Relativity on Earth: Understanding Simultaneity & Time Dilation

[analyst5]

You are misunderstanding each other here. analyst5 is talking about 1-way speed and xox is talking about 2-way speed.

In a coordinate system where the 2-way speed is c, the 1-way speed could, with different sync conventions, take any value between ½c and ∞. If c₁ and c₂ are the 1-way speeds in opposite directions, they must be related by<br /> \frac{1}{c_1} + \frac{1}{c_2}= \frac{2}{c}<br />

So there's no way that the one way speed of light could go below 150000 km/s, no matter what synchonization parameter we use?

 

[xox]

So there's no way that the one way speed of light could go below 150000 km/s, no matter what synchonization parameter we use?

Actually, c_1,c_2 can take any value (if you use unphysical synchronization methods). Experiment tells us that c_1=c_2 if we use reasonable synchronization methods (either Einstein or slow clock transport). There is absolutely no reason to think that OWLS is anisotropic.

 

[Jorrie]

Actually, c_1,c_2 can take any value (if you use unphysical synchronization methods).

Only if you violate the isotropy of the two-way speed c, because as DrGreg said,

\frac{1}{c_1} + \frac{1}{c_2}= \frac{2}{c}

 

[xox]

Only if you violate the isotropy of the two-way speed c, because as DrGreg said,

\frac{1}{c_1} + \frac{1}{c_2}= \frac{2}{c}

Only if you violate the isotropy of ONE way light speed, not two-way light speed.
There is no experimental evidence supporting this concept, actually all experimental evidence supports the isotropy of OWLS.

 

[Nugatory]

Actually, c_1,c_2 can take any value (if you use unphysical synchronization methods).

Only if you violate the isotropy of the two-way speed c,

To the extent that two-way isotropy is experimentally confirmed (which is to say, pretty damned well), a synchronization method that leads to a violation of two-way isotropy is pretty much by definition unphysical, right? If so, you two are in violent agreement .

 

[xox]

To the extent that two-way isotropy is experimentally confirmed (which is to say, pretty damned well),

I am not aware of any experiments testing TWLS isotropy, all experiments I am aware of test OWLS isotropy, as I pointed out earlier in my response to DrGreg.

a synchronization method that leads to a violation of two-way isotropy is pretty much by definition unphysical, right?

Clock synchronization is tied to OWLS (actually, to the assumption that OWLS is isotropic, see Einstein synchronization), not to TWLS. It is true that OWLS isotropy results into TWLS isotropy. The reverse is not true, one can have TWLS isotropy without OWLS isotropy.

If so, you two are in violent agreement .

No, we are not in agreement. What Jorrie has posted doesn't even make sense (see above).

 

[xox]

I'll go a bit further, and note that using the usual TAI or GPS time synchronization conventions (which are different than the Einstein convention!), on the surface of the Earth the one-way east-west coordinate speed of light is not equal to the one-way west-east coordinate speed.

I'm sure Doctor Greg already knows this, I'm trying to clarify things for readers like analyst5.

With all respect I have to take exception to this statement. There are no global inertial frames of reference covering the whole circular trajectory of the GPS satellites. As such, there is no point in talking about the isotropy of coordinate light speed. Light speed is certainly isotropic LOCALLY, in a small interval along the trajectory. By contrast, over the WHOLE circle, the Sagnac effect MAKES IT LOOK AS IF the coordinate speeds in the opposing directions of circulation are different. This is a tremendous abuse of language, in reality we know is that what differs is the time taken by the em wavefronts to complete the circle. This effect, listed as the "Sagnac effect" in http://relativity.livingreviews.org/Articles/lrr-2003-1/fulltext.html is well known.

t_{\pm}=\frac{2 \pi R}{c \mp \omega R}

does not mean that the coordinate speed of the em wave has suddenly become anisotropic (c \mp \omega R). The mere notion of coordinate speed of light doesn't make sense in this case because of the absence of an inertial frame of reference covering the whole circle. Besides, one can argue that c \mp \omega R is technically the closing speed between the light front and the receiver, not the coordinate speed.

 

[Jorrie]

To the extent that two-way isotropy is experimentally confirmed (which is to say, pretty damned well), a synchronization method that leads to a violation of two-way isotropy is pretty much by definition unphysical, right? If so, you two are in violent agreement .

