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Title: Spacetime conformal fluctuations and quantum dephasing
Author: Bonifacio, Paolo
ISNI:       0000 0004 0102 6384
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2009
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We employ a stochastic approach that models spacetime fluctuations close to the Planck scale by means of a classical, randomly fluctuating metric (random gravity framework).  We enrich the classical scheme for metric perturbations over a curved background by also including matter fields and metric conformal fluctuations.  We show in general that a conformally modulated metric induces dephasing as a result of an effective nonlinear Newtonian potential obtained in the appropriate non-relativistic limit of a minimally coupled Klein-Gordon field.  The special case of vacuum fluctuations is considered and a quantitative estimate of the expected effect deduced. Secondly, we address the question of how conformal fluctuations could physically arise.  By applying the random gravity framework we first show that standard GR seems to forbid spontaneous conformal metric modulations.  Finally we argue that a different result follows within scalar-tensor theories of gravity such as e.g. Brans-Dicke theory. In this case a conformal modulation of the metric arises naturally as a result of the fluctuations in the Brans-Dicke field and quantum dephasing of a test particle is expected to occur.  For large negative values of the coupling parameter the conformal fluctuations may also contribute to alleviate the well known problem of the large zero point energy due to quantum matter fields.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Space and time ; General relativity (Physics)