Instead, it is a philosopher's attempt to identify and localize, name, summarize, articulate, and present the reasons why string theory could have become the definition of status quo in the state-of-the-art theoretical physics despite the fact that the most natural conditions that string theory has something "new and direct" to say about seem to be inaccessible far from the currently doable experiments.
For this reason and others, the book was endorsed by big shots such as John Schwarz and David Gross.
The expensive yet short, 210-page-long book is divided to 7 chapters. The first one is an extended introduction to string theory (technical; sociology of non-experts talking about string theory; three contextual arguments in favor of ST); the second one is on the general conceptual framework of physical theories; next one on underdetermination applied to string theory (including some Bayesian reasoning); dynamics in high-energy physics; underdetermination in physics and beyond; whether or not one may claim that ST is a final theory; changes proposed for "scientific realism".
In the segments about sociology, the author describes both the near-certainty of the practitioners about string theory's validity; as well as the cynicism by many of the non-experts. The more stupid and ignorant you are, the more cynical about string theory – the unifying pillar of the 21st century physics – you may become. The cynics appear in various adjacent, next-to-adjacent, and unrelated disciplines – despite the fact that, as Dawid points out, string theory has helped to transform the way how people think and talk about pretty much all of theoretical physics and all of high-energy physics.
The three reasons behind the near-certainty about the theory's validity are:
- the non-existence of alternatives
- the surprising emergence of coherent explanations within string theory
- extrapolation of the previous successes in high-energy physics: the Standard Model was also conceived because of largely theoretical reasons, had no alternatives, led to a nontrivial, surprisingly consistent unification of our descriptions of many things, and therefore had to be right
It is easy to misunderstand – and deliberately obfuscate – these facts. There exist "trademarks" that are marketed as competitors of string theory. But nothing really works over there. There exist no signs that these theories are on the right track. The people associated with these directions know that but some of them try to mislead the laymen about these facts. Some of them simply want to help themselves personally; others may be less egotist but they want a "greater diversity of ideas" than what the available evidence suggests as the right degree of diversity. And yet another group is just incompetent.
Concerning the second argument, it is a theoretical argument but a very powerful one. If string theory were a wrong theory of Nature, one would have no explanation why it has taught us about so many mechanisms that unify previously different concepts in physics and that retain their complete consistency, despite all kinds of a diseases that would have surely killed a generic wrong theory many times. The deep association between string theory and the laws that everything in the Universe obeys seems to be the only explanation of this coherence and unifying power, the ability to produce unexpected links, relationships, and transitions while avoiding any inconsistency.
Of course, one could argue that string theory is this coherent, powerful, and "willing to teach us" because of a different reason: it could be just a coherent mathematical structure that doesn't form the skeleton of the foundations of physics. If you wish, it could be the Devil who is constantly tempting us rather than God. But such an alternative theory would apparently predict that there will already be a demonstrable incompatibility between the highly constraining principles of string theory and some of the numerous (understatement!) insights we have already learned about the physical Universe. There aren't any inconsistencies of this kind, either: at least as the first sketch, string theory agrees with all the general features (types of fields and interactions etc.) we know from particle physics and cosmology. There's a lot of evidence that string theory is both very deep and very physical.
The last argument is probably a good way to describe the actual reason why I disagree with the suggestions elsewhere in the book that one needs to redefine the scientific method or do similar things. It seems obvious to me that the reasons that make string theorists near-certain that string theory is the right description of Nature have been used by physicists at least for 50 years and, in some respects, much longer than that.
Around 1974, string theory was identified as a candidate theory of quantum gravity – the only consistent one in \(d=4\) or higher so far. This already implies that its characteristic effects in which it shows its muscles in their full glory can't be directly measured in the experiments (already Max Planck was able to calculate that the Planck length was \(10^{-35}\) meters or so). I knew this was almost certainly the case when I was 10 years old or so. This inaccessibility by direct experiments is a defining feature of any theory of quantum gravity. Despite this knowledge, I wasn't repelled by string theory. If we can't "touch" something, it doesn't mean that we can't scientifically study it. Atoms became a part of science well before people "saw" them (because of the mixing ratios in chemistry and many other reasons). Physics of the 20th century brought us many more examples like that. Physics is really working like that most of the time today! When I was 10, I didn't know that almost 30 years later, a new kind of Inquisition would hysterically try to prevent people from applying the scientific method to energy scales that can't be directly tested.
String theory is really using the same kind of thinking about the possible deeper levels of explanation that were employed – and turned out to be successful – in the advances associated with quantum field theory. Any criticism of these argumentative patterns seems totally unjustifiable to me: it's really the only way how to think about these matters scientifically. The only plausible alternative is not to think about the unification in physics and the fundamental scale at all. I just think that the mankind would become a horde of uncultural barbarian apes if it decided it doesn't want to think about these issues – if it wanted to prevent a fraction of its intellectual resources from thinking about these fundamental issues.
Some people love revolutions and permanent revolutions. Am I among them? It depends on what you mean a revolution. I surely oppose any attempt to replace rational arguments in science by irrational ones (e.g. ad hominem ones or slogans that have nothing to do with the actual technical research); or to "ban" any kind of an argument that is obviously rational. Every solid enough argument and line of reasoning or inference, however indirect, should be used when we are forming our opinions about scientific questions. When this is done correctly in the case of fundamental physics, we reach a near-certainty that string theory is a valid (and probably the final) theory of Nature. It's possible despite the experimental inaccessibility of the Planck scale because direct experiments are very far from being the only tool how we are learning the truth about physics in the 20th and 21st century.
If you prefer the cheaper books by crackpots, you may buy books by Faggott (early August) and Unzicker (late July) instead.
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