A cat and a flask of poison are enclosed together in a hermetically sealed opaque container. If the flask is broken, the cat is killed by the poison. Breakage of the flask is triggered by the discharge of a Geiger placed behind one of two holes made in a screen which is irradiated at the front by abeam of electrons. It is supposed that the beam is so weak that only one electron passes through the screen during the experiments. According to QM, the cat should be dead-alive before the experimenter observe it But, can't the cat observe the flow of electrons and make every possible route collaspe into one? Then the cat will not be dead-alive. I hope you guys can give me some advice. Thank you.