Originally Posted by

**Layman**
"No. it doesn't "deviate". You have no clue what a test theory is."

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Heh. Read the wiki article. A few more excerpts:

"An experiment to test the theory of relativity **cannot assume the theory is true, **and therefore needs some other framework of assumptions that are wider than those of relativity. For example, **a test theory may have a different postulate about light concerning one-way speed of light vs. two-way speed of light, it may have a preferred frame of reference, and may violate Lorentz invariance in many different ways.** Test theories predicting different experimental results from Einstein's special relativity, are Robertson's test theory (1949),[1] and the Mansouri–Sexl theory (1977)[2] which is equivalent to Robertson's theory.[3][4][5][6][7] Another, more extensive model is the Standard-Model Extension, which also includes the standard model and general relativity.

Contrary to Robertson, Mansouri–Sexl not only added additional parameters to the Lorentz transformation, but also discussed different synchronization schemes. **The Poincaré–Einstein synchronization is only used in the preferred frame, while in relatively moving frames they used "external synchronization", i.e., the clock indications of the preferred frame are employed in those frames. **Therefore, not only the two-way speed of light but also the one-way speed is anisotropic in moving frames.....

in special relativity the two-way speed of light is isotropic, therefore** RMS gives different experimental predictions as special relativity.** By evaluating the RMS parameters, this theory serves as a framework for assessing possible violations of Lorentz invariance....

In addition to those second order tests, Mansouri and Sexl described some experiments measuring first order effects in v/c (such as Rømer's determination of the speed of light) as being "measurements of the one-way speed of light". These are interpreted by them as tests of the equivalence of internal synchronizations, i.e. between synchronization by slow clock transport and by light. **They emphasize that the negative results of those tests are also consistent with aether theories in which moving bodies are subject to time dilation.**