PIRSA:19090110

Video URL

https://pirsa.org/19090110

The cosmological non-constant and Cartan's spiral staircase

Magueijo, J. (2019). The cosmological non-constant and Cartan's spiral staircase. Perimeter Institute for Theoretical Physics. https://pirsa.org/19090110

Magueijo, Joao. The cosmological non-constant and Cartan's spiral staircase. Perimeter Institute for Theoretical Physics, Sep. 19, 2019, https://pirsa.org/19090110 

          @misc{ scivideos_PIRSA:19090110,
            doi = {10.48660/19090110},
            url = {https://pirsa.org/19090110},
            author = {Magueijo, Joao},
            keywords = {Quantum Gravity},
            language = {en},
            title = {The cosmological non-constant and Cartan{\textquoteright}s spiral staircase},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2019},
            month = {sep},
            note = {PIRSA:19090110 see, \url{https://scivideos.org/pirsa/19090110}}
          }

Joao Magueijo Imperial College London

Talk numberPIRSA:19090110
DOI10.48660/19090110
Source RepositoryPIRSA
Collection
Talk Type Scientific Series
Subject

Abstract

We review recent efforts to turn the cosmological constant into a dynamical variable without an ungainly proliferation of free parameters. In a cosmological setting where parity invariance is imposed (along with homogeneity and isotropy) this leads to phenomenological disaster. However, in this theory it is possible to construct parity violating Friedman models due to torsion, a re-enactment of "Cartan's spiral staircase". We examine the Hamiltonian structure of the 2 branches (parity compliant and parity violating) and conclude that they must correspond to different theories, with different numbers of degrees of freedom. Parity violation may save these models phenomenologically, giving observational relevance to the Pontryagin invariant (and possibly the Immirzi parameter) in cosmology.