'Proper time' and the Dirac equation

In the theory of the Dirac equation in quantum mechanics, the Dirac matrix β is taken to connect 'proper time' and coordinate time rates of change of operators. The usual Heisenberg equation for the coordinate time rate of change of an operator then leads to a Heisenberg-like equation for its proper time rate (the 'Hamiltonian' being analogous to the generator of proper time translations in classical mechanics). Certain terms have to be set to zero by the use of the Dirac equation, and this is here justified. The equivalence of the formalisms under these conditions is shown and the method allows some well known results for the Dirac equations to be derived in a comparatively effortless manner. (author)