In 1928, building on 2×2 spin matrices which he purported to have discovered independently of Wolfgang Pauli's work on non-relativistic spin systems (Dirac told Abraham Pais, "I believe I got these independently of Pauli and possibly Pauli got these independently of me."), he proposed the Dirac equation as a relativistic equation of motion for the wave function of the electron.
En 1928, baseándose en matrices de spin de 2 × 2 que pretendeu ter descuberto de xeito independente do traballo de Wolfgang Pauli en sistemas de espín non relativistas (Dirac díxolle a Abraham Pais: "Eu creo que teño estas de xeito independente de Pauli e posiblemente Pauli as teña de xeito independente de min"), propuxo a ecuación de Dirac como unha ecuación relativista de movemento para a función de onda do electrón.