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What if C varies

  1. Oct 23, 2008 #1
    So light has constant velocity..what if C varies as per galilean relativity..
    What will happen?
    Can't we explain something(experiments or observations) if that happens?
    Will there be any change in our normal life? since we use light to see...
    Can't we come to E=mc2?
    Any change in our view of universe?
     
  2. jcsd
  3. Oct 23, 2008 #2
    I'll speculate on some items...maybe a theoretically correct answer will be posted....

    If the speed of light were different early in the universe from present we might not see many effects, depending on the magnitude of the difference. I believe some suspect it might have varied in the distant past. There may be evidence the fine structure contant has varied ever so slightly.

    If "c" were currently varying to any observable degree, casuality would also vary...space and time might become unpredictable... we'd be even harder pressed to tell before and after if we did not know how fast the information was transmitted...uncertainty would seem to increase dramatically...much if not all would be more unpredictable....

    I think other constants would also vary ruining atomic stability...think about electrons interactions with nuclei...via electromagnetic fields...if the speed changed, the field would change and EMF forces would vary....I guess metals, for example, might become slightly unstable...weaker then stronger...rest energy mc^2 would also vary screwing up energy conservation in interactions....likely the universe would not exist if it were an observable magnitude....electricity might surge thru transmission lines...
     
  4. Oct 23, 2008 #3

    rbj

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    i would suggest that you ask yourself exactly what the meaning of a variation of a dimensionful constant would be. how would we measure such a variation? or even perceive it? ultimately, we measure only dimensionless quantities usually as the ratio of a dimensionful quantity relative to some standard or unit of the same dimension.

    check out Carlip: "Have physical constants changed with time?"

    and

    Duff: "Comment on time-variation of fundamental constants", hep-th/0208093 (2004)

    Duff, Okun, and Veneziano: "Trialogue on the number of fundamental constants", JHEP 203 23 (2002), physics/0110060
     
  5. Oct 23, 2008 #4
    "for all observers, c is constant"..so what if c is different for different observers..it didnt mean the value of c changes from past to future Or about dimensionless constants...i know for c,if we change the units, we will get different value..sorry for not being elaborative...
     
  6. Oct 23, 2008 #5

    atyy

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    If c is different for different observers, then special relativity would not be a good model of our world. I've heard that two instances where special relativity can be seen in "everyday" life are magnetic fields due to Lorentz contraction of charges moving in a wire, and the colour of gold.
     
  7. Oct 23, 2008 #6
    Care to expand?
     
  8. Oct 23, 2008 #7

    rbj

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    spidey, please ask yourself "how does one get a different value?" be very specific and careful about the answer. consider how we measure or perceive the quantitative value of any physical quantity. consider units, references, standards, and the definitions of such.
     
  9. Oct 23, 2008 #8

    atyy

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