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  1. ttn

    children's books

    Check out the "frog and toad" books by Arnold Lobel. There are four different books that I know of, each with five or six short stories. They're fun and well-written in general, and a few of the stories (e.g., "the kite" from "days with frog and toad") have particularly good philosophical themes. We've also really enjoyed some of Robert McCloskey's books, especially "one morning in maine" and "blueberries for sal". Nothing particularly Objectivist or philosophical about these, but they're good stories with some nice science/nature-ish and pro-values themes, and they have a very calm, measured style that I find refreshing.
  2. Let's see... catching up... Thomas, there is no need for you to apologize to me. If anything, Lewis Little should apologize to you and others who got, from his writings, a very wrong impression about the state of contemporary thinking in the foundations of physics. Little works very hard to make it sound like he is the first person in the history of the universe to think that orthodox QM is a bad theory, that physicists' positivist and operationalist and anti-realist and anti-causal tendencies are unscientific and wrong, etc. Actually this kind of misinformation is a crucial part of his sales pitch. If people understood, for example, that Bohm (and to a much more significant degree, Bell) shared these sorts of reasonable motivations, they would first-handedly explore those other thinkers and find there the kind of serious scientific work that, well, makes TEW look like embarrassing crackpot nonsense by comparison. So, Thomas, I'm glad I helped you get unswindled. That's precisely the sort of thing I wanted to achieve by investing this time writing publicly about TEW. I hope others get a similar benefit from this thread. Then there's this historical question: It was Louis de Broglie who really first came up with the physical idea of waves somehow guiding the motion of associated particles. Actually, de Broglie came up with pretty much the whole "pilot wave" theory (i.e., what is sometimes today called Bohm's theory or Bohmian Mechanics) before the eventually-orthodox "quantum mechanics" was created by Heisenberg et al. For anyone really interested in the history here, probably the best source is "Quantum Theory at the Crossroads" by Valentini and Bacciogallupi, which I think is still forthcoming, but an earlier draft of the whole book is available for free on arxiv.org. Anyway, Schroedinger's contribution was "merely" to cook up a mathematical equation to describe the time-evolution of the waves de Broglie had already postulated. His physical interpretation was that |psi|^2 represented a mass or charge *density* for the electron. This is more or less still the picture that is taught to chemists... remember those pictures of fuzzed-out electron "clouds" surrounding atoms from your high school chem textbook? That was Schroedinger's theory. Of course, it is false, or at least very misleading. It was Max Born who introduced the now-standard "probability interpretation" of |psi|^2. I haven't studied the history here *really* carefully, but Born's writings have always struck me as seeming to presume a very good, de Broglie-ish understanding of the *meaning* of the probabilities -- that is, Born tends to speak of the probability of *finding* an electron at a certain place (with the implication that this is a mere passive revealing of a state of affairs that obtained prior to one's looking), as opposed to the eventual Copenhagen view that the looking itself causes the particle to (for the first time) acquire a definite location. That is, Born's own views don't seem to be as stupid as the views that are usually attributed to him in (e.g.) quantum physics textbooks. By the way, and just because someone made a remark that suggested some confusion about this, there is nothing whatsoever wrong with interpreting |psi|^2 as the probability for finding a particle. This is true according to both Copenhagen and Bohm. The rightness or wrongness is to be found in the underlying physical theory and the role that this probability plays in the theory. For example, in Copenhagen, psi is taken as a complete description of the physical state of the system, but it really is never clear if that means there is a real physical wave, or if psi is merely some kind of "complete description" of the *knowledge* a person can have about the system, or what. And probability enters by magic, i.e., as a special (actually contradictory) postulate about what happens when a "measurement" occurs. So the problem with Copenhagen is not the probability interpretation of psi, it's the ontological unclarity and the "unprofessional vagueness and ambiguity" created by the tension between the two different sorts of laws pertaining to "measurement" and "non-measurement" situations (whatever those are supposed to mean exactly). By contrast, in Bohm's theory, psi is a real physical wave, which guides the trajectory of real physical particles according to a clean and clear mathematical law which applies all the time no matter if someone is "measuring" something or not. And it turns out that the probability of finding a particle in a particular spot is proportional to the intensity |psi|^2 of the wave at that spot. What possible basis could there be for complaining about that? Maybe that clarifies something for someone. Let's see. I also wanted to respond to another bit of ridiculousness I saw on the speichers' site. PhilO there recommended Joy Christian's recent papers purporting to have refuted Bell's theorem. This just proves that PhilO is merely an ignorant partisan in this debate. His recommendation is equivalent, say, to some unthinking person hostile to Objectivism (and who has never seriously studied any philosophy) casually recommending the recent "refutations" of Rand on the Maverick Philosopher website. I suppose I should actually say something about what's wrong with Joy Christian's "refutation" of Bell, else I will be accused of flinging empty ad hominem. OK, fine. His whole paper is based on the *stupid* idea of making the A's and B's (from my derivation of Bell's theorem in the book review which began this thread) into non-commuting numbers. Thus, he contemplates theories which predict that, for a given physical state of the particle