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Lorentzian Relativity and VSL theory

Paul C. Anagnostopoulos

Nap, interrupted.
Paul C. Anagnostopoulos
Joined
Aug 3, 2001
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Can anyone give us an introduction to Lorentzian Relativity and Varying Speed of Light theory? What do you think about it? Has it got potential, or is it whacky?

~~ Paul
 
Lorentz proposed the equations for the Lorentz transformation (aka Lorentz contraction) before Einstein figured out how to derive them from the assumption of fixed c. These formulas were derived by requiring that Maxwell's equations be invariant under a change of coordinates.

The non-SR interpretation is that there's an absolute, fixed ether, but when you move relative to the ether you get a contraction effect which results in your length and time measurements getting messed up just right. Thus, the Michelson-Morley experiment got a null result because the length of each arm of the apparatus changed as it was rotated relative to its motion through the ether.

Now the transformation equations are the same ones that Einstein derived from the assumption that c is fixed in all frames. So the actual predictions are the same: the theories are effectively equivalent.

So, why prefer Einstein's interpretation to Lorentz's? There are, I believe, three reasons.

First, insisting that Maxwell's equations be invariant is a good idea, but introducing the Lorentz transformation on those grounds is a bit ad hoc. Insisting that there is an ether and/or an absolute frame of reference, but it isn't detectable because objects compress when they move relative to it is rather complicated and "just so" vs. simply assuming c is constant. So out comes Occam's Razor.

Second, I think Einstein's SR is conceptually more productive. It leads more naturally to GR than a theory based on Lorentz alone would have. Now, people who insist on the ether like GR even less than SR, so they probably wouldn't have a problem with this, and in comes the VSL theory instead of GR. But just classical electrodynamics by itself is simpler in the formalism of special relativity.

Third, and I think this is very important, we need to think about what the definition of time and distance intervals are. Intervals in time and space must be defined operationally - that is, distance is defined by mechanical comparison to some length standard or device like a ruler, or a certain number of wavelengths of a certain sort of light, or something like that. Time intervals are measured by comparisons to mechanical clocks. Einstein's interpretation takes more seriously the operational nature of measurement - in fact, Einstein's derivation of the Lorentz transformations are based on the operational nature of time and distance measurements. Defining an absolute frame and a distortion thereof treats distance and time intervals as things that have an abstract existance independent of the measuring process and then "fixes" measurement problems with a hack. It's not operational.

Now, I don't know so much about the relationship between GR and VSL. My understanding of VSL is that its based on the idea that warps in spacetime can be treated mathematically like a variation in index of refraction (the optical analogy) and VSL is based on that. This seems like a neat idea. Again, I believe the mathematics ends up being equivalent, so there's no falsifiable way to decide between them - they're just two different interpretations of the same theory and, operationally, all the wierdness that happens in one theory will be present in the other (like differences in clocks, etc).
 
To Zombified's excellent explanation, I'll just add: no luminiferous ether. Back when, the wave model of light was popular, and it was a natural idea to have an ether as the medium through which light traveled by analogy to mechanical waves. Now we have a much better model of light (QED), and that kind of thinking doesn't seem so natural. Furthermore, the ether has a couple of conceptual problems with it. By Occam's Razor, if we can get a good theory without assuming the ether, then we might as well go ahead and do so.

Every few years, somebody tries to resurrect the ether for various reasons, but there's no smoking gun.
 
Paul, do you have a particular reference to Variable Speed of Light Theory?

As far as I can tell, the 19th Century concept of the ether was abandoned more or less with Einstein's General Theory of Relativity, since the ether was assumed to be homogeneous and isotropic, whereas gravitational fields are not.
 
Now,now the changing constants with the quick grasp at VSL as a supporting example , is indeed a theorem wielded by the creationists as the their latest pseudo scientific "application" of some postulated mathematical abstract.

