Electrons travel faster than the speed of light

[peter0302]

Actually we can say what the electron is or acts like before measurement, in a scientifically meaningful way.

Perhaps it's meaningful to you in your head, but that's it.

 

[Maaneli]

Perhaps it's meaningful to you in your head, but that's it.

Actually no. It is just as meaningful as saying that a particle is a particle in classical mechanics, even before it is measured. This point can be tested and justified in a number of different ways. In particular, one can test such an interpretation by how much more it explains than another interpretation

 

[muppet]

You can certainly say that the electron is "acts like a wave" in a perfectly scientific way. The results of experiments strongly(!) support the idea that the electron's wavefunction undergoes diffraction, interference, superposition, and other wavelike phenomena. Whether you say that the wavefunction "is" the electron or "describes it" is what we can't answer, but I see nothing wrong whatever with characterising experimentally observable behaviour by analogy.

You can't "test" an interpretation, however. The definition of an interpretation is effectively the physical picture that we associate with the mathematical description of the results of observable measurement. You cannot discriminate between theories that make identical predictions using any apparatus of the scientific method. As soon as something makes distinct experimental prediction from a theory, it ceases to become an interpretation of that theory and becomes a distinct, falsifiable theory. Until such time, you're ultimately picking whichever description accords with your intuition about a particular topic.

 

[Maaneli]

why was the exchange between me and Crosson removed?

 

[peter0302]

The reason mathematics, not English, is the language of physics is because mathematics is the only language in which you can say unambiguous things in a scientifically accurate way.

"Acts like a wave" is subject to so much interrpetation that it does no good in predicting or understanding a particle's behavior. When we must speak in English, we try to do so using the most unambiguous exact terminology possible. Again, "acts like a wave" doesn't cut it.

The wave function describes the likely locations one will observe a particle. The wave function is governed by the Schrodinger Equation. That's the best you can do before you get into ambiguities and philosophies.

 

[Maaneli]

The reason mathematics, not English, is the language of physics is because mathematics is the only language in which you can say unambiguous things in a scientifically accurate way.

"Acts like a wave" is subject to so much interrpetation that it does no good in predicting or understanding a particle's behavior. When we must speak in English, we try to do so using the most unambiguous exact terminology possible. Again, "acts like a wave" doesn't cut it.

The wave function describes the likely locations one will observe a particle. The wave function is governed by the Schrodinger Equation. That's the best you can do before you get into ambiguities and philosophies.

No, it isn't the best you can do. You can do better:

$$\frac{dQ_{k}}{dt}$$ = $$\frac{\hbar}{m}$$$$\Im$$$$\frac{\left\{\nabla\psi\right\}}{\psi}$$$$\left(Q_{1}...Q_{k}\right)$$

This is the de Broglie-Bohm guidance equation for a point particle, whose velocity vector is clearly determined in part by the wavefunction. Therefore we have a perfectly mathematically rigorous way to speak of the electron as a particle 'guided' by a wave.

 

[peter0302]

Bohmian Mechanics is an interpretation of QM, not an accepted or even testable theory.

You seem to have your own ideas about things and no interest in doing anything but espousing them, so there's not much point in continuing this discussion.

 

[Maaneli]

Bohmian Mechanics is an interpretation of QM, not an accepted or even testable theory.

You seem to have your own ideas about things and no interest in doing anything but espousing them, so there's not much point in continuing this discussion.

First off, the equation I wrote down is a sharp counterexample to your mistaken belief that the Schroedinger evolution is all that one can meaningfully talk about regarding the electron, because you think it is the only mathematically well-defined statement about its physics. Also you seem to not realize that the wave function is itself not an observable field, even in standard QM.

In the first place, BM (should actually be referred to as de Broglie-Bohm theory) is not just an "interpretation" of QM, but a different formulation of QM. It involves different equations than standard QM. And it is completely false to say that it is "not an accepted or even testable theory". No single formulation or interpretation of QM (including the textbook plus decoherence approach) is accepted as "the most correct" by most physicists; but physicists who have studied the pilot wave theory admit it is self-consistent and empirically equivalent to standard QM, even if they don't like it for whatever reason. As for it being testable, indeed it is for the possibility of quantum nonequilibrium dynamics:

Dynamical Origin of Quantum Probabilities
Antony Valentini and Hans Westman
http://eprintweb.org/S/authors/All/va/Valentini/12

De Broglie-Bohm Prediction of Quantum Violations for Cosmological Super-Hubble Modes
Antony Valentini
http://eprintweb.org/S/authors/All/va/Valentini/2

Inflationary Cosmology as a Probe of Primordial Quantum Mechanics
Antony Valentini
http://eprintweb.org/S/authors/All/va/Valentini/1

Furthermore, these are not my "own ideas", and the fact that you would characterize them like that as a way to dismiss them or refuse to acknowledge them tells me that you don't and are not really interested in understanding anything different from a naive textbook approach to QM.

