It is not uncommon to have multiple interests and wonder about other options at any age. The funding is usually an issue. The nice thing is there are always options but the first priority has always been to the current career goals, the education required to maximize the career options with one's education, and establish oneself within the one field first. Classes in the meantime towards one's passion are an option, especially if trying to get established in another field. Knowledge always enhances us to apply to whatever field we are in. HOWEVER, if not liking the current field, change it; it's not worth pursuing education for something you are not committed to and passionate about. If do like the current one, the further education will help you in your field, and then consider pursuing the physics once you are established in the other.