Consistency of the speed of light

[Aether]

The game you are playing is clinging to the short end of the every-experiment-ever-performed stick.

As long as there remains a short end to cling to, then somebody should; but the ether end of the stick isn't really as short as some people say.

Every experiment ever performed on the subject requires no ether, but you'd prefer to assume that there are some experiments we haven't thought of yet that might show it does exist.

Do you play slots...?

98% of the matter-energy in the universe is still missing...isn't a 98% payout considered to be a pretty good deal when it comes to playing slots?

Yeah, I'm an engineer, not a physicist, but the way I see the issue is that as science progresses, the "box" that ether theory can fit into gets smaller and smaller and aether theorists bob and weave and back away further and further into the depths of that box, never wanting to acknowledge that there is an entire universe outside that box that they'd prefer not to live in.

Ether theory is empirically equivalent to SR. It is flat wrong to claim that the constancy of the speed of light has ever been proved by experiment.

What's the difference? Assuming that the speed of light is constant, then $$x_0=\int{c(t)dt}$$ reduces to $$x_0=c_0t$$...but if the speed of light is not constant then these two equations do not give the same result for $$x_0$$. Directly measuring $$x_0$$ is the future experiment that I have in mind.

 

[ZapperZ]

Which, if any, of your citations do not reference the paper that I cited? Which, if any, of your citations explicitly contradict the paper that I cited? Still, in the past I have collected as many of the papers cited in your journal (and their cited references) as I could get my hands on, and appreciate the list that you keep.

You seem to be ignoring what it is being cited for, and what these experiments are testing. For example, the Lipa paper clearly mentioned that they have come up with very severe limitations of the possible anisotropy of the M-S model. Furthermore, in a comment by Bay and White[1], and responded by Riis et al.[2], there clearly are questionable issues whether M-S model can account for Riis's 2-photon absoroption experiment.

However, in all of the papers that I cited, NOT ONE of them reach the conclusion that the postulate of SR has failed, and that they have found the extra terms of M-S model. NONE! You seem to use the fact that since M-S paper was cited, it has progressed beyond just being called a "test theory". It hasn't!

Zz.

[1] Z. Bay and J.A. White PRL v.62, p.841 (1989).
[2] Riis et al PRL v.62, p.842 (1989).

 

[Aether]

You seem to be ignoring what it is being cited for, and what these experiments are testing. For example, the Lipa paper clearly mentioned that they have come up with very severe limitations of the possible anisotropy of the M-S model. Furthermore, in a comment by Bay and White[1], and responded by Riis et al.[2], there clearly are questionable issues whether M-S model can account for Riis's 2-photon absoroption experiment.

OK, I'll look at that, but that exchange is 16 years old; why hasn't it been pursued since then?

However, in all of the papers that I cited, NOT ONE of them reach the conclusion that the postulate of SR has failed, and that they have found the extra terms of M-S model. NONE! You seem to use the fact that since M-S paper was cited, it has progressed beyond just being called a "test theory". It hasn't!.

Aren't they all looking for spatial anisotropy parameters? Which of these papers were looking for the three temporal parameters of the M-S model? The temporal coordinate $$x_0$$ can distinguish between SR and ether theory, but all of these experiments are looking only at $$x_1, \ x_2, \ and \ x_3$$ in vacuum.

 

[DrGreg]

The concept of speed depends on your definitions of distance and time. For an object that is static relative to the observer, these definitions are clear and unambiguous -- our pre-relativistic notions suffice. For a moving object, you need to have some mechanism for synchronising two clocks a distance apart; you cannot measure the time taken to travel from A to B unless the clocks at A and B (both static relative to the observer) have been synchronised in some way. And you can't measure the length of an object unless you measure the positions of each end "at the same time", whatever that means.

Therefore you cannot measure the speed of light from A to B unless you have already agreed a convention for synchronising clocks. The method that Special Relativity adopts assumes that the speed of light is constant. So if you measure the speed of light using this convention you are guaranteed to find it is constant. Within SR the speed of light is constant by definition. It's impossible to disprove unless you redefine what you mean by "speed" (or "distance" or "time").

However, you can unambiguously define the average speed of an object that travels from A to B and back to A again, relative to A. The total distance traveled and the total time taken can be measured using a single clock (A's) without any need for a synchronisation procedure. Experimental evidence does indeed confirm that the average speed of light from A to B to A is constant.

