On Tue, Apr 5, 2022 at 12:15 PM Brent Meeker <meekerbr...@gmail.com> wrote:

> This paper https://arxiv.org/pdf/quant-ph/0103079.pdf gives an explicit > account of an EPR type experiment which says observers are "labeled" so > that only the compatible observes can communicate. > > So, the splitting of each observer into copies at each measurement > interaction is represented by the local dynamics of the operators > describing their states of awareness relative to what they were at the > initial time t0; in particular, the possibilities for interaction of > observers of entangled systems are determined by the labels attached to the > operators. Determination of the number of each type of observer-copy > produced at each splitting, as well as the specific state of awareness of > each type of observer-copy, involves information 14 about the initial > conditions of the system, information which in the Heisenberg picture is > contained in the time t0 state vector. (DeWitt (1998) emphasizes that > quantum systems are “described jointly by the dynamical variables and the > state-vector.”) Just as observers or other entities may be regarded as > receiving and carrying with them, in a local manner, the labels described > above, they may also be envisioned as carrying with them in a similarly > local manner the requisite initial-condition information. > Since one cannot argue for the existence of counterfactual instruction > sets, the conditions of Bell’s theorem do not apply. Had angles other than > those that actually were used been chosen for the analyzer magnets, copies > of each observer carrying labels appropriate to those angles would have > resulted. There are indeed “instruction sets” present; but they determine, > not the results of experiments which were not performed but, rather, the > possibilities for interaction and information exchange between the Everett > copies of the observers who have performed the experiments. > Bohr’s reply to EPR can also be reinterpreted in the present context. > Regarding correlations at a distance, Bohr (1935) states that “of course > there is in a case like that just considered no question of a mechanical > disturbance of the system under investigation during the last critical > stage of the measuring procedure. But even at this stage there is > essentially the question of an influence on the very conditions which > define the possible types of predictions regarding the future behavior of > the system.” The Everett splitting and labeling of each observer > constitutes just such an influence, determining the possible types of > interactions with physical systems and observers which the observer can > experience in the future without in any way producing a “mechanical > disturbance” of distant entities. > The Everett interpretation in the Heisenberg picture thus removes > nonlocality from the list of conceptual problems of quantum mechanics. The > idea of viewing the tensor-product factors in the Heisenberg-picture > operators as in some sense “literally real” introduces, however, a > conceptual problem of its own.3 Entanglement via the introduction of > nontrivial “label” factors is not limited to interactions between two or > three particles; each particle of matter is labeled, for eternity, by all > the particles with which it has ever interacted. What is the physical > mechanism by means of which all of this information is stored? The issue of > “where the labels are stored” may seem less problematic in the context of > the Everett interpretation of Heisenberg-picture quantum field theory. > After all, in quantum field theory, operators corresponding to each species > of particle and evolving according to local differential equations already > reside at each point in spacetime. (In the EPRB and GHZM experiments the > particles in question are considered to be distinguishable and so may be > treated, for purposes of analyzing the experiments, as quanta of different > fields. More complicated objects, such as observers and magnets, might be > approximated as excitations of effective composite fields, following, e.g., > Zhou et al. (2000).) > Even in the event that such a program for a literal, indeed > mechanistic picture of measurement in quantum field theory cannot be > realized, it remains the case that Everett’s model for measurement in the > Heisenberg picture provides a quantum formalism which is explicitly local > and in which the problem of Bell’s theorem does not arise. > What do you make of this? Others have referred me to the Rubin paper. I have looked at it, and remain unimpressed. He claims that "Bell's theorem is avoided because the counterfactual reasoning that leads to it is not required and cannot be justified." This is nonsense. Bell's theorem does not require counterfactual reasoning, and the experiments by Aspect and others only record the results of measurements that were actually made-- there is no reference to measurements that were not performed at other angles. Measurements that are not performed have no results. More seriously, he has an undisguised appeal to magic in statements such as: "When the two observers -- or, more precisely, the two pairs of observer-copies -- exchange information about the results of their measurements, it is the attached labels which ensure that the "correct" copies of each of the observers interact; e.g., preventing two observers-copies who have both observed spin-up from communicating." A more direct appeal to magic is hard to envisage. The 'labels' that he says the Heisenberg picture attaches do no work that was not already done by the actual results. Furthermore, there is no indication as to what interaction occurs when the observers meet, and no indication as to how this supposed interaction does the work that is required of it. What happens to the "incorrect" aobserver pairs? This is unbridled nonsense, and I am sick of responding to nonsense papers of this sort. 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/CAFxXSLTWq063pDpsWbHwZcxXT4pg3i7s1YjzrzQnF%3DA19KOirQ%40mail.gmail.com.