Re: MEDIA: NOVA on Gamma Ray Bursters

From: Anders Sandberg (
Date: Wed Jan 09 2002 - 09:28:17 MST

On Wed, Jan 09, 2002 at 11:05:30AM -0500, Mike Lorrey wrote:
> You know, dealing with the "sun is mostly iron" thread, lets assume that
> our suns 'supernova' 5 billion years ago produced a GRB that wiped out
> life in a radius of x light years from the Sun. How big a radius would
> that be, and could the Fermi paradox be explained by intelligent
> spacefaring races avoiding our region, expecting no life to exist here
> due to the GRB?

I don't think it would work (too bad, it was a nice new take on Fermi).
The sun rotates around the galaxy every 250 million years, and there is
some mixing going on due to differential rotation and stars having
different velocities, so the dead zone due to a GRB 20 galactic years
ago would by now be smeared across the disc into some kind of diffuse
band mixed with other stars. Plenty of the stars in the sun's vicinity
are younger than five billion years, and if they formed with planetary
systems these systems could have evolved life and intelligence in the
meantime (assuming the Earth was a bit slow in doing it). If the GRB
wiped out everything within a few hundred thousand ly, then we might be
alone in a sterilized galaxy, but that seems rather extreme -
supernovae are not GRBs.

Anders Sandberg                                      Towards Ascension!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y

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