This book is now fully updated, with a new chapter, covering the thrilling developments in light science of the past five years...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 universe's most enigmatic phenomenon and the remarkable people who have been captivated by it. It takes us from the spiritual interpretations of Neolithic worshippers, Ancient Egyptians and the Mayans, through the Impressionists' love affair with light, to Einstein's shattering conclusions. "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. Uniquely 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.