Before plunging into Peter Woit’s remarkable

*Not Even Wrong*it’s necessary to explain why this is the only book on the site that is unrated [NB - it was subsequently rated four stars from Michael Bycroft's review]. This is an assessment of just what is wrong with string theory/superstrings/M theory – but it would be unfair on the reader to describe it as a popular science book in the conventional sense. For much of the book, I’d suggest, you need a physics degree to be able to read it without really understanding it, but getting a gist of what’s going on (a bit like some of undergraduate lectures). To truly get the whole contents will probably require a postgraduate degree in physics or applied maths.
And yet… bits of it are tantalisingly good even without those qualifications. Woit provides a detailed explanation of how superstrings, M-theory et al – the only real attempt on the table at pulling together particle physics and gravity – came about. He also blisteringly tears apart what he suggests is perhaps not even science – the reason being that despite being around for over 20 years these theories are yet to make a single testable prediction. It really is stunning that these theories are given the attention they are. Woit makes a good case for this being down to the system. As it’s pretty well the only game in town, new particle physics have little choice but to go into it – and once in it, have committed too much time to head off in a totally new direction.

The worst part of the book is where Woit gives a detailed history of a range of particle accelerator projects, and his history of quantum mechanics is rushed and confusing, but there is much to learn in his assessment of the development of the standard model, and his description of where superstrings and M-theory came from.

So this is a hugely recommended book, but one that is extremely difficult to understand. The popular science audience is used to supporters of superstring/M-theory writing excited books that tell how wonderful these ideas are, without every bothering to point out they don’t actually have any connection with reality. It’s such a shame that Woit didn’t get a co-author who knows how to write for a general audience – or perhaps he can work with someone on a

*Not Even Wrong lite*. (Since writing this review,*The Trouble with Physics*was published, which fulfils that aim.) This is a story that needs to be widely told – and Woit has a powerful voice in doing so, which is why the content deserves 5 stars, but the complexity of the book makes it, as popular science, extremely low rated. Perhaps it was chickening out to leave it unrated, but I felt there was no other choice.Review by Brian Clegg

Believe it or not, back-flap endorsements can reveal something about the true content of a book. For example, the back cover of Not Even Wrong tells us that Roger Penrose found the book “compelling reading.” When a revered theoretical physicist finds a book stimulating, you might expect the average layperson to find it incomprehensible. In the case of Not Even Wrong, an attack on string theory backed by a history of mathematics and particle physics in 20th century, this is not far from the truth: about half in the pages in this book would be hard-going even for someone with an undergraduate degree in physics. But for a popular audience the book is saved by the care of Woit’s exposition, the clarity of his prose, and above all the strength and passion of his argument.

Before looking at the book’s content, it’s worth dwelling on it’s difficulty. Woit’s history of particle accelerators (at the start of the book) is approachable because it is rooted in concrete events, and his critique of string theory (at the end of the book) is easy on the reader insofar as it is about how science works rather than the science itself. But the science itself (the middle and longest part of the book) is really hard. And Woit has no wish to make it look easy. Here is a sample sentence from the middle chapters of the book:

“Just as Witten’s first topological quantum field theory did not actually tell topologists anything about Donaldson invariants that they did not already know, the topological sigma model also did not actually tell algebraic geometers anything about numbers of analytic fields that they did not already know.”

As hard as this sentence looks, however, it is written to be understood. Take away the technical terms in the sentence and it is written in the simplest possible English. Flick through the previous 10 pages and the technical terms in the sentence will all be explained in equally simple English. Go back to the start of the book and Woit says that there are two key things to know about quantum mechanics:

“1. There is a mathematical entity called a “state-vector” that describes the state of the universe at a given time. 2. Besides the state-vector, the other fundamental mathematical entity of the theory is called the Hamiltonian. This is an operator on state-vectors, meaning that it transforms a given state-vector into a new one.”

So, we have a state of the universe and something that changes the state. What could be simpler? Trace back the definitions of Woit’s many other terms — from mirror spaces, self-duality and Kac-Moody groups to non-abelian gauge theory, Lie Groups and heterotic superstring theory — and you will find them as simply described as the state-vector and the Hamiltonian. The care of Woit’s exposition means that although the book is dense, it is not impenetrable. I did not understand most of it, but with enough patience and concentration I am confident that I could do so. “Make things as easy as possible, but no easier,” to paraphrase Einstein. This is what Woit does — it just happens that his topic is not very easy.

