Particle Propagators from Discrete Spacetime

          @misc{ pirsa_PIRSA:08040043,
            doi = {10.48660/08040043},
            url = {https://pirsa.org/08040043},
            author = {Johnston, Steven},
            keywords = {Particle Physics},
            language = {en},
            title = {Particle Propagators from Discrete Spacetime},
            publisher = {Perimeter Institute},
            year = {2008},
            month = {apr},
            note = {PIRSA:08040043 see, \url{https://pirsa.org}}
          }
          

Abstract

How sure are you that spacetime is continuous? One of the more radical approaches to quantum gravity, causal set theory, models spacetime as a discrete structure: a causal set. Allowing the possibility that spacetime is discrete then how should we do physics on it? Carrying over the usual continuum descriptions in terms of differential equations seems like a difficult option. This talk begins with a brief introduction to causal sets then describes an approach to modelling the propagation of scalar particles on a causal set. We obtain the continuum causal retarded propagator by summing quantum mechanical amplitudes assigned to paths in the causal set - a kind of \'discrete path integral\' that agrees with the continuum result. The propagator so obtained should serve as a building block towards a model for quantum field theory on a causal set.