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Energy and fields

  1. May 20, 2008 #1

    zonde

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    Hi!

    After considering some aspects of modern physics I found out that there are some pieces that does not fit in my mind very well.
    So I'd like to ask some questions here.
    Is it right that for matter to produce fields it requires to radiate out energy?
    And if yes then from where comes this energy?
     
  2. jcsd
  3. May 20, 2008 #2

    malawi_glenn

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    Are you referring to Field quanta's?
     
  4. May 20, 2008 #3

    zonde

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    Not necessarily
    But maybe for simplification of discussion it will be better to refer to quantas.
     
  5. May 26, 2008 #4

    zonde

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    Maybe another question.
    Gravitation is propagating at speed of light.
    Nothing moving at light speed that is inside the event horizon of black hole can get outside it.
    Question is how black holes can produce gravitation around them?
     
  6. May 26, 2008 #5

    malawi_glenn

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    It depends on your description of gravity, if gravity is mediated by massless gauge bosons, or not.

    Black holes can not be described, as of yet, by quantum physics. That is why the hottest field of reserach today is to fuse gravuty and quantum physics, one of these trials is String theory.

    Dont ask new, unrelated, questions in the same thread. It is better to make new one or search for old ones in order to keep the forum clean.
     
  7. May 26, 2008 #6
    No it is not. Only when you move the body, the surrounding field starts to wiggle and the energy that was used to move the body is carried away in the waves that move through the field.
     
  8. May 26, 2008 #7

    zonde

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    Energy is required to accelerate body but not to move it. Can you please clarify your idea?
     
  9. May 26, 2008 #8
    Clarification: nonuniform, accelerated motion of the body.
     
  10. May 27, 2008 #9

    zonde

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    It sounds like you are saying that fields exist on their own but are not produced by matter. Does not sound very sensible to me.
     
  11. May 27, 2008 #10
    Why is that not sensible to you?
     
  12. May 27, 2008 #11

    zonde

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    Because fields describe interactions between matter that maintains it's intensity and orientation relative to the interacting parts. So fields look like continuous stream of something and not like something that is altered time by time.
    I hope that this description makes sense.
     
  13. May 27, 2008 #12
    Yes. E.g. suppose you have a system of charges which is initially at rest. In general there will exist a static eletric field in the region in and around the system. If you try to wiggle some of the charges then it will require yo to do some work on the system. The energy that you expel in wiggling the charges will go into the kinetic energy of the charges, the change in the energy of the field, the creation of magnetic fields and it will also generate and electromagnetic waves which will carry some of the energy away.

    Pete
     
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