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[Question]
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Previous parts here:
[Creating a scientificly semi-valid super-soldier, part 1: Skeleton](https://worldbuilding.stackexchange.com/questions/106292/creating-a-scientificly-semi-valid-super-soldier-part-1-skeleton)
[Creating a scientificly semi-valid super-soldier, part 2: nervous system](https://worldbuilding.stackexchange.com/questions/107365/creating-a-scientificly-semi-valid-super-soldier-part-2-nervous-system)
[Creating a scientificly semi-valid super-soldier, part 3: Physical shock resistance](https://worldbuilding.stackexchange.com/questions/107635/creating-a-scientificly-semi-valid-super-soldier-part-3-physical-shock-resista)
After running a mile or fighting through fifty bad guys it's a rare sight to see a hero or villain be panting exhaustedly. In fact, the more capable and genetically altered they are the less oxygen they seem to need instead of more.
So how could you design a (preferably humanoid) creature with improved lungs? The main focus of the question lies on getting as much oxygen volume into your blood as possible per unit of time, but things like lung tissue capable of withstanding violent shocks without rupturing are welcome idea's as well.
Keep in mind: In our current lungs there's no "wind" in the respiratory lobules. The passage of air into them happens purely on diffusion. Additionally, we don't want lungs that will cause our super-creature to be easily susceptible to dust, viruses, bacteria and fungi that are in the air and can clog up or infect the lungs.
[Answer]
I've already asked two question in this site that maybe could help you in order to make your super soldier, also, I'll explain them and try to produce more ideas:
1. [How to increase the efficiency of lungs](https://worldbuilding.stackexchange.com/q/85694/35041);
* There [JDługosz♦](https://worldbuilding.stackexchange.com/a/85695/35041) made a very interesting answer proposing the [bird respiratory system](https://en.wikipedia.org/wiki/Bird_anatomy#Respiratory_system).
* Also, [Aaron Barnard](https://worldbuilding.stackexchange.com/a/85814/35041) proposed a slighly change in their biochemistry.
2. [How to make a human that doesn't need breath](https://worldbuilding.stackexchange.com/q/98391/35041);
* [P Chapman](https://worldbuilding.stackexchange.com/a/98442/35041) and [elemtilas](https://worldbuilding.stackexchange.com/a/98392/35041) proposed an increase of myogoblin.
# [Bird respiratory system](https://en.wikipedia.org/wiki/Respiratory_system#Birds)
**P.S:** if you or someone decide to give me an upvote for this, instead give that to [JDługosz♦](https://worldbuilding.stackexchange.com/a/85695/35041).
[](https://i.stack.imgur.com/Rsa6k.jpg)
From [Wikipedia](https://en.wikipedia.org/wiki/Respiratory_system#Birds):
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> The cross-current respiratory gas exchanger in the lungs of birds. Air is forced from the air sacs unidirectionally (from right to left in the diagram) through the parabronchi. The pulmonary capillaries surround the parabronchi in the manner shown (blood flowing from below the parabronchus to above it in the diagram). Blood or air with a high oxygen content is shown in red; oxygen-poor air or blood is shown in various shades of purple-blue.
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This respiratory system let birds to simulate and inhale and exhale at the same time, "basically doubling" (don't exactly) the amount of air absorbed. They have air sacs: while they inhale, the 50% of air goes to some air sacs with O2, and the another 50% is consumed and stored as CO2 in another sacs, during exhalation, the 50% of O2 in air sacs is consumed and expelled, while at the same time the 50% of C02 in air sacs is just exhaled (they are able to get oxygen even when they are exhaling, thing that we can't do).
* If you don't understand how it works, read the wikipedia's link, in this diagram wasn't show but birds also have air sacs to store air. If you keep without understanding, ask me in comments and I will try to help you. It took me a while to also understand it :).
* This system is more vulnerable to CO2 inhalation (breath faster the toxic -> die faster), also is more vulnerable to hold breath.
+ Maybe they may have a hybrid mammal and bird respiratory system. Like a smaller lung, or adapted air sacs in order to also be able to absorb the storaged oxygen.
# Hemogoblin, myoglobin and (2,3-BPG)
**P.S:** if you or someone decide to give me an upvote for this, instead you should consider give it to [Aaron Barnard](https://worldbuilding.stackexchange.com/a/85814/35041), [P Chapman](https://worldbuilding.stackexchange.com/a/98442/35041) and/or [elemtilas](https://worldbuilding.stackexchange.com/a/98392/35041).
Futhemorer do anatomical changes we can also do some microscopic but not less important adaptations.
### [**Hemogoblin:**](https://en.wikipedia.org/wiki/Hemoglobin)
I am quite sure you have heard at least one time in school about this protein, it transports oxygen from the lungs to the body cells, and also transport the carbon dioxide from the body cells to the lung. Actually, people who live in high altitudes (like mountains with low oxygen) or people who smoke have an increase of this compound in their blood (red blood cells), as a response from the body to a decrease of oxygen intake: **the body increase the absorbtion efficiency**. You soldiers could have a higher concetration on this in blood.
### [**Myoglobin:**](https://en.wikipedia.org/wiki/Myoglobin)
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> High concentrations of myoglobin in muscle cells allow organisms to **hold their breath for a longer period of time**. Diving mammals such as whales and seals have muscles with particularly high abundance of myoglobin. Myoglobin is found in Type I muscle, Type II A and Type II B, but most texts consider myoglobin not to be found in [smooth muscle](https://en.wikipedia.org/wiki/Smooth_muscle_tissue).
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### [**2,3-Bisphosphoglyceric acid:**](https://en.wikipedia.org/wiki/2,3-Bisphosphoglyceric_acid)
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> 2,3-BPG is present in human red blood cells (RBC; erythrocyte) at approximately 5 mmol/L. It binds with **greater affinity to deoxygenated hemoglobin** (e.g. when the red blood cell is near respiring tissue) than it does to oxygenated hemoglobin (e.g., in the lungs) due to spatial changes: 2,3-BPG (with an estimated size of about 9 angstroms) fits in the deoxygenated hemoglobin configuration (11 angstroms), but not as well in the oxygenated (5 angstroms). It interacts with deoxygenated hemoglobin beta subunits by **decreasing their affinity for oxygen**, so it allosterically **promotes the release of the remaining oxygen molecules bound to the hemoglobin**, thus **enhancing the ability of RBCs to release oxygen near tissues that need it most**. 2,3-BPG is thus an allosteric effector.
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Emphasis mine of both quotes. Quotes from Wikipedia.
Great! Right? Well, it's quite difficult to understand, it took me around a while to understand well how it works exactly when Aaron Barnard posts it.
In other words, 2-3BPG has an affinity to red blood cell with a low amount of oxygen in their hemoglobin because they are near muscles and are releasing it. When this chemical combine with hemoglobin it decreases the affinity (ability to retain) oxygen, releasing it even faster to the muscles; oxygenating tissues and being able quicker to travel to lungs in order to re-oxygenate.
Actually, people who live in higher places have an increase in this chemical. 2,3-BPG helps the body to resist [hypoxia](https://en.wikipedia.org/wiki/Hypoxia_(medical)) and other oxygen privation situation or diseases.
Also, remember that create 2,3-BPG consume energy (which can be used in muscles):
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> There is a delicate balance between the need to generate ATP to support energy requirements for cell metabolism and the need to maintain appropriate oxygenation/deoxygenation status of hemoglobin. This balance is maintained by isomerisation of 1,3-BPG to 2,3-BPG, which enhances the deoxygenation of hemoglobin. Low pH activates the activity of biphosphoglyceromutase and inhibits bisphosphoglyerate phosphatase, which leads to increases in 2,3-BPG.
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[](https://i.stack.imgur.com/MB2hm.png)
And:
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> Like hemoglobin, *myoglobin is a cytoplasmic protein that binds oxygen on a heme group*. It harbors only one heme group, whereas hemoglobin has four. Although its heme group is identical to those in Hb, **Mb has a higher affinity for oxygen than does hemoglobin**. This difference is related to its different role: whereas hemoglobin **transports** oxygen, myoglobin's function is to **store** oxygen [generally in muscles].
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Emphasis (bold and itallic) and square brackets mine. Quotes from Wikipedia.
# Better Spleen
I have read somewhere [citation needed :(, I think wikipedia] that exist some drugs that gives us the innate ability of some mammals: increase amount of blood cells during excercise activities (the spleen in some animals -very little in humans- has the ability to store red blood cells and produce them [we lose that ability after born]) but in humans it could produce heart problems because our heat can't beat with a denser blood, we need an stronger one.
# [Myocyte](https://en.wikipedia.org/wiki/Myocyte#Fiber_types) (AKA: muscle cells)
An introduction from Wikipedia:
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> A myocyte (also known as a muscle cell) is the type of cell found in muscle tissue. Myocytes are long, tubular cells that develop from myoblasts to form muscles in a process known as myogenesis. There are various specialized forms of myocytes: cardiac, skeletal, and smooth muscle cells, with various properties. The striated cells of cardiac and skeletal muscles are referred to as muscle fibers.[3](https://i.stack.imgur.com/xf972.gif) Cardiomyocytes are the muscle fibres that form the chambers of the heart, and have a single central nucleus.[4](https://i.stack.imgur.com/k0Xxr.png) Skeletal muscle fibers help support and move the body and tend to have peripheral nuclei.[5][6] Smooth muscle cells control involuntary movements such as the peristalsis contractions in the oesophagus and stomach.
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In [this link](https://en.wikipedia.org/wiki/Myocyte#Fiber_typing) you will find a bit below a large table that explains the difference between 3 types of muscle cells. Each type of muscle cell has different characteristics, **I am not a medic** but after reading a bit I get to the conclusion that:
* **Type I fibers** (Slow Oxidative (SO)) are basically "slow" muscles... they consume less oxygen and can work without getting tired **a lot** more time, but they are weaker and slower.
* **Type IIA fibers** (Fast Oxidative/Glycolytic (FOG)) are "intermediate/fast" muscles: they consume more oxygen, are faster, a bit more stronger and can resist quite well fatigue, but not for an unlimited time (they have fewer capillaries density so I guess they resupply oxygen slower, but they store some energy inside).
* **Type IIX fibers** (Fast Glycolytic (FG)) are "fast and strong" muscle cells: they are fast and the strongest ones, but they lack of fatigue resistance and store a lot less oxygen and energy inside them.
Don't worry! You don't have to choose only one type of fiber! Muscles are made by a composition of X% type I, Y% type IIA and Z% of IIX, so you could archive the best combination of durability and force/speed for each muscle in their bodies!
Also, I think that people which trains doing exercise can increase the amount slow-tissue-slow-oxygen-consumption up to 90%. In [this link](https://es.wikipedia.org/wiki/Monodon_monoceros#Buceo) about the Narwhal there is a comparison with Narwhal muscles and marathon people.
# Blood circulation on tissues regulation
The [Narwhal](https://en.wikipedia.org/wiki/Narwhal) is a marine animal able to dive really deep (record of 1.864 metres below water) during a decent amount of time (30 minutes normally, and up to 3 hours during winter).
They are able to do this thanks to this characteristics:
* They have a high amount of myoglobin in their muscles. (Talked above about it).
* During hypoxia situation it's able to priorize the blood flow only to vital organs as brain, lungs and kidneys, reducing it oxygen consumption (non-vital organs reduce their consumption) and priorizing it to better places.
* Oposite as Dolphins, they don't have "fast-muscles", instead they use slow contraction muscles (also know as "red muscle") (87% instead of 40-50%). (Talked above about it). This kind of muscle consume less oxygen and is highly ressistent fatigue.
# [Lactic acid fermentation](https://en.wikipedia.org/wiki/Lactic_acid_fermentation)
I found a better explanation in the Spanish link of Wikipedia so I'll try to do my best to translate it:
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> Lactic fermentation is done on muscular tissue when there is an intense anaerobic exercise, in other words, there isn't enough oxygen supply to muscles in order to perform aerobic respiration.
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> When lactic acid is acumulated on muscular cells it produce symptoms of muscular fatigue. Some cells, like eritrocites (red blood cells) hasn't mitochondrias so they are forced to get energy using lactic fermentation. On the contrary, the parenchyma die quickly because it doesn't do fermentation, and it only energy source is aerobic respiration.
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In other words, when there isn't enough oxygen in your body, your muscular cells switch to an anaerobic respiration: lactic fermentation. The problem is that the lactic acid... is acid, and your body doesn't like acid ([acidosis](https://en.wikipedia.org/wiki/Acidosis)). So your cells try to expulse that acid and send it to the bloodstream, the problem is that our cells aren't able to expulse it with enough fast, and it acumulate inside them, producing pain. Your super soldiers could have better bodies modified to be able to use it more frequently without problems.
I won't explain the [citric acid cycle](https://en.wikipedia.org/wiki/Citric_acid_cycle) nor this one (because I am not a biologist and they are too large), but I'll try to give basic explanation to you:
* [**Glycolysis:**](https://en.wikipedia.org/wiki/Glycolysis) **1 Glucose** + **2 ATP** + 2 ADP + 2 P + 2 NAD+ → **2 [pyruvate](https://en.wikipedia.org/wiki/Pyruvate_dehydrogenase)** + **4 ATP** + 2 NADH + 2H+ + 2 H2O
* **1 Pyruvate** + 1 NAD+ + CoA → **1 Acetyl-CoA** + NADH + CO2 + H+
+ [**Citric Acid Cycle:**](https://en.wikipedia.org/wiki/Citric_acid_cycle) **1 Acetil-CoA** + 3 NAD+ + FAD + GDP + Pi + 2 H2O → CoA-SH + 3 (NADH + H+) + FADH2 + GTP + 2 CO2
- Several more steps (8?) with GTP and NADH (also with FADH2?) → **TOTAL NET** → **29.85 ATP** to **30 ATP**, with a theorical max of **36 ATP**. (Biology isn't exactly, it's random).
* [Lactic acid fermentation](https://en.wikipedia.org/wiki/Lactic_acid_fermentation) **1 Pyruvate** + NADH → **Lactic acid** + NAD+ + **2 ATP**
+ So 2 ATP from Glycolysis + 2 ATP from Lactic fermentation → 4 ATP instead of around 29.85 - 30 ATP. **Obviously Krebs Cycle (citric acid cycle) is better, but it needs oxygen, that is why our body only use it on emergency (low O2)**, your soldiers will need to eat more calories due to the low efficiency of fermentation.Looks this cute lactic acid fermentation animation:
[](https://i.stack.imgur.com/xf972.gif)
**Edit:** [@Demigan](https://worldbuilding.stackexchange.com/users/48354/demigan) pointed in comments:
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> FYI, lactic acid does not damage the cells. It has long been thought so as whenever lactic acid was present so did muscle pains, but tests showed that your cells suffer no ill effects from the lactic acid, it just happens to coincide with the work you did and because of that the amount of pain you might experience. Unfortunately, it's rather hard changing something relatively minor that is being used in textbooks and sports everywhere.
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So I have read a bit more and I found also something similar, I put a quote because I didn't understand it enough in order to take my own conclusions:
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> In 2004 Robergs et al. maintained that lactic acidosis during exercise is a "construct" or myth, pointing out that part of the H+ comes from ATP hydrolysis (ATP4- + H2O → ADP3- + HPO2-4 + H+), and that reducing pyruvate to lactate (pyruvate- + NADH + H+ → lactate- + NAD+) actually consumes H+. Lindinger et al. countered that they had ignored the causative factors of the increase in [H+]. After all, the production of lactate- from a neutral molecule must increase [H+] to maintain electroneutrality. The point of Robergs's paper, however, was that lactate- is produced from pyruvate-, which has the same charge. It is pyruvate- production from neutral glucose that generates H+:
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+ Glucose + 2 NAD+ + 2 ADP3- + 2 HPO2-4 → 2 pyruvate- + 2 H+ + 2 NADH + 2 ATP4- + 2 H2OSubsequent lactate− production absorbs these protons:
+ 2 pyruvate- + 2 H+ + 2 NADH → 2 lactate ion- + 2 NAD+Overall:
+ Glucose + 2 NAD+ + 2 ADP3- + 2 HPO2−4 → 2 pyruvate- + 2 H+ + 2 NADH + 2 ATP4− + 2 H2O → 2 lactic ion− + 2 NAD+ + 2 ATP4− + 2 H2OAlthough the reaction glucose → 2 lactate- + 2 H+ releases two H+ when viewed on its own, the H+ are absorbed in the production of ATP. On the other hand, the absorbed acidity is released during subsequent hydrolysis of ATP: ATP4− + H2O → ADP3− + HPO2−4 + H+. So once the use of the ATP is included, the overall reaction is:
+ Glucose → 2 pyruvate- + 2 H+The generation of CO2 during respiration also causes an increase in [H+].
Quote from [Wikipedia](https://en.wikipedia.org/wiki/Lactic_acid#Exercise_and_lactate). I've replaced some complex chemical formulas to its chemical names.
# [Cori cycle](https://en.wikipedia.org/wiki/Cori_cycle)
Did you still remember all that I've said about the lactic acid fermentation, this is why I was talking about it:
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> The Cori cycle (also known as the Lactic acid cycle) [...] refers to the metabolic pathway in which lactate produced by anaerobic glycolysis in the muscles moves to the liver and is converted to glucose, which then returns to the muscles and is metabolized back to lactate.
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Our muscles cells are too focused on "being" muscles and so they aren't able to get energy efficiently and quickly, so they centralized part of this task to the liver.
Basically our muscles consumes glucose and produces lactic acid, which is send to the liver and is returned into glucose (with a slightly net energy loss) in order to be re-sent to muscles again.
[](https://i.stack.imgur.com/k0Xxr.png)
If you don't understand this picture you can go to the Spanish Wikipedia, they have a more colorful version of it :) (If you want I can edit it with paint).
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> Muscular activity **requires ATP**, which is provided by the **breakdown of [glycogen](https://en.wikipedia.org/wiki/Glycogen) in the skeletal muscles**. The breakdown of glycogen, a process is known as [glycogenolysis](https://en.wikipedia.org/wiki/Glycogenolysis), releases glucose in the form of glucose-1-phosphate (G-1-P). The G-1-P is converted to G-6-P by the enzyme phosphoglucomutase. **G-6-P is readily fed into glycolysis**, [...] a process that provides ATP to the muscle cells as an **energy source**. During a muscular activity, the store of ATP needs to be constantly **replenished**. When the supply of oxygen is sufficient, this energy comes from feeding pyruvate, one product of glycolysis, into the Krebs cycle.
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Emphasis and adaptation mine.
But, what happens if you don't have enough oxygen? Muscles consumes around 7 to 40 times more glucogen and oxygen during activity [[spanish Wikipedia](https://es.wikipedia.org/wiki/Ciclo_de_Cori)]. **Obviously, the lactic acid fermentation** which produces a lesser amount of energy without oxygen (Also regenerate NAD+ making easier the glycolysis). That **is the first part of the Cori cycle**.
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Remember that as I said before, this is an inefficient cycle, but at least it helps the muscles:
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> Overall, the glycolysis part of the cycle produces 2 ATP molecules at a cost of 6 ATP molecules consumed in the gluconeogenesis part. Each iteration of the cycle must be maintained by a net consumption of 4 ATP molecules. As a result, the cycle cannot be sustained indefinitely. The intensive consumption of ATP molecules indicates that the Cori cycle shifts the metabolic burden from the muscles to the liver.
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* **Glucose** + 2ADP → **2 lactic acid** + 2H+ + **2ATP** + 2H20 (muscle)
* **2 lactic acid** + **6 ATP** + 4 H20 --> **glucose** + 6ADP (liver)
* Net energy loss: **4 ATP**
Luckily, if you finish your activity, this cycle becomes more efficient:
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> The cycle is also important in producing ATP, an energy source, during muscle activity. The Cori cycle functions more efficiently when muscle activity has ceased. This allows the oxygen debt to be repaid such that the Krebs cycle and electron transport chain can produce energy at peak efficiency
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The Spanish wikipedia said that you can get painfully tired of doing exercise because our liver isn't enough fast to do all these reactions, so some of the lactic acids get involuntary stored in muscular cells producing [acidosis](https://en.wikipedia.org/wiki/Acidosis). Maybe having a bigger liver (or several small in strategic locations) can help our mucles. Or maybe increasing the activity of the [adrenal gland](https://en.wikipedia.org/wiki/Adrenal_gland) to produce more [adrenaline](https://en.wikipedia.org/wiki/Adrenaline) hormone which activates the Cori cycle in the liver (Futhemorer to [glucagon](https://en.wikipedia.org/wiki/Glucagon)).
### Additional information
Futhemorer the Cory Cycle there is very other similar cycle called [Cahill](https://en.wikipedia.org/wiki/Cahill_cycle), it isn't used when the body is doing activity, it's used when you are starving, so muscles start feeding with amino-acids to keep working and the liver regen them. I can post information about it if you think you could use also that.
**P.S:** If you have any question ask in comments. I don't bite and I love this!
[Answer]
Unsure of the other features, but for efficient lung structure I usually look to birds: <http://people.eku.edu/ritchisong/birdrespiration.html>.
Also, horses have an interesting mechanism by which they store oxygenated red blood cells in their spleen (up to a third of their total apparently), which are circulated when exercising. Like a natural form of blood doping.
A combination of the two would allow for efficient continuous oxygenation and bursts of fantastically high oxygenation. Having excess stores of blood may also help with continuing strenuous activities after sustaining wounds, and could also allow for extended activity in airless or toxic environments compared to humans. Hit by mustard gas and our supersoldier could simply cease breathing for a few minutes and survive off oxygenated blood stores.
[Answer]
About improving the efficiency of the oxygen transport system.
Respirocytes are an artificial analogue of red blood cells. Tiny sapphire capsules that can absorb oxygen in the lungs and release it in the capillaries. From the capillaries to the lungs, they , in turn, deliver carbon dioxide. Only respirocytes are hundreds of times more effective than ordinary red blood cells - each of them is able to carry much more oxygen molecules. (an injection of fifty cubic centimeters of the solution is enough to replace the entire volume of human blood ( 5 liters) in terms of transport efficiency, And if one liter of blood is replaced with a solution of respirocytes, the subject can not breathe for up to four hours)
Respirocytes are microscopic (several tens of times smaller than ordinary red blood cells ) crystal formations, hollow from the inside. The process of crystallization is similar to calcification of bones
[Answer]
**Regular, Human Lungs**
Homo Sapiens are *already* the world champion long distance runners. We have an extremely efficient respiratory system and only a few other species come *close* to matching it.
Humans at high altitude tend to develop lager lung capacity, so your super soldiers could have lungs larger than normal. My lungs, for example, have 150% the expected volume for a man with my age and height.
[Answer]
Well the most obvious solution is the use of gills. Gills essentially work by maximizing surface area of the bloodstream to the water, making replenishment of oxygen into the fish immediate and not requiring breathing or any such mechanism. The downside of this being that a creature with gills would need to constantly be in movement. Staying still would feel like holding your breath.
Gills would also have the disadvantage of being a weakpoint. It could be somewhat protected, but air must still enter and exit freely and easily, so aside from a mesh of bone, there can be little protection. Having a bucket of water thrown at such a creature would almost certainly cause water to coat the inner linings and prevent that creature from breathing properly. Assuming such a creature is superhuman, oxygen intake is going to be that much more important.
However, perhaps both these issues can be superseded. Requiring that the human is always in movement can be somewhat reduced somewhat by allowing the possibility of having a gill/lung hybrid. Air could still easily enter and exit, but with a small inner pouch that allows air to remain and therefore allowing the creature to move very little if not at all.
For what concerns the weakness to being doused with water, this can be remedied by using many small gill/lung hybrid glands all over the body near to major arteries such as near the hips, on the chest, below both armpits, etc. Dousing one such gland with water would not totally inhibit the creature, assuming the blood system is shared throughout the body. You'd have to completely submerge the creature in water to prevent it from getting oxygen, but the same could be said for us as well.
In addition to this, such a creature could get oxygen distributed far more easily to the body, and again, for an active creature as this, the more oxygen intake the better.
To prevent infection from dust, there would likely be eyelash-like hairs covering the entrance/exit of these glands. The glands would also naturally be angled such that standing naturally causes water to drain from it to prevent pneumonia type diseases from forming when exposed to water. Water would still likely often enter these glands, but this would not be a serious problem considering the sheer number of these glands on the person. However being half-way in water would mean breathing half as efficiently, so if you're looking to add a weakness, requiring these creatures to wade through water might put them at a disadvantage.
[Answer]
**Use a higher degree of anaerobic respiration.**
It is a mechanism that is already existent in humans and our muscles use this all the time when we have sudden jumps in the amount work we do, or when we have insufficient oxygen. It is the fastest form of getting energy, long before your aerobic metabolism can adjust to any load.
[See chapter 3 of this paper:](https://www.eolss.net/Sample-Chapters/C03/E6-54-08-01.pdf)
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Your super-soldier should have a stronger hart and liver to allow for faster transportation and processing of the resulting lactate. He will also have bigger blood-vessels. This way he will be able to sustain the anaerobic reaction much longer without even needing to start breathing more.
[Answer]
So there are some great answers on this post already but I feel like there’s a few simple things that may have been overlooked.
First off, humans can do endurance better than just about any creature on the planet already, so instead of major changes go for optimization! Other posts have already mentioned more hemoglobin to carry larger amounts of oxygen in the blood. Keep going with stuff like this. Larger lungs with more surface area means more air capacity and faster diffusion of oxygen into the blood and carbon dioxide out of the blood. A larger and more powerful heart will have a greater stroke volume, allowing for oxygen to be delivered to muscles and for waste products, like the very problematic lactic acid, to be taken away. More efficient oxygen extraction would also help. The average human only extracts a small percentage of oxygen from the blood, meaning that when you exhale there is still significant oxygen in your exhaled breath. Make your super humans extract a much higher percentage of the oxygen from the blood and that will easily double or triple their endurance.
As a secondary improvement, add enzymes to your super human’s muscles that break down metabolic waste at a much higher rate. This doesn’t directly help the respiratory system, but it will greatly improve endurance because once too much metabolic waste builds up too high you’re muscles **will** stop no matter how hard you push yourself.
So to summarize, bigger lungs with more surface area, stronger heart, more hemoglobin (not too much though, the blood will be too thick to pump!), more efficient oxygen extraction, and enzymes that catalyze metabolic wastes and cause them to break down much faster!
[Answer]
Two years late to the party, but nevertheless you can look up something called Respirocytes. (Basically high pressure capsules that store oxygen, a *lot* of oxygen) There's a lot of bells and whistles attached to it in the articles online, but you can make the respirocytes in our soldier's body dumb, in the sense that they only act as oxygen stores and nothing else. This removes a lot of complexity from its design. It's chemical structure is a hollow diamondoid, but if your super-soldier is producing things like graphene and diamond nanorods biologically, there's no reason it can't make these natively as well. Only problem is that they aren't passive carriers of oxygen (they use glucose to take up oxygen), so if you make them your primary blood constituent, be prepared to feed your soldier a lot more food. No passive uptake also makes them somewhat slow I imagine, so in high activity situations, they might end up being a poor substitute for hemoglobin.
They could replace or reinforce myoglobin however, in its function as cytoplasmic oxygen stores. Myoglobin acts passively, but oxygen stores in myoglobin are replenished when the creature is at rest anyway, so it's not that big a stretch to assume that the respirocytes could store oxygen using glucose when the soldier is resting and eating. Combine this with superior hemoglobin and and an avian respiratory system, and you've got the recipe for a soldier that can hold their breath for *hours*, or run for *miles* without the need for breathing. This also has ancillary benefits, like reducing the need to have a high cardiac rate in times of stress (like how the heart rate of top athletes are lower than that of untrained humans at the same level of exertion, but dialed to 11), causing less wear and tear on the cardiovascular system overall.
And you can also make respirocytes perform other functions, like absorbing free gases in the bloodstream when moving from high pressure to low pressure. (So no more diver's bends)
Any thoughts on this, anyone?
[Answer]
# Evolution has a long way to go
@Ender\_look gave a good review of some basic enhancements, but evolution has a long way to go. So let's keep fiddling with it...
**Proper respiratory system**
The birds are a fair start, but they still ultimately inhale and exhale through the same pipe, starting at the pharynx for ingesting food because fish originally gulped down air. The system should be enhanced so that inhalation is *constant* and exhalation has its own orifice. We'll convert the posterior air sac into a two-chambered pump with atrium, ventricle, and a "post-atrium" (like the expansion of the aorta for blood) so that there is a constant stream of air pressure passing through the lungs. The anterior sac will be linked directly to the outside by an orifice that is always passing air outward, making it relatively feasible to harden it against infections. For now we can leave the pharynx connection to screen incoming air and provide a reflex pathway to expel mucus from the entryways, despite the risk of choking (I see little reason to think that tracheotomies are a great thing).
**Our spleen actually works - most of us just don't know how to use it**
According to [recent reports](https://news.berkeley.edu/2018/04/19/enlarged-spleen-key-to-diving-endurance-of-sea-nomads/), traditional pearl divers make use of their spleens as effective as any marine mammal. Sometimes the slow pace of evolution is a good thing. :)
**Oxidizing agents**
There are many ways to ferment sugars for energy, all very low in yield. Your superior soldier needs his own oxidizer tank, like a rocket. Two options:
1. After you've eliminated the previous use of the thyroid gland, which is one of the most ridiculous kludges in all of biology and should be replaced by an insect juvenile hormone system that needs no iodine, you now use that gland to store large amounts of I2 in oxidized form. I2 would be a solid but we can mix it with a small amount of something gooey to keep it a little more workable. You'll need some very resistant follicle membrane structure; usually the body only handles I- as an ion or in thyroid hormone. When oxygen is low, the iodine will be used to regenerate it. (There is some energetic cost in doing that because oxygen is a better oxidizer, but you can have energy reserves and oxidizer on hand around your new thyroid)
2. Let's try to engineer an enzyme that can *stably* store O8 and *safely* break it down when needed. O8 is like O2, but 8 oxygens in a ring like sulfur. Terribly unlikely compound in ordinary chemistry. But if we do this we can store four times as much oxygen per 'myoglobin', and we're, ummm, going to try to evolve a small protein.
**Muscle latch state**
Smooth muscle can "latch" itself so that it stays contracted without energy output, by dephosphorylating myosin. Skeletal muscle in your soldiers should have similar potential, under voluntary regulation, so that they can carry heavy loads on specific muscles effortlessly.
**Full electric metabolism**
Advanced models should be able to convert water to circulating H2 and O2 using pure electricity at a recharging site, and then metabolize them back together in muscles for extra energy.
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[Question]
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Note- This question was partially inspired by the civilization in Star Trek: Voyager Season 6: Episode 12 "Blink of an Eye", plot [here](http://memory-alpha.wikia.com/wiki/Blink_of_an_Eye_(episode) "here").
You are an ordinary person, with an ordinary life, and an ordinary house. One day, you wake up and find something you weren't quite expecting. Out in your garden there appears to be a small stone age civilization. You don't seem to remember seeing them before, so you assume it just developed. This was, of course, of great interest to the world, once that idiot kid who won't leave you alone catches a glimpse.
Once the government arrives, though, something's different... they're no longer stone age. It appears they've developed a feudal system. In 2 or so hours. Remarkable! Either way, the government is here, and, in another 2 hours, so is everyone else. Oh look, there's the UN Secretary! And that's the UN High Command. You stand in a corner as Putin stalks by, and then you meet Rex Tillerson warmly (he does smell faintly of Vodka and petroleum, though). By this time, the society appears to have erected a small steam factory, and it is spoiling your Rhododendrons.
Now, with any belligerent military man comes the demand- "They could be dangerous! Kill them all!". For some reason, this receives astounding agreement, and they attempt to tear down the factory 'in the name of security'. This fails miserably as the commanders were talking fairly loudly, and the citizens caught wind.
Using their newly developed muskets, they fend off the men with a couple warning shots. The generals try again with force, but the people have learned their tactics, refined their technology. This continues, and no matter how hard the generals try, they simply cannot destroy the civilization.
Is this feasible? Can a civilization develop so rapidly? Can they adjust to, and anticipate, whatever may come their way? Can a civilization grow more rapidly than they are destroyed?
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There have been studies which show that creatures perceive time as a function of their own heart beat or metabolism. [Scientific American](https://www.scientificamerican.com/article/small-animals-live-in-a-slow-motion-world/) has a report on one of these studies. One of the key points in the article is:
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> These findings show that differences in how a mouse and an elephant sense time are not arbitrary but rather are finely tuned by interactions with their surroundings. A link between time perception, body structure and physiology suggests that different nervous systems have developed to balance pressures from the natural environment with energy conservation. Rapid perception might be essential for a hawk but would waste a whale's precious energy.
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Ever wonder why it is so hard to swat a house fly? That fly's pulse is 500 to 600 beats per minute (bpm), compared to your 60 to 100 bpm. To the fly, your hand or swatter is coming toward it at pedestrian pace. Plenty of time to buzz out of the way.
Galapagos tortoises never seem in much of a hurry and live nearly 200 years. It helps to have a 6 bpm resting heart rate.
Others have expanded on this idea and noted that a city has a "pulse" of one day (observable in traffic patterns for example), the earth of one year (daylight and climate), the sun 11 years, and so on. Scaling up and down in size tends to correlate to scaling slower and faster in the sense of time.
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Now moving on to your garden society, going to stone age to feudalism to democracy as you watch. How fast would their hearts need to beat? This depends on some variables you don't provide, but let's assume a linear relation between pulse and time perception, and that each minute for us is a century for them. I calculate that as a pulse 52.5 *million* times greater than ours.
Further, we have [this article](http://www.brainstuffshow.com/blogs/how-fast-does-blood-flow-throughout-the-human-body.htm) that tells us that the blood takes about 1 minute to make a round trip in a human body. If I estimate a round trip from my heart to my left little toe and back as 1.5 meters, I get a speed of 0.025 m/s.
If I reduce the round trip distance in the garden people to .15 meters and reduce the time to travel by a factor of 52.5 million, I get that their blood moves at 131,250 m/s. While not quite a relativistic speed, I suspect the blood pressure to sustain that would explode their little arteries. Not to mention the frictional heating caused by that amount of flow. These guys would be cooking themselves from the inside out.
This is just discussing pulse. If we get to the respiration rate that corresponds, we would get even more complications.
In conclusion: Not plausible, not without the "temporal distortion" of Star Trek.
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**A [General Intelligence](https://en.wikipedia.org/wiki/Artificial_general_intelligence) Appears**
It winks into existence (Quantum variation spawns one/ Extraterrestrial intelligence places it there for fun/ You bought the wrong magic seeds) and it has limited capacity to construct things out of organic matter. Its mission is simple: become the dominant entity on the planet. Listening to the local electromagnetic waves it learns that the dominant species on earth is humanity. Being only a general intelligence and not a super intelligence it decides to simply emulate humanity rather than try to come up with something better. After all, they had been pretty successful despite taking thousands of years to get there. It decides to build itself a few humans to start the process, small to be more efficient on resources (there is organic matter everywhere!). This decision takes .0001 seconds.
As a general intelligence with a wifi connection, your knowledge of the sciences is enormous but your capacity to carry it out is not. With your constructed miniature humans you begin to build, gathering resources that you need to expand. First starting with stone to build rudimentary structures to house your miniature humans (darn things need to rest and be protected from the weather). With your computer mind and access to the wealth of humanity's knowledge advancement comes as quickly as you can gather the resources. Fire was a no-brainer "discovered" in seconds, but things got off the ground when a rusty nail was found and you could make metal tools. The discovery of an ax head relly set things in motion because you could not build a working steam engine without all the steel it contained! You make it to the industrial revolution in a matter of hours, a feat that took regular humans thousands of years.
The process continues....
[Answer]
Read [“*Dragon’s Egg*”](https://en.wikipedia.org/wiki/Dragon's_Egg) by the great “hard” s-f writer (and scientist) Robert L. Forward. I think *Blink of an Eye* must have been influenced by it, as well. But this is **hard** s-f. (I just watched it again, and the episode is *obviously* based on Forward’s novel. The novel is much better, and where Michael Taylor waved his hands or made up technobabble, Forward was writing “hard” science fiction.)
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> Most of the novel, from May to June 2050, chronicles the cheela civilization beginning with its discovery of agriculture to advanced technology and its first face-to-face contact with humans.
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The appearance of the human craft in their sky stimulates their devolopment out of pre-history, and they finally build spaceships and launch a mission to visit the human craft in orbit, in a matter of weeks.
In 24 hours, they go from being able to crudely communicate with the humans using mideval tech on their end, to mounting the space exploraration. At one point a human at the communication console remarks how draining it is to have 15-minute life-long friendships, as the cheela counterparts go through their careers in successive generations.
The million to 1 speed differential is caused by two factors: a mere factor of 2 due to their world having very high gravity (67 billion *g*), and the main difference due to neuclonic reactions (using the strong force) being faster than chemical reactions. They are made of degenerate matter, without electrons taking up [*huge*](https://en.wikipedia.org/wiki/Atomic_nucleus) orbitals around the nucleus.
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Feasible in your back garden, sharing our envonment: no. Feasible where time runs a million times faster: sure thing.
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Another, more recent, story where this happens is [*Crystal Nights*](http://ttapress.com/553/crystal-nights-by-greg-egan/) by Greg Egan, this time in a simulated world in a supercomputer. Besides time running faster, they were set up to be able to evolve rapidly as an ultimate genetic algorithm implementation. The problem they were set was to produce general intelligence with a skill to create technology, and the human experimentors intervened with this goal in mind.
And your plot also reminds me of [*Microcosmic God*](https://en.wikipedia.org/wiki/Microcosmic_God) by Theadore Stergeon. In 1941 it was handwaved rather than being hard science, but it has the human inventor *guiding* the life to develop intelligence and then technology.
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Smaller creatures can be 'faster'. Neurons have to travel a shorter distance. Hearts tend to beat faster. So they could totally life faster and probably develop faster. However I don't think it would come anywhere near mere hours. That is totally unrealistic. However it can still be a compelling story I'd read.
Also I doubt their muskets no matter the numbers could stop any military in the last century. Even without using armor like tanks a rifle round is like an artillery shell.
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In the comments, I asked about the physics, and it was pointed out that the physics isn't such a big issue. The next point to note is that every civilization has this pattern. Every civilization alive has somehow grown its way out of every problem it has faced. Every civilization that died had somehow grown its way out of every problem except one. So the story is quite universal.
This universality makes the story really more one of "could such a small species fend off a large intelligent adversary?" The usual advantage of being large is that we have more resources, so we should be able to, say, raze the entire garden to plasma for a few minutes, which would eradicate any pesky creatures who depend on a structure greater than a randomly careening nucleus. However, with the physics handwaving involved, its not immediately clear whether the larger beings actually have such a physical advantage. So it's really a question of a race that has control over small timeframes vs. a race that has control over big time frames.
The interesting logical conclusion is that the race that has control over small frames wins *iff* it also has control over the long time frames, making it a superior race all around. Nature has found that "growth" is a very powerful tool for accomplishing such wins, so its a good match. If the smaller race has a more solid long term survival plan than the big race was, it will simply wait the big race out. The big race can't play the same game in reverse. It can't assume that because a nuclear explosion is "a blink of an eye" for us, that the small race can't respond *while* the explosion is happening.
The real question would come about in terms of interaction. How do they interact? To develop thousands of years of culture in a few minutes clearly calls for the species to move and think and speak that fast. To them, the loud "They could be dangerous! Kill them all" would have taken as long to come out of the general's mouth as, say, the time it's taken us to collect scientific observations on global warming (which, ironically, provides the same exact message). I would not expect any real meaningful interaction between them until the small culture got really advanced.
An interesting twist would be to have a trigger which causes the small fast race to slow down for a moment so they could interact with us (interact via talking or firing weapons, either way). In such a case, I would expect the first civilization to master the trigger to that mindbogglingly powerful ability to win.
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[Question]
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Would a seer have to learn how to operate a machine (say, a smartphone as a trivial example) if she can just observe herself operating it in the future? Would this make tutorials, courses, user manuals, etc. obsolete? Would technologies intended for precognitive people then be designed to facilitate learning by observation/imitation?
(And coming to think of it: Are modern smartphone apps designed for precognitive people?)
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You are proposing that a seer gaze into the future, and using her mystic talents, view the actions necessary to accomplish a particular task with a complex tool?
We have that. It's called "video tutorials on Youtube." So far, they have not made learning obsolete.
[Answer]
## Avoid Temporal Loops & Paradoxes by Cognizing Someone Else
In order to avoid paradoxes and all manner of temporal problems, she can just cognize someone else using the gadget. A particularly good choice might be someone teaching a class on the gadget.
## Still...
Even if temporal loops and chicken/egg paradoxes aren't a factor, I think there are still many other important factors. For example:
* The precog might see herself turning a knob on a gadget, but does that cognition merely give her visual information only, or does it also contain her future thoughts as she is turning the knob? Simple visual information may not be sufficient to teach her all she needs to know for all possible uses of the gadget--her cognition might need to also contain her conscious mind's thoughts, as well as any subconscious/reflexive/body-memory information (such as how to ride a bicycle)
* There are different styles of learning and some people do better with some styles than with others. For example, visual learning (learning by watching), auditory learning, manual learning (learning by doing). So, if the precognition does not contain the type of data she uses to learn best, she might not learn as well. For example, if she needs to hear things described in order to learn best, but her precogs only contain visual data, she might need more help.
* Cognition can include data from the conscious mind and the subconscious mind. Both of these levels of consciousness can be cognizing incoming data from the five physical senses as well as mental processing of this information and the resulting responses. So, a certain person's gift of precognition might be limited in some ways, such as sight only (essentially precognitive clairvoyance) or precognitive clairaudience, or combinations of any of these things. Someone with master-level precognition would theoretically have conscious access to all types of information desired, while newer precogs might only have some partially developed skill.
* Another frequent theme/issue with precognition is how voluntary it is--often the precog does not have conscious control of perception, and so it's more of a gift, whereas someone who is more masterful can control the ability more or less, potentially all the way up to omniscience.
* Another theme often is some degree of discomfort or disorientation associated with the precog events. These kinds of negatives might make learning solely by precognition undesirable.
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Watching a task be performed,and actually successfully doing the task yourself are two very different things.Even going into a situation with an understanding of the mechanics involved can still be difficult.I don't believe learning could ever be rendered obsolete for a precog. Even after learning something and doing it many times,it may still be necessary to revisit some aspects of it through use of a manual or other learning material.
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How is the precog observing herself using a device different from a normal person observing someone else using the device? I can observe someone coding perl, but it wouldn't make me an expert programmer; I'd have to learn from the basics. I'd expect it to be the same for the precog.
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No, I doubt very much precognition will ever make structured learning obsolete.
In your example, there are a couple problems - one is that your precognitive will not *understand* the process just because she sees herself doing it in the future (even perfectly). So, she can twist the knobs and push the buttons, but will have no way of knowing why that produces the result it did, or how to change the process when she got or wanted to get different results. One example is, watching and copying a click-by-click walk-through of, say, how to call person X (on this phone) will let the seer...call person X. On that phone. Not let them call person Y, or Z. Not send a text message to person X. Not receive a call from person X (or Y or Z). Or receive a text message from them. They can't check their voicemail, or return calls, or input contacts. They can't even repeat the *same* action, a call to person X, with a different brand of phone (buttons in wrong places, or different operating system, etc)
She can *eventually* learn all these things, by blindly memorizing the sequence of each action and slowly piecing together patterns with logic and extrapolation - which is a slow and inefficient way of learning anything, as compared to learning the reasons underlying the actions that need to be taken, and how and why the parts work together to get the result. Its a lot easier to learn to read a map than to memorize and extrapolate from looking out the window from the passenger seat - and it is *too* easy to not even try, and let the gps navigate for you, until even a drive you've made weekly for years is impossible without the gps telling you what to do.
The other problem is that precognition is...nonstandard. For example, how easy is it to turn on and off, how difficult is it to show exactly what the precognitive is looking for, how much information can be taken in via precognition, how easy is it to remember it...
So your precognitive would have to be a *perfect precognitive*, they would have to be able to specifically and reliably call forth the exact sequence of events needed to make the "whatever" work, *whenever* they needed it to work, they must always call up successes - or else they would perfectly reproduce future failures, they would have to learn it somehow for it to be in their future. They must be getting the information at the right rate to successfully copy it, and the right information to boot - that is, if they call up a vision of a future when they are comfortable enough to speed through the process, or when they use shortcuts that they haven't set up yet (example: pre-programmed contacts), or even use a different method (example: a future device or different app or even an update they don't have yet) they may not be able to successfully follow along and make it work with what they have in front of them.
So to make structured learning obsolete - not just not unnecessary for a specific character, but *obsolete*... you need perfect control over your precognition, you need **everyone ever** to be precognitive, *and* with perfect control over that precognition, *and* able to learn the information (perfectly) via the methods the precognition can provide (visual images if "visions", extrapolating from specific to general, using logic to work out the gaps between what's shown and what's needed)
So, yeah, I wouldn't call being able to mimic a string of actions from the future "operating" the machine, I would consider it the person getting walked through the (specific) use - even if the person walking them through it is themselves from the future.
And you have a bigger problem... seeing and mimicking a specific series of actions may be enough to, say, use a smartphone - it is nowhere near enough to *make* one. Not enough to design, or manufacture, or assemble one. Or program it, or design apps for it, or troubleshoot when things go wrong, or fix it when someone messed up at any previous step, or any number of other things. For those kinds of things, you need to understand what it is, how it works, and what it does. Even a vision of the (future) blueprint is useless unless you know what all the markings are, to be able to faithfully reproduce them ("Oh, you needed a value here? I thought it was a smudge!" or else "and what does that abbreviation stand for?") Or maybe person X has a correction or alternative to person Y's vision-ed blueprint, but the vision didn't show *corrections*, so should it be altered or not? You need to know how to read the blueprint, and which materials to use and how to get them, and how to put it into production, who to talk to, and a host of other things.
In short, you need knowledge. You need to learn things, and teach them. You need people who can work together. You need people to have ideas, develop them, do the underlying research (scientific study results via precognition? ah, NO). And really, the best way to get these things is by some kind of structured learning. Classes, groupwork, projects, innovation, methods of doing things - it might, perhaps, be different from they way education is structured now, just like memorizing is much less important in education now than it was historically because of the easy access to facts via the internet - but it will be structured somehow, because that is the easiest way to make this education standardized, to make sure all the basics are covered, and that people will have the skills they need.
Bonus question - without that there is a genuine question of who runs the world? I mean, if people are just repeating what their visions they will do, if they don't need to learn anything... who regulates that world? Who determines allocation of resources? Who decides *what* the visions teach them - some people are better at some tasks, or have different abilities, so who decides who goes to which jobs (and which jobs are prioritized), who regulates the industries or the markets, or checks for environmental and safety hazards, or makes long-term decisions... who fails, for heaven's sake, when they have to know they will - but what world is this of no one tries?
Are you picturing a **silent** world, where everyone is running on some hive-mind - or actually a pre-planned future-vision-dictated-world, but there's no practical difference, is there - everyone just *knows* where they need to be, what they need to do, because precognition told them so? where people just walk into jobs they never trained for (or even applied for, because *the visions* say who will succeed therefore who bothers to apply) and start working, repeating sequences of actions that they don't understand towards ends they don't recognize? Do people act out whole sequences of unalterable, meaningless events, or do they just skip it because everyone already knows, because everyone can just precognition the events and conversations and the results? Meetings where everyone has already precognition-ed the information, mouthing apologies when everyone already precognition-ed the explanation?
Yeah, the only way precognition replaces (structured) learning is by replacing cognition. You don't need to learn, if you don't need to think - just obey the visions. Obey. *Obey*
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[Question]
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By the time we develop the technologies necessary for travelling between stars, I think it is fairly likely that we would have already developed the technology to digitally augment, edit, and upload our minds. After that point, it's almost certain that transhumans are created, and posthumans shortly after that.
Is it more likely that the denizens of the Sol system that end up going out and exploring the galaxy will be humans or digitized posthumans?
Is there anything to prevent posthumanism from developing before we develop interstellar travel? Is it plausible to expect that human governments would impose legislation to prevent posthumanism, and the inevitable singularity afterward? If so, would such legislation even be effective?
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Channeling the words of Charlie Stross humans basically aren't built for space.
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> We're human beings. We evolved to flourish in a very specific environment that covers perhaps 10% of our home planet's surface area. (Earth is 70% ocean, and while we can survive, with assistance, in extremely inhospitable terrain, be it arctic or desert or mountain, we aren't well-adapted to thriving there.) Space itself is a very poor environment for humans to live in. A simple pressure failure can kill a spaceship crew in minutes. And that's not the only threat. Cosmic radiation poses a serious risk to long duration interplanetary missions, and unlike solar radiation and radiation from coronal mass ejections the energies of the particles responsible make shielding astronauts extremely difficult. And finally, there's the travel time. Two and a half years to the Jupiter system; six months to Mars.
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Admittedly Charlie was talking about interplanetary travel, and this applies in spades for interstellar travel. Stross says there are solutions to these problems, but as he suggests in his SF novel *Saturn's Children* (2008) robots and technological creatures are better suited for space travel. Information about the novel can be found [here](https://en.wikipedia.org/wiki/Saturn%27s_Children_(novel)). A bit scant on his posthuman argument. But Stross himself gives more on the circumstances and background to *Saturn's Children* [here](http://www.antipope.org/charlie/blog-static/2013/07/crib-sheet-saturns-children.html). It's also an entertaining read.
One of the early versions of posthumans was proposed as a solution to the rigours of space travel by [Manfred E Clynes](https://en.wikipedia.org/wiki/Manfred_Clynes) and [Nathan Kline](https://en.wikipedia.org/wiki/Nathan_S._Kline). This concept was the [cyborg](http://www.theatlantic.com/technology/archive/2010/09/the-man-who-first-said-cyborg-50-years-later/63821/).
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> "Space travel challenges mankind not only technologically but spiritually, in that it invites man to take an active part in his own biological evolution," the Astronautics paper began. "Scientific advances of the future may thus be utilized to permit man's existence in environments which differ radically from those provided by nature as we know it."
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Clynes and Kline "coined the word "cyborg" to describe an emerging hybrid of man's machines and man himself. The word itself combined cybernetics, the then-emerging discipline of feedback and control, and organism." A fusion of human and machine as a creature fit for space travel.
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> environment for him in space . . . Artifact-organism systems which would
> extend man’s unconscious, self-regulatory controls are one possibility
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Their September 1960 paper, *Cyborgs and space*, in *Astronautics* can be found [here](http://web.mit.edu/digitalapollo/Documents/Chapter1/cyborgs.pdf).
Interstellar travel will be one of the biggest challenges for space travelling human beings. When all the problems taken together it becomes obvious that mere fragile biological humans could not survive interstellar space. Converting humans into cyborgs, uploaded minds in cybernetic systems or digitized constructs may be the only solution.
Effectively interstellar travel isn't feasible until humans become posthumans. It doesn't matter if the technology for interstellar travel precedes posthumanization, travel to the stars will take place once posthumans take the helm of our starships.
Posthumans and interstellar travel are made for each other.
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In the short to medium term, we have far more understanding of the sorts of technologies conceptually needed to travel in interplanetary space and even nearby interstellar space than we do in even understanding how our minds work, so the idea of post humans spreading out among the planets and stars is a bit moot. Elon Musk will almost certainly be on Mars before anyone even has an inkling of how to do mind uploading.
So the real issue is how fast transhumanism will be developed.
Moving into exotic, strange and hostile environments like the moons and asteroids of the solar system will certainly give a boost to research which will lead in the directions of transhumanism and post humanism. Creating modifications (genetic or technological) to make humans more radiation resistant, more efficient in metabolizing food, capable of existing in more exotic atmospheres and so on makes humans more capable of living and working off planet.
Even if some governments on Earth are against modification, not everyone will be opposed (some governments might actually desire better people to work on their space projects). As well, the people in space, free from their governments on Earth, may choose to carry out programs of modification of their own to better survive the conditions in space.
So in the short to medium term, humans will be spreading through the solar system, but as time passes, a larger and larger percentage of people in space become transhumans. Martians might not be visually different from humans, but microscopic investigation will show modified bone structure, glandular changes to control bone density, red blood cell production and other modifications to adapt to Martian conditions.
With the uncertainty surrounding the idea of digitally uploaded humans, trying to predict the timeframe of when this will happen isn't really something that can be predicted accurately. One thing which might seem counterintuitive is digital post humans might not even want to travel in space. Since electronic signals are faster than electrochemical signals in the brain by a factor of 1,000,000, the 1.3 second light lag between the Earth and the Moon would seem like a subjective week for such a being. The time lag for more distant planets becomes increasingly more arduous for uploaded beings, and the months or years of realtime travel between planets would seem to take centuries for an upload. If it takes a thousand years to get to Alpha Centauri using a solar sail, an upload would be stuck for subjective eons.
Digital uploads might have other means of dealing wth this (including changing their perception of time or modifying their clock speed, or simply living in Matryoshka brain living in a simulated universe. Post human futures will be virtually unknowable to people like us.
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This is something I've often wondered about myself! And the biggest deciding factor, I'll have to say, is technology. Specifically, can humans achieve FTL travel, and/or terraform. So here are two possibilities I can consider.
1. **Star Trek-Style**
If FTL travel is discovered, and humans can reach nearby systems in relatively short times, then it's not likely humans will evolve too much. The basic human form will be able to manage their own environments to fit their needs; therefore, there's need to alter the design. If it ain't broke, don't fix it. Humans may be able to advance their brains' wiring (I.e., able to process thoughts better, etc.), but as far as physical alterations, it'd be fairly consistent.
2. **All-Tomorrow's Way**
Assuming FTL travel isn't possible (or, more likely, takes a *really long* time), then some evolution would occur when colonizing new worlds. Even considering terraforming technologies, gravity and sunlight exposure will definitely play big effects on human physiology.
For example, Human Martians wouldn't need to be as bulky or short to live on such a world. They'd probably end up looking taller and more spindly than their Earthling counterparts. Humans out near the further reaches of the solar system might end up copying the Neanderthals body plan - short, stocky, built to keep warm.
As for digital augmentation or digital humans...that's harder to say. It depends on the path of technological development. I think it's something to consider for *inter-galactic* travel, but as far as anything within the solar system, or maybe even within our section of the Milky Way, I'm skeptical.
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I think that the first people who make use of mind uploading will be the very rich and powerful. They will lobby to ensure that it is available to them to live on past their mortal meat existence, *and* get to keep their wealth, influence, and civil rights.
See [this question](https://worldbuilding.stackexchange.com/questions/51746/when-will-uploaded-minds-be-a-reality) for thoughts on the timeline driven by economics: it will be open only to the wealthy at first and will gradually become possible for middle class etc.
Eventually the uploaded will outnumber the “living”. But long before that, they will be the oligarchs, plutocrats, billionaires, and heads of state from the previous century and the dominant holder of wealth and power.
In order for the luddites to stop them, even at an early stage, would require a movement of the scope and size that topples nation states. Imagine someone who controls a personal fortune of billions and directs corporate assets on the scale of half a trillion; he’s used to making government inquiries against him simply go away, and controlling public opinion not just on products he’s selling but towards his personal positions.
*How could the population possibly come together to stop him?* In a free republic he controls the masses through advertising and spin, and in a different kind of regime he simply pays off the government (if the government isn’t already the puppet of him and others like him).
Now this is happening to *all* the aging or ailing über-riche, all over the planet, so the right kind of situation such as a religious backlash or a powerful leader making him or his money “go away” would be a one-off solution for a specific case or culture—you need to stop *all* of them. As for the one-off, he might get out of that too, defecting to another country that eagerly harbors him (and his money) for a fee; or disappear into the underworld.
So you don’t just have to topple the power base of **a** nation, but of **every** nation, with different cultures and styles of government, **and** prevent it from happening covertly.
In short, you have to prevent advanced technology from existing on a global basis. It has to be cut off at a point where it would require “obvious” infrastructure to build, like chip fabs.
Or, you need a pervasive surveillance state across *all* nations, to prevent anyone from doing that (and anything else you want to outlaw).
I think, barring the collapse of civilization before that, that it cannot be stopped.
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[Question]
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In my fictional country, you are not allowed to be a vegetarian. Meat eating is recommended and mandatory.
The law prohibiting vegetarianism was created somewhere around 1780-1850.
The question is:
**What could cause a country to frown upon or even outlaw vegetarianism and make meat eating mandatory?**
EDIT: Assume this is our earth. Northern Eurasia. A realistic country, not a group of survivors.
[Answer]
If vegetarianism were one of the tenets of a religion or ideology that has been overthrown by the present rulers then it might be outlawed as part of the package of laws against the forbidden belief system.
I don't know whether your world includes actually existing religions, but if it does, most schools of Buddhism, some schools of Hinduism and the Jain religion are all vegetarian, so you could assume one of these religions had gained substantial numbers of converts at some point in the past of your Northern Eurasian country. Later on there was a reaction against them and the religion was banned, but still continued to be practised in secret by some. Alternatively you could posit that a vegetarian sect of Christianity (e.g. the Seventh Day Adventists) was more influential in your world. Or of course either or both of the vegetarian subversives or their persecutors could be followers of a non-religious ethical system. Conflict might be particularly bitter if one group was and the other group was not a religion - either way round is possible, although the persistence of a taboo even in the face of persecution is particularly characteristic of religious taboos.
Vegetarianism could easily come to be seen as the defining characteristic of the enemy group, even if it were not actually their main doctrine, because willingness to eat meat is something that can be used as a test of loyalty. The police would demand that suspected believers eat some meat to prove their innocence.
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1. **Plant based alternatives are an issue.**
To have a sustainable vegetarian diet, you need access to plant based protein - legumes, avocado, etc... If that requirement is a problem, that's the root of prohibition on veganism (non-vegan vegetarianism is not affected as they can use milk or eggs). E.g.:
* An epidemics killed off all of protein-rich plants
* Said plants have "more important" uses - e.g. they are needed for military purposes. Going on a really long limb, legumes are used for producing foul-smelling human-produced gases for chemical weapons :)
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2. People mentioned **religion**, but hand-waved why that would be the case.
Specific religious roots could be:
* "**Heathen cultures around us were/are vegetarian**".
This is an argument justifying a TON of rules on how conduct one's life - including diet restrictions - in Judaism. E.g., the rule isn't "God said don't do XYZ because it's bad" - it's "Don't do XYZ because all he heathens around you do it".
* **Non-religious secular reasons being codified into religious law**.
Again, going with Judaism as example, many people have a scholarly opinion that some of the kosher laws are merely Judaism's version of FDA. They were memetically added to the religious practice because people practicing such rules were healthier and thus that meme had a higher chance of surviving and propagating.
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3. Same reason anything happens in Earth politics. **Interest groups/lobbying**.
Someone in Big Animal Agriculture (or whatever passed for it in your country at the relevant time) paid a hefty bribe/donation to law-making entity, to ensure a captive market.
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4. Similar to #2a, but in **geopolitical** instead of religious context.
The country was in a major war with Luftisia. Luftisians are avid vegetarians. The war was nasty, long, and anyone who in any way shape or form can be accused of Luftisian influence/sympathies is in for a rough time.
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5. A country had a massive influx of (probably illegally arrived) immigrants from a vegetarian country/culture (being Earth before 20th century, probably India?).
The powers that be **wish to discourage said culture from existing** - either by driving adherents away, or making them assimilate ASAP.
For a modern example, see prohibiting circumcision all around Europe.
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6. Cattle used for "fluoride brainwashing"
So... you wish to brainwash your populace via use of a chemical that we'll alludingly call a "fluoride".
Except... you don't have a way to "fluoridize" the central water supply in 1700s the way you do in 1800s. Nor can you poison every farmer's plants.
BUT... you CAN more readily disperse the chemical to the cattle! (I can offer specific ways but that'd be a separate question :)
So, to ensure people don't avoid the brainwashing, we are prohibiting vegetarianism. Probably, along with hunting wild animals.
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The first thing that comes to mind is a religious mandate to eat meat in a theocracy (or a government with a strong religious foundation, even if it isn't technically a theocracy). Why the religion would demand that people eat meat is up to you. Perhaps certain animals are thought sacred, and souls are strengthened by members of the flock eating them regularly.
Alternately, maybe there just isn't a lot of produce available in the area and it needs to be rationed. Since vegetarians have to eat a lot to get the calories they need to survive, vegetarianism is outlawed to stop them hogging all the vegetables. It doesn't have to be an outright ban either; if vegetables are rationed, it might simply be impossible to live as a vegetarian.
A public health argument is possible. If the health care system is government run and they believe vegetarians cost more money to care for than people who eat meat, it's completely believable they might outlaw vegetarianism or discourage it with taxes or fines.
Perhaps there was a very active eco-terrorist movement of radical vegetarians in the past that caused lots of problems, and vegetarianism was outlawed as part of the government response. Vegetarians are now looked on with extreme distrust and assumed to be the spiritual descendants of the eco-terrorists of the past.
It really just depends on the social context of your fictional country. Many of the laws we live under exist not because the things they prohibit are bad in and of themselves, but because society has decided they shouldn't be allowed for whatever reason. Given that, if you lay the right groundwork practically any justification for outlawing vegetarianism will do.
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**The easy way out** - If you want to stretch the imagination, you could prepare an argument that a fungal disease that affects only humans, yet benefits bovine, etc., has spread along the fauna.
**Historical precedent** - In one case (I looked for a source, but only got some shocks via google - do NOT google it), in an area of China, I recall they were ordered off vegetation, because the use of human feces as fertilization for plants had created a disease epidemic. They were restricted to meat.
**(faulty) Scientific argument** - It's been argued that homo-sapiens advanced because the proteins in meats allowed the brain to evolve further. I understand that our genes were developed when we were enthusiastic meat eaters. Perhaps a religious or scholarly leadership would shape the legality of what is allowed to be eaten as a (faulty) strive for greater mankind.
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As a Vegetarian, the first reason which springs to my mind is this:
Meat eaters often react aggressively to people who are vegetarian for moral reasons (yes I speak from experience and no of course that doesn't apply to everyone, I wrote "often"). This is because there is an implied "You are behaving amoral" in telling a meat eater that you don't eat meat for moral reasons. This behavior is currently becoming less frequent as vegetarianism is becoming more accepted. But imagine the time when the law was made: If there was some sect or other minority group which advocated vegetarianism, publicly, this would offend a great lot of people. From this starting point I can imagine various chains of events which could lead to a ban of vegetarianism, choose/imagine your own.
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I think that the most realistic way this would occur would be via economics. Say that in 1750, or some other time prior to truth in advertising laws, a pig farmer began creating scary ads about a neighboring corn farmer's products, like hiring a town crier to shout about how their ailing mother was struck with dissipation after eating too much corn gruel, then claiming that after one of her sows ate the corn and she ate the sow, she got better. The farmer might then say that his pigs filter out the heinous poisons in corn. Then, he goes to the corn farmer and says listen, nobody is going to buy your corn, but if you sell it to me for my pigs, I can guarantee you steady orders.
All the stuff about religion and mythology could then arise therefrom. For instance, the farmer might tell the local church that if they stop saying that pigs are unclean and start talking badly about corn, he'll give them one out of every five pigs he slaughters for free.
Eventually, the original farmer might be forgotten, but in order to compete, others would likely adopt his business practices until the ideas they promote about anti-vegetarianism became widespread in your society.
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You need a workforce that can do extremely hard labour.
A diet of meat (not steaks, rather stews, casseroles) and beer (low on alcohol compared to modern standards) could give you the calories needed to build canals or railways (The London - Birmingham railway has been said to involve more work than building of the Great Pyramid of Giza, taking about 20,000 men 5 years compared to 100,000-300,000 men about 20 years to do the pyramid (Those calculations are only mentioned to show the scale of hard work, not be considered accurate)).
So your country needs to build canals, bridges, roads, prams, ships and wagons fast. Very fast. To be able to defend itself from an enemy you know is coming.
You need every hand on deck, from before dawn till after dark, very short meal breaks. Drinks should give the workers energy as well, and some pain relief.
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Safety first, of course. The same reason no one goes beyond the wall, past the river, or into the forest: safety. If the local flora - all the local flora - is poisonous or otherwise harmful to humans, it would make sense to ban the consumption of local plants. Supposing humans have been in the area for their development, this would be known and the normal would be to not consume plant matter. The country's law would, in essence, be a formal wording of a social norm.
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Make it a practice of a religious group that is persecuted. Making anything associated with or especially *required by* that group ilegal is exactly the kind of thing that "concervative" groups would do.
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Vegetables can be processed into nutrient paste with 20x times the nutritive value of baseline vegetables.
As such, eating non-processed vegetables is like eating 20 shares of food.
Add some small natural disaster, and to feed everyone, you want to ban any vegan diet.
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**Panic over a disease**
Recently, there have been a lot of health scares regarding food-borne illnesses. For example, a large amount of Romaine Lettuce was found to be infected with E. Coli. In response to the threat, the news repeatedly warned the public not to eat contaminated lettuce.
You can use that force of panic. If multiple news outlets report that a large amount of vegetables are contaminated, it will send people into a food panic (it's like a food coma, but with panic). People will throw out all their veggies to be "better safe than sorry". Even more effective, if the vegetable producer alerts news outlets that its food is contaminated, outlets will take their word for it because no one wants to lose money over a fake health scare.
If you can create enough panic, you can start claiming that the disease is spreading via the crops themselves, even if they aren't eaten. Report fake casualties and start burning fields. Eventually, people will give up on plants and go back to meat. Every few years, report a story about some unfortunate soul who decided to eat a vegetable and ended up in a coma. Now, when you pass your anti-veggie bill, no one will care. Besides, all the veggies are infected anyway, right? I bet vegetables doesn't even taste good.
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> It took Alynn two days to escape the villagers, her would-be killers. Two days - the same amount of food she'd taken in her rush to escape.
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> Being magical was all very well, but its reliance on her eating was sometimes annoying. Getting food might not be a problem, but if she couldn't find enough she wouldn't have as much energy the next day - then even less after that.
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> Now, stuck in the Chiral Forest five days away from the nearest friendly town, Alynn felt doom impending: how could she keep going?
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Alynn's back! [Last week I asked about](https://worldbuilding.stackexchange.com/q/15036/2685) the scientific principles behind her magic. The answers there confirmed the viability of what I'd come up with. Alynn has magical energy, which she can use, converting with 100% efficiency, on any task she can think of.
The amount of energy is dictated by how much she eats: she gets half a Calorie's worth of magical energy (2000J) for every Calorie she eats. This means, on a normal day, she'd end up with about 4MJ of energy.
Now, she's stuck. Five days away from her target, where she'll try to start her life again, she's out of food and water, and has no shelter. And no experience with this sort of thing: while she can kill animals easily, they run away because they hear her coming; and she couldn't tell the difference between a sloe berry and a deadly nightshade berry.
How can she keep herself walking? This is the first day, so you have 4MJ to spend on getting her enough food, water, and shelter to get to the next day. After that, she'll have the energy you gave her in that consumption.
Her energy can be used for *pretty much anything* - apart from creating matter. She can synthesise things apparently out of thin air by finding the correct molecules (yes, her brain can do this) and reacting them to form the correct compounds, but only if she can make the correct conditions for the reaction. She cannot create new atoms or molecules.
Also note, if she creates an exothermic reaction, she won't absorb any energy from it (or any other energy source for that matter).
[Answer]
**She can eat wood.**
Presumably she won't know how to create her own [cellulase](https://en.wikipedia.org/wiki/Cellulase), but by finding some termites she can either observe how they do it (assuming she can also *observe* things on the molecular scale) or she can gather the cellulase from them. She can also [eat the termites](https://en.wikipedia.org/wiki/Termite#As_food).
Humans [wouldn't need significant modification](http://dujs.dartmouth.edu/fall-2010/turning-waste-into-food-cellulose-digestion) to digest cellulose (wood/plant matter). By using cellulase to help break down the cellulose, she will be able to extract more energy than she puts in, a net positive. Water would be liberated from the plant material during digestion.
Surviving for five days in the forest is actually not too hard for regular people. Her abilities will just allow her to come out much stronger than a regular person might. She can still forage berries, drink from streams (she can boil it to destroy the parasites, ~80 Cal/liter), and eat other (non-colorful) bugs that she finds.
Additionally, to further optimize her own energy usage she can make other slight modifications to her body while she's in escape mode. Like turning off hair and fingernail growth ([might save 10 Cal a day](http://boards.straightdope.com/sdmb/archive/index.php/t-461346.html)) and [slightly lowering body temperature](https://en.wikipedia.org/wiki/Dormancy) during the day.
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This is really, really easy unless Alynn doesn't know very much about how to use her magic or about the natural sciences. If you want to make it a challenge, you'll need to decide what she doesn't know (once you learn more yourself than she would know).
Firstly, as has already been pointed out, Alynn doesn't need food to survive, just water, and maybe not even that (depending on the weather). There are plenty of cases of [people lasting far longer](http://blogs.plos.org/obesitypanacea/2011/05/13/the-science-of-starvation-how-long-can-humans-survive-without-food-or-water/). As long as she didn't get lost (she might), and didn't waste too much time searching for food she couldn't find, she'd be okay.
But there are much better opportunities than that. She can use her energy to replenish her cellular ATP stores. Turns out that human metabolism is only [about 40% efficient](http://antranik.org/intro-to-cellular-respiration-the-production-of-atp/). If she gets 50% more from magic, she can cut her food consumption in half just by regenerating her own ATP, or power herself for more than one extra day from the stored energy alone.
But then, why is she walking? Walking isn't very efficient. Cyclists going 20 mph (over 5x walking pace) use only about 100W to overcome air resistance. If she can perform any sort of levitation (and how could she not, being able to move molecules so easily?), her 4 MJ would let her travel for some 40,000 seconds at 20 mph, giving her a range of some 220 miles. I suppose she can't use this, though, or she'd have lost her pursuers in a few minutes instead of two days.
So suppose she wants to hunt. Animals don't do very well without oxygen; all she needs to do is pull the oxygen away from an animal and wait for it to collapse. Or she could depressurize the sky around a flying bird, and go pick it up after it crashed to the ground.
But you don't even need to go after animals. Trees have sugar in them; pull it out and eat it. You can get water from trees, or from the soil. Even bacteria use sugars and fats to store energy; if you can manipulate molecules you can summon hunks of fat, sugar, and water right out of the bacteria in the soil. Or, since forests have high humidity, just pull water out of the air.
So this *isn't* an issue, really, of what's magically possible with this kind of magic. It's an issue of what Alynn's limited knowledge and experience allow her to do. And there, the best choices are ones that fit with other parts of her story.
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My initial thought was that: Well five days? Just keep going. Spend as little magic as possible.
Especially on food she would spend as little as is bearable. Given the amount of energy of (bodily) fat (40 kJ/g) she will lose only a few pounds along the trip.
Water is a little more tricky as it is not that simple to go without. Two approaches come to mind: 1) minimize loss of water (think *Dune's* Stillsuits) but making one of those with just 4 MJ seems a little tricky (maybe do the math later). 2) don't try to use your magical energy to directly "make" water, use magic only as leverage to find naturally existant water. I'd like to suggest to "make it rain" but I'd assume that the energy needed to do so would be prohibitive. But then again maybe the climatic conditions are not that bad to assume that potable water might be found with little effort.
Also summon a kind of shelter the first night that is easy to carry along (think rescue blanket) and be used repeatedly without resorting to magic. And while she's at it summon the "Ten Essentials" all along: at least a knife and matches would be great to have non-magical tools at hand. And according to the rules "summon" would mean to transform nearby and existing materials to something useful. (But it is really hard to put some numbers on those processes without making some awefully long-winded guesses.)
One final thought. As stated Alynn is not exactly the Ranger-kind-of-a-gal. So she is not knowing anything about how to survive in the wilderness and not knowing what berries to eat. It therefore seems prudent to get herself some help... and while conjuring a little helper seems out of the game given the restrictions in available energy it could be possible to influence existing creatures to be helpful towards her? Say "mindtrick" a wolf or an eagle into supplying her with some game? While she's at it she can also literally depend on the eagle's eyes to watch out for her chasers. In that case make it an owl for superior night vision.
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Five days is easy for anyone who knows two simple rules - stay warm, and drink water.
A person who does not follow these rules can die in less than 24 hours of hypothermia in surprisingly temperate environments due to simple evaporative cooling. Day one, first thing, she needs to reinforce her wardrobe with anything she can find, get, or make. At night, even if it's unsafe to sleep, she needs to stop moving and take whatever shelter she can find or build. This should be pretty easy for a mage, and so should starting a fire - this would have a relative caloric gain by reducing the amount of energy required to maintain the body's core temperature.
As far as water goes, Alynn has the unique advantage of being able to simply extract what is needed from nearby plant life - this would be far, far simpler than attempting to manufacture it. Large trees can transpire 100 gallons in a day, so its safe to say that, unless these trees are all dead, there is sufficient water nearby - especially so for someone who can manipulate atomic interactions.
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Everyone knows the three Requirements of survival. Shelter, food, and water. Being in a deciduous/coniferous forest it means that the trees drop whatever is no longer needed, leaves, branches, pine cones, this generally makes a covered floor which will house a large amount of edible bugs and grubs. As long as she can get by the 'ick' factor food is no trouble at all. Sh can find these under large piles of leaves or in dead logs the the forest drops. Now she may not understand this since she has never been in this type of situation before but she would know that she needs shelter and she needs water.
One way of addressing it since it has already been determined she can use magnetic fields IS the Raizen's Method <http://www.utexas.edu/opa/blogs/research/2010/04/26/atom-stopper/>
Using this method she could slow the atoms in a Tree trunk effectively freezing the water in the trunk itself. When the water freezes in the trunk it expands and often will explode felling the tree, Providing shelter. Increase the area of the magnetic field and it will generate frost on the leaves which can also be used to drink like ice chips. The generation of the magnetic fields would be a restrictive field instead of a propulsion field and would require the same amount of energy to stop a copper bullet. The difference here is that it needs to be constant for a period of time instead of instant. This prevents other atoms from exciting the encased atoms in which they will eventually slow.
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[Question]
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So, in this fantasy preindustrial world almost everyone can cast small spells like spark within a one meter radius from their mouth.
Taking that into account, igniting mechanisms like matchlocks or flintlocks might seem redundant.
What would firearms look like and function in this world? And what would be the simplest firearm mechanism possible?
[Answer]
**Huge impact**
Given that the OP specifies that the "Spark spell" can ignite powder through a metal barrier, firearms are suddenly much more effective at each stage of development. The increased effectiveness will make them more desirable, which will push the impetus to design improvements. Let's look at what makes them better.
1. Reliability (and therefore logistics): Some modern enthusiasts for flintlocks claim they are extremely reliable, but records from the period show that the misfire rate was very high - some say one-in-seven, an Austrian Army study showed 15-20% in normal battlefield conditions and up to 50% in rain etc. This is for flintlocks - the previous methods such as matchlock, wheel-lock were less reliable and more resource-intensive. With the Spark ignition method, misfires will only occur if the main charge is so wet that it cannot be ignited. This has a benefit to logistics in two ways: 100% of the powder taken on campaign will go boom as desired and there are no fiddly trigger mechanisms to be broken and need replacing. Which leads to:
2. Cheaper and easier to manufacture: A firearm no longer needs a carefully drilled hole for the powder trail for ignition from the pan to the chamber, it no longer needs a spring-loaded trigger mechanism with carefully placed jaws to hold a flint - each firearm is now a metal tube attached to a wooden stock. Which means that it is cheaper to equip an army with them. While this is the simplest firearm, as specified in the question, it is more effective as the metal tube is manufactured better, especially once rifling is included.
3. Faster to reload: Armies will be able to get repeated volleys away faster. They still need to reload with powder and then ram down a bullet and patch, but there is no longer any messing around with priming the pan.
4. More accurate: With many pre-cartridge firearms, soldiers would aim, then turn their head away the instant before squeezing the trigger in order to avoid getting burns to their eyes from the ignition of the powder in the pan. (Which goes some way to explaining how short range volleys were more survivable than one might have expected otherwise.) With no powder in the pan required, soldiers can keep aiming and mutter the invocation for their Spark as part of their breathing routine as they shoot, significantly increasing their accuracy.
The combination of the above points will make firearms far more effective from the moment they are first introduced, which will in turn make it a far better investment to work on developing improvements such as sights, rifled barrels, more consistent gunpowder etc. Also note that the Spark spell would have a lesser impact on improving both land and naval artillery, as the need to cool down the barrel of a cannon in between shots would make the increase in rate of fire negligible.
**Possibly unintended consequences**
The ability to Spark through metal and presumably other substances may have issues if control is difficult to achieve and/or suicidal opponents are encountered. The "one metre from the mouth" limit prevents deliberate widespread battlefield "jamming", but it should be noted that every person with a pre-industrial rifle will also have a powder horn or the equivalent, which is the equivalent of a grenade sitting against their body. A recruit with poor control who is shoulder-to-shoulder with his fellow soldiers could conceivably detonate not only his own powder horn but those of the soldiers to either side in one fatal mistake. Similarly, an apparently-dead-but-actually-still-dying enemy on the losing side could, with his last breath, detonate the powder horns of one or two soldiers on the winning side as they advance across his body.
[Answer]
**I don't believe anything would be different in terms of *advancement***
It might be uber cool to cast Spark! to ignite your firearm, but it has several limitations — and one is, IMO, a doozy.
1. First, the use of magic with a firearm is splitting concentration. From the perspective of real firearm use (which we need to consider if we're going to answer the question, "how would they develop if...") you're focused on your target and your focused on your weapon. Now you're *also* focused on the magic.
2. It's slow. The time required to invoke Spark! will always be slower than the time required to pull a trigger. Even if we go back to the earliest guns. Anyone with a trigger-activated gun will have an advantage over anyone using a magic-activated gun. It won't take long for everyone to have a triggered weapon.
3. Here's the doozy. *The incantation can be heard.* Whether your hunting or a soldier in the military, the sound of the incantation will always precede the ignition of the powder. Generalizing, one can only hear the report of a rifle before dying when shot from a great distance. In most cases, you either never hear the shot or, more to the point, *you can't react to it.* Enter the incantation, where every target not made of bottles, cans, or wood will hear you speaking before the bullet is flying and have a chance to react. That gives a good advantage to the prey when hunting and a *substantial* advantage to an enemy soldier who's opted for the much more stealthy triggered weapon.
Now... if the incantation for Spark! was nothing more than an unbelievably quick and an equally unbelievably soft click of your tongue.... Can you create the magical version of a hot-key?
**Conclusion**
* I can believe a series of magic-activated firearms would exist, but somewhat as a novelty. The aristocracy would love them. They'd be seen at gun ranges.
* But I believe that the advantages of a trigger-activated firearm would make them preferred by the military, for hunting, and for personal security. That's 99% of the firearm market.
**Alternative**
From a certain point of view, an incantation like Spark! would represent the *least* a magician could do or, said another way, would represent the smallest change in the operation of a firearm. Is that useful?
What makes a firearm deadly is its ability to accurately direct the projectile. If you don't have something like Lightning Bolt! that "automatically" hits its target, then it makes more sense to replace both the trigger *and the powder.* Rather than casting Spark!, you want to cast Bang! All three issues mentioned above technically still exist, but now what you have is something...
1. Is inexpensive. It's just a well-decorated tube (OK, it's more than that, but you get my point),
2. Is trivial to maintain,
3. That does ***not*** depend on plentiful dry powder, patches, etc., and...
4. That is *much simpler* to load (and you can do it in a thunderous downpour!).
I'd recommend that you modify a world rule to minimize the sound of the incantation, but...
All those advantages weigh well enough against the disadvantages that my suspension of disbelief feels like it's happily eating pizza and drinking a cold soda.
[Answer]
**Blowpipes/Blowguns.**
They've been around for quite some time here on earth as well, and it wouldn't be too far of a stretch to adapt them into a form of firearm if your citizens are able to cast a spark from their mouths.
I think the biggest issues might be recoil, and keeping any expanding gasses from blowing back out of the end that faces their mouth. Though if they can cast the spell in a one-meter radius away from their bodies, they might be able to get around that issue! Or if they engineer some sort of valve that shuts off as soon as whatever charge is inside the pipe ignites, which wouldn't be too complicated.
They also might need to make them out of sturdier materials as well though.
[](https://i.stack.imgur.com/xnvJD.png)
[Answer]
In close quarters, can one put a spark in your eye? Heart? Head?
Is that survivable?
Might be an interesting addition to the second act of the classic battles, when two sides have exchanged a few volleys of balls and the muskets became clubs with knives on the end (bayonets) and so the distance to opponent is close enough for the one-meter range.
Otherwise, in some hide-and-seek thrills, nowadays characters often toss a bit of debris to make a sound which makes the seeker momentarily look elsewhere (and the character has a better chance to ambush or run away). Can a spark be used like that (if the delay and spell spoken volume is negligible)?
Conversely, can a delayed spark be set? e.g. you run through a corridor, hide in a random room and make a "proximity spark" in advance (less limit on the spoken voice giving away your position) that would go off once someone comes through the door, so then you make your jump on the distracted intruder...
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A scene am writing takes place in Summer in the Artic. The character is swimming underwater, under the ice (imagine a small iceberg).
Above her a large bubble of air has formed. Never mind what formed it. It remained locked there because of the uneven shape of the ice bottom.
The swimmer is about 10-20 meters underwater. The ice bottom and bubble of air is 4-5 meters above her. The air bubble is about 4 cubic meters. Outside is daylight and the sun well above the horizon. The light comes sideways into the water and under the blue ice which is very thick (several meters). The bubble may be near the border of the iceberg.
The swimmer is wearing future snorkeling gear (no air tanks) with full face mask. Warmed suit to resist the cold water better.
**Would the swimmer be able to see the air bubble from beneath?**
How else could she detect it if not?
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> Would the swimmer be able to see the air bubble from beneath?
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**Only in very specific circumstances** (which your setup *seems* to negate).
Ordinarily (been there, done *almost* that), you won't see any specific difference from below.
Except in this one case, that I can vouch for: if you release bubbles, and you're under the ice with a reasonable light source with you, you will see your bubbles "falling upwards" on the lower surface of the ice. If they hit a larger bubble of air trapped underneath, delimiting a larger area of the lower surface, the bubbles will merge with it and the whole area will start rippling and sending back the light in a fractured way. That is sure to catch your eye, **but** if your future scuba does not release bubbles, or the swimmer is not looking exactly upwards, they won't notice anything.
If you are close enough to the trapped air sac that you look at it at a low enough angle (below the *critical angle*), then Snell's Law comes into play and the air will appear as a mirror. That effect is unmistakable. But **you need to view the bubble under the appropriate angle**, which means being close to its surface (or looking at a distant trapped sac):
[](https://i.stack.imgur.com/uf4lo.png)
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I suspect that under 15+ meter of ice one won't be able to see much with naked eye.
[This page](https://mymodernmet.com/iceberg-underwater-tobias-friedrich/) shows very nice pictures of what it looks like to swim under an iceberg
[](https://i.stack.imgur.com/MAftO.jpg)
Notice that when there is no free water surface available, the water is much more dark, and there we see small ice blocks roaming the water surface.
The swimmer might be able to see something from very close when using artificial lights (underwater lights do not have a very long range), but would just notice the air/water interface as being rather flat when compared to the iceberg surface and probably reflective and metal like if seen from the right angle.
A possible way to detect air pockets would be using sonar: the reflectivity of the air/water interface is different from the ice/water interface, due to the larger difference in density.
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**Air bubbles are reflective. Ice is not.**
[](https://i.stack.imgur.com/bOvUm.jpg)
<https://weather.com/photos/news/underwater-ice-sheet-hockey-austria-tobias-friedrich>
These divers have left bubbles under the lake ice. The bubbles are reflective. You can see them shimmering above the divers.
There is an even better photo here:
<https://www.alamy.com/stock-photo-reflection-in-air-bubbles-made-by-divers-under-surface-of-the-ice-86744148.html>
Air bubbles in water look like puddles of liquid mercury. The surfaces are reflective and metallic appearing. Ice does not have that mirror look.
Your diver would see the reflective shimmer of the bubble. It will look different from the ice but it might not immediately be clear to her what she is looking at if she has not seen it before.
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I have an idea for an energy source for a colony on a cold world with not enough solar power. Is my idea workable, or is it debunked as perpetual motion machine? Here is the set-up and my plan:
**Scenario**: Humanity has made giant steps since the landing on the moon. Better and faster space-travel allows travelers to reach Saturn and its moons in a month or less, and space colonies are emerging on Saturn's moons. One of those moons is Titan. Wind power is the main power source, since nuclear fusion has not yet been mastered, and solar energy is too scarce.
**The problem**: One of the colonies was established, out of necessity, in a location with little wind flow. As there is no other source of energy, and fusion has not yet been mastered, the colonists had to find an alternative.
**The geography**: The area is classified as a "desert": The air is dry. Yet, there is a river that flows, albeit too slowly for hydro-electric power. (The river is made of Methane, not water, and the humid air would contain Methane vapor). A similar set-up is the Red-Sea which crosses the rift between the Sahara and Arabian Peninsula: Although there is plenty of water, the air in the desert is dry.
**The heat engine**: The heat engine all by itself would be of no use, as no available heat sources were found in that location. In addition, coupling the engine to a heat pump which creates a heat gradient will not work either. That would classify the system as a perpetual motion machine which violates the second law of thermodynamics.
**The work-around**: The designer has realized the air is dry. If a heat pump will not work, then what about an evaporative cooler which takes Methane from the river? A cooler will use far less energy than a heat pump for the same cooling effect. It will create a heat gradient that may be sufficient to drive the heat engine. The heat engine will provide energy to drive the cooler and (hopefully) excess energy for the colony.
**The energy source**: In an *enclosed* system comprising a fluid and "dry" air above it, the fluid eventually evaporates until it fills the air above it and reaches the vapor pressure unique to each fluid, pressure and temperature. The overall temperature goes down because some heat becomes "latent heat" which made some fluid remain as vapor. Because all such systems end-up doing this, I can assume that a system with a fluid and dry air above it has some potential energy. At vapor pressure, the system is in equilibrium and has no potential energy, therefore energy is no longer extracted. On the other hand, the climatic set-up around the colony *is not an enclosed system*: Constant dry air is provided by the weather system. The river flows from a humid into a dry location. In other words, the set-up is still powered by the weather system.
**Will my design solve the colony's energy crisis?**
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Enthalpy of vaporization of methane is very low - 5 times less than that of water. You will get about 5 kJ from 1 kg of methane. Even with low temperatures (about 100K ) "boost" to efficiency, it would not be above ~25-30%. So only 1.5kJ of energy from kg of evaporating methane would go to colony.
One household (about 2-4 people) here on Earth need about 10 kWt\*h ~ 3.5 MJ of eneregy per day. On Titan we can multiply it by 10 (heating, oxygen, science). So by this rough approximation you need to evaporate 30t of methan per "hosehold" or ~10t (~20 m^3) per person in a day. That will produce 200-2000 millons m^3 of "wet air" per person per day or about 2-20 L/s.
Thats a lot, but doable.
But there is a catch: to make this scheme work you need a place with strong and costant winds to remove this huge amounts of wet air from a vast cooling fields. But this wind would be a more convinient and powerfull source of energy by itself. It would be times more efficient to build wind generators in this area. And if place is bad for wind generators - evaporation would not work (for long) since "wet air" will accumulate and prevent futher evaporation. Thats why nobody uses this scheme here, on Earth.
P.S. And you have to have a realy good explanation why this river does not evaporate by itself at first place. Most rivers in Sahara (there are some!) do not last for long (both in distance and time) becase of that.
P.P.S. all approximations are wild!
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If spacecraft can reach Saturn in a month, then you have some sort of energy source which renders the problem moot (even if it is not fusion as per your OP, it has equal or greater energy density in order to propel spacecraft that quickly). The craft can orbit Titan and beam energy down via microwaves or lasers focused on cooperative power targets if you handwavium requires that your system remain in space (i.e. artificial back hole drive).
As for actually operating on Titan, most conventional heat engines will work far more efficiently due to the extreme cold temperatures. The Carnot equation depends on the temperature differential between the "hot" and "cold" reservoir, and the greater the differential the higher the efficiency. Since on Earth the "cold" side is atmospheric or room temperature, the only way to really boost efficiency is to run the hot end at the maximum temperatures the materials can handle. On Titan , the "cold" side is cryogenic, where ice is as hard as granite and things like methane are liquids in the open, so the temperature differential is far higher.
[](https://i.stack.imgur.com/ZMihC.png)
In simple terms, a heat engine on Earth is about 25% efficient (1- 300k/400k; 1-3/4 = .25) while the same engine on Titan is about 75% efficient (1-100k/400k; 1-1/4 = .75)
Issac Arthur has a very interesting (if long) [video](https://www.youtube.com/watch?v=HdpRxGjtCo0) where he describes how this fundamental principle could make Titan the economic hub of the outer Solar System since the cold temperatures and the presence of an atmosphere (which makes heat rejection far easier than radiation alone) makes industrial processes using the Carnot cycle far more efficient. This also translates to far more efficient computing as well. His key takeaway is that people will not actually live on Titan, but simply live in orbit and supervise the work of the machines below.
So the real answer to your question is there is no need to create strange contraptions on Titan to extract energy from the local environment. Humans have not done that on an industrial scale since the Industrial revolution, and there is no need to do so in space either. The sort of energy needed to travel across interplanetary distances at high speed already means there is a surplus of energy available, and Titan provides a convenient "cold sink" for high efficiency industrial and computing operations to take place.
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It sounds like you're trying to reinvent the [Stirling Engine](https://en.wikipedia.org/wiki/Stirling_engine). If so, then yes it will work.
To operate the stirling engine merely requires a greater temperature differential than is ambient in the environment. As soon as that occurs the engine will run and energy can be extracted from the system.
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As other answers have said, given enough resources (Methane), your proposed heat engine could work, however I wonder if there could be a more elegant design - especially considering that humans have mastered travel through the solar system.
Since, in your world, humans are now expanding to other planets and moons I think it likely that through the development process engineers would be working on ways to either encapsulate energy for when it is scarce or ways to transmit energy long distances. Since humans are traveling around the solar system in months and spread throughout it there would likely be some sort of infrastructure in place for cargo transport, etc.
If there is no reason that the colony has to be 100% self-sufficient (the energy **has** to come from Titan), you could take advantage of these cargo routes to transport either fuel or large batteries to colonies with scarce energy along with regular resupply missions. This could be one solution, but the next one I like better:
**Wireless Solar Energy Transmission**
So, you're on Titan. It's cold, dark, full of methane, and you need energy... bad. Luckily the engineers have been working on solutions to maintain a flow of energy to all the colonies.
In a close orbit to the sun, you have an array of large solar collection devices. The concentrated energy is used to generate a laser of a specific wavelength that transmits energy to satellite devices spaced along routes through the solar system. Mirrors/Optic systems could create a constantly unobstructed pathway to all of the satellites as they move through their orbit (or in stationary orbit around another planet). After passing through a relay of these satellite devices, the laser ends its journey at a receiver on the destination planet/moon.
Disadvantages of a laser system such as energy loss through atmosphere wouldn't be an issue transmitting to Titan, but you would certainly not get all of the energy back. This would require a receiver on Titan many hundreds of meters across, and a substantial battery to store the energy as it comes in. Ideally, an unmanned mission would prepare the required infrastructure so that the colonists arrive with several months worth of energy already having been transmitted and stored in the battery.
Similar energy transfer can be done with Microwaves, and to my knowledge the energy conservation is much more effective with Microwaves since you aren't losing so much energy to visible light. Current systems can achieve up to 85% efficiency. Microwave however runs the risk of RF interference (which could be a problem unless the system is positioned away from communication channels) and the receiver would have to be larger than that of a laser.
Here are some stats on current wireless space-solar power systems for reference:
[](https://i.stack.imgur.com/M2sVo.jpg)
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The basic idea is that a small group of people, that were infected by the virus but managed to survive, has their hair colour changed to white and their eye colour changed to green. Said traits would then be passed on to future generations.
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Some context info (changeable if needed):
1 The affected group is ethnically pure = physical traits vary less (think modern-day Japan).
2 Eye colour has changed from blue to green; if not green then gray.
3 These traits aren't dominant (this comes from my very crude understanding of genetics); a kid would need both of his/her parents to be affected by the virus to be *fully* white-haired/green-eyed.
4 The virus has a kill-rate of 90%.
5 The world is comparable to Europe's late Medieval Era.
6 There's no magic.
(Edited):
7 The virus is transmitted through the air.
8 It is naturally occurring.
[Answer]
### (1) Ebola
* Changed one doctor's eye color [from blue to green](https://www.iflscience.com/health-and-medicine/ebola-changed-survivors-eye-colour-blue-green/). Although in this specific case his eye color did change back, the article notes:
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> Though it is quite rare for eye color to change so dramatically, this does happen from time to time as a result of viral infections and is usually permanent. Changes in color are usually due to the viral infection damaging pigmented cells in the iris. Following treatment, however, Crozier’s eye returned to normal, though it remains unclear why.
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* There are links between viral infections and [graying hair color](https://www.insidescience.org/news/link-between-gray-hair-and-viral-infections)
* Had a [kill rate as high as 89% kill rate in the Democratic Republic of the Congo](http://emedicine.medscape.com/article/216288-overview)
* Although Ebola doesn't pass on genetically, in a medieval-type world without proper sanitation (or even awareness of biotics) it could easily spread to children, especially if one or both parents had the disease.
* If your story included a mutated form of Ebola that attached to people genetically, the other criteria make sense.
### (2) Shingles
* [Shingles](https://en.wikipedia.org/wiki/Shingles) is a crazy virus (a form of herpes) that often lays [dormant for many years](https://www.medicalnewstoday.com/articles/154912.php)
* can cause [severe hearing loss or blindness](https://www.mayoclinic.org/diseases-conditions/ramsay-hunt-syndrome/symptoms-causes/syc-20351783). In rare cases, can lead to death
* again, by default it doesn't pass on genetically, but (a) is part of the same virus [that causes chickenpox](https://kidshealth.org/en/parents/shingles.html), which was considered "norm" for children due to its prevalence until vaccines were made for it. And (b) a mutated form of Shingles would not be difficult to image, one that attached (passively) to children during insemination, but laid dormant.
* although mortality rates of shingles is low, a mutated form could be more deadly. Given its tendency to lay dormant without detection or activation for many years, it's unlikely a medieval-type society would be able to prevent it.
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There are lots of things that can depigment hair and skin. Some drugs can do it, but that is reversible. Age of course can do it. [Vitiligo](https://en.wikipedia.org/wiki/Vitiligo) is an autoimmune condition; affected skin loses pigment and hair coming from that skin can be white. It is possible to develop vitiligo because you have melanoma - an immune attack on the pigmented tumor cells also attacks pigmented non tumor cells. I do not know (until just now) of any virus which leaves white scars.
Iris depigmentation is rare. Drugs that depigment hair and skin don't affect the iris, nor does age (not counting arcus senilis) Vitiligo does not usually affect the iris. But viral infection apparently can cause depigmentation of the iris.
[Bilateral acute depigmentation of the iris: report of 26 new cases and four-year follow-up of two patients.](https://www.aaojournal.org/article/S0161-6420(09)00179-1/fulltext)
[](https://i.stack.imgur.com/OCDHL.png)
<https://aibolita.com/eye-diseases/38504-gregory-ostrow-md.html>
As I understand it this is not an immune attack on the pigment cells but direct infection and destruction of those cells by virus.
So yes, **your virus could cause lasting pigment change.**. Have the melanocytes be one of the targets of this virus such that they are destroyed throughout the body. Or have an immune attack on the virus that hits melanocytes. Or both.
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# Genetically transferred virus
User cegfault did a good job showing that Ebola would be a good candidate virus for killing 90% of the infected and causing grey hair and green eyes. But Ebola is not passed on genetically. BUT there are ways viruses could be passed on genetically. Here's how:
Retroviruses insert themselves into the DNA of our cells, but we don't pass on most cells to our children (e.g. chickenpox lives in nerve cells not in sperm/eggs). However, very rarely, viruses do get into our sex cells and so get passed on (when I mean rarely I mean back when our ancestors were lemurs). [We know this has happened before](https://www.nytimes.com/2017/10/04/science/ancient-viruses-dna-genome.html) and some scientists think it may be behind multiple sclerosis and [schizophrenia](http://discovermagazine.com/2010/jun/03-the-insanity-virus) (this is a super cool theory by the way, basically this virus can get activated during an illness and depending on how our body responds we can get MS or schizophrenia). Now its believed that these viruses accidentally ended up in that ancestor's sperm/egg cells but we could imagine a virus that preferentially inserted its DNA into sperm/eggs just like chickenpox hangs out in nerve cells.
Ok great, now we've got a virus in the parents sperm/egg DNA but still need to inherit that virus from both parents to have the change in hair and eye color. Well, if we inherit one "healthy" side of DNA that DNA continues to make the correct eye color, perhaps even compensating for the "bad" DNA (just like how carriers of albinism aren't lighter skinned but if they have children with another carrier 25% of the children will be albino). The only problem so far is that Ebola is not a retrovirus so cant insert itself into your cells (it only uses RNA not DNA). But perhaps a [satellite virus could perform horizontal gene transfer between viruses](https://en.wikipedia.org/wiki/Horizontal_gene_transfer) and a retrovirus could obtain those attributes of Ebola that we are interested in. Voila, now you can get the virus from your parents or from the air (and once you get it from the air it inserts itself into your sex cells and you pass it on to your kids). Now why doesn't the virus from your mum's cells infect the cells with your dad's DNA? Perhaps the cells only insert their DNA into the sex cells.
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A genetically engineered retrovirus is fully capable of changing genetic traits, including eye and hair colour, but as your setting is medieval, I doubt anyone is engineering viruses.
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It is certainly possible for a virus to change hair or eye color. (See other answers for examples. I can also offer the example of a friend whose hair color changed permanently after chemotherapy.)
It is certainly possible for a virus to worm its way into our DNA and cause heritable mutations; a big chunk of our DNA is viral insertions.
What seems less plausible is a virus that causes inheritable changes to visible characteristics. Your virus needs to be pretty effective to hit body cells as well as germ cells.
*Darwin's Radio*, from maybe 20 years ago, explored the effects on society when people started giving birth to children who were... different.
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Assume a world in a distant (2100+) future. Assume an exponential construction rate (1, 2, 4, 8 etc.) in skyhooks/time. Assume significant solar system exploration and industrialization. Assume shykooks and full space elevators are possible, strong enough and stable. Assume several orders of energy availability (SBPS), Assume sophisticated transhumans, including significantly higher intelligence. Assume no distinctive singularity. Assume nonstop economic growth since 2018.
Can an equatorial "forest" of thousands of space elevators be used to gather industrial (mostly computational) waste heat off world, up the gravity well and funnel it out with 'thousands kilometers long' radiator fins? Would this make sense or would this be a self-defeating proposal in one or more steps? Is this still hard science or "way too much handwavium"?
Context - writing a series of "far out" lateral short stories about 'the earth a century from now' and taking basic premises, fairly hard science to the most absurd conclusions I can do.
Suggestions for this thesis/premise highly appreciated.
*Love you all*
Edit: Server farms outputting waste heat are already a major problem. Merely bitcoin transactions and mining can wreck climate change goals, - by itself - . I merely explain HOW such absurd waste heat is generated, and ask "can we get rid of extreme waste heat generated ON the planet, by traversing it up space elevators, creating large radiator fins in orbit and radiating the heat away.
Yes, I misread the "hard science" tag as "hard science fiction" and will alter that.
So ... why do I ask this question?
It's because I want to use this particular idea for a short set of stories I am writing. I already created a rough outline of these stories. A guy from Belgium is making a documentary about me, and I made some bold claims about the seemingly absurd exponentials in industrial and civilizational growth in the next century.
My premise is "what if we have non-stop economic growth ? What if capitalism does not break? What if we do not have major catastrophic events or nuclear wars? What if we take all these premises to absurd end conclusions?
Maybe my question should be "are there OTHER ways to get rid of absurd waste heat produced by a century of non stop exponential growth rates on earth" ?
Yes, I assume there will be the same exponential growth rates in space as well. So at the same time as earth gets a century of on average, say 3% annual growth? That would mean a shift from using about 15 terawatt to just under, what 300 terawatt?
What other ways than radiation means can be use to burn that heat away without cooking off the oceans and atmosphere?
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1. Space elevators do not have to sit above the equator. See, for example, Blaise Gassend, “[Non-Equatorial Uniform-Stress Space Elevator](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.560.1934&rep=rep1&type=pdf)”, 3rd Annual International Space Elevator Conference, Washington DC, June 20, 2004 (or [his web page](http://gassend.net/spaceelevator/non-equatorial/)); or consider the "forked" design popularized in Kim Stanley Robinson [*Mars*](https://en.wikipedia.org/wiki/Mars_trilogy) trilogy.
2. You don't say what a "forest" means. Let's say we want to use 10,000 space elevators.
3. You don't say how much waste heat you want to radiate into outer space. Assuming energy consumption grows at the same rate as from 2010 to 2015, that will be 1,420,000 TWh/year, or 162 TW.
Justification: the Wikipedia article on [world energy consumption](https://en.wikipedia.org/wiki/World_energy_consumption) gives the total amount of primary energy supply in 2010 as 150,000 TWh, and in 2015 as 170,000 TWh; thus the increase from 2010 to 2015 was 2.53% per year; keeping the same rate of increase, in 2100 mankind will use a primary energy supply of 1,420,000 TWh.
4. Since we said we'll use 10,000 radiators, this means that each radiator needs to radiate about 16 GW. That's a *big* radiator.
5. Now the problem bifurcates. On one hand, we need to *gather* those 16 GW to the radiator; on the other hand, we need to *radiate* them into outer space.
6. How do we *gather* 16 GW, presumably from the ocean or from the air? I don't have the foggiest idea.
(a) We need to suck this amount of heat as uniformly as possible from the entire area serviced by the radiator. Since we said that we use 10,000 radiators, each of them needs to service about 50,000 square kilometers (20,000 square miles). A dystopian landscape filled with finned heat exchangers comes to mind.
(b) Once gathered, this heat must be moved to the radiator.
(c) Presumably, the heat will be gathered in the form of some hot fluid. Since the [coefficient of performance](https://en.wikipedia.org/wiki/Coefficient_of_performance) decreases as the temperature differential increases, it would be rather impractical to heat the fluid to more than 300 °C (572 °F) or so. (Assuming that the heat is gathered from room temperature, at 300 °C the maximum theoretical coefficient of performance is 2, meaning that we need to spend at least one watt for every watt of heat extracted.)
(d) Assuming that the working fluid is water, how much water is that? The [heat capacity](https://en.wikipedia.org/wiki/Heat_capacity) of water is 4186 J per kilogram kelvin (higher than any other common substance); to move 16 GW of heat in the form of water at 300 °C we will need a flow of about 13 cubic meters / second; that's a sizeable river. (For comparison, the Thames discharges about 65 cubic meters per second, and is navigable by ocean-going ships.) The total flow of water for all 10,000 radiators will be 130,000 cubic meters/second, about 50 times the discharge of the Nile or two thirds of the discharge of the Amazon.
For fun, the water will be at a pressure of about 90 atmospheres. Size the pipes accordingly.
7. [Black body radiation](https://en.wikipedia.org/wiki/Black-body_radiation) power is about 5.67E-8 W⋅m−2⋅K−4; to radiate 16 GW at 600 K, each radiator will need about 2 million square meters (about 0.85 square miles) of radiating surface; the radiation will be in the form of infrared light with a peak at a wavelength of 4830 nm.
8. In the grand scheme of things, how much power is 162 TW? The Earth receives about 174 PW of energy from the Sun; 162 TW is about 0.1% of that, which is about the same as the difference between the maximum and the minimum of solar energy hitting Earth during each [solar cycle](https://en.wikipedia.org/wiki/Solar_cycle).
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## No need for elevators: Pump it out on beams of light
You can pump heat off the planet simply by beaming it into space via light emitters. Infrared light is the most obvious, but spectral light will suffice. The emitters can be on the ground as long as there isn't cloud cover. By "as long as" I mean you may be able to simply wait until clouds are gone.
