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