SR and one-way light speed tests

Since the GPS measures distance with great precision can data be accessed to show how much the moon's gravity effects the orbits of the satelites? That should be a simple and constant perturbation (I guess) and it would be great to know the moon really does or does not move the satelites and therefore effects the signal.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>[Jim]: can data be accessed to show how much the moon's gravity effects the orbits of the satelites?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

Check the internet to see if anyone with receivers has posted GPS data. Usually, the data is so voluminous (gigabytes) that it has to be specially requested from organizations with high-precision receivers. You would need a DVD drive or multi-gigabyte ZIP drive to receive such data. Then it would be about six person-months of programming for a knowledgeable person to write all the code needed to analyze such data.

The data I have (as described in the article on our web site) is not publicly available because it was obtained during the period when GPS data was still classified. The Air Force (which still runs the GPS system) has no interest in making its regular monitoring data available except for approved scientific programs.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>That should be a simple and constant perturbation (I guess) and it would be great to know the moon really does or does not move the satelites and therefore effects the signal.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

You can either learn how to analyze data yourself (a multi-year effort), or take the word of those who have learned and have analyzed such data. I've done so, and the Moon's effects are just as calculated they should be. But what did you expect? The Moon's gravity has been used repeatedly now to boost the speeds of various spacecraft. If we couldn't calculate these things with at least eight decimals of true precision, our exploration of the solar system would not have been possible.

Decide whether you want to learn some celestial mechanics, then do it; or else pick the experts you trust. -|Tom|-

When the calculation is done what is the result-how many meters is the satelite moved by the moon? I'm not questioning the result or the quality of the calculation , I just want to know what it is in meters.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>[Jim]: When the calculation is done what is the result-how many meters is the satelite moved by the moon?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

I just did a botec ("back of the envelope calculation"), and got about 100 meters. -|Tom|-

OK,a 100 meters. The satelite is moved about a hundred meters nearer the moon when the satelite is nearest the moon. And so the satelite is a hundred meters higher above the Earth. So, is that an example of two masses(Earth and satelite) falling at a different rate because one mass (the satelite)is nearer the moon? Maybe this seems obscure but I'm puzzled by this force and may not ask the best questions.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>
[tvf]
A 1-way experiment cannot separate clock synchronization matters from speed changes, and is therefore impossible in principle unless we can use something faster than light to set the clocks.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
A rotating pipe ought to be a reasonable substitute for “something faster than light to set the clocks”. In fact, it provides the effect of an instantaneous signal between its ends.

Since no information is actually being transmitted, however, there are no SR style time-reversal/causality issues to contend with. And since the pipe and the clocks are all stationary wrt each other, there are no relative velocity issues to contend with.

Two remote clocks synchronized by such a pipe ought to be able to measure OWLS. Truely instantaneous signals (if such could exist) triggered by each detection of the alignment marks on each end of the pipe ought to reach a detector anywhere in the universe at the same instant.

(Dang. That was WAY too easy. What am I missing?)

LB

Some additional thoughts -

If the alignment mark extends the full length of the pipe then any number of clocks can be placed next to it and synchronized to the clocks at the ends.

Clocks that are moving (at any speed or speeds) parallel to the pipe could be synchronized with the stationary clocks at the ends or in between and with each other.

The rotating pipe is itself a clock ...