"Anyone who has not been shocked by Quantum physics has not understood it," said N. Bohr. Now I am confused by the interpretation of the state of Quantum mechanics (QM). I still remember my teachers told me in class that the prediction of QM is valid only for large enough experimental result. That is to say, QM doesn’t discuss the individual level of the experiment. For example, we can get the interferential pattern in the double-slit experiment only after enough particles have gotten the screen. And it is consistent with the result of QM. But it is meaningless to ask how one particle goes through the slits. Today, I read a paper which discusses the individual experiment in QM. So I am confused. Can we discuss what the state of Quantum mechanics (QM) is? Thank you!