B Time dilation in a planet-moon system

[Dale]

if there is a discrepancy between theory and reality, the clocks on the Moon would diverge from the clocks on the Earth more than expected

Why would the discrepancy between theory and reality be more noticeable with clocks on the moon than with different pairs of clocks on the earth? That makes no sense whatsoever.

One way to see that this makes no sense is to try to figure out which post-Newtonian parameter such an experiment would be sensitive to. Then you can look for the existing experiments that already constrain that parameter.

 

[PeterDonis]

if there is a discrepancy between theory and reality, the clocks on the Moon would diverge from the clocks on the Earth more than expected

If there were such a divergence we would already have seen it, in errors in the GPS system, for example. As has already been pointed out, the Moon's orbital speed is just not that fast, comparatively speaking.

 

[PeterDonis]

It is enough, as Hafele-Keating experiment proved.

Yes, which means that experiments we have already done are sufficient to test for any kind of divergence between theory and reality that the experiments you are proposing would test for. So the experiments you are proposing do not push the boundaries of our testing of theory against reality at all.

 

[Vanadium 50]

(as you can see from my threads/posts

Yes.

I would encourage you to drop this anti-relativity spin until you understand it better. I would also encourage you to work through a textbook (e.g. Taylor and Wheeler, 1st edition) as it will help your understanding more than a parade of increasingly complex scenarios. And, most importantly, I would encourage you to look at which experiments measure the same thing and how large the possible deviations from SR can be - otherwise it's just "yes, but has it ever been measured in Fresno on a Tuesday?"

You will discover that either test bodies are large and the effects are small or the other way around. That's just another way of saying we don't have starships.

 

[DanMP]

Why would the discrepancy between theory and reality be ...

What discrepancy? I wrote "if" bolded (if):

Probably, but even so, if there is a discrepancy between theory and reality, the clocks on the Moon would diverge from the clocks on the Earth more than expected. Over time this divergence would increase/accumulate and we would notice it, eventually.

and I wrote the above in order to point that even when the moon-based clock

rates will be adjusted from their "natural" rates just as Earth-based GPS satellite clock rates are--but adjusted to a different standard.

we still can use them to prove/disprove the theory.

I should have added that, as for the Earth-based GPS satellite clocks (with their adjusted rates), we still can use future adjusted Moon GPS clocks to proudly say that our theory of relativity was, yet again, confirmed.

It is better now?

 

[jbriggs444]

What discrepancy? I wrote "if" bolded (if):

You seem to be missing the point by a considerable margin.

If one is going to perform a test of relativity and has a test in mind, it would be efficient to spend some time thinking about what aspect of relativity that test measures. It would then be efficient to consider the possibility of other less expensive or more accurate tests.

we still can use them to prove/disprove the theory.

In terms of proving the theory, that ship has sailed. The theory is well accepted. The tick rate of clocks in the neighborhood of the moon is expected to follow the predictions of general relativity.

The information content of a confirming experiment would be essentially nil. The expected information content of an experiment (before knowing whether it is confirming or not) would also be essentially nil.

If you want to maximize the expected information yield of your experiments per unit cost, you want experiments where the outcomes are more like 50:50 rather than 1:bazillion.

 

[PeterDonis]

we still can use them to prove/disprove the theory.

Prove in the sense of providing yet more confirming data to add to the mountain of confirming data we already have, yes. But not in the sense of pushing the boundaries of the domain in which we've confirmed the theory; as I've already said, your proposed experiments do not do that at all.

Disprove? No. Not going to happen, because if any of the experiments you propose could produce data that conflicted with the theory, we would already have seen the same conflict in experiments we have already run. That's why I said your proposed experiments do not push the boundaries at all: because we already know what results your proposed experiments will have to give. In a "pushing the boundaries" experiment, we wouldn't, because we would be experimenting in a domain we had not experimentally probed before.

 

[Vanadium 50]

"None of our tests disprove SR"
"So hey - let;s run a less sensitive test!"

 

[jedishrfu]

It seems this is a good time to close this thread. The OP's question has been debated and now we are just rehashing our words.

Thank you all for contributing here.

Jedi