A cat is placed in a sealed box. Attached to the box is an apparatus containing a radioactive atomic nucleus and a tail removing mechanism. The experiment is set up so that there is exactly a 50% chance of the nucleus decaying in one hour. If the nucleus decays, it will emit a particle that triggers the mechanism, which removes the cats tail and creates something which is not a cat. If the nucleus does not decay, then the cat remains a cat. According to quantum mechanics, the unobserved nucleus is described as a superposition (meaning it exists partly as each simultaneously) of "decayed nucleus" and "undecayed nucleus". However, when the box is opened the experimenter sees only a "decayed nucleus/not a cat" or an "undecayed nucleus/still a cat."
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A cat is placed in a sealed box. Attached to the box is an apparatus containing a radioactive atomic nucleus and a tail removing mechanism. The experiment is set up so that there is exactly a 50% chance of the nucleus decaying in one hour. If the nucleus decays, it will emit a particle that triggers the mechanism, which removes the cats tail and creates something which is not a cat. If the nucleus does not decay, then the cat remains a cat. According to quantum mechanics, the unobserved nucleus is described as a superposition (meaning it exists partly as each simultaneously) of "decayed nucleus" and "undecayed nucleus". However, when the box is opened the experimenter sees only a "decayed nucleus/not a cat" or an "undecayed nucleus/still a cat."