Photon Ontology and Fold Kinematics in a Phase-Transitioning Vacuum: Propagation, Momentum Transfer, and the Relativistic Dispersion Relation as Stability Budget Constraints

This paper develops the ontology of the photon within the Dynamic Principles of the Substrata (DPS) framework, in which the vacuum is modeled as a hyper-elastic continuum admitting three thermodynamic phases. A photon is identified as a propagating phase-transition event: a sub-stable fold that must traverse the substrate at the characteristic speed c in order to satisfy an instantaneous stability condition. From a single stability budget governing all substrate folds, the paper derives: (1) the photon velocity c as an existence condition rather than a kinematic postulate; (2) the proportionality E ∝ f from transverse compression dynamics; (3) bounded photon amplitude, predicting intensity as photon flux; (4) momentum transfer as stability-budget reallocation during absorption; and (5) argues for the relativistic energy–momentum relation E² = (pc)² + (m₀c²)² as a consequence of orthogonal energy channels within the stability budget. Five falsifiable predictions are identified, including anomalous pair-production thresholds near Schwinger-scale fields and substrate-frame anisotropy in cavity QED.