On Sun, Apr 17, 2016 at 7:34 PM, Bruce Kellett <bhkell...@optusnet.com.au> wrote:
> > The future light cones of the observers will overlap at a time determined > by their initial separation, regardless of whether they send signals to > each other or not. > Of course, I never meant to suggest otherwise. Imagining a central observer who receives messages about each experiment was just conceptually simpler than imagining an arbitrary system that is affected in some unspecified way by each experimenter's results along with every other part of that system's past light cone. But you certainly don't *need* to use that particular example. > >> This so-called "matching up" is pure fantasy. Who does this matching? If > the central umpire is to do the matching, he has to have the power to > eliminate cases that disagree with the quantum prediction. Who has that > power? > The laws of physics would do the matching in some well-defined mathematical way. I don't see this as fundamentally different from the fact that the laws of electromagnetism can be written in a form where the electric and magnetic potentials at each point in spacetime can be found by summing the potentials from all the charges and currents on the entire past light cone of that point (this neat approach is known as 'Lienard-Wiechert potentials', see https://www.av8n.com/physics/lienard-wiechert.htm for some discussion). Is it meaningful in that case to ask "who" is keeping track of each individual charge or current on the past light cone and adding up their potentials correctly to get the total? Also, what do you mean "eliminate cases"? Are you suggesting the frequencies of copies of each experimenter that get different possible results would have to be retroactively changed? I'm pretty sure that wouldn't be necessary, at least it isn't in the toy model I suggested. If on the other hand you just mean the laws are ensuring that you don't get combinations that aren't allowed by the laws themselves, again that just seems like the sort of thing you'd expect mathematical laws of physics to do. As I said, I don't understand the details of the Mark Rubin papers, but on p. 19-20 of the paper at http://arxiv.org/abs/quant-ph/0204024 he gives a more qualitative description of the model that the prior parts of the paper have explained mathematically, and it at least sounds as though it works in this way: "Information encoded in an operator at one place at an earlier time is transfered to operators at other places at later times in accordance with a local differential equation. (In a relativistic theory information is only transferred to later-time operators within the future light cone of the earlier-time operator.) Operator- valued wave packets corresponding to initially-separated particles may come into contact and exchange information. At any time, at any location, the value of the field operator is a weighted sum of products of initial-time field operators, as in (154), (155) (of course higher-order terms will in general be present). As one wave packet passes by another it may acquire contributions to this weighted sum which were “carried” to the interaction region by another wave packet corresponding to another particle. (E.g., via the O(ε) change to φ_V,[r]i due to the interaction term in eq. (154).) At later times operators in this wave packet will retain these contributions, serving as labels indicating that the encounter with the other wave packet took place. Depending on the nature of the initial conditions and the interaction, distant field operators at times subsequent to the interaction may be entangled in such a way that the results of measurements made upon them (when compared at still later times by means of some other causal interaction) are correlated to a degree in excess of that allowed by Bell’s theorem.5 As discussed in Ref. 22, correlations in the Everett interpretation are correlations of information exchanged in a causal manner between copies of measuring instruments and/or the states of awareness of observers, so these excess correlations in no way imply the presence of nonlocality." Jesse -- 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 post to this group, send email to firstname.lastname@example.org. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.