Seminar by C. Marinoni (CTP Marseille), Cosmology with a Compass and a Straightedge

Wednesday 8 Jun 2011, 11:00 → 12:00 Europe/Paris

LPSC Grenoble

How can we extract information about the geometry of the universe using only a compass and a straightedge? Is General Relativity the correct theory of gravity on large cosmological scales? What does the universe looks like to an "extraterrestrial" distant observer? and how will it look in the distant future? Current ideas and answers will be reviewed and will serve as a frame for discussing the solution that we have recently worked out to an old cosmological problem posed by Alcock & Paczynski thirty years ago: is it possible to fix the constitutive parameters of the Friedmann equations in a purely geometric, model independent way? I will present our recipe and show that the proposed formalism already provides competitive constraints on the abundance and nature of the component that is causing the expansion of the universe to accelerate.