Age of Universe relative to what?

[my_wan]

I take it you don't agree with Einstein's position in his 1905 paper introducing SR?

WOW! After all that explaining why the SR version is superior!

 

[ghwellsjr]

I take it you don't agree with Einstein's position in his 1905 paper introducing SR?

WOW! After all that explaining why the SR version is superior!

Do you agree with this statement:

If at the point A of space there is a clock, an observer at A can determine the time values of events in the immediate proximity of A by finding the positions of the hands which are simultaneous with these events. If there is at the point B of space another clock in all respects resembling the one at A, it is possible for an observer at B to determine the time values of events in the immediate neighbourhood of B. But it is not possible without further assumption to compare, in respect of time, an event at A with an event at B. We have so far defined only an “A time” and a “B time.” We have not defined a common “time” for A and B, for the latter cannot be defined at all unless we establish by definition that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A.

 

[my_wan]

Do you agree with this statement:

If at the point A of space there is a clock, an observer at A can determine the time values of events in the immediate proximity of A by finding the positions of the hands which are simultaneous with these events. If there is at the point B of space another clock in all respects resembling the one at A, it is possible for an observer at B to determine the time values of events in the immediate neighbourhood of B. But it is not possible without further assumption to compare, in respect of time, an event at A with an event at B. We have so far defined only an “A time” and a “B time.” We have not defined a common “time” for A and B, for the latter cannot be defined at all unless we establish by definition that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A.

Of course I agree. Also note what I marked in red. This indicates that we are of course naturally talking about a definition, not a uniquely valid definition but simply a valid definition. Just like coordinate choices are non-unique but valid definition of metrics, as is which meteor the kinetic energy is located at.

 

[ghwellsjr]

Well, then, I'm wondering why you made this statement:

It is also possible to measure the one way speed of light...

 

[Dale]

That's what makes LET physically defensible.

I don't think that LET is on-topic for this thread. However, I am in agreement with the remainder of your response.

 

[Dale]

Because it has been said that measuring a one way speed of light was impossible as a result of the need to synchronize a pair of clocks. This is wrong, and I've learned that others have already demonstrated that here.

Here is where you and I disagree. The definition of the synchronization convention and the definition of the one-way speed of light are the same thing.

Suppose you have a flash bulb and a ring of detectors at some fixed distance d away from them. The flash bulb goes off at t=0 and the detectors each detect a flash. When does each detector detect the flash? If they all detect them at the same time, t=d/c, then the one way speed of light is c and they detect them simultaneously. If they detect at different times, then they are not simultaneous and the speed of light is not c for each path. The one way speed of light any your synchronization process are the same thing.

Your claims to the contrary are incorrect.

 

[my_wan]

However,[/PLAIN] Will [7] showed that experiments which test the isotropy in one-way or two-way (round-trip) experiments have observables that depend on test functions but not on the synchronization procedure. He noted that “the synchronization of clocks played no role in the interpretation of experiments provided that one is careful to express the results in terms of physically measurable quantities.” Hence the synchronization is irrelevant for our one-way speed of light test since we express our results in terms of physically measurable quantities.

That's why I said it. Already said that to.

 

[my_wan]

Here is where you and I disagree. The definition of the synchronization convention and the definition of the one-way speed of light are the same thing.

Suppose you have a flash bulb and a ring of detectors at some fixed distance d away from them. The flash bulb goes off at t=0 and the detectors each detect a flash. When does each detector detect the flash? If they all detect them at the same time, t=d/c, then the one way speed of light is c and they detect them simultaneously. If they detect at different times, then they are not simultaneous and the speed of light is not c for each path. The one way speed of light any your synchronization process are the same thing.

Your claims to the contrary are incorrect.

I don't have a flash period, I have a light on 100% of the time. Neither do I have a t=0 anywhere period, or t= anything. Nor is there any pair of events that I measure for comparison. The pure geometry does all that for me, and if you want to make a case about it then respond to what I already responded to. Instead of this t= strawman when clearly i do not label t= to say what RPM something is rotating. I don't care when its rotating nor when the light was on.

