Still no word from ET

Mulder and Scully made it look so easy. An alien hunt has been underway for more than five years using the world's largest grid supercomputer - 5 million Internet-linked PCs - as part of a project called SETI@Home. The project, run by the University of California Berkeley, harnesses unused CPU cycles to comb through deep-space radio noise, searching for signals from extraterrestrials.

So after expending 2 million years of accumulated CPU time and analyzing 50T bytes of data - are we alone?

"We still don't know the answer to the big question," says Dan Wertheimer, chief scientist for the SETI@ Home project and the director of the Search for Extra Terrestrial Intelligence (SETI) program at UC Berkeley. "We haven't bugged any aliens yet."

But this wasn't a bummer to the world's top ET scientists, who congregated at Harvard University for last week's SETI Symposium. Dozens of astronomy Ph.D.s spent two days discussing strategies for detecting intelligent life in the universe.

"I'm optimistic that earthlings will find ETs in the long run," Wertheimer says, "But don't hold your breath."

With the one-in-a-billion odds of a SETI@Home PC finding an alien radio signal, many volunteers have turned the project into a kind of PC hot-rodding contest, where users soup up their machines in a race to produce the most work units - the chunks of radio waves distributed by SETI@Home to clients. The SETI@Home software also has become a tool for testing and benchmarking computer performance among IT professionals and some server vendors.

SETI@Home starts with Cornell University's Arecibo Observatory radio telescope in Puerto Rico - a dish three times the size of the new Olympic Stadium in Athens, Greece - which collects radio noise from distant stars. The data is recorded on tapes that are sent to Berkeley, where servers break them into chunks and make them available over the Internet. The 5 million PCs worldwide that have the SETI@Home screen-saver program installed can download chunks of signals and look for patterns in the noise. The processed work units are then sent back to Berkeley's SETI computer lab - a storage closet in the astronomy department where the servers are kept.

SETI@Home's Web site keeps a leader board for the top work-unit workhorses. Statistics show individual performances and SETI@Home groups, which include corporations such as Boeing, Sun, HP and Cisco, and organizations such as Ohio University, the University of Leeds in England and the Tempe, Ariz., Union High School District.

"It's hard to say whether the main motivation for people running the program has more to do with scientific goals or with the competition for work units," says David Anderson, director of the SETI@Home project, who wrote the screen-saver software. "The competitive aspect, having the fastest computer on the block, is probably the main driving force."

Anderson says the most enthusiastic users tweak their computers' CPUs to squeeze out every megahertz of performance for processing work units.