tag:blogger.com,1999:blog-8148573551417578681.post6393996375665758746..comments2020-04-01T08:49:12.322-07:00Comments on Dark Buzz: Trying to prove many-worlds from first principlesRogerhttp://www.blogger.com/profile/03474078324293158376noreply@blogger.comBlogger12125tag:blogger.com,1999:blog-8148573551417578681.post-17353226705226713542020-03-12T10:06:24.689-07:002020-03-12T10:06:24.689-07:00A photon does not go thru two slits at once. A lig...A photon does not go thru two slits at once. A light wave goes thru both slits. If you put a detector at the slits, then it will only detect a photon in one of the slits.Rogerhttps://www.blogger.com/profile/03474078324293158376noreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-10198956394785727742020-03-12T09:53:05.769-07:002020-03-12T09:53:05.769-07:00Roger writes, "But to me, understanding it me...Roger writes, "But to me, understanding it means quantum mechanics is both local and non-classical."<br /><br />So you are saying that quantum mechanics has absolutely no nonlocal properties? How does a photon go through two slits at once?Golden Number Ratiohttps://www.blogger.com/profile/06047804495884984100noreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-32100368976028134572020-03-11T17:48:50.831-07:002020-03-11T17:48:50.831-07:00Wikipedia says "Superdeterminists do not reco...<a href="https://en.wikipedia.org/wiki/Superdeterminism" rel="nofollow">Wikipedia says</a> "Superdeterminists do not recognize the existence of genuine chances or possibilities anywhere in the cosmos."<br /><br />So I don't see any room for probability, free will, or anything like that. Everything is forced, from the beginning of the big bang.Rogerhttps://www.blogger.com/profile/03474078324293158376noreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-71876344599707403632020-03-11T12:21:46.511-07:002020-03-11T12:21:46.511-07:00Roger, going back 2 days: "Bell's theorem...Roger, going back 2 days: "Bell's theorem does not say anything about quantum mechanics" directly, but it implies that QM does not satisfy all the assumptions that Bell makes. It's enough (most clearly seen in L.J. Landau, Phys. Lett. A 120 (1987) 54, http://dx.doi.org/10.1016/0375-9601(87)90075-2) that the observables of QM that are used in models that violate Bell inequalities do not commute. Including noncommutativity into CM is one way to make violation of Bell inequalities possible.<br />[Noncommutativity and locality are intimately related because of microcausality, however: if operators do not commute, they must be associated with time-like separated regions of space-time.]<br /><br />Returning to today: Superdeterminism doesn't have to impinge on free will if it's understood to be about probabilities of actual events. Bell's arguments are all constructed from assumptions about probabilities. If a theory says that there's a half chance that I will choose cheese or ice cream after dinner, I still have that choice, it's just that in the past, it's been observed that I chose cheese half the time. Bell's idea of probability is extremely naive in its unstated assumption that probability "goes all the way down". I suggest that measure theory applied to random fields becomes mathematically delicate when there is a countably infinite or uncountable number of observables/beables, because one has to prove that either there is no implicit use whatsoever of the axiom of choice or that any use does not result in Banach-Tarski-type paradoxes. We can still use probability theory in careful formalisms, in particular if we follow rules similar to the Wightman axioms, however even operator-valued distributions are a little delicate.<br />All that means that although we and a Deity might be able to predict approximate probabilities for what happens in future, a Deity's perfect choice of noisy discontinuous initial conditions doesn't necessarily allow them to predict the future error-free. I take the lesson from this to be that we should construct models top-down, starting from observed statistics of experimental raw data, extrapolating from those to predictions, then collecting more observed statistics of experimental raw data, and repeat, ..., instead of trying to create models bottom-up, starting from dimensionless points. We do have the tools to do this, both quantum fields and classical random fields (both of which can be understood to be just indexed sets of random variables with different relative relationships between them.) Our theories, however, as effective quantum or random field theories, do not predict anything perfectly.<br /><br />Thank you for your comments.Peterhttps://www.blogger.com/profile/08654675777726560464noreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-62836482260096193802020-03-11T11:02:11.451-07:002020-03-11T11:02:11.451-07:00Ajit, yes, if you can suddenly change V everywhere... Ajit, yes, if you can suddenly change V everywhere, then you can have instantaneous action-at-a-distance. Relativity and quantum field theory are designed to explain how a field can get from one place to another.<br /><br />There never has been any experiment showing action-at-a-distance.<br /><br />Superdeterminism is a scheme to deny free will. If you believe in free will, then you won't have much interest in superdeterminism.Rogerhttps://www.blogger.com/profile/03474078324293158376noreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-20909796415085041862020-03-10T00:51:01.711-07:002020-03-10T00:51:01.711-07:00Many worlds isn't physics, just bad metaphysic...Many worlds isn't physics, just bad metaphysics dressed up in statistics. If you don't know how something works, inventing an infinite number of imaginary universes to hide your ignorance in isn't going to help you understand. <br /><br />When you are stuck in a hole, stop digging. CFTnoreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-82043047601177403222020-03-10T00:43:27.267-07:002020-03-10T00:43:27.267-07:00Oh, BTW, another thing.
