Black hole analogue

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A black hole analog is a model introduced by William Unruh in 1981 that is supposed to map the processes in a black hole in the form of an analog . In particular, the aim is to enable research into a phenomenon which, due to its properties, cannot be directly observed (namely “black”). The black hole analogue is a special case of the search for analogues of gravitation in other media, which was started by Gordon in 1923 and mainly looks at electromagnetic and acoustic systems.

Simple example

The following simplified (and therefore not entirely applicable) example may serve as an illustration: In a bathtub, fish are released that can swim at a maximum speed of km / h. Now the stopper is pulled so that a vortex is created at the drain, which allows the water to flow away at a maximum speed of km / h. The flow rate decreases with the distance from the drain. If now is higher than , fish that come too close to the drain can no longer escape the suction because they swim slower than the vortex moves and are washed out. The limit at which the outflow speed equals the maximum swimming speed of the fish would be analogous to the event horizon of a black hole. Fish that cross this limit have no way of escaping.

Acoustic black hole analog

Unruh has designed an acoustic analogue of the black hole. There should be different flow velocities in liquids, which are spatially separated either faster or slower than the speed of sound . The limit would again correspond to the event horizon. Noises that arise in the area of ​​higher speed would therefore not be audible in the other area. Unruh called his model the Sonic black hole . A uniform term has not yet established itself in German, occasionally speaking of mute holes and their counterparts, the pigeon holes .

In 2000 it was proposed to use the newly discovered and experimentally very easily controllable Bose-Einstein condensates (BEC) as the basis for black hole analogues. In June 2009, scientists at the Technion in Haifa succeeded in producing such an analogue in a rubidium -BEC instead of in water. The aim was to detect the so-called Hawking radiation , which initially did not succeed. Follow-up experiments in 2014 and 2016 provided stronger evidence for Hawking radiation, but the interpretation of the results is controversial.

Optical black hole analog

In 2008, the German physicist Ulf Leonhardt presented a model of an optical black hole analog. With the help of optical fibers, he carried out experiments in which analogues of Hawking radiation were also observed.

Web links

Individual evidence

  1. ^ Matt Visser: Bibliography: Analog models of General Relativity. November 28, 2000, accessed February 25, 2018 .
  2. ↑ Luca Bombelli: Black Hole Analogs and Mimickers. University of Mississippi, August 31, 2017, accessed February 25, 2018 .
  3. ↑ This is for illustration purposes only, of course the fish can escape by swimming across the flow velocity.
  4. ^ WG Unruh: Experimental black hole evaporation . In: Phys. Rev. Lett. tape 46 , 1981, pp. 1351 . , bibcode : 1981PhRvL..46.1351U
  5. ↑ Corresponding to the white hole in astrophysics.
  6. ↑ LJ Garay, JR Anglin, JI Cirac, P. Zoller: Sonic analog of gravitational black holes in Bose-Einstein condensates . In: Phys. Rev. Lett. tape 85 , 2000, pp. 4643–4647 , doi : 10.1103 / PhysRevLett.85.4643 , arxiv : gr-qc / 0002015 .
  7. ↑ Oren Lahav, Amir Itah, Alex Blumkin, Carmit Gordon, Shahar Rinott, Alona Zayats, Jeff Steinhauer: Realization of a sonic black hole analogue in a Bose-Einstein condensate . In: Phys.Rev.Lett. tape 105 , 2010, p. 240401 , doi : 10.1103 / PhysRevLett.105.240401 , arxiv : 0906.1337 .
  8. ^ Sonic Black Hole Traps Sound Waves . ( Memento of May 7, 2012 on the Internet Archive ) Discovery.com, June 17, 2009; a more extensive presentation in English.
  9. ↑ Jeff Steinhauer: Observation of self-amplifying Hawking radiation in an analogue black-hole laser . In: Nature Physics . tape 10 , 2014, p. 864-869 , doi : 10.1038 / nphys3104 .
  10. ↑ Jeff Steinhauer: Observation of quantum Hawking radiation and its entanglement in an analogue black hole . In: Nature Physics . tape 12 , 2016, p. 959-965 , doi : 10.1038 / nphys3863 , arxiv : 1510.00621 .
  11. ↑ Davide Castelvecchi: Artificial black hole creates its own version of Hawking radiation . In: Nature . tape 536 , August 15, 2016, p. 258-259 , doi : 10.1038 / 536258a .
  12. ^ W. Unruh: Experimental black hole evaporation . In: Physics Today . September 9, 2017, doi : 10.1063 / PT.5.2047 (English).
  13. ↑ Review: Ulf Leonhardt: Questioning the recent observation of quantum Hawking radiation . arxiv : 1609.03803 . and Answer: Jeff Steinhauer: Response to version 2 of the note concerning the observation of quantum Hawking radiation and its entanglement in an analogue black hole . arxiv : 1609.09017 .