Neutrino finding could explain why there is matter in the universe

Japan’s "T2K," one of our favorite neutrino experiments (we’re keen on several), might have just cracked the mystery of why matter triumphed over antimatter after the Big Bang (they should have canceled each other out). The international experiment’s data from earlier this year--before its science was interrupted by the earthquake in March--indicates that muon neutrinos can transform into electron neutrinos.

A primer on neutrinos and why we should care about them: Neutrinos are one of the fundamental building blocks of matter, though they interact very weakly with normal matter (innumerable neutrinos kicked out by the sun pass straight through the earth at any moment, rarely pausing to interact with the planet). They come in three flavors: muon neutrinos, electron neutrinos, and and tau neutrinos. And for the aforementioned reason they are very hard to detect.

Nonetheless, via detectors like T2K (for Tokai-to-Kamioka, as these are the origin and terminus of the nearly 200-mile experiment) we are able to detect and study neutrinos every now and again. T2K fires a beam of muon neutrinos straight through the ground from Tokai on the east coast to the Super-Kamiokande detector 183 miles away. And recently at Super-K, some of the neutrinos detected were electron neutrinos, indicating that they has had shifted mid-flight.

We already knew about two different oscillations (that’s a change from one flavor of neutrino to another) but we’ve never this new, third oscillation: a muon turning into an electron neutrino.

This is significant, because it means that normal neutrinos could have different oscillation characteristics than their antiparticle counterparts (antineutrinos). It’s an example of what physicists term a CP violation, and it could explain why, when all of our models show that the Big Bang should’ve created equal parts matter and antimatter (which would annihilate each other instantly), an excess of matter clearly survived to make up the universe.

That’s big news, but nothing is yet certain. Repairs are underway at T2K’s accelerator, and the experiment will begin churning out data to corroborate (or disprove) the finding later this year.


/Popular Science/