One of the major criticisms of string theory has to do not with the theory so much as with theorists. The argument is that they are forming something of a “cult” of string theorists, who have bonded together to promote string theory above all alternatives.
This criticism, which is at the heart of Smolin’s The Trouble with Physics, is not so much a criticism of string theory as a fundamental criticism of the way academic resources are allocated. One criticism of Smolin’s book has been that he is in part demanding more funding for the research projects that he and his friends are working on, which he feels are undersupported.
String theory is the most popular approach to a theory of quantum gravity, but that very phrase — most popular — is exactly the problem in the eyes of some. In physics, who cares (or who should care) how popular a theory is?
In fact, some critics believe that string theory is little more than a cult of personality. The practitioners of this arcane art have long ago foregone the regular practice of science, and now bask in the glory of seer-like authority figures like Edward Witten, Leonard Susskind, and Joe Polchinski, whose words can no more be wrong than the sun can stop shining.
This is an exaggeration of the criticism, but in some cases, not by much. String theorists have spent more than two decades building a community of physicists who firmly believe that they are performing the most important science on the planet, even while achieving not a single bit of evidence to definitively support their version of science as the right one.
John Moffat has joined Smolin and Woit in lamenting the “lost generation” of brilliant physicists who have spent their time on string theory, to no avail. He points out that the sheer volume of physicists publishing papers on string theory, and in turn citing other string theorists, skews the indexes about which papers and scientists are truly the most important.
For example, there is a rumor that Edward Witten has the highest h-index of any living scientist. (The h-index is a measure of how often papers are cited.)
If you look at it from Moffat’s point of view, this is not necessarily a result of Witten being the most important physicist of his generation, but rather a result of Witten writing papers that are fundamental to string theory, and, in turn, are cited by the vast majority of people writing papers on string theory, which is a lot of papers.
Now the problem with this approach when it comes to Witten specifically is that it’s very possible that he is the most important physicist of his generation. Certainly his Fields Medal attests to his position as one of the most mathematically gifted.
But if he is an important physicist who has helped lead a generation of physicists down a road that ends in string theory as a failed theory of quantum gravity, then that would indeed make for a “lost generation” and a tragic waste of Witten’s brilliance.