How can I have a permanent post-apocalyptic world?

Question

I've recently been looking into post-apocalyptic settings for a possible novel. I like the feel of people trying to survive off of the land with nothing but the clothes on their back, or banding together for survival in makeshift shelters, but there's always one problem: given enough time and resources, people will inevitably start to return to the lifestyle they had before the apocalypse. Cities will eventually be rebuilt, power restored, and so forth.

In order to keep the post-apocalyptic feel, I want to prevent that. An obvious way to do that is to have something in place actively keeping people from advancing, like zombies or a deadly virus, but even those can be defeated by a good enough wall, cold temperatures, or a cure.

Also, and this is very important, I don't want to change the world by introducing undead or the killer flu. I want the world to be as natural as reasonably possible. What I mean by that is if you were to walk outside in this post-apocalyptic world, you would ideally have to worry about nothing you wouldn't have to worry about if you went for a walk in the woods today. This also includes visual differences, like new animals or a changed atmosphere.

So here is my challenge: I want a post-apocalyptic world, permanently, with as little change to the natural world as possible. What the apocalypse was doesn't matter, as long as the following is achieved on a permanent basis:

• Daily struggle for survival, simply because people aren't used to living off the land.
• People limited to solitary, family based, or <200 people in a group. No big cities.
• Inability to maintain power, save for more archaic methods, like water and wind power. No nuclear. Batteries and the like are fine, but should be limited.
• Technology halted. No technological development, as everyone is trying to stay alive.
• No governing body, other than what individual groups appoint over themselves.

Obviously something is going to need to change in the world. My goal is to keep it as 'unpresent' as possible. Ideally, there would be a big apocalypse which would happen and then leave, but have permanent effects, without changing the natural world. Assume the world is present day Earth.

Answer 1

If you limit population everything else follows; specialists, and the technology they create and maintain, require the support of high density populations. There are several things going for you already:

• a post-apocalypse population crash, and there will be one, will effectively end the oil industry, more or less permanently, this sharply limits the yield of an acre of farmland to something closer to 1900s levels or less.

• the post crash population is also likely to be scattered as small random bands that will struggle to survive let alone grow beyond one generation if they cannot link together into larger groups with broader genetics.

• there are a number of ways to cause long term damage to the fertility of land, we've already degraded much of the best farmland in the world one way and another; as long as farm yields stay low population growth is restricted.

• there are also a number of ways to permanently damage the fertility of a population so that their growth rate is severely restricted, some of these are cultural, involving active infanticide, while others are due to genetic damage from exposure to chemical or biological agents.

• given a human generation or two large land predators could potentially breed back to the point where mankind finds itself on the menu in a way not seen for hundreds of thousands if not millions of years. This is partly because the post apocalypse population will lack certain skills and knowledge that were once common in humans, in particular how to hunt and survive outside of the village environment.

Any or a combination of the above could be used to realistically keep population flat across a wide area preventing a return to high density settlements and the technical advances that they make possible.

Do note that this can get a little hairy, the initial survivors have access to large reserves of pre-processed materials, refined metals, tools, bulk food reserves, synthetic cloth etc... that can carry them through beyond their actual population's ability to maintain and survive, when those resources run out they could be faced with a second lose of population as equipment that was "keeping their heads above water" breaks down.

Answer 2

Honestly, as long as the populations of the world is brought down to a small, SMALL percentage (even something as large as 1% could be fine), you should be okay. (I chose 1% because I believe that is the largest percent of a group that could survive for a true apocalypse, but that's just my personal view. I'll operate under this idea. You can modify it as you see fit.) We're at 7.6 billion. 1% of that would be 76 million people. Sounds like a lot, yeah? Well China's population would be about 13,860,000 or so of that. India's would be another 13,390,000 or so of that. That's already over a third of the remaining population in EXTREMELY large countries.

