Quantum Substrate Gravity: A Unifying Theory

This is a program statement, not a finished theory. The working hypothesis is that spacetime geometry, the flow of time, and the observer are three descriptions of one thing: the entanglement structure of a single underlying quantum state. I call that state the substrate. The pieces of that picture are not mine. They come from Ryu–Takayanagi, Van Raamsdonk, the HaPPY code, Jacobson’s entanglement equilibrium, Verlinde’s emergent gravity, Page–Wootters, and Connes–Rovelli thermal time. What is mine is the work of trying to make that premise produce numbers, and then telling the truth about which numbers came out and which did not. Every section is stamped. Established means other people’s results, cited. Derived means I did the calculation and deposited a check. Proposed means I hold the claim and cannot yet derive it. Philosophical means no measurement bears on it. Derived results: a local-temperature formula for an accelerated observer in ΛCDM that generalizes Deser–Levin, 4π²T² = α² + c²(Λ − 2H²); a no-go theorem that no-signaling forbids any non-affine property of a subsystem’s state from sourcing geometry, while leaving that subsystem’s own time free to depend on its state; and a nuisance-marginalized SPARC analysis that excludes the prescribed normalization of the 2017 quantised-inertia galaxy law and fixes a wide-binary benchmark for Gaia DR4. I withdraw three earlier claims: the derivation of a₀ = cH₀/6, the dimensional prediction a₀ = cH₀/2D, and a₀ ∝ H(z). The program does not replace dark matter, does not give observers a role in galactic dynamics, and does not derive a₀. Code, symbolic checks, and the SPARC reproducibility package are deposited with this record or as related records. Errors are mine.