On Tue, May 30, 2017 at 1:55 PM, Bruce Kellett <bhkell...@optusnet.com.au> wrote: > On 30/05/2017 7:28 pm, Telmo Menezes wrote: >> >> On Tue, May 30, 2017 at 3:47 AM, Pierz <pier...@gmail.com> wrote: >>> >>> So you are talking different >>> languages. >> >> Not sure I agree. We are perhaps implicitly assuming different theories of >> mind. >> >>> I don't know if Telmo is aware or not of the conventional view of >>> decoherence - that it is a matter of the spread of information into the >>> environment by means of physical interactions between particles. Telmo's >>> musings about the effect of destroying memory (could it change the >>> measure >>> of different futures?) clearly expresses this subjectivist view. >> >> I get your point with decoherence. >> Again, I would say that it all depends on theories of mind. What does >> mind supervene on? Perhaps it is true that every single coupling with >> the environment prevents the current observer state to become >> compatible with other branches. But can we be sure? I feel that such >> certainties come from a strong belief in emergentism (which I cannot >> disprove, but find problematic). >> >>> FWIW, you >>> are expressing my own understanding of the situation: there can be no >>> superposition of red and green screens or dinosaurs, or dead and live >>> cats, >>> because there can be no quantum superposition of macroscopic objects. >>> Superpositions of wave functions are only possible for systems isolated >>> from >>> interaction with their environment, which is why quantum computers are so >>> fricking hard to make: keeping aggregates of particles isolated from >>> interactions with the surrounding environment is exponentially more >>> difficult as the system grows in size. >> >> The main question for me is this: can two branches hold different >> observer states, if they differ only by things that are not >> observable? > > > Yes, but I think we should be talking about quantum mechanics here, and that > is a well-defined physical theory that is not really concerned with any > theory of mind.
Ok. > There have been some interpretations of quantum mechanics > that ascribe the mind a role in the collapse of the wave function, or some > such; and some who re-interpret the many worlds idea as a 'many minds' > picture; but these issues do not seem to be relevant to any discussion of > the quantum formalism itself. > > In the discussions on this list, it seems that MWI is the dominant > understanding of QM. That is fine, one can certainly talk about things in > this way. But it should be borne in mind that MWI is actually equivalent to > the less well known decoherent histories approach. I guess that in my > comments earlier in this thread, I was emphasizing the decoherent histories > understanding. In many worlds, worlds separate off when irreversible > interactions with the environment zero out the interference terms between > different elements in the superposition. This happens inevitably all the > time, and measurements, or observers, play no essential role in the process. > Each world of the MWI is thus produced by the process of decoherence acting > on the initial quantum state. Each decoherent line then evolves on to > produce its own set of future decoherent lines. Following through any > particular line gives a decoherent history -- one for each world of the MWI. > > Since the processes of decoherence and the formation of histories or worlds > are independent of the observer and of the mind, it is clearly possible that > different branches (or histories) can differ only by things that are not > observed, or even not observable. And this is just a matter of the formalism > of quantum mechanics -- it has nothing to do with any theory of mind. The > only thing that I would say, though, is that your theory of mind, and your > theory of the origin of physics, must be compatible with this understanding > of quantum mechanics -- or else your theory of mind/physics is falsified. > > > 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 everything-list+unsubscr...@googlegroups.com. > To post to this group, send email to everything-list@googlegroups.com. > Visit this group at https://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. -- 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
