Dangling Particles

Lisa Randall has an Op-Ed piece in today’s New York Times entitled Dangling Particles. The title seems to have little to do with the piece, but I suppose it is a play on words on “dangling participle”, a term for a sort of faulty grammar. Randall’s topic is the difficulty of communicating scientific topics, and her comments on the problems caused by scientist’s different use of words and by the complex nature of much science are true enough and unobjectionable.

But I still find the sight of a string theorist lecturing the public on how to properly understand science to be a bit jarring. Randall tries to claim that the difference between the colloquial usage of the word “theory” and the way it is used by scientists is a source of problems with the public understanding of science. She writes

For physicists, theories entail a definite physical framework embodied in a set of fundamental assumptions about the world that lead to a specific set of equations and predictions – ones that are borne out by successful predictions.

Yet she keeps on referring to “string theory”, although the subject is distinctly lacking in specific equations and predictions (she does note that “theories aren’t necessarily shown to be correct or complete immediately”, but the problem with string “theory” is not that we don’t know whether it is correct or complete, but that it isn’t really a theory, rather a hope that one exists).

Instead of devoting their time to writing for the public about the scientific status of issues that they’re not really experts in (e.g. global warming), it seems to me that string theorists would do better to first address the outbreak of pseudo-science now taking place in their own subject. When the intelligent design people get around to noticing how much of the highest level of research in one of the traditionally most prestigious sciences is now being conducted without any concern for falsifiability or traditional norms of what is science and what isn’t, the fallout is not going to be pretty.

Update: Sean Carroll has a posting about the Randall Op-Ed piece over at Cosmic Variance. He quotes approvingly Randall’s claim that Intelligent Designers don’t make a distinction between the colloquial usage of “theory”, meaning an idea not necessarily better grounded than a hunch, and the way real scientists use the term. As for whether string theory deserves to be called a “theory”, here’s a quote from Gerard ‘t Hooft (from his book In Search of the Ultimate Building Blocks):

Actually, I would not even be prepared to call string theory a “theory� rather a “model� or not even that: just a hunch. After all, a theory should come together with instructions on how to deal with it to identify the things one wishes to describe, in our case the elementary particles, and one should, at least in principle, be able to formulate the rules for calculating the properties of these particles, and how to make new predictions for them. Imagine that I give you a chair, while explaining that the legs are still missing, and that the seat, back and armrest will perhaps be delivered soon; whatever I did give you, can I still call it a chair?

Update: Lubos Motl has some comments about Randall’s Op-Ed piece and about my posting. As usual, I come in for a fair amount of abuse, but at least this time I’m in good company (‘t Hooft’s views are characterized as “just silly”).

Update:John Baez points out that the article is now up at the Edge web-site. Over at Pharyngula, there’s a posting about Danged physicists. Evidently biologists are not amused at all about Randall’s comments about evolutionary biology. They seem to think that string theorists are arrogant and prone to going on about things they don’t really understand.

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22 Responses to Dangling Particles

  1. Nigel says:

    Peter, she does comment on this issue in chapter 4 (‘approaches to theoretical physics’) of her book ‘Warped Passages’ although you didn’t focus on that in your review of the book. Lisa there says candidly: ‘The choice could also be phrased as “Old Einstein vs. Young Einstein”.’ She then launches into a discussion of string theory, saying that it seems the only way to consistently unify quantum mechanics and general relativity.

    The two issues with string theory, that there is no hope for tests it because the energies required are 16 orders of magnitude too high, and that there are no end of differing versions of string theory (different brane models, different explanations for the different strengths of gravity and the other fundamental forces). Thus string theory with its 10/11 dimensions and fanciful claims is a bit like Alice in Wonderland, as Lisa admits (it was her inspiration).

    Witten is the man who seems to be responsible for the current mess, and it would be nice to see him defend his arm-waving propaganda claim that string theory ‘predicts gravity’.

  2. logopetria says:

    Of course, there’s another distinct technical use of the word “theory”, namely in mathematics, where X theory can just mean ‘the general field of study that addresses X’. For example, graph theory is the study of graphs, not a particular theorem about graphs. Maybe this is a better way of understanding the name ‘string theory’ – it’s just the whole mathematical field of study of strings, and what they’d be like if they existed. (Although I’m not suggesting this is how string theorists think about it themselves).