 

[ghwellsjr]

Originally Posted by http://arxiv.org/abs/1103.6086
However, Will [7] showed that experiments which test the isotropy in one-way or two-way (round-trip) experiments have observables that depend on test functions but not on the synchronization procedure. He noted that “the synchronization of clocks played no role in the interpretation of experiments provided that one is careful to express the results in terms of physically measurable quantities.” Hence the synchronization is irrelevant for our one-way speed of light test since we express our results in terms of physically measurable quantities..

That's why I said it. Already said that to.

OK, now I understand what's going on. That paper, which you said, "is sufficiently close to what I proposed to qualify the general idea" is not talking about measuring the value of the one-way speed of light or measuring the propagation time of the light traveling in one direction. Rather it is measuring the constancy of the speed of light which does not require synchronized clocks.

The wikipedia article on "The one-way speed of light" that I encouraged you to read back in post #60 makes this clear. If you look at the section entitled "Experiments that can be done on the one-way speed of light" you will see that "it is possible to carry out experiments that measure a change in the one-way speed of light". As the article points out, "In such experiments the clocks may be synchronized in any convenient way, since it is only a change of speed that is being measured." In other words, it doesn't matter if the clocks are synchronized at all or even if actual clocks are used which is the case in the paper and in your proposed experiment.

But these experiments cannot and do not claim to measure the value of the speed of light which is what we mean by the statement that the one-way speed of light cannot be measured.

The experiment in the paper (and I presume your proposed experiment) is measuring how the speed of light changes during a period of 24 hours as the Earth points the apparatus in different directions and they did measure a sinusoidal pattern. They pointed their apparatus along a North-South direction to minimize the difference. If they were to repeat their experiment on the equator instead of at Toronto, this sinusoidal pattern may be eliminated and if they were to point their apparatus along an East-West direction, they would maximize the amplitude of the sinusoidal pattern, I believe.

Have you thought about why there should be a sinusoidal pattern with a period of approximately 24 hours? Are they measuring an actual change in the one-way speed of light as the apparatus is pointed in different directions? Are they now finally measuring an ether wind?

 

[my_wan]

The wikipedia article on "The one-way speed of light" that I encouraged you to read back in post #60 makes this clear.

The[/PLAIN] "one-way" speed of light from a source to a detector, cannot be measured independently of a convention as to how to synchronize the clocks at the source and the detector.

and:

Although[/PLAIN] experiments cannot be done in which the one-way speed of light is measured independently of any clock synchronization scheme,[...]

And I'm telling that is wrong, as the sources I quoted and will quote again states, again repeating myself over and over on this point only to be ignored and told I said something else. Yet here you are pretending I must not have even read it! Was it me not reading when I bent over backwards explaining the superiority of SR and have you response say I must not agree with SR?

Get this straight:
1) The ONLY timing device is the RPM of the pipe, period.
2) The ONLY variable this relates to is a distance, not time.
(Hence when wiki says "synchronize clocks" it is dead wrong.)
3) The ONLY assumptions being made is Newtonian, in spite of knowing that is going to be wrong.
Only by insisting that my tape measure is a clock can you claim I am synchronizing a pair of clocks. Hence this is a one way speed measurement in precisely the same way Michelson Morley was a two way speed test.

Note the red letters:

Will[/PLAIN] [7] showed that experiments which test the isotropy in one-way or two-way (round-trip) experiments have observables that depend on test functions but not on the synchronization procedure. He noted that “the synchronization of clocks played no role in the interpretation of experiments provided that one is careful to express the results in terms of physically measurable quantities.” Hence the synchronization is irrelevant for our one-way speed of light test since we express our results in terms of physically measurable quantities

Also in the other paper:

However,[/PLAIN] Will [49] showed that experiments which test the isotropy in one-way or two-way (round-trip) experiments have observables that depend on test functions $a(v^2)$, $b(v^2)$, and $d(v^2)$ but not on the synchronization procedure. He noted that “the synchronization of clocks played no role in the interpretation of experiments provided that one is careful to express the results in terms of physically measurable quantities”. Hence the synchronization is largely irrelevant.

