The cosmological non-constant and Cartan's spiral staircase


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


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


          @misc{ pirsa_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},
            year = {2019},
            month = {sep},
            note = {PIRSA:19090110 see, \url{https://pirsa.org}}

Joao Magueijo Imperial College London

Talk Type Scientific Series


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.