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Cranks vs Einstein

by exmarine
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exmarine
#1
Feb7-10, 09:15 AM
P: 102
I see a lot of stuff on the internet from people that some would call "cranks", disputing SRT etc. (Personally, I try very hard to keep an open mind.) My question regards the fact that I have never yet seen any of those "cranks" directly discuss or dispute Einstein's thought "experiment" in his 05 paper, wherein two observers watch the same flash of light, both measure the same c, and that leads directly to the Lorentz transforms. Has anyone on these forums ever seen any attempt to dispute that experiment or derivation? It seems so elegant and straightforward to me. Are there any "weaknesses" in Einstein's argument?

Thanks,
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HallsofIvy
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Feb7-10, 09:37 AM
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Quote Quote by exmarine View Post
I see a lot of stuff on the internet from people that some would call "cranks", disputing SRT etc. (Personally, I try very hard to keep an open mind.) My question regards the fact that I have never yet seen any of those "cranks" directly discuss or dispute Einstein's thought "experiment" in his 05 paper, wherein two observers watch the same flash of light, both measure the same c, and that leads directly to the Lorentz transforms. Has anyone on these forums ever seen any attempt to dispute that experiment or derivation? It seems so elegant and straightforward to me. Are there any "weaknesses" in Einstein's argument?

Thanks,
BB
Are you sure YOU have understood that argument? You seem to be taking it as a given that "both measure the same c" and that the important part is "that leads directly to the Lorentz transforms". Both of those were well know prior to Einstein's paper- that's why they are called "Lorentz transforms" and not "Einstein transforms"! Lorentz developed them from the fact that speed of light is constant for all observers, which itself followed the basic laws of electro-magnetism.

Lorentz, at the time he developed those transforms, prior to Einstein's paper, presented a theory that motion caused the electomagnetic field solids, such as the arm of a device measuring the speed of light, to be stronger in the direction of motion which, in turn, caused the arm to "shrink" slightly (as given by his transforms) and so give a speed of light relative to any observer the same, as opposed, say, to a baseball thrown toward a moving person.

Einstein argued instead, that the space itself, between objects, would contract in the same way- and, so, in fact, would time. Further experimentation showed that Einstein's theory, not Lorentz's theory, was correct.

In any case, what the cranks ignore, and the only thing that determines the truth of a physical theory is not "thought experiments" but the actual physics experiments. And relativity has done amazingly well with them.
D H
#3
Feb7-10, 10:14 AM
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Quote Quote by HallsofIvy View Post
Further experimentation showed that Einstein's theory, not Lorentz's theory, was correct.
If by Einstein's theory you mean special relativity, that statement isn't correct. Lorentz ether theory and special relativity are indistinguishable in terms of predicted outcome. They differ in their axioms, not their outcomes. The Lorentz transformation is axiomatic in Lorentz ether theory but is a derived result in special relativity. What further experimentation showed is that special relativity (and hence Lorentz ether theory) is not a universal truth. The theory that does a better job of explaining reality is general relativity. Special relativity falls out as a special case of general relativity.

The reason physicists vastly prefer special relativity over Lorentz ether theory is that the axioms of special relativity are testable and are much more basic and much less ad hoc than those of Lorentz ether theory. In addition to postulating the Lorentz transformation (where the heck does this come from?), Lorentz ether theory postulates an absolute reference frame that is inherently unobservable. Above all else, physicists want their theories to have testable axioms. This unobservable absolute reference frame in Lorentz ether theory is not testable; it is metaphysics rather than physics.

In any case, what the cranks ignore, and the only thing that determines the truth of a physical theory is not "thought experiments" but the actual physics experiments. And relativity has done amazingly well with them.
Exactly. What motivates the cranks is that if they prove Einstein wrong then they have proven themselves to be smarter than Einstein.

exmarine
#4
Feb7-10, 01:47 PM
P: 102
Cranks vs Einstein

Jeese, that's the trouble with these forums - one gets "answers" like that one from "HallofIvy". Please go re-read the question sir.

(1). They both measure the same value for c. As far as I can tell, that's an objective reality of our universe. Any problem with that?
(2). Space appears to be homogeneous. Thus the transforms must be linear. Any problem with that?
(3). And space certainly appears to be isotropic. Any difficulty with that argument?
atyy
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Feb7-10, 02:42 PM
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Quote Quote by exmarine View Post
Jeese, that's the trouble with these forums - one gets "answers" like that one from "HallofIvy". Please go re-read the question sir.

