Usually, when people think about finding extraterrestrial intelligence, they think of radio transmissions -- a trope that has been the basis of dozens of movies and television shows (Contact and Starman immediately come to mind). Just two days ago I looked at a new approach to detecting biosignatures -- traces of living things, usually in the context of life on other planets -- which involved arguments having to do with complex biochemistry.
Then yesterday, I ran into a new study from the SETI (Search for Extraterrestrial Intelligence) Project describing a recently-developed deep learning technique which goes back to radio astronomy -- and that has already uncovered eight "signals of interest" from previously-analyzed radio telescope data.
Now, before we go any further, allow me to state up front that no one (well, no one credible) is saying any of these signals actually come from you-know-who.
But this finding does give us alien enthusiast types some hope for answering the Fermi paradox -- "If life is common in the universe, where is everyone?" -- with two rejoinders: (1) we've only studied a vanishingly small slice of the star systems even in our own galaxy; and (2) our previous techniques for analyzing the radio emissions of the systems we have studied still missed some signals that by previously-accepted criteria should warrant a closer look.
All eight signals of interest shared the following three characteristics that put them in the "curious" column:
- They were narrow-band -- i.e. only peak at a narrow range of frequencies. Radio signals from natural sources tend to be broad-band.
- They had non-zero drift rates, meaning they were not moving with the same speed as the observatory. This rules out terrestrial sources, a constant source of interference with radio telescope data.
- The signals occurred only at specific celestial coordinates, and the intensity fell off rapidly when the telescope moved from being aimed at those coordinates.
All of these are features you would expect from radio transmissions from an extraterrestrial intelligence."In total, we had searched through 150 terabytes of data of 820 nearby stars, on a dataset that had previously been searched through in 2017 by classical techniques but labeled as devoid of interesting signals," said Peter Ma of the University of Toronto, who was lead author of the paper, which appeared in Nature Astronomy. "We're scaling this search effort to one million stars today with the MeerKAT telescope and beyond. We believe that work like this will help accelerate the rate we're able to make discoveries in our grand effort to answer the question 'are we alone in the universe?'"