Get the Mach newsletter.
By Seth Shostak

For more than a half century, we’ve been scanning the skies for radio signals that might be evidence of an alien civilization. Now physicists at the University of California, Santa Barbara are trying a different approach: scanning the skies for light beams that are monstrously intense. It’s a promising approach that could uncover aliens that have equipped themselves with the mother of all laser pointers.

The idea of using light beams to signal from one world to another isn’t new — even the Victorians considered it. In 1874, the Finnish mathematician Edvard Engelbert Novius proposed wiring up 22,000 light bulbs and using curved mirrors to focus their glow on Mars, thereby alerting Red Planet residents that they had neighbors on the third rock from the sun. He didn’t get the funding.

The Santa Barbara plan is to reverse Novius’ scheme and look for aliens who might be signaling us. Or, more accurately, inadvertently spilling light in our direction with a light source brighter than a blowtorch. The scientists plan to search for such high-tech luminaries camped out in the Andromeda Galaxy, which at 2.5 million light-years away is the nearest large galaxy to our own Milky Way.

This effort is an offshoot of another project developed at the university. Several years ago, faculty physicist Phil Lubin suggested syncing up a phalanx of high-powered lasers to produce a truly blinding light source. His idea was to use this super-laser to kick matchbook-sized space probes to nearby stars at roughly 20 percent the speed of light. This is difficult, but not impossible, and Lubin’s plan is now getting financial support from NASA and Breakthrough Starshot, a private initiative funded by venture capitalist Yuri Milner. It’s exciting to think we could send probes to the nearest stars fast enough that the project scientists will still be alive when the probes reach their destination.

But Lubin and his students also cooked up an ancillary experiment: a search for alien societies so advanced that they’ve already built powerful lasers for their own interstellar launches. These light sources would be easy to see even at astronomical distances. Indeed, by some reckonings, if you were looking down the beam of such a laser even from very far away, it would outshine stars, quasars, supernovae and — well — anything in the universe. You would notice.

The Santa Barbara team plan to use small telescopes to repeatedly take photos of Andromeda. Then they will compare these pics with older photos to see if any new “star” has appeared — possible evidence of a non-natural source. The process will be automated, and the survey can go on as long as there are interest and support.

Radio telescope antennas like these could be key in discovering life that exists outside of our galaxy.Martin Bernetti / AFP - Getty Images file

Why Andromeda? The reason is simple: choosing a nearby galaxy means the project can quickly reconnoiter a vast swath of extraterrestrial territory.

Andromeda, like the Milky Way, is thought to contain a trillion or so planets, a fact that led the Santa Barbara physicists to inventively dub their effort the Trillion Planet Survey. Most conventional searches for E.T. look for signals from nearby star systems one at a time. By examining an entire galaxy at once, the Santa Barbara scientists aim to greatly increase the chance of finding something.

There are some worries. Even if Andromeda contains a society whose super-bright lasers routinely stab the sky, the rotation of their home planet might cause this beam to sweep over Earth very quickly. If so, it could easily be missed. It’s also worth noting that Andromeda — which you can check out yourself with binoculars — has been studied nearly as much as the Bible. No one has ever seen any puzzling bright lights. In addition, astronomers hunting for supernovae have surveyed millions of other galaxies with automated telescopes. They’ve found many exploding stars, but no super-lasers.

Of course, failure to find these things doesn’t prove they’re not there.

The search for aliens has always assumed that advanced beings will either transmit an unnatural-looking signal or construct some artifact large enough to be seen with a telescope. But few searches have eyed as much cosmic real estate as the Trillion Planet Survey plans to do. And who knows? It just might turn up some society that’s truly enlightened.

Dr. Seth Shostak is senior astronomer at the SETI Institute in Mountain View, California and host of the “Big Picture Science” podcast.

Want more stories about space aliens?