I'm working on a post-apocalyptic world for a game and the more I think about it the more unsure I get about the technological development of the setting being believable.

So I'm asking how likely a certain level of technological regression would be given the following assumptions:

In a world that experiences a long lasting dramatic global cooling (a series of impact winters caused by a shower of asteroids that impact the earth over time for example, or maybe a volcanic winter?) for more than a century, reducing humanity to a population of maybe 2 million globally. How much technological regression would be plausible in this case? Assume that most technology that is in use by then has become complex enough that simply copying them cannot be done (requiring advanced electronic manufacturing and such).

  • Would it be plausible if the knowledge of electricity is reduced so that it becomes impractical?
  • Would it be plausible if the knowledge of chemistry was lost to such a degree that only the most useful and easiest to do formulas would be remembered?
  • Would it be plausible if knowledge of manufacturing strategies were reduced to such a degree that humans would be stuck with artisanal production for a long time after?

Would it also be plausible if recovery was slow, in the level of several centuries, after such an apocalyse?

In such an apocalypse, global trade networks would collapse quickly I would assume (especially if there are armed conflicts between groups of survivors for the little fertile land that is still there during the long winter) I would assume and a lot of technology would be impractical for a long time in the future as requried materials would be very hard to get and might even be hard to salvage from the ruins of the old world in sufficient quantities. Though some of it would be possible I'm sure. Power sources would be limited, wind power might still be doable in the small communities that would survive but would it have enough practical uses to preserve for such a community? I would assume that most fuels would be impractical for such a community, with easily accessible oil and coal deposits already being depleted. So I guess easy portable electric power would be out of the question. Likewise, I also assume that the vast majority of people will be forced to do tasks that are required for basic survival, whether they work in Agriculture or other basic resource gathering operations.

Furthermore I would guess precision machining would not be doable without access to already complex machinery, limiting how complex any mechanical machines would be. But I'm unsure how fast these capabilities would be to reacquire. Finally, even if the old society had mostly phased out text books in favor of digital media would the surviving text books still around be enough to rapidly have society regain the lost knowledge to a level where they can make practical use of it?

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    $\begingroup$ Two million people in the entire world? That's a level of population last seen in the Palaeolithic period. Population density would be about 0.05 persons per square kilometer in densely populated areas! $\endgroup$ – AlexP Jun 19 '18 at 12:10
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    $\begingroup$ I will also (once again) point out that The Survivor Library is a thing. There are people who download it and print it out, other people who keep copies on laptops inside faraday cages, and so on. We'll (probably) be just fine in the long term. $\endgroup$ – Draco18s Jun 19 '18 at 22:54

10 Answers 10


There are minimum population densities that you need to maintain in order to have a given degree of specialisation and division of labour. If the population is broken down into single families trying to scrape a living in hostile conditions then they don't have the time to maintain the equipment they have let alone manufacture new so in terms of material culture they'll revert. Over the short-term, for maybe three generations, there will still be a practical knowledge of a lot of technology that there isn't the labour to maintain in physical equipment. After those skills die out there may still be printed records available for some time to come, these will largely form a basis for experimentation rather than a ground up how to guide in most cases because they're too technical for someone without a grounding in the basic operations.

In short if population densities remain extremely low for extended periods, like two-to-three hundred years you could theoretically push people back to stone age farming. In reality I think there are two barriers to that:

