In 2019, astronomers used the Parkes Radio Telescope in Australia to study stellar flares (explosions) on the star Proxima Centauri. They detected a five-hour-long burst of radio waves, which they dismissed as interference. However, a year later, an intern on Yuri Milner’s Breakthrough Listen located a curious signal in the data.
NASA filmmaker and popular science educator Simon Holland has rekindled interest in this signal, Breakthrough Listen Candidate 1 (BLC-1). Now, researchers at Breakthrough Listen are reevaluating it as a potential technosignature, which could be evidence of non-human intelligence.
Breakthrough Listen is one of Giving Pledge signatory Yuri Milner’s Breakthrough Initiatives. Leading the global search for extraterrestrial intelligence (SETI), this project is working through challenges like weak data and Earth-based interference, which complicate verification efforts.
BLC-1’s Possible Origination: Proxima Centauri
BLC-1 is a single-point source. Holland reports that while radio telescopes capture “the giant buzz of everything in the Universe,” this signal has “a narrow electromagnetic spectrum.”
At 983 MHz, BLC-1 is a narrowband signal, which means a known natural source didn’t produce it. As the signal appears to vanish when observations move away from the source, there’s a possibility that it didn’t come from Earth.
Furthermore, when using the Parkes Telescope to analyse the signal, researchers identified a Doppler shift. Over two hours of tracking BLC-1, the signal’s frequency increased and decreased. This suggests that the signal could be orbiting a distant star like Proxima Centauri, which is around 4.2 light years away from Earth.
Scanning Proxima Centauri’s Star System
Researchers at Breakthrough Listen have scanned Proxima Centauri’s star system across several frequencies, ranging from 700 MHz to 4 GHz. This is the equivalent of tuning to more than 800 million radio channels simultaneously.
They identified four million hits, of which they eliminated three million. They then applied another filter to the remaining million hits. Repeatedly pointing the Parkes Telescope at the star and away again left them with 5,160 possible technosignature candidates.
However, research into these candidates suggests that faulty equipment near the telescope may have created the signal.
Excitement piqued again when Breakthrough Listen revisited the signal and found that an automated sorting programme in their filters had overlooked various signals. These signals resembled BLC-1 but were emitted at other frequencies.
That said, the Listen researchers have reported that these frequencies are “consistent with common clock oscillator frequencies used in digital electronics.” This means there’s every chance the signals come from human technology after all.
A Human or an Extraterrestrial Technosignature
In more recent news, the Listen researchers went on to identify additional technosignature candidates. This means that Listen is now examining not only BLC-1, but also BLC-2, 3, 4, and 5, using some of the world’s most advanced telescopes.
Although fascinating, analysis so far once again shows that the signal could have come from local interference with the data. Researchers often find similar radio interferences that turn out to be technosignatures caused by humans. In this case, they have identified other Earth-based signals that BLC-1 closely resembles.
Breakthrough Listen’s Ongoing Research
Funding from Yuri Milner and support from global partners is fueling ongoing research into BLC-1. Although scepticism and technical hurdles remain, the implications of verifying a signal would be profound.
Such a finding would align with Yuri Milner’s vision to explore humanity’s place in the Universe and inspire further investment in cutting-edge research, as discussed in his Eureka Manifesto. This personal manifesto aligns with several of his philanthropic projects, from the Breakthrough Initiatives to the Breakthrough Prize and Breakthrough Junior Challenge.
For now, the weak BLC-1 signal is in the low information zone, which means there isn’t enough data to confirm its origins. Yet.