
Harold C. Steinacker Senior scientist Fakultät für Physik




Email: harold.steinacker at univie.ac.at Phone: +43 1 4277
73125 Office: 5th floor Rm
3525 
Research Interests : Theoretical and mathematical physics.
My primary research interest is the
theory of fundamental interactions, and to contribute to the
development of a quantum theory of fundamental interactions
including gravity. Specifically, I'm developing and following an
approach known as „Matrix Theory“, focusing on the IKKT or IIB matrix
model. This can be viewed as a constructive approach to
string theory, which avoids the "landscape" problem and its
inherent lack of predictivity. The model is viewed as
fundamental starting point, rather than an effective description
of string theory. The model is extremely simple, and leads
naturally to a quantum structure of spacetime. A central aspect
of this programe is to establish a suitable notion of quantum
geometry, which is fairly well developed by now.
The basic idea is that 3+1dimensional spacetime arises as a
(branelike) solution of the matrix model, and physics arises
from fluctuations on this brane. For YangMills gauge theories,
this works in a very nice and convincing way. The main challenge
has been to recover gravity. The 10dimensional (super)gravity
usually studied in string theory is not the appropriate answer
(it merely leads to a weak shortrange interaction on the
brane). Rather, gravity emerges through an intrinsic
dynamical frame on the spacetime brane, which is linked
to its internal quantum structure. Its quantization is then
defined nonperturbatively by integrating over all matrices.
Recent progress strongly indicates
that this scenario is indeed realized on solutions with a
particular structure, dubbed „covariant quantum spaces“. They
lead to the spin 2 fluctuations required for gravity, as well as
a tower of higherspin modes. Simple cosmological
spacetime solutions featuring a Big Bounce were found,
and the fluctuation
modes were shown to be ghostfree.
In particular, the
linearized Schwarzschild solution was found, and recent
progress allows to access also the nonlinear
regime. There is growing evidence that the approach leads
to a nearrealistic form of gravity, which  unlike the Einstein
Hilbert action  would be wellsuited for quantization. See also
a related
press
release and a review article.
The goal in the next years is to develop this theory further.
This work has been supported by the
Austrian Science Fund FWF
through various grants. This support was crucial to carry out
this line of research at the University of Vienna, and is
gratefully acknowledged.
Apart from this longterm 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.
Selected talks, providing an
introduction & overview of my recent work
Publications
InSPIRE HEPpreprint database: search
Research Project "Covariant Quantum
Spaces, Higher Spin, and Gravity"
supported
by the FWF, P
32086
This project focuses on the recently
discovered 3+1dimensional covariant quantum spacetimes, which
lead to higherspin gauge theories in the framework of YangMills
matrix models. The focus will be on the gravity sector, which
arises from spin 2 fluctuation modes on these spaces. This should
provide a promising framework for quantum gravity, and we will aim
to develop this as far as possible.
Members of this research group: Yuhma Asano (postdoc),
Veronika Bachleitner (Master's student), Clemens Kerschbaumer
(Master's student), H.S.
(completed) Research Project "Squashed
Extra Dimensions in Gauge Theory and Matrix Models"
supported
by the FWF, P
28590
(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
completed (I was member of the management committee & leader
of the working group on gravity models)
Training school Quantum
Structure of Spacetime and Gravity 2016
Current and recent teaching
Lecture notes:
related seminars & conferences
Workshop Matrix Models for Noncommutative Geometry and String Theory
international workshop on "Noncommutative Geometry, Duality and Quantum Gravity"
Training school Quantum Structure of Spacetime and Gravity 2016
Workshop on Noncommutative Field Theory and Gravity , Corfu, September 19  26, 2015