The experiment in the paper (and I presume your proposed experiment) is measuring how the speed of light changes during a period of 24 hours as the Earth points the apparatus in different directions and they did measure a sinusoidal pattern.

The only reason for comparing changes over such periods of time not to measure "a" one way speed of light, but to search for differing one way speeds. Hence in my setup, instead of dual directional beams at different times, I use differing RPMs to establish a numerical value of c as defined by one, and only one clock, and one and only one tape measure. Hence my approach was to measure "a" one way speed where synchronization is irrelevant.

Even if you suppose my method is invalid you still have to invalidate E Riis et al, Phys. Rev. Lett, 60(2) (1988), and C. M. Will, Phys. Rev. D 45(2), 403-411 (1992), to justify the false claims on wiki.

 

[Dale]

I don't have a flash period, I have a light on 100% of the time. Neither do I have a t=0 anywhere period, or t= anything. Nor is there any pair of events that I measure for comparison.

I know. That is not the point.

The pure geometry does all that for me

The point is that the "pure geometry" depends on the synchronization convention. I.e. if the tube is straight under one synchronization convention then it is curved under another convention, and both predict the same experimental results.

Instead of this t= strawman when clearly i do not label t= to say what RPM something is rotating. I don't care when its rotating nor when the light was on.

Just because you don't label anything t doesn't imply that time is unimportant.

 

[ghwellsjr]

Yet here you are pretending I must not have even read it!
...
Even if you suppose my method is invalid you still have to invalidate E Riis et al, Phys. Rev. Lett, 60(2) (1988), and C. M. Will, Phys. Rev. D 45(2), 403-411 (1992), to justify the false claims on wiki.

Since you read the wikipedia article on "The one-way speed of light", why do say that I have to invalidate C. M. Will's paper when the article pointed out that:

In 1997 the experiment was re-analysed by Zhang who showed that, in fact, only the two-way speed had been measured. Will later confirmed that this conclusion was indeed correct.

And the paper by Riis was not claiming to measure the value of the one-way speed of light, it was similar to the previous experiment we discussed.

But you are claiming to be able to measure the one-way speed of light with your apparatus but I'm confused by this:

Hence my approach was to measure "a" one way speed where synchronization is irrelevant.

Are you saying that your approach would measure a speed that is different from 299,792,458 m/s?

 

[my_wan]

Since you read the wikipedia article on "The one-way speed of light", why do say that I have to invalidate C. M. Will's paper when the article pointed out that:

And the paper by Riis was not claiming to measure the value of the one-way speed of light, it was similar to the previous experiment we discussed.

But you are claiming to be able to measure the one-way speed of light with your apparatus but I'm confused by this:

These approaches were designed not to measure the speed of light in either direction, but rather to measure an anisopy in two directions of light. Yet you are confused by my my attempt at correcting this. So first let's look at the criticisms of these designs. Here is the abstract by Israel Pérez, which Zhang referenced:

In[/PLAIN] this contribution the question of the isotropy of the one-way speed of light from an experimental perspective is addressed. In particular, we analyze two experimental methods commonly used in its determination. The analysis is aimed at clarifying the view that the one-way speed of light cannot be determined by techniques in which physical entities close paths. The procedure employed here will provide epistemological tools such that physicists understand that a direct measurement of the speed not only of light but of any physical entity is by no means trivial. Our results shed light on the physics behind the experiments which may be of interest for both physicists with an elemental knowledge in special relativity and philosophers of science.

So why is my not closing paths in the setup I outlined so confusing?

Are you saying that your approach would measure a speed that is different from 299,792,458 m/s?

It bothers that that you would use the word "would" in red, simply on the grounds that it implies I am making a claim that the two-way light speed differs from the one way speed. Even in the context of GR, where GR doesn't hold light speed at an absolute constant, the speed is the same in both closed directions from anyone frame. GR has effectively the same contraction factor LET style transforms posit. The difference being that these transforms LET style theories invoke correspond to gravitational distortions in GR.