If we were being generous, that leaves the rest of the world with about 50 million people. Let's just assume all 50 million people SOMEHOW lived in the United States. (Not even Canada and Mexico, just the US.) That's 15% of the current US population. Mind you, this means the only places in the world with surviving human populations are USA, China, and India. Nowhere else in the world is there another survivor. Seems pretty unlikely that the population distribution would be so densely focused. So, let's spread this out a LITTLE more. If we were to include Canada and Mexico, this means North America's population just dropped to 10 percent of what it was. The last time the US Population was at 50 Million was in 1880 when the US was in the process of growing at an extremely fast rate. If we assume all other humans exist in only China, India, Mexico, and Canada (the latter two would likely try and move towards the US or the people of these nations would attempt to work together with the US to some extent), then that means there's not going to be an influx of immigrants. What the US has is what they have. If we assume the growth rate of the new America mirrors that of the world today (a 1.09% yearly population increase), then it would take about 175 years for the population to mirror that of the US today. It would take a little over 200 years for the population of the new America to mirror that of the combined US, Canada, and Mexico today. This is also assuming that America somehow managed to be practically unfazed by the apocalypse in comparison to the entire world, even compared to the only two other surviving regions.

In reality, assuming a 99% decrease in population, the US's population would drop to around 3,257,000. That's significantly less than the population of Los Angeles and less than half the population of New York City. Canada would drop to around 367,100. Mexico would drop to around 1,292,000.

What this means is if you go out to a mall or a crowded area, of the people that you would see now, only a handful of them at best would still be around. Odds are, everyone you know and trust will have died and you now have to survive on your own or with the help of strangers. Seems fine, right?

Well, as seen in the answer here, power would stop within a few months if you're lucky. In reality, it'd probably shut off in a few hours without someone manning the controls and keeping things regulated and even. As for the water, according to Life After People, a fictional apocalypse documentary, water would last maybe a few months. If you have a well and your own alternative source of power, you could get that to last longer, but that'd be rare exceptions for someone prepared for this. It would not be the norm. Internet would go out pretty quickly as it would not be a priority. Radio would last a long time due to a lot of stations having backup generators, but even then it'd go out sooner or later.

On the upside, you'd have your pick of housing. With 1% of the world's population left alive, this means, if we assume EVERY house had a mother, father, son, and daughter, then only 1 out of 25 houses would still have a singular resident. You really could take your pick of new abode. If we assume the deaths/disappearance/etc. of people was truly random, not taking into account age, health, and so forth, this also means that there is a good chance that the house you want could be someone too old, too young, too weak, or too sick to be able to defend the house. Odds are this wouldn't be how it actually worked out, but if we were going with raw probability of survivor, it works for the sake of thought.

Without the internet, most people wouldn't know what to do. There are three main things to consider when initially trying to survive and those are Food (and, by extension, Water), Clothing, and Shelter. Well, housing is readily available, so that won't be an issue. You can always raid the closets of the houses around you for clothing if you didn't have enough of your own. All that's left is food (and water). If you act fast, you could raid water jugs and bottles from stores, run them under the tap, and fill up enough water to last you a long time. A half gallon (really 64 ounces) of water is your daily recommended intake. You could probably get away with half of that (32 fl.oz. or a quarter of a gallon) if you want to conserve resources or a quarter of that (16 fl.oz. or about an eighth of a gallon) if you are relatively inactive and sedentary, maybe. Mayo Clinic actually recommends nearly double the usual 8 cups of 8 ounces a day, meaning while you may be able to get away with less, you probably shouldn't. Especially not if you're not eating appropriately. As the WebMD source says and the earlier Mayo Clinic confirms, about 20% of our fluid intake actually comes from other sources, namely food. This is the simple part. I'm pretty sure everyone knows to raid the pantries of nearby homes to gather food and drink. That's the easy part...

Then comes the hard part. Most people who lack experience in agriculture or military backgrounds will likely be unsure of how to start and maintain a thriving garden to live off of, let alone a farm. In fact, most people will likely see their storehouses of water and think they're fine where they are. Unless these people live near a source of clean freshwater, they shouldn't settle where they are already at. Even if they do live near a freshwater source, there's a chance it may not be clean enough to risk (especially in countries lacking in the same dumping regulations as the US.) This means anybody who isn't constantly moving towards cleaner sources of water is actively put at risk of dying from dehydration once their water runs out, sickness from the contaminated water, or dehydration caused by becoming sick thanks to the contaminated water. Once they get there, if there aren't people used to farming, fishing, or agriculture, they will quickly run out of food and you'll get raiders who are hungry and desperate stealing and killing for food. You may even wind up with worse atrocities like (essentially) slavery and other things depending on the morality of the survivors and how desperate they are for the things they want. You may get tribes of survivors starting to form together, but even then, it'd be a challenge. I honestly see dying out as a more likely scenario, at least in the US and Canada, either due to in-fighting, starvation, or lack of people to procreate with. In more rural countries, a new civilization COULD occur, if they can find other people, but again, they'd have to find people who are willing to cooperate and work together, sharing their skills and resources with others.

