Edward,

In his SEP article on the Copenhagen Interpretation Jan Faye says this, which I immediately thought of when I read your paper:

"In general, Bohr considered the demands of complementarity in quantum mechanics to be logically on a par with the requirements of relativity in the theory of relativity. He believed that both theories were a result of novel aspects of the observation problem, namely the fact that observation in physics is context-dependent. This again is due to the existence of a maximum velocity of propagation of all actions in the domain of relativity and a minimum of any action in the domain of quantum mechanics. And it is because of these universal limits that it is impossible in the theory of relativity to make an unambiguous separation between time and space without reference to the observer (the context) and impossible in quantum mechanics to make a sharp distinction between the behavior of the object and its interaction with the means of observation (CC, p. 105)."

Just curious as to whether you see it as analogous to your own approach. Incidentally, I was also led to download your longer July 2011 paper from the Arxiv and am chewing on it.

    Thank you very much for your encouraging comments. The reply to the

    question in your longer post is given below.

    JCNS:

    Thanks for your post. Several papers that concern issues surrounding quantum

    measurements have been submitted to the contest, and they reflect a wide variety

    of views. So there should be plenty of interesting discussion.

    Vladimir,

    Thank you for your post. I read your paper, and it is well written.

    It covers a lot of ground, so I will not try to comment on all of it.

    Regarding Q5, on the point particle vs. wave issue, I have not had a chance

    to look at Eric Reiter's results, but it would be interesting to see how

    the photon (or photon wave) was detected in two places. I assume that it

    was a nondestructive detection, since an absorption of a single photon

    in two places would violate conservation of energy. Aharonov and his colleagues

    have described weak measurement techniques which in some cases can be interpreted

    as (more or less) direct observations of the wave function, so some types of

    double detections are possible.

    Regarding Q6, you say that "the true explanation is that the two photons are in

    the same state from beginning to end", but Bell's theorem shows that this

    cannot be the case. Maudlin's book (Quantum Non-Locality and Relativity) gives an

    excellent presentation of the argument, and there are several simple on-line

    descriptions, for example, the Wikipedia entry on the Clauser-Horne-Shimony-Holt

    (CHSH) inequality.

    This is an excellent question (and therefore not an easy one to answer).

    I would not agree with the analogy that Bohr was trying to draw. Although I am

    arguing that we need to adopt a substantially new perspective toward relativity,

    Bohr was working in the context of the standard spacetime view of relativity. It

    is against this viewpoint that we have to judge his attempts to interpret quantum

    theory. The standard view of relativity as a description of spacetime is logically

    coherent, even if, ultimately, it cannot be successfully merged with quantum theory.

    For all his struggles to do so, I don't think that Bohr succeeded in constructing

    a logically coherent interpretation of quantum theory. Although relativity had some

    surprising consequences (particularly regarding the nature of time), it is fully

    comprehensible (as a classical theory). We cannot make an unambiguous separation

    between time and space, but we understand fully why this is so.

    In interpreting Bohr's views it is important to keep in mind that he was

    writing before Bell demonstrated the radically nonlocal nature of what occurs

    during some quantum measurements. Clearly, In the wake of the EPR paper, and in

    formulating his reply to it, Bohr had some rough idea of the challenge posed by

    nonlocality, and Faye makes the point that Bohr appears to have seriously changed

    his interpretation of the quantum formalism in response to the challenge. But it

    does not appear that he fully grasped the need to explain the nonlocal correlations

    that Bell (later) clearly identified.

    As I said, this is a very good question, and it probably will require

    more discussion.

    • [deleted]

    • Post #10

    Hi Edward,

    this is an interesting and nicely written essay. I have the following thought for you: when one takes the different physical scales involved, things may look different. Example: I can make an apparatus where when I press a switch, an impulse is sent down two signalling paths that have been very carefully manufactured to be identical in length, to reach identical activators, say 5cm apart, that each send out a laser pulse when they receive the signal. These pulses will be emitted simultaneously if the signalling paths are equal to sufficient accuracy. From the micro-viewpoint this will look acausal (light is emitted simultaneously from spacelike separated objects), but from a macro viewpoint there is no problem; it is the macro structure that has enabled the simultaneity at the microlevel (and that chain of causation can off course be traced at the micro level). This is an example of the interscale effects that can occur in quantum physics: from the Copenhagen view you just regard the macro apparatus as a single entity whose internal workings are of no concern, and then macro apparatuses can reach down in an a-casual way to the micro level.

    Overall the comment is that any physical description has averaging scales associated with it. The interscale interactions resulting can be interesting.

    George Ellis

      • [deleted]

      • Post #11

      Dear Edward Gillis,

      A well written essay. I think you are correct that both space-time, relativity and non deterministic physics have to be accepted. How they can co-exist without contradiction has been an interest of mine for a long time. I agree with Vladimir Tamari in particularly liking your conclusion.

