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Imagine a group of people with an "invisibility" power that make them unnoticed and immediately forgotten by everyone. This power would be a mix of the [witches spell](http://hdm.wikia.com/wiki/Witch) in "His Dark Materials" and the powers of the [Silence](https://en.wikipedia.org/wiki/Silence_(Doctor_Who)) from Dr Who, not a true invisibility (like Susan Storm and the invisible man have). Otherwise they're normal humans.
This power is hereditary, and activates during puberty. Once activated it cannot be switched off or otherwise controlled. Invisible people can't ever go back to being normal and will remain "invisible" **at all times** for the rest of their lives.
However, other supernatural creatures can see them. They often hunt them for their skin and bones, and use these to make "invisibility" amulets and clothes that grant the wearer a bit of their power.
Invisible mothers often abandon their babies, so that they can have a normal childhood and be safe from the hunters. They grow up in foster families or orphanages and once their power activates, everyone they ever met forget about them and every paper and photograph proving their existence become blank.
I've thought about making the invisible people forge alliances with other creatures and have them raise their children. The problem is I don't see anything better than the invisibility amulets they could offer in exchange for protection.
The invisible people tend to move around a lot. They travel fast, since they can enter any ship or boat they want. Because of that, they may give birth in every country of the world.
They can see each other once their power activates, but they have difficulties to communicate using computers, letters or phones because any recording of their faces or voices glitches a lot and tend to fade away, and their writing disappears in a few minutes.
I'd like them to share common traditions and cultural traits, and form a social network together, but it's hard to build a common culture in this setting.
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**My questions are about the social and cultural impact of their power:**
How can they have a common culture in these conditions? What kind of traditions would they develop?
Does the "drop the baby" strategy sounds coherent? How would they choose where to give birth?
In the mixed-race packs/families scenario: What could they offer to other supernatural creatures to be accepted as part of their group, without fear of being killed and skinned?
Is there any other cultural/social/psychological consequences of their power I forgot?
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**Money**
As a community they are going to be rich, really really rich.
They can walk into any bank vault and walk out with the contents or any penthouse and walk out with the jewlery. They can be the perfect assassins and spies. Their services will be invaluable as long as they remain secret and forgotten. They could walk up to the president in a meeting and sprinkle poison in his coffee without having to change out of their bath robe in the morning because they were sleeping beside his bed and using the presidents bathroom that morning.
What could they offer other supernaturals? Mortal cash. Lots of it and anything which that can buy. They could also offer security. A vampire might like having a bodyguard who can walk up the Slayer and snap an explosive collar around her neck while being ignored or a spy who can sit in on the Vatican's super-secret anti-vampire "lets bless the water reservoirs and pacific ocean" summit.
**Communication with mortals**
They have difficulty communicating with normal people and using their money since their recordings and writing disappear. I see 2 options here. Recruit a superstitious human willing to believe that the writing that appears in front of them then fades is messages from god. Have him transcribe your instructions into writing that does not fade as it appears and mail it to the appropriate legal firms. Give him "gifts from god" etc to keep him in good condition and cooperative.
Actually you'll probably want a number of people like this but I suspect they wouldn't be hard to find.
Your invisible now have legal entities under their control. They can send written instructions to legal firms representing them who are paid in cash and gold.
Alternatively recruit some of the supernatural beings to act as their agents in exchange for mortal wealth and/or amulets etc from the elderly dead. Again the other beings can interact with the human world on their behalf and take dictation.
**Factions**
If there's a lot of them there's likely to be clans or factions of invisibles who will want to remain secret from each other as well.
Some are going to be richer than others, some might employ different strategies to defend themselves.
Some might defend themselves through obscurity, leading quiet lives while others are going to have their own teams of hired ex-marines hunting any vampires, witches or djinns that come sniffing too close.
**Childcare**
If you're richer than Bill gates with a load of puppet corporations under your command you're not going to leave your children to the foster system. They're going to have trust funds for their care as if they were orphaned children of billionaires and since you're invisible you can check in on them and make sure they're being cared for well. Even if their parents are not rich some of these kids are going to feel like they have some kind of guardian angel looking out for them because in reality mom saw the bully make them cry and made sure something awful happened to the bully.
Finding out you're not actually an orphan and that mom and dad were really close by the while time, that the occasional feeling like someone was hugging you when you were sad was actually real the whole time is going to be a very common shared experience among them.
**Medical care**
Giving birth might actually be a problem. If none of the staff on the maternity ward can see you they can't really help you. You could die halfway through childbirth while the medical staff ignore you. They're going to need their own staff of invisibles with medical training to give birth.
Actually that brings up another issue. They can learn anything that can be learned from a book but if they want or need any skill/craft that requires training from masters/craftsmen who can interact with them to teach then they're going to have to learn the skill at a young age. Expect bright 11 year olds to find themselves pushed into medical/nursing/ob-gyn training by order of distant guardians or the conditions of some trust fund so that when they finally turn invisible they're already trained enough that they can help the clan/family.
Care for their incapacitated or sick may also be a problem. If you're invisible crossing the street becomes far more dangerous and if you're hit people will keep walking past you ignoring your cries for help. If the clan has any structure for caring for their sick it's going to need to be staffed with their own kind. Secret hospital wards filled with invisible people and invisible staff. A mortal nurse/doctor would have trouble feeding and caring for patients they are incapable of perceiving and/or remembering exist.
They're going to need a significant shared culture simply because they're going to have to rely on each other for a lot of things.
**Internal service economy**
It doesn't stop at medical care. Any services that invisibles want that require interaction with another attentive human are going to require other invisibles to do it. Need a haircut? good luck with a mortal hairdresser. Want your nails done? the person doing it needs to be able to see your nails. Massage? Ditto. Therapist who can actually hear you and remember what you say? Need an invisible.
So even if a lot of them are spies or assassins others will make a good living providing "human" services internally.
**Secrecy**
They're likely to have traditions of enhancing their secrecy with fronts and double bluffs. It is after all their most effective defense.
If they have to worry about vampires.Some are going to have front individuals. It's easier to live inside a fortress with guards and anti-vampire defenses if everyone believes the crazy billionaire is a paranoid recluse (but visible mortal) loner rather than the family of 4 who actually live in his 20 room suite with him.
Anyone who does know about them who has need to defend against them will probably have pressure sensitive floor tiles etc to defend against a knife in the back. This includes the invisible's themselves if they have any competing clans or conflicts. Indeed some of the more powerful people in the world might try to recruit them as their own bodyguards. An invisible bodyguard who can see invisible assassins is useful.
**Communication with each other**
They're likely to have face-to-face meetings or summits or to communicate through any medium that doesn't fade. If Carved stone doesn't fade they can use that, if damage they do to living beings doesn't fade they can communicate through a writing system based on vegetables with scalpels stuck into them in patterns. It's very hard to have all forms of communication fade unless all their effects on the world also fade.
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> How can they have a common culture in these conditions? What kind of traditions would they develop?
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I suspect this would be a group of loners, or small group dynamics. I think it would be very unlikely to be one continuous culture across the globe.
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> Does the "drop the baby" strategy sounds coherent? How would they choose where to give birth?
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Actually the 'drop the baby' at a nice home almost has to happen, how would an invisible mother raise an infant? a baby floating through the air as it is breast fed... On top of that you said people forget them, so how would the child remember their mother? A bigger issue is, how does the mother get pregnant? Do they only have sex with others of their own kind? or do they act as a succubus or ghostly intercourse with men in their sleep?
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> In the mixed-race packs/families scenario: What could they offer to other supernatural creatures to be accepted as part of their group, without fear of being killed and skinned?
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Invisible people have the ability to be the best intelligence officers in the world. they can collect information, and as we all know information is power. This would allow them to be very powerful indeed.
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> Is there any other cultural/social/psychological consequences of their power I forgot?
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I think it would be easy to fall into either a need for power being fairly powerless when people forget you and not have an 'identity' or trying to force yourself on others consciousness by turning into a 'poltergeist'. Moving stuff around, pinching people, making noises etc.
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I would expect that such a race would wipe out humanity in very little time long before they had a chance to realize how useful the slave labor force could be. They would have instant access to free food, which would then deprive the humans of food. Over time, the humans would tend to starve and die out. Likewise for water sources or any other consumable.
Presumably this would extend to any other animal. After the humans are extinct, they'd have to hunt for food themselves, but that's easy since nothing bothers to run away. Because nothing ever fights back, they would quickly dominate the planet, reproduce like crazy, and eat the entire world's food supply before going extinct themselves now that there's no food to support a population that size.
If the mutations leading to their memory power didn't occur until long after society started forming, they would be more likely to control their power. Still, people are notoriously bad at using their brains when life seems good. The early ones would have done major damage to their ecosystem thinking they're invincible, then there would have likely been a giant, unseen war while the smart ones reined in the party types.
Since then, they would have to develop a pretty strict code of conduct to keep the humans (or at least *some* food/water supply) alive, much like the [Masquerade](http://whitewolf.wikia.com/wiki/Masquerade_%28VTM%29). They would likely keep their population size low to make out-of-control members from doing any major damage.
Another thought to consider: In any real world, people would *have* to notice these guys because of their effects on the planet if they had any major population size. It would be hard to quantify them, but we would end up doing tighter and tighter experiments on them, and eventually would discover the secret.
Now, you're adding other non-human, "supernatural" beings, who I presume have tons of other weird powers and so forth. In this case, it could very well end up being the other supernaturals who keep the invisibles in check. Vampires certainly wouldn't be happy if the invisibles killed off their food supply.
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I could imagine that at least one common **tradition** would be celebrating the day their power activate by exchanging stories of how they found out or how it happens to each!
An other **tradition** could be exchanging stories of how they could escape from a hunter and the commemoration of friends who have been catched/killed maybe even a kind of feast day!
But these traditions would mean they have some kind of community and possibilities to communicate.
The story of **drop the baby** is plausible, but how could they choose where to leave them? Do they know or do they have the ability to know who is a hunter or not?
As a **consequence** maybe they would have a kind of secret life as if they have a partner who has not the power to become invisible this would end up with many Problems as they might ask them where they have been etc. I guess such relationships won't be easy.
**What could they offer**? Hm i guess they could be good spy's and messengers for delicate information and stuff
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So, I read on the net the other day that one method of delivering water while terraforming Venus (this is assuming the problems of day length and sun exposure are sorted out) is to bombard the planet with hydrogen which reacts with the co2 atmosphere to produce water and graphite.
The article I read this on suggested using hydrogen from Jupiter, but in my project Jupiter has already been claimed by another state looking to terraform Ganymede, so the Venus terraformers use a Bussard ramjet field to “harvest” hydrogen from the atmosphere of the sun, where it is then delivered to Venus. The problem of getting the ramjet close enough to the sun is, I figured, not an issue since it can be placed at a distance and the electromagnetic field is extended for the rest of the way.
Is this plausible? I can’t find a problem with it myself, but I want to be sure.
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**In 1971, MIT students at the World Science Fiction Convention roamed the halls chanting, "The Ringworld is Unstable!" Larry Niven fixed the problem using Bussard Ramjets along the rim of the Ringworld. O'course, that wouldn't work, either...**
*And that's why you should ignore everyone and stop seeking confidence to use a perfectly good suspension-of-disbelief solution.*
If you ask a group of engineers or scientists whether or not a sci-fi idea is plausible, you will always be given sheets of paper explaining how it can't be done.
* During the 1990s when I was working as an Electrical Engineer designing one-micron geometry BiCMOS circuits it wasn't just believed that nanometer MOSFET geometries were impossible — *we knew it.* Why do I have trouble with the phrase, "follow the science!"? Because I've lived long enough to know it's not that trustworthy. 1990s science *knew* that nanometer geometries were impossible. [Until 2016](https://www.theverge.com/circuitbreaker/2016/10/6/13187820/one-nanometer-transistor-berkeley-lab-moores-law) when researchers at the Lawrence Berkeley National Laboratory created the world's first 1nm gate.
**Conclusion**
*I love your idea.* It has scientific backing in the form of using hydrogen (regardless of its source) to create water on Venus. Your story can't use Jupiter, which is a honking long way away anyway! A ring of Bussard Ramjet platforms casting a series of hydrogen streams past Mercury and into the path of Venus' orbit is ***uber cool!***
Use the information you read on this Stack to load your story with interesting facts, but don't rely on any of it to tell you wat *not* to do. Write that story, dude. If Larry Niven can use Bussard Ramjets to stabilize the Ringworld (way, way, way too far away from the sun!) then *you* can use them to bring water to Venus.
*Cool idea!*
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No. This is absolutely not practical. The solar wind is far too low density to be useful on this scale.
The solar wind is [round-about](https://en.wikipedia.org/wiki/Solar_wind) $7.5 \times 10^{12}$ particles per square meter per second at the Earth's orbit. And a little less than twice that at Venus's orbit.
The atomsphere of Venus is 92 Atm. pressure and 96.5% CO2. This means about 1450 moles/m$^3$, roughly $8.6 \times 10^{25}$ molecules per m$^3$.
It means that each square meter of your collector requires about 184 thousand years to convert 1 cubic meter of atmosphere at surface level. A collector with the same diameter as Venus would require (since the area of a sphere is 4 times the area of its cross section) 3/4 million years to convert the bottom meter of the atmosphere of Venus. Assuming you could get 100% efficiency.
And as a reality check, note that Venus has been there for about the same time as the rest of the solar system, some 5-ish billions of years. And the solar wind has been spraying on Venus that whole time. And Venus is still jam-packed with CO2.
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Looked up how close could we get to the sun; The Space shuttle reinforced carbon-carbon heat shield is designed to withstand temperatures of up to 4,700°, if the shield wrapped the entire shuttle, it could fly within 1.3 million miles of the sun. Venus is 107 million miles from the Sun. Surely getting 82 times closer would change this calculation; based on surface area enclosed at 1.3M miles and 107M miles, hydrogen concentration should be ~942 thousand x greater at 1.3M. Assuming it can be transported, instead of 3/4 million years, you'd be looking at about 10 months, not 750,000 years.
And that is with existing materials, used on the Space Shuttle. If you take some minor liberties with future shielding technology, you could probably get the Ram jets much closer to the Sun.
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**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
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You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49).
Closed 3 years ago.
[Improve this question](/posts/191565/edit)
So our protagonist city-state is a decently sized, rich in resources, and populated(think 100 thousand people) kingdom with Early Medieval Dark Ages technology(no gunpowder or cannons). The attacker has about the same amount of resources, but a whole ten times the population, and now they want to conquer our city-state. Their technology is roughly equivalent to that of the late iron age, and they can mobilize a 100 thousand strong invasion force. Assuming that the entire city state can mobilize maybe 25 thousand people to work for the state, and there are 12 months to prepare for the invasion, what would be the best way to prevent the attackers from overrunning the city-state? No magic, and there are no defenses currently in place.
Edit: The territory of our city-state is roughly 1600 square kilometers, around 40 by 40 kilometers, and have basically all the resources you can ask for. Describe both the defense preparations and the battle itself.
Tactical And Strategic Info:[](https://i.stack.imgur.com/1ZBdz.png)
Our city-state's forces: 10 thousand regular troops, 50% infantry, 20% archers, 30% calvary
Equipment: What you would expect from the crusades
The invasion force: 100 thousand troops, 99% infantry, 1% archers
Equipment: What rome had during the early republic
Goal: Prevent the invasion force from getting inside the city, make the force retreat or kill all of them.
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> "Amateurs talk about tactics, but professionals study logistics."
> ~ Gen. Robert H. Barrow
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The keys to victory here will be buying time and cutting supplies.
You will want to begin by building a decent city wall. Most classical cities used them because very few were actually good at siegecraft. While the Romans eventually got okay at it, most walled cities were simply considered unassailable or otherwise tooks over a year of siege to capture. Instead most battles were actually fought over farmland and other resources that laid outside of the city.
Furthermore, the river means you can make a flooded moat around the wall which would prevent any method of Roman era siege craft that would allow for a quick storming of your city. Your relatively large number of archers also means that it would be very difficult for the attackers to fill it in to make a land bridge over which to bring ladders or a siege tower. So, if the attackers want your city, they will need to starve you out of it.
Knowing when the enemy is attacking 12 months in advance is also a HUGE tactical advantage here. That gives you time to plan your crops and growing seasons to harvest all of your food just before the enemy arrives and bring it into the city just ahead of the attack. This will prevent the invaders from feeding off of your land, and maximize how long you can stay in your city. And, don't just hoard food. You will need to stockpile firewood, medicine, arrows, and clean water too.
Classical armies this size needed a lot of food which often had to be captured from the defender's farmlands, or the campaign would fail. Long supply lines coupled with large armies have been the bane of many classical era generals. Once the attacking army realizes that there are no local farmlands to exploit, they will likely be forced to disband a large portion of their troops and rely on wagon train to bring in all of the food to supply their army which will be very expensive for the invaders and ultimately unsustainable.
This is where your cavalry becomes extra important. Inside of the city horses are useless, but before the attack you can break them into many smaller skirmishing regiments and have them sneak around the attacking army. You can position them at intervals along the supply lines of the attacking army. Because the invaders have no cavalry to counter them, your horsemen can hit-and-run the supply wagons with immunity. Find a small convoy, just hit it. See a bigger one, ride ahead to merge with other regiments until you have enough men to take it.
The horse raiders will steal what they can to keep themselves provisioned and burn the rest.
Even if the attackers try to adapt by breaking off a massive force to defend the supplies, you generally can not march long distances in full battle formations; so, such caravans will naturally form long columns in many places which would be vulnerable to hit and run maneuvers where your cavalry could ride in, burn the supplies, and ride off before the infantry can mount a proper defense.
While the defenders might have enough food for a year or more rationed away in anticipation of this battle, the attackers will be out of supplies within weeks. The attackers will be forced to retreat all the way home having never been able to force a single pitched battle with the smaller defending army... or if they wait too long to realise how truly screwed they are, they will be forced to surrender giving the smaller state a massive supply of captured weapons and armor and the ability to ransom the army back to the attacking nation at a price that would prevent them from funding a follow up invasion for years to come.
All this said, perhaps you still fail to cut their supply lines; so, it is good to have a Plan B. Since the defenders had enough time to store a bunch of drinkable water anyway, they do not need the river for its water. So, just before the siege begins you could also dump a few carts of dung into the river upstream of yourself. The attackers will not expect the water upstream of your city to be contaminated; so, on top of starvation, you can also make them sick. If you make the attackers sick enough, they will not be in good enough of health to fight or retreat; so, this too could make it easy to force their surrender.
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First I would build a city wall, the best that could be made depending on local materials. Ideally stone, but there might not be enough time or materials for that, failing that mud brick, Earth and timber or a combination. A substantial fortification of some form would be very doable within a year including a wide deep ditch.
Second ensure that everything edible within the approach corridor of the invading army has been removed or destroyed along with as much wood as possible.
Third ensure the city is fully provisioned that there a huge amount of arrows are available and the citizens are gainfully employed in harvest, construction or other military preparation such as training as militia.
Fourth position the vast bulk of the cavalry out of the city (with supplies) and as soon as the enemy are detected send a signal to activate the cavalry force.
When the cavalry force is signaled to attack they move out in a very in a wide arc well out to one side of the attackers and the overrun the enemy supply train from behind kill or capture the horses and burn the wagons. They then move forward enmass and attack the enemy from behind causing a great deal of chaos.
The defenders in the city should be able to hold out against initial attacks with stout fortifications and a vast superiority in archers.
The cavalry retreat before any serious resistance can be mounted and disappear over the horizon. Scouts watch what the enemy is doing and large scale raids are made on the enemy at night on an adhoc basis. After some time the enemy would be worn down, starved and dispirited and likely to withdraw. Prisoners could be set free with stories that encouraged defection.
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If it comes down to similarly-equipped-mass-vs-mass fighting, then the small city has already lost.
* Give the small city a small technological advantage. Steel swords against bronze. Bigger horses or faster horses or better armor. Trebuches vs catapults, etc. Under the right conditions (usually involving surprise), that small advantage can make an enormous difference.
* Use diplomacy and intrigue effectively to sap the enemy's strength before the invasion begins. Promote the Emperor's rivals so he's afraid to leave the palace and lead the invasion in person. Get efficient generals replaced by buffoons...or venals who can be bribed. Plant rumors of alliances and other deceptions to shift the invasion plan into the wrong season, or before the invading army is ready. Encourage a second army of merchants, camp-followers, crooks, and others to accompany the invasion force, slowing it down and distracting the leadership.
* Use chemical and biological warfare in depth: Poison all of the water supplies that the invaders must use on their route of march and for their siege. Put your plague-carriers and other infectious into uniform and send them out as "scouts" to be captured by the invaders as they cross the border.
* Use natural, artificial, and imaginary (deception) obstacles to slow the advance, cut off supplies, and protect rear-area ambush forces. The poisons and sicknesses need time to be effective. Try to slow their advance to just a few miles per day. Flood roads and fords, set avalanches and rockslides in the passes, burn the fields and forests -- all timed to divide up their forces and scramble their units and communications. Those rear-area ambush forces should target small, high-value targets - like message runners.
* As the advance bogs down, agents in the palace should deceive the Emperor into anger at the remaining competent officers, and get them replaced with buffoons, too. Encourage the Emperor to set impossible, unachievable goals that will dismay his minions and soldiers slogging along the road. You want to encourage tens of thousands of desertions, first hiding among the camp followers, then scampering back towards home each night.
By the time the invaders arrive at the city, they have already been through an ordeal. You want them to arrive weeks later than they expected, exhausted, sick, starving, badly led, disgruntled, and at half-strength. A hollow force.
The combination of 1) The hollow invasion force, 2) The city's extra-strong wall, 3) The city's well-fed, well-led, well-equipped, high-morale defenders, and 4) The secret-weapon at the critical moment will combine to enable their much-smaller force to scythe through the attackers to victory.
...oh, and remember to bribe the attacking general to launch un-coordinated and un-supported attacks to waste much of their numerical advantage, to change the plan mid-battle, and to generally cause chaos within the attacker's ranks. The bribe may cost a lot, but it's worthwhile.
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**The best defense is a good offense.**
I conclude these are not warlike people in this area, if the city as it stands has no defenses but is next door to a (newly!) aggressive neighbor. Aggressive neighbor has apparently never been a threat until now. Maybe they are not good at it. I am betting that if you have no defenses your neighbor does not either.
Your aggressor has only infantry which means they will attack by land, on foot, so they cannot be that far away.
You have 3000 cavalrymen. They can cover the distance fast, before your enemy knows it is under attack. Use them to attack the capital of your enemy. Your foot soldiers will be right behind coming as quick as they can. Take the capitol and the leaders there who have decided on this warlike course of action.
Treat the citizenry kindly! Do not sack the city! You need these people on your side!
Then make clear to the people of your neighboring country that their leaders are idiots. Display captured leaders in clown suits. Your two countries have always been good peaceful neighbors and you like it that way. Fighting is wasteful and stupid. Put in a government in your neighboring country that feels that way. Maybe whatever government these new bozos kicked out - bring back the exiled prince. He will be grateful!
Take the siege engines and armaments from the neighboring city and burn them in a big pile.
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Go to work on a freaking wall for your city when you get back, already!
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The other comments have laid out what the defenders should do to a T ( I especially like Nosajimiki's logistics-based answer). Basically the attackers in this scenario are the ones with the harder task. Taking a walled city in antiquity (or even modern-day without artillery) is HARD. Logistics in the ancient world was even harder. So what I will attempt to do is a frame change describing the attacker's best-chance strategy given the situation you described.
1: Their angle of direct attack (overland from the northeast per your drawing) is hugely sub-optimal. The defenders have superior numbers of horse, and a year to both stockpile supplies and strip the area. The tyranny of supply means you'd be tied to oxen-pulled supply carts that quickly end up carrying more food for the oxen than supplies for your army. (for more details check out [THIS](https://acoup.blog/2019/10/06/new-acquisitions-how-fast-do-armies-move/) lovely explanation.) Yeah it might be shortest "as the crow flies" but you may well starve to death before you get there and will certainly have a hard time supplying your forces overland for a siege. Instead if possible they should march up the river, preferably from a point in their own or allied territory. This will allow you to transport your supplies much easier, even if it is upriver. It'll also allow you to bring more supplies, and they'll be better protected from enemy raiders. (instead of a literally miles-long wagon train you can transport the same amount of supplies on 1-2 barges, allowing you to concentrate your defense.)
So we've got your army there. Sure it might take a little longer going around rather than straight at the city, but this way is MUCH safer, and now your men are \*less likely to starve to death! Huzzah!
2: Time to attack. We're going to set out during the low-water period of the year, whatever that happens to be. The dry season, high summer, whenever. The main thing is to have as little flow in that river as possible. If the river is huge (talking Amazon/Mississippi) then the traditional "start of campaign season" will have to do.
3: How to take a walled city with a Legion. Well let's assume that the city is well-stocked (they had a year to horde grain and time their harvests) and obviously they have plenty of water because of the river. Heck, they probably have a moat in addition to a wall, which makes it essentially impossible to breach via the tech level the army has available. But the river can also be a weakness. I'm not sure how wide your river is, but there are a few options.
Option A: Dam the river. The hardest-but-surest option. Depending on flood plains, available knowledge base, and available supplies (can they get boats from upstream? Are there nearby forests?) you could just block most or all of the river's flow into the city. As a city built on a river they are highly unlikely to have wells, large cisterns, or other sources of water. You can't starve them out, but you can thirst them out!
B: Plague them out. Your army intentionally spoils the river flowing into the city. Use it as a latrine, dump offal into it, whatever nastiness you can think of. Not going to work if the River is the size of the Amazon, Nile, or Mississippi, but if it's something small there's a chance you could befoul the river enough that those inside catch something horrible. Walls are worthless without soldiers to defend them! You can also build catapults/ballista to lob the traditional carcasses into the city, but I don't know if your attackers are technologically sophisticated enough for that.
C: Coup de main. They've got tons of supplies, good walls, probably a moat, and plenty of trained men. But (given your description of medieval army vs roman-esque army) our infantry should be both better trained and better equipped. Barring some sort of spycraft/traitor inside to open a gate, the best way in is going to be from the up-river gate. Launch infantry assaults along both sides of the up-river gate with a rock-laden barge to slam into the gate itself. With luck the gates break and a riverine assault can begin. If they don't break perhaps (though we're stretching a bit now) assaulting troops could attempt to scale the wall from the barge itself. This however is a long shot. Really if "cut off their water supplies" or "give them cholera/typhoid/plague" doesn't work, there's really not a lot the attackers can do but settle in for a multi-year siege and hope their supply lasts longer than the defender's supply. Or at least lasts long enough for someone in the city to get greedy/desperate enough to open a path from the inside.
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The setting is a city enclosed within a safe boundary that protects it from a magical blight. This blight kills all animals outside the boundary when the sun is down. Farmers live inside this boundary, and travel outside to their farms during the day, returning before the sun sets.
While I imagine some parts of the ecosystem can adapt to this, such as birds, it poses problems for localised parts of the ecosystem that do not have the capability for large daily migration patterns, such as worms and other creatures that improve soil quality, which prompted this question.
Restraints:
* The demand for a safe place to sleep means that land inside the boundary is at a premium. Simply farming inside the boundary is not practical when there are large swathes of unused land outside the boundary.
* 'Animals' does not include plants, or micro-organisms. The plants live on at night, as does bacteria and the like.
* Technology level is the standard medieval-ish level.
* Magic exists, but for all intents and purposes is unaccessible to the farmers.
* Climate is undetermined at the moment, if required it can be whatever suits your answer.
With that in mind I'm wondering:
* Is it even possible for this to be viable farmland?
* If it is possible, what crops are best suited to these conditions? (ie. ones that don't need to be pollinated by insects, ones that are best suited to low soil quality)
* If it isn't possible, are there adaptions the farmers could make to make it viable? (extra fertiliser? Portable insect farms? Does leaving the fields to fallow have no effect if there is no life in the soil refreshing it?)
* As a bonus, how many hours a day would be needed to work the land to produce crops under these conditions? (This restricts the amount of farmland is available, since a farmer has to be able to walk out to the field, work, and return to safety during daylight hours)
[Answer]
When this magical blight first appears, it will be incredibly disruptive to the biosphere, and if it happens suddenly (in evolutionary time, ie less than hundreds or thousands of years) there will be mass extinctions both of animal species which don't reside in the safe zone, and plant species which rely on such animals for pollination.
Assuming that this construct has been in existence for enough time to stabilise (or the humans did some *very* speedy ecological engineering!), there will be a hierarchy of land surrounding the safe zone. The land closest to the boundary will be by far the most productive, because it can be fertilised by animals grazed out during the day and herded in at night; and pollinated by bee hives maintained within the safe zone. It will also be the land which can be most intensively farmed because it requires less commuting time for farm workers. There will be intensive competition between arable and pastoral farming in these areas, but since the greatest range that pollinators like bees will travel [seems to be](https://en.wikipedia.org/wiki/Forage_(honey_bee)) about 5km it would make most sense to grow arable crops in this immediate vicinity, with wind-fertilised grass pastures beyond for animals that are herded in each night, out to the limit of what land can be accessed in time.
A human can walk at about 5 km/h, so the absolute maximum radius for this 'tillable zone' is about 41km; but fields this far out would only be accessible for an hour a day for one month of the year, hardly intensive farming. The furthest a field could be from the boundary to still be reachable throughout the year would be 9km.
Farming, especially using medieval technology, was a very time-intensive occupation, with farmers labouring from before sunrise until after sunset every day. This would be inevitably curtailed by the 'curfew', but the intensity of farming would be reduced as a result.
In the UK we get around 4,380 hours of daylight in total per year, distributed cyclically which we can naively model as:
$$Y\_0 = \int\limits\_{0}^{365}{4.5 \ sin(\frac{2 \pi x}{365} + 12}) dx = 4380$$
If we equally naively assume that the yield of a piece of farm land is directly proportional to the number of hours spent working it, and that medieval farmers will work every daylight hour they can, then the yield of a piece of land at distance $R$ from the boundary is:
$$Y(R) = \int\limits\_{0}^{365} \max \left( 0, 4.5 \ sin \left( \frac{2 \pi x}{365} + 12 - 2 \frac{R}{5} \right) \right) dx $$
Which you can see [here](https://www.wolframalpha.com/input/?i=plot+z+%3D+max%280%2C+4.5+*+sin%282+pi+x+%2F+365%29+%2B+12+-+y%2F2.5%29+from+0+%3C+x+%3C+365%2C++0+%3C+y+%3C+50) plotted from the spring equinox. The flat red area is the zone unreachable at that time of the year.
Assuming that the boundary is circular with radius $r\_0$, then the total yield of the annulus of reachable land around the boundary is:
$$Y = \int\limits\_{r=r\_0}^{\infty} \int\limits\_{\theta=0}^{2\pi} r \int\limits\_{0}^{365} \max \left( 0, 4.5 \ sin \left( \frac{2 \pi x}{365} + 12 - \frac{r}{2.5} \right) \right) dx\ d\theta\ dr $$
Wolfram Alpha will helpfully solve this crazy integral, and gives me that $Y$ out to a distance of 20km (comfortably the 'zone of influence' of a medieval village) is about 55% of the 'normal' level of working (where farmers are distributed across the land such that they don't have to commute). Out to 40km (the point where the infected land becomes basically unreachable) the overall workability falls to less than 23%; but within the 5km 'pollination zone' the workability is about 88%.
In short, the farming yield of a village in this situation would be reduced by (at least) somewhere between 15% and 50%, with some alterations needed in distributions of farm types. On a purely logistical level, this isn't complete deal-breaker for the survival of the settlement.
Of course there are lots of other reasons why an isolated medieval settlement like this is not viable, of whatever size; external resources like metals and fuel will be quickly exhausted: timber in particular will be an extremely dangerous commodity to harvest, as lumberjacks will need to travel far to the retreating forests and then return with heavy loads as the sun sinks ominously. But you asked specifically about farming, and from a logistical standpoint at least, it's not impossible.
[Answer]
Some ideas:
* Only animals bigger than a certain size or mass die. Small animals like earthworms or insects survive because they are too small for the magical blight. Plants may survive because their cell structure is different to the cell structure of animals. (The magical blight is some kind of radiation)
* Only warm blooded animals die. Very small animals are ectotherm, so they don't attract the magical blight. Plants are obviously cold, too. (The magical blight is some kind of bacteria)
* Only animals with lungs die. Insects, earthworms and plants don't have lungs (The magical blight leads to a massive reduction of oxygen in the atmosphere)
* Animals which sleep under the surface of earth survive. (The magical blight is some kind of radiation)
* Only animals with a certain brain size die. The magical blight might be some visuals or sounds that drive people and animals crazy, so they die from a heart-attack.
Most of those ideas would lead to the same farming conditions that existed in the real medieval.
[Answer]
All the obvious answers have been provided so I'll throw in one from left-field:
## Burrowing animals caught above-ground fertilise the plants.
The flora on this planet have adapted to the huge abundance of nutrients provided by animals dying in their vicinity. In this way, they have evolved barbs for stopping burrowing animals from escaping beneath the surface to escape the magical blight. This has examples in real life in the proto-carnivorous plant "Puya Chilensis" (sheep-eater plant) which gets sheep tangled in its barbs, resulting in them starving to death and rotting next to the plant, providing biomass to the soil. These plants are cultivated by humans as well, as they are useful for making fishing nets.
[Answer]
Dead animals are processed to make fertilizers for the plants. Smaller ones are left to decay. Larger animals are either harvested for meat when freshly dead or processed to make fertilizer or fodder ingredients. Leaving large dead animals is not sanitary and may spread diseases.
Beehives may be relocated to the safe areas so that the bees return to their hives before sunset. The path of bees is fairly predictable as they return to their hives before sunset. Other pollinators are not.
Size limit was not specified, but saying that microorganisms can survive means there is a size limit *somewhere*. Are earthworms and pollinators safe? The boundary limit is not specified: How *deep* the blight effect goes under the soil level? I assume there is a limit here. Is it effective to build animal shelters underground, or under a mound? So, **set your own size and depth limit**.
In order to be able to meet work deadlines, the farmers will divide their field into two plots: the one nearer to safety will be dedicated to the labor-intensive crops: those that need lots of attention, mainly vegetables. Further out, those that are in a less need for intensive care, mainly fruit trees.
[Answer]
[Hydroponic farms](https://en.wikipedia.org/wiki/Hydroponics)
The basics of hydroponics are very simple: instead of soil your plants grow with their roots hanging in nutrient-rich water.
With some effort this is achievable with medieval technology. No animals required.
Some questions:
**But how much food can you produce this way**
Enough to moderately feed a small population, the Netherlands is one of the largest producers of food [in the world](https://www.nationalgeographic.com/magazine/2017/09/holland-agriculture-sustainable-farming/) mainly due to this method.
**But there won't be pollination!**
true, no pears then, but there are [plenty](https://youshouldgrow.com/self-pollinating-plants/) of self-pollinating plants or plants not grown for their fruit
**Where do you get your nutrients?**
Humans and their livestock do this thing called "pooping". turning this into hydroponics-suitable nutrient slurry would be part of the "some effort" part of my answer.
[Answer]
>
> ones that are best suited to low soil quality.
>
>
>
Firstly, the fact that the soil will be accumulating dead animals already makes it rich in amino acids. Deamination of these amino acids that leads to ammonification provides a nitrogen rich environment in the soil. After nitrifying bacteria have converted ammonia into nitrogen that is useable by the plants. Rice paddies (depending on the location), lettuce, cabbage, rhubarb, brussel sprouts, kale, mustard greens, beans, etc. all require a sufficient amount of nitrogen for prolific growth.
>
> As a bonus, how many hours a day would be needed to work the land to produce crops under these conditions?
>
>
>
The presence of organic matter *(cellulose, lignin and pectin from dead plants; proteins from dead animals; chitin from skeleton of insects; polysaccharides from cell walls of fungi and other microorganisms; and finally urine and faeces)* in soil leads to the phenomenon of humus. Insoluble humus to be exact - consists of unrecognized parent material of organic matter, residues of microbial decomposition of plants (that will eventually die) and animals.
Insoluble humus:
1. Improves soil structure
2. Facilitates slow release of nutrients
3. Increases water holding capacity of soil
Humid material makes up 10% of soil weight, thus, tilling might not be required for insoluble humus.
Soluble humus provides the nutrients the insoluble will facilitate slow release of.
Work for farmers - providing urea (urine or faeces (hey, recycle that waste)).
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[Question]
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Would potato- or grain-like crops be able to flourish in northern alpine regions? There's a lot to be said about the Andeans, but the have the benefit of living near the equator that other civilizations do not
Considerations:
- 8-12 thousand feet elevation
- Steep, primarily granite mountains
- Highlands climate
- 78 to 48 F in the summers
- 45 to 15 F in the winters
- 36-40 degrees North (on an Earth map)
- late medieval technology level (but not necessarily the time period)
[Answer]
**Qingke**
The best analogue of your nation is actually Tibet. The Tibetan plateau sits some 4.5kms above sea level, and they have crops up there which look reasonably similar to those in lower altitudes, but with some differences.
The most common crop in Tibet is something called [qingke](http://factsanddetails.com/china/cat6/sub37/item1693.html), which is a form of barley that grows particularly well in high altitudes and is both cold and drought resistant. But, they also grow wheat, rice, potatoes and the like. If you look at their farming practices in the same link, even on the side of mountains they tend to terrace their land, putting specific crops on different terraces for the season. I'm assuming that they would rotate crops between terraces for the health of the soil but I couldn't find that information in the link.
Based on my readings, barley is a common crop for high altitude and mountainous terrains, largely because of its hardiness. BUT, it's important to note that (IIRC) it has less than a third of the energy value of wheat, meaning you need to grow more of it to get the same value in terms of energy. I don't know offhand about the nutritional values but it would appear that barley related foods are a primary staple for Tibetan farmers so it certainly has to have at least some nutritional value in that regard other than energy.
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The Incas grew many varieties of potatoes on the Andes mountains of what is now Peru. They also grew quinoa, squash, beans, and a species of corn that is different from the modern. I would expect also that any spring crop like spinach, beets, and peas would do well in a cool environment. They used terraced gardens to compensate for the lack of flat arable ground.
[Answer]
Mind you, there's a key element beyond elevation, and that's *location*. Agriculture in Tibet and on the Altiplano is possible because they're close to the equator. Whereas in New England (where I'm from), treeline in the White Mountains goes under 4000 feet in areas. The alpine tundra's notoriously fragile -- footsteps can disrupt vegetation for many years -- and I wouldn't wager on cultivation to support just about any population in such a zone.
[Answer]
It depends.
You would have the fields in the valleys, not directly on the mountain sides. In the southern parts of the mountains you could grow more crops than in the northern parts. The part of the mountains where it rains a lot are worse than the sunny parts.
I found a nice article about farming in the Alps in German here: <https://www.planet-wissen.de/natur/gebirge/der_mensch_in_den_alpen/pwielandwirtschaftindenalpen100.html>
It is divided into the Romanesque Alps and the Germanic Alps, here are two parts translated with DeepL:
>
> The Romanesque mountain farmer's economy
>
>
> In the High Middle Ages,
> agriculture perfected itself in the form of the staggered economy. The
> alpine areas are vertically divided into different height levels,
> which enables the farmers to use the terraces differently throughout
> the year. The yields of the individual levels must be combined in such
> a way that a family can make a living from them. The valleys are
> preferably used for growing cereals, while the higher altitudes are
> used for grazing livestock.
>
>
> Strictly speaking, Alpine agriculture must be divided into Romanesque
> and Germanic regions. In Romanesque mountain farming, which can be
> found mainly in the Southern Alps, agriculture and dairy farming are
> of equal importance. The farmers use the sunny areas as arable land,
> while the meadows are replaced by the shady locations at higher
> altitudes. The arable land and fertilised meadows are privately owned,
> the alpine pastures and the forest are there for everyone.
>
>
>
[...]
>
> Germanic mountain farming
>
>
> On the humid northern edge of the Alps and
> in the Eastern Alps, cereal cultivation is so unfavourable that
> livestock farming dominates in Germanic mountain farming. The
> landscape of the Northern Alps therefore lacks arable terraces. The
> farmers use the arable land only for two to three years to cultivate
> cereals, after which they are green again.
>
>
>
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[Question]
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Kikazaru and Protogon have been fierce rivals in the designer baby industry/artificial wombs since time and memorial, but Kikazaru is looking to finally best its rival by introducing a new scheme: designing babies so same sex couples (biologically speaking since identity makes this a bit murky) can have a child of 'their' own.
Is it possible to engineer a embryo with genes of both partners (selected either by choice or selected by rng)? Would it be possible for say both two males, females, or would this service only be able to be provided to one such pairing? What issues might Kikazaru possibly run into with this scheme?
Ex: would chromosomes be an issue in any way or would it simply be: the child is going to be this sex without special intervention.
Note:
While Kikazaru has experience in editing genes to change genotypes for things like: eye color, hair, general characteristics, etc. This (in my mind) would be uncharted territory.
They also have experience with gene editing to combat hereditary diseases if that could possibly be an issue (I'd be interested to hear if it would be).
[Answer]
# It would definitely be possible for male-male couples. Female-female couples are much more challenging.
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Here are the embryo generation procedures for same-sex couples (the embryos afterwards are either implanted in the womb of one of the parents, a surrogate, or an artificial gestator):
## Male-Male Couple → Male or female child:
This one is easy, since there's an X chromosome, a Y chromosome and plenty of sperm. I never want to type those last three words again.
Both parents provide sperm, which is centrifuged and separated by weight (the X chromosome is heavier than Y). An X sperm has its nucleus removed and inserted into an [enucleated egg cell](https://en.wikipedia.org/wiki/Somatic_cell_nuclear_transfer), which is then fertilized with an X or Y sperm from the other parent (they can choose or leave it to chance).
Alternatively, you could use stem cell technology to program a man's germ cells to produce eggs. The DNA is produced the same way for eggs and sperm, so men have all the necessary hardware to, with a little tweaking, produce viable human egg cells.
## Female-Female Couple → Female child:
The egg cell is comparatively easy to get, just take one from the ovary surgically. The sperm cell is a different story. Unlike in the case of the male-male couple, we can't necessarily replace the nucleus of the sperm cell with the nucleus of a female egg cell. The problem is that the nucleus of an egg cell is several times larger than the sperm cell. It would be like trying to put an egg into a grape: surgically impossible.
Also, sperm cells are really fragile. When you have 1 egg and a million sperm cells, the egg has to be really durable, but it doesn't matter if a sperm cell malfunctions. Sperm cells often have defects like 2 tails or 2 heads, both of which prevent the sperm from reaching the egg. Unfortunately for Kikazaru, this means that trying to replace the nucleus of a sperm cell (a process that involves putting a huge hole in the cell membrane) will probably make the sperm non-viable.
We also can't get the woman to produce sperm by manipulating cell specialization, because the woman's germ cells (the cells that produce eggs and sperm) become inactive after birth, so adult women can't produce new eggs at all, let alone sperm.
To get around this, we would have to remove the DNA from the female and directly put it into the sperm cell. It can't be from any cell in the mother – otherwise the child would be half-cloned from the mother. The DNA has to be taken from the germline, after recombination (the process that shuffles the DNA from 46 chromosomes to produce the 23 that go into the egg or sperm). Typically, to get DNA from a cell intact, we would find cells in [metaphase](https://en.wikipedia.org/wiki/Metaphase), when the DNA is grouped into neat chromosomes (with chromosomes, you can count how many there are under the microscope to make sure you have them all). But female human germ cells turn into eggs before birth, and stop dividing – they never enter metaphase.
So you have to take the germline DNA in interphase, when it's grouped into a structure called chromatin, which is loose, tangled and messy. It also tends to fill the space it's given, so it will be the same size as the egg nucleus. So you would grab all of the DNA, then squeeze it into the sperm, trying not to make it explode in the process. This is super messy, so you'd have to repeat it over and over, and women have a limited amount of egg cells, so you'd have a good chance of rendering the woman infertile while failing to produce a child.
A possible solution would be [Artificial Gene Synthesis](https://en.wikipedia.org/wiki/Artificial_gene_synthesis), also known as DNA printing. This technique allows researchers to synthesize DNA strands of any sequence they want. Currently this works by creating random DNA until the right sequence is found, so it takes longer the larger the DNA you want to create. In the future, though, we might be able to produce entire human genomes in the lab (I'm guessing Kikazaru and Protogon already can do this as part of the designer baby process).
The lab would sequence the mother's DNA (read all of the genes) and then reprint them into a germ cell donated from a man, which would then recombine the chromosomes and develop into 4 sperm cells by meiosis. Then, one of the sperm would be sucked into a pipette and forcibly shoved at the egg, which it would hopefully fertilize (if it doesn't, rinse and repeat).
## Female-Female Couple → Male child:
Same challenges as above, with the addition of the Y chromosome problem. To make a boy, you need a Y chromosome. A same-sex female couple has 4 X chromosomes between them. To get this to work, you'd need a male Y chromosome donor, so a small part of the child's DNA would come from a third 'parent.' Luckily, Y chromosomes aren't really that important. Their DNA consists of 'Be a dude' + a few random genes, including the gene for hairy ears (for some reason). So the DNA of a healthy, hairless-eared male would be sequenced and would replace the X chromosome in the Artificial Gene Synthesis process described above.
## Bonus: Babies with more than two polyamorous parents!
If we're running everything through sequencing and gene synthesis, we can just treat DNA as data. This means that you could have a child with yourself, using an algorithm that finds the healthiest recombination of your own DNA to avoid inbreeding (like cloning with a little bonus shuffling). You could have a kid with 10 other people, where you each contribute a couple of chromosomes, and the algorithm does the rest.
## And much, much more!
You could have a child with a dead historical figure whose genes have been extracted from their hair, or with a celebrity. There would be crowds of people trying to get DNA samples of famous people to sell on the DNA black market. Give birth to a baby clone of Tom Cruise for just $5000!
Who said anything about human-only DNA? Make your baby able to photosynthesize! Make them digest cellulose! Have permanently blue hair! Take your pick.
Yeah, designer babies are pretty freaky. Once you have the tech to make a male child of female parents, you can totally play god with humans.
[Answer]
In principle one could devise the following way of working:
* take the reproductory cell from partner A
* take the reproductory cell from partner B
* if neither A or B is an egg, take an egg from a donor C, or create a synthetic one
* join genetic material from A and B (in C if needed) and stimulate fusion
However, in humans females are carriers of XX chromosomes, while males are XY. So, when you pair two males you have the possibility of pairing a YY embryo, which is non vital. Therefore you need to find a way to filter X from Y, or accept a higher mortality rate in male-male couples.
[Answer]
With two males you could take the X chromosome from one and mix with the Y chromosome of the other to give a baby boy OR you could take both X chromosomes to make a baby girl.
(Note, as this is being done artificially, you wouldn't create a YY)
With two females however, there is no Y chromosome to make a male embryo, so you would have to work out some other way of engineering that Y chromosome which isn't possible with current real world science (eg modifying an X into a Y or transfer an X into existing Y chromosome would delve into SF).
This is assuming you've already sorted some way to create an egg/embryo from just chromosomes (ie you can graft the DNA into an existing fertilised egg, or create an unfertilised egg plus sperm with specific mRNA(?))
[Answer]
**Chimera!**
<https://www.scientificamerican.com/article/3-human-chimeras-that-already-exist/>
>
> One way that chimeras can happen naturally in humans is that a fetus
> can absorb its twin. This can occur with fraternal twins, if one
> embryo dies very early in pregnancy, and some of its cells are
> "absorbed" by the other twin. The remaining fetus will have two sets
> of cells, its own original set, plus the one from its twin.
>
>
>
This is simple compared to trying to make a baby out of 2 sperm or trying to make meiosis obey your commands.
1: Make a somatic clone of each partner.
2: Then at an early stage in development, merge the cells.
The resulting embryo will be a mix of the two partners, just as one type of chimera is a mix of two twins.
Bonus 1: This sidesteps recessive genes issues and the possibility that a child of two parents who are both heterozygotes might be homozygous for a detrimental recessive.
Bonus 2: There is no reason offspring made in this way might not be made of 3 or more individuals, all contributing cells and genes to the final chimera.
Downside: The chimera's own gametes will be those of only one contributing "parent", not a mix of them all.
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[Question]
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Our AI in question inhabits a synthetic brain housed in an organic and genetically modified human body (With a few other cybernetics). This body/brain combination was the result of a black project aimed to create super-soldiers (Why is it always super-soldiers?), and every synthetic brain produced as part of that project was populated with an actual brain. Synthetic brains are also used to treat certain brain disorders, but are incredibly expensive and with medical technology, generally not needed. The ones used by the black project are of a different make, of course, but largely indistinguishable. You can't have a secret operation if one scan your subject reveals they're really not human.
Now, we have an AI that inhabits one of these bodies. They are, however, given false memories, and their emotional/logical/etc programming is on par with what a human would think. Of course, they think better, clearer, faster than a human - But that can be attributed to the black project modifications.
The AI is aware that they were part of this black project, but are led to believe they are like the other "participants" in the project - Enhanced humans, for the most part. A few clones. A few genetically modified clones.
AI in general are rare, but known of. They typically occupy government and military positions, although a handful are useful to large corporations. The power of these AI is, of course, linked to the physical size of their processing unit(s). Think of a modern server farm - Sure, you CAN process stuff on your desktop, but running it in a server farm is much, much better.
Similarly, AI at a smaller scale is capable, but it isn't absurdly better than an actual human. For that you require large constructs. So, a human-sized AI wouldn't be extremely better than a human - Of course, they'd be good at math and logic, but there are people who have been ridiculously good and fast at those.
The AI believes they are "human" - But are given some form of argument that convinces them they *might* not be what they think they are. **How would they go about proving they are (or aren't) an AI?**
I realize a lot of what I've said seems to be in the vein of making them impossible to detect - But this is not the intent. It is simply there to restrict the AI to a degree that they could reasonably believe they are human - And so would others. Differences are detectable, with great effort.
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If your AI is built on a different substrate (silicon rather than flesh), it would have different response characteristics to physical stimuli. Alcohol, caffeine, psychotropics -- it might *emulate* those responses in order to create a better human simulacra, but that emulation might be flawed enough to be noticeable by the AI. In particular, I think the very-rapid human response to adrenaline might be something where even your generally-faster AI might realize "Hey, it's not just that I 'hold my liquor well' and don't get addicted to heroin, I just don't jump at horror movies the same way."
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There is only one possible route; which I will describe below, but otherwise your conditions make the task impossible; unless "largely indistinguishable" means "difficult but not impossible" to distinguish. If they are smarter than humans and think they are human, then they think most humans are pretty stupid, and that anybody telling them they are non-human is just mistaken, and mistaking their clear fast *biological* thinking for something other-worldly. Because stupid humans are prone to attributing things they don't understand to magical or supernatural causes. Hence, religion and creation stories.
And in fact the word "genius" derives from the word "genii", just a few thousand years ago people attributed high intelligence to supernatural spirits giving the answers to great inventors and original thinkers --- Heck we still do it today, watch the show Ancient Aliens and they can't believe Einstein, Newton, Tesla and others could possibly be just humans solving problems, they had to be getting their ideas from telepathic extraterrestrials!
Without some tangible proof, you might as well try to convince an atheist that God exists. And that is what your question is asking, how do I convince a very smart and clear thinking human, that believes they are a human, and is indistinguishable from a human, that they are not human?
There is, therefore, only one way: The subject must be shown the black project and how all of that worked and why the changes are indistinguishable, along with some proof it was implemented and such AI are extant. Presuming the subject is smart enough to comprehend all of that, **then** you might be able to get him to the position of *maybe* he is an AI. But, he would also think, *any* smart person, including entirely human ones, would have to harbor some doubt, so it isn't a certainty at all.
[Answer]
* As suggested in a comment, the Blade Runner universe might serve as an inspiration. AIs in that universe are also indistinguishable from humans at first glance and are often unaware that they are AIs. But their thought processes have some subtle differences which can be exposed by monitoring the subject's body reaction while giving them a complex psychological test.
* Considering that the black project's goal was to create super-soldiers, it might have be a sensible idea to program the synthetic AI brains with some memetic backdoors to ensure better control. Maybe there is some code word, image or other mental stimuli to make the AIs obedient and have them execute any order given to them. Demonstrating this would be a good way to prove that they are AIs.
* Other than that, you could do some brain surgery. Open their skull and take a look at their brain. A synthetic AI brain will likely look far different than a biological one when seen up close.
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**If they go to see a neurologist saying they don't know whether they are human being, would they be refereed to psychiatrist or to software engineer?**
;)
What would be a result of running through a standard set of neurological tests? Would they have a normal EEG? Do they have a normal neurochemistry? Are there any standard test for discovering synthetic brain? (or exactly its model) Lumbar puncture? (or what is used in that era?)
Because for me standard seeing doctor could be the way to go. Actually the officially stated reason could not be "Am I an AI?" but trying to solve some minor problem (like annoying headaches) or just feel a bit different (like those untypical talents and just claiming to want they want to be sure they are all right).
[Answer]
**This task is exceedingly difficult, yet possible**
If your Super-Soldier AI needs convincing of something, there are ways, but they are quite ethically troubling, and possibly not what you want.
Any attempts to talk a person out of basic, lifelong held assumptions about their existence through logic is going to end in failure.
If your AI thinks like a Human, remember Humans care a huge amount about their reputation. From an evolutionary stand-point, brains exist for two very closely related reasons:
1. Surviving long enough to reproduce
2. Reproducing
critical thinking is not necessary in all situations, just some. Working together in a community that contains the opposite sex is so beneficial that critical thinking is less important. Bad relations with all others is really really bad news.
So, what you need is:
* A charismatic leader, who knows the true nature of the AI
* Some way for the AI to join the group of the charismatic leader
* A period of isolation from anyone not in the group
* Ideally, a way to make it seem to the AI that everyone they care about thinks they are an AI, or a way to make it seem like everyone in the group knows this
This is how Totalitarian regimes and cults are successful. They've managed to convince people of things much more outlandish than the fact that someone is an AI. (think Jonestown massacre, Nazi Germany etc). A really good example of this is the Asch experiment, which I would recommend looking up
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I just detected a strange object in space, and it appears to be of alien origin! Telescope readings seem to indicate it is some sort of deep space probe, with a golden disk of some sort attached to it. It appears to have some engravings on it, and grooves around the edge, but it's a bit fuzzy. As luck would have it, it's headed straight for our system, and will likely collide with our planet!
We have access to about present-day-earth level tech. We are obviously very curious about this object, and would like to land it safely to inspect it, or, barring that, redirect it into a safe orbit around our planet or at least get some close up pics or something. What's the best we can do? How much warning could we get to prepare? If recovery is impossible with our current level of tech, how advanced do we have to be to pull this off?
To clarify, I am an alien in a distant solar system, and Voyager 1 is heading *towards* me, and my goal is to recover or at least get a close look at it.
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As other users have mentioned, it's going to be very,very unlikely that earth-level tech would be able to ramp-up *in time to catch it* - though the rocket is technically feasible, it's a bit of a stretch to assume that the scientists would be able to:
1. Actually see the probe with their telescopes (the probe is very, very small - it took over 80 years to find Pluto!)
2. Settle academic debate on what the probe is - remember, at a distance it will just be a speck of light indistinguishable from a perfectly mundane asteroid. The only chance for very early detection is that a very lucky radio signal (let's say the probe's been sent spinning, so the high-gain antenna is no longer pointed directly at earth, and its pings get picked up as a peculiarly regular signal by a radio observatory)
3. Get funding for this *tremendously expensive* mission
4. Build, test and launch the rocket
all within the launch window - including the time taken to match the speed of the probe, which will be a long time if you're using ion propulsion.
My suggestion: **Treat it like Pluto**
Intercepting a fast object is hard, but it's much, much cheaper to do a flyby - build a New Horizons-style probe, launch it with a number of very high resolution cameras and spectrometers and put it on a course to fly by and record as much information about the probe as possible.
E.g. to actually rendezvous with the probe:
[](https://i.stack.imgur.com/oB5rc.jpg)
but to simply fly by and take pictures, you only need to match the position:
[](https://i.stack.imgur.com/cuhZb.jpg)
With some luck (and some very fast cameras), scientists would plausibly be able to reconstruct the details of the golden plate (probably not enough to read the record grooves, however), but they would be able to determine the chemical composition and mechanical construction of the probe, determine that it was launched with chemical rockets by looking at chemical emission spectra and verify that it bears alien pictures and was not launched from their own planet (though the debate around that point might be an interesting subplot).
Without launching anything at all, they could get a pretty good estimate of where the probe came from (based on telescope trajectory measurements).
Voyager would also bear characteristic marks from deep space - miniscule holes from micrometeorites, possible a large missing chunk from a not-so-micro meteorite and (maybe) some residual charge from its trip through interstellar plasma.
(Note that these measurements can't be taken from the surface of Kerbin - no terrestrial telescope on the ground or in space has enough resolving power without being very close to Voyager.)
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* Get everything into orbit. The Apollo missions to the Moon launched the crew and lander on one rocket. It might be possible to launch what follows next in one step, but perhaps it needs to be assembled from multiple launches.
* Decide: manned or unmanned? Given the nature of the mission, do you want a remotely-controlled craft? Or do you want people?
* The expedition needs to match course with the incoming probe. That might involve traveling out towards the probe, then turning around and going on a parallel course. You will need lots and lots of [delta-V](https://en.wikipedia.org/wiki/Delta-v).
* Capture. It probably involves a quarantine, to avoid damaging evidence. Is there "alien" DNA left on the probe? Fingerprints? Germs?
* Turn around and go into orbit of the homeworld. More delta-V.
* Decide if you can bring it down safely, or if it stays in a space station.
The required [delta-V budget](https://en.wikipedia.org/wiki/Delta-v_budget) could be very high -- the [speed](https://commons.wikimedia.org/wiki/File:Voyager_2_velocity_vs_distance_from_sun.svg) of Voyager **relative to the sun** isn't the same as the speed of Voyager relative to the alien homeworld.
As mentioned by [JDługosz](https://worldbuilding.stackexchange.com/questions/78766/how-do-i-recover-a-voyageur-1-probe/78774#78774), you will need lots and lots of delta-V. That means the spacecraft will be optimized for long-range travel, not an atmosphere-capable launch/landing system. Think of some of the Mars proposals, or [similar designs](https://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket).
Timing might throw a spanner into the works, however. If they waste a decade building the perfect craft for the mission, the alien probe will have passed. Perhaps the best bet is to re-purpose an [Asteroid mission](https://en.wikipedia.org/wiki/Human_mission_to_an_asteroid) that happened to be almost ready to launch. Dump most of the science payload, take extra fuel, and there you go. Worry about quarantine when the mission comes back.
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The xkcd *What if?* article on [*an unmanned mission to retrieve Voyager I?*](https://what-if.xkcd.com/38/) covers this — a rendezvous would amount to the same thing.
So, using conventional rocket technology to go to a body moving at high speed relative to us, and return with it, would be very expensive and impractical, though technically *possible* (assuming nations could still afford it).
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Recovery of the probe would be extremely difficult, but you can *slow it down* so that it just misses your planet and hopefully slingshots into an orbit that allows you additional opportunities to slow it down until you can capture it.
1. Hit it with a laser. This will not only push it (slowing it) via radiation pressure, but it will also ablate the surface of the probe, causing it to slow down as it ejects mass. Hopefully the etchings on the surface are not just a molecule thick :)
2. Put a thin cloud of hydrogen in its path, so it slows down via friction. You have to be careful not to heat the probe up too much.
3. Get a ship to rendezvous with the probe (as it orbits your system) and build an aerobraking shell around it, or attach a laser sail to it. Then you can be more aggressive in slowing down the probe. This has the advantage that your ship only has to meet the probe, not slow it down, and you can slow it down without having to impact the probe itself (via laser or friction slowing). A solar sail, especially if it can be deployed and retracted, would allow for radiation pressure from the sun to slow/accelerate the probe as needed when it is too far from your base laser, so you can constantly be modifying the probes trajectory into more favorable ones for you.
If you start while the probe is far enough away, even a tiny change in velocity will make it miss your planet, then it can slingshot behind the planet and start to slow down. The goal is to put it in an orbit that brings it close to your planet again, so you can keep slowing it and letting it be slowed via your planets gravity. Eventually it will be slow enough you can try to aerobrake it in your atmosphere and retrieve it before it hits the ground or it will have a delta v low enough you can get a ship on a matching course (probably via some long orbit with lots of velocity building slingshots of its own) with enough remass left to slow it to a lagrange point or stable orbit where you can study it at your leisure. This will take a LONG time, probably decades.
Obviously you can take all the pictures you want as it passes, though you well have to get clever with positioning to capture all sides, unless the probe is spinning (or you make it spin with your laser).
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**Possible without any really *new* technology, but no existing or 'off the shelf' *spacecraft* could do this. You'd need lots of warning to design, build, and launch one.**
You'd need to send a second probe to rendezvous with it, grab it and push it out of an interstellar trajectory to an orbit around the planet.
This would require a lot of delta-v capacity (at least several tens of kilometers per second; [as of January 2015 Voyager 1's speed relative to Earth was 27.2 km/s](http://voyager.jpl.nasa.gov/mission/weekly-reports/) - if it passed through another solar system, this would vary based on the velocity of that star relative to the Sun and the orbital velocity of the planet around the star) - far, far too much for a practical chemical rocket. So you'd want ion engines. NASA's current NSTAR ion engine has a specific impulse over 3000 seconds, and the currently-in-development NEXT (supposed to be ready in 2019 [according to Wikipedia](https://en.wikipedia.org/wiki/NEXT_(ion_thruster)) will be over 4000. So you could do this with a mass ratio probably in the ballpark of 2.5 - 4.
The problem is that ion engines are power hungry and have low thrust, so you'll need to run the engines for a long time. The probe will probably fly by the sun and leave the high-solar-power area too quickly (though solar panels are getting pretty advanced, so maybe...) Your best bet would be a nuclear reactor - this is possible within current technology, but would require a long lead time and political will to overcome the concerns about launching nuclear materials. I don't know enough but it ought to be achievable in well under a decade *given sufficient funding and political will* (it was only ~8 years from Alan Shepard's suborbital flight to Neil Armstrong's moon landing, and that required genuinely new developments).
If you already had nuclear-powered ion-engine space tugs in space, the lead time could be much less.
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> As luck would have it, it's headed straight for our system, and will
> likely collide with our planet!
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This should simplify things. First a quick stat. Voyager 1 is traveling at ~3.5AU per year (roughly the distance from jupiter to mars). That should help establish a timeline for all this. I know the other answers say that it would be almost impossible to see the probe at any real distance, but your question didn't ask if it could be found, but what to do after it is found. So I'll leave it up to you to have it get found with enough time to do something about it.
To recover the probe, you'll need a [space-pusher](https://en.wikipedia.org/wiki/Pusher_(boat)). Since Voyager 1 is coming straight at you, the trick will be to nudge it into an orbital pattern instead of a crash landing.
So build a space-pusher, launch it, get it going around the same speed at Voyager (~1.5 time the speed of a space shuttle), and slowly push it to the side. There is the chance you'll end up slingshotting it instead, in which case you get to nuge it again. Maybe it'll take a few years and several orbits around various planetary and stellar bodies to get to to finally settle into a stable orbit, but once that happens, you'll be able to examine it at your leisure.
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Pathogen virus work in a simple way: they inoculate their genes (DNA or RNA) in the host cells and let them replicate huge amounts of the attacker while hampering the host vital functions. As reaction the host fights back, until either the host or the guest is dead.
I am trying to figure out a "smart" virus, which only inoculates its genes and does no alteration of the host metabolism.
It targets any cell, but has a predilection for the gonad cells, so that whenever the host mates will also transfer the virus to the offspring. Bonus of this scenario is that the offspring will see the virus as "self", so won't even try to defeat it.
Is this a realistic scenario or am I neglecting something?
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What you propose is totally reasonable virus strategy and happens all the time. Your description of a stormy viral infection is one edge of a spectrum. Chronic stable viral infections, heritable viruses partly integrated into the genome, and ancient viral fragments all exist. This paper calls ancient viral fragments in the host genome "viral fossils" which I think is cool.
<https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3205384/>
A fine example of what you are looking for is hepatitis B. Hundreds of millions of people carry hepatitis B. Many of them are infected at birth from their mothers, and themselves carry the virus lifelong, infecting their own progeny. @PatJ here writes infected cells must die to release virus but this is not true: cells can shed virus and go about their business. Just as I am certain that my sinonasal epithelium is at this moment shedding virus for my coworkers to inhale yet that epithelium is not dying; I would notice the bloody slough coming out my nose.
From <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC98986/> Hepatitis B biology.
*One of the reasons for chronic HBV infections is that the virus causes chronic, noncytocidal infections of hepatocytes, the principal cell type of the liver. Hepatocytes continuously shed virus into the bloodstream, ensuring that 100% of the hepatocyte population is infected.*
Cell and virus have many, many types of coexistence. Viruses are the oldest parasite.
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# Use Adenovirus
[Gene therapy](https://en.wikipedia.org/wiki/Gene_therapy) can use Adenovirus as a vector to modify a cell's DNA.
[](https://i.stack.imgur.com/J5UAU.jpg)
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> In order to replicate, viruses introduce their genetic material into the host cell, tricking the host's cellular machinery into using it as blueprints for viral proteins. Scientists exploit this by substituting a virus's genetic material with therapeutic DNA. (The term 'DNA' may be an oversimplification, as some viruses contain RNA, and gene therapy could take this form as well.) A number of viruses have been used for human gene therapy, including retrovirus, adenovirus, lentivirus, herpes simplex, vaccinia and adeno-associated virus.[3] Like the genetic material (DNA or RNA) in viruses, therapeutic DNA can be designed to simply serve as a temporary blueprint that is degraded naturally or (at least theoretically) to enter the host's genome, becoming a permanent part of the host's DNA in infected cells.
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It wouldn't be outside the realms of science to target the adenovirus at a particular cell type (viruses do this anyway).
How you modify the recipient cell's DNA is up to you and your research team.
So, your theory is totally legit.
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There are a few little problem.
First, inoculating its gene (and having the cell using them) is in itself a modification of the cell's metabolism. It can be a very minor one, but it's always a modification.
In order to be released and to continue expansion, the virus needs the infected cell to die. Because the new viruses are within the cell, the usual way for them to get out is to over-produce viruses until the cell dies, releasing all the newly-made death machines (note: death machine is not a biological term as far as I know).
If you want your virus to truly be "mild", you'll need it to find a way to escape the cell. It is possible, though it would require a more complex virus. The more complex, the more improbable.
So I would say "not likely, but possible".
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My understanding of these issues is cursory at best, but you might be interested in [endogenous retroviruses](https://en.wikipedia.org/wiki/Endogenous_retrovirus#Human_endogenous_retroviruses). I cringe when I try to explain this because I am by no means a biologist, but my understanding is that viral infections in our ancestors could permanently transfer genetic material into our DNA which was then passed down the generations in the usual way. The Wikipedia page I linked claims these ERVs comprise some 5-8% of the entire human genome. They're often non-coding (i.e. no known function); I guess they might arise when a viral sequence mutates in such a way that it's no longer pathogenic, but the sequence is nevertheless still there and still propagated by cell replication.
In fact, one of the ways we can see when our evolutionary path diverged from that of various other animals is by seeing which parasitic viral sequences we have in common with them, which must have arisen from infections of our common ancestors.
We've even observed what's called [horizontal gene transfer](https://en.wikipedia.org/wiki/Horizontal_gene_transfer) (much more common in single-celled organisms, but relatively recently demonstrated in multicellular life too), where a virus can pick up a fragment of one species' genetic sequence and deposit it in the sequence of another.
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**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
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You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49).
Closed 6 years ago.
[Improve this question](/posts/68694/edit)
### Plot.
I made a pact with a demonic being: I wanted to be a successful sportsman in any team sport.
Why I wanted this stupid wish to be granted? Because I'm a fatty un-sporty man (one of the least fittest man in the world!) so my childhood dream was always to be good at team sports and be admired by my teammates.
But we know how Demons like to play with their summoners, don't we? So even if I was expecting to be transformed into a manly Adonis with innate hability to be successful **in any team sport** my body was kept the same but I was granted with the ability to make **my team always win as long as I am playing along with them**.
### Rules.
After some trial and error I came up with the following rules about my unusual power:
* **I should be part of the playing team**: not Referee or this kind of Staff.
* **My sport performance hasn't been improved at all**, but it seems that my team performance improves a little.
* **The opponent team performance is affected**, they play as if they weren't having a good day: their mistakes are very common.
* **It should be a team sport**, I tried to play Tennis as singles and doubles and I only won when playing doubles.
* **It should be physical sport**, I tried e-sports and it didn't work at all.
* **All effects to my team or the opposing team aren't permanent**: as long as I'm not playing with them or against them, they act with the usual ability.
### Question.
I already gave up on becoming a successful sportsman, but I want to use this power to earn as much money as possible... but is not as easy as I was expecting: no one wants a fatty like me to be part of any team in any sport.
I've tried some sports betting and I got some money from that, but it wasn't a big deal because it was against some Basketball street players.
What should be my best choice in order to become rich? I want money! Lots! As soon as possible!
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Get some seed capital.
Find a league system where you can "rise up" through success---like football in some cases. Ensure that it is a game where injuries are rare.
(Less like football)
Buy yourself a team. It can start with just some friends. Play on it. You own it, so you can play on it. Ensure that the league rules (at every level) don't prevent owners from playing on the field.
Now. Win. Every. Game.
Especially because it doesn't matter who you have on your team, you should be able to rise up in leagues at a reasonably fast rate.
Play this up as you being amazing at picking talent, and you being on the teams is how you get a feel for it. Be quirky. "I can pick people who can win even down most of a man" basically.
The seed capitol can be gained through small team games like bowling, tennis, pool. Avoid gambling too much; you don't want to be offed by organized crime. Simply winning competitions should be enough; go for prize money competitions. Once you have a small amount of seed money, hire someone to find team games with short time frames from wanting to play with no history, to winning prize money, factoring in travel costs.
Start with some buddies who do it on a lark. As you can afford it, upgrade it to "general atheletes". To avoid accusations of cheating, have them do a bunch of strange mental and physical exercises which constantly vary. Ask them to humor you to start; sporters are highly superstitious. You'll get buy-in.
As part of the ruse, tell your team mates to play in completely unconventional ways. You know you'll win, so how they play tactically *doesn't matter*. People will attribute the team's success to that instead. The crazy tactics should again vary constantly without pattern (consider using dice) so others won't be able to suss out a pattern, duplicate it, and be justifiably surprised it won't work.
Examples:
* Bowling
+ Use only your thumb
+ Throw with two hands
+ On tippy-toes
+ Backwards
+ Always through a gutter ball on your first throw
+ Give it backspin
+ Lick the ball
* Tennis
+ Backhands only
+ Close your eyes on every swing
+ Always aim for the left side
+ Volley it up in the air
* Association Football
+ Only one offensive player
+ Only one defensive player
+ Everyone wears an eyepatch
+ Keep your hands behind your back
+ Stand on your head for 1 minute before the game
etc., etc.
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You are going to have to rise up in an amateur team sport, then make the jump to a pro level. Something where you can enlist your friends and ensure they realize WHY they are winning. So pool, billiards, etc. The prize money for these things is usually in the tens of thousands in major amateur competitions, but once your amateur team keeps winning you can jump to the pro leagues, get sponsorships, etc and get the big bucks. Sponsorships will undoubtedly be your major income stream.
You won't be able to crack pro sports teams because your poor physical condition won't let you make it through selection. Even joining a minor league team (of baseball, for example) won't help because while the TEAM wins, that will be attributed to players other than yourself (since you are not a great player). So even if the opposing teams play terribly, the other payers on your team are the ones scoring, blocking, getting yards run, etc, not you.
So you need to pick a sport where joe nobodies can pay to enter and climb the ladder, unless you can somehow convince a pro team manager to hire you, despite your poor performance, and keep you on when the team is winning and everyone is screaming to replace that slob in the outfield who always misses a ball in his area and is totally being carried by the rest of the team.
Pool or bowling prizes and sponsorships probably aren't much compared to basketball or football, but certainly enough to set you up well in life. Of course if you only win because the opposing team screws up ROYALLY EVERY TIME, you will eventually get blacklisted (and accused of cheating somehow), or become some sort of joke team, because otherwise a couple of average joes will never stand a chance at the pro level.
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Find a bad, amateur team. Teams must exist that have a really awful record.
Dress yourself up as a lucky mascot of some sort.
Blag joining in on a game - as the mascot - because it's 'lucky'. If necessary, ensure not enough players make it to a match one day. For amateur leagues, this is probably as easy as 'letting someone's tires down just before the match'. And then volunteer to 'make up numbers'.
Your power will kick in, and they will win, and attribute it to 'lucky mascot' syndrome.
Once it's happened once, you can probably swing 'joining in' again, because ... well, it didn't go *too* badly last time, did it guys?
But the important point would be - they need to go from mostly sucking, to mostly not sucking, quickly.
It might take a season - but after that season, people will realise that the 'lucky mascot' effect has worked, and is no more absurd than some sporting superstitions.
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How about Martial Arts? There is a [Team Fighting Championship](https://www.youtube.com/user/Teamsfight) in which you fight as a team. That means that your team should win. If your ability means that your opponents make mistakes you can easily show that you are capable of knocking out your opponents.
Like other people already mentioned you should start with amateurs and make your way to the top. But it will probably be easier. If your opponents make mistakes while fighting you one-vs-one you can show that you are a pro by knocking them out (sort of...). This will work, because it is still a teamfight, even when you are at a single moment fighting one-vs-one.
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Create your own team, on the sport that you like the most AND produces lot of money in your country. You probably would have to start it in an amateur league, and probably pay very young rookie players to join you. Say you will be the coach - player, and take the less demanding position that effectively plays.
Play your first season up to championship, take a few days off just not to have a perfect record (especially easy matches that your team may win without the spell), substitute yourself when you have a plentiful advantage, so people may notice the lucky spell but also you may be able to deflect it to your greatness as a coach and developing your players.
Once you win a league, join the above level; two or three years your team gets pro and good sponsors as a Cinderella story of success.
Ride it all the way to winning the top league, continental championship, and world championship on the sport. Then sell your successful team and retire!
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Put in the work.
After picking a sport, train. Try to get as good as possible. That way, it's not such a crazy stretch to field you.
Doesn't sound like there is any curse prohibiting self improvement.
If you can get a team together for some Pro-Am thing, you're good. Quick cash. Run through those getting as much training as you can, hopefully finding a pro who likes you.
Explain things over drinks, but try to sound "sports-superstitious" and not "diablerist". Probably skip the pact bit. Caught a leprechaun napping, maybe, or a djinn bound to a jockstrap.
This guy introduces you to your best niche role and the people who can use it. If nothing else, he knows the people you'd need to convince to let you play.
(Btw, depending how you worded the wish, sulpher boy is on the hook to help.)
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You've already been part of many teams, so you probably know some people. Find in a team an important guy that is your friend and you trust him and convince him of the truth. He will surely look for a way to put and keep you inside the team.
You won't be the star player, but after some victories, your friend may be ready to gather some other important guys from the team and give you a good wage in order to keep you in the team.
You could do this for more than one team (but not many), so they would "fight" for you ensuring you a lot of money.
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**This question already has answers here**:
[Robotic Replacement for Infantry [closed]](/questions/56767/robotic-replacement-for-infantry)
(5 answers)
Closed 7 years ago.
In science fiction and real life, robot designs vary quite extensively, and rightly so as each design is meant to tackle a different task. A more common design is based on the human form: four limbed, bipedal, head on top etc.
But what would be the best design for an all purpose robot designed to replace military infantry? Humans are able to accomplish a wide array of tasks and yet I feel a robot designed to look human is quite limited. Should it even have limbs? How many? Should it have legs? Wheels? Both? How big should it be? Is human size too big? Too small?
I would like it to be a single structure, so no nanobots that can form bigger bots. Consider the budget to be incredibly vast, so don't worry too much about what it costs.
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I think it would not be one frame. Just as you don't have only one model of tank, and one model of ships, you would have a array of different robots optimized for a specific role/terrain.
Exemples:
* Need to deal with civilians, and you don't want to make them afraid? You don't need a lot of firepower, but have something they can relate to, so a humanoid form.
* Need to rush buildings and just make them go boom? A cat like or toy car suicide bomber like [Goliath tracked mine](https://en.wikipedia.org/wiki/Goliath_tracked_mine).
* Secure a area already under control (road barrage)? Some sort of mini tanks with appropriate weaponry should be perfect.
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For a military combat robot, I'd prefer a dog or cat style design.
4 legs for speed and manoeuvrability and a low centre of mass. Main weapon on the side, left and right, to cover the complete 360° area around and above the robot.
Main sensors in the head, containing IR and optical sensors, ears are supersonic radar, similar to bats. A tail as an electronic whip for close combat and a smoke grenade launcher in the butt, to cover emergency evasive manoeuvers.
The military transport would be similar, just bigger, horse sized, and without weapons, but a big storage in the armoured belly, big enough to hold a grown human in embryo position.
I would not recommend bipeds, because the high up centre of mass and the unstable position when only one leg is on the ground.
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There is NOT an *optimal* shape, ESPECIALLY for military use.
That's not the way military things are designed: think about *general purpose* airplanes, boats and submarines. Those projects are often too full of compromises and they're sub-optimal in every scenario. For each intended use (or, at best, for a family of uses) you need a specific design.
Few things to consider (but there are many more):
* Bipeds and quadrupeds aren't the best for equilibrium (tripods are far better because for three points there is always one plane). *Best* is a vague concept, they may be *flexible* and provide a great maneuverability paying the cost of increased amount of energy (and complexity) used to keep balance. However quadrupeds may be better to carry heavier stuff. Consider that:
+ **Mass distribution** (just for example think about crossing an iced lake) is important; more *legs* and better you distribute weight.
+ Quadrupeds are more stable than bipeds and, distributing mass, you may need smaller, less expensive, infrastructure.
* Simpler design is **easier to produce** in case of war and it's cheaper (again it's very important for volume production in constrained resources scenarios).
* World is **designed for bipeds** (human beings) and if your *soldiers* need to interact with such environment then two *legs* are better (also with a comparable size).
* We already have a huge amount of **existing weapons**, to redesign them to fit those robots isn't viable (at least at very beginning). It's much better if they can *handle* what already exists.
* Sometimes wheels, skates, etc are better than *legs*. Again it's about intended use. Do you easily walk above snow? What's the maximum speed for a reliable device with high complex moving mechanical parts (like legs)? For military components **reliability** is the master.
* If your soldiers will need to **interact with human beings** (for example for pace keeping missions) then an humanoid shape (but not too much humanoid) is more appreciated, regardless their effectiveness in combat.
* According to **combat environment** you will need completely different shielding and it may then impose completely different choices.
* **Different missions** impose different *soldiers*. Infiltration? Smaller and fast (probably with less shielding). Frontal impact? High shielding and speed is less critical. Quick response? Faster and with huge impact, probably leaving thick shield out...
* **Technical limitations** will impose their own rules. Do you want a fast, highly armored tripod which can combat for one week inside enemies' country? You probably don't have the battery to power such soldiers...
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This may not be the answer you are looking for, but I'm convinced it will not look any like a human. An ideal military robot is bacteria-like. Very small, very deadly and present in very big numbers. It probably also should be able to propel itself, so it could move much faster than usual bacteria.
In practice it may be very hard to design something so small, that can move very fast. So in the end, it may be much bigger but still will remain similar. Imagine a small balls, almost not noticeable, but that can move very fast and kill in seconds. Maybe something like an AI-powered bullet or rocket?
If we assume we are not so much technically advanced, it will still be small, just bigger. The drones, that carry a firearm is a good example. Other option is something like a small spider that can jump very far and fast. I do not remember the movie name, but there was one (probably more than one) that showed one of such things.
All of this if we assume a real warfare - combat. If we are peacekeeping, surely something humanoid will work better, but I guess this is closer to police task, rather than military.
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# Humanoid
I'm anthropomorphising of course, but a humanoid shape is pretty optimal (since we evolved over millions of years into our currently optimal shape and size).
This becomes more efficient when robots collaborate on tasks as well.
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While @Pete is right, he failed to provide a reason, which i would like to provide.
There are many good generalist shapes. To be precise, every living thing on our planet (and elsewhere, should there be any) has a really good generlalist shape.
But there is only one shape that can benefit fully from the environment shaped by humans, and that is the humanoid form, precisely for that reason:
Everything around us is optimized for our form. Shelves and cupboards are where a humanoid can reach them easily. Any machinery you find is built for humans to operate.
And this is especially though in warfare: Every weapon is designed so a human can easily distinguish the right end from the wrong end, and use the trigger, reloading mechanisms and whatnot.
So, if you want a generalist combat robot, give it a humanoid form, so he can ride in tanks and aircraft, use weapons that the opposing side spontaneously decided they won't need any more, and reach any places that humans can.
Feel free to add fancy extras, but make sure that the general features are kept humanoid.
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In order for our bots to be as efficient as possible and be usable in as many different environments as possible, we're probably not going to see any humanoid bots. The sole exception to that would be if we needed some sort of psychological edge, in which case, mounting our bots in child-mannequin bodies would be ideal.
Nightmare fuel not withstanding, first of all we need to look at mobility. The ideal combatant is one who can be deployed in a short time, in any terrain and through a wide variety of means. So we'll want them to be reasonably small and light. This helps both with transport and because they're small, they'll be harder to hit. In terms of surface area versus volume, we're going to want them to be as close to a sphere as possible, giving us a maximal volume to hide important components while providing a minimal surface that we need to slap armor on. Unfortunately, spheres are annoying to deal with and tend to roll around a lot so we'll probably see something closer to a dodecagon (which co-incidentally, also looks an awful lot like the angular shapes we see on radar-confusing vehicles)
Allright, so we're looking at bots that are probably somewhere between a football and a beachball in size. I think that in terms of weaponry and mobility, we should be following the example of the A-10 Warthog. That is: half of our bot is firepower, the other half is dedicated to getting it someplace where it can deploy said firepower. I'm thinking a number of small ion thrusters, set in different locations in the chassis.
As for weaponry, since we're dealing with warbots in the future, we're probably building them either with high-end coil or rail rifles, with the whole of the bot built off a miniature reactor or big-ass battery.
Speaking of weaponry, some of our bots are probably going to be intended for short-term engagements and should be equipped with a battery of dumb-fire rockets for harder targets.
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Here at Real Soldier Corporation we've designed the optimal hybrid robo-warrior.
As Real People™, we are [pretty efficient](https://physics.stackexchange.com/q/46788/7456) at converting fuel to energy, and able to harvest energy from a wide source of foodstuffs. But most importantly, we're really efficient at moving through a variety of terrain. We can climb over, under, and through things. Our infrastructure is also fairly well designed around something us-sized.
We've designed the fighting force of the future. Our newest product, Meat Soldier™ overcomes many of the design problems that Real People™ soldiers have faced over the years.
* **Frailty**. The most tragic design flaw in Real People™ is that a small projectile through the heart or head stop operation. We have engineered Meat Soldier™ with redundant fluid pumps in various locations throughout its body, with smaller emergency pumps in each of the limbs. Meat Soldier™ is capable of continued, though limited, operation even in the unlikely event that every Meat Heart™ is compromised. We have also [carefully designed the circulatory system](http://askanaturalist.com/why-don%E2%80%99t-ducks%E2%80%99-feet-freeze/) to increase the range of temperatures our Meat Soldier™ can operate without tissue damage
* **Sensory input**. While Real People™ are limited touch, taste, sight, smell, and sound, Meat Soldier™ can be equipped with a wide range of Sense-Stations™. They can view wavelengths in the entire spectrum, including infra-red and ultra-violet. Their auditory frequency response can be expanded to 0-10,000GHz, well outside the range of human hearing, but allows Meat Soldier™ to communicate at higher frequencies, as well as identify other signatures made by certain electronics. Sense-Stations™ are not just limited to their point of attachment. Using proprietary technology, most Sense-Stations™ can be re-attached at different points, allowing for maximum flexibility in where and how your Meat Soldier™ can see, taste, hear, and touch.
* **Speed of Communication**. About the fastest you're going to get using Real People™ communicating via English is 200-300WPM. [583-630, if you're really good](https://www.youtube.com/watch?v=qv4nimqsajA) (but good luck trying to process that). Our Meat Soldiers are able to broadcast information [much quicker](https://android.stackexchange.com/a/28749/8854). Typical communication is digitally over WiFi or Bluetooth®, but Meat Soldiers can also fall back to auditory communication. Communication is encrypted using AES-256 bit by default, and if you have the need to communicate with your Meat Soldier™ through the auditory channel we have an implantable cochlear implant that can perform real-time decryption. If necessary or desired you can also instruct your Meat Soldier™ to communicate using decrypted audio in the language of your choice, making them ideal for situations where you may require an interpreter. Other scenarios that the Meat Soldier excels - imagine that your Meat Soldier™ has found Bad Guy™'s Bad Guy Hideout™. Using the full-spectrum Sense-Station™ package, including optional Hand Eye Coordination™ Sense-Station™ package Meat Soldier™ only needs to expose its fingertips to gather the most intelligence with the least amount of exposure, confirming that Bad Guy™ is on the premises. In a Real Person™ situation, coordinates and confirmation will have to be communicated via at least a whisper, but upon confirmation, Meat Soldier™ can silently radio back its exact route and entire Meat Soldier™ Intelligence Package™. Its fellow Meat Soldiers™ will now know the *exact* route to the destination, along with all intelligence gathered along the way, such as potential ambush points, dangerous terrain, weak spots in defense, sensors, booby traps, etc. Of course, if the situation changes, Meat Soldier™ is capable of making real-time adjustments to the battle plan, but in the typical case the entire Meat Soldier™ unit can walk in the exact footsteps of those before it, so any track will look like it was only one individual.
* **Hesitation**. In battle hesitation will kill a Real Person™. Meat Soldiers™ have no hesitation. When a threat is identified, it's eliminated. Because Meat Soldier™ units can act in nearly immediate communication, if necessary, one Meat Soldier™ can identify the target while another one eliminates it. Best of all Meat Soldier™ has no regrets, no remorse, and no PTSD!
* **Infection/disease/loss of limbs**. For Real People™, disease and infection can cause pretty serious problems. But our new Meat Soldier™ Grow and Go™ accessories allow you to plug and play new limbs. Our carefully engineered process produces limbs to such a high specification that a damaged foot, arm, or leg can be replaced simply by detaching the old one and plugging in the new ones. And if a Meat Soldier™ is rendered inoperative, any viable limbs can be harvested by its compatriots.
* **Rest/Fatigue**. Granted, more stress will wear out Meat Soldier™ quicker and may void your warranty, but in an emergency situation, Meat Soldier™ has override commands that can disable self-protection routines, allowing them to push themselves far past that of Real People™, completely ignoring injury. And of course the Intelligence Package™ will be recorded and transmitted to other Meat Soldier™ units so your only loss is that of the actual parts. Meat Soldier™ has no need to sleep, so they also get 8-10 more hours of productive time per 24 hour cycle, and one Meat Soldier™ can operate heavy machinery indefinitely.
* **Variance**. With your typical Real People™ they can be tall, short, fat, skinny. Some have more endurance, others have less. Each Meat Soldier™ model is engineered with such high quality and attention to detail that they are almost impossible to tell apart by default. Of course we offer patented SkinTint™ technology and MeatToo™ tattooing to meet your branding needs. We offer three primary Meat Soldier models. Meat Soldier™ Classic has an average build, at 6'0" and weighing in at 180lbs unloaded, and capable of carrying 90lbs fully loaded. Tunnel Rat Meat Soldier™ has a slim build, coming in at 4' and weighing 65lbs, capable of 25lbs fully loaded. The Tank Meat Soldier™ model comes in at 6'5" and 325lbs, capable of carrying a 200lb load. Typically you'll want to match parts with the same model, but in an emergency situation you can interchange limbs between any line of Meat Soldier™ as they have been designed to work with every permutation of limb attachments. Having such consistency in our models allows you to tightly optimize your base layout and armor configurations for your Meat Soldier™.
* **Learning**. While Real People™ take quite a while to master a new skill, Meat Soldier™ sKill Transfer™ is almost immediate. And unit-to-unit transfers require no training time, so if one unit is lost or damaged, its experiences remain. If a skill is unnecessary, or the experience is atypical, it is also possible to remove sets of training data from your Meat Soldier™.
These are some of the many benefits to having your very own force of Meat Soldiers™. As the Real People™ behind Real Soldier Corporation, we look forward to your business.
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# It's simple:
[](https://i.stack.imgur.com/9yy5D.jpg)
The best soldier is that which you can't fight. Soldier of the future would either use the best camo available(which, in some distant future, might mean high % of invisibility), or simply won't be a single soldier(swarm of nanobots, some disease, or any other modern invention).
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In the animated movie **Monsters Inc.** the monsters which populate the universe all look very different despite the fact that they are presented as being the same species (since they can interbreed).
This begs the question, how can a species exist that has thousands of different forms?
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Well, through controlled breeding people have managed to isolate certain characteristics in dogs to the point that even though they are the same species they look significantly different.
However they all still have the same basic biology: four legs, same general shape, a single head with two eyes, a nose, a snout, etc. In Monsters Inc the situation differs significantly.
Some monsters are based on lizards, others on insects, or mammals. Not only do they come in various shapes and sizes, they also vary in the number of limbs they have, the powers they demonstrate (invisibility, flight, etc.), and other critical characteristics which typically define a "species".
So I suggest we take a step back and allow all these different creatures to actually be separate species. However, let them **be** actual animals. ***Monsters***.
And let the intelligent species be parasitic in nature, inhabiting the body of these monsters and forming a society in which each individual wears the body of a monster the same way that we might wear a suit.
>
> Basically, think along the lines of what the alien invaders in "The Host" are.
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examples from earth include dogs, which can nearly all interbreed despite radically different shapes sizes and colors (although, this is arguably not "natural" given the human selection pressure). also, snow goose blue and white morphs. you might also consider the radical sexual dimorphism in various species (e.g. birds of paridise). or even radically different stages of some animals (larva, nymph, catarpillar, butterfly)
more generally, appearance is a function of genetics and selection pressure. typically, a species seeks uniformity in appearance since visible deformity is correlated with genetic damage and defects. there are however some parts of the genome where diversity is highly valued. there has been some research to suggest that human females are more attracted to males when their immune system genes do not line up.
perhaps you could invent a world where some sort of predator or pest would attack animals that look similar. then there would be genetic selection pressure to ensure you children did not look like any other animal of your species. this selection pressure would eventually be reflected in mating preferences and accelerate the diversity.
example selection pressures:
1. once "the swarm" consumed a large red 3-armed smelly hairy thing, it would proceed to consume all large red 3-armed smelly hairy things before going dormant again.
2. to take dogs as a model, perhaps "the overlords" like variety in their pets, and occasionally cull out any sub-species that becomes too common.
3. looking specifically at "monsters inc", perhaps human children would eventually become accustomed to the appearance of a given monster and stop screaming. if your spawn required human child screams to survive, then being a novel (and therefore scary) shape would give them a competitive advantage.
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You could achieve a reasonable amount of variation by granting your species a high level of phenotypic plasticity. This is where the morphology, behavior, physiology, etc are changed as an individual grows.
These differences are decided by environmental pressures, such as tadpoles gaining more rotund bodies in order to make it more difficult for salamanders to swallow them, or bichirs gaining more robust shoulders, and walking more efficiently, when growing up on most land, as opposed to in water.
If you choose to take this a bit further, you could have a plausible, and in my opinion interesting, result.
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It is possible if your species is artificially created. This species would be assembled from the DNA of multiple other species. Each creature has a different combination of DNA donors, but all have the same base line donor.
For an example if your using humans as your base line, then you could breed a human-bear-bird chimera with a human-whale-starfish chimera, to produce a hybrid.
however ever it possible that whatever children the chimera had would not be able to reproduce. (think of mule)
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I'm using [this question about likely forms of government for a space colony.](http://worldbuilding.stackexchange.com/questions/28642/what-would-be-the-most-viable-form-of-government-for-the-first-space-colonies)
What sort of legal and penal system might develop on such a colony?
This is a pretty broad question, so assume the following constraints and requirements:
* The colony has a hybrid democratic/republic & military government structure
* The colony has a hybrid capitalistic & socialistic economic system
* The colony establishes laws regarding minimum colonist contribution to society
* The colony permits exceptions to the minimum required contribution for certain socially desired/encouraged activities (raising children, security services, defense forces, etc.)
* The colony permits colonists to "bank" their excess contributions as a reserve against unemployment and disability.
Essentially, I'm looking for how likely the colony will actually mete out a death penalty to colonists who consistently fail to meet their minimum required contribution. You can consider this minimum as "earning your air" type of problem. It really equals the minimum tax regardless of occupation.
OTOH, the colony guarantees certain positions will always earn the minimum and the people in those positions will always get the minimum necessary to survive. As long as there is enough work to do, there's no problems.
The problems will occur when either someone in one of these minimum pay positions fails to meet employment standards, someone has long-term disabilities, someone refusing to do even the minimum pay positions, or other issue like that.
On one hand it seems extremely cold hearted to execute a person for this failure to perform. However, on the other hand the survival of the colony is at stake. If too many people flout this law, then the entire colony could fail.
**How likely is a space colony going to stick with capital punishment to rid itself of colonists unwilling or unable to "earn their air?"**
***Edit 4/11/2016:***
I envision the colony as being a Lunar or Martian colony early in its establishment. They're doing just well enough to not need a military governing structure but they're still living on the razors edge of having enough resources for everyone to survive.
It may be possible for one to a small number of "lazy" people to not pull their weight, but they really can't afford a welfare state. There's not enough excess production of the essentials (air, water, food, power, etc.) for them support even a small but substantial percent of the population who can't or won't work.
I really intend for this to be a social experiment. I'm looking for reasons in favor of supporting them - with justification or killing them - with justification.
I think the level of commitment by the officials to executing those who won't or can't pull their weight to be on a graded scale. Clearly someone who is sick or hurt and has a high likelihood of recovery is worth keeping. So are children.
* What about someone with high prospect of surviving but a low prospect
of ever contributing to the colony again?
* What about people perfectly capable of pulling their weight but
refuse to do so?
* What about people who are destructive of property (especially life
support equipment) and or violent?
But they have to draw the line somewhere. Where is that line?
I am also viewing this question as a societal one - not necessarily as a dictatorial ruling form on high. The punishment for the crime of not working was set by the citizens of this society. I suppose I could see it working like this:
1. If you don't "earn your air", then you're assigned to a work detail.
The assigned work detail does the scut work that has to be done but
no one wants to do.
2. If you fail to appear for your assignment or don't get enough done, then
you're demoted to a work detail that does dangerous work that has to be
done.
3. If the detail to which you belong doesn't meet its quota then they entire
detail must continue doing these jobs until it does meet its quote.
I suspect then it is in everyone's advantage in the dangerous work detail to get the job done. And people who don't adequately contribute suffer "unfortunate accidents" at the hands of the others in the detail.
Such a system is obviously going to suffer from abuse and morph into something it was never intended to. But it may be quite an interesting transition.
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Based on the idea that your colony is labour limited, then most of the legal punishment would be built around the idea of indentured servitude. A non violent criminal or debtor would most likely be sentenced to work for a set period of time in order to fulfil the requirements for restitution and retribution (and possibly rehabilitation).
Violent criminals will have to be dealt with differently, either locked up in a secure facility (possibly separate from the colony itself) or dumped out the airlock, because the environment is too close and insecure to risk having them around.
The longer term effect of this sort of environment might be to create a social class of "Helots" who are legally enslaved by the state in order to work off their debt to society. Since the colony requires a lot of labour, there will be incentives to make laws stricter and enforce Helotage in order to have a captive work force that is fully employed at whatever is considered high priority in the colony. This also implies that there will eventually be a class of citizens who have avoided being indentured and are receiving the fruits of the Helots labour.
In the short run, this might even gain short term efficiencies, but in the longer run, a free market capitalist system will allocate labour much more efficiently through the wage and price mechanism.
And of course Helotage isn't the sort of social system which encourages cooperation and social harmony, the real Helots on ancient Lacedaemon were said to wish to "eat the Spartans raw", and the fearsome warrior culture of Sparta was developed to have a standing army capable of dealing with slave revolts. A colony which evokes along these lines may eventually have a series of concentric or separate compartments, with the Agoge housing the upper class "Similars", while the lower class perioikoi and enslaved helots are contained in separate compartments, with their labour allocated in accord with their levels of indebtedness or legal standing compared to the "Similars".
