.webp "According to a project researcher, China's 'alien' signal was almost certainly caused by humans.") |
| The erroneous signals were discovered by China's massive FAST telescope, the world's largest radio telescope. (Image credit Xinhua/Ou Dongqu) |
An American colleague was skeptical of Chinese scientists' claims that their "Sky Eye" telescope could have picked up signals from intelligent aliens.
Dan Werthimer, a Search For Extraterrestrial Intelligence (SETI) researcher at the University of California, Berkeley, and a co-author on the research project that discovered the signals told Live Science that the narrow-band radio signals he and his colleagues discovered "are from [human] radio interference, not extraterrestrials."
Narrow-band radio signals are not typically produced by natural sources. Three of these signals, seemingly from space, were picked up by scientists in 2019 and 2022 using the world's largest radio telescope, the Five-hundred-meter Aperture Spherical radio Telescope (FAST), nicknamed "Sky Eye," which was performing a preliminary scan of exoplanets in preparation for a five-year-long sky survey.
The possibility of alien origins for the signals was first reported in a report published Tuesday (June 14) in the official newspaper of China's Ministry of Science and Technology, which claimed that the team had discovered "several cases of possible technological traces and extraterrestrial civilizations from outside the Earth."
One FAST official who was not directly involved in the research also stated that the signals' extraterrestrial origin was "likely."
The claims quickly spread through Chinese state media and the Chinese social media platform Weibo before being covered by the international press and Live Science. However, Werthimer believes that, while the signals are undoubtedly artificial, they are almost certainly from humans rather than aliens.
One FAST official who was not directly involved in the research also stated that the signals' extraterrestrial origin was "likely."
The claims quickly spread through Chinese state media and the Chinese social media platform Weibo before being covered by the international press and Live Science. However, Werthimer believes that, while the signals are undoubtedly artificial, they are almost certainly from humans rather than aliens.
"The big problem, and the problem in this particular case," Werthimer explained to Live Science, "is that we're looking for signals from extraterrestrials, but what we find is a zillion signal from terrestrials." "Although the signals are very weak, the cryogenic receivers on the telescopes are extremely 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 easy to get excited if you're new to the game and don't know all the different ways that interference can get into your data and corrupt it."
Despite the excitement, Werthimer's Chinese collaborators were careful to temper the more sensational remarks, emphasizing the likelihood that the signals originated on Earth.
"These are several narrow-band electromagnetic signals that are different from the past, and the team is currently working on further investigation," Zhang Tongjie, the head scientist at Beijing Normal University's China Extraterrestrial Civilization Research Group, said in the report. "The possibility that the suspicious signal is radio interference is also very high, and it must be confirmed and ruled out further. This could be a lengthy process."
The recent false alarm is one of several instances where noise from human activity has misled alien-hunting scientists. Astronomers discovered a signal beamed to Earth in 2019 from Proxima Centauri, the nearest star system to our sun (about 4.2 light-years away) and home to at least one potentially habitable planet. The signal was a narrow-band radio wave, which is typically associated with man-made objects, leading scientists to speculate that it could have come from alien technology.
However, studies published two years later suggested that the signal was most likely caused by malfunctioning human equipment, as previously reported by Live Science. Similarly, another well-known set of signals once thought to be from aliens, detected between 2011 and 2014, turned out to be made by scientists microwaving their lunches.
"A lot of very sophisticated astronomers looked at that for a long time and we couldn't figure out what it was," Werthimer said of the microwave lunch incidents. "At long last, someone realized they were happening at lunchtime."
Because of its size and sensitivity, radio interference is a major issue for a telescope like FAST. The 1,600-foot-diameter (500-meter) dish is powerful enough to detect radio devices operating many light-years away, and the data it collects contains just under 40 billion observations per second. Picking up a false positive in this setup is similar to flipping a coin and getting twenty heads in a row, Werthimer told Futurism(opens in new tab) — it may seem like a remarkable result on its own, but not when the coin has been flipped trillions of times or more.
And the less experience a research team has with a specific radio telescope, the more likely it is that they will miss a subtle interference-effect. The FAST telescope's receiver, according to Werthimer, can look at 19 different locations in the sky at the same time. Scientists are used to ruling out interference if it appears in all 19, but if it only appears in one (as it did with all three of the allegedly "alien" signatures detected in this case), even experienced researchers can be misled.
Wertheimer believes that as the number of satellites orbiting above our heads grows, the problem will only worsen.
"We didn't really know how to do SETI 100 years ago. I don't think we'll be able to do it from the ground up in 100 years "Werthimer explained. "This may be a once-in-a-lifetime opportunity in Earth's history to conduct fairly good SETI searches, where not all of the possible radio bands are corrupted by our own signals."
If aliens are sending us, or unintentionally 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 heading in the wrong direction. If you look back at the history of SETI, the original ideas proposed around 200 years ago were things like "let's build some big fires on Earth," "let's have some big mirrors that reflect sunlight to the Martians," or "let's build some mile-long right-angled triangles to show aliens we know about Pythagorean Theorem," and now we look back and say those guys were idiots "Werthimer explained. "So, what's to say that in 200 years, people won't wonder why we didn't use tachyons or subspace communication? But you have to stick to what you know."
Despite the dispiriting possibility that these signals are coming from Earth, SETI astronomers remain fairly confident that we are not alone in the universe. And that one day, among all of our own nonsense, we might find something real.
"It would be strange if we were the only ones. According to the numbers, the galaxy contains a trillion planets — five times more planets than stars. Many of them are small planets like Earth. Because many of them have liquid water, intelligent life, while not as common as bacterial life, could still exist "Werthimer explained. "Perhaps they don't want to get involved with primitive civilizations like ours, which are still killing each other. Perhaps they have us on display in a large zoo. Or perhaps they've grown tired of technology and growth and are more interested in music and poetry."
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