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Magnetic Monopoles detected? Mayhaps

  1. Oct 2, 2003 #1

    Apparently the physicists claimed they observed the fingerprint of a monopole in momentum space?
  2. jcsd
  3. Oct 3, 2003 #2
    I told you so!
  4. Oct 3, 2003 #3
  5. Oct 3, 2003 #4
    btw isnt it meaningless to say: "north or south magnetic pole" because there is only one pole and it's not relative to other pole as for example a simple magnetic is.
  6. Oct 3, 2003 #5
    I'm not sure how they would classify monopoles, unless they expose it to a known magnetic dipole and observe what it behaves as, but other than that, I can't provide any further answer to how they could classify a monopole as north or south.
  7. Oct 3, 2003 #6


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    "north" and "south" are just synonyms for positive and negative. (not necessarily in that order)
  8. Oct 3, 2003 #7
    Quote from the magnetic monopoles article:

    "The researchers also measured the transverse optical conductivity of a thin film of the crystal using a technique known as high-resolution Kerr microscopy and found a sharp peak at low energies. According to Tokura and co-workers, this peak can only be explained by the presence of monopoles in the band structure of the crystal."

    Anybody care to explain what a Kerr microscopse is?
  9. Oct 3, 2003 #8
    Monopoles are supposed to have arisen from inflation, according to Alan Guth. Why monopoles? What type of electric circuit corresponds to a monopole? Might they occur as virtual entities, with +/- separate only within the bounds of the HUP?
  10. Oct 4, 2003 #9
    Loop Quantum Gravity: By saying "I told you so" to Brad_Ad23, I did not mean that I had previously said that they'd been found, but that I had previously said that I think they exist (and not yet found [to my knowledge] until now.)
    Last edited: Oct 4, 2003
  11. Oct 4, 2003 #10
    Yeah that did confuse me a bit as well.

    Anywho, I had a post for a few posts up, but couldn't post it, but here it is:

    First off, monopoles are the magnetic equivalent to a pure positive or
    pure minus electric charge. You may be familiar that the electric force
    and magnetic force are combined into the electromagnetic force. Yet, they
    appear to exhibit a bizzare asymmetry. We can easily get single charges,
    but never single magnetic poles. Plus always comes with minus. To
    isolate a single monopole would be quite an achievement and verify several
    predictions made by several GUTs.

    As for Kerr Microscopy:



    Those should tell you what Kerr Microscopy and what a Kerr Microscope are
  12. Oct 5, 2003 #11
    There can be no monopoles.

    Since more than 50 years it is known that, what we call magnetism, is in fact a relativistic side effect of the electric field. So there can only be apparent dipoles.

    This was exactly mathematically proven by e.g. Rosser, Electromagnetism by Special Relativity, Butterworth, London.
  13. Oct 5, 2003 #12
    Experiment rules over mathematical proof, except in this case where the experiment is not conclusive, then it is up for speculation, so therefore, one can't outright say they do/don't exist. Keep in mind that absence of evidence is not evidence of absence.
  14. Oct 5, 2003 #13


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    Claims of mathematical proof are highly suspect as well because theories permitting monopoles (such as Dirac's symmetrized Maxwell equations, for an elementary example) exist.

    In fact, in Dirac's symmetrized Maxwell equations, if nonzero magnetic and electric charges have the right relationship, the theory is physically indistingusihable from the ordinary Maxwell equations, so no such proof can exist.
    Last edited: Oct 5, 2003
  15. Oct 6, 2003 #14
    That is true! However from the Maxwell theory together with the Lorentz transformation it follows that magnetic monopoles cannot exist. (Refer to the book of Rosser mentioned above).

    So, if magnetic monopoles are found it has severe consequences:
    - Either the Maxwell theory is wrong
    - Or Special Relativity is wrong

    In both cases we will have to re-think main areas of physics.
  16. Oct 6, 2003 #15
    Or, neither are wrong. If other theories which are consistent to exist that incorperate both Maxwell and hence SR, and have monopoles, such as the aforementioned Dirac equations, then what do we have? Why it looks like different formulae for the same phenomenon, only each looking at certain conditions maybe? I would say that is more accurate. In physics, mathematical proof is merely an interesting footnote, albeit an important footnote.
  17. Oct 6, 2003 #16
    Evaluation of the Lorentz transformation shows that the magnetic field is a relativistic side effect of the electric field. If we would have magnetic monopoles in addition then we would have two independent causes of magnetism.

    The Lorentz transformation fully explains the magnetic phenomena as given by Maxwell. If we now have an additional source of magnetism which would give an additional contribution to the magnetic field, the Maxwell equations can no longer be correct.
  18. Oct 6, 2003 #17
    But then how can the Dirac version even exist? And as an aside, I am curious if the math you speak of takes into account any quantum effects. IIRC, monopoles arise on a quantum level.
  19. Oct 6, 2003 #18
    The relativistic requirement of Lorentz invariance requires that derivatives in space in time all appear to the same order, since all four coordinates must be treated on equal footing. The K-G equation illustrates that an expression which satisfies this condition but is non-linear in the space and time derivatives gives rise to anomalous results. Dirac set out to find an equation which was first order in space and time derivatives. The result of his efforts, the Dirac equation, is difficult to motivate, impossible to prove, and far more complicated that the non-relativistic analog, but it has been shown to work, and satisfies all the requirements of special relativity and quantum mechanics.

    So what does Dirac have to do with Monopoles is my question!?
  20. Oct 7, 2003 #19


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    Check out this Wikipedia definition. Dirac showed that if there was even one magnetic monopole in the universe, then electric charge would have to be quantized. Which it is, of course and which ordinary quantum theory does not explain.
  21. Oct 8, 2003 #20
    Is the reverse conclusion correct? That means if the electric charge is quantized then there must be magnetic monopoles?

    It is a property of the magnetic field that, if we notice to be in a field and we move with an appropriate velocity into an appropriate direction, the magnetic field will disappear.

    Now assume that you are at the side of a magnetic monopole. Then you will also be able to move in a specific direction so that you will not notice the field any longer. So you see a magnetic monopole which has no magnetic field.

    What is about that?
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