Yuri Milner is one of the most visionary tech pioneers in history. He made his billions by helping to fund tech startups like Twitter, Alibaba, WhatsApp, and Spotify.
In 2015, Milner decided to give the Search for Extraterrestrial Intelligence (SETI) community a major boost. From the 1960s on, SETI was the red-headed stepchild of science. The group had to beg, borrow, and steal money to get time on radio telescopes. Nevertheless, they developed innovative ways to search for radio signals or other signs of intelligence in the cosmos.
In 1992, Congress authorized $100 million over a 10-year period for SETI research, called the High Resolution Microwave Survey (HRMS). But less than a year later, Congress rescinded the funding, as they should have. This sort of "pie in the sky" research is better funded by private sources.
In 2015, Milner and his Breakthrough Foundation offered the SETI scientists $100 million for research, also over a 10-year period. "Breakthrough Listen" promised to be the most comprehensive, intensive, and careful search for extraterrestrial life in history.
It's been more than 10 years now. What have they accomplished?
Obviously, they were not successful in finding alien life. But the techniques they developed in the search will define SETI for the next several decades. The money also helped recruit and train a new generation of SETI scientists.SETI is no longer the joke it was in previous decades, as more young people are willing to choose a career looking for life elsewhere.
The original goals of the program were ambitious.
"Over an initial 10 years, they would conduct long, sensitive observations of several thousand of the closest stars," writes Keith Cooper of Supercluster. "They would perform a less intense survey of another million stars, and in general listen for signals along the plane of the Milky Way and towards the galactic center, which is the direction in which most of our galaxy’s stars can be found."
To make all this possible, they would book time on the largest radio telescopes, broaden the search to encompass optical laser signals as well as radio, extend SETI from its traditional California base to the rest of the world, adopt new techniques and enlarge the community while training the next generation of SETI scientists. Indeed, at the launch of Breakthrough Listen, Milner talked about introducing a fundamental change in how SETI is done, describing how it would “bring the Silicon Valley approach to the search for intelligent life in the Universe,” and that “Our approach to data will be open and taking advantage of the problem-solving power of social networks.”
Even this statement, just 11 years old, has become dated. Back then, the approach to sifting through big data was citizen science, but in the years since, machine learning and artificial intelligence have seen breakthroughs that the SETI community, and indeed the astronomical community at large, have utilized.
"However, it has been the third, most recent, era that has seen one of the most important developments: the introduction of all-sky, all-the-time commensal SETI on the Low Frequency Array (LoFAR) in Western Europe, at the Westerbork Observatory in the Netherlands, and on MeerKAT," writes Cooper.
"Commensal SETI" piggybacks on data being collected by telescopes that are actively conducting routine astronomy for other purposes. When a major radio telescope (like the Very Large Array in New Mexico or MeerKAT in South Africa) points at the cosmos to study galaxies, pulsars, or star formation, a duplicate copy of the digital data feed (a "data spigot") is split off and sent to specialized SETI processors. Systems can comb through millions of narrow radio channels simultaneously without interrupting the primary astronomers.
In short, it treats the rest of the astronomical community's normal observation schedule as a massive, free-flowing stream of raw data to hunt for technosignatures.
Astronomers at Breakthrough Listen want to use Commensal SETI to conduct an "all-sky, all the time" approach to SETI. "What’s needed for all-sky, all-the-time SETI is an array of smaller wide-field telescopes that can combine to provide great resolution across a large swathe of sky," says Cooper. "To that end, Breakthrough Listen has moved to deploy commensal SETI experiments on arrays such as LoFAR and MeerKAT, the latter with an eye on scaling up the experiment for the full Square Kilometre Array-Mid when it comes online in the early 2030s."
The commensal SETI experiment on MeerKAT is called BLUSE, standing for "Breakthrough Listen User Supplied Equipment." “We have our own back-end on there [BLUSE] that is picking out individual targets in the field of view,” says Steve Croft, a Breakthrough Listen radio astronomer. “Someone can be using the facility to look at a pulsar, and we can tick off a few SETI targets that are also in the field.”
All-sky surveys do produce a lot of data, and handling all that raw information is challenging. MacMahon explains that the team originally planned to ship data from telescopes on hard disks, but this quickly proved impractical, and now all Breakthrough Listen data is downloaded over the Internet. It feels like the rest of the astronomical community has really been playing catch-up with SETI in recent years in terms of embarking on large surveys, big data and anomaly detection, all facilitated by machine learning and allowing the two communities to dovetail in their interests and specialities.
Perhaps most importantly, Breakthrough Listen has taught SETI scientists to manage expectations about finding alien life as scientists enter the next phase of the search. “What it [Breakthrough Listen] has done is place new constraints on the prevalence of technology in our galaxy,” says Croft. The old "Drake Equation" that tries to quantify how many alien civilizations there may be in the galaxy was useful in helping us imagine how many inhabited worlds might be out there that we could eventually discover.
"As a predictive tool, however, the Drake equation leaves a lot to be desired since its estimates for the number of technological civilizations range from one – us – to a million or more; such is the wide uncertainty in many of its factors," Cooper observes.
We can't tell if we're any closer to finding evidence of ET. But we are systematically "closing the net around our extraterrestrial quarry," as Cooper notes. At least we know that the SETI program will be well funded for many years to come.
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