The system is made of a box, a cat, and a radioactive nucleus that, when it emits a particle, triggers a mechanism that emits poison gas into the box, killling the cat. At any given moment one may open the box and see if the cat is dead or alive. But what happens while the box is closed? The emission of the alpha particle is a quantum effect, with a probability of occuring so, before the observation, the system of the nucleus and the alpha particle it will emit is a superposition of the nucleus in the initial state, and the nucleus plus the alpha particle. Only the observation (opening the box) "collapses" the wave function in one of those two states. Is it the cat also a superposition of "dead cat" state and "live cat" state?
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