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Thread: How fast can a black hole move?

  1. #1 How fast can a black hole move? 
    Time Lord
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    If I'm not mistaken, there's sort of an inverse rule on mass and momentum, isn't there? More massive objects suffer the effects of relativity at lower speeds, so it would be much easier, for example, to accelerate an electron to .99 C, than to accelerate a proton to that speed?

    The reason light can move at C is because it has no rest mass. Shouldn't a black hole, then start to feel the effects of relativity at very low speeds?


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  3. #2 Re: How fast can a black hole move? 
    Forum Senior Booms's Avatar
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    Quote Originally Posted by kojax
    The reason light can move at C is because it has no rest mass. Shouldn't a black hole, then start to feel the effects of relativity at very low speeds?
    I was under the impression light and black holes were as opposite as you could get, light has no rest mass, black holes are entirely mass, I would have thought black holes moved exceptionally slowly, if at all


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  4. #3 Re: How fast can a black hole move? 
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    Quote Originally Posted by Booms
    Quote Originally Posted by kojax
    The reason light can move at C is because it has no rest mass. Shouldn't a black hole, then start to feel the effects of relativity at very low speeds?
    I was under the impression light and black holes were as opposite as you could get, light has no rest mass, black holes are entirely mass, I would have thought black holes moved exceptionally slowly, if at all
    Yeah. That's a better way of describing it. A black hole should hardly move at all, if I'm not mistaken, but I want to confirm that.
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  5. #4  
    Forum Radioactive Isotope MagiMaster's Avatar
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    Why? A black hole has a finite mass, so it still follows F=ma and the conservation of momentum.
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  6. #5  
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    Yes, a blackhole is still only as massive as several large stars, in most cases, and can move in much the same manner as a star of 10-50 solar masses or however massive the blackhole is.
    Wise men speak because they have something to say; Fools, because they have to say something.
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  7. #6  
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    When the LHC debate was going on, one of the arguments claiming it was safe was that cosmic rays hitting the atmosphere would form a micro black hole, but the earth was still here. But the counter argument was that these black holes would keep moving at the speed of the cosmic ray, so we couldn't be sure if they were safe. I don't know if it's right, but that suggests they can move, and pretty quickly. Then again, it's only a micro black hole.
    The wise man believes half of what he reads. If he knew which half to believe, he'd be a much wiser man.
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  8. #7  
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    Quote Originally Posted by Arcane_Mathematician
    Yes, a blackhole is still only as massive as several large stars, in most cases, and can move in much the same manner as a star of 10-50 solar masses or however massive the blackhole is.
    But, how fast can one of those move?
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  9. #8  
    Veracity Vigilante inow's Avatar
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    Relative to what?
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  10. #9  
    gc
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    Quote Originally Posted by inow
    Relative to what?
    Exactly.

    A black hole can move at the speed of light relative to a photon :wink:
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  11. #10  
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    Quote Originally Posted by gc
    Quote Originally Posted by inow
    Relative to what?
    Exactly.

    A black hole can move at the speed of light relative to a photon :wink:
    You mean relative to a photon at its core, or relative to a photon far away from the nearest gravity well?
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  12. #11  
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    It can move at nearly light speeds. As a matter of fact, it can approach the speed of light. It just can't reach the speed of light. I suppose, if you really want to know how fast it can go, first you'd have to know the mass of the black hole and how much other matter and energy there is in the universe. Then, you'd have to pick a reference frame. Then, calculate the amount of energy you can pump into it, and plug it in to the kinetic energy equation.
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