I have read material on several parts of physics. The material I have read on string theory is among the worst stuff I have read. The people who write about string theory don’t seem to be particularly interested in quantum theory or general relativity, or in explaining the problems they’re trying to solve. Their material reminds me of this quote from DD in a talk he gave called “Apart from universes” [1, 2 Chapter 18]:
There’s a related and even worse spanner in the works of elementary particle physics: particles (or fields, strings, or whatever) are supposed to be fully quantum-mechanical entities. But the people who work on them only ever construct classical, single-universe theories. Why? Because they think that the quantum part of the theory necessarily has to be trivial. It is assumed that in order to discover the true quantum-dynamical equations of the world, you have to enact a certain ritual. First you have to invent a theory that you know to be false, using a traditional formalism and laws that were refuted a century ago. Then you subject this theory to a formal process known as quantization (which for these purposes includes renormalization). And that’s supposed to be your quantum theory: a classical ghost in a tacked-on quantum shell.