I Is the Fizeau-Type Experiment Valid for Measuring the One-Way Speed of Light?

[lightarrow]

TL;DR Summary

A Fizeau-type experiment were they claim to be able to measure the one-way speed of light.

Can't see how in this experiment they claim to be able to measure the one-way speed of light:

https://www.researchgate.net/publication/50908639_To_Re-Consider_the_One-Way_Speed_of_Light_UsingFizeau-Type-Coupled-Slotted-Disks

Can you help me to debunk it?

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[Dale]

They seem to have neglected the fact that an anisotropic one-way speed of light will result in a stress-free twisting of the apparatus. This stress-free twisting happens in ordinary relativity in reference frames where the apparatus is translating. But when using anisotropic one-way speed of light then it will happen also in reference frames where the apparatus is not translating, depending on its orientation with respect to the light speed anisotropy.

The authors should have analyzed their results using Reichenbach’s $\epsilon$ or some other similar framework which explicitly supports an anisotropic one way speed of light. Then they could see that their measured results are independent of the $\epsilon$ anisotropy parameter.

Plus, it is researchgate, so does it really need to be debunked anyway?

 

[Ibix]

You can easily measure the one-way speed of light. What you can't do is measure it in an assumption-free way.

I haven't dug much into their paper (a ten year old paper that hasn't found a publisher is not a great sign) but my skim read reached the same conclusion Dale did. The wheels are effectively clocks and are Einstein synchronised in their rest frame. In any other frame or under any other synchronisation convention the rod connecting them is twisted and they are desynchronised.

 

[Ibix]

Incidentally, Marinov (cited in the paper) is criticised in the Experimental Basis of SR FAQ (linked from a sticky thread in this very forum) for exactly this error. These guys seem to be simply repeating it.

 

[Nugatory]

Can you help me to debunk it?

We usually do not allow threads just for debunking crackpottery - if we did , there wouldn't be room for anything else.

We have made an exception for this one as the misunderstanding is common and easily explained. However, now that it has attracted reasonably complete and accurate explanations we can close it. As with all thread closures, if you believe that it is premature and have more to say, you can ask any mentor to reopen it for your contribution.