String Theory Makes Prediction – Pig Grows Wings

Several people have pointed out to me the latest press release hyping the supposed testability of an extremely speculative theoretical idea, which then gets promoted to a “scientists finally find way to test string theory” story, and spread throughout the popular press.

This week’s hype example comes from Duke University and is entitled Scientists Predict How to Detect a Fourth Dimension of Space. It deals with a recent paper by Keeton and Petters, one in an interesting series of papers about using gravitational lensing to test GR. This latest paper deals with possible lensing effects of primordial black holes in braneworld models. The hype isn’t really in the paper itself, but in the press release, where Petters says “If braneworld black holes form even 1 percent of the dark matter in our part of the galaxy — a cautious assumption — there should be several thousand braneworld black holes in our solar system.” Braneworld scenarios can have any energy scale one wants, and the only thing one knows about this is that it can’t be below a TeV or so, because otherwise we’d have some evidence from accelerators for these scenarios, and we don’t have a shred of such evidence. I just don’t see any justification for calling the idea that 1% of dark matter is made up of these black holes a “cautious assumption” about what a braneworld scenario would “predict”, or for claiming that they have a testable “prediction” for what the GLAST satellite will see, in any conventional scientific use of the word “prediction”.

As usual, the hype level increases as the story is reworked into popular science stories elsewhere. For instance, at Ars Technica it is the inspiration for an article called String theory makes prediction – pig grows wings. The writer begins by giving a completely incorrect explanation of why string theory has made no experimentally verifiable predictions to date:

because the governing equations which work so well at very small scales (and very high energies) become impossible to solve when applied at lower energy or larger scales. Thus theorists must make approximations, which then have another layer of approximation applied before any measurable numbers fall out. At this point everything falls apart because that second layer of approximation is governed by existing experimental results, which means that no new predictions are made.

this repeats the usual misleading claim of string theorists that they have “equations which work so well at very small scales”, and the only problem is that it is hard to extract physics at long distance scales from these equations. I have no idea what this “second layer of approximation” is, best guess is that it is the “approximation” of assuming that string theory gives you the standard model at low energies, an “approximation” that does kind of make it hard to extract predictions that disagree with the standard model.

The writer also refers to another bogus “prediction of string theory” he attributes to Ulf Danielsson, and concludes that “now we have some real testable predictions from a theory of gravity derived (not in the mathematical sense) from string theory.” The parenthetical remark at least gives some indication that something very fishy is going on, and he does end the piece by pointing out that:

A word of caution should be attached at this point. Braneworld gravity is one of a number of string theory derived candidates, so if braneworld fails don’t expect it to take string theory down with it.

This particular piece of hype so far has been uncritically repeated at various places, including here and here, from there making it onto endless blogs, such as here, here, here, and here.

Update: As usual, picked up by New Scientist.

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13 Responses to String Theory Makes Prediction – Pig Grows Wings

  1. Who says:

    maybe this is simply a question of terminology. A pig with feathers is a turkey, and if it sits up in a tree it’s called a superturkey.

  2. Knotted String says:

    The squadrons of flying pigs (turkeys) that string theorists are so good at breeding will hopefully deposit some manure on the Landscape, and allow the growth of new ideas!

  3. Dan says:

    Dear Peter,

    as a particle physicist, do you think John Baez, Lee Smolin, Markapolou’s approach to standard model physics through LQG through “loop braids” is promising?

  4. Who says:

    Dan, I realize you asked a specific question of Peter (and not of the gallery) but would like to respond.
    I am glad to see you making an effort to promote real discussion—I regret my flippant comment earlier about the pig with feathers because it seems to have precluded seriousness.

