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Thread: Does the inverse square law eventually fail?

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    Does the inverse square law eventually fail?

    It seems to me if gravity is mediated by a quantum particle, i.e. a graviton, then at some appreciable distance the inverse square law would ultimately fail as the gravitons from the source would be too diffuse. At some very long distance there’s just a single graviton moving through a region of space and it’s not diffusing at all.

    Or am I missing something?

    SLD

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    Contributor repoman's Avatar
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    What about light?

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    Contributor barbos's Avatar
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    It's not how it works. Analogy you use is incorrect.
    As distance from the source increases virtual gravitons get progressively softer and softer but there are more and and more of them.
    Basically, inverse square law does not apply here.

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    It is easier to see with light.

    A theoretical isotropic radiator is an infintly small point radiating equaly in all directs. We treat distant stars as isotropic radiators.

    Imagine a spjere around the radiator in cresing in diameter. Ognorring any losses the total energy crossing the spere at and radius is constant, conservation of energy. For an 1 meter square aera on the surface of the expanding sphere energy density goes down by inverse square. I have measured it with optical sensors.

    As radius gets lathe a 1 square meter surface on the sphere appears flat. You can draw similar triangles and I believe derive 1/r^2 with a little trig. You can also look at the wiki page on solid angles.

    Energy is the capacity to do work. Light is modeled as photon particles as energy carriers and as a wave. Gravity is measured as a force resulting from accelerating a mass.

    It doesn't matter abut fields waves and particles. It is about energy density in joules however it is derived. If inverse square fails then energy has to show up somewhere.

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    Contributor barbos's Avatar
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    If photons had mass there would have been no inverse square law, as is the case of electro-weak field.
    There is also no inverse square law in strong force even though gluons have zero mass. (gluons have strong charge charge instead)
    Analogy does not apply to fields.

    It doesn't matter abut fields waves and particles. It is about energy density in joules however it is derived. If inverse square fails then energy has to show up somewhere.
    If it were true and this simple analogy were applicable then object would be constantly losing said energy due to "radiation" of said particles.
    Last edited by barbos; 02-04-2019 at 03:43 AM.

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    Ut IMO has nothing to do with mass. It is about how wedefine and measure energy.



    Imagine a small high density homogeneous mass.

    Regardless of how big a sphere around the mass the total gravitational potential energy integrated over the sphere remains constant. If not conservation of energy says an increase must come from somewhere and a decrease must go somewhere.


    A radio transmitter is radiating photons, the energy to radiate the photons comes from the power mains, the power station generates energy from coal, coal comes from.....ad infinitum.
    A star is always loosing energy. And we now switch to a debate on cosmology...

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    Contributor barbos's Avatar
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    You are confusing and conflating different things and simply wrong.

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    Quote Originally Posted by barbos View Post
    You are confusing and conflating different things and simply wrong.
    Another conservation of energy denier? The Earh has a finite amount of gravitational potential energy. If not the off we go into infinity la la land.


    Take a look at Potential Theory and Poisson's Equation. The equation shows up everywhere. It is not something I can jump into but all forms of static potential and dynamic forms of energy all take on the same mathematical form

    https://en.wikipedia.org/wiki/Potential_theory


    Looking at from Gauss's Divergence Theorem the total energy crossing the surface bounding a source is equal to the sum of the energy contained in sun of volumes as dxdydz goes to 0.

    Energy reduces to curl, divergence, gradient, Laplace and Poisson.

    We use all of it in engineering. Divergence theorem converts a surface integral of a closed surface to a summation of volumes within the surface.

    https://en.wikipedia.org/wiki/Divergence_theorem

    Any inverse-square law can instead be written in a Gauss's law-type form (with a differential and integral form, as described above). Two examples are Gauss's law (in electrostatics), which follows from the inverse-square Coulomb's law, and Gauss's law for gravity, which follows from the inverse-square Newton's law of universal gravitation. The derivation of the Gauss's law-type equation from the inverse-square formulation or vice versa is exactly the same in both cases; see either of those articles for details.[8]

    https://physics.stackexchange.com/qu...ral-relativity

    I'd say your overall problem is not understanding that regardless of theory or form energy reduces to a measure in SI units. It is not theoretical abstractions. The effect of energy is a measured force. Even in GR when you make a measuring it will be a force. It is inescapable. Unless you argue in GR you can get more or less gravitational energy from a mass...

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    Contributor barbos's Avatar
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    Dude, I have PhD in physics (particle physics)
    You are talking nonsense.

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    Yeah, I don't see why the Average amount of energy transmitted can't reduce ad infinitum. There's no limit to the amount an average can be divided to.

    I'm not a physicist, but one take away I had from learning about it is that when discussing very small quantities, all one can talk about is averages and probabilities. That's kind of what Heisenberg's Uncertainty Principle is about. And when we are talking such small quantities, we have to be talking in Quantum Physics, not General Relativity. The fact that the two don't translate well to each other has been well known for more than a century.

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