Quantum theory is one of the great achievements of twentieth century physics. Born at the very beginning of the century, it attained a definitive form by 1932, yet continued to evolve throughout the century. Its applications remain fully a part of modern life. It should thus come as no surprise that literature on the history of quantum theory is vast, but author Robert D. Purrington approaches the story from a new angle, by examining the original physics papers and scientific studies from before the creation of quantum mechanics to how scientists think about and discuss the subject today. The Heroic Age presents for the first time a detailed but compact and manageable history of the creation of quantum theory, and shows precisely where each important idea originated. Purrington provides the history of the crucial developmental years of quantum theory with an emphasis on the literature rather than an overview of this period focusing on personalities or personal stories of the scientists involved. This book instead focuses on how the theoretical discoveries came about, when and where they were published, and how they became accepted as part of the scientific canon.