    Since Peter’s post is about TESTABILITY, and you mention Smolin’s stuff (which may be very different from Baez’—I am not sure about the connection yet) I will mention a case of quick falsifiability that Smolin mentioned on page 18 of his recent hep-th/0605052

    …The discovery that these theories generically predict emergent particle states certainly leaves them vulnerable to quick falsification. While there is preliminary evidence that a large class of theories can reproduce some features of the standard model, there is a lot that these theories have to get right so as not to disagree with observation…

    What he was talking about in that passage is, I think, what you were referring to. So there is a testability angle to it although it is a different pig. (maybe not a pig, either, but a kind of unicorn, or platypus)

  5. woit says:


    Sorry, but that work is for now in the category of intriguing things I just don’t have time to seriously study, so I can’t intelligently comment on it.

  6. Concerning the “crisis of predictability” of string theory, Lee Smolin will be giving a talk in Paris, sorry if it is off-topic.

    Mercredi 14 juin à 14h30

    Lee Smolin (Perimeter Institute, Canada)

    “Against Symmetry”

    From the Leibniz-Newton debates to the present debates between string theorists and loop quantum gravity theorists two notions of fundamental physics have stood opposed. On the one hand is the Newtonian vision, which is based on a belief in a fixed absolute space and time and which holds symmetry to be fundamental and its breaking to be contingent. Leibniz’s conception of space and time is instead of an ever evolving network of relationships in which complexity is fundamental and symmetry is unnatural and accidental. This distinction characterizes the divide between background dependent theories like string theory and relational, background independent theories such as loop quantum gravity.

    In this talk I analyze the present status of the two traditions and the plausibility of their contemporary incarnations. I show that the crisis of predictability facing string theory is a direct consequence of a conception of unification that is opposed to the principles that underlie the successful modern unifications such as general relativity and gauge theories. I close by describing a new kind of unification which emerges from background independent theories.

    Amphithéâtre A, entrée par le 25 rue de la Montagne Sainte-Geneviève, Paris 5ème

  7. Bert Schroer says:

    Very interesting Christine,
    in QFT such “monade presentations” already exist. An early account of how to build up the reality of QFT (up to 4-dim) in this Leibniz monade spirit, including the spacetime symmetries, the net structure (localization) and (by doing the DHR analysis) the entire inner symmetry structure, can be found in H. W. Wiesbrock and R. Kaehler, Modular theory and the reconstruction of 4-dim. QFT, JMP 42, (2001) 74 and previous literature (this was the last paper this incredible original talent W wrote, after he had developed most of the necessary modular inclusion and modular intersection concepts, and shortly before he had to leave academia because in a world of string hegemony there is no place for this kind of people, he did not even bother to post this paper onto the server).
    I have used part of such a monade picture for a number of years (it pervades all of my recent articles and let me to a formula for localization entropy in
    which is consistent with the new local covariance principle in AQFT).
    The problem to reconstruct the generic curved space-time structure together with quantum matter on it is much more complex. I have tried to build up the diffeomorphisms of the circle from the relative position of monades (i.e. without using the existence of an energy-momentum tensor, but the results are still very incomplete, viz.
    hep-th/0504206 published in AOP) associated to it.
    It seems to me that a program as that of Lee Smolin is very ambitious; maybe one should more modestly understand the relation of quantum physics and monade positioning first in QFT in CST.
    I should add that this relative positioning picture was also on the minds of Brunetti and Fredenhagen when they formulated the new quantum local covariance principle, and last not least, without it Einstein would not have succeeded in his struggle with the fantasmas against covariance he himself created with his “hole argument.”

  8. Dear Bert Schroer,

    Thank you. I am ignorant on monades and several other issues. I am stubbornly following with great interest your contributions to this blog, but I must say a lot of material here is a little over my head. However, it is admirable to learn that are still people in this world interested in discussing physics seriously. I am tired of so much degradation elsewhere.

    Best wishes,

  9. Concerning the question of the multiverse, it is a relief to see a paper on this by serious enough people:

    How Many Universes Do There Need To Be?


