# Clock synchronization process

1. May 18, 2014

### analyst5

This is basically a follow-up to some questions from a previous thread regarding Einstein synchronization and other methods. I don't understand the alternative methods when the synchronization parameter isn't 1/2 and its connection to the speed of light. Basically it means that the light is quicker in one direction than the other, but there are is an infinite number of directions, so I don't understand which light rays are quicker than the others. For instance, let's suppose that we sync two distant clocks with a non-standard method. So the light from the front, in one case, may be faster than the light coming from the back, right? How would the light mentioned in this case behave in other directions regarding its velocity?

2. May 18, 2014

### xox

If light "were quicker in one direction than in the other", then there would be no operational way of synchronizing clocks by using light signals. Fortunately, experiment shows that light speed (one way) is isotropic. Even if it weren't, you could still synchronize clocks (via slow clock transport, as they did it for the ill-fated "neutrino faster than light" experiment), you just couldn't use light signals.

3. May 18, 2014

### analyst5

Is it also isotropical in non-inertial frames, but can have a different value than c?

4. May 18, 2014

### WannabeNewton

Yes there is. One simply uses Grunbaum's $\epsilon$-synchrony for inertial frames.

No it doesn't. There is no experiment that can show the one-way speed of light is isotropic in inertial frames. The isotropy of the one-way speed of light in inertial frames is purely a convention.

5. May 18, 2014

### xox

There is a very large spectrum of tests on OWLS anisotropy, here is a very small sample. I can provide you with many more tests of OWLS anisotropy.

6. May 18, 2014

### xox

While the predictions derived from such departures from Einstein synchronization produce theories experimentally indistinguishable from SR, the defined clock time varies from Einstein's according to the distance in a specific direction.(see Zhang's book). So, in earnest, the clocks aren't synchronized anymore because they show different times.To make matters worse, the difference varies with distance.

Last edited: May 19, 2014
7. May 19, 2014

### analyst5

Ok, so if we specify the light speed in one direction and automatically the speed in the opposite direction, how do speeds of light in other directions follow from that?

8. May 19, 2014

### WannabeNewton

Elementary treatments tend to stick to 1-dimensional expositions however the same thing you do for 1-dimension applies to 3-dimensions except now you have to treat 3 independent directions as opposed to just 1.

9. May 19, 2014

### WannabeNewton

That doesn't mean they aren't synchronized as the choice of $\epsilon$ is what defines the synchronization of clocks. The clocks may show different times according to the Einstein synchronization convention but not according to my other choice of $\epsilon$. None of your objects have anything to do with whether or not one-way anisotropic speed of light synchronizations are available (and they clearly are).

Did you read the opening paragraph of the relevant subsection in that link?

10. May 19, 2014

### xox

Yes, I am very familiar with the opening paragraph, I know Tom Roberts personally and I pointed out to him, repeatedly, that the way he wrote it it conveys the wrong message. But he is stubborn and he would not change it.
Your objection does not change the fact that there is a large spectrum of OWLS anisotropy tests. Most (if not all) experimentalists would disagree with your statement:

The test theories that Tom Roberts is talking about are exactly the instruments used to constrain light speed anisotropy. This is a much better way of explaining things than the negative way Tom Roberts wrote it.

11. May 19, 2014

### analyst5

I understand the basic premise of your post, but could you please give some additional details when comparing 1-dimensional analysis as opposed to 3-dimensional sync situation?