Assuming survival of some libraries, I think basically any medium-sized functional village (thousands of people, or hundreds with a dash of trade) is adequate to maintain iron age technology. That’s valuable enough that any group that survived in a fixed location for more than a couple years could see the value in the investment. (You might not even need the libraries if the right sort of person survived; I suspect I could get a lot of it without that, but it would be a lot less efficient.)
It doesn’t take all that much more beyond that to get to some mix of 17th to 19th century tech. Building a useful early 19th-century machine shop is the work of one or two people, full time, for several years. Even in the presence of scavenging, I think such technology is useful enough that it won’t take that long to be worth spending time on.
Basically I think anything that’s survivable is unlikely to regress to before 17th century tech for a period longer than a few years.
If only one village survive, it will use scavenging of nearby city for decades and during this time it will lost most high educated people.
But lets assume that scavenging economy is no possible, may be this village survive on remote island, which is probable, in case of pandemic.
In this case the main problem will be economy of scale, chemistry and raw materials. Even 19 century economy is based on available coal, iron ore, copper and some other things. Most of them require very specific people, knowledges and instruments to find and produce.
And also they are economically useful only if it is done in the medium size european country.
And finally most ores which were easily available in 19 century are now depleted or not present at all in remote islands.
So if a village survive on an island it will not be able to build steampowered ship in next few years to explore surrounding.
I also would not overestimate the ability of random people to study new science like geology, using only books, without proper training and control.
I think you’re pessimistic about tech regression.
Assuming survival of some libraries, I think basically any medium-sized functional village (thousands of people, or hundreds with a dash of trade) is adequate to maintain iron age technology. That’s valuable enough that any group that survived in a fixed location for more than a couple years could see the value in the investment. (You might not even need the libraries if the right sort of person survived; I suspect I could get a lot of it without that, but it would be a lot less efficient.)
It doesn’t take all that much more beyond that to get to some mix of 17th to 19th century tech. Building a useful early 19th-century machine shop is the work of one or two people, full time, for several years. Even in the presence of scavenging, I think such technology is useful enough that it won’t take that long to be worth spending time on.
Basically I think anything that’s survivable is unlikely to regress to before 17th century tech for a period longer than a few years.
If only one village survive, it will use scavenging of nearby city for decades and during this time it will lost most high educated people.
But lets assume that scavenging economy is no possible, may be this village survive on remote island, which is probable, in case of pandemic.
In this case the main problem will be economy of scale, chemistry and raw materials. Even 19 century economy is based on available coal, iron ore, copper and some other things. Most of them require very specific people, knowledges and instruments to find and produce.
And also they are economically useful only if it is done in the medium size european country.
And finally most ores which were easily available in 19 century are now depleted or not present at all in remote islands. So if a village survive on an island it will not be able to build steampowered ship in next few years to explore surrounding. I also would not overestimate the ability of random people to study new science like geology, using only books, without proper training and control.