Причинные множества (Hjncnuudy buk'yvmfg)

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Причинные множества — направление исследований в квантовой гравитации, основанное на математической гипотезе о дискретной структуре пространства-времени и о частичной упорядоченности его точек, физически означающей причинно-следственные связи[англ.] между событиями в них с сохранением лоренцевской инвариантности.

В теории причинных множеств важную роль играет теорема[1] Дэвида Маламента (David Malament[англ.]), которая гласит, что если существует биективное отображение между двумя различающими прошлое и будущее[англ.] областями пространства-времени, которое сохраняет их причинную структуру, то это отображение является конформно изоморфным. Конформный множитель, который остается неопределенным, связан с объемом областей в пространстве-времени. Его можно найти, указав элемент объема для каждой точки пространства-времени. Общий объем области пространства-времени затем может быть найден путем подсчета количества точек в этой области.

Определение

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Причинным множеством называется множество с отношением частичной упорядоченности , обладающее свойствами:

  • Рефлексивность: Для всех , выполняется .
  • Антисимметричность: Для всех из справедливости и следует .
  • Транзитивность: Для всех , из справедливости и следует .
  • Локальная конечность[англ.]: Для всех , выполняется .

Если и , то используют обозначение .

Множество представляет набор событий пространства-времени, а отношение порядка представляет причинно-следственную связь между событиями (аналогичную идею в лоренцевом многообразии см. причинно-следственные связи[англ.]).

Хотя в этом определении используется рефлексивное соглашение, мы могли бы выбрать нерефлексивное соглашение, в котором отношение порядка нерефлексивно.

Причинная структура[англ.] лоренцева многообразия (без замкнутой причинно-следственной кривой[англ.]) удовлетворяет первым трем условиям. Это условие локальной конечности, которое вводит дискретность пространства-времени.

Примечания

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  1. Malament, David B. (July 1977). "The class of continuous timelike curves determines the topology of spacetime" (PDF). Journal of Mathematical Physics. 18 (7): 1399—1404. Bibcode:1977JMP....18.1399M. doi:10.1063/1.523436. Архивировано (PDF) 14 декабря 2021. Дата обращения: 19 сентября 2021.

