Ye Olde Natural Philosophy Discussion Group

Reviews and comments on
Lee Smolin:
The Trouble With Physics: The Rise of String Theory, the Fall
of a Science, and What Comes Next

One of our members (Ron) has a young son (Ian)
who is just learning to tie his shoes. When Ian saw
the cover of this book he exclaimed, “Dad! You’ve
bought me a book on how to tie my shoes!” Alas,
string theory seems to be not nearly so useful!

      Our group as a whole had sort of a medium appraisal of this book. Two members, Rich and John, thought very highly of it and gave it a rating of 8 (on a scale of 0 to 10), but the rest of us gave it lower ratings, and the group average came out at 5.5. Kirby missed the session, but sent in the following comments via email:

      I read a little more than half the book. I keep going back and forth between a 5 and a 6. Quite frankly, the more I read, the more lost I became. Partly that is a function of my inability to comprehend physics, but I also think the book is very poorly written and/or edited. Case in point: On page 127 he writes “String theory would not be one theory, it would be a landscape of theories...” and then on 128 “All we had was a list of hundreds of thousands of distinct theories, each with many free constants.” Then, next page, next chapter, he says “the five consistent superstring theories in ten-dimensional spacetime...” and then all of a sudden, it seems to me, he has become concerned only with those five theories. It seemed to me that this was a very sudden, and very poorly done, transition in less than a page from hundreds of thousands of theories, to 5. Of course, I was already lost by that time, so I might have forgotten how or why he could do that. I did scan back a ways in the book, trying to see where he set that transition up, but I didn’t find it. That wasn’t the only time I think the book seemed disjointed, but I’ll skip other examples since I am not even there to discuss them.

      He probably does do a good job of explaining where string theory stands and how it got there. I think he started well, and I understood the basics through about the first quarter or third of the book, but once you miss a concept, it goes down hill fast. I hope you all understood it better than I did. You can explain it to me sometime!

      I think I will settle on a 5 for this book. We have read better books (or maybe just one book?) on string theory. Anyway, I understood it better before I read this book—I think!! I don’t think he had to go into quite all that detail, if his main purpose was to point out the flaws in the theory. I’m assuming that was his purpose, from the title. Since I didn’t finish it, you guys can tell me what the conclusion was. I just didn’t enjoy the book at all. I give it a 5 only because I am giving him the benefit of the doubt that maybe he wrote it well, and I just wasn’t into it.

      However, Kirby’s comments struck a chord with many others of us as well. Ron thought that Smolin started out great, but that he got into string theory in way too much detail. He believes Smolin felt he had to do that because he had to show he appreciated string theory and its accomplishments before he went on to criticize its shortcomings. Kevin S. also said he hated the way the book was edited, and how it jumped from one place to another. He kept asking himself, “How did he get there?” Rosie, although she enjoyed the very first part of the book (and especially where Smolin laid out the five main problems for physics today), thought that overall “the writing was so poor I had no desire to read the rest of the book.”

      Scott didn’t object to the considerable detail, just to the fact that quite a bit of that detail was semi-incomprehensible to him, especially parts of chapter 9 on the second superstring “revolution”. Scott refers specifically to “M-theory” (which is supposedly not really a theory but some sort of half-baked metatheory), Maldacena’s conjecture about a new kind of “duality”, and stuff like that. Smolin says that “Maldacena’s revolutionary idea was that a string theory could have a dual description in terms of a gauge theory.” Let’s see now, just what is a gauge theory again? Yes, Smolin talked about that earlier, but not in a way that was fully comprehensible to me.1   Here Scott has to echo again a point made by Kirby: once you don’t really understand one key concept, things are all downhill from there.

      Barbara asked

“What is all this stuff about quantum theory, relativity, etc.? I don’t even know what string theory is! I don’t see the common sense of it. I had no idea what he is saying.”

      This gets into another question raised by a number of people, as to just which audience this book was directed at. It appears that in general it was intended to be a book popularizing string theory and its limitations (so far) for a general audience of educated, intelligent people who are interested in science. I think our group fits that description pretty well. If a number of us have trouble with a book, then it seems fair to say that at least some of the explanations were not adequate for such an audience. Many of us think that the book actually had three different intended audiences: the interested public, physicists themselves, and university administrators and those otherwise involved in funding, directing (and limiting!) areas of research in physics. Maybe Smolin was even correct to try to address all such diverse audiences, but it does result in each of the three audiences having to put up with material which is primarily directed at the other two.

      The four parts of the book are really quite different from each other, and Part IV is especially very different from the rest. In this section Smolin concentrates most of his arguments that string theory has improperly become “the only game in town”, that while there is still a lot of hope for string theory (in his view), other competing theories in physics have not been given sufficient attention and funding, that string theorists as a group tend to be somewhat arrogant and cultish in their attitudes and behavior, and so forth. I think it is safe to say that our whole group agreed with him on these and similar sociological points.

      Rich expressed our general feeling when he remarked that “because string theory is not testable by experiment, physics is not going anywhere. I liked [Smolin’s] ideas such as on the importance of the clash of ideas. He proved his point that physics is going down a very shallow path.” Rosie agreed that we should also be investing in investigating alternate theories besides string theory. Kevin also remarked that he definitely agreed with view that “physics is stuck”.

      But John, especially, was not happy with the overall tenor of the discussion, despite this general agreement with Smolin about the sociological issues. John remarked that he felt that “the majority of people in the group missed the point of the book.” He said he liked the first part of the book as well, but also put his emphasis on the sociological problems that Smolin raised. John said he strongly agreed with Smolin’s premise about the great tendency toward “groupthink” in physics. He did criticize some of Smolin’s comments in the “What is Science?” section as being too psychoanalytic, but overall praised the book and said that its major points were well-taken.

