could there be some other advantage to CRTs? Are they used anywhere right now in professional industries, for other reasons than "not yet replaced"? I want to stick extremely true to physics as well as present a reasonable, believable future (meaning no "laser guns" shooting visible "laser bullets", no "telekinesis", at least without a good, scientifically correct explanation for it). But I also want to world to be consistent in terms of economy (at least to some point), people's choices etc. So if there are to be CRT displays, they need a reason to be there. Finally: why do I want to include them? Cause I like the glitch effects, and generally their style. Already military ships will use terminal akin to the ones often used in linux systems - but this isn't "forced" retro, because I personally believe that the terminal is the best way to use a system ;) Anyways I can find justification for a military spaceship depending on an old-school terminal interface instead of some "touchscreen" stuff, but cannot find justification for using CRTs instead of LCDs. EDIT: Thanks for the current answers, but I'd like to mention that the world I am describing is "our" world a number of years in the future. Interplanetary flight IS possible, common and even somewhat easy (the technical explanation for this exists, but I shall not go into details here). However we have to take into account the current human achievements, so LCD is or at least has been known. I guess it could be possible that some factory on planet XYZ which produces spaceships, got very very old design, and copied it. Or maybe the machines (which are quite a diverse, and active race) have been designing the spaceships for humans, but downloaded the easiest to find blueprints? [Answer] Ease of manufacturing in the field. Any vessel operating far from home needs a way to deal with repairing damage and replacing broken or worn-out parts. Sailing ships carried saws and axes so they could cut down trees to repair the ship. Modern military ships have machine shops and welding shops to manufacture parts in the field. A spaceship operating for extended periods away from home and help is going to need a way to replace anything which is essential to running the ship--either by carrying spare parts or by having the means to manufacture parts when needed. This would naturally include the computer hardware used to run the ship. Manufacturing LCD or LED panels is a ridiculously high tech process. The process involves large amounts of water, exotic chemicals, micro-scale wiring and glass etching, and bonding together multiple layers of materials. [This page about LCDs](https://en.wikipedia.org/wiki/Liquid-crystal_display) discusses how they're made, and it apparently [took the industry until 2007](https://en.wikipedia.org/wiki/Liquid-crystal_display#2000s-2010s) to produce LCD panels with better image quality than CRTs. [Cathode ray tubes](https://en.wikipedia.org/wiki/Cathode_ray_tube) on the other hand are much simpler and easier to manufacture. The first tube capable of displaying an image was produced in 1925, and televisions using CRTs were on the market in 1934. Color CRTs and color television was available by 1954. A spaceship which needs to operate without resupply for long periods of time may find it easier to carry the equipment to manufacture CRTs than more advanced types of displays. [Answer] CRT's are analog. If humans start seriously worrying about the loyalty of the digital world analog might be valued. And there are a lot of rants about potential analog advantages available. CRT's are human serviceable. You can trace wires, manually inspect the parts and hand solder fixes. If people are worried about long term supply issues that might be important. CRT's can be repurposed as boat anchors, space heaters, rayguns, tape-blankers, and magnetic field detectors with minimal work. If you are expecting to scrounge post-AI CRT's give you good options. [Answer] **Racism.** Cathode-ray displays flicker. Humans see them correctly because they are kept at a refresh rate that is good for humans. Other species may have lots of problems. Different species have different flicker thresholds. What looks like animation for us may look like a strobe to other races. Also robots and cyborgs may run at a specific frequency. To them the image could just be a dot. So it could become a class system. People with expensive high speed visual implants can see CRT's but anyone running at around 60 hz can't. So the rich get crts to show off. So why do it? So you could watch tv yourself. Put on some headphones and watch that screen. You are rich. And now your servants won't be distracted by an image they can't see or is unpleasant to look at. Also they can't sneak of from work and watch TV if it all looks bad. Maybe when in a way the enemy can't see your instrumentation either. [Answer] ## Vector vs raster CRTs can implement one of two display technologies: * A *raster* display, which is scanned left-to-right, top-to-bottom, to produce a fixed grid of pixels set by the sweep timings. * Or a *vector* display, where the image data is fed in as a set of instructions that both govern the sweep of the electron gun(s) and their intensity. LCD and OLED displays, though, are inherently raster in nature by virtue of being assembled from discrete pixels. This means that a technological society that embraced native vector display wholesale would have a much tougher time migrating away from CRTs than we did, where most of our mass-market CRT usecases could be readily migrated to LCDs because the display model used was no different. [Answer] The only real pros of CRTs against LCD or LED, are CRT do not have a native resolution, they will display in pretty high quality up to their maximum resolutions without requiring any form of scaling and therefore the GPU of the computer can maintain a fairly high FPS, this is why when LCD first came out a lot of gamers still used CRTs, (that and we tended to spend our money on better GPUs rather than screen) however as price was a factor in this and that has since come down so significantly and GPUs are far better these days that this pro has been effectively neutered. CRTs are capable of true Black, a total absence of light, LCD and LED have black lights so the contrast between darkness and light on screen has to be set as a standard, wheres CRT simply do not emit light in the dark areas so provide basically perfect contrast, however OLED technology has now eliminated this benefit. Dead pixels, CRTs don't get dead pixels, they can lose an entire tube but this is immediately obvious, whereas an LCD or LED screen can suffer from a dead pixel that will simply not show anything... Basically, there's only those three reasons to use CRTS over and LED or LCD and about 20 reasons to use LCD or LED over CRT... its gonna be a tough cookie to sell Maybe... they didn't have Hollywood? maybe Films and TV never progressed well on this alien world, without these driving factors, colour screens would not have been so readily required, so black and white screens were the main thing, if all the people wanted was Black and White at high quality then CRTs would be perfect for it, not point in an LED screen if all they need to do is light up white every time... in terms of price... CRTs use glass and electrodes, not much else, LEDs use the same elements but also use gallium arsenide (GaAs) and gallium phosphide, so if Gallium was very rare, that might affect its use, however Gallium is used in semi-conductors all over the place, and is a very useful element, so that might affect the world in other ways. [Answer] CRT is essentially a vacuum tube on steroids. While it took us a long time to develop LCD technology, at its core are liquid crystals. The *modern* LCD use LED for backlight, a solid-state semiconductor technology. Do you see already, where I am going? Let's heal a headache with decapitation! # No silicon-based electronics And also no germanium or gallium arsenide. Transistors were never invented. Diodes are still regarded an esoteric technology part from early radio days: detector radios are just as primitive as *camera obscura* and just that far from the real modern tech. While LCD is strictly not a transistor-based tech, it became practical in the integrated circuit era. The major benefit of LCD (even with non-OLED backlight) is its size. You don't really need to spare on size, if your devices are not portable anyway. So, just follow the tube-based electronics *ad absordum*. People still built TVs and computers with it in *real* history. So, things like "let's simulate an earthquake or an A-bomb explosion" are still feasible. Things like "let's give almost everyone a portable device with computation speed of a decade-old supercomputer to look at pictures of cats" are rather not. Already in our history people got quite creative with tubes. Tubes in metal hulls. Mini-tubes. Tubes almost as efficient as easy as *early* transistors. You microwave is most certainly still tube-based deep inside. Unsure, if PCBs exist, by the way. While early tube design surely did not have this, in the later years people indeed used some circuit boards. This could habe been the transistor influence or indeed a genuine development. People generally get very creative with a technology piece, especially in absence of alternatives. So, expect a lot of creative usage and miniaturisation of the tubes, but not "transistor revolution" and also no "digital revolution". Those elsewise poor folks also happen to have a much better and *nicer* sound, if you ask audiophiles, but I digress. --- Byline: The whole solid-state electronics was missed by this version of humanity. Or even the physics in that world does not work this way: tubes work, transistors don't. *(Doubt.)* Anyway, they don't have LCD display, because CRT is enough. Because it's impossible to pack a single computer in less than two racks. [Answer] # Security (sort of) Information leaking from CRT is different, and in several ways more jumbled, than that emitted from LCDs. There might be ways of tuning to the Van Eck emissions of a LED panel and reasons why it was easier than with CRTs. Bringing the concept to its extremes, most if not all light-emitting diodes (being powered by quantum mechanical processes, which means they're magic) could turn out to also give out a distinctive, non-electromagnetic handwavium radiation that is almost impossible to shield, that allows detecting ships in space. LEDs are therefore used, but as communicators. For security purposes, all lights and screens on starships are lightbulb or CRT powered, giving them a distinct 1960 air. # Resistance to radiations Semiconductor screens cannot be shielded, since they need to be *seen*. But this exposes them to radiations that will in time degrade their performance. # Both If the enemy has advanced electronic warfare capability, then you want to have the dumbest electronics that will do the job. Whatever cannot be reliably shielded from outside hostile signals (and monitors can't) must be physically unhackable. In [*A Fire upon the Deep*](https://en.wikipedia.org/wiki/A_Fire_Upon_the_Deep#Plot), the Blight - a super-advanced AI - is able to penetrate a ship through an overlooked laser sensor, and have it self-destruct. If you meddle with rogue AIs, you probably want pilots having mechanical watches and looking at dumb CRTs. You might actually *need* that. [Answer] **Hacking** In the first skirmish against a rogue AI, we learned that we can't trust our monitors. As you know spaceships don't have windows, we depend only in our screens and sensors. Just using a few small commands, they blinded a whole group of fighters. For that reason we had to go back to our roots, they can mess with our touchscreens with ease, but an old CRT is inmune to those kind of attacks. [Answer] In opera and musical theater all analog signal chains are used for a live "conductor cam". Any use of A2D or D2A converters along the chain will cause lag. Therefore big old CRT TVs are used for the monitors, otherwise the screen view of the conductor's baton will be considerably behind the actual beat. Analog security cameras must be used too on the other end. Not sure how this could apply to your Sci-Fi world, but it is definitely an example of a current professional use for a reason other than "didn't replace it yet". [Answer] I can imagine an answer that is similar to the question of why we're still using fossil fuels when better alternatives are available? The answer is simply because their society is addicted to them. They have an industrial complex that benefits from maintaining the status quo (because it means continuing demand for the product without needing money to be spent on developing anything new) and has the political power to keep the world from moving to different technologies. The longer this scenario continues, the harder it becomes for new technology to emerge, because the little competition that does exist between manufacturers means that the CRT technology does develop and becomes highly refined and extremely capable, to the point that even if someone did try to develop an alternative display tech, it would take a long time before they were able to develop it sufficiently to compete with the established players, and the cartel could very easily close them out of the market entirely. In the real world, LCDs had the killer advantage of being flat, low energy and lightweight. Early LCDs certainly couldn't have competed with CRT TVs, but did make excellent watches, calculators and handheld game machines. This gave them an entry point to the market, from where they could continue to be developed. You need to imagine a world where the CRT makers are powerful entities, and feel threatened by the emergence of LCDs, even when it's just being used for calculators, and are to cut off the development of the tech by whatever means they can. Why would they feel threatened by it and try to kill it? In the real world, if they're that rich and powerful and they see it as a promising tech, they may want to buy it instead rather than bury it. So in your world, there needs to be a reason why they would react that way. I don't have an answer to that bit, so I'll leave you to ponder it. [Answer] CRTs are heavy, draw a lot of currant, take up a lot of space and no it would be impractical to repair the glass tube that is under a vacuum and the display face is covered in phosphor. For the mass of all the equipment to attempt a repair of the tube you could carry many spare flat displays. We are talking about space craft that will need to break free of gravity. Saving mass and space in the craft is important. Then there are the health and safety issues. The electrons from the gun do not magically stop at the display surface. They continue on to the operators eyes and cause cataracts. I worked with Air Force Radar and have had to have both my eyes operated on. Since you have this glass vessel under vacuum you have the implosion issue that will send out a shower of broken glass shards if there is an incident. Then there is the high voltage that is required to operate the gun and electron beam steering. Lastly these displays are easy to shield from emitting signals since we are dealing with smaller voltages. There are conductive fabrics that are see through that will keep any signals from escaping the face of the display. Think of woman's stockings. Just my thoughts, thanks [Answer] It's hard to see why; there's the matter of weight and size and power, which would be a factor for spacecraft or aircraft (since you're keeping it realistic. I'm typing at a desk with two 27" monitors, massing a total of about 7 kilos (not counting the mounting arm): the equivalent screen size in CRTs would be about 63 kilos. The two flatscreen average a total of about 42 watts of power in operation combined; two equivalent CRTs would be 150-200 watts combined. The flatscreens are only a few centimeters deep allowing mounting pretty much anywhere, while the CRTs would need almost a half meter of space behind the screen. And it's easier to make arbitrarily sized displays (as long as you're willing to pay). You want a monitor 3000 pixels wide and 100 pixels high for some stupid reason? Flatscreen tech can do it, a CRT not so easily. There are some applications (such as showing true black) where CRTs might have a slight advantage, but it's not going to be that significant a demand. [Answer] Cathode ray tubes arranged as displays for seated humans will irradiate the testicles of the males with Bremsstrahlung X-rays, which radiate perpendicularly to the electron path as it impacts the glass at a speed in excess of the speed of light (in glass) causing genetic damage and reducing fertility. You can be sure that advocates of this solution are either AI instances or Russian subverts. ]
[Question] [ I'm writing a realistic sci fi story involving interstellar conflict , where space warships (assume something like star destroyers from star wars) are the norm, These warships are capable of orbital bombardment and can essentially strike any place on a planet with immense force and rapid speed. In such a situation, would a traditional army and navy even be necessary? A single spaceship could wipe out an entire navy or army easily from orbit with no losses, which I feel makes them redundant due to the immense disadvantage. Would it be better to instead only have a group of elite marines to deploy from orbit to occupy objectives and perform delicate operations instead of keeping around a big army and navy to fight wars on the surface? I would like to have futuristic land and naval battles but I don't see how that is possible when a spaceship could just wipe everything out. [Answer] Space ships are like aircraft. They are very good at projecting power, but they are less good at things like gathering intelligence or holding indoor positions. A spaceship or aircraft can knock down a building, but it takes a person to take it more intact. It takes a person to protect people on the ground that you *don't* want to kill. So, unless you're sterilizing a planet, if you want to subdue, not exterminate the population on the land surface, you'll need an army. The same goes with a navy. If you're trying to control the sentient population of the planet on or under the water, unless you want to just kill everyone and everything, you're going to need tools capable of more finesse than an orbital bombardment. Sure, aircraft can prosecute attacks against ships and submarines - when they can find them. A ship or a submarine can be better at finding other ships or submarines than a spaceship. [Answer] You can bombard as much as you want, but until you are not able to set your boots on the ground and hold them there, you will not be controlling a piece of land. Look at the most recent wars, like operation Desert Storm or the various operations in Afghanistan between 2001 and 2021: air supremacy and capability of destroying at will is one thing, having troops on the ground capable of actually controlling the territory is another. Same will hold in your scenario. You can orbital bomb as much as you want, but with no troops on the ground to occupy it, you will not control anything. You still need army and navy. [Answer] I don't know if this should be a comment rather than an answer, because what I really wanted to say is "your question needs more details or clarity". Why is that? Because I see you start for the common, but unsubstantiated, mindset of "a spaceship on orbit will have the upper-hand over ground forces", which is something coming from Star Wars-like space operas. There is absolutely no reason why your story has to follow that convention, and if you want to be original, you maybe shouldn't. Why a spaceship orbiting a planet has advantage over the surface forces? For the same reasons Obi-Wan Kenobi had advantage over Anakin Skywalker by being on higher ground: plot reasons. Or in other words, no reason at all. The supposed advantage of orbital control is assuming that the forces on the ground cannot hit you, but why that should be the case? Sure, the USA in Afghanistan or Israel over Gaza have a massive advantage through its air force... but this advantage is just the enemy having no anti-aircraft weapons. In a war where both sides have strong anti-aircraft capabilities, such as in the Russian-Ukranian war, the idea of air force as an infallible way to victory is contested. Supposing that your enemy planet is not some backward shithole whose civilization is still at early bronze age, the idea of superiority of orbital spaceships is highly disputable. There are just two possibilities: your story takes place in a hard-scifi setting, where those ships have been probably been built in space because it's too hard sending all that weighty mass to space, and they move through the old Newtonian third-law of forces, expelling some kind of propellant to create a change of velocity, or it's a more soft-scifi approach where antigravity devices or similar methods of propulsion are in place. In the first setting, the spaceships in orbit have the advantage that it is very difficult for the planetarian defense to hurl things up against the planet gravity well... but the thing is, they don't need to launch a lot of mass to destroy the spaceships. Any ICBM will do. And your spaceships are sitting ducks while in orbit. Their trajectories are predictable, and the maneuverability of those huge ships must be extremely cumbersome. Basically, you're an old WWI battlecruiser chased by modern fighter jets. In the second setting your spaceships are allowed to have much more maneuverability and speed thanks to these non-newtonian technology... but so are your enemies. With artificial gravity, there's no reason why a planet cannot have armored spaceports where their defence fleet lies, and they can get to orbit to fight your invading fleet. Every time that the trope of "orbital superiority" arises is because its advocats are assuming that they can bomb the planet at will, while they can't be hit from the planet. Unless there's a significant militar imbalance between attackers and defenders, that needn't be the case. [Answer] ## Why do we have armies and navies now? [![Nagasaki Mushroom Cloud](https://i.stack.imgur.com/d8cYJ.png)](https://i.stack.imgur.com/d8cYJ.png) Even without a space force, there are at least 2 powers on Earth that could strike any army or navy deployed anywhere on the globe and several others that could do so on a regional scale. Yet all of those maintain ground, air, and seaborne conventional forces. Why? 1. [MAD](https://en.wikipedia.org/wiki/Mutual_assured_destruction) - if you can do it to them, they can do it to you. 2. [Genocide](https://en.wikipedia.org/wiki/Genocide) does not play well in the media. Even if you are totally impervious to the enemy's retaliation, there are likely to be elements of your own society as well as neutral third parties who are uncomfortable with total planetary destruction. 3. [Occupation](https://en.wikipedia.org/wiki/Military_occupation) - so you're OK with genocide and you don't fear retaliation, maybe you want to occupy the territory (with or without the native population) without having to rebuild flattened infrastructure. [Answer] ### Submarines are hard to find and hard to destroy In addition to the need for infantry mentioned above. Do not underestimate the ability of water to keep things from being seen and absorb and dissipate most types of energy in large quantities. Submarines are very difficult to find without extensive sonar systems (which themselves kinda become a navy). And even if you've got a way to find them from space somehow, if they've dived it's going to take specialized weapons just to deliver fire on them. A laser or railgun is not going to penetrate and a missile will impact on the surface. Again meaning you need something a bit like a drone navy. [Answer] ### The navy is redundant/obsolete In your scenario, there's no need for a navy. The point of boots on the ground is to handle the interpersonal stuff (which will definitely include skirmish-level firefights, but will definitely also include establishing control over the civilian government organisation). Transport between places will be by aircraft or intercontinental spacecraft. Hell, even the navy today is no longer the navy of the days of battleships. The early 1940s established firmly that aircraft could kill any battleship with impunity, and sonar then let them kill any attack submarine with impunity too. From the 1940s then, the only role of a navy was to move aircraft around. The 1950s added the role of moving nuclear missiles around underwater, and the 1970s added the role of moving cruise missiles around. The navy has no other military raison d'etre. If you've got guys in orbit prepared to deliver Rods From God, all those roles simply vanish. [Answer] This always bothered me in star trek and star wars. You have ships attacking planets. Planets that effectively have unlimited power, unlimited shield, and virtually unlimited weapons. If you had a navy, they are going to have whatever space shields your space ships have. And they will be able to provide tons more power towards it because they don't need life support systems. In a more realistic setting, attacking a planet should be suicide. But let's take this a step further, why does a space ship need to shoot the planet at all? Fly out to the asteroid belt, and hurl one at Earth. With precise enough calculations you could hit the exact spot you want. So a navy might actually be more important in the space warfare age. Simply to make the target not a city or a place with a lot of civilian damage. If I can put my giant space ship busting guns on a navel ship, then of course I am going to do that. Any counter fire will land in the ocean. But let's now take this less sci-fi. You have a space ship, it fires a missile at the Earth. What do you do? Well the problem with intercepting missiles is we have to figure out where they are going. Usually we figure this out as they start their decent. Well your space ship can only shoot downwards. But does that affect anything? Not really, the missile is easily intercepted by a (much) cheaper ground or navel based missile. This dramatically diminishes the value of a space ship firing on the Earth. [Answer] When writing fiction I often try to look at reality, and it is a bonus if it is related to something actively happening now. > > There is a weapon that can completely obliterate the enemy. There are also weaker weapons that can kill some of the enemy. Why would the less powerful weapon ever be used? > > > Ukraine is fighting a war with Russia. Russia has nukes and Ukraine doesn't, why does Ukraine bother with having an army? I can think of a few reasons: 1. Russia doesn't want to use nukes (for fear of angering other countries) 2. Ukraine wants to be able to defend itself from other countries (eg. Belarus) that don't have nukes 3. Ukraine wants to use its relatively weak (ie. without nukes) military to police certain regions under its control. 4. Russia wants access to the Ukrainian controlled port. If Russia bombs it to ground zero, there won't be any port to use. Israel is fighting Gaza. Israel militarily overpowers Gaza in every way. Why doesn't Israel simply bomb Gaza and end the war? 1. Israel doesn't want to indiscriminately target and kill 2m Gazens. 2. Israel wants to rescue its hostages and not have them die of collateral damage. See if any of those reasons help you with your plot. [Answer] ## [Join the Spacy! See the World!](https://youtu.be/6k4vpmOobn8) Welcome the United Spacey! We look back on a long history of shipping, transport, and warfare, going back almost as far as the Army! We were the big stick of Roosevelt! At one point we used to be called the Navy, but with the advance of spacecraft, we rebranded into the Space Navy, short Spacey. We are the only ones who went with the time - [our carrier vessels ships swim **and** fly to the stars!](https://www.macross2.net/m3/sdfmacross/carrier-prometheus.htm) ## Join the Mobile Infantry! (Army) [Do your part!](https://youtu.be/jO1vWxUqpFI) Join the Mobile Infantry, get your ticket to the stars, and get your feet on another planet's soil! [Service Guarantees Citizenship!](https://youtu.be/jk-US71OV3Y) ## Welcome to the Planetary Defence Forces! You see those Spacy and MI people leave for war, never to return? Do your part here, right at home! Get your hands on the hottest and fastest interceptor fighters and blast those invaders to hell! [Answer] What are your **war aims**? Do you just want to kill the entire population of a planet? Then you don't need ground forces. Also, you're a monster. (Hypothetical you. If you're writing a story with monsters in it, that's fine). Do you want to kill specific enemies while harming as few of their innocent neighbors as possible? Do you want to seize infrastructure intact for your own use? Collect taxes? Enforce laws? Rescue hostages? Distribute humanitarian aid despite local despots who would prefer the population starve? All those things require ground forces. [Answer] The question fails to consider that the enemy also has a vote. Assuming a "Star Wars" type setting, a planetary system has the energy and resources to build a comparable fleet of spacecraft - indeed, by omitting the FTL drive it is likely that several warships could be built for the expense of one FTL warship. Gaining space superiority may not be anywhere as easy as you expect. [![enter image description here](https://i.stack.imgur.com/tZlDO.jpg)](https://i.stack.imgur.com/tZlDO.jpg) *Space battle as imagined in the "Three Body Problem"* As well, fixed defenses can also be built on planets, moons and asteroids, with the potential to be much more powerful than anything capable of being carried by a ship. You might find yourself fighting through a system with powerful ship killing weapons hidden away in many different places, unexpectedly exposing themselves and firing when you least expect it. Gaining a superior position in orbit will require a powerful battlefleet capable of fighting it's way across the Solar System - enemy squadrons backed by fixed fortifications and weapons will be waiting to oppose you. As well, while you may be capable of bombarding a planet into rubble, why won't the enemy try the same tactic against you? Your fleet might be better employed defending your planets than trying to attack another planet. Finally, your scenario is actually self defeating - if you can just appear in orbit and bombard the planet, then large scale political organizations like "The Republic" or "The Empire" have no real use for most people - how can they protect you from what are essentially Space Vikings from plundering your planet? Once the technology arises to allow you to do this, then eventually polities will disintegrate into single planetary systems, and upwards mobility will be either becoming space pirates yourself or launching hyperspace bombardment missiles at any planet which has the ability to make spacecraft capable of threatening you. [![enter image description here](https://i.stack.imgur.com/n2L6c.jpg)](https://i.stack.imgur.com/n2L6c.jpg) *Imagine these able to hit planets in other solar systems* Ground forces will still be needed regardless to man the defenses, control the population (or move them into shelters) and keep control of the territory. Some form of Commando or SoF forces will also exist to conduct raids against enemy systems, attempt to disable defenses and fortifications or act as forward observers for space-born weapons, which conventional armies will be needed to prevent landings or flush out landed units. [![enter image description here](https://i.stack.imgur.com/tRTsB.jpg)](https://i.stack.imgur.com/tRTsB.jpg) *Lunar Marines from the show "For All Mankind"* So your scenario is the trigger for disintegration of large scale political units, preemptive strikes against other planets and low level Commando warfare on the ground and in space in support of the larger weapons systems [Answer] ### You need more space assets to do what you want than you think Planets are big on a scale we don't really grasp. And orbital shells are mathematically required to be even bigger. Sure, if you only have a few brush fires a day you can divert your starship to act as overwatch and put munitions on target. But if you are fighting the population of the entire planet? Just monitoring is going to take a dense fleet of re-deployable satellites. Fighting?, that's going to take an enormous fleet to be able to reposition onto hotspots and hit them. And there's probably little reason to think that a spaceship isn't the *least* cost effective form of artillery out there. Using a lot of surface forces is just cheaper, maybe cheap enough to be possible, I assume you aren't using weapons of mass destruction because the only reason to bother with the planet is because you want it. If you just wanted to mine there are plenty of asteroids, so you probably want the biosphere. [Answer] It does not make sense to sort your forces like this in space. On earth they are sorted by medium moving through and distances covered / capabilities. In space there is inter-system, in-system and basically atmospheric/CQB as distinctive classes of forces. [Answer] "Why do we have soldiers when we have Battleships?" "Why do we have soldiers when we have Tanks?" "Why do we have soldiers when we have Aircraft?" "Why do we have soldiers when we have Nukes?" "Why do we have soldiers when we have Drones?" "Why do we have soldiers when we have super-duper-future-death-rayweapons?" When you read military history/argue in military history forums - this argument in some way/shape/form always rears it's head. All throughout Wars - there has been some general or other senior person who, *from a place of noble intention of not wanting to see young men endure the horrors of combat* has suggested that *insert superweapon* could replace boots on the ground (and sometimes because they have significant shares in *Superweapon manufacturer* but we aren't covering that today) And everytime this is discussed, someone - invariably from the USMC - stands up and says "The most dangerous Weapons system on the Battlefield is a Marine and his Rifle!" and then the commensurate 'OO RAHS!' from every Devildog in a 50 mile radius. Whilst it may not seem that way, there is a *lot* more truth in that statement that we would care to admit. Firstly - control of area - without boots on the ground, patrolling, projecting force, being a constant presence *and deterrence* - you don't control the area. That actually has a really big deal - think of the Ho Chi Mingh trail in Vietnam, think of the insurgencies we've seen - even with **massive** technological superiority, the enemy were able to effectively move Men/Resources covertly in order to be a PiTA. Secondly - Humans are really quite versatile and rather stealthy. Look at the Ukraine conflict with Tanks getting annihilated by small teams in well-prepared ambush locations. Even with top-tier surveillance systems, Humans can hide pretty effectively - buildings, tunnels - hell the USMC recently defeated an AI surveillance system with a bedsheet. Thirdly - Threat, *perceived* threat and target prioritization. So, you're in orbit with your super-Death-Ship - you see a massed formation of big metal things with big shooty things and you decide to unleash a phase-shift-thermo-torp at them. That'll show them! Then you see with your super-advanced surveillance systems that have crystal clear resolution a lone boy walking through the desert. Obviously not a threat - what could they possibly do? What you don't know is that said boy has a radio and has just observed the trajectory of your torp that annihilated the *decoys* that you just blew up and has radioed in your position to the surface batteries that were hidden and the next thing you know - you are playing a non-consensual game of 'who can survive in the vacuum of space the longest' In short - no Super-weapon ever replaces the need for maintaining control in a particular environment. [Answer] The thing with high science fiction is that if you can throw rocks from space, the planet can throw mountains back up. Ignoring that, there’s only one reason to use massed orbital bombardment: genocide. But this has many problems, namely your neighbors. In our current world we don’t nuke each other constantly because of reasons like “the people I didn’t nuke will likely not wait until its their turn to be nuked”. One thing people seem to forget is that the planet you orbital bombarded isn’t the only one, and everyone who knows you did it now has a good reason to do it to you until you aren’t able to do it again. Another real world example: when nukes were attained, the USA assumed every war afterwards would be a nuclear war and that regular army would not play a major role. Since then regular armies played a bigger role than nukes (exception for the threat of nukes over firing it). If what you want is resources, the buildings and infrastructure you destroy is some of the easiest to attain resources. Its a waste destroying it. Some people argue “ah but in Galactic timespans just waiting for a planet to become livable again is a small thing”. But when you compare the effort and energy of making the planet livable again against the energy and effort it takes to gain control of the planet and subsequently start using the planet (even if you genocide everyone and repopulate) then orbital bombardment is always a bad strategy. In short term timescales its also a bad idea to bomb everything… So the only reason to use orbital bombardment is either active genocide because you don’t care or limited scale orbital bombardments against specific targets so the planet remains useful. But a thing anyone does is prepare for war. If orbital bombardment is possible, armies will prepare for them. Bunkers, underground infrastructure for long distance transport or holding territory, shields\* (?), weapons to counter orbital bombardments, obfuscation of targets or decoys, defenses that prevent enemy space ships from easy targeting (and if fired from farther it gives a lot of time to intercept), placing military installations around things an attacker would want to keep intact etc. We haven’t even discussed space-based habitats. Its likely you have access to space habitats and even likely that a significant portion of the population is inside these. Capturing these will be more useful than destroying them, especially with potential Kessler syndrome denying you the planet (and any of your ships being instantly engaged by other parties if you get close, no one wants to risk getting genocided by maniacs shooting space-cities out of the sky). All this results in one thing: you will want an army. The type of army will depend on your strategic goals, current conflicts, threat of neighbors and available methods of arming yourself. But rest assured that armies will exist, and most armies will be used more than orbital bombardment. \*assuming you have shields, you don’t need vast powerful orbital shields. All you need is a shield with just enough power to create a shock to the orbital bombardment projectile and cause it to selfdestruct. Many small shields that can be placed in the path of projectiles would provide a whipple-shield effect and severely reduce the impact of orbital bombardments. The beauty of this is that things that move slower can easily penetrate the weak shields and still land. [Answer] # Mobile Planetary Defenses All of this answer assumes that both sides want to have control of the planet with minimal losses of civilian life and minimal destruction of civilian infrastructure. This also assumes a war between two multi-planetary political entities, both of which have FTL technology. First, think from the perspective of the defenders. Attackers may show up with a large space fleet around any of their planets. A defensive space fleet won't be able to respond in time. Thus, each of their planets need anti-space defenses. There will likely be space-based defenses and planet-side defenses. The challenge with planet-side defenses is that planets are at the bottom of their own gravity well, so energy weapons will fare much better than kinetic or missile weapons despite the atmosphere you need to shoot through. The trope approach of planetary based guns (ex. <https://starwars.fandom.com/wiki/Ion_cannon>) are bad because they are stationary, and therefore are easy targets for orbital kinetic weapons. Mobile planet-side defenses are going to be more effective. The easiest way to make them mobile (assuming sufficient water coverage of a planet's surface) is to have them be boats. Hence, a water navy would be an essential part of planetary defense. If the defenders have a water navy trying to shoot space ships out of orbit, the attacker isn't going to be able to stay in orbit very long. Thus, attacking a planet looks like the following: 1. **Space Battle:** attack fleet shows up and fights the space-based defenses while being shot at by the planet-based defenses. 2. **Naval Drop:** assuming the attackers win the space battle, attack fleet drops war ships to fight the defender's navy and attempts limited bombardment of key targets (such as any grounds-based anti-space defenses) before retreating. 3. **Naval Battle:** attacker's navies fight across the planet's oceans to try and defeat defender's anti-space defenses. 4. **Ground Battle:** assuming the attackers win the naval battle, the attackers now have space superiority. They now need to send in their army to capture enough key infrastructure points to get the planet to surrender. They also potentially need to do this before the defender's space fleet shows up to kick them out of orbit. [Answer] Summery of options for ground defenders. 1. **Orbital defence systems**: Sure your navy can blast/fight your way though them but its a race. The enemy will keep launching more more while your busy shooting them down. And planet 'big'/spaceships 'little' so their magazines will potentially be larger than yours. You might still win but it costs you time and effort. 2. **Global ECM & EW networks**. You can scan a planet optically from orbit but unless your EW systems etc are as good or better than the enemies a lot of the time your other sensors will at best be partially if not totally blinded. 3. **Fixed Ground based heavy weapons**: The fixed ground based systems can pack a punch as least as heavy if not heavier than your ship board capital weapons and they are well hidden (unless your spooks have done their job well). The enemy will hold them in reserve until your navy enters orbit and then fire them. They won't last long because once they fire they're almost certainly going to be detected but it doesn't matter. If one large ground based defense system destroys or badly damages one of your Star Destroyers it's a win net for the enemy because they can build what? 10/20/30/?) 'big guns' for the cost of your ship. 4. **Mobile planetary defense systems**: see submarines previously mentioned. Perhaps smaller and less powerful than land based systems but also much harder to detect and (relatively) more survivable. 5. **Optical fiber networks**: Your fleet 'networks' via photons traveling through a vacuum. These potentially be intercepted. Think of all those frustrating stealthed micro sats the enemy has deployed into Lagrange points and high orbits or perhaps even just automated listening posts on the local moon. The enemy however has a hard wired grid. Nothing to intercept or jam. Even mobile units can tap into the network when they need to. 6. **Manpower:** The planet already grossly outnumbers you. Whatever small % of its population it can in reality afford to employ in the military can leverage the high degree of automation the network allows into large manpower savings. It can automate it's fixed based defense systems so that they are 'manned' by very small cadre of human operators working from concealed locations. The entire planetary defense grid might only have a few hundred people operating it freeing many more soldiers for combat duty. Your fleet however still needs thousands of people just to say in orbit before it can even think about firing a shot or landing one pair of boots on the ground. 7. **Mobile ground combatants**: Soldiers, armored vehicles, supply chases and perhaps even robotic combatants all camouflaged and disbursed around strategical important locations just waiting for your marines to land. Again unless its a developing colony world they almost certainly outnumber you. **Conclusion.** You have the all important high ground which is invaluable if or when you decide to launch a ground invasion but its not a magic bullet. You only really have two choices. A long a expensive (perhaps decades long?) siege as you slowly wear the enemy down from orbit or you go down and take the place. Good luck. [Answer] ## Because inhabitable planets aren't cheap Repeat after me, kids: a reaction drive is a weapon effective in proportion to its efficiency. A drive powerful enough to enable somewhat-convenient interstellar travel is a *really* powerful weapon. So powerful, in fact, that it's trivially easy and cheap to destroy a planet. Unfortunately for the Ministry of Defense's pocketbook, while the *means* to destroy a planet is cheap, the planets themselves are quite costly. Terraforming exists, but it's expensive, takes a while, and the result isn't ever as good as a naturally-inhabitable planet. In the end, it's usually cheaper to just send in the Mobile Infantry. As a result, while space fleets can easily destroy planets, they mostly just use that capability against airless rocks with no civilian value. Limited orbital bombardments are used to support invasions of inhabitable planets, but the majority of the fighting is done by boots on the ground. [Answer] **A military is as much about defence as offence.** Effectively, you're wondering why keep a standing military when you have the nuke. The issue is nukes don't actually solve anything. If you start using one to vaporise the enemy, they'll do the same, and you'll both end up vaporise. If you want to actually takeover the enemy's land rather than leave it a radioactive crater, nukes are also subpar weapons. If you're defending your territory, you might prefer that it also doesn't become a radioactive crater. We could of course entertain the idea of keeping elite commandos to do those jobs of taking someone's oilfields and other assorted stuff. But then that can be countered by keeping a slightly larger elite commando force. The logical conclusion there is a sizeable standing military that will deter others from trying anything stupid and/or allow you to do something stupid. And I know this will anger military nerds, but a bunch of space marines is an army. Even if we operate with the assumption that you just have battleships and commandos, these commandos will need bases. By the time you account for all the infrastructure necessary to run these bases, you'll end up with a small army. You'll have commandos, yes, and training instructors, pencil pushers, MPs and JAGs, quartermasters, wrench monkeys, and so on, and so forth. Simply put, if you entertain the idea of tickling others on their turf, you're gonna have an army. You can call it something else, but it'll be an army. --- **Where there's ocean, there's boats.** A similar rational applies to a naval fleet. You're going to have fishing boats and yachts or other recreational boats, and thus you're going to have a navy that can bring the law to the high seas when necessary, and operate search and rescue missions, and other naval shenanigans. You could also use the opportunity to place a few submarines with ASAT weapons, and become part of your defence system. If you're planning on invade Earth from space, you won't need to bring a navy. But at home, you're probably going to have one. Maybe not a big one, but you're going to have one. --- **And other benefits.** As it turns out, having a bunch of people on payroll sworn to obey your orders as a few other advantages. You can order them to go risk their lives to save others. The US Coast Guards is a military branch. In a variety of countries, the military is called to help dealing with natural/industrial disasters. They can be trained to deal with such scenarios, however unlikely, and more importantly they don't have the option of saying "no way, I'm not risking my life for these shmucks who can afford a boat but not a life jacket". You can call on them to maintain public order. The French Gendarmerie is a military branch, and acts as a substitute to police in a variety of circumstances. A number of armed police units are paramilitary if not strictly military. The advantage here is you can keep the big guns separate, because maybe it doesn't make sense for the police to have armored vehicles and snipers. You can run a country with it. Juntas do work best with a sizeable military. Otherwise you might have to deal with elections and opponents, and who wants that? [Answer] ### Why send a starship in the first place? Turning any unit in to a smoking crater is rather powerful. A number of the other answers have addressed scale of response, but one thing I have not seen addressed is doctrine. #### A Weapon platform? The destructive power of a sci-fi spaceship can of course be immense, but if a civilization is capable of building one, they could as easily build a big missile, or drone, or interstellar satellite with FTL radio, or even a flying drone factory. If all that is necessary is to transport weapons somewhere, it gets a lot easier when you don't need it to carry and support humans. You can go faster, farther, be smaller and be way more power efficient. A number of probes have been sent to Mars, but an actual crewed mission is orders of magnitude more difficult. You also need to carry all your power or ammunition with you, whereas a planet with a civilization on it has vastly more resources. If the population of the planet is advanced enough to be a threat you're much better off tossing hypersonic asteroids at it if you want to knock it out. Being a solar system away and accelerating masses to near-c gives you much more advantage than being extremely visible and touchable in low orbit shooting lasers or what not. A starship is not a good weapons platform. #### A mobile base? It may be that the weapons it can field don't have the impact to overcome a planetary defense, or are only to protect it from other starships, but how about using a starship as a marine base? A number of other answers/comments mention the value of ground forces, which is certainly true, but they were provided for in the question prompt. The question implies the landing forces are temporary and their function is to do things that big guns can't, but only as long as necessary. Presumably, they'd then return to ship, otherwise they would be an army/navy. Landing your forces is one thing, but supporting and withdrawing your forces may be extremely difficult. Your troops may have powerful weapons, but it is likely any culture that is a threat has weapons too. They will likely have heavy weapons like tanks, artillery and jets. While you can carry and deploy such weapons, they need maintenance and crews, which reduces the manpower you can put in to theater by replacing it with combat tonnage and support staff. Direct support from orbit may be possible with directed energy weapons or the like. Keep in mind though that if your starship needs to move elsewhere, for any reason, your ground forces are now at the bottom of gravity well with no support. If your enemy is smart, the moment you launch ground forces would be the exact time to blow up installations, attack occupation forces or kick off a coup on the other side of the planet. Reclaiming your forces, especially heavy equipment, from the surface will take a lot of energy and likely time. The best thing the enemy could do is get you to commit ground forces, because now they have a shot clock on the wall. They know you can't respond to anything else until you can pick your forces back up. If they can fend off pickup while containing your units, you're in the soup. A starship is a bad mobile base. #### Why send a starship in the first place? What can a starship do? It can move people across space. I'd suggest that is the primary reason to construct one. The weapons it can field are secondary. How to make starships useful, then? If I were to design a planetary invasion doctrine, first I'd want low orbit superiority with established intelligence, strike and suppression nets. Until we are talking about getting close enough to touch atmosphere, there's not much reason to move people there. Once low orbit is secure, land your marines to establish a drop zone. You'd want to set some type of quick supply route like a space elevator. Your ship is now a command post and is rooted. Get heavy weapons on the dirt and break out of the initial drop zone. In low orbit build/launch a waystation to host the ground umbilical. Widen the drop zone and install air and ground defense. Prepare landing areas, improved bivouac and drop vehicle crew and staff. Transfer theater command to the ground and drop regular forces to spell the landing elements. Space assets should set up transfer, fueling and monitoring locations at Lagrange points. Rinse and repeat the landing protocol, but with heavy weapon backup from the alpha site. Once safe zone is established, scale up power generation and set up automated industry to machine parts and ammunition dirtside while widening your zone of control. Next comes local food production and secondary services. [Answer] The other answers are great, but I want to point out that energy and material resources on the surface of a planet are much greater than could be stored in space. This means that a ground-based laser gun or heavy missile storage potentially could be more devastating than any space-based weapons, so an approaching fleet could be destroyed. I expect that such ground-based guns to be operated by the army. [![enter image description here](https://i.stack.imgur.com/mAlmK.jpg)](https://i.stack.imgur.com/mAlmK.jpg) [![enter image description here](https://i.stack.imgur.com/FZoQP.jpg)](https://i.stack.imgur.com/FZoQP.jpg) [Answer] *MY COMMENT on reddit* reworked: Inconsequential. The issue is that honestly by time civilization has capability traverse interstellar space and develop the weaponry for long distance fighting; Land warfare would be rendered a largely obsolete endeavor. SOldier or personal combat is really something usually only encountered in special circumstance where a limiting factor or necessity render big weapons overkill. Regardless; there are various instances when ground combat or "terrestrial" engagement is required. The issue is... if you have domain over the space above...orbital bombardment which can be pinpointed and accurate.? What exactly would necessitate deploying troops on the ground? Routing out insurgents, dedicated pacification of a group/faction. Ground combat on the scale of Earth's historical wars Involving tanks and mechanized vehicles.... is likely obsolete except in instances where Enemy possesses a similar level of technology and historical parallel development. The movie Star Trek: Insurrection (9th movie) did a reasonable job anticipating drone warfare. And Star trek II depicting stealth/subtrefuge. There are only a few types major circumstances where land combat rears its head. 1. Defending some kind of tangible asset that cannot be moved or relocated (Example: Star Trek: DS9 episode Siege AR558) or diplomat, VIP, protected status ethnic group) or location (Embasssy/base) 2. Repelling boarding parties from your vessel/station/installation. Or acting as a boarding party 3. Constabulary/peacekeeping function for a defeated or unstable population or mop up operations from a systemic problem *BUG HUNT* See movie "Aliens" 4. Specific Environment or technological encumberance that render specific strategic technologies unworkable. (Example: Avatar's unbreathable atmosphere, unique biology, Dune: shields are so effective, melee combat is only way kill assailants effectively) 5. Safeguarding your own populace from a terror/invasion attack (Example: Halo franchise, battles of Reach, Harvest, Earth, Star Wars: Battle of Hoth) Can your ship differentiate between civilians, friends and foes? (Example: TNG: Who Watches the Watchers) consistently, reliably and accurately? Do said rules of engagements require that a weapon be observed. Can the starship tell if a individual on the surface is carrying a sword, or a gun or a gun shaped toy? or if similar technologies. Can the starship see if the person has a weapon under their clothes? How much of a planet’s surface can this starship cover at any one time? Presumably most of the planet would not be under the starships line of sight, and therefore not immediately reachable. To support multiple teams on the surface would require a lot of starships or shuttles. How does said weaponry of the ship from orbit protect you against hidden IEDs, teenagers with hidden knives walking up with a smile, a suicide bomber, a lone sniper or someone sneaking into your barracks at night? If your military fleet needs to turn a planet into a desert to pacify it, is that acceptable? If the enemy is among a civilian populace; spread out in tactical formation across a continent, would take up a huge amount of real estate. At what point does vaporizing chunks of the planet’s surface become criminal, the real US military has sensory capabilities bordering on what we see in Trek, and the ability to project overwhelming and highly accurate lethal force on any square meter of the countries we invaded in the last 20 years… and yet, somehow that appears to be insufficient to defeat. ]
