[ExI] Panbiogenesis

[spike]

-----Original Message-----
From: extropy-chat-bounces at lists.extropy.org
[mailto:extropy-chat-bounces at lists.extropy.org] On Behalf Of Keith Henson
...
> Life on the night side at the time of the supernova might have a 
> chance against everything except the neutrinos, which would pass 
> through the planet and zap everything, regardless of the size of the 
> planet.  I'm pretty sure a supernova sterilizes everything in the stellar
neighborhood.

>...Three tenths of a light year is ~20,000 AU.  The energy dumped in a kg
of material at 1 AU would be 400 M times as that of at 0.3 light year, or
around 40 B j/kg or around 20 M kWh/kg, or something around a million times
the energy released in the formation of of the earth.
The reasonable assumption is that a planet at earth's distance from a
supernova would blow up spectacularly from the neutrino flux, if it were not
totally eclipsed by the supernova glare.  Keith

OK ja, those numbers are ringing a bell from a long time ago when I did some
BOTECs on this.  Supernova neutrino flux is really bad news for life forms
as we know it, because it causes one out of every jillion protons to absorb
a neutrino and (somehow) grabs an electron to become a neutron.  Then if it
is part of a carbon nucleus (plenty of those in every life form that we
know) that carbon becomes a boron atom with a half-life of about .02
seconds.  Most of those decays revert back to carbon 12, but a few of them
screw up the works as I vaguely recall for a long time ago.  If that life
form manages to survive the heating, the biochemistry is screwed up by the
neutrino flux.

As I also vaguely recall there is on the order of a thousand stars within
that lethal range, 30 to 50 light years.  Fortunately none of them are
candidates for that kind of supernova.

spike