Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Cranks vs Einstein

  1. Feb 7, 2010 #1
    "Cranks" vs Einstein

    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
     
  2. jcsd
  3. Feb 7, 2010 #2

    HallsofIvy

    User Avatar
    Science Advisor

    Re: "Cranks" vs Einstein

    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.
     
  4. Feb 7, 2010 #3

    D H

    User Avatar
    Staff Emeritus
    Science Advisor

    Re: "Cranks" vs Einstein

    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.

    Exactly. What motivates the cranks is that if they prove Einstein wrong then they have proven themselves to be smarter than Einstein.
     
  5. Feb 7, 2010 #4
    Re: "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?
     
  6. Feb 7, 2010 #5

    atyy

    User Avatar
    Science Advisor

    Re: "Cranks" vs Einstein

    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?
     
  7. Feb 7, 2010 #6

    bcrowell

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Re: "Cranks" vs Einstein

    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.
     
  8. Feb 7, 2010 #7
    Re: "Cranks" vs Einstein

    Thank you, for that. it helps clarify my thoughts.
     
  9. Feb 7, 2010 #8
    Re: "Cranks" vs Einstein

    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?
     
  10. Feb 7, 2010 #9

    bcrowell

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Re: "Cranks" vs Einstein

    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...?
     
  11. Feb 7, 2010 #10
    Re: "Cranks" vs Einstein

    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?
     
  12. Feb 7, 2010 #11

    atyy

    User Avatar
    Science Advisor

    Re: "Cranks" vs Einstein

    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. "
     
  13. Feb 7, 2010 #12

    bcrowell

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Re: "Cranks" vs Einstein

    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.
     
  14. Feb 7, 2010 #13
    Re: "Cranks" vs Einstein

    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.
     
  15. Feb 7, 2010 #14
    Re: "Cranks" vs Einstein

    Aesthetics have no place in Physics; only metaphysics (aka capital 'I' Interpretations).
     
  16. Feb 7, 2010 #15

    bcrowell

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Re: "Cranks" vs Einstein

    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.
     
  17. Feb 7, 2010 #16
    Re: "Cranks" vs Einstein

    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.
     
  18. Feb 7, 2010 #17

    atyy

    User Avatar
    Science Advisor

    Re: "Cranks" vs Einstein

    http://books.google.com/books?id=4D...resnum=4&ved=0CBUQ6AEwAw#v=onepage&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)
     
  19. Feb 7, 2010 #18

    bcrowell

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Re: "Cranks" vs Einstein

    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.
     
  20. Feb 7, 2010 #19
    Re: "Cranks" vs Einstein

    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.
     
  21. Feb 7, 2010 #20

    atyy

    User Avatar
    Science Advisor

    Re: "Cranks" vs Einstein

    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.
     
  22. Feb 7, 2010 #21
    Re: "Cranks" vs Einstein

    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.
     
  23. Feb 7, 2010 #22

    atyy

    User Avatar
    Science Advisor

    Re: "Cranks" vs Einstein

    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?
     
  24. Feb 7, 2010 #23
    Re: "Cranks" vs Einstein

    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.
     
  25. Feb 7, 2010 #24
    Re: "Cranks" vs Einstein

    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.
     
  26. Feb 7, 2010 #25

    pervect

    User Avatar
    Staff Emeritus
    Science Advisor

    Re: "Cranks" vs Einstein

    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.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook