The first comprehensive philosophical and historical account of the experimental foundations of Niels Bohr’s practice of physics. Niels Bohr was a central figure in quantum physics, well known for his work on atomic structure and his contributions to the Copenhagen interpretation of quantum mechanics. In this book, philosopher of science Slobodan Perović explores the way Bohr practiced and understood physics and analyzes its implications for our understanding of modern science. Perović develops a novel approach to Bohr’s understanding of physics and his method of inquiry, presenting an exploratory symbiosis of historical and philosophical analysis that uncovers the key aspects of Bohr’s philosophical vision of physics within a given historical context. To better understand the methods that produced Bohr’s breakthrough results in quantum phenomena, Perović clarifies the nature of Bohr’s engagement with the experimental side of physics and lays out the basic distinctions and concepts that characterize his approach. Rich and insightful, Perović’s take on the early history of quantum mechanics and its methodological ramifications sheds vital new light on one of the key figures of modern physics.