The MWI (the Many-World I...Oh, BTW, another thing.<br /><br />The MWI (the Many-World Industries) would've made for a good joke ---if it weren't to be Government-sponsored.<br /><br />Best,<br />--Ajit<br />Ajit R. Jadhavhttps://ajitjadhav.wordpress.comnoreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-60873737140734820232020-03-10T00:15:32.415-07:002020-03-10T00:15:32.415-07:00Dear Roger,
You say: ``Local causality is axiomat...Dear Roger,<br /><br />You say: ``Local causality is axiomatic for all of science. ''<br /><br />I used to think so. But now I realize that QM (at least the non-relativistic Schrodinger's equation) has a part-global character. <br /><br />Each massive charged particle of e- or P+ always has the potential it sets up (for the other charged particles to ``feel'') anchored into its own *instantaneous* position. Simple statement, but apparently difficult to unpack for many philosophers of physics. <br /><br />In the non-rel. QM, the electrostatic potentials change instantaneously everywhere in the universe. So, there is a certain global character to it (aka instantaneous action at a distance, or IAD for short). So, it's a global theory, some one may say.<br /><br />However these same potentials also always remain anchored into the particle's current positions. So, no electrostatic potential field ever changes unless the particle positions change. Further, for e- and P+, the mass can be at least abstractly seen as being present ``at'' the potential-anchoring positions. So, there certainly is a local character to the potential fields.<br /><br />In the Schrodinger equation, there is nothing but V and \Psi which undergo changes.<br /><br />In the mainstream (textbook) QM, the \Psi field is completely determined by the potential fields. Hidden variables, therefore, must be seen as those variables that are in addition to these two. Schrodinger's equation successfully predicts all the known QM phenomena. (Even the non-relativistic one, within the regime of its applicability.)<br /><br />[In my new approach, there is a two-way interaction between \Psi and V, thereby introducing the nonlinearity necessary for solving the measurement problem, but without introducing a hidden variable.]<br /><br />In view of all these (and such) facts, QM cannot be completely characterized as being just local (as in collisions of balls in the Newtonian mechanics), or as just global (as in the Fourier theory, say of diffusion or waves). <br /><br />Philosophers first need to understand, absorb, and also hold in mind for all times, the above set of facts and observations. Unless and until they accomplish this part, they can't hope to make any consistent set of statements. <br /><br />To base arguments on an *implication* of the QM *axioms*, viz. Bell's *theorem* (and though enormously illuminating, it still is ``just'' a theorem), is not going to be very helpful in the absence of the understanding just stated.<br /><br />Best,<br />--Ajit<br />PS: I still don't know what to think of super-determinism. However, I cannot rule it out off-hand. Realize, super-determinism, even if valid, would pertain only to the *physical* aspects of the universe, not mental or spiritual. Free will would still exist---as a physically efficacious causal agent. It is not at all necessary to deny super-determinism just in order to save the free will. (Easy to see this point in the context of Newtonian mechanics. If you choose not to throw a ball, it doesn't trace the parabolic path.) <br />Ajit R. Jadhavhttps://ajitjadhav.wordpress.comnoreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-25307805107966141822020-03-09T21:34:51.553-07:002020-03-09T21:34:51.553-07:00Bell's theorem does not say anything about qua...Bell's theorem does not say anything about quantum mechanics. It only says something about classical mechanics theories.Rogerhttps://www.blogger.com/profile/03474078324293158376noreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-82629059805059116822020-03-09T19:39:04.563-07:002020-03-09T19:39:04.563-07:00My thing, I guess, is to pursue multiple perspecti...My thing, I guess, is to pursue multiple perspectives. Cherry-picking, for sure, I take license from Feynman, “The physicist needs a facility in looking at problems from several points of view.” So, yes, as I would put your final statement, QM/QFT is microcausal and noncommutative, but it is also natural to use the Poisson bracket to construct a noncommutative algebra of classical observables that is very close indeed to QM/QFT, as an alternative perspective. I find that understanding exactly how this extended CM is or is not the same as QM illuminates QM (as did Annals of Physics, I suppose.)<br />Understanding Bell's theorem in the context of only QM is in a way relatively straightforward: microcausality and noncommutativity more-or-less cuts it. Understanding Bell's theorem in the context of both QM and CM needs something more, for which one starting point that has not yet been developed enough is, I suggest, a common Hilbert space formalism for both.Peterhttps://www.blogger.com/profile/08654675777726560464noreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-3010035144857772892020-03-09T11:43:35.353-07:002020-03-09T11:43:35.353-07:00The Bell assumption that Maudlin calls "Bell-...The Bell assumption that Maudlin calls "Bell-local" is what others call a classical theory of local hidden variables. I guess I agree with Maudlin that we need to understand Bell's theorem, not weaken it. But to me, understanding it means quantum mechanics is both local and non-classical.Rogerhttps://www.blogger.com/profile/03474078324293158376noreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-20481989186195601792020-03-09T09:23:46.384-07:002020-03-09T09:23:46.384-07:00How do you feel about this: https://thequantumdail...How do you feel about this: https://thequantumdaily.com/2020/03/08/breaking-the-hold-of-bell-inequalities/. It's a little different from the usual, so I can imagine the unique Dark Buzz jumping either way.<br />You can consider an exchange I had yesterday with Tim Maudlin here: https://www.facebook.com/peter.w.morgan.98/posts/10223460635730528. I can imagine Dark Buzz having trenchant things to say about both sides of that.<br />I'm very curious whether I can sustain an interesting dialogue with Dark Buzz, which I've now followed by RSS for several years. It would be interesting to me, for sure, so the question is whether it might be interesting to you.Peterhttps://www.blogger.com/profile/08654675777726560464noreply@blogger.com