Certain things cannot ‘simulate physics’. You would need a root component that is capable of stimulating physics like a collision sphere and then everything beneath it will also simulate physics. As for communicating between actors, yes, casting should work fine assuming you get the proper reference object type. Interfaces, event dispatchers and straight casting could get you what you want. If you need help implementing this check out video #1, 25 and 26 in the link below. They are most relevant to what you are trying to do.