On Fri, Aug 16, 2019 at 2:07 PM Jason Resch <jasonre...@gmail.com> wrote:
> On Thu, Aug 15, 2019 at 8:43 PM Bruce Kellett <bhkellet...@gmail.com> > wrote: > >> On Fri, Aug 16, 2019 at 11:27 AM 'Brent Meeker' via Everything List < >> everything-list@googlegroups.com> wrote: >> >>> On 8/15/2019 5:06 PM, Bruce Kellett wrote: >>> >>> On Fri, Aug 16, 2019 at 9:25 AM Lawrence Crowell < >>> goldenfieldquaterni...@gmail.com> wrote: >>> >>>> I started reading this. It looks similar to the PR box argument. >>>> >>> >>> I have skimmed through it. It seems that Alice and Bob both split >>> locally according to the results they get, but then rely on magic to >>> prevent the incorrect pairs ever meeting. >>> >>> >>> I think you can interpret it as decoherence spreads at light speed from >>> Alice's measurement event and decoheres Bob's system when it comes within >>> the future light cone of Alice's measurement....and vice versa, which is >>> why it needs to assume MWI to maintain symmetry between Alice and Bob. >>> >>> Brent >>> >> >> It is paragraphs like this that seem to me to appeal to magic: >> >> Bruce >> >> "It is only when Alice and Bob interact that correlations are >> established. Let us assume for the moment that both Alice and Bob always >> push their buttons before interacting. The magical rule is that an Alice is >> allowed to interact with a Bob if and only if they jointly satisfy the >> conditions of the nonlocal box set out in Table 1 >> <https://www.mdpi.com/1099-4300/21/1/87/htm#table_body_display_entropy-21-00087-t001> >> . >> "For example, if Alice pushes button 1, she splits. Consider the Alice >> who sees green. Her system can be imagined to carry the following rule: You >> are allowed to interact with Bob if either he had pushed button 0 on his >> box and seen green, or pushed button 1 and seen red. Should this Alice ever >> come in presence of a Bob who had pushed button 1 and seen green, she would >> simply not become aware of his presence and could walk right through him >> without either one of them noticing anything. Of course, the other Alice, >> the one who had seen red after pushing button 1, would be free to shake >> hands with that Bob." >> >> "When they meet, the correlations they experience are simply due to the >> matching rule that determines which Alices are allowed to interact with >> which Bobs," >> >> > The scenario described in the paper isn't meant to be an account of > reality, it's a contrived scenario stated up front to be an imaginary > universe. The paper is meant to show that Bell does not disprove local > realism, only local hidden variables with single definite outcomes of > measurement. > > As for the magic, there is magic as the Non-local boxes in the scenario > operate by magic, and the rule that enforces consistency can be viewed as a > a form of magic too. In our world and in QM things are a bit different. > Perfect functioning non-local boxes are not possible, at best we can > violate Bell's inequality by 10% using entanglement. If one uses entangled > particles to build approximately functioning non-local boxes, then the rule > that prevents interacting with incompatible branches is the same > consistency rule that ensures if you make the repeated measurements of the > same observable you get consistent results. In the case of the entangled > particles, they have both already interacted (they'be both already measured > each other), so measuring one and finding it to be spin down, tells you > already the other one is spin up. So when you Alice receives a radio > message from Bob, she already knows the result. You can view meeting the > Bob as just another kind of measurement (and for the same observable). > That doesn't work for entangled particles in the singlet state either. Since the measurements by Alice and Bob are independent, both can get either up or down. They both split into two universes, separately and locally. But when Alice-up, say, meets Bob, she splits according to his result. So we get two possibilities: (Alice-up + Bob-up), and (Alice-up + Bob-down). For the case of aligned S-G magnets, the (Alice-up + Bob-up) combination is not possible. The impossibility of such a meeting requires exactly the same magic as the Brassard et al. paper proposes. 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 everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLTeunruW_EK8xTz%3D-SGS1f1522OykmEqDzNtydLM83O-A%40mail.gmail.com.
