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From: Susser.pasa@Xerox.ARPA
Newsgroups: net.sf-lovers
Subject: The Great Silence
Message-ID: <2944@topaz.ARPA>
Date: Fri, 26-Jul-85 17:08:02 EDT
Article-I.D.: topaz.2944
Posted: Fri Jul 26 17:08:02 1985
Date-Received: Sun, 28-Jul-85 07:56:00 EDT
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Organization: Rutgers Univ., New Brunswick, N.J.
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From: Josh Susser <Susser.pasa@Xerox.ARPA>

All this talk about why aliens would come to Earth raises a pretty big
question:  Why haven't any aliens contacted Earth?  I know there's a lot
of "evidence" that Earth has had visitors, currently and in the past,
but this is far from conclusive.  To all appearances, we are alone in a
galaxy that should be teeming with life and sentience.  And so, we are
left with the mystery of what has come to be called The Great Silence.

Those of you who read "Analog" know that David Brin has a semi-regular
column on science-fact and conjecture.  Recently, he has done a few
pieces on the question of The Great Silence.  I only caught his most
recent one, entitled "Just How Dangerous Is The Galaxy?"  In this essay,
Brin reviewed a number of hypotheses that could explain The Great
Silence.  In his previous column, he had asked for input from his
readers responding to the above big question.  In "Just How Dangerous Is
The Galaxy?" he presented the responses, along with arguments for or
against these hypotheses.

For those of you who are interested in this topic, I reccommend Brin's
column.  The essa is to long to summarize here, but I will present (in
no particular order) some of Brin's hypotheses for an explanation of The
Great Silence.

  1) We are truly alone.
  2) Sentient live is just appearing in the galaxy, and
     there are no civilizations significantly more advanced
     than we are.
  3) There is a galactic interdict prohibiting contact with
     immature civilizations.
  4) We are fundamentally different from other sentients, and
     thus have little chance of contact.  For example, we might
     not be noticed by beings who lived on gas giants or were
     ethereal energy blobs.
  5) Interstellar travel and communication are impossible.
  6) Berserkers or other hostile galactics are killing off our
     frindly neighbors.
  7) Civilizations with the agressive tendencies necessary to
     drive one to interstellar expansion kill themselves off
     before they mature (cf. Nucear Winter), and the surviving
     galactics are mellow enough to expand slowly, so they just
     haven't found us yet.

The tone of Brin's essay was rather depressing, and had me feeling that
we really are alone in the galaxy.  But, realizing this, Brin stuck in
his own pet hypothesis:

  8) Most habitable worlds are water worlds, so most other
     galactic sentients would be aquatic and incapable of
     building spacecraft.

I haven't presented Brin's arguments for the above hypotheses; I would
like to leave that for the net to discuss.  I would also be interested
in hearing any other hypotheses that could explain the mystery of The
Great Silence.

-- Josh Susser
   <Susser.pasa@Xerox.arpa>

...to boldly split infinitives no man has split before...