Electrons travel faster than the speed of light

[muppet]

Maanelli: Reilly's central point is that orthodox QM has given us a tool of astonishing predictive power, and if BM is going to be taken seriously then it has to be able to replicate that. Before anyone invests much effort in acheiving mastery of the Bohmian formulation, they want to see evidence that it can reproduce calculations such as those Reilly cited.
Reading http://arxiv.org/PS_cache/quant-ph/pdf/0611/0611032v1.pdf I quote:

... Agreed, all these models have a "cooked up" flavor, but this is due to the fact that their task is (in general) to reproduce the predictions of existing theories. These exising theories work FAPP (for all practical purposes) and the ambition of Bohm-like formulations is not to extend their predictive powe but to put them on a conceptually firm basis.

This was taken from the conclusion of the link you provided. Most of the discussion on relativistic variations in that paper was about what constituted a Bohm-like interpretation. If the state of BM is really as advanced as you claim, that doesn't seem like the most salient point to be discussing. The thing I found most striking in both that document and in http://www.iqc.ca/~qipcourse/interpret/lectures/lec-09-10-dBB.pdf
is the problem of quantum equilibrium. As far as I can see, even non-relativistic BM cannot claim to be substantially conceptually superior to orthodox QM until that question is resolved satisfactorily. It may just be because of the imperfect english in which the second is written, but it looks to me like the probabilities in BM currently just piggy-back the successes of othodoxy. In any event, conceptual coherence is not enough for a theory to become accepted; it needs to explain the experimental facts. It might do this better than classical mechanics, but when current research is into QFT, explaining the two-slit experiment is not enough. Additionally, the impression those links give me is that a great deal of BM research involves coercing it in such a way that it can borrow successes from the orthodox approach. This doesn't drive science forward, and until a coherent picture emerges of the role of probability in the theory (apart from loose language about it being epistemic rather than ontological) it doesn't even give us a physically interesting picture.
Don't get me wrong. I think the central idea is an extremely interesting one. But until it's substantially more sophisticated and conceptually robust, it cannot be championed in anything other than a tentative way.

 

[Maaneli]

Maanelli: Reilly's central point is that orthodox QM has given us a tool of astonishing predictive power, and if BM is going to be taken seriously then it has to be able to replicate that. Before anyone invests much effort in acheiving mastery of the Bohmian formulation, they want to see evidence that it can reproduce calculations such as those Reilly cited.
Reading http://arxiv.org/PS_cache/quant-ph/pdf/0611/0611032v1.pdf I quote:

This was taken from the conclusion of the link you provided. Most of the discussion on relativistic variations in that paper was about what constituted a Bohm-like interpretation. If the state of BM is really as advanced as you claim, that doesn't seem like the most salient point to be discussing. The thing I found most striking in both that document and in http://www.iqc.ca/~qipcourse/interpret/lectures/lec-09-10-dBB.pdf
is the problem of quantum equilibrium. As far as I can see, even non-relativistic BM cannot claim to be substantially conceptually superior to orthodox QM until that question is resolved satisfactorily. It may just be because of the imperfect english in which the second is written, but it looks to me like the probabilities in BM currently just piggy-back the successes of othodoxy. In any event, conceptual coherence is not enough for a theory to become accepted; it needs to explain the experimental facts. It might do this better than classical mechanics, but when current research is into QFT, explaining the two-slit experiment is not enough. Additionally, the impression those links give me is that a great deal of BM research involves coercing it in such a way that it can borrow successes from the orthodox approach. This doesn't drive science forward, and until a coherent picture emerges of the role of probability in the theory (apart from loose language about it being epistemic rather than ontological) it doesn't even give us a physically interesting picture.
Don't get me wrong. I think the central idea is an extremely interesting one. But until it's substantially more sophisticated and conceptually robust, it cannot be championed in anything other than a tentative way.

Muppet, may I recommend that you go back and read my posts more carefully (and also those articles for that matter). I addressed your defense of Reilly's argument quite specifically. By the way, you clearly took that quote out of context. Also, first you ask for conclusive evidence that the theory reproduce the empirical predictions of standard QM, before people like Reilly study it - well, that paper you misquote gives exactly that. And then, you act like that is not good enough a reason for people like Reilly to study the theory. Very odd! Also, the conclusion of the author that these Bohm-like theories are not intended to add anything empirically new is his own opinion and is not shared by some other more authoritative researchers in the field (this review paper was also written before the newer results). As I have cited in many other places, other researchers like Valentini, Pearle, and Tumulka have provided examples of where pilot wave theories do make new testable predictions. This also applies to your comments about quantum equilibrium. In fact, the issues of quantum probabilities have been very thoroughly treated - you just have not understood them or studied them, quite frankly. FYI, see these papers:

Valentini, A. (1991) Signal-locality, uncertainty, and the subquantum H -theorem. I, Physics Letters A 156, 5-11.

Valentini, A. (1991) Signal-locality, uncertainty, and the subquantum H -theorem. II, Physics Letters A 158, 1-8.

Generalizations of quantum mechanics.
Philip M. Pearle (Hamilton Coll.) , Antony Valentini (Perimeter Inst. Theor. Phys.) . Jun 2005. 15pp.
To be published in: Encyclopedia of Mathematical Physics, eds. J.-P. Francoise, G. Naber and T.S. Tsun (Elsevier, 2006).
e-Print: quant-ph/0506115

Bohm, D.; Vigier, J.P.
Model of the causal interpretation of quantum theory in terms of a fluid with irregular fluctuactions. (English)
[J] Phys. Rev., II. Ser. 96, 208-216 (1954).

On the Uniqueness of Quantum Equilibrium in Bohmian Mechanics
S. Goldstein and W. Struyve
J. Stat. Phys. 128, 1197-1209 (2007)
http://arxiv.org/PS_cache/arxiv/pdf/0704/0704.3070v1.pdf

Quantum Equilibrium and the Origin of Absolute Uncertainty
Detlef Dürr, Sheldon Goldstein and Nino Zanghí
Journ. of Statistical Phys. 67, 843-907 (1992)
http://eprintweb.org/S/authors/All/go/S_Goldstein/17

Quantum Equilibrium and the Role of Operators as Observables in Quantum Theory
Detlef Dürr, Sheldon Goldstein and Nino Zangh`i
http://eprintweb.org/S/authors/All/go/S_Goldstein/16

On the quantum probability flux through surfaces
M. Daumer, D. Duerr, S. Goldstein and N. Zanghi
published in Journal of Statistical Physics, August 97
http://eprintweb.org/S/authors/All/go/S_Goldstein/39

Dynamical origin of quantum probabilities.
Antony Valentini (Perimeter Inst. Theor. Phys.) , Hans Westman (Chalmers U. Tech.) . Mar 2004. 25pp.
e-Print: quant-ph/0403034

These papers are not things you can just skim and get a reasonable conclusion from - to understand them, you have to hunker down and read them carefully. I can guide you on that if you're interested.

Also, as I have said dozens of times, deBB theory does reproduce the predictions of QED, and there are proposals on how to generalize it to the Standard Model and even string field theory. Also, I have already given examples of the practical use of deBB theory.

 

[ZapperZ]

LMAO, no offense, but its funny because this is exactly what I was talking about! Anyway, see volume III of the Feynman lectures on Physics, page 21-12 and 21-13. Equations 21.31 - 21.33 are exactly the equations of BQM. Equation 21.31 is the de Broglie-Bohm guiding equation, and the last term in 21.33 is in fact just the Bohm quantum potential, while 21.38 is the quantum potential plus Lorentz force. Feynman says "the last term [in equation 21.33], which should be the energy of compression of the fluid, has a rather strange dependence on the density rho", which is funny because he was well familiar with BQM and was in fact good friends with David Bohm. I suspect he didn't mention that it is a "hidden variables" theory because back then, the subject was far more taboo among physicists than it is today, and he was writing these lectures for introductory undergraduate physics students, and he probably felt it would be inappropriate to make a mention to it. In any case, you should be able to find these equations in any other textbook on superconductivity theory. Also, see subsection 4.2.1 (Bose-Einstein condensates) under section 4.2 (Quantum models) of the review paper by Visser et al., on "Analogue Gravity":

I believe you have not answered my specific question, i.e. to point to me where in Mahan is this being used, and where in Tinkham is it also being used to derive superconducting phenomenon. If it is true that they have done it way back then, then it makes no sense that BCS would get the Nobel prize.

