M.Sc Student | Orr Sela |
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Subject | Analyzing Quantum Effects at the Inner Horizon of a Reissner-Nordstrom Black Hole |

Department | Department of Physics |

Supervisor | Full Professor Ori Amos |

Full Thesis text |

The classical Einstein’s field equation of general relativity admits black hole solutions with internal structures that possess exotic features such as naked singularities, Cauchy horizons and bridges to other universes. Generally, however, classical solutions might be significantly affected by quantum phenomena. Such phenomena, for example, cause a (classical) stationary black hole solution to evaporate when the quantum nature of the fields residing in the black hole spacetime is taken into account. This evaporation occurs through the emission of the well-known Hawking radiation. In this thesis, we work under this semiclassical framework, according to which the gravitational field is treated classically as a curvature of spacetime, while all the other fields are taken as quantum fields residing in this background.

Previous studies claimed that the exotic, classical internal structure of the black hole solutions mentioned above is strongly modified by quantum vacuum effects associated with the Hawking evaporation process. In this work, we try to get some new insight into the nature of these modifications by considering a simple model with the above mentioned features: A massless, minimally coupled quantum scalar field on a Reissner-Nordstrom black hole background. The Reissner-Nordstrom geometry is a solution to Einstein’s field equation that describes a spherically symmetric, electrically charged black hole, and has two horizons - an outer (event) horizon and an inner (Cauchy) horizon. In this model, the modifications are expected to be maximal near the inner (Cauchy) horizon. In this semiclassical picture, we begin by deriving useful expressions for the two-point function in the interior region of the black hole. Then, we employ these expressions to calculate the expected leading-order divergence of the expectation value of the stress-energy tensor operator near the Cauchy horizon and show that its coefficient vanishes. This, in turn, suggests that the modification might be weaker than expected.