By: Ananya Chakravarthi
The Nobel Prize in physics was awarded this year to Arthur B. McDonald and Takaaki Kajita “for the discovery of neutrino oscillations, which shows neutrinos have mass.” Arthur B. McDonald, a Canadian citizen got his Ph.D. in 1969 from the California Institute of Technology. He is a Professor Emeritus at Queen’s University. Takaaki Kajita, a Japanese citizen, got his Ph.D. in 1986 from the University of Tokyo. He is the Director of Institute for Cosmic Ray Research and Professor at the University of Tokyo. The contributions of Arthur B. McDonald and Takaaki Kajita demonstrate that neutrinos change identities, therefore they must have mass.
Around the turn of the millennium, Takaaki Kajita discovered that on their way to the Super-Kamiokande detector in Japan, neutrinos from the atmosphere switch between two identities.
At the same time, the research group in Canada that Arthur B. McDonald was leading could demonstrate that the neutrinos from the Sun were not disappearing on their way to Earth, but were captured with a different identity when arriving to the Sudbury Neutrino Observatory. This led to the conclusion that neutrinos must have some mass, since before, this was not thought to be so.
Neutrinos are very important in the field of particle physics. Second to photons, they are the most numerous in the cosmos. Created in nuclear reactions inside the sun and in reactions between cosmic radiation and the atmosphere of the Earth, nearly nothing can stop neutrinos from passing–billions of them pass through our bodies every second. The discoveries about neutrinos can improve our understanding of the universe.
