Post-Apocalypse: Back to the Stone Age

[Ji ji]

Modern scientific knowledge goes nowhere without technological applications.
Technological applications require several factors. Among others:

- food surplus
- metal availability
- energy availability

The first factor can definitely lack after a catastrophe. For instance, it can be that atmosphere is darkened by powders and plants are for the large part dead (and consequently there is little fauna and lot of deserts).
The second factor is not so simple, but it should be crucial. It's difficult to imagine a human global society that go back to stone age. More likely, it should be iron age.
The third factor is simple. Electricity is provided by huge power plants, requiring a lot of workers to function. They needs lots of maintenance, unavoidable supply (for nuclear power, but for charcoal or diesel plants too), technicians.
The very knowledge could disappear! Without electricity, the whole digital information baggage become unattainable. Large scale catastrophe can stamp out paper books, that are fragile. New generations are likely to learn abilities more contingent than reading and, when only few readers are left, spreading this ability among others will be painful slow.

Without industry and blast furnace, fire weapons still function, but soon they will lack ammunition. And it's impossible to create new guns or ammunition.

Overall, however, no society can prosper or even mantain old technolocigal development without demographical weight. And no technology can support people when cultivable lands become deserts. Human beings should come back to tribes or chefferies, hunting little game, and fighting among them for the scarse available resources.