Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site utastro.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!genrad!decvax!mcnc!akgua!sdcsvax!sdcrdcf!hplabs!hao!seismo!ut-sally!utastro!ethan
From: ethan@utastro.UUCP (Ethan Vishniac)
Newsgroups: net.origins
Subject: thermodynamics again
Message-ID: <480@utastro.UUCP>
Date: Tue, 4-Sep-84 11:34:55 EDT
Article-I.D.: utastro.480
Posted: Tue Sep  4 11:34:55 1984
Date-Received: Tue, 25-Sep-84 00:45:46 EDT
Distribution: net
Organization: UTexas Astronomy Dept., Austin, Texas
Lines: 25

{Herewith a sacrifice to the line-eater}

     Just a brief addendum to my last contribution.  There are
some organisms that seem not to use the sun as their ultimate energy
source.  The biological communities that surround undersea vents
are using the energy from the core of the Earth as a source and
the surrounding sea as a waste heat sink.  Since the core of
the Earth is kept hot by radioactive decay this makes them the
only examples of terrestrial communities entirely supported by nuclear
fission :-).
     It's interesting to speculate on whether this energy source alone
is enough not only to support life, but to provide a suitable environment
for its origin.  Probably the only test case we have available is
Europa ( a moon of Jupiter) which may have a rocky core heated by tidal
stresses and is capped by a surface of relatively smooth ice ( which 
argues for continual remelting and refreezing).  I think Arthur C. Clarke
uses it as the habitation of various strange organisms supported by
undersea vents in 2010 (for all you sf fans).

                         
"Cute signoffs are for     Ethan Vishniac
         perverts"         {charm,ut-sally,ut-ngp,noao}!utastro!ethan
                           Department of Astronomy
                           University of Texas
                           Austin, Texas 78712