A graduate-level textbook on thermal physics covering classical thermodynamics, statistical mechanics and its applications.This is a textbook for second- and third-year graduate students studying topics such as the theory of complex analysis, classical mechanics, classical electrodynamics, and quantum mechanics. The central theme of the book is that, given the Hamiltonian for a system, it is possible to calculate the thermodynamics correlation function, either numerically or through the use of infinite series. The book is self-contained, with all required mathematics included either in the text or in Appendixes. The text includes many exercises designed for self-study.This is a textbook for second- and third-year graduate students studying topics such as the theory of complex analysis, classical mechanics, classical electrodynamics, and quantum mechanics. The central theme of the book is that, given the Hamiltonian for a system, it is possible to calculate the thermodynamics correlation function, either numerically or through the use of infinite series. The book is self-contained, with all required mathematics included either in the text or in Appendixes. The text includes many exercises designed for self-study.This text by one of the originators of the cluster variation method of statistical mechanics is aimed at second- and third-year graduate students studying such topics as the theory of complex analysis, classical mechanics, classical electrodynamics, and quantum mechanics. The central theme is that, given the Hamiltonian for a system, it is possible to calculate the thermodynamics correlation function, either numerically or through the use of infinite series. The book is self-contained, with all required mathematics included either in the text or in Appendixes. The text includes many exercises designed for self-study.1. Laws of thermodynamics; 2. Thermodynamic relations; 3. The ensemble theory; 4. System Hamiltonians; 5. The density matrix; 6. The cluster vlC>