This is the story of the greatest puzzle in our universe: what is light? Light Years is an engaging survey of everything we know of the universes most enigmatic phenomenon and the remarkable people who have been captivated by it. Light Years looks over the shoulders of the great revolutionaries of light theory--Bacon, Galileo, Newton, Faraday, Maxwell and Feynman--and tra This is the story of the greatest puzzle in our universe: what is light? Light Years is an engaging survey of everything we know of the universes most enigmatic phenomenon and the remarkable people who have been captivated by it. Light Years looks over the shoulders of the great revolutionaries of light theory--Bacon, Galileo, Newton, Faraday, Maxwell and Feynman--and traces the evolution of light-driven devices from the camera to the laser. In this revised edition, leading popular science author Brian Clegg reveals how twenty-first century scientists have achieved the seemingly impossible in bringing light to a halt, and used the quantum properties of entangled light to produce unbreakable encryption and unbelievable computers. He explains the mind-bending advances that put light at the heart of all matter and which could finally make time travel possible.