Black hole cosmology
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The black hole cosmology (also called Schwarzschild cosmology or black hole universe) is a cosmological model in which the observable universe is the interior of a black hole. This model was originally proposed in 1972 by Raj Pathria,[1] who compared the Schwarzschild metric with the closed Friedmann–Lemaître–Robertson–Walker metric at the maximum scale factor. Subsequent studies analyzed a universe in a black hole by matching the Schwarzschild metric outside the black hole with the de Sitter space inside the black hole, on the assumption that some limiting curvature exists,[2][3][4] or with the Friedmann space.[5] The scenarios in which the universe is formed in the interior of a black hole might naturally solve the horizon problem and flatness problem in cosmology.[6]
Nikodem Popławski proposed in 2010 the first physically grounded mechanism for every black hole to avoid a gravitational singularity during gravitational collapse, undergo a non-singular gravitational bounce, and consequently create a new, expanding universe on the other side of its event horizon.[7][8] This mechanism is based on general relativity with spin and torsion, also known as the Einstein–Cartan–Sciama–Kibble theory of gravity, proposed by Élie Cartan, Dennis Sciama, and Thomas Kibble.[9][10] The existence of torsion is required for general relativity to be consistent with the conservation of the total (orbital plus spin) angular momentum of a free particle satisfying the Dirac equation in curved spacetime.[11] Fermions are the source of torsion, generating a repulsive spin-spin interaction, which prevents the formation of singularities.[12] Quantum particle production strengthens this interaction, naturally generating a finite period of exponential expansion, known as cosmic inflation.[13] A non-singular bounce also occurs for non-spherical black holes.[14]
Description
[edit]During gravitational collapse of most massive stars and centers of galaxies, a black hole forms. The matter in a black hole continues to contract. At extremely high densities, much larger than the density of nuclear matter, torsion or any other mechanism limiting curvature prevents the matter from compressing indefinitely to a singularity. Instead, the collapsing matter reaches a state with an extremely large but finite density, stops collapsing, undergoes a bounce, and starts rapidly expanding into a new space, which is equivalent to a new, expanding universe on the other side of the black hole's event horizon.
The new universe in a black hole is closed: finite but without boundaries. It can be thought of as a three-dimensional analogue of the two-dimensional surface of a sphere. The formation and evolution of such a universe is not visible for external observers in the parent universe, for whom the event horizon's formation and all subsequent processes would occur after an infinite amount of time had elapsed (because of the time dilation by gravity). A child universe is thus a separate, closed spacetime branch with its own timeline.
According to this scenario, our Universe was born as a child universe in a black hole existing in a larger parent universe. This black hole appears as the only white hole. The non-singular Big Bounce, at which the Universe had a non-zero, minimum scale factor, is regarded as the Big Bang. All universes created by black holes form the multiverse.
Variants
[edit]Limiting curvature hypothesis
[edit]Limiting curvature hypothesis, proposed by Valeri Frolov, Moisey Markov, and Viatcheslav Mukhanov in 1989, assumed the existence of an upper limit on the curvature invariants, which prevents gravitational singularities. It was used to impose the matching between the Schwarzschild metric outside a black hole and the de Sitter metric inside the black hole.
Cosmological natural selection
[edit]Lee Smolin proposed in 1992 that all final singularities bounce or tunnel to initial singularities of new universes, at which point the dimensionless parameters of the standard models of particle physics and cosmology can undergo small random changes, providing a mechanism for cosmological natural selection.[15]
Shockwave cosmology
[edit]Shockwave cosmology, proposed by Joel Smoller and Blake Temple in 2003,[16] described the Big Bang as an explosion inside a black hole, producing the expanding volume of space and matter that includes the observable universe. This black hole eventually becomes a white hole as the matter density decreases with the expansion. The acceleration of the expansion of the observable universe, normally attributed to dark energy, may be caused by an effect of the shockwave.
Universe in a black hole with torsion
[edit]The Einstein–Cartan theory has the same Lagrangian for the gravitational field as general relativity but without the condition that the affine connection be symmetric. The antisymmetric part of the affine connection, the torsion tensor, is regarded as a field (similarly to the Palatini variation of general relativity without torsion). In the presence of torsion, the energy-momentum tensor for a spinor field is not symmetric, from which it follows that the sum of the orbital and spin angular momentum (instead of the orbital part only) of a free Dirac particle is conserved, as it should be. Torsion therefore extends general relativity to matter with quantum-mechanical spin.
Fermions, described by Dirac spinor fields, are the source of torsion, generating a repulsive spin-spin interaction, which becomes strong at extremely high densities, naturally deriving a limiting curvature and preventing the formation of singularities.[17] Accordingly, a black hole becomes a non-singular Einstein–Rosen bridge (the simplest wormhole) to a new, closed universe on the other side of its event horizon.[18] Quantum particle production during expansion strengthens this interaction, increasing the mass inside a black hole by many orders of magnitude and naturally generating a finite period of cosmic inflation. The avoidance of singularities also occurs for non-spherical, rotating black holes because particle production in strong gravitational fields during contraction helps torsion to overcome the opposing effects of shear and generate the bounce.
Evidence
[edit]Any model of the observable Universe being the interior of a black hole requires that the Hubble radius of the Universe be equal to its Schwarzschild radius, which is proportional to its mass. This is indeed observed to be nearly the case, but might be a coincidence.[19]
Black holes and wormholes are different mathematical solutions of general relativity. The exteriors of both solutions with the same mass are indistinguishable for observers. The only way to test the idea that black holes create new universes is to measure the observable Universe. Inflation generated by spin and torsion is consistent with the cosmic microwave background data from the Planck satellite.[20]
A recent analysis of a sample of over 200 early galaxies showed that, around two thirds spin clockwise, whereas only half would be expected to do so. One possible explanation for this anomaly is that the Universe might be inside a rotating black hole; as all known black holes spin and this spin would manifest itself as a preferred axis in the Universe, influencing all galaxies. Alternatively, the Universe might spin slowly for some other reason, or there may be some problem with the data.[21]
See also
[edit]References
[edit]- ^ Pathria, R. K. (1972). "The universe as a black hole". Nature. 240 (5379): 298–299. Bibcode:1972Natur.240..298P. doi:10.1038/240298a0. S2CID 4282253.