You can also run this day and night, but by day there's a "problem". In another question I propose using pumped storage to use hydro dams to store wind-generated electricity. And I realized that it would be fundamentally stupid to back-pump at the same time the dam's turbines are generating electricity. Just send the wind power to the customer and generate less at the dam; it's all a *wash transaction*. **The very same physics apply to light-pumping by daylight**. It is stupid to send light energy *up* whilst the Sun is sending light energy *down*.
## Simply reflect solar energy
It's cheaper. Here you use whatever technology is easiest: orbital solar shades, paint roofs white (my paint supplier reports several white-ish paints with over 90% albedo), help deserts radiate, etc. For instance, in Star Wars: The Last Jedi, the planet with red soil just millimeters under its white surface was a natural (or artificial?) case of this.
This doesn't do anything to reduce your industrial heat, but it sheds natural heat, which is a wash.
Solar energy can help too. Solar panels make two kinds of heat, first their albedo is much worse than the natural earth they replace, so almost all the solar energy that isn't turned into electricity becomes heat at the panel. Second they prevent the underlying earth from radiating heat in its normal way. However they prevent electricity from being made in ways that could create a lot more heat and things like CO2 which then have knock-on effects to warming. The math is a little complicated, but turning the unwanted natural radiation into electricity may be a win.
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Sure, though it's an amazingly inefficient way to do it!
To make it work you need technology to transfer heat up the beanstalk, and then you need to dump that heat into radiators pointed out into space.
As far as transferring heat goes, convection is probably the most efficient. Think of it as basically a giant air conditioner with the Earth side containing coils filled with fluid to be heated (this is the cool fluid which came down from space). The heated fluid is then pumped up the beanstalk to the heat dumping side where the hot fluid transfers its heat to some external environment.
You'd effectively have an up pipe and a down pipe and the cost of circulating the working fluid would be only to replace friction losses, since the energy to lift the hot fluid up to space is balanced by the gravitational energy released as the cooled fluid descends.
It's hard to say what the right fluid would be -- that's a very technical engineering tradeoff -- but it's likely to be a liquid rather than a gas because a gas would require much, much larger pipes which is very costly in terms of beanstalk infrastructure.
The radiators would probably be a lot like the [standard radiators we use today](https://en.wikipedia.org/wiki/Spacecraft_thermal_control) to cool spacecraft. One side is black (which radiates most efficiently) and points to empty space, while the other side (which would face the Earth or Sun) would be silver so as not to absorb radiation.
Could radiators actually remove enough heat to matter? If you look at the [Earth's energy budget](https://en.wikipedia.org/wiki/Earth%27s_energy_budget), the Earth absorbs around 240 W/m2 of sunlight and thus must radiate slightly more than that back into space. (There's some heat leakage from the Earth's interior.) Earth's current total electricity production is about 25,000 TW. Divided up by the surface of the Earth, that's .005 W/m2. So human electricity production is .00002 of the Earth's radiating capacity. So space radiators of area .00002 of the Earth's area will handle it all. That's about 4000 square miles. That's not particularly large given the space elevator technology postulated.
Other than the space elevators, there's no new technology needed. (Though the scale is daunting.)
But it's still a magnificently inefficient and hugely costly way to cool the Earth!
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Humans already exterminated more than 50 % of wild vertebrates individuals since 1970 [1](https://www.theguardian.com/environment/2014/sep/29/earth-lost-50-wildlife-in-40-years-wwf), [2](https://www.bbc.com/news/science-environment-37775622).
I was wondering if it is possible to **wipe out the remaining 50 % in less than a year** ?
Note that, in this (alternative?) reality, Humans decide to spare no effort in this endeavour and desire to safeguard domestic species.
*Bonus question : Is the Earth still liveable after the extermination ?*
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No, it’s not within our power to kill all the [deep sea fish](https://en.m.wikipedia.org/wiki/Deep_sea_fish) within a year. Vertebrates that we kill higher up in the ocean will just fall to the sea bed and become food for them. And even if we could stop any organic matter from falling to the ocean floor, some vertebrates would still survive around geothermal vents.
[Answer]
**No**
Humans have been trying to get rats to stop living off our largesse for millennia. Nothing has worked so far. If the survival of the human race meant we needed to no-fooling kill them all, we might be able to figure out something out. Eventually. But we are not going to develop and test new ways of killing off our rat problem, then deploy them everywhere around the globe (including in the poorest slums of the country with the worst GDP), and accomplish all of this in less than twelve months.
[Answer]
Concerning your bonus question: **probably not**.
In some parts of the world (especially Africa), giand herds of herbivores forage and eat literally every single blade of grass, leaving behind tons of manure that fertilize the soil for the next generation of grass. Take these herds away and the circle of life stagnates. Young plants are suffocated beneath old grass and one spark sets the whole mess ablaze.
Same in the water: without herbivore fish, reptiles and marine mammals like sea cows to eliminate tons of algea and seaweed, many rivers and coast lines would become impossible to cultivate for domesticated aminals (fish farms).
This may not sound *too bad* at first, considering that humans wanted to get rid of all wildlife, but it could influence the locale climate and remaining wildlife quite severily.
* Noone wants bushfire to endanger the lifes of humans and domesticated animals
* Lack of vegetation results in lack of rain, causing draughts and crop failure
* If pests and parasites (like mosquitos) can't feed on wild animals, they will turn to domesticated animals, causing epidemics
* Invertabrates like jellyfish, insects, snails and octopuses will increase explosively, with unforseeable consequences
[Answer]
**[2,3,7,8-Tetrachlorodibenzodioxin](https://en.wikipedia.org/wiki/2,3,7,8-Tetrachlorodibenzodioxin), also known as TCDD, a part of [Agent Orange](https://en.wikipedia.org/wiki/Agent_Orange)**
destroys the
**Aryl hydrocarbon receptor**
vertebrates have, killing them if they consumed enough.
so if your humans really want to wipe out all wild vertebrates, they just have to spray everything with tons of TCDD, killing all vertebrates on land, and then pour it into the oceans, killing all vertebrates there.
it is solid, you have to solve it in something else ([chloroform](https://en.wikipedia.org/wiki/Chloroform)) to be able to spray it properly. but because it is not a gas, it is easy to keep citys save. (of course you have to kill rats etc per hand)
so **humanity could kill all non domesticated vertebrates**.
but **earth stays liveable after that** since [some crops](https://www.foodrenegade.com/gmo-agent-orange-resistant-soy-corn/) sustain TCDD.
] |
[Question]
[
I am working with a fantasy setting wherein a society of feudal humans launches a crusade against a continent largely controlled by elves. Though the human society is not entirely without its own magical resources, the primary source of its military strength is in fielding large numbers of heavily armored Knights. It's basically late 14th century France, with bad infantry and mediocre skirmishers.
The Elves in this setting are on their home turf and have large numbers of truly top notch skirmishers in the form of crossbow wielding marksmen and mounted archers.
What would be the best way for the humans to go about combating a force such as this? I know that guerilla campaigns are frequently unsuccessful, but most of the information I can find about combating such tactics are for modern armies. **How would a medieval army go about suppressing a force of determined guerillas?**
*Edit* I have been asked for a fuller explanation of the scenario several times now, so here goes.
*The situation:* A large feudal nation of humans has launched a crusade against a distant continent ruled by hostile elves. These elves have operated like the Barbary Pirates since time out of mind and a variety of factors have finally motivated the humans to attempt to put a stop to all this raiding and slaving. The crusaders aim to devastate the elvish homeland, raze one of their major cities, destroy their naval power and rescue enslaved citizens.
To this end the King of the human nation has declared a crusade. All major lords of his nation are expected to send forces if not attend themselves. Due to his prestige and widespread sympathy for this cause independent knights from various foreign powers have also joined, inflating the proportion of knights vs footmen in the crusading army.
The voyage from the human continent to the elvish is quite long, and can take from a month to a month and half depending on weather.
On a neighboring continent to the hostile elves, about a week to a week and a half away, a nation of far more friendly elves exists. Though they are not sending troops, they approve of the cause and have agreed to sell them supplies at discount, provide aid at sea and grant them certan guides. These other elves will not allow them to land on their continent however. Hence their supply lines are shorter than their reinforcment lines.
Neither side is willing to negotiate with the other in any meaningful way.
*The Land:* A long narrow continent in the northern hemisphere. It is relatively small in the south, 100 -150 miles across, fanning out into a wide land further north till it hits polar ice. Much of it is a rocky wasteland, though coniferous forests run up and down the center of the continent. Between these and the mountains the land is quite rugged. The besieged city in question lies roughly in the center of this southern portion about 50 miles inland from where the crusaders have landed. This is the southernmost city of the elves and is relatively isolated, cut off by mountain ranges from the others. It sits in the middle of the forest on the shore of a lake, which, by various rivers leads eventually to the sea.
*The Forces:* The Humans are a picture of 13th-14th century France with some magical elements. I will leave those out for the most part as they are rare enough to not dramatically impact the strategic picture.
Human Knights clad in plate and chain with heavily barded warhorses comprise the prime force of the nation. In one of the few widely available magical things they have going for them, their horses interbred with magical elven steeds in the past. They are larger on average than horses in real life, and can wear heavier armor while maintaining their stamina. Imagine that 4 out of 5 knights in the army is riding an abnormally intelligent Destrier the size of War Admiral. The foreign men at arms ride more normal Courcers and the like.
Accompanying the Knights and Men at Arms are an assortment of poorly trained peasant soldiers. They are accustomed to being deployed in battle to a static location, holding that area and letting the knights do most of the work. They are supported by longbowmen, who are quite good, but average out to mediocre in a fantasy setting. Around 1000 professional soldiers have come with the foreign knights, giving a little bit of backbone to the infantry.
Of finnal note on the humans I will mention something about their higher nobles. A very small number of the knights and higher Nobles in the army, including the King, have extended lifespans and superpowers a la Arthurian Legend/Orlando Furioso. Assassinating or sniping the highest leadership of the army is a dubious prospect at best even for the elves. At the highest levels of command the Peers of the King have supernatural levels of military experience. The King is around 130 years old, with some of the Peers being in the 200 to 300 year range.
The Elves in this setting are basically good at everything, but suffer from low numbers. They have superior infantry, cavalry, archers, the works, but not in high enough numbers to drive the crusade from the field in a single hammerblow unless conditions were optimal.
Their citizen militia, which is the bulk of their forces, is competitive with professional human soldiers, and they have large numbers of very good crossbowmen and horse archers.
The elvish professional soldiers are equipped with nearly weightless armor of similar strength to heavy steel plate. They have a full range of weaponry but prefer swords for close shipboard combat.
Elvish heavy cavalry are superior to human knights, riding the elvish steeds that the human steeds originally mixed with to become what they are now. Again however, there are so few that they would be quickly overwhelmed in most massed cavalry engagements.
*The Numbers:* I do not have concrete numbers for the forces involved here, however the nation is larger than France and like in the real crusades forces from multiple neighboring countries have arrived to assist. I will say 25,000 Men at Arms, and 80,000 Footmen. Lets then add in another 40,000 for workers, sailors, woodsmen, grooms ect.
The Elves are a bit trickier, they are on their home turf, but suffer from a low population compared to humans. Although their citizens can almost all fight, they cant mobilize all of them for obvious reasons. They also have a huge slave population which they have to keep under heavy guard at all times, especially when they are under siege. A slave revolt from within is to be expected at some point, but we will assume that it is suppressed with minimal elvish casualties.
Let's say a population of 300,000 elves of fighting age in the city and surrounding countryside. A fifth of those can be mobilized directly against the invaders. 20,000 within the city, 40,000 without.
Of these 60,000 lets say 10,000 are professional soldiers, the rest are citizen militia, generally superior to the human footmen, but inferior to knights. Lets put their cavalry force at 5,000 horse archers, and 1500 elvish knights.
[Answer]
Here comes the shortest answer of the all: just let them do as they would have doe anyways, but even more cruel. They will have to kill any elve they see, whether children, women or elders, burn villages, fields, and forests. They should at any cost avoid the mountain range, and instead should try to fight the battle on the rocky desert, as it is open field and should only move on after they have burned down woods before them. They should land on different locations around the continent instead of marching for a longer period through the country, and should later, when the elves are already hurt, cut one swath to the center, to conquer the hole continent.
[Answer]
1: You want your mounted knights to be arrowproof. Armor helps with that. A problem at Agincourt is that the horses were not arrowproof. Armor helps them too. Your end result: a [Cataphract](https://en.wikipedia.org/wiki/Cataphract).
[](https://i.stack.imgur.com/Losqo.jpg)
<https://www.researchgate.net/figure/Depiction-of-Iranian-type-cavalry-at-Dura-Europos-after-Robinson-1975-fig-190_fig54_323545452>
>
> The English word is derived from the Greek Kataphraktos, literally
> meaning "armored" or "completely enclosed". Historically, the
> cataphract was a very heavily armored horseman, with both the rider
> and steed draped from head to toe in scale armor, while typically
> wielding a kontos or lance as their weapon.
>
>
>
The Persian / Parthian cataphracts were pretty much invulnerable; certainly they would not succumb to a few measly arrows. So too your crusaders.
2: The elves will never close and do battle with these mounted knights. It would be suicide. They will harass them and harass them. The solution for the knights: do not fight the guerilla archers. Instead, destroy the countryside and the livelihood of the elves. This becomes a [**Chevauchée**](https://en.wikipedia.org/wiki/Chevauch%C3%A9e)
>
> A chevauchée was a raiding method of medieval
> warfare for weakening the enemy, primarily by burning and pillaging
> enemy territory in order to reduce the productivity of a region, as
> opposed to siege warfare or wars of conquest. The chevauchée could be
> used as a way of forcing an enemy to fight, or as a means of
> discrediting the enemy's government and detaching his subjects from
> their loyalty. This usually caused a massive flight of refugees to
> fortified towns and castles, which would be untouched by the
> chevauchée.
>
>
>
[](https://i.stack.imgur.com/baaVh.jpg)
<http://fighting-the-earth.leadr.msu.edu/shermans-march-to-the-sea-wasting-natural-resources/>
The canny reader will note that the depicted troops are not those of Henry V ravaging the French countryside. This is the Civil War and General Sherman's March to the Sea which is exactly the sort of warfare described by a chevauchée.
from above source
>
> This campaign is often regarded as a revolutionary war tactic because
> Sherman operated deep in southern territory without any direct supply
> lines. His methods of procuring the resources his troops needed and
> destroying what they didn’t in an attempt to weaken the Confederacy
> was an appalling waste of many resources gleaned from the environment
> and had catastrophic affects on the agricultural lands of the
> south...Later in his address, Jones explains how Sherman’s march waged
> war against women and children by pushing them to starvation and
> burning down their homes and property. He explains the ghastly state
> of the area after Sherman’s troops ravaged the land, “Such was the
> wholesale destruction of animal life that the region stank with
> putrefying carcasses. Earth and air were filled with innumerable
> turkey buzzards battening upon their thickly strewn death feasts”.
>
>
> In early 1865, Mary B. Chestnut describes the effects of the rampage,
> “There will be no aftermath. They say no living thing is found in
> Sherman’s track, only chimneys, like telegraph poles, to carry the
> news of Sherman’s army backward.
>
>
>
So to your knights: instead of engaging warriors they lay waste to the land. This is a crusade, not a war of conquest. Once the countryside has been crushed, the knights can go home and come back in the spring. A hungry winter will make the elves more tractable.
[Answer]
After reading the comment:
**Static siege.**
Basically, your model should be the [Battle of Alesia (52 BC)](https://en.wikipedia.org/wiki/Battle_of_Alesia) or [the Siege of Acre (1189–1191)](https://en.wikipedia.org/wiki/Siege_of_Acre_(1189%E2%80%931191)#The_double_siege). Your invaders build a double palisade with towers to warn against skirmishers.
The problem with mounted archers as the elves have is that they can't take fortresses and they can be killed by shooting from secure positions.
Once built the siege's wall, the invaders start mining the walls or attacking them with rams well protected against projectiles. Because they outnumber the defenders they can make these attacks in two or more places at the same time or make relays to fight at night and meal times.
If your elven cities are far away one from the other, they need the resources from the neighboring fields and forests. Punishing expeditions from your invaders to grab everything edible and burn the rest could work: your invading force has a good heavy cavalry, they can protect their own skirmishers.
Basically, when the crusader armies fought in the Holy Land against the Turkish cavalry archers, they placed their cavalry in the middle, protected by troops with shields. When they were attacked, the crusader crossbowmen picked their targets and from time to time the ranks opened for a charge of their own heavy cavalry.
As powerful as horse archers are with their hit-and-retreat tactics, they usually only bring a limited supply of arrows, so waiting for them to run out of ammo and not falling for the trap of following them into an ambush is a good strategy.
However, I guess your supply lines are very long and your elven skirmishers will attack them. Protecting those lines was the main problem in a lot of Medieval wars and there is no good tactic other than "committing a lot of troops to their defense".
[Answer]
(Hello, allow me to sing to you the song of my people!)
>
> I know that guerilla campaigns are frequently unsuccessful, but most of the information I can find about combating such tactics are for modern armies.
>
>
>
Have you ever heard of a man, a giant of his time physically, being over six feet tall; as well as politically, as one of the fathers of a not-inconsequential nation called the United States of America; and also militarily, as *the general of a successful guerrilla campaign against a much larger, better trained, and better equipped British Empire*?
His name was George Washington. (<https://www.youtube.com/watch?v=l7iVsdRbhnc> Link contains language that some may find offensive.)
Seriously though - the only advantages the Continental Army had at the beginning of the war were 1. it was fought on their turf, and 2. they had better marksmen. As a result, a guerrilla campaign was the only option that played to those advantages while minimizing the number of men killed by the British in open fields.
Guérilla techniques ***work*** against conventional armies. That's why the only information you're finding about successfully combatting them is modern: as a species, humans did not begin systematically developing asymmetrical techniques to defeat guerrillas until the late 1800's in Cuba and South Africa, and did not begin codifying those techniques until after WWII.
**I'd suggest researching those modern, asymmetrical techniques, and seeing if the humans in your setting can begin to develop them with the technology and military they have available to them.** Otherwise, it's more likely that your Elves would win.
[Answer]
**Diseases**
Do what every good human invader has done to the natives and that's give them your own lovely Diseases "small pox just a dirty human thing, last thing an elf says before his whole settlement gets wiped out" hell the humans may not do any fighting at all just give your sick to the elf's (they like slave right); Don’t worry even if they kill them the sickness is already at work reeking havoc to their bodies and minds. If your men can’t get close? Just catapults the pox covered clothes over there walls and just wait till they open the doors begging for death. the elf's have gone bush you say, well just send out a vulnerable caravan filled to the brim with said clothes and some nice blankets "I hear it will be getting cold soon" then let them run off to their Little rats nest and let the pox do the rest, most will be dead before winter comes knocking.
**Infiltration, Intel, And Assassination**
>
> (If you know the enemy and know yourself, you need not fear the result
> of a hundred battles Quote by Sun Tzu)
>
>
>
Use your elven allies to infiltrate the enemy camps, doesn't matter if there is only a few of them use them to their fullest. Intel is key in any war this one included, find out where the enemy camps are, their numbers and fighting strength a wise general is a great general. When you get all the info you can. You start attacking them in their homes, poison there water burn their supply's kill their commanders. Killing the commanders and strategists is very important doesn't matter how many they are or how elite they are cut off the head and watch it wriggle. Make sure the elves don't do the same to you as well the reason I said the above is because the tactics are effective, expect them to do the same. Make plans around their plans and you could turn this war around
[Answer]
The previous mentions of chevauchée covers the physical angle quite well, but there is another way to interpret the directive to inflict carnage upon the offending elves: to strike not just at the material body, but also at the racial psyche
# Full Mithril Jacket
To weaken their spirit, the humans can target their holy sites and other places of note to the elves' culture. Intelligence from the friendly elves' will be invaluable to determine where exactly to strike. Their temples are to be sacked and razed, their wise elders to be killed as priority targets and any means of passing down their culture and history to be destroyed.
The human army will have to lay siege to the elf city eventually. When they do so, they can do it not just with their troops and field fortifications. They can borrow from Vlad Tepes' playbook and surround them with a ring of captive elves impaled in plain sight and left for the carrion eaters. Troops would then accompany the stakes with shouts of "Come and get them, cravens!". The goal with this is to anger the Elf Cong enough that they will sally out in force; when they do, the human army can finally engage and defeat them decisively.
# Castle Elfeinstein
Elf captives don't all have to be killed either. Instead of execution, they can be sent to Auschwitz-equivalent camps to be experimented on in all sorts of sick and twisted ways in the name of 'science'. This may be too dark for your story though, so you could omit this. Another way of dealing with that issue is to make Elfschwitz fake; no more than bait for the Elf Cong. Leaked to hostile elf leadership, word that their captives are being tortured in unspeakable ways in this particular fortified camp(s) could draw the Elf Cong into a decisive engagement if impaling captives alone doesn't cut it.
Rape can be employed against the elf women(especially those they hold in high esteem). Soiling the purity of the elf race cuts deep in ways swords alone never will. Once again, could be too dark though.
[Answer]
From a strategic point of view:
1. Destroy enemy fleet
2. Capture enemy port, close to your supply lines (good elves)
3. Disembark and create a military outpost
4. Start to chop / burn forest around your spearhead
5. Contact and bribe local tribes / factions antagonistic to ruling faction (hard to imagine that 100% of population are happy with the current rulers)
6. Use local info to map towns / garrisons / main resources
7. Send military raids to crucial economics assets (can be mines / food fields / ports) or to capture key people.
8. Force the bad elves to send his armies to YOU. --> field battle --> profit
] |
[Question]
[
This is as much a question as it is a thought that I've had. You see, folding mountains (as in made by tectonic plates movement) are very poor in heavy minerals like metals, and they seem to be the ones we most often see dwarves.
It is probably because of the Hephaestus myth and the "volcano as a forge" kind of thought that this aesthetic set off, but I seem to remember many stories where it was not a volcano but a regular mountain.
To me it would seem fun to explore other possibilities, like a mine in the middle of the desert and all that that would mean in terms of food/water supply and caravans routes. Some good stuff that you don't see a lot in the usual medieval European fantasy. Open-pit mining is also a thing.
So, just a few thoughts about Dwarves and Mines. Please correct any mistakes.
[Answer]
[Hephaistos](https://en.wikipedia.org/wiki/Hephaestus) (or, as the Romans would have written his name, Hephaestus) of the Greeks and [Vulcan](https://en.wikipedia.org/wiki/Hephaestus) of the Romans were metal-working gods. Hephaestus was said to be rather ugly, and lame in a leg; but they were *not* dwarfs by any measure. (Hephaestus managed to arrange it so that, although ugly and lame, he ended up married to Aphrodite, lucky god as he was.)
[Hephaestus giving the arms of Achilles to Thetis](https://en.wikipedia.org/wiki/Thetis_Receiving_the_Weapons_of_Achilles_from_Hephaestus) by [Anthony van Dyck](https://en.wikipedia.org/wiki/Anthony_van_Dyck) (17th century) on [Wikipedia](https://en.wikipedia.org/wiki/File:Anthonis_van_Dyck_066.jpg).
The dwarfs of fantasy novels are modeled after the dwarfs of western European folklore, mostly of Germanic origin, and *those* dwarfs are miners and hoarders of treasure; for example, the dwarf [Alberich](https://en.wikipedia.org/wiki/Alberich) from whom Siegfried stole the [Nibelung](https://en.wikipedia.org/wiki/Nibelung) treasure. (In Wagner's opera cycle, the Nibelungs themselves are dwarfs.)
Now they being miners they naturally lived in the mountains, because in western and central Europe most mines are in mountainous areas. See, folding mountains are *usually* less rich in minerals than volcanic mountains, but *usually* does not mean *always* and anyway volcanic mountains are usually dotted here and there in the folded ranges; and the mountains are almost always richer in minerals than the plains.
For example, in central Europe there are the [Ore Mountains](https://en.wikipedia.org/wiki/Ore_Mountains), which have the richest silver deposits in Europe, and which have been mined since the middle of the 3rd millennium before the common era; there, in [Joachimsthal](https://en.wikipedia.org/wiki/J%C3%A1chymov), beginning in the 16th century, were minted the well-known silver coins named *[joachimsthalers](https://en.wikipedia.org/wiki/Thaler)*, a name first shortened to *thaler* and later mangled into *dollar*; there, in the 16th century, [Georgius Agricola](https://en.wikipedia.org/wiki/Georgius_Agricola) wrote his famous book *[De re metallica](https://en.wikipedia.org/wiki/De_re_metallica)*, the first serious book about mining and minerals written after the fall of the classical civilization. A very good place for a tribe of dwarfs mining precious metals, isn't it?
[Answer]
Mountains are much more defensible than plains or hills. It only makes sense that dwarves would build their fortified cities in the mountains and then if there is a lack of minerals at the city site (and really, who wants to live in a mining site) go down to the foothills to mine.
Also it's probably easier to carve your huge halls and gigantic statues out of a big mountain than to dig through the silt on the plains down to the bedrock.
[Answer]
In our own world, native populations that live in high altitudes tend to be of short stature. This is an adaptation since a shorter height leads to reduced surface area for heat loss. Of course, this only answers the inverse of this question, which would be "Why do people who are native to mountains tend to be dwarves slightly short?". Still, if we believe natural selection to be a thing in fantasy worlds, then this would at least somewhat explain why mountain races tend to be Dwarves.
[Answer]
The reputation of dwarves for metal-working is vastly overrated. If not unjustifiable, because it's what's traded the farthest. If you actually go near dwarven regions, you find they are also noted for their wood carving, and their cheeses. There are many accounts of how they were forced into the mountains by giants, for their defensive superiority, but they adapted so well they do not want to leave.
They practice transhumance, although they bring the animals into the caves and feed them hay during the winter. They raise crops. They live outside in wooden houses. They are also noted for their mercenary forces, which contributes to their metal working reputation, because they make their own and make them very well.
[Answer]
**Dwarves are well-adapted for mining** Ores occur in seams, many of which are a thinnish layer between layers of non-productive rock. It is not a coincidence that pit-ponies were a small tough breed and short in stature. When mining you don't want to burrow through solid rock if you can help it and so the height is determined for you by the geology. Over generations, shorter people will be selected for.
You can see from the following picture that shorter people would be much more at home in these conditions.
[](https://i.stack.imgur.com/PUTbt.jpg)
---
**Why in mountains?** Because access to seams is much easier on a fault line where an upraising or erosion has exposed the ores at the surface. Here's an example
[](https://i.stack.imgur.com/Ok2Ys.jpg)
---
**Dwarves and palatial caverns?**
Caverns occur naturally. Now and again the dwarven burrowings will uncover such a place. When their underground kingdom is established they can start to carve and build in a more artistic fashion.
[Answer]
Because dwarves love to mine.
We are talking about a low technology situation--pumping water out of a mine will be exceedingly hard, especially since you can't suck water up very far--you have to bring your pump power down the mineshaft.
Thus dwarves will make mines that self-drain--dig sideways, not down.
[Answer]
Well maybe your Dwarves sunburn *very* easily. In which case they would want to stick to dark areas. Underground and when they had to go above, then they could take advantage of the massive shadows of mountains to reduce light levels hitting them(or you know, just become nocturnal) Bring in the Vampire Dwarves!
[Answer]
>
> You see, folding mountains (as in made by tectonic plates movement) are very poor in heavy minerals like metals, and they seem to be the ones we most often see dwarves.
>
>
>
You got it the other way around. The world was initially flat. The ancestors of the modern *homo Hortorum decus* (i.e.: dwarf) dug most of the surface. The dwarves you see are digging up the last leftovers of an ancient layer of rock and dirt. When they are done, the dwarves of the future will dig up the next layer.
[And if you are curious about where all that rock and dirt went...](https://youtu.be/zggbAZAFpcw?t=17)
] |
[Question]
[
I am looking for a number of slow accumulative poisons say over a 6 month period that is detectable in autopsy and would slowly but surely kill the patient. The poison would be hopefully something a doctor or nurse could obtain as the poisoner will be a medic. Thanks!
[Answer]
Low levels of cyanide. It's not lethal in small enough doses, but will build up if the dose is large enough.
Can easily be obtained from natural sources such as [cassava root](https://en.wikipedia.org/wiki/Cassava#Food_use.2C_processing_and_toxicity) (the root that tapioca is made out of). So basically improperly processed cassava root will be your friend (you may need to sweeten it because cyanide tastes bitter).
Is naturally purged from the body with one of the vitamin B12 compounds [vitamin B12 compounds](https://en.wikipedia.org/wiki/Cyanide#Antidote). Chronic lack of vitamin B12 leads to [anemia, neural damage](https://en.wikipedia.org/wiki/Vitamin_B12_deficiency#Signs_and_symptoms) and [ultimately death](https://www.ncbi.nlm.nih.gov/pubmed/20158555).
[Answer]
[Arsenic](https://en.wikipedia.org/wiki/Arsenic) and [lead](https://en.wikipedia.org/wiki/Lead) fits your specs: they cumulate in the body and slowly kill it. See [Arsenic poisoning](https://en.wikipedia.org/wiki/Arsenic_poisoning) or [Lead poisoning](https://en.wikipedia.org/wiki/Lead_poisoning) for more info.
[Answer]
If your patient could spend a lot of time around artwork, consider some [classic oil paints](http://www.albrechtdurerblog.com/oil-paints-kill-albrecht-margret-durer-poison-customers-paintings-part/). Your antagonist, if suspected at all, could use the excuse, "I didn't know those were deadly!"
I remember seeing an old movie where someone was killed over time by, I think it was called, *Paris red* paint in his home. But having viewed the link above, I wonder if it was *Paris green*.
[Answer]
Chronic lack of B12? I suspect you are thinking about niacin, lack of which is pellagra, takes forever, and is easily reversible by eating meat.
In this hypothetical I would go with polonium or ethylene glycol because you're looking for something that CAN be detected. Warfarin and nicotine also come to mind. Have you tried watching TV?
] |
[Question]
[
Say there was a totalitarian regime that controlled 1 billion people. The GDP is ~$50,000 per capita.
This regime has nigh on total control over them, however, rebels are still considered a serious threat to their power.
If you were the newly appointed head of the Ministry of Safety and your job was to manage the myriad of intelligence sources the country had, (Cameras, texts, mail, etc.) what methods would generate the best results?
The Party will be grading you on these metrics:
+Quantity: The total number/% of people(surveiled?). This should be as close to 100% as possible.
+Quality: How *often* any particular person that is *not* under direct suspicion is watched (What sort of *subversion* could they be up to in the meantime?!)
+Cost: The lower the cost the better, although not at the expense of the other metrics($ cost per person).
Your class 8 dwelling awaits, comrade Minister.
[Answer]
*People don't seem to have answered the question in the way I understand it...*
# Machine learning.
As wrong-doings are committed, patterns arise - in other words, series of events correlate to end-point crimes. Computers, running ML algorithms, monitor all; camera, mobile and internet feeds available to you. The Ministry of Safety gets notified when a potential crime is detected. Records get created this way, on the fly, those who have offended multiple times get monitored more vigorously.
How does this save money? Well, let me highlight some key points:
* allows for multi-tasking
* avoids hiring tons of staff
* memory components get cheaper every year
* crimes get organised via severity, prioritising your time
If you're sceptical about the data processing costs, don't fear. Our state of the art compression techniques are utilised through cryptography. Unlawful patterns are matched in the computers RAM, in which pulls learned formulas from a secured data centre.
I'll quote you on $200,000 a year. I know, a slight increase in comparison with what you expected, but you'll need to configure your long game. Let's not forget about all of your other expenses.
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Smartphones offer a 100% picture perfect clear image of what one's daily movements are every day. Fingerprint scanners also cough-up everyone's fingerprints into a central database. Siri is capable of understanding every word you say whether you are talking on the phone, or not. Facebook users reveal their personal network. Linkedin reveals your professional network. Facebook also uses selfies to build facial recognition profiles. Look anywhere in the USA, and you see security cameras. Via search, Google knows your personality. All of this is already stored in a digital, searchable, format. Currently, **all** of that data is being collected. Just link all that data together with the unique id being a facial profile and a fingerprint.
People *want* to reveal all that data. People are social animals. Disk storage space basically costs nothing.
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/what methods would generate the best results?/
Absolute best results are produced by faking them, and nowhere is this more true than in a totalitarian regime. In a command structure like this, as new Minister I would deduce what intelligence results would best advance my own political position and those of my allies / patrons while hurting my political opponents. Real world data collection would then be done in a way to buttress the results I need, as well as bear some scrutiny by those who might not like my conclusions.
For example: my superior Comrade D is not interested in knowing that his own home town has anything untoward going on, but is interested in his rival Comrade F being portrayed as possibly dangerous with dissident inclinations. Data obtained would be done in such a way as to support these conclusions. If F complains about lackluster intelligence collection and bias, suggestions by F on how to improve data collection would be enthusiastically received and documented then poorly implemented. Alternatively F might include with his suggestions other incentives, in which case his suggestions might turn out to be very useful, with due credit accruing to him. Fakery is also inexpensive and I will always hit my budget predictions.
I am delighted by my new class 8 dwelling although it does not have anything like the beautiful pool at your Class 5 dwelling, comrade D. My children love it! You are so kind to invite us to your home.
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It's not a matter of WHAT info you collect, but HOW do you make intelligence out of that info.
It's not the dots to bring value, but the line you draw between them.
So I would say invest on an intelligent system to crunch all the data you gather.
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Let's take a look.
* Cameras. Great for general surveillance of places, but sadly most of them are video only. So you'd have a lot pictures of people, but no audio.
* Smartphones. Great location, audio and video surveillance. But, as today, GPS can be spoofed, smartphones can be shut down, forgotten or exchanged with other peoples or thrown away.
* PCs / Notebooks. Great for general sniffing around, because there are passwords, browser histories and stuff. But sniffing only works on the most popular Operating Systems. Try to sneak up on a custom configured Adamantix.
* Spies. Trusted servants of the state, can gather information from the human source and influence a rebel groups actions. But once their cover is blown, their cover is blown and getting information from the spy to the guide is also very tricky and risky.
So, there is not *the one* technique but a lot of them which have to be combined to get the best information out of them. Maybe you could ask for a workshop / training at [Palantir](https://www.palantir.com/) for more information on the subject.
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In a totalitarian state you can also control every company and therefore use e.g. the bank information of your people to know what they are up to.
You can combine this with an early education to share as much information as possible. Make it socially unacceptabel to not share your private information and people will tell you what they are doing.
If they are not sharing their information voluntarily you use companies, smartphones, laptops, cameras, etc... But most likely other people will report them to you and tell you about them. Because that is how you educated them.
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In the 13th century C.E. especially during the mating season, dragons can grow to over 15 meters in length. Twice a year they will flock together and fly across the Pacific ocean to find mates. The problem is during this time many houses will be smashed to pieces by the dragons' dropping as they fly over. Each dragon is capable of producing up to 50kg of solid waste matter. These dragon are docile by nature by will become aggressive when provoked, they usually hunts in pack.
How do the people in the medieval age built their houses that can withstand punishment from the innocent dragon? Interestingly the migratory route usually covers fertile land near to fresh water source.
[Answer]
Just build solid wood houses.
There's a Mythbusters episode, where they drop a piano on an old country house, and it turns out that normal roof beams (ca 30x30cm) are pretty stable. They had to fill the complete piano with bags of sand to make it crush through the roof and by that time, the piano weighted much more than your dragon poo.
During mating season there may be minor repairs and now and then a loud bang. But that wouldn't be a problem because the benefits are much bigger:
Dragon guano! All the farmers will happily buy the stuff from your village, because dragon guano is one hell of a fertilizer for reasons.
There's a by far worse scenario you should worry about:
Dragon diarrhoea.
I leave the rest to your imagination.
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## Mythbusters Episode: "Piano Pile-Up"
I couldn't help but want to look up the details of the Mythbusters episode Alexander mentions in his answer. [Here is the video](https://m.youtube.com/watch?v=0zTtuuNK2N4&t=7m25s), and [here is the summary](https://en.wikipedia.org/wiki/MythBusters_(2014_season)#Piano_Pile-Up):
(Edit note: The Mythbuster video has been removed from YouTube, and I haven't found a replacement. However, there *is* [this video which shows the same concepts](https://www.youtube.com/watch?v=U21raUMtQx8) - Even if it is just a bunch of people dropping a piano on a house for fun.)
[](https://i.stack.imgur.com/xYlS0.jpg)
>
> **MYTH:**
> A piano dropped onto a house built in the 1800's will smash cleanly through both the roof and the floor.
>
>
> **STATUS:**
> BUSTED
>
>
> The Build Team found a one-story house slated for demolition, marked several target points on the roof between joists, and used a construction crane to hoist and drop various pianos from a height of 50 feet (15 m) above the roof:
>
>
> * An upright piano weighing **700 pounds (320 kg)** damaged the roof but bounced off without penetrating.
> * A baby grand piano weighing **1,400 pounds (640 kg)** pierced its legs through the roof but was unable to fully break through.
> * Calling the myth busted, the team loaded another upright piano with enough sand to reach a total weight of **2,600 pounds (1,200 kg)**, much more than a full-size grand piano, then dropped it from 75 feet (23 m) above the roof. This time, the piano did smash a hole in the roof and landed on the floor.
>
>
>
So, Alexander seems to be correct--your average house will not be damaged much by 50kg of poop. Houses generally speaking seem to be able to stand up to 24 loads of guano simultaineously on the roof before breaking.
## Wind Break
To protect the houses from the intense winds generated from flapping of wings, the houses could have rock wall wind baffles around them:
[](https://i.stack.imgur.com/c51oW.jpg)
This would send the intense winds up and over the roofs.
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**Against droppings** build houses with steeper angled roofs, like you see in alpine regions. This increases the area hit from above, distributing the kinetic force more evenly, while also flattening the impact angle, thus making it more likely for the solid parts to ricochet. Also non-solid components will slide off faster and more easily.
**Against wind** reduce the wall heights (even better: have no walls at all) and get rid or corners that will create low-pressure air pockets.
Your final design would probably a cone-shaped structure where as much room as possible has been moved below ground level.
[](https://i.stack.imgur.com/wHCnq.png).
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just build them underground or use tunnel/[Arc](https://en.wikipedia.org/wiki/Arch)-shaped structures with a similar physical principle to direct the force of the falling dragon around your house. How to build a strong arc is common knowledge during medieval times
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Depending on how far above the ground the dragon was when they poo, it might or might not destroy the roof.
The piano in mythbuster gave 270,480 kg m2/s2 (from 1,200 kg x 23 m x 9.8 m2/s2) worth of impact to bust the roof.
To achieve the same impact, dragon poop needs to be dropped from at least 552 m above the roof (270,480 kg m2/s2 divided by 490 kg m/s2).
Thus to prevent houses from getting destroyed the dragons needs to fly low. Or you can have the roofs more pointy to reduce the impact. But pointy house would be weaker to the wind since they need to be tall and tall things don't go so well against the wind.
My suggestion is that your people needs to develop an architecture that allows the wind to pass throught the house while at the dame time have pointy roofs.
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Let economics take care of it. Slate (or otherwise fireproof) roofing materials will command a premium over wooden shingles or thatch roofing in dragon-poop prone areas.
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In [this answer](https://worldbuilding.stackexchange.com/questions/20665/dragons-that-eat-gems-digestion/20723#20723), dragons droppings are used as building material for its mound. Except when out of reach of land, dragons don’t throw away waste.
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In addition to other considerations, the dangers posed by POOP FROM THE SKY are not very great.
According to [these maps](https://armedea.files.wordpress.com/2014/10/mosaic_density_map_homogen_light.jpg) population density in the relatively densely populated countries (Britain, France, Italy) ca 1300 AD ran about 40 - 50 per km2. Assuming a nominal household size of 4 (since living alone on a medieval farm is almost impossible without division of labor), that is about 10 houses per square kilometer. Now assume a cottage size of 10 m x 10 m, and the ratio of roof area to land area becomes 1:10,000. If, in the course of a year, an average square kilometer receives 100 impacts, the probability of a cottage getting hit is only 1 - (0.9999)100, or 1%
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The same way they build roofs to combat heavy snow fall. Very steep angle roofs with a solid wooden roof.
However, there is another option. And that is to hire a dragon slayer and remove the breast.
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Am writing a story that takes place in a setting set in space where, in terms of weapons, the people in it have pretty much the same kinds of slug thrower weapons as the present day.
I want to add a character in this setting who almost exclusively uses a sword to fight. Is this plausible? And, what reasons, if any, would this character have to use a sword instead of a gun, and what kind of strategies would one use if they were using a sword against guns. (Is skilled at using a sword)
[Answer]
I think this may be likened to the Jedi using light sabers instead of blasters.
1. I say it *is* **plausible** because the writer demands it and there are strange people doing strange things everywhere.
2. **Reasons:** These would depend on the environment. You state that the story happens in space. May I assume on a ship? This would provide a good reason or two as the constrained passageways will make a sword nearly as effective as a gun. The sword has the added benefit of being silent (for stealth reasons) and is a precision instrument that may allow you character a great deal of control over what damage (if any) he does with his weapon. You character could also fear using the gun on the ship as it might cause undesirable damage. (Hit a high pressure pipe, or whatever. You might also make ammo a hard to come by commodity (expensive and depleting, due to the long time spans between getting to a factory)
3. **Strategies:** Your characters main strategy should be something along the lines of: sneak up on them, then slice through the bunch like butter before they've even unholstered their weapons. Repeat on the next bunch. In close combat, one may assume that a skilled individual with a sword is more effective and efficient than one with a gun. This advantage disappears the moment enemies are out of reach, however...
Is this suitable to your purposes?
[Answer]
This is rather implausible for a number of reasons, especially if it is already established that slug throwers similar to current weapons (pistols, rifles and shotguns, presumably) are already present and accepted.
This automatically rules out the "guns are too dangerous in space" argument, we already know there are firearms, which suggests that space structures are solid enough to withstand at least one impact with a bullet. Even Bigelow type inflated habitats are relatively immune to gunfire, being built out of multiple layers of high strength fibres like Kevlar, and a Spacecoach type spacecraft is a Bigelow construction on steroids, with hundreds or thousands of tons of water in the interspace between layers of fabric (think of nested balloons)
Swords are also difficult to use in confined spaces (consider a castle in the middle ages had tightly corkscrewed stairs in a clockwise direction to make it difficult for a right handed swordsman to advance up the stairs), and most spacecraft designs are fairly confined. If anything, you would either advance with a pistol or sawed off shotgun, or carry a knife rather than a sword.
If there is an issue with gravity or Coriolis force, computerized gunsights can adjust for ballistic drop and "aim off" to compensate, while a swordsman has no such aids. In zero-g, the situation becomes even worse, a swordsman cannot function unless they are braced against something.
If anything, the two best weapons in a space setting would probably be a silenced weapon (purpose built silenced weapons like the Welrod pistol (<http://www.militaryfactory.com/smallarms/detail.asp?smallarms_id=423>) or the De Lisle Carbine (<http://www.militaryfactory.com/smallarms/detail.asp?smallarms_id=686>), or a grenade launcher with a revolver cylinder allowing you to quickly access different sorts of rounds for different occasions (flash bangs, chemical irritants, high explosive concussion or conventional HE/shrapnel rounds) like the MILCOR M-32 grenade launcher (<http://www.milkorusa.com>)
[Answer]
The 'easiest' answer is to invoke culture. Religions, traditions and historical affectations could all drive an individual to use what might be considered as a sub-standard weapon for the setting. Perhaps the character belongs to an order that forbids kinetic weapons, or that honours an older form of martial combat... with culture, the possibilities are almost endless.
As to practicality, that:s a different question. Some works manage to have good reasons - Dune, for example - but in most places your character is just going to get extremely well ventilated.
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Perhaps for stealth reasons. If you're character was some kind of assassin then maybe he would prefer to slit his enemies throat with his short sword then to engage him in a gun fight.
Perhaps for legal reasons. You said you were setting has guns but dose everyone have guns or just a few? Perhaps the regulations on buy selling and ownership of firearms are so restricting so that people just prefer to use sword that aren'the regulated?
Personal reasons. A Sword might be of cultural or religious importance to him.
"Magic Sword". your sword could actually be some form of advanced technology shaped in the form of a sword. Much like how wonder woman has a mother box in the shape of a sword. ( watch Justice League Gods and monsters to see what I'm talking about)
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You ask if it's plausible and I say look at the real world and you will find the answer is no, it is not plausible. Ever hear the phrase, "Don't bring a knife to a gun fight?" If swords were still a viable weapon, don't you think the military would still be using them? Guns require less training, are smaller, lighter in weight, have *far* more range, can be used in tight spaces, guns don't get stuck in objects, guns can be concealed, etc. Guns are just better.
[Answer]
Beyond sentimental and cultural reasons, of which you can build many and include, here are some practical reasons in a high-science setting.
**Peace shields**
In the TARDIS on Doctor Who (talking old Who here, think it lost this in New Who), he was able to turn on a peace shield that prevented firearms and laser weapons from working. This did not apply to more primitive weapons that didn't use combustion or high tech stuff. So anyone with a bow and arrow, knife, or sword was still deadly.
**Low Tech Zones**
Just like peace shields, but this might be naturally occurring, and it would not just apply to weaponry. There may be areas where all tech doesn't work properly. Once you've crossed over into one of these areas, all your tech and your guns just won't go. (I haven't given you a reason why, because there's whole range of imagination you can use for this--to keep certain people corralled and limited if it's not naturally occurring, to disruptive EM waves that render laser weapons inert.)
**Tech and Primitive Hybrid**
Your primitive weapon may have a hidden talent. It looks like a sword and can be used in places where guns aren't allowed (or there is something like a peace shield), but it can also fire pulses. Maybe it uses the action of the sword as stored energy. The pulses can knock the enemy down, actually harm them or...and this is sneaky, actually disable anything high tech. Also, the sword can have some sort of shield against ranged weapons over a certain velocity. You could even have the weapon be strengthened by the kinetic energy, using some crazy somewhat hand-waving science.
**Tracking**
Guns are used, however, there's a sophisticated tracking system in place. All weapons have a specific signature and any weapon fired brings the law rather instantaneously or barriers come down, trapping/containing the person until they can be arrested--and/or some kind of gas is used to knock out everyone in the area. (Maybe they have teleporters for law enforcement). If someone fires a weapon, they are going to make tracks just after. They might have a gun, but they only use it as a last resort because they know they will be caught immediately. Weapons such as swords are not tracked this way, so most criminals end up using bows, arrows and knives.
**Swords vs. Guns**
A gun is superior to a sword, in that someone with no training and a gun can kill a lot of people. Swords take skill. That you are putting a sword against guns makes the odds against the protagonist more stacked, so he'd going to have to fight smart and stealthy. People with guns don't expect someone to come up to them and disarm them. Your guy will get shot. I'd say armor or some kind of shielding would be a good idea.
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I'm looking to use time travel as a big element in my world. I want there to be a somewhat reasonable explanation for it though, so it doesn't turn into some magical wooble-booglly tech stuff. (credibility is an amazing way to engage a reader)
I've been reading A Brief History of Time, by Stephen Hawking. I read that like Gravity, there are other "Major" forces in the universe, such as Electro-magnetism. I also read somewhere that gravity can bend time (time would flow slower near heavy objects).
While I have no doubt these effects are negligible compared to a human life span, I was wondering if forces other than Gravity would also be able to bend time. And if so, would that mean time is basically another spatial dimension (like X, Y, Z) which we just can't perceive as such?
[Answer]
The most rigorous depiction of a time travel device that I am aware of is the "Tipler Cylinder" (sometimes called the "T" machine).
The principle is rather simple, twisting or warping space-time in such a fashion that a light cone begins to point to "otherwhen", allowing access to different times (or places). While simple in concept, the mechanism to do so would require an infinitely long cylinder of neutronium spun to almost the speed of light in order to deliver the required torque to space-time. My local contractor hung up when I asked for a quote....
[](https://i.stack.imgur.com/dekxI.jpg)
The concept of a light cone explained. As you travel forward in time, you can see or remember events inside the cone (bounded by the speed of light. Anything outside the cone is invisible and inaccessible by definition since any signal would have to move faster than the speed of light to get to you).
[](https://i.stack.imgur.com/7gaaF.jpg)
This diagram provides a relatively clear explanation of how the Tipler Cylinder is supposed to work. The technical term for what is happening is "frame dragging", and in general relativity, even the modest amount of bending of space-time by an object like the Earth should demonstrate this effect, although it would be so small that measurements would probably be at the limit of accuracy for most modern equipment.
It is possible that finite objects like rapidly rotating neutron stars or black holes, or finite T Machines made by some super science could induce enough frame dragging in order to be useful as time machines, although I have never seen any proof of this.
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Yes time is our fourth dimension. We are living in a four dimensional spacetime with three space dimensions and one time dimension. There are two ways to alter time: Time dilation caused by motion with very high speed and by gravity.
One can say: "Space tells matter how to move and matter tells space how to curve".
I don't know if time can be altered by one of the other three forces.
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I'll preface with "I'm not a physicist", and fiddling with time and space is something that gives work to actual physicists who are smarter than all of us collectively.
Classically, space and time form 4 dimensions. A simple manifestation of time is movement, as movement can be expressed as variation of space over time. The way I understand it, gravity deforms space *and* time, but it doesn't alter the direction of time, which would make going back impossible this way.
If you are interested in travelling to the future, there's a loophole of sorts. You could use time dilation when travelling close to speed of light to effectively travel into the future (in actuality, time would simply move much slower for you than it would on Earth, hence a second for you might translate in centuries in the outside world). It's a one way trip.
Our current understanding is simply that time doesn't work that way. You can't skip forward or backward, you're stuck with going with the flow, and although said flow may be doing funky stuff at high speed or under high gravity it still goes in the one direction. Then again, there are a lot of things we think we understand about the universe, then we find out we didn't.
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It's all about having a good grasp of your **Time and Relative Dimension in Space** (if only there were a good acronym for that, like TARDIS or something).
Apparent time travel to the future of a physical location in space (faster than 1s/s we all manage by just sitting around) seems permitted under current physics at great energy expenditure costs (all you need to do is shift your $\vec{u}$ vector to be mostly in the physical dimensions rather than the time dimension relative to your starting inertial frame and back again while not dying horribly in the process), so that should be fine and easy, as long as you have **galactic levels of energy** lying about ready to be used, which you do, I'm sure.
Time travel to the past, also known as FTL signalling, involves a complete breakdown of causality and appears **strictly, inexorably, ineluctably, unforgivingly, inescapably forbidden** by our understanding of physics. Which must mean, of course, that our understanding of physics in incomplete, because, as we all know, past-oriented time travel is **too cool** not to exist. Paradoxes be damned, who does not want to try and seduce their own 19-year old grandma, after all? Don't answer that.
So let's assume an **abundance of multiverses with thin walls**. This means that when you go "back" (using the old **negative mass-lined wormhole** generator that looks deceptively like a blue police box on the street corner) you're really invading an alternate universe. No wonder the young version of grandma thought you're out of this world. You really, really are.
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Time travel to the future is no problem, all you have to do is go very very fast (like close to the speed of light) - this is in the theory of Special Relativity. Time slows down for you therefore you are moving into the future at a rate greater than 1 second per second relative to everyone else, and so effectively time travelling to the future.
Time Travel to the past, though? I'll leave that as an exercise for the reader...
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For accuracy, have a look into closed time-like curves. The answer to "accurate" time travel may simply be that "it is already happening that way and will have always already have happened that way and had always been about to already have happened that way"; there was no before and after, only a self-consistent wave-function.
But where's the fun in that? If you want fun time travel, I'm in agreement with Separatrix's comment: don't go into the details at all, just take it as given. How many old sci-fi movies/shows/stories look silly when they try to explain the details? You can avoid that by describing *what* it's doing, not *how* it's doing it; it never once bothered me that I didn't know how a tricorder worked when watching Star Trek.
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Ultimately the reader will have to accept time travel, because if you could give a perfectly reasonable explanation, we could already time travel in real life. Ideally those stories add a new key element to physics that was unknown to us (or it was just theoretical), and that does not affect anything else, thus not changing physics and the world more from how we know it, which makes it very easy to keep a consistent, logical narrative.
What I find more interesting is giving the invention of time travel out of the hands of human. Either Aliens somehow (who cares, it was the aliens) invented it, or humans from the far far future did (at least we invented it somehow far far away from our future).
You could maybe extend these to a point where no one reasonably understands why they work. The reason for them to invent time travel maybe was to populate the past, because their future present home planet is dying. Unfortunately in all that hassle advanced knowledge was lost and they only ended up with the working technology.
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One simple (to explain) method of time travel is to split off a copy of the universe, identical except that time moves more slowly there than in the original universe. So a year might pass here at our rate of time, while in the alternate universe, only a day has passed. Imagine if you had split off the alternate universe Jan 1, 2000. It would now be Jan 17, 2000 there. Want to travel into the past? Just point your alternate-universe portal device to the slow universe, and step into the year 2000!
This type of time travel eliminates all the usual time-travel paradoxes. Travel back in time and kill yourself? You won't disappear. Get back home, and you are still here.
Since we are talking fiction, you are not limited to the boring physics-centered time travel methods. You just need a way to step between universes, and a way to trigger a universe cleave. Both take very little energy.
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An alternative way of looking at time travel.
Temporal symmetry causes us to travel back and forth through time constantly. Unfortunately, your body and mind is also caught up in that shift like the rest of the universe, so you don't remember it and don't change anything.
To achieve 'time travel' then, we must find a way to isolate the matter and energy of a person from that normal flow. Most methods discussed use wormholes or massive rotating bodies to isolate an area of space in which that matter and energy exist.
If you are willing to allow a form of teleportation then the energy requirements for time travel reduce significantly since you would only need to isolate a narrow beam path for the energy that does not even need to support life during the passage.
Reassembally on the other end becomes the problem at this stage. Perhaps you are limited to traveling only to times which had a functional teleportation chamber. Or, perhaps you have devised a method of self reassembling energy into matter. In which case, awesome.
This then leaves us with the problem of targeting your destination. If you are relying on the natural ebb and flow of temporal symmetry, well, we've never had any tools that can measure this, we just know that mathematically it should happen. If you manage to build an energy isolation tunnel as I suggest, then you finally have the first steps for a tool to measure that flow. Which means that you, as the author, get to decide when, and when too, your characters can travel based on that ebb and flow, as well as how accurately they can measure and predict it.
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I'm trying to design a mammal that lives in trees. I'd like its hands to be good for climbing, but not good for using tools.
What aspects of the hand would make it good for climbing and not good for tool use?
[Answer]
Lots of creatures climb, few creatures create and regularly use tools. Fewer still if you want human level dexterity in the hands.
**Options**
* **Hooves**. Goats are amazing climbers on mountains...less so in trees but just an example.
* **Spider monkey hands**, they don't have thumbs, they use their digits to hook around tree limbs.
* **Cat paws** (as mentioned by Tim) I would look specifically at Jaguars. They spend a whole lot of time in trees.
* **Rodent paws** (as mentioned by Aify)
* **Bear paws**, sun and black bears are pretty darn good climbers
So the common themes here are.
1. No opposable thumbs. This makes tool use more difficult and would increase wear on a tool, a firm grip is key for not stripping a screwdriver head for example.
2. Claws. They are sharp. They break things.
[Answer]
The first thing that come to my mind is a Sloth. Just think of trying to use any tool with claws 4 inches long. Then think of trying to climb with grappling hooks!
Their specialised hands and feet have long, curved claws to allow them to hang upside down from branches without effort. They usually eat, sleep, and even give birth hanging from limbs. They sometimes remain hanging from branches after death even if shot from below by humans.
<https://en.wikipedia.org/wiki/Sloth>
[Answer]
All you have to do is look into nature.
Geckos use setae in order to stick to surfaces, and if your hands have setae it would allow the creature to climb smooth surfaces easily (perhaps really large trees with smooth bark?).
But climbing can't just be generalized to smooth surfaces, and you mention trees - so what other aspects can help improve this? Well, snakes can climb trees. Snakes get their friction from their scales, which could also damage tools, so this counts for double points!
But whenever I think of climbing trees, I think of squirrels. Have you ever noticed how damn fast they move up them? I'd use their paw design - 4 longish fingers with claws on the end, with no opposable thumbs. Turns out, opposable thumbs are pretty important for using tools.
The verdict? Use a combination of natures finest. Style your mammals hands after squirrel paws, but also give them some scales and perhaps setae on the finger tips.
[Answer]
Have it use the cat design rather than the monkey design for climbing.
In other words rather than grasping/manipulating hands it has more simple paws with claws that it uses to grab into the bark of trees rather than hands it uses to grasp branches.
[Answer]
# It's not the hand, but the brain
The ability to use tools effectively comes from the brain's ability to adopt this dead unfeeling extension as part of its body image.
A paw designed for swinging from branches or climbing or otherwise grasping in general might seem to make a perfectly good hand: if it can grasp a branch and hang on with enough force to support his own body weight, certainly then he can grasp the handle of an axe, right?
But, even with the *grasping* ability, he can't actually *use* an axe because his brain doesn't have the circuitry to make it function as an extension of his arm. It takes a great deal of practice to hit anything and the skill only works on that "trick" and doesn't generalize.
Note that I'm not referring to other aspects of intelligence. These creatures many have complex social interactions with politics and schemes, remember vast territories of resources and what signs indicate what to expect of the world around them. But using tools is a particular brain feature, and one we take for granted.
[Answer]
Bad for tools? **Just take away the thumbs**.
Good for climbing is very open-ended, as the other answers have showed with plenty examples. Here is a fun one:
**Hands with lots of tiny retractable claws all over the palms**
You put your hand against vertical rock, and any cracks will get filled with your little palm-claws, giving you heaps of purchase. These claws would give a world of pain when you slap someone, too!
A downside is a slimy surface would be impossible to climb, but you can use that as part of the ups/downs of the system.
[Answer]
Give it sloth hands.
[](https://i.stack.imgur.com/mfIhY.jpg)
Big curved claws, useful for climbing and hanging from trees but useless for tool use.
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[Xenomorphs](https://en.wikipedia.org/wiki/Alien_(creature_in_Alien_franchise)) are one of the most dangerous, deadly aliens in movie history. They breed in massive numbers, live in an ant-like society, and have blood that doubles as concentrated acid.
Most of those aren't a problem to figure out as we have many creatures on Earth with those. The biggest difficulty with designing this creature lies in its blood. As far as I know no creature, anywhere on earth, ever has had acid blood.
**What would the evolutionary history be for a creature with acidic blood?**
[A list of all of the *Anatomically Correct* questions](http://meta.worldbuilding.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798)
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The internal salt levels and acidity of the liquids in our bodies are largely set by our evolutionary history since pH changes how proteins fold.
So if a creature evolved in an extremely acidic environment then later had to adapt to being able to live outside that environment then its internal biochemistry could still end up locked to being very acidic.
The problem is that the Xenomorph blood in the films is very very very acidic. It eats through many layers of metal and even hardened glass. That's strong acid.
**But it's implied that Xenomorphs are not natural creatures but rather biological weapons of some kind.**
This opens another option: If you're using bioweapons you don't want your enemies to be able to take your weapons apart and analyze them easily. With engineered creatures even a spatter of blood could be used to recover details of how to achieve capabilities you've engineered in.
So how might you protect the details of your creatures biochemistry? well, you could engineer the creatures cells to include tiny hardened Teflon (one of the few substances which can survive it) vacuoles of, say fluoroantimonic acid (pH of −31.3 one of the few materials potent enough to match the capabilities of the alien's blood in the movies) engineered to burst once the cells are detached from the main body.
Detached or damaged tissue now dissolves into unusable gunk, possibly even taking the floor beneath with it.
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That the xenomorphs in the Alien/Predator/Prometheus movie series have been shown to be artificial bioweapons is a significant datum that means that their capabilities have not merely evolved, but have been intelligently designed, and may therefore have traits incapable of evolving naturally.
Another significant datum is that the movie series has shown them to have originated as a 'black oil' - likely to be some sort of nanotech in my opinion. That the xenomorphs anecdotally have "Acid for blood" is not *proof* that their blood is acidic: another plausible explanation is that their body fluids appear to dissolve solid substances because their body fluids contain nanites that carry metabolites while circulating within their bodies, but on being spilled, change from metabolite transporters to nano-disassemblers. That they don't keep disassembling stuff forever is simple conservation of energy: each nanite has a limited supply of energy, and disassembling stuff takes energy. Once the energy has been consumed, the disassemblers stop functioning.
Another significant datum is that the xenomorphs have been shown to be able to grow in environments rich in organic matter - like humans - and also in the *absence* of organic matter, such as the interior of a space ship or a fusion powerplant. This is highly suggestive that the xenomorphs are able to harness the electrical or other energy available in such environments in order to extract carbon in the form of carbon dioxide from the atmosphere in order to grow in the apparent absence of 'food'.
The observed behaviors and 'life cycle' of xenomorphs show that they are as much terror weapons as bio-/nano- weapons. While the trait of requiring biological hosts is a limiting factor on the growth of their population, there are more efficient ways that a designed bio-/nano-weapon could achieve the goal of exterminating large animal-like beings that don't involve growing macroscopic xenomorphs.
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Based on the internal evidence of the first two Alien movies, there are suggestions that the Alien Xenomorphs are not "evolved" creatures at all, but are somehow the products of an alien biotechnology.
If this is true, then it not only explains a lot about the behaviours of the Xenomorphs, but also suggests why the blood is so acidic: it is an electrolyte for an alien biological "battery".
If the Aliens, especially the drones and warriors, are completely self contained then there is no need to develop different species to operate in different environments; they will continue to function in vacuum, poisonous atmospheres, underwater or indeed anywhere they can gain a foothold into an ecosystem and begin capturing beings to use as hosts for the next generation. (You notice there is little indication that Kane [John Hurt] was actually suffering from the alien chest burster consuming him or the nutrients from his blood during incubation, it just mechanically burrowed out when it was ready to begin its life cycle).
So in a secret lab somewhere among the stars, a culture created a mobile, self directed and self reproducing weapons system to overwhelm alien ecosystems to meet whatever needs the creators had in mind.
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What about facehuggers, nobody mentions those things. I think they are a different species of creatures, they carry the egg, plop it in your mouth and let it evolve. Then when the job is done they run back to the nest to get another one. It’s symbiosis, the aliens get their young nurtured and the facehuggers are probably groomed and fed to keep them healthy and alive.
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I have devised an alien species for a universe I am working on. They originate from the same planet as my high-pressure creatures ([What would happen to a high-pressure creature in a low-pressure atmosphere (50atm)?](https://worldbuilding.stackexchange.com/questions/32159/what-would-happen-to-a-high-pressure-creature-in-a-low-pressure-atmosphere-50at/36253#36253)), but can survive comfortably in a much broader range of environments due to their robust nature (they have survived nearly every mass extinction that the planet has to throw at them and can even survive for extended periods of time submerged in boiling water, freezing water or exposed to the vacuum of space. Think of them as being a little like tardigrades).
Although they did evolve on this particular planet they have since been transported around the universe and are currently taking up residence inside of ships and space stations that are made of metal.
The idea behind them is that they are essentially a pest species - not dangerous to any organic life form, but making their living eating away at the hulls of such ships and stations, often causing massive damage and even hull bursts.
They possess a tough exoskeleton made of aragonite (like a chiton) and bear a vague resemblance to some kind of arachnid or crustacean. Is such a creature possible? Can any biological organism (carbon-based or otherwise) survive by chewing up metal, and metal alone?
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There are many kinds of bacteria that [damage iron](https://en.wikipedia.org/wiki/Microbial_corrosion) as they grow by producing various kinds of acid, such as sulfuric acid, as waste. At least one kind of chemoautotroph, *[ferrobacillus ferrooxidans](http://www.jbc.org/content/238/10/3453.full.pdf)*, actually uses the oxidization (rusting) of inorganic iron as a primary energy source. So yes, an organism that eats metal is certainly possible.
As you might imagine, there isn't a whole lot of energy to be gained by rusting iron, so I wouldn't expect to see high-energy organisms (animals) chowing down on metal. A contagious, corrosive mold would certainly be a threat to space travelers though, and isn't that far-fetched.
If you want to have the creatures be arachnid-like, perhaps there could be a form of symbiosis, where the animal 'farms' the iron-eating mold by spreading its spores, goes into hibernation for a while, and then harvests the mold after it has spread.
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Energy is not the only reason to eat stuff. Metal may be a bad energy source but it makes a decent building material.
At the crudest you could have creatures that just break up the metal to make homes, similar to a [caddisfly larvae](https://en.wikipedia.org/wiki/Caddisfly) making cases or a [paper wasp](https://en.wikipedia.org/wiki/Paper_wasp) making its nest.
You could also have something like a mollusc or crustacean like that consumes the metal to make its shell/exoskeleton .
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It depends. On Earth, when the atmosphere was a reducing one, before the first [Stromatalites](https://en.wikipedia.org/wiki/Stromatolite), the seas were full of iron, dissolved into seawater. Consuming iron in solution was possible at this time. Many organisms lived in the sea, albeit very simple ones. Stromatalites began photosynthesizing, in the shallows, and wiped out those other organisms with oxygen, but this took a couple billion years. Those organisms were anerobic, but they definitely thrived in the iron rich seas. So it's not only possible, it happened. Hell, *we* eat iron, we use it to bind oxygen, as hemoglobin, just in compound. Certainly aliens might.
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> Can any biological organism (carbon-based or otherwise) survive by
> chewing up metal, and metal alone?
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This is a hard no. Apart from being poor fuel source, biology requires a number of non-metallic elements. That said, you could make your creature far more reliant on metal as a part of its biology.
## Your creature could be based on limpets
Limpets are a kind of mussel who's teeth are made of an iron rich super materials called goethite. Limpet teeth have evolved to be stronger than stone so they can spend their days grinding away at rocks looking for microbial snacks in the pores. Apart from being one of the strongest substances known to man, goethite is made mostly out of iron.
For purposes of your species, these pest animals have taken goethite one step further and decided not just to make their teeth out of it, but their whole exoskeletons too. This would make anything containing iron worth consuming not necessarily for the caloric value but because it needs the extra iron to grow its shell.
The best thing about it for your purposes is that it would further reinforce the idea of your pests being nearly unkillable. Not only is goethite much stronger than aragonite, it is even stronger than spider silk or kevlar. So, apart from being resistant to hot, cold, etc. they could also be able to shrug off small arms fire if you make their shells thick enough.
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After doing some research to find natural resources in a swamp, I found that a swamp wasn't really able to do anything beyond it being good for fish growth, as a sort of natural water and air filter, and as a place for some iron ore (hematite) deposits as water flows through.
Now, naturally there would be different animals than in a normal swamp,. and it would be more dangerous to the layman, I'm looking for natural resources, something with magical properties, or some 'unobtainium' (gold, silver, mithril, etc., etc.) that makes sense in your standard fantasy setting.
What would reasonably be found within a swamp that would make it a valuable asset worth fighting over?
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[Peat](https://en.wikipedia.org/wiki/Peat_swamp_forest). Peat is a precursor to coal, and a valuable [fuel source](https://en.wikipedia.org/wiki/Peat#Characteristics_and_uses) in its own right. Prehistoric people may have fought over it for this reason alone.
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## Exotic Flora/Fauna (Plants & Animals)
### Biodiversity
Generally jungle/swamp regions have higher biodiversity. So if you need or want exotic biological materials (e.g. for potion making), then the swamps could be very valuable indeed.
### Mineral Wealth
Generally mining for minerals in a swamp is a losing proposition, however, a couple of exceptions to this rule are known.
**Gold Mine**
If the swamp filled/flooded an extinct volcanic caldera, much mineral wealth might lie below the swamp. A formation similar to that described exists in the [US state of North Carolina](http://www.osti.gov/scitech/biblio/6887875-geology-flat-swamp-mountain-caldera-related-rocks-carolina-slate-belt-central-north-carolina) and was the source of the [only major gold mining on the US East Coast](http://www.us-coin-values-advisor.com/charlotte-mint.html#Gold).
**Iron (et al) Mine**
Furthermore, biological action in some swamps concentrates elements like iron ([see bog iron](https://en.wikipedia.org/wiki/Bog_iron)).
## Strategic Location
If for example, two major landmasses are connected by a swampy land bridge, then it isn't so much the swamp as the location that you will want to keep.
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**Mythical treasure**
There might be some kind of myth that exists that says that there is valuable treasure in the swamp. Therefore, people would spend days searching the swamp for the treasure.
**Lumber**
Often swamps contain trees. From trees comes wood/lumber, probably one of the most useful items you can have in the construction of a structure or a tool. Obviously, wood could make the swamp a good spot simply because trees don't grow in many places outside of the swamp.
**Water**
Maybe the surrounding area is a desert that receives very little rainfall and has no natural bodies of water. Swamps often contain water, although fresh or not remains to be seen, and this watered could be filtered or drunk, depending on whether it is saltwater or freshwater, and whether it is contaminated or not.
**Animals/Plants**
Perhaps that type of alligator that lives in the swamp has hardy meat that can last for days without rotting. Perfect for tribal dinners. Maybe that rare petunia-like flower in the swamp has some divine medicinal properties. You might just want to harvest all of the flowers from the swamp.
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There's always the archaeological angle — ruins buried under or overgrown by the swamp, which could be attractive for purely material reasons, such as rumoured/actual solid gold idols/sarcophagi, as has already been mentioned by fi12; or if you're going for a magical angle, devices of incredible power or caches of forgotten knowledge.
For a less pulpy feel, it could just be the ruins themselves that are of some deep significance — an ancient holy city (because we know all too well that these tend to cause conflict), or the ancestral capital of a nation gripped in some hysteria about former imperial glory — consider the stories of Saddam Hussein developing an obsession with the Babylonian empire. While confirming that connection I also learned that [Saddam Hussein did actually drain a marsh](https://en.m.wikipedia.org/wiki/Draining_of_the_Mesopotamian_Marshes), only for much more mundane reasons: either to reclaim arable land, or to divert the water towards some people he felt like persecuting.
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The value of things found in a swamp ***worth fighting for*** depends on:
1- the size of the swamp.
2- the location of the swamp.
3- the information/technology level of the people in the world.
These are the things which are worth fighting for, for a modern day swamp and modern day technology level. Edit them according to the technology level of the people in your world.
**1- Rare/Valuable Fossils**
[La Brea Tar Pits](http://www.tarpits.org/) are one of the richest source of highly valuable fossils in the modern world. Thousands of fossils have been discovered and excavated from these tar pits and thousands more are in the process of excavation. Notice that these tar pits are solid ground now-a-days, but in your world, you could have the fossils buried in the depths of a (large) swamp.
**2- Route To Ore/Mine**
There is a goldmine in an area and long ago some medieval ruler started to dig it up for gold and later had to stop work because of a war or geographical changes. The mine is still completely intact underground and there are large quantities of gold still present there. On the entrance of the mine, now there is a large swamp! If two or more tribes/groups/companies know about this, they will definitely like to invest their resources for claiming the ownership of the mine.
**3- Home To Rare Migrant Wildlife Species**
There is a species of very large and beautiful bird which is very rare. These are migratory birds and migrate between two continents. In this continent, these birds only nest around a specific area for laying eggs and settling for a few months. This area is in the form of a swamp. The feathers of these birds are highly prized as ornamental objects and nobles are willing to pay high prices for buying one of those birds as a pet. Once again, different tribes/companies would have their eyes on the ownership of that swamp and would not hesitate fighting for it.
**4- Water Properties**
Let us say there is an ore of some rare mineral under the swamp and the water of the swamp has immense medicinal properties (cure of some otherwise incurable disease). Even with the technology level of today, you cannot produce that mineral compound easily in the lab and the swamp has large amounts of that mineral dissolved in the water. I'm sure pharmaceutical companies would not mind waging proxy wars in the area for claiming ownership of that swamp and its healing waters.
**5- Historical/Religious Importance**
This is self explanatory. The swamp might have been home to some saint or some mythical creature in the folklore and having ownership of it is believed to bring goodluck and prosperity.
**6- Important Trade Route**
Let us say that the area *around* the swamp is an important trade route and any village/tribe who has control over the swamp can put their war boats/canoes there and tax all caravans. Every tribe/city around that swamp would want to have their control on it and would not mind going to a war for it.
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Right now the Earth rotates around the y-axis so East and West replace one another. What would the affect be on Earth's seasons if it rotated on either other axis?
The first is the Z axis, pointing from Earth to the sun so that South and North swap places by going through East and West. The second option is the X axis, a tangent on Earth's orbit. This has North and South flipping over the Equator.
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Your Z-axis and X-axis are actually the same, the axis of the Earth stay fixed in space while Earth orbits the Sun, resulting in an alternating pattern.
* The Sun is zig-zaging over the sky in circles most places at the Earth, if you are close to the equator, the amplitude is high.
* All places on Earth would have the Sun in zenith at least once a year.
* All places except for the equator is going to have a dark season.
* Midnight Sun at least once a year in all locations, except for the equator that has two seasons of day-and-night twilight.
* Actually more overall solar insolation of the poles than the equator, making them the **warmest** region of Earth.
* Almost all stars are visible from all places on Earth during the year, not just limited to a southern or northern hemisphere.
Illustration of the Sun's motion across the sky:
[](https://i.stack.imgur.com/wk9zK.png)
In other news, the magnetic field is screwed up, so we are going to have aurora and cancer everywhere.
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Tilting the Earth's axis by 90 degrees will have the same effect on the climate as Uranus, with alternating poles having extended "summers" and "winters" while the equator will be in twilight during this time. In the "spring" and "fall", the poles will be dark while the equatorial regions will be in sunlight.
[](https://i.stack.imgur.com/7SmXZ.jpg)
Overall, because of the size and orbital period of the Earth, I think this will suppress the formation of ice caps and polar regions. Since there will be sunlight 3/4 of the year striking both poles, the period of total darkness will be rather short, and the Earth's atmosphere and oceanic currents will probably provide enough heat to keep the region simply covered in snow rather than ice caps.
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The other two answers address the "rolling" scenario quite well, but I'd like to point out one glaring error you made in your reasoning: the Earth *isn't* rotating along the Y-axis. It's rotating on an angle.
Now, of course, you know that. But the important point is that *this causes the seasons*. If Earth was rotating exactly around the Y-axis (with respect to the orbital plane), there would be no difference in climate due to orbital position.
As you let the rotation axis fall away from the Y-axis, you get more and more seasonal weather, up to the point where the rotation is aligned with the orbital plane (it doesn't matter in which direction - that's just an offset to when each season starts, but the effect is the same).
For additional points, changing the rotation rate can give you more to work with. If a day takes half a year, it's going to have a huge effect on the seasonal variations - it might be interesting to explore a scenario where the rotation is a bit more tilted and slowed down. Venusian weather and climate is pretty interesting, in part due to its slow rotation and massive atmosphere; while the planet's day is longer than its year, the *clouds* make the trip around in measly four Earth days.
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I guess life would be pretty much constrained to the equator regions. However, during the periods when the poles points towards the sun, the very hot sunward climate will very violently clash with the very cold climate on the other hemisphere. This is unlike the current polar climates - while we currently (in real life) also have a six-moth summer period at each pole, the shallow angle at which the sun provides heat and illumination is about nothing compared to the situation where the pole points directly at the sun. Imagine tropical climate there, but not for half a day with a cooldown in the night, but with heat building up increasingly for several months.
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I've got a group of humans who believe as a central tenet of their religion that humans should be as physically perfect as possible. In pursuit of this goal, they've spent a few hundred years applying an intensive program of genetic engineering and positive eugenics to their population. They've got a few hundred years worth of technological advancements over the modern day, and have a good grasp over the principles of genetic modification, though mostly of the 'modify the existing traits of an organism,' rather than the 'create a new creature in a petri dish' variety.
Their genetic engineering doesn't introduce any new paradigms compared to what we have today, but allows for much greater specificity in its manipulation. New genes can be precisely inserted into specific points of the genome, with manipulation capable of being applied to a single strand of DNA. Knowledge of genetics, of course, has also been significantly developed over the centuries. Geneticists have a good understanding of what most of the individual genes in the human genome do, though research over why a specific set of nucleotides results in a specific phenotype is ongoing.
The eugenics program is state run, and has essentially complete control over all reproduction for this group of humans. They decide who can reproduce and with who, and leave nothing to chance. Embryos are produced in lab facilities where any genetic defects can be eliminated and specific traits can be added.
Their government, which is one and the same as their religious hierarchy, has decided that 'physical perfection' means being as good at combat as possible. Their combat is similar to modern warfare, but with improved weaponry. Powered exoskeletons exist, but are expensive and only extensively used by top level commandos. There may be some hand to hand or melee combat, but as in the modern day, ranged weapons control the battlefield.
Battles in the future mostly take place either on space stations with artificial gravity or in extremely dense urban environments of megastructures. Combat in these environments mostly takes place at fairly close range, with rooms, doors, passageways, and crawl spaces constricting movement and field of view. This, of course is not a hard and fast rule, and a good soldier is expected to be able to fight anywhere, in confined or open spaces and with or without gravity. Philosophically, the society is trying to perfect the human body, so they are uninterested in creating soldiers who are built to be specialists in only one environment.
Within the scope of what is attainable in a few hundred years of genetic engineering, what general body type that would be most beneficial for a soldier? Huge and muscular? Small and lean? Small and stocky? Somewhat average?
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My answer is going to focus mostly on heightened senses. I think psychical build would be a lean 230-250 lb build (Like an NFL running back). But with guns you just need to be quick and strong enough to move with equipment, you won't be sprinting into battlefield.
Senses alone can change everything, especially ontop of the psychological level as in @Dan B post.
**Hearing**
Lets first say the one of the genetic mutations would be allowing soldiers to use their vocal cords well below and above normal hearing capabilities (Tim Storms can reach notes as low as G-7 (0.189Hz)). With extremely heightened hearing, it could be a form of communication. As when elephants flap their ears and produce sounds lower than what a human can here or produce a high pitch thousands of decibels above normal hearing. With such control over voice and hearing, a fraction of a decibel could be a different command. Not mention the ability to hear conversation from distances away, possibly hear conversations through walls! It's hard to say the limitations of a genetically modified ear. Also echo location (Like some blind humans have already started to perfect) would be possible now. This would make water no longer a concern if it came down to it.
**Smell**
This can come in handy for smelling out bombs! Dogs can do, now can these super soldiers. Also like dogs, the smell can be used to track people, follow their scent track. With smell, it would be easy to identify your fellow soldiers. Also humans release hormones when they lie, so you could smell someone lying and take proper action.
**Sight**
Sight would be able to be adjusted, 20/20 vision is no longer perfect because eyes would now be able to adjusted to need for varying distances. The ability for eyes to follow objects would be like watching a gunshot in slowmotion. One of these soldiers could slice a bullet out of the air with sword with the abilities they have! There is possibility of being able to see better colors, seeing in the dark and seeing in different spectrums!
**Touch**
The ability to feel vibration in the earth would be great help in combat situations. You could feel footsteps of people or vehicles driving towards them. Also touching anything in the world would be like reading brail. So every object touched would be like fingerprint in the world!
**Taste**
Like a snake you can taste your way around! I think this will also fall under being better because smell is better.
(Sorry the list got shorter towards the end! I'll edit later, but I have to go for now! If any one wants to add comments that would sound cool for super senses I'll add them in when I pop on later tonight!)
There is also other sensors that could be added that other animals have that humans normally don't. Like detecting electricity, infrared, accelerated perception(Basically slowing down time in the soldiers eyes) maybe comes with heightened sight? Just extra thoughts.
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If these people just wanted a society that was good at conquest, they could have engineered themselves to be smart and good at cooperating with each other, and they could have spent their research money on drone warfare. But that's not what they want. They want specifically to make all their citizens individually good at combat. That's going to lead them down a dark path.
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I'm sure it's not hard to increase a human's strength genetically. It's likely not that useful, though, since ranged weapons control the battlefield.
Infrared vision might be more useful, but it might be harder to do with genetic engineering (I don't think there are any animals with infravision to use as a base for the genetic coding), and even without infravision the soldiers could just wear night vision goggles.
The soldiers will certainly have improved reflexes and accuracy.
More valuable -- and this is the dark part -- would be to change the soldiers' psychology. People aren't mentally equipped for war. Most people have strong inhibitions against killing, which we have to train for a long time to overcome, and even after doing that we get nightmares afterward. Humans also don't like risking our lives: if we live in fear for too long we get PTSD which can be crippling for the rest of our lives.
A genetically engineered soldier might have modifications to make them more willing to kill, more willing to risk their lives, and less bothered by it afterward. Then they might need other modifications: everyone on their "side" might have some pheromone they emit that identifies them as an ally, and the soldier isn't willing to kill people after they've smelled that pheromone on them. The soldier might also get some sort of modification to make them more willing to obey orders -- perhaps that's linked to a different pheromone, which is emitted by the leader caste?
(This also leads to interesting roleplaying options: if your players research the soldiers' genetics, they can discover the pheromone system and use it against them.)
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> “Amateurs study tactics, professionals study strategy, masters study logistics“
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A skirmish is won by having the better tactics. A battle is won by having better strategy. But a war is won by having better logistics. So the ideal soldier would be one which has the least logistics requirements.
* Resistance to hypothermia.
* Resistance to high temperatures.
* Not requiring much sleep and if they do need sleep, allow them to sleep without requiring much comfort.
* Able to consume water and food which is rotten or contaminated by microorganisms. Maybe even being able to gain nutrition from commonly occuring plants (like grass or tree leaves).
* Not requiring much medical care when they get wounded (fast healing, high resistance to wound infection, high pain tolerance)
* Able to walk long distances without tiring or getting blisters (can be trained, but a natural deposition would still help).
* And no psychological consequences when having to endure any of that for an extended period of time.
Many abilities you would consider useful in actual combat (super strength, super sight, super aim, super hearing, super toughness...) can be achieved with high-tech equipment and require no biological modifications.
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"what general body type that would be most beneficial for a soldier? Huge and muscular? Small and lean? Small and stocky? Somewhat average?"
The [average Navy Seal](https://www.quora.com/Who-would-win-in-a-heads-up-hand-to-hand-battle-32-NFL-running-backs-or-32-Navy-seals) is about 5' 10" and about 175 lbs. You do not need the bulk of a running back (5' 11", 215 lbs) to make a really good warrior.
The main changes would be mental. Situational awareness is huge in any battle, and armed with the same weapons, i'd place my bet on the warrior with better situational awareness any day. That means a huge capacity for four dimensional thinking. Along with this, linear thinking would be heightened. This builds into the situational awareness, but it also adds to their capacity for strategy. Basically, they would be bred to be geniuses.
The other major genetic change would be in healing capacity. They would be genetically engineered for the fastest recovery time. This does not just help when they get wounded. It also means that a hard run through a forest takes less of a toll and the solider requires less rest before they are back on their feet and at 100%, ready to fight.
Another major genetic change would be in nerve conduction speed, and signal processing - i.e. reflexes. This race would be wired like a tight spring, but with the mental control to manage reactions.
Just shooting from the hip, so hopefully this adds a little to the other answers.
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A few things that have been missed in other answers. If this military situation is the standard through-out the duration of the genetic engineering, and there is a practical pressure to actually achieve more efficient human combatants than this is what would happen. (If either of the two previous statements does not hold true this might not happen)
Concentration of fire power. Most conflicts “ take place either on space stations with artificial gravity or in extremely dense urban environments of megastructures”.
Space is a premium. Small shorter soldiers can pack more fire power into smaller areas. This would lead towards a general trend downwards in size. In addition if you have to transport your troops into space there is a huge cost to this. Smaller lighter combatants make this more efficient. Especially over long space flights since they require fewer supplies. Tall soldiers would also be useful to fire over their smaller counterparts, but they would be narrow and lanky. Again fitting more into a small area.
Both of these traits can make the soldiers smaller targets in many situations as well. There is also a cost savings in protective equipment. Small combatants require less materials to build armor and uniforms for. A small person inside of equal sized power armor as a large person leaves extra room for extra equipment. More munitions, or larger fuel reserves.
Patience and the ability to sit motionless for hours. With the super abilities others have mentioned an ambush will have to be perfectly silent and still.
Adrenal control and tolerance. Adrenaline does wonders to physical performance.
Memory and intellect. The urban chaos of the mega cities means any prolonged combat becomes a maze puzzle that whomever solves better wins.
Metabolic control. Being able to slip in and out of a coma/hibernation at will means supplies in a space ship or space suit can last longer. Smaller ships are harder to identify. What if a few dozens space suits where sent adrift 3 months out to be the first wave attack?
The end result is an ideal army trending towards small wafe like or child like midgets/dwarfs. If you keep the negative health affects of dwarfisim you even have soldiers who will die in their prime. Knowing they will die soon helping take away their fear of death in combat. Also saving on medical expenses since you don’t have any long lived veterans’ medical expenses to support.
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It's easier to Dodge a bullet!
In order for the reaction time to be fast enough to avoid a bullet, we will have to increase the speed of nerve conduction from a certain speed, measured in meters per second, to a speed close to the speed of light. Metal cores and sheathed nerves would meet this requirement. Then we will have to replace the slow diffusion signaling mechanism of the nerves with something much faster... So instead of relying on chemical diffusion, we could have a mechanical connection between the nerves. This may be a mechanism in a transmitting neuron that, upon receiving an appropriate electrical signal, rotates by a certain amount and that is physically connected to a sodium gate that also relies on rotation to be opened. Mechanical coupling means that the transmission speed will not occur at the rate of chemical diffusion ( the average speed of a nerve impulse is), but at the speed of sound in the connecting rod. ( the speed of sound is )
By reducing the reaction time of the brain and nerves, the main limiting factor will be the muscles and body. Mammalian muscles are relatively slow. Although there are some things that can be done to speed up the speed of muscle contraction and reaction time. The problem is that it is unlikely that the muscles will be able to contract at a rate much greater than we have in normal muscle fibers. However, there are alternatives.
The nature of the muscles is such that they should contract gradually, a few micrometers at a time, but when relaxed, they can stretch much faster by external forces. So to maximize the speed at which the limb can bend, we can increase the ratio of joint to muscle and joint to load, so that less effort is applied, but applied faster. In addition, in the directions most likely to evade, we can completely replace the muscles and replace them with a highly elastic combination of muscles and ligaments. In a stressful situation where rapid movement may be required, the stronger antagonist muscle will contract along with the weaker agonist muscle, stretching the elastic ligament. Then, if it is necessary to evade, the corresponding antagonist muscles can be deactivated, resulting in the stored energy in the elastic ligament being applied to the joint much faster than the muscles are capable of on their own. In addition, it would be possible to have both a powerful antagonist muscle and a smaller muscle-elastic ligament in each direction of movement to provide two "gears" for each direction of movement, slow and powerful, and weak but fast.
Yes, this Superman capable of successfully dodging bullets is unlikely to look like an ordinary person. After all, muscles have mass, and the smaller the mass, the easier it is to move. Instead, expect to see a creature with long, thin limbs and a thin body that looks more like a gray alien than a human.
However, despite its apparent slimness and fragility, this creature could not only Dodge with superhuman speed, but could also be an incredibly dangerous martial artist. Although its limbs could weigh half as much as the average human, it could reach a limb speed perhaps ten times that of a human. Given the ratio between the impact energy, mass, and speed equal to e = 1/2 MV^2, half the mass is equal to half the energy, but ten times the speed is equal to a hundred times the energy, for the total impact energy is fifty times greater than that of a human. This slender, lanky, and frail-looking creature could literally kill a man with a single blow.
Of course, this creature's adaptation requires it to be aware of a potential attack in order to evade it. When threatened, he crouched, and his muscles tensed, keeping his limbs half-bent as he stretched the elastic ligaments. He could see the nearest enemy's finger on the trigger, or see the flash of a shot from further away, and within milliseconds he could deactivate the enemy's muscles, elastic ligaments Contracting to take him out of the line of fire.
Of course, if this creature were caught flat-footed, it would not have the advantage that energy would accumulate in its elastic ligaments, and given the likely energy needs associated with keeping the elastic ligaments stretched, it would not be able to walk with them permanently pre-stretched. In this case, it would be much more likely that he would be hit by an incoming bullet, although he may be able to achieve a less serious hit.
If you still need to withstand a bullet hit.
That means that they are made of parallel fibers optimizing their ability to pull along their required vector. Along this angle, you can punish them all you want with a relatively small risk of injury. However, bullets tend to hit the muscles on the sides, which allows them to squeeze between the muscle fibers with relatively little force. If the muscles were woven more like Kevlar, they would be extremely difficult to penetrate. Unlike thicker or harder muscles, woven muscles will not significantly reduce flexibility, but you may suffer a slight decrease in the pull force, since you are no longer pulling straight.
Perhaps the best option for a natural armor that doesn't seem less human would be to strengthen your person's entire body with a Dura mater .
The Dura mater is the outermost protective membrane that covers your brain and spine. It is exceptionally strong, flexible, and made from irregular cross-woven fibers. A report from the new Jersey public health system shows that the Dura mater of rats can withstand 1.3 million Pascals of stress, which is a lot, especially considering their size. By layering the Dura mater between your skin and striated muscles, your person will look, feel, and move very much like an ordinary person, but when fired from a small-caliber cartridge, the Dura mater fibers will distribute the impact across a large cross-section of the muscles instead of allowing it to simply pierce between them. With distributed impact, your muscles can do what they do well and contract.
By distributing the impact over a larger surface, you would probably tear the skin, many bruises, and some serious muscle inflammation after being shot, but the bullet would be much less likely to be able to hit the main organs.
Astaxanthin ( having a predominantly red hue ( red pigment), similar to the color of watermelon pulp. ) is a type of mountain algae.
This type of mountain algae fully survives at low temperatures and interaction with ultraviolet radiation.
Having red skin color with astaxnthin pigments can help survive high levels of UV radiation.
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Most of what has been mentioned lis very valid, although I suppose there could be quibbles over what is more important; stamina or enhanced senses.
I suspect that the real payoff would be to enhance kinaesthetic senses and have the ability to control many of the physiological functions of the body as a way of overcoming combat stress and staying focused. Elite soldiers might not resemble running backs at all but rather svelte swimmers with the flexibility of gymnasts or dancers. Having high levels of control over your body also means the ability to stay still for long periods of time, not have to stop for a washroom break at an inopportune moment, conserve internal stores of water and energy etc.
Maybe we should be thinking in terms of something like a gunned up Shaolin warrior monk.
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I would suggest that things would progress towards many of the attributes featured by the [Adeptus Astartes](http://wh40k.lexicanum.com/wiki/Space_Marines) or Space Marines of the Warhammer 40,000 universe. These soldiers are physically larger than standard humans, although that is mostly to inspire fear/awe on the battle field, provide greater space for their extra organs and allow them to operate heavier weapons on the field.
In addition to size (which may not be a huge advantage) they have:
* Increased Strength
* Hightended Senses
* Faster Reflexes
* The ability to withstand poisons and toxins
* Redundant organ systems
* Improved healing (no point in second heart if arteries don't seal off around damaged one, etc)
* Solid or near sould chest cavity to better protect vital organs
* Thicker epidermal layers to help act as living armour
* Fanatical Loyalty (helpful for a religious government)
* Limited Self Replication Ability (cannot have them go rogue and breed some rebels or be trained by an enemy)
There is a page detailing the [creation of a Space Marine](http://wh40k.lexicanum.com/wiki/Creation_of_a_Space_Marine) that lists the organs and implants that are added. With sufficient genetic fiddling it should be possible to get many of these to form within a creature anyway. The main interest is the list of attributes you end up (see above) rather than how they are achieved in a particular fantasy universe.
The bit about breeding limitations is going to cause a question over whether you have a warrior cast that are effectively mules or if everyone in society is going to be similar. If it is everyone then heightened intelligence might be beneficial to help with tactics and production of arms, etc.
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***All of the above.*** In addition to the general improvements applied to everybody:
* snipers would be engineered for precise hand-eye coordination and mathematical intelligence
* infantry grunts would be engineered for the speed, strength, and stamina to carry heavier weapons and armor
* commanders would be engineered for holistic tactical/strategic intelligence
* submariners would be engineered to survive on less food, water, and oxygen
* pilots would be engineered not to get cramps from sitting in one
position for extended periods
* ...
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I would suggest looking at the modifications done to Colonial Union soldiers in John Scalzi's *Old Man's War* (a superb book, by the way). In it we see interesting examples of many points brought up in other answers. For example:
(mild SPOILERS)
* the soldiers' skin is green so as to absorb chlorophyll for energy
* cat eyes
* spliced wolf DNA for loyalty purposes
* seriously increased senses/reflexes/strength/neurological performance
* improved stamina, lung capacity, and resistance to the elements (even, if I recall, a limited ability to survive in the vacuum of space for a short time), and they require significantly less sleep than a normal human does
* a healthy sex drive + sterility
* a powerful computer/PDA woven into the soldier's brain and networked with other soldiers that improves the clarity of the battlefield, and provides instant, non-verbal communication among soldiers
* oxygen-carrying nanobots in place of blood that can clot immediately and also burst into flames if an enemy is covered in a soldier's "blood"
* denser/more durable muscular-skeletal system, so that they can carry far more weight for far longer without suffering injury (the majority of health problems among infantrymen today is the fact that they have to carry about 100 pounds during a patrol, for example, which often result in spinal injuries, stress fractures, and so on)
* because recruits are all over 75 years old at enlistment, they come equipped with more life experience and mental stability that helps them deal with PTSD and the other effects of warfare
* soldiers' bodies are able to swiftly regrow limbs, organs, etc., when sent to a medical facility (and can be given crude replacement limbs quickly via battlefield medicine, if I recall correctly)
* resistance to poison, viruses, parasites, etc.
Now, I am, of course, not advising you to just lift wholesale ideas from Scalzi. But, as we see with the chlorophyll skin, wolf-spliced DNA, etc., the sky is the limit for your group of humans, and nature can provide some awesome and creative suggestions for them.
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There's a number of cyberpunk role playing games that have rules and options for enhancement. One answer mentions Warhammer, there's Shadowrun for the big ones.
Senses are top of the list, so is anything that improves reflexes and reaction times,
and answers along those lines have already been added.
However, you still want to train those super soldiers - none of the physical improvements listed help much if they don't know how to operate their equipment, guns, etc.
There's plenty of evidence genes are very influential in learning. So I would suggest one of the most interesting aspects of gene manipulation would be to change brain physiology to be perfect for military training and making use of the added information. How about a tactical sensory processing brain center to improve situational understanding? The brain improvements to ensure your soldiers don't just get something out of training, but are all elite fighters afterwards?
Skill doesn't necessarily trump equipment, more the other way around, but greater skill + better equipment trumps better strength or other physical aspects in my opinion: as pointed out before, when you have guns, no need to be super strong or even athletic.
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Humans are already pretty adaptable, so without changing the major traits that make them so adaptable very much.
If ranged combat is the more "perfect" combat then the arm would most likely grow longer for more leverage, their eyesight would improve, better accuracy, the muscles in their arms would switch to fast-twitch muscles, and the torso should twist farther to allow the arm to go back farther.
If hand-to-hand combat is the more "perfect" combat then the bones would become stronger, their perception would speed up, their their muscles would have to strengthen, their endurance would have to grow, reflexes would have to speed up, thieir agility would increase, their nails might even grow and harden into claws for a more damage.
If stealth is the main priority possibly chromatphore skin, pads that quiet their footsteps, night vision, probably retractable claws, faster reflexes, spacial awareness, echolocation, much at better at planning ahead and improvising, faster thinking, and smaller build
If adaptability is priority then gill like structures, bigger spleen size, enhanced tissue oxygen delivery, probably a membrane connecting limbs for gliding similarly to flying squirrels, thinner calves and ankles for running, oily tears to see better underwater, rib number and flexibility increase, echolocation, possibly gecko like toe pads (didn't work the math for them), and a second denser eardrum.
All should have heightened senses and maybe even new senses, need less sleep, have a stronger stomach, a better immune system, much faster healing, higher pain tolerance, better spacial awareness, night vision, better at using the oxygen at low oxygen levels,can use food better, better strategists, extreme loyalty, identic memory, less hesitation to kill, better at handling the psychological aftermath of killing people, and the neural change to keep all of it in control.
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The carnivore/omnivore/herbivore army from this [question about herbivores](https://worldbuilding.stackexchange.com/questions/25724/what-good-are-herbivores-in-an-animal-army) has reached the battlefield and the opposing army is a collection of large, scaly, occasionally feathered animals that no one has seen before. **Dinosaurs!**
Each army has an equal number of carnivores and herbivores in each weight range, so a comparable number of fox sized predators, a comparable number of lion sized predators and so on. On both sides, smaller combatants are more numerous than larger combatants. However, the dinosaurs have a collection of super-heavy carnivores/herbivores that the mammals have no equivalent to. Examples of the super-heavies are the tyrannosaurus-rex at 18,000lbs/8164kgs and the triceratops at 28,000lbs/12,700kgs. The mammal's "super-heavies" are the grizzly at a pitiful 1400lbs/635kgs and the African bull elephant at 15,000lbs/7,000 kg. The only consolation to the mammals is the dinosaurs only have a handful of their super-heavies to field.
The dinosaurs have the same uplift as the mammals (ie, human intelligence but no tool usage and vocal communication regardless of actual physiology). The dinosaur army is composed of dinosaurs strictly from the Cretaceous period. A helpful list can be found [here](http://dinosaurs.findthedata.com/).
Handling the logistics of how to feed so many carnivores and herbivores are out of scope of this question. (Yes, wars are won on logistics but that's a different question). Also, why these two armies are fighting is out of scope.
*As the mammal's commander in chief, how would the mammals counter the super-heavies fielded by the dinosaurs?*
This is [science-based](/questions/tagged/science-based "show questions tagged 'science-based'") question so links to official sources are recommended but not required.
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Most of the super-heavies could be hindered by pot holes, very uneven ground. One of the most dangerous things for a brachiosaurus is a broken leg. It is pretty much done at that point. These animals can't really jump and pits would either get them caught or possibly break important bones.
Having only two legs the Tyrannosaurus might be a bit harder to catch in such a trap but should they be caught they will be just as disabled should they fall in or break a leg.
This also leads to the tactics for attacking them. large mammals going for the legs and joints of the ultra large. breaking a leg will take them out of the fight. (would be a similar problem should an elephant break a leg...
Of course mammals fighting Dinosaurs might have a bit of an edge should they commence the battle in a winter wonderland...
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Why exactly are we limiting mammals to currently existing species? The mammoth could weigh as much as [12 tons](https://en.wikipedia.org/wiki/Mammoth), the Indricotherium was even [larger than most dinosaurs](https://en.wikipedia.org/wiki/Indricotherium)! The greatest of mammals could certainly hold their own.
That said, limiting it to current animals -- why not swarm the larger enemies? Cooperative hunting is one of the hallmarks of mammals.
Mammals are also well known for killing far beyond their weight class -- we have weasels that kill rabbits ten times their sizecougars that kill animals more than four times their weight and polar bears killing whales!
It's honestly a wild guess how mammals would fair against dinosaurs -- but don't count them as down and out.
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In a fair-ish fight, I doubt they'd stand a chance: sure, they be more mobile, but it's about angular velocity: if you have to outmaneuver me by running around me, you have to move much much faster than I need to just to spin around on myself.
So what is the right way to approach this problem? You can use their sizes against them to prevent the fight completely. We can summarize by "use the terrain", but for a few example:
* Fight in a narrow space, such as a series of caves/tunnels where they
have no way to enter the battle. Use choke-points (Thermophiles, anyone?)
* Use bridges: if you manage to re-route your troops over non-massive
bridges, there is no way those would be able to stand a T-rex (think
of one of those stereotypical movies bridges set in the mountains
such as Tibet: a bear can cross it, a T-rex won't. Note that this may
exclude your elephants and similar-size animals too).
* Use crumbly/hard to maneuver on terrains: fight on the steep side of
a mountain, or somewhere very prone to landslide or sinking (snow,
crumbly rocks, mud, etc.). This may even score you some extra kill as
the T-rex falls on his comrades.
* Fight in water: Assuming that the dinosaurs don't have water-based
super heavies (in your example you only mentioned land-based ones),
fighting in (deep) water prevents them from accessing the battle
* Use air attacks: If you can manage to drop some massive nets from the
air on them, this will likely make them fall and immobilize them
* Hinder their mobility even more: use some fast land runners as the
balls on a bola (with a very sturdy chain), think two cheetahs
holding a rope in their mouth and tying up the legs of the T-rex. How
is he going to get free with his short arms (and no assistance from
his comrades)?
Another very valid option is that of psychological warfare:
* Bribe them: straight on, try to make them switch sides. Even having a
single one turn sides may be a massive hit to morale, and in turn
make the whole other army suspicious of the traitor's species,
hindering the battle collaboration/trust.
* Have some of your more "dino-looking" animals (Komodo's dragons? Crocodiles?)
infiltrate the enemy and spread rumors with the same intent of the
previous point, even false-flag some terrorism event in the ranks if
needed.
Finally, consider using "artillery-like" weapons. If you can lure the big ones in certain spots, given their size, they'll be easy targets for things like a provoked avalanche.
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I depends widely on the battle ground. My general feeling is that mammals are more versatile.
## Savanna/ plains
Other contributor seems to see this as the default scenario.
I'd say that a brachisorus with a human brain and agressivity is almost imposible to stop. Especially flanked with 2 T-rex and a protected by few bird to intercept eye-targetting bats.
DINO WINS.
dominance factor: 68.5%
## Somalia
As annalysed above, I don't think mammal stand a chance. So I take a bunch of [naked mole-rats](https://en.wikipedia.org/wiki/Naked_mole-rat) and stay underground until they get tired
DRAW GAME
Shame factor: 0%
## Forest/urban environment
Mammals can ensure a draw game. There is no way the dinnos will get my [orangutan](https://en.wikipedia.org/wiki/Orangutan) squad if I don't send them to combat.
By throwing stones (or standard fight if dino are crazy enough to get in the trees), Orang would wipe out any medium sized dino.
A big stone from a giant sequoilla would kill anything, but the dino commander would not fall in the trap.
Giant dino would have mobility problems. [African forest elephant](https://en.wikipedia.org/wiki/African_forest_elephant) and their tusk could take advantage of this.
MAMMAL WINS.
dominance factor: 62.2%
## Artic
*EDIT: More search needed*
## Mountains
Biggest animal would be nothing but sitting duck, here.
Some raptor-like dino could give a fight, but I can't see them win agains a mix of bear, Jaguar, or mountain goat
Above all, on very steep ground, 10 Homo-Sapiens with spears would genocide any herd of anything.
MAMMAL WINS.
dominance factor: 72.2% (four legged mammal only)
92% (If humans are allowed)
## Open air
A tricky one.
Birds are dinosaurs. And I am sure that no bats could outfight a modern bird.
But cretacean birds?
I just can't find example of big cretacean birds. And it seems that, compared to modern birds, they where poor flyers.
Yet, the body of small birds is something rather bulky. I am sure that many primitive birds could reach a 60km/h speed. 2 or 3 of such bird ramming a [Pteropus vampyrus](https://en.wikipedia.org/wiki/Large_flying_fox) would bring him down. Bird may even survive the collision.
DINO WINS.
dominance factor: 84.0%
## Open ocean
I summon 1 [sea cow](https://en.wikipedia.org/wiki/Dugong). As there has never been any fully aquatic dinosaur, I win!
Spinosaurus can swim, but 3 orcas would tear him apart in minute.
MAMMAL WIN
dominance factor: 100%
## Swamps
## sand dessert
## rivers and lakes
## small tropical island
## Corridors
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One of the hardest things to counter would be large carnosaurs hunting in packs. While we are used to seeing T-rex as a lone hunter in movies and SF TV shows, there is some opinion that they hunted in family packs (young T-Rex chicks would stay in the nest, but older ones were gangly teenagers with proportionally longer legs, and may have been used to chase down prey to the waiting adults hiding in a copse of trees. Being hungry teenagers, the young T-Rex acting as "beaters" would have a great deal of incentive to take part in a cooperative hunt...).
The best way to counter that would be to incentives the carnosaurs to turn on their own kind. The mammals would have to hide out and use scorched earth tactics to ensure the carnosaurs become very hungry. And just behind the advancing carnosaurs is an entire enticing array of steak on the hoof, steaks they were evolved to eat in the first place...
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If bats are allowed then all you need is a group of large bats (and flying squirrels/foxes?) flying around their ... eyes, fluttering their large wings, occasionally poking them.
