This model was a centrepiece of what has become known as the old quantum theory, which itself was the product of a realization at the turn of the twentieth century that the precepts of classical ...

Philip Ball looks at how a little-known paper by Niels Bohr demonstrates the turmoil in physics on the brink of quantum ...

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 ...

That light can be both particles and waves is one of the most illogical—but at the same time fundamental—characteristics of quantum mechanics. This is called wave-particle duality. The theory ...