The ball is in your court now. I gave you a sharp counterexample to your claims that pilot wave theory is not testable or "accepted", and it is up to you to show a dignified response.

 

[Maaneli]

The reason mathematics, not English, is the language of physics is because mathematics is the only language in which you can say unambiguous things in a scientifically accurate way.

Based on this alone you should agree with me that the pilot wave theory can say "unambiguous things in a scientifically accurate way", since it is framed in precise mathematical language, not just words.

"Acts like a wave" is subject to so much interrpetation that it does no good in predicting or understanding a particle's behavior. When we must speak in English, we try to do so using the most unambiguous exact terminology possible. Again, "acts like a wave" doesn't cut it.

What does it mean for you to "understand" a particle's behavior, in distinction from predicting its behavior?

The wave function describes the likely locations one will observe a particle. The wave function is governed by the Schrodinger Equation. That's the best you can do before you get into ambiguities and philosophies.

So hopefully you understand now that there is no ambiguity or philosophy in writing down a differential equation of motion for a point particle like I did earlier.

 

[reilly]

First off, the equation I wrote down is a sharp counterexample to your mistaken belief that the Schroedinger evolution is all that one can meaningfully talk about regarding the electron, because you think it is the only mathematically well-defined statement about its physics. Also you seem to not realize that the wave function is itself not an observable field, even in standard QM.

In the first place, BM (should actually be referred to as de Broglie-Bohm theory) is not just an "interpretation" of QM, but a different formulation of QM. It involves different equations than standard QM. And it is completely false to say that it is "not an accepted or even testable theory". No single formulation or interpretation of QM (including the textbook plus decoherence approach) is accepted as "the most correct" by most physicists; but physicists who have studied the pilot wave theory admit it is self-consistent and empirically equivalent to standard QM, even if they don't like it for whatever reason. As for it being testable, indeed it is for the possibility of quantum nonequilibrium dynamics:

Dynamical Origin of Quantum Probabilities
Antony Valentini and Hans Westman
http://eprintweb.org/S/authors/All/va/Valentini/12

De Broglie-Bohm Prediction of Quantum Violations for Cosmological Super-Hubble Modes
Antony Valentini
http://eprintweb.org/S/authors/All/va/Valentini/2

Inflationary Cosmology as a Probe of Primordial Quantum Mechanics
Antony Valentini
http://eprintweb.org/S/authors/All/va/Valentini/1

Furthermore, these are not my "own ideas", and the fact that you would characterize them like that as a way to dismiss them or refuse to acknowledge them tells me that you don't and are not really interested in understanding anything different from a naive textbook approach to QM.

The ball is in your court now. I gave you a sharp counterexample to your claims that pilot wave theory is not testable or "accepted", and it is up to you to show a dignified response.

I agree with peter0302, he's got it right,in spite of his alleged naivety and
I support his notions( in fact, if you read his posts, you'll find him to be quite sophisticated)
Dignified?, not to worry.

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: How about an example or two of an "naive textbook approach.

You want dignity in response to calling someone "naive"? Hmmm Am I missing something?
Regards,
Reilly Atkinson

 

[Maaneli]

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?

1. Yes.

2. Yes.

3. Yes.

4. No so clear yet if it gives us the same answers or something new.

You have to understand that throwing out specific examples like that is not a challenge to the alternate theory if you understand how that alternate theory works in the slightest. Also, I already referenced new predictions of pilot wave theory that the standard QM or QED cannot make. So there.

And I have to disagree with you about Peter's sophistication. He clearly refused to admit an alternative possibility that is just as mathematically rigorous as what he thinks.

 

[peter0302]

Well, I certainly appreciate the compliment Reilly, and especially coming from someone as knowledgeable as yourself that's means a lot. :)

As for Maaneli's comments, I certainly did not literally mean that the Schrodinger equation is the only mathematically correct QM equation. (I would have been remiss, for example, if I had ignored the Dirac equation or all of QED for that matter).

