Neutrinos have mass.
みんな書いていますが，2日連続の快挙にびっくりです。物理学賞，受賞の理由はNeutrinos have mass.という一文で表すことができます。have massは「質量がある」ということで，従来の定説であったニュートリノには質量がない（massless）を実験から否定したということです。（Bua）
Takaaki Kajita and Arthur McDonald Share Nobel in Physics for Work on Neutrinos
Takaaki Kajita of the University of Tokyo and Arthur B. McDonald of Queen’s University in Canada were awarded the Nobel Prize in Physics on Tuesday for discovering that the ubiquitous but elusive subatomic particles known as neutrinos have mass.
Neutrinos are the second most abundant subatomic particles in the universe, after photons, which carry light. Their existence was predicted in 1930, but for decades they remained some of the most enigmatic elements of astrophysics.
The ghostly neutrino — it means “small neutral one” in Italian — carries no electric charge and is so light that it had been assumed for many years to have no mass at all. The scientists showed that neutrinos, which are found in three “flavors,” could oscillate from one flavor to another — changing identities like a spy on the run, as they traveled through the atmosphere or through space from the sun — demonstrating that they have mass.
Dr. Kajita was part of a team of researchers who in 1998 discovered that neutrinos from the atmosphere switched between two identities on their way to the Super-Kamiokande detector, nearly two-thirds of a mile below the earth’s surface.
