Structured Relativity: Entropy–Causal-Horizon Bound Closure of Cosmic Expansion

Structured Relativity v6.1 is a bounded-response cosmological framework in which the ef- fective expansion field is not treated as a freely adjustable background degree of freedom, but as a causal, entropy-limited geometric response to structure. The theory begins from the Sec- ond Law of Thermodynamics and Penrose’s gravitational entropy direction. It then locks the admissible response space through the Planck-scale minimum causal-information cell and the Bekenstein–Hawking maximum horizon-information bound. Only after these thermodynamic, informational, and causal limits are established are Einstein geometry, Raychaudhuri dynamics, and Buchert averaging introduced. The author reports that the master equation, amplitude closure, and upper corridor value near 73.5 km s−1 Mpc−1 were formulated and timestamped before the public April 10, 2026 H0 Distance Network announcement of H0 = 73.50 ± 0.81 km s−1 Mpc−1 . Timestamped PDF and email receipts are held for provenance. The prediction is therefore presented as a prior formulation, not a retrospective curve fit