SEARCHING FOR E.T.
Signals from space and messages from Earth to aliens
WOW! SOURCE?
Most signals from space suspected to be of alien origin have turned out to have a natural source, but one signal has refused to go away. This is what is known as the “Wow!” signal, picked up by the Ohio State University’s Big Ear telescope on the night of 15 August 1977 during a search for extraterrestrial intelligence (SETI) session. It was a brief blast of radio signal so powerful that Jerry Ehman, the astronomer who spotted it on the data printout, ringed it and wrote “Wow!” beside it (see David Hambling, “Is there anybody out there?”, FT356:14). The signal was in the electromagnetic frequency band of 1420.4056 MHz, which is produced by the element hydrogen, and Ehman said “Since hydrogen is the most abundant element in the Universe, there is good logic in guessing that an intelligent civilisation within our Milky Way galaxy desirous of attracting attention to itself might broadcast a strong narrowband beacon signal at or near the frequency of the neutral hydrogen line.” To be accepted as a signal from an alien civilisation, though, the signal must repeat – and “Wow!” never did. This means that while it is still considered the best candidate for an alien signal, it has never actually been confirmed as one – but nothing even remotely like it has been picked up since, despite astronomers repeatedly
Monkeys killed at least 250 dogs in a sustained revenge campaign
scanning the same area of the sky. Now, though, we do have a potential source for the signal. Astronomer Alberto Caballero has searched through a catalogue of stars from the European Space Agency’s Gaia satellite to see if there were any candidates. “I found specifically one Sun-like star,” he said. This was an object designated 2MASS 192819822640123, about 1,800 light-years away, that has a temperature, diameter and luminosity almost identical to our Sun. While no planets have so far been detected in the vicinity of this star, it is of a type that could have Earth-like worlds orbiting it, hospitable to a civilisation similar to our own that might have decided to send out a signal. As for the one-off nature of the signal, Caballero points out that whenever humans have attempted to communicate with other potential civilisations, we, too, have sent out single broadcasts, not repeating ones, such as the message sent toward the globular star cluster M13 in 1974 from the Arecibo radio telescope. livescience.com, 19 May 2022.
SHOULD WE MESSAGE ET? The Arecibo radio telescope collapsed in 2020, since when we have not had the means to transmit a message to the stars, but Jonathan Jiang, an astrophysicist at NASA’s Jet Propulsion Laboratory, and his team have been preparing a signal to send once we have the capacity to do so again. “We want to send a message in a bottle in the cosmic ocean, to say, ‘Hey,
we are here’,” he says, and hopes to time the transmission for the 50th anniversary of our last signal, the 1974 Arecibo message. He has announced the message plans in advance to open up a discussion as to whether we should send one at all; but as we are already radiating a bubble of signals from TV, radio and other technologies into space, which could one day be detected by aliens, Stuart Taylor, a member of Jiang’s team, thinks “it would probably be better, since they’re going to listen to us anyway, to send a positive message.” The message would be sent toward a ring of stars about 13,000 light years from the centre of the Milky Way, as this region is thought to contain several planets in the habitable zones of their stars. “If there are aliens, they are most likely to be there,” Jiang says. His message encodes information in binary describing basic maths, physics and biology, including descriptions of DNA, amino acids and glucose. It would also contain a map of the Milky Way, the Solar System and Earth itself, including information about the makeup of the planet and its atmosphere. It will also have a timestamp telling aliens when it was sent, using a universal measure of time based on the behaviour of hydrogen atoms. Jiang and his team are hoping that either the 500-metre Aperture Spherical Radio Telescope in Guizhou, China, or the Allen Telescope Array in northern California, which was designed to search for extraterrestrial signals, will have been upgraded to send signals by 2024, but they are not holding their breath for a reply. Their message with take 13,000 years to reach its target, and even the Arecibo message from 1974 has by now only travelled 0.2% of the journey to its target stars. livescience.com, 6 Apr 2022.
WHY AREN’T THEY HERE? The Fermi Paradox, named after the Nobel Prize-winning physicist Enrico Fermi, who first raised this contradiction, considers on one hand the vast age and scope of the Universe, which suggests that evidence of alien civilisations should be everywhere, and on the other the fact that this evidence seems to be completely lacking, and asks the question,
“So where is everybody?” Now, astrobiologists Michael Wong, of the Carnegie Institution for Science, and Stuart Bartlett, of the California Institute of Technology, have come up with a potential answer. Extrapolating from the way cities grow, they concluded: “Civilisations either collapse from burnout or redirect themselves to prioritising homeostasis, a state where cosmic expansion is no longer a goal, making them difficult to detect remotely.” They found cities have historically grown exponentially until they hit crisis points that cause them to experience rapid crashes in growth. Eventually, the crisis points come faster than innovation can deal with them and cities either collapse or undergo a “homeostatic awakening”. Considering civilisations to be like planetwide cities, Wong and Bartlett see the civilisations that survive as dealing with these crises by redirecting their production away from exponential growth to sustainable development and harmony with the environment. This would result in a stagnant and insular civilisation that would be difficult to detect remotely: “Either outcome – homeostatic awakening or civilisation collapse – would be consistent with the observed absence of civilisations.” They suggest that while these civilisations might still explore space, they wouldn’t do so on a scale that makes contacting Earth likely. The only time we might detect them would be when they are close to collapse, as they would be dissipating large amounts of energy in a “wildly unsustainable” way. “This presents the possibility that a good many of humanity’s initial detections of extraterrestrial life may be of the intelligent, though not yet wise, kind,” they add. livescience.com, 11 May 2022.
OR MAYBE THEY ARE? Beatriz Villarroel, a postdoctoral researcher at the Nordic Institute for Theoretical Physics, found something intriguing while working on a project called
“Vanishing and Appearing Sources during a Century of Observations”. This involved going over photos from before we could put spacecraft in orbit to look for astronomical phenomena that flare up briefly, then disappear. This is almost impossible today because of the ever-increasing number of satellites and bits of space debris orbiting the Earth, all of which produce brief flashes of light that could be mistaken for transients. Villarroel was working on plates from the Palomar Observatory Sky Survey, which ran from 1949 to 1958, when she found something weird: nine dots of light, all in a line, appearing in just one plate from 12 April 1950. “We found one image where nine stars were out there, and they vanished. And they are not there half an hour earlier, and they are not there six days later.” It is possible these are just faults in the photographic emulsion or scanning artefacts, but Villarroel is taking the possibility that they might be extraterrestrial objects seriously. In a paper published in 2021 Villarroel tried to find a more ordinary explanation for them. They ruled out astrophysical explanations, passing airplanes, asteroids and other known light sources as well as contamination caused by nuclear fallout, as no known tests happened in 1950. They have also published a subsequent paper detailing other instances of transient flashes of light that seem to line up. They are, however, wary of concluding that the images show alien technology. “We are very careful when we write our papers, because we are not sure if they are real or not,” says Villarroel. “We need to always assume that it is the most boring explanation.” In the past, potential alien signals have turned out to be the product of a faulty microwave in the astronomer’s staff room, while a whole new class of stars, “potassium flare stars”, were eventually found to be an artefact caused by light from matches used by researchers taking a fag break outside. inverse.com, 21 May 2022.