Some monkeys/gorillas armed with pointed stones, climbing on them (jumping from backs of elephants/necks of giraffe to things like T-Rex and spinosaurus) could actually *kill* them by simply prodding them heavily along the vertebral column over and over again until the vertebrae are deeply damaged and ... (the details are too gory so I'd avoid mentioning them. It would be one of the most brutal and horrific, slow, disabled death).
Also you could deploy [Punji Sticks](https://en.wikipedia.org/wiki/Punji_stick) with venom coated tips in tall grass. Your troops must not enter that grass field and lets the enemy ...
What else do you want?
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Assumptions to challenge.
A) dinos do not forn a regular army...disorganized irregulars at best. Good chance theyll not cooperate readily.
B) dinos giant size is directly related to the atmosphere involved. The atmosphere was heavily oxygenated and they were pushed to their extreme size because of this. These dinos would be significantly smaller in our atmosphere, or reversely, mammals would likely be significanlty larger in theirs. Creatures like the woooly mammoth could be 10x the size when put into the dinosaurs world.
C) humanity is directly responsible for the extinction of the largest mammals on the globe. Cave bears for example were significantly larger than grizzlys, but we killed them all. The short faced bear fell to extinction as well...this north american beast was 900kg and stood around 12 feet tall. If you include extinct mammals, you will see larger sizes on the mammal side.
This gives me the impression that given the right set of conditions that gave rose to the dinosaurs would give rise to larger mammalian creatures as well and the mammals would infact have their giants.
Also need to define dinosaurs...there was a 3 foot long dragon fly species that would tear apart most mammals their size and could also include swarm tactics. Is that a dino? They were alive then...
Lets get rid of the assumptions and give the impossiblity that these creatures could exist together in these states...it really comes down to tactics of a semi 'regular' mammal army vs an irregular dino army. In open field, dinos win as there is little the mammals can do vs these giants (assuming no tech for the mammals). This means that the mammals need to engage in a guerilla warfare battle...hiding,striking, and hiding again. Mammals may also have an extreme night time advantage as im unsure on nocternal dinos.
Edit:
Mammals might be much better in water than their dino counterparts as whales tip the scale a bit. Sharks are the natural whale predator, however sharks are not usually considered dinosaurs. If you take a blue whale and put it into dinosaur atmosphere conditions, its possible the blue whale is the biggest creature out there. Also good to point out that some massive sea mammals died out prior to the indian subcontinent colliding with asia (theyd be 10 to 15 foot long eels like creatures comimg from a now extinct branch of whales that would dominate a shallow ocean enviroment though weak in deep waters).
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by making intelligence equal you basically guarantee a dinosaur victory.
your biggest problem is armor, scutes and scales are tough, dinosaur skin is going to be a lot better armor than mammals have.
plus dinosaurs have a much large pool of talent to pull from, the cretaceous is almost 30 times longer than the quaternary.
Finally in the end size is just too big an advantage in open combat, some of the armored sauropods would be nigh unstoppable to modern mammals. Or picture Ankylosaurus it weighs as much as an elephant but it comes equipped with both amazing armor and a killer weapon, and it needs it because there are many herbivores and predators much bigger than it.
mammals just are not designed to be big so the big ones are kinda fragile.
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Imagine that we one day invent an ansible, capable of near-instantaneous FTL communication, but we can not transport physical matter any faster than light.
Imagine also that we have gotten to the point where space travel is possible, but still massively expensive and obviously slow. We want to colonize other worlds despite this expense, but ultimately we must have some hope of these worlds leading to and expanding our economy to help justify such expenses; even if that economy takes a generation or more to build up after colonization starts.
However, a standard economy is nearly impossible: [FTL travel is impossible. How is interstellar trade possible?](https://worldbuilding.stackexchange.com/questions/17244/ftl-travel-is-impossible-how-is-interstellar-trade-possible) With the high expense of space travel shipping goods from A to B is absurdly expensive relative to the cost of the goods, and the lag time between shipping and arrival, measured in years if not centuries, means that anything other than raw materials would be outdated by the time the arrived.
However, information has been bought and sold for generations, information is power and thus is fungible asset! Therefore I'm wondering if an economy could be developed which exploited FTL communication to make paying for resources possible across worlds. Can a world 'buy' a shipment from another world by producing value purely through FTL communications, which they, then, exchange with the other world. Can a colony eventually refund it's investors that helped fund it's deployment through some sort of value generated on their home planet and 'transported' to earth through ansible communication.
For the sake of this question lets assume enough colonies have been generated that scientists has gotten lots of feedback about interesting astronomical entities from lots of colonies, and thus we no longer consider the information that a newly formed colony can send back about it's home world/system to be able to provide any significant insights or advancement to our understanding of science or the universe.
edit: one extra small detail. Assume that colonies, at least for awhile, are significantly smaller than Earth, and as such tend to have less cultural or scientific development than Earth, simply by virtue of Earth having well over 100 times the number of people to generate these things.
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As you said, information is the only thing that can be 'traded' with any reasonable return on investment. So there are several ways this could work. One even now 3D printing is becoming a big thing. So now you can send 3D printing plans for different items to be printed at different locations.
There will always be new scientific discoveries, and sharing these across the cosmos can help everyone. Being able to be in communication with any human outpost or ship would also help prevent minor despots from taking and keeping control (though it won't be fool proof just make it harder).
Though to be honest, it will be hard to regulate the information exchange beyond the first one of any interaction. Like the internet, much of the information will be free so it will be a strange new kind of 'economy'. More of which communities get respect for adding to human knowledge vs. untold riches.
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Fundamentally, an economic transaction (without actually transferring solid materials – gold, silver or other commodities of perceived value) is done by transfer of wealth backed by the promise of solid materials held by a regulating governing body (or in the case of the US, by fiat currency).
In the described scenario neither planet can transfer physical wealth.
But the bigger problem is that by the time a new colony is established, all of the technology and science used to send and set up the colony has been outdated by hundreds of years. So the colony would have a disadvantage of not being able to bring enough resources (physical and intellectual) to bear on any given area of interest to the home plant (at least for a very long time) to make transfer of information a likely source of income.
But, assuming that the colony does manage to produce something of value to the home planet, what would the colony spend it’s new found wealth on? The home planet would have to basically send all of it’s current technology to the colony just to bring them up to speed in order to give them a basis to produce the information commodity for sale back to the home planet, so there would be nothing to buy with this new found wealth.
The better value scenario is for the colony to essentially be the equivalent of an untouchable bank vault for information and servers that are (in essence) extra judicial repositories.
All home planet governmental organizations would be unable to coerce the colony to comply with requests for ownership information due to their inability to sanction the colony in some fashion.
Essentially you would have a “Swiss information” bank account on the colonies computers that would be outside the governmental reach of the home plant authorities, such a thing would be very valuable to criminal organizations and other wishing to hide stuff from the governments of the home planet.
In theory this “security value” could be translated to wealth that would be used to transfer information (of use to the colony) faster than it would otherwise be available.
For example, there is always a delay in publication (and commercialization) of research. If for example the topic was some form of biomedical research of interest to the colony (treatment for a disease that for some unknown reason is much more prevalent on the colony), it would be advantageous for the colony to gain access to that information much sooner than it would normally be released on the home planet.
This would form a basis of a functioning economy between the 2 planets and would not be limited to a binary planetary arrangement since you never put your eggs in a single basket or you’re held hostage by the holder of the basket, and each planet would have different challenges therefore different bits of information would have different values to the different colonies.
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There is one commodity which can be transferred as pure information: computation. Colony worlds can participate in an intra-galactic economy by selling computation time on their local computer networks. Raw computation may not be terribly useful, but specialized computation could be extremely useful. Some colonies might specialize in bioinformatics, while others specialize in manufacturing modelling. Colonies could thus exchange valuable information as a tradable resource.
For instance, a biologically diverse world might specialize in genetic manipulation, and especially how to tailor-make genetic codes for particular environments. Other worlds might employ their networks to design special plant species that thrive in their local environment, or to help them change their ecological balance in response to an accident, war, external dynamics, etc.
A gas giant world might be experts in fluid dynamics and can consult in the design and manufacture of all kinds of aircraft and seacraft.
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# Colonies
Due to the complexity of space travel, little colonies would venture far into the deep space. The closest stars and planets are already at more than 4 light-years away. On the list provided [here](https://en.wikipedia.org/wiki/List_of_nearest_terrestrial_exoplanet_candidates), we can see that planets outside our solar system are even probably more than 11 LY away.
Of course smaller colonies could be based on moons, Solar System planets, asteroids, etc. That could be closer.
But let us consider some possible colonies:
* the moon (~ 1 light-second),
* Ceres in asteroids belt (~ 24 light-minute in average),
* Pluto (~ 5.6 light-hours),
* Proxima Centauri (~ 4.4 light-years)
# Communication in economy
A fast communication is crucial in current international market. Bought are bought, loan are taken, interests are paid, and generally, money is transfered via computer lines. This is very important because invester for given goods or services may be at the other side of the planet, and the prices are set in real time. So investors have to be able to react at market fluctuation and transfer the money really fast.
How fast? Good question. I don't have a definitive answer, and as time passes, it is likely that computer will replace the brokers to some extend. But let's say that humans still check that the computer decision is correct. Humans need a minimum of 2 seconds to realise that an event is going to happen and react on it (I got that number when learning to drive ;-)).
We need the human factor to be a bottleneck to some extend. So if money transfer and current price can be obtained in a matter of a second, most of the current economy will function as it does now.
A note to computers/AI to deal with markets: that would change of course some of the following discussion, but it opens even more question, so we'll skip it for now.
Giving two examples, we could have the following operations that only rely on communication.
* A good is bought by an investor, and then sold again to a distributor. The investor never needed to actually get in contact with the said goods. A shipment of banana can be bought and sold several time on its way from Africa to the USA.
* Some local investors want to buy some products but don't have the funds. They ask for a loan to a bank or a financial actor. They never need to meet.
# FTL communication
Within a colony, or on Earth, FTL communication would not revolutionise the economy, as the limiting factor are the humans. So that does not change much from the current situation.
Between Earth and colonies. FTL communication would basically extend the range or the Earth market. Operations can be done as fast on the moon as on Earth, so no big changes there.
For the others, there is the question of how *F* is in **F**TL. I don't want to enter into the technicality of the bandwidth, protocol used, etc. Let's say you achive to communicate a relevant information 1.2 faster than the time the light need to effectuate the distance.
So you already need 20 minutes to send any information to Ceres. This sets the financial markets some 40 years back to (our current) the past. High-speed speculations and many financial tools used by the markets won't be available from the Earth. But you can still have an active part in trade, you just need more predictable goods.
To Pluto, you need more than 4 hours to send any order. You're too slow to actually influence the trade/currency market. Local investors profit from your slow reaction to make more profit. It is probably a good idea to have a dependent office on Pluto, who's in charge or daily operations, with slower fund transfer and strategy set from Earth.
To Proxima Centauri, 3 years aren't enough to send any information, so to get the current value of the market and place an order, you still need 7 years. The company producing the goods may be brankrupt by then. You need to place an office there, but even then, the communication is really to slow, not to have that detached office operating fully independently.
What I mentioned from Earth, could also be seen between the colonies themselves.
# Conclusion
It expands the local market to include neighbouring regions, but real economic communication does not get much improved with more remote colonies.
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*"Can a colony eventually refund it's investors that helped fund it's deployment through some sort of value generated on their home planet and 'transported' to earth through ansible communication."*
**Very unlikely**. The inability to exchange tangible resources means that the colony cannot export its surplus production. Given that the colony is likely to be resource rich but information and culture poor, the investment outlook is not good. Unless you come up with a plotline to superpower the colony information economy (like they can produce some super-comptronium and be the data centre for the earth) they will be a net surplus natural resource producer and an importer of services and information.
The surplus goods in the colony will lead to deflation in those sectors, their currency will depreciate against the homeworld and the price of imported information and services will rocket.
Ultimately any currency has to convey to the holder the right to consume, and consumption is synonymous with the dissipation of free energy (by eating food, driving vehicles, using google search etc). It is not obvious why long term terrestrial investors would invest in the colony since any claims on the colony cannot be used for consumption on earth.
A purely service/culture based exchange would likely end up driving bubbles and speculation before a final deflationary collapse. In reality economies need to be grounded in the real economy of physical consumption.
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You hint about information, and you forgot a very important sub-class of information which is strongly marketable… software and media.
As long as you have means of sending and receiving files, you can have a software and media economy.
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# Who says you have to trade physical goods?
We already have a pretty expansive marketplace of digital goods and a number of digital currencies to exchange. We would be able to trade software, entertainment, blueprints, knowledge, art, etc...
If ansibles were cheap enough, you could have an interstellar internet to the point where you wouldn't really be able to tell which planet any given person belongs to (at a certain point, ansibles would be the bottleneck because each one would have a bandwidth limit- but if they're cheap enough, they could be used a little bit for intra-planetary comms as well). I have friends in Australia I will probably never meet in person, but that's not really a problem and it won't be in some future with ansibles.
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This isn't exactly an answer to your question, but will help to clarify some things about the current theories about FTL transportation and communication. There are always 2 points of view: the POV of the person or thing (information) accelerating (moving away), and the POV of the person or thing "at rest".
Let's say you hop into a spaceship at the space station and start accelerating away from the station. Relativity states that space and time will appear to distort as you travel, making it appear as though the distance between you and your destination is less than it was before you started traveling. Also, time around you will progress very quickly. The combined effect of these 2 distortions makes it hypothetically possible to travel FTL, but only from your perspective.
Lets look from the other POV. You watch your friend hop into a spaceship and take off. The spaceship accelerates, but that acceleration decreases over time as the speed approaches but never reaches the speed of light. You are dead before your friend reaches the destination 3000 lightyears away, but he's still 25 years old when he gets there (see the [twin paradox](https://en.wikipedia.org/wiki/Twin_paradox)).
Information and light are essentially the same thing, therefore by definition it cannot travel FTL from any external POV. This could be avoided using wormholes, but then both matter and information could travel FTL so the premise of "trade is impossible" is obsolete.
Also, following this new (correct) definition of FTL travel, your shipment of Klavaatu could arrive to their destination halfway across the galaxy without any signs of aging, even though it took 50,000 years to get there. So trade wouldn't necessarily be impossible, but it just wouldn't be the same as it is today.
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Let's assume that civilization is a total loss so after the initial die-off humanity has to rebuild itself from the hunter-gatherer stage. In a particularly harsh environment it may take a few thousand years to stabilize and then progress through the agricultural revolution, early civilization, and into metallurgy. During all this time the ruins of our technology would have been buried, scattered, or exposed to the elements, and all knowledge of how to exploit it lost.
As [this answer](https://worldbuilding.stackexchange.com/a/10143/2241) suggests, a second industrial revolution wouldn't be viable because we've already cleaned out the requisite minerals that can be excavated without advanced technology. I wonder at what point non-renewable resources would be too inaccessible for technology to advance.
Would it even be likely that a successor civilization could develop widespread bronze and iron working? Would there be enough accessible metals and ores for smithing to catch on and lead to advancements? By that time would it be practical to scavenge from our ancient ruins, or would any usable alloys have rusted away? Is there any other path to a new iron age?
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Not as easy as all that.
I disagree with @Catprog and @o.m. - especially given the time-frame.
A *lot* of material is going to get taken out to sea via weathering processes since it's now exposed on surface (and if metal is correlated with humans, most of it is near the sea: In America it's 39% of the population). Most of the ocean stuff will have washed away in hurricanes, global warming, etc, etc. eg: NYC without pumping running ends up underwater / subsiding. Anything that gets dissolved / taken to the sea will precipitate out of solution... onto the ocean floor. You'll then have to wait for it to go through the subduction zone and then recycled up into ores. *That'll take a minute.*
For an example, where is all of the gold, bronze, etc that was mined in ancient times? King Midas was a thing, since he had a mountain of gold ore. It got worn away, since the West used it in coinage.
Or, put it this way, how many garbage dumps from pre-Roman times have metal in them? Or even Roman midden-heaps?
Over thousands of years (or, heck, hundreds) most metals will be scavenged by primitives and used for knives, etc. Worn out and discarded. We don't have any bulk metal from civilizations that're as old as your proposed timeline.
Bronze was *never* easy (nor cheap), and required some world-wide trade routes to get at the tin necessary. It was too expensive for most of the things that needed to get done. How much tin do you expect to find in a garbage heap? How much tin (or bronze) is in your house right now?
Any of the stuff left isn't going to be that pure, most of it will be oxidized, or perhaps reacted with acid rain, or other by-products. You're going to have to figure out how to run smelting to get at pure materials. You can do it with charcoal, but you'll need forests\* (4 to 1) in the right places. You won't be shipping anything by rail, without huge iron deposits to make those rails with - which means any 'garbage mines' will have to be by a river, ocean, or canal, or will have to be located in a forest.
Anything that's corroded, oxidized, or contaminated can be worse than some of the ores we've had. Granted, some of the ores we have had, and used, are exactly that (oxidized metal) - but they're often not the best ones.
All of these would make metals even more expensive than they were historically. Maybe **much** more. Which means you're not going to be doing a ton of experimenting with them. Nor making experimental devices that blow up out of your (equivalent of gold-reserves). The more expensive something is, the less likely you are to experiment with it.
* How're you going to have trees/forests? If you have a catastrophe, you're going to have to wipe out enough humans that they don't burn down all the trees for warmth when the first winter hits that they don't have industrialized society to run their heating for winter. If they haven't already cut them down to cook their food. And they'll need to not be wiping out the remaining trees when they harvest for next winter, and not wiping out *those* remaining trees for next winter... until you can get new growth to mature enough to be reproducing (*and* outpacing new human growth, and survivor's attempts at restarting industrial civilization).
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Metallurgy would re-develop relatively quickly.
After an apocalypse, even if all the useful technology is gone, humanity wouldn't fall back to anything beyond 1700-ish technology. That is because all the very basic inventions - wheels, pulleys, irrigation, the concept of a printing press, even the basics of electricity - are already known and would not be forgotten. The amount of knowledge and basic scientific understanding in the heads of a group of survivors, yes even modern spoiled suburbanites, would surpass any group of scientists from 300 years ago, even if they could not immediately do anything with that knowledge.
People who survive and procreate would raise their children. Those children would speak in a modern, developed language. They'd learn about the past. They'd almost certainly be able to read and write. They would already know that you can melt metal and make useful things out if it. They would already know you can use coal in furnaces to create steel. All they have to do is start trying.
As for the resources themselves, there is no shortage of iron on Earth. Copper might be harder to find, but then the massive quantities we need in the modern world would not be needed by the survivors.
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The iron in a single wrecked/buried/rusted steelworks would last an iron age town for centuries. Combine that with charcoal and you have the starting of metallurgy.
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I'm going to add a bit to user3082's answer...
**Availability**
Old metals in their purified form: This is going to depend heavily on the types of metal, where they are and the conditions in your post-apocalyptic world. We have all kinds of metal that will last for eons if the worst they get exposed to is just the weather. This includes all metals and alloys that are either rather noble (gold, silver, copper) or that create protective layers (aluminum, stainless steel, ...). However, in other conditions they may just as well corrode rather fast (f.e. seawater tends to be pretty corrosive). Iron encased in concrete will also corrode rather slowly (potentially slowly enough to still be mostly there under a layer of rust after 1000 years).
You may also find a lot of metal encased in plastic. Stupid example: bendable plumbing pipes that are made of aluminum that is encased in plastic on the inside and the outside. I assume your best chances are finding it buried somewhere or in a form that isn't otherwise easily exploitable by people just passing by.
Rusted metal: The metals that do rust will basically turn back into their original ores for the most part (that was the stable configuration they were found in, they will revert to it). Noble metals like gold and silver tend to remain pure (as they are found in nature as well, especially gold). The problem you may have is that they all spread and you can only find traces of ore in otherwise useless material.
There is still ore left, but it's going to be more limited than what we got the first try. We've been mining ore for quite a while now and we obviously started with the ores we could process first. There is probably still a lot of aluminum ore left (one of the most abundant elements in the earth's crust), but it's rather hard to refine for a low-tech civilization. Other ores (like iron, copper and tin) are probably going to be more of a problem (except for rather poor ores that can still be found everywhere). Scavenging what's left of them might be by far the easier and more economic option.
**Metal processing technology**
First requirement is heat for melting. This depends a lot on the metal. It can go from temperatures in the range of 400 - 800 celcius for the softer metals (aluminum, copper, ...) to closer to 2000 celcius for iron. So some could be melted using a well made wood oven, others need a little bit more.
Second requirement is purity. Impurities in your starting materials have a lot of impact on the quality of the eventual result. For example steel is just purified iron. You can make do with impure metals to a certain extent (we worked with impure iron for hundreds of years), but it does have an impact. The tribes with purer metal will have superior weapons.
**Post apocalyptic metalworking**
I think their metal working would start again with metals like copper and aluminum. They both have low melting temperatures and tend to not corrode easily. This doesn't mean they will be in pristine conditions. They will probably have lost some material due to local corrosive conditions (see crevice corrosion, it's on wikipedia), but they wouldn't corrode in normal outside conditions.
They would probably be able to scavenge some steel (and iron-alloys) that are not corroded away and use those straight away. For pure steel and iron, this is going to be rather limited. Alloys like stainless steel may stand a better chance (depending on the exact alloy), but they bring other problems such as: different (higher) melting temperature, need for specific ways of processing (you can't just weld stainless steels without messing up their properties).
So as you wish, iron technology would be rather rare. This may cause iron melting to be developed rather slowly or not at all (and steel production would be even more slowly or not at all). This means that the people that manage to scavenge iron or steel and don't fail at reprocessing could have some interesting advantages. Expect that most steel will turn into basic cast iron as they try to melt it (carbon from ash or burning materials will change the composition). The same problem will cause most iron alloys to fail and basically turn into something similar to cast iron.
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Garbage dumps would be a large source of metal. (not just ore but actual metal, rusted perhaps). And probably in higher concentrations then the original mines.
<http://en.wikipedia.org/wiki/Landfill_mining>
<http://www.theguardian.com/business/2010/oct/11/energy-industry-landfill>
And with the thousands of years the toxicity would have leached out and broken down.
For coal it would depend on the Apocalypse. Large scale flooding of the forests is how coal was made originally.
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It would be very difficult for a post-apocalyptic civilization to rediscover metallurgy. As others have stated, the raw materials necessary for industrial scale production of iron (or any other metals) probably wouldn't exist in their world.
At one time in our distant past, there was an abundance of raw materials available. It wouldn't be uncommon to find a large gold nugget, or a diamond lying on the ground.
Now we must go through extraordinary measures to retrieve these resources. The vast majority of what is found today comes from mines deep within the Earth. Some of these mines are thousands of feet deep.
These people may still be able to find commonly elements such as iron in shallow mines. The rarer and more valuable elements may be completely unknown to them. It would be unlikely they would have access to ancient (our) technology. Over the course of a thousand years, the vast majority of our cars, buildings, etc. would decay and be unrecognizable. It only takes a matter of decades for items made of iron or steel to completely rust away if they are left out in the elements.
It is feasible that these people could go for tens of thousands of years and not progress further than being a hunter-gatherer society. It took thousands of years for our own society to prosper, and we had many more advantages.
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In novels (SF and FF) that hint at being earlier in Earth's history, such as *Lord of the Rings* and *The Wheel of Time*, in which period would such a story need to take place to plausibly and realistically be able to play out into our history?
Some examples are *LotR*, *Star Gate*, *Fringe*, *Assassin's Creed*, *The Event*, etc. The plot involves humans (or humanoids that are uncanny to us), elves, aliens etc. that had hyper-advanced (magical or technological) civilizations on Earth long before we were around. But I have yet to find one that goes into (educated) detail as to when and how this was possible without causing huge inconsistencies in a timeline that should end up with present day.
(I understand that many factors go into this such as deep time, geographic details, species evolution continuity/extinction events and archaeological discoveries, but it does seem to me that there should be a time frame (thousands? millions?) where it would be possible to fit in a fictional continuity and still have history play out in the way we know it. If the answer ends up being a discussion instead of a quick response, feel free to PM me)
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While a fictional society with say, tribal elves using bows and arrows could be "mistaken" for humans in the real-world archeological record, a high-tech or very exotic civilization needs to have every trace of it removed. You can do this by:
1. Putting it in the distant past
2. Locating it far away
3. Limit it to a small geographical area
4. Invoking a cataclysmic destruction that wipes out all evidence
Plato's story of Atlantis invokes all four. It existed 9000 years before Plato, it was located somewhere in the uncharted atlantic, on a single island, that sank into the ocean.
To answer your question, the choice of time period in your own story will then depend both on how exotic the forgotten civilization is and to what degree you invoke techniques two, three and four.
The updates to the Atlantis myth also reflects this, by locating it in more and more remote locations [3]. In 1623, only some fifteen years after the Jamestown Colony was founded but with Atlantic crossings to south and central american colonies already routine, Francis Bacon chose to place Atlantis off the west coast of North America. In 1934, when most of the world was well chartered, the italian Julius Evola placed Atlantis on the North Pole [2]. The pole had first been visited only 8 years earlier, by Roald Amundsen in an airship. In the 60's and 70's, when exploration of the sea-floor was well established, Erich Von Däniken and others proposed that Atlantis was instead beneath the ice sheet of Antarctica [1].
[1] <https://en.wikipedia.org/wiki/Location_hypotheses_of_Atlantis#Other_locations>
[2] The american William Fairfield Warren had also proposed the North Pole Atlantis in 1885.
[3] A notable exception is Professor Olaus Rudbeck at Uppsala University, Sweden, who in 1679 proposed that Atlantis was in fact Sweden and that the capital of Atlantis was his own Uppsala. For this he was widely ridiculed.
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The challenge of inserting a high-tech society into an under-documented part our history is getting rid of the artifacts of that society. Fall back ten thousand years and you have a clean slate and almost unlimited editorial freedom to play with. Just be sure to clean up your toys when you are done.
As an example, in one of my stories, I have a space-ready human society buried in the pre-histroy at a depth of about twenty thousand years. As they begin colonizing the moon and mars, they catch the attention of the neighborhood star-spanning empire, which immediately conquers them with nanite disassemblers, stripping every scrap of plastic, concrete and processed metal from the surfaces of all their planets. In the absense of their technical toys and structures, the surviving humans fall back to a pre-bronze age technology level and the rest of the history proceeds as our historians teach. My story opens about a hundred years from now, as, for atleast the second time, we come to the attention of the star-spanning empire.
The believability challenge in hidden history stories is not justifying the existence of prehistoric high-tech. It is justifying our current day ignorance of the glory of our past.
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The main problem with any advanced society is that we have no evidence of it left behind. Even if thousands of years passed with human vanished you would find metals, plastics, bits of railroad, remains of reinforced concrete, etc littering the landscape.
This was handled in the Giant's Trilogy (James P. Hogan) by having the human civilization in question occur on another planet in our solar system.
A war on that planet destroyed it and humans are descended from refugees of that war who crash landed on our planet. (There's more to it than that but I'm avoiding more spoilers than I've already given). The first book in the trilogy is "Inherit the stars" and it's really good.
This nicely explains how we weren't even aware of this prior civilization until when exploring the moon we start finding things they have left behind.
Really we need more details on what you want to be forgotten before we can be more specific though. Is this a few people or an entire culture. Are we talking magic or science, etc.
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It really depends on the area. Such concepts are a kind of "god of the gaps" view of history, so the more unknowns there are about a given culture, the more easily one can get away with inserting material into their history. For most areas, that is probably going to be the rise of the modern civilization that still exists there - like Rome for the West, the Qin dynasty for East Asia, and so on. As soon as a largely common written language comes on the scene, and a cultural continuity is established, a lot more becomes known about civilizations.
However, for some areas, you might have more leeway. Even despite intense archaeological research, we still know very little about most of Mesoamerican history. Places where there was no technologically-advanced civilization before colonization, like the Pacific islands or parts of Africa, could go right up to the modern age.
There isn't really going to be a catch-all answer, since different people are inherently going to find different things believable, and how likely they will accept things they don't find believable depends on how good you're handling the material. I personally find the idea of aliens in Ancient Egypt to be absurd, but even so I liked Star Gate, possibly because it didn't care if you thought it was absurd or not.
Part of it depends on the scale as well. If you insert an entire new civilization (like Atlantis), that is harder to justify than something like saying some random ancient leader was a wizard/alien/etc..
Also remember that the believability is going to depend on what the viewer knows. It would probably be hard to insert aliens into ancient Rome, but it might be easy to do so in India, because most people consuming English-language media are more knowledgeable about Rome than India.
I would warn you, though, that this concept has been largely burnt out, and if you want to go with it, you really should make an effort to be original and believable - and not try to be too serious with it. Think of how much Ancient Aliens has become a massive joke online. Fictional history was really big for a while, especially the 90s, and my impression is people are tired of the concept. There are probably ways to do it, but taking that as a premise definitely is going to add to the difficulty of whatever you are doing.
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You could conceal your society by having it be an actual event that was wiped out. Witch hunts, talking dinosaurs, whatever suits your fancy.
For high technology in the past with plain old humans its probably interesting to note that more advanced technology tends to be really small (nanotech), fragile (biotech), or big (tower of babel). If its small enough you can have radiation ruin it over time until it's unrecognizable. If its fragile you don't have to worry if you place it far enough back in time. And if it's large you need it near a disaster site or else some sort of removal effort by the people, maybe a cultural shift towards being one with nature or something. Meteor impacts, volcanoes, and subduction zones all make good disaster sites. If you place your advanced civilizations collapse at before pangaea (maybe an aquatic tribe?) you could easily have all traces vanish.
Or you can have humans be your disaster. What if your high technology requires everything to be made of gold and silver? Would even a whisper of it have survived into recorded history? I don't think you even need to go that far back for something like that.
For hiding spots that are still viable you have tropical jungles, underground caverns, under the Antarctic ice sheet, in deep sea rifts, and under a desert. You have to be careful with what remains your hiding of course but I can see a solitary lab in the jungle going undiscovered under some tree.
Magical civilizations are easy. They have almost nothing to hide even if artifacts are required and especially if they're not. Why make a shovel when you can wave your arms and be done with it? We easily interpret things as ritualistic currently so you could place those *anywhere* you want on the time-line. The Aztecs could have had super-wizards at one point until the line died out and the priests devolved into mimicking past wizards. Who knows?
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`if %errorlevel% 1 goto TL;DR`
I just want to point out that I heard a story today about an archaeology team who found ruins on Honduras recently.
The ruins were in a place that was so remote, it could only be reached by helicopter. They were also forced to take along some ex-military specialists who had to rope down from their helicopter to cut away brush, thereby clearing a landing space. Also, the animals they encountered near these ruins acted as if they had never come in contact with humans before.
Here's the kicker: the art found in the ruins and the other archaeological data they gleaned did not match any previously known civilisation.
The point is, there are still civilisations whose cultures and existences are completely unknown to us! Generally, these can only now be found in very remote spots, as other answers have suggested, although it is impossible to know what history has been erased during development of land.
Other than housing untold numbers of civilisations, benefits of a remote area include a minimal impact on current history.
`:TL;DR`
As for a specific time period, the ruins seemed to have been between 400 and 800 years old, placing their existence at a time before Europeans really began to explore the globe. So, a good place to start would be somewhere before about 400 years ago, in either the Americas, central-to-northern Asia, Oceania, or any of the many islands in the Pacific.
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If humanity has existed for some 200,000 years, as it currently is believed, then I would look at some of the earliest civilizations we know of, and consider them to be a point in which such stories were already lost. A lot of leeway here, but I am unsure as to whether the time span of 200,000 years accurately reflects anatomical humans, or earlier iterations of our species.
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Modern science and technology would be able to detect if there had been widespread mining and building of all kinds in, I guess, at least the past 1 million years.
You’ll need to explain how the civilization ended, obviously, and what traits of them could still be found today (genetic code, artifacts, fossils) or why none. I can see the following work:
* A society with pre-industrial level **millions of years ago**, but rather small population to explain why we haven’t excavated anything. This could also be extraterrestrial castaway with limited amounts of their original technology, e.g. Battlestar Galactica.
* Extraterrestrial **visitors** with magic-like technology that never got left behind. They could live forth in countless myths, but would have to have been gone when human civilizations in areas the ETs visited had acquired writing. See Stargate.
* **Non-human** intelligent beings, e.g. sapient dinosaurs that utilized only organic materials or underwater creatures. For instance, the Indus valley culture had developed writing, but almost no written evidence remains, because perishable palm leaves were the paper of the day, whereas the clay tablets of Mesopotamia lasted.
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When we try to come up with a plausible 'lost history' situation, we run into a few limitations that are quite hard to work around without essentially falling back on 'a wizard did it'.
First and foremost, we have a fairly solid fossil and genetic record that lets us set an early limit for anatomically modern humans at ~200k years. Even if we take liberty with the current anthropological understanding of human development and history, it's hard to justify intelligent humanoids that would be capable of civilization more than ~1MY in history. Clearly, if we're going fantastical (elves, etc) or way out there (dinosaur cities) this limit is irrelevant but let's treat a million years as the 'cap' for the sake of argument.
Second, while we can find ways to handwave away most traces of civilization (more on that later), we would absolutely know if any previous civilization had discovered nuclear power. Discovering nuclear power creates isotopes and traces that don't naturally exist and couldn't be hidden or wiped away. There are places in our civilization where steel and other materials from the pre-atomic age are used for scientific instruments because they aren't contaminated and don't interfere with experiments. There are other chemical processes that would almost certainly leave detectable traces, but nuclear power is the most obvious one.
It would be quite improbable for a civilization to reach our current level of technology without discovering nuclear power. Not entirely impossible, but quite improbable.
Third, a modern society leaves large-scale traces. Things like cities, roads, railroads, buildings, piers and breakwaters, mines, and countless other artifacts that would be readily obvious - even after tens or hundreds of thousands of years - as remnants of some kind of civilization. A city could maybe be lost to a jungle or cataclysm, but not the number of cities and infrastructure required for a modern society to function. While you can maybe justify an agrarian civilization, even a classical Greek or Roman civilization would leave clearly artificial artifacts for tens or hundreds of thousands of years.
Now, on the other hand we have a big card up our sleeve - ice ages. There have been approximately ten of them in the past million years, and the massive glaciation gives a plausible way for the earth to be scoured clean. Roads and cities? Scraped away and mixed in with or covered in with glacial deposits. Cement would be ground to dust. Objects and buildings would be erased wherever they are covered by glacier.
The biggest problem with ice ages scouring everything clean is that glaciers don't cover the entire earth. The last major glaciation stopped at roughly 40\* N latitude in North America, which leaves everything south of the Ohio River untouched.
Civilization around the tropics could be swallowed up by the jungle or other growth, but that still leaves a wide temperate band. We've also cleared enough jungle - and yes, found some traces of earlier (hundreds / thousands of year old) civilization that have been swallowed up but nothing that would be a shocking technology level.
So basically, it's hard to justify. One possibility in a sci-fi setting would be that we are a lost alien colony / our ancestors were crew of a crashed starship. The colony broke down for whatever reason (plague, bad luck, warfare, etc), and over the course of a few generations basically lost civilization and later regained it. This makes it hard to justify the fossil and genetic record, but it seems like the most plausible way that there could be a high technology society / civilization that existed before modern civilization.
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Practically any time between the 5th and 10th Centuries. The early half of the Middle Ages has very few surviving documents, with most of what survives from this period being visual art and copied religious manuscripts. Things start to pick up a little more in the Gothic period around the 12th Century, then the record becomes fairly complete starting with the Renaissance, but really, depending on the scope and setting of your events, it's not until the turn of the last century that you couldn't really find a place to tell your story where the events wouldn't be widely known before now.
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Imagine a world (or rather a solar system) where in its history there has been a war with emergent AI's
There are very strict laws governing the speed and complexity of computer systems
However because of the very depleted state of raw materials - (imagine 1000's of years, even after AI emergence) - society has been forced to push their technology as far as they dare.
I'm aware that the Apollo missions had a scary low level of tech. However they had a very rigid mission and a very large team only a few (4-5) seconds away as backup...
What level of computational sophistication (and human skills) would be required to navigate without external help, and would also allow for on the fly "mission" planning, at extreme distances such as the ort cloud ?
(No communicating (or scanning/radar) faster than the speed of light!)
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(*Note: I'm assuming low-efficiency, high-thrust engines similar to today's chemical rockets. If you can manage a constant 1G for the entire duration of the trip, or if you're using a high-efficiency, low-thrust system like an ion drive or a solar sail, navigation becomes very different.*)
Navigating within the Oort cloud for short-duration trips (say, less than 1% of an orbital period) is easy: the gravitational influence of *everything* out there is weak, so a first-approximation solution to any navigation problem is "point your nose at the target, then fire the engines" or "point your engines at the target and fire them". You may need a mid-course correction or two, but those will be minor.
For longer travel times (up to a full orbit or so), you're looking at what is effectively a set of simple two-body orbits: the only gravitating body worth worrying about is the Sun, and all orbits can be treated as elliptical. Yes, you've got other influences such as Jupiter or nearby stars, but everything moves slowly that far out, and a course correction every year or two isn't too hard or fuel-intensive.
For multiple-orbit travel times, the system starts verging on the chaotic and you'll want powerful computers to figure the most efficient path, but I doubt multi-thousand-year missions are on the agenda.
Travel in stronger gravitational fields is harder to compute, but generally there's a single dominant body. If you've got time and fuel to spare, you can treat almost any route as an [orbital rendezvous](https://en.wikipedia.org/wiki/Space_rendezvous) and fly it without any computations whatsoever.
In reality, however, the increased efficiency of better trajectories is worth the effort. In a computer-free world, navigation is likely to be done with [slide rules](https://en.wikipedia.org/wiki/Slide_rule#Specialized_calculators), [nomograms](https://en.wikipedia.org/wiki/Nomogram), and tables of standard transfer orbits, all of which can be prepared once and then used for many trips. Gravity assists will be rare, generally used for trips that can be planned well in advance (eg. the initial leg of your Oort cloud mining expedition). Fancy maneuvers like the "spaghetti trajectory" used to put [ISEE](https://en.wikipedia.org/wiki/International_Cometary_Explorer) on a path to encounter Halley's Comet won't be done except for rigidly pre-planned missions.
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Minimum computational power for navigating a solar system is zero (in other words pen and paper).
First, even if the civilization have not discovered a theory of gravity and Newtonian mechanics, it's possible to predict the orbit of planets very accurately due to the orbits being very regular. Kepler did this long before Newton provided us with tools to calculate orbits from first principles. Indeed, Kepler's calculations were one of the foundations that enabled Newton to formulate a theory of gravity.
Yes, calculating it this way would potentially require several years to calculate an orbit. Which would at first glance make it useless for navigation. But you really only need to calculate the motions once and produce a table or chart from which simpler calculations can be carried out to solve navigational problems.
Once you have a theory of gravity you can easily solve two body problems to calculate a planet's orbit around a star then apply it again to calculate your flight path in relation to the planet. Or use the restricted three body problem to solve your flight path in relation to two bodies such as a planet and one of its moons.
Solving n-bodies *is* computationally intensive. However, a 1kHz CPU is more than adequate to run an n-body simulation in almost real-time (remember, real-time is slow, it takes our planet 365 days to make one orbit). My old 20MHz Mac ran a 2D n-body planetary simulator at about 10 million times faster than real time (assuming the animation draws a planet orbiting its sun every one second, then 365 days divided by one second is 30 million).
Once you get closer to a planet or a moon you can revert to 2 body calculations.
See the Wikipedia articles on the calculations I mentioned above for a better idea of the difficulties involved:
<http://en.wikipedia.org/wiki/Gravitational_two-body_problem>
<http://en.wikipedia.org/wiki/N-body_problem>
I've read several old sci-fi stories where planetary navigation was done by the human navigator using pocket calculators. I guess back then people didn't consider letting the computer do all the work. Indeed, computers and AI were often relegated to solving the really difficult problems like figuring out the meaning of life or making the perfect cup of coffee :)
There is however a tradeoff. The simpler your flight path the more likely it is that you'd be using a lot of fuel. Saving fuel requires planning complicated (and slow) flight paths using gravity assists. You can use this fact to give different factions different advantages. The ones with more resources will have less incentive of increasing computing power. The ones with more computing power need more resources etc.
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Actually, if you want to read more about humans solving those problems, Heinlein (and his scientist wife, can't remember if it was the first or the second) both did some navigational problems in order to get one sentence in one of his novels (he had the wife do it separately in order to double-check his work). It wasn't fast, but it also wasn't *years*. You'd probably be able to get it done even for on-the-fly stuff. I think that was in *Expanded Universe*. In any case, he was telling this to someone in like, 1960-1970? And they were like, why didn't you use a calculator. And he was like, this was before those were invented.
Also, for your scenario, you just over-prep the ships. They get more fuel and more power than they need, so that they can deal with mistakes that happen when calculations are off, or when you need to suddenly dodge micrometeorites.
More importantly, you're going to need to use a *lot* more fuel, and a lot more ship (hydroponics, life-support, etc, etc), in order to have the human brains on-board and functioning at all times (ie: 3 shifts a day) - instead of having computers monitor stuff and call alerts / wake up the humans.
Might be better to breed up space-beasts to collect your stuff for you. Or to run your ship's computational needs.
Also, human breeding. You'd breed up mentats or lightning calculators.
AI has been a hard problem to solve. You could probably get by with the computing resources we have now, since we've not managed to get AI even while *trying*. :D
Depends on the type of AI you've got.
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Our current CPU power is still well short of the singularity or even Restricted Intelligence, let alone full AI. So even a cautious civilization is likely to be able to run CPUs at least as powerful as we have today.
Those CPUs are entirely capable of calculating orbital dynamics, navigation, etc.
In order to prevent the emergence of AI then it isn't really the hardware you need to limit, it's the software. A computer can run as fast as you like but if all it's doing is a well defined and structured thing (for example a word processor) then it will never develop intelligence.
What needs to be limited is machine learning, programs that modify themselves, etc.
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To improve performance of computations while preserving ban on AI, you can have [Analog computers](http://en.wikipedia.org/wiki/Analog_computer) capable of performing one function but no other (safe from AI growing too much power). And slide rule (with pen and paper) is pretty efficient for calculations.
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*Note: I haven't included communication with other humans in my answer, I'm assuming the ship being at the Oort cloud cannot communicate with other ships.*
**Context**
It's possible for the human brain to solve these problems quite easily, as can be seen by playing [Kerbal Space Program](https://kerbalspaceprogram.com/ "Kerbal Space Program") and the Apollo moon landing was achieved with roughly the computation power of a calculator.
**Scanning**
The question is, what does the computer **need** to know. Assuming it has a radar that can output 3D vectors of solid objects you then to store these vectors. You need to decide some resolution and range for the radar. The distance to the moon is 384,000km so we'll make sure the range is big enough to encompass that, let's say 400,000km. (I'm making the assumption here that you don't want your radar to be able to track as far as the Oort cloud, you just want to be able to process reactions to collisions.)
We'll want to be able to pick up fairly small objects on this radar and avoid them so we can split that into units, being practical the 67P/Churyumov–Gerasimenko comet [we just landed on](http://ww.bbc.co.uk/news/science-environment-30069244) is about 4km accross, so we'll want to pick up on that. That means at maximum that we have 100,000^3 units of scanning data to store.
Assuming the positions are measured as integers that's 1.2x10^16 bits of data, or 1.5x10^15 bytes (That's 1500 Terrabytes!) if the entire field of view is covered in matter. The ship is probably not going to be surrounded by objects so we can give it some kind of buffer and say that it can store maybe 100 points, which is of course a lot less, about 150 bytes. Which is really easy to handle.
**Control**
That's just for the scanning data. My calculator can only store about 70 numbers which means it probably can't do what you want. Lets assume a minimal computer with 1Kb of RAM which is 1024 bytes. That's a bit more than we need so it leaves us with a healthy 874 bytes to play with.
What do we need to do with this? Here you need to consider the structure of the ship. I'm going to go with the simplest possible configuration (based on Kerbal Space Program missions):
* 1 Reactionary engine (3 degrees of rotation freedom!)
* 1 Thruster (1 degree of forward momentum!)
*[This just includes motion stuff, I'd expect door, lights, air locks, life support etc to all be simply plugged into some power supply and left to run, turned on and off light light switches.]*
We need to be able to control these and make calculations about how to move the ship. So we need to know a few things:
* Velocity (3D vector)
* Acceleration (3D vector)
* Rotation (Probably a Quaternion, 4D Vector)
These need to be pretty damn precise so lets make them big numbers and say that we need 160 bytes for these! So we're left with 714 bytes to play with.
Now we need to do some maths. Assuming the ship knows its own mass it probably only needs to do $F = ma$ and $F = G({m\_1 m\_2}/{r^2})$ a lot to avoid an object. It might also want to then store a few values about its positions after a move its going to make, validate whether or not that leads to crashing into another different object and try again. So we can add another 100 position values or 150 bytes bring us to, 564 bytes left.
These remaining 500ish bytes of RAM must simply contain some basic logic about the process I described above.
1. Look ahead some amount and predict a crash
2. Try a move and see where it takes the ship
3. If that's no good try another maybe in the other direction
4. Try and correct movement towards some target vector if the ship has a destination
All of this can achieved with very little memory.
**Processor**
I don't know a lot about processors, but these calculations use very small volumes of data. My calculator lags when I press the button and we don't want that, so something in the range of 100+Mhz would probably be okay.
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This all assumes that the calculations are this simple, I've literally stripped the system to its bare minimum. You could say that a few Mb of RAM would be enough for a simple purpose computer and a processor that runs at about 1Ghz. This would not be fast by our current day standards as my phone has 1Gb of RAM and 2.4Ghz clock rate for its processor. Adding more processing would allow for better gravitational calculations and collision prediction.
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Since communication is allowed, you don't technically need any computation power on board the vessel, you just do it on the ground.
+1 for the guy saying you can do this on paper. Just to add to that, you might speed some of the math up using a slide rule and an abacus.
Navigation at those gigantic distances would require accurate telescopes and observations for position fixes. Since communication is allowed, then large ground radio transmitters and receivers can be used to provide some navigational data to the vessel, by tracking its position and monitoring doppler changes to the signal. The orbital calculations could be performed by teams of guys with lots of paper on the ground, and the results transmitted up to the vessel as attitude angles and burn times.
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Imagine I'm writing a sci fi thriller novel set in the modern day, on a space station orbiting the Moon. The crews are supposed to deliver supplies to a lunar station on the Moon, they board a shuttle docked on the space station and leaves for the lunar surface.
To nobody surprise, I will introduce an emergency situation that could endanger everyone onboard the shuttle while they are at a certain altitude above the lunar surface. I need the crews to suit up on something quite similar to the one our chinese astronaut wears today but fancier, then they must evacuate as the order to ditch the doomed shuttle is issued. Now I just want those wearing red to K.I.A by being crushed from the falling debris as the shuttle disintegrated mid air and some to simply die from hypoxia due to equipment failure. I am wondering at what range of altitudes from the lunar surface should the remaining crews to begin their skydives from the shuttle?
This Goldilock range is very crucial for my story, one red suit panicked and jumped prematurely and died on the spot as he crash landed while another red suit suffered a third degree burnt since the shuttle suddenly exploded and produce a giant fireball and engulf him. I suppose a fall from height within this Goldilock range would allow my story to continue on, a few broken bones and some internal breeding here and there is okay they just need to hit the ground and not die immediate. No exosuit, no mutant, no nano-biotechnology, no magic, no alien, no gravitational anomaly and no superhero landing.
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The "LD50" for "impact velocity against a hard surface" is around [17 m/s](https://www.offgridweb.com/survival/falling-injuries-fatality-rates/). If we give a small bonus for wearing spacesuits (provide limited armoring) and the fact that the lunar surface may have a little give and dampen the fall, lets bump this up to 20 m/s.
On Earth this is a fall of about 15 meters, which would equate about 120 meters in Lunar gravity.
One complicating factor is that your shuttle presumably isn't stopped in ""midair"" when the people jump out, so you'll need to apply some $\sqrt{a^2+b^2}=c$ to combine the velocity vectors.
This means your final formula is:
$$v\_{impact} = \sqrt{3.25 \* h\_{jump} + v\_{horizontal}^2}$$
where $v\_{impact}$ should be less than 20 m/s, $h\_{jump}$ is the altitude in meters, and $v\_{horizontal}$ is the horizontal speed of the shuttle in m/s.
Should be noted that a LD50 means that 50% of people die because of this, however those that are, eg, crippled for life or wouldn't survive without hospital intervention are counted as survivors.
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There's no atmosphere on the moon, so the shuttle isn't gliding.
If all the shuttle thrusters have failed, it will keep going according to whatever speed vector it had, plus acceleration from gravity.
Anybody jumping from the shuttle will inherit the shuttle's speed vector, plus whatever extra speed they get from jumping. Then they will also accelerate downward according to gravity.
In other words, if the thrusters fail while the shuttle is at lethal speed, then anybody jumping from it will splat. You just get to choose if you splat in your seat or as a free floating spaceman.
To have survivors, the accident should happen when the shuttle is at survivable speed, for example hovering over the landing pad preparing to land. Then it loses thrust. Unfortunately, that leaves a lot to be desired regarding drama and foreshadowing, and the scene will be too short.
So perhaps they get some foreshadowing to make them panic and put on the suits, like a propellant leak inside so they have to vent atmosphere before it goes boom, or the shuttle misbehaving in other ways.
Now they're missing some fuel, and they don't know if they have enough deltaV to stop before hitting the ground. It's still leaking, so if they decelerate now it will just take longer before they get down, so more fuel will leak, which means they're even more screwed. The only option is a last second suicide burn.
At this point Redshirt #1 does an EVA to try to fix the leak and gets flung into space. He will splat quite close to the crash site.
Now they reach the landing site and do the suicide burn. Someone who watched too much [SpaceX landing videos](https://www.youtube.com/watch?v=4cvGGxTsQx0) yells "I know how it ends", jumps off too early, overtakes the decelerating shuttle, and splats right on the landing site.
Meanwhile the shuttle is decelerating, then as it looks like it's gonna make it, it's almost hovering at the altitude mentioned in every other answer... the thrusters puff out. Those who jump off right at this moment should survive, if they jump as hard as they can towards the sides to get far away from the explosion.
Jumping up only means you will fall down from a higher altitude. Jumping down means you gain extra downward speed to break a leg. So really if you have to pick a direction it's gotta be horizontal.
Now of course all the thrusters don't puff out at the same time so the shuttle goes sideways and rotates, and as the pilot frantically tries to save the day one of the thrusters finds some leftover fuel and goes to max, sending it in a spin and away from the lucky guys who jumped at the right moment.
It bumps into a building, then lands on its nose and stays still. At this point the guy who's still strapped in his seat because he'd rather die comfortably says "See? I told you so." Everyone else jumps off. As he unclasps his seat belt, he falls and crashes into the windshield, hitting the cargo hatch release lever. Miraculously, the hatch still works, it opens, bumps against the building, pushes the shuttle and tips it over. It crashes on the ground on top of a fully fueled vehicle, which explodes, blowing up the smartass.
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> It's not the fall that kills you, it's the sudden stop at the end.
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That said, if we look at the [statistics](https://www.safeopedia.com/at-what-height-do-falls-become-deadly/7/7503), we find that free falling from the range between 3 meters (10 feet) and 4.5 meters (15 feet) significantly increases the fatality rate.
Falling from that height on Earth gives an impact velocity between 7.7 m/s and 9.4 m/s. On the Moon, with its reduced gravity, that impact velocity would be achieved when falling from between 18 meters and 27 meters.
Considering that the chances of soft landing of the Moon (splashing in water, impact dampened by vegetation or other obstacles, etc.) are rather slim, and that the crew would be jumping with a non null horizontal speed, which would make the stopping even more energetic, I would trust the Earth statistics to be valid also on the Moon.
More in general, gravity on the Moon is 1/6 than on Earth, so you can take the fall range from Earth and multiply it by 6 to get the equivalent range on the Moon to have the same impact velocity.
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There is no atmosphere. If the shuttle has no thrust, and you jump out of it, the speed you hit the ground will be basically the same regardless of when you jump (or, if you don't jump at all).
The shuttle is trying to land. When in orbit, it is flying around the moon, mostly horizontal to the surface, at a very fast speed. The Lunar Gateway does this somewhat quirky orbit (from the perspective of Earth orbits) that is elongated and not at all circular, as the gravitational attraction of the Earth distorts lunar orbits.
Regardless, your shuttle is landing. We get fictional control over HOW it lands in order to make the story work in a way that makes sense.
I think your best bet is to have the shuttle shed its horizontal velocity first, and land "strait down". This can be described as a matter of near-lunar flight path control: landing shuttles from orbit show up as descending dots, not as lines flying over the surface.
They then fall towards the surface, decelerating to keep velocities reasonable as they go. The lower altitude they thrust the more efficient it is, but also the less safe it is, and if your rocket has constrained thrust rates you might not have time near the surface.
As the shuttle lowers itself, it can have partial engine failure. It no longer has enough thrust to come to a halt before crashing into the ground.
So it could be a matter of working out how much remaining thrust it has, how hard the remaining thrusters can burn, how fast fuel is leaking, and the like to determine the "ideal" time to bail out.
Your space suits may also have small, weak EVA thrusters.
A problem here is that the space shuttle will end up impacting at about the same velocity. And in most impacts, having a shuttle crumple zone around you will increase your chance of survival. For you to impact slower than the shuttle, you need to have more rocket delta-v than the shuttle does when you separate. This is tricky, unless your EVA thrusters are quite strong, or you have something else like that available.
Lunar surface gravity is 1.6 m/s^2 -- and at speeds much over 20 m/s^2 you aren't going to survive. This means you have to bail out under 13 seconds before impact in almost every situation; if you bail out of a stationary object and take more than 13 seconds to hit the ground on the moon, you are really likely going to die.
A final idea would be to take aim for something on the moon that would help you not die. Imagine if there is a plastic membrane surrounding a garden - your plan is to jump, blast a hole in it, then use the expanding air to cushion your fall.
Doing so perfectly would be insanely hard, and missing by a bit would result in you being thrown into orbit (which ... might be better than splatting! You can be rescued from orbit.)
1/3 of an Earth Atmosphere is 30 kPa. If you are hit by 30 kPa for 5 seconds, a 1 m^2 human would be flying at 1 km/s (and have died from the impact). But the point is, there is more than enough oomph in near-earth-atmosphere air to throw a falling astronaut into lunar orbit.
So I'm imagining a precision jump that makes you fly right above a dome, blowing the dome to get a shockwave of air, then using that shockwave of air to knock you back into lunar orbit.
Those that jump early or late ... miss the key moment.
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Your big issue on the Moon is that there is virtually **no atmosphere** to slow you down, so there is basically **no terminal velocity**. The higher you start from, the faster you will get, no limit there.
On Earth a skydiver in belly down position (the slowest possible) will reach a terminal velocity of $55\space m/s$ (about $200\space km/h$) after a few seconds.
On the Moon, **nothing will stop you from accelerating**, and your vertical speed (in $m/s$) when you "land" (crash) will be about $1.79 \times \sqrt{h}$ where $h$ is your initial height in meters, **if** you start with no speed at all.
The lowest orbital altitudes are around $100\space km$, so even if you ship was midway when your protagonists started their fall (and they were magically standing still relative to the Moon when they did), you would still crash at $400\space m/s$, or $1440\space km/h$. Ouch. Even at $10\space km$ that's still $179\space m/s$, over 3 times terminal velocity on Earth.
If we consider that the terminal velocity on Earth is about the maximum one can **possibly** survive (there have been such instances, but usually with a lot of mitigating factors, such as snow, vegetation, etc, none of which exist on the Moon), then the corresponding altitude is less than $1000\space m$.
Given the lack of soft surfaces on the moon (yes, it's covered in dust, but as we saw when missions landed there, you don't sink in it as you would in fresh snow, it's a hard surface), it's probably a lot less, on the order of hundreds or even tens of meters. Basically your spacecraft is just about to land.
To make it survivable from higher altitudes you need something to slow down. Again, since there's virtually no atmosphere, anything which uses drag to slow you down (i.e. a parachute or sail) won't be of any use. Your suits would need to be equipped with some other device which is able to counteract gravity during the whole descent (or alternatively, to slow you down before landing). Exactly what type and size/weight that would mean is probably for another question, but I fear this would largely exceed what you could have in some sort of [MMU](https://en.wikipedia.org/wiki/Manned_Maneuvering_Unit).
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There are so few actual scenarios that would allow anyone to survive as to make this look really quite made up.
Given you are landing on an airless object, you'd want a trajectory with a minimum energy expenditure to get you to zero horizontal and zero vertical velocity at the landing pad. Or as close to zero zero as is reasonable.
There just wouldn't be enough time do do anything like getting in to suits, or even getting to a door to get out in this LD50 window. [remember the max velocity you get LD50 from is about 20m/s]. So your survivability window would begin with your lander stopping all Vel in both directions at 120m and everyone bailing out all at once you fall for about 12 seconds. It ends with when you could get out of the lander with your initial velocity [from the falling, no longer decelerating lander] plus your freefall acceleration rate adding up to 20m/s. So something considerably less than 12 seconds and 120 meters up.
Maybe a better scenario is to have the ship explosion happen, but use automatic escape pods with built in rockets.
Some crew get killed in the explosion, some with damaged pods, some not being able to get to safe landing zones, etc.
I think that is a much less contrived circumstance.
Orbital mechanics is a bitch!
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**EDIT: People are having no fun on a question not tagged [science-based](/questions/tagged/science-based "show questions tagged 'science-based'") or [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'"). The default on this Stack is [science-fiction](/questions/tagged/science-fiction "show questions tagged 'science-fiction'")**
So, let's up the ante. Terminal Velocity on Earth is 53 m/s. That's the speed (give or take, we'll ignore that) that Ms. Vulović achieved on her descent. L.Dutch's worry about vegitation and snow are irrelevant. At that velocity the apparent solidity of both and thickness of either are irrelevant. But, if you wish to insist they are relevant, then so, too, is the astronaut's space suit. Further, while the surface of the moon is nothing at all like a sponge, [it isn't hard as granite, either](https://www.lpi.usra.edu/publications/books/lunar_sourcebook/pdf/Chapter09.pdf).
So, simplifying this and having established that a human can survive a 53 m/s descent, we ask ourselves, at what altitude above the surface of the moon would 53 m/s be achieved? Using a [free fall calculator](https://www.omnicalculator.com/physics/free-fall) we discover that happens at about 870 meters.
Therefore, based on known survivability conditions and actual physics, ignoring both the theortetical value of vegitation and snow vs. space suits, your astronaut's upper limit is 870 meters.
But he/she can still die by tripping on a rock.
**This answer assumes a straight descent**
Since we're getting into specifics... Orbits only happen when things move [and move fast](https://what-if.xkcd.com/58/). The proposed [Lunar Gateway](https://en.wikipedia.org/wiki/Lunar_Gateway) extraterrestrial space station is planned to use a [near-rectilinear halo orbit that also uses an Earth-moon lagrange point](https://en.wikipedia.org/wiki/Lunar_orbit). In other words, the shuttle will be a long way away from that space station or the tangential speed of the astronaut would make the rest of this discussion entirely irrelevant (assuming he/she hit the moon in the first place).
But at 870 meters altitude a shuttle will have lost all but the horizontal approach velocity... but that velocity matters, too. Thanks to air resistance, Ms. Vulović couldn't exceed 53 m/s in any direction. Not so your astronaut.
Speaking generally, the approach velocity of an airplane on Earth must be about 1.3X its stall velocity (the speed at which the plane can't sustain flight). For example, small planes often have a stall velocity of 26 m/s and thus an approach velocity (for landing) of about 34 m/s. That's below the 53 m/s known maximum limit, but thanks to no atmosphere on the moon, the aggragate vector velocity exceeds 53 m/s. *Except...* no air on the moon means no stall velocity. Shuttles will for the sake of efficiency slowly shed tangential velocity to match the surface of the moon and then descend, fighting against gravity, and I've already linked a source that explains the landing velocity of the Apollo missions could have been higher than the 3 m/s they planned on due to the cushion of the lunar surface. (Note that because efficiency demands a gentle transistion from orbital velocity to an approach velocity of 0 m/s there could still be an approach velocity condition that lowers the 870 meter practical limit.) But whether or not you can account for that depends on how you design your shuttles and landing surfaces. They'll have a non-trivial contribution, but for the moment, we must ignore them.
Practical maximum: **870 meters.**
*Party poopers... 61km sounds so much more impressive.*
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**Your biggest problem is "what's fatal?"**
Vesna Vulović holds [the world record](https://en.wikipedia.org/wiki/Vesna_Vulovi%C4%87) for surviving the highest fall without a parachute...
**10.16 *kilometers* (6.31 *miles*).**
Other, not so lucky people die from [tripping on sidewalks](https://nypost.com/2019/10/05/man-died-after-stumble-on-broken-manhattan-sidewalk-lawsuit/).
Therefore, using Ms. Vulović's experience as a worst-case (best-case?) analysis and given Earth's gravitational acceleration of 9.807 m/s2 vs. the moon's 1.625 m/s2 I'd say...
*Anything less than 61 kilometers could be reasonably believed to not be fatal — although the closer you get to 61 km the "luckier" your astronaut would be.*
1. I'm not entirely convinced that a fall from any height to the surface of the moon could be fatal. I'm probably wrong about that, but I seriously doubt the threat.
2. Then there's the issue that while your mass is hitting the moon, you simply don't have the *weight* that you would on Earth. Watch those NASA movies of people bouncing along the lunar surface. The astronaut's muscles would be far more capable of absorbing impact energy on the moon than on Earth.
3. Frankly, how you land is as much or more an issue of survival as how far you fall. Land on your head from almost any height and you're dead. But that begs the question of how much the helmet-to-suit connection can absorb and how much force the suit's shoulder construction can absorb. But, since that's 100% within your control as a worldbuilder, it means so long as the astronaut falls on his/her head, whether or not they die is entirely up to you, the author. But if they don't fall on their head... they probably won't die under any circumstances.
*Whether or not they need serious hospitalization after the fall is quite another matter.*
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[Question]
[
There is the classic trope of a kidnapping victim posing for a photo with today's newspaper to prove they still live, or a time traveller correctly announcing Solar Flares before they happen to prove they have future knowledge. In both cases, these can be used as "Proof that the individual was alive at X date".
However, I have a different problem. I want to be able to prove that my time capsule/ancient dungeon/past time traveler really is from Xty years ago and has not been interfered with at any time between now and then. Short of Carbon Dating, which requires specialist knowledge and equipment beyond the reach of a layman, what can be used as a proof? The best answer will be one an unprepared recipient can verify, even if the original creator needs something special to make the proof.
[Answer]
Probably the most reliable way of dating a time capsule, and one that doesn't require the opener to know any science and but little history, is for the capsule to be *poured into* a concrete building foundation.
Unlike burying it under a cornerstone (as was often done with time capsules, but could potentially be faked by tunneling under the standing building), it's very difficult to convincingly fake a cast-in item in poured concrete -- and a building foundation especially so, since it would be a major repair/rebuild job to replace a section of foundation in order to cast in a time capsule at a later date (not impossible, but a large enough project that the history of a landmark building is very likely to include it).
Of course, this is limited to the period (since the mid 20th century, as I recall) when cast concrete was used for building foundations, and requires "chain of evidence" handling to maintain confidence that *this* time capsule was actually found inside the foundation of *that* building, but it doesn't require any instruments more scientific or difficult to use than a newspaper morgue.
Of course, this could also be applied for a capsule from the 1st century BCE to around 3rd century CE, for Roman concrete...
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1. Make up a message. It doesn't matter what it is, but it does matter that it's a secret.
2. Use a [cryptographic hash function](https://en.wikipedia.org/wiki/Cryptographic_hash_function) to make a hash of the message.
3. Publish the hash somewhere that will have a date associated with it and where someone can find it later. The easiest option would probably be in a newspaper in a classified ad.
4. Put the message in the capsule.
When someone opens the capsule, they can perform the hash operation on the message and compare it with the one in the newspaper.
Of course, this is not something most people can do on the spot, particularly if unprepared. To make it easier on them, you can:
* Include clear instructions in the capsule on how to do it.
* Include a device that can perform the hash operation.
* Tell them exactly where to find the published hash.
The details will vary based largely on the level of technology available at each end of the system. The key components are
* A method of encoding a message that is reproducible given the algorithm and the original message.
* Somewhere to put the hash where people will believe it's from when you say it is.
* A tamper-resistant time capsule.
[Answer]
# Ride the comet [☄️](https://www.youtube.com/watch?v=JJe12o96_AA)
## Preparation
* Find a comet with an elliptical orbit that comes relatively close to Earth every Xty years. If no such comet exists and you have enough resources, launch an [artificial object](https://en.wikipedia.org/wiki/Elon_Musk%27s_Tesla_Roadster) on a similar elliptical orbit.
* (hardest requirement for the prover) Print a message or put the capsule on the comet.
## Verification
* Observe the comet for a period of time to verify its orbit. This proves no one on Earth was tampering with it for Xty years.
* Observe the comet using a powerful telescope to verify the message.
* Launch a mission to recover the capsule (easier if you controlled the orbit to align well with Earth's back then).
* Verify that the comet has no engines, just in case.
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I am writing a story that involves the colonization of an exoplanet with very similar properties to Earth. This exoplanet would be orbiting a red dwarf, but due to certain factors (it's atmosphere and the presence of one or several moons) it is NOT tidally locked. Upon arrival from humans, to their surprise this planet already harbors complex life. It has a large ocean, continents, fauna and flora much like our own earth.
My question is: despite all the similarities, would it be plausible for this planet to be radioactively hostile towards humans? What I mean by this is, despite the similarities, could the fauna and flora have adapted to thrive in an environment which would be ultimately too harsh for our own bodies in the long run?
To provide some more context as to why i'm asking this: The plot i'm working on makes it so that when humans arrive, they can breathe without their suits, and at first it seems like the planet is just like earth, but soon after they realize that prolongued exposure to the radiation within the planet leads to early offset of cancer and thus humans can't really afford to live in this planet as it is without applying some form of alteration to the atmosphere (that's a wholenother subject i'll leave for another post haha), which would lead to harmful consequences towards the native life that has evolved to thrive within this specific environment.
Love this forum, it's been super helpful, to anyone taking time out of their day to answer: Thank you!
[Answer]
**Radiation belts.**
<https://astronomy.com/magazine/ask-astro/2020/02/what-is-the-source-of-jupiters-radiation>
>
> Any charged particles in the space around Jupiter will experience the
> planet’s strong magnetic field and get accelerated to high energies.
> These negatively charged electrons and positively charged ions of
> hydrogen (i.e., protons), oxygen, and sulfur form Jupiter’s radiation
> belts... The dominant particle source, however, is the volcanic moon
> Io, which dumps a ton per second of sulfur dioxide gas into space
> where the molecules are broken up and ionized. These processes around
> the moon drive million-amp currents between Io and Jupiter’s
> ionosphere, where they excite intense aurorae on the planet.
>
>
> The highest fluxes of energetic particles are found closest to the
> planet, where they form a doughnut-shaped belt around the equator
> (which causes radio emission that astronomers have measured from Earth
> since the 1960s)...
>
>
> It is Jupiter’s combination of a strong magnetic field, Io’s
> prodigious source, and the magnetic coupling of charged particles to
> the planet’s rapid (10-hour) spin that drives the intense radiation.
> Earth’s radiation belts (named after James Van Allen, who discovered
> them with the U.S.’s first satellite in 1958) are much weaker.
>
>
>
Your planet has a very strong magnetic field and one of its moons plays the role of Io, dumping particles that are accelerated to high speeds. Fast moving particles are the equivalent of electromagnetic radiation as regards biological damage.
Your people do not realize that these belts exist and dip down to and below the planet surface because the belt is not homogenous - it moves with the moons, with high and low tides. In addition a detection method tuned to short wavelength radiation like Xrays and gamma rays might completely overlook fast moving large ions of sulfur and iron.
As regards the prospect of life not affected by particulate radiation, why not? One could imagine Earth life durable to this sort of thing. A simple method: if radiation makes random changes in a genome you could have multiple copies of the genome and check them against each other frequently, correcting according to consensus for a given gene.
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We have examples of life which has evolved to thrive in hostile environment. [Deinococcus radiodurans](https://en.wikipedia.org/wiki/Deinococcus_radiodurans) is famous for tolerating radiation
>
> Deinococcus radiodurans is an extremophilic bacterium and one of the most radiation-resistant organisms known. It can survive cold, dehydration, vacuum, and acid, and therefore is known as a polyextremophile. It has been listed as the world's toughest known bacterium in The Guinness Book Of World Records.
>
>
> D. radiodurans is capable of withstanding an acute dose of 5,000 grays (Gy), or 500,000 rad, of ionizing radiation with almost no loss of viability, and an acute dose of 15,000 Gy with 37% viability. A dose of 5,000 Gy is estimated to introduce several hundred double-strand breaks (DSBs) into the organism's DNA (~0.005 DSB/Gy/Mbp (haploid genome)). For comparison, a chest X-ray or Apollo mission involves about 1 mGy, 5 Gy can kill a human, 200-800 Gy will kill E. coli, and more than 4,000 Gy will kill the radiation-resistant tardigrade.
>
>
>
It's not far fetched to think that, with suitable environmental pressure, complex life could evolve with a similar resistance. After all complex life has evolved to tolerate oxygen, which is also a nasty environmental factor.
However, regarding your plot, a Geiger counter is sufficient to measure environmental radiation level. It sounds very naive to disembark on a planet without measuring the background radiation.
[Answer]
## Ramsar, Mazandaran
[](https://i.stack.imgur.com/fXdX7.jpg)
is a city in Iran known for levels of background radiation 80 times the acceptable level from artificial sources. There is radium in the ground water and radon gas coming up into the air. Yet there is a mystery because reports keep coming in that the cancer rate is *not* elevated. See [Wikipedia](https://en.wikipedia.org/wiki/Ramsar,_Mazandaran) for some description. A leading explanation is a crack-pot theory\* called "radiation hormesis", essentially that you can get an internal suntan from being in radiation. Note this conflicts violently with [government advice from the U.S.](https://www.dep.pa.gov/Business/RadiationProtection/RadonDivision/Pages/Radon-in-the-home.aspx), though that hardly guarantees it's wrong. A [2019 paper in an Iranian journal](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6709356/) even suggested that the residents should be considered as good Mars colonists. There is [a limited amount of ongoing research](https://pubmed.ncbi.nlm.nih.gov/?term=ramsar+radiation&sort=date) but it doesn't seem very enlightening.
Sometimes - often - biology just digs in like a mule and rejects all entreaties to logic and reason.
* *This term of endearment confused some readers. Please note that "crack-pot theories" turn out to be true more often than expected in biology. Why, just the other day we found out [humans carry an HIV-like polymerase to convert RNA to DNA](https://advances.sciencemag.org/content/7/24/eabf1771), which is to say, Lamarckism may be back on the menu. You never know!*
[Answer]
# Increased Resilience to Errors in Genetic Information
One of the biggest problems caused by radiation to humans is the damage done to our cells' DNA, which lead to [The Hallmarks of Cancer](https://en.wikipedia.org/wiki/The_Hallmarks_of_Cancer). In short, if the right combination of damage occurs to *any* cell's DNA, it will cause that cell to endlessly reproduce, which copies the defective DNA -- the problem is self-compounding.
Our cells have mechanisms to protect against DNA damage via [proofreading and repair](https://www.khanacademy.org/science/high-school-biology/hs-molecular-genetics/hs-discovery-and-structure-of-dna/a/dna-proofreading-and-repair). As the examples on Khan academy show, these repairs largely rely on the fact that each of the two strands in DNA is identical to the other. The Wikipedia article on [DNA Replication](https://en.wikipedia.org/wiki/DNA_replication#DNA_structure) notes:
>
> The pairing of complementary bases in DNA (through hydrogen bonding) means that the information contained within each strand is redundant.
>
>
>
Moreover, each strand is used as a template during DNA replication, as shown here [[1](https://en.wikipedia.org/wiki/DNA_replication#/media/File:DNA_replication_split.svg)]:
This single redundancy is what allows our DNA to be so resilient against damage. Compare the double helix in DNA to the single-stranded RNA used for short-lived information in our cells [[2](https://en.wikipedia.org/wiki/Nucleic_acid#/media/File:Difference_DNA_RNA-EN.svg)]:
Thus, RNA has no redundancy, and is *much* more susceptible to damage. This is why the genetic information of complex organisms in encoded using DNA instead of RNA: the information is far better protected against corruption.
Note how essential [base pairs](https://en.wikipedia.org/wiki/Base_pair) are to both DNA replication and repair processes. Both DNA replication and repair rely entirely on the fact that the only possible DNA [nucleobase](https://en.wikipedia.org/wiki/Nucleobase) pairings are **A-T** and **C-G**.
Now then, you might imagine a structure similar to DNA being used by the biology of your fictional planet. However, instead of using [nucleosides](https://en.wikipedia.org/wiki/Nucleoside) that facilitate base *pairs*, there might be alien nucleosides that can only bond as base *triples*, so instead of **A-T** and **C-G**, you might have **A-B-C** and **X-Y-Z**. This would result in molecule with 3 strands instead of the 2 strands seen in DNA. Thus, instead of only having the *single* redundancy of humans, your lifeforms' genetic information has *dual* redundancy, making it far more resilient against the radiation-induced mutations that cause cancer. This would also render the biological mechanisms that protect your fictional planet's life against radiation incompatible with Earth-based life.
Also note that, because each strand in DNA is a sequence of 4 nucleotides, this is base-4 information storage scheme very similar to the base-2 system of 1's and 0's used in our computers. You could add biological mechanisms that serve as analogs to real-world human-developed [error detection and correction](https://en.wikipedia.org/wiki/Error_detection_and_correction) techniques. Again, such mechanisms would safeguard against the most damaging long-term effects of radiation.
## Side note
As someone involved in space science: radiation is always a major concern, even for robotic missions. I would find it extremely unrealistic for space-faring humans to be oblivious to radiation from the host star of any planet. You might want to give this area some thought.
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You asked specifically about "radioactively hostile" but in case you just meant "very unhealthy in the longer term" - radiation on the surface could be much higher than on Earth (e.g. like Mars) from cosmic sources, either due to the stellar neighborhood or to a weaker magnetic field (again, like Mars). As a total non-expert in this kind of biology I can suppose that the native life has adapted to this, similar to the Earth organisms mentioned in other answers.
Going outside 'radiation', there are any number of trace elements that can be present in soil, and therefore also as dust in the air, that are long-term toxic or carcinogenic for humans e.g. Arsenic (As), cadmium (Cd), chromium (Cr), and nickel (Ni). Asbestos is also a naturally occuring contaminant in various minerals: vermiculite and taconite are well-known examples.
Here's a completely different form of hostility: It seems pretty plausible based on recent research, that life can be constructed from a different set of amino acids than Earth life. And if it can be, the odds are it WILL be on other planets. As a result, if your colonists use native life as food, they will quickly or slowly develop amino-acid deficiencies unless they supplement with the essential Earth amino acids that are missing. I speculate that some non-Earthly aminos might even be actively toxic, but that's just a guess.
One last comment: If you don't want your story to feel like a throwback to the 1950's or 60's, assume that if humans can colonize an extrasolar planet, that their science and technology is MORE advanced than ours, and they will understand physics, chemistry, biology, and medicine better than we do. Unless they've gone through a radical loss of civilization (despite interstellar travel) they will NOT be caught by surprise by any of these environmental problems like radiation, toxic metals, or amino-acid deficits, any more than a team of Navy SEALs would get lost in the desert. Their satellites, or landers, or smart-phones, or body augments, will have told them all about it.
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[
Partly inspired by [this question](https://worldbuilding.stackexchange.com/questions/147113/could-you-live-in-underground-lava-tubes-on-venus/147135?noredirect=1#comment459860_147135)
My Venusians are happy in their cloud top city when a small group somehow (with **lots** of handwaving) crashes to the surface, falls underground, and ends up in a hidden cavern. Our Venusians are in some sort of vehicle that can survive the local conditions, and like caves on earth the conditions in this underground cavern are similar to those above ground. To everyone's surprise they find life living in "pools" in the cavern.
I'm going with pools because (duh!) everyone likes/expects there to be underground lakes/rivers. Also I generally expect liquids to be a requirement for life anyway, as their ability to dissolve other chemicals and act as a medium to speed up chemical reactions is very important for all earth life.
Obviously though these "pools" are not composed of liquid water. Earth gets water lakes, Titan gets methane lakes, but what does Venus get? Given what we know of Venus, are there any plausible candidates for chemicals that would be liquid at VSTP (Venus Standard Temperature and Pressure) and might actually be around in enough quantities to form pools?
There is already a lot of handwaving going on, so if need be I'm happy to loosen the "present in sufficient quantities" requirement.
[Answer]
Venus temperature are enough to melt [lead](https://en.wikipedia.org/wiki/Lead). So, go for it!
>
> Lead is a relatively unreactive post-transition metal. Its weak metallic character is illustrated by its amphoteric nature; lead and lead oxides react with acids and bases, and it tends to form covalent bonds. Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Exceptions are mostly limited to organolead compounds.
>
>
>
Moreover, lead can form chains like carbon:
>
> Lead can form multiply-bonded chains, a property it shares with its lighter homologs in the carbon group. Its capacity to do so is much less because the Pb–Pb bond energy is over three and a half times lower than that of the C–C bond.
>
>
>
[Answer]
# Supercritical carbon dioxide
Once upon a time, [Venus may have had seas of supercritical $\text{CO}\_2$](https://pubs.acs.org/doi/pdf/10.1021/jz5012127) ($\text{scCO}\_2$) thanks to a higher surface temperature (by a few hundred Kelvin) and surface pressures (by a factor of 3 or so). However, now that the atmospheric pressure has dropped to about 9.3 MPa, this is no longer feasible *aboveground*; while there is plenty of $\text{scCO}\_2$ to go around, you're unlikely to find pools of it anymore on the surface.
In subsurface oceans, however, [supercritical $\text{CO}\_2$ could still exist](https://www.mdpi.com/2075-1729/4/3/331/htm), and it would be a decent solvent for some enzymes. Trace amounts of water would be required, but Venus does indeed have such trace amounts in its atmosphere. Under the right conditions, $\text{scCO}\_2$ may fit your requirements.
## The enzymes
[A number of enzymes react well with $\text{scCO}\_2$](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2821001/), including
1. [Lipases](https://en.wikipedia.org/wiki/Lipase), which are involved in the hydrolysis of fats
2. [Phosphatases](https://en.wikipedia.org/wiki/Phosphatase), although these typically function optimally with water as a solvent
3. [Dehydrogenases](https://en.wikipedia.org/wiki/Dehydrogenase), used in certain oxidation reactions; these may involve NAD$^+$ (used in glycolysis) and NADP$^+$
4. [Oxidases](https://en.wikipedia.org/wiki/Oxidase), which are used in oxidation-reduction reactions, such as part of the electron transport chain
5. [Amylases](https://en.wikipedia.org/wiki/Amylase), used to form sugars from starch
We need to be careful, though, as these enzymes can denature and lose their structure at many of the temperatures at which $\text{CO}\_2$ is supercritical. Furthermore, under some conditions, $\text{scCO}\_2$ can inhibit enzyme function, which is why it can be used for sterilization.
## Experimental cases
Apparently (see the previous paper), $\text{scCO}\_2$ has been shown to increase reaction rates in several types of bacteria; for example, it helped *E. coli* and *Saccharomyces cerevisiae* (a yeast) using [$\alpha$-amylase](https://en.wikipedia.org/wiki/Alpha-amylase), the most important amylase in most animals. This occurred at 20 MPa and 308 K.
[Answer]
There is one obvious answer if you discard the "pools" requirement: supercritical carbon dioxide. That is already used as a solvent for organic materials in industrial chemical engineering (e.g., for extracting caffeine from coffee beans). However, at Venus's surface it might be too far towards the gas-like end of the phase to be a really good biosolvent, so...
As a backup, I'd look at molten metallic salts. This class of chemicals has a wide range of melting points, from below STP up past VSTP, so some specific salt or eutectic mixture of salts ought to work. Hal Clement used molten copper chloride as the primary biosolvent for the aliens in *Iceworld* (spoiler: Iceworld is Earth; from the aliens' perspective, our planet is so frigid they could never have imagined life forming here; I mean, sulfur is a friggin' *solid* for gosh sakes!) That has a melting point slightly above VSTP, but that could be remedied by mixing with a second salt to lower the melting point of the mixture.
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[
I was thinking about our history of music, came upon electronic music and started musing about all the possibilities of modulation and such.
I then thought back to a previous question of mine, [*"How might a purely mechanical 'voice' function?"*](https://worldbuilding.stackexchange.com/q/136221/59407), and thought about [Vocoders](https://en.wikipedia.org/wiki/Vocoder#Uses_in_music) and similar synthesizers. Then I noticed that beat-boxers can create similar effects using a solely mechanical device and by it was motivated to write this question.
**Would it be possible to have sounds found in modern electronic music generated mechanically?** I'm looking for the following traits:
* Frequency adjustment
* Volume adjustment
* Synthesis, i.e. combining of multiple waveforms
* Filtering, i.e. volume adjustment according to specific patterns
* Flexible [attack-decay-sustain-release](https://en.wikipedia.org/wiki/Synthesizer#ADSR_envelope)
* [Arpeggiation](https://en.wikipedia.org/wiki/Synthesizer#Arpeggiator)
A MIDI-like system needn't exist, i.e. existing sounds needn't be modulated during performances, they may all have been prepared prior to performance.
[Answer]
TL;DR : These parameters can indeed be controlled mechanically, though not to the extent enabled by today's synthesizers and software.
Pretty much all of the instruments of the traditional orchestra can adjust some or all of these parameters mechanically. They existed well before synthesizers were a thing, though the terminology was different.
Let's take the piano as an example:
Frequency (pitch) is determined by the length and diameter of the string, and controlled by the keys.
As for volume adjustment, the piano can play a range of dynamics, from quiet (pianissimo) to loud (fortissimo). That's actually the killer feature that made piano so popular during the Romantic period. Mechanically, this is caused by hammers hitting the strings with varying strength.
Filtering occurs in conjunction with dynamics. The higher the volume, the brighter the sound (meaning more energy in the high part of the spectrum). The soft pedal can also be used as a "low-pass-ish" filter.
When it comes to synthesis in the mechanical world, the pipe organ can arguably be considered the very first synthesizer in Western music. By combining sets of pipes, it is possible to change the overall sound, much like performing additive synthesis.
Edit: As pointed out in the comments, ADSR envelope can be controlled mechanically to some extent, for example using the sustain pedal of the piano. The envelope of string instruments can be modified by using - or not using - a bow: think of the double bass in classical music (bowed) VS double bass in jazz (fingered).
It is worth noting that, in purely mechanical instruments (and arguably in analog synthesizers), it is almost impossible to adjust one parameter without another varying accordingly, for example frequency and volume, or volume and filtering. Think of an oboe player trying to produce the highest notes of the instrument at low volume, that's near impossible.
As for arpeggiator, you might want to take a look at punched cards and how they were used to generate melodies, typically played by barrel organs. This contributed to the start of electronic music at the beginning of the 20th century.
[Answer]
Not really.
You can reproduce most of the synthesis parts of electronic instruments through mechanical means, but you'd do this mostly individually, whereas synthesizers allow you to change many of the parameters at once. So, a piano gives you some control of the decay and release, and a kick drum lets you modify the attack by changing the beater, and a violin gives you far more control than ADSR. You can also filter sounds by throwing a blanket over the instrument, or closing a door to the room the instrument is in, but the player can't control this on a per-note basis as would be typical in a synth.
So if you want to reproduce the listed effects one at a time, you might find a mechanical method to do so. There are other sounds which are not so easily mechanically reproduced though. Changing the time on a delay, for example, has no mechanical equivalent, unless you move the performer or audience around at incredible speeds and g forces, to use doppler changes...
However, in a more general sense, the questions asks about *typical electronic sounds*. To me, sounds are more than synth parameters, or individual effects. Typical electronic sound to me would also includes aspects introduced during mix time, like **sidechain compression**. This is a very typical electronic sound, and I can't think of a way to reproduce it using mechanical means. Some other examples include **noise gating**, looping samples at non-zero crossing points, multiband compression, **autotune** on vocals, etc. These are typical sounds in electronic music, and are not possible to recreate mechanically, unless you go build a giant mechanical computer with cog wheels to do the maths. I dont think this weas in the spirit of the question :/
[Answer]
You could do this with fluidics. Fluidics allows you to carry out all signal amplification, processing, and even computation with fluid flowing through some funny looking pipes. In fact, you can build devices which operate analogously to electronics using fluidics. The image below describes a fluidic acoustic sound amplification system.
[](https://i.stack.imgur.com/nmbKY.gif)
The device in the middle is one of the most basic devices in fluidics, the fluidic amplifier. The working principle is that a low pressure jet(control jet) of fluid can be used to deflect a high pressure jet(power jet) of fluid between two ports. They have been demonstrated to [work in the KHz](http://acoustics.org/pressroom/httpdocs/132nd/2aaa8.html) [range](https://apps.dtic.mil/dtic/tr/fulltext/u2/a084924.pdf). Operation [above 30 KHz has been suggested](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.578.1490&rep=rep1&type=pdf) by using small amplifiers using light gases such as hydrogen or helium.
We can accomplish volume adjustment with the system above by modulating the supplied pressure to the power jets. Frequency adjustment is also possible too because we can build pressure controlled oscillators. One way this can be done is by routing some of the output flow of our amplifier back to the control ports. In addition there are a number of frequency responsive fluidic elements and circuits. So it should be possible to make a fair amount of sound modulating devices using fluidics.
It shouldn't be too hard to make an attack-decay-sustain-release envelope generator from a couple of amplifiers and passive elements. NASA demonstrated a fluidic stepper motor which was capable of 300 steps per second, which requires applying pressure in a sequence to a series of bellows. The circuit used could be modified to drive a set of adjustable fluidic oscillators rather than bellows to make an arpeggiator.
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The pre-arrangement time would be considerable but you should be able to get good results using something in the vein of the cylinder and comb device found in a common [music box](https://en.wikipedia.org/wiki/Music_box). Similar devices have been used to play elevator music and, through the use of [interference](https://en.wikipedia.org/wiki/Wave_interference), can even be used to recreate complex orchestral pieces to a reasonable degree of facsimile.
[Answer]
If I understand your question correctly; this should be possible in theory; it would just be extremely complicated to design a physical system to replicate it.
Your final paragraph says:
>
> A MIDI-like system needn't exist, i.e. existing sounds needn't be modulated during performances, they may all have been prepared prior to performance.
>
>
>
I am interpreting the situation to be as follows:
1. You are given a sample or waveform of an initial sound which is to be modified.
2. A modification is requested, such as a change in pitch, change in volume, anything which we would typically do with electronics.
3. *Something* mechanical is constructed which can perfectly generate a sound which is the initial waveform with the required modifications.
As far as I'm aware, this is something that is completely possible to accomplish. Basically, if you can do electrical processes to modify the electrical waveform in some desired way, you can do the same thing to a mechanical (acoustic) waveform, through careful design parameters (the same way it is done electrically).
In essence, the main power of [electromechanical analogies](https://en.wikipedia.org/wiki/Mechanical%E2%80%93electrical_analogies) is that you can model electromechanical systems in a mathematical framework. This is essentially what allows us to use electronics to modify electrical signals which eventually are produced as acoustic signals after going through the transducer of the speaker.
Using electromechanical analogy, one could determine the exact input and system parameters required to design a fully mechanical system which, when given the appropriate mechanical input, creates the exact acoustical waveform that you desire. What that system would look like or be made of is far more complex, and outside the scope of what I could guess at.
There are some good tables on [Wikipedia](https://en.wikipedia.org/wiki/Mechanical%E2%80%93electrical_analogies#Classes_of_analogy) which actually show which variables in each system represent the analogous system in other domains. To actually come up with what the physical system would look like, you would require a lot of knowledge about acoustical dynamics; but in essence it would just be replicating the functions of the electrical components with acoustic components.
[Answer]
# Yes, because sound is mechanical
Synthetizers process electric signals to construct electromagnetic waves, which are then sent to a speaker, which will vibrate a membrane to produce the sound.
As long as you can vibrate the speaker just as you would do with the synthetizer, you can mimic its sound.
All computations possible can be done on non-electrical computers (i.e.: a literal cog machine, if you're into that). It may just be that to mimic a microchip mechanically, including its speed, you may need a prohibitively expensive and immense setup. But that does not mean it is impossible.
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[
You may not realise, but animals no more run by instinct than do humans. Like humans, they too have needs. These needs are served by the Animal Court, lowest of the heavenly courts. Formed from the descendants of twelve virtuous animals (the animals of the Chinese zodiac) the Animal Court convenes twice a year and attends to the administration of the animal world, hearing pleas and grievances and communicating them to the higher courts.
Being an official of the Animal Court has its privileges: members of the court are permitted to remove their hides and live as humans while the court is not convened, conducting ourselves as they see fit so long as we do not become derelict in our duties.
However, we animal courtiers are feared by humans; Werewolves, wicked humans so cruel they were demoted into bestial forms for their crimes, also wear the skins of animals to savage their fellow humans. Alas, not all werewolves take the form of wolves. Unfortunately, most humans aren't able to distinguish between us and so both of us are hunted alike.
In times past, the solution was to convene the court far from prying eyes, away from the cities. But now that humanity has industrialised and humans flock to cities like never before, it has become impossible to simply avoid humans as we once did.
But even the cities have animals and the Animal Court is still responsible for them. So the question is: **how can we still hold court without getting caught?**
A few notes:
* Cities have gotten big enough we can't just hold court outside the city; we wouldn't be able to serve all the animals of the city without at least one session in a populated area.
* We no more want to give up our humanity than you would want to give up the wages for your work. In any case humans rarely react well to Tiger.
* There's many courts around the world, not just the one. We can divide our number (or ask for help) to hold sessions in many places, though protocol demands at least one representative from each animal to hold court. We can't be humans for it either. Rules are rules.
* We turn back into animals by putting on our hides, like a coat. Anything inside stays inside, anything outside stays outside. It has to be one way or the other, though - no leaving scraps of cloth sticking out of your belly.
* Besides turning into humans, we're not very magical. Except Dragon. Dragon is very magical, though only in flying and making rain.
* Our hides are ordinary hides when we're not wearing them. We still have to stay reasonably close - same home, say - to them (or we get sick) and while minor damage like needlework isn't a big deal, serious damage can be... serious.
* The city is well into the Industrial age. More humans arrive every day to work in the factories, and we can only expect the city will grow bigger.
* The dragons of the Animal Court range from some metres to tens of metres. Greater dragons exist, but rank too highly to trouble themselves in the lowest courts
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What they need is a variety of forms of private clubs or similars. Even today there are many kinds of organizations which allow their members to convene with considerable levels of privacy:
* Gentlemen's clubs
* Masonic lodges
* YMCA
* The catholic church
* Alcoholics Anonymous
* Herbalife
* New Acropolis
Etc., etc. Notice that at least three of those listed above have existed for centuries. The others could have been created prior to the 20th century, not necessarily on their current form, and it would require little to no suspension of disbelief to do so.
All you need to do is create one or more organization like those ones. If you want animals to be connected on a global level, create a secret organization/multilevel marketing company/religion/charity network that may have representatives across the globe. The major advantage of going global is that you have a way to tend to migratory animals.
If you prefer decentralization, anything that will justify a large group of people gathering behind closed doors will do. AV clubs, furry conventions, warhammer competitions... You name it.
Get a roof on your head and walls around you and you are all set.
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**Sex Club**
In most major cities, there are private clubs with a bouncer. You have to provide a password to get in. These clubs are often closed off areas of bars, where people can come and go with relative anonymity.
You could have a *lot* of fun writing about someone who gets in by accident.
Your protagonist could be a 'normal' human that's just into some weird stuff. He brings his costume, gets all zipped up and ready to go, and that's when things start to get weird.
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**Disused Underground Tunnels.**
Even small cities can have them. The remnants of subways, utility service ways, storm and sanitary sewers, building foundations, and several other things that were created at some time in the city's past, that it wanted to keep hidden and out of the way. They remain, sometimes right next to their current and modern versions, with barely a notice by anyone.
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A dragon invites some family friends to his home for his birthday or to commemorate some event.
Since members of the court spend their time as humans they presumably have income and homes. Since they are not really humans they probably want to stretch out and relax in their natural forms when at home. Since the dragon is the largest and most conspicuous form his home will home best space and privacy.
And inviting some friends to your home is much less conspicuous than anything you arrange elsewhere. Especially if the neighbours are already used to years of seeing the same group of people attending the same event. And **know** what the event is. And that those people really are mostly old friends by having seen them before. Repetition creates familiarity, familiarity creates assumptions, assumptions create mistakes.
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Two large and powerful space empires are currently engaged in a very tense cold war type stand-off with each other. The Colonists are a republic that is concerned with the safety of their home system. The Outsiders are an empire loosely based on the Roman military and government, who want to expand out of their current system and establish a full colony in the Colonist system. For the most part, neither side wants to break the very uneasy peace, but the magnitude of weaponry at each side's disposal means that the first shot of a war could also be the last.
Making matters worse, there is a group of raiders, pirates, outlaws, and slavers that have been united under a single ruler that was once a commander in one of the Outsider empire's fleets. This group, collectively known as the Butchers, is trying its best to cause an all out war by any means necessary. Though the Butchers don't have the technology, resources, or numbers to take on either side directly, they are ruthless and use subterfuge, sabotage, and hit and run tactics.
Arms have been built up on both sides. Ships, guns, ammunition, and manpower have all been acquired in case war does break out. Both sides of the war have similar resources and manpower, with the Colonists having a very slight edge in terms of technology. Both have FTL travel, but special Gateways are the fastest, easiest, safest, and cheapest way to get from system to system. These Gateways cannot be built by either empire, and cannot be removed from their orbits. These two empires have fought before, and small skirmishes happen from time to time, but these are becoming larger and more frequent, and fighting happens in space and on mining platforms on distant asteroids and comets.
So how can I keep this situation from escalating to an all-out war between the Colonists and Outsiders? I've thought of a kind of Dead Man's switch that would cause mutually assured destruction, but considering the technology level of these two empires I don't think that is very practical. So what I'm looking for is, for lack of a better word, some more interesting reasons as to why these two space empires would remain locked in a stalemate.
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**Both sides have competent and insightful leaders who wish to maintain the status quo.**
1. To the pro-industry party currently governing the Colonists, the Outsiders are useful as they are: an enemy at the gates. A party perceived as pro-military and strong on defense will benefit from an external threat. This party favors industry and rich industrialists and the rich have the most to lose with chaos and war and the most to gain by plowing the resources of the state into military expenditures. Also, nothing unites like a common enemy: fear is encouraged among the working underclass so they will set aside their economic and social issues to support the pro-military party. The pro-military party likes things just as they are as regards the Cold War. Cold War means political stability.
2. The Outsiders are fractured into different factions which cooperate well when there are easy military victories and spoils to keep everyone happy. Despite their top-down organization and militaristic society, the Outsider group currently in power is not confident in their ability to defeat the Colonists. They are fairly certain, however, that even one solid defeat at the hands of the Colonists would lead in short order to a Outsider military coup d'etat. This is bad enough for those in power, but some far-sighted individuals among them fear that an unsuccessful move against the Colonists and subsequent fracture of the Outsider power structure will open the door for the Colonists to move on them in their weakened state and eliminate them as a threat.
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Since both empires are extremely dependent upon their gateway networks, any technology which could make gate travel impossible would have devastating effects on both sides.
Each empire has evolve to the point where most of their populated planets are dedicated to a single industrial or agricultural focus. Without the gateways, and the interplanetary commerce which they enable, most of the planets would face starvation and a total collapse of their technological infrastructure should the gateway fail. Billions would die and the survivors would be reduced to pre-technological levels. And the few FTL ships which each empire has kept functional are totally insufficient to make up the difference should the gates go down.
So any weapon, possessed by both sides, which could disrupt or pollute the extra-dimensional space which the gateways connect through, would be a doomsday weapon capable of upholding a tense intergalactic peace.
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Expense exceeds potential gains, militaries are rarely mobilized to simply attack another nation there's usually something more at stake like resources a nation wants or doesn't want others to have access to, or a location of strategic importance which again a nation may want or doesn't want others having access to. These empires are being antagonized and may even be skirmishing but with little to gain and no immediate existential threat they can't justify redirecting resources and manufacturing infrastructure to a full scale war effort, put simply to interstellar empires the resources of one system (let alone one planet) are inconsequential
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Well, if any gate could link to any other gate, it would be possible to send "cruise missiles" thru gates to destroy the gate infrastructure of the core worlds of the enemy by surprise. The Butchers certainly would be willing to do that even if the civilized people were not.
So we can assume that gates are preset point-to-point connections? It should then be possible to fortify gates connecting to the enemy and equip all gates with self-destruct devices as necessary. This would give the defender a huge advantage in logistics which for two nearly equal empires would result in any attack stalling and rapidly and expensively failing.
We could further assume that leaders of both sides are perfectly aware of this because that is what happened with the last (few) war(s). Attacks failed and ridiculous amounts of resources were expended for no gain other than the reduction of border areas to economic backwaters due to irreplaceable gate infrastructure being destroyed. And of course every gate that is destroyed makes the next attack more difficult.
So there would be a fortified buffer zone between the two empires. Some systems might have lost all their gates and have become semi-independent vassal states. Some of the buffer states might be neutral by treaty. So pursuing a war might be very difficult due to the consequences of previous wars.
That is probably the correct direction even if you want the gates to be less limited or non-destructible. Simplest reason for a war not break out is the previous war. It is also the simplest reason for the war to be inevitable. In general, military always acts based on the last war. So just figure some way for the last war to have been bad enough that nobody sane wants a repeat.
This also means that the end of last war should not have left major grudges or unresolved issues compelling to either side. (You can use such grudges and issues to motivate the Butchers, though.)
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If the two sides are two different species and can't live on each other's planets without external life support or thousand years of terraforming, then they might eventually recognise that they are better off if they just start trading the resources they both need.
If they are the same species, then they could seed the surroundings of the gateways with mines that recognise their own ships and blow up when enemy ships come through. Or don't blow up just stick to their hulls and await a command for destruction.
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"...the magnitude of weaponry at each side's disposal means that the first shot of a war could also be the last."
That's your answer right there. Say that each side has the power to destroy an entire planet all at once (Death Star anyone?) then you've reached the level of cold war that we had in reality. No one wanted to be the first to start a nuclear war because it meant mutually assured destruction. That is the definition of cold war.
Keep the skirmishes small and local, and consider that a cold war is the best climate for a spy story.
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What you describe is a [Mexican standoff](https://www.wikiwand.com/en/Mexican_standoff):
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> A Mexican standoff is a confrontation amongst two or more parties in which no strategy exists that allows any party to achieve victory. As a result, all participants need to maintain the strategic tension, which remains unresolved until some outside event makes it possible to resolve it.[...]
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> The key element that makes such situations *Mexican standoffs* is the equality of power exercised among the involved parties. The inability of any particular party to advance its position safely is a condition common among all standoffs; in a "Mexican standoff," however, there is an additional disadvantage: no party has a safe way to *withdraw* from its position, thus making the standoff effectively permanent.
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Your Colonists and Outsiders already have achieved the level of MAD (mutually assured destruction) (based on this:'*the magnitude of weaponry at each side's disposal means that the first shot of a war could also be the last.*'). Neither can advance or safely withdraw. I would not expect further escalation, at least not until the Butchers gather more power. Then they will be able to serve as an external force capable of resolving the existing Mexican standoff.
Proxy wars will be fought. Espionage should flourish. But I seriously doubt that either the Colonists or the Outsiders will risk an open engagement of their troops. If it happens both sides will try to cover it up as fast as possible. The actual Cold War is a very good example of this. Soviet and American troops were frequently present (openly or secretly) in the same war areas but they never officially engaged (or at least there is nothing I know of).
If both the Colonists and the Outsiders can support the stalemate economically, it is quite stable and can last indefinitely.
I would suggest keeping an eye on the Butchers, though. Both empires could and should saw disaccord and disagreement the pirates ranks. The Butchers territory can be used for proxy wars and as a general vent for hawks in both empires. It is also important to prevent the pirates from organising into the third power that can break the existing balance of powers.
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Similar to a [current potential Cold War with China](https://www.nytimes.com/2020/07/22/world/asia/us-china-cold-war.html) and the United States, have both sides depend on each other for some degree of resources and economic support. The Soviet Union had a Marxist socialist command economy unlike the United States' market economy, but both nations could theoretically, and for the most part actually, attack each other in covert operations and have one collapse without affecting the economy of another. However, in our modern world, China and the United States both have market capitalist economies connected to the global economic marketplace with [both economies being linked](https://www.investopedia.com/articles/investing/072915/impact-chinese-economy-us-economy.asp). Companies like [Disney](https://www.usnews.com/news/best-countries/articles/2020-10-06/commentary-mulan-disney-and-the-dilemma-of-doing-business-in-china), the NBA, and American tech companies depend on China for money as well as cheap labor. China owns [movie theaters](https://www.bbc.com/news/business-35723353) and other businesses in the United States that give the country money and resources. A direct war in almost any capacity could devastate the economy of both nations and the rest of the globe even more than the current pandemic. So, have some businesses for The Colonists trade with specific members of the Outsiders and vice-versa. Show how certain industries would collapse if important Colonist businesses pulled out of Outsider territory and how Outsiders get certain beneficial resources from the Colonists. If one were to attack the other, important resources and commerce would be lost. This could lead to both empires collapsing and others taking their place after economic collapse or damaging effects that might affect one empire more than another, shifting the balance of the Cold War. Basically, have the economies be so intertwined that direct conflict would hurt both sides and indirect economic/scientific/political warfare is preferred.
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I am familar with current reactor (experimental) fusion reactor design.
But imagine a fusion reaction happening without a reactor, so there is no reactor hull to shield the sound from an innocent bystander.
It is a small reaction and it is continuus and controlled. (so not all reactive matter is consumed at once)
* Would it make a sound at all?
* If yes, what would that be?
In Sci-Fi shows and the like you will very often here humming and zapping sounds and so on, resembling electricity. Would that be the case?
Please do not consider how realistic such an occurence would be or what happens to the energy 'gained'. I have taken care of that part already :)
*Additional Information in reaction to current answers:*
The device I am talking about is a sort of beam emitter.
Input: Matter in form of small metal spheres.
Output: a "energy beam" of variable width and intensity.
The most plausible reaction to explain that (magical) behaviour is a fusion reaction, at least that's what I am thinking. Am I right?
I know you cannot get that (presumably) if you want to keep things realistic. But thats not what I am aiming for.
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How close have you ever stood to an operational nuclear reactor? I've been within about 20 feet of at least two different ones. It sounds like boring, heavy piles of shielding and maybe you sort of hear the coolant pumps through the hull. If you want to get into the physics, I can do that, but to keep it light hearted, the saying is 'hot rock make boat go'. Fission reactions literally come down to a fancy metal plate that gets hot when you put it close enough to other fancy metal plates at *just exactly* the right geometry.
Fusion doesn't just happen naturally anywhere except in a star, but that's pretty much just because nature didn't find a better way on its own. We have the opportunity to shove hydrogen into a magnetic bottle and pummel it with particle beams until it gives us its lunch money. As long as the hydrogen is close enough to itself when it goes kerflooey, it could keep going kerflooey. There's some really boring math here, but the jist of it is that the reaction has to add enough energy to the system to make it cause another reaction.
This is easier if the reaction is statistically likely to create a neutron, because making atoms beat each other up is *super way easier* than actually going down there to beat them up yourself. But you won't usually get that from slamming two hydrogens into each other, because there isn't a neutron there to spare. It would actually need extra neutrons just to fuse into stable helium.
But that's boring. The point is, this gets nigh impossible if there is anything else there for the neutrons and heliums and whatsits to bounce off of. If you did this in free air just because YOLO, you start losing energy to oxygen going through it's 'goth phase' as a highly unstable neon, and those little bastard nitrogens suck up a bunch of thermal energy and go join the circus with water as nitric acid (as just one possible outcome).