Дальнейшее чтение

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Введения и обзоры
Основы теории
  • L. Bombelli, J. Lee, D. Meyer, R.D. Sorkin, Spacetime as a causal set, Phys. Rev. Lett. 59:521-524 (1987); (Introduction, Foundations)
  • C. Moore, Comment on «Space-time as a causal set», Phys. Rev. Lett. 60, 655 (1988); (Foundations)
  • L. Bombelli, J. Lee, D. Meyer, R.D. Sorkin, Bombelli et al. Reply, Phys. Rev. Lett. 60, 656 (1988); (Foundations)
  • A. Einstein, Letter to H.S. Joachim, August 14, 1954; Item 13-453 cited in J. Stachel, «Einstein and the Quantum: Fifty Years of Struggle», in From Quarks to Quasars, Philosophical Problems of Modern Physics, edited by R.G. Colodny (U. Pittsburgh Press, 1986), pages 380—381; (Historical)
  • D. Finkelstein, Space-time code, Phys. Rev. 184:1261 (1969); (Foundations)
  • D. Finkelstein, «Superconducting» Causal Nets, Int. J. Th. Phys 27:473(1988); (Foundations)
  • G. Hemion, A quantum theory of space and time; Found. Phys. 10 (1980), p. 819 (Similar proposal)
  • J. Myrheim, Statistical geometry, CERN preprint TH-2538 (1978); (Foundations, Historical)
  • B. Riemann, Über die Hypothesen, welche der Geometrie zu Grunde liegen, The Collected Works of B. Riemann (Dover NY 1953); ; (Historical)
  • R.D. Sorkin; A Finitary Substitute for Continuous Topology, Int. J. Theor. Phys. 30 7: 923—947 (1991); (Foundational)
  • R.D. Sorkin, Does a Discrete Order underly Spacetime and its Metric?, Proceedings of the Third Canadian Conference on General Relativity and Relativistic Astrophysics, (Victoria, Canada, May, 1989), edited by A. Coley, F. Cooperstock, B.Tupper, pp. 82-86, (World Scientific, 1990); (Introduction)
  • R.D. Sorkin, First Steps with Causal Sets Архивировано 30 сентября 2013 года., General Relativity and Gravitational Physics, (Proceedings of the Ninth Italian Conference of the same name, held Capri, Italy, September, 1990), 68-90, (World Scientific, Singapore), (1991), R. Cianci, R. de Ritis, M. Francaviglia, G. Marmo, C. Rubano, P. Scudellaro (eds.); (Introduction)
  • R.D. Sorkin, Spacetime and Causal Sets Архивировано 30 сентября 2013 года., Relativity and Gravitation: Classical and Quantum, (Proceedings of the SILARG VII Conference, held Cocoyoc, Mexico, December, 1990), pages 150—173, (World Scientific, Singapore, 1991), J.C. D’Olivo, E. Nahmad-Achar, M.Rosenbaum, M.P. Ryan, L.F. Urrutia and F. Zertuche (eds.); (Introduction)
  • R.D. Sorkin, Forks in the Road, on the Way to Quantum Gravity, Talk given at the conference entitled «Directions in General Relativity», held at College Park, Maryland, May, 1993, Int. J. Th. Phys. 36: 2759—2781 (1997); arXiv:gr-qc/9706002; (Philosophical, Introduction)
  • G.'t Hooft, Quantum gravity: a fundamental problem and some radical ideas, Recent Developments in Gravitation (Proceedings of the 1978 Cargese Summer Institute) edited by M. Levy and S. Deser (Plenum, 1979); (Introduction, Foundations, Historical)
  • E.C. Zeeman, Causality Implies the Lorentz Group, J. Math. Phys. 5: 490—493; (Historical, Foundations)
Диссертации
Обсуждения
Теория многообразий
  • L. Bombelli, D.A. Meyer; The origin of Lorentzian geometry; Phys. Lett. A 141:226-228 (1989); (Manifoldness)
  • L. Bombelli, R.D. Sorkin, When are Two Lorentzian Metrics close?, General Relativity and Gravitation, proceedings of the 12th International Conference on General Relativity and Gravitation, held July 2-8, 1989, in Boulder, Colorado, USA, under the auspices of the International Society on General Relativity and Gravitation, 1989, p. 220; (Closeness of Lorentzian manifolds)
