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 85-foot dish of a radio telescope at two nearby, sunlike 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 bemusement 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.
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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.”
What’s the message?
Critics say 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 got a lot of attention in San Jose, Calif., last month at the annual meeting of the ultra-mainstream American Association for the Advancement of Science.
As the scientists debated, 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.
“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.”
Astronomers say it’s likely that our galaxy has tens of billions of “habitable zone” planets. And of course (channeling Carl Sagan) our galaxy is just one of billions and billions of galaxies. But how many of those potentially habitable planets out there actually have life? No one knows, because we don’t yet know how life began on Earth. How likely is it that simple, microbial life will evolve into complex, multicellular organisms and eventually into creatures with large brains? We don’t know, because we have only the one data point of life: on Earth.
Do intelligent creatures tend to be communicative and potentially detectable? No idea. Also: Do technological civilizations tend to survive a long time?
“Those factors are just completely unknown. It’s a great way to organize our ignorance,” said astronomer Jill Tarter, a pioneer of SETI who is neutral about the more active approach.
Drake said he doesn’t worry, as some do, that we would become depressed by contact with a superior civilization. Children aren’t depressed by the company of adults, he says. He compared SETI to doing research on ancient civilizations on Earth, such as the Greeks and the Romans.
“We’re going to do the archaeology of the future,” Drake said. “We’re going to find out what we’re going to become.”