Book Review: “Why String Theory?” by Joseph Conlon

Why String Theory?
By Joseph Conlon
CRC Press (November 24, 2015)

I was sure I’d hate the book. Let me explain.

I often hear people speak about the “marketplace of ideas” as if science was a trade show where researchers sell their work. But science isn’t about manufacturing and selling products, it’s about understanding nature. And the sine qua non for evaluating the promise of an idea is objectivity.

In my mind, therefore, the absolutely last thing that scientists should engage in is marketing. Marketing, advertising, and product promotion are commercial tactics with the very purpose of affecting their targets’ objectivity. These tactics shouldn’t have any place in science.

Consequently, I have mixed feelings about scientists who attempt to convince the public that their research area is promising, with the implicit or explicit goal of securing funding and attracting students. It’s not that I have a problem with scientists who write for the public in general – I have a problem with scientists who pass off their personal opinion as fact, often supporting their conviction by quoting the number of people who share their beliefs.

In the last two decades this procedure has created an absolutely astonishing amount of so-called “science” books about string theory, supersymmetry, the multiverse and other fantasies (note careful chosen placement of commata), with no other purpose than asking the reader to please continue funding fruitless avenues of research by appealing to lofty ideals like elegance and beauty.

And indeed, Conlon starts with dedicating the book to “the taxpayers of the UK without whom this book could never have been written” and then states explicitly that his goal is to win the favor of taxpayers:

“I want to explain, to my wonderful fellow citizens who support scientific research through their taxes, why string theory is so popular, and why, despite the lack of direct empirical support, it has attained the level of prominence it has.”

That’s on page six. The prospect of reading 250 pages filled with a string theorists’ attempt to lick butts of his “wonderful fellow citizens” made me feel somewhat nauseous. I put the book aside and instead read Sean Carroll’s new book. After that I felt slightly better and made a second attempt at Why String Theory?

Once I got past the first chapter, however, the book got markedly better. Conlon keeps the introduction to basic physics (relativity and quantum theory) to an absolute minimum. After this he lays out the history of string theory, with its many twists and turns, and explains how much string theorists’ understanding of the approach has changed within the decades.

He then gets to the reasons why people work on string theory. The first reason he lists is a chapter titled “Direct Experimental Evidence for String Theory” which consists of the single sentence “There is no direct experimental evidence for string theory.” At first, I thought that he might have wanted to point out that string theorists work on it despite the lack of evidence, but that the previous paragraph accidentally made it look as if he, rather cynically, wanted to say that the absence of evidence is the main reason they work on it.

But actually he returns to this point later in the book (in section 10.5), where he addresses “objections made concerning connection to experiment” and points out very clearly that even though these are prevalent, he thinks these deserve little or no sympathy. This makes me think, maybe he indeed wanted to say that he suspects the main reason so many people work on string theory is because there’s no evidence for it. Especially the objection that it is “too early” to seek experimental support for string theory because the theory is not fully understood he responds to with:

“The problem with this objection is that it is a time-invariant statement. It was made thirty years ago, it was made twenty years ago, it was made a decade ago, and it is made now. It is also, by observation, an objection made by those who are uninterested in observation. Muscles that are never used waste away. It is like never commencing a journey because one is always waiting for better modes of transportation, and in the end produces a community of scientists where the language of measurement and experiment is one that may be read but cannot be spoken.”

Conlon writes that he himself isn’t particularly interested in quantum gravity. His own research is finding evidence for moduli fields in cosmology, and he has a chapter about this. He lists the usual arguments in favor of string theory, that it connects well to both general relativity and the standard model, that it’s been helpful in deriving some math theorems, and that now there is the AdS/CFT duality by help of which one might maybe one day be able to describe some aspect of the real world.

He somehow forgets to mention that the AdS/CFT predictions for heavy ion collisions at the LHC turned out to be dramatically wrong, and by now very few people think that the duality is of much use in this area. I actually suspect he just plainly didn’t know this. It’s not something that string theorists like to talk about. This omission is my major point of criticism. The rest of the book seems a quite balanced account, and he restrains from making cheap arguments of the type that the theory must be right because a thousand people with brains can’t be mistaken. Conlon even has a subsection addressing Witten-cult, which is rather scathing, and a hit on Arkani-Hamed gathering 5000 citations and a $3 million price for proposing large extra dimensions (an idea that was quietly buried after the LHC ruled it out).

At the end of the book Conlon has a chapter addressing explicit criticisms – he manages to remain remarkably neutral and polite – and a “fun” chapter in which he lists different styles of doing research. Maybe there’s something wrong with my sense of humor but I didn’t find it much fun. It’s more like he is converting Kuhn’s phases of “normal science” and “revolution” into personal profiles, trying to reassure students that they don’t need to quantize gravity to get tenure.

Leaving aside Conlon’s fondness of mixing up sometimes rather odd metaphors (“quantum mechanics is a jealous theory... it has spread through the population of scientific theories like a successful mutation” – “The anthropic landscape... represents incontinence of speculation joined to constipation of experiment.” – “quantum field theorists became drunk on the new wine of string theory”) and an overuse of unnecessary loanwords (in pectore, pons asinorum, affaire de coer, lebensraum, mirabile dictum, for just to mention a few), the book is reasonably well written. The reference list isn’t too extensive. This is to say in the couple of cases in which I wanted to look up a reference it wasn’t listed, and the one case I wanted to check a quotation it didn’t have an original source.

Altogether, Why String Theory? gives the reader a mostly fair and balanced account of string theory, and a pretty good impression for just how much the field has changed since Brian Greene’s Elegant Universe. I looked up something in Greene’s book the other day, and found him complaining that the standard model is “too flexible.” Oh, yes, things have changed a lot since. I doubt it’s a complaint any string theorist dare raise today.

In the end, I didn’t hate Conlon’s book. Maybe I’m getting older, or maybe I’m getting wiser, or maybe I’m just not capable of hating books.

[Disclaimer: Free review copy.]

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Win a copy of Why String Theory by Joseph Conlon!

I had bought the book before I was sent the review copy, and so I have a second copy of the book, entirely new and untouched. You can win the book if you are the first to answer this question correctly: Who was second author on the first paper to point out that some types of neutrino detectors might also be used to directly detect certain candidate particles for dark matter? Submit answer in the comments, do not send an email. The time-stamp of the comment counts. (Please only submit an answer if you are willing to send me a postal address to which the book can be shipped.)

Update: The book is gone!