So before answering your question, to preempt a strawman as seems warranted, let's look at speed and distance variances that can be measured. If we are talking about a length contraction of some factor which exactly corresponds to an inverse time dilation factor $\Delta L \equiv 1/\Delta t$, then (unless you want to invoke coordinate dependence) the notion that you are even talking about a different distance in any local frame is moot. Measurability will strictly be dependent on a local interval in which the measurement is performed that differs from the intervals of the local space being measured. Not possible in a local measurement. Under GR these transforms are allowed, even required for gravitational effects. Thus in GR you have have a depth of field over a given distance with varying relational lengths. Yet comparing lengths in both directions will still be the same even if the speed of light is not.

So for GR type distance variations, which can't be measured via speed comparisons with closed paths, yes it will measure a differing speed of light. For interval type measurements, where distance is strictly defined by a choice of units under which $\Delta L \equiv 1/\Delta t$ is constant, no such measurement is possible. This later case is exactly the specified by SR with our inertial assumptions. Hence I do not expect the experiment to measure squat, as the "would" in your question implies. However, it does measure the one way light speed. There are two ways to get a speed c measure that differs from c, the first being fairly absurd but technically valid. (1) If an only if $\Delta L$ and $1/\Delta t$ was not separably constant in the manner specified by SR in a contiguous inertial space. (2) In situations, such as defined by GR, where $\Delta L$ and $1/\Delta t$ covaries over the space of $L$.

Given the above qualifications of what constitutes a measurement of speed c, yes, in situations where $\Delta L$ locally varies over $L$ or locally $\Delta L \neq 1/\Delta t$ in violation of SR, the measurement I describe will measure c different from 299,792,458 m/s. The later case is fairly absurd, though postulated by some. The former case is a standard part of GR, in which much of the spacelike interval $\Delta L$, on which the measurement depends, is not local to the frame in which the measurement is performed. Relativity then predicts that there must then exist a varying gravitational potential somewhere across $\Delta L$ even if the endpoints are effectively in flat spacetime.

The setup I defined is in fact a one-way measure light speed, not simply a comparison of speeds from both directions as in the referenced experiments.

 

[my_wan]

One other remark I have about Israel Perez's paper in the European Journal of Physics:
http://arxiv.org/abs/1102.4837

From[/PLAIN] this analysis representative expressions of the problem will be derived for the one-way and two-way speed of any physical entity (PE).

Although not explicitly stated here, the notion of labeling speed as a physical entity (PE) is implied. It cannot even mechanistically be labeled a physical variable in any strict sense even with purely Galilean transforms. I often use the kinetic energy of a pair of meteors to illustrate this, but this obviously also applies to speed. Like asking which if either meteor has a speed of 0. Speed is not a PE, it is the product of a coordinate choice. It seems to me that often what is being chased with one-way light speed arguments is a speed which is supposed by definition to constitute a PE. Though the Galilean linearity of simultaneity makes ignoring the facts trivial, speed labeled as a PE is not even entirely defensible under Galilean relativity. It's a coordinate choice, not a PE.

 

[Dale]

Speed is not a PE, it is the product of a coordinate choice.

Then how do you think that your device can measure it independently of the simultaneity convention which is part of your coordinate choice? You seem to be arguing against the key point you are making.

Suppose we have a theory where the one-way speed of light in the +x direction is infinite and the one way speed of light in the -x direction is .5 c and the speed of light is c in the y and z directions and distances are unchanged wrt standard SR. If we have a standard coordinate system T,X,Y,Z in units where c=1 then our non-standard system is:
t=T-X
x=X
y=Y
z=Z

Do you see how this is nothing more than a change in simultaneity and how your device cannot distinguish between these two simultaneity conventions?

 

[my_wan]

Then how do you think that your device can measure it independently of the simultaneity convention which is part of your coordinate choice? You seem to be arguing against the key point you are making.

