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Why are magnetic monopoles so heavy?

  1. Sep 16, 2012 #1
    My question is in two parts. What is the origin of the electric field from an electric charge and why electron can have so small mass? While on the other hand for a magnetic monopole to create a magnetic field needs to be so heavy? And if the magnetic monopole is a hadron what are the constituent elementary particles ? A simple undergrad level answer will do.
  2. jcsd
  3. Sep 16, 2012 #2
    We pretty much just *define* electric charge as whatever serves as a source of electric fields.

    Small compared to what?

    I don't think there's any a priori requirement that magnetic monopoles be heavy. But since we haven't found any, if they exist they must be heavier than the heaviest particles we can currently produce at accelerators. Monopoles often turn up in hypothetical "grand unified theories," which usually postulate new physics at very high energies. Thus the new particles they describe are very massive.

    Hadrons are things made of quarks. Quarks (like all known particles) have no magnetic charge, so hadrons cannot be magnetic monopoles. If magnetic monopoles exist, they could be composite, but they would have to be composed of currently-unknown constituent particles.
  4. Sep 16, 2012 #3
    My question for the origin of the field is: does it come somehow from the vacuum and is there relation to the mass?
    The monopoles are extremely heavy for particles and there is no problem to be made up of quarks (or at least there are lots of papers about this), many quarks maybe? There binding energy is huge but not compared to 10^16 GeV mass of monopole. Electron has only 0.5MeV. Monopole mass is inversely proportional to the unification length in the GUT theories but that does not explain it.
    The energy produced by the charges will need to be balanced somehow so they do not explode ?
  5. Sep 16, 2012 #4
    I'm not sure what that would mean. Fields come from charges.

    No, charge is independent of mass. Charged and uncharged particles of any mass can exist.

    Magnetic monopoles can't be made of standard, known quarks because the known quarks have no magnetic charge. It doesn't matter how many quarks you put together. I'd be surprised to find a paper showing otherwise; do you have a link?

    This does explain why the monopoles in GUTs are so heavy. As I mentioned above, all the new physics in GUTs is generally at the unification scale of around 10^16 GeV; that is, all the new particles introduced have masses around this value.

    If there are magnetic monopoles, I believe there is a law of conservation of magnetic charge, which means that the lightest magnetic monopole particle will be stable and will not decay.
  6. Sep 16, 2012 #5
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