Mass, Gravity, and the Equivalence Principle: An Ontological Derivation from Layered Reality Theory

What is mass, and why are its inertial and gravitational expressions identical? This paper argues that both questions have the same answer. Within Layered Reality Theory (LRT), mass is a base-layer property whose macro-layer expression is the degree of an entity's participation in the coherence constraint structure that constitutes spacetime. Gravity is not a force but the consequence of differential rates of temporal accrual across regions of varying coherence constraint density. The equivalence of inertial and gravitational mass follows as a necessary consequence: both measure depth of coherence constraint embeddedness from different perspectives. They cannot be different because they are not different things.