My point is that there is a stark difference between saying something "acts like a wave" and saying that a particle's probability density amplitude - i.e. wave function - is governed by the Schrodinger equation. One is a hueristic, the other is a mathematical statement. One conveys testable, reproducible information; the other conveys philosophy and ambiguity.

Regarding the DeBroglie-Bohm pilot wave hypothesis (aka Bohmian Mechanics), it is not a scientific theory any more than Intelligent Design is a scientific theory. Both purport to explain the observable phenomina. Neither can be tested (at this time) using the methods of science.

To state that evidence of a theory includes its ability to explain everything countermands the fundamental tenets of science itself. Anyone can sit down with a bottle of Jack and come up with an elaborate explanation for everything. That does not make it true. The measure of a theory is its ability to make accurate predictions, not to explain. Moreover, that the theory makes accurate predictions does not make it right - it merely makes it not wrong. In other words, science can merely rule out theories; it cannot prove them (ironically, all science can do is "prove negatives").

The inherent weakness of any quantum interpretation is that it, by definition, must account for all known results. Therefore, that Bohmian Mechanics, for example, can make the same predictions as QFT is not an argument in its favor. Show me an interpretation that explains everything else, and makes new predictions about things we haven't seen yet, that turn out to be right, and I'll be the first in line to support their Nobel nomination.

One slight exception that I will give you would be an Occam's razor-type argument, that is, if two competing interpretations are offered and one makes significantly fewer assumptions, than it is the more favorable view. However, no current quantum interpretation is clearly the winner in this respect (though some, like the Cramer TI idea, probably are clear losers).

That is how I justify my statement that all we can say about the behavior of the electron is that the location where we are likely to find it is governed by the wave function - and that any other statements are, at this time, not scientifically meaningful.

Now, not to be thought of as hypocritical, I frequently enjoy discussing the merits of various QM interpretations. For one thing, I, like many people, do indeed wish there was an explanation for what we see. Further, I hold out hope that some, if not many of the competing interpretations out there will eventually be mature enough to become genuine theories that make testable predictions. And, like anyone else, I enjoy a little bit of philosophy here and there.

*But* when I talk about an interpretation, I attempt to always do so in the _context_ of an interpretative discussion, and never to be making factual or scientific assertions. I probably have crossed the line sometimes, but I aim not to.

Maaneli, the reason I criticized your psots is because you do not seem to be attempting to make any kind of distinction between predictive science and philosophy/interpretation. Moreover, putting the DeBroglie-Bohm quantum potential formula out there as an example of what we can say the electron is doing before detection (which is how I interpreted your point) is misleading.

So, I stand by what I originally said and hope that I've persuaded you that your views on this matter contain more interpretive than scientific opinions.

 

[Maaneli]

Regarding the DeBroglie-Bohm pilot wave hypothesis (aka Bohmian Mechanics), it is not a scientific theory any more than Intelligent Design is a scientific theory. Both purport to explain the observable phenomina. Neither can be tested (at this time) using the methods of science.

OK, you just lost all credibility on this discussion by comparing deBB to ID, and in calling deBB a hypothesis and not a scientific theory. That would be like comparing textbook QM to ID. Regardless of what ID purports, it doesn't explain or predict ANYTHING. deBB theory on the other hand, explains and predicts everything in QM observed thus far. My guess is that you don't understand either deBB theory or ID. Also, it is clear that you did not bother to even look at the papers I cited as proof that deBB theory makes new predictions that are testable.

The inherent weakness of any quantum interpretation is that it, by definition, must account for all known results. Therefore, that Bohmian Mechanics, for example, can make the same predictions as QFT is not an argument in its favor.

That deBB field theory makes the same predictions as standard QFT is an argument for why it is at least as good to use as standard QFT. That is contrary to what many people think, yourself included it seems.

Show me an interpretation that explains everything else, and makes new predictions about things we haven't seen yet, that turn out to be right, and I'll be the first in line to support their Nobel nomination.

I did show you. Look at those damn papers I cited.

One slight exception that I will give you would be an Occam's razor-type argument, that is, if two competing interpretations are offered and one makes significantly fewer assumptions, than it is the more favorable view. However, no current quantum interpretation is clearly the winner in this respect (though some, like the Cramer TI idea, probably are clear losers).

