Chris McMullen is a physics instructor at Northwestern State University of Louisiana. He earned his Ph.D. in phenomenological high-energy physics (particle physics) from Oklahoma State University in 2002. Originally from California, he earned his Master's degree from California State University, Northridge, where his thesis was in the field of electron spin resonance. He has published several papers on the prospects for discovering large superstring-inspired extra dimensions at the Large Hadron Collider. Dr. McMullen taught a special thermodynamics course geared toward advanced students, which combined the usual third-semester calculus-based introduction to thermal physics together with the more advanced formulation of equilibrium thermodynamics. From this, he observed the disparity between the two approaches, and developed this textbook to help bring them together in a more unified way.