Physics World on String Theory

Despite my abusive treatment of his article Stringscape here recently, Matthew Chalmers was kind enough to send me a copy of the September issue of Physics World, which contains three shorter pieces about string theory (available on-line only to subscribers).

One of the articles is by Fred Goldhaber and entitled Scientific faith put to the test. It’s a scathing attack on the anthropic string theory landscape program, describing it as “antiscience” (rather than my favorite, “pseudo-science”). Goldhaber characterizes this sort of research as “antiscience of the left”, with its adherents promoting the idea that we can’t ever understand some things since they are due to chance. He contrasts this to the “antiscience of the right”, which promotes the idea that we can’t understand things because they come from supernatural origin, and finds both attitudes equally unscientific. As for where antiscience comes from, he has this to say:

On the left, I think that it stems from arrogance (“If I can’t figure it out, no-one ever will”). On the right, I think it comes from defensiveness (“If science is right, religion must be wrong, and that can’t be”). In the end, antiscience on both side boils down to vanity. While we need to stay alert for the vanity of those advocating antiscience, we also should guard against vanity in the name of science.

He ends on a more optimistic note, writing that he does see a difference in those on the “left”. They remain physicists, and if someone finds a “promising route to picking out the right solution to string theory”, they would leap to pursue it. He doesn’t speculate on what they would do if someone shows that string theory just inherently can’t ever predict anything…

Philosopher of science Steven Weinstein has a piece with the title Philosophy pulls strings, which tries to make the case that string theory is leading to some new interaction between physics and philosophy, since it “forces us to tackle issues that cross both disciplines.” As far as one of his topics goes, the anthropic pseudo-science, the main role I see for philosophers is to forcefully point out to the scientists involved that they are doing something intellectually highly disreputable and should stop. He also discusses a much more non-trivial and interesting topic, that of the philosphical questions about space and time raised by quantum gravity, a subject where philosophers may or may not end up having something quite useful to contribute.

Philosphers Nancy Cartwright and Roman Frigg contribute a very interesting article about how scientific theories are evaluated, entitled String theory under scrutiny [available here, thanks to commenter “R” for pointing this out]. The make the important point that immediate experimental testability of a theory is not all there is to deciding whether something is science or not. When scientific ideas are new, they often are not understood well enough to be able to extract definitive predictions from them. Theorists are generally engaged in research programs, the end result of which is supposed to be something experimentally testable. In order to evaluate a research program, you can’t just note that it isn’t predicting anything, you have to evaluate its prospects for reaching its stated goals. They describe good research programs as “progressive”:

Good research programmes are those that are progressive, i.e. those whose theories get better and better, even if individual theories face serious difficulties at certain times.

The fundamental problem with string theory is that, as far as its central goal of unifying physics goes, over the last nearly 25 years it has not only not made any progress toward explaining anything about particle physics, but, quite the opposite. Everything that has been learned about string theory makes it more and more clear that the original hopes for getting unification this way were just misguided and can’t work. The derivative here is the wrong sign.

There are areas in which string theory has had successes, notably in mathematics and in strongly-coupled gauge theories. But these are really different research programs, and the fact that progress has been made in them doesn’t change the facts about the colossal failure of the unification program. Cartwright and Frigg try and put various other “dimensions” on the string theory research program, including that of “elegance and simplicity”, writing that:

Radical string critics would then conclude that string theory is progressive only in the dimensions of elegance and simplicity (in the sense that the theory only contains one class of basic objects – strings – from which all the basic particles and forces follow), while being largely stagnant in the other dimensions.

As a “radical string critic”, I don’t see things this way. According to M-theory, “string theory” is not a theory of “one class of basic objects”. Strings are just part of a hugely complicated picture, one which at the moment is neither elegant nor simple. String theorists hope that there is some elegant and simple underlying theory, but they have not been able to come up with it despite a huge amount of work. Whatever underlies M-theory, it may be something very complicated. Perhaps M-theory is just a rather obscure corner of a story very different than what string theorists are hoping to find, one that may tell us some interesting things, but just doesn’t have anything to say about how to unify particle physics.

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20 Responses to Physics World on String Theory

  1. M says:

    Now I understand why Lubos hates the anthropic string landscape: it is “antiscience of the left”.

  2. R says:

    The article by Cartwright and Frigg is available here.

  3. Jon says:

    Hi Peter,

    While your views do have merit, I don’t think the current string-theory situation will change any time soon. Supposing string theory *is* found to lack in its substantive goal of unifying physics, what other alternatives do you think has the same degree of appeal… I’m not aware of any. (Certainly LQG and the host of other programs don’t carry the same intellectual appeal and challenge to grad students and postdocs).

    In short, either strings or nothing.

  4. Peter Woit says:

    As for what has the same degree of appeal as a failed idea that has become a pseudo-science (the landscape), well, actually just about anything at all….

    More seriously, I’ve always said that the problem is not that there are good ideas about unification being ignored, but that there aren’t good ideas (at all, string theory now clearly isn’t one). So the question is how to change the reward structure to encourage people to come up with new ideas. I don’t see any evidence that particle theorists of any influence are taking this problem seriously. At the moment the attitude seems to be that the best thing to do is to hide one’s head in the sand and wait for experimental results from the LHC to save us. From what I’ve been hearing lately, people may have to keep their heads in the sand longer than they expected….

  5. Elegant Simpleton says:

    Is Yang-Mills field theory elegant or simple? To see the elegance one needs to have studied for many years, both geometry and physics. To see the simplicity – well I don’t see that it’s all that simple – unless one sees it within the context in which it arose – in which case one needs to know a lot already.

