The Metric Accretion-Expansion (MAX) Hypothesis: The Universe as an Active Black Hole Interior

Abstract The Metric Accretion-Expansion (MAX) model proposes a cosmological framework where the observable universe is the internal, expanding volume of a higher-dimensional black hole. This theory reinterprets the event horizon not as a terminal singularity, but as a phase-transition interface. At this boundary, gravitational inflow from an external "parent" manifold is accreted into the localized expansion of internal spacetime. Under this model, the Big Bang is redefined as the initial formation of the event horizon, while the "missing" energy density attributed to Dark Energy is identified as the continuous metric inflow of spacetime from the external domain into the expanding interior volume. This framework resolves the information paradox by treating the universe as an open, non-equilibrium dissipative manifold. By aligning general relativity with a non-singular interior geometry, the MAX model provides a unified geometric solution to the Hubble tension, galactic rotation curves, and cosmic birefringence, suggesting our cosmic architecture is dynamically supplied by an external gravitational environment.