  10. Bert Schroer says:

    Dear Christine,
    I am sure that my thinking about string theory did not escape your attention.
    Unless you are an active participant with the “string feel” (i.e. you are with it), it is difficult to understand this phenomenon because it is not scientific, it is rather a sociological phenomenon which takes place where one least expects it, namely in the center of particle physics.
    That irrational things suddenly spread in the midst of rationality is a postmodern phenomenon whose study is the heart piece of the Frankfurt school of philosophy/sociology. Horkheimer, Adorno and Habermas of course were thinking of right arm-raising crowds shouting Sieg Heil in the midst of a culturally and civilisatorically most developed country and about the catastrophic barbaric consequences.
    I must confess that in total lack of any scientific explanation, I also think about this strange grip of mass hype and medial manipulation emanating from the first globalized attempt to get a hegemonial grip on science by manufacturing and not logically deriving scientific facts (fortunately only with a loss of knowledge and not human lifes) in such sociological terms. I really do think about those collective excitations at the time of my birth which I sometimes see in old films and which leave me stunned and bewildered when I look at the new scientific hype. But perhaps it is better to stop with these analogies. otherwise somebody might tomorrow claim that I compared Joseph Polchinski to Adolph Hitler and Aaron Bergman to his stormtrooper, and I may loose my pension in Germany. I have a Brechtian (the identity of the first names is purely coincidental) personality which does not ask for self-sacrifices but only to subterfuge hollow and oppressive systems.
    Let me add that I am totally against racism and political correctness, this is part of the reason I prefer to live in Brazil (by the way I think that such a catastrophy as in Nazi Germany could never have happen in Brazil, even the ethnic cleansing of the Paraguaian indigenous population by your Duke de Caxias is quite a distance away from what happened at the time of the 2. worldwar).
    I would suggest to those physicists who’s future is unsure (and to those string theorist who already foster doubts in their heart) to take in addition some courses in the philosophy/history/sociology of science, because if things within the next couple of years develop the way as with Bush’s Iraq war (also based on maniufactured facts), there will be a lot of interest in the public to understand what happened in the midst of physics and why those things which Michio Kaku, Lenny Susskind and Brian Green were writing about (and telling the US congress) (and all the other popular string theory writers which still appear on the scene) and promised them evaporated in hot air and left such a big crater in the midst of science. This phenomenon will need very thoughtful profound analysis (it is the Zeitgeist which allowed these individuals to do something like this), maybe even a kind of new Frankfurt school geared towards science.
    Actually I am already corresponding with such a Jekill&Hide character who comes from the midst of string theory and who got extremely exited about my polemic article. Since he has all the insider knowledge and an amazing overview about the immense string literature, he can immediatetly back up his analysis by explicit citations and this is much deeper (and not polemic) to what outsiders as Hedrich or myself (the polemic part) can do.

  11. Chris Oakley says:

    String Theorists have not yet been defeated (not politically, anyway), and it is not they, but their critics like yourself who are fleeing to South America.

    So much for the Nazi analogy.

    But they definitely have the “Weltmacht oder Tod” mentality.

  12. Bert Schroer says:

    Chris, things were not quite as bad in Europe, at least at the time when I went to Brazil some years ago. However recently they seem to have taken a turn for the worse, at least in Germany. It is through this weblog that I got to know that one of that new breed of string-possessed referees (a person who knows what particle physics is about and still kept his senses would never do anything like this) deciding the scientific merits of a research project (probably to be funded by the DFG) has thrown out the extremely successful AQFT part and kept the string component (whose contribution has been smaller than any preassigned epsilon, without any hope for future improvements). People like Robert Wald and those who have collaborated with him will immediately understand the devastating significance of this act.
    Chris, it is not Weltmacht oder Tod, it is hegemony and death, but death for the others.

  13. Trevor Turton says:

    It’s fascinating to see such strong divergence amongst physicists on whether string theory is science, maths, or a fashion statement.

    “String theory is the new black”

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