No, we are not in agreement. What Jorrie has posted doesn't even make sense (see above).

Then I think we are in non-violent disagreement...

Even ignoring the fact that the thread is about Earth's non-inertial frame and looking at a purely inertial frame, anisotropy of observed light propagation occurs when a non-standard synchrony is used. However, in any "sensible" non-standard synchrony, the observed two-way speed of light remains isotropic (because then synchronization of clocks does not play a role).

 

[DrGreg]

Experiment tells us that c_1=c_2 if we use reasonable synchronization methods (either Einstein or slow clock transport)

This seems to be the problem that you are failing to grasp. It's not experiment that tells us that, it's mathematical proof. If you use Einstein or slow clock transport it's mathematically guaranteed that c_1=c_2; no experiment required.

Experimental measurement of 1-way speed of light only makes sense if you are using some other sync method, and arguably the test is really whether the other method is equivalent to Einstein's or not.

 

[DrGreg]

So there's no way that the one way speed of light could go below 150000 km/s, no matter what synchonization parameter we use?

Provided the 2-way speed is c, and provided your sync method doesn't violate causality (i.e. doesn't allow signals to travel backwards in time), then yes.

It is possible to think up weird coordinate systems where those conditions might not be true, but not (if I understand correctly) in the context you were originally asking.

 

[xox]

This seems to be the problem that you are failing to grasp. It's not experiment that tells us that, it's mathematical proof. If you use Einstein or slow clock transport it's mathematically guaranteed that c_1=c_2; no experiment required.

This is not how the experimental tests of SR work, I explained that in my prior answer to you.

Experimental measurement of 1-way speed of light only makes sense if you are using some other sync method,

We do not have "some other sync method" available, we simply ASSUME one method of synchronization (by fixing the value of the parameter e) and we RUN the experiment. We use the observed anisotropy in order to constrict the parameters (3 in the case of M-S and 17 for SME). For example, e=-1 for Einstein sync. I already explained that to you in my earlier post to you.

and arguably the test is really whether the other method is equivalent to Einstein's or not.

This is definitely not what the tests measure, I will have to refer you again to my corrections to your claims. If you read through the papers dedicated to constraining light speed anisotropy you find that there are no clocks involved, there is just an assumption about the value ascribed to parameter e. The reason for that is the fact that the assumption on clock synchronization results into the formula for "anisotropic" OWLS. It is THIS particular formula that is used in developing the theory of the experiment.

 

[Dale]

We do not have "some other sync method" available, we simply ASSUME one method of synchronization

Yes, we do. We can make different assumptions. This is well-known in the literature.

 

[xox]

Yes, we do. We can make different assumptions. This is well-known in the literature.

To my best knowledge, the Mansouri-Sexl test theory provides for the only two sync methods I listed (Einstein and slow clock transport). SME does not employ ANY form of clock synchronization. I would very much like to learn about the other methods that you are referring to, could you list some references?

 

[Dale]

Mansouri-Sexl test theory allows for a wide range of alternative sync methods by varying e.

Yes, I can provide references, but it will have to wait a day or two, apologies.

 

[xox]

Mansouri-Sexl test theory allows for a wide range of alternative sync methods by varying e.

That is true. Nevertheless, the only two methods that I have encountered in both the original (theoretical) papers and in the experimental applications are Einstein and slow clock transport, no experiment uses another e since Clifford Will's proof that the dependency on e cannot be exposed by experiment. Granted, my knowledge is not exhaustive, I haven't read all the papers on the subject, I am always interested in learning new things.

Yes, I can provide references, but it will have to wait a day or two, apologies.

Thank you, I appreciate that, I will await with great interest.

 

[pervect]

With all respect I have to take exception to this statement. There are no global inertial frames of reference covering the whole circular trajectory of the GPS satellites.

I agree, and more to the point there isn't a global inertial frame of reference covering the surface of the Earth (more precisely, the geoid), due to the inability to perform a global Einstein clock synchronization over the geoid,

As such, there is no point in talking about the isotropy of coordinate light speed. Light speed is certainly isotropic LOCALLY, in a small interval along the trajectory. By contrast, over the WHOLE circle, the Sagnac effect MAKES IT LOOK AS IF the coordinate speeds in the opposing directions of circulation are different.

