Universe Wide Web

BERKELEY —  Alive today is the first generation of scientists to interrogate the darkness. Conceivably it might also be the last generation before contact is made--and this the last moment before we discover that someone in the darkness is calling out to us.

--Carl Sagan [from “Pale Blue Dot,” p. 352]

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Every day, every few seconds, some of the world’s most powerful radio telescopes scan millions of channels in outer space in an effort to detect signs of extraterrestrial communication. No alien signals have been detected thus far. But is that because no one is out there contacting us, or are we just not listening hard enough?

Scientists are coming closer to the answer as legions of computer users around the world donate their PCs’ otherwise idle time to help in the Search for Extraterrestrial Intelligence, or SETI. Scientists at UC Berkeley’s Space Sciences Laboratory have been running the project, called SETI@home, for three months, in an ambitious hunt for signs of alien civilizations.

Earlier this week, the project passed a milestone by logging in its millionth participant.

“There are very few science projects out there that you can be a part of,” said Dan Werthimer, chief scientist for SETI@home. “This is the first program where people can participate in a global science project. It’s also a great way to get kids interested in science.”

And for those seeking long shots at fame, credit will be given to the person whose computer detects a signal that is verified as extraterrestrial.

“In this case, the odds are rather slimmer than winning the California lottery,” said Edna DeVore, director of education programs for the SETI Institute, which is independent from the research in SETI@home. “But I think that the real excitement this generates for interested persons is they feel like they can make a contribution to SETI search. That’s got a lot of charm to it.”

David Gedye, a former computer science student at UC Berkeley, conceived the idea of enlisting the help of thousands of Internet users in 1995. The concept was attractive in its simplicity, and in its relatively low cost, an important element since Congress cut off all funding to SETI projects in 1993.

Almost anyone with a PC and access to the Internet can download the free screen saver software from the project’s Web site at https://setiathome.ssl.berkeley.edu. Since the software became widely available on May 17, users in 224 countries have joined in the search, and the list is growing every day. Werthimer said the large number of users and the positive comments that have flooded in since the project began reflect the broad appeal of SETI@home.

“This is something people can immediately grasp,” said Werthimer, who hangs a flag symbolizing Earth next to his desk. “We all look up at the stars and wonder. You don’t have to be a scientist to do that.”

By harnessing the power of hundreds of thousands of computers, more radio signals can be analyzed more thoroughly than by any one supercomputer alone. Werthimer said the new computer program not only finds signals 10 times weaker than existing programs, but is able to distinguish a wider variety of patterns, such as pulsing or repeating signals, that were previously undetectable.

SETI@home takes recordings from the world’s largest radio telescope, located in Arecibo, Puerto Rico. The scientists are concentrating on signals from 50 million channels in a band centering on 1420 MHz, the frequency emitted by hydrogen. Werthimer explained that since hydrogen is the most abundant element in the universe, its frequency was chosen as a likely candidate for a communications channel.

The mounds of data are broken up into manageable chunks of 107 seconds, which then get distributed to the participants through the Internet. Each home computer receives a different set of data. The SETI@home screen saver program analyzes the data when the computer is otherwise inactive.

The analysis can take up to 24 hours on a 233 MHz computer. Computer users can keep track of the progress through colored charts and graphs displayed on the screen.

When the analysis is complete, the results are sent back to a home server to be replaced by a new chunk of data the next time the computer is online.

David Anderson, project director for SETI@home, said this divide-and-conquer approach to problem solving enables a level of unprecedented efficiency in radio astronomy. “We are logging in 1,000 years of computing time all in one day, which is kind of mind-boggling if you think about it,” he said.

But seeking signs of alien life is a task requiring patience of immense proportions. Radio astronomers are often resigned to the likelihood that they may spend years, decades, even a lifetime in the field without ever detecting signs of an extraterrestrial civilization.

“The odds are overwhelming that we will not hear a signal in this particular project,” Anderson said. “The project will be successful if we get a lot of people to use the thing for the full two years to search a big part of the sky thoroughly. It’ll be beyond our wildest fantasies if we do find a signal.”

Others say the lack of signals is an equally important result. “There’s one thing that people don’t concentrate on, and that is the power of a negative result,” said Louis Friedman, executive director of the Planetary Society, which provided early seed money for SETI@home. “What if there are very few, or no civilizations? That’s a profound result. That would influence greatly our understanding of life on Earth and of the origin of life.”

For enthusiasts of the quest, the belief that contact will be made cannot be dampened easily. Astronomers frequently point out that our sun is only one of more than 400 billion stars in the Milky Way galaxy, and our galaxy is only one of billions in the universe.

“I just can’t imagine in this huge, wild universe of ours, that we should be the only beings,” said Judi Cohen, a real estate lawyer in Oakland. Cohen joined in the program while it was still in its test phase. She said she would not be disappointed if her computer yielded no earth-shattering discoveries. But she hastens to add that she believes somebody will make contact with extraterrestrial intelligence before long.

“I just don’t know if I’ll be alive to know them.”