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Comment by galcerte | Hacker News Reader

In that case, if you want a somewhat entertaining very-high-level overview of what would need to be done, then there's a manga that showed this off a few chapters ago, it's called Dr. Stone. What stuck with me the most was that the purity needed for the silicon used in processors was absurdly high, so much so that they couldn't quite do that just yet, so they made a processor out of parametrons and used magnetic core memory. I knew semiconductors had to be very pure, but it was a bit discouraging to realize just how much effort it would take if you started from zero.

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Dr. Stone is great but I also found it to be a bit too hand-wavy. In real life you can't just build steam engines with a small village worth of labor + a "master craftsman". Mining, transporting, and refining iron ore alone is a huge task that could easily consume every drop of the village's labor resources and still not produce much iron. Fuel is also a huge task. Unless you have a high quality coal mine nearby, you have to create charcoal which is also very labor intensive (see: https://www.youtube.com/watch?v=GzLvqCTvOQY). I just can't fathom how Senku realistically makes processors unless he has a nation state worth of labor at his disposal.

But yeah, it is a fun "what if".

"What if a super genius with the entirety of wikipedia in his brain were sent back to the stone age? Could he rebuild modern society?"

At least with iron, you'd have the benefit of the existing refined ore lying all around you in a post-apocalyptic setting. There's little need for actually mining iron ore anymore if your population has been reduced by 99% or more. You can walk down any abandoned street and find sources of iron and other metals. Now, there's still the refining process (but it would be shorter from something already processed) and fuel to contend with.

IIRC a key obstacle why steam engines were not used earlier despite the concept being known for at least a millenium was the requirement for quite advanced metallurgy - you can make a nifty proof of concept from copper or iron, but a useful steam engine needs to be (a) relatively high pressure and (b) large, so you can do it only if you can reliably and cheaply make large quantities of decent steel. If you can't make large quantities of steel, your steam engine doesn't work; if your steel-making process has unpredictable results, then your boiler blows up at a weak spot, and if that steel is expensive, you're better off having the same people work a literal treadmill instead of making a steam machine.

Also, making glass is not just combining sand and seashells and fire.

I don't doubt that they could have made glass plates or something, but they start turning out vacuum tubes and borosilicate beakers next to each other like it was all a matter of knowing the recipe.

>the purity needed for the silicon used in processors was absurdly high

Yes. Silicon wafers are cut from a monocrystalline boule, a single flawless silicon crystal with no defects or inclusions. A big chunk of silicon atoms, nothing else at all. (Doping happens later) To the extent any physical object can be called "perfect", a semiconductor wafer is perfect.

(Of course after manufacturing it will start picking up embedded hydrogen and helium atoms from cosmic rays and alpha particle background radiation.)

Wow, no idea Dr. Stone was that hardcore. That sounds watchable!

edit: didn’t pay attention that you were talking about the manga. That makes more sense. Sounds highly readable!

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