I regard coordinate speeds in general as having little physical significance. Some people get hung up on coordinate speeds by ascribing significance to them they don't have. My view is that in GR, coordinates are perfectly general, as are the coordinate velocities, and that it is an unfortunate error when people expect them to have any particular physical properties that are not derived from the way the coordinates are chosen.

I would disagree in detail with your remarks above, though I don't think our outlooks are actually all that different. I would say that because the TAI coordinate system doesn't use an isotropic clock sychronization scheme (and can't, because any isotropic synchronization scheme won't be global), coordinate speeds are in fact different in different directions, not just "appearing" to be different.

I would agree that using a local clock isotropic synchronization scheme (combined with a suitable local definition of distance), the one way speed of light is constant everywhere and that this is an important principle of relativity. This in no way conflicts with my other point, though it is a good idea to occasioanlly remind readers of it.

I would also agree that the "Sagnac effect" is a good keyword to do more reading on the topic, with the provision that one still needs to use the usual care in evaluating the quality of resources if one is reading on the internet, there are a lot of fringe writings on the topic, some of which use the same language (Sagnac effect, in particular) as the non-fringe writings.

This is a tremendous abuse of language, in reality we know is that what differs is the time taken by the em wavefronts to complete the circle. This effect, listed as the "Sagnac effect" in http://relativity.livingreviews.org/Articles/lrr-2003-1/fulltext.html is well known.

t_{\pm}=\frac{2 \pi R}{c \mp \omega R}

does not mean that the coordinate speed of the em wave has suddenly become anisotropic (c \mp \omega R). The mere notion of coordinate speed of light doesn't make sense in this case because of the absence of an inertial frame of reference covering the whole circle. Besides, one can argue that c \mp \omega R is technically the closing speed between the light front and the receiver, not the coordinate speed.

I don't see why you say this, though I have no argument with your Living Reviews reference (which is a good source, though perhaps to technical for some readers).

Perhaps we disagree on the definition of the coordinate speed of light. I should first specify precisely the coordinates I'm using. These are the time and distance coordinates of the rotating polar form of the ECEF coordinate system, with the time scale set so that clocks on the geoid keep coordinate time, defined by the metric in [22] of http://relativity.livingreviews.org/open?pubNo=lrr-2003-1&amp;page=articlese3.html and accurate to order (1/c^2)

See http://arxiv.org/abs/gr-qc/9508043 for how defining a metric also defines the coordinates (when combined with a suitable set of reference objects).

Equation (1) defines not only the gravitational field that is assumed, but also the coordinate system in which it is presented. There is no other source of information about the coordinates apart from the expression for the metric. It is also not possible to define the coordinate system
unambiguously in any way that does not require a unique expression for the metric. In most cases where the coordinates are chosen for computational convenience, the expression for the metric is the most efficient way to communicate clearly the choice of coordinates that is being made.

Then, given the coordinate choice, as defined by the metric, it's a simple matter of fact to note that when you solve for the null geodesics, and calculate the value of $d\phi' / dt''$ for east-west and west-east geodesics as the equator, you get different values for this quantity, which is the coordinate velocity.

Mathematically, we can point the finger at the term responsible for the so-called "Sagnac effect":

$2 \omega_E r'^2 sin^2 \theta' d\phi' dt''$

The coordinate velocity IS different in both directions, it's not an "appearance". This can be explained by the fact that in general, pairs of clocks rotating along with the Earth (which at rest in this coordinate system), are not Einstein synchronized, and thus we don't EXPECT coordinate speeds to be isotropic, because the coordinate system itself isn't isotropic.

 

[xox]

I agree, and more to the point there isn't a global inertial frame of reference covering the surface of the Earth (more precisely, the geoid), due to the inability to perform a global Einstein clock synchronization over the geoid,
I regard coordinate speeds in general as having little physical significance. Some people get hung up on coordinate speeds by ascribing significance to them they don't have. My view is that in GR, coordinates are perfectly general, as are the coordinate velocities, and that it is an unfortunate error when people expect them to have any particular physical properties that are not derived from the way the coordinates are chosen.

I would disagree in detail with your remarks above, though I don't think our outlooks are actually all that different. I would say that because the TAI coordinate system doesn't use an isotropic clock sychronization scheme (and can't, because any isotropic synchronization scheme won't be global), coordinate speeds are in fact different in different directions, not just "appearing" to be different.

