Jimmy Neutron is a boy genius and way ahead of his friends, but when it comes to being cool, he's a little behind. All until one day when his parents, and parents all over Earth are kidnapped by ...

He called it a neutron, and imagined it as a paired proton and electron. There was no evidence for any of these ideas. Chadwick kept the problem in the back of his mind while working on other things.

The neutron plays a fundamental role in the universe and its discovery was at the heart of developments in nuclear physics in the first half of the 20th Century. Prof Val Gibson tells Melvyn Bragg ...