pair and given orientations of the two polarizers, Alice's photon will yield outcome "A" and Bob's photon will yield outcome "B" -- but where "A times B" is not necessarily equal to "B times A". Now if you for one second take your head out of Plato's heaven and remember what these symbols A and B are supposed to mean, you realize that this is completely stupid. The whole thing is a brilliant example of what's wrong with so much of theoretical physics today. It's impeccable and sophisticated mathematics that makes perfect sense so long as you completely and totally forget that you are supposed to be doing *physics*, which requires that you remember *what you are talking about*. Anyway, in the paper Joy Christian does a nice little algebraic dance with these non-commuting numbers, and shows that the correlations (which remember are calculated precisely by multiplying the A's by the B's and then averaging over various things) can exceed the limit expressed by Bell's inequality, and in particular can agree with the experiments. So it is supposed to be a counterexample to Bell -- a locally causal theory which nevertheless makes predictions consistent with the experiments. It is no such thing, because the theory's *actual* predictions for the experiments are not even wrong -- which I actually mean here in its literal, as opposed to rhetorical, sense. A wrong prediction would be one that says a given particle goes up when in fact it goes down, i.e., that says A = +1 when actually A = -1. That's a wrong prediction. What kind of prediction do you have if your theory says that the value of A (which remember denotes whether a certain particle goes up or down) isn't *either* of +1 or -1, but is instead some kind of mathematical operator which fails to commute with other similar operators? Such a "prediction" does not rise to the level of achieving a wrong prediction. The lesson here is that if you want to actually make a useful contribution to discussions on these issues, you have to do a little more than spend 5 seconds googling for "Bell theorem refutation" (or however PhilO found this paper) and then posing like you understand the issues and have read the relevant literature. There's a name for people who do only that: frauds. To save PhilO some of his valuable time in future rounds of the debate, here are some other completely stupid things he could google up and cite to his fellow ignorant crackpot-supporting friends as bolstering their position: the infamous Hess/Phillipp "refutation" of Bell's theorem, Ghose's various (proposed) experimental "refutations" of Bohmian Mechanics, Bohr's "refutation" of the EPR argument, etc. Since this thread seems to be dying down (which I do not consider a bad thing), let me also underscore some of the high points of the discussion so far. 1. Three or four times in the past, Little has put forth detailed attempts to predict, using TEW, the correct predictions for the EPR-Bell type experiments. Each of these specific proposals has been retracted (sometimes amid great rhetorical displays of dishonesty). In his new book, Little simply dodges the whole issue, presenting a bunch of misguided polemics against Bell and Bohm, and *not* presenting any actual demonstration or calculation to back up his (empty and false) claim that TEW can correctly account for the results of these experiments. It can't. If it really could, Little would have shown us how. This is not the case of a theory which "has yet to address" a certain point. It is a case of outright fraud and evasion. Think I'm wrong? Then you can win a thousand of my dollars. 2. We can be certain, even without knowing anything about TEW other than that relativistic local causality is one of its foundation stones, that TEW is false. Bell's theorem and the results of the relevant experiments prove that no such locally causal theory can make the right predictions for these experiments. Any proponent of TEW who wants to be taken seriously by serious people must first acquire and then display a genuine understanding of Bell's work. Lewis Little should lead by example here. Of course, anybody who did acquire that understanding would then necessarily cease to be a proponent of TEW. 3. In probably my most important post in this thread, I explained in some detail how TEW in fact cannot even account for the results of the two-slit experiment (which TEW's advocates, including Little, universally take as the most clear-cut and most dramatic evidence in favor of the theory). This deserves a serious response from anyone who wants to maintain that TEW deserves even a moment's further consideration. One of the innocent young things who posts to the speichers' site should raise this question there and see what kind of response follows from the theory's last-remaining supporters. 4. People need to understand that, even leaving aside for the moment the question of TEW's truth, Lewis Little as a "commentator" on foundational issues in physics, simply cannot be trusted. He badly misunderstands (really, just fails to even approach proper understanding) and/or deliberately distorts Bell's work. Same for Bohm's theory. And same for the orthodox/Copenhagen views. If you think Lewis Little is some kind of original or important thinker because he had the courage and intelligence ("north of 200"!!) to stand up to the corrupt physics establishment, you simply need to grow up and get out more. Every crackpot in the history of the universe has tried to create precisely this same impression, and typically succeeds in fooling a few foolish people. Don't be foolish, people, and don't get fooled. Especially when you are wearing your Objectivist hat. 5. Being ignorant about a given field is OK. But being ignorant *and nevertheless supporting embarrassing crackpot garbage from a field of which you are ignorant, and doing so qua Objectivist* is not OK. If a self-proclaimed Objectivist got interested in astrology, or the magical healing power of crystals, or intelligent design, and started talking about their wonderful "alternative to scientific orthodoxy" on Objectivist websites, listing the crackpot originators of such theories as "experts" on forums for ayn rand fans, linking to stupid refutations of darwin, etc., the appropriate response of sensible Objectivists would *clearly* be to SHUN and REPUDIATE these people. This is what should happen to TEW supporters.