Look at equations 191 - 194. Again, those are exactly the equations of BQM. Unlike Feynman, they correctly refer to them as the "Madelung equations" since E. Madelung was the first to publish them in 1924 and show that they are mathematically equivalent to the Schroedinger equation. de Broglie then followed suit by presenting them as the full-fledged quantum mechanical pilot wave theory at the 1927 Solvay Conference. Then Bohm revived the pilot wave theory in 1952. So these were how the equations of superconductivity, superfluidity, BEC's etc, were discovered.

What exactly are these "equations of superconductivity, superfluidity..."? Are you confusing the phenomenological equation that is equivalent to the London equations with the actual "equation of superconductivity"? Can you show me that these formulations actually preceeded Cooper in formulating his paring state?

So far, these have been extremely hand waving. You cited a bunch of things without actually answering the specific issues that I had asked for you to address. In case you have forgotten, here they are again, for the very last time:

1. Your claim that condensed matter physics make use of these formulation. I asked specifically for you to show out of Mahan's text where this is so. Mahan text is almost the standard text for condensed matter physics.

2. I asked you to show an actual derivation (not some phenomenological model) of superconductivity that is on par with BCS theory that did not use either the field theoretic method or variational method, as shown in Tinkham's text, which again is a very well-known text in the study of superconductivity.

Zz.

 

[Maaneli]

I believe you have not answered my specific question, i.e. to point to me where in Mahan is this being used, and where in Tinkham is it also being used to derive superconducting phenomenon. If it is true that they have done it way back then, then it makes no sense that BCS would get the Nobel prize.



What exactly are these "equations of superconductivity, superfluidity..."? Are you confusing the phenomenological equation that is equivalent to the London equations with the actual "equation of superconductivity"? Can you show me that these formulations actually preceeded Cooper in formulating his paring state?

So far, these have been extremely hand waving. You cited a bunch of things without actually answering the specific issues that I had asked for you to address. In case you have forgotten, here they are again, for the very last time:

1. Your claim that condensed matter physics make use of these formulation. I asked specifically for you to show out of Mahan's text where this is so. Mahan text is almost the standard text for condensed matter physics.

2. I asked you to show an actual derivation (not some phenomenological model) of superconductivity that is on par with BCS theory that did not use either the field theoretic method or variational method, as shown in Tinkham's text, which again is a very well-known text in the study of superconductivity.

Zz.

Zapper, I think that's being too captious. The Madelung equations are not "just" a "phenomeonological model" (I'm not sure what you think phenomenological means). They are the dynamical equations of a superconducting fluid. They are deduced from the Schroedinger equation in exactly the way I pointed out.

Feynman also says: "Schroedinger's equation for the electron pairs in a superconductor gives us the equations of motion of an electrically charged ideal fluid. Superconductivity is the same as the problem of the hydrodynamics of a charged liquid. If you want to solve any problem about superconductors you take these equations for the fluid adn combine them with the Maxwell equations to get the fields" p. 21-13/14.

This is a standard part of superconductivity and BEC theory from every treatment I have seen. Here is yet another one from my graduate classical electrodynamics course with Prof. Kostya Likharev:

http://mysbfiles.stonybrook.edu/~klikharev/505-506/F07-S08/Ch6.pdf

These are my claims, and you either understand them or don't.

Also, I don't have a copy of Mahan's text with me. But from what I can gather from Mahan's text on Amazon, check chapters 10 and 11. I showed you what the equations look like by citing those other reputable references so that you can see them with your eyes, and look them up in Mahan's or whoever's texts with your hands (which I'm assuming you're capable of doing?).

<< If it is true that they have done it way back then, then it makes no sense that BCS would get the Nobel prize. >>

Red herring.

<< Can you show me that these formulations actually preceeded Cooper in formulating his paring state? >>

Well, let's see, the first time Cooper presented his theory was 1956. So Cooper's theory definitely came well afterwards.


Hope you better understand now.

 

[ZapperZ]

Zapper, I think that's being too captious. The Madelung equations are not "just" a "phenomeonological model" (I'm not sure what you think phenomenological means). They are the dynamical equations of a superconducting fluid. They are deduced from the Schroedinger equation in exactly the way I pointed out.

Feynman also says: "Schroedinger's equation for the electron pairs in a superconductor gives us the equations of motion of an electrically charged ideal fluid. Superconductivity is the same as the problem of the hydrodynamics of a charged liquid. If you want to solve any problem about superconductors you take these equations for the fluid adn combine them with the Maxwell equations to get the fields" p. 21-13/14.

This is a standard part of superconductivity and BEC theory from every treatment I have seen. Here is yet another one from my graduate classical electrodynamics course with Prof. Kostya Likharev:

http://mysbfiles.stonybrook.edu/~klikharev/505-506/F07-S08/Ch6.pdf

These are my claims, and you either understand them or don't.

But I understand it pretty well. That's why I compared them to the London equation!

For example, look at the Ginzburg-Landau treatment of it when you get what we now call the order parameter of the "wavefunction". You can get practically all the dynamical model of the system out of it as well. But do you see this as being credited as the microscopic theory of superconductivity?

Your claim that such microscopic theory predates BCS is inconsistent to the history of physics, i.e. why did BCS theory as formulated by Bardeen et al. was the one credited to be given the Nobel prize?

Also, I don't have a copy of Mahan's text with me. But from what I can gather from Mahan's text on Amazon, check chapters 10 and 11. I showed you what the equations look like by citing those other reputable references so that you can see them with your eyes, and look them up in Mahan's or whoever's texts with your hands (which I'm assuming you're capable of doing?).

So without actually looking at the text, you are able to do such a thing? Is this a common practice of yours? Note that you made the claim about how this is used throughout condensed matter theory. So it is rather puzzling how you are that confident in making such a statement when you don't have a text that practically every condensed matter physics student either has, or is very familiar with. That's like making a claim about classical E&M when you are not familiar with Jackson's classical E&M text.

Please show me exactly where in these chapters that support your argument. Why would this validates what you are claiming (i.e. such a description is used extensively in condensed matter), when the WHOLE BOOK makes use of the standard description of QM and not just in "chapters 10 and 11"?

<< If it is true that they have done it way back then, then it makes no sense that BCS would get the Nobel prize. >>

Red herring.

No, it is a fact. Read the Nobel citation.

<< Can you show me that these formulations actually preceeded Cooper in formulating his paring state? >>

Well, let's see, the first time Cooper presented his theory was 1956. So Cooper's theory definitely came well afterwards.

Of course, but just because it came later, does not mean that some similar was formulated BEFORE Cooper's treatment. So you really, again, didn't answer my question. Classical mechanics came before Cooper's theory as well, but was classical mechanics used formulate something similar? NOPE! See how you really didn't answer my question by simply saying that you just said?

Hope you better understand now.

All I have better understood is the way you avoided going into the specific question that I had asked.

 

[reilly]

Reilly, word-of-mouth communication was not primarily how the ideas of Einstein, Bohr, Feynman propagated. They propagated primarily through their published papers and debates at major physics conferences like Solvay and such. Also, to think that word-of-mouth communication is a reliable way to sort out what ideas are worthwhile and what ideas are not, is the most extremely unscientific and statistically unreliable way of doing things. And I think most people on this forum (most of the physicists) would probably agree with me on this. As you and Zapper hopefully saw, BQM equations are the backbone of superconductivity dynamics, and yet you were completely unaware of that. So really, how reliable is that "word-of-mouth" communication?

Also, 50 years ago there wasn't sympathy to Bohm's ideas contrary to what you think. Indeed, if you care to study the history of it, you would see that Bohm was marginalized by Rosenfeld, Oppenheimer, Bohr, Pauli, etc., and kicked out of Princeton partially for his hidden variables work. It's also 100% false to say that BQM is basically dead today, especially after I told you about where it is being used. Let me also mention that some string theorists like Brian Greene have recently started working on field theoretic extensions of BQM. Also, BQM is still very much alive and well in the quantum foundations community.

Maaneli -- Let's try it one more time. Most definitions of word-of-mouth say; A talks to B, who might talk to C&D, who might talk to A... So I'm talking about discussions in the coffee room, in people's offices, after class discussions with professors, talk over a beer or dinner. This WOM is often how physicists absorb new work, stimulated by lectures and papers. Quite the contrary to your dismissal of WOM, it is a major, major way of transmitting ideas within the physics communities.(I know this from my own experience.)