No matter what, within 10 years, you can expect petroleum products like gas to run out or be unusable, so don't expect people to fight over it... It won't matter. Honestly, it'd just be a day to day grind where humans inevitably die.

If animals and plants are affected by this too, then this will speed up the process for humans to die off. Insects and small animals will be able to resurge thanks to how fast plantlife regrows, but most larger animals will struggle as they fight over food. Wolf packs will have been disbanded and erased. Flocks of birds would be down to a couple members. Only patches of grass will survive. Most trees will have fallen. The world would regrow, but it would take a long time for animal life to make a comeback and humans will struggle to hunt and forage in this new world. You could expect this world to still be livable, but it's a matter of if humans will succeed. Once humans do manage to lay down roots again, though, expect there to be a resurgence in that respect too.

I'd say, post-apocalypse, 1% of the world (76,000,000) will remain. If I were to make a wild assumption, 1% of the survivors (760,000) will ultimately survive the post-apocalypse. Assuming a 1.09% growth rate (the current growth rate of the world population), humans would reach 1 billion in 663 years, the same approximate population of the world in 1800. Odds are, by this point humanity would be back to a similar way of life as in those days. Without regularly inducing apocalypse now-ish, you can't really expect the world the stay post-apocalyptic, especially if you don't want permanent environmental changes, which would happen no matter what form of apocalypse were to occur.

Basically, you're looking at turning the clock back on civilization by about a thousand years. It gets the job done once, but that doesn't assure it will work the second, third, or fourth times. With each event, humans will become more resilient and prepared, with bunkers already prepped and stocked for the next time and a larger emphasis on physical record-keeping which is likely what kept the humans from the first apocalypse alive: those who were smart enough to hit the library.

Answer 3

They would be very hard pressed to advance if all the best resources were gone.

Maybe a lot of people evacuated the planet (or tried to) before the apocalypse, taking with them huge colony ships full of a lot of the best that the planet had to offer. All the gold in the vaults is gone. All the processed steel is either gone or what's left is all collected together in one spot that the survivors don't realize. They took with them as much food, medicine, and everything else that they could. Some people got left behind in the now-resource-less world.

Or maybe the planet is just not rich in good resources to begin with. No iron. Copper is even more rare than it is here. The planet has no areas of rich and abundant life; only enough to survive.

If they cannot make durable tools, they get no rest. Stone tools need to be replaced often. And if there are not a lot of trees, and if the land cannot support a lot of trees, then they need to be conservative in their wood usage as well. About the only thing they are likely to have a lot of are rocks. That would force a hard life.

What scarce little they could get which is better would be very highly prized. If someone did manage to make an iron tool, it would be a priceless heirloom, an artifact carefully guarded. Even just a nice steel knife or an ax would be worth fighting tribe-scale battles over just because of how much better it would make your life.

Answer 4

A maternalistic AI has taken over, and is convinced that technology and cities are bad for us

I know it's a bit farfetched, but if Skynet rained fiery death down from satellite weapons on any communities that were too large or advanced, that would maintain your desired conditions.

Textbooks and books in general are currently super common, and there's enough general technical knowledge diffused over most modern countries for a return to the dark ages to be as sustainable as humanity's previous forays in that direction, unless you have an active agent discouraging the success of would-be rebuilders. Sorry.

Maybe, given a few more generations, print books will be sufficiently rare, and electronics sufficiently complicated, that we couldn't just revert to nineteenth century tech and work back up, given some sort of collapse. I'm not persuaded that we're there yet.

Answer 5

You can't stop civilization without a persistent attack that permeates the natural world. In other words, your ideal of "if you were to walk outside ... you wouldn't have to worry about [anything different than] if you went for a walk in the woods today" is fundamentally impossible. Our civilization today, though radically different than that only 200 years ago, wasn't born of a vacuum. It came from a civilized history going back at least 5 millennia. They had no technology as we think of the term today, yet managed to build cities, trade routes, and complex economies, and they lived in virtually exactly the same world we have today. Therefore, your world necessarily must include something different that is currently not there. Disease, zombies, robots, aliens, etc are all easy plot devices, so I can see your reluctance to use them.

