AI could discover candidate novel physics without autonomously operating new physical experiments, and humans or instruments can later independently validate the result. This is analogous to how Einstein developed theories whose predictions were confirmed by experiments and observations only years or decades later.
Do we have any examples of an current day AI system introducing a novel concept or perspective. We've got plenty of counterexamples discovered and some theorems proven, but afaik nothing analogous to a new definition.
It could be a good theoretical physicist. Actually it could be a good experimental physicist as well since senior experimental physicists use grad students for the manual labor.