Toward Spinfoam Cosmology

Francesca Vidotto, Carlo Rovelli, Eugenio Bianchi

Quantum cosmology is usually studied quantizing symmetry-reduced variables. Is it possible, instead, to define quantum cosmology starting from the full quantum gravity theory? In Loop Quantum Gravity, it is possible to cut the degrees of freedom in a suitable way, in order to define a cosmological model. Such a model provides a tool for describing general fluctuations of the quantum geometry at the bounce that replaces the initial singularity. I focus on its simplest version, a "dipole" formed by two tetrahedra. This has been shown to describe a universe with anisotropic and inhomogeneus degrees of freedom. Its dynamics can be given using the spinfoam formalism. I review the present state of this approach to quantum cosmology.