Repost in celebration of the 2015 Nobel Prize in Physics: Neutrino masses and angles

It was just announced that this year's Nobel Prize in physics goes to Takaaki Kajita from the Super-Kamiokande Collaboration and Arthur B. McDonald from the Sudbury Neutrino Observatory (SNO) Collaboration �for the discovery of neutrino oscillations, which shows that neutrinos have mass.� On this occasion, I am reposting a brief summary of the evidence for neutrino masses that I wrote in 2007.