The Volumetric Coupling Hypothesis: A Unified Thermodynamic Solution to the Cosmological Constant, Dark Matter, and the Hubble Tension

This paper introduces the Volumetric Coupling Hypothesis, a novel thermodynamic framework proposing that the expansion of the universe is a physical phase transition governed by the equation V = E/ρ_E. We argue that black holes act as "volumetric recycling engines" that convert matter into the vacuum fabric of space-time, providing a structural solution to the Cosmological Constant Problem and the Hubble Tension. By redefining the vacuum as a "stiffened" thermodynamic state, we eliminate the need for exotic dark energy and resolve the 10^120 magnitude discrepancy. Furthermore, by applying this coupling constant to the long-term evolution of the cosmos, this paper predicts a cyclic, oscillatory future. This "Big Bounce" model suggests the universe is a self-regulating thermodynamic engine, avoiding the singularity through a periodic transition between matter-dominance and volume-dominance.