[escepticos] RV: EXTRATERRESTRIAL CIVILIZATIONS: COMING OF AGE IN THE MILKY WAY

["Eduardo Zotes Sarmiento" <diotalle@...>]

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Eduardo Zotes Sarmiento
C.G: Sociedad para el Desarrollo de la Actitud Cientifica
SDAC web: http://web.jet.es/diotalle/index.htm
Club del Ensayo: http://web.jet.es/diotalle/cde/index.html
email: < diotalle en jet.es >

-----Mensaje original-----
De: Cheryl Gundy <gundy en stsci.edu>
Para: pio en stsci.edu <pio en stsci.edu>
Fecha: viernes 11 de diciembre de 1998 2:41 AM
Asunto: EXTRATERRESTRIAL CIVILIZATIONS: COMING OF AGE IN THE MILKY WAY


>EMBARGOED UNTIL:  9 a.m. (EST) December 10, 1998
>
>CONTACT:  Ray Villard
>          Space Telescope Science Institute, Baltimore, MD
>          (Phone:  410-338-4514)
>
>          Mario Livio
>          Space Telescope Science Institute, Baltimore, MD
>          (Phone:  410-338-4439)
>
>
>PRESS RELEASE NO.:  STScI-PR98-43
>
>
>EXTRATERRESTRIAL CIVILIZATIONS: COMING OF AGE IN THE MILKY WAY
>
>If civilizations exist around other stars they are likely to be just
>emerging across our Galaxy right now: like an apple orchard suddenly
>maturing and ripening in the autumn sun.
>
>So concludes Space Telescope Science Institute theorist Mario Livio,
>in a paper to be published in the Astrophysical Journal.
>
>Livio emphasizes that his theoretical work doesn't necessarily mean
>extraterrestrial civilizations really do exist, but it shows they cannot
>be dismissed either.
>
>We would be a lonely, isolated quirk of cosmic evolution if intelligent
>life forms appear on a planet at some random time in the parent star's
>life, say some theorists.
>
>Instead, Livio makes the case for a possible causal link between the
>sun's lifetime and the appearance of intelligent life on earth. This
>link should hold true for sun-like stars elsewhere in the universe:
>offering an equal opportunity for intelligent life to arise elsewhere in
>space.
>
>The second part of his case is based on the possibility that carbon --
>the fundamental building block of life as we know it -- may not have
>been widely available until the universe was about 1/2 its present age.
>
>This means that, given the added billions of years more required for
>biological evolution, intelligent carbon-based life didn't make an
>appearance any earlier than roughly 3 billion years ago.
>
>He points out that before the universe could make life like us, it has
>to make carbon atoms. The carbon was created by nuclear fusion in the
>hearts of early stars, and then ejected when the stars lost their outer
>gas layers and left their cores behind as white dwarfs.
>
>Livio calculates that carbon production may have peaked only two billion
>years before the sun and earth formed, based on estimates of the star
>formation rate made with Hubble Telescope and other ground-based
>telescopes.
>
>Though life first emerged on earth a few hundred million years after
>its formation, it took a vastly longer time - nearly 3 billion years --
>for the first multi-celled organisms to appear. It took almost another
>billion years before life emerged from the sea onto the land.
>
>The earliest humans appeared less than 4 million years ago - at about
>the halfway point in our sun's lifetime. If this were purely
>coincidental, other theoreticians have argued, then it would take much
>longer than the life of a star for most civilizations to arise. And so
>it would be unlikely extraterrestrial civilization would come about at
>all. We would be alone in the universe: reduced to a novelty - or
>accident - of the cosmos.
>
>Because sunlight provides far more energy for life than other chemical
>processes, biological evolution is intimately linked to the sun's
>behavior, Livio maintains. For example, the complex evolution of our
>atmosphere is interrelated with the sun. Our planet's atmosphere had to
>develop ozone to block out destructive UV radiation from the sun before
>animals could emerge on the land
>
>Likewise, he says, other civilizations should have emerged not much
>sooner or later than about halfway through their parent star's life
>cycle.  That is, around stars like our sun, or slightly cooler, that
>live healthy long stable lives and release enough energy to nurture life
>on accompanying planets.
>
>If Livio is correct, and the Galaxy may be blooming with new
>civilizations, then where are they? Why haven't they visited us?
>
>Livio cautions that his work does not prove the existence of
>extraterrestrial civilizations, but points out that earlier conclusions
>that they do not exist may be premature.
>
>He says that that it's also risky to think civilizations would colonize
>the Galaxy. "This assumes we have even the vaguest understanding of the
>psychology of extraterrestrial civilizations."
>
>He adds: "It's impossible to imagine the thinking of a civilization
>which might have evolved a million of years ahead of humans. We could be
>about as uninteresting to them as an amoeba is to us. Actual proof will
>have to await advances in biology and astronomy."
>
>                          -END-
>
>The Space Telescope Science Institute is operated by the Association of
>Universities for Research in Astronomy, Inc. (AURA) for NASA, under
>contract with NASA's Goddard Space Flight Center, Greenbelt, MD.  The
>Hubble Space Telescope is a project of international cooperation between
>NASA and the European Space Agency (ESA).
>
>NOTE TO EDITORS:  This release is available on the Internet at:
>http://oposite.stsci.edu/pubinfo/1998/43 or via links in
>http://oposite.stsci.edu/pubinfo/latest.html
>
>STScI press releases and other information are available by sending an
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