Researchers may have found a new way to detect signals from advanced extraterrestrial civilizations.
of Einstein general relativity theory tells us that the gravitational pull of massive celestial objects can bend light. When it does, it focuses and magnifies the light like a telescope in an effect called gravitational lens. But visible light may not be the only thing affected by this process.
Graduate students in a course on search for extraterrestrial intelligence (SETI) at Penn State suggest that communication signals could also be amplified by gravitational lensing. And if possible, we might even be able to eavesdrop on extraterrestrial communications being relayed around the Sun.
Related: The Sun’s gravitational lens could help find life on exoplanets
The group hypothesizes that vast interstellar communication networks could use gravitational lensing to relay transmissions over great distances, similar to how cell phone networks operate here on Earth.
“Humans use networks to communicate across the world all the time,” Nick Tusay, a student on the course, said in a statement (opens in a new tab). “When you use a cell phone, electromagnetic waves are transmitted to the nearest cell tower, which connects to the next tower and so on.”
If probes are installed in specific positions near a star to take advantage of its gravitational lens, they could be used as relay points for this communication network. The students propose that if an advanced extraterrestrial species discovered this process, and used the sun as a relay point, we would be able to pick up these signals.
They tested this hypothesis by collecting data from Green Bank Telescope in West Virginia and looking for radio transmissions that could be relayed to our nearest stellar neighbors, located in the Alpha Centauri system.
“There has been some previous research using optical wavelengths, but we chose to use radio wavelengths because radio is a great way to communicate information through space,” said Macy Huston, another student on the course, in the release.
Although the students have not discovered any extraterrestrial transmissions, all hope is not lost. “Our search was limited to one night, so anything that wasn’t broadcast while we were observing wasn’t going to be picked up,” Tusay said. “Although our limited search may miss existing probes if they were not constantly broadcasting at these frequencies, this was a good test to see if this type of search is possible.”
And while the group hopes future students of the course will continue to listen in on extraterrestrial transmissions, gravitational lensing can also be used beyond the Earth. search for extraterrestrial life.
“Astronomers have considered taking advantage of gravitational lensing as a way to essentially build a giant telescope to observe planets around other stars“, said Jason Wright, professor of the course and director of the Penn State Extraterrestrial Intelligence Center, in the press release. “It was also considered a way for humans to communicate with our own probes if we ever sent them to another star. . “
A paper describing the technique has been accepted for publication in The Astronomical Journal, and a preprinted version (opens in a new tab) is available through the arXiv database.