  • L. Bombelli, Causal sets and the closeness of Lorentzian manifolds, Relativity in General: proceedings of the Relativity Meeting "93, held September 7-10, 1993, in Salas, Asturias, Spain. Edited by J. Diaz Alonso, M. Lorente Paramo. ISBN 2-86332-168-4. Published by Editions Frontieres, 91192 Gif-sur-Yvette Cedex, France, 1994, p. 249; (Closeness of Lorentzian manifolds)
  • L. Bombelli, Statistical Lorentzian geometry and the closeness of Lorentzian manifolds, J. Math. Phys.41:6944-6958 (2000); arXiv:gr-qc/0002053 (Closeness of Lorentzian manifolds, Manifoldness)
  • A.R. Daughton, An investigation of the symmetric case of when causal sets can embed into manifolds, Class. Quantum Grav.15(11):3427-3434 (Nov., 1998) (Manifoldness)
  • J. Henson, Constructing an interval of Minkowski space from a causal set, Class. Quantum Grav. 23 (2006) L29-L35; arXiv:gr-qc/0601069; (Continuum limit, Sprinkling)
  • S. Major, D.P. Rideout, S. Surya, On Recovering Continuum Topology from a Causal Set, J.Math.Phys.48:032501,2007; arXiv:gr-qc/0604124 (Continuum Topology)
  • S. Major, D.P. Rideout, S. Surya; Spatial Hypersurfaces in Causal Set Cosmology; Class. Quantum Grav. 23 (2006) 4743-4752; arXiv:gr-qc/0506133v2; (Observables, Continuum topology)
  • S. Major, D.P. Rideout, S. Surya, Stable Homology as an Indicator of Manifoldlikeness in Causal Set Theory, arXiv:0902.0434 (Continuum topology and homology)
  • D.A. Meyer, The Dimension of Causal Sets I: Minkowski dimension, Syracuse University preprint (1988); (Dimension theory)
  • D.A. Meyer, The Dimension of Causal Sets II: Hausdorff dimension, Syracuse University preprint (1988); (Dimension theory)
  • D.A. Meyer, Spherical containment and the Minkowski dimension of partial orders, Order 10: 227—237 (1993); (Dimension theory)
  • J. Noldus, A new topology on the space of Lorentzian metrics on a fixed manifold, Class. Quant. Grav 19: 6075-6107 (2002); (Closeness of Lorentzian manifolds)
  • J. Noldus, A Lorentzian Gromov-Hausdorff notion of distance, Class. Quantum Grav. 21, 839—850, (2004); (Closeness of Lorentzian manifolds)
  • D.D. Reid, Manifold dimension of a causal set: Tests in conformally flat spacetimes, Phys. Rev. D67 (2003) 024034; arXiv:gr-qc/0207103v2 (Dimension theory)
  • S. Surya, Causal Set Topology; arXiv:0712.1648
Геометрия
Вычисление космологической постоянной
  • M. Ahmed, S. Dodelson, P.B. Greene, R.D. Sorkin, Everpresent lambda; Phys. Rev. D69, 103523, (2004) arXiv:astro-ph/0209274v1; (Cosmological Constant)
  • Y. Jack Ng and H. van Dam, A small but nonzero cosmological constant; Int. J. Mod. Phys D. 10 : 49 (2001) arXiv:hep-th/9911102v3; (PreObservation Cosmological Constant)
  • Y. Kuznetsov, On cosmological constant in Causal Set theory; arXiv:0706.0041
  • R.D. Sorkin, A Modified Sum-Over-Histories for Gravity; reported in Highlights in gravitation and cosmology: Proceedings of the International Conference on Gravitation and Cosmology, Goa, India, 14-19 December 1987, edited by B. R. Iyer, Ajit Kembhavi, Jayant V. Narlikar, and C. V. Vishveshwara, see pages 184—186 in the article by D. Brill and L. Smolin: «Workshop on quantum gravity and new directions», pp 183—191 (Cambridge University Press, Cambridge, 1988); (PreObservation Cosmological Constant)
  • R.D. Sorkin; On the Role of Time in the Sum-over-histories Framework for Gravity, paper presented to the conference on The History of Modern Gauge Theories, held Logan, Utah, July 1987; Int. J. Theor. Phys. 33 : 523—534 (1994); (PreObservation Cosmological Constant)
