Nonequilibrium aspects of physical cosmology

About 100-150 years ago, pioneers of statistical mechanics understood how to correct thermodynamics. Today, static and dynamic fluctuations can be observed in much greater detail thanks to sensational technological advances in probing and sensing. True in chemistry and for biophysics, it also matters for physical cosmology. Cosmology has become a precision science with detailed measurements of fluctuations in temperature and mass/energy distributions. That has been developed in a number of missions, and more are planned and called for. The present project wants to take the statistical mechanical side of physical cosmology and zoom in on possible nonequilibrium features. After all, the early universe gravitational degrees of freedom were out-of-equilibrium and when coupled to matter, the remains of nonequilibrium are visible even today (e.g. as the arrow of time). The thermal history of the universe combines cosmic expansion with gravitational clustering, and its study has led to some of the most foundational puzzles of physics such as on the nature of structure formation and dark energy. Our project will take a statistical mechanical view where fluctuations in geometry will be related to gravitational entropy. Nonequilibrium features in the primordial plasma will be important for the understanding of possible corrections to the Planck law of the cosmic microwave background. Even solar plasma shows important nonequilibrium effects ready for statmech modeling.