Let $(t_0, x_0, y_0, z_0)$ be an inertial frame. Define a new set of coordinates as follows:

$$t = t_0 / \gamma$$
$$x = \gamma (x_0 - v t_0)$$
$$y = y_0$$
$$z = z_0$$

(where $\gamma$ is defined in the usual way as $1/\sqrt{1-v^2/c^2}$). Do the maths and you will find that in this coordinate system the (one-way) speed of light is not constant but average A-to-B-to-A speed is still $c$. And in this coordinate system, all clocks agree on what is "simultaneous". In a nutshell, this is Lorentz ether theory and it works. It's just a very ugly theory, compared with SR, because it's not at all symmetric and the equations get much more complicated. The coordinates are not all mutually orthogonal and its has non-diagonal metric tensor

$$ds^2 = dx^2 / \gamma^2 + 2 v dxdt + dy^2 + dz^2 - c^2 dt^2$$

I have just demonstrated that it is possible for the one-way speed of light to vary without deviating from the experimental evidence the two-way average speed of light is constant. But I've done by sleight-of-hand by redefining what I mean by "speed" which is the only way it can be done.

 

[Aether]

In a nutshell, this is Lorentz ether theory and it works. It's just a very ugly theory, compared with SR, because it's not at all symmetric and the equations get much more complicated.

An ugly theory compared to SR, in the absence of any evidence for a locally preferred frame, OK. Constancy of the speed of light proven by experiment, NO.

 

[ZapperZ]

OK, I'll look at that, but that exchange is 16 years old; why hasn't it been pursued since then?

Oh puhleeze. You're complaining about a 16-year old exchange while you're citing a paper that's 28 years old? I can play that game too. If the M-S theory is THAT old, why hasn't it been accepted more readily already by now?

Zz.

 

[Aether]

Oh puhleeze. You're complaining about a 16-year old exchange while you're citing a paper that's 28 years old?

You said that

...there clearly are questionable issues whether M-S model can account for Riis's 2-photon absoroption experiment

So, with 16 years gone by since these "questionable issues" arose, is it not legitimate to ask where those threads lead to?

I can play that game too. If the M-S theory is THAT old, why hasn't it been accepted more readily already by now?

Zz.

M-S theory is widely accepted; everyone who is publishing tests of local Lorentz invariance seems to be using it and nobody is knocking it. There are a few typos in it though, and I have seen where those errors have propagated through a few papers.

 

[robphy]

M-S theory is widely accepted; everyone who is publishing tests of local Lorentz invariance seems to be using it and nobody is knocking it. There are a few typos in it though, and I have seen where those errors have propagated through a few papers.

A few words from http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html

Test Theories of SR
A test theory of SR is a generalization of the Lorentz transforms of SR using additional parameters. One can then analyze experiments using the test theory (rather than SR itself) and fit the parameters of the test theory to the experimental results. If the fitted parameter values differ significantly from the values corresponding to SR, then the experiment is inconsistent with SR. But more normally, such fits can show how well a given experiment confirms or disagrees with SR, and what the experimental accuracy is for doing so. This gives a general and tractable method of analysis which can be common to multiple experiments.

Different test theories differ in their assumptions about what form the transform equations could reasonably take. There are at present four test theories of SR:

Robertson,Rev. of Mod. Phys. 21, p378 (1949).
Edwards, Am. J. Phys. 31 (1963), p482.
Mansouri and Sexl, Gen. Rel. Grav. 8 (1977), p497, p515, p809.
Zhang, Special Relativity and its Experimental Foundations.​

Zhang discusses their interrelationships and presents a unified test theory encompassing the other three, but with a better and more interpretable parameterization. His discussion implies that there will be no more test theories of SR that are not reducible to one of the first three.

So, I think that it would be more correct to say that "M-S theory is widely accepted merely as a test theory of SR" (that is, a framework for testing SR).

 

[Aether]

So, I think that it would be more correct to say that "M-S theory is widely accepted merely as a test theory of SR" (that is, a framework for testing SR).

Here's Zhang's own summary of his book: "In particular, the simultaneity problem and slow transport of clocks are investigated in detail by means of the test theories of special relativity. In the second part, variant types of experiments performed up to now are analyzed and compared to the predictions of special relativity. This shows that the experiments are a test of the two-way speed of light, but not of the one-way speed of light."

