In 1963, the National Security Agency's Technical Journal (Volume XI, Number 1) featured a classified report with the following conclusion: "We are not alone in the universe."
This is not the opening of a science fiction novel, or the next Spielberg movie.
This is the factual conclusion of the government agency overseeing signal intelligence. The question of whether there is intelligent life in the universe was answered – at least according to the U.S. Government.
The conclusion was not based on hard evidence. It was based on sheer math. Even in our own galaxy, there are 100 million stars with orbiting planets that could support life.
And our galaxy is one of a billion in the observable universe.
The numbers are staggering. As Dr. Frank Drake of the National Radio Astronomy Observatory in West Virginia put it, the question isn't if there is intelligent life out there. We estimate there are at least a billion advanced civilizations that could have arisen by now. The question is, "where is everybody?"
Dr. Drake actually started looking.
In 1960 he began the first systematic attempt to listen for radio signals from extraterrestrial civilizations. That turned into NASA's SETI studies, which added microwaves to the search.
Lately, SETI has added more possible sources, including lasers or optical waves. The more advanced our own civilization gets, the more methods we realize intelligent life might be trying to utilize to talk with us.
The latest theory? Extraterrestrials might use a beam of neutrinos – weightless, uncharged particles – to send communications our way. According to the MIT Press Reader, "While the odds are slim, neutrino technology may be the best – and perhaps only – way to communicate with extraterrestrial civilizations."
Why neutrinos?
- They're fast. They have almost no mass and travel close to the speed of light.
- They're unstoppable. Neutrinos can deliver an unimpeded signal across a crowded universe. Radio waves or light can be absorbed or scattered, but neutrinos can pass through planets, stars, and cosmic dust. Perfect choice for the advanced extraterrestrial to reach out.
- They don't degrade across distance. Electromagnetic waves spread out, especially across interstellar distance. Neutrinos don't.
But an alien civilization trying to reach us using a neutrino beam would have a major problem: It's too advanced for us.
Yes, we have neutrino detectors, but they are only able to capture a tiny fraction of passing neutrinos, not a steady signal. For us, detecting even a single neutrino is an enormous, expensive feat.
There are only a handful of scientific efforts around the world with the resources to detect high-energy neutrinos from space. The IceCube Neutrino Observatory in Antarctica has a massive array of detectors embedded in the ice.
Then there's the Super-Kamiokande: an enormous tank of pure water lined with 10,000 supersized photomultiplier tubes buried 3,000 feet in a mountain.
It looks like something out of a Marvel movie. It cost nearly 400 million dollars to build, in the hope of detecting a single neutrino interacting with a water molecule.
Bottom line, it's hard to detect a particle so elusive it can pass through a planet without hitting anything. There's a reason we call it the "ghost particle".
The one's we do detect are usually from a mundane source: our Sun. The nuclear reactions happening inside the Sun regularly send neutrinos our way. A particle from a planet across the universe would stand out, because it would contain many times the energy of one originating from the Sun.
And in 2023, we found one.
The Cubic Kilometre Neutrino Telescope (KM3NeT) is an array of light collecting glass spheres researchers drop deep in the Mediterranean to detect neutrinos. It's still under construction. But what they have assembled so far actually worked.
In February 2023 astrophysicists detected what they termed "a monster event". The KM3NeT found a neutrino twenty times more powerful than any ever detected.
Neutrinos from the sun contain anywhere from one to ten million electronvolts. The February 2023 particle carried 120 million. This puts it on a level of energy with cosmic rays. The likely source of origination is not our Sun, but a distant galaxy.
No one knows where ultra-high energy neutrinos come from. It could be a black hole, or a stellar explosion. But it could be, with the right receptors, we discover this high energy neutrino was one in a series sent to us with a message.
The researchers in the Mediterranean are getting a bigger array of neutrino detectors. Whatever – or whoever – sent this particle with record-breaking energy has got our attention.
https://www.nature.com/articles/d41586-025-00444-1
https://phys.org/news/2017-06-aliens-neutrino.html
https://thereader.mitpress.mit.edu/are-neutrinos-the-key-to-communicating-with-aliens
https://physicsworld.com/a/neutrino-based-communication-is-a-first