  1. It would take a severe drop in average fertility to keep people down in numbers and population density long enough for all the people with skills and knowledge to die out.
  2. We use too much metal in the modern world; after most of the population is dead a modern city becomes a huge mine for refined metals. Even if you have to break rebar out of K-rails with rocks it's still far easier that mining and smelting ore. Given the huge volumes of metal in modern buildings I'd expect something like the late iron age to be as far back as you could go near existing settlements, even reasonably small ones.
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    $\begingroup$ This point is often underestimated: in order to have technology, you need to have a society with enough surplus that some people can work on it. Otherwise, even is knowledge is still around, if everyone has to work 12 hours per day in order to not starve, no-one will have time to re-develop electricity. $\endgroup$ – Eth Jun 19 '18 at 16:49
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    $\begingroup$ Another factor, surprisingly, is light. The ability to read and be otherwise active at any hour of the night is an enormous boost to productivity, especially intellectual or technological one. Before gas and electric lights, people relied on weak, expensive (and smelly) candles that took resources and a long time to manufacture. And before that, it was only the very low-quality, extremely fuel-hungry light of fires. $\endgroup$ – Eth Jun 19 '18 at 16:52
  • $\begingroup$ Agreed on the population density prerequisite for technology, which is part of the reason I'm not sure the above scenario would even be likely to support an Iron Age civilisation. The Bronze Age was less characterised by the use of bronze in tools and more by the development of the first proper civilisations. If you don't have the population to support that, what you get is a pre-bronze age culture that just happens to have access to metal tools. If you want an example of a large pre-bronze age settlement then this is good: en.wikipedia.org/wiki/Cucuteni%E2%80%93Trypillia_culture $\endgroup$ – Ynneadwraith Jun 20 '18 at 9:24
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    $\begingroup$ @Ynneadwraith Yeah fair enough my major point was that with so much metal already refined and lying around for the taking you don't need to have the usual prerequisites so it presents a limit on how far material culture could slip. But you're right that the overall sophistication of a civilisation and the nature of its material culture don't have to go hand-in-hand. $\endgroup$ – Ash Jun 20 '18 at 12:29
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    $\begingroup$ This answer sort of going into the understanding I had before. I might go mostly with what I have as it matches this answer, the people of the world having been very small in number and highly isolated from others outside their region until just a few generations ago. When technology is coming back, its mainly the ones that are most immediately useful and less demanding of infrastructure, but the old knowledge being possible to find will help rapid advancement in the future. Though the other answers have made me rethink certain technologies! $\endgroup$ – OnePie Jun 20 '18 at 17:26

Would it be plausible if the knowledge of electricity is reduced so that it becomes impractical?

Not really. Electricity, it's uses, and it's conveniences are widely known and taught. Many, many toy stores have electricity learning kits. Every science museum in the world has displays and hand-on learning tools. Most schools in the world teach about it. You may not recall the details, but a trip through your memory will lead you back to that museum or that toy store, and the raw materials and techniques to re-learn.

Would it be plausible if the knowledge of chemistry was lost to such a degree that only the most useful and easiest to do formulas would be remembered?

Chemistry would certainly not vanish. Just knowing the fact that there are formulas (and elements) skips thousands of years of slack-jawed guessing. My dining room has a place mat with the periodic table. One of my teenage kids has a T-shirt with the periodic table printed on it, and (out of earshot of her peers) will sullenly admit to fully understanding most common chemical concepts. Those toy stores and museums have chemistry learning tools, too.

Would it be plausible if knowledge of manufacturing strategies were reduced to such a degree that humans would be stuck with artisanal production for a long time after?

Well, that doesn't kick us back very far at all. Modern industrial mass production is only a tiddle over 100 years old, and many current methods (CNC, robot-assist) are barely one generation old. There's nothing magic about them - most are simply incremental improvements that can be quickly re-learned when required.

  • $\begingroup$ Just the shear number of electric motors and generators in the world make it difficult to imagine how people could not generate electricity, even a basic current. $\endgroup$ – Keith Morrison Jun 19 '18 at 6:24

There is no amount of physical destruction (books, tech, etc) that will solve the problem because an absolute boatload of knowledge is in people's heads. 99%1 of today's technology was created in the last 150 years. This strongly suggests that, if all the books and toys were taken away, it would be recreated in no more than 150 years and probably a whole lot less. In my opinion, believably within a single person's lifetime.

Not to be too sarcastic, but necessity breeds (re)invention, and what's more necessary than snapchat? Am I right, or am I right? 😀

That means you need to get rid of more than the books and the toys (because any toy left behind is a massive clue. Reverse engineering isn't as hard as people think.), you need to get rid of people or force people to not use what they know.

Option A: You get rid of the right people. This is (for example) a highly selective virus that only infects people above a certain IQ, or that have a specific knowledge base, etc. But, this is the most unbelievable scenario I can think of.

Option B: You get rid of everyone above an age that could possibly replicate technology. This is much more than the people who actually know how to do something, you need to get rid of people who remember that something can be done. Remembering that you can use a rounded-piece-of-glass reinvents the field of optics a whole lot quicker than not knowing about glass at all. Killing everyone above 13 might do it. Killing everyone above 6 would do it — but you just put the entire population at unbelievable risk because 6-year-olds have a bit of trouble taking care of themselves.

