On 9/26/2019 5:53 PM, Bruce Kellett wrote:
On Fri, Sep 27, 2019 at 10:35 AM 'Brent Meeker' via Everything List
<everything-list@googlegroups.com
<mailto:everything-list@googlegroups.com>> wrote:
On 9/26/2019 5:01 PM, Lawrence Crowell wrote:
On Wednesday, September 25, 2019 at 6:54:59 AM UTC-5, John Clark
wrote:
It seems that nearly everyone on the list has a strong
opinion about Sean Carroll's new book, but has anyone other
than me actually read it?
John K Clark
I have not read his book, but I have read his papers and the one
he coauthored with Sebbens. I know what he has done. I am
definitely agnostic about MWI as I am with all interpretations.
Carroll and Sebens has though opened the door to a relationship
between the Born rule and MWI,
Didn't you read /Quantum Theory of the Classical: Quantum Jumps,
Born’s Rule, and Objective Classical Reality via Quantum Darwinism
/by Zurek. arXiv:1807.02092v1 [quant-ph] 5 Jul 2018
He derives the Born rule from what he calls "environment induced
supersymmetry".
/Emergence of the classical world from the quantum substrate of
our Universe is a long-standing//
//conundrum. I describe three insights into the transition from
quantum to classical that are based//
//on the recognition of the role of the environment. I begin with
derivation of preferred sets of states//
//that help define what exists - our everyday classical reality.
They emerge as a result of breaking of//
//the unitary symmetry of the Hilbert space which happens when the
unitarity of quantum evolutions//
//encounters nonlinearities inherent in the process of
amplification – of replicating information. This//
//derivation is accomplished without the usual tools of
decoherence, and accounts for the appearance//
//of quantum jumps and emergence of preferred pointer states
consistent with those obtained via//
//environment-induced superselection, or einselection. Pointer
states obtained this way determine//
//what can happen – define events – without appealing to Born’s
rule for probabilities. Therefore, p k =//
//|ψ k | 2 can be now deduced from the entanglement-assisted
invariance, or envariance – a symmetry of//
//entangled quantum states. With probabilities at hand one also
gains new insights into foundations//
//of quantum statistical physics. Moreover, one can now analyze
information flows responsible for//
//decoherence. These information flows explain how perception of
objective classical reality arises from//
//the quantum substrate: Effective amplification they represent
accounts for the objective existence//
//of the einselected states of macroscopic quantum systems through
the redundancy of pointer state//
//records in their environment – through quantum Darwinism./
Brent
That paper, and others by Zurek, are the main reason I think that QM
might ultimately make sense. Zurek understands that entanglement with
the environment leads to essential non-unitary states. He concludes
the above paper with:
"Everett's insight -- the realisation that relative states settle the
problem of collapse -- was the key to these developments. But it is
important to be careful in specifying what exactly we need from
Everett and his followers, and what can be left behind. There is no
doubt that the concept of relative states is crucial. Perhaps even
more important is the idea that one can apply quantum theory to
anything -- that there is nothing \ab initio\ classical. But the
combination of these two ideas does not yet force one to adopt a "Many
Worlds Interpretation" in which all the branches are equally real."
Zurek cites this paper by Haliwell where he writes:
https://arxiv.org/pdf/quant-ph/9902008.pdf
/
//In this paper we have effectively shown that the decoherence condition
is a reflection of the information//
//storage capacity of the environment. That is, it is a lower limit on
the degree to which the histories may be fine-grained without the
information storage capacity of the environment being exceeded./
But I don't see how to use this limit on information to prune the MWI
branches.
Brent
Bruce
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