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Cranks vs Einstein

by exmarine
Tags: cranks, einstein
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Frame Dragger
#19
Feb7-10, 06:32 PM
P: 1,540
Quote Quote by bcrowell View Post
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.
Having an open mind AND principles which are imperfect in an imperfect world is who and what I am. I should say... Aesthetics should have no role in determining the nature of the theory, but rather nature should provide its own aethetic, intuitive or not.
atyy
#20
Feb7-10, 06:40 PM
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Quote Quote by bcrowell View Post
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.
I read your Amazon review, and agree with the technical point, and that this particular statement of Ohanian's is misleading. I concede that the tenor of this book is terribly annoying - unfortunately, I am in sympathy with much of it! Overall, I have found Ohanian's work (articles, textbooks and his latest annoying book) very helpful.

Anyway, I happen to like the modern form of Lorentz's viewpoint much better than Einstein's spacetime view (but I almost always calculate with Einstein's view!), and found it interesting that Lorentz himself stated the need for a unique ground state, which classical electrostatics does not have, but which Swann later pointed out is potentially provided by quantum mechanics. I have to ask - even till this day, do we know if Swann's argument has an explicit instantiation? After all, our theories of solid bodies are all non-relativistic, and are almost surely not any ground state of the standard model, which unlike classical special relativity, is not a consistent theory to arbitrarily high energies.
meopemuk
#21
Feb7-10, 06:42 PM
P: 1,746
Quote Quote by madhatter106 View Post
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.
There is huge logical gap between Einstein's thought experiments (which justify the use of Lorentz transforms for "light pulses", "light clocks" and similar model systems) and the idea of universal and all-encompassing space-time. The unified space-time idea can be valid only if one can prove that Lorentz transforms are applicable to all physical systems without exceptions. Special relativity does not prove this statement, but accepts it in an act of faith.

There is another approach, which is more logical in my opinion. It is based on well-known postulates of Poincare symmetry and quantum mechanics. No extra assumptions are made. The main idea is contained in

E. P. Wigner, "On unitary representations of the inhomogeneous Lorentz group", Ann. Math., 40 (1939), 149.

Applications to interacting systems are in

P. A. M. Dirac, "Forms of relativistic dynamics", Rev. Mod. Phys., 21 (1949), 392.

In this approach, there is no need to make any assumption about transformation laws of physical observables. These laws follow automatically from the dynamical description of any given system. It appears that in the presence of interactions positions of particles (or events) do not transform by usual linear Lorentz formulas:

E. V. Stefanovich, "Is Minkowski space-time compatible with quantum mechanics?", Found. Phys., 32 (2002), 673.

Eugene.
atyy
#22
Feb7-10, 07:27 PM
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P: 8,655
Quote Quote by meopemuk View Post
E. V. Stefanovich, "Is Minkowski space-time compatible with quantum mechanics?", Found. Phys., 32 (2002), 673.
I still haven't read your paper carefully, but have thought of more questions to ask (or maybe forgot that I asked them already). How does what you propose differ from relativistic quantum mechanics, which in textbooks is usually said to be ok as long as there is no particle creation, in which case one must use quantum field theory?
meopemuk
#23
Feb7-10, 08:03 PM
P: 1,746
Quote Quote by atyy View Post
I still haven't read your paper carefully, but have thought of more questions to ask (or maybe forgot that I asked them already). How does what you propose differ from relativistic quantum mechanics, which in textbooks is usually said to be ok as long as there is no particle creation, in which case one must use quantum field theory?
The answer is partly covered in the paper (a more detailed discussion can be found in http://www.arxiv.org/abs/physics/0504062). There is no antagonism between relativistic QM and QFT. This becomes obvious in the so-called "dressed particle" (or "clothed particle") representation of QFT. The relativistic QM is just a limit of the "dressed particle" QFT when particle energies are too low to change the number of particles. At higher energies interaction terms describing particle emission/creation become more and more important. But this does not change the general conclusion about the non-trivial interaction-dependence of boost transformations of particle observables.

This issue becomes very obscure in textbook (non-dressed) presentations of QFT. Because in the traditional approach, QFT can be used only to obtain scattering amplitudes. So, the time evolution of particle observables and their boost transformations is simply not available.

Eugene.
madhatter106
#24
Feb7-10, 08:27 PM
P: 140
Quote Quote by meopemuk View Post
There is huge logical gap between Einstein's thought experiments (which justify the use of Lorentz transforms for "light pulses", "light clocks" and similar model systems) and the idea of universal and all-encompassing space-time. The unified space-time idea can be valid only if one can prove that Lorentz transforms are applicable to all physical systems without exceptions. Special relativity does not prove this statement, but accepts it in an act of faith.

