65

I'm going to respond to this with a framing challenge, because as it stands I think you're asking the wrong question. The issue is that the modern industrial world is a product of population DENSITY rather than total population. This may seem semantic but in a post-apocalyptic environment it's very meaningful. Modern industrialism depends on and benefits ...


56

"The events are set in a late renaissance like world, minus the gunpowder." Fine. Let's take this as given, and let's assume that by "late Renaissance-like" we understand western European Renaissance, about 1550 to 1600. "The army doesn't engage in massive battles and is mostly border guard and garrison." Nope, that doesn't work in a western European late-...


28

Ordinary meat takes a lot calories to grow. For example you have to feed a cow 9000 calories for it to gain a pound, and a pound of beef provides roughly 1100 calories. Consuming plants directly would still be able to feed a much larger population that any kind of meat, even if you increased the efficiency of lab meat by 2x or 3x over regular meat. The ...


27

I've used a personal analogy for this, which I call "The brake pad problem." I estimate (without any serious research) that maybe a few hundred people around the world really know what it takes to manufacture an automobile brake pad. If you kill them all off, we're in serious trouble at least until a new process (or a reconstruction of the original) can be ...


26

Oh, the pain... Bedrock is your first problem. You're not building an itsy-bitsy building like the Burj Khalifa or the Tower of Pisa, your'e building the building, the biggest, honkingest, Oorah-est building on the planet. And you're guaranteed to crack the foundation if we don't go all the way down to bedrock, grind the bedrock flat, drill in a bazillion ...


25

Consider a circle. It’s boundary grows linearly with its diameter, but the area within grows as the square of it. Why is this important? Because you’re thinking the wrong way round. You’re thinking of putting your city inside a ring of undefended farmland. What you should do instead is put your farmland inside the city. Give your houses big gardens. ...


24

Your elves will end up cautious. The only way an elf can die is by accident or violence. All other things being equal: the birth rate amongst the various elf demographics is even and pegged to the species death rate, but the inter-group death rates are not equal, therefore the groups that grow the fastest are the ones that die the slowest. Therefore: ...


19

Fielding a big army takes money. Money takes taxes. Your population doesn't want to pay them. What you've described is a big, prosperous country that's gotten fat and lazy off of generations of not having had to fight for anything. Our own history is full of that kind of thing. A nation like that will offer enormous internal resistance to anybody who wants ...


18

Blood, by its very nature, is an oxidant. As such, it's the exact opposite of an anti-oxidant. This may sound obvious, but thinking through the implications a little deeper makes one realise that there are some serious differences to nutrition going on in a vampire's physiology by comparison to a normal human. In point of fact, this is a paradox in how ...


17

First, even before considering demographics. The main problem is, with ageless bodies, the pressure to have descendants lessen or may completely disappear. This kind of immortality brings a whole lot of problems and changes, which are partly solved by the limited numbers of souls. Overpopulation for one. The elf civilization will have two repeating stages. ...


15

Putting a billion people in Yuma, AZ, including food production, industry, and commerce, would require building the entire area to a height of about 2km. The math: Based on the answers on this question, we should be able to feed people using about 25$m^2$ of space, per person, using reasonable near-future assumptions about aeroponic food production. Based ...


13

The New Scientist article "Why the demise of civilisation may be inevitable" from Issue 2650, which is based on the work of Jared Diamond, in particular Collapse suggests that killing as few as 2% of the workforce could initiate a cascade of failures in infrastructure and transportation systems sufficient to bring down modern western civilisation; if those ...


12

A modest shock would be enough to prevent maintaining "our current industrial world". 7nm process semiconductors would become economically infeasible with a sustained 33% global depression, let alone megadeaths. Note, however, that "rare earth minerals" are not rare; they are rare as in "rarer than iron" or carbon or silicon. Rare earth minerals are ...


11

My calculations are very rough. The average weight of a humpback whale is about 25-30 tons, according to Wikipedia. I didn't manage to find any sources for this, but I've seen the estimates of whale bone being about 20% of its weight, leaving us with around 22 tons of muscles, internal organs and blubber. And if they do not eat anything but whale, they are ...


