On Thursday, May 24, 2018 at 7:33:06 PM UTC, Brent wrote: > > > > On 5/23/2018 11:48 PM, agrays...@gmail.com <javascript:> wrote: > > > > On Thursday, May 24, 2018 at 6:02:30 AM UTC, Brent wrote: >> >> >> >> On 5/23/2018 10:37 PM, agrays...@gmail.com wrote: >> >> >> >> On Thursday, May 24, 2018 at 4:53:29 AM UTC, Brent wrote: >>> >>> >>> >>> On 5/23/2018 9:43 PM, agrays...@gmail.com wrote: >>> >>> >>> >>> On Thursday, May 24, 2018 at 4:28:58 AM UTC, Brent wrote: >>>> >>>> >>>> >>>> On 5/23/2018 9:17 PM, agrays...@gmail.com wrote: >>>> >>>> In the MWI interpretation there is no reason to preference one over the >>>>> other with the honorific of "exists". They are just projective subspaces >>>>> that are essentially (FAPP) orthogonal to one another. >>>>> >>>> >>>> I can buy that, although tentatively, with difficulty, until I see the >>>> mathematics which demonstrates it. AG >>>> >>>> >>>>> Each one includes copies of the system, the environment, and the >>>>> observer(s) which is necessary so that it constitute a classical "world" >>>>> in >>>>> which everyone agrees on the result. >>>>> >>>> >>>> This I absolutely CANNOT buy, as I have explained numerous times. >>>> Cannot decoherence and the MWI have descriptive value without all of this >>>> COPYING being assumed, which I find outlandish? Would it be fatal to any >>>> of >>>> these concepts to affirm that the entanglements which occur in these >>>> subspaces are equivalent to measurements in these subspaces? AG >>>> >>>>> >>>> It's fine if you just assume the other subspaces vanish as far as doing >>>> physics. Metaphysically it's problematic because you've used a certain >>>> theory up to that point which predicts that all the subspaces are equally >>>> real (and may be more probable than the one you experience) and there are >>>> copies of you and your lab etc which are equally real and now you're going >>>> to stop using that theory which was so amazingly successful...why? >>>> >>>> Brent >>>> >>> >>> The other subspaces don't vanish. They continue to exist and all >>> possible measurements are in fact measured according to my proposal. But >>> the subspace in which the observer exists seems apriori different and more >>> significant in terms of physical reality; it's the environment in which all >>> entanglements of all subspaces come into being. >>> >>> >>> The entanglements coming into being is what makes the subspaces become >>> orthogonal and become separate "worlds". The entanglements are different >>> (in detail) in each different subspace reflecting the fact that they are >>> correlated with a different result. >>> >> >> Yes, I am imagining a different result in each subspace. AG >> >>> >>> It seems metaphysically problematic to give all subspaces the same >>> existential status, when only one provides the environment for all >>> entanglements for all subspaces. AG >>> >>> >>> I don't know what entanglements you're talking about. The system >>> measured has different entanglements with the different environments and >>> observers in the different "worlds". There is no privileged world which >>> provides a privileged environment and observer. >>> >> >> I am imagining a superposition of states, and when the measurement >> occurs, each component of the superposition becomes entangled with the >> environment in this world, the world in which the measuring device exists. >> Then, somehow, the subspaces become orthogonal FAPP. AG >> >> >> No, it's the interaction, the entangling of different results with the >> environment, that makes the subspaces orthogonal. >> > > That's what I assumed; that the entanglement for each subspace causes the > orthogonality (though I can't imagine how that would come about). > > > If you look at the mathematics of the total (system+environment+observer) > density matrix, the off-diagonal terms have products of wf terms from the > system and environment. The environment wf are of course unknown, so one > averages over them by taking the trace over them. This makes the cross > terms for the reduce density matrix (that of the system) go to zero, so now > it is *formally* the same as the probability matrix for a set of > classical states. As Bruce points out this "taking the trace" is a > non-unitary operation that is equivalent to applying a projection operator, > as in the Copenhagen interpretation. Which is why I say decoherence only > gets you part way to solving the measurement problem. It has a mechanism > and a statistical rationale, but it still takes a little jump to get to the > classical definite result. > > Isn't "the environment" the this-world environment, the measuring device > in this world? Isn't it this entanglement that destroys the interference > FAPP with the other components of the superposition in this world, which > might be what the Bucky Ball experiment establishes? What are you objecting > to? AG > > > That there is a unique "this world". I use use "world" (with the scare > quotes) to indicate a coherent, quasi-classical world where observers don't > see superpositions of alive and dead cats. The measuring device and the > environment is in all the "worlds", one for each measurement result. > > I happened across a very good book that discusses these questions well > without mathematics, "Mind, Brain, and the Quantum" by Michael Lockwood. > It's a philosophy book about epistemology and consciousness and discusses a > lot more about the brain and it's function. But is has a couple of chapters > on the quantum measurement problem. It says the same thing Bruce and I > have been saying except Lockwood looks at what I've been calling "worlds" > (per the usual MWI terminology) as macroscopic states which exist in > superposition in one world (which is usually called the universe or > multi-verse), the superpositions just happen to be orthogonal (FAPP) and so > don't interfere. > > Brent > > > The result is in effect encoded all through the subspace, that's why >> different people in that "world" can agree on what happened; that's what >> makes it a (quasi) classical world where people don't see superpositions of >> measurement results. >> >> Brent >> > Would it be consistent with decoherence theory to say that each component of a superposition gets entangled with the environment defined by the lab / instrument in which an experiment is performed -- what I have been calling "this world" -- and the other branches, one for each of the remaining eigenstates -- are mutually orthogonal, and orthogonal to the subspace in "this world"? I am positing a model wherein every outcome is realized, but only one outcome is associated with the lab / instrument; the other outcomes or measurements occur without needing a measuring device -- like those Bucky Balls didn't need to be measured by any device to lose their interference. AG
-- 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.