  3. By "EPR-Bell type experiments" I just mean the experiments of Aspect, Weihs, and the other similar ones that are specifically designed to test Bell's inequality. So there must be some sort of confusion here (perhaps my fault) if you thought I was referring to something *other* than Aspect's experiment here. Hopefully all is clear now. It's certainly true that the fact that relativistic local causality (i.e., "locality") is refuted by these experiments is an important and surprising discovery. Most physicists are still in denial about it, which I guess puts the TEW crowd (for once) in good company.
  4. Don't confuse confusion with the desire not to know. But, since it's so simple, here you go. By "non-locality" I mean (unless the context specifically indicates otherwise): faster-than-light causation, of the sort ordinarily thought to be prohibited by relativity. Perhapsa further comment I made on HBL last night would be worth adding: "the whole idea of instantaneous action-at-a-distance is a complete red herring -- it should *never* have been in play in these discussions at all. That it has been (and [...] continues to be) is only a result of obfuscation and misinformation on the part of TEW's supporters. Whether the misinformation campaign is deliberate, or merely based on ignorance, is irrelevant. If one is ignorant enough of the technical details to be able to innocently proffer that kind of misinformation, one shouldn't proffer it. And of course nor should one do so if one knows better. Given that there is such misinformation in play, people watching from the sidelines and trying to decide whom to believe need to be extremely cautious. There is such a thing as a sensible-sounding argument whose (perhaps tacit) premises are total fabrications and distortions of the truth." I hope that clarifies. Though I can guarantee you that certain dishonest individuals will, no matter how many times this is explained to them, continue to insist that what I really mean by "non-locality" is ... something other than what I do mean. Such people are not interested in the truth and, after a point, can no longer be dealt with rationally.
  5. I'm not sure exactly what you're asking. Are you asking why I didn't appeal to Aspect, but instead appealed to the more recent Aspect-like experiment done by Weihs et al in Innsbruck in 1998? If that's it, there's no real reason or answer. The later experiment is just better, though in ways that probably don't matter for the level of the discussion here. Appealing to Aspect instead would have been equivalent. Or did you mean: why didn't I appeal to experiments (like Aspect's) at all? If that's it, I think the answer is: I thought I did. It's certainly a crucial piece of the puzzle. The way we know that faster-than-light causation exists is precisely from the Aspect (and other similar) experiment(s), interpreted using Bell's theorem. Well, multiple types of non-locality maybe. The two that were in play in this discussion were the following. The first type was the sort of "nonlocal state description" that one has explicitly in QM, in which (for example) two spatially-separated entities (like the two photons in an EPR-Bell experiment) fail to have individual distinct polarization states, but are instead part of a sort of holistic, joint 2-particle polarization state. Then the second type of non-locality is the non-local *causation* shown to exist by Bell's theorem and the associated experiments. Note that there isn't really any *causation* involved in the first type of non-locality. So the point I was making was that one directly practical reason Bell probably formulated the theorem the way he did (and this is in addition to the fact that it makes the theorem *stronger*, which other things equal is obviously a good thing) was to be able to show clearly that the nonlocality proved by the theorem is *not* the (familiar, subtle) sort that is manifest in QM (and not in any *obvious* way in conflict with relativity theory), but is instead a more blatant non-local *causation* which *is* obviously in conflict with relativity theory -- or at least with what everybody took to be an implication of relativity theory all those decades. Hope that clarifies. If not, it's probably not worth pursuing. It was really only a pointless speculation about why Bell presented something one way rather than a slightly weaker, but maybe more physically transparent, other possible way. Sure. I won't be reading and posting as much as last week, but I'd be happy to answer any of your follow-ups about this stuff.
