Quantum Mechanics, Electron spin and antiparticles

In 1928 the English physicist Paul A.M. Dirac produced a wave equation for the electron that combined relativity with quantum mechanics. Schr�dinger's wave equation does not satisfy the requirements of the special theory of relativity because it is based on a nonrelativistic expression for the kinetic energy (p2/2me). Dirac showed that an electron has an additional quantum