The fluff:

A new energy source is invented using the energy of the void and it takes the world by storm. By the time they realise it creates connections to other dimensions it is too late, and nightmarish+fantasy creatures will sporadically spawn in and wreak havoc.

A spawning can range from a few individuals to hundreds of thousands. These spawnings can happen anywhere, and while you have seconds to a minute warning by some sound and ripple effects in the air, it is rather problematic if one creature spawns in your bedroom while you try to sleep for example. The creatures are unpredictable, and can be passive and suddenly attack anything in sight. While moving things are preferred, they have no problem attacking lamp posts, doors, walls, roads, trees etc.

As another side-effect of a spawning is that for hours after a spawning, radio waves stop being able to produce understandable messages and any sub 0.2 micron computer component stops functioning properly, stranding the technology at around 2000 level of technology.

Due to the danger posed by these creatures both the infrastructure and humans have been decimated over time. To survive people are banding together and restructuring their society, losing access to much of their ability to transport people and goods or their agricultural food production.

The question:

To ask my original question I need to know the minimum requirements for a large group of people to survive, create weapons (preferably firearms) to fight off a spawning and maintain a city environment. Lets express it in minimum requirements per X population, say 100.000 people. You are allowed to express it differently if you want. For this question it does not matter how those minimum requirements are met, only what they are.

For clarity the question is: what are the minimum requirements for people to survive and maintain themselves in a city environment?

I'm looking for for the most essential things like clean water.

  • 1
    $\begingroup$ Couple of comments 1) Being limited to 0.2 micron feature size does not lock them into the tech of 2000. Advancements in chip tech like FinFET / GAA, materials advancements, chiplets/EMIB and advancements in processor architectural knowledge still remain or can still be discovered. 2) Y2K computer tech is likely still sufficient for automated sentry guns like S. Korea's Super aEgis II: military.com/video/guns/machine-guns/… so the spawned can get camped (hoho). $\endgroup$ Commented Aug 13, 2021 at 15:12
  • $\begingroup$ Are you interested in material essentials only? According to the survivors of the siege of Leningrad, the daily orchestra performances were essential to their survival. Experiences of concentration camps prisoners also suggest that psychological factors are essential for survival. $\endgroup$
    – Otkin
    Commented Aug 13, 2021 at 17:24
  • $\begingroup$ @GrumpyYoungMan I do not mind if some of such tech is still available. There are some problems getting it though: it is a high-tech turret, the sensors will still have lower performances, the resources are likely limited due to the spawnings and the production facilities+personel will likely suffer damage and casualties. I would expect some of these surrounding important area's, but not available enough for widespread use. That is assuming ofcourse that humans rebuild their society and production in time to handle the spawnings and hoping the production computer systems arent down too much. $\endgroup$
    – Demigan
    Commented Aug 13, 2021 at 17:30
  • $\begingroup$ @Otkin I am not looking for the psychological, mainly the practical. But having a shallow psychological element in your answer is appreciated. $\endgroup$
    – Demigan
    Commented Aug 13, 2021 at 17:32
  • $\begingroup$ @Demigan Unfortunately, my expertise is in social sciences and my understanding of urban planning and similar things is not enough for a good answer. $\endgroup$
    – Otkin
    Commented Aug 13, 2021 at 17:36

1 Answer 1


Let's look at clean water, since it illustrates the problem as well as anything else does. For example, according to https://www.cosatx.us/home/showdocument?id=1010, the processing steps for a water treatment plant are:

  1. Collection
  2. Screening and Straining
  3. Chemical Addition
  4. Coagulation and Flocculation
  5. Sedimentation and Clarification
  6. Filtration
  7. Disinfection
  8. Storage
  9. Distribution

That requires, just from a casual glance, a steady supply of chemical coagulants/flocculants, chlorine additives, filters, maintenance and repair materiel for pipes and tanks, replacement parts for motors, pumps, valves, monitoring equipment, and myriad other things. All of that requires factories which depend on other factories that create plastic and metal parts, various chemicals from chemical plants, etc. and those factories and plants require trained personnel to operate them.

All of those things, in turn, requires raw materials like oil, iron, copper, and other ores, rare earths, etc. And all of those require the specialized facilities to extract them, other facilities to smelt/refine/process them, and the additional trained personnel to operate them too.

Now that just provides the supplies and replacement parts. Additional trained personnel are required on top of that to maintain and perform repairs on the water system and it's not a inconsiderable number.

On top of that, to design new equipment to cope with the situation, you also required a variety of specialized engineers: mechanical, electrical, chemical, civil, etc. to create new designs. And all of those engineering fields are big; like physicians, there are many subspecialties for each of those types of engineers. It takes years of education and on-the-job experience to create an effective engineer.

To finally get to the point: in the industrial age, there an enormous web of dependencies to build everything and that means to maintain an industrial age civilization, they need to maintain and staff a full industrial age supply chain. That means a functioning global transportation network, resource extraction and processing facilities, and a very long chain of manufacturing facilities and if a lot of humanity has been lost, pretty much everyone that's alive is either part of a supply chain or the defense forces protecting them. If they can't do that, then it's game over and they slide back to pre-Industrial Revolution tech rather quickly.

(What about scavenging and building your own local replacements, you say? Jury rigging solutions still requires machine shops, electronics labs, etc. that require their own supplies (cutters/bits, cutting oil, welding rods, etc.) and replacements for equipment that wears out or breaks. And even when it works, the output is still more resource and time intensive that a mass produced product. It's a strategy that can buy some time but it's not a long term solution.)

  • $\begingroup$ yeah cits are the opposite of self sustaining, they need to constantly import to survive. $\endgroup$
    – John
    Commented Aug 14, 2021 at 4:08
  • $\begingroup$ My next question is going to be about exactly what parts of that chain I would still need to rebuild inside the city or keep alive as transport between other cities. This question is more about the rest of the bare necessities. For example water treatment could be partially replaced with more ancient style water treatment like copper lined basins, boiling and straining. If absolutely necessary I would hack it and say they use GMO algea designed to filter, disenfect water and any algea not contaminated as also used as food. That is why the necessities is my goal here. $\endgroup$
    – Demigan
    Commented Aug 14, 2021 at 6:29
  • $\begingroup$ @Demigan Since you're talking about 100k person blocks, I'd go with the algae; the fuel requirements for boiling 100k gal. of H20 (1 gal per person per day) daily is impractical in a post-catastrophe environment. And algae or boiling, the water still has to be delivered. Even if the city abandons pumping for gravity-fed aqueducts (which will be constructed with stone (Quarried from where? Using what equipment? Transported how?) and concrete (Manufactured how?), it requires a natural water source higher than the city. So again we see a modern city requires modern infra. to exist. $\endgroup$ Commented Aug 14, 2021 at 14:52
  • $\begingroup$ @GrumpyYoungMan again, the why, how, where and with what are topics of a future question, and not adequate solutions to survive would actuallg prominently feature in the story. The story would focus on processing the very creatures that attack them, creating a dependency on the very thing that is wearing them down. As for 100k people, that was to offer an indication of what kind of volume I was talking about to avoid questions and answers like "how many people" or "these 10 people survive by murdering others". It wasn't meant as a solid "100k people per cityblock" restriction. $\endgroup$
    – Demigan
    Commented Aug 14, 2021 at 16:08

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