I ordered copy of Zhang, and hope that the promise of "a unified test theory encompassing the other three, but with a better and more interpretable parameterization" is fulfilled.

 

[ZapperZ]

You said thatSo, with 16 years gone by since these "questionable issues" arose, is it not legitimate to ask where those threads lead to?

M-S theory is widely accepted; everyone who is publishing tests of local Lorentz invariance seems to be using it and nobody is knocking it.

But not in the way YOU imagined it. The "extra terms" beyond SR in M-S theory has never cropped up. They have never been measured. And in none of the experimental papers I cited have there been any indication by the authors that these verify the existence of ANY ether, no matter how one "synchronizes" one's clock.

The conclusions in each of the papers are glaringly clear. Why you think this agrees with your ether point of view, I have no idea.

Zz.

 

[Aether]

But not in the way YOU imagined it. The "extra terms" beyond SR in M-S theory has never cropped up. They have never been measured. And in none of the experimental papers I cited have there been any indication by the authors that these verify the existence of ANY ether, no matter how one "synchronizes" one's clock.

All measurements are so far consistent with both SR and Lorentz ether theory (with the possible exception of the example from 1989 that you gave), but you are implying that all measurements select SR over Lorentz ether theory.

The conclusions in each of the papers are glaringly clear. Why you think this agrees with your ether point of view, I have no idea.

The conclusions of each of the papers can't be stretched any farther than to say that SR is empirically equivalent to Lorentz ether theory (LET). What they fail to do is to select LET over SR, but you are claiming that they somehow select SR over LET and that is not true either.

 

[DrGreg]

An ugly theory compared to SR, in the absence of any evidence for a locally preferred frame, OK. Constancy of the speed of light proven by experiment, NO.

Experiments never prove a theory true, they can only ever succeed or fail to disprove a theory.

So there is always the possibility that one day somebody will find circumstances in which the two-way speed of light is not constant. If that day ever comes then SR or GR will have been proven not be a valid model in those circumstances.

Theories are models of reality, not reality itself. They tend to make simplifying assumptions e.g. that friction can be ignored, or that speeds are slow relative to light, or that gravity can be neglected, or that matter is distributed as a continuous density (instead of being particulate). That doesn't invalidate the theory as long as you are aware of its limitations.

Maybe one day we will need to reinvent the ether at quantum level or in some other extreme circumstances. If that ever happens, relativity will still be a valid approximation in the circumstances that aren't extreme.

 

[Perspicacious]

A test theory of SR is a generalization of the Lorentz transforms of SR using additional parameters. …

Different test theories differ in their assumptions about what form the transform equations could reasonably take. There are at present four test theories of SR. http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html

Tom Roberts is wrong. Guido Rizzi, Matteo Luca Ruggiero and Alessio Serafini are right. What Mansouri and Sexl have is just the Lorentz transformation with a more general synchronization procedure.

It is possible to reset the clocks of the Mansouri and Sexl synchronization and get back to the Lorentz transformation. It’s silly to call generic resynchronizations of the Lorentz transformation a generalization of SR.

http://arxiv.org/abs/gr-qc/0409105

 

[Aether]

SR and LET are empirically equivalent. It is impossible to prove SR by experiment, and impossible to disprove LET by experiment. So, I suspect that there is some philosophical principle that places the burden of proof on the shoulders of LET. That's fine, but it doesn't license the disciples of Einstein to claim that the constancy of the speed of light has been proven by experiment.

 

[ZapperZ]

All measurements are so far consistent with both SR and Lorentz ether theory (with the possible exception of the example from 1989 that you gave), but you are implying that all measurements select SR over Lorentz ether theory.

The conclusions of each of the papers can't be stretched any farther than to say that SR is empirically equivalent to Lorentz ether theory (LET). What they fail to do is to select LET over SR, but you are claiming that they somehow select SR over LET and that is not true either.

Then you have NOTHING! You are faced with a theory that has tons of verification, have been successful in a lot of applications, including the accurate correction to many band-structure calculations, etc... etc. Given two theories, and one that has been adopted universally and used in REAL application, you chose THE OTHER?

And you see nothing wrong with this?

Zz.

 

[ZapperZ]

SR and LET are empirically equivalent. It is impossible to prove SR by experiment, and impossible to disprove LET by experiment.

