Understanding the quest to meet our galactic neighbors.
Human beings have always wondered if they’re alone in the Universe.
In 1960, a young astronomer named Frank Drake decided to find out. He pointed an 85-foot antenna at two distant stars and started listening for signs of life. In that moment, a new discipline was born: the search for extraterrestrial intelligence, or SETI.
The epicenter of this search is the SETI Institute, an unassuming office building in Mountain View, California—the heart of Silicon Valley.
Seth Shostak, director of the Center for SETI Research at the institute, says the search for extraterrestrial intelligence is a lonely corner of science. “Worldwide, the total number of people doing this for a job, if you will, is maybe a dozen, maybe fifteen,” he says. “Something like that. It’s very small, terribly small.”
When the SETI Institute was founded in 1984, its primary purpose was to look for intelligent life using the tools of radio astronomy. But since then, they’ve expanded into astrobiology, the study of all life in the Universe.
“So could there have been life on Mars, is there maybe life on Mars today, the moons of the outer solar system, how did life get started, things like that,” explains Shostak.
Today, most of the researchers at the institute are astrobiologists, funded by outside grants. Oddly enough, only six people at the institute are looking for intelligence – the ‘I’ in SETI. Shostak leads that small team. He says they’ve come a long way since Frank Drake’s experiment in 1960.
“Instead of having a single antenna listening to one spot on the radio dial at a time, now we can have multiple antennas listening to millions of spots on the dial at the same time.”
They use the Allen Telescope Array, a sprawling field of 42 antennas at the Hat Creek Radio Observatory in Northern California. If the technology keeps improving, Shostak expects to make contact by about 2040.
What that contact will look like, we don’t know. But Shostak is pretty sure: Hollywood has not prepared us for the real aliens.
“You know the ones on TV, they have big eyeballs and grey skin, no hair, never smile, don’t tell any jokes, have no pets,” Shostak says, if we want to know what aliens would really be like, he says, we should look at our own civilization.
In about a century, we’ve gone from inventing radio technology to nearly developing strong artificial intelligence—machines that can learn and think just like humans can. Considering that the Universe is about 13.8 billion years old, it is likely that any civilization we’d be hearing from is highly advanced; they’ve probably already gone through a similar chapter of history, a similar leap in technology.
“In other words, most of the intelligence in the Universe is probably artificial intelligence,” says Shostak. “So if we pick up a signal, my guess is it’s coming from a machine.”
But so far, SETI hasn’t found any intelligence, artificial or otherwise. Which begs the question, where is everybody?
This question was formalized—and immortalized—in 1950 by the physicist Enrico Fermi. As the story goes, he was working on the Manhattan Project at Los Alamos National Laboratory when it occurred to him that if the Universe is as big and old as we think it is, and it’s full of intelligent civilizations, somebody probably would’ve colonized the Milky Way by now.
“If the galaxy has a lot of societies, and if only a few of them are interested in colonization, there’s been more than enough time for them to have done that, to have colonized the entire galaxy,” says Shostak. “We should see aliens everywhere, and we don’t seem to.”
The Fermi Paradox has led some to conclude that life is probably rare in the Universe. But Shostak doesn’t buy it. In recent years, NASA’s Kepler space telescope has surveyed thousands of star systems in the Milky Way, and about 1 in 5 of those stars is orbited by an Earthlike planet.
“That means there’s tens of billions of earthlike worlds in the galaxy,” says Shostak. “It’s a big number.”
The odds seem pretty good that there’s some life out there. Besides, if we’re totally alone, that could mean only one thing…”This place is a miracle,” says Shostak. “And, as a scientist, it’s very difficult to believe in miracles, because normally if you’re believing in miracles you’re only fooling yourself. Most things aren’t miracles.”
“Our planet’s not a miracle, but our planet may have been lucky,” says Don Brownlee, a professor of astronomy at the University of Washington and the co-author of Rare Earth: Why Complex Life is Uncommon in the Universe.
Brownlee and his co-author, paleontologist Peter Ward, argue that microbial life may be common in the Universe. But complex life—the kind we have on Earth—is, well, rare.
“There are a number of nice things the Earth has that’s promoted the evolution of higher organisms,” he says.
Things like environmental stability. We have plate tectonics that recycle carbon, acting like a thermostat to keep Earth liveable. Our large moon may also have an influence on the Earth’s axial tilt, helping to regulate the climate as well.