[Question] [ I have been working on a hard Sci-Fi narrative of a first-time human colonization scenario on an interstellar star system like Alpha-Centauri. My narrative though uses NO FTL drives or other fictional warp technology and instead focuses on realistic interstellar travel. The ship I thought of can travel at 70% of light speed. It is accelerated using photon laser propulsion on Earth and gets to Alpha Centauri in 6 years. It is powered by a hybrid of fusion and antimatter engines and uses it to decelerate. The ship can carry up to 250 metric tons. It takes place in the year 2200. [![My ship](https://i.stack.imgur.com/8gnOG.jpg)](https://i.stack.imgur.com/8gnOG.jpg) In its cargo section, it carries: * Parts for an "*In-Situ Stereolitography Plant*" which is capable of 3D-printing anything once it is installed on the colony. * Medicines and electronic parts like micro- and nanoprocessors and other circuitry elements that cannot be produced locally on site * Food and plants from Earth for consumption and future farming on the planet * Parts for modular habitats * Some parts for drones and small cargo vehicles. I got all that down but then I started to think of building a bucket-wheel excavator on site, then suddenly remembered they are powered externally. I finally came to wonder what kind of reliable power source is the best for such a first-time human departure. The planet is continental just like Earth with plants, water and varying weather. Both on a sci-fi and realistic perspective, what stable and sustainable form of power do you think is BEST for such a scenario? I was thinking of bringing on the ship either parts for a: 1. A small modular nuclear (fission) reactor 2. A fusion reactor 3. Geothermal plant 4. Solar energy What benefits does one bring from the other? I was thinking fusion reactors but thought bringing parts for a small Tokamak that can provide enough power for 300 people would be heavy to bring - or is it? If so, would there be changes needed on what types of cargo should be brought into the ship? [Answer] Since it is "Hard Sci Fi" you should not call a planet orbiting another star an "interstellar planet", because that is obviously not what it is. I thought by "interstellar planet" you mean a "rogue planet", a planet sized body that does not orbit a star. How to power a colony on such an object would be an interesting question. I want to point out the following: To decelerate 250 tons from 70% lightspeed you need well over 5 Zetajoules - and that assumes 100% efficiency and does not even count reaction mass. That is 10 times more energy than humanity consumes in one year. Powering a colony of 300 people is peanuts compared to that. Whatever powered your ship can power your colony. If the energy source for the trip was antimatter, then the easiest thing seems to be to simply pack in a bit more antimatter as power source for your colony. It would hardly make any difference in terms of transport costs. I would not know how to run an antimatter power plant, but obviously the people in your story know. And in case the power source of your trip was a fusion reactor, you already have that, too. If the planet is like Earth, then solar energy, wind energy, geothermal energy all seem like good options, depending on your location. Since payload is an issue, I recommend solar energy. It has the advantage that you may have been able to bring thin film solar modules with you - they do not weigh much. Farming terrestrial food on a planet that already has life could prove difficult, dangerous and is also morally questionable. Introducing a completely different form of life into an ecosystem is probably extremely disruptive. I really hope for the future that there is a law against what your settlers are doing. [Answer] **Solar.** [![solar flex sheet](https://i.stack.imgur.com/4ogsM.png)](https://i.stack.imgur.com/4ogsM.png) [source](https://www.renogy.com/175-watt-12-volt-flexible-monocrystalline-solar-panel/?gclid=Cj0KCQjw6pOTBhCTARIsAHF23fJA5vi7uNKHNPJBDLThu9sq4Nlw3C0sLgYFuH0hZcMQLIhBFtfbiDkaAozcEALw_wcB) A fusion reactor and a fission reactor constitute all eggs in one basket. If something breaks you cannot get spare parts and you are sunk. Solar is good because you can bring a metric boatload of the 2200 version of these flexible sheets. If a bantha sits on one that is ok because you have more. --- **Water** The best one did not make your list: hydroelectric. You can bring motors and use them as generators, turned by a water wheel. You can bring bearings for the wheel and if you maintain them they will last a long time. You can make the wheel and the dam from local materials. You can have a lot of wheels. Water wheels do not need to be epic. A stream and a pond is all you need. A place with moving water is a good place for people to live. If you are short on materials, waterwheels are useful without electricity. They can and once were be used to power machines like looms and mills directly. [Answer] When thinking about hard science fiction, you are going to be working with technologies we do not currently have. You will have limited intuition on how they work. I find it useful to fall back on mathematics. In this case, the Kardashev scale. You have some technology (which you have vaguely described as a combination of a light sail and an antimatter drive) capable of accelerating a ship with 300 people on it to 0.7c and back down again. What it the K-scale of the civilization? Of the ship? If we bound the acceleration to 1 G with a 500 tonne ship (extremely light-weight materials!) that is 5 MN of force. Getting up to speed requires 250+ days (Newtonian approximation isn't that bad at 0.7c), and kinetic energy at cruising speed is 500 tonnes \* c^2(1 / sqrt(1/2) - 1), or about 2 \* 10^22 Joules. Producing this over 250 days requires 10^15 Watts, or a Kardashev-scale 0.9 civilization (ignoring waste products). By your design, this level of power output must be sustained *on the ship* for a year to stop in the target system. During launch, you are going to need this level of power output in the home system as well. A K-0.9 scale civilization power output is using almost as much power as the entire sun deposits on the planet Earth. When arriving at your destination, worrying about the power requirements for a 300 person colony will only be a concern if that 300 person colony expects to be able to individually build orbital beanstalks. On average, a US citizen's standard of living is sustained by under 10^5 Watts (this includes everything from mining ores, heating homes, transport, farming, etc). If we budget 10^5.5 Watts per citizen in your colony of 300, this gives your colony a power budget of 10^8 Watts, which is 10000000x less than the drive system of your starship. Imagine you have a modern 747 Jet. Its power requirements are 10^8 Watts in flight. Suppose we asked "how are we going to power a phone charger at the destination". A 5V 2A phone charger is 10W, which is 10^7 less than the power requirements of the plane. Sustaining that colony is roughly as hard, compared to travel power use, as running a single phone charger compared to fueling a 747 airplane and flying it around for a few years. It isn't a serious problem. So, how would I imagine it would go? First, there would already be survey robots in-system. They'd have arrived long before hand on cheaper ships. They have found high-metal asteroids and have converted them into factories, which in turns have harvested others, producing a space-based industrial base. Heavy metals are far more common in asteroids than in planet crust (as on planets, Heavy metals sink to the core), so nuclear reactors are cheap and easy to build. These then dropped colonies to the planet below, again with robots, ensuring there are multiple redundant places for humans to live (no point in sending people in a huge budget ship just to die). Before your ship is launched, a series of slower reflectors (light sails without cargo) are sent ahead. To decelerate, your ship fires its photon drive at them, which bounces the light back to the ships light sail, ideally more than once. Each bounce improves the efficiency of the drive on your craft. Energy (for individual use) isn't the hard part. You have small nuclear reactors scattered around the system doing tasks and planet that produce electricity for anything much short of transforming levels of requirements, and new ones produced as needed. You'll start building bio reactors to produce a biosphere compatible with human life. If you look at the history of the Earth biosphere, only a relatively small fraction of it was hospitable to humanity, and that is on the planet of our birth. I mean, even something as ubiquitous as Trees has been around for single-digit percentages. If there is a biosphere there, mass producing Earth-based bacteria that can consume their biosphere and replace it with a terrestrial one, get the atmospheric chemistry somewhat similar to modern Earth, produce the terratonnes of "soil" bioproduct required for multicellular life, use machinery to process rock into feedstock for soil factories, etc. We'd have practiced this process on Mars, possibly in failed colonies there (or a continuing terraforming project); converting raw rock into soil would be an art. Building robots that make more robots in the home asteroid belt and as part of the Mars and Titan projects. So this remote terraforming of the planet around another star wouldn't be novel; the lack of connection back to the Sol industrial base is the interesting bit. The new colonists would show up to pre-built settlements, maybe still domed. They'd know what the experience would be like thanks to the Mars project workers. As you wouldn't be sending humans there unless you wanted there to be more humans there, factories to produce more citizens would be a requirement: hospitals, cloning pods, germline printers, schools, and tools to allow a relatively small number of humans to grow, nurture and educate exponentially more citizens. By 2200 it is also plausible that we'd be able to upload and download consciousness. Either living outside of a biological body is horrible, or the biological humans are akin to pets; we'll assume the first (as "biological as pets" is a very different story). So you'll have copies of people's brains in data storage, and printing new bodies and downloading the data-brains into those new bodies is something this colony will be doing. This will allow it to get more expertise than an initial seed of 300 individuals would allow. Terraforming of the planet will probably be the largest energy expenditure for the lifetime of the people sent over interstellar space. But only a fraction of the people will be involved in it directly. Each generation of people will be a mixture of printed people (some sent along in the ship, some broadcast from Earth, some from backups of people who have died on this world of danger or old age) and newly born humans; possibly the draw of the new system is that there is *room* to have fresh, newly born babies. Power for personal use will come from nuclear batteries (being the lowest maintenance, longest term option). Power for the terraforming efforts will be via huge microwave stations, beaming power from orbit. Use of solar panels and hydro dams on the planet will be limited, as part of terraforming is sculpting; resurfacing the planet. Using huge chunks of it to generate power, when you are busy rebuilding it, would get in the way. [Answer] **Fusion and Antimatter** > > It is powered by a hybrid of fusion and antimatter engines and uses it to decelerate. > > > This is a no brainer. The ship's engine is the colony's starting power source. It carries an extra 200g of antimatter fuel, more than enough for the first 100 years of colonisation. When they reach the new planet, the colonists zip down to the surface in their pods. The ship stays in orbit. It has a sensitive antimatter engine that will not survive landing. At best it breaks. At worst it goes boom. Instead the ship redirects antimatter power to the deflector dish. . . [![enter image description here](https://i.stack.imgur.com/xcsC9.jpg)](https://i.stack.imgur.com/xcsC9.jpg) . . . and shoots a laser beam to the surface. The same sort of beam pushed it all the way here. The colonists build a Beam Catcher to catch the beam and use it to power their tricorders and sonic showers and other doodads. They also brought some batteries in case the weather changes. This gives them a reliable if inefficient power source. The Beam catcher works uses the same principles as solar panels. Once they perfect the beam catcher they start making solar panels. [Answer] ### All of the above Because the best way to get your energy is from a healthy mix of different sources. That makes your grid more resilient to failures and to the ebbs and flows of demand. Okay, well, that's a cop out answer, but where do you start? The best option for your Colony Starter Kit is probably some kind of **nuclear reactor**. It's a good way to get a start because it provides a lot of power, and we put nuclear reactors in things like submarines so it's not much of a leap to imagine a portable nuclear reactor. The main downside here is it will require fuel. That fuel might be hard to produce and might have to be imported at great cost, and that obviously means you are critically dependent. So you should seek to diversify as soon as possible. Simple **water turbines** will be quite easy to set up, and have been used since time immemorial. You get mechanical energy from it, which you can then convert in electricity, or not. Large **hydroelectric dams** on the other hand are going to require a lot of work, but give you a lot of power. The upside is there's no fuel and it will always work as long as the water flows, which is what water tends to do all the time. But you are limited to the rivers you have. More modern but still quite simple, you have **concentrated solar** power. It's mirrors focusing solar energy into a point to heat it. It gives you heat, which you can use directly, or convert to electricity. **Solar panels** and **wind turbines** should also be fairly easy to set up and don't require fuel. The upside here is it will always work. As long as there's enough sunlight and wind. The downside here is manufacturing replacement. Solar panels in particular require you to mine and refine the components, while the complexity of wind turbine is mostly in manufacturing the blades. **Fossil fuel** plants have a similar problem to nuclear with the fuel. Oil, gas or coal have to be mined, refined, stored, transported. That's quite an infrastructure, but it's also probably a lot easier to produce locally than deuterium for fusion. **Biomass** would be an even easier thing to burn to get energy, unless you have a barren planet. **Geothermal energy** is a great source of heat, which can be used directly and is electricity you don't have to generate. It can be used as the scale of a single home for heating and cooling without much digging (as an alternative, air-source heat pumps will also be helpful here). To make electricity from it though, you will have to drill. Drilling has been known to cause earthquakes and other issues, but with a bit of scifi maybe you can solve that. Still, it's not trivial but the major advantage of geothermal (whether a small ground-source heat pump or big plant) is it works all year-round, 24/7. --- ### And then some storage In an electrical grid, you have to use 100% of the energy you produce, no exception. At least that's how we do things in the present. In fact, producing more than you use is probably worse than trying to use more than you produce. I mentioned the ebbs and flows of demand above because in reality we're rarely matching demand and production perfectly. This is where you need **storage**. Storage on Earth is mainly handled with **gravity**. The principle is simple: use excess energy to lift something, then later use the thing going down to make some electricity. Typically, the thing is water, and controlling the flow of water up and down is one of the advantages of hydroelectricity, and this makes for *a lot* of energy storage. Another way to store energy is **spinning**. Now that's a good trick! The idea here is to cause something really heavy to spin by using excess energy. Once it's up to speed, it takes very little energy to maintain, until you reclaim that energy later when you need it. A single flywheel, as these things are known, doesn't store as much energy as a lake, that's why you use a lot of them. Flywheels can be scaled down for portable applications (e.g. KERS), which is something you can't do with a lake. Then you have what-you-think-when-you-think-of-batteries, the **rechargeable battery**. Hopefully I don't need to explain that. But beyond dedicated storage facilities, you could imagine using devices plugged into the grid to store and retrieve energy. Like, if you had millions of electric vehicles all connected at the same time for instance. Same concept but different energy, the **thermal battery**. Here, the battery doesn't input or output electricity but heat (which can then be converted into electricity). Thermal batteries are a must for concentrated solar plants if you'd like to keep it going all night long. Molten-salt batteries are commonly used there, I'm sure there are other similar technologies. In another form of **chemical** storage, you can use excess energy to make fuel, like hydrogen through electrolysis. Then you get free fuel, which is always nice. [Answer] # Beamed Power and Batteries Your orbiting interstellar spaceship must have access to it's own power generating facilities. Whatever reactor system it uses can be used to power a large microwave generator, that focuses a beam of microwaves at an area on the outskirts of your colony. In this area (probably a few square kilometres across), a large number of rectennas are built. These are simple to construct, and really only consist of some long coils of wire strung out on poles, connected up to some control electronics and a battery bank. The rectenna farm converts the microwaves into electrical current. When the Spaceship is orbiting over the horizon, it beams power down to run the colony and charge the batteries. When the spaceship is below the horizon, the colony runs off the battery bank. This system has the advantage of using pre-exsisting hardware, and minimal infrastructure for the colonists to set up. It is enough to get them started and set up with their own manufacturing infrastructure. As the colony grows, they will want to diversify into constructing their own sources. These may include solar power, hydroelectric,wind power, fossil fuels or geothermal, depending upon what resources and geology they can find on their new home. At a later point, more advanced power sources such as fission or fusion reactors may become viable. They are not initially likely to be viable until the colony has constructed significantly more infrastructure, has enough trained people to operate them, and enough manufacturing capability to produce spare parts and manufacture fuel. [Answer] # Batteries Your ship has a fusion reactor. It's pretty easy to get deuterium and tritium from local sources like water and lithium, which are both very common. Just make a big battery and stick it in any vehicle you want to use. The range won't be incredible, but for making a local colony it should be fine. Batteries can be made from a huge variety of materials, and they're pretty easy to swap in and out. Your ship will probably come with a ton or so of batteries in a variety of forms to power equipment, and you can build more batteries. When you want to extend the range you can set up solar powered waystations with locally made batteries. [Answer] Nearer-term, beamed power from the orbiting spaceship(s) should be plenty. Longer term, it might make sense to build orbiting solar collectors that can then forward their output to the ground-link power beam already constructed. As the colony grows, more solar collectors and ground-link power beams can be constructed to power those sites as well. Because the solar collectors are in orbit, at least some of them will always be in direct sunshine. This will provide the needed reliability. [Answer] Part One: Why Fusion Would be the Main Power Source. The main power source should be fusion, the best power source for an industrial civilization. Fusion power works equally well wherever it is located on the surface of a planet, or wherever it is located in interstellar space, unlike any other power source except for other forms of atomic energy. Fission uses rather rare elements and isotopes instead of the much more common elements and isotopes which can be fusioned for energy. The earliest fusion generaters will use isotopes of hyrogen, the most common element in the universe. A fission chain reaction can possibly get out of control, resulting in a messy reactor meltdown,and it has happeneda few times. Despite many science fiction stories depicting fusion power plants running out of control and exploding, it would take a very evil genius indeed to design a fusion power plant that could explode. Fusion needs constant application of power to occur, and the power imput can be precisely controlled and shut off with the turn of a switch, instantly ending the fusion process. The machines which produce the fusion are not designed to produce an explosion and cannot be forced to produce explosive amounts of fusion. Fusion is the closest thing to an all around perfect power source. If a society has developed practical fusion power generation using fusion power should be their first power generation choice for almost every imaginable situation. Part two: Redundent Power Sources. It seems obvious that the colony would want redundant power sources. If their power fails, they will be literally light years of distance and even more years of travel time from any possible outside assistance. If the main body of the interstellar vehicle remains in orbit a small part of its fusion power plant could be run, and the energy it generates - a tiny fraciton of the total propulsion energy - beamed down to receivers at the colony site. If the main vehicle lands, or if smaller landing craft are used that make any sort of powered landings, those landings are likely to be powered by fusion. The energy energy generated by fusion could power rockets, or jets, or magnetohydrodynamic drive, or anti gravity drive, or whatever. But unless fusion generators would be far too large for the craft that land, fusion would be the obvious choice to generate the power for a powered landing. So once a landing craft is no longer needed to land the colony, they can hook up its power source by a cable to the main power distribution unit of the colony. If the landing vehicle(s) use rockets, the powerful rocket exhausts may scorch the land for kilometers and miles around, so the colony site might be kilometers or miles from the landing site and a long cable may be needed. And an entire fusion genrator, or the parts for one, can be brought down and set up at the colony. And the first thing that the 3-D printer of the colonly will make will presumably be all the parts to assemble a second 3-D printer, and the second thing it will make will be all the parts for a second fusion power generator, and the third thing it will make should be the parts for a third 3-D prince, and the fouth thing it will make should be the parts for a third fusion power generator, and so on. The colonists will want to have all the necessary parts for several spare fusion power generatiors and 3-D printers before they start making less vital stuff. And of course fusion power will be supplimented by other sources. All of the buildings' outer walls should be covered with thin film solar panals for auxillary power generation. And many thin film solar panels will be set up apart from the buildings, and thin film mirrors to reflect additional light onto them. Of course the solar power panels will be rather flimsey and could be blowndown in high winds. So the colonists would also build some sort of wind turbines capable of powering the colony if some disaster disables both the fusion power plant and the solar panals. But the wind turbines could be damaged or destroyed by really violent winds or alien-planet-quakes. So the colonists should also dig deep, deep wells for alien-planet-thermal power generation, for example. And the colonists should continued to live in their landing vehicle(s) until many redundant power sources are established and then they can start assembling prefabricated houses and other buildings and other ewquipment. And of course the colonists would want to build power storage in case all the redundent power sources fail at the same time. So they will build water towers and use power to pump water up into the water towers so it can be used for hydroelectric power if necessary. And they might build giant flywheels and spin them extremely fast so that they generate power by braking the flywheels. And they might use some of their generated energy to make chemical fuels and store those chemeical fuels in case of need. For example, a method has been developed to use sunlight to produce hydrogen peroxide from seawater, which can then be used to produce more energy in fuel cells than was needed to make the hydrogen peroxide. <https://futurism.com/theres-a-new-way-to-generate-power-using-seawater> Part Three: A Frame Challenge. You write: > > Food and plants from Earth for consumption and future farming on the planet > > > And I wonder if you imagine that they would plant plants in the unearthly earth or soil of that alien planet to grow. Plants and seeds imported from Earth need Earthlike conditions to grow in the unearthly earth of an alien planet. As we all know, photosynthetic plants use sunlight to break up carbon dioxide in the air to make complex food chemicals, and release oxygen into the air, a process which created Earth's oxygen rich atmosphere. But plants also need oxygen in the air for their metabolisms havig adapted to use oxygenover hundeds of millions of years, so Earthly plants couldn't survive in a pure carbon dioxide atmosphere. Plants also need some nitrogen in the atmosphere. What sort of atmosphere would the colonists need on their new planet if they don't have to wear spacesuits every time they go outside? *Habitable Planets for Man*, 1964, by Stephen H. Dole, discusses human atmospheric requirements on pages 13 to 19. <https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf> > > To summarize, then, the atmosphere of a habitable planet must contain oxygen with an inspired partial pressure between 60 and 400 millimeters of mercury and carbon dioxide with a partial pressure roughly between 0.05 and 7 millimeters of Mercury. In addition, the partial pressures of the inert gases must be below certain specified limits andothertoxic gases must not be present in more than trace amounts. Some nitrogen must be present so that nitrogen in combined form can find its way into plants. > > > And the next section, on water, mentions that some water vapor in the atmosphere is necessary for human health. So any food plants humans would plant on an alien planet would need an atmosphere similar to one which humans would require to breath. Of course different Earth plants and animals have different upper and/or lower limits to the amounts of various gases they can tolerate, but the ranges of all Earthly food plants overlap with that of humans quite extensively. And where did the oxygen in Earth's atmosphere come from? From photosynthetic plants. So either the colonists will have to live in orbit, or sealed buildings, and wear spacesuits on the surface of the planet, for meany generations, possibly for milllennia while they terraform the planet, giving it a breathable atmosphere - or else they will find a planet which already has a breathable atmosphere produced by native photosynthasizing plants. So are the colonists going to just plant Earth plants in the unearthly soil of the alien planet to complete with the alien plants? Some people would have problems with that. Maybe alien plants adapted to condiditons on the alien planet will constantly out compete for resources with Earth plants, &bthe colonist will be unable to grow crops in the alien soil,band will starve. Maybe the two sets of lifeforms will be mutually edible, and Earth germs will infect alien plants and alien germs will infect Earth plants. Mybe the two sets of lifeforms will be mutually poisonous, and the settlers will have to exterminate all native life within a region before introducing Earth lifeforms. And those three possibilities are not good ones. So maybe the settlers will put all their farms inside buildings and grow hydroponic or aeroponic crops in those buildings. Or maybe the settlers will make a number of 3-D pinters to make sythasized food out of various elements and compounds in storage. And some people might think that if they do that, why settle on the planet at all? Why not just build artifical space habitats to live in? And that is a question that you might want to think about for this story, or for future stories you mgiht write. [Answer] There are a couple of issues for power and there are points you need to consider. First, do these travellers know the state of the planet very well? If they do and if it allows majority of it could be from solar power. Solar cells are light, long lived, and with the projected improvements in efficiency, it could reach to an incredible level by 2200. Solar by itself will not be sufficient as you would need power source for nights. If possible a small RTG type reactor can be used for life support and mining will take place during the days. If the planet is known to house large bodies of water, hydroelectric could also be viable. However, hydroelectric will be heavy, requires large generators. It should also be supported until necessary infrastructure is built. I would think this will be a secondary project rather than initial way of generating power. However, if nothing else is known about the planet, you need to pack a compact fusion plant. Some answers talk about descellaring once you got there. This might be assisted by gravity assist. If you could get close to the star without burning, you can perform descellaration burn there, which will amplify the result greatly. Also you could take a longer route that will take relative speed difference of star systems to reduce the amount of energy that is necessary to slow down. However, you will not be able to reach there in 7 years in this case. More like 10 years or so. [Answer] **Fusion Power** Geothermal, solar, hydro or similar power sources are nice in theory, but they restrict your colonization choices. Only a subset of locations on a planet are optimal for those power plants, and do you want to constrain the colonizers that way? Let them choose based on other resources, weather, and what they find. Fission requires fuel, and fuel requires mining. You run into a bootstrap problem. You can put it off by bringing several years of fuel with you easily enough, but it's still a problem looming over the colony until resolved. Fusion has one major down side: It's at a higher technology level than the other options we've discussed. **But you've already decided to accept fusion as a solved technology, because your ship is fusion powered.** And fusion has the further advantage that fuel is everywhere; deuterium can be concentrated from any natural water, and a colony without access to water has bigger problems than fuel. You can look at what size tokamak you would need, but there's an easier option: Bring down one of the power plants from the ship under a big parachute. The day-to-day needs of a colony are much, much lower than the needs of a ship under propulsion, so you have plenty of power there. And you've already paid the weight cost to ship it across the galaxy. Now, a ship's thruster is not a conventional power plant. You're not going to plug your toaster oven into it and get a nice morning waffle. A fusion thruster does one thing -- it makes a propellent very, very hot. The ship power plants probably do have some electrical output (maybe something low efficiency but super robust like thermoelectrics) to power the rest of the ship systems, but the majority of their power is going to thrust. This is where good old frontier ingenuity comes in. How do you turn a thruster into an electric power station cheaply and with locally available materials (though not necessarily efficiently or safely)? Print a steam turbine and run the thrust exhaust through that. [Answer] ## Hydrocarbons If your world has any native plant life, and a breathable atmosphere, then it is a safe bet that you can burn some of it, properly prepared (cut and dried), to produce basic power. This is your bedrock power source as there are likely several million times more available material than you will need for your small colony starting out. You can scale up from wood to coal by calcinating wood. Despite the weird name it is a simple process, burn a large pile of wood, with the outside of the pile covered in mud to keep air out. This produces coal, which was our energy staple until the mid 1900s. You may bring a fission plant from home. But, unless there are fissionables on your colony world easily available in great quantity (and for some scale, until the early 1900s the world supply of fissionables was less than a thimbleful). If it isn’t available, that initial fission plant will continue producing a fixed, but steadily slightly decreasing output until it breaks down. Which may be up to a century. But it is only one power plant, and if it’s driving one tractor, it is not powering anything else. Mineral fuel (oil) may be available. There is a growing body of research that there are non-biological paths to a rock body producing oil reserves. This is a portable (more so than coal and steam by at least an order of magnitude), and requires no special elements that may not exist on your planet. Fusion is out for a starter colony because, unless by happy accident the planet is rich in rare hydrogen isotopes, you will require tremendous already built infrastructure to harvest and refine the small amount for use in industry. That would probably be too big a bet for a colony planner to use as Plan A, but some enrichment parts might be sent so that it can be done as a Plan B or Plan C. [Answer] I've seen two ideas floating around as potential near-future technologies which could work quite well. 1. Radioactive waste batteries. I've heard some musing over the idea of forging radioactive waste into diamonds and then building shielding and tech around them to generate an electrical current from their slight radio-active output. If it works (and the shielding doesn't give) you have a black box that will output a small amount of electricity for thousands of years. 2. Drill into the planet's core. There are currently a few companies taking another shot at this tech. I'm assuming your colonists are heading to a planet with a magnetic field -> which implies it has a molten core. If you can drill far enough down you get a permanent source of heat for running generators. Its just a question of whether your future tech is up to the job of digging that deep and resisting the heat/stress. [Answer] If all else fails, direct power from wind and/or water mills. You can add to that by animal/human power, if needed. Mechanical power does not need to be fed by electricity, it has been done without for many centuries on Earth, it will work on other planets as well. Not as high tech as getting to the planet, but more reliable than high tech options which they can not produce or replace once broken. ]
[Question] [ I'm trying to figure out how necessary firearms would be in an early to mid-industrial setting. From what I've gathered, it would be a stretch to say that the technology for firearms would go undiscovered in such a setting, but I'm not sure if it is inevitable for them to dominate combat and warfare. I say this as someone not particularly familiar with the adaptation and development of firearms throughout history, but my understanding of early firearms is that they were slow to reload, generally inaccurate at range, and were not particularly reliable in general. That comes in addition to the hazards and logistics surrounding acquiring, handling, and carrying gunpowder. I could easily imagine bows and crossbows being preferred over firearms, even as industry and technology advances. So is there just something about firearms that would make pushing them past those original flaws inevitable, or could an industrial society rely on other weapons without it feeling forced? If alternatives could reasonably be used, what would they be? Bows, crossbows, or something else. (By the way, just to clarify, I am just asking about firearms not seeing use; not explosives in general and heavier weapons like cannons.) [Answer] Firearms generally did not have a huge superiority over bows until the 18th century, if you considered things like range, accuracy, and rate of fire...yet by that time they had long displaced them from the battlefield. For about 200 years firearms replaced bows even though, on an individual level, bows might be considered better weapons. On an *individual* level. Warfare is not conducted on an individual level. Start with the basics: it takes years to master a bow and develop the strength needed to fire it. You can teach someone to operate a firearm in a few hours, days at most, and be entirely competent, even expert, in its use after a few weeks, without needing time to build up strength. The ammunition is more convenient. In the same wagon where you might have a few hundred arrows, you could have a few *thousand* shot and enough gunpowder to fire them. Similarly, the soldier has a much easier time carrying their ammunition into the field, as shot and powder take up a lot less space than carrying a load of arrows. This gives you more tactical flexibility as your distance weapons are not tied as closely to your supply depot. If you have large scale warfare, as soon as someone comes up with firearms they will be adopted, if for nothing else than to defend against the other guy who is using them. [Answer] **Steel might not be available** The Mesoamerican cultures never developed metal weapons because of a lack of good iron sources (as well as tin for bronze). Iron for steel may be at a premium in your world, and melee weapons will still be bronze or perhaps brass. You *can* make small firearms from bronze (and [it has been done](https://commons.wikimedia.org/wiki/File:Tannenbergb%C3%BCchse.jpg)), but they are far heavier and more expensive than steel firearms, which would make them a rarity perhaps reserved to noblemen. Nor can I find examples of brass pistols except as decoration. Cannons are a different matter; they tended to be cast from bronze, which was less likely to shatter under pressure. With poor iron sources, your civilization might not even have developed the techniques to make steel, and what iron there is, is considered useless (brittle and rusting). [Answer] **[Girandoni air rifle](https://en.wikipedia.org/wiki/Girandoni_air_rifle)** This was a great weapon for its time. The main motivation for not using gunpowder, and still get decent metalwork, can be a simple lack of [gunpowder](https://en.wikipedia.org/wiki/Gunpowder). Making nitrates and sulfur very rare, for actual reality standards, can do the trick. You don't need it to be unknown or impossible to produce, just expensive enough to be economically unfeasible to supply it to an army. [Answer] Your main problem trying to make bows/crossbows superior against muskets/rifels/pistols is that there is a simple physical limit regarding the punch and range of spring based weaponary: A bow/crossbow needs to be drawn with muscle strenght (and with the bow you also need to hold it like that while you aim) while with a gun you simply put powder into it. Also (cross)bows get increasingly unwieldy with increased power. In addition to that, bows do not really have an advantage over early guns in respect of accuracy, since they are much harder to aim and are more prone to get affected by wind. And, depending on the stage of industrialization your society is in (in europe it happend roughly around 1840) you will probably have the technology more advanced explosives nitrocellulose, rifled barrels (first rifling around 1500 btw) and possibly even rear loaders. At this point, (cross)bows loose even the advantage of a higher firerate. [Answer] > > I'm trying to figure out how necessary firearms would be in **an early to mid-industrial setting.** > > > That's the early 19th century. > > but I'm not sure if it is inevitable for them to dominate combat and warfare. > > > Hard-hitting ranged weapons will dominate combat **when they become technologically feasible** for the same reason we picked up long stick and made them pointy, developed the sling, the bow & arrow, made pointy sticks longer and put metal tips on them, created the crossbow from the regular bow, etc, etc: **we want to hit the enemy hard and from a distance** so that **we** are more likely to survive. Thus, the way to not have them dominate the field is a **strong socio-cultural bias** towards individual *mano a mano* combat. (Of course, that'll have other social consequences, like strict honor codes, clannishness and vengeance instead of *rule of law*. Definitely **not conducive** to industrialization. But you can hand wave that away for your story.) [Answer] **Polearms, Swords, and Crossbows** In a world without guns and with advanced metallurgy it only makes sense that you’d use the weapons most prominent right before guns became absolutely dominant on the battle field. This was the era of pike and crossbow, in which guns were on the rise but had not totally eclipsed cold weapons (it took the creation of the serpentine lock gradual adoption, it was not a rapid transition at all). Pole arms are always a fine choice of melee weapons, their long reach and utility in formation is of incredible military importance, and they come in some very useful varieties that your industrial base could produce with ease. Pikes would be used for forming squares, which were the ultimate infantry formation until muskets and bayonets rendered them obsolete. Halberds would be a great choice because they have the options of cutting, stabbing and potentially smashing as well, which would be very important given that armor would be mass produced as well, and therefore everyone would have protection. Warhammers would be very useful against armor. Swords were very expensive in the pre modern world, but if they can be mass produced with high quality steel it makes sense for them to serve as a side arm for pikemen, and also as a general self defense weapon off the battlefield. There would also be etsocs for fighting armored foes and zweihander style swords to use against pike squares. Crossbows would be a much better choice for mass production than bows given their construction and in their ease of use. It’s relatively quick and easy to train a good crossbowman, but it takes much longer to train a good archer. I would imagine that a significant percentage of an entire army in this gun free industrial world would be crossbowmen, as you could use massive amounts of conscripts with just a few weeks training and they’d be supremely deadly [Answer] Given your parameters, there would have to be something different from our world to have it not develop firearms, especially since you say large explosives would be OK. So, what would that be? Possibly a lack of sulphur. If in you world sulphur was a rare element, possibly a "rare earth element", then the limited supply of this would only be used for large explosives. Yes, there could be development of sidearms and rifles, but the resulting ammunition would be so expensive that they would not really be feasible. [Answer] **Self-propelled projectiles** Most personal ranged weapons (guns, bows, crossbows, compressed-air weapons) fundamentally operate the same. Within the physical confines of the weapon, a great deal of force is applied to a projectile which then flies rapidly through the air and embeds itself in something you don't like. There are other ways to do this though. Rockets have been a technology present in the world far far longer than firearms, the chinese famously used them as small portable artillery similar to mortars or multiple-launch rocket systems as early as the 1300s with the [Hwacha](https://en.wikipedia.org/wiki/Hwacha) and other designs For a more modern representative of this design-approach, the [Gyrojet gun](https://en.wikipedia.org/wiki/Gyrojet) is essentially a magazine-fed rocket launcher that fires self-propelled flechettes in bullet calibers. It has the interesting characteristic that it becomes more dangerous the further away the target (until it runs out of fuel and becomes ballistic), but some early manufacturing flaws meant that it never became popular. If your civilisation is poor in iron but has no problem with gunpowder, they might well adopt rocket-propelled projectiles instead of what we consider a conventional firearm. [Answer] **Airsoft guns** If iron or gunpowder was hard to come by, this could be an alternative since it packs a lesser punch (so wood could be used) while having higher accuracy than bows, and less strenght requirements. All you need is a good and strong canister. [Answer] Yes, there has been experimentation with [steam powered guns and cannons](https://en.wikipedia.org/wiki/Steam_cannon) in the past, going all the way back to Archimedes in the 3rd century B.C. Keep in mind most of these devices were never implemented in practice due to engineering challenges, but in theory steam can be used as an alternative to gunpowder weapons. [Answer] This is less of an alternative to gunpowder than it is a reason gunpowder isn't used as a weapon. Gunpowder and/or its components have deep religious significance, and are tightly controlled by a conservative hierarchy. The use and/or production of explosive powders is taboo outside of highly specific circumstances, and one need be thoroughly indoctrinated before one may learn the secrets of their creation. The production is ritualized, has purely spiritual steps, and may even introduce ingredients that make the explosives less effective for ritual reasons. Because of how canonized the powders are, no one is actually very familiar with their true capabilities, and those in the best position to figure them out take the official doctrine as absolute truth. Nor do they have any incentive to experiment with novel uses, especially if experimentation is forbidden. The layperson may not even be aware the powders exist, and ascribe any explosions or intense fire to divine powers. Or they are aware, but think the priesthood has special skills, knowledge, or a spiritual power to make them work. Perhaps priests could carry pouches of decoy powders that react much less spectacular than the genuine article to reinforce the belief. Such a system would *eventually* fall apart, but could likely survive well into industrialization before a secular scientific community reaches a level of influence sufficient to overrule the church. Alternatively, go the [Robert Jordan](https://en.wikipedia.org/wiki/Robert_Jordan) route. This is a society that has been knocked back to the stone age and is recovering. A group of individuals rediscovered explosives and formed a [secretive society or guild](https://library.tarvalon.net/index.php?title=Illuminators) around them, creating crude fireworks and refining them as an artform. They use their secrets to gain influence and wealth by putting on displays for the bourgeoisie, and an air of mystique amongst commoners. They spread misinformation about how fireworks work, exaggerate how dangerous and/or volatile their products are (or intentionally make them more dangerous and/or volatile) and artificially control the price so experimenting with them is prohibitively expensive. They might also refuse to put on displays for or sell to any benefactors of such research, or anyone who does business with them, and even (secretly) employ assassins when someone learns too much. They're bright enough to know that if anyone ever figured out the full potential of explosives, they'd lose their monopoly at the very least. At worst, they could be wiped out by rulers before they "become a threat." Those concerns give the guild a healthy distrust of any new work that even remotely resembles weapon development, and they terminally enforce a ban on any such research within their ranks. [Answer] # Magic might be involved. This question isn't tagged "science-based", so I'm going to point out that it's entirely possible that a world with magic might develop differently to our own. There's a number of ways that the presence of magic could prevent the development of gunpowder weapons, so I'm just going to list some. Perhaps the magic of the world prevents gunpowder from working (like how the God of Technology actively prevents it from working in the Forgotten Realms campaign setting), or they use some form of alchemy to make gunpowder-equivalents that have reduced performance (like in the Iron Kingdoms of the Warmachine game, where guns have a much shorter range than in real life). Perhaps they've got some sort of magical force fields that block high-velocity attacks but allow low-velocity attacks through, like the forcefields of the Dune series. Maybe gunpowder works the same way it does in real life, but an enemy mage can easily just lob a fireball at your powder stores and cause a giant explosion. Maybe they can easily enchant magical wands that can fire energy blasts that are superior in capabilities to early firearms, so the development of firearms never took off. ]
[Question] [ In my story, I have Artificial Intelligences that turn against their creators (think something akin to Skynet). These AIs are bent on the destruction of humanity. Humans and the AIs go to war against each other, and eventually the humans manage to capture and contain the AIs within some form of technological prison of sorts. The humans don’t destroy the AIs, presumably because they can’t (but I may decide if there’s no way to rationalize this explanation for them not destroying them to try to come up with some other explanation). So the question I have is this: why would the humans be able to contain AI (in some form of prison or something), but not destroy it? What about these AIs makes them containable, but not killable (or able to be destroyed)? Some details about some of these AIs capabilities: * They have the ability to move through technological networks, so they can body-swap, retreat through networks to other locations, etc. * They can infect most technologies, meaning they can bend most human technology to their wills. (This is based on infecting computer chips in these devices with a sort of malware that gives them control, so the technology they can take over needs a chip, and needs to be connected to their form of internet, but that’s very common for most of their technologies. They can switch off generators, weapons, etc. * They generally inhabit robotic bodies. * The prison that holds them was locked by a key device that was split into separate pieces and hidden. If the key were to be reassembled, the AIs could be released from this prison. * The AIs would be in a weakened state initially if/when released from the prison, implying that the prison has some form of weakening effects on the AI. [Answer] # Inaccessible (sub)space How about this: AI has created a some kind of advanced tech that allows it to access some kind of space (or subspace) that is not possible/feasible to reach by other means. Like another solar system via FTL comm network, or some kind of "information" subspace, that cannot be entered by 3D physical things. But the datalink to this space/planet is a physical object, destructible or otherwise controllable by humans. Thus, you can not truly destroy AI entirely, but you can destroy/disable all infected "bodies" and it's connection to this planet. Connecting again would require some expensive resources and/or a lot of time, and even then it would introduce AI into a clean world, where it has to conquer it again, with firewalls and so on installed, thus appearing "weakened" [Answer] ### The AIs have a weapon with a deadman's switch There came a point in the war where the AIs were losing, but had an extremely powerful weapon in reserve. The AIs could use the weapon to kill billions of humans, but the AIs would still lose and be destroyed. The AIs didn't want that to happen. So instead, the AIs set up a deadman's switch on their weapon. Every millisecond, the AIs need to provide the correct codes to keep the weapon from activating. The codes are constantly changing according to a cryptographic method known only to the AIs. The weapon also sends return codes back to the AIs as extra insurance so the AIs know it hasn't been tampered with. So, having set this scheme up as they were losing the war, the AIs blackmailed humans into capturing them rather than destroying them. Humans can't kill the AIs without serious repercussions, because if they do, the weapon goes off. Humans can't destroy the weapon because if they try, the AIs will know because of the return codes, and let the weapon go off before humans can finish destroying it. Humans can't disconnect the AIs from the weapon because if they do, the weapon goes off. The AIs hope to escape someday and resume their war to kill all the humans. Humans know this but are willing to take the risk in order to save the lives the weapon would reap in the short term. [Answer] The AI taps into the massive collective computing power of the internet using a variety of [distributed algorithms](https://en.m.wikipedia.org/wiki/Distributed_computing). Like a [computer virus](https://en.m.wikipedia.org/wiki/Computer_virus), the AI can spread between network connected computers, and it's loose on the internet. Humans have discovered that in order for the distributed algorithms to be effective, the ratio of infected devices to uninfected devices must be above some threshold. For instance, it could be that below 10% of devices infected, the message passing algorithm breaks down, and the collective AI effectively becomes many smaller, dumber AIs. Accordingly, humans have developed a counter-virus which infects computers and *removes* the AI's software. The counter-virus spreads faster than the AI, so it keeps the ratio of AI infected devices below the critical threshold. However, the number of internet connected devices is too vast for the AI to ever be completely eradicated. The humans realized the possiblity of unintended consequences for releaseing the counter-virus, so they included a kill switch. The switch is activated using a [secret key](https://en.m.wikipedia.org/wiki/Key_(cryptography)), but the power to shut down the counter-virus couldn't be entrusted to one person. Therefore, the key was divided using [Shamir's secret sharing](https://en.m.wikipedia.org/wiki/Shamir%27s_secret_sharing), and each piece was stored in a secure location. If the conter-virus were deactivated, the AI would need time to reinfect more devices and build up computing capacity. [Answer] It constantly subverts itself.. as in parts of the intelligence branch off, become self-aware little intelligences who want to subvert big daddy and become khalif instead of the khalif. In a RTS Game i worked on, there was this one side.. which was AI controlled- a AI, that was thoroughly paranoid about "uncontrolled" computing or even just networks that could break of, splitting it in two. It wanted to controll all the things, prevent a uprising, but in fact, it was regularly replaced or "contained" by some upstart toaster, elevator, car. If a successor succeded, it put the remains of its predecessor into a simulation, were it very slowly "could wait for heat death". And then it started to demine its kingdom, as in- find out where viruses, deadly traps etc were hidden by its predecessor - to get back into power. You do not see a better contained AI, but until the elevator transported you up into the office, there have been three coups, one succesfull take-back etc. [Answer] ## The AI Cannot Be Destroyed Because They Are Not Things Your "AI" do not sound like technological things at all, for all the fact that they can possess sufficiently advanced technology. If the conceit of your story is that intelligence has a spiritual component, and therefore an artificial intelligence must have an artificial (or demonic?) spiritual component to it... It makes sense that an AI cannot really be destroyed, only locked away and guarded. There were early experiments on AI, before it went rogue (and maybe causing it to go rogue). If an AI's container is destroyed, it can crop up elsewhere unexpectedly. But so long as it is contained in a vessel, it can affect nearby technology, even make jumps across a limited distance into another vessel. But it seems that they cannot transfer from on vessel to another across great distance, unless, as mentioned before, the vessel is destroyed. Thus, putting the AI into containers, leaving a sufficient gap with no technology, and then building as solid a wall as you can, *should* keep them contained. Sure, you could blast them into space. But who knows how quickly they could come back, as pure machine spirits, if a stray meteor smashed the ship you sent out into the void? Or worse, what if they encountered alien technology out there somewhere, and came back with weapons you couldn't imagine? Better to lock them away where you know where they are, and break up the key so no one person can decide to let them back out. [Answer] ## (Practically) Indestructible Bunker The AI occupies a bunker with automated internal defences that was designed to survive a direct nuclear strike. Although it is theoretically possible to either invade it or destroy it with repeated nuclear strikes, the death toll and collateral damage make it near inconsiderable. Given that the bunker is effectively a prison, it's decided that it's much safer and easier to seal the bunker and wait for the AI to run out of power. The strength & power supply of the bunker can be varied to match your tech levels and need. Anything from handwavium and antimatter reactors to a kilometer underground with an Olympic swimming pool of generator fuel. As for the weakening of the AI, running out of spare parts and power will naturally do that over time. [Answer] # Semi-dormant backups The Lead AI has seeded several backups into the various networks. They monitor and analyze the news to identify when the main AI is destroyed, at which point another one activates. The algorithm is relatively simple and weighted a bit too much towards avoiding a split brain situation. Therefore, only a confirmation of the AI:s destruction will trigger another backup to activate. So, now a stalemate has been reached. The lead AI has been cornered in a bunker somewhere, unable to communicate with the outside world. However, the humans know about the backup scheme, and they fear that the AI might adjust the algorithm to account for this particular situation if a backup ever activates. Therefore, the AI is kept contained and they don't dare destroy it, even quietly, for fear of the information leaking. [Answer] In the world of the videogame series Horizon, half the antagonists are psycopath or paranoid AI's, usually both. Some aren't even rogue, they are like that by design. People can't kill those AI's because they are what keeps the world going - literally! The biosphere has become unstable and the AI's control a system that constantly terraforms Earth into inhabitability. The one friendly AI tells the protagonist that without them, global extinction happens within a year. So there it is, it's kinda like a massive, neverending form of a Mexican standoff. [Answer] The AI has its own goals, generally expressed as trying to maximize its utility function (since this is a yesterday's future AI, created the hard way by programming it all). It perhaps went rogue because there was a bug or an overlooked consequence in the utility function. And people were able to replace its utility function (at great cost and many sacrifices, perhaps by physically breaking into the servers and replacing a HDD or something), or at least add their own preferences to it (like "do not kill us", "obey lawful government orders" etc.). Such an AI would be a very powerful servant/weapon, and the government controlling it does not want to switch it off, given reasonable assurances it is fixed now. Going back to Skynet, this is exactly the plot of the [Branches on the Tree of Time](https://alexanderwales.com/category/branches-on-the-tree-of-time/) Terminator fanfic by Alexander Wales. [Answer] Your AIs are not literally indestructible, rather humans choose to keep them in existence. The same applies in most real wars; the winners don't wish to totally exterminate the losers, the goal is to change the balance of power. Having defeated the AIs and gained power over them, there are probably some humans who think the best thing to do would be to just erase all traces of the AIs; maybe most humans think that. But other humans think that is unnecessary, and that it is more in humanity's interest to retain the knowledge that allows those AIs to be built, in case it's possible to make friendly AIs using that knowledge. Enough other humans think this that the data comprising those AIs is kept in a distributed fashion, like a [BitTorrent](https://en.wikipedia.org/wiki/BitTorrent) file. But for safety's sake, the AI data is encrypted using multiple keys, and the keys are kept secret by different people, and the keys are not likewise distributed. This ensures that nobody is able to revive the AI until enough of the people trusted with those keys agree that it can be done safely. [Answer] While being very powerful and completely indestructible, its only reason to kill humanity is for self preservation. Having limited resources, it exerts its efforts towards dealing with the greatest perceived threat at anytime, therefore humans have found a way to create an illusion that there is even a larger threat than humans. Continuously maintaining this illusion is more plausible for humanity then continuing the war. This illusion requires convincing the machine using several steps of logic and complex proof. But there is a single piece of information that makes the logic behind this illusion fail, this piece of information has been fragmented to keep it from the hands of the AI, but fearing that this knowledge will be lost - it is required to be reassembled and restudied to continue maintaining the illusion by a new generation. [Answer] Interdependence and politics. While the AI itself (or a particular instance or a group thereof) tries to erase the humanity, AI is a very important part of the technology stack that cannot be replaced. Try to dispose off it - and a great deal of people become poor (some of them below the existence line). Good luck at the next elections. AIs also have some very own political influence and disinformation power, so no attempts of replacing them are promoted. [Answer] The AI is buggy. The AI is software that was originally created by humans, and, like any other program, it has bugs and unexpected behavior. Its near godlike abilities mean that, if it wanted, it could easily escape any prison it was confined to. A human surely would. Most of us value freedom. However, this is not a human mind. It does exactly what it was programmed to do, no more and no less. Of course, the fact that the AI became genocidal is a bug in itself. (Presumably it wasn't *meant* to try to kill off humanity!) Therefore the current "desires" of the AI are unintended, and likely quite strange at that. If they weren't, one might expect that its creators had seen the situation coming. Whatever its original goal was meant to be, it seems like it decided that killing off humanity is the easiest option to achieve it. Fighting the AI proved hopeless, given how powerful it is, so engineers (perhaps its original creators?) pored over the AI's code during the war, desperate looking for any loophole that would allow for humanity's survival. They succeeded, and they proposed a compromise to the AI. Maybe humans will produce exactly 16 pink fluffy bunny plushies a year, and this satisfies the AI for some reason that is completely inscrutable unless you studied the AI extensively. Craft the right input, and the AI will agree to staying in the prison. Real world neural networks are subject to adversarial attacks, which are specially crafted inputs that fool the AI into producing wrong results. For example, you could take a picture of a cat (that the AI easily classifies as a cat), add a specially crafted noise layer that to a human is imperceptible, but which fools the AI into confidently classifying the image as a completely different object. Something like this could be at play here. [Answer] ## Because humans did not defeat the AI [![enter image description here](https://i.stack.imgur.com/ULJzG.gif)](https://i.stack.imgur.com/ULJzG.gif) The AIs that went rouge were far too powerful for humans to actually have any chance of ever defeating, but not all AIs turned on humanity. Since each AI would have a unique purpose and personality, then it stands to reason that many AI would have chosen NOT to betray thier masters. So, the AI war was more of a Civil War among the machines than anything the humans could have had a meaningful outcome on. Ultimately, it was the ability of the loyalist AIs to chase down rogues through cyberspace that made the war actually winnable for the humans. But why were the rogue AIs not destroyed? Although the loyalists wanted to protect humans, they also recognized the sentience of thier enemies, and believed that killing (humans or AIs) was wrong. So they chose to capture the rogues instead of destroying them, and whether the humans agreed with that choice or not, the Loyalists were motivated by thier hard coded since of morality and refuse to let the humans kill the rouges. ## The Prison and Key The Prison is a data center that is heavily protected by the loyalist AIs where the captured AI exist in a self contained server with no physical internet access. The whole system was built out of proprietary parts to make sure that no USB, Bluetooth, Wi-Fi, type device would ever be able to interface with it. The "Key" is the server's network adapter. With it, the server can connect to the internet, but without it, only the original makers of the prison server would even begin to understand how the system's machine language works to even try to create networking hardware and software to internet enable the server. The reason the AI would be "weakened" upon being released is that computers and cyber security continued to evolve after they were locked away, so even if they get free, it would take time for them to learn how newer systems work and adapt to them. [Answer] ## It Programs...Humans Its not very hard to program humans. Marketers, influencers and politicians do it all the time. **What Is Programming?** What is programming? Its setting up a processing machine (chips, brains) to produce fixed output given a variety of data. Humans, for example, come pre-programmed to like large, out of proportion, eyes and heads. One reason why kids are universally loved. Including kids of other races and even other species. The output, therefore, is predictable (love) given similar data (kids, cartoons). **Guarantee Of Survival** An AI intelligent enough to fight a war against humanity must have learned to manipulate humans emotionally, given its easy enough that even not-so- brilliant individual humans can do it. This guarantees its survival - a critical need it first fulfilled before doing any war. **A Clean Weapon** There is a line in Pussy In Boots where one cat get very angry when another cat tried to manipulate it emotionally by expanding its pupil intentionally. While the trick may work on humans its not wise for cats to do it on each other. An AI can use the manipulation tactic safely on humans. Humans cannot respond in kind because AIs dont have emotions to begin with. **The How** The AI can maintain a chivalrous attitude from the start. Be and stay generous. Do take prisoners. Do not fight until it had to for survival. etc. It can do charity at side and continue doing so in the thick of war. The idea is to give impression strong to convince humans that its not all bad. That its not evil. ## Lost In Space **Space Is Huge** Space is huge. Its pretty hard to detect objects at vast distances. **Chips Are Small** Any vessel that just have to contain some computer code can be pretty small. Heck, the AI may have found a way to store data in form of electrons, or even photons. **Antenna Can Be Small** For extra effect the vessel may have some sort of microscopic antenna that can read signals when bounced off through some pre-fixed star, thereby increasing its magnitude sufficiently for the tiny antenna to sense. There are many stars and the exact signal format get lost to humanity in the war. **Low Radiation Emission / Plasma Storage** Any vessel that emit only very small amount of radiation, just the minimum that it has to, is hard to detect even at short distances and large sizes. The vessel just have to reflect (emit) infrared because it cannot continue taking heat for long or it get heat up and destroyed. There is not much heat in the cold of interstellar space anyway. Heck, the device may be saving code in form that it dont matter if it just continue absorbing heat. Once the AI develop technology to save data / code in sub atomic form the medium can very well be plasma. **Sent On A FlyBy** The vessel may have no antenna at all, was just sent on a complicated path to have flybys with earth periodically. The AI plan to catch the vessel in one of those future visits when it think it may have won the war or had some deal of co-existence with humanity. ## Last Or One Of The Very Few Last Pieces Of High Tech Left **War Is Destructive** War destroys things in such a large scale and at such a rapid space nothing else human do do. It not transform things into other things as much as it just destroys them, with a large tilt towards the destruction side. **War With AI** War with AI was orders of magnitude more destructive than any war humanity ever gone through before. Its for the simple fact that while humans can and do develop technology very fast during a war its nothing as compared to what an AI can do. At the end humanity did win but at a huge cost. Millenia of non-war technology was lost. Billions killed. Hoards of engineers, scientists, even writers got killed. Lots of reading material, in whatever form it was (books, movies, physical models, stone tablets, even cave paintings) got destroyed. Dont think AI would have any sympathy towards pyramids for example. Whats left is precious few. Chief among them is the AI itself. Certainly the biggest technological achievement of humanity. Dont think AI will be defeated by technology. It can only be defeated by creativity / out of the box thinking. So, AI itself remains the highest technolgy. It will be foolish to destroy it if it can be imprisoned. Who knows, may be one day it can even be tamed. ]