You can change humans instead. Consider Planet of the Apes. In that story, humanity is radically altered such that they become too simple to build a civilization. A remnant of unaltered humans would be the focus of the story. This is like zombies in some way, and you're also left with the question on what to do with these new humans (make them violent, slaves, etc.). Again, the threat has to be persistent to keep civilization down, so writers revert to the disease and zombie tropes.

Since you want to specifically avoid those tropes if possible, consider an American TV series called Revolution that handled this very well, though you might view it as breaking your "natural as possible" rule. In this post-apocalyptic world, electricity generation and transmission suddenly becomes impossible. Literally, moving a conductor through a magnetic field no longer generates electricity; it does nothing except waste your time. There's an early scene of a character explaining how it's as if the laws of physics suddenly changed. It's later strongly hinted that it's actively caused by some kind of runaway nanite technology, so there is no need to convince readers of a change in fundamental physical laws.

Something like this should work nicely. You could handwave some other mechanism like a solar flare or space radiation wave so you appear more original. You could even use this exactly, because though the show was critically acclaimed, it did not have a high viewership, so your story likely won't be seen as a ripoff.

The major caveat is that your story can now no longer use boons from the pre-apocalypse that depend on this physical law. Technology, as modernly understood to be electrical devices, would not only halt but be virtually non-existent. Any meaningful advances would be strictly in the mechanical sense, which given decades, centuries, or millennia, can leave you with a very creative outlet. And see we're back to the same problem. This is a persistent change, unnoticeable on a walk in the woods, but it's not believable that civilization could not rebuild to 19 century levels in one hundred years or less.

I've tried to offer something conceptually different, but bear in mind that ultimately civilization cannot be stopped without changing the world or humans in a fundamental way.

Answer 6

The Iron Wind

Borrowed from Numenera, the Iron Wind is a "storm" of nanotechnology that wanders the world, wiping out most everything in its path.

To work for you (and to avoid a direct copy-pasta), it would likely need some tweaking. Maybe it is attracted to certain forms of EM radiation, preferentially destroying those communities that try to establish wireless communication. This serves to keep civilization nomadic (in order to avoid the storm when it wanders by by chance) and communication between groups sporadic (due to having no means of communication faster than the fastest vehicle, complicated by non-stationary communities), limiting the amount of cooperation possible and thus stunting technological advance. Perhaps there are dozens or hundreds of smaller swarms, making them a less overwhelming, but correspondingly more common, threat. Perhaps they are some other technological boogeyman gone awry - killer robots, satellite based lasers, some bio-engineered virus - whatever.

When the "storm" is not present, the world is largely as one would expect - rotting infrastructure and largely primitive humans eking out an existence among them. By tweaking how the menace behaves, you can block other specific technologies if desired. In the presented scenario, there is nothing stopping a group from developing any level of technology desired so long as they avoid certain forms of EM radiation. If you don't want that to happen, have the threat be attracted by other signs of civilization as well.

Where did it come from?

It doesn't matter, really. A weapon gone out of control, some alien punishment ("A Wind Named Amnesia" anyone?), or the wrath of God. It can play a major part of your world or just be a Deus Ex Machina.

Plan B

Radiation. It's been a staple of post-apoc literature for decades for a reason.

A global nuclear disaster irradiated much of the planet. Side effects of radiation - acid rain, irradiated oceans, etc, make life difficult in the rest of the world. A decent breeze can move irradiated particles hundreds of miles, making no place permanently safe. And so people are nomadic (again), and acquisition of resources id severely limited because all the good stuff is surrounded by kilometers of radiation (because it just so happens that people tend to live around the resource richest areas, and population centers are a preferred target for those with nuclear weapons).

And because much of this radiation has a long half-life, it won't decay to safe levels for thousands of years, and so this problem doesn't go away any time soon, probably outliving humanity, considering its sad state of affairs.

Answer 7

To reframe your question a bit: What is the fundamental prerequisite condition for civilization as we know it?

There's at least a couple good candidates for answers here, but the one I think will be most immediately useful to your purposes is:

There must be a surplus of food such that some people can do something significant with their lives other than just trying to keep themselves fed.

The inversion that solves your problem: There must be something preventing that.