Option C: Something (usually war) gets in the way of re-development. This means the knowledge is there and even appears in pockets, but the full re-development is nearly impossible due to an external force that prohibits that development. The chaos of war is the only thing I can think of that would do that. But this doesn't solve your problem. Today's knowledge is still in people's heads. Give the right dude in the back woods someplace with reasonable resources (like nearby hardware/feed stores that have animal antibiotics and fertilizer), most of modern chemistry could be recreated in a few years. Most of all modern tech could be recreated very quickly as peace (and the communication that comes with it) is re-established, and warlords would begin to realize the value of their wizardsscientists very quickly. Therefore, I don't see this option as helpful to you.

Option D:—A virus or magic death ray that wipes out memories. Even if you had all the books and toys, if you can't remember how to read, how to speak, etc., then you really are pushed back to the stone age and the presence of all the knowledge and technology around you can't help you.

Option D is obvioiusly my favorite choice. We get a lot of people on this site who ask along the lines of "my post-apocalypse society has been pushed back to the stone age and here's my question?" Except that there's rarely a serious explanation of how they got pushed back. The people who ask that question don't understand the considerable depth of understanding that comes from just using the technology of today. Really, if you were a 10-year-old who grew up with a yard with a sprinkling system, how hard would it be to realize irrigation would help you grow crops?

Therefore, from my point of view (and to answer your question), it's all or nothing. You either push people back a few decades, or you push them all the way back to the stone age. There's nothing in between.

1Metaphorically. I don't know the actual percentage and don't believe it matters.

  • $\begingroup$ "What's more necessary than snap chat?" sorry to disagree but memes! and adult websites $\endgroup$ – Blade Wraith Jun 19 '18 at 9:45
  • $\begingroup$ Option C may be very unlikely with such low population densities, the competition for natural resources would be nearly nonexistent $\endgroup$ – Nosajimiki Jan 17 at 22:21
  • $\begingroup$ @Nosajimiki, you're probably correct, but humans are funny that way. To quote satire from an advert for the game Team Fortress 2, "'Cause at the end of the day, 'long as there's two people left on the planet, someone is gonna want someone dead." I've seen children steal food from a friend's plate despite theirs being full. Yup, funny that way. $\endgroup$ – JBH Jan 17 at 22:32
  • $\begingroup$ The technology developed in the last 150 years was made possible by the infrastructure developed and built in the last 10000 years. If everything was destroyed, you would have to start from somewhere. Even though people would retain much of the knowledge, if they spend the next several decades just trying to survive, they may never get around to teaching such knowledge to their children. If they do not immediately start redeveloping civilization, in 2-3 generations much of the knowledge would be lost. Books would remain, but that would rely that the children would be literate, $\endgroup$ – Sonvar Jan 18 at 3:51

We can do a lot, with a few people, if we WANT to

If you haven't done so already, read at least the first novel of the 1632 series. Basically, 3,000 people from a small town in West Virginia in 2000 get transplanted to 1632 Germany. The key points I see relevant to this discussion are:

  1. Knowledge is the most important thing.

  2. Even if computers become useless (they won't, by and large, last 100 years, and producing new computers won't be easy), books will last a long time. While we rely on the internet for "everything", there is plenty to be found in printed books. Printing more books to distribute knowledge doesn't require 21st century technology or mass production from factories in China.

  3. If the surviving people want to accomplish a lot, they will.

That's not to say it will be easy. If all major factories, large electricity generation plants, etc. are destroyed and people have to live off the residue of modern civilization for 100 years, they won't immediately bounce back to the iPhone era. But knowing what is possible, they can easily stay at least at mid-19th century level and likely surpass that quite easily.

Some things will be tough. Precision machinery actually may be one of the easier parts. One good machine shop that survives (I think there were 2 in 1632) can bootstrap a lot of other things. On the other hand, integrated circuits will take a long time - you can't build a chip fab out of sticks & stones. But even without a chip fab, and with most of the pre-apocalypse computers gone (and no internet), it won't take long to restart production of some basic computer technology using relays, vacuum tubes and transistors. Unlike the first time around, they won't need to figure what to do or how to do it - just get together enough people who want to do it.

As far as electric power - which is arguably THE key to modern civilization as we know it, solar cells & nuclear power are not gonna' happen. But small-scale hydro and steam (using any available fuel) is simple enough.

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    $\begingroup$ +1 for the reference to a most popular and well-researched series. There were four workshops: two commercial workshops, one in the power plant and one in the high school. People often forget that many schools and high scools offer training in metal and wood working, and thus have decent workshops. $\endgroup$ – AlexP Jun 19 '18 at 12:04

Information priorities become different

The priority is survival. Right now, to survive you need a job, the ability to make money with which you buy food and housing. Post apocalypse you need the ability to find food and shelter, gold is quite low in calories no matter how much of it you have.

