Dan Werthimer has spent over four decades trying to listen to extraterrestrials.
A pioneering researcher in the field of astronomy known as SETI, or the Search for Extraterrestrial Intelligence, Werthimer’s work involves scanning the cosmos with massive ground-based radio telescopes to look for strange or unexplained signals that may be coming from of extraterrestrial civilizations.
If that sounds a bit like looking for a needle in a haystack, that’s because it kind of is.
In recent years, however, the search for extraterrestrial intelligence has become even more complicated. Growing demands for mobile services and wireless internet have cluttered the radio spectrum, creating interference that can skew data and add “noise” to scientific results.
“Earth is getting more and more polluted,” said Werthimer, chief technologist at the Berkeley SETI Research Center. “With some radio bands it’s already impossible to do SETI because they’re so full of TV transmitters, WiFI bands and cellphones.”
As wireless technologies continue to develop, the problem will only get worse, Werthimer said, potentially jeopardizing one of the primary means scientists have to search for intelligent life in the universe.
Werthimer was recently one of the authors of a pre-print study by Chinese researchers that identified a radio signal that several news outlets erroneously reported as having characteristics of an extraterrestrial civilization. The signal actually turned out to be radio interference, Werthimer said.
Targeted SETI research began in earnest in the 1980s and was entrenched in popular culture with the 1985 novel “Contact” by Carl Sagan, which was later made into a film in 1997 starring Jodie Foster.
At its heart, SETI research aims to answer the question: Are we alone in the universe? In the decades since scientists began listening for extraterrestrial signals, improvements in telescope technology and data processing have bolstered research, Werthimer said.
“Before, we were listening to one channel, and now we are listening to 10 billion channels,” he said. “Technology and science keep getting better.”
However, these technological leaps come with their own set of challenges. More satellites are being launched into low Earth orbit than ever before due to lower launch costs and cheaper materials to build spacecraft. Society’s growing reliance on wireless Internet and GPS navigation also means increased competition for radio frequencies.
“It’s valuable spectrum and people want more and more of it for day-to-day activities,” said Paul Horowitz, professor emeritus of physics and electrical engineering at Harvard University and a leading SETI researcher. “All of this means the radio spectrum is a mess these days.”
For SETI scientists, having relatively clear, unobstructed channels to scan the cosmos is invaluable. Wandering human interference not only creates more work for researchers to filter out, but can present itself as a falsely intriguing signal.
It’s an enigma astronomers know all too well, said Andrew Siemion, director of the Berkeley SETI Research Center and holder of the Bernard M. Oliver Chair for SETI Research at the SETI Institute in Mountain View, California.
To avoid red herrings, scientists often rely on repeatability, which can involve studying the same target for long periods of time to compare observations. Other times, researchers use what is known about human-made interference to assess their findings.
“As all these satellites are launched, our knowledge of what’s in space is also increasing,” said Siemion, who is also a principal investigator for Breakthrough Listen, a 10-year, $100 million initiative to search for intelligent aliens. life launched in 2015 by Stephen Hawking and Russian billionaire Yuri Milner.
He added that better situational awareness in space makes it easier to identify satellites and other forms of human interference.
“It helps us know that we’re not fooling ourselves into looking at a signal from a satellite and thinking it’s coming from a distant celestial source,” Siemion said.
Advances in machine learning also make it faster and easier for scientists to filter interference from their data, said Bruce Betts, chief scientist at the Planetary Society, who has been involved in SETI research since the organization was founded. in 1980.
Betts said these processing improvements should ensure that SETI research can continue for years to come.
“Even if you have more sources of interference, they will still follow certain frequency patterns and certain timing patterns,” he said. “Adding hundreds more satellites that all produce the same interference is really annoying, but you can develop systems to remove that.”
As the field of SETI research has evolved, so have other ideas about how to avoid interference in the future. Werthimer, Horowitz and others, for example, are investigating ways to search for extraterrestrial civilizations in the optical part of the spectrum.
Others have suggested setting up a radio telescope on the far side of the moon, where it would be protected from interference from Earth. Although technically feasible, such a project would entail significant costs, Horowitz said.
“SETI has struggled with almost zero government support for the past few decades, so no one will want to do it in a budget-constrained period of time,” he added.
Still, despite technical and funding challenges, interest in SETI research has grown over time, according to Betts. Much of this can be attributed to the tantalizing possibility of finding intelligent life elsewhere in the universe, he said.
“More than most other discoveries, it would reframe a lot of our philosophical views of the universe,” he said. “Yeah, it’s a needle in the haystack, but if you find that needle, you have one of the most profound discoveries in history.”