Dn this book, Stephen Hawking exposes the discoveries of astrophysicists. Retracing the great theories of the cosmos from Galileo to Einstein, recounting the ultimate discoveries in cosmology, explaining the nature of black holes, he then proposes to take up the greatest challenge of modern science: The search for a theory making it possible to reconcile general relativity and quantum mechanics. Stephen Hawking has been battling a very serious neurological disease for more than twenty years. Despite this handicap, he devoted his life to trying to unlock the secrets of the universe and to share his discoveries with us.