Cuestion of black holes

  1. Clausius2

    Clausius2 1,479
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    It is said that nothing even the light can escape out of black holes.
    I have a little question: If the light cannot escape out of the black hole, how is it possible that there are planets and stars spining around them? The cause of this spinning is the force of gravity. Taking into account it is said that gravitational interaction is transported via gravitons (virtual particles). This particles go at light velocity. If this light cannot escape, the body spinning around black holes should not know this black hole is there, because black hole couldn't emit gravitons.

    It seems to me an enigma!.
     
  2. jcsd
  3. wolram

    wolram 3,730
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    http://archive.ncsa.uiuc.edu/Cyberia/NumRel/BlackHoles.html

    Predicted in Einstein's General Theory of Relativity, gravitational waves are disturbances in the curvature of spacetime caused by the motions of matter. Propagating at (or near) the speed of light, gravitational waves do not travel "through" spacetime as such -- the fabric of spacetime itself is oscillating. Though gravitational waves pass straight t hrough matter, their strength weakens proportionally to the distance traveled from the source. A gravitational wave arriving on Earth will alternately stretch and shrink distances, though on an incredibly small scale -- by a factor of for very strong sources. That's roughly equivalent to measuring a change the size of an atom in the distance from the Sun to Earth!

    this is a good site to learn more about BHs, as far as i know
    gravitons are still only theoretical.
     
  4. marcus

    marcus 24,112
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    good reply wolram. to corroborate what you say, "gravitons"
    are useful for analyzing small perturbations or ripples in basically flat space

    In situations like BH where space is highly curved, the approximations that are good with flat space dont work and
    one would not normally anaylize disturbances in grav field in terms of "gravitons".

    In a GR or quantized GR (LQG) analysis of BH, I have not seen any reference to graviton. Lots of analysis of dynamic disturbances of field but no hint that "graviton" even exists "theoretically" because it is not a basic object that would be useful for describing nature (except in the slightly perturbed flat space situation where it IS mathematically useful to assume it exists and talk a bout it).

    My advice to Clausius would be not to worry about "graviton" around black holes since the people who analyze behavior about ordinary sorts of BH do not need or use the idea of "graviton"
    at least in papers I have seen.

    But in approximative case of almost flat space the idea IS extremely useful. so a lot depends on context
     
  5. Clausius2

    Clausius2 1,479
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    Well, i've read your answers, but i'm not very happy with it, because they are causing me a headache. My next question is:
    I heard the gravitational interaction is explained in terms of gravitonts (like electromagnetic in terms of virtual photons). To be honest, i heard another explain but only in general relativity, that involves the curvature of the space-time, something like a constraint that obbeys the body to run along an orbital way.
    Which of these two explanations is the correct?
    Nobody are detected virtual photons, except for their effects (electromagnetic force), because are undetectables!
    Perhaps are the two explanations in some way equivalents?
    is this what the physics call the cuantical gravitation?
    I've heard about the radiation emitted for the blackholes, but in fact, this radiation comes from out of the hole indeed. The hole acts like an unidirectional membrane in this case too.
    I think gravitons would be undetectables, perhaps by the Heisenberg's principle, but we suppose it like a truth and it doesn't go contrary to none of the physics laws, so it doesn't matter to do that.
    is it relationed with holografy? The boundary of the black hole would seem to contain the mass information that is inside it, so gravitational force between a star and the black hole could be possible.
    One of this explanation is more "edible" than the other. The curvature of space time perhaps is less understable in terms of classical interaction. I see easier there is some strange particles that carry over the space the essential information of the body, like its mass.
    Although perhaps they are the same!!
     
  6. wolram

    wolram 3,730
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    http://www.wikipedia.org/wiki/Graviton

    From Wikipedia, the free encyclopedia.


    The graviton is a hypothetical elementary particle that transmits the force of gravity in most quantum gravity systems. In order to do this gravitons have to be always-attractive (gravity never pushes), work over any distance (gravity is universal) and come in unlimited numbers (to provide high strengths near stars). In a quantum theory this defines an even-spin (spin 2 in this case) boson with a rest mass of zero.
    ---------------------------------------------------------------------
    Quantum gravity is the field of theoretical physics attempting to unify the subjects of Quantum mechanics and General relativity.

    Much of the difficulty in merging these theories comes from the radically different assumptions that these theories have on how the universe works. Quantum mechanics depends on particle fields embedded in the flat space-time of either Newtonian mechanics or special relativity. Einstein's theory of general relativity models gravity as a curvature within space-time that changes as mass moves. The most obvious ways of combining the two (such as treating gravity as simply another particle field) run quickly into what is known as the renormalization problem. Gravity particles would attract each other and if you add together all of the interactions you end up with many infinite results which can not easily be cancelled out. This is in contrast with quantum electrodynamics where the interactions do result in some infinite results, but those are few enough in number to be removable via renormalization.
     
    Last edited: Sep 24, 2003
  7. wolram

    wolram 3,730
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    i hope this helps clausius2,

    gravity is a non intuitive subject, there are many theories
    from crackpot to mainstream, i consider MARCUS and other
    mebers of this forum very knowledgable in this field,
    theoretical things such as gravitons are a useful tool
    that aid in some theories, but like a lot of things
    they are not yet prooven to exsist.
     
  8. wolram

    wolram 3,730
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    Hawking radiation is radiation (particle-antiparticle radiation) emitted by black holes. It is named after British physicist Stephen Hawking who worked out the "theoretical argument" for its existence.


