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Geon (physics)

December 28, 2022

In theoretical general relativity, a geon is a nonsingular electromagnetic or gravitational wave which is held together in a confined region by the gravitational attraction of its own field energy. They were first investigated theoretically in 1955 by J. A. Wheeler, who coined the term as a contraction of "gravitational electromagnetic entity".[1]

Overview

Since general relativity is a classical field theory, Wheeler's concept of a geon does not treat them as quantum-mechanical entities, and this generally remains true today.[clarification needed] Nonetheless, Wheeler speculated that there might be a relationship between geons and elementary particles. This idea continues to attract some attention among physicists, but in the absence of a viable theory of quantum gravity, the accuracy of this speculative idea cannot be tested.

Wheeler did not present explicit geon solutions to the vacuum Einstein field equation, a gap which was partially filled by Brill and Hartle in 1964 by the Brill–Hartle geon.[2] In 1997, Anderson and Brill gave a rigorous proof that geon solutions of the vacuum Einstein equation exist, though they are not given in a simple closed form.[3]

A major outstanding question regarding geons is whether they are stable, or must decay over time as the energy of the wave gradually "leaks" away. This question has not yet been definitively answered, but the consensus seems to be that they probably cannot be stable.[4] This would lay to rest Wheeler's initial hope that a geon might serve as a classical model for stable elementary particles. However, this would not rule out the possibility that geons are stabilized by quantum effects.[5] In fact, a quantum generalization of the gravitational geon using low-energy quantum gravity shows that geons are stable systems even when quantum effects are turned on.[6] The quantum geon (called "graviball") is described as gravitons bound by their gravitational self-interaction. Since geons (classical or quantum) have a mass but are electromagnetically neutral, they are possible candidates for dark matter.

See also

References

  1. ^ Wheeler, J. A. (January 1955). "Geons". Physical Review. 97 (2): 511–536. Bibcode:1955PhRv...97..511W. doi:10.1103/PhysRev.97.511.
  2. ^ Brill, D. R.; Hartle, J. B. (1964). "Method of the Self-Consistent Field in General Relativity and its Application to the Gravitational Geon". Physical Review. 135 (1B): B271. Bibcode:1964PhRv..135..271B. doi:10.1103/PhysRev.135.B271.
  3. ^ Anderson, Paul R.; Brill, Dieter R. (1997). "Gravitational Geons Revisited". Physical Review D. 56 (8): 4824–4833. arXiv:gr-qc/9610074. Bibcode:1997PhRvD..56.4824A. doi:10.1103/PhysRevD.56.4824. S2CID 119372143..
  4. ^ Perry, G. P.; Cooperstock, F. I. (1999). "Stability of Gravitational and Electromagnetic Geons". Classical and Quantum Gravity. 16 (6): 1889–1916. arXiv:gr-qc/9810045. Bibcode:1999CQGra..16.1889P. doi:10.1088/0264-9381/16/6/321. S2CID 18207509..
  5. ^ Klimets, A.P. Philosophy Documentation Center, Western University-Canada, 2017, pp.13-23
  6. ^ Guiot, B; Borquez, A.; Deur, A.; Werner, K. (2020). "Graviballs and Dark Matter". JHEP. 2020 (11): 159. arXiv:2006.02534. Bibcode:2020JHEP...11..159G. doi:10.1007/JHEP11(2020)159. S2CID 219303406..

Further reading

December 28, 2022
geon, physics, theoretical, general, relativity, geon, nonsingular, electromagnetic, gravitational, wave, which, held, together, confined, region, gravitational, attraction, field, energy, they, were, first, investigated, theoretically, 1955, wheeler, coined, . In theoretical general relativity a geon is a nonsingular electromagnetic or gravitational wave which is held together in a confined region by the gravitational attraction of its own field energy They were first investigated theoretically in 1955 by J A Wheeler who coined the term as a contraction of gravitational electromagnetic entity 1 Contents 1 Overview 2 See also 3 References 4 Further readingOverview EditSince general relativity is a classical field theory Wheeler s concept of a geon does not treat them as quantum mechanical entities and this generally remains true today clarification needed Nonetheless Wheeler speculated that there might be a relationship between geons and elementary particles This idea continues to attract some attention among physicists but in the absence of a viable theory of quantum gravity the accuracy of this speculative idea cannot be tested Wheeler did not present explicit geon solutions to the vacuum Einstein field equation a gap which was partially filled by Brill and Hartle in 1964 by the Brill Hartle geon 2 In 1997 Anderson and Brill gave a rigorous proof that geon solutions of the vacuum Einstein equation exist though they are not given in a simple closed form 3 A major outstanding question regarding geons is whether they are stable or must decay over time as the energy of the wave gradually leaks away This question has not yet been definitively answered but the consensus seems to be that they probably cannot be stable 4 This would lay to rest Wheeler s initial hope that a geon might serve as a classical model for stable elementary particles However this would not rule out the possibility that geons are stabilized by quantum effects 5 In fact a quantum generalization of the gravitational geon using low energy quantum gravity shows that geons are stable systems even when quantum effects are turned on 6 The quantum geon called graviball is described as gravitons bound by their gravitational self interaction Since geons classical or quantum have a mass but are electromagnetically neutral they are possible candidates for dark matter See also EditBlack hole electron Edwin Power Geometrodynamics Kugelblitz Quantum foamReferences Edit Wheeler J A January 1955 Geons Physical Review 97 2 511 536 Bibcode 1955PhRv 97 511W doi 10 1103 PhysRev 97 511 Brill D R Hartle J B 1964 Method of the Self Consistent Field in General Relativity and its Application to the Gravitational Geon Physical Review 135 1B B271 Bibcode 1964PhRv 135 271B doi 10 1103 PhysRev 135 B271 Anderson Paul R Brill Dieter R 1997 Gravitational Geons Revisited Physical Review D 56 8 4824 4833 arXiv gr qc 9610074 Bibcode 1997PhRvD 56 4824A doi 10 1103 PhysRevD 56 4824 S2CID 119372143 Perry G P Cooperstock F I 1999 Stability of Gravitational and Electromagnetic Geons Classical and Quantum Gravity 16 6 1889 1916 arXiv gr qc 9810045 Bibcode 1999CQGra 16 1889P doi 10 1088 0264 9381 16 6 321 S2CID 18207509 Klimets A P Philosophy Documentation Center Western University Canada 2017 pp 13 23 Guiot B Borquez A Deur A Werner K 2020 Graviballs and Dark Matter JHEP 2020 11 159 arXiv 2006 02534 Bibcode 2020JHEP 11 159G doi 10 1007 JHEP11 2020 159 S2CID 219303406 Further reading EditLouko Jorma Mann Robert B Marolf Donald 2005 Geons with spin and charge Classical and Quantum Gravity 22 7 1451 1468 arXiv gr qc 0412012 Bibcode 2005CQGra 22 1451L doi 10 1088 0264 9381 22 7 016 S2CID 119177143 Retrieved from https en wikipedia org w index php title Geon physics amp oldid 1100181680, wikipedia, wiki, book, books, library,

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