Prerequisite: MSE 200 and MSE 227 are beneficial but not mandatory. This course provides an introduction to statistical thermodynamics (physics) and then discusses more advanced problems by covering the following topics: macroscopic vs. microscopic systems, statistical weight, calculus of probabilities, Boltzmann distribution function, Lagrange multipliers, mean energy and internal energy of particles. Statistical ensembles: microcanonical and canonical ensembles, canonical and molecular partition functions, heat capacity, auxiliary functions. Further ensembles: Grand-canonical and others, fluctuations. Partition functions: translational, rotational, and vibrational partition functions, electronic and nuclear contributions, properties of the ideal gas, and equipartition principle. Monoatomic crystals: Einstein and Debye model of heat capacity. Classical statistics and quantum statistics: density of states, quantum statistics, bosons, fermions, and their microstates, distribution functions: Maxwell's velocity distribution, Fermi-Dirac statistics (electron gas), Bose-Einstein statistics (photon gas). Equilibria and dynamics: equilibrium constants and collision theory.