Research in theoretical physics, to be carried out by one of the new Presidential Young Investigators for 1991, will include studies in quantum field theory, elementary particle theory, string theory, and quantum gravity. The research in quantum gravity will focus initially on two-dimensional gravity, which hopefully serves as a simple model of gravity in the real four-dimensional world. The achievement of an understanding of gravity is one of the outstanding problems in physics. String theory may help to solve this problem and at the same time to achieve a unified description of all the forces of nature.