For those (like me) who have low reserves of patience and concentration, the writing is well-enough sign-posted that one can understand the general landscape without scrutinising every detail. In his early chapter on the history and current prospects of particle accelerators (“Instruments of Production”), Woit guides the reader through the maze of particle accelerator acronyms, from CERN to SPLAC to SPEAR, SLAC, ISABELLE, and of course LHC. The next series of chapters are Woit’s efforts to set up a comparison between the “standard model” of particle physics and the alternatives to it. Readers who just want a good round of string theory fisticuffs could skip about half of this background. But for those want to learn about the complex interweaving of maths and physics since 1950, and about Woit’s two heros of that history (Hermann Weyl and Edward Witten), these chapters are worth the struggle.

At page 167, Woit changes gear. What follows is a sober, systematic assault on string theory and the ideas behind it. Despite the technical details, Woit says, “the hope is that the broad outlines of what is at issue here will remain clear to all readers.” Woit’s gift for clear summarising means that this hope is realised. In broad outline, the problem is that “string theory isn’t really a theory, but rather a set of reasons for hoping that a theory exists.” String theory can generate results, of a kind. These results have numerous gaps and errors that string theorists hope to fix. But attempts to fix them either result in baroque layers of new theory, or appeals to a semi-mystical theory called M-theory that no-one knows much about. And insofar as string theory gives a picture of particle physics, it gives us a choice between so many possible pictures that it explains nothing about why one particular picture is true.

Woit drives his case home in four persuasive ways. He describes typical ways of defending string theory (it is “beautiful”, the maths is very difficult, etc.) and attacks them. He discusses the scientific method and how string theorists abuse it (to his credit, Woit does more than just invoke Popper and falsifiability here; he also goes into the anthropic principle and acknowledges the value of speculative science). He gives an explanation, in terms of job markets and funding patterns in particle physics, of how string theory can have so little success as science yet so much popularity among scientists. And he gives evidence of intellectual rot in the string theory community, in an entertaining account of the “Bogdanov Affair,” the physicist’s version of the famous Sokal hoax. All this adds up to a devastating case.

Devastating, but cool, Woit’s steady prose is a challenge to the excitement surrounding string theory, the excitable physicists who practice it, and the excited books they write about it. Brian Greene’s books are “inspirational”, says Woit, but that’s just the problem: string theorists get carried away by their own excitement. Woit, despite his penchant for quotes, anecdotes, and quirky asides, may be the least excitable author in popular science.

Nevertheless, he is also one of the most passionate. The reason he builds up such a patient account of string theory is to show as clearly as possible why the whole field is a mistake. He sincerely believes his case and backs it up with a deep knowledge and appreciation of his subject matter. The book, like the introduction, has a personal touch. As a result, his first-hand accounts of mathematical heroics by Edward Witten and Sir Michael Atiyah convey as much excitement as any popular writer could with a more colourful reproduction of the same events. And his point-by-point rebuttal of string theorists has extra force because he is so concerned that their work is leading physics into disrepute. And he has a heart-felt (though not very precise) vision of what could replace the “ossified ideology” that string theory has, in his opinion, become: he invites string theorists to discover “that the marvellously rich interaction of quantum field theory and mathematics that has so revolutionised both subjects is just a beginning.”

Some points in the book could be clearer. On the one hand Woit criticises string theory for not actually being a theory. On the other hand he identifies some predictions that a supersymmetry theory can make, which suggests that supersymmetry at least is a theory (if not a very good one). Also, after giving the two main arguments for supersymmetry, Woit makes things hard for the reader by going into a long digression about a particular supersymmetry theory (MSSM) in which a number of other arguments and counterarguments appear. And the relation between supersymmetric quantum field theories and string theory is not very clear, so it is not obvious why string theory inherits the problems with supersymmetry (problems that Woit describes at length). Woit’s foray into the philosophy of science is also inconclusive – at one point he seems to say, despite himself, that string theory is still worth doing because the majority of particle theorists think it will be eventually bear fruit. Lastly, it would be interesting to know more about what Witten – who Woit clearly reveres – thought about string theory two decades after he fathered the field.

Overall, however, Woit’s passion means that the second back-flap endorsement on my copy of this book is as true as the first: the book is a “call to arms,” as

*New Scientist*put it. To write a book that Roger Penrose finds compelling is one thing, and to write a book that*New Scientist*finds rousing is another. But to do both with the same book is quite an achievement.Review by Michael Bycroft

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