Scientists have devised a new technique for finding and vetting possible radio signals from other civilizations in our galaxy — a major advance in the search for extraterrestrial intelligence (SETI) that will significantly boost confidence in any future detection of alien life.
Most of today’s SETI searches are conducted by Earth-based radio telescopes, which means that any ground or satellite radio interference — ranging from Starlink satellites to cellphones, microwaves and even car engines — can produce a radio blip that mimics a technosignature of a civilization outside our solar system. Such false alarms have raised and then dashed hopes since the first dedicated SETI program began in 1960.
Currently, researchers vet these signals by pointing the telescope in a different place in the sky, then return a few times to the spot where the signal was originally detected to confirm it wasn’t a one-off. Even then, the signal could be something weird produced on Earth.
The new technique, developed by researchers at the Breakthrough Listen project at the University of California, Berkeley, checks for evidence that the signal has actually passed through interstellar space, eliminating the possibility that the signal is mere radio interference from Earth.
Breakthrough Listen, the most comprehensive SETI search anywhere, monitors the northern and southern skies with radio telescopes in search of technosignatures. It also targets thousands of individual stars in the plane of the Milky Way galaxy, which is the likely direction a civilization would beam a signal, with a particular focus on the center of the galaxy.
“I think it’s one of the biggest advances in radio SETI in a long time,” said Andrew Siemion, principal investigator for Breakthrough Listen and director of the Berkeley SETI Research Center (BSRC), which operates the world’s longest running SETI program. “It’s the first time where we have a technique that, if we just have one signal, potentially could allow us to intrinsically differentiate it from radio frequency interference. That’s pretty amazing, because if you consider something like the Wow! signal, these are often a one-off.”