[TeMPOraL]

Computers and hard drives have half-life counted in years, and need energy and communication infrastructure to operate. Post-collapse, once all the computers break down, that's the end of XX-century technology. Nobody is going to make new ones, because to build and maintain machines that make computers you need working computers. Same for mining and refining necessary resources, controlling chemical processes, etc.

Whatever technological knowledge survives in the books, most of it will be useless for centuries, as we regress into pre-industrial level of technology and can't climb back out - we've already mined out all easily-accessible high-density energy sources that are necessary for reindustrialization.

[int_19h]

Why would we regress to pre-industrial level of technology? Even if you somehow wipe 90% of the population worldwide, this brings the population back to mid-18th century levels - which is to say, when industrial revolution was already ongoing. But that same number of people would know all the things that had to be discovered back then, and would still have a lot of machinery, and a lot of already-refined materials, to bootstrap from.

Nor is there a particular shortage of hydrocarbons to burn, with consumption reduced so much due to population loss and reduction in quality of life. Consider that US today emits more than 200x carbon into the atmosphere than it did in 1850, and that this growth has been exponential. So what we consider one year worth of reserves today, could provide energy for many decades in this hypothetical.

[drran]

If resources are already mined, why we need to mine them again?

Simple computers are relatively easy to make with today tech. Software exists already.