(1). They both measure the same value for c. As far as I can tell, that's an objective reality of our universe. Any problem with that?
(2). Space appears to be homogeneous. Thus the transforms must be linear. Any problem with that?
(3). And space certainly appears to be isotropic. Any difficulty with that argument?
Are you asking about flaws in the logic given the assumptions of homogeneity and isoptropy, or are you asking whether the assumptions themselves are flawed?
bcrowell
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Feb7-10, 02:49 PM
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Seems to me that both Hallsofivy and exmarine could de-escalate their language, and that would help in having an interesting discussion here.

Historically, Einstein did not know about Lorentz's work before he wrote the 1905 paper (source: Sommerfeld's footnote in The Principle of Relativity), so he also didn't know Lorentz's interpretation of the the transformation. He did know about the Michelson-Morley experiment ( arxiv.org/abs/0908.1545 ), but it probably didn't influence him that much, since he was already convinced that there was no aether lurking behind Maxwell's equations. In the 1905 paper, Einstein refers to the fact that experiments had failed to find aether-wind effects of lowest order in v/c. E.g., there was no effect to order v/c (Fresnel) or v2/c2 (Michelson-Morley). He uses this as motivation to discard the aether hypothesis completely. It's interesting to imagine how he would have originally presented his ideas if he'd been aware of Lorentz's work, but we just don't know.

Re DH's #3, I suspect that you're greatly overstating the case for Lorentz's ideas as a viable theory. Just being able to write down the Lorentz transformations is a completely different thing from coming up with the right outlines of a physical theory, which is what Einstein did. Lorentz didn't make a physical theory. Einstein did. We could try to imagine what would have happened if Lorentz had tried to go on with his approach. I really can't imagine, for example, that he could make up an aether theory that would explain things like Compton scattering and the perihelion precession of Mercury.

Re exmarine's #4, there are a couple of things I would say:

(a) Einstein's reasoning is very compelling *if* you're willing to give up absolute time. If you're not, then all you end up proving is that Einstein's postulates are incompatible with absolute time, and therefore you don't believe Einstein's postulates.

(b) Anti-relativity cranks are like anti-evolution cranks. They don't have a coherent set of ideas of their own. That makes it kind of pointless to debate them.
madhatter106
#7
Feb7-10, 03:00 PM
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Quote Quote by bcrowell View Post
.......
(a) Einstein's reasoning is very compelling *if* you're willing to give up absolute time. If you're not, then all you end up proving is that Einstein's postulates are incompatible with absolute time, and therefore you don't believe Einstein's postulates......
Thank you, for that. it helps clarify my thoughts.
exmarine
#8
Feb7-10, 03:48 PM
P: 102
Yes, thank you bcrowell. Your answer is helpful. The one exception to your point (b) that I know of would be Tom Phipps. He certainly has a coherent alternate. But my problem (one at least) with him is that I have never seen where he gives a specific critique of Einstein's derivation. And that's the motivation for my original question - are there any "weaknesses" in Einstein's assumptions, logic, or whatever. What could legitimate critics like Phipps be thinking?
bcrowell
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Feb7-10, 04:00 PM
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Quote Quote by exmarine View Post
The one exception to your point (b) that I know of would be Tom Phipps. He certainly has a coherent alternate.
There are various viable alternatives to standard relativity, e.g., Brans-Dicke gravity or Oestvang's quasi-metric relativity. If Phipps has a theory that is an interesting and viable alternative, presumably he's published it in a refereed journal...?
Frame Dragger
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Feb7-10, 04:32 PM
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Quote Quote by bcrowell View Post
There are various viable alternatives to standard relativity, e.g., Brans-Dicke gravity or Oestvang's quasi-metric relativity. If Phipps has a theory that is an interesting and viable alternative, presumably he's published it in a refereed journal...?
The problem with alternatives to Relativity is that it has some verification. Any theory competing to distinguish itself from Einstein would need to be proveable/falsifiable... and they rarely are.

The same issue comes up in QM, between SQM and dBB. Two explanations for the same basic notion, where one is dominant, but the other is still not 'crank'.