- ^ Frolov, V. P.; Markov, M. A.; Mukhanov, V. F. (1989). "Through a black hole into a new universe?". Physics Letters B. 216 (3–4): 272–276. doi:10.1016/0370-2693(89)91114-3.
- ^ Frolov, V. P.; Markov, M. A.; Mukhanov, V. F. (1990). "Black holes as possible sources of closed and semiclosed worlds". Physical Review D. 41 (2): 383–394. doi:10.1103/PhysRevD.41.383.
- ^ Morgan, D. (1991). "Black holes in cutoff gravity". Physical Review D. 43 (10): 3144–3146. doi:10.1103/PhysRevD.43.3144.
- ^ Stuckey, W. M. (1994). "The observable universe inside a black hole". American Journal of Physics. 62: 788–795. doi:10.1119/1.17460.
- ^ Easson, D. A.; Brandenberger, R. H. (2001). "Universe generation from black hole interiors". Journal of High Energy Physics. 06: 024. doi:10.1088/1126-6708/2001/06/024.
- ^ Popławski, N. J. (2010). "Cosmology with torsion: An alternative to cosmic inflation". Physics Letters B. 694 (3): 181–185. arXiv:1007.0587. Bibcode:2010PhLB..694..181P. doi:10.1016/j.physletb.2010.09.056.
- ^ Popławski, N. (2023). "Chapter 13: Gravitational Collapse with Torsion and Universe in a Black Hole". In C. Bambi (ed.). Regular Black Holes: Towards a New Paradigm of Gravitational Collapse. Springer. pp. 485–499. arXiv:2307.12190. doi:10.1007/978-981-99-1596-5_13.
- ^ Kibble, T. W. B. (1961). "Lorentz invariance and the gravitational Field". Journal of Mathematical Physics. 2 (2): 212–221. Bibcode:1961JMP.....2..212K. doi:10.1063/1.1703702. ISSN 0022-2488. S2CID 54806287.
- ^ Sciama, D. W. (1964). "The physical structure of general relativity". Reviews of Modern Physics. 36 (1): 463–469. Bibcode:1964RvMP...36..463S. doi:10.1103/revmodphys.36.463. ISSN 0034-6861.
- ^ Hehl, F. W.; von der Heyde, P.; Kerlick, G. D.; Nester, J. M. (1976). "General relativity with spin and torsion: Foundations and prospects". Reviews of Modern Physics. 48 (3): 393–416. Bibcode:1976RvMP...48..393H. doi:10.1103/revmodphys.48.393. ISSN 0034-6861. S2CID 55726649.
- ^ Hehl, F. W.; von der Heyde, P.; Kerlick, G. D. (1974). "General relativity with spin and torsion and its deviations from Einstein's theory". Physical Review D. 10 (4): 1066–1069. doi:10.1103/PhysRevD.10.1066.
- ^ Popławski, N. (2016). "Universe in a black hole in Einstein-Cartan gravity". Astrophysical Journal. 832 (2): 96. arXiv:1410.3881. Bibcode:2016ApJ...832...96P. doi:10.3847/0004-637X/832/2/96. S2CID 119771613.
- ^ Popławski, N. (2021). "Gravitational collapse of a fluid with torsion into a universe in a black hole". Journal of Experimental and Theoretical Physics. 132 (3): 374–380. arXiv:2008.02136. Bibcode:2021JETP..132..374N. doi:10.1134/S1063776121030092.
- ^ Smolin, L. (1992). "Did the universe evolve?". Classical and Quantum Gravity. 9 (1): 173. doi:10.1088/0264-9381/9/1/016.
- ^ Smoller, J.; Temple, B. (2003). "Shock-wave cosmology inside a black hole". Proceedings of the National Academy of Sciences. 100 (20): 11216–11218. arXiv:astro-ph/0210105. doi:10.1073/pnas.1833875100.
- ^ Popławski, N. (2012). "Nonsingular, big-bounce cosmology from spinor-torsion coupling". Physical Review D. 85 (10): 107502. arXiv:1111.4595. Bibcode:2012PhRvD..85j7502P. doi:10.1103/PhysRevD.85.107502. S2CID 118434253.
- ^ Popławski, N. J. (2010). "Radial motion into an Einstein-Rosen bridge". Physics Letters B. 687 (2–3): 110–113. arXiv:0902.1994. Bibcode:2010PhLB..687..110P. doi:10.1016/j.physletb.2010.03.029. S2CID 5947253.
- ^ Landsberg, P. T. (1984). "Mass scales and the cosmological coincidences". Annalen der Physik. 496 (2): 88–92. Bibcode:1984AnP...496...88L. doi:10.1002/andp.19844960203.
- ^ Desai, S.; Popławski, N. J. (2016). "Non-parametric reconstruction of an inflaton potential from Einstein–Cartan–Sciama–Kibble gravity with particle production". Physics Letters B. 755: 183–189. arXiv:1510.08834. Bibcode:2016PhLB..755..183D. doi:10.1016/j.physletb.2016.02.014. S2CID 55366841.
- ^ Shamir, L. (2025). "The distribution of galaxy rotation in JWST Advanced Deep Extragalactic Survey". Monthly Notices of the Royal Astronomical Society. 538 (1): 76–91.
