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Virtual photons and electron orbitals

  1. Sep 4, 2010 #1
    hi,

    when an electron stays in the same electronic orbitals with principal quantum number n, with a constant energy and momentum, are there still virtuals photons that are permanently exchanged between this electron and the nucleus?

    I believe that the electromagnetic field is equivalent with virtual photons. So since the electromagnetic field is always constant and permanent, there should be permanently virtual photons that are exchanged. Am I right?
     
  2. jcsd
  3. Sep 4, 2010 #2

    tom.stoer

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    Virtual photons are a mathematical construction appearing in the language of quantum field theory. Orbitals and quantum numbers of electrons are defined using the language of quantum mechanics; in quantum mechanics no virtial photons appear, the Coulomb potential is a non-quantized entity.

    In QED one can show how the Coulomb potential arises in the canonical approach of gauge fixing via unitary transformation (A°=0 gauge, quantization, gauge ficing of the residual gauge symmetry via implementation of the Gauss law constraint).

    In this formalism the Hilbert space is reduced to a physical subspace and the potential arises as something like a "frozen photon field", a relict of the unphysical polarizations of the photon. Therefore both Coulomb potential and virtual photons have the same origin but are rather artificial entities.

    In that picture there are virtual photons exchanged between the electron and the nucleus. The effects can be calculated and generate the so-called Lamb-shift, an tiny change of the energy levels of the electron induced by quantum fluctuations of the electromagnetiv field.

    http://en.wikipedia.org/wiki/Lamb_shift
     
  4. Sep 4, 2010 #3
    Call them photons, virtual photons, aetherites, or just thingies, it really doesn't matter. There exists a force carrier which allows the difference in charge to affect physical matter over distance, without direct contact. The negative electrostatic component of the electron is attracted to the positive electrostatic component of the proton - knowing exactly the mechanism by which this phenomena occurs may reveal deeper understanding, however, we are unable to determine exactly why and how it does what it does. We can only indirectly deduce the structure of atoms and form models to predict how matter will behave. To accurately understand the mechanism of how this occurs will require means of analyses which we do not possess. The result of this condition is the creation of yet another definition - call them photons or whatever, the effect isn't a thing at all - it is just a word that identifies the fact that something is happening within the distance between these two charged particles and creating an effect. Just because you assign a word to something does not mean it is fully understood - but strangely enough, it provides comfort to name it, so it is done and we all feel like we "get it", even though we haven't the faintest idea of why or how it does what it does.

    For example, I could say that the reason the electron stays in its orbit is because there is a string made of a material you cannot see or detect that is keeping it from flying away. QM is rooted deep in the imagination of man - so long as your explanation of why something does what it does matches what it does, you're in the clear.

    BTW: the electron stays in orbit because it likes the way the proton looks at it. ;)
     
    Last edited: Sep 4, 2010
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