Many worlds interpretation of QM is that everything continues evolving unitarily, even you when you hear about the result. It's just that "being in a superposition" doesn't feel like listening to the garbled sound of someone simultaneously telling you that the result was positive and that it was negative, or looking at a blurry instrument screen reporting two results at once. Each component of you in the superposition feels like it got a single clear definitive measurement result. It feels the same as not being in a superposition.
It appears as if one of the main reasons for almost a-priori rejection of the Many Worlds interpretation lies in the words "many worlds". More often this metaphor gets in the way instead of helping. It seems as if you have to accept something "more", yet, at its core, the Everettian interpretation is the simplest pure consequence of QM. We just have to grapple with the psychological consequences if being a cog in the machine and we devise further metaphors to help us talk about how it would "feel" to be in superposition.
Is there a better way to build intuitions how an information processing system would behave while being in superposition?
Things get complicated when we throw humans in the mix, perception and consciousness and all. But modelling even simpler machines and their "point of view" can be insightful.
In this day and age it shouldn't be hard to imagine the working of a computer that uses computer vision algorithms to perceive its world and take action as a result, acting as a "causality amplifier". For example image we feed it the output of some QM experiment and instruct it output a description of what it "sees" (as we routinely do with cat pictures classification).
I assume it would be far less controversial to think about the unitary evolution of the wave function if the system being described is a QM experiment plus a computer rather than the same QM experiment and a human.
Yet, there are many similarities. The output of this computer (the classification) would be in superposition, and when measured by us it would appear as if the wave function collapsed. But we could add another such computer in the mix and ask ourselves "does it also see the wave function collapsing"? Well can program it to take the measurement and record the answer and then convey the answer to us (or to another computer down the chain). These "answers" are the "point of view" of the computer. It will "observe" decoherence yet it won't be decohered itself, as its own statement about whether it observed decoherence is itself in superposition and thus can be used as a further input to other machines witnessing subjective decoherence.
> It's just that "being in a superposition" doesn't feel like listening to the garbled sound of someone simultaneously telling you that the result was positive and that it was negative, or looking at a blurry instrument screen reporting two results at once.
It seems like there's regularly articles saying stuff like "QM implies that both outcomes happen, but it's a longstanding mystery why we only see one outcome", as if they seriously expect your hypothetical to be the consequence of QM. I'm so frustrated at that, because as you say, seeing one outcome is exactly what you'd expect to see from inside of a superposition.
It's almost as frustrating to see as it would be to see an article saying "Newton's theory of gravity says mass attracts mass, but it's a longstanding mystery why we haven't all fallen into the sun". The theory already has an answer for that if you follow the chain of consequences from it.
