Foundations of Bioenergetics provides an introduction to the physical foundations of bioenergetics and the methods of applying these constructs to biological problems. It combines parts of thermal physics, biochemistry, ecology, and cellular and organismic biology into a single coherent work. Much of the material in this volume comes from "Entropy for Biologists," an introductory thermodynamics book aimed particularly at life scientists. Some of the topics originally appeared in the monograph "Energy Flow in Biology." The current volume expands on that material with respect to biological applications and attempts to bridge the gap between physics and biology. The book explains basic concepts such as energy, temperature, the second law of thermodynamics, entropy, information theory, and statistical mechanics. It discusses the relations between thermodynamics and statistical mechanics, free-energy functions, radiant energy, the free energy of cells and tissue, chemical kinetics, and cyclic flows. It examines the relationships between energy flows and biological processes; applications of the concepts of Gibbs free energy, chemical potential, and activity; and measurements of temperature, energy, and thermochemical quantities. The book also includes chapters that deal with irreversible dynamics, irreversible theory, and osmotic flow.