ET may be out there, astronomer says

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The search for extraterrestrial intelligence is gaining speed so quickly that we could soon detect radio signals from other sentient species, said an astronomer who plays a key role in the hunt said."This isn't going to take centuries. It's going to happen within a generation" if intelligent life is as abundant as many scientists speculate, said Seth Shostak, a senior astronomer with the SETI Institute.In a breezy talk punctuated with a few graphs and a lot of shots of Hollywood aliens, Shostak ran through the possibilities for a Carmichael, Calif., audience gathered to celebrate "Darwin Day." An almost unimaginable number of stars are visible to our telescopes -- think of a 1 with 22 zeros after it. Many of those stars, perhaps most, are orbited by planets, and "planets are kind of like kittens. You don't just have one or two," Shostak said.In that panoply of planets, he said, it seems likely that some harbor intelligent life, although guesses about how many range from 10,000 to 1 million or more.The SETI Institute has established a simple criterion for evaluating whatever intelligence may be out there."If you can build a radio transmitter, you're intelligent," Shostak said, suggesting -- to some nervous laughter -- that his listeners might consider the same guideline for sizing up one another.Founded in 1984, scraping by on donations and using time on other people's telescopes, the SETI Institute sorts through the natural radio noise of the universe, seeking narrow-band signals produced only by transmitters.It is getting a huge boost this year, as the first phase of radio dishes for the Allen Telescope Array undergoes final testing at the Hat Creek Radio Observatory near Lassen National Park.Along with the vast improvement in listening capability, SETI also is benefiting from faster computer processing power, allowing the speed of its search to double roughly every 18 months.At that rate, we ought to be able to analyze enough of the sky to pick up a signal sometime between 2015 and 2025 if intelligent life forms are plentiful, Shostak said.Elsewhere, in response to criticism that SETI should consider other search techniques less focused on how humans communicate, he has suggested that if nothing is found by 2028, it could be time to try new strategies.Shostak speculated that any intelligence we do locate will be too far away to hurt us and might be machine-based.The search for life beyond our planet "has everything to do" with evolution, he said, fielding a question about one of the central themes of the Darwin Day celebration of science and scientific inquiry."I don't imagine that you're going to get thinking entities without Darwinian evolution," Shostak said.He spoke in connection with the 11th annual celebration of Darwin Day, one of hundreds of events held around the country to honor both science in general and Charles Darwin, famed naturalist who assembled evidence of natural selection.(Contact Carrie Peyton Dahlberg at cpeytondahlberg(at)sacbee.com)(Distributed by Scripps Howard News Service, www.scrippsnews.com.)