The prize was awarded to Takaaki Kajita and Arthur B. McDonald, the Nobel Committee said Tuesday,
"for the discovery of neutrino oscillations, which shows that neutrinos have mass."
works at the University of Tokyo, in Kashiwa, Japan. McDonald
works at Queen's University, in Kingston, Canada.
The Nobel Committee said the discovery -- arcane to nonscientists -- has changed our understanding of matter, and may yet change our view of the universe.
"The Nobel Prize in Physics 2015 recognizes Takaaki Kajita in Japan and Arthur B. McDonald in Canada, for their key contributions to the experiments which demonstrated that neutrinos change identities," the Nobel Committee's statement said. "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."
A neutrino is "an elementary particle which holds no electrical charge, travels at nearly the speed of light, and passes through ordinary matter with virtually no interaction," according to the physics.about.com
Scientists say that neutrinos, because they interact weakly with other particles, can probe environments that other kinds of energy, such as light or radio waves, cannot penetrate.
Last year's Nobel winners in physics were two scientists in Japan and one at the University of California, Santa Barbara for helping create the LED light
, a transformational and ubiquitous source that now lights up everything from our living rooms to our flashlights to our smart phones.
Since 1901, the committee has handed out the Nobel Prize in Physics 108 times. The youngest recipient was Lawrence Bragg, who won in 1915 at the age of 25. The oldest physics laureate was Raymond Davis Jr., who was 88 years old when he was awarded the prize in 2002.
John Bardeen was the only physicist to receive the prize twice, for work in semiconductors and superconductivity.
In the coming days, the Nobel committee also will announce prizes in chemistry, literature, peace and economics.
On Monday, three scientists shared the Nobel Prize in Medicine
for their work on parasitic diseases.
Swedish industrialist Alfred Nobel created the prizes in 1895 to honor work in physics, chemistry, literature and peace. The economics prize, established in 1968 as a memorial to Nobel, was first awarded in 1969.