"Posing simple, fundamental questions such as, 'Why do we exist?' the authors employ word pictures, analogies to everyday experience, but (blessedly) no equations to convey the physics that are involved in the answer this book ultimately offers. Sympathetically noting that quantum mechanics and general relativity remain as counterintuitive to experts as to laypeople, Hawking and Mlodinow alight on the probabilistic nature of energy and matter, frames of reference, string theory, and the incredibly finely-tuned values of physical forces and masses that permit life to exist, combining their presentations into the propositions of 'M-theory' about what initiated the big bang."—Booklist