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Official speculation as to constant c

  1. Jul 1, 2004 #1
    http://www.newscientist.com/news/news.jsp?id=ns99996092

    this shouldn't be too much of a suprise.
    No need for incredibly expensive equipment either.
    It is known that light travels slower in denser materials. 'Materials' can include space itself since space consists of quantum fluctuations. Different densitys of these quantum fluctuations may alter the speed of light through it. Since space is reckoned to be expanding then it may be that speed of light is increasing with time. I think loads of people have speculated this at physicforums over the years. At last the experts are listening to our ideas!
     
    Last edited: Jul 1, 2004
  2. jcsd
  3. Jul 1, 2004 #2

    DW

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    You would think so, but to the surprize of many, they don't.
     
  4. Jul 1, 2004 #3

    hellfire

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    I had raised a time ago a similar question in another thread here, which remained unanswered, or let's say, without a clear explanation for me.

    My question was about the Scharnhorst effect (modification of the speed of light inside a Casimir vacuum) and it's conflict with special relativity (whether the Minkowski metric needs modification).

    I got Scharnhorsts original paper, but the whole issue is beyond my knowledge. May be you could shortly explain something about it, DW.

    Regards.
     
  5. Jul 1, 2004 #4

    DW

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    It doesn't matter whether someones prediction that the virtually vacuum speed of light is not actually c would be in conflict with SR, though that would actually not be. His specualtions from that prediction that it could be used to produce faster then c spaceflight was what was in conflict with SR, not the pridiction itself. What matters is that the prediction that the vacuum speed of light is not c is in conflict with observation. As I said, to many's surprise quantum foam changing the speed of light does not happen. The speed of light is somehow uneffected by it. I don't know why that is, but that does mean that in Casimir regions, the speed of light is the same as in normal vacuum. In either case the speed of light then is indeed c, not less.
     
  6. Jul 2, 2004 #5

    hellfire

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    I am not sure whether you understood what I was trying to expose. Here is the paper by Scharnhorst:

    http://arxiv.org/abs/hep-th/9810221

    Although this has no inmediate relation with the thread here (I apologize if it is off topic), I think this is an interesting related topic.

    Regards.
     
  7. Jul 2, 2004 #6

    DW

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    Yes I understood it. Did you understand mine? I was already familiar with that paper and I am telling you what is relavent.

    In short, his paper is wrong.

    In detail:
    1. He thinks that the virtual vacuum speed of light of deep space is what the Lorentz invariant speed c is, but that the speed of light would vary from this in regions where space has an abnormal virtual particle density.
    2. He thinks that light in Casimir vacuum travels faster than the Lorentz invariant speed c.
    3. He thinks that this can be used to permit faster than c travel.
    On all three assertions he is wrong.
    1. If the speed of light did vary with the density of virtual particles in the quantum foam then the lorentz invariant speed c would be the perfect Casimir vacuum speed of light, not the speed of light in deep space which would be lower, but in fact observations indicate that the speed of light is uneffected by quantum foam.
    2. If assertion one was right then the correct assertion for two would be that c is the perfect Casimir vacuum speed of light, not that light travels faster than c in Casimir vacuum. In fact due to the quantum foam having no effect on the speed of light means that the Casimir effect has no impact on the speed of light at all anyway.
    3. Since 2 is wrong 3 does not follow.
     
    Last edited: Jul 2, 2004
  8. Jul 2, 2004 #7
    Very good DW. Do you have any links to good pages on which verify what you say? It's feels a bit cold just accepting what you say without reason.
     
  9. Jul 2, 2004 #8

    DW

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  10. Jul 2, 2004 #9

    hellfire

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    I was obviously not understanding what you meant. Thanks for elaborating.

    Regards.
     
  11. Jul 3, 2004 #10

    Chronos

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    gack, you are misguided. 'c' is the speed of light in a VACUUM. refraction has nothing to do with that... [refer to the maxwell equation for the effect of subluminal velocities on wave forms].

    Get rid of of classical thinking if you wish to join the 21st school of thought about the universe. Think outside of the 'box'... your cat will worship you forever... [unlike schroedinger's].
     
  12. Jul 4, 2004 #11
    A couple of observations. 1) It would seem that dimensional-less constants such as alpha would be more likely to be "CONSTANT" than those which carry units such as G and e. Being a ratio devoid of physical dimensional aspects, what aspect of the physical universe gets involved in the change.
    2) The articles implication that long term variation of c would undermine theories like relativity does not seem to be justified - for example, mc^2 with a different c at some other epoch would simply affect the conversion magnitude - but the relationship would none-the-less remain valid.
     
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