General relativity with infinite speed of light?

[bcrowell]

"... which are logically incompatible with Galilean relativity. "

Let me recall: "This may be done by introducing an ether concept in a way also suggested by Trautman [23]."

I didn't say that there can be no theory of E&M in Galilean relativity. I just said that mersecske needed to specify what theory it was, and that it couldn't be Maxwell's equations. If it's an ether theory, that's fine.

 

[arkajad]

Well, then let me quote more:

"Newton-Cartan theory must be supplemented by the usual Lorentz-covariant electrodynamics instead of its corresponding Newtonian limit. This may be done by introducing an ether concept in a way also suggested by Trautman [23]."

That is there are Maxwell's equations and ether theory - both, working together in a tandem.

 

[bcrowell]

Well, then let me quote more:

"Newton-Cartan theory must be supplemented by the usual Lorentz-covariant electrodynamics instead of its corresponding Newtonian limit. This may be done by introducing an ether concept in a way also suggested by Trautman [23]."

That is there are Maxwell's equations and ether theory - both, working together in a tandem.

Since 1905, the standard interpretation of Maxwell's equations has been that they describe physics without an ether. It might be interesting to know what Trautman had in mind, but the Trautman paper is in an out of print book that can't be viewed through amazon or google books, so it appears that it would be difficult for us to have a discussion of it here, unless everyone involved in the discussion was willing to go to a university library and find the book.

 

[arkajad]

Well, if you are interested, you may like to read the review and some philosophically oriented discussion "http://philsci-archive.pitt.edu/archive/00001096/00/Rynasiewicz.doc" " .

 

[bcrowell]

Thanks, arkajad, for posting the link to the Rynasiewicz paper. That's very helpful. It includes a summary of the Trautman construction.

If I'm understanding Rynasiewicz correctly, then essentially the Trautman construction is an aether theory with no unification of E and B, it has E and B frame-invariant, it has a finite speed of propagation of light, and it has been falsified by experiments such as the Michelson-Morley experiment. Rynasiewicz claims that it correctly encapsulates pre-1905 ideas about electromagnetism. It has both a Galilean metric and a Minkowski metric hidden in it. Both of these metrics are flat, so it really doesn't address mechanics in the way that Newtonian mechanics or Newton-Cartan gravity does; in particular, it can't provide a description of mass (either gravitational or inertial). Since it's only a theory of electromagnetism, it doesn't include the ability to discuss clocks. (You can't build a clock out of photons.) Since there are no clocks, the theory seems not to address the question of whether the Galilean metric or the Minkowski metric is the one that gives the correct description of time, e.g., whether or not time dilation exists. To my mind, then, the theory's incompleteness means that it doesn't constitute a counterexample to my claim that the standard interpretation of Maxwell's equation is right: Maxwell's equations are incompatible with Galilean relativity. It seems to me that what Trautman, Earman, and Rynasiewicz are debating is not whether Maxwell's equations are incompatible with Galilean relativity. I think they're discussing something much more restrictive: whether or not there even exist interesting and historically relevant examples of physical theories in which space is absolute.

Would you disagree with any of the above in factual terms, or only in interpretation?

 

[atyy]

http://arxiv.org/abs/0904.0531

?

 

[arkajad]

I would say Trautman's was an attempt that had an effect of encouraging other people to research more. I wouln't say that the weaknesses of this particular attemp prove that Galilean General Relativity is incompatible with Maxwell's equations, even if Duval and Horvathy (in the paper quoted in the previous post ) include such a sentence ("Notice the absence of the displacement current in Ampere’s law: its presence would, clearly, break the Galilean symmetry (Maxwell’s equations are relativistic").. One could try to argue this way that real numbers are incompatible with imaginary numbers because 1 squared is 1 and i squared is -1. That being true, we still have complex numbers and they are being nice and useful. For Galilean-type general relativity there is a recent paperhttp://arxiv.org/abs/1003.5366" . No avenue of research has been definitively closed, all paths are open, experiment will decide which of the future theories will succeed.

 

[bcrowell]

Hi, Arkajad -

I think you're mixing apples and oranges here. The Trautman-Earman-Rynasiewicz is purely historical and philosphical, and is about theories that were falsified by observations a century ago. The Hikin paper has not been published in a peer-reviewed journal. Hikin does give references to two peer-reviewed papers by Jacobson and Mattingly: http://arxiv.org/abs/gr-qc/0007031 , http://arxiv.org/abs/0801.1547 . These papers are interesting, but they do *not* reconcile GR with Galilean relativity. They describe a theory in which Lorentz invariance is valid at low energies, but is broken at high energies. The theory has not been falsified by experiment, but observations place constraints on the parameters c₁ and c₃ that describe its disagreement with GR.

Please take a look at PF's rules on overly speculative posts: https://www.physicsforums.com/showthread.php?t=414380 "It is against our Posting Guidelines to discuss, in most of the PF forums or in blogs, new or non-mainstream theories or ideas that have not been published in professional peer-reviewed journals or are not part of current professional mainstream scientific discussion."

-Ben

 

[arkajad]

Please take a look at PF's rules on overly speculative posts: https://www.physicsforums.com/showthread.php?t=414380 "It is against our Posting Guidelines to discuss, in most of the PF forums or in blogs, new or non-mainstream theories or ideas that have not been published in professional peer-reviewed journals or are not part of current professional mainstream scientific discussion."

-Ben

Well, you can always kick me off, any time. It's up to you. I think that in physics occasionally mixing apples with oranges is healthy.