Electromagnetic Propagation Through Admissible Spacetime Corridors

This work reformulates electromagnetic propagation as admissible continuation under constraint, making explicit a structural selection principle that is already enforced implicitly by Maxwell theory, General Relativity, and plasma physics but rarely articulated as such. Rather than introducing new dynamics, forces, constants, or ontological claims, the paper demonstrates that physically realized electromagnetic propagation occurs only along constraint-selected spacetime corridors, congruences of characteristics that persist under geometric, boundary, dispersive, and thermodynamic limitations. Formally permissible solutions that fail to satisfy these constraints do not collapse dynamically; they simply fail to continue. The formulation is fully compatible with standard Maxwell equations on curved spacetime, geometric optics, plasma dispersion theory, and relativistic kinematics. The contribution lies in reorganizing these theories to expose a structural admissibility criterion governing which solutions persist as observable phenomena. The framework is empirically anchored across scales using: Near-Earth plasma observations (MMS spacecraft electron distributions and wave ducting), Dispersive electromagnetic propagation in inhomogeneous media, Relativistic astrophysical systems, including the observed coherent wake of a runaway supermassive black hole traversing the circumgalactic medium. The supermassive black hole case provides a macro-scale validation: despite formally allowed alternatives (turbulent dispersion, isotropic mixing), only a narrow, coherent downstream structure persists. This persistence is shown to arise from joint geometric, shock, cooling, and dispersive constraints, exactly the conditions defining admissible continuation. No reinterpretation of General Relativity or electromagnetism is required. Falsification criteria are explicitly stated. The framework fails if coherent propagation persists where constraint analysis predicts unavoidable collapse, or if observed structures violate dispersion- and geometry-imposed admissibility bounds. This work establishes admissible continuation as a necessary structural principle for explaining observed electromagnetic propagation across laboratory, space-plasma, and astrophysical regimes. It restricts, rather than extends, physical interpretation and is intended as a clarifying reorganization of existing physics with direct empirical consequences. Keywords by Domain Electromagnetism electromagnetic wave propagation Maxwell equations geometric optics waveguides dispersion polarization transport General Relativity curved spacetime null geodesics photon spheres event horizons relativistic propagation Plasma Physics plasma waveguiding electron energy shells dispersion relations MMS spacecraft data magnetospheric plasma Astrophysics supermassive black holes circumgalactic medium radiative shocks coherent wakes relativistic plasma flows Mathematical / Structural Physics admissible continuation constraint-selected dynamics congruence stability Raychaudhuri equation persistence under constraint Cross-Domain / Systems scale invariance structural selection falsifiability empirical constraint filtering