Why would you conclude, Darin, that ETI,s would use low-power signals and
avoid making their presence known? Why should they care, and why need they be
mindful of us, if they exist?
In a message dated Sun, 22 Oct 2000 1:34:31 PM Eastern Daylight Time, "Darin
Sunley" <email@example.com> writes:
<< From today's Winnipeg Free Press.
It's interesting to see these issues gradually percolate into the public
consciousness. Of course Mr. Dyer doesn't mention the most probable cause
(IMHO) of the silence, which is that the aliens are using very precisely
aimed low powered signals, compressed sufficiently to be indistinguishable
from thermal noise, even if we did happen to be in the line of sight of one
of them, which we probably aren't. Oh well :)
So many new planets, so few signs of life
Sun, Oct 22, 2000
"YOU can go outside at night, even in Austin, and point at it and say that
star there has a planet around it," said Dr William Cochran of the
University of Texas's Department of Astronomy. Epsilon Eridani, the star in
question, is not especially bright, but it is very close: that's why it's
visible to the naked eye. Nobody has found a star with planets that close to
us before -- but then, until 1995 nobody had found any stars with planets
orbiting them at all.
Then astronomers developed techniques for detecting planets (though only
very big ones) around other stars, and the flood-gates opened. In the past
five years, 40 new planets have been discovered, all gas giants on the same
scale as Jupiter, our own system's biggest planet. In August, at the
International Astronomical Union's 24th general assembly in Manchester,
England, another 10 have been revealed, including the planet found around
Epsilon Eridani by Cochran's team.
"It's a very exciting discovery," explained Dr. Geoff Marcy of the rival
planet-hunting team at the University of California Berkeley, "(because)
it's only 10 light years away. In the next 100 or 200 years, it will be one
of the first stars humans visit."
It begins to look like a universe where it is normal for a star to have a
family of planets. While existing techniques still cannot discern smaller,
rocky planets like our own around other stars, the Solar System's familiar
pattern of several gas giants in outer orbits and some smaller, more
habitable planets closer in to the warmth of the sun also seems more and
So if suitable planets are as common as dirt, and life is not rare but
commonplace on them -- then where is everybody?
The puzzle has been growing ever since the SETI (Search for
Extra-Terrestrial Intelligence) project was set up in the 1970s. Every
plausible frequency of the electromagnetic spectrum has been monitored more
or less continuously for signs of intelligent life-forms on other planets.
The result? Silence. Either there's nobody intelligent out there, or for
some reason they're not talking.
This raises three possibilities, each of which would have large implications
for our view of our own place in the universe.
One is that an intelligent species capable of producing high technology is
not a normal evolutionary outcome, but a freakish event. In that case, there
is a whole universe of friendly habitats with no intelligent natives out
there waiting for us, and the human race's far future could well resemble
the kind of "galactic empire" so beloved of early science fiction.
The second, darker possibility is that while intelligent life crops up
often, it doesn't last long: species that develop technology wipe themselves
out quite fast. That could explain the silence, for if the average survival
time of a high-tech civilization is only a few hundred years, then even if
there are tens of billions of suitable planets in our galaxy, there would on
average be only one civilization (or none) in existence at any given time.
The third, darkest possibility is that there are indeed lots of intelligent
species in the galaxy, but the smarter ones are keeping their heads down. If
you have no idea what's out there -- or if you know what's out there, and it
scares you half to death -- then the last thing you want to do is attract
attention by broadcasting your position across the cosmos.
A fanciful speculation, but then all three of these options seem quite
unlikely -- yet one of them must be true. Our ignorance about the universe
is still very great, and unless the human race wipes itself out, later
generations will probably lump us together with the Ottomans and the Tang
Chinese and the Roman empire as "dawn civilizations." But it is an
interesting time to be alive.
Gwynne Dyer is a London-based independent journalist. His column appears on
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