This work covers the philosophical heart of the issues of space and time. It introduces the revolutionary ideas of Einstein, along with the concepts and arguments of philosophers, both ancient and modern, which have proved of lasting value. The text serves to introduce the subject for beginning students as well as provide a clear statement of the "state of the debate" for a popular science readership. Topics include Einstein´s special and general relativity, how to build an atom bomb, the four-dimensional universe, the possibility of time travel, the impossibility of motion, whether space curves, the big bang, black holes, as well as an inflationary and accelerating universe.