American physicist Richard Feynman's work and writings were fundamental to the development of quantum electrodynamic theory (QED theory). With regard to QED theory, Feynman is perhaps best remembered for his invention of what are now known as Feynman diagrams, which portray the complex interactions of atomic particles. Moreover, Feynman diagrams allow visual representation and calculation of the ways in which particles can interact through the exchange of virtual photons and thereby provide a tangible picture of processes outside the human capacity for observation. Because Feynman diagrams allow physicists to depict subatomic processes and develop theories regarding particle interactions, the diagrams have become an indispensable and widely used tool in particle physics.

Feynman diagrams derive from QED theory. Quantum electrodynamics (QED), is a fundamental scientific theory that is also known as the quantum theory of light. QED describes the quantum properties (properties that are conserved and that...