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Eugene Shubert
the new William Miller
Joined: 06 Apr 2002
Posts: 1006
Location: Richardson Texas
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 Posted: Fri Aug 01, 2003 7:15 am Post subject: VSL (Varying Speed of Light) Special Relativity |
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Joao Magueijo asserts in his book, “Faster Than the Speed of Light: The Story of a Scientific Speculation”, Perseus Publishing, 2003, that revisions to special relativity that do not contradict the relativity of motion are possible.
| Quote: | | IT’S DIFFICULT to sum up where VSL stands, as I finish this book, because it is still well within the maelstrom of scientific inquiry. VSL is now an umbrella for many different theories, all predicting, in one way or another, that the speed of light is not constant, and that revisions to special relativity are required. Some of these theories contradict the relativity of motion—for example, the model Andy and I first proposed—but others don’t. Some predict that the speed of light varies in space-time, such as my Lorentz-invariant VSL theory and Moffat’s theory.” (p. 256). |
Judging from the pages I’ve read I don’t believe Magueijo’s claim for a minute. I am fairly confident that I can refute it easily. All I need is for someone to exhibit a concrete example—an explicit transformation equation—expressing how space-time events transform in different “inertial” frames of reference, preserving the principle of relativity. Out of all you researchers, and from the vast collection of VSL papers, does anyone here know how to write down even one of these alleged transforms explicitly for the easy case of one spatial dimension? |
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Eugene Shubert
the new William Miller
Joined: 06 Apr 2002
Posts: 1006
Location: Richardson Texas
|
| Posted: Sun Aug 24, 2003 6:01 pm Post subject: Re: VSL (Varying Speed of Light) Special Relativity |
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| On the newsgroup sci.physics.research, Marc Millis wrote: | An indirectly related theme to the idea of VSL is something that is sometimes called the "Optical-Analogy." Within GR, there exists some "Euclidean" interpretations, one of which is the "optical analogy." In this interpretation, the gravitational field is represented as an optical medium with an effective index of refraction [7-9]. Although different from the more common Geometric interpretation, this interpretation has been shown to be consistent with physical observables, and transformation rules between these two perspectives have also been published [8]. Little attention is typically focused on this perspective because it does not predict any new effects that aren't already covered by the more common Geometric perspective of GR, and because it raises unanswered issues with coordinate systems choices.
I hope that this adds to your repertoire of knowledge rather than to your confusion. This particular approach is easier to visualize.
7. de Felice, "On the Gravitational Field Acting as an Optical Medium", in General Relativity and Gravitation, 2, 347-357, (1971). 8. Evans, J., Nandi, and Islam, "The Optical-Mechanical Analogy in General Relativity: Exact Newtonian Forms for the Equations of Motion of Particles and Photons", in General Relativity and Gravitation, 28, 413-439, (1996). 9. Nandi, Kamal and Islam, "On the optical-mechanical analogy in general relativity", in American Journal of Physics, Volume 63, No. 3 (March 1995)
Also, I welcome comments from the other readers to highlight the strengths and weaknesses of this perspective. In particular, does anyone know a reference that critiques these from the point of view of issues with coordinate systems choices?
Marc |
Marc,
I deeply appreciate your contribution. I realize that interpretations like the optical analogy and Fermat's principle are directly related to VSL. Up until now I was only familiar with my own mathematical wonderment and some interesting but unprofessional speculations that I've read on the Internet. I agree that the optical analogy is easier to visualize. Isn't "an effective index of refraction" just another way to say "gravitational potential as a VSL theory?"
If the interpretation you mentioned is in a large degree "consistent with physical observables" then I believe that all students of math and physics should study it carefully. We should have as many competing theories as possible if for no reason than to gauge the better ones. Didn't Einstein say "Physical theories should be made as simple as possible—but no simpler." I know that a healthy diet requires variety.
I can understand the offense of abandoning curvature for "Euclidean" interpretations but don't recent cosmological observations suggest that your proposal is a very reasonable direction in practical research? I look forward to reading the literature you cited and the expert responses to the points you have made. |
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Eugene Shubert
the new William Miller
Joined: 06 Apr 2002
Posts: 1006
Location: Richardson Texas
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| Posted: Mon Sep 08, 2003 12:52 pm Post subject: Re: VSL (Varying Speed of Light) Special Relativity |
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| On the newsgroup sci.physics.research, Big Bird wrote: |
| Eugene Shubert wrote: | | I can easily imagine all "inertial" frames of reference being equivalent in a space that is homogeneous and isotropic, abandoning the homogeneity of time requirement and allowing a variable speed of light. |
You can imagine that? I can't.
First off, it seems you'd be abandoning the concept of spacetime itself if you demand that space but not time be homogenous. Surely this seems to say that the two are independent concepts -- and how, then, could there be Lorentz-like transforms that link the two?
Then, of course, abandoning homogeneity of time means abandoning conservation of energy via Noether's theorem. Certainly conservation of energy has all the experimental backup I could imagine any physical principle to have.
Thirdly I'd be curious to hear just what it would mean to write something as fundamental as "F = dp/dt" for an inhomogeneous "t". Derivative with respect to what? Or how would the Hamiltonian of a free particle look like?
This is approximately where my teeth start hurting just thinking about this and hence the question how you manage to imagine these things... |
Big Bird,
I am delighted that you view VSL spacetime as such an unimaginable revision of relativity and physics as we know it that the likelihood of its existence seems truly miraculous. You wanting to see an obvious model of the seemingly impossible is understandable. The problem I'm having is that reputable physicists claim it exists yet no one seems able to illustrate a VSL relativity theory by writing down an explicit coordinate transformation in 1 spatial dimension with the required properties.
x' =f(x,t), t' =g(x,t). How difficult is that?
I have requested these explicit functions at the newsgroup sci.physics.relativity. All I received was the citation of numerous articles and a persistent, stubborn refusal to write a specific x' =f(x,t), t' =g(x,t).
See this post for example.
See the whole thread as a vivid illustration of scientific make-believe and reality avoidance.
So you understand my dilemma. Physicists pretend that the functions I've requested are buried in the VSL literature. I claim they're not there. I would be more inclined to reveal my concrete construction of VSL relativity, which preserves the relativity of motion, and perhaps write a paper on it, if even a few physicists would admit that an explicit solution to the problem (i.e., the transformation equations) is still unknown. |
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Eugene Shubert
the new William Miller
Joined: 06 Apr 2002
Posts: 1006
Location: Richardson Texas
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