Why do I say word-of-mouth(WOM) was how work of Einstein, Bohr, Feynman, and Bohm was spread? I was not around for Einstein and Bohr, so I rely on their biographies by Pais. but I do know a bit about Feynman and Bohm's work and the reception thereof. I know, for a fact, that WOM was a major activity at Harvard, Stanford, Berkeley,Tufts, Rockefeller University, the Fermi Lab, Universities of Minnesota and Washington, and an unnamed school in Moscow, so long ago that I don't remember if it was Moscow University or another place. I was a student and professor in the late 50s and the 1960s, and participated in WOM, as did my colleagues.

Know initially that, in the late 40s. for QED, Schwinger and Oppenheimer were the alpha males. Feynman's work was not well received at first hearing, but its practical utility won the day, almost entirely by WOM -- I know this from my professors, many of whom studied Feynman's approach, even talked to Feynman; Feynman eventually triumphed in coffee rooms all over the world. And, Schwinger's approach took a back seat. (See Schweber's QED and the Men who made it. Note particularly the story of Bethe's initial Lamb Shift calculation, for a nice account of the importance of WOM)

The heavy hitters you mention did not constitute the whole of the physics community. During the late 50s, the interest in Bohm was mostly among graduate students and young professors and post-docs. But, as I've emphasized, those of us with some sympathy toward Bohm, also had a "show me" attitude. There's been precious little to show over the past 50 years. Thus, that initial pool of sympathetic young folks, have become senior members of the physics community, with little or no interest in Bohm's work -- the delivery man never showed up, nothing has happened to suggest that the physics community should reopen the Bohm file.

That some people, today, are looking at Bohm is certainly true. But, my contention that this group, which includes some heavy hitters, is a very small proportion of the whole physics community.

Either the computations we've mention exist or they don't.

If they exist, please let me know(By the way, I'm a reasonably competent theoretical physicist, with a lot of experience. And,most of the time, I read papers backwards, look at results, and then figure out how to get the results.) If, in fact, I have problems with the computations, I'll let you know.

If these computations do not exist, then we are finished. (For example, you mention some experiments which could be done to support Bohm. Do the experiments, and then let us know. Do the computations and show them to the physics community. That being done, interest in Bohm's work would grow substantially. )

As a current cliche puts it: talk-the- talk is not sufficient; you have to walk-the-walk. Or, do it, don't talk about it. Show us experiments and computations that have been done, rather than just proposed.

Definitely, muppet has it right.

Regards,
Reilly Atkinson

 

[muppet]

Muppet, may I recommend that you go back and read my posts more carefully (and also those articles for that matter). I addressed your defense of Reilly's argument quite specifically.

But not adequately. You're interested in trying to teach Reilly BM. He's interested in evidence that learning BM is worth his while. If you show him an actual paper or papers in which the specific calculations he requested have been performed, then it sounds to me like he will learn everything he needs to in order to follow those calculations. But what he doesn't want to do is spend time learning the basics of a formalism that doesn't lead anywhere. That it has the potential to go somewhere is not enough. You claimed that those calculations can be done in BM. HAS anyone done them? If so, show us.

By the way, you clearly took that quote out of context. Also, first you ask for conclusive evidence that the theory reproduce the empirical predictions of standard QM, before people like Reilly study it - well, that paper you misquote gives exactly that. And then, you act like that is not good enough a reason for people like Reilly to study the theory. Very odd!

I didn't take it out of context. Nor did I misquote it. It was a caveat to an assertion that I ommitted, no part of which serves to falsify the excerpt that I quoted, or render it misleading. Also, I explicitly stated that replicating non-relativistic QM (which is all that paper concerns itself with) was not enough. See my response to the penultimate sentence of your post.

Also, the conclusion of the author that these Bohm-like theories are not intended to add anything empirically new is his own opinion and is not shared by some other more authoritative researchers in the field (this review paper was also written before the newer results).

If you don't like your own references...

As I have cited in many other places, other researchers like Valentini, Pearle, and Tumulka have provided examples of where pilot wave theories do make new testable predictions. This also applies to your comments about quantum equilibrium. In fact, the issues of quantum probabilities have been very thoroughly treated - you just have not understood them or studied them, quite frankly. ...

My observations about the probability distribution were perfectly valid conclusions to draw from the two references I specified. Both regarded that as an open problem. One of the links which you have now provided appears to provide a more adequate treatment of this issue. But please don't imply I'm an idiot based on conclusions I drew because you shot yourself in the foot with your choice of references. Additionally, both of those papers did not say that it was unknown why the universe should be subject to the quantum equilibrium hypothesis, but instead described various possible ways in which it could be explained. I'm sure a lot of work has gone into answering that question, but you can't declare it a closed issue unless a consensus has been achieved. A plethora of different explanations would make it scarcely better understood than QM itself.

These papers are not things you can just skim and get a reasonable conclusion from - to understand them, you have to hunker down and read them carefully. I can guide you on that if you're interested.

Also, as I have said dozens of times, deBB theory does reproduce the predictions of QED, and there are proposals on how to generalize it to the Standard Model and even string field theory. Also, I have already given examples of the practical use of deBB theory.

If there are proposals on how to generalise it to the standard model, then it's about 40 years behind the pace. It cannot, therefore, claim to presently yield the same power or utility as the conventional formalism. Before anyone is interested in investing the effort necessary to fully master deBB they want to see evidence that this chasm is not as wide or deep as it appears. I find all of the interpretational questions interesting. But in my future intended career in research, there won't be enough hours in a human lifetime to study all possible avenues that present themselves. I, like everyone else, will have to gamble on the outcomes of my lines of enquiry. This will mean foccusing on what is most likely to tell us something new. A theory that is struggling to replicate the successes of 40 years ago seems a weak bet. DeBB will, therefore, remain merely an intellectual curiosity to indulge when other interests permit it until such time as it is vaguely comparable to the alternatives in its utility. No-one with the intention of going anywhere in a hurry knowingly traverses a cul-de-sac. Until you accept that this is the attitude of the majority of the physics community towards DeBB, you can throw introductory review papers in bad English at us until you're blue in the face; your condescension about our "lack of understanding" merely makes it appear that you miss our point entirely, and as a means of sabotaging future productive dialogue is second only to outright crackpottery.

Can this alternate theory allow us to
1. compute the electron's magnetic moment to 13 decimal places as is done with standard QED, 2. compute the pion-nucleon scattering S-matrices; 3. derive the Fermi-Thomas approximation, or equivalent thereof, used in atomic physics(heavy elements)4. can this approach bring anything new to the issue of quark containment?

Please, provide references specific to these questions. Preferably without philosophical or historical preambles.

 

[Maaneli]

But not adequately. You're interested in trying to teach Reilly BM. He's interested in evidence that learning BM is worth his while. If you show him an actual paper or papers in which the specific calculations he requested have been performed, then it sounds to me like he will learn everything he needs to in order to follow those calculations. But what he doesn't want to do is spend time learning the basics of a formalism that doesn't lead anywhere. That it has the potential to go somewhere is not enough. You claimed that those calculations can be done in BM. HAS anyone done them? If so, show us.

It's very weird that you're speaking so much on behalf of Reilly as if you're his representative or something. Why don't you just speak for your self and let him speak for hisself.

I didn't take it out of context. Nor did I misquote it. It was a caveat to an assertion that I ommitted, no part of which serves to falsify the excerpt that I quoted, or render it misleading. Also, I explicitly stated that replicating non-relativistic QM (which is all that paper concerns itself with) was not enough. See my response to the penultimate sentence of your post.

In relation to your later comments, yes you absolutely did take it out of context. The sentence right before basically says it is simply false to say that deBB theory is not compatible with QFT. Also it is obviously wrong to say that all that paper concerns itself with is replicating nonrelativistic QM, and the fact that you say this proves that you didn't read the paper at all - just like you didn't read my other post about Bell's theorem, beyond just seeing the titles of the references and making your own misguided assumptions. Is this how you work? You skim through peoples words and then draw false conclusions? As a physics student you should learn to be more careful in your reading. Go back and look at the sections and subsections and see the obvious discussions of relativistic and field theoretic extensions of deBB theory.

If you don't like your own references...

I like my references just fine. I just pointed out that there are authors with different opinions, and that relative to the progress in the field, Passon's conclusions are a bit outdated. As you continue on in your degree, you'll learn that such distinctions are perfectly OK.

A plethora of different explanations would make it scarcely better understood than QM itself.