    Black Holes are sites of immense gravitational attraction into which surrounding matter is drawn by gravitational forces. It was originally thought that the gravitation was so powerful that nothing, not even radiation, could escape from the Black Hole, but Hawking theorized that (particle-antiparticle) radiation would be emitted as matter spiralled into the Black Hole and approached the event horizon (the boundary beyond which nothing would return).
    --------------------------------------------------------------------
    please note, hawking who worked out the "theoretical argument".
     
    Last edited: Sep 24, 2003
  9. As I understand it, Black Hole theory exist only in theory and the only measurement of a suspected black hole so far, produced a result 10 times greater than predicted by Hawking.
    Surely this puts it on the the same quality level as the theoretical graviton.
    On http://elasticity2.tripod.com/s38.htm I show a simple explanation of where the graviton fits into the fundamental particle structure (scroll down to figs 39.2-5). Note the my arguement works in both the Standard Model of particle physics as well as my (crackpot) idea of a Single Force model, but it only makes sense in the Single Force Model.
    It might help to understand what I am trying to say by looking at it as a Reverse (or anti-) gravity Theory that can be reached by reversing the plus/minus signs of quantities and directions in current theory.
     
    Last edited by a moderator: Sep 25, 2003
  10. Nereid

    Nereid 4,014
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    Would you be so kind as to provide a reference/link?

    I'm sure others will jump in with lots and lots of links; IIRC the observational support includes, in approx order of certainty (roughly, 'can't be anything else but a BH'):
    - CygX-1
    - several other X-ray binaries
    - centre of the Milky Way galaxy
    - nucleus of several other nearby galaxies
    - heart of quasars
     
  11. wolram

    wolram 3,730
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    http://chandra.harvard.edu/photo/2003/ngc1068/

    http://universe.gsfc.nasa.gov/press/2003/030410e.html

    http://www.universetoday.com/am/publish/blackholes.html

    http://cosmology.berkeley.edu/Education/BHfaq.html#q7

    http://csep10.phys.utk.edu/astr162/lect/active/smblack.html

    ----------------------------------------------------------------------------------------------

    there is to much evidence for the existence of what scientists call
    black holes for them to be dismised, what they are is debatable.
    i would like to see any evidence of there nonexistence.
     
  12. wolram

    wolram 3,730
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    ELAS, you have done a lot of work on your theory, but maybe
    this thread is not the place to advertise it, perhaps you
    could get it published or get it reviewed by someone of
    noted standing, if not then it will join the long list
    of forgotten theories.
    i wish you all the best .
     
  13. Phobos

    Phobos 2,020
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    Correct. Start a new topic in the "theory development" forum. You can post a link to that topic here.
     
  14. I did not intend to advertise but to answer a point raised by Clausius2, who started the forum -

    "I heard the gravitational interaction is explained in terms of gravitonts"

    I intended to show that in current Particle Physics Theory it is possible to find a place for the graviton. Clausius2 seems to be of the opinion that the graviton is limited to Relativity or Astrophysics. That is why I was careful to point out that the graph referred to is not restricted to my own proposals but applies equally to the Standard Model. The data used to construct the graph was taken fromThe Particle Explosion, a well known and often quoted Particle Physics book.

    My point is that the Standard Model already uses the data necessary to unite Relativity and Quantum Physics, it is just a question of how you arrange the data for display. You do not need my ideas to do this; but I could not resist the tempation to say "you need my ideas to explain it".

    I note the Forum Mentor's comment and will not subscribe further unless requested to do so by Clausius2. My thanks to wolram for his reply.
     
  15. Clausius2

    Clausius2 1,479
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    great job, elas!. But in Spain there is an expression that says: "the honey hasn't been done for ass". I mean, I cannot understand your article on the complete right way, because i'm not a physic. I belong to the mass public. After all, i've understood your answers more or less, so thank you for your efforts.
     
  16. the only measurement of a suspected black hole so far, produced a result 10 times greater than predicted by Hawking
    Please provide link

    Sorry cannot supply link. When the first report of a sucessful measurement appeared in New Scientist it stated that the diameter was ten miles and Hawking had predicted one mile for the same body.
    The use of miles indicates that the work originated in the USA.
     
  17. pmb

    pmb 0

    See -- http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/black_gravity.html

    Pete
     
  18. Clausius2

    Clausius2 1,479
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    In your link you say:
    "In addition, however, virtual particles aren't confined to the interiors of light cones: they can go faster than light! Consequently the event horizon, which is really just a surface that moves at the speed of light, presents no barrier."

    Oh,no! It's horrible. Now, i don't undertand nothing. It was said that nothing could go faster than light!.
    It is puzzling me!
     
  19. pmb

    pmb 0

    Nothing can be detected to travel faster than light. These are virtual particles and therefore they cannot be detected. Therefore they can't be used to send information faster than light.

    Pete
     
  20. Clausius2

    Clausius2 1,479
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    your answer doesn't like me at all.
    Let's see your telling:
    -We suppose virtual particle going faster than light, so the gravity can "get out" of the black hole, and be felt by anybody around it.
    -Now you say this particle are virtual, because can't be detected.Therefore they can't transport any information.

    >>>>>Therefore there is a contradiction, then the black hole could not be felt by nothing if the phenomena is not described in terms of General Relativity.

    Sorry if i am too heavy.
     
  21. pmb

    pmb 0

    An oberver inside the horizon cannot communicate with observers outside the horizon by using virtual partilces. That does not mean that virtual particles can't get out.

    Pmb
     
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