Turning Points in Physics is a series of 1958 lectures presented at the Oxford University in Trinity Term. This six-chapter book highlights the interplay between assumptions, theories, and experimental discoveries in physics. The first chapter provides a brief introduction to the physical theory and field physics. The following two chapters cover the basic principles of quantum nature of matter and radiation, as well as the introduction of the probability concept in the field physics. The discussion then shifts to the theory of relativity and the fundamentals of cause and effect. The last chap