Canadian scientist Arthur B. McDonald and Japanese scientist Takaaki Kajita have won Nobel Prize in Physics 2015 for their contributions to new discoveries that solved decades-old puzzles related to characteristics of light particles – neutrinos.
The experiments by the two scientists have demonstrated that neutrinos change identities and have mass. A research group in Canada led by Arthur B. McDonald demonstrated that neutrinos from the Sun were not disappearing on their way to Earth. Instead they were captured with a different identity when arriving to the Sudbury Neutrino Observatory (Canada). Meanwhile, Takaaki Kajita discovered that neutrinos from the atmosphere switch between two identities on their way to the Super-Kamiokande detector in Japan.
Takaaki Kajita, a Japanese citizen born in 1959 in Higashimatsuyama, Japan, holds a Ph.D. from University of Tokyo, Japan. Dr. Kajita is currently Director of Institute for Cosmic Ray Research and Professor at University of Tokyo, Kashiwa, Japan.
Arthur B. McDonald, a Canadian citizen born 1943 in Sydney. Dr. Arthur was awarded a Ph.D. 1969 from Californa Institute of Technology, Pasadena, CA, USA. He is currently a Professor Emeritus at Queen's University, Kingston, Canada.
These two discoveries have led to the far-reaching conclusions that neutrinos, which for a long time were considered massless, have some mass, however small. “A neutrino puzzle that physicists had wrestled with for decades had been resolved. Compared to theoretical calculations of the number of neutrinos, up to two thirds of the neutrinos were missing in measurements performed on Earth. Now, the two experiments discovered that the neutrinos had changed identities,” The Royal Swedish Academy of Sciences, which annually confers Nobel Award for Physics, said in an official statement.
The discovery is regarded historic one for particle Physics and has yielded crucial insights into the all but hidden world of neutrinos. After photons, the particles of light, neutrinos are the most numerous in the entire cosmos. “The Earth is constantly bombarded by them. Many neutrinos are created in reactions between cosmic radiation and the Earth's atmosphere. Others are produced in nuclear reactions inside the Sun. Thousands of billions of neutrinos are streaming through our bodies each second. Hardly anything can stop them passing; neutrinos are nature's most elusive elementary particles,” added the Royal Swedish Academy of Sciences.
The Nobel in Physics in 2014 was awarded jointly to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura for the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources.
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