On Tue, May 30, 2017 at 1:55 PM, Bruce Kellett <[email protected]> wrote: > On 30/05/2017 7:28 pm, Telmo Menezes wrote: >> >> On Tue, May 30, 2017 at 3:47 AM, Pierz <[email protected]> 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 [email protected]. > To post to this group, send email to [email protected]. > 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
