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What force is stronger, Gravity or Magnetism?

  1. Mar 2, 2006 #1
    What force is stronger, Gravity or Magnetism?

    I know that magnetism in general is stronger here on earth but what about by the event horizon of a super massive black hole?
  2. jcsd
  3. Mar 3, 2006 #2


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    Welcome to PF, JBash! What do you think? Small magnets lift objects off tables so the logical conclusion is magnetism is more powerful than gravity on earth. At the event horizon of a black hole . . . hard to say. I would guess the black hole has no intrinsic magnetic properties, however the inspiraling particles could acquire enormous magnetism.
    Last edited: Mar 3, 2006
  4. Mar 3, 2006 #3


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    Since the gravity potential is much smaller at the EH of a massive BH than it is around a smaller BH, it would be magnetism, if you mean the electromagnetic force holding elements together. The smaller the BH, the stronger the gravity at the EH, and a particularly small BH that is small enough to be emitting big-time Hawking radiation is where gravity would probably overwhelm the EM force.

    Someone can probably compute at what size/mass for the BH this "swap" would take place, but it ain't me..:cry:

    EDIT: If you mean the electromagnetic field around the BH (all BH's have an EM field) then it is very weak so in almost all cases the gravity would be stronger than the EM field.
    Last edited: Mar 3, 2006
  5. Mar 3, 2006 #4
    Thank you both for your kind responses...

    This leads me to another question?

    When BH's "feed" sometimes they will shoot (jet) matter outward- in opposite the direction (where I have learn almost as fast as the speed of light) does this have anything to do with Magnetism?

    While a BH's gravity pull is obviously very strong, is it strong enough to seperate magnetic poles within particles and if so, would BH be polar?
  6. Mar 3, 2006 #5


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    There's a mish-mash of misunderstanding here.

    It's not the BH which 'shoots matter outward', that comes from the matter that's well outside the BH's event horizon.

    When stuff (matter, other than dark matter) starts to 'go down the BH drain', a great deal of it ends up in an accretion disk (Google on this term), due to a combination of very well known and well understood physical processes.

    What happens in such accretion disks is a topic of great interest to astrophysicists, and there are many who are actively working on this.

    One approach is to combine plasma physics (specifically, MHD) with gravitational theory (Newtonian will do, but GR is better), to see what happens. One object of this work is to create models which accurately reproduce what astronomers observe - polar jets.

    In these models, magnetic fields do play an important role ... after all, what does the 'M' in 'MHD' stand for?
    I'm not sure I follow your question here ... however, magnetic monopoles have not been detected, either in the lab or in astronomical observations.

    Such critters do appear in various theories, that go beyond the Standard Model of particle physics.

    Whether there are certain regimes near the event horizons of (relatively) low-mass BHs which can produce the kinds of magnetic monopoles of the various theories that predict them, well, I myself don't know.

    But even if there is such a prediction, I'd say it'll be a couple of decades (at least) before there's enough observational and experimental results to move such ideas from speculation to a more firm basis.
    Last edited: Mar 4, 2006
  7. Mar 4, 2006 #6


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    Nereid puts it well, as usual. The jets observed from AGN, and blackholes, originate far from anything you could characterize as the 'event horizon'. Matter gets smoking hot via collisions as it inspirals long before it reaches the gravitational seed.
  8. Mar 12, 2006 #7
    what is the rotation direction af a BH?
    i have a question that if a matter fall in to a BH what will happen to it?
    will it be transformed in to light?
    can some body explain to me the relation between the light-coin thery with the BH.
    will BH can be a SWAPHOLE that can go through the time theologically?
    i don't know much about physics but i ask depend on my common sense.
    please don't laugh if i ask wrong.
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