Physics Department, Princeton University

I work on string theory and its applications to the understanding of black holes, phase transitions, and strongly coupled gauge theories. I focus particularly on the gauge-string duality, which relates gauge theories in four flat spacetime dimensions to string theory in five or ten curved dimensions. The gauge theories that can be described in this way are relatives of quantum chromodynamics, which is the theory of quarks and gluons.

There is growing evidence that the gauge-string duality describes aspects of heavy ion collisions. Such collisions cause protons and neutrons to melt into their constituent quarks and gluons, and it is generally believed that a locally thermalized state forms: the quark-gluon plasma. The strategy of the gauge-string duality is to compare the properties of the quark-gluon plasma to black holes in five curved dimensions. The results of such comparisons include predictions for the shear and bulk viscosity and the magnitude and pattern of energy loss from energetic heavy quarks.

I have long been interested in black hole phase transitions, especially the tendency for horizons to become spatially inhomogeneous. I recently suggested mechanisms by which black holes can go through a superconducting phase transition at finite temperature, and I have investigated the fermion response to superconducting black hole backgrounds.

I maintain interests also in theoretical cosmology and in more formal aspects of the gauge-string duality.  I also recently wrote a book on string theory for the layperson, entitled The Little Book of String Theory.  You can find out more about it on the publisher's web page, and also here. 

You can visit my homepage and my research group's page.