11

No At least, not significantly greater. The theory that the pain of childbirth is what stops humans from having children isn't that substantiated - while childbirth is painful, it's not why people don't want to have children. I suppose on a subconscious level, it might affect a small percentage, which is why I say that it wouldn't make humans significantly ...


10

Yes (and it will happen fairly soon) With the advent of 3d printers it's possible to print meat like products from other products. Eventually society will have algae, bacteria and yeast tanks to produce the food we need. The only problem is it's not exactly appetizing. With additional processing, it can be made into products that have the look, taste and ...


10

Not really. Lab meat only replaces meat, which is only a small fraction of the global diet, and you still need to farm something to feed the lab meat, so there are few gains. That said someday it could easily become less wasteful than traditional ranching, just because you are not growing the whole cow and by using plants and plant byproducts humans will ...


10

Elves will value war. During wartime, childbearing is encouraged, children are valued, and elders are revered. During peacetime, childbearing is strictly regulated (both socially and with the inability to conceive imposed due to lack of souls), having too many children is seen as selfish, and elders are scrutinized for any sign of faltering (there might be ...


10

Based on the initial conditions identified in your question - but also in the comments - the 50 figure is the most realistic. Your population will not be able to resume the practice of agriculture or animal husbandry, if they are limited to "the contents of their pockets". This leaves behind the entire basis for agriculture. Without seeds, they have no ...


10

Political traditions cripple their military. Pick one or several: The parliament or the nobility really doesn't like the monarch to control too many troops. The monarch doesn't want troops under the nobility. The commoners of the cities are expected to provide defensive garrisons, not expeditionary forces. Each craftsman and apprentice owes two days of ...


10

People are too old to go to war. Your /country has very low mortality rates/. They have very low fertility rates. The populace is old. That also accounts in part for why they are stable, rich and peaceful. It is a country like Belgium, or Japan. The old people are rich and sensible. The young people are busy - or foreigners, who are happy to live and ...


10

Forget the walls, build something similar to Catalhuyuk. Catalhuyuk is one of the oldest human settlements we have found, and one of the most prominent theories on its design is specifically to keep out predators. With this design you basically use the outer walls of your buildings as the walls of the settlement. There is no access to any of the buildings ...


9

The US government could hold order; though restore order would be a better term. Also, political power is more local than you suppose. An EMP would be picked up by power lines and likely fry substations and plugged in electrical devices. It might even take out a few power plants, depending on their design. It would also take out most modern cars (because ...


9

Very. Very. Very large. Just for some comparison, have a look at a project of this type being proposed for Tokyo bay. Remember, you're not just building a giant apartment block. You need to account for places people work, create food, eat food, most of the stuff you'd have in a regular city. The structure would house 1,000,000 people. The structure ...


9

Straightforward calculation The initial number of females is N. You pick N. Ten, one hundred, one thousand, your choice. The average life span is S. You pick S. Twenty, thirty years. Each year, an average of D = N / S females will die. (D stands for deaths.) Remember that this is the average life span; it must take into account horrible child mortality, ...


9

It appears that in the Battle of Thymbra, in the Lydia-Persian war (6th century BCE), 100,000 casualties took place in a single day. This was with early Iron Age swords and spears, breasplates and helmets, significantly less advance technology than what you'd see as late as 1000 CE. If the two armies are as large as those at this battle, there's no reason ...


8

As per the work of Robin Dunbar, 150 people seems to be the maximum number of acquaintances you can maintain without forgetting important details, and it'd be pretty dull having to deal with forgetting someone's birthday the 200th time, so I'd say people would probably organize into 100-150 person groups.


8

Hedonistic Population Basically, a stable population that gets used to not having struggle with resources or wars gets to the point where the populace likes that situation (I mean, what's not to like about it?) and then decides to see how much of this 'plentiful food and minimal work' thing they can get away with. Fast forward, and you wind up with a ...


8

So after Thanos snaps his fingers... sorry, I don't know what could've made me think of the MCU movie franchise. Anyway. Things Would Be Pretty Much Unchanged Initially (for months or years), you would see a disaster economy. Vehicles and heavy machinery left unattended would cause damage or fires, and kill more people. Houses left fallow would have to ...


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