Physicists have been exploring, debating, and questioning the general theory of relativity ever since Albert Einstein first presented it in 1915. In this sweeping narrative of science and culture, astrophysicist Pedro Ferreira brings general relativity to life through the story of the brilliant physicists, mathematicians, and astronomers who have taken up its challenge. Over the course of a century, their studies of general relativity have delivered key insights into our understanding of the origin of time and the evolution of all the stars and galaxies in the cosmos. Now, as scientists look farther and more clearly into space than ever before, The Perfect Theory reveals the greater relevance of general relativity, showing us where it started, where it has led, and where it can still take us.