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Theory of conduction of electrical energy not a quantum theory.

  1. Nov 1, 2003 #1
    When Maxwell showed that light was an electromagnetic wave it was necessary to identify some oscillator of atomic proportions to account for these waves. Henri Lorentz , considered that electrons which are normally held in an equilibrium position are capable of vibration when displaced under the influence of a restoring force. The bound electron was supposed to be the source of the electromagnetic waves of light when executing damped vibrations. It was also capable of absorbing light when the frequency of the vibration and of the light were in agreement. This was more than a hundred years ago , much before quantum mechanics was formulated , today the only difference is that the vibrations have been shifted to ions in the crystal lattice. Thus the theory of electrical conduction as it stands today is not a quantum based theory at all. This is reflected in the fact that fields in an electrical conductor still function on an action at a distance principle.
     
  2. jcsd
  3. Nov 3, 2003 #2

    turin

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    (1) I'm not up on the history of physics, but are you sure that the vibrations were supposed to be considered damped? Do you know what they considered to be the damping mechanism?

    (2) How did they explain the sharp resonance without QM?

    (3) How does action at a distance disagree with or exclude QM?
     
  4. Nov 3, 2003 #3
    (1)
    The bound electron was supposed to be the source of the electromagnetic waves of light when executing damped vibrations.

    (3)
    Thus the theory of electrical conduction as it stands today is not a quantum based theory at all. This is reflected in the fact that fields in an electrical conductor still function on an action at a distance principle.

    I am just quoting from sources as far as the first point goes , but presumably the damping occurs because the electron was bound to the atom and so was not free to move. As for the second point one of the fundamental aims of QM is to eliminate the action at a distance phenomenon posed by the existence of fields , in the electromagnetic field this is achieved by photons (i.e all interactions in the field are due to photons ) which is why there is a contradiction , according to present day QM , photons cannot be either emitted or absorbed by electrons in an electrical conductor.
     
  5. Nov 4, 2003 #4

    turin

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    (1) Damping has nothing to do with whether or not a particle is bound.

    (2) Are you sure about that? I thought that classical field theory and relativity had already accomplished this. I don't know really anything about QFT, though. Is that what you're talking about?

    (3) Photons in an electrical conductor are not bound to an atom, as I understand it. There is a layer in which the electrons move freely, as long as they stay close to the metal. As far as emitting photons, I still haven't gotten a satisfactory answer why an electron would do that at all anyway. Do you have an explanation why fermions emit bosons. I have a suspicion that it is to preserve some symmetry or something, but again, QFT is not my thing (yet).
     
  6. Nov 4, 2003 #5
    (1) Damping has nothing to do with whether or not a particle is bound.

    (2) Are you sure about that? I thought that classical field theory and relativity had already accomplished this.

    (3) Photons in an electrical conductor are not bound to an atom, as I understand it. There is a layer in which the electrons move freely, as long as they stay close to the metal. As far as emitting photons, I still haven't gotten a satisfactory answer why an electron would do that at all anyway.

    1) It depends in what sense you are using the term damping , in the sense that Lorentz had used the term it is obvious that he refers to a force which opposes the vibration or oscillation of the electron and so damps the oscillations . Today we know that it is not the electrons that vibrate but the atoms of the lattice . This vibration leads to infra-red radiation in the 1mm range.
    2) It is not necessary to go as far as the study of QFT to understand that this action at a distance phenomenon has still to be solved , if you look at the present explanation for the movement of electrical energy in a conductor this will become apparent.
    3) According to the present theories there are no photons in an electrical conductor. The reason why electrons emit photons as has been postulated by Planck and Einstein is that light is emitted in discrete quanta of energy. You might like to look at http://www.geocities.com/natureoflight to see a new theory on the nature of light and electromagnetic waves
     
  7. Nov 4, 2003 #6

    FZ+

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    Theory of all electromagnetic interactions, as it stands today, is QED (quantum electrodynamics).

    That, as the name suggests, most definitely is a quantum theory. This branch of QM has been worked out long ago, and is pretty much the most accurately tested law of physics to date. (And yes, it involves virtual photons as guage bosons that carry the force, which is nothing to do with photon emission with the photoelectric effect.)

    You seem to be about 100 years out of date.
     
    Last edited: Nov 4, 2003
  8. Nov 5, 2003 #7
    (And yes, it involves virtual photons as gauge bosons that carry the force, which is nothing to do with photon emission with the photoelectric effect.)

