Delta-c Mechanics is a field free particle based alternate approach to the physical interaction between mass and photons by way of the Feynman action path probabilities, offering a new approach to mechanical dynamics, and particle structure. It is based on the Feynman view of QED that photons going from one point to another follow all paths and there is a probability that the particles actually exist on those paths. Additionally photon densities moving in one direction retard opposite moving photons and thus create a change in c, as a result of their presence.

Delta-c Mechanics starts with Feynman's action paths and continues a particle based theory. It extends Feynman's presumption in that there is an actual probability of the Feynman path photons being on these paths. This is evidenced by measurements of the Anomalous Magnetic Moment and the Aharonov-Bohm effect. It is presumed that photons taking the action path, not only have delays but the probability density of these photons being there, affecting the speed of light and the motions of other particles.