  • R.D. Sorkin, First Steps with Causal Sets Архивировано 30 сентября 2013 года., in R. Cianci, R. de Ritis, M. Francaviglia, G. Marmo, C. Rubano, P. Scudellaro (eds.), General Relativity and Gravitational Physics (Proceedings of the Ninth Italian Conference of the same name, held Capri, Italy, September, 1990), pp. 68-90 (World Scientific, Singapore, 1991); (PreObservation Cosmological Constant)
  • R.D. Sorkin; Forks in the Road, on the Way to Quantum Gravity, talk given at the conference entitled «Directions in General Relativity», held at College Park, Maryland, May, 1993; Int. J. Th. Phys. 36 : 2759—2781 (1997) arXiv:gr-qc/9706002; (PreObservation Cosmological Constant)
  • R.D. Sorkin, Discrete Gravity; a series of lectures to the First Workshop on Mathematical Physics and Gravitation, held Oaxtepec, Mexico, Dec. 1995 (unpublished); (PreObservation Cosmological Constant)
  • R.D. Sorkin, Big extra dimensions make Lambda too small; arXiv:gr-qc/0503057v1; (Cosmological Constant)
  • R.D. Sorkin, Is the cosmological «constant» a nonlocal quantum residue of discreteness of the causal set type?; Proceedings of the PASCOS-07 Conference, July 2007, Imperial College London; arXiv:0710.1675; (Cosmological Constant)
  • J. Zuntz, The CMB in a Causal Set Universe, arXiv:0711.2904 (CMB)
Лоренцевская инвариантность
  • L. Bombelli, J. Henson, R.D. Sorkin; Discreteness without symmetry breaking: a theorem; arXiv:gr-qc/0605006v1; (Lorentz invariance, Sprinkling)
  • F. Dowker, J. Henson, R.D. Sorkin, Quantum gravity phenomenology, Lorentz invariance and discreteness; Mod. Phys. Lett. A19, 1829—1840, (2004) arXiv:gr-qc/0311055v3; (Lorentz invariance, Phenomenology, Swerves)
  • F. Dowker, J. Henson, R.D. Sorkin, Discreteness and the transmission of light from distant sources; arXiv:1009.3058 (Coherence of light, Phenomenology)
  • J. Henson, Macroscopic observables and Lorentz violation in discrete quantum gravity; arXiv:gr-qc/0604040v1; (Lorentz invariance, Phenomenology)
  • N. Kaloper, D. Mattingly, Low energy bounds on Poincaré violation in causal set theory; Phys. Rev. D 74, 106001 (2006) arXiv:astro-ph/0607485 (Poincaré invariance, Phenomenology)
  • D. Mattingly, Causal sets and conservation laws in tests of Lorentz symmetry; Phys. Rev. D 77, 125021 (2008) arXiv:0709.0539 (Lorentz invariance, Phenomenology)
  • L. Philpott, F. Dowker, R.D. Sorkin, Energy-momentum diffusion from spacetime discreteness; arXiv:0810.5591 (Phenomenology, Swerves)
Энтропия черных дыр
  • D. Dou, Black Hole Entropy as Causal Links; Fnd. of Phys, 33 2:279-296(18) (2003); arXiv:gr-qc/0302009v1 (Black hole entropy)
  • D.P. Rideout, S. Zohren, Counting entropy in causal set quantum gravity ; arXiv:gr-qc/0612074v1; (Black hole entropy)
  • D.P. Rideout, S. Zohren, Evidence for an entropy bound from fundamentally discrete gravity; Class. Quantum Grav. 23 (2006) 6195-6213; arXiv:gr-qc/0606065v2 (Black hole entropy)
Локальность и квантовая теория поля
Динамика
  • M. Ahmed, D. Rideout, Indications of de Sitter Spacetime from Classical Sequential Growth Dynamics of Causal Sets; arXiv:0909.4771
  • A.Ash, P. McDonald, Moment Problems and the Causal Set Approach to Quantum Gravity; J.Math.Phys. 44 (2003) 1666—1678; arXiv:gr-qc/0209020
  • A.Ash, P. McDonald, Random partial orders, posts, and the causal set approach to discrete quantum gravity; J.Math.Phys. 46 (2005) 062502 (Analysis of number of posts in growth processes)
  • D.M.T. Benincasa, F. Dowker, The Scalar Curvature of a Causal Set; arXiv:1001.2725; (Scalar curvature, actions)