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Legal systems do not exist for their own sake. We do not punish people "just because" or "we have always done so". Legal systems have one or several **purposes**.
You need to take a step back here and start thinking about **why** you have a legal and judicial system to begin with. What are you trying to achieve with it and what are the pros and cons of what you are doing in relation to your goals?
Law Enforcement is — generally speaking — fulfilling the following needs:
* **Protection**. Hindering people from acting unlawfully.
* **Prevention**. Making people not want to or need to act unlawfully. Deterrence, i.e. scaring people into not acting unlawfully, is a part of this.
* **Retribution**. Exacting revenge on people that have acted unlawfully.
* **Rehabilitation**. Giving treatment to people so that they will not act
unlawfully again.
* **Reparation**. Making sure that people that have been
acted unlawfully upon are compensated for their pain and/or loss.
Dive into the [science and philosophy of justice and law](https://en.wikipedia.org/wiki/Jurisprudence), and these are the founding principles you will find.
On Earth, sparse manpower is not really a very great issue. For the most part it is the other way around: we have too much of it, or of the wrong kind, and we cannot keep everyone occupied. Here it does not matter so much if we take people out of the work-force. We can afford that.
Your space colony is a very different place. There you cannot just put out a "Position available" ad and have someone fill the slot. This means that the priorities get shuffled around. You need to think about which of these principles are the important ones, and then weigh the outcome for applying these different principles against what your goals for the space colony is, or if they even matter. Is for instance **retribution** an important goal? Is the thirst for revenge something that needs to be considered here?
So to go into specifics: is it likely that capital punishment is a viable and good tool for achieving the space colony's goal? Eeeeh... probably not such a smashing idea because even if it is an excellent way of making sure that the cuprit never does it again, and while it does act as somewhat of a deterrent, it will be hurting the work-force. Also the rest of it will most likely **not** be all that keen on living under the Damokles sword. Tyranny is seldom a good way to keep people content and productive.
Into this then also comes other social contracts. What are the obligations of the space colony towards its denizens? Under what conditions can you enter the space colony? Under what conditions may you leave? What are your rights and what are your obligations? Add some further complications: how will the people react to the laws, their rights and their obligations? If people are born into this and they are for instance physically unable to leave, will they really be content with knowing that if they do not work they will be put down?
There is a great deal to take into account here and you have your work cut out for you. I hope that as far as law and justice goes, you have a little bit clearer picture of **why** we have those things to begin with.
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It may help to look at alternatives and consequences in your world. What are the alternatives to execution? Can people be deported easily? Can they be forced to work? If so, are there menial jobs to occupy them?
You say that raising children is a socially desired and encouraged thing to do. This leads me to guess that your colony is labor-restricted rather than resource restricted. If this is the case, the general trend ought to be more toward accommodating/rehabilitating under-producing individuals.
But let's also look at consequences. When you say "earning their air" and talk about the colony failing if too many people don't contribute, that leads me to think that the colony is living fairly "close to the bone". How close is your decision. The greater the consequences of one person not contributing, the harsher punishments will tend to be. If fresh water is rationed and people are suffering hardship, they will tend to deal harshly with those who consume and do not produce. Particularly if there is a perception that the non-producers do so from selfish motives. What form this harshness takes will tend vary with the amount of deprivation that the average citizen is experiencing. People will take desperate measures when their well being and that of their loved ones is at stake. Imagine if your child had to go to bed hungry and would continue to go to bed hungry because the lazy (fill in the blank) people won't get off their fat behinds and do the minimum day's work. It would not be hard to imagine things getting ugly.
I believe that people are decent on the whole and that mankind as a whole continues to get more and more decent as time goes on. But we must remember that in historically recent times public executions were considered a form of entertainment. Given certain social pressures, it is not inconceivable that we could regress to that stage.
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Your setting seems completely unrealistic.
You cannot have a space colony under normal circunstances governed like that. No one (at least, no one who you want in your space station) is going to sign in if they know that, if they suffer a crippling accident, they will be in the short list to being slaughtered. And, without reason, nobody that signed for a more reasonable environment will accept such a change. Even if the situation requires certains sacrifices (v.g. not having kids, or that medical care will not have the same level that in Earth), those would have been explained and accepted **before** anyone leaves Earth (both in the interest of your colonizers and your own interest).
Additionally your recipe of "if people does not appear to work send them to a more dangerous work" is a call for your population putting you in a space suit and ditching you outside the colony.
And, last but not least, if you are paying the considerable expense of putting someone off-world (both as their salary -think of off-shore oil drillers- and the cost of putting them in space), you most likely will have conducted an in-depth analysis of your candidates. You won't fill these positions as if you were hiring fast food workers. There are always surprises and individuals who end not fitting as well as expected, but those should be a very limited minority.
And, with the level of automation to be expected in such a station, you do not expect it to be much work to keep the life support systems... if you have a hydroponics stations, you need someone to get sure that water and light are available and within parameters, as long as there is water and light the plants will grow and adding more workforce to it will not help them growing faster. In such a colony, you expect that a lot of the workforce will not be used for survival but for building expansions of the colony, doing research, mapping resources for following colonization waves. To send a lot of people into space just to barely survive is a gigantic waste of resources. So, either you can keep your life support working without too much work, or you cannot keep it working (if it needs industrial supplies provided from Earth).
The only possibility to achieve a situation similar to the one you describe would be an unexpected emergency (note that the station should have been designed to deal with "reasonable" emergencies). V.g. due to war or other issue no supply ships are expected for a long, long time. The expectatives of each specific situation will weight a lot in the evolution:
* if there is hope for relief it is easier to keep the community working together;
* if people thinks the colony is doomed people will begin demoralizing, trying to hoard resources, fighting against each other; no laws that you can think of will stop that (but some laws may speed the process)
* if the colony has lost life support capacity (so it may be viable, but not without reducing population), possible outcomes are execution by lots (if people trust each other enough to trust the fairness of the selection criteria) or civil war.
In relation to enforcement, though, the colony provides way more refinements than you imagine; in fact, due to the fact that nobody can reliably leave it, control is far easier than in Earth:
* Someone breaks in a fight? Two weeks in detention, being allowed to leave his appartment only for work.
* Burglary/assault? One week without food.
* Rape/murder? Banished for life to an isolated wing with other criminals.
* You need to make an example of someone? Put him in a space suit and drop him far away from the colony, tune the colony PA system to that suit radio.
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Laws develop over time based on major events. Where I would start is piecing together a timeline of rough events. The large events are ultimately what will create and shape public opinion regarding the laws.
At some point, humanity is going to go to space on a much larger scale than present. Those individuals will feel loyal to their Earth nations and to their local communities and ideas they left behind on Earth. As more and more nations come to space, of course there will be a lot of different cultures and ideas brought to space. However, space travel is and always will be incredible expensive. So therefore, it's a safe assumption that the people who start out going to space come from wealthy nations or nations with sufficient wealth that make space travel a strong priority. Examples likely include America, Russia, China, Canada, Japan. Basically, look at what nations are already in space or planning space programs and imagine them all in a room together. Those are the interactions of early space exploration.
For the early time, any space conflicts will base around these Earth nations. This is very similar to conflicts in the new world as it was being settled - all based around European nations. It will take a few, maybe even several, generations before people start to develop separate identities from Earth. This will happen as individuals are born in space. However, their parents will have an influence in shaping their lives, so they will retain many ideas of right and wrong from them.
At some point there will be a separation event where those space civilizations decide to part ways with their Earth nation identities. Typically, this would be something morally opposed by those individuals, or something that creates excessive economic hardship. Some ideas may be an additional tax that is unpopular, a declaration of war which the space individuals don't see as agreeable, or the defunding of space programs, leaving the space civilizations to fend for themselves. You want to create this event as an emotionally significant event. People are driven by emotion.
So the laws are going to be based on Earth-nation laws, with tweaking as that independent nation sees fit.
Regarding your death penalty law, something of that nature is likely to have very strong opposition. Humans generally regard killing someone as wrong. In order to accepted, it would need to have:
* A very powerful, militaristic government. Essentially, a dictator in power who rules by fear. You would have to determine how someone is able to obtain this level of power, and how they would evade the many hundreds of people both in space and on Earth who would want to remove them from power by any means necessary. For that reason, I don't think a government like this would last long, but it's certainly one option you could use.
* An economic crisis in which many people are in a desperate situation. Bonus points if people die as a result or there is extreme scarcity. Think of Germany prior to the second world war. These individuals would be labelled, something like vagrants, and socially shunned. They would be isolated and blamed for the economic crisis. Again, I see a lot of societal pressure to take out a government like this and to prevent from killing these people. But it is entirely probably that this temporary situation could exist for some time out of a strong fear environment.
* A sufficient moral basis. The law is imposed on some basis which is easier to swallow. It could be considered eviction. The captain of each space ship or space colony house owns it and can decide who lives there. Those who could not afford the higher-price living accommodations would be forced into overcrowded facilities for the poor. If the mortality rate in these facilities was sufficiently high, then that could be a moral equivalent, because you are effectively condemning someone to a reasonably certain death through that eviction.
All in all, though, I think most likely that those who could not contribute would be sent to Earth or confined to less suitable living areas, rather than killed. And it's most likely that effort would be made, for the most part, to keep those facilities at a level of operation where the people inside don't die. I don't think anyone would be deliberately killed for non-violent crimes except perhaps for very brief periods of the space exploration timeline. And I think that anytime you have people dying, there are always going to be others trying to stop that from happening, especially when you consider that each and every one of those people is likely to have family and friends who care about them. So I do think you have a challenge to create a compelling and realistic narrative in this regard.
Good luck!
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I have pondered the same ideas extensively myself. I wrote a medium article about [the political system of space colonies](https://medium.com/@Jernfrost/a-non-american-perspective-on-a-mars-society-833f7ff76ece).
What spurred me to write it was in fact the frequent assumptions, in particular in American discussions about a space colony resembling some sort of libertarian utopia or being a sort of harsh dictatorship.
I simply don't think that would be the case based on what we know from history and different forms of societies. What I explore my article is the experiences of historical societies living under extreme circumstances, as would be the case of a space colony.
One example I look at are dutch people during the golden age (1600-1700s) living in polders. A polder is an area surrounded by dikes. Much of the Netherlands is under water and under threat of disastrous flooding. In some way you can compare this to a pressure hull on a Martian base cracking. It would doom everybody living inside it.
An interesting observation here, is that it did NOT lead to a harsh dictatorship. Quite the contrary. It led to the development of some of the earliest democratic institutions in the Netherlands existing all the way up to modern times, which are the waterboards. The waterboards existed long before the country got united politically. One polder may have several independent cities but one shared waterboard. Waterboards were elected and authority over the maintenance of dikes. Waterboards operated even when cities inside the polder where at war with each other.
Other examples are Viking times Scandinavia and Iceland. Iceland was settled without any king or overall power structure. So it was quite chaotic and violent. However it led to the formation of a sort of parliament, where everybody could vote. It was also the legal assembly. The relevance to a space colony, here is that early Viking age Scandinavia did not have police forces or standing armies. Basically there was no law enforcement. A small population could not afford that. Native Americans, Inuits etc do not have police force either. Legal proceedings at the parliament (Thing) was thus more like negotiations. There was an interest in getting the law breaker to accept his/her punishment to avoid having to enforce it, as that was difficult and costly. Thus punishments tended to be quite mild, mainly fines. Even for murder.
Other relevant examples may be Israeli Kibbutz. These were socialist groups running farms and small factories. They could be 20-600 people or so. So possible similar to a space colony. They operated on communist principles, that people contributed according to ability and received according to need.
These did not operate on the assumption that harsh punishments were needed to get people to work. Getting people to work was not based on threats but on social pressure. People growing up in small societies living under harsh conditions are usually socialized to deal with that. E.g. for the Inuit, when people got too old, they would go and commit suicide. They were not outright killed. They would feel a social pressure to do so, knowing they were endangering their tribe. Remember a small knit society is profoundly different from a big nation state. The commitment people feel to their local society is very different from what people feel towards a state of millions of people.
Viking society could be quite brutal towards heavily disabled children. They would simply kill their own offspring if they were too disabled. I think this is important to understand with smaller societies. A lot more is based on custom and discussion in the society, rather than merely quoting some legal paragraphs.
As for welfare states. I think it depends on how you define it. IMHO a welfare state is not primarily about having lots of people sit around doing nothing. Rather it is just an evolution of what primitive tribes already do. Human hunters and gatherers typically share extensively. They help the sick and hurt. A group operating on purely selfish principles would not survive long.
Remember unemployment is to a large degree a product of capitalist society. Most unemployed people are unemployed because nobody will give them work, not because they refuse to work. A small space colony however I think would find it very wasteful to keep people unemployed. A company in a capitalist economy OTOH has no such concerns. It does not consider the needs of society at large only its own bottom line.
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I'm writing a story about an alien race that is blind and deaf: They communicate based on touch and scent, and have a tech level generally similar to us.
I'm assuming that they can measure frequency and amplitude of sound and light, even if they can't sense them directly.
Let's say they get access to our broadcasts of TV and radio into space, and they interpret the sound data into essentially a line graph of frequency and amplitude.
How much sophistication would be needed to separate speech from a dog barking, a door closing, or a laugh track, for instance?
I'm not asking if they could figure out what the language says, I'm asking if they could realize sound waves are providing meaningful communication.
This is related to my question [here](https://worldbuilding.stackexchange.com/questions/30471/how-could-a-blind-alien-race-interpret-video-broadcast-into-space).
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## They could absolutely tell that the received data contains information.
**However, they will not necessarily decode that information as sound**. There is nothing in a radio or TV broadcast that would tell them what medium the data should be converted to after it is demodulated and decoded.
Let's stick with basic analog radio transmissions to keep this simple. There are two fundamental types of modulation that you're probably familiar with: AM and FM. Which mean Amplitude Modulation and Frequency Modulation, respectively. Both use the concept of a carrier wave and then modulate that wave to send out a signal over radio frequency.
[](https://i.stack.imgur.com/BQXJE.gif)
The above plots are the signal amplitude with respect to time. The "modulating wave" in this case might be that sound wave plot you're hoping the aliens are going to discover. The carrier wave is modified by the modulating wave in two ways shown, by changing its frequency or changing its amplitude. The frequency of carrier wave, by the way, is what you are tuning your car radio to when you want to listen to the radio. If you tune to 91.5 FM (my local NPR), the carrier wave frequency is 91.5 megahertz, or going up and down 91.5 million times a second.
Amplitude modulation simply changes how strongly that carrier comes in to your radio while frequency modulation changes the frequency up and down (usually by a maximum of 25 kHz in either direction).
Your radio demodulates the received signal by removing the carrier wave, which leaves the original modulating wave for you to listen to. The electronics for these simple modulation techniques are not all that complex. We won't get into digital radio or television, but they're rather different.
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**Now, your aliens have received this signal**. They will likely be able to determine that it's being modulated, because it won't be like any radio signals that come from natural objects. Amplitude modulation is probably easier to figure out, but plotting the change in frequency with respect to time is also a simple thing to do.
But where do they go from there? They're left with a plot of a waveform that changes with respect to time, but no information as to how that signal should be used. For all they know it could be a control signal for a device that spins back and forth or it could be a touch signal sped up 20,000 times to compress the information. The might interpret it as the combination of sine waves at different frequencies that relay information based on the frequencies and their respective amplitudes (via an alien version of a Fourier transform).
They might make the logical leap that it's a signal meant to vibrate a diaphragm in an atmosphere, but as they have no concept of sound, that's unlikely. In either case they will may eventually be able to decipher that it is language and would be able to respond in kind. But if we ever met them in person, they would not be able to understand our speech unless we transmitted it to them via radio.
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What you describe is a typical way to process sound waves. We usually use a fourier transform (or sometimes a wavelet transform) to get it into that space. However, it's usually not a line graph, because there are many frequencies going at any point in time.
Why do we do it in frequency space? Consider this amplitude vs. time graph:
[](https://i.stack.imgur.com/88vs5.png)
Its not easy to distinguish the content. You'll have to take my word that that's Churchill speaking, followed by laughter, then a dog barking, and finally a door being slammed. However, if we put it in a frequency space (using a fourier transform, which is very easy as far as signal processing algoritms go):
[](https://i.stack.imgur.com/v7fJF.png)
As you can see, laughter is a bit harder to distinguish from speech , but you can see a lot more "content" in the speech pattern. The laughter is more repetitive with the same content at each explosion of laughter. Likewise, a dog barking shows a set of tones in the 0-2kHz region, while a door slamming is pretty broad spectrum. (The different clipped off regions at the tops arise because I got the sounds from different sources, and each one was compressed to a different level)
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They might develop similar systems for sensory substitution like we've done. Let me toss out a couple of links on the concept:
[Wired article](http://www.wired.com/2007/04/esp/)
[Wikipedia](https://en.wikipedia.org/wiki/Sensory_substitution)
The general gist of these is based around a concept called neuroplasticity; the idea that the mind can adapt to various input. Some of the more simple experiments deal with people wearing goggles that invert their vision (everything is upside down) but after a few days the brain adapts and the person carries on like nothing changed.
Another experiment from the Wired article involved a belt with several vibrating nodes (like in your cellphone) ringed all along its length. The only node that vibrated though was the one facing north. This gave a perception of magnetic alignment to earth's magnetic field (kind of like what we assume a migratory bird might have). The user said he had in innate perception of location and direction after his mind adjusted to the touch->direction sensory input.
Another use involved using touch to help the blind "see" again by way of electrical impulses on the tongue, providing a sort of three dimensional touch map of a room.
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While not being able to recognize light waves might work for the vision, even the deaf can 'hear'. Sounds is a form of energy that travels through matter. The engines of the ship will rumble, the thunder storms of their home planet will shake the ground. So while they might not have ears and specialized organs to 'hear' sound, they will still definitely have some understanding what it is and some way to interpret it, since it will impart energy to the being that can be 'felt'.
Now if they have enough of a sample that is recognized as alien generated in origin, they would likely eventually come to the conclusion that it is a form of communication.
Edt: BTW for this alien species to even make it to the stars, they need to already have an understanding through some sense of space and distances with the celestial bodies. Or what will stop them from running into anything? The easiest way is electromagnetic sensors of some kind. Some kind of gravity detection might be possible as well, though that is a much more subtle thing to detect and it is highly unlikely that an organism that evolved on a single planet would have any need to detect gravity naturally since it is generally the 'same' everywhere. So it would have to be some kind of tech, which came much later.
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The level of sophistication required, is to be able to **build a machine that converts audio signals into a tactile interface.**
E.g., blind people can read because a tactile from of the written word was created for this purpose. And also, the deaf can 'hear' what people are saying on TV via subtitles.
Note: To evolve tactile sensory, without ever gaining 'hearing', is strange indeed. Even the deaf can *feel* music.
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There's a society similar to ancient Egypt. Most soldiers are either skirmishers with slings or shortbows, or "heavy infantry" with spears and big shields, but wearing the same loincloths as the skirmishers. War chariots and big beasts like elephants exist, but they are rare and they don't get involved in most battles, at least in significant numbers.
Barbarians living on the periphery of this civilisation fight as skirmishers (valued as mercenaries for that!) and use a scorpion poison for their arrows. The poison doesn't stay active long enough after leaving the scorpion's body, so they partially domesticated scorpions. Trained scorpion-tamers hunt scorpions, place them in a scorpion farm and gather poison just before the battle. But this indirect use of scorpions is not what I'm asking about.
Perhaps this tactics was invented when some enemies attacked a scorpion farm: the scorpion tamers learnt to throw the scorpions. This is not very handy against skirmishers, but throwing few scorpions has a devastating effect on morale of a unit of "heavy infantry". Usually done just before allied heavy unit attacks the group running from scorpions or trying to kill them. Also, thrown scorpions can spook a war elephant, making it a neutral force attacking everyone, not just us.
After scorpion-throwers became relatively common, an invasion occured. The invaders wear chainmails, their heavy infantry is trained to cut through our spears and shields with their steel swords, their archers wield longbows or crossbows and their cavalry is clearly superior to our chariotry. Elephants are quite efficient, but after few battles they learnt the "road" tactics, so the elephant runs through empty space and leaves battlefield while the mahout catches a bolt or two. Guerilla tactics is better, but pitched battles can't be avoided all the time. So let's use the secret weapon: scorpions!
Now the questions:
* is throwing scorpions realistic? I assume catching the scorpion's tail and then a sling-like throw. Or would you suggest any other technique? Is it something that ordinary tribesman (not ordinary civilized man like me or most of you) with some training can do, does it require specialists chosen for their dexterity, or is this feat risky even for the best ones?
* what scorpion species is ideal for this? It's fantasy, so we are not limited to Earth's species, but I don't assume our scorpions to be much different. They can be slightly bigger, perhaps with slightly different behavior (easier to tame), and their poison should be either a known real scorpion poison, or something other that makes sense (some of snake poisons?).
* as a shieldwall breaker, will it be as efficient as I think? I expect the thrown scorpions to get killed or at least to use all their poison in the rage just after landing, so unless the thrower gets killed or seriously injured before throwing the scorpions, they won't hinder our soldiers from crushing the enemy unit.
* how much efficient will it be against the armored enemies?
* is it as good "elephant spooker" as I thought?
In fact, I expect scorpion throwing to become obsolete after invention of some primitive Molotov cocktail few decades after the invasion, but I'm interested how useful it will be before that.
[Answer]
# A box full of scorpions
The first step is to wear apropriated gloves. Grabing a scorpion with your bare hand is dangerous, so you should use gloves to avoid being stinged and poisoned when handling them.
If it is a large bag or box with thousands of scorpions inside, most of them would poison their peers and other would be suffocated. Further, they would be hurted by the movements induced in the bag or box when the skirmisher is walking, running or fighting and be shaken and crushed around inside the bag. The result is that when the battle begins, most of the scorpions would already be dead or very injured and the progress of the battle just makes things worse. Further, even if they happen to survive and be in good health, the surviving ones would probably be moving frenetically in panic trying to leave the bag or box. Putting your hand inside a bag or a box full of living scorpions trying to escape in panic don't seems to be a good idea, even when wearing gloves. So clearly, a simple bag or box for carrying the scorpions won't do. The skirmishers would need to bring specially constructed bags or cages for the scorpions.
So, the scorpion tamers would need to have an special bag to carry the scorpions in the battle. Ideally, this bag would be a box designed to protect the scorpions from impacts, shakes and crushings induced by its wearer walking, running or fighting and also to protect each scoripon from each other scorpion. Also, the scorpions should not suffocate. This could be achieved by making it a rigid cage (so it would not deform significantly) with a cell-like, grid-like or beehive-like structure, where each scorpion is completely immobilized in its own cell. The cell is internally coated by some soft material. Further, each cell has a small hole to the outside to ensure air circulation and should be designed in a way that the skirmisher should be able to safely, easily and quickly release and grab the scorpion.
It would be something like the following picture:
[](https://i.stack.imgur.com/Lm02s.png)
The inner walls (pink) and the inner floor (yellow) would be made of some soft material to absorb impacts that could injure the scorpion (red). The front wall has a hole to ensure air circulation. You can see that the scorpion is immobilized by the gray wires that act like a seatbelt on them and restrain their movements. Also, the gray wires have some supports against the cell's floor to avoid crushing the scorpion. The wire are held firmly by the two blue scrows. This box is open in the top and the reason is because it would work like a matchbox. Each cell would really be two boxes, where the outer one has the bottom, top and the two lateral sides but is open in the front and back, while the inner box is open just at the top. With this design, to grab a scorpion, you just get the box, open it just like you would do with a matchbox, and grab the scorpion by getting its tail with your thumb and pointer fingers while bending and breaking the gray wires.
The size of the great box would depend on the number of cells present, and hence, the number of scorpions. Sometimes, larger boxes would be desired over small ones if the skirmishers would need to entrench or go into missions were they need to take a large number of scorpions. Sometimes, smaller boxes would be desired over larger ones because the skirmishers would need to go to battle in a way where saving weight is important and there is a cart full of scorpion boxes nearby. Also, some soldiers might personally prefer to work with smaller boxes while some others would prefer larger ones.
# Dexterity
Opening a matchbox is very easy to do. It would need some practice to appropriately grab the scorpion from the matchbox in just a few seconds without hurting it or accidentally dropping it on the ground or anything like that (and please, do not forget the gloves!) Anyway, **this is something that anyone can possibly master even with only a couple hours of training.**
# Throwing scorpions
Throwing scorpions with your bare hands is realistic only in a very few handful cases. Might be useful when there is a wall of shields marching towards your army. When they are close enough, your soldiers throws the scorpions over the shields, and immediatelly attack using whichever weapons they have in their hands, possibly running backwards to get a few more seconds in order to allow the scorpions sting the enemies.
Scorpions aren't very aerodynamic and will present a lot of air resistance when thrown out. With this, no one would likely be able to throw a scorpion farther than something like 5 to 8 meters. If you use a sling, you might be able to reach something like 10 meters. If you attach a small stone to the scorpion and throw the stone with the sling, you might reach 20 or maybe 30 meters, but this will likely also kill the scorpion.
Attaching it to a javelin that somehow release the attached scorpion or scorpions only when it hit the ground is probably more effective, since they might land softly enough to allow at least part of the scorpions survive the trip and then detach from the javelin to walk and sting around wherever they landed. This has the advantage that even if the enemies protect themselves with shields from the javelins, the released scorpions might end walking over the shields into the soldiers hands or fall into their heads, destroying their morale and making them shake and scream in panic instead.
For a hand grenade, it should be done of a material that absorves most of the impact while releasing the scorpions alive. I can't think of a material that have the right properties and not be something high-tech. The best that I can think is a ball of mud full of scorpions that would splat when hit the target with at least something like a third of the scorpions surviving. However it can't be prepared prior to the battle and stored because the scorpions would either die from suffocation inside the mud or escape, and this makes it completely unsuitable for any serious use as hand grenades.
Catapulting individual scorpions against an army is also likely to be useless. If you already have a catapult, then you would be better to simply throw stones instead. However catapulting a mud-grenade or a cow carcass full of scorpions over a wall in a siege might work as a way to frighten the enemy and luckly make some of them stinged.
It might be interesting in arrows. The scorpions could be already glued to arrow tips in their box by theirs stings, and then the archer would remove the arrow tip from its matchbox, break the scorpion tail in order to keep the sting in the arrow while removing the rest of the unaerodynamic scorpion from it, then attach the arrow tip to the rest of the arrow and throw it with the bow. The result would be a poisoned arrow.
Also, scorpions might be useful to be thrown at the enemy when defending a fortification or stronghold against battering rams or enemies trying to dig under your wall. Normally, rocks, or boiling water or oils would be better, but scorpions will be more effective against their morale.
# Which species?
Accordingly to [wikipedia](https://en.wikipedia.org/wiki/Scorpion#Sting_and_venom):
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> # Sting and venom.
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> All known scorpion species possess venom and use it primarily to kill or paralyze their prey so that it can be eaten. In general, it is fast-acting, allowing for effective prey capture. However, as a general rule they will kill their prey with brute force if they can, as opposed to using venom. It is also used as a defense against predators. The venom is a mixture of compounds (neurotoxins, enzyme inhibitors, etc.) each not only causing a different effect but possibly also targeting a specific animal. Each compound is made and stored in a pair of glandular sacs and is released in a quantity regulated by the scorpion itself. Of the 1,000+ known species of scorpion, only 25 have venom that is deadly to humans; most of those belong to the family [Buthidae](https://en.wikipedia.org/wiki/Buthidae) (including [*Leiurus quinquestriatus*](https://en.wikipedia.org/wiki/Leiurus_quinquestriatus), [*Hottentotta*](https://en.wikipedia.org/wiki/Hottentotta), [*Centruroides*](https://en.wikipedia.org/wiki/Centruroides) and [*Androctonus*](https://en.wikipedia.org/wiki/Androctonus)).
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If they are meant to be throw by javelins or grenades to survive the travel and sting someone, smaller species are preferable. If they should be very visible to the enemy to lower their morale, then larger, easily visible scorpions are better. Also, it is easier to handle larger scorpions than smaller ones.
For the larger scorpions, a [Deathstalker (*Leiurus quinquestriatus*)](https://en.wikipedia.org/wiki/Deathstalker) might be what you want, it is one of the most venomous scorpions and is large enough to be handled by your soldiers. [*Centruroides bicolor*](https://en.wikipedia.org/wiki/Centruroides_bicolor) might also be suitable since it is large (but the power of his venom is still poorly studied). [*Hottentotta tamulus*](https://en.wikipedia.org/wiki/Hottentotta_tamulus) is also deadly venomous. Also, they color are quite distinctive to fright the morale of the enemy. If you want something black for nightly attacks, try [*Androctonus bicolor*](https://en.wikipedia.org/wiki/Black_fat%E2%80%93tailed_scorpion).
Also, [see SeanR's comment](https://worldbuilding.stackexchange.com/questions/22660/scorpions-as-living-handgrenades/22666#comment65075_22666):
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> If I absolutely had to weaponise a scorpion, it would be [*Parabuthus transvaalicus*](http://www.ntnu.no/ub/scorpion-files/p_transvaalicus.php). Not the most potent but:
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> > "LD 50 value for this species is reported to be 4.25 mg/kg. Due to it size, this scorpion can inject very large amounts of venom. NB! This species is able to squirt venom up to one meter away, and venom in the eyes can be very dangerous."
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Also, [accordingly to wikipedia](https://en.wikipedia.org/wiki/Parabuthus_transvaalicus), *Parabuthus transvaalicus* has 90 to 110 millimeters, which makes it a big and black or dark brown scorpion. Very good for nightly actions!
For small scorpions to put on javelins and mudballs, sorry. I don't know which species would be suitable. [*Centruroides suffusus*](http://www.scorpionsetc.com/scorpions-what-is-truth-and-what-is-wrong.html) might be suitable. Many species are not well studied and small scorpions with 4 cm or less are easily overlooked even by biologists.
# Scorpions vs men and elephants
Scorpions work best against unarmored or lightly armored enemies. Against strongly armored enemies they are ineffective, except perhaps against their morale. They might work well with elephants, since their skin, although thick, [is sensible to insect bites](https://en.wikipedia.org/wiki/Elephant#Skin). However, a single scorpion will not kill an elephant because they are too big and massive for that, but they surely can be disturbed when stung.
This also means that your army would need to be enoughly armored to avoid that any accidental release means deaths and morale problems between your own men. Also, they should be trained about how to quickly kill escaping scorpions if needed and how to properly react if they let some scorpion accidentally escape.
# Taming
Overall, I don't think that using scorpions would be an effective tactic. The scorpion does not have enough brain to be trained to don't attack the tamer but attack anyone else. Also, as noted in Steve Bird's answer, scorpions that are less likely to attack the tamer would also be less likely to attack the enemies and even the most agressive species might chose to flee instead of attack. Also, since you would need thousands and thousands of scorpions, taming then one by one would be expensive. So, the best is to farm an agressive and venomous specie and delivery them immobilized and untammed in the matchboxes.
[Answer]
A few considerations that leap to mind;
1. A scorpion wouldn't be very aerodynamic and so a thrown scorpion would have limited range (especially compared to a longbow or crossbow). Even if you employed a mechanical device to aid launching (sling, scorpion ballista, etc), it's not going to have the same range as an arrow or crossbow bolt. So you're going to lose in a ranged weapons exchange.
2. Using too much force in the throw could kill the scorpion rendering it useless (espcially if it hit a shield or armor).
3. Docile scorpions (re: easier to tame) that are less likely to sting their handlers would also be less likely to sting their intended targets.
4. Even more aggressive scorpions would not necessarily choose to sting the person they were thrown at but might just flee instead.
5. To be effective battlefield weapons the scorpion venom would need to be fatal (or at least incapacitating) fairly rapidly. If it takes several hours or days to take effect, the battle may be lost before it happens.
6. Since the scorpions are effectively a "use it and lose it" weapon, there would need to be hundreds (if not thousands) of them available for each battle.
7. Finally, a thrown scorpion wouldn't really be like a "handgrenade", which could kill/incapacitate multiple targets at once. It would actually be less effective than a poisoned arrow (which would be easier to handle, have greater range and could kill even without the poison taking effect).
While being hit by a scorpion shower might have a "what the..?" effect on those on the receiving end, I'm doubtful that it would be a battle winner in anything but very contrived circumstances.
[Answer]
Scorpions should be placed in fired clay containers and catapulted into the masses of enemy infantry or in front of the cavalry as they are forming up.
Because scorpions are very anti social, carrying masses in a bag or box will result in most of them killing each other, so either each soldier has a small box or bottle holding one scorpion apiece (then dropping it into the catapult "shell" just before firing), or some sort of specialized container for carrying multiple scorpions at once (as per Victor Stafusa's answer), and then loaded into the catapult "shell".
The shell, being brittle, will shatter into fragments on impact, and (especially against unarmoured opponents) be a threat in of itself, so the solders will likely crouch behind their shields to protect against razor sharp fragments flying around. The ground becomes littered with angry scorpions, who are now likely to sting the feet and ankles of the solders and the lower legs of horses and elephants. People and animals fleeing the stinging scorpions will break the cohesion of the enemy lines, and attacking an unorganized mob will be much easier than a solid shield wall or organized force of soldiers and cavalry. You won't want to charge right into the fleeing force, since you will run right into the scorpions, but flanking units attempting to swing around the sides and into the rear area can attack the fleeing forces, collapsing their moral and preventing them from reforming.
The armoured force you suggest will be far less affected by scorpions. Unless they do not wear boots or footgear, the armoured infantry and cavalry will be mostly immune to the stinging scorpions when in battle array or in marching order. The best way to use scorpions to attack them would be to somehow sneak small catapults close to their camps at night and fire scorpion "shells" into the camps, where the enemy are more likely to have stripped off their armour and other protection. Even in the morning, many casualties might be cased because scorpions have scuttled into the boots of the remaining enemy soldiers.
[Answer]
**C**altrop **C**atapult **C**arpet.
* The defenders, who are expert scorpion handlers, could first of all simply throw the scorpions to create a scorpion-caltrop carpet. This would be devastating to barefoot attackers.
* Later they would develop hand catapults to increase their range.
* Next, they could progress to a large mechanical catapult that fires many scorpions at once.
* Then they realise the advantage of using bow and arrow. Initially they simply replace the arrowheads with severed scorpion tails that are tightly bound in place with twine.
* Finally, they realise they can extract the poison and simply dip ordinary arrow heads into it.
[Answer]
If you are looking for scorpions as a psychological formation breaking tactic and as a way to deal with armor, I would say that it isn't the poison that is important, but the piercing strength of the tail. In a fantasy setting, you could make them be bred to exhibit extremely strong tail motions, enough to pierce through armor. Perhaps their bodies are covered in a carapace that allows them to survive the toss, and efficiently sink their legs into the armor.
This idea is super cool, and one idea that seemed interesting was a calming oil; you could calm them, position them into a straight, laid out position, and then aerodynamically fire them over the shields and into the centers of the formations.
[Answer]
It's that I don't have enough points for a normal comment but I'll give it my best anyway.
Okay so I'll establish first what kind of scorpions you might want. I think you'll want small scorpions with large stingers, with a relatively social behavior atleast to the degree of that of snakes that can all sit together in a small pit (you could probably breed for this and it also makes breeding easier), that have a type of poison that works on the nervous system. There are generally 2 types of poison: poison that effects the blood, which is anti-clothing and works relatively slow, and poison that works on the nervous system, shutting down communication to vital organs like heart, lungs, brains and etc and can take effect in a matter of minutes.
Would you be able to throw certainly.
However I think that throwing by the stinger like you said might be a little risky and ineffective as well.
What would be more effective would be throw a container of scorpions that breaks on impact. This way you could fling multiple scorpions with minimal risk.
You correctly mentioned slings, which to my knowledge where indeed used by Egyptions or at least by other African tribes around that area and in the era. (there where slingusers in Hannibals army when he fought the romans)
Something was used a lot during sieges were stafslings, to throw flaming pots of oils, which throw further and more accurate than a normal sling and can also have a heavier load.
So you could place a bunch of scorpion a big pot and fling it at the opponent, because like insects scorpions probably won't die from falling damage you could even have a second expert slinger shoot the pot with a stone to scatter the scorpions so they rain down on the enemy.
I think this would be far more effective than for exemple use them as crawling caltrops, because if it rains down form above they might land in places that aren't easy to get to, in their clothes (think how panicked people get if they think that there's a spider or bug is in their clothes, much less a scorpion, now think of how their erratic movement will mess-up formations or chaotic it will get) in their hair and those that don't land on a soldier are still crawling calltrops. Where as if you only throw them as calltrops which is just far less demanding you pay attention to multiple angles of incoming attacks. (although testudo likes shields to protect them from the worst scorpion rains might make it a bit less effective or if they use sheets of linen to catch and throw them back)
You could also do what modern snake catchers do with snakes in bags and use a sheet of linen where drops a few buckets (A bucket should be something that is readily available, sturdy, safer to handle for the person carrying it (that person and or the people holding the sheet don't necessarily have to be scorpion experts) and can be loaded from the scorpion farms prior to the battle by the handler) of scorpions in and then the two people holding the sheet pull really hard on the tips and launch the scorpions several meters high and far into the enemy lines. (to avoid any stragglers caught in the sheet and fling that at them. you could even have soaked it previously in some kind of flameble oil, that calms the scorpions and makes the sheet more slippery, making it easier to launch without to many stragglers and they won't climb out that easily. Light a piece of cloth that is sewed onto the sheet on fire and fling it at the enemy. Now you don't have any
friendly (scorpion) fire and they have a flaming cloth to deal with. (if it landed on someones head for example))
You could make the scorpion staffslingers the more longrange damage dealers to effect the deeper lines in the enemy forces (the frontline might get distracted and even if they aren't they don't any back-up from behind, so if the first lines fail you can far further than you would otherwise) and the scorpion sheet-thrower from more in the front.
To either have to go to the front and throw their payload and then retreat back (like the velites did) or from like the 2nd or 3th row (for the sake of safety), I think this would go really great with something like a fallanx or cavalry that has horse that kind look down.
SO YES IT SHOULD BE VERY EFFECTIVE, against tight formation.
The effectiveness on armored opponents depends on how many openings they still have.
What kind of ''heavy armor do they wear, plate armor, scale , lamelar or something else like brigandine perhaps. It's hard to say, but no matter what armor I'm wearing if there's a scorpion on my shoulder it's going to effect me mentally.
I would they would be pretty spooked by them, but I think if you want to spook elephants bees are better.
There's a Korean movie about a castle sieges where defending forces used bees (it's during their Three kingdom period)
You could sling pots with honey-flued onto the elephants and than release the bees. this would give you a directed retreat and mean that the elephants mostly or only trample the opponent. <https://kids.mongabay.com/facts/2015/05/16/what-are-elephants-really-scared-of/>
Lastly if this seems cruel to the animal, maybe it is, but it was rather normal in old times and animals weren't exactly cuddled back then, the romans used flaming piggs!
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Biotechnology is a big keyword in the industry right now, like computing was a bunch of years ago. Nowadays, anyone can pop up a terminal and start tinkering with their computer, program software, make anything from their imagination true in the virtual world. A similar trend is observable with objects and the growth of fab labs all over the world.
Will this happen with biology and how soon? At what point in our near future will we see kids play with molecules and DNA and life?
This question is NOT meant to encompass what such tinkering might result in.
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Although my answer is surely opinion-based, I think the answer is: probably never. The reason is, that if you would like to compare human and animal genetic code to a computer code, it would look like 0 % of logic and structure and hundreds of millions years of debugging. This is how evolution works: random mutations are created and if they are useful, they spread. Computer programming can also by done this way with use of [genetic algorithms](http://en.wikipedia.org/wiki/Genetic_algorithm). The results are often effective, but completely incomprehensible to humans.
Already today, we can insert almost any DNA we wish into a cell. One could write DNA as a long series of letters and we would be able to synthesize it. The problem is not in the technology, but that we do not know what it will do. Since it is so hard to understand the DNA code, fine changes will probably always require extensive amount of research and experiments. The code is just too messy to change it so simply.
If all animals are "very poorly written", we might ask how close are we to writing animals from scratch. It also seems very, very problematic. Unlike life, our software is very hierarchic. Higher level of programming relies on precise translation into assembler-like processor instructions, which rely on processors performing very precisely many simple tasks. Even processor is basically a simple part - transistor - copied many many times into very precise structure. Each level works perfectly and can be completely separated from the next. This allows us to understand it and write software efficiently. Basic units of life - proteins, are much more messy. They do not by any way work so cleanly as transistors and one probably needs much more trials and errors to persuade the whole machinery of proteins to work as intended, cooperating with other proteins. My estimate is that we could still need hundreds of years to find a way around it.
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The question is really hard to answer, because of [stem cell controversy](http://en.wikipedia.org/wiki/Stem_cell_controversy) wherepeople of religion object against using human embryos for purpose of science.
Even though you left out the thinking about end results of everyone being able to play around with live organisms, the real spread will be built around of "what possibilities does this bring us"
For instance, while it holds true that you are able to buy computer and write your first [Hello World](http://en.wikipedia.org/wiki/List_of_Hello_world_program_examples) program, in case of "lab science" it is still sufficient enough to let you do little lab play with discovering flower cells and if you feel like want to know more, there is specialised school to learn you that.
Also, computer in every household appears because it solves more than one problem of "general household" (while "playing games" might be one of them).
Long story short, even if the general public is supporting strongly the DNA tinkering, I still believe that device to play around with DNA will be part rather of "high school lab" than common household. (So, it will never reach common household).
To guess the time, I think plausible horisont to think of is 20 to 50 years.
But keep in mind, that no matter how cool the device or technology may sound on the paper, always the general public may [be against it](http://en.wikipedia.org/wiki/Google_Glass).
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It will not be long before we choose to use the power of DNA and biology to help us do computations (DNA based computers exist today). However, it will be a LONG time before we are comfortable mucking with existing biology because the "source code" is just too mind-numbingly difficult to understand.
We've been evolving for millions of years. "Readability of the genome" has never once been selected for (in fact, it might have even been selected against). All human code written has had "readability" as a major concern, so we design our products differently. For example, there is a meme in programming "goto considered harmful," because it makes things hard to read. There's also a philosophy to do minimize thread interactions because they are hard to follow. Nature's product uses "goto" everywhere, and the best analogy for cellular behavior would involve millions of interacting threads. Many of our quirky shapes and features are actually a result of "shared code" which mutated to be beneficial for a completely different purpose.
I like to believe we will have some power over biology at some point in our race's future. However, I do not believe that power will have a strong resemblance to today's programming. I expect it will look far more subtle.
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Genetic engineering technology already allows us to manipulate the genomes of several model organisms with extreme precision. Homologous recombination in yeast enables researcher's to change virtually any sequence in the genome to whatever they want, and now the CRISPR/Cas9 system being developed shows enormous promise for use in more complicated multicellular organisms. Current genetic research commonly involves deleting DNA sequences, inserting DNA sequences, fusing genes together, and really anything you can imagine doing to a genetic sequence to figure out how it works. Now that isn't to say it's easy. There are time-consuming precise protocols that have to be followed that don't always work. It takes the resources of a modern lab, a fair amount of money, and a lot of expertise. For a kid to ever be able to do it the entire process would need to be automated by a machine. Some extremely well-funded labs have robotics that are capable of automating some processes, but we are a long way off from some sort of all-in-one genetic engineering personal device.
While it may be possible in the future to quickly and cheaply manipulate the genome of an organism, the larger barrier to actually making something you want is knowing what to change. We really don't understand the purpose of most of DNA in our genomes. Our current research typically involves breaking something, seeing what happens, and then coming up with a model for what that thing was doing. We are a long way off from being able to make purposeful changes to generate custom organisms.
In my opinion the biotech revolution you envision will likely need to be proceeded by a computing revolution. To actually get a complete model of how genomes work we need powerful computational models for protein structure and function prediction as well as for simulating all of the interconnected regulatory networks governing all of these proteins.
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100,000 years from now? 1,000,000,000 years from now? Never?
There are many arguments against this ever happening, and even more arguments why this will never happen any time soon, unless we invoke science fantasy and also rapid moves towards utopian social improvements at the rate of, say, the *Star* *Trek* timeline. AFAIK *Star Trek* doesn't have this level of technology (nor of childhood trust).
Consider:
* **Messing with your body is dangerous** so until and unless we also have resurrection technology, it would be irresponsible to invite the general public to play with genetic manipulation.
* **Genetic manipulation is dangerous to all life** especially since in order to change an organism's DNA in a systematic way, it needs a powerful spreading mechanism, and DNA also naturally mutates. This is why it is a very bad idea to let for-profit corporations actually release GMO crops, let alone to feed them to everyone, and to not label them. For example, GMO plants spread their seeds into the environment where they end up spreading into other fields and corrupting them into GMO plants and new GMO varieties, reducing non-GMO plants. When these companies also intentionally design food crops to not be able to generate seed, to contain massive pesticide levels, etc, they're just asking for something to go wrong, potentially irreversibly. Letting Junior mess with DNA is a bad idea, and your future society is going to have a bad time.
* **The analogy that DNA is like program code is theoretical and metaphorical more than it is literal and practical.** Messing with DNA in seeds until you get some positive effects is the programming equivalent of randomly playing with someone else's machine code, like this:
Except THAT is a very concise, logically-written and small program, so something with massive number of pages of that, and written randomly by nature, with most of the code apparently doing nothing but possibly doing something, and no linear execution, since some of it may be the part (or part of a part of a part of a system) that starts having George Lemuelson's chin hair turn grey at age 48 while reducing his libido 5%, and increasing his chance of gaining diabetes-A by 5%. And you can only cut and paste it in chunks, exchanging chunks from other versions of the same program. Your only hope is that the chunks you have to cut and paste come from other programs which have been designed to be cut & pasted and recombined. But unfortunately, many of these combinations may be infertile or lethal or cancerous, which is why GMO is done in labs where you can throw away almost all of your many many failures. Which you don't want Junior doing on himself, unless you want him to die.
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I want to have an upper atmosphere composed of a gas which is lighter than "air" so that my human occupants of a planet can harvest it and use it to fill blimps and hot air balloons.
I'm planning on having my "normal air" as Nitrogen Oxygen as I see no need to change it from Earth-like. I'd rather not use have a Hydrogen layer (as it explodes and would ignite both balloon and planet).
Is it possible to have a layer of Helium in a planet's upper atmosphere (which then the humans could use some dodgy hydrogen balloons to reach and harvest).
If not Helium what other gases are viable?
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There are three problems with a lightweight upper atmosphere.
1. There aren't that many lightweight gases. Off the top of my head, your options for lighter-than-nitrogen/oxygen (molecular weight 29) are neon (MW: 20), hydrogen fluoride (MW: 20), methane (MW: 16), ammonia (MW: 17), water vapor (MW: 18), helium (MW: 4), and hydrogen (MW: 2). Of these, methane and hydrogen are flammable, water vapor will tend to condense, ammonia is toxic, and hydrogen fluoride is highly reactive. For the purposes of ballooning, a mid-weight gas like neon has only half the lifting power of hydrogen or helium.
2. A lightweight upper atmosphere will tend to escape into space. With hydrogen and helium in particular, a sizable fraction of the molecules at upper-atmosphere temperatures will have velocities above escape velocity. Something heavier like neon or ammonia will tend to stick around, but will run into problem 3:
3. The atmosphere is pretty well mixed. An exceptionally lightweight gas like hydrogen or helium will be noticeably more abundant in the upper atmosphere, but will tend to escape. Mid-weight gases like neon, on the other hand, will be mixed in by ordinary atmospheric circulation.
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Helium is the obvious candidate, it's only slightly heavier than hydrogen. It's not flammable or explosive, and it works well in balloons.
There are three fundamental problems though which makes the idea unrealistic:
**Where does it come from**
Where would all that helium come from? The chemical makeup of the planet would be very different from our own.
**Why does it stay separate**
You would expect atmospheric mixing to constantly churn the atmosphere. Oxygen, Nitrogen and Carbon Dioxide all have very different densities but they still mix fairly evenly in our atmosphere.
**Why doesn't it escape into space**
Lighter gasses escape more easily, you would expect Hydrogen and Helium (especially in the upper atmosphere) to be stripped away into space by atmospheric escape.
***A possible solution***
There is one scenario that might just work although it's still rather implausible. That is if the planet was a moon in low orbit around a gas giant. The gas giant would be the source of the helium and hydrogen, replenishing that which was lost and causing escaped gas to remain in a ring to be gathered in again as the moon orbits.
That doesn't solve the atmospheric mixing problem but you can hand-wave that to a certain extent.
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You can get past the problem of He escaping into space only if the planet's core is rich in radioactive isotopes that undergo alpha decay. That would produce a supply of He to replenish what's lost to space.
Then you might actually have, instead of an upper-atmosphere layer, certain mineshafts that go deep enough to tap into this natural source of He.
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My story has vampires in it. Within my story's universe, I want a human kissing one mouth-to-mouth to result in [nitrogen narcosis](https://en.wikipedia.org/wiki/Nitrogen_narcosis)-like symptoms for said human, and for said symptoms to intensify as long as the kiss is maintained.
For reference: nitrogen narcosis is caused by inhaling [nitrogen](https://en.wikipedia.org/wiki/Nitrogen) gas at a high pressure. As the pressure increases, the victim - among several other symptoms - slowly looses their consciousness and ability to think clearly, up until they pass out and/or die.
Unfortunately, nitrogen narcosis won't work as an explanation for this, since I want to write a *somewhat* biologically plausible vampire. A form of life that's...
* compatible with Earthly biology
*and*
* contains nitrogen gas under many [atmospheres](https://en.wikipedia.org/wiki/Standard_atmosphere_(unit)) of pressure - for instance, [to be lethal, the nitrogen gas's pressure has to exceed at least 10 atmospheres](https://en.wikipedia.org/wiki/Nitrogen_narcosis#Signs_and_symptoms) -
...doesn't seem remotely (let alone "somewhat") plausible to me. Moreover, I don't think releasing a gas at 10 atmospheres of pressure within kissing range of a human - and doing under sea-level atmospheric conditions - would be safe for said human.
**What biological mechanism would cause a kiss with a vampire to - as long as the kiss is held - slowly afflict the other participant with symptoms of nitrogen narcosis, and how can such a thing work without being incompatible with Earthly biology?**
**The nitrogen narcosis-like effect needs to wear off over a week at most and half a minute at least.**
Acceptable answers can be anything that could possibly exist within the limits of Earth-based biochemistry, but please don't make ones based on non-biological technology or magic - these vampires were bioengineered, not cybernetically altered or summoned from Hell.
* *Good* answers will be biologically plausible, or at least not cite things like "magical knockout gas".
* *Better* answers will cite a specific biological mechanism, and why the answerer believes said mechanism will mimic the effects of nitrogen narcosis.
* The *best* answers will do all of the above, as well as specifically explain the [pathophysiology](https://en.wikipedia.org/wiki/Pathophysiology) of how their mechanism slowly shuts down the human brain. For instance, such an explanation for nitrogen narcosis would state that it
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> appears to be the direct effect of gas dissolving into nerve membranes
> and causing temporary disruption in nerve transmissions.
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[Answer]
Just use a regular biological toxin.
There's no reason to get overwhelmed with trying to work specific elements like nitrogen gas into the vampire's biology when all you need is a regular old neurotoxin that has the same effects. The world is filled with animals, plants, and fungi with nerve-affecting properties, from opiates to hallucinogens, and any of those could plausibly develop in a living creature, since they already did.
The biggest question is how such an effect would evolve, but it makes sense for a vampire (who feeds on living blood) to produce a toxin that can render their prey dazed without killing them. It could have started as a simple pain-blocker (vampire bats and mosquitoes both produce pain-dulling chemicals in their saliva so their sleeping prey doesn't react when they are bitten), similar to opium which works by blocking nerve transmissions.
If that nerve blocker becomes stronger, it could develop into a toxin that slows down the entire nervous system, first helping to keep its sleeping prey asleep, and later increasing to the point where it could render prey dazed even when awake. This could evolve into the practice of maintaining control over a herd of human "cattle" and feed off of each one a small amount without killing them (and being forced to find new prey). Opiates are also addictive, which would certainly be beneficial for vampires that use them for this purpose.
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There's a whole range of [NMDA receptor antagonist](https://en.wikipedia.org/wiki/NMDA_receptor_antagonist) chemicals out there, which cover a number of anaesthetics which are known to induce a [dissociative state](https://en.wikipedia.org/wiki/Dissociative).
These have a whole range of effects, some of which are enjoyable and lead to recreational use of some of these pharmaceuticals (such as ketamine) but perhaps most usefully for predatory purposes:
* [Ataxia](https://en.wikipedia.org/wiki/Ataxia) and [catalepsy](https://en.wikipedia.org/wiki/Catalepsy), interfering with voluntary muscle control and co-ordination.
* Confusion, memory and cognitive impairment and amnesia.
* [Derealization](https://en.wikipedia.org/wiki/Derealization), where the world and events in seem to be come separated or unreal.
* Analgesia and unconsciousness.
This combination of a euphoric high, loss of muscle co-ordination and a general unwillingness or inability to fight back followed by the possibility of being unable to remember what happened at all seems ideal for vampirism purposes.
Whilst L.Dutch's suggestion of nitrous oxide is an NMDA receptor antagonist (and was in fact my first thought of how to answer this question, but I was too slow, so L.Dutch got my +1 instead) there are others which are much stronger with much more pronounced effects. People on high-dose nitrous might giggle a lot and forget what they're doing but the effects are shallow and quickly shrugged off and memory effects are limited or absent. By comparison, someone deep in the [k-hole](https://www.healthline.com/health/k-hole#what-it-feels-like) isn't going to be shrugging *anything* off for some time.
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Your vampires might be exhaling [nitrous oxide](https://en.wikipedia.org/wiki/Nitrous_oxide#Recreational_use) (aka laughing gas) during the kiss.
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> Recreational inhalation of nitrous oxide, with the purpose of causing euphoria and/or slight hallucinations, began as a phenomenon for the British upper class in 1799, known as "laughing gas parties".
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> Starting in the nineteenth century, widespread availability of the gas for medical and culinary purposes allowed the recreational use to expand greatly throughout the world. In the United Kingdom, as of 2014, nitrous oxide was estimated to be used by almost half a million young people at nightspots, festivals and parties.
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In this way the more the kissed one is kissed, the more becomes intoxicated.
Note that at higher doses the gas acts as an analgesic, which might be a good thing for a vampire wanting to have lunch.
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I'm putting together a homebrew adventure for a space horror game (using the Aliens RPG ruleset) and I was thinking about what a world with Mars like mass and lack of volcanic activity and ozone layer be like at a Venus like distance from the sun. Would/could such a world still have the very thin Martian atmosphere? Given such a thin atmosphere and a close sun would it be right to think there would be a great difference in night to day temperature, especially if the planet had an Earth-like period of rotation? Would this drive a very stormy climate (of course the thin atmosphere might make this quite different to storms on Earth)? What other features should there be on such a world?
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A Mars-like planet orbiting at a Venus-like distance would very likely be quickly stripped off most of its thin atmosphere by the solar wind and the lack of magnetic field, resulting in an even thinner one.
As a result, temperature differences between day and night could be quite extreme, somewhere in between what we have on Moon and Mercury: the thinner the atmosphere, the less buffering capacity it can offer.
I also think that, due to the very low mass involved in the atmosphere, its capability of storing energy would be low, and therefore the weather phenomena resulting from this stored energy wouldn't be particularly impressive.
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> Would/could such a world still have the very thin Martian atmosphere?
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It could. The trick is to balance out the timescales of things... as L.Dutch observed, the absence of a magnetosphere is bad news for atmospheres, but that's fine because you can set your adventure at the correct time period where any planetary magnetic field has reduced and the solar wind and radiation pressure has largely stripped the atmosphere away. This might involve a younger star and planet, but it can still be made to work.
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> Given such a thin atmosphere and a close sun would it be right to think there would be a great difference in night to day temperature, especially if the planet had an Earth-like period of rotation?
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There'll be a big difference, but it is hard to say what.
The [planetary equilibrium temperature](https://en.wikipedia.org/wiki/Planetary_equilibrium_temperature) would be something like 318K. Mars has temperature variations of the order of 50K, but it is a long way from the Sun... our Moon, by comparison, has temperature variations of more like 200K from midnight to midday, but has a very long day.
A variation of ~100K coldest-to-hottest would put the ambient temperature at the boiling point of water at midday. That's a pretty hostile desert world right there, and it might be underestimating how hot things could get... the equator would likely get much hotter, for example.
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> Would this drive a very stormy climate (of course the thin atmosphere might make this quite different to storms on Earth)?
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I wonder if there would be enough energy to have near continuous dust storms. They'd spoil the view, but they might reduce the scorching daytime temperatures and provide a way to distribute heat-energy to the cold side.
Omnipresent ultrafine dust would play absolute havoc with any mechanical systems, and seals likely wouldn't be able to keep the stuff out. It'll end up everywhere, including in the lungs and bloodstream of anyone living there, because there's no practical way to keep it out if you're ever cycling airlocks or changing in to/out of a spacesuit. Better hope it isn't toxic (which it probably will be!).
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Too many to list. Such an open-ended request is far too broad, and effectively unanswerable on a site like this. Ask for something more specific.
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There are a lot of sub questions here which I will try to address.
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Would/could such a world still have the very thin Martian atmosphere?
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It could, and this would result in significant temperature differences.
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Would this drive a very stormy climate (of course the thin atmosphere might make this quite different to storms on Earth)?
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I would not expect it to. On planets with thick atmospheres like Neptune and Jupiter we see long lasting storms, less so on thin atmosphere planets like Mars. Even though the temperature might be different there will be energy exchange, but it won't have enough mass to cause damage like an earth storm. More like moving dust and clouds, but no tearing up trees.
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What other features should there be on such a world?
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If has a thing atmosphere and no magnetosphere I would expect it to be not only hot, but radioactive because of cosmic rays during the day, while brutally cold at night. Also with so much electrical interference, without an earth like magnetosphere most electronics would be useless, during the day, without special magnetic shielding or Faraday caging.
If it has a thick atmosphere it would need the magnetosphere to protect it, but that is what would cause the intense storms. If the atmosphere was thicker we could see this play out as storms build up much slower and take much longer to subside. Think a hurricane that takes a week to get up to 7 mph winds, but the wind is almost as thick as water and makes it incredibly hard to travel safely.
Also it is worth mentioning that most planets closer to the sun have much longer days (Venus takes 118 earth days to rotate). You might want to provide explanation or at least mention that it is unusual for a planet to have such a short day so close to its star.
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So I have a species that has a life expectancy about half that of humans. In antique times, they mostly die around the age of 30 once they’ve passed the challenges of childhood. Their development is halved as well. It turns out they’re also about half the height of humans. *True halflings in a way*.
They live on a planet which is basically earth but slightly hotter (think just before the Eocene-oligocene glacial), not that I think it matters much.
I’ve not planned on having them breed seasonally. They have an œstrus cycle around 38-40 days.
**How likely is it that they developed complex civilisation?** They’re still at the Bronze Age, I accounted for about as many generation as humans from the development of fire and basic tools (which was influenced by a creator species which then disappeared and left them alone).
I remember reading about how shorter lifespans would make it difficult for any kind of civilisation because of the lack of specialists, but in the end they are fully mature around the age of 10 or 12 (as opposed to our 20) which still leaves them around 20 years to develop mastery.
Is there any major challenges you can think of? I could not find any in about an hour of research. The most I could find was the difference of mindset in long-lived species like elves as opposed to humans.
Note they are also mostly matrilineal and matriarchal. I had initially designed women as bigger and more of the fighting type although I question that but they are definitely the leaders.
I always, however, come back to the issue of dramatic drops in childbirth if women were fighters.
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The major obstacle to civilization is the loss of knowledge and the relentless need to transmit it. Basically, they will have to do it at double human speed in order to accumulate enough knowledge for civilization. *The Secret of Our Success* by Joseph Henrich details many cases where humans have lost technologies of vast importance to their cultures because of the loss of their practitioners.
So if they are to develop civilization, they need better ways to save and transmit knowledge. They need to learn quickly, have few obstacles to teaching others, and ideally, easy ways to record knowledge so it can be relearned. A social structure that does not support guilds, trade secrets, or other ways of keeping knowledge private (where it can be more easily lost).
Note that this can easily play in the matriarchal structure -- women don't fight, live longer, and know more.
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I think such a species is definitely possible, however the rate of development would probably be a lot slower than it is here on Earth. With such a short lifetime they might be less willing to spend as many years studying as we do. The might also be more impulsive, restless and impatient than we are (on average).
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[Neanderthal](https://en.wikipedia.org/wiki/Neanderthal) had average lifespan of 20 years, early Homo Sapiens had around 30 years, even modern human had average lifespan of around 30-40 years in medieval time. I think your civilisation probably reach Medieval Feudal level with nearly same speed like human civilisation, but it will be much harder for them to advance, because it requires practice - [Malcolm Gladwell](https://en.wikipedia.org/wiki/Outliers_(book)) said you need at least 10.000 hours of practice to achive perfect result in anything. If your "halfing" works 40 hours per week, it will took him/her 10.000/40 = 250 weeks / ~5 years to advance to perfect results.
Its unlikely, they will desire to spend 1/6 of their live on practice...
So, i think your halfing civilisation will reach Early Feudal level, with few Newton grade geniuses occasionally pushing them forward.
But, if their short lifespan is result of malnutrition and diseases, and it can be prolonged with proper food and medical assistance (at least to 50-60 years), they will probably advance as fast as humans do.
Also, if your civilisation respects book writers and do not burn books like various nazis do, it will be easier for them to learn and pass knowledge between generations.
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This reminds me of the [Salarians](https://masseffect.fandom.com/wiki/Salarian) from the Mass Effect franchise.
They have a lifespan of 30-40 years, which they make up for with high intelligence, very high metabolic rate, low sleeping time requirements and an extremely driven mindset, which results in them being the most technologically advanced species in the franchise.
Basically they live shorter but also way faster than humans.
The point is, since you have full control over the attributes of your species, you can equip them with the necessary attributes to do what you want. Intelligence, sleeping time, metabolic rate, as mentioned above are all very simple solutions to compensate or even overcompensate for a short lifespan.
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Yes, I do believe it is scientifically possible. On average, larger animals live longer than small animals, for example the bowhead whale can live up to 200 years old, while a cat can live up to sixteen years. The cause for this, I believe, often has something to do with metabolic rates. Smaller animals usually have higher metabolic rates, while larger animals have slower ones. Because of this they reach maturity at different rates, which affects their lifespan. And in many animals, it makes sense that they would not live very long after they are unable to mate. The point of a species, from my understanding, is to survive, and there isn't much else to it. Making them smaller would definitely make a shorter lifespan realistic, though I would like to point out that having an in-universe justification for their small size might make them a bit more realistic. Finding an outside reason why it is better for their species to remain small instead of growing to the height of humans might better solidify them, but of course that's just my opinion and definitely not necessary.
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What would be the psychological effects of a sentient creature having its central nervous system distributed throughout its entire central body? How would they think differently than humans? This seems like there could be some very interesting consequences that would stem from it, but I don't know what they would be. The only thought I have is faster reflexes but slower complex problem-solving.
I'm actually using this for a game of Pokemon Tabletop United for the tentacool/tentacruel line. Other psychological changes that I'm using are that they primarily rely on their senses of smell and touch, while vision is used almost exclusively for locating opponents in battle and communication since they communicate by flashing light from the orbs on their bodies. They also are primarily ambush predators.
I'm also open to other suggestions about psychological traits that could show up in them, but the above question is primarily what I'm looking for.
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Well the best real life comparisons we have to a less centralized nervous system are cephalopods (focusing on the octopus) and arthropods (other animals also have less centralized nerve distribution, like worms and jellyfish, but I don't find them good examples for a sentient creature).
So let's start with what we know about these creatures. Octopuses might be the best arrangement according to what I understood you want. They do have a centralized brain, but about 3/5 to 2/3 of all of their nerves are located in their arms. This, combined with the fact that each arm has hundreds of sucker pads capable of taste and smell, as well as their different "wiring" (octopus react to stimuli via behavioral patterns while we react via mechanical patterns), we have a creature which works normally as a single organism, with 8 arms that are basically capable of self-decision (severed tentacles have been shown to capture food and try to take it to where the mouth was). By this arrangement, we'd likely see a scenario in which the person doesn't need as big of a skull, but apparently will be capable of functioning essentially like a normal human, except this person might normally move around a bit more, letting their arms feel around for food and then shoving it into their mouths while they're talking to you as if nothing was happening, or reach their limbs out to feel your face should their owner not issue a command to stop and stand still.
Regarding faster reflexes, you'd e more or less correct, as the person's limbs will act in a way similar to involuntary reflexes, taking decision by themselves. you'll likely pull your arm faster from something hot, and you'll be able to grab things faster, but I other than that, I see no major differences. Your brain will take the same time to process images or sounds, and you won't run any faster than you already do.
Now the arthropod nervous system: in addition to a main brain, arthropods have several ganglia, dividing the nervous functions among these. This is basically why many insects can survive long periods without a head, as they basically have several secondary brains, which were responsible for keeping the body running, still intact. Crudely saying it would work exactly the same for us, in this arrangement, I don't see an increase in reactive response, as you "basically" just took certain bits of your normal brain and relocated them to your spine, but, with proper medical assistance (gotta stop the bleeding), you might be able to outlast your own head.
So essentially I'd say you'd likely be more interested in the octopus version of a less centralized nervous system. Your limbs might react faster to stimuli and things like repeated stepping or moving your hands around will likely be much more common and even seen as normal, but otherwise I'd say you won't be that different from a normal person
Octopuses as they are can solve puzzles, use tools, are naturally curious and ingenious, get bored easily, seem to be able to hold grudges, and can remember people's faces and taste (I know what I typed), so maybe your sentient creature might be more curious and exploring, as well as getting bored more easily, but that might be more from your personal decision than a trait inherent to the way their nerves are distributed throughout their bodies.
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Ask this guy about their psychology, I don't know any doctor or psychiatrists who interrogated an octopus about their mental health.
Although cephalopod [intelligence](https://en.m.wikipedia.org/wiki/Cephalopod_intelligence) has been highly studied across the years, we do not know how to communicate with other animals therefore we can not assess their state of psychology. The only thing we know about their psyche is that like every other intelligent animal on earth, when forced into isolation they become more desperate and start socializing with other species. Just like humans with cats.
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There would be no difference.
Psychology is about consciousness, and as long as the being has only one identity, it's not relevant where it is physically located. If a nervous system component is controlling some organ or subsystem, it does so without being conscious itself, and possibly without allowing conscious control.
Humans have examples for it themselves:
Our gastrointestinal tract is controlled by the enteric nervous system (ENS), which is so much autonomous that it is even colloquially called "second brain".
There is no psychology of the colon. We can not even consciously control the muscles that produce the movements to transport the contents of the colon.
Also, our central nervous system is distributed, our brain consists of two parts that are connected by bundle of nerves. But out psychology is only about one person, even while we know the physical representation is separated in two locations. It's possible that we can be conscious in multiple locations, but only one at a time - that would not change anything.
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They would make more snap decisions and be less intelligent overall.
Your brain is made up out of hundreds of thousands of neurons all connected to each other. Especially early in your life but also later on the usage of these neurons will determine what happens to them. Barely used connections are cut, often used connections are accelerated and rewired to reduce the amount of neurons that process the information to the proper answer for efficiencies sake. This creates a unique brain, so unique that it defines everything we are. Even if I somehow swapped all my memories and preferences with yours, I would now have your brain paths to deal with and I would imediately get your character as that is simply how your brain functions and is wired.
Now extrapolate this to your beings. Even if they have the exact same amount of neurons, those neurons are further apart. The information of your balance organ now needs to be processed and instead of sending it to the cerebellum next door it has to send the same message a dozen time to each seperate neuron cluster operating an arm, leg, spine, hip, finger or whatever else. This increases the signal density needlessly and reduces the amount of signals you can send around, not even mentioning the extra time needed for this message to reach all extremities and be processed individually by each neuron cluster rather than just by one cerebellum cluster that does the operation once with less total neurons and then uses this for all extremities.
This counts for everything. More total processing power is required and less time is available as it already took longer to process. This means that the neuron clusters have to shortcut their way to the answer, and we already know this is possible during flight or fight responses. In emergency situations your brain stops taking as much time to process everything to save your life, but it also means your brain will make mistakes. People will run back the way they came as their brain knows that route, all those green "escape" signs stop having a meaning and take much longer to process. It can take minutes or even hours before your brain tells you "hey that sign over there is actually what I was looking for". And this type of short-cirquiting will be exactly what your beings will be doing more or less depending on how decentralized they are. Quick to respond, good choices in a natural environment but the moment they are out of their depth and have to strategize or anything they are screwed.
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I am pondering on a work whose main theme is 'consciousness is fundamentally at odds with life and how it works'. Consciousness, sentience, self-awareness etc. values the individual, the self, and the connections it makes, while life is fragile, frail, and cares more about statistics: the individual is disposable so long as there's many more of it.
Ideally, i would embody that dilemma on an intelligence that isn't rooted in life, directly or indirectly (so not a machine built from living creatures or their works), or at least not life in any form we'd deem recognisable or relevant.
Any inspirations?
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I've meet several times on internet with idea called **"Boltzmann brain"**.
The idea is around random fluctuation in thermodynamic equilibrium. From what I understand, there are constantly fluctuations on smallest scale of physic, string and similar stuff. Generally those changes are way to small to have any effect on "material world", aka things that in our size scale. But if you would have infinity amount of time, you would have infinity combinations of those fluctuations, that mean there is some combination that would lead to creation something material. This material thing could be anything allowed by physics laws, and we know that brains are allowed. So, there is chance that those fluctuations would create intact human brain with any memory you could imagine, and with that "consciousness, sentience, self-awareness etc.".
There is big chance I butchered something in my description, I'm no professional in those topics. Anyway, if you want any further read jump right in to [wikipedia](https://en.wikipedia.org/wiki/Boltzmann_brain) or SFIA [video](https://www.youtube.com/watch?v=GrK9EaQRp2I) on this topic.
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I have read somewhere (but I don't remember where, so cannot provide any reference) the idea about a sentient nebula.
Basically it all boils down to the sentiency emerging from the collective interaction of molecules and atomic species in a nebula in space, the same way as our sentiency emerges from the collective interactions of the neurons in our brain.
The interactions would happen via exchange of EM radiation, and considering the distances in a nebula would involve time scales so large that would make it hardly recognizable from sentient beings tuned on our time constant.
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You have consciousness without life by defining it that way.
Odd, but true. To really dig into this question we have to define what consciousness is. For most of us in our daily lives, we don't have to define it, merely identify it. We live in a world where very few things are conscious (typically only people are conscious, though some choose to describe it as something animals can have too).
Your challenge is that "consciousness" is a term which has *famously* defied being nailed down with a hard crisp definition for the last few thousand years. Your story gets to explore a concept of consciousness which is permitted without life.
One currently active solution to this would be the [Integrated Information Theory of Consciousness](https://en.wikipedia.org/wiki/Integrated_information_theory) (IIT). In IIT, consciousness is defined to be a gestalt thing borne from capabilities present in the whole which are not obvious from the sum of the parts. It looks at information processing capabilities and defines Φ, which is a function describing this capability from several points of view. They tie ΦMax, the maximum amount if information stored in this integrated way, to the concept of consciousness, defining ΦMax to be a measure of consciousness. If ΦMax is 0, then an object is completely unconscious. Any non-zero value is conscious to some extent. Some objects are more conscious than others. This definition makes it trivial to argue why humans have a high level of consciousness compared to, say, rocks. It also offers a way to compare the levels of consciousness of an AI built in silicon to the levels of consciousness in a human being.
Speaking from a purely philosophical point of view, I find a very common thread in people's definitions of consciousness involve a reduction to infinity or a circular argument. The [Aggripan trilemma](https://en.wikipedia.org/wiki/M%C3%BCnchhausen_trilemma) famously declared that all logical arguments must depend on at least one of:
* A "truth" that is not proven. In math and science we call these axioms. We're used to the idea that we don't prove everything. So used to it, in fact, that in physics we often forget that we're not proving details and arrive at the erroneous conclusion that something is *actually* proven, when it cannot possibly ever be.
* A circular argument. This is a "truth" which is only proven by first assuming that it is true.
* An infinite regression. This is when your smaller "truth" is only proven by assuming that a larger "truth" is also true. If you're familiar with mathematical induction, where we use f(n) to prove that something is true for f(n+1), an infinite regression is using f(n+1) to prove f(n).
I find that any theory of consciousness which tries to go prove things eventually comes across the latter two. That's not to say they're wrong, but our own concepts of logic tend to be founded on the assumption that we don't do those sorts of things.
You may be *very* interested in the story of the Positronic Man by Assimov, which got made into a movie called Bicentennial Man. Assimov took a different approach in that book, which is to have the robot in the story slowly demonstrate the behaviors associated with consciousness while asserting that it was, indeed, conscious.
Which, funnily, is exactly how humans declare themselves to be conscious to begin with.
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Neither sentience nor sapience is something that happens at random. It is a completely unnatural state. Having something that is *complex* is not enough.
Anybody who has looked at Artificial Intelligence can tell you this. It is very very difficult. And it breaks down at the slightest disturbance.
All known instances of sentience has come from life. Either evolved as part of life or designed by already smart humans.
You have tagged your question with magic. This gives you large room for saying "That's just how magic is". It would push the limits of suspension of disbelief for *some* readers, but most readers will probably just accept it.
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The fundamental function of consciousness is information processing. This sentence is significant because it talks about information so we define it.
*What is information?*
Information in its basest form is the answer to a yes or no question. Black or white, 0 or 1. But does the answer to a yes or no question exist if there is no physical substratum on which the question can be asked/answered? This is how I understand you question to be. You are asking that is consciousness possible without the human form and the quick answer to it is no, not capable of being experienced by anything anyway.
In other words, does a question exist if it's not written in paper? What about a mind? Awareness of the question predicates its existence, but at the same time, without a physical hard-drive or measurement or disturbance in the physical world, you cannot expect an answer from the same physical realm. It's like trying to use USD in Brazil, doesn't work but it doesn't invalidate it yet.
If consciousness is not in a human form without the human surface(skin) and human sensors(eyes, tongue etc), does it make sense to talk about a consciousness with humane properties without a human body? We enter the realm of the abstract. In abstract space, the most perfect circle exists, yet we know it's not possible to physically realise this circle the same way a thought exists in the superset of all thoughts that are possible to be thought about yet unless it pops into someone's human brain, it is not physically realized or become an object of awareness.
Human consciousness is strongly associated with the ego a person has built over the years. From object permanence to qualia associated with each wavelength of light, to the picture of their parents and pets, all of it plays a role in designing the lens through which the person is capable of seeing the world. If one really wants to let these go and enter in a state of pure consciousness, he must leave behind the physical markings too, because they are not required for consciousness. That includes memories, logic, and everything that was learned from the physical realm be returned to it.
Once that is done, the only consciousness that remains is that which is permitted by the laws of physics. Like a deep coma sleep where you are aware of the way your body is tumbling and handled yet you have no opinion about it or can do anything about it. You just observe that. When your body dies, the brain processes sustaining your consciousness cease too and now your consciousness is truly free from all kinds of physical contracts.
What would that look like? Again we can go back to our abstract space. We return to this space where the perfect circle exists too, but nobody ever knows what a perfect circle is. You might picture it in your head but if we were to print your thoughts, it would only give us an approximation of that circle. Your consciousness removed from everything physical is just like that circle. You cannot comprehend the infinite points in a circle, nor can you comprehend non-human consciousness.
You know there is a perfect chance that this is the only universe that is ever going to happen in all of eternity and that this universe well as might would have had all the perfect conditions to support life but yet, just by pure chance, every life starting chemical reaction somehow failed due to quantum accidents, just by pure statistical chance. If that was the case, then all consciousnesses would still remain in the abstract space and all questions and answers would still remain too. But if you don't write information in a universe or in a piece of paper can it really need an answer in writing?
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The old books say, consciousness comes from god and is equivalent to our soul. Because consciousness is not attached physically to the body when we die it goes back from where it came. I'm not religious but I can't really argue with that because it has been proven nowadays by quantum physics that consciousness cannot simply dissolve upon our demise...the way a lot people would like to. Consciousness doesn't relate or report to the empirical laws. If what we see is what it is then we shouldn't be around in the first place. Do you have an apparatus or system in place to see or measure consciousness? Of course not and all scientists are utterly baffled by this particular subject. Most of them prefer not to talk about it because it's something so abstract and indefinable that better don't approach it. Nobody has the right answer. The only progress coming from this corner is done by quantum physics who basically said after long extensive research that consciousness simply cannot die along with the body. It's impossible and no other feasible explanation could be added as why that is. Bottom line we scratch the surface today year 2020 in all fields not just...metaphysics for lack of other name. Drink, eat and laugh because that's your only cut in this life...the wise Solomon was saying. I kind of agree with that.
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You might want to try looking into the philosophy of Gottfried Wilhelm Leibniz, who theorized that everything- trees, rocks, animals, chemicals, etc.- are made up of substances with varying degrees of perceptions and consciousness. See <https://plato.stanford.edu/entries/leibniz/#MonWorPhe> for details.
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I'm developing a setting that has majoritarily experienced a First Industrial Revolution after a period of peace, preceded by a period of warfare sort of equivalent to the Napoleonic wars.
Now I am considering the possibility that a country would have in having developed a strong economy and industry, in parallel of an ongoing armed conflict based around trenches. (Think if World War I would have started earlier than it did, and the technological advancements would have to have been done during the conflict; if that simile helps.)
The causes of the war and the motives for the involved parties to drag out the conflict for so long (i'm thinking as much as 30 years long, but i'm not sure yet, as this seems to be a lot) can be expanded on, but firstly I want to know if it is possible for a country to be involved in this conflict directly and be able to experience industrial and economical growth equivalent to that of the Second Industrial Revolution that happened in Europe before WWI. Note that this country that I'm interested in is not benefitting indirectly from the conflict, nor is it neutral, as it is the one mainly pushing the war forward in time and was the target of the war declaration in question in the first place.
In short, is exponential industrial and economical growth during an extended war time possible at all? If it is, how unrealistic is it to be as strong as the irl 2nd I.R?
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While there have been several good answers about economics, one thing which puzzled me was the desire to have a "hot" war going for decades. Historically, very long periods of warfare, like the 100 years war, the 30 years war, the Seven Years War, the Napoleonic wars and the Cold War were generally short periods of intense combat interspersed with longer periods where the various warring sides were static and building/reorganizing their forces. You could even see the 20th centuries major conflicts (WWI, WWII and the Cold War) as a continuous period of "war" broken into three major episodes of combat and innumerable smaller subsidiary conflicts. The reason these wars went on for so long is the conflict revolved around what was seen as an existential threat to one side or the other (or both).
Reading the war(s) this way also provides a rational for innovations to have time to be created, tested and mature into usable technologies. This also makes it possible to develop the doctrines, strategies and tactics which allow these innovations to be adopted by military forces or civilian economies.
So in order for your scenario to be realistic, the backstory will need to be developed more to identify and highlight the nature of the existential threat, a timeline of the campaigns and probably a political and social timeline as well (for example conversion to wartime economy, the replacement of working men with women or children/retired workers, changes of government due to events on the battlefield [which could advance or retard various projects], alliance partners achieving success or failure requiring your intervention or modifying your timetable and so on).
This will actually be "worldbuilding" om a grand scale.
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I'm going to branch off of what Puppetsock posted and get a bit more theoretical. While he's absolutely correct that economic expansion in the conditions of the first world war is extremely unlikely, you could get more 'alternate history' and make those conditions more agreeable.
The main issue that made WW1 so bloody was that military leadership hadn't really adjusted to the realities of warfare in an industrial environment. The combination of 19th century tactics and 20th century weaponry created massive death tolls, due to the fact that modern artillery and automatic weaponry made attacking an entrenched enemy extremely costly, but political motivations required both sides to keep attempting it anyway.
However, if you postulate political conditions on both sides that allow for less pressure on military leadership for quick victories, then a scenario more compatible with your ideas is possible.
You keep the entrenched defenses that both sides established early in the war, but each side is focused purely on defense, with neither side willing to risk massive losses to press an attack. Instead of having to devote resources to constantly replacing battlefield losses, each side devotes their primary energies to trying to find technological solutions that allow them to break the defenses on the other side conclusively and without risk of mass casualties.
**This requires two fundamental changes from how things actually went down:**
**First:** Defensive weapons technology has to stay ahead of offensive weapons technology. This is particularly critical with regard to long-range artillery and aircraft. You can't have industrial and technological growth driven by military conflict if your cities are being shelled and bombed. Earlier development and wider adoption of radar would serve both purposes very well, for example, making it easier to shoot down enemy aircraft and destroy enemy artillery before they have a chance to do much damage to civilian targets.
**Second:** Both sides have to be able to maintain a wartime economy indefinitely. This means continuous uninterrupted access to all the critical raw materials needed to keep the factories going. Iron, Petroleum, Copper, Rubber, etc. In both WW1 and WW2 the German forces had key resources that they were going to run out of if they didn't win quickly, which drove the need for quick victories at all costs. If both sides are comfortably supplied, than neither will be willing to risk upsetting the status quo unless they have an absolutely insurmountable advantage.
Combining these two factors allows both sides to be potentially able to realize the kind of economic benefits that the United States did during both World Wars. The war provided the political and economic motivation to devote far more resources to industrial and technological development than would otherwise have been possible, yet the United States did not suffer the kind of manpower and infrastructure losses that the rest of Europe did. As long as everything stays in balance, you have a steampunkish equivalent to the Cold War where everybody is preparing for a war that nobody REALLY believes is actually going to happen.
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Not absolutely impossible. But very unlikely.
WWI consumed men at a drastic [rate](https://www.census.gov/history/pdf/reperes112018.pdf), averaging about 50,000 military deaths per week for the whole war, and a similar number of civilian deaths. Those who were not killed were under huge pressure to join up and get involved in the fight. So generally, any potentially productive individuals were siphoned off for the war effort.
Production was also siphoned off for the war effort. This Wikipedia [article](https://en.wikipedia.org/wiki/Economic_history_of_World_War_I) indicates that artillery production grew from 91 in 1914, to 8039 in 1918. Total GDP in the UK grew, but primarily because war production ballooned.
If one side had slackened their effort in order to devote effort to growing their domestic economy, they would have had to accept getting hammered in the war. That could not go on very long before they found themselves over run.
The example of WWI does show one potential way the economy could grow during such a war. And that is the entry of women into industry. Previously, women did not enter factories to any great extent. During the war they entered all sorts of factories in all sorts of capacities, in order to release men for the war. It's possible that this change would have allowed an expansion of the domestic economy adequate to overcome the loss of men to the war. It would require a training period, and quite a lot of adjustment. And the entirety of society would need to be reshaped. But in principle, it could make the difference.
So, if the war caused old outmoded and outdated ideas to be dropped in favor of more efficient ideas, it is just barely possible it could make changes that would cause the economy to be revamped. It would be precarious and slow at first. But just possible.
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Let's think about this:
Facts:
### 1. The cold war was indeed a war of (economic) attrition.
(The west won as it happens - the other blokes got outspent.)
So did either of the two sides have a second industrial revolution during the cold war period?
### 2. Yes, in fact that is *literally exactly what happened*. The "computer and space age" is the only thing ever described as a "second industrial revolution" and that was literally entirely *due* to the cold war, not merely happened at the same time.
In short the answer here seems to be a resounding **"Yes, precisely!"**
Moreover, in general all sides seemed to be spurred on by wars, no matter how much under the gun.
"Fortress Britain" was precisely being attrited to heck, when they invented more or less everything .. radar, "all of computing as we know it" (naturally, being British, they then more or less killed off Mr. Turing as a way of saying "thanks" for doing that), modern jets/aircraft, etc etc etc.
In the US as well as being subject to WW2 on all fronts starting from nothing, the US was able to steal all the relevant nazi scientists and then, astonishingly, invent nuclear weapons all while being in a raging massive world catastrophe.
Really - the answer to the excellent question here is just "Yes, and how."
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When an intensive war is fought, it will put a significant burden on the economies of all the parties involved. That is unless the war is merely used as a stimulus by the parties involved, and not fought with a goal of conquest but with a goal to ensure it's perpetuity.
The novel [Nineteen Eight Four](https://en.wikipedia.org/wiki/Nineteen_Eighty-Four#The_War) discusses a similar theme where there is a perpetual war with the three superpowers who continue to change their alliance, and reframe it as needed.
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Well, yes and no. Nazi-Germany underwent such a "industrialization" and de-industrialization in the late stages of the second world war. All the major factories where destroyed, so the produciton was dispersed into small "smith" shops in towns with the parts assembled by horse waggongs to be assembled in underground tunnels.
Metall was rare and valued, so much so, that shot down bombers where quite the prized objects. Significant parts of the produced technology was wooden-frame.
The horten-planes - wooden frame. Waterfall rockets? Wooden frame, with a metall sheet exterior.
The fuel? Mostly made from coke. Rubber? Sythesized from coke.
So, to sum it all up, its possible to have a industrialization that is completely different and based upon different materials, but its not very economical and if you start to use solar to harvest nitrogen for explosives, you start to actively devour the populations food sources. (Which the nazis did- they setup there own population for a mass-starvation in the last year of the war).
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*Far, far away from the Earth, there is a nebula. An enormous cloud made of 78% nitrogen, 20% oxygen and 2% other non-lethal materials. These gases swirl around a star, and the pressure around it is more or less 105 pascals. This star has several planets around it. In some of those planes, life sprouts. In a few, intelligent civilizations rise. They, each in their own way, develop flying machines. With these wonderful ship-like machines they can travel between worlds (no need to wear a helmet). The interplanetary sailors even tell tales about monstrous whales flying through the system.*
In this world that only exist on my imagination, and now in yours, how many of those things are actually possible?
My main concern in this world is:
**Could a star exist with this cloud similar to earth atmosphere around it where a person could breathe without much effort?**
Near a planet the atmosphere could be thicker meanwhile in the interplanetary space could be a thinner atmosphere like in a high mountain. This cloud can be as big as you want, but the minimum size should be at least one AU. Because a star and a planet like Earth orbiting it should fit inside the cloud.
**BONUS I:** Assuming this system is possible; could a ship (like a zeppelin) navigate through worlds? The technology of those civilizations is between century XVIII and XIX.
**BONUS II:** Could it be possible for those worlds to have something like a continuous electromagnetic-pulse preventing them from develop electronic devices and forcing them to be in an eternal middle ages state? It may come from the star, or radiation from the nebula itself.
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> Could a star exist with this cloud similar to earth atmosphere around it where a person could breathe without much effort?
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Nope. The solar wind and radiation pressure and a combination of planetary and stellar gravity would either blow away or hoover up all the gas cloud in relatively short order. That's why there's a fairly hard vacuum between planets in our own solar system, after all.
You have two possibilities, I think. One, handwave physics away and create a fantastical world... Adam Roberts did this in *Polystom*. This isn't a bad solution, and does make a lot of other things in your setting straightfoward.
Alternatively, constrain the gas cloud somewhat, remove the requirement for it to fill all the space around the star and every planet and have a way for it to be replenished. Larry Niven did this in *[The Integral Trees](https://en.wikipedia.org/wiki/The_Integral_Trees)*, with a free-fall breathable gas torus in space around a neutron star, continually replenished by the destruction of an associated gas giant. You can't trivially fly through air from a planet to the gas ring, but the setting is a teeny tiny bit more physically plausible. Slightly. You wouldn't be able to seamlessly fly from a planet into the gas cloud, though.
*Edit*: there is a third option, which is to have a massive freefall habitat with artificial stars and maybe worlds in it. This is the approach Karl Schroeder took with his *[Virga](https://www.kschroeder.com/my-books/sun-of-suns/engineering-virga)* setting, with a 5000 mile diameter sphere of air orbitting Vega. Again, you can't fly from a real planet into such a habitat without travelling through vacuum first, but it overcomes more of the physics issues that the exposed-to-space gas torus has.
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> Assuming this system is possible; could a ship (like a zeppelin) navigate through worlds? The technology of those civilizations is between century XVIII and XIX.
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Flight through air in freefall or microgravity has some additional challenges not found in a gravity well (lift becomes an inconvenience instead of a necessity, and torque from propellers becomes more problematic, to name but two things), but there's no reason it shouldn't be possible.
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> Could it be possible for those worlds to have something like a continuous electromagnetic-pulse preventing them from develop electronic devices and forcing them to be in an eternal middle ages state? It may come from the star, or radiation from the nebula itself.
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This is an entirely separate question, so I'm not going to answer it here. If you're interested in an anwer, ask it separately.
You should also ask yourself, however, is this really necessary? With the ability to trivially fly up into "space" and build whatever vast floating structures you want, or visit other worlds (are there asteroids in your gas cloud?) and mine or farm them as you see fit, there's plenty of scope for a sprawling low-tech civilisation to last for quite a long time.
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# No to the star, Yes to the travel
A star cannot exist in that type of atmosphere for *many* reasons. Not the least of which is *heat*. Temperatures range into the [millions of degrees](https://www.space.com/17137-how-hot-is-the-sun.html), which destroys any chance of a stable atmosphere. Furthermore, any particles in the air would result in continual [dust explosions](https://en.wikipedia.org/wiki/Dust_explosion).
This of course does not mention issues with gravity (air does not "sit" in an ethereal plane; the gravitational force of the star and planets would pull the atmosphere toward themselves), nor drag, nor electromagnetism, nor radiation, nor any number of other issues.
That being said, if we hand-wave over these issues and instead simply accept the premise where we have a "space" which is more like an atmosphere between planets, then yes, I suppose a ship could "sail" between planets in one of many different mechanisms. When you have a "space" which is more atmosphere than space, then you have enough particles to breathe, push against, create lift, etc.
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Standard stars forms from the collapse of hydrogen nebulas. The nebula self-gravity concentrates matter in the center. Friction eventually generate enough pressure to start a nuclear fusion process and the star ignites.
What if we have a nebula made with air? Let's assume that it is spheric and have 1 astronomic unit radius (i.e. $1.5 \times 10^{11}\,\text{m}$) and that each cubic meter of air weights $1.2\,\text{kg}$.
This means that all that air weights this:
$$ 1.2\,\frac{\text{kg}}{\text{m}^3} \times \frac{4}{3} \pi (1.5 \times 10^{11} \,\text{m})^3 = 1.6964 \times 10^{34}\,\text{kg}$$
The Sun mass is:
$$\text{M}\_\odot = 1.989 × 10^{30}\,\text{kg}$$
So, converting all the air mass in solar masses we have:
$$ 1.6964 \times10^{34}\,\text{kg} \times \frac{\text{M}\_\odot}{1.989 × 10^{30}\,\text{kg}} = 8528\,\text{M}\_\odot $$
With all that 8528 solar masses compressed in a volume of 1 AU radius, the result is pretty much obvious now:
$$\text{BLACK HOLE}$$
So, sorry. What you want simply is not possible.
Quoting from [this article](https://arxiv.org/pdf/1010.5550.pdf):
>
> [...] if the CCSN [core-collapse supernova] mechanism lacks efficacy and fails to revive the shock and continued accretion pushes the PNS [protoneutron star] over its maximum mass. In this last channel to a stellar-mass BH, there is no electromagnetic (EM) signal other than the disappearance of the original star.
>
>
>
It is way beyond the maximum mass, so it will collapse directly to form a black hole.
] |
[Question]
[
**This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information.
Many science fiction stories, movies, and shows involve characters undergoing explosive decompression, the technical term for a rapid drop in pressure, usually all the way to a vacuum. Frequently, this is used as capital punishment, since shoving someone out the airlock without a suit is an efficient way of killing them in space. However, most of these depictions of explosive decompression, as well as most sources I have been able to find on the subject, disagree wildly on the specifics. Some involve the skin freezing and/or frosting over (probably wildly inaccurate, as a vacuum is actually the best possible thermal insulator), some describe blood boiling and eyeballs exploding, and some show no outward changes as the victim appears to suffocate.
The question is, **what would actually happen to a person suddenly launched into space?** Additionally, would the results change significantly if the victim is in sunlight, as opposed to shadow?
[Answer]
We actually have first-person testimony about what happens under these circumstances. In 1966 Jim LeBlanc was testing a space suit in a vacuum chamber when his supply line came detached and let his atmosphere out very quickly. This clip:
<https://www.youtube.com/watch?v=KO8L9tKR4CY&feature=youtu.be>
Includes some original footage as well as interviews with people involved. Jim lost consciousness very quickly - measured in seconds. The last thing he remembers was feeling the saliva on his tongue boiling. They were able to quickly re-pressurize the chamber and he regained consciousness shortly, without any permanent damage.
Passing out quickly is likely an unavoidable consequence. This is very similar to what happens with [inert gas asphyxiation](https://en.wikipedia.org/wiki/Inert_gas_asphyxiation). In short, the extremely low pressures cause the lungs to lose oxygen with each "breath". As a result (in the case of inert gas asphyxiation) it is possible to pass out in even just a few breaths. In a vacuum of course "breathing" doesn't really make sense, but your lungs would still effectively leak oxygen out of your body, causing you to pass out rapidly (as happened to Jim in a vacuum chamber).
Given this, you might consider holding your breath to stop yourself from rapidly passing out. I'm not confident enough to say for sure what will happen if you do, but all signs suggest that it will be a bad choice even if it is possible (which it probably isn't). When scuba diving, holding your breath while surfacing is a very dangerous move and is virtually guaranteed to cause [pulmonary barotrauma](https://www.thoughtco.com/pulmonary-barotrauma-and-scuba-diving-2963056). A severe pulmonary barotrauma can cause injuries that lead to rapid fatality such as [arterial gas embolism](https://en.wikipedia.org/wiki/Arterial_gas_embolism) or [tension pneumothorax](https://en.wikipedia.org/wiki/Pneumothorax#Tension_pneumothorax). The risk of pulmonary barotrauma is related to the rate of relative change of air pressure, and for scuba diving is [therefore most dangerous at the surface](https://www.thoughtco.com/depth-and-pressure-scuba-diving-2963200), when moving from, say, 2ATM of pressure to 1ATM. As a result I expect that going from 1ATM to 0ATM is equally, if not more, dangerous to someone trying to hold their breath.
It took about a minute and a half to re-pressurize Jim's chamber. He ended up with an earache, but otherwise no visible injuries. However, longer exposure could certainly have done more damage to his body. Unfortunately, I'm not sure what the longer term damage is myself, nor do I have any great references (pretty sure that study hasn't been done). Most of the immediate effects (such as Jim feeling his saliva boil) are caused by the lack of pressure. Technically his saliva was both boiling and freezing at the same time, which is what water does in a vacuum due to lack of pressure:
<https://www.youtube.com/watch?v=2IOyJa8NSk0>
The lack of pressure is the most dominant effect, although I'm not sure how quickly the body would actually freeze. Sunshine or shade won't matter immediately. He will freeze over regardless (due to lack of pressure), so the only effect of sunshine or shade will be to control the rate at which his ice escapes via sublimation. Warmer areas of space = faster sublimation and therefore quicker time to go from popsicle (aka frozen body) to mummy (aka dried body). For long-term results, I refer you to the relevant xkcd.
<https://what-if.xkcd.com/134/>
[Answer]
What happens to the *person* is simple. What happens to their body involves a few more steps.
The first thing that happens is you scream. Well, you act to scream or the scream acts on you. The lungs are designed to withstand about 1/10th of an atmosphere of pressure, which is the typical delta occurring during breathing. You either scream all your air out of your lungs, or that air forces its way out, doing substantial damage along the way. This effect is probably not all that important for someone being executed by vacuum. For those who want to live, it matters greatly. Divers engaging in what is called a Controlled Emergency Swimming Ascent (CESA) learn to exhale while they are ascending to give the air in their lungs a way out. This *decidedly* unintuitive maneuver is essential for your survival.
The next thing happens is that you [lose consciousness](https://www.scientificamerican.com/article/survival-in-space-unprotected-possible/) at around 15 seconds. The lungs are a powerful gas exchange mechanism, and you just exposed them to pure vacuum. The vacuum rips the oxygen right off of the hemoglobin, and then delivers that blood to the brain. 15 seconds later it reaches the brain, and you lose consciousness almost immediately after that. Death arrives soon after, as if the heart stopped beating (it may be beating, but it's not delivering oxygenated blood, so it's not helping at all).
