On 4/4/2022 8:46 PM, Bruce Kellett wrote:
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?

I couldn't figure out how the "labels" actually implemented contrary observers meeting?


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.

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