    I think that this is just the type of confusion that I expected when I posted this thread , when I refer to electrical conduction , I am not talking about the properties of electrical conductors , which as you point out is one of the best explained and substantiated theories in physics , nor , basically am I referring to electromagnetic radiation , which has also been substantially explained . I am referring to the manner in which electrical energy flows through a conductor. According to the Pauli Exclusion principle , free electrons in a conductor can neither emit nor absorb photons , so how does the electrical energy in an electrical conductor get from one point to another . Most theories speak of an electric field.
     
  9. Nov 5, 2003 #8

    chroot

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    What on Earth makes you think this? The Pauli exclusion principle is simply an expression of the fact that two fermions have zero amplitude to be in the same quantum state. It does not apply to photons, which are bosons. It also has nothing to do with the electrons in a metal, which have an essentially infinite number of quantum states available to them. The electrons in a metal are essentially a free electron gas, and free-free emission is perfectly allowed.

    - Warren
     
  10. Nov 5, 2003 #9
    The electrons in a metal are essentially a free electron gas, and free-free emission is perfectly allowed.

    Hi Warren , get real . This is what I have been trying to say all along , that electrical energy in an electrical conductor must be conducted by photons , in the light of what we know it seems the logical choice both as regards the speed and power with which electrical energy is delivered , yet it isn’t. See ProdQuanta,s posting on “Photon not the electron …….” in this forum to see the point I am trying to make. A typical argument is photons are the force carriers for EM, but they are chargeless so they certainly are not the charge carriers in an electric circuit. In a circuit the electrical energy is created by the movement of electrons and hence charge.
    How does one relate this statement with the fact that a 100V , 1 amp current flowing through a wire a metre long results in an electron drift velocity of approx 0.4 mm , which is about 300 billion times less than the speed of c , yet electrical energy in an electrical conductor is established at near the speed of c ……..
     
    Last edited: Nov 5, 2003
  11. Nov 5, 2003 #10

    chroot

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    Photons are not charged. Photons are the "implementation" of the field, if you want to think of it that way, but they do not carry charge. The net movement of electrons is what moves charge, and that is what we call electricity.
    You answered this question yourself -- the charges themselves move very slowly. On the other hand, the photons that communicate changes in the electric field propagate at nearly the speed of light (depending upon the dielectric constant of the material).

    - Warren
     
  12. Nov 5, 2003 #11
    The photons that communicate changes in the electric field propagate at nearly the speed of light (depending upon the dielectric constant of the material).

    What you say should be the accepted practise but it isn't. Note that it isn't myself that is saying this , it is the accepted belief that photons have nothing to do with electrical conduction . Believe it or not.
     
  13. Nov 5, 2003 #12

    chroot

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    Yes, actually, it is the accepted practice. The field propagates at or near c. Changes in the field are communicated by (virtual) photons. This is exactly what the electromagnetic field does in gauge theory -- it permits local gauge invariance of quantum-mechanical phase. Anyone who knows quantum mechanics will tell you that changes in the field are communicated by photons. This is a (non-controversial) part of the Standard Model.

    - Warren
     
  14. Nov 5, 2003 #13

    jcsd

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    Mcqueen have you evr heard of 'electrical interference,'? I'm sure that you have, well those are photons (albeit of a very long wavelength) that represnt oscialltions in the electroc field.
     
  15. Nov 6, 2003 #14
    Warren kindly read JCSD's post to get some idea of the way things are , or better still Prod Quantas original post which has been shifted to theory development. Further if the field in a conductor , as you state is carried by virtual electrons , forget it , their energy is to transient to convey energy within the time parameters etc., imposed on conduction of electrical energy in a conductor. It would have to be much faster than the speed of light super , super luminal in fact.
     
  16. Nov 6, 2003 #15

    jcsd

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    Thge filed in a conductor IS carried by virtual photons, a real photon only represents a change in the electromagnetic field.
     
  17. Nov 6, 2003 #16

    chroot

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    Sorry McQueen, alternative theories are only welcome in the Theory Development forum. Those us with working experience in the field have given you perfectly satisfactory answers in agreement with all experiments, which you summarily reject without reason. Off to Theory Development you go!

    - Warren
     
  18. Nov 6, 2003 #17
    Hey Chroot ! I didn't know that you were a PF super mentor. I was thinking that you would be shunted off to theory development. But Thanks anyway.
     
  19. Nov 6, 2003 #18

    russ_watters

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    And he's gotten polite too. Its a bit unnerving. A week ago he would have b!tch slapped you.
     
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