What if we treat you the same way we treated everything in the box? Well, in that case, when you look in the box, you’re interacting with it—which means you get entangled with the shared wave function of the box and everything in it. So now we have an even bigger wave function, still with two parts: one where you see a dead cat and a smashed vial of poison, and one where you see a happy cat and an intact vial. Which part of the wave function is real? Everett, remembering Wheeler’s advice to take the consequences of physical laws seriously, answered that both are real. There’s no way to pick
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