= 27d567bc2d48d9f40e9ccc20ea370b15)
steven0461 comments on One possible issue with radically increased lifespan - Less Wrong Discussion
You are viewing a comment permalink. View the original post to see all comments and the full post content.
= 783df68a0f980790206b9ea87794c5b6)
Loading…= b715d02e85f7b3b4ae65ca3d3e450868)
Subscribe to RSS Feed
Powered by Reddit
= f037147d6e6c911a85753b9abdedda8d)
You are viewing a comment permalink. View the original post to see all comments and the full post content.
Comments (85)
This reminds me. An interesting question is, assuming constant mass/person, how long until the speed of light becomes a limiting factor? I.e. given a fixed growth rate, at what total population would the colonization speed be approaching the speed of light just to keep the # humans per cubic parsec of space constant? It is clear that this will happen at some point, given the assumptions of constant birth rate and constant body mass, because the volume of colonized space only grows as time cubed, while the population grows exponentially.
Here is a back-of-the-envelope stab at it. I have not googled it beforehand, because it's fun to do one's own estimate.
Assume 1 habitable planet (10^10 people) per cubic light year, the total colonized number of planets ~ #years^3 after the onset of interstellar travel at near light speed. (I am not accounting for the relativistic time dilation, though the correction should be small, since only a minority of people are in-flight at any given time.) I'm ignoring the factors of the order of 1, such as 4 pi/3 for the volume of a sphere.
Assume 0.1%/year growth rate. This is about 1/20 of the current birth rate. Total number of occupied planets = 1.001^(#years).
The two numbers become comparable after about 30,000 years. This is less than one third of the size of the Milky Way galaxy (in light years). After that, the population growth will be limited by the known physical laws, long before other galaxies are explored.
Other physical angles:
If the economy continues to grow at roughly the present rate, using more energy as it does so, when will we be consuming the entire solar energy output each year? And if this energy growth happens on the surface of the earth and heat dissipation works in a naive way then how long till the surface of the earth is as hot as the sun? Answers: A bit less than 1400 years from now to be eating the sun, and a bit less than 1000 years from now till Earth's surface is equally hot, respectively. Blog post citation!
The same blogger did a followup post on the possibility of economic growth that "virtualizes our values" (my terminology, not the blogger's, he calls it "decoupling") so that humanity gets gazillions of dollars worth of something while energy use is fixed by fiat in the model. Necessarily the "fluffy stuff" (his term) somehow takes over the economy such that things like food are negligible to economic activity. With 5% "total economy" growth and up-to-an-asymptote energy growth, by 2080 98% percent of the value of the economy is made of of "fluffy stuff" which seems to imply that real world food and real world gasoline would be less than 2% of the economy... which implies that the average paycheck would be spent on very very little food or gas and quite a lot on "fluffy stuff".
The blogger takes this as evidence that the fluffy economy is impossible and (implicitly) that we should just accept that civilization has peaked and should turn into lowered-expectations-hippies, but to me his "ridiculous" energy scenario sounds suspiciously similar to Hanson's em scenario. What use has an em for a real hamburger made out of real beef grown with real grass shined on by real sunshine? Very little use. It would be like having the deed to an extrasolar planet. How awesome would it be to be an em? Very much awesome :-)
See an earlier discussion for some more criticism of the blogger's claim.