Even if you could contain the radiation and the reaction, you would take steps to optimize this process, which means **the reaction is going to take place in a relative vacuum.** As a result the reaction itself is going to either be soundless, or imperceptible to human hearing.
All that being said, it's probably going to sound like boring piles of shielding and a thrumming, humming magnetic bottle, as well as whatever other technology you have in place around it to make it go kerflooey without boiling people and scorching eyebrows.
**Edit after the edit:** But alas, we WANT to boil people and scorch their eyebrows, and do it in a very specific direction.
I stand by everything I have said thus far. The reactions themselves are going to be completely soundless, assuming that they are *fusion reactions optimized for energy generation.* The hot soup in a pulsing tokamak literally can't touch anything in order to pass on sound, but its magnetic containment can complain very, very loudly.
For a weapon with access to significantly advanced technology or magic, you can actually solve all the problems we have with actual fusion. Assuming you have sufficient energy to pay the cost, you could actually ultra-super-mega heat a completely contained sample of air, squish it to pressures totally obscene, and cut it loose in a fashion that guarantees blazing devastation. The little metal spheres you posit in your question could be bits of lithium, which could work basically the same way - make it stupid hot, squeeze it, point it, pop it.
(Writers note: if you can do this, energy in your world either is, or should be, free, and the difference between 'is' and 'should be' can make for an interesting problem to explore.)
If your question is NOT about the reaction, but about the *beam* emanating from a process like this, there isn't a lot of macro scale difference between this beam and a bolt of lightning except the method of delivery. They are both essentially going to superheat the air they pass through, leaving a relative vacuum in their wake which will lead to a clap. The beam itself could in theory be sustained beyond a pulse-bolt, which I would expect to not sound like much right out of the gate, but I expect when/if it became diffuse and incoherent, it would sound a lot like Satan playing with his blowtorch.
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So you're firing a fusion type reaction in a beam?
Let's ignore the science and use some creative use of the 'known knowns'.
A fusion reaction, such as the ITER Tokamak project, involves isolating a plasma in a magnetic field. Now you've specifically requested you remove the 'housing', which would then remove the magnetic field... which leaves us with plasma.
Plasma itself is just matter in the '4th' state... beyond turning into a 'gas', matter turns into a plasma when it reaches a high enough energy state to shed it's electrons and therefore it ionizes. The device or weapon you need would likely absorb, utilize or otherwise discharge the electrons as 'waste' and would be firing the ionized material as the projectile.
So perhaps you don't really require 'fusion', as such, but a device that perhaps uses fusion to heat other pieces of matter (such as the metal spheres (although it doesn't have to be metal)) to incredibly high temperatures and then shoots them in a particular direction.
Now the biggest problem with plasma is that it will cool down over distances. Which makes me think you'll likely be heating it to *incredibly* high temperatures, perhaps temperatures that are inconceivable in nature (and why not? there is no known 'maximum' temperature.) This would increase the longevity of your ionized plasma beam, allowing it to travel greater distances.
So, now to the crux of your question. What would this sound like?
Well, now we just have to imagine what a burning stream of super-heated matter sounds like as it rips it's way through the atmosphere. I think a great analogy for this in nature is the noise lightning makes just before it 'cracks'... that very first initial opening part of the sound... but drawn out for a long time. When the beam passes by or is switched off, then you would hear the final 'boom' part of the lightning sound, as it cracks and echoes as the air rushes in the fill the hole left behind.
Even more interesting is if you propel the beam at speeds faster than sound, creating sonic booms along it's path :D
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It is hard to answer the question while ignoring the energy gained issue, as some of that gained energy will likely express itself as vibrations which human ears would interpret as sound. Beyond this small portion of the yielded energy which directly becomes sound, most of the rest would interact with surrounding matter in ways that could indirectly create large volumes of additional noise.
If by "I have taken care of that part already", you mean that all of the energy being released by the fusion is being funneled off for some other use, then the noise generated by the reaction would either be a side effect of that funneling or the result of inefficiencies in that funneling process.
Postulations on what those funneling sounds might sound like, would require more information on how the funneling occurs and in what form the energy is funneled away.
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I imagine it'd sound a lot like [the sun](http://www.zdnet.com/article/if-we-could-hear-the-sun-what-would-it-sound-like/) or a star would, but it wouldn't necessarily be extremely loud.
Most sound comes not from the fusion reaction, the fission reactions, burning coal, or whatever the source of energy is, but the equipment that is being used to gather the power being produced. And the sounds those make vary widely depending on application. A coal-fired power plant is going to make a lot of noise because there's no need to spend the extra effort in making it quiet, while a ballistic missile submarine is designed to be almost perfectly silent when it has to, while still generating plenty of power to do its job.
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I would challenge your continuous operation specification. Many things that we humans think of as continuous are in fact just oscillating really really fast. You think that light is "on" when it is actually fluctuating 50-60 times per second.
Your fusion reaction is likely to be operating like the light, fluctuating cyclically very quickly and only appears to be continuous to a human.
When things cycle quickly like this they tend to make a sound, anywhere from a low hum to a very high pitched whine depending on the frequency. These sounds are very commonly associated with electrical equipment which commonly cycle in similar ways. This is what your fusion reaction would sound like.
It is of course entirely possible that this sound would be swamped by the sounds of associated equipment in the area. You couldn't hear the sound of the reaction over the sound of the giant coolant pumps, the sparking of power supplies, or the blast of the ventilation system.
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Probably the same sound as a bare fission reaction would make.
You only hear that which is registered by the temporal lobes in the brain. Usually those are receiving input from the auditory nerves, which are usually only excited when the tympanic membrane is vibrated by sound waves carried across molecules.
So, in the roughest manner, sound is perceived when longitudinal waves of energy travel through media — such as the air, the ground, your body, and the like — and vibrate your eardrums.
Nuclear fusion occurs when the distinct nuclei of two or more atoms approach near enough that it becomes easier for some of their neutrons and protons to fall into mutual nuclear “[orbitals](https://en.wikipedia.org/wiki/Nuclear_shell_model)”. ‘Orbitals’ are, of course, a slightly antiquated name for the set of energy states which are considered to be stable for a certain set of conditions: why electrons stay near an atom, and why the nucleus of that same atom stays intact.
There are a few, and not too many, ways we know this could happen. In particle colliders at comparatively low energies, it is possible to bombard heavy nuclei with $\alpha$ particles, a.k.a. Helium nuclei, so as to synthesize heavier elements. This is how elements like Darmstadtium (a.k.a Ununnilium et al), for example, have been produced.
Lighter, smaller nuclei are less likely to collide at lower energies, so to make them stick you need an adequately dense and energetic — hot — plasma, where many of them are bouncing around.
If the energies of a stellar plasma get too dense, of course, then the nucleus ceases to exist, per se — but that's not relevant. (Neutron star.)
Then, of course, to perform a nuclear fusion at colder energies would require some other means of relaxing the repulsions between the electron shells of atoms — but you didn't ask about that.
When such fusion occurs, the energy is released in several forms:
* One of them is simply an imparting of additional kinetic energy to the resultant nuclei.
* A few neutrinos are emitted. These are largely hypothetical, as detecting them is difficult and indirect, but thus far the predicted characteristics haven't been counterindicated. They don't interact with much.
* $\gamma$ radiation — electromagnetic photons with a very short wavelengths.
* free neutrons, protons, or $\alpha$ particles a.k.a. Helium nuclei.
What manner of sound waves would these produce? Well, I suppose you could always see if the gamma rays, incident on the neurons in the brain or auditory nerve, would excite in a way that would either make them more likely (agonism) or less likely (antagonism) to fire off their neurotransmitters. Gamma radiation has a very small wavelength — well, what we call a wavelength — and isn't likely to interact with matter except on the nuclear scale. Mutogenic damage, sure. Perception of sound? The [Hum](https://en.wikipedia.org/wiki/The_Hum), perhaps?
Not so likely, so far as I would expect.
Most of the sound would come from the resultant heat and thermal activity of the air. In rawest form, it would probably sound like an explosion: a rush of expanding gases.
However, depending on the nature of your containment, you would probably either hear nothing or you'd hear whatever passed through the containment. You don't explain enough about that for me to make accurate assessments.
Now, because you say that the reactions are contained and fed at a controlled rate, the only thing which you haven't adequately explained is the nature of the output beam.
Is it a beam of $\gamma$ radiation? A stream of $\alpha$ particles (Helium-4 nuclei)? Most of the sound from your reactor would probably come from this.
## In summary,
The size of the atomic nucleus with respect to the atom itself is quite remarkable. It has been compared to the distance between the sun and Pluto — i.e. the orbit of Pluto is the atom, and the sun is the nucleus. Tiny.
When nuclear fusion occurs, most of the emitted products are far too small to be sensed directly, more or less, by us. The only thing you could hear would be that which agitated the motion on the atomic or molecular scale.
Ergo: the heat of the fusion.
**Note** that I am ignoring the concommitant operational sounds coming from any equipment which are used nearby, or from the containment of the plasma itself, as your question doesn't ask for such things.
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Let's say that there is a wind going 45 mph and the flight direction of the humanoid creature is in the same direction as the wind. As the flight is in the same direction as the wind, air resistance is minimum, so small it is basically 0. And let's say that this humanoid creature has a wingspan of 5 feet(2 feet per wing + 1 foot for the body) at the arms and a wingspan of 7 feet at the legs(3 feet per leg + 1 foot for the body). And let's say that the number of arm flaps per minute is 120 flaps(so 2 flaps per second) and the number of leg flaps per minute is 60 flaps(so 1 flap per second). And let's assume that it is synchronized so that the 2 arms flap at the same time, the 2 legs flap at the same time and for every 2 arm flaps completed, 1 leg flap is completed. Let's say that every arm flap moves you 3 feet and every leg flap moves you 5 feet in no wind. This makes it easier to calculate the speed.
Mass is going to be important here as is height so lets say those measures are 120 lbs and 5 feet.
Measures:
* Arm length: 2 feet
* Leg length: 3 feet
* Wind speed: 45 mph
* Arm wingspan: 5 feet
* Leg wingspan: 7 feet
* Arm flapping speed: 2 flaps per second
* Leg flapping speed: 1 flap per second
* Height of humanoid: 5 feet
* Mass of humanoid: 120 lbs
Now here are my questions:
1) Can the humanoid creature fly at all assuming his/her arms and legs don't get sore after 1 minute of flapping?
2) If the humanoid creature can fly, how fast can it fly assuming it follows the wind the whole way?
and
3) Is the maximum speed assuming 70 mph wind speed max for no storms anywhere close to the speed of sound at 767 mph?
You notice I am using 100% imperial measurements. That is because my Kepler Bb people use a system very similar to the imperial system but with different numbers of units equaling any given unit. They do however share some base units like inches and seconds and ounces. Once I know the answers in the imperial system, it will be easy for me to convert into the Kepler measurement system(a lot of multiplication and division but that is easy(so like I would convert mph into inches per second and then use the Kepler conversion factors to convert it into Kepler miles per Kepler hour)).
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I'm going to take a stab at a very simple *no*, on the basis that the world's fastest bird can't even hit mach 0.15 in level flight [White-throated needletail - 105mph](https://en.wikipedia.org/wiki/List_of_birds_by_flight_speed).
In a dive you might have a bit more of a chance, birds can fly to nearly 40,000 feet. I'd have to let someone with a much better knowledge of terminal velocities to work out whether supersonic falling would be possible at that altitude. (I suspect not - Joseph Kittinger jumped from over 100,000 feet and didn't break the sound barrier, so if your humanoid has a similar drag co-efficient then he definitely won't).
Your person can definitely only fall though, as with a weight of 120lbs and an effective wingspan of about 10-12 feet he certainly isn't going to fly. Look at the wingspans of large birds - 8-12 feet - and their weight - about 15-25lbs.
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## No, your humanoid won't fly
The lift to weight ratio for your humanoid isn't good enough for the speeds you're talking about. Assuming an earth like atmosphere, your humaniod is about 6 times too heavy to lift itself. Note that the albatross has the widest wingspan of living birds at about 9 feet across but it weighs just 19 pounds. Your humanoid could keep the same wing size but go much faster to generate the required lift but that's problematic because drag [increases quadratically](https://www.grc.nasa.gov/www/k-12/airplane/drageq.html) $v^2$ as velocity increases. Going fast is hard.
For more general information on designing a flying humanoid, NASA has a [great introduction section](https://www.grc.nasa.gov/www/k-12/airplane/short.html) (Specifically the Aircraft Forces section) and that will tell you a lot of what you need to get started.
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Mach number depends on air density which in turn depends on altitude. Concorde could only do Mach 2 at high altitudes.
There are two more serious problems. The first is the reason there are no supersonic propellor-driven aircraft: having a shockwave across the blades severely impairs their operation. The same would apply to flapping, even if you could flap wings at the desired speed there would be a point where the leading edge would be breaking the sound barrier while the rest of the flyer is subsonic. This would cause loss of lift.
The second is that the impact of the air on a supersonic object causes it to heat up. This would compensate for the freezing air at high altitudes, but again would have to be managed in order to avoid cooking the flyer.
(A sub-problem would be energy consumption; I've no easy way of working this out, but supersonic flight is usually achieved only with the aid of afterburners and extremely high fuel consumption. Only some aircraft are capable of "supercruise" without afterburners, and even they need them in order to accelerate to that speed.)
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@pjc50 has the most basic physical constraint detailed very well but I'd like to expand on that answer a little bit.
In short, what you're asking is fundamentally impossible in our world of physics (but there's hope! Read to the end). Let's explore why with some simple examples.
Let's start with a definition. You want to break the sound barrier. The sound barrier is *how fast sound travels through air*. Thus, the direction of air flow is irrelevant, because if the air is moving 70mph west, the sound will have to move an additional 70mph west to compensate. However you would need 70mph (relative to the ground... this is why air speed is measured in knots, which are relative to the wind speed) *less* if you were going the opposite direction. This ends up being irrelevant to your question, however, because even if you're moving east against that current you still need to overcome the force of it. If it weren't for that effect, birds wouldn't be able to hover in the air [like they do](https://www.youtube.com/watch?v=iaI_47gncsw).
Basically, there's a reason we have no supersonic propeller-powered aircraft. It takes epic amounts of compression to pump air backwards fast enough to reach supersonic speeds. A propeller is, simply put, a very efficient wing-flap. Propeller blades are essentially just wings, they carve a bit of air and push it back, using the leverage to push the aircraft forward. The reason they are more efficient than wings is because they have no down-time. A bird wing has a moment of zero-thrust while the wing is returned to its forward position, while a propeller takes advantage of the ability to freely rotate to be constantly pushing on the air.
Yet despite the efficiency of a propeller and its superior efficiency over an animal wing, it still can't break the sound barrier by spinning in open air. It would eventually reach a speed of rotation where it would push more air out of the way than it would effectively push behind it, so you get diminishing returns per your energy investment. Think about splashing your hand in a pool of water, trying to hit a target with it. The harder and faster you splash, the less water you throw in the direction you're trying to splash it. It just spreads out in different directions and becomes less accurate.
That's were [turbofans](https://en.wikipedia.org/wiki/Turbofan) come in. They keep the air from moving out of the way by sucking it into a confined space, allowing the propellers to get better leverage over it. This is a step in the right direction, though I'm not sure whether or not any basic turbofan engines can break the sound barrier.
Jets are basically super-high-performance turbofans, and they definitely have the potential to break the sound barrier, because they tend to dump lots of extra energy into that compressed air (by burning fuel) to make it exit the engine even faster.
So... Unless your creatures have enormous amounts of energy to spend (which you did hand-wave a bit) AND have the ability to internally compress air (IE: not basic animal wings like you're describing), they won't be able to accomplish supersonic speeds. You could possibly build this feature into them, but it will require a bit more hand-waving. See questions [like this](https://worldbuilding.stackexchange.com/questions/15278/sea-creature-moving-via-rotational-motions) for inspiration in that department. That one in particular might have an idea for you: Symbiotic creatures (the "turbofan" part would be a symbiotic creature, not directly part of the main body).
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The argument for superheroes to capture villains alive is that superheroes are already illegally operating as vigilantes and compensating for muggle law enforcement is all they are morally obligated. The burden of dealing with super villains permanently falls squarely on the justice system, not the the superheroes.
The more dangerous super villains are walking, talking [weapons of mass destruction](http://dc.wikia.com/wiki/Joker's_Body_Count) and threats to planetary security. They cannot be rehabilitated nor permanently killed. Keeping them in prisons and asylums that might as well be made of wet tissue paper only puts the public at further risk of mass death and destruction. The only reasonable choice is to permanently seal them inside personalized vaults with the most extreme safeguards to prevent breach (e.g. nuclear warheads), a la the [SCP Foundation](http://www.scp-wiki.net/).
However, a world where governments did this would be a world where conventional superhero plots just can't happen. There needs to be a reasonable justification for why governments and the public at large are perfectly comfortable putting their lives and property at such risk every week.
(I originally asked [another question similar to this one](https://worldbuilding.stackexchange.com/questions/61236/why-do-governments-not-permanently-restrain-super-villains), but failed to take into account the unpopularity of the death penalty and superhero/villain immortality. When I changed to question to account for this, it ended up making the answers into non-sequitur. I decided that this question was sufficiently different that it qualifies as a separate question, but I really didn't want to because I had bad experiences with asking chameleon questions in the past. I leave it to the mods to decide.)
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# They do, or at least they try to.
[](https://i.stack.imgur.com/bI19a.jpg)
Consider Magneto's plastic prison (image above) or the containment box for The Juggernaut when we first meet him in the X-men movies which completely immobilised him.
There are other equivalent cases where the containment is perfectly reasonable customised and secure for the person in question, but lacking against the attentions of, or simply being opened by, another equivalent metahuman. You cannot create a prison that's proof against the attentions of any metahuman, you can only focus it to be able to handle a small group or specific individual.
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One of the tags you have added to the question answers both this and the previous question you asked: **Ethics.**
By not condemning Supervillians to a permanent "death" (actual death or effective by permanent isolation), your society is reaffirming its moral high ground over these despicable people who would put their own goals above that of the greater good.
The thing about Supervillians is that they (are supposed to, at least) represent what humanity would be if we were morally uninhibited and had the power to exploit it. Yes, there are Supervillians out there that are pure evil and everything they do is for the purpose of causing harm, but most of them are trying to achieve an aim which isn't necessarily bad in its own right, just requires doing to morally despicable things in the process. Things like wanting to rule the world (who doesn't want power?).
If you're going to lock someone up, you're basically saying "You are such that you cannot be part of our society". If you lock someone up temporarily, you're also saying "But we concede that some day you might be". If you permanently seal someone away, you're effectively condemning them to death. How many supervillians are actually immortal? How many of those actually immortal supervillians are ever actually caught?
You could also argue that, in an ideal situation, imprisoning someone for a heinous crime is showing mercy - you're giving them an opportunity to change, by being nicer to them than they are to you. Of course, the prison system in most if not all countries has warped beyond recognition of societal rehabilitation; people are more likely to be negatively affected by prison than positively changed, but a theoretical world could have a theoretically functioning prison system.
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# Loki
Norse mythology gives a great example that more or less directly answers this question. For a long time, Loki was the black sheep of the family - a troublemaker, very often on the wrong side of things, causing nearly as much trouble as the good he got up to.
But many of the Norse gods' best feats, and greatest victories, were only possible specifically because Loki was a devious, cunning, backstabbing little trickster. It wasn't until he very clearly crossed the line in a way that couldn't be ignored (killing Baldur) that he finally got treated like the great arch-villain we think of him as.
Your super villains are eccentric, have very strong egos and personalities, and extremely vitriolic and bitter feuds with very important people - the super heroes, entire nations, etc - but are not completely 100% awful.
They will (say) frequently intervene in natural disasters. Sure, they might also take the opportunity to rob a few banks (hey, nobody's perfect), but they will *also* be directly responsible for saving the lives of hundreds of thousands. When the stars are finally right and the Great Old Ones come, they're there trying to stop them, same as all the heroes.
But they're still villains. They (for example) **cannot stand** the heroes, or what they see as the hypocrisy of the world, or whatever, and so they will absolutely not be above (say) attempting to seize control of France when they don't like the outcome of the latest French election. Or even just showing up to blow up the new Stark Tower's opening ceremony, because frack that guy, I never liked him.
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# Corruption
Define "villain".
We usually see heroes and villains with a simple, dualistic view that groups metahumans in one group or another. The "human" in "metahuman" however allows for a lot of grey areas.
During [Marvel's Civil War storyline](https://en.wikipedia.org/wiki/Civil_War_(comics)), Tony Stark (Iron Man), Reed Richards (Mister Fantastic) and Hank Pym (the original Ant Man) got multibillion dollar contracts with the government of the United States (it was also implied that they had it with multiple other countries as well), sometimes using Damage Inc. as a front, to fix property damage that they caused themselves. They also arrested people in their homes without a warrant, imprisoned them without due process - actually without any process at all, and brainwashed and conscripted some of the prisoners into paramilitary service. Some heroes to be imprisoned included Mathew Murdoch (Daredevil), Steve Rogers (Captain America) and Robert Baldwin (Speedball). Stark personally harassed the family of Peter Parker (Spider Man) and nearly had Parker killed on the spot once. Other heroes were murdered by Stark, Richards and Pym's forces.
Stark, Richards and Pym were doing all of this as a witch hunt against any meta human who would not disclose their secret identities to S.H.I.E.L.D. (which had become a *de facto* secret service for the US), or who would shelter or otherwise protect anyone with a secret identity.
So who are the villains, and who are the heroes?
---
Funny thing - a couple months after answering this, I started watching Amazon's *The Boys*. The series itself is the best response to this question. The government would not only grant super villains immunity from the law, it would also spend billions hiring them to do all sorts of jobs.
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If we can put them inside "personalized vaults with the most extreme safeguards to prevent breach" permanently, we can do so temporarily.
We can do so in proportion to their crimes, just as we do for non-powered people. There are two main practical reasons for this.
1. Having two punishments for a crime, one if you happen to have powers, one if you don't, alienates those who have powers by treating something over which they have no control as a reason to treat them worse than those who do not have powers. It encourages them to regard normal humans as their enemies. Even heroic characters may be alienated by this treatment and perhaps insist on creating their own, parallel justice system. (Voluntarily gaining powers and then using them in crime can be treated as an aggravating factor.)
2. If you permanently lock away any supervillain regardless of whether it would be a life sentence for a non-powered person, you encourage supervillains to fight to the death. The smallest chance of freedom is worth the risk because of the severity of the consequence of surrender. This is a problem even now with normally powered criminals. (Alas, some supervillains will fight to the death to avoid three months in jail, just as some normal criminals do. We can only optimize.)
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Answer is the sucide squad. The government keeps them locked in vaults but every now and them the need to pull the out and have work in classified missions for the government. This gives them an opportunity to escape. So every now and then one the prisoners escape while on a mission. Since the mission is classified it's covered up by the government. An official story of there of escape from prison is fabrcated
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**Supervillains level up upon termination.**
Whatever power system your world has that creates supervillains reboots those villains and increases their powers each time they are killed by an enemy. (Suicide doesn't count for some handwave reason.)
Detention facilities that rely on fatal traps therefore only serve the interests of the supervillains in the end. They can just set off the trap, allow themselves to be terminated, and come back even stronger than they were before.
The only way to deal with supervillains is via *superhero clemency* whereby superheroes defeat and capture supervillains but do not kill them. Their detention facilities should be robust enough that escape is difficult, but not so robust that supervillains can easily contrive situations where they can provoke *death by enemy action*.
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Is it possible, the world being as it is for a city to be isolated completely from the world? Assume technological advancements to be the same as they are today.
Would such a scenario be feasible? Can a city be effectively besieged for an indefinite amount of time in such a way that no one can enter or exit?
What effect would this have on the people living in such a city?
Quick Edit: Thank you for all the amazing answers. Just want to clarify, this is being done *to* them, they aren't cooperating
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I would point you to a real world example...North Korea. Currently, the country is isolated from the rest of the world partially due to its own choice and partially due to sanctions placed on it by the outside world. Some things to keep in mind would be the resources that such a city would require to maintain itself. If you are looking at today's world, that is a massive feat to undertake. Today's level of technology was achieved by specialization: many finding that which they excel at and focusing their energies there while trading the products of their labors for their other needs from others who specialized in other ways. If the city in question is to be of an equivalent level of advancement to the rest of the world, then it will have to compete by maintaining all of this specialization within itself. Another question that should be asked is how the city would have managed to have advanced in pace with the rest of the world. Without external factors pushing it (enemies/war), there wouldn't be the motivation to develop fast which should put it far behind most countries.
Food production is also a necessity. Farming requires land. Even the city-states of Ancient Greece had a lot of land to them with which to produce food. This will force your city to be a small landmass to be sustainable. Even if you find a way to produce food inside the city, the city must have developed from a lesser sophisticated one that required the land at one time.
Another question to ask is the amount of time that the people have been isolated. For one, they would have their own culture all their own (or a derivative of a modern day one with whom they split from in the distant past). If they have been isolated for a couple thousand years, they would still be considered human; however, they would have likely developed certain genetic mutations that wouldn't be present in the outside world that could alter their appearance and/augment them differently.
A last note is how aware are the citizens of the outside world? Going back to North Korea as an example, the upper echelon is aware and does participate in the outside world while the masses are sheltered within and controlled. How are citizens who want to expatriate treated/handled? Are they allowed to leave and under what circumstances? Are they imprisoned for their desire to leave? Your form of government will also be key as democracy likely wouldn't maintain secrecy too well with open thought.
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We are still discovering communities in the rainforests, even now.
If you had a willing community (be it due to religion or simply wish to maintain isolation), then there are enough remote places that could "hide" a city if you weren't looking to closely for it. Think of the Arctic/Antarctic, Nevada desert and the rainforests.
I would suggest that beyond a certain population the city would need to be at least partially located underground. This is in part to better hide from Google Maps and in part because remote places are, by their nature, quite inhospitable so would provide shelter from the elements.
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A plague, especially a genetically engineered one. Consider if the common flu was crossed with ebola, in such that the symptoms were merely flu like if you carried a distinctive robust genetic marker, e.g. the ability to metabolize milk, aka lactose intolerance, but ebola-like if you lacked that marker.
A city-state like Singapore might close all borders. With the reduced population they could turn some of the area to farming and subsist in the same location where are larger city used to stand.
Lastly, a cult/superstition situation could arise to perpetuate the seperation and fear of outsiders ("Those filthy milk drinkers!"), long after the initial threat is no longer valid.
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It's possible here are a few ideas
1. War. This city is the capital of an Empire that's been invaded by foreign enemies. For political reasons the enemy can't destroy the city about the city refuses to surrender so the enemy has settled for surrounding the city cutting off all communication to the outside and waiting them out.
2. Religious or/and ideological. The city was founded by a group that wanted to separate themselves from the outside world because of religionsome and/or ideological difference.
3. Some sort of apocalypse, in this scenario the city is a safe haven in a world gone mad. Communications are down so any other a group of survivors in other parts of the world is cut off from the city.
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If the city was specifically built for that purpose or had a few years to prepare its infrastructure for self-sufficiency, that might include setting up a fortress-style walled city, and beds for super-efficient gardening (including choosing only crops that are very well suited for this but also resilient and stable), moving a big part of the living quarters underground so that buildings would not take sunlight away from crops, and choosing carefully how many people (mouths to feed/hands to work) and what kinds of people (genetic diversity, skills/education, social stability) to take in. I see no reason why all that could not be achieved in less than five years, if it was someone's priority, and there are multiple plausible reasons why it could be. The only way a city like that, given sufficiently strong walls, could be overcome is by the besiegers manipulating the weather or blocking out the sun.
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There are possibly two questions here, one about isolation and the other about sieges.
It's possible for a region and its city to be isolated, there are enough islands around the world with once or twice a year ships and no airstrip to say it's entirely possible for a region to be isolated and self sufficient. It's not going to be wealthy or high tech, but it's possible.
In mediaeval times when walled cities were built to be non-porous sieges were practical. Nowadays, a large city is such a vast and porous thing that medieval style sieges are effectively impossible. You could stop the military moving in, you could close all the major routes and blockade the river, but when a city can cover the better part of 1000sqm, you're not going to be able to close every route and still supply your own men. **However, that's always been the game in sieges, can you maintain your own supply lines while cutting off the city.** Maintaining your own lines is much easier these days, cutting off the city is much harder. If you can justify how it's been done then you could probably get away with it in a story, but a modern city is as porous as a very porous thing.
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Depends on what you mean by a city. According to Oxford, a city can be defined as [a large town](https://www.lexico.com/en/definition/city) and according to Encyclopedia Britannica, a city is a "relatively permanent and highly organized centre of population, of greater size or importance than a town or village". Since what is consider a 'city' population can vary between regions and nations, it is hard to say what is considered to be the determining size for a city. Thanks to the laws in Croatia, [the town of Hum with a population of 23](https://timesofindia.indiatimes.com/Which-is-the-smallest-and-largest-city-in-the-world-by-area-and-population/articleshow/2456160.cms#:%7E:text=The%20smallest%20city%20in%20the,Hulun%20Buir%2C%20encompassing%20263%2C953%20km.) is considered a city - the smallest city in the world by population.
Now, if you want to isolate, you could have a city that tries something like the [North Sentinelese](https://thewire.in/rights/american-killed-by-protected-andaman-tribe-on-island-off-limits-to-visitors), have a city on a remote island that is hostile to many people in the outside world. The North Sentinelese are a primitive group, but they live on an island with a population [estimated to be between 80 to 150 people](https://www.forbes.com/sites/kionasmith/2018/11/30/everything-we-know-about-the-isolated-sentinelese-people-of-north-sentinel-island/#4e740f5e35a0). This meets the population criteria of certain places, even if it doesn't meet the technology requirement. Now, the North Sentinelese are able to survive on the island meaning they are self-sustaining, able to live on just what the island provides. Being self-sustaining is important for your city being isolated - it will have to be able to survive with little to no assistance from the outside world. So is the isolation of being on an island, with the amount of water between the city and another human settlement being a great reason for people to stay and no one to get in or out.
Now, while they can have technology, it would be hard for them to have modern technology if they are truly, completely isolated from everyone else. Even [North Korea depends on handouts from China to get the technology it has.](https://www.cfr.org/backgrounder/china-north-korea-relationship) Without modern technology, the 'city' in question could be built by more primitive means similar to the [Mound Cultures in North America.](https://en.wikipedia.org/wiki/Mound_Builders)
[](https://i.stack.imgur.com/gcq12.png)
Using sculpted rocks and soil [to make earthworks](https://en.wikipedia.org/wiki/Earthworks_(archaeology)), platform mounds in the form of [small 4-sided truncated pyramids](https://en.wikipedia.org/wiki/Platform_mound), homes, and buildings could be created with primitive tools or with whatever modern hardware tools they can get their hands on. With this, you could form a small city isolated from the rest of the world. You can have the city be simply far away enough that most people would rarely want to visit it or make the people so distrustful of the outside world that they will use weapons to attack those they don't like and/or potentially capture anyone who arrives to the island city, forcing them to remain a resident of the city. In my opinion, the later would make it easier for the city to remain isolation since the people would simply be too dangerous for anyone who wasn't insane to want to go to. This will probably make the inhabitants xenophobic or distrustful of outsiders. The only outsiders that might be trusted might be those who are captured and indoctrinated.
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Let's face it: You are *The ultimate God*
You created the universe, including its physical laws. You created the stars and alligned them in specific order. You created the solar system where the planets are in order as you wish.
You brought life to one (or more) planet(s) in that solar system and did fiddle with evolution for so long it produced intelligent life.
Maybe you even created other Gods and Goddesses for that intelligent species to believe in. Or you let them all be just atheists. But there is one ultimate truth: In Worldbuilding, you are the ultimate God.
Well, at least in meaning: The one who created it all, the one who knows everything about the universe and the one who has ultimate power about that universe.
In my own case, I am playing with the idea of admitting the idea by having only one God in my world. Myselves.
But the thing is, I am benevolent creator. I would like people to have the right to completely disbilieve into me and reject the idea of ultimate creator of All.
On the other hand, I would like to keep believers happy and give them signs that I exist (last time I checked, I did exist).
How can I achieve this task?
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**Note: Many theologians, priests, rabbis, imams, and believers in God can argue that your situation mirrors life right now. I feel the Worldbuilding Stack Exchange is not the place for this religious discussion. This answer will attempt to answer your question and nothing more; rephrasing this question and posting on Mi Yodeya, Christianity, or Islam SE may yield more insight into this.**
It seems you have several attributes for your deity that you want to enforce. Among which:
* Freedom to choose and of belief is granted to intelligent beings
* Allow for reasonable deniability of the creator's existence
(I should mention that the groups mentioned in the starting note may say things about *why* it is this way, but that's not here nor there for the scope of this answer.)
This is actually easy; this deity ought to give believers miracles which is in line with their faith and that god's will. However:
* These "miracles" need not be supernatural occurrences, but unexpected or direly needed by your believers.
* To retain reasonable deniability, not *everything* should go their way. That is, the more subject believers are to forces and events that occur to everyone, the better.
The key here is that the miracles in question can be explained by "scientific" or "rational" thought. If a person can just as easily look at isolated incidents and say "that was chance" or "it just happened to be that way" as say "that was my god," then people can argue for and against the existence of that god. This can result in the same problem posed by the [Bielefeld Conspiracy](https://youtu.be/XvHcZciihJw), except it's a deity and not a town in Germany; how do you prove that something exists without witnessing it?
**What About Science?**
If this god wants to avoid being exposed by scientific inquiry, you simply need to avoid repeatable responses and bring your miracles about by mundane, natural-law abiding means. My wife is a grade school science teacher, and the public-school approved curriculum teaches that [things which cannot be repeated are not fit for scientific inquiry.](https://en.wikipedia.org/wiki/Reproducibility) (As another side note; lack of repeatability may be why psychologists have [such trouble replicating results](http://www.sciencemag.org/content/349/6251/aac4716).)
**Reliance On Deniability**
Of course, you shouldn't ever discount people's ability to deny. Some people just don't seem to accept some things even though it stares them in the face. People can by annoyingly or unreasonably skeptical, especially when suffering an [existential crisis](https://en.wikipedia.org/wiki/Existential_crisis). After all, if you're unsure if you exist, how can you determine if something else does?
Also, remember the Bielefeld Conspiracy! Non-believers can engage in many of the same type of arguments for the non-existence of deity as well as Bielefeld. Maybe all the believers are in on some big trick against nonbelievers? Perhaps the miracles never happened! Pictures and other evidence can be falsified. The list goes on. (Also consider [Clark's third law](https://en.wikipedia.org/wiki/Clarke%27s_three_laws): "Sufficiently advanced technology is indistinguishable from magic." Maybe the believers or other miracle-workers used technology!)
**In Conclusion**
A deity must not do much to leave room for doubt; simply giving free will to its creations, working within natural law, and not publicly revealing itself may be enough.
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I'm going to take a page from D&D here. (Specifically, the Pathfinder Golarion setting, although this may have been inherited from previous settings.)
In a world where gods (or a God) *incontrovertibly* exist, denying their existence is equivalent to denying that the sun comes up in the east: You can claim it, and totally believe it, but you're objectively wrong. In the D&D settings, there's all kinds of proof that gods exist - clerics draw their power from them, divine servants show up all over, and even the gods themselves might be encountered in disguise.
Instead, in a setting like that, an [athiest](http://pathfinderwiki.com/wiki/Atheism) believes that the "gods" **aren't actually divine**. They're just beings with powers far beyond those of ordinary mortals.
>
> Rather than outright disbelieving in gods whose existence is a matter of hard fact, atheists in Golarion instead deny that the gods are truly divine and thus not deserving of worship or blind faith. Thus, atheists may be classed as dystheists or misotheists.
>
>
>
The same can be applied to your world. You clearly exist. Not believing that you exist is absurd. But believing that you're some kind of superpowerful alien, or time traveller, or hyper-evolved being, or other way-beyond-human-understanding creature is perfectly valid. After all, while you can prove you exist, you *can't* prove that you created everything. Nor can you prove that you're omnipotent or omniscient. All you can prove is that you're more powerful and more knowing than they are.
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Well, just as it's impossible to prove there is no God, it's also impossible to prove there *is* a God!
How does God prove He's God? He could appear in the sky as a giant figure and speak to us, predict the future, tell each of us our own private secrets we've never told anyone, turn water into wine, and all the rest of the magic tricks we associate with God, turn the earth into 7 billion pieces and send us all off into space on our private rocks in different directions and join us together again and have us survive the experience to tell each other about it.
But all that could be achieved by someone powerful enough to fake it! In other words, someone with enough power over the human mind, who could cause vivid hallucinations and read our thoughts (or even just make us think they've read our thoughts like the "link to `file:///C:/` " trick). Any power beyond the ability to do that is impossible for a human to observe.
Atheists know this, so they simply say that there's a trickster (perhaps alien, perhaps a government conspiracy, etc. ) out there doing this to us to make us think there's a God.
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I agree with Pipper's answer, but would like to add/emphasize:
**Perform miracles that leave no evidence, but rarely and only in front of believers.** If you keep the effect localized, and leave no scientific proof (and actually proving things to scientists requires extremely solid evidence) then you can cure cancer, raise the dead, smite evildoers, provide a variety of blessings, etc. Just erase the video and make the photos all come out blurry, so to speak. Disbelief is very resilient. If a skeptic meets someone who looks like someone they thought was dead, they will not believe it's a miracle but a cruel hoax or merely an extremely similar looking person, as an example.
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This is perhaps less of an answer, and more, some thoughts to consider when attempting as you propose.
The main difference between you, the World Builder, and any traditional idea of a god is the reason you are making the world and its peoples.
A deity in your world would likely have in-world reasons to do what they are doing. You can write those in however you like, be they altruistic, malevolent, or benign.
But you, the World Builder, despite how you might craft internal reasons for making the world and wanting to make people happy, you are from beyond that world. You are from a world in which you have your own mortal trials and issues. You are likely writing their world to be something enjoyable to read, which means intentionally creating conflicts that the people in that world will not enjoy. You are likely writing their world to appease some internal desires and fears of your own life.
Furthermore, you do not know everything in their world like one of their deities supposedly would, you only know of it that which you have thus far created (and even then, you probably should check your notes from time to time to avoid retcon). You do not know a character's thoughts, you create their thoughts.
Every character is, to some significant degree, an avatar of the World Builder. Even the atheists are the World Builder themselves, not believing in you because you decided they shouldn't.
[Answer]
You are the creator, not only of the world, but also of the people in it. So instill within them, a healthy dose of self-serving hypocracy. (very much like we have in this real world).
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A person of faith may very well be skeptical and convinced that this entity is a fraud (man-made) if it were to present itself even in an obvious manner, and an atheist may very well be convinced rather easily if it were to present sufficient evidence that was observable by the atheist.
You can't really ensure that this can't happen, since various people have different thresholds for sufficient evidence, different levels of bias, and different personalities.
However, you're God. You can have a bi-directional dialogue with religious people and make it so **only religious people can see or hear you.** Optionally, you can make it so when they're communicating with you, no one else can witness that communication. You could even make it so your miracles, words, and actions differ *based on the religion of the witness.*
Such an illusion was performed in the book/film *Left Behind* (albeit by the Antichrist) when he1
**Spoiler**
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> Executes two men, but everyone except for the Christian in the room sees that one of the men shoots the other man and then himself, an illusion by the Antichrist.
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Conceivably, if it's within the scope of a supernatural power to do this, it's a good way of pleasing all the religious people of the world but at the same time giving freedom to disbelieve to the atheist. *Doxastic involuntarism* (whether involuntarism or voluntarism is the way of the world is outside of the scope of this SE) insists that we not give evidence to the atheist.
Since all observable phenomena would be impossible to record, there would be no observation to make therefore it would be outside of the scientific method.
With such a powerful tool of controlled censorship, as God you have a lot more leeway and time to convince your believers with whatever signs they're looking for, based on their individual desires to see it. You can do this for atheists, as well, if they're looking for you.
1 The assumption here is that if it's within the abilities of the bad guy, it's within the abilities of the good guy.
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**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.
The idea of uploading one's personality and consciousness to a computer is a semi-common science fiction trope. It has been suggested as a way to essential immortality.
In a story I'm working on, an entire society has transferred itself from brains to computers. They're on a spaceship, heading to a new world, fleeing from an apocalypse on their home planet. Putting themselves on computers is much more efficient than the alternative.
Can they upload their consciousness to computers, keep the whole thing running smoothly, *and* hold them in a state such that they might be transferable to organic bodies at a later state (e.g. upon finding a habitable planet)?
Some specifics:
* The society is composed of about 3 million people
* The spaceship is roughly the size of a Super Star Destroyer (from *Star Wars*)
* The journey will take many, many years - quite possibly several centuries
* The technology level is roughly within 50 or so years of today's
* All answers must be based in [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'")
[Answer]
**It depends what you mean by 'conciousness.'**
Unfortunately, we aren't really sure what exactly consciousness is, or how it can be defined.
One one hand, with sufficient advances in technology, it may be possible to create a computer that can act exactly like a human, and to map a human's brain. If we can do this, we could take a crew of humans and map their brains to a computer. If consciousness is an emergent phenomenon based on the structure and activity of though, then this is uploading consciousness. Assuming that we get the process right, the computer would, at the very least, view itself as being conscious, and being an uploaded version of the consciousness of the uploadee.
Assuming that we can 3D-print a brain, which seems to be the logical endpoint of current research in [printing tissues and organs,](http://www.nature.com/nbt/journal/v32/n8/full/nbt.2958.html) we could similarly print a stored copy of the uploadee into a new brain at the destination.
Of course, a philosopher may well claim that we've merely created a copy of the consciousness or mind in question. A priest of many religions would certainly claim as such. If we can scan a brain in a non-terminal manner, it may well be that the person being uploaded will still exist in a fleshy physical body, which can point to the computer and say, "That's not my counsiousness." And they may be right, since we don't know what consciousness is.
For the purposes of leaving a planet and re-establishing the race on a different planet on the other side of a multi-century journey, a more pertinent question may be "does it matter"? Regardless of how we go about uploading a consciousness, and regardless of whether or not it truly represents the copied being, the minds we are storing in the space ship are *functionally the same.* They have the same memories and can do the same things as the original, can be printed back into a physical body at the end of the journey.
Technologically, of course, being able to scan and copy a brain, as well as being able to create a computer than can function in the same manner as a brain is a stretch for '50 years in the future'.
Then again, so is creating a [several kilometer long spaceship](http://starwars.wikia.com/wiki/Super-class_Star_Destroyer) capable of interstellar flight. If your heroes have accomplished that, I suspect they have the resources and capabilities necessary for copying a brain.
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It depends greatly on philosophy.
I will consider only the viewpoint of structural physicalism, not any dualistic or idealistic answers. The rationale for this is simple: if there is a metaphysical mind, the phrasing of your question makes no sense. If there is a metaphysical mind associated with consciousness, we wouldn't be using the hard-science tag now, would we!
The fundamental challenge for such a transfer is that the brain is a living organ. As such, it doesn't stop moving nor growing, mostly through the creation and destruction of synapses, and the electrical activity within the brain. The brain is not "quiescent," which is the technical term in simulated automata for a structure which holds still. Thus, while you are mapping the brain, it is changing. You would likely end up with tearing like effects like those seen in [automated panorama stitching](http://cdn.osxdaily.com/wp-content/uploads/2012/09/panorama-iphone-5-sample.jpg). Sometimes the stitching works [acceptably](http://whyrul.com/wp-content/uploads/2013/11/panorama-fail-18.jpg). Other times the results are, well, [disconcerting](https://s-media-cache-ak0.pinimg.com/736x/09/f7/7a/09f77ae91ba1ab8dc7b4f4349aa5cd08.jpg). This issue would be a major challenge for 3d printing a brain. While other organs are more forgiving with their internal structure, we are rather dependent on the structure of the brain to be "right."
There may be solutions involving extremely low temperatures. If you can induce brain death (no electronic activity), chill the brain down to very low temperatures (to restrict synaptic growth), and sample it, you could reverse the process to print the brain. However, the psychological effects of being rendered brain dead are hard to grapple with.
I would consider a different option, which I would call "budding." If you believe a computer is capable of holding onto a human consciousness, then you believe it has the raw building blocks needed to form something human-like in hardware/software. Consider a case where you create a region of a computer for "use" by a human. Within this region is the building blocks for whatever soul is believed in. The human is then encouraged to build this empty soul into a helpful conscious entity.
This initial phase gives an opportunity to make an entity which is reasonably relatable to by the individual. Eventually it should act like an AI. Now, one opens up the AI to directly influence the world (such as giving it access to the Internet). Very soon, you end up with a relationship that should look similar to a working dog, except with a human-grade intelligence within the computer rather than a dog-like one.
With enough training, a human could be trained to treat the human body and the AI mind as part of one entity, just as those with prosthetics learn to treat the prosthetic as part of their own self. Now half of the combined mind can be put in a computer, simply by breaking the link. However, we want more than that, so lets train the computer to become more and more like the human, until the human can no longer distinguish the difference between the human mind and the AI mind.
At this point, we call for "divorce." This human/computer entity agrees that it will undergo a divorce process where the link will be servered, and whatever stays on the human side will be human. Whatever stays on the computer side will be computer.
You now have a cloning problem. You have two individuals that lay claim to the "consciousness" that was the human/computer. Hopefully there was an agreement ahead of time... maybe Bob becomes BobH and BobC, just to avoid ambiguity. Get all of the legalese in place.
Now you have two entities which both feel they are the natural consciousness of Bob, one of them in a computer that you can send far away.
At the destination, the process can be reversed, generating an organic body which is the extension of BobC. At some point this computer/human body also goes through a divorce, creating BobCH and BobCC. BobCH is in an organic body, and believes it is the naturally following conciousness of BobC, which believes it is the naturally following conciousness of Bob.
Now Bob and BobCH are probably different in many ways. Anyone who one would probably instantly realize that the other is not the same. However, given your story has Bob dying in an apocalypse, there is nothing to compare BobCH against. BobCH claims to be the conciousness of Bob, and there is no evidence to challenge this.
In fact, if BobCC is willing to drop the claim to the conciousness of Bob (either as an understanding of the purpose of computer encoding a human in the first place, or through forcefully erasing BobCC), BobCH can even elect to drop the clarifiers, and assume the name Bob. Nobody would be the wiser.
[Answer]
I can't do the hard-science for your other two questions, so I'll try to just focus on this one.
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> keep the whole thing running smoothly
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**Note: I've made a ton of estimates and assumptions in this answer.** There are obviously many different ways to tackle this problem, and this is only one. There are also many, many other considerations to make in regards to the scenario, but I have indiscriminately hand-waved them away for now.
First of all, let's try to figure out how much storage space you'll need to hold your civilization. [Estimates for how much a human brain can hold](http://www.slate.com/articles/health_and_science/explainer/2012/04/north_korea_s_2_mb_of_knowledge_taunt_how_many_megabytes_does_the_human_brain_hold_.html) vary from 1 terabyte to 2.5 petabytes. Let's just take the high end of that estimate and work with that.
You're going to want some kind of redundancy as well. There are [different strategies](https://www.digitalocean.com/community/tutorials/how-to-choose-a-redundancy-plan-to-ensure-high-availability) for redundancy, especially considering these are *people* we're talking about, but for simplicity, let's go with a [RAID 10](http://www.thegeekstuff.com/2010/08/raid-levels-tutorial/) approach.
$$
2.5\ petabytes \* 4\ drives \* 3\ 000\ 000\ brains = 30\ zettabytes
$$
Now let's consider what medium of cold storage to use. Unless you specify otherwise, there should be no reason why these brains need to be conscious during the trip. From the passenger's perspective, the passage of time should be imperceptible from the time their consciousness is loaded into storage, to the time their new bodies are created. So let's use [magnetic tape](http://www.forbes.com/sites/tomcoughlin/2014/06/29/keeping-data-for-a-long-time/) for our long-term storage. In my opinion, there really is no better way to keep things running smoothly for your scenario.
The latest generation of [LTO Ultrium](https://en.wikipedia.org/wiki/Linear_Tape-Open) (the standard form factor of Linear Tape-Open magnetic tape drives), LTO-6, has a raw data capacity of $2.5\ terabytes$. Currently, future generations of LTO are already planned, all the way up to LTO-10. So, let's go with LTO-10 as our storage medium.
LTO-10 has a planned raw capacity of $48\ TB$. At a compression ratio of $2.5:1$, we should be able to store $120\ TB$ on one tape.
$$
\frac{30\ ZB\ of\ storage\ needed}{120\ TB\ per\ tape} = 250\ 000\ 000\ tapes
$$
Using [this product](http://www8.hp.com/emea_africa/en/products/storage-media/product-detail.html?oid=5336403#!tab=specs)'s specifications as the basis for what a future-gen's specs might be, the mass of all those tapes would be $250\ 000\ 000 \* 0.27\ kg = 67\ 500\ 000\ kg$, or about times the mass of the Titanic. The volume for all those tapes would be $11.3\ cm \* 2.79\ cm \* 11.1\ cm \* 250\ 000\ 000 = 87487\ m^3$, or roughly 0.4 times the volume of the Hindenburg. As of writing this, you can [buy this LTO-6 tape](http://rads.stackoverflow.com/amzn/click/B00UULISF8) at 10 for 320.00 USD, or $\$32.00 \* 250\ 000\ 000 = \$8\ billion$, or the [value of Spotify](http://www.wired.com/2015/04/spotify-worth-8-billion-not-crazy-sounds/). According to these numbers, I think your Super Star Destroyer-size ship is probably a little excessive.
Of course, your ship and its payload will have to be maintained and piloted somehow. I don't know if you want to allow robots to perform the routine maintenance and piloting, or have some small group of humans with bodies awake throughout the journey...that would add a layer of complexity to your ship design, for sure. Or you could have some ungodly combination, where you have a few human consciousness' plugged directly into the shipboard controls and sensors, able to maintain the ship. That actually sounds like a pretty awesome plot setup.
The good thing about these tapes is that they have very easy requirements. It looks like the ship library they are to be stored in should be temperature- and humidity-controlled at ranges between 5° to 23° C, and 20 to 60%, respectively. And that's about it. The rest of your ship and its energy is dedicated to just being a ship.
Let's say we use [these bad boys](http://www8.hp.com/emea_africa/en/products/tape-automation/product-detail.html?oid=5113922#!tab=features) for our data library. Of course, we'd probably have a custom build in our ship, but I'm just using these as a basis for comparison of specs. Also, I'm assuming data transfer rates are static over the next 50 years. We'll need $2\ 500\ 000 \div 12\ 006 = 20\ 823$ of them to hold all our brain tapes. The bad thing: these are probably crazy expensive. I couldn't find a number, but I can only imagine. The good thing is the R/W speed. If we were to use a single drive to read out all of the tapes it would take:
$$
\frac{30\ ZB}{400\ MBps} = 2\ 377\ 000\ years
$$
Since we were RAID 10 redundant, we can go ahead and cut this number in half on the read side, when we get to our new home planet. In order to cut the total read/write times to within 1 to 2 years, we'd need about 1.5 million tape decks. At about [\$5,500 per drive](http://www.newegg.com/Product/Product.aspx?Item=9SIA7092CP4506&cm_re=lto-_-9SIA7092CP4506-_-Product), they would cost us about another \$8 billion.
But with our fancy tape libraries and reading decks, we would have all the reading done in
$$
\frac{30\ ZB}{138\ TB/hr \* 20\ 823\ libraries} = 435\ days
$$
Not too bad, considering.
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I've posted a detailed sumary of brain/computer correspondence with timeline and my projections [on another Answer](https://worldbuilding.stackexchange.com/questions/9875/how-powerful-of-a-computer-do-i-need-to-simulate-and-emulate-a-human-brain/14117#14117) before.
Look at the graph. 50 years is a no-brainer (pun intended) for being able to simulate a brain with a far greater level of detail then needed given the understanding we already have.
The study of the brain is funded to a pittiful level compared to how much society spends on everything in total. If it became a priority and everybody put in the price of a movie ticket, **it would be done** in a few (single digit) years, mainly due to time needed to fabricate new designs of hardware.
As for "duplicating", the only way of scanning known now is destructive. We don't know if it's physically possible to scan the necessary level of detail using non-invasive techniques. Nanotechnology might be applied to crawl around inside and make maps, or take the tissue apart *and put it back together again*.
That could be an interesting part of the story: destructive scanning was used to depart, and they will work on the problem of building a replacement organic brain while en route. They have time and nothing better to do, but few physical resources and rationed processing power. Should poets be left on the shelf to devote more run-time to the biologists?
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Upload, yes. The data storage requirements are extreme but not beyond what T+50y tech should be able to provide in a crash-priority program such as this. We don't need to understand the brain, T+50y tech should also provide enough compute power to emulate the brain at realtime speeds. (If Moore's Law holds we should have supercomputers at this power level at T+20y. Since extreme parallelism is acceptable I can't imagine this target not being hit.)
The other half of your question is an unknown, though. We simply don't have enough understanding of the brain to know if we could build a functioning brain with memories or not at T+50y. However, this would not be a showstopper--in a do-or-die situation like this the ship would fly anyway even if they don't have any download system in place. Bring a whole bunch of fertilized eggs in cold storage and bring the computer-encoded DNA of even more people, along with the coding for everything that makes up a human egg.
The thing is the one thing you do have plenty of at that point is time. Live in the computers until such time as it becomes possible to download--not that I'm at all sure that people would choose that route. I strongly suspect you would end up with a society of computer-housed minds and tele-operated robots for when something hands-on needed to be done.
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If you can upload a human mind into a computing device, then you've essentially reached the point of technology singularity.
A space going vessel is the logical place to keep the computers in which the minds live, but why seek out planets or recreate organic bodies at the other end? Minds living inside a computer are free to generate any simulated environment they desire, including any simulated body they might like to present as their avatar. We already have primitive examples of that in virtual reality environments such as Second Life. What if our computing power was such that we could host full human minds in realistic but user-determined environments?
You may find that your minds, accustomed to the God-like near-instant fulfillment of their needs and desires at-will, may be unwilling to leave their simulacrum to return to physical reality.
The minds become the spaceship. They don't need a planet to live on. Having left meatspace behind, they live in cyberspace full time. A dynamic, digital reality continuously shaped and shaping the minds within.
The practical acquisition of raw materials for energy and propulsion to keep the mindship going is achievable without having to set organic foot on any planet or asteroid by using remotely operated drones or direct scooping of space-bourne gasses, so why bother with fragile, clumsy organic bodies? Physical space, improvements to the ship, computing power, and the continued exploration science can similarly be explored using simulation and drones.
The definition of a singularity is that you can't see beyond its surface. Likewise, with our technological singularity, we can see the surface, the starting point, but our predictions become increasingly hazy the further past that point we go. However, given the natural human desire to grow, it's likely such minds would desire additional computing resources. More memory. More processing power. Improved mind design. Improved psychology. With ever increased (and faster) intelligence, these trans-human minds would soon become both unrecognisable and unfathomable to their organic ancestors, and a new race, existing simultaneously both in space and in cyberspace, is born.
[Answer]
**I don't think this will work.**
At least not in the timeframe stipulated. The human brain compares to the modern computer like this:
[brain](https://www.sciencedaily.com/releases/2014/01/140116085105.htm):
* 1 exaFLOP: (x10^18th) floating point operations per second
* integrated cellular-scale structures for computing and storage
* takes less power than a 100 watt light bulb, or 1/5 a humans' metabolic energy
* adaptive neural network / architecture
* research beginning to suggest quantum state
* (on average) 100 billion neurons, 10-50x as many glial cells
[K supercomputer](https://www.scienceabc.com/humans/the-human-brain-vs-supercomputers-which-one-wins.html) (Japan, 2014):
* 10.51 petaFLOP: (x10^15th) floating point operations per second
* discreet components for calculation and storage
* draws 12.6 megawatts of power
* solid state architecture
* binary state
So the prospect of completely recreating the brain based on what we can technologically achieve now is just not going to happen. Man-made computers are still very far behind replicating even 1 human brain. If you were to build enough K supercomputes to achieve parity with 1 human brain, it would require 1.26 gigawatts of electrical power. For perspective, that is about 1/10th the power used by New York City, or the entire output of one nuclear reactor.
The prospects are better for preserving the brains themselves, and especially if they are still attached to the bodies, so they can assist in trying to rebuild their society when they get where they're going. Were I trying to design an ark-like colony vessel to save the species, I would rather preserve genetic samples and worry about keeping enough live colonists going. That would be a difficult enough prospect to achieve given a centuries long journey through space without having to worry about keeping a computer network that complex operational.
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I think it **may be possible**, so long as the inputs, outputs, and internal variables of certain neurons or lobes of the brain can be narrowed down and replaced with technology that can perfectly accommodate the replaced pieces. Most likely through **Nanotechnology**.
Some preliminary numbers on all of this;
The most convenient method of deploying nanobots is to swallow a pill full of them, but then you still need to cross the blood-brain barrier. The [pore-size](http://www.medscape.com/viewarticle/770396) is typically <1nm, but with a bit of cellular engineering (carrier-mediated transport), we can increase that to **a diameter of several nm**. [Modern SSDs put 10 terabytes on a 63,500,000nm drive, which is **173kb per nm**... And that's enough for [a simple OS](http://mikeos.sourceforge.net/write-your-own-os.html). And in 50 years time, who knows how much that will improve.
The current bottleneck for this is computer processors. The transistor we assume to be [the smallest possible](http://www.cnet.com/news/end-of-moores-law-its-not-just-about-physics) is still [a massive 5nm](https://en.wikipedia.org/wiki/5_nanometer), and processors are a network of transistors; even the simple [Intel 4004](https://en.wikipedia.org/wiki/Intel_4004) had 2,300 (which would be **11,500nm** if implemented with 5nm transistors).
Though this boundary could perhaps be surpassed if some of the [logic gates for the ALUs](http://www.csc.villanova.edu/~mdamian/Past/csc2400fa13/assign/ALU.html) were made out of diodes instead of transistors, it is more likely if the Nanobots operate as an emergent distributed processing network; each one communicating with others nearby in order compute, sort of like the human brain itself.
For purposes of scale, Neurons themselves are between 3000nm and 18000nm, so plenty of these <10nm nanobots may have to be deployed in order to assure a reliable network and a strong signal. [A functional CPU](http://boards.straightdope.com/sdmb/showpost.php?p=10297615&postcount=4) would also need a register bank to keep track of control flow, and an ISA to allow the CPU to 'run software', but that's a feat for engineering to surpass.
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# The problem with brain uploading
A lot of brain uploading stories have a fundamental problem, which is that their 'upload process' is more like 'create a clone of the original' than 'transfer your actual consciousness into the machine'. They then ignore the difference, or the fact that these even ARE different. People have been wondering that about [Star Trek](https://www.reddit.com/r/AskScienceFiction/comments/6dilbk/star_trek_is_a_transporter_just_essentially/) for a long time. The people in charge of the Trek IP eventually commented officially to the effect of 'That is not how it works. If anything we did ever implied that's how it works, I'm officially declaring it non-canon'.
Consider: I have a piece of software. Is it Bob, or a piece of software that thinks it's Bob? If it's Bob, what happens if I make a copy of it and fire the copy up on another computer? What happens if the computer is turned off, and then back on?
# There is a probable answer, but no hard science
The most likely answer is continuity of existence. You exist because your brain is running something like software that constitutes you. If your brain's organic components are slowly, over time, replaced with electronic ones using ... bioengineering technology so far advanced from what we can do that it's mostly hypothetical - then it is possible that "you" would eventually have a wholly cybernetic brain. This could then be installed into, for example, a bank of braincases in this ship.
Would that really be you? Would it be something an awful lot like you, but not sentient anymore? Or something an awful lot like you, except warped and now dead to emotions?
Modern science cannot answer these questions, because we do not have a sufficiently deep understanding of what consciousness is. We cannot say whether a given entity is 'conscious' or not, because we don't know how to define consciousness precisely enough.
As for metaphysics, either there is no such thing as a soul, or modern science can't detect them in any way. You can't prove the non-existence of something, so this means hard science cannot tell you anything about what a soul is, if they exist. So you can't answer the question from the metaphysical angle either.
[Answer]
I'm going to start with I think that is actually a great way to fly across the cosmos.
However, I don't think uploading 'consciousness' is something we can do with current understanding of the brain. Our first problem to solve would be just to be able to record memories to digital format in such a way that we can 'recall' it. I suspect that will be our first step. More and more people are using things like Google-glass to record their lives, the next step would be to record more. Using external/artificial devices as backup memory. Once we can record and play back memories and experiences we will be on the road to uploading conscienceless. Memories are a rather simple step compared to the next.
It isn't just that you need to have enough processing power, or harddisc/memory to hold the whole personality, memories and experiences, you also need to be able to simulate the interconnectedness of human thought. While we continue to learn more and more about how our brains work, we are still a long way from that.
So the next step would be if we can up load an animal, such as a well trained dog, can we take a cloned copy of the dog 'write' back to it? Will the dog remember it's tricks? Will it act the same?
Writing memories to hardware storing them and then writing them back to wetware is still not allowing the person to 'live' while in the machine, it's just making a 'backup' that hopefully can be stamped onto a new copy, (or even the old body out of cold storage) to let the person continue where they left off.
The last and be far most difficult step is to allow people to actually be conscience while in the machine. I would certainly not volunteer to be the first test subject unless I'm dying from something. The first problem here is we don't really know what consciousness really is. So how can you model something if you don't know what it is?
I suspect that after we start having hardware backups connected to our bodies and networking becomes more ubiquitous experiments will start with 'traveling' through the networks to 'be' somewhere else, a VR type existence. This would help prepare people for actually being separated from their bodies. Most of us today would likely go insane in fairly short order by removing us from our bodies, none of our expected inputs available, our body not telling us our but is sore from sitting, our bladder is full, we're hungry, not to mention sight sound and smell etc. We would somehow need to be able to use external sensors to get input.
So in 50 years I think it is possible we will have the ability to record and play back memories and experiences. Might even be able to share them with others. Which makes me think a whole new wave of porn would be born. You wouldn't just 'watch' you could 'experience' things. Many other interesting things could be done, both good and bad. But I think we'll be short of a full upload download yet. Not for lack of equipment capabilities, but lack of understanding how everything interacts and the ability to program for such a monumental task. Though I expect we'll have Conscious AI's which would dramatically help us understand what we need to do.
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Twins have the same brain structure but have different consciousness which means that you can not upload or export the consciousness of a person.
Another option would be killing the original consciousness and creating a digital copy if the technological levels allow it.
You might be able to enter a digital world the same way we do in Virtual reality video games.
If one wanted to make an immortal brain, it could be theoretically possible to do so by supporting a brain living in virtual reality supported by machines. We can already support people in comas and they are just dreaming forever.
The brain could degrade over time and to this day we do not know of any mechanism go keep a brain living forever.
One is be able to copy the memories of human with enough space and processing power, but understanding how every different psyche works is hard by itself, let alone copying it.
Is the human consciousness the result of memories or can two people experiencing the same exact memories have different consciousnesses? This question is hard to answer with empirical evidence and there's no way to study it with our technology as for now.
Assuming it was possible to copy a psyche, which with enough technology us likely possible. Even if consciousness is unique, like a "soul", everything can be replicated with enough skill.
Just as an artisan or an artist can do the same craft twice and make it look identical, but at the microscopic level they are different, it only matters that they look and give the same feeling.
Once the mind is uploaded, it would need access to internet if they wanted to maintain it alive, a single physical copy can be destroyed and computers do not last too much.
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Absolutely. The human brain is nothing but a chemical computer, after all, and it's this chemical computer that gives rise to the mind. For me, [the problem of causality](https://en.wikipedia.org/wiki/Dualism_%28philosophy_of_mind%29#Causal_interaction_2) is a watertight argument against any notions of duality. Once one embraces monism, I feel that the possibility of transferring one's consciousness to other substrates becomes obvious.
Since dead organic matter as we know it now tends to spoil over the course of centuries, I think an intermediate step may be necessary if we're going to realistically make this happen within the next 50 years. I think mechanical bodies would be a better bet in terms of durability and longevity in storage. And if things end up taking longer to develop than planned (they almost always do, it seems), the mechanical bodies wouldn't necessarily have to house the consciousnesses controlling them. They could be "thin clients" (or "thin avatars" in this case, I guess) for the consciousnesses still in the megalithic computer on the "lifeboat." That would allow the survivors to then build organic bodies using what's available on whatever planet they end up on.
Of course, cryogenics is another possibility. ~~But that would be very energy-intensive compared to just making hyper-durable robot bodies that would remain switched off for most of the trip. My money would be on the robot bodies.~~ Totally a possibility, because space is cold and most of the trip would be done with solar sails or something else of similar efficiency, as @bowlturner pointed out in the comments below.
Note that you wouldn't need 3 million robot bodies, of course. You'd just need enough to allow everyone who needs to interact with the physical world to be able to do so. More is better to a point, but 3 million seems like it would be excessive.
For technological paths that would likely lead to the vision you have here, look at [neuromorphic computing](https://en.wikipedia.org/wiki/Neuromorphic_engineering) and [biocomputing](https://en.wikipedia.org/wiki/Biocomputer). Again, due to the fragility of organic matter, I suspect biocomputing may be a dead end for transporting consciousness over the span of centuries. However, I also suspect it would prove to be very useful when it comes time to start creating organic bodies on the new home planet.
Not sure if this has enough hard science for you, but hopefully it's helpful all the same!
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I have read the laws of magic and related articles, that is why I came upon this question.
For my world building I have been working on a magic system, it took me quite a while to find something even remotely close to what I have in my chaotic mind.
To be short the magic in my world exists in mana (lifeforce/ essence of life / ...). My magic does not discriminate, everybody can use magic, if they really want to. (Although there can be political or cultural restrictions). To cast spells, a mage has to gather some mana either form his surroundings (sucking it dry) or from within himself (the mana muscle).
The era my world is currently in is a new one, only 1000 something years old. the previous one ended with a series of great wars, rendering much knowledge lost, especially magical knowledge. I did this to keep a feeling of wonder and to be able to add in rules as I go.
Now, I have also added in that magic has different interfaces to interact with, meaning that two mages don't necessarily call upon their mana in the same way. The most common way is using spell circles and spoken words. The more basic spells can be performed by imagining the spell circle with your mind's eye, while the more complicated ones need real world spell circles and incantations.
I also have at least 3 other ways of 'doing magic'. One is a witch like way, a sort of nature magic controlled more by emotion then by logical sequences.
Another one is shadow magic. This one is also more controlled by emotion but has no bonds to nature, it is also highly volatile and hard to control.
The third is some sort of desert magic, with jinns being the practitioners.
I probably add in a bunch of more ways to interact with magic. My question now is does this negatively affect the credibility of my magic system? Does it make it seem less reasonable? I tried judging this by myself but to me it just always seems okay.
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The obvious analogy to me is programing languages. Each programing language I write in works differently, some are object oriented and some are functional. Lisp and C have very different feels and paradigms used when programing them. And yet, in the end, the language I write gets converted down to machine language and all runs on the same computer. They have very different approaches to getting there, depending on what is easier for me to program, but they all 'compile down' to the same basic machine language.
I would go with the same analogy. Magic at it's root works the same everywhere. However, it's nearly impossible to control the magic directly, by trying to push the mana around with your mind bit by bit; humans simply can't process all the steps needed to do it. So we have figured out shot hands, magic 'languages' that interface with the mana and allow us to control it.
I think this can be done realistically. There are some small things you can add in to help it feel more justified.
1) Have some shared steps across all 'languages'. For example perhaps every language has some sort of shape or structure, like your casting circles, which is used in casting in some way. Maybe for shadow magic it's thinking of a pentagram (with no need to draw it) while casting, and for nature magic they wear moon shaped necklaces which they focus all their magic through. The shape, and how it is used, varies across languages; but In every case SOME shape is used as a focal point for the magic, implying that the raw magic needs a shape framework as the start of their spell. Likewise imply that the final steps of casting magic is very similar, the step that takes whatever spell you have constructed and combines it with magic to make something happen. Everyone uses a similar approach here, the equivalent to 'compiling' their spell. The more subtle commonalities you put in casting of the different languages the more they feel like different interfaces that overlay the same core magic.
2) Any magic type can theoretically do the same thing. Some languages may be better at casting a spell, but every spell can theoretically be duplicated in any magic. Perhaps it would take far more focus and skill to control nature using your circle magic, so much that it's not worth the effort to do, but in theory you can do it. Since they all use the same magic underneath anything doable by one must be doable by the other. It's simply that some approaches make it easier and faster to figure out *how* to cast the spell to do what you want.
3) If you tie some magics to emotions your need to address a connection to all magics as emotion based. Perhaps the non emotional magics still require a certain mental state when casting. The circle magic requires clearing emotions out of your mind, death magic requires a sort of bleak sense of how worthless life is, healing magic requires a drive to heal and help on an emotional level. In effect every magic requires a certain 'emotion' to work with. Some magics are unique in that they can work with many emotions, and be effected by how emotional they are, while other magics simply require a certain way of thinking or emotional desire to cast the spell, but their effectiveness isn't otherwise as strongly tied to emotions as others.
4) Finally, I would hint that these are all approximations of *real* magic. You said magic knowledge was lost, I would use that as a way to throw in foreshadowing. Perhaps in the past the true mechanisms of how magic worked were better understood, but the full understanding was lost. These magic languages are approximations used to make casting easier, the people of the past knew that. The people of the present don't understand that their magic approaches were designed simply as easier interfaces for controlling magic. However, you can always through hints and foreshadowing of this fact, run into old tomes of magic or myths which allude to the fact. Done well you can tell a savvy reader the truth of how magic works even as the protagonists haven't put it together.
If you have magic words I would suggest implying that the magic isn't in the words. Instead the words are simply a memorized route method of casting magic. Perhaps the words mean nothing, it's the thoughts that we go through when articulating the words. However, the people casting the spell don't know this, only that when they say abracadabra magic happens, so they keep using the magic word.
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I think you can maintain credibility with your magic system. I would feel comfortable claiming we have similar verbiage in real life describing martial arts. All of the martial arts are going towards the same goal, but the paths they take are strikingly different. Given that I can see real life corollaries, credibility should be possible.
If you wish to use this martial arts metaphor to maintain credibility, I recommend carefully crafting the way people view the world to match their particular magic style. If someone has "witch" style magic, they should view "holy" magic in witch-magic terminology, trying to explain how holy mages do their things in terms of the trinkets and familiars and spells witches use. A holy mage will describe the same abilities using different verbage. A natural magic worker might view holy magic as a very strict version of growth without much room for self expression.
Each style should be able to do *anything*, but there may be things which are hard to do using one style, and easy to do in another. If it is hard to do in a style, individuals who practice that style should develop lifestyles where they don't have any *want* to do things that are hard in their magic and easy in others.
As an example, Xing Yi, a Chinese martial art, focuses heavily on how to attack on straight lines. One would be foolish to believe they can't attack on curves -- such a mistake would be rectified shortly. However, their techniques function *better* on straight lines. They prefer it. Accordingly, they will structure their life such that many of the obstacles they want to overcome appear on straight lines.
In contract, Baugua, another Chinese martial art, focuses heavily on how to move in circular motion. Think they can't move in straight lines for a moment, and you'll regret it. However, their technique functions *better* on circles. They prefer it. Accordingly, they will structure their life such that many obstacles can be dealt with by rotating around them to find a better angle to attack.
If you ask a practitioner of Xing Yi about Bauga, they might say "sure, circles are nice, but if I can get ahead of your movement ever so slightly, I'll strike out in a straight line, and pulverize you. Circles are useless in comparison to straight lines. A practitioner of Baugua, when asked about Xing Yi, might say, "Yeah, they can put a lot of power on straight lines, but I'm not going to let anybody keep me on a straight line. I'll weave around, and when they weaken themselves by attacking and missing, then I'll strike them along a curve they can't predict."
Both styles are known as "internal" martial arts, and it is a commonly accepted attitude that they are "climbing the same mountain, just taking different routes." In fact, there's a third traditional internal martial art, Tai Chi, which takes even a different route. All of them go towards making the internal self better, but they do it in different ways. They each have different verbiages to describe the others, and practitioners will organize their life based on the strengths and weaknesses of their art.
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I would say it partly depends on how easy it is to collect mana to use in the spell and how fast it replenishes itself.
I would guess that small spells would be rather common, easy to use and the person could easily recover from it. Collecting mana from other sources would be more difficult and (generally) require a concerted effort to gather in preparation.
I would also expect that gathering too much from a plant or area would cause lasting damage to the area, encouraging more 'reasonable' usage.
Taking these kinds of things into account, it could make the magic system reasonable.
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You should peruse the D&D *Dark Sun* supplements. They use a similarly "negative" mechanic for magic. (Pretty much exactly the same one, minus the different ways of gathering energy.) It definitely makes magic more feared, but it works in that (nigh-apocalyptic) setting.
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Say I wanted to create a civilization of people who, in accordance with a vow to never harm plants, refuse to practice agriculture or animal husbandry, instead relying hunting and fishing for all of their needs. Is it conceivable that this society would ever produce a city with tens of thousands of people?
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Historically cities have developed first in those place where the agricultural production exceed the needs of the farmers, allowing also to feed those covering "non productive" roles (non productive in the sense that do not directly produce food) like priests, guards, scribes and so on.
When relying on hunting and fishing that step has never been taken: while farming requires being stationary in a certain place, hunting and fishing has to follow the preys, and the larger group it has to sustain, the more frequent the movement has to be to prevent depletion of the locally available resources.
By the way, tens of thousands of people are also challenging for a simple state city which do not have a developed trade with neighboring communities.
And it is also very hard to build a city without harming any plants: trees and grass are not going to get out of the way just because a bunch of noisy humans are there, like most animals would do.
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**Trade and Fishing**
Humans have developed high population densities in the absence of agriculture.
In the Pacific Northwest of the United States and Canada the Chinook, Salish, Tlingit, Haida, Makah and other indigenous peoples had large villages (up to 400 or more people) with hierarchy (kings rather than chiefs in Nootka Sound) and social stratification (including a widespread slave trade)
These nations had no agriculture prior to European contact, instead relying on the seasonal salmon runs to support their large and sedentary populations. They supplemented the salmon with berry collection, whaling and hunting.
Trade was extensive amongst these nations and included everything from obsidian extracted in the Cascade mountain range to slaves taken as far south as what is today California.
You could conceivably have much larger polities forming from alliances of villages that could make actual cities based on especially productive fisheries and hunting grounds that are also located somewhere that trade is lucrative
Edit: Short Answer is you can get decent sized sedentary communities but not in the tens of thousands. Consider altering the flora or fauna to justify even more lucrative fishing and hunting or having your cities be in the low thousands or a few fortified villages (think Celtic Oppidum) so that your hunter gatherers have settlements and an administrative core ruling over a rural populace
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I think that it is a really nutty ethical system which permits hunting animals but forbids harming plants. But it is your story.
It is possible to use plant products without harming plants.
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And at first sight one may wonder why the lemon tree - if it had consciousness and desires - would want pieces of it to be broken off and eaten.
But if there are no nerve connections between a plant and its fruit - which is easy to achieve since plants have no nerves - the plant will feel no pain when a ripe and ready to fall off fruit is picked, or when a fallen fruit on the ground is picked up and eaten.
The function of fruit is to be an edible container for inedible seeds. Animals eat and digest the fruit, and then excreate the undigested seeds in their poop. Thus the seeds are carried far from the parent tree and are deposited in a little bit of fertilizer.
And I think that berries also function that way, from the point of view of berry bushes -if berry bushes could have a point of view.
And grapes include seeds, except for seedless varieties developed by agriculturalists, so they should function like fruits and berries, and maybe your hunter-gatherers will think that way.
What about nuts? Every nut which a human eats will never grow up to be a tree, so being eaten will not be good for that particular nut if that nut needs to become a tree. But if humans have a habit of picking up and collecting nuts to eat, they will lose a percentage of those nuts which might land in spots good for sprouting. So if a nut is not considered to be an entire plant, but a tiny part of its parent tree, and if that tree is considered to have some sort of need to reproduce, and get some sort of benefit from having growing offspring, then collecting nuts to eat and sometimes losing some of them can be considered to be good for the nut trees.
And considering a nut, a stage in the life cycle of a nut, to be not a tree and thus not a plant, might seem like thinking up a goofy loophole to blatently violate an ethical rule. But humans do that all the time. For example, humans constantly violate the rule against murder by killing embroyos and fetuses, despite them being just as obviously human as a person in any other stage of the human life cycle. And technologically challenged hunter-gatherers like the desired group would kill or abandoned to die unwanted newborn infants.
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<https://en.wikipedia.org/wiki/Infanticide#Paleolithic_and_Neolithic>
Thus your hunter-gatherers might think that nut are not yet plants and so it is right to eat them.
What about mushrooms? Fungi are classifed as a separate kingdom of life from plants. The visible parts of mushrooms are just the parts they use to spread their spores, and the main bodies of mushrooms are underground or inside infected tree trunks.
Would the hunter-gathers be aware that mushrooms aren't plants, or aware that the visible mushroom caps are disposable spore containers and that eating them will not harm the mushrooms if they think mushrooms are plants? I don't know.
If the hunter-gathers see mushroom caps growing out of living trees, will they think that the mushroom caps are parasites harming the trees and that picking and eating them will be helping and not harming the trees? I don't know.
And it is possible to build a city in a rather barren area with little or no plant life growing, and perhaps to build around any widely scattered plants which do grow there.
The ground floors of buildings can be made of dirt, or sod, or stones. The walls can be made of stones. The roofs (and ceilings and upper floors, if any) of low technology buildings are usually made of wood. To get wood without harming trees and thus plants, they would have to carefully trim away superflous branches as modern tree doctors sometimes do, or collect fallen branches and trees from the forest, or collect driftwood on the banks of rivers, lakes, and seas.
And it is perfectly possible to build vaulted and domed ceilings and roofs out of stone or bricks. Wooden centering is often used while building arches, vaults, and domes, but they could collect dead wood or build vaults without wooden centering, which has been done. Legends claim that some vaulted buildings were built by making giant sand or earthcastles in the desired shape, covering the sides and top with stone or bricks, and then digging out the sand or dirt from beneath. Those are just legends, but that could possibly be another real life technique to build vaults without centering.
Any bricks used would have to be inferior, but widely used, sun-dried bricks instead of fired bricks.
Or buildings could be roofed with tent roofs. If they hunt, they can make leather out of animal skins and sew a lot of leather pieces together and suspend them over the rooms in the buildings, perhaps using poles made out of dead wood they found to support the leather roosm.
Possibly the city dwellers could advance enough to become herders and domestic animals, keeping them in walled meadows to graze. Of course that would be harming the plants the animals eat. But maybe they could think up a sneaky loophole to the rule agaisnt harming plants, for example claiming that it was the livestock that hurt the plants.
Or possibly they drive herds of wild animals into a wide and fertile valley and wall up the only pass into the valley so the animals can't get out, and then enter the valley to hunt them, and build their city nearby.
Possibly they follow nomadic herds of prey animals on their regular migration routes. Possibly there are a few places where the herds stop for long periods of time each year, and the hunters build seasonal tent cities at those places and eventually replace the tents with stone buildings used during the seasons while they are there. So they would live in several different cities in different seasons of the year.
Late Medieval Ethiopia was a civilized society with agriculture and permanent villages, towns, and cities. But the king of kings, his court, and many soldiers, usually travelled constantly, forming a vast tent city with thousands of people wherever they stopped for the night. The permanent capital, Gondar, wasn't founded until about 1635.
And I guess that a travelling tent city with many thousands of persons could support itself by hunting if they followed vast herds and had riding horses to go hunting far from where ever they were camped at the moment. The Sioux sometiems formed travelling camps with thousands of men, women and children for months at a time, so you need to make hunting somewhat easier for your people than it was for the Sioux if you want them to live in vast tent cities all year round.
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Consider the requirements of a city of tens of thousands. That requires significant movement of resources into the city just so that the people can cook and eat. In order to have that movement, thousands of people have to be motivated to be hunting / gathering firewood and carrying that into the city. You also need water brought in. You are talking about some kind of slavery or religious movement.
When we look at history prior to agriculture, there were places where thousands gathered. Places like Stonehenge were gathering places. But they were for special gatherings, not settled cities.
If you want a city, one way is to make it a place of religious pilgrimage where only a few religious professionals live, but where nearly everyone comes several times a year. It would need to have the places for people, but most of the year, those places are empty. Add a justice system and small groups of people will visit throughout the year. Food, firewood, and water can be brought in for those large gatherings without major harm to the environment.
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Gleaned from this history.se question: [What surface area per person is required for hunter-gatherers?](https://history.stackexchange.com/questions/3205/what-surface-area-per-person-is-required-for-hunter-gatherers) the answer cites the following:
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> Clark and Haswell (1970) estimate that at least 150 ha of favorable habitat per person is needed to secure an adequate food supply. In a moderately favorable habitat, these scientists estimate that 250 ha per person would be required. ... In marginal environments, such as the cold northwestern Canadian region, each person needs about 14,000 ha to harvest about 912,500 kcal of food energy per year (Clark and Haswell, 1970).
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So assuming a highly favourable environment, and further assuming the area to sustain strict hunters is equal to that of hunter-gatherers, a city of 10,000 would need an area of 150,000 hectares (~370,000 acres, ~1,500 km²).
That isn't a completely unreasonable area, but as the population grows those hunters will need to travel farther and farther out to find prey and bring it back. Anything above 10,000 I think would begin to test the concept of city; there would be enormous pressure to undergo fission and split the population into smaller clusters scattered within the hunting area. And once split, they would begin competing with each other.
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The current answers all base themselves on historical realism, but the OP does not specify this as a requirement.
The obvious answer is therefore mega-fauna. A city requires large amounts of food, your carnivorous civilization gets this from humongous creatures that cross the region the city is based in frequently and in large enough numbers to provide that food, while also being huntable by a small, rag-tag band of heroes.
This is essentially an extension of the Greenland/ whale hunting society in a comment on the question, but with fantastic beasts thrown in.
For bonus points, this migration could take place through natural portals so the local area does not have to support these creatures out of its own resources. Much like the Perfectly Normal Beasts in the 5th Hitch-hikers book.
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The direct answer is very likely "no", as many others have laid out. Agriculture is the easiest and most efficient way to convert solar energy into ... abundance of something we can eat, basically.
But let's just say we want a "yes":
### An inferior or vassal civilization is doing agriculture for them
Your people don't do agriculture. However, they're good at conquering people living in their outskirts that *just happen to have significantly different characteristics*: blond instead of brown hair, blue instead of black eyes, speaks a different language, practices different sets of belief, etc. In short: another civilization, for any practical purposes.
You enslave them and tell them to provide for you, or else. They eventually resorted to agriculture, for the same reasons above. Strictly speaking, you don't harm plants, the vassal civilization do. Your civilization then can just keep having (pretending) the moral high ground ever since.
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You can get around the thou-shalt-not-harm-a-tree mandate if you allow the collection of produce that has fallen to the ground (i.e. "That which Nature hath offered, directly").
In addition to the answers above, this lets you extract marginal nutrient content from non-animal sources, especially nuts/seeds which are decently high in fats that a lot of game animals will be lacking. Cultivation of those trees would be a form of agriculture, but more like landscaping than active farming. There's a number of fruits that are okay to harvest from the ground as long as you're checking every day to avoid fermented/rotting examples.
This avoids the whole "harming by harvest" angle, unless they understand that dropped fruit/nuts/seeds are how plants propagate themselves and find the interruption of that cycle objectionable.
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One of the main difficulties that have harped militaries from prehistory to the modern day has been identifying who's your friend and who's the foe. Many solutions have been used to solve this conundrum, but with metamaterials promising the ability to, partially, blend into the foreground the issue of identifying friendly forces once more rears it head.
So what are some possible ways to prevent friendly fire?
Some assumptions:
* The cloaking device comes in the form of either a trench coat or poncho like cloth that refracts that light.
* The cloak does not need much power to function.
* The cloak works by having a metamaterial bend and refract the light around the person. The cloaking is not perfect, if you look hard enough you can see a distortion. Similar to [this](https://www.youtube.com/watch?v=3f7rWzF8Ezo) depiction in the clip.
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There is no substitute for good organization, training and leadership. IFF transponders have existed for decades, and yet "blue on blue" (and its various non-NATO counterparts) incidents persist.
Even where super advanced high-tech cryptographically secured IFF systems exist, the transponders still get turned off in various circumstances, and the interrogation systems may not always be used all the time in all locations.
* Emitting an IFF query reveals your location.
* The nature of the IFF query signal may reveal to an intruder that they have been spotted, which may in turn prevent them from revealing their intentions or from being intercepted.
* Emitting an IFF response signal reveals your location. Perfect pinpoint non-back-scattering tight-beam communications are basically impractical in the real world.
* You cannot guarantee that an IFF signal (query or response) has not been spoofed by an enemy.
* An IFF system, emitter or receiver, may have been damaged and unable to function.
* IFF signals, either queries or responses, may be rendered unintelligible by various kinds of electronic countermeasures or environmental conditions.
And so on.
There are enough reasons why IFF can't or won't be used under various circumstances, that you have to train and plan for the eventuality that it isn't available. Gating all firing decisions behind an IFF challenge-response is very risky, and will likely end up getting people killed when their smart-guns suddenly refuse to fire, or everyone just lights up with a big "shoot here!" radio beacon due to a software exploit.
(also, you're probably all gonna get murdered by automated weapon systems and drones using passive thermal and audio and chemical sensors, because the battlefield is no place for things which move, act and react with the speed of a meat glacier, but that's a different topic)
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Directional IFF transponder.
Your active camouflage doesn't send any information in order to remain hidden. It does passively pick up the IFF transponders of your allies. Should these allies come within a certain range, the directional IFF transponder sends updates to that ally. Using networking this signal is then disseminated between all the other allies in order to minimize the electronic footprint of the cloaked people.
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As per [Demigans answer](https://worldbuilding.stackexchange.com/a/227822) re: IFF. Although I would specifically suggest IFF be built into the sights/targeting pods of friendly combatants. A soldier detects motion and acquires a potential target in his sights. Moving his finger to the trigger (not pulling it) activates an electro/optical or similar circuit which sends out a coded 'ping', a radio or laser light pulse in the direction of the target. If the target is a 'friendly' his or her suit/helmet/IFF pod automatically sends back an answering 'ping' confirmation of their identity. This appears in the users sight as blue (don't shoot') digital overlay on the targets image in the soldiers sight. The circuits involved work close enough to light speed to make human reflexes glacial in comparison so the soldier will usually never have a chance to pull the trigger which locks itself anyway. And on top of that the soldier has been trained from day in making shoot/don't shoot decision based on the info displayed in his targeting system.
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Your active camouflage does not extend around you in a complete circle. It's only active on the side that's facing the enemy. When advancing towards an enemy position, you'll be invisible from the front but your squadmates behind you can still see you (there's no benefit in hiding from them anyway). The opposite will be true when fleeing. The soldier would have manual control over the angle of effectiveness, but this could also be somewhat automated so that the system reorients itself as you (for example) flank your enemy and come up behind them.
You won't be able to see the friendly units behind you, but that shouldn't matter. The important part is that you can see the friendly troops that are between you and the enemy since that's the direction that you should be firing in. You would still have a problem in the case where you've surrounded the enemy and are attacking them from opposite sides at the same time, but cross-fire would still be a problem if you had 100% perfect visibility.
The only way for this type of system to be intercepted and used by your enemy is if they were behind you. If *that's* the case, then you've got bigger problems than your camo.
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As others have pointed out, you need an IFF signal of some kind. But an active IFF signal will ruin the stealth provided by your optical camouflage... unless the signal cannot be recognized as such without the proper key.
The IFF feature of the cloak will induce very slight variations in the distortion caused by the camouflage, on very specific wavelengths of light that get changed over time, according to an algorithm that uses a clock and a secret key. The principle would be essentially the same as when hiding text into a JPG photo image file using steganographic tools.
Without the proper equipment and key, the induced variations are extremely hard or impossible to detect, so the camouflage effect will be essentially the same as without the IFF feature.
But when the same algorithm + key that was used to generate the IFF effect is used to tune the pass-band of a very narrow-band filter so that the detector is restricted to "looking" only at exactly the right wavelengths of light at the right time, a detectable pattern can be seen on the cloaked figure or object. Only those with the correct key (and a clock that is in sync with the clock of the camouflaged person/thing) in their IFF detector unit can see it.
Complication: since the cloak works by manipulating existing light, the IFF will be less reliable when there is very little light available.
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This is for a story that I've been kicking around for years at this point and I always get hung up on how realistic one of my story arcs is.
I have an elected constable and town selectman that is participating in illegal activities in a small town. The town is currently served primarily by a county sheriff's office, but this constable wants to create a town police force with several of his loyal men as officers to provide a safety net for his criminal operations. Assuming he has the townspeople on his side, how would he establish this police force in such a way that it is officially recognized by the state (current manuscript is set in rural Arkansas)?
So far, I've been hingeing the creation of the department on approval from the town's primary governing body (a board of selectmen) and then securing funding. The more I think of it though, the more I think that there has to be some sort of accreditation requirement or process somewhere that I haven't heard of.
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## **The Town May Form Its Own Police Department**
[Under Arkansas state law](https://law.justia.com/codes/arkansas/2016/title-14/subtitle-3/chapter-52/subchapter-1/section-14-52-102/) a town has the authority to establish its own police department. Such a department is then subject to various [Arkansas laws governing the conduct, privileges, and duties of municipal police officers](https://law.justia.com/codes/arkansas/2016/title-14/subtitle-3/chapter-52/), and possibly one or more [statutes pertaining to State Police Officers](https://law.justia.com/codes/arkansas/2016/title-12/subtitle-2/)
Finally, they will also be subject to any Federal law pertaining to state/municipal police officers - as far as the Fed is concerned, city cops are just extensions of the State government.
## **But It Doesn't Need To**
[Towns in Arkansas may appoint Marshalls](https://casetext.com/statute/arkansas-code-of-1987/title-14-local-government/subtitle-3-municipal-government/chapter-45-government-of-incorporated-towns/section-14-45-109-appointment-of-marshal-and-other-officers) who have all of the powers and jurisdiction of county Sheriffs, including the appointment of Deputies. This possibly also avoids the restrictions and requirements that otherwise apply to police officers, and is probably why this option exists; rural town budgets are legendary for their paucity.
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The process is rather routine, if non-trivial. They'll need to incorporate as a township, if not already incorporated. Population requirements (and others) vary state to state.
The establishment of a new police department also varies state to state, and you can read up on the various state laws governing them. Certain requirements have to be be met (mostly concerning how they are staffed). For instance, this is Ohio:
Title 7 (Municipal Corporations) §737.05
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> The police department of each city shall be composed of a chief of police and such other officers, patrolmen, and employees as the legislative authority thereof provides by ordinance.
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> The director of public safety of such city shall have the exclusive management and control of all other officers, surgeons, secretaries, clerks, and employees in the police department as provided by ordinances or resolution of such legislative authority. He may commission private policemen, who may not be in the classified list of the department, under such rules and regulations as the legislative authority prescribes.
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Basically, the city government needs to pass ordinances, then hire a police chief who then has to hire out others to do the actual work. The police chief does not himself need to be a sworn law officer in some/most states (wouldn't have the power of arrest if he doesn't though).
Nothing in the statutes I'm looking at talks about having to register with the state government or anything like that either.
Such a town might find model laws/statutes with which to pass such ordinaces (basically, it's like a "fill in the blanks" bill example, so they don't have to write it from scratch).
Also of interest, in the United States, universities and transit companies (railroads, but also others) can establish their own police forces. The latter can do it according to federal law, the former having various differences state-to-state.
If you want this story in a particular location, consult the laws for that particular state. However, things tend to be similar enough that this might not be necessary
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**Replace the sheriff.**
<https://law.justia.com/constitution/alabama/CA-245675.html>
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> Whenever any prisoner is taken from jail, or from the custody of any
> sheriff or his deputy, and put to death, or suffers grievous bodily
> harm, owing to the neglect, connivance, cowardice, or other grave
> fault of the sheriff, such sheriff may be impeached under section 174
> of this Constitution.
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Having your bad guy incorporate his town for the purposes of creating a police force is not really the stuff of epic badness. I am kind of getting sleepy typing about it. But taking over the sheriff's office and using that office to provide cover is juicy badness. Having a prisoner taken from jail and coming to (scandalous!) harm and having the sheriff take the fall is more the thing a conniving bad guy would do.
If the sheriff is removed (or dies) the coroner becomes sheriff until governor appoints a new one. Coroner is in cahoots with your villain or at least is willing to take his money and follow instructions.
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Earth has its own current population, 7 billions individuals or so. Everything is going great: there are animals, rivers, houses and factories. The world as we know it (without pandemic!).
One day people wake up only to find out that something is wrong with Earth. Something related to the physics of the planet. Something that is making it roll down a hill and become more and more similar to Mars. With this I mean that, with a slow decline:
* Earth will not have animals anymore
* Earth will lose all the water
* Earth will become rocks and dust
* Earth atmosphere will become thinner and thinner
To summarize, in a couple of years (or 20 years? or 200 years?) Earth is destined to become deserted and lifeless as Mars.
Now the problem. I know where to start (Earth as it is now), I know where to end (Earth becoming lifeless as Mars), I don't know the tool to be used to make this transition.
What could be possible explanations to make the Earth do this shift to a lifeless status? Physics-related answers are preferred, but also not scientific (but credible) answers are ok.
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If Earth would lose its magnetic field, solar wind would have nothing stopping its interaction with the atmosphere.
This would result in molecules being split up there. If this happens to water molecules, they will be split into oxygen and hydrogen. While oxygen is massive enough to generally not escape the gravity well, hydrogen will leave to space. Over some millions of years water would simply be lost via this mechanism, and Earth would become a desert, with no life due to the lack of water.
Then over few more millions of years the atmosphere might be lost anyway, because a small fraction of the gases have velocities high enough to escape the gravity well, and if those are not replenished by volcanic activity they result in a net loss.
But mind it won't happen in the timespan you have in mind.
An alternative option is to wait for the Sun to go through its final life stage, where it will become so hot to blow away the planet atmosphere and oceans before swallowing it. But also this will not happen soon.
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It is possible there is is [a huge amount of water](https://www.newscientist.com/article/dn25723-massive-ocean-discovered-towards-earths-core/) deep in the mantle, perhaps three times as big as the oceans. It is not a big stretch to imagine there is place in the silicates for an additional 30% capcity. Let's say something (caldera explosion somewhere under oceanic floor?) makes the water seep down and bind with the silicates. The loss of life, atmosphere etc. follows naturally (though maybe not in the timespan given).
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**Rearrange the galaxy a bit.**
If you drag the star system [Eta Carinae](https://en.wikipedia.org/wiki/Eta_Carinae) (a binary or possibly trinary system, we're not sure) to within say 30 light years of Sol (it's currently at about 7,500 light years), then when it goes supernova (it's expected to anytime now) then it'll strip the atmosphere and most of the water quite effectively, but without knocking the Earth out of orbit.
Alternatively have a [Rogue star](https://en.wikipedia.org/wiki/Intergalactic_star) wander into our "local system (again, local would be within 30 light years or so) and then go [supernova](https://en.wikipedia.org/wiki/Supernova) for the same effect.
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There are some current issues currently recognized today as having significance to the planet's climate. (I am avoiding getting into any political discussions here about climate change, so i will keep my language as neutral and non-political as possible.)
You could make up a global warming theory, based partially on current discussions and partially using literary license, to create a plausible scenario.
For instance- there is discussion about the relationship of polar ice and the global temperature. Ice reflects solar heat into outer space; conversely, water is darker and absorbs more heat. More heat would cause more ice to melt, which increases the heat absorbtion etc. In theory this could be a runaway cycle.
What if all the polar ice would melt at one time? Say a massive volcano would erupt right at the north pole, spewing tons of molten lava all over the ice cap. This would melt lots of ice and raise the temperature right away (from the heat of the lava), as well as causing more solar energy to be absorbed in the future. You could substitute a meteor crashing into the North Pole as well, or any other sudden traumatic incident which would destroy the polar ice cap.
Now this by itself isn't enough. All this would do is raise the temperature of the planet, cause more water to enter the atmosphere and at best create a humid greenhouse. It might devastate planet earth, but it wouldn't turn it into a desert because the moisture would stay trapped in the atmosphere. So eventually it would rain back down again. And, as the planet's climate works in cycles, it probably would eventually completely recover its ice covering as well within a few thousand years.
You need a mechanism to turn the atmosphere dry.
Here again, we have a contemporary issues which could be borrowed and adapted for your purposes: the [Ozone Hole](https://en.wikipedia.org/wiki/Ozone_depletion).
The ozone layer is made up of a type of oxygen molecule, found naturally in the atmosphere. It absorbs lots of radiation from outer space. As the ozone layer gets depleted, it allows more radiation to reach earth.
This helps your story in a couple of ways. First off, the extra radiation will help speed up the warming and prevent the ice from reforming.
Second, the hole could be used to explain how Earth could lose the moisture. You could have a form of radiation which could react with water and break it into hydrogen and oxygen, with the hydrogen then leaving into outer space.
Or, with some more literary license, you could just make the atmosphere leave via the hole. The heat and added moisture creates such pressure that it presses the moisture-laden air out into outerspace.
Either way, this gives you a situation where the Earth is heating up and the ocean water is evaporated, but ends up escaping into outerspace instead of raining back down to Earth. You could thus conceivably make a time frame of a couple hundred years for Earth to look similar to Mars. (It wouldn't be anywhere near identical to Mars yet, but it would start to be comparable and would already have devastated life on Earth.)
To keep the ozone hole from healing itself, you would want to include a natural volume of certain chemicals like chlorine, bromine, nitric oxide etc. As radicals, they interact with the ozone layer and keep breaking apart the oxygen moecules, thus furthering destabling it. So for example, maybe mankind discovers that as the polar ice melts, a natural deposit of bromine is uncovered. This bromine reacts with the ultraviolet light (which hits earth stronger because of the ozone hole) and release bromine radicals, which then continue to enlarge the ozone hole.
Again, this is not strictly scientifically accurate, but it could work as a pseudo-scientific explanation and could be plausible to the reader.
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NASA has a nice article about why Mars' Atmosphere was stripped away.
[NASA's MAVEN Reveals Most of Mars' Atmosphere Was Lost to Space](https://www.nasa.gov/press-release/nasas-maven-reveals-most-of-mars-atmosphere-was-lost-to-space)
I favor bleeding energy from the planets rotating metal core in order to fuel energy needs...implying life that could construct such a thing(intelligence, as is commonly defined, is not actually needed...why not a bacteria that fed on the planets magnetic field; bleeding off massive amounts of energy?).
This could reduce the planetary dynamo the creates the protective magnetic field and allow the solar wind to strip the atmosphere.
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Interesting news! Astronomers notice a [relativistic jet](https://en.wikipedia.org/wiki/Astrophysical_jet#Relativistic_jets) from the supermassive Black Hole at the center of the Andromeda galaxy. The jet accelerates massive amounts of matter to relativistic speeds (80% of the speed of light).
[](https://i.stack.imgur.com/NXCkt.jpg) (image from [wikipedia](https://en.wikipedia.org/wiki/Astrophysical_jet#Relativistic_jets))
Bad News! The jet is getting brighter and it looks like our Solar System is going to pass through the jet!
Worse News! The jet pushes a heck of a lot more particle mass than the Earth's magnetosphere can absorb. As the Earth's atmosphere is stripped, the lower pressure causes evaporation of the oceans, which is also stripped as it is converted to a gas state! The Jet only hits the Northern Hemisphere (since we can only see the Andromeda galaxy from here), so it takes longer for life in the Southern Hemisphere to die. We pass through the jet in 20-200 years, but by that time it's too late, we have a climate like Mars!
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A simple large meteor hit at an appropriately oblique angle would cause acceleration of the earth spin. This acceleration would cause centripetal force to bleed off the atmosphere as slowly (or as quickly) as you like. It could also work to "reduce" gravity. As the atmosphere bleeds off the lower air pressure would cause the oceans to boil away, providing every effect you could want in a simple plausible manner. It adds believability in that people have lately become paranoid about meteor strikes and have started tracking everything that moves in the solar system.
Again, for simplicity, a collision in the asteroid belt could provide the impetus for the rock to hit our planet at the correct angle to impart appropriate rotational energy.
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Imagine mankind has established mining facilities on [NEO](https://en.wikipedia.org/wiki/Near-Earth_object)s
Some of them send raw ore directly to other processing stations in space, others refine on site.
All of them use a system based on cargo 'slugs' that get flung to their destination using rail guns. Near destination 'vectors' link with the cargo, slow it down and bring it in.
This is economical as only a few vectors would be needed at destination while there may be hundreds of cargoes traveling along different trajectories, paced so that reception is possible.
The problem is there are regular launches from the NEO while mining the asteroid. This means the asteroid gets an equal impulse in the opposite direction. It's mass may be billions of times bigger than the cargo but it is reducing as it gets mined and over years of exploitation and launches the orbit is going to be altered.
Now, for some asteroids that may not be a problem, the final orbit can be calculated and be safe.
For some others that may not be the case. For instance they may be at the receiving end of cargo shipments too. Or the final altered orbit may become a hazard.
**Is there another way to stabilize the orbit while keeping sending the cargoes without having to shoot an equal mass (maybe waste? but would there be enough waste? on metallic asteroids that may not be the case it seems) in the opposite direction?**
Setting:
* Our own solar system.
* Power generation is available at low price. Firing the rail gun more than once to stabilize the asteroid would not be an issue.
* Ion / chemical thrust engines such as those employed by vectors are available but much more expensive to use than rail guns.
* A slight variation in the orbit is not an issue. Vectors will adjust to it if cargo needs to be brought in. A large one happening in years of work may be.
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**You could in principle attach a solar sail to the asteroid to help stabilize the orbit, but I don't think it would be necessary.**
In the long run you aren't going to be firing all your payloads in the same direction - even if they are all going to the same destination, that destination is presumably going to be in a solar orbit different from yours, and your relative positions will vary as you move around the sun. The changes in your orbit from the launches will therefore tend to cancel out over time, and orbital changes are unlikely to be a problem anyway; the odds of hitting anything are very small, and you'll be able to predict the orbital changes in advance and take them into account when planning incoming payloads.
What's more, there is always more than one orbital route that will take your payloads from any one point in the solar system to any other; because orbits are ellipses rather than straight lines, you can choose a direct orbit that gets you there as quickly as possible, or a less direct one that will take longer (potentially even choosing to have the payload orbit the sun multiple times before reaching the target) and that gives you a great deal of flexibility regarding which direction any particular payload is fired in. So even in the unlikely event that your orbit is threatening to become a hazard you will always have the option to give it a push in a safer direction, albeit at the cost of some of your payloads arriving at their destination at a potentially less convenient time.
Planning for all of this might not be straightforward, but it should be doable. The worst case scenario is that you occasionally need to sacrifice a payload in order to make an orbital correction that can't be otherwise accommodated, but that shouldn't happen often, and probably not at all.
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Momentum is mass times velocity. You can always use arbitrarily small reaction mass provided you shoot is off at sufficiently high speed. Just use slower guns for useful cargo and high speed guns for corrections.
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> Is there another way to stabilize the orbit while keeping sending the cargos without having to shoot an equal mass in the opposite direction?
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You don't need to shoot an equal mass. Momentum is given by $m\Delta v$.
Let's say you are shooting a mass 1 with $\Delta v$ 100, you can neutralize the imparted momentum by shooting in the opposite direction a ballast mass 100 with $\Delta v$ 1. This means that the ballast won't leave the asteroid, since it won't reach escape velocity, and will also require less energy: remember that kinetic energy goes like $1/2mv^2$, so to shoot your load you would need $0.5\cdot 1 \cdot 100^2 = 5000$ while to shot your ballast you would need $0.5 \cdot 100 \cdot 1^2 = 50$.
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**move the launch site**
You can actually use the launches to correct the asteroids trajectory as much as possible. You do need to be able to move the launch site though. If you can, it can be helping you instead of destabilising.
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Yes use a fleet of large solar sail craft to transfer the material to and from any orbit you want. It will take a long time but it would be possible. Practical perhaps not but possible yes.
