This book comes with an introduction by Philip Pullman. Award-winning science writers Mary and John Gribbin reveal how Pullman's His Dark Materials trilogy (Northern Lights, The Subtle Knife and The Amber Spyglass) is rooted in astonishing scientific truth. Drawing on string theory and spacetime, quantum physics and chaos theory, they answer fascinating questions such as: could parallel worlds like Will's and Lyra's really exist? How does the subtle knife cut through anything? Could there be a bomb like the one made with Lyra's hair? And, of course, What are the dark materials?