There is another approach, which is more logical in my opinion. It is based on well-known postulates of Poincare symmetry and quantum mechanics. No extra assumptions are made. The main idea is contained in

E. P. Wigner, "On unitary representations of the inhomogeneous Lorentz group", Ann. Math., 40 (1939), 149.

Applications to interacting systems are in

P. A. M. Dirac, "Forms of relativistic dynamics", Rev. Mod. Phys., 21 (1949), 392.

In this approach, there is no need to make any assumption about transformation laws of physical observables. These laws follow automatically from the dynamical description of any given system. It appears that in the presence of interactions positions of particles (or events) do not transform by usual linear Lorentz formulas:

E. V. Stefanovich, "Is Minkowski space-time compatible with quantum mechanics?", Found. Phys., 32 (2002), 673.

Eugene.
I'll go and read those, thank you.

In regards to the thought experiments they I'll say for me it tended to distract from the unified space time. I don't have an educated background in physics, or math beyond geometry. I was able to see at least to me the unification of space time when I dispensed with the clocks and such and by taking a view that removing time in the picture since it was already a function of the velocity and distance against the limit set by c. the light went off (bad pun). I think and hopefully I'm not far off, that time is just as arbitrary as distance since it's defined by the ratio of your velocity to c. for each frame of reference the measurement of time and distance is set by that ratio. and I arrive at that from the view of space time as the velocity of c. I don't know how to explain the construct I see in my head. I'm going to work on the units and math to see if I can find problems with my view.

Thankfully I do understand Cartesian coordinates as I've been doing 3-d computer modeling and animation for 20yrs.
pervect
#25
Feb7-10, 09:08 PM
Emeritus
Sci Advisor
P: 7,633
I'm not sure why the title contains the word "crank"? The title is rather unfortunate, fortunately the thread doesn't seem to be about what the title claims.

Anyway, my general view is that energy and momentum are core physical concepts, but the concept of "mass" is less well defined, particularly as it applies to GR. Many discussions would be better off if the word were avoided and the focus kept on what was well defined.

See for instance http://adsabs.harvard.edu/abs/2006PhTea..44...40H

The problem in my opinion isn't really that "There is no good concept of mass", as the above article purports, the problem is "There are too many good concepts of mass". For example, in GR we have Komar, Bondi, and ADM masses as the "top three", along with an uncertain number of other proposals.
Frame Dragger
#26
Feb8-10, 05:17 AM
P: 1,540
Quote Quote by pervect View Post
I'm not sure why the title contains the word "crank"? The title is rather unfortunate, fortunately the thread doesn't seem to be about what the title claims.

Anyway, my general view is that energy and momentum are core physical concepts, but the concept of "mass" is less well defined, particularly as it applies to GR. Many discussions would be better off if the word were avoided and the focus kept on what was well defined.

See for instance http://adsabs.harvard.edu/abs/2006PhTea..44...40H

The problem in my opinion isn't really that "There is no good concept of mass", as the above article purports, the problem is "There are too many good concepts of mass". For example, in GR we have Komar, Bondi, and ADM masses as the "top three", along with an uncertain number of other proposals.
That's a fine point. It was a terrible roadblock for me (as a non-physicist) to begin to understand the nature of massive bodies (in the context of cosmology 'massive'). Until I started to study Kerr BHs and their Komar Mass it was too abstract.

The problem of 'what is mass' is open to experiment and discussion, as well as being a question that is clear to anyone. How to figure out which description of mass is more than a fun model is... painfully hard.
heldervelez
#27
Feb8-10, 08:04 PM
P: 253
Quote Quote by Frame Dragger View Post
That's a fine point. ...
The problem of 'what is mass' is open to experiment and discussion, as well as being a question that is clear to anyone. How to figure out which description of mass is more than a fun model is... painfully hard.
I am convinced that 'standard model' and others accepted views, do not have any calculation of masses of fundamental particles by model, and they are just parametrers postulated by experimental values. I think that our unability to model mass, in a theory of particles, is a strong handicap and suspicious of the validity of the model.
I found a recent book (+-2000/2002) with a monograph of a candidate model of particles were masses are derived from first principles, on top of electromagnetism. Because I can not find any review, any reference or criticism, we can easily assume that the model is 'crank'. But now I have a clear representation, a concept, and some equations of what is 'mass' . The model also made predictions on the masses of new particles, that are distinct of the known predictions. The author is a retired electronic engineer with a career dedicated to light.
dr_k
#28
Feb9-10, 09:39 PM
P: 69
Quote Quote by atyy View Post
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, 141–148 (2004)
Thanks for bringing this article to my attention -- it’s a fascinating read. Ohanian, perhaps, does appear a little “demonstrative” at times, but he delivers a plethora of historical information. Although Einstein didn’t deliver a precise proof, the depth of his physical intuition drove him to the correct conclusion. I was unaware of Laue’s contribution, and this paper rightfully acknowledges his significant contribution.

Although, I haven’t read Ohanian’s recent text, “Einstein’s Mistakes”. If it's an aggressive polemic, that would be unfortunate.


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