From Michelson–Morley to Sagnac in Causal Lorentzian Theory (CLT) Global Time, Reciprocity, and the Failure of the c±v Interpretation

The Michelson–Morley and Sagnac experiments are often portrayed as being in conceptual tension, leading to claims of ether drift, variable light speeds c±v, or the necessity of a global physical time. This paper shows that such claims arise from conflating coordinate time with physical (proper) time and from elevating kinematic closure relations into physical propagation laws. Within Causal Lorentzian Theory (CLT), spacetime remains locally Minkowskian, light propagates locally at invariant speed c, and observable time differences arise from conformal time scaling and causal holonomy rather than from variable light speed. CLT eliminates global physical time by construction and thereby resolves Dingle-type paradoxes, reciprocity confusions, and the misuse of expressions such as t_±=L/(c∓v). Michelson–Morley probes local inertial structure, while Sagnac reveals the global failure of simultaneity in non-inertial motion. Both experiments are naturally unified within CLT.