Research in theoretical physics, to be carried out by one of the new Presidential Young Investigators for 1991, will include a variety of studies on quantum field theory, high- energy physics, cosmology, and quantum gravity. Initial efforts will deal with the effects of a global charge on phase transitions in the early universe, and on conceptual difficulties relating to the quantum mechanics of the universe as a whole. The achievement of an understanding of the early evolution of the universe and of the quantum mechanics of the universe are very important challenges to theoretical physics.