The String Theory Wars

Posted by jrosenhouse on September 28, 2006
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Have a look at this article from the current New Yorker. It focuses on the recent anti-string theory books from Lee Smolin and Peter Woit. The article provides a decent summary of Smolin’s and Woit’s views, but it is seriously marred by the lack of any contrary views of the matter. The views expressed by Smolin and Woit appear to be in the minority among physicists generally. From reading this article you would have no idea why that is.

For example, the article includes paragraphs like this:

The usual excuse offered for sticking with what increasingly looks like a failed program is that no one has come up with any better ideas for unifying physics. But Smolin and Woit have a different explanation, one that can be summed up in the word “sociology.” Both are worried that academic physics has become dangerously like what the social constructivists have long charged it with being: a community that is no more rational or objective than any other group of humans. String theorists dominate the country’s top physics departments. At the Institute for Advanced Study, the director and nearly all of the particle physicists with permanent positions are string theorists. Eight of the nine MacArthur fellowships awarded to particle physicists over the years have gone to string theorists. Since the fall-off in academic hiring in the nineteen-seventies, the average age of tenured physics professors has reached nearly sixty. Every year, around eighty people receive Ph.D.s in particle physics, but only around ten of them can expect to get permanent jobs in the field. In this hypercompetitive environment, the only hope for a young theoretical physicist is to curry favor by solving a set problem in string theory. “Nowadays,” one established figure in the field has said, “if you’re a hot-shot young string theorist you’ve got it made.”

Both authors also detect a cultlike aspect to the string-theory community, with Witten as the guru. Perhaps, it has been joked, physicists might have an easier time getting funding from the Bush Administration if they represented string theory as a “faith-based initiative.” Smolin deplores what he considers to be the shoddy scientific standards that prevail in the string-theory community, where long-standing but unproved conjectures are assumed to be true because “no sensible person” – that is, no member of the trib – -doubts them. The most hilarious recent symptom of string theory’s lack of rigor is the so-called Bogdanov Affair, in which French twin brothers, Igor and Grichka Bogdanov, managed to publish egregiously nonsensical articles on string theory in five peer-reviewed physics journals. Was it a reverse Sokal hoax? (In 1996, the physicist Alan Sokal fooled the editors of the postmodern journal Social Text into publishing an artful bit of drivel on the “hermeneutics of quantum gravity.”) The Bogdanov brothers have indignantly denied it, but even the Harvard string-theory group was said to be unsure, alternating between laughter at the obviousness of the fraud and hesitant concession that the authors might have been sincere.

Incendiary claims, and ones I’m sure most physicists would reject. But in the article the views of Smolin and Hoit are presented entirely uncritically.

As an outsider looking in, I would want to know how physicists respond to these charges. After all, creationists level precisely the same charges against university biology departments (that they are ruled by dogmatic Darwinists yada yada). And in that context I know the charge is bogus. I suspect the same is true here. Physicists are not receiving professorships at prestigious institutions merely for expressing their support for string theory. They are receiving them because they have made significant contributions to our understanding of important open questions.

Smolin in particular has been receiving a lot of uncritical press attention lately. I wish we would see more in the way of replies from string theory supporters. I know that Brian Greene recently debated Smolin on NPR’s Science Friday. Sadly, the transcript does not seem to be freely available online.

At any rate, the New Yorker article is worth reading despite the lack of balance. It is likely to be old news to people who follow these things closely, but it provides a nice run-down of the issues nevertheless.

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Comments

  1. #1 SLC
    September 28, 2006

    The emphasis on string theory sounds like what used to be called the bandwagon effect. Somebody writes an interesting paper and suddenly everybody clinbs on the bandwagon. Back in the days when I was in the field, we had Regge poles, dispersion theory, bootstrap dynamics, group theory, current algebras, and the Veneziano model, all in the space of 12 years. That’s not to say that these ideas were bad; in fact, some of them were excellent. However, most of the papers published in these areas did not advance the state of knowledge, but certainly increased the size of the journals!

  2. #2 Bob
    September 28, 2006

    There’s a HUGE difference between evolution and string theory. For the former, there’s a mountain of empirical evidence. For the latter, lots of nice theories but…

  3. #3 Rob Knop
    September 28, 2006

    I don’t understand string theory enough to really have an informed opinion. However, I was talking to a colleague of mine, another observational astronomer (albeit an X-ray and gamma-ray guy) at a Physics department, and I asked him his opinion on the matter. My opinion is pretty close to his.

