The 2015 Nobel Prize in Physics has been won by two scientists for a ground-breaking discovery about neutrinos.
The subatomic particles have almost no mass and rarely interact with anything else, making them very difficult to study.
Using enormous machines, Takaaki Kajita and Arthur McDonald found the particles could change form, giving them measurable mass.
Physics is the second of this year’s 800,000 euro Nobel prizes.
They were first awarded in 1901 to honour achievements in science, literature and peace in accordance with the will of dynamite inventor and business tycoon Alfred Nobel.