Almost fifty years after he first crossed the small screen, Doctor Who remains a science fiction touchstone. His exploits are thrilling, his world is mind-boggling, and that time travel machine―known as the Tardis―is almost certainly an old-fashioned blue police box, once commonly found in London. Paul Parsons's plain-English account of the real science behind the fantastic universe portrayed in the Doctor Who television series provides answers to such burning questions as whether a sonic screwdriver is any use for putting up a shelf, how Cybermen make little Cybermen, where the toilets are in the Tardis, and much more. Taking the show as a starting point―episode-by-episode in some cases―Parsons dissects its scientific concepts. In addition to explaining why time travel is possible and just how that blue police box works, Parsons • discusses who the Time Lords are and how we may one day be able to regenerate just like them • ponders the ways that the doctor's two hearts might work and introduces us to a terrestrial animal with five • details the alien populations and cosmology of the Whovian Universe and relates them to what we currently know about our universe • compares the robotics of the show with startlingly similar real-world applications This slender, equation-free discussion is penned by a Ph.D. cosmologist and is ideal beach reading for anyone who loves science and watches the show―no matter which planet the beach is on.