Clocks and Chronogeometry: Rotating Spacetimes and the Relativistic Null Hypothesis

Abstract

Abstract Recent work in the physics literature demonstrates that, in particular classes of rotating spacetimes, physical light rays in general do not traverse null geodesics. Having presented this result, we discuss its philosophical significance, both for the clock hypothesis (and, in particular, a recent purported proof thereof for light clocks), and for the operational meaning of the metric field. 1Introduction2Fletcher's Theorem2.1Maudlin on the clock hypothesis in special relativity2.2Fletcher’s result in special relativity2.3Fletcher’s theorem in general relativity3Electromagnetism and the Geometrical-Optical Limit 3.1Maxwell’s equations in curved spacetime3.2The geometrical-optical limit3.3Rotating spacetimes3.4Aren’t Gödel spacetimes unphysical?4The Clock Hypothesis and Chronogeometry 4.1Natural and mathematical observations4.2Clock registry discord4.3Chronogeometry5Conclusion