High Energy Physics - Theory
[Submitted on 4 May 2018 (v1), last revised 21 Sep 2018 (this version, v2)]
Title:Inconsistencies of the New No-Boundary Proposal
View PDFAbstract:In previous works, we have demonstrated that the path integral for {\it real, Lorentzian} four-geometries in Einstein gravity yields sensible results in well-understood physical situations, but leads to uncontrolled fluctuations when the "no boundary" condition proposed by Hartle and Hawking is imposed. In order to circumvent our result, new definitions for the gravitational path integral have been sought, involving specific choices for a class of {\it complex} four-geometries to be included. In their latest proposal, Diaz Dorronsoro {\it et al.}~\cite{DiazDorronsoro:2018wro} advocate integrating the lapse over a complex circular contour enclosing the origin. In this note we show that, like their earlier proposal, this leads to mathematical and physical inconsistencies and thus cannot be regarded as a basis for quantum cosmology. We also comment on Vilenkin and Yamada's recent modification of the "tunneling" proposal, made in order to avoid the same problems. We show that it leads to the breakdown of perturbation theory in a strong coupling regime.
Submission history
From: Jean-Luc Lehners [view email][v1] Fri, 4 May 2018 05:15:13 UTC (720 KB)
[v2] Fri, 21 Sep 2018 15:39:01 UTC (727 KB)
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