General-Relativistic Spacetime from Light-Travel Time Alone

We show that the entirety of 4D general-relativistic spacetime—metric, curvature, and gravitational masses—can emerge from one operational primitive alone: the measured light-travel times between subsystem events. No background manifold, no fundamental matter fields, and no a priori causal ordering are assumed. Curvature and gravitational masses emerge from the failure of these light-travel times—expressed as distances—to embed into Minkowski spacetime. The masses quantify the curvature required to make these distances consistent in a 4D Lorentzian manifold, enabling the framework to derive the corresponding Lorentzian metric. Assuming the validity of a 4D Lorentzian description, the framework predicts the existence of a Minkowski embedding technique that, using distance data consistent with all ranging measurements and after deriving the Lorentzian metric, recovers the observed solar-system planetary masses and orbits. This would provide compelling evidence that spacetime is nothing more than the consistency conditions imposed by measured light-travel times.