Re: Jurassic intelligence (time-scale for evolution of alien

[cnedin@geology.adelaide.edu.au (Chris Nedin)]

Mike Bonham wrote:

>Carl Sagan presented an argument that we may be alone, despite great odds
>of finding life in the galaxy, in his and Shklovskii's 1970's-ish book
>`Intelligent Life in the Universe'.
>
>Starting with the `Drake equation' where various conservatively-estimated
>probabilities are multiplied together (probability each star has planets,
>fraction of planets suitable for aqueous life, probability life actually
>arises, probability life becomes multicellular, probability intelligent
>species arise, probability technological civilization arises, fraction of
>the galaxy's lifetime thatcivilizations last...etc.  This gives a very
>small fractional probability that a star has detectable intelligent life,
>but then gets multiplied by the huge number of stars in the galaxy,
>yielding a number in the tens of thousands for the expected number of
>concurrently-existing technological civilizations.  We haven't (yet)
>noticed any of their effects on their stellar environment, intercepted
>their communication signals, etc.
>
>Moreover (!), if any single one of them decided space exploration and
>colonization was a GOOD IDEA (TM), it would only take a couple of hundred
>thousand years at sub-light speeds achievable by presently-envisioned
>rocket technology, to spread to all habitable star systems in the galaxy.
>They're not here (side-stepping the UFO enthusiast's protestations that
>they ARE here!)

>If intelligent dinos lived, couldn't they have been like the other
>galactic minds and been undetectable? :-)

Maybe they foresaw which way the planet was heading (all those pesky
mammals underfoot) and left.

The crater in Mexico is in fact the *launching* site not an impact site!

Chris

cnedin@geology.adelaide.edu.au,   nedin@ediacara.org
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Many say it was a mistake to come down from the trees, some say
the move out of the oceans was a bad idea. Me, I say the stiffening
of the notochord in the Cambrian was where it all went wrong,
it was all downhill from there.