Research Interests


Research Interests

Primarily, to answer the question 'What is String Theory?' More generally, particle physics and all applications of quantum field theory. My main recent interests have centered around gauge/gravity duality as the fundamental principle underlying string theory. This includes reduced models of black holes, the connection between bulk spacetime locality and the properties of the dual field theory, and attempts to identify the duals to realistic string vacua. I have recently begun to work on AdS/condensed matter duality, both because of the interesting quantum field theory questions, and because it gives new perspectives on the duality itself.

From the introduction to 'What is String Theory?', presented at the Les Houches Summer School, 1994:

While I was planning these lectures I happened to reread Ken Wilson's account of his early work [1], and was struck by the parallel between string theory today and quantum field theory thirty years ago. Then, as now, one had a good technical control over the perturbation theory but little else. Wilson saw himself as asking the question ``What is quantum field theory?'' I found it enjoyable and inspiring to read about the various models he studied and approximations he tried (he refers to ``clutching at straws'') before he found the simple and powerful answer, that the theory is to be organized scale-by-scale rather than graph-by-graph. That understanding made it possible to answer both problems of principle, such as how quantum field theory is to be defined beyond perturbation theory, and practical problems, such as how to determine the ground states and phases of quantum field theories.

In string theory today we have these same kinds of problems, and I think there is good reason to expect that an equally powerful organizing principle remains to be found. There are many reasons, as I will touch upon later, to believe that string theory is the correct unification of gravity, quantum mechanics, and particle physics. It is implicit, then, that the theory actually exists, and `exists' does not mean just perturbation theory. The nature of the organizing principle is at this point quite open, and may be very different from what we are used to in quantum field theory.

1. K. Wilson, Rev. Mod. Phys. 55, 583 (1983).