Joseph Polchinski moved to UC Santa Barbara in 1992, where he was a Professor of Physics and a Permanent Member of the Kavli Institute for Theoretical Physics. Polchinski's contributions to theoretical physics include a modern formulation of renormalization theory and some of the original work on the string landscape.  He is best known for his discovery of D-branes, extended structures that appear to be central to the mathematics and physics of string theory.  He is also the author of a widely used two-volume text on string theory.