>Whether the wavefunction collapses or not shouldn't depend on what we consider the system to be. It's not about consideration in terms of choice of what const

>Whether the wavefunction collapses or not shouldn't depend on what we consider the system to be. It's not about consideration in terms of choice of what constitutes a system; the systems are defined by sensitivity to informative states. It's like a quantum analog to the light cone, the information boundary defines the system. But this information boundary is much more elaborate and dependent on the dynamics of the structures involved. In this case, the mirror imparts a different information dynamic than the diode and so has different implications for the information boundaries. What the rules are that govern the interactions that integrate the informative states of two systems isn't obvious. Funnily enough, I've thought a lot about this problem in an entirely different context. Somewhat surprising that it comes up naturally in quantum mechanics. I don't have any fully worked out details, but I do have some intuition. The issue is related to supervenience of macro structures on micro details. The macro structures can carry information (i.e. have mutual information) about external systems; this is how two systems are informationally integrated. A measurement is when the macrostate of one system becomes correlated with the microstate of another system. The correlation is between macro and micro because for state to be useful requires it to interact in a specific way to result in a macrostructure correlation which can in principle be computed with. It's the information analog of free energy. Not all interactions produce state that one can compute with. Information integration requires precisely this kind of state. I suspect the exact nature of this kind of interaction can be characterized in principle. >What you apparently are inclined to deny is the notion that you could ever be put in a quantum superposition yourself, and that this would merely feel like observing one particular nondeterministic outcome out of a deterministic distribution of possible outcomes. Superpositions for thee, but not for me! I don't deny that I could, I just don't seem to be. And the interpretation that coheres with unobserved superposition I reject for external reasons. I don't have any qualms about the implications for personal identity from MWI (assuming that's what you're getting at).