It hasn’t been widely publicized, but the most extensive search for extraterrestrial intelligence ever undertaken has been up and running for more than four years.

Breakthrough Listen is a 10-year, $100 million space scanning project sponsored the Berkeley (California) SETI Research Center and funded by Russian billionaire Yuri Milner. Breakthrough Listen is the latest manifestation of the SETI (search for extraterrestrial intelligence) program, which has passed through multiple phases since its inception in the late 1970s. This privatized version of SETI will eventually aim its detecting devices at more than one million nearby star systems and 100 neighboring galaxies, searching for optical and radio signals that might indicate the presence of technologically advanced life.

Current sky monitoring operations are being carried out using two of the world’s most powerful telescopes: the 100-metre Robert C. Byrd Green Bank Telescope in Green Bank, West Virginia (USA) and the 64-metre Parkes Observatory Telescope in Parkes, New South Wales (Australia). Eventually, the new MeerKAT observatory telescope array in South Africa will join the project as well, and its 864 metres of cumulative magnifying capacity will dramatically expand Breakthrough Listen’s star scanning abilities.

So far, scientists associated with this new SETI iteration have completed analysis on data collected from 1,327 stars, all located within 160 light years of Earth. As of now, they’ve come up completely empty.

Not a single indicator of life has been found. No radio signals, laser traces, or anomalous activity covering any part of the electromagnetic spectrum.

“There’s certainly nothing out there glaringly obvious,” says Danny Price, an astrophysicist affiliated with the Berkeley SETI Research Center. Price was the lead author of an article printed in the June 17, 2019 edition of The Astrophysical Journal , which revealed the unremarkable results. “There’s no amazingly advanced civilizations trying to contact us with incredibly powerful transmitters.”

Overall, researchers analysed more than one petabyte, or one million gigabytes, of data collected in radio and optical wavelengths. A few possible hits were detected, but further checking revealed all to be false alarms.

While SETI searchers were undoubtedly disappointed to hear this news, its unlikely they were surprised. At different times SETI projects have been funded by governments, educational institutions, nonprofit foundations and rich individual investors. In each of these instances, no meaningful results have been obtained.

It’s reasonable to ask why this is so. Obviously, if humans are the only intelligent life form in the universe that would explain it. But that answer seems unlikely.

The universe is simply too vast to believe that we’re alone. Billions of Earth-like planets exist in other solar systems, and if evolution has occurred here there’s no reason to think it hasn’t happened elsewhere. So the lack of evidence for alien life calls out for a different explanation.

Some of the possibilities that have been raised include:

Interstellar interference

Radio or optical signals traveling astronomical distances might be reflected, deflected, disrupted or otherwise weakened or redirected by objects, forces, space distortions or other interstellar phenomenon we don’t yet understand.

Small sample size

SETI has been active for decades. But the universe has been active for billions of years, and its size after post-Big Bang expansion is beyond our capacity to comprehend.

American astronomer Jill Tarter, who has been involved in the SETI project since the beginning, puts the challenge into perspective .

“If you build a mathematical model, the amount of searching that we’ve done in 50 years is equivalent to scooping one eight-ounce glass out of the ocean, and then looking to see if you caught a fish … We just haven’t searched very well yet.”

Land-based intelligent life is rare

In the best of circumstances, looking for life using the methods of SETI would be like searching for a needle in a haystack. But if, say, only one percent of planets capable of producing life actually do so, and if only a fraction of those planets develop advanced intelligence, the odds of SETI succeeding might be vanishingly small.

And what if most of the intelligent life in the universe is water-based? Limited by environmental circumstances, intelligent oceanic life forms wouldn’t be sending out or receiving radio signals.

Star Trek fans will certainly remember the plot of “Star Trek IV: The Voyage Home,” when the safety of Earth was inadvertently threatened by an alien probe seeking contact with humpback whales. It apparently never occurred to these aliens that intelligent beings might be based on land rather than water.

Other advanced civilizations may have moved beyond radio technology

Radio is a 20 th century technology on the verge of being phased out in favor of digital communications. If the use of radio represents a brief interlude for advanced civilizations, it might not occur to alien civilizations to advertise their presence using radio frequencies. SETI was itself conceived in the 20 th century, and its radio-centered approach may be a product of its times.

“In a lot of ways, SETI is a bit of a mirror back on ourselves and our own technology and our understanding of physics,” Dennis Price admits .

The development of human society is out of sync with the rest of the universe

Even if we aren’t unusual, perhaps the pace of our technological development is.

Perhaps our civilization rose to prominence either long before or long after other advanced civilizations developed (or will develop) in the Milky Way. If either is true, we may be looking for signals that were sent out eons ago and have long since faded; or conversely, we may be looking for signals that won’t be sent until a few thousand years in the future.

Fear of the unknown

A society that beams optical or radio signals into space would be announcing its existence and location to any and all parties intercepting the message.

In a benign universe, this might be perfectly okay. But in a universe filled with violent predators, sending out such signals could be an open invitation to invasion and enslavement. Other advanced civilizations might not be willing to take that risk, and that may be why the universe is currently observing radio silence.

Government cover-ups

If SETI ever did find confirmation of intelligent life, how can we be sure they’d tell us?

In 1960, a U.S.-based think tank called the Brookings Institute issued a report that discussed the impact alien visitation or detection might have on human society.

“Anthropological files contain many examples of societies, sure of their place in the universe, which have disintegrated when they have had to associate with previously unfamiliar societies espousing different ideas and different ways of life,” the report cautioned. “Others that survived such an experience usually did so by paying the price of changes in values and attitudes and behaviour.”

For years, rumors about SETI cover-ups have run rampant in conspiracy and UFOlogical circles. Supposedly, SETI has found proof of alien life numerous times, but has not been allowed to reveal the truth to the public. Shadowy government agencies are usually responsible for issuing these gag orders, according to conspiracy theorists, who often attribute their claims to mysterious inside sources.

SERENDIP and the Wow! Signal

For a SETI-detected signal to be accepted as legitimate, it must be both anomalous and repeatable. No signal that meets the second requirement has ever been found. However, something extremely mysterious and anomalous was discovered on one well-documented occasion.

The Berkeley SETI Research Center, which is sponsored by the Astronomy Department at the University of California-Berkeley, is involved with another SETI initiative that traces its origins back to the 1970s. This program is called SERENDIP (Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations), and it is run by researchers who analyse radio data collected by astronomers at telescopes all across the United States.

SERENDIP continues to this day, and while it has not found any definitive evidence of anything it did have one apparently remarkable “hit” back in 1977. On August 15, a 72-second radio emission with highly unusual characteristics was picked up by astronomers working at Ohio State University in Columbus, Ohio. This so-called “Wow!” signal emerged from the constellation Sagittarius, and its content carried several markers that seemed to suggest intelligent design.

The Wow! signal was unexplained at the time and remains so today. However, all attempts to find it again have failed, and that lack of repeatability has kept it from being accepted as definitive proof of alien contact.

Alternative explanations have been found wanting as well, and that makes the Wow! Signal a riddle that defies logical explanation—which makes it a good metaphor for the SETI quest as a whole.

There’s good reason to believe intelligent life is out there, most likely in abundance. But our long search for conclusive evidence of its existence has proven futile. Why it should be that way is the riddle, and until ET lands on the White House lawn or on the grounds of Buckingham Palace all we can do is wait and wonder.

Top image: SETI telescope at night. Credit: sdecoret / Adobe Stock

By Nathan Falde