From: frank@Cookie.secapl.com (Frank Adams)
Subject: Re: Question about SETI:summary & response
Date: Wed, 11 Nov 1992 21:52:03 GMT
Organization: Security APL, Inc.

In article <1992Nov8.105016.44517@kuhub.cc.ukans.edu> miner@kuhub.cc.ukans.edu writes:
>ORIGINAL QUERY by MINER:
>     Search for Estra-Terrestrial Intelligence has recently been
>greatly enhanced; in coming years even newer technological resources
>can and surely will be applied to it (it seems fairly low-cost as
>research goes).
>
>     I'd like to get some reactions to the following question (I
>will summarize results):
>
>     If, after a considerable period of time, say twenty more
>years, has been devoted to SETI, and still we have no reliable
>indication that intelligent life exists elsewhere in the universe, do
>you think this would have any effect on your personal philosophical
>outlook, and if so, what effect?  
>
>     And if not, do you therefore consider SETI philosophically
>irrelevant?

I don't expect SETI to actually find any ETI.  The fundamental question
which SETI enthusiasts fail to address adequately is, if there are lots of
intelligences out there, why aren't they here?

I do not think it is at all plausible to maintain that interstellar travel
is impossible.  There are technologies now under development which will
enable travel at about 0.1c.  Given the number of possible technologies for
high speed travel which we know of already, it is extremely unlikely that
none of them will ever work out.

It does not work to maintain that there may be lots of civilizations in the
galaxy that have developed space-flight technology, just not of them have
gotten here yet.  The time scales are wrong -- technological civilization is
built on a time-scale of centuries, interstellar travel at a conservative
0.1c takes decades to reach nearby stars, and about a million years to fill
the galaxy.  But the age of the galaxy is measured in *billions* of years.
It would take an incredible coincidence for us to be close enough to the
first.

It is sometimes argued that interstellar travel would not happen, because
there is no reason for it.  Much the same argument could be made for
colonizing the New World when it was discovered -- and, indeed, only a tiny
fraction of the human race relocated.  But it doesn't take lots --
essentially, *any* suffices.  The same kind of uniformitarian assumptions
which are used to conclude that ETI must be common imply that we are not
extraordinary in our psychology.  And evolutionary considerations suggest
that any intelligent race is like to have some imperative to spread out.

The same objection applies to the question, "why should they come *here*, in
particular?".  They wouldn't come here in particular; they would go
everywhere.  What parts of the Earth have we not gone to?  Maybe they don't
Earth hospitable, but that hasn't kept *us* from visiting and leaving
artifacts everywhere we could get to -- and I expect any star-faring race
would be able to deal with the problems of visiting Earth.

The problem of time-scales also mitigates against the proposal that they
might be keeping Earth as some sort of sanctuary -- perhaps as part of a
policy of protecting all worlds with indiginous life.  The problem is that
social structures change on a time scale of centuries; to maintain a
consistent policy over billions of years would be incredible.

---------------

This argument is essentially due to Fermi; combined with the arguments *for*
ETI, it is known as Fermi's paradox.  It bothers me the way people who
should know better (like Carl Sagan) repeat the arguments *for* ETI, and
ignore the arguments against.  It leads to a large group of people who know
only the arguments for, and are surprized to find reasonable people on the
other side.

---------------

My own best guess is that advanced life-forms are not common, that we are
the only intelligent species in the galaxy, if not the local group of
galaxies.  There are two candidate events which, based on current
understanding, could well have be very unlikely:

(1) the development of life at all

(2) the development of the modern cell

For (1) to be plausible, one must assume that life could only have happened
early in the history of the planet.  Otherwise, it *did* happen too early
for the assumption that it is very unlikely to be plausible.  (*None* of
these possibilities are really *impossible*; this is a judgement of relative
likelihood.)

The modern (I think the word is "euchariotic") is believed to have only
evolved after a couple of billion years, and it may well have been a very
unlikely event.
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