5D Model of Spacetime: Gravity as Spatial Inflow

General Relativity models gravity as curvature of a 4‑dimensional manifold. While highly successful in weak fields, this geometric interpretation introduces conceptual tensions: it treats time as a coordinate, geodesics in gravitational fields imply retrocausality, predicts singularities, and requires additional unseen components such as dark matter and dark energy. These issues arise from interpreting gravitational time gradients as literal geometric structure.

This paper develops an alternative 5‑dimensional ontology grounded in observed physics. The universe expands at c, implying that space behaves as a volumetric acceleration field with natural units of m³/s². Mass, which does not expand, occupies the next derivative layer with units m³/s. Time emerges as the local ratio between these rates, t = Ṁ/Qm, where Qm = 4πc² is the universal manifold throughput. In this framework, gravity is the inward acceleration of the spatial medium required to maintain causal continuity across mass‑induced rate deficits.

The ontology unifies inertial and gravitational mass as throughput budget and shows that the 5th‑dimensional volumetric acceleration field is not an extra spatial direction but the underlying rate structure that makes gravity, time, causal ordering, atomic organization, heavy‑element formation, and ultimately life itself possible. As the flow approaches uniformity, the model naturally bridges into quantum behavior, where the manifold’s symmetry produces the probabilistic, delocalized states observed in quantum mechanics.