That's the extreme example of course. While knowledge may not be lost as such, it can become irrelevant. Your hard earned C++ skills are wasted in a world without electricity. Your knowledge of how to build a large scale power plant is pointless when a 200W PV system covers all your needs.

A lot of what drives science and industry is population pressure, the need to know how to do more than grow potatoes and milk a goat. Without the pressures to need to have the knowledge, it becomes irrelevant. Consider a specialist in large scale international economics, what use is he now? Why would he bother passing that knowledge on? It could be 20 generations before that information is needed again.

Would you rather be working a 60 hour week in an office or weed the potatoes in the morning then spend the rest of the day playing shesh besh with your friends?

The pressures of society drive technology and its uses, while it would take some time for society to drop down to pre-industrial revolution knowledge, it would only take a reduction in numbers and need to reduce to pre-industrial revolution requirements.

You don't need to farm when you can hunt and gather, population pressures require farming. Increased population pressures require intensive farming and on from there back into the industrial revolution. If all your needs are covered by wild plants and hunting, it's not so much that technology is lost, it merely becomes different and much of what we now consider important loses any value.


Long winters are great for technology regression because burning books is a great way to keep from freezing to death. In warmer, more comfortable apocalypse scenarios, a few carefully selected and plastic wrapped text books is all it takes to restore any survivors to early 19th century technology levels.

The only challenge with apocalyptic winters is that the very technology which you are taking from the survivors in return for one night's heat is the only thing that can save them from freezing the next night. Multi-year winters can be survived with artificial grow lights and electric heaters. Without those tools, starvation is likely to prune your survivors down to a story-killing zero.

So you as the world builder, need to walk a tight-rope, providing enough hardship to eliminate the textbooks and others sources of knowledge, while leaving a believable margin for survive-ability. This will be challenging, but not necessarily impossible.

  • $\begingroup$ An idea that might work is having a large supply of the technology needed to survive, but having lost the knowledge of how to produce more of it. It's the situation in WH40K, and it might also work here quite well $\endgroup$ – Sydney Sleeper Jun 18 '18 at 23:09
  • $\begingroup$ @SydneySleeper While WH40K may be a great wargame its plausibility is only sustained by the inmense faith of its fans. The backstory of WH40K has plot holes whole galaxies could fit in. $\endgroup$ – Rekesoft Jun 19 '18 at 9:03

This sort of argument is when I like to bring up my personal theory on Noahs Ark and the literal thousands of sunken cities around the world. Not saying that all of the Noah's Ark story is true or not, but if you had to restart society with just you and your family, even a handful of other random strangers, would you start diving right back into advanced engineer techniques? or would you start off with grass huts and leather tents?

Sure you may have a lot of knowledge on how to rebuild common technologies (like a wheel barrow, a windmill, or a battery), but the survivors acquired that knowledge through years of learning and exposure. Their children and grandchildren will likely be taught much of the basics, but be too busy trying to survive to come close to the same level of knowledge.

This is especially applicable when the population is too low to form a secure community. Teaching would likely be left up to the elderly who would gradually become fewer and fewer as people will begin to die younger from generation to generation with the loss of vaccines and medical technology until it plateaus.

Depending on the type of disaster, the amount of civilization left over basically determines the cap on how much technology they can recover, and that's not to mention the sharp drop in literacy. Who cares if your survivors built a colony inside a massive library if only a handful can read? They don't have time to spend hours learning calculus or physics, they need to scavenge for supplies and farm for food.

Over all, I just think that a lot of the optimism around recovering technology completely disregards the entire issue of basic survival.

  • $\begingroup$ In my opinion, literacy would mostly be gone in 1 maybe 2 generations. the very few that managed to learn to read would eventually be very valuable, however, that may be a couple generations before society gets to the point were they would be needed. $\endgroup$ – Sonvar Jan 18 at 4:01

My opinion would be the regression most likely would come in a form of oppression. Our fondest historical references to innovation in academia and technology come from moments of oppression where culture and religious government oppressed advancement out of fear and control. We may see this after a worldwide apocalypse. People believing that technology destroyed the world push against development. Person to person, re-emerging political governing bodies and spiritual organizations all would affect the rate of advancement. But this would still be temporary as pockets of isolated areas may not come to that conclusion, see technology as a means for gaining an upper hand on a neighbor or simply be havens of optimistic new inventors who have incredible access to already developed technology. We all have looked at a toy as a child and desired to break it to understand how it worked. That fire would reignite once the new world passed from a dark survival period to re-emerging societies.