You obviously don't understand where the probabilities in either standard QM or deBB theory come from. The whole point is that standard QM only postulates rho = |psi|^2 because it seems to work for experiments - it doesn't explain anything. deBB theory however points out that this does not have to be a postulate, and can be derived from the same statistical mechanical arguments used to justify thermodynamic equilibrium, and it also points out that it is possible for quantum equilibrium to emerge from initial nonequilbrium dynamics via the subquantum H-theorem, which implies new physics beyond standard QM. Only in that sense is it still an open question, and that is quite a newer and different situation than in standard QM.

your condescension about our "lack of understanding" merely makes it appear that you miss our point entirely, and as a means of sabotaging future productive dialogue is second only to outright crackpottery.

In your case the condescension is well-justified considering that you "started it" so to speak with all your intial talking down, self-contradicting arguments, and blatantly obvious misreadings and misunderstandings of the material I presented.

 

[Maaneli]

But I understand it pretty well. That's why I compared them to the London equation!

For example, look at the Ginzburg-Landau treatment of it when you get what we now call the order parameter of the "wavefunction". You can get practically all the dynamical model of the system out of it as well. But do you see this as being credited as the microscopic theory of superconductivity?

Your claim that such microscopic theory predates BCS is inconsistent to the history of physics, i.e. why did BCS theory as formulated by Bardeen et al. was the one credited to be given the Nobel prize?

Woa Woa Woa, now you took everything I said COMPLETELY out of context. Nowhere did I claim that the Madelung equations were a microscopic theory that predates BCS theory. That was YOUR inference. I said what I said above, no more and no less than their validity. Please get that straight once and for all. I said these equations have great and common utility to superconductivity theory, and I proved that with my references.

So without actually looking at the text, you are able to do such a thing? Is this a common practice of yours? Note that you made the claim about how this is used throughout condensed matter theory. So it is rather puzzling how you are that confident in making such a statement when you don't have a text that practically every condensed matter physics student either has, or is very familiar with.

You sound very confused, as well as someone who hasn't lifted a finger to understand why I suggested ch. 10 and 11 of Mahan. If you care to open the book with your hands, you'll notice that ch. 10 and 11 are the chapters on superconductivity and superfluidity. That's obviously the most logical place to look. Do similarly for Tinkham.

That's like making a claim about classical E&M when you are not familiar with Jackson's classical E&M text.

. Just because someone isn't familiar with Jackson's EM text (not that I am not) doesn't have anything at all to do with their credibility or the validity of what they say. Furthermore, many schools like UCLA or even Stony Brook teach EM from different texts like Milton/Schwinger or Landau/Lifschitz, which has many things in it that Jackson doesn't have. Seriously, lay off all these argumentums ad authoritarium (a big-time logical fallacy by the way).

Please show me exactly where in these chapters that support your argument. Why would this validates what you are claiming (i.e. such a description is used extensively in condensed matter), when the WHOLE BOOK makes use of the standard description of QM and not just in "chapters 10 and 11"?

See above.

No, it is a fact. Read the Nobel citation.

Doesn't matter if it is a fact. That doesn't not make it a red herring. See the definition of a red herring: http://www.merriam-webster.com/dictionary/redherring

Of course, but just because it came later, does not mean that some similar was formulated BEFORE Cooper's treatment. So you really, again, didn't answer my question. Classical mechanics came before Cooper's theory as well, but was classical mechanics used formulate something similar? NOPE! See how you really didn't answer my question by simply saying that you just said?

Again, I didn't say the Madelung equations is a microscopic like BCS. And wow, that's a disingenuous analogy if I've ever seen one. Madelung equations preceeding BCS is comparable to the relation of classical mechanics and BCS?

All I have better understood is the way you avoided going into the specific question that I had asked.

All I have better understood is the way you avoided the self-evident and direct meaning of my words and all the evidence and references I gave in support of it. Seriously, nothing good can come out of your being captious and I will not play into it like a dog.

 

[ZapperZ]

Woa Woa Woa, now you took everything I said COMPLETELY out of context. Nowhere did I claim that the Madelung equations were a microscopic theory that predates BCS theory. That was YOUR inference. I said what I said above, no more and no less than their validity. Please get that straight once and for all. I said these equations have great and common utility to superconductivity theory, and I proved that with my references.

You sound very confused, as well as someone who hasn't lifted a finger to understand why I suggested ch. 10 and 11 of Mahan. If you care to open the book with your hands, you'll notice that ch. 10 and 11 are the chapters on superconductivity and superfluidity. That's obviously the most logical place to look. Do similarly for Tinkham.

. Just because someone isn't familiar with Jackson's EM text (not that I am not) doesn't have anything at all to do with their credibility or the validity of what they say. Furthermore, many schools like UCLA or even Stony Brook teach EM from different texts like Milton/Schwinger or Landau/Lifschitz, which has many things in it that Jackson doesn't have. Seriously, lay off all these argumentums ad authoritarium (a big-time logical fallacy by the way).

See above.

Doesn't matter if it is a fact. That doesn't not make it a red herring. See the definition of a red herring: http://www.merriam-webster.com/dictionary/redherring

Again, I didn't say the Madelung equations is a microscopic like BCS. And wow, that's a disingenuous analogy if I've ever seen one. Madelung equations preceeding BCS is comparable to the relation of classical mechanics and BCS?

All I have better understood is the way you avoided the self-evident and direct meaning of my words and all the evidence and references I gave in support of it. Seriously, nothing good can come out of your being captious and I will not play into it like a dog.

I somehow knew this would happen. You have forgotten what the original contention was, so here it is again:

For example, the hydrodynamical equations of motion for superfluids and Bose-Einstein condensates, are in fact the equation of BQM, as you'll see. In fact, Feynman even derives teh equations in his Lectures when he talks about superfluids. You can also see them in all the condensed matter theory textbooks. So in fact, much of condensed matter physics owes its practical and methodological success to the work of Madelung, Takabayasi, de Broglie, and Bohm, which was initially focused on interpretational questions about QM.

I then specifically asked you to show this:

Er... back up a bit. Where exactly is this in, say, Mahan's text?

And since when is the "hydrodynamical equations of motion for superfluids and BE condensate" is equivalent to an actual derivation of these phenomena via First Principles? I thought I am aware, being a condensed matter physicist AND someone who specialized in superconductivity, of all the derivation of conventional superconductivity (both using field theoretic and variational methods - refer to Tinkham's text). Are you claiming that these are "BQM" equations? Can you please show me papers that claim and derived these explicitly?

So what exactly did you think when I asked you "...since when is the "hydrodynamical equations of motion for superfluids and BE condensate" is equivalent to an actual derivation of these phenomena via First Principles?..."

The FACT that you were arguing with me that these are NOT phenomenological models when I equate them to the London equations clearly showed that you think that these description actually derived the superconducting phenomenon. And what did you think when I talked about DERIVING such equation? Hand-waving argument, or actual MICROSCOPIC derivation as done by BCS?

You have done nothing that I asked for in the very beginning. Your apparent attack of my understanding of what you did is, in fact, a very good red herring that I'm not biting.

Zz.

 

[Maaneli]

I somehow knew this would happen. You have forgotten what the original contention was, so here it is again:



I then specifically asked you to show this:



So what exactly did you think when I asked you "...since when is the "hydrodynamical equations of motion for superfluids and BE condensate" is equivalent to an actual derivation of these phenomena via First Principles?..."

The FACT that you were arguing with me that these are NOT phenomenological models when I equate them to the London equations clearly showed that you think that these description actually derived the superconducting phenomenon. And what did you think when I talked about DERIVING such equation? Hand-waving argument, or actual MICROSCOPIC derivation as done by BCS?

You have done nothing that I asked for in the very beginning. Your apparent attack of my understanding of what you did is, in fact, a very good red herring that I'm not biting.

Zz.

I don't think I have not forgotten the original contention. You still don't seem to get that I never said this was a microscopic derivation of superconductivity. My statement that

"For example, the hydrodynamical equations of motion for superfluids and Bose-Einstein condensates, are in fact the equation of BQM, as you'll see. In fact, Feynman even derives teh equations in his Lectures when he talks about superfluids. You can also see them in all the condensed matter theory textbooks."

has always been my claim, and it is exactly accurate. Of course, unless I have seen every single condensed mattter theory textbook, I can't prove that last sentence, so maybe I overstated that part a little. But I did cite many other high quality references, and that should be enough for you to agree with my claim.

