New perspectives in gravity beyond General Relativity: from fundamental physics to strongly gravitating systems

Coates, Andrew (2018) New perspectives in gravity beyond General Relativity: from fundamental physics to strongly gravitating systems. PhD thesis, University of Nottingham.

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General Relativity (GR) has been extremely successful experimentally. However there are several reasons to consider that GR is not the complete theory of gravity. Although directly probing quantum gravity in the near future seems highly unlikely observations of the non- perturbative regime of classical gravity is improving, so any classical modification of gravity may well be testable.

In this thesis we will focus on two interesting depatures from GR inspired by quantum gravity: violations of Lorentz symmetry and the weak equivalence principle.

Lorentz violating (LV) gravity theories are interesting for various reasons. For example: they may have improved UV behaviour as quantum theories. Additionally testing principles which are fundamental to our understanding of nature is extremely important.

We demonstrate how the causality of certain types of LV theories is realised. We then show how the relationship between two different LV theories could be used to find whether or not black holes can truly form from collapse, at least in spherical symmetry.

One may be worried about whether or not LV in gravity can spoil the Lorentz invariance of matter. We generalise some known results about this problem in Horava gravity and then consider the viability of one proposal to correct this problem.

Weak equivalence principle violations alter the structure of matter. By developing a simple model we demonstrate that one can maintain the weak equivalence principle in the solar system, while breaking it in high-curvature regimes. We go on to demonstrate the efficacy of the mechanism.

This thesis is largely aimed at tackling questions related to the strong field regime in alternative theories of gravity: a topic of increasing interest.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Sotiriou, Thomas
Weinfurtner, Silke
Subjects: Q Science > QC Physics > QC170 Atomic physics. Constitution and properties of matter
Faculties/Schools: UK Campuses > Faculty of Science > School of Mathematical Sciences
Item ID: 48217
Depositing User: Coates, Andrew
Date Deposited: 19 Jul 2018 04:40
Last Modified: 07 May 2020 18:45

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