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The Gravitational Constant

  1. Oct 7, 2013 #1

    I am vexed by the Gravitational constant G.

    I have always thought that the gravitational force is proportional to mass and inversely proportional to distance^2, but it seems that it cannot be as cut-and-dry as this if we need to scale the relationship by G, with units of distance^3 / ( mass * time^2 ). My inner suspicions tell me that the gravitational force may be more subtlety related to electromagnetic/quantum activity, with the masses of the bodies involved as the true scaling factors...

    Apparently, G is numerically and dimensionally equal to planck_length^3 / ( planck_mass * planck_time^2 )... Therefore, G is intimately related to planck's constant h, which lies at the very heart of quantum theory. Does this bother anyone else???

    I suppose this is my question: is it possible that gravity is actually a byproduct of the electromagnetic force, and, because all the mass of celestial bodies consists of an equilibrium of charge, we can use mass as a direct scaling factor for the gravitational force?

    All bodies with a temperature above absolute zero give off thermal radiation, which is electromagnetic, in spherical wavefronts. Is it possible that gravity is not the curvature of spacetime, but some kind of net reaction/bias applied the electromagnetic properties of free space?

    Any thoughts and input would be greatly appreciated.
  2. jcsd
  3. Oct 7, 2013 #2


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    Staff: Mentor

    Well, when you consider that the planck length, mass, and time include ##G## in their definition, it's not so surprising that with a bit of algebra I can write G in terms of those quantities... and it doesn't show any intimate relationship between ##G## and ##h##.
  4. Oct 7, 2013 #3

    D H

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    In Newtonian mechanics, gravitational force is proportional to the product of the two masses that are attracting one another gravitational and is inversely proportional to the square of the distance between the objects: ##F\propto \frac {m_1m_2}{r^2}##. Writing this proportionality as an equality yields ##F = G \frac {m_1m_2}{r^2}##. The units of this constant of proportionality are trivially length3mass-1time-2.

    A strong word of warning: Read our rules. You haven't breached them yet, but you are *this* close to doing so, and this is not a minor breach.


    That G is equal to planck_length^3 / ( planck_mass * planck_time^2 ) is a tautology. It is implicit in how those Planck units, particularly Planck mass, are defined.

    There is nothing to discuss here. Thread closed.
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