On Sunday, November 26, 2017 at 8:22:37 AM UTC-6, Bruno Marchal wrote: > > > On 24 Nov 2017, at 00:15, Lawrence Crowell wrote: > > I am new to this list and have not followed all the arguments here. In > weighing in here I might be making an error of not addressing things > properly. > > Consider quantum entanglements, say the entanglements of two spin 1/2 > particles. In the singlet state |+>|-> + |->|+> we really do not have the > two spin particles. The entanglement state is all that is identifiable. The > degrees of freedom for the two spins are replaced with those of the > entanglement state. It really makes no sense to talk about the individual > spin particles existing. If the observer makes a measurement that results > in a measurement the entanglement state is "violently" lost, the > entanglement phase is transmitted to the needle states of the apparatus, > and the individual spin degrees of freedom replace the entanglement. > > We have some trouble understanding this, for the decoherence of the > entangled state occurs with that state as a "unit;" it is blind to any idea > there is some "geography" associated with the individual spins. There in > fact really is no such thing as the individual spins. The loss of the > entangled state replaces that with the two spin states. Since there is no > "metric" specifying where the spins are before the measurement there is no > sense to ideas of any causal action that ties the two resulting spins. > > > I agree. But we can trace out locally the prediction possible, and this > explains locally the results in the MW view, not so in the mono-universe > view which requires some (incomprehensible) action at a distance. That is > why I took the Aspect confirmation that QM violate Bell's inequality (well > the CHSH's one) as a confirmation of the physical existence of the parallel > computations/worlds, and not of action at a distance. >
The MWI has worlds in superposition, which as you say is preferable to the idea of some action at a distance. I have had many email battles with people over this, but this idea of action at a distance or its space plus time version of retrocausality keeps coming up. It is like shooting ducks in a carnival shooting gallery; you can shoot them down but the damned things keep popping back up. This does not mean I am a convert to the MWI interpretation. In many ways M-theory of D-branes is more friendly to the Copenhagen Interpretation, where D-branes are condensates of strings that form a classical(like) structure that act in ways as decoherence systems on strings. The ψ-epistemic viewpoint has some merits with respect to looking at the classical world as a way that information or Bayesian updates can be made on quantum systems. The problem of course with this is it leads into a sort of quantum solipsism The converse ψ-ontological perspective avoids this classical-quantum dichotomy, but I have always found problems with the issue of contextuality. This goes back to my pointing out how MWI fails to indicate how an observer is "pushed" into a particular eigenbranch of the world and how this occurs at a given time. With the lack of simultaneity in special relativity and spacetime in general what is the spatial surface at which the world wave function appears to split according to an observer? > > > > > This chaffs our idea of physical causality, but this is because we are > thinking in classical terms. There are two ways of thinking about our > problem with understanding whether quantum mechanics is ontic or epistemic. > It could be that we are a bit like dogs with respect to the quantum world. > I have several dogs and one thing that is clear is they do not understand > spatial relationships well; they get leashes and chains all tangled up and > if they get wrapped up around a pole they simply can't figure out how to > get out of it. In this sense we human are simply limited in brain power and > will never be able to understand QM in some way that has a completeness > with respect to causality, reality and nonlocality. There is also a far > more radical possibility. It is that a measurement of a quantum system is > ultimately a set of quantum states that are encoding information about > quantum states. This is the a quantum form of Turing's Universal Turing > Machine that emulates other Turing machines, or a sort of Goedel > self-referential process. If this is the case we may be faced with the > prospect there can't ever be a complete understanding of the ontic and > epistemic nature of quantum mechanics. It is in some sense not knowable by > any axiomatic structure. > > > I agree and much more can be said. In fact quantum weirdness can be proved > to be a consequence of Mechanism (informally with some thought experience), > and formally with the Gödel-Löb-Solovay theory of self-reference (which is > *the* theory provided by the universal machine itself when looking inward > deep enough. > I can give you references if you are interested. And yes, it is radical > ... for Aristotelian materialists, which believes that physics *is* > metaphysics. The arithmetical explanation of the quantum is of course > rather natural for platonic Pythagorean people. What is nice, is that the > Gödel-Löb logics explains also the quanta as the sharable part of a more > general consciousness or qualia theory. You might look at: > > Marchal B. The computationalist reformulation of the mind-body problem. > Prog Biophys Mol Biol; 2013 Sep;113(1):127-40 > > Marchal B. The Universal Numbers. From Biology to Physics, Progress in > Biophysics and Molecular Biology, 2015, Vol. 119, Issue 3, 368-381. > > B. Marchal. The Origin of Physical Laws and Sensations. In 4th > International System Administration and Network Engineering Conference, > SANE 2004, Amsterdam, 2004. Available here: > http://iridia.ulb.ac.be/~marchal/publications/SANE2004MARCHALAbstract.html > > Bruno > I am familiar with Löb's theorem, if it can be shown a statement "a proposition is provable in a system" is true then the proposition is provable in that system. That sounds almost tautological, and in modal logic it is □p → p. The modus tolens is ⌐p → ⌐□p (⌐ = NOT) which is not the same as p → □p. The □ means necessarily and ⌐□⌐ means not necessarily not or possibly abbreviated as ◊ and so ⌐p → ◊⌐p. Godel's theorem illustrates a case where p → □p is false; a proposition about an math system is true, but is not necessarily or provably true. If that is false then ⌐□p → ⌐p is false or ◊⌐p → ⌐p is false. We can then only say that p being true is "possible." This seems to have some connection with quantum measurement and the update on knowledge of a system with prior probabilities = plausible estimates. I wrote a paper involving Gödel's theorem, but it was not that well received. I will take a look at the paper on the web. I have a certain cautionary issue with these sorts of issues. I have learned lots of physicists take some umbrage with it. LC > -- 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 everything-list@googlegroups.com. 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