I would agree that using a local clock isotropic synchronization scheme (combined with a suitable local definition of distance), the one way speed of light is constant everywhere and that this is an important principle of relativity. This in no way conflicts with my other point, though it is a good idea to occasioanlly remind readers of it.

I would also agree that the "Sagnac effect" is a good keyword to do more reading on the topic, with the provision that one still needs to use the usual care in evaluating the quality of resources if one is reading on the internet, there are a lot of fringe writings on the topic, some of which use the same language (Sagnac effect, in particular) as the non-fringe writings.
I don't see why you say this, though I have no argument with your Living Reviews reference (which is a good source, though perhaps to technical for some readers).

Perhaps we disagree on the definition of the coordinate speed of light. I should first specify precisely the coordinates I'm using. These are the time and distance coordinates of the rotating polar form of the ECEF coordinate system, with the time scale set so that clocks on the geoid keep coordinate time, defined by the metric in [22] of http://relativity.livingreviews.org/open?pubNo=lrr-2003-1&amp;page=articlese3.html and accurate to order (1/c^2)

See http://arxiv.org/abs/gr-qc/9508043 for how defining a metric also defines the coordinates (when combined with a suitable set of reference objects).
Then, given the coordinate choice, as defined by the metric, it's a simple matter of fact to note that when you solve for the null geodesics, and calculate the value of $d\phi' / dt''$ for east-west and west-east geodesics as the equator, you get different values for this quantity, which is the coordinate velocity.

Mathematically, we can point the finger at the term responsible for the so-called "Sagnac effect":

$2 \omega_E r'^2 sin^2 \theta' d\phi' dt''$

The coordinate velocity IS different in both directions, it's not an "appearance". This can be explained by the fact that in general, pairs of clocks rotating along with the Earth (which at rest in this coordinate system), are not Einstein synchronized, and thus we don't EXPECT coordinate speeds to be isotropic, because the coordinate system itself isn't isotropic.

I enjoy very much interacting with you, you are not only very knowledgeable but also very pleasant. Looks like we agree on all the main points, I am sorry for being somewhat harsh in my tone referring to the Sagnac effect. I can explain why I consider the speed to be "closing speed" and not "coordinate speed" but I think that it is a very unimportant point , so I'll pass.
As a point of interest, I would only mention that my approach for calculating the "Sagnac effect" in GPS is to start with the Kerr solution and to make \theta=\frac{\pi}{2}, dr=0 (circular trajectory at the Equator). This results into the equation degree 2:

(r^2+\alpha^2+\frac{r_s r \alpha^2}{\rho^2})(\frac{d \phi}{dt})^2-2\frac{r_s r \alpha^2}{\rho^2}\frac{d \phi}{dt}-(1-\frac{r_s r}{\rho^2})c^2=0

with two distinct solutions corresponding to the two distinct "coordinate speeds" of light.

 

[analyst5]

Provided the 2-way speed is c, and provided your sync method doesn't violate causality (i.e. doesn't allow signals to travel backwards in time), then yes.

It is possible to think up weird coordinate systems where those conditions might not be true, but not (if I understand correctly) in the context you were originally asking.

The same applies to non-inertial frames? In one document I red that setting the synchonization parameter to a value different from 1/2 is equivalent to defining simultaneity for a non-inertial frame.

 

[WannabeNewton]

The same applies to non-inertial frames?

That the two-way speed of light is always $c$? No. Not unless one does the radar echo experiment locally. If the radar echo experiment is performed globally then all kinds of weird things can happen with the two-way speed of light. Just take for example the frame of a uniformly accelerating observer in flat space-time.

 

[xox]

In one document I red that setting the synchonization parameter to a value different from 1/2 is equivalent to defining simultaneity for a non-inertial frame.

This cannot be correct since e=1 defines Einstein synchronization. Where did you read such a thing?

 

[WannabeNewton]

This cannot be correct since e=1 defines Einstein synchronization. Where did you read such a thing?

