Time and relativity (split from The Nature of Time)

[DanMP]

10 hours ago, Markus Hanke said:

Calculating the total time dilation when there is a combination of differences in gravitational potential, as well as relative motion, is a standard exercise that’s done in most undergrad courses on GR. It’s not that hard so long as you can use the Schwarzschild metric, which is highly symmetric. Usually it’s done in the context of GPS satellites, because ...

It may be highly symmetric for our GPS satellites, because they are in the same gravity well as the clock on the Earth's surface. I'm not sure that it would be the same and easy in my Moon-Earth scenario.

 

10 hours ago, Markus Hanke said:

We have had a large number of crafts of different kinds both on the surface of the moon, and in orbit around it. We have also bounced lasers and radar signals off the moon’s surface. All of these things explicitly take into account time dilation - it affects orbital mechanics, it affects light travel times, and it affects frequency shifts. No discrepancies with expected physics have ever been observed in that regard.

You are sure? Frequency shifts discrepancies due to Moons orbital velocity (relativistic Doppler effect) would be small. Detectable, yes (see Very-long-baseline interferometry), but did anyone bother to actually do it, I mean to search for discrepancies? I'm asking that because discrepancies/anomalies were found when they had 2 different ways of determining the velocity. Watch from 2:40

I'm not sure that this is the case, but when you make corrections in order to compensate for the relativistic effects (both in frequency shift and in time dilation) of the Earth movement through galaxy (they calculated the galaxy movement/speed), when in reality it should't be any kinematic effect due to gravity well movement, you may get such anomalies/discrepancies ...

 

10 hours ago, Markus Hanke said:

But it won’t ever be abandoned - that’s never going to happen, because it has already proven far too accurate and useful.

I wrote:

On 1/12/2023 at 5:31 PM, DanMP said:

GR would have to be adjusted or abandoned

The first option was adjusted.

 

10 hours ago, Markus Hanke said:

there is nothing whatsoever to suggest that anything out of the ordinary will happen if we perform that experiment of yours

Nothing whatsoever? A theory (my theory) published in Speculations is not nothing whatsoever. Not accepted here, yes, but not nothing whatsoever.

 

10 hours ago, Markus Hanke said:

Like I said, if you want to test time dilation on the moon’s surface with respect to an Earth observer, then bounce a laser or a radar echo off it, and compare propagation times and frequency shifts to what our models say they should be. It’s a much easier test that addresses the same issue of time dilation, and it’s been done many times since 1946 - Earth-Moon-Earth communications is in fact an entire sub-discipline of aeronautical engineering.

I searched the site you offered and found no reference to relativistic Doppler effects. Search for "shift" and see what you get. It is doable, yes, with Very-long-baseline interferometry, but it was really done?

 

10 hours ago, Markus Hanke said:

That’s true. But it’s also dangerous to become obsessed with a single tree, and forgetting the rest of the forest - which is what you seem to be doing here.

The keyword is here. Here I'm not allowed to speak freely, but, when I'll have the time, I will continue the discussion with you in the proper place (the Speculations sub-forum, in my old topic). The irony is that you (all) are in fact "forgetting the rest of the forest": the dark matter.

 

10 hours ago, Markus Hanke said:

On 1/12/2023 at 5:31 PM, DanMP said:

Loads of money? Tiny, compared to LHC, JWST, or gravitational-wave detectors.

It’s not the total amount that’s the problem, but the cost/benefit ratio.

You don't really know the benefits, just the cost, which is quite low with so many missions to the Moon. The cost of not doing it may be higher, because we are investing a lot in possibly wrong directions.

Edited January 13, 2023 by DanMP

[Bufofrog]

1 hour ago, DanMP said:

The cost of not doing it may be higher, because we are investing a lot in possibly wrong directions.

Nah, you're just obsessing about your idea.

[Ghideon]

Question @DanMP from a more naive/layman point of view: Assume we send a high precision clock as part of some planned mission. Also assume the clock measures time on the surface of the moon (or other celestial body) and there is a deviation compared to GR* predictions. Which one of A and B the likely cause?

A: GR is incorrect/incomplete in this scenario; new physics/modified GR is needed to explain.
B: The clock does not work as predicted. There are issues due to the environment (temperate, pressure, ...), the launch, transport or other engineering related issue.

If A actually happened, how do you rule out B? Or convince the scientific community that A is the cause? The scientific consensus as far as I can tell is that A is not possible in the proposed scientific setup. 

 

*) Or SR

[DanMP]

On 1/13/2023 at 11:19 PM, Ghideon said:

Question @DanMP ...

As for any anomaly/discrepancy, you must find and eliminate all the (possible) errors and/or redo the experiment, until you are sure that the "anomaly/discrepancy" is real.

As I wrote before, the test can be done first/also with a clock orbiting the Moon. Even from the Earth we may pre-test it, measuring spectral lines shift, but only if it's done with high accuracy.

I have also different kind of tests, easier to perform. About them I want to write first im my dedicated thread, but not very soon, because I am busy.

[Ghideon]

On 1/16/2023 at 2:59 PM, DanMP said:

As for any anomaly/discrepancy, you must find and eliminate all the (possible) errors and/or redo the experiment, until you are sure that the "anomaly/discrepancy" is real.

So how do you eliminate the errors?