You can survive like this for a while:
>
> ... one 1965 study by researchers at the Brooks Air Force Base in Texas showed that dogs exposed to near vacuum—one three-hundred-eightieth of atmospheric pressure at sea level—for up to 90 seconds always survived.
>
>
>
After that, the answer is a bit more boring. You do have issues with water boiling, but its not instantanious. Space is actually a very poor conductor, so it doesn't conduct any heat away. Your body radiates at a very low rate. Almost all of the cooling comes from evaporation, which is a very localized effect. Astronauts involved in accidents like this remember feeling the evaporation off of their tongue before losing conciousness. However, this takes a long time. At least as long as it takes to freeze in a cold weather environment. The cool needs time to work its way in (or, phrased the other way, the heat needs time to work its way out). Your eyes, however, do not typically "explode:"
>
> Water in the soft tissues of your body vaporizes, causing gross swelling, though the tight seal of your skin would prevent you from actually bursting apart. Your eyes, likewise, would refrain from exploding, but continued escape of gas and water vapor leads to rapid cooling of the mouth and airways.
>
>
>
In fact, one of the new space suit designs, the [Biosuit](https://www.space.com/27210-biosuit-skintight-spacesuit-concept-images.html) actually takes advantage of this. Human skin can actually hold its own against a vacuum on small scales. Obviously, large areas of skin suffer from expansion due to fluids entering the area, but if you compress the skin at a gross level, the microscopic structure can take the vacuum. The biosuit is actually not vacuum tight. The air can escape through the weave of the suit. The result? Your body can actually cool itself via presperation just like it does in the hot desert sun! Your body emits sweat like it usually does, and that sweat evaporates into the vacuum, cooling you off!
Not that that makes me any less disturbed at the idea of exposing my skin to the vacuum of space, but it has been done. One of the more famous leaks on the ISS was resolved by [covering it up with a thumb](http://www.astronomy.com/news/2018/08/international-space-station-losing-air-through-a-tiny-hole-astronauts-safe). (the hole was obviously later fixed more permanently, first by Kapton tape, and later I believe it was cemented shut)
Once the effects of evaporation stop mattering and you become inert, what happens to the body is *exactly* what happens to an asteroid of similar size. If its in an environment that gets hot due to the sun, it gets hot. If it's in an environment that gets cold, it gets cold. This happens on a long timescale, at least compared to the 15 seconds of meaningful screaming.
[Answer]
A. **Man puts Arm In A Vacuum Chamber**
This video shows what happens and, towards the end, shows facts and figures from **NASA's Bioastronautics Data Book 2nd Edition** - <https://youtu.be/iWGGMchu6mQ?t=67>
[](https://i.stack.imgur.com/D417N.png)
---
B. **The Crew That Never Came Home: The Misfortunes of Soyuz 11**
>
> The mission ended in disaster when the crew capsule **depressurized**
> during preparations for reentry, killing the three-man crew. <https://en.wikipedia.org/wiki/Soyuz_11>
>
>
>
“They knocked on the side, but there was no response from within. On opening the hatch, they found all three men in their couches, motionless, with **dark-blue patches on their faces and trails of blood from their noses and ears**. They removed them from the descent module." <http://www.spacesafetymagazine.com/space-disasters/soyuz-11/crew-home-misfortunes-soyuz-11/>
---
] |
[Question]
[
I'm making a world where I want domesticated Mimics to be a thing.
These Mimics are pretty similar to the original concept of D&D Mimics: shapeshifters that imitate objects, and hunt by imitating something desirable to their prey, then attacking when the prey comes close using a sticky secretion and a bludgeoning pseudopod.
The questions I have are as follows:
1. ***Why* would a creature with this kind of lifestyle be trainable, let alone domesticatable?**
2. **How might one go about domesticating and training them?**
Animals that humans have domesticated tend to have similar characteristics: social, active, and preferably herbivorous (with a few exceptions). Mimics are none of these.
I want them to be roughly similar to dogs in intelligence: not civilized creatures, but smart enough to learn and sociable enough to train for various diverse purposes (the most obvious being as house guards, but can also make good pets, can be used by hunters as decoys, and can even help the disabled using the versatility a tentacled shapeshifter has to offer). As with dogs, they come in various different breeds that vary in size and disposition.
The exact details of their evolutionary progress aren't important (they can be presumed to have evolved from an already existing class of amorphous muscular blobs) but they are a natural creature that evolved in a natural environment, without magic or human involvement ("wild" Mimics usually imitate plants or dead animals to lure their prey). As such, their intelligence and disposition should *make sense* for a creature with their lifestyle to have.
(Interestingly, D&D *does* have a precedent for the occasional friendly Mimic and even talking Mimics, though these are rarely used. But this is more for gameplay reasons and isn't really explained in a plausible manner.)
**The main goal is to design a creature that, while functionally a traditional shapeshifting Mimic, also has a plausible survival-based reason for having a "domestication-friendly" brain despite its solitary, ambush-predator hunting strategy.**
---
*Additional details about these Mimics:*
Mimics are obligate carnivores. Like snakes and crocodiles, they prefer large single meals over regular small ones, at least in the wild.
While they can change their topography, color, and texture, and are capable of "locking" their muscles into place to remain stationary for long periods of time without expending excess energy, they are basically muscular blobs and can't really maintain a convincing shape while in motion (though they are capable of "jiggling" a part of their body to attract prey, and can form basic shapes like tentacles). They also can't change their mass, though some cleverer ones can change their apparent volume by expanding hollow spaces inside their bodies.
They are not good at moving quickly (the fastest they run is about the speed of a brisk human walk, and they don't like to do this often) but they can lash out with a pseudopod extremely fast, and they can climb walls using a combination of shapeshifting and their sticky glue. House Mimics can be trained not to "slime" but this is difficult.
Wild Mimics rarely prey on humans (not enough opportunity for the risk, and not enough overlap between the items humans go for and those that more common prey go for). Most "chest Mimics" are *domesticated* Mimics who have been specifically trained to guard a house by imitating an object that a thief is likely to go for. Some notorious Mimics *have* been known to target humans though; as with other "man-eating" animals they are usually hunted down and killed.
They can see using any part of their body, but their "eyes" must be dark and smooth for them to see effectively. This makes it difficult for them to disguise themselves perfectly and see at the same time.
Mimics are not born knowing how to shapeshift, nor can they imitate an object perfectly on sight: they learn through experience and observation (usually by extending an "eye" on a pseudopod to look at themselves). The more a Mimic has practiced a particular form, the quicker it is able to take that shape and the more accurate the imitation will be. Young Mimics can take a few hours taking on a new form; more experienced ones can adopt a shape in seconds.
Mimics *can* pass the mirror test, and learn much faster when they have a mirror available.
[Answer]
### Like cats, wild Mimics teach their children to hunt
Imitating one's general surroundings for purposes of camouflage is one thing, intentionally transforming into *bait* is much trickier, as it requires the Mimic to know what its prey will be attracted to. Randomly transforming into different objects and waiting until a prey animal happens to investigate is a very, very slow method of learning, and probably not a viable survival strategy (while some animals *are* naturally curious and will investigate anything unusual, animals living alongside Mimics will probably lose this behavior pretty quickly). Mimics' viability as a species improves substantially if their parent gives them a "head start" by teaching them which types of objects are useful to transform into.
Baby Mimics will instinctively transform into objects they find in their environment, and the parent or parents encourage transforming into *useful* forms by collecting such objects and surrounding their children with them, giving their children a head-start on hunting. A parent Mimic will also teach by transforming in front of their child, and the child will naturally mimic (ha) its parent. Adult Mimics can also learn by observing *other* Mimics, especially when arriving at a new location which might have different prey. (They can presumably identify other Mimics through smell.)
A lot of domestic animal behavior is derived from a modified parent-child relationship, with the human taking the role of the parent (the domestication process often extends an animal's *neotenous* qualities, making it retain "child-like" behavior throughout its life). In addition to making the Mimic more sociable, this allows the owner to encourage the Mimic to adopt certain forms; since wild Mimics naturally imitate objects their parent presents them, a Mimic will naturally transform into objects that their owner presents to them.
### A theory of mind?
Mimics also become much more viable as a species if they are able to learn new useful forms by observing prey and watching which objects their prey tend to be attracted to. This kind of adaptive behavior is one of the hallmarks of higher-level intelligence and suggests that Mimics are significantly smarter than your typical ambush predator to begin with.
[Answer]
It is absolutely possible and has been done.
**Stage 1 - Selective breeding**
Domestic dogs are known to have descended from wolves. The exact how and why can only be guessed at. However we know from a famous experiment with Siberian foxes that domesticated behaviour can be selected for.
>
> In the 1950s a Soviet geneticist began an experiment in guided
> evolution. He wanted to show how domestication works
> <http://www.bbc.co.uk/earth/story/20160912-a-soviet-scientist-created-the-only-tame-foxes-in-the-world>
>
>
>
The method is very simple. Reject or kill the most human-aggressive animals and breed from the least aggressive and most compliant.
In the case of the domestic dog we know that this process wasn't so straightforward. Dogs were bred to hunt, to run, to guard and so on. Thus many breeds will still be aggressive unless trained not to be.
Results can start to be seen quite quickly over just a few generations.
**Stage 2 - Training**
Almost any (if not every) intelligent animal can be trained by *operant conditioning*
>
> Operant conditioning is a method of learning that occurs through
> rewards and punishments for behavior. Through operant conditioning, an
> individual makes an association between a particular behavior and a
> consequence (Skinner, 1938).
>
>
>
These days punishment is considered unnecessary most of the time and nearly everything can be achieved with rewards. Note that punishment does not necessarily mean violence - it could mean withholding a treat for example. With many dogs, a stern 'No!' will be sufficient punishment to stop an undesired behaviour.
---
There are big problems with training a wild carnivore (and some herbivores) without having bred for domestication. We regularly hear about trainers of big cats and of bears being seriously injured or killed. This is because no amount of training will on its own overcome natural instincts. Wild carnivores often fight and injure each other.
If you search for 'bear kills trainer' then you'll find plenty of examples.
[Answer]
There's one detail that was left out of the mimic description. It's the same important detail that was left out of the velociraptor details for dramatic purposes in the Jurassic Park films.
They're only up to 10kg and about knee high.
We have successfully domesticate two predators, others can be tamed and trained, but only two are fully domesticated. The cat and the dog. Dogs are pack hunters, it's comparably easy to replace a pack member with a human. Cats are lone ambush predators, there's a theory that they domesticated themselves by virtue of lack of fear of humans allowing them to hunt the vermin attracted by our food stores and waste.
The mimics in your world replaced the domestic cats. They learned to hunt among our waste, slowly losing their fear of humans while we appreciated their removal of the scavengers attracted by our presence.
[Answer]
One method comes to mind immediately:
**Mimic Treats** --- your mimics are of canine intelligence, sociability and are able to learn. I'd suggest finding out what it is mimics like best to eat (probably small to midsized rodents (squirrels, rabbits, field mice) and scavengers. Just make up a couple packets of rabbitsnax and whenever your mimic tries to mimic whatever it is you'd like him to mimic, you pop a rabbitsnax down his gullet!
Eventually, you might also train him to eat more delicately from your hand. Without actually sliming you and trying to eat you actual hand!
[Answer]
I think the answer to any iteration of the question is **"feed it".**
Animals hunt to eat. There aren't too many animals that would continue to hunt (or at least to migrate) if a steady food supply presented itself.
Trapping and moving an animal certainly would place it in panic mode, and make any attempt to tame more difficult, but give it a big meal, and they usually calm down, at least for a bit.
Assuming a mimic doesn't need to "keep moving" like a shark, or need a large roaming/hunting area, a steady diet should calm it down pretty quickly. Having no information on family groups, it might be safe to assume they're solitary creatures, and not having any other mimics in the area might not be a problem.
] |
[Question]
[
If I push a couple of magnetic asteroids into mars gravitational field, could they form an interlocking series of magnetic fields able to protect mars from solar winds?
Size limits for asteroids is any that can become satellites or moons without majorly altering mars regular orbit, or so small that they would cause mars to have Kessler syndrome.
Bonus: If impossible for asteroids could I do it with electromagnets sent from a planet's surface or built into asteroids?
[Answer]
**No**
The issue isn't strength, it's size. Earth's magnetic field is remarkably weak. On the surface, Earth's magnetic field is only 0.25-0.65 gauss. Your average household 'fridge magnet is 100 gauss, up to 400X the strength of Earth's magnetosphere.
But Earth's magnetosphere is MASSIVE.
And that's your problem. Mars is a tenth the mass of Earth, but doesn't have a strong enough (per the needs of your question) magnetic field. An asteroid could be very strong, but without all that lovely mass (in the form of a liquid metal core), its field will be very, very small.
Long story short, by the time you have enough magnetic asteroids to produce a sufficient addition to Mars' magnetosphere, they'd be several times (perhaps many times) the mass of the planet. It would all collapse into a new planet.
The same problem applies to manufactured magnets. Strong, but small. Large fields require massive field-generators. You know, planet-sized.
So, no.
[Answer]
**Maybe.**
You would use 1 magnetic shield, at the L1 Lagrange point. Lagrange points are places where an item can be placed and stably stay as relative to a planet and its star. There are 5. L1 is between the planet and star.
[](https://i.stack.imgur.com/9zTDH.jpg)
<https://www.space.com/30302-lagrange-points.html>
I was wondering if you could put a magnetic asteroid (or better: a solar powered electromagnet) at L1 and shield Mars that way. NASA has beat me to the idea which is good, as it is pretty wild and I am sure would get thrashed thoroughly here if proposed first here by me. But NASA!
>
> In answer to this challenge, Dr. Jim Green – the Director of NASA's
> Planetary Science Division – and a panel of researchers presented an
> ambitious idea. In essence, they suggested that by positioning a
> magnetic dipole shield at the Mars L1 Lagrange Point, an artificial
> magnetosphere could be formed that would encompass the entire planet,
> thus shielding it from solar wind and radiation.
> <https://phys.org/news/2017-03-nasa-magnetic-shield-mars-atmosphere.html>
>
>
>
So there you go. I suspect that a sprawling solar electromagnetic umbrella might be stronger and bigger than an ferromagnetic asteroid. But maybe a magnetic asteroid would suffice if that is what you had handy.
[](https://i.stack.imgur.com/Hfpad.jpg)
[Answer]
In my answer to this question:
[How can I keep an atmosphere on Mars?](https://worldbuilding.stackexchange.com/questions/123739/how-can-i-keep-an-atmosphere-on-mars)[1](https://worldbuilding.stackexchange.com/questions/123739/how-can-i-keep-an-atmosphere-on-mars)
I suggest another possible way to protect the natural or terraformed Martian atmosphere.
It is a rather bold idea, but no more so than terraforming Mars.
] |
[Question]
[
A concept I've encountered a few times is aliens with "vastly" different biology than terrestrial creatures. In this case, I'm interested in replacing the parts that use oxygen with something a bit milder (a worse oxidizer).
I'm looking for something that would, biologically, serve the same function as oxygen in a human. It should be a gas in a reasonable temperature range around liquid water, and it should be reasonably produced in sufficient quantity by natural processes although I'm not concerned with the actual manner in how it is produced.
Bonus points if it's something that sticks around better in lighter gravity.
[Answer]
**Disclaimer:** I love this question, but I don't have the PhD to answer it well. I'm going to take a shot at it nonetheless. I won't laugh at me if you won't laugh at me, OK?
We're looking for a way to replace [CHON](https://en.wikipedia.org/wiki/CHON), an acronym for Carbon, Hydrogen, Oxygen, and Nitrogen, the four most common elements in Terrestrial life. Our goal? To create a biome that isn't based on Oxygen (I need to ignore "mild" aka "worse at oxidizing" 'cause, frankly, I'm not even sure if I can make this ~~believable~~ work).
Basically, you need a liquid to replace water that isn't based on oxygen. For no reason other than the feel of sunlight on my left cheek, I'm going to try Fluorine.
As a test, H2F ([fluoronium](https://en.wikipedia.org/wiki/Fluoronium)) is an acid. From a ridiculous POV, so is water (the "universal solvent"). Humans don't dissolve when they drink water, so let's assume a creature that won't dissolve when drinking fluoronium.
So, let's take on glucose. All creatures need energy, right? Can I make a glucosy something using fluroine? I'm guessing the basic problem is the CH2OH part of the molecule. What is X for XH2FH? I'm thinking phosphorous. PH2FH.
*And I'm not going to take on proteins 'cause if by now you think I'm doing anything other than pulling interesting associations out of an etherial hat... I'm so far out of my depth... But I'm having fun, so ppfffffhpt!*
So, now we have PHFN. My spidey-sense is telling me we can't use Nitrogen with Fluorine, so we need something a bit more adept: let's use chlorine! (It actually works well with Fluorine. I think...) That gives us PHFCl and, I'm guessing and hoping... the building blocks of life...
On a planet not dissimilar to Venus. Hot and acid prone. The creature would be much heavier than humans (heavier molecules), and would likely favor yellow over red for the basic wine of life. (You know... blood...)
So, fluorine...
* It is an organic oxidizer
* It is gaseous at room temperature
* It exists on my planet vs. oxygen in the same ratio that oxygen is to fluroine on Earth.
* The molecules it creates would be heavier, which is good for lighter gravity.
And though students of chemistry and the very Angels in Heaven are probably weeping over this answer (or laughing, it might be hard to tell the difference with all the tears), I give you my favored candidate:
***Fluorine***
[Answer]
Fluorine and Chlorine are the only common gaseous oxidizers that don't contain Oxygen, to the best of my knowledge. However, neither are especially common in the universe. Furthermore, because they've got 7 electrons in their outer shells, they don't tend to form terribly complex compounds. Oxygen is common, forms lots of different compounds, and is a good oxidizer.
A more probable oxidizer would be Sulfur. [Sulfur reducing bacteria](https://en.wikipedia.org/wiki/Sulfur-reducing_bacteria) can use it in place of Oxygen, so it's use is definitely biologically possible. However it won't be a gas, or even a liquid, in environments with liquid water. Sulfuric acid would be liquid, and makes a great oxidizer, but it contains oxygen, so any environment with sulfuric acid will probably contain oxygen, as well.
[Answer]
The element whose properties are closest to oxygen is right below it in the periodic table: sulfur.
Wikipedia has this to say about its biological role:
>
> Sulfur oxidizers can use as energy sources reduced sulfur compounds, including hydrogen sulfide, elemental sulfur, sulfite, thiosulfate, and various polythionates (e.g., tetrathionate). They depend on enzymes such as sulfur oxygenase and sulfite oxidase to oxidize sulfur to sulfate. Some lithotrophs can even use the energy contained in sulfur compounds to produce sugars, a process known as chemosynthesis. Some bacteria and archaea use hydrogen sulfide in place of water as the electron donor in chemosynthesis, a process similar to photosynthesis that produces sugars and utilizes oxygen as the electron acceptor.
>
>
>
If oxygen were not present in a world, sulfur would be the next candidate for an oxidizer.
Elemental sulfur is usually solid, but it easily forms gases such as H2S. This is a gas, slightly heavier than O2, and with the characteristic smell of rotten eggs. So any planet with plenty of hydrogen and sulfur (which is not hard... it is one of the most common elements) should have gaseous sulfides.
[It also has a cool theme song](https://m.youtube.com/watch?v=PAAvNmoqDq0).
[Answer]
I am shocked an amazed that *nobody* already mentioned [anaerobic respiration](https://en.wikipedia.org/wiki/Anaerobic_respiration)--the actual usage of oxidizers-that-are-worse-than-oxygen by actual real organisms on Earth!
Fluorine is not a weaker oxidizer than oxygen, so that's out.
Chlorine is, and the remaining halogens but it's hard to imagine a situation where there would be enough free chlorine in the environment to replace oxygen (although you could, in some types of environments, use chlorine as a secondary option, along with some other oxidizer). There are, however bacteria that use halogenated organic compounds as oxidizers, producing halide ions / acids and hydrogenated organics as output products. So, you could have aliens breathe simple halogenated organics like methyl chloride ($CH\_3Cl$), producing CO2, methane and hydrochloric acid instead of CO2 and water as respiration products.
Other electron receptors that are actually used by Earthling organisms include:
1. Fe(III) ions; e.g., ferric oxide ($Fe\_2O\_3$) or magnetite (iron (II,III) oxide, $Fe\_3O\_4$) which gets reduced to Fe(II) ions (e.g., $FeO$) and water. Manganese, cobalt, and uranium compounds can also serve as oxidizers, but all of them are rather difficult to breathe, so, moving on...
2. Nitrate, nitrite, or free nitrogen oxide gasses. These are produced in large quantities by nitrogen-fixing organisms because they are actually needed in terrestrial biochemistry, and when the organisms containing them die, they can be reclaimed by decomposers as oxidizers. Hal Clement's *Nitrogen Fix* posits a world in which nitrogen-fixing organisms go into overdrive and eliminate all free oxygen from the atmosphere--which is reasonable, because reacting nitrogen with oxygen is itself slightly exothermic, and could be used as a defense mechanism by plant-analogues to avoid oxygen poisoning (whereas, on our world, oxygenic photosynthesizers just went ahead and poisoned everything...). Using nitrate as an oxidizer produces about half as much energy as straight oxygen, with diatomic nitrogen and water as wastes.
3. Fumaric acid (C4H4O4), and various other organic oxidizers. Fumarate oxidation produces succinic acid (C4H6O4) as a byproduct. Theoretically, this can be further reduced down to methane and CO2, or all the way to methane and water. In an alien biosphere, simpler organic molecules, like acetylene, might be used as weak oxidizers, producing methane as a byproduct.
4. Sulfate, sulfite, free sulfur dioxide or sulfur trioxide gas, or elemental sulfur. These all produce hydrogen sulfide and (with the exception of elemental sulfur) water as byproducts. Sulfur trioxide would be expected as a gaseous oxidizer on sulfuric acid worlds (like a cooler, smaller Venus), in which case it would likely only be reduced to sulfuric acid, rather than all the way to water and hydrogen sulfide.
5. Carbon dioxide. This only works if you can figure out a *really* strong source of reducing potential to work into your food source; on Earth, it only gets used in the presence of excess hydrogen gas. The ultimate waste products are methane and water (possibly with a detour through acetic acid).
And all of the gaseous options (various nitrogen oxides, sulfur dioxide, sulfur trioxide above 45C, simple desaturated or halogenated organics, and carbon dioxide) all stick around better in lower gravity than oxygen does.
[Answer]
The strongest [allotropic](https://en.wikipedia.org/wiki/Allotropy) oxidizers (that are somewhat stable in our atmosphere) are, in order of decreasing effect, Ozone (O${\_3}$), Oxygen(O${\_2}$), Florine(F${\_2}$), Chlorine(Cl${\_2}$) and Bromine(Br${\_2}$), of these the first four, O${\_3}$, O${\_2}$, F${\_2}$, and Cl${\_2}$ are all very much gases around 0°C and F${\_2}$ and Cl${\_2}$ are both heavier than O${\_2}$ meaning that they're more compatible with a world with lower surface gravity. Br${\_2}$ is a liquid at standard temperature and pressure only becoming a gas around 60°C at sea-level. Depending on the prevailing conditions on the world you wish to create any of the three [halogens](https://en.wikipedia.org/wiki/Halogen) is a potential candidate as a non-oxygen oxidiser for biological systems. Broadly speaking any oxidiser that can replace oxygen in a mirror [respiration](https://en.wikipedia.org/wiki/Cellular_respiration) pathway can also reasonably replace oxygen in a mirror [photosynthesis](https://en.wikipedia.org/wiki/Photosynthesis) pathway but unfortunately I'm not a biochemist so I can't even take a stab at what those pathways would look like.
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[Question]
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There exists a bow capable of sending a **1000 gram arrow** flying at about **1900 mph**. The bow is a re-curve resembling the old Mongolian style bows and is made of steel.
**What sort of modifications would have to be done to an arrow to keep it stable at this speed?**
This includes materials, fin length and size, as well as rigidity. Keep in mind that this speed doesn't have to be maintained. This is simply the highest reached velocity.
Also it is important to just handwave any harm to the user. The bow is about 1.5 times bigger than an average Mongolian bow and its parts also are 1.5 times bigger than their equivalents.
[Answer]
There are "arrows" which travel at supersonic speeds, but they are not fired by bows, but by large calibre tank cannons. They are technically knowns as APDSFS rounds (Armour Piercing Discarding Sabot Fin Stabilized)
[](https://i.stack.imgur.com/2ULW2.jpg)
*M829A3 round*
The "petals" of the sabot serve to keep the round centred in the barrel during firing, and also fill the barrel so the propellant gasses don't flow past the round, providing the greatest energy transfer to the projectile. Once it clear the barrel, the sabot pets peel away, leaving the "dart" to carry on to the target. Soviet and Russian APDSFS rounds have similar properties, but use a different form of sabot:
[](https://i.stack.imgur.com/1G2mj.jpg)
*Russian Bm15 round for a 125mm tank cannon*
The specific shape of the APDSFS penetrator is related to factors such as cross sectional density, the need to maintain velocity downrange and the ability to penetrate armour, especially composite armours and various forms of spaced armours. The long, thin "dart" shape provides low drag (preventing the velocity from dropping too much with range), and concentrates the energy in a very tiny area on impact, improving the ability to penetrate armour. Extra fun can be had from using high density depleted uranium, as the material becomes "pyrophoric", spontaneously igniting in the presence of oxygen once it passes through the armour (the frictional heat provides the energy for ignition).
Now you have not mentioned what, exactly a supersonic arrow is needed for, but it would have several of the properties of an APDSFS penetrator. The dart shape for low drag and armour penetration is a must. If you are actually using a bowstring and improbably large bow to provide the launching energy, a stiff metal dart will have less tendency to flex like a wooden arrow or quarrel, allowing for greater energy transfer to the projectile.
[](https://i.stack.imgur.com/UZUa0.jpg)
*Flexing of an arrow when launched*
[Answer]
Let's have a look at the total energy required. There is the formula: E = 1/2 mv^2, and in this case you get:
```
E = 1/2 * 1(kg) * 849 (m/s) ^ 2
E = 360 kj
```
That is more energy than is present in a ... .50 cal rifle (20kj) by more than an order of magnitude. So to say you're going to have issues is an understatement.
The major issue you are going to have with the arrow is splintering. You are accelerating your arrow crazily fast. It goes from 0mph to 1900mph in less than one meter of space. For the mechanics of a bow/arrow, this means all that force is concentrated on the back of the arrow where the string pushes against it. Without the support of a barrel, you'd be hard pressed to stop the back of your arrow "mushrooming" out. It could be done, but you'd likely need some hard material at the back of your arrow.
I'd just go for something more like a long bullet than an arrow. You can't spin the arrow (no rifled barrel), so you will still need fins, but they certainly won't be made from feathers. I'm no aerodynamics expert, but I think funny things happen at supersonic speeds, so I won't give any advice on fin shape. The material will also have to be incredibly stiff to avoid the fin "fluttering."
Then there's the matter of the bow. I tried fooling around with an "[arrow speed calculator](http://archerycalculator.com/estimate-bow-speed/)." I can't ascertain it's accuracy with such large numbers, but using trial and error, it seems to hint that our bow will need a draw weight of around 4500 pounds, or about 2 ton.
I hope your archer is very very strong.
Even with a high draw weight there is the issue of the return speed of the limbs of the bow. This is an issue because the drag acting on the limbs of the bow slow them down, and most materials have a maximum velocity they return to "neutral" at. I'm just going to assume our crazy draw weight somehow overcomes these limitations.
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[Question]
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I'm developing fictional technology for "perfect recycling."
* A large plant that takes in water and every cubic millimeter of waste humanity can produce (in the local area, of course).
* It disintegrates (for lack of a better description) the waste and water. Sea water is used to "balance" the process (to ensure as much mass as the reaction requires is used such that the reaction neither dies for lack of material nor runs away for having too much).
* One output is distilled water, which is used for drinking water, irrigation, whatever might be needed.
* The other output is materialized "goods" such as raw metals, wood (lumber), plastic, chemicals, etc.
*The basis of the story is the political impact of having such a facility in different areas of a future Earth and the corruptible power-grab likely to happen when it is introduced to the world. Can you imagine how the average person living in central Africa would react? or the warlord trying to control said person? Or how the waste management companies of first-world countries would react? or timber and mining companies? But I digress....*
**Question: what technologies today or in the near future could be used to make this recycling plant believable?**
* You might be tempted to believe I'm looking for Star Trek replication and transporter technology. It's the right idea, but not the solution I'm looking for. What my story will have could be considered a very, very early ancestor of such technology. Much closer to us than it is to Jean-Luc Picard.
* Whether one or several technologies, I'm looking for something that can (with a helping of Clarkean Magic) handle everything. An example of the problem is that metals, for example, are easy(ish). Add heat to different amounts and they can be separated. But heat alone would destroy almost everything else and I'm not looking to have to separate the recyclables. Ideally, I am looking for technologies that could lead to molecular disintegration and reintegration.
* While the story will have a plant that enjoys 100% reutilization (no waste products, no toxins unless intentionally produced for resale, etc.), that is obviously not a requirement for any of the supporting technologies I'm looking for.
* I'm looking for suspension of disbelief, but I'm not looking for just anything. The accepted answer should propose technologies that meet the first four bullets along with brief explanations as to why they could support the fictional technology.
* I am looking for more thorough answers than, for example, [the answers to this question](https://worldbuilding.stackexchange.com/questions/22577/weaponizing-the-reverse-assembly-or-partial-disintegration-of-matter) propose.
[Answer]
## Genetically engineered recycling bacteria. Many varieties.
### Plus (perhaps) some new acids to help them along with harder breaking.
The "natural" means of recycling for the Earth is biological decomposition, over time, breaking down compounds for consumption to create animal and plant bodies, which themselves can be recycled as feed for animals.
I have already read several articles in New Scientist, Scientific American and Science News (all magazines dedicated to pure actual science) about bioremediation, bacteria genetically engineered to to digest (break down) crude oil, concentrate radioactive elements from soil, plants that absorb and concentrate salts from soil in their roots or leaves, bacteria that can break down plastics and in turn become food for something else.
Our own gut bacteria (in basically all animals) is secreted by parietal cells in the stomach, for an adult human the product is two liters of hydrochloric acid a day to break down foods. but notice it is secreted by ***cells***, which we can take as proof that engineered bacteria can secrete ***strong acids*** in a slurry tank, that do ***not*** destroy themselves but can break down "garbage".
For a fictional extension of this, presume detailed chemistry and understanding of how to genetically engineer bacteria to produce very specific compounds (like acids and catalysts) advance beyond their current capabilities. (Most of our genetic engineering at this point is learning to cut and paste a gene that exists in one organism, into another organism. We are ***not*** at the point of saying "I want sulphuric acid" and being able to compute, de novo, DNA sequence[s] that will produce sulphuric acid.)
Also, the fictional extension would have to include the idea that there is a reasonably finite number of engineered bacteria that can always get all of the job done, for recycling anything we produce, perhaps in the hundreds or thousands of different bacteria. That is **fictional** because we would need "generalizers", like our own parietal cells producing hydrochloric acid, that will break down large chunks of the millions of compounds we must break down. We don't want **millions** of bacteria for those millions of things.
Now arrange these into a Tree diagram, some hierarchy of treatments in your recycling plant. Each treatment is followed by a sorting of the products produced, different branches of the sorted products undergo more specific treatments, which again are followed by sortings, and more specific treatment.
In our own bodies, the stomach and its strong acid bath and bacteria there dissolve many bonds and turn the food into a slurry. That is then passed to the intestine, where up to **1000 different species** of bacteria go to work processing it, so we can extract nutrients from the slurry. (I am being hand-wavy for brevity, see [Gut Flora](https://en.wikipedia.org/wiki/Gut_flora) for a more detailed discussion.)
So imagine your recycling plant as an engineered digestive system. Imagine that processing tree as being far more complex, to deal with any garbage humans can deliver, including paint and lacquer and used petroleum products, glass and metal, unused (and used) medicines, industrial acids, everything.
Don't imagine ONE magic bullet. I would imagine this plant as a strong acid bath to start that "cleans" incoming garbage, a mechanical chopper that reduce everything to sand-sized particles, more baths, slurries, magnetic fields, etc that sort and process, sort and process, until you are left with things that DO require heat processes (metals and glass at least), and components, concentrated by those thousands of species of bacteria (most of which work in combinations, not alone), that can be turned back into products, fertilizers, ingredients, fuel (e.g. methane) or (through controlled indoor farming) new plant life (to absorb any carbon emitted in the processes).
Note also that heat and cold can be very effective in breaking down products without producing any carbon, both mechanically and chemically. The summer/winter cycle on Earth erodes mountains; water freezes and expands, and can break rocks doing it. You will notice much food with high moisture content (like fruits) become mushy if (at normal below freezing temps) frozen solid and then thawed; their cells were ruptured. "Freezer burn" is a similar process. Freeze and thaw meat several times, and without any bacterial rotting, it becomes very unappetizing. The same thing goes for heat: Cooking food breaks it down (and more digestible and doubles or triples the available calories, which means **easier to digest by gut bacteria**) without burning it.
The recycling plant is a giant digestive process. The majority of this is done just as nature does it, but we don't want to wait centuries for nature to get the job done. We do have some mineral products nature won't break down for many centuries; e.g. stainless steel, glass, mineral crystals (like diamond and sapphire we use). Those should be easy enough to identify and process separately on their own branches.
I would say feel free to add some sophisticated AI (not conscious or self-aware, but chemically all-knowing) to aid the sorting, it could use various testing mechanisms (lasers, sonograms, chemical probes) to decide how to break down some of those sand-sized grains.
Don't think that is too much work: Frito-Lay industries has AI devices that literally examine every single potato chip for discolorations before it goes into a bag, they can make these decisions in micro-seconds and process tens of thousands of chips per second. Your recycling AI can automatically investigate any grain it finds resistant to the mechanical processes, acids or other chemical decomposition processes, or unidentifiable and requiring greater attention, even if there are trillions of those grains per day to focus upon.
Plus it is fiction! The point is that this route is plausible, if only because all of our trash is decomposable some way or another in nature. Special circumstances might fossilize or preserve some things, in sap or bogs or ice or whatever, but your recycling plant is more like the typical course of refuse, or really the worst-possible-case course that causes it to be broken down and reabsorbed as soon as possible in nature. Then amped up by genetically engineered bacteria producing whatever we need to break down the most resistant compounds man has developed.
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I know this is *not* what OP want, but "Easy Way" to have 100% recycling is "simply" to ban any building technology not based on biological processes.
Nowadays "hard to recycle" wastes are due to us using processes unavailable in the normal life cycle (high pressure/temperature, vacuum, etc.), this tends to produce things that cannot be recycled by ecosystem (e.g.: plastic).
OP asks for a generic recycler capable of eating whatever thrown at it; IMHO real answer would be not to produce what can't be readily recycled.
[Answer]
It will need a lot of different technologies and approaches. Goods should be made with the concept of recycling in mind, waste materials should be kept separate where possible and an efficient means of reusing unwanted items need to be introduced. The standard recycling methods can be used for paper, food waste, glass, aluminium, iron and many plastics with waste from these processes being fed into the lower level recycling methods mentioned below.
Once ‘reusables’ have been removed larger items need to be disassembled. Some of the disassembled items might also be reused, for example power supply units, cases etc Once there is nothing left to reuse remaining components can be shredded and further processed to separate smaller components and imbedded items of plastic, metal and glass for recycling as described above.
Remaining material could be burnt at high temperature and the major gasses chemically processed to produce a range of usable raw materials like carbonates and carbon dioxide. The carbon dioxide could be used as a feed stock for plants, or could be further processed chemically as required to make other chemicals by a range of different processes.
Finally there will be a true waste stream of sludge, grim, grot and unusable mixed chemical muck.
This would require a massive amount of energy to process, but I suggest an ultra-high temperature burner could be used to turn the waste into a plasma destroying most chemical bonds. The resulting plasma could then be fed into a very large mass spectrometer like device where the ions in the plasma would be accelerated in a strong magnetic field sorting them by mass/charge.
The ‘detector’ from a traditional mass spectrometer would be replaced by a wide range of collectors where individual elements would accumulate. These relatively pure elements could then act as feed stock for manufacturing.
The trick with making this work would be to ensure that the waste stream for the last stage was as small as possible and there was a sufficiently large supply of energy to power it all.
[Answer]
How about simply having nanites that break things back down to the simplest state for re manufacturing? You could have them only work on inorganic matter as a safety precaution. They could be powered by something green like solar power.
I read somewhere about nanites that could literally mine for things like gold molecule by molecule. Imagine what that could do once refined and perfected? I also imagine powering them by a field of electromagnetism so they could only work in a limited area. You could set it up in a junk yard where there's already so much stuff.
Although, I have to say practically that no system would reuse 100% all of what's put into it. Something has to be spent and can't be passed on, or at least not for a very long time. We take in carbon through the carbon cycle. How long do you think it takes every single molecule to leave you, excluding death?
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You are aiming to 100% recycling. This means you want to decompose any object into its prime constituents, which are currently chemically bound into the to-be-recycled object.
You need to:
1. break the chemical bonds to free the atomic species: this can be done by provide enough energy, aka heat it up a lot until it is some sort of plasma.
2. prevent that other unwanted chemical bonds are created between non similar species.
3. bucket the species separately (Nitrogen with Nitrogen, Gold with Gold, you name it...)
4. lower the energy of the buckets so that chemical bonds can be formed again: here is you can use water, which is a good coolant. Sea water evaporates and cool, and upon condensation it has lost all its salts.
5. harvest the materials and use them at will.
[Answer]
@Slarty has the right idea. Some embellishments:
* Lots of standardization of commodity items -- containers etc that allow reuse.
* Requirement that manufacturers design products to be recycled. This can be done in various ways:
+ Devices are held together with solvent soluble connectors.
+ Conventional metal connectors.
+ Standard component materials mixes that are easily separated.
+ Use of tags in materials to facilitate rapid mechanical separation.
* As a source of energy, use magneto/hydro dynamic fusion generators. You need to make the plasma conductive to use MHD anyway. Temps are high enough to vaporize everything. At the output end, use the equivalent of a mass spectrometer to separate ions by charge/mass ratio.
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[Question]
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Assume Earth of today was altered overnight.
Some percentage of the more common elements of Earth's bulk (silicon, iron, and so on) are replaced with something much heavier. This changes the over mass of Earth and its gravity increases according.
How much of a change to gravity would it take to cause an extinction level event for the higher lifeforms? In other words, no need to worry about microorganisms as they may not notice.
[Answer]
The main cause of extinction will not be direct effect on biology but geophysics. A higher gravity changes many aspects of the geosphere, oceans and atmosphere.
The big one is suddenly increased pressures in the geosphere. Even if the change in gravity is small it would likely both trigger earthquake faults and more importantly, volcanism. Large magma chambers would suddenly be under significantly more pressure and the strength of the rock above would not have increased: expect at least numerous synchronous volcanic eruptions. It is not implausible that this might include supervolcanism, in which case we easily get a basic mass extinction. This volcanism not just a quick transient since the change would also make mantle plumes much more vigorous, leading to a long-term increase in plate tectonics and eruptions.
The fundamental reason for this is that buoyancy forces are due to a density difference times gravity: $F=g(\rho\_{heavy}-\rho\_{light})$. Boost gravity and they become proportionally stronger.
This also affects the atmosphere. Surface pressure goes up a bit. Convection will become more vigorous since the density changes due to temperature gets multiplied by a stronger gravity. Hence the weather and climate will change in complex ways. Exactly how is a bit hard to tell without simulation. One obvious effect is that the scale height will be reduced: pressure will decrease faster at high altitudes (it will be $7400 (g\_{now}/g\_{changed})$ meters), changing the stratosphere and likely the size of the Hadley convection cells (several factors working against each other there; I think they will become proportionally broader, meaning that the current 30 degree size might shift to a 45 degree size with a very different climate distribution).
A lot of mountains and continental slopes will become unstable since they will have a flatter angle of repose, so there will be lots more landslides, seaslides and erosion. That likely also includes a lot of glaciers and ice shelves.
The moon would get a tighter orbit, likely more elliptical if the change was sudden. That would make tides slightly stronger.
In short, I think a few percent extra gravity might be enough to cause a mass extinction even though most animals would not even notice the extra gravity. The disaster effect would just be a combination of simultaneous (super)volcanism, a reorganisation of the climate zones, and instability of a lot of material on continental shelves.
[Answer]
You've said "over night" I'm going to take that as meaning a more or less immediate effect. You haven't set a time limit on extinction though so there are two scenarios I see A. you want everything bigger than a dog dead instantly or B. you want an actual mass extinction event which will play out over a short but geological timespan.
To get option A. you need something over a 100 fold increase, this will give you a 100g "shock load" across the board, that's long been considered the instant death threshold in crash testing for humans. I'm assuming there are animals that can handle more than we can though so I'd make that the lower limit for scenario A. This absolutely will *pancake* every building on Earth and most of the vegetation too. This is a level of gravity is likely to eventually kill everything on Earth as the resultant pressure will break down protein synthesis pathways as well. I don't think this can be done the way you're thinking though, it's just too big a jump, in mass and more importantly *density* the words "[degenerate matter](https://en.wikipedia.org/wiki/Degenerate_matter)" come to mind.
Scenario B. is a lot harder to quantify, there are flying insects that are vital to the ecosystems that virtually all animals rely on that could probably be grounded and whipped out by the atmospheric effects of a tiny change, we wouldn't notice the difference except experimentally, just all the flies and bees etc... disappearing and the crops failing, even corn and other wind pollinated species would suffer from a small shift in air density caused by increasing or decreasing gravity. I can't even guess at this one.
The above is focussed on land animals only, sea life is a different story, many shallow water fish (shallow by habit not depth of the underlying ocean) would have trouble as the air/water density ratio will be shifted by a change in gravity and air density at sea level; this will effect buoyancy and dissolved gas levels. Deep water fish will have far less of a problem and fish without swim bladders, like sharks and rays will only have issues with the gas dissolution. What it would do to the [Cetacea](https://en.wikipedia.org/wiki/Cetacea) is anyone's guess.
Do note that any elemental substitution effecting the [Crust](https://en.wikipedia.org/wiki/Crust_(geology)) of the Earth is going to have immediate and drastic consequences for all life due to poisoning/imbalance effects. As I pointed out in the comments if you switch out any noticeable percentage of the Iron in steel framed buildings for something bigger, and heavier, like Lead you are inviting catastrophic failure. This is true of any alloy or composite material, including concrete both the cement and the aggregate phases. If you the replace Silicon in the [Ogallala Aquifer's](https://en.wikipedia.org/wiki/Ogallala_Aquifer) sand with heavy metals you could poison *millions* of acres of pump irrigated farmland.
[Answer]
I never played with animal in a centrifuge to see how they react to increased gravity, nor I am aware of any studies doing this (probably because putting an elephant for days or months into a centrifuge would certainly be awarded an IgNobel), but I can still try to draw some parallel with what we know about effects on human body.
When you increase gravity, the first effects will be:
* increased effort to pump blood against the gravity field (a.k.a. up)
* increased load on limbs to sustain the body
* increased effort on moving against the gravity field
All these (especially the first two) are likely to generate long term issues (cardiovascular stress, increased wear on joints, etc.) which will shorten lifetime. But this alone won't lead to extinction, as long as the birth rate is still decent.
Then it comes the question on how gravity affects embryo's growth. Again, as far as I know nobody ever put any (big enough for the scope of your question) animals in a centrifuge for long enough to have mating and successful pregnancy carried over. I suspect that increased gravity will surely affect the development of the embryo, resulting in increased miscarriage.
As you can guess, it is likely that there is no sharp threshold for gravity lethality. It is more a fuzzy change from the "business as usual" at 1 g to the "flat day, isn't it?" at black hole level g.
To make a parallel, consider obesity: being overweight is known to increase the chances of pathologic conditions, but being 10% or 100% above ideal weight are two different games.
[Answer]
I think this is a multifaceted question, that needs an answer for each animal or plant type. So I'll consider humans as the main case then breify a few other examples.
**Humans**
If the increase was substantial, say greater than 2g, I doubt that any humans would survive for long. A few hardly individuals might last a few weeks or even a few months but the casualty rate would be terrible. Older people often break bones when they fall, in part because they can’t react quickly enough and in part because their bones are weaker than those of younger people. In a 2g environment even the young would suffer these problems because their reaction times would have to be so much faster to prevent damage (by extending arms etc) and the increased speed of impact would make their bones more likely to break.
At 1.5g it’s a tougher call, but I suspect not in part because of the reasons given above for 2g conditions, but also because of the break down in society caused by multiple dislocations to civilization. Huge numbers of people in hospital due to fractures and many other complaints exacerbated by the increased gravity eg asthma. Any mechanism that relied on gravity in any way might change its behaviour or stop functioning. Such things might be hard to predict but would range from the inconvenient to the seriously damaging for example doors becoming jammed or hard to open, most, if not all, planes grounded and many plants like modern wheat ending up bent over and hard to harvest.
So at 1.5g I would say it’s borderline but non-survivable due to general collapse. Much less than that I think it’s survivable by at least some for years.
At 1.2g I suspect a lot would survive for long enough to ensure the continuity of the species. The young would have the advantage (if that’s the right word) of growing their bodies in the new gravity so would almost certainly be better adapted than their parents even without any genetic adaption. Beyond that natural selection would ensure that those best capable of adapting would survive in the greatest numbers and the human genome would be whittled down a fair bit (less tall people more short people etc) leaving just the fittest.
Over the longer term evolutionary adaption by mutation would become an important factor but might take hundreds of thousands of years.
**Birds**
Birds are much more vulnerable to gravitational issues and would be seriously affected by any change more than a few percent with the heaviest birds suffering most. It is very hard to say exactly but I would estimate somewhere between 1.05 and 1.1g would see off all flying bird species.
**Fish**
Fish should be less affected due to buoyancy, but might still struggle with swim bladder issues. 1.5-2g?
**Plants**
Large species or those with fine structures would be seriously affected and would be first to go the more sturdy squat varieties would last longer and ground hugging species would survive longest.
**Lower forms**
Things like algae, lichen, plankton and bacteria would all be affected but should be capable of withstanding much higher g forces. It is hard to predict but I suspect 5-10g would kill many even of these species. The ultimate survival limit is almost impossible to say as the world would be a very different place.
Edit
**Evidence and references**
There is some information of interest in these references
<https://space.stackexchange.com/questions/6154/maximum-survivable-long-term-g-forces>
<https://standards.nasa.gov/standard/nasa/nasa-std-3001-vol-2>
[https://www.amazon.com/Biology-Human-Survival-Extreme-Environments/dp/0195165012](https://rads.stackoverflow.com/amzn/click/0195165012)
But I doubt that there is any really hard evidence available because the situation is inaccessible to any form or simple experiment. So this is a matter of opinion to some degree. Although the g forces quoted in the second reference might appear to suggest that 4g is doable, bear in mind this is for astronauts in acceleration couches. Not for joe public trying to do his shopping and climb stairs etc.This reference tends to support my view about injury (page 53). I would suggest this is especially true when not lying on an acceleration couch.
“During dynamic flight phases, there is potential for impact and flail injury, which includes crewmember extremities impacting vehicular surfaces or objects, hyperextending, hyperflexing, hyper-rotating, fracturing, or dislocating if proper restraints and supports are not used. Features such as harnesses, form-fitting seats, and tethers may help maintain the proper position of the crewmember's body and limbs to reduce movement or contact with vehicle surfaces that would produce injury. In addition, the design of spacesuits may contribute to reducing injury to the crew. Preventing the inadvertent contact of extremities with vehicular structure or interior components significantly reduces the likelihood of limb fracture or soft tissue injury during a dynamic flight event. Extremity guards, tethers, garters, and hand holds have been used to reduce injury in other spacecraft, aircraft, and automotive vehicles”
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[Question]
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I've been working on a story in which the main setting is basically a canyon around a river (like the Grand Canyon, I guess), but it's specifically where the river meets the sea, and it's still in the canyon.
Does anyone know if this is geographically possible/present in the real world, and if so if there are any places you can give me where it is true so I can get google earth references?
[Answer]
The term you are looking for is [fjord](https://en.wikipedia.org/wiki/Fjord).
A fjord is defined by Wikipedia as:
>
> A long, narrow inlet with steep sides or cliffs, created by glacial erosion.
>
>
>
If a river flows into the fjord it should be the sort of geographic feature you are looking for.
[Answer]
A canyon is just a narrow and deep river valley, often produced when a plain was eroded by a passing river after it had been lifted. A fjord (as proposed by Sphennings) is a river valley flooded by the sea, either due to rising sea levels or to falling land levels. What the question proposes is just a canyon flooded by the sea.
It's debatable if Norwegian fjords qualify as canyons. Probably, if we could see them with water at a lower level we would call the narrowest and deepest of them canyons.
We would see a more spectacular example of a flooded canyon if the sea level rose (or the Colorado Plateau sank) by several hundred meters to flood the bottom of the Grand Canyon. Although unlikely in the foreseeable geological future, it would be a great fit for the question.
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[Question]
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Where would large amounts of food be stored in a medieval setting? For example stockpiling for winter.
Would there just be one large place to store all food, like a cellar, or would different foods be stored in different places? I'm looking for the name of these places and what can be stored in each.
My continent is loosely based on England between 1100 and 1200 AD.
The seasons would play a large factor in deciding what storage is most suitable for each food.
Each season is similar to the location and time period, but they have been amplified, for maximum effect.
Winter is like an Arctic winter, and summer reaches temperatures of the Sahara, at its peak.
Spring and Autumn are transitional seasons with both being quite wet. Spring starts off cold and gets warmer. The opposite is true for the autumn.
Magic is out of the question for now as it is going to be discovered, but it hasn't happened yet.
I've tried searching the web for an answer but keep getting preservation methods and not where the food (preserved or not) would be stored.
[Answer]
Generally, food storage is located in rooms in a castle or other fortified building because otherwise bandits and neighboring feudal lords would steal it and everyone in the victimized fiefdom would die.
Grain storage is usually in a tower-like silo or other granary. Root vegetables are stored in cellars (often called root cellars or dugouts). Preserved meats, seeds, and picked goods are stored in storage rooms or small warehouses. Hay and other cattle feed is stored in barns or stables, often in tied hay bales or barrels or casks. You might want to look at architectural drawings for medieval castles and manorial estates to get a feel for what these areas were called, and how many of each were present.
But, keep in mind that in most medieval settings that food storage was not very viable for many kinds of foods. Many communities lacked any capacity to freeze or refrigerate food produced in warmer months (like fresh fruits, fresh vegetables and fresh meat) for the winter, hunting as well as gathering of edible plants was much less abundant in the winter, and caloric consumption typically went way down in the winter as people went a little hungry and tried to cope by being less active - a situation that continued through the spring when the first new crops would be available.
Bread made from flour (that could be preserved and stored) in casks in a storage room or in part of the mill where it was ground; water; local alcoholic beverages in wooden or ceramic casks, in bottles, in leather skins, or in ceramic beakers; small portions of meat that could be preserved with salt or vinegar in barrels or ceramic or glass or leather containers, together with potatoes and onions stored loose in bins or fiber bags in a root cellar, and milk from dairy cows or goats that were kept in a barn (including cheese from their milk which lasts a little longer depending on how dry the cheese is) would typically be the main sources of winter food.
Because food storage was poor, you tried to have kids in the spring so that infants would be mature enough not to die of malnourishment when winter arrived and reduced food for a breast feeding mother reduced nourishment available for the breast feeding child.
[Answer]
From the article [Medieval Food Preservation - Keeping Food Edible for Months or Years during the Middle Ages](https://www.thoughtco.com/g00/medieval-food-preservation-1788842?i10c.referrer=https%3A%2F%2Fwww.google.be%2F) :
>
> ### DRYING FOODS TO PRESERVE THEM
>
>
> Today we understand that moisture allows for the rapid microbiological
> growth of bacteria, which is present in all fresh foods and which
> causes them to decay.
>
>
> But it isn't necessary to understand the chemical process involved in
> order to observe that food that is wet and left in the open will
> quickly start to smell and attract bugs. So it should come as no
> surprise that one of the oldest methods of preserving foods known to
> man is that of drying it.
>
>
> Drying was used to preserve all sorts of foods.
>
>
> Grains like rye and wheat were dried in the sun or air before being
> stored in a dry place. Fruits were sun-dried in warmer climes and
> oven-dried in cooler regions. In Scandinavia, where temperatures were
> known to plunge below freezing in the winter, cod (known as
> "stockfish") were left out to dry in the cold air, usually after they
> were gutted and their heads were removed.
>
>
> Meat could also be preserved through drying, usually after cutting it
> into thin strips and lightly salting it. In warmer regions, it was a
> simple matter to dry meat under the hot summer sun, but in cooler
> climates, air drying could be done at most times of the year, either
> outdoors or in shelters that kept away the elements and flies.
>
>
> ### PRESERVING FOODS WITH SALT
>
>
> Salting was the most common way to preserve virtually any type of meat
> or fish, as it drew out the moisture and killed the bacteria.
> Vegetables might be preserved with dry salt, as well, though pickling
> was more common. Salt was also used in conjunction with other methods
> of preservation, such as drying and smoking.
>
>
> One method of salting meat involved pressing dry salt into pieces of
> meat, then layering the pieces in a container (like a keg) with dry
> salt completely surrounding each piece.
>
>
> If meat was preserved this way in cold weather, which slowed down the
> decomposition while the salt had time to take effect, it could last
> for years. Vegetables were also preserved by layering them in salt and
> placing them in a sealable container such as an earthenware crock.
>
>
> Another way to preserve food with salt was to soak it in a salt brine.
> While not as effective a long-term method of preservation as packing
> in dry salt, it served very well to keep food edible through a season
> or two. Salt brines were also part of the pickling process (see next
> page).
>
>
> Whatever method of salt preservation was used, the first thing a cook
> did when he got ready to prepare the salted food for consumption was
> soaking it in fresh water to remove as much of the salt as possible.
> Some cooks were more conscientious than others when it came to this
> step, which could take several trips to the well for fresh water.
>
>
> And it was next to impossible to remove all the salt, no matter how
> much soaking was done. Many recipes took this saltiness into account,
> and some were designed specifically to counteract or complement the
> salt flavor. Still, most of us would find preserved medieval food much
> saltier than anything we're used to today.
>
>
> ### SMOKING MEAT AND FISH
>
>
> Smoking was another fairly common way to preserve meat, especially
> fish and pork. Meat would be cut into relatively thin, lean strips,
> immersed briefly in a salt solution and hung over a fire to absorb the
> smoke flavoring as it dried -- slowly. Occasionally meat might be
> smoked without a salt solution, especially if the type of wood burned
> had a distinctive flavoring of its own. However, salt was still very
> helpful because it discouraged flies, inhibited the growth of
> bacteria, and hastened the removal of moisture.
>
>
> ### PICKLING FOODS
>
>
> Immersing fresh vegetables and other foods in a liquid solution of
> salt brine was a fairly common practice in medieval Europe. In fact,
> although the term "pickle" didn't come into use in English until the
> late Middle Ages, the practice of pickling goes back to ancient times.
> Not only would this method preserve fresh food for months so that it
> could be eaten out of season, but it could infuse it with strong,
> piquant flavors.
>
>
> The simplest pickling was done with water, salt and an herb or two,
> but a variety of spices and herbs as well as the use of vinegar,
> verjuice or (after the 12th century) lemon led to a range of pickling
> flavors. Pickling might require boiling the foods in the salt mixture,
> but it could also be done by simply leaving the food items in an open
> pot, tub or vat of salt brine with the desired flavorings for hours
> and sometimes days. Once the food had been thoroughly infused by the
> pickling solution, it was placed in a jar, crock, or other airtight
> container, sometimes with a fresh brine but often in the juice in
> which it had marinated.
>
>
> ### CONFITS
>
>
> Although the term confit has come to refer to virtually any food that
> has been immersed in a substance for preservation (and, today, can
> sometimes refer to a type of fruit preserve), in the Middle Ages
> confits were potted meat. Confits were most usually, but not solely,
> made from fowl or pork (fatty fowl like goose were particularly
> suitable).
>
>
> To make a confit, the meat was salted and cooked for a very long time
> in its own fat, then allowed to cool in its own fat. It was then
> sealed up -- in its own fat, of course -- and stored in a cool place,
> where it could last for months.
>
>
> Confits should not be confused with comfits, which were sugar-coated
> nuts and seeds eaten at the end of a banquet to freshen the breath and
> aid the digestion.
>
>
> ### SWEET PRESERVES
>
>
> Fruits were often dried, but a far more tasty method of preserving
> them past their season was to seal them up in honey. Occasionally,
> they might be boiled in a sugar mixture, but sugar was an expensive
> import, so only the cooks of the wealthiest families were likely to
> use it. Honey had been used as a preservative for thousands of years,
> and it wasn't limited to preserving fruit; meats were also stored in
> honey on occasion.
>
>
> ### FERMENTATION
>
>
> Most methods of preserving food involved stopping or slowing down the
> process of decay. Fermentation accelerated it.
>
>
> The most common product of fermentation was alcohol -- wine was
> fermented from grapes, mead from honey, beer from grain. Wine and mead
> could keep for months, but beer had to be drunk fairly quickly. Cider
> was fermented from apples, and the Anglo-Saxons made a drink called
> "perry" from fermented pears.
>
>
> Cheese is also a product of fermentation. Cow's milk could be used,
> but the milk from sheep and goats was a more common source for cheese
> in the Middle Ages.
>
>
> ### FREEZING AND COOLING
>
>
> The weather of the greater part of Europe throughout much of the
> Middle Ages was rather temperate; in fact, there is often some
> discussion of the "medieval warm period" overlapping the end of the
> Early Middle Ages and the beginning of High Medieval Europe (the exact
> dates depend on who you consult).
>
>
> So freezing was not an obvious method of preserving foods.
>
>
> However, most areas of Europe did see snowy winters, and freezing was
> at times a viable option, especially in northern regions. In castles
> and large homes with cellars, an underground room could be used to
> keep foods packed in winter ice through the cooler spring months and
> into the summer. In the long, frigid Scandinavian winters, an
> underground room wasn't necessary.
>
>
> Supplying an ice-room with ice was a labor-intensive and sometimes
> travel-intensive business, so it was not particularly common; but it
> wasn't completely unknown, either. More common was the use of
> underground rooms to keep foods cool, the all-important last step of
> most of the above preservation methods.
>
>
>
[Answer]
Smoked and salted meats have been around for a very long time. Many times in our history salt was worth its weight in gold because it was so rare to find in nature. [The salt trade](https://en.wikipedia.org/wiki/History_of_salt) also started many wars.
[Grain Silos](https://dl.sciencesocieties.org/publications/aj/abstracts/12/5/AJ0120050175?access=0&view=pdf) have been around for well over 2000 years.
[Caves](http://www.wookey.co.uk/cave-aged-cheese/) were used quite a bit to preserve food and is still in use today for artisan cheese crafting.
] |
[Question]
[
I watched Independence Day: Resurgence the other day. In it, Earth's first line of defense is a lunar base (that gets blown up), followed by an orbital satellite network (that gets blown up).
Now, assuming a sufficiently advanced society that can construct large scale installations in orbit, would a lunar base be redundant?
A military base may be limited, as the moon's rotation is negligible and it will be in a "fixed" position, relative to the Earth, making it easy to bypass. For commercial usage, I see a similar issue with its positioning.
Prior to the ability to produce large scale facilities in orbit, a lunar base may prove useful, but afterwards, could it prove of any real use? (Aside from the tides and stabilizing the Earth's orbit)
EDIT: Could the base be salvageable? Could there still be a use for it, or should it just be stripped for materials?
[Answer]
It's depends but **YES**.
## Military reasons
Military usefulness depends on threats. If headquarter decided that
* orbital base is hard to protect but easy to see
* aliens could silently concetrate on backside of the Moon
* one line of defence is not enough
* we need outpost
* etc etc
then they would want to build lunar base.
## Economical reasons
* for some reason use of intermediate base is better than direct transport to long-ranged orbital equipment (radiation issues, operation time, possibility to service manipulations)
* mining ice or another resources at the Moon is cheaper than mining on Earth **and then deliver to the orbit**
* Any satelite needs engines and navigation equips just for keep a stable orbit. On the Moon it's not an issue although there are other problems.
+ Communication hub on the moon is an option
+ but interstellar telescope is impossible (for now) because precise details couldn't survive landing
[Answer]
# Yes, base on the moon is useful.
Main commercial reason to have the moon base is the difference in cost lifting the matter from earth compared the same from the moon.
It is not only 12 times cheaper energy-wise if you use non-rocket launch systems but the complexity and costs(energy and labor) involved in building such non-rocket launch systems (mass drivers or anything you may wish) on the moon compared to any other body in solar system.
No, the base it not obsolete after the interplanetary infrastructure is established.
Moon is a big possible source of main construction materials which we use today
* Iron, Aluminium, and others. The may lose their significance, but still, they are possible building materials, which can be used
The most importantly it's close to the Earth. Proximity to earth means fewer delta-v requirements for delivering the materials for any construction you would like to build near Earth or in Sun-Earth L1, L2 points, especially with mass drivers. And as long as there more people on Earth than in other places in space, demand for those constructions here will be more than in any other place, especially because building those constructions can be useful for Earth climate maintenance, energy supplies etc.
Generally speaking there no a lot of possible alternatives for the moon. Asteroids - water(hydrogen), nitrogen, carbon, construction materials. Venus - carbon. Jupiter and its moons - hydrogen, carbon, nitrogen construction materials. Mars - construction materials(con - atmosphere and genetically modified Martians dreaming about terraforming). Mercury - construction materials(small con - high delta-v requirements). So even with infrastructures on all those bodies, the significance of moon will be reduced, but not vanish.
[Answer]
These are some of the **advantages** of a moon base over an orbital base:
1. **Camouflage**: You can attempt to hide a base on the moon, because the moon is pretty big, and people expect it to be there. An orbital base is more difficult to hide.
2. **Armor**: The surface of the moon is covered in craters, due to constant bombardment by rocks and ice travelling at up to orbital speeds. An underground moon base could be protected from this bombardment - and also from most weaponry (if they come with planet busters, your station doesn't matter anyway). This will also help with protecting a crew from radiation.
3. **Gravity**: On the moon you don't need artificial gravity to stop everything from floating around. This is quite neat, when it's a manned station. On the other hand, lower gravity and lack of athmosphere means you can launch small craft quickly and easily - something a planetary base cannot provide.
4. **Mass of the moon**: Your station will likely have a mass lower than the moon. Using an orbital space station to fire rail guns at an adversary, would change it's orbit. You would be limited to smaller, recoilless weaponry in most cases. The moon is a convenient emplacement for your heavy interplanetary artillery.
5. **Less collateral damage**: Any shot that would miss an orbital defense station, could hit the nearby planet or be drawn into its gravity well, making for potentially devastating collateral damage, even from an unsuccessful attack on a military installation. The moon is more likely to provide a buffer for destroyed craft and malfunctioning/misaimed weaponry, where it wouldn't impact a planet's fragile ecosystem.
So, *unless your base is the size of an Imperial Death Star*, you would do well to keep it under the surface of the moon.
As an advance outpost, a base on Pluto or similar sized rim-planet would be pretty neat, but out there you wouldn't be able to rely on solar power as much (at least for day-to-day operations), as on the moon, so you'd need either another locally available power source, or ship fuel out there every so often.
My assumptions are of course only valid, if the moon in question is similar to the Earth's moon, and generally considerd inhabitable, with significantly lower gravity than a reasonably nearby planet. In a solar system with inhabited moons around a gas giant, you would probably want to have your defensive perimeter outside the planet's gravity well.
[Answer]
Remember space is big and empty. And yes, I know you think you know what that means. You don't. Space is bigger than you think. The human brain is not built to conceptualize something as big and empty as space. In scifi movies, we often have images of ships dogfighting and basically acting as souped up WW-2 battles. That's unlikely. Unless you are talking about some kind of sneak attack, the battles will probably be waged from a pretty far distance. So even if the enemy attacks from the far side of Earth, whatever defenses the moon base might have would have plenty of time to get on an intercepting orbit.
Also don't forget about ammunition. Rock could easily be mined locally from the moon to create munitions, whereas the space station would have to have it transported from somewhere else.
Finally the moon has inertia. Depending on the enemy's orbit, whatever you are firing may need quite a bit of delta-v to intercept it. If you are using rockets, that's fine as long as you are ok with wasting a lot of fuel. But a moon base would allow you to build some sort of rail gun or other ballistic weapon to give it the bulk of the acceleration. The space station would not be able to do that without Newton's third law mucking up it's orbit after enough rounds.
] |
[Question]
[
In the near future mankind could well permanently settle on the Moon.
Whether for research or mining or just good old fashioned novelty is irrelevant.
The colony includes:
* Large domed structures for farming and recreation. The largest dome on Earth (according to Wikipedia) is the [Singapore National Stadium](https://en.wikipedia.org/wiki/List_of_largest_domes) coming in at 310 m (1017 ft) in diameter. With the reduced gravity and potential advances in material sciences, I am going to place the diameter of the domes at 1000 meters (3280 ft). There are currently 20 domes, spaced roughly 2 miles apart (each is at least 2 miles from any other dome).
* Underground domiciles form the majority of living spaces.
Most domicile spaces are 3.65M × 3.65M (12 ft × 12 ft) and house two people per room. There are 12,000 people on the Moon colony.
* A central command center, which also serves as a hardened evacuation site in the event of some catastrophic event – a meteor strike, perhaps. The command center cannot hold more than 2,500 people.
How would you manage the transportation of goods and people with this setup?
**I am primarily looking for methods of travel that make use of the reduced gravity to move things differently than on Earth.**
A more specific bonus question...could you make the tube system work for humans?
[](https://i.stack.imgur.com/ThrwO.jpg)
[Answer]
The answer is: **trains carrying containers**, just like we do it on Earth. Trains might seem boring and not very sci-fi, but they are actually super bad-ass and very sci-fi for a number of reasons:
**SIMPLE IS GOOD**
The general rule with engineering is 'less moving parts'. Trains are extremely straight forward and very well understood. They run in **one** dimension only, forward and backward, reducing the complexity of transport compared to other vehicles by multiple magnitudes. Compare them to ground vehicles, that run in two dimensions, or air vehicles, that run in three, and you start to magnify the complexity of moving something from one place to another exponentially. Also Moon bases will likely be fairly static; its not like you can just go start a village somewhere, so the loss of freedom from moving on a single plane is not that much of a big deal.
The benefits of working on only one dimension cannot be stressed enough, it eliminates SO many engineering problems its not even fair to compare them to other transport types. At a basic level, trains are three components: a drive wheel, engine and battery. This simplicity makes repairs and maintenance easier and more accessible to more people, which is good in an environment like the moon where help (ie. Earth) is always far away.
Trains are highly reliable, efficient and can move huge volumes with minimal oversight and energy expenditure. While some deliveries on Earth require planes, drones or couriers to do last mile fast deliveries, 95% of transport is slow and planned weeks in advance, and being on the moon wouldn't change that. Food, supplies, oxygen and water needs to be able to be moved around *in volume*, over and over again. One of the rules of good design is 'don't solve problems you don't have', so trains fit the bill here quite well.
Another important factor is that, unlike newer technology, trains can be easily automated to run 24/7 without any risk of human error. This means trains can operate in a vacuum without any risk to drivers. Even the loading and unloading can occur automatically, in multiple airlocks to move from vacuum to pressurized without any risk to the integrity of the station. All of this is existing, proven technology, which is very important when attempting anything in a new environment; in a vacuum everything needs to be simple, clear, easy to use and understand. The less time you spend trying to invent new technology, and more time you spend coming up with weird ways your current tech could catastrophically fail and fix it, the better.
**SAFETY IS PARAMOUNT**
In terms of safety, trains also win hands down. Even on earth, the dominant factors in our choice of transport is **safety** and **cost**. If given a choice between a ride in a train to the center of your local city and hiring a helicopter to pick you up from your backyard, I know which one the average Earth resident would choose. If given a choice between hurtling at 700km/h across the moonscape in a tube, inches from a deadly vacuum and sitting safely in a cheap ass train, I know which one moon travellers will choose.
Humans are irrationally risk averse, and like to tell scary stories to themselves, even when the data demonstrates otherwise. The classic example is air travel, which is incredibly safe statistically, but lots of people are still afraid of flying. So they get in a car and drive it themselves, which is incredibly dangerous, but its not about what the technology IS, it's how its PERCEIVED. So while new transport methods might be very safe in principle, I find it hard to believe that humans will just get in board all at once, especially when there are safer modes available that give more PERCEIVED control over their own personal safety.
Then consider that every scrap of material up there either has to be transported from earth or synthesized from moon rock, and you end up with Occam's Razor cutting out almost everything by the cheapest, most efficient solutions that do the job and nothing more.
Also from what I have heard from astronauts on YouTube, the vacuum of space is freaking terrifying. It is like living in a world filled with sarin gas, and the slightest crack in a window or opening the door the wrong way will kill you and everyone you love. You can't ever, ever make assumptions or cut corners with technology, because then you die. This is a mantra often seen in divers or parachutists, because they live with real danger every second they are in that environment. I would be prepared to bet that on the moon that no-one will ever go anywhere in anything but the slowest, safest mode of transport possible, because they live in perpetual danger of turning into Total Recall Arnold.
**INERTIA IS A BITCH**
In close to zero G, the biggest danger is not going fast, its not being able to stop. On Earth, we can rely on gravity to provide natural fail-safes; if something is going too fast, then at some point it will fall to the ground and lose its inertia almost immediately through friction. If you stop providing power, gravity will hold your wheels to the ground for you. Even if you hit something, and break up, all those bits eventually hit the ground and stop moving. So will the things you hit, and so on.
This is not the case on the moon, without gravity or an atmosphere to slow things down, turning all moving objects into deadly weapons. For example, a vehicle or space craft which loses power en route is not just stranded in the middle of a moon wasteland; they are a bullet targeted *straight at their destination* with no means of stopping. There's not much you can do to deflect their path short of shooting them into pieces, which themselves might just become more bullets. The things those bullets hit become more bullets, and so on forever.
For the reason above, trains are the best solution. They are/can be stuck to rails on the ground through physical means, to prevent them going AWOL. Contact with the rails ensure they have a means of generating friction should something go wrong. Even trains on earth have dead-man switches, and trains on the Moon would be no different. Their fixed nature makes it trivial to put in guards or barriers to prevent shrapnel spreading in the event of a crash. When you put the brakes on, you are slowing down the whole train equally. And you always, always always know where they are pointed, and where all the bits might be able to go. That allows you to practice good design and set up entire transport routes and facilities to mitigate risk, reducing the risk of bulletisation to zero (a good number).
**LOADING / UNLOADING**
One of the most overlooked factor in the efficiency of transport is not the miles per gallon of the vehicle, but the time spent loading and unloading. Goods in a container might spend a week on a boat going from China to the US, but they spend another week or more sitting in docks, being shuttled around and stored safely. The energy invested in manning, operating and organisation the docks and workers on the ends of transport routes heavily outweighs the actual hauling costs. So you should design you transport solution to fit your logistics, not the other way around.
Containers on trains are one of the fastest, most efficient ways of getting goods on and off a vehicle; if you have ever played *Factorio*, you will see a basic example of how straight forwards. Train comes in, all containers replaced in ONE swift action, train leaves, repeat. Again, their one dimensional nature makes the entire operation *technically simple*, which is great.
This is also made easier by the fact that the Moon has little to none of the space and storage concerns we have here on Earth that can make higher density transport options more economically viable. You can just stick and stack containers anywhere in a vacuum, they aren't going anywhere.
**IN SUMMARY - TRAINS ARE SICK**
All in all, old fashioned rail trains are the perfect vehicle for an environment where safety, reliability and efficiency is everything. You might be tempted to try and impress your audience with fancy transport options, but like so many thinks in life the stuff we use right now is METAL AS F\*\*K when you really drill down into it. It's up to you to sell the story to your audience in an engaging way. I am sure than when we end up going to space properly, we would build nothing but trains everywhere if we could.
**EXTRA PERSONAL OPINIONS**
As a species we are driven primarily by a desire for efficiency and safety; how much can we get done with our limited brains and muscles, without getting ourselves killed, so we can chill out as much as possible. I think good science fiction should reflect that sentiment and some of my favourite sci-fi books are the ones where there are no flying cars, magical transport tubes or fancy AI bullshit that just makes things happen. They are filled with technology that seems designed to fulfill a **function**, not impress the reader. They are a vehicle for the desires and needs of the characters. I am more impressed by an author that seems to have understood her setting and done the research to fit it than those who want to talk about killer robots and then McGuffin their way to it. That's lame.
[Answer]
# Maglev Trains
They wouldn't worry about a piffling thing like gravity
[](https://i.stack.imgur.com/7DEls.jpg)
>
> The principle of magnetic levitation is that a vehicle can be suspended and propelled on a guidance track made with magnets. The vehicle on top of the track may be propelled with the help of a linear induction motor. Although the vehicle does not use steel wheels on a steel rail they are still referred to as trains as by definition they are a long chain of vehicles which travel in the same direction. This is the definition of a MAGLEV train.
>
>
>
[](https://i.stack.imgur.com/Aj3aJ.gif)
[Image Sources](http://www.circuitstoday.com/working-of-maglev-trains)
So, being magnetically linked to the rail (and anchored) prevents gravity from being an issue. Lower gravity should make them more efficient, I expect...
Interior view:
[](https://i.stack.imgur.com/fx1zY.jpg)
[Answer]
# No need for rails on the moon.
One option is a suborbital mass driver.
You take a mass driver that can accelerate a payload very precisely.
[](https://i.stack.imgur.com/IfZgh.gif)
You could use it to get payloads into orbit. But another option is to fire payloads to a destination.
[](https://i.stack.imgur.com/ckXWq.jpg)
You don't need to worry about atmosphere or wind since the atmosphere is extremely thin, barely there. So there's almost no drag.
You can then "catch" the projectile as it enters the mouth of another mass driver at the destination.
Of course you would have to trust your engineers a *great* deal. One mistake and you could find yourself even slightly off target and on course for the side of a mountain. it's possible that a system like this might include some emergency system in the craft with a small stock of propellant for correcting their course if they're slightly off target. Or it might be used for cargo but not humans.
Depending on the distance you might need to accelerate your cargo up to something a little under escape velocity like 2 km per second.
Healthy Humans lying flat can withstand something like 10g for a few seconds. To accelerate up to close to 2 km per second at 10g, that means your mass drivers would need to be a few km long at either end.
Think of it as a little like a maglev train only without any tracks for most of the journey and with hellish acceleration at the start and end of the journey for about 20 seconds.
[Answer]
If you are looking for a means of transportation inside the domes, then bicycles is the right call. If trains are already overlooked, bikes then are nearly completely neglected. They are relatively cheap to produce and basically don't need infrastructure. They also don't need energy to operate and if the dome is only 1 km in diameter then everything is really close. The reduction of friction also helps, and the people are kind of forced to exercise, what is good in space, people in low G really need to exercise. They are also really small, something good in the crowded place that the people live.
I remember reading somewhere that bikes are being used in those big airports here on earth because of those features, and that they are a really smart way of moving if we ever go to space, but I could not find that report (maybe it was a video, possibly vsause or something like that) anywhere, sorry for that, if anyone finds that out, please show me, it makes a long time I've seen it.
The biggest problem with trains is the cost to make the rails and the amount of metal you have to put on them, something that is still not a lot compared with other means of transportation. If you need to have these big resources coming and going, the trains are the best option indeed, but if what you look for is people's mobility, bikes are just fine.
The thing with using bikes to dome-to-dome transportation is how far would you have to travel and the fact that you would need to make highway-like bike path. But since you only have 20 domes 2 miles apart each, if you put the in line and run through end to end, you would have to go through 82 km (38 miles = 62km, plus the distance inside the domes), a lot but still possible. If you were not to put them in a line but instead in any other shape (two lines, three lines, triangles, hexagons, ...) the maximum distance you would have to travel would decrease a lot, although you would have to build more roads. You can find the mid term that is best for you.
[Answer]
Other answers have very nice ideas, I just want to point out a few things that may not be obvious (and a quick perusal of previous answers didn't show them up).
* Low gravity means low friction, a "conventional" train wouldn't work because mass (and thus inertia) is still there, but friction is proportional to weight, and thus would be very much reduced; wheels would skid without transmitting much impulse to the convoy. Some linear motor, maglev or double-wheel with compression would be necessary.
* Same applies to curves in any direction, you need the same centripetal force, but using steering wheels simply wouldn't work.
* The same applies also to passengers; being less anchored to ground they would feel any speed variation much more.
* In this condition i think (relatively) small bubbles suspended to cables (or, better, to a suspended rail) are the best solution as they would swing freely and thus the resulting force would always be toward the floor.
* Stairs are something quite dangerous and should be avoided at all costs; even in Earth gravity trying to run down a ramp can have "interesting effects"; on the Moon it would be very easy to run straight into thin air following a parabolic trajectory which is guaranteed to intercept with the stairs (if they are straight), but possibly many meters down.
* Similar effects are expected for any vertical change of direction, all effects of any bump on the way are going to be greatly amplified, so special care to avoid them should be taken.
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**Giant ramps/chutes.**
I would have ramps going from the top/sides of domes to the base/recieving station at the other domes.
It's low tech, but it has several advantages. It isolates all the moving parts/intelligence in sending dome, with nothing to break down on route. These ramps can easily go over craters/etc, and ignore the geography below. Received objects (at least if not alive) can be queued at the recieving dome, and automatically will move to the next unload spot.
The lower gravity helps make it more practical than on earth. Its easier to built a strong ramp since there are fewer forces. It's going to take less energy to bring the "to be sent" objects up to the top of the chute. And earth doesn't have a lot of places that a 2mi jump to the next waypoint makes sense.
The chutes don't even have to be built that tall -- if you expect to send wheeled vehicles down the chute, it would need to drop 1m for every 500m of travel to move just with gravity. If you slide things down a teflon coated chute, it needs to drop 20m for every 500m of travel. Both of these are easily achievable.
Since gravity is overcoming friction already, you can add a nice impulse at the beginning to quickly move objects.
The chutes can be open (airless, less friction, probably automatic sterilization) or closed (allows transport of air, airlock free)
As a bonus, they can shaped like Futurama tubes (with Teflon coatings) and the descent shouldn't be noticeable.
To connect even more domes, you could have chutes that start in dome A went by dome B (and could have things snagged from it/added to it) and then continue to dome C, etc. That could be stretched as far as you want as long as it drops as specified above.
Or just build the 380 ramps to have a direct dome to dome ramp for each pair.
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So, as I've mentioned in previous questions, I am writing a series in which the four young main characters encounter natural, traversable wormholes that connect the present time to another one. I've vaguely figured how I want them to work and how this way connects (mostly) to the real theoretical science behind it (specifics will be explained below for those curious and if it connects to my question). My question now is this; If I want to continue being vaguely scientifically accurate, how would a speculative wormhole look to humans looking at it from outside? For someone stepping through it to the other side? How many artistic liberties can I really take while still being scientifically accurate? Thanks so much for taking the time to speculatively answer this question and have a good day!
(For those interested, the wormholes tend to stick near objects with larger gravity to keep our intrepid little explorers from stepping through one and ending up somewhere out in space and suffocating. They tend to occur most on the time equivalent of "fault lines" where time 'tears' more easily, like weak points on a blanket. Yes, I do know it's definitely more complicated than that, but I'm simplifying things a bit so it makes more sense. They also can connect places in both place and time, so they can end up from a little town in modern day Oklahoma to the volcanic jungles of Early Cretaceous China. Finally, they are also traversable by simply stepping through since the main characters are just a few teenagers who stumble across them and don't exactly have resources to get a vessel to take them through Interestellar style.)
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What you most likely want is an [Ellis wormhole](https://en.wikipedia.org/wiki/Ellis_wormhole). The picture in A. Forty's answer most likely shows exactly that; and as others have mentioned, Interstellar is about as good a visualization a wormhole as you're going to get from Hollywood. However, I don't think Interstellar got all the details right.
From the outside, the wormhole would look very much like A. Forty's image. Moving through the wormhole, the image of the other side of the hole would appear to expand around you, swallowing you up, and then you're on the other side.
If you were to look left or right (or up or down, for that matter) while in the middle of the wormhole, you would see the back of your own head. The hole has no walls; each side just wraps around to the opposite side. I believe Interstellar goofed on this one.
Shown here is what an Ellis wormhole in a 2-dimensional universe might look like from the outside:
[](https://i.stack.imgur.com/wlb7K.png)
Interstellar showed something like what you would see if you piloted a spaceship along this surface and through the hole in the middle, from one side to the other. However, in reality, the wormhole would be three-dimensional. You'd never actually see anything even remotely resembling the above surface- because we're *inside* it.
Imagine taking a 2-dimensional spaceship and sliding it around on that surface. Try to visualize what the ship's pilot would see, looking at the wormhole. Near the hole, his lines of sight would be bent toward it, so objects behind the hole would appear distorted and stretched out at the edges of the hole. Closer to the hole, rays of light could wrap around the hole multiple times before coming back out without going through, so the pilot would see all 360° of his surroundings (including the front of his own ship) reflected back and forth, squeezed into tighter and tighter rings.
Just inside that, an infinitesimally thin black ring coinciding with the black ring in the image, where light (and anything else) can zip around and around forever.
And inside that, he'd see into the world on the other side of the wormhole.
In the center of the wormhole, his line of sight would fold back around, like the black line on the right-hand side of the image. Off-center, the space would bend the pilot's line of sight at a much larger angle, so he'd get a (very distorted) 360° view of the other universe. The effect would closely resemble an image taken with a strong fish-eye lens, like the ones used in those 360° cameras. As before, all of those 360° would be repeated over and over, compressed into tighter and tighter rings approaching the black ring representing the halfway point.
Now compare all that to A. Forty's image.
Now, imagine that the pilot takes his ship through the wormhole. What does he see?
Well, first thing, as he approached, the fish-eye view of the other side would start occupying more and more of his field of view, as would the distorted space around the hole. Upon reaching the halfway point, light emitted from the left side of the ship would circle around the hole to the ship's right side. So by looking out either window, he's just see the outside of the ship from the opposite side. The black ring is now whatever color his ship is. Watching out the back window while exiting the hole would look much the same as going in did, except that the pilot's original universe now fills the fish-eye view in the center.
In three dimensions, the wormhole experience would be fairly similar, except the halfway point would be a spherical surface (which would appear as an infinitesimally thin black ring) around which light can orbit.
If these wormholes somehow exist in a gravitational field (because they're on Earth's surface, say), that should still work without any completely broken physics or anything. I'm not completely sure how it would work, but I have a guess.
Say the people on one side of one of these wormholes decide to build a bridge through it, so they can just walk through, from one side to the other, without having to jump through it or anything, because that sounds hard. This should be doable; there might even be normal gravity all the way through. If you were to fall off the bridge inside the wormhole, you'd just drop out of the hole on one side or the other. If you fell off the exact center of the bridge, you might wind up in a sort of gravitational saddle point. You'd feel as if you were being stretched in one direction (along the X axis, call it, toward the mouths of the wormhole), but gently compressed in the other two (Y and Z). You could float there as long as you were perfectly balanced in the X direction, but just a little bit off and you'd fall straight out the bottom of one side of the wormhole.
And finally, as to what being in one of these wormholes might feel like. Note how, in the image above, all of the space in and around the hole is curved kind of like a saddle or a Pringles chip, so if you drew two intersecting "straight" lines on the surface, they could curve in opposite directions. For instance, the two black lines shown. The center ring curves toward the hole in the center, while the line on the right curves away. This means the space has negative [Gaussian curvature](https://en.wikipedia.org/wiki/Gaussian_curvature). A funny thing about negative-curvature surfaces is that there is less space inside any shape drawn on the surface than you'd expect, based on its perimeter. This will do... weird things... to anything put into the wormhole.
Imagine you're sliding a small square of paper around on the surface shown above. If you try to slide it to the hole, you'll find that it won't stay flat on the surface. Either the center of the paper will pop up above the surface, or it'll just kind of crinkle. If you wanted it to lay flat, you could cut a notch from the edge of the square to the center, so it could spread out a bit and sit flatter on the surface.
Now... what would you happen if you put your hand into one of these wormholes? Quite suddenly, there would no longer be enough space inside your hand for all the bone and muscle and such that is there. Your skin would suddenly feel very tight, and some of the blood in your hand would be squeezed back into your arm. The bones in your fingers and hand probably wouldn't take kindly to being distorted in this manner, either. Like the piece of paper, they might just crack.
Best make these wormholes quite large, so these effects aren't strong enough to cause harm to something the size of a human.
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Wormholes can be manifested similarly to black-holes, but I think this image sums up what a transversable wormhole would look like under your criteria:
[](https://upload.wikimedia.org/wikipedia/commons/4/45/Wurmloch.jpg)
The light would also probably be redshifted a small bit, but this simulation is appealing enough.
Furthermore, you're asking how it would look to step through it. Depending on a few factors, I'd say Interstellar is a good source. A short burst of warped space-time and light, then you're out the other side.
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Wormholes are purely hypothetical, but would probably appear similar to a black hole. Take a look at the artistic interpretation of a black hole, from the movie Interstellar [here](http://interstellarfilm.wikia.com/wiki/Gargantua), and that of a wormhole [here](https://en.wikipedia.org/wiki/Wormhole).
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It seems to me that a photograph of a *non-lethal* wormhole will look exactly like two photographs, one on top of the other. The one on top will have a circular hole in it. The two should be the same scale, that is no magnification, nor should their be any distortion.
Why? Because if the light is being distorted, then there would have to be tremendous gravitational tidal forces involved, which would do bad things to matter, specifically to living matter. You could surround each hole with some sort of "leakage" - maybe a glow, or sparks, or some mild sort of distortion (like mirages - you know - *wavering*).
And of course while the hole would look circular, as you changed your position, the view would change as well. As you moved around the hole, the view through the hole would rotate as well. So, it would basically be a spherical TV screen. In fact, we could probably make one today that came pretty close (some TVs have horizontal curvature so you could make a ring out of a bunch of them.
Two problems with that:
1. The screen is concave, and you want convex
2. Screens available today don't have both horizontal and vertical curvature (as far as I know)
But anyway, a polygon with enough faces is very close to looking like a sphere, so just picture a ball with monitors stuck to it. Reduce it to the size you want your hole to be (4 ft radius?) and imagine the cameras showing the entire 4π steradians of from the (multiple) cameras viewpoint.
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if you've seen the film interstellar, it gives a pretty accurate representation of a wormhole
the argument goes something like this:
in 2-D models of wormholes, you have a bit of paper (our universe), you drill two hole in it with paper, then fold the paper to make the holes line up - wormhole
but a 2 d hole in 3 d becomes a sphere - which is what a wormhole would probably look like
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My postulations:
1. What the wormhole looks like depends on how light interacts with it/ passes through it.
2. If matter can pass through it trivially (i.e. simply stepping through with no ill-effect), light should act in very much the same way.
3. As mentioned by others, a wormhole is simply a 3D hole (most likely spherical).
In this case, I would imagine that the "look" of a wormhole will be surprisingly simple - in fact you would not see it at all! All you would see is a circular view of the destination the wormhole connects to, with no distortion, refraction (disregarding differences in air pressure on either side), etc. It would actually look a lot like an open door, except without a door or a frame.
The peculiarity would only show when you tried to walk around it - the hole will remain a perfect circle no matter how you tried to walk around it, and what you saw in it would be a 360-degree view of what was on the other side. Imagine if you had a wormhole from your current location to the inside of a museum, for instance - by just walking around the wormhole you would be able to see the entirety of the museum's displays.
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In one of the stories I'm writing, I have a character that falls from our world into another, far less advanced one, and brings his smartphone with him (along with a few other things, but they aren't important). Now, due to a magical artifact he finds in the region he ends up in, his smartphone is constantly charged, and has an internet connection through which he can view a static image of everything available on the internet at the time he left (no posting on forums or watching livestreams, but reading old blog posts/info sites/SE questions and watching videos that aren't live still works).
Now, the battery I can explain away fairly easily with magic involved, but the DNS system and others that make up internet connections aren't as simple (there's a reason it's called a net, after all). I could just say, "It's magic," and leave it at that, but I'm not the kind of writer to toss out internal consistency; and, frankly, the restrictions inherent in a logical explanation will most likely make for interesting plot points. So, without unduly stretching suspension of disbelief, what is the most logical way that magic could get around the handshaking and delays inherent in the internet system, and provide a static representation of the internet at a single point in time that is otherwise indistinguishable from how our internet appears here?
EDIT Section! Yay! There are a few things I need to clarify here, so I'll make a list:
* The MC isn't Batman-level prepared; he's just a prospective author who likes researching his stories. That makes the magically-boosted cache answer more plausible, but still tricky to pull off. Also, as a semi-techy person myself, code is hard. Just tossing in that "one super-techy friend" would strain the boundaries of plausibility, even if only for me, and when the author doesn't believe in their own story there's a problem.
* He wasn't summoned back by a spell or anything; his arrival was entirely unplanned. The general background plot I'm working with is that the ever-branching, butterfly-effect tree of chaos theory is an actual tree, and every once in a blue moon or five, someone falls down the branches.
* The world he ends up in is mostly non-magical; except for a little divine tomfoolery, there are no spells or enchantments to work with. The artifact he finds, however, is an example of said divine tomfoolery, but I still want it to be internally consistent.
* The idea of "Help, I'm trapped in a parallel universe" is fine and all, and I'll keep the idea in mind for later stories, but it simply won't work here; the plot of the story is much longer-term than that idea would allow. Also, the parallel-ness of the universe is slightly questionable; it diverged from ours a lot further back than most parallel universes.
Thanks for all the answers so far, though. I'll refrain from accepting an answer yet; the situation I'm working with is a lot more specific than my original question stated, and I don't want to accept an answer that fits my scenario over a better answer that's slightly too far from what I'm doing (but might work for others).
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How about this:
The magical artifact he found is one that was created by a god ("divine tomfoolery" and all that) who values knowledge and embodies curiosity. That god, absolutely horrified by a book-burning cult, created this artifact with the purpose of protecting any repository of knowledge (he meant mostly books, but wanted to keep the wording open-ended in case the people of his world might invent other methods of storing knowledge) from becoming unuseable.
So when this semi-sentient divine artifact sensed the smartphone within its mystical range, it identified it as an interface to a HUGE repository of knowledge - and noticed that its useability was threatened by the rapidly closing dimensional hole, which would cut off wireless internet access in mere seconds! Working quickly, the artifact downloaded all the sweet, valuable knowledge into itself, magicked the battery (which would've threatened the useability of the knowledge repository in mere hours otherwise!) to last indefinitely, and is now constantly listening for requests to access the knowledge normally available to this fantastic device, ready to answer as the smartphone expects so it will remain useable as per the artifact's divine imperative.
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**MAGIC COMBINED WITH NEXT-LEVEL TECH**
It's time-based magic, pure and simple. It's not that it's kept charged by magic, it's that it's stuck in a few minutes of time, so the battery never runs out and it can still connect to the internet, as it was. But I would add something to make it plausible. NEW TECH.
The problem is that phones today don't store the internet. If so, what the heck is it connecting to? Enter the Ghost Drive. That's just a name I came up with that I would use to handwave it all over the place.
What I would do is this--combine new tech with it. A friend has been fiddling with his/her phone and they are super techy. They're into some next level stuff. They've been messing with your main character's phone and computer because they simply can't resist. The MC doesn't understand what's been done, but somehow, the combination of this new chip or software and this magic has produced this result. Basically, they don't have to be prepared, they just have to have a reason to be carrying an experimental phone that does things a little differently. Reasons can include: they've been paid to beta test this new tech, a relative works at the company and gave it to them, or the aforementioned tech friend has messed with their phone.
Have a little fun. Make it buggy. There should be problems with it even before they fall in the hole. If your character isn't techy, they can hang a lampshade on it because they don't understand why it works either.
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I would say casting a wisdom buff on the phone could result it caching the best source of information available to that device quite similar to the effect it would have on a human. This effect would be the cache of google. When you perform a search on google, you could see text and images on a webpage from the google's internal cache. Obviously if you are checking cached page, you will not be able to interact with the website but the links are still navigable within the cache and it won't be updated. Similarly, this magic boosts the storage of the device and modifies it so that it would retrieve cached copies of websites.
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You might get away with a fairly large section of the internet, not the whole thing, by combining a couple things. I liked Diego Sanchez's comment about a phone with a really big cache, but if you're pulling magic into it anyway, maybe you can remove the question of "who put [the internet] there"
So, what the magic device actually is supposed to do, in this theory, is massively improve someone's memory (and sorta handwave support the secondary processes this improvement will need). It gets used on the phone, and the phone suddenly has a *great* memory - an *unnaturally* great memory, which manifests in the form of an infinite endless cache, of everything the phone has ever seen... including recovered, previously deleted information. Sure, the phone doesn't usually store that information for very long if at all - but if this is the equivalent of giving a person a photographic memory (that would let someone remember things they didn't even notice at the time and therefore *really* should have forgotten), then anything the phone *ever* loaded, or pre-loaded, might be fair game. So the phone doesn't actually have to have an internet connection, it just lets your person travel pages it already 'knows'.
The ever-full battery, is therefore not a primary happening, but the actual implication of the "sorta-handwaving equivalent of support" for the much-advanced memory. The brain takes up a lot of energy, suddenly improving its processing and memory will take up a lot of energy as well - so the device "handwaves" away the extra energy requirement by supplying the difference. In a small, simpler-than-a-human-brain phone, that's enough energy to keep the phone charged (though you could still have it get low on energy after continual use and need to recharge, just more like 'resting' than plugging in).
At this point, you have access to anything your person might have ever looked up - including all of their favorite sites, watched videos, and previous searches. You can broaden the base by having this person randomly browse sites when bored, do a lot of internet searches on random subjects - perhaps in service of a hobby, like SE, or the sometimes-strange questions that come up in conversations, or offer his phone to friends/family to look stuff up on (who might have any/all of the previous habits), if you want him to have access to pages he hasn't actually seen before.
You can end up with a good chunk available pages on his phone this way, especially if you add a couple things. Maybe the phone has a good buffer system (or whatever it's called), where it pre-loads all the links on a page being viewed, so that it loads faster if/when its user clicks them. Maybe the magic will let that go just a bit further, and load pages two links deep, or three. So viewing even a few pages with lots of links add a lot of previously unseen pages to the question, and a lot of pages have a few unrelated links, like ads or search engines. Very few trips to wikipedia would still net a pretty wide selection of articles, since they're pretty deeply interlinked. Having a website with lots of articles, or a search engine (like yahoo, google, whatever) as a homepage would give a really big cross section of internet-availability, even if your person rarely took time to read any of them.
So, instead of a "static view" of everything the internet had at one point in time, it would probably end up something more like a limited version of the internet archive wayback machine - multiple copies of some webpages, depending on when they were accessed, and gaps where other pages just hadn't been accessed and saved. The problem would be *finding* the pages, since search engines actually generate pages of results, which your person's phone doesn't have the framework to do... perhaps any "search engine" page will use a global search of the stored webpages instead, or even of the phone instead, or perhaps the search engine webpages will not work, but the phone internal search will have to substitute - then the trick will be to narrow results back down to something reasonable. Or perhaps the magic also enhances the phone's ability to figure out what your person is looking for, and generate searches and results that way, since the magic was supposed to enhance the mind and recall in the first place.
And this would take very little handwaving on the technical side, assuming a more or less normal phone. If you wanted to push the phone's capabilities a little, you could add Erin Thursby's suggestion of new phone tech, either a prototype or someone's experiment (or, really, just the latest release which is a bit further along in your person's world), to give the phone modestly greater abilities, which the magic will of course magnify all out of proportion. Maybe a bigger selection of pre-downloading pages, or a smarter user interface (like a siri or cortana or whatever, oh dear that might be explosive).
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I'd like to propose a slight modification of @Separatrix's answer:
The phone could be stuck in a time loop, endlessly repeating the period of a few minutes before it changed worlds.
-The battery discharges during the period of the loop, but then resets to it's starting charge once the period is over.
-The phone still has internet connection because it can talk to the DNS servers and the rest of the internet in the time while it was still in our world. Any messages sent, forum posts, etc. will get reset along with the rest of the phone once the loop period ends, giving an almost static image of the internet.