Moreover, your question/objection that

<< And since when is the "hydrodynamical equations of motion for superfluids and BE condensate" is equivalent to an actual derivation of these phenomena via First Principles?>>

had nothing to do with my claim. Since when does saying "the hydrodynamical equations of motion for superfluids and Bose-Einstein condensates, are in fact the equation of BQM" imply that I am claiming this is equivalent to an actual derivation from First Principles? NEVER!

<< The FACT that you were arguing with me that these are NOT phenomenological models when I equate them to the London equations clearly showed that you think that these description actually derived the superconducting phenomenon. >>

No it doesn't. I just didn't agree with your definition of phenomenological as "handwaving" (in fact I asked you what you meant by that). But in any case, if what you really meant was that they just don't constitue a micrscopic derivation, then, yes, they are "phenomenological". But that is still quite tangential to my original claim.

<< Hand-waving argument, or actual MICROSCOPIC derivation as done by BCS? >>

I disagree with this characterization as well. It is definitely not a "handwaving" argument (handwaving means there is no math behind it, just some fuzzy intuitive argument). That just sounds like an attempt to trivialize it.

<< You have done nothing that I asked for in the very beginning. >>

Er... yes I have. I have answered your questions directly, and it seems like you just don't like the answers. If you don't like them, well, that's ultimately YOUR problem and a result of YOUR misunderstanding of what I claimed in the first place. I can't and won't try to spoonfeed you the information.

 

[ZapperZ]

I don't think I have not forgotten the original contention. You still don't seem to get that I never said this was a microscopic derivation of superconductivity. My statement that

"For example, the hydrodynamical equations of motion for superfluids and Bose-Einstein condensates, are in fact the equation of BQM, as you'll see. In fact, Feynman even derives teh equations in his Lectures when he talks about superfluids. You can also see them in all the condensed matter theory textbooks."

has always been my claim, and it is exactly accurate. Of course, unless I have seen every single condensed mattter theory textbook, I can't prove that last sentence, so maybe I overstated that part a little. But I did cite many other high quality references, and that should be enough for you to agree with my claim.

But if this is really what you are trying to say, then you are guilty of piggy-backing onto something that has nothing to do with each other. You claim that BQM equations ARE the "hydrodynamical equations of motion...". That's just not right even IF these hydrodynamical equations are equivalent to the BQM equations simply because such equations were NOT derived that way in those texts that I've mentioned. That's why I asked you to show where these are done in Mahan text. You made the misleading implications that such techniques were done in standard condensed matter treatment, which is not correct. The derivation of superconductivity did not use BQM equations or starting "interpretation" even IF what it came up with are "BQM equations" (which is still a matter of contention). So why such a thing is even implicated is beyond me.

Moreover, your question/objection that

<< And since when is the "hydrodynamical equations of motion for superfluids and BE condensate" is equivalent to an actual derivation of these phenomena via First Principles?>>

had nothing to do with my claim. Since when does saying "the hydrodynamical equations of motion for superfluids and Bose-Einstein condensates, are in fact the equation of BQM" imply that I am claiming this is equivalent to an actual derivation from First Principles? NEVER!

<< The FACT that you were arguing with me that these are NOT phenomenological models when I equate them to the London equations clearly showed that you think that these description actually derived the superconducting phenomenon. >>

No it doesn't. I just didn't agree with your definition of phenomenological as "handwaving" (in fact I asked you what you meant by that). But in any case, if what you really meant was that they just don't constitue a micrscopic derivation, then, yes, they are "phenomenological". But that is still quite tangential to my original claim.

.. and that is exactly my point. I can derive such "hydrodynamical" equation using CONVENTIONAL field-theoretic method. I then arrive at these "hydrodynamical equations", which you claim are "BQM equations". What have I proven? That BQM equations are NOT fundamental, per your admission that you never claim that such a thing can be derive from First Principles. So your earlier claim of

So in fact, much of condensed matter physics owes its practical and methodological success to the work of Madelung, Takabayasi, de Broglie, and Bohm, which was initially focused on interpretational questions about QM.

.. is a seriously misleading statement especially when the majority of "methodological" treatment done in condensed matter is via field theoretic method. Condensed matter physics does not "owes its practical and methodological success" to anything other than the conventional interpretation of QM. That is why I wanted to know where in Mahan is such non-conventional interpretation was ever used as the starting point for any of the phenomenon that was covered. The best you can do is claim that the resulting equations are "BQM". By doing that, you have implicitly designated BQM as not being fundamental.

Zz.

 

[peter0302]

Note also we still haven't seen an answer to Reilly's question.

 

[Maaneli]

But if this is really what you are trying to say, then you are guilty of piggy-backing onto something that has nothing to do with each other. You claim that BQM equations ARE the "hydrodynamical equations of motion...". That's just not right even IF these hydrodynamical equations are equivalent to the BQM equations simply because such equations were NOT derived that way in those texts that I've mentioned. That's why I asked you to show where these are done in Mahan text. You made the misleading implications that such techniques were done in standard condensed matter treatment, which is not correct. The derivation of superconductivity did not use BQM equations or starting "interpretation" even IF what it came up with are "BQM equations" (which is still a matter of contention). So why such a thing is even implicated is beyond me.



.. and that is exactly my point. I can derive such "hydrodynamical" equation using CONVENTIONAL field-theoretic method. I then arrive at these "hydrodynamical equations", which you claim are "BQM equations". What have I proven? That BQM equations are NOT fundamental, per your admission that you never claim that such a thing can be derive from First Principles. So your earlier claim of



.. is a seriously misleading statement especially when the majority of "methodological" treatment done in condensed matter is via field theoretic method. Condensed matter physics does not "owes its practical and methodological success" to anything other than the conventional interpretation of QM. That is why I wanted to know where in Mahan is such non-conventional interpretation was ever used as the starting point for any of the phenomenon that was covered. The best you can do is claim that the resulting equations are "BQM". By doing that, you have implicitly designated BQM as not being fundamental.

Zz.

Zapper,


Once again you're either just confused on your own accord, or are intentional refusing to acknolwedge this fact. For the last time, my claim is that "the hydrodynamical equations of motion for superfluids and Bose-Einstein condensates, are in fact the equation of BQM". That is absolutely correct. Feynman also basically agreed with me, even though he didn't explicitly call those equations "BQM" (though if you cared to look at his book, which I don't think you even did, he did refer to the quantum potential). Are you daring to say Feynman was wrong?

<< even IF what it came up with are "BQM equations" (which is still a matter of contention)>>

No it is not a matter of contention. Get your facts straight and look at my references.


<< .. and that is exactly my point. I can derive such "hydrodynamical" equation using CONVENTIONAL field-theoretic method. >>

That's interesting that you say you can derive the Madelung equations from field theoretic methods, because that also means that you can derive the Schroedinger equation, and therefore that the Schroedinger equation and wavefunction are not fundamental either. You'll have to understand if I'm skeptical of your claim. Can you provide me with a derivation of this claim?



<< The best you can do is claim that the resulting equations are "BQM". >>

Yes! Now you understand. That's been my claim all along!

<< By doing that, you have implicitly designated BQM as not being fundamental. >>

By your logic, then neither are the Schroedinger equation and wavefunction. Again, please provide me with a derivation of your claim. But, you should know that the equations of deBB theory apply perfectly well to a single electron, or 2 electrons, or N electrons.


<< Condensed matter physics does not "owes its practical and methodological success" to anything other than the conventional interpretation of QM. >>


No, the way you quote me brought it out of context. It sounds like I'm saying all of condensed matter owes its success to the equations of BQM, which is not what I said. I said it owes much of its practical and methodological success to the equations of QM. But I should have been more specific, namely, the theory of superconductiivyt and superfluidity owes much of its practical success to the equations of BQM. And indeed that is definitely true as Feynman, Likharev, Visser et al., show.

 

[ZapperZ]

Zapper,


Once again you're either just confused on your own accord, or are intentional refusing to acknolwedge this fact. For the last time, my claim is that "the hydrodynamical equations of motion for superfluids and Bose-Einstein condensates, are in fact the equation of BQM". That is absolutely correct. Feynman also basically agreed with me, even though he didn't explicitly call those equations "BQM" (though if you cared to look at his book, which I don't think you even did, he did refer to the quantum potential). Are you daring to say Feynman was wrong?

<< even IF what it came up with are "BQM equations" (which is still a matter of contention)>>

No it is not a matter of contention. Get your facts straight and look at my references.


<< .. and that is exactly my point. I can derive such "hydrodynamical" equation using CONVENTIONAL field-theoretic method. >>

That's interesting that you say you can derive the Madelung equations from field theoretic methods, because that also means that you can derive the Schroedinger equation, and therefore that the Schroedinger equation and wavefunction are not fundamental either. You'll have to understand if I'm skeptical of your claim. Can you provide me with a derivation of this claim?



