Polykarp Kusch was a German-born American physicist. In 1955, the Nobel Committee gave a divided Nobel Prize for Physics, with one half going to Kusch for his accurate determination that the magnetic moment of the electron was greater than its theoretical value, thus leading to reconsideration of—and innovations in—quantum electrodynamics.

In particle physics, quantum electrodynamics (QED) is the relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved. QED mathematically describes all phenomena involving electrically charged particles interacting by means of exchange of photons and represents the quantum counterpart of classical electromagnetism giving a complete account of matter and light interaction.