In classic science fiction, first contact with aliens seems foolproof: a giant, otherworldly spaceship lands on Earth, with creatures arriving to greet us or send us a message that we can easily and confidently translate. But in reality, The Search for Extraterrestrial Intelligence (known as SETI) It’s much more difficult.
[ Related: How scientists decide if they’ve actually found signals of alien life ]
In 1977, Ohio State University’s Big Ear Telescope While listening for signals from extraterrestrial intelligence, to everyone’s amazement, they recorded a signal that actually seemed to be real. Astronomer Jerry R. Ehman was so amazed that when he looked at the printout of the data, he wrote “Wow!” on the data and gave the signal a name.
“The Wow! signal is interesting to me because right now there’s nothing that can explain it. It’s exactly the frequency you choose when you’re trying to send radio waves far into space,” he explains. Seven RasmussenHe is an astronomer and the author of a forthcoming book on astrobiology. Life in Seven Numbers“Personally, this is my favorite tech signature to date,” they added. Wow! Signal It has yet to be redetected, leaving astronomers wondering what could have caused the strange observation.
Many objects in space actually emit radio wavesAstronomers use all wavelengths of light, including radio waves, to study the universe. For example, radio waves enabled the first famous images of black holes a few years ago, and they also helped Jocelyn Bell Burnell discover strange dead stars called pulsars. A disk of gas was exposed It acts as a breeding ground for planets around other stars.
All of these natural sources have one thing in common: they emit a fairly wide range of radio frequencies. Techno Signature—signs of technology, or signs of extraterrestrial intelligence—are so-called Narrowband Radio signals. Nature produces mostly broadband signals, but technology allows us to create highly focused messages.
“To create a really compelling technosignature, you definitely need something that was made with intent — be it a tool, a habitat, a message, a piece of art — but you need to be sure that it’s something that doesn’t occur in nature,” Rasmussen says. “Nature can create right angles (pyrite, bismuth, all kinds of crystals), but a house, for example, can’t.”
Beyond radio imaging, scientists have considered a variety of other technological features, from the sci-fi concept of a Dyson sphere harnessing the energy of an entire star to more familiar technological effects like the pollution of a planet’s atmosphere. But the idea of listening for alien radio signals is one that’s stuck in our minds. movie contact Here’s Jodie Foster listening to a radio telescope through old-fashioned headphones. (Unfortunately, it’s worth noting that real radio telescopes don’t generally work this way – they don’t have a Lightning port for plugging in earphones.)
Some astronomers are still searching for radio technosignatures, such as repeating Wow! signals coming from the direction of the constellation Triceratops. Breakthrough Listening Project, Use Radio telescopes such as the Allen Telescope Array in California or Green Bank Telescope, West VirginiaHowever, these studies were narrow-band and Interesting, perhaps specially selected wavelengths: 21 cm, important wavelength One of the rays of atomic hydrogenIt is the most abundant element in the universe.
At the same time, other astronomers are working to find a natural astrophysical explanation for the Wow! signal. Recently posted preprintsan international group of astronomers in Puerto Rico Arecibo ObservatoryIt was once the world’s largest single-dish telescope, The devastating collapse of 2020They found several signals similar to Wow!, but could easily determine that they were caused by cold hydrogen clouds drifting between the stars, and as a result, they claimed that the Wow! signal was probably astronomical in nature. Master A flare is a sudden brightening of one of these clouds caused by a nearby cosmic explosion, which Rasmussen describes as “the most plausible hypothesis I’ve heard so far, but I’d like to find a magnetar/SGR causing this maser before I can declare for certain that it’s a natural phenomenon.”
As the search for radio SETI expands, perhaps we will find more of these maser flares, other messages from space, or even repeats of the famous Wow! signal itself.
