Comment on `Quantum Creation of an Open Universe', by Andrei Linde

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dc.creatorHawking, S. W.
dc.creatorTurok, Neil
dc.date1998-02-25
dc.date1998-04-06
dc.date.accessioned2026-07-07T03:32:14Z
dc.date.available2026-07-07T03:32:14Z
dc.descriptionWe comment on Linde's claim that one should change the sign in the action for a Euclidean instanton in quantum cosmology, resulting in the formula $P \sim e^{+S}$ for the probability of various classical universes. There are serious problems with doing so. If one reverses the sign of the action of both the instanton and the fluctuations, the latter are unsupressed and the calculation becomes meaningless. So for a sensible result one would have to reverse the sign of the action for the background, while leaving the sign for the perturbations fixed by the usual Wick rotation. The problem with this approach is that there is no invariant way to split a given four geometry into background plus perturbations. So the prescription would have to violate general coordinate invariance. There are other indications that a sign change is problematic. With the choice $P \sim e^{+S}$ the nucleation of primordial black holes during inflation is unsuppressed, with a disastrous resulting cosmology. We regard these as compelling arguments for adhering to the usual sign given by the Wick rotation.
dc.description4 pages. Rhetoric reduced. RevTex file
dc.identifierhttps://arxiv.org/abs/gr-qc/9802062
dc.identifierhttp://arxiv.org/abs/gr-qc/9802062
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/36155
dc.subjectGeneral Relativity and Quantum Cosmology
dc.subjectAstrophysics
dc.subjectHigh Energy Physics - Phenomenology
dc.subjectHigh Energy Physics - Theory
dc.titleComment on `Quantum Creation of an Open Universe', by Andrei Linde
dc.typetext

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