      Good luck in the competition.

        Edward,

        "But, in order to make current theory logically coherent, we need to realize that relativity is rooted as much in the indeterminism that characterizes quantum theory as in the structure of space and time."

        Do time and space both have a role in relativity's indeterminism and are causal relationships dubious or non-existent as time passes?

        I'm somewhat confused.

        Jim

          4 days later

          Professor Ellis:

          Thank you for your interest.I have long admired your work in cosmology and your willingness to deal with controversial scientific issues. Your work outside academia is truly laudable.

          Your essay on top-down causation is interesting and insightful. You present a very nice explanation of how causation on different levels operates by defining constraints.

          I would agree with your overall comment that "any physical description has averaging scales associated with it", and that the interscale interactions are interesting. But I think that it is important to be able to explain, at least in principle, how these interactions work. My problem with the Copenhagen Interpretation (C.I.) is that it says that we really cannot analyze what happens across the micro-macro interface. Your example of the two simultaneously firing lasers illustrates this nicely. It is clearly causal on a macroscopic scale, and it is true that at least some versions of C.I. would treat the apparatus as a single "black box",so that the precise operation on a micro level might be viewed as acausal. However, as you point out, the chain of causation can be traced at the micro level. So we can construct a locally deterministic account of the process in which all influences propagate within the light cone. There is no genuine superluminal or acausal influence in this case, even if some versions of C.I. suggest this.

          In contrast, Bell-EPR correlations indicate that, in certain situations,

          there are real superluminal effects. To explain these on a micro level we need to revamp our understanding of spacetime structure to allow for these nonlocal

          processes. I believe that we can do this and still preserve the relativistic

          description of spacetime because of the symmetric character of the probabilistic law governing these processes [ P(A|B) = P(B|A) ].

          Ed

          Georgina,

          Thanks for your comments. I read your essay, and it offers a number of very interesting perspectives. You address a lot of the issues that we need to face in trying to achieve a unified understanding of relativity and quantum theory. Good Luck.

          Ed

          Jim,

          Thanks for your question. I believe that we should look at space as a 3 dimensional manifold that evolves in time. This would disrupt the (partial) unification of space and time that is achieved in conventional views of relativity, but it makes it possible to understand what happens in quantum measurements. Bell's work and subsequent analysis have shown that the effects of measurements are both nonlocal (superluminal), and nondeterministic. These are extremely difficult to fit within a conventional 4-dimensional relativistic spacetime. Fortunately the form of indeterminsism that occurs is regulated by a special probability rule (the Born Rule). This rule has the special property that it is symmetric with respect to possible outcomes of measurements. So if 2 spacelike-separated measurements are made on an entangled system, the probability of a B outcome of measurement 2, given that an A outcome of measurement 1 has already occurred, is equal to the probability of an A outcome of measurement 1, given that a B outcome of measurement 2 has already occurred. This means that there is no way to determine which of the 2 measurements occurred first. So the relativistic description of spacetime which allows us to sequence spacelike separated events in either order remains consistent with all physical observations. It is the special form of indeterminism that insures this consistency.

          Ed

          Ed,

          "I argue that relativity is not a guarantor of local causality, and is not about ontological features of spacetime." What impact would this have on my belief that the forces of gravitation might be cancelled, at least by advanced civilizations? Are message carriers like the graviton and the embedded anti-graviton -- assuming they exist -- possibly discontinuous?

          Jim

          • [deleted]

          • Post #17

          Your paper makes a salient point. I will be posting an essay here in the near future which touches on this problem. I think the question that needs to be raised is how fundamental is locality. Quantum mechanics has a representation according to configuration variables in spacetime, or the momentum conjugate, but quantum state are fundamentally independent of such representations. Quantum wave equations are partial differential equations which define an oscillator at every point on a spatial manifold. Locality is "imposed" by assigning equal time commutators on this spatial slice. However, the wave equation is defined according to partial derivatives with time ∂_t which is a local time direction determined by the frame of an observer. If we were to quantize spacetime itself there would be no manner in which a Born rule exists in general. The reason is that light cones near the Planck scale become indistinct. A propagator of quantized spacetime according to standard QFT propagates this on spacetime, which runs into trouble.

          I think then that spacetime is emergent from nonlocal or noncommutative geometry on a deeper level. In the reasoning of noncommutative geometry, geometry is replaced with groups. Underneath spacetime I think exists a quantized system of nonlocal amplitudes. At lower energy with the emergence of spacetime this enforces the Born rule for quantum waves at this larger scale.

