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Speed of light depending on gravitational constant?

  1. Jun 10, 2015 #1
    I just wonder if there were any serious (and peer reviewed published, to be in line with guidelines) theory, which had proposed some link between speed of light in vacuum constant and between gravitational constant G. For example a calculation of speed of light based on G.
    Tried google search but with no result, so I guess the answer is no, but maybe somebody here will know better.

    Something similar to Maxwell approach calculating speed of light based on permittivity and permeability.
  2. jcsd
  3. Jun 10, 2015 #2


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    Staff: Mentor

    I don't think that concept would make sense at all. We use the speed of light to measure distances. How can the speed of light change in an objective way?
    Only dimensionless constants are fundamental, all other constants can get arbitrary values without changing physics by redefinition of our units.
  4. Jun 10, 2015 #3
    Under some circustances it would maybe make sense, but I cant write here about it, because it would be pure speculation, which would be agaist guidelines.
    But thanks for reply anyway, it seems that the answer is no, there is no such peer reviewed theory.
  5. Jun 10, 2015 #4


    Staff: Mentor

    There is no such theory, for the reason given. You can define your units of time and length to make c be anything you like, and your units of mass to do the same for G. You can even define funky units that change over time or across space to establish any relationship you like. There is simply no physical content to the idea.

    You may find this article helpful: http://math.ucr.edu/home/baez/constants.html
  6. Jun 11, 2015 #5
    Even if wikipedia is not a recommended source here, you may be interested by the recently reviewed article: "http://en.wikipedia.org/wiki/Variable_speed_of_light" which I think is addressing for a part your questioning.
    A by side interrogation seems to be: "With which speed does the gravitational interaction really move?" I know the theory and you can find professionally verified demonstrations proving that that speed theoretically is c, the same than the one of electromagnetic interactions (e.g.: Lichnerowicz, 1955). But on the other side of the reality you shall obviously discover that experiments confirming these theoretical demonstrations are, perhaps not missing, but rare and yet discussed. I hope it brings a positive and constructive contribution to your questioning.
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