The Royal Swedish Academy of Sciences said the two researchers had made key contributions to experiments showing that neutrinos change identities as they whiz through the universe at almost the speed of light.
Under the quirky rules of quantum physics, the identity shift the scientists observed can only happen if neutrinos have mass.
Physics Nobel Prize goes for proving Neutrinos aren’t massless. Neutrino oscillation is the process by which neutrinos switch between the three primary flavours: electron neutrinos, mu neutrinos and tao neutrinos. Arthur McDonald of Queen’s University in Kingston, Canada, led the team working with the Sudbury Neutrino Observatory (SNO) in a mine in Canada that confirmed and expanded on the Super-Kamiokande result in 2001.
The University of Tokyo said in a statement congratulating Kajita that he was one of the students of 2002 Nobel physics victor Masatoshi Koshiba, who also has contributed to Japan’s neutrino research. Of all the known elementary particles give the neutrinos to the greatest puzzles.
While Kajita and fellow laureate Arthur McDonald discovered that different types of neutrino have a different mass, they have only been able to determine the difference relative to each type.
Next to particles of light called photons, they are the most abundant particles in the Universe. But when measurements were done on earth, it appeared that two thirds of the neutrinos were missing.
Asked what other questions about neutrinos remain to be answered, McDonald said that scientists would like to know what the actual mass of the neutrino is. They come from a variety of sources in the cosmos, on Earth and in Earth’s atmosphere.
Physicists created the minuscule neutrino particles in nuclear reactions, similar to those that occur in the sun, in the stars, or in nuclear power plants, the Associated Press noted.
Intense activity is underway to understand more about the elusive particles.
Kajita, who initially told a news conference at his university that “my mind has gone completely blank”.
Guido Drexlin, a neutrino expert at the Karlsruhe Institute of Technology in Germany, recalls the day Nobel laureate Takaaki Kajita presented his findings to the science world, in 1998. According to the standard model of physics – the theory that describes the structure of matter – they have neither mass nor electric charge.
Kajita, born in 1959, and McDonald, born in 1943, will share a prize of 8 million Swedish Krona, or almost $1 million.
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 prize for medicine was awarded on Monday to three scientists for their work in developing drugs to fight parasitic diseases including malaria and elephantiasis.
In the coming days, the Nobel committee also will announce prizes in chemistry, literature, peace and economics.