Dr. RobertRobert C. Helling

Rm B3390, Arnold Sommerfeld Center, Theresienstraße 39, 80333 München, Germany, Email helling@atdotde.de, Tel. +49(0)892180-4523
I am the scientific coordinator of the Elite Master Programme "Theoretical and Mathematical Physics" at Ludwig-Maximilians-Universität München. My research is in the area of superstring theory and its nonperturbative version, M-Theory.

Before joining LMU, I studied at Hamburg University and the Albert Einstein Institute in Potsdam under Hermann Nicolai. Later, I was a postdoc at Humboldt University Berlin and DAMTP Cambridge and International University Bremen (now Jacobs Univsersity).

Me research includes the following areas:
  • In a certain sector, M-Theory is described by a quantum mechanical matrix model. Using perturbation theory one can compute scattering amplitudes and compare these to graviton scattering in supergravity. This is laid out in my PhD Thesis which summarises several papers. One of these studies rather general dynamics of moduli and has recently been of use in cosmological models. With Hermann Nicolai we wrote lecture notes on the M(atrix) model and supermembranes.
  • At small scales, one expects space-time manifold to resolve and to be replaced by a more general structure like non-commutative geometry. The non-commutative torus is a particularly simple example. Due to "Morita equivalence", it can have different descriptions that are physically equivalent. This we used to investigate continuity of scattering amplitudes on the parameter of noncommutativity, how a commutative theory can be dual to one with UV/IR-mixing and how to generalise SU(N) gauge theory to noncommutative spaces (seminar slides). In this paper we showed that non-commutativity at small scales has effects at macroscopic distances due to quantum effects. This casts serious doubts on the phenomenological usefulness of non-commutative theories.
  • The most general solutions of branes are hard to find, but those that preserve some supersymmetry have a simpler description due to BPS equations. We used these to investigate brane splitting and joining transitions in the dual gauge theory (seminar slides). This has applications in the stringy Higgs mechanism, G2 manifolds and N=1 theories in general.
  • Besides string theory, people use "loop quantum gravity" to approach the quantisation of gravity. We worked out the similarities and differences of the two approaches in the solvable worldsheet theory of the bosonic string which is a non-trivial yet tractable diffeomorphism invariant theory (seminar slides). More recent papers in this direction are here and in particular, covering loop cosmology and non-renormalizability of loop gravity, here.
  • Entanglement entropy, if not the underlying mechanism, is a toy model for the origin of the Beckenstein entropy of black holes. In this paper we studied the violation of the area law for fermionic entanglement entropy by proving a special case of a conjecture by Widom.
  • As a summerstudent I joint the protein folding group at the NEC Research Institute in Princeton, NJ. There, we found an explanation why natural proteins have secondary structure: This makes them better designable! This paper was published in Science and has 420+ citations according to Google Scholar.
SPIRES citation search (does not list papers on protein folding and mathematical physics).

I gave a talk at 26c3, the 2009 convention of the Chaos Computer Club, titled "Hacking the Universe". You can find a video recording here.

I have written a less technical account on the M(atrix)-Modell of M-Theory (in German) and how physical space-time can be an emergent concept in string theory (poster text). The latter won me the Schlössmann Award. I maintain atdotde, a blog partially on physics, and I should better maintain my personal home-page. I am a co-moderator of the String Coffee Table. In the past, I gave physics lectures based on a Star Trek theme for high school students. "Phaser, Wurmloch, Warpantriebe" are the slides.

Other interests include scuba diving, jazz music (active and passive), and programming. Here are a number of projects:

  • LogVyper, a TeX-based divelog with web interface that reads out my Suunto Vyper dive computer (there is also an old version that connected to my Aladin).
  • A seminar scheduling system with automated seminar list, poster mailing and email reminders for the Albert Einstein Institute.
  • A set of dynamic web pages for staff lists, office allocation, guest house administration etc used at the AEI as well.
  • A toolbox to create online conference proceedings including semi-automated transparency scanning and audio.
  • An formula ascii pretty printer that can be plugged into emacs.
  • As many others, I have written a sudoku solver/generator.
  • My OpenPGP public key can be found here.