  6. Thomas, we're going in circles, so after this post I won't discuss it any further. Your point seems to be that it's a logical fallacy to infer from "Mr. X is an Objectivist" and "Mr. X believes special-scientific theory Y" to "Y is part of or endorsed by Objectivism." That's of course true. But don't you agree that it's nevertheless reasonable for some honest person to form a negative judgment of Objectivism if he sees someone (who loudly proclaims himself an Objectivist) endorsing and proselytizing for a bunch of dishonest crackpot garbage (and worse, doing so at least in part on nominally Objectivist grounds, e.g., by citing Ayn Rand's statements about causality)? People do, and should do, this kind of thing all the time. It comes down to what I said before: it is not unreasonable to assume that a person's actual cognitive functioning reflects his explicitly endorsed epistemological beliefs. So if a person claims to be an Objectivist, but can't tell the difference between good science and pseudo-science (e.g., say, they are into astrology and the magical healing power of crystals), rational observers will be inclined to infer, validly if wrongly, that Objectivism itself is pseudo-scientific. You keep mentioning Rand's alleged agnosticism about the theory of evolution. (I'm not really sure where this claim comes from, hence "alleged.") But there's an important difference between *not* taking a position on some scientific issue because one doesn't have the expertise to take such a position (which is what AR supposedly did), and *taking* a position *despite not having* the relevant expertise. I think I have made it clear from the very beginning that the people I mean to criticize are those who are ignorant of physics, but nevertheless respond to the superficially-Objectivish-sounding sloganry in Lewis Little's writings by forming a favorable judgment of TEW as a scientific theory. People who are ignorant of physics and know it and so refrain from forming a favorable judgment of TEW (or Bohm's theory or any other theory) will catch no flack from me. You wrote: "If you want to get to the epistemological method of TEW and show that this is wrong, and that it could not have come from a rational approach to science, then that is a different (though related) point." That is precisely what I have been showing. You wrote: I'm sorry, but this is just the same old false dichotomy. Yes, physics is not deduced from philosophy. We all get that. Neither is, say, the question of whether the alignment of the stars and planets has a causal influence on human activities. But does that mean that if some crackpot astrologer gains a following among some self-described Objectivists, we should all just turn the other cheek and say "well, if anyone forms a negative judgment of Objectivism based on this, it's their problem, not ours, since astrology isn't part of philosophy and they should know that." Clearly not. The right response is to repudiate the crackpot and his followers and ask them to please take their crazy pseudo-scientific nonsense as far away from Objectivism as possible. You wrote: "I don't know enough to reject TEW". Don't confuse "rejection" with "lack of endorsement." Actually, this is an example of an important point in Objectivism, namely, that there isn't a symmetry between the positive and negative. (Knowledge is not the same as a lack of ignorance, you don't build by refraining from demolishing, etc.) If you don't know enough about physics or TEW to have a positive position one way or the other on any of the relevant options, it is OK to simply not have a positive position. Don't endorse TEW, don't endorse Bohm's theory, don't endorse my/Bell's interpretation of Bell's theorem, etc. That, ultimately, is all I'm asking of anyone. I'm *not* asking anyone to take my negative judgment of TEW (involving, as it does, certain advanced technical things like Bell's theorem) on faith. (Though I have to also say that there is plenty of evidence, available to any honest non-expert, that Little is a dishonest crank, so you don't actually need to understand fully how to prove that TEW is false, to know that it and its author and supporters are embarrassments to and dangers to Objectivism.) All I'm asking is that people who don't know enough physics to (say) answer the many objections I've raised, be honest with themselves, and refrain from endorsing and proselytizing for TEW, especially under the banner of Objectivism.
  7. I'm no dummy, but that's all way too complicated for me! Much easier to just type out l-a-m-b-d-a. I will also say: thank god for latex!
  8. On a different site, SoftwareNerd wrote: SN, you are making a good point on that other site, namely, that the TEW supporters do, in fact, explicitly base their support for TEW on Objectivism. But your claim here about what I am saying "at the core" isn't right. I mean, I certainly agree that anyone who is convinced (favorably) about TEW, shouldn't misrepresent Objectivism by saying that TEW is uniquely consistent with Objectivism metaphysics (which claim is simply preposterous). But *at the core* what I'm saying is this: if you're convinced (favorably) about TEW, you are an ignorant fool who has been swindled by a crackpot. And any perceived affiliation between such people (both the swindler and the swindlees) and Objectivism can only hurt Objectivism.
