Black Holes, Holography, and String Theory

As a quantum theory of gravity, string theory is expected to answer many outstanding questions regarding the intersection of Einstein's classical gravitational theory with the quantum field theory of the Large Hadron Collider.  A few of these questions are: the black hole "information paradox"; the cosmological constant; and the holographic nature of gauge theories.

The information paradox relates to the entropy of black holes and the associated Hawking radiation.  In classical general relativity, a black hole should be unique, and therefore not have an entropy.  But quantum black holes have a well-defined entropy, temperature, and so on.  One way that string theory can reconcile these viewpoints is with the notion of "black hole microstates", which might be able to explain both the classical gravitational picture and the entropy.

Another problem for string theory to resolve is the cosmological constant, which is:  Why does our universe have a cosmological constant which both positive and very small, but not zero?  There are some proposed ways in string theory for obtaining positive cosmological constant, and part of my project is to investigate whether these methods work.

Finally, another important topic in string theory is holography, which relates quantum field theories in 4 dimensions to gravity theories in 5 dimensions.  In particular, I will use holography to study confining gauge theories, which resemble the quantum field theories of the real world or the LHC.