The 2015 Nobel Prize in Physics was won by Takaaki Kajita of University of Tokyo and Arthur B. McDonald of Queens University, Canada, “for the discovery of neutrino oscillations, which shows that neutrinos have mass”.

The Nobel committee's description on the work that has been honored said, "The Nobel Prize in Physics 2015 recognises Takaaki Kajita in Japan and Arthur B. McDonald in Canada, for their key contributions to the experiments which demonstrated that neutrinos change identities. This metamorphosis requires that neutrinos have mass. The discovery has changed our understanding of the innermost workings of matter and can prove crucial to our view of the universe.