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Sonic black hole

sonic black hole, how to make a sonic black hole
A sonic black hole, sometimes called a dumb hole, is a phenomenon in which phonons sound perturbations are unable to escape from a fluid that is flowing more quickly than the local speed of sound They are called sonic, or acoustic, black holes because these trapped phonons are analogous to light in astrophysical gravitational black holes Physicists are interested in them because they have many properties similar to astrophysical black holes and, in particular, emit a phononic version of Hawking radiation[1][2] The border of a sonic black hole, at which the flow speed changes from being greater than the speed of sound to less than the speed of sound, is called the event horizon At this point the frequency of phonons approaches zero[citation needed]

Sonic black holes are possible because phonons in perfect fluids exhibit the same properties of motion as fields, such as gravity, in space and time[1] For this reason, a system in which a sonic black hole can be created is called a gravity analogue Nearly any fluid can be used to create an acoustic event horizon, but the viscosity of most fluids creates random motion[citation needed] that makes features like Hawking radiation nearly impossible to detect The complexity of such a system would make it very difficult to gain any knowledge about such features even if they could be detected[3] Many nearly perfect fluids have been suggested for use in creating sonic black holes, such as superfluid helium, one–dimensional degenerate Fermi gases, and Bose–Einstein condensate Gravity analogues other than phonons in a fluid, such as slow light and a system of ions, have also been proposed for studying black hole analogues[4] The fact that so many systems mimic gravity is sometimes used as evidence for the theory of emergent gravity, which could help reconcile relativity and quantum mechanics[5]

Acoustic black holes were first theorized to be useful by William Unruh in 1981[6] However, the first black hole analogue was not created in a laboratory until 2009 It was created in a rubidium Bose–Einstein condensate using a technique called density inversion This technique creates a flow by repelling the condensate with a potential minimum The surface gravity and temperature of the sonic black hole were measured, but no attempt was made to detect Hawking radiation However, the scientists who created it predicted that the experiment was suitable for detection and suggested a method by which it might be done by lasing the phonons[7] In 2014, self-amplifying Hawking radiation was observed in an analogue black-hole laser by the same researchers[2]

See also

  • Quantum gravity
  • Analog models of gravity
  • Black hole
  • Acoustic metric
  • Optical black hole

Notes

  1. ^ a b M Visser, “Acoustic black holes: Horizons, ergospheres, and Hawking radiation,” Classical and Quantum Gravity 15, 1767 1998 arXiv:gr-qc/9712010
  2. ^ a b J Steinhauer, "Observation of self-amplifying Hawking radiation in an analogue black-hole laser" Nat Phys doi:101038/nphys3104 2014
  3. ^ G Jannes, “Emergent gravity: the BEC paradigm,” PhD thesis, Department of Theoretical Physics, Complutense University of Madrid, page 34, Arxiv preprint arXiv:09072839 2009
  4. ^ B Horstmann, R Schützhold, B Reznik, S Fagnocchi, and J I Cirac, “Measurement of Hawking Radiation with Ions in the Quantum Regime,” Arxiv preprint arXiv:10083494, 2010
  5. ^ G Jannes, “Emergent gravity: the BEC paradigm,” PhD thesis, Department of Theoretical Physics, Complutense University of Madrid, page 12, Arxiv preprint arXiv:09072839 2009
  6. ^ W G Unruh, “Experimental black hole evaporation,” Phys Rev Lett 46, 1351 1981
  7. ^ O Lahav, A Itah, A Blumkin, C Gordon & J Steinhauer, “A sonic black hole in a density-inverted Bose–Einstein condensate” Arxiv preprint arXiv:09061337 2009

External links

  • Top 100 Stories of 2009 #79: Sonic Black Hole Created in Lab, Discover magazine, from the January-February 2010 special issue; published online December 22, 2009
  • Ars Technica: A potential solution to the black hole information loss paradox
  • "Analogue Gravity", a detailed mathematical analysis with diagrams

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Sonic black hole


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    Sonic black hole beatiful post thanks!

    29.10.2014


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