>>13268564Maybe my wording was poor, but if we start with knowing that CPTP maps are what quantum operations really are, then restricting to just unitary maps is what I meant by going "too far" ("too far" to be hyperminimalist, perhaps?).
>>13268572Yeah, but what are those extra degrees of freedom required to purify the system? It doesn't make any sense to add extra dimensions, especially when the claim is that the whole Universe is just the Hilbert space, full stop. Furthermore Stinespring dilation into a larger Hilbert space is nonunique, an artifact of the fact that it's really just a mathematical technique that doesn't necessarily have a physical meaning.
>>13268687I know this is obvious baiting from a midwit, but I'd like to point out that I my ultimate belief about "interpretations of quantum mechanics" is that it's all bunk anyway. QM is a model of reality. QFT is a model of reality. String theory, or whatever the ultimate unification of the Standard Model with gravity is, will just be a model. Science is just the human endeavor of modeling and predicting natural phenomenon. Asking whether the Universe really *is* a positive, trace-1 operator on a Hilbert space is a meaningless question, imo. These are merely mathematical objects, which have served remarkably well in this endeavor of science Perhaps they really are in one-to-one correspondence with Nature, who knows? But Nature isn't the mathematical object itself, it's just described or represented by it.
The map is not the territory.
