If Aliens Are Flashing Laser Beams at Us, We Now Have a Way to Detect Them

Planet Earth with sunrise and flare glint in background. — (Image credit: Shutterstock)

Are aliens using super powerful flashlights to get our attention? Astronomers think there's a chance they are.

Since the invention of the radio, humans have been silently listening to the stars, wondering if we are alone in the universe. But if intelligent alien life does exist, the extraterrestrials could be using other forms of technology to communicate. Astronomers are beginning to not only listen to the cosmos but also gaze toward it for other signs of alien tech: laser beams.

"With the addition of VERITAS, we're sensitive to an important new class of signals: fast optical pulses," Andrew Siemion, the director of Berkeley's SETI Research Center, said in the statement. "Optical communication has already been used by NASA to transmit high-definition images to Earth from the moon, so there's a reason to believe that an advanced civilization might use a scaled-up version of this technology for interstellar communication."

VERITAS has looked for such laser pulses from the mysteriously dimming Tabby's Star after some had speculated there could be an alien megastructure surrounding it that caused the odd dimming. If the most powerful lasers on Earth were used at Tabby's Star and pointed in our direction, VERITAS could detect them. Of the 1 million stars on the Breakthrough Listen target list, most of them are 10 to 100 times closer to Earth than Tabby's Star, meaning even weaker laser flashes from intelligent aliens could be detected.

The array of four 12-meter optical telescopes is traditionally used to detect gamma rays — high-energy radiation emitted by extreme cosmic objects like exploding stars and even black holes — in the night sky. When gamma rays hit Earth's atmosphere, they produce very faint blue flashes of light called Cherenkov radiation, because the particles travel faster than the speed of light through air. So the blue flashes are the light equivalent of a sonic boom. The telescope array's ability to detect and pinpoint the source of these short-lived blue flashes made it the perfect candidate to search for laser beams from distant stars and galaxies.

"We believe that life arose spontaneously on Earth, so in an infinite universe, there must be other occurrences of life," famed physicist Stephen Hawking said during the initiative's launch. "Somewhere in the cosmos, perhaps intelligent life might be watching these lights of ours, aware of what they mean. Or do our lights wander a lifeless cosmos, unseen beacons announcing that, here on one rock, the universe discovered its existence? Either way, there is no better question."