From: Anders Sandberg (asa@nada.kth.se)
Date: Wed Jan 06 1999 - 05:16:46 MST
patrick.wilken@infotech.monash.edu.au (Patrick Wilken) writes:
> >We must also
> >see that the gaps between galactic arms are really rather wide and are a
> >hindrance to expansion.
>
> Stanislaw Lem -- in the 'World as Cataclysm' (One Human Minute, 1986) --
> argues that the early solar system spent time in a galactic arm where
> stellar explosions were common (and which he argues were a necessary
> precursor to life), but then shortly thereafter left for the quieter spaces
> between arms. By being in the relatively empty spaces ensured that life was
> not too quickly snuffed out by nearby supernovae (which would have occurred
> if we were near the center or stuck within a spiral arm).
>
> Anyone want to voice an opinion on how this argument has stood the test of
> time? I find its most interesting feature that it contradicts the
> underlying belief that we are on a very average star in a very average
> point in the galaxy. On the contrary if Lem is right its only in particular
> places (approx. 34k light years from the center - where stars pass through
> the arms on a regular, but not too fast pace) that life-bearing star
> systems can emerge.
As far as I know the sun passes through the spiral arms in its orbit,
so there should be a few passages every galactic year (250 million
years, if I'm not misremembering). So Lem's idea haven't held up well,
although he might still argue that it is likelier for intelligence to
evolve on stars in quieter areas sinply because of a lower risk of
mass extinctions (but on the other hand, they tend to cause
evolutionary radiations).
-- ----------------------------------------------------------------------- Anders Sandberg Towards Ascension! asa@nada.kth.se http://www.nada.kth.se/~asa/ GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y
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