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The cargos could be launched at different moments of the rotation so that the overall deviation sum up to zero. You will still be losing momentum from the asteroid because of the mass loss, but I think one could in principle compute the direction of the landings and flights in order to put the asteroid on any allowed orbit.
Just to make an example. Suppose that 2 spaceships depart at the same moment and with the same amount of momentum, but at opposite sides of the asteroids and with opposite directions. Them the overall deviation will be zero.
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You also don't need an equal mass going in the opposite direction because all you need is to make sure the asteroid stays in a 'safe' orbit, rather than the 'same' orbit. It actually wouldn't surprise me if in most cases that could be accomplished even while delivering the ore to its regular destination by timing the shot. That is, sending it at a different velocity along some other-than-optimal trajectory. The ore still gets where it's needed and disaster is averted.
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You think about momentum but i think the most important issue is the gravity in this case.
I mean if we shoot the same mass to the NEO, this "shooting" action will produce a momentum but there is gravity of NEO and the Earth.
I think The Earth's gravity will be almost same in the process but NEO's gravity will change and when NEO's gravity is low, if we shoot it with anything the NEO's orbit will change with no doubt
**So i don't think there is any way to 100% stabilizing**
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Would air pressure be demonstrably greater in a subterranean city at a depth of 1 mile? Lava tubes leading into a dormant magma chamber -- this would have challenging gasses that would need to be ventilated to make it habitable, right? The consensus for the geothermal temperature gradient seems to be about 1-2 degrees F for every 100 feet of depth, so if we're starting our thermometer at the point where ground temperature mimics the average atmospheric temperature (I believe it's about 30 feet down), then I'm thinking it'll be about 75-80F at one mile down.
Air pressure below the surface adds roughly 14.7PSI per 3200feet. So it would be more compressed air, further down, but as far as I can tell, "liveable." I found [this article](https://news.stanford.edu/pr/00/000315rocks.html) that states 7500psi for every mile you dig:
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> Geologists calculate that, for every mile you dig beneath the Earth's
> surface, the temperature rises 15º F and the pressure increases
> simultaneously at a rate of about 7,300 pounds per square inch.
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So... 7300psi of air pressure at 1-mile depth? That doesn't seem right when we have active mines 2.4 miles deep.
The other part I haven't been able to research is whether air quality would be completely uninhabitable at that depth. If you're walking in a lava tube that eventually vents to the surface, how breathable would the air be with respect to pressure/oxygen levels?
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# Use mines as examples:
1 mile deep (1.6km), is *nothing* compared to some modern mines. 10 minutes drive from here there is a mine that is 3.6km deep.
We can make such mines livable, or at least tolerable, for longterm workers.
**Temperature:**
At 1.6km [depth, the temperature will be 25C](https://en.wikipedia.org/wiki/Geothermal_gradient) \* 1.6 = 40C (72f) above the average surface temperature. Hereabout the surface is about 20C, so it is an unbearably hot 60C (140f) even just 1.6km down.
Or it would be, if not for ventilation.
To keep the mine habitable for workers, they are constantly pumping groundwater out, and huge volumes of surface air in. This surface air is acceptably cool, and replaces the extreme heat expected in the mine with a mere sweltering heat. Down from 60C to about 32-35C.
**Air pressure:**
Pressure is much less of a problem, and only really manifests itself when workers move from the depths to the surface in rapid elevators. Even then it's no worse than ascending on an airliner to cruising altitude.
AT 1.6km, if the entrance is at sealevel, the [airpressure down below](https://www.mide.com/air-pressure-at-altitude-calculator) will be 1.2 atmospheres. About the same pressure as swimming at the bottom of a household pool.
**Air quality:**
Without forced ventilation you have severe heat problems, as noted above.
Even if you were to install an in-place recirculating air cooler, you would have problems. There is no oxygen source down there. If you do not get oxygen from fresh surface air, you will have to supplement it from some other source.
In addition you are surrounded by rock. This rock is continuously leaking water into the voids in it, also trace gases including such interesting ones as [Radioactive Radon](https://www.ncbi.nlm.nih.gov/books/NBK234224/). No problem if you exchange your air all the time, but if you allow it to accumulate over months it becomes a health hazard.
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It would be hot underground. [Geothermal gradient](https://en.wikipedia.org/wiki/Geothermal_gradient) indicates that on Earth, 1 mile underground would be about 40-45 C (75-80F, just as you said) hotter than on the surface. Unless your underground city lies under permafrost, that would be a definite challenge for human habitation.
The air pressure would be high (although not unbearably high). One mile deep it's going to be about 1.2 atm
Ventilation would be a challenge too. Underground city needs a lot of fresh air, and rocks around tunnels tend to release various gases, many of them harmful to humans. I don't know if it's realistic to have a livable city that deep without forced ventilation.
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I present the [Sudbury Neutrino Observatory (SNO)](https://en.wikipedia.org/wiki/Sudbury_Neutrino_Observatory), now SNOLAB, located 2100 meters down in the still operating Creighton Mine (the operating faces are currently down around 2400 meters with exploration to 3000 meters). Sudbury is 350 meters or so above sea level, so SNOLAB is about 1750 meters, or 1.1 miles, below sea level.
You will note the distinct lack of obvious challenges to people working there comfortably, so, you could ask for theoretical calculations based on assumed temperature and pressure gradients. Or just, y'know, look at it.
<https://mcdonaldinstitute.ca/wp-content/uploads/2020/07/DSCF1834_pc_ZacKenny-1176x720.jpg>
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In a sense, humanity has long been capable of transmitting interstellar messages (METI (messages to extraterrestrial civilizations) - attempts to transmit interstellar messages from humanity to probable intelligent beings outside the solar system.)
The first strong generalization sent into space was probably ... Hitler's speech.
This short television program, literally a few minutes, was broadcast in 1936 from Berlin with the opening of the Olympic Games. Although it was only received in Germany, it was the first, albeit weak, transmission from Earth. Unlike conventional radio broadcasting in the 1930s, TV signals pierced the ionosphere and went into space.
After that, the broadcast of the coronation of George VI took place in England and something else of the same kind. Truly television began only in the late 40s. And all the signals of those years are carried away from the Earth at the speed of light.
However, all of these signals are extremely weak. After passing only a couple of light years, they will fade out and it will be almost impossible to catch them, much less decipher.
Why?
The main problem with sending interstellar messages is that as the distance traveled increases, their power gradually decreases due to gradual scattering (diffraction). Imagine that you have thrown a stone into the calm surface of a lake: from the original stone the circles began to diverge in all directions, but the further they diverge, the less noticeable they become. The same thing happens with radio waves: if you calculate approximately, then twice the distance from the communication source will reduce the power of the radio waves by four times. As you can see, detecting such radio waves at a distance of several hundred light years from Earth will be a difficult task for space civilizations.
After all, as mentioned above, radio waves are not very effective for interstellar communication.
In addition, if Arecibo's message had come to us in 1913, we would not even have been able to receive it.
And here we come to the heart of the question:
What kind of the interstellar message can be received by an alien civilization with technology comparable to humanity at the end of the nineteenth century (19th century)?
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The only message the most advanced civilization at the end of 19th century could detect would have been some sort of Morse code by a very bright light source, with apparent luminosity from Earth comparable with that of a star.
At that time there were already astronomers looking at stars, and they could have spotted a "variable star" with a non regular cycle, and maybe attempt to search for a code in the variable signal.
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With pre 1900's technology on the receiving side...
No radio signal whatsoever. The energy needs to make even a single beep audible on receipt would exhaust a supernova.
No infrared or longer, no ultraviolet or shorter. There simply were not receivers for those frequencies.
No neutrino stream, gravity pulses or anything comparably high tech. There simply are no receiving mechanisms built, or even conceived yet.
That leaves visible light.
A well-focused laser light, with a slow pulsing visible to human eye would suffice.
The laser itself would need to be *both* enormous in power AND enormous in aperture (optics laws require larger aperture, to allow better focus). We are talking much bigger than planetary scale here, and exawatt levels of power, to reach even from the nearest star.
No non-laser artificial light source could even conceivably be bright enough. Even using a stream of Tsar Bomba 50MT nuclear bombs would be **totally invisible** to the human eye at just 1 light year distance.
Alternately, put a blinker between the star and the target. A star-sized, exactly positioned blinker.
Alternately, reposition the star itself. Multiple stars, actually. This is much harder than you expect. Much!
Really, for a 19th century tech receiving civilization? The easiest way would be to actually travel to them. Yes, even with all the problems of lightspeed and/or longduration interstellar travel.
The FASTEST way would be to.... wait 100-200 years, and send a radio signal using Arecibo-or-larger class transmitter.
So... realworld science is not cooperating with you!
If you want a FICTIONAL but plausible way... make something up like 'natural dilithium crystals that glow when struck by a tachyon beam from outer space". This will make a usable communications media, plausible without needing to explain the details of how and why, and allows for faster-than-lightspeed communications. Still oneway, though.
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Any large enough, optically visible structure. That was already used by Stanislaw Lem in the second story of Cyberiad.
Trurl and Clapautsius there pulled stars into a giant interstellar message, and to attract more attention, the first word was made of supergiants only.
"Two famous constructors look for a job and the appropriate reward at a court of a star monarch." (sorry, the translation is mine. Better read the original)
That message would be clearly seen and understood as a message even by Sumerians.
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There are three options I can think of, but only one (the third in my list) that doesn't rely on the sender knowing the receiver's location.
1 - the Voyager method. Throw something with data on it at them.
2 - Infrared radiation. There actually were methods to detect infrared before 1900 - Samuel Langley invented the bolometer in 1878, which could essentially be used for that purpose. Still, those were roughly prototypes. This would require something akin to a massive nuclear reactor that turns on and off close to the receiver. And the sender would probably not do this - that relies on them having a bolometer that they're watching constantly, which is unlikely.
3 - Visual light. This is more reliable than the second above, and it'd make sense if the sender didn't know where the receiver was. An object akin to a Dyson sphere/swarm with variable opacity could surround the sender's star and be toggled on and off in a pattern that transmits data. This only transmits one bit at a time, so the message would have to be fairly simple so they could decipher the meaning. Computers wouldn't exist to decipher it with.
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This is yet another "literal worldbuilding" question, as in, building worlds. Inspired, in part, by [this question](https://worldbuilding.stackexchange.com/q/27396/32642).
What if this world is a very long (effectively infinite) hollow cylindrical cavity with the diameter roughly equal to that of the Earth's orbit. The day/night cycle is generated by the following arrangement: multiple suns falling through the center of the cylinder. The distance between the suns and their speed relative to the world surface are adjusted to generate approximately 24 hours cycle, just like on Earth.
[](https://i.stack.imgur.com/qkLmt.png)
While there are several issues with this idea, most importantly huge tidal waves generated by the gravity of the suns, and the fact that empty space inside will be quickly filled with matter both from the suns and the cylinder itself, let's ignore them for now.
This question is simple enough:
* What would the sky at some point on the surface look like during day and night, as well as dawn and twilight? By that I mean, how would the suns move, how would the lighting change, etc. How different would it be from our own experiences?
I would like the answer based on actual geometry and optics. I have poor spatial imagination which is why I need some help with that :)
The suns should be spaced enough so that the night is mostly dark, though of course we can't avoid some light, since there's no horizon. The size and the energy output of the suns can be modified as well, because the cylinder would collect all the energy, radiation and solar wind, which could be too much.
Optionally, I would also like to see what other problems arise with this arrangement, though I could ask a separate question for that.
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There's a similar "tube world" arrangement in [this question](https://worldbuilding.stackexchange.com/q/30933/32642), but it's a little too complicated and can't be used to answer my question.
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Just to clarify: I want this world to support flora and fauna as close to Earth-like (temperate climate) as possible.
[Answer]
Let me start with the additional problems that arise:
* The trajectory of the suns is not stable. If they are slightly off-center, gravity will pull them towards the side of the cylinder that they're closer to, analogous to the [ringworld stability issue](https://physics.stackexchange.com/questions/41254/why-is-larry-nivens-ringworld-unstable). You could work around this by using stellar engines of some sort to keep the stars centered, or making the cylinder a tiny bit flexible and using motors to change its shape dynamically....
* There is nowhere for the heat that is generated by fusion in the cores of the suns to escape, apart from conduction through the crust towards outside space. You could work around this by putting large holes in your cylinder through which outside space is visible, by making your crust very thin (on the order of meters), or by making it very conductive (by adding an active cooling system that pumps heat outside). This oversimplified illustration shows the relevant mechanisms that keep earth's surface at its equilibrium temperature, and how the inside of your cylinder would heat to over 2 million Kelvins without any countermeasures:
[](https://i.stack.imgur.com/N8f2m.png)
Now, to your actual question.
The only relevant parameter is the distance between the suns, in AU. The speed at which they move follows automatically from your requirement that one sun should pass every 24 hours. It will be rather high, though :)
You will, of course, always see an infinite number of suns, but most of them will be very dim and very close to the horizon. Here's what the sky will look like, with the apparent brightness of the suns (= the area they occupy in the sky) written next to the dots.
suns spaced at 1AU:
[](https://i.stack.imgur.com/IasyE.png)
suns spaced at 20AU:
[](https://i.stack.imgur.com/yiOHa.png)
To calculate the total illumination, some math is required. You need to calculate the [infinite sum of the contributions of each sun](https://www.wolframalpha.com/input/?i=sigma%28x+%3D+-inf+to+%2Binf%29+of+1%2F%281%2B%28d*%28x%2Bo%29%29**2%29). In this formula, `d` is the distance between the suns in AU, and `o` is the offset from mid-day, where `o=0` means mid-day, and `o=1` means mid-day tomorrow.
This gives the following equation for the momentary strength of illumination (assuming that the power output of one sun at 1AU distance is 1):
`-(π sinh((2 π)/d))/(d (cos(2 o π) - cosh((2 π)/d)))`
To find your preferred value of `d`, just plot this formula for various values.
Here's a quick python snippet that does exactly that, since I couldn't get nice plots out of Wolfram Alpha:
```
#!/usr/bin/env python3
from argparse import ArgumentParser
from math import sqrt, sinh, cos, cosh, pi
import numpy
from matplotlib import pyplot as plt
cli = ArgumentParser()
cli.add_argument('--distance', type=float, default=1)
cli.add_argument('--average-illumination', type=float, default=0.25)
args = cli.parse_args()
power = 0.31831 * args.average_illumination * args.distance
hours = numpy.arange(0, 24, 1/60)
illuminations = []
for hour in hours:
offset = hour / 24 - 0.5
illuminations.append(
-power * pi * sinh((2 * pi)/args.distance) /
(args.distance * (cos(2 * offset * pi) - cosh((2 * pi)/args.distance)))
)
fig = plt.figure()
ax = fig.add_subplot(1, 1, 1)
ax.set_xticks(range(25))
ax.set_xlim(0, 24)
ax.set_yscale('log')
ax.grid()
ax.plot(hours, illuminations)
ax.set_title(f'spacing: {args.distance} AU, '
f'luminosity: {power} L0, '
f'min: {min(illuminations):.5g}, '
f'max: {max(illuminations):.5g}')
# from https://en.wikipedia.org/wiki/Lux#Illuminance
ax.annotate("moonless clear sky with airglow", (0.5, 0.002/100e3))
ax.annotate("full moonlight", (0.5, 0.3/100e3))
ax.annotate("dark limit of civil twilight", (0.5, 3.4/100e3))
ax.annotate("family living room lighting", (0.5, 50/100e3))
ax.annotate("very dark overcast day", (0.5, 100/100e3))
ax.annotate("sunrise or sunset on clear day", (0.5, 500/100e3))
ax.annotate("overcast day", (0.5, 1000/100e3))
ax.annotate("indirect daylight", (0.5, 10000/100e3))
ax.annotate("full daylight", (0.5, 1))
# from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5718773/
ax.annotate("survivable for minutes in firefighter's clothing", (0.5, 2))
ax.annotate("survivable in aluminized clothing", (0.5, 4))
plt.show()
```
And plots for some distances:
[](https://i.stack.imgur.com/JGib0.png)
[](https://i.stack.imgur.com/8eXj4.png)
[](https://i.stack.imgur.com/VeeAE.png)
[](https://i.stack.imgur.com/Rlv3O.png)
[](https://i.stack.imgur.com/H3oNs.png)
Distances above 180AU are impossible because then the suns would be moving faster than the speed of light; decreasing the cylinder diameter would solve this.
In these cases, I try to maintain the same average heat flux that is experienced on earth, to allow meaningful photosynthesis. You can see that if you want proper darkness at night, there will be short hard bursts of heat which will only be survivable in underground bunkers.
If you're willing to reduce the average heat flux to say 1% of that experienced on earth, that is, around 3 W/m², you can achieve this:
[](https://i.stack.imgur.com/CwtlA.png)
With only 1% of the power flux, you will only have 1% of the photosynthesis, solar power, wind power, fossil fuel formation etc, so your land will generally only support 1% of earth's population density. Advanced civilizations may however harvest tidal power from the tidal accelerations of the passing stars, and "reverse geothermal" power from the heat flux through the crust. This heat flux will be far stronger than on earth.
Other interesting effects which I haven't considered:
* the light of very-far-away suns will travel a long path through the atmosphere; this means that their light will be scattered and they won't be actually visible properly. It's just like the sun gets distorted and reddish during sunset, only the effect will be literally infinitely stronger.
* there will be effects from special relativity: the light of approaching stars is blue-shifted, and their power output will appear different since time passes at a different rate in the star's cores.
* since the light of oncoming stars will be blue-shifted and the light of receding stars will be red-shifted, there will be a constant radiation pressure in the direction in which the stars are moving. this will accelerate the atmosphere, causing westward wind. I'm not sure how to calculate the strength, though. Solar wind particles will have a similar effect.
There's another great way in which you could achieve day and night, though: Your population could live in a narrow valley such that only suns that are above 30-or-so degrees over the horizon are actually visible. There will still be atmospheric scattering, but some tinkering with the atmospheric composition could fix that.
[Answer]
## First pass: the geometry is simple
In the first pass, we disregard the cylindrical shape of the world, and we assume that the light sources are in free space, moving against a black backdrop.
Let's assume that:
1. Each of the light sources moving through the tube produces the same amount of light as our own Sun; and
2. At midnight we want to have the same illumination as that produced by a full Moon.
Good to know:
* The illumination produced by a full Moon (around 0.1 to 0.3 lux) is between 400,000 and 1,000,000 times weaker than the illumination produced by the Sun at noon (around 100,000 lux). (That's 19 to 20 exposure steps, in photographic terms.)
* The illumination produced by a light source is inversely proportional to the square of the distance between the light source and the illuminated object.
With these assumptions, it follows that:
* For the illumination produced by one of those moving light sources to decrease 800,000 to 2,000,000 times (the doubling is because we are illuminated by the *next* moving light source) it must move to a distance of 900 to 1400 [astronomical units](https://en.wikipedia.org/wiki/Astronomical_unit) (= the radius of the orbit of the Earth, i.e., the radius of the cylinder assumed by the question).
* The distance between two consecutive light sources will then be 1,800 to 2,800 astronomical units.
```
2000 a.u.
<−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−>
1000 a.u.
<−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−>
\ | / Light source \ | /
··· --(•)-- ····················································· --(•)-- ···
<<< / | \ <<< Movement ^ / | \
|
|
| 1 a.u.
○ |
Observer /|\ |
Ground / \ v
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
////////////////////////////////////////////////////////////////////////////
```
## What about the *speed* of those light sources?
Hmm, that's a bummer. Light travels a distance of one astronomical unit in 8 minutes 20 seconds, which means that in one hour light travels a distance of 7.2 astronomical units, and in 12 hours it travels 86.4 astronomical units. Since the moving light sources need to travel about 1,000 astronomical units in 12 hours, it follows that they must move about 11.6 times faster than light.
Clearly, Einsteinian relativity doesn't apply in this world.
## What the observer sees
At noon, the observer sees the light source overhead bathing the landscape in a sea of light, very very similar to what we see at noon.
At midnight, the observer sees a dark sky, with two very luminous stars at opposing points near the horizon.
Unlike on Earth, where the difference between daytime and nighttime is clear as day and night, on this world illumination varies gradually from full day to full night, with no clear separation between them. *Most of the time* it will be quite dark:
* Illumination on a heavily clouded day is about 5 lux, or about 20,000 times lower than the illumination at noon on a clear day. Taking this as the threshold between day and twilight, the light source would have to be about 140 astronomical units distant, or one sixth of the 1,000 astronomical units which we considered midnight.
* Taking the threshold between twilight and night to be 1 lux, that corresponds to a distance of some 320 astronomical units between the observer and the light source, or about 1/3 of the 1,000 astronomical units which we considered midnight.
* All in all, in each 24 hours cycle, the observer will see about 4 hours daytime, about 16 hours night time, about 2 hours dawn and 2 hours twilight.
## Second pass: but, but, but, but...
In the first pass we disregarded the cylindrical shape of the world, and we assumed that the light sources move against a black backdrop.
Now, that is perfectly fine as regards visible light. Assuming that the world has about the same albedo as Earth, the cylindrical shape of the world won't make a great difference. Yes, at noon there would be just a little more light than what the calculations in the first pass would suggest, etc. But the difference is utterly negligible, even for the keenest photographer.
The problem is not visible light, the problem is infrared light.
Earth likes very much to remain at constant temperature; see the great worldwide wailing at the prospect of increasing the average temperature by a measly one degree centigrade over a century.
Earth does this by radiating back into space all the energy it receives from the Sun. While the energy Earth receives from the Sun is mostly in the visible spectrum, the energy radiated by Earth is mostly in the infrared range.
And here comes the catch: those infinitely many sources of light will make the inner surface of the cylinder as hot as the Sun in a very short time. (Short time, geologically speaking, of course.)
Let's see what happens with a random square meter of ground in this cylindrical world:
1. During daytime, that square meter of ground is warmed up by the visible light falling on it.
2. At night, on our spherical Earth, that square meter of ground emits the heat in the form of infrared light. Most of the infrared energy is lost into outer space; some of it warms the air a little, and is then re-emitted by the air in the form of far infrared. Eventually, all the thermal energy dissipated by the square meter of ground as infrared radiation is lost into outer space.
3. But on this cylindrical world *there is no outer space*. All the energy ever received by that square meter of ground *remains in the system forever*. At night, the square meter of ground emits infrared light, but it does not help, because it absorbs the same amount of infrared light emitted by all those other square meters of land elsewhere on the inner surface of the cylinder.
4. Every 24 hours more and more energy is added to the square meter of ground, and it has nowhere to go except to warm up other square meters of ground. In a short time, every square meter of ground on the inner surface of the cylinder will be in thermal equilibrium with the sources of energy.
[Answer]
If the tube rotated to produce "gravity", that gravity would pull down to the outside of the tube. So people would look up at the suns passing by.
If the suns have the mass of Sol, the Sun, they will eventually swell into red giants and greatly increase their luminosity after about ten billion years. That will cook the inside of the cylinder and maybe evaporate it into gas escaping into space. Then the red giant stars would turn in to white dwarfs after shedding significant amounts of mass. The stellar mass loss would produced strong solar winds which might push apart the cylinder, destroying it and would certainly devastate the already devastated surface.
One way to avoid it would be to make the cylinder much narrower and make the suns correspondingly dimmer than the Sun to adjust for the closer distance to the surface of the cylinder. Those dimmer stars will have lower mass than the Sun and will have steady luminosity for a much longer length of time, hundreds of billions or maybe trillions of years depending on their mass.
Or the suns could be stars which were already white dwarfs and which would be very, very gradually dimming down to black dwarfs. That would also take a very long time, perhaps trillions of years.
Or maybe you could make the suns giant lamps moving down the cylinder. They would have giant fusion generators to generate the power for the giant lamps used to illuminate the inside surface of the cylinder.
Of course maybe you don't care abut whether your setting will last for one billion years, ten billion years, a hundred billion years, or a trillion years.
Have you thought about what material your world would be made out of? You might need some hyopthetical fictional super strong materials.
Have you read Larry Niven's article "Bigger than Worlds"?
<https://en.wikipedia.org/wiki/Bigger_Than_Worlds>[1](https://en.wikipedia.org/wiki/Bigger_Than_Worlds)
<http://www.isfdb.org/cgi-bin/title.cgi?133302>[2](http://www.isfdb.org/cgi-bin/title.cgi?133302)
[Answer]
I can talk about the math in the abstract but since we have no figures here, it will be rather abstract.
The two factors will be:
1. Absolute magnitude of the suns
2. Distance from the sun to the surface when the sun is directly overhead.
The suns' light falls off by the square of the distance. This will determine its relative magnitude, which will increase until it passes over ahead, and decrease as it goes away. This will have to factor in the overhead distance. If the sun passes 3 (units) overhead, when it reaches 4 (units) farther away from that point, it will be only 5 (units) away from the person on the ground. Hence, if we measure give the brilliance of the sun at directly overhead a measurement of 100, it will be 36 when 5 units away -- 5 divided by 3, result squared, used to divide 100.
If it were alone, the new sun will first appear in the sky when the relative magnitude rises to a high enough level that a human eye can see it against the ambient light. The human eye is capable of seeing quite dim objects, so the actual factor is more likely to be that the prior sun is still putting out enough light to drown it out. (The luminosity difference between the Sun and the dimmest stars visible to the naked eye on a clear night past twilight and with no ambient light sources, either the moon or artificial, is about 10 to the 14th power.)
There would be no "night" vs. "day" You would have the sun overhead in its full brilliance, and then it would move off, slowly dimming, until it was dim enough that the new sun could be seen, and then it would continue to dim as the new sun brightened. The peak darkness would be the point at which the two suns were equal in brilliance. Then one would brighten as the other faded.
Distance from the surface will be important because that will decrease relative magnitude in a way that is not entirely dependent on the motion. There could be some very dark periods but the variation in light and dark would be continuous.
] |
[Question]
[
In my world there is a metal commonly associated with enhanced magical properties. However as a balancing system I don't want this metal to be combined or forged in any way. The technology level is around Gregorian year 0, but they do have magic available so they could creatively get around minor problems like heat requirement etc. Is there a metal that could fill the following properties (in this era), or do I need to invent one entirely?
* Occurs naturally in shards/nuggets no larger than an inch.
* Cannot be molten down at this technology level.
* Cannot be forged together/fused at this technology level.
* Is as rare as Gold.
* Does not occur in large deposits (a few bits at a time max).
The aim is to develop a magical process that eventually *can* reforge this metal into a weapon, but this shouldn't be possible with their regular technology. So bonus points if it is workable with modern technologies.
[Answer]
Native nuggets of platinum/iridium alloys exist (*always* found as an alloy). They have a melting point beyond any temperature attainable with pre-17th century technology (a steel furnace won't melt them), can't be joined into larger pieces (platinum is more ductile even than gold, but less malleable, and can't be cold welded), and are even more chemically noble than gold.
In our world, these nuggets are much rarer than gold nuggets, but they form the same way, so a minor (hand-waved) change in crustal chemistry and geology could lead to veins of platinum/iridium resembling the vein of gold/silver/copper alloys found in rock.
[Answer]
Your best approaches are things like titanium or aluminium where, rather than anything resembling a pure ore, they're found in oxides requiring chemical processes of moderate complexity to extract.
That gives you the plot space for advanced magic/alchemy needing to understand exactly what's going on before they can get the pure metal out.
You'll probably then want some excuse to alloy with iron anyway, rather than using the pure metal.
[Answer]
I'd say, your best bet would be something like chromium.
* It is relatively rare (10 known places on our Earth where you can find decent quantities.
* To aquire pure chromium you need a complicated chemical process
* In it's pure form chromium is forgable
Bonus:
Chromium occures, amonst others, in a specific type of iron ore, although in varying percentages. Means you would have a source of magic metal with differing power levels.
[Answer]
Gold is useless for weapons because it is too soft. Your metal also can be too soft to be useful for weapons. On the other hand, silicon is too brittle so again, hardly can be worked and used.
If you want a random metal to be too brittle, which prevents working it and using it as a weapon just make it having impurities and/or crystal defects. When those removed the metal becomes more useful.
] |
[Question]
[
The **Dyson Swarm** is common in sci fi as an energy source, and sometimes also as a powerful weapon. As it is commonly understood, it harnesses the energy of the sun, which stores a vast amount of energy. A Dyson Swarm is necessary for any civilization to be deemed Level I or II on the Kardashev Scale.
However, I quickly realized a small flaw in this design: it is not stated how the energy from the sun could be transferred to the planets whose civilizations need it, especially our Earth.
I believe that this issue should be resolved for the concept to truly work. Therefore, I ask, if Dyson Swarms could even be created, how would the stored thermal and light energy be transferred to respective planets?
PS: *Thanks for people pointing out that Dyson Spheres are habitats, not just energy collectors for planets.*
[Answer]
# EM Radiation
1. Collect energy
2. Use energy to shoot lasers towards Earth
3. Use dish antennas to catch laser energy
4. ???
5. Profit
Don't believe me just because I'm saying this. [NASA and JAXA have made some baby steps in that direction](https://en.wikipedia.org/wiki/Space-based_solar_power#History). And anyway any Dyson sphere that sends its energy elsewhere is based on this idea.
Also, don't worry about [dying from being shot with space lasers](https://worldbuilding.stackexchange.com/a/108341/21222). The wiki article linked in the paragraph above says:
>
> Contrary to appearances of SBSP in popular novels and video games, most designs propose beam energy densities that are not harmful if human beings were to be inadvertently exposed, such as if a transmitting satellite's beam were to wander off-course.
>
>
>
[Answer]
**You've missed the whole point of a dyson sphere**
There are no planets to transfer the energy to. A dyson sphere would have a living space equivalent to around 550,000,000 times the surface of the Earth.
>
> The variant of the Dyson sphere most often depicted in fiction is the "Dyson shell": a uniform solid shell of matter around the star. Such a structure would completely alter the emissions of the central star, and would intercept 100% of the star's energy output. Such a structure would also provide an immense surface that many envision would be used for habitation, if the surface could be made habitable.
>
>
>
See [Dyson Sphere](https://en.wikipedia.org/wiki/Dyson_sphere)
Virtually every last piece of mass in the solar system would be required to build the sphere so Earth, Mars, Venus and even Jupiter would be mined, refined and used to build the sphere. Quite possibly we'd have to raid nearby solar systems for more materials.
Finally you wouldn't want to be outside anyway as there is no longer a sun for the planet.
[Answer]
**Synthesize antimatter in space.**
Transmission of power is near future SF and well and good; yes, yes. Goldeneye and all. Tesla.
Another option would be to lock the energy into a portable form and bring chunks of it home. This is akin to liquefied natural gas or other concentrated energy sources that are more portable and less dangerous for being concentrated.
The most concentrated fuel would be antimatter. Space is a good place to be fooling around with antimatter because of the go boom prospects. Operating according to E=mc2, raw solar energy is turned into antimatter. Antimatter pellets in their magnetic bottles are stored in space then ferried down to earth on an as needed basis to power generators.
[Answer]
[](https://i.stack.imgur.com/not2e.jpg)You do not need wires to transfer power. See this article: <https://en.wikipedia.org/wiki/Wireless_power_transfer>
The interesting thing about transmitting power from space is there is no nighttime down-time. The power station just needs an orbit where it can transmit to the groundstation as the planet spins.
The red circles are space based power zones for my space game.
[Answer]
**A simple one would be to use an orbiting swarm of mirrors.**
The angle of the mirrors could be adjusted to reflect 'natural' sunlight towards earth, where it could be captured for use.
This would be the simplest method, as the satellites would be relatively easy to manufacture so you could mass produce them. They would also be simple to operate and have little to no maintenance - if it was a mirror all you need is a way for it to rotate (perhaps a gyroscope) to reflect light.
An onboard computer (or centralised computer if you don't want complexity in each one) could calculate the optimum angle to maintain altitude, positioning and trajectory to ensure the swarm is stable. The reflection of the sunlight would change the satellites trajectory, and balanced with gravitation forces, and thus needs to be coordinated.
If the radius of the swarm is roughly the same orbital distance to Earth, it is conceivable that almost all of the sunlight from the Sun could be diverted to Earth. If they are closer to the Sun you may need to get complex and reflect light of other satellites to then reflect it onward to Earth.
This naked sunlight would be then converted to useful energy at a focal point either on Earth (which would likely not be good for Earth) or near Earth (perhaps L1) where it could superheat mass to generate power, fuse atoms or other methods of power generation from extreme concentrated heat and radiation.
[Answer]
As far as I can find, no one has taken on the concept that you can't actually beam all that energy to the earth without turning the earth into an ant under a magnifying glass. Harnessing wind or solar power doesn't change the energy on earth, we're just moving it to motors and microprocessors where its heat moves back to the atmosphere. But if you somehow beamed all the energy of the sun to the earth, we would also need a corresponding method to gather and beam all the excess heat back into space so we wouln't burn the planet to a crisp.
I find it much more likely that we would be harvesting the energy from the earth's core well before we tried to gather it offworld from the sun.
] |
[Question]
[
So for a thought experiment I came up with the idea of a species that uses wheels for locomotion, sort of inspired by a species shown in His Dark Materials. Under what circumstances would such a species develop, and what would they look like? And more importantly, how would a creature with wheels work physiologically?
[Answer]
When designing a wheeled animal, there are three problems you must overcome:
* How to have a wheel as a body part without it being separate from the body.
* How to propel oneself
* Smooth roads; if you spend energy making them, that can be exploited by peers and is thus not a viable evolutionary solution.
*His Dark Materials* tackles all of those problems excellently with its mulefa race.
[](https://i.stack.imgur.com/H3gu0.jpg)
Rather than having their wheels as an organ, the mulefa have entered a symbiosis with the seedpods of local plants. These disc-shaped seed pods fit onto spurs on their legs, allowing the mulefa to travel speedily. Meanwhile, the grinding against the ground cracks open the pods, spreading the plants' seeds.
The mulefa evolved very differently from the real world's chordates; rather than a spine, they have a diamond-shaped skeleton with legs on each corner. While the back and front legs are used for attaching the seedpods two, the middle pair of legs serve as limbs to push when the rolling slows down.
Lastly; *The Amber Spyglass*' parallel Earth features formations of volcanic rock, smooth strands of basalt. These serve as perfectly good roads and are evolutionarily viable because the mulefa expend no energy in constructing them.
---
>
> Under what circumstances would such a species develop, and what would
> they look like?
>
>
>
I imagine that your creatures' ancestors would start out by learning to roll on the already disc-shaped seed pods (many real seed pods are disc-shaped), consequently cracking them open on the rock and unknowingly helping the plants spread their offspring.
The creatures would get further on more round, smooth pods, so the plants which bore rounder smoother ones would have a selective advantage (since, the further the creatures ride the pods, the more likely they are to open).
This trend of specialization would continue until the seedpods were very well-designed
for rolling and the animals for utilizing them.
>
> And more importantly, how would a creature with wheels work
> physiologically?
>
>
>
They would probably be adapted for speed, and if they had those diamond-shaped skeletons their internal organs would probably be configured differently. Other than that, I cannot foresee any major physiological considerations, except those which you are free to make up yourself.
[Answer]
I'd posit an alternative scenario: even here on Earth we find cases of parallel specialisation in which two species effectively co-evolve - we refer to them as symbionts. Mostly, these tend to be cases in which the symbiont is microscopic relative to the host (think gut boita, skin biota et al) but we do see macroscopic, macros-fauna examples - birds (Egyptian Plover) which clean crocodile teeth, fish which clean parasites and dead skin from larger fish's skin, and so on.
Let's imagine a **species pair** which gets this done.
How about we take one of the elements of Morris the Cat's answer - and posit a critter whose *whole body* is wheel-like, but in our case when actively curled up like a pangolin or armadillo, and then posit a chassis critter which then cares for (feeds, cleans, protects) four wheelie critters, and whose terminal claws are hook-shaped (thank to Philip Pullman) but whose highly-motile lips (giraffes, horses) allow for a wide range of cleaning activities... let's further posit that the wheelie critters are typically slow-moving and heavily-armoured (therefore don't travel far) and so their selective pressure advantage to this is being widely spread and fed, which allows them to structurally support the weight of their host. The host evolved from an arborial species which brachiated quickly under branches, hence the long back-curved hooked claws (sloth-like but faster and more flexible) and so they too gain huge travel advantages from this symbiosis.
If you're not stuck with Earth-based skeletal systems, go for six-limbed to distribute the weight between more of the wheelie critters.
I think this could work - the wheelies are then also almost pets - companionable, cared-for, and of course, in situations of total extremis, as a last ditch, they are edible.
[Answer]
A creature with biological wheels is pretty unlikely to evolve naturally, as there are few (if any) reasons why a half-evolved wheel would outperform a half-evolved leg. However, a creature that evolved to behave like a wheel is definitely reasonable: For their origins in the shallow reefs of your world this hypothetical creature, the 'armawheelo', evolved a unique defense mechanism to dissuade predators and travel in comfort.
---
The armawheelo's back skin consisted of [tough, slippery, streamlined scales](https://en.wikipedia.org/wiki/Scute), and when a predator approached not only would [curl into a ball](https://en.wikipedia.org/wiki/Armadillo#Defensive_behavior) to protect its vulnerable underbelly, but it would use it's flippers to spin itself as fast as it could. Predators struggled to get a grip on the spinning armawheelos, giving them enough time to bolt into the safety of sharp coral and rock where the armawheelo made its home.
As the armawheelos began to move onto land, their curling and spinning found a new use. The cliffs beside their watery homes were bountiful, but dangerous. To escape predators, the armawheelos would curl into their trademark ball and use their flippers to propel themselves down the cliffs, rolling and bouncing to safety. The armawheelos who could predict the smoothest, safest slopes back to the water had the best chance of escape.
As the armawheelos with the best understanding of slopes moved from their coastal origins and onto the rolling plains, they finally find a purely locomotive use for their curling prowess. They waddle to the top of the nearest hill, scout out a promising area for the best grubs around, and roll their way towards it in a way that's faster and less tiring on their stubby legs. They need not fear birds who cannot pierce their scaly rolling hide, and their propensity for careful observation of hill and dale helps them avoid any would-be predator.
[Answer]
As it happens, this has been done before. A species in [David Brin's Uplift](https://en.wikipedia.org/wiki/List_of_Uplift_Universe_species) series of novels uses wheels for locomotion.
>
> G'Kek (ab-Drooli) - The first of seven races to illegally settle on
> the fallow planet Jijo, the G'Kek have since become extinct elsewhere
> in the galaxy, due to a campaign of persecution which the Jijoan
> exiles sought to escape. Physically, they are wheeled creatures with
> magnetically-driven axles and a pair of short "pusher" legs,
> possessing a compact trunk with two arms ending in weak, feathery
> hands, and topped by four highly sensitive eyes on stalks. Most of
> their emotive expression is produced by these eyestalks; twining two
> stalks together is equivalent to a shrug, while having all four eyes
> stare into each other connotes introspection.
>
>
>
The critical factor here relevant to your question is that this didn't evolve naturally. The G'kek's wheeled locomotion was deliberately designed into them by a more advanced race. There really isn't any realistic way that a wheel/axle structure could evolve naturally, so your species would have to be at least partially artificially evolved by someone else.
The only alternative I can think of would be for the species entire BODY to be the 'wheel' and they just roll around. You could have manipulator limbs and sensory organs and so forth attached to the 'hub', but they would have to operate like an owl's neck does, once every rotation of the 'wheel' they'd have to spin a turn in the opposite direction to avoid overstressing the joint where they attach.
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Expanding from @Morris The Cat answer, I think the best idea is a creature that can roll on its entire body.
My idea is a kind of shellfish, who has an almost spherical shell. They can breath for a small time out of water and protrude the head and the tentacles from an opening in the shell, but can also completely seal themselves inside it.
They live near the coast, in a place with high sloping rocky reefs and strong tides. When the tide rises, they reach the top of the reefs, maybe because they've adapted to integrate their diet with some kind of vegetables the live over there. But at some point, during the low tide it can become too dry for them to survive (or staying there too long would attract birds and be dangerous), so they must quickly reach the sea. The quickest to reach are the most likely to survive.
So, in the millennia, some shellfish started to roll on their shell along the sloped reefs to reach the sea. In even longer times, it is possible to forecast that they would learn to move also on flat ground, developing some methods to give themslves momentum and direction. For instance they could give themslves impetus using the tentacles (like somebody giving himself impetus on a scooter), or - even better - contracting their muscles to continuously move ahead their center of gravity.
Probably they would move only for short paths (because they have no way to check direction while rolling), or could evolve small holes in their shell, under which they have light-sensing tissue or rudimental eyes.
This could be possible even with radial-simmetry animals, like starfishes, which could roll on their sides (think of their arms as the radia of the wheel). They have more than five arms (better rolling this way), and moving them they can gain momentum and steer. They could see the direction by having eyes (or less fragile light sensing organs) on the point of their arms, so that at every time at least one eye is looking ahead.
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Despite what others have suggested, I think that wheel/axles could evolve naturally. Many systems that we have may have originally evolved for one reason and then was co-opted for another. It has been suggested that [bones first evolved as a way to control calcium concentrations](https://doi.org/10.2307/2409087), but have since been used as a structural element.
Our creature first develops several bony shield-like appendages as a defense against predators. These appendages develop a smooth round form, which makes it hard for its predators to grab onto, which have sharp claws. The creature begins to secrete an oily substance around the shell that makes it even harder to grab onto. This appendage protects it against most predators, but the shield is heavy and makes the creature slow because it has to lift the shield or drag it. The creature than evolves a mechanism to release the shell and run away, which can later regrow. The shell grows much like an antler—it is immobile and covered in living tissue during a part of the season, but becomes dead and detachable during the rest of the year.
The creature lives on a planet where the surface becomes molten during the summer (this is the season where the creature hibernates in deep caves and regrows its shields). During the rest of the year, the surface of the planet is quite flat and smooth. Hence, we have all the ingredients for the creature to evolve wheels. One of these creatures is born with shields that don't detach well, but start to spin along the ground on the joint (using the lubrication the creature is already producing). This allows the creature to run around more quickly without lifting or dragging its shields. This creature's offspring very quickly evolve appendages that act less and less like shields and more and more like wheels.
Now the creature runs on legs and uses the wheels for more efficient travel on the flat surface of the planet (like a skateboard). Subsequently, the creature develops a week electrical system that allows it to apply force to the wheels. You see, the creature is able to deposit metal on the wheels (this isn't too crazy since [bacteria form metal nanoparticles](https://doi.org/10.1016/j.colsurfb.2010.02.007)). Maybe this metal strengthened the shields or wheels. This metal develops by chance has a coil-like structure that allows it to respond to magnetic pulses produced by electric currents in the nervous system in axle. This coil evolves toward a efficient [AC induction motor](https://en.wikipedia.org/wiki/Induction_motor) design, allowing the wheels to be directly driven. The legs, now mostly being dead weight, become smaller and smaller until the creature drives on motorized legs alone.
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I have for kicks designed a biological wheels system in class once. The problem with any of these wheel systems is that it needs to evolve rather than be engineered. Somewhere during that evolution you have half a wheel. How useful is it? How does half a wheel that probably cant even turn, start becomming a full wheel that can? How does the bloodsupply and nervous system evolve?
One thing I did run up against is that even my designed bio-wheels would have a limited time they can function. During rotation bloodsupply will be greatly limited to the wheel part. You could offset most movement to the "hip" where the wheel it attached and basically allow several appandages to turn the wheel, but the skin, bone and flesh will eventually need blood again. Operations on your arms can happen while all the blood is out and it takes several hours before permanent damage happens so it could work for most trips.
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I think that the creature being the ball/wheel is the most plausible. Expespecially considering that we have at least one that already does. The three banded armadillo is the only animal I can think of but it wouldn't be a big jump for a armadillo-like creature to go traveling around rolled up. Especially if it's mostly used for hills. It would be very energy efficient and eventually it would learn the best way to roll. It will eventually possibly learn and/or adapt a way to shift the center of mass so that it can roll longer
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[
So I have a planet with multiple species on it. My planet is tidally locked. I know it is generally thought a tidally locked planet couldn't harbor life because of the extreme temperatures, but my argument is that it is theoretically possible if the planet has a thick enough atmosphere, which helps with cooling, and if there is steady airflow from light side to dark side. This does cause very extreme weather, especially around the area where it goes from light to dark, but still, it keeps the temperatures survivable most places on the planet, except the spots closest to and furthest away from the star.
But here's my question. I am assuming on a planet like this, circadian rhythms would not have evolved since there is no day night cycle, and therefore species would not sleep, at least not in the way we do. The planet is at a tilt, and therefore some latitudes do have daylight during summer and night during winter, so in those places I can see hibernation being a thing. But otherwise, I don't think they would sleep.
So my question is what could replace sleep as a restorative process for their bodies? Entropy would still cause their cells/neurons to degenerate, and so I imagine they would still need some kind of regular, restorative process to keep them functioning. What could this be? How exactly does sleep help restore our own brains? If I understood how that works, I might be able to come up with a reasonable process to replace it.
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>
> So my question is what could replace sleep as a restorative process for their bodies? Entropy would still cause their cells/neurons to degenerate, and so I imagine they would still need some kind of regular, restorative process to keep them functioning.
>
>
>
The thing is, *we don't actually know that sleep does this for **us***. It's a popular theory, but we don't actually *know*. "Restoring neurons" sounds great, but no one has shown that that's what sleep does. There's [research about strengthening connections and cleaning away waste](https://www.bbc.com/news/science-environment-32606341), but, again, none of it is really conclusive.
Check [this out](https://www.independent.co.uk/life-style/health-and-families/features/why-do-we-sleep-10358539.html):
>
> Sleep scientist William Dement, who co-discovered REM sleep and helped found the Stanford Center for Sleep Sciences and Medicine, said in 2010, after more than 50 years studying sleep, that: "**As far as we know, the only reason we need to sleep that is really, really solid is because we get sleepy.**" Sleep is one of the greatest mysteries in biology. We have no idea why we need to sleep, or why it's so debilitating if we don't. Lots of hypotheses, but no conclusive answer just yet.
>
>
>
We definitely know that humans and other mammals need sleep to live, so *something* is going on. So, eh, maybe creatures in your world sleep, maybe in a pattern unrelated to a day/night cycle. Or maybe they just have other brain structures that do ... whatever things sleep actually *does* ... on a *continual* basis.
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**Die, and be reborn.**
In general, if you have stuff, you can maintain what you have. Or you can throw it out when it is worn and get new. Our bodies do both. Epithelial cells (like skin) fulfills its task and then dies and is sloughed. Blood cells live their lives and then die and are recycled.
Neurons are not recycled. They are long lived, and so are maintained. Presumably sleep is part of this maintenance. But there is no particular reason for them not to die and be replaced like other cells in the body. The dying neuron would hand off its information to its replacement before it died. Your organisms could do this periodically, like a snake shedding its skin. The in-between period offers narrative potential.
Re the bigger questions of sleep - interesting for a fiction but these big, unresolved questions. There is a question of memory - how it is stored and where. Is sleep necessary for such things? Why do we sleep? Why does every animal sleep? Would it not be evolutionarily advantageous to not have to sleep? These are open questions and the subject of ongoing research. You could riff off of these for your world - your Sleepless Ones might have advantages and disadvantages compared to sleepy Earth creatures.
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**Half sleep.**
Dolphins sleep one half of the brain at a time. The other half tends to basic functions, like going up to get air,
<https://www.livescience.com/44822-how-do-dolphins-sleep.html>
>
> Instead, these animals undergo an unusual form of sleep called
> "unihemispheric slow-wave sleep." Also known as deep sleep, slow-wave
> sleep is a type of sleep thought to help the brain consolidate new
> memories and recover from its daily activities.
>
>
> When it's time to rest, a dolphin will shut down only one hemisphere
> of its brain, and close the opposite eye (the left eye will be closed
> when the right half of the brain sleeps, and vice versa). During this
> time, the other half of the brain monitors what's going in the
> environment and controls breathing functions.
>
>
>
In your world of perpetual day, if you want to have some kind of sleep you could adapt something like this. It would make for an interesting story to think about a human that slept like this - maybe your aliens are of human stock originally and have evolved to sleep like dolphins. A creature in half sleep would be somewhat less than it was when completely awake. Its manner might depend on which half was asleep and which half was awake.
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**My cat sleeps all the time...**
I'm going to advocate that sleep need not be lost in your circumstances. The Circadian rhythm is convenient, but I'm not convinced my cat knows what it is. Or, perhaps, our Latin brothers and sisters, who enjoy *siesta.*
Rest can come at any time, whether through sleep or meditation.
However, as I think about it, it's not necessarily true that the Circadian rhythm doesn't exist on your planet, either. It's an assumption that it exists because of the day/night cycle. But it's just as likely that life accommodated the day/night cycle. In other words, it's easily believed that a *periodic cycle* exists with your creatures despite no day/night cycle.
**Even on a tidally-locked planet, there are cycles**
Life on a tidally-locked planet must have cycles. Things are born, grow old, and die. Energy is put into flowering, then fruit, then restoring. You run from the dragon until you get tired and are forced to stop and rest. Well... and then you die a gruesome death... but that's actually important.
**Darkness cometh from palm fronds**
I can easily imagine that part of the development of Earth's Circadian rythym came from the need for protection. You get tired, and not wanting to be [et](https://www.merriam-webster.com/dictionary/et) by the dragon, you find someplace well protected... out of sight... *dark,* where the dragon can't find you. (That you need protection regularly at night simply reinforces the rhythm.) A lot of the "rhythm" of your planet (and perhaps any planet) would come from the predator-prey fight/hide-for-your-life behavior.
Which brings us to palm fronds. Dragons are tall and, looking down, they can't see you sleeping beneath the fronds where you found a comfy place to sleep of the chase.
**Conclusion**
* Rhythms are going to happen for many reasons, the lack of a day/night cycle wouldn't stop that.
* The need for protection would naturally create an artificial "night" due to the need to hide from predators. Burrows in the ground and palm fronds leading to buildings via the dawn of intellect.
* Like my cat, one can rest at any time. Eat a big turkey meal and see how easy it is to fall asleep.
* Therefore, I don't think you'd need to replace sleep at all.
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Circadian rhythms regulate the *timing* of sleep. They do not create the need for it.
A body in an area without day-night cycles would still require sleep. People and animals who lived in Arctic regions before artificial light still slept in the height of summer or winter, as well as year-round, despite drastic changes in the amount of sun each day.
[People who are completely blind](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3202494/) (with zero awareness of light or who simply don't have eyes) still sleep and need to sleep (they're not just doing it for cultural reasons). But they often don't have 24-hour rhythms and may have disorders that stem from that.
One of the most important things we need sleep for is the generation of [Growth Hormone](https://en.wikipedia.org/wiki/Growth_hormone). GH is released primarily during sleep. It, and its downstream products such as IGF-1, regulate insulin use in the body, strength bones, produce breastmilk in lactating women, help with detoxification pathways, and dozens of other things.
GH also rebuilds muscle. If you're familiar with the rule for weightlifting that you only work out a set of muscles every other day or less, this is why. Exercise breaks down your muscles and restorative sleep releases GH that builds your muscles back up (bigger and stronger in many cases, but also what you need to maintain strength).
The myth is that only growing children need GH. The reality is that everyone needs it (not too much of it, but just the right amounts). Adults with GH deficiency (which can be a holdover from childhood or it can be adult-onset) are often tired and weak because their muscles aren't getting built back up after everyday activity like they should.
While other activities can release GH from the pituitary, deep sleep is really what you need to do it right. All humans need sleep and this is a large reason why.
Other reasons for sleep include: a full relaxation of the voluntary muscles (very hard to do without being asleep, though not impossible) and dreaming. The brain differences in various stages of [sleep and dreaming](https://www.webmd.com/mental-health/features/the-health-benefits-of-dreams#1) are important. They affect both our physical health and our mental health.
To replace sleep, you would still need a cyclical restorative process.
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**The place:** The United States of America.
**The time:** Whenever organised crime bosses think that they could have a chance of succeeding, between the English recognition of the US as an independent nation and now.
**The goal:** Organised crime figures to openly usurp government in a minimum of one entire US state, though preferably all of the USA.
I would consider government to have been usurped by organised crime if:
* The majority of the police have been bought, intimidated and/or killed such that they can no longer effectively even attempt to suppress organised crime other than as directed by the organised crime government.
* No effective intervention by military forces based in the controlled area is possible. This does not include the possibility of intervention by external military forces.
* Organised crime figures are openly in charge, and public revelation of their crimes can have no immediate negative consequences to them. I.e. they need make no pretence at being virtuous.
* The organised crime government need not make any pretence at following state or federal constitutions, and may use whatever means they want to add, remove or replace members of their government that they want.
The usurpation of government may take place by any feasible means, so long as it becomes apparent that the former constitutional government is no longer in effect.
The change of government must persist for a minimum of one year, preferably longer.
The organised crime figures who rise to usurp government may be real historical figures or may be plausible fictional characters.
Is this possible? If so, how? If not, how close could the USA come to having it occur?
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What is the difference between a protection racket and a tax office? The tax office answers to officials who have been elected/selected with the consent of the governed and who spend the funds for the common good, the protection racket does neither.
So imagine you have an organized group which subverts the electoral process to get their people elected as sheriff, governor, senator, president. They make systematic use of graveyard votes, voter suppression, gerrymandering, campaign finance violations, and so on. Once they are elected, they use their official powers to stop any investigation, either by ordering it closed or by starving it of funds -- or by appointing their pawns to do the investigating.
Sounds familiar? Well, not quite. There is gerrymandering and the like in the real world, but it is organized by political factions for what most participants believe to be the common good. Most follow the letter of the law while bending the spirit. There is no [organized crime](https://en.wikipedia.org/wiki/Organized_crime) as that is commonly defined, even if some actions might be criminal conspiracies between multiple actors.
Read about [Huey Long](https://en.wikipedia.org/wiki/Huey_Long) ...
**So how to get organized crime into your story?**
Imagine a couple of states or territories soon to become states with homogenous, disadvantaged groups of immigrants. Say there was a state-by-state [quota](https://en.wikipedia.org/wiki/National_Origins_Formula) system which encouraged this -- Irish in Boston, Italians in new York, Chinese in San Francisco. Meanwhile, WASPs tried to stay on top of the society/economy and the legal system -- they could do that because many immigrants were no citizens/voters yet. Ethnic-based OC groups took root to govern disenfranchised parallel societies.
Over the years more and more of these people are born citizens, and at some point of historical trouble the political establishment [reached out](https://en.wikipedia.org/wiki/American_Mafia#Cooperation_with_the_U.S._government) to them. The OC groups took the whole yard when they were offered an inch and decided to go legit. Their money and threats took one of the established parties in their state, or both. They know where enough bodies are buried (from their cooperation phase with the government) to limit Federal oversight.
**When could it happen?**
It takes decades-long shifts in immigration patterns and a trigger event. That could be the 1920s Communist scare (mob bosses to keep those rabble-rousers in check), or the 1860s Civil War (mob bosses to tell the soldiers that their enlistment isn't up yet, whatever the documents said), or the 1960s Civil Rights (mob bosses to keep farm workers in their place) -- anything to scare the establishment into unwise bargains.
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# Scenario 1: Wild West takeover
I am no expert in American history, but considering your requirements, the best case scenario would be that of the American expansion to the West.
That is, crime Lords get hold of US States *as they are created* (from territories onwards).
In this wild west scenario, which in my opinion is not much different from actual historical, albeit small-scale, settings, gangs become dominant because they set up some type of warlord scenario in which they act like as the paramilitary forces of some corrupt boss or family.
If you want this to be strictly crime-related, I suggest looking into the idea of some early-imported mafia families who, for some reasons, favour the South and West to the Eastern urbanised States. Why? Well, once there they could bribe government officials into awarding them the best land, start running smuggling errands across the border, exploit mining towns, fill pubs with working ladies and start exploiting mass migration to seize momentum and consolidate their power.
If things go wrong in the right way for you (allow me the pun), you would have most of the US set up for a Mexico-like scenario. Fast forward some 170 years (from 1850 to 1970) and you will have the perfect background for a series of cartels running entire Provinces.
In my opinion, even if you favour a late-20th Century scenario, Mexico should definitely be your case study. Because what you want has happened there... More than once.
# Additional notes
In addition, given the changes I am suggesting are supposed to happen throughout the 19th Century, my suggestion is to think of the possibility of the Civil War to end up into a Balkanized scenario. Again, with States run by warlord. By the 1920s such States would be no more advanced than nowadays' Transnistria... But maybe this is too far fetched as it would change not just American history but the entire world history.
On a different note, I expect other answers to linger more on the Roaring Thirties period... Great Depression could be a way into mafia leaders seizing control of counties first, and States later. That is, because during those times legislation was unduly harsh and bribery way too common. However, consider world wars usually make it harder for crime gangs to settle down, especially if the country involved is not being attacked on its own land.
# Another idea
Another idea would be to start small and unexpectedly. For example, in a far-away State like the Hawaii. I have heard of Ukrainian crime gangs buying off most of St. Kitts and Nevis in the Caribbeans, so I do not see why this couldn't happen elsewhere. However, as I know very little of Hawaii, most of my suggestions here remain way too general.
Hope this contributes.
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The Confederate States of America was an illegal organization and thus everything done by the CSA was illegal, even things which would have been legal if done by legal governments. Therefore, a large percentage of the USA was taken over by criminals and ruled by those criminals for up to four years in some places.
In fiction, the movie serial *Buck Rogers* (1939) shows the USA and the entire planet Earth, except for the Hidden City, taken over and ruled by a crime syndicate led by "Killer" Kane.
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## Very easily
On a long enough timeline, what you describe is inevitable.
* **Precondition: the political system is not adequately protected against corruption**
Safeguards against corruption come in many forms. Indeed, a society must institute multiple overlapping safeguards if it is to have any hope of avoiding rule by organized crime.
One reason countries *don't* do this is because politicians benefit directly from many kinds of corruption1, and countries generally depend on those same politicians to write the rules that would keep them honest. Unsurprisingly, these politicians "fail" to write and enforce rules that would take away their own opportunities for personal enrichment.
1 Political corruption benefits individual politicians until the corruption is so widespread that the people doing the corrupting acquire control over significant parts of the economy or government. From that point forward, political corruption stops being an opportunity for gain, becoming instead a skill that is necessary simply to avoid poverty, imprisonment, or death.
* **Assumption: criminals become wealthy**
One of the primary reasons people commit crimes is precisely to gain wealth they might not gain otherwise. Nobody cheats to get into *last* place. This is not to say that most criminals become rich -- they don't. Rather, crime is appealing as an alternative path to success, a path which becomes more appealing when there are few legal paths to success, such as when legal paths have been deliberately closed by people who are already wealthy.
* **Assumption: economic power translates into political power**
If you have or control enough wealth, you can use that wealth to manipulate the political system. This is light-years beyond simple bribery, which is usually cartoonishly depicted as a criminal secretly giving a politician a sack full of cash.
Here's an example: you are the CEO of a giant company, and you learn that some lawmakers are going to create a new law that would interfere with some of your favorite money-making schemes. So, you identify a couple lawmakers who are trying to make that happen, and you let them know that if they do this, you will relocate some of your businesses out of their districts, which will lead to an economic downturn in that area, which residents will blame the lawmaker for (and you can help make sure they *do* assign that blame). This is not a bribe, it's a threat. And there are a million ways to deliver that threat which prevent it being exposed as extortion.
Things are made infinitely worse when having lots of money becomes a prerequisite for becoming a lawmaker in the first place, as is the case in every country that allows political campaigns to raise and spend as much money as they like to win election.
---
If those conditions persist long enough, you'll reach a point where a significant amount of economic power is in the hands of people who have decided that government is merely an impediment to them being even richer, an impediment they want to remove.
These people will have something in common with organized crime: they want to see government smaller and weaker so it can't interfere with their private plans of getting rich(er).
The rich folks will pursue a few different strategies simultaneously:
* they will try to convince non-rich people to dislike and distrust government
* they will try to invent some kind of theory or political philosophy that justifies making government weak
+ without eliminating property rights, since acquiring personal property is their entire goal
+ while strengthening contract law, since contracts are one of the primary tools used by rich people to acquire manpower (from the non-rich) for their activities
* they will cultivate like-minded people with the goal of inserting them into government, because government is after all just made up of people and rules, and if those people are all working in concert to help you get rich and stay rich, then you'll find that government no longer interferes with your hoarding of wealth ("people are policy," as the saying goes)
The rich people who are not criminals will be working to weaken government because a weak government will be unable to punish them for "victimless" crimes like tax evasion and predatory business practices.
The organized-crime types will welcome this because it takes a lot of resources to detect and prosecute organized crime syndicates that are competent, and a weak government won't be able to do that.
Eventually the only people with economic or political power will be law-abiding rich people and rich organized crime figures. This is when the organized crime figures can take advantage of the fact that law-abiding rich people have been relying on stuff like social norms and laws to protect them from people who want what they have -- but that stuff only has power if the people in the situation choose to adhere to it. So the organized crime figures will then use force to seize their fortunes.
Finally: one enormous benefit of taking over the government is that this allows you to change the laws so that your previous crimes can't be punished and the crimes you're planning to commit in the future are no longer considered crimes. An especially audacious criminal might even pardon himself while in office for high crimes he committed in that office in an attempt to keep the office.
--
See also: Michels' ["iron law of oligarchy"](https://en.wikipedia.org/wiki/Iron_law_of_oligarchy).
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What your describing dose exist in Mexico today. For it to happen in the usa just recreate the conditions in Mexico.
1. USA is impoverished.
2. A close Neighbor becomes wealthy.
3. A valuable resource that can be found in American is made illegal by said neighbor.
4. Criminals in America begin Marketing this illegal product to its neighbor.
Once that in place you just give it enough time for your cartel to get enough of money to Essentially become a criminal version of Macdonald. Then they can begin controlling the government the same way modern corporations do only even more so since they have guns And the ethics or lack thereof to use them.
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Some political scientists consider the [modern](https://www.bbc.com/news/blogs-echochambers-27074746) [United](https://www.taylorfrancis.com/chapters/edit/10.4324/9780203155011-6/oligarchs-oligarchy-southeast-asia-jeffrey-winters) States of America to be a civil oligarchy under the control of various corporations and corporate powers. A group of criminal organizations could take over the United States in a similar fashion by bribing and controlling society in a manner similar to these corporations in real-life.Heck, plenty of organized criminals defend their criminal behavior with a front [organization](https://%20Front%20organization%20-%20Wikipediahttps://en.wikipedia.org%20%E2%80%BA%20wiki%20%E2%80%BA%20Front_organization) with businesses that seem legitimate acting as the legal face of the criminal organization. Thus, you can have a similar civil oligarchy with a bunch of criminal organizations using front corporations or corporations they have [infiltrated](https://www.ojp.gov/ncjrs/virtual-library/abstracts/organized-crime-goes-corporate-have-gangs-invaded-your-work-place) as go-betweens to influence the politics of the whole United States (or at least a single state where corruption and anti-bribery laws are pretty weak).
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Last year if Trump had succeded in invalidating the elections and taking over the capitol is a great example. And it was not far, he had apointed the proper judges during is mandate.
In fact I would presume that the current world leading figures are all a big criminal organization. They are super rich and get richer every day, they have legal inmunity against most charges and if they ever go to trial they have to face judges who where apointed by the government.
Do anyone think that what happend to Julian Assange was legal? or was it just a big organization (with the power to define what criminal is) bulling someone who has wronged them?
Edit: I've been pointed out that I am undermining my argument by saying "all world leaders are criminals". Its hard to make a list as I know mostly about my country, and I dont want to make too long of an oftopic with my answer, but. In spain the right party has been involved in several corruption cases uncovered by the partys accountant but as they can only be judged by judges apointed by them noone has ever been found gilty (exept said accountant). There was also a fire in the place where evidence was and alarm missfunctioned. There was a a case of suicidal with a hunting shotgun, some other ivolved fell twice down the stairs, another one died of the flue in a travel abroad so no autopsy could be aplied. All atourneys that would prosecute the case where removed from the case... and so one.
I guess that Berluskony in Italy, plenty of South america countries, Puttin in Russia, Comunist pary in china and a long etc. I amb not that much into politics, but its ptitty obvious.
The whole point of a criminal organization ruling a country is that they will never be found guilty.
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**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 have been working on a sci-fi story for a little while now, and have recently discovered that I made a very big error in assuming the position of Eris. The main issue is that I had forgotten to take into account the fact that Eris's orbit is radically askew from the solar system's plane, 44 degree inclination askew. I had figured it would be slightly off like Pluto, but calculating its position in the year 2428 puts it at roughly 84 AU from the sun and about as far away from the rest of the solar system as it gets. It would be almost perfectly at the bottom of the image below.
[](https://i.stack.imgur.com/lAkzT.gif)
With that understanding, I have to get a group of ships from Mars at 1.5 AU to Eris at 86.5 AU (in the year 2428). This puts me at an average speed of roughly 1 AU per day. This is kind of ridiculous, considering I am trying to work within a certain level of reasonableness, and had previously expected my ships to meet an average speed of 1 million kph, not 150 million kph. What I really need is a constant acceleration to the midpoint, and then deceleration to destination.
**What would the constant acceleration be given those perameters?**
**Also, might it be more efficient and/or economical to slingshot off a gas giant after leaving Mars instead? If so, which might be the most reasonable?**
[Answer]
If you have to travel 84 AUs in three months your average speed will be about 28 AUs per month. With an average of about 30.5 days per month or 91.5 days total the average speed will be about 0.918 AUs per day, 0.03825 AUs per hour, 0.0006375 AUs per minute, or 0.0000106 AUs per second.
To achieve such speeds with the least possible acceleration, the ship would have to accelerate constantly until it reached twice the average speed midway through the journey and then decelerate constantly for the rest of the voyage until it reached Eris.
Twice an average speed of about 0.0000106 AUs per second would be about 0.0000212 AUs per second, or 3,171,474.85884 meters per second. The middle point of a voyage of 91.5 days would be at about 45.75 days, or 1,098 hours, or 65,880 minutes, or 3,952,800 seconds.
Thus your space ship would have to accelerate at a rate of 0.8023362 meters per second per second, which is about 0.0818155 of one gravity.
One gravity of acceleration is 9.80665 meters per second per second, so accelerating at one gravity for 161,700.21 seconds would reach a speed of 1,585,737.42942 meters per second necessary to reach Eris in three months. 161,700.21 seconds would be 2,695.0035 minutes, 44.916725 hours, or 1.8715302 days.
Thus if your space ship can accelerate at one gravity, it could accelerate to the needed average speed in about 1.87 days, coast for a little less than 91.5 days, and then decelerate for about 1.87 days, to reach Eris.
Humans can and have survived accelerating at more than one gravity for short periods, but I wouldn't want to accelerate at even as little as 1.25 g for even as short a time as one day until and unless tests prove that would be safe, so one g can be considered the maximum possible acceleration for the mission to Eris.
Thus, according to my calculations, your space ship needs to accelerate constantly at 0.0818155 to 1.00 g, or 0.8023362 to 9.80665 meters per second per second, for days or months at a time in order for the mission to Eris to take three months.
[Answer]
If you have a constant-boost drive, you can get quite a long way in three months, even at just 1 G. Eliminate turnover, and you'd be close to 1/4 light speed in that time; assuming a turnover and stop at the end,you'd peak at around 12% c -- or average 6% c over the whole trip (roughly 14 light hours, you'd need about 224 hours). That means that Eris is less than two weeks at 1 G constant boost, from anywhere in the Solar system. Getting there in twelve weeks would require significantly less acceleration: average of .006 c, so peak of .012 c, 45 days to turnover and the same to stop, gives 1.8e6 m/s over 3.88e6 s, about .46 m/s^2, or just under .05 G.
At this kind of boost, there's no point in trying to tack on a mass like Jupiter -- you'll gain virtually nothing by it at best.
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**Context** : In a world, very similar to our good old Earth, with late medieval technology, a great kingdom has united a whole continent. Except, that is, for a small country, located southernmost of this middle-sized continent. This nation, being near the equator, faces intense drought all year long.
The thing is, our little country, while bearing with desert climate, needs to be able to feed its people and still sell a whole lot of excess to the kingdom. This nation of farmers have to provide at least half of the food for the whole continent. Assume a population of about 20 million people, total.
**The answer** :
A large river runs throughout the continent, finally meeting the sea deep inside the territory of our farming nation. I was thinking of giving it a huge delta, to make this land a bit more fertile. Think about the Nile, who provided ancient Egypt with plenty of arable land.
**The issue behind the answer** :
Said example (the Nile) was flooding. A whole lot. I don't want my little country to face this kind of event. Still, I want them to provide food for the greater kingdom North.
**The question** : given this setting, my question is the following :
**Is it possible for a country facing harsh climate to grow food in excess, thanks to a delta ?**
If so, how large would said delta need to be ? I read that flooding was what made the Nile bring all those useful sediments, and I don't know if a non-flooding river will impact farming in this environment.
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Edit : these are great answers, thanks a lot. Here’s a little clarification, for those who asked. The big kingdom relies on this particular country for several reasons. First, having unified the continent recently, the king is facing uprisings. To those filthy rebels, one must add external threats. Also, unstable political game. Our tiny farming country just isn’t enough of a threat to be dealt with.
Also, in the past, big almighty kingdom tried to invade and secure the food sources for themselves. Turned out that our peaceful farming nation is especially good at dodging conflicts, and has another ace up their sleeve. But that’s a story concern. So just assume that the great empire is forced to deal with this fact. Also, transporting the food is not an issue in this particular context, but feel free to bring more precision, to potentially help others.
[Answer]
Yes you can.
With 92 million people, Egypt has problems supporting its [population](http://weekly.ahram.org.eg/News/18897.aspx):
>
> Egypt is suffering from an acute food deficit, estimated at around 60
> per cent of its strategic food needs. It is barely self-sufficient in
> fruit, vegetables, potatoes and eggs, and it has to import 70 per cent
> of its needs in wheat and fava beans, 32 per cent of its sugar needs,
> all its food oil, lentils and yellow corn feed needs, and 60 per cent
> of its needs of red meat, butter and powdered milk.
>
>
>
But as we can see, it does produce enough vegetables and potatoes it requires, and only really needs help with wheat, beans and animal products. For a population of only 20 million, this shortfall would be non-existent and there would be a regular surplus.
There are a few things to consider here however.
* The [Green Revolution](http://www.pnas.org/content/109/31/12302)
Thanks to the green revolution we've tripled our food production. Your country won't have this, so with 20 million people almost all wheat and bean production will likely have to stay in the country to feed the people. This still leaves you a surplus of vegetables, especially root crops which can be transported without too much trouble.
* The Nile floods
The floods are an important part of the agriculture, farmers wanted large floods to replenish the soil. When the floods were high there was a surplus in food, when they were low there was a famine. Will your river and delta system rely on floods or will it be a more sedate river system?
If there are floods, you'll want your country to make dams and a complex irrigation system to control the flow of water. The [Aswan Dam](https://en.wikipedia.org/wiki/Aswan_Dam#Drought_protection,_agricultural_production_and_employment) on the Nile has many problems with silt, but it regulates the annual floods ensuring that there's always enough water for the farmers.
Without an annual flood, your country will need to use a lot of animal fertilizer and compost to keep the soil fertile and depend even more heavily on the delta. Having enough animals for fertilizer will take food away from people, depending on [the animal](https://www.noble.org/news/publications/ag-news-and-views/2011/february/the-efficiency-of-beef-production/) you'll need 2.5-3.5 pounds of grain for 1 pound of meat.
* Arable land
One of the reasons Egypt has trouble supporting it's population is that a lot of the farmland has been urbanized. With a smaller population this isn't as big of a problem for your country. However, if all the major cities are in the delta region, even a medieval city could start cutting into it's food supply through polluting the water, using too much of it for other purposes, and of course urban sprawl.
If there are annual floods, which are controlled by dams and irrigation, it would help ensure the land stays arable for farming rather than getting turned into a city. Most cities and towns would be at the edges of the delta or on the larger and higher bits of land, while villages would be in the delta itself.
As you [can see](http://www.diercke.com/kartenansicht.xtp?artId=978-3-14-100790-9&stichwort=saltpan&fs=1), the majority of large cities are at the start and extreme edges of the Nile delta.
[](https://i.stack.imgur.com/gQ9Yq.jpg)
With rivers that don't have regular floods, like the Yangtze River Delta, cities and large towns are built directly on the shore of the river, reducing the arable land, and when a flood does occur it's typically very devastating.
So your country can export food, likely in large quantities, but it's not a simple matter of providing enough land, how it's used and nourished is also critical.
[Answer]
No, but not because there wouldn't be enough food.
Ancient Egypt may serve as a model of a large river delta in desert climate feeding a country's population. There are [various estimates](https://thetorah.com/ancient-egypt-population-estimates-slaves-and-citizens/) of its population, but the most generous is 7.5 million. Assuming that in our case the delta is bigger, and farmers have better crops than ancient Egyptians had, it's perfectly imaginable that a pre-industrial delta can feed 20 million.
But the main problem will be **logistics**. The population is not residing in or around the delta, it is spread around the continent. We would need large amounts of cargo to travel in excess of 1000 km on a regular basis. This was unheard of in the ancient/medieval world. Egypt could ferry grain up and down the Nile, but not much on the roads. Rome had solved the problem of feeding the capital (1+ million population), but the distances were much shorter. China had most of its population settled around fertile rivers.
Not to mention that those were problems solved domestically, and these countries had decades or centuries to work them out before they seen their population rise. Massive trade of goods across multiple borders is almost impossible to arrange. If a war breaks out in one country, all the countries on the other side of the delta will starve. Even in peacetime, the "upstream" country would impose tariffs, which would normally make trade profitable only for valuable goods. And even without tariffs, cost of shipping goods for 1000+ km in a wagon would make the food very expensive - it will cost more to ship than to raise and harvest. Draft animals need to eat too. It's a problem similar to rocketry - in order to send a small probe to space, we need to start with a much large amount of fuel on the launching pad.
However, if your large river with its tributaries cover much of the continent, the problem becomes simpler, because you don't need to deal with roads and draft animals. Still, for a sizeable ancient/medieval country, getting most of its food via trade would be unprecedented.
P.S. I think it would be realistic that this delta provides not all the food for the continent, but only the necessary extra amount for more advanced nations which have cities that can't feed themselves from neighboring lands. When trade is stable, everything is well, but when not...
[Answer]
Let's run some numbers.
First, we'll need to know how much food 20 million people require to sustain themselves. Fortunately, [we've already done that math](https://worldbuilding.stackexchange.com/q/9582/6986). Assuming we're only growing sweet potatoes, and $1 \text{ km}^2$ of cropland will feed 2,350 people, then we're going to need $8,510.6 \text{ km}^2$ of cropland to feed 20 million people.
We're in luck! Turns out there's plenty of precedent on Earth to support a delta this large. The largest [river delta](https://en.wikipedia.org/wiki/River_delta#Examples_of_deltas) in the world is the Ganges/Brahmaputra combination delta, at $59,000 \text{ km}^2$.
"But wait!" you say. "That delta lies in Bangladesh, in a [tropical climate](https://en.wikipedia.org/wiki/Bangladesh#Climate)."
Not to worry, there's more examples to be had. Specifically, one you've already researched. The [Nile Delta](http://www.delta-alliance.org/deltas/nile-delta) has a land area of $12,512 \text{ km}^2$ and it exists in an arid climate.
So feel free to copy Egypt onto your world map. If anyone notices the eraser marks around the (new) name, just say it's an unusual geological feature.
[Answer]
If you have enough sun and a large river, with natural fertilizers in water, you only need to conduct the water to every point of the area. And yes, a delta is ideal for that.
But if the country is near the equator, you needn't delta for watering - in the equatorial climate you have heavy rains every day - but for these natural fertilizers. And having delta and daily rains you are getting a swamp. To prevent this, you need some special plants to drink and evaporate all extra water. Or you need very different physical geography due to different slant of the planet's axis, in order to make the equator dry.
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I'm trying to build a world set in the future, but mainly using modern culture and technology. I plan on this world to be explored mainly through illustration, so I need to design how things look. One of the problems I've been having is how to distinguish between members of different militaries. On the one hand, I don't want to do crazy things like inventing impractical armors or making armies wear impractical colors. On the other hand, I also don't want these armies to be comprised of men in identical camo and pocketed vests.
Are there techniques (whether in real-world militaries or in other worldbuilding efforts) that allow members of different armies to remain distinct without sacrificing practicality?
[Answer]
* There can be distinctive shapes for [helmets](https://en.wikipedia.org/wiki/Personnel_Armor_System_for_Ground_Troops), backpacks, [rifles](https://en.wikipedia.org/wiki/FAMAS), etc.
* Camouflage colors can vary *slighty* depending on the intended terrain. One side might be prepared to fight in [temperate forests](https://commons.wikimedia.org/wiki/File:Chieftain_Tank_(9628802829).jpg), the other is prepared for [temperate urban areas](https://commons.wikimedia.org/wiki/File:British_Chieftain_tanks.JPEG).
* To some degree, there are "designer" camo patters. Compare [MARPAT](https://en.wikipedia.org/wiki/MARPAT) and [Flecktarn](https://en.wikipedia.org/wiki/Flecktarn).
* Deliberate recognition signals include IR reflective markers when one side has good vision gear and the other doesn't.
[Answer]
Define 'practical colours'.
If the aim of warfare is simply to kill as many people as possible then your colours are, practically speaking, very limited.
If, however, your aim is to impress, intimidate or let the civilian populace know that 'hey, the *good guys* are here now!', then it makes more sense to drape a big red-white-and-blue banner over your shoulders and throw piñatas to the populace.
Which leads to my point: If the state of military action in your world is such that being able to easily identify troops (either so your enemy knows who is hitting them, so you don't shoot your own people or so your opponents think 'golly, what a sharply turned out regiment!' and flee) is a higher priority *in the minds of the people calling the shots* then you will end up with brightly coloured, brashly nationalistic uniforms.
These may be thoroughly impractical for the purposes of not getting shot, but brilliant for whatever purpose the shot callers want.
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As an example scenario: A government think tank in the Federation of Notreal decides that civilian resistance will decrease if soldiers appear nonthreatening. Notreally Soldiers in their rival Baddudistan are all issued mandatory 'happy face' body armour. Now you can easily tell the Notreally soldiers from the Baddudes because one side have happy faces on their chests. The people with boots on the ground know this is ridiculous, but it doesn't change their orders.
As it turns out the smily faces reduce civilian resistance, Notreal annexes Baddudistan and the idea of 'smily faces are better than camo' becomes firmly entrenched in the national psyche, remaining part of the uniform even when it's a bloody stupid idea.
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Now the above is an absurd example, but it's meant to illustrate that a different uniform might have an advantage that isn't immediately obvious to the people being shot at on the ground (or actually justified), but which then becomes part of a national identity that people don't want to sacrifice (which may be important in an all-out conscription led war of attrition).
And the infantrymen will hate their officers forevermore.
[Answer]
One thing you can take a look at is WW2 helmets. [German](http://gwh.rockbridgeservic.netdna-cdn.com/wp-content/uploads/2017/02/H313-1-WWII-M40-Q66-German-Luftwaffe-Helmet.jpg) helmets were different from [US](https://www.toppots.net/thumb3.php?img=download/506thCptArtefakeB02V2.jpg) helmets. Also, uniforms often had a unique style to them that were practical but distinctly different. Take the [Japanese](https://s-media-cache-ak0.pinimg.com/originals/78/4f/ac/784face4b3a88ac77bd55d90ea380652.jpg) vs [USA](http://1.bp.blogspot.com/-UjlnwlPwaAw/U3-q8aGTDkI/AAAAAAAAF0I/aXxG4h6VXog/s1600/10322751_262908653894914_1761491284310771543_n.jpg) as an example. Also flags were HUGE in being this distinct difference. Going back to ancient times where they would march into battle with the flag bearers waiving the regional emblem which wasn't so different during WW2 when flags would be posted outside of buildings for everyone to see who occupied it. While you may use the same camo colors, the pattern itself would be different. Take a look at [US Marine Snow Camo](https://markosun.files.wordpress.com/2010/02/marinessnow_marpat.jpg) VS [Russian Snow Camo](https://domhyde.files.wordpress.com/2009/12/finn-m05.jpg). All are different but practical.
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The U.S. military uses dark (yet still identifiable) insignia [patches](http://www.galaxyarmynavy.com/prodimages/giant/1796.jpg) on their uniforms to distinguish rank. You could apply this to a faction-based design that is similar and large enough to be noticed in your illustrated scenes.
[Answer]
# Different occasions call for different uniforms
Not every moment of a soldier's life is spent staring down the sights of his rifle. Officers especially get extremely fancy [mess dress](https://en.wikipedia.org/wiki/Mess_dress). Even the ordinary Limey serviceman has [fourteen different uniforms](https://en.wikipedia.org/wiki/Uniforms_of_the_British_Army) from full dress (ceremonial uniforms) to barrack dress (complete with specific directions for how sleeves should be rolled up).
# Different equipment and fashions
Not all militaries are well-funded - some might shower their guys with the latest tacticool tech, and others make do with surplus Mosins. The equipment surrounding them would also be different - a soldier is rarely far away from various jeeps, artillery, tanks, helicopters, what have you. Heavy weapons such as rocket launchers or fixed machine guns tend to be more distinct than rifles and pistols. Speaking of pistols - the rules for a soldier's weapon, side arm, and bayonet are very different around the world!
Soldiers are also people, and people look different. Most militaries are made up of one or a few ethnic groups, so you get skin, hair, and eye color to play with, as well as physical size, facial hair, jewelry, etc.
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With colony cities on the moon and merchant ships mining asteroids, humanity has begun to colonize the solar system. Most of these entities are self-governing and trading is a very important business since most of them are only barely capable to provide for their own basic needs.
out of the many goods that can be produced in an emerging space economy, which one would make for a good currency? (I'm talking about commodity money, so I want the currency being a piece of something valuable)
[Answer]
Since the purpose of money is essentially to act as a common and fungible unit for accounting purposes (rather than trying to decide how many cows this pile of apples is worth, then trading the cows for lumber....), there are several ways to go, depending on the philosophical and political foundations of the society in space.
1. Fiat currency. Most of the money in todays world is fiat currency, and essentially has value because the issuing government *says* it has value, and because enough people *believe* the promise of value. This is behind the "Full faith and credit" backing of the USD, for example. If enough people no longer believe in the value of the currency for whatever reason, then the currency becomes valueless. Fiat currency has issues in a solar system setting, since money from a distant asteroid is pretty unknown outside the local area, and you have no "full faith and credit" in this place.
2. Commodity backed currency. Money was historically backed by silver for centuries (stop and parse the meaning of "Pound Sterling"), and more recently by gold (the US gold standard set gold at $35 USD/troy ounce). Commodity based currency is inflation proof, but can cause distortions based on the supply of the backing commodity (this is why silver backed money, being much more common and available than gold). Mining is problematic, since an unexpected strike can flood the market with a commodity, while prolonged economic growth without new supplies of the commodity can strain the system since there isn't enough money to support growth.
3. Digital/cryptocurrency. There could be some debate about this, since electronic transfers of fiat money through the SWIFT system or even your ATM/Interac card resemble this to a certain extent. The prime difference is cryptocurrency is not issued by governments and cannot be (easily) manipulated or debased by governments or the issuing party. This solves much of the "faith" issues inherent in fiat currency, but the user may not know "who" the issuer is, and governments can make things difficult by refusing to convert cryptocurrency into whatever the local unit of exchange is, making holding cryptocurrency inconvenient (you would either have to convert it on the black market, or go through chain of converting cryptocurrency to an "acceptable" currency, then into the local currency. This could be either mitigated or amplified depending on the attitude of local merchants. If they accept cryptocurrency, then all is good, but if they refuse it, then you are stuck with the "full faith and credit" argument again.
4. Locally issued national currency. This was used to my knowledge in the US during the era of "Free Banking" and by Canada up until the late 1940's, where a bank could issue the national currency backed by its own assets. Bank runs and other financial misadventures were localized because the currency was asset based (bank loans and mortgages are the assets of a bank, your deposit is a liability to the bank...). Since much of this depends on trust (is the bank cooking the books?), then it has local applications in an asteroid or space colony, but would tend to break down over even planetary scales ("issued by the bank of what?").
I suspect there will be a multitude of currency systems in place, ranging from local currencies in colonies or asteroids to fully fledged, energy backed currencies which are issues as cryptocurrency to ensure full faith and credit (you can always buy a Kw/h with one Solar Dollar, for example). Trade currencies like the Solar Dollar will be used in "international" trade due to convenience, while local currencies will be more convenient for small local purchases (a Solar Dollar might be worth far too much to purchase a cup of coffee with, for example).
[Answer]
## [Bitcoin](https://en.wikipedia.org/wiki/Bitcoin), or some other form of government-endorsed [cyptocurrency](https://en.wikipedia.org/wiki/Cryptocurrency). Essentially, something digital.
>
> "Space," it says, "is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space, listen..."
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> *The Hitchhiker's Guide to the Galaxy*, Douglas Adams
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It takes days to get to the Moon, and months to get to Mars. Do you really want to have to send a ship all that way just to make a payment for spaceship insurance, or to pay taxes, or to pay someone to mine for you on another planet? Of course not. That's slow and inefficient, and carries dangers. What if the ship crashes, or explodes? For planet-to-planet transactions, this is a terrible mode of payment.
Use cryptocurrency instead, sent through signals in radio transmissions. Data in the transmissions can encode how much money is being sent from whom to whom. When you're on planets, you can just carry a card - like a credit card - and swipe that. The card contains money connected to your "Bitcoin" digital supply.
A government - government*s*, really - would need to endorse the currency, to ensure its stability. That's one issue that Bitcoin has faced for a long time. In fact, you'll definitely need international approval. I highly doubt that only one country is involved in this space exploration. Cooperation is the only viable option.
[Answer]
# It doesn't matter if you're thinking of traditional currency.
At the end of the day, they're all the same. Given the vastness of space, anything is effectively a [fiat currency](http://www.investopedia.com/terms/f/fiatmoney.asp). The addiction people have to the **shiny!** that is gold, despite its effective low value, will be lost in the shear quantity available. Gold merely becomes a fiat currency that's heavy, awkward and expensive to transport.
Value can only be given to that whose value is accepted. All currencies will be fiat currencies, and that's just a matter of the accepted value of any given fiat currency.
For those who choose to say that ultimately no fiat currency has value, I say you are correct but in return I ask a different question: **What, in space, has value?**
The trouble with the follow up question is that it depends. If I'm at an asteroid mining colony then food with flavour has the most value. If I'm on a planet then maybe the resources from the asteroids have the most value.
I'd say Terry Pratchett was right when he said: Time. The time of your life.
>
> Jalo fumbled in a belt pouch and brought out a was of 10,000 Day bills. Company scrip was harder than most world currencies. Any one of them represented almost twenty-eight years of extended life if cashed at a Company trading post. The Company's credit was the best. It paid in extended futures.
>
>
>
This sort of thing of course depends on available technology, it's something that cannot be estimated from our point in space and time as we don't know the technology that will be available to future space traders.
[Answer]
# No change
The US Dollar is an automated electronic international [exchange system](https://en.wikipedia.org/wiki/Clearing_%28finance%29#United_States_payment_system). It is accessible from pretty much anywhere, makes [$14 trillion](http://www.zerohedge.com/news/how-14-trillion-flows-every-day-through-us-financial-system) in financial transactions every day. It already accounts for varying regions of control (by national central banks), payments between banks, nations, etc. There is pretty much no need for any other system in the near-future.
The only issue with the current system is latency. In a solar-system civilization there will start to be significant latency issues in transactions between Titan and Venus, for example. This is mostly an engineering problem, rather than a design problem. Trying to day trade with 15 min lag in the Venusian Cloud City Stock Exchange will probably not be a great plan; but there is no reason that current financial transaction queues can't account for lag time in arriving transactions.
[Answer]
Conventional money usually needs some kind of central "government", a federal bank that maintains many of its properties (including the amount of money on the market) and provides its value - at least, fix me if I'm wrong, but as far as I know, current system of money is based on the fact that we *trust* in that it's accepted.
This way, if your people **have the connection** to the other world, it's a perfectly viable option to use either conventional (like USD) or cryptocurrency. (Bitcoin) The latter theoretically can work without it, as well - what I try to convey is that in this case, your people don't have to have their own federal bank, which makes things easier. However, they will rely on the "outer authority".
If these people **are isolated or alone**, then you have to build the base of the economy from scratch. Depending on what kind of economy you desire to build, it may vary, but in a money-based system, a backing product is necessary - like gold on Earth. It has to be infinitely divisible, very rare and generally accepted, just to name some of the most important requirements. Rare metals, metallic alloys, minerals from asteroids - you name it.
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There's a midway situation, too, and in fact, I try to explore this one: **there's a connection, but the other authorities are hostile**. It means you can't really use their currency as a direct form of money, but through smuggling and other means of the black economy can bring in money, that, from that point, can partially be considered value that is part of the space community. This way, I presume, your space communities can profit from these illegal connections, with smaller exposure to the risk caused by the decisions of the federal bank regulating given currency.
*I'm sorry for inappropriate grammar; I was in hurry a bit.*
[Answer]
## Energy.
OP's question is actually similar to this one [interplanetary trade in around 2400 CE](https://worldbuilding.stackexchange.com/q/60125/20315) by the nature of the problem.
As a piece of something valuable, even with space scarcity of resources(maybe), I'm glad to present you, the latest invention in energy money - energy diamond.
[Scientists are turning nuclear waste into super-efficient diamond batteries](http://www.sciencealert.com/scientists-are-turning-nuclear-waste-into-super-efficient-diamond-batteries)
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> With a half-life of 5,730 years.
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> A diamond beta-battery containing 1 gram of C14 will deliver 15 Joules per day, and will continue to produce this level of output for 5,730 years — so its total energy storage rating is 2.7 TeraJ.
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As energy it has cost about 75'000\$ per gram (0.1\$ per kWh), compare it to the current price of gold \$38,214.73 per kg.
Or it is 75'000'000 per tonne, even with SpaceX ITS prices of projected transporting cost with 140'000 per tonne it worth to transport in physical form if there is such a wish.
* not so easy, in first place because energy in space is cheaper, but best of 3 worlds (energy, matter, and good cutting tool) for those who like physical transfer.
But sure energy does not have to be physically transferred in cases when it is not needed, or impossible to transfer. Same way as gold backed money do not transfer gold.
### Purchasing power of energy in different places
* This section is less about having tokens, which OP was asking for, but again more about why energy may be valid as money.
Purchasing power of energy will be different in different places. But to use the energy in a different place one have to deliver that energy to the place, or exchange already present energy in the place to already present energy in another place, if one like to use it there or order something there.
Price for energy from one place will depend on abundance of the energy in that place, abundance of matter in that place, cost of delivering goods and services from/to the place, technologies available, demand for services in the place, offers (what they can do with the energy, and how much other needs what they can do) in the place, energy sources available in different places etc etc.
Purchasing power of energy will define direction from which place to which place this energy is flowing.
If as an example a space station can produce lots of energy for cheap(effort, matter, work hours), but can't produce anything else(for some reason) there are 2 ways to solve the problem
* deliver technologies and/or matter to the space station
* deliver energy to other places where the energy can be actually used to produce useful technologies or products or services.
It works same way as one may have a house in one country, but to actually use it -- one have to be in that house or rent it to others - for money or for services or use the house for other profitable operations.
Same way as currencies, you may have currency of a other country in the country, but one can't directly use that currency to buy something, because they do not accept it as payment, they accept their own currency as payment. They do so because of a reason, artificial and practical reasons. And for those reasons one have to use exchange service to get a currency of the country where he is at the moment, directly or indirectly (as by asking will you accept my money, and they maybe will but how much you money worth they will know from exchange rates of that currency)
Same for energy, one may have Terra Watts of power production on a space station, but if one can't use this energy for something useful it is worthless. If he have to obtain matter and deliver it from Jupiter, to be able to do something with that energy it may be not so much overall.
Also different services will cost different price - on earth recycling is expensive process, because they do not have lot of energy, so they make big trash fields - it is cheaper for them.
On a space station, recycling is cheap, because of cheap energy, but making some kind of trash storage is expensive, because delivery of new materials may be expensive, or just -- worth in energy in the place where it can be obtained and in energy needed to deliver it to the station.
Delivery and gathering the matter from Jupiter will cost about 300kWh/kg (depends on technology you have for gathering), delivery of that matter may cost from Jupiter to some station near earth will cost X amount of matter and energy (depends on technology used in delivery)
In general, it will stimulate matter to flow in a direction where it can be used, energy flow in direction where it can be used, and will stimulate to develop energy efficient technologies.
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In an emerging space era, the currency model wouldn't be that far from today's era. Since even we can get a new source of gold in another place beside earth, a space mining process would be more complicated hence need more investment that would prevent a massive drop in gold values.
When you say about trading, which means fuels (in any forms) would be a precious value that can give more affect to the economy. Politic is also in play here as infant government in remote space area who just barely capable to provide basic needs may need and abide to a 'parent government' (maybe in earth or other large capital planets) that shares a common currency. (So we may see a Saturn Dollar $$)
Another possible things is a evolved model of currency that's not based on scarcity of precious tangible things, says like Bitcoins. This will be one of a possible solutions for currency to prevent our economy to fall to chaos when human can get their hands on a planet that entirely made of diamonds or gold.
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Hundreds of years ago, the world as we know it came to an end for various reasons. Mass death, mass agricultural failure, a complete breakdown of all economies and transportation networks along with essentially all nations seeking to function as nations.
But humanity survived, the descendants of the survivors have lost most the technology their ancestors had (but not all!). Would it be plausible for them to dig up the remains buildings, vehicles and so on in order to recycle the raw materials? I have read that iron, and possible other metals, can be recycled simply by melting them down and skimming off the impurities. Would it still be possible after this amount of time? Is there any challenge to this that I'm missing? Once they start doing this, would recyclable materials be depleted very quickly?
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This is not only feasible but preferable. If I was living in that world and needed to mine and process metals, I would get them out of the ruins and leftover items from those ancient times.
First, as to how long the metal will last. We are still finding metal coins from the Roman Empire. It is amazing how long metal will last. Some of it might be unusable, but even with medieval technology, you could smelt metal ore with a lot more impurities than what you would find in say the ruins of a skyscraper. Mind you, a lot of the ore that is pulled out of mines is combined with other elements or is Iron Oxide (Fe2O3). Pulling the oxygen off is part of the smelting process, so rusty iron, is just fine for smelting.
As to safety, I would rather mine a collapsed building or beached aircraft carrier than mine into the side of a mountain. Dangerous, absolutely, but mining for ore is far more so.
And the melting temperature of steel (1370 C) is actually lower than the melting temperature of iron you would dig out of the ground (1510 C), which is a bigger part of the reason that recycling can be profitable. If you could mine and process iron ore in medieval times, you will be able to mine and process steel from ruined buildings, beached ships, etc.
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Reducing oxidized (rusted) iron to usable iron metal is the function of a blast furnace. These were developed in China around two millennia ago, so it's definitely within reach of post-apocalyptic technology.
All you would need is coal/charcoal, ceramics (clay) to create the body of the furnace, and a means to create bellows (wood and leather?).
Bloomeries are even simpler and can be used to create wrought iron.
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It is very possible.
Ideally you would first look for material which is in a useful state as it is. Steel would be a high priority for making tools etc and while steel *can* corrode quickly in the wrong conditions it is entirely plausible that heavier sections in sheltered locations could still be sound after several centuries. A good target would be machine tools and plant where high quality steel parts would be well protected inside the body of the machine and also covered in oil or grease.
Indeed it is not entirely implausible that a significant number of machines may still be restorable condition. There are plenty of 100+ year old lathes and milling machines still in operation.
Many common and useful non-ferrous metals are very easy to recycle and can just be melted in a crucible at fairly moderate temperatures which are easy to achieve with say a charcoal furnace. This includes bronze, brass, lead aluminium and copper. This process is sufficiently obvious that it is entirely plausible that it could be done with relatively little specialist knowledge or experience.
Remelting cast iron is a bit more difficult as some care needs to be taken to maintain the proper carbon content but it can be done with pretty simple equipment if you understand the process.
There is a fair chance that the amount of metal currently in circulation would keep a severely depleted population going for a long time without needing to start smelting ferrous metals from ore (or severely corroded stock)
Global annual steel production is in the order of hundreds of millions of tons so there is a lot of it about so you only need a small proportion to be accessible and in reasonably good condition to have very large stocks available and without large scale industrial projects and facilities there is a limit to the amount you are going to be able to use. Indeed before you even need to start recycling there will be plenty just stacked up in warehouses and rail yards.
A relatively simple forge using a medieval level of technology could effectively recycle most metals, although remelting steel is a bit beyond this setup it is entirely possible to forge weld assorted bits of scrap into usable billets without needing to melt it.
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humans have been recycling old material forever. taking the stone off of buildings, melting down statues, ect. they will likely recycle a lot more than metal, modern glass would be valuable, and concrete and asphalt can be cut into blocks, as long as the things exist they will find uses for them. and digging the debris off old cities would be a lot easier than searching for bog iron much less digging a mine in solid rock.
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Is it possible to create a large space station orbiting the sun around 10 million kilometers away from the sun? It would be a large settlement which houses around 200 people. Energy would not be a problem provided they bring solar panels with them. So is this possible and would 10 million kilometers be too small? Could they create sustainability? Humans would have 10 years to build it and our current technology plus any new tech they develop in the next 10 years.
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Solar radiation increases/decreases according to an inverse-squared principle, much like sound on Earth. The closer you get, the exponentially higher the energy of the sun will become. To put it in perspective, check out <http://www.pveducation.org/pvcdrom/properties-of-sunlight/solar-radiation-in-space>
According to those calculations, if you are 10 million km from the sun, you will get something like 290,000 watts per square meter. That's ~200 times more intense than the sunlight on Earth. Things will get rather toasty in our space station.
So how can we prevent this heat from cooking our intrepid stationkeepers? A reflector can help in a major way (there are reflectors designed to reflect gigawatt lasers, so they can handle the sun), but even the best mirrors are about 99.9% efficient, so our station will receive about 2.5x the energy of the earth *even behind a giant mirror*. There are better options, though. A reflector paired with a heat shield, or layered reflectors and heat shields, can do wonders. Certain high-temperature ceramics can exist up to temperatures in the thousands of degrees C. These could shield the station (hopefully from behind a reflector) and keep the inhabitants relatively cool.
The real issue is that the leading edge of the station (the side facing the sun) will erode eventually. Space is an inhospitable place, and even if the station isn't baked to a crisp, micrometer strikes will bring the reflector plate down eventually, and the ceramics will chip away. Once this shield is gone, the station will literally be toast. Hope your folks have a backup plan.
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<http://www.popsci.com/science/article/2010-07/how-close-could-person-get-sun-and-survive>
This article from popular science has some good information.
>
> Riding in the space shuttle, though, someone could get much closer to
> our star. The ship's reinforced carbon-carbon heat shield is designed
> to withstand temperatures of up to 4,700° to ensure that the
> spacecraft and its passengers can survive the friction heat generated
> when it reenters the atmosphere from orbit. If the shield wrapped the
> entire shuttle, McNutt says, astronauts could fly to within 1.3
> million miles of the sun (roughly the two-yard line). But the
> integrity of the shield degrades rapidly above 4,700°, and the cockpit
> would begin to cook. "I would advise turning away from the sun well
> before that point," McNutt says. Much hotter than that, the shields
> would fail altogether, and the vehicle would combust in less than a
> minute.
>
>
> Of course, just getting that close to the sun would be quite an
> accomplishment, says NASA radiation-health officer Eddie Semones. The
> constant exposure to cosmic radiation during the voyage would most
> likely prove fatal before the astronauts crossed the 50-yard line.
>
>
>
<https://www.youtube.com/watch?v=LIpDpRUVrNU>
So the answer seems to be YES, if you can survive the insane amount of crazy radiation. In KM 1.3m milion is 2,092,147km so being 5x further away would be good. You would probably have to generate a large magnetic fields with backup generators to block the radiation. If they ever failed even for a short time everyone dies.
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It is technically feasible so long as the temperature can be controlled, as suggested by MozerShmozer. Indeed his answer suggests why anyone would want to do such a thing; they will be able to accommodate a very high energy lifestyle.
Orbiting the sun at that distance will be much like orbiting any other astronomical body, you will essentially be in free fall (unless the station is rotating to create the effect of gravity), and that near the sun you might want to deploy a large "wake shield" ahead of your orbit to protect the station from orbiting particles that would also accumulate due to the Suns's massive gravity, not to mention the particles emitted by the sun itself.
[](https://i.stack.imgur.com/kofQ3.jpg)
Another trick which would work very well in that region is to deploy a solar sail of sufficient size to counteract the gravitational pull of the Sun and suspend your station under it. This concept (by Robert L Forward) is known as a [Statite](https://en.wikipedia.org/wiki/Statite). The patent drawing shows a statite "hovering" over Earth, with sufficient planning you could build a statute capable of hovering almost anywhere in the Solar System.
[](https://i.stack.imgur.com/xpY6A.png)
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To steal from Brin's *Sundiver* (and to a degree, Niven's *Ringworld*), an hypothetical high-temperature superconductor tied to a very efficient laser could shed whatever excess heat by beaming it back into the sun. (Which is the entire premise of *Sundiver*)
Naturally, such superconductor materials are made of equal parts science and *fiction*, …
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Yes, a space station settlement could orbit the sun, but, as others pointed out, preferably at a much larger distance. In fact, the earth orbits at about the "perfect" distance of 150 million km, so that it does not get too hot or too cold.
The issue is the energy needed to escape from Earth. It took a lot of energy to bring the international space station at an orbit of just 400 km above sea level. If you look at a (physical) globe of say 30 cm diameter, and at the distance Amsterdam to Paris, you understand that ISS circles just a few millimeters around that globe. To bring that same ISS in a substantially higher orbit, or even to escape velocity, would need unimaginable amounts of energy. And your 200 person space station is much bigger than ISS.
Could this be done? Practically: no. Theoretically: not in 10 years. In your phantasy (phantastically): of course.
My question is: why not use the Earth itself as such space station?
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## Yes
* distance from the Sun, 30 light seconds
* visual size of the Sun at 10kk km will be 8° (diameter)
* radius of the Sun, $\approx$ 2.3 light second (diameter 4.6 light second)
* effective temperature of absolute black body, sun side surface, $\small \approx 1500K$
* energy flux, $\small \approx300kW/m^2$
This is not an easy situation, specially for those who do not have much experience in space building, and do not have much stuff to operate in the space ad proven technologies needed for such operation. So this 10year+10year of OP's setup - is source of an uncertainty. We may develop technologies which may make this task an easy task, but will we do it or not in the time, I do not know. Thus I suggest one of possible, but sort of low tech solution, which isn't state of art. And this is **not** Only solution in any way.
Body with 400m radius will make cone of full shadow, height of that cone will be 5720m (1:14.3 ratio).
Ratio of base area(let it be circle) to side area of that cone in our case where $r \ll h$, is also 1:14.3
full surface area of a cone is ${\pi r^2 + \pi r \sqrt{r^2 + h^2}} = \text{base} + \text{side area}$
$\frac {\pi r \sqrt{h^2+r^2}}{\pi r^2} = \sqrt{\frac{h^2+r^2}{r^2}} = \sqrt{1 + \frac{h^2}{r^2}} = \frac{h}{r} \sqrt{1+\frac{r^2}{h^2}} \approx \frac{h}{r} + \frac{1}{2} \frac{r^2}{h^2}$
$\frac{h}{r} = \cot(4 \deg) \approx 14.30$ , $\frac{1}{2} \frac{h^2}{r^2} \approx 0.00244$ which is less then $\frac{1}{6000} \text{ of } \frac{h}{r}$
* formulas was not totally necessary, but, who knows
This **1:14.30** ratio is actually important for station
Energy from the bottom of the station have to be dissipated by surface which is in the shadow. Near the cone it will be area of half shadow, where flux will change from 0 to full 300kW/m2 solar energy flow, using that gray area we may improve overall energy generation, but consideration of this matter is omitted.
## Bottom
One may use mirrors for the bottom of the station-cone, to reflect the solar energy, but reducing reflective efficiency of this solution have to be expected at this distance from the Sun.
