The story of physicists' quest to answer a mind-boggling question: How can we travel through time? Since H.G. Wellsʾs 1895 classic The Time Machine, readers of science fiction have puzzled over the paradoxes of time travel. But in the 1990s, a group of theoretical physicists at Caltech undertook a serious investigation of the possibility of pastward time travel and concluded that it might be possible, inspiring a serious and sustained study that engaged more than thirty physicists around the world. Many of the figures involved in these theories are familiar: Einstein, Stephen Hawking, and Kip Thorne; others are names known mostly to physicists. These are the new time travelers, and this is the story of their work--a profoundly human endeavo...