Rooted in the author's thirty years of classroom experience, this text strips quantum theory down to its most basic content by deriving its fundamental equations from the fewest possible physical principles. Development of Quantum Theory from Physical Principles presents the entire content of quantum theory and its formalism based on the uncertainty principle and the invariance principle. The treatment demonstrates that it is possible to establish the existence of specific pairs of conjugate observables and determine their properties. The text uses the two principles to derive the Klein-Gordon equation, and from there it develops and explains the Dirac equation and the spin-statistics theorem. For undergraduate and graduate educators and students in quantum theory courses as well as physicists working on quantum phenomena. Dover original publication.www.doverpublications.com Robert T. Deck has a PhD in Physics from the University of Notre Dame and is Emeritus Professor of Physics at the University of Toledo. He has written and co-written more than 50 papers for professional journals. This is his first book.