The difficulty – and, for physicists, the fun – starts here. To begin with, there’s no single quantum theory. There’s quantum mechanics, the basic mathematical framework that underpins it ...

Today, it might be turning your computer off and on again. Quantum mechanics — the most successful and important theory in modern physics — is like that. It works wonderfully, explaining ...

Quantum field theory marries the ideas of other quantum theories to depict all particles as “excitations” that arise in underlying fields. The British physicist Paul Dirac started the ball ...