Quantum electrodynamics

Quantum theory of electromagnetic interactions. These interactions are described via the exchange of carrier particles called photons, for instance: when two electrons repel each other via the electromagnetic force, that influence is transmitted by photons flying back and forth between them.

Quantum electrodynamics is one facet of the standard model of particle physics. It is also the simplest example for a relativistic quantum field theory – a theory that is both a quantum theory and based on the principles of special relativity.