For 60 years scientists have been searching the stars for signals that may be artificial in origin – and their hard work may have finally paid off. Astronomers have recently stumbled upon a mysterious radio signal coming from the star closest to the sun, Proxima Centauri. In December of 2020, a yet to be published SETI paper discussing the findings was leaked to the British newspaper The Guardian.
The signal was detected by Breakthrough Listen, a decade-long $100 million venture determined to discover alien broadcasts located at the Parkes Observatory in New South Wales, Australia. Founded in 2015 by Stephen Hawking and Silicon Valley investor Yuri Milner, the project is determined to study the nearest million stars. The researchers were in the midst of analyzing solar flares on Proxima Centauri mid 2019 when they detected the conspicuous signal, which they named BLC-1. 4.2 light years away, Proxima Centauri is the closest star from the Sun. A small red dwarf, it is orbited by at least two planets, one of which may be in the precious “goldilocks zone” – suggesting it is suitable for life. Although tantalizingly close, the 25 trillion-mile journey, 300,000 times the distance from the earth to the Sun, would take tens of thousands of years with current technology.
WHAT MAKES BLC-1 SPECIAL?
Speaking to Scientific American, Jason Wright expressed: “If you see such a signal and it’s not coming from the surface of Earth, you know you have detected extraterrestrial technology, […] Unfortunately, humans have launched a lot of extraterrestrial technology.” GPS, Wi-Fi, and cell towers produces similar signals, making the challenge of distinguishing the most recent findings challenging indeed.
However, a few aspects of BLC-1 stand out. It passed many of the criteria the Breakthrough Listen team checks for to filter out human generated signals. It’s narrow frequency, a characteristic known as “drift”, and the fact it vanished once leaving the telescope’s view are all exciting news. Drift is a slight change in frequency which is associated with the movement of planetary bodies, satellites, or transmitters. The frequency itself, at around 982 megahertz, is an incredibly narrow bandwidth. Andrew Siemion, lead investigator at Breakthrough Listen, describes this significance in Scientific American: “We don’t know of any natural way to compress electromagnetic energy into a single bin in frequency […] for the moment, the only source that we know of is technological.” Although a natural source is unlikely, it cannot be disregarded as a possibility.
BUT WHAT ARE THE ODDS?
Could the nearest star from the Sun truly have intelligent life? Speaking to National Geographic, SETI Institute’s Seth Shostak postulates that if BLC-1 is indeed a signal from an alien civilization, that “there would be more than a half-billion societies out there in our own galaxy—that seems like a lot.” However, there are billions of sunlike stars in the Milky Way, many of which older than the Sun, and most of which likely are to have exoplanets – More than 4,000 exoplanets have been discovered to date.
An updated study from Cal Tech in 2020, influenced by the Drake equation, – used to predict the number of intelligent alien civilizations in the Milky Way – suggests that life on Earth is late to the game. Their findings indicate that the Milky Way may in fact be full of extinct civilizations. Based on updated modeling, they posit that the possibility for intelligent life peaked in the Milky Way 13,000 light-years from the galaxy’s center (due to the highest concentration of sunlike stars) 8 billion years after it emerged. In contrast, Earth sits 25,000 light-years away from the galactic center, having formed 13.5 billion years after the galaxy’s formation. In short – proximate alien life has had a 5 billion head start.
Even at sub-lightspeed interstellar travel seen as plausible in humanity’s near future, the breadth of the Milky Way could be traversed in 5-50 million years – a blip on the cosmic/geological scale. Earth should have already been visited by alien life, yet scientific consensus concludes that we have not.
SO WHERE ARE THEY?
This simple yet profound question puzzled Italian American physicist Enrico Fermi in the 1950’s. Known as “Fermi’s paradox”, the apparent contradiction of the vastness of the universe and the subsequent lack of evidence for intelligent alien life has continued to perplex scientists.
One theory which tries to explain the apparent absence of extraterrestrial civilizations and why they have not contacted Earth is called the “Zoo hypothesis”. The hypothesis postulates that perhaps alien civilizations purposefully hide their existence from humanity in order to preserve our natural state – akin to the “Prime Directive” in Star Trek. This policy is mirrored on Earth regarding isolated tribes. Uncontacted peoples’ in the Amazon and the Andaman Islands are explicitly protected under “no contact” legislation passed by the regions’ respective governments.
However, this hypothesis cannot account for unintended evidence of alien civilizations such as satellites, radio signals, or advanced structures known as Dyson spheres – a hypothetical megastructure used to harness the energy of the stars. As technology exponentially increases in a civilization, it is hard to imagine that an extraterrestrial cosmic footprint could be perpetually held in check. Humanity itself has been leaking radio waves for nearly 100 years.
THE GREAT FILTER
Given the seemingly statistical inevitable fact that alien civilizations do exist – and that they have had a breathtakingly long head start – what on earth is going on? An attempt to finally resolve this mystery is known as “The Great Filter”. Given that there is no evidence of intelligent life other than humanity, one step between the formation of planetary bodies in star systems and advanced technological life must be unlikely.
Posited by Robin Hanson, the steps are paraphrased below:
· A planet capable of harboring life must form in a star’s habitable zone.
· Life itself must develop on that planet.
· Those lifeforms must be able to reproduce, using such molecules as DNA and RNA.
· Simple cells (prokaryotes) must evolve into more complex cells (eukaryotes).
· Multicellular organisms must develop.
· Sexual reproduction, which greatly increases genetic diversity, must take hold.
· Complex organisms capable of using tools must evolve.
· Those organisms must create advanced technology needed for space colonization. (You are here.)
· The spacefaring species must go on to colonize other worlds and star systems, while avoiding destroying itself.
So, the question remains – which step is unlikely? For life to emerge on a planet from chemical molecules – known as abiogenesis – is a good candidate. However, amino acids, the fundamental building blocks of life, have recently been discovered on a passing comet. Another good possibility is the leap from single to multicellular life. Whichever it may be, humanity should hope that this hurdle is behind us.
Given the lack of evidence for aliens, if the “Great Filter” is indeed ahead of human civilization, it can only mean one thing – intelligent beings’ are prone towards self-annihilation. In other words, be careful what you wish for. If the emergence of life is found to be a common phenomenon – whether it be microbes on Mars or an alien civilization habiting the nearest star – that would be bad news. It would suggest that humanity has yet to pass “The Great Filter”.
Author: Liam Penn