Unified Space Time: A Repulsive Curvature Baseline Postulate

This preprint postulates that, in the low density limit, spacetime is a repulsive curvature baseline, and that attractive gravity is an environmentally suppressed departure from that baseline in dense regions. The postulate is embedded phenomenologically in Einstein gravity using an environment dependent effective vacuum term and is defined operationally using geodesic deviation and Raychaudhuri focusing. A falsifiable test is proposed using stacked deep void weak lensing with an environment dependent void contrast parameter called epsilon void, including explicit null outcomes that would rule out the baseline interpretation. Preprint, not peer reviewed. Intended for submission to JCAP after OSF posting.