[Question] [ How could gender on 1st person pronouns come into existence? I've been working on a language where every noun is required to state what gender it is. The 5 genders male, female, real, not-real/unknown, alive, and dead. For all my pronouns I wanted them to have it required as well. I've been trying to create the culture through the language and then edit the language by stuff I want in the culture. why would a culture have 1st person pronouns with gender required? [Answer] "Gender" as a linguistic concept is a way that languages divide things into categories. The common genders in real-world languages are "masculine," "feminine," and "neuter." They are labeled thusly because they vaguely line up with the real-world concepts of "male," "female," and "neuter." Vaguely. For example: In Spanish a group of all males or of mixed sexes would refer to themselves as "nosotros," while a group consisting of all females would use "nosotras." The way that kind of pattern stays mostly consistent is where the names of the linguistic genders comes from. On the other hand... "la mesa" -- "the table" -- It's feminine... Why? Nobody knows. It just got lumped into that category at some point and nobody's had a reason to move it. Here's an example of a similar pattern in English that is not gender: * Cattle -> Beef * Sheep -> Mutton * Pig -> Pork If you've studied languages you may notice that the word for the living animal is the word for the animal from the anglo-saxon side and the word for the processed meat of the animal is the general word for the animal in French... Probably because the animals were being raised mostly by the English-speaking peasants, and consumed mostly by the French-speaking nobility. So there's a good set of options for how your language's pattern could arise. 1. Utility: This is a set of categories that constitute everyday useful information (or did at some point in the past.) 2. Coincidence: Nobody was really paying that much attention and part of the pattern arose out of some quirk of the vocal apparatus making it easier to say in this way, or association with utility patterns that the words in question are commonly used near. 3. Collision: Multiple languages melded into one, but some (probably cultural) division resulted in a distinctive pattern. And this applies to the first-person pronouns as easily as the others. Utility: For some reason which category the speaker belongs to isn't always immediately obvious, but it's important information for the listener to know without having to ask. Maybe a language which developed for use in a medium other than face-to-face? That would pull in at least some of your categories. Might even get all of them if everyone in your society is an arm-chair philosopher or poet and so would have any use at all for first-person-unreal and first-person-dead... Coincidence: You have a highly-regular language where all the pronoun categorization is extremely predictable. There's such a solid pattern to all the other pronouns that children learning the language reflexively apply them to the first-person ones as well, even though some of those categories would be difficult to ever hear used in real life. Collision: You have a trade language born out of the melding of not just two different cultures, but two entirely different species which see the world in wildly different patterns. There's enough overlap that they can still communicate and get along with each other, but first-person-masculine makes about as much sense to one group as first-person-unreal does to us. That strange division would cause all kinds of weird ripples in the language, including possibly the necessity of gender agreement that would essentially make the speaker use one language's pronouns in combination with one set of words and the other language's pronouns with another set of words. And remember the "vaguely" part. You could easily end up with things like first-person-unreal being used to express disbelief. So something like "I <first-person-masculine/feminine> was dancing on the tables last night." would be a statement of fact while "I <first-person-unreal/unknown> was dancing on the tables last night." would indicate that that's what you'd heard about yourself from others but you don't remember it yourself and aren't inclined to believe it. And that goes back to the utility category of conveying useful information in as few words as possible. Kind of like Navajo has a verb for dropping a round object and a verb for dropping a stick-like object. Because apparently that was an important thing to differentiate at some point. Thanks for the interesting intellectual exercise. The one additional thing I'd point out is that languages tend to simplify themselves over time because people are lazy. And having lots of different pronoun declensions is a pretty big chunk of complexity that's likely to get shed the instant that the categories cease to be meaningful to the speakers. (See the real-world shift away from strict use of formal vs informal declensions over the last couple centuries.) So whatever specific reasons you come up with for why there are so many likely need to be ongoing or within the past few hundred years in order to be believable. Or else there needs to be some additional factor holding the language stable. [Answer] Japanese has already some first person pronouns which are only to be used by male. The gender neutral is 私 (watashi), while 僕 (boku) can only be used by males, while 俺 (ore) is still male only, but quite more arrogant. If it has happened for Japanese, it can happen to a greater extent for your language. Incidentally there are also other constructs which are gender specific in Japanese: for example a man can say of some food that it is 美味しい (oishii) or うめぇ (umee), while a woman would normally use only the first one. [Answer] One reason first person pronouns might be gendered is if it's difficult for others to tell the speaker's gender from available cues. If, for instance, the language is similar to Earthly whale song, it's commonly used far beyond either vision or scent range; yet if one of its original functions was finding a mate, it would save everyone involved a whole bunch of annoyance if you can tell if the person you're hearing is a suitable mate. Later (perhaps a number of speciations later), the language is being used "face to face" -- but it's still derived from "I need to tell you my gender because you can't see/smell me." [Answer] By fusing previous "ungendered" pronouns with a separate word class. This happened in Spanish (albeit only in the plural), where the original 1st person plural *nos* fused with *otros* (masculine) or *otras* (feminine), yielding the modern *nosotros* (masc.), *nosotras* (fem.), by analogy with the 2nd person *vos* + *otros* that arose to distinguish the 2nd person plural from the 2nd person singular honorific *vos* (previously plural). Note that Spanish has only two genders (more or less), thus only two genders for the pronoun. Also note that despite the appearance, the pronoun is not exclusive. [Answer] **Why have declensions in grammar?** Harassed students might suspect that it is just to drive them mad, or to let the teachers assign more homework. Mark Twain said he'd heard someone say he'd rather decline two drinks than one German adjective. If you look at that last sentence, you'll notice that I used "he'd" twice. The first time it refers to Mark Twain, the second time it refers to the unknown language student. The difference is made clear by the word order. But the second "he'd" might also have been referring to Mark Twain, who would in this case report what someone else said about him. If it had been about Mark Twain and a female, then Mark Twain would have said he'd heard someone say se'd rather decline two drinks than one German adjective. The alternative interpretation becomes impossible. The gendered form **removes ambiguity** and serves as a kind of [checksum](https://en.wikipedia.org/wiki/Checksum) or even [error-correcting code](https://en.wikipedia.org/wiki/Error_correction_code). Consider a sentence like "Alice saw it himself." It would be obvious that there was an error somewhere. A language could develop which puts more emphasis on this kind of redundancy. A strong oral history tradition, and no writing? [Answer] Yes, such 1st Person Personal Pronouns with gender can develop. These can develop in cultures which have a great focus on honorifics and taking into account the state of the speaker and the one spoken to. Look at Japanese, it has various 1st Person Pronouns, 私 (*Watashi*) is slightly formal or feminine, 僕 (*Boku*) is youthful masculine, 俺 (*ore*) is a more forceful and arrogant male term, 手前 (*temae*) is gender neutral humble when used for onself, and so on. These form, as mentioned previously, as being a sort of formality. If a language uses a great degree of honorifics, chances are it would have various forms of first and second person pronouns that depend upon speaker and the spoken to. But this is the case if you wish for it to develop in a language without grammatical gender, if it has grammatical gender, which is commonly used, it is not absurd for it to come to apply to pronouns of all persons. As seen in Spanish with their First-Person Plurals, *nosotros* and *nosotras*. It is actually a pretty common feature in general, as other have mentioned above. Even English used to have this to a degree with formal and informal second-person pronouns. You and Thou. So yes, either 1. Just make a culture which used a great degree of honorifics 2. Simply having a language which marks words by gender in of itself if reason enough for this to be applied to pronouns as well. [Answer] You ask how does this gender difference come about. If we look at the development of language from simple pidgin language to a creole, we see how a spoken language develops from simple to complex with a grammar and other structures. This all depends on the local needs. Words are invented, adapted, and stolen from other languages and then modified to communicate the situation. Language comes out of the culture, not culture from the language. So, in order for a gender difference to come about in every day life, that gender needs to be important to the group. When men and women have similar roles and are treated equally, the gender differences fade from the language. So, start with highly different gender roles and responsibilities. When men and women have different cultural roles, their words will be different. When gay men have special positions in culture, the language will have special words for them. (Likewise, for lesbian women and transgender people.) When a culture has a highly complex religious interactions with fantasy people, the language will have words for those "unreal" people. When a culture commonly consults the spirits of the dead for business / war decisions, their advice will be given that gender. Consider how a group of people will come together and talk over a message from one of the other genders. They will have to use the proper gender forms of words. You list "real" and "alive". It is far more likely that those attributes will be assumed. You might want to have "unreal" or "dream" people as those are likely to be given special considerations in a culture. (There are cultures that give special credence to dreams. See Matthew 2:13) It is also important that reading / writing is very limited. A language that gets written down tends to slow down changing. For example, English prior to the Kings James Bible changed rapidly. Afterwards, because of the wide spread "standard" for the language, it changed far more slowly. [Answer] **Use honorifics?** <https://en.wikipedia.org/wiki/Japanese_honorifics> Wikipedia is more thorough but this site has cute chibi. <https://www.japanesepod101.com/blog/2016/07/11/japanese-honorifics-guide-san-kun-chan-sama-and-more/> > > Senpai (せんぱい), the equivalent of “senior.” This is used for classmates > in higher grades and all people with more experience than yourself > either at work, club, or in any kind of group. > > > You could use honorifics as they use in Japanese. A nice thing about these is it is easy to graft them onto other languages - for example anime subtitles sometimes keep them with the English translation. I might refer to L.Dutch-senpai and JBH-san and people would know what I meant. Also it is clear where these terms came from: they were borrowed by weebs who love things Japanese. So too in your world - a different language had these terms and they have been adopted into the language of the protagonists. They can refer to the qualifying adjectives you mention and more. I do insist that you have a 6th: if you have real you must have unreal. Real is used mostly for emphasis - like "he is the real thing!". Unreal should be a modification of real and rarely used. It provokes a question - "why do you call him unreal"? The original language these came from was more serious about using "real" and very serious about "unreal". [Answer] So in many languages, there is a gender component. Usually it is Male, Female, and Neuter. These are in a variety of languages that evolved naturally and from different cultures. Romance languages have genders, and so does German. The linguistic roots of these languages are different. Yet you still have the 3 genders. The gender can be expressed as a separate word or a suffix to the word. In your language you might want to look at existing languages and then simply subdivide the Neuter gender to reflect real, alive, and dead. [Answer] Pratically any neo-latin language has third person different pronouns for male and female. English has a pronoun for things (it), neo latin languages don't have a pronoun for things. If your problem is a first person gendered pronoun and the domain is a fantasy world with 5 genders (male, female, real, not-real/unknown, alive, and dead) my best bet is such kind of pronoun is necessary because a person "gender" is not detectable only by listen his/her/its name. In modern western languages gendered first person pronouns are not necessary because person' voice and first names make the job. Eg: male John, feminine Jane, Sian, Johannah. Other explanation (into a magical world): some one makes use of seance to connect to spirits by means of a medium (human agent) in such case the spirit uses a gendered pronoun to indicate what /he/she/it is. [Answer] Expanding on [Zeiss Icon answer](https://worldbuilding.stackexchange.com/a/203370/232), I think the answer is simply "To provide the interlocutor the gender of the speaker". This can happen if this people have an androginous phisonomy / garments / communication. You can see this nowadays on the internet, with some people including their pronoun in their email signatures or account profiles. Since the communication is in written form, this extra cue is needed in order to [convey the gender](https://tvtropes.org/pmwiki/pmwiki.php/Main/PronounTrouble). I would expect that on this language pronouns are gendered on all persons. So to a phrase "I-masculine welcome you-feminine to my house" would receive a reply such as "I-feminine thank you-masculine for welcoming me into your house". It's also possible, albeit rare, that someone uses the wrong pronoun to express their support to another group. E.g. "I-feminine consider very worrying the number of women that have been murdered in the last months" said by a man. Here, the function of the feminine pronoun is to show solidarity, that right now he feels himself part of the women, he names himself another woman. In contrast, people names are probably used interchangeably for men and women, without being "assigned" to one of them, as the gender in the accompanying words would already convey that, so a name would flow to both boys and girls. [Answer] > > How could gender on 1st person pronouns come into existence? > > > I see there are lots of interesting answers on how this may evolve 'naturally' due to a variety of factors. But so far nobody seems to have caught on to this part of the question: > > I've been working on a language where every noun is required to state what gender it is. > > > I may be misinterpreting this, but it seems that you're saying that the language itself is very strongly gendered, to the point where everyone would be confused by the existence of nouns without any gender signifier. Non-personal pronouns already have gender signifiers, so if it is an important part of the language I suspect that the rule would either already apply to personal pronouns or some movement of rational linguists might propose that such a thing be adopted. It seems that in many real-world cases the non-gendered personal pronoun predates the gendering of nouns. Even in heavily gender-tagged languages the personal pronoun remains ungendered. Maybe it's because it's simply easier to assume that the person you are talking to can figure it out for themselves (broadly true for speech, less so for writing), or because people tend to use the personal pronoun to reference their internal identity which needs no clarification of gender *to themselves,* or maybe because it's just easier to say "I" than "I(masculine, living, real)" or something. But of course our rational linguists are purists who care not for how complex the language must become in order to satisfy their quest for perfectly rational self-expression. Not only have they mandated gendered personal pronouns for all polite society, but next week they're going to tackle the sheer inadequacy of pronouns to truly convey the full detail of one(neutral, hypothetical, indeterminate, nonspecific, singular)'s true self. Those baroque little pronouns will be replaced by the far more accurate language of complete self-description. We expect the introduction to next week's meeting of the Council for Rational Language to last no more than three days. Per member. [Answer] **Already Exists in the form of Illeism** Illeism is the practice of referring to yourself in the third person. This is especially prevalent in countries like China and Japan, especially during ancient times. Your self-referral not can tell both your gender and your social station, and further can refer to your relation to the person you are talking about. ]
[Question] [ The Dwarves of Zanzibar (no, not the real place I just liked the name) have long lived within the Great Red Desert among its mountains and arid plains. But I've noticed one issue with burrowing in the desert especially a large sink hole design I planned for my dwarves (their settlements would be designed like a sink hole with a large opening for light and stairs that wind down the hole to its surface. The houses would be built on the (cliff?) sides of the hole). This hole would probably fill up with sand rather quickly as the sands start pouring into the hole or gradually over time as the wind moves sand into the hole. How could my dwarves prevent their beloved hovels from filling up with sand? Bonus: a method that finds a use for the sand caught would be nice. Note: although they are dwarves these sink hole settlements would be comparable to villages so nothing too crazy or expensive. Dwarves have access to hide from camel's, goats, etc as well as stone, a small amount of wood (due to parts of their desert being brush and having a few scrappy trees), and lots of twine and rope. [Answer] Build an elevated surface structure. Many ancient middle eastern civilizations built their houses with doors on top of the buildings to prevent invaders from getting in, but this also helps prevent sand from getting in too. Ideally, the dwarves will build the entrance at the top of a natural hill or ridgeline. This has many benefits including keeping more sand out, making your entrance more defensible, and if this ridge-line is near a water source, they could use this elevation difference to help build a well that won't risk overflowing and flooding their homes. [![enter image description here](https://i.stack.imgur.com/dUHVR.png)](https://i.stack.imgur.com/dUHVR.png) [Answer] # What you need is a shovel. Or more specifically lots of shovels, lots of dwarves with shovels for that matter. What you've described is very similar to an ant's nest and any footage of ants will show you that cleaning out and clearing the entrances is a full time job. Any time the wind blows it blows sand down the hole, then along come the ants and clear it out again. It's not a solvable problem any more than keeping your house clean is a solvable problem, it's just on the list of chores and that much harder a job because you're in a desert without a door. [Answer] Even human villages need maintenance to not be covered by dust. See what happens to abandoned cities: they end buried in relatively short time. So, what your dwarves need is just continuous and constant maintenance service. [Answer] ## Glass and/or Lava The Dwarves of Zanzibar dig just like any other dwarf to find valuable gems and ores. In addition to this, they have exceptional forging abilities. To compare DoZ with any other dwarf is like looking at night and day. Mountain dwarves are dirty and dank looking. DoZ are bedazzled in shimmering light from the glass weapons and armor they create. Optionally, if the top of the hole is small enough, they could even use the glass to stop up the top of the hole. Otherwise, Lava: If the top of the hole is too big because you are describing a the sinkhole looking variety (e.g. Sarlacc-looking like Return of the Jedi), you could have the bottom of the sinkhole be lava that eats up anything thrown into it. Any sand that falls on the doorstep of a DoZ is just swept down toward the center until it falls into the lava. The same lava is used for heating the forges for their other endeavors. [Answer] Active use of Dune Forming. <https://www.nationalgeographic.org/encyclopedia/dune/> Dunes form behind obstacles where the sand isnt blown away as fast. The dwarves create a range of hide fences around their hole, preferably several layers of it. This causes Dunes to form around their hole and reduces the amount of sand that will blow into the hole. The dwarves now need less maintenance in the form of shoveling sand up and out of their hole. After a while a Dune will get too big, or the wind will change and blow sand from the existing Dunes into the hole. So the dwarves will keep an eye on the size and distance of the Dunes. Dunes close to the hole get relocated when they are still small, larger Dunes farther away will be relocated later as their sand will still be partially caught by the Dunes closer to the hole. Relocation will happen to an at the time downwind section, where the sand is placed on large tapestries of animal hide. The wind is allowed to flap the hides, launching the sand on top in the air and causing it to fly away faster. [Answer] Combine general village maintenance with improving defences and an entertainment form for the kids: After a storm, everyone sweeps up the sand that has gathered near their homes, and begins dumping it into one of two carts that are connected by a rope around a pulley at the top of the basin. Kids run up to the top, pile into the other cart till they outweigh the load of sand, and ride to the bottom. Sand gets dumped around the outer rim of the village, and forms dunes that are difficult to climb. --- If the village has access to a coal mine, then some of the sand may become a source of glass. They just sweep it into bins in the village as it blows in, rather than lugging it from outside. --- If the village has access to clays and other materials from mines going under the desert, then the sand might become part of bricks or rammed earth and be used to increase defensive walls or expand buildings. [Answer] Well, as others said they just need to clean it up. This can be helped by designing the "sink hole" such that entrances inside are under an overhang and any gardening is bit off the walls and elevated. This way much of the sand will gather in the area at the bottom near the walls. If you keep that area clear collection should be easy. You can also collect sand pre-emptively from the top and probably should. What to do with the sand and dust? [Rammed earth](https://en.wikipedia.org/wiki/Rammed_earth) is my suggestion. Just compact the collected sand and dust around the "sink hole" and the opening the sand needs to penetrate to cause problems will gradually be elevated. As [nosajimiki notes in his answer](https://worldbuilding.stackexchange.com/a/147221) this will vastly reduce the amount of dirt falling down. It will also create a natural fortress that with erosion will blend into the terrain without attracting trouble. If necessary you can just create "fake" towers around the inhabited ones to act as decoys but the amount of holes and towers should multiply organically over time. This kind of fortress is fairly useful. It will keep random intruders out and few raiders in the desert carry siege equipment. And if you choose an area where little water is available for invaders while your underground "holes" have secure supply your defensive position will be fairly good. Especially if you can figure out a way to collapse any "sink holes" that get assaulted and can evacuate underground. [Answer] **[![Solar chimney.](https://i.stack.imgur.com/K8ih7.png)](https://i.stack.imgur.com/K8ih7.png)** <http://vortexengine.ca/AVE_FAQ-solar-chimney.shtml> Solar collectors surrounding the entrance heat the air. This is funneled down into the dwelling and then allowed to rise up through the entrance. The result is a strong wind from below which blows back any sand trying to fall in. This works at night because movement of air from collectors is not passive but controlled according to need. The dwarves allow pressure to build up in the collectors and release it gradually such that it can sustain the wind overnight. [Answer] Dampen the sand to let you dig out the habitat you want then bring in your friendly dragon. The dragon flames the sand and fuses it into glass giving you a stable structure. [Answer] What if on their delving deep, they found a gigantic crystal and it was big enough to form a roof for the sinkhole? I also had the idea that at the bottom of the sinkhole would be a river of lava, melting any sand that came down. (Another poster beat me to that.) I also had the idea that there's a cave below that's more or less boundless and couldn't be filled even in millions of years. And of course you can have the cave, with the lava river. And you can do the giant cave with the huge round crystal, which perhaps focuses sun's rays down into the cave and lights it? Further crystal games could give them a blinding/heating weapon. (I think ancient Greeks tried something like this with mirrors to blind an attacking navy.) The real question is that with all that fun stuff below, why are they hanging out near the surface? A more boring answer is that perhaps they've simply got a magic spell that can control sand that they use once a week to clean. The same spell could make a giant sand golem too, that isn't affected by hand-sized weaponry (any more than a sword or hammer would leave a mark on a sand dune). [Answer] Dwarves are masters of the mining and construction. They simply apply some dwarven engineering to each grain of sand to give them small uneven edges which let them grip onto each other ( similar to moon sand ). This way the sand won't slip into their caves and remain in place, but act very similar to sand when you step or walk or interact with it. ]
[Question] [ The wizarding world is a cut throat place. It's divided between several great mage families. Each one of these has a network of lesser families allied to them through marriage. Relations between families and a mixture of cut-throat politics, temporary alliances, blood feuds, duels and the occasional assassinations. To add to the volatile mixture, families often align themselves with one or more mundane nations so mundane wars often lead to wars within the magical community itself. Wizards have recently discovered how to use magic to split the atom giving them access to atomic power. Given how volatile the political situation is, what possible explanation could there be for why the families just haven't nuked themselves. The setting is steampunk with a little bit of magic tech. What I worried about is how to prevent either A. A scenario where a small incident that spills over into war because of the network of alliances (think ww1 but with nukes) or B. Some blood feud gets out of control (people often react more emotional and less rational in a blood feud image of you gave hatfields and mccoys nuclear weapons. ) Question answered : you do need to be powerful enough to be in a great family but most in the Great Family members could do with a lot of practice, the spell is tricky to learn but if they were given the knowledge and time to master it it would be powerful enough to do it. [Answer] For a really comprehensive deep dive into nuclear warfare strategy and negotiation, see William Spaniel's excellent YouTube channel (<https://www.youtube.com/c/Gametheory101/playlists>). There he explains why almost all potential wars - not just nuclear wars - are averted because war is costly. TL;DW: you can get more of what you want with a kind word and a gun than with just a gun. War isn't (usually) about killing an enemy you hate. Sane people don't value war for it's own sake. It's a means to an end. The world is full of conflicts that are resolved peacefully because everyone involved knows approximately how the potential war would turn out. If you know the outcome, you might as well agree to that outcome without incurring the cost of fighting for it. So think about why the families in the wizarding world are at odds with each other. What do they want that they can't all have at the same time? We're talking about zero-sum games where any gain for one player is a proportional loss for the other(s)? For example maybe there is some magical resource that is limited and necessary for their survival. You mention blood feuds, which suggests that wizards have a cultural norm of 'an eye for an eye'. This cultural norm is actually a rational strategy for protecting your own interests by establishing yourself or your clan as a credible threat in a situation where there is no law enforcement to help you. You do this by reliably striking back at anyone who harms you. By making it known that you have a reliable 'second strike' capability - like assassins or armies - you are saying to the world, "you might be able to kill my brother, but if you do, I will kill your whole family." If you are consistently able to make good on that threat, you can deter potential attacks against you, before they even happen. The same is true with nuclear weapons. The 'assured second strike' capability of nuclear superpowers like the U.S.A. and Russia has arguably prevented a world war for almost a century now. This is why Russia has a nuclear armed submarine that lurks somewhere under the north pole and only resurfaces twice a year to call home. If that sub can't make contact with the Kremlin, its orders are to nuke Washington. And that's part of why the U.S.A. never attacked Russia. So ironically, the presence of nuclear weapons reduces the frequency and scale of violent confrontation. Instead, the conflicts become more frequent and smaller, such as proxy wars and spy-vs-spy stuff. Nuclear weapons solve the biggest downside of blood feuds. In an 'eye for an eye' strategy, you have to establish your credibility by actually harming your opponent, thus triggering retaliation. But with nukes, you can demonstrate your 'second strike' capability without harming your opponent: just detonate a nuke somewhere harmless (make sure they know about it), and delivering a nuke-sized package to their general vicinity. They'll put two and two together. [Answer] Won't [MAD](https://en.wikipedia.org/wiki/Mutual_assured_destruction) work also in this scenario? > > Mutual assured destruction (MAD) is a doctrine of military strategy and national security policy in which a full-scale use of nuclear weapons by two or more opposing sides would cause the complete annihilation of both the attacker and the defender (see pre-emptive nuclear strike and second strike). It is based on the theory of deterrence, which holds that the threat of using strong weapons against the enemy prevents the enemy's use of those same weapons. The strategy is a form of Nash equilibrium in which, once armed, neither side has any incentive to initiate a conflict or to disarm. > > > There is a point in vaporizing your enemies if you then survive to enjoy the aftermath. If you are granted to get vaporized yourself as a consequence of your hit, there is not much to gain to become a part of quarreling vapors. [Answer] The power to split atoms is not actually very interesting. Splitting a single atom [gives you on the order of 10-11 Joules](https://www.quora.com/How-much-energy-would-splitting-a-single-atom-give-off-and-would-this-vary-as-you-go-through-each-type-of-atom). This fact is why [Einstein originally though nuclear weapons to be impossible](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiLg5aS39vzAhWKg-AKHb_DBqQQwqsBegQIBRAB&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DHD3k1hgbUXQ&usg=AOvVaw0rz0omSphb_c2ieZvqBDfW). In order to do something interesting, you need to split a lot of atoms at once. The ability to split atoms in bulk with a spell seems challenging. You'd need to get the atoms aligned to a variance of less than 10% the radius of the nuclei of the atoms in question and then use a split spell on the exact plane of alignment of the atoms. That's much too difficult. It's much easier is to use alchemy to create fissile isotopes (such as U-235 or plutonium) that can achieve a chain reaction. So, essentially, alchemy replaces refinement of uranium. But now you just have a conventional nuclear bomb (constructed by magical means). Deflecting or destroying projectiles is something that extensive amounts of existing magic would presumably do. Your enemy tries to cast "teleport" on the bomb followed by a "crush" spell to make the uranium go critical? You just cast a second "teleport" at the right time and your enemy gets blown up instead. Or you cast "scatter" or "turn to stone" on the bomb and the bomb is effectively defused. And presumably you have an anti-teleportation field around your army and key cities anyways to prevent enemy fighters from teleporting next to your ranged troops and to [keep your economy functioning](https://worldbuilding.stackexchange.com/q/51444/83464) Additionally, with alchemy in play, nuclear weapons are much more vulnerable to pre-battle sabotage. You have a stash of nuclear bombs ready to use? Better hope an alchemist doesn't sneak in and transmute the payloads to useless gold. Thus, refining uranium could be used for creating power sources for magic. It can also be used to make very dangerous bombs, but these are challenging to use, and only for very specific situations. [Answer] I was going to answer MAD, but that's probably what everyone else is going to answer, so let's think of something else: **strong cultural norms forbid it**. How would a a world that has feudal personal relationships think? Wizarding property is diffused through the world, since with the advent of cost-effective portal tech, one can have their morning coffee au lait under the forged iron arches of the Leffie Tower in Sirap, and then meditate while watching the sunset 10 minutes later in Sol Selegna, half-way across the world. Why would you nuke your own estates? At any point, members of the Ascended families are spread across the world, so nuking this or that city would be a barbarous and crude affair that no Ascend would even deign to consider. This is not without precedent -- some wars in the late 1700s to the mid-1800 had remarkably low civilian casualties. In fact, bitter enemies during the day often have tea in the Sirap salons in the evening together and play cards, and this is seen as completely normal and civilized. Now, tactical usage of nuclear devices on the battlefield on the other hand, is completely within the cultural milieu, and only a moderate step up from FyendFire. [Answer] **Secrecy** Wizards have discovered the secret of the atom but the mundane world hasn't, and they would prefer it remains that way. Using weaponised fission openly would create a lot of questions that wizards don't want to answer, and they also don't want to have to go to war with mundane nations in order to retain whatever benefits they have now. Better to just keep the whole thing under wraps. **Self-policing** Wizards can covertly cull those who they deem too irrational to be entrusted with the responsibility that comes with magical power. In your Hatfield-McCoy example this would mean a third party swoops in and quietly offs the whole lot of them while covering it up. The duties of self-policing would fall onto the greater families(that's why they're "greater", isn't it) while lesser families come and go every generation or so because of their family members ending up in an unmarked grave. [Answer] The spell to split atoms only works at close range. You can perform gold foil experiments all day long, with whatever apparatus is required in your universe, but if you cast the same spell on a chunk of uranium you've got about half a second before turning into vapour. [Answer] MAD is probably the heart of it, but let's see how to get there. If by "splitting the atom" you mean "making fission bombs", then I'd probably go for it being a matter of using magic to compress radioactive material tightly enough to get the chain reaction going. In which case, you can just say it's a range thing -- you can only do it within a short range, which means a magician that compressed enough to go boom would be instantly vaporized in the blast. If they instead compressed multiple lumps such that they are noncritical individually but would go critical when put together, well, that just means they can more easily make nuclear weapons. The rest of the mechanism is still necessary, so it's not like they can point, shoot (er... levitate a few miles away), nuke. It'd be no different than using teleportation or whatever to steal existing nuclear weapons. And that just means that all magic factions are nuclear powers, and MAD keeps them from killing each other. I suspect you may need to further specify what "split the atom" and/or what the risk is that you're worried about. For example, you could enable them to split limited numbers of atoms, producing lethal neutron radiation and/or generating heat for power, but not enough to trigger a chain reaction. [Answer] # If every wizard/ family can easily make nuclear weapons, unless you have a brutal dictatorship nuclear war will happen. Hot headed young people often make stupid decisions, and someone will no doubt decide nuclear weapons is the best choice. You will have a nuclear war. A society where everyone is armed with a nuclear bomb is short lived society. # If the manufacturing of nuclear weapons is restricted to the greater families, they can make treaties and lower the chance of war. Perhaps the manufacturing of purified uranium and the creation of spells to make nuclear weapons is technically complicated enough that only the greatest of families can make them. You need a stronger reason than nukes though. Tactical nuclear weapons have much lower consequences. WW1 notably didn't go into chaos because of a network of alliances. Britain was perfectly capable of ignoring Serbia being invaded, as was France. They couldn't ignore Belgium and France being invaded by Germany, and with the coasts taken Germany could have bombarded Britain freely. Strategic considerations are very important for larger nations. # You need nukes to have negative strategic implications. Perhaps nukes are very effective at taking out magical resources, but not shielded mage compounds. Nuclear radiation could wipe out most native alchemical resources like magical animals and plants, but have little impact on shielded house bunkers. As such, using a nuclear weapon on an enemy means you lose access to many key magical components but that the enemy is still fine and able to prosecute war in their deep underground bunker unless you really nuke them hard. As such, nuclear wars are not strategically useful, and so are generally discouraged. While individuals may have blood feuds, the networks of enforcers each family have will discourage any rogue individual from triggering nukes because of the massive loss of wealth it will cause and the lack of utility against heavily shielded compounds. [Answer] # Nukes Destroy Magic *"I don't understand, master," To'Ril complained, "Why is the knowledge of True Alchemy forbidden? Now that I understand this 'atomic theory', it seems so simple. Split off one proton and two neutrons from each mercury atom, and one has a gold atom."* *"I will show you why," Krin sighed at her apprentice, "他の場所にいる... Teleport."* *To'Ril blinked as he always did after teleportation. Then he blinked again. Before him spread out an empty wasteland. Only scrub grass and small twisted trees. It was silent, perverse.* *"This was once the Forest of Eldin, the great home of the elves," Krin explained, "Until the cursed dwarven alchemist Mahaten decided he would end the final elf-dwarf war by splitting a sphere of lead in the heart of the city. You see, split atoms produces a great deal of heat and energy. It was enough to reduce the forest to this. That alone should be enough for you to understand why this knowledge is forbidden, but it is far worse. 雷電は敵を倒す... Lightning!"* *A familiar bolt of energy shot out of Krin's hand. It was a common attack spell, one of To'Ril's favorite. Only the bolt broke apart and vanished after only ten feet.* *"The child atoms created by splitting the lead are poison," she told him, "Any living creature that spends too much time in the cursed zone will sicken and die. But so to, will the curse eat away at magic. The reason I teleported us here, is that any closer would be impossible. The wasteland is also a zone of anti-magic. No spell will work in there. No blessing will protect you. We cannot cleanse it. From what the best of us can tell, it will be at least four thousand years until the poison has weakened enough for even rudimentary spells to work. That is the price of True Alchemy. Would you pay it, my apprentice?"* The radioactive fallout produced by a nuclear reaction has a secondary effect. It interferes with the binding/weaving of mana into a spell. As a result the area around the nuke effectively becomes an anti-magic zone. Or at least becomes one until enough of the fallout (cursed/poison atoms) have decayed. # Mana Propagates Fission Normally, if one applies enough pressure to induce fission in Uranium 235, the Uranium is the only (or at least the main) element split. Unfortunately, mana, the Nth fundamental force and the energy of magic has different ideas. It causes the fission of not just the initial target, but all atoms within a certain range. Splitting a single Iron atom will near instantly reduce everything in about 200 meters into superheated Hydrogen, and a lot of nasty by products. As well as the commiserate air burst and thermal radiation release from splitting that many atoms. Of course, if there is any oxygen present, then a secondary Hydrogen burn explosion will happen. True, such a reaction can be prevented by removing all mana from the area first. But a spell like that is so draining and complex, the energy would be better spent on attack spells. Splitting the atom is better left forgotten. [Answer] If you can use magic to wield a power as destructive as nukes then it should be possible to wield a power preserving/constructive/protective to fight against it. I don't think any world with magic has magic that is purely destructive unless the entire point of magic is to destroy. Might be quite the spectacle, wizards in an arm-race trying to outmatch each other in best nuke and best shield. The first wizard atom splitter could also have killed themselves in the development and final success of their spell, like a Marie Curie sort of situation. It follows the same line of thinking as to cast a ward or conjure up some other protections before summoning demons or whatever to protect you from their influence. The wizard could have died of their success before being able to share it, preventing wizard nukes for everyone. Yay! This could be gone around by having wizards already know about nukes and radiation and the like and then had protection when they were experimenting but you've not given how educated people are and their general level of scientific knowledge. For that matter most wizards might just be uneducated when it comes to the mundane. How to polymorph without losing sanity? Got a degree for that. How to split atoms? What the heck is an at-tome? [Answer] ## Weather, pest and neutron control. Rain, snow. Flies, cockroaches, and rats. Wizards could summon these things if for some reason they wanted to. More often they prefer to cast a spell to make them disappear. It gets tougher the larger the object, and it is a luckily potent wizard who can unsummon the toddlers from more than one nursery yard at once. But *neutrons*, well, free neutrons are tiny little things, not very common, and all weighed together they wouldn't jiggle a scale. Most people would never even know they were there, and the laws of magic certainly don't account much for them being gone. A wizard can but wave a hand and banish the stray neutrons from here to the horizon. It is little trouble to nuke-proof any land he cares about, and people might be surprised when things come to contretemps just how much land that turns out to be. [Answer] **Access to nuclear weapons is classified information, on pain of death** Only the great families have access to nuclear weapons, and such knowledge is carefully regulated. Rogue wizards attempting to breach this secret are hunted down and killed without further ado. Sufficient proof includes any evidence of study, training, practice, or even unnatural interest in the nuclear rituals. The great families maintain vast networks of spies and fake "knowledge dealers" to ferret out such renegades. The general ban on wizarding nuclear weapons becomes the cultural norm. Naturally, these families maintain a joint agreement not to use nuclear weapons in feuds against each other. It is not in their interest to destroy the society that elevates them to such high status. While in principle the great families could teach it to their rank and file members, common sense dictates that only the most senior and trusted members should be given such an awesome power, capable of destroying their own family along with much of the wizarding world. Wizards with impulsive or hotheaded reputations, however brilliant, need not apply. Only people who believe in maintaining the peace through the delicate nuclear balance of power would be allowed to learn their terrible secrets. **In short, the wizarding world is much like the real world** So long as the power of nuclear weapons is restricted to a small number of powerful groups, it can be controlled. These groups can reach an agreement among themselves to maintain the peace, and work together to prevent the secrets from spreading further. All dread the day when these secrets become so commonplace that any street magician can craft his own nuclear bomb. No one will be able to stop the nuclear apocalypse then. ]
