I was impressed how in R. Geroch's book, Mathematical Physics, category theory is used to unify so many different branches of mathematics. Is there a single framework that, in a similar way, unifies many or all branches of physics? If so, what are some good resources for learning it? So far, the closest I have seen is perhaps the mathematics of linearity, of multi-linear maps and objects on which such maps act. Is there something better? It would be great to be able to see each area of physics as instantiating some one thing.