In particle physics, the Dirac equation is a relativistic wave equation derived by British physicist Paul Dirac in 1928. In the limit of zero mass, the Dirac equation reduces to the Weyl equation.
Although it is not a successful relativistic generalization of the Schrödinger equation, this equation is resurrected in the context of quantum field theory, where it is known as the Klein-Gordon equation, and describes a spinless particle field.
The specific Clifford algebra employed in the Dirac equation is known today as the Dirac algebra. See Dirac spinor for details of solutions to the Dirac equation. In the limit m 0., the Dirac equation reduces to the Weyl equation, which describes relativistic massless spin- 1⁄2 particles.
Generically, three out of four components of the spinor function in the Dirac equation can be algebraically eliminated, yielding an equivalent fourth-order partial differential equation for just one component.