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 does it
mean? We asked physicist Silvia Pascoli at the U.K.’s Du