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Three decades ago, Stephen Hawking famously declared that a "theory of everything" was on the horizon, with a 50 per cent chance of its completion by 2000. Now it is 2010, and Hawking has given up. But it is not his fault, he says: there may not be a final theory to discover after all. No matter; he can explain the riddles of existence without it.

The Grand Design, written with Leonard Mlodinow, is Hawking's first popular book in almost a decade. It duly covers the growth of modern physics (quantum mechanics, general relativity, modern cosmology) sprinkled with the wild speculation about multiple universes that seems mandatory in popular works these days. Short but engaging and packed with colourful illustrations, the book is a natural choice for someone wanting a quick introduction to mind-bending theoretical physics.

Early on, the authors claim that they will be answering the ultimate riddles of existence - and that their answer won't be "42". Their starting point for this bold cla