Eliezer S. Yudkowsky wrote:
> The worst part is, the blasted answer is probably obvious. I've got the
> feeling that this whole problem was set up DELIBERATELY, as a means of
> communication, so that there's only one *possible* answer, which is
> immediately obvious to the first transhuman on the planet. I'm smart
> enough to hear Them screaming the answer in my ear, but not
> smart enough to understand it.
Why do you assume there is someone out there?
IMHO, the most economical explanation of our observations is simply that the average time required for a life-bearing world to produce a technological civilization is much longer than the average time that pre-technological life can survive in a single location. Given what we know about stellar lifespans and the frequency of cataclysmic events (nearby subernovae, GRBs, close encounters with other stars or black holes, etc), this isn't all that big of a stretch. We have to make some pessimistic assumptions about the natural rate of evolution, but that's a subject with plenty of big unknowns.
We can also tip the statistics a bit in our favor by noting that the concentration of heavy elements in the universe has been slowly increasing ever since the big bang. Earthlike planets could not have formed in the early universe, and planets with an Earthlike chemical composition have probably only existed recently.
Billy Brown, MCSE+I