Where is the line between these two subjects. I understand that I may be asking an unanswerable and highly studied question. I understand that in the quantum world everything is based on probability. But when looking at things at our perspective we never see this probability. Everything is based on cause and effect. Why doesn't some of our equations take into effect these small probabilities no matter how minute they may be? Is this really what it means to connect quantum theory and relativity as the theory of everything? I supposed I just don't understand what the barrier between the two theories are.