Today, a science-fiction question gets a scientific
answer. The University of Houston's College of
Engineering presents this series about the machines
that make our civilization run, and the people
whose ingenuity created them.
Everyone who's ever spent
time on a campus has eventually run into a
marvelous piece of graffiti. It says, "Beam me up
Scotty, there's no intelligent life down here."
Students have always questioned the intelligence of
life on their campuses. But we want to ask about
intelligent life on other planets.
In 1960 we moved from speculation about life on
other worlds to a scientific search for it. We
began using radio telescopes to listen for signals
from other planets. By now we've listened at 50
sites for well over a hundred thousand hours. Most
of the work has been government-funded; but when
the Harvard listening project ran low on funds,
Steven Spielberg came to its rescue. No one's heard
anything yet, and we might wonder if it's all a
fool's game. Do we really have reason to expect a
close encounter of any kind?
The rationale for expecting to find other
intelligent civilizations was summarized by I.S.
Shklovskii and Carl Sagan in 1966. It goes like
this: We know the number of stars within radio
telescope range. Some have habitable planets. Life
will arise on some of those, and a few will reach
technological intelligence. When such civilizations
arise, they'll last for a certain time -- but how
long? Shklovskii and Sagan estimated these numbers.
Then they used the laws of probability to show that
a million intelligent species should be within
reach of our radar.
But the phone hasn't rung yet. Maybe Shklovskii and
Sagan were overoptimistic. As we fail to hear
signals, we revise their estimates downward, and we
settle in for a long wait.
Scientists speculate on at least two reasons for
silence from outer space. One's the so-called "Zoo
Hypothesis." It says that our civilization is very
young -- that others are way ahead of us. Far from
racing to communicate, the more advanced races seal
us off and watch us like animals in a zoo. The
other idea is that evolution itself required far
more luck -- or even miracle -- than we realize.
Perhaps the evolution of intelligent life is such a
remarkable miracle of nature that we are, in fact,
a unique species after all.
In the end, the research hasn't given us
independent answers to philosophical and religious
questions about our uniqueness as a species. But it
has led to improved radio telescopy. It's made us
learn more about the nature of planetary radiation
fields and about the nature of humankind. The
search itself is both humbling and exciting. In the
end, we're not just listening -- we're thinking at
the same time, and that's what makes the search
worthwhile.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