<< The best you can do is claim that the resulting equations are "BQM". >>

Yes! Now you understand. That's been my claim all along!

<< By doing that, you have implicitly designated BQM as not being fundamental. >>

By your logic, then neither are the Schroedinger equation and wavefunction. Again, please provide me with a derivation of your claim. But, you should know that the equations of deBB theory apply perfectly well to a single electron, or 2 electrons, or N electrons.


<< Condensed matter physics does not "owes its practical and methodological success" to anything other than the conventional interpretation of QM. >>


No, the way you quote me brought it out of context. It sounds like I'm saying all of condensed matter owes its success to the equations of BQM, which is not what I said. I said it owes much of its practical and methodological success to the equations of QM. But I should have been more specific, namely, the theory of superconductiivyt and superfluidity owes much of its practical success to the equations of BQM. And indeed that is definitely true as Feynman, Likharev, Visser et al., show.

There's something very easy here that you can show, which corresponds to what Reilly had asked originally:

Show the exact derivation of superconductivity, etc. Example, show how, using the interpretation of your choice, the same level of success that BCS can do. Note that BCS did not just derive the "hydrodynamical" equations. Superconductivity is MORE than just charge transport!

I believe that this was what was asked of you way in the beginning.

Zz.

 

[muppet]

It's very weird that you're speaking so much on behalf of Reilly as if you're his representative or something. Why don't you just speak for your self and let him speak for hisself.

What I'm saying is based on points made in his posts that you appear to be missing.

In relation to your later comments, yes you absolutely did take it out of context. The sentence right before basically says it is simply false to say that deBB theory is not compatible with QFT.

I know exactly what it said, and I didn't claim that deBB was incompatible with QFT. I didn't quote you out of context because the sentence I omitted doesn't run contrary to the point I was making, which is that a great deal of research into deBB isn't actually driving physics forward because it's busy trying to replicate results we already have.

Also it is obviously wrong to say that all that paper concerns itself with is replicating nonrelativistic QM, and the fact that you say this proves that you didn't read the paper at all

I should have said: 'Most of the presentation of technical material within the paper was concerned with explaining the predictions of nonrelativistic QM in terms of particles subject to dynamics described by the guidance equation', but it would have made a clumsy parenthesis. You will find that I made specific references elsewhere to the nature of the discussion in that paper of relativistic extensions.

just like you didn't read my other post about Bell's theorem, beyond just seeing the titles of the references and making your own misguided assumptions. Is this how you work? You skim through peoples words and then draw false conclusions? As a physics student you should learn to be more careful in your reading. Go back and look at the sections and subsections and see the obvious discussions of relativistic and field theoretic extensions of deBB theory.

I already acknowledged and apologised for my error in the other thread, in which you made a similarly crass error. As pointed out above, I was aware of the other sections. The conclusion I drew is not that deBB is incompatible with QFT as you claim (perhaps ironically, given the nature of this accusation) but that as a predictive tool deBB in its present state has substantially less power and utility than the orthodox methods employed by the majority of researchers.

I like my references just fine. I just pointed out that there are authors with different opinions, and that relative to the progress in the field, Passon's conclusions are a bit outdated. As you continue on in your degree, you'll learn that such distinctions are perfectly OK.

OK.

You obviously don't understand where the probabilities in either standard QM or deBB theory come from. The whole point is that standard QM only postulates rho = |psi|^2 because it seems to work for experiments - it doesn't explain anything. deBB theory however points out that this does not have to be a postulate, and can be derived from the same statistical mechanical arguments used to justify thermodynamic equilibrium, and it also points out that it is possible for quantum equilibrium to emerge from initial nonequilbrium dynamics via the subquantum H-theorem, which implies new physics beyond standard QM. Only in that sense is it still an open question, and that is quite a newer and different situation than in standard QM.

I understand perfectly well that in orthodox QM (hereafter just QM) probabilities arise as a postulate that works. The reason I'm more forgiving of it in QM is that in QM the implication is that nature is intrinsically probabilistic; that this is, in fact, what nature is like. In deBB you need to explain how a deterministic system gives rise to the probabilistic distribution we observe, and neither of the initial papers provided an unambiguous or complete answer to that question. When you provided a link to a more detailed presentation of how probabilities might arise, I ackowledged it. The point of that very paragraph was to acknowedge it, and explain my criticism in terms of the previous papers. To repeat that one sentence and suggest that I was blindly repeating the same accusation in the face of a more complete answer was -dare I say it- quoting me out of context.

In your case the condescension is well-justified considering that you "started it" so to speak with all your intial talking down, self-contradicting arguments, and blatantly obvious misreadings and misunderstandings of the material I presented.

If you read my original post you'll find that whilst I was fairly emphatic in the position I adopted, I didn't say anything that implied you were an idiot. I just disagreed with you, and pointed out that you hadn't really responded to the present line of argument. My tone has self-evidently become more terse throughout these posts, in direct response to your abrasive manner and evasion of several clear requests. I also think you'll find that when you've fleshed out or elaborated upon deficiencies in the original links, I've responded to that appropriately. By contrast, you seem to be accusing me of making claims that I simply haven't, such as that deBB is incompatible with QFT. If you think that this is what I'm saying or have said at any point, then either I haven't acheived the clarity I desired or you have misunderstood me. So please, allow me one further opportunity to make my position clear, without any intention of sounding patronising:

I am NOT claiming that deBB is false, or that it is incompatible with QFT, or that it has no merit. I'm not even claiming that it is in principle impossible that it yields new physics, and I would be extremely interested to hear the outcome of any experiment in which the predictions of deBB differed from those of QM.
I AM claiming that as a predictive tool, deBB is substantially less useful than the paradigm within which most researchers operate. I base this claim in particular on the fact that the Standard Model has been subjected to incredible experimental scrutiny over the last 40 years, and passed all tests with flying colours, wheras deBB is now beginning to consider how it can be extended to include the standard model. I consider that a deficit of four decades' worth of research amounts to a substantial body of science that orthodox methods have yielded and deBB has not.
I DO also claim that such attempts as there are to formulate a bohmian QFT have less utility than their orthodox counterparts. You have the particular opportunity to convince me that this statement is false, by providing links to published works in which deBB theory reproduces predictions made by orthodox QFT and experimentally verified. This, and in my present opinion only this, constitutes sufficient evidence to refute that claim. Once again, I suggest you start with reference to calculation of those quantities suggested by reilly.

 

[reilly]

Re computations: five days and counting. r

 

[Maaneli]

What I'm saying is based on points made in his posts that you appear to be missing.


I know exactly what it said, and I didn't claim that deBB was incompatible with QFT. I didn't quote you out of context because the sentence I omitted doesn't run contrary to the point I was making, which is that a great deal of research into deBB isn't actually driving physics forward because it's busy trying to replicate results we already have.


I should have said: 'Most of the presentation of technical material within the paper was concerned with explaining the predictions of nonrelativistic QM in terms of particles subject to dynamics described by the guidance equation', but it would have made a clumsy parenthesis. You will find that I made specific references elsewhere to the nature of the discussion in that paper of relativistic extensions.


I already acknowledged and apologised for my error in the other thread, in which you made a similarly crass error. As pointed out above, I was aware of the other sections. The conclusion I drew is not that deBB is incompatible with QFT as you claim (perhaps ironically, given the nature of this accusation) but that as a predictive tool deBB in its present state has substantially less power and utility than the orthodox methods employed by the majority of researchers.


OK.


I understand perfectly well that in orthodox QM (hereafter just QM) probabilities arise as a postulate that works. The reason I'm more forgiving of it in QM is that in QM the implication is that nature is intrinsically probabilistic; that this is, in fact, what nature is like. In deBB you need to explain how a deterministic system gives rise to the probabilistic distribution we observe, and neither of the initial papers provided an unambiguous or complete answer to that question. When you provided a link to a more detailed presentation of how probabilities might arise, I ackowledged it. The point of that very paragraph was to acknowedge it, and explain my criticism in terms of the previous papers. To repeat that one sentence and suggest that I was blindly repeating the same accusation in the face of a more complete answer was -dare I say it- quoting me out of context.



