Feynman Diagrams - definition - Quantum Electro-Dynamics and Quantum Field Theory

Definition: Named for their creator, Richard Feynman, they are part of a method of caculating the interactions between elementary particles (in scattering experiments at high energy electron accelerators, for example) by breaking the total process down in to seperate diagrams, each describing a possible way that the interaction could proceed, combined according tothe rules of quantum mechanics. Although these diagrams quickly become very complicated to calculate as more possible interactions are included, the more complicated diagrams usually contribute smaller and smaller amounts to the final answer, so for a given degree of approximation, one can stop calculating at the equivalent degree of complexity.