Will We Meet E.T.?

By Frederic Golden

We've come a long way since 1600, when Giordano Bruno, a defrocked priest from Naples, was burned at the stake for espousing, among other things, his belief that there might be other worlds and other life-forms beyond Earth. In our Star Trekking age, it's now almost heretical not to believe in extraterrestrial life--a belief that will surely be fortified by last week's announcement of the discovery of two Saturn-size planets around two distant stars.

Polls show that 54% of Americans are convinced that there are aliens out there, to say nothing of the significant fraction (30%) who suspect we've already been visited by them.

If there really is life elsewhere in the universe, what are the odds of finding it in our lifetime--or even our children's? Hunting for extraterrestrials, smart or otherwise, requires a lot of faith. You have to believe that conditions for life (liquid water, mild temperatures, protection from lethal radiation) are not unique to Earth; that under the right circumstances, life can arise fairly easily; and that if it does reach a level advanced enough to broadcast its presence, it won't destroy itself in a nuclear war or an environmental meltdown before firing off Earth-bound communiques.

That's plenty of ifs for skeptical scientists to swallow. As physicist Enrico Fermi liked to say, if there are so many extraterrestrials out there, why haven't we heard from them?

To some curmudgeonly types, all this E.T. talk is pretty brainless. Evolutionary biologist Ernst Mayr, for one, considers the likelihood of life of any sort beyond our planet close to zilch. Says he: "The chance that this improbable phenomenon [the creation of life] could have occurred several times is exceedingly small, no matter how many millions of planets in the universe."

Paleontologist Peter Ward and astronomer Donald Brownlee agree. In a provocative new book, Rare Earth, they maintain that in most places beyond Earth, radiation and heat levels are so high, life-friendly planets so scarce and the cosmic bombardments--like the one that killed off the dinosaurs 65 million years ago--so severe that the only life-forms that might make it would be bacteria-like critters living deep in the soil. The odds against technologically advanced societies, they argue, are astronomical.

Surprisingly, even Geoff Marcy, the leader in the increasingly successful hunt for planets outside our solar system, feels that we may well be alone in the universe. Most of the 33 newly discovered planets--giant gas bags all, including those two new ones--swing so erratically around their parent stars that they would create havoc on any smaller, nearby, life-friendly planets.

But such pessimism represents a minority view among scientists, at least those with their eyes on the stars. "In this business, you have to remain optimistic," says radio astronomer Frank Drake, who kicked off the original Search for Extraterrestrial Intelligence (SETI) in 1960 with his whimsically named Project Ozma (after the satiric Oz books). He "looked" briefly at several nearby sunlike stars in the hope that they might be orbited by planets whose inhabitants were sending out intelligible signals, like the flood of radio and TV broadcasts we've been inadvertently blasting into space for the past 80 years. ("Hey there, Alpha Centauri! Whaddya think of The Honeymooners?")

Drake, alas, detected nary a peep. Nor has anyone else since then. Even after spending thousands of hours scanning the skies, at myriad frequencies, at a cost of more than $100 million astronomers have yet to detect a single credible signal, though the most distant star probed is barely 1% of the way across the galaxy.

Still, Drake, 70, who devised the definitive equation for calculating the possible number of technologically advanced civilizations in our Milky Way galaxy, remains convinced that he will be around when one of them calls. "We're just at the beginning of our search," says Drake, who reckons that there are some 10,000 high-tech worlds scattered among the Milky Way's 100 billion or more stars. That's a much more modest figure than the late Carl Sagan's estimate of 1 million intelligent civilizations in just our galaxy--one of perhaps 100 billion galaxies scattered through the universe.

For years Congress funded various SETI efforts--until the political stigma of paying for the quest for "little green men," as cynics like to call them, scuttled federal funding in 1993. Nonetheless, NASA continues the search for unearthly life, even if it's only for little green bugs, under the more politically palatable label of astrobiology. Right now, NASA is eyeing the dusty surface of Mars (where water once flowed) and the likely ocean under the ice of Jupiter's moon Europa as sites for primitive life-forms. One recent false alarm: the much trumpeted Martian meteorite found in Antarctica apparently does not contain convincing evidence of the existence of microorganisms on the Red Planet, as originally claimed.

But the grander dream--of contacting extraintelligent E.T.s like those canal-building Martians imagined by the early 20th century astronomer Percival Lowell--lives on in the radio and optical searches underwritten by private outfits like Drake's SETI Institute and the Planetary Society. And even scientists dubious of success don't want to be spoilsports. They agree on the importance of continuing the quest, not just for microbes on Mars or Europa but also for those faint signals from some remote world--if only to underscore the preciousness of life and the importance of protecting perhaps its lone example. Admits Drake: "Even a negative answer is better than no answer at all."

Maybe you'd like to try tracking down E.T. yourself? If you have a PC or Mac that sits idle at least a few hours a day, you can join the 1.7 million people who have downloaded SETI@home, a free screen saver (available at setiathome.ssl.berkeley.edu that uses your computer's downtime to help sort through the reams of noisy static gathered by radio telescopes. The odds of pulling a Jodie Foster (who snared the elusive extraterrestrial signal in the 1997 sci-fi flick Contact) are a zillion to one. But if you fail--or even if you succeed--nobody's going to burn you at the stake.