Harvard astrophysicist Avi Loeb says that advanced extraterrestrial life is less speculative than dark matter or extra dimensions, or, as Scientific American observes, it’s never aliens, until someday, it is. The Guardian leaked the news that a “tantalizing” radio signal, BLC-1, appears to have come from Proxima Centauri, the closest star to the sun at just 4.2 light-years.
The signal was detected in archival data gathered last year by the Breakthrough Listen team using the Parkes radio telescope observatory, located 20 kilometers north of the town of Parkes, New South Wales, Australia in its searching for signals of radio-transmitting extraterrestrial civilizations in our Galactic neighborhood that are too narrow and well-defined to result from natural processes.
The signal cannot yet be dismissed as Earth-based interference, raising the remote possibility that is a transmission –a technosignature–from some form of advanced extraterrestrial intelligence. “We are scanning our galaxy in unprecedented detail,’ said Danny Price, Parkes Project scientist with the Breakthrough Listen project at UC Berkeley. “By trawling through these huge datasets for signatures of technological civilizations, we hope to uncover evidence that our planet, among the hundreds of billions in our galaxy, is not the only where intelligent life has arisen.”
The technosignature that scientists have been actively seeking for decades is communication signals. “We have a pragmatic definition for technology, which is the ability to deliberately modify an environment in ways that can be sensed over interstellar or interplanetary distances, including the unintended consequences of that modification,” observes SETI pioneer, Jill Tarter. “Life does this, but it doesn’t do it deliberately.”
“Only human technology seems to produce signals like that,” says Sofia Sheikh, a graduate student at Pennsylvania State University and the Breakthrough team member leading the signal analysis.. “Our WiFi, our cell towers, our GPS, our satellite radio—all of this looks exactly like the signals that we’re searching for, which makes it very hard to tell if something is from space or from human-generated technology.”
“It’s pretty expected that every now and then you’ll see something weird, but this is interesting because it’s something that’s weird that we’re having to think about the next steps,” says Sheikh.
British astrophysicist Lord Martin Rees suggests that aliens could exist in forms we can’t conceive. “They could be staring us in the face and we just don’t recognize them. The problem is that we’re looking for something very much like us, assuming that they at least have something like the same mathematics and technology.”
“It has some particular properties that caused it to pass many of our checks, and we cannot yet explain it,” says astrophysicist Andrew Siemion at the University of California, Berkeley and director of the Berkeley SETI Research Center, in an interview with Scientific American.
A Very Narrow Band of the Radio Spectrum
The faint signal is question occupies a very narrow band of the radio spectrum: 982 megahertz, specifically, which is a region typically void of transmissions from human-made satellites and spacecraft. “We don’t know of any natural way to compress electromagnetic energy into a single bin in frequency” Siemion says. He suggests that perhaps “some as-yet-unknown exotic quirk of plasma physics could be a natural explanation for the tantalizingly concentrated radio waves. For the moment, the only source that we know of is technological.”
Between April and May, 2019, he Breakthrough Listen team aimed the Parkes telescope at Proxima Centauri to study the colossal flares emitted by small red dwarf Proxima. While processing the data from those observations, Shane Smith, an undergraduate from Hillsdale College in Michigan working with Breakthrough, spotted BLC-1 that was narrow in bandwidth, appeared to drift in frequency, and vanished when the telescope was shifted to a different object. In the following days, four similar signals appeared, although some have been ruled out as radio interference.
“All of our SETI experiments are conducted in an absolute sea of interference. There are tons of signals,” Siemion says. ”It comes down to being able to tell the difference between a very distant technosignature and our own technology.”
Using artificial intelligence for future SETI searches, AI could identify something our mind cannot understand or accept. Could it in the future also go beyond our level of consciousness and open doors to reality for which we are not prepared?
Image credit: A, Cherney, CSIRO