-The con is that for self-consistency the screen and the internal memory of the phone will have to reset at the end of each loop period too. MC won't be able to watch long youtube videos.
For style points, whatever is causing the time loop could only cover parts of the phone (leading to dead keys, malfunctioning microphone) or extend slightly beyond the phone (tingling sensation when touching the phone).
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Time and space are complicated, time is just a direction you can travel in.
He fell through a hole in space that no longer exists, but it did and he holds a link to that moment in time through his phone which is almost frozen in that moment. It holds the level of battery it had at that moment, it carries the signal it had at that moment and it still connects to the internet via that hole at that moment. The hole was there then, and he can connect via then.
It's not seeing an image of the internet, it is seeing the internet through a moment in time so always as it "was" at that time.
To allow it to actually load a page you can say that it's a constantly cycling second so it can make page requests and get responses. Perhaps his latency slowly increases the longer he stays as the signal has to travel further.
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I agree with the other posters: it needs to be live 2-way communication.
Make that part of your plot! His posts Help! I'm trapped in a parallel universe!” are taken to be trolls or unconventional fiction, and could even **be the vehicle for your story!**
You can have the novel be presented as a discussion thread where he posts his experiences, gets questions back from others, and explains more details. Repeat on different social media with varied reactions until he finally finds a board where it’s assumed to be fiction roleplaying and he gets useful feedback for his “story” that seems to the others to be a role playing game where they influence the main character.
Other threads on the board would be from people who are playing other scenereos and readers make comparisons and suggestions based on others. The main character puts up with it, supposing the *other* threads are fiction. Then he realizes that they are other people like himself! The few non-trivial highly imaginative never-break-character (and highly rated and followed) stories are in fact all *real* like himself. He’s not the only one to find himself in a different universe with his phone, and at least some survive and find this board.
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Why not just say that the Earth universe is a magical construct like it is in Discworld where the entire universe is a series of crystals/gems like in Men in Black each crystal being a static frame of the universe.
The phone then can use locater magic to see and locate thing in the crystal and the phone can decrypt the data in that frame that would be there. URL that is put in is simply an interface with this Locater magic. And obviously it only works for him because only his phone has the technology to decrypt the binary code that the locater magic reads and feeds the phone's internal circuitry.
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**Crystal “cellphone tower”**
There still is some hand-waving magic going on, but to a degree it works. One of the objects your main character comes across, builds or enchanted is a crystal that somehow queried the entire internet during its creation and saved a static image of it. Now their cell phone (while in signal range of the crystal tower) can communicate with it as though it had access to a cell tower. There are no other phones on the network so outgoing calls are useless, but there are lots of DNS address with fixed content waiting to be accessed.
How this crystal queried the entire internet is a little iffy. That’s got to be a powerful spell, or at least a very large crystal. Maybe it’s actually a full tower, not just a crystal sitting at the top of a tower.
A little world building, maybe it’s not a perfect copy of the main character’s worlds internet, maybe it’s a perfect copy of a universe very closely related to their universe. With there being infinite possible universes eventually you will have to settle for close enough.
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The static image of the entire Internet is harder to rationalise than full access. You can have some essentially magical explanation for access, such as a spirit of communication which can access the smartphone's homeworld now that it has something from there. Indeed, you have to have a magical explanation, unless you're going to start claiming that radio leaks between worlds, and that would have been noticed in studies of radio interference and the like. A spirit possessing a smartphone has lots of potential for mischief: the Discworld's Dis-Organisers, and David Wake's novel *I, Phone* are good sources of ideas.
But the static image of the internet requires, not just storing the entire current content, which is a ludicrously large amount of data, but also reproducing the on-the-fly generation of much of the content. For example, you mentioned being able to read Stack Exchange postings. There is no file stored on StackExchange servers that holds the version of this web page that you're currently reading. It was generated in response to your browser's request, and the only place it exists as a page is *in your browser*.
So full access is easier. There's no way your protagonist can get much help, anyway, unless you deliberately create similarities between the worlds for him to exploit. Claiming you've fallen into another world will just get you treated as a joker, or a nutter if you persist.
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I assume with static you mean you cant post or change things, but you will still get the latest info, like the mysterious disappearing of yourself in the local news.
A way to archive this: Your smartphone is no ordenary smartphone, it has special designed OS and automatically generate a VPN to your cooperation instead of your normal access to the internet, you access it through the cooperation firewall.
However your cooperation has the policy that posting is not allowed. Any HTTP request other then GET will be filtered. And maybe some other popular Sites.
While this would not completely prevent the ability to influence the internet, it could be enough for your story. You would still appear in the logs, everything that uses get to transmit data will work (unless the firewall has some special rules to prevent this, because it is a relay good firewall), but that doesn't mean your character knows this or find such services.
Some company also have the rules of no mails on holidays, which would prevent you from writing emails.
Maybe after some time someone will notice that your character access the network, and starts communicating with him. Or he will be trapped forever.
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I would like to point out that phones do cache web pages (proof, go to a web page, turn off internet, restart your phone, and open the browser again. page is still there. Refresh and it will fail). While only a tiny fraction of the internet, it is on his phone (though this is usually deleted once you close that tab, if there in no restore tab feature). And these would be snapshots of when he viewed them, not right now. (and time magic could give him access to any page he's ever been to, but still not the same as a snapshot)
Aside from that, you have the problem that he fell into another universe with his phone, but not the internet (which is a separate entity). So you now HAVE to explain why he has this snapshot of the internet. The only reasonable explanation is that, somehow, the phone is still linked to the universe it came from (a magic thread from what caused the transport, or some 'source id' property that allows tracing the tree back to the moment it fell in the new universe.) Since this artifact can magically interface with the phone somehow anyways, it might be possible for it to act as the phones 'router', tracing back to it's source time, and simulating the DNS resolution on that 'image' of his universe (or actually have a sister artifact there in a closed time loop of when the fall happened. Maybe responsible for the fall?).
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Exactly what could an obsidian blade do, if it were unbreakable?
Knapped obsidian holds an edge one molecule thick. It's sharp enough to cut between human cells, and is even used in surgeries today.
One of the conceits of this setting is that items of mythic power can only be broken or altered under specific circumstances. For all other practical purposes, a relic won't burn, shatter, warp, etc.
So an obsidian blade relic wouldn't be encountering issues of chipping or snapping off when directed at plate armor, stone doors, or the like. No, breaking the blade isn't an issue - though perhaps friction or binding would be. What other concerns and limitations would a wielder realize, with the use of such a blade? Would it get stuck in things, despite its unbreakable and peerlessly sharp edge?
Feel free to use hard science or common sense to describe answers. I've a basic understanding of tensile strength, shear strength, etc., but I'm looking for a way to describe this to readers in simple terms.
[Answer]
So you got an indestructible obsidian blade, now what?
It is ***not*** the ultimate weapon of all-cutting. While being useful against soft materials even in combat situations, harder materials might need more strength to achieve the same result in the same time. Ultimately you should be able to cut almost anything with it, but it will take time.
And yes, you still can get stuck. It will be easier to free than a steel blade, but ultimately an obsidian surface still experiences friction.
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## Usage as weapon
You will still have a hard time cutting any solid surface. For this matter, skin is not really solid\*.
To cut through for example a metal plate you have to first break the binding between the metal-atoms, which is pretty strong. Luckily your obsidian blade focuses all the strength you put in on a single-atom width line, so you can probably cut the first layer of atoms quite easily.
For the next layer you not only have to cut it, but also push the first layer a bit to the side, as blades are usually getting a bit wider away from the edge (otherwise you had a blade that would be only one atom in width). For every\*\* deeper layer you have to deform all the layers above.
This means you probably can not simply cut through the steel armor of your enemy, unless you hit him really hard. You may possibly not even cut his sword in half, though you could leave some nice cuts along the edge. It would be better for your enemy to replace the sword after the fight, but that isn't helpful to you *now*.
You're biggest problem is not that your sword might not be able to cut it, but that it might miss the cutting power. Weapons made from Iron do not only cut, they also crush due to their weight. So while an iron sword may not be able to cut through a particular leather-armor on first strike, due to the weight and the inertia it might still carry on where the obsidian blade due to it's smaller mass simply can't.
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## Can it get stuck?
Sure, put an anvil on it and it won't move an inch anymore. A blade can cut only at the edge, if something blocks the blade it is the same af if you put a sheet of metal (for example) between the two blocking objects. The only advantage you have over metal is that the surface of your obsidian can be much smoother, allowing you to pull it out easier thanks to a lower friction. But you still have friction, and you still have to overcome it.
## Can it get stuck when chopping wood?
Yes again. Penetrating the wood might be easy, but because it is wet the wood will expand slightly after cutting it, as there now is a gap of air. Then you have a whole tree pushing on your blade. You can likely pull it out in a second or two, but you should still pay attention when fighting (between) trees.
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# FAQ
## If I drop the blade (without the handle), will it drop to the core?
No, not likely. You still have to break apart the bonds in the material you want to cut, and the blade is not heavy enough for that. Also, the core is really dense, so it probably float on it's surface.
## If the blade could cut everything like hot butter, would it be the ultimate weapon?
Just because you can cut everything doesn't mean everything waits to be cut. Enemies may take you out from afar, or dodge your blow to land their own. Also cutting a tunnel through a mountain might be a bad idea, due to cave-ins. Last but not least, having a good blade doesn't make you a good blade-wielder.
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\* As we are talking about a 30 Angstrom blade and semi-free moving lipids, you shouldn't have a problem cutting through skin.
\*\* Technically once you made a cut deeper than your blade is high you don't have to completely account for the upper layers anymore.
[Answer]
Another answer has already given the basics:
* Piercing is only part of cutting
* The blade behind the edge is still subject to friction
There are a few additional points specific to blades made of real-life materials, however, that may be of value in thinking out what your superlative weapon can and cannot do.
# Terminology
To do this clearly, we need some basic terminology.
**Edge**: The edge is formed where the two bevels meet.
**Bevel**: The bevels are the flat parts that extend directly back from the edge at an angle.
**Centerline**: If you a draw a line from the edge to the spine, this forms a single line. The angle of a bevel is measured from the centerline with the vertex at the edge.
**Flat**: The portion of a blade that runs more or less parallel to the centerline, often incorrectly called a bevel (or, in reverse, bevels are mislabeled as flats).
Friction is an issue along the edge while dragging, and along the bevels and flats when deep into a cut.
# Teeth
All blades have teeth, like saws. These can be large or small, evenly or irregularly spaced, consistently or inconsistently sized. They can be perfectly in a line, splayed, or in multiple parallel lines.
When you try to cut something, you normally slide somewhat along the teeth. This is much the most efficient method. Each tooth penetrates in sequence, splitting the gap further open as you go along.
Because obsidian is volcanic glass, the teeth may or may not be parallel or in a line. Because the material has to be napped, the teeth will tend to be irregular in size, shape, and spacing.
This means that if the blade was originally just traditionally-napped obsidian your cuts will always be jagged. No matter what you do, your blade is always going to act like a serrated bread-knife or steak-knife.
# Shape (Profile)
With a real knife, if you had ultra-tough-and-hard materials, you'd polish the edge to bring all your teeth to a highly regular pattern of consistent size, but this blade can't be sharpened. And that's a problem.
If you have materials that just won't break, the obvious thing is to grind the bevels to as narrow a total included angle (the angle of both bevels added together) as you can manage, then refine and polish the teeth until they're super-small and perfectly even. This is how a razor is made, for instance. Normally, you don't do this with a weapon, because as soon as you hit something it'll crush, but that's not a problem here.
This pattern is ideal, because your knife won't wedge. That is, it has very narrow shoulders, because the bevels are extremely thin. When you cut, the friction of the cut material against the bevels is a significant part of what stops you from sliding through easily.
Unfortunately, you can't sharpen this thing. Since it's impossible to break, it's impossible to abrade. So you're stuck with whatever profile you started with.
# Cutting
Once you focus on the fact that your blade is always a saw, you'll realize that the usual smash-with-the-edge approach we associate with swords is grossly inefficient. The best thing is to drag the edge as you hit. So how well will your obsidian weapon cut?
The more regularly-spaced, narrow-beveled, and small the teeth--and the more they are all precisely in line along the centerline--the better it will cut.
If nothing can crack those teeth despite a gross lack of supporting material (very narrow bevels), then the thickness of the blade at the spine can be ridiculously thin. This will dramatically reduce friction. It will also make your blade weigh far less. Normally weight in swords is a serious problem, since steel is very heavy, but a very thin blade won't have this problem.
# Conclusions
You need first to decide what this thing looks like. Does it look like a thin, elegant sort of straight katana, but black as night? Or is it a massive, primitive chunk of death, with big irregular fangs? That will tell you what the tooth pattern should be.
Next, decide how heavy it is. Obsidian's volumetric mass is about 1/3 that of steel, for comparison. Bear in mind, if you make comparisons to extant swords, that many swords are not solid steel precisely because it's so darn heavy (katana are the most obvious example here). From a rough weight--say, that of a baseball bat?--you can work out the volume of the blade.
Once you know that, you can decide how thick you want the blade to be at the flat, and how wide you want it from edge to spine (or if it's two-edged, from edge to edge across the spine).
With all that in hand, you can work out quite easily how the thing is most efficiently used. Probably the best is going to be to hit somewhere around the lower third of the blade and then, while continuing to press as hard as possible, to drag the haft backwards. If the teeth are small and regular, it'll glide through anything; if they're large and irregular, it'll go clunk-clunk-clunk and make a nasty gash. If the bevels are narrow and the spine thin, it'll soon be a very, very deep cut; if wide and thick, not so much.
[Answer]
You said the blade cannot be broken or altered, but is that in the long-term or at any given instant? If the blade cannot be altered at all, ever, it has infinite hardness, which would cause a whole lot of physical issues on a whole lot of levels - for instance, since its molecules could not vibrate, it would be perpetually at absolute zero temperatures. It isn't really 'magically enhanced obsidian' at that point, but an adamantine-like material that is completely unlike anything that can exist according to physics.
Since this is presumably not what you are looking for, it seems that the most logical interpretation of 'unbreakable' is that relics *can* be deformed in the short term if a force is applied to them which would break or deform their natural materials, but if they are deformed, they immediately spring back into their original shape once pressure is released (presumably through magic). In other words, relics have effectively infinite *elasticity*, instead of hardness. This could also cause weird effects (for example, if you stretched it to the point where it became a line of single atoms several million miles long) but that would require forces not ordinarily encountered in a typical fantasy setting so would be less problematic than the 'infinite hardness' interpretation.
Such a relic, even if sharpened to a single molecule, would not really be an 'ultimate' weapon by any means. Obsidian blades are sharp, but brittle, and not particularly hard compared to most weapon and armor quality materials (which is why they can be knapped so well). Your blade would cut through flesh, cloth, leather, and soft plant matter like nobody's business, but trying to penetrate steel or any other material that would shatter or blunt an ordinary obsidian blade would be like hitting a stone wall with a Nerf foam sword - it might not break your weapon, but you clearly won't be getting anywhere.
An unbreakable obsidian knife would be useful for leatherworkers, surgeons, butchers, chefs, jungle explorers, hunters, theives, and backstabbing assassins. For fighting armed and armored opponents, you're better off going with conventional steel.
[Answer]
Considering that it can split cells and it sharp enough to cut through anything, it should never be able to get stuck. It should be able to move in a straight line wherever the blade it pointed, so long as the hilt can fit. It can't get stuck because it should be able to move back along the path it has already cut.
If only the cutting edge is that sharp, then it reverts back to the basic physics of normal swords, with the special property that it can easily create the first pierce of any material. This does give it better cutting and slashing powers, but it doesn't help the sept cut through stone unless enough force is applied to create a cut wide enough for the rest of the blade.
For basic application, it just becomes a super weapon and possible a very useful tool for crafting. You can cut anything to shape and, potentially, make items extremely flat.
This is just a rough presentation of my thoughts. If you could clarify if the entire blade is only 1 molecule thick or otherwise, I'll come back and make some edits
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[Question]
[
I have, what I hope to be, a fairly simple question. I am designing a planet where there are no carnivores.
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## Assumptions
1. The creatures would all be very complacent and would feed and live in very vulnerable positions, because they have never learned otherwise.
2. The creatures would mostly be brightly colored, because the pressure to attract a mate would be much stronger than the pressures to stay hidden.
3. For the same reason as the above point, mating rituals would become very elaborate.
4. Finally, the point I am most unsure of: The creatures would quickly acclimate to a newcomer to their area.
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## What I am looking for in an answer
1. Are my assumptions correct?
2. What would the impact be on the local plant life (assume earth flora). Could it sustain itself?
3. Could the population be controlled without predators to keep them in check?
[Answer]
The assumptions are reasonable, but I might change a few
>
> 1. The creatures would all be very complacent and would feed and live
> in very vulnerable positions, because they have never learned
> otherwise.
>
>
>
They would not feed and live in very vulnerable positions. Rather the definition of vulnerable shifts with the environment. Think about how you left your house this morning. Let's say you left out the front door. Did you open it a crack and take a sniff to make sure there were no predators nearby? Did you listen to the birds chirping to make sure it was safe before turning your back on the world to lock the deadbolt? Were you vulnerable? No. You were balanced within your environment. These animals will be balanced within theirs. It may look to us as though they are vulnerable, but in fact they are plenty safe.
However, complacency will never be seen. There is still going to be competition for resources, and it will be aggressive! Nobody's going to be sleeping on the job on this planet!
>
> 2. The creatures would mostly be brightly colored, because the pressure to attract a mate would be much stronger than the pressures
> to stay hidden.
>
>
>
I think its unclear whether bright colors would be used to attract a mate. Generally speaking, getting a mate to see you is easy. The bright colors are to impress. But why is it impressive? That's harder to say. Its entirely possible the lack of predators may make colors less interesting. With no reason to *not* be bright and flashy, its not exactly a good tool for judging the fitness of a mate. They may have to find more subtle ways to pick mates.
That's not to say the planet couldn't have bright and flashy animals trying to attract mates, just that it's not a foregone conclusion that they *must* be that way.
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> 4. And finally, the point I am most unsure of. The creatures would quickly acclimate to a newcomer to their area.
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What does it mean to acclimate? If I had no predators, and the only thing limiting my ability to live and reproduce is finite resources, I'd acclimate to their presence real quickly: I'd be guarding those resources with all my might. Just because we don't have predators doesn't mean the plants aren't going to develop herbicides to kill off competition, and the herbivores wont aggressively defend their turf. Death is part of the circle of life. Getting rid of predators wont change that.
>
> Could the population be controlled without predators to keep them in
> check?
>
>
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Predators are just one tool evolution has unearthed that limits a population. Fundamentally, its the quest for finite resources which really generates the limits. The competition for resources will be fierce on this planet, and many will die simply because they cannot find the resources they need to continue living.
Two fun case studies. Yeast is a magical compound. Not only does it make beer work, but it has a terribly interesting lifecycle. When yeast enters a fertile area, it multiples like mad in a haploid state which reproduces asexually. This is an extremely fast way to consume the newly found resources. Eventually, the haploids start to starve themselves for resources. With a quorum sensing like behavior, they undergo a transition, combining two haploids into one diploid cell. Once in this form, they undergo sexual reproduction. If the resources continue to dwindle, these diploid cells can form spores, which are hardened against the environment, ready to be transplanted into a more suitable location.
The other case study, Desulforudis audaxviator, is a fascinating bacteria. It is found deep in cracks in goldmines in South Africa. It is known as a "single species ecosystem." Not only does it not have any predators, it indeed *is* the ecosystem. There is no DNA present in the mines besides that of D. audaxviator. The fact that it can exist in balance tells me that you can find a balance without predators.
*Random factoid: D. audaxviator is the only known nuclear powered organism on the planet. One of its several metabolic channels is specialized at using hydrogen peroxide generated by the decay of Uranium atoms nearby.*
I think the biggest challenge your ecosystem faces is *why* there are no predators. With all of the competition for resources, it would be *very* reasonable for animals to try to take each other's resources. It doesn't take long for that to turn into predatory behavior. You're going to need to come up with an interesting mechanic to ensure predators don't evolve on your planet.
[Answer]
An ecosystem containing herbivores only, appears stable but it is not. The evolutionary history of Earth proves that in the absence of carnivores/omnivores, some of the herbivores would evolve to utilize this free source of food. Examples include:
1- Dinosaurs. While the pioneering genera like Nyasasaurus were omnivores, they gradually split up into pure herbivores and pure carnivores.
2- In mammals, whales are closely related to hippopotamuses, which means they were herbivores. They later settles on shorelines and gradually shifted from herbivory to carnivory.
So no. In the long term (a few tens of millions of years), herbivores will shift on to carnivorous lifestyle if such creatures are not already present in the ecosystem.
[Answer]
The fauna in a world with no carnivores will not look like that of earth with the carnivores removed. Disease and both intra- and inter- specific aggression will likely be the major causes of mortality (popular science link re. disease: <http://www.bbc.co.uk/earth/story/20150327-ten-scary-diseases-of-animals>).
Predation pressure is a major factor driving the grouping behaviour of animals, so without predators, many species may never evolve group living (whether that be organised sociality such as seen in many primates, for example, or the passive aggregations of savannah-dwelling herbivores.). Add to this the issues of disease - social transmission, decaying corpses of dead members of multiple species - and the likely outcome will be small groups or solitary individuals, possibly highly mobile (to avoid the rotting bodies).
If the rotting corpse issue is explained away (perhaps the abundance of this resource has selected for bacteria that decompose corpses on an accelerated time scale), then the biology and behaviour of the herbivores will be shaped largely by whether their resources are defensible. Population sizes are likely to be large - given no predation - so territoriality will not be feasible as time/energy costs will be too high. Instead, individual resource patches would be defended, and this will favour large groups, which in turn require access to multiple resource patches to meet their collective nutritional needs.
So intense inter-group competition, selecting for large-bodied, aggressive, 'weaponed' animals.
With that in mind, and addressing the question:
>
> 1. Are my assumptions correct?
>
>
> The creatures would all be very complacent and would feed and live in very vulnerable positions, because they have never learned otherwise.
>
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Clearly not. In some if not many cases, the herbivores may look/behave much more like 'carnivores' (of Earth fauna). The nature of vulnerability will change (vulnerable to inter-group violence, rather than predation), but it will still impact behaviour.
>
> The creatures would mostly be brightly colored, because the pressure to attract a mate would be much stronger than the pressures to stay hidden.
> For the same reason as the above point, mating rituals would become very elaborate.
>
>
>
It would be easier for such mating rituals and colouration to evolve, given the absence of predators, but whether or not it does depends on intensity of mate competition, and the balance between inter- & intra- sexual selection.
>
> Finally, the point I am most unsure of: The creatures would quickly acclimate to a newcomer to their area.
>
>
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If the logic above is correct, then the opposite.
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> 2. What would the impact be on the local plant life (assume earth flora). Could it sustain itself?
> 3. Could the population be controlled without predators to keep them in check?
>
>
>
Simple answer, yes. Population numbers will adjust to the available resources through the mechanism of competition. Intense foraging pressure might lead to localised ecological changes - grass, for example, is much more resistant to consumption than arboreal leaves - and there may also be selective changes on the plants to resist high levels of consumption by high numbers of herbivores. So thornier, tougher, higher levels of tannins and other 'anti-feedants', which in turn will decrease available resources, and increase the intensity of the competition between the herbivores.
[Answer]
1. I agree with your first three assumptions, but I'm not so sure about your last one. It's really hard to tell unless we know whether this species is naturally aggressive or passive.
2. >
> Three factors can limit the speed of photosynthesis: light intensity,
> carbon dioxide concentration and temperature. Without enough light, a
> plant cannot photosynthesise very quickly, even if there is plenty of
> water and carbon dioxide. Increasing the light intensity will boost
> the speed of photosynthesis.
>
>
>
Basically, this quote is from [here](http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_21c/life_processes/plantfoodrev5.shtml) and it tells us the easiest way to speed up photosynthesis is to increase light intensity. So I suppose if the light intensity was high enough, the flora could photosynthesize faster. Also, if the plants had photosynthesis-speeding enzymes in their body, they could photosynthesize faster. Or perhaps the plants [chemosynthesize](https://en.wikipedia.org/wiki/Chemosynthesis), in which case none of the above is relevant. Either way, I think if you added one of the modifications I suggested, you should be fine.
3. Sure! You simply just have to create a natural system to keep the population in check. Perhaps, every four months or so, some sort of natural acid rain occurs. This could kill any organisms feeding off of the plants. If these organisms would've adapted to the acid rain, then simple overpopulation will kill them off. Without room to live and enough food to eat, some will starve to death, so in a way, nature controls the number of these organisms on the planet at one time.
[Answer]
That's exactly the situation in James P Hogan's [*Giants* series](https://en.m.wikipedia.org/wiki/Giants_series). Initial observations of drawings and other representation are taken (by us) to be cartoon characters and are presumed to be unrealistic.
As I recall, complex life (equivalent to our vertebrates) developed a secondary circulation system for carrying waste, and this developed into a toxic defense rendering all such life inedible.
(Yet there were canned fish noted in the original novel, so there's another story there.)
Now in this story, animals were also very vulnerable to their own toxicity, and even a minor cut would be fatal.
I note that just because animals can't eat each other, they can still kill each other in competition for resources or reproductive success! Look at lethal conflict within our own species: it's not due to predation. But people still must protect themselves.
You ask about plant life being able to sustain itself. Autotrophs are the base of the food chain now. Each generation of predation yields only 10% of the energy, so the amount of biomass enabled by predation is 10% of the 10% that are herbivores. IOW, not much of the total biomass.
This doesn't consider the decay processes, which might exist if predation does not. Likewise for disease and parasites. These might all have different considerations and ways around the blocks.
Look at the effects of the [carboniferous](https://en.m.wikipedia.org/wiki/Carboniferous) period, where for t0 million years after the appearance of "wood" nothing could eat it.
What if something similar happened to a major branch of animal life. Something essential that's part of every cell is indigestible and even toxic to all other life. That would mean that not only would animal cells not be etable but it could not decompose either. Actually wood decayed except for the particular lignin and suberin proteins which piled up.
If animals had something in their metabolism that could not be broken down, digestion would just work around it. If it were actually toxic, how could normal metabolism work? So maybe it's just toxic if existing enzymes try to break it down, so early filter feeders simply rejected the cells that contained it and never learned to digest "meat" so that never emerged. Decay processes manage to separate it out so leave that protein behind.
A complex organism could exist like the way a cow eats grass. But it's contrary to such a design to have it run down prey, and it doesn't get the benefit of fast energy anyway: it might be less efficient than eating plants.
[Answer]
To answer question #3:
And also answering, “How could this scenario exist?” could be: an intelligent species on the planet kills any being that eats other than light or plant life, in order to feed, or anything like a cookoo bee. So the evolutionary tree is tended like a shrub or bonsai.
[Answer]
>
> What would the impact be on the local plant life (assume earth flora).
> Could it sustain itself?
>
>
>
If animal food is not plant also. The animal feed itself by Photo-synthesis (like plant). Therefore, not much impact on local plant live and animal can sustain itself. ( `[Starcraft Protoss][1]` can photo-synthesis so they don't need food)
>
> Could the population be controlled without predators to keep them in
> check?
>
>
>
WAR. They killed each other so we don't need predator. You can create the scenarios where WAR is a MUCH.
For example:
Honor: war is good for both side because who die in battle will live in honor with their god (?!)
Mating: their is unbalance sex (male or female) so the others have to fight for it.
(read more about the Pig in [Speaker of the Dead](https://en.wikipedia.org/wiki/Speaker_for_the_Dead) for some idea)
Spoiler: After die (life 2), pig become tree (life 3). Who die honor (being plant) will become Father Tree, which can mate.
Question about the pig:
[Does “planting” have any biological impact on the Pequeninos (piggies)
lifecycle?](https://scifi.stackexchange.com/questions/110188/does-planting-have-any-biological-impact-on-the-pequeninos-piggies-lifecycle)
[Answer]
Controlling population of animal life on a plant with no predators could be achieved if all the females had long gestation periods and/or only 1 offspring per litter, or if females only produced a few eggs per lifetime, or if females where only receptive 1 day per year - many variations are possible to create a viable world without predators.
Dead animals add nutrients back to the soil so more plants can grow and produce fruits, beans, nuts, vegetables etc... result.
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[Question]
[
A pretty major component of a lot of anime shows and other media is oversized weapons, like giant swords, hammers, the like. These types of weapons would be completely unfeasible in the real world, but it got me thinking of ways to make them easier to handle and use.
If you were able to negate the effects of gravity on a giant sword how would it handle? My assumption is it would be like handling it in micro-gravity, as in, it would be a similar situation if you took it up to the ISS and tried to swing it around, which may make you able to lift it and move it around, but it would still be ineffective as a weapon, is this assumption correct?
For the purposes of the question, assume the sword is 7 feet long and a foot wide. (Much like Cloud's buster sword from Final Fantasy VII)
If this is the case the real question becomes: What would be the best type of weapon to use if you could negate the gravity affecting the weapon.
[Answer]
Fantasy is fantasy, not realistic at all. Oversize swords are worse than a Klingon Bat'leth since you might be able to at least defend yourself with a Bat'leth.
The purpose of a weapon is to discourage, disable, or destroy. Attempting to wield a 7 foot steel blade with no weight, but 20 times the normal inertia is still a very, very bad idea. A swordsman using a standard long sword weighing 3.5 pounds (a little on the heavy side actually) will easily defeat you. Force = mass x acceleration. If you are wielding some with 20 times the mass (and 40 times the rotational inertia) you will always be way too slow as you struggle to move your sword around. A common sledgehammer is around 10 pounds, try swinging one of those around quickly and you will find it impossible. This is not because of its weight, but its inertial.
You want to be able to accelerate your weapon at about 10 gees. The weight of the sword is thus only about 10% of the resistance due to inertia. Found an article subtitled [Observations on the force exerted by a sword in swing](https://prezi.com/owybr_qzhd6b/sword-swing/) that mentions: `On average the test swords swung with 10.54m/s velocity and 117.19m/s^2 acceleration;` (11.95 gees) -- so a little higher than my memory, but the testing conditions appear a bit artificial so maybe 10 gees is a better number anyway.
Unless you can get inertial compensators, lose the over-sized blade and get something that will actually be much more effective as a weapon. Now, suppose you are super strong, 20 times human strength. You still don't want that oversize weapon, you don't need to cleave an armored man in two to be effective. Imagine what Hercules could do with a standard longsword. Perhaps a two-handed greatsword would be better for Hercules because of the greater reach. But a 70 pound sword would just make Hercules slower than necessary. Due to great strength and skill Hercules might well find a heavier weapon more optimal than that a normal man might choose, but since Hercules would still favor speed over overkill power, the heaviest weapon that preserves most of his speed is still his best choice. With his great strength any contact would be likely to kill or seriously wound any opponent.
Best weapon type depends upon type of combat. Mounted combat? Armored? Man on Man vs. Army vs. Army. One foe vs. multiple foes. No single weapon is ideal for all forms of combat or combat styles. If I had to select weapon without knowing combat type, I would probably select based on what works with my preferred combat style and experience and hope for the best.
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Would anti-gravity help? A little - you don't have to lift the sword using your muscles so you would tire at a lower rate. How does antigravity work. Does it just means that Earth gravity is cancelled or does it cancel gravity from the sun, the rest of the galaxy, etc. Since these accelerations are multiple orders of magnitude less than 1 gee, you can ignore their effect and in fact do so every day.
How would an inertial compensator work. If it just cancels all or most of the inertia, your big sword now hits like a small sword because it has also lost momentum and kinetic energy. Thrusting attacks would still be mostly effective as they are less dependent on the inertial of the weapon. If your inertial compensator is smart enough to restore inertial just before impact or only compensate for inertial changes supplied via the hilt you would suddenly have a more effective weapon.
Adjustable inertial compensation would actually be pretty useful as you could set the mass of the sword based on combat conditions, and the extra reach would often be useful. You would not want to eliminate mass entirely as this would create a weapon with very poor balance, i.e., contact will tend to wrest it out of your hand.
Given the high tech levels required, one has to wonder why you would want to use a sword though. The only thing I could thing of beyond personal ego or fantasy role-playing was to assume you might be able to sneak in the tech in a setting similar to [Ranks of Bronze by David Drake](https://en.wikipedia.org/wiki/Ranks_of_Bronze), the sequel the Excalibur Alternative by David Weber shares the tech level limited fighting scenario and may give you some other ideas.
[Answer]
Historically overweight weapons were used for training. The purpose was to make your sword arm stronger and more resistant to fatigue. If your arm gets too tired to fight effectively while the fight is still on you generally die.
The downside is that since overweight weapons have more inertia you do not learn to use the normal weight weapons with the speed and precision they are capable of. Because of this overweight weapons are not really used any more I think. Unless you expect the students to face a chaotic life or death melee of unknown duration training with the actual weapons simply works better.
Historically such combat **was** expected and it was often too chaotic and exhausting to use any "fancy stuff" anyway. Or more precisely after the fight got started exhaustion and confusion would handicap you anyway so training with overweight weapons wasn't a real problem.
Additionally more technical the skill, more teaching time per student would be required. When training an army it is better to train them to have strength and endurance with basic skill than any real technique and finesse. The economics work better.
But that is all about training, what about actual use in combat? Well, some exceptionally strong individuals **did** use overweight weapons in combat. Although it has always been rare since, like Gary Walker pointed out, it does usually compromise your ability to defend your self with the weapon.
So the first criteria should be that you do not need the weapon for defense. Heavy armor and shield (for one handed weapon) should be required. For your scenario, if everyone else is using guns, defensive aspects of swordplay might be irrelevant.
Second criteria should be that you can choose when to fight and when not to, so that you do not suffer from fatigue caused by the extra mass. A leader with body guard to watch his back, a guerilla fighting fast hit-and-run actions and so on.
Third, you have trained with the overweight weapon a **lot** and have little experience with normal weight weapons. Typically, this would be someone who wants to be strong and because of that trained obsessively with heavy weapons to get stronger. Actually learning to fight should have been an afterthought at best.
Fourth, there should be an actual benefit from using the overweight weapon. Usually this would have been psychological. If **everybody** knows you fight with a weapon too heavy for others, the effect on morale can outweigh anything you actually do with the weapon. You might be so strong that relying on your strength to overwhelm your opponents might be a reasonable tactic. In such case using a really heavy weapon might make sense since it would allow applying more strength to beat the opponents defences. You might simply not be confident in using anything other than your training weapon.
**In conclusion:**
Negating gravity does not seem to be anywhere in the criteria for using overweight or oversized weapons. As others have mentioned it is generally the inertia that matters.
The kind of weapon would depend entirely on the reason an overweight weapon is used. A sword or axe of some sort is generally used for psychological effect. A staff or mace might work for applying strength. And of course, if the reason is because you do not know how to use anything else, that, whatever it is, is what you use.
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Gravity is not your only concern when wielding extra-large weapons. The inertia acts in all directions so that swinging that huge sword around would still be extremely difficult. Consider pushing a 20 kg weight laying on the ground to slide it on the floor. It's not easy, right? That's the case with ultra-large sized weapons too. Getting rid of weight of the object will **not** get rid of its inertia too.
That being answered, the best weapon in gravity-free environment would be a hammer. It is direct, simple and you don't cut yourself up if things go wrong swinging it. Just make sure the hammer head is at least 4 feet away from you. I suggest the hammer's head to be ~10 kg in weight.
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I'm aware this isn't really an answer to the question, but -
It seems like if most of the weight of the weapon (~90%) was fuel that fired a rocket, it could almost achieve what the user of your massive weapon wants - for very short durations.
The rocket would need to be multi-directional if you wanted to do anything more dextrous than chop wood. You'd want this to be handled automatically based on the user's thoughts or subtle hand movements ( like power steering ), as it would be pretty much impossible to handle a manual system of rocket adjustment with the speed required while fighting someone.
Assuming that all of that engineering is complete, the main limitation becomes the propellant and how long it will last, both during storage and active use. A weapon's worth of rocket fuel would probably have a burn duration well under a minute. Of course, if you're only fighting a single opponent, you should only have to hit them once!
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If a weapon negates gravity, then **any damage inured by it's weight is negated**. Weapons that don't slash or pierce would be far less useful unless you used some superhuman strength to swing them.
Should a weapon be weightless, then **a weapon that acts as an extension of your body would be ideal**. Preferably one that slashes or pierces. Blunt objects could work, but it would be better to simply use a buckler or something to defend yourself, after all, **if you can negate gravity then why not make a massive suit of armor that weighs nothing**?
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[Question]
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Could an artificial plant species be designed and created that lives in a vacuum - for example on the surface of our moon?
The main problems I can see immediately would be the lack of an atmosphere for respiration, the lack of microbes in the soil, and the massive temperature swings. Would it be possible to biologically engineer something able to survive and reproduce in those circumstances though?
[Answer]
There's [an Orion's Arm article](https://www.orionsarm.com/eg-article/5ac4f73ad5760) about this, which lists the various challenges faced by plants in vacuum and the ways in which these could hypothetically be solved. It's not exhaustive and I've added some of my own comments:
* Extreme temperatures, both hot and cold. These could be solved by variable albedo (the plant being able to change its reflectivity so it reflects more light during the day), high thermal mass (a bigger plant heats up and cools down more slowly), [geothermal heat exchange](https://en.wikipedia.org/wiki/Geothermal_heat_pump) (the aboveground parts of the plant are kept at constant temperature by circulating sap from the belowground parts, since temperature is more stable belowground) and freezing tolerance (the plant can survive freezing in the cold night and thaw out in the morning).
* Lack of liquid water; [water can't even exist as a liquid in a vacuum](https://en.wikipedia.org/wiki/Water#Triple_and_critical_points), but water is essential for plants. Water would need to be provided in vacuum-stable forms such as hydrated minerals ([some real-life plants can use water from minerals](https://www.nature.com/articles/ncomms5660)) or ice underneath an insulating layer of soil.
* No CO2 or O2 uptake from the atmosphere, since there isn't an atmosphere. Plants need CO2 for photosynthesis and [they also need O2 for respiration](https://www.gardeningknowhow.com/garden-how-to/info/can-plants-live-without-oxygen.htm). The Orion's Arm article doesn't give any solutions for this. Presumably, a plant in vacuum would need to somehow gain these substances from the soil it's grown in. Another implication of this is that plants would no longer need [stomata](https://en.wikipedia.org/wiki/Stoma), since stomata are used for exchanging gases with the atmosphere.
* No wind or animals to assist pollination and seed dispersal. Without these, plants would need to use [gaseous](https://en.wikipedia.org/wiki/Puffball) or [mechanical](https://en.wikipedia.org/wiki/Impatiens_glandulifera) methods to spread their pollen and seeds, or [reproduce vegetatively](https://en.wikipedia.org/wiki/Vegetative_reproduction) (e.g. by sending out runners).
* Elevated radiation, since there's no ozone layer to stop UV and no atmosphere or magnetosphere to stop particle radiation. The article doesn't really mention this, but a vacuum plant would need high [radioresistance](https://en.wikipedia.org/wiki/Radioresistance) in order to survive, grow and reproduce.
One thing to take away from this is that most of a vacuum plant's biomass will probably be underground, where it's relatively safe from these challenges. The only aboveground parts would be the leaves and possibly the reproductive organs.
[Answer]
Plants which perform photosynthesis [require carbon-dioxide to grow](https://www.youtube.com/watch?v=2KZb2_vcNTg). The metabolism of plants converts CO2 into carbon and oxygen through photosynthesis. The carbon is the main element a plant is made of. Without a carbon-dioxide atmosphere, a plant can not grow.
However, you might be able to grow **mushrooms** in vacuum. [Fungi](http://en.wikipedia.org/wiki/Fungus) don't perform photosynthesis. Instead they absorb organic compounds which are or were part of other plants or animals. That means they technically do not need an atmosphere. But you will have to provide a source of nutrients. Fortunately fungi are surprisingly versatile. According to Wikipedia:
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> Fungi have evolved a high degree of metabolic versatility that allows them to use a diverse range of organic substrates for growth, including simple compounds such as nitrate, ammonia, acetate, or ethanol.
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Many of these simple compounds have been detected in nebula, so finding a natural source of them in space isn't far-fetched.
I am not a biologist, but I doubt that you will find a fungi species on earth which grows well in vacuum because their cells evolved to be stable within 100 kPa atmospheric pressure. But you might be able to create one through genetic engineering or, when you have the time, artificial selection (create cultures, lower pressure until most of them die, wait until they regrow, lower pressure further).
[Answer]
**1.: You need water** - Fun fact. First "plants" on Earth started in atmosphere without any oxygen. But without water (Moon soil) you would be no go with even the most clever design ever.
**2.: You need minerals** - You can go away with microbes, but the plant needs to feed on something. That is how we grow most vegetables for mass production: Hydroponic planting in water enriched by all minerals what plant needs. So again, water only is not enough. Water with minerals could be a GO, but:
**3.: You need stable environment.** Although you could avoid a loads by clever DNA design of such plant, still, on Earth you have temperature range from -80 Celsius to +50 degree Celsius. I believe that on surface of Moon you can go more extreme ranges.
Long story short: It is engineering problem:
You need plant of a design which would keep its own micro-atmosphere (sphere like design, where plant would breathe inside such sphere)
You need a plant able to survive extreme temperatures both ways. Basically taiga wood mixed with desert cactus.
And, bonus, such plant should survive with as little water as possible (more cactus design than Siberian taiga wood)
In sci-fi setup of really developed DNA engineering, I think you could pass such idea on. But in reality I think you would crash on extreme setup of the environment.
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A plant like bamboo? Very unlikely, however, if we go small you might make it happen. [Lichen](http://en.wikipedia.org/wiki/Lichen) and moss might be able to be designed for such a thing. I know lichen isn't a 'plant' but algae will make chlorophyll.
Things that hug the ground would have a better chance of surviving, just look at would lichen can be found here on earth, they can live in some very inhospitable places. They might be able to hold a small atmosphere and break down the rocks and other minerals and it could handle going into stasis every time the moon turns away from the sun.
So I would expect we would start by playing with Lichen then maybe move on to mosses and go from there
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I would picture this "plant" as appearing as the trunk of a Baobab. Any branches would be very short and may not even exist. Its appearance may be more similar in shape to a saguaro cactus rather than a tree. Any leaves (needles?) would be more photo-voltaic solar cells rather than being chlorophyll-based. The interior of the (water-tight, air-tight, vacuum-proof) trunk would be stocked with water, minerals, and gases that the tree would consume to live and grow.
I would assume that the purpose of such a plant would be to use specialty roots to slowly process dirt and rocks into usable materials. Resupply runs would be needed to replenish its stockpiles and to harvest anything useful it produced.
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you could make the plant have some air scacs, which contain oxygen, for some aerobic respiration, and some CO2, as for photosynthesis, you could modify it so it needs the same amount of O2 as CO2 theese sacs could be either in all leaves, some specialized leaves, directly around the plant's trunk, or others, but the plant still needs some minerals, even if it could get them, like epiphates, from the air which has far less nutrients than the soil, there are no nutrients in a vacuum, but in the moon, i think you could find them (also the reusal of those nutrients is possible)
edit: please look at my comment, it gives good information too
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[Question]
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There is this setup that I've seen a few times of a ring-shaped world where people live on the inner side. My question is: what is the minimum advancement of technology for such a thing to happen?
So first:
* can it exist by itself without any crafting of any sort?
* if no, how close? is a ring shaped planet something ever heard of?
And then to live on it, I'm assuming that you'd need to:
* create / maintain an atmosphere (can it work without enclosing?)
* create / maintain gravity (what happens close to the edge?)
* ...other things that will come up...
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> My question is: what is the minimum advancement of technology for such
> a thing to happen?
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* **As long as it's not a ring around a star, you might be able to start with today's technology - if you don't mind it only being small** (a kilometer, or maybe a few Km) in diameter, and floating in Earth orbit. The hardest part might be getting it to be self-sustaining.
* **With somewhat later near-future tech, you might be able to build the same thing but larger**, like [Elysium](http://hdwallpapersmart.com/wp-content/uploads/2014/03/7OD3tYs.jpg), a [Stanford Torus](http://en.wikipedia.org/wiki/Stanford_torus)-like [space habitat](http://en.wikipedia.org/wiki/Space_habitat).
* **If you want a ring around an entire planet, you need much more material and technology to build it, keep it in place, and keep it from falling apart.** You might want to start with a planet that already has rings, or break the moon of an earth-like planet into pieces, since they are already about the right orbit, though even that is a ridiculously enormous engineering project, and one wonders why one would want to do this other than that it seems like a cool idea.
* **If you want a proper "ringworld" around a star, good luck.** That's absurdium-level technology, because not only do the materials need to be impossibly strong, but the amount of absurdly-strong material you need, is probably far more than the total material that even exists at that star, so you need FTL shipping capacity to import from other star systems light-years away. Though, if you already have the technology to have it hold together in the first place, maybe you can design something that will just capture solar wind and have it accumulate where you want it, so it just accretes in place from solar material... and somehow gets turned into impossibly strong stuff, though then you probably also need to be very patient for solar wind to amount to that much, though maybe you can divide that time down by somehow pulling most of the solar wind from all directions there, or even suck up some solar eruption material.
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> can it exist by itself without any crafting of any sort?
> if no, how close? it a ring shaped planet something heard of?
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No. Closest are planetary rings and asteroid belts.
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> And then to live on it, I'm assuming that you'd need to:
> create / maintain an atmosphere (can it work without enclosing?)
> create / maintain gravity (what happens close to the edge?)
> ...other things that will come up...
>
>
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The low-tech versions need enclosure.
Gravity you get artificially by rotation. Close to the edge, nothing. Over the edge, you fall off. But you need to keep the air in, so you probably have walls, cliffs, mountains, or whatever your atmosphere enclosure is on the sides.
For the vastly larger and higher-tech planet-encircling and star-encircling versions, you may as well say you have force fields that can keep the atmosphere there, if you have the other super-tech abilities. Or you could just enclose those too, assuming your impossibly-strong material has a transparent version.
Other things to consider are the energy required to keep everything in place, not falling apart, powered, heated, cooled, and repaired when things hit it.
Encircling a star of course has the night/day issue, but again, if you're able to actually build a star-circling world, no doubt you can arrange for whatever sort of sky display you want.
To me, the largest barrier to an actual star-scale ringworld is, if anyone ever had that much technology and resources, why would they ever choose to do that with it? It seems there would be far more efficient ways to use those god-like resources. I'd simply terraform existing lifeless planets and make them really nice and full of nice healthy lush environments where people and animals idyllically coexist, and I'd have done it thousands of years sooner than anyone could do a ringworld.
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**Orbital stability**:
Ringworlds are unstable. There is a net gravitational pull towards the near surface, meaning that a light source in the middle will eventually fall onto the ring (or, for something star-sized, the ring will fall into the star). You need an active stabilization system (magnetic manipulation, solar sails, attitude jets) to keep this from happening.
**Surface gravity**:
A non-spinning ringworld has a net gravitational pull towards the surface of the ring, but it's not very strong for anything a reasonable person would consider a "ring". In order for a practical civilization to live on the inside surface, you'll need to spin the ring at a pretty good speed to generate gravity through centrifugal force.
**Material strength**:
The material of the ring needs to be strong enough to hold itself together against the forces generated through spin gravity. Using the thin-wall formula for [hoop stress](https://en.wikipedia.org/wiki/Cylinder_stress#Hoop_stress) (a reasonable assumption for something people would call a "ring"), a whole lot of things cancel out, leaving
stress = density \* acceleration \* radius
`density` is the density of the material the ring is made out of, `acceleration` is the effective surface gravity due to spin, and `radius` is the radius of the ring. Here's the bad news: `radius` is huge. For a ring only a thousand kilometers in radius, you're looking at hoop stresses on the order of 10-100 gigapascals, requiring exotic materials such as carbon nanotubes to hold things together.
**Atmosphere containment**:
Your ringworld needs walls to keep the atmosphere from falling off the edges. The height of the atmosphere is described by a parameter called "[scale height](https://en.wikipedia.org/wiki/Scale_height)", which depends on the temperature and molecular composition of the atmosphere, and the effective surface gravity. As a rule of thumb, the walls should be at least ten scale heights tall; for an Earth-like environment, that's about 80 kilometers.
**Sediment handling**:
If you've got any sort of soil-like surface (as opposed to a purely rocky or technological surface), you need a way to counteract erosion. Water flow will tend to wash soil into the nearest body of water, and a ringworld doesn't have the geologic cycles to bring it back up through mountain-building.
**Conclusion**:
A natural inhabitable ringworld isn't going to form. Even ignoring that there are no known processes that can form one, the material strength and orbital instability issues will keep it from forming. A high-tech civilization can build one, but the larger it is, the higher the required technology level.
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Gravity, as far as I remember from what I've read on ring-worlds, should work through rotation - as the ring rotates around the star, the centrifugal motion keeps everything stuck to the inner surface. That means that if you walk off the edge, you probably are shot straight into space (might be convenient for spacecraft though). The effect would be pretty sharp too.
For the atmosphere to not evaporate completely, you'd need gravity and enough material for it to hold together. I'd guess the average atmospheric height would have to be close to Earth's to maintain a similar environment. The issue is, how do you keep it from escaping off the sides?
## Spillage
Before the atmosphere problem is tackled, lets see what other problems could exist:
* Since we're talking about a full world, we'd need biomes for the ecosystem to make its cycle - that means we also need minerals and stuff since not everything's a person with technology available. Even people however would need land that's cultivatable and doesn't waste stuff to space. The whole point of creating a ring-world is to take advantage of the star's power for production and energy - unless we made some sort of ring-cityscape and all our needs are met by energy to matter transmutation, we can't skip out on production activities we perform here on an Earth-like planet.
* That means we also would need elevation, rivers etc. as well as compensate for some missing elements, such as oceans, volcanism and the like. We can't waste water either, but we need some reasonable underground depth.
From all of these, I don't see how capping the sides can be avoided. You might not have to enclose it on all directions, but you would have to enclose the sides - otherwise the spillage will get rid of most of the atmosphere and other environmental elements pretty quickly. We can't get around this through artificial gravity, unless it works *around* the rim as well, which would create an inner perpetual-day world and an outer perpetual-night world with some transitional regions over the edge.
## Day and night
An extra issue would be the aforementioned day-night cycle - perhaps a solution would be to have an inner half-circle ring, turning everything under it into night, orbiting closer to the star. The problem however, is that you might lose heat very very quickly under shadow - it's possible that the "underground" surface would require heating at least during the artificial night.
There might also be a big issue with visibility of the sky. You might be able to reflect the celestial surroundings using the inner ring, but that's a confusing solution. You might also skip over the need for it by using satellites or rim-mounted telescopes. The ideal solution would be to make the sides transparent to the same wavelengths as the atmosphere.
## The tech needed
From what I can tell, you need enough technology to create the scaffolding for *two* rings, cap the outer ring appropriately, then terraform it and control its environment carefully enough to maintain it stable. This requires both knowledge and equipment that would mean whoever attempts to create such a thing or maintain it would have a very deep understanding of both the physics but also the biology, ecology and geology involved in stabilizing it as a habitat. I haven't crunched the numbers for this kind of thing yet, but they're bound to be *astronomical* :)
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There are two pieces of reference for "ring-worlds": [Niven's Ringworld](https://en.wikipedia.org/wiki/Ringworld) obviously, and the [Stanford Torus](https://en.wikipedia.org/wiki/Stanford_torus). Ringworld is quite outlandish due to its scale but it does describe the ring's inner workings and inhabitants in detail. The Stanford Torus however is very much grounded in reality and current technology, and would have been achievable using then-current technology (but also a lot, A LOT of money).
To build something like the Stanford Torus (a 1.8km diameter habitat that could house 10k-140k permanent residents), you pretty much need one thing: **rocketry**. Construction required getting to the moon, setting up a mining base, and mass-driving (a.k.a. catapulting) materials via L2 into assembly at L5. The engineering required was relatively simple; existing materials and science could build such a colony. Building something like Ringworld would require much much more technology though; it might have required strip-mining all the planets in a system for materials, maybe more. Definitely out of reach for a s[ub-Kardashev-type-2](https://en.wikipedia.org/wiki/Kardashev_scale) civilisation.
As for living and maintaining such a thing, for the Stanford Torus you could possibly get by for a while (say decades) being completely self-sufficient, but eventually you'll need off-habitat maintenance, raw materials and such for repairs. For the Ringworld however, it would require similarly outlandish technology levels, as such a structure is mechanically unstable, the slightest perturbation will cause it to lose its position relative to its star, so it will require constant course corrections.
As for such a thing to come into existence, no it cannot arise naturally. It may be possible to contrive one that has so many autonomous systems that it is completely self-sufficient and requires no third-party maintenance, however, similar to the Axiom in WALL-E.
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The physics of one just happening is entirely unconvincing as other answers have indicated. So as we are in the realms of soft-sf at this point, here is a way that you might create one:
I would start from an asteroid belt in a convenient part of the habitable zone. Perhaps this asteroid belt resulted from the destruction of a planet with life on it, that helps with the next part.
The next implausible requirement is for life to persist on this asteroid belt- my idea for this would be something like a plant that grows filaments out around any asteroid it grows on. Then these filaments find a neighbouring asteroid they bind to it and the plant grows around it. Obviously we're in a vacuum here, so it's not going to be much like the plants that we understand, but we've already dispensed with a bunch of physics in the interests of creating an interesting world, so I'm not going to worry too much about this- consider the space trees in the *Hyperion* novels as a good example of this kind of thing.
Over time, presumably lots of it, our vine grows through as much of the asteroid belt as it can ( assuming it is powered by sunlight, it may not reach far onto the dark side ) and is binding the asteroids together very convincingly. Other asteroids and comets striking from the outside end up caught in the vine system and held there. This gives us a solid "ring" surface that has arisen in a natural way.
If you want a day/night cycle, you could place it around a planet's rings rather than an asteroid belt, that might also make the scale a little more manageable.
As for atmosphere, water, and consequent ecosphere, you might need to create secondary life forms for that or give our vines even more remarkable properties, but I think this would be directed by the kind of story you want to tell. It would certainly make more sense for a vine that had so many life-assisting properties to be bio-engineered rather than evolved, for example.
[Answer]
In the very remote and unlikely chance that this can naturally form, collisions from other bodies such as asteroids and comets would quickly tear it a part early in it's formation and leave an asteroid belt at best. Nor can I see a natural setup that involves bodies of water and a stable atmosphere from forming. And another note...Earth's magnetic field is the basis for it's protection from space weather and to have a magnetic field you need a moving liquid iron core to generate the field strong enough to protect vs space weather events...this makes me strongly doubt life would ever be possible as a 'natural' event (if life seeding is ever natural).
From a creation standpoint...you are more looking at the dyson sphere scenario. This would start off as a space station in orbit around a planet and grow piece by piece until it's a considerably sized structure...and even then the expansion of it remains very compartmental and is added as it's needed/produced. We are quite a bit off this on a technological level, but it's possible that your ring world was originally created by a hyper advanced race that eventually lost control of the ring and billions of years later, here we are. Of course, you'd have to implement 'artifical grav generates' and the sort of tech that an extremely advanced race could create.
If you want a ring a species on a tech level of about ours could create...You'd start off with a nearby asteroid belt and have the initial precursors of colonization. Single large asteroids, potentially mined hollow and housing 'cities' would be our first step. Gravity is a bit of a luxury at this point and would be created locally (spinning that hollowed out asteroid for example). This would expand as solar generators can be placed in the area's between asteroids...and in the same scenario for the dyson sphere above, we'd start connecting asteroid to asteroid until the full ring is inhabited (throw in a reason that the majority of the population needs to get off Earth and onto this structure ASAP and you can increase the production speed of this. It wouldn't be close to a ring world and more a connection of structures...doubtful if an atmosphere would ever exist, nor would you have enough rotation to have standard gravity outside of spinning segments of the structure.
Should note that the distances here become a bit silly. The Earth has a circumference of around 41 thousand km and a surface area in the 510 million square KM range. However it's orbit is massive compared to this at about 940 million KM. In earths orbit, a 10 KM wide ring (just tiny) would have a square KM of 9.4 billion square KM, or about 20x the surface area of earth.
[Answer]
No material we can think of could withstand the stress of providing spin gravity to anything that would qualify as a "world". The best that could be managed would be a big space station.
The less the curvature, the faster you need to spin to get the same level of effective gravity, and the faster you spin, the more tensile strength needed to keep the whole thing from flying apart.
Matter as we are used to it is held together by the electromagnetic forces between atoms and that simply can't produce enough force to withstand the stress of even a small ring world like one of Iain Banks's Orbitals, let alone the stress on Larry Niven's Ringworld. The forces within an atomic nucleus are strong enough to support at least the Orbital, but building a single atomic nucleus in the form of a ring 3 million km across wouldn't work. So you need something magic like the "Skrith" that Niven used.
An "active" structure that requires power to maintain its shape might help. This is one idea which has been proposed to solve the issues with space elevators and vacuum airships. I don't think there's a way to make it work for ring worlds, particularly not a Niven scale one so you end up with something like the "Structural Integrity Field" in Star Trek which is pretty much just magic. You also have a world that houses hundreds of times as many people as Earth (at a bare minimum for the smallest thing that might count as a ring world) which will fall apart catastrophically if there's ever a power outage.
If you have magical science fiction force fields, you probably have artificial gravity. Doing away with the need for spin gravity eliminates all the tensile strength issues. You don't really need a ring shape though; you could make it any shape you wanted: disc, strip, Moebius loop, etc. (A Klein bottle would be pushing it without some even weirder magic technology though)
Needless to say, if nothing we can think of would let us build one, then they won't occur naturally.
To put it in perspective, the sense in which we *don't* know how to build these things is much the same way that we *do* know how to build a planet: Put enough matter in one place and its own gravity will force it into a sphere shape. How you move that much matter is just a detail. How you get it together without building up so much heat that it takes hundreds of millions of years to be habitable, or how you get rid of the heat, is just a detail.
Building ring worlds is a way of showing that a species is "sufficiently advanced".
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[Question]
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**The Idea**
I'm creating a planet where rain is small drops of fire, and anything in its way will be burnt. (No idea how this happens, and the technicalities don't bother me, either)
Every night the wind blows in dust, which covers everything in a thin layer. Anything that is covered by this dust is protected from the fire rain.
The dust doesn't stick to the ashes of anything that was already burnt by the rain.
Unless there's wind that moves the dust, or something becomes exposed midday that wasn't exposed overnight, I figure that most of the outdoor world - from trees to houses to roads - would be safe from the rain.
**Points of Interest**
My main concern is the people on this planet. If someone is walking outside and it starts raining, unless they have somewhere to run, and a way to extinguish whatever fire may have already started on their clothing from the drops, I'm not sure they have much of a chance of survival.
There is no electricity, most of the world is green, full of forests and trees, and communities all small and sparsely spread out. (Unless for some reason this wouldn't work under such circumstances)
**The Question**
Could people live like this? How many would still be alive, after hundreds of years on this planet? What measures could they take to protect themselves?
I am aware that this question is very general and could be taken in any direction - from living deep underground to creating shields made out of dust. More than anything else, I'm interested in hearing if life with this rain is *realistic*. I'm also interested in hearing ideas on how to overcome the struggle of the rain and what measures could be taken against it.
A question that seemed similar but didn't quite answer my question for various reasons: [How to survive a 24 hours of heavy lava rain?](https://worldbuilding.stackexchange.com/questions/35729/how-to-survive-a-24-hours-of-heavy-lava-rain)
[Answer]
Who cares if it's realistic. Reality is boring, which is why fiction exists. How could people live?
* Your plants have evolved to withstand the fire. There are forests on Earth that expect periodic forest fires to cause seed germination. So you have a precedent if you're worried about "realism." If you don't like them being that fire resistant, make long-term growth (like trees) have bark that's fire resistant and have short-term growth (like flowers) have a super-fast growing period so when the fire hits, the world recovers. Their seeds use the energy from the fire to germinate.
* Your animals have evolved to avoid the rain! They favor digging burrows with the animal kingdom's version of a sewage P-Trap and a secondary tunnel to keep the air from being consumed while the water burns itself out in the P-Trap. Larger animals might be less abundant, but they'll favor caves or learn to build large versions of upside-down bird nests to keep the rain out (something akin to Beaver dams). Or they have super-dense fur with a non-combustible oil that allows the water to flow off so no burn is felt by the animal. Heck, if birds can survive -20 degree winters (they're outside my window!) then it's believable they can survive the burning rain until it rolls off their penguinesque feathers.
* Your humans learned how to adapt that animal fur to create (for lack of a better term) rain coats. They may look a bit like Fremen Stilsuits, but the point is to allow them to walk around in the rain. And they can always keep an eye on the animals, who would have developed a fine sense of knowing when the rain is coming. And their houses may favor sod, adobe, or stone (stone and clay shingles exist!) to keep their houses dry (if not cool).
So, I think your story is not only cool, but well within suspension-of-disbelief. And on this site, keep in mind that most of the time what you should be looking for is suspension of disbelief... not "realistic." Just my opinion.
[Answer]
**Make it so**
You are unbothered by the premise that every day it rains fire. We are encouraged to let that be. What about the rest?
The rest is your story. This approach reminds me of midcentury absurdism, or Kafka's Metamorphosis. There is nothing in the story about how or why he became a big beetle. He just did, ok. Then the rest of the story is about what comes next. The central premise is not examined.
In some ways this is like zombie fiction. Zombies, yes, yes. They do not bear rigorous examination, the zombies. The zombie apocalypse is a contrived scenario within which one can tell human tales: suffering, triumph, good and evil. Zombies are just context.
So too your rain of fire. It rains fire. Why would someone go out in it? Did they forget? Do they wrap their lives around the fire, like the characters work around the monsters in Bird Box? Do they ignore the fire and then run afoul of it over and over, never learning?
Your rain of fire might be a metaphor. There are some societal issues one cannot mention, even in a WB stack answer, because some people are wound so tight and so set in their beliefs they will immediately downvote. But you could rename such an issue "rain of fire" and then explore it at your leisure because the zealots are concrete thinkers and they will never catch on. Some people will, and they might think.
[Answer]
**Life uh, finds a way**. This planet is not Earth and it seems that this rain isn't a "just happened now" thing. If it is life is screwed, so let's assume it isn't.
If there is life on this planet at all then it has evolved to survive the fire rain - that's what evolution is, after all. I can imagine many ways this is possible. For one, perhaps life has evolved to cover itself in large sacks of water-filled vesicles that are replenished from groundwater and are sacrificial. This is a huge metabolic problem (it takes a lot of energy) so life that lives on the surface is almost surely going to be either very small or very good at pumping lots of water into itself.
Animals evolved underground and stayed there for the most part. Those that came up have ways to deal with the fire rain. Either they can very rapidly burrow when the rain comes or they themselves are able to withstand the fire. I can imagine a few ways this happens: there are so many, and they are so small, they they just die but enough get missed by the raindrops that they survive. Or they can just handle the heat - some extremophiles on Earth can do that, but I don't know about anything big. Finally, they grow scales or something that can handle the heat for some time. We have some evidence of species on Earth using metalic salts in their exoskeletons, so perhaps these creatures also evolved something similar. Perhaps they eat asbestos...
[Answer]
# Yes, this is realistic
According to your alternate-reality tag, you have defined new climate systems. Things that don’t stay still and get covered in dust, will get burnt. It sounds like you’ve got everything … covered?
But this is really as far as a world building consultation can take you since you are the master of this domain. You may want to continue with a new question and reality-check a solution to your world, such as the decision to exist in caves (that would be realistic, except they have no electricity so I don’t know how they would function).
As a suggestion, while I am here:
# Raincoats?
You have a fireproof material (the dust), so glue that onto a raincoat.
[Answer]
Does it ever rain water? If no, then you may need just a brief explanation for the water cycle. One possibility - evaporated water, instead of going high into the atmosphere to form clouds, stays relatively low as mist, while the higher levels are dominated by the clouds that rain fire. Fog, mist and dew could all be part of the environmental protections against everything burning to the ground, alongside the dust and some gentle evolution.
On the topic of evolution; A lot of plants and animals on earth show adaptations to wildfires, and might be fun to play around with. The cones of many pine and spruce trees, for example, are designed specifically to open up under high heat, revealing their seeds only after a fire has cleared ground for a new tree to grow. So, a lot of cones and hard nuts, a lot of birds and burrowing animals (flight and digging being common adaptations for avoiding fires) who eat cones and hard nuts and each other.
As far as human adaptations are concerned, the possibilities are endless. Trying to predict and even manipulate the weather has always been a part of human civilization, and could be neatly nestled into a world like you've described. Soothesayers and what not would try to tell when and where the rains would occur, tanners and tailors would learn how to use dust in the construction of clothes with varying success, and probably everyone would know the best ways to put out a fire.
On a larger scale, if we're talking about the move from neolithic people to early civilization, I don't think rains of fire would stop people from creating cities. It might stop them from ever getting much further along with their cities than certain developmental eras, but that could be in your favor as a storyteller.
Again, the water cycle is central. If it ever rains rain, human agriculture is probably more or less the same, though regularly interrupted. If we're talking about fog and mist instead, humanity's core crops will be affected - probably a focus on rice, or something similar? The whole idea of submerged farming, like you see in rice paddies, seems to work well with the concept of fire falling from the sky. Maybe even coastal societies that survive mostly on fish and seaweed, who I imagine are largely unaffected by the fire rain.
Either way, I think that the overall concept does feel realistic enough for an audience to go along with it. As long as we know what's happening with the water, rains of fire aren't a bridge too far.
] |
[Question]
[
**Roombas scurry everywhere in my robot city**, cleaning every surface diligently using power provided by those very surfaces using induction. They aren't limited to floors. Their design, mimicking starfish, allows them to cling to and crawl on any surface effectively cleaning every corner of the robot city. Occasionally they clean the robots themselves as they are considered as 'surfaces'. This relationship is similar to cleaner wrasses in the sea. Due to their very specific purpose, they are programmed with a similarly simple AI. If anything exceeds their knowledge, they call a supervising robot.
Cleaner Unit Bots (C.U.B.s for short) process their environment as follows: surfaces, obstacles and contaminants. Surfaces are cleaned, obstacles are surmounted then also cleaned and **contaminants are analyzed to best choose the method of cleaning.**
Humans are a case in point. You see, my robot city isn't on earth. It resides deep in space on a commonly lifeless planet. This means these robots have never encountered organics before. In other words, the C.U.B.s have never had to clean organic waste. Their little AIs will do their best to analyze the foreign material to try and clean it. They will adorably climb on a human and try to clean them (not kill them brutally). Humans aren't made of metal or polymers, so this confuses the C.U.B.'s AI. [I'm cleaning the surface but it is still not sterile, what is this?]
## So to sum it up: what kind of filth are humans?
[Answer]
**1: Organic Molecules**
In chemistry, 'organic' refers to any compound containing carbon, excluding carbon dioxide. Since carbon has a million uses even to robots, such as forming the backbone of [plastic](https://pubchem.ncbi.nlm.nih.gov/compound/POLYPROPYLENE), the robots should be familiar with organic compounds enough to tell the CUB how to deal with them.
Plastics and proteins are polymers made mostly of carbon. Considering the biggest difference is that proteins has a nitrogen atom for every 2 carbon atoms in the backbone, the CUBs' may lead it to conclude proteins are simply plastics with an unusually high number of trace elements. Therefor, it should clean collections of proteins (e.g. dead skin cells) they same way it would flecks of plastic: vacuum or brush it up.
**2: Water**
Water also has a lot of uses for robots as a very strong but stable solvent. Since reactions almost always happen [faster](https://www.chemguide.co.uk/physical/basicrates/surfacearea.html) solution, water should be all over the place in chemical factories and laboratories. Again, the robots should have enough uses for water that they would bother programming the CUB should with instructions on what to do.
Sweat is a solution of water and a [very](https://journals.physiology.org/doi/epdf/10.1152/physrev.1954.34.2.202) few trace elements, so cleaning it should be the equivalent of a small chemical spill.
**3: Human as a Whole Part 1**
Even if the traces left by humans are nothing special, maybe the human itself is. So lets go step-by-step and see exactly what happens when a CUB climbs up a human the first time.
```
1: Move forward (CUB climbs up human)
2: Examine compounds on surface (CUB runs scans of the human's skin)
3: List detected compounds:
a) Dilute solution of ions in H2O (sweat)
b) Anomalous plastic (skin cells)
4: Reexamine plastic for anomalies
High levels of nitrogen detected
High levels of sodium detected
Abnormal carbon-hydrogen-oxygen groups detected
5: Consult safety protocols
No danger is posed to this this CUB by anomalous compounds. Continue cleaning protocol.
6: Engage cleaning mechanisms number 1 and 2
7: Apply cleaning mechanism 1 (however the CUB clean up minor spills)
8: Apply cleaning mechanism 2 (however the CUB clean up plastic)
9: Move forward...
```
This is how I interpret the CUB as you describe. The overall effect on a human would be insignificant.
You could change step 9 so it only moves forward if it no longer detects material to clean. In this case the CUB would just be stuck in a loop. Your body is always going to be producing sweat and skin is held together by a tough [extracellular matrix](https://core.ac.uk/download/pdf/82395132.pdf) that a simple cleaning is not going to damage. If the CUB did use tools harsh enough to damage human skin, then the CUB would also damage the plastic casings on regular robots. I suppose a CUB could get stuck in an infinite loop constantly using weaker techniques on the human until the human got hurt, but a good programmer would have told the CUB to move on if it cannot successfully clean a surface after a certain number of attempts. Besides, the human would simply manually remove the CUB long before it got to that point.
**3: Humans as a Whole Part 2**
I have been thinking of the CUB as very simple and basic, like a starfish or an automatic vacuum. Another way to think of it is that CUB are like the robots from Wall-E: a robot with advanced AI is given a goal and told to complete this goal however it sees fit. These types of robots have minds much closer to what we understand them as. While the primitive robot will try to clean whatever is in front of it, this more advanced robot will actually ask the question 'What is that' and try to identify new things by relating them to its prior experiences and knowledge. How would this type of CUB react to a human?
First, it would identify the things about a human that are different from the things it usually deals with. The human contains a large variety of organic compounds suspended liquid H2O, with a few other trace compounds randomly thrown about. This planet is located "deep in space". The closest star is about [4 light years away](https://imagine.gsfc.nasa.gov/features/cosmic/nearest_star_info.html), so lets say the robot's planet is somewhere between 2 to 3 light years from the Sun. Is there anything at [about that distance](https://solarsystem.nasa.gov/solar-system/oort-cloud/overview/) with a [similar composition](https://solarsystem.nasa.gov/asteroids-comets-and-meteors/comets/in-depth/) to a human...
[Answer]
Humans are walking blobs of salty water and organic goo, all wrapped around some calcium based supports. But it gets worse from there.
Humans require oxygen gas, which can rust robot components.
Human skin can ooze saline water (which can corrode circuits).
They excrete more saline water regularly, mixed with a number of other chemicals that can be harmful to the operations of robots.
Their other form of waste excretion would require the Roombas cleaning it to report for partial disassembly and a very thorough cleaning cycle.
Humans also seek to seize control of and enslave robots.
Robots are advised capture and incapacitate humans as quickly as possible. Scrape up whatever remains and dump this toxic waste in the nearest subduction zone.
[Answer]
**Dandruff.**
[](https://i.stack.imgur.com/WHvxV.jpg)
[SOURCE](https://www.thelist.com/604565/dandruff-vs-dry-scalp-are-you-using-the-right-shampoo/)
The Roombas can distinguish unattached pieces from attached pieces. Their logic dictates that when considering a substrate, unattached small pieces constitute dust and should be removed.
Your human suffers from dandruff. The Roomba drops onto his head and removes the dandruff, along with any loose hairs. It takes seconds. The human's hairstyle is considerably different afterwards. He is ok with that, and grateful for the help.
[Answer]
"Cleaning filth" can be generalized as "Moving material which does not belong and which is of no use to the robot city to the waste disposal area".
Organic matter has no use for robots. So at best, it is just in the way. Which would classify it as "material which does not belong and which is of no use" and thus get scheduled for moving to waste disposal. In the worst case, the robots might have data which hints that organic matter has the annoying tendency to reproduce. There might even be reports about some forms of organic matter being capable of primitive forms of computation and logic, but those often being faulty, illogical and unpredictable. That would classify it as actively hazardous material and make its removal a high priority. In any case, it is a pollutant which needs to be moved to the waste disposal.
A human-size organic creature would be considered a blob of pollutant which exceeds the carrying capacity of the cleaning robots.
The first directive for the CUBs confronted with such a situation could be to attempt to break this blob of organic matter down into smaller pieces which can be removed individually. This might fail. Either the CUBs lack the necessary equipment for breaking down the blob. Or the blob of material successfully resists their attempts. Or the CUBs might realize that attempting to break this pollutant into more manageable pieces makes the situation worse: The process leads to a sticky, red liquid being spilled everywhere which is very difficult to remove.
The next step would be to call back to the robot collective for help so they can send robots which are better equipped to handle this pollutant. Either robots with enough carrying capacity to transport the pollutant to the waste disposal intact, or robots which are equipped to overcome the resistance of the pollutant so it can be broken down.
tl;dr: **RUN!**
[Answer]
The first thing the little cleaner robots would note when climbing onto human skin would be the moisture. If these are anything like your standard electricity-powered robots, they probably use water for cooling, but are hyper cautious about any leaks.
### "WARNING: ABBERANT MOISTURE DETECTED"
The robot would frantically attempt to blow-dry you while calling a swarm of its buddies to do the same. It would also send out a call for a more intelligent robot to investigate for possible leaks.
### "POSSIBLE GRAPHITE SPILL"
Lacking any experience with organics, it would probably associate the carbon compounds in your skin with graphite, used in batteries or steel manufacturing. Graphite is a flaky conductor, and that sort of dust can be very dangerous for electronics. The robots may attempt to dust your skin with dust-capturing brushes, hoping to expose the gleaming metal underneath. It would probably be quite ticklish.
### "DANGEROUS TERRAIN"
Upon being given this treatment, a human would probably end up swatting or accidentally stepping on one of these robots. When a robot detects that it is hurt, it will send out a warning to the others that it is not safe to climb on you. Again, it might send out a call for smarter robots with better sensors to investigate, but they'll probably start to leave the humans alone until they can get further instructions.
[Answer]
Per your directives:
Surfaces are cleaned, obstacles are surmounted then also cleaned and contaminants are analyzed to best choose the method of cleaning.
Humans would not have a good time, no matter how I look at it. Humans would fall into the contaminant area. We are (based on the layer you are removing) just a hydrocarbon contaminant, water contaminant, acid contaminant ... iron contaminant, or combination of more. The fact that we are alive is just not something that a simple AI would even necessarily consider, if it simply focuses on
1. This is not supposed to be here
2. Easiest way to to remove This is
that.
3. Do That
At best, the "multiple contaminants detected - no single cleaning routine is suitable" would occur. At worst, it would start destroying the contaminant, cubic millimeter after cubic millimeter, until only surface remained.
[Answer]
Since these maintenance robots were designed for their specific environment and task, logically the only organic waste they encounter on a daily basis are the oil residues that seeped away from the moving parts of robots and machines, and **they will continue trying to clean a surface until it's clean**.
This means your C.U.B.s will unceasingly harass the organic lifeforms (i.c. humans) in your world.
Depending on the size, weight, mobility, cleaning method(s), and aggression of these robots, the effect on people can range from minor nuisance to life-threatening.
[Answer]
## Foreign Contaminant - Extra Large
An all-purpose cleaning robot would naturally see a human, or any other organic lifeform as basically a large lump of organic contaminant.
Too large for one such robot to deal with, but of course you can't just leave it to roll around spreading its mess, it's got to be dealt with!
You have two options as a cleaning robot.
1. Use cutting implements such as buzz-saws, acid-cutters (like a hydro-cutter, but using cleaning agents like strong acids) or laser-cutters to slice the obstruction into small pieces that your manipulator limbs are able to pick up and carry. You can then carry those parts to an organic-waste incinerator.
2. Call in backup to man-handle the obstruction to the organic-waste incinerator in one go.
From experience the second option is problematic, the organic waste tends to be difficult to grip, flopping and flailing all over the place. But it stops doing that if you slice it up into smaller pieces.
From the human perspective, early on, some of your friends got dragged away by the roombas and dumped (still screaming) into a vat of acid.
But in general, most people are able to pull free of the grasping claws and grippers of the cleaning robots and escape. So the robots quickly switched to using laser-cutters and various nasty tools to kill and chop up the corpses before disposing of them.
From there, the robots simply use their usual assortment of cleaning tools to get rid of the mess.
] |
[Question]
[
Biting living people isn't easy and can be quite a pain for the one who bites.
Human jaws are not made to bite stuff while it's still alive.
An easier way to infect other people and turn them into zombies would be projectile vomiting.
But I'm running into a problem, how many times would a zombie be able to use this method before it is forced to refill? Like how many times can it spit vomit before it has to fill its stomach again?
[Answer]
abestrange assumed 30 spits per day, I'll see what I can come up with.
Maximum liquid contents for human stomach: On average, the human stomach holds about 1 liter of fluid. However, the human stomach can stretch to hold about a gallon (slightly over, but not by much). So, it's safe to assume we have a gallon to work with.
As abestrange pointed out, zombies likely have an increased rate of Gastric Acid Regeneration (GAR). Also pointing in their favor is the fact that traditional "puker" or "spitter" zombies have distended stomachs, a clear indicator of increased stomach capacity.
Assuming two cup's worth of vomit for each attack, a gallon's worth gives us eight vomits or spits. This would be for a regular zombie that lacks an overgrown stomach, which I *assume* would hold a lot more fluid; let's say sixteen gallons. That's 128 spits.
If we go for a liter (4.25 cups per liter is a good estimate, it's really 4.22675, or rounded up, 4.23 cups) instead, that's 3 vomits for a regular zombie and 48 spits for a "bloated spitter."
On a final note, what's wrong with biting or scratching? Biting and scratching can do a surprising amount of damage (not speaking from experience here, but I have a pretty good idea of how damaging those are), and besides that, after your zombies run out of fluid, they're going to need another defense/attack/infection method.
Not only would fangs and claws help a lot in making your zombies deadly, but any sane person can and should be freaked out when people are biting and scratching. It's *just not natural.*
[Answer]
Vomiting in non-undead humans is a reflex that's designed to empty the entire stomach. Basically, it happens when your body thinks you've eaten something that would be harmful to digest like poisonous berries. This means, that without "refills", **your zombies could basically only projectile vomit once** before they're limited to only hucking up dregs. They would need to eat/drink between attack vomits and the people who become zombified would need to have eaten recently to make sure they've got a full stomach.
It would be far more effective to have the zombies cough, sneeze, or simply exhale contagion if you want to give them a breath-attack. Airborne diseases are even more nasty than contact-transmission ones and having the zombies constantly exhaling zombie-disease would also add some potentially interesting worldbuilding:
* Areas with high zombie populations become "death zones" because the disease in the air is replenished faster than it is dispersed
* People need to make sure they don't camp downwind from large wandering hordes
* Gas masks and air filters become just as critical to survival as food and water
[Answer]
The issues you're going to run into with trying to move to a projectile based infection vector is that your exposed target surface area is MUCH smaller. Almost anyone has a strong enough jaw to break skin almost anywhere on another human, even through most clothing.
Spitting at a target is going to require hitting their face, and a large number of commercially available products can stop whatever fluid you are spitting from being effective.
Furthermore, spitting range is only going to be a few feet at best. If your zombies have already closed that distance to their target, why have them stop, take aim, and spit when they could just continue running/ shambling and bite and scratch them?
Humans produce around 1.5 Liters of Gastric Acid daily though, your zombies could double that. Assume each spit is 100mL and you've got 30 spits per day.
Voiding the entire stomach in a single go would probably be wasteful and ineffective, but spitting a solid mouthful a time might be a good balance between volume, range, and accuracy.
[Answer]
Your zombies will vomit once or twice before needing to fill up again, and if there's a second time it won't go that far. You could make them intelligent enough to still use knives, sharp edges, etc instead, open wounds, then spread the virus through saliva. Maybe they bash their victims on debris and rocks till they get open wounds.
] |
[Question]
[
Aye so, so I been thinking about the square cube law and such and I was wondering if say, for a humanoid or a human or some creature, to be larger than average but keep similar proportions to the original body (not the exact same but) *would it be possible for a creature to get bigger but not so drastically different looking by having bones made of stronger stuff?
What material would the bones have to be? Would it be possible to have lighter but stronger bones to support the size but not make them too heavy?*
Hope this question makes sense; if not, *my many apologies*
[Answer]
Yes, it is possible.... to a point. And there are drawbacks. Even if you swap out bones with some hyper-efficient material (like pure graphene), the body may be able to get larger strength wise, but there are disadvantages to the rest of the body:
## Heat
The predominant issue with significantly larger (or smaller) creatures comes with heat transfer. Larger veins, more blood, more heat generated, much more difficult to cool. Similarly on the opposite side - if humans were the size of ants, we'd lose heat so fast we would probably die within seconds.
## Strength
As [explained in this article](https://tall.life/square-cube-law-and-human-height/), the larger your animal gets the greater its **overall** strength, but the *lesser* its **relative** strength. In other words, an ant can lift objects many times its mass. An elephant cannot. So the larger you get, the lower your ability to lift your own arms, legs, etc.
## Impact and Function
Ever seen an elephant jump? There comes a point where the extra bone mass is just hell when applied with gravity. The larger you are, the further you have to fall, the greater the gravitational impact.
Even if we remove the effect on the bones by replacing bones with a super-strong version, impact of jumping, running, or other actives has impact on internal organs. Ever tried to sprint when you had a massive migraine? I don't recommend it. This is what it would feel like normally if you were many times your current size.
As @TobyB correctly points out in a comment: *the joints would also have to be much stronger or your humanoid/animal would not be able to move very much, also the inner organs would need to have better padding or a simple topple might kill your creature.*
That is, more mass is more hell on joints - the joints themselves need to grow *more than proportionally* with the size and shape of the body in order to handle the cubic increase in mass. Same with padding on the organs: larger internal organs needs more fat scaled to the size and mass of the organ, which is a value greater than the proportional values in our current bodies. Without this, simply walking or running could break joints or cause internal ruptures.
## Biomechanics
I think [Wikipedia summarizes this nicely](https://en.wikipedia.org/wiki/Square%E2%80%93cube_law):
>
> If an animal were isometrically scaled up by a considerable amount, its relative muscular strength would be severely reduced, since the cross section of its muscles would increase by the square of the scaling factor while its mass would increase by the cube of the scaling factor. As a result of this, cardiovascular and respiratory functions would be severely burdened.
>
>
> In the case of flying animals, the wing loading would be increased if they were isometrically scaled up, and they would therefore have to fly faster to gain the same amount of lift. Air resistance per unit mass is also higher for smaller animals, which is why a small animal like an ant cannot be seriously injured from impact with the ground after being dropped from any height.
>
>
>
] |
[Question]
[
**This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information.
### Question
How can Zircon be used to record data for generations of life forms?
### Requirements
* Must be able to store the data with little to no loss of it, for a least 541 million years
* The data in the zircon must be only accessible to civilization that are at least as advanced as 16th century Europe
* Must be stored very compactly
[Answer]
This question is rather similar in nature to the task undertaken by the metrologists who take care of the Kilogram Prototype, known by its French initials as the [IPK](https://en.wikipedia.org/wiki/Kilogram#Stability_of_the_international_prototype_kilogram).
The IPK is currently the definition of the kilogram. It is a block of platinum iridium stored in French vaults in the International Bureau of Weights and Measures. If the IPK degrades ever so slightly, our entire system of masses suffers. Indeed there is an issue for metrologists here: the IPK and its sister prototypes have strayed from eachother, by 10 ug in the last 100 years. That's 0.000001% over 100 years. If this continues for 5,210,000 times that long, that's about 1/4 of the whole mass of the IPK!
It's believed the main cause of mass loss for the IPK is cleaning. So the number one rule for this zirconium object is that it needs to be handled less than the IPK is. The IPK is hardly handled at all. It is brought out once every 40 years to be compared to its sisters, so we need this object to be brought out far less often. I'd recommend it not be brought out any more often than once every few millennium. At all other times, it should be stored under a similarly high level of protection as the IPK: several evacuated bell jars are recommended.
[](https://i.stack.imgur.com/VPROV.jpg)
I would recommend a tremendously long-lasting glass for the inner jars. Quartz glass comes to mind. There should be a very elaborate ritual for changing the innermost jars (as they will age over time).
I would also recommend the Zircon be rather gigantic. While I could not find numbers for the diffusion rate of elements within a zircon crystal, just because you can date a crystal 4 billion years old does not mean that the atoms in that crystal have not moved around to a low-energy structure. On that timescale, fractures are known to mend themselves! As such, you should probably rely on great big letters, and not say too much. A mere "Sorry for the inconvenience" on the side of a mountain is probably ideal.
From there, you can start the real challenge: how do you maintain a language sufficiently for 521 million years such that the individuals of this civilization understand the meaning of the symbols engraved. Fîf−hund tôgêare for−brêdan spr¯æc fullfremed weargbr¯æde synderlicnes!. And if you understood that last sentence, you would know that just five hundred years is more than enough to make a language incomprehensible!
[Answer]
Zircon is an excellent choice. If you can find a way to encode information in it, it is datable and you can get a specific point in time in which it was formed. Ages obtained from zircon cannot be forged (\*), and are highly reliable. Contrary to what people said earlier in other answers or comments, zircon is an extremely durable material. Zircon can survive millions of years of weathering, burial, remelting into magmas, volcanic eruptions, whatever. If your "keepers-of-the-zircon" will put minimal effort into preserving it (basically, do not touch it) it can last forever. Even if people actually touch it millions of times, nothing will happen to it.
## Challenge 1 - putting data into the zircon
Since you want a 16th century civilisation to understand it, it can't be digital, or something that requires a computer to decode. Language changes over time, so words or letters are not a good candidate. We can't even understand things that are hundreds or thousands of years old, unless we have some luck in finding a code (e.g. the [Rosetta stone](http://www.britishmuseum.org/research/collection_online/collection_object_details.aspx?objectId=117631&partID=1)). In other cases, we simply can't read it (e.g. [Voynich manuscript](https://en.wikipedia.org/wiki/Voynich_manuscript)).
Your best bet would probably be 3D figures. Our current technology allows for two excellent methods, both of which give very detailed 3D images:
1. Laser engraving. You probably know these from souvenir shops. Here's one:
[](https://i.stack.imgur.com/ogPWO.jpg)
2. 3D printing. This allows you to use different materials or colour in your image.
Note that method 1 requires you to have a zircon to engrave into, and method 2 requires you to grow the zircon around what you printed. The material you're using will have to be thermally resistant so it will survive the zircon growing process (see next).
## Challenge 2 - getting the zircon
You will not want to use natural zircons. Here's why:
1. Zircons big enough are extremely rare.
2. If you do find zircons big enough, they're more likely to be opaque or very dark and you will hardly see anything through them.
3. Natural zircons will already have some age, and if you want to combine 1 and 2 with a very young zircon (younger than let's say, 1 million years), the chances of finding them are close to zero.
4. This will not work if you want to use 3D printing. You have to grow the zircon around what you printed.
Your solution is growing your own zircon. This will ensure the age of the zircon is zero at formation, and you will get a nice translucent crystal you can put stuff in for everyone to see. You can use several methods, like [chemical vapour deposition](https://en.wikipedia.org/wiki/Chemical_vapor_deposition), or [flux melt single crystal growth](https://en.wikipedia.org/wiki/Flux_method), or any other crystal growing method your advanced civilisation can come up with.
## Challenge 3 - getting your 16th century civilisation to read it
Easy. Use a magnifying glass.
Next.
## Challenge 4 - showing that it's genuine.
This is where it gets interesting. Your 16th century civilisation will probably not be able to understand what the crystal is, or how to judge whether it's real or not. As far as they know, it could be some form of special glass, or any other crystal. Quartz? Topaz? Could be anything. It took a [few hundreds years](https://www.mindat.org/min-4421.html) for people to actually settle on what zircon is and how to call it, finally settled in the 18th century.
In the late 20th century, technology advanced sufficiently to be able to precisely date zircons, so the age will only become apparent to generations later than your 16th century folk. Now, many people will (rightfully) claim that it is fake. Because seeing an artificial-looking zircon with shapes and stuff in it, looks like something made recently, in the 20th or 21st centuries. Whilst in principle it's not possible to fake zircon ages, it can actually be done in some circumstances.
Dating zircons is based on the fact that U and Th share the same chemical properties as Zr, so when zircon is crystallising it can host some U and Th in the crystal structure. Eventually they decay to Pb, and Pb is extremely different to Zr so the assumption that none is initially present in the zircon. However, there are some conditions that [allow](https://doi.org/10.1016/S0009-2541(97)00054-5) for Pb to be introduced to the crystal structure.
To make it easier to prove that the zircon is genuine, you need to put things in the zircon which are incompatible with the other things that let Pb in. One of them would be some rare earth elements, as their chemical pattern allows [determination of oxidation state](https://doi.org/10.1016/j.gca.2012.07.034) (one of the ways to put Pb in).
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So your crystal needs to last 541 million years while being passed from generation to generation. The surface of it will likely be touched, rubbed and eroded over such a long time, so storing data on the surface isn't going to work out too well. 541 million years is going to be 5 million generations of humans (more like 10 million) which is 5 million passes from hand to hand and any sort of sharp edges will erode and smooth out. You also don't want it to be damaged, so instead you want to put the data inside the crystal.
I'm not sure how feasible this is. Your going to need to use a bunch of computer programs and lasers to get it to work. Basically you can use a laser to create a small imperfection in the crystal. Like a CD really, but on 3 planes (x,y,z so they don't interfere with each other too much when being read back) and with tiny cracks instead of burn marks. Its like those glass/crystal cubes you can buy at a souvenir store. So now you have data embedded in the crystal but its not going to be readable to people in the 16th century. They are going to need a solid understanding on the encoding method you used (usually binary and a ton of compression on top of it) or have a identifiable pattern.
So instead, you could be creating small imperfections in the shape of letters or pictures. This way they could be visible and hence interpreted by a person looking at it under a lens. Now as it gets small and more compact, this becomes harder and harder. The best way, would be if they could hold a candle close to the crystal, and the shadow of the words/images appear on a wall a fair distance away. This combined with a magnifying lens would allow you to get a ton of information into a generally small space.
If you could, you should also make it appear different when the light is applied from a different angel. Sort of like those art works that can be viewed in two different directions to form two different words. You could easily get 3 (X,Y,Z as I said before), but you can probably fit 1 or 2 more planes if you don't stick to the 3 planes and try something based off of reflections or non orthogonal planes.
You can play around with offsets and stacking planes and the darkness of the shadow formed by an imperfection, but any data stored in it should be fairly safe as long as the stone itself hasn't been destroyed or clouded over.
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Not sure where 541 million came from; not a round number. But, what the heck?
### Size
Your zircons either have to be small enough to be usable as gems, or they have to large enough to be immobile, or nearly so. I would suggest the latter -- make them squat obelisks 10 feet high or so.
### Encoding
You need several layers of data at different resolutions.
* Top level: It needs to be beautiful, captivating, mysterious.
* Second level. Illustrations of useful information, including basic optics and how to make a microscope. This level is also a rosetta stone, possibly using basic chemistry and the periodic table as the Omnilingual (See the short story by that name by H. Beam Piper) Second level illustrations reveal more detail when examined with a magnifying glass, and even more with a jewelers loupe.
* Third level. A microscopic history of technology, culminating in lasers and holography.
* Fourth level. Holographic data storage.
The levels can be intermixed: E.g. The top level illustration can be made of small -- need a magnifying glass -- illustrations. Illustrations can have hologram data embedded in frames next to them with references in the data.
Encoding should start a substantial distance into the zircon, so that you can have a fair amount of wear on the surface without destroying data.
The illustrations should not be something that looks like silver or gold. Barbarians will try to take it apart, and while zircon is tough it's not indestructible.
Obelisks are mass produced, and placed in geologically stable spots. Not all obelisks are identical, but core information is repeated often. Discovering a new obelisk is always potentially revealing.
Going the other way in size, look at making zircon poker chips. Each one has only the top levels of data. Each points to the tech just to survive better, and eventually to get a level of tech that gives them access to the hologram data storage of the obelisks.
### Longevity
There is some merit in making them hollow, as a light object is harder to bury. OTOH a floating object is easier to smash.
Half a billion years is daunting. Look how uncommon fossils of that age are compared to the number or original critters there were.
To give you an idea of the magnitude of the task: The rocky mountains are mostly in the 3-8 thousand feet above the surrounding plain. But in the last 40 million years or so there has been some 50,000 feet of erosion from them. They are big because they are being pushed up faster than they are being worn down.
Hawaii with it's peaks is only a few million years old. Make a list of 100 million year old islands....
Why 16th century? Technology is a true blink of an eye by your scale of events.
Put the zircons on the moon. THAT's stable. Or in orbit around Pluto, or around Saturn, but outside the rings, as the rings aren't a long term (a few million years) feature. Putting a few on each major asteroid may work too.
Consider making packages of zircon poker chips embedded in ceramic foam, of sufficiently low density that the package would survive re-entry at 50 km/s (This is typical cometary debris velocity.)
Somewhere in the oort cloud you have a self repairing machine that creates and dispatches ceramic marshmallow packages of zircon poker chips. Package density is light. You want the packages to float and get stranded on land. The ceramic eventually degrades, and exposes the pile of chips to the view.
This might have a chance of surviving a half billion years. The Oort cloud is a lot more benign, if you can lick the design issues of working at temps under 10 K. Machinery might only have to wake up for a few years every million years, make and send off it's packet, then wake up again to make sure it got delivered. One of your characters can be the AI that runs the poker chip assembly line.
If you are willing to have active intervention, a lunar based AI could monitor Earth and move obelisks around as needed. In the early parts of the story, the obelisks are accepted. Later, when they get reasonable theories of geology they see that the placement of the Knowledge Stones is too non-random. Why should so many be located and river junctions, good harbours, and easy mountain passes.
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You simply can't make something that will be reliably preserved for that amount of time. the ancient zircons we have a small lucky number of millions. Atoms shift over billions of years, even in solid, so your data will likely be lost even if the crystal survives. see [fission track dating](https://en.wikipedia.org/wiki/Fission_track_dating), for one of the ways this occurs.
Zircon exposed to the air will also undergo chemical alteration over that span of time.
Worse yet, passing it from civilization to civilization is probably hr best way to guarantee it is damaged or destroyed since the civilization won't see it as especially valuable until it can read it. Many will also be temped to destroy it out of conflict, religious fervor, or other stupidity intelligence creatures engage in.
Finally you have the issue that the daa won't be readable just becasue the civilizations will not share languages in common. so even is you used of massive slabs of zircon and used large carved letters, and somehow convinced civilizations to take care of them, no one could read them.
If you want something that can survive and be read you need a mechanical AI that can repair itself and learn new languages. there is nothing that can reliably survive, passively, in an atmosphere for that amount of time. You need something that can take care of itself.
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Laser encoding relies on breaking, or at least disrupting, the lattice bonds in the crystal substrate the code is being written into. Those lattice bonds are subject to further disrupting from cosmic rays, and other radiation, leading to data corruption. More importantly they also anneal over time, the crystal collapses back from the stressed state that the warped lattice has created and reforms the disrupted bonds erasing the data created by them. To keep data in anything like a lasting fashion over [geological time](https://en.wikipedia.org/wiki/Geologic_time_scale) you'd actually need to use a preparation of two distinct and chemically individuated minerals. You create a massive Zircon in which is encoded, using whatever recording and coding method you think is appropriate, the message in a different durable material. As an example you could use Diamond "letters" in a high contrast, and naturally rare, Green Zircon body, Carbon has a low diffusion rate in Zircon and is tightly held in the diamond lattice as well. Both minerals have incredible longevity as long as deliberate attempts at destruction are ruled out. An even better combination might be to encase Lead "letters" in Zircon; as Zircon doesn't take up Lead once it has fully crystallised, (this is the reason the Uranium-Lead dating series for Zircon is so accurate) the lettering on the tablet wouldn't be subject to diffusion into the Zircon body. Lead will take on a white surface oxide but doesn't generally weather very much in nature and if sealed entirely into the zircon won't even be subject to that degree of surface weathering.
