While the two previous books entitled Introduction to Modern Physics‎:‎ Theoretical Foundations and Advanced Modern Physics‎:‎ Theoretical Foundations exposed the reader to the foundations and frontiers of today‎'‎s physics‎,‎ the goal of this third volume is to cover in some detail several topics omitted in the essentially linear progression of the first two‎.‎This book is divided into three parts‎.‎ Part 1 is on quantum mechanics‎.‎ Analytic solutions to the Schrodinger equation are developed for some basic systems‎.‎ The analysis is then formalized‎,‎ concluding with a set of postulates for the theory‎.‎ Part 2 is on applications of quantum mechanics‎:‎ approximation methods for bound states‎,‎ scattering theory‎,‎ time‎-dependent perturbation theory‎,‎ and electromagnetic radiation and quantum electrodynamics‎.‎ Part 3 covers some selected topics in relativistic quantum field theory‎:‎ discrete symmetries‎,‎ the Heisenberg picture‎,‎ and the Feynman rules for quantum chromodynamics‎.‎The three volumes in this series taken together provide a cl‎.‎‎.‎‎.‎