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- NEW YORK - The other day, Ross Schaack's computer detected
something unusual.
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- So, while Schaack was away at work, the
computer dialed a connection to the Web and reported its data to a main
computer in Berkeley, California. Days later, Schaack's user name appeared
in a top ten list for detecting one of the most interesting finds of the
month.
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- [Photo: High peaks in SETI's program
indicate strong signals while a counter above records long, unusual radio
signals]
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- Schaack, meanwhile, was oblivious that
his computer had picked up what appeared to be an alien signal.
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- "I was surprised," said Schaack,
a mechanical engineer in Forest, Virginia. "I just checked the SETI@home
site and I see that I have several entries!"
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- Schaack's PC isn't particularly special,
in fact, its capabilities are on par with many personal computers. But,
by employing a free screen saver program offered by the alien-searching
organization, the Search for Extraterrestrial Intelligence, it is equipped
to sort through data from the world's largest radio telescope and look
for unusually loud, long, or pulsing alien-like signals.
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- Currently, more than 660,000 computers
are tapped into SETI's at home network. In the program's first month, its
team of "volunteer" computers devoted a total of more than 15,000
years of time toward analyzing sounds from space. Together, they make up
the most powerful computer in the world.
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- "We thought we'd maybe get 100,000
people," said Dan Werthimer, chief scientist of the program. "Now
we're getting 20,000 new people a day. I expect we'll get to a million."
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- In fact, interest in the program has
been so high, that the ever expanding network of computers has, at times,
overwhelmed its creators.
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- At one point, the system became so confused
that it began sending the same units of raw frequencies to participants
over and over. Meanwhile, hackers have broken their way into the system's
top users list " a ranking of those who have devoted the most computer
time to alien searching. SETI's project director, David Anderson, estimated
that at least two of the computer users appearing in the top 10 list reached
their rankings by cheating.
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- Hackers may find temporary glory in the
top users list, but Werthimer says the most exciting statistics are those
that list detections like Schaack's discovery. While strong signals usually
emanate from a satellite or other earthly origins, long signals with a
curved shape indicate something more interesting.
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- "As the telescope moves over something,
you'd expect it to get strong. Then as it moves away, it should get weaker,"
explained Werthimer.
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- [Photo: SETI Institute: The radio telescope
in Arecibo, Puerto Rico sends data to Berkeley computers, where it is forwarded
in bite-size chunks to PCs]
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- The SETI screen saver program identifies
these long, curved signals under a counter labeled "top gaussians."
A green "top gaussian" light indicates something slightly alien-like.
A yellow light is, in Werthimer's words, "somewhat interesting"
and a red light is "really exciting."
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- The SETI program is one of a growing
number of so-called distributed computer programs designed to harness the
millions of hours that personal computers spend idle. Rather than spending
spare hours running useless screen saver programs, computers hooked up
to a distributed computer program may spend their time cracking codes or
mathematical problems " or looking for unusual blips in radio signals
from space.
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- But in SETI's distributed computer program,
there is no such thing as instant discovery. Werthimer warns there are
many steps to analyzing any unit of space sound. Once data reaches the
main computer at Berkeley, it is merged with other data. Here, the computer
eliminates noise from interfering satellites and test signals and searches
the information for interesting patterns.
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- The chances that a personal computer
will actually pick up a slice of sound containing an alien signal are discouragingly
slim. Each unit of data that a SETI@home computer processes represents
a mere 107 seconds from one millionth of the night sky. That means if there
is alien life that can be detected, a user has only a one in a million
chance of actually picking up a piece of that noise.
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- "Right now, Earthlings are just
scratching the surface," he said. "We're only covering a very
small band in the microwave spectrum."
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- In fact, when users sign up to use the
SETI@home screen saver, they must promise to temper their excitement in
a waiver that reads "I will not get alarmed and call the press when
[strong] signals appear."
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- Schaack certainly posed no danger as
an alarmist since it was, after all, a member of the press who alerted
him to the work of his computer. That's just as well since the signal his
computer detected, turned out to be nothing remarkable. Others, meanwhile,
don't even carry the slightest expectations that their computers will actually
zero in on an alien noise.
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- "I really don't think my computers
will ever find anything," said Lothar Krause, a software engineer
who installed the SETI program on both his home and work computers. "But
it's still a great experiment in combining computers to solve a common
problem."
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- The SETI@home program is scheduled to
run for two years. After that, Werthimer hopes to update the program so
it will search a broader range of frequencies for signs of distant life.
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