Quantum Mechanics - Is Everything Just a Way Function?

In classical mechanics, we can think of every different place or piece of the world as having its own state. But quanta mechanics tells a different story - there is not a wave function for the earth, and another one for the ferma in space. And so on throughout all space. There is only one wave function forthe entire universe at once. If that's right, why does it seem to us that the way funcon collapses when we observe them?