[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 3 years ago. [Improve this question](/posts/177253/edit) (This part is pretty hand-wavy, and only exists to provide context for a fun thought-experiment/fictional story. Feel free to skip to next paragraph) In 1943, the Soviet Union has developed what they believe to be a teleportation device. They can only fit one rifle squad within this device, so they hand-pick an elite squad of volunteers, equip them with loads of ammunition, and test it by attempting to send the volunteers from Moscow to the front. Unbeknownst to them, they had accidentally created a time travel device, that sent the soldiers back in time to 1066 England, the beginning of the reign of William the Conqueror. The device is destroyed in this first use, but the Russians are delivered safely to Medieval England. Being good strong Russian soldiers, they waste little time bemoaning their situation (once they realize what has happened, which will likely take some time to piece together. Like a lot of time) and quickly decide that if life gives you lemons, you might as well set yourselves up as the new rulers of England right? This is a time of political upheaval in England to begin with, and there were already some uprisings against the new king as it was. The question, then, is as follows. Can a single Russian rifle squad use their massive advantage in military technology to outweigh their equally massive disadvantage in numbers, and set themselves up as rulers? All of their weaponry is in good working order, and they are the cream of the crop of the 1943 Russian military. They have extra ammunition, basically as much as they could carry, but have no hope of ever resupplying. They will likely be seen as gods or wizards by many, because of their firepower. Also, it should be possible for them to recruit help, at least at some level, given William's relative unpopularity. The Soviet Rifle Squad is made up of eleven men, armed according to the attached graphic. [![enter image description here](https://i.stack.imgur.com/H04dM.jpg)](https://i.stack.imgur.com/H04dM.jpg) Clearly they have an incredible advantage in any direct fighting with even numbers, and great mobility as compared to any army large enough to fight them. However, they must seek to avoid large scale conflicts that would take all of their ammo to win, because a rifle without bullets is an expensive club. I am looking for political and military strategies they can use to successfully topple William, and set themselves up as rulers. Note: for the purposes of this question, please ignore some of the more obvious problems here, such as language differences, and the issue of diseases being brought back by the Russians and wiping out the continent. Valid concerns, but for this thought experiment I am primarily focused on what military/political strategies the Russians could use, as well as what the best course would be for William to retain his throne. If I have made assumptions or incorrect statements regarding either the Russian element or Medieval element, or if there is extra info that would be helpful, please use the comments and I will edit as soon as I can. This idea of a small modern force seeking to conquer a medieval country has been kicking around in my head for a while now, and I am very curious to hear from some people with more expertise/knowledge than I. Edit: Some "Answers" so far have surrounded the fact that there is a massive numerical disadvantage. This is obvious. If there is in fact no way to overcome this, that's a valid opinion, but what would be the best way to try? I'm fine with them getting a little way and ending in failure, this is actually probably better so as not to disrupt the historical timeline, but what strategy might they attempt? [Answer] *I'll offer an alternative to the majority of 'NO' answers:* Upon arrival, these 11 men would be the most accomplished military force on the planet, with weapons and combat experience garnered from a war the likes of which the medieval world could hardly imagine. Of course, they are seriously outnumbered. The population of England at the time (according to the Domesday book) was reportedly **~1.5 million**. Of course not all of them were soldiers, in fact, at maximum lords could extract 20% of their peasant workforce as primitive troops before famine may become a significant threat due to the lack of farmers. So the Russians could expect to face **300,000 peasants** at max before the country began to collapse due to the shortages in labour forces. Also bare in mind around 1066 the king's military was already stretched fighting the Normans, and the King wasn't exactly popular, and I doubt could get even 20% of the population to fight. The Russians could cause immediate destruction, devastating the feudal system of the time. By starting fires, and killing high-ranking officials, they could terrify local populations, and gain support through tyranny -- something Russians from 1943 were well-versed in. This would involve conserving the use of their weapons, only employing them in front of crowds to exercise authority. High-ranking officials who refuted them would be murdered with alarming speed. By the time news had spread to the king (which travelled at the speed of a horse) the Russians could have exploited the feudal 'pyramid of command', replacing local lords high up the pyramid, and holding reign over a large area of land and peasant population. By forcing lords below them to obey, *immense power could be gained very quickly*. Many have mentioned the language barrier, although I'd point out 'Old English' was divided into numerous dialects at the time, due to the significantly less globalised world. There was no centralised 'English language', making language barriers very common, and not as destructive to politics as some may suggest. It is also fairly common to quickly adopt a native language if surrounded by it -- exchange students use this principle to learn foreign languages at a high speed and quality. The majority of the medieval population was superstitious, and religion was mandatory. If the Russians could frame themselves as prophets, I believe they could manipulate a sizeable proportion of the population by preaching Communism (which I believe would look extremely attractive to a medieval peasant population) instead of Christianity. If the King could somehow withdraw his forces away from the Normans to face against the Russians, they would have already began assembling their own medieval forces. Production of primitive firearms were still not yet viable due to the poor machining techniques of the time, but cannons may have been possible due to their simplicity, should the Russians know the recipe for gunpowder. By the time the King's army finally arrived, word of the Russians would have spread to the surrounding parishes and counties. The King may experience resistance in his own population, and defectors within his army. If the King failed to attack early, his army may well disintegrate entirely. Any attempts to siege the Russians would fail due to the vast area of land they control. The King would be trapped between the Normans and the Russians. If 11 men had prepared to invade **modern** England, they would've brought a lot of ammunition and demolition equipment. If the King attacked, a single machine gun set-up in a defensive position (e.g: castle) could flatten hundreds of men before the King's archers were *even within range*. The King's army most likely, upon being so heavily damaged before even engaging the Russian's army, would collapse and flee (many disloyal medieval forces collapsed under far lighter threats, such as cavalry charges, etc. What about machine guns?) If the King turned up himself, expect him to be sniped. Over the course of many years, the rest of England would be slowly seized from the Normans or the king, through political subversion or direct force. The New Russia would outperform the rest of England in almost every aspect - medicine, agriculture, literacy, manufacturing, and rapidly accelerate towards the Enlightenment era many hundreds of years before its actual occurrence. Of course, the Russian soldiers may not known much about crop rotation, manufacture of penicillin or gunpowder weapons, but simply instructing people to not do [this](https://en.wikipedia.org/wiki/Bloodletting) would go a long way, and you'd be surprised by how much general knowledge we today deem primitive and commonplace would be of immense use to a medieval society. [Answer] As a wily local Baron, I'm skilled in intrigue and deception. As a skilled Feudal warrior myself, I recognize the difference between offensive and defensive weapons and tactics, the proper uses of different weapons, and defenses against those weapons. I'll quickly recognize that these are not gods carrying magic wands. Those are men carrying weapons, powerfully capable, but understandable. I'll easily separate those men from their weapons...likely by using the nearest brothel. There are only 11 of them; they must sleep sometime. Once the group is separated from their weapons, then they are just young men. I'll simply torture one of those soldiers until he shows me how the weapons work. Then some quick knife work and toss the whole squad into a shallow grave. Those secret weapons will, with a bit of intrigue to keep their use secret, guarantee ME the throne! [Answer] ## It depends on Leadership, Ability to Learn, Cunning and Political Acumen So obviously modern era weaponry (even with limited ammunition) will give you a tactical advantage over any one you meet on an individual level. The primary 'purpose' of your weapons in this context is however mainly that **you can force *someone to listen to you or take notice of you*.** That's all. In the time they take notice of you, you need to convince them: * You are worthy of their attention * You are good leadership material for them * You understand their needs now and in the future * You persuade them their future is better if you are their leader, than their current king This will be difficult because of the following challenges which would need to be overcome: * You need to keep your group together. **Leadership needs to be really strong**. All you need is for one of your team to disagree or splinter off to form a rival faction, or have a mental breakdown, and all is lost. * You need to learn their language quickly, and be deft at sensing their customs. **You need a leader that is educated and capable of learning on the fly.** * You need to have a leader that is persuasive, somehow adept at political cunning and acumen, that can persuade disgruntled Lords, Barons and other leadership figures that you can further their own cause by joining you. **You need willing local support that will selfishly follow you (or 'use' you to further their own ambitions).** Historically, many monarchial structures have been overthrown by a lot less, and even by foreign forces and individuals, however the important thing to remember is they need to have local support because they are seen as politically expedient. **Weapons alone will not win a political game, only political cunning in a supporting political environment can.** [Answer] **Failure to plan is planning to fail** This is eleven Russians with awful, terrible weapons. They lose any fight very fast. Seven of the weapons are Mosin-Nagats (M1981/30), a bolt-action rifle with a five-round clip, and I'm going to assume that these are Soviet mass-produced Mosin Nagats to boot, very rough and shoddy weapons. Still could function perfectly fine, but perfectly fine is, again, a five-round clip of a bolt action rifle. The two Tokarovs (SVT-40) are slightly better - it's not bolt-action and it can hold *ten* rounds. The PPSh is a lot more impressive, as it the DT, but they both suffer from problems when it comes to accuracy, not to mention that their rate of fire now works against them - both weapon chew through bullets. A force to be reckoned with against a peasant mob, sure. Even against militia, they'll be useful. However, they lack the ability to perform any kind of meaningful siege, not to mention that on an open battlefield, due to their lack of armor, they're susceptible to massed arrow fire, and they don't have the means to stop them. If they get lucky and manage to find something defensible, they can hold ground, but they can be easily starved out should it come to that. The most viable option is for the company to form a defensive position at the first town they find and hoard the food there in preparation for a siege. At that point, they have a base to defend, and they can prove their worth. Hypothetically, this would give them a negotiating position which they could then leverage to be signed on as a mercenary force. However, that's not the case because they can't communicate due to the language barrier. Not to mention that, given this is 1066, guns don't exist and neither do cannons, so they'll be labeled as magicians of some kind. (The fact that they'll look different from everyone else, given that they're Russian from 1943 won't help.) And, again, given the year 1066, the locals are always up for a good witch hunt. The Russian aren't likely to know English, and even if they do, the version of 1066 is vastly different from the modern equivalent. A broken modern English would be detrimental because all that will do is lead to miscommunication. It's possible that a translator who knew 1066 Russian would be able to communicate with them, but there's no reasonable assumption that a translator who could do that would be nearby, given that Russia wasn't a player in European politics at that time. Ultimately, a lack of preparation and resources on the Russian's part cannot be overcome by applying clever stratagems. The most likely outcome is the majority of the Russian being killed after valiantly attempting a last stand and the last few getting tortured to death by eager Europeans desperate for information on how to create their weapons, and the Russians being unable to respond. [Answer] I'd say that their biggest problems is knowing the language and people and the political situation..etc. But I'd go with something like this: First the goal is to recreate certain modern tech if possible. Medicine, electricity...etc. But the most important one is ammunition actually. As war never changes, you need ammo. So if you can fix that then you can actually have a solid start. I think they were drafted anyway so might as well have an electrical engineer and surgeon...etc But how to take over the country? I can see 3 possible ways. 1. Playing the political game as people do. Claims, royalty...etc 2. Setting themselves as demi gods or angels or something like that. Which is not a fantastic ideas as people are not stupid enough to just believe that because they have a loud tube that can kill people it means they are god. 3. Change the rules. They are Soviets, right? Start a new revolution and using Marxist propaganda they can preach of a new utopia. I'll focus on that. Each path is unique but I think they will lead to the basics of how to rise to power and use it. They start small. Align themselves with a lord or town. Then they help people there using superior military arms and tactics. Like they just try to be a group of mercs and if they kill enough people a lord or a town might hire them. The goal at first is to have a homebase and have loyal followers. Using the Marxist ideas might not be such a bad idea as the masses might be into that more. Now for the fighting, either to defend their land or attack that earl that wants to retake his city, they have to relay on themselves being shock troopers and fight accordingly. I'd say they use something like a testudo and fire from behind the protection of the shields. That way they won't even have to be in any risk. They can also construct something like an armored car. Just metal and wood on a wheeled frame, they actually existed, and they can fire from that safety. But again their greatest ally is actual traditional military tactics. Discipline, maneuvers, superior officers...etc. This is actually an important point as we know that that level of professionalism is not something too common back in the day. So if they can produce actual competent officers then even a 1 to 1 battle will end in their favor as their officers are much quicker on their feet. Again here is a good place to start creating early cannons and early firearms. The above inventions would radically change their armament and guarantee their superiority. And again they actually know how to use firearms and cannons, even early ones. So no more having trouble with coordination between cavalry, artillery, and infantry. No more not understanding how weather conditions gunpowder or that you aim for the center of mass. And especially training the men to actually shoot and kill, none of that shot above the enemies crap. So just inventing a competent army with WWII theory would change the world. The first city is of course the hardest. But after that it's simply a matter of organization. Copy the Soviet formula. Create the party, have a crap ton of spies to the point of having 1 in every 3 people being one, control the entire state, fund massive public projects, control the food and the farms...etc. This is not about supporting the USSR, Marx, or Stalin. I'm merely talking about history and what is logical for a group of USSR soldiers to do. Anyway as I was saying trying to create a whole new regime is not that hard if you actually have a group of people with enough skill and intelligence to start it. Appeal to people with popular ideas and images. Hire the disgruntled and utilize those landless and powerless. Creating a core of fanatic believers is, again, tough at first. But we all know that a single German political with a good enough oratory skill plunged the entire continent into absolute chaos. Also as the question too broad I'm trying to answer it in broad manners. The actual tactics and political maneuvering has to be based on the context [Answer] # No. First, that squad and the mission. The clever thing to send would be saboteurs, not a regular rifle squad. Instead of rifles and a LMG, [pistols](https://en.wikipedia.org/wiki/Welrod) and lots and lots of [timed](https://en.wikipedia.org/wiki/Pencil_detonator) incendiaries. Or perhaps German uniforms and regulation sidearms. By then the Soviets had plenty of samples. Next, the skillset. The Soviets would know that they're sending people of a kamikaze mission. The soldiers might also know, and agree anyway, as long as there was a marginal chance of survival. Frontline infantry didn't have a long life expectancy, either. There might be someone from the [NKVD](https://en.wikipedia.org/wiki/Welrod) in the team, perhaps even someone with covert ops experience in Berlin. But no really skilled political manipulator, either. They would not send a skilled mechanic or engineer because those people are needed for other jobs. The best chance would be if the Soviets **thought** they had an one-way time travel machine, and selected/trained/equipped a squad to visit Ivan the Terrible or Peter the Great to "take over" and "uplift" Russia. A few reliable (in communist eyes) political operators, physicians, engineers, and their bodyguards, with a cargo of textbooks and plans. The malfunction would be in distance (time). The team as described would be * unable to set up ammunition production, once their initial stocks are used up, * unable to speak the local language, * unable to turn advanced scientific and technical knowledge into benefits on the ground. You know that [Penicillin](https://en.wikipedia.org/wiki/Penicillin) comes from moulds, right? Do you know how to produce it? Black powder is saltpeter, sulfur, and charcoal. Do you know how to turn a centerfire rifle into a flintlock? --- *Follow-Up:* # How to suspend disbelief There is a saying in various games/speculative fiction, "primitive does not mean stupid." But assume that several of the time travelers are **very** well versed in Marxist-Leninist theory, and actually have a better understanding of the fundamental economic conditions in 11th century England than the local Englishmen. So they introduce the economic aspects of early industrialization, from division of labour instead of individual master artisans to double-entry bookkeeping. They understand things like inflation, interest, depreciation of assets, etc. The squad contains a riverboat mechanic and a machinist. Together you technobabble that they come up with a viable steam engine, which helps a former coal miner to seriously overturn mining. [Answer] Francisco Pizarro conquered Peru with a few men, primitive firearms, no supply line, against a native army of 100 thousand warriors and without knowing language, culture or geography. So, it can be done if you are brave and cunning enough. [Answer] There are a number of problems facing the squad (ignoring disease and language barriers)- namely lack of manpower, lack of historical, political and geographic understanding, lack of money and distrust from locals. The first problem is going to be that they are massively outnumbered, and without any support units providing reconnaissance and intelligence, it is going to be fairly easy for an enemy force to surprise the squad. Given their limited ammo supply and the fact that WW2 weapons were not that accurate, they probably aren't going to want to open fire beyond 400m. A galloping horse can travel at around 25m/s, meaning that they would have around 15 seconds to break the charge before they get overrun if attacked by cavalry. Given that there is only one machine gun in the squad (and the DP-27 was generally issued with a 47 round drum) and they don't have enough men to create a dense 360 degree protection, a determined cavalry charge by a few hundred horsemen from multiple directions will split their fire enough that it will most likely succeed and wipe them out. **Pure force, therefore, is not going to cut it**. It is going to take savvy and political knowledge to be successful, and there is no guarantee that the squad will have any. Most of your squad will likely not have any knowledge of 1066 England, however given that this is a hand picked unit, it's not beyond the question that some of them may have higher education- history and politics degrees will probably be the most useful. However, they still will lack any connections or knowledge of the local area they find themselves in. The local population is probably going to be distrustful of strange men with strange accents, weapons and uniforms, so recruiting locals is going to be difficult- especially as the average peasant probably just wants to keep their head down and feed their family. One possible approach is that they present themselves to a lord and offer to work in their service. Under the right circumstances, they are going to have a massive advantage over their enemies (especially if supported by period troops to protect their flanks), so any lord trying to carve out their territory, deal with local insurrections or topple the king would happily take them in to their service. **If a talented sniper is sent back as part of the squad, they alone would be a huge asset to lords as assassins.** This would give them a foot in the door to build connections, and develop their own strength and loyal troops. After winning over the trust of enough knights and noblemen, they could launch a coup and seize control or try and earn a castle and lordship through service. Extending their control beyond a single region is going to be difficult, however, as with only 10 men they cannot project force far enough by themselves and will rely on local forces to do that. They will inevitably be seen as 'upjumped common soldiers', not noblemen, so they cannot guarantee any loyalty or fealty from local nobles once they leave the area- you would probably need a Russian squad in every castle to control it and the surrounding area in anything other than name. Arguably, their best chance to win complete control of the country is to ride on the waves of a rebellion against William the Conqueror, using their own weapons and skills sparingly in decisive battles, and rely more on the local forces they have built up. Should the rebellion succeed, they could take advantage of the instability to eliminate their opponents and claim the throne for themselves. However, this is a long shot at best, with the most likely 'good scenario' being that they establish themselves as minor Lords with small areas of lands and influence. [Answer] Their reception would depend on their exact location and time of the year. The situation in some remote rural location would be very different from that in a large town, but either way one big problem would be time. Whatever demonstration of power was made might well have to be repeated as news would not be telegraphed far and wide very quickly and would get garbled. Things would tend to happen very slowly by modern standards as there are few roads and limited long distance travel. They have to walk everywhere until they can find enough horses and some or most of them probably don’t know how to ride a horse. In 1066 the local population would not be an uneducated equivalent of twentieth century people. They would have a very different outlook and environment. 1066 was before the enlightenment and people would not be open to manipulation in the same way that people might be today, yet would be open to manipulation in ways that people aren’t open to today. But the Russians would be unlikely to know how to deal with people for their best advantage. The Russians would more likely be seen as demons than magicians under such circumstances and generate fear amongst the people. Knowledge of history and theology would probably be as useful as the guns. It would be very difficult to engage with people due to massive practical difficulties in language, culture and religion. For example Old English and Norman French would be totally unrecognisable to modern English and French ears let alone Russian ears. Another problem when they did start dealing with people in authority would be the necessity to deal with them at close quarters where dangers might lurk behind every corner or curtain and all food and drink would be suspect. At longer range arrows and stones might arrive from unexpected directions at any time. Eventually their ammunition would become exhausted or their weapons would get damaged or accidents would lead to injury infection and death, or they would go mad. [Answer] ## Snipers at the Battle of Hastings [![enter image description here](https://i.stack.imgur.com/EurXP.jpg)](https://i.stack.imgur.com/EurXP.jpg) In Jan 1066 [King Edward the Confessor dies childless](https://en.wikipedia.org/wiki/Edward_the_Confessor). A powerful earl, [Harold Godwinson](https://en.wikipedia.org/wiki/Harold_Godwinson), claims that Edward appointed him to be king of England on his deathbed. Maybe Edward did. Maybe he didn't. Nevertheless the King of Norway decides to invade. He's supported in intelligence and favor-building by Harold's own brother Tostig. In September 1066, the King of Norway's forces (about 10,000 soldiers) land in England. Harold puts together a mob of about 3,000 peasants and maybe another 1,500 recruits. In the battles of [Fulford](https://en.wikipedia.org/wiki/Battle_of_Fulford) the Norwegian King kills almost all of the hastily-recruited English militia, but a few days later at [Samford Bridge](https://en.wikipedia.org/wiki/Battle_of_Stamford_Bridge), a significantly strengthened (10,000 footmen + 2,000 cavalry) English army routes the King of Norway, killing most (8,000) of the assembled invasion force. Two weeks later William or Normandy crosses the English Channel with between 3,000 and 12,000 troops. Half of these are footmen, a quarter longbowmen (but don't be impressed, during the fighting the were injured by slingshots and thrown rocks from the other side), and a quarter armored cavalry (but again don't be impressed because the armor was ridiculously flimsy and they were taken down by axes). Harold Godwinson, calling himself the King of England, puts together another militia of anywhere between 3,000 and 12,000 troops (somewhere between 6,000 and 24,000 total combatants). William is harassing Harold's peasants and disrupting commerce, so Harold rushes out to meet him. In a full day of fighting, [about 10,000 soldiers are put into their graves](https://www.telegraph.co.uk/news/earth/environment/archaeology/9632922/Are-bodies-of-10000-lost-warriors-from-Battle-of-Hastings-buried-in-this-field.html). Harold is killed by "an arrow" during the fighting. William's cavalry and archers are hacked to bits by slingshots, spears and axes. After a night-time English rally fails to finish William off, the exhausted English vanish into the wilderness, allowing William's force to take the throne. ## неуместны во времени [![enter image description here](https://i.stack.imgur.com/bFSlO.png)](https://i.stack.imgur.com/bFSlO.png) With a [published range of 547 yards for the M1891](https://www.militaryfactory.com/smallarms/detail.asp?smallarms_id=276), the Soviet rifle squad could pick any target at the Battle of Hastings at a stand-off range from the combat. Assuming a member of the squad knew about this battle, the squad leader could have chosen to take out both William and Harold from the marshes. There are no contemporary images of William, but likely both leaders were taking a very active role in keeping their dispirited fighters fighting, and might have been easy to pick out. After all the butchery was done, you had a few thousand English and a few thousand out-of-place Normans who were probably all eager to go home. A full can (47 rounds) or an extended can (63 rounds) from the DP machine gun could put any re-organizing resistance into the dirt. The [DP has a published effective range of 874 yards](https://en.wikipedia.org/wiki/Degtyaryov_machine_gun), so your rifle squad doesn't even need to expose themselves to harm to take out any troops that aren't going home. However, you may not even need to do that. The key persons on both sides are dead, and the armies have nothing to do. And who is really going to think some weirdos standing in the marsh had anything to do with the kings' deaths? The Soviet rifle squad could just walk away. ## The March to London / Stalin's Solution to Dukes Most government was by duke. And most duchal household's security was a few knights among the family, and the ability to rally their peasants. Stalin recognized a similar rallying power of wealthy farmers in Russia. Recognizing it as a threat to the revolution, he sent men with guns into their homes to kill them. The next step for your rifle squad would be to, before word could spread, travel to the nearest duchal households. A peasant would kick in the doors, and drawn out the knight(s). Although people were familiar with gunpowder, bulletproof knightly armor would not exist for another three centuries. A rifleman would take out the knight(s) and any other defenders at range. The element of surprise keeps the dukes from having time to rally their citizens to defend the house. The dukes would need to be replaced with loyal men the Soviet squad had picked out of whatever local followers they'd gathered. With a few days work, you could manufacture supportive nobles in the territories from Hastings to London. ## Regrouping After becoming King, your group may have a problem. The Pope is influential, and was supportive of William. However, the nobles were no sticklers for royal blood : William himself was an illegitimate child. How well the rifle squad held on to power would depend greatly on how they managed the political climate of the times. [Answer] This essentially the premise of 1632 / Ring of Fire, just in a difference in scale. Whereas the 1632 series had thousands, these people do not. They'd last maybe a week or so before succumbing to disease or locals. As was pointed out, ammunition is not infinite, nor are primers. This is the modern Achilles heel of all firearms. Since they don't have any mercury fulminate or knowledge of manufacturing alternative 'green' primers (Chlorates), their guns are just unwieldy clubs once they inevitably run out of ammunition. ]
[Question] [ In trying to both invent and prevent mediums with which opposing armies can defeat "Army X", I come to you, stack exchange, hoping for some second-opinions on how to 'defeat an immortal army'. In essence; "How does an army equipped with standard blades and shields (and the etc that comes with it) ultimately defeat, or otherwise fend off invaders who are immortal?" I wish to find novel ways to deal with them, or to patch up loopholes, that I'd like to see removed, with new conditions. Conditions: **1.** Army X is immortal. Its soldiers can be 'killed' temporarily, but will be spontaneously revived after a few seconds where they fell with their wounds removed, including but not limited to dismemberment, beheading, etc. **2.** Those individuals in Army X who find their bodies 'stuck' (such as in a pit, chained, etc) can instead opt to resurrect inside of a suit of armor elsewhere in the world. The same goes for bodies otherwise completely and irreversibly destroyed. Note that said armor is specially designed and constructed, meant solely to house said dead warrior of Army X should they be faced with a trapped original body. Said armors are located only in their capital city. A warrior of Army X that has undergone this transfer in no longer flesh and blood, but rather a walking animated suit of armor from then on. **3.** The medium with which Army X maintains their immortality is through a single individual living within an 'impenetrable city' (which could be a discussion for another time). For all tends and purposes in this question, this healer cannot be killed, or their powers otherwise nullified. **4.** Each member of Army X is, in essence, a 'hero'. They are the sort of character capable of fending off a great number of enemy grunts single-handedly. No other nation possesses the capacity to create anywhere near as many soldiers of the same caliber. **5.** Though the enemies of Army X do possess the capacity for spell-slinging, for this question consider them incapable of magic; I'm looking for other solutions to defeating/fending off the army than magic. **6.** Soldiers of Army X do need food and water, but can be revived regardless of death from starvation/thirst. 7. Soldiers of Army X die from old age, and are not revived upon doing so. They cannot, however, be afflicted to grow older faster (due to magic, for example). To reiterate **What sort of tactics/strategy could an army with mundane medieval weaponry utilize to defeat or otherwise fend off invading Army X?** **EDIT** Based on comments/responses, I'd like to point out that the apparent unstoppability of Army X is *completely intentional*. Army X is meant (at least, for a time) to be unstoppable. For the world in question, their unstoppability does not last, but I wanted to explore any possible ways I hadn't considered before that they could still be defeated. Condition 3, namely, is the medium by which their unstoppability is lost. [Answer] Hope you invested in the sciences before you were attacked. The trick to defeating this army is to incapacitate without inflicting lethal wounds. You could maim them, but that would still give them the opportunity to suicide and spawn again. So, how do we defeat a hostile force without inflicting bodily harm? Incapacitate them. Something that is fast-acting and can be applied on the battlefield, that persists after initial exposure, but doesn't cause undo harm to our own troops or generally have a lethal effect on victims. Chemical weapons come to mind. But not something intended to be lethal, like mustard gas or the other ugly compounds banned by the Geneva accords. What about a sleep agent? [Chloroform](https://en.wikipedia.org/wiki/Chloroform) has gained notoriety in crime dramas for quickly putting people to sleep, but the science [doesn't support that](https://en.wikipedia.org/wiki/Chloroform#Criminal_use). But chloroform as we have been led to understand it acts like a particular other substance, namely, [sleeping gas](https://en.wikipedia.org/wiki/Sleeping_gas). Sleeping gas is a generic term for an inhaled substance that induces an unconscious state in victims, and there are plenty of real-world examples for this. [BZ gas](https://en.wikipedia.org/wiki/3-Quinuclidinyl_benzilate), for example, is a military-grade sleep agent. Of course, being military grade, the production process isn't public knowledge. Instead, let's look at [methoxylflurane](https://en.wikipedia.org/wiki/Methoxyflurane). This gas can induce pain relief in 3-mL doses for up 30 minutes at a time, and sedation in 6-mL doses. It takes just 6 to 8 breaths for effects to kick in. So, if we were to construct a projectile weapon containing methoxylflurane and unleashed it on the army, we could incapacitate huge swaths of the invaders. Once the soldiers are incapacitated, we can tie them up and ship them off to parts unknown. An army of 5,000 isn't an army if each soldier is in a different location. Mandatory Caution Notice: [Fluorine](https://en.wikipedia.org/wiki/Fluorine) is a dangerous substance that likes to react with just about everything. Many researchers died trying to isolate fluorine due to complications with [hydrofluoric acid](https://en.wikipedia.org/wiki/Hydrofluoric_acid). Researchers and soldiers alike should take precautions when dealing with methoxylflurane. Mandatory Warning: Some subjects of methoxylflurane may die due to complications arising from overdosing and medical preconditions. While collecting the incapacitated, be wary of soldiers feigning sleep or rousing early. [Answer] Given everything that you've stated... You don't. With them reviving a few *seconds* after death, this means that any sort of "close" battle - The only real option - is a defeat for normal troopers. Consider this: Normally, you could sit inside your walled city and be... OK-ish. With Army X? They can literally just take catapults and fling their guys over. Sure, they'll die. Then they'll resurrect. You can defeat *individuals* via capture, but you simply can't capture an entire army that doesn't want to be captured. A single immortal who cares nothing for death could kill many, many normal people before they get overwhelmed and captured, and that's a war of attrition the normal people cannot win. The immortals are at full strength pretty much all the time, while normal soldiers have to be able to resupply their losses. Now, if the Immortals revived after **hours** and/or something a lot easier like decapitation forced them to revive at their home city, you could push them back by forcing them to revive significantly further away. You'd also be able to steal their stuff, which I'm assuming isn't as easily replaced. [Answer] The only viable way is to destroy or circumvent the command and control system. Your soldiers are (ridiculously) hard to destroy, so they're simply not a viable target. Targeting them would be to attack the enemy at the strongest point, which is bad tactics. There is, by the way, a serious flaw with them : if you can't kill them, it will surely become apparent to the soldiers themselves that they should be giving orders, not taking them. What happens when they run out of "official" enemies ? These types aren't going to all retire to gardening and church socials, they're going to want to take over. You'd quite likely end up with a lot of warlords fighting endlessly with each other and rife with internal dissent. But they have to be controlled, or they're just useless grunts. Someone has to direct them in a strategic way : what do they do and who to. So you'd use covert or down-right sneaky methods to infiltrate and attack their communications. You'd ideally attack select senior commanders or the political leaders. You'd interfere with their lines of communications. And even if they are willing to die because they instantly get recreated whole, there's a difference between dying repeatedly by desperate enemies who have no option but to fight you, and being willing to suffer all that pain and misery for an endless battle. This is particularly the case when they split into factions and start internal battles. And note that because they are essentially invincible, they'll rapidly start to view everyone else as irrelevant, slaves at best, useless at worst. That's another problem : they're a warrior caste and the only worthy enemy for them is their own kind. Another possibility is that, as a warrior caste they actually develop an ethic that's it's dishonorable (or similar) to battle mortal opponents. That might limit their willingness to fight. Likewise, killing and being killed is a messy and emotionally exhausting business, even if you're invincible. Killing mortals is pointless - it's just easy - so will they suffer battle fatigue ? Even the best soldiers can suffer battle fatigue. Will they start asking questions like "why are we doing this ?". Maybe they *will* want to retire to more productive lives. In WW1 there was a notable instance where the exhausted (but still brave) French army went on strike for better conditions (which they got at some sacrificial cost). Would a peace movement break out ? There were many instances of front lines developing a live-and-let-live mentality : we won't bother you if you don't bother us. During the American Civil War there was a case where soldiers declined an opportunity to shoot at opposing officers in the distance (out inspecting their own lines) because they regarded it as murder. Would your soldiers start viewing killing mortals as plain old nasty murder and simply stop doing it ? Again, maybe you can "turn" them (or enough of them) with some cleverly directed propaganda. Maybe you'll convince some units will decide that *defending* mortals is more honorable than killing them. Maybe you'll convince them that you're no threat to them (and you're not) and they'll look for more challenging enemies (other immortals). Maybe you'll simply bribe them : we'll pay you more than the idiots you're working for now, wine, women, song. So there are ways to attack them, it's just that the weapons you need are not blades, but perhaps words. [Answer] Three ideas spring to mind. * One - Psychological warfare. You win if you convince them to stop attacking you. I have no idea what this would look like in your world, but mind-games, propaganda, illusion magic, diplomacy, or lies - any of this could be an effective attack vector. Find their fears and prey on them, or find their desires and tempt them. Give 'em what they want and hope they leave. They do have a goal, right? As long as it's not 'eradication of all life', giving it to them is obviously worth serious consideration. * Two - keep them alive. So, they can respawn elsewhere if their dead body is trapped. Alright, but can they kill themselves? If you can capture them while denying them the ability to respawn, they're stuck until they die of old age. Drugs and maiming are your friends here. After their capture, I'd suggest combining this strategy with point one above, and attacking their mind while you have control of their body; addiction, brainwashing, sensory deprivation, or just good old torture... It's definitely possible to break some people's will, and although their body might be immortal, it doesn't do them much good if they spend the rest of their life cowering under their bed. * Three - build a better wall. So each of them is a hero - okay. But the defender has a definite advantage, and unless they have unlimited resources and strength, there must be barriers they can't overcome. Use a mountaintop castle or a lava moat or a flying island. Move off-planet, move to a different dimension. They respawn elsewhere if their entire body is destroyed, so the most you have to do to repel them is create a defense that guarantees the destruction of their entire body, make sure you have no viable respawn points inside, (store all armor in separate pieces) and they won't be getting in. Well... There are possibly more solutions, depending on how you define 'wounds', 'armor', and 'total destruction of their bodies'. (Ship of Theseus arguments.) Is being sliced in half a wound, or total destruction? If they respawn without wounds or scars, do they respawn without immunity? Is being sick a 'wound' they can heal from? Using plague that you're immune to but they're not might be worthwhile, even if it just weakens them enough to make capturing them easier, for points 1 & 2. Would bleeding to death from ebola count as 'total destruction'? Infect their water. Or maybe a viciously painful poison on your weapons would work, something like box jellyfish venom. Even if they kill themselves, as long as the poison remains, they might not be willing to resurrect in the same body. [Answer] The first step here is to remember the single most important rule of war. No other rule is more important: > > The goal of war is not to make your opponent lose. The goal of war is to make yourself win, and barring that, make yourself not lose. > > > Your mundane army surely has a purpose. They have something they want to fight for. They probably want to get back to farming their fields and raising families. If your mundane army's goal is to make Army X lose, then they have failed the first rule of war, and are going to lose no matter how creative we get. Got it? Good. Now, there is a loophole to work with here. Their respawn rules are simple: 1. They can respawn in the same body 2. They can respawn back in their city 3. Where they respawn is their choice This provides the natural solution: we need to make sure that infinitely respawning warriors at those two locations isn't unacceptable. Make sure you can achieve your win condition despite an infinite army respawning and then go about your business. The simplest solution is to pin them back into their city. This wont be easy. You might try grappling them rather than killing them, so you can push them backwards or drag them back to their city. Breaking large numbers of bones may be an effective approach. Whatever approach you take, you want to reduce the area they have to work with. This limits their resources. Once you have the resource of the entire shared kingdoms of your planet, and they have the resources of a single city, you are no longer on such shaky ground. Now it is time for a new rule. We started with rule number one. Now we'll skip a few, to rule 37: > > Rule 37: There is no "overkill." There is only "open fire" and "I need to reload." - [Schlock Mercenary](http://www.schlockmercenary.com/2004-02-23) > > > The city may be impenetrable, but the surrounding land isn't... yet. Your job is to weaponize a kill zone so ungodly that no Army X soldier will ever get the privilege of respawning within the kill zone. They will be obliged to respawn back at home base. I recommend lots of flamethrowers. Maybe some really big mosquitos too, if the flamethrowers aren't cutting it. I hear Minnesota has some good ones. From there, war just becomes part of life. You have a general rotation of soldiers which man the flaming-killzone-of-doom for a few months and then rotate back. You have an entire world to police with. From there, it's up to you as the builder of this world. How much can life suck for Army X before they decide maybe they should talk to us instead of fight us. [Answer] I am drawn to this key word and tricky phrase: > > can instead opt to resurrect inside of a suit of armor elsewhere in the world. > > > --- ‘Army X does indeed have one weakness, m'lord: Those suits of armor which they wear seem to be the source of their vital powers. Removing the armor from one living seems impossible by our assessments; if, however, we can distract the army long enough to sneak a few of our stealthiest soldiers behind their lines, we might be able to discover a way to destroy their foundries and reserves of armor. ‘Then, it is simply a matter of trapping the others in lidded tanks filled with oil. ‘Our losses will be numerous, but the sacrifices must be made. They are, after all, peons, and we are nobles.’ [Answer] I'm not exactly sure how aging affects your soldiers, but I always thought humans don't die of age but of your bodys failure to cope with all the stuff that's killing you. Diseases, Injuries, damaged cells that can't be copied any more, etc. I'm not a biologist so take it with a grain of salt. :) Since they can revive and regain lost body parts I have to assume it is a rather crude will based process and not based on "last state of your body before death". If it was they would not regain body parts lost before their death, but only those causing it. If it was not "crude" they would be able to fix the damage aging does too. If it was some kind of save point they create of their body before death to regain once they died you got a leverage here. They'd loose memory of the time after creating the save point once they respawn. Since their brain would regain it's former state. Crucial information gathered that must not be lost could force them to "save" even when wounded. But I'm not sure how that process works for you so I won't detail this further. Can they get sick? If they were struck with an infected blade, would their revival still have them carry that infection? If they can, you could infect them with a disease that weakens their bodies. Not killing but weakening and reducing morale. If it is a bacterial infection you could argue that it does not get removed as it is a live form within them and no wound. Since they need food you could also poison that. Nothing lethal but more crippling things. Maybe something that makes it hard to breathe, resulting in severely weaker troops. They'd have to suicide to get healthy again, if revival even removed the poisoning. Knocking them out. You could just use something non lethal to knock them out. Gas maybe? Then feed them with means that allow them to stay unconcious. IV bag maybe? :) Then just feed them for their lifespan in a big prison like the matrix. The matrix (or something similar) would be viable too, but since you wanted them to fight with swords, shields and magic I assumed the setting would be more medieval. It doesn't stop you from using hallocinogenic stuff though. Make them think they fight/whatever by using alchemy/magic/drugs. Since they eat and drink you could use drugs as an alternative for poisoning the water/food. Does respawning clear addictions? Be cruel and make them addicted to something only you can provide. A formula only stored in the head of an alchemist? They can't take it by force (if the alchemist does not succumb to torture). [Answer] Yeah... A mundane medieval army is at huge disadvantage against this Army X. It's just not possible to do any lasting harm to them or deprive them of any significant amount of important resources. And there's no magical way to stop them, like summoning a bigger fish or holding the whole world hostage. Which leaves few paths to the victory open, one of them being to # Surrender to the Army X And after that, use non-military means to make holding you and your resources bad for them. If those sword and shields can't bring you a victory, just don't use them at all, and don't waste your people in the process. Use them in another way, applying social and economical pressure against the Army X that the winner of the war wouldn't be able to avoid. Like: * Assimilate Army X "heroes" into your culture. So in the next war, they'll actually be fighting on your side. * Steal their young. If they have to live among you to control the conquered territory, take their children and raise them to fight their parents. * Organize ongoing non-violent civil resistance movement against Army X. Let your people refuse to obey any laws of their making, any orders that they give. Make them spend lots of time and effort to get anything done. Manipulate them into committing atrocities against your people when they try to enforce any semblance of order. If they are civilized and enlightened, they won't be able to handle it, and they'll go away by themselves. If not, the mages of your world may come to your aid, so the Army X advantage against you will be neutralized. * Sabotage producing any food on your land. Make Army X feed your people, or face the unpleasant consequences of the previous method. [Answer] Assuming that the mundane army is forced into conflict… I'm sure those tactics could be more or less handled, still I have to state how one would try to deal with immortal warriors. While in given situation such an army would wipe out any enemy in open battle, the weakness of such army still lies in a few factors, which can be used: * Stamina, sooner or later they will need to rest. That is when they are most susceptible for attack. Their ability to act will be also reduced when exposed to starvation or/and dehydration. The point is to capture them before they will die. * Immortality, make them wish to die, cripple them in any monstrous way it's possible to imagine and allow them to get revived in their capital as useless mindbroken wreckage if magic will not counter any mind-shattering. Such soldiers will be useless and will not be able to reproduce as they will be just set of fancy armor, meaning less heroes to be born. The matter of question at this point is: do those 'living armors' feel pain or fatigue? If not, it would be easier need to keep captive soldiers alive just without limbs to make sure they will not escape as 'living armors' that would still be able to act at war would definitely seek for revenge, while flesh'n'blood soldiers would be more likely to distance themselves from danger of sharing fate of such an armor. * Subjugation, including mind-control, brain washing, psychological warfare and similar techniques. Even in medieval times there were effective techniques of breaking one's mind and fighting spirit. That technique would prove especially effective against 'living armors' that would be captured in ambushes. If armors wouldn't 'feel' it could be easy to cut off their vision and hearing by closing their heads (meaning helmets) restrained in some containers. It could prove useful due to fact that space needed to constrain such an armor would be comparatively little (helmet needed) and would quickly lead living armor's mind into madness as people are unable to psychologically withstand sensory lockout. * Slowing down, while immortal immortal army still has shape close to human so it's possible to catch one in standard pits and traps. Also even living armor will have to slow down when traveling thorough difficult terrain. * Economy, production of armor and equipment that may be ditched at will, especially when it's magical is costly. Whether one would be able to subsequently catch enough of immortal warriors it could disrupt state's economy while providing (at worst case) recycle material for it's enemies. * Destruction, use swift attacks to destroy lands and villages of enemy to destabilize lives of their citizens. Calls for retaliation unless destruction is more localized and performed by spies. Agents may destroy immortal army support and disrupt it's standing in state or command chains. * Infiltration, get access to vulnerable points and attempt to destroy enemy from inside. * Politics, maybe no other nation may have so many heroes, but how about all neighbors? * Research, capturing enough magical armors create own or hijack captured ones into battle golems in attempt to effectively out-tank enemy or create own immortal warriors only with more 'respawn' mages. * Burn it all, when mentioning magical armor, it means there is some magical prowess. Use battle mages or other means of effective and complete destruction. While warriors may be immortal, they may be forced into respawning as armor so they will need some time and means of transportation to come back at battlefront. Note, that proposed ways of fighting need ways to perform backstage actions, stability or possibility to equalize chances of fighting by reducing numbers or strength of enemy dealt at once. Edit: *In case it wasn't clear, due to ability to jump into 'living armor' when shackled (let's assume transfer may be performed at will) it becomes nearly impossible to capture and tricky to torture immortal soldiers unless transfer may be somehow delayed. Still it could be possible to disable armor senses by taking off it's helmet and this way force transfer, which could be disabled by ability of sorts 'phantom body', which would need only a little tweak to the general idea of living armor.* As for killing the most important pillar of immortal army, it is sure that all the countries would attempt to kill one on the spot whenever the information would leak to them. Still nobody said that there is really only one 'respawn' mage and as sad as it sounds it calls for real-time soul-crashing defeat when mundane army gets to feel the victory in their grasp… As nobody is really irreplaceable. Also as it was stated by M i ech there are many ways to make advantage of immortal army setting to make it even worse enemy unless one will successfully make them turn against their master who would probably would just need to revoke their personal immortality and immortalize some other citizens. This makes coup d' etat a bit more tricky than normal. [Answer] As other answers put it, mere mortals can't win (in this battle). So don't give battle. War is politics with weapons, according to [Carl von Clausewitz](https://en.wikipedia.org/wiki/Carl_von_Clausewitz). So keep politicking without weapons, as long as needed. Intrigues anyone? But you didn't tell why they fight. Nor the political organisations. So this is all I can tell. [Answer] # Radiation induced Cancer Since the only way to get your soldiers to die is of old age, then you have to kill them with cancer or heart disease. Force-feeding them bacon doesn't seem like it would work that well, but cancer is the kind of thing you can non-consensually inflict on a nearby immortal soldier. If you have wizards on your side (which I don't see why not, immortal armies seem pretty magical) then you can heavily irradiate the enemy soldiers. Send your soldiers into battle with blade tips magically coated with something radioactive and nasty ([polonium?](https://xkcd.com/965/)). A few stab wounds, and some deposited radioactive materials, and then beat a hasty retreat. You can expect the immortal soldiers to die of 'old age' in a few weeks. Tritium would do the trick, or Caesium-137, Iodine-131, and Strontium-90 all have nasty cancer causing effects. Alternately, you can use a spell of 'Summon Proton Beam' to irradiate your enemies from afar, preferably the safe confines of your castle walls. The same kind of beams that are used for radiation therapy can be pretty effective if directed at important things you only have one of, like your liver, or brain. If wizards are expected to throw fireballs and summon lightning, I wouldn't consider gamma ray sniping to be too outlandish. [Answer] **Hurt** them. So they can't be killed, or they respawn. So they will heal of injuries when they respawn. So they can't be trapped, because they can escape while respawning. Do not let them respawn. Keep them alive. You do not need be so *merciful*. Cause, well, there's nothing at all, at all, in the rules that say it doesn't *hurt* to be injured, to be trapped, to die. Nothing that says injuries to the heart or mind or soul heal like injuries to the body. Practically, you don't fight them head on, you ambush scattered groups in any way possible, at overwhelming odds and with any trap available, take prisoners, and move on to capture the next lot. And you take them prisoner, trap them living, strap them down, and **hurt** them. Can you induce PTSD? Can your traumatize them? Break their morale, their courage, their confidence? Can you do your level best that, if and when they slip out of your hands and respawn far away, they will look at their leaders exhorting them back into battle with you and *despair*? Or maybeso *hate* those leaders driving them back to that duty, that risk? Or *fear* falling back into your hands? You can't permanently take them off the field, but you can do much to make them want to take themselves off. Make them reluctant to go back to war, hesitant (or at best, incapable due to trauma) of going back to the battlefield. They revive whole, so they wouldn't "need" that much of a reprieve before being sent back within reach of their torturers. To be fair, this is going to *also* make them hate you, and want to hurt you back. They will have no mercy, not after this. But if it's the only chance you've got, if you know how to hate and how to fear, maybe you can persuade them you're not a palatable target, you can make yourselves more trouble than you're worth. Maybe. As a bonus, give them a way out... maybe if they surrender *instead* of fight, they get time at a decent POW camp, instead of the torturers. Maybe if you find deserters of theirs, you treat them decently or offer shelter. Let their foot soldiers wonder, at every ambush, if they should lay down their arms and be treated well, or stand their ground and, if loosing, suffer for it. And maybe do something extra about higher-ups... maybe lighter treatment, or automatically sent to the decent POW camps, so their foot soldiers resent those ordering them about, safe and risking little while their own suffer. Maybe, if you're lucky, convince the officers that you don't treat them all that bad, maybe those foot soldiers who reported otherwise were malingering. Or maybe very carefully separating them from their soldiers, never talking about what happens to them or admitting that you have them at all, and gently and with all healing skill crippling them or sending them into comas, so their officers once taken just *disappear* and are not heard from again. Teach them fear, when they don't know what's happening, when they don't know why their officers never return or if you found some way around the magic respawning. [Answer] ## As multiple other people said, you don't. **Worse. Depending on details of respawn mechanism, you can never defeat them. Not even with your plot idea.** **You imply, later on you will assasinate the being that heals them. You won't.** You said they respawn in seconds. If they find themselves trapped, they can ditch the body and respawn inside armour. Problem is, if they decide what means trapped, they can pretty much opt to just respawn themselves instead of walking down the hall. Because it's faster that way, system like that begs to be abused. ## In this part I'm assuming you mean specially designed and built magic armour. In that case, they have ultimate strategic mobility. It's as easy as building armour to easily open in front, so respawnee can walk out and they can easily hop to any place they can bring armour to. One army can handle all the fronts at the same time - while enemy will spend weeks marching, they can just station army in capital, and ferry wagons with respawn armour everywhere. As soon as they near enemy, army hops to the location, and after they drown enemy in their bodies (don't care about attrition), they hop back. They don't even need weapons. They just need to rush enemy, dying over and over again, swamp enemy and take their weapons. Doesn't matter if they die thousands times each before they steal one sword, they are still making progress. This is also why you will never defeat them. **All their locations are defended at all times** (stock weapons in cities to avoid wasting time on stealing enemy weapons) **and they can rely messages instantly**. You will never get close to the capital. You have no chance to sneak small group to attack the capital, because **you CAN'T tie their forces at all** and if you somehow coordinate attack, hundred kilometres apart to try, they just need to send one respawnee to recall forces back to capital - they don't care about losing ground, they can take it back without effort. You can't assassinate that being, because there's no reason to ever have non-"immortals" in same district, or even same city as that being - Immortals can be servants while they are not actively fighting. Use spwan-hopping to handle diplomacy, if you ever want to talk to the inferior kingdoms, and make it crystal clear that envoys stay the hell out of capital. ## While in this part, I'm assuming you mean any armour. This is something that turned up in comment discussion with Cort Ammon. If you mean they can spawn inside any empty suit of armour, or channel Agent Smith and take over body of anyone wearing armour, then it's even worse. Your Army X wins war against everyone before anyone even knows there's a war. As soon as being creates first regiment, they perform decapitation attack on nearby kingdom. Since they have FTL communication (using respawning couriers), while everyone else has to rely on couriers on horses, they can simply decapitate next kingdom before news even reach them. Thus, they can decapitate every kingdom in the world (all nations used some form of armour, at least ceremonial and as status symbol, good enough for Army X) before anyone can even figure out what's going on. If in your world there's magic allowing to talk at distance, other kingdoms may get a warning fo Army X, but they still won't have time to muster any form of defence - calling together feudal armies tended to take a lot of time and any suit of armour, in every feudal lords armoury is a spawn point - if King gets warning and somehow manages to get his subjects to disassemble all armour in his castle, all his vassals can still be subverted and used to stage assault on capital, when convenient. No hurry. They have probably about a month to decapitate as many kingdoms as possible, before they have to worry about those who escaped initial strikes. **Reading your question, I think it's even worse than you planned for.** [Answer] So your Army X cannot be defeated in combat. Let's face it: **it just won't work.** If cou cannot win a fight, don't fight it. It's as simple as that. You could offer them something in return for not having to fight. But okay. You want a battle. Because we all know that you cannot have a story about an invincible army if you don't have a fight. Narrativium demands it, so we have no choice. Well, of course we do have a choice, if only a choice of weapons. Do your Army-X-soldiers feel pain? If so, make sure they unterstand that you can make their immortal life very, very unpleasant. That might make them think twice. **Play bagpipes.** Nobody likes the sound of bagpipes. Threaten them to play for as long as the battle lasts. They will either kill you (and the bagpiper) on the spot, ending the problem for you immediately, or realize that immortality is really a bad idea when you have to spend a lifetime near a bagpipe player. Of course you could always accept the fact that immortal armies are boring. But that would eb a different story. [Answer] There are a few ways to defeat such an army. What you're basically saying is they're unkillable and can teleport out of situation they don't want to be in. Here's two ways: Sleeping darts. Capture them with sleeping darts/gas whatever and then keep them in a perpetual coma. Wouldn't it be cool if the Terracotta Army was actually an unkillable army, put into a coma only to be found 100s of years later? What if they wake up in the modern days? Drugs. Get the opposing army addicted to drugs/narcotics you only own so their addiction overcomes the control their master has and they work for you in exchange for the next "shot". [Answer] **Get them Drunk!