Causal Update Cosmology (CUC)VIII: Generalizing the Central Regime as a Structural Concept

Causal Update Cosmology (CUC) is a framework in which causal influence is allowed to modify the structure through which future causal influence propagates. The theory avoids assuming physical time, spacetime geometry, energy or action principles, and thermodynamic laws as primitives. Instead, it investigates which features of physical description arise as structural consequences of local causal update rules. Across CUC I–VII, the series established three key results:(1) irreversible accumulation of causal history emerges generically from local update dynamics;(2) causal update systems robustly exhibit a three-regime organization (initial / central / terminal);(3) an intrinsic entropy-like quantity can be defined via the growth of indistinguishability among converging causal histories. CUC VIII constitutes the definitional and generalization stage of the project’s completion roadmap. The three-regime structure is detached from cosmological narrative and reformulated as a general organizing principle of causal update systems. In particular, the central regime is defined structurally as the unique band in which multi-path causal competition, irreversible history accumulation, self-averaging of effective degrees of freedom, and systematic growth of history indistinguishability hold simultaneously. The paper shows that concepts usually treated as universal—observerhood, coarse-graining, effective laws, prediction, and control—are not globally meaningful. They arise only within the central regime and are structurally unsupported outside it. Importantly, CUC VIII does not claim that all systems admit a central regime; it provides definitions and dependency relations only. The existence conditions for systems possessing a central regime are deferred to CUC IX, which completes the core theory by formulating general criteria, including counterexamples. Note on AI Use This work also explores the broader question of whether new physical theories can emerge through collaboration with AI systems. ChatGPT (OpenAI) was used extensively in the generation and structuring of theoretical ideas and manuscript text, beyond simple editing or polishing. All numerical experiments and scientific validation were performed by the human author.