“Also Jupiter, interestingly enough, plays a role,” says Brownlee. It’s possible that Jupiter has steered asteroids in Earth’s direction over time. And without those asteroids, we wouldn’t have water. (The role of Jupiter in the Earth’s asteroid traffic is complex and contested—see more here.)
The point is, these and other factors have made life on Earth possible. And Brownlee says our planet seems to be the exception, not the rule. “The Universe is actually quite, quite hostile to life. It’s either too hot, or too cold, or not enough pressure, no water…”
Some say the rare earth hypothesis relies on a limited definition of “life” that it doesn’t take into account alien worlds with life forms we can’t even imagine.
“We can speculate about silicon-based life and so forth, life that might live in liquid helium or molten lead, but we have no physical basis for that,” says Brownlee. He thinks our theories should be based on the data we have. Which is why he believes SETI is important—because it’s looking for data where no one else is. “I don’t think it should be a national priority, but you know it’s certainly a good thing to do.”
Back at the institute, Shostak says SETI is far from a national priority. The SETI Institute used to be funded by NASA. But in 1993, when the Clinton Administration’s top priority was dealing with the deficit, the search for ET was an easy target. SETI’s biggest opponent was Richard Bryan, a senator from Nevada. He characterized the search as “foolish and wasteful,” and successfully urged lawmakers to cut the program’s annual budget of approximately $10 million. With the federal money dried up, the SETI Institute was reincarnated as a non-profit research organization, relying largely on donations.
“The money that funds our SETI research is due to people who just send us a check because they think this is an interesting thing to do,” says Shostak.
The biggest donors have always been their neighbors in Silicon Valley. The founders of Intel, Microsoft, and Hewlett-Packard have all given money. Most recently, Franklin Antonio, co-founder of the wireless communications company Qualcom, gave $3.5 million. Still, Shostak and the team struggle to bring in just 1 or 2 million dollars a year—the bare minimum they need.
Even on a shoestring budget, one researcher is planning way, way ahead.
Doug Vakoch is the Director of Interstellar Message Composition. He spends a lot of his time brainstorming on the issue with linguists, anthropologists, and other experts who typically aren’t involved in the SETI conversation. The goal? To develop the perfect message to send to the extraterrestrials.
After years of just listening, Vakoch thinks it’s time to amp up the search, and send a message of our own. This idea is called “Active SETI.” And some scientists think it’s a really bad idea. “No less a person than Stephen Hawking has said, ‘Whatever you do, don’t transmit to the extraterrestrials. They may come and strip-mine our planet.'”
Those who oppose Active SETI say we don’t know what’s out there, so we shouldn’t advertise ourselves. (Some experts have even circulated a petition protesting the idea.) But to Vakoch, that fear doesn’t make sense.
“Even if another civilization can travel between the stars,” says Vakoch, “if they’re hostile, if they want to come here and eat us or simply destroy us…sad news is, it’s too late.”
Earth has been leaking radio and television transmissions into space for decades. Vakoch admits that a targeted broadcast would be more powerful than our unintentional cosmic noise pollution, but the fact is, if anyone’s out there listening, they’ve probably already heard us. So Vakoch believes we might as well send a proper greeting.
“When we think about how to communicate with another civilization, we can’t count on them knowing English or Swahili or Russian, so we have to come up with something universal.”
If another civilization is receiving our message at all, that means they can build a radio telescope, which means they’re engineers; they understand math and physics.
“They probably know at least 2+2=4. So that’s a starting point,” he says. From there, Vakoch says we might be able to tell them about something as abstract as altruism, perhaps using the language of genetics.
“Or consider music,” Vakoch says. “Music captures something quintessential about what it is to be human, but if you think about it, the structure of music is very much a mathematical and physical thing. So once we can communicate something about mathematical ratios and notions of time and frequency and duration, we can start describing our music.”
It’ll be a difficult task, expressing human experience in truly universal terms. But even if we never make contact, Vakoch says thinking about what we might say is a worthwhile pursuit.
“The reality is, there may be no extraterrestrials out there,” Vakoch shrugs. “I hope to god there are, but if at the end of the day, the only thing we have accomplished is learning more about ourselves by trying to make contact, the whole project will still have been worth it.”
For now, SETI won’t be sending any messages into space. But as long as they have the money, they’ll keep doing what they’ve always done: exploring the Universe through the radio dial, listening for signs of life.