Nobel Prize in Physics 2015

The Nobel Prize in Physics 2015 was awarded jointly to Takaaki Kajita and Arthur McDonald “for the discovery of neutrino oscillations, which shows that neutrinos have mass.” Prior to this discovery, scientists knew that neutrinos (really tiny subatomic particles with spin, but no charge) came in three different flavors, but they didn’t know that an individual neutrino could change from one flavor to another.