On Mon, Nov 18, 2024 at 10:35 AM Russell Standish <[email protected]> wrote:
> On Mon, Nov 18, 2024 at 10:05:56AM +1100, Bruce Kellett wrote: > > On Mon, Nov 18, 2024 at 9:30 AM Russell Standish <[email protected]> > wrote: > > > > On Sat, Nov 16, 2024 at 03:52:25PM +1100, Bruce Kellett wrote: > > > > > > On Sat, Nov 16, 2024 at 3:28 PM Russell Standish < > [email protected]> > > wrote: > > > > > > On Sat, Nov 16, 2024 at 03:08:03PM +1100, Bruce Kellett wrote: > > > > On Sat, Nov 16, 2024 at 2:41 PM Russell Standish < > > [email protected] wrote: > > > > > > > > I don't think it requires this assumption. In fact > "physically > > real" > > > > is a rather nebulous concept anyway. > > > > > > > > > > > > If you want the 'other worlds' to be physically real, then > the original wave > > > > function must be physically real. > > > > > > That's a non-sequitur. The 'other worlds' are as real as this > one. The > > > reality of the wave function doesn't enter into it. > > > > > > > > > It does if the wave function is purely epistemic. In other words, > if it is > > > merely a means of calculating probabilities, then the supposed > 'other worlds' > > > do not exist. The probabilities are the probability that one, and > only one, > > > outcome is realized for each experiment. > > > > You've lost me here. Even if the wf is epistemic, it has no bearing > on > > whether other branches are as real as this one or not. > > > > > > It does have a significant bearing on the reality of the other branches. > One of > > the frequently stated arguments for many worlds is that it avoids the > problem > > of the wave function collapse. The collapse of the wave function is only > a > > problem if the wave function is a physical object, because then you run > into > > problems with instantaneous action at a distance or FTL physical action. > If the > > wave function is purely epistemic, namely, nothing more than a summary > of our > > knowledge about the physical system, there is no problem with collapse, > because > > the result of an experiment merely updates our knowledge, and the wave > function > > is updated to reflect this change in knowledge. This is exactly what > happens in > > classical probability. > > > > If the wave function is purely epistemic, there is no problem with > collapse, > > and the additional worlds that MWI introduces play no useful role and can > > readily be discarded. The other worlds need be real only if the wave > function > > itself is real, and some way of avoiding a physical collapse is > required. Once > > you avoid the collapse problem, the many-worlds scenario becomes otiose. > > I do agree with you that an epistemic wave function has no problem > with collapse, but I've always said the collapse issue was rather > secondary compared with the issue of what privileges one branch over > all the others as being "real". > Not a problem if the branches do not exist. All we have on the epistemic interpretation is the probabilities that the future will be one way or another. Stating that all branches are equally real with the one we observer > obviates the need for something to say one branch is more real than > the others, without committing to saying whether anything is real, or > even what "real" really means. > But there are no branches to be "equally real". You are fond of calling sound arguments "non sequitur". Your claim that all branches are equally real is indeed a *non sequitur*, in that it does not follow from anything at all. In contrast to your last statement, I find "single world > interpretations" otiose, in much the same way as I find Christian > theology otiose. > That is among the sillier remarks that you have made. Bruce > > > If you insist that you can have a purely epistemic wave function, and > also have > > all the other branches being as real as this one, then there is no > knock-down > > argument against your position. But such a position is clearly > contrived, and > > otiose, having no basis in quantum theory. > > > > The latter sentence is a non-sequitur. See above. > > > 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 visit https://groups.google.com/d/msgid/everything-list/CAFxXSLQsqThOnyEMYVK2voDRypk7kUM%2B1s9C0MxvY_uxboH3AQ%40mail.gmail.com.
