The mysterious "alien signal" is fake

On October 25, American researchers pointed out in two papers in Nature Astronomy that the Proxima Centauri radio signal detected by the Australian telescope in 2019 appeared to come from Earth, not aliens.

The $100 million alien intelligent search project, Breakthrough Listening, funded by Russian billionaire Yuri Milner, took a closer look at the unusual radio beams discovered in 2019 and found that they didn't come from aliens at all. "The signal comes from artificial radio interference from some technology and may come from the Earth's surface." Sofia Sheikh, an astronomer at the University of California and co-author of the two papers, said.

The signal, known as Breakthrough Listening Candidate 1 (BLC1), came from the direction of centauri's immediate neighborhood and was detected by the 64-metre-long Parks Muriyan Radio Telescope in southeastern Australia. During its observations, the telescope captured more than 4 million radio emissions of different wavelengths, one of which appeared to be a precise radio beam with a frequency of about 982 megahertz. On April 29, 2019, it shone for about 2.5 hours, slowly increasing in frequency and then disappearing.

The researchers performed a series of attribute checks for each "hit" found. One criterion is that if the signal comes from a distant planet orbiting a star, the observed frequency should change slowly and smoothly as the planet rotates and orbits. Of Parkes' 4 million observations of proxima, only about 1 million prove this. The second major criterion is that the signal should disappear when the telescope is slightly pointing at the target star system farther away. This narrows the range to 5160 signals.

BLC1 is special in that the frequency band it covers is very narrow, excluding all possible sources of astrophysical radio waves. In addition, within 1,000 km of the observatory, there is no registered transmitter using this frequency, and it lasts longer than radio signals from aircraft or satellites passing above the telescope.

Of the millions of signals analyzed by the Breakthrough Listener team so far, this is the only one that looks like it could have been from an alien.

After discovering and labeling BLC1, Sheikh's team looked for similar signals by comparing archival observations of the proxima star system, and found 60 other signals with different frequencies that were almost identical to BLC1 in other ways. But all of these signals can still be detected when the telescope is pointing away from Proxima Centauri, suggesting that they were produced by human technology near the observatory.

While BLC1 was only detected when telescopes were aimed at the target star system, the researchers found that it could be a coincidence that the signal was most likely generated by two artificial radio transmitters that interfered with each other.

Sheikh said in a statement: "In the mass of signals, the most likely explanation is still that this is a 'strange' signal from human technology that just fooled our filters in the right way." We still can't be 100% sure that BLC1 isn't a signal from extraterrestrial technology, but it now seems very unlikely that it was an extraterrestrial technology. (Xin Yu)

Source: China Science Daily