Courses of study from any of Physics, Mathematics, Engineering, or other sciences can support each other. A physicist may have more mathematics courses credited than were necessary; or a mathematician could have more Physics course credit than necessary for his mathematical work. Realize that faculty from one university department may teach classes/courses in another university department. I remember a few like that. One professor who taught computer science where I went also taught some Physics courses. Which department was he in officially? No memory, but his instruction was fairly good in both.
I mean can a mathematic professor take the certain highest degree (like BA, MA or PhD) in Physics while taking PhD in Math? Wonder if that is possible. I'm interested in becoming one because I'm so delved into such subjects.