Sean Carroll in Preposterous Universe:
For decades now physicists have been struggling to reconcile two great ideas from a century ago: general relativity and quantum mechanics. We don’t yet know the final answer, but the journey has taken us to some amazing places. A leader in this quest has been Leonard Susskind, who has helped illuminate some of the most mind-blowing ideas in quantum gravity: the holographic principle, the string theory landscape, black-hole complementarity, and others. He has also become celebrated as a writer, speaker, and expositor of mind-blowing ideas. We talk about black holes, quantum mechanics, and the most exciting new directions in quantum gravity.