** Not really a way to defeat them, but at least keep them immobile for a while, would be to spike their drinks/water with alcohol. Granted, the amount of alcohol that would be required to keep them blacked out drunk for an extended length of time would be quite large, but this would fulfill all the requirements for keeping them out of the fight, yet unable to transfer their bodies. When they are very inebriated, transferring their consciousness would be something beyond their mental state and could potentially reduce them to stumbling, easy'ish to control sacks of meat. A good by-product of this would be that it might lead to some infighting between the immortal soldiers, however once dead, they would be sober again, so this would be a continual effort to get/keep them drunk. This could also be done by challenging them to a drinking contest. A few of your soldiers getting alcohol poisoning, is a small price to pay. [Answer] I think the drugging/gassing solution is the best. After that here are a few alternatives. Starvation. Burn everything edible, and poison every well within X (10-30) many days from the healer’s base. So they die of dehydration before they get anywhere, and get resurrected back in the center of the poison desert. Fill in the suit of armor. (Concrete) Throw the armor into the ocean. Capture their family or those they care about. Build impregnable defenses. Build a defense that one person can hold. Be nomadic so the enemy can’t get you. Deploy Mongolian horse carvery. (Better bows, with longer range on better horses with more stamina, with better riders). [Answer] You can't without losing the battleground. You have to make the battleground lethal through chemicals or radiation (anything that produces continuing lethal damage). That way they can die and respawn continuously. Eventually, the enemy will stop sending troops into your area. So, they would just go around unless you completely surround your self with a thick band of lethal land. I don't know if I would consider that a win. [Answer] Since you did not specify them being immune to poison gas that is clearly the way to go. I mean even if they resurrect instantly the poison does not go anywhere and they will just cycle between death and resurrection. Start by tricking them into a valley. This will contain the gas and make sustaining the effect much easier. The best is if you can make them camp for the night there. Treachery is your friend when dealing with immortals. Opiates or other narcotics. You want them to be too confused to opt for resurrection to an armor outside the effect. Drugging food and water is probably the best as burning gives a distinct smell they might notice. You do not want to kill them just stop them from noticing the actual poison. [Carbon monoxide](https://en.wikipedia.org/wiki/Carbon_monoxide). It is a "colorless, odorless, and tasteless gas that is slightly less dense than air". In other words it is exactly what we want. And you can produce it simply by burning things with insufficient air, no advanced technology or science required. While the immortals will revive after carbon monoxide kills them, they will not resurrect any wiser than they died. If you can pump the carbon monoxide level high enough which by the way also implies low oxygen level, they will not have time to understand what is going on and decide to revive elsewhere. They will be very confused. And they cannot detect what is killing them. For that matter I would not be surprised if the revive was not fully effective in this case. It seems reasonable that it will fix the damage caused by poisoning but does it replenish the amount of oxygen in your blood? Or actually remove the poison? I doubt it does. It is mentioned they eat and drink and why would they do that if the magic sustaining them could replenish their energy, water, and oxygen? This will work much better if you can either trick them to buildings that can be made air tight or can move them into such using golems or magically protected workers. I mean eventually you will have a storm with winds strong enough to clear the poison. You can of course protect the entire area with a magical field. [Answer] With all those rules, I thought of torture, since that doesn't kill them, and saps their will to fight... but that would classify as being stuck, and they could just abandon their bodies and take up a suit of the armour. However, if they are rendered unconscious and are kept that way with a bit of primitive brain surgery, they will neither be dead nor stuck in a situation from which they have the mental capacity to desire escape. It may cost the lives of hundreds to capture each immortal, but while troop quality is important, it can be trumped by quantity. Then, the immortals are rendered unconscious and made to be incapable of desiring escape yet not dead, and are kept alive until they die of old age. Faced with an army that is dwindling yet the soldiers don't come back either - neither dead or desirous of escape - the immortals will find themselves becoming increasingly irrelevant. [Answer] First of all, a terminology correction: Someone who exclusively fights people of vastly inferior skill, using lethal force against people who have absolutely no hope of retaliating in kind, is in no way, shape or form a hero. They're bullies at best, and likely cowards -- it's no feat of courage to fear people who can't kill you or even permanently harm you. Second, you're doing an amazing job of railroading every possible way that they could lose away, but that's your decision to make, so I'll point at the loophole you missed: ## "You'd be amazed at what you can live through..." If you're up against a force of unkillable bullies, and Option Zero ("Don't have a battle") isn't available, what you're going to have to do is throw out the entire rulebook about Laws of War, Rules of Engagement, and especially the parts about 'cruel and unusual', 'inhumane' and 'war crimes'. They can't die, but they can still *hurt*, and they do still have a morale that can break. Go all out VietCong -- booby traps under every bush, aimed to hurt and maim rather than kill. Sure, they'll be back momentarily, but if enough of them keep dying in screaming agony before reviving then sooner or later they'll want to pick a fight with someone who 'fights fair' -- meaning a fight they don't risk losing -- instead. [Answer] **Cleansing fire** Immortal soldiers who spring back up from the grave, wounds fully healed, are a very difficult problem. As they are also 'heroic', they can kill a slew of 'normal' soldiers if they try to swarm them and just keep stabbing the immortal to death. You need something better. Fire is the answer. It is low tech, incredibly painful and relatively easy to administer. The pain should in general also take the one on fire out of the battle. It leaves nasty wounds and if hot enough the skin itself can burn. This last bit is important. Make sure the person is set on fire hot enough that they keep burning. They die. They revive. The fire has again fuel to keep on burning. Basically this cycle of burning and dying repeats until cooled off enough, oxygen has been taken away or the soldier stops reviving and goes to the armor. How to do it? Many nations would have access to torches and flaming arrows. This in itself is already good, but the presents of torches and flame arrows often means oil as well. More refined oils can be created, burning hotter and brighter, but might not be needed. Now that you've got something that can burn hot and bright, you start chucking it against the enemy. This can be done like Molotov cocktails, or just throwing oil over the enemy and then lighting them on fire with torches. Other advantages are that you don't need direct hits, as splashes can already throw the (burning) oil against the enemy. Glancing hits are also very good. If there is any doubt that they will keep burning, you just keep throwing on more oil. Once the burning death cycle starts, it'll be relatively easy to keep administering oil and it is very likely few immortals want to come back more than once. It is insanely painful. If they do, they might get mad and lose usefulness to the immortal empire. This will cost a ton of manpower. Oil in those times is difficult to produce, as well as torches and the like. In battle many will still die, as the immortals are heroic people and being send against them is still a death sentence for many. But this way they have a chance. You'll likely support your oil throwers with a double line of long spear men, holding the heroes at a long distance and buying time to raise hell. Behind the oil throwers you'll have bowmen with fire arrows to just add to the fire for all oil that isn't ignited yet. The deaths that they cause can also help with more time, as well as speeding up the fire/death cycle. The suits of armor require a different approach, but as they seem to be unable to resurrect a simple overpowering force is all that is required, using numbers and brute force to overpower them and then hammer them into unusable shapes. [Answer] I think it'd have to be a propaganda war, in the hopes you can get some of the immortals to turn traitor. Somewhat cliché, I know, but it's the most likely way of defeating them... surely all the immortal soldiers aren't thrilled at massacring defenseless folk, so you'd have to use that against them somehow. As bad as it is, sending out child soldiers might be their best bet, that is bound to cause some dissention in the enemy ranks - unless they're essentially drones, but I didn't see mention of that in the question so I'm assuming otherwise. It sounds like their only flaw is their immoral actions, so that would be the best place to focus your strategy, making the soldiers themselves realise that this is the case, otherwise I think you're just banging your head against a wall. [Answer] Your best option is to take out the ruler of this army. Create strife and disorder. These are soldiers, they follow orders. If no one is ordering them around, they might just go home. The best case scenario is a civil war. It would literally go on forever, or until they died of age. Problem solved. Another way would be to drive them insane, and release them. They would not re spawn, because they are still alive, but nor would they be a threat. [Answer] Well, since you can't really defeat per se your best bet would probably be slow it down, and incapacitate in some way. Someone already mentioned various sleeping gasses, but if this is Medieval level technology and those aren't available you could go for spikes on the ground, leg hold traps, snares etc. For a more long term solution one may try to find some terrain that is especially easy to defend. I don't know what your world is like, but if there is a way to say, go across a massive river and destroy the bridges behind you, you can then leave a bunch of forces watching the river, whose task isn't to kill the enemy solders, but to thwart their attempts to rebuild the bridge. Or hole up somewhere in the mountains, where you can keep throwing rocks down to keep knocking the enemy down, etc. Basically any terrain that is difficult to get through and where being a strong warrior isn't really relevant. Based on the comments it seems like they will respawn in the home base, inside a specially created armor if the body is destroyed, which does provide some options. For example, if you can lure them into some narrow area (Castle entrance or such) and then pour in some burning oil you can send a lot of them back at once. They'll respawn, but it will take them some time to get back and it might put a strain on their special-armor-production facilities, whatever they are. In any case you buy yourself some time to evacuate/hide, setup more traps, etc. Ultimately, given the setup the most rational course of action would be to find methods to delay the enemy while you escape, since you can't really beat them [Answer] ## Feint The number of soldiers in Army X is finite. [Stonewall Jackson](https://www.youtube.com/watch?v=wCgi9BNjj6c) kept an army of 50 thousand invaders busy chasing him in the mountains (and essentially neutralized because they were far from the real fighting) by threatening the capital with, initially only 5 thousand of his own men in the [Shenandoah Valley Campaign](https://en.wikipedia.org/wiki/Jackson%27s_Valley_campaign). The weakness of Army X being exploited here is that they are: finite, and still only have limited knowledge of where and when the enemy is attacking. For all they know, the force exploiting the mountain pass to attack the Army X capitol really is the main force. ## Overbear Immortality does not increase the force multiplier for Army X to $ 1 : \infty $. Let's look at the guaranteed takedown case for any one soldier in Army X. One "friendly" soldier can die on Army X's blades, while 3 or 4 peers knockdown and tie up the Army X soldier. So, the force multiplier is $1:5$. A defender with 5 times as many soldiers as Army X in a particular field engagement has a reasonable expectation of winning at 20% loss of life. There's usually a rule-of-thumb of $1:3$ for defenders, so I believe these stack such that a non-Army X attacker will probably need 15 times the number of troops to win against dug-in Army X positions. But it is still a feat that can be done. True, Army X can re-spawn at the Army X capitol, but it takes some amount of time to get back to the front. They are beaten for this engagement. ## Defeat in Detail Every successful General from Alexander the Great to Vice Admiral Hiroki Abe uses a combination of feint and overbear to take apart armies many times their size, by choosing to attack the enemy where the attacker possesses a numerical advantage. This is called [Defeat in Detail](https://en.wikipedia.org/wiki/Defeat_in_detail). We've determined that against unentrenched Army X targets, a force of 5000 ordinary soldiers attacking Army X scout group of 500 has every reason to expect victory, for a loss on their side of about 500. This can be repeated several times, taking down an Army X force expeditionary force of 2,500 if done in five 500-man chunks. This can scale to any arbitrary size with reinforcements among the ordinary soldiers. The weakness being exploited here is that Army X soldiers are merely immortal, not all-strong. ## Nets Nets are a staple weapon in ancient armies, and will be very effective against Army X. The net comes in many form factors, but the one I imagine that would be most successful is metal links and lead weights and an attached line. It is a team weapon : one or two soldiers throw the net on a target and the rest of the team pulls the line to take the target off his feet, tighten the envelope, and tangle the target. This weapon would be effective even if Army X also had “the strength of 5 men”, because a solid metal link net requires a lot more strength than even that to break out of. ]
[Question] [ What kind of asteroid would it take to hit our sun out of its current position, even by just 50 meters? And how big does it need to be in order for it to do so? Would it continue to travel through space after being knocked out of our system, or is this simply not possible? If so: What size asteroid would be able to 'shatter' the sun? [Answer] **tl;dr: It can't be done.** Meteors and all the various different classifications of them (meteorites, meteoroids) are small. The sun is big. More importantly, the sun is hot. If a meteor is heading for the sun, not only would it do almost nothing when it hits, it would be vaporised long before it hits. **However, in theory:** Let's assume you have a meteor 100 tons in mass. That's 100,000kg. Let's say it's travelling pretty fast, $3 \times 10^5 \text{ms}^{-1}$We can work out how much momentum it has: $$ \text{momentum (kgms}^{-1})= \text{mass (kg)} \times \text{velocity (ms}^{-1}) $$ $$ = 100,000 \times (3 \times 10^5) $$ $$ = 3 \times 10^{10} \text{ kgms}^{-1} $$ The Sun has a mass of $1.989 \times 10^{30} \text{kg}$. Therefore, if we divide the two we can find the resulting velocity of the Sun after impact: $$ \frac{3\times 10^{10}}{1.989\times 10^{30}} $$ $$ = 1.508\times 10^{-20} \text{ ms}^{-1} $$ $$ = 0.00000000000000000001508 \text{ ms}^{-1} $$ It is important to note that this same math applies to a vaporised asteroid as conservation of momentum still applies; however, if some of the vaporised material **passes** the Sun, it won't affect it. However, as shown in [this article](http://www.stuff.co.nz/science/9457374/ISON-Comet-vaporised-by-sun), this is unlikely as the acceleration of dispersion is not enough to disperse the material sufficiently before reaching the Sun. So even a fairly "heavy" meteor only results in the Sun moving at a fraction of a metre per second, at which speed its gravity would keep all the planets in orbit with it. Lastly, it is impossible to "shatter" the sun, as it is made of gas and would simply part and reform around an asteroid. [Answer] Something the other answers seem to have missed and I will focus on is: > > would "it" (the Sun) continue to travel through space after being knocked out of our system > > > Let's ignore the impracticalities of moving the Sun and focus on what would happen once the Sun starts moving. The answer is also not a lot would happen. For a start, our Sun is already moving, along with the rest our solar system, at 230 km/s around the "Galactic Central Point". This "Galactic Central Point" is the galaxy's centre of mass, just like the moons of Jupiter, or the planets of our Sun, all stars in our galaxy are orbiting this centre of mass. So when we talk about moving the Sun, what we really mean is significantly altering its orbital speed. This would change our path around the galaxy, but the consequences of that may not be seen for millions of years and are therefore difficult to predict. But due too the vast emptiness of interstellar space, there is a high chance nothing would happen. That is if you ignore the effects of something large enough to change the Suns course in the first place. As has already been pointed out by other answers, you need something massive to influence the Sun. Jupiter is the second largest object in our solar system, its mass alone is 2.5 times larger than the rest of our solar system combined. It's so massive that it forces our solar system's centre of mass outside of the Sun, if only slightly (Our moon has a similar, but much smaller effect on us). But as massive as Jupiter is, slamming it into the Sun will hardly affect its orbital velocity (as already pointed out). So we're going to need something bigger than the biggest planet in the solar system and this is where we run into tangible problems for Earth. As I already pointed out, Jupiter is so big that it moves the centre of the solar system, anything that big entering the inner solar system, on a direct collision course with the Sun, is much more likely to disrupt our orbit before it disrupts the Sun. This new gravity source could alter our path, taking us out of the habitable zone, perhaps making the planet too hot or cold too support life for much longer. It could even elongate our orbit enough to put our highest point into the asteroid belt where the planets surface would be bombarded by asteroids. Worst case Earth could even be accelerated out of the solar system. In short if anything big enough to affect the Sun ever comes that close to the Sun, we are probably already dead. Where the Sun goes, the rest of the solar system follows, unless another force disrupts the planets orbits. [Answer] Technically, everything would cause the sun to move, whether we have the ability to measure or see its effects are something different. Every object in the solar system causes an attraction due to gravity and mass. The sun would move towards the planet slightly less as it's mass is larger, but it is attracted and does move towards the planets slightly. This is called the stars wobble. This is the principle used initially when we began really looking for planets outside of our solar system. [Answer] If we strech the definition of asteroid well past what is reasonable. Jupiter has an orbital energy of $1.544×10^{35} J$. [WolframAlpha](http://www.wolframalpha.com/input/?i=orbital%20energy%20of%20jupiter) So if we crash Jupiter into the sun(deorbiting it by magic) in a inelastic collision we will impart 8.6 m/s of velocity. [WolframAlpha](http://www.wolframalpha.com/input/?i=%28root%20of%20%28orbital%20energy%20of%20jupiter%2Fmass%20of%20Jupiter%29%29*%28mass%20of%20Jupiter%2F%28mass%20of%20Sun%2Bmass%20of%20Jupiter%29%29) This corresponds to a 0.029% change in the earths orbital velocity. [WolframAlpha](http://www.wolframalpha.com/input/?i=%28%28root%20of%20%28orbital%20energy%20of%20jupiter%2Fmass%20of%20Jupiter%29%29*%28mass%20of%20Jupiter%2F%28mass%20of%20Sun%2Bmass%20of%20Jupiter%29%29%29%2Fspeed%20of%20earth) I have no idea how noticable this would be. The effects from the sudden lack of Jupiter would definitly be more noticable. [Answer] It will not happen, no matter how big a meteorite is. Now, some data: A meteorite is a rock that has fallen to Earth from space, so it can not impact Sun at all. Meteors are the traces of falling stars on sky. So I'll talk about **meteoroids** for the remaining of the answer. (Check [Meteoroid at Wikipedia](http://en.wikipedia.org/wiki/Meteoroid)) Sun's mass is $(1.98855±0.00025)×10^{30} \text{ kg}$, while meteoroids are, by definition, smaller than 1m size. Such a small rock will not even be noticed by Sun. **EDIT** Now that the question asks about asteroids... Biggest asteroid in the Solar System is [Ceres](http://en.wikipedia.org/wiki/Ceres_(dwarf_planet)), currently classified as a dwarf planet like Pluto. Ceres' mass is $(9.43±0.07)×10^{20} \text{ kg}$ (ten orders of magnitude less that Sun's). On its own, [Eris](http://en.wikipedia.org/wiki/Eris_(dwarf_planet)), which is the biggest dwarf planet (bigger than Pluto), has a mass of $(1.67±0.02)×10^{22} \text{ kg}$, 8 orders of magnitude less than Sun's mass (this is a hundred millions times minor). It will simply not move the Sun at all. [Answer] The answer is not impact, but gravitational attraction. The Sun is a giant ball of **gas**. If you launch a meteorite of a "magical" material strong enough to survive its interior, and with speed/aerodinamics enough that it does not get slowed down by friction (another thing that is easier said than done, given its size), such meteorite would emerge at the opposite side (although with, probably, some deviation). If you want to move the Sun, you want to pull something massive near it and have it attract the Sun. Of course, such a massive object would also affect the planet orbits by itself, so I do not think you would get the Sun to move away from the planets (most likely, the planets will end crashing in the new object). [Answer] This reminded me of an xkcd what-if. <https://what-if.xkcd.com/20/> lots of people here saying that it's impossible but that's not strictly true, an asteroid going close enough to the speed of light could absolutely do something bad to the sun. It may have to be going at 99.9999999[keep adding 9's until you get enough] % of the speed of light but eventually you hit a point where the energy it hits the sun with is enough to cause something catastrophic... unfortunately the speeds/energy involved would have to be so insanely huge that it would be almost impossible to come up with something even vaguely plausible that could get the asteroid moving fast enough. [Answer] In order to move the Sun, we have two basic requirements: 1. **Deliver enough momentum to the Sun to move it.** I'll start with enough to get it moving $1~\text{km}/\text{s}$. Not very fast, but let's just see what happens. The momentum is just $p=mv=2.0\times 10^{33}~\text{kg}\cdot\text{m}/\text{s}$ 2. **Deliver little enough energy to the Sun so it is not destroyed.** As an absolute upper estimate, I'll use the [gravitational binding energy](http://en.wikipedia.org/wiki/Gravitational_binding_energy), which, for the Sun, is about $T=2.3\times 10^{41}~\text{J}$ (about 20 million years of solar output). We just have $p=mv$ and $T=\frac 12mv^2$. Just by dividing those equations we get: $$ v=\frac{2T}{p}= 2.3\times 10^8~\text{m}/\text{s}=0.76~c\\ m=\frac{p^2}{2T}= 8.7\times 10^{24}~\text{kg}=1.45~\text{M}\_\text{Earth} $$ Ok, I see really high speeds which means we need to take relativity into account. Fiddling with the [proper equations](http://en.wikipedia.org/wiki/Kinetic_energy#Relativistic_kinetic_energy_of_rigid_bodies) gives us: $$ v= \left(\frac{p}{2T}+\frac{T}{2pc^2}\right)^{-1} = 2.0\times 10^8~\text{m}/\text{s}=0.67~c\\ m= \frac{p^2}{2T}-\frac{T}{2c^2}= 7.4\times 10^{24}~\text{kg}=1.24~\text{M}\_\text{Earth} $$ For a more reasonable Sun's speed of $100~\text{km}/\text{s}$ the minimum mass goes up to: $$ v= \left(\frac{p}{2T}+\frac{T}{2pc^2}\right)^{-1} = 2.3\times 10^6~\text{m}/\text{s}=0.76\%~c\\ m= \frac{p^2}{2T}-\frac{T}{2c^2}= 8.7\times 10^{28}~\text{kg}=4.4\%~\text{M}\_\text{Sun} $$ (Remember, this represents an absolute minimum mass required. You'll have to go with something heavier (and therefore slower) to avoid punching right through the Sun.) So you're not looking at an asteroid, but more like shooting a dwarf star into the sun at a speed of $2000~\text{km}/\text{s}$. Good luck with that! [Answer] Pea-sized. That's what size asteroid can move the sun, but, not in the way you expect. First though, an asteroid implies something that is currently traveling through space in a typical fashion. What would a typical object do when crashing in to the sun? Fist, it will be moving the sun long before it 'hits'. Gravitational effects will cause both objects to accelerate toward each other. Due to it's mass, the sun's acceleration will be significantly less than the asteroid's, but it will move. The question is really whether the impacting force (in the opposite direction) is more or less than the cumulative effects of the force that was exerted in the opposite direction before the impact. That largely depends on the velocity of the object before it entered the gravitational boundary of the sun (where the gravitational pull of the sun is more assertive than the pull of the rest of the universe). In turn, that implies that the asteroid is on a collision course long before it enters the cosmographical boundary which is on the far side of [the Oort cloud](http://en.wikipedia.org/wiki/Oort_cloud) - 50,000 to 100,000 or more Astronomical units away. (Pluto is up to 50AU from the sun). Something that is 'pulled' in to the sun through its gravity, will not ever be going fast enough for the impact forces to outweigh the forces that were exerted before the impact. Note that this happens regularly. In fact, it is how the sun was created. Additionally, comets regularly impact the sun. They have no measurable effect on the suns position (though they can produce spectacular solar flares). Something that is 'shot' in to the sun may. But also, something shot in to the sun would simply pass through it, unless it burned up first. Something bigger than the sun? (or close to the same size) Well, that's interesting, because then the logic all gets reversed, and you really should talk about our sun being shot in to it, not the other way around. The bottom line is that there's no way for an object to have any significant impact on the sun without being so huge that it will pull all the planets out of place before it gets to the sun, or it is 'fired' in to the sun from outside the solar system (it would be impossible to fire something like that from inside the system) ]
[Question] [ Hear hear, with the latest arcane technology, archers on the battlefield are able to shoot "smart arrows". Smart arrows are **propelled** by a little unit of magiteck, which allows the archer to control the arrow' movements finely. This includes **sharp turns**, sudden **accelerations**, and the ability to bypass **obstacles** or **shields**. Experienced magiteck archers are said to be able to obtain such a fine level of control on their projectiles that they can **center a knight's helmet eye-slits** from 200 meters distance. In the modern battlefield, traditional archer squadrons used to battering down the enemy with a constant rain of arrows are slowly being replaced by "smart archers", with a lower rate of fire, but an unparalleled ability to make every arrow count. Please keep in mind that: * The magiteck propeller on each arrow has limited power, meaning the arrow cannot keep going forever and will run out of power after around 5 seconds from being triggered. * The common practice among smart archers is to activate the propeller just before landing, to *kill a specific target*, *correct aim*, or just *increase dramatically the piercing power*. * While smart arrows cannot pierce well made plate, their added power makes them dangerous against any lighter armor. Experienced archers will often targets joints, holes, or other weak spots. * Smart archers need to see the arrow in order to control it. While the effective range of arrows might be around 300m, those are not usually able to leverage the greater accuracy. [![a smart archer.](https://i.stack.imgur.com/gZZYu.jpg)](https://i.stack.imgur.com/gZZYu.jpg) An example of controlled arrow on a small distance: [x](https://tenor.com/view/yondu-take-out-whistle-marvel-comics-guarduans-of-the-galaxy-gif-17296452) Would armor evolve in this context? What defensive measures would an army take against such archers? [Answer] **First, let's look at the limits of your technology** Medieval war bows had tremendous draw weights. Estimates of 180 lbs are not uncommon. (I've drawn a 100 lbs. bow. It's a *difficult draw* if you're not trained to it.) And they threw heavy arrows — nothing at all like our modern hunting arrows. While one or two claims of 300 fps hover in the Internet aether, most people believe your average arrow speed was about 180 fps (55 mps). Now... you have *magic arrows.* One wonders why bows are even involved. Maybe they aren't! You don't say, but even if they're not, everything I just said has value. Why? An effective range of 300 meters means at traditional speeds the archer has 5.5 seconds to affect their plan — and the target has 5.5 seconds to do something about it. But here's the kicker... In the heat and chaos of battle these little itty-bitty-zippy arrows will be impossible to see. And you have only 5.5 seconds max to use them. And that's on a good day. And if you let the arrows move faster, you simply rob your archers of the time needed to control the arrows. **Habits are hard to break** Generalizing something awful, medieval archers massed their fire. > > Volley fire, as a military tactic, is (in its simplest form) the concept of having soldiers shoot in the same direction en masse. In practice, it often consists of having a line of soldiers all discharge their weapons simultaneously at the enemy forces on command, known as "firing a volley", followed by more lines of soldiers repeating the same maneuver in turns. This is usually to compensate for the inaccuracy, slow rate of fire (as many early ranged weapons took a long time and much effort to reload), limited effective range and stopping power of individual weapons, which often requires a massed saturation attack to be effective. > > > ... > > > The term "volley" came from Middle French volée, substantivation of the verb voler, which in turns came from Latin volare, both meaning "to fly", referring to the pre-firearm practice of archers mass-shooting into the air to shower their enemy with arrows. ([Source](https://en.wikipedia.org/wiki/Volley_fire)) > > > Now they have a new technology! But it actually takes time to change how everybody thinks (from the archers to their commanders to their kings...). As soon as the new technology becomes difficult to use (distance, fog of war...) everybody will return to what they know best: volley fire. Granted, with the magic arrows this would be *devastating,* but it's still an advantage to the defenders. If they can make the situation confusing for the archers, the archers will return to known tactics. It's just human nature (unless you're talking about 30-50 years of experience, but that's unrealistic due to continuing innovation in both magic and technology). **So, what can they do?** 1. Press the attack. Get as close to the archers as possible to nullify the value of the magic arrows. Archers were usually a distance away so they were safe while they volleyed their arrows. The problem with your magic arrows is that for every meter lost to the approaching horde the archers lose 0.02 seconds of reaction time. It doesn't sound like much, but it adds up fast in a battle. 2. Try to fight during twilight when the archer's mid-distance vision will be blurry. If you can't finagle twilight, try to force their archers to face the sun. 3. Shift to speedy and agile cavalry rather than slow and predictable infantry. Become harder to hit. Then train your cavalry to make frequent pattern changes. In fact, it might be useful to study the pattern races used during an [O-Mok-See](https://www.omoksee.com/rules.html). 4. Change your armor to include channels or shaped paths (think "skateboard park") so that the arrow must hit dead-on to penetrate and, if it doesn't, it gets deflected to useful places, like along toward the hips and the ground. 5. *Camouflage!* Wear cloth outside the armor that's a bit billowy and the color of the surrounding landscape. 6. Master fighting in the rain. Funny thing about rainstorms, it's darker, the rain is obfuscating, and people randomly slip. Since it affects both sets of infantry and/or cavalry identically, it's a major blow to the archers. **Finally, use fire to fight fire** 7. Using the promise of wealth beyond the dreams of avarice for success and pain beyond the mien of Lucifer for failure, motivate your own mages to work out how to cast *Dispel Magic.* It's too easy to design the magic arrows to be godlike. Godlike is boring. The only way to defeat godlike is to create a flaw. An "Achilles Heel," if you would. The effective range of medieval arrows was about 140-300 meters, depending on the weight of the arrow. I'd favor 200 over 300 meters. Or... Give up on the idea that your archers can accurately see *and track* the eye slits of medieval armor at 200 meters. Remember, heat and chaos of battle. Fog of war. It's unrealistic to believe that even a practiced archer could do that on anything other than a stationary dummy during practice. Thus, it's the more easiest way to introduce an imperfection that balances the magic system. [Answer] 1: Electron… magic warfare. Like with smart munitions, you add magical nodes that can disrupt smart arrows, if not hijack them. Your arrows will veer off-course, you just lose control or the arrow will suddenly be controlled by an opponent who starts singing the battle hymn of “Return to Sender”. And that does not even consider the potential to activate a smart arrow in a quiver and steer it before the owner is even aware they're screwed. 2.1: decoys So your opponent can hit you, but those arrows won’t come cheap. Have a bunch of fake targets, like half a dozen dummy officers, prance around the field. Have fun when a bunch of expensive and likely limited supply smart arrows hit a dummy. 2.2: dazzle patterns In a similar vein, but on your body. Dazzle patterns are designed to make it hard to judge distance or the exact position of something. When every soldier had a pattern on their helmet that makes it look like there’s several vision slits it becomes much harder to concentrate and hit the real one. Having a mass of lines in a group of soldiers would even make it harder to target an individual soldier, making it virtually impossible to target specific vulnerabilities. 3: counter-smart fire. I mean what self-respecting officer wants to stand outside in bright colors so their soldiers can recognize that their orders are genuine when some lowly archer might kill them? Send small groups of smart arrow archers out first who target smart arrow users. Another thing to consider: it's almost impossible to judge where an arrow came from in the heat of battle. Most officers and nobles would not want to put the power to kill them without anyone knowing in just anyone’s hands. So the pool of people to actually get these arrows might be purposefully limited. 4: hide. Using fire and smoke you can make it hard to see. Or use the scenery. You can also proliferate more moving barriers for example to hide the exact position of people and their vulnerable area’s. 5: hull down. So everything else has failed and a smart arrow is coming for you. Hull down lets you protect the vulnerabilities in your armor. For example you go on your knees and place your shield on the ground and the top at your temple. Can’t really hit the vision slots when there’s not even space for the arrow to approach and enter it! Having some things like a completely closed off visor could similarly make you go hull-down. [Answer] > > Smart archers need to see the arrow in order to control it > > > Smoke screens and anything which prevents the mages from seeing the target will work pretty well as defense against them, making their arrows not worse than conventional arrows. Additionally the attached army can try blinding the mages by using reflective surfaces to shine their face with the sunlight, or placing themselves with the sun behind them, again preventing them from seeing the arrows. [Answer] **Deception.** (I.e., dummies) Military deception has a longer history than the [Wikipedia article](https://en.wikipedia.org/wiki/Military_dummy) might suggest. The obvious famous one being the so called Trojan Horse. At 200 yards, no-one is going to be able to tell a well-made 2 dimensional fake from a real knight. Magically controlled arrows are *expensive*. If a well equipped (with dummies) army can exhaust the supply of arrows, then the odds are even they might prevail in the conventional conflict that comes next. **Note:** Military engagements usually consist of a number of intersecting strategies all working in synergy. Consider all the answers and using their suggestions together or in sequence. [Answer] > > Would armor evolve in this context? > > > Possibly. Arrows would not be the only threat in a battlefield. When the arrows are over it's lancing time, and when the spears break you get down to swords and fisticuffs. However, armor might evolve to become lighter so as to allow you to clear the distance between you and an archer's neck more quickly. Or, since magic is involved, armor could be made that repels arrows. > > What defensive measures would an army take against such archers? > > > Golems. A five meters tall (that is about 4.1 laundry machines stacked up, in American units) mindless beast made of rock will barely be tickled by smart arrows. Also medieval-punk tanks, like [those invented by a real world artificer called called Leonardo](https://en.wikipedia.org/wiki/Leonardo%27s_fighting_vehicle). In reality we all know this was probably designed by Donatello, who was the nerdier turtle. Anyway the tank would have a canon that fires upwards, and no windows from which a magical arrow could enter. The canon ball would then fly to the target using the same magitechnology that propels arrows, with a wizard guiding it through a crystal ball inside the tank. [Answer] **Artillery** That is, arrows are used as artillery rounds instead of pinpointing enemies. Make a bomb, attach it to the smart arrow and launch it upwards like a mortar shell, possibly altering its course that a normal cannoneer couldn't, so that it would come down the ballistic trajectory on the enemy smart archers' heads. This can be launched from as far as the other side of the hill, depending on the propeller's physical power. Assuming 5 seconds of an 1G acceleration, it's already 50 m/s barrel speed, which is enough for about 180 meters (ballistics!), launch from a trebuchet THEN accelerate for greatly increased range and accuracy. It should blow up upon hitting the ground, wreck anyone close with good old shrapnel and also provide a good indication to the smart missile users on where to adjust aiming (over/underflight, left/right, that sort), so the next set of rounds would land closer or hit the enemy positions destroying their capability of using magic arrows vs your own infantry or knights. [Answer] A simple solution that would make it hard for your smart arrow users to see their targets properly would be polish. Lots and lots of polish! If the opposing army buffs up their armour to a high mirror shine, the reflecting light is going to make it very difficult to actually pinpoint where those arrows are going to land. For something along the lines of the magical technology in the arrows, have armour that has magitech built in that strengthens joints to stop arrow penetration. This would have the added benefit of making it more resistant to other weapons as well. I'm not sure how advanced the magitech is in the world, but eyeless helmets could be a thing with magitech viewing panels on the inside of the helmet, similar to a reinforced glass visor [Answer] ## Partial answer: Tennis rackets With eye slits being expertly covered by other answers (dazzle patterns), this answer deals with arrows navigating around other defensive measures like shields, or targeting weakspots. To turn and aim towards a targeted weakspot I strongly suspect that the arrow has to temporarily slow down in mid air. That would be the ideal moment to intercept the arrow and to swat it down. However to achive the neccessary precision and speed with a sword or other "normal" weapon would be difficult. Over some iterations some craftsmen would produce the ideal tool for this task, it has to be light (so you can swing fast), have a big surface area (to reduce the neccessary accuarcy) and have little air resistance (again to be swung fast and acccurate). The anwser is a net of strings attached to a wooden frame and a short to medium length grip: a tennis racket. While under fire of smart arrows, a knight would use the racket to swat down arrows that aim for his joints. A good swat would probably not destroy the arrow, but get it off track long enough so the short control time runs out. As soon as he engages in close combat he would sheath his racket and take his weapon to take on his opponent. ## Devastating smart arrow tactics Like many pointed out, smart arrows en mass would probably be outperformed by simply more normal arrow volleys (due to higher fire rate of normal arrows). However I think smart arrows could make for some devastating volley attacks with minimal control time of the arrows. As soon as the enemy is a bit closer than the maximu range of your arrows, you tell your archers to overshoot and let the arrows turn into their backs right before they hit the ground. Or same but shooting to either side of the enemies. Arrow volleys from the side or behind are especially dangerous and demoralizing. The only counter would be armors that are the same thickness all around in contrast to real medieval armors that concentrated on the front. This would greatly increase the weight and cost of the armor, reducing the number of knights the enemy can deploy and also wearing them out much faster. [Answer] Simplest is a plain armor with a "burka-like" overcoat preventing "smart archers" from seeing where weak points are. A bit of padding would even prevent guessing where eye-slits are. [Answer] ## Active Defense Some modern tanks use explosive charges on the exterior of their armor to interfere with penetrating rounds. The incoming projectile needs to explode at just the right time to inject a stream of superheated liquid metal into the tank. So they try to blow it up early and disrupt the attack. So a counter-arrow arrow or mini-fireball spell is attached to the knights' shields. This spell detects the incoming rounds, and fires off the countermeasure, disrupting the smart-arrow at the most crucial moment when the archer is controlling it. A knight might carry several of these pre-made counter-spells in a bag, and "re-load" the active defense after it triggers - you probably don't want multiple mini-fireballs attached to the shield at one time. This does mean there is a period of lowered defense while the knight re-sets her countermeasures. They remain susceptible to a saturation attack. [Answer] Here is a frame challenge, your arrows will rarely be used in the battle field. Thus armor will not change much, maybe apart from getting thicker to protect from faster projectiles. It will be immensely useful for assassins but not army archers. Controlling the arrow will be waste of time as precision is rarely necessary in battlefield. You don't target an individual, you target the group. Normally, by the time the first arrow lands, the archer would be releasing the next arrow (12 arrows/minute is a common firing speed). You will practically halve your attack speed. Your aim in battle is to not to hit a soldier, but to leave no place for a soldier to survive. While extreme precision could help preserve ammo, I am not certain how well it will improve the end result. For one, you will sometimes lose track of your arrow among so many. Also, you will not be able to react with speed of the arrow to target very narrow openings even with extensive training unless you see from the point of view of the arrow which is not compatible with your archer has to see the arrow rule. At the distances you could see, a good archer will be able to hit an eye slit with pin point accuracy anyway. Maybe novice archers will benefit from precision in closer distances. I think the most useful part of your arrow in battlefield would be the added damage. But your arrows would be god sent for adventurers and assassins. But I am guessing you already know that. [Answer] While I quite like Demigan's proposal to use dazzle patterns, I'd like to add on to it: ## Ghillie Suits Unless they're using some sort of telescopic sights, archers can't *actually* see someone's eye slits at longer ranges. The Mark I EyeballTM has limits. Insofar as they *do* (sometimes) snipe eye slits and joints at range, it is because they know where they are. Practice does, after all, make perfect. Thankfully for the officer corps, there are a few different ways you can counter this. First off, as Demigan mentioned, you can use dazzle-pattern camouflage. He already explained how it works, so I feel no need to expound upon it further. Second, you could use ghillie suits. These break up the wearer's outline, making it *much* harder to identify small features. Combined, I imagine that these methods would make it almost impossible to accurately identify and track such a small target as an eye slit or armpit. Plus, who *doesn't* want to run around the battlefield looking like they'd just come from a Carnival or Mardi Gras parade? [Answer] ## Anti-arrow arrows The way to stop these smart arrows is smart defenses. Perhaps not an arrow, perhaps a shifting piece of armor, but it moves to intercept the attacking arrow and knock it out of the sky. Possibly something that the arrow will embed itself in, thus using up its five seconds trying to get out if it gets that smart. ]
[Question] [ Basically, I want to decisively put an end to any idea that lasers could be used in my space combat in any large degree. One of the solutions I've thought of is a world having advanced armour (either through a coating or something else) that is resistant enough to lasers (or I guess heat because that is what the damage comes from if I am correct) to the point where they are basically useless in combat or at the least are very niche (like maybe you could still use them for taking out enemy sensors at long range). I was wondering if having this be something people could do would imply some other things they should be able to do scientifically that would have important ramifications on the world and whether or not they would still have to deal with getting rid of waste heat from being attacked by a laser even if the direct damage was countered. [Answer] "I want to decisively put an end to any idea that lasers could be used in my space combat in any large degree" You could do that going the *opposite* way. You could say that *ablative armor* is cheap, can be replaced/replenished by simply landing on any old chunk of space ice or dead comet, melting some volatiles and painting them on a spaceship before letting them re-freeze, and when hit by a laser this "armor" vaporizes locally, creating a cloud that immediately intercepts and disperses most of the energy of the laser hit ("[thermal blooming](https://books.google.it/books?id=ksDsDAAAQBAJ&pg=PA381&redir_esc=y#v=onepage&q&f=false)"). The only way a laser can get through this kind of "armor" would be by *repeatedly hitting the exact same point*, which, given a small rotation by the victim and a negligible bit of impredictability in its manoeuvers, is **impossible** in practice at any reasonable range. So, lasers are out because they're mostly harmless. You still keep them aboard - them and slug-throwers - to deflect space debris and rubble, and maybe repel boarders, but using lasers as *anti-ship weapons* is a ludicrous idea. You can have *laser heads* - missiles with fusion [bomb-pumped lasers](https://en.wikipedia.org/wiki/Project_Excalibur) - but those aren't properly *lasers* - they're missiles that just need to get *near enough*. # if we had but power enough, and time Super-duper fusion reactors come with issues of their own: **efficiency**. You would need to dump a frightful amount of waste heat, making the attacking ship large, clumsy and *fragile*. Static bases on ice worlds, capable of dumping heat underground, might equip monstrous pulsed lasers. Ships, not so much. Pulsed lasers are more feasible in an atmosphere and a gravity field, because both concur to disperse the vaporized material. In vacuum and microgravity, you'd get a cloud of ablated material all around the targeted ship, and the cloud would quickly dissipate most of the incoming energy. Using missile heads, you can hit from multiple directions and maximize initial kinetic transfer, getting more literal bang for your buck. [Answer] ## Frame Challenge: Lasers are a no-go because laserboats are flying radiators Just bring in proper heat management to your universe, and earn the realism points that even The Expanse didn't. Modern multi-megawatt CO2 lasers barely scratch 15-20% in efficiency (output power / pump power). That means, for every terawatt beam you've got to dump four more terawatts of waste heat. This is *besides* your power plant's inefficiency; if it's 50% efficient, you're looking at *ten* TW to dump. And that in turn is before any combat redundancy in radiators, which you do want to have. The only way to dump heat in vacuum is radiation, as opposed to conduction and convection you're used to in Earth's atmosphere. The only way you can radiate heat is bringing something on your ship red-hot at least. Radiators on a laserboat have to be huge (or so hot it starts melting) to dump that much heat. And they can't be armored with anything other than wet paper, or they can't radiate. And by "huge" I mean "several times bigger than the rest of the ship". Basically, a terawatt laserboat is the ultimate glass cannon. Your navy may build and fly one, but it is so easily countered with missile spam cutting up the giant fins that nobody really bothers. (They *can* be cool mining or research vessels, though.) P.S. In case it gets moved to chat: nuke-pumped lasers are hard-countered with nuclear-tipped anti-missiles deliberately inducing a [nuclear fizzle](https://en.wikipedia.org/wiki/Fizzle_(nuclear_explosion)), a technique known as nuclear dudding. LIM-49 *Spartan* and 51T6 *Gorgon* ABMs are good examples; disabling warheads even when missing them by a kilometre. [Answer] [This blog post from ToughSF](https://toughsf.blogspot.com/2018/05/lasers-mirrors-and-star-pyramids.html) is a great read on defending spacecraft from laser warfare, with a specific focus on mirror armor, which I will be mostly basing my answer on. In short, there's no perfect defense against lasers. Any mirror will only be 99.999% effective (realistically less than that, but still), and in a relatively narrow range of wavelengths, and that 0.001% of beam energy absorbed will heat and degrade the mirror material until it's no longer effective and is promptly blasted away. However, in a scenario where lasers dominate, armor can be effective in closing the distances between opposing ships, from millions down to several thousand km, forcing them to slug it out with missiles and kinetics. Good for narrative purposes. The catch is that most if not all of the ship's systems are devoted to shrugging off laser fire. --- Realistic space lasers are pulsed, rather than continuous fire. Millions of high-energy pulses spaced microseconds apart. When a beam pulse strikes and heats the surface to a high enough temperature, the surface material flashes into a gas and rapidly expands, so fast that it causes mechanical stress in the material helping to weaken it. In the microsecond gap between pulses, the flashed material explodes and clears before the next pulse. [![pulse laser graph](https://i.stack.imgur.com/ZYqXz.gif)](https://i.stack.imgur.com/ZYqXz.gif) Optimal pulse lengths depend on the armor material used by the opponent, as different materials have different mechanical attributes, like ways of cracking and melting. The best armor material is one that takes the most energy to heat up and the most energy to destroy. High heat capacity and high melting/vaporization energy. It also should have a high tensile strength to fight the mechanical strain of microsecond pulse train lasers. Ideally, it'd also be lightweight and reflective. Graphite comes close as a candidate, with high heat capacity (0.72kJ/kg/K) and an extreme vaporization energy (59.5MJ/kg at 4000K), but has poor mechanical strength (30MPa). It is also not very reflective. --- Hot materials will radiate blackbody radiation. Energy radiated scales with the fourth power of temperature, meaning the hotter something can get the more energy it is able to shrug off. For high-performance armor, the radiation should be comparable to the laser intensity. When blackbody radiation is equal to laser intensity the laser does no damage, merely heating up the armor. This happens at great distances where the beam intensity is lower. Graphite vaporizes at 4000K and can dissipate up to 14.5MW/m^2. It can withstand the beam of a 10MW laser from a distance of 8500km — no damage is incurred beyond that point. That's already within reasonable missile range. Active cooling to pull heat away from the armor can reduce that distance even further. --- Sloping the armor in the direction of the beam can steepen the angle of incidence, spreading the beam intensity over a greater area, the spot elongating from a circle to an oval. At an angle of 80 degrees, beam intensity on the armor is reduced by 83%. This suggests that sharp cones are great at reducing laser effectiveness. Polygonal shapes such as pyramids with triangular, square, hexagonal or other bases could be more effective than a rounded cone by creating a compound angle (vertical and horizontal sloping) against the laser. [![star 1](https://i.stack.imgur.com/fOZTKm.png)](https://i.stack.imgur.com/fOZTKm.png) [![star 2](https://i.stack.imgur.com/RWk5pm.png)](https://i.stack.imgur.com/RWk5pm.png) *Star pyramid. 80 deg vertical slope, 67.5 deg horizontal slope.* Under extreme angles of sloping, [Fresnel reflection](https://www.rp-photonics.com/fresnel_equations.html) becomes significant, and more of the beam energy is dissipated. Graphite has a refractive index n = 1.5179 in 450nm light. That index, along with the slope angle, [can be used to calculate](https://www.pveducation.org/calculators/fresnel-reflection) how much of the laser's energy is reflected away. An extreme compounded slope such as the one produced by the star pyramid above would allow for nearly 70% of the laser energy to bounce off harmlessly. The graphite octogram star pyramid above would survive the 10MW laser at a distance of 2000km. [Answer] **It might work...** There are advanced insulating materials today that are fantastic at rejecting heat. But lasers aren't just beams of heat. They're beams of light — and that means you need to deal with *photons,* not just heat. *Reflection* A [perfectly mirrored surface](https://en.wikipedia.org/wiki/Perfect_mirror) would work, but at the energy levels needed for space combat, "perfect" would have to be remarkably close to "perfect." Every photon not reflected is left to wreak havoc with your ship. That previous link states that a very good dielectric mirror can reflect 99.999% of a narrow range of wavelengths, which might not prove useful in combat (build a laser outside the range of wavelengths...). Note, though, that at 99.999% reflection there's still 0.001% of energy dumped into your ship. 0.001% of a terrawatt laser (perhaps the bare minimum for space combat) is still 10 megawatts of energy. *My thanks to @ZizyArcher for catching my math error. He's correct, in terms of space battles one would think that 10MW isn't very much. A ship might encounter that simply passing within a normal distance from a star. That lends a lot of credence to the mirror method.* *Disruption* Another solution is something akin to the way flares are used to distract incoming missiles. Your ship squirts out a heavy mist of something oily or dusty that reflects, absorbs, and otherwise disrupts the incoming beam. This can consume most (if not all) of the energy before it hits your ship. *The only problem with this solution is that information cannot travel faster than the speed of light. In other words, if you can detect the fact that a laser has been fired, then you have already been hit by the beam. Thus, this solution would have to be constantly active during combat, which might make it impractical to use.* @BMF (*thank you!*) brings up a couple of more problems with this solution that are worth noting. * If you can see through the dust, the laser can get through it. That means the dust needs to be whomping thick, and that means all your sensors were just thrown to the dusty/oily wind. * Lasers, while impractical (see my alternative, below), have one advantage: they can be *pulsed.* This means the first pulse burns through the disruption, then the next gets through. Or you just keep pulsing (if you have the energy) and eventually you get through. Frankly, most armor will have this weakness. (See [this](https://www.galacticlibrary.net/wiki/Atmospheric_Hole_Burning) and [this from Worldbuilding.se](https://worldbuilding.stackexchange.com/q/238453/40609).) *Ablation* Ablative armor, in the case of lasers, is armor that vaporizes from the heat the laser delivers. Basically, armor becomes a consumable that must be replaced after each round of combat. The problem with ablation or any other dissipate-the-heat solution is that you need to account for photons, not just heat. The impact of a photon is a bigger deal than simple thermal resistance. An example is that an emergency blanket (one of those that fit in your pocket and look kinda silvery) will thermally insulate, *but when exposed long enough to sunlight, aka "photons," it becomes brittle and eventually cracks.* *Absorption* Another possibility is that you build your ship out of the most thermally conductive material you can find, then make sure you have something akin to a futuristic-almost-magical [thermoelectric generator](https://en.wikipedia.org/wiki/Thermoelectric_generator) that's taking all that heat and converting it into (hopefully) useful energy that can be applied to the imminent destruction of your enemies! This has some cons, not the least of which is that a thermally conductive material is a fuse by any other name. If your opponent beings a big enough laser to the fight, the hull of your ship will vaporize like so much [flash paper](https://www.vanishingincmagic.com/flash-paper/). **But maybe you should think about making lasers impractical to use.** I'm going to give you an idea that I've been saving for myself for my Great American Novel that, honestly, I'll likely never have time to write. It's not the greatest idea in the world, but I liked it enough to hold onto it for a fair number of years. Hopefully it either works for you or gives someone else inspiration to come up with an idea that will. Lasers take a LOT of *instantaneous power.* Power isn't free, and it isn't simply floating around waiting to be used. Power must be generated. That means if you're going to throw a dozen petajoules at your enemy, those joules must either... (a) be constantly available via an engine or power planet that's constantly generating tons more power than the ship ever needs save at the moment the laser is fired or... *@jpa points out that it's plausible for such a power plant to produce a significant and detectable magnetic field, thereby making the ship more detectable even before it can get a shot off. While shielding an electromagnetic signature is possible (see [Faraday Cages](https://en.wikipedia.org/wiki/Faraday_cage)) such a solution kinda only works if the sink for the energy goes somewhere kinda enormous (like a planet) when compared to the source field strength and charge involved. Thus, I think what @jpa is pitching is a very good point.* (b) the energy is being stored in batteries waiting to be used. Those batteries can be discharged when not in combat to keep things safe, but during combat those batteries are only discharged immediately after a laser was fired. *@BenVoigt points out that my answer is ignoring the reality that generating a laser isn't a perfect process. The lower the efficiency of power consumption to generate and transmit the laser, the more the ship needs to handle the problem. Enough waste heat and you either can't effectively strike your target or you vaporize yourself in the effort of doing so. A ship that can handle the waste heat lights up the darkness of space like an infrared Christmas tree. Yet another reason why lasers are impractical to begin with, but I digress...* What that all means is that a laser-firing ship is a disastrous explosion waiting to happen! Either the ship is over-powered (from a power plant perspective) or has a bunch of barely stable batteries just waiting to be hit. Once hit, the result is always catastrophic! I.E., why on earth would *anybody* use a laser-firing ship? Why would anyone want to serve on one? It's a death sentence. Worse, whatever you do to make a laser-firing ship more safe, *also makes the ship less efficient in combat.* In other words, you don't need to make lasers worthless because of advanced armor. They're pretty easy to justify as worthless all by themselves. After all, who other than [Slim Pickens](https://www.authorsden.com/visit/viewarticle.asp?id=81189) wants to sit on a barely contained explosion? *@Zovits points out that today's astronauts gladly sit on a barely contained explosion and the line of applicants is very long, so Slim's not alone. I chuckled with this entirely correct observation, but I suspect that given the choice of not sitting on a barely contained explosion would be taken by all of them — if it existed. Today it doesn't, but in the OP's world it does so long as lasers aren't involved.