Thursday, January 27, 2005 ... Deutsch/Español/Related posts from blogosphere

Strings at a university in Boston

Peter Woit has pointed out an interesting article about the opponents of string theory at a certain university in Boston. The article was composed by the students of that university.

You know, in the 1960s and 1970s, particle physics had a lot of new experimental data, and the progress in theory followed. It had to be a cool period. The physicists were often inspiring and independent personalities, and most of us admire them. Shelly Glashow is a very interesting person - and I like his common sense and other things.

By the mid 1970s, however, the Standard Model was established. It was clear from the very beginning that despite its nice features, it was not the final theory of everything. What is there beyond the Standard Model? No truly exciting, purely old-fashioned directions to further progress have been found for nearly 30 years or so. Since the 1970s, it was becoming clear that string theory was containing all the good, deep, and most of the interesting answers and ideas - supersymmetry, extra dimensions, dualities, various new types of transitions, holography, new non-perturbative effects, non-commutative geometry, and so on. The progress in the "conventional" directions slowed down significantly.

In the mid 1980s, the first superstring revolution exploded. In 1985, Cumrun Vafa got his PhD at Princeton and moved to Harvard. He's been the right man with the right ideas who appeared at the right time and the right place. The exciting period of the mid 1980s in which he started may have contributed to his amazing success; however, it is probably more important that Cumrun is a kind of genius.

Although there have always been very interesting people at Harvard, Cumrun quickly became the key theoretical physics brain at Harvard. He became - and still is - a leader of topological string theory and other directions within string theory. Once again, Shelly Glashow is a very nice and interesting person who has done a lot for physics. Meanwhile, Cumrun was generating a lot of exciting papers in string theory. Peter says that Cumrun "managed to marginalize Glashow". Well, yes, Peter is right. But the process how someone marginalizes someone else in physics is not based on ad hominem attacks summarized as a blog article - an article that tens of ignorants support by their comments: the actual mechanism was that Cumrun simply generated much more interesting physics than anyone else in the department.

At some point, string theory has become the mainstream direction in fundamental physics. It's not surprising that Cumrun could expand the string theory group at Harvard. String theory was migrating to the standard, well-known top universities. Shelly Glashow did not like this development and he moved to another university in Boston whose name I don't find terribly important in this discussion; greetings to Andrew Cohen who became a leading peacemaker in the article. ;-) Meanwhile, string theory has generated a lot of new exciting results.

Shelly did not want the same history from Harvard to be repeated at his new university in Boston. Therefore, he imposed a new policy that all physicists in his new department must believe that string theory does not exist - or does not belong to the physics departments. He's extremely successful in his new task: about 100% percent of his colleagues are believers, as the article explains. Meanwhile, string theory generates ten more essential links between the concepts in physics. Shelly Glashow even believes that his new university in Boston became (or remained?) one of the leaders in the field. Another reason why we like Shelly is that he is able to be very entertaining.

Let me make some things clear: right now, in January 2005, the theoretical physicists can't agree about the direction in which the field should go. Most of us don't see a single "thrilling" direction in front of us; Cumrun definitely agrees. Virtually all of us would be happy to find some connections with experiments, but no one knows how to do it. And the start of the LHC in 2007 will certainly be important. Be sure that most of us are dreaming about some totally new idea or concept that will "click" in our brains and revolutionize the field once again. The more such an idea differs from the insights we already know, the better.

But the previous paragraph does not change anything about the fact that we have extremely good reasons to think that the new idea will be a new way to look at string theory. It may modify our approach to some questions - such as the relations between the different vacua in the "landscape" or our understanding of supersymmetry breaking and its consequences - but at the same moment, it's highly unlikely that such a new insight could change something about the paradigm that physics of our Universe is connected to physics of string theory in 10 dimensions and M-theory in 11 dimensions.

The idea that string theory will go away completely is a childish idea. Different departments have their rights to pursue their strategies; the strategy to deny the existence of the dominating segment of theoretical physics in the last 20 years not only seems foolish to me: it has been an unsuccessful one. Definitely, you will agree unless you consider adding new digits to the 3 x 3 neutrino mass matrix to be a more exciting activity than understanding of gauge theory via gravity. Incidentally, Sheldon Glashow cites the Little Higgs model as an example of a development in which his new university played an important role. That's amusing especially because most of the authors of most of the important papers about the Little Higgs model were from Harvard and the person from the other university in Boston who played an important role is exactly an exception among his colleagues - a kind of friend of string theory - and moreover, he was visiting Harvard while the papers were written.

Peter likes to think about Cumrun's diplomatic term "childish idea". I am sure that Sheldon Glashow would agree with me completely that we have enough experimental evidence (remember Einstein and quantum mechanics and his failed attempts to construct a classical unified theory?) that a Nobel prize does not save one from childish ideas.

If the LHC sees the Standard Model with a single Higgs only, the whole particle physics will suffer - and string theory will suffer, too. If some stringy phenomena are seen - such as supersymmetry or even extra dimensions (or mini black holes) - string theory will celebrate and the string theorists will become much more interested in phenomenology - which will be the most natural development in such a situation. If some weird non-stringy physics is seen, the support for string theory in the physics departments will be reduced, but I am sure that people will continue to study this amazing mathematical structure.

Concerning "The Elegant Universe" on PBS. Cumrun liked it a lot, and I liked it, too. It was a great show that shows what's really exciting in cutting-edge physics. It had some bugs - for example, it did not mention Joel Scherk and other important people - but the overall quality was very good. To say a compensating comment: Andy Strominger found many pictures in it naive, and he even said that Shelly Glashow gave a more reasonable assessment of the situation than the advocates of string theory! ;-) Cumrun described the show as "something in between physics and video games". His sons were intrigued by this show, too.

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snail feedback (4) :

reader Anonymous said...

Very nice description -- and incidentally, it's quite politely written. Good job.

reader Paul Frampton said...

I would disagree with the statement "No truly exciting purely old-fashioned directions to further progress have been found for 30 years". As a phenomenological model builder it is irresistible to ask the question: Why is it obvious that if the LHC discovers new physics beyond the standard Higgs that it must involve drastically-new theoretical principles? Is there any reason that it cannot be simply a larger gauge group than 3-2-1 and correspondingly larger matter representations? An example is my 331 model published in PRL 69,2889 in 1992. This model offers an explanation of why there are three generations and predicts additional gauge bosons and quarks.

reader Quantoken said...


Please go defend the good name of Harvard, since I have posted why a fraud was committed on Harvard campus of the so called Harvard Tower Experiment:

This has nothing to do with the correctness of GR. I firmly believe the equivalence principle is correct and so is GR. But doctoring data to outfit what one believes in, is a totally different story.


reader Anonymous said...

I'm afraid that, while his book was a great success, everyone I know (who has a math/physics background, but has no clue what string theory is about) found Brian Greene's two part TV series "The Elegant Universe" extremely boring. It was very slow, very repetitive, everyone spoke so slowly, and kept on saying the same things over and over again.

I am trying to promote string theory at my university, and Greene's program was not helpful at all. He pitched at a too low intellectual level, and gave an impression of the subject that was far from "exciting".

I wonder if anyone else has the same experience.