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This article was published 7/3/2015 (2088 days ago), so information in it may no longer be current.
It was near Green Bank, W.Va., in 1960 that a young radio astronomer named Frank Drake conducted the first extensive search for alien civilizations in deep space. He aimed the 25-metre dish of a radio telescope at two nearby, sun-like stars, tuning to a frequency he thought an alien civilization might use for interstellar communication.
But the stars had nothing to say.
So began SETI, the Search for Extraterrestrial Intelligence, a form of astronomical inquiry that has captured the imaginations of people around the planet but has so far failed to detect a single "hello." Pick your explanation: They're not there; they're too far away; they're insular and aloof; they're zoned out on computer games; they're watching us in mild amusement and wondering when we'll grow up.
Now some SETI researchers are pushing a more aggressive agenda: Instead of just listening, we would transmit messages, targeting newly discovered planets orbiting distant stars. Through "active SETI," we'd boldly announce our presence and try to get the conversation started.
Naturally this is controversial, because of, well, the Klingons. The bad aliens.
"ETI's reaction to a message from Earth cannot presently be known," states a petition signed by 28 scientists, researchers and thought leaders, among them SpaceX founder Elon Musk. "We know nothing of ETI's intentions and capabilities, and it is impossible to predict whether ETI will be benign or hostile."
This objection is moot, however, according to the proponents of active SETI. They argue that even if there are unfriendlies out there, they already know about us. That's because I Love Lucy and other TV and radio broadcasts are radiating from Earth at the speed of light. Aliens with advanced instruments could also detect our navigational radar beacons and would see that we've illuminated our cities.
"We have already sent signals into space that will alert the aliens to our presence with the transmissions and street lighting of the last 70 years," Seth Shostak, an astronomer at the SETI Institute and a supporter of the more aggressive approach, has written. "These emissions cannot be recalled."
That's true only to a point, say the critics of active SETI. They argue that unintentional planetary leakage, such as I Love Lucy, is omnidirectional and faint, and much harder to detect than an intentional, narrowly focused signal transmitted at a known planet.
These critics add it's bad form for scientists to attempt such interstellar communication without getting permission from the rest of humanity. Plus there's the question of what, exactly, a message to the stars ought to say.
Thus one of the greatest scientific mysteries -- are we alone in the universe? -- leads to a thorny political and cultural question: Who speaks for Earth?
This discussion about the proper protocols of communicating with aliens is not the most mainstream scientific debate ever concocted. But it got a lot of attention here in San Jose at the annual meeting of the ultra-mainstream American Association for the Advancement of Science.
Astronomer Jill Tarter, a pioneer of SETI who is neutral about the more active approach, organized a symposium on the topic. Before the symposium, two advocates of the idea, Shostak and Douglas Vakoch, appeared at a press briefing alongside science-fiction writer David Brin and planetary scientist David Grinspoon.
"Active SETI is a reflection of SETI growing up as a discipline," said Vakoch, a clinical psychologist who is the SETI Institute's director of Interstellar Message Composition. "It may just be the approach that lets us make contact with life beyond Earth."
But Brin, a signer of the petition protesting the campaign for active SETI, said we don't know what's out there and shouldn't presume aliens are benign. He said there are roughly 100 scenarios to explain why we haven't heard from the aliens so far. About a dozen of those scenarios are unpleasant, he said.
As the scientists debated one another, a white-haired, bespectacled man in the back of the room listened quietly: Frank Drake.
He is 84 years old, the beloved dean of the SETI field. He is the Drake of the famous Drake Equation, the formula he scribbled down in 1961 in advance of a meeting in Green Bank. His equation offers a technique for estimating the abundance of communicative civilizations.
He said he thinks it's too soon to engage in active SETI. We don't know enough.
"I think it's a waste of time at the present. It's like somebody trying to send an email to somebody whose email address they don't know, and whose name they don't know."
When Drake plugs his estimates into the Drake Equation, he comes up with 10,000 alien civilizations that we could detect if we looked in the right places with the right techniques.
"It's 10,000 that we can detect. There are a lot more," Drake clarifies. "A lot more young ones that can't be detected because they don't have the technology, and there are older ones that have technology that is so good that they don't waste any energy."
Why, a reporter asked Tarter, should we try to pick up signals from an alien civilization?
"We're curious how many different ways there are to do this thing called life," she said. "And we're curious if it's possible for us to have a long future."
That's because we'd most likely find a very old civilization, not a young one. It's a matter of statistical probabilities. The universe is 13.8 billion years old. If we pick up a signal, it is unlikely to be from a civilization that has only recently become communicative.
Tarter isn't discouraged by SETI's null result to date. She says our ability to detect signals, though much improved since 1960, remains limited.
"We've explored one eight-ounce glass of water out of the ocean," she says.
-- The Washington Post