    There are a lot of really smart people out there who *do* think there’s something to String Theory. What’s more, if you think about how science is done, the people who would be *most* famous would be the ones who could poke serious holes in String Theory. If there were relatively low hanging fruit in poking holes in String Theory, you can be sure that some young, not-yet-in-the-bandwagon theorists would grab it, and make quite a name for themselves.

    It maybe that String Theory isn’t The Answer, but I suspect it will take more time before we really know that. Yeah, it hasn’t given us the world yet, and hasn’t even really given us testable predictions yet, but it also hasn’t fallen apart and stagnated either.

    I’m willing to continue having some trust in the string theorists.

  4. #4 Jason Rosenhouse
    September 28, 2006

    Bob-

    I wasn’t trying to compare evolution as a scientific theory vs. string theory as a scientific theory. Rather, I was merely expressing skepticism that the prevalence of string theory in physics departments is the result of tribalism and prejudice, as opposed to its promise as an active field of research.

  5. #5 Michael Hopkins
    September 28, 2006

    I know that Brian Greene recently debated Smolin on NPR’s Science Friday. Sadly, the transcript does not seem to be freely available online.

    It might not be a transcript, but you can certainly listen to it for free. Follow your link and look to the right. I am listening to it right now.

  6. #6 Colst
    September 28, 2006

    Rob –

    (Keeping in mind that I likely have an even less informed opinion than you, my exposure is almost entirely through Brian Green – a talk, a book, and the TV series)

    I’m not sure the poking holes or low-hanging fruit analogies work. Generally, that either consists of mathematical flaws showing that the theory didn’t predict what it was thought to predict or showing that what it predicts is wrong. Without predictions, I don’t know that low-hanging fruit is even possible. I suppose a hole could come in finding a fatal hole in the math that would cause the whole thing to collapse, but that doesn’t need to exist – the math can be perfectly fine and still not describe reality.

    Woit and Smolin, if I understand correctly, are not arguing that string theory is wrong, they’re arguing that it has been elevated to a status it doesn’t deserve at a cost to other lines of inquiry.

    I’m not in any sort of a position to accurately evaluate whether their claims have merit, which is why I, like Jason, would like to hear more from string theorists and something from people close enough to the situation to have an informed opinion. And on that note, since I suspect your opinion is more informed than mine, I’m glad you posted.

  7. #7 PhysioProf
    September 28, 2006

    “I’m not in any sort of a position to accurately evaluate whether their claims have merit, which is why I, like Jason, would like to hear more from string theorists and something from people close enough to the situation to have an informed opinion.”

    I agree completely. I have read both Woit’s and Smolin’s books (Smolin’s was much easier to understand), but I have no ability at all to judge the merits of their claims. I will say that Smolin’s general discussion of the philosophy and sociology of science rang very true to me based on my experiences as a physiologist. If anyone has links to rebuttals by string theorists on blogs or elsewhere, that would be helpful.

  8. #8 Joe
    September 29, 2006

    NPR transcripts are available through your university library, they are in the Lexis-Nexis database.

    Joe

  9. #9 PhysioProf
    September 29, 2006

    Here are some snippets from the debate:

    Smolin (on his motivation for the book): I was very interested in and am very interested in the idea that there’s a close connection between science when it thrives, when it’s doing well, and a democratic society when it’s doing well. And I wanted to use the case of the theory that was not leading up to expectations as a kind of study to try to see how robust science is – and indeed science is robust – and to try to understand better this intuition that is a close connection between science and democratic societies.

    * * *

    Greene (on experimental testing of string theory): And I have to tell you, where we are today in string theory is beyond what I had hoped 20 years ago.
    Certainly we’ve yet to achieve many goals that I still hold dear, that many people in the field hold dear – namely to make predictions, that we can really go out and test and determine whether this theory is right or wrong. So certainly at this moment, skepticism is a healthy attitude towards string theory.

    Smolin (on how bad it is that string theory has not been tested in its 20 year history): history seems to show that when there’s a good idea about unifying different parts of physics, it works fast if it’s going to work….some of the alternative ideas, they’re not – they’re also, as is not string theory, fully developed theories, but they’re ideas, and they do lead to experimental predictions. And those predictions are being tested.

    * * *

    Smolin (on “sociology”): But what I do know and what I care very much about is that there are very good young scientists who are not working on string theory, who are not working, I should say, on the direction that I’ve invested a lot in, which is loop quantum gravity, who have their own ideas and their own directions and those people who are, in a way, kind of orphans.
    But the analogs of the great physicists of the past who always struck out on their own, people like Galileo and Einstein, those people don’t have an easy time because of the way that the university – universities are very adverse to risks. They’re very adverse to hiring people who are working on their own ideas as opposed to ideas that large communities of people have been working on for decades.