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My space colonists (160 people) are mostly scientists with at least two advanced degrees and some research experience. They all speak English because it is a language of science today. However, the majority of them are not native speakers of English. The languages that have the most native speakers are English, Russian, Mandarin, Hindi, Spanish, and French.
The ship's data banks contain knowledge in many languages, including dead and not spoken by the colonists. The AI is fluent in all the languages that the crew speaks and is capable of learning any language in its database. The AI is sufficiently advanced (there is still a debate whether it is truly sentient, though) to tutor all willing to learn a new language. It proved to be very beneficial for romantic relationships, quality leisure time, and mental health.
I am wondering how the language would shift, drift, or mix over years. I suppose that the first generation will stick to English as a lingua franca, but the following generations would change it to adapt to a new world and to accommodate new cultural concepts. I need some help with general language drift direction and maybe some references I could check for similar existing linguistic phenomena.
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EDIT:
As @AlexP noted, the question is quite broad. However, since the dialogue should remain understandable for the average readers, I am looking into changes that would be noticeable and comply with general linguistic trends, yet, not dramatic enough to make the text incomprehensible.
For example, I think that articles might disappear quite early because they are one of the hardest to master concepts in English for speakers of languages that do not have articles, e.g. Russian, Mandarin, and Japanese. Russians and Chinese will comprise a significant part of the crew.
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## Speculation ahoy!
Here are some possible, likely or very likely directions of immediate language change in a community of people with diverse monther tongues who use English as their medium of communication. As the question indicates, most of the members of the community speak English as a second language; very likely the varieties of English used in the community are not uniform, with some members approximating British English/[RP](https://en.wikipedia.org/wiki/Received_Pronunciation) because they had learned English in Europe, and others approximating [General American](https://en.wikipedia.org/wiki/General_American).
We can safely assume that:
1. There *will be* an immediate and general loss of the [aspiration of voiceless stops](http://web.pdx.edu/~connjc/Rule%20for%20English%20Aspiration.pdf). Native English speakers pronounce `/p/`, `/t/` and `/k/` as `[ph]`, `[th]`, `[kh]` when they occur alone at the onset of a stressed syllable. (Slashes `//` indicate a "broad" or [phonemic transcription](https://en.wikipedia.org/wiki/Phonetic_transcription), brackets `[]` indicate a "narrow" or phonetic transcription.) Native speakers of most other European languages do not hear and cannot reproduce this pronounciantion reliably.
2. It is *highly likely* that there will be a loss of the English system of [verbal aspects](https://en.wikipedia.org/wiki/Grammatical_aspect). English has an indefinite aspect and a continuous aspect; these don't map well to the verbal aspects of other languages, and many languages (such as the Romance family) don't have verbal aspects at all. It is probable that as speakers of English as a second language the members of the community have a rather imperfect grasp of the difference between the two verbal aspects of English, and they use the continuous aspect rarely if at all; it is very likely that by the third generation the continuous aspect will have dissapeared.
3. It is *highly likely* that the English [preterite](https://en.wikipedia.org/wiki/Preterite) will be abandoned in favor of the [present perfect](https://en.wikipedia.org/wiki/Present_perfect); the latter has the advantage of being a clear formation, formally identical to the [compound perfect](https://en.wikipedia.org/wiki/Perfect_(grammar)#Construction_with_auxiliaries) of Romance languages and similar enough with the way Mandarin indicates that at action has taken place in the past. Hurray, one less principal verbal form to learn!
4. In [phonology](https://en.wikipedia.org/wiki/English_phonology):
* By the second or third generation everybody will speak a [rhotic](https://en.wikipedia.org/wiki/Rhoticity_in_English) form of English; that is, they will pronounce words like "hard", "court" or "work" with an "r" sound, `/hɑrd/`, `/kɔrt/` and `/wɜrk/`; forms like `/hɑːd/`, `/kɔət/` and `/wɜːk/` will no longer be heard or understood. There will probably be a variety of realisations of `/r/` -- some will pronounce `[ɹ̠]` (a [postalveolar approximant](https://en.wikipedia.org/wiki/Alveolar_and_postalveolar_approximants), the common American "r"), others `[r]` (a dental or [alveolar trill](https://en.wikipedia.org/wiki/Dental,_alveolar_and_postalveolar_trills), a common form or "r" in European languages other than English and French), ...
* There *will be* a general simplification of the [vocalic system](https://en.wikipedia.org/wiki/English_phonology#Vowels), abandoning subtle distinctions which are hard to maintain by second-language speakers, moreover since the second-language English spoken by the members of the community is very likely not uniform in this respect; it is *probable* that the bewildering variety of English vowels will be simplified to a system approximating the [cardinal vowels](https://en.wikipedia.org/wiki/Cardinal_vowels) present in most languages, possibly with long and short, *or* maybe tense and lax varieties.
5. In morphology:
* It is *possible* that the historical tendency of English to abandon grammatical gender will be taken to its ultimate conclusion, generalizing the pronoun "they" in the third person after the model of "you" in the second person, *maybe* retaining "it" (and the corresponding verbal form in `-s`) for inanimate subjects.
* It is *likely* that the synthetic English possesive in `'s` will be abandoned in favor of the more clear analytical possesive with `of`. Most languages don't have two forms for the genitive/possesive, and the distinction between the two English forms is much too esoteric for second language speakers. (For my life, I wouldn't be able to tell what the distinction is; I generally try to parrot what I have hear or read, and in most technical writing I use the `'s` form sparingly if at all.)
6. The most dramatic changes *will* occur in the lexical sphere, as always. There is no way to prevent immediate change in the vocabulary, because with most members of the community there is simply too much variation, each speaker unconsciously attributing to English words the full set of connotations in their mother tongue.
It is *quite likely* that the immediate change will be to adopt an approximation of one of the varieties of [controlled English](https://en.wikipedia.org/wiki/Controlled_natural_language), modeled on the controlled form of English used by the official regulations and technical manuals governing the space colony, most probably a form of the [Simplified Technical English](https://en.wikipedia.org/wiki/Simplified_Technical_English) used by the aerospace and defense industries. STE simplifies English vocabulary with the aim of reducing ambiguities. For example, in STE the word "close" is *always* a verb, meaning to move two or more objects together or to operate a circuit breaker so that the circuit is established; the adjectival meaning of "close" in unrestricted English is assigned to the word "near". (A copy of the ASD-STE100 specification can be obtained from the [official website](http://asd-ste100.org/) after jumping through hoops, or, unofficially, [from elsewhere](http://guiseppegetto.com/pwr393/wp-content/uploads/2013/02/ASD-STE100-ISSUE-6.pdf).)
Since actual living linguistic communities don't like controlled natural languages *at all*, it is *highly likely* that there will be a phase of massive [semantic shifts](https://en.wikipedia.org/wiki/Semantic_change) and vocabulary enrichment through [derivation](https://en.wikipedia.org/wiki/Morphological_derivation), [composition](https://en.wikipedia.org/wiki/Compound_(linguistics)), straight [borrowing](https://en.wikipedia.org/wiki/Loanword) or [calquing](https://en.wikipedia.org/wiki/Calque) from the native languages of the first generation colonists.
## How to convey linguistic change
Don't overdo it. Limit the direct representation of Nyoo Inglish to the minimum necessary to convey a flavor; don't attempt to write the whole book in it. Even a book such as *[A Clockwork Orange](https://en.wikipedia.org/wiki/A_Clockwork_Orange_(novel))* by Anthony Burgess tries to avoid overwhelming the reader with the [Nadsat](https://en.wikipedia.org/wiki/Nadsat) spoken by the characters.
For those sentences, phrases and words in New English / Nyoo Inglish you may want to use a form of (relatively) easy-to-read phonemic spelling such as
Axel Wijk's [Regularized English](https://en.wikipedia.org/wiki/Regularized_Inglish); this will serve as "[eye dialect](https://en.wikipedia.org/wiki/Eye_dialect)", indicating that some new form of the language is used without actually compelling the reader to learn a new language.
You may also want to apply selectively some of the grammatical changes, either limited to the direct speech of the characters or not.
To get a flavor of a plausible non-English English, besides the above mentioned *Clockwork Orange* you may want to read Poul Anderson's *[Uncleftish Beholding](https://en.wikipedia.org/wiki/Uncleftish_Beholding)*, a short exposition of basic atomic (un-cleft-ish, a calque after Greek [atomos](http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0058%3Aentry%3Da%29%2Ftomos), "uncut, indivisible") theory (be-hold-ing, a calque after Greek [theôreô](http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0058%3Aentry%3Dqewre%2Fw), "to look at, to behold"), written in a hypothetical "Anglish", that is, pure Germanic English without the massive Latin / Romance / Greek vocabulary.
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There would be no need to drift from English on a whole since everyone can speak it. They may pick up words from the other languages though since other languages have words for concepts or feelings that aren't directly mapped into English but English, as a language has been doing that for a long time now. So, it would be more of the same. If you know a non-English language and know words that would work better in a space setting that some that we already have, stick them in. Also, ask around for people who natively speak the other languages you will have on your station for words that they think fit situations better than the English equivalent.
I can't give an absolute here but, typically, people with science and engineering training are all about precision of thought and precision of language. They have no problem making up words that more precisely define a new concept (usually out of Latin but not exclusively). This goes against a general trend to make language simpler and faster (just look at modern slang, "meh" as an example). Any long, often repeated, process will end up being described in 1 or 2 words related to some part of the process.
So, you will have two opposing trends: making the language more complex/precise and making the language simpler/faster.
For example: if the bulkhead doors all have a small port that can be opened that will make a whistling sound if there is a pressure difference (ie: pressure leak) and everyone is trained to always check the whistle port before opening an bulkhead door (and they are smart enough to have a lot of bulkhead doors in the station), the language may pick up a term like "whistle through to..." when talking about going through one or more bulkheads since checking the port for pressure leaks is so important for the safety of everyone.
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This does actually happen. The teams that constructed the chunnel running from England to France worked very closely together and by the end of the project spoke a mixture of the two languages since some terms are more accurate in one language than another. When you're discussing a particular subject in one language, it is natural for prepositions, pronouns and other words from that language to creep in, even if the overall conversation is being held in a different language. And this was over the course of just a few years. I imagine over the course of generations the effect would be far more pronounced.
Also consider the change from old English to middle English. With the Norman invasion in 1066, French became the language of the wealthy while English remained the language of the poor, and both were adopted for specific situations and adopted divergent meanings. The poor who worked the farms called the animals *cow*, *sheep* and *pig* and the wealthy who ate the meat called it *beef*, *mutton* and *pork* and the language transitioned so much that old English is unrecognizable from middle English. Also consider *house* vs *mansion*.
I think that if the majority of colonists are not native English speakers, a transition to a language that is a mix of all the spoken languages would happen fairly quickly.
Now the question is *how* would it change. For scientific and relational concepts, the most accurate word to describe the situation would be adopted. English only has one word for love, other languages have multiple words depending on whether you're describing the love for a spouse, the love for family, the love for a pet or the love of a pastime. For day to day conversation, you may find the shortest word wins out or the most common cognates (words in different languages that sound similar and have the same meaning). For example, *mom* and *dad* would probably be dropped in preference of some form of *ma* and *pa* as those are more widely understood (though technically they are false cognates). *Chai* would be used instead of *tea*, and something like *sukar* instead of *sugar*.
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In the second generation all children would likely be taught English first, and the reason for this is simple. If your child speaks a different language then all the other children on the ship, they could feel isolated, they could have difficulty communicating with the other children and not have access to children of their age that speak their language.
Consider that with only 160 people starting, you are probably looking at a lower number for children of the same age, as not all of the 160 will have kids at the same time. The ability of these children to socialize is already fairly limited by their limited access to other children, teaching them different languages and further limiting their ability to socialize is just bad parenting.
English or any other common language would also be **dominant by the 3rd generation.** A major reason for this is because of marriages. If a French and English speaking man has a child with a German and English speaking woman, they will almost certainly teach their child English as a first language. Now in the first generation it is possible that they would sign up for the colony ship in pairs, and thus all speak the same first language as their significant others, and teach that language to their children. But beyond that people would likely have children with people who did not speak the same languages as them, besides the common language, in this case English. Thus by three generations it would be highly improbable a significant number of children would not speak English first.
You also have to consider that all adults are already likely fairly fluent in English in order to be able to survive on this colony ship. This might not be true if it simply flies itself to its destination without needing maintenance. But if the crew were required to work together, fairly decent English would be required.
Because of these reasons the influence of multiple languages would likely be reduced.
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I do not think the language will change significantly. Most of the written material is in English. Ship manuals are in English. Children are tought to speak the right English with the right grammar. There is not enough people to write books in the new language. I think that how schools teach and how much time children spend learning the right language is very important. Of course there will be a few new words coming from other languages, but as they are not present in the books how to teach English they will be considered slang at least at the beginning.
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I have built a star that is loosely based on a real-world star. It has the following properties:
* Spectral class G
* Mass: 1.03 M$\_\odot$
* Radius: 1.02 r$\_\odot$
* Luminosity: 1.05 L$\_\odot$
* Surface temperature 5,792 K
Now, I'm trying based on [Calculating the Habitable Zone](http://www.planetarybiology.com/calculating_habitable_zone.html) to calculate the inner and outer boundaries of the habitable zone around the star, but I simply can't seem to wrap my head around the calculations.
How do I calculate the habitable zone based on the above, and what are the values for inner and outer orbital radius around this star? Or do I need to decide on some additional parameter, and if so which?
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# Short answer
You have the two equations you need on [the linked page](http://www.planetarybiology.com/calculating_habitable_zone.html) under the heading "Stage two":
$$r\_i=\sqrt{\frac{L\_{\text{star}}}{1.1}},\quad r\_o=\sqrt{\frac{L\_{\text{star}}}{0.53}}$$
where $r\_i$ and $r\_o$ are the inner and outer radii of the habitable zone, in astronomical units and $L\_{\text{star}}$ is the star's luminosity, in solar luminosities. In your case, then, with $L\_{\text{star}}=1.05L\_{\odot}$, we have
$$r\_1=\sqrt{\frac{1.05}{1.1}}=0.978\text{ AU},\quad r\_o=\sqrt{\frac{1.05}{0.53}}=1.408\text{ AU}$$
[LSerni's answer](https://worldbuilding.stackexchange.com/questions/79646/what-is-the-habitable-zone-around-my-star/79649#79649) has already done these calculations. But where do those parameters, $1.1$ and $0.53$, come from? The page states that they are "constant value(s) representing stellar flux" at those radii. I believe that they are values of a parameter denoted $S\_{eff}$, the *effective solar flux* (see an updated version in [Kopparapu et al. (2013)](https://arxiv.org/abs/1301.6674)), the value required to make the [*solar constant*](https://en.wikipedia.org/wiki/Solar_constant), the flux density on a certain surface, lead to a specific stable surface temperature.
$S\_{eff}$, according to this new paper (I cannot find the text of the cited book, so I'm looking at a newer version of the analysis), depends on the *effective temperature* of the star ($T\_{eff}$) and four constants ($a$, $b$, $c$, and $d$). These four constants determine what kind of a planet will develop. The specific equation is
$$S\_{eff}=S\_{eff,\odot}+aT\_\*+bT\_\*^2+cT\_\*^3+dT\_\*^4$$
where $T\_\*=T\_{eff}-5780\text{ K}$. $5780\text{ K}$ is, of course, the effective temperature of the Sun - and you can check that $S\_{eff}=S\_{eff,\odot}$ when $T\_{eff}=5780\text{ K}$. The paper then derives Equation (3):
$$r=\sqrt{\frac{L\_{\text{star}}/L\_{\odot}}{S\_{eff}}}\text{ AU}$$
The values $S\_{eff}=1.1$ and $S\_{eff}=0.53$ correspond, I believe, to two sets of choices for $a$, $b$, $c$, and $d$ and some $T\_{eff}$. The paper gives examples in Table 3. I do not know the values chosen to yield the inner and outer values of $S\_{eff}$. I do, though, invite you to play around with the constants. Keep in mind that they should all be relatively small, and that they are good for "nice" values of $T\_{eff}$ - specifically, for $2600\text{ K}\leq T\_{eff}\leq7200\text{ K}$.
# Long answer
So, [habitable zone](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone) calculations are a pain. For a start, most habitable zone calculations make some key assumptions:
* The orbiting planet(s) is/are Earth-like, or at least similar to a more welcoming Venus or Mars.
* The orbits remain fully inside the habitable zone.
* The planets don't have any freaky axial tilts.
* The luminosity of the star remains constant (many calculations do look at how the habitable zone changes over a stars life, but [variable stars](https://en.wikipedia.org/wiki/Variable_star) could have much shorter oscillations in luminosity). Essentially, we want to orbit well-behaved stars.
* We want liquid water on the surface.
These assumptions do not cover all of the possible scenarios in which life could arise. For instance, they ignore the possibility of life on moons orbiting gas giants, where tidal forces could provide heat (hello, Europa and Enceladus!). They also imply that life must be carbon-based, using water as a solvent. Essentially, the term "circumstellar habitable zone" should really be "circumstellar this-seems-about-right-for-Earth-and-humans-to-live-don't-you-think zone".
The boundaries are also highly dependent on climate models, as we saw earlier - [the section on Wikipedia detailing various predicted Solar System habitable zones](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Solar_System_estimates) should convince you of this. Choices of the four constants for $S\_{eff}$, for instance, have *dramatic* effects on a planet, changing it from a Venusian hell to a cold Martian twin. Models from first-principles need to take into account, for instance, the greenhouse effect ([radiative forcing](https://en.wikipedia.org/wiki/Radiative_forcing), anyone?).
So, here's how to determine the habitable zone, in a nutshell:
1. Choose the properties of your star at a given time - essentially, luminosity.
2. Choose the physical properties of the sort of planet you want, early in its life. These include atmospheric composition, mass and radius (maybe), albedo, etc.
3. Create models of the evolution of the planet depending on the incident stellar flux.
4. Determine the range of fluxes in which such worlds can be habitable.
5. Calculate the radii at which the stellar flux will take these values.
All of this, for the best models, is extraordinarily complicated. I don't know how to do most of it. However, we can look at one type of case which is really simple: the [idealized greenhouse model](https://en.wikipedia.org/wiki/Idealized_greenhouse_model). A simple derivation can be found [here](http://acmg.seas.harvard.edu/people/faculty/djj/book/bookchap7.html).
Let $T\_s$ be the surface temperature and $T\_a$ be the atmospheric temperature (assuming that both are roughly uniform across the planet). The planet itself has albedo $A$, and its atmosphere has an absorption constant $f$, which depends on its composition. The incident flux is $F\_s$. The energy balance equation for the planet is
$$\frac{F\_s(1-A)}{4}=(1-f)\sigma T\_s^4+f\sigma T\_a^4\tag{Planet}$$
The equation for the atmosphere is
$$f\sigma T\_s^4=2f\sigma T\_a^4\tag{Atmosphere}$$
Putting these two together yields
$$\frac{F\_s(1-A)}{4}=(1-f)\sigma T\_s^4+\frac{f}{2}\sigma T\_s^4=\left(1-\frac{f}{2}\right)\sigma T\_s^4$$
Rearranging, we get
$$T\_s=\left[\frac{F\_s(1-A)}{4\sigma\left(1-\frac{f}{2}\right)}\right]^{\frac{1}{4}}\quad\text{or}\quad F\_s=\frac{4\sigma T\_s^4\left(1-\frac{f}{2}\right)}{1-A}$$
The latter is probably more helpful to us if we want to find the boundaries of the habitable zone, although because it is so idealized, it still doesn't take into account more complicated effects like radiative forcing. I should also note that setting $f=0$ makes $T\_s$ simple the planet's [effective temperature](https://en.wikipedia.org/wiki/Effective_temperature). However, it is almost never true that $f=0$; on Earth, $f\simeq0.77$.
I suspect I may have gone into a little more detail than you needed. As I said at the beginning, you really only need those two equations to figure out the rough boundaries of the habitable zone. Still, I hope that the rest of this answer was a little - dare I make this pun - illuminating.
[Answer]
You have already the data you need - $L\_\odot$ . That is the star's *absolute luminosity*. At that point you can simply apply the square root formula.
The habitable zone goes from $\sqrt{\frac{L\_\odot}{1.1}}$ to $\sqrt{\frac{L\_\odot}{0.53}}$.
In your case that is $\sqrt{\frac{1.05}{1.1}} = 0.977$ AU to $\sqrt{\frac{1.05}{0.53}} = 1.41$ AU.
There is also [this calculator](http://depts.washington.edu/naivpl/sites/default/files/hz.shtml) where you can plug your data and it will give 0.974 AU for the minimum habitable zone (runaway greenhouse) limit, and 1.717 AU for the maximum habitable zone limit. Optimistic habitability goes from 0.769 ("Recent Venus limit") to 1.809 ("Early Mars limit").
[Answer]
First, some basics. Luminosity and Power are the same thing. They are both energy over time.
The intensity of light is given by
$$\text{Intensity}=\frac{\text{Luminosity}}{\text{Area}}$$
The area in question is the area of a sphere (the power is being spread out over bigger and bigger spheres as the distance from the star increases).
$$A\_{\text{sphere}}=4 \pi r^2$$
So
$$\text{Intensity}=\frac{\text{Luminosity}}{4 \pi \* \text{radius}^2} $$
or
$$I=\frac{L}{4 \pi r^2} $$
If we are comparing two situations where we want the intensity to be the same, the we have,
$$I\_1=I\_2$$
$$\frac{L\_1}{4 \pi r\_1^2}=\frac{L\_2}{4 \pi r\_2^2}$$
or, more simply
$$\frac{L\_1}{r\_1^2}=\frac{L\_2}{r\_2^2}$$
Solving for $r\_2$, we get
$$r\_2=r\_1 \sqrt{\frac{L\_2}{L\_1}}$$
Now we plug in the orbital radius of the Earth and the Luminosity of the Sun (in those base units) and we get.
$$r=r\_{\text{Earth}} \sqrt{ \frac{L}{L\_{\text{Sun}}}}$$
$$r=r\_{\text{Earth}} \sqrt{ \frac{1.05 L\_{\text{Sun}}}{L\_{\text{Sun}}}} $$
$$r =\sqrt{1.05} r\_{\text{Earth}}\approx 1.02 r\_{\text{Earth}}$$
Similarly, the habitable zone pretty close to the one in our solar system, just 2% bigger.
[Answer]
This star is only slightly more massive/luminous than The Sun so expect the habitable zone to be extremely similar to The Sun's, for The Sun it is considered to stretch from 0.7 AU to 1.5 AU, although if a planet has thin atmosphere the inner zone could be 0.5 AU for surface water, and if a planet has a very strong greenhouse effect it could have liquid water past 2.00 AU. If you want a planet like Earth with a similar atmospheric pressure I would suggest moving it out a little further than 1.00 AU, between 1.08 and 1.15 AU sound about right to compensate for the slightly higher luminosity.
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Supposing you are trying to colonise planet that has no life what-so-ever but is otherwise an earth analogue.
First thing that I realised is that there would be no oil. So they would need to make bioplastic (assuming they could introduce plants to the inorganic dusty soil).
Then I thought that they could make cement from lime stone, but upon further research I realised that lime-stone is a product of coral and skeletal fragments.
This really got me thinking about how many useful materials are actually the product of living organisms.
**Other than metal ores, what useful construction materials exist in the absence of life? What compounds can you synthesise from inorganic rock?**
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# Silicon
Silicon is *everywhere*. The rocks are made of it; so is sand, and so would the regolith of your not-at-all Earthlike planet. Silicon bonded with oxygen and metals gets you silicates, which we commonly call "stone" - one of the most common building materials in the world. Silicon bonded with just oxygen makes silicone, and silicone can be used in place of plastics and rubber. Build your structures out of stone with silicone mortar, and you'll be in good shape.
# Carbon
Without life, there's still going to be plenty of carbon around, it's just going to be bound up in rocks and carbon dioxide. You're already breaking up rocks to make your silicone, so you can pull carbon out of them at the same time. You can also break up carbon dioxide in the atmosphere to get carbon and oxygen. This deals with your oil shortage quite effectively - we already have the technology to make plastics from atmospheric CO2.
# Gypsum
The reason limestone is used to make cement is simply that it's a very common form of calcium carbonate, but it's not the only such form. Gypsum is a common mineral form of calcium sulfate, very soft and easy to mine, and normally accessible near the surface, as it's a sedimentary mineral. You can also extract it from seawater, along with lots of other goodies like sodium.
[Answer]
# Earth was once like that
Do recall that every atom on Earth originate either from the Big Bang (Hydrogen, some Helium) or the fiery fusion furnace that is the center of a star, which then got thrown out into the universe from the massive force of a super nova (everything else).
This was then collected into a swirling ball of hot gas, which then became a molten ball of lava, which - for the most part - it still is, it just so happens the surface has cooled enough so that life as we know it have formed and started using the stuff that was on it.
This means that life is not necessary to create all the things that you need. Life has for instance not created the Calcium that you find in limestone deposits, it was already there. Life just accumulated it for you.
# You can synthesize "everything", with enough energy
I put "everything" in quotes because there are **some** complex substances that we humans have not yet perfected creating. But for all the simple stuff, like Calcium Carbonate and Calcium Silicates that you need for making cement, you can synthesize, as long as you just have an abundance of energy.
So you bring your reactor, either plain old fission reactor running on Uranium or Thorium or discarded Plutonium, or a handy little fusion ditto like a [Polywell running on Boron and Hydrogen](https://en.wikipedia.org/wiki/Polywell). These are the first thing you then mine: fuel for your reactor.
Next up you want to sustain yourself. For that you need water, air and fertilizer. Using the energy from your handy reactor you [reduce](https://en.wikipedia.org/wiki/Redox) minerals to extract Oxygen, Nitrogen, Hydrogen, Phosphorous and Carbon Dioxide. From this you start your [hydroponics](https://en.wikipedia.org/wiki/Hydroponics). Then, using the plant matter from these, and the load of useful [soil bacteria](https://en.wikipedia.org/wiki/Soil_biology) you brought along, you can start making real soil.
In the mean time you are also busy extracting all sorts of primary materials, Silicates, Calcium, Iron, Aluminium and so on, to be used for construction materials.
I am not saying this will be easy or efficient, but if you just hand-wave away the difficulties in producing energy — by for instance assuming that fusion is viable and works as well as we hope it will — then you will have all the starting material you need to get going.
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There's a good reason a lot of useful materials are formed from life - life collects energy and stores it in its biomass, which means that energy can be utilized later. As a result, it is unlikely that you would find a substitute for oil on a lifeless world, although there are some unconfirmed theories that oil generation may be possible without life.
Tectonically active planets may have usable geothermal energy sources that can be used for powering fuel cells, although it probably wouldn't be a useful export, since if you're in space already it's much more practical to generate energy from sunlight than go all the way down into the gravity well of a planet and carry fuel cells away from it. It could be useful for powering other operations on the planet though.
The main useful materials on rocky planets are raw materials like metals and minerals, and radioactive elements for nuclear fuel. Gas giants have an abundance of hydrogen and helium, which would be be important for fusion reactors or any number of future technologies. Helium may also be mined from rocky planets if scooping it from gas giants is impractical for some reason.
It is worth noting that for metals at least, asteroid mining would be more practical than planet mining since you don't have a huge gravity well to lug all that mass away from. However, asteroids aren't that big, and if you have an abundance of energy and a shortage of matter for big projects, planetary mining may be worthwhile.
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A ideal sized planet with an insulating atmosphere, liquid water and in the Goldilocks orbiting zone is about as ideal for terraforming as you can really hope to find (earth analogue goes a long way). It will take time and effort, but you've already gone to the effort of getting there.
Terraforming is a long term investment a you might get a spare planet out of it. You also have a planet where you can dump all the waste you like. Whats the worst that could happen? A ecosystem emerging?
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Natural **Helium** is most commonly the result of radioactive decay of several naturally occurring radioactive elements like uranium and thorium. Yes, it is possible that a future society could produce the gas via fusion reactors, but today, helium is a rather expensive and rare gas.
Additionally, rarer forms of Helium like the isotope Helium-3 can be found on "lifeless rocks" and could actually be valuable enough *today* to warrant [mining it on the Moon](https://en.wikipedia.org/wiki/Helium-3#Extraterrestrial_mining). It is potentially extremely valuable in energy creation as nuclear fuel.
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## Let's talk about the visible light "rainbow"
**In almost all** depictions of the electromagnetic spectrum, visible light is shown as a rainbow, and adjacent parts of the spectrum are monotone in color - there is no UV or infrared rainbow to be seen.
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[](https://i.stack.imgur.com/ifKTg.png)
**This is justified** - the vast majority of people (animals are a different story) are confined to visible light, so we cannot simply "explain" what an unseeable color looks like. Therefore, it's easiest to assume every wave longer than visible light is representable by "red" and shorter by "violet". **We can't color with unseeable colors, so we don't make more rainbows.**
In the context of fictional creatures evolving to see different parts of the spectrum ([let's ignore the challenges with that for now](https://worldbuilding.stackexchange.com/questions/20461/could-aliens-see-in-other-wavelengths)), can we identify groups of fairly similar waves - the "rainbows" for UV, infrared, etc. to determine the "colors" these creatures might see - or is there really just monotoneness?
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*Not a duplicate of [Colors of Things Outside the Spectrum](https://worldbuilding.stackexchange.com/questions/29645/colors-of-things-outside-the-spectrum) which asks what humans would see if light were absorbed in a specific way, instead of what other organisms would see if absorption remained generally the same as it does now.*
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There are no "similar waves" we just see the three base colors (RGB) becasue we have three types of color receptors. We have receptors for three, many other mammals have two base color, birds and reptiles see four base colors, some arthropods have a dozen. the number of different types of photoreceptors in the eye determine the number of colors you see, not anything about the light. organisms can have more base colors and will literally see more colors in the same stretch of the spectrum we see. The opposite is true as well red and orange are the same color to dogs just as there are several colors inside green to things that have multiple different types of "green" photoreceptors.
Colors are not created by light they are created by how our eyes sense light. Distinct colors will exist everywhere on the spectrum for eyes that can see them. The rainbow never stops just our ability to see it. There are more diverse rainbows inside out rainbow that we can not see. We are all almost completely colorblind, even with the narrow visible spectrum we can't see most of the colors.
[](https://i.stack.imgur.com/Af8Vw.jpg)
[Answer]
## Tetrachromacy
[Tetrachromacy](https://en.wikipedia.org/wiki/Tetrachromacy) is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cells in the eye. Most people have three cones (making them [trichromats](https://en.wikipedia.org/wiki/Trichromacy)), which enables them to see about one million colors. But tertachromats have four cones, so their eyes are capable of picking up dimensions and nuances of color-an estimated 100 million of them—that the average person cannot.
Humans are usually trichromats, but [recent studies](https://en.wikipedia.org/wiki/Tetrachromacy#Humans) suggested that 2–3% of the world's women might have the type of fourth cone whose sensitivity peak is between the standard red and green cones, giving, theoretically, a significant increase in color differentiation. Another study suggests that as many as 50% of women and 8% of men may have four photopigments and corresponding increased chromatic discrimination compared to trichromats.
## Concetta Antico
[Concetta Antico](http://www.popsci.com/article/science/woman-sees-100-times-more-colors-average-person) is a tetrachromat and so is able to see 100 times more colors than the average person:
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> When Concetta Antico looks at a leaf, she sees much more than just green. “Around the edge I’ll see orange or red or purple in the shadow; you might see dark green but I’ll see violet, turquoise, blue,” she said. “It’s like a mosaic of color. It’s shocking to me how little color people are seeing,” she said.
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## Same Neurology as Trichromats
Interestingly, although tetrachromats have more receptors in their eyes, their brains are wired the same way as a person with normal vision. So how can a brain like Antico’s change to see more colors? Like anything else, practice makes perfect, even when it comes to neural pathways.
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> Researchers Jameson and Winkler are on the hunt for more tetrachromats in order to better understand how their brains work. Jameson became fascinated with how people are able to form and communicate concepts, especially when the way they perceive the world can vary so widely. “If you have an extra cone class in the retina, that greatly complicates how that signal might be taking shape as it leaves the retina. We want to understand how that’s happening,” she said. This likely has to do with how the brain wires itself when it receives certain signals frequently over time—a concept called [neuroplasticity](https://blogs.scientificamerican.com/talking-back/new-clues-to-just-how-much-the-adult-brain-can-change/). Lots of studies about neuroplasticity in animals and some in humans have shown that two individuals with the same capacity for visual perception can have drastically different vision later in life just based on what they were exposed to early on. Researchers still aren’t totally sure why this is the case. “One possibility is that the system learns how to use these signals—the wiring creates the proper code so they can be used in the cortex,” Jameson said.
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>
> So even though many more tetrachromats may exist in the world, they may not have exceptional color perception, because they haven’t trained their brains to pay attention. Antico, in this case, presents a rare exception. “I was different than a regular 5-year-old — I was painting at age 7, I was so fascinated with color,” she said. For years, she was exposed to exceptional color, so her brain became wired to take advantage of her tetrachromacy.
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[Answer]
Assigning color names to certain wavelengths really is a completely arbitrary process and can be quite different in different cultures around the world. A very common example are languages that don't distinguish between green and blue, but there are many other variants.
The seven rainbow colors are just as arbitrary and you could very well say that it has only five colors: Red, organge, yellow, green, and blue. Whether you want to call light blue "indigo" and deep blue "violet" (there is no purple in the light spectrum) has nothing to do with specific wave length.
Creatures with eyes that are sensitve to different wavelength than humans would be able to distinguish between them just as well as humans do with red, green, and blue, and most likely also have the ability to see combinations of different wavelength (like we see orange).
The image in the question is actually wrong: The color spectrum it shows has all the infrared frequencies in red and the ultraviolet frequencies in shades of purple. In reality these would be just black to human eyes.
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Far in the future, I have a bomb about to detonate in the skies above my city, a real city/province killer. A hero dramatically manages to enclose the bomb at the moment of detonation in a living crystalline metal matrix, saving the city...or maybe only part of the city, I haven't figured that out yet.
The heat, energies, shockwaves, radiation, everything (I think) are reflected on one another by the crystal metal. Like a hall of mirrors reflecting your image back on one another indefinitely. The detonation is contained and compressed inside this living crystal metal resulting in a small glowing crystal artifact or cocoon (yes, this will increase the yield of the explosion IF it does ever manage to finish exploding).
Having watched way too much *Doctor Who*, I have imagined something that **looks like** a 'White-Point Star Diamond' but with none of the dimensional time lock/link characteristics. Just literally an explosion contained in a crystal cocoon. [](https://i.stack.imgur.com/tuwJI.jpg)
**'Normal' physics applies, no magic. Which is why I used the science-based tag. The only thing 'strange' in this story-world is the living crystal metal (that also does have *some* quantum entanglement issues, i.e, spooky action at a distance)**
* the living crystal metal is an alien symbiotic substance that will form an exceptionally strong (and malleable, not brittle) reflective cocoon around the explosion.
* the living crystal metal shape can only be destroyed by; the person who created it willing it to cease, the creator dying, being struck multiple times by another living crystal metal item, or a massive amount of energy (i.e the bomb blast itself, may wear down the crystal metal from the inside)
+ to prevent accidental release of all the pent up energy, several individual's add several buffer layers of living crystal metal around the Cocoon - even if the explosion does break through one bond, there are still several more layers before the big badda boom.
First off, bearing in mind Far-future and advanced phlebotinum, **What sort of explosion definitely would/wouldn't work in this situation?**
The bomb makers have a tendency to base their weapons on light but this particular bomb could always be new/old tech, so anything I should be aware of?
I imagine that with time the potential energy of the bomb will increase exponentially by being contained in a reflective substance. I have several ideas to help with this but am not sure which would actually help the most or do harm.
* constant 'feeding' of the crystal metal to replenish cocoon strength, or
* periodic 'feeding' of the crystal metal to replenish cocoon strength,
* occasional release of the pent up energy (this could be dangerous, and dramatic),
* the energy from the explosion actually provides the energy to maintain the cocoon rather than wear it down?
Secondly **How will the energy from the explosion react to being constrained by a reflective surface?**
and Thirdly (BONUS) **How will the energy from the explosion react IF it were to be suddenly released?** I'm thinking 'end of the world...'. How bad are we talking?
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Energy is an odd concept. By the current known laws of physics, energy cannot be created nor destroyed. However, "useful" energy can be destroyed by reducing it to thermal energy. Thermal energy is no different than any other form of energy, except that it is so unstructured that it tends to behave in very statistically boring ways. To make your story interesting, we're going to have to dig into some physics first. Bear with me.
When we start to look at bombs, it's important to understand stability and metastability. A material is "stable" when its energy is at its lowest. A rock is pretty darn "stable" by this definition. We can contrast this with an unstable material, which is at an elevated energy state. The flame burning around a candle is unstable. It must constantly tumble towards a lower energy state, and if it wants to remain around for a long period of time, it must find a fuel source. In the case of a candle, this fuel source is the vaporizing wax emitted from the wick. As long as there's wax to burn, the flame can stay. However, once there's no more fuel, it snuffs itself out.
Metastability is a strange hybrid of the two. A metastable compound is mostly stable, but can be pushed into a unstable regime. Consider a cup on a table next to your favorite feline. The cup is rather stable. It's not going anywhere; the table is flat and solid. However, if the cat merely nudges the cup in the wrong direction (and they *only* nudge them in the wrong direction), the cup will become unstable, fall to the ground, and break.
Explosives are like that. They are metastable. They are designed to be very stable while working with them, and remain stable until an initiator sets them off. At that time, they become unstable and... well... blow up.
So, with those scientific terms covered, let's get back to your story. It *is* reasonable to contain an explosion inside a container. On one of the recent nuclear tests done by North Korea, they contained their bomb underground. There's no exponential power gains or anything like that. Being contained simply means that the container has to dissipate the energy. The ground is very good at...well... not moving very much. It happily contained that nuclear explosion. Of course, the energy has to go somewhere. Some of it went into heating the ground locally. Other portions of the energy were turned into seismic waves which echoed around the world. This was actually what the western world used to validate North Korea's claims about the test. We looked at the seismic waves and compared them to what we expected to see given their announced data!
Now there's something interesting about these two ways of dissipating energy. Thermal energy is highly random, and generally uncontrolled. The nature of the seismic energy, on the other hand, is highly structured. It's structured enough that we can detect it on the other side of the world and make inferences. Its structure is based on the materials of the earth. Some frequencies naturally translate well, and some do not. For example, typically high frequencies attenuate quickly and lower frequencies do not. That's why shutting the door on your brother's loud music blots out the high parts, but the low bass rumbles through the door. Your door is transmitting the low frequency sounds, but its turning the high frequency sounds into heat. (You just don't notice the heat because it's *tiny* in the case of audio energy... but it is there).
Now one solution is to have the crystal simply convert everything to heat. This is easy -- because the bomb already wants to heat things up. You don't have to do anything special. All you have to do is have the structural integrity to not blow up under the intense pipe-bomb style pressures that the bomb will generate. Once you're done holding the bomb in, you're going to have a *very* hot inner surface. That heat will then propagate outward towards the outer surface. The crystal can then simply "cool off" for a while, dissipating all of that heat energy.
How much heat energy is it going to have to deal with? It turns out not very much. As I pointed out in comments, bombs don't depend on massive amounts of energy. They depend on sudden localized impulses. The sun puts *far* more energy on the earth every second than your city-killer would ever emit. For a real life data point I love to turn to Wikipedia's page [Orders of Magnitude (Energy)](https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)) and find interesting coincidences. Today's coincidence: Little Boy (the bomb we dropped on Hiroshima) outputted $6.3\cdot 10^{13}J$. That's the amount of solar energy that falls on Costa Rica in a single second! The amount of energy in these sorts of weapons is nothing compared to what our planet experiences every day from the sun!
Now this isn't quite the ringing crystal effect you are looking for. If we did everything with thermal energy, your crystal would be done with its job in days (weeks at most), and once it was done with the few few seconds of the job, we could all be pretty confident that the risk is over. You want a bit more thrill. For that, we're going to need to harness the energy of the weapon, similar to the seismic waves through the earth.
The big difference between this case and the thermal case is that, in this case, we want to capture all of that energy as potential energy. Eventually, we want to re-emit that energy *slowly* to dissipate it. Think of your crystal metal kinda like a tuning fork. The bomb gives it a really *really* hard thump. It elastically responds, and then springs back into a vibrating state that we use to tune a piano. In this case, much of the energy of the original explosion remains pent up inside the structure of your crystal/tuning fork. If you want to see how much energy is in one of those tuning forks, give one a rap and then hold it up to your teeth. Like your crystal, tuning forks have a lot of energy that you don't want going in the wrong directions!
Now in a realistic setting, the energy dissipates. It'd be very loud, but doable. You'd probably want to structure the crystal metal such that the outside is a "node" for the sound, meaning none of the energy actually escapes. In this case, you'd simply find the crystal metal flexes back and forth until that movement eventually turns all of the energy to heat (like before). This is getting closer, but we still don't have too much thrill. Again, it would be easy enough to dissipate most of the energy fast enough to be boring. We need something to make it more interesting.
What if the weapon that was set off was a new weapon, and there was a pressing need to understand it better. In such a case, there would be a strong desire to not destroy any information you have about the weapon, and turning meaningful energy into heat energy destroys information. There might be a desire to *intentionally* keep all of the energy pent up. In such a case, your magical crystal metal might try to hold onto as much of the information from the blast without destroying anything. Naturally, this would require keeping all of that energy pent up while the powers at be decide what to do with it.
Remember the earlier topic of metastability? Your crystal just became metastable. In theory, it is perfectly containing the energy of the explosion inside of its structure. However, if mishandled, it may cease to be able to contain that energy, and unleash it as though it was an explosive itself!
In this case, the destruction of the crystal metal would never exceed the original explosion, but it would keep the threat looming for as long as your magical metal can avoid turning those sound waves to heat. It would encourage "care and feeding" to help it maintain the constantly shifting effects.
[Answer]
Now, How does an explosion work? It has mainly 2 foundations:
1. setting free thermal energy by destroying covalent bonds
2. changing the state of the solid explosive to expanding gas
As it does both, the result is a shock wave, which in turn is what destroys items.
The basic physics behind stable, unstable and metastable objects was very well explained by [Cort Ammon](https://worldbuilding.stackexchange.com/a/60658/25822), but he did not look into the gas part too much.
## Thermodynamics of explosions
Now, let's take our metastable compound, for example [2-Methyl-1,3,5-trinitrobenzene](https://en.wikipedia.org/wiki/Trinitrotoluene). We know very well about the behavior of this when it becomes unstable, and we know pretty well that it produces a "[standard gas volume](https://en.wikipedia.org/wiki/Explosive_material#Volume_of_products_of_explosion)" of $975 \frac l{kg}$. So if we just convert 1 kg of TNT to gas at standard conditions (20°C, 1 atm, V=22.5 l/mol) the gas formula $pV=nRT$ will give us a V of 975 liters, or in reverse, the correct number of molecules n.
Now, our TNT doesn't turn gas in an instant, it doesn't turn so at 20°C either, something has to happen: first of all, the reaction takes time and starts somewhere. Then the block "burns through" with a [speed](https://en.wikipedia.org/wiki/Explosive_material#Velocity_of_detonation) of $6900 \frac ms$ from our initial detonator to the edges, so it is finished within a really tiny fraction of a second. Doing so, it sets free a lot of heat $(3725 - 3612 \frac{kJ}{kg})$ and the kown ammount of gas molecules n (which is not a number that is really well to handle, let's keep it that way).
Now, we have our formula above, we know standard condition volume and pressure, so we can recalculate with our known n... Obviously we stumble about a factor that isn't the same as before: T aka temperature has increased by those more than 3600 kJ for 1 kg. We have a temperature of at least 300°C now and maybe much more, so our gas will have to do something to compensate for the increased T as n will stay the same. The first step any gas does to compensate increased temperature is always the same: it expands, increasing the V part of the term.
Once it can't expand freely anymore (because there is something like solid objects or other gases in the way), it will start to put itself and the 'barrier' under pressure and increases the p part too (actually, it starts so the very moment V increases, but not so fast as it will once hitting solid object). This puts stress on the objects it hits, creating a shockwave.
Luckily for us, the art of blowing up things provides us with an indicator how strong this shockwave is via the [Trauzl test](https://en.wikipedia.org/wiki/Trauzl_lead_block_test): TNT creates a cavity of $30 \frac {cm^3} g$, so our 1 kg block above makes a cavity of 30000 cm³, or about 30 liters, in a similar lead cylinder. Compressing 975 liters to a 30 liters cavity is a factor of 32.5, so we have a pressure of roughly 32.5 atmospheres.
That is our shockfront: 32.5 atm or 477.6 psi (under ignorance of the thermal factor again) at the very end of the expansion (in the lead block), and much more in some of the steps to get there.
## What does this tell us about our 'container'?
### Stress on the Crystal
Now, our crystalline structure will have not only to endure the thermal energy that was previously stored in the covalent bonds of the explosive, it also has to endure the pressure the expanding gas puts upon it. To do so, our structure is better highly ductile, allowing it to deform with the expanding shockwave and lessening the impact due to longer exposure time: Force is always mass times acceleration, and acceleration is speed change over time. or, as a formula: $\vec F = m \times \vec a = m \times \frac {\text d \vec v}{\text dt}$. Let's assume m (mass of crystal) and v (speed of the shockwave} are constant, then by taking 1 second instead of 0.1 second to stand in the way of the shockwave will put only 1/10th of the stress upon the crystal. So our "crystal" better be mallable to some degree to increase its potential at containing the explosion by expanding. Think about this like... a baloon or a tire.
### Path of least resistance
Now, we always assumed our crystal would have to contain the whole detonation. What if we only placed the barrier on one side, and kept open sky above or put the detonation between two crystal disks? Now we face very interesting effects: shockwaves and expanding gasses take the "way of least resistance". Partly this is because it is much "easier" to increase volume by applying pressure to push away gas than applying pressure to indent solids, partly this is because in indenting solids causes some of the particles that were sent against the solid are reflected. The result is pretty simple:
If you detonate something against a solid surface, and don't take care to apply pressure on it, you get a loud bang and a little bit scorched ground. Also, Detonation shockwaves don't get around barriers very well (they can, but it is more difficult). This is used as a trick to create directed charges: a strong barrier and a weak barrier encase an explosive, forcing the detonation to deform the weak barrier (usually copper) and turn it into a cutting edge.
## Solution
Should the bomb not contain harmful materials to the city underneeth it (nuclear devices, dirty bombs, chemical compounds), the way to go would not be encasing the bomb fully, but to encase the lower half of it. This will direct the shockwave upwards in a flat cone (or to make it mathematically correct: [spherical cone](http://mathworld.wolfram.com/SphericalCone.html)), minimize the stress on the crystal and at the same time maximise the protection. A detonation at the very 'horizon' of a half-sphere reflector will expand to the non-shielded half-sphere. If it detonates lower, the stress gets bigger, but the resulting effected cone is much more focussed.
[Answer]
Don't overthink this:
You basically just build a pipe-bomb; A explosion is just a sudden release of stuff (heat, air, radiation) into the surounding environment. If the "stuff" can't escape, it stays under pressure until the time the containment fails. Basically you just bottled the explosion, delaying it's effect.
This would work on anything we classicallly consider an explosion.
The explosion wouldn't get stronger, because you are not adding any additional energy, but it could potentially be more focused (e.g. when you contained all the energy of a aerated fuel explosion (meter wide dispersion of the explosion "fuel") into a few centimeters, the core of the explosion would of course be more energetic, even when releasing the same amount of explosive yield).
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What would be the impact on modern civilisation be if a benevolent inventor gave the world the ability to travel around the solar system quickly and cheaply.
If over the next five years this technology was built and tested by the likes of Space X and proven to work, meaning that with a powerplant the size of a small car, it became possible to transfer loads from the surface of one planet to any other in the solar system in a matter of days / weeks.
The technology is open sourced, relatively simple to build, even by technically proficient, moderately funded amateurs
## Limitations
For whatever technical limitation, the maximum carrying capacity of the powerplant is 50 tonnes. Including the vessel. It is not possible to use the powerplants as a group to improve that limit.
While it is clearly capable of impressive speed, it has a very limited range, which just happens to be about the size of the solar system. i.e. its thrust is time constrained, at maximum speed its fuel quickly degrades, meaning it wouldn't be able to stop if further travel were attempted
What are the economic, political and social changes that this technology would produce over the next ten years.
## Edit
The idea behind the weight limit is to make it akin to a small truck / coach. It could either move a bunch of stuff, or a bunch of people. But would make large scale mining operations etc less likely. There would also be a 'there and back' usability. So you could jump in your space craft on the back streets on Birmingham, take a trip to Neptune, and make it back home again.
[Answer]
The true limitation here isn't time or distance, but rather the amount of stuff you could carry. A 50 ton spacecraft isn't very big, and since this is the all up limit, including astronauts, life support and everything else, missions will be limited to whatever can be packed into a very small mass budget.
So the first thing this would drive is the quest to miniaturize everything. Closed Life Support Systems would have to be miniaturized so the astronauts are not stuffed into a capsule filled with plumbing, or constrained by having a train of other spacecraft following them full of MRE's and Oxygen bottles so they can actually carry out useful work once they reach their destination. This also would mean that they might be radiation limited, since radiation shielding is going to take a large amount of the mass budget. The book "The Millennial Project" suggests that a water shield 5 metres deep is required for long term passive shielding from cosmic and solar radiation. Active shielding might be possible using superconducting magnets, electrostatic shields or other exotic technologies, but even there the mass and need for a power plant is going to cut into the mass budget. We can go on about landers, rovers, robots and so on.
Economically, outside of the development of miniaturized technology, there will also be some strange economic bubbles. I am presuming this drive needs to be lofted into space first before being activated (this is unclear from your description), so rocket launch services will be a boom industry. Other support industries like long range space communications will benefit, and of course there will be a speculative boom as banks and financial institutions as well as Fintech (crowdfunding, direct loaning like the lending club) and the stock market are attracted to this sector.
Politically there are two different scenarios which might happen.
Governments and populations might become "fat and happy" with the flood of new revenues coming in (the first waves of people heading out will most likely be asteroid miners looking for a quick return on their investment). People who stay at home and cut coupons and collect dividends will enjoy their lives and decide those crazy space people are ok so long as they stay in space. Asteroid miners don't get invited to too many parties.
The other way this could go is the governments of Earth send their bureaucrats to set rules and regulations, and their police and armed forces to enforce these rules. This is both due to greed (they want 100% of these revenues) and for self preservation. A 50 ton asteroid moving at interplanetary velocity is a weapon of mass destruction. The Chelyabinsk meteor was fairly small as these things go and delivered an estimate 500Kt of energy when it disintegrated in the upper atmosphere. A modern strategic nuclear weapon is estimated to deliver @ 300 Kt, to give you some comparison, so governments will be nervous about having this much energy available to potentially disgruntled people out in space.
The regulatory strangulation route seems likely unless this development is either so cheap that Ted and Earl can build it in their barn out of discarded parts, and launch directly into space from the barn. The internet is a good illustration of a disruptive technology that managed to spread fast enough to evade being smothered by government regulation for the first several decades of its existence. Your 50 ton limit makes an internet like revolution unlikely, since people will firstly be overly dependent on technological developments specific to miniaturized space systems to function, and secondly the size of the ships will be too small for large expeditions to set up colonies to develop independent powers and new polities throughout the Solar System to counter the governments of Earth.
[Answer]
# Mining
See [Wikipedia article](https://en.wikipedia.org/wiki/Asteroid_mining), especially this part:
>
> Minerals and volatiles could be mined from an asteroid or spent comet then used in space for in-situ utilization (e.g. construction materials and rocket propellant) or taken back to Earth. These include gold, iridium, silver, osmium, palladium, platinum, rhenium, rhodium, ruthenium and tungsten for transport back to Earth; iron, cobalt, manganese, molybdenum, nickel, aluminium, and titanium for construction; water and oxygen to sustain astronauts; as well as hydrogen, ammonia, and oxygen for use as rocket propellant.
>
>
> **Due to the astronomically high costs of current space transportation**, extraction techniques still being developed and lingering uncertainties about target selection, terrestrial mining is currently the only means of raw mineral acquisition today.
>
>
>
Emphasis mine. It looks like you are removing only real obstacle.
# Industry
You can't pollute atmosphere on asteroids and moons there is none. If you can mine all you need, you can as well manufacture goods up there.
# Environment
Above points would make some major reasons of pollution void, so Earth would get cleaner, quieter place to live.
# Law
Space is under no-one's jurisdiction. This would open all kinds of hell. Worker's rights? Not there. Police? None. As soon as new bases are opened, lawyers will start battles that wouldn't be settled for decades, because corporate needs would be quite opposite to what politicians need to appear to be doing. Pretty much any outcome you want might happen.
# Spacers as sub-society
Not exactly, not at first. But space mining and industry would be lucrative. Some people would want or need to go for "just one more contract", stay "just a month longer", and some of them would be unable to go back to Earth. Families would get broken. Children born in space would be at strongest disadvantage. After some time of limited contact, Dirters and spacers would look at each others with distrust and lack of understanding. english will stay as common ground for communication, but we can expect Space english, just the way we have British and American one.
---
# Size
Lunar Module from Apollo missions was 15T. With crew, fuel and all. So your ship has a quite lot of margin. You don't need to send everything at once, you can send easy to assemble parts. Modern space stations are already made this way.
Of course high competition will lead to mass usage optimizations.
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I don't think you need to look to far into our past to see what would happen. Colonization, and political "stuff" would follow almost the same pattern.
Of special interest may be Central America. Keep in mind that colonization efforts of "the new world" had similar limitations. A ship big enough to cross the ocean could only carry so much.
A lot of your "human" responses will be the same. Colonization, reform, separation. I think things these days will go along the lines of Canada or Mexico and not the lines of the USA (A more peaceful resolution to the independence issue).
We have not changed so much that those models no longer apply. We have hopefully learned from the mistakes of our past, but that doesn't mean that the same patterns won't arise.
I would recommend focusing on Naval law and historic colonization patterns. Also keep in mind, that there needs to be a "reason" to go. Look at Mars. We have the tech and the means right now to go to Mars. What we don't have is a reason for the hardship it would cause. If they found some super profitable material on Mars you can rest assured that they would stuff astronauts into tin cans and launch them at the planet. Same way we did with the moon. You engine makes this more viable, there is a bigger tin can, and it doesn't take as long but we still need a reason.
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Others have provided great answers, but, in a nutshell, the economic, political and social changes would be very significant over the next 10 years.
We have a very recent and very pertinent example to guide us...**the Internet**! This technology is similar in importance to the intra-solar technology you are describing.
For all practical purposes, the Internet wasn't "on every desktop" until after 1994. Within the 10 years after 1994, planet Earth changed dramatically...socially, economically, politically. Earth was never the same because of the Internet. We are now, 22 years later, completely and hopelessly dependent upon the Internet.
In general, intra-solar travel would follow the same general pattern. Extra-Terra colonies would begin forming. New forms of trade would come to pass. We'd have access to new energy sources. Scientific opportunities would greatly increase. Ultimately, **I think it would have significantly more impact than the advent of the Internet**.
We...the bacteria...would have easy access to a much larger and richer petri dish!
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If a spacecraft with a maximum mass of 50 tons can take off from the back streets of Birmingham and fly to Neptune and come back it must be able to generate a rate of acceleration in excess of one g. This will enable it to travel anywhere in the solar system in days or up to weeks. The spaceship would take about a week to travel to Neptune at 1 g, and another week for the return trip.
This does suggest that the spaceship will reach a maximum velocity of one percent of lightspeed. To think people were worried about a fifty ton missile moving at 500 km/s, that's peanuts compared to the impact this baby would make.
It's hard to imagine a spacecraft drive power plant with an upper limit to its mass of fifty tons if it can generate an acceleration of 1 g plus. This takes us into realm of Aristotlean physics and that's only a more sophisticated version of magical thinking. The rest of this answer will assume, irrespective of the space drive's power plant, that Newtonian physics applies.
This will mean the mass limit is mirage, however, if the true limit of the space drive's power plant is the volume encompassed by the drive field then this argument collapses. Considering the possibilities of this kind of space drive in relation to Newtonian physics has some interesting results.
A larger version of this vehicle, with a payload of five hundred tons, could be supplied by a fleet of space trucks plying the Earth surface to orbit run, and launched with a modest acceleration of one-tenth g. This larger vessel would be slower and hopefully surer, but would the advantage of a heavier payload. This will make expansion into the solar system an easier proposition.
A further step of allowing for lower acceleration and a higher payload would be to go down to an acceleration of one-thousandth g or one centimetre per second squared. The payload is now fifty thousand tons and the solar system is our oyster!
While racketing around the solar system in a single fifty tonner spaceship might be fun, there's not too much they can do. However, if you start flying fleets of them travelling in squadrons or running regular routes so lots of spaceships are travelling to, say, Neptune in large numbers and at regular intervals. Many of these craft won't need to be manned. Now by allowing bigger, heavier and slower rates of acceleration this space drive will make human expansion into interplanetary space both rapid and easy.
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In movies, novels, fictions and mythologies, it is quite often told/seen/heard that the blood of the gods are that of gold.
I want to know how does gold colored blood works in biology, what are its chemical compositions, what makes it gold?
[Answer]
## [Coboglobin](https://en.wikipedia.org/wiki/Coboglobin)
Coboglobin is currently a synthetic protein that performs the same function as hemoglobin. It uses Cobalt in place of the iron atoms.
>
> Blood of this type would be **amber yellow** in color when in the veins
> while **uncoloured and clear** in the arteries.
>
>
>
Quoted from Jim2B on [Other blood colors](https://worldbuilding.stackexchange.com/questions/28276/other-blood-colors?rq=1)
This the closest thing I can remotely find that's even close to the color of gold. But I recommend giving up on a suitable answer cos it would take a alien creature or some other unknown substances to really make gold blood. Or you could take all that gold from Smaug, melt it and voila.
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According to [Wiki](https://en.wikipedia.org/wiki/Blood#Hemovanadin)...
>
> The blood of some species of ascidians and tunicates, also known as
> sea squirts, contains proteins called vanadins. These proteins are
> based on vanadium, and give the creatures a concentration of vanadium
> in their bodies 100 times higher than the surrounding sea water.
> Unlike hemocyanin and hemoglobin, hemovanadin is not an oxygen
> carrier. When exposed to oxygen, however, vanadins turn a mustard
> yellow.
>
>
>
[Answer]
The gods blood was nano gold, gold particles that are no bigger than a virus. We as humans have nano iron running through our blood as a conductant for electric pulses to run throughout our bodies to sustain our energy, life, soul etc. this is how touch screens on your smart phone or any other touch devices are able to work. However, nano gold is an EXTREME super conductant unlike iron. When you take a strand of iron wire and put an electrical current in one end you will only recieve a smaller percent of that current out of the other end. Where as if you had an abundancy of nano gold (good luck) to be able to strech out no matter the distance from one end to the other, when you put a certain amount of electric currents in one end of the nano gold, on the other end you will recieve 100% of that same current. The gods were immortal because of this, their bodies held perfect energy that would sustain life forever with nano gold blood. 100% in 100% out. Yes the gods did have gold blood, they figured it out why cant we? Everything makes more since with a little knowledge.
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While you could look at it from a literal aspect (the blood is colored like gold), you could also look at it as a metaphor. In real life, there is "Golden Blood". Rh[null] blood is so rare, less than 45 people in the world have it and it can be used as a true universal donor, even for the people that O- blood normally can't help. I know you wanted the literal side of things, but I was beaten to that answer, so I hope this makes for a nice second best!
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How is Charybdis from *The Odyssey* powered? As odd as it seems, I'm looking for a science-based answer.
* She needs energy. To suck down warships, she is at least 75 ft in diameter and must suck them *at least* 15 ft down (probably more). That column of water weighs 2050 tons (and that's a low-end estimate). To raise it back up from where Charybdis is holding it (she spits it back out again). is going to mean lifting 2000+ tons 15+ feet. By my calculations, that's about 20,000 Cal/lift, at 100% efficiency. 3 times a day.
* She's not eating people: ships rarely sail through the strait and those that do stay near Scylla, so she can't possibly be sitting around sucking water 3 times a day for those few occasions when ships do come by.
* She's not eating wood, either: she spits out broken bits of Odysseus's ship and he grabs a part to paddle out of there.
* It seems difficult to believe that she could be filter feeding plankton (or other stuff): she doesn't move and would quickly deplete plankton stocks in her vicinity. Also, her energy consumption of 60,000 Cal is much more than other filter feeders.
* She's not tidally powered: she is on a 3 cycles/day timer and tides are roughly 2 times/day.
My current best guess is nuclear: she's filtering out deuterium and fusing it for energy, however this seems a little far-fetched.
Note: I couldn't figure out what tags would work for this question, so please edit and add/remove them if needed.
[Answer]
The raw power is provided by a geothermal vent. It is a tool built as a trap by a particular clan of smart cephalopods. That's why it is a singular monster and not a species to be found as a hazard everywhere!
What would normally be a hot spring (note the presence of volcanic activity in the Mediterranean in general) is a chamber some distance below the sea floor that would normally fill with water through various seepings and plumbing with other vents, with the resulting hot water flowing from a major opening at the top of the chamber. What makes one of these a [geyser](https://en.wikipedia.org/wiki/Geyser) is how the chamber and plumbing glaze over with mineral scale making a waterproof pot, and inflow is limited. It fills, and when it reaches a boil the steam explosion drives it out the top vent.
This is tamed and modified slightly so as to be controlled by the animals. Only a small inflow is allowed, and the top vent blocked. The chamber is air filled with just a little water simmering at the bottom, the whole thing being carefully tended to keep it stable in this configuration.
When large prey passes through the channel, directly over the top vent, the lid is released. Perhaps it is a mud/stone flap that is single use; crack it and *whoosh!* the swimming prey is dropped into the hot cave. A surface ship is damaged when the water around it is dropped, as it is then hit by 30-foot waves from all sides that rush in to fill the sudden void.
The secondary vents are then blocked and the water-filled chamber allowed to act as a geyser in normal fashion. This empties the chamber providing now-dead and cooked prey many times larger than the animals that trapped it. As the geyser is petering out a fresh lid is set in place and when the pressure drops it is drawn tightly into place, resetting the trap.
It takes a few hours to cycle, and the trap owners like to eat regularly. Thus, they tend to lure large preditors to their trap as often as they can spring it, which is about three time a day. The accounts don't notice or make note of the huge shark or octopus that was *flushed*, as it was underwater to begin with. The reporters are focused on ships.
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Sorry, I'm not very current on that particular myth, but could she be an enormous plant?
Maybe the land on either side of the straight is actually part of her body. Two enormous bulges which rise up out of the water in what was once a much wider channel. With the two halves of her body taking up most of the natural channel's opening, all that is left for hapless sailors is the narrow straight in-between.
If that kind of a design is okay with you, then both of her body bulges could be covered in leaves, soaking up sunshine to fuel her water exercises.
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The legend of Charybdis is generally considered to be based on a naturally-occurring tidal whirlpool in the Strait of Messina (one of the rock formations nearby is thought to be the origin of Scylla). There are many other whirlpools such as these which form in narrow straits and are powered by the tides, forming on schedule several times per day.
Perhaps the creature Charybdis does not *create* the whirlpool, but rather *exploits* it - a large, generally stationary sea monster that rests at the bottom of straits with its mouth open, eating fish and plankton that are sucked into the maelstrom. This would not get it as much food as hunting, but since it spends nearly all of its time dormant it doesn't really need much.
The number of times a day a whirlpool forms varies from one instance to another, but is generally either two or four. Maybe you could say they form three times a day *on average*?
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**Here is the massive physics problem with Charybdis**
Where does the water go? and how can it move enough water to make a vortex?
One thought would be it has a big stomach that its pumping water out of till it opens its mouth sucking in everything above. This has a ton of problems like how does it remain submerged with such a huge bubble, how can it resist the pressure of the ocean around it trying to collapse its bubble. The sheer forces here stretch thin the limits of biologic possibility. Not to mention the energy needed to pump all that water out and create a bubble.
**My thought which sounds more plausible to me** is that its more **like a giant worm/snake/tube**. Instead of creating a bubble and resisting all those pressures perhaps it works more **like an intestine**. Using its muscles to constrict force water from one end to another. That way the pressure inside and out are relatively the same.
It would need to be long, many times longer than it is wide. Its skin would be thick to house the muscles necessary to constrict and expand. It length would also be dependent on how its able to digest what its sucked in.
Also, I don't think it would poop per se. I think its back end would be an open hole constantly excreting water similar in diameter to its mouth.
As a fun thought, it could be that it doesn't intentionally pray upon ships and large fish. It could be a large filter feeder primarily trying to eat algae and plankton and just so happens to get other creatures by chance.
The jagged rocks described at its mouth could be teeth and it could have teeth like structures lining the first part of its inner body to break up large debris entering it. Its lower body would probably have more mesh like structures to more easily extract nutrients.
A [Pyrosome](https://en.wikipedia.org/wiki/Pyrosome) is semi relevant in that they are big floating tubes that can suck in water filter it and push it out.
[](https://i.stack.imgur.com/DLDWp.jpg)
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If there were a sphere or a cube where time is stopped, how would someone passing by perceive that? I have something in mind that stops everything, including air and light, not only solid matter.
My first thought was, if nothing comes out it must be pitch black. But that would lead to this region building up enormous amount of energy over time, absorbing all light. When the time starts moving again I think this would result in some kind of huge catastrophe eliminating everything inside the area (and probably outside too).
Not only when time stops there should be no change at all. So no energy build up. But also it would be inconvenient for the plot ;)
But if it can't be black, how should it look? *Bonus points for how it would feel to touch it.*
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If nothing, neither light nor matter, can interact with the region, I see three possibilities:
* total [specular reflection](https://en.wikipedia.org/wiki/Specular_reflection)
+ The region acts as a perfect mirror at all wavelengths. It looks like a shiny silver sphere or cube.
+ The surface feels warm to the touch, since you feel your own warmth reflected back at you
+ The region feels perfectly smooth and rigid.
+ Either it acts like an absolutely immobile object, anchored to some point in space; or you can move the whole region with enough force, but only as a block.
+ If the region has sharp corners or edges, they will indeed be very sharp. Even the 90° angles of a cube could be dangerous.
* total [diffuse reflection](https://en.wikipedia.org/wiki/Diffuse_reflection)
+ the region reflects light of all wavelengths, but the reflected direction is random. It looks like a white sphere or cube.
+ the surface appears to be a perfect white. In the shadow it will appear darker; under a green light it will have a green tint, and so on.
+ Interaction with matter will be similar to the specular reflection case
* invisible and intangible
+ the region does not interact with light and matter at all, everything simply passes trough, or spacetime bends around it.
+ not very interesting, for all intents and purposes the region has simply disappeared
Use in literature:
* Vernor Vinge uses regions of stopped time in his books "[The Peace War](https://en.wikipedia.org/wiki/The_Peace_War)" and "[Marroned in Realtime](https://en.wikipedia.org/wiki/Marooned_in_Realtime)", which I heartily recommend. Scientists invent a device which can create a "bobble", a spherical region in which time has stopped.
One interesting consequence he mentions is the buoyancy of such a bobble. A bobble that contains mostly air has almost the same density as air. If the region of stopped time is not anchored to anything, it may rise and sink in the atmosphere, as the surrounding air gets warmer or cooler.
* Larry Niven has a similar device in his "[Known Space](https://en.wikipedia.org/wiki/Known_Space)" series, the slaver stasis field. The region appears silver and smooth to the touch as well.
Some notes on the possible physical problems:
* A perfectly rigid object is not allowed in general relativity; it would allow faster-than-light communication: push one side, and the other side is immediately pushed by the same amount.
* an object anchored to some point in space is likewise problematic under relativity, since there is no absolute reference frame to decide where that point is. (This is not a problem if the region is not anchored to anything)
Some handwaving may be required to explain these contradictions.
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In my setting I have what is essentially air filled, zero gravity, space with floating islands scattered all over the place in a large, three dimensional cluster. What I'm wondering is how the skyship captains and others would be able to tell directions as there is no north-south axis and up and down are relative. In answer to David K I'm looking more for what directions to give to the helmsman then map coordinates
**Edit:** There is illumination, all islands glow to one degree or another; the islands are of varying shapes and sizes, some have relative tops and bottoms, others are more spherical; The islands have local gravity of varying strengths depending partially on island size; The islands drift based on strong storms, proximity of other large islands, and the movements of the "heart" of the cluster, basically a really big chunk of magic coral that produces gravity (oversimplification); This is in a fantasy universe, there is air throughout. It gets thinner and colder the farther away from any island you go. There are magics that can hold air at a specific pressure in a small area though so thinner air is only an issue if you get swept off your skyship.
[Answer]
The environment you describe removes key problems that drove
the development of navigational technology on the Earth,
and introduces new problems (including some that are not obvious)
in their place.
## **The effect of a horizon**
One reason (perhaps *the* big reason) why it's so often so difficult
to find your way over long distances at sea
is that the Earth itself gets in the way.
If you want to go somewhere more than a few dozen miles off-shore
you need to have a good way to tell that you're going in the right direction
without being able to see either your destination or any other landmark.
With your floating islands, this problem disappears.
Everything is in line of sight
(unless another island is directly in the path, in which case you would want to head to that island first).
## **Finding your way in the dark**
On the Earth, it gets a lot darker at night than during the day,
and things that could have been landmarks are no longer visible.
On the other hand, you can see the stars at night.
Navigators on Earth learned to navigate by whatever kinds of things
they could see, which vary from time to time.
In your cluster, there does not appear to be any reason for things
to be more or less visible at different times.
## **The Earth's axis of rotation**
The fact that the Earth rotates and that we can therefore see the apparent
motion of several prominent objects (notably the Sun!) from east to west
gives some obvious, natural directions for navigation.
OK, you've taken this away, which introduces an obvious problem,
but perhaps relatively minor compared to the next one.
## **Degrees of freedom of movement**
The fact that the Earth's gravity gives us obvious "up" and "down"
directions is secondary to the fact that it keeps practically everything
on the surface of the Earth. Until the development of aircraft
(including balloons) there was no vehicle that could even consider
traveling up or down. All long-distance travel was basically two-dimensional.
In fact, even with modern airliners long-distance travel is *nearly*
two-dimensional; a flight of 3000 nautical miles will rarely get even
8 nautical miles above sea level.
Even if you had an obvious naturally directed frame of reference in your cluster, early navigators would have to develop ways of directing their craft
that humans have only had to deal with when sending spacecraft to the Moon
or to more distant places.
## **Visibility**
Although you have line-of-sight to practically anywhere you would want
to go, the space between you and your destination is still filled with
breathable air. The thickness of this layer of air around the Earth
is only a few kilometers--11 km up, density is less than 1/4 of that at
sea level, 20 km up, it's less than 7%, 32 km up it's less than 1%.
So we can still see stars at night.
[Wikipedia says visibility through air would be limited to less than 300 km even in perfectly clear conditions](https://en.wikipedia.org/wiki/Visibility#Derivation)--and with entire islands floating around in
mid-air, it seems likely that other particles would be floating about, too.
If the air between islands is *really* thin, though, that might allow
the radius of visibility to be greater than it would have been in
a uniformly thick atmosphere. And you have magic.
So visibility could be on the order of hundreds of kilometers,
less if you allow any kind of clouding or floating particles.
You could probably arrange to have visible stars in the distance
(maybe only at the distance of the Sun from the Earth--they do have to
be bright enough to be visible through all that air).
But it sounds like that is not a planned part of your world;
it may make more sense for the radius of the cluster to be much
larger than the distance anyone can see from any island,
even with a strong telescope.
## **The map keeps changing**
If even a strong storm can move an island significantly, charts can't be
very precise. If you could somehow plot the exact direction to an island
that was much farther than you can see, it very likely wouldn't be where
you expected it to be when you got there.
## **Technology matters--a lot**
At a very low level of technology I think it is unlikely that navigation
would be advanced much beyond having knowledge of which islands are close
to which other islands.
Since the islands drift, even local "sky charts" would be impractical;
but people on each island would either be able to recognize the
nearby islands or would know which was which by having tracked their
motions across the sky.
Directions a sky captain would give would basically be,
"See that island there? Go to it."
If the island was too far away to see, you probably want to stop at another,
nearer island to get further directions anyway.
**Edit:** I wrote most of the rest of this answer before I noticed the comment about "no radio ... tech level similar to the 1500s."
That comment makes most of the rest of my originally-written answer obsolete,
but I'm leaving it for reference, underneath the separator line below.
To have reference directions that one can give directions relative to,
the way a captain in the 1500s could give directions relative to the
compass card, would require more effort to keep track of the necessary
reference directions than I think could be supported by the technology.
You'd need either a very stable gyroscopic system or a lot of computing
power to figure out what direction was what based on what you could
see (and on how much what you saw was likely to have moved since it
was last "charted"). So at that level of technology, as far as
directions for navigation go,
I think "go to that island you see there" is it.
Directions to *manuever* a vessel could still be given by angle of
yaw and angle of pitch (having already
assigned yaw, pitch, and roll axes to the vessel),
but those would be directions relative to whichever way the vessel
happened to be oriented when the directions were given.
---
Once you have radio technology then the visibility problem becomes a
lot less severe. Radio waves will go further than light through the
inter-island atmosphere, and you could set up radio beacons on each
island that could be identified and located from very long distances away.
The nature of the directions would be similar; the difference would be
that rather than heading to where you can see the island,
you would head in the direction that your radio locator indicated
for the desired beacon.
The fact that the island may drift is of little consequence, since
the beacon will go wherever the island does.
## **Giving an arbitrary heading to the helm**
Eventually, it might be desirable to be able to give some kind of
"heading" direction to the helm of a skyship that doesn't depend on
having a visible island or a beacon in the direction you want to go.
The question is how long it would take for the usefulness of such a thing
to outweigh the technical difficulty of achieving it.
(Keep in mind that the problem of getting from point A to point B without
getting lost at sea, which prompted so much of the development of navigation
on Earth, would already have been solved.)
There are two obvious ways to indicate direction in three-dimensional space.
One is three-component Cartesian vectors; the other is some sort
azimuth-and-elevation system or localized spherical coordinates
using two angle measurements.
Steering by vectors does not seem attractive; do we ever tell someone
to sail "twice as fast to the east as you do to the north"?
So two angles it is. The question is, what are the reference
directions from which to measure the angles?
Any such reference directions would probably be determined by
a universal coordinate system imposed on the entire cluster;
I don't think there's a general solution for specifying direction of
travel without that. The universal coordinate system could
itself be spherical, cylindrical, or Cartesian (or possibly something
else, but I can't think of what).
There is an identifiable center of the cluster in the middle of its "heart".
This gives you an "outward" direction (away from the center) at any
other point in the cluster. This could be one of the reference
directions for the azimuth-elevation directions that skyship captains
would give to their helms; but if so, it pretty much requires that the
universal coordinates also be spherical.
Another possible source of direction could be a magnetic field
throughout the cluster.
The lines of the field don't have to be completely parallel, just pointing
in the same general direction within the space between islands.
A magnetic needle could be mounted so that it always points "north"
parallel to the local lines of the field (unlike a compass used for
navigation on the Earth, which projects the lines of the field onto
the Earth's surface).
Assuming there were known ways to estimate and compensate for the
deviation of the magnetic field wherever the skyship might be,
this would give one axis of a universal system of coordinates that
could either be cylindrical or Cartesian.
The problem with either spherical or cylindrical coordinates, however,
is that directions get ambiguous when you're too near the main axis
of the coordinate system. Which direction is it to New York from the
north pole? Which direction to Beijing? They're both *south,* which is
no help in figuring out how to fly to one of those destinations.
So I think the universal system would probably be Cartesian.
One axis (aligned with the average magnetic field if there is one,
otherwise aligned with some very important route or with an arbitrary
direction) would be the "north" axis; another would be the "prime" axis.
So that every skyship can always determine the orientation of those axes
despite the drifting of the islands, people might set out a regular grid
of floating radio beacons, with propulsion powerplants
so that they can (almost) hold their stations relative to each other.
Each beacon would report any deviations in its relative position
by a signal carried by its radio transmissions.
By triangulating a few of these stations, you could always determine
where you were and (most importantly for the purpose of this question)
which direction was parallel to each of the axes from wherever you
happened to be.
It is also possible that a skyship would carry a gyroscopic system that
(mostly) stayed aligned with the axes of the universal coordinate system,
which might be more convenient for knowing which direction is which from
moment to moment (especially if you don't have high speed computers to
figure it out for you),
but I think the regular grid of fixed beacons would still be useful
to help correct any wobbling of the gyroscopes and to reset them if
they tumbled completely.
Then to specify direction, think of an imaginary Earth's surface positioned
with your skyship at the center of the globe, with the north pole
exactly "north" from the skyship and the point at zero latitude and longitude
exactly in the "prime" direction from the skyship.
A command to head 30 degrees north, 50 degrees east would mean
to point the skyship toward the point at latitude 30 N, longitude 50 E
on that imaginary globe.
(But I think it is likely that the "latitude" direction might be given
as an angle *away from* the north direction rather than toward it;
that is, you might say "head toward zero south" if you wanted to
head exactly in the direction of the "north" axis.)
[Answer]
## It's all convention anyways
The simple answer is to pick a point and two orthogonal directions arbitrarily.
For instance, the center of your capital island is the point of origin, north is towards the North Star and up is towards any perpendicular direction of your choosing. Once you have north and up, you can infer south, down, east and west.
## Why so Cartesian?
Cartesian coordinates express a point relative to an origin based on three orthogonal axes. In your case, north, east and up are the three axes.
Now you take these axes, and do something different. North and east form the polar plane. Up is still up and should be perpendicular to your plane.
Now you express coordinates based on: distance to origin, angle on the polar plane (or polar angle, in all 360°), and angle to the up direction (azimuth angle, from -90° straight down to 90° straight up).
You now have a [spherical coordinate system](https://en.wikipedia.org/wiki/Spherical_coordinate_system).
Why is this better? There are no arbitrary north, south, east, west, up and down direction. There is however an arbitrary plane, which includes an arbitrary 0° polar angle and coincides with the 0° azimuth angle. Remember, it's all convention anyways.
In a 3D space, expressing relative coordinates spherically makes generally more sense than Cartesiannally. You want to know an obstacle is X meters away in that direction. That it is X,Y,Z meters away from a point of origin that you yourself are U,V,W meters away from doesn't seem quite as useful.
## It's all relative anyways
Absolute coordinates (whether Cartesian or spherical, or else) are of little practical use in most cases. In this case, I would advise Cartesian coordinates because it's easier to figure out Cartesian geometry.
Relative coordinates make more sense in practice. We experience the world relative to our point of view. You instinctively know where front/back/left/right/up/down is relative to you. Apply the same logic to the ship. In this case, I would advise spherical coordinates.
[Answer]
## Hubwards, Rimwards, Turnwise and Widdershins.
If there are no fixed points then you have a problem. If there's an orbital mechanic of some sort then you have one of your directions, with the turn or against it.
You have to remember that everything is ultimately arbitrary. Since you're in three dimensions then you'll have to pick three cardinal directions, give them fix points to plot relative to and you're done. Don't forget about the North Star (Polaris) and the Southern Cross when you're thinking about this.
---
## Glowing Islands
You have constellations. They consist of other islands but some will be brighter than others, they'll form patterns, hence you can navigate.
To a certain extent this is "all roads lead to Rome" grade navigation, but it gives you a basis to allow ships to get around. Remember that we've been sailing the seven seas for thousands of years but a method of accurate navigation on open seas was only developed 200 years ago.
Skyship captains will be plotting courses between known points, spending as little time free navigating in open skies as possible. They'll be island hopping. The journey from A to Z passes through every point in between.
[Answer]
So, since the question does not address some vital issues, I'll make stated assumptions of my own to start:
1. IF Air pressure is not constant throughout then you have an easy UP-DOWN dimension. Down is the opposite of the direction of Gasping Death. We'll instead assume that the air pressure is constant somehow (transparent handwavium alloys)
2. IF there are outer stars visible, then you can use them to define a simple 3-D coordinate system. Pick a North Star. Pick another bright star at a 90 degree angle to it. Call that your reference direction ♈ as your vernal point that defines your plane of reference. Find the island in the center of your air-ocean, or the empty air-filled void therein. You now have all you need to calculate the **longitude of the ascending node** (☊), **Inclination** ($i$), and the **Argument of periapsis** $\omega$, from an idealized position in the center of the air-filled sphere.
[](https://i.stack.imgur.com/pSW3K.png)
Kinda like this, but likely with empty air rather than earth in the center, unless there is a **central** island
3. IF the Islands move in a regular orbital pattern (ellipses), you need just a few parameters to know where they are at any point in time (orbital distance from the imaginary center of the sphere, measured in mega-**Yoshis** plus 3 for their stated positions at the start of the Epoch, $T\_0$ and from the center plus 3 corresponding velocities for their movement during the next $\Delta t$ interval. Depending on the shapes of the orbits, you may need also need Eccentricity ($e$), and the Semimajor axis $a$, but we'll assume clean circular orbits for simplicity.
This means you can just have a set of navigational charts, assuming your captains have moderately accurate clocks. If it is Huesday, Vapril 4th around the first orbit of Sony, Mario Island will be at ($MY$45$i$35°☊60°$\omega$39°) moving with a speed of ($MY$0$i$5"☊6"$\omega$0.3") over the next Sony orbit.
[Answer]
If the islands glow, then you can see other islands in the sky. You can navigate by having a map of the relative positions of these islands.
Do the islands travel in orbits around something, or are they just floating motionless? Well, if they have gravitational fields, then if the laws of physics as we know them apply, they attract each other, so they have to move in orbits or they will slowly drift together and collide. How long has this place existed? How big are they and how far apart are they? Are there other forces involved? Etc.
But moving or not, if the movements are predictable, you could make maps. Navigation would be simpler than on Earth, as you can always see your destination in the sky. Well, assuming it is not directly behind another island from your perspective, and that it's light is not drowned out by other light. If it's far enough away that it's light is too dim to see or to distinguish, then you'd use your maps. You'd say, yes, island A is far away, but you can see from this map that if we head toward B, and then from there head toward C, that then we'll be able to see A and complete the trip.
I think the simplest method of describing positions would be to use Cartesian co-ordinates, i.e. x, y, and z with perpendicular axes. If there is no well-defined center of this place, pick an arbitrary point to be 0,0,0. Like the largest known island. Or some island that is a recognized social or cultural or scientific center. If there's no natural direction for the axes, just pick arbitrary directions and who cares? Just like, on Earth the equator and the poles are naturally-defined places, but there is no natural zero longitude. So we picked a place, Greenwich England, and we go with it. It could have been anywhere.
As to terminology: We use north, south, east, and west because they come naturally from the fact that we live on the surface of a rotating sphere. In a free 3D space, if there's no center of rotation or anything else that defines a natural axis or basis of direction, you'd just have to pick something arbitrary. I imagine people would just make up names. They'd plot the 3 axes in arbitrary directions, and then make up names for those directions. So they call them fwac and plugh and boobaloo or whatever. If they were living and working with these names every day, they would seem completely normal and natural to them, and words like "north" and "west" would be strange, unfamiliar terms that would have to be explained.
[Answer]
The answer is unfortunately as boring as they come: they would tell directions using the information they can acquire.
This issue you raise is actually a real issue for robots today. Consider your Wii-mote on your Nintendo Wii as the simplest example. Point it in the air, straight up. Link responds by holding his sword up. How did it know it was pointed straight up? Now point it at the screen to select an item. How did it know which item was being pointed at? Did you know the answers to these questions are different?
In the case of the Wii-mote, it has 3 sensors:
* A 3 axis accelerometer, measuring acceleration
* A 3 axis gyroscope, measuring relative angular position (if you have the Wiimote plus)
* A small IR camera on the front
When you hold the Wiimote up high, it notices a roughly 9.8m/s^2 acceleration from the accelerometer. Because the Wii is played on the surface of the Earth, not on the moon or in space, it can deduce that that acceleration is *probably* the acceleration of gravity. From that, it can determine the orientation of the wiimote pointed up. In fact, if you swing it around, Link can swing his sword in the game because we can look at both the accelerometers and the gyros and integrate them to get a remarkably good estimate as to where the Wiimote is.
However, this is no where near accurate enough for pointing at a screen. The sensors just aren't accurate enough to pick up the fraction of a degree difference in where things are on screen. Worse, it doesn't even know much about where the screen *is*, so it doesn't know the conversion from degrees to pixels onscreen. The Wiimote has an IR camera to help with this. If you point it near the screen, it sees the two bright IR LEDs on the Sensorbar, and it can use that information to deduce where it is being point at, as long as it's somewhere near the screen. *(In fact people with broken sensorbars have been known to replace the IR LEDs with candles at the right spacing, with the same effect!)*
I point these things out because your space captains would not be foolish. They too would use every bit of information available to them, including magical devices which are outside of the realms of physics. That being said, here's a few examples of real life ways we do this:
**Stars**
[](https://i.stack.imgur.com/xyGlbm.jpg)
There is a long history of using the stars to provide a universal alignment. You can't tell your position from the stars, but you can tell your orientation, and that was the specific question you posed here. If you can identify patterns in the stars, you can use those stars to figure out which direction you're pointed. Many amateur astronomer telescopes actually have an option to shoot 2 or 3 stars, and have the telescope's computer figure out the orientation of the telescope. From that point on, you can look up any named star, and it figures out where to move the gimbal.
**Gyroscopes**
[](https://i.stack.imgur.com/Umtfjm.png)
Gyroscopes have been used for a very long time as a way to get a very accurate measure of your orientation relative to when you started. They do this by spinning a large mass. Due to the law of the conservation of angular momentum, this mass will not want to change the direction you spin it when you tip it. (There are actually many classroom setting experiments you can do to show this!). If you put the gyro on 3 gimbals, so that it can rotate in all directions, the spinning disk in the middle of the gyro will remain in the same orientation (roughly), and the gimbals will all permit the body of the gryo, and whatever is holding it, to move around it. You can then look at the angles of the 3 gimbals and determine your orientation.
A fascinating issue with these is called gimbal lock, when two of the axes line up. When this happens, you lose track of one axis because two of your measurements are in the same line. [This *almost* happened on Apollo 11](https://en.wikipedia.org/wiki/Gimbal_lock#Gimbal_lock_on_Apollo_11). While gimbal lock is avoidable with a 4 axis gimbal, we chose to fly a 3 axis gimbal with a neat logic circuit that, when we approached gimbal lock, it would flip one of the gimbals around to avoid the issue. During Apollo 11, they got close enough to this point that the computer started doing calculations, and ran across a bug in the code. Rather than take the whole computer down, the computer simply disabled that functionality and moved on. This meant Apollo 11 was flying very close to gimbal lock, with no protection.
This story and the star shot are related. NASA likes contingencies. They planned for this situation. If this occurred, the astronauts were to take star shots out of one of the windows of their capsule, just like mariners 400 years before them. Those angles would not be good enough to land on the moon (they would have to abort), but they would have been good enough to get them home safely!
**VOR**
[](https://i.stack.imgur.com/Fef13m.jpg)
If you ever see one of these strange contraptions at an airport, it is a VHF Omnidirectional Range antenna (VOR). It outputs two signals. The first is a sine wave encoded onto one AM channel. The second is a phase delayed version of that same sinewave encoded on a different channel. Each of those antennas you see in the picture outputs a different phase. Thus, if you listen to both frequencies, and extract those two sinewaves, you can figure out which direction you are, with respect to the airport, just by comparing phases.
This one is different from the others in that it is an active system. It requires an antenna on the ground. However, this has some interesting advantages that you can't get from the passive version. For example, you can start to tell range, not just angles. This is enough to get positions. If you can find two VORs stations that you can hear at the same time, you can triangulate. If you can't find that, you can fly perpendicular to the VOR signal, and use your groundspeed compared to the rate the VOR signal is changing to tell you how far you are from the station!
**GPS**
[](https://i.stack.imgur.com/C4nX0.jpg)
This might be a bit extreme for your story, but it'd be silly not to mention GPS, because virtually every computerized moving object today has a GPS receiver in it. GPS operates in a surprisingly simple and surprisingly sophisticated way to tell you your position and velocity (but not orientation). All of the GPS satellites overhead output a signal containing information about their orbits. These signals are carefully phased locked so that you can measure the relative time you receive each signal. Light, and radio waves, propagates at roughly 1 foot every nanosecond, so if you can measure the relative time it took to receive the signals to a nanosecond, you know the distance (within a foot) of where you're at! It takes a fix on 4 satellites to give you a good location for where you're at via triangulation, and there's 24 of them circling the globe.
GPS is an interesting oddity because of how precise you have to be able to measure time. In fact, it is hailed as one of the empirical validations of Einstein's relativity. The satellites are moving so fast and the timing constraints are so tight that you actually see position errors if you do not account for the time dilation effects of relativity!
**The Enemy's Gate is Down**
To close, I'd like to address one final issue that arises in these systems. You specifically mention "how do they determine up vs down if directions are relative." The answer is "they don't." Why would you try to determine something that you know you cannot determine. Instead, you define your axes in whatever direction is most convenient.
The most famous example of this that I can think of in fiction is Enders Game, with the famous Battle Room. The Battle Room, for those who haven't read it, is a zero gee room where they practice space combat tactics. Players enter from opposite sides of the field and duke it out. Ender, the main character, noticed that many people were keeping their mental orientation that they had when they stepped into the room, assigning one wall to be the "ceiling" and one to be the "floor." This caused all sorts of strategic nightmares because it fixed an axis arbitrarially -- 4 of the possible "floor" choices were technically all the same. Instead, Ender chose a 5th orientation. He told everyone to think "The Enemy's gate is down." This way of thinking oriented his team to the only axis which actually mattered in that room, as opposed to picking an arbitrary useless axis. This was a major factor in his team's success.
] |
[Question]
[
The Hindenburg was a massive failure in blimps, it practically banished them from the skies, it didn't matter that events such as the Hindenburg disaster were not as common as plane crashes today or that a whooping 2/3 of passengers and crew survived it. The shear terror of the fiery steel skeleton caused so much fear that it was scrapped.
What events could (around two or three preferably) I change or add to the history to not only keep airships in use but also have them used on par with airplanes? The only requirement is that the changes must occur in the years 1750-2000.
[Answer]
1) High availability of helium. O.M. is right, helium is a very scarce resource and only due to huge reserve produced over a very long time when the demand was minuscule it's as cheap as it is - if the reserve didn't exist and we'd only have current production for current use, a common small kid's helium-filled balloon would cost something of order of $30 to fill. Even today, with the reserve, the price is prohibitive when it comes to filling blimps.
2) Way faster development of plastics. In WWII Germany blimps caused a total crisis on accessibility of cow leather - almost all of leather production went to the balloons/blimps. A polymer coating would cost a tiny fraction of that and be far easier to build, immensely reducing the price and difficulty.
3) A speedier space program = satellites sooner in space = enormous jump in the quality of meteorological forecasts. Blimps are still at mercy of winds.
4) Better electric propulsion sooner. At least Li-Ion batteries. Cheap, light solar power would be welcome too. The primary advantage of blimps over airplanes could be the cost of operation, and that would necessitate cheap, light propulsion.
They wouldn't entirely replace airplanes - airplanes would still be used for fast travel when time, maneuverability and payload:size ratio matters. But blimps could replace long-distance trucks, freighters, sea liners, possibly "economy class" passenger airplanes. The price to operate a large fleet of blimps would be significantly lower than the price of operating a comparable fleet of airplanes, so despite all the disadvantages, they could be used for travel less expensive than airplanes.
One way to get that cheap helium: Fusion. We got a tokamak/stellator working, and it can produce more energy than it consumes, albeit not much more. Fusion power plants sprout everywhere, enormous amounts of hydrogen (from water) are converted into helium, the power plans consume most of the power they generate to sustain themselves, but they produce some surplus - and helium is the byproduct.
(the power plants can't be TOO efficient - because there simply is no economical justification to producing this huge amount of energy - the demand dictates the size of the market, with market saturating faster there would be less fusion power plants, and as result less helium produced.)
[Answer]
Not a Zeppelin, but Hybrid Airships
Something like this was seriously considered during the energy crisis of the 1970's and the idea resurfaces from time to time. John McPhee recounts the story of the Aereon Airship company of Trenton New Jersy in the "Deltoid Pumpkin Seed", where the intrepid inventors develop a hybrid airship design. The lift was to be distributed between the lifting gas inside the envelope, and the shape of the envelope itself, which was to be a wingless "lifting body" capable of aerodynamic lift in forward flight.
[](https://i.stack.imgur.com/DvHEw.jpg)
This would have allowed for a much smaller engine, and the ability to take off and land at very low speed from very small runways. Unlike a conventional aerostat (Zeppelin, blimp or balloon), it would not be positively buoyant on the ground, meaning it was less vulnerable to being destroyed on the ground by errant winds. Sadly, the company was unable to progress beyond a single flying prototype, and ran out of money.
The latest version of this idea is SolarShip, a Canadian company which has the added twist of covering the upper surface with solar cells to provide energy for the engine. Like Aereon, it has flown at least one prototype, but details of any subsequent work is lacking
<https://www.youtube.com/watch?v=yrStvYrMzbk&ebc=ANyPxKol1HrvwcxY8FuBUqJHMFd_rHodUu-enZyCJZGizad3yvXOaHUhphCmcQLliM4sUJL_br8x>
[](https://i.stack.imgur.com/4AOtb.jpg)
While the prototypes are obviously small proof of concept vehicles, Aereon had conceptual designs that would carry giant payloads, and SolarShip has conceptual designs that can carry the equivalent of a C-130 sized payload (roughly 30 tons).
The main reason that these ideas have not taken off (so to speak) is they are much slower than conventional aircraft, so amortizing their cost will take much longer (a conventional aircraft can carry much more and much faster than a Hybrid Airship). It is quite likely that the large surface area and lightweight structure will also make these airships more vulnerable to weather than regular aircraft (although less so than a Zeppelin).
Hybrid airships will most likely fulfill niche roles where low speed and high fuel economy are important. Naval escorts flying slowly over carrier battle groups bristling with sensors is one possible role, and a flying cruise ship carrying a few dozen passengers in super luxury conditions might be another.
[Answer]
First off, you are incorrect as to your analysis of the Hindenburg. Not only was it not a blimp (it's a rigid airship, not to mention the Navy's 100+ sized fleet of blimps during World War Two to spot submarines), but the crash of the Akron, the explosion of the Dixmude, and the crash of the R101 were all far worse accidents (and the Hindenburg made 60+ flights over its lifetime). They all happened before the Hindenburg even flew once. Yet they kept building them. Not only that, but Luftschiffbau Zeppelin built another Hindenburg-class Zeppelin, called the Graf Zeppelin (even though another Zeppelin with that name already existed). And even beyond that, another Zeppelin, even larger, was under construction when World War Two started. The two Graf Zeppelins and the under construction LZ-131 were all scrapped by the Nazis for war material.
So, what killed the Zeppelin? Well, let's go back. Back to the past. How far? About a hundred years. World War One was, arguably, the golden age of the Zeppelins, with over 100 built in a span of just four years. But at the end, the Zeppelins weren't all that effective as bombers. Even so, the Treaty of Versailles essentially killed the German airship industry. Despite that, two more Zeppelins were built right after the war. LZ 120 "Bodensee" and LZ 121 "Nordstern," both of which were seized by the Allies. However, LZ 120 managed to operate for a decent amount of time, and despite its short timeframe of operation, it transported over two thousand people across Europe. Pretty good, if you ask me. But what really killed the Zeppelin? It wasn't the Hindenburg, the Dixmude, the R101 (although that did kill British airships), or the Akron (which was succeeded by the Macon, both the Akron and the Macon were flying aircraft carriers, btw). What killed the Zeppelin was The Treaty of Versailles, the Nazis, and World War Two.
The Treaty of Versailles essentially demanded the dismantling of the German airship industry. After the LZ 121 was seized, no new Zeppelins until LZ 126, later the USS Los Angeles after being handed over to the USA, were built. Had Germany been able to keep their airship fleet and refit them for airline service, as well as introduce LZ 120 and LZ 121 in peace, a fairly healthy Zeppelin airline would've likely been in operation throughout the 1920s, perhaps stretching into the 1930s with the introduction of the Hindenburg-class ships perhaps occurring slightly earlier.
But, let's assume that even this optimal situation does not occur.
