Title: Topos Methods in the Foundations of Physics
Abstract: More than forty years have passed since I first became interested in the problem of quantum gravity. During that time, there have been many diversions and, perhaps, some advances. Certainly, the naively optimistic approaches have long been laid to rest, and the schemes that remain have achieved some degree of stability. The original “canonical” program evolved into loop quantum gravity, which has become one of the two major approaches. The other, of course, is string theory—a scheme whose roots lie in the old Veneziano model of hadronic interactions, but whose true value became apparent only after it had been reconceived as a theory of quantum gravity.