ABSTRACT
Although for many years the story of string theory had been viewed as an attempt to construct a fundamental theory of nature, few now see it solely in this light. The year on which this story pivots is 1997. Up until then, string theory was broadly felt to belong on the top floor of an intellectual tower. Its practitioners regarded it as inhabiting the penthouse suite of ideas: above quantum mechanics, above general relativity and above quantum field theory. Quantum field theory was regarded as something that arose in certain limits of string theory when stringy effects were removed. The converse was not true – strings, and quantum gravity, did not arise from limits of quantum field theory. Indeed, even classical gravity was absent from quantum field theory. The relationship of string theory to quantum field theory was like quantum mechanics to classical mechanics – an upgrade that, while backwards compatible, also added many new features.
