Torsion cosmology and beyond


Barker, W. (2020). Torsion cosmology and beyond. Perimeter Institute. https://pirsa.org/20120009


Barker, William. Torsion cosmology and beyond. Perimeter Institute, Dec. 08, 2020, https://pirsa.org/20120009


          @misc{ pirsa_20120009,
            doi = {10.48660/20120009},
            url = {https://pirsa.org/20120009},
            author = {Barker, William},
            keywords = {Cosmology},
            language = {en},
            title = {Torsion cosmology and beyond},
            publisher = {Perimeter Institute},
            year = {2020},
            month = {dec},
            note = {PIRSA:20120009 see, \url{https://pirsa.org}}

William Barker Kavli Institute for Cosmology Cambridge


Torsion is a popular ingredient in gravity, yet fraught with quantum and classical pathologies. I develop a novel torsion theory, consistent with power-counting and unitarity. The Friedmann equations emerge (with dark energy and radiation), as do pp waves and the Schwarzschild vacuum, all without an Einstein-Hilbert term. I show that cosmology sees torsion as a non-canonical scalar, revealing a rich phenomenology of conformal or waterfall inflatons, and cuscutons. I finally argue that future work will be driven less by toy-models, and more by computer surveys. I advocate Hamiltonian and effective field theory approaches to non-Riemannian geometry in general, relevant to ultraviolet completion and modified gravity alike. Such methods should be oriented towards the ultimate test of gravity: observed cosmological structure.