First of all $\epsilon = \frac{1}{2}$ is Einstein synchronization in Grunbaum's framework of synchronization in inertial frames so analyst is perfectly correct. Secondly it is a well known fact that if $\epsilon \in (0,1) - \{1/2 \}$ in an inertial frame then such a synchronization is equivalent to a choice of synchronization for a non-inertial frame. See: http://www.mcps.umn.edu/assets/pdf/8.13_friedman.pdf

 

[xox]

First of all $\epsilon = \frac{1}{2}$ is Einstein synchronization in Grunbaum's framework of synchronization in inertial frames so analyst is perfectly correct.

According to the first paper of the Mansouri-Sexl series, page 501, it is \epsilon=\pm 1 that corresponds to Einstein synchronization . For obvious reasons, since one recovers the Lorentz transform from the generalized M-S transform.

Secondly it is a well known fact that if $\epsilon \in (0,1) - \{1/2 \}$ in an inertial frame then such a synchronization is equivalent to a choice of synchronization for a non-inertial frame. See: http://www.mcps.umn.edu/assets/pdf/8.13_friedman.pdf

Thank you, I read this, we are talking about different meanings of \epsilon.

 

[WannabeNewton]

Thank you, I read this, we are talking about different meanings of \epsilon.

Yes the Mansouri-Sexl formulation and the Grunbaum formulation are different frameworks of synchronization for inertial frames. Sorry for the misunderstanding. I'm almost entirely sure analyst was referring to the Grunbaum formulation.

As an aside, which paper are you referring to? Do you happen to have a link? Thanks in advance.

 

[xox]

Yes the Mansouri-Sexl formulation and the Grunbaum formulation are different frameworks of synchronization for inertial frames. Sorry for the misunderstanding. I'm almost entirely sure analyst was referring to the Grunbaum formulation.

As an aside, which paper are you referring to? Do you happen to have a link? Thanks in advance.

This one (there are two more in the series).

 

[analyst5]

That the two-way speed of light is always $c$? No. Not unless one does the radar echo experiment locally. If the radar echo experiment is performed globally then all kinds of weird things can happen with the two-way speed of light. Just take for example the frame of a uniformly accelerating observer in flat space-time.

Can you perhaps give more detail on this, I'm really interested?

 

[WannabeNewton]

Can you perhaps give more detail on this, I'm really interested?

https://www.physicsforums.com/showthread.php?t=730009

 

[Dale]

To my best knowledge, the Mansouri-Sexl test theory provides for the only two sync methods I listed (Einstein and slow clock transport). SME does not employ ANY form of clock synchronization. I would very much like to learn about the other methods that you are referring to, could you list some references?

Hi xox, sorry about the delay. I was swamped with final training and preparation for my black belt test!

Here is a famous pair of papers on synchronization by Winnie: http://www.jstor.org/discover/10.2307/186029?uid=3739776&uid=2&uid=4&uid=3739256&sid=21104181923193
http://www.jstor.org/discover/10.2307/186671?uid=3739776&uid=2&uid=4&uid=3739256&sid=21104181923193

Here is one by Anderson:
http://www.sciencedirect.com/science/article/pii/S0370157397000513

This one by Debs is about synchronization and the twin paradox:
http://scitation.aip.org/content/aapt/journal/ajp/64/4/10.1119/1.18252

I am sure that there are more, but those are the ones that have come up here in other threads that I have participated in (and learned a lot in). And of course, you are aware of the Mansouri Sexl test theory, so you can plug in different values for the synchronization parameter in that and see what happens.

 

[xox]

Hi xox, sorry about the delay. I was swamped with final training and preparation for my black belt test!

Here is a famous pair of papers on synchronization by Winnie: http://www.jstor.org/discover/10.2307/186029?uid=3739776&uid=2&uid=4&uid=3739256&sid=21104181923193
http://www.jstor.org/discover/10.2307/186671?uid=3739776&uid=2&uid=4&uid=3739256&sid=21104181923193

Unfortunately both are behind the paying wall. From the abstracts, I see no relevance, would you happen to have a copy of the papers that you could share?

Here is one by Anderson:
http://www.sciencedirect.com/science/article/pii/S0370157397000513

This one seems truly relevant and quite interesting. If I were to get a copy, this is the one that I would prefer to get such that we could discuss it. Note that they are not talking about M-S, they are creating their own theory.

This one by Debs is about synchronization and the twin paradox:
http://scitation.aip.org/content/aapt/journal/ajp/64/4/10.1119/1.18252

Don't see any relevance in this one either. I would love to debate the Anderson-Stedman paper, do you have a copy that we could share?

