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Consistency of the speed of light 
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#55
Sep1405, 05:48 AM

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I have scannedin 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.



#56
Sep1405, 06:51 AM

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Zz. 


#57
Sep1405, 07:23 AM

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Lipa et al. references MS 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 MS. I'll go to the library today and get the KM papers; if they are as thorough as MS, then I'll be happy to start using them in their place. 


#58
Sep1405, 04:58 PM

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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. 


#59
Sep1405, 05:22 PM

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It is not likely that there are other than a few typographical errors in MS. This is what Kostelecky & Mewes, Phys. Rev. D, 66, 0560054 (2002) have to say about MS: "In this simple example, the transformation [tex]T^\mu_\nu[/tex] leaves invariant the rods and clocks, while [tex]\Lambda^\mu_\nu[/tex] leaves invariant the speed of light. Both are equally valid. In the frames related by [tex]T^\mu_\nu[/tex], 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 [tex]T^\mu_\nu[/tex], [tex]\Lambda^\mu_\nu[/tex], and their inverses." 


#60
Sep1505, 08:09 PM

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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. 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 eastwest and westeast 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, travelling 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 eastwest and westeast 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 nonisotropic 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). 


#61
Sep1605, 12:08 AM

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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. obserc = c + v. Of course we know that they got a null result. No one could believe it. The greatest minds could not accept this. Lets 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 


#62
Sep1605, 02:48 AM

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#63
Sep1605, 05:01 AM

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(33 MB) Mansouri & Sexl 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 nonsimultaneity Regards, Hans. 


#64
Sep1605, 05:26 AM

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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 [itex]c^2/v [/itex] ) 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 nonsimultaneity of time. Regards, Hans 


#65
Sep1605, 06:44 AM

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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 MansouriSexl and puts their work into a wider context. 


#66
Sep1605, 06:49 AM

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#67
Sep1605, 08:13 AM

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


#68
Sep1605, 09:36 AM

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



#69
Sep1605, 11:08 AM

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#70
Sep1605, 11:30 AM

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#71
Sep1605, 11:47 AM

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the single statement that "A wavefront is always at right angles with the direction of the wave in all reference frames." (This beauty already laid unrecognized in the M&M experiment) The example I use here (with the Broglie wave functions) works at any speed let is be at meters per second or centimeters per second. Regards, Hans 


#72
Sep1605, 11:53 AM

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