Abstract
Causal sets (or causets) are a particular class of partially ordered sets, which are proposed as basic models of discrete space-time, specially in the field of quantum gravity. In this context, we show the existence of temporal foliations for any causal set, or more generally, for a causal space. Moreover, we show that (order-preserving) automorphisms of a large class of infinite causal sets fall into two classes 1) Automorphisms of spacelike hypersurfaces in some given foliation (i.e. spacelike automorphisms), or 2) Translations in time. More generally, we show that for any automorphism \(\Phi \) of a generic causal set \({\mathcal {C}}\), there exists a partition of \({\mathcal {C}}\) into finitely many subcausets, on each of which (1) or (2) above hold. These subcausets can be assumed connected if, in addition, there are enough distinct orbits under \(\Phi \).
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References
Bombelli, L., Lee, J., Meyer, D., Sorkin, R.D.: Spacetime as a causal set. Phys. Rev. Lett. 59, 521 (1987)
Bernal, A.N., Sánchez, M.: On smooth Cauchy hypersurfaces and Geroch’s splitting theorem. Commun. Math. Phys. 243(3), 461470 (2003)
Bernal, A.N., Sánchez, M.: Further results on the smoothability of Cauchy hypersurfaces and Cauchy time functions. Lett. Math. Phys. 77, 183–197 (2006)
Carlip, S.: Dimensional reduction in causal set gravity. Class. Quantum Gravity. 32(23), 232001 (2015)
Droste, M.: Universal homogeneous causal set. J. Math. Phys. 46, 122503 (2005)
Dilworth, R.P.: A decomposition theorem for partially ordered sets. Ann. Math. 51(1), 161166 (1950). https://doi.org/10.2307/1969503
Dribus, B.: Discrete Causal Theory, Emergent Spacetime and the Causal Metric Hypothesis. Springer, New York (2017)
Geroch, R.: Domain of dependence. J. Math. Phys. 11, 437449 (1970)
Kronheimer, E.H., Penrose, R.: On the structure of causal spaces. Proc. Cambridge Philos. Soc 63(2), 481–501 (1967)
Major, S., Rideout, D., Surya, S.: On recovering continuum topology from a causal set. J. Math. Phys. 48, 032501 (2007)
Rideout, D., Wallden, P.: Emergent continuum spacetime from a random, discrete, partial order. J. Phys. 189, 1 (2009)
Rideout, D., Wallden, P.: Spacelike distance from discrete causal order. Class. Quantum Grav. 26, 155013 (2009)
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We wish to thank Aron Wall for attracting our attention to some issues with a previous version of the manuscript.
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Bleybel, A., Zaiour, A. A General Theorem on Temporal Foliations of Causal Sets. Found Phys 48, 456–478 (2018). https://doi.org/10.1007/s10701-018-0157-0
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DOI: https://doi.org/10.1007/s10701-018-0157-0