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Was Mach right after all?

  1. May 12, 2007 #1
    It is always convenient to raise something you don't quite understand to the status of a Principle. Mach's Principle seems to be a case in point; over the years it has greatly puzzled many Physicists and Philosophers. It certainly still puzzles me. Perhaps this forum can dispel some of my confusions.

    As I understand it, Mach's Principle (MP) seems to attribute inertial mass to a quite unknown species of integrated action-at-a-distance, originating from all the matter in the universe. Mixed up with this principle is the idea that the "fixed stars" provide a preferred frame of reference, against which acceleration and rotation can be gauged. From a modern perspective Mach might have preferred to replace Newton's reference frame of absolute space, long out of fashion, with a frame co-moving with the galaxy clusters of the Hubble flow. Such a frame would now be set in the context of General Relativity, (GR), although MP is not thought to be a consequence of GR. Nevertheless it has a "global' (as distinct from "local") flavour in the relativistic sense.

    General Relativity teaches that all inertial reference frames are equivalent. But from a local perspective it is now clear that there is one local inertial frame that can be picked out from the infinite number of such physically equivalent local frames. This is the frame at rest with respect to the Cosmic Microwave Background (CMB). From a local perspective this CMB frame restores Newton's absolute reference frame, but without imposing the restrictions of Galilean coordinate tranformations. From a global perspective there is no single (non co-moving) CMB frame. CMB frames, like the one we are coasting through at about 600 km/sec, are a local concept. Each locality, equipped with its infinite set of inertial frames, has its own unique local CMB frame that (in a model FRW universe) strictly follows the Hubble flow.

    George Orwell might have claimed that this inertial frames is more equal than the rest!

    I would like to ask: The CMB is thought to have been the photonic component of all mass/energy at decoupling; i.e. before gravitational condensation coagulated the universe. Could it, acting as a marker for all mass/ energy in the universe, somehow determine inertia and permit us to gauge acceleration and rotation? Or are we past such ideas?

    Is it possible that Mach was in a sense right after all?
     
  2. jcsd
  3. May 12, 2007 #2
    why do you think that mach was wrong?
    as far as i can tell mach's principle was an attempt to refute newton's bucket thought experiment, which he said that the concave shape of the water would occur even when the bucket and water are the only stuff in space.
    as far as i can tell, a solution to this question is still open.
     
  4. May 12, 2007 #3

    turbo

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    Einstein believed that Mach was wrong, and that inertial effects arise from matter's motion relative to the local vacuum (ether) in which it is embedded. He rejected "spooky action-at-a-distance" out-of-hand. There may be no definitive proof that Einstein was right, but I'd not want to bet against him in this matter. In his 1920 book on relativity, his 1920 acceptance speech at Leyden, and his 1924 essay "On the Ether", Einstein went to great pains to point out that GR was not a complete theory, and that it lacked a viable mechanism for the emergence of gravitational and inertial effects. His contemporaries were horrified because by elevating the local vacuum to this level of importance, he was re-establishing the concept of the ether. I believe that Einstein was right, and that current research into the fine-scale structure of space (LQG) may eventually bear him out.
     
  5. May 12, 2007 #4

    ZapperZ

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    But your statement here is horribly inaccurate. Einstein had ZERO concept of the vacuum state that we now deal with. In fact, considering that he was very much against the EPR-type interaction, he would have been horrified at the same type of vacuum interactions that is envisioned not only within LQG, but also in String, etc. This is NOT the same type of "ether" that Einstein had in mind, if it is at all. In fact, other than you and some other fringe articles, no one is calling such things as "ether", because it is utterly misleading.

    Zz.
     
  6. May 12, 2007 #5

    turbo

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    Einstein called the vacuum the ether in part because he required it's existence to support the transmission of light through space, and this was fundamental to his idea of gravitational lensing.

    http://www.bartleby.com/173/22.html

    Sometimes, people on the fringe are right, or at least are asking the right questions.
     
  7. May 12, 2007 #6

    ZapperZ

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    But often times, and more often than you can imagine, they go NOWHERE. Have you ever considered that? How many times, for example, have YOU contributed anything to physics that actually had an an impact? Based on that track record, how can you equate yourself with those who actually got it "right"?

    You STILL haven't argued any anything in LQG has any resemblance to what Einstein had in mind. Just because it hops on 2 legs does not automatically make it a rabbit. That is what you are trying to argue, and it make no logical sense.

    Zz.
     
  8. May 12, 2007 #7

    turbo

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    I have been collaborating with a researcher in Finland and another in New York for the past year and a half regarding a certain class of interacting galaxies. The first paper is in process. When the paper is accepted for publication, I will gladly link the preprint on this forum. That paper will present our catalog and raw data. The second and third papers (statistical analysis and interpretation) will likely have an impact.

    OK, Fotini Markopoulou has posited that light interacts with the vacuum through which it propagates, and she believes that Glast may demonstrate a frequency-dependent lag in arrival times of EM from Gamma-ray bursts, demonstrating that light interacts with the small-scale structure of space, which the LQG folks have called spin-foam. If Einstein were alive today, I believe that he would be very interested in the work of our friends at the Perimeter Institute. I'm surprised that you had not heard of this.
     
  9. May 13, 2007 #8

    Thanks for this comment. I just don't know whether Mach was right or wrong, but it seems that the answer to my OP question "... are we past such ideas? " is simply: NO.

    As for the "hanna-hanna" and "wurra-wurra" raised by ZapperZ about LQG's bearing on this matter.... since there seems to as yet be no answer to this kind of question, why not give new ideas a whirl, as Turbo-1 sensibly suggests:
     
    Last edited: May 13, 2007
  10. Sep 1, 2007 #9
    Newton used an absolute space in which his physical laws work - many philosophers rejected this idea. The famous bucket experiment was for Newton "the proof" for the existance of an absolute space - but Mach rejected and prooved that this is not a proof. If the absolute space would cause the shape of the water - then you must perform the experiment in an empty space to exclude the possibility that (motion relative to) other masses cause the shape of the water. Mach in general rejected the existance of an absolute space - it is meta-physical; positions and velocities with respect to an absolute space are not observableand therefore are meta-physical.
     
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