Event Density: One Substrate, Three Domains A Structural Account of Quantum Mechanics, Galactic Gravity, and Universal Soft-Matter Mobility

We present Event Density (ED), a single substrate ontology of discrete events and relational adjacency from which the foundational structures of three nominally separate domains of physics are derived rather than postulated. From substrate primitives alone we obtain: (i) the four foundational postulates of non-relativistic quantum mechanics — Born’s rule, the Schrödinger equation, the Heisenberg uncertainty bound, and the Bell– Tsirelson bound — as forced structural theorems, together with gauge fields, canonical (anti- )commutation, UV-finiteness, and the kernel-level arrow of time; (ii) Newton’s gravitational law with, the MOND transition acceleration, the deep-regime combination law, and the slope-4 baryonic Tully–Fisher relation, all parameter-free; and (iii) a universal degenerate-mobility law that fits diffusion data from ten chemically unrelated soft-matter systems with R2 > 0.986 at a common exponent. The framework predicts no laboratory result that differs from standard physics in the regimes where standard physics has been tested. What it does is replace a long list of independent postulates with a smaller list of substrate commitments, from which those postulates follow as theorems. We tabulate twenty-one forced structural theorems plus one foundational substrate rule, derive the load-bearing results, and close with the framework’s pre-registered empirical falsifiers.