I thnk an easy way to sniff cranks is to see what they're selling (literally or intellectually). What is it that their theory allows or disallows that Relativity doesn't? Have they designed a theory to describe reality in a new way, or just modified SR/GR to suit their purposes?
atyy
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Feb7-10, 04:36 PM
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http://www.phys.uu.nl/~thooft/theoristbad.html
"Here is how to become a bad theorist: Compare yourself with Isaac Newton, Albert Einstein, Paul Dirac, or other celebrities in theoretical physics, and reach a conclusion in favor of yourself. Note that good theoreticians do not consider these famous physicists as saints; none of them were infallible, but the few instances where they could be corrected are well-known by historians of science, and do not have any effect on modern physics. "
bcrowell
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Feb7-10, 04:56 PM
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Quote Quote by Frame Dragger View Post
The problem with alternatives to Relativity is that it has some verification. Any theory competing to distinguish itself from Einstein would need to be proveable/falsifiable... and they rarely are.
Brans-Dicke gravity predicts deviations from GR in solar system tests. Such tests have forced BD gravity's coupling constant [itex]\omega[/itex] to be greater than 4x104, which means that the theory, while still technically viable, is not very interesting anymore.

Oestvang's QMR is consistent with all the standard tests of relativity, and makes predictions about the Pioneer anomaly that appear to be more consistent with observation than standard GR.

I don't think it works if you just apply a single criterion like falsifiability, consistency with experiment, ... On the criterion of consistency with experiment, Einstein's 1905 paper on the photoelectric effect should never have been published; it wasn't consistent with the experiments that had proved the wave nature of light. On the criterion of falsifiability, no paper on string theory should ever be accepted by a refereed journal. If we were going strictly by consistency with experiment, we'd all believe in QMR rather than standard GR.

Realistically, physicists make judgments based on a variety of factors. Among these are falsifiability, consistency with experiment, and aesthetics. When they judge consistency with experiment, they take into account how much they believe the experiment. In 1904, I don't think there was a clear consensus among physicists that the Michelson-Morley experiment meant what modern textbooks claim it obviously meant. Currently, I don't think there is a clear consensus on whether the Pioneer anomaly is real gravitational physics or just some boring effect we don't understand involving a spacecraft we don't have hands-on access to.

Re "they rarely are," I think the question is whether "rarely" refers to the set of all theories published in refereed journals, the set of all vague ideas hatched by college freshman, or some other set of theories.
meopemuk
#13
Feb7-10, 04:58 PM
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Quote Quote by exmarine View Post
I see a lot of stuff on the internet from people that some would call "cranks", disputing SRT etc. (Personally, I try very hard to keep an open mind.) My question regards the fact that I have never yet seen any of those "cranks" directly discuss or dispute Einstein's thought "experiment" in his 05 paper, wherein two observers watch the same flash of light, both measure the same c, and that leads directly to the Lorentz transforms. Has anyone on these forums ever seen any attempt to dispute that experiment or derivation? It seems so elegant and straightforward to me. Are there any "weaknesses" in Einstein's argument?

Thanks,
BB
Einstein's arguments and thought experiments are fine. However, they still have a serious logical "weakness".

These arguments involve simple non-interacting systems, like "flashes of light". So, Einstein's conclusions (e.g., Lorentz transforms) apply to such simple physical systems without doubt. However, it is more difficult to justify the application of Lorentz transforms to systems with interactions, such as charged particles or decaying nuclei. Standard special relativity assumes without proof that all relations derived in thought experiments with "flashes of light" (time dilation, length contraction, etc.) can be immediately and exactly extended to all possible physical systems (I am not talking about gravity here). It is quite possible that events associated with "flashes of light" do transform by Lorentz formulas, but different interaction-dependent transfomation laws should be used for interacting systems.

Eugene.
Frame Dragger
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Feb7-10, 05:17 PM
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Quote Quote by bcrowell View Post
Brans-Dicke gravity predicts deviations from GR in solar system tests. Such tests have forced BD gravity's coupling constant [itex]\omega[/itex] to be greater than 4x104, which means that the theory, while still technically viable, is not very interesting anymore.

Oestvang's QMR is consistent with all the standard tests of relativity, and makes predictions about the Pioneer anomaly that appear to be more consistent with observation than standard GR.

I don't think it works if you just apply a single criterion like falsifiability, consistency with experiment, ... On the criterion of consistency with experiment, Einstein's 1905 paper on the photoelectric effect should never have been published; it wasn't consistent with the experiments that had proved the wave nature of light. On the criterion of falsifiability, no paper on string theory should ever be accepted by a refereed journal. If we were going strictly by consistency with experiment, we'd all believe in QMR rather than standard GR.

