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Black holes

  1. Feb 7, 2004 #1
    why cant we make a black hole on earth. we know that a black hole comes into existence whenever a particles internal pressure becomes less than the outside pressure. the particle consequently collapses into itself and the creating a black hole, so why is it not possible on earth. then we can easily scientifically examine it. we can lessen the pressure by starting a process, either chemically or through laser, which will lessen the pressure. the question is is it possible?
     
  2. jcsd
  3. Feb 7, 2004 #2

    wolram

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    im sure black hole production is only a few years away
    i have read that it is possible.
     
  4. Feb 7, 2004 #3

    wolram

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  5. Feb 7, 2004 #4

    selfAdjoint

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    Dearly Missed

    Please redo URL.
     
  6. Feb 7, 2004 #5

    wolram

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    sorry SA, that link doesnt work and i have lost the site,
    but these work.
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    http://www.analogsf.com/0305/altview.shtml

    However, there are new theoretical predictions that when the new accelerator goes into operation, the LHC’s proton-proton collisions may also make something even more exotic: black holes. This column is about the possibility of black hole production at the LHC.
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    http://theory.fnal.gov/jetpold/talks/thomas.html
    Abstract
    Particle collisions at energies well above the Planck scale are believed to be dominated by the production of black holes. If the fundamental Planck scale is of order a TeV, as suggested in certain theories with large extra dimensions, microscopic black holes may be produced at the Large Hadron Collider at a rate of up to 1 Hz. Black hole production and decay leads to very dramatic events with a cross section which grows with a power of the energy. Standard hard scattering processes such as Drell-Yan or QCD jet production are also exponentially suppressed. Observation of these signatures would provide an experimental confirmation of the infrared--ultraviolet nature of quantum gravity, and signal the end of experimental investigation of short distances by high energy scattering. Black hole production might also be observable in very high energy cosmic ray neutrino events.
     
  7. Feb 7, 2004 #6

    wolram

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    this site gives a good overview.

    http://www.csmonitor.com/2003/0523/p25s02-stss.html

    Amazingly, scientists are becoming increasingly confident that they will be able to create black holes on demand, in quantity, using the new atom-smashers due to come online in the next five years. Some estimates suggest that the new Large Hadron Collider (LHC) at the European Center for Nuclear Research (CERN -the acronym is in French) will be able to create an average of one black hole each second. LHC will bombard protons and antiprotons together with such a force that the collision will create temperatures and energy densities not seen since the first trillionth of a second after the Big Bang. This should be enough to pop off numerous tiny black holes, with masses of just a few hundred protons. Black holes of this size will evaporate almost instantly, their existence detectable only by dying bursts of Hawking radiation.
     
  8. Feb 7, 2004 #7

    Stingray

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    Ahem... Some high energy physicists will say anything just to fill up their talks. These calculations depend on some very very speculative things.

    People also say supersymmetry might be found in the next experiments. In reality, accelerators would have to be improved by 15 orders of magnitude or so before supersymmetry could actually be ruled out. People just hope a positive detection will occur now even though there's no good reason to expect it (as far as I'm aware). Its the same idea with black holes in accelerators. That's probably even more shaky actually.
     
  9. Feb 7, 2004 #8

    Stingray

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    As to the original question, it is not possible to create a macroscopically sized black hole on earth, and it never will be. Even if you compressed the entire earth into a black hole, it would still only be about 1 cm across.

    It might one day be possible to create a black hole with macroscopic mass (not size), but its not conceivable right now. We can't even think of creating the much less exotic state of matter in neutron stars for example (essentially a 10 km wide atomic nucleus).

    The quantum black holes wolram has reffered to are our best bet for "real" black holes.

    A much more reasonable proposal involves certain exotic (but easily produceable) states of matter which mathematically mimic black holes in certain situations. These are sometimes called sonic or acoustic black holes.

    The idea is that light gets slowed down when traveling though a medium, so take a fluid, and make it spin faster than the local speed of light. Light will be trapped similarly to how it is in a black hole. Analogies of Hawking radiation etc are also expected to exist. These experiments should be working within a year or two I think.
     
  10. Feb 8, 2004 #9

    wolram

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    quote stingray.

    A much more reasonable proposal involves certain exotic (but easily produceable) states of matter which mathematically mimic black holes in certain situations. These are sometimes called sonic or acoustic black holes.
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    could you expand on this please? it is an interest of mine,
    how closely would the artificial BH match the real thing?
    how long could they be maintained?
    what exotic matter is used?
     
  11. Feb 8, 2004 #10

    Stingray

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    People usually talk about doing this with Bose-Einstein condensates because the speed of light can be made so small inside of them (a few mph in some recent experiments).

    I don't know all the details, but these things should trap light very similarly to a real black hole. There's no significant gravity in the system, so normal matter wouldn't be affected that way. I don't know how stable these systems would be, or what people hope to learn from them. Here are some links if you want to learn more:

    http://www.space.com/scienceastronomy/astronomy/desktop_blackhole_010123.html

    lots of links:
    http://www.physics.wustl.edu/~visser/Analog/
     
  12. Feb 8, 2004 #11

    wolram

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    thanks for the links STINGRAY, i have read quite a lot
    about BECs in the past a fascinating topic.
     
  13. Feb 8, 2004 #12
    I'm pretty sure that acoustic black holes don't trap light. They trap sound instead
     
  14. Feb 8, 2004 #13

    Stingray

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    I should have differentiated between acoustic and optical black holes. They are both possible, and one doesn't have to imply the other. If you get the fluid rotating faster than the sound speed, then you get an acoustic black hole. If you rotate it faster than light speed (in the fluid), you get an optical one.
     
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