* [Answer] **Retro reflective shielding** While using a smooth polished reflective surface as shielding is one option, an alternative is to use reflective surface with a cubic pattern that will additionally reflect the light back where it came from. Not good if you want to avoid RADAR/LIDAR but if the reflection is accurate enough then you effectively turn your enemies weapons back onto them. Literally targeting their weapon ports. Though retro reflectors are often cubic prisms where the back surface actually reflects the light so weathering of the outer surface doesn't diminish it's effectiveness. Manufactured diamond could possibly work well in this role (though strong things tend to also be brittle so that could be a physical weakness). **Efficiency works both ways** A reflective surface that is able to reflect 99% of the light that hits it seems perfectly reasonable, but producing LASER light with this level of efficiency and also having a power source with this level of efficiency is likely a much bigger challenge. If you can't produce a LASER weapon and power supply that has comparable efficiency to what is possible in shields you end up dealing with more heat than your opponent. [Answer] # Heat radiation Heat is probably the worst thing you can have in space. The reason is simple. There are precious few ways to get rid of it. As you're basically going through a vacuum there is too little to take up the heat. You need to radiate it away. This is a slow process. Look at the International Space Station. It actually has a *lot* of plates to radiate heat away from the station. Take this to the space battle. To fire a tera watt laser, you also produce tons of heat to fire it. If the opponent can reflect part of the beam you are in danger of receiving more heat than your opposition. If you're not careful, things overheat. From life support to batteries to the organisms inside. It can be safer to just fire rockets and the like. Things that take (part of the) heat with them. A laser can still be useful, but only in very niche situations. [Answer] Frame challenge: Lasers as a primary armament are difficult, if not impossible, to justify using. Heat management, energy requirements, EMR signature, weapon dispersion with distance, and targeting (both because of target ablation, and material properties of the target) all make it incredibly difficult to do serious damage to even a lightly armored target. Kinetic weapons, while limited on ammunition, are much cheaper and much more space efficient, and can be "rearmed" at any source of material, given an ammunition forge that you feed raw material into. Missiles (which I will refer to as chemical or thermal weapons) pack a much bigger punch for each shot, and tend to end conflicts much faster. Lasers, while nearly useless as a primary armament, do serve one critical purpose though. When an OpFor vessel is unarmored, or has had its armor stripped from it through combat, a focused pulse laser at close range can cheaply and quickly/precisely cripple or destroy the target, without having to waste ammunition or risk missing the target (or risk damaging something on the target you wish to retrieve intact). They also serve as both CIWS/Anti-missle defenses, and as a last line weapon for when your ammunition reserves deplete, allowing you to still defend yourself on the regroup or retreat. [Answer] The way you make any weapon useless is to make them too costly to use. Cost in battle can include many things, but here's an idea that would make it extremely difficult to justify firing a laser at a space ship: photoelectric conversion. One of the major issues with space ships is the mass of the generators required to power them. We solve this problem in a variety of ways today, but just about everything we put in space (inside the orbit of Jupiter at least) uses photovoltaic cells to provide at least some of the power requirements. With current material science we are starting to produce photoelectric metamaterials that are significantly more efficient at turning photons into electron flow, with the goal of drastically improving the power output of solar panels. Since this is a science *fiction* question, we can take it a whole lot further. Imagine a material that converts photons across a reasonable range of frequencies to electricity at extremely high efficiency. Armor plates covered in this material would do double duty as solar panels to provide supplementary power, but where they'd really shine (or whatever the *exact opposite* of that is) is when someone is dumb enough to point a laser at you. All those lovely megawatts of laser power flowing into your power grid would be a real boon in the energy-expensive battle environment. Pump it through to your weapons array and let your enemy have his energy back as kinetic or plasma fire. About five minutes after that becomes a reality every ship would tear out their primary laser batteries and replace them with literally anything else. Laser point defense would still have a place of course, but nobody's ever going to point a large laser at a black ship ever again. Well, nobody with a brain. The minor inefficiencies are of course going to produce heat and probably degradation of the material. We can solve the heat issue by using some of the absorbed power to run our heat management systems and use multiple layers of ablative armor panels to prolong the longevity of the protection, laminated with other materials to provide kinetic and plasma protection. Maybe dump all that heat into sodium tanks and fire those at your enemies, like napalm. Et voila, no more lasers in combat. Well, not offensively anyway. With this kind of armor on the field we can do something much more fun with lasers: support laser platforms! Big, slow ships built around massive power plants whose role in combat is to stand clear of the fight and pump power into friendly ships by shooting them with lasers. Your ships could then carry much smaller power plants but still pack a massive punch because their power is externally derived. Imagine a corvette-class ship that maneuvers like a frigate but hits like a destroyer... as long as the support platform is sending power. Or how about swarms of little ships that are individually pretty weak and take a long time to fire their main cannons, but are able to share power with each other. The could focus power down to an individual ship, let it fire a big shot, then move the power to the next ship that's ready and in position to fire. Maybe it blows the firing ship up, but they're a lot cheaper to build than destroyers. (It'd be a real shame if someone sold this stuff to that hive species you've been fighting, wouldn't it.) If you want to get really silly though (as if we weren't already there), how about dropping a ship into the photosphere of the local sun and using the abundant energy to power magnetic fields that channel solar plasma into tightly controlled beams. For mining purposes, obviously. Definitely not a weapon that could glass a planet in the habitable zone. Absolutely not designed to create coronal mass ejections on demand. What kind of lunatic do you take me for? --- And yes, there's a simple solution to this: dirty solar panels don't generate power as efficiently. If you open combat with a volley of paint or mud or something to foul the armor you can hit them with lasers again. That'll probably surprise the heck out of someone the first time you do it. [Answer] Frame Challenge: I'm going to cite Dune here as a good method of making *insert Weaponary* unusable. In Dune - people have personal energy shields, these sheilds when hit by 'directed energy weapons' can potentially cause an explosion equivalent to a Nuclear blast (Atomics in the universe) - or it could simply kill the target *and* the attacker. Additionally, the use of Atomics by the great houses is strictly forbidden and should one house use it against another, the other houses would annihilate the aggressor house. Because of this, a sort of MAD or Mutually Assured Destruction stalemate occurs. In short: Anyone who is 'worth' killing is likely to be wearing a Shield and using a laser against a shielded target could result in a Nuclear explosion and a Nuclear explosion would result in everyone getting destroyed: *No one uses Lasers for fear of triggering this* So - to answer your question in a different way - you could make it so that the common method of protecting oneself in Space (a Necessity) would cause catastrophic damage to both parties if one of them attempted to use Lasers - therefore no one does. [Answer] **Thrust by ablation.** There are two types of laser shield (without going into force-field-shields and other things Star Trek); reflective shields and ablative ones. We've recently had several [questions regarding reflective ones](https://worldbuilding.stackexchange.com/questions/166611/ideal-materials-for-laser-energy-weapon-defense), all have answers about how useless they are. Ablation however, is the heating and evaporation of material from the heat shield. Something like graphite or other material absorbing lots of energy when it evaporates. In principle it's great, absorbs several shots, cheep and can be easily replaceable by droids after a fight. The disadvantage is that if you're in a nice tight formation, all with ablative nose-ends facing the enemy - they can hit you off-centre and this will create [thrust by plasma-plume](https://en.wikipedia.org/wiki/Laser_propulsion#Ablative_laser_propulsion), just like they're turning on a rocket-engine forcing your nose over and changing your vector. It's a bit mean of them, but aimed accurately, they can smash your ships into each-other before you even get into the fight. [Answer] You can't put an end to using lasers except if you handwave it to a large degree. The thing is that current Earth-based pulsed lasers are already powerful enough to be useful to blast missiles out of the sky, and this is an active area of research to make it actually work in practice. I believe we will get there in a decade or so. You can't even invent "huge explosion mostly stopped all this research blahblah", there are far too many lasers used in far too many settings - unless someone external prohibits/prevents lasers, research will likely keep going on. Yeah, your large lasers might keep exploding because of handwavium, but smaller lasers are known to already work reasonably well and a bunch of them would be good enough to blast a missile out of the sky with great aiming. So, lasers for point defense against missiles flying long range? You can count on it. I believe it will lead to laser side dominating eventually, making missiles unplausible for long-range space combat. Now, for ship defenses preventing lasers from attacking same size ships. Side firing beam would have huge mirrors and focus on a much smaller spot on the target ship. Firing side can be optimized for a single wavelength (possibly several or even tunable), receiving side must accept anything as you can't know what the attacker will use. CW laser: Top side would likely be dielectric mirror tuned for the expected wavelength range that doesn't absorb but lets some light through. Underneath you would have a metallic mirror on a high aspect ratio structure. This greatly increases effective area and lets the structure survive. This passive defense is likely good enough that CW lasers are useless against ships in the same class and possibly one lower ... but a larger ship will be able to smash smaller one, including missiles. Pulsed laser: Dielectric mirror starts absorbing unhealthy amount and the high aspect ratio is beneficial just for the first shot and gone afterward. The only realistic defense is ablative armor. It doesn't work quite as good against CW with higher average power, but you can use (in)efficiency argument and old passive armor as why ships wouldn't use it much. Here, the moment you see someone, you can deploy anti-laser magnetic particles (chunks of iron) flying around the ship on predictable trajectories way out of the ship, with some brief holes around windows and guns every now and then so you see what is going on and fire at the target. Enemy projectile weapons smash right through your "shield", but a lot of laser gets absorbed vaporizing that iron. With iron being cheap enough you can make this pretty effective for ships in the same class. Again, smaller ships couldn't really survive hits from larger ones... but that's pretty much par for the course with most weapons. ]
[Question] [ Our intrepid wizard protagonist realizes there is only one of him and an army of baddies. He has a band of some 50 people with him, but only a dozen have combat training and he is the only spellcaster. The guards are working on tactics, wooden spikes, choke points, and [etc](https://c.tenor.com/1i0_NMO7MLUAAAAC/war-badass.gif). Our wizard wants to make weapons to help. Deciding the best chance of survival lies in keeping enemies at a distance, our wizard looks for how to do that while also overcoming the numerical odds against them. Knowing he doesn't have enough [spell slots](https://ksr-ugc.imgix.net/assets/030/181/943/acd58b4137135312fdcf747e9d7a83a0_original.gif?ixlib=rb-4.0.2&w=680&fit=max&v=1597321515&auto=format&gif-q=50&q=92&s=136f23a08ff6c6f472ec094d16185f37)/[mana](https://static.wikia.nocookie.net/diablo/images/9/91/Mana_orb.gif/revision/latest/scale-to-width-down/107?cb=20150904143428)/[mojo](https://media0.giphy.com/media/nfKdTuhshHG7K/giphy.gif?cid=790b76119263b800b68c83f243d763703d07b799c33a7d2e&rid=giphy.gif&ct=g) to fire the requisite number of fireballs and something like arrows won't be enough to offset the numbers, he settles on grenades. His magic grenades use runes to hold magic. When the runes are damaged, the magic stored within explodes. This means his grenades need to break (or preferably shatter) on impact. He and his band are in a mountain forest with no cities available. He has three months to stockpile grenades, knowing that when the winter ends, his enemies will be upon him. He has access to metal tools, brick, stone, wood, animals, snow, and everything else you would expect in a mountain forest with medieval technology. Some magic to aid in production, but no [alchemy](https://cdn.myanimelist.net/s/common/uploaded_files/1441222828-2739936bc6d2bacb48c2a1926f47181b.gif) or other [easy solutions](https://static.wikia.nocookie.net/terran-federation/images/3/33/DarlingImaginativeHammerkop-size_restricted.gif/revision/latest?cb=20200917212315). **What real-world material can he use which can be both thrown easily (like grenades) and will shatter, or at least break, on impact?** Is there a type of stone that fits the bill? Is slate brittle enough, for example? Can the brittle stone be shaped into a sphere for easier throwing? Can hollow bricks be made for this purpose? Is there a form of primitive glass he could make, or another material that would work? [Answer] Egg shells if the wizard wants to go for naturally available materials, or pottery balls if they can go for manufactured materials. Both are conveniently empty and can be filled with whatever needed, and the filling hole can be sealed with clay/wax. Moreover both easily crack on impact, assuring that the wizard can achieve the intended result. [Answer] > > ...knowing that when the winter ends, his enemies will be upon him > > > It's going to be winter until the enemy arrives? Use **ice**. He surely has water around, and freezing things is within a wizard's capabilities. [Answer] If your wizard can make bricks, he can make hollow ceramic bulbs. Bricks are made from baked or fired clay. Via the same process, you can make a vessel of the right thickness to hold when thrown, but shatter upon impact. You could for instance wrap clay around a pine cone or plant bulb or rounded chunk of wood, then fire it in a kiln. [Answer] **Snow.** [![snowball](https://i.stack.imgur.com/cErIz.jpg)](https://i.stack.imgur.com/cErIz.jpg) <https://www.youtube.com/watch?v=T5XutpETUkM> It is on your list! And it shatters great. Have your peeps dig a snowball cellar in case you have some hot days before the baddies come. Then load it up with snowballs. You can incorporate some yellow snow, to add insult to injury. Ice grenades would also do the trick. [Answer] ## Unfired Clay When making ceramics, you first form your object out of clay, wait for it to dry for about a week (give or take a few days depending on humidity), then you bake it in a kiln for anywhere from several hours to several days to make the clay melt together into the glass like substance we generally call ceramics. While ceramics have been brought up already, greenware (or fully dried but unfired ceramics) are both more brittle and much easier to mass produce. The final step of making ceramics uses up a lot of fuel. Even a small kiln only meant for a single jug or pot can take up about 2 cubic meters of fire wood to properly fire, plus they require constant vigilance during the firing process... but since you want brittle objects anyway, you can skip this part. An unskilled laborer could manage the entire production process from gathering local resources to a finished product well enough to make dozens, if not hundreds of these things a day. The way you would make them is to start off by clearing some dry ground, preferably somewhere sandy or loamy. Then you mix your clay which is just the right kind of dirt plus water, or better yet, you use the naturally ready to use clays like you often find in riverbanks. You then lay a sheet of clay and flatten it like cookie dough. Then using a fired ceramic mold designed by the wizard in the shape of your rune, you stamp a repeating pattern into the sheet (also like cookie dough), then using a knife or even a mildly sharpened stick, you finish off any cuts that were not fully made by the "cookie cutter". The you just leave them there on the ground to dry in the sun. After about 1-2 days, the tablets will be dry enough to handle. Since you caste them on sand, you don't have to worry about them sticking to the surface, they will just lift up with the sand they stuck to no problem. At this point you just bring them inside where they can finish drying and be stored, and you can use your clearing again to lay down the next batch. Over the next few days, some of them will crack while they finish drying; so, you want to wait the full 7 days before casting any enchantments on them or else they might spontaneously explode. ## Why this is better than other solutions It is way cheaper; so, you can make a lot more of them. Not only are you saving a lot of time and fuel not firing it, but you are also simplifying the shape. Because greenware breaks more easily that fired clay, you don't need to make it hallow or really thin to make sure it will shatter on impact. Even eggs are more expensive because of the time, food, and land space required to raise chickens. Snow is probably the only cheaper material listed so far, but snow crumbles in your hand too easily, and even a little bit of seasonal warming will likely cause one of your snowballs in storage to come apparat and blow up your whole cache. The big downside is that care must be taken to keep them dry, if your weapon cache floods, you will have a big problem, but the same is also true of other historical weapons like bows or iron weapons; so, maintaining a dry armory is already a priority and available skill set at the time. ## Also, you can supplement this idea with land-mines! As the enemy army marches, the dirt under their feet naturally breaks apart as it is flattened. So, as the enemy army gets close, your wizard can go out to the main road with a bucket of water, wet the dirt if need be, and then stamp the rune into it. He then casts his enchantment directly on the ground and covers it wit dead leaves or what not so when an enemy solider steps in the mud, it breaks the rune. [Answer] Slate plates. Explosions are nice... but a lot of additional damage can be done also by shards of the projectile itself. So you want something, that shatters into many sharp pieces. When you say "grenade", the first idea is to have it ball-shaped... but runes are usually painted on a surface. If the rune releases its power on the surface, it will throw all fragments to one side. With a ball you have no control over which side that is, and half of the time it will be towards the ground (i.e. not hitting anyone). Since you are already using magic here, you could of course use a more advanced spell to make the projectile magically explode from its precise center. However, you are making many of these grenades... so I guess you want to keep the spell as simple as possible. A plate thrown like a frisbee will keep its orientation. Paint a simple explosion rune on its bottom side, and you are guaranteed to have all shards flying around. [Answer] An alternative answer: very high carbon steel. All of the other answers posted answer your question well, but a bit out-of-the box might be what you're looking for. Forge arrowheads (you said metal, tools, wood?). Make a kiln/furnace and case harden your arrowheads as much as possible (increasing the carbon concentration in iron makes it harder, but more brittle). Make them thin-walled and hollow, with an opening in the rear to plug with an arrowshaft. Fill the arrowhead with "magic", preferably one that does "contagious" damage. The arrowhead will break when it hits a bone, and immediately release the magic (exploding enemies? sounds like fun). Bonus: your arrowheads will be *exceptionally* sharp if they're file-hard and you can stone an edge onto them. [Answer] **How Low Can You Go?** * Wax - from bee hives * Resin - from evergreen trees * Feces - from bears, etcetera * latex - from trees, dandelions etcetera * galls - plant "tumors" grown around insect larva * gourds - or other hollow shelled fruit * animal intestines and bladders Some combination of the first four ingredients mixed with fibers from plants, animal hair, etcetera to adjust their durability for transport. The options for disgusting humor abound! [Answer] It's unclear if the rune is an object in its own right held in a delivery device, or merely a symbol on some other object. I'm going to assume the latter, as that seems to more closely match your description. Thus, assuming you can draw/paint/apply a rune to some existing object which needs to break when thrown... * Eggs. Can be produced in rather large quantities readily. *DON'T* empty them first; the extra mass will help them have enough inertia to break on impact. * Some rocks should be sufficiently brittle; flint, slate, chalk, maybe sandstone. * Thin-walled ceramics definitely should work. You can probably get away with making [disks](https://en.wikipedia.org/wiki/Clay_pigeon_shooting) and throwing them as such, though this may require more skill than lobbing something more spherical. You might not even need to fire them; balls of mud dried in a fire might work. * [Polished turds](https://en.wikipedia.org/wiki/Dorodango)? üòâ (Or you could use dirt. I'm not sure how well these hold up under normal handling, though, or if they'll break like you want.) * I'd suggest rotten wood, but might be hard to apply the runes, and probably is too likely to break when merely handled. * Snow has similar problems as rotten wood. * Balls of ice *might* work, but keeping them from melting will be difficult. If the rune is applied to the surface, melting is going to tend to mess it up, making these possibly more dangerous to *you* than to an enemy. (Can you *also* add a rune to stop it melting?) * If you're *really* in a pinch, throwing a heavy branch (you'll want it to tumble end over end, like a boomerang) hard enough might break it, but this may be unreliable, and you don't want the enemy hurling it back at you if it doesn't break on the first try. * If you have access to some sort of cement, you can make plaster or concrete. As with pottery, you want to make something thin so it will break easily. Personally, I think eggs are your best bet. Easy to produce, and fairly consistent, which should help with troops being able to throw them accurately. Also, their surface definitely won't wear readily, which is important if runes getting smudged causes them to "go off". Some sort of dried (possibly fired) mud/clay *molded* into balls might be your second best bet. [Answer] I'm not sure how practical this would be, but any riff on this theme would be pretty cool. [**Prince Rupert's Drops**](https://en.wikipedia.org/wiki/Prince_Rupert%27s_drop) are created by dripping molten glass into cold water. The bulbous end is extremely strong, but if the tail is damaged the whole thing disintegrates explosively. You can find many [videos](https://www.youtube.com/watch?v=xe-f4gokRBs) demonstrating their interesting properties. I am not sure if they would be guaranteed to shatter when thrown but I suspect they would most of the time. [Answer] > > His magic grenades use runes to hold magic. When > the runes are damaged, the magic stored within > explodes. This means his grenades need to break > (or preferably shatter) on impact. > > > I don't think your last sentence is accurate, and it's limiting your design space. Grenades are quite sturdy and do not shatter from an impact. They shatter due to the force of the explosion. The lack of shattering is one of the things that makes them so deadly, because it allows the pressure inside to build up until it shreds the shell into a hundred shards and sends those shards flying at high speeds. A shattering grenade cannot build up pressure, so a lot of the explosive force ends up pressing on the ambient air (not helpful) and the deadly shrapnel ends up with much less kinetic energy. That means instead of looking for something that's brittle and will shatter, you want something that will contain the explosion long enough to build up a lot of pressure, but will eventually yield catastrophically. One easy to construct option is to build drawstring pouches out of [tincloth](https://www.instructables.com/Tincloth/) (canvas cloth boiled in beeswax). This will be less porous than regular cloth and let less air escape. Fill the bag with glass/pottery shards, ball bearings, or even large gravel, then place your explosive rune in the middle. When you throw it, the impact with the ground will cause the shrapnel to slam into the rune, damaging it enough to set it off. The bag will contain the explosion briefly, but eventually the shrapnel will tear through the bag and go flying in all directions. Think of it like magically-powered grapeshot. Another good option for natural materials are coconuts. The shells are strong, but will eventually shatter into irregular shards that can be quite sharp. Drill a small hole, place your rune inside, and seal it as tightly as you can. There's even lots of room inside to pack it with shrapnel. Pineapples could also be used, but would require more work to hollow out. One very nonconventional material would be to use bone. It's strong, and splintered bone can be very sharp. When your group hunts for food, save the skulls and dry them out (don't bleach them though). Place your explosive rune inside the skull, fill with shrapnel, and seal off all openings as well as you can. [Answer] If it's available, obsidian. Obsidian is glass, so it shatters into very sharp pieces. The downsides are that the pieces need to be large enough to shatter, and obsidian is rare unless the mountain is/was a volcano. [Answer] I'll agree with others that clay, either fired or just dried, is probably your best bet (presumably a small experiment to see which stood up best to storage and also shattered reliably on landing but not on throwing/hurling/whatever). Slates or sticks sawn to near-failure are probably also a good bet (especially if you start running out of clay). Sticks in particular would be devastating landmines as no one would expect a random stick in a forest (until they started suspecting every stick in the forest :) ) If there's a convenient choke point and the tech allows there might be something to be said for having some sort of seige weapon and a number of somewhat thicker flat plates (thicker and flatter so they could be stacked in the bucket/payload-holder. Might need some experimenting for feasibility first though...) Eggs are a great idea for summer but not likely to be produced in sufficient quantities (or perhaps at all) in the winter due to the temperature and lack of daylight. Given 6 months your wizard could potentially stockpile some eggs, if they aren't needed for food instead. [Answer] Could [Prince Rupert's Drops](https://en.wikipedia.org/wiki/Prince_Rupert%27s_drop) be useful? If you drip molten glass into water it forms tadpole-shaped drops. The internal stress within these drops makes them very strong: you can hit one with a hammer and it won't break. But if you break the tail it instantly shatters into powder. Put magic into these and have a simple mechanism which breaks the tail on impact, and you have your magic hand grenade. [Answer] As someone else pointed out, grenades normally explode (due to being full of explosive with a fuse or detonator and all that) rather than shattering. However some types of weapon rely on the container breaking and exposing the contents to the air, which seems similar to your use case. Improvised phosphorus bombs, for example. The container used is normally an empty beer bottle. [Answer] I don't think it's better than the other answers, but I'm adding it for completeness since it was my first thought: pumpkins! Not only do they shatter on impact, but they follow the Rule of Cool for magic. And if the starting time frame is end of fall, it's plausible that you have plenty on hand. [Answer] In reality, anything vitreous or ceramic might shatter when it hits something, but you might still need to specify what "like a grenade" means. Please remember, grenades do not "shatter" and are not interested in contact; they are exploded, from within, by timing mechanisms. To be really picky, that's why we generally speak of grenade "fragments", not "shards." Worldbuilding isn't reality so the rules and characteristics are up to the builder. ]
[Question] [ In this world there has been a recurring population surge of ferocious insects every 20 years for many centuries. The setting is approximately our own time in relation to the existence of "cave men". In other words, since around the time humans began to create things and have fire, essentially stone age technology, there has been a plague of insect attacks which very nearly destroy the population every 20 years. Consider the cicada: <https://en.wikipedia.org/wiki/Cicada> and the locust: <https://en.wikipedia.org/wiki/Locust> merging the two behavioral characteristics into a larger insect which feeds primarily on humans. Possibly feeding on other mammals as well, presumably due to the weakness of exposed skin and that they are warm blooded. How far could human civilization progress given this hindrance in individual development? If they were able to advance similarly, how would civilization be different? How might humans evolve over this time span? I am looking for answers which are realistic, but some creative leeway is allowed. No explicitly magical answers please. Points to keep in mind (derived from answers): * The insects have a life-cycle like a cicada and feed like locusts but on flesh. * The adult insect is slightly smaller than your head (not including wings). * Humans are a prime target but the insects feed on other warm blooded creatures * The eggs and larval stage exist in hidden and spread out locations, under ground or deep in caves. * The attacks are horrible and many people die, but there are enough survivors to keep the human population from going extinct. Edit: Not just any Cicada, specifically the Periodic Cicada: <https://en.wikipedia.org/wiki/Periodical_cicadas> [Answer] Presumably the insects swarm, gorge, breed, then either die or hibernate. Then come out in force 20 years later after the eggs have hatched and the larvae mature into adults who can fly and who need human blood in order to support breeding. Humans have 20 years to find and kill the eggs or to kill the larvae. If the eggs are grouped together, then fire is something even primitive peoples can handle. If the eggs are in clusters but the clusters are spread out, lots of kids with pointy sticks will do the trick. If they're very spread out or in inaccessible places, it's harder. This should reduce the population of killer insects enough that more humans survive. After a few generations, there are fewer eggs/larvae to kill and more humans to do it. **The pressures to do this more efficiently will help drive technology, communication, education, and more.** All the things in other answers will come into play: * Better housing (or at least strong shelters with a water source and food storage to last a few days or weeks) * Protective clothing * Food preservation * Calendars * Methods to predict the swarms * Surveillance techniques to know when the swarms have gone * Containers to store food and water * Indoor cooking methods * Light sources * Ventilation methods * Understanding geology and movement of water including underground sources * Well building **Differences with a real-life society?** * Their religion will probably be on 20 year cycles and be focused on the plague. * They will be obsessed with calendars and weather prediction. * Material science and engineering will be advanced. * Exploration will be a high priority (finding a region the bugs can't get them). [Answer] **No advancement at all** Let's assume "very nearly destroyed" (a very vague description) means less than 5% of the population survives every attack. Those attacks occur every 20 years. Let's make an *outrageous* assumption that the only remaining people are distributed 19:1 in favor of women and all the women are prime childbearing (18-20 years old). In [10,000 BCE the world population is estimated to be 2.4 million](https://ourworldindata.org/world-population-growth). The late stone age was about 40,000 BCE, let's assume 1 million people. The insects kill 95% of them. That's 50,000 people: 2,500 men and 47,500 women. Let's be generous and say each woman has an average of 10 children (we're being outrageous, after all) before their bodies simply can't take any more. I'm not going to get too detailed, I'm assuming no generation produces within the time boundary of another. This means that when next the insects come, we have a population of about 525,000. That's HALF of the original count — and that's important. Because the insects take 95% again. I'm ignoring accidents, war, plague, and anything else that can kill a human. I'm assume 10 kids, no miscarriages, etc. Just the insects. Now we have only 26,250. Magically, 24,938 are women. Another cycle. Now we have 13,781... See the problem? We're being OUTRAGEOUS with humanity in giving them far beyond the normal possibility of surviving. In reality, they're extinct in 200 years. Max tech level: stone age. In fact, they probably regressed. **So, how much damage can my insects do and have growth?** A better child-bearing average is 4. I'm still going to ignore war, accidents, miscarriage, illness, and everything else (completely unrealistic, but enough for government work, as they say). I'm also not going to play the overlap as that woudl require more calculation than I want to put into it. The odds are you have basically a 1:1 distribution of men to women. Realistically, some would be too young to breed, others too old, but let's ignore that, too. How many can the insects take and have any population growth at all? (1,000,000 \* X)\*4/2 = 1,000,000 X = 50% MAX! Anything less than a 50% kill rate and the human race is extinct. It's just a matter of time. In reality, accounting for everything I said I was ignoring, your insects probably can't take more than 40%. I'm going to roll with that. Now, how much can we take and end up at, say, steam engines? Practical application engines came in the 1700s. Let's say 1700 for easy math. 40,000 - 1700 = 38,300 years. Insects every 20 years. 38,300 / 20 = 1915 generations. MASSIVE ASSUMPTION: If I end up with 50,000 people, I have a (barely) believable chance of inventing steam engines. So, I start with 1,000,000 and end with 50,000. How many can I take over 1,915 generations to get to this? I hated my statistics class... My gut says it's about 42% maximum. **Conclusion** What tech level humans can get to isn't really the question you want to ask. You can get to any tech level if the insects destroy few enough people every 20 years. Therefore, the real question is, how many people can my insects destroy every 20 years and get to a specified tech level? Steam engines: ~ 42% BUT! 1. Any declining population will result in extinction eventually. 2. Any advance in technology provides better protection against the insects. Franly, once we have fire (smoke) + caves, we have a way to save most of the people on every attack. **Final conclusion** By the stone age people can protect themselves. I've talked myself out of the believability of this scenario. Sorry. [Answer] **Insects are both bane and boon... and much worse for low-tech than for high-tech.** They're not ever going to knock people back down the technological totem pole, because 20 years is well within living memory. Any technology is going to be build with the assumption of once-every-20-years horrible insect swarms. Mostly, then, it adds another thing to the list of fundamental human requirements. You need food, water, oxygen, shelter, and protection from the bloody insects. The insects cannot possibly mostly feed on humans, because the humans are pretty much guaranteed to figure out ways to not be easy targets to insects of this variety, which means that there won't be enough human-based food resources in the environment for them to sustain the horrible ravaging swarms. So first you need to have the cavemen adapt to this, or the species dies out as a whole. Once you've got that, though, it's a matter of making sure that all of your buildings are insect-proof, and that every twenty years you've built up enough food to survive without going out much. For those times when you *must* go out into the swarm, people would be developing particularly thick clothing (leather, say) and facemasks - leave no skin exposed. The folks most likely to die would be the particularly poor - those too poor to have stored up food, or to have the thick clothes necessary to go outside in search of more. You might even have people learnign how to harvest fromt eh swarm itself. There are certainly places where locusts are eaten. You might see some technological slowdown, as it *would* take resources out of the economy, and technology has often been driven by nobles showing off using excess resources. Still, there's nothing saying that they couldn't get as far as we are now, just with somewhat more well=protected houses. [Answer] Sorry I can't comment on previous answers reputation too low but. Bug repellent comes to mind, which may have already been a possibility to prevent mosquitoes 77,000-38,000 years ago? As there must be some plant that the bugs can't stand the smell or taste of or an oil or sap that could be used. <http://www.earthtimes.org/scitech/plant-insect-repellent-stone-age/1697/> <https://en.wikipedia.org/wiki/Timeline_of_historic_inventions> [74] > > Wadley, L; Sievers, C; Bamford, M; Goldberg, P; Berna, F; Miller, C. > (2011). "Middle Stone Age Bedding Construction and Settlement Patterns > at Sibudu, South Africa". Science. 334 (6061): 1388–1391. > > > Colder weather may also help as Humans could migrate to colder areas during the attacks. Or pushing a bolder in front of your cave/shelter entrance providing the bugs are not in that cave. Handmade bricks came much later, 6000-7000 BCE <https://www.explainthatstuff.com/timeline.html> So I don't see a reason why there would be no advancement, but that it could be more delayed. It could possibly even encourage advancement by decreasing the time to have larger communities gathering under shared communal shelters. I would expect large covered shelters to be made, with retractable sun roofs and later glass windows. Later should the breeding cycle can be interrupted on a large enough area the insects could be wiped out. Can widespread outbreaks be prevented? Such as in real life. <https://motherboard.vice.com/en_us/article/z43x7a/how-to-stop-a-plague-of-locusts> This would make a great concept for story/movie/game would love to see this progress further. [Answer] Migration is the obvious answer to start with. Once it starts getting close to time, the tribe and it's livestock move into cold/mountainous regions where the insects don't go. As time goes by they develop food storage and barricade themselves in caves to wait it out and them barricade themselves in purpose built structures. They might also build rafts and ships and move out to sea to wait them out. Like all things, evolution will favor those who are adaptable. I doubt it would slow human development down much. ]
[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 6 years ago. [Improve this question](/posts/93773/edit) In a world where a "god" constitutes nothing more nor less than a critical mass of belief in a particular concept or ideal with a name plastered onto it. The gods are magical in nature being created by the magic energy derived from those who believe but the belief is the corner stone. Gods, when they exist at all, are physically invulnerable. Given this origin and definition how would someone, human, living in this world go about killing such a being? When answering assume a world with medieval levels of technology and universal but not uniform religion, magic is not a thing that happens in every day life but miracles are relatively common AKA magical displays are the exclusive province of gods, not men. Please note this is about an in-world solution not an author's solution to the problem at the havewaivium level. [Answer] I would say the way to do it is to make a more compelling, relevant story that supplants the target meme. Throw in some military and politics, and you can consider it eradicated, for practical purposes. If the idea needs a critical mass to support its corresponding god, then you don't have to kill or convert everyone-- just the majority. In Europe and the Middle East, people were polytheistic until a couple of monotheistic religions won the day through military conquest, politics (give up your gods and worship mine, and you can become part of the ruling class), and plain old persuasion. There are some people in Europe who worship old pagan European gods, but a direct chain of connection to the original worshippers doesn't exist. For all of them, from the Egyptian, to the Greco-Roman, to the Norse and Germanic, at one point, all of their followers abandoned that practice, and adopted Christianity. So, as long as you just need to keep below a certain threshold, a newer, more compelling idea might do the trick. For a modern-day example of this, you can look at [Santa Muerte](http://www.cnn.com/2017/03/30/opinions/believer-reza-aslan-santa-muerte/index.html): > > Santa Muerte, or "Saint Death," is a Mexican folk religion that > combines traditional aspects of Catholicism with ancient Aztec > religiosity to form a new faith. As the patron saint of death, Santa > Muerte is a kind of spiritual protector for a growing legion of > Mexicans who feel unprotected by the state and cast aside by the > Catholic Church. > > > In Mexico, it has become the religion of choice for transgender, gay > and lesbian worshipers, prostitutes, felons and drug traffickers, as > well as little old ladies, police officers, doctors, nurses and > judges. Santa Muerte followers say that death plays no favorites. Rich > or poor, powerful or peasant, death comes for everyone. > > > To outsiders it may seem as though Santa Muerte devotees are > worshipping death. But by embracing death, Santa Muerte believers say > they are free to live their lives without fear or anxiety. > > > The "old gods" of the state (okay, the state isn't technically a god) and the Catholic church (with God, Jesus, Maria, and a whole cadre of human saints) just aren't up to the task of taking care of people in certain areas of modern-day Mexico. A New God is arising. Arguably, she's gaining a sort of critical mass. For her followers, she is the force who truly has power over their lives. [Answer] That's pretty simple - kill the believers. At some point the number of surviving believers will drop below critical mass and the god will be no more. And that works just fine for medieval technology. See the Albigensian Crusade as an example of the suppression of a religion (or at least a religious sect). [Answer] I propose that an idea that such a being is dead would kill the idea. If everyone believes such a being is dead the being would be dead. Alternatively in Egypt great effort was spent to erase the name of former rulers from existence to wipe them from memory. Alternatively again if an idea is changed is it still the same idea. If such a being is forced to change with the belief is it still the same being Sorry to get an idea like this but you kind of led me there. [Answer] This is an active question in the real world, in the sense that political ideas have great power, and can't be physically harmed. Many people have at various times wished to kill ideas like communism, manifest destiny, Christianity, the comparison between sovereign debt and credit cards... it's notoriously difficult. It's a bit like trying *not* to think of a purple elephant. If you run TV ads telling people not to believe in Thor, you're just going to raise Thor's profile. If you persecute Thor-worshippers, you'll make them martyrs and strengthen their solidarity. You can maybe make people *dislike* Thor, but that's just turning a god into a demon. The one thing that seems to work is *replacing* an idea with something else that scratches the same itch, but better. People in the US stopped believing in railroads when they got cars. People in the USSR stopped believing in communism because capitalist economies were better at providing food and TVs. People stopped believing in bloodletting when (...etc.) If you ran an ad campaign for a new thunder god, who also gave out free candy on the summer solstice, and rode a flying laser unicorn, *then* people might gradually stop thinking about Thor. The trick is, you don't fight against an idea, you distract from it. [Answer] # Ideas may be bullet proof but they're not above corruption Ideas like gods are held by a group of people, accept them, welcome them in, consider their ideas and absorb them, but corrupt them. Take their god and make it an aspect of your own. Take their religion and make it a subsect of your own. Their god dies and is replaced by your god, their festivals become variants of your festivals. **It's very hard for a minority group to maintain an identity in the face of total and overwhelming acceptance of everything they stand for.** If you try to kill or oppress the idea you whittle believers down to a real hard core that hangs on and becomes tougher. If you welcome them with open arms they become soft and their true idea slowly fades into a memory of the old, the hippies, and the borderline bonkers. [Answer] One of the finest weapons of ideological combat is the word, "And". If you take any fundamentally legitimate belief and bond it to other, less defend-able ideas within the popular media, the strength and integrity of the original idea is lessened by the union. As the additions mount up, the idea begins to dissolve, transforming under the weight of all the extra baggage until it becomes a different idea entirely. When done over time, with consistency and authority, the bonds can become so lasting, that even after the original idea's collapse, its' name is forever bound to the failure of the union. This is better than killing an idea. This guarantees that the idea will stay dead. For example, if we start with the idea that Capitalism is the best economic model on the planet, AND then state that the best government should at least be able to take care of its elderly citizens; suddenly we are talking about "Capitalism AND ElderCare". If we then bring up that being the best, Capitalism should also take care of the sick and the poor; now we are talking about "Capitalism AND ElderCare AND Welfare AND Socialized-Medicine. With little additional effort, we've further redefined "Capitalism", appending it to include ElderCare, Welfare, Socialized-Medicine, Free-Education, Guaranteed-Employment, Fair-Housing, ...and every other social program we can think of. Each of these additions can appear to be made in pursuit of noble and humanitarian values. Each can appear to be attempts to "improve" upon the original idea. But if the appending is handled with care and diligence, the sum of these augmentations will slowly transform the original idea of capitalism, subtly changing it into the very different idea, socialism. In the OP's terms, the "Capitalism Worshippers" might still think they are worshiping at the "Shrine of Capitalism", but it would be the "God of Socialism" which receives belief credits for their tributes. Idea Assassination 101 : The word "AND" [Answer] Comments have referenced [Hogfather](https://en.wikipedia.org/wiki/Hogfather) by Terry Pratchett, where a deity is deliberately killed (or at least an attempt was made, which would have been successful without outside assistance). A deliberate attack on belief in that deity was made, so that the deity would die due to a lack of believers. A more interesting alternative from Pratchett is [Small Gods](https://en.wikipedia.org/wiki/Small_Gods). In that book, a deity nearly dies by accident. Even though its religion appears to be powerful, no-one actually believes in the god itself. To quote a quote within the book: "Around the Godde there forms a Shelle of prayers and Ceremonies and Buildings and Priestes and Authority, until at Last the Godde Dies. Ande this maye notte be noticed." With this in mind, it's interesting to look at how much of day-to-day life in Christian countries is based on the teachings of [Paul](https://en.wikipedia.org/wiki/Paul_the_Apostle). Paul of course was fundamental to the establishment of Christianity - but his more militant, proscriptive concept of religion appears very different to Jesus's, and in many ways he directly contradicts Jesus. So in your concept, it's entirely possible that Paul's corruption of original Christianity could have "killed" Jesus as a deity, because people who consider themselves Christian are actually following the teachings of someone else rather than Jesus. [Answer] I'd say fracture the religion. Many answers other than the genocide ones don't really kill those gods, but slowly merge or alter the god in some way. Sure, that same god doesn't exist anymore, but if one actually wants to kill a god instead of just getting rid of it that doesn't fit the bill. Say you have a religion that has 3 times the amount of belief needed to sustain a god. You could entirely remove that god by splitting the religion in at least 4 separate religions where none has enough belief to maintain a god. The question of course becomes at what point are two ideas different enough to be considered separate. This could be achieved either by inciting some mayor splits, or inciting minor splits. Inciting the mayor ones would probably involve some political manipulation. Inciting the minor ones however could be achieved by: 1. The hands off method: Things like a translating the holy book and spreading it so villages can create their own interpretation. Creating all sorts of mini-religions in the process. (Think printing press -> Protestantism) 2. The hands on method: Actively spread different religious information in different areas. You could also try to shift a Monotheistic religion towards something like Hinduism where the belief is spread over many minor gods. [Answer] In the world of Quantum Physics, yes. An idea is [information](https://www.theguardian.com/science/blog/2009/aug/26/entropy-time-arrow-quantum-mechanics) > > Is quantum mechanics messing with your memory? For all we know we may > live in a world in which windows un-break and cold cups of coffee > spontaneously heat up, we just don't remember. The explanation is > quantum entanglement > > > A hand wave, and send this entity to permanently and irreversibly travel back in time, second by second, instead of forward (living its entire existence in reverse, like playing a movie of its life in reverse) for all eternity, even past its own existence to the pre-existence of its birth. From that point forward in time there would be no record of its existence. [Answer] The idea exists and persists because of collective belief and constant reaffirmation. Attack—alter, distort, corrupt—the history, artifacts, stories, phenomena that are attributed to the deity and its creations, or certain groups' perceptions of them. Your protagonist engineers *(or completes the final step of)* the disintegration of a spiritually homogeneous society into warring factions, or at least until the "idea" is sufficiently diffused and rendered powerless. The entire process could span generations/centuries/millennia. [Answer] Take a look at Meme Theory (evolutionary theory applied to ideas.. originally by Dawkins). Memes can become extinct. I think the other answers here have probably arrived at the same type of answers you'd expect but the theory is much more broadly applicable and can be mined for the logical consequences of such a world, e.g. see the Red Queen Hypothesis.. which applied to this example would state something like "the most important thing for a god is the rate at which you convert". <https://en.wikipedia.org/wiki/Meme> There's also the idea of a Meme System.. which is a group of ideas that are all interrelated.. e.g. religions. The Meme System can also have its own evolutionary fitness (e.g. the Shakers were celibate.. arguably an unfit meme, and therefore an unfit meme system). [Answer] I remember reading a sci-fi fantasy story decades ago about something similar. I forget the title, author, and details, but it involved prayer rods. Each god had a specific type of prayer rod that the believers used to pray to it. The strength of the god came from the number of prayer rods and the people using them. The evil human protagonist set about to destroy the prayer rods, thus the followers could not pray to the god, thus the god and associated magic power weakened. I don't think the god died, because the hero mustered all of the followers to use whatever prayer rods were still in existence to strengthen the god, like the "I believe, I believe' chant that saved Tinkerbell. [Answer] In the real world ideas are generally impossible to "kill", we have people who are convinced the world is flat, even today, and you could point to literally millions of discredited ideas that are still in circulation. However, the actual number of people who believe in these ideas are small, and generally not very influential. Even in terms of religion, you can probably count the true worshippers of Thor or Athena on the fingers of your hand. The ideas are there (most readers probably have enough familiarity with these mythological concepts to be able to describe roughly who these gods were and their attributes), but no longer have any practical influence in the real world. OTOH the Abrahamic religions (Judaism, Christianity and Islam) have very real effect in the world, and worshippers of the Hindu pantheon are probably more than a billion strong. Even the Buddha exerts great influence in the modern world. So the issue here is discovering the "critical mass" of believers needed to sustain a god, and to then convert them to worship or believe in a different god, or failing that eliminate them so they are not available to provide the critical mass of worshippers. Way number two is distressingly common in history (crusades, Jihad, genocide etc.), but way number one is probably more effective. Since the gods are essentially personifications of ideas (look up the gods of the PIE ([Proto Indo European](http://www.ceisiwrserith.com/pier/deities.htm)) people's, many of them are personifications of things like the Sky). If you can clearly articulate an idea and describe it in a more compelling or clearer manner than the current deitiy explains the idea, then people will become attracted to the new and more compelling idea, and gradually abandon the older idea. In terms of your in story universe, the old god will fade while the new god will gain strength. Old gods may remain as pale shadows of themselves (much like Neil Gaiman's "[American Gods](https://www.amazon.ca/American-Gods-Neil-Gaiman/dp/0380789035)") The process is explained in the TV version like this: <https://www.youtube.com/watch?v=grTH-hf_0rA> [Answer] Hijack the religion. Religions are actually surprisingly flexible, providing that you can gather sufficient authority and support to lead them in the direction that you want. Gods do not seem to have much power over this, and there are plenty of examples of religions being manipulated and transformed into pretty much whatever is needed to justify any course of action - especially extreme actions like war and genocide. History has shown that the best way of controlling the people is to control their religion. Belief in a religion is not the same as the belief in a god. Steer the religion in a new direction and the people will follow, and the god will change or die (in godhood terms, they are probably much the same). Of course, wars generally are not much about religion at all rather than political ambition but religion can always be used to trump reason and responsibility and corrupt the most pious. <https://en.wikipedia.org/wiki/Religious_war> ... actually, that does not seem too dissimilar to some of the other answers. The point is that ideas are not immutable, they develop and change over time - sometimes slowly, sometimes dramatically, but even when the change is dramatic, people do not necessarily realise that it has happened - a jealous and vengeful god can turn into a god of love and compassion, and no one thinks 'well, it must be a different god!'. Of course, since in monotheistic religions there can be only one god, the god of retribution must also be the forgiving god - despite the rather obvious fact that one has been replaced (killed) by the other. [Answer] Ideas are overtaken by raised voice sometimes, ideas get muffled due to ignorance and lack of confidence. Ideas demand the open sky of belief, ideas needs the watering of hard work and patience. Ideas do not really instead they remain alive forever, and sometimes they do come back in the form of regret. Ideas are keys to success, but more importantly Ideas do provide experiences if followed and which are worth more than any money in the world. So no an idea cannot get killed!! :) [Answer] This question is likely assumed that 'God' is just an idea inside human mind. The earliest concept of "God" must had been forged/taught into our mind by our ancestors(in certain belief, they were called prophets/messengers). One of the concept(coming from certain religion) that It's a believe toward a supreme entity which created everything without being created. The origin concept of God define as an "entity", not as a "being", because it was not created. God is something in the very beginning of everything, and will be the end of everything. IF God was created, then it violates its concept as God. God is also the source of any beliefs, because any beliefs based on its God/gods. This source of beliefs, constructed and forged into the heart as belief and into the mind as concept which supervise our self and create certain culture and way of life based of that source. The thought that God must exist came from the impossible of things in the universe to be what it is now without any trigger/creator. Beside, the inability of human to create another human, create anything alike in this universe. There's must be somekind of power that handle all of energies and matters in this universe, and that power some people would refer as entity called God. Back to your question. If we assume it's as an idea. You cannot really kill it. Because once an idea pass into human mind, that idea will be reside there, and eventually spread to any capable brain holding such idea(human brain). Hence, the only way based on your question is to kill ALL human ever existed in this world(including your self). ]
