2015 Nobel Prize in Physics

The 2015 Nobel Prize in Physics has been awarded to Takaaki Kajita and Arthur B. McDonald. The prize was announced by the Royal Swedish Academy of Sciences in Stockholm on 6 October 2015.

The citation

The citation reads: "for the discovery of neutrino oscillations, which shows that neutrinos have mass". They share the prize equally.

The laureates

Takaaki Kajita was born in 1959 in Higashimatsuyama, Japan, and is affiliated with the University of Tokyo, Kashiwa. Arthur B. McDonald was born in 1943 in Sydney, Nova Scotia, Canada, and is affiliated with Queen's University, Kingston.

Why it matters

Neutrinos are tiny particles that pass through almost everything. Experiments in Japan and Canada showed that they change from one type to another as they travel, which proves they have mass.

The prize

The prize is worth 8 million Swedish kronor, divided between the laureates. It will be presented at a ceremony in Stockholm on 10 December, the anniversary of the death of Alfred Nobel, the Swedish inventor of dynamite whose will founded the prizes in 1895.