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Thread: Would a collapsing black hole have a positive charge?

  1. #1 Would a collapsing black hole have a positive charge? 
    Time Lord
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    This kind of comes out of http://www.thescienceforum.com/viewt...23939&start=15

    In a strong gravitational field, protons weigh more than electrons because they have more mass, but they experience exactly the same amount of electrostatic repulsion as electrons do, because they have exactly the same charge.

    So, I'm thinking that, in the last stages of collapse, as the gravitational field is getting stronger and stronger, and mass is getting thrown out to prepare for the transition, wouldn't there be more electrons than protons in that ejection?


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  3. #2 Re: Would a collapsing black hole have a positive charge? 
    . DrRocket's Avatar
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    Quote Originally Posted by kojax
    This kind of comes out of http://www.thescienceforum.com/viewt...23939&start=15

    In a strong gravitational field, protons weigh more than electrons because they have more mass, but they experience exactly the same amount of electrostatic repulsion as electrons do, because they have exactly the same charge.

    So, I'm thinking that, in the last stages of collapse, as the gravitational field is getting stronger and stronger, and mass is getting thrown out to prepare for the transition, wouldn't there be more electrons than protons in that ejection?
    Black holes do not collapse.


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  4. #3 Re: Would a collapsing black hole have a positive charge? 
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    Quote Originally Posted by kojax
    This kind of comes out of http://www.thescienceforum.com/viewt...23939&start=15

    In a strong gravitational field, protons weigh more than electrons because they have more mass, but they experience exactly the same amount of electrostatic repulsion as electrons do, because they have exactly the same charge.

    So, I'm thinking that, in the last stages of collapse, as the gravitational field is getting stronger and stronger, and mass is getting thrown out to prepare for the transition, wouldn't there be more electrons than protons in that ejection?
    First, DrRocket is right. But if you replace "collapsing black hole" with "collapsing star", the answer is NO. A neutron star is already a product of a collapsing star. The strong pressure pushes the electrons into the atomic nuclei. As a result, the reaction of inverse beta decay produces neutrons.
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  5. #4 Re: Would a collapsing black hole have a positive charge? 
    Time Lord
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    Quote Originally Posted by Dishmaster
    Quote Originally Posted by kojax
    This kind of comes out of http://www.thescienceforum.com/viewt...23939&start=15

    In a strong gravitational field, protons weigh more than electrons because they have more mass, but they experience exactly the same amount of electrostatic repulsion as electrons do, because they have exactly the same charge.

    So, I'm thinking that, in the last stages of collapse, as the gravitational field is getting stronger and stronger, and mass is getting thrown out to prepare for the transition, wouldn't there be more electrons than protons in that ejection?
    First, DrRocket is right. But if you replace "collapsing black hole" with "collapsing star", the answer is NO. A neutron star is already a product of a collapsing star. The strong pressure pushes the electrons into the atomic nuclei. As a result, the reaction of inverse beta decay produces neutrons.
    Yeah, I said "collapsing black hole" because instead of "collapsing star" because I didn't want to be ambiguous about which stage of collapse I was talking about, but what you just said makes a lot of sense. I guess there's no reason a charge would ever build up, as long as neutral matter is falling in, because it just gets compressed into neutrons as well.
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  6. #5 Re: Would a collapsing black hole have a positive charge? 
    . DrRocket's Avatar
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    Quote Originally Posted by kojax
    Quote Originally Posted by Dishmaster
    Quote Originally Posted by kojax
    This kind of comes out of http://www.thescienceforum.com/viewt...23939&start=15

    In a strong gravitational field, protons weigh more than electrons because they have more mass, but they experience exactly the same amount of electrostatic repulsion as electrons do, because they have exactly the same charge.

    So, I'm thinking that, in the last stages of collapse, as the gravitational field is getting stronger and stronger, and mass is getting thrown out to prepare for the transition, wouldn't there be more electrons than protons in that ejection?
    First, DrRocket is right. But if you replace "collapsing black hole" with "collapsing star", the answer is NO. A neutron star is already a product of a collapsing star. The strong pressure pushes the electrons into the atomic nuclei. As a result, the reaction of inverse beta decay produces neutrons.
    Yeah, I said "collapsing black hole" because instead of "collapsing star" because I didn't want to be ambiguous about which stage of collapse I was talking about, but what you just said makes a lot of sense. I guess there's no reason a charge would ever build up, as long as neutral matter is falling in, because it just gets compressed into neutrons as well.
    Black holes are characterized (classically in GR nrglrcting quantum effects) by mass, angular momentum, and charge (see "no hair theorem"). Each is the sum of whatever has gonr to make up the black hole -- none of it is manufactured by the hole.
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  7. #6  
    Time Lord
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    Is that where Hawking Radiation comes from? Say an electron/positron pair forms at the event horizon of a black hole that has a strong net charge. One would be more strongly attracted than the other, right?
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