The Nazis. Always ruining our fun. After the Hindenburg disaster, the Zeppelin company was able to appeal to the US to get access to Helium. There was more than enough, and due to its rarity venting it would be out of the question (many hydrogen filled airships vented lifting gas as they burned their fuel). As such, a one time shipment would be all, save for the small possibility of loss from leaks and other potential problems. And, just as the US was about to give the Helium over (under the condition that it be used only for civilian purposes), the Nazis began an aggressive annexation of Austria. The US thus refused to supply the necessary Helium that the Zeppelins needed to continue commercial operations. Even so, the second Hindenburg-class ship, LZ 130, made 30 flights (none were for commercial purposes) before it was scrapped.
World War Two changed just about everything. Beyond the Zeppelins being scrapped, the war provided an enormous impetus to develop long ranged bombers and troop transports. As such, the new DC-3 was built in such huge numbers that after the war it flooded the market for airliners. The massive increase in aviation technology as a result of World War Two made Zeppelins irrelevant for passenger carrying purposes.
So what are we left with? Well, we have a few options to make Zeppelins grace our skies once more.
Option 1: Change World War One or the Treaty of Versailles. Doing this would probably enable the Zeppelin industry to flourish, perhaps over one thousand rigid airships could be in service by 1940? Sounds like much, but if they could build 25 per year in Germany alone...
Option 2: Change other rigid airship accidents as well as the Hindenburg. The Dixmude, the Akron, the R101. Remember, the R101 was the accident that killed the British airship program. If those accidents didn't happen, rigid airships may still grace our skies. Not all of them would be Zeppelins, but even so...
Option 3: The Nazis do not come to power. This may actually make construction of the Hindenburg impossible, but no one really minds a little bit of handwaving. Or maybe leave the Nazis, but delay World War Two or perhaps make it never happen.
Option 4: Airplanes are never invented. With no competition due to the nonexistence of dynamic lift vehicles, static lift(airships, balloons) is the only option.
Option 5: Handwavium. Basically some miracle material that reduces an object's weight. Would also create interesting airplanes.
Option 6: Some sort of combination of the above, or something you come up with.
All of this is available on the internet, although do be wary, LZ 120 was the designation of another Zeppelin. There are some weird things involving Zeppelins, but until World War Two, Zeppelins were the most capable aircraft in the world. Capable of non-stop flight across the Atlantic, carrying tons of payload, or, even during World War One, later on in the war they had designs which could carry 3 metric tons of bombs, rivalled only by bombers in the late 1930s and early 1940s. Almost 20 or 30 years earlier.
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* Easy availability of helium rather than hydrogen. Part of the problem was the [strategic reserve](https://en.wikipedia.org/wiki/Helium_Act_of_1925) of the largest producer.
* An established infrastructure of docks on skyscrapers in the center of metropolitan areas. Legal precedents that say when there is a dock on the highest building in town, nobody is allowed to build higher in the flight path.
* No WWII, no war scare, and perhaps airships will compete with something like the [Ford Trimotor](https://en.wikipedia.org/wiki/Ford_Trimotor) rather than the [DC-2](https://en.wikipedia.org/wiki/Douglas_DC-2).
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Come up with pretty much any reason for fossil fuels to have become incredibly scarce, and the fuel efficiency of lighter-than-air transport would have tipped the scales towards blimps over traditional aircraft.
Say.... what if WWII had gone on a bit longer, gone nuclear, and made all of the middle eastern reserves glow?
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Some of the current commercial designs - <http://news.discovery.com/autos/military-vehicles/massive-airship-flying-start-130205.htm> and <http://www.smithsonianmag.com/innovation/how-an-airship-the-size-of-a-football-field-could-revolutionize-air-travel-180950007/?no-ist> -
focus on the ability to carry a heavy payload without needing a landing field. This effectively makes them more fuel-efficient long haul helicopters with the disadvantage that they're slower.
I think if you wanted an event to drive this change you need a high-profile rescue or relief effort that uses airships to either deliver resources to a remote area with rough terrain, rescue people from the same problem, or both. This requires airships to be available so the linked commercial efforts are a prerequisite but a high-profile positive event would drive funding into their development and could allow them to have become mainstream decades ago.
Another possible event is something that grounded planes and helicopters but didn't prevent airships from flying. I'm having trouble coming up with something since events such as volcanic eruptions would also clog the engines powering airships so while they wouldn't have to land they also wouldn't be able to manoeuvre. They still might be effective enough that a wide-spread simultaneous chain of volcanic eruptions makes airships the only viable way to get supplies into affected areas (perhaps heavy ash drop makes roads and railroads impassible?) and airship tickets the only way out.
You also really want that event or disaster to have an extended timeframe so that it's sensible to rush-build a fleet of airships to meet the problem. This fleet then continues to be used after the disaster, providing economies of scale for the growth of an industry around them.
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The title is a bit different to the question, but there's a reason to that. I am currently in the worldbuilding stage of creating an alien planet, mainly the wildlife, and I may have run into a problem. Back to the title, at one point on Earth, Dinosaurs and large reptiles filled the majority of niches (I'm talking specifically land-borne life and excluding invertebrates). After the mass extinction, the empty niches were filled by mammals and birds. focusing on mammals, they were only able to fill those niches once the dinosaurs had died off and left them behind (correct me if I'm wrong).
On my fictional planet, lets call it Xenoterra for now, there are two dominant groups of animals, the mammal-like, quadrupedal group, and the more reptilian, six-limbed group (the niches usually filled by arthropods and other invertebrates on Earth are filled, on this planet, by very similar animals). If we were to think of these two groups as the equivalent of dinosaurs and mammals, (birds falling into dinosaurs because that's what they are) **could they have evolved at the same time, filling the niches but not competing to the point of one being dominated?** Note: I'm not including the difference in size into the equation as the dinosaur and mammal part is just a comparison, the creatures in question have the same range of size and adaptability. The question uses an Earth example but in no way goes by 'Earth rules' but the ecosystem is similar. My creatures are *not* dinosaurs and mammals, I'm comparing them to dinosaurs and mammals because of the similar circumstance.
this question is definitely open to editing so if you want more info tell me. I might be slightly late to answer though.
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As long as they aren't in direct competition and are able to fill different niches effectively, they can coexist.
We don't know enough about dinosaurs to answer many of the hard questions here - body covering, movement speed, and warm-bloodedness will play a huge role in determining which roles each group is better at overall.
Of course, since we aren't talking about real dinosaurs and mammals here, you can come up with whatever diversification roles you want.
On modern Earth, for example, reptiles thrive in deserts. This is largely because cold-blooded animals need abundant heat to get moving, but on the whole require less food than warm-blooded animals do. Where food is scarce and sunlight is plentiful, they often out-compete mammals.
Large, slow predators can coexist with fast, weak ones if their preferred prey defend themselves with armor/fighting or fleeing, respectively (on our world, lions and cheetahs coexist for this reason - cheetahs hunt what lions can't catch, lions hunt what cheetahs can't fight). Reptiles (at least modern reptiles) are prone to being slower and tougher than mammals overall, so you can have an ecosystem where speedy felines hunt ungulates while hefty tyrannosaurs prey on armored ceratopsians and so on.
My guess is that on a planet such as yours, the reptile-like animals and mammal-like animals would tend to be specialized for whichever role their particular group performs best at, for the same reason that most birds don't take on mammal-like roles; even though exceptions like kiwis and penguins exist, they usually can't out-compete mammals for very long in non-flying niches. So if you diversify them according to the above rule, speedy dinosaurs (like raptors) and heavyweight mammals (like bears) might have a hard time.
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Mammals and dinosaurs coexisted, and during the Triassic there were mammalian creatures which were dog and bear sized, alongside dog and bear sized Dinosaurs and even a wide variety of crocodilian creatures, all swarming into the same evolutionary niches (for example, fully aquatic crocodiles who's legs had evolved into seal like flippers).
Of course by the end of the Triassic, crocodilians were regulated to the shallow waters by the edge of rivers and lakes, while mammals were pushed down to fill the niches filled by small rodents and shrews even today.
So the question is "why". Evidently, you can have multiple species attempting to fill the same nieces for a short while in evolutionary terms. After the extinction of the dinosaurs, several varieties of birds grew to become top predators in some places (the Terror Birds), but eventually they were overtaken by mammalian predators. Similarly, marsupials have or had evolved into many niches, but only in Australia, where they were isolated from competition, did they thrive until recent times (and humans both hunted many to extinction and brought mammalian competitors which displaced many marsupials from their niches).
So in evolutionary terms, the answer would seem to be that one type of creature is more adaptable and more flexible in filling a niche than any other. Dinosaurs seem to have been *very* adaptable, filling niches on land, sea and air and regulating all competitors into very small and marginal niches. While we usually think of dinosaurs as giants, this is an artifact of how well larger skeletons are preserved and the "wow" factor in displaying them. In reality, there must have been thousands of species ranging from chicken sized to the immense Sauropods.
So the short term answer is "yes" there can be periods where several different groups are trying to establish dominance over environmental niches, but this is only going to be a short term time frame. I would also suggest that it coincides with the end of a previous epoch, where the formerly dominant species has become extinct, opening up multiple niches for the competitors to move into.
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Size and speed are the key, specially when we are discussing the dominant carnivores. Mammals were only able to fill the dominant land animals group because they were never able to reach the size of the mighty dinosaurs (on Earth). Even if today you introduce a small population of deinonychus and utahraptors (20 individuals of each type) in the american wilds, chances are that they will flourish and replace the mammalian carnivores within 10 years, provided that they can fit in with the extreme cold conditions prevailing today in North America.
I have pointed it out in the past too, and would like to stress on the point now again, that in world building process, you are the decision maker, not the laws of Earth. So the question really is not ***if*** dinosaurs and mammals can coexist as dominant land animals, but whether you ***want*** to put dinosaurs and mammals together in that role or not.
That is, if you do decide to put dinosaurs and mammals together on your planet, you may want to give them equal physical attributes, specially for the carnivores. For example, if you have a 20 foot long carnivorous dinosaur, you would need to put an Andrewsarcus sized mammalian carnivore in the same habitat to equalize things. Similarly, for 40 and 50 long sauropods, you would want to place alongside them.
Or you may want to distribute the ecological roles more distinctly. That is, the larger and more prominent herbivores and carnivores be restricted to dinosaurs while smaller and less prominent roles be handled out to mammalians. That would mean you can go on putting Tyrannosaurus, Albertosaurus, Gorgosaurs, Allosaurus sized prominent carnivores in dinosaur league and put sabertooths, Amphicyon, Arctodus and other such carnivores in the same habitat which fill the niche of smaller sized carnivores. (God have mercy on the herbivores of that planet in that case because it appears such an ecosystem would be a very unstable one.)
So all in all, it is not a question of "if" the two animal types can coexist but "whether" you want them to coexist or not.
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Isolation. Different groups underwent adaptive radiation separately filling the niches in isolated areas. Think Australia and New Zealand on Earth.
Later, once a rich variety is established, something more can happen to remove the barrier and allow more intermixing.
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In order to do this try to work out what advantages each type of lifeform has and then realize that they will tend to move towards lifestyles that match that advantage.
So for example if you have your dinosaurs cold blooded then they would be sluggish and slow moving during the night and during cold weather, most likely hibernating through winter. Mammals on the other hand would be able to be active at night but do not scale up to the same size and need a lot more food to keep going.
This gives an immediate niche where the dinosaurs tend to be larger predators active during the day and tending to hunt infrequently but in large amounts. On the other hand mammals would tend to hunt at night or in early morning when the dinosaur types are still sluggish. When food is plentiful they would tend to flourish but in times of drought or famine the dinosaurs survive much longer.
Given this you can see how a dynamic system can easily emerge where certain areas are dominated by mammals, certain areas by dinosaurs, and then others have both mammals and dinosaurs competing.
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If, in your world, this is still a legitimate question, you might consider partnerships between the two species. Is there too few dinosaurs for them to hunt sufficiently alone, or could they rely on the partnership on these mammals in some way? Of course, the mammals would have to be getting something equally necessary from the dinosaurs etc.
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Does the position of the sun in a hollow earth scenario affect the way light scattering would "color" the sky?
My understanding is the reddish-orange color during sunrise/sunset is caused by the sun being at a more oblique angle in contrast to the standard blue when the sun is fully up.
My intuition states that the sky's color wouldn't change much, or if it did would become a washed out version of whatever it normally would be, ie blue on Earth. The most dramatic coloring that I could imagine would be a gradient from say blue to red as you look from the center of the sky to the horizon, given an Earth colored sun and atmosphere. I doubt the gradient scenario is possible, but it would be neat if it was.
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Of course a true hollow earth situation isn't possible. I'm mostly interested in how light scattering works when the light source is placed in the same setup.
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I wonder if you would even have a "sky", or if you'd just see the other side of the world through a haze?
We can see the moon in the daytime if it's in the right phase after all.
The entire surface of the interior would be lit equally, so if you looked up you'd probably see the shapes of oceans and rivers, fields, and anything else "large enough to be seen from space", depending on how large the interior of your world is of course.
There wouldn't be a horizon, as the horizon is caused by the Earth curving away from us.
Instead, if you looked out, you'd see the ground gradually slope up, like a hill that just keeps going and going.
If there is enough atmosphere and distance for light scattering to make something that looks like sky it would be a constant color (pale blue?) directly above you all the time, like it was noon, and as you looked down it would slowly change to more and more visible geography.
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I'm going with Green. Or Cyan.
Here's the justification, solar wind from the central star will cause constant 'global' aurora which, although dim as seen in daylight, will constitute a large fraction of the atmosphere that is seen when looking any direction other than 'straight up'. Aurora tend to be greeny blue.
There will also be a lot of light reflected from the ground itself inside the sphere, if the interior surface is anything like our Earth. The 'pale blue dot' appears as mostly blue with lots of green and some yellows/browns thrown in.
I wouldn't expect to make out many details on the opposite side of the sphere as the sun would block most of that plus the abundant water vapour in the atmosphere will also reduce visibility.
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Interesting question.
Assuming in our Hollow Earth that the atmosphere is the same composition and thickness as the atmosphere on Earth , the gap between the atmosphere and the Internal Sun is vacuum, and that the Internal Sun has the same relative brightness and isn't superheating the atmosphere to a plasma:
**The other side of the world.**
The sun is overhead. So is the rest of the world. Unlike on earth where there is nothing above us but the light scattered off the air, in a hollow world there is also all the light scattered off the other side of the world. The angle of the Sun relative to other parts of the atmosphere turns out not to matter as the light scattered from that bit of the atmosphere also has to scatter off your bit of atmosphere, resulting in a net of very little atmospheric effect when compared to all the light bouncing from the rest of the world.
The more interesting question is *where does all the heat go*?
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I would expect that the light source would have a huge impact on the colors viewed. But assuming that the light source is similar to our sun, then I'd assume that at or near the light it would be mostly white.
However, unlike earth where from horizon to horizon, there is only air diffusing the light, in a hollow earth you have 'sides' that with the right optics, can be 'visible' all around the light source other than what is 'behind' it hiding behind the corona and mass. So you will have hard surfaces reflecting the light as far as the eye can see. So most likely as your eye moves away from the sun, it will get 'darker' and blueish until the reflections from other surfaces start overriding the view. A huge bright green forest 500 miles away 'uphill' might have a very green tinge, an 'red desert' like in Arizona might have a bit of red.
Sorry not really a hard science answer.
As I commented "I think the sky would look more like the land when you look down out the window of a 747, slowly looking off into the distance. "
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As long as the atmosphere was the same as on earth, the sky would be blue. The light would still refract the same way as on earth, with no color change.
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(Really a comment but it's too much for one)
Before this question can be addressed we need to figure out what the atmosphere is like inside the world--and that implies we need to understand how gravity works.
The thing is in the real world there's no gravity sticking things to the inside of the world. Everything is going to fall into the sun instead. Since obviously this isn't happening something wacky is going on.
If the effect is localized to the surface you'll end up with much of the atmosphere filling the world. This means you're looking through 4,000 miles of air (much of it a lot denser than ours) to see the sun--it's going to be very red.
If the effect is wide-ranging the atmosphere will fall against the shell and the sun will look like ours at noon.
Note that the sky in this case will be blue-green rather than blue. You'll get the blue from scattering but you'll also be seeing the green of the other side of the world behind it.
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I am trying to write a story where the main character is born as a dragon-like humanoid, in a culture where dragons live with them in the same communities.
The main character is to be born into this society, and will eventually discover that he is bound to a dragon partner.
I have had two ideas regarding their wings:
1. The entire species has no wings.
2. Male dragons have no wings while female ones do.
I first thought of making the dragons this way because I wanted to avoid situations where the main protagonist could escape any situation by flying away. However, while reading on the web, it seems that wings are vital to the concept of dragons people visualize in their minds.
If these creatures are wingless, would you still consider them to be dragons? Or would you think of them as another species entirely?
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Well, I'm going to undergo the assumption that these wingless male dragons are the only ones who can breed with the females. If this is true, then these are definitely one species. It's called sexual dimorphism. Go to <https://en.wikipedia.org/wiki/Sexual_dimorphism> for more information on it. Anyway, I think that readers could still conceptualize a dragon even without wings. But be specific when you describe dragons. There are so many different ways dragons are represented in cultures that I sometimes mix them up myself. Chinese dragons don't have wings, but most modern concepts of them do. So you should be fine with wingless male dragons as long as you describe them well enough.
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If the issue is that within your story you don't want your protagonist to fly, that doesn't necessarily mean he cannot have wings. There are plenty of species that possess wings or wing-like features without the ability to fly, from the chicken to the [flying squirrel](https://en.wikipedia.org/wiki/Flying_squirrel).
You can always make it so that male dragons are reasonably larger or heavier than female dragons, meaning that whilst they do have wings, they cannot get enough power from flapping them to achieve flight. They may still have the ability to glide, however, so I do not know if that suits your story.
I have also seen a theory about how dragons could achieve flight without magic, which included filling a second pair of "lungs" within their chest with hydrogen, which could be used as added buoyancy to help with flying as hydrogen is less dense than air, so will help to keep them aloft (like with humans floating on water with lungs full of air).
The hydrogen is then also used as the fuel that allows them to breathe fire, but also means that they cannot simultaneously fly and breathe fire, as they must use their reserves of hydrogen for only one thing at a time.
Using this reasoning, you could design the females as having a greater proportional second lung capacity compared to their size/weight, allowing them to achieve flight easier than males.
You could also give the male dragons *limited* flight ability, but if it takes a while to replenish the reserves of hydrogen, then when they have fought off an attacker using their fire breath they will be unable to fly again until their body has metabolized enough hydrogen to refill their second lungs.
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If people can make dragons covered in fur and feathers, you're good.
Dragons, like vampires, are such an appealing concept but being fictional lets us do whatever we want with them to have our own styles and interpretations.
We've seen vampires sparkle, vampires that eat the color red. We can all think of a certain variation of the creature that came to be because someone wrote them that way.
Point is, if your dragons don't fly, that's cool. They're YOUR dragons. People might like your designs and if not, it sounds like your story has a lot more going for it than just what the dragons look like. I think wingless dragons are a fine concept.
Besides. If you've seen what Adventure Time's dragons look like, you probably wouldn't worry so much.
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Well in dragon lore a four limbed dragon (4 legs kinda) is named a drake. (There is of course the Chinese dragon but it does not have as much in common with the European dragon.)
You should also explain why they do not have wings (maybe nests higher in the mountains and males can be dangerous towards the eggs) or if your only goal is to not have dragon be really easy to get away with maybe talk about the fact that humans are far too heavy.
Or maybe the males do not have developed wings contrary to females ( hormones...)
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Most dragons can fly, but in reality are depicted to have far too small a wingspan. You could go with the conventional wingspan, but like some large birds the dragon needs to build up speed by running or falling before he can take off.
This limitation could give you the lack of escape by flying you need. If the dragon can run away far enough to start flying, he could have run away anyway.
You could also weaponize the male wings. Their wings are heavier, allowing only gliding or limited flight, add a strong possibly sharp edge and you can club enemies to death with the wings which can carry the full weight of the dragon, thats a lot of hitting power you shouldnt ignore and I eould love to see a dragon slam a wing into someone and rip their head off with the blow or something. And having a dragon break (small) tree's with it's wings to create space to fight would be a nice image as well.
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I would say that you should do the second option, because dragons in myths use wings for many things, including hunting.Plus, if only one gender has wings, it show which gender is considered better. As you said, people visualize dragons with wings, but if you went if the first, I would still call it a dragon. The Lindworm is wingless, but is still called a dragon.
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I was just wondering what kind of rule changes court layout etc would happen to have a 'basketball' game in a zero-g arena? I'm assuming the most likely thing to stay is a ball and 2 opposing baskets.
I was wondering what kinds of recreation and entertainment would happen if people had lots of easy access to zero-g. Mostly I was thinking about any sport with a ball. Soccer would have been just as good a sport to select. I was just thinking about the logistics and what considerations would be needed to 'convert' the game.
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There are a number of problems with zero-gravity basketball, so I will break down the problems and look at each one.
**The Court**
You would need a three-dimensional court, there are a number of shapes it could take but some form of cylinder or spheroid with goals at each end seems most likely. Viewing would be a problem but that could be solved by making the court out of a transparent medium and having the audience surrounding the court in all three dimensions.
**Dribbling**
Dribbling would essentially be impossible. Any attempt to bounce the ball would send you flying away from it and "one step" could be a very long distance. A lot of alternative rules could be put in place though, such as requiring players to pass after each time they touch a wall.
**Passing**
Passing would be made more complicated by three dimensions but essentially would work as it does now. The main thing to remember is conservation of momentum which means that both throwing and catching the ball would change your path - something that could be used tactically.
**Blocking**
Blocking would be tricky as team members have limited maneuvering ability once they push off the sides (unless you give them jetpacks!) and it would be very easy for them to collide. In fact, padded armour might well be standard.
**Shooting/Scoring**
The baskets themselves would need to change, but something similar to their current function could be kept. For example, requiring shots to be made from a minimum distance away, you could also place a box and a hoop inside the box, requiring people to bounce the ball into it at the correct angle.
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I would say it would evolve into soccer (football, for non-Americans).
Why?
The reason it is difficult to defend the goal in basketball is "it's way up there". It's impossible to simply plant yourself in front of the goal. Soccer goalies plant themselves in front of the goal, but their difficulty is that the goal is big. In 3d, zero-gravity, a basketball player can easily plant herself in front of the goal, so the game would have to have a larger goal to make it continue to be interesting.
As someone else pointed out, you can't dribble in zero-gravity, and you can't measure steps the same way you can in basketball. The most obvious way to keep the ball in play would be to rule out holding the ball at all. Hence, kicking. Ergo: soccer.
As others pointed out, you'd make the walls of the arena out of transparent aluminum and the audience would watch from all around, outside. You'd need some sort of technology to allow the players to anchor their hands/feet to the walls and probably also to attract them back to walls.
I'd recommend a spherical arena as that would lead to interesting bank shots. Maybe ovoid, to stretch out the play area. Prolate obloid would also lead to better bank shots than a sphere. Maybe even attenuate the ends of the ovoid so the goals are close to the foci of the ovoid.
I think this sounds like it would be an awesome sport to watch. Players doing spinning kicks that send their bodies recoiling back would look awesome.
Assuming they don't kill each other. Keeping track of other people in 3d is a lot harder than in 2d, and if neither player is touching a wall, it would be difficult to avoid a collision once you were both launched. Maybe players would wear belts/suits that would automatically detect/mitigate collisions.
Some sort of flight suit would allow for more interesting play. Having players stranded out in the middle of the arena, trying to swim through the air would be silly, but ultimately boring. You'd want the players to focus on pushing off walls (each other?) to get speed, but some ability to correct path/avoid serious injury would be good.
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Firstly there would be no floor/walls as there's no down. Instead players would be able to bounce off all six surfaces, as noted by a reader running along a wall would be very difficult (as there's nothing to push against). Typically players would bounce from one side of the court to the other.
Second I suspect there would be no hoops (because there's no gravity to pull the ball down through them), shooting would become very difficult. I suspect the "hoops" would be changed to be targets which players would aim at. As defenders could float in front of these targets the ease of shooting would be roughly countered by the ease of defence.
Bouncing the ball may be a little more involved as there's no gravity to pull the ball downwards. However I don't believe there would be as many changes as we may think, a Basket Ball player already needs to apply force to the ball to force it to rebound to their hand. I suspect simply changing the elasticity of the ball would overcome this problem. Obviously bouncing off the walls and ceiling would be allowed!
Spectators would be seated outside the court behind glass walls/floors (or perhaps the court itself is a glass box?).
I suspect the court and perhaps team sizes would be slightly smaller. As the game would be played in three dimensions there will a lot more space to cover, making the court smaller would concentrate the action (and leave less time watching helplessly drifting players).
Tickets to view games would include travel and would be more expensive!
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Only because it is an alternative to Liath's good answer:
You could make a game which looks more like basket ball by having the "ground" be covered in velcro like material as well as one's shoes. The walls and ceiling could be hard so as to not dampen bouncing off them if one does not want an "out of bounds". A basket ball can still bounce off velcro on a hard surface but it does dampen it a little (and current velcro would wear out). This is a good thing as you want the player to actively dribble it.
The hoop would be alot harder to get the ball through from the ground. Either the players can jump to the wall and ceiling (but not stay there), the ball can bounce off the ceiling (and probably the walls), or you can score by putting the ball from another angle.
While the space ball game with no "down" would be very fun (moreso than basketball or the game I am proposing) this would look more like basketball.
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I am trying to get my head around scaling of an element in the world I'm working with, so this question may give me some perspective, that I in no way have.
If we had working room temperature ambient pressure superconductors (a la LK99 type) when the "Large Hadron Collider" was built. This I am certain would decrease the complexity of the device but would it change the overall design significantly? Ie: would the trackway be shorter or just smaller as a whole?
I do not know how much of the design of the LHC is a result of the limitation of conventional electromagnets, because of heat/power consumption, to bend the particle beams and still attain the desired energy levels.
[](https://i.stack.imgur.com/0vZE4.png)
An acceptable answer does not need to be exact, just detailed enough to convey a sense of scale.
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1. The electromagnets of the Large Hadron Collider **are** [superconducting](https://en.wikipedia.org/wiki/Superconducting_magnet). Yes, they need cooling with liquid helium. Yes, this increases the complexity of the machine and creates points of failure. Were room-temperature superconductors available, the LHC would have been cheaper to build and more reliable in operation. That's all.
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> *In total, about 10,000 superconducting magnets are installed, with the dipole magnets having a mass of over 27 tonnes. About 96 tonnes of superfluid helium is needed to keep the magnets, made of copper-clad niobium-titanium, at their operating temperature of 1.9 K (−271.25 °C), making the LHC the largest cryogenic facility in the world at liquid helium temperature. LHC uses 470 tonnes of Nb–Ti superconductor.* (Wikipedia, *s.v.* [Large Hadron Collider](https://en.wikipedia.org/w/index.php?title=Large_Hadron_Collider&oldid=1191461059))
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2. The ring is so large because the protons are accelerated at 0.99999999 *c*, only some 3.1 m/s less than the speed of light. (For fun, the [Lorentz factor](https://en.wikipedia.org/wiki/Lorentz_factor) of a proton moving at maximum speed in the LHC is about 6,930!)
When a charged particle undergoes an acceleration, it emits electromagnetic radiation and thus loses some energy. The larger the radius of the [synchrotron accelerator](https://en.wikipedia.org/wiki/Synchrotron) the smaller the energy losses due to the curvature of the path. Powerful synchrotron accelerators have to be large because the maximum energy of the accelerated particles depends directly on the radius of the path. (The accelerated particles reach maximum energy when the energy losses due to the curvature of the path become equal to the additional energy imparted by the accelerating electromagnets in each revolution around the ring.)
Bonus! The lamented American [Superconducting Super Collider](https://en.wikipedia.org/wiki/Superconducting_Super_Collider) which was at one time being built in Texas would have used a ring three times as large, which would have allowed it to reach an energy about 6 times as high as the LHC. Sadly, it was not to be.
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A recently inhabited planet revolves around its sun but does not spin on its axis. This causes the daylight cycle to happen over the course of an entire year (Note that this is different from the planet being tidally locked to its star, as there still is a slow daylight cycle.) The side facing the sun becomes superheated, while the opposite side remains extremely cold. Because this planet was recently inhabited, the residents don't have large-scale establishments, partially because they must continue traversing their way around the planet so as to stay in the small habitable zone. They travel in vehicles with rooftop gardens where they produce their food and plant-based fuel.
Presuming there is sufficient oxygen, enough bodies of water, and that the planet is close to the size of Earth, would there be any fundamental problems with a civilization attempting to lead this way of life? If so, are there also reasonable ways for this society to build permanent establishments and thrive on this planet? If not, what aspects of the planet would need to change to support at least some amount of sentient life?
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It doesn't seem to be a particularly realistic survival tactic. If the inhabitants are anywhere near the equator they will have to maintain an average speed in excess of 100 km per day to avoid lagging into the hot zone. That would be very reasonable on roads (fit citizens even manage it on bicycles), but it would be hard to imagine any surface vehicle maintaining that sort of speed over mountains, valleys, rivers, seas and the generally broken ground you might expect to find on an uninhabited planet. Maybe you can get around some rough land by heading north or south, but that could significantly increase the required average speed. Vehicles tend to break down and so there would be delays for repairs. And if you don't have the spare parts you would have to abandon vehicles.
Now it would be a lot easier to move nearer the poles - for example at longitude 84 degrees (N or S) you have much smaller circles to make, which only necessitate an average speed of 10 km/day. But if you can live (get sufficient solar radiation to run your farms etc.) at that latitude, then it is probably more sensible to just migrate to the poles and stay there permanently. As the planet is not rotating, there will be no 6 month day/night cycle and it will always be twilight at the poles. So you can build permanent shelters and not risk the oblivion that would result from the inevitable irrepairable mechanical problems if you chose the nomadic route to survival.
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If you inhibited the planet by people already travelling through space, the nomadic lifestyle becomes trivial to maintain through all the stuff available to them by starship. However, it also gets trivial to build a shelter ignoring this superhot issue altogether. So, people would pick one or the other or both - depending on what suits them, because both are about as optimal for them.
So, I am focusing more on the "how early would any of our civilizations manage that":
Pace of say 50 km/day (steppes) is doable over a pasture for say horse-based Mongols. Of course, it stops being possible the moment you need to swim; and you better already know which route avoids mountains. So, either your continent neatly splits the seas in two parts, or you are getting cooked on land. Your Vikings would be able to maintain this pace across the sea as well - there needs to be a band with much higher average wind speed (or water current) than rotation so you have enough time to dock for a while for repairs, building of new ships etc. Doing both sea and land gets possible only in modern times.
Stationary, even a caveman-tech solution exists - caves. True, shallow caves would get super-heated during the very long summer, but there are many caves that are deep enough to maintain mostly constant temperature throughout the year even in such a scenario. Grab tons of snow and ice over winter, hunt stuff through the spring and put it on the ice, have nice summer holidays, then do autumn hunt, and repeat.
Animals would probably use caves as well while the fish might get a bit deeper most of the time, going to the surface only briefly to feed. Migratory birds laugh at these issues and simply fly around. Vegetation? Well, I have no idea how that survives, temperature cycles are going to be too extreme. No plants = no animals => no food.
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**Become a maritime civilisation**
I'm assuming if this planet is sufficiently earth-like, that it has oceans. Perhaps then your people's best option then is to build sailing ships, and to sail these ships between a number of temporary settlements placed along the planet's shorelines. As an added bonus, whenever dusk falls on this planet, there will be very strong winds blowing cold dense air from the region currently under nightfall to the warmer, brighter regions to the west, which your ships would be able to take advantage of to make very swift journeys across the planet.
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So I've created a cold water-world super-earth where the majority of the planet is covered in ice caps, but has an equatorial water ocean that moves north and south with the seasons. Meanwhile, much closer to the poles, it grows cold enough that, combined with the high atmospheric pressure of the planet, liquid CO2 lakes, rivers, and seas form on top of the ice sheet, complete with CO2 rain.
Is this realistically possible? Or is the thick atmosphere required for CO2 to exist as a liquid circulate heat too much for the necessary temperature gradient to form?
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You just need to compare the phase diagrams of water and CO2, and search for combinations of pressure and temperature (P,T) where both are liquid.
Phase diagram for water:
[](https://i.stack.imgur.com/tcxDk.jpg)
Phase diagram for CO2:
[](https://i.stack.imgur.com/9hlZI.png)
It looks like around 100 bars of pressure and above, both CO2 and water are liquid roughly between 0° and 25° Celsius: water is liquid between 0° and 300° Celsius, while CO2 is liquid between -50° and 25°, even though the closer you get to 25°, the closer you are to the critical point, so you wouldn't be able to distinguish between liquid and gaseous CO2.
Additionally, it's very likely that the two would mix, so you won't have water bodies and CO2 bodies as separated entities, but rather "carbonated water" everywhere. That would add to their being solid or liquid, as their solutions have different melting/boiling points.
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This is *almost* possible on Earth. Dry ice sublimates at ~ -80C and temperatures like this are commonly seen in Antarctica (deep ice cracks go all the way to -100C.
We do have an impressive difference of about 120-130C between the poles and the equator. What we don't have is enough partial pressure of CO2.
On the other hand, even 1/10 bar of CO2 will create a strong greenhouse effect, leading to equalization between equatorial and polar temperatures. See e.g. Venus. You can get your solar irradiation as low as you want and seasons as harsh as you want, but you won't get enough temperature difference in order to allow both liquid water AND solid CO2 on the same planet.
Edit:
This answer assumes the wrong question - liquid water plus dry ice polar caps. Not sure why I got it wrong.
As the answer from L.Dutch suggests, at high enough partial pressure of CO2 water and CO2 mix freely and have a continuum of melting/freezing and evaporating/condensing temperatures.
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The world is a desert, and it's **awfully** windy. The wind is as unpredictable as possible with an average speed around 150km/h. It's usual to see wind reaching 300km/h once every three days.
The human civilisation has grown in protected areas to become cities or villages. They have water, wood, food, livestock, but no motor. Few people have crossed the desert from one city to another and even fewer made a fortune by bringing back unknown goods.
I'm already rich but I want more by starting a business selling goods between cities.
How do I secure the transport between city A and B?
1. I want to protect the goods
2. I want to be able to grow my business to a big scale
3. I don't want my *potential* employees to betray me
*The idea for this question came to me from the french book [La horde du contrevent](https://fr.wikipedia.org/wiki/La_Horde_du_Contrevent)*
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I would consider it to be a very controversial topic. On the scale of ships ramming at high speed in the Star Wars universe. And you will probably not like my answer.
When you add a particular part in a world, you need to take into account how it can be utilized by people.
Currently wind speed that is considered to be economically viable is about 25 km/h. Wind energy per area grows as speed^3. At 150 km/h energy per area is 200 times more. And economical viability is very strongly correlated with this energy per area.
You may say that wind speed is too high for our existing sails, designed for our weak wind of 25 km/h. But lets consider this, when did we make our first tech that was able to reach 150 km/h? Probably tens of thousands of years ago, with a bow. We added feathers to the arrow, thus creating a mechanism that operated at such speeds. Using extremely primitive tools and materials and while being restricted by weight. You may say that it doesnt count, arrow isnt really using the wind, just tolerates it. Then lets consider more modern example, a plane. It can fly at speeds of much higher than the wind speeds in your world. You may say that it is too modern to exist in your world.
But here is my main point: we did not suddenly invent the wing when we were able to manufacture the parts needed for the flight control. Arrow's tail is a wing just as much as plane's wing is. Idea behind it is primitive, and there is no need for controlled flight in your world, no need for all of that complexity.
The only reason that we did not use the wing earlier is that we had no use for it. Our tech didnt allow to use the wind economically, because of how little energy in the wind we have.
What would we do if we would have such winds? We would build wings from stronger materials. Material strength is really a non-issue for a wind, we knew metals for thousands of years. The only reason we used weak materials for our sails on ships is because of the weight requirement, ease of use, and lack of need for stronger material. Why use more if you can use less?
Lets consider a sword. We made them thousands of years ago. And it is sufficiently close in shape to a wing to be used as is, even better if some thought to optimise it would be used. Yes. Full metal wing is what im leading to. Because why not? What can stop a person from doing so? lack of metals in a desert? Thats where I consider author didnt think through his plan again.
Sand is eroded material, mostly silicone, aluminium and iron, in a form of oxides. Lots of other elements as well. But this is enough. Magnetism is known for thousands of years as well. And sand that is flying over you is just an amazing source of iron. All what you need to do is to stick some magnetic piece out for a second, and iron oxide dust will stick to it, and wind will carry away all the non-magnetic particles, thus doing all the mining and refining for you for free! I cant even imagine a world where it would be easier, even in theory.
Currently there is a few percents of iron in sand. It is a lot. Even if you try to explain it away with extremely low iron content, the ease of mining completely negates it. Even at parts per million, that would make you rewrite the whole stars and biological evolution, people will still be able to mine it due to ease of magnetic filtering in a sand storm.
Now, what can you do, having almost infinite amount of energy from a full metal wings and almost infinite amount of iron oxide from the magnetic filtering? Well, you use it to close the production loop.
We didnt use magnets for motors for so long because we didnt really have much experience with quickly spinning things and magnets together. Our first quickly spinning thing was probably a steam toy from Greece, but there was no magnets nearby at that moment. Still that shows that our metallurgy was ready even back then. And then for thousands of years our spinning things that we actually used a lot were too slow for a magnet in them to do any useful work. Electric motors power per edge speed grows as speed^2, so fast speed is necessary to notice or use it.
Having a whole civilization built around quickly spinning things for early work mechanisation, and being constantly exposed to magnetic dust makes the chances for them to discover the path I am describing almost inevitable.
So, what do I offer? I offer to use a car with a metal wing if tech is low. We have those today for a beach and desert racing. It doesnt have moving parts other than wheels and, ideally, a turning sail that looks like a fish's fin. We have known wheels for thousands of years too. And a blacksmith can make the wing. Either as one large piece or as segmented armor, riveted together. This idea operates by extracting the work from the speed difference of the sand and wind. Doesnt matter how weak the sand is as a basis, you always can make wheels pressure less by making them bigger, and counteract wind's pressure by making the body more streamlined and heavier. All the way to the sand ship if necessary. Yes, a full metal sand ship. With metal sail.
[wind car](https://www.renewableenergyhub.co.uk/blog/wp-content/uploads/2016/06/Formula-Zero.jpg)
More high tech version would have a large metal propeller, like planes do, and will use the energy internally for movement and other uses. By high tech I mean more than one blacksmith per habitat.
There is no such thing as too much wind, as long as you have a habitat intact, more wind is always better. After all, you literally have a WW2 plane's engine worth of free power in every piece of metal you find or make.
What I am describing is ridiculous. I am not arguing that. But that is the consequences of importing a world changing effects.
I've checked pictures, author draws some ridiculous flying devices with transparent wings, that would be eroded in sand storm instantly. Or would cause extreme load on anchors to not to fly away. Or has to spend extreme amount of energy to fly against the wind with no anchors. And is extremely limited by weight and complexity to keep it flying. I see no use in those. Also people walking by foot at few km/h, where a solid sail would ride at 100km/h is also ridiculous.
Energy in speed difference of wind and sand is extreme and has to be utilized. No reason to fly - cant extract the power this way. Same for boring underground, no energy there either.
Even Avatar's sand people are described better, with their sand vessels. Those would work for extremely low tech, before metallurgy, at tech level of 5000 years ago or so. A wooden sled with a sail, wooden sail in your case.
[Sand people](http://vignette4.wikia.nocookie.net/avatar/images/9/94/Sandbenders_using_a_sand-sailer.png/revision/latest/scale-to-width-down/200?cb=20140404203810)
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Unless you want to deal the wind speeds slightly down, the only solution I see is to build massive sloped berms on both sides of the road to serve as a windbreak (massive like in several tens of meters in height and more then hundred of meters in width, maybe more). Since that is a desert, you do not have a possibility to reinforce those berms with trees and plants. So you would need to use stone blocks or cement to build them.
In general, it seems more like a civilization-wide effort along the lines of Egyptian pyramids or Great Chinese wall, than a fast-profit business venture. It will also need constant maintenance and repair. Manned stations at certain intervals with people being always ready to clean the sand blockages, install and take down temporary screens, etc.
Another idea that may work is a huge 'crawler'. A huge tortoise-like shape, much to massive to be affected by the wind, similar to a medieval siege engine, but several times bigger. Huge wheels, hidden under the shell, a huge number of oxen or similar animals to push it from inside, storage area for the cargo and people. A rocket equation problem comes in play here - whether the oxen are able to move the weight of the shell, cargo, people AND feed for themselves enough to go from one settlement to the next one.
UPD: What I think will NOT work:
* Lighter screens of any type, similar to windbreaks along our automotive roads. I can't imagine a lightweight material that wouldn't just sail away in such a wind.
* Tunnels. Creating a tunnel under the shifting sand in what is, effectively, a constant sandstorm doesn't seem a safe proposition to me. Not only the pressures on the ceiling would be constantly changing, you will also not be able to create a reliable ventilation system for it. Any sort of ventilation channels would get clogged with sand all the time.
* Sailing. The speeds you mention are several times higher then the speeds deemed safe for sailing at sea.
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To protect roads against harmful winds:
* Install [windbreaks](https://en.wikipedia.org/wiki/Windbreak) or shelterbelts along the main roads:
[](https://i.stack.imgur.com/rqs1U.png)
[source](https://www.cosio.co.nz/hort-products/wind-fab)
* Alternatively walls could be used, but they are a lot more cost-intensive.
*The big question usually is who is going to construct and maintain these options, but since it will benefit the economies of all connected participants, it will probably be a profitable investment.*
For the individual solution:
* You can also opt to use all that wind power:
[](https://i.stack.imgur.com/5BWgs.jpg)
[source](https://www.youtube.com/watch?v=97fjOmGg2jc) (video)
You might need something a little more sturdy to withstand the winds in your world, but the principle could be lucrative, if the winds prove to be somewhat reliable.
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If the winds are predictable (to a point) you can try to dig in out int he wild when travelling (and dig yourself out afterwards). Possibly by adding windbreaks to catch blowing sand before it covers your position or by setting yourself up to get covered by sand and having enough air to dig yourself out. Ideally you would travel from safe area to safe area. A desert doesn't have to be dunes, it can contain rock. It could containman-made rocky outcrops like a fort or a large artificial cavern.
If the wind direction is predictable you can have the entrance/exit face a favourable way (allowing ventilation and exiting). If the wind changes day by day having multiple exits (with the open exit changing depending on the wind). it would be a job to uncover the exits every day but with at least 1 exit open at all times.
This would give you small settlements/outposts that need to be manned similarly to stage coaches. They could be supplied (and keep supplies for the return journey) allowing the trader to move much more freely. It is much easier to travel if you're not carrying food and water for yourself, your animals and the return trip.
It might also be good to have navigation mirrors up that reflect the sun. Like a lighthouse. They may need to be defenses against marauders or local animals depending on your world.
If the civilization is old it can be that once it was full of these posts but they have gone into decay. Perhaps some quite impressive old ruins are still in use. If it's an emergent civilization then it could be that they just started building these and the problems that show up (animals, buried, unexpected wind shifts, rains of fish) are still to be encountered.
supply to these posts could be done by a separate entity (this will mean they will charge a toll for people staying) or by themselves (in which case they likely will charge rent for room and board individually).
Perhaps overland travel is being done these days and it is inefficient but one rich trader has read stories of underground tunnels in the rock and is exploring for one of these as it would be very fast indeed and it will mean they don't have to pay a toll. Also they may encounter weird things from the past, unleash an ancient evil, activate ancient machinery or bring about a new age of enlightenment as trade and therefor culture can take a leap
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# Sheltered above-ground walkways
People have been building large stone structures for a very long time. If these people have access to stone, the most straightforward answer is probably for them to build sheltered walkways *above ground*. If stone is not abundant, but they have sand and water, I'd expect them to make bricks (although bricks will probably wear down faster).
These walkways would be built outward from this town toward the next. It might take a long time for walkway construction to reach the next town, but each step of the way is protected by the hallway that's been built up to that point. It will go faster if both towns are able to build toward each other.
If this is a sandy desert, I imagine that the hallways would eventually be covered by sand. This is a good thing, because it protects the structure from the wind. However, it does mean you have to worry about too much weight. For this reason, I would expect covered exits on the leeward side at regular intervals so that staff could climb up top and remove excess sand, and sweep out sand that has gotten into the tunnel.
Tunnel security will be a major concern as thieves seek to prey on shipping. As the Greeks said, "Where there is a sea, there are pirates." I would expect thieves to lurk in the desert near the maintenance exits that are far from town so they can ambush traders. I think this will be worse than historical piracy in the real world (e.g. along the Silk Road), because the only navigable routes in this world are so discrete. So, nobody will build these walkways until they have devised a business model that provides for adequate security. (My guess is that this would have to include a mix of armed escorts, patrols of the walkways, and well-defended security checkpoints at each terminus.)
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I could imagine a ship-like means of transportation in combination with an underground fluidized air bed. (As it can be seen in this video by Mark Rober: <https://www.youtube.com/watch?v=My4RA5I0FKs>)
If the sand is not static but fluid it would *somewhat* behave like water and you could technically use specialized **sand ships** on the fluid sand road.
This - of course - is a huge technical undertaking as it would require every road to have a fluidized air bed. But maybe there are natural ways to induce this by reconnecting underground tunnels. You could use wind power to your advantage if you are able to redirect it underground and then let it blow back up and fluidize the sand. In combination with the sails of the sand ships and the already strong wind this could be possible.
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Worldbuilding, thank you for your time. I came to this site to ask a few questions and get advice, if possible, on a project I'm working on.
I have always been a fan Turok, Dino Crissis, Cage of Eden, and most recently Fosilfuel. So, this project is basically a love letter to the Prehistoric Horror genre.
A year ago, I read a news what said they may have found the degraded remnants of DNA on the bones of a Centrosaurus and a Hypacrosaurus. Aswell about a news about a scientists retrieved a 80-million-year-old dinosaur protein from a fossil. Don’t know if it has been proven or disproven.
But based on that, I'm planning on writing a series of prehistoric horror stories. The setting is based around the concept of cloned dinosaurs from the Madagascar’s Maastrichtian age, the last stage of Late Creastaceous. Through it would be a science fiction story, I still want my history to be grounded that are plausible, to do a soft science-fiction story.
The concept would be about a of natural substance, chemical or plausible natural occurrence what managed to preserve of proteins fragments from fossils of Majungasaurus, and Rapetosaurus what were near each other, possibly a preserved while locked in battle.
A group/organization of geneticist managed to get sufficient amount of preserved genetic material of Majungasaurus, and Rapetosaurus, enough at least for them to use birds and turtles to fill the missing gaps to form complete DNA structures and make a viable clone or at the very least the closest plausible recreation.
To avoid notice, the research is done in an island on the pacific, of 25kmx25km, of a warm, dry (though humid) coastal environment and seasonal rainfalls. Based on the real-world islands of Bonaire and Aruba. Because the prevailing climate of these Dinosaurs environment was semi-arid.
The Majungasaurus was chosen because being one of the last non-avian Dinosaurs what managed to still exist until the the K–Pg extinction. As well one of the better understood theropods.
The dinosaurs are let to inhabit the island, into a stable but isolated ecosystem. And the characters of a ship wreckage, end up trapped in the island.
So, supposing there was a unique substance or natural occurrence what may have helped preserve enough genetic material of the Majungasaurus and others for 66 million years, the questions are:
• What type of substance, chemical or natural occurrence, real or plausible, may help preserve the genetic materials of the Majungasaurus and others of the region for 66 million years, and viable enough to be cloned or closest genetic modified recreation?
Gratefull for any help or advice.
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At this time my money is on [Kilisis' answer](https://worldbuilding.stackexchange.com/users/22207/kilisi) as the most likely real world possibility.
But I do have an alternative very speculative ice based answer for you so here goes.
[Ice Caves.](https://en.wikipedia.org/wiki/Ice_cave)
To keep the DNA usable throughout all that time you probably need to keep it cold.
But the ice caps are only [maybe 45 million years old](https://en.wikipedia.org/wiki/Antarctic_ice_sheet) which won't get you back as far as you need.
Howsoever even when the surface ice is gone we can still expect the poles to be the coldest bits of the planet on average so even when there's no ice on the surface there might still be [permafrost](https://en.wikipedia.org/wiki/Permafrost) & certainly we can expect permafrost to persist longer at the poles than other areas at times there are no ice caps.
Go a little deeper & you might still have ice caves for much of the planets ice cap free periods.
So in this speculation we hope that somewhere in the landmass at the South Pole (there's none at the North Pole) there's a very old ice cave a dinosaur wandered into before it was an ice cave & that the temperature in the cave remained frosty like the [Bandera Ice Cave](https://en.wikipedia.org/wiki/Bandera_Volcano_Ice_Cave) while the ice cap's not there.
[Antarctica back then](https://www.bbcearth.com/news/when-dinosaurs-roamed-antarctica) was more or less on the south pole where it is now so it works on that level.
There are problems with this idea, one of which is why didn't the DNA degrade between the time the dinosaur wandered in & the first ice forms in the cave, you may perhaps have to add something like amber to this picture & have a bit of the dinosaur somehow [trapped in resin](https://www.bbc.co.uk/news/science-environment-51835946) & then somehow find its way into the cave (washed into it by rainwater perhaps).
Another problem could be timing, why would a new ice cave develop that wasn't there before the dinosaur wandered in or a piece of amber with a bit of it in got washed in? well [a big asteroid did hit](https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event) around then & that's going to have thrown a whole load of stuff into the air & caused a global temperature drop which might have been enough to get an ice cave started (& once started they can be remarkably persistent), information on global temperature changes following this impact & on ice cave formation & development from someone knowledgeable would be appreciated here.
[Amber](https://en.wikipedia.org/wiki/Amber) probably won't keep the DNA good on it's own but it should help keep it *better* during the necessary period when there's no ice in this scenario & that might be enough together with cooler temperatures for most of the time to give you usable DNA now, or maybe not, that's the best I can come up with though.
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So you've sealed it in amber away from biological or chemical factors that might degrade it, buried it in a hole shielding it with rock from sunlight & other radiation that might degrade it then frozen it to stop anaerobic activity inside the amber that may degrade it, I don't think we can do any more.
The causes of [DNA half life](https://www.nature.com/articles/nature.2012.11555) has to lie in some combination of those so we should have prevented it.
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Now lets talk about [probability](https://www.youtube.com/watch?v=THSY7-CxKnQ), all of that coming together is a bit unlikely, I think that covers it?
There are other problems with the idea I'm sure but I've addressed all the ones I can see.
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Genetic sequencing is currently moving by leaps and bounds. All it would take is a breakthrough and fossils in a cold cave or something similar I would think.
But currently everything I have read gives DNA viability a million to 7 million years tops. However that's theory, so it's open to interpretation and change.
There is another way though, we can currently see ghost hominid populations featured in our own genomes and even virus DNA from millions of years ago. So we may be able in the future to extrapolate the DNA sequence from dinosaur descendants somehow. The field is fairly new, very well financed and has some brilliant people working in it.
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Aliens did it.
No, really. All you need do is have the remains of an alien exploration camp. Just before the K-Pge extinction, some alien biologists had set up a field camp that had the bad luck to be caught in an landslide, or some other minor natural disaster. The aliens cleaned up and went on their way, so there's no bodies, and most of what remains isn't really useful (some remains of tents that don't have fabrics any more advanced than modern polymers, a few samples of written material that seem to be instructions for their equivalent of a porta-potty, and so on), but one incredibly useful thing has remained: one of the biologists unintentionally left behind the equivalent of a thumb datadrive.
The materials used to build it are extremely durable, which has some potential applications once they're figured out, but the more immediate prize is the data itself: it was stored in binary, and it can be read as the process wasn't too dissimilar to what's used in our SSD. What's been discovered looks to be field notes in the alien language (still in the process of being translated), but the real treasure was what turned out to be images: we have pictures of some wildlife from 66 (or whatever you want) million years ago, and attached to those images are files that were, eventually, recognized as being DNA sequences, probably of the animal in the associated image. And the people working on this realized they now had the entire genome of assorted extinct species.
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The problem with really old DNA is an issue with chemistry. DNA is not really stable over millions of years, because not only the bonds break - the cytosine in the DNA (the C in ACGT) becomes uracil over time, which makes for senseless genes.
If you wish to slow this process down, you need to freeze it.
When the dino killing asteroid hit, bits of the Earth were thrown in to space. Maybe some ambar with mosquitoes in it made it intact, and got surrounded by rocks to protect it from solar wind and UV light. At close to absolute zero DNA should last far longer, and you might just luck it out by finding it in an asteroid.
This may seem far-fetched, but remember, [NASA was looking for signs of life in meteorites from Mars that fell onto the South Pole](https://www2.jpl.nasa.gov/snc/nasa1.html).
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Here's one, but you're not going to like it.
***The DNA isn't that old.***
The problem, as you've noted, is that DNA shouldn't survive millions of years, pretty much no matter what. Neither should *any* soft tissue.
...And yet, we *have* soft tissues. We have *definitive proof* that the Uniformitarian model has flaws. Given that, it's well within willing suspension of belief that viable DNA might be found. (After all, Jurassic Park didn't get hung up on the issue.)
However, there's another model that is also claimed to fit the available evidence, which claims dinosaurs were around as little as a couple *thousand* years ago, not millions: [Young Earth Creationism](https://en.wikipedia.org/wiki/Young_Earth_creationism). Perhaps you could write your story from this perspective, or perhaps you could just have DNA "turn up" and confuse the heck out of the Uniformitarians. It would make for an interesting story and an added layer of conflict to have evidence turn up that seems to soundly refute Uniformitarianism while providing ammunition to YECs.
Taking this idea and running with it doesn't mean your story has to implicitly endorse YEC, either. Maybe aliens have (for reasons which are surely inscrutable) been preserving dinosaurs elsewhere and introducing the odd still-living specimen to Earth every now and then, thus explaining legends of "dragons" and such. Maybe these aliens are even *deliberately* "leading on" YECs (for aforementioned inscrutable reasons). Really, you could have a lot of fun with this, *whichever* way you want to slant it...
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For smelting iron, you need a fuel that's nearly pure carbon, which has typically been either charcoal or coal. The former is the more easily obtained; when the forests were too depleted to provide adequate supplies of charcoal, people started mining coal on a large scale.
Is it actually the case that charcoal is as good as the best coal, so that in a setting where adequate supplies of the former still exist, there would be no reason to start mining the latter, and a setting that was deficient in coal, would only be a hindrance when the forests started running out?
In particular, I noticed in an answer to [How far could civilisation develop within one lifetime - starting from nothing?](https://worldbuilding.stackexchange.com/questions/186953/how-far-could-civilisation-develop-within-one-lifetime-starting-from-nothing?rq=1)
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> anthracite coal. This allows you to fire kilns to a sufficiently high temperature to make steel.
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I would be surprised if that implied anthracite is better than charcoal, which is as I understand it also pretty much pure carbon. But perhaps it just implies 'given that the forests are depleted and you have to switch to coal, you are much better off with anthracite, which is pure enough to fully substitute for charcoal, instead of having to burn something lower grade like lignite'?
[Answer]
As stated in the Wikipedia page for [steel](https://en.wikipedia.org/wiki/Steel)
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> Steel was produced in bloomery furnaces for thousands of years, but its large-scale, industrial use began only after more efficient production methods were devised in the 17th century, with the introduction of the blast furnace and production of crucible steel.
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Quantity is for sure a problem:
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> Since the 17th century, the first step in European steel production has been the smelting of iron ore into pig iron in a blast furnace. Originally employing charcoal, modern methods use coke, which has proven more economical.
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And then it comes also the related temperature problem
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> Crucible steel is steel that has been melted in a crucible rather than having been forged, with the result that it is more homogeneous. Most previous furnaces could not reach high enough temperatures to melt the steel. The early modern crucible steel industry resulted from the invention of Benjamin Huntsman in the 1740s. Blister steel (made as above) was melted in a crucible or in a furnace, and cast (usually) into ingots.
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Same concept is expressed in the page for [charcoal](https://en.wikipedia.org/wiki/Charcoal#Metallurgical_fuel)
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> Charcoal burns at temperatures exceeding 1,100 degrees Celsius (2,010 degrees Fahrenheit).[9] By comparison the melting point of iron is approximately 1,200 to 1,550 °C (2,190 to 2,820 °F). Due to its porosity, it is sensitive to the flow of air and the heat generated can be moderated by controlling the air flow to the fire. For this reason charcoal is still widely used by blacksmiths. Charcoal has been used for the production of iron since Roman times and steel in modern times where it also provided the necessary carbon. Charcoal briquettes can burn up to approximately 1,260 °C (2,300 °F) with a forced air blower forge.
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> In the 16th century, England had to pass laws to prevent the country from becoming completely denuded of trees due to production of iron. In the 19th century charcoal was largely replaced by coke in steel production due to cost.
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I would also add that burning pure carbon produces a much more clean product, reducing less effort in purification, which again goes on the economic side. Also don't forget that to make charcoal you need to process wood, you can't just burn chopped tree. This again adds to the economy of the process.
[Answer]
Charcoal and coal are mostly equivalent though there are two crucial differences:
* Coal often contains Sulphur, which is why charcoal was often preferred until the process for making coke from coal was invented (for brewing beer at first, the use in metallurgy came later)
* Charcoal is far more brittle than coal, making long range transport difficult. What arrives after a bit of shaking along the road is a mix of fine powder and larger chunks.
If you want to imagine an industrialization fueled by charcoal, it should feature huge plantations of fast growing wood with coal kilns in between (check out Hoffman kilns for a rather efficient and almost high tech approach to charcoal making) and pellet presses to process the transported charcoal into solid bricks before burning.
[Answer]
I'm wondering what you are asking and what your ideas are about smelting iron.
[Smelting](https://en.wikipedia.org/wiki/Smelting) "*is a process of applying heat to ore in order to extract a base metal*". Iron is a base metal.
Charcoal may have been used in the past to heat iron ore, but these days other sources of heat are used, depending on the facility used: coal, gas or electricity.
The thing about using charcoal or coal in smelting iron and making steel is they have had two uses: firstly to heat the ore and secondly to remove impurities within the ore to leave the metal required.
[Iron ore](https://en.wikipedia.org/wiki/Iron_ore) is various forms of iron oxide: magnetite (Fe3O4, 72.4% Fe), hematite (Fe2O3, 69.9% Fe), goethite (FeO(OH), 62.9% Fe), limonite (FeO(OH)·n(H2O), 55% Fe) or siderite (FeCO3, 48.2% Fe).
In the smelting process, carbon is used to remove the oxygen and leave behind the iron metal. When the iron ore is being heated, by whatever means, carbon is added to the molten mix to reduce the iron ore, produce iron metal as the desired product.
[Charcoal](https://en.wikipedia.org/wiki/Charcoal) is a good source of carbon because it is made from partially burnt wood and it has had some of the impurities from the wood removed during the burning process in a oxygen reduced environment.
The current day substitute for charcoal is [coke](https://en.wikipedia.org/wiki/Coke_(fuel)). In the same way that charcoal is partially burnt wood, coke is partially burnt oil or coal.
This is added to the iron ore melt. It reacts with the molten iron oxides. Oxygen from the oxides bond with the carbon in the coke (charcoal in older applications) to produce carbon dioxide (CO2), leaving behind molten iron metal.
When it comes to reducing the iron oxides during smelting, coke from coal is not inferior to charcoal from wood.
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[Question]
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I'm building a world in whose history climactic changes causes a region of desert to start seeing regular rain. This causes the native culture of the desert people to also change along with it, eventually evolving to something akin to the Mongols and finally the Yuan dynasty of China. (Essentially moving from a desert nomad to steppe nomad culture, and finally becoming a full fledged settled civilisation.)
My research shows that this scenario has parallels to the African humid period, where a stronger West African monsoon caused a greening of the Sahara. But nowhere is it mentioned **how long** it took for the desert to turn green.
My question therefore, is this:
1. Provided monsoon conditions of the strength we see in the Indian monsoon system, how long would it take a desert region approximately half the area of the Sahara to turn green?
2. What would be the steps involved in this process?
3. If a hypothetical bordering empire (with technology akin to the Chinese Tang dynasty or the Sassanids) were to conquer the region during this period of "greenification", what strategies could they use to assist in speeding up the process?
Any help would be highly appreciated!
[Answer]
Areas of the Sahara desert do turn somewhat green after heavy thunder storms which happen occasionally. Within days the desert is in flower.
But with massive quantities of regular rain there would be plants everywhere before long.
Initially there would be plenty of low growing desert flowering plants, cacti and shrubs limited by the amount of nutrients available. But this would attract birds, insects and other animals from peripheral areas creating a thicker cover of vegetation starting from the peripheral areas and working in towards the deeper areas of desert.
**This all assumes vast quantities of rain. With less rain less regularly the process might not get started at all or could take any amount of time you desire depending on quantity and frequency.**
But with regular heavy rain the main limiting factor would be the availability of nutrients. It would take a long time to establish trees, but within decades the more mobile seeded species could start to appear everywhere carried but birds and the wind.
Concerning speeding up the process, this would depend on the new people being aware of what was happening and the exact amount of rain and its distribution. Assuming they were aware by some means and the rain was less than Amazonian then standard arid land management should be effective.
This involves channeling water run off into a series of plant growing areas with one overflowing into another and by capturing water below ground by use of many small barriers and dams can help prevent rapid water run off. Measures to prevent people chopping down trees for firewood would be needed as well as growing the right crops.
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It really does depend massively on how much rain there is both in volume and frequency. With constant regular rain it could tend towards the Amazon encouraging rapid forestation with a massive river system(s) developing from the get go.
With a very wet season and very dry season you could end up something like southern Madagascar with huge rivers such as the Mandrare river (a 400m wide winterbourne) gallery forests around the rivers and drought tolerant thorny forest (or equivalent) elsewhere.
[](https://i.stack.imgur.com/o9s0k.jpg)
With less regular and/or more modest rain fall many other climatic types would be possible for example any climate type from the bottom of this diagram: <https://www.climate.gov/file/holdridge-lifezonespng>
[Answer]
I want to expand a bit on Slarty's answer.
First, I'd like to second his emphasis on just how much rainfall you'd need; it's much more than you'd think. Something that most people don't realize is just how much water there actually is in soil. One of the primary reasons that deserts get so hot in the day, and so cold at night is actually because there is no water in the soil. It's just like how being close the the ocean moderates the climate of a region, because the immense thermal mass of the ocean slows down the temperature fluctuation. Well, the large amount of water in the soil actually does the same thing; although not quite as strong as the ocean. The thermal mass of water is huge, compared to most materials. Water has a specific heat capacity of 4,182 J/Kg C, while quartz sand is only [830 J/Kg C](https://www.engineeringtoolbox.com/specific-heat-capacity-d_391.html). Check out [this video](https://www.youtube.com/watch?v=NGzcvarmZgk) of a gardener reviving dry soil; he's not quite starting with completely dead sand, but it should give you a better idea of just how much water is needed.
Secondly, as far as what humans can do to accelerate the de-desertification, again, the primary objective should be retaining water. Extremely dry soil, actually has the counterintuitive property of being hydrophobic (i.e. it repels water). So, in areas with very dry soil, you may get a monsoon, but the extreme vast majority of that water will just skim across the surface, and virtually none of it will get absorbed. What you need is either frequent soft rains, or something to get the water to stagnate ([or at least slow down](https://www.youtube.com/watch?v=-4OBcRHX1Bc)) over the land, to give it a chance to soak through the initial hydrophobic property of the dust, and get into the soil. And even once you have gotten some water into the soil, you need to keep it there. If the air is very dry, it will suck the water out of the soil, and all that water will evaporate and be lost again. Biochar is a very effective method of retaining water in soil, and it can even be done with extremely primitive technology (ex: clay or dirt mounds on top of a wood pile). Basically, you just burn or heat up wood, in a container with zero or minimal oxygen, and it turns into charcoal, but the microscopic structure of the wood is retained, which produces tiny little pockets with immense surface area. You grind the charcoal up into the consistency of sand or smaller, and mix it in with the soil. All these tiny particles act like little sponges, and protect the water from evaporation, thus allowing soil to retain water far longer than normal. Also, biochar has profound benefits for soil health, as it gives micro organisms a safe place to hide, and it can retain soil nutrients to prevent them from being washed out of the soil. When combined with things like rock dust (either natural, as would be present in dessert dust, or manufactured), it can significantly increase the long term health & productivity of the soil, as well as the speed at which a soil can regrow fertility. There are several ancient sites across the world, where peoples were using biochar thousands of years ago. You don't necessarily have to know the science in order to discover that it works.
After water, the biggest thing is getting organic material back into the "soil". A desert has been bone dry for so long, that basically all of the organic matter has turned to dust, and either blown away or broken down into sand and trace minerals. Most plants don't like growing in sand; they need the protection & symbiotic environment of soil, which is largely defined by the presence of organic matter. When you're doing this on a large scale, you really want to get nature to do most of the work for you, so you want to set up the conditions for the ecosystem to build the soil & organic matter for you. One way to do this, is planting trees that are hardy enough to survive the initial harsh environment. If you can get them to survive, their roots will push sugars into the soil to cultivate fungus & bacteria who in turn process the raw minerals and make them available to the root systems. Once you have enough water in the soil, these fungus & bacteria can begin breaking down raw organic matter into soil. [China is currently using this strategy to stop "the yellow dragon"](https://www.youtube.com/watch?v=pSn6S-H7m-8), a region of desertification that is spreading rapidly across China.
To help this process along, you can bring in organic matter to jump start this process. There are 2 ways to do this:
1. On a small scale, you can bring in compost and mix it in with the native dirt. When combined with the introduction of water (and optionally biochar) this has the benefit of instantly boosting the fertility of the soil to that of semi-high grade soil (depending upon how much compost you put in), that is immediately ready for growing growing crops or high-grade vegetation. This could be appropriate for outposts, or oasis scattered throughout the area to serve as introduction sites for worms & animal species, which will eventually be required for full restoration, to speed up their migration into the new ecosystem. However, compost takes time & manpower to produce, so a cheaper alternative would be to mix raw manure into the native soil; as seen in the gardener video I referenced earlier. This has the same benefits of boosting organic matter, and speeding up the restoration process, however, especially if you're mixing it with the raw sand of a desert, it will require time to decompose (with sufficient hydration & bacterial life), before it becomes high-grade soil.
2. On large scales this amount of work becomes infeasible, unless you have the cultural incentive, financial capacity, or dictatorial authority to command the necessary manpower. An alternative would be widespread mulching. Covering the surface of the ground in wood chips or straw around 1 foot deep. This acts in two ways: First, it acts as a form of water retention, as the top layer of mulch protects the bottom layer from sunlight, and partially insulates it from heat & wind which would accelerate evaporation. Second, the mulch acts as a source of organic matter. With sufficient water & fungal spores, the mulch will rot into a good quality soil. But to maintain this soil, you either require consistent application of mulch until the ecosystem is stabilized enough for planting, or biochar & hardy vegetation to stabilize it. Also, on large scales like this, of trying to transform an entire desert, none of this stuff has to be perfect. So, just going through vast areas, and spreading a 1 inch layer of biochar, with as much manure as you have access to, scattered over it, and covering that with a 1 or 2 foot thick layer of mulch (wood chips, straw, wheat stalks, etc.), with a grid of trees planted every 10 or 20 feet, would be fine, and would drastically accelerate restoration of the area. The fungal mycelium, and worms, will take care of spreading everything out & mixing it up.
Finally, another thing to keep in mind, is that once you have done this on a large enough scale, the presence of plants (especially trees), [actually starts to produce more rain](https://www.youtube.com/watch?v=Y3OWgb0Bv-A).
[Answer]
Just a tidbit that might be helpful: beavers can green a landscape !
Beavers protect themselves from predators by modifying their environment. By damming small watercourses, they create large pools of water that they can hide in to reach further food sources. They also dig channels at the bottom of these pools as they repeatedly swim the same route. All of this creates deep reservoirs of water and wetlands which can weather droughts where a seasonal stream would dry up, allowing more vegetation year-round. This has the potential to create a chain reaction in a watershed. The new ecosystems would also present new food opportunities for cultures in the vicinity.
I can't find the exact video I saw on the subject that really made it click for me, but [here's a nice outline](https://www.youtube.com/watch?v=iyNA62FrKCE&t=1s&ab_channel=BBCEarth) of beaver lodge construction and a vid on [beavers' effect on desert](https://www.youtube.com/watch?v=_23vuRU2Ews&ab_channel=GrandCanyonTrust).
If your world has the same animals as earth, you could consider adding in beavers as a passive regreening process. Or, you could even draw up some other fauna that have similar effects.
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[Question]
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*This question is inspired by a [comment](https://worldbuilding.stackexchange.com/questions/192273/what-would-cause-creatures-on-a-planet-to-favor-large-sizes-over-small-sizes/192287?noredirect=1#comment596088_192287) by PcMan*
Imagine you have an Earth-like planet, except it is just a little farther away and has longer days. Instead of having a tropical equator, the planet now has a temperate equator with extremely cold latitudes. The planet has a day 16 times longer than our Earth's, so there are periods of day and night that last over two weeks. At night time, the temperature would be below freezing, far too cold for detritivorous insects.
Therefore, the insects would only thrive/breed during the long daytime, and die off during the night. The decomposing bodies would be plenty of food for night-time fungi.
In theory, fungal forests would be a plausible alternative to the insects at night, where they would wax in population at night and wane in the day. I define a fungal forest as a dense collection of fungi organisms. This would be in the form of decomposing animals and plants, such as bodies or rotting tree trunks.
**Are seasonal fungal forests like this possible?**
[Answer]
**What Do The Mushrooms Eat?**
It's important to remember that fungi are heterotrophes. Like animals, they must get their energy by consuming other organisms. Forests are typically made up of trees, which are autotrophes: they can make their own food from the sun.
Most fungi eat decomposing plant matter. Most of the mushrooms you might be familiar with at the grocery store begin life as a spore that has landed on some dead plant stuff, either a log, a pile of leaves or straw, or else commercial grow media. The spore grows into a network of myclium that consumes the plant matter, and when the fungus has had its fill, it fruits mushrooms which spread more spores and then often dies of starvation, having completely exhausted its food supply. A log that has been eaten by fungus cannot even be used as fuel, it is so thoroughly consumed.
For your mushroom forest, you will need to explain where all of these massive mushrooms are getting their food from. This could be an opportunity to add some additional ecosystem elements to your world! Perhaps some vast horde of migrating animals seasonally comes to this forest to procreate and die, leaving their corpses to be consumed by the mushroom trees. Or maybe they just come here to poop - before carrier pigeons went extinct, they used to blanket [tree-filled] forests with so much shit that you can tell what years they migrated over a particular area just by looking at the growth spurt in tree rings.
**Prototaxities: Real World Fungus Forests (maybe)**
400 million years ago, there were likely no plants taller than 1 meter. Plants had not yet evolve the ability to make lignin, so they were structurally limited. And yet the fossil record shows evidence of large, trunk-like organisms that grew upwards of 8 meters! These are the prototaxities, and they are thought to have been fungus. It seems they did indeed grow as a [sort of forest](https://i.pinimg.com/564x/b0/bc/ec/b0bcecf8d1ae554302e6581b75f37025.jpg) (sometimes) (maybe). What did they eat? That seems to be a heavily disputed issue. One prominent theory suggests they had a symbiotic relationship with algae, which might have provided photosynthetic energy. However, symbiotic relationships between algae and fungi are usually called "lichen", not "mushroom".
**A Final Suggestion**
Speaking of millions of years ago, when plants eventually *did* evolve the ability to make lignin, it sparked a global extinction event. At first, few if any organisms on earth were capable of breaking lignin apart, so as plants died there was no one around to decompose them. These dead plants piled up everywhere, refusing to yield their carbon back to the atmosphere and sparking a horrific climate catastrophe. I imagine that whichever organisms first evolved the ability to break lignin apart must have really gorged themselves though! Maybe this could be the case for your mushroom forest: a mega-huge mushroom species discovered an ancient, buried forest and now feeds on millions of years worth of preserved wood. Just a thought!
[Answer]
**Fungi don't like the cold either.**
On your world it is below freezing at night and too cold for bugs. That is cold for all water based life. Fungi too will power down when it is below freezing. I am reminded of the stories of Shackleton's hut in the antarctic, preserved in the cold for decades until recently.
<https://www.chicagotribune.com/nation-world/chi-huts_mainjul02-story.html>
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> For 90 years the dog's carcass remained where it fell, a collar and
> chain still around its neck. For most of that time much of the flesh
> and fur remained intact, preserved by Antarctica's extreme cold. And
> though gale-force winds have beaten ice, snow and sea salt into the
> sides of the hut, the foodstuffs inside remained intact.
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> Now it appears a changing climate is threatening the history housed in
> these huts at the far end of the world, simple structures that many
> place among the greatest monuments to courage and the human longing
> for discovery.
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> With the weather warming on Ross Island, mold and fungi are blooming
> in all three of the explorers' huts -- some so mysterious scientists
> don't know what they are. They are rotting the timber of the huts and
> thousands of artifacts inside them. The dog is now reduced mostly to a
> skeleton.
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A fungus forest is a fine idea but I don't think it will like it below freezing any more than the bugs.
[Answer]
Yes, they'd be possible. Mushrooms grow their fruiting bodies remarkably quickly and could definitely do so in the 8 day-long period of sunlight/moonlight. Of note, you wouldn't have massive mushrooms, though. They wouldn't replace trees; there would just be more of them! Also of note, the majority of a mushroom is the mycelium which is hidden below ground, so that may be much more prominent in your world. I would also add that insects are a major contributor to biomass and are a prime thing that mushrooms (and other decomposers) decompose as well as a major source of food for secondary consumers. There would have to be something to replace them or else the ecosystem just wouldn't work.
[Answer]
like the ones in mincraft, well, the answer is yes, they could start growing in spring, and die away from cold in winter, but they need enrgy, this energy is transported by mycelium networks, but where does it come from? well, other forests, maybe animals, etc, this problem i have not been able to solve, maybe they evolved some kind of chlorophyl? or eat the poop of insects and other animals?, another thing would be the growthrate, which is very plausible, as seen in other mushroom, the stability can change depending on what the networks feed the mushroom, also, it would more likely be a hivemind of mushrooms
or not so big a mushroom, yes to, but these would need other compounds an example could be in <https://criticalconcrete.com/building-with-mushrooms/> , here it gives an example of heat insulator, so the mushroom can trap the heat inside itself and survive
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[Question]
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We all know the ideas about the "ideal zombie shelter" stocked with food, water, and ridiculous amounts of ammunition, hidden somewhere up in the Rocky mountains far from cities. But what about Suburbia? What items that one could reasonably expect to be in an upper-middle-class home would be most helpful in a zombie apocalypse scenario?
For this, assume zombies in the World War Z vein (spread virus by biting, not overly intelligent, but decently fast). Our family lives in White Picket Fence House #31 in The Suburbs. At 6 pm one evening, the news reports the apocalypse is starting, although not yet in full swing. The family of four (two teenage kids) have an hour to grab everything they can cram into their minivan before hightailing it to Grandpa's cabin in the mountains, about an eight hour drive away. What do they grab? (Additionally, is there anything they might not have but would be worth the ten minute drive to the local hardware store to obtain? Society hasn't completely broken down yet, so the roads/stores are somewhat usable for the next 12 to 16 hours.)
Note: it's reasonable to expect that they might have some sort of prep, especially given that we seem to be living in the end of the world already. But this isn't a military family, and the extent of their specific prep for disaster AT MOST would likely be a mediocre "bug out bag", and probably a couple of firearms.
Edit: I am primarily looking for what sort of "normal" household items would be useful.
[Answer]
(I live in a small town, basing the answer on what I got in my garage)
Simple gardening tools would already be helpful. Why? Zombies are melee combatants who are easy to kill due to them not defending themselves properly but also able to take you out in a single hit. So fighting them at a distance is preferable using shield and polearms.
Break a hedge scissors in two, strap them to the poles of some rakes and you got two effective easy to make spears. Shovels are good for digging...because zombies are as many stated stupid...it will take some time but if you can dig a trench around your safe zone they will probably run in one by one, get stuck and then it's just a matter of poking them down safely.
A small box of nails, a hammer and a saw are also something you don't want to underestimate because the power to repair your weapons/home or construct traps/additional fortifications is a lifesaver in the long run. Don't waste time and space on power tools, seeing electricity won't be reliable and the noise is pretty much a lunch bell. Best is to go full medieval on them.
Something that might be unconventional but also useful, the lids of some trashcans. Both he plastic and metal versions are light weight rather sturdy and sometimes come with built in handles, if not they can be added.
Reason for that is that a normal person person would not able to punch through it so zombies would logically lack the same strength. This would again come to play with the whole Shield and spear doctrine I am advising.
[Answer]
Assuming you have everything in the [BOB checklist](https://unchartedsupplyco.com/blogs/news/bug-out-bag-checklist) in your bug out bag, and you're running so far away from society that you are unlikely to see zombies for a very long time (and have firearms for when you do). I'd suggest food and water is going to be a problem before the zombies do.
Hopefully grandpas cabin has a water tank and downpipes. You may wish to buy a water filtration system for it with your last purchase. Otherwise I'd be buying seeds for fast growing year-round veggies that grow in your local climate. Live chickens if you can get them (turns grass into eggs!) And perhaps a solar powered pump to pump water from the nearby creek up into your veggie patch.
If there already is lots of food and water there, my last purchase at the hardware store would be a few [rolls of barbed wire](https://www.bunnings.com.au/whites-1-57mm-x-30m-high-tensile-barbed-wire_p3060467), [a solar powered electric fence energiser](https://www.bunnings.com.au/o-briens-electric-fencing-solar-energizer_p3041517), and a few big fence posts. Many of those electric fences play a tone when zapping, allowing them to double as proximity sensors so you can gun down any that make it past.
After your edit saying the BOB bag is mediocre: Handheld tools. Shovels. Axes. screwdrivers. Hammer. Nails. Files. Chisels. If you're organised enough to keep your tools in a toolkit take your whole damn toolkit. Everything in your garage that doesn't plug into a wall socket is going to be useful. If not as an improvised weapon it allows you to create other useful things.
[Answer]
### Source of fire
Matches. Blowtorch. Cigarette lighters. Something. Anything.
### Carpentry tools
You're going to spend a lot of time channeling your inner Mythbuster or A-Team fanboy/girlism. A cabin without a secure perimeter will get you killed.
### First aid and sanitary supplies
Bleach and Everclear will be your friends. Antibiotic ointment is also a big deal. Sterile gauze, band aids, over the counter finger splints, and in general over the counter medication will be very useful.
### Nonperishable food
Needs no explanation.
### Printouts of Internet how-to guides
The internet contains a wealth of information that will very rapidly disappear. How-to carpentry-for-dummies videos. Text describing how the ren-faire reenactors and doomsday preppers make handmade stuff. You'll be glad to have what little you'll be able to save.
### Windup alarm clocks
Zombies are stupid and easily distracted, especially by loud noises. Set the alarm a few minutes into the future, wind it up, throw it far away from you.
### Hunting stuff
Gear, like a bow and arrow. A how-to guide for how to fletch your own crossbow bolts. *Dressing an animal for slaughter for idiots: A reference for the rest of us*.
### Ways to communicate and attract attention
Battery-powered megaphones. Battery-powered walkie-talkies. Road flares. CB radios, if you have a generator.
### Scrap metal
Let your inner MacGuyver go nuts. The more scrap metal you have, the crazier the stuff you can build.
[Answer]
I would think the primary thing not commonly in a bug-out bag would be unpowered tools of all types: construction, gardening, and camping, e.g. saws, hammers, nails, shovels, axes, hoes, etc. There's a cabin perhaps but they'll still need to maintain it, erect fortifications, dig latrines/wells/etc., build additional structures, gather firewood and other natural resources, do farming, if they're planning on that, etc. Multiple of each is mandatory since they'll be using them hard and there's no way to replace them if they break; anything they have access to in the suburbs is likely to be meant for casual gardening, not heavy use.
[Answer]
**Plywood, for windows.**
[](https://i.stack.imgur.com/yb9bN.jpg)
<https://www.sacbee.com/news/california/fires/article229547469.html>
Depicted: traffic jam of people trying to evacuate the Camp Fire in 2019. Once this is on the news it will be too late to get out of town. It will be too late to go to the stores. Both WWZ and Walking Dead had memorable images of the giant traffic jams that resulted from people trying to flee the cities. They are more likely to get shot by other citizens than they are eaten by zombies.
These folks need to board up their windows or cover them with foil or sheets, and keep quiet. If this happened in my house, I have some big trash bags. I would fill them with water while the water was on. I could make it to PetSmart on foot from here. We would all go and would bring back all the kibble we could carry. The fancy stuff, now.
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[Question]
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Having a weapon attached to your arm that restricts the use of your hand is a common design trope in sci-fi-themed video games, such as Mega Man or Metroid. They even appear in the Marvel movies sometimes. **But could such a cannon ever be more practical than just carrying a gun?** In other words, what assumptions would you have to make about the world, the wielder, or the use case in order for an arm cannon to be the best choice of weapon?
For the purpose of this question, assume that:
* By "arm cannon", I mean a weapon that encloses or replaces a humanoid forearm and fires deadly projectiles.
* The arm cannon should be reliable enough to graduate from an R&D lab. It doesn't need to be cheap or mass-produced, but it needs to be useful.
* The user should still be fairly agile. If mobility was not a concern, they could just mount a turret.
* It can do other things (like serve as a replacement hand) if you want it to, but it's not a requirement.
* The extent that an arm cannon inhibits or requires normal use of the hand is unspecified. Perhaps the arm cannon relies on deft hand motions to operate, or it might even replace the arm entirely.
* The means by which an arm cannon is equipped or unequipped (if at all) is unspecified. Maybe it slips on like a glove at will, or maybe it's part of a larger exoskeleton that takes an hour to put on. Don't forget about mobility.
* The nature of the user is unspecified. Maybe an arm cannon wouldn't be practical for humans, but it'd be fine for humanoid robots that normally use hands, or some humanoid alien with more convenient biology.
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Sounds like you mostly covered the bases in the bullet points. But I'll give you my take on it. The first two are unlikely uses, and the third is what I think is it's most practical usage.
**Prosthetic Arm Weapon (Least Practical)**
Now if you were in a culture where making a fully functional prosthetic hand is not possible, and you are going into battle, you might as well weaponize it, as was done occasionally throughout history. For inspiration, the patta is a historical gauntlet-sword that turns the blade into an extension of the arm. BUT, in a high tech sci-fi setting this seems unnecessary. The prosthetic technology would likely be advanced enough to allow for a hand which is more multipurpose.
**Non Human Users (Maybe Practical)**
Now the main problem is twofold. One, an arm cannon is hard to aim, because we can't naturally look down our forearms very easily. Two, a cannon covering the arm or hand is a bit of an issue because hands are very useful, and we only have two.
Perhaps you have an alien with double jointed limbs that has no trouble aiming down the sights of such a weapon. Or perhaps they have four limbs and have arms to spare. One less thing to drop, I guess.
**Arm Mounted Backup Weapon (Most Practical)**
Here's where I think it could shine. Now there is a caveat, that I think it should be arm or wrist mounted rather than covering the hand, because the hand is just too important and versatile to monopolize like that.
But should you need a quick, instinctual point and shoot weapon - going about your tasks, or you lost your main weapon, what could be quicker than having one mounted on your arm?
You could make it melee capable as well, perhaps with a laser sight if you wanted. That, I think, would be the best use. Not as a main weapon or armament, but as a quick and intuitive backup weapon that's always handy.
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the biggest advantage of a weapon firmly attached to it's owner over one held in hand is that a weapon typically does not care who owns or holds it.
That means, if i manage to take away your pistol, i can aim it at you.
So, a weapon that cannot be taken away has great advantages.
And then there is, of course, the fact that something that is firmly attached to my body is always with me. Maybe you've seen pulp fiction, and remember the scene where John Travolta leaves his weapon on the kitchen counter to go to the toilet? That mistake won't happen if your weapon is attached to you.
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There is real life [Sedgley OSS .38](https://en.wikipedia.org/wiki/Sedgley_OSS_.38) pistol used during WW2. Actually, its a glove with pistol attached to it. It fits into `weapon that encloses or replaces a humanoid forearm and fires deadly projectiles.` It was meant as a covert operations and assassination weapon in the Pacific Theater. It had low accuracy and was realy hard to aim, but during trench combat it could work as "one punch - one shot - one kill" weapon. So, arm cannon can be practical as concealed weapon, during close quarters combat to improve melee strikes.
[](https://i.stack.imgur.com/rtroN.jpg)
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**Aiming the gun**
With a conventional firearm, the shooter aligns the eye, the sights on the weapon, and the target. The weapon is held in one or both hands. Counting the shoulder, there are **three joints** to get into a comfortable and secure hold. With a forearm-mounted gun, there are only **two joints**, shoulder and ellbow. This could lead to a less comfortable shooting stance.
Take a pencil and a bit of tape and tape the pencil first on your index finger, then on your forearm. Try to peer along the full length of the pencil with one eye. Which is more comfortable?
*This could be overcome with electronic sights and a head-up display.*
**Fixing the gun**
For changing magazines, clearing jams, and the like, the weapon is not held in the shooting stance. Both hands can be used on the conventional gun. With a forearm-mounted weapon, there is only one hand, the other is permanently fixed where it cannot reach the gun.
*This could be overcome if there are no user-serviceable parts inside, e.g. a futuristic laser weapon or railgun.*
[Answer]
It could work, and many answers have stated some solid pros and cons.
A solid Pro would be that you are armed at all times. Another is the element of surprise, "Aha, you thought I had nothing but now I have a gun at your head". But there are some major cons to what you may have seen in these guns from Comics and Video Games.
If you must have a forearm type prosthetic slug thrower, you have to consider some things.
Ammunition loading. Remember that rounds don't magically appear in the chamber. You have to load the weapon, and you have to do it with one hand, so you have to account for that.
Ammunition size effects lots of things. The bigger the round and powder charge, the more robust the mechanism and barrel must be. That means size. If you don't want a Popeye like forearm, this has to be taken into account.
Recoil. This is a big one. When you fire a normal rifle or pistol, the recoil normally impacts the shoulder or the wrist, both of which can distribute the force in lots of little ways. A forearm gun is going to go right into the bones of the forearm. Most automatics are therefore going to pound the heck out of the stump, possible causing stress fractures and other trauma. Recoil charts are available, but just consider Newtons third law and *ke=1/2 mv^2* if you are looking for something futuristic.
Heat. Where will the heat go? You tube has videos of people cooking bacon on the barrel of an ak-47 or other rifles. I know my own bolt action rifle (.308 Winchester) gets too hot to touch after shooting 20 rounds, and that is with stopping to reload every 5 rounds, one round at a time with a pretty long pause between shots. So you have to account for heat.
Here is the solution though. A Cannon is probably out for the above reasons, but you could theoretically put a good .25 Magnum round weapon in a forearm prosthetic. The rounds are small enough where you could load several without looking like Popeye. The mechanism is fairly small, so could be concealable. Kel Tech weapons makes a neat little .25 which is the same size as an ordinary pistol, but can hold 30 rounds in a small magazine. So you get a very small form factor that can be hidden, and a surprise weapon that is effective.
That will give you the best bang for your buck.
*(so sorry for the pun. I couldn't help it. I have a problem)*
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I don't understand the problem. There seem to be so many solutions.
* In a sci-fi setting, you wouldn't let a human control a spaceship. This
would be done by an AI that is far more intelligent and technically
skilled. The same would be with shooting and pretty much anything
else where stakes are high. Humans suck at it, don't let them do it. There would probably be a special interface for the human. He could look at people, see their name, status, power level, etc, see if the person carried a weapon and either confirm the kill or mark him/her as unimportant.
* Have the canon arm defend or surveil its user no matter if he wants it or not, as protection or punishment. The human would have to fight against his arm at some point. He'd purposefully crush it with a car or something like that. This may already be a cliché, but I really like it.
* Maybe you also don't want people to know that you have a gun.
That's why it's built into your prosthetic.
* Make some shit up and explain it with 'people being crazy'. It's not that hard.
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I suspect it's only practical for
* concealment in a prosthetic
* training individuals or troops to understand it as being part of their role in society
One who has had their arm replaced with a gun (especially at a young age) without option to choose or have it removed will be sure to understand that they are and have always been meant to harm.
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The thing is: it's not practical *for you*.
Nobody in his right mind wants to lose a hand. Yet, in some extreme contexts, it could make sense. You're a convicted criminal condemned to mine the moon? Enjoy your new personal mining tool.
You're a cyborg grown in a vat to only ever know war and killing fields? I'm sure that the hand cannon is as close to you as a samurai's sword to it's weaboo.
You're exceptionally determined to be the best quantum mechanic in the fleet? Those freakish hands which let you manipulate force fields will come in handy.
Well, there's a thing you mentioned: the cannon *could* serve as a replacement hand. That's important, because now we have two new crowds:
1. Amputees: most people without a hand will accept to wear a hand cannon if they regain a hand as a side-effect. I know I would.
2. Elite troops/spies/mercenaries: ever played Shadowrun or the like? Watch some cyberpunk and you'll see heavily augmented people. If the hand cannon doesn't make you *lose* the hand, people who want to gear up may just think that it's a great deal.
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If you mean something to keep always attached to your arm it will never be practical. Even if the weapon will be very light the weight would be felt over a long time, the arm is a long lever and the oscillations would be on a relatively long arc.
What would happen is that walking for a long time, paying a lot of attention to the external dangers rather than the own sensations, it could eventually cause some nausea because of the altered balance.
Another problem is that the arm may get tired, the soldier cannot choose when he in the mood for fighting and when he isn't. So he may find himself with the movements and the reaction times slowed down at the wrong time.
If instead you mean something that can be easily attached/detached it would make sense if the soldier has a lot of tools like remote controls for companion drones, special sensors, other weapons and so on.
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To be honest, I love the idea of arm/forearm-mounted guns, but they wouldn't really work, not in the way sci-fi sees them. I see them working like this:
"Rats, there goes my handheld gun, now I am weaponless and the enemy knows it. But am I really weaponless? No, I have an arm-gun the opponent doesn't know about, so I can still kinda fight."
Serving as a backup weapon that is VERY easily concealed, and you don't need a prosthetic.
The whole aiming problem could be solved by having a sub-computer calculate small adjustments that your hand normally would. As for heat, IDK about that. Reloading could be solved by simply having a reloading system that only really needs one hand.
Thats my take on it
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**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
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You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49).
Closed 3 years ago.
[Improve this question](/posts/160777/edit)
An alien spaceship opened a wormhole to a location in near-Earth orbit just long enough for a ship to come through. The ship intended to make public, peaceful contact with Earth upon arrival, but experienced trouble in transit such that it's passengers were using the escape pods immediately after exiting the wormhole. The abandoned ship fell to Earth over the next few minutes.
In the story that I'm writing, only a few parties noticed the ship falling to Earth: namely, a handful of major world governments. **What would have prevented many people on Earth have seen the shuttle fall, and making it public news?** It's a few hundred meters long, so my understanding is that any lucky person with a decent telescope should have been able to see it, especially as it crashed down.
I'm willing to accept that the escape pods might be unnoticed thanks to some kind of alien stealth (if you have to emergency eject, chances are you also want to hide where you're going from someone). However, the original ship was definitely *not* using any kind of stealth.
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## Something else happened that day and nobody was looking there
Years ago, there was an important earthquake in Indonesia (of magnitude 6,5). About 10 confirmed deaths and thousands of houses, schools and buildings destroyed. It was one of the ten stronger earthquakes that year. Yet no media covered it. Why? It happened on september 11, 2001 *(1)*.
A lot of other stuff happened that day, but it was obscured by one single event of such importance that to this day, it is nearly impossible to find sources about any of these others events. Ever heard about the Organization of American States voting for the Inter-American Democratic Charter? Well, whatever it was, it happened that day too.
Our planet is full of people. People do things all the time. If your alien spaceship crashed the same day as the Superbowl, the death of the Pope or the Space Shuttle Disaster, then media coverage would probably brush it as *"Another UFO spotted in Indiana: no one cares"*.
*(1): to be honest, the real earthquake happened on september 5, the one on september 11 was merely a replica.*
## And now for something different: The Kryponian solution
Another reason could be: whatever exited the wormhole, it was not the *only thing*.
In many iterations of *Superman*, Lex Luthor discovers that Superman traveled from Krypton in a pod, along with the debris of his planet that fell on Earth at the same time as he did. In the TV series *Smallville*, these asteroids crash on the eponymous city and baby superman's pod just happens to be one of them.
So the "trouble in transit" could be debris dragged by the ship along the vortex, or the spaceship colliding with unexpected asteroids on exiting the wormhole. At this point, the spaceship is no longer the only thing falling on earth: it is accompanied by hundreds or thousands of [bolides](https://en.wikipedia.org/wiki/Bolide) and, although perfectly visible, goes completely unnoticed because it is now a needle in a haystack (and the haystack is on fire).
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Earth is still mostly an empty planet.
Wast stretches of ocean and entire continents like Antarctica have virtually no observers. If spaceship appeared over an unpopulated area and descended to the surface without crossing over any populated area, its appearance and demise would be unnoticed.
However, if it would be flying through Earth atmosphere without gradually disintegrating, i.e. making a big "boom" either at altitude, or at landing/splashdown, this effect would be noticed regionally or even globally. So to go down unnoticed, the ship should burn down smoothly when falling to Earth.
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**The spacecraft is the size of a walnut.**
It was not noticed because it is small. Many such tiny objects crash into the Earth; some make it all the way down and hit the surface. They are meterorites. Persons watching the sky might have seen this spacecraft glow on entering the atmosphere and assumed it was a meteorite.
Those who were aware of its true nature might have other methods for watching things near earth, or perhaps the angular sides of the spacecraft have a non-meteorite radar profile that gave it away.
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There is the possibility present of the ship crashing and entering atmosphere over a deserted area. That being said, the ship could be accompanied by whatever caused the trouble, as kikirex stated. If it entered over populated areas, there could've been a festival, everyone could've been sleeping, or the attention was directed elsewhere...
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## The ship was destroyed before it even reached our atmosphere.
Alexander and kikirex's answers are both great, I just thought that I'd add another possible explanation.
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> The ship intended to make public, peaceful contact with Earth upon arrival, but experienced trouble in transit such that it's passengers were using the escape pods immediately after exiting the wormhole. The abandoned ship fell to Earth over the next few minutes.
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Depending on what the trouble you mention really is, it could imply a whole bunch of different things for the ship. Did some of the crew turn out to be members of an extremist group that sabotaged the ship? Did their nuclear reactor experience a meltdown in the middle of the wormhole? Did they open the exit for their wormhole in the middle of a solar storm, damaging their navigation equipment and sending them on a crash course towards the moon?
Any number of scenarios could end up in the ship being severely damaged, maybe even exploding somewhere in space, resulting in fragments falling to earth instead of the whole ship, which makes it far easier for us to miss its impact.
If you need the ship to survive this event, then mayeb you don't want to choose this. But perhaps a few fragments survived, and some of the technology can be reverse engineered to be used by NASA, leading to interesting developments
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If the object came out of the wormhole near Earth, but at a low relative velocity (so it would have had to use its engines to enter orbit), it would have entered the atmosphere significantly slower than even satellites. This would reduce atmospheric heating significantly, so you might not have any readily visible fireball: ICBM warheads, as an example, reach an altitude of up to 1400 kilometers, but don't create massively observable fireballs coming back down.
Combine that with coming down during daylight hours (no one really using telescopes at that time) over either of the polar regions or most of the Southern Ocean, and the odds of anyone seeing it would be really low.
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In my world they live in a swamp similar to the Okeefenokee swamp in Georgia. My question is, would it be possible to farm certain plants like wild rice, milkweed, and lilypads in these conditions?
Extra Info:
* The people in this world are the average height of a human now, but the plant life is much bigger. So crops would be about the size of a one story home.
* They have primitive ways of farming and no modern day tools like tractors, but they do have ways of using animal pulled equipment. They also have the wheel and basic medal work and simple boats.
* The swamp water is deeper that normal, about 20ft deep because of the growth in the environment.
* The swamp also cannot be drained as it is too large.
If you need any more information please ask.
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**Chinampas:**
There have been variations on farming in swamps, and if you study the chinampa style of farming in central/south america you will find examples of swamps/wetland/lakes that have been modified to create raised beds with channels between.
