"Paul Bramscher" <brams006_nospam@tc.umn.edu> wrote in
message news:cict1o$964$1@lenny.tc.umn.edu...

Martin 53N 1W wrote:

Paul Bramscher wrote:
[...]

So if there was some chemical marker in the cosmos

which allow us to

find advanced organisms directly (not indirectly, via

technological or

chemical markers of behavior) we might open up a whole

new aspect to

SETI.  Would be nice to have a hypothetical "DNA

telescope."

Or just look for spectrographic smog (artificial

pollution).

Again, though, that's a chemical marker of behavior (which

has been

suggested too, and I hope it holds some promise).

But I'm wondering about directly detecting DNA or some

other molecule of

sufficient complexity to play host to an intelligent

organism, brain

waves, etc.  Some direct evidence, without behavior

dependencies.

Impossible currently, but who knows what the future may

hold...  The

problem is that without engineering or large-scale

environmental change

(environment including atmosphere, noise on the

electromagnetic

spectrum, etc.) intelligence by itself doesn't seem

detectable over any

great distance at all.

So it may be that larger clusters of intelligence (large

cities) will be

one of the earlier potentially remote-sensible artifacts

of

intelligence.  For example, cities might be approached as

(often, in

today's modern sense) having some signature (chemical,

albedo,

geometric, etc.) which make them often stand out.

We may never be able to pick out an alien's brain waves,

but we just

might detect a city on an earthlike planet in the next

century or two...

The sci-fi author, Jack McDevitt, in his series of novels
beginning with "Engines of God", posits that straight lines
and right angles of observed planetary artifacts are a
universal  indicator of cities (or alternative living
spaces) and may be used by alien agencies to ID intelligent
civilizations (a major plot point in the series.)
However, as you say, this is a fairly local technique also.
BTW, this is an interesting series of novels--good
action-adventure space opera, but with an exo-archeological
flavor and a cosmic stage of unknown "nemesis" factors...the
series answers Fermi with the conclusion that the galaxy at
any given time is only sparsely inhabited by ETIs, if at
all, with rather short lifetimes on the stellar scale--the
books give at least one good specific reason for this. :))
...tonyC