Suppose we have a theory where the one-way speed of light in the +x direction is infinite and the one way speed of light in the -x direction is .5 c and the speed of light is c in the y and z directions and distances are unchanged wrt standard SR. If we have a standard coordinate system T,X,Y,Z in units where c=1 then our non-standard system is:
t=T-X
x=X
y=Y
z=Z

Do you see how this is nothing more than a change in simultaneity and how your device cannot distinguish between these two simultaneity conventions?

Of course, but look at what you have attributed the anisotropy to, the time component. What exactly do you mean to say when you attribute a metric (coordinate choice) to a coordinate variable that you are seeking to measure? In what way does the model used to define this variable as something distinct from the product of a coordinate choice? Even restricted solely to Galilean relativity, in what way does this model distinguish the coordinate designation from the coordinate choice induced location of kinetic energy? It sounds to me like what is being asked for, without explicitly saying so, is a measurement proving which of two meteors classical kinetic energy resides in. That's absurd even under purely Galilean relativity.

These questions are highly non-trivial and must be addressed to even ask the question. You cannot impose coordinate dependence just because of some vague notion that Newtonian kinetic energy must have some specific location, which it did not even prior to Einstein. So why then attempt to impose on classical mechanics a frame independent location that classical mechanics could not provide prior to Einstein?

If you want a better answer provide a better specification of what it is you want measure. Distance is relational construct, like kinetic energy, as is time. Do you wish explicitly postulate that space and time are measurably independent of the mechanistic constructs we measure it with? I do not get, after all the explanation provided, why you would then ask me to characterize a claim of a variance without squat of a description of what that variance relates to. Do you not see that your question implies, without specifying so, an attempt to get me to say I can physically measure a mechanistic difference between two coordinate choices? Do you not see that being a coordinate choice is not even a different distance, but merely a conversion like English to metric?

Yet under some circumstances the same question is an actual physical effect, rather than a coordinate choice, and leads to very real differences. So why do you not specify the circumstances if it can obviously go either way depending on those circumstances? Just like with t coming back to a son older than yourself is a very real possibility. Are you trying to say, since a coordinate choice is not a physical effect, you can't possibly end up older than your son? Throwing out a raw variables (x,y,z,t) with 0 context and asking for an either/or is a strawman. A very boring strawman.

 

[my_wan]

Here is an interesting and perfectly valid perspective:
http://Newton.umsl.edu/run//traveler.html

 

[Dale]

Of course, but look at what you have attributed the anisotropy to, the time component.

Then propose an alternative which:
A) has a non isotropic one way speed of light
B) has an isotropic two way speed if light equal to c
C) does not attribute the anisotropy to the time component

I am not aware of any such alternative, which is why I have claimed that choosing the one way speed off light is the same as specifying your synchronization convention. But if you are aware of alternatives then I would be glad to learn.

 

[my_wan]

Then propose an alternative which:
A) has a non isotropic one way speed of light
B) has an isotropic two way speed if light equal to c
C) does not attribute the anisotropy to the time component

I am not aware of any such alternative, which is why I have claimed that choosing the one way speed off light is the same as specifying your synchronization convention. But if you are aware of alternatives then I would be glad to learn.

Though I doubt it the question sounds like you didn't get past the first sentence. It really makes no difference which variable you pick. Given the inverse relation between space and time isn't saying the time varied directionally the same as saying space varied directionally? When you said "nothing more than a change in simultaneity" in the original question, wasn't that equivalent to saying nothing more than a change in coordinate choices? Time and simultaneity are meaningless without a space over which it operates. So implicitly when you attached an operator to the time component you implied the inverse of that operator could equally well apply to the (x,y,z) components.

This is what I was getting at when I said "what do you mean [...]". This entails that the inverse of the anisotropic time component can equally be applied to the spatial component. Yet if applied to the spatial components it is wrong to also apply it to the time component in that same frame under SR. So which of those alternatives to you want to assume, or do you want to assume space and time are not precisely inversely related?

So that's 3 choices and the questions that's been asked of me didn't even explicitly specify one, even though I went over this already. Then when the test is objected to no specifications for what it is you presumed I thought the test was for in the first place. Yet I'm somehow supposed to psychically determine how to answer these questions again without any specification or acknowledgment, rebuttal, etc., of my repeated explanations.

