Fig. 9
Schematic diagram illustrating the Schrödinger's Cat gedanken experiment. A sealed and insulated box (A) contains a radioactive source (B) which has a 50% chance during the course of the "experiment" of triggering Geiger counter ( C) which activates a mechanism (D) causing a hammer to smash a flask of prussic acid (E) and killing the cat (F). An observer (G) must open the box in order to collapse the state vector of the system into one of the two possible states. A second observe r (H) may be needed to collapse the state vector of the larger system containing the first observer (G) and the apparatus (A-F). And so on ...