I might agree with you here. But I hope we can agree that among competing interpretations, the CI interpretation is clearly the worst by an Occam's razor type argument, in comparison to pilot wave theory, GRW collapse theory, decoherence theory, stochastic mechanics, MWI, and others.

Further, I hold out hope that some, if not many of the competing interpretations out there will eventually be mature enough to become genuine theories that make testable predictions.

Look at those papers.

Maaneli, the reason I criticized your psots is because you do not seem to be attempting to make any kind of distinction between predictive science and philosophy/interpretation.

Yes I did make such a distinction.

Moreover, putting the DeBroglie-Bohm quantum potential formula out there as an example of what we can say the electron is doing before detection (which is how I interpreted your point) is misleading.

I wrote down the guidance equation NOT the quantum potential. Those are two different things, and the former is more fundamental than the latter in deBB theory.

So, I stand by what I originally said and hope that I've persuaded you that your views on this matter contain more interpretive than scientific opinions.

You haven't because you haven't understood my views in this matter in the first place.

I appreciate that you tried to explain yourself though.

 

[peter0302]

Well, as far as the papers you've posted, I don't know if they've been peer reviewed or published, but it looks to me like they haven't. There is so much misinformation out there that, frankly, yes, I don't bother to read things unless they're published, peer reviewed, and (often) explained by people here who understand the math much better than I. If they are indeed as groundbreaking as you say they are, surely they will change the course of physics.

Out of curiosity, are you Antony Valentini?

 

[Maaneli]

Well, as far as the papers you've posted, I don't know if they've been peer reviewed or published, but it looks to me like they haven't. There is so much misinformation out there that, frankly, yes, I don't bother to read things unless they're published, peer reviewed, and (often) explained by people here who understand the math much better than I. If they are indeed as groundbreaking as you say they are, surely they will change the course of physics.

Out of curiosity, are you Antony Valentini?

No I'm not Valentini. BTW, two of those papers were just posted in the past 3 months. But Valentini is highly respected in quantum foundations circles, is considered a world expert on pilot wave theory, has been a major player in the MWI vs Pilot wave theory debates, and is a former research associate at the Perimeter Institute on the support of Lee Smolin, and is now in the foundations and cosmology group with Dowker and Magueijo at the Imperial College. And yes he has published quite a few works. That should be sufficient for you to trust his credibility on this subject.

To be honest, I get the sense that you're trying to BS your way out of looking at those papers and admitting you made mistakes. You didn't even bother to admit your mistakes about your comments on the other thread.

 

[Maaneli]

Well, as far as the papers you've posted, I don't know if they've been peer reviewed or published, but it looks to me like they haven't. There is so much misinformation out there that, frankly, yes, I don't bother to read things unless they're published, peer reviewed, and (often) explained by people here who understand the math much better than I. If they are indeed as groundbreaking as you say they are, surely they will change the course of physics.

Out of curiosity, are you Antony Valentini?

Here.

http://www.fqxi.org/large-grants/awardee/details/valentini

http://www.perimeterinstitute.ca/in...task=view&id=30&Itemid=72&pi=Antony_Valentini

(go to week 12)
http://www.iqc.ca/~qipcourse/interpret/

 

[peter0302]

You're right, my intellectual capacity is clearly dwarfed by yours, so there's really no point in continuing.

 

[Maaneli]

You're right, my intellectual capacity is clearly dwarfed by yours, so there's really no point in continuing.

Well, if you say so, then I guess so!

 

[reilly]

To be honest, I get the sense that you're trying to BS your way out of looking at those papers and admitting you made mistakes. You didn't even bother to admit your mistakes about your comments on the other thread.

Let me denote Bohm's alternate Quantum Theory as BQT. Those of us of a certain age have been waiting 50 years for a big BQT breakthrough -- I first learned about BQT as a student in the late 1950s. No breakthrough; I stopped holding my breath quite a long time ago.The perception of little value created by BQT is strong, the physics community, in general, is skeptical, at best, of BQT's contributions to physics; few, if any, have seen any -- remember, I'm talking about perceptions. On the other hand,from superconductivity to the Standard Model, regular physics has made extraordinary progress in the lat 50 years.A suggestion: BQT is out of the mainstream oif physics, and is often dismissed within the physics community. BQT supporters have a massive sales job, and the market is indifferent. That is, you would do well, to convince peter0302, or me, or others looking at this thread, that there are clear and important benefits to reading the papers you suggest -- we all have plenty of other things to do. By the way, if you want to make a sale -- to get some of us actually reading -- do not insult nor demean your potential customers, as you do in the excerpt of yours quoted above.

