STOCKHOLM — Two scientists won the Nobel Prize in physics Tuesday for key discoveries about a cosmic particle that whizzes through space at nearly the speed of light, passing easily through Earth and even your body.
Takaaki Kajita of Japan and Arthur McDonald of Canada were honored for showing that these tiny particles, called neutrinos, have mass. That’s the quality we typically experience as weight.
“The discovery has changed our understanding of the innermost workings of matter and can prove crucial to our view of the universe,” the Royal Swedish Academy of Sciences said in awarding the prize.
The work dispelled the long-held notion that neutrinos had no mass.
Neutrinos come in three types, or “flavors,” and what the scientists actually showed is that neutrinos spontaneously shift between types. That, in turn, means they must have mass.
Kajita, 56, is director of the Institute for Cosmic Ray Research and professor at the University of Tokyo. McDonald, 72, is a professor emeritus at Queen’s University in Kingston, Ontario.
McDonald told reporters in Stockholm by phone that the discovery helped scientists fit neutrinos into theories of fundamental physics. Kajita, who initially told a news conference that “my mind has gone completely blank. I don’t know what to say,” went on to stress that many people had contributed to his work.





