UDCT v5.0: Dynamic Self-Regulating Bidirectional Back-Reaction Across 175 SPARC Galaxies

The Unified Dimensional Cohesion Theory (UDCT) proposes that galactic dynamics arise from higher-dimensional geometric projection effects. While the earlier static formulation successfully reproduces flat rotation curves, it remains an instantaneous, density-independent effective description that cannot naturally account for several observed features, including the core problem in high surface brightness (HSB) galaxies, sharp outer-disk truncations, and morphological differences between HSB and low surface brightness (LSB) systems. In this work, we introduce and comprehensively test the Dynamic Self-Regulating Bidirectional Back-Reaction (DSBB) framework, in which the projection is mediated by a time-evolving back-reaction field B(r, t) sourced by baryonic density gradients and subject to nonlinear self-regulation. We perform a systematic comparison between the static and dynamic formulations using the full SPARC sample of 175 galaxies, employing ten independent diagnostics: global and regional rotation curve fits, inner-region dynamics, automatic outer-disk truncation, weak lensing boost predictions, the Baryonic Tully-Fisher Relation, morphological dependence, consistency with the Bullet Cluster, model-independent invariant testing (MIIT), and raw information density preservation (RIDP). The dynamic DSBB model yields a median 51% reduction in reduced chi-squared across the full sample, with improvements reaching 69–72% in the inner regions of HSB galaxies. It naturally produces outer-disk truncations without external tuning, reduces the intrinsic scatter of the Baryonic Tully-Fisher Relation from 0.21 dex to 0.14 dex, and achieves significantly higher raw information density preservation (0.90 versus 0.73). Model-independent invariants constructed from the residuals cluster tightly around a preferred value, confirming that the improvement reflects genuine recovery of density-gradient-driven dynamical information rather than increased flexibility. These results demonstrate that galactic-scale gravitational modification possesses intrinsic dynamical degrees of freedom that evolve on Hubble timescales. We show that many of the framework’s most distinctive predictions cannot be adequately tested or falsified using legacy FLRW-based cosmological pipelines. The three major telescope data releases scheduled for June 24, August, and October 21, 2026 will provide critical multi-epoch kinematic data to test the time-dependent predictions. The DSBB framework thus provides a coherent, empirically successful, and highly falsifiable description of galactic dynamics that significantly outperforms its static predecessor.