There are a few Physicists with citation who believe VSL may have indeed been possible in the first inflationary phase after BB.

Joao Magueijo, one of Tez's fellows at Imperial collage is a main proponent of it along with a quite a few others. Unfortunately he has morphed the idea into an existing plastic metric where "Special Zones" exist contemporaneously . This is in the context of Super-string Theory and Prima Fascia is no stranger then some of the other offerings of other string theorists.

Somtimes tho it may not be a good idea to change horses mid-stream.
 
Yeah I know zombie thread and all that, but I just watched Joao Magueijo's "Big Bang" where, after a fairly standard explanation of the BB, CBR etc, he spent a fair bit of time talking about the Horizon Problem and how cosmic inflation was an explanation, but it was without any evidence. He then went on to outline his VSL theory, which also seemed to me to be without any evidence and, to a complete layperson, raise more problems than it solved.

So just leaving aside how this theory could be used by creationists, what is the status of VSL theory today? I did a google search, but it led me to sites which did not elaborate on the theory, or to sites too technical for me.
 
lionking said:
Yeah I know zombie thread and all that, but I just watched Joao Magueijo's "Big Bang" where, after a fairly standard explanation of the BB, CBR etc, he spent a fair bit of time talking about the Horizon Problem and how cosmic inflation was an explanation, but it was without any evidence. He then went on to outline his VSL theory, which also seemed to me to be without any evidence and, to a complete layperson, raise more problems than it solved.
Click to expand...

There is tons of evidence for inflation. If he said there wasn't he was at best strongly distorting the facts and at worst out and out lying. As for VSL, there's very little if any substance to it. Magueijo made a series of silly mistakes early on which he amplified by refusing to admit them (and presenting himself to the media as the next Einstein). In the end only a few people ever worked on it and it's been mostly abandoned even by its adherents - but Magueijo keeps clinging to it, I suppose because it made him slightly famous.

I think it's best to think about it like this: the speed of light is constant by definition (literally - look up the official definitions of the meter and the second). One is perfectly justified in making that definition because the speed of light has dimensions (length over time). It means nothing to say a dimensionful constant like that is changing with time unless you've specified how your meter sticks and clocks are changing too (for example if all units change at exactly the same rate, nothing really changes at all).

The best way to do things is to fix the dimensions and then only talk about dimensionless ratios (i.e. the speed of light divided by the speed of gravity waves). If THOSE are changing with time you know something interesting is going on. But there is no evidence at all that the dimensionless would-be constants of nature are changing, and the experimental constraints are very strong. Moreover we have considerable theoretical leverage because we have a good idea how they should be changing if they are, and what quantum mechanics has to say about that, etc.

So my advice is: forget VSL, and take everything Magueijo tells you with a lot of salt :).
 
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Thanks sol. If he is so far off the mark, why does he get TV gigs like this? I can just see this theory being picked up by lay persons and creationists alike purely because of shows like this..
 
I remember mentioning this a long time ago, JJ said that the fine structure constant alpha would change if the speed of light changed and that it would effect the spectrum of known but distant objects.
 
lionking said:
Thanks sol. If he is so far off the mark, why does he get TV gigs like this? I can just see this theory being picked up by lay persons and creationists alike purely because of shows like this..
Click to expand...

That's a good question. I don't think there's a short answer, but mostly it boils down to the fact that media is drawn to change, something new, to rebels and rebellions - not to established fact, even when the established facts are totally unfamiliar to the audience. So when some pseudo crackpot manages to make a splash, the media swarms like flies on ****.

The recent Garrett Lisi idiocy is a perfect example.

Dancing David said:
I remember mentioning this a long time ago, JJ said that the fine structure constant alpha would change if the speed of light changed and that it would effect the spectrum of known but distant objects.
Click to expand...

That's true, and that's the correct way to think about it. The fine structure constant is one of the dimensionless ratios I was talking about (and the bounds on its time variation are incredibly strong).
 
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