Neutrinos are often called “ghost particles,” and for good reason. Neutral in charge and tiny in mass, neutrinos are incredibly elusive and mostly pass unnoticed through ordinary matter, including you and me. In fact, neutrinos, one of physics’ fundamental particles, were once thought to be completely massless.
A recent observation from researchers in Italy, however, adds to mounting evidence however that neutrinos do have some – very tiny – mass. Specifically, it was found that neutrinos, which come in three varieties or “flavors,” can spontaneously change their flavor in a process known as oscillation. And because of the nature of quantum mechanics, oscillation only occurs if the flavors have unique masses.