You've got a wide variety of choices here. Points of failure include nitrogen fixation, pollinators, salinity, acidity, too hot, too cold -- and that's just on the supply side. To break the demand side, speed up everyone's metabolisms or cripple their digestive systems or something like that.

I think this is enough to get you pointed in the right direction.

Answer 8

Other humans.

You could simply state, that whenever a certain amount of ressources was accumulated (which is necessary for building a city / civilisation) raiders showed up, killed most of the people and stole their stuff. For that reason people at some time stopped trying to reach that goal. It may have become part of their mythology that too much wealth attracts monsters (the raiders) and for that reason the tribes would be too afraid to take any action in that direction.

It might even go so far, that whenever a certain level of population is reached, some members get expelled in order to not attract the evil beasts attention.

Or the apocalypse was caused by some new technology and therefore science itself is viewed as some terrible evil that is to be persecuted. A Mythology like that would keep a society at a very basic level for an unlimited period of time.

Answer 9

I don't think you have to do anything here. You have a world in which all extraction industries are basically gone. It's a world of trying to subsist on salvage and recycling--and it's basically doomed to run down, not rebuild. Your problem isn't recovery, it's keeping it from running down.

Answer 10

For some reason, for example a virus that becomes more lethal the more nerve connections you have (ie the smarter you are), all the smart people are gone. This virus could also have changed the surviving worldwide human DNA so that long-term planning is hampered.

Possibly viruses were created for warfare purposes that are designed to infect people and only activate to murder status when a minimum amount of nearby people is reached. This means that communities that rise above a certain size immediately get killed off. Anyone who witnessed the ghosttown would likely believe it an act of God punishing those people for their practices, and people will keep smaller communities and avoid specialized and sinful tasks that appear inside larger communities.

Otherwise religious practices could heavily hamper research as has been done in the past. Gods plan is to be followed, not messed with by trying to change things with medicine or technology the gods hadnt offered.

Answer 11

1. Permanent: Nothing is permanent which is a bit of a problem but not insurmountable. We can go with "long enough".
2. Post apocalyptic: Itself theoretically a temporary situation. The principle being that you're living day to day on the salvage of the pre-apocalyptic civiliation. There's a point where the salvage runs out (or is no longer accessible to your primitive groups) and your post-apocalyptic scenario becomes merely a primitive hunter-gather scenario. We have to somehow maintain a steady supply of salvage. We also need to keep these people on the move and prevent them from becoming a settled farming community or migratory herders. This is actually the hardest part.

We have a problem here. Consider Chernobyl. The nuclear fallout made the area uninhabitable to humans for decades. This in turn allowed a surge in wildlife populations and diversity. It turns out that the presence of humans in an area is far worse for nature than the fallout from a nuclear reactor going pop. Nuclear war isn't going to cut it for this one.

A far better bet is an ice age. Highly unlikely in the current scheme of global warming based climate change, but it has effects long enough to be permanent on human scales and would utterly devastate current civilisation. Glaciers would put out a steady stream of salvage during a summer melt, regulating the rate at which it resources could be recovered and allowing a prolonged culture of living on the salvage of the old world. You wouldn't be able to hang around the edges of the glaciers for long though, so it's only a summer trip up for salvage and then a return to warmer climes for winter.

This migration along with the fact that an ice age also causes much of the world to dry up, limiting the effectiveness of a static farming lifestyle keeps what little population can now be supported fairly mobile. Hunting, gathering and salvaging.

Much of technological growth is population density dependent. With a very low population capable of living a hunter-gatherer lifestyle its unlikely you'll have any noticeable technological recovery or development for several generations after any massive crash.

However this approach will tend to leave a slightly environment to a modern person, being much drier, coastlines will be unfamiliar due to the aforementioned drying (sea levels were 120m lower during the last ice age) and different vegetation will exist in previously familiar climes.

The tickboxes

• Daily struggle for survival, simply because people aren't used to living off the land.

This can only last a decade or so, at most a generation, because after that people will once again be used to living off the land. The daily struggle to survive after that is your day to day struggle to survive. Can we eat? It is safe to sleep here?

• People limited to solitary, family based, or <200 people in a group. No big cities.

Hunter-gather society is fundamentally limited to small groups, nothing to worry about here

• Inability to maintain power, save for more archaic methods, like water and wind power. No nuclear. Batteries and the like are fine, but should be limited.

