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Want Proof that Photons have EM Properties

  1. Aug 5, 2004 #1
    The Objective of this Thread is:
    *** To Determine whether or not any definitive experiment has been done that proves that light photons do or do not possess EM properties. ***

    The Question is:
    Have any experiments been done under UHV conditions where a beam of light has been passed between the poles of:

    (A) an extremely strong electric field
    (B) an extremely strong permanent static magnet field
    (C) an extremely strong electromagnetic field

    which caused the beam of light to be either deflected or changed in some manner?

    In this experiment, we EXCLUDE / DENY the use of any state of matter (gas, liquid, solid and plasma) because matter is made of particles that contain magnetic and electric fields that complicate the data.

    The beam of light can be any type (laser, pulse, continuous, resonant) or wavelength.
    The E, M or EM field can also be any type (pulse, static, resonant).
    There can be multiple or mixed beams and/or multiple or mixed fields.

    The objective is to see if light, by itself, can undergo a deflection or a change by interacting solely with an E, M or EM field that is man-made and is not buried inside some atomic structure.
  2. jcsd
  3. Aug 5, 2004 #2
    E and M fields act on charges, which light doesn't have.

    If a charge moves when light hits it, what do you think has made it move?
  4. Aug 5, 2004 #3
    It sounds like the charge might be "at rest" or is "trapped" in a set of resonant fields (with a feedback loop). I know of no conditions where a charge can truly be "at rest". And based on my understanding all charges are in constant motion. So, before I can answer, please tell me the environment around the charge.

    If, by chance, the charge is inside a moving stream of charges, then there is some force keeping them moving. By giving the energy of the photon to the charge, the charge then has a larger EM field which works against the surrounding environment that keeps the charges moving.
  5. Aug 5, 2004 #4
    Classical EM predicts that light is not affected by such fields by virtue of Lorentz force law. QED does predict that scattering between photons is possible (and has been observed), but I do not know offhand if a real photon can scatter off a virtual one, which is how the process would be represented. As photons are neutral, I don't think these fields can do any work on them; it only remains to deflect the beam perpendicular to its direction of motion. This is where I defer to a higher expertise.
  6. Aug 5, 2004 #5
    There's pretty good evidence in that light behaves in accord with Maxwell's Equations in Maxwells Electromagnetic Theory of Light. It's interesting reading Chapter 5, Fundamentals of Photonics, Saleh and Teich, 1991, published by Wiley Interscience.

    Any photon model claiming otherwise would have to explain the predicted and observed behavior of the electromagnetic photon model.

  7. Aug 5, 2004 #6
    I'm almost afraid to ask, but what photon model would you have in mind that's not the "electromagnetic photon model" ?
  8. Aug 5, 2004 #7
    Unless some theory I'm unware of allows it, I don't see how an intense field as you suggest should deflect a beam of light, whether it is EM or not. E and M fields need charges to manifest themselves, so charged matter cannot be denied if you're looking for an E field.

    Rest is not implied. I was thinking of a photodiode. When it absorbs light, charges have moved, because a current was generated. We know E fields also moves charges, so the natural conclusion is that light must be an E field. Many other experiments and theories corroborate with this conclusion.

    To zefram_c : Wave model exclusively, Newton's model, whatever Archemedes thought light was.
    Last edited by a moderator: Aug 5, 2004
  9. Aug 6, 2004 #8


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    While I'm pretty sure such experiments have been done, I personally don't recall having read of any.

    Why not do such yourself? The laser would cost only ~$10 (a laser pointer), the vaccuum equipment only a few $hundred, and a pretty strong permanent magnet about the same. A pulsed electric field should be easy to make, the discharge of a camera flash (plus some simple electronics) may do the trick. A home-made van der Graf generator would also be easy enough to build, as would a tesla coil.

    The light bench may be tricky, esp as you want to quite sure that your laser source is quite isolated from the E and M fields you'll be generating.

    Alternatively, why not ask a friend in a good uni (or commercial research) lab to help? You'd get a ~1 or 2 OOM improvement in many aspects (deflection detection, pulsed M field, laser frequencies and intensity; E field?)

    This would enable you to test domains that are at least to the limits of 19th century capabilities; spending $million may get you only another OOM or two improvement.