It is not! There are two extra terms in M-S theory regarding the ratio between $$c(\theta , v)/c$$. The Lipa et al. results have put severe limits on the value of those two extra terms! To claim no one has gone looking for it is false.

Zz.

 

[pervect]

All measurements are so far consistent with both SR and Lorentz ether theory (with the possible exception of the example from 1989 that you gave), but you are implying that all measurements select SR over Lorentz ether theory.

The job of making experimental predictions should be the responsibility of the Lorentz Ether theorists.

Unfortunately, they appear to be a very diffuse group, who while they all use the same name, don't actually all believe the same thing.

If, as in one subsection of the LET group claims, there is no difference between LET and relativity, then it is not a different theory than relativity.

If, as in another subsection of the LET group claims, there is a difference between LET and relativity, it is (or should be) up to the LET theorists to pin down what experimental predictions the theory makes, so the theory can be tested.

Part of the problem is that I don't think LET actually has any qualified theorists who write refereed papers that one can point to as "the" LET theory, rather it has only a muddle of individuals who have somehow given the same name to their differing ideas.

 

[Aether]

It is not! There are two extra terms in M-S theory regarding the ratio between $$c(\theta , v)/c$$. The Lipa et al. results have put severe limits on the value of those two extra terms! To claim no one has gone looking for it is false.

Zz.

"Summarizing these results we may say that the following statement is in perfect agreement with all experimental evidence: A preferred system of reference, the ether system, exists." - Mansouri & Sexl I

"All experiments can be explained either on the basis of special relativity or by an ether theory incorporating time dilation. This demonstrates again the impossiblity of an "experimentum crucis" deciding between ether theories and the special theory of relativity." - Mansouri & Sexl - II

"First-order tests cannot be used to distinguish between special relativity and ether theories, as has sometimes been stated. No such "experimentum crucis" is possible in principle, since the two classes of theories can be transformed into one another by a change in conventions about clock synchronization..." - Mansouri & Sexl - II

"According to these authors this experiment [similar to the Michelson-Morley experiment] is able to decide between the special theory of relativity and an ether theory incorporating Lorentz contraction and time dilation. As we have shown quite generally in the first and second parts of this paper such a distinction is impossible in principle." - Mansouri & Sexl III

 

[Perspicacious]

The job of making experimental predictions should be the responsibility of the Lorentz Ether theorists.

Unfortunately, they appear to be a very diffuse group, who while they all use the same name, don't actually all believe the same thing.

If, as in one subsection of the LET group claims, there is no difference between LET and relativity, then it is not a different theory than relativity.

If, as in another subsection of the LET group claims, there is a difference between LET and relativity, it is (or should be) up to the LET theorists to pin down what experimental predictions the theory makes, so the theory can be tested.

Part of the problem is that I don't think LET actually has any qualified theorists who write refereed papers that one can point to as "the" LET theory, rather it has only a muddle of individuals who have somehow given the same name to their differing ideas.

Very well said. I agree.

 

[Aether]

I have scanned-in the three Mansouri & Sexl papers. If anyone is interested but doesn't have easy access to a library with the journal, let me know and I'll give you a web address where you can go to download the file (it is about 143MB); right click on the link, and save. It is in MS Word .doc format, and it comes from my working copy so please excuse that it has been heavilly highlighted and is somewhat marked up and wrinkled.

 

[ZapperZ]

"Summarizing these results we may say that the following statement is in perfect agreement with all experimental evidence: A preferred system of reference, the ether system, exists." - Mansouri & Sexl I

"All experiments can be explained either on the basis of special relativity or by an ether theory incorporating time dilation. This demonstrates again the impossiblity of an "experimentum crucis" deciding between ether theories and the special theory of relativity." - Mansouri & Sexl - II

"First-order tests cannot be used to distinguish between special relativity and ether theories, as has sometimes been stated. No such "experimentum crucis" is possible in principle, since the two classes of theories can be transformed into one another by a change in conventions about clock synchronization..." - Mansouri & Sexl - II

"According to these authors this experiment [similar to the Michelson-Morley experiment] is able to decide between the special theory of relativity and an ether theory incorporating Lorentz contraction and time dilation. As we have shown quite generally in the first and second parts of this paper such a distinction is impossible in principle." - Mansouri & Sexl III

Then I suggest you or them write a rebuttal to the Lipa et al. paper in PRL, and a number of other papers that I cited. The Lipa paper has been out since 2003 and NO ONE has challenged either their interpretation or results. It takes nothing to whine about it on here. Put your name and reputation on the line and do it officially if you think there's any credibility in what you believe in.

