We may have the technology to create massive habitats in the near future, but what if we do not have the need.
Population is projected to plateau in the near future. What if those habitats exist but just are not observable since they are quite small compared to their stars / planets?
Isaac Arthur deals with this at length in his videos. Those projections are unlikely to hold for long. Cultures that don't expand will quickly be replaced by those who do and the process continues. Population expansion is limited only really by resources.
You see this in all other species, but we somehow think it's different for us. That remains to be seen.
We think it's different for us because the reversal in population growth is correlated with education and development levels. These are factors which aren't present in animal populations.
If we lived in a world where every culture had achieved a certain level of education and development (and most all of them do want to get there), it's likely they would all have flat or declining populations. They might have to heavily subsidize reproduction just to sustain themselves and all this talk about building space habitats would be even more abstract than it is today.
This seems to currently be a thing. It's a little premature to say it's going to apply to all cultures across all time. In fact I'd take the opposite side of that bet.
The thing is if there's any culture for which that's not true, like Mormons, Orthodox Jews, some groups of Muslims, whatever. In a few generations they replace the cultures that don't have a lot of children like our own. Then expansion continues.
I could see expansion slowing even reversing temporarily, but it seems hard to imagine it permanently ending.
Well, while they're still dominant, all the other cultures might decide to band together and discourage, eradicate or dilute the one that keeps growing.
Anyway I agree that we can't say for certain whether population will grow or shrink. In fact in the context of this discussion I think that's the most important point. Many discussions about alien civilizations tend to assume that they'll evolve into huge multiplanetary populations with large energy/EM/whatever footprints. When in reality our most developed cultures are slowly declining in population. If an underground cache of brains in pleasure boxes is the end stage for most civs we will probably never know.
That's a good point, and one I often wonder about too. Maybe advanced civilizations are not expansionist. However it doesn't make a good solution to Fermi's Paradox because all civilizations would have to not be expansionist, if there were just a few exceptions they'd expand all over and we'd likely spot them.
This is simple linear thinking and a lack of imagination. As well as empirically wrong. Population expansion in humans ended because our culture adapted to the end of child mortality. Actually the massive expansion we saw and see was because culture took a few generations to do so. As soon as we conquer mortality as such our culture will shift again.
And that is only thinking about the impact of tech we might see this century.
Exponential growth is really a phenomenon of transitions. We are in a very rapid 10.000 year transition from biological system to cultural system. This transition accelerated further in the last two centuries. If we think about the end point of this transition it should be a system that is entirely defined by its culture rather than by its biology. Maybe even completely away from its biology. It's fun but idle to speculate what that culture will be like, but if experiences can be shared as easily as text today, what is the value of having billions of copies of similar experiences? What _is_ an individual in that situation?
Even if we accept your simple expansion/competition/ressources based model of reality* (and I see no reason we should) maybe combining consciousnesses leads to much better results. Maybe expansion will look like ever increasing use of energy resources to enable larger consciousness rather than maintaining more animal bodies.
Population is projected to plateau in the near future. What if those habitats exist but just are not observable since they are quite small compared to their stars / planets?