Why I am REALLY disappointed about string theory

[smoit]

Just to add to the above, family replication is just one manifestation of a topological complexity which leaves its imprint in the particle physics spectrum. This is part of a very generic trend, namely the multiplicity of particles with similar or identical properties in a given string compactification. The other examples are: multiple geometric moduli, multiple axions, multiple non-Abelian hidden sectors, multiple U(1)s. This multiplicity looks rather mysterious within a strictly 4-dimensional theory but occurs generically in string theory. Particularly interesting and potentially testable is the idea of multiple species of string-theoretic axions, so-called "String Axiverse", where the QCD axion is just of of the many http://arxiv.org/abs/1004.3558" .

 

[atyy]

http://arxiv.org/abs/1004.3558"

Bosenova

 

[tom.stoer]

Tom, the answer to many of your questions is 'No one knows'. Perhaps it would be best if you focused on one question, formulated into a sufficiently precise statement (by doing a few minutes of self research to get the basics) and asked them one at a time.

In-depth clarification of individual details was not my intention for this thread. I know some of these results, either from papers or from discussions here in this forum, sometimes with active string theorists. And if I want to understand more regarding one specific problem I will ask this question in an own thread.

My intention was different: I started this thread with a rather broad and generic criticism regarding the string theory research program as a whole. A reply should be equally broad and generic leaving out many interesting details, but it should address my generic criticism and of course summarize gain knowledge achieved during this discussion. Just as an example: it is not relevant that heterotic string theory has topological invariants which can be identified with fermion generations; that's interesting mathematically but irrelevant physically as long as we do not know "why heterotic string theory instead of something else" and as long as we have no good reason why the results should be three. But the find that "string theory" is not like QCD but more like "gauge theory", i.e. a framework instead of one individual theory, combined with the idea that string theory harmonizes different theories (like gauge theories, SUSY-GUTs and SUGRAs) into one single theory with different vacua is a very deep result and profound knowledge.

So my idea was to let one expert answer the generic questions I started with and to summarize the main achievements, both of the theory and of course of our common understanding developed together as part of this discusson. This seems to be fair.

If the answer to some question is "we don't know yet", then this answer should be part of the reply, why not?