An approach to directly probe simultaneity

TL;DR

This paper proposes an experimental method to directly test the concept of simultaneity in special relativity, challenging the assumption of differential simultaneity by analyzing clock differences and light speed isotropy.

Contribution

It introduces a novel experimental approach to distinguish between Lorentz transformation and an alternative absolute simultaneity model.

Findings

Published optical tests cannot differentiate the two transformations.

Derived equations show clock differences relate to light speed anisotropies.

Proposed experiment can directly measure simultaneity differences.

Abstract

The theory of special relativity derives from the Lorentz transformation. The Lorentz transformation implies differential simultaneity and light speed isotropy. Experiments to probe differential simultaneity should be able to distinguish the Lorentz transformation from a kinematically-similar alternate transformation that predicts absolute simultaneity, the absolute Lorentz transformation. Here, we describe how published optical tests of light speed isotropy/anisotropy cannot distinguish between the two transformations. We show that the shared equations of the two transformations, from the perspective of the "stationary" observer, are sufficient to predict null results in optical resonator experiments and in tests of frequency changes in one-way light paths. In an influential 1910 exposition on differential simultaneity, Comstock described how a "stationary" observer would observe different clock readings for spatially-separated "moving" clocks. The difference in clock readings is an integral aspect of differential simultaneity. We derive the equation for the difference in clock readings and show that it is equivalent to the Sagnac correction that describes light speed anisotropies in satellite communications. We describe an experimental strategy that can measure the differences in spatially-separated clock times to allow a direct probe of the nature of simultaneity.