David Gross is Chancellor's Chair Professor of Theoretical Physics and former director of the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara. Questions about renormalization in particle physics, symmetries in physics, and the relation between quantum theory and gravitation belong to his main fields of research. In 2004 he received the Nobel Prize for Physics for his discovery of the asymptotic freedom according to which the closer quarks are to each other, the weaker is the interaction between them. Gross’ discovery of asymptotic freedom was central to the development of quantum chromodynamics.