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Are black holes bosons or fermions?

  1. Apr 30, 2009 #1
    The question says it all. Black holes have mass, and they
    have angular momentum.
    - Is the angular momentum an integer or half an integer? Or neither/both?
    - What happens when two black holes are exchanged?

    François
     
  2. jcsd
  3. Apr 30, 2009 #2
    If bosonic matter collapses, it can create a Black Hole, and from what I've read, Black Holes emit fermions.

    I am not completely sure though, as this is out of my league.
     
  4. Apr 30, 2009 #3

    Borek

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    Angular momentum and spin are different things.

    Disclaimer about the league holds here as well.
     
  5. Apr 30, 2009 #4

    Fredrik

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    The definition of particles in QM comes from the theory of representations of the Poincaré group, or to put it another way, the particle concept is very intimately connected to the properties of flat spacetime. So it doesn't seem to make much sense to try to apply the defintition of a particle to a black hole.
     
  6. Apr 30, 2009 #5
    this is because of virtual particles they have been discussed many times in many forums but briefly, they are particle/antiparticle pairs that are created in a vacuum with no energy from quantum fluctuations that usually annihilate and return the borrowed energy but, just one of these particles can cross the event horizon leaving the other and it appears as if the black hole is radiating particles
     
  7. Apr 30, 2009 #6

    ZapperZ

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    Can you first of all tell if, say, the earth is a boson or a fermion?

    If you can't answer that, or if the question really is meaningless, then how are we supposed to be able to answer something that is even MORE EXOTIC?

    Zz.
     
  8. Apr 30, 2009 #7
    I don't think anyone knows enough to say exactly what is black hole is yet, but considering it's a collapsed star it seems unlikely we can characterize it quite so simply. And the incredibly high entropy of a typical black hole suggests its a lot more than either a boson or fermion....It does not seem we'll have much of an understanding of singularities until we get quantum theory and relativity combined or somebody comes up with something even more insightful....
     
  9. Apr 30, 2009 #8

    Fredrik

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    I think his point was that according to the theory, the properties of a black hole are completely represented by a short list of numbers: mass, charge and angular momentum. The only other objects in the universe that can be characterized this way are elementary particles. So black holes have a lot in common with particles, while the Earth doesn't.
     
  10. May 1, 2009 #9
    The Earth is a boson. Fermions are only the same after rotations by 4 pi, the Earth is the same after 2pi, I would say.

    François
     
  11. May 1, 2009 #10

    ZapperZ

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    Really! Yet, I can distinguish the earth rather easily and track it's path, etc. Did you not care about the indistinguishibility of bosons when you make such a statement? What statistics did you use to arrive at such a conclusion? It certainly isn't QM.

    Can you also please tell me the "spin quantum number" of the Earth?

    Zz.
     
  12. May 1, 2009 #11

    ZapperZ

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    So can a lot of classical objects!

    Yet, the term "angular momentum" for quantum particles take on a DIFFERENT meaning than classical objects. Did we settle already that classical angular momentum is the SAME thing as quantum angular momentum? Since when?

    And since when can a non-coherent composite object be considered a boson or a fermion? Look at any composite bosons that we know of. What is the MAIN criteria for that whole entity to be considered as a composite boson? Need an example? Look at the Cooper pairs.

    Zz.
     
  13. May 1, 2009 #12

    Fredrik

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    That its Hilbert space is the representation space of an irreducible representation of the Poincaré group?
     
  14. May 1, 2009 #13
    No, spin-statistics doesn't need the existence of a rep of the Poincare group. It only needs the existence of antiparticles.
     
  15. May 1, 2009 #14
    How about if we consider black holes that are really mini, instead of a classical ones...
     
  16. May 1, 2009 #15

    ZapperZ

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    Then show me the difference between an "ordinary" liquid helium He4 in "normal" phase versus the superfluid phase. Why does it have to go below some critical temperature for the BE condensation to take place if "the whole earth" is a boson already?

    Zz.
     
  17. May 1, 2009 #16

    Fredrik

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    I can't answer that, since I haven't studied superfluidity, and I most certainly haven't suggested that the Earth is a boson. :smile:
     
  18. May 5, 2009 #17
    A black hole would be a fermion because it is made of matter. Bosons are generally force carriers, so this means that black holes emit fermions (gravitons). I'm pretty sure I'm right here, but please tell me if I'm wrong...I'm learning too!
     
  19. May 5, 2009 #18
    if gravitons exist, they are bosons with a spin of 2
     
  20. May 6, 2009 #19

    ZapperZ

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    He4 is "matter", and so are Cooper pairs. Yet, they are BOSONS. This fact already falsified what you wrote.

    Zz.
     
  21. May 6, 2009 #20

    malawi_glenn

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    how big are classical black holes?
     
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