Communication theory is far too narrow a subfield.

Physics has a lot to say about this. Physicists have done a lot of information-theoretic analysis of the laws of physics, and physics-theoretic analysis of information theory. Information theory can no longer be disentangled from the physics itself. Meaning, what information processing tasks (including but not limited to communication tasks) are possible and with what complexity depends on the laws of the universe we live in. And conversely, which universes are even possible (those with "reasonable" laws) are constrained by the theorems of information theory.