In the ongoing search for technologically advanced extraterrestrial civilizations, at least we can say we tried.
Yuri Milner, the brains behind the Breakthrough Listen initiative (a 10-year, $100 million alien-seeking project which was even supported by Stephen Hawking), surveyed 1,327 stars in Earth’s backyard to see if E.T. was phoning home from any of their orbiting planets. It was an exhaustive search. Unfortunately, Milner and his team of international scientists just couldn't detect any signals. Nothing even went to E.T.’s voicemail.
Before you start thinking that the vast universe we’re floating in is totally devoid of any other life-forms, that number of stars only seems huge. The team's behemoth search that was recently published online is actually just the beginning. Maybe there was too much radio interference from our own planet. We also have no idea if we’re searching at the right frequencies, because aliens trying to get in touch could be using something that is totally incomprehensible to us.
“Together with other recent work from the resurgent SETI (Search for ExtraTerrestrial Intelligence) community, we are beginning to put rigorous and clearly defined limits on the behavior of advanced life in the universe,” said US Berkeley astrophysicist Danny Price and colleagues in a paper detailing the search results, published in The Astrophysical Journal. “We note that significant additional observational and theoretical work remains to be done before we are able to make general statements about the prevalence of technologically capable species.”
Milner’s team of researchers focused on stars within 160 light-years of Earth—the most massive publication of SETI data ever, but that's nothing when you realize there could be creatures transmitting signals from billions of light-years away. They covered a greater bandwidth than anyone has so far, and also used more advanced technology than previous efforts. The team also unearthed many signals that seemed extraterrestrial until they realized their origin was in things like satellites or radio waves from the home planet.
The stars were observed at frequencies ranging from 1.10 to 3.45 GHz. An Hz (hertz) is a single unit of frequency, and just one GHz (gigahertz) is equal to one billion Hz, and we have no idea what kind of frequencies a species that is still unknown to us may be using. Some stars that had been observed before were re-analyzed. The entire list of stars can be found right here.
“Our analysis is currently confined to only spectrally narrow drifting signals using our highest resolution data product,” Price and his team said, also noting that in the future, SETI scientists will be covering even larger bandwidths and using higher-res tech to detect signals.
Breakthrough Listen is hardly done yet. It’s the highest level of “SETI search strategies and capabilities” that boosts the abilities of existing radio telescopes, as the paper stated, and only just took off in 2016.
Meaning, the truth could still out there.