Thursday, December 8, 2011

Duff defends string theory

String theorist M. J. Duff has just posted String and M-theory: answering the critics. It is a followup to this 2007 debate transcript and podcast. I noted before that he badmouths those who are skeptical about the "academic consensus of superstrings".

Motl is annoyed by this footnote, and wants an apology:
7 I do not share Lubos Motl’s extreme views on politics, global warming, and sometimes not even string theory. However, he occasionally has some good physics summaries, including a recent one giving a nice history of the triumphs of unification [26].
So Duff in not only aggressively defending the academic consensus on superstrings, he is defending a supposed academic consensus on other leftist political matters.

Motl is right to be offended by this cheap shot. I cite other blogs all the time, but I don't bother to disavow opinions expressed on those blogs about other subjects. Duff acts as if he might demonstrate allegiance to the dominant paradigms, or else he might lose the respect of his colleagues.

If you think that string theory might have accomplished something, then go ahead and read Duff. It is pitiful. Duff attacks Smolin for what his publisher said, but admits that his own publicist has put out exaggerated press releases.

Peter Woit also slams Duff's article.

Duff defends string theory with silly statements like this:
Yet support for superstrings and M-theory is based on their ability to absorb quantum mechanics and general relativity, to unify them in a mathematically rigorous fashion, and to suggest ways of accommodating and extending the standard models of particle physics and cosmology. No religion does that.
Duff says that critics must be stamped out because they threaten funding, and because of a comparison to how a leftist politician blames vaccine critics.

The argument for superstrings hinges on a flawed historical example:
The job of theoretical physicists is two fold: first, to explain what our experimental colleagues have discovered; and second, to predict phenomena that have not yet been found. The history of scientific discovery shows that progress is achieved using both methods.

Quantum theory, for example, was largely driven by empirical results, whereas Einstein’s general theory of relativity was a product of speculation and thought experiments, as well as advanced mathematics.
But this story is wrong, as I explain in my book. Special relativity was discovered by Lorentz and Poincare based directly on experiments. Poincare was the first to apply the theory to gravity, and used it to partially explain an anomaly in Mercury's orbit. Einstein's main contribution was to extend Poincare's argument. Einstein later denied that he was motivated by such empirical issues, but we know from his letters that he was concerned with Mercury all along.

It is a big myth that Einstein revolutionized physics from speculation, thought, and math, and no empirical results. This myth is always used to justify bogus research programs like string theory.

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