Astronomers reconsider how
extraterrestrials could make contact
The Earth is going silent. Digital television signals delivered by cable and satellite are quickly replacing analog broadcasts
and reducing the number and power
of radio waves leaking into space. For
viewers at home, it means more channels and pictures of unsurpassed clarity.
But for scientists seeking signs of
advanced civilizations beyond the solar
system, this sudden radio silence makes
the search fuzzier.
Since traditional searches for extraterrestrial intelligence, collectively
dubbed SETI, have assumed that the
path to intelligence proceeds similarly
throughout the galaxy, SETI researchers
are now wondering: If extraterrestrials
can’t hear us, how will we hear them?
Some serious rethinking may need to
be done. Much of the hunt for signals
from ET so far has been based on a fading fad— a century-long blip of radio
mania — rather than an enduring characteristic of galactic societies.
It’s not just television. Military radar,
once the prime outgoing evidence for
intelligence on Earth, now jumps from
channel to channel, to confuse enemies
trying to jam the signal. And the power
radiated by cell phones is spread across
more than a thousand channels, making the waves—to a planetary outsider — indistinguishable from noise.
“Our improving technology is caus-
ing the Earth to become less visible,”
says astronomer Frank Drake, SETI’s
paterfamilias. “If we are the model for
the universe, that is bad news.”
For SETI researchers, that bad news
comes after 50 years of no news. Since
Drake first turned a radio telescope to
the nearby stars Tau Ceti and Epsilon
Eridani in 1960, there have been no
signs of ET phoning Earth or phoning
home —or phoning any other intelli-
gence in the galaxy, for that matter.
“We have all seen our little bumps
in the night, but we have never had
repeated signals,” says Paul Horowitz of
In the past, failed SETI searches have
fueled further efforts. And now, even in
the face of the latest discouraging realiza-
stars: timoph/istockphoto, earth: Nasa/Goddard space FliGht ceNter, illustratioN: b. rakouskas