Re: The Great Filter

Robin Hanson (
Mon, 10 Mar 1997 13:14:37 -0800 (PST)

Forrest Bishop writes:
>Not quite- consider the mixing that occurs as star systems circulate
>about the galaxy. ... The ensuing structure of
>dead (or unicellular life) and (complex)living systems might be more of
>a scattered 3D mosaic, peppered with the more recent dead zones.

Oops, you're right. But it would be plausible for our solar system
all the way out through our bound comets to be teaming with life.

If multi-celluar life on a planet gets destroyed every 100my, then
this should happen on average 100 times over 10by. So the chance it
never happened at any one place is exp(100) ~= 10^-43 (assuming a
poisson distribution). So how big is a sphere enclosing 10^43 stars?

Robin D. Hanson