THE IMPLICIT MEDIUM: THE RELATIONAL REFERENCE FRAME OF LIGHT, GRAVITY, AND THE COSMOS

The speed of light c, derived from Maxwell's equations, is traditionally interpreted as a universal constant of the vacuum. Twentieth-century physics elevated this constancy to a geometric postulate about spacetime. This paper proposes a fundamental reinterpretation: c is not a universal constant of nature, but rather the limiting speed of wave propagation in the resultant field of electromagnetic and gravitational interactions — a field that, by its relational nature, does not constitute a substance, but rather an implicit local reference frame. In the proposed model, the electric permittivity ϵ(E), magnetic permeability μ(B), and gravitational permeability ρ(g) are local vector functions of their respective fields, and the speed of light emerges from the additive combination of these responses: (𝐸,𝐵,𝑔) = 1/√(𝜀 (𝐸) .𝜇(𝐵) + 𝜌(𝑔))The additive inclusion of ρ follows from the independence of the gravitational field relative to the electromagnetic fields. This formulation preserves the successful equations of relativity within their domains of confirmation, but replaces its geometric ontology with a causal physics of the medium, grounded in logic and anchored in observables. By reclassifying c, ϵ0, and μ0 as local field response functions rather than universal constants, the model eliminates three fundamental constants from the edifice of physics — a reduction that satisfies widely accepted criteria of ontological simplicity. The model eliminates the need to postulate an unobservable absolute spacetime, explains the null result of Michelson-Morley through local rest in the dominant gravitational field, and reinterprets stellar aberration as continuous refraction in the field gradient. It also offers a possible kinematic explanation for the Pioneer anomaly — whose thermal interpretation remains the most accepted — and proposes two accessible laboratory experiments: first, a MichelsonMorley interferometer with an intense electromagnetic field in one arm, whose fringe shift is not predicted by standard physics; and second, a Michelson-Morley interferometer placed in linear motion relative to the Earth's surface — that is, relative to the dominant local gravitational field — a configuration that, according to the model, should reveal an anisotropy in the speed of light and directly test the invariance postulate of Special Relativity.