X-Message-Number: 11204
Date: Sun, 31 Jan 1999 12:13:58 -0800
From: Olaf Henny <>
Subject: Anybody Out There?

One of our CI directors, Dr. Michael Hart, was co-editor and contributor to
the book EXTRA-TERRESTRIALS: WHERE ARE THEY? published by 
Pergamon in 1982.His calculations indicated that, based on studies of 
atmospheric evolution, the chance of  life developing on a habitable planet 
is only around 10^ -30.

My opinion based on no subject knowledge and no idea of the
multitude of factors involved and no clue on how to even start
calculating the probability of the life developing event is that
the ratio should be higher by a whole bunch of orders of
magnitude.  Period. - So There! :-)

I am paraphrasing the words of an astronomer (I believe it was
Carl Sagan), since I do not remember them exactly: "To think,
that there are other civilizations out there is absolutely
awesome.  To think that there is no other civilization out there
with hundreds of billions of star systems in each of hundreds of
billions of galaxies is even more awesome."

Thoughts on the question: Then why haven't we met them yet?

It is a big arena out there.
The last cosmic event, which destroyed much of the life on earth
and which had the potential to destroy a civilization happened
about 65 million years ago.  Not much data to base estimates on
but let us assume, that the recurrence of an event of such
magnitude out here in the outer arm of the galaxy is 50 to 100
million years.  Let us also look at our nearest neighbor the
Centauri system: Binary, two suns creating a whole lot of
gravitational turbulence, probably enough to rip any emerging
atmosphere from a planet positioned close enough to either sun to
develop life. The erratic orbits in such a system would surely
result in climatic fluctuations too extreme to permit water based
life to emerge. That system is closest to us, but still 4.5 light
years away.  

If we go toward the center of the galaxy, cosmic turbulence is
much greater due to proximity of interfering solar systems as
well as increased interstellar debris, so that life ending cosmic
events are likely occurring on much too great a frequency to
permit civilization to emerge.

So back to the outer arm, where interstellar distances allow
relatively peaceful development of life, but the distances are
enormous.  Now we need a sun with just the right type of
radiation and a planet of proper size and positioning to develop
life recognizable to us.  Although there may be hundreds even 
thousands of those, the nearest one is probably hundreds of light
years from us and we have only made ourselves known in a rather
feeble way with electronic signals for about 100 years ago. And 
who knows given the turbulences other systems may encounter, we 
may well be one of the first few (-hundred?) civilizations out of 
the starting gate.

Our galaxy is enormous and sounding off for about a hundred 
years with a few feeble beeps, which have to penetrate the
interferences in the body of our galaxy to get to other sections 
of the galactic outer rim, may well get lost in its vastness.

Best, 
Olaf

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