Tell me I am allowed to assume GR and I'll tell exactly what I would expect the test I described to be able to accomplish, both in terms of anisotropic clock, distance, and a measure of $c \neq 299,792,458 m/s$. But just say "it" can't be done tells me squat about what "it" is. What others have posited as anisotropy doesn't in itself make the claim any more meaningful than saying 1 inch $\neq$ 2.54cm because 1 < 2.54. Yet you still expect me to make an absolute claim about 1 and 2.54 without saying squat about what those 2 numbers represent. BS.

 

[Dale]

Given the inverse relation between space and time isn't saying the time varied directionally the same as saying space varied directionally?

Not if you want to keep the two-way speed of light isotropic and equal to c.

So implicitly when you attached an operator to the time component you implied the inverse of that operator could equally well apply to the (x,y,z) components.

Go ahead and try it and see what happens to the two-way speed of light. Maybe you will find an example where you can change the spatial coordinates and not change the two-way speed of light, I don't have a rigorous proof that it cannot be done, I just have never seen it.

 

[ghwellsjr]

I have been trying really hard to understand your experiment, my_wan, and then you made this comment in post #81:

The setup in http://arxiv.org/abs/1103.6086 is sufficiently close to what I proposed to qualify the general idea, and expressed in reference [7] (Phys. Rev. D 45, 403–411 (1992)) therein. It summed up the point quiet well with:

I read both these papers and discovered that the first one was not claiming to measure the one-way speed of light and the second one which was claiming to measure the one-way speed of light, was later discredited, and when I pointed that out to you, you responded with another paper http://arxiv.org/abs/1102.4837, which I thought you were doing to buttress your position but it shows why it is impossible to measure the one-way speed of light because all such measurements involve "close paths".

So why do you keep referencing papers that you later denounce? Where is the paper that supports your claim that you know how to measure the one-way speed of light? I'm looking for the paper that you agree with 100% and will not denounce after I have read it and point out a discrepancy between it and your position.

Apparently, you think your measurement does not involve close paths, is this correct? Is this why all these papers have nothing to do with your idea (like the last one you referenced in post #107 which has absolutely nothing to do with anything in this thread)? Should I go back and try to understand your experiment to see if it has close paths?

 

[my_wan]

Not if you want to keep the two-way speed of light isotropic and equal to c.

Go ahead and try it and see what happens to the two-way speed of light. Maybe you will find an example where you can change the spatial coordinates and not change the two-way speed of light, I don't have a rigorous proof that it cannot be done, I just have never seen it.

Just choose any frame as if it is the valid frame and define the constancy of c an observational illusion resulting from the inverse relation between space and time. Coming back to a son older than yourself then looks like the consequence of that anisotropy. Hence time still has to inversely relate to space regardless of which frame or coordinate choice you choose.

It's a pointless exercise in labeling a certain coordinate choice physically real while changing the frame (coordinate choice) under which it is meaningful. Yet it seems seems as though that what people often do when their talking about exceeding c so they can travel many light years faster. Speed c already let's you get there at the same time you left, yet it's sometimes not excepted as "real" because people appear to interpret it as though time dilation just give the illusion that you got there the same time you left. As if Earth is the real frame of reference.

So the fact that you can define these anisotropies in c and call the failure to measure it, like getting many light years in moments, as an illusion created by time dilation is both trivial and pointless.

 

[my_wan]

I have been trying really hard to understand your experiment, my_wan, and then you made this comment in post #81:

I read both these papers and discovered that the first one was not claiming to measure the one-way speed of light and the second one which was claiming to measure the one-way speed of light, was later discredited, and when I pointed that out to you, you responded with another paper http://arxiv.org/abs/1102.4837, which I thought you were doing to buttress your position but it shows why it is impossible to measure the one-way speed of light because all such measurements involve "close paths".

