A Three-Regime Framework for Electromagnetic Radiation: Source, Propagation, and Geometry

This concept paper proposes a conservative organizing framework for describing the physical journey of electromagnetic radiation. Rather than treating radiation as sequential intrinsic transformations of the photon itself, the framework distinguishes three interaction regimes defined by which physical sector most strongly controls observable behaviour: a source-dominated regime at generation, a propagation-dominated regime of approximately free null motion, and a geometry-dominated regime in which spacetime structure becomes the leading influence on trajectories, frequencies, and arrival times. The regimes are not universal irreversible stages that every photon must traverse in fixed order; they are regions of relative dominance that may overlap, reverse, or recur according to the local environment. Radiation is viewed as an information carrier that can imprint successive layers of source physics, propagation effects, and geometric signatures. The framework remains independent of any particular dynamical model of masslessness or inertia. Insights drawn from Universal Exchange Medium Theory (UEMT) are examined solely as one candidate interpretation of the propagation-dominated regime and are not required for the logical structure of the three-regime classification. The paper states explicitly what the framework does not claim, outlines conditions under which it could acquire scientific usefulness, and identifies observational domains in which the classification may organize existing data without modifying general relativity or quantum electrodynamics.