Claims by Chinese scientists that their “Sky Eye” telescope could have picked up signals from intelligent aliens were met with skepticism by an American colleague.
Dan Werthimer, a researcher at the Search For Extraterrestrial Intelligence (SETI) at UC Berkeley, California, and co-author of the research project (opens in new tab) who first detected the signals, told Live Science that the narrowband radio signals he and his fellow researchers discovered “are of [human] radio interference, not extraterrestrials.”
Natural sources do not normally produce these narrowband radio signals. Scientists picked up three such signals, apparently from space, in 2019 and 2022 using the world’s largest radio telescope – the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), dubbed the “Sky Eye”, which was conducting a preliminary exoplanet scan. in preparation for an upcoming five-year sky survey.
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News of the possible alien origins of the signals first appeared in an article published on Tuesday (opens in new tab) (June 14) in the official journal of the Ministry of Science and Technology of China, which contained claims made by the researchers that the team had discovered “several cases of possible technological vestiges and extraterrestrial civilizations from outside the Earth.”
A FAST official who was not directly involved in the research also said that a extraterrestrial origin for the signals was “likely”.
The allegations quickly went viral, spreading across Chinese state media and Chinese social media platform Weibo before being reported by the international press and Live Science. But Werthimer says that while the signals are certainly artificial, they are almost definitely from humans and not aliens.
“The big problem, and the problem in this particular case, is that we’re looking for signals from extraterrestrials, but what we’re finding is a zillion signals from terrestrials,” Werthimer told Live Science. “These are very weak signals, but the cryogenic receivers in the telescopes are super sensitive and can pick up signals from cell phones, television, radar and satellites – and there are more and more satellites in the sky every day. It’s kind of new to the game, and you don’t know them all. these different ways that interference can get into your data and corrupt it, it’s very easy to get excited.”
Despite this excitement, Werthimer’s Chinese collaborators were cautious to hide their most sensational observations, emphasizing the ultimate likelihood that the signals originated on Earth.
“These are several different narrowband electromagnetic signals from the past, and the team is currently working on more investigations,” Zhang Tongjie, chief scientist at the China Extraterrestrial Civilization Research Group at Beijing Normal University, said in the report. “The possibility that the suspect signal is some sort of radio interference is also very high and needs to be confirmed and ruled out. This can be a long process.”
The recent false alarm is one of several cases where alien-hunting scientists have been fooled by the noise of human activity. In 2019, astronomers detected a signal sent to Earth from Proxima Centauri – the closest star system to our sun (about 4.2 light-years distance) and home to at least one potentially habitable planet. The signal was a narrowband radio wave typically associated with man-made objects, prompting scientists to entertain the exciting possibility that it came from alien technology. Studies released two years later, however, suggested that the signal was likely produced by defective human equipment, Live Science previously reported. Likewise, another famous set of signals that supposedly came from aliens, detected between 2011 and 2014, were actually made by scientists making their lunches in the microwave.
“A lot of very sophisticated astronomers looked at this and we couldn’t figure out what it was for a long time,” Werthimer said, referring to the microwave lunch incidents. “Finally, someone found out they were happening at lunchtime.”
Radio interference is a big problem for a telescope like FAST precisely because of its scale and sensitivity. The 1,600-foot-diameter (500-meter) dish is powerful enough to detect Earth-like radio devices operating many light-years away, and the data it captures contains just under 40 billion observations per second. In this setup, catching a false positive is a lot like flipping a coin to get twenty heads in a row, Werthimer told publication Futurism (opens in new tab) — might seem like a remarkable result in its own right, but not when the coin has been flipped trillions of times or more.
And the less history a given research team has with a given radio telescope, the more likely they are to miss a subtle interference effect. According to Werthimer, the FAST telescope’s receiver can observe 19 different places in the sky at the same time. Scientists are used to ruling out interference if it appears in all 19, but if interference appears in only one (as it did with all three supposedly “alien” signatures detected in this case), even experienced researchers can be fooled.
With more and more satellites orbiting above our heads, Werhimer says this problem will only get worse.
“100 years ago, we didn’t really know how to do SETI. 100 years from now, I don’t think we’ll be able to do it from the ground up,” Wethimer said. “This could be a unique window into our history as Earthlings, where we can do good SETI research, where not every possible radio band is corrupted by our own signals.”
The possibility also remains that if aliens are sending us, or unwittingly leaking signals across the vast expanse of the cosmos, they may not be encoded in radio waves, but in ways we haven’t yet developed the technology to understand.
“It wouldn’t surprise me if we were on the wrong track. If you look at the history of SETI, the original ideas proposed about 200 years ago were things like ‘let’s build some great fires on Earth’; ‘let’s have some great mirrors that reflect the sunlight to the Martians or ‘let’s build some mile-long right angle triangles to show the aliens that we know the Pythagorean Theorem’, and now we look back and say these guys were idiots,” Werthimer said. . “So what do you mean 200 years from now people won’t look at us and ask why we don’t use tachyons or subspace communication? But you have to do what you know how to do.”
Despite the dismal probability that these signals have a terrestrial source, SETI astronomers are still fairly confident that we are not alone in the universe. And that one day, we might dig up something real amidst all our own small talk.
“I think it would be very strange if we were the only ones. If you look at the numbers, there are a trillion planets in the galaxy – five times as many planets as stars. Many of them are small planets like many of them have liquid water, so intelligent life , while not as common as bacterial life, can still be quite common,” Werthimer said. “Maybe they don’t want to interfere with primitive civilizations like us that are still killing each other. Maybe they have us in a big zoo to look at. Or maybe they’ve grown tired of technology and growth and are more interested in music and poetry.”
Live Science reached out to Zhang Tongjie for comment but had no response at the time of publication.
Originally published on Live Science.