> On 3 Dec 2018, at 10:35, Philip Thrift <cloudver...@gmail.com> wrote:
> On Sunday, December 2, 2018 at 8:17:54 PM UTC-6, Brent wrote:
> On 12/2/2018 5:14 PM, Philip Thrift wrote:
>> On Sunday, December 2, 2018 at 4:25:04 PM UTC-6, Brent wrote:
>> On 12/2/2018 11:42 AM, Philip Thrift wrote:
>>> On Sunday, December 2, 2018 at 8:13:48 AM UTC-6, agrays...@gmail.com <> 
>>> wrote:
>>> Obviously, from a one-world perspective, only one history survives for a 
>>> single trial. But to even grossly approach anything describable as 
>>> "Darwinian", you have to identify characteristics of histories which 
>>> contribute positively or negatively wrt surviving but I don't see an 
>>> inkling of that. IMO, Quantum Darwinism is at best a vacuous restatement of 
>>> the measurement problemt; that we don't know why we get what we get. AG
>>> In the sum over histories interpretation - of the double-slit experiment, 
>>> for example - each history carries a unit complex number - like a gene - 
>>> and this gene reenforces (positively) or interferes (negatively) with other 
>>> history's genes in the sum.
>> But I thought you said the ontology was that only one history "popped out of 
>> the Lottery machine"?  Here you seem to contemplate an ensemble of 
>> histories, all those ending at the given spot, as being real.
>> Brent
>> All are real until all but one dies.
>> RIP: All those losing histories.
> The trouble with that is the Born probability doesn't apply to histories, it 
> applies to results.  So your theory says nothing about the probability of the 
> fundamental ontologies.
> Brent
> The probability distribution on the space of histories is provided by the 
> path integral. 

I agree, and this statement can be made rather rigorously in the approach of 
Griffith and Omnes, except that Omnes eventually add an axiom of irrationality 
to extract a unique physical reality from the formalism. He said it, at least, 
explicitly: like saying “and now there is a miracle”. He says that at this 
stage, we need irrationalism. But that appears in the last ten sentences of a 
rather quite rational book. 
Well, the point is that we can generalise the Born rule for making sense on 
some probabilities on "consistent histories”.
(But I am in trouble (now) on how to handle the GHZ state in term of (Griffith 
and Omnes)-histories (3-particle-GHZ = 1/sqrt(2)(up up up + down down down)).

> Backward causation, hidden variables and the meaning of completeness 
> [ https://www.ias.ac.in/article/fulltext/pram/056/02-03/0199-0209 ]
> Feynman’s path integral approach, calculation of the probability of the 
> outcome in question depends on an integration over the possible individual 
> paths between the given initial state and the given final state, each 
> weighted by a complex number. The fact that the weights associated with 
> individual paths are complex makes it impossible to interpret them as real 
> valued probabilities, associated with a classical statistical distribution of 
> possibilities.
> However, there is no such difficulty at the level of the entire ‘bundle’ of 
> paths which comprise the path integral. If we think of the hidden reality as 
> the instantiation not of one path rather than another but of one entire 
> bundle rather than another, then the quantum mechanical probabilities can be 
> thought of as classical probability distributions over such elements of 
> reality. (For example, suppose we specify the boundary conditions in terms of 
> the electron source, the fact that two slits are open, and the fact that a 
> detector screen is present at a certain distance on the opposite side of the 
> central screen. We then partition the detector screen, so as to define 
> possible outcomes for the experiment. For each element O_i of this partition, 
> there is a bundle B_i of Feynman paths, constituting the path integral used 
> in calculating the probability of outcome O_i . We have a classical 
> probability distribution
> over the set of such B_i .
> One could stop at history bundles as the sample space, or the "hidden 
> reality" could be that one history is selected at random from the history 
> bundle. That could occur with time symmetry (retrocausality): The one path is 
> chosen at random from a history bundle at the source in the present from the 
> distribution determined on the history bundles in the future.

With mechanism, the randomness and the unicity is a first person (plural) 
experience only, and seems to me no more astonishing than in the amoeba 
duplication, or than in the Helsinki—> Washington/Moscow duplication, as seen 
from the first person ways.


> - pt
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