Sun temperature is around [5772K](http://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html), and spectrum is divided into the following: 5% of the total energy is gamma and UV; 51% 300-800 nm, 41% 800-3300 nm.
The 5% is significant amount of energy at that orbit, and as high energy spectrum it will erode the initially perfect mirror, or layers of reflective materials, specially protective coating if there is such one - more imperfections faster the erosion will develop. It can be solved through constantly refurbishing of the mirror. I do not count solar wind particles erosion, even for perfect reflective mirror we have to protect mirror from them, it can be done by magnetic fields - which can be a challenge by itself.
Thus the mirror isn't an easy option, and sucsess is highly depend on successes in technical development, testings etc - it might fail in 10+10years plan, or do not achieve good enough results, and with necessity to refurbish the surface of the mirror in such not an easy environment is fragile and technologically hungry solutions, so even if it may be a part of a self-sufficient solution, we may choose another approach which requires less maintenance and which is less technologically advanced.
But first of all the energy, how much of it we may produce and use at that distance.
## Energy
Despite abundance of energy at this distance(10 million km) solving the problem of electricity generation may be not so easy, because of energy density of the solar flux, solar wind, it isn't just as simple as plug solar panels and you are in the game, specially as a long therm solution.
It will have the same problems as mirror solution for the bottom of the station, erosion and degradation, and same protection from solar wind plasma needed. [Multilayer cells](https://en.wikipedia.org/wiki/Third-generation_photovoltaic_cell) have around 40-50% efficiency (up 64% theoretical, at the moment, according wiki, I heard 70% efficiency)
But as multilayer they may degrade faster then usual cells, specially so close to the Sun which is a strong gamma and neutron source. How much energy they need to be produced, how much energy they may produce in their life time, will it be enough to renew them in this environment, specially with small station production capacities. Who knows. Development of technology isn't so easy to predict.
But those efficiency's are not way too far from electricity generation with steam power, and solar cells just do not work at temperatures where steam generation works. So this way we will go with 40% efficiency, good enough. No need in super duper technologies for to repair and to produce.
Thus as the electricity generation device we choose a steam turbine, was good enough for my grandpa, good enough for the space.
With 300-340K of side surface of the station, it means 460-760W of the waste heat can be dissipated with each square meter of the surface. With above given parameters of the station, we have 5-8 GW in form of electricity. Which we have to spend some where outside of the station(for propulsion as example). More realistically 3.3GW at 300K (waste and electricity(which will become waste after some use) combined, electricity will be something like 1.3GW here)
* there may be another ways to generate energy so close to sun, as example using solar wind(plasma) directly to generate potential, also use photons to accelerate electrons and get energy from them (reverse [vacuum tube](https://en.wikipedia.org/wiki/Vacuum_tube)) and such solutions may work entirely at 1500K (or 1260K actually, because 2 sides irradiate heat). Some materials will form plasma at such circumstances, and just that fact is enough to get energy. These solutions, as they may work in that environment without need for additional cooling, may solve energy and heat problem for station completely(at that orbit). As we have energy, we may cool station, specially in case where energy solution is also heat dissipation-protection solution. But such solutions have to be tested, perfected etc - and how much time it will take, no body knows.(depends). So without smart technologies, like this one [Laser Wake Field Acceleration](http://www2.mpq.mpg.de/lpg/research/LWFA/LWFA.html) but for our needs at that orbit and without lasers, and and and ....
* But needs to say -- the station may potentially operate with significantly larger amounts of energy then just 1.3GW of electricity. In given situation with steam it can be 15GW, if side surface works as a radiator at about 650K(cold end for steam). Usual hot end for steam is about 823K, so efficiency will be pretty low about 21%, but because of black body emission is proportional to T4 it maximizes electricity generation.
## Heat
* usually people are concerned about that more then it needs actually, and I'm perfect example of that with this kind of answer.
With ratio 1:14.3 we can't just take all energy at bottom and dissipate it, our optimistic dissipation capability with 400K (above boiling point of water, and we still may produce energy at that point) is 10GW in form of heat. Bottom gets $\approx$ 15 times more, so our abilities to dissipate are 6.6% of what we may potentially have to dissipate.
There are good news too
* there are lot of material with melting point above 1500K, Specially Fe, Si, SiC, C, and pure SiO2 with it's almost 2000K.
* zero gravity - we may have just molten ball at bottom of station, as shield(reducing flux) - I mean structural strength of materials is not big issue here.
* we no not need some rare and unique materials
Black body surface, with 0 heat conductivity, will have temperature 1500K on side of sun. But some sheet of material heat conductive, will have temperature 1261K because it emits energy to sun and from sun - so just plain sheet at bottom of station, will reduce energy 2 times.
Sphere will dissipate energy all around and will have temperature 1060K, 4 times less energy(approximately, visual angle of the sun isn't counted here)
But lets take look at that cone station(r=400m, h=5720m), and If it will be kinda solid, will it have equal temperature on all over it's surface. No, because of heat transfer rate in the material of the cone. So less heat conductivity will be, more will it be the difference between hot part(base of the cone) and cold end(the tip of the cone).
[Space Shuttle Thermal Tile Demonstration](https://www.youtube.com/watch?v=Pp9Yax8UNoM)
This demonstration is good, but eventually any material used for insulation in furnaces will work same way(I mean for needs of the station, not in this kind of demonstrations), just a layer of the material have to be ticker. But we do not need that layer be thin, more then that, we explicitly wish it to be tick enough to stop gamma rays, neutron flux, solar wind, this way thicker it is better is it and for thermal protection and for other types of protection.
So we may take good enough amounts of a material from the mercury, which is near by. SiO2 stuff on top, Fe bars as structure keepers, and heat conductors in perpendicular direction(this way heat conductivity of shield will be more in radial direction and less in axial direction). Ticker it is for longer it lasts, better it is as protection against high energy electromagnetic waves and particles, less energy transfer to "cold" end where people are.
First layer acts as brute force, as heat dissipation system, as filter for spectral energy(cuts everything with short wave length gamma, UV etc).
As next layer it may be used something more valuable and suitable for heat protection at lower temperatures, there are lot of solutions to use, they are not space grade(yet), but first layer isolates (if solutions need that) from space - and converts the question: how do you would survive and build station in such hard environment, in to the question: how do you usually protect furnaces and workers.
As example
[Thermal conductivity](https://en.wikipedia.org/wiki/Thermal_conductivity#Experimental_values) of steel is around $92 \frac{W}{m \cdot K}$, SiO2 $8 \frac{W}{m \cdot K}$, basalt-glass $1.2 \frac{W}{m \cdot K}$
We know hot end temperature(1500K), as we steam energy generate, we know cold end temperature 818K(545°С) which is hot end for steam system, we know how much energy we may dissipate 10GW(at boiling point of water and this energy is equivalent to the energy flux from hot end to cold end in the heat shield) and it is something around 20$\small kW/m^2$ at bottom for station (r=400, h=5720), so we may say how tick this bottom have to be for different materials.
$P=-\varkappa\frac{S\Delta T}{l}$, $l=\varkappa\frac{S\Delta T}{P}$
for material with $1 \frac{W}{m \cdot K}$, only 0.034m, or 3.4cm tick - woow that's unexpected.(basalt wool is used for insulation)
For steel it will be 3.15m tick.
If we do not generate energy and just dissipate energy at 300K at side surface of the cone we have to consume less energy from the cold end of the shield, so thickness have to be ticker about 3 times roughly speaking(3 times less energy, 3 times ticker bottom).
Considering the fact we have to have ticker radiation protection layer then for heat protection - heat protection isn't issue after all.
## Conclusion
There are lot of challenges in building such a station, but heat alone is not an issue. For those who thinks about ISS heat dissipation arrays, coolant there is NH3 and temperature at which heat is irradiated is 240-200K. Two times difference in temperature means 16 times difference in power of irradation.
Another big challenge is getting lot of materials to some point where station have to be build, but for 200 peoples station do not have to be so big, all parameters scale well with base surface area. For 200 people at the station it needs something like 20kW per person - for food, technical needs etc, so cone dissipation energy have to be 4MW or roughly 750 times less then the same in the bigger station which was used above as example. It means surface of base have to be 750 times less, so it will be a cone with parameters (r=14.6, h=208m) volume 46406 $m^3$, it is not much a volume per person so it have to be bigger then that, just to be able to place all needed equipment for recycling, maintenance of the station etc. So energy isn't a limiting factor here, and it is more a question about technologies and equipment and sizes and volumes needed for it, for food production, process waste, production lines needed to make repairs in station in- and out- side.
As my opinion we talking at least about 100'000 tonnes of mass (average density 1$\small t/m^3$) and + another 100000 tonnes for shielding, mostly for radiation protection (I think 30m layer may be good enough)
There are ways to solve different parts of the problem, but OP information and 10+10 plan isn't good help here.
But there is nothing which can't be solved by 1000000 launches from Moon or from Earth.
There are other and more reasonable ways to build the station, but looks like OP is about another apocalyptic situation, so one rocket per 7 million peoples each day in next 3 years and station will be done.
7500 m/s delta from earth to mercury, after that solar sails, ION drives with higher ISP and down to 10kk km to the Sun.
Better approach would be establish production base on the Moon, and lift the stuff with [Non-rocket spacelaunch](https://en.wikipedia.org/wiki/Non-rocket_spacelaunch).
And the station may be assembled entirely on the moon and be launched from the Moon. Or it may be assembled in L1 point with other constructions we may wish to assemble there.
Is 10+10years possible, with current tech - yes, definitely. And most important tech from them all is our ability to automate tasks.
Will we have such station in 20year, not sure, I do not see any sense at the moment in doing that, but if I do not forget about it for fun or if scientist's will say they need such station - then sure, why not.
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Many authors and worldbuilders swear by the space-navy organization scheme:
* Frigate - a light vessel used to enforce borders and partol
* Cruiser - a flexible vessel that can operate independently
* Destroyer - a light vessel tasked with taking down incoming threats
* Carrier - a specialized vessel that carries and deploys smaller spacecraft
* Battleship - a heavy vessel with huge amounts of firepower
* Dreadnought - a very heavy vessel, often acting as flagship
But this classification scheme is built around the needs and characteristics of a wet navy.
Assuming a realistic-ish setting (around [4-6 on Mohs scale](http://tvtropes.org/pmwiki/pmwiki.php/Main/MohsScaleOfScienceFictionHardness)) where FTL travel is either not possible or is only achievable by a vessel through outside means (a wormhole or FTL warp station). In which militarized spacecraft are commonplace, as are space engagements, and without a clear bias to either kinetic/chemical or energy weapons. What kinds of classifications for spacecraft could be expected to crop up (hand-waving actual names)?
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Rocketpunk Manifesto looked at this question in a multi part series of threads about Space War (<http://www.rocketpunk-manifesto.com/search?q=space+war>), and the results were not quite what you would expect.
First off, space warcraft are defined by their roles much the way wet navy ships are, but since the roles of spacecraft are different , so are the names. Formations are also different, so there is quite a bit to cover.
First off, because ships are constrained by orbital mechanics, their paths are fairly predictable. IF you are doing a burn to a transfer orbit to Uranus, then there is no "sneaking away" to reach Mars unobserved, you need to apply a lot of energy to get to different transfer orbits. This is true even using Terrawatt powered Torch Drives (although in this case, you are already radiating enough energy to be clearly visible out to Alpha Centauri).
So ships will travel in mutually supporting formations known as "**Constellations**".
Within the constellation are ships carrying massive laser weapons, the most powerful the polity can afford to build and field, since long range laser engagements work in the favour of whoever has the greatest range. For practical reasons, this means building lasers which can vaporize metals and ceramics out to the range of one light second (almost the distance to the Moon from Earth), since beyond a light second there is a significant lag between when a signal arrives at your ship, and when you point and fire the laser. The enemy ship can apply some random thrust and ruin your fire control solution. The laser weapon is colloquially known as a Ravening Beam of Death (RBoD) and the carrying ship is a **Laserstar**. To make targeting the Laserstar's optical train more difficult (an "eyeball frying contest"), secondary **Fighting Mirrors** might be deployed remotely to make tracing the possible optical paths more difficult.
Supporting the Laserstar is a fire support ship which carries thousands of small kinetic energy projectiles. Swarms of these projectiles can eventually overwhelm even a massive Laserstar, but we are talking about thousands to tens of thousands of projectiles filling the sky. Such ships can use railguns, coil guns or simple batteries of rockets to launch the small projectiles, colloquially known as "Soda Cans of Death" (SCoD). The secondary purpose of these devices is to fill the sky with swarms of sensors to provide a fine grained 3 dimensional view of the battlespace. These ships are known as **Kineticstars**
Laserstars and Kineticstars are mostly unlovely assemblies of girders, power plants, fuel tankage and radiators, and rely on powerful AI's to ensure their weapons are employed to the best effect. However, these weapons are far too powerful to be allowed to go off on their own, and are massive overkill for many of the lesser missions that a Space Navy might be assigned. A manned **Command and Control ship** is needed for the constellation, to provide the human staff which gives the final authority for fire/not fire to the AI's.
Since some missions actually require boarding parties to inspect ships, the constellation will also need **Cutters** to bring inspection teams to and from the formation. Armed and armoured cutters might be included as **Boarding Craft** for the Space Marines, and the Admiral will also have a **Lighter** to travel on diplomatic or courtesy visits, leaving the constellation in high orbit to "show the flag".
Various miscellaneous **Support Ships** will be included in any constellation, to provide berthing space for the smaller craft, repairs for systems while under weigh and recreational space for the crews outside of their fighting craft. For practical reasons the fighting craft will be very small to reduce their signatures during the fight, and they will disperse among the ships and sensors of the deployed constellation in order to maximize their survival.
A fully deployed constellation will be incredibly impressive. There will be a swarm of sensor drones and subsidiary gunships (smaller laser and kineticstars to provide close in defense) spread out over a light second in diameter, with the massive Laserstars and Kineticstars deployed inside this disc. The Command and Control craft will also be somewhere inside the disc, to provide oversight to the deployed weapons systems, while the support ships will drop behind.
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I feel like the rules would absolutely change for naming-schemes for space-faring vehicles. I guess it would all come down to the usage of those vehicles. For instance, X-Wings/Arwings/Tie Fighters are used in dogfighting, while their counterparts are used in scouting, bombing, transport, etc. I think it stands to reason they could still be named (both officially and affectionately) based on either their amount of firepower or maneuverability. Other potential factors would be crew size or where the ship is flying. But then you gotta ask what that means.
**Maneuverability** - can it move 360 degrees? can it move fast? does it move at the speed of light (or approaching)? Does it hold more than one passenger?
**Firepower** - can it destroy asteroids? can it destroy other ships? can it destroy space stations? can it attack a planet's surface from orbit? can it destroy planets? does it have its own orbit?
**Crew size** - is it a single pilot? Co-pilots? A crew of 10? 100? 1000?
**Destination:**
- orbital (only functions properly within a planets orbit)
- transorbital (functions both in and out of a planet's orbit/suborbit)
- interplanetary (travels between planets)
- interstellar (travels between solar systems)
- intergalactic (travels between galaxies)
Leads me to think maybe those could be the derivatives of the designations. But honestly, even looking at aircraft, most planes are named after and referred to by brand and manufacturer (Boeing) or designation (F-22, B2) etc. For instance, the "Musk IP-48" interplanetary transit craft, designed and manufactured by the Elon Musk Spacefaring Corp.
Alternatively, I'd like to think it's still reasonable to assume classifications could very well be almost identical to that of the naval vessels. But with names more suited to tasks in space. Examples:
* ~~Frigate~~ **Defender** - a light vessel used to enforce borders and partol
* ~~Cruiser~~ **Wayfarer** - a flexible vessel that can operate independently
* ~~Destroyer~~ **Fighter** - a light vessel tasked with taking down incoming threats
* ~~Carrier~~ **Transporter** - a specialized vessel that carries and deploys smaller spacecraft
* ~~Battleship~~ **Challenger** - a heavy vessel with huge amounts of firepower
* ~~Dreadnought~~ **Station** - a very heavy vessel, often acting as flagship
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Assuming from this you're going to be starting from a real-world background if you're limiting FTL. From that perspective, it should be important to note a few things...
U.N. treaty prevents weapons in space, and initial pioneers would have no reason to ignore this convention when survival means working with your fellow colonists and infighting could destroy an early colony.
So not only would navy terms be unlikely, but considering most of the other colonization places in the solar system don't have oceans, it'd be downright ludicrous for that tradition to stick around.
Also, the idea of a "fleet" is somewhat silly in space-based combat. There are physics problems that limit the ability to make everything one ship or as many tiny ships as possible for ocean-faring. With space, the only limiting factor in that regard is gravity which isn't a big issue until some ludicrus sizes (at which point it might be considered nice and give a more habitable region to the ship.) Also, in-space debris collisions can be fatal so you'd want to consolidate to one vessel as much as possible except when having as many small points as possible is preferable (such as swarms of fighters). Further, due to mathmatic laws of scaling up, you can protect more volume with less surface area by scaling up, meaning you get more shields for your buck using one large vessel.
At this point, seperation of vehicles comes from physically separated purpose.
Here's my thoughts...
* **Mothership** This is THE ship of the fleet. During normal traveling, probably the only visible vessel. Probably have the term mothership because even if ocean-faring isn't common, people are still going to have videos and movies, and the term fits. Due to being a larger target, whether or not energy shields exist to make defenses reasonable against a concentrated attack, if energy shields don't exist, a mothership may only exist for transporting everything and holding command staff. Basically being little more than a very tiny ship connected to a very massive hull that serves as a "warehouse" of sorts and some engines to move everything.
* **Swarms** are meant to maximize effective surface area for spread across space while using minimal mass/volume/interconnectedness. This would be swarms of drones, fighters, etc. Realistically, due to a lack of interference in space, wireless communication makes more sense than wired, as "direct hits" on multiple weapons don't risk the main body, are easier to replace, etc. Swarms could be sub-divided into roles,communicating with eachother using an encrypted short-range wifi, bluetooth, or similar. The size of the swarm would likely be limited by the range of communications. Swarms with specialized purposes might have specialized names as well. This is a generic swarm.
+ **Command Drones**: The central node (if pilot is on mother ship) that tight beam communication is with, probably most heavily armed of bunch.
+ **Repeater Drones**: Probably more heavily armed than Soldier drones
+ **Soldier Drones**: The "foot troops" of a swarm. Little bots that are little more than an engine, gun, and data receiver.
+ **Pollies**: Short for "Pollinators". In swarms specialized in fetching things, basically claws with a receiver and an engine and some slightly more advanced communications and able to go outside of normal swarm range. Probably primarily fetches asteroids to be used as Rocks and to fetch from "tulip fields" (which would look like bees pollinating, hence the name.)
+ **Stinger**: A drone that's just an explosive, onboard computer, and engine. It's a one-use weapon, meant to detonate on an enemy. Other potential names include "Kami" short for Kamikaze after WWII japanese pilots (likely *not* used by pilots of Japanese decent since Kami actually means a god. But those of American decent probably would.)
+ **Queens**: So a "fighter pilot" might either be actually in the mothership sending signals to a command drone on tight-beam who communicates
with it's surrounding swarm, OR they'd actually be in a small command vessel; either way "piloting" their group like playing a real time strategy game. If their own vessel, fitting with "swarms" and "drones" being fitting titles for those, it seems inclined to go with a hive motif and they'd probably end up getting called something like queen bees. In typical shorting fashion, probably eventually getting reduced to just queens. (If the machismo is still strong in society, they'd probably switch it to Kings, King Bees, QBs, KBs, Qubes/Kubes, etc.)
* **Tulips and Tulip Fields**: A specialized dumb AI swarm that's an array of solar panels for catching solar power and storing batteries. Probably tries to stay out of actual combat, only commands are *head out* and *come back* but provides energy supply. Since their job is "sit there, charge, and give batteries to pollies" they probably don't need any command nodes, just an encryption system for when pollies ask for batteries to release them (likely replaced with a dead battery the pollie is carrying). So named because of colorful solar panel "petals" in flower-like patterns from the central charger body.
* **Rockets**: Despite conventional rocketry will probably fall away, the concept of "get it into space fast with its own engine" will probably result in rockets still being the preferred term. Used primarily for fast small strategic and expensive strikes since energetically they're so expensive, usually containing small groups of marines/stormtroopers. Mainly launched from planets and gravity wells. However, due to the similarity of ride and intent on speed, more common ship-capturing troop transports may also be referred to as this.
* **Chutes**: Short for parachute. Named for the last stage of dropping down to a planet with an atmosphere (although for other planet types, may not actually deploy parachutes). Meant for getting lots down to planet cheaply.
* **Lines**: Portable space elevators (little more than a loooong spool of high-strenght cord and a solar-powered robot that can climb it). Meant for long engagements with a planet to establish a reliable and effectively cheap transport system between mothership and planet capable of high volumes. These are for establishing supply lines. Due to the fact they'd look like a vertical line drawn from the ground, be the primary supply lines going both directions, and have to be guarded like a traditional supply line in modern warfare, providing the "lifeline" back to the ship for ground forces, the more preferred terms for space elevators (elevators, tethers, cables, liftports, etc. likely more established ones for civilian uses) would probably give way to the term "lines" for military uses.
* **Rocks**: Pretty much what they sound like. Big dumb hunks of mass carried by the mothership for dropping to a planet for planetary bombardment. Since gravity would turn a dumb rock into a nuke, and all you have to do is aim right when you launch, it'd be fairly straightforward. Likely ship's unusable waste would get consolidated into a few rocks. After that, you'd probably have a few dense blocks on board for that purpose or have swarms designated for grabbing asteroids.
* **Crisses**: Short for "Crystal Beams" due to the appearance of flickering crystal-like look and light scattering making slightly visible beams. A specialized computerized swarm. Why power your own weapons when a star can do it for you? Very little user input other than positioning and targeting since everything else is just calculating angles. It's a swarm of drones with Fresnel lenses to direct sunlight at a specific point (like multiple magnifying glasses aimed at the same bug, but on a much larger scale).
Fleet appearance:
[](https://i.stack.imgur.com/WbVjv.png)
*Notes: Edited-in design thoughts* Since it makes more sense to have a single large mothership until it exerts enough of a gravitational field, but fleets are likely to be expanded, and objects that have give usually being able take more punishment than those that don't, Mothership exteriors are likely to modular and flexible like a mesh bag. The flexibility lets its shape naturally adjust to increased sizes as its modified, modularity makes it easy to repair and expand. I can see this being implemented multiple ways, and a mothership could help launch smaller ships with its own engines abusing centrifugal motion - spinning to send them flying. Being flexible, there's many ways the mothership could be used during combat. If command staff are all on the mothership, it could retract and collapse in, providing denser armor for the mothership. It considered too valuable to be present and swarms are controlled by queens, it could "deflate" and retreat to either help after-battle cleanup or keep high level stuff (command staff, manufacturing plants, etc.) safe in case of loss. Alternatively, if the way they organize, it's basically a dumb bag shield when empty, it may provide cover. If modular enough, it may even break apart and provide attached shielding to command pods of swarms. As an additional idea, the mothership could primarely *be* the swarm if the swarms are built to withstand high-speed travel pressures. At which case, the "mothership" may be more of a skeleton that all the swarm ships latch onto, the most externally mounted swarms being the most shielded and providing another unique combat swarm with heavier shielding. It really depends on the design preferences at that point and mentalities of the militaries involved and their tactics styles... are they more offensive/defensive, more hierarchically minded or more equality minded. Also, since you could expand until you have gravity problems, you'd likely never have multiple motherships near eachother because complex gravity interactions can cause all kinds of problems in a skirmish. Shrapnel alone will be a nightmare to navigate, but that's less avoidable. As such, Motherships will likely never be in close vicinity.
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The answers depend on the kinds of engines that are available for ships. If it's possible to make small ships that are a lot faster than bigger ones and have a few hours of endurance, then you end up with something that takes the role of aircraft.
If it's possible to make small craft that are really fast for a few minutes, you have missiles.
If all spacecraft have similar performance, to with a factor of three or so, you get something that's a bit like a wet navy without aircraft.
Then there's the cost. Military forces tend to end up buying whatever they think will give them the most combat power for their budget. So it depend on how combat power and cost scale with size. If combat power goes up faster than cost, you get big ships. If not, you get small ones.
So there's no one answer on your criteria: you need to define a few more things before there's a logical answer.
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## C-K-35M
Type: Civilian, possible type Military, Hostile, Neutral, Alien, DS(almost stationary object, earth is DS-HK-63)
Size units: km. possible units cm, m, dm, hm, dkm, hkm, kk, mk, au
Size: 28 km radius. 2 digits value.
Capability's: M - can morph,
`Death Star` M-DK-16
`TIE Figther` M-M-6
`StarFury` M-M-10
`X-Wing` M-M-12
`UNSC Pelican` M-M-30
`Millennium Falcon` M-M-30-FTL
`Endurance` C-M-65
`ISS` DS-M-73M
`Discovery One` U-M-140
`SSV Normandy SR-1` M-DM-16
`Enterprise NCC 1701` M-DM-29
`Whitestar` M-DM-48
`UNSC Frigate` M-DM-49
`Enterprise NCC 1701-D` M-DM-65
`Destroyer` M-DM-90
`Romulian Star Empire` A-HM-14
`Galactica` M-HM-15
`Covenant battelecruiser` A-HM-19
`Collector Cruiser` A-HM-19
`Destiny Ascension` AN-HM-19
`Reaper` AH-HM-20M
`Droid Control Ship` H-HM-32
`V Mothersip` AHN-HM-32
`Apophis` AH-HM-34
`Hel` M-HM-43
`Dictator` M-HM-51
`Covenant Assault Carrier` A-HM-54M
`Anibus` AH-HM-55
`UNCS infinity` M-HM-56
`Borg cube` AH-K-3
`Lexx` AF-K-10M
`Eternal Crusader` M-K-10
`Collector Base` ADS-K-12
`Avatar` M-K-14
`Erebus` M-K-15
`Mass relay` ADS-K-15
`Ragnarok` M-K-19
`Executor` M-K-19
`City Destroyer Invasion Mothership` AH-K-24
`Citadel` ADS-K-45
`TET` AH-DK-10
`Death Star` M-DK-16
`High Charity` ADS-DK-47FTL
`Death Star 2` M-DK-90
`Halo` ADS-DK-42R
`The ark` ADSM-KK-128
[source of ships](https://www.youtube.com/watch?v=m_Loc7qX7FI)
Looks like viable classification for me.
Once you really need is to decide run, fight or ignore in your situation.
Capability's are by size and advance. But same tech level can be easily refereed-compared by size. For tech you own, you may estimate own technological advance, compared to any known tech.
As it may be seen by that list, fixed name classification do not gives needed flexibility. And at some, and I may say not super advanced or even advanced level, fixed classification have not sense, and is too inaccurate.
Most time size, specially internal volume determines how much energy you may deliver or how much energy you have to use to move ship.
Definitely it can be cases, when this classification will not work, but harder is Moss, more sense it have.
## Clarify
* classification is based on size and relation with the target.
* gives important tactical information in short way
* able to classify unknown, never seen before objects, just out the box
* is practically enough in accuracy - to make descision
* is able to classify 1000+ unique constructions, which may be important if let say space civilization will be bigger then earth let say in 100 times. There will be 100 times more unique constructions as example. and 95% even no sense to give personal names, like Tsar Bomba, or Satan. 95% of them will be no name vessels, usually no body cares about.
* For civilian ships usually important how much it may carry, what type of cargo it intended to carry. They all have project names or number - no body cares, at first look.
* We have limited amount of military ships, we have luxury to give them names, pet them with 6 category classification, which means nothing except size and firepower and type of that firepower. In case millions of ships, 100 thousands types-constructions. It's like old guns with ornamentation and names - do have to days guns names and ornamentation, no, just type and size of projectile.
* Ship may change it's size, and have one principle - have it to be classified by something like name, it have same ID number, or by current state of it. It's just a target, you have to know can you destroy it or be destroyed by it or not - that's all.
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In this world Humanity was wiped out, all that remains are several small groups of genetically altered human chimeras. These new "humans" have a genetic cast structure similar to that of hive insects where 70% of all children born are infertile females (think worker bees), 20% are fertile males (think drones), and 10% are born as fertile females. The fertile females are capable of releasing hormones that allow them control over the infertile females and fertile males (think honey bee queens).
Since each village or colony will only have one or two queens, each queen would have to be capable of producing many more children than regular human women do.
I have increased the birth rate by saying that they are genetically altered to have a much higher egg count and therefore have menopause at a much later date and can have children up to their old age. However, I'm not sure this will be enough to keep the colonies' population going.
What other alterations to the human genetic code could I add to the queens?
Ideally, I want a colony of a 100 people to be supported by only two, maybe three, queens.
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Look at a queen termite compared with a regular individual. Imagine the worker is a normal human size. That makes the queen a sprawling snake of abdomen that fills the room! She would be immobile, and have workers feeding predigested pap on one end (she could not digest enough food on her own) and removing waste on the other. The extended abdomen would hold rows of wombs in various stages of gestation.
Horrific and monstrous for a story, for certain, especially if the hero finds out at the end and that his fate is to mate and be eaten. But not at all realistic for a creature our size.
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If you want a more modest number of offspring, you can increase the lifespan of the lifeform. The worker population can be built up slowly, and seldom need to be replaced because the workers live long, too.
Each queen can have multiple pregnancies at once, but similarly to what human women can do in real life, like twins or triplets. If the workers could be born earlier and then be cared for by others, not only does it make multple births more practical but it shortens the time needed for each litter.
For example, if a queen produced 4 workers every 10 months (7 for gestation and 3 to rest between) for 100 years, 120 batches of 4 is 480 workers.
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Note that this is also a limit on the kingdom size! The workers have a limited lifespan too, due to age and accident. If the lifespan is the same for workers and queens, then the replacement queen will replace workers and not add to their number.
Note that this has serious reprocussions for recovering from a disaster or disease. Workers lost early can't be replaced as new births only cover *normal* loss!
So this doesn't seem like a workable solution. A colony must have a queen that can produce many workers quickly.
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Let's establish some things:
You say they can bear children when they are older, so lets say they have children from 20 to 60 years old, a 40 year production time per queen.
Let's say their menstrual cycle is a lot faster than today's, so the queen could get pregnant any day (or at least any week) of the year.
Here's some ideas:
1. **Faster growth**—the mothers pass something to the babies something in the womb that dramatically stimulates cell reproduction/growth. The babies could pop out in 2 months, instead of 9. Women could have 4-5 children in a year. Say 4 per year for 40 years, that's 160 per queen.
2. **Faster output despite lack of growth**—currently a baby can't be born prematurely that well (lots of complications). Say in your world they have a way (artificial eggshells or something) to allow the queen to give birth way prematurely, and the baby doesn't die but is cared for outside the womb.
3. **Genetically have twins/triplets a common thing**—Some people are genetically predisposed to this: A woman named Mrs Vassilyev supposedly popped out 16 pairs of twins, 7 sets of triplets and 4 sets of quadruplets in her life, 69 children all up (no single child births at all).
4. **Creepy options**—You could massively change the physiology so the queens have multiple wombs, making a kind of gross child factory like the termite queen answer. Or you could make the queen huge, with a giant womb that holds a few dozen babies at once, releasing them [seahorse style](https://www.youtube.com/watch?v=uKrkXXaRMUI)
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There is a real world mammal that has a queen and caste system similar to what you describe: the naked mole rat (Heterocephalus glaber). [BBC wildlife videos about naked mole rats](http://www.bbc.co.uk/nature/life/Naked_mole_rat)
To turn a human woman into a naked mole rat queen who can have big litters of babies, you need to sort out the human pelvis and/or the human baby. And possibly the human placenta.
**Pelvis**: birth is difficult and prolonged because of trade-offs between walking bipedally and having a big brained baby. If your queens are practically immobile, and just lie around all day (like a termite queen or naked mole rat queen), then the pelvis architecture can be changed drastically. Wide enough to squirt out the babies without much effort.
**Human baby**: alternatively, make human babies much smaller and even less well developed than they are now. So instead of an 8 lb baby, the queen has several kitten sized babies (8 x 1 lbs), for the same 9 month pregnancy. The 'factory settings' for the mammals is 8 nipples, and some beasties have 16, so the queen can have multiple babies nursing at once. Or, she passes them over to the infertile females to breast-feed.
**Placenta**: The human placenta is directly bathed in the mother's blood. This is very efficient in getting nutrients out of mum's blood and into baby's blood (only 3 layers of tissue to pass through). The downside is if something goes wrong, mum can bleed to death. If mum is producing 8 to 16 babies at once, I guess that risk goes up as she has 8 to 16 placentas? So perhaps the human placenta could be re-engineered back to the 'primitive' mammalian state of 6 layers of tissue:
baby's blood - placenta 1 - placenta 2 - placenta 3 - mum 1 - mum 2 - mum 3 - mum's blood.
Much less efficient, so development of the foetuses would be slower.
Meanwhile, **menopause**. Menoapuse isn't just about egg number, it is about nutrition and how much hormones you have squirreled away in your body fat. The average age for British women hitting menopause is [51 years old](http://www.nhs.uk/conditions/Menopause/Pages/Introduction.aspx) whereas subsistence level farmers the average may be as low as 42. So if you feed your queens a high fat diet, they can have a longer reproductive lifespan. (Possibly. Some of this delayed menopause is an ability to still having periods, even though you've run out of eggs.)
How many babies they'll need to have will depend on mortality in your society. If 50% of kids die of childhood diseases or get eaten by bears, the birth rate will need to be high to keep the population stable.
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**Goal**
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The goal is 100 people. Based on your statistics, there would be 10 queens born (but not necessarily living to maturity), 70 worker females, and 20 males. As a result, after hitting this population level each queen would need to produce 10 children. Call it 15 for proof against statistical anomalies, power struggles, and bad luck. 15 kids has been achieved in the real world, although not (to my knowledge) as part of a sustained society.
Also, that's boring.
**Ideas**
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Here are some suggestions if you'd like to try for two queens per colony (50 kids per lifetime).
* Fertility window: Real women can only reproduce a few days a month. Find a way to keep that ovum alive to increase that window, preferably indefinitely.
* Multiple births: If every pregnancy is twins, you've just doubled your birth rate. However, it's likely riskier for both mother and children.
* Ova production: My understanding is a real girl is born with all the ova she'll ever have. Tweak that to produce indefinitely, as men do, to get fertility from puberty on. Bonus: splitting one cell into two ova gets you two genetically distinct twins.
* Anatomy: Childbirth is potentially damaging to both mother and child. Structural changes to the birth canal might make this process less damaging and thus more sustainable.
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Make the queen a marsupial. She "births" her children into a marsupial pouch where they can be better protected as they grow, then she has a free womb for impregnation again. She can pass off the older newborns (joeys?) to sterile females for child care as new ones are born. Obviously this would require some significant changes to human fetal development to emphasize the ability to suckle, breathe air, digest milk, prevent infection and excrete waste first, versus the more advanced brain development a human gets prior to birth. But it would allow a human(ish) female to potentially give birth to many more children (and more importantly, a constant stream instead of a large bolus like an octomom situation).
So the embryo gestates in the womb for, say, 3 months, then lives in the pouch for another 3 before being large enough to be cared for by another at 6 months. That would allow a queen to have 4 young a year, an almost 4x increase over normal human women, with almost 150 births over a normal human reproductive life (13 years to 50). This wouldn't require massive changes to how humans develop or retain fertility and could be further boosted with twin deliveries or delaying menopause another decade or so.
On a side note, most queen based insect colonies have the ability to transform a female worker larvae into a queen. How this would work in a marsupial based birth system would be tricky. Loss of a queen would immediately terminate all her young that couldn't survive on their own, presumably it would be too late at that point to "promote" a sterile female worker newborn into becoming a queen via diet (aka "royal jelly") since the sex organs and whatnot would have to be present from a very early embryonic stage. Perhaps a surviving queen could choose to secrete special milk that promotes a female joey into becoming a queen, maybe she normally secretes milk that PREVENTS joeys from becoming a queen (so all embryos could be queens, then they lose that capability via a process that occurs while in the pouch) and that changes if there are no other queens around (kind of how coyote females boost egg release as the pack gets smaller), or when being a queen is just a low incidence mutation that only occurs in 1-2% of births so they kill it if it is not necessary or drive her away at puberty so she can found a colony elsewhere. Point being, the colony is VERY dependent on having an existing queen as it is probably very difficult to produce another one. So either a queenless colony raids/trades for another colony's queen (presumably an immature one) or they start to die off. Perhaps this process is what allows for genetic diversity between colonies (similar to "wife stealing" in many tribal cultures).
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Does the queen have to bear the children? Or can she simply do something to make the infertile females fertile? Somehow implant a fertilized egg in them, or somehow cause them to ovulate? That way the queen is in control of reproduction, but isn't required to bear all the children herself. This could wind up being handier, since in case of some disaster that depletes the population, the queen could quickly have multiple children "in the pipeline" as it were.
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You don't necessarily need any crazy mutations, lets compare to real life situation:
In Finland there is a religious community where it is not allowed to use any birth control. The average number of children is around 10, having 15 children is not rare and I know families that have 19 children. Restrictions are, they get married around 20 years old and are fertile maybe to 45 yrs.
So lets say a modest approximation one child every other year and change other restrictions. If your queens are required to start reproducing at age 15 and as you say they are fertile longer, lets say to 65, that's 50 years fertile = 25 children per woman.
If you either have always twins or have a child every year, two queens would make next generation 100 people. Since you only want two queens in each generation (if I understood correctly), 100 is more than enough, which allows you to alter the fertile years or amount of twins or how often the children are born, whatever suits you best.
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A big dog is the same size as a small human. Dogs have a gestation of 60 days (compared to human 270) and routinely have multiple births. Metabolically and physiologically there is nothing wrong with that for a different big animal: the human.
**The reason for long gestation likely has to do with post-birth selective pressure, not needs of mother or fetus during gestation.** For humans and other primates there is a huge maternal investment in each child: both before birth but especially afterwards. It is very possible that long gestation has nothing to do with the fetus being gestated but more to do with time between live babies. If you are the only baby you are more likely to get all the mom resources. If you have siblings 3 and 6 months older they will outcompete you for mom resources. Long gestation means your siblings are older when you come out, to a greater degree fending for themselves. So the genes leading to long pregnancy leads to greater fitness to those babies.
You have communal care by the workers so time between births is not an issue. You have genetic engineering so you can shorten gestation by asserting it is so. Likewise multiple births. It would conserve eggs if the multiple were not the result of different conception events (like fraternal twins or the Octomom) but identicals: the result of one zygote which then splits into multiples before developing into babies. This would also be a good story device because each litter of siblings could have a reference name with the individuals having a number with the name. Within the litter they would look the same but different litters would be different ages and slightly different genomic composition.
You then can and should make the Queen the optimal way for the story: a formidable 8 feet tall Venus of Willendorf or sprawling she-Jabba.
It occurs to me that having a random sperm for each baby will mix up your genome to a degree such that your weird pseudohuman system might not be stable / sustainable because of dilution from genes outside the system. It would make sense for the queen to be parthenogenetic: no outside DNA necessary. [Parthenogenetic lizards](https://en.wikipedia.org/wiki/Teiidae) are not asexual: the gametes are still products of [meiosis](http://www.nature.com/scitable/definition/meiosis-88) and so progeny are not buds or clones like a jellyfish would make. Note that the Queen does not have a Y and so parthenogenetic offspring will be female. The possibility of parthenogenesis does not mean obligately parthenogenetic: some reptiles (alligators?) fall back to that mode only when no males are around.
Some parthenogenetic lizards still need to mate to kick things off; they either recruit a male from a different species or another female performs the male role. You can go into this aspect more or less as appropriate for the tone of your story and your audience.
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The jackalope is a mythical animal of North American folklore described as a jackrabbit with an antelopes horns. It's a popular mythological creature in hill folk culture and it made me ask a question, why don't animals other than Ungulates commonly have antlers? Why would animals such as rodents, fish and primates evolve antlers? What conditions would support the addition of these features?
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A list of all of the Anatomically Correct questions can be found here
[Anatomically Correct Series](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798)
[Answer]
I'm guessing that jackalopes have pronghorn antelope horns, because both are American. Pronghorn horns get called 'antlers' because they shed part of them every year, but they [are not true antlers - scroll down to illustration of the skull.](http://hubpages.com/education/Pronghorn-Americas-speed-demon)
That's pretty much where my knowledge of pronghorn horn/antlers ends. However, I can tell you why hardly any creatures have deer type antlers!
Deer antlers are one of evolution's freak accidents. To make antlers, deer have hijacked the **wound-healing mechanism**. The deer use the same kinds of biochemistry and physiology that you or I use to form a scab after cutting ourselves, or healing a broken bone. The trouble is, this is ***incredibly dangerous***. Antler formation involves turning soft tissues into bone. If the process doesn't stop, first the antler, then the top of the deer's head, then the brain will be turned into bone. As you might imagine, having your brain turned to bone is ever so slightly fatal.
Deer have solved this in several ways:
1. You shed the antler. Switch off the biochemistry that's calcifying everything to bone and switch on the regrowth biochem instead.
2. You have structures on your skull called [pedicles](http://www.jakes-bones.com/2011/02/all-about-deer-pedicles.html) to keep those dangerous antlers the hell away from your tender little brain. Some types of prehistoric deer had ludicrously long pedicles, presumably because they hadn't quite finessed the timing of shedding. Sorry, can't find a decent image of those, but here is photoshopped impression of what [Dicrocerus](http://faluns-loire.pagesperso-orange.fr/mammiferes/artiodactyles/ruminants/Dicrocerus.htm) might have looked like. I don't think that's ancestral to modern deer, but it gives you an idea.
3. At some point in their evolution, deer swapped their antler growth from being under control of the wound-healing hormones to being under control of the sex hormones. I'm guessing this is partly so rutting and maximum antler condition are synchronous. But it may also be for the deer to (metaphorically) say 'Done with sex now, so get rid of this life threatening thing now, now, now!'
So evolution of horns. Dead easy. Everything from dinosaurs to rhinos have done that. It's evolved multiple times, so it can be expected to evolve again in the future or on alien planets.
Evolution of an antler which you shed annually - much more complicated, and may be a 'once only' thing.
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One of the major reasons for animals growing horns is for protection or fighting for mates, dominance, or territory. Alternately, they can be used for digging purposes. There are animals which are not ungulates who do have horns, specifically [Jackson's chameleon](https://upload.wikimedia.org/wikipedia/commons/thumb/1/12/Jackson%27s_Chameleon_2_edit1.jpg/1024px-Jackson%27s_Chameleon_2_edit1.jpg). If you had fewer air-based predators for your jackalopes to need to evade through speed, they might conceivably grow them for defense. Another non-ungulate is the [horned lizard](http://www.spirit-animals.com/wp-content/uploads/2012/09/Horned-Lizard-1024x768.jpg) which has both true horns (contain a bony core) and spines made out of scales.
I can't weigh in on why other species don't commonly grow horns, but there are at least a couple which don't follow the ungulate-only trend of horns.
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Compared to most body parts, horns seem pretty simple to evolve, being basically bone growths covered in keratin. They are often associated with sexual selection and intraspecific competition; while they can be used for defense against predators as well this does not seem to be their primary purpose (otherwise females should have the same horns as males, which is very rare).
It seems more likely for hares to evolve horns than rabbits, to fight off other males (though notably, the jackrabbit is actually a kind of hare). Hare's competition for females is *fierce* (since females are only receptive for a few hours every few weeks, the so-called 'March madness') and often involves multiple males pursuing a single female and fighting each other off at the same time. A hare capable of knocking other males around by swinging his head back and forth might have an advantage in these pursuits.
It seems unlikely that female rabbits or hares would prefer horned males, though, since horn-like growths are a common symptom of the papillomavirus (the disease that probably inspired the legend of the jackalope). This would decrease the reproductive fitness of horned males, which suggests that jackalopes, if they did evolve, would be be a highly 'rapey' species, prone to mating by force. In response to this, the female may develop horns of her own to fight off unwanted suitors.
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It seems unlikely that rabbits would evolve horns since they would be a large hindrance for tunneling and moving through burrows which are a rabbit's primary defense mechanism.
A hare may do so but you have to consider scale here, most predators on a hare are significantly larger than it. Dogs, big cats, etc. Could a hare even one armed with horns realistically fight one off?
Larger animals do develop horns as they are useful defensively and they are actually large enough to make use of them. For an animal like a hair horns would just slow them down when running and risk getting caught on things slowing them down even more.
The only way it might work is if you had fake horns that are designed to be abandoned and act as decoys. This is similar to the tails of some lizards. The idea is that when a predator strikes, you shove the horns in its mouth and then run away while it is confused. Equally if the horns got tangle you could abandon them and again hope they distracted the predator. That's a lot of effort expended to grow the horns for very little win though.
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Interesting fact, there's this common virus called Shop papilloma which causes temporary bony tumors to sprout from the skulls of rabbits. It's thought this is the origin of jackalopes.
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## Scenario
America's issues with the Mid East are less pronounced due to a series of events, allowing it to focus on domestic issues.
## The Setting
1982 - Ronald Reagan declares his own intensification of the Drug War : This is met with widespread public approval. The USA DEFEND Act (To Defund, Extradite, and Fulfill Enforcement against Narcotic Dealers) is passed, giving the US Federal Government broad powers to arrest, monitor and seize assets. It also authorizes harsh mandatory minimum sentences for low and high level drug offenses.
1986 - Harsh drug policies that do little to curb the demand for drugs cause prison populations to skyrocket. Gangs are quickly gaining money and influence as addicts are forced to choose between prison and addiction. In California, the Bloods and Crips declare a truce to divide the territory of the LA metro area. The Aryan Brotherhood takes a foothold in the deep south. The Northeast a hotbed of competition between the Chinese triads and Italian mafia.
1995 - Incarceration rates are at an all time high. National Guardsmen in the streets of major cities are a common sight, and most police departments now receive surplus hardware from the US military. Texas and California are the first states to experience prison overcrowding, stretching their budgets. Bill Clinton coordinates with the Mexican government to allow the US military and federal law enforcement to conduct operations in Mexico. The dot com boom allows the US to enhance its pervasive surveillance program, but the well funded cartels are beginning to employ crytography to evade law enforcement. The new domain of the drug war is now on the digital front.
2000 - Frustrated with inter-gang violence and the inability of the government to restore order and combat the well equipped cartels, more and more citizens have decided to create militias and vigilante groups. Over 500 of these groups are active, using a variety of legal and illegal weapons acquired through gangs, black market dealers and corrupt government officials.
2006 - The loss in productivity from drug use, mass incarceration, a lack of normalcy and powerful organized crime groups has taken a toll on the US economy. The US inflation adjusted GDP is 9% lower than what it was in 1982. Corruption has become endemic. Several local cops and politicians are feeling the pinch, and are falling under the influence of powerful cartels and whoever has the money. The federal government manages to stay clean, for the most part.
## The Question
Fast forward to 2030. How would a criminal gang claim legitimacy in a city that has been under their control for about a year? Said city has transferred control several times in the last 10 years, from the city government, to the federal, and even a few militias. This city is home to 3.5 million people, has a lot of technical and political significance that could help the cartel with it's operations, and is a transit hub that leads to a large suburban population and the Gulf of Mexico.
[Answer]
Your question is really about what is called "Parallel structures" in Revolutionary Warfare Theory.
Essentially, the task of the revolutionary is to gain the support of the population and wean the population away from the existing government. Parallel structures are just what they sound like; police and security services, courts, health care and other services in contested and rebel controlled areas which provide the same or possibly "better" services than what the government provides.
If the government is inept, corrupt or simply lacks the resources to provide services in an area, then the people in the area might be inclined to support the rebels, simply because having the ability to have your property protected without having to pay off corrupt police, or getting justice in a dispute in a revolutionary court without worrying that the other side has pull or has paid off the judge will seem very attractive. Of course the Rebels will be demanding "taxes" or other forms of payment for the service, so the population (and the rebels themselves) need to balance the cost and effectiveness.
In the real world, the Muslim Brotherhoods in Egypt were a very small factor in Egyptian society and life until a devastating earthquake in the 1970's exposed the corrupt and inept nature of the government. Brotherhood offices in poor neighbourhoods distributed food and blankets to desperate people, gaining legitimacy in the eyes of the poor and building the platform to launch themselves to the point they managed to win the first election after the "Arab Spring". (They screwed up *being* a government, but that is a different discussion).
Drug lords in Mexico and South America do similar things, including setting up schools and hospitals with their profits, undermining the authority of the government and buying the loyalty of the people. Getting intelligence on what the narcos are doing is difficult when people look to *them* as the local authority, rather than the government.
On a cost effectiveness basis, this is much better than sending in thugs to terrorize people (like ISIS does). Terror works best in small, controlled doses against specific targets. Large scale terror can and does often bring a response from the people who are tired of being terrorized; The "Anabar Awakening" in Iraq, local village elders leading their young men against the Taliban in Afghanistan and Mexican villages driving out drug gangs are all examples of spontaneous action against the people terrorizing them (in the case of the "awakening", American commanders were very quick to get on board and use this to their advantage). How well local efforts work depends on many factors (including the resources available and the cultural background of the counter insurgency - non warrior cultures or people with limited resources may gain temporary relief but get smashed by returning rebels, drug lords etc.)
So it is quite possible and even probable for rebels, insurgents or drug lords to leverage their resources to create parallel structures and become the "legitimate" authority in their areas. Indeed, it is probably the best means they have to secure their gains and prevent the government forces from being able to easily eject them.
[Answer]
How have governments ever established legitimacy?
* Providing for their citizens' safety and well-being,
* Defending against external/existential threats,
* Working toward a monopoly on the use of force,
* Engaging with external governments on a peer-basis.
If your gang can do those things and sustain them, and the acceptance of the large majority of their population accrues to them, they'll be the legitimate government. This might be a matter of years, decades, or generations, depending a *lot* on external factors. (Are other cities/gangs doing the same thing? How's the US as a whole doing? &c.)
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Some well-documented historical examples would include (and I'm just shooting from the hip, here):
* Achaemenid Empire (in one generation goes from backwater, servile tribes to conquering/uniting the Lydians, Medes, and Babylonians)
* A bunch of backwater farmers and merchants throws the British out of its American colonies
* Ideologues and those tired of imperial rule tear down 200 year-old Imperial Russia, engage in two revolutions in one year, and five years later there's a Soviet Union.
Tipping points mean that change can happen fast, but calcification into the new state can take time....
[Answer]
**Could they just get legitimacy though elections?** They might even be able to get legitimate votes from normal citizens if they are providing the stability that other cities don't have.
Get one or more of their people elected to some public office.
Maybe get/bribe people in the local law enforcement to be on the payroll.
Start pushing their agenda, which is to have the freedom to operate without federal interference.
Get people inserted into some of the federal agencies to deflect or inform on investigations
Use the new political power to push out or subvert any political rivals.
Since they control a lot of the crime in the city, they should be able to make it stop or direct it, so crime rates go down, which makes people happy.
With all the dirty money they can invest in bringing in more legitimate businesses, which creates more jobs, which make people happy. It also helps launder the dirty money.
Keep the city in good repair, and people are happy.
There really isn't a way to just own the city without the threat of federal intervention, since it's still inside the borders of the US, but if they are able to whitewash everything and avoid getting to greedy which could draw attention, they could potentially operate without the feds stepping in and shutting everything down.
EDIT:
Reread the part about the city changing hands, including with several militias.
If "non-government" groups have had legitimate control over the city in the past, then this gang could do it the same way the others did. (which isn't really spelled out in the question, but I assume you've thought about).
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Okay, so the Napoleonic wars are raging. Many men are dying in Waterloo. It appeared as if the Duke of Wellington and his allied army would prevail, but Napoleon rallied his troops at the last possible minute. They held fast and the Duke suffered many casualties before retreating.
Obviously this didn't happen, but what if it had? I am specifically looking for what might have happened directly (within a year or two afterwards) after the battle had Napoleon won. For now please ignore any reasons that this would not have been possible for him.
Please base your answers off of the condition of France and the rest of the world at the time.
[Answer]
I would say that history would not have changed too much.
Napoleon had alienated most of Kings of Europe, either by becoming King despite his humble origins1 or by invading/breaking all of major nations of Europe2. Remember that at his fall, he was fighting against Russia, Prussia, Austria, England and Spain.
Additionally, after twenty years of war, France was depleted of military manpower. I read some comments stating that some of the French troops at Waterloo were so young and hastily sent to the front lines, that they barely knew how to load their weapons.
Had he won at Waterloo, after a year or two the coalition would have arrayed new armies and would have pushed Napoleon out of power again, even if only by sheer numbers.
The possible side effects could have been greatest Russian and Austrian influence (since their troops would have been needed again), and less British influence in Europe (which could result in Belgium not regaining its independence in 1830).
The Austrian and Russian advantage would have been quickly lost, since both had severe internal divisions and because they were not playing the games that eventually were decisive (Industrial Revolution and Colonialism).
1 Probably they did not want people in their own countries getting weird ideas.
2 Additionally, he promoted the Napoleonic code that, while absolutist, drew some ideas from the French Revolution (making him more dangerous to the *status quo* than the usual conqueror).
[Answer]
There was an Austrian Army of 250,000 men just a few days to a week's march off on the upper Rhine. There was also a 200,000 man Russian Army moving up towards the Rhine that participated in the pursuit of Napoleon after Waterloo.
So if Napoleon had won at Waterloo, odds are high that these Armies would have defeated his weakened force in a very short time.
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Over the course of Homo-sapiens, we have become larger, because of diet & selection. [Even in the last couple centuries](http://en.wikipedia.org/wiki/Human_height#History_of_human_height). Today, we vary across geography and cultures, too, of course.
Now it is thousands of years in the future (your call) and people live happily on Earth, but have evolved to be much smaller; still in proportion, just smaller even than our distant ancestors. We've grown in population, but have stabilized the Earth's issues and become highly sustainable: almost Utopia.
What contributing factors helped make us so much shorter over time - even those staying on an Earth?
[Answer]
Over that timescale and without a major crash in population (which could reasonably be recovered from later), the only real option is intelligent selection.
Important note: The change in average height over the last few centuries has nothing to do with evolution. Those genes for height already existed; the thing that changed was childhood nutrition. (Less important note: this gives an important hint about why height is usually considered attractive in humans, taller people in the ancestral environment had fitter parents, indicated by the fact that they were less malnourished than everyone else.)
Evolution is very slow; the number of generations required for a new gene to become fixed in a population is equal to $2 \frac{\ln(N)}{s},$ where $N$ is the size of the population and $s$ is the increase in fitness the mutation creates. For our population of 7,000,000,000, that means 45 generations even for a mutation that outright doubles the number of children you have. Clearly, small increases in fitness like "short people are sexier" (*Maybe* an increase in fitness of .01, most people can find mates even if they aren't that sexy. And it's probably much lower.) just aren't going to cut it even in several thousand years.
So how could it happen? Genetic screening! Or any other sort of technology that lets parents intelligently choose which of their genes to pass on to their offspring. If a whole bunch of people have access to the technology and are influenced by similar selection criteria they could easily massively increase the fitness of those genes which they want, making it very easy for those genes to become fixed in the population very quickly.
The main question you're left with is why they'd all have that same favor towards shortness. The first thing that comes to mind is some sort of tax break or subsidy put in place by governments for people who have shorter children. They have a smaller carbon footprint and you can fit more of them in your cities, seems pretty sensible to me.
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In evolutionary biology, a dwarf subspecies can be created by isolating a population on an island (or creating an island effect). Since resources are limited by accident or design, the trend is for the population to gradually become smaller as smaller individuals have a greater chance of surviving and reproducing than large individuals in the limited resource setting.
Dwarf mammoths existed near the end of the last ice age in isolated islands in the arctic after their large brethren were hunted to extinction. Homo floresiensis is an example of a hominid species isolated on an island which gradually shrank until the average individuals were about 1 metre tall. Even today, deer in some parks and military training areas are much smaller than average since they live in restricted "islands" of resources (deer who wander off are subject to hunting or death by automobile), and should this continue for another century or two, a new race of deer will exist.
Humans might naturally shrink in the far future if they are living in asteroids or small colonies in unpromising environments in space. The need to conserve resources so you can survive and reproduce will have the same long term effect as being isolated on an island. (This ignores the effects of genetic engineering or the ability of future humans to harness advanced technology to increase their access to resources and energy even in these environments).
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Many researchers have pointed out that our taller height is a product of over nutrition. Basically, we feed our children excessive protein and calories and these two elements promote growth in height, lean body weight and fat.
A report by The World Cancer Research Fund stated that we have grown taller, heavier and increased our chronic disease as a result of the industrial revolution and the associated Western diet.
Most children are overfed in terms of calories starting in infancy. A well-balanced diet with moderate protein and calories could reduce our size.
Birth weight is also a factor. Most studies have found that birth weight correlates with adult height, weight and body mass index. Birth weight is related to the mother's height, weight before pregnancy and weight gained during pregnancy. Thus, smaller mothers would produce smaller infants who wouldn't grow as large. Japanese women cut their calories when they get pregnant to avoid getting fat. As a result, their infants are lower in birth weight. This practice has been going on for many years and Japanese males have leveled off in height at about 5'7. This practice should be done under a doctor's supervision to assure adequate nourishment of the infant during pregnancy.
[Answer]
Howard Fast wrote a story "[The Vision of Milty Boil](https://books.google.com/books?id=b7ZHMRwFouYC&pg=PT20&lpg=PT20&dq=The+Vision+of+Milty+Boil&source=bl&ots=VSNGlUrK2U&sig=qlcY6i40pE2cnu_hSCYmJ5kygpU&hl=en&sa=X&ved=0CCYQ6AEwA2oVChMI2c28iNPexgIVE-2ACh11ZQU_#v=onepage&q=The%20Vision%20of%20Milty%20Boil&f=false)" where a developer started making cheap housing with shorter and shorter ceilings. He also started mass adverts promoting shortness, made movies feature tall, hulking villians and short, attractive heroes. Eventually everyone was less than 3 feet tall.
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Parents don't want their kids to die of cancer or diabetes. Nor do governments want to spend billions treating these conditions. [Laron dwarfism](https://en.wikipedia.org/wiki/Laron_syndrome) is a genetic condition that causes the growth hormone (GH) receptor to work less efficiently. The resulting insensitivity to growth hormone, or "GH resistance", confers [nigh immunity to cancer and type 2 diabetes](http://www.cracked.com/article_21013_5-groups-people-who-developed-awesome-mutant-superpowers_p2.html) and reduces the harmful effects of aging.
Based on other answers, I can think of a couple ways that the Laron allele might be selected for.
* Genetic screening for the Laron allele could become popular. Parents could arrange marriages to Laron dwarfs, or governments could provide tax breaks or health insurance subsidies to families with at least one Laron parent or two Laron carriers. In the limit, Gattaca-style recombinant "designer babies" would have the GH receptor gene corrupted on purpose to the Laron genotype.
* A more carcinogenic environment would cause a population crash, giving Laron dwarfs more chance to survive (make your time) and reproduce. So might the diabetes-prone high-calorie, high-carbohydrate Western diet.
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In [*2312* by Kim Stanley Robinson](http://www.eyrie.org/~eagle/reviews/books/0-316-19280-5.html), the engineered "littles" had small bodies and other significant features, all having to do with longevity. At the time of the story it was remarked that no "little" had ever died of natural causes.
These (or other options) were chosen by parents as developmental attributes for their children, so it did not require a genetic bottleneck or selective reproduction of parents with the desired traits.
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Suppose a world has huge underground caverns, capable of supporting large agricultural societies (something like described in [Our Hollow Earth](http://www.ourhollowearth.com/Bernard/Chapter7-2.htm)). What technological level, or better yet specific technologies, would the surface need to detect the underground dwellers? In the 20th century, geologists used nuclear tests to help map the inside of the earth; is that what's needed?
Let's assume that the cave people are not taking any extraordinary measures to hide, like magical acoustics to redirect the force of earthquakes and explosions and thereby hide from seismic mapping. However, they travel about the surface very rarely, so they're not going to just bump into the surface people. Bottom line: they topside people are not *looking* for underground civilization, but would investigate if they detected caverns totaling many cubic kilometers in volume.
Let's also assume that the troglodytes have no widespread industrial technology, so no massive release of CO2 or slag to dispose of... but if we can answer that too, bonus points!
[Answer]
Turn it into an answer
Shallow
* Humans are explorers and the unknown beckons us pretty readily...if there were surface entrances to these caverns, they probably would have been discovered relatively early in our history...either through dedicated explorers and spelunkers looking to venture where humanity hasn't before or attempting to get a cave network named after themselves (this would be more the exploration of a new continent or somewhere we haven't been before) or through curiosity, potentially even children, if these locations were nearby existing cities/towns/farms.
Deep
* Mining for various minerals has been around since recorded time. Depths vary of course, but we've been a long ways underground before AD.
* In the late 1800's, James White discovered the Calrsbad caverns. He saw a cave that was populated by an army of bats...any cave that can hold that many bats must be huge, and exploration began. Admittadely this is the white mans account, Native americans could have been down there far before we 'discovered' their land.
* Magnetic survey developed in the 1850's and was capable of detecting changes in magnetic fields underground. Caverns and caves could be detected as probabilities.
Deeper
* Passive Seismic surveys can see a good 250m below the surface pretty clearly and caverns above 1km are readily known. Passive is detecting the tremours that naturally occur. Average oil well is in the 3000ft deep range (1000 meters), and we are pretty adept at detecting those...by the late 1990's we had mapped the majority of oil producing lands to about 5000 feet.
* Hydrolic fracking operates at a depth of 5000 to 20000 feet (1000-5000 meters) and requires an active seismic reflection study..this is us causing the seismic ripples and watching what reflects them...We see layers of rock at this depth, and holes in those layers of rock are the oil pools we are looking for. Unsure if caverns is really feasible at this depth.
Deepest
* Russians have drilled to a depth of nearly 12km, Americans to about 10km (bertha rogers). Seismic reflection was able to detect pools at this depth, however Bertha rogers had to be abandoned after it struck molten sulphur around 9500 meters deep. We can see layers of the earth at this depth, but not much else.
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Seismic detectors would detect these cavern's interference with the detection of earthquakes' S and P waves without any new technology.
Once you have them located setting off small charges on the surface would do for more detailed sonar work.
[Answer]
Depending on how deep these caverns are, and the composition of the earth above them, detecting such caverns could be done in many ways, several in our current technological state and some with more archaic means.
## Near Surface
Let's assume they're only a few metres (10-15m, ~30-45ft) deep, and the earth above them is comprised of granite, or another solid stone. In such circumstances, caverns can be detected by our modern technology in the form of [ground-penetrating radar](http://en.wikipedia.org/wiki/Ground-penetrating_radar), often used for archaeology or other low-depth scanning. Said technology was recently used for [mapping the ground around Stonehenge](http://news.nationalgeographic.com/news/2014/09/140911-stonehenge-map-underground-monument-radar/), with surprising success. If modern humans were using this technology, they could stumble across underground caverns, and don't forget that humans are *curious* [citation needed], especially scientists. They might want to check out those caverns, leading to a great discovery.
## Let's Go Deeper
What if people were mining in a region? Mines can be [**deep**](http://en.wikipedia.org/wiki/TauTona_Mine), the deepest reaching multiple *kilometres* down. Humans have been mining for thousands of years, with ever-increasing scale and depth. Occasionally, a mine could be built that would intersect one of your caverns. Or what if a mine collapsed, or a cavern near a mine collapsed during blasting, revealing the cavern nearby? People will potentially find it and, being people, want to check it out.
Lately, we've also been doing an awful lot of drilling (for oil, natural gas, etc.). Maybe a drill-well could intersect a cavern and, if science was curious enough, they'd want to check out this massive cave network they found (probably during the initial surveying of the drill site).
And what about something as simple as a spelunker going down a new cave entrance that no one else had ever explored? Earth's caves are big, and some are interconnected in strange ways! New passages can open all the time as the ground shifts or erodes. Eventually, a hole may open somewhere and humans could find their way in. Spelunking is a modern hobby, as far as I can tell, but it has still been practiced for [decades](http://www.pelican.com/blog/2012/09/06/history-spelunking/). One does not need much tech to find an inhabited cavern completely by accident. Let's hope it doesn't turn out like it does in some of the movies, however.
There is also the possibility of deeper scanning, as noted [here](http://www.livescience.com/29794-earth-cat-scan-101104.html), which could easily spot a large cavern given time to refine the process.
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This alien spacecraft would be orbiting around earth at 300-400 km, it has a similar size to the ISS, and it has to be undetectable with our current technology. I assume that it would prevent emitting heat, maintain radio silence, absorb radio waves, and have to bend light around it to be invisible to passerby satellites and surface telescopes. could there be another way to detect it?
[Answer]
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> I assume that it would prevent emitting heat, maintain radio silence, absorb radio waves, and have to bend light around it to be invisible to passerby satellites and surface telescopes.
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Radio waves can be deflected to reduce the radar return - the technology is old news on Earth, too.
Light bending is unnecessary; at any reasonable distance, it wouldn't cause significant occultation of anything. It would need to keep track of the position of Earth and any manned vehicles, and never come between them and either the Sun or the Moon. Other satellites aren't really equipped to image other satellites.
So-called *transits* do exist and are seeked by amateurs and professionals alike, but they rely on accurately fixing and focusing a known point. If the ship doesn't follow a predictable orbit, at any reasonable zoom there will never be enough time to focus and detect it after the occulted star has blinked. Sun and Moon transits are far more dangerous, and to a lesser degree planets will be -- but the number of such large background objects is manageable.
In the case of Jupiter, its angular size is approx between 30" and 50". An ISS-sized object in ISS orbit is about a third of that, so at best 20". Now our ship is in a ~90' orbit, that is to say it covers 360°, or 1296000", in 5400" - a speed of 240 arcseconds per second. A partial Jupiter occultation (otherwise you'd just see Jupiter "blink") will then last about [a tenth of a second](https://www.youtube.com/watch?v=VBIDyDVyuQI) and you need a special setup to catch it reliably, and even there you know in advance when it's going to happen.
Meanwhile, the ship just needs to keep track of its "Jupiter" shadow (as well as the others), which is a 100-m wide track on the ground, and steer it over water or high-light-noise areas.
Another possibility to muddle detection would be to camouflage using [counter-illumination](https://en.wikipedia.org/wiki/Counter-illumination) (easier than light bending). 1945 technology, and pretty naive at that, proved able to decrease detection by a factor of six. This would also help against visible imagery being taken by remote sensing satellites in higher orbit.
The same tracking would detect "windows" in which an angle of more than 90° (but less than 170° to avoid a possible Gegenschein-like interference) exists between the ship and any (or, in emergencies, "most") potential infrared observers. Whenever that happens, accumulated waste heat can safely be radiated from the vehicle at that angle.
The big problem here, though, is **how to identify potential infrared observers**. Unless equipped with Culture Effectors or the like, your ship cannot be sure that any satellite in an higher orbit, up to geostationary, might not carry IR imagers. Yes, transmissions can be detected, decoded and compared with IR images, but *still*. And, once you catalogue all the various IR-imaging satellites continuously mapping the Earth (and do that before overloading your internal thermal sump), you might discover that they achieve a 200% coverage and you have *no* angles to radiate over.
Which would leave you with the awkward option of radiating at a tangential angle, to stay over the horizon for earthbound imagers and *hopefully* below the horizon of higher-orbit imagers (but at a height comparable to the ISS, this is bound to cause a detectable secondary heating in wide enough swaths of the upper atmosphere. The anomalies will be tiny, but they'll accumulate, and they'll look exactly like somebody was radiating heat in a stealth fashion; so it'll attract exactly the wrong sort of attention).
Another possibility is to employ a very inefficient "porcupine" radiator, with cylindrical emitters each directing heat in very narrow cones. In space, you have little atmospheric dispersion, so the waste heat ray *shouldn't* attract the attention of satellites out of line of sight.
Once the radar return footprint falls below that of a 15-cm aluminum sheet, one trivial way of reducing interception chances is *not to be on a fixed orbit*. Small debris is tracked using large radars (in Europe we have the FGAN Tracking and Imaging Radar or TIRA), and those radar use the knowledge of any given orbit's parameters to integrate and refine position over time. So, a return from point X1 in orbit family Y(1) followed by a return from point X2 in orbit family Y(2) will slowly coalesce into a solid acquisition of a physical object in the one well-defined orbit that best satisfies all detections. If there is no one orbit that satisfies a group of sightings, those will be ignored as spurious. Also, this so-called *target-directed* mode relies on *a priori* knowledge about the debris and how it came to be, so staying away from existing debris will further decrease the chances of being spotted.
Another, opposite trick once the existence of ground-based debris tracking stations has been deduced would be to *hide behind* one of the higher-orbit (thus, longer-lived) pieces of space debris. The radar return would mostly be that of the piece of debris, and its reflected luminosity would be enough to disturb even direct imaging.
This latter option could also be used to explain how suspicions on the ship's existence might come by: that particular piece of space debris, being large and in a safe orbit, would also be an ideal target for a junk-retrieval test mission.
Something like this happens, if memory serves, in Ted White's [*Secret of the Marauder Satellite*](https://www.amazon.it/ebook/dp/B079VVWT8T) (1967).
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**Distance** is all that's really needed.
A little bit of a frame challenge here, they don't need to be that close, and don't need any special shielding tech to go unnoticed if they're not.
We can't even spot inbound asteroids that might hit the planet until their really close unless we get extremely lucky, so just don't come in that close and they'll be very unlikely to be spotted .. and they don't need to be that close if it's a recon and observation mission so why do that.
If they've good telescopes (presumably if they're interstellar travellers they'll have pretty good ones) they can just sit out way beyond the orbit of Mars look at us through telescopes and eavesdrop on our broadcasts.
In addition to that all the stuff in the solar system orbits the sun on a single flat plane and as that's the only place there's anything interesting to look at that's where all our telescopes are pointed .. so they can increase their 'invisibility' by simply not being anywhere in that plane.
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Add a few simple precautions like engines off, radio silence, having the side of the ship facing us painted matt black and making sure any heat dissipation only happens on the other side of the ship (or better yet storing it and releasing it when their course passes on the other side of the sun to us) and for all practical purposes they'll be pretty invisible to us .. unless we're both actively looking for them (and unless we know they're there why would we) and get really lucky.
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Any active detection that rely on bouncing anything off them (not that anyone's going to be pinging them if they don't already know both that they're there and roughly where they are) can be deflected by the same methods already used in stealth bombers of course.
A good computer with 3D modelling of a decent star chart to ensure you don't accidentally eclipse any star or other distant object someone on earth just might be observing could also be useful.
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You won't be able to, short of ridiculously advanced super-science like access to other dimensions to dump waste and the like.
As always for Stealth in Space, the major problem is heat: you have to get rid of it, and delaying it by storing and then releasing only changes the problem because you end up being a lot thermally brighter when you eventually do have to dump it. And here is where your altitude really, really hurts. Putting aside whatever classified military birds looking down there might be and what their capabilities are, you've got systems like FIRMS, NASA's Fire Information for Resource Management System, which uses data from several satellites to track wildfires (and, these days, fires set by artillery to track combat in Ukraine) and is freely available. The data for that system comes from Aqua (orbit 703 km), Terra (709-is km), and NOAA-20 (820-ish km) Earth-observation satellites equipped with infrared detectors.
Then you've got Suomi NPP and the upcoming JPSS satellites, which carry the same sorts of sensors, the infrared camera on Landsat 9, and, making it worse for your aliens, the GOES-16, GOES-17, GOES-18, EWS-G1 (formerly GOES-15), Japanese Himarai series, the Russian Elektro-L series, the European Meteosat series, and Chinese Fengyung series geostationary weather satellites and equivalents which have the world (and any lower orbit) under constant 24 hour surveillance and also carry infrared sensors (albeit those on GOES-17 have problems).
Now, you can argue that the more distant birds have lower resolution and the ones in lower orbit narrower fields of view, and you'd be right, but there are more and more satellites going up there looking down, and the instruments that would detect heat emissions are relatively cheap and off-the-shelf, so more and more sensors.
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As a slightly different take on the problem: **You don't actually need to be undetectable**.
Here is a tip from Information Security point of view - instead of trying to make transfer of sensitive information undetectable, simple hide that needle in haystack of similarly looking information / noise. It is much easier and much more efficient.
So two easy options:
* be detected like something else (look like regular airplane with transmitting correct-looking codes, or like a weather balloon, or a other nation spysat, or Starlink satellite, or a drone, or a flock of birds, or whatever)
* actually look like flying saucer, and release to the human datasphere (i.e. the Internet) dozens of thousands of "real sightings of UFOs" over time (many of which are easily detected fakes, some are harder to detect but still provable fakes, and some which are unprovable but still likely fakes. Then just be one of the thousands of those unprovable but likely fakes).
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## If you are orbiting earth you likely already have the technology needed.
Getting to another planet using chemical or physically powered engines is incredibly hard, never cheap, and probably not economically sound. Anyone who is sending more than a basic probe is likely using an space folding propulsion system, or another physics based system.
Therefore light bending, heat radiating, and radar absorbing is simple. If you set you set your space folder to curve around you, you can act like you aren’t there, you can then put out instruments small enough not to be seen to see outside.
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This is not feasible: this object as described only absorbs energy and has some working device in it, without letting out any form of energy. Due to basic physics considerations it would end up exploding, as one cannot cram energy in a system forever.
It can be undetectable to some observation methods, but cannot be totally undetectable: it has to emitt enery somewhere, and that will make it detectable.
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In the real world it has been hypothesised that UFOS (Flying saucers) are surrounded by a bubble of high energy plasma that fulfils several functions.
One of these functions is said to be the ability to absorb or scatter incoming electromagnetic signals such as radar by deflecting it across its surface so that a radar beam that strikes the UFO from the front will pass across the surface of the plasma bubble and exit behind the UFO, rather than being reflected back at an angle that the radar station can pick up again.
This can be found in Unconventional Flying Objects by PR Hill,
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I've recently read some news about progress in building plasma reactors. The technology is basically that plasma is held by magnet field because otherwise, it would melt everything it touches. It has temperatures of millions of degrees celsius, i.e. hotter than the sun.
Now in sci-fi novels they often use fusion drives in order to move a spaceship. So if such an engine were to be constructed, it would probably again use some kind of a magnetic field in order to contain plasma.
What would however happen, if such a spacecraft were to be attacked? Let's say the engine hull is damaged (there is literally a big hole in it) and the magnet field is not working. It's vacuum out there. What would happen? Will there be a huge explosion? Would the plasma ball just be left behind (assuming the spaceship is still moving)? Would it melt the spaceship immediately?
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Well, a "Fusion Drive" as we understand it today would generally be a toroidal magnectially confined stream of plasma that is hot enough to undergo fusion. The destruction of one of these drives would likely be much less catastrophic than you would imagine.
[](https://i.stack.imgur.com/rdA79.png)
## Plasma Dispersion
At its core, a fusion reactor has superheated plasma that is millions of degrees Kelvin, and compressed by the powerful magnets around it. However, this likely wouldn't create as big of an explosion as say, a fuel powered engine of the same size. Why? Because in a traditional explosion of an engine (say when a plane crashes), what you're actually seeing burn is the fuel that was was stored to be used in the engine. For a fusion reactor, that fuel is potentially only a few kilograms of deuterium and tritium at most for a scaled up fusion reactor.
At a few million kelvin, the venting of the internal plasma would still be significant, something on the order of 10-100 lightning strikes going off at once. But this is nothing compared to the catastrophic explosion you'd get from a traditional fuel explosion that you'd need to power the same ship.
## Magnetic Explosion
The larger danger you'd face in space from a catastrophic fusion reactor failure is the magnetic explosion that will happen as the toroidal array of magnets comes out of alignment. I can't find any exact numbers on how fast the parts might accelerate away from each other, but the power behind the magnets on fusion engines are immense. Some designs even use the magnetic compression itself to heath the plasma to the required millions of Kelvin to begin the reaction. If any misalignment were to happen due to damage, the forces holding the plasma inside would rip the engine apart, sending the electromagnetic parts flying away from each other in every direction. In space, this kind of shrapnel would be far more deadly than some hot gas being vented.
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It depends, but depending on conditions it will either explode or simply evaporate - probably the latter.
Plasma can have temperatures of millions of degrees, but it is important to note that it isn't *hot* because it's *plasma*, rather it is *plasma* because it's *hot*. The magnetic field isn't just containing the plasma, it is compressing it as well, which is *why* it is hot. Take away the magnetic field and the plasma will rapidly expand and cool into gas; how much damage it does in the process depends on how tightly it was being compressed and how much of it there was.
That being said, it is worth noting that one of the main principles of modern engineering is that systems should "fail safe" whenever possible. For example, nuclear power plants are constructed in such a way that common malfunctions like power failures will cause the reactor to break, but not explode.
Of course there is only so much you could do to account for all contingencies, especially when violent attacks are involved, but any competently-designed fusion drive will probably be designed to account for the possibility of the magnetic field unexpectedly shutting down and not cause an explosion due to something so trivial.
The plasma would definitely not be left behind; it is moving at the same speed as the rest of the ship and will continue to move at the same speed unless acted on by an outside force.
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Fusion is by far the safest spaceship energy source with our current knowledge (yes, solar is safer as fusion happens far away, but you don't take the sun with you - if you do you have fusion drive again). It is safe mainly because it is such a pain to get the reaction going - so you won't have D+T fuse by themselves in a storage chamber.
(note - I took some liberties in conversion to have nice numbers, but most numbers are fairly close to the correct ones)
Inside the reactor where the fun stuff happens (well, will hopefully happen eventually), you have something like 10g of matter (1) at very high temperature and pressure that is producing energy. D-T fusion gives about 100GWh/kg, so energy content of that little ball of plasma is 1GWh, which is about 1T of TNT. Sounds like a huge explosion, but when the plasma hits magnets, it won't do much fusion - it will simply blast a nice hole in the walls and magnets before expanding and cooling to something non-problematic. Magnets will pop too, but for ITER 10kT of magnets are planned to have only 15MWh of magnetic energy in them - only 15kg of TNT.
That's it, nothing meaningful as far as an explosion goes. Deuterium and tritium (or whatever else the ship is using) won't undergo further fusion without magnets working (and if they did work, it wouldn't blow up in the first place). So the reaction stops as there is nothing to keep it going, D and T that were in storage scape through the new hole.
However, there is a potential problem - the ship might have a lot of oxygen stored somewhere for those humanoids (or other lifeforms). And it might have a lot of fuel to travel far. So, you are in some danger of D/T to make ordinary chemical reaction (= burning, or possibly explosion). If we take say 500T of fuel (2) and enough oxygen, this has potential to release as much energy as the first nuclear bombs, ruins a lot of oxygen and makes a swimming pool of heavy water.
(1): ITER will have 1g for few hundred MW. <https://www.nature.com/articles/s41567-020-1023-5>
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(2): This is comparable to oxygen+RP1 in Falcon 9. <https://en.wikipedia.org/wiki/Falcon_9#Pricing>
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The world has a kind of magic called chronomancy, essentially time manipulation. It can be done on two scales: local and universal.
Due to how the cost of magic works even the most experienced or skilled of human chronomancers have only ever been capable of stopping, accelerating, or reversing time on a universal scale for a few seconds at most before passing out from exhaustion, so for most chronomancers that's never even an option unless absolutely necessary and as such most time manipulation is mostly done on a local scale on a per-object (or living thing) basis. Chronomancers can slightly cheat the whole universal time manipulation thing by affecting themselves on a local scale, the universe from their perspective slowing down if they accelerate themselves and vice versa, though this carries the usual risks of them aging at an accelerated rate from everyone else's perspective if they abuse time acceleration on themselves throughout their lives.
I've already decided how frozen or time-reversed objects are affected by external forces, in that they are invulnerable or reversed in entropy/damage until they return to a normal or faster-than-frozen time passage, but I'm having a hard time deciding how a chronologically accelerated/slowed object (like an arrow in flight) will be affected by external forces or how it will affect chronologically normal objects when their slowed or accelerated forces interact with them.
**How would a chronologically accelerated/slowed object affect a chronologically normal object?**
*Things I have considered:*
* That a slowed down or frozen object would stay where it is relative to the universe instead of the gravitational object it was being affected by, causing all sorts of damage as the slowed down/frozen object goes the opposite direction of the planet's orbit it was affected by.
To resolve this I've made it so that the slower you go time-wise the more you are 'locked in' to your position relative to the rotation of your local source of gravitation, as if you're stuck in a Lagrange point if that makes any sense.
* That simply affecting an object won't do much and that you've need to slow or accelerate its entire path of travel for it to affect other things differently. Assume this is the case if simply accelerating or slowing the object won't alter any results.
[Answer]
## The Object's Mass Changes
Manipulating time, is basically the same thing as manipulating the Speed of Light. The Speed of light is a funny thing though because things that move at 1C have the same apparent speed in all frames of reference whereas things moving slower than 1C have apparent speeds based on their frame of reference. For time-space equations to balance, this means that when an object moves at relativistic speeds compared to another reference frame, everything in front of that object appears closer, and everything behind it appears farther away.
So, to speed up time, you increase the "constant of C" (which I suppose should be called the "variable of C" to a time mage). This makes the distance the arrow perceives equivalent to firing an arrow over a shorter distance. So, if you fire a 50 gram arrow at 60mps at a target 120m away, and raise C around the arrow to double its speed, it will traverse the distance faster as other people see it, but from its own perspective, it will just travel a shorter distance without gaining or losing energy. IE: the arrow only sees itself as only traveling 60m, but facing the same amount of air resistance as though it had traveled 120m.
So what about the impact? Is it more or less energetic? ... Assuming your spell is just trying to manipulate time and not pump more energy into the system, this means you need to change the mass of the arrow as it flies to balance your equation. So, if you accelerate an arrow with time manipulation, E=MC^2 could become E = (M/4) \* (2C)^2. So making local time move twice as fast would reduce your mass 4 fold. In this way, your arrow hits just as hard as it would moving slower, but gets to its target much faster. In short, your arrow effectively becomes a 12.5 gram projectile moving at 120mps.
*NOTE: it will hit with the same energy, but the [terminal ballistics](https://en.wikipedia.org/wiki/Terminal_ballistics) of the system will more closely resemble a bullet impact than an arrow. Low Mass, High Speed objects tend to pernitrate armor better than High Mass, Low Speed objects of equivalent energy.*
When you slow things down the opposite becomes true, the arrow moves much slower, but has a higher apparent mass.
This solution will also work very well with:
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Because a slowed down object is more massive than normal, it can still rest on the Earth and be manipulated sort of normally. You would think that this also means that it would sink into the Earth and become super heavy, but it does not because its reference frame becomes distorted to compensate. The object would fall much slower from our perspective and much farther from its perspective so the total energy interactions over time in each reference frame between the Earth and the object would remain the same. Inversely, If you are time slowed, everything around you would appear farther away and to be moving much faster but with the same total energy. So, if they bump into you, the energy transfer is the same... though their hand may still cut through you because of changes in terminal ballistics if they hit you hard enough.
Someone who is completely or near completely time frozen would become intangible. You would pass right through them like gamma rays. From their perspective, everything would become a very distant far away blur of light. Likewise, if you speed up an arrow fast enough, it will also pass through regular matter like a gamma ray as its mass approaches zero.
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A time-manipulated object has a magical aura that affects its surroundings, similar to e.g. a gravitational field: **it emanates its time-change**.
Let's say a slowed down arrow reaches a bird perched on a branch: as it gets closer, the bird will be caught in the arrow's aura, and slow down gradually. It might be able to perceive the arrow as a threat, and try to escape it, but as the arrow comes closer, the bird will increasingly slow down.
A chronomancer's ability/talent/skill might be decisive for the size of this aura, relative to the quality of the time manipulation (which is the sum of the duration and intensity with which time is changed).
If a time-altered item would be still relative to the universe, it would be extremely complicated to figure out (or perhaps even imagine) its impact on its surroundings.
Say a cannonball was frozen in time mid-flight. On the surface the earth rotates at around 1000 Mph. This cannonball will cause a lot of damage in very little time, no matter what, but how does the earth move relative to the cannonball? What is the cannonball's position relative to the 'center of the universe'? Will the cannonball actually move towards the chronomancer at that speed, and dive into the earth until it reaches its core at which point it might already be completely crumbled (I know too little about the resistance of metals to external forces to make an educated guess)?
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I would say they would interact with an impact of N, where N is the amount of time acceleration one item has. Or in the case of a deceleration, 1/N.
An arrow that moves twice as fast due to time has "trouble" interacting with its surroundings. After all, according to the arrow everything else moves aside twice as slowly, right? So the arrow will need to put in more energy to push the molecules aside fast enough to let it pass. From the air to the target it hits, it doesnt matter. Effectively according to the universe, the arrow simply has twice the energy until the spell fails and the normal time resumes on the arrow. The arrow will have lost more energy during its flight than normal and will go slower than expected because of this.
For an object moving slower the exact same is true. If you were firing an arrow 4x faster than normal and then made it go half speed, it would have the exact same impact as the previous arrow sped up. Only when time resumes it would have more energy left than before.
However you have to be smart about it: if you accelerate an arrow before firing it, it will take twice the energy to launch it at the speed of a normal arrow. The energy of the arrow hasnt changed just because you accelerated it!
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**Each object interacts according to its perspective on time.**
An arrow travelling at a target will be our example. The arrow has had slowing magic cast on it so it moves at .5 seconds for every 1 seconds of ours.
Arrow perspective: everything is now moving twice as fast. It travels the normal travel path and velocity to its destination but, the target has more resistance than expected and penetration is reduced as the target doesn't experience the full impact. The impact damage on the arrow is much higher for hitting the "harder" surface.
Target perspective: the arrow moves much slower and carries less potential energy. the impact registers much less. The arrow despite being slower travels in a normal travel path/arc.
Due to each perspective, the target is less harmed and the arrow is more harmed as it hit a target that experienced it moving slower.
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If time-stopped items are invulnerable, and time-reversed items are reversed in entropy, then time-slowed and time-accelerated items are the analogue: they are slowed or accelerated in entropy and internal physical processes. Time-acceleration or time-slowing an object doesn't inherently change how that object interacts with other things. Applying time modification to an area of space is how you get a "slow mo" or "fast forward" effect.
Let's look at some examples:
1. **An arrow in flight.** A lot of the other answers consider an arrow in flight. If you time-accelerate an arrow and then shoot it, I propose that the flight of that arrow would be almost entirely unaffected. The molecules of the arrow are moving faster. That doesn't affect it's flight or it's movement relative to anything else. It will cause the arrow to decompose faster, but that doesn't occur on a relevant timescale.
2. **A crossbow.** A time-accelerated crossbow will behave quite differently. Here, the enhanced crossbow will release it's spring energy substantially faster than a regular crossbow and therefore impart more acceleration on the crossbow bolt. Conversely, a time-slowed crossbow will shoot less hard. Be careful just to accelerate the crossbow itself and not the space around it.
3. **A person.** A time-accelerated person will be able to move faster because all of their biological processes causing muscle movements are accelerated.
4. **An area of space.** A time-slowed area will cause projectiles to fly slower through it, as the entire process of those things moving (air dispersal, gravity, etc.) are slowed. The same will be true of people entering it and leaving it. As soon as things exit the "slow" area, they go back to normal speed.
Now let's deal with physics problems. There are two doozies:
1. **How is energy conserved when objects move into a slow area?** This one is pretty easy from a high level perspective; the object has the same mass and velocity, but time is slower, so from the perspective of an outside observer, it will go slower. When it exits the area, it will be going faster again. From the perspective of an observer inside the area, everything outside the area is faster than natural and things move at their actual speed when they enter the area.
2. **Motion of molecules equals temperature.** If the molecules of an object are accelerated, won't that make the object hotter? Conversely if an object is time-stopped, does that mean that it's at absolute zero and will collapse? My best excuse for this is logic similar to that of objects entering or leaving time-modified areas. A time-accelerated object is just one that exists inside a time accelerated field that is precisely the size and shape of that object. So, while the object might read as very hot on a thermal camera or a remote thermometer, from it's own perspective, it remains it's normal temperature. If something comes in contact with it, that thing would be on the boundary of the time field and so would perceive that item as it's true temperature.
[Answer]
## Arrow off time, so it is invisible
Suppose your chronomancers could do this trick with arrows, or spears..
**Space time is 4d**
Time is the 4th dimension. A shift in time will make you disappear, even a shift in [Planck time](https://en.wikipedia.org/wiki/Planck_units) makes you disappear. You're lifted off from our 3d surface. To explain "off", suppose you'd be a flatlander: a flatlander shifted in time will exist somewhere slightly below, or above the universe plane of the flatlanders.
**No magic, no interaction**
Once you displace an object in time, your time-bow (or time-cannon) will never be precise enough to synchronize, or decelerate the projectile back into the timeline it left off from. Your target is in that timeline. Your arrow will miss *any target*, because the target will only exist in the unique timeline the arrow left off from. This is also the reason why time machines will never cause paradoxes involving your family or friends, because if you travel to the past, you'll affect the time line you'll arrive in, not your own time line. Only trouble is, when you travel in time, you'll never get back home.
Unless.. there is..
**Magic**
Yes, magic is needed. The chronomancers should take care of time accelleration and decelleration in such a way, that the arrow returns into precisely the same timeline where the target exists. It could reach the target 800x as fast, you would e.g. see your arrow kill a person instantly. For a person being hit by the arrow, it will not go slower or faster, it only arrives unnoticed.
Suppose you do this with a spear. A victim could see a spear coming in and try to dive away.. but a spear thrown by a chronomancer will always be invisible, it will just suddenly be punching your stomach. You did not see it coming in, because the spear was not in your timeline when it was underway.
**Impuls will remain the same: for an arrow, don't take your time shift too long**
Any shift in time, e.g. a second will do, to make the arrow disappear. But chronomancers found larger shifts have a disadvantage: they will slow down the arrow. The arrow will keep its impuls in space time. A time deviation too large will reduce the impuls left over for 3d space. Some laws of nature even chronomancers must take into account.
**Freeze the target with a sub-nano-second time shift**
A speculative & magic idea: there could be some minimal time shift that renders an object *really* invisible and non-interacting. Some delta (far) above Planck time. If you go below that minimal delta time, you'll see effects. The arrow will become vaguely visible, maybe there would be ice crystals forming, or ionization. In the atomic and molecular ranges, there's a lot of interaction between particles. When a time shift is a certain amount, it could affect e.g. the Brownian motion in gases and fluids. It could reverse impuls, or *stop* particles that exist in both timelines. The effect would be a freezing cold.
**The chronomancer's arrow can penetrate armor**
The arrow *will not be there* while it is moving toward the target.
Second speculation: a chronomancer could use a very quick deceleration, to let the arrow kill a knight in steel armor. It will move through armor indisturbed, while still off time. When the deceleration is accurate, the arrow could penetrate any shield and 'materialize' inside the knights's body.
[Answer]
**Depends 100% on what is Facilitating this chronological alteration**
As mentioned by another, a possible facilitation of this is a sort of "time-envelope" that envelopes the object within a set amount of space for a set amount of time (I'm assuming the effects are temporary) set by the caster.
* Objects within envelope experience time to be the same relative to each other.
* The surface of the envelope is the boundary of chronological field, may be a sharp boundary (perhaps even visible as it would affect light passing through as though slightly refractive) or a more fuzzy boundary where there's a bit of transition between time speeds.
* What happens though if half an object is in this field and the other half is outside? Or does the whole object have to be contained to work? Can I age just my scalp faster than the rest of me to grow hair quickly, fingertips for nails?
* Objects close to the effected object would be slightly affected the closer they came to the object until entering the envelope and being brought up/down to speed. The collision itself wouldn't seem to be impacted by the change in time flow itself, simply occurring sooner/later than normal. (unless part of the collision is to create a new time-envelope on what ever was hit)
Object specific time alteration, where it is not the space taken up by the object, but the object itself that is altered on the time line.
* The matter of the object itself is targeted and the interaction of time with that specific matter are effected.
* Effective changes to time would be visible through other observable phenomenon. Doubling in velocity, squaring of effective mass/inertia, a slight squeezing/stretching of the object to external observations, to whatever ratio matching the change in time speed.
* A one off effect, rather than a persistent field. (Increase/decrease existing qualities to compensate which then becomes its new "normal time" qualities)
* Affect on non-altered objects would be the same as if affected by a normal object with the new qualities (Hits twice/half as hard etc)
Magic - (You basically just write the rules)
Time is a magical force that can be manipulated much like heat, light, and physical work.
* Magic can place the affected in a demi-plane bubble with different properties than the normal universe.
* A magical force pushes or pulls against the stream of time like a paddle, pushing your time bubble further up or down stream.
* A time bubble, when colliding with an object of normal time may POP, causing chrono-side effects (potentially wanted effects in the case of arrows etc) or the bubble may remain in tact and cause the object to "bounce" off. Such a bounce may inadvertently Push the normal-time object forward in time slightly. Pushed hard enough, you might send something or someone into next week!
But again, it just depends on how the whole time altering even works. With more details, I'm sure I can give better options.
General Sanity comments:
* A fraction of a second's worth of "absolute position" in a constantly moving universe would be detrimental to any to discover it, instantly slamming you into the earth, space, or nearby structures.
* Gravity is not apart from Time, as gravity is shown to affect the passage of time, so an object frozen in time would not likely suspend itself midair as the non-time stopped earth would still have it's full pull on it (or the envelope of time containing it).
* There's all sorts of fun to be had with the boundary of a time bubble. Imagine a troop of archers lined up for a volley. A bubble is placed around them to make them fast compared to outside. Suddenly that single volley becomes a carpet of every arrow in their quivers as each shot slows at the boundary while they load and shoot the next volley.
* For interactions between time affected and non-effected objects, I would generally treat the acceleration of time as a multiplication of energy, and a slowing of time a division of energy, until time became normalized relative to the two again.
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I have a person with a superpower to interact with the world as though they were extremely heavy. The power is smart and selective, which allows him to walk normally without crushing the ground, or other undesirable effects.
I want him to be able to casually (at a normal walking speed, let's say 5km/h, without being significantly slowed) walk through a brick wall (or a similar wall that would be used as an external wall of a large residential building), but I'm not sure how much weight would be required to do so, and what the effects would be for his other interactions (eg. when punching stuff).
I can calculate his momentum/force, but I have no idea how much force would be required to break through a brick wall, or where to find that information.
I have found questions about punching through a wall, but they focus on superstrong (or more precisely superfast) punches by someone with normal weight.
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To do a casual back-of-the-envelope estimate of going through a wall based on momentum at 5 kph:
* Table 6 of <https://www.sciencedirect.com/science/article/pii/S1018363921000155> estimates the horizontal shear strength of a cinder block wall at 0.43 megapascals (approximately 4.4 kg per square centimeter).
* A table found on a body surface area estimator page (by Jove, the Internet really does have everything, doesn't it?) at <https://www.calculator.net/body-surface-area-calculator.html?csex=m&bodyweight=155&bodyweightunit=pound&bodyheightfeet=5&bodyheightinch=9&bodyheight=&x=63&y=12> suggests that the surface area of an average adult male is 1.9 m^2. A coarse guesstimate of the frontal contact area is about 40% of the total so that yields 0.76 m^2
* Total force required is the product of the required pressure and the contact area, giving us 326,800 newtons of force.
* Force is mass times acceleration, only in this case, the person is decelerating as they contact the wall. We choose a (rather arbitrary) 0.1 seconds to decelerate when they contact the wall at the stated 5 kph velocity, justified only by the assumption that the human body is a bit squishy, giving us a ~13.9 m/s^2 deceleration. Plugging that into the force formula gives us an estimated minimum of slightly over 235 metric tons of mass required.
I'd probably multiply that by 2 or more, both to paper over any inaccuracies in the estimate and to make the action seem effortless, as the question asks.
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I don't know how much extra weight is the minimum that your character's superpower will have to simulate to enable them to break through a brick wall at a normal walking pace.
But I can suggest that a simulated weight in the weight range of elephants should be sufficient to break through a quite strong wall, even if not necessarily to walk through the wall.
I once found a century or so old article reprinted on the internet where a circus man wrote about elephants. He mentioned a fight between two bull elephants in the elephant barn of the circus's winter quarters. They fought until one elephant's tusk broke off and the other one pushed him through the brick wall, 14 inches thick, of the elephant barn. Despite the vast amounts of blood they shed, both elephants had only minor injuries except for the broken tusk.
And in another article I read about a contemporary villager in India who was injured by a flying brick when a hungry elephant broke a hole in the wall of his house and reached in to grab a bag of rice.
And in another century old article I read about a circus parade in an American town where the elephants were stampeded by a barking dog and ran through the front wall of a wooden house, through the house, and out through the back wall.
So I looked up more such stories just now.
Here is a link to a video of elephants passing through a gap in a concrete wall.
<https://www.youtube.com/watch?v=yUf2KltOc7s>
Here is a link to a video of elephants destroying a wall:
<https://www.dailymail.co.uk/news/article-4628602/Panicked-elephants-break-boundary-wall.html>
<https://www.theguardian.com/world/2021/jun/21/elephant-in-the-room-visitor-crashes-through-kitchen-wall-in-thailand>
<https://www.naturalhistorymag.com/picks-from-the-past/081596/the-elephant-in-captivity?page=3>
p. 73 here:
[https://books.google.com/books?id=Yk09AwAAQBAJ&pg=PA73&lpg=PA73&dq=elephant+pushes+elephant+through+brick+wall&source=bl&ots=ssIPiyqSjQ&sig=ACfU3U3DpRyj12BusHP5lYyMtNk6ERFxmA&hl=en&sa=X&ved=2ahUKEwj5vb-3wKP0AhXcSTABHQXlB6kQ6AF6BAgbEAM#v=onepage&q=elephant%20pushes%20elephant%20through%20brick%20wall&f=false](https://books.google.com/books?id=Yk09AwAAQBAJ&pg=PA73&lpg=PA73&dq=elephant%20pushes%20elephant%20through%20brick%20wall&source=bl&ots=ssIPiyqSjQ&sig=ACfU3U3DpRyj12BusHP5lYyMtNk6ERFxmA&hl=en&sa=X&ved=2ahUKEwj5vb-3wKP0AhXcSTABHQXlB6kQ6AF6BAgbEAM#v=onepage&q=elephant%20pushes%20elephant%20through%20brick%20wall&f=false)
[https://books.google.com/books?id=f4PzAAAAMAAJ&pg=PA412&lpg=PA412&dq=elephant+pushes+elephant+through+brick+wall&source=bl&ots=LPDDgAYGK8&sig=ACfU3U0hx6gt1\_YAeR4SQ67XCRheehhN8Q&hl=en&sa=X&ved=2ahUKEwjf3OqexqP0AhUgSTABHT9-CGkQ6AF6BAgbEAM#v=onepage&q=elephant%20pushes%20elephant%20through%20brick%20wall&f=false](https://books.google.com/books?id=f4PzAAAAMAAJ&pg=PA412&lpg=PA412&dq=elephant%20pushes%20elephant%20through%20brick%20wall&source=bl&ots=LPDDgAYGK8&sig=ACfU3U0hx6gt1_YAeR4SQ67XCRheehhN8Q&hl=en&sa=X&ved=2ahUKEwjf3OqexqP0AhUgSTABHT9-CGkQ6AF6BAgbEAM#v=onepage&q=elephant%20pushes%20elephant%20through%20brick%20wall&f=false)
<https://www.asesg.org/PDFfiles/2021/53-47-Sahu.pdf>
<https://news.mongabay.com/2021/07/sri-lanka-seeks-peace-with-pachyderms-as-human-elephant-conflicts-escalate/>
And if you don't think that mere elephants are heavy enough to simply walk through strong walls at a normal pace, just give your character simulated weight that is twice a much as an elephant, or 5 times as much, or 10 times as much, whatever seems to be sufficient.
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Unless your character is supernaturally durable there is no weight that will allow them to walk through a brick wall and survive. Brick walls are very sturdy. If you don't believe me find a brick and try giving it a solid thwack. Notice how that hurts. Notice how the brick doesn't seem to care. A well built brick wall will require many burly construction workers swinging sledgehammers with all their might to bring it down over the course of an afternoon. A human hit square in the chest with a sledgehammer will need to go to to the hospital for broken ribs or worse.
To look at it another way even when protected by a modern car, with seatbelts, airbags and engineered crumple zones if you crash into a wall you will be having a very bad day. Now imagine crashing into the same wall without all that added protection.
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**Closed**. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers.
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**Want to improve this question?** Update the question so it can be answered with facts and citations by [editing this post](/posts/185552/edit).
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Space explorers with same tech level as in alien franchise found a planet. Planet had some carbon based, earth-like flora and fauna on it, but it still needed some additional touches, not a full blown terraforming.
After ~100 years process successfuly ended, automated terraforming stations and bases stopped. Terraforming changed the planet ecosystem drastically, many species died off but others adapted and took niches, life on this planet is way more genetically homogenous so they evolve very fast compared to earth life.
Crew woke up from cryo-sleep and is ready to land, orbital station departed for other mission indefinitely. They took off suits but found out that planet (maybe atmosphere, maybe fauna, your call) is lethal (immediately or not, your call again) for everyone roughly over 25 terran years old.
Why ?
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**The oldsters had all been vaccinated. The youngsters not.**
In the real world, I got the smallpox vaccine when I was a kid. My younger brother did not. They stopped giving it to kids in the US between the years we were born.
In your world the old folks all got a vaccine that came out of use or was modified 25 yeas ago. Younger persons got a different version or were not vaccinated at all against that pathogen.
The immune response induced by this old vaccine combined with a germ on this planet combine to produce an overwhelming immune response, lung edema and circulatory collapse. If the vaccine in question were smallpox, I would die on this planet but my brother would not.
He might sneeze a lot though. He does that anyway.
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***Growth hormones & liver function:***
A native life form is partly compatible with humans and is parasitic in native species. In humans, growth hormones are suppressing these things, but only kind of. Thousands of parasitic cysts start implanting themselves in people from the day they arrive.
These produce toxins, especially when they hatch. Liver enzymes are high in children and teens, but as you transition to adulthood, the enzyme levels in the mid-twenties protecting people from hangovers when young begin dropping off. Simultaneously, the last vestiges of puberty begin drying up, which allows more and more of those cysts you've been acquiring all your life to hatch. Exposure to toxins does tend to increase the production of enzymes by the liver, so "natives" might have more enzymes, but also more cysts. Chronic exposure to these toxins could be causing premature cirrhosis and liver damage, so your citizens might be already seriously ill before they reach a crisis. Youth and good regeneration are just covering up and compensating for the symptoms.
Now your body is flooded with dying toxic parasites and you are poisoned while your immune system goes into overtime fighting parasites and you die from violent chills, fevers, aching, and uncontrolled diarrhea, all while shedding parasite eggs in great gobs.
* **PS** If the goal in this was to say terraforming was the cause of the mortality, then we can specify the parasite/s normal host, the neo-hare, Is globally distributed, but it's chief predator, the pseudo-fox, was wiped out. Now the neo-hare population has exploded, spreading what were rare parasites everywhere. A lot of treatments for parasites are often themselves toxic, so even if a treatment were available, it could cause liver damage itself, and killing parasites often causes them to release their toxins and triggers an immune response. Your people may be too infected to safely treat. People in space could visit the planet and get treated reasonably safely due to low levels of infection.
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# No, but you can create a similar effect
### Reduction in Lifespan
As cowlinator said, there aren't any natural phenomena that kill **every** person in a certain age group. You could argue that certain diseases might be able to do so, but it would be unreliable. However, we can vastly reduce the average lifespan of your colonists so that living past twenty-five is incredibly unlikely.
### Cause of Death
There are several directions you could take in reducing the average lifespan of a human, but one which I feel holds a lot of potentials is forcing every colonist to develop [pulmonary fibrosis](https://www.mesotheliomaweb.org/pulmonaryfibrosis.htm). This is not only consistently fatal unlike disease or natural disasters, but is currently incurable and probably still would be for your hypothetical colonists.
If the atmosphere of the planet was sufficiently saturated with a fibrous particulate, the development of progressively worse pulmonary fibrosis would be inevitable. You wouldn't be able to avoid exposure even with future-tech filters. [[1]](https://www.quora.com/Do-HEPA-air-filters-remove-asbestos-from-the-air) There are probably ways to industrially cleanse the air, but it's unlikely your colonists would have the necessary resources to do so.
