Immanuel Kant's admiration of the "starry sky" above him and the "moral law" in it has become a philosophical topos today. While the "moral law" is the subject of practical philosophy, Kant refers to an object of astronomy for the main task of theoretical philosophy - namely, to answer the question "What can I know? ". Volume III tackles this question - generalizing to the "hard" sciences of physics, chemistry, and cosmology. It focuses on specific questions that have always been considered "philosophical" in the broadest sense by the interested public and even among physicists themselves: "What is simultaneity at different places?", "Which interpretation of quantum mechanics is the correct one and what follows from it for our view of the world?" - and, last but not least, "Did the universe exist from eternity or does it have a beginning (and an end)?".