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Energy-> space time curvature

  1. Oct 15, 2004 #1
    Energy---> space time curvature

    In general energy---> space-time curvature
    Any sperimental evidence that electromagnetism--->space-time curvature?

    blue
     
    Last edited: Oct 15, 2004
  2. jcsd
  3. Oct 15, 2004 #2

    pervect

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    As I mentioned before, gold and aluminum have different amounts of electrostatic energy. I think the figures were .4% and .1% of the total mass of the atoms were due

    But we know from Eotovos experiments that both are affected by gravity in the same way.
     
  4. Oct 16, 2004 #3
    Thanks... but this looks like that electromagnetism doesn't generate space time curvature. I got it correctly?

    blue
     
  5. Oct 16, 2004 #4
    Electromagnetism does generate spacetime curvature, i think. Here's my reasoning:

    Light propagates a flucttuation in both the electric and magnetic fields. These fluctuations can be represented as the bosons called photons (just go with me here), and photons have momentum and energy, and do cause space time curvature.

    The point i'm making is that the electromagnetic field carries energy, and so should cause spacetime curvature, but only if it carries its own energy as in the case of light. If for example, we just have a stationary point charge, there is no curvature, because the electric field possess no energy of its own independsnt of a charge placed in it.

    note: I'm only speculating here.
     
  6. Oct 17, 2004 #5

    pervect

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    I'm not sure why you think that.

    It's been demonstrated very - vigorously - that nuclear binding energies affect the mass of atoms. A coherent treatment of energy requires that electronic binding energies be treated in the same way as nuclear binding energies, that they affect the mass of atoms.

    The way the treatment works is that a bound system has a lower mass than an unbound system.

    It can be seen from the figures quoted that the total electronic binding energies are not a negligible part of the mass of atoms (.1% and .4% for Al and Gold).

    [edit]
    Note that in normal chemical reactions, only the outer electrons are involved. The energies here are low, the effect on mass is small enough to be ignored. But when you add together ALL of the electronic energy, esp. for heavy elements, it's a lot larger, because the inner electrons are very strongly bound, and the contribution to total energy is no longer negligible.
    [end edit]

    There's some more data on the magnitude of electronic binding energies at

    http://xray.uu.se/hypertext/EBindEnergies.html

    but I haven't personally added up these numbers and computed E/c^2, I've been relying on my text (MTW's Gravitation) to be accurate about the total percentage of energy that's binding energy in these elments.

    Comparing elements with a different amount of differing binding energies (i.e. different amounts of electronic binding energy, differing amounts of nuclear binding energy) in an Eotovos type balance should determine if elements with different sorts of energy distributions act differently with respect to gravity, or whether only the total energy matters.

    This is actually a test of the equivalence principle.

    To date, it's been found that only the total energy counts, it doesn't matter how much of it is nuclear binding energy, chemical binding energy, etc.
     
    Last edited: Oct 17, 2004
  7. Oct 18, 2004 #6
    well, according to E=mc^2, energy is proportional to mass. so i guess it could bend spacetime but you would need a very high amount of energy because m = E/c^2. if this has been posted, sorry, i didnt read any of the other posts.
     
  8. Oct 21, 2004 #7
    Even in classical electrodyamics and EM field can have energy, momentum and stress. There is no need to invoke photons to arrive at this conclusion. From this it follows that the stress-energy-momentum tensor, Tuv, is non-zero and at evets for which it is non-zero there is a non-vanishing spacetime curvature.
    ...and therefore mass..
    There is energy in/associated with all electric and magnetic field fields, even when they are static fields. If one then changes their frame of referece to one moving with respect to the charges rest frame then in that frame the momentum density of the fields will not vanish.

    Pete
     
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