My question is about a "philosophical" implication of the copenhagen interpretation:
Schroedinger's cat sits in a box in a superposition state, until it interferes with the rest of the universe and decoherence occurs. The whole universe, except this box, interferes with itself and thus enables a "common ground truth" to form, such that we can say: "this cat is in a superposition, we're not".
But everything inside the box is interfering with each other as well, disconnected from the rest of the universe, and thus enables an alternative "common ground truth", such that the cat would say: "the rest of the universe is in a superposition, I am not".
So how are we to say that anything is or isn't objectively in a superposition?
