# Physics 4400: Statistical Mechanics

**4400 Statistical Mechanics** covers ensembles. Classical and quantum statistical mechanics. Statistical mechanics of phase transitions. Advanced topics in statistical mechanics.

CO: PHYS 3750

PR: PHYS 3400 and 3750

Statistical mechanics applies fundamental concepts from the worlds of classical mechanics, quantum mechanics and mathematical statistics and probability that provide the foundation for understanding at the microscopic level of how we experience everyday phenomena, such as the light bulbs and melting ice. Statistical mechanics bridges the microscopic (how particles behave according to quantum mechanics or microscopic laws) and the macroscopic (laboratory measurables involving an Avogadro number of these particles). A crucial feature of statistical mechanics is its ability to quantify the role of temperature. Collections of atoms or molecules can behave very differently at different temperatures. Phase transitions can occur within the same material to states of matter with wildly different behaviors. The resistance of metals can change by many orders of magnitude as temperature changes. Helium can exhibit superfluidity at very low temperature. All of these phenomena, and Everything we observe in the lab and in nature can (either in practice or in principle) be understood at a very fundamental (atomic- or sub-atomic scale) level through the concepts and mathematical formalism of statistical mechanics: How large numbers of particles (matter) behave.