The first papers were not originally referenced by me, nor was I aware of them specifically till they were referenced here. The commonality exist only in the use of geometry rather than clock synchronization as the basis for the measurement. I thought that was sufficiently close unil it became obvious, from Perez et al that the comparison of speeds is going to match even if the speed of light differs.

So why do you keep referencing papers that you later denounce? Where is the paper that supports your claim that you know how to measure the one-way speed of light? I'm looking for the paper that you agree with 100% and will not denounce after I have read it and point out a discrepancy between it and your position.

I did not denounce the paper. The "close path" objection is valid. It is valid simply because if the the speed of light changed to some value v the comparing v/v still gives you 1 just like c/c.

Apparently, you think your measurement does not involve close paths, is this correct? Is this why all these papers have nothing to do with your idea (like the last one you referenced in post #107 which has absolutely nothing to do with anything in this thread)? Should I go back and try to understand your experiment to see if it has close paths?

You present the "close paths" disproof, pretend I'm denouncing a paper I am not, then state the reason I neither rebutted the "close paths" nor denounced the paper cited and ask me if I mean what I've been saying all this time.

Here is a picture:

 

[my_wan]

Now looking at that picture, is it not obvious that given some rotation differing speeds of light will change the amount of light detected at the detector?
Is it not obvious that "closed paths" are not being used?

 

[Dale]

Just choose any frame as if it is the valid frame and define the constancy of c an observational illusion resulting from the inverse relation between space and time. Coming back to a son older than yourself then looks like the consequence of that anisotropy. Hence time still has to inversely relate to space regardless of which frame or coordinate choice you choose.

Huh? Can you show what you mean here with an example?

 

[Dale]

Now looking at that picture, is it not obvious that given some rotation differing speeds of light will change the amount of light detected at the detector?
Is it not obvious that "closed paths" are not being used?

Is it not obvious to you that the picture itself depends on the synchronization convention?

 

[my_wan]

Huh? Can you show what you mean here with an example?

Do you mean to ask me to give an example of the fact that the physics is indepent of the coordinate choice? Newtonian physics restricted validity to a particular coordinate choice. Though Galilean transforms were allowed to translate between coordinate choices it was not always generally appreciated that these transforms allowed coordinate independence formulations in Newton's time. Ostensibly this wasn't a priority since it was so easy to presume simultaneity and space were absolute measurables. Relativity required these transforms to take center stage because the absolutes could not be maintained. Yet even with purely Galilean transforms the same coordinate independence required by relativity actually makes classical physics simpler.

Take the dilation factor $\gamma$. In SR $\gamma$ apply to time from one perspective and space from another viewing the exact same physical system. It makes no physical difference whether you define the capacity at near c to travel to Alpha Centauri in a couple of hours a result of time dilation or spatial contraction, yet mathematically you can't both by $\gamma$ from a single frame and get the right answer. Either is fine, both is wrong. Just like it makes no difference classically which Galilean frame you chose so long as you mathematically maintain that choice, or explicitly provide the transform. Just like it makes no difference which of two meteors you assign the kinetic energy to, but you can't assign the total to both.

Is that example enough, simply choose $\gamma$ to operate on space in one case, and on time in an physically equivalent case?

Is it not obvious to you that the picture itself depends on the synchronization convention?

Point it out to me, because I'm lost unless your want to make some absurd classical assumptions that cannot even stand scrutiny from a purely classical perspective.
Does it require the synchronization of two separate clocks? I say no, one single clock defining RPM, and one single yardstick defining the distance light has to travel to get detected before getting blocked. If, with sufficient resolution, you measure the speed of light as it travels straight down a gravitational potential then I fully expect it to appear as though $c > c$. Pointed up a gravitational potential I fully expect it to measure $c < c$ with the same apparatus. If you think I expect c to differ from c in an otherwise inertial frame by virtue of some medium lacking inertial effects it would be absurd.

Suppose instead of choosing between operating on space or time with some $\gamma$ you chose a frame in which some fraction operated spatially and some fraction on time. This is allowed, but the problem is that is such cases $\gamma_1 + \gamma_2$ cannot add up to the original $\gamma_{total}$. Is this unique to SR? No. If you choose a Galilean frame in which some fraction of $e_k$ is apportioned to both meteors then $e_k + e_k$ cannot add up to $e_{k(total)}$ as defined by the Galilean frame associated with either meteor.

