Conventional quantum mechanics defines the wavefunction through its mathematical properties, asserting a connection with the physical world through measurement postulates.  Ontological questions about the origin and  possible existence of physical analogs of wavefunctions  remain unanswered. However, the  Feynman path-integral formulation of quantum mechanics has for many years hinted that paths may provide a connection to a more complete statistical mechanical picture. A barrier to this has been the unknown origin of phase in wavefunctions.

This work starts with Minkowski space where the speed of light is invariant through all inertial frames. This invariance forces sequential  timelike events on a particle's worldline to manifest a form of continuous phase through the restriction that associated lightlike edges in a 1+1 spacetime cannot continuously rotate in the spacetime plane in which they exist. However, they can and do rotate  out of the spacetime plane of the worldline and this rotation forms the basis of the Feynman Relativistic Chessboard model. Noting this behaviour has allowed the Chessboard model to be extended from 1+1 to 3+1 dimensions. It also provides insight into the origin of quantum phase. We shall show that Feynman's propagator for the electron, built within the context of quantum mechanics, may also be built without reference to quantum mechanics by using familiar aspects of spacetime diagrams. Linking the two routes to the same propagator shows that quantum phase is a manifestation of relativistic time dilation.