  • G. Brightwell; M. Luczak; Order-invariant Measures on Causal Sets; arXiv:0901.0240; (Measures on causal sets)
  • G. Brightwell; M. Luczak; Order-invariant Measures on Fixed Causal Sets; arXiv:0901.0242; (Measures on causal sets)
  • G. Brightwell, H.F. Dowker, R.S. Garcia, J. Henson, R.D. Sorkin; General covariance and the «problem of time» in a discrete cosmology; In ed. K. Bowden, Correlations:Proceedings of the ANPA 23 conference, August 16-21, 2001, Cambridge, England, pp. 1-17. Alternative Natural Philosophy Association, (2002).;arXiv:gr-qc/0202097; (Cosmology, Dynamics, Observables)
  • G. Brightwell, H.F. Dowker, R.S. Garcia, J. Henson, R.D. Sorkin; «Observables» in causal set cosmology; Phys. Rev. D67, 084031, (2003); arXiv:gr-qc/0210061; (Cosmology, Dynamics, Observables)
  • G. Brightwell, J. Henson, S. Surya; A 2D model of Causal Set Quantum Gravity: The emergence of the continuum; arXiv:0706.0375; (Quantum Dynamics, Toy Model)
  • G.Brightwell, N. Georgiou; Continuum limits for classical sequential growth models University of Bristol preprint. (Dynamics)
  • A. Criscuolo, H. Waelbroeck; Causal Set Dynamics: A Toy Model; Class. Quantum Grav.16:1817-1832 (1999); arXiv:gr-qc/9811088; (Quantum Dynamics, Toy Model)
  • F. Dowker, S. Surya; Observables in extended percolation models of causal set cosmology;Class. Quantum Grav. 23, 1381—1390 (2006); arXiv:gr-qc/0504069v1; (Cosmology, Dynamics, Observables)
  • M. Droste, Universal homogeneous causal sets, J. Math. Phys. 46, 122503 (2005); arXiv:gr-qc/0510118; (Past-finite causal sets)
  • J. Henson, D. Rideout, R.D. Sorkin, S. Surya; Onset of the Asymptotic Regime for (Uniformly Random) Finite Orders; Experimental Mathematics 26, 3:253-266 (2017); (Cosmology, Dynamics)
  • A.L. Krugly; Causal Set Dynamics and Elementary Particles; Int. J. Theo. Phys 41 1:1-37(2004);; (Quantum Dynamics)
  • X. Martin, D. O’Connor, D.P. Rideout, R.D. Sorkin; On the «renormalization» transformations induced by cycles of expansion and contraction in causal set cosmology; Phys. Rev. D 63, 084026 (2001); arXiv:gr-qc/0009063 (Cosmology, Dynamics)
  • D.A. Meyer; Spacetime Ising models; (UCSD preprint May 1993); (Quantum Dynamics)
  • D.A. Meyer; Why do clocks tick?; General Relativity and Gravitation 25 9:893-900;; (Quantum Dynamics)
  • I. Raptis; Quantum Space-Time as a Quantum Causal Set, arXiv:gr-qc/0201004v8
  • D.P. Rideout, R.D. Sorkin; A classical sequential growth dynamics for causal sets, Phys. Rev. D, 6, 024002 (2000);arXiv:gr-qc/9904062 (Cosmology, Dynamics)
  • D.P. Rideout, R.D. Sorkin; Evidence for a continuum limit in causal set dynamics Phys. Rev. D 63:104011,2001; arXiv:gr-qc/0003117(Cosmology, Dynamics)
  • R.D. Sorkin; Indications of causal set cosmology; Int. J. Theor. Ph. 39(7):1731-1736 (2000); arXiv:gr-qc/0003043; (Cosmology, Dynamics)
  • R.D. Sorkin; Relativity theory does not imply that the future already exists: a counterexample; Relativity and the Dimensionality of the World, Vesselin Petkov (ed.) (Springer 2007, in press); arXiv:gr-qc/0703098v1; (Dynamics, Philosophy)
  • M. Varadarajan, D.P. Rideout; A general solution for classical sequential growth dynamics of Causal Sets; Phys. Rev. D 73 (2006) 104021; arXiv:gr-qc/0504066v3; (Cosmology, Dynamics)
  • M.R., Khoshbin-e-Khoshnazar (2013). "Binding Energy of the Very Early Universe: Abandoning Einstein for a Discretized Three–Torus Poset.A Proposal on the Origin of Dark Energy". Gravitation and Cosmology. 19 (2): 106—113. Bibcode:2013GrCo...19..106K. doi:10.1134/s0202289313020059. S2CID 121288092.;(Dynamics, Poset)