Proving speed of light constant “c” is the same in all directions?

[ESponge2000]

TL;DR

I believe The method of measurement of the speed of light involves the 2-way reading between reflecting mirrors

If I’m not mistaken, the synchronization of 2 clocks to conduct a measurement of the one-way speed of light is not possible since simultaneity is not possible and 2 clocks even if they are synchronized in a midpoint and slowly moved to opposite ends, depends on c being the same in all directions.

On the other hand we can observe the consequences of c in direction A <> c in direction B with a highly sharp telescope on a foreign object circling our planet, am I right ? Can we prove c to be within x% the same in all spatial directions?

 

[ESponge2000]

I also am wondering if there’s a way to get ever more precise in using 2 clocks to measure the speed of light in one direction by synchronizing those clocks and then not pulling them apart in linear opposite directions but rather by using some sort of spiral neutral method they assures that in process of each clock being moved they each spent an equal level of exposure to each angle hence preserving symmetric synch before conducting the experiment

 

[Vanadium 50]

The "one way speed of light" is not a measurable quantity. It depends entirely on how you synchronize clocks. Essentially, you have one equation in two unknowns. No amount of cleverness will let you solve that.

 

[Ibix]

No, it's not a question of precision. You can imagine a coordinate grid on spacetime just like you can on space. Choosing your one-way speed of light turns out to be choosing the "angle" between your time axis and one of your space axes. It makes no difference to anything physical, so it has no physical consequences, so it is not measurable. It just changes how you choose to interpret your measurements.

 

[cianfa72]

See also this recent thread.

 

[PeterDonis]

the synchronization of 2 clocks to conduct a measurement of the one-way speed of light is not possible since simultaneity is not possible

This is not correct. What is correct is that synchronizing 2 clocks/simutaneity requires adopting a convention. The most common such convention in SR is the Einstein synchronization convention. You can physically realize this convention; Einstein described how. But it's still a convention. There are other different synchronization conventions you could use and different procedures that would physically realize them. There is nothing in the laws of physics that picks out any one of those conventions as the "right" one. It's all a matter of human choice and convenience.

 

[ESponge2000]

Proof of the one-way speed of light = half the 2-way speed of light time , would this be proof ?

If the Voyager I space probe back when it had fully functional cameras (say around the time it took the photo of earth as a dot in a sunbeam at 40.5 AU away, or 6 light hours away), Enough that we could potentially blow up the earth image, confirm the sun-earth rotation position aligning to the time stamp on the voyager’s camera ,
We then have the voyager’s clock, its image of earth, the daytime display on planet earth, the awareness of what angle from the probe the image was taken , then if the probe took a photo in the opposite direction, and upon receiving the image, we also took a clear photo in the same direction as the probe, From these parameters would we not have some improved fine tuning of the speed of light in both directions, based on the alignments of earth and the image away from earth we can expect to align only with ones taken from an object we know its distance away is by means of its constant velocity, that it’s more likely c is the same both directions?

If c = same in both directions, then we can approximately expect
1) The time we received the probe’s image of earth, earth is circa 12 hours older than the image of earth captured in the photo

2) from the opposite longitude at the time we receive the image from the probe, the night sky above should be close to the same as when the probe shot the earth photo

 

[Ibix]

would this be proof ?

No. No such proof is possible.

 

[ESponge2000]

No. No such proof is possible.

Why? Assume we can adjust from what we know about earth’s rotation and orbit to identify the part of earth that most directly aligns with the direction the probe is receding from

 

[Ibix]

Why?

Because the one way speed of light depends on your choice of clock synchronisation. Any measure of the one way speed that you think doesn't depend on it has simply concealed your choice well enough that you failed to notice yourself making it.

 

[PeroK]

Why? Assume we can adjust from what we know about earth’s rotation and orbit to identify the part of earth that most directly aligns with the direction the probe is receding from

You ain't listening. Speed other than as measured locally is ambiguous and depends on your synchronization convention. Observational phenomena do not depend on a synchronization convention.

 

[PeterDonis]

You ain't listening.

Indeed. Enough is enough. The OP question has been sufficiently addressed. Thread closed.