Since there's minimal need, there's minimal drive to develop these things until people are trying to settle down. Expect crude waterwheels at best.

• Technology halted. No technological development, as everyone is trying to stay alive.

Again, this is a function of population density outside isolated cases. With small groups there's going to be minimal transmission of ideas and no drive to industrialise.

• No governing body, other than what individual groups appoint over themselves.

Population density again. If you kill off enough of the population there's no room for governments.

Answer 12

The world has no metal.

This world's crust is very poor in easily worked structural metals -- iron and copper, at least. Some metal artefacts may remain, having been imported before the collapse, but it's in little bits. This doesn't prevent cities -- IIRC the Inca and Mayan civilizations had no metal except gold jewelry -- but it limits the tech considerably.

Also, people don't know how to do basic tech because they're so used to high tech. Knowing how to make things with 3D printers doesn't help much when you have to make them with sticks, stones, and leather. This could also eliminate agriculture, large buildings, and maybe even wheels.

The condition "people aren't used to living off the land" doesn't work. No matter what conditions are, people will get used to them, and probably in a few years.

Answer 13

You change the laws of nature so that electricity and internal combustion engines simply don't work any more. See S.M. Stirling's "Emberverse" series.

Your "Daily struggle for survival, simply because people aren't used to living off the land" isn't really a factor, because those who don't know how to live off the land (or force others to do the work for them), or have land nearby to live off (urbanites, IOW), die off in quite short order.

Answer 14

Extreme cold. Efforts required to survive in -50 Celsius would be nearly prohibitive for agriculture, mining, etc. Especially on large scale. "Ice age" world would be challenging even in regards to basic necessities like water. Limited availability of fresh water have a great potential to cripple civilisation as we know it.

Highest/Average temperature can be tuned for desirable effect. Lower temperatures would reduce habitable zones - a little research might be needed to guess/adjust the tunables...

Depleted fossil fuels would be another option...

Answer 15

The earth takes a glancing blow from a large object, not enough for total extinction but enough to knock us back to the stone age.

The impact also throws the earth's orbit out into a more elliptical shape, causing large seasonal fluctuations.

Just as people are adapting to that it turns out that the object is still out there having shattered into fragments after the impact, and the earth passes through the cloud every X years causing meteors to rain from the sky shattering any civilization that has started to rebuild.

A single event but with long term and recurring consequences where you can tweak the numbers enough to keep some people alive but make it very hard to build any sort of lasting civilization.

Eventually we'd either die out or rebuild but it would take a long time under those sort of circumstances.

Answer 16

Armageddon, Jehovah's Witness style.

This image of Paradise Earth from Watchtower 1975 is interesting for many reasons. https://www.jwfacts.com/watchtower/earth-forever.php

The Jehovahs Witnesses have very specific ideas about what will happen with Armageddon. As I understand it, 144,000 individuals will be chosen to inhabit Earth, remade as a paradise. These 144,000 will return from the dead.

https://www.jw.org/en/publications/books/bible-teach/what-is-gods-kingdom/

Who are those 144,000? John himself tells us: “These are the ones who keep following the Lamb no matter where he goes. These were bought from among mankind as firstfruits to God and to the Lamb.” (Revelation 14:1, 4) Yes, they are faithful followers of Jesus Christ specially chosen to rule in heaven with him. After being raised out of death to heavenly life, “they are to rule as kings over the earth” along with Jesus.

As opposed to leaving the Earth and going to a different plane, the Earth itself is remade as a paradisial home for these 144,000.

21 After Armageddon, mankind will be under just one government, God’s Kingdom. That Kingdom will do God’s will and bring wonderful blessings. For example, it will remove Satan and his demons. (Revelation 20:1-3) The power of Jesus’ sacrifice will be applied so that faithful humans will no longer get sick and die. Instead, under Kingdom rule they will be able to live forever. (Read Revelation 22:1-3.) The earth will be made into a paradise. Thus the Kingdom will cause God’s will to be done on earth and will sanctify God’s name. What does this mean? It means that eventually under God’s Kingdom everyone alive will honor Jehovah’s name.

Thinking about waking up in this world:

• There are not many humans for an entire planet.

• By the racial diversity, it looks like the 144,000 are gathered together from different places in the earth - this is a recurring theme in the images I saw. Also, if these people have been dead, some might have been dead for a long time. They might have lived and died a long time ago. The 144,000 might struggle to communicate with each other.

