String theory

String theory connects the microscopic quantum world of elementary particles to the macroscopic world of gravity and geometry. Physicists believe that it may have the potential to achieve two very ambitious goals: (1) to give a complete mathematical description of the microscopic laws that determine the properties of elementary particles and the forces that act on them and (2) to explain the origin and evolution of the Universe. Much has been achieved, but string theory is still a work in progress. This talk will give a historical overview of the subject and discuss (without technical details) some of the problems that remain to be overcome.