Nonlocality in the causal set approach to quantum gravity

          @misc{ pirsa_PIRSA:23050130,
            doi = {10.48660/23050130},
            url = {https://pirsa.org/23050130},
            author = {Dowker, Fay},
            keywords = {Quantum Gravity, Cosmology},
            language = {en},
            title = {Nonlocality in the causal set approach to quantum gravity},
            publisher = {Perimeter Institute},
            year = {2023},
            month = {may},
            note = {PIRSA:23050130 see, \url{https://pirsa.org}}
          }
          

Abstract

The nonlocality of causal sets gives us hope of solving the cosmological constant puzzle (``why is the universe so smooth, big and old if there is only one scale---the discreteness scale---in the theory?’’) On the other hand locality, , GR and local QFT, must be recovered from quantum gravity in the continuum approximation at large scales, which is a challenge. If we are lucky though (like Goldilocks, the universe gets the nonlocality ``just right’’) nonlocality may be a rich source of phenomenology. Yasaman Yazdi’s talk will be on cosmological models based on the nonlocality of causal sets. I will give a couple of examples of more astrophysical phenomenological models based on simple assumptions---randomness due to spacetime uncertainty and Lorentz invariance---and pose a research question: is there a model of ``quantum swerves’’?