He quotes Edward Witten, but Witten made his comments in a very different context-and three years after the discovery of accelerating expansion. Although his book is for the most part thoroughly referenced, Smolin cites no source on this point. Even the turning point, the first crack in the facade, is based on a myth: Smolin claims that string theorists had predicted that the energy of the vacuum-something often called dark energy-could not be positive and that the surprising 1998 discovery of the accelerating expansion of the universe (which implies the existence of positive dark energy) caused a hasty retreat. But this story, however grippingly told, is more a work of drama than of history. He accurately captures the excitement that theorists felt at the discovery of this unexpected and powerful new idea. Smolin presents the rise and fall of string theory as a morality play. What is worse, they contend, too many theorists continue to focus their efforts on this idea, monopolizing valuable scientific resources that should be shifted in more promising directions. Today, after more than 20 years of concentrated effort, what has been accomplished? What has string theory predicted? Lee Smolin, in The Trouble with Physics, and Peter Woit, in Not Even Wrong, argue that string theory has largely failed. Rather suddenly, the attention of many of those working on unification shifted to string theory, and there it has stayed since. The Standard Model is a quantum field theory, in which particles behave as mathematical points, but a small group of theorists explored the possibility that under enough magnification, particles would prove to be oscillating loops or strands of "string." Although this seemingly odd idea attracted little attention at first, by 1984 it had become apparent that this approach was able to solve some key problems that otherwise seemed insurmountable. Some investigators even sought to unify gravity with the other three forces and to resolve the problems that arise when gravity is combined with quantum theory.
Fresh from this success, they turned to the problem of finding a unified theory, a single principle that would account for all three of these forces and the properties of the various subatomic particles. After decades of effort, theoretical physicists had come to understand the weak and strong nuclear forces and had combined them with the electromagnetic force in the so-called Standard Model. The 1970s were an exhilarating time in particle physics. Not Even Wrong: The Failure of String Theory and the Search for Unity in Physical Law. The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next.
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