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Lookup NU author(s): Dr Angela White
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Within the framework of either Euclidean ( functional integral) quantum gravity or canonical general relativity the signature of the manifold is a priori unconstrained. Furthermore, recent developments in the emergent spacetime programme have led to a physically feasible implementation of ( analogue) signature change events. This suggests that it is time to revisit the sometimes controversial topic of signature change in general relativity. Specifically, we shall focus on the behaviour of a quantum field defined on amanifold containing regions of different signature. We emphasize that regardless of the underlying classical theory, there are severe problems associated with any quantum field theory residing on a signature-changing background. ( Such as the production of what is naively an infinite number of particles, with an infinite energy density.) We show how the problem of quantum fields exposed to finite regions of Euclidean-signature (Riemannian) geometry has similarities with the quantum barrier penetration problem. Finally we raise the question as to whether signature change transitions could be fully understood and dynamically generated within ( modified) classical general relativity, or whether they require the knowledge of a theory of quantum gravity.
Author(s): White A, Weinfurtner S, Visser M
Publication type: Article
Publication status: Published
Journal: Classical and Quantum Gravity
Year: 2010
Volume: 27
Issue: 4
Print publication date: 25/01/2010
ISSN (print): 0264-9381
ISSN (electronic): 1361-6382
Publisher: Institute of Physics Publishing Ltd.
URL: http://dx.doi.org/10.1088/0264-9381/27/4/045007
DOI: 10.1088/0264-9381/27/4/045007
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