On Friday, February 7, 2020 at 7:10:54 PM UTC-6, Bruce wrote: > > On Sat, Feb 8, 2020 at 11:51 AM Lawrence Crowell <[email protected] > <javascript:>> wrote: > >> On Friday, February 7, 2020 at 6:16:45 PM UTC-6, Bruce wrote: >>> >>> On Sat, Feb 8, 2020 at 4:33 AM Stathis Papaioannou <[email protected]> >>> wrote: >>> >>>> On Fri, 7 Feb 2020 at 15:59, Bruce Kellett <[email protected]> >>>> wrote: >>>> >>>>> >>>>> This argument from Kent completely destroys Everett's attempt to >>>>> derive the Born rule from his many-worlds approach to quantum mechanics. >>>>> In >>>>> fact, it totally undermines most attempts to derive the Born rule from >>>>> any >>>>> branching theory, and undermines attempts to justify ignoring branches on >>>>> which the Born rule weights are disconfirmed. In the many-worlds case, >>>>> recall, all observers are aware that other observers with other data must >>>>> exist, but each is led to construct a spurious measure of importance that >>>>> favours their own observations against the others', and this leads to an >>>>> obvious absurdity. In the one-world case, observers treat what actually >>>>> happened as important, and ignore what didn't happen: this doesn't lead >>>>> to >>>>> the same difficulty. >>>>> >>>> >> Carroll and Sebens worked a paper a year ago illustrating how MWI was >> consistent with Born rule. They did have to restrict paths or states that >> were too far removed from being a good Bayeisan prior, so it is a bit >> loose. However, it was not bad. >> > > Not bad!!!! I suppose if you feel justified in just throwing away anything > that does not suit your favourite theory, then you can get away with > anything. It is the fact that these 'worlds' that are far removed from > what one wants to see cannot just be "thrown away" that destroys MWI. Given > that the probability of particular outcomes no longer has meaning when all > outcomes necessarily occur, one cannot use any observed data to justify any > theory about the probabilities. All theories are just as good, or just as > bad. Consequently, assuming probabilities for particular outcomes no longer > makes any sense. > > The set of amplitudes or paths thrown away is a small measure. The bounds are not entirely certain, but they are comparatively small.
> > The inability to define a clear probability to a particular world path is >> argued to be one reason that MWI is the best interpretation to work quantum >> gravitation. This is a sort of nonlocality. I am not sure this clinches MWI >> as the clearly superior interpretation. Much the same nonlocality can be >> identified with quantum spacetime if it is built up from quantum >> entanglements, thus avoiding the use of an interpretation. >> > > I doubt that anything along these lines is going to resolve the basic > problem. > > MWI is sworn by a number of physicists, though Copenhagen still holds it >> own and Qubism is growing adherents. Qubism actually also has a few things >> going for it. I frankly see all of these as ancillary postulates that have >> limited usefulness and mostly useful in expositories. >> > > Perhaps some interpretations make more sense than others. It seems, from > the considerations that I have raised, that, despite what many physicists > say about MWI, it is a failure as an interpretation of QM -- it does not > allow one to use experimental data to evaluate the theory one way or the > other. As Kent says, "Everettian quantum theory is essentially useless, as > a scientific theory, unless it can explain the data that confirms the > validity of standard quantum mechanics." And Everett cannot do this. > > Bruce > The operative word is theory, and I do not see quantum interpretations as theories. They are more in a sense metaphysics used to provide some explanatory means to makes QM more understandable to our classical brains. LC -- 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/e47cec7d-0516-40c1-9677-714039c5d798%40googlegroups.com.