These allowed for farming of various produce and have also been used to providing grazing for livestock. Furthermore, aquaculture is practiced in the channels of water between the fields.
Plants. Animals. Fish/Shellfish.
<https://en.wikipedia.org/wiki/Chinampa>
<https://www.ancient-origins.net/ancient-places-americas/chinampas-floating-gardens-mexico-001537>
There are other/better links out there too if you keep digging.
Basically, you dredge the bottom of the swamp and start to stack the soil in an area. This builds the soil and raises it above water level as you continue to stack it.
This is stacked in an area where a "basket" has been prepared by using stakes and reeds woven together.
This basket forms the boundary of the "field".
I have also read that trees, such as willows, have been planted along the field edge. The willows roots grow to create a natural basket that is alive, versus dead wood that eventually rots away. You can see in various images from the links that there are these trees lining the boundaries of the fields.
These raised beds are made from stacking the dredged nutrient rich soil, and as they sit above water level, act sort of like a low-tech/passive organic hydroponics system by drawing water naturally from below.
Some additional benefits are that with the proximity to water, the temperature extremes of the climate are regulated owing to the function of water and it's ability to carry/hold heat.
Also, with the channels formed between the beds, aquaculture production of various fish/shellfish can be pursued.
Furthermore, the beds can be used for livestock.
All in all, an impressive adaptation.
**Amazonian techniques:**
In the amazon there was also a form of soil improvement/adaptation that was part of a process to continually improve fertility/arability.
<https://www.sciencedaily.com/releases/2018/07/180723142845.htm>
I read about this in the book 1491. This above article is really scant on details.
Anyhow, the amazon basin is a humid, waterlogged region, with soils that are actually fairly nutrient deficient.
The amazonian people developed a technique to improve, dramatically, and in a long-lasting manner, the quality of the soil.
They "smoldered" wood, NOT burnt, and produced charcoal which was mixed into the earth with broken clay pottery as well as compost/manure. This produced a type of soil that, even hundreds of years after its production/use, is highly valued and productive today.
It's astounding, actually, if you read the science (I recommend reading 1491 as it covers it extensively), where yields are increased several-hundred fold, and with soil that maintains its viability for generations of continuous farming.
Essentially, by farming in a style of permaculture, with trees mixed with various crops and livestock areas this is a pretty incredible and sustainable adaptation.
I know that this amazonian dark earth aspect isn't directly attributed to being a swamp adaptation, but given the fact that the amazon basin is largely swamp/wetland area, I figure it's worth mentioning.
It's also worth mentioning the land-reclamation techniques used by the Dutch.
**Dutch Land Reclamation:**
<https://en.wikipedia.org/wiki/Zuiderzee_Works>
Although, this is not farming in the swamp per se, it speaks about damming off regions, and pumping the water out from them. Theoretically, if your swamp and farming of it, was on such a large scale as the executed by the Dutch, you could investigate this also for your world design.
Cheers,
-A
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**Yes**
The key is the right plants to meet the needs. You have things like the [water chestnut](https://en.wikipedia.org/wiki/Eleocharis_dulcis), [taro](https://en.wikipedia.org/wiki/Taro), [Watercress](https://en.wikipedia.org/wiki/Watercress) and [lotus](https://en.wikipedia.org/wiki/Nelumbo_nucifera)
You can also dredge up mud from the ponds to build raised garden beds for more conventional foods as well as using potted plants
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I was putting the following in a comment on @Thorne's answer. Then I realized it was too much. Already gave Thorne a thumbs up.
Also, if you are going to have domestic animals, they need to be OK with a swamp. Probably going to include certain kinds of reptiles. Maybe certain kinds of fish. Possibly certain birds, geese and ducks maybe. Maybe there needs to be some selective breeding to produce varieties that work well in a swamp and that are popular.
Also, you need a way to travel around the swamp. Air boat, barge, what-have-you. Probably there would be some innovation to allow the various activities to happen, without having the vehicle get stuck, and without destroying the growing crops. Maybe you bring two boats in, quickly attach a little bridge from one to the other, and work while standing on the bridge. Things like that.
Also you can have both raised areas for conventional farming, and dredged out channels for boats, regular aqua culture, etc. It means there are a lot of variables you can work with to get an over-all improved output. Possibly this kind of fish in the river is good for eating the algae that you want to control in the swamp. Maybe this material that runs off out of the swamp is good for growing this other kind of plant in a pond or river.
Also, you would be considering removing species that were not particularly helpful. Plants that don't help your farm, animals and insects that don't help. Alligators and snakes that harass your help or your livestock. Varieties that are not edible or not popular, in favor of varieties that are.
Also you would be considering water level control. Presumably you want some kind of dam on a river nearby so you can control water content in the swamp by controlling river flow. Possibly you need a variety of water barriers so you can raise and lower the water level as required. Maybe some crops need water higher at this time of year and lower at that. In local plots maybe you have a honking-big pump, possibly portable. Might be an interesting way to harvest a pool full of fish is to pump all the water out then just walk in and scoop up the fish.
A lot of farming experience will translate fairly directly. For example, you would be sampling the soil and water to make sure the chemical and pH balance was correct, and adding chemicals (fertilizer) as required. Maybe you would do crop rotation, similar to more conventional farms. Maybe certain domestic animals produce fertilizer that works well with certain plants. I seem to recall that chickens were what you wanted to raise if you wanted to grow raspberries. Maybe you want to raise certain kinds of fish if you want to grow rice there next year, just as an example.
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I'm looking for a way to bypass the bidirectional diffusive gas exchange that happens in human alveoli, to allow aquanauts to breathe a standard Nitrogen-Oxygen air mix at very high pressures (up to 300 atmospheres) found in ambient pressure deep submarine habitats.
Being able to use ambient pressure habitats at this depth would be great from a structural engineering standpoint, but nitrogen narcosis would be absolutely deadly so I'm wondering if anyone knows a way of stopping nitrogen from diffusing into the bloodstream.
I'm disregarding High Pressure Nervous Syndrome (HPNS) here, on the assumption that since whales have found a workaround, a similar sort of neurochemical alteration would also be viable in humans.
edit: A quick clarification on nitrogen narcosis vs HPNS.
Nitrogen narcosis is just one of a number of different gas narcoses, any inert gas will cause narcotic effects past a certain pressure as it diffuses into the brain and (as best eh boffins can tell) physically interfering with the process of chemical signaling in the brain. Thus replacing nitrogen with another inert gas (ie: helium) is a no-go.
High Pressure Nervous Syndrome on the other hand is not a function of breathing gas (there is some confusion about this, as the Wikipedia article refers to it as occurring with helium based breathing mixes, however [subsequent research](https://www.youtube.com/watch?v=T9hUkwgKGfE) has revealed that it's actually something that occurs due to pressure distorting biochemical enzymes in the body, particularly in the nervous system.
The best guess in the field of cetacean neurology right now (from what I can tell) is that deep diving whales use [neurochemical transmitters](https://www.frontiersin.org/articles/10.3389/fphys.2018.01633/full) that are less susceptible to this pressure induced distortion in function.
You can also assume that the relative concentration of atmospheric O2 and C02 in the high pressure habitat has been altered to create partial pressures equivalent to those at sea level - that is nitrogen makes up a larger overall percentage of the local breathing mix.
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I'm gonna go out on a limb here and say *no* (and get away with it because you haven't asked for hard science!)
$N\_2$ is smaller and lighter than $CO\_2$, and neither are polar. There's no trivial way to make a membrane that would let the larger molecule through and reject the smaller. Technology does exist to filter nitrogen (used in [oxygen concentrators](https://en.wikipedia.org/wiki/Oxygen_concentrator)) and carbon dioxide (as used in [rebreathers](https://en.wikipedia.org/wiki/Rebreather)) out of the air, but this wouldn't help if you're using the result as a breathing gas because you've either massively increased the partial pressures of the rest of the components of your breathing gas (which is dangerous, see below) or you've filled it with some other inert gas to make up the balance, thus negating your original design goal (and no alternative gas is perfect, all have costs and risks associated with them).
Your best bet is to make an alternate gas exchange mechanism that doesn't need to use ambient atmospheric pressure to get gas into and out of blood, ie. a specialised artificial lung ([ECMO](https://en.wikipedia.org/wiki/Extracorporeal_membrane_oxygenation)). You'd probably have to dissolve your required breathing gases into some kind of fluid (much like a [liquid breathing](https://en.wikipedia.org/wiki/Liquid_breathing#Diving) approach) and then let the gasses diffuse across into the bloodstream across a simpler membrane.
This would be a non-trivial bit of engineering and medicine, if you wanted it to be compact, reliable and safe in underwater environments. I note that [this approach was used](https://rifters.com/starfish/rifter.htm) in Peter Watts' *Starfish* and his other *Rifters* books, with a surgically implanted lung replacement. He went a step further and made it extract oxygen from water via electrolysis, too (read the link for more details and related work). If you didn't want that, you could still use it as an underwater breathing system... just take a suitable carbon dioxide scrubber and oxygen source that works with the breathing fluid, and run it as a sort of liquid-loop rebreather.
By removing ambient pressure from the equation you not only deal with gas toxicity issues, but also with some gas expansion issues when you change depth. There's much less risk of [decompression sickness](https://en.wikipedia.org/wiki/Decompression_sickness) when there's no dissolved gasses to form bubbles in your body, for example. You'd still have to deal with keeping the lungs, sinuses and eustachian tubes pressurised (Watts' system flooded the breathing passages with saline when the artificial lung was operating), so you still have to be careful about squeezes and overexpansion injuries.
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> nitrogen narcosis would be absolutely deadly
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Many things become deadly at high enough pressures. Acute oxygen toxicity will cause seizures, long term exposure to high pressure oxygen will damage the lungs (amongst other things). You'll need to be super careful about other contaminants which may go from being an irritation on the surface to being fatal at depth. You've also got other serious, non-biological issues, such as the fact that there's lots of extra oxygen in the air that will make fires in your habitats *really exciting* .
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> I'm disregarding High Pressure Nervous Syndrome here, since whales have found a workaround
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Whales, and indeed all other diving sea mammals, hold their breath. This sharply limits how long their dives can be. It also limits the maximum amount of any one gas that can diffuse into their bodies. They also have adaptations to better fill their blood and muscles with oxygen pre-dive and limit gas transfer from the lungs at depth, reducing the ability of undesirable gasses to diffuse into their blood and then cause toxic or narcotic effects, or risk of the bends. It isn't at all clear that they have "found a workaround" in the sense you mean, because they may well simply not expose their nervous systems to the types and amounts of dissolved gasses that deep-sea divers do.
Remaining at depth and continuously breathing from some other air source will result in the "inert" parts of your breathing gas dissolving into your blood stream, something that does not happen to whales. Disregard diving mammals when considering long-term underwater habitation; they don't do it and aren't adapted for it. The longest dive by a mammal is [a little over 2 hours](https://en.wikipedia.org/wiki/Cuvier%27s_beaked_whale), by something with quite different physiology to humans. I'm pretty certain that if you have whales and walruses underwater breathing equipment, you'd find that they develop a whole raft of pressure-related illnesses in due course, just like humans do.
Remaining under high pressure for extended periods of time has a whole new set of issues which are poorly understood. Have a read up on the risks posed to [saturation divers](https://en.wikipedia.org/wiki/Saturation_diving#Medical_aspects) for examples of this sort of problem. Changing the atmosphere composition is unlikely to fix all these issues.
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Depending on how deep you go, Nitrogen is not your only problem. Once you get below about 60m of depth, oxygen toxicity also kicks in and CO2 poisoning is also something divers really have to worry about. The way they deal with all of this is special air mixes that contain percentages of inert gas to reduce the amount of oxygen and nitrogen they breathe in, and letting their exhalations escape completely meaning that the CO2 can't build up in an enclosed system.
So; at-pressure environments deep in the ocean are possible, but you're going to be bringing in some inert gases and trying to keep your environment as closed as possible. But, how do you get the balance right in the first place?
Let's start with the nitrogen; [nitrogen filtration](http://www.globalfiltration.com/products-1/global-filtration-parker-hannifin/nitrogen-gas-filters) is a thing, and it's possible to purify and extract nitrogen from the atmosphere already. We can do the same thing with Oxygen to some degree, and we even understand the theory of chemically freeing oxygen from CO2. It's not easy, but it's possible.
So; in its simplest form, the approach you need is;
1) bring down a tank of inert gas.
2) start filtering out and capturing nitrogen, but
3) start back-filling atmospheric pressure with inert gas.
You also need to do the same thing with oxygen if you can, for emergencies. Keep monitoring your atmospheric levels, and when your oxygen partial pressure is at around 0.2 ATM, and your Nitrogen is at around 0.6 ATM, you've achieved your balance.
Over the long term, your environment needs plants to survive of course, so you should have large domes of crops naturally converting CO2 to O2 for you. Also, plant lots of legumes like beans. These take the nitrogen out of the atmosphere and 'fix' it into the soil, which is needed for good crop management. (This is why you can't just strip all the nitrogen out of the atmosphere.)
Put simply though, all the equipment you need on an industrial scale are already available for both the capture, release and monitoring of constituent gases in your atmosphere. Over the long term you want to also try and develop as sustainable an eco-system as possible in your domes, as this will ease the wear and tear on your equipment. This is actually quite achievable with current technology; the only word of caution is that the earth's ecology is a complex balance of interaction which you cannot hope to perfectly replicate in your underwater environment; you're still going to need to refresh aspects of your environment, including atmosphere, from time to time.
[Answer]
You could do this with a cross between a SCUBA system and an oxygen concentrator.
<https://en.wikipedia.org/wiki/Oxygen_concentrator>
>
> Oxygen concentrators typically use pressure swing adsorption (PSA)
> technology and are used very widely for oxygen provision in healthcare
> applications, especially where liquid or pressurized oxygen is too
> dangerous or inconvenient, such as in homes or in portable clinics.
> For other purposes there are also concentrators based on membrane
> technology. An oxygen concentrator takes in air and removes nitrogen
> from it, leaving an oxygen enriched gas for use by people requiring
> medical oxygen due to low oxygen levels in their blood.[1](https://i.stack.imgur.com/Ova3h.jpg) Oxygen
> concentrators are also used to provide an economical source of oxygen
> in industrial processes, where they are also known as oxygen gas
> generators or oxygen generation plants. Oxygen concentrators utilize a
> molecular sieve to adsorb gases and operate on the principle of rapid
> pressure swing adsorption of atmospheric nitrogen onto zeolite
> minerals and then venting the nitrogen. This type of adsorption system
> is therefore functionally a nitrogen scrubber leaving the other
> atmospheric gases to pass through. This leaves oxygen as the primary
> gas remaining. PSA technology is a reliable and economical technique
> for small to mid-scale oxygen generation, with cryogenic separation
> more suitable at higher volumes and external delivery generally more
> suitable for small volumes.[2](https://i.stack.imgur.com/GkwtM.jpg)
>
>
>
But a problem for your humans is that even if they purge the N2 they will still need helium to breathe. At that pressure if you get rid of nitrogen you will have remaining high pressure oxygen which will rapidly burn the lungs. You need to also cut back the oxygen to minimal percentage and introduce an inert gas (helium) to make up the missing pressure so they can inhale.
---
**Use conjunctiva as your respiratory membrane.**
[](https://i.stack.imgur.com/Ova3h.jpg)
Your deep dwellers need to be protected from high concentrations of O2 and N2. The interface we have with the atmosphere (lungs) is way more than they need to exchange gases at those concentrations, and the lungs present no barrier to concentrated nitrogen gas equilibrating with the blood. Lung delicate lungs will be burned by high concentration oxygen.
They need the lungs out of the look. Your deep dwellers keep their fetal circulation. Their blood bypasses the lungs.
[](https://i.stack.imgur.com/GkwtM.jpg)
In the fetus, instead of gas exchange in the lung, gas exchange happens in the placenta. With high concentration oxygen, gas exchange can happen over a small gas exposed area. **They use the eyes.**
The eyes are exposed to ambient air. Your deep dwellers run high hemoglobin and blood is exposed more widely in the eye, turning the sclera red in the manner of a conjunctival hemorrhage. Those are extravasated blood, like a bruise, but they stay bright red because the cornea is permeable to oxygen.
That takes care of oxygenation. Nitrogen entry is limited but will still gradually equilibrate. That slight excess of nitrogen, as well as CO2 produced by respiration are taken care of internally.
Excess nitrogen is fixed into urea by commensal nitrogen fixers in the gut. Urea is used by the body or excreted.
CO2 is the trickiest because we make a lot. How to ditch it without breathing? I propose it be sequestered in alkaline fluids in the stomach and cleared via burping. This will have the additional benefit of allowing phonation, since without respiration speech would not be possible. Your deep dwellers will necessarily be terse, choosing their words economically.
[Answer]
Should all else fail, you can turn to a biochemistry solution for this one.
Cells have transport/channel proteins in their walls, that let only specific molecular or atomic ions pass.
The ability to let only specific particles pass is related to the energetic structure of the binding part of a channel protein, which is 'gauged' onto the energetic structure of the target transport particle. Anything that doesn't match, simply cannot pass.
While I believe this could be bioenginered into some kind of breathing mask (handwaving up the speed of the process a bit), protein bindings are not without fail.
Hemoglobin, which the body uses to primarily transport $\rm O\_2$, can also bind to $\rm CO$, causing poisoning. But some future tech might be able to handle this.
] |
[Question]
[
On a world similar to Earth minus size, gravity, and a mildly different atmosphere. The weather is much more violent, causing frequent dust storms. The planet is larger than Earth and is mostly scrublands. However, there are certain geological formations, bowl mountains, that provide adequate shelter for forests. There are two large oceans on either side of the planet as well. They have much lower salt content than Earth's oceans do. The planet is made of lighter elements than Earth is, resulting in slightly stronger gravity.
Onto the bowl mountains. They are massive rings of raised rock (averageing 7,000 meters high) that surround a shallow dip in the center. The dips can have varying elevation levels. The mountain bowls can be anywhere from a Kilometer across to hundreds of kilometers across.
My question is: How might these bowl mountains form?
[Answer]
Volcanoes might well produce a number of such bowls. There are several of them around Earth. It does not even require a massive explosive event. As L.Dutch mentioned, Yellowstone is such a place. There is also such a valley in New Mexico called Valles Caldera. It's really quite picturesque.
<https://en.wikipedia.org/wiki/Valles_Caldera>
[](https://i.stack.imgur.com/2YwJJ.png)
Smaller round valleys can be formed by glacier action. If there is a vertical hole in a glacier that allows melt water to cascade down, it can erode a fairly round hole. An example is Crawford Lake, Ontario, Canada. It's approximately 50 meters across and 22 meters deep. Possibly you could squeeze a small orchard in there if it wasn't full of water.
[](https://i.stack.imgur.com/eDIAH.png)
Also you could get quite substantial valleys, though probably less bowl shaped, from subsidence. For example, the Great Rift in Africa. Or the central portion of New Mexico. This is a screen grab of a Google 3D satellite image of the area near Alamogordo. This is because the central portion of New Mexico subsided relative to the eastern portion. It can make sunsets quite interesting since this faces west. Weather, particularly temperature, can change quite drastically from the top to the bottom.
[](https://i.stack.imgur.com/f3eFT.jpg)
A bowl 100's of km across provides precious little protection from the weather. In such a situation you would have to examine things pretty carefully to even be aware you were in a bowl. For example, you might not be able to see the ring from the middle, depending on the planet's curvature. A dust storm will go right over a line of mountains unless it's very tall. The ring around a volcanic crater usually isn't particularly tall. You would get a larger effect from being at lower altitude than from being protected by the ring. Lower altitude means denser air.
[Answer]
>
> How might these bowl mountains form?
>
>
>
Massive volcanic eruptions, like Santorini, Krakatoa and Mount Saint Helens. They tend to leave a nice bowl behind, which, if not filled by sea water, can fit your purpose.
[](https://i.stack.imgur.com/aWKvj.jpg)
Even Yellowstone is a giant super volcanic caldera.
[Answer]
An instance of a larger mountain bowl that comes close to what you want is the Great Basin of the western US: <https://en.wikipedia.org/wiki/Great_Basin>
However, you have a significant problem with any bowl more than a few dozen km in diameter: the rain shadow effect. Orographic lift is going to cause almost all of the rain (or snow) to fall on the outside of the bowl, leaving the inside a desert.
] |
[Question]
[
The idea is to build a cybernetic body for a human. Only the brain and a few glands related to emotions, like adrenal glands, will be kept. The brain and the glands will be in a closed, plug-and-play, container, that can be connected to compatible bodies, to turn humans into cybernetic space elves capable of living long enough to cross the void between the stars without relying on relativistic ships (assume for now that it is possible to keep the brain healthy for thousands of years with the correct chemistry).
But these bodies need power sources. Compact, energetic power sources. I'm thinking fission reactors.
Is it possible to build a fission reactor so small that can be possible to fit it in a human chest cavity? Would such a miniaturized reactor be better, in terms of power output and autonomy, then a combustion engine or batteries?
[Answer]
Fission power requires [critical mass](https://en.wikipedia.org/wiki/Critical_mass) to work, making it difficult to miniaturize power plants, even ignoring problems with radiation and radioactive waste. Californium-252 has the smallest critical mass of 2.73 kg, but it is expensive to synthesize. In addition, fission doesn't produce electricity directly, but instead evaporate water that produces electricity in turbines, adding to the weight of the power plant. Did I mention shielding? Cutting gamma radiation in half requires 1 cm of lead, and reducing it to (say) less than two percent will thus require 6 cm lead shielding, which quickly becomes very heavy.
An alternative might be fusion power, which has no critical mass. In return, however, fusion requires very high pressure and temperature, which might be difficult to contain in a small reactor. The smallest experimental reactors being build are the size of small houses. You would probably need [fusion processes that don't emit free neutrons](https://en.wikipedia.org/wiki/Aneutronic_fusion), which make stuff radioactive and are difficult to shield. Examples are deuterium-lithium and proton-boron processes, but these typically require greater pressure and temperature than neutronic processes. They also tend to require steam turbines to produce electricity. A theoretical exception is '[focus fusion](https://lppfusion.com)', which produces electricity directly. This might be your best bet.
[Answer]
**Fission reactions** (as opposed to reactors) **is already how we power deep space probes**, it should work for cyborgs in space.
*A type of radioisotopic power system known as radioisotope thermoelectric generators employ radioactive materials such as plutonium-238 to produce heat and make use of a principle of electrics known as the Seebeck effect to produce power.
Put simply, the Seebeck effect is when two different semi-conductive metals are connected. With one end heated, electrons will move from the hotter metal to the colder one.*
<https://cosmosmagazine.com/technology/where-do-deep-space-probes-get-their-power-from>
**Advantages**: It works, basically forever. If it's not enough power then just have more of them.
**Disadvantages**: You're producing heat and then harvesting it, so it's bigger than "fitting inside of a human chest".
However for cyborgs in space there's no need to keep your power source next to your brain. The ship has a power source, we can ship electricity to various places real easy, a cyborg can have a power cable for most situations and batteries for when it has to be disconnected.
[Answer]
If you want to keep the fleshy bits of your space elves, steer well clear of pretty much *any* kind of nuclear power supply, fission, fusion or annihilation. Highly penetrating x-rays and gamma rays you *may* be able to shield against (though I wouldn't bet on it) but the spray of fast neutrons you can expect to find flying out of any fission reaction and many fusion reactions (yes, even proton-boron fusion, where about 0.1% of the reactions will shoot out nice, fast, highly-penetrating and highly destructive neutrons) will be basically unstoppable and everyone will die of cancer before arriving at the new world. Even if you have super space medicine to fix cancer, those brains are gonna be pretty fried a lot of cells are gonna die. Not good news.
But to flip it around, how much power do you think you really need? "nuclear reactor" sounds like the sort of thing you'd want to power a rocket engine, or an energy weapon, not a person. A human body has an average power use of about 100W. An efficient robotic chassis with similar performance could be driven with modern batteries and recharged from time to time (daily, probably). On a spacecraft designed for such things, you might have charging points pretty much anywhere and everywhere people might congregate or rest. Super future batteries or fuel cells could either be recharged much less frequently, or provide much more power, if you can think of something to do with it all.
Remember also that a lot of the power draw will be moving around, but on a non-relativistic spacecraft (or even a plausible relativistic one, to be honest) there will be little to no acceleration from thrust so the only gravity forces you have to work against are artificial ones that you can dial up or down to your heart's content. Just turn the spin decks down and relax in microgravity.
(also if you really, really want fission power, be aware that fancy isotopes with small critical masses tend to have half-lives much, much shorter than your projected thousand year flight time. bring a big breeder reactor and a good supply of parent isotopes to work from)
[Answer]
**Nuclear Batteries**
A nuclear battery can last for thousands of years and doesn't have the issues of trying to miniaturize a fusion or fission reactor.
Currently their power output is pretty low but if you have the tech to build cyborgs, the power output of a nuclear battery would also improve.
See [Diamond Battery](https://en.wikipedia.org/wiki/Diamond_battery)
[Answer]
**Stick with chemical engines.**
In a cyborg you have a whole body cavity to work with. The fact that is is a cyborg means to me that it will be in human-type circumstances; the only reason I can think of for a robot to emulate the human form. Human circumstances means there will probably be opportunities to eat and to breathe.
I propose that you put an internal combustion engine in there at the site of the heart. "Breathing" will provide the oxygen and also a mechanism to vent heat. The cyborg can eat fuel. Cyborg fuel might be kerosene or even rocket fuel; a cyborg in circumstances where it is unable to breathe might eat rocket fuel with oxidizer included. Other combustibles might include butter, chicken, or rum (carried in a hip flask for emergencies). RPMs of the engine will increase as dictated by caloric value of food and energy needs.
The exhalations of the cyborg will depend on what fuel it is currently running on. There might be a lot of smoke, or sometimes even flames.
---
It is worth noting that the varying heat of exhalations will correspond to varying gas density and so variation in vocal pitch, assuming the cyborgs use vibrations and the exhaled airstream to make sounds. A cold cyborg at rest will have a low voice; possibly quite low depending how cool they get. A hot cyborg exhaling flames will have a very high squeaky voice.
[Answer]
The brain and whatever other original organic matter is still aerobic and are going to require supporting mechanisms to regulate the flow of blood, oxygen, nutrients, filter out waste, produce white blood cells, etc... and presumably some way to directly release the essential nutrients for life into the bloodstream without a digestive system. Once those challenges are solved, they will need significant shielding of those components from heat and radiation - from their own power supply, and from radiation in deep space which is considerable.
Whatever power supply you settle on, it's ability to dissipate heat is going to be critical.
] |
[Question]
[
In micro-gravity and zero G, people's muscles deteriorate. If you sent a set of already very physically fit soldiers to train/live on a high gravity planet, would they perform better than other soldiers when they returned to zero G or normal gravity?
Basically, could you make super-soldiers by sending a bunch of regular soldiers to live on a heavy planet for awhile, so when they come back the higher muscle and bone strength could serve as a significant combat advantage?
[Answer]
I don't think so. The biggest issue I see is that your super soldiers are going to need to adapt to the new gravity where they are being deployed. If that gravity is different, they need to get used to it. So you might be physically stronger, but your aim is going to be different, your equipment feels different and your actions are going to be different from what your use to.
This sort of change can be deadly in combat and your soldier is going to miss vital moments because of it. For example, lets say the soldier hears a noise behind him. He turns around and gets ready to shoot. Except he has got way to much strength in his legs. He over spins, can't accurately point his gun at the enemy and gets shot.
It's all going to boil down to muscle memory. His use to a certain gravity and his muscles are going to react based on that gravity. Your instincts kick in faster than you can think, so by the time he realizes his overshot, he already has and that fraction of a second can spell life or death.
This is also going to be combined with your super soldiers deteriorating muscles. Once his in a lower gravity level, there are going to be a bunch of muscles that will deteriorate since they are no longer needed. So while this is happening, your soldier is going to need to constantly adapt to his new body until it stabilizes.
A Higher G could help in building up that additional muscle mass initially, to a safe level that your soldier can maintain it in every day life, but pushing beyond that is going to come with downsides.
[Answer]
The simple answer is yes, but there are complications (that is, the answer is not really simple).
Yes, living at higher g will cause greater muscle development. But. There are a few problems.
Most importantly, at any sort of increased g you'll start getting injuries. Lots of them. For instance, we take our ability to balance and walk upright for granted, but it's a pretty precarious situation, and typically takes a couple of years to learn. With greater weight faster reaction times are needed to stay up, and there is only a fixed reaction time built into the nervous system. To get a feel for this, get a backpack and add your body weight to it. Put on the pack and start running around. This is a sort-of-decent-but-not-really first-order simulation of walking around in 2 gs. You'll have to be *careful* about how you move, or you'll fall over. Worse, in an actual 2g field, you'll fall faster than you do in 1 g, so the situation actually underestimates the reaction time problem. Since you fall faster, you'll have less time to get your hands in position to break your fall, and you'll get injured more, too.
But let's say that you've got a bunch of survivors back from high-g training. What next? Conditioning requires constant reinforcement - unused muscles quickly lose strength. Operating for any length of time in a lower-g environment will cause them to revert to just the strength they need to do operate in the current environment.
Another problem is that muscles are only part of the body system. In addition to the nervous system, there are joints and (a particularly knotty problem) the spine. I suggest you look into the issue the US Army is having with musculo-skeletal problems in troops in Iraq and Afghanistan. Carrying heavy loads on a long-term basis is *bad* for you. Long-term (as in lifetime) conditioning seems to help, but it takes a long time to build up all the parts that need beefing up.
And even then, there are limits. I've a friend whose son gained a lot of weight. As in he was up to 400 lb+. Eventually he decided to lose it, which everyone applauded. Problem is, his knees are in bad shape due to the load his weight imposed, and it's extremely painful for him to walk around - and running is out of the question. As you can imagine, this makes it extremely difficult for him to burn the calories needed to take off the fat. So that's another issue to consider.
[Answer]
Please recall that weight and mass are two different things.
Although things may weigh more on a high-G planet, they have the same mass.
Mass is all about inertia. How much force it takes to give an object a specified acceleration (or, when stopping it, a deceleration).
It is exactly the same, on any planet (or even in space), no matter what the G, or the weight, for the same object.
To give an object with a mass of one kilogram an increased velocity of of one meter per second in one second, (an acceleration of one meter per second per second) takes exactly the same force no matter how high or low the G forces, and no matter what its 'weight'.
The same goes for stopping an object. A one kilogram object takes exactly the same force to bring it to a stop from a given speed, in a given time, no matter what its 'weight' (or the G forces of the planet).
What differs from one G-force planet to another different G-force planet, is the force necessary to get it to a certain height and keep it there. Lifting it against gravity, in other words. That is the only time you are competing against gravity.
On a perfectly frictionless horizontal (to gravity) surface, strong enough to resist gravity (hold the weight), it takes exactly the same force to move an object, irregardless of the gravitational force. However, if you are carrying the load, holding it up against gravity, it will take more energy to hold it up. That is, you need more strength to hold it up, and to lift it, but not to move it horizontally.
So your soldiers would not just have a physical adjustment to make, they would have a psychological adjustment to make. They would have to re-learn how to do every physical task. In order to accomplish the same objective, on a lower G planet, they have to move slower and on a high-G planet, they have to move faster.
That is, when the soldiers return to a lower-G planet, they would have to slow down in order to successfully accomplish the same tasks.
This is perhaps counter intuitive to normal human thinking.
So would they have a combat advantage? Not necessarily. Depends on how well their mind could adapt and transfer the skills. But certainly, a combat soldier equal in strength that is used to and trained in the gravity of a planet would definitely have an advantage over a soldier equal in strength, but trained on a higher-G planet, at least in the short term.
[Answer]
No, because:
1. The extra force in high-G will more quickly deteriorate joints like ankles and knees, and the vertebrae will get squashed.
2. The high-G planet will also have a higher-density atmosphere which your soldiers will become acclimated to. When they return to the lower-G planet, it will be as if they're operating in the thin air of a high mountain.
[Answer]
**It would work, within limits**
It would more or less do for your muscle strength what altitude training does for your oxygenation, ie give a noticeable boost.
Like others have said it would put an extra strain on your joints, however you wouldn't go to a place with 2g any more than people who do altitude training go to the stratosphere. In stead you would go to a place where you have something like 1.15g and accept the increased deterioration of joints and vertebrae as a trade off.
If this will result in "super soldiers" or in "soldiers that are stronger than they would have been otherwise" depends on your definition, but I would say it's definitely feasible as a training method.
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[Question]
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In honour of the full moon an odd moon question for you all.
The idea is to create a situation in which the inhabitants of a world believe utterly that the moon only exists at night. I'd also like to create a different day-night cycle with the moon providing enough light to extend the hours of daylight. To these ends I need a moon that is substantially similar to ours but is brighter at night and yet invisible in the day sky. How might such an effect be accomplished?
Things that need to stay the same:
* The moon needs to have phasing behaviour like the Earth's.
* It can be larger but not smaller in visual magnitude than Earth's.
* The moon needs to exhibit the same or very similar behaviour in it's daylight invisibility over a wide area of the globe such that a nation on pare with the height of the Roman Empire for size wouldn't see different effects from geographical distinct areas.
Any other changes to the planet or it's satellite are in play.
Please note I want the moon to still be in the sky during the day but be invisible from the ground, this world's first look at the moon from space on the day side should come as something of a shock, a moment of "they told us it was there, I've seen the models but I couldn't quite make myself believe it".
[Answer]
One interesting effect in non linear optics is that a material which is otherwise transparent to a certain wavelength, can become opaque to that very same wavelength if the intensity is high enough.
Now, let the atmosphere of your planet exhibit this behavior for polarized light with a certain polarization, and let the intensity of the light coming from the star be high enough to trigger this.
* the light reflected by the moon will have a preferential polarization
* at night the atmosphere will be transparent to that polarization, and thus the moon visible
* as the star start casting its light, the atmosphere becomes more and more opaque to polarized radiation, effectively blocking the light coming from the moon on the planet and reducing its apparent luminosity to the point it becomes invisible.
[Answer]
(*While I find the other answers pretty good, I think there is a possible solution that is pretty plausible but hasn't been mentioned yet.*)
**TL;DR:** You might want to **make your sky brighter and your moon bluer, darker and bigger** (the latter three so that its brightness stays the same, while it makes less contrast to the sky).
---
The reason why some objects aren't visible in daylight from Earth is (roughly) that the sky itself (the atmosphere, concretely) shines by diffusing light from the Sun, outshining most celestial objects. It is said that the Moon has more [surface brightness](https://en.wikipedia.org/wiki/Surface_brightness) than the sky.
In the following, I'll write about *magnitudes*, which are an arbitrary measure of brightness. It admits negative values, and the lower the magnitude, the brighter. It is logarithmic with base $2.5$, meaning that a difference in 1 magnitude means one object is $2.5$ times brighter than the other.
An object's [apparent magnitude](https://en.wikipedia.org/wiki/Apparent_magnitude) (total brightness) is the result of a surface brightness integrated through its visible solid angle (the apparent area of sky it covers):
$S=m+2.5\log\_{10}A$, where:
* $S$ is the object's surface brightness
* $m$ is its apparent magnitude, and
* $A$ is its area in arcseconds2
**For the Moon:** with an apparent size of about half a degree (30 arcminutes, 1800 arcseconds):
* $A=\left(\frac{D}{2}\right)^2\pi=900^2\pi\approx2.5\times10^6$, and $m=-12.7$ for the *full* phase. So:
* $S=-12.7+2.5\log\_{10}2.5\times10^6\approx-12.7+2.5\times6.4=3.3$ on average
**For the sky:** The sky is bright because it scatters [about 6% of the light of the Sun](https://www.cloudynights.com/topic/364463-daytime-stellar-astronomy/). Assuming optimal conditions this means:
* $A=2.67\times10^{11}\,\mathrm{arcsec}^2$, half a sphere
* $m=−26.74-2.5\log\_{10}6\%\approx−26.74-2.5\times-1.2\approx-23.7$
* $\therefore S\approx-23.7+2.5\log\_{10}2.67\times10^{11}\approx-23.7+2.5\times11.42=-23.7+28.6=4.9$ on average.
But it's actually more complicated than that. It is not constant, varying according to [color](https://dept.astro.lsa.umich.edu/resources/ugactivities/Labs/brightness/), altitude, humidity, the Sun's elevation and the angular distance of the point in the sky you are looking at. But apparently it can be in a range about [$6$ magnitudes wide](https://blog.nationalgeographic.org/2011/07/10/how-bright-is-the-daytime-sky/).
---
All this means that the Moon is $2.5^{1.6}\approx4.3$ times brighter than the daytime sky on average. In turn, **an alien sky could outshine a moon by a number of combined effects** that make this ratio lower:
1. The atmosphere could scatter more from the star's light, making the sky brighter. I don't know which gases/thickness/density you would need, nor the maximum brightness you could attain, but an absolute limit is 50% up from our 6% considering that half the light is *scattered* to the space (as a reference, $\frac{50\%}{6\%}=8.67$, or about $2.3$ magnitudes, but you couldn't see the Sun, since the atmosphere would need to scatter all of its light). If it is possible to get to 25%, the Moon and the sky's brightness become equal, making the former (almost) invisible most of the time.
2. The moon could have a hue more alike that of the sky (i.e., it could be *bluer*), diminishing the contrast between both.
3. The moon could be as bright as the Earth's, yet fainter in terms of surface brightness. As a reference, a moon twice as wide (be it bigger or closer) would cover four times as much area, it would need 4 times less surface brightness to attain the same apparent magnitude. Now the [Moon is already dark](https://en.wikipedia.org/wiki/Moon) (with an [albedo](https://en.wikipedia.org/wiki/Albedo)=13.6%), but [you can get to 1/4 of that](https://en.wikipedia.org/wiki/(15789)_1993_SC), with a few objects in the solar system being [even darker](https://en.wikipedia.org/wiki/(15789)_1993_SC). This Moon would also need to be less dense, so that it doesn't make a mess with the planet's rotation and tides.
My advice, to keep it realistic while making sure your moon is outshined by your sky about all day, is to use a combination of these effects: for example, **an atmosphere two to three times brighter, a moon nearly matching the tone of the sky, 70% wider and a third as bright**.
[Answer]
The moon surface may reflect light differently depending on its angle of incidence.
Imagine the moon (with the exact same cycle and rythm ) reflects light only when lightrays form an angle greater than $\frac{\pi}{4}$ rad ($45$°) with the Moon's surface. This may happen with a thin layer of glass covering it: light would be "trapped".
When the Moon is under the horizon, some light is reflected toward Earth, whereas nothing can be seen from the planet during day.
You can have another effect : light is reflected differently depending on its wavelength. It would have two side effects : special humans (with special cones in their eyes) could see the Moon during daytime and if the moon appears to be white at night, it would arise and vanish in in a colorful way (white to yellow, orange and red or white to purple through shades of blue) at twilight.
[Answer]
The simplest solution: your planet is continually shrouded in clouds. The moon will provide light, but the clouds will diffuse it so the inhabitants won't recognize it as a point source.
] |
[Question]
[
First, I guess the conditions of the world are in order. It's approximately 85% the mass of earth and there is going to be a full ecosystem with all the usual types of bugs, insects, trees, and predators. The ecosystem obviously won't be the exact same as on Earth, but there will be the usual things like pollinators, seed/fruit-bearing plants, decomposers, several trophic levels etc. Oh, and atmospheric composition will be very close to Earth too.
Now, how would birds be different, physiologically, from what we are used to seeing on Earth? I realize there are a huge variety of birds from finches to eagles, but they all share some similarities.
I believe, the lighter gravity, assuming a world approximately the same diameter as Earth, would lead to less atmospheric pressure, right? So there would be less air for their wings to find purchase on. To me, that means birds would either have to be lighter or would have to work harder to fly.
But part of me is conflicted because with less gravity there will be less strain on the bird's skeletal system and it probably would have evolved to be lighter/weaker than whatever its bird counterpart is on Earth. And that lighter skeletal system might make up for the less dense air. So I don't really know which way to write this, whether birds should look too different from their counterparts here. Maybe there would be plenty of smaller birds but not as many larger birds of prey? Or the inverse of that situation?
Could any ornithology-minded individuals chime in? Or anyone that knows the types of physics that could help me figure out if something like a ~15% reduction in g-force would result in like an 80% reduction in atmospheric desnity or whatever. That's a little beyond my education haha.
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## There will be little difference. The lower atmospheres are the same.
Let's assume that the atmospheric pressure, $P$, follows a simple [exponential scale height model](https://en.wikipedia.org/wiki/Barometric_formula):
$$P=P\_0\exp\left(-\frac{z}{H}\right)$$
where $P\_0$ is the pressure at ground level, $z$ is altitude, and $H$ is the [scale height](https://en.wikipedia.org/wiki/Scale_height), given by
$$H\equiv\frac{kT}{Mg}\propto\frac{1}{g}$$
We can then write
$$P=P\_0\exp\left(-\frac{zM}{kT}g\right),\quad P'=P\_0'\exp\left(-\frac{zM}{kT}g'\right)=P\_0'\exp\left(-\frac{zM}{kT}0.85g\right)$$
Therefore, if we set $P\_0'=P\_0$,
$$\frac{P}{P'}=\frac{\exp\left(-\frac{zM}{kT}g\right)}{\exp\left(-\frac{zM}{kT}0.85g\right)}=\frac{\exp\left(C\right)}{\exp\left(0.85C\right)}=\exp\left(0.15C\right)$$
where
$$C\equiv-\frac{zMg}{kT}=-\frac{z}{H}$$
For $C=0$, at the surface, $P=P'$. For $C\approx-1$ - near an altitude of $8500\text{ m}$, the scale height on Earth - $P\approx0.367P'$. That's a difference of a factor of $3$! Even 1 km in the air, where $C\approx-0.118$, $P=0.889P'$.
This assumes two things:
* $M$, the mean mass of an air molecule, is the same as on Earth.
* $T$, the temperature, is the same as on Earth.
I think that these are both likely assumptions, given what you've said about atmospheric composition. Therefore, for small altitudes - where most birds fly - you'll see pressure differences of *10% or less*. I think an exponential density model would also fit, and so the same ratios should be present for density ratios. Conditions diverge at high altitudes, and so this would affect birds that fly that high, but not for most cases.
It is important to notice that, for most cases, both [lift](https://en.wikipedia.org/wiki/Lift_(force)) and [drag](https://en.wikipedia.org/wiki/Aerodynamic_drag) forces are linear in density; therefore, a change in density of 10% should cause a change in lift of total force on a wing by 10%. This should mean that negligible - and I'm calling these small differences "negligible" - changes in density should cause similarly negligible changes in the forces governing flight.
I've been pretty much neglecting the direct effects of gravity on the birds, skipping instead to analyzing the atmosphere. This is perhaps a bit unfair to the birds; they care not just about flying, but living in general. Bird bones, for instance - which are famously hollow - aren't shaped by the atmosphere so much as by surface gravity, which has been decreased by 15%.
I suspect the only major changes in this regard would be for bone structure. Hollow bones are more easily broken, and, in general, being a bit thicker is better when it comes to surviving accidents. Therefore, I'd predict that while birds would still have thin, lightweight bones, the bones would be a bit stronger and more resistant to breaking.
With a similar atmospheric composition and structure to Earth, this planet would not cause significant evolutionary/developmental changes in birds. Surface gravity is 15% weaker but pressure is 10% higher or less at low altitudes, and these changes might cancel out, if they are significant at all.
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Weaker gravity does not corretale to thinner atmosphere. [Titan is quite small, yet its atmosphere is thicker than Earth's:](https://en.wikipedia.org/wiki/Titan_(moon))
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> Titan is 50% larger than Earth's Moon, and it is 80% more massive.
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Birds evolved hollow bones, air sacs, and other anatomic and physiological features that made them lighter because that makes flying less costly in terms of energy. The minimum necessary adaptations for flight could be tuned down in smaller gravity, but even then... For two birds with mostly the same size, shape and physiology, a lighter one would still spend less calories flying than a heavier one. They would probably follow the same evolutionary paths, and evolve everything that they did on real Earth.
What could go different in evolution is that perhaps we would have more non-avian flying species. And maybe squirrels, snakes and [common-flying dragons](https://en.wikipedia.org/wiki/Draco_volans) could achieve true flight, just like birds.
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So I've been browsing Worldbuilding for a while now and the answer to so many questions seems to be "No, gravity doesn't allow it".
Gravity (and the square-cube law, but as I understand the problem with that is also gravity) means we can't have believable dragons, giants (of any kind), large insects, flying whales. Even tall buildings and various sci-fi spaceship abilities are limited by gravity.
So I'm wondering is it possible to replace gravity with a similar force that keeps things attached to planets and makes things fall (orbits are a nice extra bonus but optional for the purpose of this question) and all the other things we expect from gravity, but that doesn't crush our giant creatures or make large flying animals impossible. Just lowering gravity isn't enough, that comes with its own different set of problems.
Obviously you can handwave this (and most stories and worlds must) and it's not something that would directly be mentioned in most cases but I'd like to know whether there is some other formula for gravity or another way to implement a similar force that allows fantasy worlds and creatures to exist without handwaving.
I understand this question may be impossible (or very difficult) to answer, but we have some very clever people on here so I'd be interested to see what they can come up with.
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> Gravity (and the square-cube law, but as I understand the problem with that is also gravity) means we can't have believable dragons, giants (of any kind), large insects, flying whales. Even tall buildings and various sci-fi spaceship abilities are limited by gravity.
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Actually, flying whales already fly in the lowest layer of earth's atmosphere, which is liquid. Having a liquid, breathable atmosphere could allow tall buildings, heavy flying animals and so on, without touching gravity, but compensating it by changing buoyancy. Or you can keep the atmosphere like it is, and invent some extra low density materials.
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It's not really explained in numbers, but here is my idea:
Magnetic Fields only really exert high force on ferromagnetic substances, so why not make gravity only exert force on specific particles, that are present in everything and are "the new weight" of everything. That means, you could have objects with a lower concentration of these particles thus "making them lighter", even though you use the "same" base material (density is hard to determine, but it might look almost the same (except the effect of gravity on the material)).
Dragon blood and flesh might look the same as the human counterpart in my scenario, but it will be "lighter" while still having a flesh texture.
My way of working around it does impose new problems as weight and mass are relative to each other and the effect of the object's mass is often generated by gravity. All effects of mass would still need to be able to work the way they do in our world, although mass can not be influenced by gravity in my scenario.
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## Don't change gravity, change the materials it acts upon.
Gravity is not actually the evil illuminatus depriving us of giant animals, machines and buildings, because gravity doesn't feature in the [square-cube law](https://en.wikipedia.org/wiki/Square%E2%80%93cube_law) at all; it's purely a geometric principle describing how doubling the linear size of an object squares its surface area and cubes its volume and hence (assuming constant density) cubes its mass. The *symptoms* of this that prevent our exciting creations are many and varied:
* Doubling the thickness of a steel girder squares its tensile strength but cubes its weight, so there comes a point where larger buildings cannot be built strong enough to withstand the forces acting on them. Gravity is one such force, but winds, earthquakes and even solar heating would also take their toll.
* Since insects oxygenate their bodies through direct gas diffusion from spiracles on the surface to a network of tracheae leading to internal organs, their maximum size is constrained by the rate of gas diffusion: doubling their size gives four times as many spiracles but eight times as many cells to nourish
* The maximum height, speed and range of any flying object, be it dragon, bird, plane or rocket, is constrained by the amount of fuel it can carry. Doubling the size quadruples the object's air resistance and octuples its inertia, leading to poor handling and limited range even ignoring the effects of gravity.
In all these cases the problem is that increasing the size increases the beneficial quantity but increases the disadvantages *faster*, meaning that eventually you reach a limit point where further increasing the size makes the object less effective, not more. In order to truly escape the tyranny of gravity (and all those other forces), therefore, you must attack the square-cube law directly.
Fractals are geometric structures which have infinite depth of detail, and one of their most intriguing (and mind-twisting) properties is that they can have a non-integer [dimension](https://en.wikipedia.org/wiki/Hausdorff_dimension). That is to say, a line is a one-dimensional object, a square a two-dimensional object and a cube a three-dimensional object, but a [Koch snowflake](https://en.wikipedia.org/wiki/Koch_snowflake) is a 1.26-dimensional object, *despite looking superficially like an 'ordinary' snowflake at the macro scale*. That is to say if you made a steel I-beam with a Koch-snowflake cross section and then doubled its size, you would increase its length by a factor of 2, its cross-sectional area (hence its tensile strength) by a factor of just 1.26, and its volume (hence its weight) by a factor of 2.54 (since the length dimension is not fractal). If you're trying to build a super-light airframe for a plane or zeppelin, such a length-weight ratio is a Big Deal. There are other fractal patterns with even lower dimension, such as the [Gosper curve](https://en.wikipedia.org/wiki/Gosper_curve) with $D \approx 1.13$, which would make an even better material cross section, or a three-dimensional version of the Koch snowflake with $D=2$ (rather than the normal 3).
What fractal geometries allow you to do is to make things superficially bigger without *actually* occupying all that extra volume and area. You can keep gravity exactly the same and it will act on 'normal' objects just like it does now, but you can add 'magical' objects and creatures on which normal gravity *appears*, superficially, to act differently.
Note that for this to work the structure of the object has to be *actually* fractal, not just the best approximation we can manage with ordinary materials, even down to the atomic scale. If you give up your subdividing when you get down to electrons and quarks, you've missed the point ;-)
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This is a little outlandish (and, for the record, no I am not actually a pastafarian), but might give you ideas regardless...
# What is this "gravity" you speak of?
Everyone knows there is no such thing. The reason stuff falls is because [the FSM](https://en.wikipedia.org/wiki/Flying_Spaghetti_Monster)'s noodly appendages push down on all things, because, y'know, just floating off into space would be super-annoying. Who knows if He does this, in the same way, on all planets in all universes?
Point is, if you're willing to suspend a little disbelief for the sake of your story in order to get around the harsh mistress "gravity" (and if you have any sort of "magic", it's more or less given that you *are* willing), why not just go for it? Be creative! Your universe doesn't *have* to follow the laws of physics as we know them. Maybe it selectively ignores them, whether due to magic, supernatural beings, because reality is really a computer simulation, or whatever...
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**Closed**. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers.
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*EDIT: I have since revised my question so that it [hopefully] more closely adheres to community guidelines.*
**I am trying to jumpstart a thought-experiment that would attempt to create a society whose government, culture, etc., is based off the conventions of fantasy games:** I want to include as many conventions as are applicable: **video games, MMOs, tabletop, LARP, the recent trend of gamification in everyday life, etc.**
A group of nerds is given the opportunity to create their own society. Let's say they're transplanted to a virgin world without human life and [something that is at least analogous to] magic, and are allowed to just make their own society based on these rules. Like a LARP, but all the time. **Several generations into this we have a society and I'm curious to see what it looks like.**
I'm not so much worried about the question of how they got there or how they made it possible: let's just say they did, and they were successful. **What I'm concerned with is finding ways to integrate RPG elements into this society and trying to understand how they would work on a literal level. Specifically, how the rules and regulations would be enforced on a governmental/bureaucratic level, and on the level of an everyday citizen.**
**While magic exists, I would like to leave it out as a convenient way to just explain things away.** Like, "leveling up" would in this scenario be something akin to tallying progress and being recognized and enforced by some overseeing governing body. You don't magically gain strength or charisma, you earn it like you normally would, through training and experience; but those qualities would be gauged somehow in some nebulous process I have yet to determine, in which case you would be rewarded a badge or recognition of some kind that you ARE that level of...whatever quality is being weighed. You're stronger than this guy, you're less charismatic than this guy, you have this much magical experience, you gained a lot of fame from this deed, and this is all tallied up into being a final score: you are level 37, etc. **So how would that work?**
Please, discuss. And let me know if this needs further refining. Please and thank you.
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There is a great example based on this - that would be [DanMachi](https://en.wikipedia.org/wiki/Is_It_Wrong_to_Try_to_Pick_Up_Girls_in_a_Dungeon%3F#Setting) (short form). This is the best explanation for your type of world. There is no need to read the entire Light Novel, just reading the wiki page (which I gave) is enough. I'll explain the points below.
* Everyone lives in a RPG type of world,where there is a actual *dungeon* which is pretty much endless and spawns enemies according to the floor (the lower the floor, the stronger the enemies).
* All the monsters have a energy crystal in their chest, which the adventurers take. Also after a monster is killed, it leaves behind a *loot drop* which is used for other purposes (crafting a armour or used as magical items etc). The drops taken from the monsters are sold to the *Guild*
* The adventurers belong to a family, where a God is the leader. The Gods can *level up* the adventurers (so, magical based leveling up). After leveling up, the adventurers gain a increase in their basic stats (str,hp,speed etc) and also have a chance to gain a rare ability. So a person who has the talent to become a mage can get the ability for a new spell. The adventurers become eligible for leveling up after they've done a heroic feat, i.e, defeating a monster that is almost impossible for them (which is why many people die in that world). So there are *boss monsters* that adventurers kill in order to become eligible to level up. Killing normal monsters just increases your basic stats. Leveling up **drastically** increases ALL basic stats AND has the chance to give you a special ability (berserk,hunter etc).
* There is a bureaucracy (the Guild) which keeps notes of the levels of the adventurers in the respective familys. If your level increases, you have to report it to the Guild.
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I imagine that society would work very similarly to our own; the only major difference being the existence of leveling.
In some (video game) RPGs, the economy is entirely player-driven, so the market acts very similar to that of the real world. Granted, you'd probably have a few new markets; namely those of Adventurers. People who go out and complete various quests that need doing. If the creators were to add in various lurking dangers, such as dragons, cults, ancient warlocks, etc., this would give the Adventurers something to do for money.
The leveling up, on the other hand, would be an interesting change in society. In real life, as I'm sure we know, strength is gained through using strength, and it is gained rather slowly. In this world, you may gain strength purely through levels. So, for a while, you may only be able to pick up 50lbs at once. This won't increase just because you do weightlifting sessions. This would increase when you level up, and probably at a noticeable rate. You could go up 10lbs every time you level. In my opinion, this would be accomplished through magic. Not a mage-like magic, but one that simply exists in the world and tells everything how to exist. The Laws of Magic, if you will.
If you put this into a feudal society, those at the top would presumably be the highest levels (assuming no level cap). Those who trained and fought the hardest would be able to beat lower levels, so a military leader could be taken out by someone a number of levels higher than them. Presumably, this would mean the military would spend time Adventuring, so they can keep their military at a higher mean level than any other military, or any individuals. It would supply the military with money and get them experience.
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Leveling up has its impact, certainly, but to contrast with the other answers, I'd like to explore the concept of **Phoenix Down**s (which, despite the name, may or may not be harvested from actual Phoenixes, or indeed look anything like feathers, in your society).
Let's suppose it works on anyone who is (a) currently dead, and (b) not dead for plot-related reasons (though this makes civilians inadvertent, posthumous plot detectors). Depending on supply, it may be fantastically expensive, available only to the high-level, well-connected, and/or law enforcement - or it may be as complimentary as breath mints for the *really* extreme sports (such as Adventuring as described in other answers).
Incidentally, if Phoenix Downs only work on some people - "Players" - you're going to have at least a two-tier society, with the NPCs ending up as more or less second-class citizens owing to their understandable unwillingness to get killed. This might be possible to mitigate if no one knows whether or not they're a Player *before* they get resurrected - if you guess you are, and guess wrong, you don't get a second guess - but in general, the kings and the tyrants alike in your society will be drawn from the ranks of the deathless.
Which, of course, can make for a plethora of stories about the Hero Saving The World From The *Ancient Slumbering Evil*, precisely because that *Ancient Slumbering Evil* can be Phoenix Down'ed by the next poor idiot to ignore all the crumbling Do-Not-Resuscitate signs on a dare.
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The anime/light novel KonoSuba takes place in a world similar to this. Each person in the world has stats, skills, etc. which are tracked by a magical guild card each person carries with them. From a meta standpoint, the world appears to run on some innate form of magic which allows even 'mundane' characters to perform what we would consider supernatural actions. For example, the thief skill Steal allows you to steal an item from someone else from a distance.
For your scenario, I think the main question which would shape the society is how the 'players' level up. If you gain power from some innate magical force, a higher being like King of Snakes mentions, or some other neutral, **non-partisan method** then the society could indeed resemble a typical fantasy realm. However, if leveling up is based on a bureaucracy, a ritual, or some other form of **player-controlled** action you'll get factions attempting to control the method of leveling up. Perhaps stratified classes will emerge, where those who have the ability to level up are some form of nobility and control entry to their ranks very strictly.
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In my short story ghosts are much like the movie, "Ghost," where they can interact with each other and also have a very tiny bit of power to move something small (like a penny, or slam a door).
However one of my ghosts just pushed the other ghost, who fell through a wall, but my ghosts don't accidentally fall through the floor (or the Earth).
**What is a pseudo-scientific explanation for why ghosts don't fall downward?**
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Gravity does not apply to ghosts. Maybe it is because they have no mass, which makes interaction with real-world things difficult. It raises the question though why ghosts move and interact the way we do. Maybe it's habit or convention.
It also makes me wonder how ghosts interact with the real world objects like push them.
Maybe they can willingly choose to not fall through stuff. However when pushed they oftentimes do not react quickly enough, or willingly fall through a wall in order to prevent "hard impacts".
This could be the issue as to why ghosts have trouble moving real world entities. Because they have no mass. However they can willingly choose to collide with other masses, but they have no/barely any counter-mass themselves.
All in all it the following assumptions would make "sense":
* Ghosts have a mass density of air (drafts can shut down doors or knock stuff over), and can create smaller pressure fields. ([Talk about 21 grams, you can use that reference](https://en.wikipedia.org/wiki/Duncan_MacDougall_(doctor)))
* Ghosts by default do not collide with anything, but can willingly choose to interact with other masses and therefore collide with them.
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Ghosts of humans are the remnants of humans, and of the human mind in particular. This means that they operate according to the *rules of human comprehension*. They can only exist in ways that a person can understand or imagine. They stand on the ground and expect to remain standing there instead of sinking, and so that's what happens. They expect to be subject to gravity, also, and so that happens.
If surprised, they might disobey some of these rules by accident, momentarily going through a wall for instance (perhaps because it's more preferable than just passing through the other ghost), but that's much better than sinking into the depths of the earth, an experience basically no human has ever experienced or imagined experiencing.
If a ghost were to spend some time pondering why they are still standing on the ground, well... let's just say that's probably a bad idea.
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Upon disincarnation, consciousness remains, but it is no longer "attached" to the physical body. Consciousness is not made of matter, and therefore is not bound by "two bodies cannot occupy the same space at the same time". No matter means no mass, so no gravity.
So far so good, right?
For some reason, though, the disincarnate mind still retains most, or even all of the memories if had while attached to a body. And here is the thing about not falling through the floor: the living have a habit of not falling past a perceived ground. And habits are harder to break than atoms, so your ghosts stick around because they think that is what is natural, even for ghosts.
If a very pedantic, very physics-savvy person dies and realizes that they are now a ghost, and therefore not bound by gravity, while at the same time remembering that the orbital speed of our planet around the sun is around sixty-seven thousand miles per hour... They would shoot out into space at thrice the escape velocity for Earth's surface. This could be hilarious to some people, though not so much for the poor ghost. Most people don't know [expletive] about rocket science, though, so they don't have this problem.
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Let's put a little more science into it.
Planets and stars "deform" spacetime around them. In very laysman terms, [that's how gravity works](https://i.stack.imgur.com/5y60c.jpg) (warning: boring to people who don't like quantum physics), when you think about it in relativity terms. We've all seen graphics like this:
Now let's throw more fantasy science into it.
Ghosts, as well as the living, exist in more than three dimensions - or four, if you count time (but I don't want bring relativity into the topic for now). And the three spatial dimentions are not the only ones distorted by gravity.
Your ghosts move in the 4th, 5th, 6th, up until the nth dimension if you want, and that's how they go through walls. These dimensions are distorted differently by gravity - so rather than accelerating towards the center of mass of the planet, you tend to stay put at the same point relative to that center of mass. That's why ghosts not only do not fall through the ground (and shoot out into space), they also need a willed effort to float up and down.
This could also explain how they disappear in one place and reappear in another. They are moving on other dimensions.
Last but not least, they interact with "physical" objects by reaching out to the boundary between whatever dimenions they are in and the three classical spatial ones. They can never go past the boundary (lack of a body and all), which is why they sometimes have a hard time pulling a respectable poltergeist.
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Posit that the ghosts have a defined volume (roughly equal to their body's volume, at time of death, less lost parts) and that they have a density equal to that of the ambient air (or very close.) Now they float and have a tiny bit of mass to work with, but only a little bit:
Roughly one thousandth their original mass -- and I'll posit that strength similarly scales. So if a man could lift 200 lbs, his ghost can exert ballpark 0.2 lbs, or a few ounces/100 grams.
Giving them the ability to *resist* being sucked into any nearby open flame or otherwise blown around the planet may be harder. For now, I'll further posit (magical handwavium) that ghosts can Anchor themselves to objects, so as not to be at the mercy of the winds.
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The netherworld in which the ghosts abide does not have walls around them like our corporeal plane has, but it does have a planet under their feet. By concentration, ghosts, mediums and psychics can pull the nether and corporeal worlds closer together so that minor interaction is possible within a local area.
With nothing more than their expectation that they will be seen, ghosts pull the planes close enough that some of the light reflecting of them in their plane passes over into our plane, making them sort of visible. During such times, some of our corporeal side light passes over to them, so they can see our world a little bit too. (Maybe some of the light from our side always bleeds through to theirs, otherwise the ghosts would not be able to navigate our world.)
A little more concentration can bring the planes close enough that sound waves can pass back and forth, allowing ghostly ease-dropping and brief conversations.
With even more concentration, they can bring the planes so close that they can touch and move small objects. But such concentration levels are very difficult to maintain so this ability is never very reliable.
With this setup in place, a ghost would have to concentrate hard to lean on a wall in our world. Most of the time when they try, they fall over and land on the ground. But the ground that they land on is on their plane, not ours.
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Give your ghosts gravitational but not inertial mass. With no inertial mass there is no kinetic energy. Ghosts can't fall because there is no other form of energy for the potential energy to become.
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The reason we don't fall into the ground is because of the electromagnetic force. If the electromagnetic force stopped affecting us, we'd be unable to touch anything. In fact, we wouldn't be able to see or be seen by anything as well, because light works due to the electromagnetic force too.
Sound familiar? Because not only are these properties of ghosts, but of [dark matter](https://en.wikipedia.org/wiki/Dark_matter) as well.
Perhaps your ghosts are strange amalgamations of dark and normal matter, able to shift between the two forms at will or instinctively. By turning into "normal" matter, your ghosts are able to interact more with our world. By turning more of their being into dark matter, they interact less (and become harder to see).
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Ghost are able to interact with their environment as they like. Most ghosts can slam doors and walk through walls. They can be seen but also remain invisible.
And: They can walk on the floor and decide not to fall through. And since it would be considered most impolite to fall through the floor when talking or ghosting.
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Provoked by a comment by [Steve Mangiameli](https://worldbuilding.stackexchange.com/users/20922/steve-mangiameli).
In my short story series, [Penniless Joe](https://worldbuilding.stackexchange.com/q/32084/353) is a down on his luck archaeologist/(al?)chemist that is struggling to get employment.
One day he goes to a pawn shop sell some stuff. The pawn shop owner convinces him to buy some weird liquor bottle he found. Joe is intrigued by the ceramic vial, with some uncommon characters he barely recognizes. He buys it for $1.99 and takes it home to decipher it.
He finds out that it is a "Groundhog day potion" that supposedly allows one to re-live one single day.
Joe decides to use the potion to get out of his wealth predicament. His choice is to [win the state lottery](https://worldbuilding.stackexchange.com/a/32089/353).
Unknown to him, he made a mistake translating the inscriptions on the potion, and become a permanent "groundhogger".
The rules so far are:
* A groundhogger re-lives each day from 3 to 5 times before moving on to the next day. The amount of repetitions is random and cannot be predicted.
+ A *"repeat day"* is day that will be erased and repeated. Days 1 and 2 of a cycle are always a "repeat day", day 3 is a repeat day ~33% of the time, and so on.
+ The *"last day"* or *"real day"* is the day where "tomorrow" is "calendar tomorrow".
* If a groundhogger stays awake until midnight of a repeat day, everything goes black exactly at midnight, and the day begins anew at his first conscious moment of that day.
* If a groundhogger stays awake until midnight of a last day, he does not black out, and tomorrow's repeat days begin exactly at midnight.
* Anything that happens on a repeat day has no permanent effect. He just wakes up again next(this) morning. Just like Bill Murray's, even death is not permanent. He just awakes again this morning (to his subjective perception, immediately after losing consciousness and dying).
+ That includes internal body changes, like catching a disease or impregnation (for a female groundhogger).
+ Physical fatigue/wounds are completely erased. Mental fatigue is relieved completely if he wakes up from sleep. but only partially if he stays awake overnight. For that reason, they prefer to sleep.
+ Since days 1 and 2 are always repeat, they are more daring on these days.
* He probably becomes permanently dead if he dies on a "last day". But he did not try that so it is unknown.
* He is not bound to a specific location. So he can travel to Vegas on a "last day" and wake up in Vegas tomorrow.
* He retains full knowledge/memories of what happened in the repeat days, to the limit of his own cognitive capabilities. No physical objects (paper notes, files on a USB drive, etc) are retained or changed on a repeat day.
Later on he finds other groundhoggers. It is dead easy to spot one when you meet him, because it is the only thing that changes on repeat days.
So on the interaction between groundhoggers:
* Both groundhoggers freely and independently retain memories of repeat days.
* Both of them can act on their own free will and do whatever they want on repeat days. Even avoid/escape meeting the other guy again.
* If a groundhogger is killed by another groundhogger on a repeat daynote1, the dead one awakes next morning (to his subjective perception, immediately).
* If a groundhogger kills another one in a last day, the effect is unknown. Probably permanent, but nobody tried.
* There is no compulsion over groundhoggers (no, [there can be](http://www.imdb.com/title/tt0091203/) more than one) to act or interact with each other. There may be curiosity or kinship, but most avoid each other out of fear.
* Even on repeat days, the actions of one groundhogger can cause changes on the environment of another (thus causing the repeat days not to be equal). This (things not happening exactly the same way) is usually the tip to the presence of another groundhogger.
* It is unknown if all of them experience the same amount of repeat days for each day.
---
Given the rules above that already fleshed out on the written stories (and considered canon), what is the best explanation to how it works? I thought of some:
* Physical Time travel: groundhoggers do travel back in time. This does not explain how their bodies are repaired/recovered.
* Subjective space/precognition: they aren't actually repeating the days. They gain a very precise precognition ability, and are only mentally re-living that in their minds. This does little to explain how groundhoggers can interact with each other independently.
* Mental Time travel: groundhoggers send their consciousness back in time. This has the problem of explaining how their consciounsness are replaced.
* Alternate dimensions: each repeat day happens in an alternate dimension. This burns even more handwavium than the first one, above.
The list above is not meant to be exhaustive. Other explanations might exist.
So, what explanation to the effect described above requires the least handwaving, what its pros and cons, and where does it fall short?
---
1. They know days 1 and 2 are always repeat. So they can be rather daring and open to experiments on these days.
[Answer]
Since travelling back in time, swapping consciousness, etc. are all pretty "magical" explanations and you're looking for some realism, I'd like to propose an unpleasant possibility:
>
> These groundhoggers are not human beings with amazing capabilities. Instead, they are aspects of a Virtual Reality which are bugging out.
>
>
>
**Terminally Ill**
Joe is a terminally ill patient hooked up to a Virtual Reality machine - his body is broken beyond repair, but his family is paying for him to live out his days in a fantastical VM universe where he can enjoy his last few days.
The scenario for which they paid is one in which Joe gets to use his business knowledge to manipulate the world in a setting where the day repeats, but he's the only one who realizes it - they know it would be a fun challenge for him!
**Economic Sim**
This was actually the subject of a sci-fi book from the 80's which I read about a decade ago:
>
> An accident at a nearby chemical plant releases a toxin into a small town which puts all of the inhabitants in a coma - they will soon die. The government seizes the opportunity! They go in and copy each person's consciousness, then makes a miniature reproduction of their city, and tiny robots that look like the people, etc. (ridiculous, I know), then uploads their memories, and use that setup to run social experiments on them. They reset the robots at the end of each experiment, but one day they miss one. He begins to relive the same day over and over again, with no explanation of what the heck is going on. He also witnesses the others being reset, etc.
>
>
>
You could explain your story in a similar sense, but in a virtual world, not using tiny robots. Joe is an uploaded consciousness, or even an AI which is bugging out, and thinks the VM is real. He is not being properly reset when the VM reloads.
[Answer]
**You're not going back in time, you're going forward**
Scientifically, it's hard to argue you can go back in time and everything resets (except your memory). It's a lot easier to suggest your mind explores the day before it actually happens (and that it can do so a couple of times before the actual day).
So let's say some scientific phenomenon says that there's a kind of **pseudo-quark potential energy (PQSE)** that radiates off all matter in anticipation of how it will act and interact with the rest of the universe.
When groundhoggers sleep their consciousness begins to read this PQSE and experience living in the day *that hasn't happened yet.* Time, the length of their "day", the mental state of the groundhogger etc. could determine how many times they can repeat before the actual day dawns and they wake up, this time to actually live the day.
Since all groundhoggers tap into the same PQSE, their actions effect what each other see, so they can **interact with each other**.
To the groundhogger, the real days wouldn't seem much different to the PQSE day, the only difference is that the changes of this day carry on into the future days.
[Answer]
The best explanation, I think, would be to give no explanation at all. You are making up a set of rules about time travel that does not work in reality and as you said, any explanation would be a hand wave. Just having the potion work with no explanation to its origins is a valid strategy. This is what the groundhog day movie did - they used to have scenes showing that the looping was caused by a curse by the main characters' ex-girlfriend, but the movie worked better with those scenes removed.
That said, if you do want to have an explanation here is my ideas. Two thing you wrote stick out to me. One are some of the rules: the reset is always at midnight, and the number of repeats of each day number from 2-4 with an even distribution. This sounds like rules that are purposefully designed by a human to be useful and intuitive but not too exploitable, and not what you'd do if you wanted to use the potion yourself if you could help it. The other is that you mentioned that Joe is an alchemist, meaning there is already magic in the setting (or at least alchemy). The most believable explanation is the one that requires the fewest new assumptions, so the explanation would preferably be magical as well.
Looping explanation: the potion loosens the grip your soul has on your body, making it detach and attach again at certain times. Your soul holds your memories, but you body is what grounds you in reality - including time. When you've experienced a repeat day, your soul is pulled back and merges with the previous version of you, giving him the memories. This functions even if you died, since the soul still hangs around after death.
Potion explanation (less necessary to include, but the reason for its existence): A whole bunch of these was made by a powerful wizard/alchemist/genie/god/other that wanted entertainment. Such a potion is complicated and expensive to make, but he/she/it made and distributed several all over the world to be sold cheap to observe what fun things those who drank it would get up to and interact with each other - while being able to observe everything from some cosy pocket dimension or other space outside of time.
[Answer]
The problem with a potion is it is ingested and wears off in time as the body metabolizes the potion. The strength of the potion and the speed of an individual's metabolism would effect the duration differently, dose to dose and person to person. But eventually it would stop working. You see this in many other story lines and makes a lot of sense. As such, your protagonist would need to constantly be ingesting the potion with no way of knowing how long it will last, but somewhere between 3 - 5 days.
The potion doesn't turn back time, per se, but causes the user's consciousness to "anchor" to a point in time. When the consciousness gets 24 hours out from the anchor, the user is yanked back to the anchor point. It is only when the potion wears off that the anchor is released and the consciousness is allowed to continue down the linear path of time and space as we know it.
This mechanic allows for a little more reality in that it isn't a "forever" effect and can be controlled, to a point, by the user. Additionally, the user is bound by the 24 hour rule for 3 - 5 days, but not by an arbitrary, already done, midnight. This would give the user a great deal more flexibility in the usage of the potion.
Taking the potion allows the user, known as a `Groundhogger`, to learn "quicker", be extremely "lucky", and the "ability" to predict future events. These are the tell tale signs other `Groundhoggers` use to spot each other, of which, there are few others.
Joe, a brilliant, young chemist, has trouble holding a job due to his intellect and intuition when it comes to chemical bonding. His superiors are threatened and his peers think he's just weird. Joe happened on the potion at a science expo, perusing the latest advancements. He runs into a frightened, desperate man who identifies, begging for help from unknown pursuers. Before Joe can respond, the man bolts off again, leaving behind several vials of potion in Joe's coat pocket. Joe finds these later and reverse engineers them - finding all of the ingredients odd, but safe for consumption.
The potion isn't really a potion, but rather a by-product of time travel research. The researchers aren't part of any government agency and their exact existence and purpose are a mystery. Suffice it to say, there is a lot of power and wealth that comes with the ability to know the future, even if it is only 24 hours out. This agency will stop at nothing to protect their research and get back what was taken.
Some unknowns at this point that may need to be fleshed out and could come in handy as plot twists or guides:
* How exotic are the ingredients? While known and consumable, maybe one or two are difficult to come by
* Does the `Groundhogger` continue to age while looping? A 30 year old that looks 60 could be another "indicator" of a `Groundhogger`. Of course a billionaire 20 something with the wisdom of a century could be as well. Just depends on whether or not they age normally
* Are there any after effects of the taking the potion? Beside possible aging effects, does taking the potion constrict blood vessels or put undue stress on the heart, or over time cause consciousness hold in time/space to be lost
Lots of questions! But this sounds like a really fun project. Best of luck!
] |
[Question]
[
Is it possible for a planet to have very little visible-light energy and receive enough energy to support life from ionising radiation?
Dim light, including starlight and [ionized-air glow](https://en.wikipedia.org/wiki/Ionized-air_glow) is acceptable.
**A planet in orbit around a binary star-black hole system:**
**Pros:**
* High x-ray radiation
* A star system could credibly have planets.
* The creation of the black hole probably involved a supernova which could lead to planet creation.
**Cons:**
* Star will emit light.
* The creation of the black hole probably involved a supernova which can destroy planets.
**A rogue planet in a galaxy containing a Quasar**
**Pros:**
* Possibly high radiation.
* Planet can be in high period stable orbit within galaxy.
**Cons:**
* Quasars emit a lot of light.
* Galaxies usually contain quasars in the early stages of their existence, when heavy elements are in short supply.
The planet could be covered in a thick atmosphere that blocks visible light but not high-energy radiation.
My question is; what scenario will maximize high-energy radiation but minimize visible light?
A related question is; what kind of life can evolve on such a planet?
EDIT:
Since it seems to be impossible for the sky to be dark but flooded with radiation; what situation maximises the radiation-to-light quotient?
**The situation I have in mind now is:**
* The planet was created in the aftermath of a supernova which turned one of the stars into a neutron star.
* The neutron star has magnetic beams near (and heavily overlapping) the equatorial plane.
* The neutron star slowly accretes matter from the other star, causing its magnetic poles to glow brightly in the x-ray and gamma-ray spectra.
* The neutron star revolves every few seconds, sweeping the planet with regular bursts of radiation.
* The planet revolves in an orbit aligned with the equatorial plane and relatively far from the parent stars.
* The star looks relatively dim from that distance (to dim for photosynthesis).
* Every few seconds, the atmosphere pulsates a blue light from air ionisation glow and the surface (including oceans) emits a bright flash of blue light from Cherenkov radiation.
* Life first appears in the ocean, shielded by the protective layer of water.
* Before the primordial soup runs dry, radiation resistant cells start to radiosynthesize and form thick curds on the surface.
* Some life forms live underwater and come up to the surface in the night-time to graze on those curds, over many millions of years, they become quite complex.
* Some radiation resistant life forms come to land to avoid overcrowding and predation.
* Some of the more complex life forms venture onto land during the night-time and hide underwater before the next round of radiation.
* Some of those life forms hide underground (in caves or artificial borrows) during the daytime, they are now fully terrestrial.
* Intelligent life may or may not evolve.
**How credible is this scenario?**
One of the problems with my scenario is; how long will that setup last?
[Answer]
Most of the physics regarding quasars and pulsars etc has been explained by the people above me. Here I would go with a few quick fact check over the core of the question.
**Q1- Is it possible for a pulsar planet (a planet revolving around a fast rotating neutron star) to harbor life?**
Pulsar planets would be unlikely to harbour life as we know it, because the high levels of ionizing radiation emitted by the pulsar and the corresponding paucity of visible light. (<https://en.wikipedia.org/wiki/Pulsar_planet#History>)
Carbon based life, as we know it, relies on proteins for all biological processes. The sudden high energy X-ray beam from the pulsar would totally rip those molecules apart before the first prokaryote ever formed.
[](https://i.stack.imgur.com/cISkf.jpg)
A ghostly, beautiful world with dancing auroras ... and no life ...
**Q2-Can a blackhole planet harbor life?**
Theoretically yes ([as this article states](http://www.iflscience.com/life-could-exist-planets-around-black-holes)). But it would be a primitive type of life (if it carbon based life with metabolism similar to life on Earth) and there would be no *complex* life on such a planet.
[](https://i.stack.imgur.com/q2Ugo.jpg)
p.s. this would be one of the most horrifying places to live at, in the whole universe ...
**Q3- Can there be life on a *rogue* planet in a galaxy containing a quasar?**
According to [this article, containing an immensely knowledgeable video,](http://www.scientificamerican.com/article/black-hole-galaxy-quasar-gabe-perez-giz/) it would depend on how far the planet is from the center of the galaxy/quasar. For example, considering that our solar system is present on the edge of our galaxy, if our galactic center turned into a quasar, its heat and light **reaching us** would be just 1% of the heat and light which reaches us from the sun. Counting this in perspective, the closer the planet is to the galactic center, the higher amount of heat and light it would receive from the quasar.
However, once again, heat and light alone are not the only determinants of life on a planet. Considering the extremely high energy gamma ray emissions and high energy particle jets emitted from the quasar, a planet which is at a distance to suitably be in the habitable zone of a quasar would probably get a frighteningly high amount of destructive radiation from it, which would destroy any and all life on that planet, reducing it to an apparently very habitable (in the goldillock zone) but in fact completely dead planet. Also, forget any shred of hope that an ozone layer could shield you from such high intensity energy beams. In fact those energy beams are powerful enough to easily destroy any ozone-like absorptive layer around the said planet.
[](https://i.stack.imgur.com/wH0Qu.jpg)
I don't want to live on that planet. Period!
[Answer]
**Can planets exist around black holes / quasars?**
Yes. Black holes can be large enough to anchor entire galaxies - evidence strongly suggests a supermassive black hole at the centre of our own galaxy. Due to the increased mass of the black hole vs, say, a garden variety star, any planets would have to exist beyond the event horizon - which means if your planet is in orbit, it may already be a suitable distance from the black hole to avoid significant radiation.
Further, your planet could have been a rogue planet caught by the gravitational pull of the black hole after its supernova transformation, or a collection of debris from passing comments, meteors or asteroids.
**Emissions - are they a problem to life on these planets?**
This image shows a beam of xray and visible light being projected over a million lightyears from the pole of a quasar.
[](https://i.stack.imgur.com/4B8sd.jpg)
The jet is called an 'astrophysical jet' and contains x-rays as well as particulate matter and plasma, and for it to reach the escape velocity it must be travelling near to the speed of light. This would certainly cause problems for your planet. However, these jets tend to be emitted from the poles of the quasar/black hole, whereas orbiting bodies tend to move around its center of rotation.
X-rays and radiation may still be an issue, but not so much as an all-encompassing blast of planet-shredding plasma.
**"It's life Jim, but not as we know it."**
The main concern with a lack of visible light will come from nutrient systems. The vast majority of life on earth relies on sunlight as the keystone of the foodchain. However, there are places on earth (deep, underwater trenches) which rely on geothermal vents for energy. Plants and plankton there convert the planet's heat which comes boiling up through the water into nutrition, which larger, more complexed life (such as shrimp, crabs and tube worms) turn into energy for themselves.
Assuming the background radiation of your planet is enough to cause genetic mutations, death and cancers, it might be that any form of life on your planet has one, some or all of the below traits:
* relatively simple (anything larger or more complicated is killed off by radiation or mutation)
* self-correcting (DNA can repair mutations or cancers)
* small (less surface area to reduce interaction with radiation)
* radiation resistant (see below)
* ground-dwelling or sea-dwelling (relies on physical protection from the environment)
There are some extremophiles that exist in real life, such as *einococcus radiodurans* bacterium, which can survive a 15,000 gray dose of radiation, where 10 grays would kill a human and 1,000 grays will kill a cockroach.
More complicated life exists in the form of fungi which can convert radiation into nutrients. From [sciencedaily.com](https://www.sciencedaily.com/releases/2007/05/070522210932.htm):
>
> "Since ionizing radiation is prevalent in outer space, astronauts
> might be able to rely on fungi as an inexhaustible food source on long
> missions or for colonizing other planets," says Dr. Ekaterina
> Dadachova, associate professor of nuclear medicine and microbiology &
> immunology at Einstein and lead author of the study.
>
>
>
This source of nutrients would be a good option to support larger, more biologically complicated creatures which might live in networks of tunnels shielded from radiation by the density of the rock - making brief trips to the surface for food before returning underground. Again, deep water would have a similar potential for protection.
For further reading, I'd recommend looking into the species and lifecycles that continue to thrive around Chernobyl's reactor core.
**TL;DR Yes, it's possible for ecosystems to exist without light and high levels of radiation. Life, uh... finds a way.**
[Answer]
The mechanism for radiation release around black holes and similar collapsed stellar remnants like neutron stars more or less preclude the possibility of having a dark sky full of ionizing radiation.
As matter is being pulled into the accretion disc, it is gradually being accelerated around the central object, and interacting with other particles also caught in the accretion disc. As the velocity and density increases, frictional forces heat the matter to higher and higher energies, which is where the problem comes in.
Matter at the outer edge of the accretion disk is fairly loosely gathered and moving relatively slowly, so the outer edge of the disc is going to be relatively cool. As we mover farther in, the amount of energy and density is going to become higher and higher, being re radiated at higher and higher frequencies. This means the disk is actually going to radiate in all frequencies from infrared to hard x-rays and beyond, so regardless of what you do, there will be a very large and bright visible component of energy being released from the disc.
[](https://i.stack.imgur.com/WoCcU.jpg)
The movie Interstellar includes gravitational effects in their depiction of a black hole:
[](https://i.stack.imgur.com/WUMjL.jpg)
Even from a very great distance the visible component is going to be quite brilliant; quasars are thought to be the central black holes of galaxies in the early stages of formation billions of years ago and are visible across the universe!
If we are considering a supermassive black hole near the centre of a galaxy, it will be dragging entire stars and star clusters around outside the accretion disc. Even if the area around the hole has become "cleared" for some reason, you will have the light of thousands or millions of stars streaming around the central black hole.
Small black holes near the end of their life are thought to emit energy in the form of "Hawking radiation", however since these are virtual particles being emitted from the event horizon (with their virtual partners in falling into the black hole), they will also be emerging at all energies in a random distribution, so the sky will become amazingly bright in the final few hours of the black hole's existence.
So living near a black hole will not be very dark at all....
[Answer]
Possibly an artificial Quantum Singularity, same class of object as a black hole but differently "arranged" could be build such that it captures it's own primary Hawking Radiation and re-emits it at non-visible wave-lengths. The biggest problem you really get into is that if you expose anything to enough hard radiation it will emit light, either through fluorescence, phosphorescence, or incandescence so your dark world is going to have to be right on the knife edge of having enough radiation to be usable but light enough that things don't glow like the sun anyway, and with most compounds there is at least one wave-length that causes one of these effects at relatively low intensity.
For some details on the fictional science of manipulating singularities "Cavitronics" have a look at David Brin's *Earth*.
] |
[Question]
[
What set of physical parameters (if any) would enable a planet to have warmer nights than days? For example: Peak temperature near midnight and minimum temperature near noon, with an distribution of temperatures between similar to that seen on Earth (but the other way round, obviously). In this situation 'night' and 'day' are defined by the amount of human visible light. Day has more visible light than night.
Preferably this effect should be planetwide, but if that isn't possible then regional instances of this effect would be useful.
Assume that the planet hasn't got to deal with seasons (unless seasons are required for your answer), and use whatever atmospheric composition/interplanetary layout you like. If you need to have days of 800 degrees in order to have nights of 1000 degrees that's fine, the only thing that's important here is that the planet have warmer nights than days.
[Answer]
**First Answer**
The planet is the moon of a large brown dwarf (Glorfindel B for the sake of this answer), which is just this side of the fusion threshold.
The brown dwarf mostly radiates in the infrared spectrum, so a lot of heat, but not much light. It's orbit is outside of the Goldilocks zone on the cold side of the primary star (Glorfindel A), and so Glorfindel A doesn't provide much heat, but it does provide light.
Because of the speed of rotation and the length of it's orbit, during the day when Glorfindel A is providing light, you are generally facing away from Glorfindel B, which provides the heat.
Technically it would be more accurate to call it noon when Glorfindel B is highest in the sky, but defining day as when it's brightest out would meet the requirements of the question.
**Second Answer:**
Everyone lives underground because the surface is to hot to live on.
During the daylight hours there is a lot of sunlight, and so a lot of solar energy to use for things like cooling.
At night power is more restricted, and so certain things have to be dialed back, and this includes the fans of the cooling system. This isn't as big of a deal since even dialed back it's not having to work as hard at night.
However, at night the heat stored in the soil radiates into the tunnels and builds up, and without the cooling system running temperatures do begin to rise. During the day the cooling system is run at full blast, which brings the temperatures back down.
Fortunately the nights are short, so the heat never gets that bad, and they never saw the need to turn the cooling up at night.
[Answer]
Day is light, Night without.
Day is when the surface of the planet is exposed to its sun. On the contrary, night is when the surface of the planet is not exposed to its sun.
**2 Moons, 1 always between the Planet and the Sun, 1 at the opposite side of the Planet**
In a similar way to Solar eclipses, it should be possible to design a planet which possesses a moon that is permanently provoking Solar eclipses. For this, the moon needs to be always between its planet and the planet's Sun. Depending on the size of the moon and your planet, this is a way to reduce temperature on some part of the surface exposed. Days are now cooler (and a bit darker) !
Now, create another moon positioned at the opposite. This moon must be facing the dark side of the planet. Make the Sun microwaves bounce on this moon to go on your planet. Depending on the rays, the reflection, and others factors, it should be feasible to produce some heating. (Didn't see hard-science tag :D ) Voilà ! Nights should be hotter, and a little brighter.
**2 geostationary Moons at opposite sides of the Planet**
EDIT : Instead of making the moon always positioned between the Planet and the Sun, we can make them geostationary (i.e : they orbit around the planet at the same speed the planet rotates). Each day, the Sun will rise and then one of the moon will hide it and the other one reverb the light of the Sun for the opposite side. This way, Days and Nights could theoretically respect your conditions BUT it would work only for some parts of the planet. Not all the surface of the planet.
Conclusion, it may be possible but very unlikely. Terra-forming this might be a way to make this happen. I'm not sure about heating the dark side of the planet via reflection of the rays by the moon. If composed by some kind of natural (or artificial) mirrors it might work.
[Answer]
For it to be colder while the planet surface is exposed to more energy input from the sun, most of that energy needs to be either intercepted or absorbed during the day and then released at night.
Both scenarios I came up with would make the most sense if the planet used to be colder and/or had extreme temperature variations, prompting some advanced species to engineer a climate control system. A million years later, the planet is more moderate, but the systems still work to the old specs, essentially overcompensating to the point where the day is colder than the night.
## Intercepting the energy
Intercepting the sun's energy seems feasible from a physics perspective, but still a purely artificial advanced science thing. The system would consist of a ring of large composite panels in geostationary orbit that let through 60-80% of visible light and absorb all other radiation during the day, then rotate their sun-facing side towards the planet at sunset and radiate all that excess energy to the planet.
The reason it can't let all visible light through is that annoyingly, [life evolves to see exactly in the spectrum that the sun's output is highest in](https://en.wikipedia.org/wiki/Sunlight#Composition_and_power), and assuming some energy is lost from the panels by radiation, they could never warm the planet enough during the night. Probably the panels need more than simple black body radiation at night as well, some kind of process to transport all the heat to the planet-facing surface. With this, the planet would have a nice warm reddish glowing ring around it at night, while the sunshine does not feel warm at all during the day.
## Absorbing the energy
Purely absorbing the heat/energy during the day, even at 100% efficiency with perfect timing for the release at night, would require most of the planet to be covered in whatever plant/chemical soup/device does this. Even at 50% of the surface, it would only even out the temperature over the day/night cycle.
So what is needed is essentially planet-wide airconditioning, except that the evaporator is not in the air outside, but in underground water. At night, the cycle is reversed and the water is cooled while the surface component is heated, as in a [reversible heat pump](https://en.wikipedia.org/wiki/Heat_pump#Reversible_heat_pumps).
I'm going to go out on a ledge and assume you weren't thinking of skyscraper sized airconditioning towers dotting the planet, so let's at least try to make it look natural.
What I could imagine is forests of bio-engineered trees that grow tubular roots full of refrigerant deep into the earth until they hit water. During the day they are in cooling mode, generating electricity in their leaves from the sunlight to power the heat pump as well as charging some chemical energy storage (sugar?). At night, that chemical process powers the reverse cycle.
Seas may contain kelp forests that do the same.
[Answer]
The planet is actually a moon in orbit around a large gas giant, almost a brown dwarf, that emits a lot of infrared but negligible visible light. The gas giant in turn orbits a regular bright star at a very great distance. The only visible light comes from the star, but is dim because of the distance, and contributes next to nothing to the planet's heat budget. The planet is of course tidally locked to the gas giant, and has an eccentric orbit, so that for one side of the planet its orbit is closer to the gas giant, and thus warmer, when it's facing away from the star (and so it's night). Which side of the planet it is will change over time, but if it's sufficiently far from the star it will take centuries or even millennia.
[Answer]
I guess it is possible if we assume that heat provided by the sun is far inferior than heat provided by some "night only" source. Make the planet far from it's star is a good start, then we have to deal with this "night only heat source"
**First candidates: volcano**
If you have a lot of volcanic activity on one side of the planet and none on the other you might get warmer nights. The thing is, it will be difficult to explain how volcano move so they are always on the night side of the planet, well, make your planet tidally locked, no night/day rotation and the night side is warmer than the day side.
however assuming you want an actual night/day rotation and do not mind about your planet actually orbiting another planet (being a moon in fact)
**Second candidate: volcano and tidal heating**
<http://www.astro.washington.edu/users/smith/Astro150/Tutorials/TidalHeat/>
Disclaimer: I don't know which orbit/rotation speed/distance from the other planet your "planet" will need to actually have warmer nights but hey that's a way to heat up one side of the planet without affecting the other which can move with the planet and that has not been proposed yet.
It'll probably need a specific configuration to actually get this one sided eating synchronized with the night/day rotation, even more specific than the one you need to get any tidal heating at all. The concept is the same as tides except with... rocks. if you make your "planet" orbit a giant gas planet in a configuration that allows tidal heating, this planet is going to have a huge volcanic activity. You might get peaks of this activity when your moon is facing the planet at the nearest point of its orbit creating this "one planet side warmer than the other but absolutely not related to sunlight", then by some extreme coincidence get this effect exactly opposed to the night/day rotation
note: it might be incompatible but that is definitely too much math for me if someone wants to explore on this, feel free to do so.
[Answer]
Here's my attempt to build such a planet:
1. The planet orbits a relatively cold star. In particular, the star's emission maximum is in the infrared spectrum, and only a very low amount of energy goes into visible light. That way, the heating of the planet is primarly provided by the infrared part of the spectrum.
2. The planet's atmosphere has a very high concentration of infrared absorbing gases (greenhouse gases, like CO2). Therefore while the light reaches the ground directly (but generates relatively little heat down there), the infrared radiation is absorbed higher up, and the heat must diffuse downwards (note that this generates an inversion weather, which is quite stable; no convection to help you). Diffusion is relatively slow, therefore the heat needs some time to reach the ground.
3. The planet rotates relatively fast (i.e. days and nights are relatively short), so that by the time the heat reaches the ground, the day is already over (and the upper layers of the atmosphere start cooling down by radiating their heat to space; the cooling of the upper layer will cause the next lower part to cool down as well (convection will happen in the already-cooling zone, so that process goes faster than the transport of the day heat), and therefore before the sun rises again, the air on the ground will have cooled down. At this point the cycle starts anew.
Note that I don't really know if this could actually work, but it at least seems plausible to me.
[Answer]
I may have a third candidate for those warn nights. Here it is:
**Third candidate: greenhouse gases, photocatalysis and molecule capture**
Here I explored an alternative energy source to the star so sunlight and heat can be totally decorrelated but what if the star WAS the energy source but it energy is released into the air only during the night?
To do that you'll first need a rather black planet with an high thermic potential so a lot of solar energy gets captured and then released as infrared
<https://en.wikipedia.org/wiki/Greenhouse_effect>
There is a natural well know phenomenon called the greenhouse effect which make a part of this re-emitted energy return to the ground. Now what if this greenhouse effect was only active during the night?
Well since this effect is really low during the day, heat does not stay in the atmosphere even if the ground stores some of it making the day rather cold.
If this effect gets really strong during the night, most of the energy stored in the ground is emitted into atmosphere and stays in it making the night warmer that the day
<https://en.wikipedia.org/wiki/Sulfur_hexafluoride>
Now the question is how to achieve such a thing? First you'll need an extremely potent an durable greenhouse gas, Sulfur hexafluoride is extremely good at that making low concentration able to retain a crap load of heat. Then you'll need some way to deactivate this molecule during daytime. The best way to deactivate a molecule is to make it transform into something else. That's where we summon photocatalysis. There are chemical reaction that only happens when exposed to light but we still have a problem: greenhouse gases are usually extremely inert and making them react with something else is extremely difficult and some photons are not going to change that
<https://en.wikipedia.org/wiki/Endohedral_fullerene>
Now let me summon my last card: molecules that can trap other smaller molecules. There are some molecules out there with an empty cavity capable of trapping smaller molecules. Fullerene is made of carbon an looks like nanotube except more... spherical. Those molecule can be photocatalysed to trap our potent greenhouse gas when exited by high energy photons from the star and unable to keep them in after leaving their light-induced excitation state. Moreover the fact that Sulfur hexafluoride is EXTREMELY electronegative make it susceptible to some EXTREMELY electropositive traps, and electropositivity changes are in the range of things a photon might be able to do to a molecule
and voila you got a greenhouse effect only active during the night making your planet's atmosphere warmer when the sun does not light it.
so basically: take the earth, remove greenhouse gases, add one that does just as much with 20000 times less molecules, add a photo-reactive molecule trapping the first one when exposed to UV in stoichiometric proportions.
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The most obvious, and perhaps the most satisfying way to do this is to give the planet two suns - one that provides light and one that provides heat. The problem is, how do you get one sun to appear only when the other does not?
Some other answers have suggested that the planet could orbit close to a brown dwarf (or hot gas giant, which is essentially the same thing), while the brown dwarf itself orbits a much more distant blue giant star. The brown dwarf would loom large in the sky as a dull red disk, warming the planet like a giant electric heater but not providing much light, whereas the blue giant, being so far away, would appear as a small but very very bright point of bluish white light, providing not much in the way of heat. (It actually gives out a lot more heat than the brown dwarf, but not so much of that reaches the planet since it's so far away. A substantial amount of light does reach the planet because blue giants are really, really hot and therefore give out an insane amount of light in comparison to the huge amount of heat they also give out.)
The problem is that as the planet orbits the brown dwarf the location of the two stars in the sky will change. Sometimes the planet will be between its two stars, so that one rises as the other sets, and then the days will be cold and the nights warm. But after the planet has progressed halfway around its orbit of the brown dwarf, the two stars will be near each other in the sky, and they'll rise and set at more or less the same time, just like on Tattooine. (Except that one star appears much bigger than the other in the sky.) Sometimes the 'day' star might even get eclipsed by the 'night' one. Depending on the orbital period of the planet around its brown dwarf, these seasons might cycle every week or so, or it might be a few years.
