Natural Philosophy: The Logic of Physics Volume Two: The Quantum Theory of Everything The first volume of NATURAL PHILOSOPHY: THE LOGIC OF PHYSICS is used as the textbook for the first two years of the physics program at Cathedral High School in Indianapolis, Indiana. But the students have requested one or two additional years for a four-year physics majors program at Cathedral High School. This present volume is written to serve as the textbook for the second half of the physics program. The foundation for physics in the twenty first century is quantum mechanics; hence this second volume is devoted to developing that subject. Within that context, the physics of condensed matter is of great importance in 21st century technology. Thus, this book significantly stresses topics in condensed matter physics. In studying this book, certain topics can be stressed. Electromagnetic Theory: chapters 8 and 12 of volume one and chapter 13 of volume two Atomic and Nuclear Physics: chapters 16, 17, and 18 of volume two Condensed Matter: chapters 13, 14, 19 and 20 of volume two Quantum Optics: chapters 14 and 18 of volume two Chemical Engineering: chapter 19 of volume two The Physical Meaning of Quantum Mechanics: chapter 21 of volume two All required mathematics is developed when needed in the context of physics, but in doing so, all theorems are rigorously proved. The authors attempt to introduce new research topics at the time of writing this book. Instructors are encouraged to continue to discuss research topics. Physics students should learn what is not understood as well as understood.