Mathematician Kurt Godel is widely regarded for his 1931 incompleteness theorem, which found that not everything can be proved. Godel then turned his attention to time, a subject that he mulled over with his good friend and sometimes foil Albert Einstein, In 1949, Godel postulated a theorem that stated, "In any universe described by the theory of relativity, time cannot exist." The premise centers on the idea that if a spaceship goes fast enough, it can travel through the past, present, and future. If we can revisit the past, asserted Godel, then it never really passed. But a time that fails to pass is no time at all. Einstein was never able to refute Godel's idea. Yourgrau reports that no one else has done so, either, though, he acknowledges, few have tried. Although Godel's idea has been largely disregarded, Stephen Hawking has attempted to disprove it through his "chronology-protection conjecture." Yourgrau asserts that Godel was a truly subversive thinker, far ahead of his, and perhaps current, time, The author considers the validity of Gddel's idea and argues that mathematicians and physicists alike should revisit Godel's theorem. In doing so, the author provides fascinating insight about Godel's relationship with Einstein and how this contentious idea challenged and inspired them both.