On Mon, Aug 12, 2019 at 7:30 PM Bruno Marchal <[email protected]> wrote:
> On 11 Aug 2019, at 14:09, Bruce Kellett <[email protected]> wrote: > > It is not a matter of the difference between collapse or no-collapse > models -- it is a matter of the basic interpretation of what Everett's > "relative states" actually are, and why the basis problem is so important > for Everett. > > > Everett makes clear that the choice of the base os irrelevant for the > global description, > Maybe for the global description, but not for recovering the results of experience. Everett got this latter problem wrong (he probably wasn't even aware that there was a problem.). Zurek says: "The basis ambiguity is not limited to pointers of measuring devices. One can show that also very large systems (such as satellites or planets) can evolve into very non-classical superpositions. In reality, this does not seem to happen. So there is something that picks out certain preferred quantum states, and makes them effectively classical. Before there is collapse, a set of preferred states, one of which is selected by the collapse must somehow be chosen. There is nothing in the writings of Everett that would hint at such a criterion for such preferred states, and nothing to hint that he was aware of this question........ The preferred basis problem was settled by environment induced superselection (einselection), usually discussed along with decoherence. When environmental monitoring is focussed on a specific observable of the system, its eigenstates form a pointer basis: They entangle least with the environment (and, therefore, are least perturbed by it.) This resolves the basic ambiguity." (Zurek, arxiv:0707.2832 July 2007) Zurek goes on to develop this at some length, but the basic point is stability under environmental interactions, so the permanent, objective records of the result can be formed in the environment. This is the basis of intersubjective agreement about the result, namely, objectivity. Quantum Darwinism means that the results that we observe are classically stable. and the choice of the base is done by the observer for the local > description, > The observer does not chose the basis -- he might choose what to measure, but it is the environment that ultimately decides what bases is stable, and which other bases rapidly collapse on to states in the pointer basis. > exactly like with digital mechanism, where the notion of universal numbers > play the role of the base. The whole theology and physics does not depend > on the choice of the universal machinery we posit at the start, but from > the points if view of each relative universal numbers, such difference play > a key role in the local happenings and predictions. > This is no longer quantum mechanics, nor has it anything to do with physics. Bruce -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLS8%3DuFQx96qadn%3DQQcf32gn11%2BG1X6vC6xZA6cvNnd8AA%40mail.gmail.com.