### Explanation
The easiest explanation for the presence of these particles would be the byproduct of a biological process. More specifically, the byproduct of [aeroplankton](https://en.wikipedia.org/wiki/Aeroplankton). Without delving too deep into speculative biology, you could say an event similar to the [Great Oxidation Event](https://en.wikipedia.org/wiki/Great_Oxidation_Event) occurred after this specific aeroplankton was rendered hyper-viable by the tampering your colonists did to the biosphere.
I tried to find an example organic particulate to model yours after, but there weren't any low hanging fruit. So, just think things like silica, asbestos, and smoke.
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### Youth can sense danger better
Few variations on a theme here:
* A large cat like animal hunts in packs and uses high frequency sounds to synchronise their slow encirclment. The youth can hear it, feel uncomfortable, and slowly move away from the area, but adults cant hear it and can get eaten.
* A tree that puts out a high frequency sound, and asbestos like fibres. Youth can hear it and avoid the area, adults enjoy the peace and quite and shade, and then die of asbestosis.
* A mosquito borne plaque. Yellow fever. Ross river virus. Something like that. The mosquitos can be heard and slapped by the youth, but adults cant hear them.
Also it's not unheard of (at least here in Australia) to have animals that only attack a particular demographic. We had a pet gallah that would only attack adult males, my high school had magpies that would swoop and attack only teenage females.
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I am looking for a good reason to make radio communications on a planetary scale unfeasible or impossible. Short-range use is acceptable, but no transmissions should make it to orbit or over the horizon line. Hints on specific type and features of an atmospheres are welcome, as well as scenarios that involve no atmosphere.
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Edit concerning radio communications between to and from the planet, as dealt with in a different question: the important part would be that no transmissions would be able to leave the planet and reach orbit.
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Edit concerning technologies involved generating "radio" transmissions: i am most interested in the conditions that would make atmospheric or above-surface transmission of radio signals impossible/not worth the effort. i am fine with the idea of using crust-resonance, lasers etc for communications.
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To keep the signals from reaching space you would need a charged upper atmosphere that is strong enough to block most signals. This may result in some aurora borealis if my understanding is correct, but it's pretty set dressing at least.
The problem is that radio waves can travel through the ground too, so if you want to limit your communications range you need to alter the planets surface composition. Ever hear of [Aokigahara?](https://en.wikipedia.org/wiki/Aokigahara) It's the place where Logan Paul screwed over his whole career. Well that place blocks cell signals because of the hill's rich iron composition. Make your planet rich in iron and that will fix most of your problems.
However, the signal might still bounce between the ground and atmosphere and the high charge might cause nothing but radio static everywhere, so some hand waving or contrivium may be in order.
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First, before people start yelling "solar storms!" just bear in mind that even the craziest geomagnetic phenomena might not be effective against lower frequencies traveling long distances.
How this question is best answered depends on the forms of communication we're talking about. If you limit your technology to specific forms of communication (i.e., what frequencies we're dealing with), the constraints are easier to define, and it's easier to give you more specifics. (Microwave frequencies behave differently than FM, etc.)
As your question implies, you are already aware that some forms of radio waves will reach distances beyond the line-of-sight of the transmitter because of how they "bounce" off the ionosphere. But they can also travel long distances as ground waves. [This Wikipedia article](https://en.m.wikipedia.org/wiki/Radio_propagation#Ionospheric_modes_(skywave)) has some good info. So, it may be best to think of this question in two parts:
First:
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> No transmissions should make it to orbit...
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Generally speaking, in theory, I suppose if you had a ridiculously ionized layer of atmosphere, it could conceivably block most if not all signals from reaching *orbit,* so that solves half of your problem. (The science is a bit less simple than I'm making it sound, but that's the basic idea.) But again, the frequencies involved will affect this.
Additionally, the composition of the atmosphere itself can affect signal propagation. Altering the content of the various atmospheric gases could give you the effects you're looking for; different gases react differently to EM. Of course, too much alteration and the air will become unbreathable, or air pressure will become too high, and people will need EV suits. I recommend visiting the Physics or Space Exploration Stack Exchange sites for more info in these regards.
Second:
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> ...or over the horizon line.
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I would consider using terrain as a way to limit your range. Bodies of water and rugged, mountainous landscapes absorb a lot of EM radiation. Volcanic activity producing high amounts of ash *can* help, but anything short of a cataclysmic eruption would probably not cause much interference for long, and certainly not over a wide area. So, probably too unreliable for you to count on.
Note also that some weather can actually work against you and improve the signal range.
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> What would make radio transmission unfeasible on a planet?
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[**Fierce Geomagnetic Storms.**](https://en.wikipedia.org/wiki/Geomagnetic_storm)
A non lower-atmospheric solution is a very active sun that releases more or less continuous flares which beat on the upper atmosphere - as they do on Earth in an eleven year cycle - but if the ones squirting out from your star are more or less continuous, then they'd fit the bill.
* There's the storm of [March 9, 1989](https://en.wikipedia.org/wiki/March_1989_geomagnetic_storm) which disrupted radio stations - some believed it had been done by the Russians and was the start of something more sinister (it was during the cold war).
[](https://i.stack.imgur.com/pnzyR.jpg)
Creative Commons Attribution-ShareAlike License: Wikipedia 2018.
* There's a nice chart on [Wikipedia](https://en.wikipedia.org/wiki/Solar_flare#Classification) about their classifications and how big they get on Earth (a bit like earthquake classifications).
* There's a brief bit about potential [effects on animals](https://en.wikipedia.org/wiki/Geomagnetic_storm#Effect_on_animals) when it gets realy bad which may be worth noting.
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A mars sized planet would be more difficult for radio because of the enhanced curvature of the surface. A planet with an atmosphere thick with metallic dust also bad.. especially if that meant frequent electrical storms. A planet with a weak magnetic field.. allowing solar particles to penetrate the atmosphere.. basically mars.. with a slightly thicker atmosphere.
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This may be considered cheating, but... **Make the atmosphere highly noxious.**
We take it for granted that our planet has a nice atmosphere and significant protections from solar UV radiation. If the ozone never formed, UV would still be so intense that we would still be stuck in the oceans. Once you're deep enough underwater, the distance radio transmissions can travel is significantly reduced (more so for some frequencies in the low GHz range than others). Long-range transmission would thus be made infeasible not because the signals would be blocked, but because building transmitters in such an environment would be dangerous. The same thing can be done without resorting to an underwater civilization. Imagine a species like ourselves that live on Venus. We would need to live in underground and actively cooled tunnels to avoid the lethal combinations of pressure, acidity, and heat that plague the surface. Transmitters would not survive for much longer either.
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Is it possible for a sun-like star to hold on to about 16 planets? If so, where could the habitable zone be located at?
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**TL;DR:** Yes, you can have those, if you are willing to use a loose definition of "planet". Or you can keep it under/around 10 and meet the [IAU expectations](https://www.iau.org/static/archives/releases/doc/iau0603.doc) (hard science). As for the habitable zone, depends on your chosen star type.
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**Long version:**
We know very few about planetary formation. What we know so far is that it is [very hard](https://www.space.com/24894-exoplanets-habitable-zone-red-dwarfs.html) for a star not to have planets (a radical change from the [XX century](https://www.youtube.com/watch?v=MlikCebQSlY)).
But it is very hard to actually pinpoint the number of planets in a system.
The system with the most planets we know so far is [HD1080](https://en.wikipedia.org/wiki/HD_10180) that has between seven and nine planets. We know that [Sol](https://en.wikipedia.org/wiki/Sun#Planetary_system) has eight planets and a ton of planetoids (sedna, pluto, etc) so that is a good ballpoint number for *"hey that's a lot of planets"*.
Maybe we [could have one more planet between Mars and Jupiter](https://worldbuilding.stackexchange.com/questions/4093/if-there-was-a-planet-where-the-asteroid-belt-is-could-it-have-a-stable-orbit) if all the mass in the asteroid belt would congeal into a single body. Maybe one more if Pluto gathered the mass of the Kuiper belt. But this is speculation. More on [planetary mass](https://en.wikipedia.org/wiki/Planetary_mass)
Sixteen may be too much. Who knows. You could get away with that, but the star would have to be way bigger than the sun. Because of Kepler's third law, the orbits of the planets [(calculate here)](http://www.calctool.org/CALC/phys/astronomy/planet_orbit) would be influenced by the star, and further planets would need a bigger gravitational pull to remain in orbit. And there are tons of problems with multi-orbit like [resonance](https://en.wikipedia.org/wiki/Orbital_resonance)
The [habitable zone](https://depts.washington.edu/naivpl/sites/default/files/hz.shtml) depends on the star type. Here is a [calculator.](https://depts.washington.edu/naivpl/content/hz-calculator).
As a P.S: don't throw [dwarf planets](https://en.wikipedia.org/wiki/Dwarf_planet) in the mix (sorry Pluto) or you will get over 100 just in our solar system. (thanks Phiteros for pointing that out). Or do throw those in, just to meet your quota.
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On 16 planets, yes it is possible, if Jupiter were smaller and didn't interfere with the asteroid belt you'd likely have another planet in that orbit. Though not easy it is possible that 7 more planets could be captured in the kuiper belt and clear their regions, but most would likely need to be captured from outside our solar system which would be a challenge. One or two yes, seven would not be common.
On the habitable zone, if your system were like our solar system then it can be argued we only have Earth as a habitable planet. But I'd argue if Mars were only a little bigger and had a substantive magnetic field it would be habitable too. Now if you really want to maximize the number of habitable planets you have to get creative. So instead of Earth we replace it with a heavy Jupiter, with 4 large moons in its orbit, all now within the habitable zone. Next replace Saturn or Uranus with a red dwarf star, essentially creating a binary star system which is actually quite common. Then the red dwarf can have at least one habitable planet in its orbit, again if you are creative you might squeeze two by having a super Earth with a super moon ie both 2.5 times bigger than our Earth and moon.
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The habitable zone depends on the star, not on the planets.
Cleared this, in principle it is possible that more than 10 planets orbit a star. The "trick" is in preventing the formation of gas giants like Jupiter and Saturn which, with their mass, account for most of the mass of the system (central star excluded) and also whipe the surrounding from other bodies. Mass-wise you could split the mass of Jupiter in more Mercury-sized planets and easily boost the planet count for your system.
The problem is that, material-wise, rocky planets rely on metals for their formation, and metals are rare in the space, while there is plenty of gases to form gas giants and you cannot have earth sized gas planets.
Since our knowledge of planetary system is pretty limited and surely not yet statistically significative, we cannot rule out such possibility.
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Sixten? Only *sixteen*?
Theoretically, a star can have up to ***four hundred and sixteen*** platens in the habitable zone. See [here](http://nautil.us/blog/i-built-a-stable-planetary-system-with-416-planets-in-the-habitable-zone)
[](https://i.stack.imgur.com/sYul9.png)
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What's your time scale? A young star system early in its lifespan could have a few "extra" planets and proto-planets in meta-stable orbits. Relatively soon in geological timeframes, orbital resonances are going to stack up and pull things apart, but for the present everything is behaving itself. So the planets aren't going to crash into one another immediately, but I wouldn't set up shop there for more than a couple thousand years. And asteroid activity is still very high, so mind your flight vectors and keep particle shielding at full power at all times.
Of course, you're probably not going to see native lifeforms in a system like that, but some enterprising settlers might set up shop for research/economic purposes.
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After reading [this question](https://worldbuilding.stackexchange.com/questions/83543) by [Nick M](https://worldbuilding.stackexchange.com/users/39367/nick-m) (now closed) and exchanging some comments with him, I have some ideas related to the scenario. I realized that the comprehensive design covers several distinct topics and is not what the question asked, so I’m posting the questions I *did* answer, as new questions.
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**What would be a good economic framework to drive the motives of independent crews of [Kessler](https://en.wikipedia.org/wiki/Kessler_syndrome) Remediation and Salvage (KR&S) companies?**
The KR&S companies clear debris from Earth orbit. They compete for profit and eek out a margin.
But rather than being an efficient well-planned system that fairly divides effort and profit among all involved, it should resemble a system that emerges organically out of a long history of contracts and cut-throat deals, from participants who act selfishly for their own short-term gains.
This can be used as a background for a role-playing game, a strategy game, (or a combined role-playing strategy game!), or a story that has a complex plot in the manner of an action/political thriller.
Besides the KR&S crews, note what other roles are available for players. Players can both cooperate and compete with players in different roles and others in the same role. In general, it should provide for [maximum dramatic potential](https://www.youtube.com/watch?v=wES5ufXETdE) — or stated less dramatically, provide for conflict, differing motives among the players, and the ability to act on these conflicting motives independently of what other players are doing.
The tech level is near-future, with realistic things extrapolated from today’s designs. No 'magic' unobtainium!
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# After bidding for orbits at the auctions, the buyers want them cleaned
Today (most) [broadcasting](https://en.wikipedia.org/wiki/Broadcasting) markets in the world have been deregulated and are not subject to government monopoly. This along with a surge of private actors means that the [æther](https://en.wikipedia.org/wiki/Aether_(classical_element)) is quite simple too crowded to let anyone and everyone play in there at once. Hence [frequency space is auctioned out](https://en.wikipedia.org/wiki/Spectrum_auction) to keep some sort of order.
Now let us transfer this thinking to space...
[Private spaceflight](https://en.wikipedia.org/wiki/Private_spaceflight) is on the rise. At the same time governments are stepping back. The de facto monopoly is about to be broken.
Posit therefore that that which happened to frequency space, has happened to actual space. Orbits are after all a finite resource. And with too many actors around to allow everyone to fly willy-nilly at the same time, orbits are auctioned out.
So there you are: Your Corporation Inc. have just gotten themselves a nice and neat orbit to play in for their business purposes. Only problem is: the orbit is not all that nice and neat. To speak plainly, it is a right mess. After eighty-some-odd years of space flight, and after a boom period of private spaceflight — where more missions than the mind will comfortably conceive ended in disaster — the orbits are in fact quite polluted with hazardous junk.
Your Corporation Inc. wants their freshly purchased orbit made clean. But they do not have the necessary competence, nor the proper equipment, nor the experience to safely conduct orbit-cleaning operations. And since this is a pretty much one-time affair anyway, they do not want to have to invest in all that out of their tight budget.
Hence they turn to the new section in the Business-to-Business Yellow Pages...
[Answer]
Kessler Remediation and Salvage (KR&S) companies operate on *targets* which are derilict spacecraft (or pieces thereof) in Earth orbit. Every last bit down to dropped screws are to be removed from cluttering up space.
As planned (for the dramatic potential), this is a rather dysfunctional system that is, never the less, plausible in what grows out of individual actors all trying to act selfishly for short term gains — much like the real world.
Rather than coordinating the targets, or having crews bid on targets and file claims (which would be efficient and calm), **I have a “reverse auction” system** that sets up a [prisoner’s dilemma](https://en.wikipedia.org/wiki/Prisoner%27s_dilemma) situation between the companies, and also lets them “play dirty” on every detail.
The roles are: the Authority, the Responsible Parties, the Clearinghouses, and the KR&S companies.
Space junk is “owned” by some Responsible Party (RP). You can't tell who that is, even if the junk bears some logo or ID, because these are corporate “negative assets” that are bought and sold and traded and packaged as financial objects and so on. The RP is anonomous to the KR&S.
To manage orbital space, the Authory will impose taxes and fines. Out-of-the-way junk has a minimal tracking-tax, but stuff with orbital parameters that take it close to other bodies or extreme eccentricity etc. will have higher fees. As an effort to reduce the load of junk, there are incentives in the form of higher fees over time and fines for allowing the orbit to become problematic, or breaking into more parts, etc.
Here is the main economic model as the KR&S experiences it: The Clearinghouses [pun intended] are hired by the RPs. **The CH posts bounties on the junk.** The price for clearing a specific piece will start out small, and if there are no takers after some time, they will raise the price. Naturally if the junk is “cheap” to keep on the books they will offer only a minimal bounty, but if it gets older or moves into a dangerous area it will have a higher bounty.
And why it's cut-throat: The CH doesn’t care who takes care of it — it’s strictly pay on job completion to whoever shows up first. And they turn a blind eye to any dealbreaking and claim jumping among the KS&Rs.
Notice, for example, that if *nobody* takes a particular low-end target, the price will go up later. If one company doesn’t cooperate in waiting, it earns the current price. This is an example of the Prisoner’s Dilemma.
The logistics come into play, so targets on similar orbits are better to handle together, and different crews may currently be working different “lanes” so to speak. They can cooperate to divide up the work, … or not.
Meanwhile the Clearinghouses run logistical models on what the crews can do, and try to adjust bounties to provide opportunities for them that costs the least but allows the job to get done; or they can meddle with the dynamics between the KS&Rs by setting up conflicting motives. This indirectly provides a way for the CHs to affect other CHs, as they compete for profitable contracts with RPs.
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Every problem is also an opportunity. Getting resources into space is expensive. Mining asteroids is cheaper, but still not cheap since you have to get the resources from the asteroid belt, resources to the asteroid belt, and unlike what is depicted by Hollywood asteroids are actually very spread out, which means everything is really far away from everything else.
So while space junk is a danger, it is also a nearby resource which can be harvested and recycled.
Deorbiting junk is fairly simple, and I remember a proposal to pull junk out of orbit by using an electron gun to give items a charge, and then attracting or repulsing that to change the objects orbit.
Demand for resources would be pretty high once a couple fab units are put in orbit as a way to lower the cost of getting space craft into orbit by just building them there. These fab units would be able to process minerals from asteroids, but they would also be able to break down and recycled the processed minerals of space junk.
So KR&S companies would be started to electromagnetically lasso junk to be processed by the fab units to collect the salvage fees, and it's also possible that governments or companies might start a bounty program to encourage the capture of smaller objects that KR&S might not feel are worth the hassle of grabbing.
It is worth noting that NASA and the DoD cooperate and share responsibilities for characterizing the satellite (including orbital debris) environment. DoD's Space Surveillance Network tracks discrete objects as small as 2 inches (5 centimeters) in diameter in low Earth orbit and about 1 yard (1 meter) in geosynchronous orbit, and salvage companies would have access to this data.
This can be used as a way to provide extra bounties for high priority targets:
"There is a wrench on a collision course with this satellite, and will most likely destroy it. Let's put a $50,000 bonus on its capture so we don't lose our satellite!"
It can also be used as a double check to keep KR&S companies honest:
"We totally grabbed this bolt, which has a small item bonus. No of course we didn't break it off this other piece of salvage, who would do that?"
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I'm imagining fleets of salvage ships floating around out there...Zero-G garbagemen picking stuff up and saving it or flinging it out into the inky depths of space. I think Vince Gilligan could do great stuff with this.
Now that that bit of whimsy is out of the way, lets get down and dirty. Start With a Bureaucracy in Charge of Kessler Remediation and Salvage. The Bureau is responsible for mapping the skies into lanes and layers. Layers are a measure of how high in orbit something is and lanes are the orbital track the item is following. Various KR&S companies bid yearly on contracts to keep that part of the sky clean.
Different types of companies are going to bid for different lanes and layers based on their own capabilities. Company A wants to get a hold of recyclables and sell them to the ever growing ISS. The choice bits of debris may be lower in the orbit, so that's how they bid. Company C has pioneered a new ship that is really good at flinging small bits out deeper into space, so they may go for a higher layer. The only thing the Bureau cares about is clear skies. Whatever happens to the junk after, they just don't care.
Anything valuable that is struck in a particular lane and layer will subject the contractor responsible to stiff fines.
The Bureau pays very handsomely, and is also willing to help the various companies with regular ground based railgun resupply shots. The Bureau owns and and controls all planetside railgun operations. Given that getting mass into orbit for operations is usually the most expensive thing about space travel, A rail shot is a relatively cheap way to get stuff up there. A Railgun can get most everything but people into orbit, and can be powered by a couple of reactors nearby. People to man the ships go up in a shuttle and rendezvous with the stuff shot by the railgun and begin operations.
So there is the setup. Here's how it could play: Contracts are yearly. If a company wants to expand, they would have to take over another company's lane and layer (there is only so much sky, after all) that means under bidding or maybe other Shennanigans. Bribery of Bureau officials for cheaper rates on rail shots comes to mind. Maybe one company nudges extra debris into another area, hoping to damage something and trigger a fine on another company. Unions want higher wages based on time in Microgravity. The possibilities for gritty stuff are endless.
Ship types can be widely varied. One that wants to catch debris and recycle it is going to be tough and possibly expensive in terms of propulsion. One that flies higher may simply use arrays of electromagnets to sling anything magnetic into the sun. Anything that can't be handled like that, a spacewalking cowboy gets out there and attaches a small, disposable electromagnet to the object. Then fling it into the sun.
With corrupt agencies, cut throat companies bidding on contracts, Space unions, you have a great, widely varied background to play in.
Eventually, you might find Jimmy Hoffa's body, squished in an upper stage of an old Saturn rocket, where it's been floating for the last 150 years.
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The biggest issue in setting up this sort of system is the seed money and incentivisaton to actually go out there and do this.
I suspect that the startup funding and overall incentive will come from insurance companies, which will realize that paying for debris sweeps will allow their very expensive investments (satellites) to last longer and continue to produce profits, rather than becoming the cause of multi million to billion dollar payouts.
So orbital "cleaners" will spring up to collect payments from insurance companies to clear debris from the orbits of active satellites, but of course this will devolve into a sort of lowest common denominator thing, with players trying to get in low bids to get some money and contracts from the insurance companies, and the insurance companies carefully researching low cost technologies to allow this to happen. There is a "floor" of course, spaceships which are too flimsy or prone to breaking apart on their own will certainly not be favoured by insurance companies, since that simply compounds the problem.
The only real downside to this is the most effective technologies might not even involve going into space, a powerful ground mounted "laser broom" can be used to deorbit a great deal of space debris, with the only possible space based accessories being "fighting mirrors" in orbit to redirect the beam at targets in unusual orbits or fulfill specific contractual obligations (the debris must drop over a particular geographical area, for example).
While not quite as exciting as "cowboys in space", it seems much more realistic.
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My graphic novel involves a large flying city on a Venus-like planet. Yes, I have done my research, and for various reasons it will be an aerostat-hibrid megastructure: a metaphor for the elaborate and expensive man-made islands around Dubai – a status symbol of impractical engineering. **Please notice the question is not how but WHY.**
I am looking for worldbuilding reasons WHY this city was constructed, and the unique set of circumstances that make it viable. In other words, **what problem was solved by building a large luxury aerostat in a compromised atmosphere**, as opposed to a more common space harbor or moon-based colony?
Some background:
* The city is a corporate trade hub, and is a Libertarian paradise of luxury rentals and cheap domestic servants. The city has a Metropolis-esque division of wealthy families living on top of an unseen labor class.
* The star system is a choke point along a strategic trade route (FTL travel takes months, and involves "jumping" from star to adjacent star).
* The city has control over the star system, and they have politically destabilized surrounding systems (pirates, despots, etc). They support a syndicate-created scarcity of resources that doesn't touch them.
* There are no other habitable planets in the system. There is a profitable (exploitative) metal asteroid mining operation which was the original "oil money" of the city.
* **I am not interested in debating the feasibility of the structure, thank you.**
* My world is not hard sci-fi. Everyone is human. It's thousands of years in the future.
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I offer some loose reasons I think the structure might be better off flying in an atmosphere rather than in space:
* **Politics** – the city's location is politically advantageous avoiding taxes/criminal justice of an established government.
* **Astrophysics** – solar radiation or frequent meteor storms make an atmospheric canopy necessary.
* **Gravity** – Space is fine for the working class, but wealthy people refuse to live in bad gravity.
* **Defense** – The city is less vulnerable to attack with a planet at its back. Since they undermine other sovereignties, they have many enemies.
* **Security** – Removing the city from the space harbor creates physical distance from terrorists and rebels (and riff raff, [NOCD](http://www.urbandictionary.com/define.php?term=NOCD)).
I need to show that this structure is elaborate and expensive, but circumstances make it viable or necessary.
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## So you want Libertarian floating city on Venus like planet. Fair enough.
**You already pinned down why there should be a city of wealthy despots anywhere in the system**: asteroid mining and trading hub. I presume being libertarians, they impose heavy tariffs on use of "their" space for transit, and you either pay up, regularly fight through, get shot down or dragged into indentured servitude for violation of "non-aggression principle" (because you clearly violated it first by trespassing).
Remaining question is, why would it be an anti-intellectual version of [Laputa](https://en.wikipedia.org/wiki/Laputa) (technically libertarians don't claim to be anti-intellectual, but since they take Austrian "School" of "Economy" and "Praxeology" as core concepts, they actually are)?
**This is actually a hard question. A lot depends on history of the system.**
## Asteroid mining
**If initial wealth comes from asteroid mining, and current crop of governing despots comes from most successful miners, ore traders or industrialists who set up local ore refineries, then you should expect main "city" to be inside hollowed out asteroid, for simple practicality.** *Rothbard city* started out as hollowed city in asteroid, and since everything they needed to control their economic empires already was in place - as they spent less time actually working and more just managing others, their homes kept expanding and it was simply more expedient to add infrastructure and connect other asteroids. Heck, most likely every magnate would have own asteroid-city, where oxygen is expensive and even God is second after him. Or her. **No. That won't do.**
## Interstellar Trade
**What about FTL? How does it work? What is used for fuel?** You said it works inter-system by jumps which take months. Is it possible that for some reason all viable entry and exit points lie near *Ludwig von Mises*, the Venus-type planet? **Perhaps your FTL jumps need gravitational wells as anchors, which means that ships have to jump from and to planets?** Star is right out, because [radiated energy](https://en.wikipedia.org/wiki/Black-body_radiation) would destroy the ships. So now we just need to rule out other planets.
Alternatively you can make it so inexplicably there are no other jump points and skip the rest of this paragraph, your call, heck, it would make for an interesting story if it's not known why jump points are the way there are, and suddenly they reshuffle, or someone discovers way to "bore" new ones, or perhaps *Hayek system* oligarchy aggressively chases off any explorers to make sure no other entry points are discovered.
Back on track, **how about fuel? Are your ships powered by fusion reactors? Preferably ones which can operate on wide range of light elements?** That would be perfect, as planet with thick gaseous atmosphere provides ready source of fuel. **Normally, smaller ships could utilise scaled down [ramscoops](https://en.wikipedia.org/wiki/Bussard_ramjet) to skim very outer layers of atmospheres to refuel, larger ones could carry shuttles to do the same** (actually landing on atmosphere-less planet to mine the surface is hard, landing on planet with atmosphere is easier, but take-off is harder, just skimming the outermost layer beats both by huge margin).
**Obviously, "government" of *von Mises* considers that theft, either you buy fuel from them or something unpleasant happens**. If other planets lack atmosphere, denying refuelling would require a few automated battle stations to fire on anyone who lands. After they land, why bother shooting them in flight? If they somehow survive destruction of ship you can offer to *rescue* them. At a price. After they pay fine for trespassing. And compensate you for spent ammo. And pay for [depreciation](https://en.wikipedia.org/wiki/Depreciation) of value of battle-station which shot them. And... well, you get they idea. It's all fine in libertarian world, they got shot for trespassing, and now they can just chose to die, *no pressure* (pun intended).
As you can see, my answer starts to take shape:
## Out of system owners deciding to build their own world
**Ships, processing plants and other equipment is expensive. Initial mining was done by ships owned by industrialists form outside the system. Some fat cats residing on Earth or another planet with nice and comfortable 1g surface gravity.** Perhaps ships were automated, perhaps they were crewed by contracted crews. Either way, ships were NOT owned by people who operated them. At first, ships stopped at *von Mises* for fuel, but very quickly gas condensers were built and sale of fuel started, combining both aggressive sales strategies (measured in megatons) and expediency of being able to replace the shuttle with another ore container (I imagine shuttle would usually serve as a lifeboat in case of critical damage, so it's clear that true libertarian would discard it, and loudly complain at any regulations forbidding that).
**With time, some owners perhaps decided that they don't like being subject to Earthen (or wherever they used to operate from) laws, and decided to finally claim the system for themselves. After all, it practically already belonged to them already.** Since *von Mises* is such a hub, with fuel stations and cities housing people maintaining gas condensers already built, using it as base of operations was an obvious choice.
**Because owners are not spacers, they clearly would prefer aerostat**, because it provides some gravitation to stave off all the problems caused by extended living in microgravity, and to separate them from all those *lazy bums who can't just stop being poor*. **That's how *Rothbard city* was built.** What will be the story of its fall?
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It seems to me that it is perfectly reasonable to have a city like this. Your preconditions don't leave open a lot of other options.
**High atmospheric pressure precludes surface construction**. It is not Venus, but a Venus like planet. Meaning the surface will have crushingly high atmospheric pressure. Higher up means a more earthlike atmospheric pressure. Maybe if there is stratification of the atmosphere, the CO2 will be on the bottom and there will be breathable amounts of oxygen up top. Either way, you can't be on the surface and so the option is floating/flying.
**There is a profitable asteroid mining operation in the system, and their system is a choke point.** From the OP. 2 good reasons to be there at all.
**There are no other habitable planets in the system.**. One good reason not to be anywhere else nearby.
So the system is a good place to be, to be in the system you have to be on NeoVenus, and to be on NeoVenus you have to be in the upper atmosphere. All that is left is the structure of your city. I always thought the Cloud City on Bespin was pretty but stupid: that little uvula at the bottom is only some sort of counterweight and it would drift uncontrollably.
If you are going to have a floating city it either needs a tether / anchor, like a buoy, or it needs to be maneuverable, like a ship. You have opted for the latter. Maybe surface conditions are too rough on tethers. High pressure hot acids count as rough.
ADDENDUM: Equinox
I was thinking how nice Minneapolis is in the summer. Not quite as nice in the winter. If only there were some way to move the city so it stayed summer...
That can be the reason your city flies: your planet has seasons and winter is harsh. Twice a year on the equinox the city flies across the planet and takes up residence in the opposite hemisphere, so that the seasons is always spring turning to summer.
Bonus: Equinox is a very cool word and could be the name of this city, or the title of the story.
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## Your reason: Defense
Defense is a very valid reason for this city to exist. If, as you say, the owners regularly make enemies, then living on a planet is a good idea.
Assuming you haven't quietly disposed of the laws of thermodynamics in your setting, a space station will be very visible because of its heat signature. Everyone with a good sensor system will know where it is. In addition, assuming you don't have reactionless thrusters, the space station has limited delta-v and cannot engage in preemptive dodging. This is made even worse if the station is being spun for artificial gravity.
In other words, not only does everyone know where a space station is, they will also know where it will be at any time in the future. An enemy could slam a big rock coated in radar-absorbing materials right into the station easily, without being seen doing so.
On the other hand, the dynastat is constantly moving, and (should be) doing so unpredictably. It is also far harder to spot against the backdrop of nice warm planet, requiring a potential target to approach the planet for reconnaissance. This means, absent planetbusters being used against these guys, an enemy cannot simply fling something at the target from halfway across the system and call it a day. Instead, attackers would have to approach the planet and would be in range of whatever defensive systems the city-owners had, making attacking them far harder.
## Another reason: Politics and Territory-claiming
Basically, it is politically advantageous to have a settlement on a planet for whatever reason. I will list some possible reasons below:
1. The city is technically a colony of some larger polity (which of course requires the planetary presence) which entitles them to some military support in case of invasion. Given how this city is supposed to be hyper-libertarian, I doubt this.
2. According to Space-UN rules, a sovereign nation must have a planetary presence to be recognized. By being a recognized sovereign nation, they gain some benefits in relation to other nations, such as better diplomatic channels or possibly even a free-trade agreement. Or even just being left alone and not being continually invaded by other nations.
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> In other words, what problem was solved by building a large luxury aerostat in a compromised atmosphere, as opposed to a more feasible space harbor or moon-based colony, or choosing some other star system altogether?
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I'll start with the last sentence: Because it would be unnecessarily difficult. There is no reason to leave the star system, if our current one works just fine.
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You already answered this one yourself:
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> Space is fine for the working class, but wealthy people refuse to live in bad gravity.
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Bad (or non-existing) Gravity actually is a thing. Thousands of years of evolution build the human body to be best suited for some gravity. While we are very well able to survive in a space harbor, it takes it toll on the body.
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> I am looking for worldbuilding reasons why this city was constructed.
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The easiest one would be overpopulation on earth. Yes, it's simple as that. It's already a thing to consider at our very time, and your world plays
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> thousands of years in the future.
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A simple reason for it to be build on Venus would be the distance to the sun. I would imagine a city, with the size of an island or metropolis, with thousands if not millions of life ensuring mechanisms, that constantly surfs the atmosphere, requires A LOT of energy. You could say the source for this is sunlight and the city requires such an amount of this, that Venus was the best choice.
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I actually like this idea. I can see some nice advantages to this.
**Gravity**
It is not mentioned if artificial gravity is available, but the city would not need it. Venus has surface gravity of 0.904G which is close enough to Earth for humans to adapt to. This would probably be quite comfortable and it would always work without maintenance, energy consumption, spare parts, technology licensing costs and any other issues artificial gravity might come with.
**Pressure**
At bit over 50km altitude the atmosphere of Venus has roughly Earth normal pressure. While the atmosphere is not breathable having pressure close to Earth normal will make maintaining breathable atmosphere for people much easier and most of all safer. You can maintain same pressure inside and outside and avoid all kinds of issues. Maintain slight overpressure and nothing will leak in.
**Temperature**
The temperature for that 50km given in Wikipedia is 75°C, for 55km it is 27°C. While this is bit high for humans, it is well within the ability of human machinery. While the city will need to expend energy to dump heat into the atmosphere and will require large heat exchangers to do so, it will still be much easier than trying to dump heat into empty space. So your city will have much easier time doing energy intensive processing than space habitats have.
**Volatiles**
The atmosphere will be an easy source for oxygen and nitrogen. The atmosphere of Venus is mostly carbon dioxide so you won't run out of carbon either. Hydrogen is relatively scarce, but it will still be easier to harvest it from atmosphere than from space. On the downside the hydrogen is mostly bound to toxic and corrosive compounds so equipment failures would be quite dangerous.
In fact on Venus you would be flying thru clouds of sulphuric acid, so hydrogen would be easily available and corrosion resistance would be kind of important.
**Aesthetics**
I expect the clouds of sulphuric acid would be kind of pretty, so if this is a vanity project, it kind of makes sense.
**Sunlight**
Venus is closer to Sun than Earth, so you will have plenty of sunlight to grow plants on and to see the clouds by. Venus has fairly slow rotation so your city would be able to stay in the eternal daylight and probably should do so. While there would probably be windows for admiring the view, most of the city would be lighted by fiber optics or artificial lighting for safety anyway, so darkness is one flip of a switch away. No need to move the entire ship to darkness.
The benefit of staying in constant daylight is that it keeps your machines constant temperature to run in which improves reliability. And it gives you constant and abundant source of energy. You'd probably want some sort of backup energy source and possibly you'd have nuclear reactors for industry, but you'd not be relying on a small number of advanced power plants requiring complex components or special fuel. Instead your main power source would be distributed over the entire upper surface and use fairly simple components manufactured locally. And use no fuel.
**Politics**
If all the people on a planet live in your city, you are the planetary government. In most settings and political systems, being a planetary government is a good thing. There might be strings attached, but you will almost certainly be given more freedom to implement your own local policies than a crummy space habitat with the same population. Of course, you'd have more responsibilities and oversight too, but if you just want to avoid interference, and not hide dirty secrets from powers to be, being a planetary government is nice.
If nothing else, a planetary government would almost certainly have a legit claim on all the resources of its star system by convention. A planetary government could also do diplomacy with neighbouring systems on an equal basis.
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**Helium 3 with lots of side benefits**
If the Venus like planet is the only planet in the system or if all of the other planets are gas giants or too far out from the sun or too close in, then it would be a better location for a base than in orbit because an atmosphere would provide shelter from solar radiation as well as a ready source of materials such as water and oxygen. It would make maintenance of internal pressure much easier if external pressure was roughly the same.
If the surface was like Venus then the surface would not be a good location due to temperature and pressure considerations. If the surface was highly volcanic that would make it an even less favourable place for a base and it could provide a city sized variable temperature back drop making the hiding a lot easier especially as the aerostat is moveable around the planet and possibly has the capacity to dive deeper within the atmosphere if need be (within bounds) to help avoid detection.
Being located high up in the atmospher also makes launching into space much easier as there is no need to fight through the dense lower atmosphere.
An added reason why the aerostat should be used could be the presence of Helium 3 in the atmosphere at very low but extractable levels. If this was necessary in fusion drives for the FTL travel then it would be a valuable commodity.
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# Politics
[Current space treaty](https://en.wikipedia.org/wiki/Outer_Space_Treaty) says that asteroids and planetary surfaces are free game, and can't be sovereign. Add to it. make it cover all kinds of uses of space and surface. Add years of treaties, documents, agreements to make it bizarre construction most of our real world international politics is. And then...
## make them "overlook" atmospheric objects.
To an extent it may be the case already. Nations keep jurisdiction on objects in space and on objects on celestial bodies. I agree that this probably also means objects in atmosphere. But we have no precedent. Make it in your world. Make it out of any national jurisdiction as long as it does not touch the ground. No jurisdiction means no taxes, no worker unions, banks that does not report to good old Earth, and many other benefits. Like tax haven on steroids.
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**Fuel Mining**
Let's say there's an aspect to FTL travel in your 'verse that requires the manufacture of a very expensive compound, a key ingredient of which can be harvested from the atmosphere of your planet, call it Element-X
Element-X is rarer than rocking horse droppings, but it's emitted from a couple of huge volcanoes that have been spewing massive amounts of it and other toxic crap into the atmosphere for a couple of hundred thousand years. Element-X breaks down quickly outside of it's natural environment, so your city has to hover directly above the volcanoes as close as possible to maximise the Element-X they harvest. But if it gets any lower then planetary conditions and/or volcanic exhaust compromise the citys infrastructure, it's something they can tolerate for short amounts of time maybe as a defensive mechanism.
Make your city like a vertical tube with the upper end protruding above the atmosphere, this will allow visiting ships to dock without getting too deep into the gravity well or having to bother with rigging their ships for atmospheric conditions or landings. Also makes it a lot easier for those ships to leave.
So your tube city has a figurative and literal upper and lower class. The lower parts of the city won't get much light, that'll be where the heavy industry and harvesting takes place. It'll be a whole bunch of no-fun to live there. The upper sections of the city are where the exotic ships come and go, where the elite work in a bright, bustling cosmopolitan environment. They have the opportunity to travel unlike the "underlings". They'd also be physically closer to any attacks from pirates, so maybe there's an implied historical-societal debt. The "angels" might've successfully defended the city in the past (think Battle of Britain) and aren't shy about using that fact as justification for keeping the underlings in their place. After all, only the elite are smart enough to be pilots, right ?
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There are a few reasons you might have an aerostat city
**Defense**
Your city (assuming the planet has venus like conditions) would be floating around where the atmospheric conditions are similar to earth which is to say a comfortable temperature and pressure which on venus is at about 50 km of altitude which leave a large amount of atmosphere in between you and anyone that may be trying to find you from space. You could also easily design the city to "fall" lower in the atmosphere in an emergency putting more kilometers of hot clouds between you and any observers. You could also use the thick atmosphere to hide uninhabited anti orbital defense weapon platforms deep in the atmosphere floating randomly around the planet. So if the creators of your city were scared of attack an aerostat would be a much better choice than an easy to spot space station
**Safety**
In space if you get shot or someone breaches the outer hull you start to rapidly lose air with no real way of getting it back other than somehow refining it from the minerals around on the surface, or getting it shipped in if your city is not on a planet or moon. In an aerostat since the pressure outside is almost at the internal pressure(and you would want to keep the internal pressure higher than the outside so you would leak out and not let atmosphere in) leaks are much slower on an aerostat and you can relatively easily separate what you need out of the local atmosphere so having leaks in your system may not even be that big a deal. Also if anything fails outside or your aerostat since the outside will be a similar pressure and a comfortable temperature you could walk outside without a bulky space suit, just a tank of air, a mask, and likely some form of full body suit to protect you from anything not good in the air. (on venus this would be sulfuric acid clouds) So if your founders like a guaranteed source of air they may want an aerostat
**Gravity**
Even if your setting has artificial gravity for space borne structures and ships you will need to power it somehow, perhaps your founders saw how much energy it took to run the artificial gravity on space stations with citizens numbering in the millions and decided it would be much better and cheaper to have natural gravity.
Alternatively if you don't have artificial gravity all you have is spin gravity which some people may not like as it's not "real" gravity. Not to mention spin gravity adds a lot of complexity and stress that is a single bulkhead from the airless void
**Refineries**
Most methods of refining metals generate a lot of heat and heat is very hard to get rid of in space so your cities original purpose could have been to refine the metals that the asteroid miners brought in quicker than any space based facilities. Since you also said that ftl takes month I imagine that shipping ore to another system would be prohibitively expensive so why would anyone want to ship unrefined ore anywhere?
**Fuel**
Depending on what you use for fuel in your setting the aerostat may be the only source for it. If ships run on hydrogen they can skim out of the atmosphere of your planet the aerostat and its many defenses may shoot at anyone trying to "steal their air" forcing people to buy fuel from your aerostat which sits on a chokepoint of interstellar trade
**Surface mining**
Just because the surface is inhospitable to people does not mean you cant mine from the surface of your planet, your aerostats could have legions of robots mining valuable ores and metals from the surface of the planet that they can then send up in planes to the aerostat. It would be much more costly to launch all the goods to orbit from the ground through all that atmosphere and against gravity. Also you could have large pipelines running from your station to the ground pump stations to siphon oceans of (depending on how horrible it is at ground level) oceans of acid, metals, or something more exotic.
**Tourism**
They actively encourage people to come see their glorious city floating in the clouds, see sights that you can't see anywhere else in the galaxy. You can do things that are impossible anywhere else, go base diving in the clouds, rent a glider and fly around the aerostat, take advantage of the lax drug and weapon laws, experience their luxury spas, etc. Or alternatively advertise that anyone can start a business on the aerostat, that your ability to move up in society is solely based on the amount of profit you make, you have the best universities and labs in the sector and there are always rich people willing to finance novel science tests. (also again the very lax laws on human testing may attract some less than reputable scientists)
**Terra Forming Legalities**
The elites living on the aerostat want to terraform the world into a veritable eden, but according to interstellar law no one may claim land on a planet/moon/asteroid they do not have a physical presence on and unclaimed land may be claimed by anyone who is passing by that wants to set up. So to ensure they have claim to the world under interstellar law they established a physical presence (the city) and of course these elites who want to claim the entire world don't want to live like the common people in the gravity less and dangerous hell of a space station they made the aerostat a luxury resort for themselves and added any of the above industries because why not make more money while we wait for our investment in real estate to pay off
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A hypothetical species is divided into males and females that exhibit pronounced sexual dimorphism. The males are further divided into multiple morphs (e.g. α-male, β-male, γ-male, etc). This polymorphism is extreme enough that a viewer unfamiliar with this species could mistake all these morphs for different species. If the species were to possess human-like intelligence, they might treat these morphs as separate genders (e.g. aqir, qntal, guqin, etc).
What selection pressures would favor such polymorphism?
EDIT: Reproduction is a simple matter of a male inseminating a female. At some point selection pressure caused the males to diverge into multiple morphs. Differences between the morphs are as extreme as those between dog breeds. The details are deliberately vague so that this question could be applied to plants, fish, mammals, etc.
EDIT: I do not mean to imply that morphs are necessarily hereditary or limited to a specific number.
[Answer]
There exists a somewhat analogous situation to this in lizards, with 3 males that have different appearance, though they are not so drastically divergent as to be unidentifiable.
In this case they system works, and stays stable, because they are playing the evolutionary equivalent of rock, paper, scissors. Each male 'beats' one other males morphology when it comes to competing for mates, but they are equally beaten by the third male. Every generation one of the male morphology will have had more success then the others in reproducing, lets say your α-male, leading to many of α-male existing in the current generation. However, since another type of male, lets say β-male, is better at securing mates when competing with the far more common α-male these β-male will secure more mates in the current generation, leading to more β-male in the subsequent generation. That generation, now full of β-males, will in turn see the γ-male successfully out compete for mates with the common β-males. This finally sets the α-male up to make comeback in the subsequent generation since they can easily out compete with γ-male.
In lizards these males could be looked at as standard, harem, and sneaky males, based off of their mating strategies. The 'standard' males are exactly that, normal sized males that will compete for rights to mate with each female as it finds as most lizards do. Harem males are larger then standard males, and can easily best standard males in a fight. These males collect a large number of females together into a harem and guards them. When standard males are common the Harem males can easily beat the weaker harem males in fights, allowing them to secure large harems with minimal competition and thus secure numerous matings, effectively out competing Standard males.
Sneaky males are in turn the kryptonite factor of Harem males. These sneaky males are weaker then both other types of males, but they are fast and have a different mating strategy. Rather then fighting the much stronger Harem males they allow the Harem males to collect females into one place and then sneak into the harem to mate with the females while the Harem males are distracted defending their harem. When Harem males are common these males spend most of their time competing with each other to try to secure large harems, leading to increased injury and death amongst harem males and lots of females in one place for the sneaky males to mate with during the distraction. This results in the sneaky males producing the most young in the subsequent generation.
Unfortunately for sneaky males they can not defeat the other two males in a competition. Once sneaky males dominate they will not be able to find harems to sneak into, and instead will face standard males who can defeat and drive away sneaky males to secure mates, but never collect a large enough harem to allow a sneaky male to secure a mate while they are distracted.
A few different species of lizards demonstrate this pattern, and it has proven evolutionary stable. Males of every morphology secure mates in every generation, but the fact that each male 'beats' another male in competition prevents any one type of male from winning the evolutionary arms race, the more common any one gets the better off their counter male morphology becomes.
You could do something similar with your males. The only catch is that you want your males to be significantly different, while the above males have a less drastic morphological difference. My suggestion would be to make the males niche be more then just mating strategy. Each male is evolved for a specific niche of habitat or prey as well, developing more drastic changes in morphology to fit that niche; but still keeping the concept that one one morphology grows more dominant another will benefit from it.
One example I can come up with is that they prey on different levels of the food chain. α-male are larger, and eat a larger carnivorous species. β-male are smaller and eat a species that is preyed upon by whatever α-males eat. Thus when α-male are common there is more food available for β-male's because the β-male don't have as much competition for resources now that α-males are eating the other major predator of β-male preferred prey. In turn perhaps γ-male evolutionary niche depends on the prey species of β-male being less common. Maybe γ-males prefer some resource or living condition that the prey of β-male also prefer so that they can flourish once β-male remove their competition.
perhaps γ-males in turn build damns that change the nature of river above and below the river, creating habitat changes that make the species α-male prey on more common to complete the rock-paper-scissor dynamic.
If you make it so that these males have evolved to benefit from another type of male being common in multiple ways, benefiting in mating strategy as well as niche or presence of their prey species, you may be able to create a niche that is unique enough for each male to justify radically different morphological, but it would take a bit of thought to ensure the niches are unique enough to have each male look completely different from the other male while still having them keep the rock-paper-scissor dynamic *and* sharing the same rough habitat location (they are still competing for same females, so they must all live close to those females to compete for them)
I'd also mention that the female has to be able to produce the young of each male. if the males are different enough it becomes hard to believe that they are all capable of successful mating with the female. For that reason id suggest making all the males still have a fairly similar physiology. Perhaps the look different due to a comparatively superficial outward difference, most obviously their pelt/camouflage used to sneak up on their preferred prey, such that they can still be physically rather similar while still having very dynamic differences.
[Answer]
Sounds a lot like the [Ruff](https://en.wikipedia.org/wiki/Ruff). There are three different male morphs:
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> Three ruff male types. On the left side a faeder, in the middle a satellite and on the right site a territorial. Ruff and head tufts may have black, brown, orange and white colors. In satellites either ruff or tufts normally are pure white and they lack black feathers.
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> [The faeder identity](https://www.willyvanstrien.nl/pdfs/engelspdfs/the%20faeder%20identity.pdf)
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It's genetically determined, and **each one has a different mating strategy.**
Most of the males (85%) are territorial. They stake out their claim on the lek (the mating arena) and wrestle with their neighbors. Satellites (15%) are not looking for their own territory. Instead, they join up with a territorial male. The females, you see, are looking for a show: the two males "give a show of courting and mounting each other". And then there's the faeder, which is very rare. It's funny you would mention gender identities, because faeders look female and hide their maleness during mating season:
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> Infrequently a female crouches for a faeder to solicit a copulation from him. If she crouches to be mated by a normal male, the faeder tries to slip between that male and the female and to mate her sneakily. And often, if the female thereafter crouches for another male, the faeder quickly crouches for that male too. Embarrassed by this double invitation, the male may mount the faeder rather than the female. The faeder in that way decreases the chance that his sperm will have to compete with that of another man.
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[Answer]
There are several examples of alternative mating strategies leading to different morphological traits among males in the same species. For example the horned beetle *Onthophagus acuminatus* has two different male morphs that pursue two different mating strategies. Healthy, well-fed males develop large horns which are used to fight off other males in order to secure mating partners. Males who developed malnourished forego growing horns because they won’t be able to compete with well-fed males and instead attempt to sneak around them. These beetles dig tunnels into dung balls and the horned male stands guard at the entrance of the tunnel, preventing other males from entering. The hornless males dig side tunnels that intersect with the main tunnel allowing them to slip past the male guarding the entrance and mate with the female. An example [schematic](https://www.researchgate.net/profile/Douglas_Emlen/publication/225738217/viewer/AS:104328413057032@1401885240452/background/3.png).
In case you think think is just weird invertebrate stuff [orangutans](https://en.wikipedia.org/wiki/Orangutan#Reproduction_and_parenting) also actually have male morphs with similar reproductive strategies. After reaching sexual maturity some male orangutans will begin to develop flaps of skin on their cheeks. The cheek flanges are hallmarks of fully developed males, but some males will remain in a juvenile, unflanged state for many years. This “bimaturism” results in two morphs with different reproductive strategies. The [flanged male](https://orangutan.org/wp-content/uploads/2010/06/behavior-3.jpg) is territorial, attracting females and warding off other males with loud calls. The [unflanged male](http://ichef.bbci.co.uk/wwfeatures/wm/live/1600_900/images/live/p0/36/cx/p036cxyg.jpg) is nomadic and will follow females around attempting to mate with them.
Your requirement for 3 separate morphs reminds me of [Paracerceis sculpta](https://en.wikipedia.org/wiki/Paracerceis_sculpta). This species has 3 distinct male morphs with 3 different mating strategies. The large α morph fights for females and creates harems of them. β morphs are smaller than the α morph, and instead mimic the appearance of a female. Using this disguise they infiltrate the harem to mate. The γ morph is even smaller than the β morph and uses its small size to mimic a juvenile and escape detection.
As your species gains in intelligence over evolutionary time it’s likely that these roles might fall apart. The example of the orangutans should illustrate that these strategies can still be effective even in fairly intelligent animals though. As your society develops perhaps the role of female choice, or of more equitable sharing of reproductive rights, helps keep all of the male morphs competitive.
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What you're describing sounds a lot like bees, ants, and other colony species, that use extreme heteromorphism to specialize into different roles. As for what selects for this, I'm afraid I don't know off hand.
If you have specific ideas of what each morph would be like, that would help to determine what kind of selection pressures would be involved, but if they're like ants I'd assume they all work together as cohesive units.
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The thing about being different, is that one of these Male Genders will objectively be better at securing the average female than the others, and will come to dominate. There needs to be a way to balance that out, or it will happen. One very good reason could be a kind of Horizontal Caste system.
With the Horizontal Caste system idea, each kind of Gender (alpha, beta, etc) is naturally very adept at certain kinds of tasks, which hare very different from all the others. Warrior Genders, Worker Genders, and whatever others you want. This leads to 2 results, Either one, the Caste system tips vertical, and we get Hindu Brahmans, who think they are better than everyone else, and treat the other genders badly, or two, they become very cooperative, and keep it mostly horizontal. They recognize that each one can't get things done without the others, and so they naturally group up to do so.
Lets throw out the Vertical Caste system, and say they went to the second option. This one is also the more likely option, Since the one Caste is truly unable to support itself, even if it had to. Different Castes specialize in what they do best, and work together to make the city run. Say Warriors are the Police, Fire Department, and Heavy lifters, while Workers are the coordinated and precision workers, who work with the Heavy lifers to get things in place. They might also be the ones who can work technology the best. Perhaps you also have Manager Caste who are great at planning and abstract thining, and the Leader caste, who are great at empathy and have lots of Charisma. The Leader and Manager can together work out a plan that is the best for everyone, then they have the Workers execute the plan, while the Warriors do the heavy lifting and protection.
Using this kind of system, the need for each gender will wipe out most segregation issues, and the lack of ability to do other things will cause them to group up and live with several individuals of the other Castes. Since each Caste can't do many things that may be critical for it to thrive, they will search out and make friends with the other castes to help them do those things. This will lead to tendencies for Romantic couples to be of different Castes, which will let diverse children be likely in most genetic scenarios.
The most obvious problem with this kind of system is that it can become unfair. Obviously, costs and workload are going to be different between the Castes, and some will view it as unfair. This can only be Mitigated. One good method to do this is to abuse their mental value of the tasks the others do. Managers are amazed at how Warriors can carry big things so easily, while Warriors are always amazed at how things keep working out if they do what the Managers ask of them, regardless of how strange those requests seem to the Warriors.
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[Question]
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I have a creature capable of absorbing all energy to feed itself. So efficient is it at doing this that the creature itself appears utterly black, since it absorbs all visible light. Its eyes are like deep voids.
Even a spear thrown will impart kinetic energy, which the creature will use, and the creature can then convert the spear to energy and consume it. The creature is something of an energy vampire, it can suck the energy out of anything.
It can control its absorption of energy and redirect/output anything absorbed, thus allowing it to reproduce, fend off an attacker, etc.
How could my protagonists defeat such a being? Have I made it too powerful?
Notes: Magic is available, and so is advanced scientific knowledge. One of the protagonists is from an ancient race that has faced the evil before. One of the protagonists is a warrior. They're on a magical world, and don't have time to build an advanced scientific apparatus.
=== UPDATE ===
There's a lot of great ideas being given. Some of them I can't use, since I'm writing and releasing my story in serial fashion, and certain parts are already out.
The approach I'm going to take is this (which is a kind of amalgam of several suggestions):
1. My sciencey character (he's a universe-hopping teddy bear, don't ask) will rush to build a portal. The portal will link to a negative-energy/zero-space universe, which will eventually kill the creature.
2. My wizard will use a variety of energy-sucking spells (cold, etc), to draw energy away from the creature (which is currently partially imprisoned).
3. My warrior will break the seals of the prison and act as bait, leading the creature to the portal.
4. An army of squirrels (it's... complicated) will complete the process by forcing the creature through the portal.
With all the good suggestions made I'm having difficulty picking one to accept. So I'll leave this open for another couple of days, and then pick the answer with the highest votes.
So to everyone: vote for the answer you like best. :-)
[Edit] In my story I had the protagonist open a portal to a "negative energy" universe, where the universe itself would suck energy out of the creature, killing it. Many great ideas in this thread. Thanks all. :-)
[Answer]
Before we start note that the most realistic questions have the most realistic answers - and vice-versa. You may not find a [science-based](/questions/tagged/science-based "show questions tagged 'science-based'") answer simply because the question is not [science-based](/questions/tagged/science-based "show questions tagged 'science-based'").
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## **Attack stealthily**
These creatures must have biological systems to prevent death from all the energy they contain - or systems to harvest the energy in the first place. Consider implementing a mundane method to weaken these systems if the individual isn't aware that something's going wrong - have your heroes sneak up behind them and stab the organs that have these functions. Suicide? Maybe. Consider throwing knives or quiet projectiles.
## **Fight fire with fire**
In any intelligent population, there will be organisms that don't agree with the rest. Consider recruiting "good" evil monsters of absorption.
## **Drain them with something else**
If it's possible for a creature to suck up all energy (in your universe), why can't there be something that does that too, but *better*? Perhaps there's some ancient mage, ritual, mineral, or even *parasite* of the 'feeders' with the power to drain the energy from around them faster than they can take it back. These should be less common than the feeders, and perhaps guarded by them, to balance the narrative.
## **Starve them**
A couple other answers mention this. Create a container so durable that if the creature fully releases their energy, it cannot break. Note that there should not be any lights, sounds, or even strong gravity present. The ideal prison of this kind would be a completely [isolated system](http://chemistry.about.com/od/chemistryglossary/g/Isolated-System-Definition.htm), which is not economically viable to make (even if you figure out the physics behind it)
## **Overwhelm and engorge them**
You mention in a comment that "`a single one of these creatures can absorb the energy of an entire planet and still feel hungry`". Luckily, there are some *pretty* powerful stars, pulsars, and black holes out there. **Even if** energy input can be controlled, there is bound to be a limit of how much energy these things can shut out - eventually, the nearby heat, gravity, radiation, etc. will be too great to overpower. This *does* require containment, which could be done using any of the other methods listed.
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The proper way to defeat such a foe is patience. As you noticed, you can't simply strike out against it, for it will absorb the energy and become more powerful than before.
However, this isn't all that different from any other living organism. We all consume what energy we can, and redirect it. The only different seems to be the magnitude. This creature has refined the art.
The solution is to use its own hunger against it. If it is hungry, it has a desire to have more than it already has. This can be used against it. All you need to do is lure it. Give it the illusion that there is energy available to consume, but just out of reach so that it has to expend energy to reach out and grab it. When it does, simply make sure there's less energy there than the creature spent reaching for it. Each time you do this, it becomes a little weaker.
In many martial arts, there is a concept of "emptyness." Your goal is often not to subdue an opponent, but merely to be empty wherever they strike. If the opponent believes they have found a valuable weak spot, they will overextend in order to capture it.
The essential skill for such a fight is to be calm and still. Never give the energy consuming enemy more energy to work with than absolutely necessary.
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Since magic is available, some kind of cell made from a null energy vacuum that can imprison it. If it needs a constant stream of energy, then locking it away for a short period of time might be enough to starve it to death.
If that doesn't work you could look for a way to turn it's metabolism up to 11, so that it burns energy faster than it can possibly consume it. Then it will be starving to death even as it tries to consume everything around it. It will cause a huge amount of damage during this period, so you probably want to invoke it somewhere away from populated areas. I imagine down in a cave (no light, not much heat, etc). This will have an added benefit that it won't be able to spare any energy for attack or reproduction.
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It all depends on how your magic works, really, but most magical systems have some equivalent of *cold spells* and *energy drain spells*. These would be the most effective against your monster.
**Cold spells**, by definition, are extracting energy (heat) from their target, not adding it, normally by transferring that energy into the surrounding environment and heating the surroundings.
**Energy drain spells** do the same kind of thing, without the explicit focus on draining heat energy. Often it's a rather hazy "Life energy" that reduces the target's health and heals the spellcaster; this would be another option for getting energy out of the monster.
Some magic systems also suggest that **fire spells** work in reverse fashion to cold spells, drawing energy from the environment and focusing it into a single spot; if you can focus where you're drawing the heat from, a flame spell would also be capable of drawing energy away.
[Answer]
## Yes, you have made it too powerful.
The main problem is these points:
* "the creature can then convert the spear to energy and consume it"
* "It can control its absorption of energy and redirect/output anything absorbed"
If it can convert mass to energy this makes all other energy absorption abilities redundant. Lets say a spear weighing 3 kg is converted into energy according to:
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> e = mc^2
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That's about 75 TWh of energy, enough to power the entire current world for 6 hours. The kinetic energy of the spear and any such does not matter on this scale.
If this being is in contact with any matter it will have access to endless energy. Releasing just a minuscule fraction of the energy of that spear as a pulse of pure heat or radiation will destroy any kind of opposition that would be on a spear-throwing-level of technology (or any other level for that matter).
If it consumes a small hill it will have enough energy to toss the Earth out of the solar system..
Drop abilities that involves converting matter to energy.
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Does the energy being have a limit of how much energy it can take in? If so, you could surge it with thousands of volts before it has time to adapt and then it could A) blow itself up or B) simply disperse.
Perhaps you could also make a fictional energy vacuum for your universe.
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Here are a number of possibilities. However, some of them may require the animal to be drained of energy before attempting them, so that it cannot vaporize or otherwise thwart the attempt with energy release.
* **Suffocation:** Perhaps it could be suffocated.
* **Infection:** It seems the creature would still be vulnerable to biological attacks.
* **Poisoning:** Toxic or sedating poisons could possibly be used. Gasses could be non-impact methods of delivery, and misting it with poisonous liquid might also work.
* **Permnent Immobilization:** Perhaps it could be frozen in [carbonite](http://starwars.wikia.com/wiki/Carbonite), or entombed in a substance which cannot be vaporized by energy release.
* **Endothermic Attack:** Possibly a sizable enough [endothermic](https://en.wikipedia.org/wiki/Endothermic_process) attack could starve it.
* **Decompression:** Sudden decompression, as would occur in space, could possibly kill it.
* **Freeze It:** Possibly freezing the creature in the near [absolute zero](https://en.wikipedia.org/wiki/Absolute_zero) of space.
* **Antimatter:** Perhaps the creature would be vulnerable to [antimatter](https://en.wikipedia.org/wiki/Antimatter).
* **Anti-energy:** E=mc^2 means all matter is essentially energy. Extrapolating from that, perhaps all antimatter is essentially anti-energy. Perhaps anti-energy would be poisonous to the beast.
* **Spatial Loop:** Perhaps the protagonist could get a [Handheld Portal Device](http://theportalwiki.com/wiki/Handheld_Portal_Device) like the ones in the game [Portal](https://en.wikipedia.org/wiki/Portal_(video_game)). Then, create an entry portal below the monster that teleports it to the exit portal directly above the entry portal. This would cause the monster to just fall through the portals for all eternity, or until the portals were placed elsewhere.
* **Temporal Loop:** Perhaps the creature could be caught in an infinite one second loop, forced to constantly live only that one second over and over again.
* **Temporal Acceleration:** Perhaps a spell that causes the creature to age so quickly it dies before it can do harm.
* **Launching It on an Unobstructed Path in Space:** Perhaps it could be launched into space on a trajectory such that it will never colide with anything. Perhaps magic could be used to create such a path if a natually occurring one cannot be found.
* **Infinite Shear:** Perhaps if the creature were sent into a black hole, the infinite shearing of it's physiology at infinte speed could be too fast for it's nervous sytem to respond to, thus not allowing it to maintain physical integrity even though it can expend all the energy.
* **Stupification:** Perhaps it could be trapped in an endlessly looping mirror maze so completely unlike anything it has experienced before that it cannot understand how escape.
* **Cognitive Overload:** Perhaps it could be given temporary perception of all of infinity. I saw that in a comic book once and the infinity was so overwhelming to the character's limited human consciousness that the character's psyche was completely broken, leaving him a vegetable.
* **Befriending:** Perhaps your protagonist could befriend it by finding something it likes & giving it to it.
[Answer]
I'm going to have to ask for some clarification here. For one, if it absorbs all energy how does it sense its environment? If it absorbs all energy how does it move? Propulsion in an action-reaction pair from Newton's third law, which imparts a transfer in energy.
Without knowing the above I would have two thoughts. The first is it is fairly common to have magical rituals to gather energy for some purpose. Could your heroes repurpose some ritual to drain energy from the monster? Perhaps it needs some focus, like an amulet that the warrior has to keep near the monster while the ritual is performed by the ancient race hero.
Otherwise, the classic way to deal with such monsters is overloading it with energy. Beware the result, however, at high enough energy levels you'd get either a massive explosion or a collapse into a black hole.
[Answer]
Since all creatures have to use energy, I have outlined two possibilities. The first outlines a scenario where it cannot absorb its own energy, and the second outlines a scenario where it can.
**Make like Sir Robin and Run Away**
This may not seem like the most interesting solution, but its a pretty clever way to outsmart it, based on my understanding of the question.
In order for the creature to move, the creature has to exert force and thus use energy. For this creature, energy seems to fuel two purposes, being both the traditional form and its food.
If you get the creature to exert enough energy to try to catch the heroes, without applying any back on to him, even with the light energy he will slowly start to starve to death. And so of course, the easiest way to do this is to run away and have him chase you.
This still can be interesting from a story perspective, because it would require the redirection of the creature by the heroes to ensure it doesn't come into contact with energy.
**Do the Exact Opposite in the Same Way**
Essentially, all of my reasoning is the same except this scenario operates in a world where the energy the creature can be re-consumed by the creature.
Again, you have your heroes run away, or perhaps use magic to teleport him to a deep part of space. All you have to do is get the creature to a place where there isn't another form of energy acting on him. Atomically, energy is everywhere, but for the sake of the story I'm assuming its things you can normally think of as energy.
Once this is done, the creature is forced to constantly exert and consume energy, creating an Ouroboros Effect that essentially traps the creature.
The interesting things about this scenario are
1. Its a lot cooler than running away until the beast starves
2. It sets up for a continuation later. Perhaps the creature is in the deepest reaches of space or the lowest depths of the world, but should someone come across it and accidentally exert energy, it would be free from its prison of eating itself.
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If it sucks energy it must be storing it somewhere. You could poke holes in it so it looses containment of it's energy.
I get that if you throw a spear at it, it can absorb the kinetic energy, but what happens if you just stabbed it slowly? What happens if it doesn't know it's getting hit by a spear?
When I first started thinking about it, I thought this thing sucks energy, so it has negative energy, negative + positive = 0, so that should take care of it. But that's not true, the being isn't net negative. It appears black because it takes in energy, so it's an incredibly energetic being, very net positive. So the opposite of that would be something actually negative. He sucks in energy, yes, but he is made of energy? maybe? so if you could actually produce negative energy, like a higgs field at 0, then you could still hurt it.
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What does your creature do once it is "full"? Does it cast off the energy some how? And at what rate? How does it release any byproducts from energy conversion? Humans defecate/urinate/exhale.
The point of all my questions is to trick the creature into converting energy because it's being fed at a comfortable rate and then suddenly ramp it up 100 fold. This would hopefully take the creature off guard and it would consider absorption to the point it is too late and "pop" the creature explodes.
[Answer]
Simple,and this might seem bad, stupid or weird, but trust me. If this creature takes all forms of energy and converts them for itself, you have to deprive it. Though this was previously mentioned,this is for a worst case scenario. IF magic is available,then you need to :
1st:find a material that will either
A]impart no energy
B]REMOVE energy
Assuming you have magic, where there is a will , there is a way.
2nd:you must find a way to remove all sources of energy from a room made of aforementioned material, which presents a challenge. If this creature absorbs all energy,it would absorb even kinetic energy from air molecules. Now, unless there is some unobtainium anti creature/weapon, this seems like the creature would be too overpowered. This presents a few choices:
1:Remove some powers
this could be done by limiting what type of energy
2:An anti creature/object
In speculative physics there is a white hole, if there is a black hole creature,make a white hole object/creature, the specifics on this i am not too sure of.
TL;DR:
1:make the creature less powerful.
2:make an opposite
[Answer]
Throw a star or two into it and it will exceed the threshold and become a black hole.
If he can selectively absorb energy to feed itself, it will try to avoid becoming a black hole by blocking some of the energy instead of feeding off it. So, weapons will be able to hit it while its "feed off energy" behaviour is offline due to overload. If instead it chooses to absorb the matter thrown into it, or is unable to prevent this, it will become a black-hole and collapse.
Problem solved.
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My answer for this question is to use magic... specifically time magic
This creature can be starve with right application of time magic. I doubt it would survive in a time capsule that has its time bubble accelerated to million years per second... It is a living creature thus it needs sustenance... the passage of time is your friend in this case
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If you have magic, this monster need only ONE weak point: **air**
use a spell to drain all air around him, create a vacuum and problem solved!
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Gravity-manipulation attacks. Something like the Mass Distortion spell from Might and Magic that greatly increases the recipient's mass, causing its internal structure to collapse in on itself.
Freeze it. Cold temperatures are by definition the absence of heat energy, which means you will cause damage that's physically impossible to absorb. Use a cold beam or "freeze ray". Most importantly, do NOT use a matter-based freezing approach (such as pouring liquid nitrogen on it or casting Rain of Icicles), because it will simply convert the nitrogen or water in the icicles to energy via E=mc^2.
Alchemical approaches that transmute its molecular composition to an unfavorable or inviable configuration with the same amount of chemical potential energy.
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[Question]
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I'm in the middle of creating a RPG one-shot for some friends, and I'm thinking of doing an *Aliens* meets *Space Hulk* style "Big-Gribbly Aliens VS Humans" game.
Is there an upper limit to the size of a craft with centrifugal style gravity? I've only ever seen them in fiction presented with single floor pods or rings around a central hub. You can obviously get more floorspace by creating a cylinder around the central spire, but could you go out and create more floors?
If so, would this alter the relative gravity per floor, and by how much?
(tagged with "Science-Based" as I'm not sure how "hard" the centrifugal gravity concept is)
[Answer]
That is certainly possible, and enough science fiction settings cover them.
* The centrifugal force depends on [the radius and the rotation speed](https://en.wikipedia.org/wiki/Rotating_wheel_space_station). It is proportional to the radius, so a ring with a large radius allows several decks with very similar "gravity."
* A large diameter allows a low rotation speed, which means less distraction through the coriolis force.
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**Follow-Up:**
Imagine a cylinder with a diameter of 40 m (i.e. a radius of 20 m) that rotates three times a minute. You stand on the inside of the cylinder. You would move at 6.3 m/s and feel 0.2 g.
* If you walk spinward around the cylinder, you will feel more than 0.2 g.
* If you walk antispinward around the cylinder, you will feel less than 0.2 G.
* if you walk parallel to the axis, you will feel 0.2 g.
"Up" will always be towards the spin axis, but the little changes can make you dizzy.
So the direction of movement on the same deck changes the felt gravity.
* If the deck height is 2 m and you stand one deck higher, you will feel only 0.18 g.
[Answer]
I highly recommend reading
[O'Neill, G. K: The Colonization of Space, Physics Today, vol. 27, no. 9, Sept. 1974, pp. 32-40.](http://www.nss.org/settlement/physicstoday.htm)
Up to 16km radius is doable with usual materials. Conservative with old steel (1920) 3.2km
[](https://i.stack.imgur.com/A8lIx.png)
$\tiny \text{Source, O'Neill, G. K: The Colonization of Space, Physics Today, vol. 27, no. 9, Sept. 1974, pp. 32-40.}$
>
> One foreseeable development is the use of near-frictionless (for example, magnetic) bearings between a rotating cylinder and its supporting structure, which need not be spun. For eight tons per square meter of surface density and a tensile strength of 300,000 psi, R would be 16 km, the total area would 50,000 km2, and the population would be between five million (low density) and 700 million (the ecological limit, the maximum population that can be supported).
>
>
>
This is with common materials, with 1g, and normal pressure.
The internal pressure of air is a big part of forces, and if it will be 1/3 of normal (used in some spacecraft's), and 1/3g (mars like) - it will be bigger, 3 times at least.
The main problem here is this surrounding external supporting structure(how much material we may have) and interaction of internal structure with that external one, bigger is radius bigger is the difference in speeds between internal and external structure(there are some tricks though).
With stronger materials, not know at that time 1975, structure may be bigger, linear proportion here 5 times stronger material, 5 times bigger radius.
With the strongest material as we know at the moment(>100GPa), it may be 100 times bigger - so 320km radius (or bigger with 1/3g and 1/3 pressure)
But that's still not the limit, but probably good enough for *the size of a craft with centrifugal style gravity*.
A rough estimation of limit is actually external structure and it's ability to hold 1bar pressure. And roughly there is a linear proportion between thickness of walls and radius of cylinder, more complex internal structure of cylinder also may help (remove pressure of air stress to walls - tethers inside with central axis - so making cylinder itself more robust helps)
The cylinder is more limited with the material strength we have and the amount of that material, and our wishes to move so much material.
## P.S.
[Here](http://settlement.arc.nasa.gov/75SummerStudy/Chapt4.html#Shape) is some NASA stuff, about choosing sizes, masses of possible habitats, crew. It's from [Space Settlements: A Design Study](http://settlement.arc.nasa.gov/75SummerStudy/Table_of_Contents1.html) broader and more practical overview of that topic.
[Answer]
Tom McKendree came the conclusion that an O'Neill-style cylinder constructed with [carbon nanotubes](http://www.zyvex.com/nanotech/nano4/mckendreePaper.html) could have a radius of approximately 461 km.
[Quoting the above](http://www.zyvex.com/nanotech/nano4/mckendreePaper.html#RTFToC18) (footnotes omitted):
>
> The maximum radius of such an O'Neill style colony is limited by the hoop stress of the spinning structure, and the tensile strength to density ratio of the material. The formula is
>
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> $$R < \frac{HoopStress}{gG}$$
>
>
> Where R is the radius, g is the acceleration of pseudo-gravity at the rim, and G is the density. [Molecular nanotechnology (MNT)] offers a 5 x 10$^{10}$ Pa tensile strength. Using the design rule of 50% safety factors for O'Neill style colonies, a 3.3 x 10$^{10}$ Pa design tensile strength is reasonable. The associated material density is 3.51 x 10$^3$ kg/m$^3$. One goal of the architecture is for g to equal 9.8 m/s$^2$. This all gives a possible space station radius of 9.6 x 10$^5$ m, or nearly 1000 km. For comparison, the corresponding feasible radius for titanium is 14 km, and even at its ultimate tensile strength with no safety factor, the titanium limit would be 23 km.
>
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> At the 9.6 x 10$^5$ m radius, the entire available strength (at the safety factor) of the MNT-based material is being used to prevent the rotating structure from bursting, and there is no strength left over to hold the space station's contents, including an atmosphere. To do so, a lower radius must be set.
>
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In the section immediately following, McKendree arrives at a radius of 461 km when atmosphere and fixtures are accounted for:
>
> One can directly solve for the structure radius where the shell is 5000 kg/m$^2$. Using MNT materials, the structure will be 461 km in radius. For comparison, the equivalent number for titanium is 6.6 km, or for a titanium shell is at its ultimate tensile strength with no safety factor, 11 km.
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[Answer]
A number of sci-fi space colonies use the rotating cylinder concept, with an implied diameter of a few kilometres. For a 3km radius cylinder, Earth-like gravity would require a rotation rate of about 1 spin per 110 seconds. Rim speed for the cylinder is a bit over 170 m/s.
Apparent gravity variation is directly proportional to the radius, so a few tens of metres up or down out of 3 km isn't going to make a huge difference.
The Ringworld (also echoed in the Halo game concept) uses a giant ring millions of km across. Rim speeds are ridiculous, and material stresses in the ring would be infeasible in real-world materials.
[SpinCalc](http://www.artificial-gravity.com/sw/SpinCalc/SpinCalc.htm) is useful.
[Answer]
Yes. The material strength needed goes up with the radius. Eventually you can't hold it together.
You can create a modified version, though--the strength is all in an outer non-rotating shell, the station rotates within this on a maglev system. Even this will eventually reach a limit as you can't support the floors (just like there's a limit on how tall a building you can build.)
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[Question]
[
It must be very dark and hot on the surface of Venus, but my humans want to change that and make a Venusian colony. The problem? The extremely thick atmosphere would make it problematic to say the least. There would be a contest between heat and atmospheric pressure to see who can do the colonists in first. The colonists solution? Send atmospheric drainage ships into orbit around Venus and extend a giant robotic [Proboscis](http://en.wikipedia.org/wiki/Proboscis) into the Venusian atmosphere.
The gas from the atmosphere will be drained into massive "Drainage Ships" that will be sent to Mars to add some of the atmosphere to it. The rest will be sent away, out of the Solar System. Since Venus is in inner fringes of the habitable zone of our system we can now place a permanent colony on Venus.
Is this realistic? How could I make it more realistic?
[Answer]
Venus is a great place for a colony as long as you don't put it on the surface.
About 50 km up the atmospheric pressure is the same as that at earth's at sea level. The temperature at that height there is like the south of France. As a bonus on Venus Air (the stuff we breath) is a lifting gas. Because of the surface albedo solar panels work as well on the bottom and top of your balloon.
There is also a fantastic amount of carbon for making plants and carbon-based tech. The water problem at least for a limited colony could be solved by acid harvesting H+ for the taking.
[Answer]
I proposed something like this in another question, but it might work better here.
Put something in orbit between the sun and Venus to cut down on the amount of sunlight. If you can block it completely, then the atmosphere would basically freeze, and you'd be able to scoop it up or seal it away.
The original suggestion was for some kind of soletta, kind of a giant solar umbrella made from solar sail material, but it would have to be very very big. Other ways that might work would be to ring the planet with a dust cloud, or possibly a cloud of small solar sail satellites, which would reflect the solar radiation and heat away. They could even collect the energy and beam it down to the planet to power the teraforming. When the work is done, you remove some of the satellites/cloud to bring the temperature up to the point you want it, while still keeping it cooler and cutting down on the radiation.
[Answer]
The [atmosphere of Venus](http://en.wikipedia.org/wiki/Atmosphere_of_Venus) is a nasty place. The surface is 900 degrees Fahrenheit at 100 atmospheres of pressure. The upper atmosphere has constant winds exceeding 200 mph and sulfuric acid clouds. The major constituent is carbon dioxide, with trace amounts of noble gases, water vapor, and corrosive sulfur-containing compounds. Ingesting this stuff into your spaceship would probably be a bad idea, as would dumping it on Mars.
Note also that removing the thick clouds (again, make of friggin' *acid*) would expose the surface to intense solar radiation, as Venus's magnetic field is much weaker than Earth's; probably also a bad idea.
(Side note: there would be no contest between temperature and pressure. The later Soviet [Venera](http://en.wikipedia.org/wiki/Venera) probes were all done in by the high temperature. It is easy to build something that can withstand thousands of atmospheres of pressure [think of deep-diving submarines], but much harder to make something that can survive a bath in molten lead [and even higher temperatures].)
[Answer]
## The Bosh Reaction
The [Bosh Reaction](https://en.wikipedia.org/wiki/Bosch_reaction) lets you turn hydrogen and carbon dioxide into water and graphite. Just by adding hydrogen to Venus, you destroy the atmosphere and create a huge ocean and several meters of ash will cover the ground like snow. The huge amount of graphite might not be desirable, but Venus has basically no water on it, so the new ocean would be appreciated.
### Why it is good
I think it's an excellent first step for terraforming Venus. You would have to take huge volumes of hydrogen to Venus, but that's much easier than transporting CO2 away. You'd need in the neighborhood of twice the volume of Venus's atmosphere, but only 1/40th the mass.
You're still looking at billions of trips by millions of ships over thousands of years, such is the nature of terraforming, but 40 times less than taking the atmosphere away in those same ships.
And you can mine hydrogen from lots of sources in the solar system. Low gravity sources. That's a big deal. Pulling ice off comets in the outer solar system to get your hydrogen is much easier than lifting all that atmosphere out of Venus's deep gravity well. Even though you've got to take it so much further.
### How it works
The Bosh Reaction makes use of an iron (or nickle or [cobolt](https://en.wikipedia.org/wiki/Cobalt) or [Ruthenium](https://en.wikipedia.org/wiki/Ruthenium)) catalyst, so you might be dropping canisters from orbit which vent hydrogen through a screen made of your catalyst material. The Bosh Reaction requires high temperatures, but guess what temperature Venus is? Reaction temperatures are in the range of 450-600°C, and the surface of Venus is right in that range.
After most of the carbon dioxide is gone, the atmosphere of Venus will actually be bigger and hotter than ever before. You wont have an ocean yet, just an atmosphere made of steam. The Bosh Reaction gives a net gain of heat, and the resulting water vapor will be double the volume of the CO2 it was made from. It probably wont cool down on its own because water vapor is a better green house gas than CO2. You'll need a huge orbital sun-shade. You were getting one anyway, right?
### Afterwards
It will take years for the planet to get cold enough for the rain to start falling. Then it'll rain for a few more years. Once the clouds have cleared, you'll hopefully have an atmosphere thin and cool enough that humans can walk around in space suits without being smashed or boiled. But, remember that was only the first step. The atmosphere will be made of nitrogen, residual CO2, Hydrogen, and Methane. As well as all those sulfur compounds which where there in the first place. You also need to figure out what to do with all that carbon on the ground. This is just the beginning.
[Answer]
**CAPTURE AN ASTEROID**
**First we need an Asteroid:** Something with a lot of mass, possibly Ceres or Vesta although we could use just about anything with enough mass, like one of the smaller moons of Jupiter, Saturn or Uranus. We place the orbit around Venus. We make the peri-venusian point REALLY close to Venus's atmosphere. Enough so it pulls off a small but significant amount each time it orbits. And if we did our math right, it's going to orbit around Venus for a very long time. This solves our atmosphere problem, albeit very slowly.
**We need to strip off more atmosphere:** But we probably don't want this to take millennia so let's do something more to speed up the process, plus we're eventually going to need to do station-keeping to make it STOP pulling atmosphere off of Venus. We build mirrors. Big mirrors. And we aim them at our planetoid and vaporize the rock. Near the surface (in fact, we could put them ON the surface) we place positively charged plates. These plates will cause the super-heated rock to vapor deposit onto our plates. If we place them right, with the right charge, we can even pull nearly pure iron off onto it's own plates. Other materials would require some other type of purification, perhaps something close to a refinery by placing plates near the fractionation points of different materials similar to an oil refinery. We do this for two reasons. First, we're greedy and want the raw materials. Second, because if we change the distribution of mass in our planetoid, it will change it's orbit without the need for reaction mass.
**We need to reduce solar radiation:** Now that we have a huge supply of raw materials for nearly free, we're going to build a series of solar panels and place them into the first Lagrange point between Venus and the Sun (and if that's too far away, as it most likely is, we'll put them into a Venus-synchronous orbit around Venus where they stand between Venus and the sun). We're going to put LOTS there. Enough to change the albedo of Venus and reduce it's surface temperature as well as block a significant amount of incoming radiation.
**We need to remove the poison out of the atmosphere:** Once the surface temperature cools, the active leeching of poisonous materials from pressure and heat on the surface will begin to lessen and then stop. This means the rocks will re-bind most of the poisons in the atmosphere back into the geology for us.
**We can speed up the removal of the atmosphere:** Also, by using our large laser array, we can ionize the atmosphere, further bleeding it off into space.
[Answer]
Exporting the carbon dioxide from the Venusian atmosphere is not the most effective way of terraforming the planet. It isn't realistic. This answer offers an alternative.
Fortunately, if you have this level of space technology there are better options. What you need to do is a three step process.
First, convert atmospheric CO2 into carbonate rocks. Most of Earth's CO2 is locked up in the form of carbonate rocks. To do this, just add water, Actually a ginormous amount of water. Fortunately, the solar system is chock-a-block with astronomical bodies full of water. Europa, Ganymede, Enceladus, and, possibly, even the dwarf planet Pluto. Instead of using Drainage ships to capture the Venusian atmosphere, use similar sized interplanetary vessels to import the equivalent of the Earth's oceans from Europa, Ganymede and etc. Dump the water in Venus' atmosphere and allow geochemistry to take its course. Thus, converting atmospheric CO2 into carbonate rocks.
Secondly, build a system of solettes as discussed in AndyD273's answer, to block out excess insolation (basically, sunlight) and allow the planet to cool down to acceptable temperatures. Once human settlers are living on an eventually habitable Venus this can be modulated down to Earthlike levels of solar radiation.
Thirdly, introduce photosynthetic organisms into the Venusian oceans and seas. These will convert the remaining CO2 into an oxygenated atmosphere. The original proposal by Carl Sagan, using algae, is now regarded as dubious science. However, a technological civilization capable of terraforming Venus will have more advanced biotechnology and will be capable of producing suitable organisms to do the job.
While the three-step process of terraforming is scientifically plausible, it should come with the following product warning.
**Terraforming planets to human levels of habitability will usually geologically long periods of time.**
This does mean millions of years. It's really a problem of scale. Easy to overlook the amount of change required on a planetary scale to terraform a planet. Don't be in a hurry to pack your bags for a move to Venus in the near future.
[Answer]
The mass of the atmosphere of Venus is [round-about 4.8E20 kg](https://en.wikipedia.org/wiki/Atmosphere_of_Venus). The largest ship ever built is the [Seawise Giant](https://en.wikipedia.org/wiki/Seawise_Giant) at 657,019,000 kg. It would require just 700 billion trips, assuming it could be made to get from here-to-there with cargo at the density of oil. And completely neglecting what it will use for fuel and reaction mass. I would say that's not feasible unless you invent some crackling new forms of space travel.
If you just want to get the gas off of Venus and don't mind ejecting it into space, you could build structures that ionized the atmosphere and jetted into interstellar space. You could make these things solar powered. Escape velocity from the neighborhood of Venus to interstellar is something-like 50 km/s, plus the 10 km/s to get away from Venus's gravity, so a total of 60 km/s. That's probably do-able.
You would need some HONKING big accelerators. Venus has an area of 460 million sq km. So if you could build 1000 accelerators that were each 1 sq km in area, and pumped a full column of air out in 100 seconds, it would require 540 years of operation to get rid of the required atmosphere. You might need to use most of the area of Venus to get enough energy from solar collectors.
So, no, I would not call that feasible either.
[Answer]
The only realistic way of making Venus more habitable is to add some microbes that can transform carbon dioxide to carbon and oxygen in solid or liquid form and to gaseous oxygen, in a process similar to photosynthesis. The microbes will have to live approximately 5 km up in the atmosphere, where temperature and pressure is similar to what it is on the Earth's surface. The produced oxygen has to combine with hydrogen, from the solar wind, to form water, maybe catalyzed in the microbes. Organic compounds will snow or rain down on the surface. The atmosphere will thus decrease in volume and the surface temperature will drop due to lower pressure at the surface. At some point the temperature will drop enough to make the water vapor condense and liquid water on the surface will be present for life.
The biggest problems seems initially to be shortage of water and shortage of hydrogen. This will make the process take long time.
A similar process once took place on Earth and it lasted hundreds of millions of years.
The [Outer Space Treaty from 1967](https://en.wikipedia.org/wiki/Outer_Space_Treaty) is an international agreements against migrating life to other planets. This agreement first needs to be abandoned, or the space vessel could be sent up from a non participatory state.
Sending a capsule with such bacteria to Venus is not a demanding task. A small group of people can do it.
[Answer]
## Laser Death Ray Terraforming
* build huge solar powered lasers close to the sun
* tune them to a UV-wavelength (for laser range), which CO2 absorbs almost completely
* blast Venus for a few years until the atmospere looks acceptable
This means that you attempt to get rid of as much CO2 as you can without loosing too much N2. If the rate of N2 loss is only ten percent of that of CO2 loss, only 0.3 atm N2 are lost while the CO2 has been removed almost completely. It might be possible to ionise the escaping CO2 in order to capture it with an electromagnetic tether megastructure around Venus.
* import hydrogen gas from the outer solar system to produce water
* cover everything but the poles in reflective foil
* colonise the poles with buildings on stalks
* wait until the planet cools
Not really the most economic way to terraform Venus, but one of the quickest. This could probably be done within a decade with some lunar or mercurian industry. Also, the 3 bar nitrogen atmosphere and the resulting light nitrogen narcosis is a feature, not a bug.
[Answer]
How about using funnel in the atmosphere leaked to outer space. Wouldn't that drain the poisonous atmosphere? Space is the ultimate vacuum ya?
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[Question]
[
This question is going to take some set-up to understand the world it is operating in. This is a modern-day magic world that I've been building up. Magic exists, is hidden, and is quite powerful.
**Concepts**
Physics still works normally...magic just has the ability to supplant the normal rules for a while. Living things possess some level of spell resistance, increased as they are more magically powerful...so altering the body of a living target is much harder than altering their environment. It is much easier to generate a magical effect close to the body, than to do so remotely (at least for the style of magic I'm talking about for this question)
Magical Limits: Everyone who can wield magic is constrained by two limits on their power. Burst Limit and Sum Limit. Burst Limit is the amount of magical energy that you can channel in a moment, determines how 'big' a spell is. Sum Limit is the total amount of magical energy you can channel prior to exhaustion. Exceeding these limits can cause Bad Things™ to happen to you. A spell can be sustained and added to once it has been cast, but this isn't used by most magic users.
Function of spells: Magic is controlled entirely in the mind. However, controlling magic is *hard* and so most magic users will use words, gestures, prayer slips, etc as a form of classical conditioning to make it easier. For example, if every time you sling a fireball, you say "Eldur" (Icelandic for Fire), then eventually you will condition yourself to mentally control magic into a fireball when you say "Eldur." Crafting a spell on the fly is possible, but requires a lot of concentration.
**The Character**
Mark is a well trained Magus, but his burst limit is simply pathetic. His sum limit, however, is enormous. So, to simplify that a bit...he can produce magical energy at a slow, steady, nearly endless trickle. While this is pretty good for Enchanting or sustaining magics, it's pretty terrible at straight combat. His low burst limit means that if he tried to just fling a fireball on the spur of the moment, he might be able to make your hair curl a bit with a burst of heat. Mark is also currently a student at a normal university, studying the sciences, looking for ways to work around his magical issues.
**An Example of a combat spell, as produced by Mark**
Mark uses his magic to begin gathering a static charge in the air around himself, keeping himself insulated from it. Once he has gathered enough electricity, he sends as much of an electrical shock towards his target as he can, and releases his hold on the gathered electricity. The rest of the electrical charge follows the path of ionized air created by the small jolt, resulting in what is effectively a lightning strike. This process takes about 60 seconds for a moderately powerful jolt (think stun gun)
**The Question**
Mark needs a way to abruptly knock an opponent to the ground and keep them there without touching them. He is not aiming to kill, and is at fairly close range (so no creating a small bit of antimatter or anything). Using his understanding of the sciences, and the slow trickle of his magic, is there a way he can pull this off? It's okay if he needs some prep time before the spell goes off, as long as you can't tell he's prepping it by looking at him or being in the same room as him.
The situation in which he would throwing this spell down would be an urban environment, somewhere indoors.
[Answer]
You could separate out the oxygen from around them, causing them to pass out.
Basically, Mark would be operating as [Maxwell's Demon](http://en.wikipedia.org/wiki/Maxwell%27s_demon) with a one-directional selective membrane - allow atoms to move away from the victim, but not toward. You wouldn't even need to select for oxygen - you'd basically be creating a localized vacuum. Eventually, the person would just collapse for no apparent reason.
Once they're on the ground, you can let the air flow normally if you don't want them to suffocate - it takes a while to reach full capacity after something like this.
SCIENCE, B!TC#E$!!!
### Addendum:
If you want to go REALLY abrupt, you could freeze the moisture in the air column directly above them and make it fall, burying them suddenly under a sheet of snow and ice.
[Answer]
This isn't won't "pin" the enemy, but is likely as effective: screw with their equilibrium.
By inducing tiny bits of force/movement in the right place, you can trick the enemy into thinking that they're moving/falling. This will cause reflex movement to counteract the perceived movement, dizziness, and possible vomiting.
And best of all, the bits of the inner ear that handle this stuff are tiny. You shouldn't need much magic at all to manipulate them.
[Answer]
Since Mark doesn't seem to be too effective on the offensive front, I'd suggest something subtle. Animate some rope and have it wind around the target's legs (to restrict movement and cause a fall) and wrists (to prevent easy escape), then have the rope tie itself into a knot. Alternatively, you could use manacles, zip ties, handcuffs, or even the almighty duct tape.
Although, duct tape may be too magical to be considered science...
[Answer]
Chloroform! All the mage has to do is float a drop into or in front of his adversary's nose. Boom. Incapacitated.
Chloroform, however, is pretty lethal. Traditionally you soak a rag in chloroform. If you left the rag on the person's face for an extra couple of seconds after he passed out, he'd likely die. So that's a concern.
[Answer]
He could fuse the opponents feet to the ground by, making the ground sticky or somehow stitching their shoes to the ground and then startle them by throwing some harmless but aggressive looking magic at their face. They would instinctively try to step backwards and fall. Its very difficult to get up with your feet glued to the ground, but for good measure he could make the ground behind the opponent sticky as well, keeping them on the ground.
[Answer]
Mark is going to have to become a really precise Mage to make it work well for combat magics.
Riffing on the slippery angle, just make the soles of their shoes Ultra slick or friction-less. It affects a very small area so should not have a lot of energy requirements. That could be his go-to for surprise situations since it would incapacitate his opponent momentarily in order to use his wizards staff in it's secondary capacity as a big heavy stick.
I was slightly unclear about Magical resistance in people but if affecting certain parts of the body is ok, then making skin slippery is an additional thing. Direct action against other parts of the body might be to stimulate pain centers in the brain, or stimulating pain in joints, hands, etc. Mark could also turn his opponents eye lenses opaque temporarily.
If direct action on the body is forbidden then launching small, sharp projectiles at the eyes and face would be an effective way to harm an opponent with minimal burst energy. He could also possibly use incredible shrinking clothes to bind his opponent up making movement difficult. Using a necklace the opponent was already wearing to choke, a bracelet to squeeze a wrist making hand movement more difficult and grip unsure. Small actions that would be easy for someone like Mark to pull off.
The point is very small actions aimed at critical points in the body are how he could be effective even without big burst power. It's the sort of thing that makes martial arts like Wing Chun effective against larger opponents.
[Answer]
Minimum effort.
Trigger a momentary sodium imbalance in the target's Tibial nerve. This causes a calf spasm, making target fall. (if not allowed affect inside of target's body or incapable of the required precision, an externally applied static charge over the nerve behind the knee can have the same effect)
As target falls, coat a few cm2 surface below with very thin layer of cyanoacrylate (superglue).
That's all folks.
Subject is down on the ground, uninjured unless the fall itself did damage, and is glued to the ground.
Total effort required: one chemical or electrical precise pulse of less than 5 joules.
One alteration/conjuring of about 1/15th cm3 of a simple chemical.
[Answer]
Well I would think that if he can generate a high voltage shock for as long as he needs (low power) that he could have his own 'taser' spell that would keep someone down until he let them go, but be careful because holding the 'trigger' to long can cause someone to suffocate
[Answer]
If science works, any form of energy storage is on the cards. Kinetic (flywheel?), electrical (capacitor?), pressure vessel, chemical (battery), thermal, etc.. And then add any projectile you like.
For bonus points, projectiles could be ice frozen from the air.
[Answer]
If Mark is able to create a containment for electricity, he could possibly create a containment, then slowly increase the gravity within that containment. After it reaches a reasonable point, move the containment area over his target and they will not be able to stand as long as he maintains it.
[Answer]
What about making the ground under their feet super-slick? Here's a product that is super slick...
<http://www.insidescience.org/content/slip-sliding-away/2281>
Here's another article on frictionless surfaces...
<http://science.howstuffworks.com/10-uses-for-frictionless-surfaces.htm>
There are plenty of other ways to make a surface slick as well.
[Answer]
Considering that low Burst, high Sum seems to be effectively aimed at sustainable magic. Use magic to increase his personal speed, reactions, and strength by enough to evade any counterattacks and pursue close combat where you can keep the other person or Magus off balance and unable to cast.
Pros:
* Fast
* efficient
* unexpected (you probably wouldn't expect a Magus to use martial arts)
Cons:
* Must be close range
* Higher chance of harm to you and your target
whoops, Criteria is to not touch them. Making this point moot. However, this is probably his best combat option. He can bulk himself up and use magic to push slightly further.
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[Question]
[
I'm finally actually participating in the weekly topic challenges, instead of just helping run them.
Let's say that there's a siege around a small series of fortifications that comprise the only defense of a small band of rebel soldiers (the technology level is about that of Europe circa 1100). The surrounding army can't seem to get in because the rebels have chosen to hide amidst old fortifications, like the ones at some places along [Hadrian's Wall](https://en.wikipedia.org/wiki/Hadrian's_Wall). They're old even at this point in time, but instead of some of the fortifications at present-day Hadrian's Wall, the fortifications are ten feet tall and about two feet deep.
The soldiers have no weapons that they can use to get in. They can't go over the wall, because there's a two-foot deep ditch surrounding the wall that increases the effective height to about twelve feet. They have no rope, and only bows and arrows, swords and shields. There are no trees of other vegetation which could help them - in fact, no natural materials they could use at all. Yet they need to quickly squelch out the rebels (i.e. within a couple days, at which point they have to leave and fight elsewhere), who have enough provisions to survive for two weeks.
Fortunately, the soldiers know that the surrounding countryside is filled with a certain kind of insect that can eat through stone. They spend all but one of their remaining days catching enough of these insects. They gather them in bags and then let them loose at the base of one of the sections, where the insects manage to carve a hole big enough for an armored man to get through. The rest is history.1
Could these insects exist? If so, would it be reasonable for a large swarm (e.g. 5,000 - the soldiers were busy) to eat a hole of this size in a period of 24 hours?
The surrounding region looks a fair bit like Northeast England, as shown here:
[](https://upload.wikimedia.org/wikipedia/commons/e/e7/Hadrianswall2007.jpg)
Beautiful, isn't it?
---
1 Not yet, actually. I don't know what happens next.
[Answer]
It seems more likely that they could be used to weaken the wall, to the point where you could take it out with primitive siege equipment.
For example, imagine a hyper-active ant or termite species that builds large underground nests. You could sneak those into the area outside the wall. Over a few days, they'll excavate underneath, weakening the wall's foundation - at that point you can knock it over easily, or finish the excavation manually and cause the wall to tumble down.
[Answer]
If those insects indeed exist and are common on the region, castle builders would be a *tad* smarter.
If there was such an insect that could burrow in stone, they would be a pest to the walls. Castle Builders would have already adapted, and probably created some type of coating to prevent those pesky bugs from making nests on the buildings, especially if they are common as you say. Also, you have the problem of coordinating those insects. Why do they dig into the stone? They want to make a nest? If so, they wouldn't eat all the way to the other side. They use the stone as food? Improbable, since stone is not exactly the most nutritive food out there [citation needed]. Would they dig together to make a huge tunnel? certainly not - digging a tunnel big enough that you would be able to fit inside is something that animals do to create some protection, not to breach wall. Your insects, if they were able to dig stone, would be mostly interested in creating several small nests than one big, huge tunnel.
There is the digging mechanism issue, too. For they to dig solid rock, they would need a really complicated mechanism of acid-production. The queratin-based limbs of insects is not hard enough to damage rock, and if your insects had some kind of adaptation to make them stronger, it certainly would be a slow process. Think about how long a human, using modern tools, take to create such a hole in a thick stone wall.
If they produced some type of acid, they would be able to produce just minute quantities of it each time, and would need food and rest between 'discharges'.
Another issue would be hunting those insects. If they can create nests in solid rock, how would your hunters gather them in the first place? The nests would be highly inaccessible without specialized tools - tools that an army would probably *not* carry with it.
[Answer]
I can find historic references to insects used in siege warfare but only as projectiles. Having a hive land on your house will ruin your day. There are burrowing insects but they prefer the softer mud and mostly just to build shallow nests.
Leaving history behind, is it possible? Difficult to say. To make it believable what you really need is a story of what good this does the insect. Pill bugs dig under stones because it's a very effective way to hide from predators. What advantage would they have if they could dig directly into the stone? Hide from predators that turn over stones?
Another problem is even if you had a swarm of millions when they were turned loose on the wall they'd each make their own little hole. Even if they all dug completely to the other side, for some reason, what you're left with is a stone wall that is still standing. Just with a number of tiny holes in it.
When the number of holes is dense enough the problem will be that the lazy insects would just use the existing holes to get to the other side and not make any new ones.
So either your insects have to be as big as an armored man or you need the wall made out of something the insects like to eat.
[Answer]
How important is it that the attackers introduce the bugs?
What I mean is, if you happen to figure out some kind of bug that could eat stone, does it have to be introduced to the wall by the attacking army? This is a bug that nests in stone, and here are some walls that have been around for a really really long time, and it's above ground so the bugs don't have to mine for it. Why would these bugs not have already found and weakened the wall. So your attacking army is laying siege, trying to figure out how to get in, and one of them notices bug sign, like how termites will build tunnels up walls to get to wood without being exposed to the sun. So they know that section of wall will be weak, and can batter or dig at it.
As for how they exist, have a predator like an ant eater that is really good at digging up these bugs, but because of super hard and sharp appendages, these bugs working together are able to dig into softer stone given time and that gives them protection from the predator. An old wall would be extra attractive too because loose mortar would give them a way in that virgin rock wouldn't have, and by weakening the mortar they would severely weaken the wall.
[Answer]
[You want some form of modified termite.](http://en.wikipedia.org/wiki/Termite)
Now...this is still going to be a pain. But here is what I am thinking.
**How:**
* These modified termites secrete an acid that softens certain inorganic minerals for consumption/extraction. Termites generally stick to fibrous/cellulose materials but they will eat gypsum too which isn't stone but isn't wood either.
* It would probably be more believable if the stone in question was a bit softer/more porous. Granite would be tough to accept (though granite is pretty porous).
**Why** (options):
* The mineral is needed for nutrition and is only available in trace amounts outside the stone.
* The stone matter is needed to construct their termite forts.
* Some termites have 'farms' in their mounds, perhaps they use limestone as a fertilizer.
**Problems:**
* The rate you are asking for (24 hours) is going to be a stretch. You would have to have way more than 5000. A termite mound in Africa can house MILLIONS of termites.
* Completely bringing the wall down or eating only a section seems impractical as well, they will spread out to consume. But perhaps they make the wall soft enough that men with war hammers can break a hole in it easy enough.
Course you could just introduce a super termite that is a major plague on the place...but if they consume that quickly why would anyone ever build anything out of stone.
[Answer]
**The insects are explosive.**
The miner beetles your soldiers are out gathering don't actually eat through stone walls, per se. While they build their nests in stone by secreting small amounts of explosive chemicals to blast off small flakes of rock, expecting them to burrow through a wall would be silly. If left to their own devices, the insects would spread out and build lots of shallow nests in the surface of the wall, instead of all burrowing in one spot, if they even decided to build nests there at all. They prefer loose, fractured stone for their nests, as construction is easier there, which is why the wall hasn't been slowly blown to dust by their nest building habits over the course of the time it's been standing.
However, these insects possess a powerful defensive mechanism. Their stone cutting abilities come from chemicals they produce and stone in a pair of membranous sacs which explode when combined. When the beetles are killed, these sacs rupture, creating a powerful localized explosion strong enough to *highly* discourage any animals from trying to eat them.
What the soldiers have done is gather thousands of these normally solitary creatures and stuffed them in a sack. They don't intend for the beetles to leave the sack and eat through the fortifications. They expect them to die. After being placed next to the wall, a single arrow into the sack of beetles will kill a few, triggering a chain reaction and an explosion powerful enough to blow through the wall. While a single, soldier-sized hole slowly bored through the wall would be easily defensible, the resulting explosion will create a large hole as well as killing or injuring any nearby guards with shards of rock blown loose by the blast.
The rest as they say, will be history as soon as someone gets around to writing it.
[Answer]
If the wall was made from limestone, and the insects stored quantities of acid (such as formic acid made by ants), then it might be possible to damage the wall slightly - i.e. take the surface layer off it - by throwing the insects at it so that they died and their acid was plastered on the wall.
However, to actually burrow right through the wall would likely take more ants (or whatever) than would be practical. You'd have only slightly more success by extracting the stomach acid from your soldiers, but to dissolve a man-sized hole through a wall even with that amount of acid would be unlikely to be possible, and it would likely take more time than you have. You'd have trouble keeping the acid where it was needed, and you'd have to keep replacing the spent acid with fresh.
There may be insects that generate acid, but that's an awful lot of acid they would need to generate. Acid has to come from somewhere, and that takes energy, which insects probably won't have in the timeframe you mention, unless there are literally tons of the bugs.
[Answer]
I can see a single option. Suppose your world supports to basic forms of life: silicon-based and carbon-based. Furthermore, the carbon-based plants are outcompeting or have outcompeted the silicon-based plants. Now a species with a similar place in the silicon ecology as termites have in the carbon-ecology could have evolved to eat silicon-rich stone. This would imply that your fortress is built with silicon-rich rocks. You would still need a very large amount of them as they won't eat in the direction you want them to eat. They'll probably follow the silicon-rich parts of the stone and hollow the wall in a way similar to wood-bores. Furthermore, they can only eat so fast, so you might need to adjust your timescales somewhat. Lastly, as we have developed various treatments against wood-bores, people in your world might have developed treatments against stone-bores (like drenching the stone in silicon-based poison).
