241470 Random dynamical systems and stochastic porous media equations with nonlinear noise (V) (WiSe 2018/2019)

The problem of the generation of random dynamical systems by stochastic partial differential equations (SPDE) is one of the core open problems in the application of dynamical systems theory to SPDE. Despite its fundamental nature, most results are restricted to "simple" random perturbations of affine-linear structure. However, as we will see in this course, applications ranging from scaling limits of particle systems with interaction and branching to non-equilibrium statistical mechanics, lead to porous media equations perturbed by nonlinear multiplicative or nonlinear conservative noise. We will first convince ourselves that established methods such as the variational approach to SPDE cannot be applied to these equations, let alone prove the generation of random dynamical systems. Then, based on entropy and kinetic theory we will prove their well-posedness. This will lead to a strong notion of uniqueness, so-called path-by-path uniqueness, based on rough path theory which in turn proves the generation of a corresponding random dynamical system and opens the way to a qualitative analysis of the (stochastic) flow of the solutions.