During the last few decades ambitious theories of fundamental physics with little or no connection to experiment have been strongly criticized from a methodological point of view. Objections to string theory, supersymmetry, many-worlds quantum mechanics, multiverse theories, and the anthropic principle come from within the physics community as well as outside it. The best known example of the genre may be Peter Woit's best-selling Not Even Wrong from 2006, which specifically was aimed against the theory of superstrings. British science writer Jim Baggott likewise argues that many ideas of modern theoretical physics are so bizarre and remote from empirical reality that they hardly qualify as science. As he points out, this kind of “fairy-tale physics” sells very well to the wider public, often in books with titles and subtitles that grossly misrepresent what the books are really about. I can't help feeling that this is also the case with Baggott's book, the title of which is quite misleading. Readers will soon discover that it is not really a polemical book on how physics has said “farewell to reality” and “betrayed the search for scientific truth.” No, the book is primarily a solid, accurate, and well-written popular history of branches of modern theoretical physics. Baggott does criticize some of these highly publicized theories, charging that they are untestable and methodologically unsound, but his critique is throughout balanced and well informed. For example, although he generally favors empiricism and insists on testability, he also stresses that there are no empirical facts without theory, and he recognizes that testability is not a simple concept. There must be some empirical evidence for the predictions of a theory, but does the evidence need to be direct? If not, how indirect can it be? Is it enough that a theory is testable in principle, or does it need to be actually testable? Even if a theory is not testable at present, perhaps it will be so in a future version—but then, how long should we wait?
Farewell to Reality consists of three parts of which the first is a condensed discussion of relevant concepts in the philosophy of science that Baggott summarizes in a number of “principles.” Although he speaks of the scientific method, he is well aware that there is no single methodological formula that encompasses all of science. And although he tends to associate scientific truth with the correspondence criterion of truth, he realizes that in some cases (say string theory and black hole physics) the coherence criterion comes closer to scientific practice. In general, Baggott's principles of science are sensible and fairly conventional, of the kind that the large majority of physicists will have no problem accepting. The second part of the book is a semi-historical account of modern theoretical physics and cosmology, from special relativity and early quantum theory to the Higgs boson and dark energy. Although brief, the account is informative and covers many of the discoveries made in fundamental physics during more than a century. I found very few errors, among them the description of Dutch physicist Paul Ehrenfest as an Austrian. The more critical part of the book focuses on concepts and theories that are not (yet?) parts of the generally accepted world view, such as supersymmetry, grand unification, superstrings, multiverse, the holographic principle, and the anthropic principle. Baggott generally and sensibly objects that theories of this kind are not testable in the ordinary sense and, for this and other reasons, may perhaps better be characterized as metaphysics than physics. Not that he has any problem with scientists speculating, for speculations sometimes push the frontiers of science. “But when their ambition to give answers drives them to tell fairy tales, smothered in a sugar-coating of anthropic logic, let us all be clear that we've left science far behind” (p. 283). It all boils down to what we mean by science. There are currently proposals from some physicists to change the rules of the game in order to accommodate within science new areas of academic discourse. Baggott follows other critics in pointing out the problematic and perhaps even devastating consequences that such an extension of the basic criteria of science may have.
But how important is the problem? After all, if scientific truth has been betrayed it is not by “modern physics” but only by a small segment of it. So why not let the few theorists cultivating fairy-tale physics continue to ply their trade? At least it is entertaining. Baggott argues that the problem is potentially serious, especially in the public sphere where it may erode the credibility and epistemic authority of the scientific community. Perhaps he is right, but it should be kept in mind that fairy-tale science is not a modern phenomenon and that previous instances of the phenomenon have not caused any real harm. Baggott's book deals rather narrowly with modern fundamental physics. A broader framework in both a chronological and disciplinary sense would have been an advantage, for only then can the significance of current fairy-tale physics be properly evaluated.
Helge Kragh is a Professor of History of Science at Aarhus University, Denmark. He works on the history of modern cosmology and physical sciences. He has written extensively on the history of physics; his most recent books are Higher Speculations: Grand Theories and Failed Revolutions in Physics and Cosmology (2011), Niels Bohr and the Quantum Atom (2012), and Masters of the Universe: Conversations with Cosmologists of the Past (2014).
