[meteorite-list] More evidence of building blocks of DNA in meteorites
From: GRAHAM, FRANCIS <fgraham_at_meteoritecentral.com>
Date: Wed, 10 Aug 2011 07:34:01 -0400
It is of course OK to be skeptical of claims of life elsewhere in the Universe. Carolus Linnaeus, the founder of biology, to avoid considering sailor tales (and later Bigfoot, Yeti, and Loch Ness claims) insisted on a type specimen. The controversy over ALH 84001 boils down to whether the truncated hexaoctahedral magnetite crystals found constitute a type specimen, or were they produced abiotically on Mars (they are not produced abiotically on Earth). It is always possible to posit by some Rube Goldberg-like mechanism am abiotic origin to almost any trace biological evidence. Insisting that evidence absolutely not have any abiotic orgin possible under any circumstances is a hurdle too high and in my view, too illogical. That is the difficulty.
Of possible use in this brouhaha is Rudolf Carnap's theory of logical probability assigned to theories. An accepted type specimen is of course, proof positive; the probability of extraterrestrial life then is 100%. But the probability is still nonzero that microscopic life indeed does exist under the frozen lake of Elysium. Assigning probability to a theory is a difficult task, and the popular media folks are totally clueless on the concept. IMVHO, the evidence is such that it is more probable microscopic life exists/existed on Mars that not.
But Carnap's ideas, endorsed by Martin Gardner, will be helpful in this situation. An outline of them is found in Carnap, R. Philosophical Foundations of Physics, Basic Books, London 1966. edited by Martin Gardner.
Kent State University
From: meteorite-list-bounces at meteoritecentral.com [meteorite-list-bounces at meteoritecentral.com] On Behalf Of dorifry [dorifry at embarqmail.com]
Sent: Tuesday, August 09, 2011 2:49 PM
To: meteorite-list at meteoritecentral.com
Subject: [meteorite-list] More evidence of building blocks of DNA in meteorites
Hello fellow Listerians:
It's hype, just like the sketchy arsenic-based life forms and the imaginary
Martian fossils. First off when you say DNA, most people think of a biotic
double helix just like we have in the nuclei of our cells. Components of
DNA is an entirely different thing, like maybe a little bit of a rung from
the DNA ladder. And the same nucleobases plus some hypoxanthine and xanthine
were found in the surrounding ice and soil samples near the other
meteorites. Sounds a lot like terrestrial contamination. Maybe the analog
compounds were present or created at impact, but it sure sounds like the
other stuff seeped in while the meteorites lay there for how long? I mean
c'mon the exact same compounds? What are the chances of that? They've got to
stop crying wolf all the time, it's getting old.
Joshua Tree Earth& Space Museum
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Received on Wed 10 Aug 2011 07:34:01 AM PDT