Dispute Chez Les Physiciens

Yesterday evening there was a public debate about string theory held in Paris, between Lee Smolin and Thibault Damour. So far, accounts of the debate have appeared in Le Monde and at Fabien Besnard’s blog Mathephysique.

The Le Monde article is not very informative, but indicates that Damour defended string theory against charges that it was not testable by claiming that it predicted “possible classes of experimentally testable phenomena” at the LHC. Besnard gives a more detailed account, describing how Damour answered these charges of lack of testability with: “Lee, a subtle thinker, surely doesn’t believe himself the naive Popperian position he is defending”. He also evidently claimed that string theory was testable because it would be confirmed if a violation of the equivalence principle was found (he really should talk to Lubos, see here). Remarkably, he also claimed that observation of the kind of DSR dispersion relations that Smolin thinks LQG leads to would not be a problem for string theory, since one could also get them out of string theory (here I think he needs to talk to both Lubos and Jacques Distler).

Update: I hear that the event was recorded, and audio should be available by the end of the week at the web-site linked to above.

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60 Responses to Dispute Chez Les Physiciens

  1. vicar says:

    Aaron said: “A common pastime at lunches in various string groups is to try to figure out why the papers of the day are wrong without reading more than the abstract :). This is a good thing.”

    Oh yes, that’s a really good thing.
    In reality, this sort of attitude is exactly what Smolin means by groupthink. You look at the abstracts and if they do not agree with your preconceptions you have a good laugh and move on to the next victim. The only papers you actually look at are those by names you recognise as being a member of the gang. I have heard some unbelievably naive things being said on the basis of this “let’s just glance at the abstract and decide that the paper is wrong” procedure. This is essentially LM’s approach, and it has led him to write some things that gave me a very bad case of vicarious embarrassment. As for example what he has said about equivalence principle violation over the years, things that would not be tolerated in an undergraduate in any respectable university.

  2. Aaron Bergman says:

    Here it was that I thought groupthink meant mindlessly agreeing with the status quo and not questioning things said within the group. Now, apparently disagreeing with papers counts as groupthink, too. I’m so confused.

    (I hasten to add that the subject of such lunchtime conversations is most often string papers, but now, of course, string theorists will be accused of only looking at string papers and nothing else. Groupthink! And so it goes on….)

  3. mclaren says:

    Eric Mayes remarked:
    There are many compelling reasons for introducing strings and it is far from being ‘baseless conjecture’.

    Compelling mathematical reasons. Not compelling experimental evidence. If I’m wrong, please provide the title, volume number, issue number and page numbers of the peer-reviewed HEP journal that has published experimental results confirming the predictions of string theory that would compel us to believe that string theory is the next necessary step in HEP.

    This really sad thing about this debate is that there are so many ignorant people out there who are easily manipulated by these fallacious arguments.

    Show me the evidence. That’s all that counts. Show me the HEP experiments providing evidence for string theory. Everything else is irrelevant. The two biggest pieces of experimental evidence in HEP in th last 20 years, dark energy and oscillating neutrinos, weren’t predicted by string theory.

    If we’re honest, you have to admit that what is being peddled is us-against-them -ism.

    People are asking for hard experimental evidence. You can’t have experimental evidence for or against a scientific theory if the theory doesn’t even make testable predictions. Without testable predictions or experimental evidence pro or con, the “theory” is not even wrong.

    In this picture, string theorist [sic] are elitists who live in their Ivy League ivory towers telling the common-folk who really no [sic] better what to believe, while the populist heroes Woit and Smolin are the defenders of rationally [sic] and common sense. The truth is that the serious people who are really doing physics will continue to study string theory because it offers the best chance to make progress, by far.

    At some point, you have to recognize that a theory isn’t making predictions and no one knows how to squeeze or tease it into making testable predictions. At that stage, the whole project has become what Hubert Dreyfus calls a degenerating research program. From the nonsensical philosophical arguments now being offered in favor of string theory and judging by its persistant inability to make testable falsifiable prediction, string conjecture seems to be a degenerating research program.

    Eric Mayes’ claim here is the same as Sean Carroll’s faulty argument — string conjecture is valid science because physicists are still working away at it. That’s faulty because it doesn’t matter how many people work at an area of investigation if it produces no tangible results. Thousands of physicists worked worldwide investigating the ether in the 1920s but no results came from that line of investigation. It was a degenerating research program. Physicists eventually abandoned it.

    It doesn’t matter how many people investigate string theory if it continues to fail to produce testable falsifiable predictions. If you’re not making predictions that can eventually be tested in a laboratory, you’re not doing science. It’s just that simple.

  4. Peter,

    You said “My objection is to what I take to be Damour’s claim that an observation of a violation of the equivalence principle would be evidence for string theory. If you believe Lubos, string theory predicts no violation of the equivalence principle, if you believe Damour, it predicts a violation. “

    Doesn’t a dilaton violate the equivalence principle? I thought it had to be massive to confine the violation to short distances.

  5. Aaron,

    Your assertion that theoretical physicists should keep their disagreements private is pretty darn medieval. It’s not in keeping with the history of physics or science generally, and it’s dishonest to hide such disagreements from the people paying the bills.

  6. Aaron Bergman says:

    My god, does nobody read what I say? Or am I really that unclear?

    Let me quote it again: The other point people seem to have missed is the difference between criticizing one colleagues and criticizing their work.

  7. Bee says:

    The other point people seem to have missed is the difference between criticizing one colleagues and criticizing their work.

    hum… I wonder how the ‘sociological’ part of the book had been discussed had it not been written by a physicist but by someone working in, say, the sociology of sciences? I suspect, then the criticism would be it was not written by a ‘colleague’ who knows the field?

    Hi Vicar,

    In reality, this sort of attitude is exactly what Smolin means by groupthink. You look at the abstracts and if they do not agree with your preconceptions you have a good laugh and move on to the next victim.

    nah, you’re mixing up cognitive biases, what you’re talking about is called confirmation bias:

    `a tendency to search for or interpret new information in a way that confirms one’s preconceptions and avoid information and interpretations which contradict prior beliefs. It is a type of cognitive bias and represents an error of inductive inference, or as a form of selection bias toward confirmation of the hypothesis under study or disconfirmation of an alternative hypothesis.’

    and is btw also exactly what Polchinski criticizes about Lee’s book Regarding group-think: you interpret the reaction of string theorists to your book as more evidence for your point of view.

    Entertaining, eh? We can probably spend the rest of our days accusing each other of faulty thinky, or other logical and formal fallacies. I esp. like the Texas sharpshooter fallacy, anybody wants to write a book about it?

    Sorry, Peter, couldn’t resist – this comment section has just gotten too silly.


  8. Peter Woit says:

    Some of the most common automated spam robots operate by posting comments consisting of a generic phrase of indeterminate reference, or a snippet from a previous comment, followed by such a phrase. I’ll just point out that the comments from some people here recently are indistinguishable from those of the spam robots (just that they don’t have a link to a web-site trying to sell something in the “web-site” field).

  9. Peter Woit says:


    In general, massless moduli fields can give violations of the equivalence principle. That’s why some string theorists say “string theory predicts violations of the equivalence principle”. But we don’t see such long-range forces, so string theorists argue that the fields must be massive and short range, and concentrate recently on models where this is true. Some like Lubos, then start going on about how “string theory predicts no violations of the equivalence principle.” The whole thing is kind of ridiculous.

  10. Pingback: Woit vs. Lubos, where’s a punk physicist when you need one « Bob Dudesky

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