Realistically, physicists make judgments based on a variety of factors. Among these are falsifiability, consistency with experiment, and aesthetics. When they judge consistency with experiment, they take into account how much they believe the experiment. In 1904, I don't think there was a clear consensus among physicists that the Michelson-Morley experiment meant what modern textbooks claim it obviously meant. Currently, I don't think there is a clear consensus on whether the Pioneer anomaly is real gravitational physics or just some boring effect we don't understand involving a spacecraft we don't have hands-on access to.

Re "they rarely are," I think the question is whether "rarely" refers to the set of all theories published in refereed journals, the set of all vague ideas hatched by college freshman, or some other set of theories.
Aesthetics have no place in Physics; only metaphysics (aka capital 'I' Interpretations).
bcrowell
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Feb7-10, 05:34 PM
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Quote Quote by Frame Dragger View Post
Aesthetics have no place in Physics; only metaphysics (aka capital 'I' Interpretations).
The historical record shows very, very clearly that aesthetics have always had a huge place in the development of physics. E.g., Thomas Kuhn's The Structure of Scientific Revolutions lists historical criteria for choosing a theory that include simplicity, as in Occam's razor. This is an aesthetic criterion.

You may have a personal philosophy that discounts aesthetics, but then I wonder how you decide whether to be more interested in QMR or in GR. After all, QMR is consistent with all the experimental data, and GR isn't.
madhatter106
#16
Feb7-10, 05:35 PM
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Quote Quote by meopemuk View Post
Einstein's arguments and thought experiments are fine. However, they still have a serious logical "weakness".

These arguments involve simple non-interacting systems, like "flashes of light". So, Einstein's conclusions (e.g., Lorentz transforms) apply to such simple physical systems without doubt. However, it is more difficult to justify the application of Lorentz transforms to systems with interactions, such as charged particles or decaying nuclei. Standard special relativity assumes without proof that all relations derived in thought experiments with "flashes of light" (time dilation, length contraction, etc.) can be immediately and exactly extended to all possible physical systems (I am not talking about gravity here). It is quite possible that events associated with "flashes of light" do transform by Lorentz formulas, but different interaction-dependent transfomation laws should be used for interacting systems.

Eugene.
I wonder though if the light clocks and thought experiments were a way to try and explain the space time that Einstien had arrived at. it's not an intuitive system. then like a game of telephone the main objective gets lost and the hoped for analogy is turned around to try and find incongruities.
atyy
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Feb7-10, 05:52 PM
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http://books.google.com/books?id=4Du...age&q=&f=false

http://arxiv.org/abs/0805.1400

I believe Ohanian's criticisms of Einstein's logic are correct. However, it must be stressed that Ohanian does believe that special and general relativity are valid in their extremely large domains of validity.

Interestingly, I believe Ohanian in an earlier paper defends Einstein's use of Newtonian dynamics in the low velocity limit to define an inertial frame "The essential point of this paper is then that dynamics cannot be avoided in the discussion of synchronization; and that once dynamics is brought into the discussion, it unambiguously selects the standard synchronization as the only synchronization compatible with Newton's laws in an inertial reference frame." H. Ohanian, "The role of dynamics in the synchronization problem," Am. J. Phys. 72, 141148 (2004)
bcrowell
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Feb7-10, 06:03 PM
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Quote Quote by atyy View Post
I believe Ohanian's criticisms of Einstein's logic are correct. However, it must be stressed that Ohanian does believe that special and general relativity are valid in their extremely large domains of validity.
I'm very suspicious of anything Ohanian says. He says, "It was not until 1941 that the American physicist W.F.G. Swann revisited Lorentz's arguments in the context of relativistic quantum mechanics and showed that, indeed, the length contraction emerges from a quantum-theoretical calculation of the length of a solid body when the length of a moving solid body is compared with the length of a similar body at rest." But this turns out to be totally wrong. (I wrote a review on amazon explaining why.) His motivation seems to have been to find any mistake in Einstein's work that he possibly could, and he doesn't seem to have been too fussy about playing fast and loose with the truth in order to do it.

The Ohanian "Einstein's E = mc^2 mistakes" paper strikes me as silly and pointless. So what if Einstein made certain assumptions in deriving the result? It strikes me as utterly unimportant.

What I really appreciate about Einstein as a scientific writer is that he makes the science physically clear for his audience. He was a physicist, not a mathematician, and he wrote like a physicist, not a mathematician. Good for him.


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