  9. Let's see... Thomas suggested that I'm calling TEW "aribtrary (less than wrong)". I never said that and don't think that. In terms strictly of its truth/falsity, TEW is false. What makes it worse than false is the evasive and dishonest character of its advocates' advocacy of it. But it is not arbitrary (in the technical Objectivist sense). It is not so much put forward in defiance of the need for evidence (and so ultimately meaningless), it is rather put forward in defiance of the fact that it contradicts known evidence and in massively negligent defiance of the proper methods for generating and attempting to validate scientific theories. (That's the "crackpot" point.) Thomas, in your other comments, I still detect a confused and invalid desire to ask, about any proposed new existent in physics, "but what's it made of?" or something to that effect. I think you could, with equal legitimacy, ask the same questions you are asking about (e.g.) "real waves being involved in QM" (and that you were asking about gravitational fields on the other thread), about atoms or electric/magnetic fields in the late 19th century, or about electrons around 1900, or about neutrinos and the host of other particles discovered since then, or about dark matter today, etc. For all of these I would ask you: what kind of answer are you looking for? The whole point of proposing new entities in theoretical physics is that they aren't made out of anything like the stuff known about previously -- else they wouldn't be "new". Now, maybe sometimes some future context of knowledge will allow an answer to that kind of question -- as, for example, it turns out atoms are made out of electrons, protons, and neutrons. But there is no basis for thinking that electric fields are "made of" some more elementary objects. So there is simply no answer to that kind of question. But I don't think further discussion of this is going to go anywhere useful, so take the last word if you want it on this. Regarding "the moon is made of green cheese" and the associated discussion of the relation of physics to philosophy, there is a false dichotomy being presented. It is not true that "physics has nothing to do with philosophy", but nor, as Thomas pointed out, is it true that physics is simply deduced from metaphysics. But there is a third alternative -- which is the truth -- namely, one *uses* (and hence *displays*) a certain epistemological approach in arriving at ideas in physics (just as in any other field). So if one claims to be an Objectivist, and/or is supported by self-proclaimed Objectivists, and/or is listed as a physics "expert" on websites (literally) under the banner of Ayn Rand, etc., reasonable people out in the world would be perfectly justified in assuming that the epistemological approach to ideas one displays are somehow expressive of Objectivism. And so if the "one" in question here is in fact a complete crackpot, including all of the aspects I listed in my book review, it reflects *very poorly* on Objectivism. This doesn't seem like a really tricky point to me. Thomas wrote that "that part of [my] thesis is overblown" -- meaning the part about my thinking TEW is an embarrassment to and danger to Objectivism. His grounds for this was a reference to the Maverick Philosopher, who thinks Objectivists are kooks on some grounds having nothing to do with scientific claims. I just don't get that argument at all. Yes, there are some dishonest or otherwise hopeless people who think Objectivists are kooks. But there are also lots of honest and sensible people (including, say, your average physics professor) who have no real opinion one way or the other about Objectivism. These are the people that matter, and they are the ones whose opinion may be *rationally* swayed *against taking Objectivism seriously* if they find it to be associated with something like TEW that they are in a position to recognize for the dishonest crackpot garbage that it is. Again, not a really tricky point.
  10. Grames, thanks, these are all very good questions/points. That's the whole essence of the theory, so yes -- but not just "at one time". Still. That's right. Actually maybe it's worth amplifying for people who don't know the history. Aspect's experiment was in 1982. In the decade or two prior to that, there had been a number of tests of the correlations that are supposed to be restricted by Bell's "locality inequality". But all of these tests used static polarizers, and so (as everyone recognized all along) it would have been possible to account for the results in a locally causal way by positing some kind of influence propagating (at or slower than the speed of light) from the polarizer on one side, to the particle/polarizer/detector on the far side. That is, if the polarizers are just sitting there in place, then there is no real argument from relativity's prohibition on superluminal causation to the premise of Bell's theorem you describe below (namely, that the outcome on one side shouldn't depend on the setting, the orientation of the apparatus, on the other side). This maybe clarifies the way in which it is disingenuous for TEW supporters to say things like "well, there's just this one experiment that Little hasn't yet figured out how to account for". The truth is that this experiment -- and then the much cleaner and better version of the same thing that Weihs et al did in 1998 -- was done *precisely* to rule out the possibility of a broad class of theories of which TEW is one example. And the results of these experiments are pretty unambiguous. That's right. The lambda (not sure how you managed to produce the symbol here??!!) refers to some kind of "complete state description" for the pair of particles. Let me say that again in a different way because it's important: lambda provides a description of the *pair* of particles, jointly, i.e., the pair treated as a unit. Now, I'm not entirely sure I understand what's bothering you, so correct me if this is wrong, but I *think* your question is: doesn't this allow a certain subtle sort of non-locality and hence weaken the claim that all of this is being derived from the premise of local causality? If that's right, you're absolutely right. Bell's presentation here actually permits (say) the outcome on one side (M, or more precisely the probabilities for different possible outcomes M, since Bell is here not assuming determinism) to depend on the instantaneous state, not only of the particle that's getting measured there, but also, in principle, on the state of the distant particle. And there's indeed no locally causal way in which such dependence could be explained -- the distant particle being, after all, distant. So if, for example, you