Zz.

 

[Aether]

Then I suggest you or them write a rebuttal to the Lipa et al. paper in PRL, and a number of other papers that I cited. The Lipa paper has been out since 2003 and NO ONE has challenged either their interpretation or results. It takes nothing to whine about it on here. Put your name and reputation on the line and do it officially if you think there's any credibility in what you believe in.

Zz.

Zz, as I understand this, those two terms could be exactly what is predicted by SR and that still wouldn't select out SR over LET because the two theories transform into each other by a change in conventions about clock synchronization. Please stop referencing what I "believe in", and deal with the fact that SR and LET are empirically equivalent.

Lipa et al. references M-S without complaint, but they also reference two more recent (2001 & 2002) papers from Kostelecky & Mewes (KM) that are supposed to have an even more general transformation than M-S. I'll go to the library today and get the KM papers; if they are as thorough as M-S, then I'll be happy to start using them in their place.

 

[pervect]

Zz, as I understand this, those two terms could be exactly what is predicted by SR and that still wouldn't select out SR over LET because the two theories transform into each other by a change in conventions about clock synchronization. Please stop referencing what I "believe in", and deal with the fact that SR and LET are empirically equivalent.

"LET" is a name for a theory which is unfortunately not very well defined, as far as I can tell. If you've got references that have a definitive defintion of what the theory actually is, please do post. Note that I took a quick look at the link you did post, however it displayed scanned text on my screen running up and down, making it extremely hard to read. (I use 602 Text to read .doc format files, I don't know if that makes any difference or not). So I doubt I'll be reading it unless I find a way to make it run right-left.

While it is possible that one or more of the two papers you cite make an outright error, the more probable state of affairs is that they each have different defintions of exactly what "LET" really means (what the fundamental assumptions of the theory are).

I think more care needs to be taken to make sure that the authors are *really* talking about the same theory.

If we take your defintion of LET as "a theory that is mathematically equivalent to SR", then it really isn't very clear why you find LET interesting at all. If you find it easier to understand the theory in its new formulation, great, but the general tone of your question doesn't seem to be that of an enlightened person who is trying to explain a simpler way of doing something. Rather it seems like you are experiencing doubts about something, but the only thing that I can see to doubt is the details of the formulation of LET.

 

[Aether]

"LET" is a name for a theory which is unfortunately not very well defined, as far as I can tell. If you've got references that have a definitive defintion of what the theory actually is, please do post. Note that I took a quick look at the link you did post, however it displayed scanned text on my screen running up and down, making it extremely hard to read. (I use 602 Text to read .doc format files, I don't know if that makes any difference or not). So I doubt I'll be reading it unless I find a way to make it run right-left.

The images are scanned photos of each page of the paper, so a text editor is not going to work. Is there a better format, like pdf that would be easier for you to view?

While it is possible that one or more of the two papers you cite make an outright error, the more probable state of affairs is that they each have different defintions of exactly what "LET" really means (what the fundamental assumptions of the theory are).

I think more care needs to be taken to make sure that the authors are *really* talking about the same theory.

If we take your defintion of LET as "a theory that is mathematically equivalent to SR", then it really isn't very clear why you find LET interesting at all. If you find it easier to understand the theory in its new formulation, great, but the general tone of your question doesn't seem to be that of an enlightened person who is trying to explain a simpler way of doing something. Rather it seems like you are experiencing doubts about something, but the only thing that I can see to doubt is the details of the formulation of LET.

Until there is a confirmed detection of a locally preferred frame, then LET and SR are empirically equivalent; if there is ever such a detection, then LET takes charge. I would probably not care if that were the end of the story, however SR is not the end of the relativity story, not by a long shot. It is a starting point for everything else; a local approximation to reality. There are big problems on the largest scales with dark matter, dark energy, and on the smallest scales with the unification of QM, EM, and gravity, and more. That's what I'm really interested in, but applying SR can be something like trying to climb a greased flagpole (that's something that we sometimes try to do here in the US), take VSL as an example; SR forbids it by definition. It is flat wrong to claim that experiments constrain the speed of light to be forever constant; so I'm looking for the most efficient ways to argue that, and to model that.