It still seems to me that it is implicitly assumed that classical physics is coordinate independent, without recognizing that the formulation of it is in fact explicitly coordinate dependent. Then requiring me to physically measure the effects of a coordinate choice, due not to coordinate dependence, but rather a coordinate dependent formulation, in order to prove a one-way speed measure. I say no, it's an absurd distortion of logic. Yet the one-way measure is there nonetheless, even if it's not going to give a value other than c in an inertially uniform space.

 

[Dale]

Is that example enough, simply choose $\gamma$ to operate on space in one case, and on time in an physically equivalent case?

I was asking for a concrete example of a coordinate system which:
A) has a non isotropic one way speed of light
B) has an isotropic two way speed if light equal to c
C) does not attribute the anisotropy to the time component

I don't believe that such a system exists, but you seem to think that you could derive one from my example of post 105 simply by "the inverse relation between space and time". I don't get what you are saying with that, so a concrete example of such a coordinate transformation would be helpful.

 

[Dale]

Point it out to me

So, assume that we use the synchronization convention of post 105. Then the geometry of your tube changes as shown in the attachment.

 

[my_wan]

I was asking for a concrete example of a coordinate system which:
A) has a non isotropic one way speed of light
B) has an isotropic two way speed if light equal to c
C) does not attribute the anisotropy to the time component

I don't believe that such a system exists, but you seem to think that you could derive one from my example of post 105 simply by "the inverse relation between space and time". I don't get what you are saying with that, so a concrete example of such a coordinate transformation would be helpful.

In post #117 I give a very real and measurable example, involving a gravitational potential. Here's my problem with your request in general: When challenged to define a way to measure a one-way speed I mentioned how meaningless it was, but was challenged anyway. Then I'm accused of taking the physical meaning as somehow absolute. Then references are brought up to rebut it, so I allow variation to make it more clear. I'm then accused of accepting the reference as if it fully represented what I described. When I explained why it wasn't I was accused of rejecting the validity of the references. I explained again. In the meantime I was accussed of rejecting my own references, which were not even my own, but posted by others, nor did I reject their validity.

So, I can damn near guarantee that as soon as I submit to your request I will be accused of claiming it is absolutely real, and accused of trying to measure the this made up coordinate choice, then accused of rejecting my own coordinate your trying to demand I make up.

Now, if I've damn near written a book here trying to explain that a coordinate choice is not a physical choice. Yet your busy trying to goat me into constructing some BS coordinate choice for what? Unless the whole purpose is to somehow try to pin these BS accusations on me that I am somehow trying to defend the absolute physical reality of some BS coordinate choice. If there was a point I would do it anyway, yet it has no more of a point than a coordinate choice that puts the Earth at the center of the solar system.

So, assume that we use the synchronization convention of post 105. Then the geometry of your tube changes as shown in the attachment.

And so why did you divert the debate, with a complete lack of a response, pages back where I explained why this was a moot issue? I'll say it again: The fact that you can choose another equally valid coordinate choice, i.e., choose a differing synchronization convention that is consistent with SR that gets the same results with Einstein's synchronization convention is just another non-physical coordinate choice. It is NOT a required coordinate choice to get the same physical prediction, only Galilean coordinates are required for that, even though the predictions are the same.

So unless you want to claim that this non-physical coordinate choice (synchronization convention) you have chosen is in fact a physical choice then so what. Only then you are stuck trying to explain why a purely Galilean coordinate choice gives the same answers. Hence this whole, it bends to create the illusion that a Galilean coordinate choice valid implies that a coordinate choice is a physical thing in itself.

The only challenge I signed up for was not to prove any coordinate choice was a physical thing, only that with a single clock and a single tape measure a one way speed of light could be measured. It is not my problem if you want to insist on a specific coordinate choice from which you decide it's absolute physical meaning is derived.