Here is my understanding (which I hope others will correct if it is mistaken).
Suppose I have a duplication machine, with an in slot and two out slots. You drop something in the in slot and two identical versions of it are produced in the out slots. They are down-to-the-atom identical at the moment of production—there is not an ‘original’ and a ‘copy’, there are ‘two originals’.
Now I position the machine so that one out slot drops into a blue box and the other into a yellow box. I drop you into the machine. As you tumble down the in slot, what is your subjective expectation about what colour box you will end up in? It might be ~50% blue and ~50% yellow (with a small probability that the machine explodes or the boxes change colour or whatever).
In fact, ‘you’ experience both. But no single instance of you remembers landing in both a blue box and a yellow box. Instead, one instance of you remembers landing in a blue box, and the other remembers landing in a yellow box. Both of you remember a single continuous narrative thread, from entering the in slot, to landing in a coloured box.
There is no sense in which the you from before the experiment landed in one box but not the other and could have predicted which one with better information. Each instance of you might initially think, “Well, I remember falling into the in slot, and then I ended up here. So the other guy must be the copy”. But this is false. There was one of you, and now there are two.
Similarly with quantum events. The universe bifurcates (trifurcates, whatever—this is obviously a simplification) and different instances of us experience each different possibility. Before a quantum experiment, it is nonsensical to try to make definitive predictions about “which” outcome we will experience. The feeling that this could/should be possible is an intuition based in the fact that we only see our own narrative thread running back into the past, we don’t see all the other narrative threads of the different versions of us. Different instances of us will experience each outcome of the experiment.
After the experiment, we can ask “which instance are we?” But before the experiment, it is meaningless to ask “which instance will we be?”
Here is my understanding (which I hope others will correct if it is mistaken).
Suppose I have a duplication machine, with an in slot and two out slots. You drop something in the in slot and two identical versions of it are produced in the out slots. They are down-to-the-atom identical at the moment of production—there is not an ‘original’ and a ‘copy’, there are ‘two originals’.
Now I position the machine so that one out slot drops into a blue box and the other into a yellow box. I drop you into the machine. As you tumble down the in slot, what is your subjective expectation about what colour box you will end up in? It might be ~50% blue and ~50% yellow (with a small probability that the machine explodes or the boxes change colour or whatever).
In fact, ‘you’ experience both. But no single instance of you remembers landing in both a blue box and a yellow box. Instead, one instance of you remembers landing in a blue box, and the other remembers landing in a yellow box. Both of you remember a single continuous narrative thread, from entering the in slot, to landing in a coloured box.
There is no sense in which the you from before the experiment landed in one box but not the other and could have predicted which one with better information. Each instance of you might initially think, “Well, I remember falling into the in slot, and then I ended up here. So the other guy must be the copy”. But this is false. There was one of you, and now there are two.
Similarly with quantum events. The universe bifurcates (trifurcates, whatever—this is obviously a simplification) and different instances of us experience each different possibility. Before a quantum experiment, it is nonsensical to try to make definitive predictions about “which” outcome we will experience. The feeling that this could/should be possible is an intuition based in the fact that we only see our own narrative thread running back into the past, we don’t see all the other narrative threads of the different versions of us. Different instances of us will experience each outcome of the experiment.
After the experiment, we can ask “which instance are we?” But before the experiment, it is meaningless to ask “which instance will we be?”