It is not likely that there are other than a few typographical errors in M-S. This is what Kostelecky & Mewes, Phys. Rev. D, 66, 056005-4 (2002) have to say about M-S: "In this simple example, the transformation $$T^\mu_\nu$$ leaves invariant the rods and clocks, while $$\Lambda^\mu_\nu$$ leaves invariant the speed of light. Both are equally valid. In the frames related by $$T^\mu_\nu$$, observers agree on rod lengths and clock rates but disagree on the velocity of light. Moreover, the velocity of light is no longer isotropic as measured by these rods and clocks. In contrast, observers related by Lorentz transformations agree that light propagates isotropically with speed 1 but may disagree on rod lengths and clock rates. The description is a matter of coordinate choice, and one can move freely from one to the other using $$T^\mu_\nu$$, $$\Lambda^\mu_\nu$$, and their inverses."

 

[pervect]

The images are scanned photos of each page of the paper, so a text editor is not going to work. Is there a better format, like pdf that would be easier for you to view?

I think pdf would work much better.

Until there is a confirmed detection of a locally preferred frame, then LET and SR are empirically equivalent; if there is ever such a detection, then LET takes charge.

I would probably not care if that were the end of the story, however SR is not the end of the relativity story, not by a long shot. It is a starting point for everything else; a local approximation to reality. There are big problems on the largest scales with dark matter, dark energy, and on the smallest scales with the unification of QM, EM, and gravity, and more. That's what I'm really interested in, but applying SR can be something like trying to climb a greased flagpole (that's something that we sometimes try to do here in the US), take VSL as an example; SR forbids it by definition. It is flat wrong to claim that experiments constrain the speed of light to be forever constant; so I'm looking for the most efficient ways to argue that, and to model that.

Opinions vary - I find that trying to apply non-SR theories is like trying to "climb a greased flagpole". Metaphorically, anyway, I've never actually tried to do that :-)

In my opinion, if LET wants to accomplish something, it has to at least suggest some experiments which might allow one to detect some sort of preferred frame. If it is just another formulation of SR, it's probably not going to catch on, unless it is simpler to teach (but I suspect that the current formalism is much simpler). It may have a small niche for those who can't adjust their personal philosphies to deal with SR.

It is not likely that there are other than a few typographical errors in M-S. This is what Kostelecky & Mewes, Phys. Rev. D, 66, 056005-4 (2002) have to say about M-S: "In this simple example, the transformation $$T^\mu_\nu$$ leaves invariant the rods and clocks, while $$\Lambda^\mu_\nu$$ leaves invariant the speed of light. Both are equally valid. In the frames related by $$T^\mu_\nu$$, observers agree on rod lengths and clock rates but disagree on the velocity of light. Moreover, the velocity of light is no longer isotropic as measured by these rods and clocks. In contrast, observers related by Lorentz transformations agree that light propagates isotropically with speed 1 but may disagree on rod lengths and clock rates. The description is a matter of coordinate choice, and one can move freely from one to the other using $$T^\mu_\nu$$, $$\Lambda^\mu_\nu$$, and their inverses."

Well here's my take on isotropy via a physical example, giving some examples about what is involved in making such a coordinate choice.

Let us suppose that we decide that it is perfectly OK to use an arbitrary clock synchronization to determine speeds, and that we decide to synchronize our clocks by noontime, when the sun is directly overhead. (This is a continuous version of the "time zones" used in the US).

Now, let's compare airplanes flying east-west and west-east with our new clock synchronization methods. We find that airplines flying west travel much faster than the same airpanes flying east, even after we correct for the prevailing winds (which are significant, but I want to ignore this issue).

When we measure the speed of light, we find that it actually arrives before it left with this defintion of synchronization going west - making it have a negative speed (ouch). And it (light) is very pokey going east, traveling verrry slowly.

We also find that the physical expression of momentum depends on the direction one is moving.

With our old definiton of speed, in stil air we could say that the airplanes were going 600 mph east, and 600 mph west, and when they collided, they fell straight down to the ground with no net average velocity.

WIth our new definition of speed, the speeds of identical airplanes flying in still air east-west and west-east are *not* the same. Let's make this concrete, and say that the airplines are going something like 200 mph east, and 1000 mph west in our new system of measurement.