    The criteria of elegance and simplicity are aesthetic judgments made within the context of expertise. To find a particular treatment of Galois theory elegant one has to first know several treatments of Galois theory, understand them, and have thought about the difficulties involved in describing the theory coherently. Not everyone has the preparation to do this. To someone without the preparation, no approach appears either elegant or simple.

    Pauli’s way of handling tensor algebra was neither elegant nor simple, though it worked.

  6. Kasper Olsen says:


    Nancy Cartwright and Roman Frigg are philosophers; they are able to throw names like Kuhn, Lakatos and Popper into the stringscape, but not much else.

    If you tell them, that e.g. the mass shell condition is this and that, they will have no idea what you mean; if you tell them, that the string sigma model is this and that, they will have no idea what you mean; and if you tell them, that the string tension is related to the Regge slope parameter by a certain relation, they also will have no idea of what you mean.

    Elegant Simpleton is correct here in saying, that “The criteria of elegance and simplicity are aesthetic judgments made within the context of expertise” and therefore their views on a string is of little interest. Except for other philosophers, I guess.

  7. dragon says:

    The record of philosophers intervening in physics is mixed. Sometimes it has been worthless; other times it has made more sense than what physicists have said about the same issue. The most extreme example of this that I know is the case of work on the arrow of time. Huw Price

    has made genuine contributions to our understanding of this. Whereas Lubos Motl claims that the arrow arises from the structure of language, from the way we ask questions. That’s right, LM thinks that a postmodernist analysis is the only way to go. In short, if you want real philobullshit, an over-confident physicist is the man to ask. So the views of philosophers on physics should not be dismissed out of hand.

  8. Chris Oakley says:

    So the views of philosophers on physics should not be dismissed out of hand.

    Being less crazy than LM is not really setting the bar very high.

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  10. Thomas Love says:

    I’m not comfortable calling string theory “Antiscience”, it is more specialized, so call it “Antiphysics”. “Certainly Repulsive AntiPhysics”.

  11. tytung says:

    The relation between philosophy and fundamental physics is subtle and complex. Remember, Einstein himself is more philosophical, and less mathematical, than most of his contemporary physicists.
    That the philosophers are not equiped with detailed physics knowledge doesn’t mean that they are unable to give valuable insights into it.
    As I see it, all science is to investigate nature within a set of assumptions, philosophy attempts to step outside and examine them.

  12. I liked the observation that bad science can stem from arrogance. I believe that there is a big gap between what is actually being delivered and what is actually known when you look in the details.

    I’ve tried to put that in a humoristic way, imagining what would happen if MacOS X had been introduced by Brian Greene instead of Steve Jobs. I’m not sure anybody other than me will find it funny 😉 but I thought I’d share anyway.

  13. dragon says:

    “Being less crazy than LM is not really setting the bar very high.”

    But a lot of people respect his views on technical questions in physics [if in no other field]. So he provides an example where someone supposedly competent in physics has been led into serious error, in *physics*, by doing philosophy badly.

  14. Eric says:

    There’s nothing wrong with LM’s knowledge or views on physics. However, he just appears to be very intolerant of those with views which differ from his. In regards to those with crackpot views (and let’s be honest, there are a lot of these types populating the blogs), I can sympathize. However, he can also be extremely rude and insenstive to even those who are not crackpots.

    Of course, in regards to his views on other subjects, LM is clearly a crackpot himself.

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  16. Kris Krogh says:

    The philosopher Grete Hermann correctly identified a fatal error in John von Neumann’s pivotal “proof” of the impossibility of hidden variables in quantum mechanics. While that proof was widely cited, she was totally ignored for twenty years, until John Bell took up her case. She is still little-known, since the history of physics is written by physicists. (Usually ones with a preference for the Copenhagen interpretation of quantum mechanics.)

  17. lisistrata says:

    There’s nothing wrong with LM’s knowledge or views on physics.

    If you’re talking about his published work, I believe you. I’ve not read it, so there’s no reason for me to doubt your words.

    If you’re talking about his views on physics as they appear in his blog, then I strongly disagree with you. Statements like the SU(2) symmetry group of weak interactions can be derived from unitarity, or that the existence of neutrinos can be deduced from the existence of charged leptons, or that experimental results are neither important nor needed, that’s what I would call plain ignorance both of physics and its history…

  18. Kasper Olsen says:


    Grete Hermann was also a mathematician, and this alone made it possible for her to understand the math involved; just being a philosopher would not have been enough to identify this “error” in von Neumann’s argument.

  19. Kris Krogh says:


    Yes, Grete Hermann was also a mathematician. But I think Tytung has a point:

    As I see it, all science is to investigate nature within a set of assumptions, philosophy attempts to step outside and examine them.

    She avoided an assumption of von Neumann’s, which David Mermin describes as “silly.” (Maybe I would use a different adjective.) Why, in twenty years, didn’t physicists notice a silly mistake in a fundamental proof?

    We need more people willing to think outside the box, like Einstein and Bell.

  20. notaphilosopher says:

    Eric said: “There’s nothing wrong with LM’s knowledge or views on physics.”

    I think you are missing dragon’s point. He is referring [I think] to an argument LM had with Anthony Aguirre [a genuine expert] about the origin of the second law of thermodynamics. To everyone’s surprise, LM went all philosophical and claimed that the low entropy at the beginning of time does not need to be explained because when we ask questions, we always ask about the future based on what we know about the past. *Therefore* there is nothing to explain. Here is a concrete example where LM was talking nonsense *about physics* because he got the philosophy wrong. Of course everyone who disagrees is an idiot, is “humiliating Boltzmann” etc etc all the usual crackpottery, but that is just the icing on the cake: the point is that LM became a *physics* crackpot, at least for the time being, because he thinks he can play philosopher. Of course Kasper O might argue that LM might have avoided making a fool of himself by staying away from philosophy altogether and trying to think about a physical basis for the arrow of time…….

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