This text presents an introduction to relativity, quantum mechanics, and statistical physics as well as applications of these theories to molecular physics, condensed matter physics, nuclear physics, particle physics, and cosmology. Writing in a student-friendly and accessible manner, the authors strike the perfect balance, mixing relevant applications (many new to this edition) with the appropriate level of theory. A new Web-based simulation software package, QMTools, complements the text and provides modeling tools to help students visualize abstract concepts. Icons are provided throughout the text to highlight areas in which this software can enhance understanding.