Of the three different neutrinos, each has a different probability of interacting as each of the three flavors. “It is essentially a quantum phenomenon.” “A neutrino particle doesn't just have one flavor, and the chance you’ll see it as a certain flavor comes down to probability,” says Zara Bagdasarian, an assistant project scientist at the University of California, Berkeley. Physicists call this neutrino oscillation. Only when it interacts does it settle on a single one. Similar to how photons travel as waves but interact as particles, each neutrino travels as a probabilistic mix of the three different flavors. Instead of being one thing their whole lives, neutrinos change their type-or “flavor,” as physicists say-as they travel. This should be straightforward, but unlike most other particles, neutrinos are shape-shifters.

These experiments look to see if what interacts with the detector is what scientists expect, based on what they know about the neutrinos coming from the source. Such experiments typically have a well-understood source or a beam of neutrinos in one location and, some distance away, a detector that can identify one or more of the three different known types of neutrinos-electron neutrino, muon neutrino, and tau neutrino. While the answer to the mystery could provide physicists with a better understanding of neutrinos, it might also reveal new insights into the fundamental workings of the universe.Īrtwork by Sandbox Studio, Chicago with Ariel Davis Short-baseline anomaliesĪt the heart of the short-distance miscounts are so-called short-baseline neutrino experiments. This mismatch between experiments and predictions has opened a whole subfield in the study of neutrinos since it was first identified in the early 2000s. Sometimes there are too many of certain types of neutrinos, while in others there are too few. When scientists measure neutrinos in these experiments, the results don’t always match their predictions. One source of confusion has showed up in the results from short-distance neutrino experiments, in which neutrinos are measured after traveling somewhere between a few meters and a kilometer. Since their discovery, they have taunted scientists with bizarre behaviors, some of which physicists have yet to comprehend. These tiny fundamental bits of matter are the second most common particle in the universe yet are anything but ordinary. Of all the known elementary particles, neutrinos probably give physicists the most headaches.

Neutrino particle