Interaction as Coherence Gradients in the Aether Physics Model: Exact Discrete Corrections, Density-Weighted Radial Measure, and Unified Force Structure

Interaction as Coherence Gradients in the Aether Physics Model extends the Aether Physics Model (APM) and Quantum Measurement Units (QMU) framework by deriving physical interaction from spatial variation in volumetric–chronovibrational structure. Previous work established volumetric coherence as a substrate invariant of the Aether unit and identified subatomic particles as localized activations of this structure through mass-string confinement. The present work develops interaction as a direct consequence of coherence gradients within that same substrate. The fundamental quantity is volumetric coherence, = C³{Fq²}, the invariant relationq C = c, spatial extent and chronovibrational frequency. A response law is introduced in which acceleration arises from the gradient of volumetric coherence, = - \, (voco), interaction as a substrate-level response rather than an independent field. From this formulation, gravitational, electrostatic, and magnetic phenomena emerge as scale-dependent expressions of a single underlying structure. Large-scale coherence gradients correspond to gravitational behavior, localized charge activation produces electrostatic effects, and dynamic or rotational gradients correspond to magnetic interaction. A discrete spherical-shell treatment of the Aether substrate yields an exact closed-form correction to inverse-square interaction. This correction is expressed equivalently as a modified interaction law, a density-weighted radial measure, and a scalar radial density potential. These forms are shown to be mathematically equivalent and to arise from the same coherence-gradient structure. The analysis produces a first-order discrete correction, an exact closed-form solution from quantized shell geometry, an effective radial metric element associated with substrate density variation, and a corresponding radial density potential. Order-of-magnitude estimates indicate that deviations from classical inverse-square behavior are negligible at macroscopic scales but become significant as distance approaches the Compton scale, with nanometer separations providing the most accessible experimental regime. A central result is the unification \;\; density weighting \;\; metric structure \;\; (voco), that force, spatial measure, and potential structure are complementary expressions of a single volumetric–chronovibrational substrate. The work maintains the QMU convention of using the full electron Compton wavelength, \C = hmₑ c, explicit geometric and cyclic closure within the Aether framework. This manuscript is prepared for archival distribution through Zenodo as part of the AetherPhysics research collection.