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Comment by derekp7 | Hacker News Reader

Two really good literature treatments of your fantasy are Mark Twain's Connecticut Yankee in King Arthur's Court, and Jules Verne's Mysterious Island. They both have as major plot elements a character who has a lot of knowledge of fabrication techniques, and recreate their technology in a primitive situation (one involves time travel, the other is stranded on a primitive island).

On another note, I've heard that the first thing you need to fabricate (beyond basic hand tools) is a lathe. Once you have that, you can make a better lathe, which can make various other machine shop tools, etc. until you have a whole workshop created. Although this probably assumes that you still have access to modern (as in the last couple hundred years) materials to work with.

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I’ve heard of bootstrapping a machine shop from a lathe as well—apparently there’s a series about it, written by this guy: https://en.wikipedia.org/wiki/David_J._Gingery

Gingery did even better than showing how to bootstrap from a lathe. He showed how to bootstrap the lathe itself starting from building a charcoal foundry and chunks of raw metal. Be careful, though: this is a rabbit hole that draws maker-types like rare earth electromagnets. Once you read through Gingery's books, you can easily find yourself wandering down the library stacks and Net pulling up information about how to make more-precise machine tools from less-precise tools.

It is information like this that makes you realize how incredibly fragile our civilization's tech stack is. Most of our physical tech stack is read-only executable code: there isn't a civilizational "source code" that shows from first principles how to build up to our current technology layer. For that matter, not even from first principles to turn of the 20th century technology level. We take a most of our tech stack for granted. This would matter if we had a civilization-wide energy crash, so if the catastrophic-scale climate change or oil crash predictions come true then this would be more than a passing interest for just the recreational primitive tech hobbyists.

If you have a lathe now, how long will it take for that lathe to disintegrate into complete irreparable unusability?

With a fertility rate of 1.3 among the intelligent (read: technologically capable) peoples of the world, we are far more likely to run out of people to maintain the technology than we are to run out of the energy to power it.

Indeed, if you walk into any utility company or similar, who do you see doing all the work? Middle-aged-to-old working-class white men. What happens when those men retire? Who is going to hold the infrastructure together?

Unlike a civilization-wide energy crash, this is not merely a rhetorical question.

That assumes that technologically capable people must be the progeny of technically/technologically capable people, which I put to you is not in any way, shape or form true.

Are you using the number of 1.3 from people with university education in the rich world? It seems a very narrow window through which to view humanity'a 'capable' people, who exist in all shapes and forms, all colours, on all continents, and often arise from deep poverty without any formal education, my grandfather for instance

Technological capability is more or less intellectual ability.

IQ is substantially heritable. A child's IQ is (more or less) the average of his four grandparents. The IQ of his four grandparents is largely the result of cognitive assortment within a breeding population with a certain mean IQ.

If a population's mean IQ is 70, the percentage of people with an IQ above 130 is 0 (out to four decimal places).

If 85, 0.1%.

If 100, 2.2%.

If 115, 15.9%.

The mean IQ of the white race is about 100. The mean IQ of SS Africans is about 70. The mean IQ of Arabs is about 85. The mean IQ of Chinese is 105 or so. The mean IQ of Ashkenazi Jews is 110-115, depending on how you measure it (they are a special case).

There are probably more people possessing IQs of 130 or above in Israel than in all of Africa.

The number 1.3 comes from a rough average of the fertility of the white nations and of the high-end Asian countries, namely Japan, Singapore, Hong Kong, and to a somewhat lesser extent mainland China.

We could recreate society relatively quickly if enough people and artifacts survived and human society itself recovered quickly enough. When people know for certain something is possible they are much more determined to make it happen. Bits of knowledge would trickle through the survivors and help accelerate the process.

Unfortunately during a collapse of society you very rarely find hospitable environments. By the time society itself recovers and has the resources to spare everyone who knew of the old world is dead and a lot of the artifacts are ruined or destroyed.

Seed vaults, storing equipment and books in salt mines, etc should prove extremely helpful if such a dire situation arises. It might take a lot longer to rebuild though because there won't be any cheap, easy oil to burn.

We will have to figure out the "source code" if we make a self sufficient civilization on mars one day?

It may be reassuring (or worrying) to see its resemblance to "battle tested" biological systems. Even the simplest cells can't just "re-evolve" a magically-removed piece, the whole thing comes crashing down.

The winning strategy so far seems to be duplication, so it's about time we get some colonies on other planets to help ensure continuation of the metaspecies.

Another good take on the idea is Lest Darkness Fall, which features time travel to 6th century Rome.

The introduction of stills and proper accounting/math is still one of my favorite bits from that book. :)

I can second this book: written in 1939, but it hasn't dated at all.

Apart from being hilarious and great fun, it's also a suprisingly serious study of just how much technology, and I'm not talking about the modern stuff, is based on a huge pyramid of other skills and technologies which you simply can't leapfrog.

Mild spoilers follow:

Our hero, after being flung back in time to Rome in the year 535, is trying to prevent the fall of the late Roman Empire when it gets conquered by the Byzantines (actually the story's a lot more complex than that, so that's simplified). He tries to reinvent all sort of different pieces of military technology, and fails utterly --- turns out reliable gunpowder is really hard to make. His clocks won't keep time, his lenses aren't round, and he doesn't even both with electricity.

The innovations he eventually ends up successfully introducing? Distilled spirits (a great money-maker!), Arabic notation, double-entry notekeeping, and semaphores.

Based on the old wooden wagons I've seen, lathes played no part in their construction. The spokes on the wheels had been spokeshaved (gee, maybe that's the etymology of that tool's name?) rather than turned on a lathe. The wheels as a whole were pieced together by hand so they'd be round automatically (i.e. spokes and rim segments were all the same length, held together by an iron hoop that just took shape around them when cooled).

Sure this is just one example, but it is what comes to mind given TFA's subject matter. Without access to iron-working, I suppose a less durable rim material like e.g. hemp could be used, which would introduce some more complications involved in tightening. If solid rather than spoked wheels were acceptable, an out-of-round wheel on an axle can be marked with a piece of chalk-rock held in place while spinning the wheel, and then abrasive stones can be used to true the wheel to the chalk mark.

If solid rather than spoked wheels were acceptable, an out-of-round wheel on an axle can be marked with a piece of chalk-rock held in place while spinning the wheel, and then abrasive stones can be used to true the wheel to the chalk mark.

That is a rudimentary lathe.

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