  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. in technical terms, qed can be described as a perturbation theory of the electromagnetic quantum vacuum. richard feynman called it "the jewel of physics" for its extremely accurate predictions of quantities like the anomalous magnetic moment of the electron and the lamb shift of the energy levels of hydrogen. ==history==   the first formulation of a quantum theory describing radiation and matter interaction is attributed to british scientist paul dirac, who (during the 1920s) was first able to compute the coefficient of spontaneous emission of an atom.  dirac described the quantization of the electromagnetic field as an ensemble of harmonic oscillators with the introduction of the concept of creation and annihilation operators of particles. in the following years, with contributions from wolfgang pauli, eugene wigner, pascual jordan, werner heisenberg and an elegant formulation of quantum electrodynamics due to enrico fermi,  physicists came to believe that, in principle, it would be possible to perform any computation for any physical process involving photons and charged particles. however, further studies by felix bloch with arnold nordsieck,{{cite jo
Concepts_in_physics Electrodynamics Freeman_Dyson Particle_physics Quantum_electrodynamics Quantum_electronics Quantum_field_theory