Today, the grand challenge of theoretical physics is unifying quantum mechanics with gravitation. Based on this historical progression of examples, I predict that the correct mathematical theory of quantum gravity will break all previous records in being difficult to interpret. Suppose that on the eve of the next quantum-gravity conference, our friend the genie broke into the lecture hall and scribbled the equations of the ultimate theory on a blackboard. Would any of the participants realize what was being erased the next morning? I doubt it!
