March 7, 2021

Questions remain about Proxima Centauri and alien technosignatures

Painting of Proxima Centauri

Back in December, we learned that researchers with the Breakthrough Listen Project (BLP) had detected a strange signal believed to have come from the neighborhood of the nearest star to our sun, Proxima Centauri, a little more than four light-years from Earth. The nature of the signal suggested that it might (possibly) have been of a technological origin. This caused a great deal of excitement for obvious reasons, but the news just as quickly created quite a bit of controversy.

Debates quickly erupted, with one camp arguing that this might be the long-awaited sign of ET phoning home. Others equally rapidly concluded that such speculative assertions were hogwash and the signal, named BLC-1, was either a human-created transmission or the natural emanations of some unknown phenomenon. Since that time, additional analysis has been published, but little seems to suggest that a definitive answer is at hand.

To review a couple of specifics, the signal was detected in 2019 and the BLP team has been analyzing it ever since. The attention-grabbing aspect of BLC-1 was that it came in on a very tight band at 982 megahertz. It also exhibited a doppler shift, suggesting that the origin was moving, perhaps indicative of a planet in motion. This shifted attention to Proxima b, the roughly Earth-sized, rocky world orbiting close to the red dwarf star in its habitable zone.

We finally saw what I thought might be as close to a definitive answer as we were likely to get.

After various experts invested the time to investigate the available data, we finally saw what I thought might be as close to a definitive answer as we were likely to get. Matt Williams, writing at Universe Today, published an article a few days ago with the depressing, if nearly definitive title, “According to the Math, it’s Highly Unlikely That an Intelligent Civilization is Located at Alpha Centauri.”

“Aha!” I thought to myself. Finally someone has applied some math to the problem and ruled this out as any sort of technosignature. I was envisioning some brilliant astrophysicist breaking down the details of the signal and finding something about the frequency or amplitude that pointed to a match with some known phenomenon or even a wayward terrestrial source. Sure, I had been hoping the answer was aliens, but then again, that’s what I always hope. I would be satisfied with the answer, if a bit disappointed, as long as we were following the science.

The problem with that conclusion was the there was very little “math” involved in the process followed to reach that determination. Williams was relying on a study published by two scientists from Harvard University. Rather than a mathematical analysis of BLC-1’s transmission properties, their conclusions were almost entirely based on the Copernican Principle. That’s the traditional belief among cosmologists that ‘planets like Earth and the life it supports are likely to be representative of the norm.’ As such, human beings ‘are not in a unique and privileged position to observe the Universe and that our perspective is likely to be representative of the norm.’

They weren’t saying that BLC-1 was definitely a sign of technology. They weren’t saying that it was definitely natural or even man-made.

Starting from that philosophy, they then calculated that the odds of another intelligent species existing on a planet orbiting the star closest to our own were on the order of one in one hundred million. They weren’t saying that BLC-1 was definitely a sign of technology. They weren’t saying that it was definitely natural or even man-made. In fact, they weren’t saying anything specific about the signal at all. They were simply taking established assumptions about the frequency of suitable stars having planets orbiting in their habitable zones and saying that the odds of Proxima b having a technologically advanced civilization there were extremely unlikely.

In response to that I would simply reply that even if true, unlikely things can and do happen all the time. I would also note (and I’m not the first to say this) that our assumptions about the commonality of Earthlike worlds in the galaxy and how often they produce life are based on a sample size of precisely one world… ours. We may be alone in the universe. Or the Milky Way could be lousy with lifeforms that we simply haven’t managed to detect. We just don’t know yet and we won’t until we’re able to gather more data.

So what do we really know about BLC-1 and is there any reason to suspect it could represent non-human technology? There are pros and cons to be taken from the information released thus far. First of all there is the frequency. We checked with the Federal Communications Commission and it is well established that 982 megahertz is a frequency in the UHF range that’s regulated by the FCC. It’s at the low end of a band that is reserved for Aeronautical Radionavigation (Mobile). In other words, airplane transponders use it as a sort of GPS for planes.

Could BLP have erroneously picked up a signal from a 737 that was bouncing around in some unusual atmospheric conditions?

So could BLP have erroneously picked up a signal from a 737 that was bouncing around in some unusual atmospheric conditions? We can’t rule that out. Speaking as someone who worked as a radar technician for many years, I can tell you that transmitted UFH signals can do some really weird things when the conditions are right. But a few factors would appear to make this explanation at least a bit less likely. First of all, BLP incorporates numerous “filters” in their algorithms to eliminate such conventional explanations. Also, someone knows where just about every plane on the planet is flying at any given time. If BLP missed the source of this as being some conventional plane it was a major snafu.

Then there’s the fact that BLC-1 was basically a dead carrier. There was no data embedded in it via either frequency or amplitude modulation. (FM or AM.) We don’t generally waste the resources required to create such a transmission to send zero data. One could easily argue that the same could be said of a potential alien civilization. I suppose so, but I have no idea what the regulatory guidelines are at the Proxima b equivalent of the FCC, so I wouldn’t venture to speculate.

How about the natural space phenomenon theory? If you like, I suppose it can’t be ruled out either. But the galaxy is a very noisy place and all of the “talkers” out there (e.g. stars, black holes, magnetars and gas giants) tend to spew out emissions on a vast range of frequencies. I haven’t yet found any research identifying a stellar phenomenon that pings away on a single, defined frequency. Again, anything is possible in a limitless universe, but it would be quite unusual.

So does this mean I’m saying that aliens are the number one candidate? Of course not. We have no way to draw that conclusion. But it also seems to me that ruling out the extraterrestrial technosignature theory entirely, or even placing it at staggering odds of improbability, might be a bit hasty and shortsighted. Instead, we should continue cheering for the Breakthrough Listen Project and the work they are doing and keep our ears open. The next thing they hear might be remarkable beyond description and I’d prefer to hang on to my hopes and dreams.