By the way, you have yet to supply us with examples of textbook inadequacies

Do you have references for the computations you claim can be done in BQT ?

Regards,
Reilly Atkinson

 

[Maaneli]

Let me denote Bohm's alternate Quantum Theory as BQT. Those of us of a certain age have been waiting 50 years for a big BQT breakthrough -- I first learned about BQT as a student in the late 1950s. No breakthrough; I stopped holding my breath quite a long time ago.The perception of little value created by BQT is strong, the physics community, in general, is skeptical, at best, of BQT's contributions to physics; few, if any, have seen any -- remember, I'm talking about perceptions. On the other hand,from superconductivity to the Standard Model, regular physics has made extraordinary progress in the lat 50 years.A suggestion: BQT is out of the mainstream oif physics, and is often dismissed within the physics community. BQT supporters have a massive sales job, and the market is indifferent. That is, you would do well, to convince peter0302, or me, or others looking at this thread, that there are clear and important benefits to reading the papers you suggest -- we all have plenty of other things to do. By the way, if you want to make a sale -- to get some of us actually reading -- do not insult nor demean your potential customers, as you do in the excerpt of yours quoted above.

By the way, you have yet to supply us with examples of textbook inadequacies

Do you have references for the computations you claim can be done in BQT ?

Regards,
Reilly Atkinson

Reilly,

I appreciate your willingness to listen further. I'll answer your questions soon. But first I need to know where you are in terms of your knowledge of BQM (fair enough name). This will help me a lot in knowing where to start, and so that there aren't as many misunderstandings.

 

[reilly]

I really remember next to nothing, so I'm a beginner. I don't particularly want to do the computations, I'd just like to see them done.
Regards,
Reilly Atkinson

 

[kahoomann]

Let me denote Bohm's alternate Quantum Theory as BQT. Those of us of a certain age have been waiting 50 years for a big BQT breakthrough -- I first learned about BQT as a student in the late 1950s. No breakthrough; I stopped holding my breath quite a long time ago.The perception of little value created by BQT is strong, the physics community, in general, is skeptical, at best, of BQT's contributions to physics; few, if any, have seen any -- remember, I'm talking about perceptions. On the other hand,from superconductivity to the Standard Model, regular physics has made extraordinary progress in the lat 50 years.

Regards,
Reilly Atkinson

<<The perception of little value created by BQT is strong, the physics community, in general, is skeptical, at best, of BQT's contributions to physics;>>

"Niels Bohr brainwashed a whole generation of physicists into believing that the problem (of the interpretation of quantum mechanics) had been solved fifty years ago."-Murray Gell-Mann, Noble Prize acceptance speech, 1976

 

[Maaneli]

I really remember next to nothing, so I'm a beginner. I don't particularly want to do the computations, I'd just like to see them done.
Regards,
Reilly Atkinson

I really remember next to nothing, so I'm a beginner. I don't particularly want to do the computations, I'd just like to see them done.
Regards,
Reilly Atkinson

OK, Reilly, that's a very important admission. I should like to emphasize that most of the "mainstream" physicists who dismiss deBB theory are, like you, people who either have never studied the theory, or studied it so long ago that they forgot anything they knew. Then they assume that if there was anything too it, their colleagues (meaning the people they know, which is always a minutely small fraction, and not even a statistically representative sample, of the physicists in every subfield) would be all over it. Well, this is part of the problem. Ignorance begets false assumptions about what others know, and consequently indifference on their own part. Don't you think that it makes no sense to dismiss a theory without having any understanding about it? That is why I am happy that you seem to be willing to look into this. Also, try to distinguish two things: interpretational questions about a theory on the one hand, and the computational usefulness of a theory on the other. Just because a theory is computationally useful doesn't mean it is interpretationally transparent. The converse is also true. Nevertheless, with respect to deBB theory, it has indeed had distinct practical advantages, unbenknownst to many of the specialists who use those equations!