  3. Nigel says:

    This ‘string theory’ issue was the problem 100 years ago with ‘ether theory’. There was no single ether theory, there were multiple versions, all contradictory ad hoc models, and not one predicted quantum theory or radioactivity. This was why ‘it’ was really abandoned. You had to have faith to believe in all the ad hoc models, because they were impossible to experimentally prove (as per Michelson-Morley test), just as string theory can’t be proved today. The genius of relativity was bucking the mainstream of his day, by making testable predictions.

  4. Scott says:

    And string theory is not about strings that you tie around your finger that are made up of atoms; strings are the basic fundamental objects out of which everything is made.

    and she was saying something about better communication?

  5. dan says:

    Would you consider the dectection of SUSY-particles or extra dimensions at LHC a successful prediction of string theory? what about deviations from GR some forms of string theory predict?

  6. woit says:

    No, the things you mention may be consistent with string theory but aren’t predictions of string theory. String theory doesn’t tell us what the properties of superpartners will be, how many extra dimensions of observable size there are, what the deviations from GR are, etc. etc. It makes no real predictions: zero, zip, nada.

  7. jobhunter says:

    Given how it is easier today to get a professorship at a major American university as a string-theorist than as a non-string theorist (witness Sean Carroll’s recent public praise for string theory just before entering the job market), I do believe that a genuine legal case could be made that this constitutes discrimination on the basis of religion.

  8. woit says:

    Hi Jobhunter,

    That’s very funny. String theorists will whine that they don’t get all the jobs, phenomenologists and cosmologists get some too. The one religious belief that now makes you truly unemployable in physics departments in the US is Einstein’s belief in the existence of a deep mathematical and geometrical structure to physical reality.

  9. Arun says:

    Motl is now using the Dawkins argument, namely

    Richard Dawkins wrote:

    “Instead of examining the evidence for and against rival theories, I shall adopt a more armchair approach. My argument will be that Darwinism is the only known theory that is in principle capable of explaining certain aspects of life. If I am right it means that, even if there were no actual evidence in favour of the Darwinian theory (there is, of course) we should still be justified in preferring it over all rival theories�.

  10. anon says:

    A confusing writer criticizing confusing writing? I find myself re-reading Lisa’s convoluted sentences and saying, heck, she could have expressed the very same thought with a much simpler, clearer sentence. Also, I find that adjacent sentences in her article are often curiously disconnected. I’d say she has a problem with dangling sentences and dangling thoughts. The title of the piece is emblematic of this problem: it’s left dangling and unexplained.

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  12. absolutely says:

    Perhaps string theory is more of a “system of theory” than a single theory. By that I mean a generator of theories for specific domains.

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  14. Thomas Larsson says:

    Dan,

    Would you consider the non-dectection of SUSY-particles or extra dimensions at LHC as an indication that string theory is wrong? Remember that for almost 20 years, Ed Witten kept stating that string theory makes one prediction, supersymmetry (and one postdiction, gravity). For some reason, he seems to have stopped making these statements now that the LHC draws near…

    Personally, I would consider the discovery of sparticles a strong hint that string theory may be on the right track. However, I would like hard evidence; a sign-bug in the Schoonship program is not good enough for me.

  15. Chris Oakley says:

    IMHO the New York Times and Lubos are going to be the main agents for bringing about the end of Superstrings. The former runs articles on Superstrings with alarming regularity, but in each case it will be evident to anyone who can be bothered to read it (i) that there has not been any significant progress since the previous article and (ii) that after more than 20 years the subject still has not made contact with reality. Lubos’s contribution to the demise of Superstrings will just be that if the most vocal advocate of their subject is a petulant, raving brat, and if they continue to make no more than token efforts to rein him in, then something has got to be fundamentally wrong.

