TAKAYAMA, JAPAN -- An underground facility in Japan has recorded the most convincing evidence yet that the ephemeral subatomic particle called the neutrino has mass. Although the actual mass has yet to be determined and is likely to be a minute fraction of that of the electron, most scientists agree that the findings will force a revision in the Standard Model, the established theory of particles and forces that has served as the basis of modern physics. The results may also affect calculations of the mass of the universe, which would have implications for understanding its origin and eventual fate.