  The AdS/CFT correspondence is one of the most important discoveries in
theoretical physics in recent years. It states that certain quantum mechanical
theories can actually be described by classical gravity in one higher
dimension, in a spacetime called anti-de Sitter (AdS) space. What makes this
duality so useful is that it relates theories with weak coupling to theories
with strong coupling and thus provides a new tool for tackling strongly coupled
quantum field theories, which are notoriously difficult to handle using
conventional methods. During the course of my PhD I have mostly studied time
dependent processes, in particular thermalization processes, in quantum field
theories using the AdS/CFT correspondence. On the gravity side, this is dual to
dynamical formation of black holes from the collapse of matter fields. By
studying the gravitational collapse process in detail, we can then draw
conclusions about the dynamical formation of a thermal state in the dual
quantum field theory. Using mostly numerical methods, I have studied how
confinement affects thermalization in quantum field theories, where the system
may never thermalize and field theory observables undergo interesting
quasiperiodic behaviour. I have also studied formation of black holes in three
dimensions which due to the simplified nature of three-dimensional gravity can
be done using analytical methods. This has led to the discovery of new
solutions of three-dimensional gravity corresponding to the formation of black
holes without spherical symmetry, which can provide a deeper understanding of
thermalization in two-dimensional quantum field theories. In a third line of
research, I have studied higher spin gravity in three dimensions, an exotic
extension of three-dimensional gravity which includes fields with spin higher
than two, and we outline a new method to construct black hole solutions
carrying higher spin charge.
