Abstract
The AdS/CFT correspondence is one of the most importantdiscoveries 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. This means that to compute any measurable quantity in the quantum theory, we can instead do a computation in
classical general relativity, and vice versa. 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. Originally discovered
in the context of string theory, this duality has now found a wide
range of applications, from condensed matter physics to high
temperature plasmas in quantum chromodynamics (QCD).
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. Certain quantum
field theories (such as QCD) enjoy a property called confinement,
which in the case of QCD states that quarks can not be isolated.
Using mostly numerical methods, I have studied how confinement
affects thermalization in quantum field theories. We found that
sometimes the system never thermalizes and field theory
observables undergo interesting quasiperiodic behaviour. In another
line of research, I have studied formation of black holes in three
dimensions which due to the simplified nature of threedimensional
gravity can be done using analytical methods. This has led to the
discovery of new solutions of threedimensional gravity
corresponding to the formation of black holes without spherical
symmetry, which can provide a deeper understanding of
thermalization in twodimensional quantum field theories. In a third
line of research, I have studied higher spin gravity in three
dimensions, an exotic extension of threedimensional gravity which
includes fields with spin higher than two, and found a new method to
construct black hole solutions carrying higher spin charge.
Date of Award  5 Jul 2017 

Original language  English 
Awarding Institution 

Supervisor  Ben Craps (Promotor), Alexandre Sevrin (Promotor), M. Henneaux (Promotor), Stéphane Detournay (Jury), Sophie de Buyl (Jury), Jan De Boer (Jury) & Thomas Van riet (Jury) 