Lecturer and principal investigator, Universität Wien
Research Interests : Theoretical and mathematical physics.
My core interest is the theory of fundamental
interactions. I grew up scientifically in the formal
high-energy theory group at UC Berkeley (advisor: Bruno
Zumino), and my research is aimed towards a quantum
theory of all fundamental interactions including gravity. More specifically, I'm following and developing an
approach known as „Matrix Theory“, focusing on the IKKT model
(which is closely related to the BFSS model).
This can be viewed as a constructive approach to string
theory, which avoids the issue of
a "landscape" of compactifications and the inherent lack of
predictivity. However, the model is viewed here as
fundamental starting point, rather than an effective
description of string theory. The model is not only
extremely simple, it also naturally leads to a quantum
structure of space-time, which is expected to arise in
The basic idea of this approach is to recover 3+1-dimensional space-time as a quantized brane solution of the matrix model, and the known physics from the fluctuations on this brane. For Yang-Mills gauge theories, this works in a very nice and convincing way. The main challenge is to recover gravity. While string theory usually relies on the 10-D bulk (super)gravity, this mechanism doesn't help here (it merely leads to a weak short-range interaction on the brane). However, gravity may emerge directly on the space-time brane. Once this is understood, its quantization would be defined naturally by the matrix model.
There is a very promising class of such space-time solutions, dubbed „covariant quantum spaces“: They naturally lead to the spin 2 fluctuations required for gravity, and seem to have just the right properties. In particular, a recently found cosmological space-time looks very promising, and a recent analysis provides strong evidence that gravity indeed arises. This is work in progress which needs to be developed further. See also the related press release.
work has been supported by the Austrian Science Fund FWF.
Without that support, it would not be possible for me to
continue this line of research at the University of Vienna.
Apart from this long-term project, I'm also interested in other topics in the context of the theory of elementary particles and fundamental interactions, quantum gravity, string theory, noncommutative geometry, random matrix theory, quantum groups, etc.
talks, providing an introduction &
overview of my recent work
Research Project "Squashed Extra Dimensions in Gauge Theory and Matrix Models"
supported by the FWF, P 28590
The focus of this project is to explore the physical
consequences of fuzzy extra dimensions, notably by certain
self-intersecting quantum geometries. This is directly relevant
to the above-mentioned Matrix Theory, but it also arise within
the framework of ordinary Yang-Mills gauge theory.
This has developed towards „covariant quantum spaces“, which allow to reconcile the notions of covariance and quantum space(time), and provide a promising basis for a higher spin extension of quantum gravity.
Members of this research group: Marcus Sperling
(postdoc), Timon Salar Gutleb (Master's student), Clemens
Kerschbaumer (Master's student), H.S.
(completed) Project "Branes, Gauge Theory and Gravity in Matrix Models"
supported by the FWF, P24713, related press release
(completed) project "Matrix Models, Quantum Spaces, and Gravity"
supported by FWF, P21610
Possible topics for a Master's thesis
COST network QSPACE
(I'm member of the management committee & leader of the working group on gravity models)
Training school Quantum Structure of Spacetime and Gravity 2016