Neutrinos are real and yet barely detectable. Science estimates 650 trillion of these subatomic ghost particles move through us at nearly the speed of light ever second. Neutrinos were created one second after the Big Bang. They interact so weakly with matter that they can pass through light years of solid lead and not even notice. Why should we care about them, then? There are several possible practical reasons. Because we can occasionally detect them and because we can generate them, there are theories that alien civilizations may be using them instead of radio waves or light to communicate.
Every single second of every single day, you are being bombarded by trillions upon trillions of subatomic particles, showering down from the depths of space. They blow through you with the strength of a cosmic hurricane, blasting in at nearly the speed of light. They’re coming from all over the sky, at all times of the day and night. They penetrate the Earth’s magnetic field and our protective atmosphere like so much butter.
And yet, the hair on the top of your head isn’t even ruffled. What’s going on? …
These tiny little bullets are called neutrinos, a term coined in 1934 by the brilliant physicist Enrico Fermi. The word is vaguely Italian for “little neutral one,” and their existence was hypothesized to explain a very curious nuclear reaction. … Why have we been chasing them for over 70 years, from before World War II into the modern era? Why have generations of scientists been so fascinated by these little, neutral ones?
The reason is that neutrinos continue to live outside our expectations. For a long time, we weren’t even sure they existed. For a long time, we were convinced they were completely massless, until experiments annoyingly discovered that they must have mass. Exactly “how much” remains a modern problem. And neutrinos have this annoying habit of changing character as they travel. That’s right, as a neutrino travels in flight, it can switch masks among the three flavors.
There might even still be an additional neutrino out there that doesn’t partake in any usual interactions — something known as the sterile neutrino, that physicists are hungrily hunting for.
In other words, neutrinos continually challenge everything we know about physics. And if there’s one thing we need, both in the past and in the future, it’s a good challenge.
A long-distance neutrino experiment is taking place under several Midwestern states. A high-energy accelerator, which generates subatomic particles, shoots beams of neutrinos and related particles as much as six miles deep, beneath northern Illinois, across Wisconsin and into Minnesota. The particles start at Fermilab, as part of an experiment called the Main Injector Neutrino Oscillation Search (MINOS). In less than three-thousandths of a second, they hit a detector in the Soudan iron mine, 450 miles away.
The cosmic neutrino background (CNB, CνB) is the universe’s background particle radiation composed of neutrinos. They are sometimes known as relic neutrinos.
The CνB is a relic of the big bang; while the cosmic microwave background radiation (CMB) dates from when the universe was 379,000 years old, the CνB decoupled (separated) from matter when the universe was just one second old. It is estimated that today, the CνB has a temperature of roughly 1.95 K. As neutrinos rarely interact with matter, these neutrinos still exist today.
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. … Neutrinos are produced in large quantities by the sun and astronomical sources, but they can also be produced artificially by nuclear reactors. … the Super-Kamiokande facility, the world’s largest neutrino detector … is located under Mt. Ikeno in Japan. There’s also the IceCube Neutrino Observatory, located at the Amundsen–Scott South Pole Station in Antarctica and operated by the University of Wisconsin–Madison; and the Sudbury Neutrino Observatory, located in a former mine complex near Sudbury, Ontario, and operated by SNOLAB.
… 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.
Who knows what interesting alien chatter we might pick up on the neutrino radio, once we figure out how to really tune in.