The Geometric Antinomy of the Hubble Constant: An Effective Framework for Resolving Cosmic Acceleration via UDCT v2.8

This paper reveals a profound antinomic irony at the heart of modern cosmology. By reinterpreting the Hubble constant not as a kinematic expansion velocity but as a geometric relaxation timescale arising from higher-dimensional back-reaction, the Unified Dimensional Cohesion Theory (UDCT) v2.8 demonstrates that the empirical foundation used to establish the Big Bang can be consistently understood without requiring physical spacetime expansion itself. The apparent late-time acceleration is recast as a geometric screening effect, offering a resolution to the Hubble tension while rendering both dynamical cosmic expansion and dark energy conceptually unnecessary. In this framework, the Hubble tension and the necessity of the Big Bang expansion are not separate problems but are simultaneously resolved through the same geometric reinterpretation of H₀. The work is presented as an effective phenomenological model. A rigorous first-principles derivation from the higher-dimensional bulk geometry remains the subject of future investigation.