Mathematical Physics Seminar: Nicolai Rothe (Wuppertal)

Mathematical Physics Seminar 12:30-13:30

Speaker: Nicolai Rothe (Bergische Universität Wuppertal)

Title: A new cosmological model derived from the semiclassical Einstein equation

Abstract: We consider a new special case of the semiclassical Einstein equation. Therefore we choose a massless Klein-Godon field in combination with a flat-FLRW ansatz. This approach leads us to a coupled system of ODE’s for both the FLRW-scaling factor and the quantum state. The curvature coupling as well as the relevant renormalization constants are left as free parameters. The virtue of a massless field is, based on a recent work of Gottschalk and Siemssen, that for a special class of initial values the system of ODE’s decouples and similarly to Starobinki’s model we are left with a single ODE for the scaling factor. In this model we consider mathematical properties of the equation and its solutions depending on the parameters and suggest a few cosmological applications. With realistic initial values we obtain numerical solutions with many features that a cosmological should have. Only to mention some, Big-Bang solutions with an inflection point seem to be the generic case without any parameter fine-tuning. Furthermore generic solutions have a radiation dominated early phase and a ’dark energy’ dominated later phase.