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Stephen Hawking is a theoretical physicist and cosmologist, whose scientific books and public appearances have made him an academic celebrity. He is known for his contributions to the fields of cosmology and quantum gravity, especially in the context of black holes. He has also achieved success with works of popular science in which he discusses his own theories and cosmology in general. John Preskill is the Richard P. Feynman Professor of Theoretical Physics, and Director of the Institute for Quantum In
