This book and its prequel (Theories of Matter, Space, and Time: Classical Theories) grew out of courses that are taught by the authors on the undergraduate degree program in physics at Southampton University, UK. The authors aim to guide the full MPhys undergraduate cohort through some of the trickier areas of theoretical physics that undergraduates are expected to master. To move beyond the initial courses in classical mechanics, special relativity, electromagnetism and quantum theory to more sophisticated views of these subjects and their interdependence. This approach keeps the analysis as concise and physical as possible whilst revealing the key elegance in each subject discussed.

This second book of the pair looks at ideas to the arena of Quantum Mechanics. First quickly reviewing the basics of quantum mechanics which should be familiar to the reader from a first course, it then links the Schrodinger equation to the Principle of Least Action introducing Feynman's path integral methods. Next, it presents the relativistic wave equations of Klein, Gordon and Dirac. Finally, Maxwell's equations of electromagnetism are converted to a wave equation for photons and make contact with Quantum Electrodynamics (QED) at a first quantized level. Between the two volumes the authors hope to move a student's understanding from their first courses to a place where they are ready to embark on graduate level courses on quantum field theory.

Nick Evans, Southampton University
Nick completed his PhD in collider phenomenology in 1993 at Southampton University. He performed his early research work at Yale and Boston Universities in the US before returning to Southampton in 1999 on a UK government 5 year fellowship. His work centered on strongly interacting particle systems, including composite Higgs models, and he played a large role in applying string theory to study the strong nuclear force and the mechanism of mass generation. Much of his work centers on the structure of the vacuum so in a sense he works on nothing. He is now a Professor at Southampton University and the Director of the Faculty of Physical Science and Engineering Graduate School.

Steve King, Southampton University
Steve completed his PhD in QCD perturbation theory in 1980 at Manchester University. He was a postdoctoral fellow at Oxford University, where he worked on composite models, before moving to Harvard and Boston Universities in the US, where he worked on technicolour and collider phenomenology. Returning to Southampton in 1987, he won a 5 year fellowship to work on lattice QCD and top quark condensates. Soon after becoming a Lecturer, he turned his attention to supersymmetry, cosmology, strings, unification, flavour symmetry models and neutrinos. He is now Professor and First Year Director of Studies in Physics and Astronomy at Southampton.

Table of Contents
Non-relativistic quantum mechanics
Path integral approach to quantum mechanics
Relativistic quantum mechanics
Quantum electrodynamics