[Answer]
I think the best bet is an acid producing silica-based life form like the Horta in Star Trek: The Original Series. The creature was ruining the mining colony and had McCoy say, "Damn it! I'm a physician not a bricklayer!" when he was called upon to help it. Hortas were big but a smaller life form might be feasible.
I think the main objection - already made - is that if there were such insects native to the area they would already have gone for the castle. Perhaps your invading army carry a colony with them in specially treated barrels or such.
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I recently wrote a silly little flash fiction piece in which some party-goers go hide in a bunker under an apartment building in NYC because of a "megablizzard." In said silly flash fiction, I buried the Empire State Building up to its roof in snow in about two weeks. (In my imagination most of the North East is buried almost this high in snow, but not the far south of North America.) Now I'm curious if this is in anyway possible.
My questions are, in a world where snowstorms are gigantic and out of control and the winter never ends or goes above freezing, would this be feasible? Could NYC get so much snow that the Empire State was buried (to the roof: 381 m, not the tip)? How much snow would have to fall in what space of time to bury the Empire State Building to the top? And if so, what would happen to surrounding city? (I mean physically. Obviously everyone would be trapped. There'd be major panic. Transportation would cease. But would buildings be crushed and such?)
[Answer]
That is a lot of [dang] water you've put into the atmosphere to be snowed down. (3125gal / square foot)
Worldwide, there's about 1/2" in the air at any one time.
Granted, if you've got time, you can pump more water out of the oceans, into the atmosphere and then snow it down. But typically large snowfalls happen in small locales (thus concentrating that average of 1/2" into much bigger heights), and not 'most of N.America'
That said, maybe N.America is getting hit hard, but NYC is getting hit *harder*.
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Crushing: More average snow may weigh 15 pounds per cubic foot and drifted compacted snow may weigh 20 pounds or more.
1250' == 25,000 lbs of snow at the bottom (well, minus a bit if the top isn't compressed, but after the first 10 feet, I'd assume that 150lbs will compress the remainder of the snow).
That'll definitely blow in the doors and windows.
Turns into 173 psi. So not enough to damage cement at the bottom (3000-6000 psi needed). Probably not enough to completely crush your cars either (but probably cave in the roofs, etc).
[Answer]
No, it is far from possible without human intervention or cheating.
It is not possible to have enough precipitations. In a year, Mawsynram (India) receive about 12m of rain. It could go to maybe 20m on a catastrophic year. That's still very far from the roof of the Empire state building. Let's also add that this is a subtropical climate affected by a strong monsoon. New York is much colder and cold air cannot contain as much water as hot air.
For snow, some on the snowiest places on Earth are located in mid latitude climates like New York. At these latitude, mountains receive a bit more but near sea level the maximum is about 1 or 2 m yearly. Some of the snowiest places are located in Tohoku, Japan. They receive a lot of snow because they are surrounded by water and the temperature are just below freezing.
**Is it really impossible?** Supposing the winter would never end and that the temperature of the ocean and overland stays about the same. With a succession of cold and hot air masses, each cold front would bring some snow.
New York receive (according to Wikipedia), 23,4cm of snow in the snowiest month of the year. Supposing we could maintain the same conditions indefinitely, I guess we could bury the city. If my calculation is right, at this rate, it would take 135 years to bury it. By that time, the survivors will be long dead. With this estimation, I haven't even taken into account that the snow would be compacted.
[Answer]
## Would this be feasible?
The highest *annual* snowfall in Central Park was about 75 inches (in 1995-96). During this year, 26 inches fell during the month of January. That is about a whopping 1/580th of the height of the Empire State Building.
## What would happen to the surrounding city?
**It would be crushed.** The density of snow is about 30% that of water when compacted (it would likely be much more because of all the snow above it). That is 300 kilograms per cubic meter. That is 114,300 kilograms of snow above *every square meter* of New York.
References:
>
> <http://en.wikipedia.org/wiki/Snow>
> <http://www.weather.gov/media/okx/Climate/CentralPark/monthlyseasonalsnowfall.pdf>
>
>
>
[Answer]
It would be termed "glacier" rather than snowfall. That much snow fell in how short of a time? Two weeks? It is not feasible in the least unless 10 years of very harsh and continuous winter did so; most likely longer. Google images of glaciers and take note of how thick they are. That building is about a mile tall and some of those glaciers can come close in thickness. Cars would be useless if snow ever got that deep. Glaciers move like slow rivers but are solid ice; TESB would be carried out to sea along with every building in it's path. Picture years of icebergs calving at the feet of TSOL.
It is as comical as ice age/climate change due to global warming; and would be a great movie.
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**Closed**. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers.
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**For context:** this is a very far future sci-fi setting, dozens of millenia from now, where dyson swarms and interstellar travel are commonplace, bioengineering and tech are so advanced they merge together and planets are by many considered obsolete as a living space. I'm however still trying to keep it somewhat grounded in known physics, there's no FTL and true magic-like clarketech is appearing only as secret supertechnologies or artifacts, if ever.
All in all, the topic of this question is deffinitely not the most unhinged technology in the setting and I could easily handwave it in, but I still want to get an idea of how ridiculous it is exactly to be able to give it a fitting place.
**Question:**
the thing I call iron drive is an idea for a spaceship engine which would somehow make its hydrogen fuel go through a rapid chain of fusion all the way to iron, like the lifecycle of a large star but much smaller and faster.
**Could something like this be even remotely possible? If yes, try to rank it from 1 to 10:**
* **1 = something we know how to do on paper**
* **10 = something which one could still call scientific and not blatantly lie**
**And add what you expect the thing to actually do and look like and why you gave it the rank you gave it.**
[Answer]
Can we fuse hydrogen all the way to iron at your tech level? Sure, why not? If stars can do it so can we.
Would we use it for propulsion at your tech level? Probably not, no.
Why? Because the energy density of hydrogen is lousy compared to that of antimatter. If your civilisation has mastered subatomic physics to the point where they can fuse hydrogen to iron in a controlled reactor, then they surely also have the ability to make and store antimatter. Consequently they'd be far better off performing the fusion reaction in a stationary power plant, using the energy to generate antimatter, and then using the antimatter for propulsion.
On the other hand, antimatter is dangerous, and while your civilisation likely has a lot of practice in handling it safely there might be situations where a safer fuel like hydrogen is preferred, even if it comes at a big cost in specific impulse. So you might find your iron drive being used in those cases. However, in that case the issues in Monty Wild's answer come in to play - going all the way to iron likely requires a huge increase in complexity (and hence weight) for only a relatively small gain in efficiency, so it might be that you would only go to helium in this case, or maybe carbon or oxygen, even if you had the tech to go all the way to iron.
[Answer]
To [fuse hydrogen](https://en.wikipedia.org/wiki/Proton%E2%80%93proton_chain) (not deuterium or tritium) to helium alone is a slow process. Just getting a given proton to fuse with another to form a deuterium nucleus is said to take billions of years, which is why we impatient humans go to all the effort of finding deuterium and tritium to put into our fusion reactors, which are still not able to produce a net gain in energy at the time I write this.
To get atomic nuclei to fuse requires a very large amount of pressure and temperature (which are almost the same thing). This is achievable by either piling up a whole lot of hydrogen in one place and letting gravity do the work - which is called a star - or by using lasers and/or powerful magnetic fields to do the compression, which takes energy, and as of now, more energy than you get back from the reaction.
In order to fuse matter more quickly, you need *really* high temperatures and pressures. You can do this by piling up more matter in one place, basically by building a bigger star, or by putting more energy into your compression mechanism. The trouble with putting more energy into a compression mechanism is that to make a viable, net-energy-producing reactor, you need to get out more energy than you put in, which in the real world is proving very hard to do. The trouble with fusing hydrogen to Iron is that the [binding energy curve](https://en.wikipedia.org/wiki/Nuclear_binding_energy#Binding_energy_for_atoms) shows us that you get a lot of energy for fusing hydrogen to helium (~7 MeV), but only a little more for fusing Helium all the way up to Iron (~1.8
MeV). Can you get back enough energy from all these extra fusion steps to justify the extra power it takes to run these more powerful compression devices?
[](https://i.stack.imgur.com/Au2LZ.png)
Now, assuming that you *can* make a reactor that can apply pressure equivalent to that within a 130-250 solar mass star during a [pair-instability supernova](https://en.wikipedia.org/wiki/Pair-instability_supernova) without consuming more energy than is yielded, you can fairly quickly get all the way to Nickel-56, which will decay within a fairly short time to Cobalt-56 and then to Iron-56.
However, a pair-instability supernova effectively spreads the star's remaining mass out over a wide volume, blowing it apart completely and leaving no stellar remnant behind. This is not what we want to happen in a fusion reactor, unless it is intended to be a bomb.
If our fusion reactor is capable of remaining intact during this runaway fusion reaction, we may get an unwanted side-effect, [photodisintegration](https://en.wikipedia.org/wiki/Photodisintegration), which is an energy-absorbing process that can lead to inward pressures so outweighing the normal outward energy-producing processes that the reaction mass would collapse, leading to synthesis of atoms heavier than Iron, or even the production of a black hole.
Of course, producing uranium is only going to absorb around 1 MeV of the total energy production, but a black hole is the last thing that you want. Depending on its size, it may either begin ripping apart your reactor, or it may evaporate due to [Hawking radiation](https://en.wikipedia.org/wiki/Hawking_radiation), which emits a whole lot of energetic gamma rays.
Now, if we're trying to use a fusion reactor as a torch drive, we're trying to achieve the greatest net gain in energy possible. *If* the energy cost in matter confinement isn't so great that it completely consumes the relatively small gain in energy from fusing Helium to Iron, we're not likely to get a whole lot of extra energy... but we will be getting a pretty efficient thrust, given the high mass of the ejected reactants.
However, I believe that this 'Iron Drive' is Clarketech. The reactor would have to be huge in order to contain the necessary mass to produce and sustain the reaction, and realistically, it would be so heavy as to make for a poor spaceship. It would have low accelerations, and it would likely need some sort of [Bussard ramscoop](https://en.wikipedia.org/wiki/Bussard_ramjet) to keep it fuelled.
[Answer]
There's very little reason to fuse heavier elements in general, partially because it is technically much harder (you need higher pressures and higher temperatures even than the regular flavors of fusion) and the energy yield per fusion is lower (see Monty Wild's chart) and the losses are higher (eg. via [neutrino](https://en.wikipedia.org/wiki/Carbon-burning_process#Neutrino_losses) pair production) which means the yield per unit mass of fuel becomes even worse (because each fusion involves many more nucleons than hydrogen-fuelled reactions).
That's not to say that fusion of heavier elements than hydrogen or helium is completely useless, however.
Waaay back in the dark ages of 1975, Daniel Whitmire proposed what he called the Catalytic Ramjet. The paper is referenced online ([Relativistic spaceflight and the catalytic nuclear ramjet](https://www.sciencedirect.com/science/article/abs/pii/0094576575900636)) but I'm not aware of a legitimate source of the paper that's not behind a paywall. The basic principle is that the classic Bussard ramjet reaction, proton-proton fusion, is a complete nom-starter because it relies on the decay of a diproton to deuterium which is mediated by the weak nuclear force and very, *very* slow (this is one reason why hydrogen burning stars last a very long time on the main sequence, whereas helium burning ones do not).
Whitmire proposed using the [CNO cycle](https://en.wikipedia.org/wiki/CNO_cycle) fusion process found in some large stars, whereby single protons (as a Bussard ramjet might harvest from the interstellar medium) fuse with a carbon, nitrogen or oxygen atom building up heavier nuclei each time. The neat bit is that the heavy elements don't get "used up" as the final stage, $\ce{^1H + ^{15}N -> ^{12}C + ^4He}$ with the four protons absorbed in the process shooting off as an alpha particle for handy direct energy conversion or thrust and (in theory) the heavy carbon being retained for re-use. There are other proton-consuming cycles, such as [Neon-Sodium and Magnsium-Aluminum](https://www.researchgate.net/figure/The-NeNa-cycle-and-its-link-to-the-MgAl-cycle_fig1_304003211), but as those elements get heavier the reactions get more and more inconvenient and less rewarding.
Of course, Bussard ramjets are basically impractical in the real world... drag on the interstellar medium just makes life too difficult, and the solar system is in a bit of a thin area of the ISM anyway just to make things harder. Some of the engineering difficulties are covered in this presentation by A. A. Jackson: [The Interstellar Ramjet: Engineering Nightmare](http://www.aiaahouston.org/Horizons/Ramjet_IRG.pdf). If you had some way to work around some or more of these issues... ways to generate more intense magnetic fields, perhaps with monopoles, highly efficient UV lasers, amazing high temperature high power superconductors, super refractory materials, efficient gamma voltaics, who knows what else... you might be able to justify fusion spacecraft with reactions involving stuff heavier than boron. The monopoles are certainly quite magic and have their own serious implications on the physics in your world, but the other issues might be solvable without recourse to Clarke's third law.
Antimatter probably makes for better rocketry (with all its accompanying risks and inconvenience of course), but for interstellar flight using reaction engines is a losing proposition and you should be using beams instead.
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[Question]
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I am starting to work on an alternate-timeline story on Earth. Is there a web site or software that will let me see just the mountains, rivers, etc. without national or local borders, or cities and towns?
Thanks!
[Answer]
## What you're looking for is a "topography" map
[Topographic studies are the study of land shapes and forms](https://en.wikipedia.org/wiki/Topography). Since you want mountains, lakes, rivers, it looks like this kind of studies and maps are pretty spot-on.
Google map already does this kind of thing at a basic level, [Google Earth](https://earth.google.com/web/) being its more "advanced" brother.
[](https://i.stack.imgur.com/GNeJm.png)
Going further with more specialized maps, you have [topographic-map.com](https://en-gb.topographic-map.com/maps/iw56/The-World/), which provides pretty accurate reliefs of mountains in pretty and clear shades of red, green and blue.
[](https://i.stack.imgur.com/RIxPE.png)
And if you still don't have enough, you can find more on Wikipedia. If not, then in [wikimedia commons](https://commons.wikimedia.org/wiki/Main_Page). Here, for instance, [Argentina's](https://commons.wikimedia.org/wiki/File:Argentinien_topo.jpg)
[](https://i.stack.imgur.com/02Ezp.png)
If this is still not enough (why'd you want so many maps, anyway :p?), you can find in some bookstores atlases which almost always go over this kind of map. Finally, some countries hold topographic studies themselves, held on some government websites. It's of course highly dependent on said country's budget in geography, but you might obtain even more accurate data, or perhaps historical ones.
[Answer]
Google maps will work.
[](https://i.stack.imgur.com/F7P5P.jpg)
Here is Washington DC and Delaware. Go to the place you want on Google maps. Go to Layers on the bottom left. CLick on satellite image. When you do a button called "labels" will no longer be grayed out. I put a red arrow on that button. Uncheck that and labels will go away as in the above image. Presto!
[Answer]
**I've got your map right here!**
Check out the [Equal Earth Physical Wall Map](http://equal-earth.com/physical/), a high-resolution non-political map (exactly what you're looking for) that can be downloaded in high resolution *for free.* This gives you the entire globe to lay out on your table or computer screen just as big and detailed as you want it to mark up, design, and build your world as you see fit!
[](https://i.stack.imgur.com/KuOFf.png)
*Can we say, "Gamma World" anyone?*
You have different kinds of world maps you can download (the biggest one is quite large) and I've linked you to their download page.
**Important!**
My only complaint with them is that rather than creating a PDF for their vector version, they created (of all things) an Apple MaxOSX Adobe Illustrator CC version. Smart people, right up until they created the most potentially useful version of the file, then they tripped.
Nevertheless, take a look around at what they have. I think they're cool.
[Answer]
All answers currently give solutions that show cities (e.g. satellite imagery), whilst the question explicitly asks for a solution that does not show cities.
>
> Is there a web site or software that will let me see just the mountains, rivers, etc. without national or local borders, ***or cities and towns***?
>
>
>
Google Maps allows configuring custom map Styles that allow customizing the look of the map. By hiding all labels, road and human-made landscape we get I think exactly the map you want:
[](https://i.stack.imgur.com/hc6eJ.png)
(Important: This image is NOT licensed under CC! It's a screenshot from Google Maps)
# Step 1: Google Map Style generator
Go to <https://mapstyle.withgoogle.com/>
# Step 2: Set the main category slides to hidden
[](https://i.stack.imgur.com/wqeH7.png)
(Important: This image is NOT licensed under CC! It's a screenshot from Google Maps)
# Step 3: Hide human-made landscape
Select "More options" then "Human-made" then "All" and then "Hidden"
[](https://i.stack.imgur.com/VczMl.png)
(Important: This image is NOT licensed under CC! It's a screenshot from Google Map Style)
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[Question]
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Exactly what it says on the tin: what would an above-ground residential apartment designed to negate the effects of a one-kiloton nuclear surface burst at 500 meters look like?
[NUKEMAP-2](https://nuclearsecrecy.com/nukemap/#) says that the effects of a 1-kiloton surface burst at 500 meters are:
* an overpressure wave of approximately 4.2 PSI
* thermal radiation of approximately 29.3 joules per square centimeter
* ionizing radiation of approximately 5050 rem
In addition, take into account the fallout produced by such an event: at 500 meters, that's somewhere between 1 and 1000 rads per hour, depending on the wind.
By "functionally negate", I mean that when the detonation occurs, the occupants of the building may or may not (presumably, they will) notice but will be functionally safe from ionizing radiation (I know some small measure of it will get through no matter how much shielding there is), as well as unharmed by any blast/thermal effects, as well as safe from the maximum-possible 1000 rads/hour of fallout for approximately a week.
By "above-ground", I mean that, aside from a single basement level, the structure is above the ground.
The building has 150 apartments in it.
What would an apartment building, built to withstand this look like? Preferably, it's skyscraper-style, but I can understand how that might make nuclear defense difficult.
[Answer]
You are looking at a piece of real estate that was specifically built with the *expectation* of taking a hit, the building is simply too expensive to justify if you don't have a reasonable expectation of it being nuked, and has several rather odd and expensive extra features that you'd never bother with (mainly because of the fallout not the blast):
* It will look like a piece of [brutalist architecture](https://en.wikipedia.org/wiki/Brutalist_architecture) somewhat akin to the lower portion of the Torre Velasca in Milan shown below, with a heavy concrete facade broken by minimal, deepset windows, the panes will be thick, lead doped, antiradiation glass with inbuilt wire mesh to reinforce them against blast pressure. I include external windows on the assumption that the building code is either outdated or utterly stupid and requires them. They do have aesthetic benefits and not having to light the storage corridor is a saving but the building would be more secure without.
[](https://i.stack.imgur.com/xbEcu.jpg)
* There will be only one ground floor entrance with heavy but narrow front doors and an anteroom that blocks direct movement paths to dissipate blast pressure in the event that they are open. The whole front lobby area of the building can be isolated by internal blast doors in case of excessive contamination and alternate through the building used instead.
* The walls will be built with more reinforcement than is strictly necessary and will incorporate a Lead baffle layer to prevent radiation penetration. There will be a sacrificial thickness built in to the outer structural elements of the building that can [spall](https://en.wikipedia.org/wiki/Spall#Spalling_in_refractory_concrete) off when exposed to the thermal shock without compromising building strength.
* The building will need blast shutters and a closed circuit ventilation system, not to deal with the initial blast, although the shutters will be handy if they can close fast enough, but to keep the fallout at bay.
* Internally people will not live/work exposed to the windows/external wall of the building, a corridor will separate the outer skin of the building from the lived-in spaces with a solid internal wall, this corridor is purely a maintenance/storage space. Primary access into the living spaces will be through a central elevator and stairwell shaft core. The outer walls may become radiation saturated over time is this air gap is useful regardless of whether there are windows in the outer wall or not.
* The building will be as short as possible and will not expose any vital functions on it's roof space. The ceilings will be low, 2.5m(~8ft) or less, to keep the floors as small as possible. The ventilators, water tanks, etc... that would usually grace the roof line of an apartment building are either in the basement or concealed in a top floor engineering level under the protection of a heavy roof.
* External links are hardened and put as deep underground as possible. No satellite uplinks, all communications data will come in over hardlines, preferably fibre optic because it's less effected by radiation than metal wires are. The water pipes etc... will be buried deeply across the city and the service branches will come into basements from below the foundations of buildings so they provide the shielding that would otherwise be lessened by decreased depth.
Given that the building is being designed to take a hit it is probably being built to take more than 1kT, most strategic weapons are much larger. Again fallout is more of an issue than blast due to the persistence of those effects.
GrumpyYoungMan has noted that the ventilation system will need to supply the building on a completely closed circuit for at least 50 hours with heavy scrubber capacity for around 100 days. I would suggest that it will actually be rather larger per the fact that 1kT is a rather small blast. Further he has noted that the lead baffle is rather inefficient and that a water jacket would give as much protection from the initial blast and could then be pumped out, through builtin decontamination sprinklers, to lessen the ongoing effects of the post blast contamination and fallout on the building making Lead-lining unnecessary, I'm not 100% sold on this as I'm not sure how heavy the jacket would need to be, and thus the structural requirements, but it is an idea worth exploring.
[Answer]
**One-kiloton nuclear surface burst at 500 meters is not that bad**
From the blast wave perspective, it does not look as bad as a category 5 hurricane - and residential buildings in some municipalities, like Miami, are already built to withstand that. Of course if the charge detonates closer, or it is more powerful, then the situation would change, but if we strictly follow the requirements in question, then everything is good.
The light flash and ionizing radiation are more difficult to deal with. Granted, they are easy to deal with if the building has no windows - but this is residential building, so I assume that having windows without permanent shutters is an implied requirement.
Penetrating radiation can be dealt with by utilizing heavy metals in glass composition. It is also possible to filter out most of infrared light. Negating visible light flash is probably the most difficult task, and I am not sure we can get 100% secure protection here. There are "smart" dimming glasses, but I am not sure they can act fast enough to prevent eye damage if someone would be looking from the window straight into the nuclear fireball.
However, there is one good solution to the windows issues. If our building is designed as a courtyard, rather than a tower, the windows facing the courtyard will be safe. Granted, without usable windows on the outside inhabitants will miss the views, but at least we can have both safety and windowed apartments.
Radioactive fallout is also a manageable issue. We need to make sure that the building has central ventilation system that can be switched to adequate filtration, and people won't be able to open windows in their apartments.
[Answer]
An octagonal concrete wall will some decorations on it, but no windows. It may have some cameras to allow residents to look what is happening outside. The light for the apartments would come from the courtyard in the centre. If the ratio of the base size to the height is big enough the external perimeter wall won't have to be too thick. To reduce the sense of confinement the roof would have to be a well furnished terrace.
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[Question]
[
An alien ship that has been observing earth, and humans in particular, for the past year has sustained catastrophic damage and crash lands on earth. While the alien ship has a crew of about 20 specialists, the damage was significant enough that all are injured, with injuries ranging from minor to life-threatening, including some deaths. Enough control was maintained during the crash-landing that the aliens were able to choose the location of landing (the Boston Airport) and send off a broad S.O.S. to humans. Could the humans give the aliens medical attention in a manner that would save lives or limit future complications?
Additional information:
* Due to the incident and stresses of re-entry, all
electrical/information storage systems onboard the ship are
completely destroyed.
* All of the aliens are specialists in a field and are researching
some part of Earth, which means they have a college-level education
including knowledge of their own anatomy, BUT
The medical bay was located on the bottom of the ship, which
sustained the worst damage. The main doctor is dead, his two
assistants are in critical condition and unconscious. No one conscious has
studied medicine.
* Fortunately, the alien researching human language is conscious,
and can speak English passably. The translation work she has been
doing for other departments includes some for the medical staff,
giving her the equivalent human anatomy knowledge of a third
grader. She has broken bones.
* The aliens look
like a cross between a human and a giant bird. They have some
equivalent organs to birds/humans, but not all, and some functions
are performed differently.
* All injuries were directly caused by the crash, and all aliens
were healthy beforehand.
* This is presumed to happen present day.
* They are aliens are helped by human doctors/vets who follow
current medical ethical practices.
[Answer]
The ones with minor injuries will be easy to treat, as bandaging and other such basics should not be too different. Even if they were silicon based or such, but with some self-healing capacity, just straightening them into their normal shapes and taking care of external loss of liquids should be enough for them.
With one of them being able to communicate with the humans and able to explain food needs and a little bit about medical needs (some from the experiences of the conscious aliens the translator communicates with), food, liquids, energy needs and such should quickly be possible to fix and some more advanced treatments should be possible.
Some of the internal damages should also be possible to fix with some good guesses and by analysing (and testing procedures with) the dead aliens.
The worst issue might be infections with Earths diseases (bacteria, fungi, amoebae, larvae, mites, fleas, small worms...), and even some things humans don't see as such but aliens might not have immunity against - algae, larger worms, and many more.
I'd assume humans would quickly seal of the alien ship and create a sterile makeshift hospital right at the airport, but they might also move the aliens to the 'best' nearby clinic, with all its multi resistant germs, standard procedures (glucose infusions and such) which might be deadly for aliens, and other such issues.
There's also a question how much humans try to communicate with the aliens about their needs, or whether they are more interested in security issues, fast answers to where they come from, and so on. Whether security minded or science minded humans have the say. And so on.
[Answer]
**Absolutely not**
I know a lot about my own anatomy, and I could easily scream, "I'm allergic to Penicillin!" but I couldn't possibly explain to an alien doctor what Penicillin is ("it's moldy bread! What do you mean, 'what's bread?'") and your aliens couldn't possibly explain that to us, either.
Unless by a miracle of evolution their physiology allowed them to be 100% compatible with human pharmaceuticals, the two and only two things we could do that wouldn't run a massive risk of killing them is bandage their wounds and splint broken bones. And we'd need to do that without the use of X-rays because we have no idea how they would react to X-ray radiation. ("Okay, a quick scan and HOLY MOSES HE'S ON FIRE!")
Oh, we'd be running tests on blood and tissue samples like mad. In fact, whomever has those samples would be beating off every government agency and college or university with a stick! But tests take time to run, especially thorough "we don't want to kill the patient" tests, and that assumes that the people speaking can actually explain anything useful to a doctor about their gizzards. ("You see that purple blobby thing over there, with the tendrils coming out of it? Yeah! That's a Qanurkle. It's purpose is to regulate m'shenthain degredation in our Hwiiiinip gland. What does the Hwiiinip gland do? I'm not completely sure, it has something to do with blood sugar. I sure wish our doctor was here!")
And this is assuming that aliens with open sores and bleeding wounds aren't inundated with terrestrial diseases they couldn't possibly be fully inoculated for. I'm a huge fan of Morgan Freeman's paraphrase from H.G. Wells' *War of the Worlds.*
>
> From the moment the invaders arrived, breathed our air, ate, and drank, they were doomed. They were undone, destroyed, after all of man's weapons and devices had failed, by the tiniest creatures that God in His wisdom had put upon this Earth. By the toll of a billion deaths Man had earned his immunity, his right to survive among this planet's infinite organisms. And that right is ours against all challengers, for neither do men live, or die, in vain.
>
>
>
*You did not say that they came prepared to walk in our atmosphere, among our people, unaided by any technological assistance. I am therefore assuming the best they have is general antibiotic assistance and possibly inoculation against the biggies (Polio, Measles, etc.), but otherwise, they're wide open to attack from almost any bacteria or virus.*
Our good medical staff would likely save those with bumps, scratches, cuts, broken bones — so long as they kept the aliens in at least a Hazmat-grade medically clean environment. But anyone needing more than a few stitches is dead before we can analyze enough to know that the latest miracle drug from the world's pharmaceutical companies wouldn't kill them instantly.
BTW, it's a temptation to think, "they're gonna die anyway, what can it hurt? Stick that boy with 20cc's of unfractionated heparin! No! I don't think that's a tumor! I don't care what it is! What do you mean pinching it affects his breathing? *I SAID STICK THAT BOY! NOW STICK HIM OR YOUR...* oh rats, he's dead. *Next!*" But I'm kinda thinking that explaining those actions to the survivors would sound more like Mengele-grade torture-research than it would an honest effort to save their lives. I'm just sayin'.
[Answer]
### Short term: YES
# Long term: NO
Sure, broken bones and bumped noggins can be treated well enough with basic first aid. I can't imagine any deep space observation crew would venture forth without more self-knowledge than a third grader. They may not know as much as their physician, but they should have some kind of idea what their bodies are made of and how they function, what constitutes normal conditions and abnormal.
One thing we need to consider is long term prognosis versus short term. I mean, this isn't like an ER where they splint your arm, take your insurance information and send you on your way with discharge instructions. Is that enough to count them as saved? To fix their immediate wounds?
These people are basically going to have to be, well, "stored" in a superhygienic environment for the rest of their lives in order to keep Earth's environment from killing them. What if their normal life spans are a thousand years? Maybe in all that time we might be able to reverse engineer enough of their starship technology to fare out into space on our own and return to their own people.
Economically, and realistically, this may not be possible. The military will almost certainly confiscate the starship --- no chance of that technology ever becoming open source! They'll probably also confiscate the alien people themselves, assuring the American people that they'll be well looked after.
Long term saving, I think, amounts to not a chance!
[Answer]
It's going to vary directly with how similar their biology is to earth creatures.
If they're oxygen breathers, and can survive, even thrive in Earth's atmosphere, that's going to be a big help, cause it suggests that their biology tracks with ours. That'll increase the chances of keeping them stable with basic first aid.
There's going to have to be a great deal of hasty experimentation. Since there's little to no guarantee that our medicines will work the same on them, tests and experiments are going to have to be made on tissue samples, and if it's an emergency, on the subjects. Antibiotics to prevent infection, and painkillers to provide comfort would likely be the first things attempted.
I think the most important thing to work on, providing we can at least stabilize the patients, is the electronics of their ship. Not as much to recover their medical records, but to get a message to their people that they are injured, but stable, and are in need of recovery.
Now this is all completely ignoring the political aspects of the United States having documented possession of an alien craft, and living (for the moment) alien beings under their care. THAT...is a whole nother question. Perhaps I shall ask it.
] |
[Question]
[
Is there a possible scenario in which once a year a celestial body can be seen from the surface of the Earth-like planet for a short period of time?
* With it being big enough for early civilization to consider it a second moon but much smaller than the actual one.
* And occurring each year for one thousand years.
I thought two moons questions are similar enough, but I haven't found a proper answer for myself.
Thank you!
[Answer]
Yes. That would be a kind of quasi-satellite.
And Earth already has a small one - it's called [Cruithne](https://en.wikipedia.org/wiki/3753_Cruithne). At perigee, a larger Cruithne might well be visible, always in the same section of the sky.
[](https://i.stack.imgur.com/M2EX8.gif)
A larger body would be less stable, but if you only need one thousand years, I think it could work out.
As rightfully pointed out by Ville Niemi, in this context "less stable" might have very, very dire consequences - you might be looking at a [Theia](https://en.wikipedia.org/wiki/Theia_(planet))-like endgame. Emphasis on the "end".
[Answer]
A **comet** could fill this role. Comets are notoriously bright.
[](https://i.stack.imgur.com/v1Fyz.jpg)
<https://en.wikipedia.org/wiki/File:Comet_P1_McNaught02_-_23-01-07.jpg>
I like the tail but you could have your celestial body be made of something more solid, equally reflective, but not falling apart and leaving the tail.
Comets also have very elliptical orbits and visit infrequently. In this [list of periodic comets](https://en.wikipedia.org/wiki/List_of_periodic_comets), 3200 Phaeton has a period of 1.4 years - very short by comet standards.
<https://en.wikipedia.org/wiki/3200_Phaethon>
[](https://i.stack.imgur.com/niNjv.png)
So: your second moon is a very bright short period comet. That seems plausible.
] |
[Question]
[
The question is fairly simple. If a Mongol and a Centaur ride by and shoot at you, who has the better chance of giving an arrow a new home in your gizzard?
That is, given equal skill in shooting, does a centaur have an advantage in mounted archery/shooting? Are they in a more stable position to shoot from and thus more accurate, than a rider sitting on a saddle? Or, would you reckon centaurs would be less accurate that a cavalryman?
Note that horses can run reasonably well [even while blind](https://www.youtube.com/watch?v=gct8D-D4E64), so I wouldn't be highly concerned about their ability to aim while moving.
[Answer]
I’m betting on the centaur. The hardest part of shooting from horseback is knowing your horse well enough to adjust your shot for its gallop. Try a simple experiment with a camera: go shoot some video while running on a bumpy, broken road. Then shoot the same video from a car while someone else drives. Then go to a nearby major airport and shoot some video out the windows of whatever monorail/peoplemover thing they have.
The rail video is smooth for most people, barring a lurch at accel and decel as it enters and leaves each station. It is like you’re standing still. That lurch is because you can’t exactly compensate for the train movements. Now look at the other two videos.
For most people, there will be less camera shake when running. Your hands learn to compensate for signals from your feet for what your feet *are about to do*. You learn car movements secondhand from sensing acceleration *after motion has started*. It’s like the acceleration in the train but continuously adjusted. Horseback is even more variant as the horse crosses terrain.
The centaur knows nir own body. Ne can adjust ahead of time. The Mongol is reading the horse and is always suffering some time penalty, no matter how well trained horse and rider are. So I bet on the centaur.
I double my bet if the Mongol is on a new or untrained horse.
[Answer]
I saw a demonstration of this sort of archery, and I would put my money on the Mongol, the demonstrator put three arrows in the target as he passed, one on approach, one beside, and then he shot another when he was past the target.
The centaur might have trouble twisting for the last shot and they need to control and coordinate 6 limbs at the same time while doing it. The Mongol only has to control his arms, not run and he can smooth the bumps a bit by flexing his knees. Try running and shooting an arrow or even a gun and you would be lucky to hit anything at all difficult.
[Answer]
**Mongol**
A horse has to concentrate on the ground in front of it. Putting your foot down a rabbit-hole or merely stumbling over an obstruction would be disastrous. Therefore centaurs would not be able to keep their eye on the target unless they were on perfectly level ground. That might be possible in a tournament situation but not on a battlefield.
Of course if the horse or centaur both come to a standstill before loosing then there's no real difference.
] |
[Question]
[
## The Question
What would be an efficient and relatively low-cost solution for **collecting and recycling** of space junk?
The most important criterion of effectiveness is the ability to remove even small pieces of junk from the orbit and then put them to good use. Small is on the scale of millimetres.
Deorbiting should be avoided since it is 1) potentially dangerous for surface installations especially without the protection of an atmosphere, 2) wasteful (unnecessary damage on impact and burning in the atmosphere once terraforming progresses to advanced stages).
## Context
A small group of colonists arrives at a moon of a gas giant with a plan to terraform it and build a new life for the generations to come. They aspire to build a sustainable and environment-friendly civilisation that in the future will span over the star system and perhaps even extend its reach to nearby stars.
They start a big-scale mining operation in the nearby asteroid belt and other gas giant moons. Other on-going projects are development and building [artificial magnetic shields](https://worldbuilding.stackexchange.com/questions/90122/habitable-environment-on-a-big-moon-of-a-gas-giant-lacking-magnetosphere) and a satellite network to monitor the moon and coordinate operations. The colony ship was never meant to land, so it stays in the orbit. Smaller vessels are used to transport people and materials to a tiny domed (and partially underground) installation on the surface. The space traffic is not overwhelming, yet. Accidents are very rare but still happen.
The moon originally does not have any debris or other junk nearby. The colonists intend to keep things neat and clean forever. Therefore, they want to put in place a system of collection and recycling for the space junk. They believe that it would effectively lower the risks of accidents in the future when the traffic is projected to increase substantially. They also do not want to repeat the mistakes of their own Earth and take a route of 'irresponsible mismanagement of resources' that almost killed the planet.
Deorbiting and burning in atmosphere bigger pieces of debris is not a valid option since there is no atmosphere yet. Moreover, the colonists want to reuse the materials and technology. The Chief Engineer is a neat freak, so he insists on collecting and processing even the tiniest pieces of debris. His team is not sure it is possible to achieve his standards of sparkling-clean space, but promise to do their best.
## Technological level
The colonists have access to the following technologies:
* fully automated and robotised asteroid mining;
* space travel at 1/10 of the speed of light;
* terraforming technologies (however, only one project has been completed successfully by the time of their departure);
* genetic engineering;
* suspended animation.
Technologies that are envisioned by scientists of today but cannot be built because of technical difficulties (materials, money, political will) are fine. However, something like magic space vacuum cleaner is not possible unless it can be explained by existing science.
## Real-life Proposals
There are some real proposals for my problem. However, I am not satisfied with them because they mainly suggest cleaning the orbit by burning the debris.
**[Project Pac-Man](https://www.seeker.com/an-orbital-pac-man-to-chomp-through-space-junk-1770088139.html)**
An approach and capture system – a so-called “Pac-Man” solution.
Credit: 2015 EPFL/Jamani Caillet.
Originally published on [Space.com](https://www.space.com/30007-space-junk-cleanup-pac-man-approach.html)
This system uses a net cone to capture debris as small as 10x10 cm (4x4 in). It can be launched from orbit and relies on optical scanners to find and capture junk.
The downside is that it is meant to deorbit junk and burn with it in the atmosphere. It is very wasteful. Also, I am not sure if all debris can be easily seen. Moreover, the net design does not allow capturing of smaller pieces.
**[DARPA satellite recycling](https://www.space.com/13339-darpa-space-junk-recycling-phoenix-satellites.html)**
This programme is developed by the US Department of Defense to scavenge parts of satellites (such as dishes) and reuse them. Again, this does not help with small pieces and 'useless' junk that cannot be used as parts for new equipment. It is still a much better idea than burning things.
**[Other approaches](https://www.seeker.com/space-junk-debris-recycle-mars-exploration-satellites-2085063955.html)** include towing junk to other planets (like Mars) to some kind of a recycling facility, using nets and harpoons to capture debris, or just vapourising it with lasers.
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This question is not a duplicate of previous questions related to [Kessler Syndrome](https://worldbuilding.stackexchange.com/search?q=Kessler+Syndrome) or [space debris](https://worldbuilding.stackexchange.com/search?q=space+debris). My focus is on recycling rather than clearing the orbit. It is also important for me to avoid deorbiting.
[Answer]
Unless everthing in orbit is magnetic, the only ways to be efficient are:
* Use the pac-man method. It's the one and only way to collect non-magnetic debris from orbit because there's no atmosphere to push things around with a blower. However, rather than using the single-mouth solution shown in your picture, methinks a three-engine net trawler would provide better coverage. It is a 3D problem, after all, and what you want is the biggest honking net you can possibly get out there.
* Use fully automated drones in a controlled flight path such that everybody (especially including pilots) know where they are. As those nets fill up, the trawler teams become catapults full of bullets. When the nets are "full" (measured by the drag on the drones), the drones come together in front to enclose the mess and form a tug.
* Space-station collection. Don't even try to get this stuff to the ground without processing, first. Your drones will want to take advantage of their orbital momentum to hit the target, which would efficiently use hooks and winches to snag-and-drag the material in. Empty the net, and send the drones back to their pre-arranged route.
And remember that this takes time. Cleaning out a messy high orbit could take months to years. Remember, it's a 3D problem. Nets. Big honking nets.
[Answer]
You'll meet several significant problems when you try to imagine garbage collector like "Pac-man" - pieces of garbage move with relative speeds so high, that they can turn "Pac-man" itself into more garbage on contact, and if you wish to equalize the difference in speeds, you need ridiculous amounts of fuel.
Using lasers to control garbage orbits may be viable option. You don't need close approaches, all you need is ground-based laser (there are agreements that prohibit launching weapons to space, mind it), that can hit 10cm piece of junk from ~500 km (lower orbits are quickly cleaned by residual air drag). Then you either decelerate and deorbit junk (small pieces can't harm anything, they'll evaporate on reentry) or guide it into different orbit for rendezvous with a garbage processing satellite.
[Answer]
**Gather them**
If your civilization has the technology to create a 0.1c propulsion unit then a 0.01c propulsion unit should be readily attainable. With such a powerful rocket a small fleet of robotic craft could match orbits with all of the larger pieces of junk and simply load them on board.
**Absorb them**
The finer pieces would require a different approach if you wanted the task done in a reasonable time frame. One option would be a very large double skinned sphere which was very lightly pressurised. The gap between the skins being filled with some sort of self-sealing goo. Inside there is something that can generate a large electromagnetic field and strategically placed around the surface are some form of electron beam projectors.
This object would be placed in orbit and would aim the beam projectors at any objects in nearby orbits these would then become electrostatically charged and would be attracted to the sphere and either stick to it, get embedded in it or be vaporized and captured inside it.
A sphere would be needed as objects could approach from almost any direction except directly below and at a wide range of velocities depending on the type of orbit.
**Forget them**
Perhaps a better plan (not strictly allowed but…) would be arrange for the Chief Engineer to meet someone he admired greatly who could say to him “We have a lot on mess on the surface and we need it tidied up. We could really use all these people you have working on your project like Olga, A.C., JBH and Slarty. Perhaps the orbital clean up can be delayed until we have cleared the surface a bit. Let me buy you a beer and we can discuss it”.
[Answer]
A small fleet of "double net catchers" might do the trick.
You need an elongated satellite with two Pac-Man catchers at the extremes.
Mareal forces will orient satellite to orbit "standing up" with one end pointing to center of planet.
Lower end would move slightly slower than orbiting debris, while upper end would move a bit faster.
This arrangement would actually sweep orbits while keeping differential speed at a manageable value; this assuming debris follow a regular pattern, much like rings.
Debris collected by sweeping sails would accumulate at extremes where appropriate containers can hold them till next inspection.
This idea is patterned along Niven's "integral trees".
[Answer]
An answer that will satisfy your OCD engineers requirements is available, but EXPENSIVE.
And it will require significant mapping work of the Lagrange points of the gas giant and all of its moons. (You did not state how many moons the gas giant has. I would be surprised if it is less than four.)
The thousand mile view is that over time, loss of delta-v will result in most of the material being trapped in Lagrange points anyway, but this is not a good enough answer. So the process must be accelerated. This means a network of both optical and radio telescopes must be built that scans to a fine enough resolution to establish trajectory data for the space junk. And there must be some fairly hefty data processing infrastructure to do the calculations on radar and image data.
Once you have a database that catalogs the orbital path and projected decay of all the space trash, you can use a combination of two types of space vehicles to implement a solution. The Pac-man vehicle has already been described in other answers.
Another vehicle that can match orbits with a particle and fire either a laser or plasma burst will result in an EDM effect (electrical discharge machining). This has the net effect of sneaking up on a particle and partially vaporizing it. The sudden conversion from solid to gas or plasma accelerates the particle to a new orbit. Larger delta-v values might even be used to intentionally crash the particle to a destination where future building will occur on the airless moon. Defer the problem of collecting the junk till construction is actually occurring and the waste becomes a resource.
I wanna work for this engineer if he has project management savvy to marshall these kinds of resources.
[Answer]
The most effective and efficient way of dealing with space junk is the same for any waste cycle: Keep everything clean and tidy from beginning to end. Cleaning up after the fact is always much, much harder. So, avoid doing it.
Any technical civilization capable of 0.1 c spaceflight and robotic mining should be able to produce and operate swarms of robotic mini-spacecraft. These would congregate around any orbital site of manufacturing or industrial activity including normal space operations. The sensors of these collector vehicles will be extremely advanced by out standards since they are the product of an interstellar civilization.
Therefore, even the smallest piece of material that wanders away will be detected, pursued and collected. In fact, any reasonably organized interstellar technological civilization should be quite capable of fabricating collector craft to meet their junk collection requirements on demand.
A whizomatic wrench floats away from where maintenance robots were doing repairs and a suitable sized and functional collector drone emerges from the fabricators setting off in hot pursuit. Whizomatic wrenches are too big for the usual collector drones to salvage. The flecks of paint and hull material dislodged by those selfsame maintenance robots (really they need to go back to the workshop for a long overdue service) and the usual micro-drones zero in on them for collection.
The collector drones will place all salvaged items and materials in mobile containers for delivery to recycling units.
Not messing up in the first place is always the best policy. If a mess does happen and space junks results, then make sure there are swarms of collector drones on hand to clean up. Also, ensure there is additional capacity to fabricate additional collector drones to handle any junk of non-standard sizes (both big and small). Follow these sensible rules and the Chief Engineer will sleep easy. Perhaps, a book at bedtime and a glass of hot milk wouldn't go astray either to help him rest.
[Answer]
Space cow magnet.
[](https://i.stack.imgur.com/Ktu5w.jpg)
This would not attract space cows (probably) but would be an orbiting version of a cow magnet. These are smooth magnets cattlemen feed to cows. They attract metal the cow accidentally eats and keep it in the rumen, so it cannot go down into the guts and cause damage.
I envision orbiting electromagnets. There would be many, each responsible for its own strip of orbit. They would be cheap: a solar panel, a battery, a big coil and a detector.
As each one orbits it maintains a small field. If it detects a perturbation of this field (because of a nearby metal object) it can ramp up the field. This will hopefully pull the object in to the orbiting magnet or if not, slow it down so it could be collected by a different satellite later. Ferrous objects would of course be attracted but because of the motion of the object through the field, it would induce a current and consequent magnetic field in anything conductive, and so could also trap or at least slow aluminum, nickel and other metals.
The cow magnet is a permanent magnet but the electromagnet will need some structural way to hang onto nonferrous things it pulls in; they will no longer be attracted once still. Bristles?
Metal objects the wrong shape to produce an adequate field or objects which have only small amounts of metal (the rest being rubber, I presume) would still be detected and the space cow magnet satellite could transmit an estimate of the direction and speed of this object. A separate operation (geostationary trash grabber?) could alter its orbit to intercept these.
---
ADDENDUM
from comments below:
>
> This sounds like a good idea for capturing missing bolts and gears.
> But what about plastic, big pieces of ice, and other non-metal things?
> – Olga yesterday
>
>
>
I did not like that I did not know about the ice. Then I stumbled across this:
[](https://i.stack.imgur.com/fslqb.jpg)
from <https://www.youtube.com/watch?v=I2pmV_jjC7c>
Water is diamagnetic and is weakly repelled by a magnet. I did not know this at all! Very cool. Not so cool for the prospects of the space cow magnet sweeping up chunks of ice, though.
[Answer]
First before answering the question we first need to consider a few things about space junk.
First lets define it:
* Space debris would be any artificial objects in planetary orbit that
do not serve a purpose.
Next lets think about the source of it:
1. satellites that have reached the end of their lives
2. spent rocket stages
3. debris from stage separations (bolts, paint and other various small bits)
4. fragments from the breakup of large objects (such as collisions, accidents)
5. intentional destruction of satellites, such as Anti-Satellite missiles or sabotage.
There may be other sources of space junk, feel free to leave a comment!
Now I ask these questions basing on what conditions you set forth originally
>
> * The moon originally does not have any debris or other junk nearby.
> * They believe that it would effectively lower the risks of accidents in the future when the traffic is projected to increase substantially
> * Accidents are very rare but still happen.
> * fully automated and robotised asteroid mining;
> * space travel at 1/10 of the speed of light;
>
>
>
Now:
As this seems to be a peaceful situation we can almost entirely remove #5, even if we can't these would be fairly rare events.
It's a reasonable assumption if they are capable of interstellar travel, that they are no longer using multi-stage to orbit space craft. This would eliminate 2 very large sources of space junk, #2 and #3.
These are very important considerations because solving the problem depends on the scope of the problem. Here we can see that the actual problem ( in this case ) is relatively small and if managed early should be trivial. Let's look at the last 2 sources.
1. satellites that have reached the end of their lives
This is either a predictable event, a satellite has been replaced with an upgraded system and so it is now obsolete. Or, it is an event caused by some kind of malfunction/accident/sabotage that renders the satellite inoperable. In each case the "Authorities" would know pretty quickly and could dispatch a robotic probe to go and pick it up.
4. fragments from the breakup of large objects (such as collisions, accidents)
Again this wouldn't be a big mystery when it happens. The challenge here is that the longer it takes to clean up the mess the further dispersed the debris cloud would be. So interest could be added here by highlighting the sense of urgency in the cleanup window. But, even still, it would be a relativity simple matter to collect the "larger pieces" even smaller bits if caught soon enough would be pretty trivial to clean up ( for a civilization at this level of tech ). The DeltaV ( or effort assuming actual fuel is not an issue ) is greatly reduced before the debris has a chance to spread out along individual orbits. I am not sure how long dispersion would take, it's probably a function of the energy involved in the breakup. Even in modernly powerful breakups, the bits would continue mostly on their original orbit. Even if a ship was to breakup on its way to the planet, most of the bits would follow it's original path and eventually hit atmosphere. You may be able to disregard orbital mechanics for things like transfers to other moons or planetary bodies but, orbital mechanics needs to play a large role here, because these objects are drifting un-powered.
For smaller dispersed bits ( or even a cloud of small bits), I think it's entirely reasonable to deorbit and allow them to burn up. I wouldn't be economical to collect these bits, and because they are dispersed you would need to cover a much larger part of the orbits. So you would want something very cheap and mass producible. The environmental impact would be very minor as they would vaporize in the upper atmosphere.
The idea I had to deorbit these types of debris would be a very small well armored space craft, attached to a very large sheet. Think something like the solar sail ideas. Now the sheet would need to be made of a material that allows for many punctures of it without affecting its overall strength. We don't want large chunks shearing off or even tiny parts. Basically you could puncture it but it won't tear. Maybe something with a cellular or honeycomb feel to it.
Now you might think how will a large sheet (maybe the size of a football field or larger) that can be punctured but not tear be used to deorbit small debris. Here is how, you launch it retrograde. Most if not all orbits will be along the rotation of the planets axis and not far from the plane of the equator. Even with higher technology, this is more a matter of orbital dynamics ( think geostationary orbit ) than anything else. So when these small bits puncture the membrane of the craft moving in a retrograde orbit they will blast through the membrane at an incredible speed, but in doing so they will lose quite a large amount of their own velocity. Possibly even enough to cause them to deorbit.
There is some risk with the "screen" for lack of a better name, would suffer some kind of failure it self. In the case it hit some odd bit of large junk (easily predicted with their tech), both parts would probably deorbit. Because of the light weight ( low mass ) nature of the screen it would naturally deoribt over time as it collides with the bits of junk and loses speed. It could also be built specifically with it's eventual deorbit in mind, so that it would burn up in the upper atmosphere as well. This would be done by putting it in a more eccentric orbit that grazes the upper atmosphere on the perigee of the orbit ( the lowest point ), this drag over time would decay the orbit naturally.
Another idea would be to use a elliptical polar orbit to sweep the normal orbits of debris, but in this case a flat sheet probably isn't the best geometry for the screen. A polar orbit would be good because it would cross many other orbits over time, with each intersection having a small chance of colliding with a bit of junk. The effect would be less from the collision, because it's perpendicular not reverse, but certainly some orbital energy would be lost. One consideration is this could actually make things worse by changing the plain of the derbies and actually spreading them out more. But I will let you worry about the fine details like that.
The only real challenge in this would be keeping the screen perpendicular to it's orbit. However, a 3D shape ( such as a sphere ) could also be used instead of a flat plain. To me this is largely a minor detail, given the advanced tech they have and the simplicity of the "screen" craft.
Anyway, those are my thoughts.
* For large bits, clean them up quickly with robots. Recycle units etc.
* For clouds of small bits, hit them with the screen moving in a retrograde orbit which will cause their orbit to decay.
Something that also occurs to me, is that if the main concern is traffic. You should spend some time integrating how their "shipping lanes" and traffic control work. This can take inspiration from many places, like airports etc.
You could work in a few scenes where the "actors" are stuck waiting for a launch window, or have to wait for some large ship to clear the shipping/traffic lane. You could do scenes that actively incorporate the "control room/tower" of the traffic system. It could be a plot item where someone sabotages the traffic system etc. etc.
Basically prevention should be an equal if not larger part of this effort, with mainly "accidents" accounting for most if not all of the "problems". And then the odd malfunction or sabotage here or there to spice things up.
One last thought is that craft traveling at even 0.1c should have some kind of shielding. Think "deflector" but not in the Trek sense. Basically a field to push space dust out of the way, this could even be a byproduct of an advanced engine that warps space. So the idea here is clean up the large bits and just ignore the small bits. As these, would be pushed out of the way of the ships by their space warping drives ( or deflectors ).
Anyway, hope that gives you some ideas.
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> The most important criterion of effectiveness is the ability to remove even small pieces of junk from the orbit and then put them to good use. Small is on the scale of millimetres.
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Differently sized pieces of debris will require different types of "catcher". For large pieces, you will need to match orbits and use some kind of grapnel or robotic arm. *And* you'll need some means of controlling their rotation/tumbling. For metallic objects you can use [Foucault brakes](https://en.wikipedia.org/wiki/Eddy_current_brake). Otherwise you can try with electrically charging the surface and use electrostatic pulses, or shooting adhesive, metallic goo on the objects and then use Foucault brakes.
For the next step, we need an important condition: **all the debris is orbiting in the same direction - either same as the moon's rotation or opposite to it**. If you have *both* then this will not work and you run a considerable risk to operations.
If all objects are orbiting in the same direction, objects in the same orbit are **still** in respect to one another (otherwise, they're *hurling against one another* at a speed equal to the square of 4GM/r, with M the mass of the moon and r the orbital radius, and you *really* don't want to be there).
But in our scenario, all you need to do is enter an orbit a few hundreds of meters above or below the one(s) you want to sweep. Objects above will appear to drift toward you, objecs below will appear to gain ground and approach from behind - all at manageable speeds. You drop a pair of large unfolding butterfly nets made of conducting wire, one above and one below, with lightweight struts to keep them in position. Now you start spraying electrons towards anything approaching. This leads to the building of a large positive charge on the nets' surfaces, and the incoming particles having been negatively charged, they will be trapped.
Electrostatic traps are capable of filtering particles smaller than dust, and at those speeds, larger particles present no problems. So you're pretty much set up for a clean sweep.
There will be an appreciable tidal force trying to push both nets until the craft has rotated 90 degrees and is all contained in the middle orbit; you'll need some ACS, possibly based on a counter-rotating disk, to keep the craft's axis directed towards the moon.
When the net is full, you just bring it in for recycling. But since there are no considerations of air resistance etc., the net might well never get "full", and you could be happy harvesting it once a year or so.
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Project Rho has this picture:
[](https://i.stack.imgur.com/cC69r.jpg)
The idea was to suck up the space debris, crush it and shoot it out the back. It was not specified how it was powered but if you can go .1 C you'll probably be able to power it. However, this machine is not built to recycle debris and is only for small objects that cannot be easily shot down by lasers.
EDIT:
On Project Rho: Atomic Rockets the page where I found this was <http://www.projectrho.com/public_html/rocket/civmilitary.php>
And the page about this is
<https://www.technologyreview.com/s/544156/junk-eating-rocket-engine-could-clear-space-debris/>
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## I propose a double light web, and a (quite distant) robotic 'catcher' grid.
Things in orbit move in nice predictable orbits, at least in the short term, and are only slightly affected by the gravitation of other objects in orbit.
### One Light web:
What we want is a pair of bright lasers (not **powerful,** we don't want them to damage anything) with some hi-res video cameras. They sweep a plane of a large area. If they hit anything, the reflection is picked up as a flash by the video camera. With a few cameras, we can triangulate where exactly in the plane the object appeared.
### Another Light web.
This does exactly the same thing, in another plane a few yards from the first, and parallel to it. The line from Plane 1 to Plane 2 gives you the trajectory of the space junk passing through the planes. The time between penetration of Plane 1 and Plane 2 gives you the speed of the object on that trajectory. At the speed of light, this can be communicated 1000 miles away to a grid of garbage cans, spaced perhaps dozens of yards apart. Exactly when and where the space junk will reach the grid of garbage cans can be computed, and the garbage can closest to where the space junk will be uses retro rockets to put itself in the path, catch it, and return to its original position.
All of that can be roboticized.
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Why do you need to collect and recycle? You can't be cost effective when you are trying to catch objects that are millimeter sized. There simply isn't enough material there to justify the effort.
You need to remove the material from orbit but catching and recycling it really isn't cost effective for anything beyond the largest of objects. It's more cost effective to mine another asteroid than collect paint chips and dust.
Now assuming I had to catch and recycle for whatever reason, I'd build a trap which would be like a solar sail which would orbit the moon. It would have to be strong enough not to tear and sticky so small objects would adhere after hitting it, kinda like giant fly paper. I'd then have small spider like robots that roam the surface collecting the bits and returning them to a central repository for collection.
The robot spiders could also maintain the trap should it get damaged.
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It might be too hard for your target civilisation or take too long, but this is the ultimate approach.
# Place the moons right
The idea is to place additional larger satellites – not even asteroid size, but larger, Moon or Ceres sized – into the orbit. They will basically sweep all the small space junk either into the atmosphere, or outside Earth orbit, or into the few Lagrange points, actually Trojan points, if I recall correctly.
More or less Jupiter does a similar job for the Solar system.
And this setup will keep the orbit clean. The drawback is, of course, the cost and feasibility of initial setup.
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From pictures I've seen, all rocky planets in our solar system are some shade of grey, brown, and red. Ignoring stuff like atmosphere and oceans and plant life of course.
I was thinking of a world that had a stark white moon. But could such a thing exist? The only 'white' moon I know of is Triton, and that world is covered in ice. I highly doubt a planet in the 'Goldilocks zone' could have a frozen moon.
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There are various compounds in nature which are white.
One of these is [Titanium Dioxide](https://en.wikipedia.org/wiki/Titanium_dioxide)
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> Titanium dioxide, also known as titanium(IV) oxide or titania, is the naturally occurring oxide of titanium, chemical formula TiO2. When used as a pigment, it is called titanium white.
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Another of these is [Lead Carbonate](https://en.wikipedia.org/wiki/White_lead), or white lead
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> White lead is the basic lead carbonate, 2PbCO3·Pb(OH)2. It is a complex salt, containing both carbonate and hydroxide ions. White lead occurs naturally as a mineral, in which context it is known as hydrocerussite, a hydrate of cerussite. It was formerly used as an ingredient for lead paint and a cosmetic called Venetian Ceruse, because of its opacity and the satiny smooth mixture it made with dryable oils. However, it tended to cause lead poisoning, and its use has been banned in most countries.
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Now, to have a white looking moon, you don't need the entire body to be made of this material, but just to have the surface layer being covered with it. Which helps if your material is not that abundant.
Parking aside the issue of abundance, you need to cope with depositing of other dust, which will be most likely not be as white as the background.
So, it is possible though not highly likely. And even then, without a mechanism constantly refreshing the white surface, it won't last long.
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The obvious answers are ice and clouds which could easily give a planet or moon a white appearance. If you require some other type of white surface then quartz can be white and is very common. Crushed coral can also produce white beaches. But your biggest problems will be if you want the place to be inhabited. In this situation you probably need seas or oceans to some extent which would are certainty not white, as well as vegetation coverage which would also not be white.
Probably the best bet would be to arrange the water content of your world to be low, have it fairly close to the sun and have a larger proportion of that water there was high in the atmosphere creating white clouds, a bit like Venus but at a much reduced pressure and without the toxic components caused by volcanism.
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There are white rocks on earth, many of them in fact, I used to work in the [white river formation](https://mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=WYTwr%3B0) and the rock is so white you can get a sunburn from reflected light alone. It contains a lot of calcium minerals and volcanic ash.
[](https://i.stack.imgur.com/eE9U7.jpg)
here is what it looks like close up, keep in mind this is a color photograph.
[](https://i.stack.imgur.com/EtCAn.jpg)
There are many white rocks so it is not unbelievable to say your moon just happens to have an abundance of them.
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Building on @Slarty 's answer, ice and clouds could very well give a planet a stark white appearance.
Its worth noting that a star's light shining on the surface of a planet could amplify the white of the surface.
The problem arises if you want your planet to be habitable.
Seeing as you've mentioned the Goldilocks zone in the question, I'll be assuming you want it to be habitable.
Thankfully, we have a real world example to help us here.
Saturn's moon, Titan, has a completely ice and water covered surface. Research suggests that there are large oceans under the surface, that might be very similar to those of Earth's.
The temperatures near the ocean bed are generally stable enough to support organic life.
Dense white clouds could also be a sign of a thick atmosphere, holding in heat and essential UV radiation to make life possible.
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This is one of a series of questions also discussing [mosquito prevention](https://worldbuilding.stackexchange.com/questions/68789/mosquito-protection-for-an-ancient-rainforest-civilization) and [city building](https://worldbuilding.stackexchange.com/questions/73497/can-a-city-in-a-flood-plain-be-maintained-for-centuries-if-it-is-built-on-stone).
There is a civilization indigenous to an area like the [whitewater flooded forests](https://en.wikipedia.org/wiki/V%C3%A1rzea_forest) of the southern half of the Amazon basin. This civilization is in the Bronze age.
The forests are in a six month wet-dry cycle, with water level in forest going up and down by about 10m. In the 'dry' season, the people plant maize, beans, and sweet potatoes on *terra firma* on the edge of the floodplain as soon as the water levels drop. In the 'wet' season, these people will make floating gardens in which they plant [arrowroot](https://en.wikipedia.org/wiki/Maranta_arundinacea), [leren](https://en.wikipedia.org/wiki/Calathea_allouia), and [runner beans](https://en.wikipedia.org/wiki/Phaseolus_coccineus) (as well as vegetables, like tomato and chilis).
The selected of plants will need about 1 foot of soil to grow, preferably 2 feet. The floating farm would be filled with soil each year as the water levels rise, and then emptied during the dry season. A re-usable structure would be best. These floating farms are kept in the flooded forest area outside of the main streams, 'moored' to various tall trees; [Acai](https://en.wikipedia.org/wiki/A%C3%A7a%C3%AD_palm) or [Kapok](https://en.wikipedia.org/wiki/Ceiba_pentandra) are often planted for this purpose. Stream flow rates are negligible for most of the season, its more like a lake, so the structure does not have to be that strong.
My question is: **how would a floating farm be built, and how large would these farms be?**
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The Mayan created "floating" farms called Chinampa. But you want real floating farms to handle flooding, the good news is they already exist and have for centuries. Actual floating farms to deal with massive flooding has been used extensively in Bangladesh for centuries.
First you make a bed of reeds and bamboo and a thin almost sprinkling of soil followed by another layer of reeds and farm similar to hydroponics. You can read a more detailed account of how they are made and used here. <http://www.irinnews.org/report/90002/bangladesh-spreading-floating-farms%E2%80%99-tradition>
<http://www.fao.org/climatechange/17849-0e277b46b31f98942e6bc81bb22319243.pdf>
and a great cross section here <http://practicalaction.org/floating-gardens>
Note that besides vegetables floating platforms also make for very good fish farms.
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**UPDATED**
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> For Bronze Age
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Mostly a suspended platform from a great height for growing the runners/crops can be an option, for example using a suspension rope/bronze cables between a valley. Floating is out of the option for BRONZE age unless you are writing a fictional historic novel that contains some sort of magic/voodoo or if someone from the future is travelling back to B Age and giving you advanced tech.
Also i feel answer by @John is completely valid and should be an accepted answer
**ALSO** : JUST IN CASE ANYONE NEEDS IT FOR FUTURE AGE OTHER THAN BRONZE AGE
You could make a `MAGLEV farm field`, but before that you need to drain proof your field that would need a fail safe plan.
By drain proof i meant to make the field effectively transfer liquids all over the field without leaving an inch of it partially wet/flooded.
To make the farm environment friendly you could power it by using `renewable power resources`.
According to the query :
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> these people will make floating gardens in which they plant arrowroot,
> leren, and runner beans (as well as vegetables, like tomato and
> chilis).
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Seems perfect to me because runners and crops are light weight and there would only be small payload on levitating gardens/farms unlike big trees.
A small example is given below, for now its a show off/ display material but for future earth/mars this could be a viable solution :)
[](https://i.stack.imgur.com/ojiLg.jpg)
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Assume that you've conquered the issue of flotation, probably using some very-much-lighter-than-air gas bladder, allowing your ships to take to the skies.
Assume also that you've invented a way to maneuver effectively in the air using only the wind and sails. The sail (or hull) design isn't necessarily identical to ships of the age of sail, but is limited to that level of technology/materials.
Most importantly, assume that traditional age of sail canons are not possible due to the sheer weight of the metal shot & barrels (and powder too, I guess). The ship can indeed float, but we do have to be relatively weight conscious. I would allow a bit of flexibility here in terms of what was known/possible in the age of sail.
What are some other possible forms of weaponry that these air ships could use to do battle in the skies? And what would you use to defend against that suggested weapon?
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Besides the obvious like Bow and arrow, harpoon etc. you could use parabolic mirrors as weapons.
The Mythbusters once checked a myth that said it was possible to get a ship to burn with mirrors and, while they declared it busted that was only because it took too long. If this works on wood it should work on the air bladder/sails much faster. And by attacking from the right side you make sure that the enemy can't use his own mirrors (should he have any).
As the mirrors need to be focused they'd mainly work on one fixed range, give or take some, and most likely it would be a range lower than that of a longbow but it might give such a world some special flair, where not only the direction of the wind is relevant (as it was for sailing ships) but the direction of the sun, too.
You could make this more probable by having the stuff that makes airbladders air-tight be black or at least dark so it heats up quicker.
That would give you a means of protection, too in covering the bladder with white or even reflective stuff. That would lead to the glorious white ships of kingdom X being next to immune to the weapon of choice, while the dirty looking other airships are easy prey.
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Pneumatically fired harpoons.
The weakest point on the air ship is the gas bladder, so that would be the obvious target.
A hand pump should be technologically possible, and considering the propulsion method is by wind and sail, a trained crew should have time to pressurize the harpoon barrels before engaging.
The barrels will be far smaller and lighter than cannons, with a weightless propellant. The ammunition is also reusable.
The harpoons themselves should be barbed and bladed, fastened to the firing ship by rope:
1. If it misses it can be retrieved (Conservation of ammunition is essential considering the weight limits)
2. If it hits the target's bladder, the crew can tug the rope to tear at it.
3. If it hits the ship itself, boarders can zip-line over to the target, capturing or sabotaging it.
Defense would be difficult considering the weight constraint won't allow covering the balloon in plate or chain thick enough to prevent a tear.
One could:
1. Have an array of smaller disposable balloons (maybe carrying a wooden plate) that function as a shroud against incoming fire.
2. Have pocketed/sectioned gas bladders. This prevents a single hit from sinking your ship, as well as making in the fly repairs possible.
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I've been conceptualising a story involving just this sort of technology for a while now, and I've had a number of ideas for the weapons that could be used.
One of the simplest ideas is **wooden cannon**. This might sound insane, but is perfectly plausible - a cannon with a thick, wooden barrel. Functioning in the same manner as a normal naval gun, but many times lighter. The main disadvantage of these guns is that their lifespan is greatly diminished compared with their metal counterparts, and they are more prone to failure after regular use. This won't be a problem if your airships return to a safe port for resupply on a regular basis. There need be no waste either, as the wood from used/expired guns could be repurposed for other means afterwards. Another advantage of wooden guns is that a crew used to naval warfare would already be familiar with their operation.
In terms of the weight of their shot (cannonballs etc.) the Chinese used a projectile called *bo-hiya* - a large flaming arrow that was fired from a conventional cannon. There are plenty of options that don't require hurling balls of metal at each other.
Ballistic trajectory weapons such as **catapults** or **ballista** are another option. Much safer than explosive weapons (fire is bad on a naval ship; on an airship it is many times worse!) and able to fire shells, large bolts, or even just piles of nails, they are extremely adaptable. The disadvantage here though is that their slow trajectory limits their range and accuracy, and mounting them under your gasbag with a clear line-of-sight is difficult.
**Rockets** were invented by the Chinese centuries ago, and are another viable option. Requiring virtually no heavy firing apparatus (a simple tripod is just about it), these can travel great distances at reasonable accuracy, and inflict massive damage on opponents. However they require competent gunners to calculate the correct fuse lengths.
**Gravity bombs** are very simply large objects that you can drop on to your enemy. Imagine the damage a tree trunk would do, dropped vertically from a great height - it would punch a hole not just through your enemy's gas bag, but probably straight through their deck as well! Whoever has the greater height will undoubtedly have the advantage in a battle. Explosive shells and grenades could also be dropped onto enemy ships.
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For the age of sail, I assume you are talking about the classic "Man-o-war" with decks of cannon firing heavy shot to smash oak planking and shatter huge masts. These weapons were developed in response to warships becoming larger and heavier, so the evolution of firearms on airships would reflect the evolution of airships themselves.
Since combat between airships would take place at longer ranges, and involve greater relative speeds between the ships, cannon would not be short barrel Carronades, but rather elegant, long barrelled weapons with small calibre rounds optimized for high velocity shot. These cannon might even be rifled, to increase accuracy and provide a predictable trajectory.
At the longest ranges, single roundshot would suffice, providing the longest range and most accuracy. As ranges close, the crew could switch to chainshot in an attempt to strip away the control surfaces or do massive damage to the gas bag, and finally, a shotgun like load would be used at close range to ensure a hit and lots of damage (similar to canister rounds to sweep the deck).
As an alternative, a series of small barrels (perhaps 1") could be mounted on a common frame and fired sequentially by sweeping a match across the breech of all the guns. This provides a spray of shot which would be hard to avoid.
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It seems unlikely, barring some BIG advances in zeppelin technology, that you would have zeppelin vs zeppelin combat, certainly it was absent (or very very rare) in real life. If they have a very limited lifting capability then they have a very limited war making capability. Even if you could fill the skies with them, if all they can carry are a few light bombs their effect would be marginal outside of their traditional role as spotters/recon. [Here](http://www.firstworldwar.com/airwar/bombers_zeppelins.htm) is a nice history of their use in WW1.
But if they DID fight each other, you would probably have sharpshooters picking off opposing crewmen and possibly boarding actions by landing men on the top, who then could rappel down. Assuming in your alt history planes have not yet been invented and long range air defense artillery hasn't caught up, then zeppelin vs zeppelin is really the only option. Even machine guns are relatively ineffective against a military multi-celled zeppelin. Only incendiary bombs or killing the crew/damaging engines would be effective. The former requires a higher altitude (and would be VERY hazardous for defending zeppelins if they are over their OWN territory!) and the latter requires getting close enough for precision rifle fire. Boarding parties could rappel over the side and attempt to use grenades or even hand to hand to disable the engines or kill the crew. The benefit for the defenders is that they could parachute down to friendly ground (the parachute was invented in the late 1700's) at the end of the attack.
Another option would be releasing balloons with incendiary explosives, hoping to have them crash into an approaching zeppelin. But this seems like an extreme last ditch defense (unless they have an altitude sensing detonator like a primitive flak shell).
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The OP mentioned a roughly "age of sail" level of technology with some alternate history in there to permit early development of lighter-than-air flight. This is a kind of Steampunk.
**Chemical and biological weapons**
People have known about noxious substances for a very long time. Perhaps they did not know of their true manner of operation, but they knew that catapulting dead animal carcasses into an enemy fort could cause an outbreak of disease.
Airships could be loaded with chemical and biological substances - maybe vats of acid that could be poured out onto ships below (*leading to dogfights in which "getting on top" is key, as opposed to 20th century fighter dogfights in which getting behind is key*), or water balloons filled with whatever poison floats one's boat (or sinks one's enemy's). Ships holds' could be filled with trash and decaying waste products to be used as ammo in catapults and slingshots. There's nothing like another trip to the dump to reload. Even the rotting carcasses of enemy soldiers could be used, or possibly even one's own dead soldiers.
**Gliders**
Ships could be equipped with basic gliders that could be launched in order to land boarding parties on other ships. This would be another case where "getting on top" would help, since the gliders would be unpowered. Once a boarding party has landed, they could use more conventional age of sail weapons like swords, muskets, and bows and arrows.
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**Laser technology**
Only the energy stores are the weight question, but I believe it is competitive with mountings of any projectile weapon, ammo, and gunner crew. If targeting is done by computer and mirror system, even less crew is necessary. Depending on the volume and mirrors, even broadsides can be freed up, and just a few or single laser battery is needed.
Defense: If this loadout gets popular, or standard, specialized marksman forces can attempt to destroy the battery mirror, or render it unusable. Clouds, humidity, dust, reflections can be used as direct defense against laser beams.
**Grapple warfare**
Imagine timed bombs with reeling system attached to a grapple, shot on enemy. Defend with EMP or athlete crew.
Dismantle/sabotage pirates disabling enemy ships. Just like shuttle boarding, but can be done without entering the ship. Defend is really per situation. Several ways of application ban be worked out for this.
**+ Ablatives** (it did not felt as so separate branch from grapples)
using widebroad selection of corrosive materials.
**Shurikens**
From size of handweapon, to rifle, ballista. It can cause severe damage to sails, living organizations. Sadly it has high chance on causing further damage on the environment below the skies.
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During the First World War [German Zeppelins](https://en.wikipedia.org/wiki/German_strategic_bombing_during_World_War_I) carried out bombing raids on Britain. Initially they were extremely difficult to shoot down as the aircraft of the time used rifle-caliber machine guns which, although they could easily hit and penetrate the balloon envelopes only made small holes and as the lift gas was at ambient pressure the rate of leakage.
Eventually they were able to exploit the flammability of the hydrogen uses as lift gas by saturating them with a mixture of explosive and incendiary ammunition, shredding the envelope and igniting the escaping gas.
However if they lift gas is non-flammable you have a much more diffcult task, as you need to do quite a lot of damage to the envelope to make it leak enough that it 'sinks' befoer you do. Here [chain shot](https://en.wikipedia.org/wiki/Chain-shot) and [canister](https://en.wikipedia.org/wiki/Canister_shot) may be the most effective solution.
Although these still need cannon you aren;t relying so much on a huge amount of kinetic energy to penetrate a heavy wooden hull so much lighter cannon may be effective.
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[Question]
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If people time-travelled back to when Earth had a lot more oxygen in the atmosphere (35% instead of today's 21%) what would be the effect when they started shooting? Mainly small arms.
Would spent shell casings be setting things on fire all over the place?
[Answer]
This article somewhat addresses this (it is a complicated read though)
<http://www.fs.fed.us/ne/newtown_square/publications/other_publishers/OCR/ne_2004_wildman001.pdf>
It talks about fire spread during the 35% O2 concentrations of the Paleozoic era. Their conclusions, if I interpret them correctly, is that flammability and fire spread would be somewhat increased but not dramatically so. Even today shell casings landing in very dry materials can start fires so I would imagine this would be slightly more likely in a higher oxygen concentration.
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I would be very surprised if there was any effect.
The bullets won't care, they aren't being propelled with atmospheric oxygen in the first place.
I do understand the threat of hot brass and the stuff that comes out the barrel (watch a gun in very slow motion--there's some fire along with the hot gasses) but if the environment is such that a minor ignition source can set it off I would think it would likely have burned from a lightning storm.
If things were tinder dry it would be more dangerous to use a gun then than in similar conditions now but you don't have that sort of situation in the first place.
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Interestingly, I haven't been able to find a real number for just how hot shell casings are when they get ejected. It's clear that they get hot enough to sting, [especially in cleavage](https://www.youtube.com/watch?v=SQ1Vz-ii9n8), but that's not really an adequate consideration. I can only speculate that, since ejected brass does not significantly oxidise, it is unlikely to be hot enough to set most matierals ablaze, even at high oxygen concentrations.
Certainly, there would seem to be considerable cooling during flight, since the walls of a cartridge are very thin and would cool rapidly.
Perhaps of more concern would be muzzle flash when firing from the prone position, although the flash duration is so short that I'm very dubious that solid materials would be affected.
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I would think the explosions would be a touch more efficient and explosive.
Not by much, but enough to cause a poorly made weapon to shatter in the user's hands or blow apart.
Doubt that spent casings would ignite anything with more risk than they do now.
More oxygen doesn't make materials more flammable 'without a equally higher ratio of fuel to burn or alteration of materials to drop their flashpoints enough'.
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For this question, I'm using the magic system discussed [here](https://worldbuilding.stackexchange.com/questions/39715/limitations-of-magic-as-an-energy-conversion-process) that I will sum up with this: you take energy from your environment (e.g. heat from the atmosphere) and transform it into another form to cast a variety of spells. The spell itself must be either pure energy or resulting from said energy.
One particular spell is hard light, which is the purpose of this question. However, I'm having a hard time determining how I could generate hard light in compliance with the rules of my universe.
So here is what hard light is and isn't:
* It is solid. Not necessarily in the physical sense of the word, but hard light collides with any physical object, include other hard light objects.
* It glows. It generates faint light (as opposed to reflecting it).
* It is cold. It isn't a freezing hazard though.
* It does block what a wall would block. Besides, physical objects, *this includes energy, e.g. heat.*
* *It doesn't block what a wall wouldn't block. E.g. radio signals.*
* It only causes blunt force trauma, much unlike a light saber.
* It is a constant-cast spell. If the caster stops casting, hard light dissipates. *Ideally, does not persist, though it could take a few seconds to dissipate.*
* *It is moderately translucent, as in opaque glass translucent.*
* It is not a block of ice. That would be just too easy.
* It is not solid light, unless solid light actually exists and would meet other requirements.
I've noted in italic requirements you can play with if you have to.
The rules of magic here are:
* Assume magic always works as advertised.
* Assume the caster is not hurt by their spells.
* Assume there is always just the right amount of energy to do what you want to do.
* You can only transform energy. As such, a spell is energy, a discharge of energy or anything energy-related.
* Outside of the aforementioned magic, assume rules of physics apply.
Given all that, what could be the physical nature of hard light?
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Hard light could be pseudo-matter made up of 'virtual atoms' - electron shells without a nucleus. This could be done by controlling electromagnetic fields. Such material could simulate most properties of matter, such as specific heat, hardness, and transparency, but would be almost massless.
Things glow when their electrons drop to a lowered energy state. Presumably keeping the electrons in place requires a constant input of magical energy; when you funnel too much energy into the construct by accident you need to radiate it off as light to keep the construct from dissipating. Perhaps the glow of such a construct could indicate the fine control skill of the mage creating it; glow implies wasted energy (this will be the case no matter how you explain it). A truly skilled construct will have a glassy appearance with very little glow, but even a talented mage might have difficulty controlling their output when they are forced to channel more energy than they are accustomed to.
The construct could be as cold or as hot as you like, but cold implies that the virtual atoms are held firmly in place and the construct is stable, while heat suggests that it is starting to break up.
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If I can take the liberty of turning 'it radiates cold', which doesn't make thermodynamic sense (coldness isn't a physical property, just the absence of heat, which is), into 'it absorbs heat', which is presumably what you mean anyway.
Postulating hard light as a 'portal' with a membrane that only allows massless particles through. Or glass or somesuch, which allows you to set how translucent it is. Then further saying that it has a dim light source at the centre. In other words, so far it's a light source created from transdimensional photons with a translucent pane. This makes everything except for the heat bit work.
So, to fix this: have the membrane full of micropores. Say, slightly bigger than a water droplet (adjust to taste), then have a vacuum of the extremely cold outer space variety between the transdimensional light source and the membrane. Things like hot air currents etc. would get absorbed by this. The only issue left would be infra-red radiation, which could be solved, if desired, by the light source being a crystal that absorbs infra-red frequencies (condensed matter physics allows this). When I say 'absorb', I mean a reverse Unbestanum process. Precise regulation of number of micropores and heat of the source would hopefully be enough to not freeze things and for reasonable pressure regulation. Previously warm molecules then come out again as cold molecules having lost energy, which also helps prevent pressure issues.
Edit:
To clarify, the cooling by convection doesn't work because the vacuum is cold, but because it is a vacuum: relatively small pressure inside causes any particles that fit through the micropores to go through and get absorbed by the reverse Unbestanum process. This includes warm air molecules. As already mentioned, these then get emitted as cold molecules, which also allows for finer control of the temperature and pressure.
Also worth mentioning is that when the process of constant molecule absorption stops, the membrane will automatically collapse inwards.
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Your rules preclude your simply conjuring up matter where there was before. However, it doesn't have to have anything to do with light/photons; it might be called that because of its appearance.
Maybe you can cause the gas and any suspended dust particles to be locked in place. Air would be as solid as a wall if you couldn't move past it as it doesn't flow around you.
It's cold because the continuing spell prevents molecules from moving: thermal energy transferred to it would normally make the molecules move faster, and the spell dampens that. Thus, it serves as a cold sink, which constantly drains the spell.
For whatever reason it's cold, you can run a [sterling engine](https://en.wikipedia.org/wiki/Stirling_engine) off of it, thus it's a source of power. I expect this will require energy to keep it going and/or make it run out.
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So the spell has to be pure energy or the result of a pure energy event.
Scientifically we've been able to [slow light](https://en.m.wikipedia.org/wiki/Slow_light) down to a crawl and even stop it.
Using a pure energy magical field you could make the same effect, manipulating energy in an area to the point that light almost stops, though some does pass through and out of the field eventually which causes a glow.
The one problem is the blunt force trauma part, since photons are massless, and even held together in a field may behave more like a gas than a solid. However if the magical field is slowing down an area of spacetime enough to slow light, it might effect the other things in the area equally, so solidified reality.
Also you can say that once the field is established that it's self contained and while air can flow around it, anything solid like a wall, head, etc. would be excluded from the area until the casting stops.
Another possible idea is if you started the field inside of a solid object, so that the field would anchor the object to reality.
Could be used as climbing anchors that don't leave marks once the spell finishes, or to seal a door so there is no way to open it as long as the spell is working.
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I take it you want a plausible "physical" explanation for what the magic does, while keeping the magic magical. Kindof like how all of Superman's powers can be explained by an ability to change the momentum of matter.
In the case of hard light, we could propose that magic is changing the **vacuum energy** in nearby space. The energy of the vacuum is increased and then guided into a **spontaneous symmetry breaking**. We get a new vacuum state where the Higgs field now couples to the photons, giving them mass. This vacuum, having a higher energy than our normal vacuum, is unstable and decays into normal vacuum when the magic is paused or the light travels outside the magicians's sphere of influence.
Scientifically speaking, the magician is creating a local **[false vacuum](https://en.wikipedia.org/wiki/False_vacuum)**. Simply speaking, the laws of nature have changed in some small area around the magician.
**WARNING:** Care should be taken when altering the vacuum. If a vacuum with a lower energy state is created, it can cause a cascade effect where the rest of our universe drops into the same low vacuum state. The laws of nature in this new vacuum can be very different from our own. There may even exist vacuum states where (gasp!) magic no longer works!
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Earth, far future: We built multi generation ship which can get 20 000 people to another solar system in next 20 generations (600 years)
For scope of this question assume that ship itself is well built and it will indeed be able to carry people and material to its destination and technology wise, the mission will be success.
But what about the people? Some of the things about multi generational ships were talked in separate questions, but one I believe was not:
**What cultural norms would be the best for crime fighting?**
I have to admit something: I personally cannot understand what is so good on cultural norm of locking people away if they misbehaved. And I cannot understand it even more in setup where these 20 000 people are *locked away* in broader meaning of sense.
**Assumptions:**
1. Space travel is hard and things will get broken beyond point of repair-ability on the ship.
2. Society to build and send this ship is still scarcity society and people to board the ship commonly have idea "one thing is more valuable than another".
3. Given assumption 1, there might be times on the ship where *everyone* has to follow strict rules in order to survive the travel
4. Someone will misbehave in 600 years and break the rules.
I have come up with one solution to this which is completely away from current western world cultural mindset: Have everyone in generation 1 agree to be constantly watched and accept constant monitoring as cultural norm.
Also, I think that as of punishment, the system should be rather tough on people. I am actually toying with idea of human torture being culturally acceptable on the ship. Example: You steal something, we can see you. And because we did see you, we will cut off your hand as your punishment.
I personally do not like my original idea of the solution. Therefore I ask in this forum: How should the ship approach Law and Order on ship?
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**Torture is the last thing you should resort to.**
***Mutilation should never come into play.***
People can and will submit to quite a few rules in the interest of a certain goal, or ideal, however you're shooting yourself in the foot by mutilating your own crew.
**Initial Crew**
The original crew of your ship will have several things in common:
* They are trained professionals
* They understand the importance of their mission
* They all accept that they are making a decision with far reaching implications for themselves, and for their children
* They understand that whatever their lives were like on Earth, life on the ship will be nothing like it
In order to safeguard the success of the mission it's only natural that much stricter rules, procedures, and laws would be enforced than anyone had ever lived under before. These people will understand this.
However, the longer the mission drags on, and the more their situation sinks in, the more people might start misbehaving. After all, the first 19 generations are nothing more than caretakers meant to get the "bus" to its intended destination. It's their great-great-great-great-....-great grandchildren who will reap the rewards of their work.
And to that effect, some pretty heavy duty indoctrination, and manipulation will be necessary.
**Punishment**
Each and every person is a valuable asset on board your ship. They have specific training - they are not easily replaced. You have no pool of "spare" professionals from which to draw new crew members either - you have to wait for kids to grow up. Furthermore, that crew member will most likely mentor his/her replacement.
Locking people up because they lose their marbles and pose a danger to themselves and others should be perfectly acceptable. However, maiming that crew member, or killing him should be an absolutely last resort.
Instead, the focus should be on rehabilitating that crew member, with brainwashing, and other psychological manipulation being perfectly acceptable means of dealing with the psychoses which will invariably arise.
**Human Nature**
Frankly, I think you're pretty screwed as far as maintaining control of your crew is concerned. It's human nature to seek privacy, to buck authority, etc.
There will be places on the ship where people will build their own little unsupervised spaces. Where they will have hidden contraband, or meet to mate with someone other than their assigned partners, etc.
Teenagers will rebel against their assigned roles on the ship, and the injustice of having that future chosen for them.
Power-hungry ######## will try to over-throw the leadership and gain command & control of the mission (practically guaranteed to happen sooner or later).
Contraband will develop, with people who have access to the stores of supplies skimming off the top and trading it for various items or favors.
Additionally, you will also have to deal with Command crew members using their perks and privileges in illegitimate ways - such as detaining people they perceive to be their competition in some way (for their position, or for the attention of a mate, etc.)
**Maintaining Control**
You have to be able to monitor these people at all times. I would suggest implants, with a monitoring AI who acts as people' psychologist and conscience at all times.
This AI would not report all transgressions to Command ... only the serious ones, so that people would feel that they can trust and confide in it. The AI could also be a master manipulator, being able to either delay or confuse people when they have dark thoughts, or simply convince them that their course of action is not a good one.
The reason I advise such an approach is because a human crew cannot realistically monitor everyone's implant feed - you'd need more watchers than crew. Humans are also prone to corruption. But an AI, as long as it itself does not go nuts, is more or less the "deity" that generation after generation can look to for guidance and enlightenment.
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Well on a ship that will always have duties to be performed, locking people away in a cell seems to be counter productive. There are different kinds of trouble to worry about here. General crime, and social unrest.
**General Crime**
So work gangs. Those who break the 'law' get to do the crap work or dangerous work that needs to be done. If they refuse then you cut their rations. I also expect that much of the crimes would be rather petty, since in reality everything on the ship belongs to everyone else. Everyone needs to pull their weight in order to keep the ship running smooth, people fed and healthy, children educated etc. However, people do become jealous, and do have disagreements so physical altercations can happen, maybe even death or severe trauma.
In these cases, where work gangs might not be sufficient, they should be marked with a symbol, announcing their crimes to be socially shunned and watched much closer. In cases you get a true sociopath that is a danger to anyone, they need to be 'recycled' in order for them to help pay back the society they have damaged.
**Social Unrest**
This is more troublesome, since social unrest generally indicates there is a problem that is not being taken care of at some level. Is there just one or two people who loudly disagree with the current power structure? Or is it a deeper issue.
The obvious kooks can generally be ignored, since most people will find them entertaining or feel pity. Those who are really stirring up social unrest are another matter. In a small community (even 20000 isn't really that big) with limited resources and limited options, trying to make peace is the best option. However, humans have been trying for years to deal with strong ideological points of view with different measures with differing levels of success.
So the important part is to not alienate anyone group to a point it feels rebellion is even a reasonable threat. The best way is to keep people satisfied in their jobs and not have a very stratified society. The mission is a success or failure for EVERYONE on the ship and everyone should be working to make that success, and feel they are contributing to it as well. Meaning the best way to stop crimes are to reduce the reasons for them. People who are appreciated for their contributions are less likely to be discontent and cause problems. (teens will have to learn to get through that too).
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Despite some bumps and loops, the general global trend is to **condemn torture and the death penalty** as inhumane and therefore abolish both. It’s relatively safe to assume that this trajectory will not divert long-term, so it will be unthinkable for the society that launches the generation ship to implement a legal code that included such punishments.
That being said, in a rather small community of 20’000 people and effectively no communication with anyone else – i.e. it’s *not* like a small town, but like a planet with a tiny population – it’s not unlikely that eventually a mob will lynch someone or some charismatic power appeals enough to the lower instincts of people so revenge becomes acceptable once again and hence physically harmful or life-terminating sentences could be introduced in a later part of the long-term journey. That means, some achievements of a global human **civilization may regress** on a generation ship.
The **homicide rate** in the most developed countries currently is approximately 1 per 100’000 inhabitants per year (e.g. most of West and North Europe), globally it’s more than one order of magnitude higher. It tends to be less in oppressive systems with draconic measures and in rich states with working welfare system – roughly spoken. It also tends to be less in mostly closed societies where there is little conflict due to cultural differences and social inequalities. A single event can have extreme consequences, of course (e.g. the Oslo/Utøya attacks tripled the 2011 homicide rate in Norway). Unless something goes very wrong (as it tends to do in fiction), murder will probably be rare – less than a dozen per generation perhaps.
There are other crimes, of course, theft and fraud for instance. Depending on how members for the small society were initially selected and on how it works and deals with its limited, recycled resources, **some crimes are less likely** than others, especially during the first few generations. Greed and envy, for instance, will hardly motivate crime if everyone started with about the same level of wealth (i.e. relative worth of personal properties) and it was basically impossible to become comparatively rich (or poor). The ship-building society would probably also avoid sending people aboard who had a long or strong criminal record, especially in organized crime.
Imprisonment – in the sense of just locking away offenders – is a waste of resources and often neither improves individuals nor society.
Hopefully, **effective correctional methods** will have been developed in the meantime, but that’s probably only for notorious misbehavior.
You cannot effectively “rectify” people who committed a one-time felony in affect and you cannot punish them either because that serves no goal since it won’t scare others from doing the same in an extreme situation. The only thing that may work is when convicts voluntarily ask for forgiveness, receive it, and repay their debts (of whatever kind). Afterwards, they need to be accepted as respectable members of society again.
For the punishment / repayment of minor misdemeanors,
**exploit the constraints of the society**:
* There are dangerous, exhausting, unpleasant, low-prestige maintenance jobs to be done? – Thanks for volunteering by committing a crime.
* Human reproduction is strictly controlled? – The chance of your (and your already existing descendants’) sperm or eggs winning the fertilization lottery will plummet if you’re convicted, although if you (and your children etc.) work hard the probability may raise again.
* There’s no free market but automatically determined rations (and housing etc.)? – Guess who’ll not eat delicious Bief™ for a while.
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IMHO it may be counter productive to assume that cultural (and phenotypical/genetic) norms will still apply completely after we have had, say, 1000 years of space habitation - that's about 45 generations.
I am presuming one primary thing - we will not start sending ships until we've had many decades or centuries of people spending their entire lives in mostly or entirely self-sufficient 'floating' habitats - orbiting either a planetary body or in solar orbit.
Now imagine being born into such a habitat. For starters, the fact that you're alive is probably due to selective breeding, or at least approval of the fetus coming to term, with the full complement of genetic and epigenetic information available. Just as with many isolated island and mountain cultures, self-sufficient space habitats will almost certainly be forced to limit their population by some form of neonatal fitness test - usually this was in the form of a stress test, so if the infant did not survive the stress it would probably not have survived to adulthood anyway. An advanced culture could use more advanced methods than drowning for two minutes in an icy stream, and could optimize (even without full genetic engineering) for people who would fit into their small society and prosper and be productive in their domain.
As with some ranchers, it's quite possible that family strains that continued to produce unfit progeny would be allowed to die out without the right to bear children.
So you are an infant. With the cold vacuum of space only inches or feet away at all times, the opportunities for a child to cause not only their own death but the death of everyone aboard would abound - opening the wrong door, pushing the wrong button, an infinity of hazards would force the infant to become very aware, very early, of what not to do. Just as an infant learns very early not to touch the stove, you would learn probably before you could walk not to do anything that you don't *know* for a certainty is not dangerous - do not touch would have a life and death meaning.
At the same time you would be exposed and encourage to embrace a spirit of adventure and possibility, as the Universe is, indeed, "unlimited". So you would grow up being both bold and careful, and very used to living in close proximity with many others, sharing almost everything and depending on each other. If you didn't fit in, you'd probably have few choices, such as exchange with someone from another habitat (a good thing to do, to maintain genetic diversity).
So, after 40+ generations of this selective environment, folks that didn't fit into a space habitat would have been largely selected out of the gene pool. The biggest problem might well be too much similarity, rather than too much diversity. In other words, the problems you are worrying about will almost certainly have been dealt with centuries earlier, while these habitats were living in the Solar System.
My predicted scenario is this: A self-sufficient space habitat also requires some form of propulsion to assist it in station keeping and hazard avoidance, so it's already a form of space ship, albeit not much of one. Space habitats by that time might even be migrating around the Solar System. At some point, the inhabitants of one or more of these habitats will decide to 'head out'. Since they are already nearly or entirely self-sufficient except for things like nuclear fuel, it would not be a great leap for them to pack up and leave. And this would not be a significantly different lifestyle than they are already living.
The remaining piece is the ability to accelerate to a significant fraction of light speed (say 0.001c to 0.01c) - the difference between these is dramatic of course. If a habitat can accelerate to 0.01c by the time they are halfway to Alpha Centauri and similarly decelerate to arrival, their trip would be on the order of 1000 years. Conveniently, if the new star system has the essentials for nuclear power and a few other resources, they won't even necessarily need a habitable planet.
In conclusion, it seems to me that the need for extreme measures will have been bred out of the society for 500 years by the time the first ship leaves.
Of course, if there is some massive emergency that forces humanity into ships to get the hell out of Dodge before the Sun blows up, that's a different scenario.
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I don't think that cutting off people's hands is a good idea.
**Choosing The Original Crew**
When you choose the original crew, do it with care. Make sure you get people who will obey the law, and whose skills will be essential for the mission. Have people undergo a psychological analysis. Also, certain religions would be better for your ship. No offense meant to anyone, of course.
## Punishments
**Minor Crimes**
When people do something wrong, such as steal, or some other minor crime, I would do one of two things. The first would be torture, but not physical torture. Have some kind of chemical they inject you with, which causes extreme pain, but doesn't really harm you. The second would be supervised labor. After all, you need people to keep the ship going.
Minor crimes are pretty much anything that doesn't put the ship in serious danger, or seriously harm another person on the ship. (At least, on purpose.)
**Major Crimes**
Includes serious hints like sabotaging the ship, or murder. Only the unforgivable things. (Just look at the flowers, look at the flowers.)
Put the person in the airlock, then open it.
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## Enforcing The Law
It's a given that you will have police or authorities who will go around making sure the laws are being followed, but this won't stop all crime.
Have all areas under surveillance at all times. However, you must obtain a warrant to search people's rooms, effects, etc. You should also have to obtain a warrant for looking at tapes of people in the bathroom or look at the footage of them in their rooms. (We don't want creepers working with security.)
I also recommend everyone having ID cards. These cards would be scanned every time you opened a door, that way it is always known where you are. The doors would also scan people as they walked through, to make sure only one person was entering. So when you leave your room without using your ID card, then your door would give a sharp buzz and not open. It would be a serious crime to do things without your card. You would be detained until your intentions could be deciphered.
You would probably also need some kind of trial system, with a jury and a judge and all that. Like in the United States.
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*What cultural norms would be the best for crime fighting?*
You have to build upon what will be considered a crime and what will be considered misdemeanor.
The second category could be somewhat overlooked, with the most obvious cases punished lightly, most often with reparation penalty (the equivalent of repainting the wall you tagged).
The first category would be enforced harshly, with a culture that see those as an offence to all and that promote delation of such crimes. For example, in some country, not reporting child abuse is condemned as helping the abuser. Of course misdemeanor that get out of hand will be seen as crimes.
The goal is to provide a feeling of liberty around non-consequential things, even allowing a little thrill once in a while, while having a clear limit that one should not toe.
The punishment itself can range from social to psychological to physical. Removing someone from the crew has to be though of as removing a threat to everyone life.
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I think religion may be the answer here ironically. It has been used for at least 6000 years (more likely 500,000 years but let's be inclusive) as a means of controlling human behavior. Religion can be thought of as a set of rules, norms, and beliefs that are held as axiomatic. We don't argue axioms we select them.
In the same way, on a generation ship we don't argue about the mission or whether it is okay to steal, open airlock, or fart in close confinement. The crew needs to have an internalized sense of this a conviction of the rightness of what they are doing.
So the answer is a religious cult designed by thoughtful practical psychologists to be benign, stable and effective. You could call it a culture but is has to go very deep and the children have to be indoctrinated in it.
The rules should follow the Ostrom prescription they should be clear with graduated punishment and the possibility of forgiveness. You steal once you confess or are caught we instantly forgive you. It happens again we punish you and you have to work harder to get back into the good graces of the group. happens again we eat you.
So a religious cult is my prescription.
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With regards to long service and things getting broken beyond repair.
If you have the technology to build a ship big enough to travel through space for 600 years with 20,000 people onboard then you need to be a good ship designer.
If you are a good ship designer then you would design the ship so that all systems were serviceable on-board without the need of a space dock or "landing" and you would also provide all of the machines, technology, materials and machinery spaces to recreate any component on-board.
Extensive parts testing and parts commonality would help provide a mean time path to failure and simplify the need to produce 100,000's of individual components down to a few thousand. With this data in mind you can now stock the required materials plus contingency to accurately re-manufacture anything that gets broken or worn out.
Outside of a colossal disaster, recycling and good Preventative Maintenance practises would enable the ship to stay functional and fully maintained.
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user2757511 answer partly gets the point.
You have asked about **crime fighting**, but that does not only happen after the crime. In fact, it usually starts before the crime could happen. We are said by our parents and teachers what can be done and what can not.
So, the most important point of a Generation Ship is dealing with Growing and Educating newborns. You can see that in TV examples like Battlestar Galactica they had classrooms.
If your educate people such that crime does not reward, never, you'll have very very little number of big crimes (passional crimes will always be there), and for those you must be sure it does not reward. Use the airlock, after a fair trial, or forced labour, or whatever. Be sure to have a fair justice system. About minor offenses, just have an appropiate civil law system, but have them not to reward, never. If you steal one ration, you get condemned to half rations over a month.
Over all that, have a semi-military society where everybody has a job and a superior (except for the Commandant, who has the Mission Orders as a guide). Everybody knows what is expected from them, right from school. Everybody has a duty she can perform (because your job place is assigned from your qualifications on school, together with your desires) and which can be prod of, because your duty is fundamental for the survival of the whole ship. And get that idea instilled into people from the first years on nursery.
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Perhaps crime could be prevented by reducing the conditions that create it, and and minimizing their effects.
For example, financial crime could be eliminated by abolishing the concept of financial derivatives on the ship, with the exception of singular fees. Counterfeiting could be prevented by having no concept of physical currency, and using bio-metrically verified credit cards.
Sex crimes could be reduced by keeping prostitution legal and well paid, kind of like "the best little whorehouse in texas". A reasonable age of consent would help as well. Rape could be minimized by banning the ideologies that create it. Pornography would not only be legal, but government-subsidized, like non-pornographic media is in Canada.
Murder could be minimized by issuing industrial tranquilizer guns as the standard weapons aboard the ship, instead of modern firearms. Theft could be minimized by ensuring universal employment. With that, all theft would be for luxuries, rather than necessities.
Overall, it would be wise to restrict the laws to only ban things that are harmful to the population "and actually harmful, as opposed to religiously harmful"; and only require things that have actual uses, like electrical safety laws.
However, it's likely that crime will still happen. When this happens, I think the best model would be a hybrid of the Japanese prison system and the Norwegian prison system. "mostly Norwegian". In Norway's prisons, sentences are minimized, and the prisons are calibrated more for mental health and reform than punishment; with the caveat that the sentencing length is more of a matter of "you will be in prison until we determine you are no longer a threat to society". In Japan's prisons, it's routine to use prison labor for consumer electronics. This concept could be adapted for the ship, by giving the criminals the crap labor that nobody else wants. This handles how the guilty are handled.
Regarding law enforcement and criminal investigation, obviously a criminal/civil court will be needed on-board. Jury duty, as it is now, would be an annoying civic duty. The same goes for being a judge. Police and investigators would be under strict scrutiny, and corruption from these would have to be the most heavily sentenced crime, simply to avoid the problems plaguing police in the US, especially in small towns.
Basically, I think the best cultural norm regarding law and order is to go with what works: Don't ban what shouldn't be illegal, have laws when they're needed, have trials, have reasonable prison, don't use torture, and treat the problems that create crime.
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This is a test drive of the [alien-geometry](/questions/tagged/alien-geometry "show questions tagged 'alien-geometry'"). I hope it will be a fun tag.
Okay, for the purposes of this question, the world is flat (like, you still have plants and hills and stuff, just no long term curvature.) We don't care how far it goes, or why it like that.
So we have a world much like ours. We have sunlight during the day and moonlight at night. Plants and animals and such. The only difference is if you move 5 feet to East or West, you end up in the same place.
To visualize this, every object is visually repeated infinitely to the East and West every 5 feet. Of course, these are all the same object (they won't diverge or anything). You only viewing it from different angles. You can imagine sort of that the entire world is like a cylinder with a circumference of 5 feet (except that it isn't curved and the ground is still really deep.)
If we want to be precise, an infinity by infinity by 5 feet space, and [topologically glue](https://en.wikipedia.org/wiki/Quotient_space_(topology)#Examples) the two faces of this space together.
I hope to ask a lot of questions about this world, but to start off, let's look at combat.
* If I have something in my right hand, and I can put it into my left hand.
* I can arrange myself so the enemy is both directly to my right and left.
* I can fire projectiles far to the left or right (wrapping around the East-West dimension a couple times) to hit my opponent in the side.
How will combat be different? Both 1 on 1, and smallish battles (not thinking about big battles or wars yet.)
[Answer]
Its similar to fighting in a 5ft wide corridor of infinite length.
A defensive fighter would want to face opponent on a north south axis along the corridor. A large shield or two men standing abreast you block the entire world from getting past. Two attackers could charge forward with spears knowing their foes could never side step around them.
In a skirmish the vast majority of troops would be archers lobbing attacks over the handful of melee troops
It would seem that only a few dozen troops could participate in a war. The narrow confines also remove the traditional attackers advantage of choosing the site of battle, you don't need to defend a whole castle only 5ft of wall. Defense becomes much more effective.
[Answer]
1 on 1, you are in a world of complexity. Martial artists have an infinite edge over non-martial artists as they can appear to kick on the right side and hit the opponent on the left! Also there are very high chances a short range projectile weapon (like a slingshot) would be used by every combatant. The most shocking battles would ensue when the opponents face each other in east-west direction. Now you they not only have to defend themselves from the front, but the back too, as both parties can strike behind their backs and it will hit the opponent in their backs.
Generally in this world weapons like the [Meteor Hammer](https://en.wikipedia.org/wiki/Meteor_hammer) and the [Rope Dart](https://en.wikipedia.org/wiki/Rope_dart) would have far higher effectiveness against fixed-shape weapons like the sword, spear, mace etc. Battles where two masters fight, one with a fix-shape weapon (sword) and the other with a rope-dart would be immensely complex, both to write and to comprehend.
In battles involving projectiles, every trooper would be trained rigorously about how to hit the opponent on both sides while standing right in front of him at much distance.
Detailed analysis of weapons and combat tactics depends on what level of technology the residents of this universe have, as compared to ours.
[Answer]
Would a being evolved in such a space really even perceive the duplicate images, or would their wetware evolve to eliminate the cognitive overload of the redundancy? Perhaps they would only perceive a single instance of each object, albeit viewed simultaneously from many angles. Perhaps their perceptions would convert the flat space around them into a perceived cylinder, to give them awareness of the wraparound effects?
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