    Just the back of my very small envelope. :smile:
  10. Aug 6, 2004 #9


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    more difficult than I first thought - maybe impossible?


    It just occurred to me, if you're trying to be *sure* there is no 'matter' in the photon path, as it transitions the E or B field, you may be requiring something that's impossible.

    First, even with the best UHV equipment in the world, there will still be some atoms/molecules in your vaccuum chamber; how could you be sure those few weren't somehow making a difference?

    Second, unless you do the experiment deep underground, with equipment that's devoid of radionuclides, you can't exclude cosmic rays or alpha, beta (or decay product) particles passing through your chamber.

    Third, nothing you can do will stop neutrinos! And, there will be vast numbers in your test chamber, all the time.

    Fourth, suppose you somehow managed to address all three points above, and got some clean data; how would you respond to the challenge "what about dark matter in your equipment?"
  11. Aug 7, 2004 #10
    No, not impossible, but yes, there will be stray atoms and particles even in X-UHV. Neutrinos, if they really exist, are expected to have no charge and almost no mass, so they won't make that much noise. Cosmic rays could cause some degree of entanglement, but they are a rare event - a basement and some lead would help. Stray electrons will be present and also cause background noise due to their EM, but a hollow tube should help there. Alpha rays (Helium nuclei), beta rays (electrons) are easy to stop with the same tube-shaped barrier. Dark matter is still a figment of imagination, and if it is present, it might appear as a null due to its uniform disturbance of the medium (QF, ZPF or aether).

    As for doing the experiment (last msg) , yes, I want to and will when the opportunity arises, but I was hoping to have some reference data, even it it produced negative results. Currently I'm in the thinking mode, and was hoping to find our if there are any experiments that have already been tried.

    Any ideas on who might help do the actual work are welcome.

  12. Aug 9, 2004 #11


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    When I first read these words my jaw dropped! But then, if the EM nature of EM radiation is under suspicion, it makes perfect sense that all the experimental and observational results on neutrinos would cut no ice :wink:
    Wait a minute! If your intent is to be quite pure wrt EM, how would you answer someone who claimed that your results are, in fact, the result of (previously undetected) photon-neutrino interactions?
    I think you're confusing dark matter with dark energy; the former is pretty well established (e.g. what else could cause so much lensing?), the latter has less good data going for it.
  13. Aug 9, 2004 #12


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    zefram c is correct: light-light scattering is part and parcel of QED. In fact, there's no problem with virtual photons -- no more so than there is with a scattered electron emitting a virtual photon, which, in turn, transforms into a pair. Strictly speaking, the photon beam will interact with the matter producing the strong fields, but through the medium of the E&M field produced by the matter.

    But, if I recall correctly, the field strength required to scatter a light beam is off the charts -- the experiment is extremely difficult, if it is at all possible. I suggest a GOOGLE on "non-linear optics", which should lead you to more than you want to know.
    I'd look at quasars as well.

    Reilly Atkinson
  14. Aug 10, 2004 #13
    I admit I didn't do much QED, but I still don't get how an E field can curve a EM wave. Is this like a G field in general relativity? Does it have to do with e+ e- pair creation?
  15. Aug 10, 2004 #14


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    There is a major point here that seems to be overlooked. Light-light scattering/collision has an extremely miniscule cross-section. In fact, for any appreciable collision cross-section, one has to go to very high energy photons (gamma). Gamma-gamma collision, although has sound theoretical foundation, is still unrealized experimentally. We have no gamma-gamma collider - unless I've slept through the last 10 years. There are efforts to include the possibility of having a gamma-gamma collider in the design of the Next Linear Collider.

    This is the self-energy of the photon (or whatever particle that initiates this) within the many-body formulation. However, again note that as the interactions get more and more complex, these become higher order terms in the perturbation expansion. We need to be clear that these are theoretically possible, but physically unlikely or extremely difficult to detect. One can make all kinds of exotic higher-order interactions when drawing the feynman diagrams, but it doesn't mean that such interactions have any detectable effects. This last point is often missed, especially by quacks wanting to harness zero-point field vacuum energy.


  16. Aug 10, 2004 #15


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    And GRBs, and magnetars ... IIRC, the high energy astrophysics have hopes of detecting some footprints, maybe GLAST will find something?
    Last edited: Aug 10, 2004
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