  16. dan says:

    re: thomas larrsson,

    I personally would think the non-detection would rule out certain forms of string theory, those with a relatively low SUSY-breaking value, just as the non-detection of proton decay in SuperKakomoke rules out certain forms of GUT such as SU5.

    almost everyone agrees that the non-detection though would not be fatal to all string theories, just as the absence of proton decay has not ruled out all GUT’s.

    personally such non-detection, though I hope will stimulate research in other QG programs, esp CDT.

  17. dan says:

    re: The one religious belief that now makes you truly unemployable in physics departments in the US is Einstein’s belief in the existence of a deep mathematical and geometrical structure to physical reality.
    ______________________________________________

    Peter,

    Witten and Lubos and Randall would describe string M theory as a vindiction of Einstein’s belief in the existence of a deep mathematical and geometrical structure to physical reality. the top universities all employ string theoriests, although personally, i wish they would employ quantum gravity theorists as an independent category to string theoriests.

  18. Tony Smith says:

    dan said:
    “… Witten and Lubos and Randall would describe string M theory as a vindiction of Einstein’s belief in the existence of a deep mathematical and geometrical structure to physical reality. …”.

    Would Witten and Lubos and Randall have the gall to “describe string M theory as a vindication of Einstein’s belief” that a really good physics model should meet the criterion of being:
    “… a theorem which at present can not be based upon anything more than upon a faith in the simplicity, i.e., intelligibility, of nature: there are no arbitrary constants … that is to say, nature is so constituted that it is possible logically to lay down such strongly determined laws that within these laws only rationally completely determined constants occur (not constants, therefore, whose numerical value could be changed without destroying the theory). …”.

    See Wilczek’s article in the winter 2002 issue of daedalus.

    Tony Smith
    http://www.valdostamuseum.org/hamsmith/

  19. D R Lunsford says:

    Chris O, amen!

    -drl

  20. John Baez says:

    Lisa Randall’s article “Dangling Particles” has appeared on The Edge, a chat forum for the self-proclaimed “digerati”:

    Lisa Randall – The Edge

    So, there will probably be some discussion of this article there soon.

  21. D R Lunsford says:

    Bravo! It is correctly pointed out that Randall (and other STers) behave exactly like the IDers, and their schoolmen forebears, in forcing the argument into a pattern designed to produce the predetermined conclusion.

    Nice find Peter!

    -drl

  22. John Baez says:

    Apparently Brockman doesn’t expect discussion of Lisa Randall’s piece on his Edge website. He just included her essay there because the New York Times version left out parts, which somehow contributed to evolutionary biologists becoming incensed at it. I haven’t compared the versions, so I don’t know what this is all about.

    Here are a few remarks I was going to contribute to that discussion, had it taken place:

    …………………………………………………..

    Lisa Randall mentions how different uses of the word “theory” provide a field day for advocates of “intelligent design”.

    True – but it’s not only here that the definition of “theory” has gotten pulled into the rhetorical struggle over a scientific issue. The same thing happens with the phrase “string theory”.

    Here’s what James Watson of DNA fame says in an essay introducing the book “Darwin: The Indelible Stamp”:

    Let us not beat around the bush – the common assumption that evolution through natural selection is a “theory” in the same way as string theory is wrong. Evolution is a law (with several components) that is as well substantiated as any other natural law, whether the law of gravity, the laws of motion or Avogadro’s law. Evolution is a fact, disputed only by those who choose to ignore the evidence, put their common sense on hold and believe instead that unchanging knowledge and wisdom can be reached only by revelation.

    Compare what the physicist Gerard ‘t Hooft says in his book “In Search of the Ultimate Building Blocks”:

    Actually, I would not even be prepared to call string theory a “theory” – rather a model or not even that: just a hunch. After all, a theory should come together with instructions on how to deal with it to identify the things one wishes to describe, in our case the elementary particles, and one should, at least in principle, be able to formulate the rules for calculating the properties of these particles, and how to make new predictions for them. Imagine that I give you a chair, while explaining that the legs are still missing, and that the seat, back and armrest will perhaps be delivered soon; whatever I did give you, can I still call it a chair?

    The point here is that string theory does not yet make any specific predictions about what we might see in experiments.

    So, “theory” lies on a rhetorical continuum that ranges from “not even a theory” to “not just a theory” – and even real scientists fight about where a given “theory” lies on this continuum.

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