Re: starship-design: Fermi's Paradox - Drake's Equation will have to be rewritten

["Antonio C T Rocha" <arocha@zaz.com.br>]

-----Mensagem original-----
De: L. Clayton Parker <lparker@cacaphony.net>
Para: AJ & AJ Crowl <ajcrowlx2@ozemail.com>; Starship-Design
<starship-design@lists.uoregon.edu>
Data: Quinta-feira, 28 de Janeiro de 1999 22:51
Assunto: RE: starship-design: Fermi's Paradox - Drake's Equation will have
to be rewritten


>I would argue that it is next to impossible for ANY civilization to survive
>to the point where they could predict AND PREVENT a GRB in sufficient
>proximity to wipe them out. As a matter of fact (without really having
>looked at the math) I would bet simply surviving such an event is probably
a
>major feat, although probably not impossible. Does anybody know of a good
>gamma ray shield?
>
>Lee Parker

Err, a (string of) gas giants? :-)   [ ACR ]

>>
>> Consider when it might have happened last near enough to affect life on
>> Earth... ? Like when? I have a couple of suggestions - about two billion
>> years ago, quite close; and about 250 million, not so close. The first
>> relates to a study which dated the divergence of life from a
>> common ancestor
>> ~~ 2 billion years ago - that conflicts with every fossil from
>> prior to that
>> time. But what if a GRB had wiped out all but one species? The
>> other date is
>> the great Permian extinction, which wiped out most life on land and in
the
>> sea. It's been tied to a catastrophic overturn in the ocean that released
>> huge amounts of CO2. Earth at that time had one continent and a global
>> ocean. If the GRB hit the ocean side then life wouldn't notice it
>> much - but
>> what if that acted as trigger for the overturn? Some change in acidity or
>> greenhouse processes from massive amounts of upper atmospheric chemistry,
>> which changed the thermal balance of the ocean...
>
>> If anything is a strong argument for a galaxy-spanning civilisation it's
a
>> GRB - if you want to think in the long term and survive then GRBs
>> need your
>> attention. How do you stop them? By knowing how they form for starters.
No
>> one is still too sure.
>>
>