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. Also, BQM has recently become very popular among prominent theoretical physical chemists such as David Tannor and Robert Wyatt because it greatly computationally simplifies problems involving quantum tunneling in 3-D, and in computing scattering angles. There is also the fact that the theory gives a mathematically well-defined criterion for the quantum-classical limit, as you'll see. You will also see the newer work on Bohmian field theories that are empirically equivalent to standard QFT, which is why I answered yes to all your questions.

But the most important virtue of the theory is that it is the mathematically simplest solution to the measurement problem (which can be decomposed into two parts: the problem of definite outcomes and the preferred basis problem). If you don't understand what the measurement problem is, please just say so. That is the most important motivation for the theory. Here is my brief account of the measurement problem and how BQM does better than your "practical CI":

Deterministic formulations of QM (like BQM) have more explanatory power than the Copenhagen interpretation because the latter suffers from the measurement problems - it does not explain where and when the wavefunction "collapses" during an experimental process called a "measurement". In fact, the word measurement isn't even defined by Copenhagen other than a collapse of the wavefunction. For that matter, the Copenhagen interpretation is actually physically inconsistent because its wavefunction collapse postulate contradicts the linear, unitary, deterministic evolution of Schroedinger's equation for the wavefunction. The fact that the wavefunction collapse is a postulate also implies that the theory can never be apply to the physical world unless there is a physicist present to invoke the collapse postulate in a highly idealized laboratory experiment. So it is a highly anthropocentric theory. It does not apply to the physical world independently of humans. Let me also quote John Bell on this issue:

<< It would seem that the theory [quantum mechanics] is exclusively concerned about "results of measurement", and has nothing to say about anything else. What exactly qualifies some physical systems to play the role of "measurer"? Was the wavefunction of the world waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer, for some better qualified system ... with a Ph.D.? If the theory is to apply to anything but highly idealized laboratory operations, are we not obliged to admit that more or less "measurement-like" processes are going on more or less all the time, more or less everywhere. Do we not have jumping then all the time? >>

Related to this is the fact that the Copenhagen interpretation doesn't take into account environmental decoherence in the quantum state, nor does it provide an ontology for the quantum world which corresponds to the particle ontology of classical physics in the quantum-classical limit. Finally, the Copenhagen interpretation has to *postulate* the Born rule probability that P(x,t) = |psi(x,t)|^2. The deterministic theories of QM such as de Broglie-Bohm (deBB) on the other hand, the Schroedinger evolution always holds, and the appearance of collapse comes about because in a measurement interaction (which is just interference of two spatially separated coherent quantum states), the wavefunctions in initial linear superposition branch off from their superposition in configuration space, and the particle ends up in only one of those branching wavefunctions obeying Schroedinger's equation, while the others propagate away also according to Schroedinger's equation. For this reason, one can derive the phenomenological *appearance* of wavefunction collapse from the underlying deterministic particle dynamics, as well as the statistical formalism of operators yielding observables. It also naturally incorporates environmental decoherence, and provides a clear ontology for the quantum world which allows for a mathematically and ontologically precise definition of the quantum-classical limit. So this measurement theory works without any reference to humans or idealized laboratory experiments. Finally, the deterministic formulations like deBB can actually *derive* the Born rule probability distribution from standard arguments in statistical mechanics, rather than just assuming it as an initial condition. This last point actually suggests new physics. More precisely, the deBB theory does suggest that quantum probabilities have emerged as the equilibrium limit of a more general nonequilibrium quantum theory. There are proposed cosmological tests of this last claim, as I have already indicated and will do so again. Oh and a deterministic formulation like deBB can do all the above with fewer postulates. So you get all the same (and new!) physics with less assumptions.

Also now, please look at this decent article by Schlosshauer on the problems of measurement (first 9 pages):

Decoherence, the measurement problem, and interpretations of quantum mechanics
Authors: Maximilian Schlosshauer
http://arxiv.org/PS_cache/quant-ph/pdf/0312/0312059v4.pdf

Also, for sociological reasons, you should find these articles useful to read:

Quantum randomness may not be random
22 March 2008
From New Scientist
Mark Buchanan
http://groups.google.com/group/alt.philosophy/browse_thread/thread/31b8c1658e7c4e7a/ebfdbc782e24ea7d

Why isn't every physicist a Bohmian?
Authors: Oliver Passon
http://arxiv.org/abs/quant-ph/0412119

Would Bohr be born if Bohm were born before Born?
Authors: H. Nikolic
http://arxiv.org/abs/physics/0702069

 

[Maaneli]

