Let me repeat in case it is not clear from the other answers that: Theoretical physics questions are on-topic on Phys.SE, and more than welcome. All$^1$ Q&As from TP.SE have been transferred in 2013 to Phys.SE and most (if not all) are open for new answers. -- $^1$ Except for a handful or two, which were migrated to TCS.SE.

Only top voted, non community-wiki answers of a minimum length are eligible