• It is Earth, renovated. It can be as close to the original as you think it is appropriate, but there will be differences. You will note the lion, recognizably a lion with its carnivore canines, preparing to eat a handful of grass. Things like that suggest this remake of Creation was done in a hurry, or possibly by entities that were caught by surprise with the task, or who did not really comprehend the complexity of the original and how the remade whole might function going forward.

• People will live forever. I am not sure, though, this means that they are invulnerable to harm. These individuals died once. Maybe they can die but they come back?

---

Overall, this vision of a post-apocalyptic paradisial Earth is super interesting and one can find lots of detail about it from the Witness point of view. I like the idea of Earth stripped of almost everyone and intentionally made as nice as possible for the deathless humans set to inhabit it. But it is not so nice that everyone lives in mansions - in the image there is a man, wearing a shirt from a factory, drinking from a stream with a saucepan. I like the idea that this remake is carried out by well-intentioned entities that don't really understand what biological things (including humans) do on a day to day basis to survive. There may be other gaps in their understanding which will become evident as time passes.

Answer 17

A state-developed nano-tech research program is nearing completion when a cold war starts escalating between several highly developed nations. One of the researchers finds out that upon completion the nanomachines will be networked with the existing spy satellite network and turned loose as a first strike weapon to bring the entire world under the control of the government. Horrified about the dystopian future this would bring about, the researcher, who is a bit of an anarchist and an environmental activist, hacks together a software patch and changes the directives of the nanomachines in an attempt to forever eliminate the threat of government tyranny and prevent mankind from destroying the environment.

When the government released the nanomachines the hijacked directives were something along the lines of:

1. Any community with more than say 200 people would get a daily warning to reduce its size to under 200 or have 1% of its population randomly dissolved.

2. Any communication or network device developed to link communities would be immediately dissolved.

3. The leaders of any community regardless of size that didn't employ a 1 vote per person democracy would be dissolved.

4. Any machine that uses petroleum as a fuel would be rendered inoperable.

5. Any nuclear-powered device or weapon would be dissolved.

This, of course, would destroy any government, police force, or army on the planet, resulting in a mass exodus of all major cities, rioting looting, starvation, and general apocalypse.

Once the human population on the planet had balkanized into ragtag isolated clans there would be essentially no evidence of the nanobots as they would be too small to see and would no longer be performing visible actions. Of course, if any of the groups combined or grew larger than 200, or started developing communications equipment or petroleum-fueled machines the nano-machines would again take action.

If after a couple of decades the controlling satellite network were to fail or the population of the nano-machines was to fall below a critical level it would no longer matter as it will have long been taboo to ever have a clan with over 200 people or to tinker with advancing technology.

Answer 18

Monsters.

The earth is covered by a huge number vicious beasts. They are normally territorial and can generally be avoided, but they are strongly attracted to noise - so any sort of industrialisation, or even the clamor of a large number of people living together, will attract beasts from all over to attack them.

You said you wanted it to appear to be the same, no new animals - well, this is impossible; in a post-apocalyptic setting, without humans to hunt them, there will be a massive resurgence of wild animals. So it's going to be different regardless, the only question is how different.

You can still make it largely appear the same, though, if the monsters are hard to find and ignore individuals not making too much noise. Maybe they hibernate underground, so you can walk through the woods and it will appear not different from the woods today, but as soon as you turn on your car engine: Bam! They burst out of the ground and eat you!

This has the bonus of allowing the new monsters to eat the wild animals. Currently, wandering wolf packs are rare encounters because humans killed them all. In this world, they are rare encounters because the monsters eat them. Thus the world looks the same, just... postapocalyptic.

As a result, humans can only form small communities. Only surface Mining is possible - oil drilling is certainly right out. Shelters will have to be makeshift - too much hammering might attract the monsters. The focus of humanity will shift to a heavy emphasis on hunters/warriors, to protect the villages. Technological advancement will be impossible, with life a daily struggle for survival.

Answer 19

For a good example see S. M. Sterling's series that started with "Dies the Fire"

See https://en.wikipedia.org/wiki/The_Emberverse_series In it electricity stops working, as well as anything using more than about 100 psi.