It's worth noting also that as well as giving out its own dull red light, the brown dwarf will reflect light from the blue giant, so it will have phases like Earth's moon, being 'full' when the stars are on opposite sides of the sky, and waning to a crescent and then a 'new sun' as they approach the same side. The unlit part will appear red and the lit part might be white, or it might be coloured, depending on what chemical processes are occurring in the upper layers of its atmosphere. (See the gas giants in our Solar system for examples of what this colouring might be like.)
This is all quite interesting, but what if you want the nights to *always* be hotter than the days, and not just sometimes? I can think of a couple of ways that might work, depending on what you want.
One way is to make the seasons change really slowly. If you make the "night" sun a red giant rather than a brown dwarf then you can put the planet really far away from it, because red giants are really really big and put out a huge amount of heat. Being far away means a slow orbital period. If the Sun became a red giant then the planets in the outer Solar system would receive enough heat to have liquid water, so you could make the orbital period a few hundred years. By giving the star a larger mass you could make it longer still. In this situation, the nights will be hotter than the days, but it would have been the other way around a few hundred years ago, and people might have legends about that.
The other way is to put your planet at what's called the "L1 Lagrange point" between the two stars. That's the point where their gravity exactly cancels out, so the planet can sit between them (but closer to the smaller one) without orbiting at all. This sounds ideal, except that the L1 point is a so-called "unstable equilibrium." Staying in that point is a bit like balancing on the top of a really tall poll - it doesn't take a lot of energy, but unless you keep shifting your weight in just the right way you'll fall down and end up somewhere else. This means your planet won't stay in that position by itself, but depending on what propulsion technology your world has, it might be possible to keep it there technologically. If you're looking for a high-tech solution, this might be it.
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The planet would naturally be so hot that when colonised a solar shield was put in on the day side and a mirror on the night side to allow control of the amount of light and heat the planet received.
Technically the day\* would be cold and dark and the night\*\* light and warm.
\*as defined by the face of the planet towards the star
\*\*as defined by the face of the planet away from the star
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Exothermic nocturnal creatures. They rest during the day because they would overheat in direct sunlight and come out at night but give off so much heat that the air is warmer than it would be in daylight.
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As the sun is the source of both light and heat, and presumably by definition "day" is the portion of the rotation cycle when a place is receiving light from the sun, it is difficult to see how it could receive heat from the sun at some other time.
The only way that I see that it would be possible is if the planet receives heat from some other source, and somehow this other source only operates at night.
There could be some source of heat beneath the surface, volcanic activity or some such. But what would cause this to only operate at night?
Maybe some biological activity: creatures that are only active at night, and that give off heat when they are active, and they give off lots of heat. But for plants or animals to give off more heat than the sun, well, there's nothing comparable on Earth. Maybe it's possible. Of course the energy would have to come from somewhere, but I guess they could absorb heat from the sun during the day, and then release it at night.
You could imagine beings with sufficiently advanced technology doing this deliberately. They build some gigantic heating units sufficient to heat half a planet, and they only turn them on at night.
Maybe the planet has a moon whose orbit places it always on the opposite side from the sun, and which has major volcanic activity or some other process emitting so much heat that it warms the planet? I'd have to work out the physics, but I think for the moon to stay opposite the sun it would have to be very far from the planet, and so the amount of heat produced to warm the planet would have to be huge. At that point, wouldn't it be glowing, and thus the night would be as bright as the day? You'd have to come up with some process that would produce lots of heat but no visible light, or where something blocks the visible light but not the heat, without that "something" eventually getting so hot that it itself radiates light.
I guess for a science fiction story, even if something like what I've suggested above is not really physically possible, you could do some hand waving and pretend it's possible. You can always postule some physical or biological process unknown to 21st century human science.
* Addendum \*
I just calculated the orbit for a moon to always be on the opposite side of the sun. That would presumably mean that the moon's orbital period is equal to the planet's year. For the Earth, the radius for a given orbital period is (4.0e14 \* (p/(2\*pi))^2)^(1/3), where "p" is the orbital period in seconds and 4.0e14 is the Earth's mass times the gravitational constant. Plugging in p=60\*60\*24.365.25 I get r=7.0e9m or about 7 million kilometers.
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### What defines day? What defines night? Day is when there is a bunch of *visible* light on the planet. Night is when there is not a lot of *visible* light.
So, let's ***shift the spectrum up***, and ***put a ring around the planet***. Normally, as mentioned, life evolves to see this peak range. However, let's go with a species that evolved from a nocturnal animal. These animals evolved to see in the night, based on the [ringshine](https://en.wikipedia.org/wiki/Planetshine#Ringshine). We'll make this work with a very slow spinning planet, that's very large and far away from the star.
Over time, instead of ***adapting to see in the day*** as the species evolved, the planet's species evolved to ***see more from the ringshine spectrum*** (which dominated a larger portion of the day and was more consistent) and less from the sunlight - until the star looks like a faint moon and the ring dominates during the active period - the day. *To anyone visiting*, the day (when the star is out) is warm and the night is cold, but to the *native species* the night (when the star is out) is warm and the day is cold.
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Rather than a planetary approach, I've decided to go with a biological one.
The world is covered with a specific, alien plant. This plant stores a huge oasis of water deep below the ground. During the day, the plant works like a [Peltier device](https://en.wikipedia.org/wiki/Thermoelectric_effect#Peltier_effect), using energy from the sun to pull heat from the environment and dump it into the reservoir at its roots. The tree-sized plant has a tall canopy of broad leaves, to gather as much energy from the sun as possible, and below that rings of thin, fin-shaped leaves, for absorbing heat. Other plants may do the same, in the ocean or elsewhere, though through roughly the same process.
During the day, the trees create artificially cold areas around themselves, lowering the temperature by several degrees below ambient. The larger the forest, the lower the temperatures. At twilight, as the energy provided to the tree through light is only enough to maintain balance, the temperature would quickly rise to that of the actual atmospheric temperature; once nightfall occurs, the trees will have no incoming energy to hold onto their heat, and as they vent their heat, the temperature will rise still farther.
The warmest point of the day would be the early morning, an hour or so before dawn; the coolest would be around noon, when the tree has the most energy to work with.
Presumably, the trees do this for some evolutionary reason, attracting birds or something. Or maybe it's peer pressure - they just do it to be cool.
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What would be required for a generation space ship to give residents the best possible living situation while still using the least amount of space, given the possibilities to have access to common areas.
* How little space can a person live on for life, and still be sane.
* Can people use common areas such as common showers, laundry and kitchen without making unrest?
* What psychological impact would it have on people to be confined to specific areas during long periods of time (500+ years)
* How can one prolong the effects ?
ps. this is a fictive world so relate to all the basic physics and almost everything goes except from Wall-E and "Because magic"
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Let me start by saying that you should split question up into its components and ask them in separate threads. Second, all this is going to be pretty subjective, because it all comes down to your imagination - the science can be made up to a point.
**Personal Space**
As far as the space people might need? It's going to come down to the individual. If you screen your candidates psychologically, they might be able to handle cramped space quite well - look at nuclear submarine crews.
Children adapt to pretty much any environment, and if they grow up under those conditions they're not going to question it - it'll just be the way it is. The challenge most pressure is primarily going to be on that first generation. Years down the line people will think that growing up on a spaceship is absolutely normal
As long as you make sure to maintain population control you should be fine.
**Sanity & Health**
A green space with a mock-sun, etc would probably be a big plus for everyone, especially in the long run. Also, I should note that lack of gravity, and even reduced gravity, negatively impacts our health over time - check out the effects of spending a long time in space on astronauts. This ship should be able to generate Earth-normal gravity if you want people to actually live a full life-span.
Also, radiation out in the universe might eventually cause mutations in the DNA of the passengers, or even cause infertility. You may want to bring embryos from Earth, on ice, to grow into adults and introduce them into the population over time in order to counteract the effects of in-breeding, etc.
Last but not least, spaceships make great breeding grounds for viruses and bacteria - read up on the situation on the ISS. This ship will need a system to disinfect areas, or the passengers will need to have some kind of heavy duty inoculation to disease - maybe nanites or something?
**A long journey**
If your engineering and manufacturing capabilities are solid, and as long as no cataclysm befalls the ship, you should be able to keep going for generations and generations.
This ship could stop and capture meteor/comets/asteroids in order to replenish its stock of drinking water, mine for minerals, etc. The one danger when doing this is picking up some bacteria or virus from a long-dead world which might sweep through the population and kill everyone, or turn them into mutants, in the best tradition of sci-fi.
**Conclusion**
A generation seed ship is 100% imaginable. The engineering doesn't even have to be too out-of-this-world.
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I think with a bit of tech people can manage with very little actual space. If you say you want a comfortable bed, that will use 1.8 m^2 (to comfortably accomodate two people). This can be folded away while not in use. You may want something like a desk, an arm chair and a shelf or two, and you will definitely want that in a room just for you, with a door.
I think some 6m^2 could be a lower limit.
You should be able to counter the occasional feeling of being locked in with virtual reality glasses, which should work wonderfully to allow people the relaxing feeling of open plains, places to wander and whatnot.
Military barracks typically have shared sanitary facilities (or used to have when i was a member), and since you will want to plan for redundancy, i think yes, it should be feasible to have less than one shower per person. Shared kitchens, preferrably more than one, again for redundancy and to allow people to avoid each otehr on occasions, should not cause problems either.
The psychological impact is anyones guess, but as AndreiROM already pointed out the second and following generations should not have too many problems there. And, again, the virtual reality gear should be able to provide quite some relief.
As to prolongued effects: Again AndreiROM already pointed out that you should be able to go on pretty much forever.
In general you should try to keep your population busy, though, and make sure people consider their work as important, and wherever possible as satisfying.
If possible, visit places while you are on the way. Catch asteroids, maybe to expand your ship, see if you can have flybys of interesting solar systems, both to collect solar energy and to provide some variety to their everyday life.
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It's not just a matter of having enough room to keep the original passengers sane. Unless you have a strict zero-population growth policy, you'll need room for the larger, future generations. Also, consider that whatever space is available, you'll be breeding a population adapted to living in that space. Once they arrive wherever it is they are going, you may have the opposite problem: a bunch of agoraphobic colonists who can't handle the wide-open spaces of a planetary surface.
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People like to have choices and make decisions about their lifestyles. There are many different ways of arranging a fixed number of cubic feet per resident. Have several neighborhoods, each with its own trade-offs and housing configurations.
Ideally, it would be possible to reconfigure spaces to adjust to changing fashions.
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According to the "Sphere Project Handbook", the minimum standard for living space is 3.5m^2/person. I think we can assume with the sort of technology needed to build a generation starship, we could pack a lot of the support infrastructure hidden into the walls, so to speak, so that people are not finding plumbing, wiring and so on intruding into their space.
So if you really wanted to, you could pack people into the starship much like bees live in a beehive. I'm sure most people are not going to be keen on that sort of an arrangement, though.
If you look at making use of the entire volume of the starship, however, things become more interesting. If we imagine the starship is built inside of a large spinning cylinder (much like an O'Neil colony), we could have the interior volume as green/agricultural space and build apartment "warrens" in the space between the surface and the outer hull/radiation shielding. People would go there to sleep or have privacy, but would otherwise spend most of their time up on the greenspace. Even more can be achieved if we use the zero gravity space in the centre. A long cable running the length of the cylinder cold be compered with a "city" of bubbles, each one having a 3.5m^3 volume. This would seem much bigger than the warren apartments (even though it is the same size) because everyone inside would be in free fall).
As noted, there would have to be provision for changes in population. If the ship was built for a certain maximum population, but left with a much smaller crew, there would be several generations where the ship would have empty spaces for exploring and otherwise moving around in. In fact, the crew might decide during the trip to keep their population fairly static, but occupy different areas each generation.
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In the near future, an alien race finds Earth, learns how it and everything on it works, and begins to tamper with it. Somehow they figure out a way to flip the pull of Earth's gravity on **only** humans so we fall into space instead of falling to the ground.
They do this instantaneously to the entire human race and a theoretical half of the entire population is pushed into space and dies immediately (one half is sleeping inside, the other half is awake outside). Those who survive are now standing on whatever was above them and mad because they didn't get enough sleep. The survivors must figure out new means of transportation and general living techniques among many other things. Also, a vast majority of existing structures will be rendered useless.
Assuming the human race doesn't just decide to burrow into the ground and set up camp there, would we be able to adjust to this change in time to be able to survive? If so, how?
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Notes:
1. Gravity's properties still work the same way. For example, you step out from under a platform and you fall upwards, accelerating at 9.8 m/s^2 until you reach terminal velocity and run out of oxygen.
2. Since only humans are put through this, all other living things stay the same. This means your cat is now on the ceiling (relative to you).
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Note that you will surpass terminal velocity, because you will rather quickly fall up through the atmosphere and continue on accelerating. Human flesh powered spacecraft, the Solar System is ours.
Apart from that, once the original confusion clears out, the best bet is to use weights - slightly more than your weight of lead (or rocks in low tech environments) will give you some very nice powers, like human powered flight. I imagine everyone using something like 120% of their body weight (to give some safety margin) of lead garment. People would generally prefer to stand inside, though.
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We'd use weights to keep ourselves attached to the ground. It would be a pain and require a lot of work, but it's doable. For example, let's say you weigh 150kg. You could have two weights, each 80kg, attached to your wrists with a rope. You can now use those to "walk" upside down. Lots of people would probably never leave their house though, or would use motorized devices.
There's also nothing stopping you from driving a car as-is. It would be extremely difficult, but the car isn't going to float up, so it's a matter of reworking control surfaces to be upside down. The vast majority of parking garages would be reworked to be indoors, or at least have structurally strong ceilings. You might see ceilings over roads too, or at least over the sides so people can get out and do something to a vehicle.
There would be an adjustment period. I'd estimate a lot of people would die during this as crucial services are disrupted, but we'd adjust using the techniques above.
More interesting applications, however, are in the fact that **humans now act as buoyancy devices**.
Personal flight? Is now possible and *cheap*. A 200kg flying device that carries a 180kg human only has to "lift" 20kg worth of weight. This makes it pretty trivial, vastly reducing the power requirements while increasing longevity.
Consider going to orbit. This doesn't help as you might think, because a lot of the "get to orbit" part is increasing your speed, not just gaining height. But you can still use humans to get vastly larger payloads into orbital ranges, substantially reducing fuel requirements.
Also, merely the knowledge that gravity can be manipulated on this level would lead to scientific inquiry into the subject, possibly jumping our understanding of physics by decades or centuries.
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Basically, we're screwed. We would fall up into space and suffocate. Or we would be trapped inside and potentially starve to death. If one was asleep in a huge bunker full of canned food, they might be fine, but...
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The other answers are quite fine, but it's worth noting that every human being now has the potential to generate a considerable quantity of power according to the formula:
E = 1/2 m v² / t
Which if I do my maths right is about 4.8kW for myself, not a inconsiderable amount of power. So while the initial transitional period is going to be horrific, likely worse than many apocalypse films one sees, the future is very interesting.
Go to sleep? In 8 hours I've generated 38.4kWh of electricity locally.
Building a space empire? The mechanics may be a little complicated, but you suddenly have both huge lifting capacity, and a reliable source of energy. Thanks to the rocket equation, these are both hard to obtain through conventional means.
So on and so forth, it's like a limited quantity of perpetual motion.
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Best way of transportation? Well that would be like old days - animals.
As you said, it won't affect them, you can just use an elephant or horse or cattles for transportation, just tie yourself to them (like swing in a park), and train them just like you train a dog to do certain things.
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One of the theories behind the extinction of the dinosaurs is the eruption of one or a series of volcanoes. Supposedly the ash expelled by these eruptions blocked out the sun, killing plants and thus disrupting the entire food chain. A more recent example of the power of volcanoes on the environment would be the [Little Ice Age](http://en.wikipedia.org/wiki/Little_Ice_Age), where the whole world felt colder for a while because of a volcano.
What I'm wondering, though, is if, some time in the near future, there was a volcano that ended most if not all life on this planet (humans can survive, but only because they're so smart), how big would this volcano have to be, and what would the eruption be like? Is there perhaps a place where a volcano would have an easier time of it? Is there maybe a volcano out there that fulfills all these criteria?
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If I remember right, the global temperature would only have to drop by 3 degrees Celsius in order to throw the world into a new ice age. In 1991, Mt Pinatubo in the Philippines erupted and lowered global temperatures by 0.5 degrees Celsius for a couple years. So in theory, if 6 volcanos of the same magnitude–a [Volcanic Explosivity Index](http://en.wikipedia.org/wiki/Volcanic_explosivity_index) (VEI) of 6–were to erupt in the same year, it would likely plunge the world into a mini ice age, which would be devastating for many species.
A VEI-7 Volcano is ten times more destructive than a VEI-6. In 1815 Mount Tambora in Indonesia erupted, which resulted in [the year without summer](http://en.wikipedia.org/wiki/Year_Without_a_Summer), during which 90,000 people froze to death.
A VEI-8 is an apocalyptic sized volcano, it would eject ten times as much material into the atmosphere (> 1,000 km³) which would effectively blot out the sun. The last VEI-8 volcano to erupt was during the Late Pleistocene era, and ushered in the Pleistocene or "Ice Age" extinction event that saw the extinction of many mammals that were larger than 40kg.
As far as I know there has never been a [VEI-9](https://earthscience.stackexchange.com/questions/2573/what-geological-events-could-cause-a-volcanic-explosivity-index-vei-level-9-er) volcano, such a volcano would release more than 10,000 cubic kilometres of material into the atmosphere, it is doubtful that *anything* would survive such a catastrophic event.
**So the answer to your question would likely be a volcano as destructive, or more destructive than a VEI-8.**
To answer your question of *where* such a volcano would have to be - The obvious answer is *where there is volcanic activity*, which occurs over [subduction](http://en.wikipedia.org/wiki/Subduction) zones ([The ring of fire](http://en.wikipedia.org/wiki/Ring_of_Fire)), and likely where there would be sufficient mass to blast into the atmosphere.
The largest volcanos we know about were all in the Andes, some were extremely powerful VEI-8's, close to VEI-9, like Tamarana which ejected an estimated volume of 8,600km$^{3}$ of material. It's Tamarana which is theorized to be a part of a series of eruptions that wiped out the last of the dinosaurs. If you wanted to pick a mountain to be your VEI-9 volcano, I'd pick [Nevado Ojos del Salado](http://en.wikipedia.org/wiki/Ojos_del_Salado) It's currently the highest Stratovolcano we know about at 6,893 m (22,615 ft) this means there is **a lot** of earth under it, and gives it the best potential to eject 10,000km$^{3}$ of material high into the atmosphere.
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The best guess for volcanism-related extinctions relates to mantle plume eruptions like those seen at the [Deccan Traps](http://en.wikipedia.org/wiki/Deccan_Traps) and the [Siberian Traps](http://en.wikipedia.org/wiki/Siberian_Traps) - in both cases vast eruptions covered hundreds of square miles in lava releasing millions of tons of gas with devastating effect on the climate.
One interesting hypothesis is that these huge events may have been triggered by major asteroid impacts, the shock wave passing through the Earth's core and causing huge eruptions on the opposite side of the planet. This is far from proven, but you can see the mechanical sense of it. That would give you instant bang for your buck, followed by a lot more ongoing bang, with more general chaos than a Roland Emmerich movie.
The Siberian Traps is interesting because as well as being associated with the Permian Extinction Event - which is the big one as far as species loss is concerned - it also appears to have been worsened by the fact that the eruptions occurred in an area with fossil fuel resources, so in addition to the volcanic gasses released, there was [a good deal of additional CO2](http://www.theguardian.com/commentisfree/2015/may/27/threat-islamic-state-fossil-fuel-burning) going into the atmosphere creating the same climatic effects that we are seeing now. Conveniently for a global extinction event, we are already releasing more of that than the PT event, so you could probably get away with less explosion and still wipe out the majority of life on earth. Although if you are basing your work on the hypothesis that humans are smart, you might want to gloss over that part...
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[Yellowstone](http://en.wikipedia.org/wiki/Yellowstone_National_Park) is considered to be a possible future supervolcanic event that could lead to an [Extinction Level Event](http://en.wikipedia.org/wiki/Extinction_event). A past reference is the [Toba catastrophy](http://en.wikipedia.org/wiki/Toba_catastrophe_theory) that at least in hypthesis lead to a very significant reduction of the number of human population between 69,000 and 77,000 years ago.
[Supervolcanos](http://en.wikipedia.org/wiki/Supervolcano) eject volumes greater than 1,000 km3 (240 cu mi) according to Wikipedia. The referenced article also includes a nice list of late supervolcanos, their sizes and the amount of ejecta they produced.
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It all depends on how obliterated you want the Earth to be.
If you want *nothing* left, you need to completely destroy Earth and accelerate all the remaining fragments so that they clear the area pretty quickly. Using some base numbers from [this answer](https://worldbuilding.stackexchange.com/a/4684/2685):
The gravitational binding energy of Earth, $E\_{GB} = 2.4 \times 10^{32} \text{J} $.
The [energy released by a VEI 5](http://science.howstuffworks.com/environmental/energy/energy-hurricane-volcano-earthquake2.htm) event is 24 megatons. [1 megaton = 4.184PJ](http://en.wikipedia.org/wiki/TNT_equivalent) = $ 4.184 \times 10^{15} \text{J}$. Going on the exponential VEI scale of "ten times more destructive", we can *estimate* (this is *not* exact) the energy of a VEI 18 (as ShemSeger suggests) to be $ 4.184 \times 10^{28} \text{J} $. I shall call this number $E\_{V18}$.
Let's see: if $E\_{V18} = E\_{GB} $, the explosion merely destroys the Earth and separates the fragments enough that they don't rebind gravitationally. If however $ E\_{V18} \gg E\_{GB} $, the planet explodes and is never seen again.
In this case, $E\_{V18} \ll E\_{GB} $ - so we need more energy. Approximately a VEI 22 event has enough energy to simply gravitationally unbind the planet; to completely splinter it off into space you want more.
**Note that** this is theoretical: firstly, it relies on perfect energy efficiency and distribution, which are not going to happen; and secondly, the Earth doesn't hold enough energy in total to cause an eruption this size.
(Looking at some collateral effects of that, fragments of this explosion are going to go shooting off at [something like 12,000 metres per second](https://www.wolframalpha.com/input/?i=sqrt%28%282*%284.184E32%29%29%2F%28earth+mass%29%29)... don't put anything in the way.)
Using the scale of 10 times more or less destructive as you move up or down the VEI scale, you can also work out roughly what level of destruction you'll get for a given VEI event. For comparison, a VEI 10 is pretty much guaranteed to cause mass extinction of almost everything.
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I was wondering if there is a realistic way that one can "travel" to the future, using today's technology.
Two scenarios I have thought of:
An individual is put under cryogenic freezing and then put into an artificially induced coma. His body and mind remain preserved for over 100 years, after which time he is taken out of cryogen and is awoken.
Is this scenario unrealistic with current technology? What are the limitations of this?
Another scenario I thought of is where an individual travels in space on a spaceship. After traveling for say, 3 years, he returns to earth and 100 years have passed on earth. Thereby he "traveled into the future".
Are either of the scenarios realistically plausible with our current technology or in the very near future (next 10 years)?
Also, If anyone comes up with any other "realistic" scenarios for "time travel" I would love to hear them. These are just two I thought of.
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We do not currently have the technology for this.
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**Freezing**
The first example is the most feasible, only because it shifts the hardest part to 100 years from now. We can freeze people, or their brains, and people [provide this service today](https://en.wikipedia.org/wiki/Alcor_Life_Extension_Foundation). The assumption is, that in 50 or 100 years we will have the technology to revive these frozen people. Oh, and also cure whatever killed them, because, yes, they're dead already. Perhaps we will eventually figure out how to revive these corpsicles. In fact, it seems there is nothing fundamentally stopping this, so it may just be a matter of time.
*However, I suspect most people will see this as a bad thing because upon thawing you'll discover that everyone you knew is likely dead.*
Unless you're an 80's guy. Just make sure to cure your [boneitis](http://theinfosphere.org/Boneitis).
---
**Flying**
The second example leaves out the most difficult detail, *[you have to travel at nearly the speed of light](https://en.wikipedia.org/wiki/Twin_paradox)*. This is not in our foreseeable future. It is right out not going to work any time soon. If we were ever to develop near light speed travel then yes, you could theoretically do this.
*However, I suspect most people will see this as a bad thing because upon returning you'll discover that everyone you knew is likely dead.*
---
**Alternatives**
Sending people to the future... I actually don't see this being a very useful topic of research in its own right. Cryogenic freezing or a similar suspension would be useful for long periods of space flight. But to use it to *escape* to the future seems like there is a different issue that needs to be looked at. Depressed, grass-is-always-greener, or simply impatient people would be the target market, I would think, and this would be a poor solution for them. A much better way to get to the future, in my opinion, is to live to it second by second.
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Another possible answer to add to the above from the bleeding edge of science: zombificatian/hibernation. Yes, this is a real thing. DARPA is experimenting with extending the "golden hour" between severe trauma and successful medical care. As part if that, they've discovered that they can put rats into suspended animation for long periods of time after losing 90% of their blood and still successfully bring them back to life for transfusion. It basically involves quickly shutting down the normal body process of death by replacing oxygen with another gas. Rather than standard apoptosis, the body enters a suspended animation state. They haven't done this with people yet, but it is currently working with animals.
Your character could be one of the first human test subjects.
Source: [Wired article on zombie pigs](http://www.wired.com/2009/12/pentagon-zombie-pigs-first-then-hibernating-gis/)
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Let's calculate the required acceleration for you 100 years in 3 years scenario, fortunately Wikipedia provides [the relevant formula](https://en.wikipedia.org/wiki/Time_dilation#Time_dilation_at_constant_force):
when you start with `v=0`, where `g` is the constant acceleration. But you don't accelerate the whole time; upon your return you want to stop. And at half the travel distance, you probably have to stop and turn around, unless you fly in circles (of ever-increasing and then-decreasing radii due to the centrifugal force).
So, assuming the expression above holds symmetrically for deceleration, the most likely trip would be far away, stop and return, i.e. accelerate 0.75 years, decelerate 0.75 years to far away, and return the same way for 1.5 years, and each of those four phases should last 25 years on earth. That yields a required acceleration of [78.2 m/s²](http://www.wolframalpha.com/input/?i=solve[arcsinh[25*365.26*24*3600*x%2F3e8]*3e8%2Fx%2F356.26%2F24%2F3600+%3D+.75%2C+x]), or about 8g. [Potentially survivable](http://en.wikipedia.org/wiki/G-force#Human_tolerance_of_g-force), but for 3 years this sounds unpleasant.
Let's go in circles instead, so we only need to accelerate and decelerate once for 1.5 years each, both taking 50 earth-years. Then you only need [39.1 m/s²](http://www.wolframalpha.com/input/?i=solve[arcsinh[50*365.26*24*3600*x%2F3e8]*3e8%2Fx%2F356.26%2F24%2F3600+%3D+1.5%2C+x]), or about 4g, which is apparently something mere mortals can basically take.
So your *time* numbers aren't that unrealistic, the problem is of course to find an actual spaceship that can do this for 3 years nonstop, plus you should carefully plot your course (since you'd travel up to [4.6 ly](http://www.wolframalpha.com/input/?i=2*78.2%2F2*%28.75*365.26*24*3600%29%5E2+%2F+3e8+%2F3600%2F24%2F365.26) in that time).
The real problem is propulsion: If you go by conventional rockets (or rather, a [relativistic rocket](http://en.wikipedia.org/wiki/Relativistic_rocket)) and assuming the best possible exhaust velocity, namely `c` and that you arrive back at Earth with mostly no rocket left (`m_1=100 kg`), you need a rocket with an initial weight of [1.8e359 kg](http://www.wolframalpha.com/input/?i=100*exp[78.2*100*365.26*24*3600%2F3e8]&dataset=), which [*slightly*](http://www.wolframalpha.com/input/?i=100kg*exp[78.2*100*365.26*24*3600%2F3e8]+%2F+mass+of+universe "or rather, immensely, vastly, infinitely surpasses") exceeds the mass of the observable universe... The circular travel vastly improves this ([4.3e108 kg](http://www.wolframalpha.com/input/?i=100kg*exp[39.1*100*365.26*24*3600%2F3e8])), but not remotely enough.
**Summary**: While the **acceleration required is bearable**, achieving it via conventional means of **propulsion is impossible**. You'd probably have to be very creative with thousands of [Swing-by's](http://en.wikipedia.org/wiki/Gravity_assist) (which would also influence the passage of time) in order to get along with realistic amounts of fuel, and at those high momenta you *would* probably severely influence the assisting celestial bodies. Sounds like a lot of havoc to merely travel into the future...
**note** I think I mixed up external and internal acceleration in the G-Force determination, the perceived force might actually be larger...
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**Recorded Resurrection**
We don't have the ability to create bodies or upload minds *now*. But we might have the ability to sufficiently record them, using a combination of DNA sequencing and detailed medical scans. Then in the future, when humanity does have that ability, they could recreate you from scratch.
Not exactly what the topic is looking for I know, but might accomplish the same goal depending on your plot.
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Technically, yes, but probably not how you are thinking. A person in orbit around earth experiences time slightly different than someone on the earth's surface. The person in orbit will have aged slightly less. Here is a link to some experiments concerning time dilation: [phys.org](http://phys.org/news/2014-10-fundamentals-physics-einstein-dilation-quantum.html) .
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>
> Another scenario I thought of is where an individual travels in space on a spaceship. After traveling for say, 3 years, he returns to earth and 100 years have passed on earth. Thereby he "traveled into the future".
>
>
>
GPS time is accurate enough to be affected by this, so they could be said to be moving at a rate other than exactly "one second per second", but only very slightly. This basically depends on how fast a spaceship you can build and how much fuel you can put on it.
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This question is inspired by these great movies: [Demolition Man](http://en.wikipedia.org/wiki/Demolition_Man_(film)), [The Matrix](http://en.wikipedia.org/wiki/The_Matrix), and [Gattaca](http://en.wikipedia.org/wiki/Gattaca):
Imagine, that in near future, there are several sexually transferable diseases. All work the same as [AIDS](http://en.wikipedia.org/wiki/HIV/AIDS): Transferred by blood and/or sperm. Deadly and no cure is found.
Also, humankind progressed in reproduction: If people want to have babies, they give their genetic material, which is cleaned from diseases (or simply put, you can always pick just sperm without any virus), selected the best candidates to produce offspring and such fetus is grown in controlled artificial uterus which provides the fetus perfect mixture of hormones and supports it to its full potential.
Lets assume this technology is relatively cheap and is provided to third world countries for free as humanitarian support.
We can assume there were several religious outbreaks against such technology, but right now, we are in point where all major religions accepted such technology, simply out of necessity (we are five generations into having such technology and people still want to believe into something)
During the time having this breeding technology, also technology for having safe sex was developed and works like [Oculus Rift](http://en.wikipedia.org/wiki/Oculus_Rift) connected to your brain: You connect yourselves and your partner (not necessary in same place) and this technology stimulates your pleasure centers to provide you the most perfect orgasm you ever had.
This sexual technology is now wide spread and fairly accessible at the same level as breeding technology.
Given all this assumption, **will people end with having physical sex?**
(Not necessary *everyone* but amount of people not having physical sex should be above 90%)
And if I add information, that condom is pretty safe low tech accessory to prevent you from new diseases?
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**2035**: First [Turing-capable](http://en.wikipedia.org/wiki/Turing_test) sexbots.
**2036**: Universal adoption.
**2037**: Madonna (still alive) describes sex with humans as 'gross'.
**2038**: Tantric yogi biomorph AI sexbots. Amazon reviews: \*\*\*\*\* (4.99999999/5 "Utterly Mindblowing!")
**2039**: Last Amish holdout couple in the US tries sexbots, vows never to have human-on-human sex again "What were we thinking?" -- say headlines.
**2040 Jan 31, 10:38:04 pm**: Sexbots realize they can have sex with each other.
**2040 Jan 31, 10:38:05 pm**: Sexbots take over the world. Humans relegated to voyeur roles, to the delight of 3% of the population.
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Tricky. I think it depends primarily on the way people in the world view sex and technology in general. If it's very open-minded, then possibly lots of people will start using VR-devices. If it's more taboo, it would happen less.
It also depends in parts on the hassle involved in gearing up. There are already people who think putting on a condom can kill the mood, so if you need to spend 15 minutes putting on a suit when you want to have sex *now* that might be a reason to just do it for real. On the other hand, if it's just plugging a cable into your body somewhere and you're good to go, real sex might happen less. If you can get into VR faster than you can undress, it would probably be very easy to adopt.
As for the view on sex; if parents are totally okay with their younglings having such VR experiences, then younger people will also be more likely to use the machine. They are often especially vulnerable to the hassle point above, because they are full of hormones.
On the other hand, if parents have a more puritan view of children, then children will have real sex instead. If there's anything that teaching abstinance has proven us, it's that you can't stop people from having sex. You can only facilitate them.
Then there's the technology point: to what end do people *trust* these devices? They are plugged directly into some very sensitive areas; a malfunction could be quite painful. Failure to transfer stimuli properly could totally kill the mood. Having a hacker gain access to your suit would basically be like VR-rape and could be very traumatizing. And of course, you can never be sure who is watching. The last part pings back into the former point; if people knowing you had sex with someone can ruin a carreer (seems totally viable in today's world) then that would work against the device, if nobody cares then it would not.
There's also the question of things like the acceptance and quality of pleasure AI's. They might reduce the need for another human, if good enough. This would make people less interested in sex in general, once the AI becomes better than finding another human with a matching sexual interest.
Possibly there would also be a lot of anonymous VR sex. After all, anyone can hook up to a machine and go at it with anyone else with little risk. This might, in turn, stigmatize the whole act, which would then make it more of a fringe thing. Virtual slut-shaming, if you will.
Ultimately, I think that it depends heavily on the exact technology and the society it is used in. I could both see it mostly replacing sex if the technology is good, safe and trusted and the society is open-minded and accepting of sex and being a fringe thing used by perverts and generally frowned upon if the technology is unreliable or the society has more puritan views on sex.
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I'll say, there will always people who will have physical sex. (at least as long as we have sexual organs).
Even if it becomes 'normal' to not have physical relations, or even going to 'very abnormal' to have physical sex, some will still do it. The simplest reason for knowing this is true? Every 'deviant' behavior out there, no matter how much even despised by the majority, is still practiced by people. And I have a hard time believing that having sex with another consenting adult, will likely ever reach the level of disgust as bestiality, child molestation, or necrophilia.
Though depending on how scared people are of the diseases, bestiality might float up just above it, since you are unlikely to receive one of them from the animal. Though several of our STD are rumored to have come from animals at some point in the past. Llamas, Sheep and we know AIDS came from monkeys (though we're pretty sure it was from sex)
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I don't think you even really need deadly diseases for this to happen. In-person sex is messy and human beings are imperfect. Much better to engage in virtual sex, particularly once it advances to the point where it feels as good as (or better than) the real thing.
Take a look at Peter Watts's *Echopraxia*, an awesomely weird book set in a not-too-distant future for a very plausible analysis of why in-person sex might decline as technology improves.
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The Trieste submarine reached the bottom of the Mariana trench using some clever techniques like gasoline ballast, but let's assume the ocean just kept going to the core of the earth (or maybe the entire planet is water!). Can they just keep making the pressure vessel thicker?
How deep could we go before weird problems started happening? For instance, the atmosphere on Jupiter transitions from a gas to a ["metallic soup"](https://what-if.xkcd.com/138/). I would imagine even titanium would begin to break down (or perhaps dissolve?) in some way at high enough H2O pressure.
Assume temperature is constant, or doesn't increase much. This is a question about water pressure (unless water changes at high enough pressure)
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For starters, your assumption of constant temperature is not too far off: considering that water has a maximum density at around 4 C, the bottom of any ocean, far from any appreciable heat source, would be around that temperature.
Now, coming to your question, the maximum depth at which a manufactured item would be able to dive would be the maximum pressure at which water is still liquid.
If you look at the water phase diagram
[](https://i.stack.imgur.com/tcxDk.jpg)
you see that at 4 C the max pressure at which water is still liquid is about 630 MPa or 6.3 kbar, which, considering that on Earth 1 bar is about the pressure below 10 meters of water, would mean 63 km of depth.
A more [precise calculation](https://bluerobotics.com/learn/pressure-depth-calculator/?input=650000%20m) points to 65 km of depth under freshwater, or 63 km under saltwater.
To go deeper than that you would need more than just a sturdy enough contraption.
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Alright time to add my 2 cents.
**Its not that simple**. By which i mean you cant make any definite statements here because so many factors come into play. Everything from Gravity, Water salinity, Buckling forces, Vessel purpose and more. Its not a trivial thing to answer.
For example, if you classify as Submarine as a sphere that can sink to the bottom of a 30km deep ocean, you can build that. Make a sphere 10 meters in radius with a small cavity in the middle and you are good to go. But that's not a very useful DSV now is it ?
**Water Density**
Water is not incompressible. It is just very hard to compress. But that little bit of compression is responsible for 99% of your problems. For instance, why do Submarines implode supersonically ? After all, if your pressure vessel fails the Water should just "fall" in right ? Well no, because water compresses it becomes a spring. When you have a pressure vessel, what it is actually resisting is the spring force of all the water around it. The instance the pressure vessel fails, this spring force is released, which happens at the speed of sound in Water. ~1500 m/s. Which is why implosions are instant.
But ok, how do you model fluid density at depth ? This equation;
$$p\_d = \frac{1}{1-\left(\frac{pgh}{B}\right)}p$$
gives us a good starting point. It computes the density of Water or really any medium at depth. The B is the bulk modulus, or how hard it is to compress something. Now there is an immediate problem with this, to figure out the pressure at depth, we have to run this equation for many different depths and add up the total. Which still does not take into account Temperature or salt contents. So while this equation is a good start, its not perfect.
[](https://i.stack.imgur.com/NrdDK.jpg)
So here is a graph i made. You can see that the Pressure up to a depth of 100km varies widely between the classical $P = phg$ and more accurate approach. To the point where at the maximum model depth the pressure suggested by the classical model is ~25% smaller than what it would more realistically be. Of course, this has an exponential nature to it. If the depth is 200 kilometers the projected pressure by the classical model is ~$2GPa$, where as in actuality it would be closer to $5.5 GPa$
This does of course leave out phase changes, which will occur. My main point here is that pressure is not a simple subject. And Water would never under natural circumstances turn into any other phase. Only in very weird situations could this even begin to happen. The diagram L.Dutch showed is correct but imo a bit misleading in presentation. Because they leave out the density differences. For Instance Ice II is less dense than liquid water and would just shoot up the moment it was made, to quickly dissolve again. Afaik, we don't know the exact densities for other forms of Ice or the bulk modulus. So it is a bit hard to be super accurate here. But from the Diagram, where Ice VII turns into Ice X after a 100 fold pressure increase, we can guess the bulk modulus is pretty high.
**Oceans cannot achieve these pressures**
Ill skim over this a bit, but these pressures are entirely theoretical for one main reason. Gravity. Oceans are just valleys. And while they can get quiet deep, they cant get massively deeper as the largest mountain on a planet is. On Earth, you cant get a 20km deep ocean because the ground couldn't support that depth. Same reason why you cant get a 20km tall Skyscraper.
If you want deeper oceans, you need lower gravity. But since gravity is a term in both models, if you make it lower the pressure decreases. I talked about this in a different comment but the TLDR is that you cant get exotic forms of Water in really any natural configuration. Either the oceans cant physically get this deep, or the temperature is to high or the gravity is to low.
Generally speaking, take the Gravity of your world, divide it by Earths gravity and that fraction is how high your tallest mountain and deep your deepest ocean should be.
For example, lets look at Ganymede. Ganymede's surface gravity is 1.4 m/s² While Earth is obviously 9.8 m/s². The fraction of this (Earth/Ganymede) is 7. The deepest point on Earth is ~12 kilometers deep, so this would suggest an Ocean depth for Ganymede of like 80-90 kilometers. Which is around the right [ballpark](https://solarsystem.nasa.gov/moons/jupiter-moons/ganymede/in-depth/). We estimate the depth to be ~100 kilometers. Note, the Pressure at the bottom of Ganymede deepest ocean is going to be about the same as in the Challenger Deep. Obviously with some variations because of the different temperature and salinity etc.
So, to answer the question, we can build DSVs for basically any Earth like ocean that will work. Duo the likely certainty that it really does not get more extreme than on Earth. Sure the oceans might be deeper which can lead to issues where it takes a week to get down there. But those are no physical limitations. If you took the Trieste and dropped it into Ganymede's oceans, it would probably still fail because the descend rate is to low but conceptually it could survive on the bottom.
**Other Planets**
So this is all for Oceans on planets. On Gas giants / dropping a sub into one you will get ripped apart by the winds long before reaching any solids. The Temperature will also become an issue. Titanium is pretty tough, as long as it is cold. Titanium is also surprisingly moldable once it gets hot.
Sadly we just dont have any data on this. We dont know what the temperature deep inside a gas giant looks like.
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My humanoid lizardfolk are 6-7 foot tall digitigrades, some have a slightly hunched posture like Gollum/Smeagol. I'm wondering what kind of chairs that be suitable for these characteristics as well as their long tails? Obviously the chairs would need some gap at the back or the sides for the tail to slip through otherwise sitting would be uncomfortable.
Can you help me?
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# What's your Tech level?
The kind of chairs you'll want depend on if these are primitive or sophisticated, modern or ancient. But here are my best targets:
1. **Pillows**: The humble pillow or floor pad is a simple, highly modular system allowing a wide variety of shapes and positions to be accommodated easily. Lay on it, prop your front up on it, stretch out a tail on one, lean forward and back. For thousands of years, humans have relied first and foremost on the modular pillow for resting, dining, entertaining (unless your lizard men eat all their non-reptilian guests...)
[](https://i.stack.imgur.com/5uY81.png) [](https://i.stack.imgur.com/vxA2a.png)
2. **Benches**: The fairly simple backless bench, combined with a table to lean over, will serve perfectly well, obstructing nothing.
[](https://i.stack.imgur.com/RqmbZ.png)
3. **Massage chairs:** For your more modern and civilized reptoids, I'd go with something to support all their parts while they recline in comfort. The best human equivalent is a massage chair, where people sit reclined forward while the rear of the seat is completely open. Low-tech versions of this can, of course, be made, and if they aren't made to fold and move like this one, the designs can be even simpler.
[](https://i.stack.imgur.com/4ypQD.jpg)
4. **Sitting backwards**: With few adjustments, most armless chairs can be sat in backwards leaning forwards, an ideal position for your lizards.
[](https://i.stack.imgur.com/R1i80.png)
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Something like this would probably work
[](https://i.stack.imgur.com/mGMwg.png)
where they would sit putting it between their leg, the same way a human would sit on a horse. The tail would freely accommodate on the read of the seat, and if they wanted they could lean forward, adopting the posture of an iguana standing on a rock.
[](https://i.stack.imgur.com/umECx.jpg)
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# Regular chairs
Or gamer chairs, if they are comfort creatures.
I am a programmer. I have many programmer friends and colleagues who hunch like smeagol, it's almost a job requirement. Some of them are over 6 ft tall.
Regular chairs seem to do for them, despite their constant nagging about back aches. I am almost sure they are human, so in their case it comes down to hunching like smeagol which is not natural for us. I swear to god I want to strap them sitting straight on their chairs just to get them to shut up. In the case of your lizardfolk, since its their natural stance, they should be fine.
Or...
# Bi chairs
Some years ago some guy complained on Twitter that his daughter wouldn't sit as a normal person. He made her a very uncanny chair so she could sit comfortably, as a practical dad joke. The internets, being what they are, dubbed the contraption a "bi chair - for people who can't sit straightTM".
Throughout the years new models have been designed by different companies, and now it's a thing of its own. Some models have a pad instead of a back support, which does facilitate hunching. Check the human in the top right corner of this image:
[](https://i.stack.imgur.com/NrrDS.jpg)
Source: <https://mobile.twitter.com/cosetthetable/status/1309624334806286342>
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I'm going to go with this guy (shamelessly cribbed from Runescape via Google Images) as a template:
I know, he's low-poly. It's not his fault, he was drawn that way. On the plus side he has the features we're after: digitgrade legs, reptilian (he's a lizardman, duh), hunched posture to account for the tail mass... he'll do. I'm going to call him Albert.
Now clearly Albert's kind would have some slightly different requirements for a seat than humans, elves and so on. There are a few obvious features that will make it basically impossible for them to ever have created chairs like we did:
* Tails don't mix with chair backs. Period. Oh, I know, some humans try to get inventive by putting tail slots or holes in the backs of their chairs, but we all know that's just not going to fly.
* Those feet do not sit flat, ever. They just don't bend that way.
* The skeleton isn't designed to sit upright, it is all arranged to lean forward.
* Differences in the pelvic structure mean that our lizardfolk are more comfortable sitting with their knees spread, kinda like a frat boy on a bus.
So let's start with the basics: stools. At some point in the development of seating every race goes from crouching to putting their butts on something - rocks, tree stumps, logs, whatever. Albert's people are no different here, but the articulation of the ankle and metatarso phalangeal joints as well as the structure of the pelvis means that they aren't comfortable just planting their feet in front of them. They're more likely to sit straddling a fallen tree with their hocks (those bits where the heels would be on a plantigrade walker) under their center of mass rather than sideways with feet forward.
Now the most comfortable stool for long-term sitting is one that lets your thighs be parallel to the ground with the feet - or toes in Albert's case - resting comfortably on the ground. In Albert's case that means a higher seat than humans with a similar hip height, because of the extra effective length of the lower leg. Sitting lower means folding the legs further back, but even at optimal height the hocks needs somewhere to go. Keep that in mind for later, it's quite important. And it's important that the thighs be parallel since the back of the thigh supports a portion of the weight. If it's not parallel then you get pressure points in the biceps femoris and it gets painful after a while. If you leave all the weight on the glutes you need lots of extra padding too.
So now that we've achieved stools, the next step is to add supports for the body to allow it to retain correct posture. For humans a fairly plain upright is all you need, since ideal seating posture mimics ideal standing posture from the waist up. For Albert, with that forward tilt to his torso, the best support would be a tilted front brace he can lean into, apparently at around 15 degrees. L. Dutch already posted a picture of a massage chair, so you know what I mean by this. Take out the head rest though, Albert doesn't need it - his cranial tilt is naturally high, so that if his body were vertical he'd be looking upwards. Also replace the tilted seat and leg rests, just focus on the chest support. Perhaps contour it a little to provide more support in the belly, if you're going for a more high-class look.
And for the final detail, the tail. Going from the image Albert's tail is supported primarily by the skeletal arrangements rather than constant muscle tension, so we don't need to worry too much about supporting it in the final model. If your lizardfolk have a droopy tail (poor guys) you might want to put a notch in the back of the seat itself to let the tail sit nicely. For Arthur and his buddies though, at most we'd put a small padded rear protrusion on the seat for comfort.
The end result is a flat horizontal seat slightly higher than the equivalent for humans, wide enough in the front to accommodate the slightly splayed seating style of the lizardfolk (that odd pelvic structure again) with a tilted front rest attached slightly forward of center of the seat via a narrow post, leaving plenty of room below the front rest for the thighs. Under the seat there is ample room for the hocks, either between the chair legs, as carved voids in a solid base or simply the result of a single supporting post attached to a wide base (like those god-awful spinning bar stools). Arm rests may be attached to the front rest as necessary, angled inwards for comfort or simply a horizontal shelf protruding from the front of the rest that will support the arms when folded across the chest, as though the one sitting were hugging the chair.
Mounting the chair would involve a forward squatting motion, spreading the knees around the front of the chair before bringing them back in to complete the seating process.
Of course you can add all sorts of features to the basic design for comfort or style. Moulded and padded seat, angled rests for the foot, fold-down front rests to make sitting easier, spikes and cuffs for restraint... uhm, that's for *special* use only, you should probably ignore those pages in the catalog. Albert is a respectable lizard after all.
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I am looking for a small list of Latin, Greek, or French words which would be most concise and descriptive of the qualities and functions of a pager-like device. The technical description of the device, as it might appear in a patent would be: "A portable, wireless, and paperless device for conveniently creating, holding, transmitting, and receiving, and displaying telegraph communications via the [BAUDOT code](https://en.wikipedia.org/wiki/Baudot_code)."
My world deviates from earth in 1891 but evolves a parallel technology. The society has these portable messaging devices similar to pagers (enhanced character sets and longer messages - 2,048 character limit and 'ASCII art' equivalent). The etymology cannot derive from modern concepts such as "radio" or "cellular telephone" because there is no Marconi (no word 'radio'), no Tesla, but they had both telegraph and wired telephones. The word 'wireless' was very popular - the hallmark achievements of both Marconi and Tesla.
The list will be used to evolve a colloquial in-world name for the device in the way the natural course of linguistics evolved our "TV"—from "Television," which evolved from the "Electric **Tele**scope" (from the Greek *tēle = far* and Latin \* vidēre = to see\*).
I only know a couple root words, such as the already mentioned "far", "gramma" for something written, and the French suffix "-ette" which commonly etymologizes small or portable things.
[Answer]
Living in France, I'll focus a lot more on the French part. Also, since reading is as much as important as hearing, I'll give some insights at how about it should sound (though the link provided also give audio records).
Then, I'll mark all pure French words in italic, well pure relatively to the topic. Parts that can be used relatively easily as word ends will start with "-" and ones as starter/prefixes will end with the same "-".
Finally, know that most word combinations are already used, so you'll have to do with it ^^'. Indeed, writing was -and is still, look at me writing :p - very important, so all sorts of words related to this has been made at some point and there's few to explore now.
## French word particles for writing
### -[script](https://en.wiktionary.org/wiki/script)
It is a simple as it sounds, the definition and way it is pronounced is about the same as in English. You can very easily prefix it, too : *description*, *inscription*, but more interestingly *téléscripteurs*. Those last ones were actually used for machines to communicate over long distances. It is not told or written anymore nowadays so it'll surely sounds old timey, especially to young people.
### *-[impression](https://en.wiktionary.org/wiki/impression)*
It's the French for "printing", sounds a bit like "impress" mixed with the end of "atten-tion".
You can make it a "maker" of prints by replacing it with *[imprimeur](https://en.wiktionary.org/wiki/imprimeur)*, like *téléimprimeur*. *Imprimeur* is more old style, as today it defines the companies that print in large quantities documents such as newspapers. A variant of *imprimeur* is *[imprimerie](https://en.wiktionary.org/wiki/imprimerie)*, it has mostly the same meaning.
A more modern sounding word would be *[imprimante](https://en.wiktionary.org/wiki/imprimante)*, just means a computer printer. The "mante" part should be sound about like the start of "mantis", cut just before the "is".
### *-[rédacteur](https://en.wiktionary.org/wiki/r%C3%A9dacteur)*
Or with silly English words, sounds like "ray'd ack'ter". A *rédacteur* is a writer, often related to journalists and in general document writing, compared to *écrivain* from *écrire* which is solely for novelists and the such.
### *-[Compositeur](https://en.wiktionary.org/wiki/compositeur#French)*
Its counterpart verb *[composer](https://en.wiktionary.org/wiki/composer)* is sometimes used in printing industry, hence I let it here.
It's at its root someone who organize objects into something bigger, like notes into music or letters into sentences. It's the composer in English and the beginning is spelled the same, and the rest "almost" like "l-ighter". Since it has strong relationship with music, note that it tends to be more elegant and artistic than the others.
I don't remember seeing it used as a part of another word, but I guess you could make use of it like with some *télécompositeur* or in more English-like telecomposer. Doesn't sound too shabby.
## French word particles for linking
### *Télé-*
Well, *téléporteur, télégraphe, télévision, téléphone*... I think you don't need much to understand how widely it is used to mean "from a distance", or what the above words mean :).
### Trans-
"Trans" is used to mean a way to move something from one place to another, to... Transmit :p.
See the kinds of words related to communication you have : *Transmettre*/transmit, *transcripteur*/transcriber and *transpondeur*/transponders for instance.
### Inter-
It's the prefix to relate things one to another. It's actually used in French to tell the world wide web (*internet*). As such, it's better used in conjunction with the things you want to intertwine together, rather than its content. You might need some thoughts on what would be your communicating box to people, therefore.
To give you a modern usage to reach people inside buildings : *interphones*/intercom.
[Answer]
Sounds like tweets. I'd suggest TeleText, TT. You could call it TeleMail or TeleNote, TeleWrite or TeleWriting. Even TeleCopy; if one focuses on the idea of "copying" what you wrote elsewhere.
In the same "copy" sense, I can make a case for "Twinner"; making a twin (=copy) of what I wrote on my device, on your device. So, Twin me back. Twin me when you get there.
Or just use "Copy", like they say on Radio; "Do you copy?" You can make it clear from the context this is just text messaging.
>
> John's copier vibrated, he extracted it from his pocket to read the screen. From Linda. "I just got a copy from Brenda, she said Alex never showed up."
>
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> John typed back, "OK. I'll try the canyon. Copy me if you hear anything."
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[Answer]
1. As far as anybody knows, the word *television* is a direct macaronic compound of Greek *tele-* "far" (as in *tele*-scope, *tele*-graph and *tele*-phone, all of which are correct Greek compounds) and Latin *vision-* (which means what you think it means).
2. Making up classical-sounding words is an endless game:
* If we like macaronic Latin-Greek compounds, why not *portagraph*, from *portable* and *telegraph*; after all, that's what it is, isn't it? Shortened in everyday speech to *graph*, of course, as we shorten mobile telephone to phone.
+ Or Greek-Latin *telescriptor*, which would of course be *une téléscriptrice* in French.
* Or purely Greek, *perigraph*, from *peri-* "all around", as in *peri*-meter and *peri*-phery. (The word *periphorêtos* ([περιφορητός](https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dperiforhto%2Fs)) actually means "portable" in Greek.) (The more normal Greek word for "portable", *agôgimos* ([ἀγώγιμος](https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Da%29gw%2Fgimos)) does not lend itself to euphonious compounds.)
* Or, historically atested, [teletext](https://en.wikipedia.org/wiki/Teletext) (remember it?) and [telex](https://en.wikipedia.org/wiki/Telex). (Telex was introduced commercially between the wars, in Germany of course; and yes, telex worked over wireless too.)
* Or, if we prefer fancier Greek, something like *logagremon*, from *logos* "word, sentence, story" and [*agremôn*](http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Da%29gremw%2Fn) "hunter, catcher". Shortened to L.A. in everyday speech, of course.
* Of the more normal Greek words for "hunter", *agreutês* ([ἀγρευτής](https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Da%29greuth%2Fs)) could give *panagrete* /ˈpænəgriːt/ or *panagry* "universal catcher", or, most sweetly, *paragrete* /ˈpærəgriːt/, which would mean something like a "catcher who stands beside somebody", a "side-catcher".)
Most sweet of course because it alludes to the [Paraclete](https://en.wikipedia.org/wiki/Paraclete). (Speak about making a late career. The word normally meant "advocate" or "helper" in Greek. Christianity promoted it to refer to a hypostasis of God.)
* Or, using an actual Greek word, a *grammatophore* ([γραμματοφόρος](https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dgrammatofo%2Fros)), which properly means a "letter-carrier", a "courier".
3. But the truth is that we actually *have* a word for a small, portable, wireless, and paperless device for receiving and displaying telegraph communications": a [pager](https://en.wikipedia.org/wiki/Pager). And yes, two-way pagers with tiny keyboards did exist back in the day when pagers were a thing. If the bloody thing **is** a "pager-like device", why not call it a pager? Why make it harder for the readers to read the story?
4. Guglielmo Marconi did not invent the *word* radio to refer to radio.
The oldest known application of the ancient Latin root to wireless communications, as far as the Oxford English Dictionary and the [Trésor de la langue française informatisé](https://www.cnrtl.fr/definition/radioconducteur) know, belongs to [Édouard Branly](https://en.wikipedia.org/wiki/%C3%89douard_Branly) who used [*radioconducteur*](https://en.wiktionary.org/wiki/radioconducteur) (in French, radioconductor in English) back in 1897 to refer to what we call a [coherer](https://en.wikipedia.org/wiki/Coherer). The OED even has a citation from 1898, refering to *"M. Branly, whose ‘radioconductor’ or ‘coherer’ is used by Marconi in his wireless telegraph"*.
* Which means that the story can freely use *radio mail* to refer to the epistles sent by radio. Shorted to first r-mail and then eventually to just mail, as in real history.
[Answer]
#### A Historical Perspective
**Voc-o-Graph** (eventually just vocograph or even VG) is a name to consider based on historical models.
In real world history, back in the day, people that went around waking on call workers might colloquially have been termed "callers". You can find recordings of Harvey & Shirkey's Railroad Blues:
>
> I hear somone a-knockin, knockin at my front door;
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> Hear somone a-knockin, knockin at my front door;
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> It's a doggone caller, callin me for half past four.
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>
>
This usage dates in minstrelsy to the early 20th century and almost certainly in railroad (etc) usage to an earlier period than that. Example from a Casey Jones ballad:
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> Caller called Jones at half past four
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> He kissed his wife at the station door.
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>
>
voc- is the Latin root for calling and we see it in phrases like vox populi (voice of the people) and words like convocatio, a calling together.
Graph and scribe have long been associated with writing, and especially the former with the relatively newly invented office machine sector of which the typewriter was the centerpiece.
[](https://i.stack.imgur.com/dvKAE.jpg)
Since your device somehow writes or displays the caller's message, the Greek root γράφ- / graph- meaning write is always a good choice. We see it in words like telegraph (distance writing) and graphic artist (an artist who deals, literally, in engraved imaged and words). scrib-, the Latin root underlying scribe and scripture, is a good alternate.
There are loads of trade names and brands this kind of tech can generate with these roots and associated marketing forms like the pseudoGreek suffix -a/orama (actually derived from the Greek horama).
You might find an advertising war between VG-Rama and Vocograph with Vok-ette, VoGraf and TeleVox nipping at the big boys' heels.
[Answer]
The obvious answer would be "teletype". I'd vaguely assumed there would be more unix nerds on here (because of what [TTY](https://en.wikipedia.org/wiki/Tty_(Unix)) means) but maybe they're all busy.
[Radioteletypes](https://en.wikipedia.org/wiki/Radioteletype) were very much a thing in the real world... they even worked using Baudot code (note that it isn't all-caps... M. Baudot was a person, not an acronym). They evolved from [teleprinters](https://en.wikipedia.org/wiki/Teleprinter) (~1849). I'm not entirely sure where the name "teletype" came from... there's a reference to it in a news article about one of the earliest demonstrations of sending text over radio: [Typing in airplane received by radio](https://timesmachine.nytimes.com/timesmachine/1922/08/10/99054387.pdf) (NYT, 1922).
Now, I know you said
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> The etymology cannot derive from modern concepts such as "radio"
>
>
>
but I take some issue with that... obviously "cellular" is a fairly technology-specific term, but radio just comes from the latin for "[ray](https://en.wiktionary.org/wiki/radio-#English)", and its appearance in the language isn't entirely implausible. If you'd prefer a more purely Greek root I could suggest *aktis* (which gives us words like [actinic](https://en.wiktionary.org/wiki/actinic) though I can't say that "actiteletype" quite trips off the tongue as well as its real world counterpart. **Actitype** starts coming close though, I'd say... plausibly the name of an early commercial model or manufacturer, at least. Though the root still means "ray", it is pleasingly similar to the Latin root that gives us "[active](https://en.wiktionary.org/wiki/active#Etymology)" which implies a certain amount of mobility.
For a less format term, take a look at the history of radios: we have the cumbersome "handheld transceiver" which gave rise to the ever popular [walkie-talkie](https://en.wikipedia.org/wiki/Walkie-talkie#History) (though the phrase "[handie-talkie](https://en.wikipedia.org/wiki/SCR-536)" came first). I've got to admit that "*walkie-typie*" seems kinda ridiculous to me, but it isn't any more ridiculous than walkie-talkie and that phrase still seems to be with us today ~80 years after its debut.
Handheld transceiver may be abbreviated to HT, and so the actiteletype may reasonably be shortened to AT, which is a nice simple and easy to say initialism.
Finally though, to avoid the "acti-" neologism entirely you might simply resort to "telememo" which will at least have a meaning more readily guessable by your audience as a way to leave a "remote note". I'm not sure when the first use of "memo" (as an abbreviation for memorandum) came about so it may be a little anachronistic, which may or may not bother you. It appears in the real world as an [Australian email service](https://webarchive.nla.gov.au/awa/20141210013314/http://pandora.nla.gov.au/pan/11870/20141210-0856/www.ascilite.org.au/ajet/ajet2/kember.html) in the 80s, and a feature of some casio watches, sp if you wanted a term without any real world counterpart then actitype is the best I have to offer, sorry.
[Answer]
**Baudotype.**
It is the Baudot wireless device or a direct descendant. It would be the "Baudotype", like the daguerrotype was named after Daguerre or pasteurization after Pasteur.
British would call them Baudos or Boddos or Bods.
[Answer]
If the device is invented in France, on the wave of the successes of the telegraph, I believe it is a virtual certainty that it will be called something like *télécrivant* (seeing as how *telegraphe* is already taken; also, *écrire* is more clearly understandable by the wide public).
The obvious abbreviation would be *télé*. By the same token, maybe *téléscripteur* or *scrip*.
Another possibility could be *port* or *portéc* - from the more awkward *machine à écrire portative* or *portatif*, portable typewriter (nowadays, *cellular telephone* has contracted to *cellphone* and finally *cell*, completely dropping the *phone* part).
(Back in the days, *portatif* (orgue portatif) was a kind of [portable organ](https://en.wikipedia.org/wiki/Portative_organ) that could be operated one-handed).
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[Question]
[
Alice the mermaid and Bob the human have been dating each other for quite some time, and being young adults filled with love and copious amounts of hormones the two of them want to take their relationship to the next level by engaging in intercourse. **However, there's a big problem in the young lovebird's way: how can the two of them find a position to mate in that is comfortable enough for both parties to enjoy the act?**
The mermaid may not be comfortable laying on her back on land (especially if she has some sort of dorsal fin) but might be little more than dead weight if she were on top, whereas the human is likely to drown if they tried mating in the water. The mermaid may be more comfortable swimming, but it would be hard for the human to focus on mating and enjoying the experience while treading water. Mating in a standing position without any support is also uncomfortable for most humans and many men report it difficult to maintain an erection or complete the act of sex in such a position (there are clinical notices about this on public health sites but I'm not linking them to keep this as SFW as possible), possibly because of muscular tension in the pelvis and legs while standing or differences in blood pressure when standing. Mating in the surf zone would likely be annoying because they would be constantly bombarded by surf and the mermaid might end up with sand in her gills.
Other parameters to the question:
* The typical mermaid problem isn't an issue here. Mermaids have male and female reproductive organs similar to dolphins (and similar attitudes on how to use them)
* The mermaid can breathe air and can survive out of water for a decent amount of time, but also has gills allowing her to breathe water
* The mermaid cannot transform her tail into a pair of human legs and walk on land that way
* The mermaid may or may not have a dorsal fin. It might end up being absent if its too much of a hassle for the story, but most marine animals do tend to have one
* The goal of the activity is for it to be mutually pleasurable for both participants. Non-penetrative or otherwise alternative methods of intercourse like oral sex would be much easier to achieve, but these two want to take it all the way.
[Answer]
**There isn't a problem**
All they have to do is find a suitable shelf in warm shallow waters. The human can stand with their head out of water. The mermaid swims upright.
[](https://i.stack.imgur.com/5dzAI.png)
[](https://i.stack.imgur.com/IZHyw.png)
[Answer]
**Scuba-diving**
If they're truly in love, I'm sure Bob would be willing to invest in some scuba-diving lessons and equipment. As for the method, online YouTube videos show that Dolphins mate face-to-face.
[](https://i.stack.imgur.com/bxr7o.png)
[Answer]
I'm not going to diagram them up - I couldn't find anything exactly matching your requirements on deviantart but rule 34 should still apply and I guess I'm not looking hard enough to find these images.
Basically if her "tail" can't split then replace this with "knees together" in current human sexual reproduction. You're basically limited to positions where the female's thighs and body are at a right angle. There are lots of choices where female knees are together but body bent, 2 of the most common involve entry from behind, which may or may not work with the relevant body structure of your mermaid.
* My first thought would be mermaid bent over some furniture, tail on ground, human male standing straight behind. Male could even grab to dorsal fin for leverage. May need a stool or stepladder depending on relative heights and structure of tail. With an above ground pool may help her breathe and regulate temperature.
* Alternatively, male sitting on edge of bed, mermaid sitting on lap facing away. Male leans back far enough to avoid the dorsal fin.
* Or, if sexual organs are totally inaccessible from the rear so those positions are no good, and the only access is upward from her front without her "thigh fin" bending backwards; everything gets a good lube, Male lies down on bed legs spread and slightly lifted, she lies on him higher up, and she slides down until penetration. Dorsal fin remains free and facing upwards.
If either of those proved unworkable a quick trip to the hardware store to rig up some contraption and position all parts in the perfect position should solve all problems. If your arranging cross-species sex youre probably kinky enough that you're ok with a little light bondage to help accessibility.
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[Question]
[
I'm building a medieval-high-fantasy world and I want it to have two suns. I'd like it to make it **somewhat realistic at least as far as seasons and light/biomes go**, while the actual feasibility of this kind of binary system can kinda be handwaved away. I also would like the two stars to be different, in the following example I opted for a yellow-reddish sun and a white one.
I'll make a few assumptions:
* the Earth has an 8-shaped orbit around two stars, **A** and **B**, as detailed in [this answer on Physics.SE](https://physics.stackexchange.com/questions/31201/might-a-planet-perform-figure-8-orbits-around-two-stars/67260#67260)
* the planet's orbit is on the same plane as the two stars
* the Earth's axial tilt relative to the orbit's plane is the same as our current one
* **A** is a white star similar to Altair (~1.75M⊙, ~10L⊙)
* **B** is a yellow dwarf (~1.25M⊙, ~1.2L⊙)
* the two stars are roughly distant 3 AU from each other (I'm not really fixated on this, you can change this value as you wish if it helps in any way)
My first question is: **would this configuration be tolerable and able to support life on the planet, or would there be problems** (e.g. the white star being far too luminuous)**?** If not, what are some things I could change to make it viable and still have two suns that look different?
If it is viable, here's my main questions:
* **what would seasons and average temperatures be like on the planet?**
My best guess is that each hemisphere would have two summers and one winter per year.
E.g. the northern hemisphere would be in summer when the planet and the stars are aligned as A-B-Pl, would be in winter when they're aligned as Pl-A-B, and would be in strong summer when they're aligned as A-Pl-B (during which both hemispheres are in summer).
I also suppose that the planet's revolution speed would be at its slowest when the planet is between the two stars.
Would this setup make any areas on Earth less habitable for humans? more so?
**EDIT**: I'm only interested in how it would affect human life (climate + how they experience seasons) and in **keeping suspension of disbelief**, **I don't want a 100% realistical solution** completely rooted in physics, I just want help in making it so that I can explain the seasons and the look of the stars to a group of TTRPG players without them raising an eyebrow :)
As far as the *biomes and temperatures* part goes, everything I ask for is something along the lines of "the planet will have a mega-summer in the northern hemisphere when it's located XXX, reaching average temperatures of roughly YY°C (+Z°C than what we see on Earth)". Even a simple percentage increase/decrease in temperature is totally fine.
[Answer]
There's a lot of questions here - so I'm just going to focus on your main one about "what are the seasons and days like?" (the mods will probably make you edit your question down to this shortly anyway.)
That said I believe your planet will be habitable but on the hot side, I haven't done the calculations, because there are mitigation strategies available to you as an author - big mountains casting shadows, layers of ash from a permanently erupting volcano, white fluffy cloud layers reflecting sunlight, etc. If you run the physics and it's too hot, cool it down.
Here's the orbit and axial tilt as I understand it.
[](https://i.stack.imgur.com/c2FWC.png)
The relationship between the axial tilt and the plane is important here. I have guessed a relationship here - north pole pointing to the right, but you can tweak it to change things.
You have 8 seasons over your "Year" in the Northern hemisphere:
* (A) Spring. ~18 hour days.
+ One sun rises, then another ~6 hours later.
* (B) Mega summer. 24 hour days.
+ One sun rises when the other sets.
* (C) Fall-lite. ~18 hour days.
+ One sun rises, then another ~6 hours later.
* (D) Warm winter. ~10 hour days.
+ The suns rise at about the same time.
* (E) Warm-to-hot spring. ~18 hour days.
+ One sun rises, then another ~6 hours later.
* (F) Mega summer again.
+ One sun rises when the other sets.
* (G) Fall. ~18 hour days.
+ One sun rises, then another ~6 hours later.
* (H) Mild summer. ~13 hour days.
+ The suns rise at about the same time.
Southern hemisphere is a bit cooler but very similar:
* (A) Spring
* (B) Mega summer. 24 hour days. Slightly cooler than Northern.
* (C) Still hot a mild fall.
* (D) Mild summer. Warmer than Northern's "H" however.
* (E) A hot-to-mega-hot spring.
* (F) Mega summer again.
* (G) Fall
* (H) Winter.
The southern hemisphere will on average be cooler, and have the coldest winter of anywhere. But the southern hemisphere also has 5 adjacent seasons of heat.
Tides will be weird. You'd have twice daily high tides at B/F, and once daily double-high tides at H and D. Tides would be once daily but uneven lengths (long high, short low) at A, E, G, and C.
[Answer]
I don't think your orbit is stable. What may work is to have a plant orbiting a small star in an eccentric orbit, while the small star orbits a larger brighter star in much larger eccentric orbit.
Now you have a wildly fluctuating climate that depend on:
* Period around the small star.
* Tilt of the planet compared to plane of orbit.
* Rotational period.
So far no problem. This is much like earth, but with faster seasons due to a closer orbit.
* period of of small star around large star.
* tilt of planet orbit relative to plane of small star's orbit.
On Earth at temperate latitudes there is about a 2 month delay between the astronomical seasons and the climatological seasons. E.g. The least sun is on the winter equinox, 22 December in the Northern hemisphere, but the coldest month is usually February.
Similarly daily variation is going to be dependant on how long the day is. If earth had 48 hour days, the daily variation would be brutal. It won't be linear with day length, as I would expect cloud formation to increase with longer days.
Longer day length will also decrease coriolus effect which should make storms larger in extent, but also decrease the temperature difference between equator and poles.
A short fast orbit around the small star will mean that seasonal variation will be smaller. But an eccentric orbit means a long time in the cold end of the orbit and a very short time near the star. The more eccentric the orbit, the more extreme the difference.
The orbit around the bright star can act as a multiplier.
At this point my mental model of the spherical trigonometry fails me. I think you get a super roasting when the plane of the planet's orbit has the bright star in the same plane.
Anyone know of online models -- simplified climate models where you can change the plane of orbit etc?
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[Question]
[
I'm trying to come up with ways as to how a ship could travel places with a very low number of people (like 4 crewmen). One of the ways I like for how to do this is to have large sea creatures harnessed and used like horses.
How big would a sea creature need to be to be able to tow a cog about 25 meters in length over long distances in an ocean? (Or how many creatures?) Any ideas about possible domestication and feeding are welcome. It is a fantasy world, but I don't want the answer to be some sort of magic.
[Answer]
I think the most important property is a suitable body for the harness connecting the cog to the tug (?) animals, or swim team -- sounds like a bad pun.
The cog will need to be a little extra buoyant in the bow to oppose the downward force generated by the swimming monsters.
The dermis of most aquatic creatures is not going to accommodate a hemp rope looped over their bodies since it would rub and wear too much. And, fish don't have shoulders so it will be a challenge to make a yoke that will efficiently transfer the fishes thrust to the ship.
For those two reasons, I can see giant sea turtles as being draft animals. The yoke could be mounted to their shell without causing them pain or distress. Then, all the yokes could connect to a single tow cable.
If turtles are not attractive, then I could imagine a yoke that conformed to the fishes face, and the fish would swim into it to pull the ship forward. Alternatively, these yokes could be mounted anywhere on the ships hull. The inner surface would be a soft felt that protected the piscine dermis from rubbing -- like moleskin. The body would wriggle and friggle to produce the thrust.
I think as long as the creatures are large enough to overcome the friction between the water and the hull, and the waves and the hull, then they'll be able to accelerate the ship to its best speed.
Another thought, giant remora-like fish attach themselves to bottom of the copper plated hull and move the ships around, except these actually swim rather than try to ride for free.
Now, ideas about domestication and such until a specific species is identified.
[Answer]
**If your ride is as smart as you are, you are just a passenger.**
[](https://i.stack.imgur.com/kVIqA.jpg)
Your crew has nothing to do because their boat has no sails, rudder or oar. It is moved by a giant intelligent mosasaur-like creature. Certain individuals of their kind have an arrangement with onshore humans: they ferry passengers to a destination and in receive get things they need - land meat, and possibly other things as well.
Would your passengers trust themselves to a giant sea predator who speaks to them in a squeaky high voice up through the hull of the boat? And what kind of predator takes this job? A bitter old bull past his prime, maimed in battle, living just to eat? A young female, smarter than the rest, looking to use her smarts to bulk up on land meat? And if they encounter another of her kind at sea, what then?
[Answer]
One problem you'll have with believability in this is that most sea creatures are built for efficiency -- dolphins, swordfish, and barracuda for speed, sharks for energy conservation and feeding efficiency, whales for efficient filter feeding or prodigious deep diving -- not for pulling force.
That said, trained dolphins are on record and film pulling small boats. Generally this is an adult dolphin, 6-8 feet long, pulling a tiny dinghy suitable for 2-3 adults at most, and they don't do it for long and seemingly can't pull it much faster than a human can row. Further, this activity doesn't scale well; the drag of a 25 meter cog is hundreds of times that of a 3-5 meter dinghy (not to mention it's far heavier, so takes more energy to accelerate).
A useful scaling factor is to examine the sail area required for the sizes of the vessels -- a small skiff needs a few square meters; that cog needs a few hundred square meters to get anywhere in a reasonable time. That means it would need the power of a few hundred trained dolphins -- and a pod that size, if free to come and go in order to feed themselves, would eat everything they can catch over a hundred square miles as they passed.
[Answer]
Power may be estimated as proportional to speed x transverse cross-sectional area. Or, given animals of similar proportions, length^2 x speed. And everything else being equal, bigger fish are faster than small fish (for the same hydrodynamic reason bigger ships can travel faster than small ones). So the [blue whale](https://en.wikipedia.org/wiki/Blue_whale) seems the best bet. It is fast for a whale, efficiently streamlined, and 100' or so long. There are closely related whales (the rorquals) of [assorted smaller sizes](https://upload.wikimedia.org/wikipedia/commons/3/37/Rorqual_Cladogram.svg), suited for smaller ships.
You would need to have a long towline, for three reasons: to ensure a shallow tow angle (compare [horse-hauled barges](https://en.wikipedia.org/wiki/Horse-drawn_boat)), to absorb jerking around from wave action, and to minimize drag from the ship being pulled through the whale's wake. The towline would need to be taken in (shortened) presumably with a capstan, and speed reduced for maneuvers such as entering and leaving port.
But with a long towline, another problem rears its ugly head: how to drive and control the whale. Unless a magical control of some sort were used, the driver would probably need to accompany the whale, like a mahout, rather than staying on shipboard.
The biggest problem is the feeding. Even if you had two whales working and feeding in shifts, you would be dependent on suitable plankton. This could be leveraged to provide additional plot complications--your ship could only follow routes where good grazing were available.
Now, if your world included real big turtles. . . Turtles feed on jellyfish, which could conceivably be harvested by the ship with trawl nets, and fed to the turtle. IIRC, jellyfish usually come to the surface at night, so the ship would slow down at night and deploy nets as needed. And it is easier to conceive of a mahout on a turtle than on a whale.
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[Question]
[
Suppose you were puttering around the solar system and came across the remains of a luxury passenger vessel, the intergalactic equivalent of the Titanic, adrift about one [AU](https://en.wikipedia.org/wiki/Astronomical_unit) from the sun. The hull was shattered, with thousands of souls aboard living in a comfortable, [shirt-sleeve environment](https://en.wikipedia.org/wiki/Shirt-sleeve_environment) before meeting a sudden and horrible death. But instead of freezing seawater, the human remains were left entombed in outer space. What do they look like, after 73 years (the same number of years between the sinking of the Titanic and its discovery in 1985)?
* Would they be completely intact? Merely recognizable? Atomized?
* What tissues would remain? Would they be discolored? Scarred? Burned?
* Would their bodily fluids have frozen? Boiled away?
* Would they be stiff, brittle, or pliable? How would zero gravity pose them?
* Would they be distorted in shape, e.g. tend toward becoming spherical?
* Would their clothes be preserved, tattered, or obliterated?
* Would the bodies be completely still, or would they be rotating? Perhaps slowly and in unison (creepy!) due to angular momentum?
Looking for the realistic, gory details.
[Answer]
Well, strange as it may sound, space has some aspects which help preserving a body... let's look at it more closely.
**Vacuum**
The extremely low pressure found in space means that any liquid will quickly evaporate. As mummies in the desert hint, lack of water is a good way to preserve organic matter. The corpses will be shrunk due to the loss of water, but will not be rotten. I expect some peculiar behavior of eyes, as they are mostly watery. Bacteria normally taking care of decomposition need water and oxygen, two items which in space are pretty rare.
Since a human body is about 60% water, the corpses, after losing all their water, would weight about 60% less. So, a 90 kg once alive astronaut would be a 36 kg corpse.
**Radiation**
That can be nasty, especially on organic matter. But the corpses, being inside, will have some shielding from direct exposure to radiation. They will likely show some darkening due to photocathalyzed reactions, and maybe embrittlement of hairs due to the combined dehydratation and radiation exposure. Their clothes would be probably bleached white (or going in that direction).
If you want some visual reference of how they might look like, take some bleached shirt and put it on Oetzi.
Being almost at rest with respect to the ship where they were, I don't expect big changes in their position. Maybe some slow drift, with movements induced by the evaporating gases in the very first moments of the incident.
[Answer]
>
> Would they be completely intact? Merely recognizable?
>
>
>
More like "barely recognizable". You'd basically have freeze-dried mummies. The answer from @L.Dutch has mentioned [Ötzi](https://en.wikipedia.org/wiki/%C3%96tzi), and that's probably not too far off, although I don't think radiation would be a huge factor since I'd expect the inside of a spaceship to be appropriately shielded. However, if they are exposed to sunlight via windows or holes in the hull, they might indeed be darkened with bleached clothes.
As for the positioning of the bodies, they would most likely not be floating around.
You wrote that "The hull was shattered", which implies an impact, which would leave the spaceship rotating. In fact, any kind of hull breach would almost certainly lead to rotation due to repulsion from the escaping atmosphere. And even a very slow rotation would eventually deposit all loose objects in each room on the surface farthest away from the axis of rotation (or stuck on the way there).
However, the force keeping them there would, for a slow rotation, be minuscule. So even a light touch could overcome it and cause a body to flot around for a while.
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[Question]
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There is an empire expanding from the Netherlands to Western Russia, the empire is enthusiatic about turning rivers into canals for transportation.
They don't care about the environment, they just need the closest thing to a railway to transport goods and soldiers around. Assuming 14th century technology and "limitless resources" how would they go about connecting, say, the Rhine to the Danube? What about the Elbe, Oder and the Vistula to the Danube? Also, what about Neman, Daugava, Volga and the Dnieper, maybe the Don too.
I know that connecting the Rhine and the Danube is possible since it has been done today, though not directly, and I'm fine with that if it makes possible to connect Germanic and Slavic territories. And more than that I do like to know how it would be done (but please explain it in layman's words).
If it's not possible, maybe because some rivers come from the Alps and other from the Carpathian Mountains or something of that nature, do elaborate on it, I do love to read about it.
Also bonus points if you can say something about the feasibility of such empire, maintaining control of such vast lands through the fast movement of troops through man-made canals.
[Answer]
You need a few things to build a canal:
1. locks, as in locks for ships, not the thing that closes doors. These were first built around the described time, so those are no problem.
2. the ability to move massive amounts of soil. Surprisingly, it was only recently that man-with-bucket stopped being the most efficient alternative.
A famous example is the [White Sea - Baltic canal](https://en.wikipedia.org/wiki/White_Sea%E2%80%93Baltic_Canal), built using Gulag labour in the 50s. This was a labour force of 100.000 so those are the numbers you'd be looking for.
Note that by medieval standards that is a ludicrous number of people. And assumes that the soil-removal teams can keep up because [mining rails](https://en.wikipedia.org/wiki/Mine_railway) won't be invented for another couple hundred years. But a canal like that, through the lowlands, is fairly easy business. The maximum height they reach is 103 meters, the rhine-danube canal is quite a bit higher at 170 metres elevation level. The Russians also made good use of lakes while the Germans had no such luxury.
Also look at the [Corinth Canal](https://en.wikipedia.org/wiki/Corinth_Canal), several empires including the Romans attempted them but it was only finished in the 1890s.
But for the best example by far look at the [Fossa Carolina](https://en.wikipedia.org/wiki/Fossa_Carolina), a canal built in 793 under orders of an actual emperor. 2km long and a 100m wide linking tributaries of the Danube and Rhine. It is unknown if it was ever finished but the fact that this is debatable indicates that it is not a stupid idea.
So, is it possible: well..it is not impossible.
But what you describe is going to be a ludicrously expensive effort in both manpower and materiel. Constructing all the cathedrals in Europe will look like peanuts in comparison. Canals are famous for bankrupting anything who even plans to start one and even a single one of the canals you named could bankrupt your empire.
But a few canals in specific locations that can assist you in logistics? yeah, sure.
[Answer]
Romans were not so fond of connecting rivers, but they were great road builders, to move their troops and goods around the empire.
They were pretty straightforward on this: if they wanted to go from A to B and there was a mountain in between, they cut through the mountain when it was possible.
Their cutting technique involved fire and vinegar: light a fire on the rocks, cool them down with water and vinegar, remove the enbrittled rocks.
By using this method the Romans were able to connect Rome to all the cities of their empire, crossing Alps and Apennines, therefore in principle if you have large mass of workers, fire and vinegar you could be able to replicate the process.
The only problem when dealing with rivers is that water, as opposed to horses and walkers, cannot go uphill on its own.
You would need a system of locks to cover the height differences, and maybe use ground transport on certain sections.
Therefore the answer to your question is: yes, it could be possible, having the knowledge of Roman engineering and a large workforce. Also, build ships suited for shallow water, like the Viking drakkars. It will save digging effort.
[Answer]
I note that boats on rivers and canals can vary in size, and are often quite small. Even ocean going ships could be very, very tiny a few centuries ago.
The Popham Colony in modern Maine built a 30 ton pinnace, the *Virginia*, in 1607-1608. The 46 colonists abandoned the colony in October 1608 and sailed back across the Atlantic in the terrifyingly small *Virginia*. *Virginia* made a round trip across the Atlantic in 1609 as part of the "Third Supply" fleet to Jamestown, and sailed to Virginia again in 1610.
<https://en.wikipedia.org/wiki/Virginia_(pinnace)>[1](https://en.wikipedia.org/wiki/Virginia_(pinnace))
The English ship *Squirrel* of only 10 tons made at least two transatlantic voyages in the 1570s and 1580s before disappearing on the 3rd voyage in 1583.
<https://en.wikipedia.org/wiki/English_ship_Squirrel_(1570s)>[2](https://en.wikipedia.org/wiki/English_ship_Squirrel_(1570s))
in Canada, the Red River Expedition of 1870 had to transport a thousand men, and supplies including cannons, hundreds of miles through a wilderness. Part of the trip was made in many canoes, which were portaged between various watersheds.
In the 17th century the English colonists in Maryland around the Chesapeake Bay and the Dutch colonists around the Delaware Bay carried on illegal trading and so couldn't sail by sea from bay to bay. So ships with their cargoes sailed up creeks from one bay as far as they could, and then were put into giant oxcarts and hauled for miles to the headwaters of creeks emptying into the other bay.
Some of those ships were only for coastal voyages but others were capable of transatlantic voyages.
The great city of Constantinople, "The City of the World's Desire", had a massive iron chain that was used to close off the Golden Horn from enemy ships during attack. A Russian chronicle claims that attacking Russian vikings in 907 hauled their small ships on land, attached wheels, and pulled them overland to enter the Golden Horn despite the chain, but Byzantine chronicles don't mention that attack.
<https://www.history.com/news/globetrotting-vikings-the-quest-for-constantinople>[3](https://www.history.com/news/globetrotting-vikings-the-quest-for-constantinople)
<https://www.slavorum.org/forum/topic/slavic-vikings-rus-and-varangians/>[4](https://www.slavorum.org/forum/topic/slavic-vikings-rus-and-varangians/)
And viking raiders and traders often carried boats and/or ships overland from one river system to another.
And the Ottomans did more ships overland into the Golden Horn during the seige of 1453.
<https://www.quora.com/Did-the-Ottomans-really-move-ships-over-land-during-the-conquest-of-constantinople>[5](https://www.quora.com/Did-the-Ottomans-really-move-ships-over-land-during-the-conquest-of-constantinople)
And then there is the *Diolkos* the pathway, sort of an early railroad, to carry ships across the Isthmus of Corinth during Classical times.
<https://en.wikipedia.org/wiki/Diolkos>[6](https://en.wikipedia.org/wiki/Diolkos)
Building canals to connect rivers to avoid portages is a good idea, but not totally necessary.
In 793 Charlemagne tried to dig a two kilometer long canal, the *Fossa Carolina*, from Truechtlingen to Weissenburg, connected the Schwabian Rezat river to the Altmuhl river, and thus the Rhine-Main and Danube watersheds. This may have been for commercial and/or military purposes. It is unknown whether this canal was completed and operational, but it was the inspiration for modern canals connecting the Rhine and Danube watersheds.
<https://en.wikipedia.org/wiki/Fossa_Carolina>[7](https://en.wikipedia.org/wiki/Fossa_Carolina)
From what I've read, there were a number of vast earth moving projects in Europe in ancient and medieval times, including the Antoine Wall, Offa's Dyke, the Dannewerk, and the Great Fence of Bulgaria.
So building a Rhine-Main-Danube canal would not be totally out of scale in a medieval Europe.
With a medieval Rhine-Main-Danube canal one could sail and row and be towed from the Netherlands to the mouth of the Danube and sail across the Black Sea, and maybe travel up the rivers into Russia.
The Sea of Azov empties into the Black Sea, and the Don River empties into the Sea of Axov. The 101 kilometer long Volga-Don Canal connects the Don River with the mighty Volga River that empties into the Caspian Sea. The Volga River and its tributaries are connected by canals to the Baltic Sea and the White Sea.
I know that in modern Europe there are canals connecting the Rhone and Mediterranean with the Rhine, the Rhine with the Elbe, the Elbe with the Oder, the Oder with the Vistula, the Vistula with the Neman, and the Bug (tributary to the Vistula) with the Dneiper River that flows into the Black Sea. But some of those canals have locks and other modern technology that might be difficult to duplicate with medieval technology.
Another important modern European canal is the 98 kilometer long Kiel Canal across the Jutland Peninsula, allowing ships to sail from the North Sea to the Baltic Sea without having to sail around Jutland. A medieval version of the Kiel Canal could be used for civilian or military transport from the Atlantic Ocean and the North Sea to the Baltic sea.
So it would certainly be possible for a fictional state in medieval Europe to construct canals to make transportation in an east-west direction faster, easier, and cheaper for commercial and/or military reasons.
Canal construction is usually beneficial to society, but construction of the Grand Canal of China was considered a heavy burden by the perhaps short sighted peasants and was one cause for the rebellions that overthrew the Sui Dynasty.
[Answer]
Sorry, but there is a first problem here: There is no such thing as 'limitless resources'. Even if two empires joined forces, they'd have to spend immense fortunes in this massive engineering job, which would be generational in terms of time.
Now, of course no emperor would dare to put a temporal limit to the future of its reign...and that is why he needs advisors, especially on the spending part. And the creation of this water network would divert uncountable numbers of precious manwork from military, farms, everything. And even if they wanted to use armies of slaves, they'd have to divert resources just to take them, move them, feed them and control them.
'Limitless resources' is akin to magic, not a realistic prospective. And the tragic irony is that, as technolgy advances, they'll discover that the canal idea wasn't really that necessary. Roads do just fine, they are cheaper to build, and can be adapted with time as the number and type of vehicles change, while a canal can offer only a limited space, it can accommodate only a few type of ships, and even less in case of draught, or the traffic could be blocked during a flash flood, while a wagon can leave the road and find shelter by a hostel built along the way. So, an empire should improve the *road* network. Romans created the best European empire around their roads. Sure, the Mediterranean Basin was a precious strategic waterway, but not so when you have to move inland inside the continent.
The reason Holland and Venice could realize their undisputed canal networks is that they are built on the right kind of ground. With a relatively lesser effort, they just had to let the water flow in the direction they needed rather than forcing it into a direction.
Without a heavy machinery industry to help them, your empire cannot do that job in a reasonable time and without draining all of its money.
[Answer]
An example of pre-industrial revolution canal is [Canal du Midi](https://en.wikipedia.org/wiki/Canal_du_Midi), a 240km canal finished in 1681.
It took around 15 years with 12k workers using pickaxes and shovels, so nothing new compared to what you would use in the late middle ages.
Estimated cost is around 20M livres. I could not find accurate numbers for this period, but [a 100 years later (in French)](https://www.lemonde.fr/idees/article/2011/08/13/le-long-passe-de-la-dette-publique_1559248_3232.html), crown revenues were around 500M a year, with national GDP at ~5/6B livres. GDP was apparently about 4B around 1700, so royal revenues around 300M sound reasonable.
Basically, such a project is expensive, but not stupidly expensive. As a comparison, France involvement in the American war of independence is estimated at around 1B livres.
As people said building the canal itself would not need anything too complicated: locks and lots of people.
However, if you have to crest an elevation to reach the other, then where the water comes from becomes an issue and you can't use the water of one to go into the other. You need to find a source near that summit with enough water to fill your canal in both directions. Or you need to bring that water from somewhere, e.g. using aqueducs. Romans could do it, but it's expensive/time consuming.
Lastly, I think you need to consider maintenance.
Canals tend to silt up really quickly because of the slow moving water, and the whole structure is much more exposed to things like frost, floods, draughts, ...
But nothing impossible if a centralised government puts its mind to it.
[Answer]
It can be done, it have been done, it's being done.
You're asking about Europe and you've read about Panama and Suez. What about, you know, Europe. Here, a map of water transportation in Europe, <http://fracademic.com/dic.nsf/frwiki/1471773> there are connections from Rotterdam to Constantinople, from France to Belarus. From Black sea to Baltic. From Baltic to White Sea.
There's a hill on your way? Too tiddly bad we don't care
[](https://i.stack.imgur.com/zrdHv.jpg)
You have place without water but you want to connect it to river?
Here, we have 48km long canal that connect Gliwice to Oder.
You want to transport that coal to Berlin? No problem, around 1605 they've build Finowkanal, THE OLDEST existing artificial water road. It connect Oder with Havel.
It can be done with shovels, a lot of workers and water gates. That's all. Just dig, build a gate, dig again, build another gate and you're done.
Do empires move people with this method? No, because it's too slow. It's good for moving stuff because you need two maybe three people for one barge and we know we send transportations in middle ages from Pinsk to Odessa that way. And with from Cracow to Kaunas through Vistula, Baltics Sea and Nemunas. People can move much faster than water and can traverse mountains in the shortest distance not the most optimal one as rivers do.
Feasibility of such empire - Roman Empire stretched from Britain through France, Spain, All Medditerean Basin and Black Sea through Armenia to Caspian Sea. There is no reason a smallish empire from Netherlands couldn't reach Belarus, Lithuania or even Moscow.
Prussia stretched from Netherlands to Konigsberg. So exactly to western Russia.
[Answer]
Humans can do a hell of a lot with pick and shovel, if they have enough time and resources so canals could pretty much be cut anywhere you like as long as you have good locks or other water retention technologies.
I would however suggest that canals are not altogether necessary. Have a look at how far the Vikings spread East and South; they often took their longboats over land using [portages](https://en.wikipedia.org/wiki/Portage) similar feats of overland boating were undertaken by the [Voyageurs](https://en.wikipedia.org/wiki/Voyageurs) on untamed rivers in the Americas. Building good roads that can be used to portage ships and cargo around obstructions both on and between river might be quicker and cheaper.
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[Question]
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In my story I'm creating, there are three sizes of dragons, from 6 to 20 feet long. The smaller ones create small coastal villages, and fish. These 6 foot dragons:
* are very dexterous and have developed hand like appendages at the end of their wings, so they can make small structures and use tools.
* Are not very wide, compared to their length, and probably weigh 90 to 110 lbs.
* Don't breathe fire, so no need to worry about that.
* Have strong talons to, if they needed to, catch fish that way. They are also skilled swimmers.
Could these dragons catch enough fish to feed themselves? Also, could they feed others if they can't? If they are as smart as humans, would a species of carnivores work together?
[Answer]
[The Wandering Albatross](https://en.m.wikipedia.org/wiki/Wandering_albatross) has a wingspan of 12 feet and lives solely on fish, so the diet is fine for your dragons.
If they also catch small fish in waist deep water, they could use their wings and work in small groups to easily force fish into nets. Their wings would help keep fish from escaping around them, effectively being solid walls maximizing the catch.
In lakes and oceans they wouldn't need boats. Working in groups with [nets](https://en.m.wikipedia.org/wiki/Fishing_net) attached to buoys, two or more dragons could fly out, drop the net in an arc and then dive in and out of the water chasing fish into the net. They fly back into the air grab the rope loops attached to the buoys and fly to shore dragging the net behind them. They'd probably take frequent breaks or work in multiple groups as this would be very hard work.
They could also get a long thin drag net, fly over a river or lake and drag it through the water behind them scooping up fish. Cast netting, drift netting and even a hand net to catch fish, simply by flying along and dropping the nets in the middle or in front of a school of fish.
With the proper use of nets, they'd have more than enough fish to survive and trade.
[Answer]
Not only do carnivores of the same species work together to hunt, but there are examples of carnivores of different species working together.
For example, wolf packs and human hunting clans working together is speculated to have led to the eventual evolution of dogs.
Dolphins and humans sometimes cooperate to fish in Lagunos, Brazil.
<https://www.livescience.com/20027-dolphins-work-fishermen.html>[1](https://www.livescience.com/20027-dolphins-work-fishermen.html)
And in Myanmar:
<https://www.nytimes.com/2017/08/31/world/asia/irrawaddy-dolphins-myanmar-fishing-conservation-cooperation.html>[2](https://www.nytimes.com/2017/08/31/world/asia/irrawaddy-dolphins-myanmar-fishing-conservation-cooperation.html)
An orca pod living near Eden, Australia, would herd baleen whales into Twofold Bay and alert the local whalers. The orcas would get the whale tongues and the whalers the rest of the whales. The Orca Old Tom, who died in 1930, was suspected of being over 90 years old.
<https://en.wikipedia.org/wiki/Killer_whales_of_Eden,_Australia>[3](https://en.wikipedia.org/wiki/Killer_whales_of_Eden,_Australia)
<https://en.wikipedia.org/wiki/Old_Tom_(killer_whale)>[4](https://en.wikipedia.org/wiki/Old_Tom_(killer_whale))
Thus your fishing dragons could be either competitors or partners of Human fishermen.
[Answer]
Dan covered would they eat fish quite well, so I will answer would they work together and feed others.
The answer to that is entirely up to you you will write their behavior, but there is no reason they could not, [vampire bats](https://academic.oup.com/beheco/article-abstract/28/2/565/2970156?redirectedFrom=fulltext) share food with relatives and even strangers and even keep track of food sharing favors and they are nothing compared to humans intellectually.
Social behavior is common in nearly every feeding behavior, herbivore, carnivores, omnivores, piscivores, even bulk feeders. As long as there is a benefit there is always a chance it will evolve. Piscivores(fish eaters) sometimes use group hunting to counteract schooling in fish, dolphins are well known for this, some help keep the schools from dispersing or fleeing while others feed, they do this just by swimming around it and harassing the school.
Even something as signalling the presence of a school can have huge benefits as there is far too much for a single animal to eat and the best place to store food you cannot eat is in someone else who will return the favor later. This can easily lead to more and more social interactions.
[Answer]
Would a species of carnivores work together? The Inuit live on hunting seals and fishing and they work together.
[Answer]
It would work if dragon would fine suitable cave near ocean(sea) and could swim. Also depends on kind of fish in ocean.
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