> On 1 Oct 2019, at 14:13, Bruce Kellett <[email protected]> wrote: > > On Tue, Oct 1, 2019 at 9:38 PM Bruno Marchal <[email protected] > <mailto:[email protected]>> wrote: > > On 1 Oct 2019, at 07:37, 'Brent Meeker' via Everything List > > <[email protected] > > <mailto:[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. > > How? The wave function itself is non-local.
It looks like that from the one term perspective, but the universal wave is local. It is “just” a rotation in some space. All wave are typically local. > > 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 every branch in the Everettian picture shows non-locality. Yes, but only due to the statistical interference between all terms of the wave. The non-locality just shows that we have to take into account the information even when it is no more accessible in direct or interactive way. > Where do the other branches make each branch actually local? You are still > not explaining anything. I am not trying to explain everything. I am just saying that the violation of Bell’s inequality does not prove any physical FTM influences. > > 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). > > Neither collapse nor FTL are the issue. We can agree that there is no FTL > action because that would amount to a local explanation -- the FTL exchange > would interact locally at each end. The effect is non-local because the > non-separable wave function is intrinsically non-local. Lorentz invariance > is intact because of the no signalling theorems. You lost me with “the wave function is intrinsically non local”. > > That is why the violation of Bell’s inequality is a quasi-confimartion of the > “other histories” being as real as our’s. > > As I said, the thought that Bell might be local in many worlds was really the > last hope for MWI being of any use. But all attempts to demonstrate this have > failed. The sort of mumbo jumbo you offer here is no better than Wallace's > obscurantism. It is up to those who believe in FTL to show them. If by non-locality you mean “appearance of action at a distance, but without any FTL”, the I think we agree. I can show that arithmetic entails intuitively and formally that type of inseparability of the observable. It comes from the fact that the first person cannot be aware of the UD-steps delays. Bruno > > Bruce > > -- > 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] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/CAFxXSLSPvk7vU6VHVx2ghaYPL%3Dpg1Vz4xhsccRfRxgOvyfNvwA%40mail.gmail.com > > <https://groups.google.com/d/msgid/everything-list/CAFxXSLSPvk7vU6VHVx2ghaYPL%3Dpg1Vz4xhsccRfRxgOvyfNvwA%40mail.gmail.com?utm_medium=email&utm_source=footer>. -- 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/99EB2C68-2B30-4F33-9012-FD26EA71983A%40ulb.ac.be.