I am sure that there are more, but those are the ones that have come up here in other threads that I have participated in (and learned a lot in). And of course, you are aware of the Mansouri Sexl test theory, so you can plug in different values for the synchronization parameter in that and see what happens.

The only TWO values that I have seen, in ALL the experimental papers that I have read (and I read a LOT of them) are the values (more correctly, functions of v) corresponding for Einstein synch and for slow clock transport synch. I understand that you can plug in all kinds of functions of v but I never saw anything different from the two that I just cited. Note that the papers you cited are all theoretical, none of them is experimental.

SME , being based on an extension to the Lagrangian, does not employ ANY form of clock synchronization, either in the photon sector or in the matter sector. Actually, there are NO clocks to be synchronized in ANY of the papers describing the tests. Since SME is taking over from M-S as a foundation for a test theory, the idea of yet another, to be defined, clock synchronization becomes a moot point.

 

[Dale]

Sorry, I don't have non-paywall access, and it is against forum policy to violate copyright, so I cannot just post a copy. I understand the reluctance to purchase.

The only TWO values that I have seen, in ALL the experimental papers that I have read (and I read a LOT of them) are the values (more correctly, functions of v) corresponding for Einstein synch and for slow clock transport synch. I understand that you can plug in all kinds of functions of v but I never saw anything different from the two that I just cited.

The point is that, as you admit, you CAN plug in anything you want. It is a free parameter which is unconstrained by experiment. That people consistently prefer the typical values doesn't change that fact.

Note that the papers you cited are all theoretical, none of them is experimental.

Obviously. Synchronization, as has been mentioned previously, cannot be determined by experiment.

 

[xox]

Sorry, I don't have non-paywall access, and it is against forum policy to violate copyright, so I cannot just post a copy. I understand the reluctance to purchase.The point is that, as you admit, you CAN plug in anything you want. It is a free parameter which is unconstrained by experiment. That people consistently prefer the typical values doesn't change that fact.

My point was a much stronger one: no experimental paper shows any other synchronization than the two I mentioned. None of the three papers that you cited disproves that, actually, the three papers are quite orthogonal to the debate we were having on the subject.

Obviously. Synchronization, as has been mentioned previously, cannot be determined by experiment.

I'm afraid that you missed the point, the papers you cited do not support your earlier claim. Actually, they are totally orthogonal to the claim.

 

[Dale]

My claim was only that we can make different assumptions for our synchronization convention. Clearly we can. All of these papers describe different assumptions that we can make, and the test theory parameter is a completely free parameter.

I am not sure what other claim you think I was discussing. I certainly never made any claims about which synchronization conventions have actually been used by experimental physicists.

 

[xox]

Mansouri-Sexl test theory allows for a wide range of alternative sync methods by varying e.

Yes, I can provide references, but it will have to wait a day or two, apologies.

True, nevertheless, the only two methods that I have encountered in both the original (theoretical) papers and in the experimental applications are Einstein and slow clock transport, no experiment uses another e since Clifford Will's proof that the dependency on e cannot be exposed by experiment. Neither of your three references shows any of use of "alternative synch" in a real life experiment.
Actually, two of the references have nothing to do with the Mansouri theory, the third one is a proper extension to non-inertial frames (rotating).

I certainly never made any claims about which synchronization conventions have actually been used by experimental physicists

True, it is I who did that in my answer to your post. The point is that any "other" synchronization was never used by experimenters.

 

[Dale]

True, nevertheless, the only two methods that I have encountered in both the original (theoretical) papers and in the experimental applications are Einstein and slow clock transport, ... The point is that any "other" synchronization was never used by experimenters.

I never disputed that.

no experiment uses another e since Clifford Will's proof that the dependency on e cannot be exposed by experiment.

That is essentially my point. It cannot be exposed by experiment, it is a matter of convention and we could adopt a different convention.

Actually, two of the references have nothing to do with the Mansouri theory

So what? I claimed that they were different possible assumptions. I did not claim any relationship with other possible assumptions.

You are strangely difficult to communicate with. You seem to think that I am making different claims than what I think I am making, and some of your arguments seem to be actively supporting my position but you state them as though you think that they are contradictory to it. It feels like having a conversation with a particularly smart slot machine.