            • [deleted]

            • Post #18

            Edward,

            While your essay is quite dense for those of us with little formal education in physics, it does contain some interesting insights and seems to go in the right direction in terms of correcting the various misconceptions built into the current structure. I especially found your analogy of information with temperature quite interesting, since it mirrors some of my own perceptions and thus provides some deeper insight into the issue of non-locality, which seems to be a bit of a mathematical artifact, but difficult to unravel. I do think the concept of temperature is greatly overlooked, as a window into non-linear systems. While the focus is usually on its formal molecular definition, everything from cosmic background radiation, to economic statistics could be thought of as forms of temperature. E.O. Wilson described the insect brain as a thermostat and it could be argued that radios, as well as many other forms of electronic devices are also, as your profession suggests you well understand.

            My own essay goes into a slightly different form of sensory misconception, the perception of time. We experience it as a series of events, from past to future and physics re-enforces this assumption by treating it as a measurement, but the actual physical process is the changing configuration of what is extant, collapsing probabilities into actualities. The future becoming the past. This makes it an effect of action(rate of change), similar to temperature(level of activity). Digging down into this, time dilation is due to changes in the level of atomic activity affecting the rate of macroscopic change.

            Spacetime is then correlation of distance and duration, not causation of action. One could easily use ideal gas laws to formulate "temperaturevolume," but we don't confuse the needle with the scale, as we do with time.

            Good luck.

              5 days later

              Jim,

              I don't think that what I am saying has any direct implications one way

              or the other concerning possible ant-gravity effects. There was a very nice

              paper by Scott Menary posted on the physics archive this past week,

              explaining why we are fairly sure that there are no anti-gravity effects:

              http://arxiv.org/abs/1207.7358.

              Concerning "messenger" particles: they generally have to propagate in a

              continuous manner.

              Ed

              Lawrence,

              I look forward to reading your paper. What you say about the Born

              rule is interesting. I would agree that the rule applies at the level of

              macroscopic observations, and that it should be explainable in terms of more

              fundamental processes. One key feature of it, however, is its symmetry: the

              probability of A, given a B outcome is equal to the probability of B, given

              an A outcome. I believe that this symmetry at a macroscopic level probably

              stems from some more fundamental symmetry principle.

              The possibility that spacetime is emergent is interesting to

              consider. I have not really addressed it here, other than to speculate that

              the partial unification of space and time that is achieved in relativity is

              dependent on the probabilistic nature of quantum theory.

              Ed

              John,

              Thanks for your comments. I read your essay, and you make some

              interesting points. The possible connections between time and thermodynamic evolution are well worth exploring.

              Ed

              • [deleted]

              • Post #22

              Ed,

              Thanks for the appreciation.

              Unfortunately physics will have to look beyond its current static modeling to really understand the relationship between time and thermodynamics. That's why I keep droning on about this particular point about time not being an essentially static vector from past to future, but the dynamic process by which the future becomes past.

              11 days later

              Edward,

              I agree, human intuition has played a very active part in our understanding of nature. Human intuition is partially due to our human knowledge as well as fundamental facts of nature as they appear in different context in human observations.

              The main task of physics/ Pico-physics is to bring forward the facts of nature in such a fashion that they are universally applicable (and not contradicted in any context). This may result into one or more set of universally applicable laws. The completion of the set is determined by complete explanation of human knowledge.

              Historically, it is seen that collection of human knowledge has preceded the formulation of laws. Scientists are trying there best to change this sequence, being upbeat on observation. Cold fusion, neutrino traveling faster than light, Higgs boson are all examples of this urge to be able to change the sequence (laws follow collection and organization of knowledge). This will be possible when the set of laws is complete.

              For Cat and laser pointer, and relationship to continuity of path, I believe it is due to conservation as seen in collected knowledge base, that intuitively brain even in animals with limited memory has a strong perception of continuity of path. It is not other way round; continuity of path is due to human intuition. The example only proves the point; universal laws are independent of object and observer.

              Thanks and Regards,

              Vijay Gupta

                • [deleted]

                • Post #24

                Ed,

                Re: locality. As you're probably aware, the Bell's Theorem debate has found its way here, as was doubtless inevitable, with the JC and THR ensemble noisily unreconstructed. The best response to this intransigence IMO is to double down.

                Do you see the Leggett inequality violations in the experiments by the Zeilinger and Gisin groups, coupled with the long and vast history of Bell violations, as relevant to your own thesis? If you want you could also bring in the Gisin group's moving reference frame experiment(s) specifically directed at relativistic Bohm, and Antoine Suarez' Before-Before gedankens. Also there's Charles Tresser's papers which argue that the locality assumption is unnecessary for violation of Bell.

                The above pretty much exhausts my knowledge of the avant-garde stuff. Quite conceivably there's more. I don't know what essayist apart from yourself in the current crop thus far might both want and be able to address even part of it.