> On 12 Aug 2019, at 14:28, Bruce Kellett <[email protected]> wrote: > > On Mon, Aug 12, 2019 at 7:30 PM Bruno Marchal <[email protected] > <mailto:[email protected]>> wrote: > On 11 Aug 2019, at 14:09, Bruce Kellett <[email protected] > <mailto:[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.).
That is not my feeling, but I will take a look back to what Everett said in his long text. > 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. I agree (with Zurek). > In reality, this does not seem to happen. OK. > So there is something that picks out certain preferred quantum states, and > makes them effectively classical. … relatively to the observer. The observer is itself the result of many interaction/measurement which picked the base defining its computational properties. > Before there is collapse, a set of preferred states, one of which is selected > by the collapse must somehow be chosen. OK, with “apparent collapse” instead of “collapse”. The context should be given if this is what Zurek means. Some texts by Zurek explicitly rejects the idea that the collapse is a physical event (like in Everett). > 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. OK. And this explains the appearance of quasi classical histories. > When environmental monitoring is focussed on a specific observable of the > system, its eigenstates form a pointer basis: Yes. This is how the “brain” has been able to evolve, and why the position observable plays a key role for macroscopic entities. > They entangle least with the environment (and, therefore, are least perturbed > by it.) This resolves the basic ambiguity." (Zurek, arxiv:0707.2832 July 2007) OK. > > 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, Yes, it provides a notion of first person plural sharable observation. > 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. OK. My way to express this was perhaps unclear. It is evolution which has “chosen” the base, somehow. > > 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. Only because you work in the materialist and non mechanist frame, I guess. With mechanism, those becomes key element in the explanation of why and how a physical reality appears and get sharable by many independent universal machines. Bruno > > 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] > <mailto:[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 > > <https://groups.google.com/d/msgid/everything-list/CAFxXSLS8%3DuFQx96qadn%3DQQcf32gn11%2BG1X6vC6xZA6cvNnd8AA%40mail.gmail.com?utm_medium=email&utm_source=footer>. -- 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/8F76FB60-DF64-49EE-A251-3534AF7AC980%40ulb.ac.be.