have a theory in which the states of the individual particles (say) changes randomly after they leave the source, such that the state of one particle would not necessarily allow you to infer with certainty the state of the other particle, you could sneak some nonlocality into the theory and it would *still* respect the correlation limit expressed in Bell's inequality. But let's be very clear about what that means. It means that any theory which *fails* to respect that limit, i.e., any theory which predicts violations of Bell's inequality, has to be *really* non-local. That is, this subtle weakening of the premise actually strengthens the overall argument. Of course, as you raise below, we can already at this stage of the argument assume determinism if we want, because we can already infer that separately, from local causality, using the EPR argument. So this point is really somewhat moot. I think Bell did it this way because the relevant state description *in orthodox quantum theory* is not "separable", i.e., you can't reduce it to "the one particle is in the state such-and-such, and the other particle is in the state so-and-so". Rather, it's irreducibly of the form: "both particles jointly are in the state such-and-such." That's admittedly weird and hard to understand. But, for Bell's purposes, everything is much clearer and better if you simply leave that aside and focus on the more radical sort of non-local causation that violation of his inequality entails. And plus, this way, there is an unambiguous (though not uncontroversial) argument that orthodox quantum theory itself already displays the problematic sort of non-local causation (in addition to the sort I think you are raising a question about here). No, definitely not. The argument was that, in the special case where the two experimenters measure along the same axis, it's an experimental fact that the outcomes on the two sides are always perfectly correlated. And, say EPR and also Bell, the *only* way to account for this correlation -- *if* you don't allow the possibility of nonlocal causation -- is that the outcomes were determined all along and somehow encoded into each particle separately at the source. But if you *do* allow the possibility of nonlocal causation, then you could have a model like this: neither particle is determined to produce either particular outcome for any of the possible measurements you could make on it -- but then one of the particles gets measured, is forced to "make an arbitrary, non-pre-determined "decision" about which outcome to produce, and (say) calls the other, distant, not-yet-measured particle on a little tiny faster-than-light cell phone to tell it which outcome it decided to produce. Then, should the other particle be measured along the same axis, it will "know" how to answer so as to guarantee the perfect correlations. The point is, such a model is explicitly nonlocal and explicitly non-deterministic. Yet it produces the right correlations for this special class of experiment. So clearly you're not going to be able to infer determinism from these correlations if you allow nonlocal causality. Make sense?
  11. I'll try to answer your questions, Thomas, but for the record: no, that isn't what we're talking about, if what you mean is that a positive assessment of Bohm's theory is somehow part of the argument for the worse-than-false status of TEW. You can know with absolutely certainty that TEW is wrong and that Lewis Little is a crackpot without knowing *anything* about Bohm's theory. The only relevance of Bohm's theory to this conclusion is that Little's book contains a number of very deceptive polemics against Bohm's theory, so understanding something of the truth on that point adds a little bit of evidence in support of the claim that he is, at best, negligently ignorant of what he's writing about. OK? Your main question about Bohm's theory seems to be: where do the waves come from? You are correct that there's not really any answer to this question in the theory. Probably the best way to think about what the theory says on this point is this: the waves have always been there, accompanying the particles. So, for example, a device that emits particles dosn't *produce* a new wave for that particle ex nihilo, nor is the wave "emitted" by the particle as it travels. Rather, that particles has always had some kind of accompanying wave, and what the particle emmitter does is to somehow reconfigure the structure of the wave. The main point, though, is that your question isn't a *necessary* one in the contemporary context of knowledge. It's just the same as your question about Newton's theory of gravity. There is no need whatever to answer this kind of question before believing in the theory. (I'm not saying anyone *should* necessarily believe in it, just that such belief can be fully justified without having any particular answer to the question of "where the waves came from originally".) A parallel here might be: you can rationally believe that the theory of evolution by natural selection is true, and even have certainty on that point, without having any answer to: "But how did life get started originally?" It's not that it's an invalid question, it's just not one that necessarily arises as part of the answer to: "By what mechanism did man and other species evolve into their current identities?" So maybe in 10 or 100 or 1000 years, once we figure out (say) exactly what's happening in the double slit experiment, then some future generation of theories will address something like your question in some way. Or maybe not. The point is just that, now, that kind of question is no kind of valid objection to the theory, nor even a proper basis for "concern" about it. You also said there's no equation in Bohm's theory for the "force" exerted on the particle by the wave. The equation you seek is right there in section 4 of the article ("the guidance equation"). This is an equation for how the *velocity* of the particle depends on the structure of the wave. This is the cleanest and most revealing way of defining the theory mathematically. But if, for some reason, you insist on couching the theory in Newtonian terms, you are free to take the time derivative of this equation (to get the *acceleration*) and then multiply by the particle's mass to get the literal *force* exerted on the particle by the wave. Turns out you can write it as minus the gradient of something, which is nice, because then that "something" can be interpreted as an extra, purely quantum contribution to the particle's potential energy field. This is how Bohm himself originally formulated the theory. (See section 5 of the article for more on the "quantum potential".)
