this post was submitted on 15 Jun 2024
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[–] [email protected] 1 points 5 months ago (2 children)

If you move one clock very slowly away from the other, the error is minimised, perhaps even to a degree that allows for statistically significant measurements.

To cite the Wikipedia entry that one of the other commenters linked:

"The clocks can remain synchronized to an arbitrary accuracy by moving them sufficiently slowly. If it is taken that, if moved slowly, the clocks remain synchronized at all times, even when separated, this method can be used to synchronize two spatially separated clocks."

One-Way Speed of Light

[–] [email protected] 1 points 5 months ago (1 children)

Except if you continue reading beyond your Quote, it goes on to explain why that actually doesn't help.

[–] [email protected] 1 points 5 months ago

That the measurements from the slow clock transport synchronisation method are equivalent to the Einstein synchronisation and its isotropic speed of light can be interpreted to show that the one-way speed of light is indeed isotropic for a given set-up and not anisotropic. The problem with this is that anisotropy could not even be measured if it were to exist in this context. But this is definitely not a clear-cut zero sum game, there's no evidence suggesting anisotropy while there are observations that would at least suggest isotropy, but neither possibility can be ruled out. However, my initial point was that, could you have ultra-synchronised clocks, you could potentially be able to draw a reliable conclusion. But I'll dig into the publication the Wiki entry cites for the time dilation part in the slow clock section when I have the time.

[–] [email protected] 1 points 5 months ago (1 children)

And further down:

Unfortunately, if the one-way speed of light is anisotropic, the correct time dilation factor becomes {\displaystyle {\mathcal {T}}={\frac {1}{\gamma (1-\kappa v/c)}}}, with the anisotropy parameter κ between -1 and +1.[17] This introduces a new linear term, {\displaystyle \lim \_{\beta \to 0}{\mathcal {T}}=1+\kappa \beta +O(\beta ^{2})} (here {\displaystyle \beta =v/c}), meaning time dilation can no longer be ignored at small velocities, and slow clock-transport will fail to detect this anisotropy. Thus it is equivalent to Einstein synchronization.

[–] [email protected] 1 points 5 months ago

Yes, I understand that part, but it doesn't disprove that such an experiment could show isotropy. Instead, it says that it would always indicate isotropy, which is not entirely useful either, of course. I'll dig deeper into the publication behind that section when I have the time. Nonetheless, my original point still stands. With a highly synchronised clock, you could measure the (an)isotropy of the one-way speed of light. To determine whether the time dilation issue is surmountable I'll have to look at the actual research behind it.