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From: KFL@AI.AI.MIT.EDU ("Keith F. Lynch")
Newsgroups: net.space
Subject: Aliens
Message-ID: <[AI.AI.MIT.EDU].22227.860328.KFL>
Date: Fri, 28-Mar-86 22:18:24 EST
Article-I.D.: <[AI.AI.MIT.EDU].22227.860328.KFL>
Posted: Fri Mar 28 22:18:24 1986
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    From: hplabs!qantel!ptsfa!gilbbs!mc68020@ucbvax.berkeley.edu  (Tom Keller)

       Presumably, either they would have detected our emissions, and started
    on an exploratory expedition sometime in the past 100 years or so, or we
    would be detecting their emissions.

  Not necessarily.  They may not use the radio spectrum at all, either
because they have found a different spectrum or because they use
fiberoptics or cables for communications.  They may use only tight
beams for interplanetary communications.  Or they may use light or
some other part of the EM spectrum.
  Even if they generate as much radio as Earth, we could not detect
that if they were more than ten or twenty light years away, unless
they were deliberately aiming a strong signal in our direction.
  Why would they come exploring if they knew of us?  Maybe they aren't
interested.  Or maybe they ARE closely observing us without announcing
themselves.  Or maybe they are on their way and will land next week.
  I don't think any of us are competent to say what their technology
would be capable of, any more than Aristotle could have said anything
reasonable about what computers or the Space Shuttle can do today.
Neither can we do more than guess at their motivations, i.e. whether
they would come here at once if they knew of us.
								...Keith