A Method for Detecting Vacuum Speed of Light Anisotropy Based on Bidirectional Difference and Rotation-Scanning

The principle of the isotropy of the speed of light is a cornerstone of special relativity and modern physics. However, direct experimental verification of this principle faces a fundamental challenge: the measurement of the one-way speed of light cannot escape the circular logic inherent in clock synchronization, which itself relies on the speed of light. This paper proposes a novel experimental scheme that fundamentally circumvents this dilemma by combining two-way time-of-flight measurements with a rotating baseline scanning method. The core of the scheme consists of the "Bidirectional Difference Method" and the "Clock-Exchange Method". The "Bidirectional Difference Method" eliminates clock synchronization error and resolves the directional dependence of the one-way speed of light by comparing two-way measurement data from specific directions θ and (θ +180°). The "Clock-Exchange Method", by performing measurements with the starting clock positions exchanged along the same spatial path and averaging, obtains a one-way speed of light value that is insensitive to clock synchronization, without requiring any prior synchronization. This paper details the experimental design based on a 10-meter rotatable baseline and high-precision time-interval measurement modules, and provides a signal-to-noise ratio (SNR) estimation. Analysis indicates that this scheme is expected to provide a conclusive result with an SNR exceeding 492:1, offering a pure and powerful test for the principle of the isotropy of the speed of light.