On 11/7/2019 2:37 PM, Bruce Kellett wrote:
On Fri, Nov 8, 2019 at 9:26 AM 'Brent Meeker' via Everything List <everything-list@googlegroups.com <mailto:everything-list@googlegroups.com>> wrote:On 11/7/2019 1:58 PM, Bruce Kellett wrote:On Fri, Nov 8, 2019 at 8:53 AM 'Brent Meeker' via Everything List <everything-list@googlegroups.com <mailto:everything-list@googlegroups.com>> wrote: On 11/7/2019 1:40 PM, Bruce Kellett wrote: On Fri, Nov 8, 2019 at 6:35 AM 'Brent Meeker' via Everything List <everything-list@googlegroups.com <mailto:everything-list@googlegroups.com>> wrote:On 11/7/2019 12:21 AM, Philip Thrift wrote:On Wednesday, November 6, 2019 at 7:27:32 PM UTC-6, stathisp wrote: On Thu, 7 Nov 2019 at 11:15, Bruce Kellett <bhkel...@gmail.com> wrote: On Thu, Nov 7, 2019 at 11:00 AM Stathis Papaioannou <stat...@gmail.com> wrote: The universe as a whole is determined in every detail, and random choice of the observer in measuring a particle is not really a random choice. If you believe that, you believe in magic sauce. It is a consequence of Many Worlds that there is no true randomness, but only apparent randomness. If Many Worlds is wrong, then this may also be wrong. Randomness in choice of measurement is required for the apparent nonlocal effect when considering entangled particles.-- Stathis PapaioannouThat's what *Many Worlds* implies. The mystery is: Why do (according to the science press in the wake of Sean Carroll's book) so many people think Many Worlds is a good scientific idea (or the best idea, according to the author).Because it treats measurement as just another physical interaction of quantum systems obeying the same evolution equations as other interactions. But you can do that (viz. accept that people, and measuring instruments, and everything else are basically quantum mechanical) without adopting the "many worlds" philosophy.ISTM that creates problem for defining a point where one of the probabilities becomes actualized. MWI tries to avoid this by supposing that all probabilities are "actualized" in the sense of becoming orthogonal subspaces. There are some problems with this too, but I see the attraction. You can always find problems with any approach. What I particularly dislike about MW advocates (like Sean Carroll) is that they are dishonest about the number of assumptions they have to make to get the SWE to "fly". Particularly over the preferred basis problem and Born rule. Zurek comes closer, and he effectively dismisses the "other branches" as a convenient fiction.Yeah, I like Omnes' dictum, "It's a probabilistic theory, so it predicts probabilities. What more do you want?" But it still leaves that gap between the density matrix becoming diagonal FAPP and one subspace becoming actual FR (for real), not just FAPP. If you take a purely epistemic view the gap is just in your belief changing. But if you keep an ontological view the matrix is only diagonal in some preferred basis and it's not necessarily even approximately diagonal in some other basis. It seems the other bases are an inconvenient fiction. :-) It seems to come down to explaining that Zurek's quantum Darwinism necessarily picks out the basis in which our brains will form beliefs and they will agree on that belief as to what "really happened".Maybe our brains see it in this way because "that is really what happened". It is stochastic, but so what? We are used to updating probabilities on the basis of new evidence. Quantum Darwinism is a way of explaining that the world itself determines what is real.
Zurek uses quantum Darwinism and envariance to show there's a preferred basis and the Born rule is the way to assign probabilities to them once decoherence has acted. But he doesn't seem to say that one result or another is realized via the quantum Darwinism. Rather he's satisfied like Omnes' to say "It's a probabilistic theory so you get predictions of probabilities." Then observing one, you discard the others as failed predictions. He doesn't think of the quantum Dawinism as competition between different preferred basis outcomes to select one as realized. At least that's what I think he says.
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