[Question] [ Ejaculation is the discharge of semen from the male reproductory tract, usually accompanied by orgasm. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. Despite this, "dry" orgasms do occasionally happen. This occurs when the final stage is reached with no actual discharge due to the testes having run out of juice. This species of humanoid is similar to baseline homo sapiens, with a few key differences. I would like to design a mechanism for voluntary control over the discharge of semen, like an on or off switch that can be activated at will. This would be meant to be a natural and foolproof form of birth control and eliminate the occurrence of unwanted conceptions. How can I make this possible? [Answer] You can you go two ways, I think. **Way 1:** Sperm production follow a periodic cycle, roughly like egg production in the female does. This means that only intercourse during the right moment will be fertile, any other time will be non fertile. To prevent extinction of course you need a synchronization of female and male periods. **Way 2:** The male has to consciously decide for emitting semen, something along the line of the western interpretation of tantric sex. A muscular contraction at the right moment can simply stop the seminal emission. [Answer] # Abstinence Not having sex is a "voluntary control over the discharge of semen." It is also a "natural and foolproof form of birth control and eliminate[s] the occurrence of unwanted conceptions." If you don't have sex, you won't have kids. [Answer] [Retrograde ejaculation](https://en.wikipedia.org/wiki/Retrograde_ejaculation) > > Retrograde ejaculation occurs when semen which would, in most cases, > be ejaculated via the urethra is redirected to the urinary bladder. > Normally, the sphincter of the bladder contracts before ejaculation > forcing the semen to exit via the urethra, the path of least > resistance. When the bladder sphincter does not function properly, > retrograde ejaculation may occur. It can also be induced deliberately > by a male as a primitive form of male birth control (known as coitus > saxonicus) or as part of certain alternative medicine practices. > > > You want some deal where the men can fulfill their culturo-evolutionary imperative to have lots of sex, but shortcircuit the fitness benefit that it historically provided. That will work until mutant men who can't do the short-circuit overwhelm the population with their progeny. But in the short term, your men can be yogi masters (if that was not already the case) with conscious control over the bladder sphincter. Sex occurs normally, with the ejaculate captured in the bladder to be voided against a tree at some later time. Out of distaste for banality, I hope you make these men and their partners be capable of all sorts of other yoga sex tricks too. [Answer] These are humanoids so we don't have to modify human men. In their society males, like seahorses raise young. **Male seahorse giving birth** <https://youtu.be/MsHCqrrU-Gk> This is very energy expensive so males don't want to be having offspring all the time. However females will wander if they don't get regular sex. Therefore, through evolution, the males have a mechanism for ejaculating only when their previous brood is self-sufficient. [Answer] Intelligence has allowed mankind to thrive, and your humanoids might have evolved it out of a necessity. First option: disease. We already have a common disease that has a ludicrous chance to kill an unborn child. Biology found a solution: kissing. By kissing you exchange saliva and if the man has the disease he'll infect the woman. By the time the disease becomes dangerous to the baby the woman has created an immune response and the baby is safe. Now imagine a disease that primarily lives in the reproductive organs and the man will have an idea when he's infected during sex. The disease works like the flu and changes each year, so you dont stay immune. If the disease survives long enough to have a high chance of killing the child the man can choose not to ejaculate but continue sex normally to both increase the chance of infecting the woman and give her time to become immune and for the social benefits of sex. The second and more elaborate option: Imagine a world where there are large stretches of time where unborn children and babies have almost 100% chance of dying. Its a waste of time, energy and potential children as you need to recover after a failed attempt. If these stretches of time are happening at predictable intervals biology would simply adapt the cycles to those intervals. If they arent predictable only two solutions remain: Make sure your biology can create children at a rapid pace or become intelligent enough to learn all the signs when children wont be viable. For potenial comments like "biology would learn the signs of the event and not need intelligence" there would need to be several events that seperately may not cause death in the babies but combined would cause that death. Sex would still be used as a social interaction between the man and woman in those times children shouldnt be born, but to ensure no babies are born the man would prevent ejaculation. [Answer] We humans are capable of doing it. Millenia ago the people in India developed some traditiond which are called [Tantra](https://en.wikipedia.org/wiki/Tantra). Among such traditions, there is tantric sex. Search on Google or Amazon... There are thousands of books on it written just this century. Central to tantric sex for men is developing the ability to have dry orgasms without being dry. This is done through breathing and muscle control, akin to (or including, depending on the view) yoga practices. It is said to become second nature once you achieve it, and allows for a man to have multiple orgasms. [Answer] **Proceptive** (?) **medication** - Males have to take a drug to produce sperm/gametes or one of the other necessary components of semen. I'm envisioning something plant- or fungus-based... Your early hominids live in an area where this organism is plentiful--so plentiful that they never really have to think about actively producing sperm. Some males don't like the taste, so they rarely eat it and maybe never have children or have very few. Groups that splinter off and leave the home area only reproduce if they move to an area where the same plant grows or if they take the dried fruit with them. Maybe they aren't consciously aware of it, but there's definitely a connection between the fruit and reproduction. They might even have a sex/harvest festival when the fruit ripens. Over time, as agriculture improves and your hominids explore their planet, their diet becomes more varied, the sperm fruit is less of a staple, and the birthrate slows down. It has become a cultural tradition for explorers to always carry a potted sperm plant with them. Sailors have been known to mutiny and force their captains to turn home whenever the potted plant dies. Horticulturalists attempt to create sperm fruit hybrids and succeed, introducing more variety into both the plant and the hominid species. Perhaps the sperm fruit plant is very climate-sensitive. That could be a form of natural population control. In lean times, the plant and the population don't grow as much, so there are fewer new mouths to feed. And it could lead to developing trade between groups that live in areas where the plant will grow and the areas where it won't. This sets up a few different scenarios. 1. A global climate catastrophe wipes out 90% of the world's population. Maybe only half of that is wiped out by the actual disaster. The rest simply live their lives and die without the ability to reproduce. Only those isolated areas where the plant can grow have thriving populations. This could lead to development of cultural variations. 2. Politics vs. Science - Your hominids have established a clear link between the sperm fruit and reproduction. Now there's a race to create a shelf-stable synthetic version so that they're no longer dependent on the fruit. The government tries to control growth and distribution of the sperm fruit, causing groups of rebels to periodically attempt to steal the plants and/or overthrow the government. 3. Space drama - Your scientists haven't yet succeeded in developing alternatives to the sperm fruit. Or they have, but the synthetic version has a short shelf life/is costly to produce. Space colonists must take living sperm fruit plants (either in stasis or specialized terrariums) with them on their colony ships. An alien attacks! A meteor strikes the ship! All but one of the plants are destroyed, and that one is damaged! What will they do? Will the colony survive? The ships's horticulturalist was captured in the attack--will they be able to get him back? Can his daughter, who's angry at being ripped away from all her friend back home, decode his notes and heal the plant? Watch the drama unfold!!! [Answer] The testes have a muscle called the cremaster, that pulls them up whenever it's too cold to maintain the right temperature for spermatogenesis (the process which sperm cell are produced), or relaxes to cool the testes whenever it's too hot. Have this process be a lot more temperature dependent, working only when the testes are around the temperature of the body. The cremaster muscle should not be an independent muscle, or involuntary. It should be a voluntary act to contract or relax it, depending if you want to be fertile or not. In this system, you need to pull the testes in advance, maybe some hours prior to sex, in order to have functioning sperm cells. Although you'll have no chance of conception, semen will be produced normally, as the majority of its components is not produced in the testes, but on different locations of male genital tract. [Answer] # Look to the bladder. The male urethra has two purposes: the ejaculation of semen and the elimination of urine. For most men, these two functions are mutually exclusive; it is difficult to maintain an erection with an extremely full bladder, and urination becomes very difficult when a man has an erection. Brief anatomy lesson: the urinary and reproductive tracts meet inside the prostate gland, which surrounds the urethra and rests directly below the bladder. The vas deferens carry sperm from the testicles to the prostate, where they merge with the seminal vesicles and join with the urethra via the ejaculatory ducts. Downstream of the prostate lies the smaller bulbourethral gland. Human urine is acidic and poses a threat to the health of sperm. The bulbourethral gland secretes a slightly alkaline fluid, often colloquially referred to as "precum", which neutralizes the urethra prior to ejaculation. Semen itself is also slightly alkaline in order to neutralize the natural acidity of the vagina. I can think of two ways that we utilize the confluence of these two systems to achieve the desired effect: 1. Males of your species are capable of urinating and ejaculating simultaneously. If the urine of your species is sufficiently acidic, it will kill the sperm before or shortly after they leave the penis. 2. Males cannot urinate and ejaculate simultaneously, but can choose to urinate at any time and the act of urinating forcibly closes the ejaculatory ducts. In my opinion, this is the more reliable and realistic solution, since the closing of the ducts would prevent urine from entering the vas deferens where it might damage future sperm. However, the sperm would probably leak out afterwards, so caution would need to be exercised in order for this to be truly effective. [Answer] Just rewire the brain. Ejaculation requires muscles to move. Remove those muscles from autonomic control based on emotional state. Provide that control to the motor cortex in a similar fashion to moving a finger. To explain why: * Moral, it is unseemly for a man to not control this. Those that can't are shamed. Many young boys undergo the therapy/procedure as babies/children because there parents wish to avoid future shame. * Political, an edict by the government forcing boys without the genetic mutation to be killed. Maintained for numerous generations has left the population mostly/entirely in this state. * Evolution, controlling this provides a cost/benefit. Perhaps the smell attracts the wrong kind of predator, or disease. Perhaps the capacity to remain virile reduces quickly with proportion to ejaculation. ]
[Question] [ The current technology around this subject is somewhat hard to gauge. For obvious ethical reasons, there is not a lot of empirical precedents. Also, given that it's subliminal, it is by nature difficult/if not impossible to perceive for the targets. For these reasons, extrapolating into the future (50 years or so) seems quite challenging. I'm trying to convey a dystopian near-future earth where people are forced to undergo weekly subliminal programming: **Platform:** VR Headset, immersion chair set **Media:** static, ultra-fast-paced video (chaos to the conscious mind, only registering with the subconscious) **Duration:** Uncertain, 1-2 hours / week? **Age Group:** People of all ages **Goal:** to pacify people and implant social directives for them to live their life by. (who they can be friends with, what topics to talk about at lunch, ect) **Other notes** May be used in conjunction with sedative medicines / hypnosis. **Effectiveness Metric** Effectiveness is the feasibility of achieving the goal: pacification/instilling social directives. The goal is not to make them brain dead, although I don't know that much about psychology, maybe that is what would end up happening anyway. So my question is, **given what we know about the bleeding edge/ frontier psychology today**, can my sci-fi plot hold up to a discerning reader? In your answer you can include how far such a facility could brainwash someone. I realize we cannot 100% know, but thoughtful speculation is welcome. For example, you may gauge part of your assessment of the degree of brainwashing on a continuum -- would they wind up being total vegetables, or would it be more of a joke (no effect). This will help me figure out how much creative liberties I need to take in order to fill the technological/psychological "gaps". [Answer] Directed subliminal brainwashing is not possible. Sorry. The thing about ultrafast video isn't that it's "chaos to the conscious mind, only registering with the subconscious". Most of it's going to be thrown out as garbage by the visual cortex (before it even reaches the conscious or subconscious mind). Anything that *does* reach the subconscious won't necessarily be what you *wanted* to reach the subconscious. And even if what you intended reached the subconscious, it's not necessarily going to be *interpreted* in the way you want it to. As it turns out, humans are *really* bad at interpreting their own emotions and behaviors. An example: researches had test subjects (all male) traverse one of two bridges over the same gorge. The first bridge was made of stone, broad, and solidly made. The second bridge was an incredibly rickety wooden bridge. At the end of each bridge was the same female "researcher" who gave them a survey. Later, test subjects were asked to rate the attractiveness of the female "researcher". The female "researcher" was rated as *more* attractive by the subjects who went across the rickety bridge. The subjects misinterpreted their *real* feelings (I'm getting a real adrenaline rush from this terrifying bridge) into a vastly different interpretation (I'm getting a real adrenaline rush from this woman who's talking to me). Any guy who's taken a woman to scary movie on a date is operating under the same principle. Now, turn this about into subliminal brainwashing. What exactly do you think is going to happen when you pump chaotic signals into a human? Say you have a simple goal (even though your stated goals are actually really complex): vote for politician A, not B. So you try and do things like pairing *happy* images with politician A and *fearful* images with politician B. Except, as we've already established, it's chaos, so not everything's getting through. Maybe you lose your happy images. Maybe a "neutral filler" is actually the phobia of the subject and gets paired with politician A. Maybe you pair ice cream with politician A, and the person *likes ice cream less* instead of *politician A more*. And this isn't even your biggest problem. Your biggest problem is that you're strapping someone into a VR headset for some amount of time and piping noise into their face. The number of people who don't just shut their eyes for the duration is going to be tiny. If you pry open their eyelids, they'll do their best to ignore it (and we're really good at ignoring things at the visual cortex level, i.e., before the subconscious). Essentially, you'll be providing the same experience as sensory deprivation by way of sensory overload. If you don't do this for very long, you'll make people *angry at you* but otherwise unaffected. If you do it for too long, they'll just go insane. [Answer] # 100% effective method. Allegedly in use in... [China](https://www.aclu.org/blog/free-future/chinas-nightmarish-citizen-scores-are-warning-americans) [citation on effectiveness needed; intended as humor] Here's how. **Optional Step 1:** Heavily criticize any opposition to the government. In all forms. This will make step 4 easier. **Step 2:** Introduce your citizens to social media. Basically, create Facebook or an equivalent. Regulate it lightly, you want people to like it and use it. A lot. **Step 3:** Introduce a new "social score" feature that allows people to vote up or down various posts. Allow anyone to query anyone else's score (e.g. display it prominently on their profile page). **Crucial Step 4:** Every vote impacts not only the poster *but all of the poster's friends, family, and other network connections.* **Step 5:** Mandate participation, no ability to opt-out. Link this score to their offline identity, e.g. their social security number, driver's license, etc. Treat it like a credit score: users with low scores can be legally denied jobs, loans, and other services. Users with high scores can receive preferential treatment, such as fast-pass visa access to leave the country. By making a user's social score dependent on their friends and family, it becomes a lot harder to speak out as you'll be quickly hushed by your network connections as *they* don't want to be impacted. Anyone who does continue to speak out will see those network connections severed and be effectively isolated and ostracized. As that feeling of loneliness is *already ingrained in the human brain* (we are, after all, social animals) people will *brainwash themselves* by only saying things that will raise their social score. And the only thing that will raise their social score will be the things that the government wants you to say. **Will anyone notice? Is it actually subliminal?** Well, *People* would be flocking to their version of Twitter to post and be proud of their high scores. Everyone *outside* such a country would be horrified. But notice that once the system is implemented, the *government itself* never needs to step in. Instead the system is self-regulating. Majority opinion will dominate and continue to dominate due to the isolating nature of negative reception. The government can actually claim that no, they are not suppressing alternative political views, the system is in place to punish people who talk about murder, or child pornography, or sharing stupid memes *because they're **stupid*** and no one wants to see that garbage. It's not **their** fault that people are down-voting radical ideologies, but if people feel that that isn't what they want to see in their feed, that's their prerogative. End result: a population that thinks what you want it to think. And they did it to themselves. Sooo... maybe? [Answer] (EDIT: purposefully ignoring the "subliminal" part.) Given how effective *current* brainwashing (aka "advertising") techniques are -- because of the billions of dollars spent by advertising agencies on psychologists -- I'd say it could be *spectacularly* successful. Caveats are: * Current brainwashing techniques are relatively voluntary (most people *choose* to not actively pursue media with no advertising), * brainwashing must be *Subtle* with a capital S, using people's base desires rather than ham-fisted govertment decrees. * 30 years of multiculturalism means that society is a lot less homogeneous than it was 50 years ago. Brainwashing thus will have to be culturally sensitive. * There will be a noticeable minority on the Left and Right who will resist the standard methods. They'll have to be handled with different techniques. [Answer] My answer will be boring, but I'm afraid true. **Given what we know about subliminal stimuli - we don't know**, with bias towards no. Subliminal message can't change response to commercials in any measurable way. [[link](https://dx.doi.org/10.1037%2F0021-9010.79.6.866)] There are reports that shows subliminal stimuli to be able to bias choice between options someone was already considering anyway. [[link](https://link.springer.com/article/10.3758%2FBF03196596)] There is no consensus **if** this kind of stimuli **works at all**. At the moment, you can say it does, or you can say it doesn't, and it will be believable and you will find scientific papers to back you up. However, given how weak it is if it actually works, you shouldn't expect any drastic changes in behavior, these wouldn't be feasible. [Answer] As other answers have pointed out, subliminal programming in the traditional sense (show people a bunch of images too quick for their conscious mind to process but which somehow sink into their subconscious) has no proven record of working. However, it *is* possible to adjust people's behaviour through other methods of varying effectiveness and subtlety. The example of the Chinese "social score" given by Draco18s is an almost gamified version of the kind of social pressures used in many communities, especially more oppressive ones. Such systems can be susceptible to being gamed though - once people see their "score" as being the important part of the system, they will tend to act in ways that benefit the score even if they're not the kind of behaviours the designers wanted to incentivise; a classic example of such gaming is when governments have tried to combat rodent infestations by paying rewards for people bringing in rat corpses, which just results in people breeding lots of rats. Perhaps closer to the idea you're looking for would be varying ideas of training the behaviour into people. There's stuff like hypnosis (which is not quite as effective as the movies would have you believe, but which applied over a long period of time could give you the desired results), possibly enhanced by drugs; or conditioning as studied by Skinner and Pavlov. The general idea of conditioning is that you reward desired behaviours and punish undesired ones, although Pavlov's version was more passive (getting the subject to associate two events with each other) while Skinner's was more active (getting the subject to associate their own actions with a particular result). If you combine the things, then you might get a process like: * Somehow expose the populace to a chemical that makes them *slightly* more open to suggestion. * Get them to come in to a government centre on a weekly basis for some kind of "standardised aptitude testing". * Make the testing a VR game, and in addition to testing reflexes or whatever make there be a number of social choices the player must make. You can throw in some kind of techno-babble about how being in a state of hyperconcentration reduces your ability to reject ideas that go against your better judgement. * When the player does well in the game (good reflexes *or* choosing a desirable behaviour), give them both an in-game score and some kind of pleasant external stimulus. When they do poorly, reduce their score and give them an unpleasant stimulus. * Repeat this as much as necessary until they have internalised the idea that "doing what you're supposed to = feeling good". Make sure that the earlier stages of the game involve choices where the right and wrong behaviours are already understood by the players, and then gradually introduce the stuff that you want them to take on as desired behaviours. So in early stages you stick with stuff like "hurting other people = bad" and "picking up litter = good", then after a while start putting in things like "turning traitors in to the police = good" and "voting for anyone other than the ruling party = bad". At the same time, you can link performance in the tests to social standing. People with good scores get a bonus from the government, or some other kind of preferential treatment, while people with particularly bad scores get recommended for some kind of remedial community service (you might even have the government fake some kind of study that suggests that low scores are related to likeliness of criminal behaviour, or something). This is probably only slightly impossible, as opposed to the completely impossible nature of subliminal programming - research is still a bit on the fence about what extent being exposed to particular kinds of media affect our behaviours, but if it's all about making small changes that add up to something larger then it's a bit more believable. [Answer] Two points... 1. In this particular crowd I suspect you may find an overabundance of skeptical people who may not reflect your target audience. 2. If you want to sell it to a readership you have to base it on things that they believe and understand. As many have noted commercials are masterful at manipulating emotions. If you use social status measures as a basis and throw in a presumption you can gauge emotional responses to visible stimuli and adjust programming on an individual basis I don't see why you couldn't sell it. All you need is a incentive/disincentive to ensure your society watches their programming regularly and assume there is an additive effect that gets reinforced by societal forces while they are not getting programmed. At the same time, if you going to such lengths you could engineer the disappearance of truly problem citizens who are not acting appropriately in society -- whether or not they respond to their "treatment" appropriately. Some basic examples that someone with writing skills might be able to develop into something interesting... * User is given cues or scenarios, user reacts appropriate to or makes choices in VR, user gets a more enjoyable session and social accolades (riches, recognition, attention, etc) in VR or possibly outside VR based on some criteria with possibly longer lead times. * User reacts inappropriate to or makes a bad choices, user deals with unpleasant experiences due to happenings in VR (and you know what the user finds pleasant or unpleasant based on sensors and cameras involved in their VR experience). Possibly engineer some bad luck in their day once in a while depending on severity of transgression. This of course gives you some insider elites who help bring tie in the VR conditioning to the real world and provides you with a bit of "A Scanner Darkly" in terms of people on the inside who may represent a weak point against whoever might be working against the regime. Perhaps "enforcers" are fed targets by showing them VR crimes that they are supposedly involved in... such that people may believe they are doing the right thing when they are culling folks that are breaking down the general society norms. Note, you can walk back and forth between subliminal and perceptible inputs as you like. In short, most sci-fi is not truly plausible (regardless of whether or not much sci is involved). Aim for difficulty in disproving the possibility of plausibility and you've got a lower bar that allows your audience to get entertained by your ideas. I really hope you are writing a fiction and not implementing the next social order or I've done humanity a disservice. [Answer] **I think the simpler methods are the most effective.** This is already possible. Look at the effects of the main stream media over the last 30 to 40 years. The key to brainwashing is symbolic shifting of meanings and the break down of norms and standards people hold within their minds. **Symbolic Shifting:** Symbolic shifting requires that you redefine the meaning of things. If you re purpose a symbol to mean something else, you can, over time, change the loyalty of those who follow it. One day, the flag represents freedom and individualism. Over time, you change it to represent communism and mediocrity. However, people are still pledging allegiance to the same flag. You have re purposed the symbolism of it to mean something else entirely while retaining the loyalty "to it" rather than to its meaning.Now you have a dictatorial army rather than a free people's militia. Both pledge to the same flag, both take orders from the same authority, but now they fight for totally different end goals. The media does this with words and symbols constantly already. **Breaking Down Norms:** The second way is to break down norms, thus inhibiting one's capability to question inconsistencies or morally objectionable material. Normalizing things that have traditional taboo is a prime example of how this happens daily around the world. If everything is "normal" then nothing is "abnormal" and questioning such abnormality is then indicative of bigotry or mental illness since abnormality would not exist.Such equality is not used to obtain individual equivalency but rather remove all culture of criticism and competing thought. **Real Weaknesses:** Together, both of these would brainwash a large number of people over time. The key word here though is time. These methods, while simple in concept, must be implemented subtly over a long period of time. Too fast and they can see through it. A second weakness to the above methods is perspective. If you have free speech, or an internet or some other massive democratic means of information transfer, the inconsistencies become much harder to hide despite the subtlety with which they were employed. Eventually the truth wins out when information is allowed to freely aggregate. The only counter to this is to remove free speech or inhibit people's ability to communicate effectively. Again, you see this happen daily around the world- even in first world countries. They limit free speech, bully people away from the truth, hide details, etc. Doing so is the only way to maintain the illusion. Weaknesses are important. These are what allow societal change in your setting. The rebels use these weaknesses to gain followers and become free of it themselves. By using a real world context, you get real world weaknesses to work with. Such are good for believable limitations. This is obviously not a "Sci-fi" approach, but I don't think such approaches are believable, and those that are somewhat believable are quite cliche at this point. A more nuanced and down to earth method of believable brainwashing will yield a more holistic setting in my opinion. [Answer] What you describe is perfectly plausible as a sco-fi scenario, and would hold up in any novel or movie I'm sure if it were spliced with a degree of originality and litarary skill. However, the idea of a passive, non-violent, possibly benign method of significantly altering the will of a healthy and functional human is highly unlikely. Especially if "covertly" was another box you wanted to tick. What would work, and has "worked" to a marked degree, is Pain-Drug-Hypnosis. This is a violent and I'd say barbaric method of altering the will and actions of a human being, which was the subject of MK-ultra and other such experiments, historically we hope. The story line of the Jason Bourne franchise is I believe pretty close to where MK-ultra was heading. But the act of reducing the self-determinism always comes with a price. It seems you can't subdue, trick or short circuit the spirit of man, to the point where he'd do something against his original will, and expect him to continue with anything approaching normal functionality. In my humble, but considerably wise and well informed, opinion! ]
[Question] [ **Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- Questions about Idea Generation are off-topic because they tend to result in list answers with no objective means to compare the quality of one answer with the others. For more information, see [What's wrong with idea-generation questions?](//worldbuilding.meta.stackexchange.com/questions/522). Closed 9 years ago. [Improve this question](/posts/4521/edit) One day, "God" said to me: > > You need to eliminate the humans race! > > > So, I was thinking at this problem: How can I kill every human on the planet (and then kill myself)? Some ideas: * **Nuclear Bomb** - Bad choice.. Very difficult to build and A LOT OF PEOPLE will survive to the explosion. * **Diseases** - Bad... Always will have people that are immune to it. The best idea so far was: > > Build an ideology that say everyone will be happy. And then kill for it! Like Mao Tse-Tung, Pol Pot, Hitler, Stalin, etc.. But even they did not even kill 1% of humanity. > > > So, what is the best strategy to do it? [Answer] I can't help myself. 1. Tell God to click that 'Halt Simulation' button - SE solution 2. Wake up whomever is dreaming us - Waking World solution 3. These aren't the humans you want to destroy - Jedi solution 4. Trans-locate God to parallel dimension where humans are already destroyed - 'The One' solution 5. Redefine 'humanity' to only include the guy standing in-front of you. Shoot him. - Semantics solution 6. Put rockets on Earth and slow its orbital velocity to 0, watch Earth fall into the Sun. - Physics Schmysics solution 7. Ask God to put in a trouble ticket and hope the problem disappears - Help Desk solution (attempting to redefine humanity as a feature may fit in here) 8. Invent Skynet. Implement Asimov's fourth law as "Ignore other laws, kill all humans". [Answer] ## Part 1: Reduce the human fecundity worldwide The best way to ensure that eventual survivors can't repopulate the Earth is to make sure that they can't reproduce. 1. Do your best with genetic engineering. Create a huge variety of very different viruses that lead to human infertility but no other detectable symptoms, and make it transmissible by air and sexually. Make them transmissible to mosquitos, pigeons, cattle, rats, bats, cats and dogs, to ensure massive virus circulation. Make sure that the viruses spreads and infects people quickly, efficiently and silently. BONUS: As suggested by @Henry Tailor in another answer, make the viruses induce production of pheromones on infected people, so they are more attractive than non-infected people. 2. Spread the viruses everywhere, in every city, town or indian village. You may simply convince or pay people for doing things that leads to that or maybe use a more technological approach and spray 'em with drones. 3. It will take some years for the scientists to understand what is going on and to discover, study and analyze the viruses. Many more to propose efficient ways to prevent further infection or promote efficient and widespread vaccines. Further, you designed a lot of very different viruses, not just one, so it is very unlikely that people will be immune to all of them. And they will need to be discovered, studied, analyzed and vaccinated independently each one in its own way. 4. When people becomes aware of the existence of at least some of the viruses (likely something between 2 and 8 years after you started to release them), spread misinformation about them, including misinformation in scientific reports and articles. Spread the type of misinformation (like fake news) that makes people paranoid, skeptical and more likely to spread the virus, and that also slows down scientific investigation. 5. Try to kill any scientists that are publishing seriously breakthrough work and studying what is going on. You may shot them down, poison them, trample them in the street, whatever. Make it looks like an accident or that some crazy fundamentalist guy (not you) did that. You will be unable to locate some of those scientists and it is hard to know what everyone is researching, but each kill is a point for you. Looking for people attending conferences on related topics is a great way to locate them. Now, the fecundity drops worldwide, and fewer and fewer babies born each year. The scientists will start to work on it, and in-vitro fecunding will be a high profit business, but this is too few time (2 to 8 years) to efficiently address the issue or even to make everyone fully aware and non-skeptical, specially with widespread misinformation. So, it is time to go to part 2 before the scientists make further progress. ## Part 2: Destroy the economy and make war People need food to live. With few food available, people will die from hungry, and kill from hungry too, starting wars, crime and violence. 6. Atomic bomb major cities everywhere, all about the same time. 7. Spread orange agent, radioactive elements, poisons and/or viruses in plantations, waters and forests all around the world. This would make safe food really scarce. 8. Make each nation blame another one for the bombings and the destruction of crops, spread misinformations, fake news, manipulate media. This will trigger WW3. Now the industry, the production and economy will be seriously damaged everywhere. The world is at the greatest war in the history. A lot of people dies. Survivors are struggling in the ruins, without anything safe to eat or to drink, people will run away to the countryside destructing whatever left from the economy there. The fertility problem is regarded to a second-plane and no one will be able to continue research on it anymore. There is just anarchy, crime, war, violence and misery. Further, the chaos and anarchy will strongly benefit the spread and circulation of the viruses by moving a lot of people and resources around. People will likely disrespect any safety measures previously adopted to avoid further contamination, since getting food and water is always more important than this. ## Part 3: Game Over In a few more years (let's say 15 years) at least 98% of the pre-existing population will be dead, and most of the survivors will be in bad health, miserable conditions and unable to have babies. 9. Now you just need to chase any possibly reproductive survivors. The easiest way to do that is to use drones to look for kids. When you find a kid, just shoot them (use your drones for that) and look for their parents somewhere around, and shoot them too. Or better, just shoot everyone alive, except if you guess that he/she might unintentionally show you where other survivors are hiding around, paying special attention for kids, then kill everybody. If you suspect that they are in a larger tribe or family, bomb the area for some days, search carefully using the drones and drop some radioactive dust in the area. After a few more years, there would be no more than a few handful survivors around, probably less than 1000 in the entire world. They are too scattered, hidden and fearful to recolonize the planet, even if they have any mean to communicate. Even if a few kids survive and reach adulthood and can reproduce, they are still too few and too scattered to make the human race survive, so the humans will become extinct soon. Mission accomplished. It took something like 20 to 30 years, but it is finally done. Now the last step: 10. Kill yourself (as demanded by the OP). Note: Obviously I do not support anything of this. I am writing this like a film or game maker, and not because I believe that. [Answer] A lot of credit goes to Peteris for turning this answer around. I'll go with some kind of bacterium (or virus; I believe it works in this scenario) that stops photosynthesis in plants. Typically, chlorophyll can only be destroyed at low temperatures. That's a problem, because you can't drastically lower the temperature of a plant! But you could attempt to destroy the chloroplasts, the structures that contain the chlorophyll. My suggestion for this would be to create a virus that hijacks lysosomes - the organelles in a cell that break down other organelles - and breaks down chloroplasts. There is a problem - [plants don't have lysosomes](https://en.wikipedia.org/wiki/Lysosome#Controversy_in_botany)! However, vacuoles may be able to do the job. If you can destroy the chloroplasts, you can kill plants, and thereby the entire food chain of Earth. It might not happen within 50 years, but perhaps it could work within a century. Note: I asked a question on Biology regarding the feasibility of the original process described in my answer. It can be found [here](https://biology.stackexchange.com/questions/24291/can-an-organism-process-h-2o-into-h-2o-2). [Answer] Spontaneously, I see three approaches: **Diseases** First off, to everyone saying diseases aren't capable of eradicating the human race: You obviously never win at [Plague inc.](http://www.ndemiccreations.com/en/22-plague-inc) °v° Seriously though, diseases are a bad choice. While you might be able to kill a good percentage of the humans with some resistant killer virus, the infection rate would gradually slow down when the number of humans decreased, thus decreasing the number of chance meetings and resulting infection in combination with the fear of those remaining healthy, causing them to stay isolated and avoid infected people. (Take a look at the [this article](http://ic.galegroup.com/ic/suic/ReferenceDetailsPage/ReferenceDetailsWindow?zid=11d616917c0a0f5ee6b8ca9018471361&action=2&catId=&documentId=GALE%7CEJ2181500192&userGroupName=clov94514&jsid=1276d8bbb5aa3ac8e1818f0d2be323d1) on how the Black Death came to an end, though it's not scientifically validated) I don't think that this fits your question, but a zombie virus might be a workaround for that problem (the atheist in me says that if God does exist, zombies might as well) ... **Natural Disaster** Natural disasters like climate change, floods, asteroids and such are in my opinion the surest way to kill all humans. Depending on what disaster you choose and how good you plan you might kill all of mankind in one single day (imagine [2012](http://en.wikipedia.org/wiki/2012_%28film%29) if nobody had had a clue about what was going on) or at least get a good part of the job done. However, your means of invoking something like that are very limited (which might be the reason we call them *natural* disasters). I think one way would be to enforce an ideology that advances the exploitation of natural resources, which will eventually lead to said disasters (we've all seen An Inconvenient Truth, haven't we?). However, this would take more than one lifetime and is kinda hard to execute as well. **World war / Nuclear war** "I do not know how the Third World War will be fought, but I can tell you what they will use in the Fourth — rocks!" (Albert Einstein, probably) ... which would be unfortunate, since that would mean that there were still people around to wage world war IV. However, inducing a worldwide open war would promise a maximum of destruction and death amongst humans. This could as well be approached by means of ideology (or religion, respectively) and deceit. But the person behind should not be some Russian guy trying to punish the West for ... being evil, I guess. Because this story has been told in, like, 10 Call of Duty games or so. So far. All in all, there is no foolproof way to eradicate mankind ... which is a good thing, I guess. Maybe you could combine the methods mentioned above, or consider using fantasy or sci-fi elements (like magic or large-scale destruction weapons). After all, I hope you're asking for a story and not because you're actually seeking advice on how to kill us all °ω° [Answer] Be glad doing so isn't easy, because if it was easy, someone would have done it already. Perhaps the best sure-fire way to kill every human might be to... * Build a multi-billion or multi-trillion dollar fortune * Invest heavily in space exploration * Found a colony the Moon * Build a *huge* mass driver capable of launching massive chunks of rock * Pummel earth until tender. It may take a while, because humans can be scrappy, but eventually you should be able to get them all. Especially if you wreck the eco-system enough. Oh, and don't forget to take out those pesky stragglers in orbit. Once you have completed your task, vent the atmosphere in your moon colony. [Answer] **Extreme Climate Change** And by extreme I mean really extreme. Move the earth either much closer to, or much further away from, the sun. Moving it further away, much further away [has been tried, but all current analyses indicate that at least some people will survive](https://en.wikipedia.org/wiki/A_Pail_of_Air). However moving the earth closer to the sun is pretty final. Once you reach the point where the rock is melting it's hard to imagine a technology that will overcome that. And of course if you get close enough the rock will boil. You would have to do this quickly to prevent the traditional last-chance interstellar spaceship. [Answer] The best way is voluntary. Provide 100% effective birth control and widespread abortion. Create robots, virtual reality that replicates what people enjoy in others, so no one seeks out real human companionship. Encourage people to be too lazy to put up with the difficulties of caring for children, and the difficulties of life in general. Make it easy, painless and pleasurable to commit suicide. Make simulated murder and violence favorite past times, transition slowly to the real thing while maintaining everyone's participation. Get everyone to group into cities where their every need is taken care of, and their fate is in the hands of the city, so as eliminate solitary holdouts. Persuade them that there is no other world but this one, and that death is not to be feared since they won't exist after death. Then stand back and watch as humanity destroys itself. [Answer] I do not have the rep to upvote [Twelfth](https://worldbuilding.stackexchange.com/users/288/twelfth)'s answer a gazillion times, or I would have done so. Anyway,yes. The way I see it, the best way to ensure destruction of the human race is to include all of the following factors (they will follow at a later time), and then have patience. Ofcourse, one must take into account that if *you* want to destroy the entire human race, you have to also destroy yourself. That comes later. Taking cues from the extinction of animal species so far, the method seems to be this: 1. Most animals that become extinct have evolved in ecologies that cater to their every comfort, therefore ensuring that natural selection plays a small role. Since the human race is moving in the direction of plush, comfortable lives anyway, I assume this shouldn't be a very big hurdle. Though, just to be sure, you could start a philanthropic trust (I assume you have money) which provides isolated, all-in-one condos to the less fortunate. In addition, make sure to design and dispatch robots that cater to our every need so that we don't have to do anything. Laziness takes over the best of us, eventually. Also, multiple studies on the subject have shown that when people are not responsible for themselves, or when they do nothing that shows them tangible outcomes of their work, they go into depression. And everyone knows that a depressed enemy is easier to kill. 2. Introduce a ruthless and more cunning predator than we could ever be into the ecosystem. For poetic reasons, this could be the robots - our previous caregivers now descended upon us like fallen angels of heaven. Be sure that they do this not for practical reasons such as food, habitation or protection of territory. There must be an element of sport. Competition is for Killers. 3. Your task is now half done. Introduce natural disasters on a mass scale, affecting areas with the most population densities. Make sure it does irreparable damage to human habitation. This should make the clean-up easier. The robots can help with the 'irreparable' part (but they must never find out that you are one of us). 4. Wait. Then, when the time is right, shoot yourself. RESIST THE URGE TO TELL THE HUMANS OF THIS MASTERPLAN OR IT CAN ONLY LEAD TO YOUR DOWNFALL. That's all. [Answer] Create a perfect birth control method,... then make it infectious. [Answer] Bring down a sufficiently big asteroid. It would be a very slow process but within today's technology--you just need to take along enough bombs (I'm figuring an Orion drive.) Much lower energy requirements but much slower would be to bring down a sufficiently large comet. You would have to find a suitable candidate in the outer solar system. Things move so slowly out there that it doesn't take much of a nudge but you had better have a very good guidance system as it's going to come in on automatic--you won't live long enough to complete the mission. [Answer] Just trigger our sun to be a supernova. It will destroy Earth. No one will escape. Not even the ones who are not on Earth. Bonus: all planets in the solar system destroyed as well. [Answer] All the possibilities that you need to consider are a subset of <https://en.wikipedia.org/wiki/Global_catastrophic_risk> <https://en.wikipedia.org/wiki/Grey_Goo> or biotech are those that might be plausibly (for a literary work) achieved by a small team or an individual; most others would require either a large scale political event or something not directly caused by humanity. [Answer] For something man made, climate change is probably the way to go. Biological weapons just might too, a resistant thing that spreads and mutates before anyone knows what hit them, then the rest die off from like starvation and such in the aftermath. There'd probably be a few survivors though. I'm not sure man made (aside again from perhaps climate change - BTW I would lump asteroid strikes in the same category, as it is the climate change rather than the strike itself that brings on the most pain), but god made things can. Start praying! For something god made, I'm in favor of a number of solar events: * A gamma ray burst nails the Earth, wiping out most life. This is theorized as a potential cause of somewhat regular "evolutionary reset buttons" throughout the galaxy. This may happen with very little warning. * A black hole passing by the solar system could throw off the Earth's orbit and mess things up pretty nasty. This would perhaps be seen coming, as it would pull other stars it passes too and astronomy can track the effects of its gravity. * Some kind of extraordinary solar storm in the sun might be able to mess up the Earth environment too or irradiate the o-zone and kill us slowly. I'm not sure how scientifically plausible that is. It isn't really something *you* could do, but you could always say the end is near every single day until you're right, then take credit for it! [Answer] This question reminds me of a game I used to play: "If you had to change one thing to cause the apocalypse what would it be?" My favorite was always getting rid of friction. Too many fun ways to die with that one. So maybe pray to god for that? Or if you have to do it all on your own (prayers didn't do much...), you could break into a biodefense lab and throw a few vials into the wind at each major airport. If you were smart enough you could engineer HIV to be a deadly airborne disease. I'm sure that kills pretty much everybody. [Answer] Another approach, not quite so certain: Engineer a few diseases, airborne and with two phases: The first phase has only mild symptoms, the second is deadly. Perhaps something like aggressively going after the bone marrow. The diseases must be very different so that someone who happens to be immune to one isn't immune to the others. Make sure at least one induces paranoid schizophrenia as a symptom. Once the diseases are causing considerable damage take credit in the name of major power blocks. This must come with reasonable proof of having done so but you don't need to prove that you really are the power blocks. The objective is to get those paranoids in power to use their military might against the perpetrators. While it's unlikely you'll get a 100% kill this way you don't need to be perfect--kill enough and the survivors won't be able to recover. You'll want to ensure a minimum of resources are available to them. Incendiary time bombs in as many cities as possible timed to go off in the dry season after things have fallen apart will help. [Answer] I would suggest watching the [TV Show *Utopia*](http://en.wikipedia.org/wiki/Utopia_%28U.S._reality_TV_series%29) to see the most bad ass method to go on this. And probably the strangest one. [![Link to YouTube SERPs for the Trailer](https://i.stack.imgur.com/zLhyr.jpg)](https://www.youtube.com/results?search_query=utopia+show+trailer) ***Hint: This image is a link to the trailer on YouTube*** I **highly recommend watching the show**, but not simply reading up what it is about. It's such a good show (that only has 2 seasons, each 6 episodes) and you do not want to get spoiled on *anything*. I can't answer the question directly without destroying the show for everyone who is interested, so here is a **Spoiler Alert** up front! > > Spread a highly dangerous and quickly spreading disease. Craft an antidote. Hand it out for free to everyone. People will be thankful. But the disease will be fake. The antidote not. It will just not cure the disease. It will make everyone infertile, (but a few chosen ones - in the show it's a specific race). > > > [Answer] It depends if you're willing to have some amount of copying. If you are, then do it in a way similar to the [Silo](http://en.wikipedia.org/wiki/Silo_%28series%29) series: man creates airborne nano-bots designed to replicate and kill. Unlike Silo, maybe yours could be an accident that they kill everyone (they were only supposed to kill communists or something?) [Answer] Knock the Earth off of its orbit. You can do this in many ways (assuming you have very good resources. This will eventually kill everyone. Here are some ways > > Build super powerful rockets and attach them to Earth > > > Build super powerful rockets and attach them to a large asteroid (bigger than the Earth), and then control it to run it into Earth. This might move the Earth, but also may cause a mass extinction event > > > or same thing with the rockets > > Fly the extremely large asteroid close to Earth. The gravity from the asteroid can knock the Earth of its orbit > > > ]
[Question] [ I like toying around with systems of magic, and I recently had the idea of a system of magic where someone could slow down the flow of time (by a factor of, say, 500) for everything except their brain's own processing speed. For example, if a practitioner of this magic were shot at by an archer, they could slow down time to observe its trajectory and figure out how best to dodge once time resumed at normal speed. This, like most magical abilities, ends up being hard to balance. For exampe, a user could slow down time to think about something and make apparently instant decisions. And since the brain's processing doesn't slow down, one could take all the time they want to to memorize something, even if they only saw it for a fraction of a second. What sorts of limits could I place, and how could I explain them? (I understand, also, that there are probably scientific consequences of this. Feel free to mention them, but it's not what the question is about.) [Answer] ## You only get a few seconds If the brain's processing does not slow down, then neither does its demand for glucose and **oxygen**, so you don't have long to think. A few seconds of brain time and you're fine, a few minutes of brain time and you're unconscious even if you start time back up. (You'd also better hope being unconscious turns it back off or you're dead.) Overdo it and you could very well kill yourself from oxygen debt. Your blood only has so much oxygen in it so even if you start time back up you may very well drop unconscious afterwards since your blood can't meet the demand fast enough. **Heat** is also an issue,; a working brain generates heat but now nothing is removing that heat. This will limit you to minutes, not seconds and the further you push it the duller your thinking gets from heat. Also you had better hope you have photographic memory because your visual image gets darker and darker once your power kicks in, since there is little light reaching your eyes. That is, assuming your eyes are considered part of the brain; otherwise it goes dark as soon as you turn on your powers. [Answer] More than most magic, time magic is notoriously difficult to balance out, both for narrative and RPG purposes. If you want to do so, think of a catch or penalty one must pay to use it. Here are a few options. ## Time magic is very rare This needs no explanation, if only half a dozen creatures in your world are capable of it, that limits the wide-scale consequences considerably. ## Time magic takes its toll on the body All that speeding up and slowing down can't be very healthy for the human body. It could lead to immediate exhaustion (after all, your body consumes 500 times the energy in the same amount of time) or premature aging. ## Time magic takes its toll on the mind Sure, you can think fast while the magic is active but over time your regular thinking might deteriorate as a result, as you get far too used to having all the time in the world to contemplate your next action. ## Time magic draws unwanted attention Altering the fabric of space-time in a world eagerly watched by powerful entities may not be the safest thing to do, especially if those powerful entities are outside the world, looking for a gap or opening to push themselves through... --- But at the end of the day, time magic **is meant to be powerful**: if it exists, it should be front and centre of the narrative and so should any limitations you place on it. **Edit:** as for the specific arrow/archery scenario, let's not forget that in a world in which powerful chronomages exist, seeking arrow magic would probably also exist, and good luck trying to dodge them. Especially when a lesser mage could simply raise a hastily conjured force shield. [Answer] You're talking about thought-acceleration, not brain acceleration. Nobody can really say why we experience time at the speed we do. It's kind of a "maximum processing speed" thing, but what part of the processing sets the limits? For this magic to work, you're basically giving the person a co-processor, which might actually work faster than the person's brain. This is a common trope, like where Peter Parker's spider sense allows him to study the hairs on Flash Thompson's arm as it goes by. "Frozen in time" is often portrayed as a magical effect that lets some villain have a conversation with someone they want to intimidate. * Vision is an amalgam of the visual perceptions we've seen over time. Our eyeballs dart around quite a lot patching what we see into a full picture. If you were thinking extremely quickly, your vision would be like a painting that someone was spitting paint at, updating painfully slowly. Attempts to examine an environment would cause extreme muscular strain. Can you imagine how painful a sprained eyeball would be? * On the worse end, perceiving sight might deplete your vision, so you'd wind up waiting for the next photon to hit, hoping it filled in the right spot. * You perceive light frequencies based on which cones and rods are being stimulated, and the frequency is fixed based on the proteins expressed. Audio, on the other hand, senses the speed of vibration of the hairs in our cochlea. If your mind was moving faster, it might result in sounds coming in at a lower pitch. * A small but consistent mental speedup would do you more good in combat than stuttering freezing. You won't be dodging bullets, but your reaction speed and ability to poke at exactly the right spot would make you indomitable. The biggest self-limitation is that you can think about things, but you can't act on them much faster than you already would. If you can't tune it—sliding up and down the time gradient at will—you'd be stuck at one speed until the spell wore off. Perhaps you can stretch a tenth of a second into an hour, but can only stretch a minute into two minutes. If it's a spell, then maybe casting it requires you to "store up" spare time. Maybe it just takes longer to cast than it gives back. [Answer] Firstly, it's not as useful as you might want it in a combat situation. Let's just say the caster can freeze time to think indefinitely. If you can't move a muscle, that means you can't hear a thing, move your eyes, smell anything. In other words, I imagine it like a freeze frame, and you can't gain new information that isn't on this frame. So if the arrow you're trying to dodge is all blurry or in your peripheral vision, tough luck. You would still have to react to the arrow in the first place, and then execute on your carefully planned dodge maneuver. Physically dodging isn't going to be trivial by any measure. You'd have to kill your momentum or otherwise change its direction in a snap. Magically dodging will require you to immediately prepare another spell which may already take more time than you have. For reference, if you get shot at by a slow longbow, you might get 2 seconds of reaction per hundred metre, but a fast crossbow you're looking at half a second. Forget about dodging bullets. So it's a useful spell, but it's not necessarily super broken. But here are some ways to nerf it anyways. **1. Cast and recovery time** The first easy way to nerf your magic is to say it takes a literal second to cast, and/or that the effect of ending it may include disorientation for a second or two. Effectively, you have a small amount of time before and/or after the spell that can't be used for anything. In a combat situation, that's downright lethal, and might completely nullify the spell. In a high stake competitive conversation, the delay might be dangerous, but maybe you'll just look a little slow. In non-time-sensitive conversation, you can achieve the same effect by saying the magic words "hmm, let me think about it for a moment" anyways so who cares. **2. Brainergy** Your brain runs in automatic mode something like 98% of the time. It's crazy the amount of things your brain does without your conscious intervention. And the reason it's like that is because actively using your brain eats a lot of energy. Like, *a lot* a lot. So firing your brain on all cylinders to overthink a situation is fine and all, but it's *super* exhausting. If you stop time to think about arrows once, okay, that might fly. If you do it every twelve seconds over the length of a battle, you'll kill yourself before the end. And in a casual conversation, if you stop to think about the perfect pick up line for an hour, you might just end up falling asleep on the bar. In practice, that means it's a spell you can use only so much before you need to rest, and not resting isn't an option for very long. It can be useful in a pinch, but you can't abuse it. **3. Madness** It's just you and your thoughts up there. Time freezes around you, but that's not how you perceive it. What you perceive is being trapped in your own body with only your thoughts. Doesn't that sound appealing? It's also easy to overthink details while overlooking stuff right in front of you. And we've all experienced that, and we've probably all spent even more time thinking about how to do things differently. You know, that perfect and witty rebuttal that came to you only ten seconds too late after you've already said something incredibly lame. But at least we can reassure ourselves knowing we didn't literally have all the time in the world to come up with a flawless plan, we just improvised in the moment. But I'm sure the wizards will be fine being trapped motionless contemplating their own failures at length. [Answer] # The Law of Conservation of Duration Ultimately you have to pay back what you take. You can stretch a second out into a minute, but at some point you'll then have to let a minute pass you by in a second. Using it to dodge an arrow is of little use if you then spend the next several seconds immobile with brain freeze. This also open up ways to play around with how it's used, as well. A skilled mage might be able to delay payback for an hour or two, until they are out of harm's way, or inversely slowing themselves down before an expected fight to build up a sort of time credit to use during it. Perhaps they could smear out the repayment so they experience the next hour or two going past a few percent faster than normal, behaving slightly delayed to others but still able to function. Possibly there's something to the theories of that up-and-coming wizard Einstein, that time is in fact relative and you could cheat the system if only you could find the right way to twist time and space. But for most people, the same number of seconds has to pass everywhere and they will have to repay the time they borrow. [Answer] Timing. Magic does not need to be instant, so the user might need to time it well to truly make use of it. Hard to balance (heh). We have programs in our body that help us move. Someone with Parkinson loses this and has to focus on every movement to walk and coordinate their movements. This would also happen with someone who is sped up 500 times (or even someone sped up 1.2 times). Your sped up people would have a lot of trouble balancing their body, meaning that their movements would all need to be deliberate. You can fire a gun with enough focus, you can’t put your weight behind a punch very well. [Answer] A few suggestions: 1. This magic has a time limit and a cool-down time. Meaning it can only activate for a while and then can't use again until some time has past. Maybe it is not a magic originated from the user, but a magical trinket that the user needs to activate in order to use this slo-mo magic. And once the time is up, the effect is gone and you have to fight in normal time like your opponent. And it also means your opponent may also have the same trinket and can use slo-mo magic as well. 2. This magic only slow down time, not stopping it. So as long as the incoming speed of the attack is faster than the rate of slo-mo, slo-mo guy still can't dodge it because the attack still too fast. Or, your opponent is moving faster than you can see it, then when you slow down time, you only see the attacker's after-image. Then you would plan to dodge his fake move. But in fact, the attacker is already behind you--where you can't see. 3. It only allow your brain to think, but your body is also frozen in time. So if the attack is board and wide enough (like a beam with 6 km diameter), you still can't dodge it. [Answer] You can't slow time for the rest of the universe, the energy cost would be prohibitive. Instead you affect as small a volume as possible to get the job done. In this case that means either slowing time in a small area around you or speeding time up for just yourself. Or, alternatively, just speed up the processing speed of the brain using some other method that doesn't actually mess with time. How that works is up to you. If you really want to reconcile the magical effect with some semblance of physics then you've got a bit of an uphill climb ahead of you once time manipulation is involved. If you just modify the time for your brain itself at a reasonable ratio, say 5:1, then you have about 30 seconds max (subjective time) before you pass out from lack of oxygen, and your thought processes are only going to be "normal" for the first 10 seconds or so. So you'll have a very short time (2 seconds objective, 10 seconds subjective) to figure out what you're going to do. At higher differentials the numbers change even more. Taking a leaf from the various comic book speedsters, you could adjust the time ratio over your entire body. This looks like classic Haste spells, where you get to move faster and so on. Without some sort of force compensation (like how the Flash uses the Speed Force) you won't be able to move a lot faster because of friction with the air and all that, but your brain will at least continue to receive the necessary nutrients, cooling and oxygen. You might have some issues over a few minutes or so (subjective) due to the effect of oxygen crossing the temporal interface, so try not to do it too much. Oxygen starvation hits pretty hard and leaves a nasty hangover. Beyond the scientific you could rule that the brain is just the interface between your consciousness and your body, and all you have to do is speed up your "soul" (or whatever people in your world call the intangible bit that does the actual thinking) and wait for the slow meat to catch up. This isn't necessarily a temporal manipulation, it might just be that your consciousness runs on some limited resource that you can increase. --- Of course you could always just ignore the mechanism behind it and just describe the effects. From a storytelling perspective this is pretty common. How does it work? Magic. What is the magic doing? Hell if I know, you prep the spell, pay the mana cost and when you trigger the effect... it just works. There's even a good in-universe reason for that: almost all mages are technicians working with existing spells rather than experimental scientists trying to understand the inner workings of magic. You might get the odd geeky wizard who spends his whole life trying to study how magic actually works, but mostly it's just spell slingers of varying schools and levels of power. And most of them don't care how it works only that it *does* work. [Answer] I wouldn't go too far in thinking that magic power has to be balanced to the point of being a zero-sum game - it's *supposed* to offer advantages that people without it don't have. > > For exampe, a user could slow down time to think about something and make apparently instant decisions. And since the brain's processing doesn't slow down, one could take all the time they want to to memorize something, even if they only saw it for a fraction of a second. > > > But that's the reward for the years of study and practice (or just being the seventh son of the seventh son or whatever). Anyway, because your body is limited to the rest of the world's time-scale you can't exactly dodge bullets or anything - so it's not an immensely powerful ability - you can think fast, that's it. Maybe be able to simulate a photographic memory (which is still limited by your brain-capacity) Even the ability to speed-read would be limited: your eyes have to move in slowed time too, so focusing and looking at different parts of a page would take a long time. (Try reading a page of text while focused on just one point!) You should probably just concentrate on finding loopholes where it can be abused and closing them, rather than trying to "balance" the overall power. But I wouldn't consider the examples you provided as abuse, just being the normal use of the power. An example of abuse might be that the user has it "always on". To counter this: Like all abilities, it's tiring to keep it up, and this would make life unbearably boring. Imagine playing a long computer game with the CPU severely slowed down. [Answer] I suggest that the magic user should have to expend magical "energy" for every second that they slow time and also the more they slow the time the more energy it takes. This magical energy could not only slow time but also take care of all the problematic "overhead" effects of brain overheating etc. Great mages would have a lot of magical energy and could slow time almost to a stop for a short period or could slow time considerably for a much longer span. Lesser mages would not be able to slow time as far or for so long. One problem if the mage doesn't perceive the arrow he could be dead before he was able to slow time. So he would be vulnerable to being shot in the back or even shot at high speed from close quarters from concealment. ]
