> On 11 Aug 2019, at 14:09, Bruce Kellett <[email protected]> wrote: > > On Fri, Aug 9, 2019 at 7:25 PM Bruno Marchal <[email protected] > <mailto:[email protected]>> wrote: > On 9 Aug 2019, at 02:59, Bruce Kellett <[email protected] > <mailto:[email protected]>> wrote: >> On Thu, Aug 8, 2019 at 6:50 PM Bruno Marchal <[email protected] >> <mailto:[email protected]>> wrote: >> > On 7 Aug 2019, at 21:04, 'Brent Meeker' via Everything List >> > <[email protected] >> > <mailto:[email protected]>> wrote: >> > >> > On 8/7/2019 6:40 AM, Bruno Marchal wrote: >> >> It is like the difference between the human existence and the human non >> >> existence, for an alien situated in a very far away galaxy. The fact that >> >> this alien cannot detect us does not make the human disappearing. >> >> >> >> It is like the other side of the moon before we built rocket. >> >> >> >> It is like taking our theory at fave value, instead of eliminating some >> >> terms in the equation by sheer coquetry. >> > >> > Except in the case of quantum mechanics the theory you are saying predicts >> > other worlds, also predicts they are inaccessible. >> >> That is right, but the theory predicts that they are indirectly playing an >> important role without which QM explains nothing. >> >> No, the theory does not predict that these parallel worlds are playing an >> important role. The theory (QM) explicitly predicts that such other worlds >> are orthogonal to observation; they do not interact; and they are in >> principle inaccessible. They can, therefore, play no "important role without >> which QM explains nothing". I think you are very confused about how QM >> works, Bruce >> > The theory does not predict that the superposition plays an important role. > > That is not what I said. I said that parallel worlds do not play any > important role.
Without collapse, a parallel world is only a term in a superposition. “Parallel world” is the fancy name of superposition, or you can define world by using the interaction closure (and then they spread at the speed of light, or, like Deutsch, you consider them to be at the start, but that is “cheating”, as, a priori, we cannot know in advance which base will be used by the self-aware creature, so my favorite terming remains the relative state formulation. The word “world” is often accompanied by unwanted metaphysical assumptions. > > That is simply contradicted by the two slit experiments. No interaction does > not imply no statistical interference, or QM would not makes any sense at > all. Dirac considered the principle of superposition as the main quantum > feature. > > “Parallel world” is the same as superposition of state/histories. > > That is where the trouble lies. Your identification of any superposition as > a parallel world. There is a vast difference between superpositions and > parallel world, or "relative states" a la Everett. I don’t see any, except for that local “interaction closure” if we want introduce some nuance. > > Any quantum state can be described as a superposition of a set of basis > vectors in the corresponding Hilbert space. This basis set is not unique. In > fact, there are an infinity of possible sets of basis vector for any Hilbert > space. This is just a simple observation about vector spaces. No problem at all with this. That leads to different way to relativise the sates. > > When you start identifying this infinity of possible basis sets with possible > parallel worlds, then you get into big trouble understanding quantum > mechanics. Only if I add metaphysical assumption about the nature of those world. Let us avoid the term word, and talk only in term of relative states. Then what you say is just that being a superposition is relative to the choice of the base, and this means that I access to different states (superposed or not) according to what I decide to measure. > It has long appeared to me that you have suffered from this confusion. Maybe > that is the real basis of the fact that we can never agree on things about > elementary quantum mechanics………. I just try to understand you. I am not sure if we differ really, except you seem to put a lot of metaphysics in the notion of world. You know that with mechanism, there is 0 world. But an appearance of many histories. > > It is not a matter of the difference between collapse or no-collapse models > -- it is a matter of the basic interpretation of what Everett's "relative > states" actually are, and why the basis problem is so important for Everett. Everett makes clear that the choice of the base os irrelevant for the global description, and the choice of the base is done by the observer for the local description, exactly like with digital mechanism, where the notion of universal numbers play the role of the base. The whole theology and physics does not depend on the choice of the universal machinery we posit at the start, but from the points if view of each relative universal numbers, such difference play a key role in the local happenings and predictions. Bruno > > 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 [email protected] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/CAFxXSLSjKUw2WKLOCBsHr_2ML1PD3ZBu65poXVCLdMatM1wbRg%40mail.gmail.com > > <https://groups.google.com/d/msgid/everything-list/CAFxXSLSjKUw2WKLOCBsHr_2ML1PD3ZBu65poXVCLdMatM1wbRg%40mail.gmail.com?utm_medium=email&utm_source=footer>. -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/EF24C120-F9E7-47FA-920B-B678D5112496%40ulb.ac.be.
