Resolving the Hubble Tension and Dark Matter Anomalies via Osmotic Spatial Decompression in a Closed Thermodynamic Universe

The ongoing gap between the local expansion rate of the universe (H0) and the global rate inferred from the Cosmic Microwave Background has triggered a genuine crisis for the standard ΛCDM model. Most attempts to patch this Hubble Tension rely on early dark energy or modifications to General Relativity—approaches that usually require injecting unconstrained variables into the math. We propose a strictly thermodynamic resolution instead. By modeling the universe as a closed system governed by information conservation, we can redefine Dark Energy. It is not a uniform, static vacuum energy; it is an emergent, dynamic osmotic pressure. When we apply standard fluid dynamics to the local KBC Void (δ≈−0.46), the elevated local Hubble constant (Hlocal≈73.0km/s/Mpc) mathematically drops out of the global baseline (Hglobal≈67.4km/s/Mpc) as a direct consequence of osmotic decompression. Beyond expansion rates, this closed-system boundary establishes a foundational cosmic noise floor. This allows us to derive the MOND acceleration threshold (a0≈1.1×10−10m/s2) from first principles, resolving the Bullet Cluster paradox without the need for collisionless dark matter.