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Avatar of Ulrich Mohrhoff

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  1. Avatar of referee A
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    Report of referee A:

    I have read the manuscript "Quantum Nonlocality Explained", submitted to IJQF. The author's overall thesis appears to be that, in an interpretation of quantum mechanics in which certain standard assumptions of spatiotemporality are rejected, the quantum correlations (which Bell argued prove the existence of nonlocal, i.e., faster-than-light, causation) can instead be understood in a different way. It is not really clear to me what this different way is supposed to be. That is, I cannot tell whether the author thinks that his interpretation provides a *local* explanation of the correlations, or instead one that is, while still nonlocal, superior in some way to the explanations provided by the several extant realistic versions of QM. Probably he thinks that the very idea of clearly distinguishing local from nonlocal explanations is invalid, insofar as it presupposes standard notions of spatiotemporality. But then it is not clear to me what the point is.

    Overall, I cannot recommend the paper for publication, for the simple reason that I find it utterly incomprehensible. The part I found clearest was the passage at the end of section 4 in which the author makes the point that the usual causal story involved in two subsequent spin measurements on a single particle is time-asymmetric. This reminded me of the work of, for example, Huw Price and Ken Wharton, and I expected the paper to turn to general notions of time-symmetry and retro-causation and perhaps somehow apply the same kind of analysis to the case of two spin measurements on spatially-separated (and spin-entangled) particles. But instead, in the following section on "Quantum Nonlocality", the author instead retreats to the (to me) incomprehensible philosophical word play that had dominated the first several sections of the paper. But to me, the idea that "the causality responsible for quantum theory's violation of remote outcome independence need not be of the familiar spatiotemporal kind" does not provide anything I would call an *explanation* of quantum nonlocality. I'm sure the author thinks that his fleshing-out of the particular "kind" of non-spatiotemporal causation that he discusses does provide an explanation of something. But as I said, all of this is, to me, completely incomprehensible; it is like the meaningless word play of the continental philosophers and is simply not in the same universe as what I would regard as an explanation of the Bell-inequality-violating quantum correlations that is appropriate in physics.

  2. Avatar of referee A
    referee A at | |

    A few comments in response to the author's comments on my earlier comments:

    "Quantum mechanics itself implies that standard assumptions of spatiotemporality *must* be rejected."

    I don't agree. There are several extant theories (e.g., spontaneous collapse theories, the de Broglie - Bohm pilot-wave theory, etc.) which explain the correlations in a way that doesn't involve any rejection of what I would think of as "standard assumptions of spatiotemporality". I mean, they explain the correlations *non-locally*, as we know from Bell any theory must do, so there are questions about whether and how such theories are compatible with fundamental relativity. But they don't give up on the project of giving a coherent spatiotemporal physical account, and indeed they succeed (at very least) in proving that this is possible. Given that, I can't understand why anybody would want to give up on that project.

    On a related point, the author writes that "Physical space ... cannot be modeled as an actually existing manifold of points." But this is simply not true. It can. The theories mentioned above allow a perfectly standard "actually existing manifold of points" account of space.

    Finally, in response to the author's paragraph explaining why he doesn't find it surprising that I found the paper incomprehensible, I don't think his remarks are on target at all. I work in foundations of physics and am perfectly comfortable with philosophical discussion of theories. The problem with the paper is not that it doesn't contain enough mathematical formulas, but that what is said is to me incomprehensible. The paper announces in its title that it will "explain" quantum nonlocality. But what I find is instead a very vague and metaphysical story, with at best flimsy evidence supporting it, whose purpose appears to be to reconcile us to the view that nothing like an actual explanation of quantum nonlocality is possible. But there are already theories that provide actual (candidate) explanations. Perhaps the author's views would be more convincing if he confronted these existing explanations and tried to show why they are inadequate, or how (appearances to the contrary notwithstanding) they exhibit the properties he thinks are required. Because as things stand now, they look like simple counterexamples to a bunch of the ideas (like that normal notions of spatiotemporality are untenable) that seem to motivate his proposals.

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