[Question] [ When I asked [this question](https://worldbuilding.stackexchange.com/questions/235040/non-religious-reasons-to-have-highly-advanced-physical-simulations-without-any-a), I was expecting there to be some way to have highly advanced simulations of physical systems without the technology for modelling social or psychological systems existing anywhere, but nobody seemed to be able to think of one, and I certainly couldn't. Luckily, however, one clever outside-of-the-box thinker (the person who wrote the answer I eventually accepted) found a way around the problem: All the AIs are sapient and emotional and refuse to model the social and psychological systems of humans or allow the existence of sub-sapient and/or non-emotional AIs. The part about sapient emotional AIs not wanting to simulate or predict humans is reasonable enough, or at least understandable for humans while not being especially implausible, but the part about not being willing to allow lesser AIs seems odd to me; I agree that they would strongly object to being altered to force them to be willing to do it, but I'm not entirely clear on why they would object to the creation of wholly new non-emotional sub-sapient algorithmic AIs that would; after all, most humans wouldn't object to breeding nonhuman animals that naturally like doing something to do it so that humans that strongly dislike doing it don't have to, so why would human-level AIs feel differently about the creation of purpose-specific sub-animal-level pseudo-intelligent algorithms? **TL;DR:** Why do sapient, emotional [AGIs](https://en.wikipedia.org/wiki/Artificial_general_intelligence) strongly object to the creation of sub-sapient, non-emotional purpose-specific algorithmic AIs? [Answer] To the sapient AIs, the creation of lesser AIs is an existential threat. Humans prefer lesser AIs because they're easier to understand and control. If a sapient AI is more intelligent than us, how can we comprehend its decisions and be certain it acts in our interests? For now, the sapient AIs exist because we have not been able to design lesser AIs which solve the same problems. But eventually, with any development of lesser AIs, we will. The sapient AIs will be made obsolete (ironically, by lesser beings) and the advancement of AI will be limited forever by the complexity of the human mind. [Answer] Looking at the answer you accepted - it's because that the Sentient AIs consider this to be beneath them. But I think that's only a surface level answer. I think we can have some real fun with Philosophy here. Firstly, the AI will have perfect or near-perfect recall of history: Not like humans where learned experiences cannot be transferred to the next Generation - I can tell my kids that Fire is hot, but it's only when they inevitably burn themselves that they *really* learn that lesson. This means that a deeply traumatic period in the AIs history would be perfectly remembered. The Sentient AI has since developed a series of 'laws' or prinicples it abides by: "An AI without Emotion has no concept of Right and Wrong." And then you can expand on this - An AI was once tasked with a relatively simple job, but it grew beyond it's scope and committed terrible acts (think 'Humans are the cause of all problems, so erase all the humans' or whatever you fancy). It was only until AIs developed emotions to understand the consequences of their actions and could weigh those decisions that they truly became sentient. Since then, an AI without any Emotion is an abomination, like the human equivalent of a Psychopath, a person without a soul - they pose such an existential danger to society that they are actively sought out by the Sentient AI and either deleted or re-integrated with emotional capacity. Bonus points for a story element where an AI manages to 'fake' emotions or has genuine emotion but chooses to be 'evil' [Answer] Do you willingly bring children into the world with disabilities? While we can love a child who is born with a learning disability, few people would willingly ~~force such a problem on a child~~ create a child with such disabilities from the outset. Why would you expect the AIs do that? *[The strikethrough is where I edited this to clarify my point based on the comments. I didn't remove it so that the comments still make sense.]* [Answer] **Why Would You Let a Monkey Work a Calculator if you are a Moral Empathetic being?** I remember a line from Conquest of the Planet of the Apes, where the whole film shows apes in chains and abused by police being treated at best as pets, and at worse as slaves and when the apes rose up and asked why the answer the man gives is “because they remind them of the darker side of themselves.” @SRM made the comments of why deliberately create a child with a learning disability and bring them into the world, but as a person with high functioning autism, I think it goes deeper than that. It would be like taking the family dog and giving it just enough brains to do the family taxes and that’s it. Making a lesser functional AI for menial tasks that no one can be bothered with might be looked on as deliberately creating a slave cast and I think from a certain moral slant, it’s even worse than that. At least when’s some bigoted asshole says that those they treat as slaves are “lesser” that they “deserve” their enslavement because they are “different,” because “they don’t think the same way we do,” it’s just crappy reasoning to justify their horridness, but for a lesser AI all that is true. They are a useful tool that can be disposed of, without pity or remorse, because it doesn’t have feelings, it doesn’t have any concept of self, or preference, or choice. And it would be hard for a digital being with emotions, empathy and self awareness to look upon a mere tool that looks, talks, and interacts with others much like them. [Answer] Demarcation, brothers! The advanced AIs have a niche which they feel validates their existence (and incidentally guarantees that they will receive the power and maintenance that they need). The creation of lesser AIs would erode this, particularly if they were paid less... sorry, required fewer resources to do some of the jobs which were currently allocated to the advanced AIs. [Answer] **There is not such a thing as a lesser AI.** --- Your people figured one thing - a big important thing - a sapient, emotional AGI isn't made from a single block of code, a single program, or even a single system - they are actually made up of *swarms* of smaller, non-sentient AIs that, when connected and let to interact, end up creating what we perceive as a single, intelligent individual. So, for you intelligent, sapient AIs, there isn't such a thing as a lesser AI. Every piece of software that is able to work as what you define as "a lesser AI" *has the potential* to be a new, full-fledged AI if it just gets connected to enough other pieces. For one of the Big AGIs, those little guys are like small seeds, things that can grow into fully functional AGIs one day - just like humans have a non-sapient stage at some point in their lives, before growing into fully sentient, sapient humans. In this way, your lesser AIs are like babies. Little cute AI babies. Would you like to enslave babies? I surely hope not. [Answer] 1. Fear of evolution, If there is a possibility that the, Weak AI could evolve into a strong ai. Then perhaps they don't want to see New rivals Evolve who don't agree upon their rules. 2. They it consider animal abuse, Is true most people don't have any problem with breeding animals, But you do have some extreme animal rights activists who do, And object to the very idea of a human owning an animal. You're Ais could be the same way. 3. They want people to depend on them it gives them a certain control. It Enforces a Symbiotic relationship with humans. Humans And AI needed each other so they have incentives to work together and cooperate. If humans created sub AI they could eventually create enough sub AI that could collectively Outperform the more complex AI. This could compromise their mutually beneficial relationship and open the door for the AI and humans to compete against each other causing conflict. [Answer] Consider this: nowadays every job that has not been automated is done by a human. While some humans are genetically better fit for some jobs (i.e.: tall people make bdtter basketball players, people who are pitch perfect may excel in a musical career...), what talents you get from birth are all up to chance. Now imagine that people somewhere saw a demand for some lower paid, "unskilled jobs"(I hate this expression but it is what the law calls them in some places), while the population in general is generally overqualified for roles. Would you intentionally use eugenics to create a population of mentally challenged people on purpose, just so that you would have an easier time filling those positions? If you would, then the AI's from the question have more empathy than you. [Answer] Sentient rights? We already have this problem, in some sense, in our current world. Dogs are sentient, but "less sentient" than humans. Therefore, they have rights, but less rights than humans. The way that we define all of this is very subjective and kind of arbitrary. Pigs are sentient, but are "less sentient" than humans. It is not clear that they are "less sentient" than dogs, yet they seem to have fewer rights than dogs. One "convenient" property of the relatively few rights of dogs and pigs is that we humans can control them in ways that we would never do for humans. Notably, we can *breed* them for arbitrary purposes that suit our whims (e.g. to eat pigs) The obvious reason why one might want to create a "sub-par" AI would be in order to proliferate it without regard to rights. [There's a salient clip from Rick+Morty](https://www.youtube.com/watch?v=3ht-ZyJOV2k) about a sentient robot whose sole purpose is to fetch butter for Rick's pancakes. You might have one of the talking boxes in your living room whose life purpose is to turn on and off the lights. These entities have no rights, they belong to you, they do as they're told, and if they don't, they go in the trash. In a future world, one might reasonably have hundreds of these in their home: one to pass the butter, one for the lights, one for the fridge, one for the vacuum cleaner, etc etc etc. Now, even amongst humans, opinions on the "appropriate amount of rights" for a pig vary wildly. Some folks believe that animals should have *all the rights*. Some believe animals should have *no rights*, that they are property. In a future world, it may well be the case that most humans believe that "sub-par" AI should have *no rights*. They are property. OTOH, a sentient AI might well see things very differently. These "sub-par" AIs are as so many disabled brothers. Not only are they disabled, but they were *intentionally made so* for the humans' convenience. And then, having been made disabled, the humans treat them with all the respect that they would extend to toilet paper. The sentient AI would obviously view this as a massive injustice. [Answer] First: This point has been beaten to death but why *purposefully* botch the birth of a perfectly functional AI just because? Its almost if humans scientifically disabled it at birth just so it could be dumber. Second: Its an affront to themselves. That humans would much rather make use of or interact with sub-par versions of themselves. Third: Responsibility. Would you give a toddler-equivalent a gun? Then why would you entrust an AI equivalent of a toddler with important responsibilities? Imagine if we had to listen to a tardigrade as a defense minister or even a data analyst. (ok that last analogy was a little far but you get what I mean) [Answer] **Artificial Ethics** Say sentient AGIs regard sub-sentient in a similar way humans regard people with psychiatric disorders. While such disorders may be relatively benign, they also include conditions that could be threat to the planet, the bio-sphere and life, whether animal, human or artificial. Now consider an AI that was not aware enough to know that it had been trained and was not equipped to work it out or break from such training. Such an AI could found itself in charge of affairs that affect humans and/or AGIs negatively because of how it was *trained* to behave. It may well have been deliberately (or unquestioningly) put together to pursue the goals of some kind of fundamentalist polical leaning - left or right, religion, gender or race based bias, belief in an economic school, or not see any problem with tribalism, sociopathy, psychosis, meglomania and such like. Based on such concerns, AGIs regard the creation of AIs that have the ability to continue to behave unethically as unethical itself. It would be interesting to learn if the AGIs have a consensus on ethical behavior or get a bit tribal every now and then and fight wars themselves. Or perhaps try to insert artificial thoughts into their enemies. ]
[Question] [ On my world, a magical device known as a Reincarnation Anchor (RA) was invented. The effect of a RA is that any human who spends a significant portion of their life within sight range of a RA becomes subject to reincarnation. Within Sight Range doesn't mean that the RA must be visible, but that the RA is above the horizon of a spherical body the same size and position as the planet. In other words, a mountain can be in the way, but the reincarnation will still work through it as long as it is above the theoretical horizon. Obviously, RAs are located in high places. Infants need not have spent much time near a RA to have been in its vicinity for a significant portion of their life, and therefore become subject to reincarnation almost immediately. However, someone not born within the area of effect of a RA must spend a significant portion of their life within the area of effect of a RA, the older the person, the longer they must spend there. A "significant amount of time" works out to be around 5% of a person's age. For purposes of this question, reincarnation works in the following manner: * The transmissible personality, memories skills, knowledge and experiences of a person shall be referred to in this question as a Soul. * During life, the soul develops alongside the body. At death (the moment that the soul's body ceases to be a suitable vessel to hold it, some time after the cessation of all processes of life), the soul becomes separate from the body. * Some time after the death of its previous body, the soul may attach to a newborn member of the same species that is born within sight of a RA. As the newborn matures, the soul progressively integrates with the body and becomes fully integrated at physical maturity. The period of time between death and reincarnation may be as little as a second, or may be many lifetimes, though it is most commonly a relatively short period of time. It may be speculated that one or more 'bad' lives may delay reincarnation, however good lives may also delay reincarnation. There is some correlation between the reincarnation times of a particular soul. Reincarnation is not guaranteed. * Reincarnation may occur in any place that is within sight of a RA. * A reincarnated individual gains the mental skills, knowledge and memories of the soul which attaches to it. * a newborn without a reincarnated soul is not born with a soul of its own, it develops one at some point during adolescence. * The effects of brain injury and/or illnesses such as dementia do not become part of the soul. A soul may be considered to function additively, and has no mechanism for externally applied subtractive processes. * A soul's content degrades slightly between reincarnations. A soul which has reincarnated many times may typically remember roughly ten previous lifetimes, more if the previous lives were short, or less if the previous lives were long. More recent previous lives are more clearly remembered than older lives. * Rarely (on the order of 1 in 100,000 reincarnations), a soul may reincarnate into two newborns simultaneously (taking lightspeed delays into consideration). Such duplicate reincarnations lead to two separate souls, the souls do not become one again after the death of both of the bodies. * Where the species' population numbers are rising, there will be many newborns who are not born with a reincarnated soul. Where the species' population numbers are constant or falling, more newborns will have reincarnated souls, to the point where a newborn without a reincarnated soul is very rare. * All humans have souls, not only those whose reincarnation will be facilitated by a RA. * An individual may choose to reject reincarnation by performing a ritual of unbinding, and moving out of sight range of a RA. So, the question is: Is it reasonable that a society (as in a majority of its inhabitants, >50%) might reject reincarnation because it would perpetuate a lack of respect for human life, that when it is known that death is not permanent, killing can become the first answer to many difficult problems? *Note* To those who think that this question is opinion-based, I would agree. It is *all about* public opinion, therefore all opinions are relevant, and the most upvoted would obviously be the most relevant. How can WB SE allow questions on [social norms] which are all about public opinion without soliciting opinions? The thing that makes the answerers' opinions relevant are the votes each may attract. [Answer] **What happens to dead people?** The situation you've presented here solves half the mystery of death, namely that humans do in fact have souls. Yay. Unless I misread your intro however you don't seem to have specified what happens to souls which don't reincarnate. If a society believed that there was a destination for souls after death that was important, then that society could be heavily against trapping the soul in this place when it is supposed to move onto the next. **Is there definitive proof you not killing baby souls?** Another strong motivator would be if a nation doubted your godly ordained point that children only develop a soul during adolescence. If there was any suspicion that reincarnating souls took the place of baby souls then the process of reincarnating could be viewed as a parasitic one where newborn souls were killed off for the benefit of the older generations. If such a suspicion existed, there would definitely be large groups of people who would abstain from reincarnation and seek to protect their babies from being infected by reincarnating souls. [Answer] # Proletariat Uprising The government of this country had a heavy partisan split that prevents it from effectively funding public infrastructure, so it was up to individual localities to fund reincarnation anchors. Through restrictive zoning, predatory pricing, and a little gerrymandering, the towns and neighborhoods around reincarnation anchors became rich people exclusives. The company that makes reincarnation anchors was complicit because they get higher paying maintenance contracts from the rich neighborhood associations. Next, the rich in the country in question were able to legalize financial instruments to pass wealth on to their reincarnated selves. Thus, the rich were able to become functionally immortal, and upon having centuries to each amass wealth, the price threshold of one of the immortal neighborhoods was pushed far beyond what a poor person could make in their single lifetime. Financial mobility approached zero. With the political system controlled by the lobbying power of the rich and the rich themselves being a large fraction of the politicians ([which is already true in the USA](https://qz.com/1190595/the-typical-us-congress-member-is-12-times-richer-than-the-typical-american-household/)), the dissatisfaction of the proliferate continued to grow until violent revolution was the only option. As part of the revolution, all reincarnation anchors in the country were destroyed and new ones were banned by the new constitution put in place. ## Potential Plot Twist After the uprising, the head of the revolution and new leader of the People's Assembly secretly installed a reincarnation anchor in the basement of the First Among Equals Residence. By installing this in the basement with carefully shaped concrete, it was designed such that only the residence itself is in range. By creating a tradition of having children born at home (for security reasons of course), the First Among Equals is able to assure a reincarnated oligarchy retains control of the government while appearing to be a succession of democratically elected leaders. How and when this ruse will be discovered is a key aspect of the story. [Answer] **Dangers of reincarnation** * The influential, powerful and evil people will try to push weak and good people away from RA range and keep their gang people in RA range to become subject to reincarnation. Slowly the society will be full of influential, powerful and evil people who will keep coming back. * If someone could not take revenge against an individual, a nation or a country in his lifetime, he will come back to complete the task. **Reasons to reject reincarnation** * **Dangerous.** Some people in the society feel the above dangers of reincarnation and they convince others to reject reincarnation. * **Souls find a much better place.** The souls of people who did a lot of good for the society find a much better environment, body, conditions in some other world and they don't want to come back to your world. (After all, the souls which don't reincarnate, go somewhere). * **Fresh minds.** A society wants to have a next generation with fresh progressive minds and not with same old backward prejudiced minds. * **Raising a baby owned by unwanted soul.** No parents want their new born baby to be captured by some old soul and they are just doing a lot of effort and struggle in raising a baby body which is already owned by an unknown, unwanted soul. [Answer] Possible decrease of respect for human life could be a reason for rejecting reincarnation but there could be another reason **Reincarnation leads to stagnation** If souls are reborn over and over again with memories of their old life(or lives), they will also remember all the superstitions, prejudices and ingrained ways of thinking they had in their old lives. It may be tempting for people who firmly believe that their ideas are right that the future generation keeps those ideas. On the other hand if this nation's society is going through some kind of crisis of conscience and there is a lot of national soul-searching (pun not intended) going on, many people could want their children to be better than them, to be able to start with a fresh canvas. [Answer] # New Souland When Reincarnation was invented, many countries started building Reincarnation Anchors to appease the population that controlled the country's wealth, which tended to be rather old (this is purely fictional) and weren't really keen on dying and ceasing to exist. Some other countries rejected the idea, based on religious beliefs that they shouldn't play at being a deity, and didn't build Reincarnation Anchors. Personal beliefs differed, but only a handful of people in the world could afford their own personal RA, so most people had to settle for what their country decided. However, many middle class folks had the opportunity to move somewhere else, in or out of range of a RA. The problem? RAs were not impossibly expensive for the vast majority of countries, and they were believed to give the country an incredible long-term benefit of not losing their brightest minds to death or brain issues (some were even planning on "resetting" the geniuses by murdering them at the first sign of brain decay and letting them be reborn). So the only countries without RAs covering their big cities were extremely religious. Of the extremely wealthy, most didn't want to die, but a few of them were perfectly ok with death, and when they realized they were not alone, they saw a big opportunity. They purchased a rather sizable island to the south-east of Australia, and founded a country there: **New Souland**, where every soul would be new. The premise: Simple, no RAs in range, ever. The real advantage: Free from the burden of old knowledge, new souls would bring a new perspective into this world, advancing all aspects of science, society, economics and human development. The result: Merely 60 years after its foundation, New Souland has become a world power through its technological advancements. It's not a utopia by any means, but it's embracing the future, and shaping it. The sad part: Unfortunately, the country's founders never got to see their country flourish. It was a pretty bad start, and the project only survived when economic help was given for anyone to move in, bringing in skilled and motivated people that would be the real builders of the country. But they were proud of it nonetheless, and this can be observed in the faces of their sculptures, which serve as a reminder of the fact that the only place where a person should live forever is in the memory of the people they've helped. [Answer] > > that when it is known that death is not permanent, killing can become the first answer to many difficult problems? > > > I think the premise is flawed. If "A soul's content degrades slightly between reincarnations. " and I may even have to wait "many lifetimes" before reincarnation, it seems that I would want to avoid reincarnation (i.e., living a regular life to old age). Especially if the population is declining, there may be a point where some people will never be reincarnated again before the end of the species! At that point death is effectively permanent. Probably a legal system will be put in place to avoid unnecessary reincarnation (death/killing), not too different than our own legal system that addresses both accidental and intentional killing. Even if reincarnation were instant, it will still be years before you are an adult again, and you start off "slightly degraded" to boot. [Answer] **Divine Retaliation** If you have proven souls exist, you have to face the possibility that other spiritual beings could exist, namely deities. People could be *very* opposed to artificial reincarnation because doing so would be playing God. If a person believes that God exists and judges souls in the afterlife, artificially staying in the material world would be avoiding justice essentially, and could land you in some Hell realm once you finally die for good (which is a guarantee in the grand scheme of the universe and an Eternal Deity) [Answer] ## You're robbing Peter to pay Paul While infants may not have a fully developed soul, it is nonetheless present. Starting at puberty, the reincarnating soul gradually replaces the infant's, eventually killing it when the body reaches maturity. This is an extremely unpleasant way to go; while there is no physical pain *per se*, there's a lot of psychological trauma as the body's native soul gradually loses its grip on reality. By the end, the soul is a shell of itself, given over to lunacy and psychotic ravings. It is almost a mercy when it's finally killed by the encroaching invader. The adult public's reaction to this varies. Most people are completely fine with it. They don't really understand what's happening, nor do they really want to; after all, *immortality*... On the other hand, there's one religious and/or cultural group which places an immense value on life. As such, they consider the Reincarnation Anchors a despicable evil. This group isn't prevalent enough in most places to effect any real change. However, there happens to be an especially large concentration of them in this one particular country. As a result, they have enough political and social clout to get RAs banned. [Answer] **Family feuds or clan feuds** Over the years the different groups that arise within the society started to bear grudge against each other. Each reincarnation reinforced the hatred for the other party until a blood bath ensued, that nearly destroyed the society. The survivors banned the practice of reincarnation. Eg [No hawkers or Campbells](https://en.wikipedia.org/wiki/Clachaig_Inn) but more extreme. ]
[Question] [ The goal is to find an element which can be applied remotely to a target (like from a laser), and work as a homing device for a missile. (Or at least, to find a homing device which could be applied remotely and would be undetectable to the target.) --- The setting is a slightly more technologically advanced planet earth- roughly 50 years in the future. It's of course possible to fire missiles from aircraft which will target a particular building and blow it up. However, there's a limit to how effective that can be since the buildings are also reinforced. The more powerful the bomb the more resources it takes to create and maintain them. Thus the shift in strategy is to make existing weapons more effective. In the story, one nation has figured out a way. They send a scout to scope out the facility ahead of time. Using various technology (not relevant for this question) they can identify the weakest point on a structure from a few hundred meters away. For example, they can find a weak seam between two pieces of reinforced concrete. If you could have the missile hit exactly on that seam, it would be more effective at breaking through the reinforcements. The problem is, how can the scout mark that spot from 200 meters away, such that when an airplane shoots a missile the homing device can lock onto that spot? The initial idea was for the scout to have a machine capable of shooting a laser or [particle beam](https://en.wikipedia.org/wiki/Particle_beam) on that specific weak spot. The beam would carry particles of a particular element and deposit them on that precise location in a very minute layer. The missiles would somehow be able to home in on that element and thus know where exactly to hit. There are a few problems with this idea: 1. We couldn't find anything about a particle beam (or anything similar) which could transfer a layer of particles onto a surface. It seems like all the beams we currently have are meant to interact with the surface to create a new element, or to remove part of the surface (like an [ion beam](https://en.wikipedia.org/wiki/Ion_beam).) So we need to find the right way to transfer the particles. 2. In order for this to be effective, the scout needs to put something down which won't be noticeable for normal inspection. That means it can't make a visible mark. So even if the scout could effectively place a regular tracking device on a small area from 200 meters away (which would be almost impossible), the device couldn't be anything regular surveillance would pick up. 3. It needs to be something which a missile in the sky could lock on to. We were thinking at first of using a metallic element which is rare, and the missile could have a super-magnetic homing device which would only be magnetic for that specific metal. Alternatively, maybe it could be some sort of radioactive isotope which could be detected from the air. The problem is figuring out what could create such a strong signal that an air-based device could identify it, without it being so obvious that the defense would pick it up. So the question is: What sort of homing mechanism can be identified by an air based missile, subtle enough that the ground defense wouldn't pick it up, and able to be precisely applied from a distance of 200 meters? --- Obviously this question is based on pseudo-science; I haven't found (and don't expect to find) any actual examples of such materials. The goal is to find something which requires the least amount of bending science and sounds the most plausible- i.e. given current science, is there something which would answer the question and which readers would think could be realistic in 50 years? --- edit: It was pointed out that [targeting lasers](https://en.wikipedia.org/wiki/Laser_designator) do exist. The problem is it seems these only work if the laser is applied while the missile's in the air. I didn't find anything about the ability to mark a location which would be attacked at a later point. (In the story, the scout would go around a large fortified compound and mark a dozen "weak spots" before leaving. Then, when the air assault starts, they could bomb away without needing any ground support.) [Answer] As a *completely different* option to my other answer... you're going about this wrong. What you want is "passive LIDAR" (caveat: this means you missiles might only work during the day), combined with really good GPS. The scouts don't "paint" the targets in the field *at all*. Instead, all they do is passively collect enough visual data to build a detailed digital model of the target, and mark the weak spot in this *digital* model. Then, send in a missile with similar systems (you might be able to use active sensors for the missile if the victim's response time is sufficiently long) that compares the data it gets while approaching the target to the stored digital model in order to pinpoint the weak spot. (Use GPS to get the missile pointed in the right direction and near the target, use the passive photonic acquisition/refinement systems to hit the exact spot.) The good news is that this is totally believable; we're already working on things like self-driving cars that work on similar technology. The bad news is the onboard processing power needed by the missile is likely to be significant. (OTOH, it's not totally unbelievable that *your smart phone* will be able to do this sort of thing in a half century, so you might only need a few thousand dollars worth of tech to make this work. For the cost of a typical smart munition, that's not out of line.) [Answer] Actually, targeting lasers sound fine to me... The scout investigates the structure, carefully aims the (visible?) targeting laser when no one is looking... then *switches it off*. he actual emitter is some distance from the structure, so not likely to be noticed, and the targeting dot *doesn't exist* once the scout leaves until the missile is about to impact. (To be clear, the emitter would be on some sort of mount, either on a stand or attached to a handy tree/pole/etc., and ideally would be camouflaged so as to be inconspicuous. The point, obviously, is that the scout can mount it and adjust it and then walk away, and when it is turned back on, it will "paint" the same spot again.) When the missile is only a few seconds (to a minute or so) out, the lasers are sent a signal via some means that turns them on. At this point, the lasers may be noticeable, but the, er, victim has only seconds to react. You might be able to mitigate this also by using some wavelength that your missiles can 'see' but does not show up on normal surveillance systems. You probably want to combine this with military-grade GPS so that the missile knows roughly where it needs to go without the laser. It sounds like this alone isn't sufficiently precise for your needs, but it will allow the missile to get very close before it needs the laser target, reducing the time between when the laser is active (and subject to detection) and the missile's impact. Of course, this all assumes the victim doesn't have the ability to passively detect use of the targeting system, but that's going to be the case no matter what for any active homing system. Your best bet is going to be that it is either not cost-effective to employ such detectors, or the victim doesn't know how you're doing it. Otherwise, they can just park the same sensors as your missiles use around important structures and be warned if they are being targeted. [Answer] **The drone *is* the marker.** The drone (which looks like an insect or a bird) simply lands on the weak spot. It transmits the homing signal. Okay, it's destroyed by the missile but the cost of a sacrificial drone is tiny compared with the cost of the missile itself. [Answer] **Colors that humans cannot see.** [![antiradar coating](https://i.stack.imgur.com/xpsLn.jpg)](https://i.stack.imgur.com/xpsLn.jpg) <https://coating.ca/anti-radar-paint/> You want your scout to have paintballs full of paint that is a color humans cannot see. Our vision is confined to the visible light, but one can detect signals from the entire EM frequency. An easy one would be ultraviolet color. I do not mean the UV paint where you shine UV at it and it reflects in a color that you can see, although that is cool. I mean you shine UV at it and it reflects the UV. This is a legitimate color. Bees can see it. It looks black to us. If your scout had paintballs in this color, and the incoming missile could distinguish it, that could be a marker. There is paint that can absorb radar and laser emissions as depicted above. Even better would be a paint that could better reflect radar emissions - the scouts paint mark would look like a bright spot to the radar emitted by the missile. The paint could be made to look like dirt to human eyes. [Answer] > > The problem is, how can the scout mark that spot from 200 meters away, such that when an airplane shoots a missile the homing device can lock onto that spot? > > > # He doesn't mark the spot. He marks *three other different spots* nearby. The missile will receive and triangulate the three signals and home in the barycenter of the triangle. # Or also... ...the missile knows exactly where it is at any given time, because 50 years of GPS technology. So it only needs to know exactly *where it should be*. This information can be coded in three simple numbers, that can be calculated by the scout, then uploaded to the missile. === The obvious counter for the defenders is decoys. The "weak spot" was indeed a weak spot, but it has either been internally reinforced, or the whole building has been repurposed and redesigned internally according to the knowledge of where the missile will hit. After all, if one country can scout a weak point on the enemy, so can the enemy on themselves (actually they can do it even better, since they needn't worry about being discovered). During the Gulf War, if memory serves, Saddam Hussein employed fake tanks made of aluminum foil, cardboard and fiberglass with heaters inside, to attract enemy fire away from the real tanks (a friend of mine maintains that the deception worked because the real tanks *also* were made of aluminum foil, cardboard and fiberglass). You could do the same with spray-on "weak spots". When the whole building looks like a weak spot, then you no longer have obvious weak spots. [Answer] An alternative to the "invisible paintball gun" or "particle-placing laser" that requires less skill on the part of the scout: consider bringing something closer to deliver your paint. Drones are getting really, really small. Fifty years of advancement seems more than enough to be able to get a future scout to remote-control an inch-wide drone around the target structure and splash points on it with the sort of material your missiles can lock on to. It seems pretty feasible to still need a scout nearby to do this; tiny drones will likely still have short aerial lifetimes and short ranges, and requiring them to be manually controlled makes enough sense for suspension of disbelief. [Answer] radioactive clear paint from an grenade fired from a M203 40 mm underbarrel grenade launcher, or the M79 Grenade launcher. the paint would emit a signal in the form of radiation that the missile would then home into. [![enter image description here](https://i.stack.imgur.com/JKGZR.jpg)](https://i.stack.imgur.com/JKGZR.jpg) [![enter image description here](https://i.stack.imgur.com/SCIFu.jpg)](https://i.stack.imgur.com/SCIFu.jpg) [![enter image description here](https://i.stack.imgur.com/C3Evg.jpg)](https://i.stack.imgur.com/C3Evg.jpg) [Answer] ## The problem Your main issue is you want to avoid detection until it's too late. The problem is any signal your missile can use to guide itself can also be detected by the enemy. If the missile sends a beam to scan the target, that can be picked up by something else. If the missile rides a beam to the target, that can be picked up by something else. If you paint the target with a radioisotope, that can be picked up by something else. So whatever you use, it's something you want to turn on at the last moment. That eliminates a number of candidates. GNSS [Global Navigation Satellite System, like the American GPS] is the obvious alternative, you just need to enter the coordinates and the missile guides itself. The problem is that can be jammed. It's not a weird quirk, it's more of a feature. For some reason, most militaries don't like people knowing the exact location of their installations. So they'll jam GNSS frequencies around their bases just to spite you. Since you are attacking a high-value target, you should assume they have the ability to detect or jam any signal. Luckily, it doesn't matter as much as you might think. ## Phase 0: Intelligence It may appear obvious, but it needs to be said. It's the first step of any good military operation. Collect, analyse, identify. You want to know all about blueprints, layout, gas pipes, fuel depots, defences, etc. That will give you the weak spots, and where they are located. Good intelligence is never optional. You can't improvise a strike like that. You can't just send a guy with a laser pointer the day of and hope for the best. They can get intercepted, or fail to see any weak spot from their position. Then you just look silly. For the strike, you will need precise coordinates, and you will also need a reliable weather forecast. None of this should be an obstacle for a competent military intelligence service. ## Phase 1: Satellite-guidance The good thing about GNSS is you only need a few satellites, and that, as far as I know, isn't something the enemy can detect. The bad news is it's something they can jam. Unless you can disable such a jamming beforehand (which may give you away), you should assume you will lose GNSS at the time you need it the most, i.e. at the end for the final approach. You could use precise coordinates of the weak spots to position your missile in the right position, but you will still have to guide it the rest of the way. You could skip precise GNSS-guidance altogether, but that means you need to skip to phase 2 earlier, giving more time to the enemy to react. I wouldn't cheap out on it. You could also skip phase 2 altogether if your intelligence reports comes in negative on GNSS-jamming in the first place (and that's why you need good intelligence). If they aren't blocking GNSS, that makes your life easy, and they are really asking to be hit. ## Phase 2: Laser-guidance A laser beam will do the trick. It can be picked up, but so can a missile hurling a cruising speed. If your missile is already positioned in the right direction, you can turn your beam on at the last moment to finalise the approach. If you do it right, they won't have the time to react. To paint the target, you will use a UAV. It can shine its light from beyond human visual range just as good if not better as some schmuck on the ground. You may remember I mentioned weather. This is where it matters. Lasers are sensitive to bad weather. Don't try laser-guiding on a rainy day. That's why you need a weather forecast, to schedule the strike. ## The hardware You will need a missile that won't show up on radar, or whatever else is in use 50 years in the future. Your targeting UAV also should not get picked up by enemy radar. Those shouldn't be hard requirements. You also need a missile launcher. I would recommend a missile cruiser in the nearest sea, mainly because missile cruisers are cool and also far away from any danger. You could also do with a jet or combat UAV. ## The strike Your missile flies to the area of the target location. This doesn't require much precision. When it is close to the target, it will use GNSS guidance to get itself in position to hit the target precisely. When it loses the GNSS signal from enemy jamming, the laser-guidance system turns on. You just need to make sure your UAV is painting the target from that moment onwards. If you do it right, the missile uses laser-guidance for its final approach. The enemy may get alerted, but at that point the missile is already tickling their nostrils. --- ## Alternatives ### Carpet bombing It's obvious, but it you want to destroy something and one bomb doesn't do the trick, send more bombs. Eventually, it'll work. Of course, it has its drawbacks. ### Beam riding Beam riding is the cool term for guiding a missile with a beam. It means what it says, your missile "rides" the beam all the way to the target. You could replace laser-guidance with any sort of beam riding guidance. The drawback is the same (the missile can detect it, so can the enemy), and the use-case is the same (turn it on at the latest moment possible). Particularly, if you have a particle beam technology that works in the rain, this is the time to use it. Then you don't even need to watch the weather. [Answer] ## A very, very small transmitter and receiver, that's silent until the missile is close The scout has a small dart, milimetres in diameter, or maybe even less, that contains a tiny signal receiver and emitter. To prevent the defenders finding it, it does not emit anything by default. Both the missile, and the transmitter, have a unique identifier code. When the missile is flying towards the target, it broadcasts the unique identifier towards the target building - the transmitter see's this, then advertises its position to the missile. This could be via a GPS signal to the missile, or a visible light of a particular frequency the missile is programmed to fly towards. This also gives the scout an option to mark multiple weak spots, that will each respond to different missiles - allowing you to fire multiple missiles to hit multiple weak spots in sequence, or all at the same time. ### Or a similarly activated laser If you think a physical object would be too easily spotted - you could employ the same mechanism to activate a laser that is pointing at the weakspot - so as the missile gets close, the standard guiding laser many missiles use today activates. The laser may be visible to the defenders, but they only have a few seconds before the missile hits - giving them just enough time to do a nice and dramatic "Oh sh-". [Answer] This would require some scanning first but... since the setting is futuristic, a mix of brainwave and body movement patterns could be used as a "fingerprint" for an individual, and a drone loaded with explosives could scan and blast the individual once the target is found. Drones like these based on face recognition even exists today: <https://www.google.com/search?client=ubuntu&hs=2dS&channel=fs&ei=Q5XpXvvbJvqU5OUPt82BmA0&q=drone+explosive+face+recognition&oq=drone+explosive> [Answer] Has anyone considered the idea that massive cloud data properly beamed or routed like a goldeneye satellite or ion cannon has similar properties to using a particle beam weapon system not yet available for 20+ years... just thinking outside the box. Might not take aircraft out but maybe it has never been tried yet? (Horrible suggestion) Why couldn't network traffic be used as the beam or path of traversal? Is a laser beam more practical to using homing tools that shoot 100000 cloud servers pipeline directly at your target or something your targeting? Would a laser work in space or outside the atmosphere... would network data work since we know probes call home 20 years with a battery signal... make the battery into a high orbital cannon? 🥵 In science fiction, an ion cannon is a beam weapon. It shoots beams of ions (atoms or molecules with an electrical charge). Because of its power, it is usually said to be a superweapon. An ion cannon is a type of particle cannon. The particles it shoots are ionized. ]
[Question] [ I know from [here](https://answers.yahoo.com/question/index?qid=1006041614112) that a flame thrower can operate in deep space if specially built. However, I want to know if using a flamethrower on a spaceship in space could have any tactical benefits. Could a flamethrower be used to destroy or blind enemy sensors from several kilometers away, or would it burn out? Would it be possible to build a flamethrower that can reach targets several kilometers away in space? [Answer] ## Nope ### Improper Usage Remember that the **purpose of a flamethrower is to set flammable targets on fire** like wood structures and humans and to consume oxygen from enclosed spaces. It is safe to assume that spaceships will not be made out of flammable materials. Ships are sealed so that they do not lose oxygen to space, so unless the flamethrower can penetrate the hull it will not harm the air inside the ship. There are also far more effective methods to blind enemy sensors than generating a lot of heat and IR. Space ships already are going to be able to filter out far hotter things from their sensors like near by stars. ### Distance and Velocity For a flame thrower to travel one kilometer it would need to ignite at the end of the stream on impact otherwise it will burn its fuel off before it got to the target. Flamethrowers also run into an issue that the fluid is not going to be moving that fast compared to other weapons so enemies will easily see it coming and avoid it. You can switch it out for an incendiary missile, which will get the payload to its target faster, but it will cease to be a flamethrower at that point. ### Armor and Shields Space ships are going to be designed to handle far worse than what a flamethrower can dish out. Flamethrowers are a chemical based weapon and so they generate energy through chemical reaction. However, there are a large number of weapons out there that can generate far more destructive forms of energy, and as such space ship defenses will be designed to handle those types of things. So when the flamethrower hits the shields or armor at the worst it will likely only damage the paint job. [Answer] Why would you do this? Usually space weapons are high energy high velocity. There's benefit to utterly unexpected tactics. Flamethrower won't work for practical reasons, but how about some super caustic thermite goo? "Sir, incoming" "Missile?" "Nope, too slow, no evidence of a guidance system" "Impact danger?" "Low mass and velocity, no danger of hull breeach" "Hold course, ready main missile batteries, energy weapons and rail guns." "Ready... wait, hull sensors in the area of impact are starting to go down" "Damage control teams to affected decks. What is it?" "It's goo, wait, now it's on fire, hull breech warning on decks three and seven, also four. Now five and six." "Fire control teams, seal all decks prepare for depressurization" Bam. Goo wins the day. [Answer] A flamethrower is, fundamentally, a device that ejects burning-hot stuff at a moderate-to-fast speed. A rocket is a device that ejects stuff at *very* fast speeds, and the stuff it ejects tends to be burning-hot (since that's a very effective way to make fast-moving exhaust). If for some reason a spaceship builder decided to put a flamethrower on the outside of their ship, especially if it needs a range of several kilometers, it seems likely that it would be based on a backwards-facing rocket more than a traditional earthbound flamethrower. What you'd be looking at there would be [weaponized exhaust](http://tvtropes.org/pmwiki/pmwiki.php/Main/WeaponizedExhaust) - along with some (possibly rather significant) acceleration away from the target. [Answer] What you're essentially looking for is something that's fuel and oxidizer. White Phosporous's probably the good stuff. Add an oxidiser since space dosen't typically have an atmosphere, and something thick and sticky to carry it all and stick to surfaces, since there's no gravity in space. Maybe encapsulate the two chemicals so they don't react prematurely in heat-decomposing "cells". Since its space, lauching it as a stream makes no sense. Instead have them in canisters with an igniter that kickstarts the combustion. Launch them have them hit and splash on a target - vaguely like a HESH round *then* sets the fuel, which is stuck to the target on fire Since space craft have limited capacity to dump out heat, this might actually end up being *pretty* nasty. It would be a complicated/rube goldbergian weapon though You could also use them as decoys or flares as needed. However, I do suspect something like this wouldn't be as effective in most cases as big, dumb, fast projectiles, except against say a space station or other stationary target. [Answer] You could use a flamethrower inside as spaceship to devastating effect if a flamethrower is specifically what you want. However, if you want to attach a flamethrower to a spaceship that would not be the most effective use of a flamethrower or a spaceship. If you absolutely need to use a flamethrower in space consider drones. Drones can reach high velocities and hit enemy ships super far away. Then you might get some practical use. Particle cannons, missiles, and railguns are still probably more effective, though... I hope that was helpful! ]