I have what is probably a very basic question about the Schrödinger's cat thought experiment. As I understand it, in order for the counter tube to break and release the deadly poison, the Geiger counter must measure whether or not an atom decays. So, why doesn't that measurement collapse the wave function? And, if that measurement isn't enough, why wouldn't the cat's observation of poison or no poison collapse the wave function? And if I'm incorrect about the Geiger counter being a measurement, then would I be correct to assume that by the same logic, if you conducted a double slit experiment, and you put photon detectors by both slits, but you never actually look at the wall on the other side, that Schrödinger would suggest that the photon detectors by themselves were insufficient to collapse the wave function? I get that Schrödinger used this thought experiment as a reductio ad absurdum, but I don't understand why the Copenhagen interpretation would require the cat to be in some undead quantum state.