  12. First, some quickies... Grames: good for you! It's probably my all-time favorite physics paper. I mean, even just the first sentence is completely brilliant and hilarious. I hope you enjoy it, and I would be delighted to help if there's anything in there you get stuck on, or want a different formulation of, or don't think is right, or whatever. AisA: There are lots of schematic pictures of this sort of experiment online. I just googled "EPR Bell experiment" and found a wikipedia page with a semi-acceptable (but highly schematic) diagram: see here. I'm sure if you spend just a minute and look at other hits, you'll find something better. You can also check out the actual paper by Gregor Weihs, et al, who did the infamous Innsbruck experiment. (By the way, nobody but people on one side or the other of the TEW debate calls the experiment that. Same with "double delayed choice.") The paper is too technical to follow all the details of unless you are trained in physics, but there's another good schematic diagram, and some pretty careful description of the real details. softwareNerd: thanks for clarifying the ground-rules about the content of the thread (viz., no meta-discussion and no off-topic discussion of other theories). Hopefully the following quick remarks won't violate the rules. (If they do, you have my blessing to just delete them.) A reader wrote me privately and made a good point: a lot of people here seem to misunderstand the concept of "ad hominem." This is properly understood as a logical fallacy, i.e., as a kind of argument that isn't valid because it substitutes or sneaks in a personal attack where a genuine premise should be. But what I said about "altonhare" was simply not in this category. And neither is anything I have said about Lewis Little. And neither, by the way, is a statement like "Kant was not only wrong, but evil, because..." The point is, it isn't the fallacy of ad hominem merely to criticize someone. If you say "he's wrong because he's a jerk" that's an ad hominem fallacy. But if you say "he's a jerk, because he tripped me and spit on me" that is just a regular old valid argument which has, as its *conclusion*, a statement about someone's character. Maybe that will be helpful to some people in trying to understand and assess all these claims that I'm attacking the person instead of discussing the physics, etc. Let me finally stress something that I probably should have clarified better earlier on. If TEW was merely a wrong theory, it of course wouldn't deserve the things I've said about it or its supporters. Nor would it be any kind of danger or embarrassment to Objectivism. But my whole thesis is that TEW is *worse* than "merely wrong". It is, for someone with the relevant background knowledge, *obviously* wrong, *obviously* unprofessional and unserious, and its supporters have repeatedly engaged in dishonesty and evasion. That's why I described the theory as "dishonest crackpot garbage" as opposed to, say, "false." I am saying all of this now just to further clarify why I introduced terms like "crackpot" and "dishonest" into the discussion from the very beginning (and thereby unwittingly brought about the flood of meta-discussion). It's because these things are an *essential part* of the conclusion I am arguing for -- TEW should be shunned, not because it is false, but because it is dishonest crackpot garbage. Hopefully that clarification isn't out of bounds. Now finally let me say something about this essay Olex linked to: Actually I think this is, at best, highly misleading. I mean in particular the part around "figure 3" where Mr. Speicher tries to argue that there is strong evidence for the basic TEW "reverse waves" hypothesis in the fact that an interference pattern is still observed even if the detection screen is moved forward or backward. This is actually complete hogwash. Maybe it would be good to pause here and allow interested readers a minute to contemplate what massive tacit premise is smuggled into the argument. . . . . . Seriously, take a minute and think about it. . . . . . . . Got it yet? . . . . . . If this were a class, I would actually wait in silence until you volunteered something. But, OK, fine, I'll just tell you. . . . . . Here's what I have in mind. The whole discussion just assumes that *particles move in straight lines* (except where they don't, e.g., at the slits). But if you drop that assumption, then there is *no grounds at all* for inferring, from the fact that the interference pattern is preserved when you move the screen, that the screen is somehow causally operative in determining the trajectories of the particles. See, for example, the figure about halfway down the page on this article about Bohm's theory. What's plotted are simply a bunch of representative trajectories for the 2-slit experiment, as predicted by Bohm's theory. Note that they aren't straight lines, and so (I think obviously, looking at the picture) you're going to get a nice interference pattern no matter where you put the screen. (According to Bohm's theory, a particle just makes a flash/spot wherever it in fact hits the screen.) Actually, the situation for this pro-TEW argument is even somewhat worse than merely that there's no evidence supporting the claim that the particles go in straight lines. There's I think a problematic inconsistency in the theory here. For, according to the theory itself, the particle trajectories *do bend* at the slits. That of course would be fine if there was, in the theory, some clear account of why that happens there and not elsewhere. And of course, if TEW were really a serious and clearly-formulated theory, there'd be no question here -- we'd just go look at the paper or book or whatever where the theory is presented and this kind of question would be addressed. But in fact this is the kind of thing that isn't actually addressed, which is why I