15 March 2006

Ideology, sociology and psychology of strings

There is a paper by Bert Schroer, String theory and the crisis in particle physics, where it is claimed that the ideologically dominated string community is causing a huge crisis in high energy physics. I think that is a good exercise in psychology (even if you are not a psychologist) to try to understand what is behind this paper.

First of all, Bert works in axiomatic field theory not in string theory, so his comments are not of a technical nature. It should also be clear that he thinks that quantum field theory is not a closed subject. I think we all agree on that but not for the same reasons. He claims that there should exist an intrinsic formulation of QFT in which the concept of fields is not mandatory. That is a good topic for research. It is in the same foot as the search for a unique formulation of string theory. It may exist or not but it does not prevent that progress in understanding the theory can be gained by other means. The reason I think QFT is not complete is the lack of a full understanding of its non-perturbative sector, something that author fails to appreciate and that axiomatic field theory is far from even beginning to address.

So let us go back to his paper. His first argument against strings are citations found in discussion groups and texts for layman, like "Superstring/M-theory is the language in which God wrote the world". This hardly can be taken as a serious argument, and Bert knows that, so it seems that he is just warming up the reader. Then his main argument goes like the quantized strings are not really quantum strings because the string excitations are localized around the string center of mass. And he concludes that all this is just "a trick to find a Lagrangian packing for the dual model with its infinite mass tower". Well, anyone who has calculated the spectrum of free strings knows all this. And it seems that all critics of string theory go only to the point of studying free strings and to presume they know it all. There are other comments on the physics of string theory but they are not technical and do not deserve any consideration.

So let us look now at the ideological side to pin down what is behind all this. He lists what he considers to be five big problems. The first is that young people do not know the conceptual axioms of field theory and that he can not talk to them because they only know string theory. Well, surely young people will study axiomatic field theory, if that is relevant for what they are doing, but older people should also study strings if they want to discuss the important issues of today. If you are too old or too lazy to study new things what can be done?

He then complains that the editorial boards of high energy physics journals are full of string people, and that there is an "ideological battle between two globalized groups rather than a critical analysis of its contents", probably refering to submited papers. Is this just another way of saying I can not publish my papers in good journals? After all, if you look at editorial boards you can send your papers to non-stringy physicists. His third point is a complain about the undergraduate course in string theory given at MIT. As we all know young students want to learn string theory and there is nothing wrong with that. If that can be done seriously, why not? What really happens is that undergraduate students keep asking questions about many things. What do you do when they ask you about strings if you do not work in strings? This is tricky, very tricky.

His fourth point is more interesting. As said before he does not consider quantum field theory to be a finished subject and string theory is worse since its "structural properties" are not known (I assume that by structural properties he means an intrinsic formulation). He then says, let us assume that the AdS/CFT correspondence is true and since we know the quantum field theory side we could use the correspondence to find out the "structural properties" of string theory. What a good idea! He just doesn't realize that this is happening, and in both ways. We can learn new things about quantum field theory as well as about strings. In fact, he fails to recognize that what he calls "structural properties" of string theory is named M-theory and string field theory.

Finally, his last point is about the future of particle physics. The problem of having so many string theorists getting jobs and appearing in the media worldwide. Well, this is happening for a long time now, at least since the past century. Relativity, quantum mechanics, atomic bombs and many other topics generated great curiosity in the public and received attention in the media. What can be done if no journalist is looking for you? Do you have any interesting thing to say?

In the second part of the paper Bert tries to convince the reader that we must abandon string theory and go back to quantum field theory, but in his way, to the old fashioned S-matrix bootstrap approach of the 60's! He also claims that the mathematical issues of field theory will be solved soon (probably by him or his group) and criticizes strongly any geometrical approach to field theory. Reading this looks like general relativity is in the wrong track and leads nowhere. Also, the geometrical Atiyah-Witten work is also condemned in his paper. It would be very interesting, however, to see axiomatic field theory saying something about anomalies. Or even about asymptotic freedom. And we are not talking about properties of some formulation of field theory but about Nature itself.

So now we have a clear psychological picture of the paper. Full of prejudices and lack of understanding of what are the main goals of QFT and string theory and very revealing about the author's personality. The only crisis after all is in the author's understanding of the modern world. Unfortunately he is living in Brazil and we have to be sociable and civilized.

Just in time, Lubos and Woit have posts on Bert as well.

1 comment:

urs said...

Since I don't have a blogger account, regard the fpollowing link as a manual trackback: