On 8/4/2011 2:59 PM, David Nyman wrote:
On 4 August 2011 18:44, meekerdb<meeke...@verizon.net>  wrote:

I don't see how life (including us) could exist except at a quasi-classical
level.  Evolution needs reliable replication to work with.  Given that we
evolved as quasi-classical beings, it follows that our perception,
psychology, and interaction with the world must be quasi-classical.
Neither do I.  Indeed, the lecturer was insistent on the lack of
"objective" criteria on the basis of which decoherent "worlds" must
obviously differentiate to yield the looked-for quasi-classical
environments.  Rather - as your comment implies - he spoke of the
process as inescapably "top-down" and "emergent", in the course of
which "we see what works" and "we spot (patterns)", etc.  IOW it seems
that the prior emergence of a point-of-view and its corresponding
"environment" are prerequisites for what is by then a
quasi-classically-informed functional or structural analysis of the
(conjecturally) basic micro-physical situation.  That is to say, the
role of the "observer" continues to be indispensable to the decoherent
account.

David

Hi David,

Does the lack of a clear definition of exactly what an observer is (that has the 'point of view' in the first place) not bother you? Additionally, the decoherence model, as I have studied of it so far, takes an 'all or nothing' assumption about entanglement. Why not consider the possibility that some degrees of freedom of the phase entanglement be preserved for longer periods than others. For example, consider a QM system with many observables associated with it - not just one particle with one set of possible positions, momenta, spin directions, etc. but many 'particles' each with their own spectra of conjugate observables. Does it not make sense that some 'parts' of the system would couple to the environment and decohere at one rate with others might decohere more slowly and others more quickly?

I have seen some papers that discussed this possibility, but I can't find their references at the moment.

Onward!

Stephen


On 8/4/2011 9:41 AM, David Nyman wrote:
Hi Stephen

Thanks for the link - very enjoyable talk.  As far as I could follow
it, he seemed to be saying that the differentiation of decoherent
"worlds" is in the final analysis a "psychological" matter - i.e. that
quasi-classical "reality", as ordinarily experienced, is consequent on
the selection of particular "best-fit" or "most fruitful"
interpretations of functional or structural features of the underlying
micro-physical state-of-affairs.
I don't see how life (including us) could exist except at a quasi-classical
level.  Evolution needs reliable replication to work with.  Given that we
evolved as quasi-classical beings, it follows that our perception,
psychology, and interaction with the world must be quasi-classical.

Brent

Whereas I did take to heart his
admonitions as to the differing explanatory priorities of physics and
philosophy, and particularly the centrality of functional explanations
to science in general, I was a bit troubled by the seeming assumption
that the requirement for such interpretation and selection just
"bottoms out", as it were, at the level of micro-physics (although he
did speculate at one point on the subject of "deeper" ontological
bases below this "substitution level").  I couldn't quite decide
whether he was actually "sweeping the 1st-person under the rug", in
Bruno's terms.  He didn't address this aspect directly, but perhaps
this signals an implicit belief that micro-physical-functional, or
ontological/epistemological, elements must always play a dual role in
any intelligible account of our situation.

I wonder what you thought.

David

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