      Ron asked, “Why tell me about the sociological problems in the universities and within physics? What can I do about it?” But Rich and some others disagreed with this, and said that they view it as important for everyone in society to at least have some knowledge of these sorts of problems. (Scott sat there thinking silently: “If this society were really a democracy, and valued input from the public about anything, it would definitely be important!”)

      Many of the reviews of this book (including the one in Scientific American) wrongly state or imply that Smolin is a critic of string theory itself. Actually this does not seem to be his view at all. He merely thinks that until the correct theory is figured out, string theory should not be “the only game in town”. Scott thinks that while a multi-faceted approach is correct in science, actually string theory seems to already have been shown to likely be a dead end. And that Smolin should, if anything, be faulted for not being far more critical of it than he is! As far as the “only game in town” claim by the string theory cultists go, physicist John Baez’s comments struck a pleasing note with Scott:

      Another closely related argument [by the string theorists offended my Smolin’s book] was “String theory is the only game in town.” Until some obviously better theory shows up, we should keep working on string theory.

      It’s true there’s no obviously better theory than string theory. Loop quantum gravity, in particular, has problems that are just as serious as string theory.

      But the “only game in town” argument is still flawed.

      Once I drove through Las Vegas, where there really is just one game in town: gambling. I stopped and took a look. I saw the big fancy casinos. I saw the glazed-eyed grannies feeding quarters into slot machines, hoping to strike it rich someday. It was clear: the odds were stacked against me. But, I didn’t respond by saying “Oh well—it’s the only game in town” and starting to play.

      Instead, I left that town.

     It’s no good to work on string theory with a glum attitude like “it’s the only game in town.” There are lots of other wonderful things for theoretical physicists to do. Things where your work has a good chance of matching experiment... or things where you take a huge risk by going out on your own and trying something new.2

      Scott raises another annoyance from Smolin and theoretical physicists in general, namely their use of terms such as “discoveries”, “evidence”, “it turns out that...”, and so forth, when they are only talking about their half-baked theories and making no reference whatsoever to experiments or the real world. True, Smolin notes the weakness of string theory in not making testable predictions, but he seems to be far more concerned with other problems with it (such as the fact that it has not even been formulated as a single coherent theory yet). But “it turns out that” much of the time when Smolin and the others refer to “discoveries” or “evidence” they are really only referring to some theoretical “finding” or “theorem” within their abstract mathematical scriblings. Here are a couple examples: On p. 134 he talks about a conjecture that the five consistent superstring theories were actually just a single theory, and says: “Witten had found a great deal of evidence for the conjecture, based on dualities that had been found not just beween the five theories but between string theories and theories in eleven dimensions.” And on p. 129 Smolen says: “Witten’s proposal was based on a series of recent discoveries that had uncovered new facets of string theory and greatly increased our understanding of it.” Maybe theoretical physicists should be prohibited from talking about “evidence” and “discoveries” since they seem so little concerned with the real thing!

      Scott has a few more comments: He liked the first part of the book where Smolin applied the “unification” interpretation to past advances in physics, going back even to Galileo and Newton. But while this further explicated the “unification idea”, it also raised a question in his mind as to whether the fixation on this single notion in modern physics might itself be a cause of certain difficulties. When applied to things like the “unification of motion and rest” the notion somehow feels forced and like it merely brings out one of many ways of looking at what Galileo and Newton really accomplished.

      Scott thought that the brief run down on the maverick physicists and their non- or anti-string theories (Part III of the book) was one of the highlights. He also appreciated Smolin’s attack on the “anthropic principle” in chapter 11, but thought it should even be stronger and part of a more general criticism of the current trend toward “religious physics”. (Smolin himself begins his Introduction by saying “There may or may not be a God. Or gods. Yet there is something ennobling about our search for the divine.” Scott would rather say there is something debasing and idiotic about it!) And finally, Scott especially appreciates Smolin’s attacks on cultism in physics and science. Unfortunately cultism is also a problem in politics—even in the sort of politics which is attempting to be scientific itself (Marxism). (From what Smolin says (p. 303), even his own grandmother illustrated this sort of pseudo-scientific “Marxism”, and he is unable to see any other possibility for it.) Defeating such cultism and other forms of dogmatism within what is called ‘Marxism’ is an extremely important part of applying what should be the scientific approach even there, says Scott.

— Notes —

1   On pages 56-57 Smolin says: “The gauge principle is best understood in terms of something physicists refer to as a symmetry. Put simply, a symmetry is an operation that doesn’t change how something behaves relative to the outside world. For example, if you rotate a ball, you don’t change it; it’s still a sphere.” Then Smolin talks quite a bit more about symmetry, which all of us understand pretty well. Then he continues: “Knowing the symmetries is a good thing, because they tell you something about the forces involved. ...[in the second example we learn] that certain nuclear forces can’t tell the difference between a proton and a neutron. Sometimes all we get from the symmetry is such partial information about the forces. But there are special situations in which the symmetries completely determine the forces. This turns out to be the case for a class of forces called gauge forces. I won’t bother you with exactly how this works, as we won’t need it. But the fact that all the properties of a force can be determined by knowing the symmetries is one of the most important discoveries of twentieth-century physics. This idea is what is meant by the gauge principle.” Scott, however, says that while this sort of introductory “explanation” might give someone a very vague idea about what a gauge theory is, it is by no means a deep enough understanding to then go on to really appreciate the significance of Maldacena’s “revolutionary idea... that a string theory could have a dual description in terms of a gauge theory.” After a while the continuous construction of new concepts in terms of ones which are still quite vague to the reader leads to actual incomprehensibility even if the words can be read and repeated.

2   John Baez, “This Week’s Finds in Mathematical Physics (Week 246)”, Feb. 25, 2007, at:

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