Motion Without Drift: Completing Einstein's Ether with Space‑Phase Dynamics

Einstein’s 1920 Leiden lecture famously stated that, within general relativity, space isendowed with physical qualities and is therefore unthinkable without a form of ether, whilesimultaneously insisting that the idea of motion may not be applied to this ether. At thetime, this prohibition served a precise purpose: preserving the Michelson–Morley nullresult and rejecting any notion of a detectable ether wind or preferred frame. In this paper,written in a conversational style, we revisit Einstein’s statement in light of modernobservations, including gravitational‑wave momentum transport, gravitational‑wavememory, and runaway black holes (RBH‑1). We argue that Einstein rejected global drift, notinternal dynamics. When space‑phase is understood as a continuous, ubiquitous mediumwhose saturated states constitute matter, relative motion between regions of the mediumbecomes inevitable. Motion is reframed as a transition between conditioned states ofspace‑phase rather than transport through an external background. This view preservesMichelson–Morley, honors Einstein’s caution, and accommodates contemporaryobservations without invoking absolute motion.