If you read my original post you'll find that whilst I was fairly emphatic in the position I adopted, I didn't say anything that implied you were an idiot. I just disagreed with you, and pointed out that you hadn't really responded to the present line of argument. My tone has self-evidently become more terse throughout these posts, in direct response to your abrasive manner and evasion of several clear requests. I also think you'll find that when you've fleshed out or elaborated upon deficiencies in the original links, I've responded to that appropriately. By contrast, you seem to be accusing me of making claims that I simply haven't, such as that deBB is incompatible with QFT. If you think that this is what I'm saying or have said at any point, then either I haven't acheived the clarity I desired or you have misunderstood me. So please, allow me one further opportunity to make my position clear, without any intention of sounding patronising:

I am NOT claiming that deBB is false, or that it is incompatible with QFT, or that it has no merit. I'm not even claiming that it is in principle impossible that it yields new physics, and I would be extremely interested to hear the outcome of any experiment in which the predictions of deBB differed from those of QM.
I AM claiming that as a predictive tool, deBB is substantially less useful than the paradigm within which most researchers operate. I base this claim in particular on the fact that the Standard Model has been subjected to incredible experimental scrutiny over the last 40 years, and passed all tests with flying colours, wheras deBB is now beginning to consider how it can be extended to include the standard model. I consider that a deficit of four decades' worth of research amounts to a substantial body of science that orthodox methods have yielded and deBB has not.
I DO also claim that such attempts as there are to formulate a bohmian QFT have less utility than their orthodox counterparts. You have the particular opportunity to convince me that this statement is false, by providing links to published works in which deBB theory reproduces predictions made by orthodox QFT and experimentally verified. This, and in my present opinion only this, constitutes sufficient evidence to refute that claim. Once again, I suggest you start with reference to calculation of those quantities suggested by reilly.

What I'm saying is based on points made in his posts that you appear to be missing.


I know exactly what it said, and I didn't claim that deBB was incompatible with QFT. I didn't quote you out of context because the sentence I omitted doesn't run contrary to the point I was making, which is that a great deal of research into deBB isn't actually driving physics forward because it's busy trying to replicate results we already have.


I should have said: 'Most of the presentation of technical material within the paper was concerned with explaining the predictions of nonrelativistic QM in terms of particles subject to dynamics described by the guidance equation', but it would have made a clumsy parenthesis. You will find that I made specific references elsewhere to the nature of the discussion in that paper of relativistic extensions.


I already acknowledged and apologised for my error in the other thread, in which you made a similarly crass error. As pointed out above, I was aware of the other sections. The conclusion I drew is not that deBB is incompatible with QFT as you claim (perhaps ironically, given the nature of this accusation) but that as a predictive tool deBB in its present state has substantially less power and utility than the orthodox methods employed by the majority of researchers.


OK.


I understand perfectly well that in orthodox QM (hereafter just QM) probabilities arise as a postulate that works. The reason I'm more forgiving of it in QM is that in QM the implication is that nature is intrinsically probabilistic; that this is, in fact, what nature is like. In deBB you need to explain how a deterministic system gives rise to the probabilistic distribution we observe, and neither of the initial papers provided an unambiguous or complete answer to that question. When you provided a link to a more detailed presentation of how probabilities might arise, I ackowledged it. The point of that very paragraph was to acknowedge it, and explain my criticism in terms of the previous papers. To repeat that one sentence and suggest that I was blindly repeating the same accusation in the face of a more complete answer was -dare I say it- quoting me out of context.



If you read my original post you'll find that whilst I was fairly emphatic in the position I adopted, I didn't say anything that implied you were an idiot. I just disagreed with you, and pointed out that you hadn't really responded to the present line of argument. My tone has self-evidently become more terse throughout these posts, in direct response to your abrasive manner and evasion of several clear requests. I also think you'll find that when you've fleshed out or elaborated upon deficiencies in the original links, I've responded to that appropriately. By contrast, you seem to be accusing me of making claims that I simply haven't, such as that deBB is incompatible with QFT. If you think that this is what I'm saying or have said at any point, then either I haven't acheived the clarity I desired or you have misunderstood me. So please, allow me one further opportunity to make my position clear, without any intention of sounding patronising:

I am NOT claiming that deBB is false, or that it is incompatible with QFT, or that it has no merit. I'm not even claiming that it is in principle impossible that it yields new physics, and I would be extremely interested to hear the outcome of any experiment in which the predictions of deBB differed from those of QM.
I AM claiming that as a predictive tool, deBB is substantially less useful than the paradigm within which most researchers operate. I base this claim in particular on the fact that the Standard Model has been subjected to incredible experimental scrutiny over the last 40 years, and passed all tests with flying colours, wheras deBB is now beginning to consider how it can be extended to include the standard model. I consider that a deficit of four decades' worth of research amounts to a substantial body of science that orthodox methods have yielded and deBB has not.
I DO also claim that such attempts as there are to formulate a bohmian QFT have less utility than their orthodox counterparts. You have the particular opportunity to convince me that this statement is false, by providing links to published works in which deBB theory reproduces predictions made by orthodox QFT and experimentally verified. This, and in my present opinion only this, constitutes sufficient evidence to refute that claim. Once again, I suggest you start with reference to calculation of those quantities suggested by reilly.

I guess you guys really missed me

<< I should have said: 'Most of the presentation of technical material within the paper was concerned with explaining the predictions of nonrelativistic QM in terms of particles subject to dynamics described by the guidance equation', but it would have made a clumsy parenthesis. >>

Nah, you could have just said "that paper deals with explaining the predictions of both nonrelativistic and relativistic pilot wave QM and QFT". A word of advice - it's always better to be a little more elaborate and accurate, than to be inaccurate and concise.


<< The conclusion I drew is not that deBB is incompatible with QFT as you claim (perhaps ironically, given the nature of this accusation) but that as a predictive tool deBB in its present state has substantially less power and utility than the orthodox methods employed by the majority of researchers. >>

But you have no logical basis for establishing that conclusion if you don't even know what the relativistic and field theoretic extensions of deBB look like in the first place. It sounds like you're making the assumption that just because the majority uses one method in favor of another, the majoritarian method must be superior. That doesn't follow at all. Let me give you a counterexample: the majority of QCD theorists for a long time used the equal-time formulation, in favor of Dirac's light-front formulation. But the latter is well known to those who are familiar with it to have many more drastically superior computational advantages over the standard equal-time formulation of QCD. Unfortunately, the light-front QCD formulation was only developed much later in the 80s and 90s, and so it has taken much more time to catch on. Similarly also for Parisi-Wu stochastic quantization.

<< My tone has self-evidently become more terse throughout these posts, in direct response to your abrasive manner and evasion of several clear requests. >>

You should be more careful with accusations. I am not evading anybody.

<< I AM claiming that as a predictive tool, deBB is substantially less useful than the paradigm within which most researchers operate. I base this claim in particular on the fact that the Standard Model has been subjected to incredible experimental scrutiny over the last 40 years, and passed all tests with flying colours >>

The success of the SM doesn't have anything to do with deBB beyond putting a lower bound on the potential successfulness of the latter. You still don't seem to understand the connection between the standard and deBB versions of QT.

<< wheras deBB is now beginning to consider how it can be extended to include the standard model. I consider that a deficit of four decades' worth of research amounts to a substantial body of science that orthodox methods have yielded and deBB has not. >>

You're also making a number of false assumptions (which many newbies do), in particular, about the amount of intellectual effort that has gone into deBB theory versus standard QM. You don't seem to realize that for several decades, the theory was forgotten about (even by Bohm after his nervous breakdown and bout with depression) until the 70's when like 3 of his students revived it. And it was only until the 80's that there were more than 10 people working on the subject and clearing up the issues of its nonrelativistic and relativistic differences from standard QM. And only in the 90's and 2000's has there been more active research on quantum equilibrium issues and field theoretic extensions. Also keep in mind that the funding for this kind of research is very hard to come by for political and bureaucratic reasons. In other words, even though the theory has been around for 50+ years, the amount of intellectual manpower devoted to it has been miniscule compared to even 1 year's worth of intellectual mapower devoted to standard QM today. So it is not at all a fair comparison to make.

Now with regard to what Reilly asked and my claims, I think you misunderstood the claims muppet. Reilly asked me

"Can this alternate theory allow us to
1. compute the electron's magnetic moment to 13 decimal places as is done with standard QED, 2. compute the pion-nucleon scattering S-matrices; 3. derive the Fermi-Thomas approximation, or equivalent thereof, used in atomic physics(heavy elements)4. can this approach bring anything new to the issue of quark containment?"

