Energy Path Freedom and Gravitational Coupling

Energy configurations are organized into three regimes of relative dominance: a free/null radiative reference, an intermediate non-null regime, and a confined or bound regime. The ordering variable is not coordinate speed. It is an operational measure of admissible future-directed null paths determined by the spacetime metric, the physical fields, a declared observer, a domain, and a target boundary. Local photon propagation remains null: in any local inertial frame a photon satisfies ds² = 0 and travels at c. Light is electromagnetic radiation, and radiation carries stress-energy and gravitates. The accessibility descriptor is the observer-conditioned functional P[gμν, uμ, Ω, Σ, μ], defined as the invariant solid-angle fraction of the observer’s local celestial sphere whose future-directed null geodesics reach a preregistered target Σ. P is not proposed as a new scalar field of spacetime. On a static spherically symmetric surface, the Synge escape cone reduces to a function of compactness alone, Pcone = Ψ(C), providing a general-relativistic null control. On the restricted equatorial zero-angular-momentum Kerr construction, matched circumferential compactness does not fix P. At C = 0.250, the equatorial calculation gives P(a* = 0) = 0.698 and P(a* = 0.98) = 0.947. The full-sky zero-angular-momentum-observer implementation, including Carter motion, preserves a smaller but nonzero spin-dependent difference: P(a* = 0) = 0.697642 and P(a* = 0.98) ≈ 0.72658. Independent numerical methods agree at the registered anchor within approximately 3 × 10⁻⁵. These results validate a numerical general-relativistic accessibility calculation; they do not constitute observational confirmation of the three-regime hypothesis. The primary empirical question is whether the full-sky accessibility functional adds grouped held-out predictive information about independently constructed compact-star response observables—including binding energy, tidal deformability, normalized moment of inertia, and quadrupole—beyond rich conventional and universal-relation baselines. The comparison is sign-neutral and includes response-specific leakage controls, nested grouped validation, negative controls, and explicit failure conditions. The rotating compact-star predictive gateway and observational catalog tests remain open.