[yetihehe]

So, how "it changes from state we don't know to a different state after measurement" differs from "we don't know what state it is, but after measurement we know"? How do you know state changes after measurement when you don't know which state it is before measurement? Does it really change, or do our knowledge of that state changes? That's why I say that state doesn't change, we only know what state it is after measurement.