About that “alien technosignature” we found last month…


Last month we learned from the Breakthrough Listen project (BLP) about an intriguing signal they picked up a while back and have been analyzing to try to determine its source. The signal appears to have come from Proxima Centauri, the closest star to our own. And several aspects of the signal made it look like it could very well have come from a technological source rather than part of the noise that the cosmos is always blasting out. I stress the word “appears” because the jury is still out on this. The Washington Post picked up the story this week with some new input from the scientists involved in the process. Sadly, while they reported glowingly on the project overall, they appeared to throw some cold water on the idea that ET might be phoning our home.

On Dec. 18, the world learned that Breakthrough Listen, a privately funded search for extraterrestrial intelligence, had found its first official candidate signal. The signal’s existence lit up the Internet. Was BLC-1, as it’s called, finally our moment of contact? Breakthrough Listen scientists, now hard at work on a paper about their findings, were quick to explain that the answer was probably “no”: Given the wealth of human-made radio signal interference out there, BLC-1 will probably turn out to be of human origin.

Their preliminary conclusion, however, does not defuse the excitement of BLC-1. The fact that there’s a candidate at all is cause for celebration. That’s because something remarkable is happening in the science of life and intelligence beyond Earth. The age of “technosignatures” is dawning.

I’m generally pleased when I see the mainstream media picking up on more space exploration and science stories, particularly when it has anything to do with the work made famous by SETI. And BLP is definitely an exciting development and worthy of praise.

But I’ll confess to being a bit confused about the differences in this report and the one we originally received from not only BLP themselves, but Scientific American as well. Granted, we were all initially cautioned that they couldn’t definitively say the signal was both technological in nature and not of earthly origin. But they also pointed out that they have a vast number of “filters” in their system allowing them to skip past and eliminate possible candidate signals if they fail various tests.

Notice how the WaPo article finishes the first paragraph by saying that the BLC-1 signal “will probably turn out to be of human origin.” While it’s true that BLP didn’t entirely rule out the signal coming from Earth (and possibly being human in origin) they pointed to several factors that don’t sound at all as if this is the most likely conclusion. For one thing, the signal came in on a very tight frequency of 982 megahertz. That’s at the low end of a navigation band that’s largely unassigned and not many people are making use of it.

Further, if the BLC-1 was a technological signal of human origin, why did it have no data encoded in it? We don’t generally invest the time, money and resources to just send out dead carriers for no reason, but that signal wasn’t modulated. And why did it appear to be coming from Proxima Centauri? The filters BLP uses were supposedly able to rule out signals from our own satellites and probes.

It’s still not impossible that there’s a terrestrial explanation, but when I first read that the data was pointing away from a nonterrestrial source, I assumed that they meant they had figured out a natural phenomenon from space that could generate it. It had already been suggested that the BLC-1 signal could possibly have been generated by some “exotic quirk of plasma physics.” That seemed a lot more likely than doing an about-face and declaring that it’s most likely a signal generated here on Earth.

Only time will tell, I suppose. They’re still running tests and examining the data. But even if this does turn out to have a completely mundane but overlooked source, this project is still fairly young compared to the overall SETI efforts that have been going on for many decades. There’s a lot of space left to explore and who knows what BLP might still find? I continue to be both hopeful and excited about this.

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