I really remember next to nothing, so I'm a beginner. I don't particularly want to do the computations, I'd just like to see them done.
Regards,
Reilly Atkinson

Now for the actual theory, before I show you the field theoretic version, you have to first get a grasp of the basic nonrelativistic and relativistic versions of 1st quantized deBB theory. There are many clear and concise treatments of it so that I do not have to reinvent the wheel. For this reason, please carefully read the relevant sections of the following two papers:

(The first 11 pages of this)
What you always wanted to know about Bohmian mechanics but were afraid to ask
Authors: Oliver Passon
Invited talk at the spring meeting of the Deutsche Physikalische Gesellschaft, Dortmund, 2006. Forthcoming in Physics and Philosophy. Physics and Philosophy 3 (2006).
http://arxiv.org/PS_cache/quant-ph/pdf/0611/0611032v1.pdf

Also have a look at this shorter review paper:

(Week 5 of the Perimeter Institute Interpretation of Quantum Mechanics Lecture Course series):
http://www.iqc.ca/~qipcourse/interpret/lectures/lec-09-10-dBB.pdf
http://www.iqc.ca/~qipcourse/interpret/

Once you have read them, please let me know if you understand these basics. It would be of no use to show you the field theoretic version, if the basics are not clear to you.

 

[ZapperZ]

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.

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?

BTW, please limit your citations to ONLY peer-reviewed papers. If those arXiv papers have been published already, please also include the exact reference along with the arXiv links if such information isn't included with the arXiv links.

Zz.

 

[Maaneli]

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?

BTW, please limit your citations to ONLY peer-reviewed papers. If those arXiv papers have been published already, please also include the exact reference along with the arXiv links if such information isn't included with the arXiv links.

Zz.

All the arxiv links I cite already have the journal references in them. But, I added them separately above anyway.

I'll answer your other questions tomorrow.

 

[ZapperZ]

All the arxiv links I cite already have the journal references in them. But, I added them separately above anyway.

Thanks, that would make it more convenient. If it is part of a "conference" or "speech" by a well-known figure, the references would not be necessary since those are often not published.

Zz.

 

[Maaneli]

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?

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":

http://relativity.livingreviews.org/Articles/lrr-2005-12/

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. Notice also that they call equation 194 the "so-called quantum potential". And notice also the interesting application of this formulation! They are deriving a GR analogue model from these equations of a BEC!

By the way, if you don't know at all what the equations of BQM look like, just have a look at the papers I cited in my previous posts and you'll immediately see the obvious correspondence. I always am amused when at Stony Brook University, I tell my profs like Dominik Schneble (runs the BEC lab at Stony Brook) or Sasha Abanov (condensed matter theorist) that they use the equations of a "hidden variables" formulation of QM. They have a stunned look on their face, LOL.

And if you're still in disbelief (which you shouldn't be by now), just have a look at the original papers of de Broglie and Bohm:

Quantum Theory at the Crossroads: Reconsidering the 1927 Solvay Conference (page 46)
Guido Bacciagaluppi and Antony Valentini
(Draft of a book published by Cambridge University Press)
http://eprintweb.org/S/authors/All/va/Valentini/6

A Suggested Interpretation of the Quantum Theory in Terms of "Hidden" Variables. I
David Bohm
http://prola.aps.org/abstract/PR/v85/i2/p166_1

Let me know if you're still not convinced.

 

[Maaneli]

Thanks, that would make it more convenient. If it is part of a "conference" or "speech" by a well-known figure, the references would not be necessary since those are often not published.

Zz.

One other amusing observation. On page 21-13 of Feynman's lectures volume III, Feynman says

"It says [equation 21.38] that the acceleration of each particle of the fluid whose charge is q comes from the ordinary Lorentz force q(E + v*cross(B)) plus an additional force, which is the gradient of some mystical quantum mechanical potential - a force which is not very big except at the junction between two superconductors."

 

[akhmeteli]

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.

I am afraid I am nit-picking again, but Madelung could not do it in 1924 for the simple reason that the Schroedinger equation was published in 1926. The Madelung's article was actually published in 1927 (Z. Phys. 40, 322)

 

[Maaneli]

I am afraid I am nit-picking again, but Madelung could not do it in 1924 for the simple reason that the Schroedinger equation was published in 1926. The Madelung's article was actually published in 1927 (Z. Phys. 40, 322)

Actually, the Madelung article was published in 1926. de Broglie's article was published in 1927. My mistake.

