Abstract
The folk questions in Lorentzian Geometry which concerns the smoothness of time functions and slicings by Cauchy hypersurfaces, are solved by giving simple proofs of: (a) any globally hyperbolic spacetime (M, g) admits a smooth time function whose levels are spacelike Cauchy hyperfurfaces and, thus, also a smooth global splitting if a spacetime M admits a (continuous) time function t then it admits a smooth (time) function with timelike gradient on all M.
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Beem, J.K., Ehrlich, P.E., Easley, K.L.: Global Lorentzian Geometry. Monographs Textbooks Pure Appl. Math. 202, New York: Dekker Inc., 1996
Bernal, A. N., Sánchez, M.: On Smooth Cauchy Hypersurfaces and Geroch’s Splitting Theorem. Commun. Math. Phys. 243, 461–470 (2003)
Geroch, R.: Domain of dependence. J. Math. Phys. 11, 437–449 (1970)
Hawking, S.W.: The existence of Cosmic Time Functions. Proc. Roy. Soc. London, Series A 308, 433–435 (1969)
Hawking, S.W., Ellis, G.F.R.: The large scale structure of space-time. Cambridge Monographs on Mathematical Physics, No. 1. London-NewYork: Cambridge University Press, 1973
Sachs, R.K., Wu, H.: General Relativity and Cosmology. Bull. Amer. Math. Soc. 83(6), 1101–1164 (1977)
Sánchez, M.: Causal hierarchy of spacetimes, temporal functions and smoothness of Geroch’s splitting. A revision. In: Proceedings of the 13th School of Differential Geometry, Sao Paulo, Brazil, 2004 (to appear in Matematica Contemporanea). Available at http://arxiv.org/list/gr-qc/0411143, 2004
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Communicated by G.W. Gibbons
The second-named author has been partially supported by a MCyT-FEDER Grant, MTM2004-04934-C04-01.
To Professor P.E. Ehrlich, wishing him a continued recovery and good health
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Bernal, A., Sánchez, M. Smoothness of Time Functions and the Metric Splitting of Globally Hyperbolic Spacetimes. Commun. Math. Phys. 257, 43–50 (2005). https://doi.org/10.1007/s00220-005-1346-1
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DOI: https://doi.org/10.1007/s00220-005-1346-1