Author: Fraser Cain

It’s one of the biggest questions in all humanity: are we alone in the Universe? Either way, the answer is significant. And so, scientists are searching for intelligence out there. Huge arrays of radio telescopes, like the Allen Array scan the skies for radio broadcasts. And researchers have also proposed that aliens might be using lasers to communicate with us. A Russian researcher is proposing another way that aliens might be communicating with us – with neutrinos.

To borrow a quote from the Hitchhiker’s Guide to the Galaxy, “Space is big. You just won’t believe how vastly, hugely, mind- bogglingly big it is.” When you’re attempting to communicate across the vast distances of space, you need huge amounts of energy. Just look at a star, even though it’s generating an incomprehensible amount of energy every second, the brightness drops dramatically with distance.

Instead of broadcasting in all directions, the other strategy is to focus your communications towards a specific location. A targeted beam of radio waves or laser light towards another star still requires an enormous amount of energy, but it’s less.

To save energy, alien civilizations might not be using radio or optical light at all, they might be communicating in a completely different way, with neutrinos.

Researcher Z. K. Silagadze at the Budker Institute of Nuclear Physics and Novosibirsk State University recently posted this idea to the Arxiv pre-press mailing list. His article is called SETI and Muon Collider.

It might sound like science fiction, but scientists are starting to understand how to generate beams of neutrinos – by creating beams of muons. Beams of these unstable particles can be generated in large particle accelerators. The muon beam decays quickly into a focused beam of neutrinos that can travel for light years and still remain remarkably coherent. A beam fired at relatively nearby star Tau Ceti, 12 light-years away, would open up to about 600 astronomical units across – enough to bathe the whole system in neutrinos that could be tracked back to a specific source star.

Finding neutrinos here on Earth is difficult. We’ve got an incredible amount of neutrinos stream towards us from the Sun. In fact, you’ve got billions of neutrinos passing through your body every second and you never feel them because never interact. It takes a huge vat of water, protected underground from other radiation and a suite of sensitive detectors. And even then, they only turn up a few thousand neutrinos a year.

In fact, a neutrino can pass through light-years of pure lead and not even notice.

But there are some advantages. Neutrino detectors are omnidirectional – they don’t have to be targeted in a specific direction to “tune in” a signal coming from a star. If the stream of neutrinos is passing through the Earth, we should be able to detect it, and then track back the source after the fact.

Neutrino detectors are also sensitive to many different energy levels. They don’t have to scan specific frequencies, they can detect high energy neutrinos as easily as low-energy ones.

According to Silagadze, the newly developed IceCube neutrino observatory being built in Antarctica should have the sensitivity to spot neutrinos generated on purpose by alien civilizations – whether they’re targeting us specifically, or we’re just overhearing their conversations.

It has been suggested that advanced civilizations might deliberately choose neutrinos for communications because it shuts out the very young, and not mature civilizations from the galactic conversation.

But give us a few years, and we’ll be listening.

Original Source: Arxiv