I wanted to check my understanding of why exactly the whole "cat in a superposition of alive-and-dead" would never actually happen in the situation described in the Schrödinger's cat thought experiment. These are a few different reasons I had come up with and I want to ask if they are correct:
The cat is not in a vacuum, its state - alive or dead - is constantly being measured by the air around it
For that matter, the cat is made up of billions of particles - it is constantly measuring its own state itself.
"Alive" and "Dead" are vague and involve too many things to describe - they are not simple, perfectly discernable and definable states the same way "spin up" and "spin down" or "decayed" or "not decayed" are.
The crux of the thought experiment is that the poison that kills the cat is only released when a specific isolated atom decays - since the atom is in a superposition of decayed and not decayed, "before measurement" (opening the box) the cat must also be in a superposition of alive and dead. But for the poison to only be released when the atom decays there has to be some detector checking whether or not it has decayed so it can activate the poison: it is measuring the state of the atom. So wouldn't the "decayed or not decayed" wavefunction collapse into either just decayed or just not decayed right there and so never involve the cat?