 

[reilly]

OK, Reilly, that's a very important admission. I should like to emphasize that most of the "mainstream" physicists who dismiss deBB theory are, like you, people who either have never studied the theory, or studied it so long ago that they forgot anything they knew. Then they assume that if there was anything too it, their colleagues (meaning the people they know, which is always a minutely small fraction, and not even a statistically representative sample, of the physicists in every subfield) would be all over it. Well, this is part of the problem. Ignorance begets false assumptions about what others know, and consequently indifference on their own part. Don't you think that it makes no sense to dismiss a theory without having any understanding about it? That is why I am happy that you seem to be willing to look into this. Also, try to distinguish two things: interpretational questions about a theory on the one hand, and the computational usefulness of a theory on the other. Just because a theory is computationally useful doesn't mean it is interpretationally transparent. The converse is also true. Nevertheless, with respect to deBB theory, it has indeed had distinct practical advantages, unbenknownst to many of the specialists who use those equations!

You really did not read my post, or you failed to understand my suggestions how to overcome your problem is that BQM registers 0 on the Richter scale.

Quite the contrary to what you claim about word-of -mouth communication of new ideas is demonstrably false(big literature). It can be highly successful. The work of Einstein, Bohr, and Feynman got spread that way.

That's the point: 50 years ago there was some sympathy to Bohm's ideas, but it's pretty much dead; nothing ever happened with BQM. There was no word-of-mouth info to transmit.Why, then, should I read all those papers? If there are solid, demonstrable reasons to do so, maybe. But first,

Please tell how to find the computations I want to see. I'll take the chance that I can probably work my way through whatever is there. If not I'll ask questions.

Regards,.
Reilly Atkinson

 

[akhmeteli]

Actually, the Madelung article was published in 1926. de Broglie's article was published in 1927. My mistake.

I know for some reason the Madelung's article is often quoted as published in 1926. However, it was actually published in 1927.

http://adsabs.harvard.edu/abs/1927ZPhy...40..322M

http://www.springerlink.com/content/100378/?sortorder=asc&p_o=1540

 

[Maaneli]

I know for some reason the Madelung's article is often quoted as published in 1926. However, it was actually published in 1927.

http://adsabs.harvard.edu/abs/1927ZPhy...40..322M

http://www.springerlink.com/content/100378/?sortorder=asc&p_o=1540

Hmm, interesting. I was getting 1926 from Wallstrom's 1994 Phys. Rev. paper. Good to know though. Thanks.

 

[Maaneli]

You really did not read my post, or you failed to understand my suggestions how to overcome your problem is that BQM registers 0 on the Richter scale.

Quite the contrary to what you claim about word-of -mouth communication of new ideas is demonstrably false(big literature). It can be highly successful. The work of Einstein, Bohr, and Feynman got spread that way.

That's the point: 50 years ago there was some sympathy to Bohm's ideas, but it's pretty much dead; nothing ever happened with BQM. There was no word-of-mouth info to transmit.Why, then, should I read all those papers? If there are solid, demonstrable reasons to do so, maybe. But first,

Please tell how to find the computations I want to see. I'll take the chance that I can probably work my way through whatever is there. If not I'll ask questions.

Regards,.
Reilly Atkinson

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.

Now, I already gave you a paper where you can find the basics of the BQM formalism. So, before you can understand why the field theoretic extensions work, it is really important to understand the subtleties of the basics. Most importantly, to understand why and how BQM is empirically equivalent to textbook nonrelativistic and relativistic QM. That will indirectly answer your other questions about why pilot wave field theory does everything in QED you're asking for. So, again, please at least have a look at these two papers which I spent the time to select for you. They're not that long or difficult to understand:

(The first 11 pages of this)
What you always wanted to know about Bohmian mechanics but were afraid to ask
Authors: Oliver Passon
Invited talk at the spring meeting of the Deutsche Physikalische Gesellschaft, Dortmund, 2006. Forthcoming in Physics and Philosophy. Physics and Philosophy 3 (2006).
http://arxiv.org/PS_cache/quant-ph/p.../0611032v1.pdf

(Week 5 of the Perimeter Institute Interpretation of Quantum Mechanics Lecture Course series):
http://www.iqc.ca/~qipcourse/interpr...-09-10-dBB.pdf
http://www.iqc.ca/~qipcourse/interpret/