Ph.D Student | Eran Rosenthal |
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Subject | The Self Force in Curved Spacetime |

Department | Department of Physics |

Supervisor | Full Professor Ori Amos |

This research includes two main topics: first, a
consistent formulation of the extended-object approach for the explanation and
calculation of the self-force phenomenon in flat spacetime. In this approach, one considers a charged
extended-object of a finite size _{} that accelerates in a nontrivial
manner, and calculates the total force exerted on it by the electromagnetic field (whose source is the
charged object itself), at the limit _{}. Previous study of this approach
ended up with expressions for the total electromagnetic force that do not have the form required
by mass-renormalization (in the special case of a spherical charge
distribution, this _{} term was found to be 4/3 times larger than the desired quantity). In this thesis
we use energy-momentum conservation in the object's momentary rest frame, and
derive the correct notion of total electromagnetic force. This completely cures the
problematic O(1/_{}) term, for any object's shape,
and yields the correct self-force at the limit _{}.

In particular, for a spherical charge distribution, the above ''4/3 problem'' is resolved.

The second topic in this research is the derivation and implementation of a new regularization approach for the calculation of the scalar self-force in curved spacetime.

In this approach the scalar self-force in curved spacetime is expressed in terms of the difference between two retarded scalar fields: the massless scalar field, and an auxiliary massive scalar field. This field difference combined with a certain limiting process gives a simple expression for the scalar self-force. We implement this approach in the special case of static particle in a Schwarzschild spacetime, thereby we show that the scalar self-force vanishes in this case.