    * * *

    Greene (on when string theory might be tested): How long will it take for those experiments to happen? I don’t know. We could get lucky. It could be that the Large Hadron Collider, which will turn on in 2007 or 2008, there’s a chance that we might see some of the fingerprints of string theories through something called super symmetry, certain particles that the theories suggest should be there but nobody has yet seen, through the possibility of seeing the extra dimensions of space that this theory requires by virtue of certain missing energy signatures in the data.
    The possibility that we might confirm string theory through astronomical observations is something that I work on. That’s what I spend my time on these days, trying to see where these strings might leave some imprint in the microwave background radiation, the heat left over from the big bang.
    All of these are long shots.

    * * *

    Greene (on ecouraging non-string-theory approaches): on this other issue of encouraging young students to strike out on their own and pursue their own ideas, I couldn’t agree more. Absolutely.
    I, for instance, in the last couple of years have had students that don’t work on string theory. I’ve had students that have worked on relatively fringe ideas according to the mainstream point of view, something called modified Newtonian dynamics. I’ve had students working on that. I’ve had students working on more bread-and-butter particle physics.

    * * *

    Greene (why people haven’t got bored with string theory because of lack of experimental test): But what’s happened over the course of the last 20 years of development is that the theory has gone through what we call revolutions in our thinking time and time again, which has given a surge of energy, a surge of interest in the theory, which has kept us going even though we’ve yet to make that desired contact with experiment.
    If I just say quickly how we maintain that enthusiasm, I’d say there are really two main reasons. One, the theory is able to embrace all of the major developments in physics having to do with the elementary particles in quantum mechanics that were discovered before string theory in the middle of the 20th Century leading up to the end of the 20th Century.
    They all naturally find a home within string theory. And that’s very compelling to us because usually a revolution doesn’t actually erase the past. It embraces the past but goes further. And that’s what string theory seems to be doing.
    The other side of it is even without the experimental confirmation, string theory has a very intricate mathematical structure that holds together with a kind of tight logical cohesion. There are checks and rechecks in the calculations, enormous number of consistency checks, and they’re all passed. The theory comes through with flying colors every step of the way. And that again keeps us going, keeps us thinking that this theory is at least heading in the right direction.

    Smolin (on Greene’s explanation of the continued appeal of string theory): everything that Brian says is true. And because of that I’m, and many other people have spent time on the theory. There are things that, however, it doesn’t come close to doing [even from a theoretical standpoint]

    [END OF QUOTES]

    It sounds like Smolin and Greene agree completely that there has not yet been any experimental test of string theory. It sounds like Greene is more optimistic that tests will come soon, although even he says it’s a “long shot”.

    In relation to the “sociology” Greene asserts that he encourages his students to explore other areas. Smolin’s point in the book was not that there might not be students who look at other things, but that there are no faculty positions for them later. Greene did not address this.

    Finally, in relation to Smolin’s discussion at the end of the debate of the theoretical shortcomings of string theory–which I didn’t quote explicitly–Greene did not comment.

    As a non-physicist unable to form an independent opinion on the merits, what I took from the debate is that Smolin and Greene actually agree on most of the “facts”, but that Smolin sees the glass as half-empty and Greene sees it as half-full.

  10. #10 Chad Orzel
    September 29, 2006

    I just posted about this on my blog, and here’s a
    Manual TrackBack. If this gets people to recapitulate the string theory wars in your comments, just remember, you asked for it…

  11. #11 Aaron Bergman
    September 29, 2006

    I wrote a rather extensive reply to Woit’s book here.

    I hope people find it interesting.

  12. #12 Aaron Bergman
    September 29, 2006

    In addition to sending people to that 10 page review, let me say a few things here. First, at least on matters of scientific substance, there is no comparison between evolution and string theory. String theory is our best guess for a theory of quantum gravity, and there are a number of theoretical reasons to suspect it might be on the right track. On the other hand, evolution is true and is supported by tons and tons of physical evidence.

    So, getting that out of the way, this statement

    Every year, around eighty people receive Ph.D.s in particle physics, but only around ten of them can expect to get permanent jobs in the field. In this hypercompetitive environment, the only hope for a young theoretical physicist is to curry favor by solving a set problem in string theory.

    is just plain false. Right now, your best in getting a job is to work in cosmology or phenomenology (generally speaking, the branch of particle theory physics dealing with things that might be tested in accelerators). String jobs, while not going away, are getting harder to come by. It is true that a hot-shot young string theorist will probably get a job, but that’s true mostly the the extent that a hot-shot young anything will probably get a job somewhere.

