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apeiron
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#58
Dec28-10, 07:46 PM
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Quote Quote by yoda jedi View Post
and physical !
i posted it at the post #53
Yes, that Busch/Jaeger paper is an extremely valuable contribution here. Thanks yoda....
http://arxiv.org/PS_cache/arxiv/pdf/...005.0604v2.pdf

Zeilinger's take on the metaphysics is also worth reading (as no one can complain about his empirical credentials )...
http://www.quantum.at/fileadmin/zeilinger/philosoph.pdf

Anyway, from Busch/Jaeger is this elegant statement of the need for bold new metaphysics (and not to allow the "shut up and calculate" old guard shout us down)....

These quotations capture the tension between two opposing philosophical positions:
scientific realism versus instrumentalist empiricism. On the one hand, Einstein’s concern
was to uphold a world view based on what is commonly referred to as “local realism,”
in which probability plays a primarily epistemic role, whereas Heisenberg was prepared
to accept quantum indeterminacy and probability as primarily ontic, that is, as essential
features of the physical world. On the other hand, there is still a strong presence of the
view that Quantum Mechanics is nothing more than a formalism for the calculation of
measurement statistics.
Many physicists now adopt a pragmatic double approach: they practice a realist outlook
for the purposes of heuristic explorations of new models and the discussion of experiments, using intuitive pictures of individual (sub)atomic objects; but when challenged, they only admit to the minimal probabilistic or statistical interpretation of QuantumMechanics. This conflicted attitude has similarly been noted by D’Espagnat [4].
It seems to us that a more coherent and productive approachwould be to investigate systematically all possible variants of realist interpretations of Quantum Mechanics, including those in which probabilities are not essentially epistemic.
Zeilinger is not nearly so specific about the proper focus of this next step, but he endorses a holistic approach in general....

It is very highly likely that the new paradigm will contain holistic aspects. This follows in the most direct way from the fact, that in the Copenhagen interpretation it is impossible to dissect a quantum phenomenon into its parts. This may be expressed by saying that the preparation of a quantum system, its evolution and its observation, form one whole entity which, following both Bohr and Wheeler, we call the quantum phenomenon. Holistic aspects also follow from the fact that in a multi-particle-system it is not possible, not even for perfect correlations, to pre-assign properties to the individual members of the ensembles[35]. Such properties can only be assigned in the specific context of the whole experimental setup for all particles together. Then, in any case, they show up only in the correlations. This, I suggest, is another beautiful corroboration of Bohr's point of view[36].
In this statement further on in Busch/Jaeger, they get precisely to the heart of the problem as I have frequently outlined it.....

In the case of quantum systems, properties can be considered objectively indefinite and sets of propositions regarding them complementary to specific other sets of propositions, so that it becomes impossible to jointly attribute them. Thus, quantum mechanics involves a unique form of vagueness distinct from those considered before.
What is crucial here is that complementarity (asymmetry, dichotomy) is part of the QM package. The logic involves both the initiating conditions, the indeterminate potential that is vague, and then also the decohering observation, the global set of constraints that crisply dichotomises this potential.

This is what is missing from most ontic vagueness proposals. People say well a vagueness is free do develop in any fashion really. But no. Only dichotomous outcomes are in fact possible. This was Anaximander's insight 2400 years ago. It has echoed down the years in the I Ching, Hegelian logic, etc. Yet people still seem to manage to overlook it.

There is just no accident that QM is based on orthogonal or complementary crisp observables. Systems logic says it could be no other way!

Here Busch/Jaeger state a consequence of this view. We can then go on to define vagueness (empirically, physically!) in complementary terms. It is a mixed state - a mixture of paired, dichotomous, outcomes.

It is also appropriate to think of an indeterminate property as an element of unsharp reality in the following sense. If a property P is indeterminate, then so is its complement P⊥ = I −P. Thus, both P and P⊥ have a nonzero degree of reality, they coexist, to a nonzero degree of actuality, in the given state. In this sense they are both simultaneously but “unsharply” defined. This description seems to be in agreement with Bohr’s account of the uncertainty relation: in a quantum state given by (say) a Gaussian wave function, the position and momentum of the quanton are, according to Bohr, both defined with a latitude. Bohr uses the phrase “unsharply defined individual” to characterize this situation.
Busch/Jaeger keep on hitting the mark. They correctly get the distinction between vagueness and fuzzy logic approaches...

It is important to note that the nature of the fuzziness of quantum effects differs fundamentally from that of fuzzy sets, however. In the latter case, the rule for the application of one of a set of alternative fuzzy sets is based on there being an underlying fine-grained level of actual reality.
So as I replied to the OP, between total realism and total unrealism, there is the intermediate ontic position which takes indeterminacy seriously.

And Busch and Jaeger is probably the best paper I've seen on this so far.