Masatoshi Koshiba
Masatoshi Koshiba
Credit: 首相官邸ホームページ

Occupation: Astrophysicist

Year born: 1926

Research Areas: Neutrinos, Detectors, Particle Physics, Cosmic Rays


"I grew up like a million average people, and I do silly things too!"

Source: The Vega Science Trust


Early Life

Masatoshi was born in Toyohashi, Japan. His dad was in the Japanese army and served in China during World War II. His mum died when he was just three years old. As his father was an officer in the army, Masatoshi was expected to go to military school. A month before the entrance exam he contracted polio which left him very weak, and he was unable to join. He went to school in Tokyo during World War II when frequent bombing devastated the city. He only became interested in physics when one of his teachers doubted him. He studied hard for the next year to prove that he was capable. When he left school he went to Tokyo University to study physics. He then moved to the USA, first to study for his PhD in New York. Masatoshi specialized in looking at cosmic rays, high energy particles which come from space. He then moved to the University of Chicago, before returning to Tokyo.

Career Highlights

Masatoshi began working on neutrinos, tiny particles which were yet to be detected. Scientists thought that these particles would be created within stars during nuclear fusion, but no one had detected them. This led scientists to speculate that they had no mass, which would have been a problem for our understanding of particle physics. Masatoshi helped to build a big detector in an old mine underground in Japan. This detector was filled with saltwater. The saltwater provided lot of particles which the neutrinos could hit. When these collisions happened the detector around the outside of the chamber would measure the energy. Only one in a trillion neutrinos are detected, but Masatoshi was successful in measuring these detections for the first time. This included some neutrinos from a supernova explosion in a nearby galaxy. For this work, Masatoshi won the Nobel Prize in Physics in 2002.


As well as his Nobel Prize, Masatoshi has been given many other awards from several countries including Japan, USA, Germany and Israel.

Other Interests

As a child Masatoshi loved Kendo, Japanese fencing, but after getting polio he was no longer able to do it. Instead, he took to building model aeroplanes.