But these airplanes still fall straight down to the ground when they collide (well, that's idealized, but their pieces don't have any net average velocity, and if we could build the airplanes strong enough so that they didn't break apart, we would observe them falling straight down).

Now if we look at two identical airplines colliding with the same velocity, using our new system of synchroniation we find that when they have the same mass and speed, they do not have the same momentum, and that airplanes moving "at the same speed" (with our NEW defijntion of speed) in opposite directions don't fall straight down when they collide.

THe point of this exercise is that clock synchronizations don't really make new physics, which is exactly what the authors you quote are saying.

[add] By this I mean that there are no different experimental predictions. Clearly, Newton's laws have a different appearance when we adopt a non-isotropic clock synchronization method. But the behavior of the actual colliding masses (airplanes in this example) is unchanged.
[end add]

Furthermore, working with clocks synchronized in an anisotropic manner yields anisotropic behavior of physical bodies (like airplanes) as well as anisotropic behavior of light. The clock sychronization that makes light act isotropically is the same clock synchronization that makes airplanes and other physical bodies act isotropically (i.e. come to rest when equal masses at equal velocities coming from opposite directions have an inelastic collision).

 

[Didyoueatpaintchips]

With all these posts no one has stated the reason that SR was needed in the first place. Also how could a forum not include posts from people who don't agree with einstein. This is truly intellectual censorship. No wonder we have had to endure 100 years of relativity, this is what all of the colleges also do, so there are no new ideas.

First I'll answer my first question; Why was relativity needed at all? For that we need to go back to the Michaelson Morley experiment. All of great minds at that time, believed that the Earth traveled through space, in a so called aether. This aether carried light waves at the speed of light in space. So if the Earth was moving in relation to this aether, then the observed speed of light on the Earth would be c + v, where c is the constant speed of light in space, and v is the speed of the observer, in this case the Earth as it moves through so called aether. obser-c = c + v. Of course we know that they got a null result. No one could believe it. The greatest minds could not accept this. Let's see what this leads to, if you get a null result, what exactly is null? It is the velocity of the observer. This leads to this equation; v = constant of 0. Which means that no matter the velocity of the observer, relative to light his speed is 0. Since the observer is always a constant 0 velocity, then you need time and space to become variables. Which means you need relativity. Time and space had always been considered constant, and rightly so. I have much more to say but I'm not sure this is the right forum since it appears to be censored.

mike

 

[pervect]

With all these posts no one has stated the reason that SR was needed in the first place.

You'll find lots of posts on that topic if you look, but that wasn't the question. The short answer is "The negative results of the Michelson-Morley experiments".

Also how could a forum not include posts from people who don't agree with einstein. This is truly intellectual censorship. No wonder we have had to endure 100 years of relativity, this is what all of the colleges also do, so there are no new ideas.

Yep, we do have some forum guidelines here, which you've apparently read, though you've decided to disregard them. Please feel free to post your astounding intellectual ideas about why relativity is wrong to an unmoderated forum like, for example, usenet sci.physics.relativity, where "anything goes" and frequently does.

First I'll answer my first question; Why was relativity needed at all? For that we need to go back to the Michaelson Morley experiment.

Oh, I see you already knew. Then why the heck did you try and hijack thre thread to ask the answer to a question that you already knew, and disregard the forum guidelines to boot?

 

[Hans de Vries]

The conclusions of each of the papers can't be stretched any farther than to say that SR is empirically equivalent to Lorentz ether theory (LET). What they fail to do is to select LET over SR, but you are claiming that they somehow select SR over LET and that is not true either.

I've been looking at your doc which I turned into a readable version here:
(33 MB) http://chip-architect.com/physics/Mansouri&Sexl_2.doc I'll leave it here for 12 hours.


Aether,

Mansouri and Sexl make a statement that our world can be equally well
described by a transformation other then the Lorentz Transformation.
This is just as true as the statement that our world can be equally well
described by, say, for instance it's Fourier Transform. Although this is
mathematically correct, I is certainly not how we perceive our world.

We perceive non-simultaneity


Regards, Hans.

 

[Hans de Vries]

proof for non simultaneity via computer simulation.

I use images here to proof the non simultaneity of SR rather than math.
I can't make it any simpler.

A remarkable amount of physics can be extracted from the simple rule
that the wave front is always at right angles with the physical velocity,
regardless of the reference frame.

