On 18 Sep, 22:20, "Stephen P. King" <stephe...@charter.net> wrote:
> Hi Peter and Friends,
> -----Original Message-----
> From: everything-list@googlegroups.com
> [mailto:everything-l...@googlegroups.com] On Behalf Of 1Z
> Sent: Friday, September 17, 2010 8:16 AM
> To: Everything List
> Subject: Re: A superposition in QM is just due to a choice of basis?
> On 28 Aug, 20:29, "Stephen P. King" <stephe...@charter.net> wrote:
> > Hi Bret,
> >             Could you elaborate on this point and/or point me to a
> > good discussion of it? From what I have studied so far there is no
> > solution to the measurement problem so far in terms of an explanation
> > of the way that the choice is made in each successive event, world or
> > whatever. Even decoherence does not help things from what I can tell,
> > but this business that "What's a superposition in one basis is still
> > an eigenfunction in some basis." is new to me.
> It is a much overlooked point. It pretty completely disposes of the version
> of MWI that says the objectively decomposes into N classical universes.
> I believe the relativity of superposition is best handled by the relational
> interpretation
> http://en.wikipedia.org/wiki/Relational_quantum_mechanics
> ***
>         I would like to quote from this web article reference by 1Z  and
> make a comment:
> "Observer-dependence of state
> According to O, at t2, the system S is in a determinate state, namely spin
> up. And, if quantum mechanics is complete, then so is his description. But,
> for O', S is not uniquely determinate, but is rather entangled with the
> state of O — note that his description of the situation at t2 is not
> factorisable no matter what basis chosen. But, if quantum mechanics is
> complete, then the description that O' gives is also complete.
> Thus the standard mathematical formulation of quantum mechanics allows
> different observers to give different accounts of the same sequence of
> events. There are many ways to overcome this perceived difficulty. It could
> be described as an epistemic limitation — observers with a full knowledge of
> the system, we might say, could give a complete and equivalent description
> of the state of affairs, but that obtaining this knowledge is impossible in
> practice. But whom? What makes O's description better than that of O', or
> vice versa? Alternatively, we could claim that quantum mechanics is not a
> complete theory, and that by adding more structure we could arrive at a
> universal description — the much vilified, and some would even say
> discredited, hidden variables approach. Yet another option is to give a
> preferred status to a particular observer or type of observer, and assign
> the epithet of correctness to their description alone. This has the
> disadvantage of being ad hoc, since there are no clearly defined or
> physically intuitive criteria by which this super-observer ("who can observe
> all possible sets of observations by all observers over the entire
> universe"[8]) ought to be chosen.
> RQM, however, takes the point illustrated by this problem at face value.
> Instead of trying to modify quantum mechanics to make it fit with prior
> assumptions that we might have about the world, Rovelli says that we should
> modify our view of the world to conform to what amounts to our best physical
> theory of motion.[9] Just as forsaking the notion of absolute simultaneity
> helped clear up the problems associated with the interpretation of the
> Lorentz transformations, so many of the conundra associated with quantum
> mechanics dissolve, provided that the state of a system is assumed to be
> observer-dependent — like simultaneity in Special Relativity. This insight
> follows logically from the two main hypotheses which inform this
> interpretation:
> Hypothesis 1: the equivalence of systems. There is no a priori distinction
> that should be drawn between quantum and macroscopic systems. All systems
> are, fundamentally, quantum systems.
> Hypothesis 2: the completeness of quantum mechanics. There are no hidden
> variables or other factors which may be appropriately added to quantum
> mechanics, in light of current experimental evidence.
> Thus, if a state is to be observer-dependent, then a description of a system
> would follow the form "system S is in state x with reference to observer O"
> or similar constructions, much like in relativity theory. In RQM it is
> meaningless to refer to the absolute, observer-independent state of any
> system."
>         It is this notion that "it is meaningless to refer to the absolute,
> observer independent state of any system" what has deep implications when
> applied to the Universe itself. In effect, it argues that there is no such
> thing as a "view from nowhere" ala Nagle IF and only IF we are thinking that
> that a state can have any sort of property definiteness associated to it as
> an independent entity. This seems to undermine the traditional idea of an
> objective universe existing with a definite set of properties

without supporting the traditional alternative that it is all in the

> absent the
> notion of interactions of systems with each other. OTOH, we could take this
> as a positive and propose that definiteness emerges from interactions
> between subsets of the Universe.

definiteness as far as they are concerned

> This is where I believe the notion that
> there is a plurality of Minds obtains in a coherent fashion.
>         On this list we have been discussing any ideas that run from
> metaphysical postulates, such as Arithmetic realism, etc.  We need to be
> sure that our thinking is consistent with the implications of ideas such as
> this one discussed here. The line of questions that I have been making
> relates to whether or not it is consistent to consider the notion of
> interaction without some explanation or allowance for a notion of change as
> a fundamental primitive.
>         I have tried to argue, with very limited success, that we need to
> rethink the idea that we can have entities, such as numbers or strings of
> integers, that can have particular properties and be differentiated with
> respect to each other and completely neglect how this is the case.
> Basically, this point that Carlo Rovelli is trying to make argues against
> Platonism in the sense that the Ideals cannot be considered to have
> properties that obtain from their mere existence. We cannot just do a Box
> Diamond p statement and establish that p exists with some set of properties
> and not some complementary set of properties. We need to be more specific;
> that Box Diamond p specifies some predicate only has some sort of
> definiteness if and only if there is some sort of specified of that
> sentence.
> Onward!
> Stephen P. King

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