say TEW isn't a serious and clearly-formulated theory. Anyway, my point is that it seems like there really is an inconsistency here for the theory -- what, after all, is a "slit"? It's a place where there is... nothing. I mean, if the idea was supposed to be that the trajectories bend at the location of some blob of physical stuff, that would be perfectly plausible, because the waves could scatter off of the stuff or whatever. But there's no blob of stuff at a slit. A slit is precisely where the blob of stuff isn't. That is, what's there at the slit (where according to TEW the waves all scatter and the trajectories all bend) is precisely the same as what's there at any other random location behind or in front of the slits -- namely nothing (meaning, you know, stray air molecules, or whatever electromagnetic fields and whatnot are present in the "vacuum", etc.). But if this nothing can so effectively scatter waves and hence bend trajectories at the slits, why can't it do it at other locations in front of or behind the slits? And if you follow that, you see why it's then inconsistent to have assumed at the beginning that (other than at the slits) the trajectories have to be straight lines. In fact, it's even a little worse than that, because if the waves can scatter off of the "nothing" that's (say) behind (from the point of view of the reverse waves, i.e., in front of vis a vis the motion of the particles) the slits, then the whole claim that the waves emitted by (say) a point right in the middle of the detector will interfere constructively at the particle source, totally falls apart. Because now there won't just be these two constructively interfering paths, there will be infinitely more possible routes from that point on the screen back to the source (e.g., paths made of two straight line segments, but with the "vertex" at some other point in front of or behind the slits, and then also paths made of 3, 4, 5, ... straight line paths) and the net effect will be no particular simple pattern of interference at all. The whole alleged "explanation" of the double slit experiment falls apart. Or maybe it doesn't fall apart. Who knows. The point is, there's just no way to know because the theory is just a half-baked idea rather than a definite and clearly-formulated proposal. This is the kind of question that, if posed to Little or some pseudo-knowledgeable proponent of TEW, would result in new and ad hoc additions to the theory, which would in turn raise further questions and risk further inconsistency. And since (as I think I indicated in an earlier post in response to something Thomas had said) questions *just like this* proliferate in all directions as soon as you try to figure out how/whether this theory actually works, it's just not worth pursuing any of them. Especially when the EPR-Bell stuff so clearly and unambiguously rules out the relativistic local causality that Little has defined as a fundamental pillar of the theory.
  13. That's definitely on the right track. Most physicists wouldn't really consider the issue of whether or not it's "surprising" to be scientifically meaningful. They'd say: quantum mechanics just predicts that, for plane polarized light incident on a polarizer at a certain orientation, there's a certain probability for it to pass and a certain probability for it to get absorbed. What more could one want? Of course, one can and should want more -- ultimately. But it's also valid to knowingly postpone questions about "what's really going on" or "how to visualize it" until some future date at which there will be some actual evidence on which to base answers to those questions. So, I'm not in favor of "shut up and calculate" as a philosophy or a mantra, the way many physicists seem to be, but it is sometimes the perfectly reasonable thing to do. I will also mention that in *classical* E&M, we don't have photons (i.e., individual "particles" of light) at all -- just electromagnetic waves. And what that theory says is that a polarized plane wave incident on a polarizer will be *partially* absorbed and *partially* reflected. (More precisely: the component that is parallel to the polarizer's axis will be transmitted, and the component that is perpindicular will be absorbed.) And in a sense this gives the same math that one has at the photon-level in the quantum theory of the same phenomenon: the quantum mechanical *probability* for a single photon to be absorbed, is identical to the *fraction* of the wave's intensity or energy that gets absorbed according to the classical theory. This correspondence between the numbers probably counts as some kind of rough way of "understanding" the QM formulas, and would be cited as such by most physicists. Of course, to really understand what's going on causally, you'd need a consistently causal version of quantum theory. But this is at least something. For what it's worth, I also find Mr. Speicher's "pencil" analogy to be more confusing than illuminating, for precisely the reason you bring up. That's basically right. I think part of what you had in mind here (but didn't quite say explicitly) is that Bell's theorem is not in any way based on some particular proposed candidate "story" or "theory" about how it works, how it should be visualized, etc. Bell's theorem actually doesn't have any specifically physics-related premises at all, beyond the assumption of relativistic local causality -- which is just the assumption that, *however* this actually works down at the micro-level, the outcome of the experiment over here shouldn't depend on how the experimenter over there chooses to orient her polarizer, and vice versa. Which means you don't actually have to know "how to visualize" what happens when a photon passes or fails to pass a polarizer, in order to *completely* understand Bell's theorem. Does that help?
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