  • $\begingroup$ Welcome to Worldbuilding, ScottG! If you have a moment, please take the tour and visit the help center to learn more about the site. You may also find Worldbuilding Meta and The Sandbox useful. Here is a meta post on the culture and style of Worldbuilding.SE, just to help you understand our scope and methods, and how we do things here. Have fun! $\endgroup$ – Gryphon Jan 18 at 1:53

Maintaining a high-tech economy requires a lot of people.

I like to think I'm a smart guy. I develop software for a living. So suppose I tried to redevelop technology from scratch. I have a basic understanding of how computers work. Could I "re-invent" the computer? Not likely. I know computer chips are made from silicon and germanium. We get silicon from sand. Cool. How do you turn sand into usable silicon? I haven't the vaguest idea. Where do we get germanium? What does raw germanium in nature look like? I have no idea. Okay, skip to something simpler: We'll need wires. How do you make wire? I don't know. Most wire is made from copper. So we'll have to mine copper ore. What does copper ore look like, and where do you find it? I haven't a clue.

I suspect most intelligent people would be in the same boat that I am. We know a lot about some narrow field. But making that work requires lots of other moving parts, and we know little or nothing about most of them.

And not to be insulting, but most human beings aren't smart enough to build advanced technology. Even with detailed instructions, many couldn't manage it. I've worked in tech support, trust me on this.

If just the right books survived, I presume smart people could figure it out. I suppose that if I knew the apocalypse was coming and I was given access to any experts I needed, I could put together books telling someone how to build various technology, step by step, from zero. Here's where to look for copper ore. Here's what it looks like. Here's how to dig it out and refine it. Here's how to make it into wire. Here's how to make insulation. Etc. up to here's how to assemble all these parts to make a power plant. I'm sure there are books out there on all the pieces of this. But someone trying to rebuild would have to find all those books and read them and understand them and pull it all together. I think that would be very hard.

In a post-apocalyptic world with a greatly reduced population, I think there would be many communities with someone who is an expert electrician ... but who has no idea where to get wire and switches. Another community might have a great miner ... but he has no idea how to refine the metals once mined. Etc. There would be lots of people who know how to do step 7 in some task, but there's no one around who knows how to do step 6 or step 8. Or someone might know how to do a step if only he had the right tools, which he doesn't, because he doesn't know how to make the tools.

  • $\begingroup$ This would be a good point if you dropped off 1 million random people on a fresh new world, but I think there would be enough remnants of old civilization that people could salvage enough stuff to skip many of these steps. At least for a few generations until you can figure out what copper ore looks like, etc. $\endgroup$ – Nosajimiki Jan 17 at 22:34
  • $\begingroup$ @Nosajimiki To some extent: sure. Assuming that people die off from cold weather as the OP discussed, or by an epidemic, or something that doesn't destroy the existing machinery, then the survivors could salvage a lot of existing technology. But how long until things start wearing out or breaking, and can they then maintain them? I guess "materials" would be the easiest part: metal wire could last a long time. But eventually it will rust. I suppose it's a lot easier to figure out how to melt things down and recast them then to mine metals from scratch. Etc. $\endgroup$ – Jay Jan 22 at 15:35

Based on JBH's answer: if things aren't absolutely extinction-level terrible, then it seems to me that the human race can be expected to recover into self-sustaining "local industry" - farming and ranching, printing, masonry, gunpowder, basically 1600 +/- 200 years. Toss in some surviving knowledges.

Consider Amish and Mennonite settlements.

I think the BEST outlook would have smelting and railroads. We'd skip over the telegraph and go straight back to land-line-based telephony. I'm less optimistic about factories, though I'm not sure.

Consider the future-renaissance village: it looks like the stereotypical colonial New England village... but they've also got calculus and arc-lights, and they understand about germs and the sources of disease, they know most of the periodic table, and they can do a lot with chemistry. They have the Jacquard loom, and take full advantage of water wheels and windmills. They might have mechanical adding machines (or they'll just use the abacus). They'll have the "optical telegraph" (heliograph).

If you're edging a bit more into fantasy, they could have functioning Babbage Difference Engines and Analytical Engines.


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