 

[xox]

So what? I claimed that they were different possible assumptions. I did not claim any relationship with other possible assumptions.

We were discussing the Mansouri-Sexl theory. You provided references that have nothing to do with the M-S theory, despite your promise to provide references supporting your PoV.

You are strangely difficult to communicate with. You seem to think that I am making different claims than what I think I am making, and some of your arguments seem to be actively supporting my position but you state them as though you think that they are contradictory to it. It feels like having a conversation with a particularly smart slot machine.

The fact that you fail to grasp the differences doesn't entitle you to become abusive.

 

[Dale]

The fact that you fail to grasp the differences doesn't entitle you to become abusive.

I do apologize. You are right, that was out of line to compare you to a slot machine. Unfortunately, I was tired and I wrote it and went to bed without re-reading it and toning it down. My sincere apologies.

We were discussing the Mansouri-Sexl theory. You provided references that have nothing to do with the M-S theory, despite your promise to provide references supporting your PoV.

Here is an example of the difficulty in communication that is frustrating me. I claimed (and showed) that we can make different assumptions. The M-S free parameter is a single example, not the sole example, nor did I ever claim that it was the only example. Why should my response be limited to M-S when there are other examples? This is why communication with you feels random. I make a point, provide an example, provide references, and you respond complaining that the references don't make a different point and incidentally mentioning a proof of my point.

Again, my point is only the following: contrary to your statements in post 61 it is well-known in the literature that we do have other synch methods available and we can make assumptions that differ from the standard ones.

That point I have demonstrated. My comments about M-S are only an attempt to build from common ground. Since you are aware of M-S you should have been aware that the synchronization parameter is an example of other synch methods and that the standard one is only a special case. Particularly since you are aware of Clifford Will's proof that experiments cannot fix the synchronization parameter.

 

[xox]

I do apologize. You are right, that was out of line to compare you to a slot machine. Unfortunately, I was tired and I wrote it and went to bed without re-reading it and toning it down. My sincere apologies.

Accepted.

Here is an example of the difficulty in communication that is frustrating me. I claimed (and showed) that we can make different assumptions. The M-S free parameter is a single example, not the sole example, nor did I ever claim that it was the only example. Why should my response be limited to M-S when there are other examples?

Because we were discussing precisely the M-S theory. Because I made it clear that in the M-S theory the only two synchs that I have encountered are Einstein and slow transport, so I was expecting counter-examples to my exact statement as per your answer, this is not what you have provided, so I reacted by pointing this out.

This is why communication with you feels random. I make a point, provide an example, provide references, and you respond complaining that the references don't make a different point and incidentally mentioning a proof of my point.

Actually, it is exactly the other way around. See above.

Again, my point is only the following: contrary to your statements in post 61 it is well-known in the literature that we do have other synch methods available and we can make assumptions that differ from the standard ones.

The exact statement was that I have not encountered any other synchs in the experimental papers based on the M-S theory.

That point I have demonstrated. My comments about M-S are only an attempt to build from common ground.

Well, now you understand why we do not communicate well, I tend to be very precise.

Since you are aware of M-S you should have been aware that the synchronization parameter is an example of other synch methods and that the standard one is only a special case. Particularly since you are aware of Clifford Will's proof that experiments cannot fix the synchronization parameter.

All true. So, are we clear now?

 

[Dale]

All true. So, are we clear now?

Yes? I think.

 

[xox]

Yes? I think.

Good :-)

 

[analyst5]

@Dale, I've red the links you provided, but it added even more confusion to my level of understanding. First thing, I didn't know that velocities change when the one-way speed of light changes. Ok, I understand that it isn't a neccessity that the speed of light is isotropical, and that its limit in an arbitary direction is between c/2 and infinity. I understand that, of course from a perspective of an inertial frame. But what about non-inertial frames, does the same thing apply here? I know that it's a matter of convention, but there should exist some rules for defining the limits like there are in non-standard method of synchronization in inertial frames. Can we consider the speed of light to be 300000 km/s and isotropic in an arbitary convention from our Earth frame, for instance?

 

[analyst5]

And regarding lengths and time dilations viewed from a moving frame, when using a different convention it's possible that the rods increase in coordinate length instead of contracting, and the same applies to time dilation, right?