Phase Transitions

This lecture covers the concept of phases and phase transitions, discussing the characteristics of different phases such as solid, liquid, gas, plasma, and superfluidity. It also explains the creation of plasma through ionization and the transition from gas to solid using examples like carbon dioxide. The lecture delves into the concavity of entropy, convexity of internal energy, stability criteria based on entropy and thermodynamic potentials, and the conditions for phase transitions. It explores the stability of entropy, criteria for stability related to internal energy, and volume, as well as the local and global conditions of concavity and convexity. The lecture concludes with a detailed analysis of stable states tangent to entropy and the implications of phase transitions.