    As for the Bogdanov affair, the description is just plain wrong. The papers have almost nothing to do with string theory and were published in journals that string theorists generally do not publish in. They were also never placed on the online ArXiv ensuring that nobody other than the referees read them (and probably not even the referees, it seems.) I also strongly doubt the statement that the Harvard string theory group was unable to figure out if they were nonsense or not. This statement comes from an anonymous e-mail forwarded by Laurent Friedel and the author has never come forward to explain what he or she meant. I can say that, at the time I was a graduate student, and I was able to tell that they were nonsense, and I can provide Usenet links to back this up. I know who’s at Harvard and it’s unbelievable to me that they would not have been able to see that the papers were crap.

    Finally, there are some interesting things to be said about the current incentive system in theoretical physics, but I find Smolin’s commentary on the subject to be tremendously condescending. Perhaps I should leave it at that.

  13. #13 Andrew Cook
    September 29, 2006

    String theory is the bread and butter of some physics departments, but physicists at other universities are quite skeptical. I’m a graduate student at the University of Oregon working towards a PhD in theoretical optical physics. None of the theorists here think that string theory soundly answers any fundmanetal physics questions, but most find it interesting. Professors here seem to agree that a lot of cool things are happening in string theory, but that it properly belongs in the field of mathematics. At UO there are people working on string theory in the math deparment, and they frequently give talks in our theory seminars. Mathematicians seem to be excited about string theory because it has really expanded the field of topology, and it has given mathematcians a lot of new things to prove. But, there is a difference between physics and math. Physics is an experimental science. You can postulate plenty of distinct universes that in some limit resemble this one, but if you can’t predict anything new, why should we assume that a particular higher dimensional model is right? Also, string theory isn’t falsifiable. With 10+ dimensions to work with, you have a tremendous freedom to fit parameters to new experimental results. However, pretty much all physicists think that we’ll someday unify gravity with the other forces. So when a string theorist asserts that we should fund string theory research because it’s the best attempt at unification that we have, it’s a persuasive argument. I personally think that string theory falls far short of a compelling model, but unification is important, and you have to put the money somewhere. I’m skeptical about string theory because a hallmark of a really great model is that it gains tremendous consensus among scientists in the field. If string theorists suddenly start agreeing with each other with regard to which variant of string theory is right, I’ll certainly it more seriously.

    Andrew

  14. #14 Jason Rosenhouse
    September 29, 2006

    Aaron-

    Thank you for the link to your review. I found it very helpful, and it’s precisely the sort of counterpoint I would have liked to see in the New Yorker article.

  15. #15 jianying
    September 29, 2006

    I find all this quite ironic, smolin has some quite untested, and possibly untestable idea of his own, moreover his theoretical work has many parallels to string theory. In fact, what probably revolutionize physics on the scale of newton or einstein, is if some future theorist demostrate that there exist a duality between Loop Quantum Gravity (smolin’s work) and string theory.

    I suspect the animosity between the two camps has a subtle but definite effect of slowing reseach in this direction from happening.

  16. #16 JohnPhys
    September 30, 2006

    I think Smolin makes a convincing argument, but I think most people are misinterpreting the argument he’s making. He’s not saying to abandon all effort on String Theory. Rather, he seems worried that the huge amount of resources (manpower, brainpower, funding) that are dedicated to something that has given no experimental predictions in 20 years is a large waste. On the surface (not having read the papers on string theory and such), I would have to agree. I would much rather see a lot of varied avenues of research in to fundamental issues rather than having most of the discipline put all it’s effort in to one particular theory.

    One thing to also keep in mind with Brian Greene’s comments is whether or not string theory is unique in predicting supersymmetry, extra dimensions, etc. I don’t believe it is, but I am no expert.

  17. #17 Aaron Bergman
    September 30, 2006

    I would much rather see a lot of varied avenues of research in to fundamental issues rather than having most of the discipline put all it’s effort in to one particular theory.

    This is one of those things that sounds very nice and is easy to talk about in theory, but turns out to be very difficult to implement in the real world where people want to get a job.

    It’s not that people only willing to hire string theorists, however; it’s that most people think the other ideas just aren’t very good. People vote with their feet. Or pencils, perhaps.

  18. #18 Rob
    November 20, 2006

    I must admit to not know a whole lot about strings (my topic is radio waves and the ionosphere) but the way I have heard these theories described is that the theory is quite sound but there is so little data that virtually none of the parameters are fixed (you can have 26 or 13 or 17 dimensions for example – sorry these are meant to be indicative not actualy possiblities) and that you can make any “reality” just by changing some of the parameters