Dark Matter as Inertial Anomaly - Coherence-Depth Dependence of Inertia and the Flat Rotation Curve Problem

We develop an alternative program in which galactic “dark matter” signatures arise from an environmental modification of inertia controlled by the coherence depth of a global ontodynamic background regime F123. Localized structures are modeled as stable coherent regime multiplets Ψ weakly coupled (by Coherent Acti- vation, CoAct) to the background coherence density ρ123(x) via a kinetic coefficient μ(ρ123). A minimal effective field-theoretic dynamics is introduced for Ψ on a background ρ123. Collective-coordinate reduction yields inertial mass automatically as m = R D(Ψ) d3x, with D(Ψ) identified as a positive coherence-stiffness density. We show that coherence-dependent inertia reproduces flat rotation curves, yields the Baryonic Tully–Fisher relation, and implies the Radial Acceleration Relation (RAR) and MDAR. The full observed RAR curve arises from a threshold-saturation universality class for CoAct coupling; the standard exponential form is motivated independently by Poisson-like activation of independent channels. We supply a concrete CoAct toy model in which an ensemble of threshold chan-nels yields μ(ρ123) ∝ ρβ 123 to leading order, and we introduce a minimal dynamical equation for the background F123: a coherence continuity law with activation and dissipation. This turns cluster mergers into in-principle computable events. In particular, the Bullet Cluster constraint is converted into a falsifiable quantitative requirement: cluster-scale mergers must generate coherence-gradient lengths Lρ ∼ 102–103 kpc to reproduce the observed centroid separation. The characteristic acceleration scale emerges from the cosmological coherence gradient, predicting a0 ∼ cH0 without an independent postulate. Conceptually, the mechanism implements the ontology of Metamonism: since perfect isolation is constitutively unattainable, inertia is necessarily relational to the global coherence background.