Ours is the best of all possible worlds, according to Gottfried Leibniz at least, who reasoned that an omnipotent, omniscient God, having surveyed these possibilities, and being inherently good, can only have chosen the best one available to us. But still, it’s not perfect. Even knowing this world may be the best one possible, wouldn’t you, given the chance, go back in time and kill baby Hitler? Despite the wide variety of ethical, philosophical, and scientific questions raised by the possibility of time travel, and despite the wide range of literature, film, and scientific discussion on the topic, this simple poser has become the default encapsulation of everything about time travel: Given the technology, would you go back in time to eliminate someone we all can agree is universally evil?

The Kill Baby Hitler Conundrum was first postulated back in 1941, before the full reach of the Third Reich’s devastation was truly understood. In July of that year, Roger Sherman Hoar published the short story “I Killed Hitler” in Weird Tales under the pseudonym Ralph Milne Farley. In the story, an American painter called up for the draft goes back in time to kill a young Hitler. (In the story, the dictator is eleven—not a baby, but close enough). Time travel being what it is, things don’t work out quite as expected. By the end of the story, Hitler’s assassin has himself, through a series of twists and turns, assumed the dictator’s place. You can violate the laws of space and time, it seems, but you can’t escape the Law of Unintended Consequences.

Hoar’s story is just one of many time travel narratives chronicled in James Gleick’s new book, Time Travel, a survey of the various ways we’ve schemed and dreamed to overtake the ticking clock, readjusting the past and altering the future to imagine better worlds and better times. “Why do we need time travel, when we already travel through space so far and fast?” he asks. “For history. For mystery. For nostalgia. For hope. To examine our potential and explore our memories. To counter regret for the life we lived, the only life, one dimension, beginning to end.”

Gleick’s first two books were relatively straightforward biographies: One on theoretical physicist Richard Feynman, the other on the concept of chaos. His third book, Faster (1999) was, well, faster—offering a series of vignettes that slammed the reader in rapid-fire succession, enumerating a thousand different ways in which modern life has sped up time in the futile promise that we might “save” it. Time-saving conveniences, he argues, are a false messiah, the byproducts of a delusion that pushes us to consume at an ever-faster rate without offering much by way of meaningful benefit. His next book, The Information (2011), was something of a return to an earlier, slower-paced mode of storytelling, with generous chapter lengths recounting the unexpected ways in which we’ve accumulated and transmitted data through the centuries. With Time Travel, Gleick has returned again to the form of Faster, and at times it almost feels like a sequel to that earlier work, or at least a continuation on a theme. If Faster probed why we’re so obsessed with speeding up time, Time Travel asks why we’re equally obsessed with transcending it altogether.

As a time machine, Gleick’s narrative rarely proceeds chronologically, opting instead to bounce from topic to topic, back and forth along multiple axes, guided in many ways by the twin lights of H. G. Wells and Albert Einstein. Faster focused on psychology and sociology, but most of all with technology, marketing, and consumerism. How innovations promised to save us time and failed, and how marketing helped create a perpetual sense in us that we’re lagging behind. Time Travel turns instead largely to fiction (where, of course, most time travel actually happens) and physics (where it has been most strenuously explored and debated as a serious concept).