But the chief limitation in the preceding analysis is Earth’s surface area—pleasant as it is. We only gain 16 years by collecting the extra 30% of energy immediately bouncing away, so the great expense of placing an Earth-encircling photovoltaic array in space is surely not worth the effort. But why confine ourselves to the Earth, once in space? Let’s think big: surround the sun with solar panels. And while we’re at it, let’s again make them 100% efficient. Never-mind the fact that a 4 mm-thick structure surrounding the sun at the distance of Earth’s orbit would require one Earth’s worth of materials—and specialized materials at that. Doing so allows us to continue 2.3% annual energy growth for 1350 years from the present time.
At this point you may realize that our sun is not the only star in the galaxy. The Milky Way galaxy hosts about 100 billion stars. Lots of energy just spewing into space, there for the taking. Recall that each factor of ten takes us 100 years down the road. One-hundred billion is eleven factors of ten, so 1100 additional years. Thus in about 2500 years from now, we would be using a large galaxy’s worth of energy.
In other words, keep up the paltry growth rate listed at the start of the essay, and take the fantastically-favorable assumptions that go with it (like 100% efficiency) and you find that even if we’re surrounding every star in Dyson spheres we can’t keep up with growth, because within relatively short timescales we are consuming a whole galaxy’s worth of energy. (At that point, we have to stop growing unless you think we can somehow harness ~3% of another galaxy within the next year after capping out our own, or for that matter spread across the entire Milky Way in 2500 years -- this is trivially, obviously absurd unless you bring FTL into the equation, and even attaining a few percent of c is currently unthinkable in practical terms).
Also, you’re missing the point of the essay—that this picture emerges from the most ludicrously favorable assumptions in favor of continued growth: that we can only focus on growing the energy sector to the exclusion of worrying about anything else, and that we don’t need to worry about thermodynamic limits to efficiency, and that we don’t need to worry about a piddly little thing like the speed of light once we’ve enclosed the sun in a Dyson sphere and need to keep up the growth rate by expanding into the galaxy at large. Even with that working in favor, we eventually run out of galaxy and have to stop growing. Once you understand that, the only thing left to be argued is where the inflection point lies.
Saying that limits to growth is an argument in favor of civilizations being more likely to spread out, is like saying that the possibility of extinction is an argument in favor of some arbitrary evolutionary adaptation in a population of organisms. It’s getting the important causal bits backwards.
Nnnooooo, read it again.
In other words, keep up the paltry growth rate listed at the start of the essay, and take the fantastically-favorable assumptions that go with it (like 100% efficiency) and you find that even if we’re surrounding every star in Dyson spheres we can’t keep up with growth, because within relatively short timescales we are consuming a whole galaxy’s worth of energy. (At that point, we have to stop growing unless you think we can somehow harness ~3% of another galaxy within the next year after capping out our own, or for that matter spread across the entire Milky Way in 2500 years -- this is trivially, obviously absurd unless you bring FTL into the equation, and even attaining a few percent of c is currently unthinkable in practical terms).
Also, you’re missing the point of the essay—that this picture emerges from the most ludicrously favorable assumptions in favor of continued growth: that we can only focus on growing the energy sector to the exclusion of worrying about anything else, and that we don’t need to worry about thermodynamic limits to efficiency, and that we don’t need to worry about a piddly little thing like the speed of light once we’ve enclosed the sun in a Dyson sphere and need to keep up the growth rate by expanding into the galaxy at large. Even with that working in favor, we eventually run out of galaxy and have to stop growing. Once you understand that, the only thing left to be argued is where the inflection point lies.
Saying that limits to growth is an argument in favor of civilizations being more likely to spread out, is like saying that the possibility of extinction is an argument in favor of some arbitrary evolutionary adaptation in a population of organisms. It’s getting the important causal bits backwards.