The popular introductory course in theoretical physics covers all areas relevant to the diploma across seven volumes. Each volume thoughtfully provides the theoretical and physical tools necessary for the respective semester. Numerous exercises with detailed solutions serve to deepen the understanding of the material. The first part of the fifth volume begins with an inductive justification of quantum mechanics, and then, after examining and compiling the formal foundations of quantum mechanics, illustrates the new concepts and terminology using simple model systems. This new edition has been revised and expanded. The two-color presentation allows for a very clear and quick access to the course material.