PRINCIPLE OF EVENT SYMMETRY

To accommodate topology change, the symmetry of space-time must be ext ended from the diffeomorphism group of a manifold to the symmetric gro up acting on the discrete set of space-time events. This is the princi ple of event-symmetric space-time. I investigate a number of physical toy models with this symmetry to gain some insight into the likely nat ure of event-symmetric space-time. In the more advanced models the sym metric group is embedded into larger structures such as matrix groups which provide scope to unify space-time symmetry with the internal gau ge symmetries of particle physics. I also suggest that the symmetric g roup of space-time could be related to the symmetric group acting to e xchange identical particles, implying a unification of space-time and matter. I end with a definition of a new type of loop symmetry which i s important in event-symmetric superstring theory.