Speaker
Description
The Cosmological Principle establishes the symmetries of the Universe on large scales. The inflationary paradigm and observations suggest that the universe has nearly flat spatial sections and, consequently, it has an approximate Euclidian symmetry group. Most cosmological scenarios realise this symmetry in a trival manner, although some non-trivial realisations have also been explored. All these realisations occur off-shell so they are not subject to the specific dynamics of the model. I will present a class of scenarios with an on-shell realisation of the symmetries so the compliance with the Cosmological Principle only occurs for solutions of the equations of motion. This on-shell realisastion has remarkable consequences like the mixing of different helicity cosmological perturbations or preferred direction effects on an an exact FLRW geometry.