Title:	Causal continuity in degenerate spacetimes
Authors:	Borde, A. Dowker, H.F. Garcia, R.S. Sorkin, Rafael D. Surya, Sumati
Issue Date:	Nov-1999
Publisher:	Institute of Physics
Citation:	Classical and Quantum Gravity, 1999, Vol.16, Issue 11, p 3457-3481
Abstract:	A change of spatial topology in a causal, compact spacetime cannot occur when the metric is globally Lorentzian. On any cobordism manifold, however, one can construct from a Morse function f and an auxiliary Riemannian metric hµicons/Journals/Common/nu" ALT="nu" ALIGN="TOP"/> a causal metric gµicons/Journals/Common/nu" ALT="nu" ALIGN="TOP"/> which is Lorentzian almost everywhere except that it degenerates to zero at each critical point of f. We investigate causal structure in the neighbourhood of such a degeneracy, when the auxiliary Riemannian metric is taken to be Cartesian flat in appropriate coordinates. For these geometries, we verify the conjecture that causal discontinuity occurs if and only if the Morse index is 1 or n - 1.
Description:	Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)
URI:	http://hdl.handle.net/2289/4550
ISSN:	0264-9381 1361-6382
Alternative Location:	http://arxiv.org/abs/gr-qc/9901063 http://dx.doi.org/ 10.1088/0264-9381/16/11/303 http://adsabs.harvard.edu/abs/1999CQGra..16.3457B
Copyright:	1999, Institute of Physics
Appears in Collections:	Research Papers (TP)

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