Stanford University physicist Leonard Susskind revels in discovering ideas that transform the status quo in physics. Forty years ago he co-founded string theory, which was initially derided but eventually became the leading candidate for a unified theory of nature. For years he disputed Stephen Hawking’s conjecture that black holes do not merely swallow objects but grind them up beyond recovery, in violation of quantum mechanics. Hawking eventually conceded. And he helped to develop the modern conception of parallel universes, based on what he dubbed the “landscape” of string theory. It spoiled physicists’ dream to explain the universe as the unique outcome of basic principles.