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A little puzzled about superluminality

  1. Jul 4, 2013 #1
    Recently I read some main-stream journals reporting about superluminal transport of EM energy; they say that is a quantum effect. For example,

    Phys. Rev. A 75, 042105 (2007) [4 pages]
    "Theoretical evidence for the superluminality of evanescent modes"
    http://pra.aps.org/abstract/PRA/v75/i4/e042105

    Annalen der Physik, Volume 17, Issue 5, pages 319–325, May 2008
    "Superluminal propagation of evanescent modes as a quantum effect"
    http://onlinelibrary.wiley.com/doi/...ionid=71EA4DFAA213DD3DB158976C861E2690.d04t01

    If the EM energy propagates at faster-than-light speed, then the photon moves at faster-than-light speed because the photon is the carrier of energy. But in the quantum theory, they say there are no concepts about particle's location and velocity, but just probability, or energy eigen states. How to understand the results reported in the above papers?
     
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  3. Jul 4, 2013 #2

    ZapperZ

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    OK. If you have access to these papers, then you should also have access to the citation index. You could have done just one simple step further and look at such citation. You would have seen several rebuttals to these papers.

    For example, the Phys. Rev. A paper already has several rebuttals disputing its "theoretical evidence". Read, for example, H.G. Winful Phys. Rev. A 76, 057803 (2007).

    You also need to realize that "theoretical evidence" really does not have that much of a weight when it is trying to propose something new and has no experimental evidence. After all, the whole of String Theory is nothing but "theoretical evidence".

    Zz.
     
  4. Jul 4, 2013 #3
    Such experiments for testing EM energy velocity probably are extremely difficult. That is why there are still a lot of disputes about the constency of light speed so far. To tell the truth, I don't understand the details from both sides, and I just have some straightforward judgement based on fundamental principles, but I don't know if it is correct.

    Sometime it is hard to say if a theory is correct or not. For example, light particle theory, which first proposed by Newton (although quite different from Einstein's photon), particle-->wave--->photon--->both.
     
  5. Jul 4, 2013 #4

    ZapperZ

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    There are NO disputes if you base it on what we can experimental measure. As far as I'm concerned, that is the only thing that will determine the validity of anything. Beyond that, what you have are SPECULATIONS. Are there disputes on those speculations? Sure there are! But do not confused those disputes to what we understand right now.

    Besides, you should also heed what you wrote. If it is true that it is "sometime hard" to say if a theory is correct, then let's just wait till there ARE valid experimental evidence to support a theory one way or the other. And until there ARE experimental evidence to show otherwise, there are no superluminal energy transfer.

    Zz.
     
  6. Jul 4, 2013 #5

    mfb

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    The standard model does not allow superluminal energy or information transfer, and no experiment saw a deviation from that. I don't see how a theoretical paper could contribute anything surprising - you can propose thousands of new models with superluminal energy transfer (in violation of the current models of physics), but there is no indication that any of those models would be true.
     
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