> We aren't machines that can trivially reproduce ourselves from commonly available materials and then eject into space.
Nah, we use plants to turn raw materials into what we can consume. And in the other direction, we can only make stuff on this scale with factories that take a while to build. But in both cases, that's a distinction without a difference. A farm and a factory rather than a spacesuit, makes no difference on this scale, so long as they feed themselves while growing their families.
> Feeding ourselves is hard, getting to space (alive) is harder.
Feeding ourselves is about 1% of our current labour. Getting into space is only hard because we use rockets, but at this scale we'd use launch loops, atlas towers, orbital rings, or similar. Those are extremely cheap, like "$300 to LEO" cheap for this thought experiment's ("spherical cow in a vacuum" model of a) 100 kg human.
> And once the overwhelming majority of us are in space because there's no more room down below, how are we supposed to meet up to keep up the 25 year doubling rate. How are we supposed to keep up the rate of resource extraction from Earth?
There's lots of ways I've seen suggested. Even without the exotic options like the Dyson Motor (would take too long, at 40k years for Earth, not seen the numbers for Luna or Mars) or redirecting Kupier Belt Objects to blow off percentage points of the target planet mass at a time, even just with traditional digging, at that scale it's "how fast can you drill vertically?" and "how many launch loops can you wrap the target planet in?", followed by "how fast does the deep ground cool down when exposed?" — the latter being why I said thermodynamics probably gets in the way when the timeline gets down to decades; this is radiative-dominated cooling in a better vacuum (insulator!) than most laboratories let alone thermos-flasks.
Nah, we use plants to turn raw materials into what we can consume. And in the other direction, we can only make stuff on this scale with factories that take a while to build. But in both cases, that's a distinction without a difference. A farm and a factory rather than a spacesuit, makes no difference on this scale, so long as they feed themselves while growing their families.
> Feeding ourselves is hard, getting to space (alive) is harder.
Feeding ourselves is about 1% of our current labour. Getting into space is only hard because we use rockets, but at this scale we'd use launch loops, atlas towers, orbital rings, or similar. Those are extremely cheap, like "$300 to LEO" cheap for this thought experiment's ("spherical cow in a vacuum" model of a) 100 kg human.
> And once the overwhelming majority of us are in space because there's no more room down below, how are we supposed to meet up to keep up the 25 year doubling rate. How are we supposed to keep up the rate of resource extraction from Earth?
There's lots of ways I've seen suggested. Even without the exotic options like the Dyson Motor (would take too long, at 40k years for Earth, not seen the numbers for Luna or Mars) or redirecting Kupier Belt Objects to blow off percentage points of the target planet mass at a time, even just with traditional digging, at that scale it's "how fast can you drill vertically?" and "how many launch loops can you wrap the target planet in?", followed by "how fast does the deep ground cool down when exposed?" — the latter being why I said thermodynamics probably gets in the way when the timeline gets down to decades; this is radiative-dominated cooling in a better vacuum (insulator!) than most laboratories let alone thermos-flasks.