The laws of Thermodynamics underpin everything from life itself to the evolution of the universe. Moreover, they also address fundamental problems such as the “arrow of time”. Although Thermodynamics was developed in the nineteenth century, modern developments have reinforced Einstein’s view that it is "the only physical theory of universal content which I am convinced will never be overthrown.” Whilst statistics allow us to calculate the macroscopic properties of a system from microscopic theory, Thermodynamics has a power all of its own, even when we don’t understand the microscopic physics. The central idea that links the two approaches is the concept of entropy, the understanding of which lies at the heart of this module. The main topics are organised as follows:
1. Statistical Physics: Kinetic theory and molecular collisions; Mean free-path, diffusion and the random walk; Binomial, Poisson and Gaussian distributions.
2. Thermal Equilibrium: Microstates, macrostates and Boltzmann entropy; Temperature and the Boltzmann distribution; Equipartition, harmonic oscillators, black-body radiation, stimulated emission and lasers.
3. Classical Thermodynamics: 1st Law and 2nd Law (Clausius & Kelvin); Reversible & irreversible processes; Reversible heat, latent heat and heat capacity; Carnot cycle, heat engines and refrigerators; Functions of state, Gibbs & Helmholtz free energies and enthalpy; Thermodynamics of rubber elasticity, surface tension and liquid-vapour equilibrium; Maxwell Relations and Joule-Kelvin effect; Absolute Zero and the 3rd Law of Thermodynamics.
4. Advanced Topics: Perpetual Motion and Maxwell’s Demon; Information, Gibbs entropy and negative temperatures; Introduction to quantum statistics of identical particles.