Follow-Ups to two recent postings:

Michael Duff has written a letter to New Scientist complaining about their recent editorial Physics’ greatest endeavour is grinding to a halt. Duff begins by claiming:

History has shown that rapid confirmation by experiment is a poor guide to the eventual value of a physical theory

but backs this up in a rather bizarre way. You might think he would list some physical theories whose experimental confirmation took awhile, instead he lists various theoretical ideas that have been around for a long time, still haven’t been experimentally confirmed, although lots of people are still working on them. Evidently for Duff the value of a physical theory is how many people are working on it (he also points out that about 500 people go to Strings 200X), not whether there is any experimental evidence for it. The examples he gives range from cases where there is zero experimental evidence, and probably never will be any (extra dimensions, supersymmetry) to ones that it is very plausible we will soon see evidence of (Higgs boson, gravitational waves) to ones that arguably we already have some evidence for (cosmological constant).

He notes that gravitational waves were predicted in 1916 and have yet to be confirmed, that string theory is more ambitious than GR so it should take longer to confirm, and that one should only really start counting in 1995, when M-theory came along. So I guess his prediction is that by 2074, we still won’t yet be anywhere near confirming string theory. Like many string theorists, he make highly tendentious claims about the relation of the standard model to experiment, writing:

decades [were] required to knock the standard model into a shape that could be confirmed by experiment

I assume he’s not talking about the QCD part of the standard model, which was born in 1973, already making verifiable predictions, and within ten years had accumulated a huge amount of evidence in its favor. The electroweak theory was first written down by Weinberg and Salam in 1967, and by ten years later the evidence for it was overwhelming. I suppose you could try and argue that the history of attempts to put together the standard model go back to Glashow in 1960 or Yang-Mills in 1954. Even using 1954, it was 19 years later that the full standard model was in place with a lot of experimental evidence already there and more pouring in. And that period would quite likely have been shorter if most of the theory community hadn’t given up on QFT and been working on the bootstrap, dual models or string theory during that time. In the case of string theory, taking Veneziano in 1968 as a starting point, nearly 4 decades later there is not a glimmer of a piece of experimental evidence for string theory. Comparing the history of the standard model to the history of string theory is just absurd.

On another recent topic, the New York Times finally today carried an obituary for Raoul Bott.

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54 Responses to Follow-Ups

  1. Urs says:

    I will mention that the key is that in a Lagrangian density over 8-dim spacetime, the dimension of fermion/spinor PSI is 7/2 (as opposed to dimension 3/2 over 4-dim spacetime), and 8 fermion particles x 7/2 dimension = 28 = 28 gauge bosons x 1 dimension.

    If this is really more than numerology it might be interesting. It’s hard to say, for me.

    sixteen of the dimensions of bosonic string theory are transmuted from bosonic to fermionic by a dynamical mechanism that involves the decay of the tachyonic degree of freedom

    That’s what one would hope. What concrete evidence do we have?

    I am somewhat saddened that Lee seems to mostly run around talking about relatively general topics such as background independence and Lenny seems to be running around Lost in his Landscape. Such topics are easy to use as PR hype for the public and funding agencies, but in my opinion they are nowhere near as useful as the hard work of doing some detailed calculations

    Well said. We definitely agree on that.

    It’s not that there is nobody out there looking hard for new grand (algebraic) structures. P. West and H. Nicolai come to mind with their attempts to integrate everything into E10 and E11. Judging from the abstracts of Nicolai’s papers there seems to be slow but steady progress and mounting evidence that indeed all of 11D supergravity is (a small subset) of the geodesic motion on something like exp(E10/K(E10)).

    But things like that are certainly, and unfortunately, in the minority at the moment.

    If you make John Gonsowski write a comprehensive and coherent pdf exposition of your ideas, I promise to take a detailed look at it. More importantly, others might, too.

  2. ksh95 says:

    If you make John Gonsowski write a comprehensive and coherent pdf exposition of your ideas…

    I second that, especially the part about coherent.

    As to some of the associations that I make seeming strange or unusual, that is one of the topics that I discuss in therapy with my psychiatrist. So far, his diagnosis seems to be that the unusual associations are not problematic, although depression is a problem for which I am undergoing therapy.

    Whoa, slow down there Tony…Way to much information. You were on a roll, why didn’t you quit while you were ahead? You wrote one paragraph to many.

  3. woit says:

    This discussion of Tony Smith’s ideas is way off topic, and this kind of thing gives lots of people the idea that this is a forum for discussion of their own work. I then have to spend increasing amounts of my time deleting people’s comments in order to keep this comment section from turning into sci.physics. Please continue this discussion with Tony privately or in some other forum.

  4. Tony Smith says:

    Urs, “… sixteen of the dimensions of bosonic string theory are transmuted from bosonic to fermionic by a dynamical mechanism that involves the decay of the tachyonic degree of freedom …” is a direct quote from Lee Smolin’s paper at hep-th/0104050, so he would be the one for you to ask: “… What concrete evidence do we have? …”. It could probably be answered with some of the hard calculations that in older times would be assigned by someone like Lee to his grad students / postdocs / etc.

    Maybe (and this is just speculation from one who has been out of academia for a long time) grad students / postdocs / etc nowadays don’t see doing such assigned hard work as “the” way to advance, but instead just write a lot of relatively shallow “me-too” papers, or even follow the example of Lubos and advance by acting as mindless advocates (a la talking head political spin-masters on Fox News etc) of whatever the powers-that-be say.

    As to writing a “comprehensive and coherent pdf exposition of …[ my ]… ideas”, I wouldn’t demand that of anyone, much less a friend like John Gonsowski. The closest thing to such a single pdf file might be the one on my web site at which is about 550 KB, and about 65 pages, in size. It has my ideas up to around 2003, but it is not in LaTeX, and it does not cover my more recent calculations of neutrino masses and mixing angles and of the Dark Energy : Dark Matter : Ordinary Matter ratios observed by WMAP.

    Tony Smith

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