Theories of Everything

(( This figure comes from a document on arXiv, which is not peer reviewed. Documents on arXiv should be viewed as "entertainment only, any any resemblance to real science or mathematics, living or dead, is purely coincidental" until the documents have been vetted by the community. That said, this flowchart of formal systems amuses me. I also find the notion that the existence of a mathematical description of a physical system somehow, philosophically, implies the existence of such a system, entertaining, in an almost religious sense. ))