Is there anyone out there?
NASA/SDO
We may have missed signals from intelligent aliens due to solar wind. Researchers from the Search for Extraterrestrial Intelligence (SETI) Institute say this means we’ve been looking for the wrong kind of signal, potentially failing to detect promising evidence of extraterrestrial life, but the chances of a future discovery are now higher.
The non-profit organization conducts research to prove the existence of alien life, which includes listening for extraterrestrial radio signals that cannot be explained by natural cosmological phenomena.
Such a signal was previously expected to be a sharp, distinct radio signal in a narrow frequency range. But the new research suggests that such signals sent from distant planets may end up getting weaker and broader in frequency band – essentially a bit blurry – as they pass through the plasma winds of the stars.
Vishal Gajjar and Grayce Brown at the SETI Institute calculated the magnitude of the effect on radio transmissions from spacecraft in our own solar system, and extrapolated it to other stellar environments. They found that a 100 megahertz signal could be expanded as much as 100 hertz – enough to “fall below traditional detection thresholds”. A space weather event can similarly increase the amount of broadening experienced by a signal by several orders of magnitude.
Simon George of the SETI Institute says there is also growing consensus that looking for narrow radio transmissions accidentally beamed through space is not the way to detect distant life. “Tthe idea that an intelligent civilization would send out such signals is becoming outdated, especially when you look at how communications and so on have developed since the 1960s,” he says. “There’s been a dramatic move towards broadband and spread-spectrum techniques, as these can carry far more information.”
“One way to look at this is to treat Earth as an exoplanet being seen by an alien civilization, a theme I often hear around SETI,” says George. “The bottom line is that while Earth was a strong narrowband source in the 1960s, there is much less now with a continuous downward trend. Of course, if an intelligent civilization intentionally sent out a beacon designed to be obvious and easy to detect, either for a ‘we’re here’ message or some other alien purpose, then that’s a different story.”
John Elliott of the University of St Andrews, UK, says he chooses to see the news as the glass half-full, rather than half-empty: it means past searches may have missed evidence, but it also means future searches will be more likely to succeed.
“We’ve been doing active research for over 50 years, and that’s a blink of an eye, isn’t it, when you think about it,” says Elliott. He says it’s not just the distortion of signals that hindered previous searches, but insufficient technology to detect and extract signals from the noise – something that is changing as computing power and AI become more powerful. “Until recently, we really haven’t had the equipment, the computing power, to do anything really important. We’ve been kind of struggling in the dark,” he says. “Project it forward another 1,000 years, which is just another heartbeat, can you imagine what our technology is going to be like? It’s going to be magic.”
Eric Atwell of the University of Leeds, UK, was involved in SETI around the turn of the millennium, and quantifies the discovery as perhaps increasing a 0.0001 percent chance of finding an alien signal to 0.0002 percent.
“It’s still a very low probability,” he says. “I don’t think they’ve wasted their time. They’ve tried things, and they have pretty strong evidence that what they’re trying doesn’t work, because they haven’t found anything yet.
“What they’re doing is trying to detect strange signals that can’t be put down to known astronomical properties, but it’s still a pretty hit-or-miss way of finding intelligent life,” Atwell says.
He is skeptical that passively waiting for evidence of life, accidentally sent, is the right approach if we eventually want to talk to aliens. “If there really are aliens out there and they want us to find them, they will send us a much more explicit signal,” he says.
Other groups, such as the organization Messaging Extraterrestrial Intelligence (METI), take a different approach to finding alien life. They plan to actively broadcast signals to other planets, in case distant life is listening for signals like we do.
Topics:
