ZIPPED: A Pressure-Based Gravitational Framework Linking Cosmic Expansion to Galactic Dynamics Without Dark Matter

This manuscript presents ZIPPED (Zwanenburg Isotropic Pressure–Driven Dynamics), a pressure-based gravitational framework in which galactic and cosmological dynamics emerge from a coupling between local Newtonian gravity and a universal acceleration scale derived from cosmic expansion. Rather than invoking non-baryonic dark matter, ZIPPED introduces a minimal acceleration threshold associated with the large-scale relaxation rate of spacetime itself. Below this threshold, gravitational behavior transitions smoothly from classical Newtonian dynamics into a pressure-dominated regime, producing flat galaxy rotation curves and baryonic scaling relations without the need for additional matter components. The theory is expressed through a compact closed-form acceleration relation: aZIPPED=aN2+a02,a_{\text{ZIPPED}} = \sqrt{a_N^2 + a_0^2},aZIPPED=aN2+a02, where aN=GMr2a_N = \frac{GM}{r^2}aN=r2GM is the Newtonian acceleration and a0a_0a0 is a cosmologically derived constant linked to the Hubble scale. This formulation ensures continuity, causality, and asymptotic consistency across all distance regimes. ZIPPED differs fundamentally from MOND-like interpolations by providing a physical origin for the transition scale, interpreted as an isotropic pressure floor imposed by cosmic expansion. The framework naturally preserves local gravitational tests while modifying dynamics only where the cosmological pressure term becomes non-negligible. This manuscript consolidates the theoretical foundations, mathematical formulation, transition criteria, and physical interpretation of ZIPPED, positioning it as a falsifiable, minimalist alternative to dark matter hypotheses and modified gravity extensions. Bijscription / Notes (Zenodo “Notes” field) This work is released as a theoretical framework and conceptual foundation.Numerical fitting, observational benchmarking, and cosmological simulations are intentionally separated from the core theory and reserved for follow-up studies. All intellectual property rights to the ZIPPED framework, its formulation, terminology, and conceptual structure are explicitly claimed by the author. Keywords (Zenodo keywords field) gravity galaxy rotation curves dark matter alternative modified gravity cosmology Hubble acceleration pressure-based gravity minimal acceleration ZIPPED Hashtags (voor Zenodo + LinkedIn) #ZIPPED#Gravity#Cosmology#DarkMatterAlternative#ModifiedGravity#GalaxyDynamics#TheoreticalPhysics#FundamentalPhysics