On 8/4/2011 4:43 PM, Stephen P. King wrote:

Hi Brent,On 8/4/2011 4:38 PM, meekerdb wrote:On 8/4/2011 12:10 PM, Stephen P. King wrote:Hi Brent, On 8/4/2011 1:44 PM, meekerdb wrote: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.thatquasi-classical "reality", as ordinarily experienced, isconsequent onthe selection of particular "best-fit" or "most fruitful"interpretations of functional or structural features of theunderlyingmicro-physical state-of-affairs.I don't see how life (including us) could exist except at aquasi-classical level. Evolution needs reliable replication towork with. Given that we evolved as quasi-classical beings, itfollows that our perception, psychology, and interaction with theworld must be quasi-classical.BrentExactly what does the 'quasi-classical" property imply and whatdoes it bring to the table that is not in the quantum realm? Is itpersistence of structure? How does the unitary evolution of the wavefunction not provide that?It doesn't. Although decoherence theory is suggestive; it has notyet been able to uniquely define "quasi-classical" within theframework of QM without additional assumptions about pointer bases.Again, what is the motivation of the quasi-classical approach?More simple calculations? More intuitive models?

Predicting what is actually observed.

I am asking about the motivation to maintain a paradigm that has longlapsed into obsolescence! The universe is not a giant clock work ofisolatable and separable parts as the scientists of the 18th and 19thcentury believed. We have sufficient evidence to see this clearly, sowhy the romantic attachment with this vision?

Strawman. I carefully wrote *quasi-classicality*, not classicality.

The assumptions about pointer bases is a throwback to Copenhagen,where Borh, that great champion of QM desperately tried to get theemerging experimental evidence to get along with the classical vision.Few people still how up the Copenhagen interpretation as viable, withits strange duality of classical measuring devices interacting withquantum systems. Most people have adopted the Everetian vision of apurely quantum universe, and yet that pesky basis problem persists!What I am investigating is an attempt to solve that problem byconsidering how the interactions between many systems tends to induceglobal behaviors that are selective, selective in the same sense aswhat we need to solve the basis problem.

I hope you succeed. There have been

Consider what happens when a large number of people communicatewith each other. Even if they start off speaking their own uniquelanguage eventually, because of the way that communications in thereal world occurs, there will emerge a single language thatprodominates. In a similar way, I believe that a basis set emerges outof the interactions between a large number of QM systems, a basis thatrepresents the maximally consistent set of observables for thatcollection. This is a very crude sketch of the idea, but to explore itI must jettison all of the classical ideas that so far have beenpoisoning the well of thought on this problem.

`But if you succeed you must ultimately recover the classical appearance`

`of the world and the Born rule, at least as approximations.`

In fact, the quantum realm seems to even be over-determinative inthe sense that no only is one 'actual' real state of affairs of aworld non-contradictorily exists in the amplitudes of the wavefunction but all possible versions of it.A popular myth. QM does not provide that "everything happens". Forexample eigenstates of an operator remain eigenstates in the unitaryevolution.Popular and mythological to whom? How does the persistence ofeigenstates under unitary evolution contradict what I wrote? Is itincorrectly claimed that a quantum state is equivalent to *allpossible statements" that can be made of a system?While it is true that we seem to observe only one Boolean logicrepresentable slice of the totality of what is coded in theamplitudes, it can easily be shownIt isn't "shown" at all. It's hypothesized in one model.Which model and what are the alternatives?

`In Everett's interpretation. In, for example Asher Peres`

`interpretation, the wave function just encodes what we know about an`

`ensemble of state preparations.`

that this is just something like one subset of the set of all of theBoolean representable 'possible worlds' that we see coded in theamplitudes.I simply do not comprehend this emotional clinging to aclassical vision of the world; especially given the fact that it isdemonstrably false! It seems to me that your argumentation is justan attempt to preserve your apparent belief in naive realism.It seems to me that your reification of the wave function is an overreaching extension of what we know from our classical observationdriven by a distaste for randomness.Is it that I have a distaste for randomness or is it that you havean irrational affection for randomness? What does randomness give youthat you cannot live without?

`The Born rule and testable predictions. As Omnes says, "Quantum`

`mechanics is a probabilistic theory, so naturally it predicts`

`probabilities."`

`See for example: arXiv:0905.0624v2 , 0808.2415v1 , 0810.2657v1`

`and 0312058v3. Of course you may consider these physicists as mere`

`romantics emotionally attached to mathematical logic.`

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