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TomD
Obviously, you could plot a graph with the x axis being total human population and the y axis being some amalgam of average human well being. I’m pretty sure it won’t graph as an exponential function, that’s impossible. It would be a bell shaped curve with maximum human happiness occurring at some level and declining in both direction, more population or less.
The population peak, I suspect, will occur at the point of maximum available resources, including energy per capita. And I also suspect that increasing resource availability largely pulls population as opposed to population increase pushing resources.
Total available energy per capita may well be the bottleneck. But there will come a point at which the total resources of a large but closed system cannot continue to increase to match.
There are probably other limits. A future with the average population density on earth being that of Hong Kong, no matter resource availability, would explode.
Maybe we could start hollowing out large asteroids, spin them, and make little worlds. That’s a common SF scenario. Or a Dyson sphere, one of those of radius of the earth’s orbit would give 1.21 x 10^17th square miles of living space.