In the early Twentieth Century, new experimental evidence encouraged physicists to abandon a consistent and nearly complete description of nature. They replaced common sense notions about the physical world with strange realities based on the new theories of relativity and quantum mechanics. As the physicists' new explanations of nature grew increasingly counter-intuitive, it became harder for non-physicists to understand precisely what physicists where doing. Without using higher mathematics, this course explores quantum mechanics and relativity as they describe the nature of matter and energy and the structure of space and time. It also addresses how physicists struggled to understand the philosophical implications of the new physical theories, how they worked to express their strange descriptions of nature to both public and professional audiences, and how they maintained public support for their increasingly expensive explorations of nature.