The 2015 Nobel Prize in Physics has been won by Takaaki Kajita and Arthur McDonald, for discovering how neutrinos switch between different "flavours".
Neutrinos are ubiquitous subatomic particles with almost no mass and which rarely interact with anything else, making them very difficult to study.
Kajita and McDonald made important measurements of their properties using huge instruments in Japan and Canada. They were named at a press conference in Sweden.
Yesterday's annoucement: the Nobel Prize in Physiology or Medicine 2015 was divided, one half jointly to William C. Campbell and Satoshi Ōmura "for their discoveries concerning a novel therapy against infections caused by roundworm parasites" and the other half to Youyou Tu "for her discoveries concerning a novel therapy against Malaria".
The total number of Nobel physics laureates recognised since 1901 is now 201, including only two women.
The physics prize is awarded by the Royal Swedish Academy of Sciences, which also decides on the chemistry Nobel - announced tomorrow.
The first of the 2015 Nobel Prizes, for physiology or medicine, was awarded on Monday by the Nobel Assembly at Karolinska Institutet. It was shared by researchers who developed pioneering drugs against parasitic diseases.
Source: bbc On photo: Kamioka Observatory, ICCR, University of Tokyo.