Bezos addresses your final question in the presentation. The livable planetary surfaces other than earth (Moon, Mars, maybe Ganymede or something) aren't that big. In total they sum up to somewhere in the realm of Earth's land surface. So inhabiting them is "only" going to enable doubling the human capacity. Whereas space itself will increase human capacity by many orders of magnitude.
These statements are always fantastical. When we talk about humanity exceeding Earth's resource footprint, the issue isn't land in itself. All of our immediate issues come from balancing:
a) How do we harvest energy
b) How much non-human components do we want to leave, and in what configuration, given that significant non-human components are currently required to give us a livable environment
c) How do we distribute resources
Yes ultimately all of those are constrained by land area, but we have so many other things to solve first before land area is THE problem. And hilariously, it's more or less the same problems we need to solve before we need to colonize anything. How do we efficiently (measured in materials, surface area, maintenance, capital, operating cost) collect energy. How do we create and maintain true closed systems that are reasonably conducive to non-shitty human lives. How do we spread the wealth so we don't burn it all down.
Bezos brings land area into it because assuming a 3% growth in energy usage per year, as has been the historical trend, we will need to cover the earth in solar panels in 200 years.
Something he doesn’t touch on is fission/fusion instead of solar, so I am curious about how that changes the calculus.
3% energy growth is unsustainable in the long run; at that rate we are about 1000 years from using more energy per year than the sun emits in totality:
2015 energy usage 110PWh for the entire year[1]
That works out to ~1.8e13 W average power.
Total output for the sun is about 4e26 W[2]
This works out to about 44 doublings, and 3% growth is a doubling every 24 years which means we need to surpass Kardashev II in 1000 years.
I recognized that as well, but then I realized that "covering the earth in solar panels" is pretty much a dumbed-down description of Type I on the Kardashev scale, which we would eventually, inevitably reach regardless of how we generate power.
Why not make the underground habitats on Earth? If you're going to live underground in a fully self-contained ecosystem why bother traveling to a distant planet?
Or on the surface. The oceans are really big and there's a lot of the surface that has basically nothing going on.
Of course this highlights the problem with all of these habitat ideas: They are placed in locations with limited or no easily accessible natural resources, so their options for sustaining themselves are limited. Obviously you need some farmers and janitors and techs to keep everything running, but beyond that what are they going to do? Building stuff is kind of out of the question because you have to ship in all of the raw materials. So your industry needs to be virtual. Coding, finance, etc... But the world only needs so much of that, and if you keep building colonies you're going to saturate the virtual markets while driving insane demand in the physical markets. The economics are hard to reconcile.
I’m willing to wager that by the time we are concerned about finding homes for another full earth load of humans we will be spreading out far beyond just the Moon and Mars. And, as part of an effort to “back-up” humanity that is a good thing. We should be on many, many planets and in many solar systems.
To that point. If one of these habitats is built the first ones should serve as transit vessels to nearby systems, with the final destination of its crew being a planet.
Additionally, let’s take Bezo’s own logic a step further. When gravity levels are less than that of Earth, say, on the Moon, we we’ll be able to build much higher with greater economy. And we will be able to build into the Moon with greater economy as it is 60% the density of Earth. This effectively increases the livable area, if we are to count “engineered surface area”. The same is true of other planetary and Moon surfaces in our solar system.
You once again are left justifying the effort of building the habitat instead of extending the pre existing available planetary foundation
