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Are black holes theoretical or real?

  1. Jun 30, 2011 #1
    The news always depicts them as real

    http://www.bbc.co.uk/news/science-environment-13964767

    But as far as I gather from reading this forum and wikipedia, blackholes are always said to be "candidates"

    Has it been proven "beyond a reasonable doubt" that they exist?
     
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  3. Jun 30, 2011 #2

    phinds

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    SOMETHING exists that exhibits the characteristics which we attribute to a thing that we call black holes for want of a better term
     
  4. Jun 30, 2011 #3
    So you say, apparently in favoring the idea that blackholes have been positively measured. I'd be truly shocked to see you or anyone provide evidence to support the claim that black holes exhibit measurably different characteristics from incipient black holes. Shock me.
     
  5. Jun 30, 2011 #4
    "Exist" has no well defined meaning in general relativity. Existance is relative, to be blunt.
     
    Last edited: Jun 30, 2011
  6. Jun 30, 2011 #5

    hunt_mat

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  7. Jun 30, 2011 #6

    PAllen

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    It think what you say is true, but maybe not for much longer. There are observational programs under way to directly observer whether the hypothesized black holes in the milkyway or Andromeda have true event horizons. Within a decade, this will likely be settled observationally. This will distinguish between quantum gravity models where the event horizon never actually forms, versus those prevent the singularity but not the event horizon.
     
  8. Jun 30, 2011 #7

    George Jones

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    Yes, see the fascinating article "Portrait of a Black Hole",

    https://www.cfa.harvard.edu/~loeb/sciam2.pdf.
     
  9. Jun 30, 2011 #8

    russ_watters

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    Isn't that hairsplitting? At least grammatically, one is a subset of the other!

    I agree with phinds: "black holes" exist because that's the name we have chosen for a certain set of observations. That does not imply - nor should it be required to - that that set of observations is fully understood.
     
  10. Jul 1, 2011 #9
    Black holes are obviously thoretical and that is IMO clearly stated in most articles, included the one in the OP where they make clear they are talking about a quasar or in the Sciam article linked by George jones where they specifically talk about this distinction.


    This is important, not only this but the theoretical black hole is just the current interpretation of the consequences of the EFE under certain assumptions. We have no way of knowing if in the future those assumptions might change and the EFE of GR may lead to different interpretations of the observations, whether it is thru some Quantum gravity theory yet to be developed or something similar.
     
  11. Jul 5, 2011 #10
     
  12. Jul 5, 2011 #11
    Do you have a link I could visit for more information? I'm not sure what to get out of this. You seem to be saying we could have observational evidience in a decade or so whether one or more black hole candidates have a measurable event horizon. What you say could be interesting.
     
    Last edited: Jul 5, 2011
  13. Jul 5, 2011 #12

    russ_watters

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    Care to elaborate? Ie, do you think "apple pie" is a subset of "pie"?
     
  14. Jul 5, 2011 #13

    PAllen

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    George Jones gave a link to the Scientific American article on this. I believe that has pointers to the primary literature.
     
  15. Jul 5, 2011 #14

    bcrowell

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    By analyzing millimeter and infrared very-long-baseline-interferometry observations, Broderick, Loeb, and Narayan http://arxiv.org/abs/0903.1105 have shown that if Sagittarius A* had a surface, then the luminosity of this surface must be less than 0.3% of the luminosity of the accretion disk. But this is not physically possible, because there are fundamental limits on the efficiency with which the gas can radiate away its energy before hitting the surface. We can therefore conclude that Sagittarius A* must have an event horizon. As PAllen noted, its event horizon may be imaged directly in the near future: http://arxiv.org/abs/0906.4040
     
    Last edited by a moderator: Apr 26, 2017
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