[ExI] Panbiogenesis

BillK pharos at gmail.com
Fri Jan 27 10:45:36 UTC 2012

On Fri, Jan 27, 2012 at 10:02 AM, Anders Sandberg  wrote:
> That is the important point. Panspermia depends on very unlikely events, but
> there is so long time and so many planets that it has a chance.
> Consider a biosphere lasting 5 billion years, that manages to seed just one
> other planet out of (say) 10 billion available in the galaxy.  That means a
> probability of 1 in 50 billion billion per year. A slightly higher
> probability in this model, and more planets will be seeded and the galaxy
> will "quickly" be colonized.

That is very similar maths logic as to why the galaxy should have
already been colonised by the first expansive space-faring species.
What's fascinating about the Hair and Hedman paper is that they are
not cosmologists or astrobiologists, but rather mathematicians—and it
is through the lens of number-cruching that they sought an answer to
the question of how long it would take a civilization to colonize its
local region given a specific set of parameters. And their findings
are disturbing: No matter how they reworked the numbers, they came to
the same conclusion: the Galaxy should be colonized by now:

(Apparently the paper is not available online yet)


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