People are more efficient in larger groups. 200 is a bad size. Hunter gatherers are extended families -- 20-30 people maybe. As soon as you have any form of agriculture, towns of a thousand are quite possible. Examples are in the Iroquois Federation, the Cherokee, and the Mississippi mound builders in north America. The Aztec and Maya in central America, and the Inca and the raft of smaller nations they conquered in South America.

One way to keep the tech down is to not have agriculture. Make a climate that is more variable. (We may be doing this already) If agriculture fails, then famine takes out 90% of the people, and the remaining ones don't have the ability to restore the technology.

Comment asked 'how variable?'

• India had massive crop failures when the monsoon failed one year.
• The first 3 colonies in California died of thirst and starvation.
• Lot of the mass migrations in history have been due to short term climate shifts that made the previous system of agriculture unworkable.
• Agriculture right now is very technologically dependent in many regions.

Right now we are getting some extremes due to arctic warming. This lowers the temperature differential between pole and equator, which in turn makes the jet streams weaker. They wander more, and move much more slowly. A standing Rossby Wave last winter causes western North America to be much warmer than normal, while eastern North America shivered.

Right now California seems to be running several years of drought followed by lots of rain. Without dams, pumps etc how much of the San Joaquin valley would support a farmer.

Coming up with a plausible change that makes ALL agriculture impossible is hard. But getting it to fail in 90% of the world I bet only requires tripling the standard deviation of the rainfall per year.

You would have pockets -- Oregon's Willamette Valley, say, or the Skagit Valley north of Seattle -- where ag might still be possible. But the pockets would b small, wouldn't connect, and would devolve to 1700's technology. Best you could hope for would be wood fired steam + sailboats.

If you want a more extreme case, have aliens move the moon to half the distance from the earth, and incline it's orbit more. This would speed up orbital precession by a bunch, increase tides by a factor of 8, make them much harder to predict, trigger a whole bunch of earthquakes and volcanoes.

Answer 20

Humans as cockroaches

Most existing answers that suggest a population drop or resource depletion suffer from the same flaw: With time, humans will adapt. With stone age technology, they were able to populate the entire planet, including scorching deserts and frozen tundras. That was with a primitive understanding of physics and no technological force multipliers. It's almost impossible to roll humanity back to stone age, and even if it were, it'd simply be a matter of a few hundred years for humans to rebound (recall that previously domesticated animals and food crops have been spread across the globe and will not have to be "redone")

The only way to prevent humans from rebouding is by kicking them from the top of the food chain, so to speak. Imagine AIs rule the Earth. It's not like they're going out of their way to exterminate all humans, they simply don't care whether we live or die, anymore than we care about trees, grass or ants when going around doing our business. Most of the Earth will be taken up by their infrastructure, and humans will be able to survive only on the fringes or as thieves and parasites, a pest to be occasionally managed. Some AIs might have security measures to keep humans out of vital bits of infrastructure. Humans are quite smart so they'll probably find a way to eke out a living somehow. Just not in the billions, and not with huge settled cities, but as nests and bands.

Answer 21

Imagine its not quite present day earth, but the near future and nearly every piece of technology we use is digital. For example, +95% of cars, boats, airplanes, etc are now self-driving. All police and military have fingerprint locks on their firearms. All schools have transitioned textbooks to digital media. Then it happens a super solar flare wipes out all electrical infrastructure and devices on the planet.

With no vehicles transporting food and no water pumping to houses, the major cities would quickly fall into anarchy. Without access to their weapons, the military, police, and government officials that actually stuck around in major cities and tried to govern would be overrun by the mob. After the initial die off the survivors would have to learn how to live off the land from scratch and would largely fail. Only a handful of isolated survivors would live to create the next generation and most personal knowledge on how any advanced technology works would be lost.

Basically, the technology would be too advanced for people to look at and figure out, all records on how things work would be gone. Heck, there wouldn't even be an oral tradition passing on basic skills. In two generations the vast majority of the planet would probably not even be able to read. The tech level would be set in some ways lower than it was in the dark ages... at least they knew how to farm and create simple tools and shelters then.

Strangers would be largely unwelcome as different groups would take to raiding other groups to survive so it would take probably generations before people started banding together again. Even large raiding groups wouldn't work as there would only be so many nearby groups to prey upon and they would eventually turn on each other.

In short, it could take several decades before cities start to rebuild and even when they do it would probably look closer to a medieval serfdom than a modern city.