George - would it be true to say that it is the probability of an observer finding the cat in a particular state rather than simply the probability of the cat being in that state?

If that is the case then Mr First observing the cat will have no effect on Mr Second's probability function.

Oh, actually it would as Mr Second could find the box empty due to the action of Mr First. So, in that respect, Mr First has affected Mr Second's probability wave as prior to Mr First's involvement the cat could only have been in 2 states - alive or dead - and now there are 3 possibilities.

So if you were calculating Mr Second's probability function with passing time, you wouldn't be able to factor in the probability of the cat not being there if you were unaware that Mr First had opened the box.

Prior to Mr First opening the box the cat was alive & dead at the same time. After his involvement the cat is alive, dead, and gone at the same time. I'm not sure if that's important or not. [

]

P.S. If the box was empty, Mr Second still wouldn't know if the cat was alive or dead.