Did Physicists Find Evidence of a Fourth Neutrino Flavor?

When neutrinos change from one phase to another, they tell us something about their mysterious nature. These ghostly subatomic particles come in three flavors, physicists say: muon, tau, and electron. Just this summer, a team caught a neutrino in the act of changing from muon to tau, a finding that backed up the argument that these particles do, in fact, have mass. This week, a new study of neutrino oscillation—the changing of flavors—suggests an deeper mystery, and implies that these three flavors of neutrino may not be enough to account for these particles' behavior. In Physical Review Letters, a large group of physicists published their study from the MiniBooNE experiment at Fermilab in Illinois. When the physicists looked at oscillations of muon antineutrinos into electron antineutrinos, they found the process happening faster than known physics predicts. Neutrinos followed the rules, but antineutrinos didn't behave the same way did. So what ...