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Alan Alda in Scientific American Frontiers

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Scanning the Dial

  The 85-foot telescope at the National Radio Astronomy Observatory was used by Frank Drake in Project Ozma

The Search for Extraterrestrial Intelligence, or SETI, began on April 8, 1960, when Frank Drake eavesdropped on radio signals from two nearby, sun-like stars. Though his historic search yielded nothing, Project Ozma inspired similar "listening" projects around the world.

Though Congress cut all public funding for SETI research in 1993, privately funded efforts continue. The long-running project SERENDIP (Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations) is underway at the Arecibo Observatory in Puerto Rico.

Covering 20 acres, Arecibo has the world's most sensitive radio telescope  

There, the 1,000 foot-wide radio telescope gathers huge amounts of astronomical data, which SERENDIP scientists then analyze for signals from an alien civilization. The problem is processing. No single computer can handle all the information, so Berkeley scientists Dan Werthimer and David Anderson came up with a way to get several million computers into the act.

  SETI@home participants help sort the huge amounts of data collected by SERENDIP

Werthimer designed software that allows personal computer owners to dedicate their machines' spare time to the search for a signal. The software behaves like a screensaver, allowing users to work undisturbed. But, during coffee breaks or over night, it downloads chunks of data from Arecibo and puts the computers to work.

As of July, 2000, more than two million computers in 224 countries were running the software. Since the project began on May 16, 1999, the combined processing time of participants totals more than 330,000 years. And in the last year, the project has turned up about 100 intriguing radio transmissions that merited a second look.

"So far, everything has turned out to be terrestrial interference," says Werthimer. "We think the universe is teeming with life, but there's still no evidence."

Werthimer remains optimistic. The SETI@Home project saves scientists the effort of building a new supercomputer every five years or so. Each SETI@Home volunteer who upgrades his or her personal computer is upgrading the entire project, little by little. Werthimer thinks computing power will have to increase by a factor of about a billion before we find what we're looking for. But with processing speeds doubling every year and with 3,000 volunteers signing up each day, Werthimer estimates they'll hit pay dirt in about thirty years. Not long in the context of human history.

"Humans are just new in the game," says Werthimer. "We've only looked at one corner of the Universe."

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Photos: David Parker, courtesy NAIC-Arecibo Observatory; NRAO/AUI; UC Berkeley

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