For decades, researchers at the Search for extraterrestrial Intelligence (SETI) have been using their massive radio communications apparatus to sift through the white noise of outer space in an attempt to discern any kind of signal that may be indicative of alien life. Over the years, they’ve even had some close calls with revelation, including one powerful signal recorded in 1977 that was never found repeating. It was such a significant signal that Astronomer Jerry R. Ehman circled it on the printout and wrote “wow!” in the margins alongside it — giving the signal its name. However, because efforts to find the signal once again proved fruitless, there was no way to investigate what caused it.
As recently as two years ago, SETI began picking up a different kind of signal — one that scientists can’t explain but believe that it isn’t born out of an attempt to communicate: fast radio bursts (FRBs). These FRBs are massively powerful; so powerful, in fact, that the leading natural explanation scientists can come up with is that they’re from “highly magnetized neutron stars, blasted by gas streams near to a supermassive black hole.”
The problem with that explanation is that the bursts aren’t all coming from one specific place, but they are all coming from one specific region of space. That means, based on SETI’s readings, that those specific circumstances would need to be commonplace within galaxy FRB 121102 (where the signals are coming from) but not common at all elsewhere in the known universe. If they were, these FRBs would be picked up from all-around us all the time, rather than from one specific galactic neighborhood. While FRBs have been picked up from other parts of space, they have never been recorded with the frequency or regularity scientists have seen out of galaxy FRB 121102.
A recent SETI press release explains:
Fast radio bursts, or FRBs, are bright pulses of radio emission, just milliseconds in duration, thought to originate from distant galaxies. Most FRBs have been witnessed during just a single outburst. In contrast, FRB 121102 is the only one to date known to emit repeated bursts, including 21 detected during Breakthrough Listen observations made in 2017 with the Green Bank Telescope (GBT) in West Virginia.
Recently, SETI began using artificial intelligence to sift through previous data gathered from that region of space, using it to comb through thousands, if not millions, of lines of code looking for any anomalies. To their surprise, those 21 repeated bursts were not the only FRBs recorded from FRB 121102 recently. In fact, their algorithm found a shocking 72 more. That means SETI has now recorded 93 total FRBs from the same region of distance space.
The cause of these FRBs remains a mystery. They could potentially be caused by a unique set of natural circumstances we have thus far only discovered in this one area. Others contend that they may be signs of an advanced alien civilization operating in galaxy FRB 121102, though surprisingly, most of those theories suggest that the radio signals actually have nothing at all to do with communication.
“Fast radio bursts are exceedingly bright given their short duration and origin at great distances, and we haven’t identified a possible natural source with any confidence,” said Harvard professor Avi Loeb in a press release. “An artificial origin is worth contemplating and checking.”
Loeb posits that these massive bursts of energy might actually be a part of a near-light-speed propulsion system not unlike the solar sails mankind is currently experimenting with. A planet-sized power source could potentially release a massive burst of energy that propels a spacecraft like wind on a sail. Based on the amount of energy released in each burst, Loeb says they could propel a craft that weighs millions of tons at velocities that are approaching the speed of light.
“That’s big enough to carry living passengers across interstellar or even intergalactic distances,” agreed Harvard researcher Manasvi Lingam.
Interesting as that theory may be, for now, there’s no way to peer 3 billion light years away to see for sure, and frankly, if the signals have been traveling at the speed of light for 3 billion years to reach us, there may be nothing left there to see anyway. For now, there’s nothing to be done but continue to gather data and hope that some more solid conclusions will be forthcoming in the future.
“This work is only the beginning of using these powerful methods to find radio transients,” said Gerry Zhang, a UC Berkeley Ph.D. student working on the program, in the SETI statement. “We hope our success may inspire other serious endeavors in applying machine learning to radio astronomy.”