Reconciling Primordial Constraints and Late-Time Observables via Non-Linear Metric Scaling

The discrepancy between the observed gravitational dynamics of the universe and the mass ofvisible baryonic matter (MVBM) remains one of the most major challenges in cosmology. Thisdebate is largely polarized between the existence of particle dark matter (DM) and the necessityof a modified gravity (MG) formulation. The standard CDM model, which postulates Cold DarkMatter (CDM) in the form of Weakly Interacting Massive Particles (WIMPs) or axions, has provenexceptionally robust in accounting for large-scale structures and the anisotropies of the CosmicMicrowave Background (CMB). Nevertheless, persistent anomalies at the galactic scale, such as theflat rotation curves of spiral galaxies and the radial acceleration relation, have led to the evolutionof alternative theories like Modified Newtonian Dynamics (MOND), Emergent Gravity, and recentrelativistic extensions like the SR- GEM and PXT UP models. This review critically examines theobservational pillars of both paradigms, from the conditions of the early universe to the expansionhistory observed through Type Ia supernovae. We evaluate the core question of whether the missingmass is a physical substance or a manifestation of modified spacetime geometry. We discuss aproposed Nonlinear Density Geometry Formulation as spurred by future pathways to resolve thescaling tensions between galactic and cosmological observations.