I answered in the affirmative. What this amounts to is the claim that there exist field theoretic versions of pilot wave theory that are empirically equivalent to standard QED and QCD, and that one can always transcribe these calculations from the standard field theory to a pilot wave field theory, given this empirical equivalence. Also, the standard QFT and pilot wave QFT share much of the same mathematics, and much of the calculations in pilot wave theory actually go along the same lines as in the standard theory; the difference is that at the end of the day you use the wavefunctional to compute the guiding equation for the field variable (or particle) given by dPhi/dt = J/rho. So at the end of the day you see the physical process in terms of the trajectory of a field variable or particle. So none of this should come as any surprise either. Indeed for these reasons, my answers to Reilly are trivially true.

Whether anyone working on pilot wave theory has actually bothered to reproduce those specific calculations and publish them, I do not know - but that is irrelevant for the reasons above. In fact, it would be a waste of time to try and do that. It is already necessary and sufficient to show that the pilot wave field theories are empirically equivalent to the standard field theories used for the above calculations, and that it is always possible to transcribe the calculations from the standard field theories to the corresponding pilot wave field theories. Will the pilot wave field theories always provide a computational superior method? No, not necessarily, for the same reason that, for example, the path integral approach does not always provide the most computationally superior method for any QFT calculation. No single approach to field theory will necessarily be the most computationally convenient across the board: but, I would claim that unlike the other approaches, the pilot wave field theories are the most conceptually and mathematically unambiguous insofar as supplying a theory of relativistic and field theoretic measurement processes. Without further adieu, here are some of the most recent works on pilot wave field theories (from newest to oldest):

Field beables for quantum field theory, W. Struyve, to be published in Physics Reports (0707.3685 [quant-ph]).
http://arxiv.org/abs/0707.3685

A minimalist pilot-wave model for quantum electrodynamics, W. Struyve, H. Westman, Proc. Roy. Soc A 463, 3115-3129 (2007) (0707.3487 [quant-ph]).
http://arxiv.org/abs/0707.3487

A Dirac sea pilot-wave model for quantum field theory, S. Colin, W. Struyve, J. Phys. A: Math. Theor. 40, 7309-7341 (2007) (quant-ph/0701085).
http://arxiv.org/abs/quant-ph/0701085

A new pilot-wave model for quantum field theory, W. Struyve, H. Westman, in "Quantum Mechanics: Are there Quantum Jumps? and On the Present Status of Quantum Mechanics", eds. A. Bassi, D. Duerr, T. Weber and N. Zanghi, AIP Conference Proceedings 844, 321 (2006) (quant-ph/0602229).
http://arxiv.org/abs/quant-ph/0602229

For you Reilly, have a look at the first paper, and in particular, section 2.2, all of section 3, all of section 4, section 5, section 6, and section 7. That should give you all you need to get a feel for how these pilot wave field theories work and how they reproduce the predictions of standard QFT in relation to the questions you asked.

Hopefully you won't flake out on me.

 

[Maaneli]

There's something very easy here that you can show, which corresponds to what Reilly had asked originally:

Show the exact derivation of superconductivity, etc. Example, show how, using the interpretation of your choice, the same level of success that BCS can do. Note that BCS did not just derive the "hydrodynamical" equations. Superconductivity is MORE than just charge transport!

I believe that this was what was asked of you way in the beginning.

Zz.

Now Zapper, instead of avoiding my questions and putting words in my mouth, can you provide me with proof of your claim that the Schroedinger and Madelung equations are not fundamental in condensed matter physics? That's a very big claim and if it's true I want to know about it.

 

[Maaneli]

Maaneli -- Let's try it one more time. Most definitions of word-of-mouth say; A talks to B, who might talk to C&D, who might talk to A... So I'm talking about discussions in the coffee room, in people's offices, after class discussions with professors, talk over a beer or dinner. This WOM is often how physicists absorb new work, stimulated by lectures and papers. Quite the contrary to your dismissal of WOM, it is a major, major way of transmitting ideas within the physics communities.(I know this from my own experience.)

Why do I say word-of-mouth(WOM) was how work of Einstein, Bohr, Feynman, and Bohm was spread? I was not around for Einstein and Bohr, so I rely on their biographies by Pais. but I do know a bit about Feynman and Bohm's work and the reception thereof. I know, for a fact, that WOM was a major activity at Harvard, Stanford, Berkeley,Tufts, Rockefeller University, the Fermi Lab, Universities of Minnesota and Washington, and an unnamed school in Moscow, so long ago that I don't remember if it was Moscow University or another place. I was a student and professor in the late 50s and the 1960s, and participated in WOM, as did my colleagues.

Know initially that, in the late 40s. for QED, Schwinger and Oppenheimer were the alpha males. Feynman's work was not well received at first hearing, but its practical utility won the day, almost entirely by WOM -- I know this from my professors, many of whom studied Feynman's approach, even talked to Feynman; Feynman eventually triumphed in coffee rooms all over the world. And, Schwinger's approach took a back seat. (See Schweber's QED and the Men who made it. Note particularly the story of Bethe's initial Lamb Shift calculation, for a nice account of the importance of WOM)

The heavy hitters you mention did not constitute the whole of the physics community. During the late 50s, the interest in Bohm was mostly among graduate students and young professors and post-docs. But, as I've emphasized, those of us with some sympathy toward Bohm, also had a "show me" attitude. There's been precious little to show over the past 50 years. Thus, that initial pool of sympathetic young folks, have become senior members of the physics community, with little or no interest in Bohm's work -- the delivery man never showed up, nothing has happened to suggest that the physics community should reopen the Bohm file.

That some people, today, are looking at Bohm is certainly true. But, my contention that this group, which includes some heavy hitters, is a very small proportion of the whole physics community.

Either the computations we've mention exist or they don't.

If they exist, please let me know(By the way, I'm a reasonably competent theoretical physicist, with a lot of experience. And,most of the time, I read papers backwards, look at results, and then figure out how to get the results.) If, in fact, I have problems with the computations, I'll let you know.

If these computations do not exist, then we are finished. (For example, you mention some experiments which could be done to support Bohm. Do the experiments, and then let us know. Do the computations and show them to the physics community. That being done, interest in Bohm's work would grow substantially. )

As a current cliche puts it: talk-the- talk is not sufficient; you have to walk-the-walk. Or, do it, don't talk about it. Show us experiments and computations that have been done, rather than just proposed.

Definitely, muppet has it right.

Regards,
Reilly Atkinson

<< Quite the contrary to your dismissal of WOM, it is a major, major way of transmitting ideas within the physics communities.(I know this from my own experience.) >>


WOM may be a frequently relied upon way of transmitting ideas within the community, but that doesn't mean it is a reliable way in the sense that WOM gives you a statistically representative sample of all the valid ideas out there in the literature, or that it gives you a factually account of the valid ideas out there in the literature. Quite the contrary. That's just basic statistical reasoning. Also, personal experience is anecdotal and therefore also not too reliable. For example, in my own experience, many popular ideas in physics which I have seen transmitted by WOM is often misunderstood, mischaracterized, or distorted to the point that they are very misleading. A case in point. By WOM I agree with you that Bell's theorem and its implications for hidden variable theories and quantum measurement theory were transmitted to physicists across the community. But the problem with this is that the vast majority of (like 95%) the hundreds of physicists I have discussed QM foundations with, which includes not only my distinguished professors at Stony Brook, but also Nobelists and other world famous physicists, simply have a factually incorrect understanding of Bell's theorem. They think that Bell's theorem proved that all hidden variable theories are impossible and that it proved determinism and realism are impossible in quantum physics. They also think by WOM that Bell was a staunch opponent of hidden variable theories. So with this one example you can see that WOM is also sometimes not at all a reliable a way of communicating ideas and information. And also in my experience, too many senior physicists rely on WOM waaayy toooo much.

About pilot wave theories walking the walk, of course I agree with you. But you have to keep in mind the limits of the resources and manpower, and the psychological resistance that advocates of such an approach have had to endure and fight through. So it hasn't been exactly cakewalk.

 

[reilly]

Maaneli -- I read the first QED paper. I's all talk; like a weak existence theorem. We think we can do it, but...And that, after 50 years.

You have done one too many snotty, presumptious, demeaning remarks, so I cannot see the worth in paying anymore attention to you; I'm not interested in being insulted, with all due respect. Why should I give a damn about flaking out or not on you, perish the thought. Get real.

By the way, you don't understand nor appreciate WOM at all. But with experience you will change your tune.

Reilly Atkinson