Right, but he's also expressed scepticism that you could produce arbitrarily high value per atom. Ah, found the link and it was in the context of the number of people-equivalents worth of value we could produce per atom:
It seems just physically impossible to create 10^140 or more lives we would value like ours per atom, even considering quantum computing and black hole negentropy. But could individual living standards be that high?
To say that someone had a standard of living 10^140 times a subsistence level means that 10^-140 of their income could buy a subsistence level standard of living. Someone with a subsistence level living standard, and a square root type risk-aversion, would reject an offer to jump to today’s world average living standard, twenty times higher, if they could instead roll 69 ten-sided dice, and only get to jump to this 10^140 higher standard if all the dice came up 1. (Someone with a fourth root risk aversion would prefer to roll 35 dies.) That is just how incredibly fantastic this 10^140 higher living standard would be. A living standard 10^2950 higher is far far more fantastic.
Ah, thanks for that - I just remembered the pithy soundbite.
A dialogue discussing how thermodynamics limits future growth in energy usage, and that in turn limits GDP growth, from the blog Do the Math.
I think this is quite relevant to many of the ideas of futurism (and economics) that we often discuss here on Less Wrong. They address the concepts related to levels of civilization and mind uploading. Colonization of space is dismissed by both parties, at least for the sake of the discussion. The blog author has another post discussing his views on its implausibility; I find it to be somewhat limited in its consideration of the issue, though.
He has also detailed the calculations whose results he describes in this dialogue in a few previous posts. The dialogue format will probably be a kinder introduction to the ideas for those less mathematically inclined.