The lack of any serious (Lubos doesn’t count) response to my book from string theorists since its appearance in the UK a month or so ago has begun to surprise me a bit. I was also suprised at how weak the defense of string theory was that the Wall Street Journal’s Sharon Begley put in her recent article. It seems that she did talk to some string theorists, but couldn’t get much usable from them (one supposedly told her that the best argument for string theory was the anthropic landscape). Peskin’s argument that string theory’s biggest success is its “explanation” of the number of generations was evidently the best he could come up with, although it’s obviously very weak.
I’ve heard that the WSJ has gotten some correspondence about this, with Jacques Distler writing in to complain about the article. In one letter from him (also signed by his two collaborators), he claims that Smolin is wrong to say that string theory is not falsifiable, since Distler has a recent paper called Falsifiying String Theory Through WW Scattering.
This paper was discussed extensively here. You can make up your own mind about it, but it’s undeniable that the calculations in the paper don’t involve string theory at all (Distler’s two co-authors are not string theorists). Pretty amazing trick to show that a theory is falsifiable without actually using the theory at all.
There are two obvious problems with the claim in the title of the paper, the first is that when one says a theory is falsifiable, one is talking about the characteristic predictions of the theory, and that’s not what the paper is about. The second is that “string theory” is an ill-defined term, and many versions of “string theory” don’t satisfy the assumptions of the paper (one of the co-authors admits this in the comment section). To fudge his way around this, in the letter to the WSJ, Distler refers to “the canonical definition of string theory” as opposed to “string theory”, although he provides no reference to what this is. Putting “canonical definition” and “string theory” into Google doesn’t turn up anything relevant.
It will be interesting to see if a referee can be found who will go along with allowing the “falsifiying string theory” claim. Most physicists, string theorist and not, that I’ve talked to about this think it’s way out of bounds. It seems to me pretty amazing that Distler would choose to take this case to the Wall Street Journal.
We’ll also see if the WSJ publishes the letter, if not I’ve asked one of the co-authors if they’ll let me publish it here.
I could certainly do a better job of defending string theory than the people Begley talked to. The strongest argument string theorists have is clearly the one that they have “the most promising approach to quantum gravity”. The problem with this is that there are plenty of people who disagree, especially those who do LQG. This is the reason that Distler has been on an anti-LQG campaign throughout the blogosphere recently. His latest posting is about this, with comment section featuring the always incoherent Lubos Motl, and the trademark Distlerian sarcastic sneering at people he disagrees with, e.g. the following comment on a paper by Thomas Thiemann:
I suppose that it is only Thomas’s natural modesty that prevented him from submitting this paper for the Clay prize.
In the first comment, someone quotes from my book something I have to say about the issue being discussed in this posting. For the record, I’m no expert on LQG, and can’t judge exactly how close they are to having a fully satisfactory quantum gravity theory, but my impression is that what they are doing is a more promising approach to quantum gravity than string theory, and the fact that they are convincing more people about this is what is getting Distler and others very worked up. I also don’t think either LQG or string theory has made any headway on the problems of the standard model, although several orders of magnitude more effort have gone into the string theory approach.
Since Distler has a whole posting and ongoing discussion in his comment section about this and I’m no expert, if you want to discuss LQG, its problems and prospects, or comparisons to string theory, please do it there, not here.