Quantum electrodynamics (QED) is a complex and highly mathematical theory regarding the interaction of electromagnetic radiation with matter. The development of QED theory was essential in the verification and development of quantum field theory and it allows physicists to predict how subatomic particles are created or destroyed. QED is a fundamentally important scientific theory that accounts for all observed physical phenomena except those phenomena associated with aspects of general relativity theory and radioactive decay. QED is compatible with special relativity theory and special relativity equations are incorporated into QED equations. QED is also termed a gauge-invariant theory because its predictions are not affected by variations in space or time.

The practical value of QED theory is that it allows physicists to make calculations regarding the absorption and emission of light by atoms. In addition, QED provides very accurate predictions regarding the interactions between photons...