> On 1 Oct 2019, at 19:37, 'Brent Meeker' via Everything List > <[email protected]> wrote: > > > > On 10/1/2019 4:38 AM, Bruno Marchal wrote: >>> On 1 Oct 2019, at 07:37, 'Brent Meeker' via Everything List >>> <[email protected]> wrote: >>> >>> >>> >>> On 9/30/2019 9:52 PM, Bruce Kellett wrote: >>>> I haven't read Carroll's book, it isn't released in Australia until >>>> November. I would be interested to see if he has a better account of Bell >>>> non-locality than Wallace. About the spread of "splitting": decoherence is >>>> a local physical interaction -- photons interacting with walls and the >>>> like. This clearly spreads at the speed of light (or less). But splitting >>>> is not really just decoherence. The trouble with Bell non-locality is that >>>> the splitting of worlds is not a physical interaction like decoherence. >>>> Bruno and others speak about a "spread of entanglement" as being >>>> associated with the splitting. But again, entanglement is the result of >>>> physical interaction, and the interaction of looking at a pointer to see a >>>> result is not really an entanglement interaction. I think that there is a >>>> lot of loose thinking about this "splitting" process. >>>> >>>> The absence of disallowed branches (Alice and Bob both seeing spin-up with >>>> aligned polarisers) is not a matter of worlds (branches) cancelling by >>>> destructive interference, because there is no interaction -- the light >>>> carrying information from the space like separated measurements is not >>>> coherent, so it can't interfere. If it were coherent, allowing >>>> interference, then that coherence itself would indicate non-locality. >>> But the copying of information as to the measurement result, quantum >>> Darwinism, is a physical interaction that writes the information into the >>> environment. So that we can imagine that both UP and DOWN information >>> spreads from Alice and also separately from Bob. Where they overlap in the >>> future they must correlate per QM. Why can't we suppose that the >>> inconsistent worlds cancel out. You say the light carrying the information >>> isn't coherent, but it's not just the light that carries the information; >>> it's information encoded in the wave function of the environment. So no >>> small part of the environment (like the light) is going to appear coherent, >>> but it's still going to be inconsistent with the opposite result and zero >>> out cross terms in the density matrix. That's essentially what the >>> mathematical process of taking the reduced trace does. >> Right. Then the non locality has disappeared from the wave equation at the >> start. > > No, Bruce's point is that it must be present at the start. Otherwise Bell's > inequality couldn't be violated.
Bruce agree that there is no FTL action, that is locality. The non locality is in the perspective view. It is not a global truth, as that is obvious if you agree that the wave function evolution is only a rotation in some space. Rotation are typically local, even in abstract spaces (which in Everett and with mechanism are the real thing). Now, with “one physical universe”, that non-local perspective implies some FTL action. Bruno > > Brent > >> The Wave act locally in the Hilbert space (or the von Neumann algebra, and >> we see non locality only from a branch/term perspective. But without >> collapse, the non locality does not involved neither FTL communication, nor >> any FTL influence (which, for a realist on a unique world would be as much >> embarrassing). That is why the violation of Bell’s inequality is a >> quasi-confimartion of the “other histories” being as real as our’s. >> >> Bruno >> >> >>> Brent >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "Everything List" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >>> email to [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/everything-list/82e40b4e-7a51-c2c7-2b37-2fbb5923e9b4%40verizon.net. > > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/acff7b2f-7674-708b-47ca-6c7ba1db393c%40verizon.net. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/702104E8-E97A-45A8-A4FD-F8C07D58286B%40ulb.ac.be.
