Re: >H Re: The Great Filter

Forrest Bishop (
Sun, 16 Mar 1997 15:18:04 -0600 (CST)

Paul Dietz, Michael Lorrey, Curt Adams wrote:
>> Is a relatively (pardon the pun) nearby, but beyond the lethal
radius (say
>> 2000 light-years) neutron star binary collapse a plausible cause for
>> extinctions?
>That technicium levels in molybdenum deposits indicate the existence
>such gamma ray bursters in our own geological past (supposedly the
>cretaceous), .....

I wonder if candidate radioactive decay products have or can be found
at the boundaries of the really big extinctions (e.g Permian).

>preserves, possibly in the cores of asteroids or dead moons like our
>own. Several hundred miles of solid rock in every direction should be
>enough sheilding against anything two neutron stars can cook up from
>several hundred light years away.

It is speculated that half the Earth's biomass consists of single-cell
organisms living in the crust, to depths of several kilometers.
These critters would survive even nearby events, and might provide seed
stock for the next expansion and evolution of surface life. This kind
of life might be universal.