<Snipped quote by Dinh AaronMk>First off, microchipps don't require rare elements as an explicit need. Second, they are found outside of Congo.
Actually no. While materials like Cobalt may be found in China they are fundamentally much more common and accessible in the Congo than elsewhere.
The greener the blob, the more there is.
Other important computational materials also have a limited range or have to be pulled from baser metals, like the
Neodymium inside of hard-drives. And the other materials required are a massive and mundane undertaking, more so in refining these materials out or for use in high-tech equipment. And in post-apocalypse societies we're dealing with a world that should be more concerned internally on its own survival: you got to feed your people and defend them while managing the already limited array amount of resources already present.
just like guns many seemingly advanced technologies are relatively easy to produce with sufficient knowledge in less developed environments (though microchips are of course not them).
This is the point where I wonder if you read everything. Guns yes could be reproduced very easily without modern methods. Good parts from previous - if badly damaged - weapons could be re-purposed to make new weapons (as-in the practice of the as-so-mentioned Khyber Pass guns). But production of moving-part combustion engines from straight raw material would be a more difficult task.
Railguns and carbon-nanotubes are surprisingly among these. The latter was involved in the creation of Damascus Steel, for example.
Electromagnetic technology in general benefits from having few complex moving parts.
Uranium is one of those materials that like above need to be refined out of existing metals, namely a very specefic isotope of iron. And the metals needed for the magnets are intensely rare. you're not going to build one out of ceramic magnets. Even neodynium magnets aren't going to work. We're talking using
Terbium and non-naturally occurring
Dysprosi.
And the carbon nano-tubes present in Damascus Steel are not the same sort of carbon nano-tubes required for present high-tech. These structures are much smaller than the tubes already provided in "My Little NanoScience Starter Kits" you can get online. The sorts naturally occuring in bio-mass fires are much shorter to be used industrially in their relevant fields. You need lasers. Lasers need specialized miced-out optics, energy storage, and their own specialized mirrors.
Third, while this is a good excuse for low tech or shizo tech environment nothing really stops people from using something better. Aircraft and pre-war tech is all but endorsed by the OP also things are fine enough that global relations are becoming a thing again.
While in a writing world you can't stop someone from saying they can, it doesn't stop that in the actual setting that yes: there would be something stopping them. Namely the limitations in the resources to continue operating the machines or acquiring the non-native metals needed to produce them. And when you need to rebuild society there are other focuses that need to be played out first: you need to make sure the people and your army is fed. Its a lot harder to feed a population when you can't use mechanical tractors. You'll be putting more people out in the field with sickles and scythes than with a combine tractor. This requires far greater man-power in necessary labor so there'd be less available to practice science and engineering.
And even when the food is addressed it still needs to be distributed. You need people to also protect this populations. The levees, conscripts, or levees in an army aren't going to have time for research between drills or watching for and fending off raiders.
So when it gets broken down to a society that's not a century out of the shelters there's not a lot of people left behind to innovate new tech and the most economical option would be to keep what little is left operating running. But they'll get to a point where those can't be maintained anymore.
And who said the vault-dwellers just sit around and did nothing during this time. If they wanted to keep their lifestyle developing means to maintain their tech was one step they got to take.
There's a difference between knowing and having the means to make shit. When the production chain and facilities to make a Toyota are gone, then no amount of a mechanical engineering degree can save that. And when you have two (possibly three) generations living in a disconnected world reading text books and manuals on how to build a Toyota Camry they're not going to know how to deal with the Fordoyta Frankensteins that are rolling about.
Neither are they going to be able to handle everything else.
And in a world where we have nations to the size they are now it'd be appropriate to admit that not everyone went into a shelter. So there's a super-minority of academic individuals in a world that rebuilt itself to survival after the modern nation-state. And in a world where all nations disappeared as they did then the amount of nuclear war had to be beyond absolute. Life can survive that: but political institutions as we know them and everything else would not. They'd be a concept on paper but there'd be no way for any of that to actually be put to work beyond a constant recycling or pre-existing parts until they themselves died.
The main issue isn't know-how, it's the supply chain. And without the logistics network behind the know-how all that knowledge is useless. Generations after stepping out of the vault many might decide to forget their previous knowledge in favor of the more directly relevant skills on how to swap out a AK-74's firing mechanism onto the stock of a FAMAS. Or how to grow food again.
There's also the matter that seventy-years after the present day and after the bombs dropped no one would be making anything by hand anymore. So there'd be very few people with the personal experience of building much of anything which renders a lot of that moot. They might go into the vault knowing how to program how to manufacture an iPod into a 3d printer or model the cuts needed for a computer-operated milling machine to router out something, but the value of these machines die when no one knows how to use them, they were stripped and broken down for parts already, or the router bits are gone.
When you step into the world of rubbers and plastics, the supply-lines behind the modern world are broken down. Ultimately rubber seals will deteriorate, plastic will bake and harden until brittle, and metal tanks will rot out. The climate-conditioning for server plantations stop working and when the perfect environment for maintaining the circuits fail they too rot away and data is lost. And unless an empire maintains a rubber plantation in Sri Lanka or the frakking infrastructure (which is itself large and reliant on its own massive production chain) then rubber will not be produced for seals, hosing, or wire housing. The world would be at a level comparable to a more wood-and-metal era like the mid 19th century where leather seals and casings was all that's needed, and copper was the most effective medium of carrying an electrical current. Computers - if and when produced - would be the size of warehouses with the computational efficiency of a modern calculator but with no graphical read-outs.