The left half of the image below shows a fast particle chasing a slower
particle with equal mass. The fast particle has a shorter deBroglie
wavelength. The *phase* speed of the faster particle is slower (as given
by $c^2/v$ ) While the *phase* speed of the slower particle is higher.

At the right half we see the same scene from a reference frame moving
upwards. The extra motion has a larger influence on the slower moving
particle. Its relative motion changes downwards more than the faster
particle. As one can see, the combination of Special Relativity and
Quantum Mechanics makes sure that the wavefronts are exactly at right
angles with the physical speed, exactly as one would intuitively expect.

It is only Special Relativity which can rotate wavefronts, and it does so
for both light and matter waves. A Galilean transformation keeps the
wavefronts always directed in the same direction! The mechanism through
which Special Relativity manages this is again via the non-simultaneity
of time.



Regards, Hans

 

[DrGreg]

Readers of this thread might find this article: Breaking Lorentz symmetry of interest. It is from Physics World, the magazine of the Institute of Physics, the professional body for physicists in Britain.

It mentions Mansouri-Sexl and puts their work into a wider context.

 

[Aether]

I think pdf would work much better.)

Can you read Hans' version? If not, I'll post a pdf. I made a .pdf first, but it was very large so I wen't for a .doc; it wasn't any smaller though.

Opinions vary - I find that trying to apply non-SR theories is like trying to "climb a greased flagpole". Metaphorically, anyway, I've never actually tried to do that :-)

In my opinion, if LET wants to accomplish something, it has to at least suggest some experiments which might allow one to detect some sort of preferred frame. If it is just another formulation of SR, it's probably not going to catch on, unless it is simpler to teach (but I suspect that the current formalism is much simpler). It may have a small niche for those who can't adjust their personal philosphies to deal with SR.

Suppose that LET turns out only to be useful as a waypoint (for some) on the philosophical journey to SR. Even so, what is the justification for tolerating false (however well intentioned) claims that the constancy of the speed of light is an empirically determined fact? Why not just state up front that partiality to SR is simply a matter of coordinate choice, and not an empirical necessity?

 

[ZapperZ]

With all these posts no one has stated the reason that SR was needed in the first place. Also how could a forum not include posts from people who don't agree with einstein. This is truly intellectual censorship. No wonder we have had to endure 100 years of relativity, this is what all of the colleges also do, so there are no new ideas.

This is utterly silly. I can show you one, two, three, etc. examples of "new ideas" that came out of "colleges". When was the last time you read PRL? Will this be sufficient to show that your statement here is FALSE?

It is the velocity of the observer. This leads to this equation; v = constant of 0. Which means that no matter the velocity of the observer, relative to light his speed is 0. Since the observer is always a constant 0 velocity, then you need time and space to become variables.

Say what? Relative to light, the observer's speed is ZERO? Do you know what you just said? Relative to me, my computer monitor has a speed of zero. We are both moving at the same speed then. You have just said the observer is moving at the same speed as light!

And this is your argument on why we needed SR? Oy vey! And to think colleges "censor" things like this! How dare they!

Zz.

 

[Aether]

I have a .pdf of Hans' reformatted version of the Mansouri&Sexl papers (8MB) that I can make available on request.

Readers of this thread might find this article: Breaking Lorentz symmetry of interest. It is from Physics World, the magazine of the Institute of Physics, the professional body for physicists in Britain.

It mentions Mansouri-Sexl and puts their work into a wider context.

Great article, thanks!

 

[Aether]

We perceive non-simultaneity

I don't think so, Hans. We actually perceive only dimensionless ratios (http://arxiv.org/abs/hep-th/0208093), and all judgements of simultaneity ultimately depend on one's choice of clock synchronization convention.

A remarkable amount of physics can be extracted from the simple rule that the wave front is always at right angles with the physical velocity, regardless of the reference frame.

Suppose that you are right, doesn't this "simple rule" amount to the choice of Einstein's clock synchronization convention?

 

[quantumdude]

I don't think so, Hans. We actually perceive only dimensionless ratios, and all judgements of simultaneity ultimately depend on one's choice of clock synchronization convention.

How's that? Right now, sitting at my desk, I've just observed someone tying his shoe, followed by someone else clicking a mouse. Why do I need a clock synchronization scheme to say which one comes first? And if some other observer goes zipping by at high speed and observes the events in reverse order, why would he need a clock synchronization scheme to say the opposite?