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Charge in a black hole?

  1. Dec 3, 2012 #1
    Lets say an electron crosses the event horizon of a black hole.
    Now as it starts speeding up when it gets closer to the center of the black hole
    its B field will increase. Does this increased B field exist outside the event horizon?
  2. jcsd
  3. Dec 3, 2012 #2


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    Staff: Mentor

    No. Changes in electrical and magnetic fields propagate at the speed of light, and even light cannot cross the horizon outwards. Equivalently, all the effects of the electron's motion are in its future lightcone, and after the electron crosses the horizon no part of that lightcone lies outside the horizon.
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