Classical Atom Models: A Nobel Prize Waiting to be Won?

[reilly]

Anybody who can explain the details of atomic spectra by classical means will win a Nobel. Particularly, 100 years ago, quite a few have tried to build classical models of the atom, all without success. In the meantime we've put semiconductors and lasers, quantum devices both, radioactivity and nuclear magnetic resonance to work, ... The odds for a classical rebirth look pretty slim.

Regards,
Reilly Atkinson

 

[Careful]

Anybody who can explain the details of atomic spectra by classical means will win a Nobel. Particularly, 100 years ago, quite a few have tried to build classical models of the atom, all without success. In the meantime we've put semiconductors and lasers, quantum devices both, radioactivity and nuclear magnetic resonance to work, ... The odds for a classical rebirth look pretty slim.

Regards,
Reilly Atkinson

Ah, Roman greek classicism came also back after the middle ages; who would have made a bet on that in 1500 ? It is unrealistic to think that realism is sacrified in one century, on the other hand the number of science fiction freaks is growing steadily every day

 

[vanesch]

Let's have the "new classicists" discussion here, about the possibility of reproducing QM results with classical, or neo-classical theories. Let's refrain from scattering these discussions in other threads (if you think it useful to do so, post a small reference in the other threads to this one).

 

[member 11137]

Oh don't be afraid: I shall not be this one who will make CM revival. No, I just wanted to ask: what is for you exactly the boarder between classical and not classical (quantum)? Is it the introduction of the h number (Planck), the discovery of scattering, ...? Is it "just" a technical and mathematical procedee applied to classical theories? Is it the fundamental discovery that phenomenon at very small scala are not continuous? ...

 

[vanesch]

Oh don't be afraid: I shall not be this one who will make CM revival. No, I just wanted to ask: what is for you exactly the boarder between classical and not classical (quantum)?

The superposition principle.

 

[Careful]

The superposition principle.

I agree here, the introduction of nonlinear interactions as mutiplication operators and thereby keeping the wave equation linear is definately something incomprehensible from a classical point of view. Also, the fact that a multiparticle Schroedinger wave lives *essentially* on configuration space is unacceptable from a spacetime point of view. The Planck number is NOT something ``quantal´´ in the sense that it is just a phemenological scale which is put in by hand in the theory (you can do the same in classical physics). Also scattering has (semi) classical analoga. By the way, QM does not say at all that phenomena on the small scale are not continuous (as long as you do not invoque reduction). It only says that measurable quantities usually have discrete spectra; but a similar phenomenon could be achieved in a classical theory where phase space is partitioned in a ``free´´ part (continuous spectrum) and a discrete set of stable attractors (note that you have to include radiation degrees of freedom here) with very small transition times between different domains of attraction.

 

[DrChinese]

No, I just wanted to ask: what is for you exactly the border between classical and not classical (quantum)?

What about the Uncertainty Principle? I have seen attempts to model it from classical principles (I'm not sure any successfully); but I personally don't really think it is classical at its base.

 

[RandallB]

The superposition principle.

That does seem to be key.
The areas beyond the border into the QM domain can be explained away in the classical as unreadable because of the A) the lack of tools to make the needed precise measurements required, and/or B) the need to find and understand the “unknown variable” that would allow for a precise interpretation of measurements when “it” is included.

QM experiments that seem to show proof of its correctness can be explained as statistical conveniences that mathematical predict averages. But the prediction of averages alone does not mean an understanding of reality or a proof.

Thus for QM it is the “superposition principle” is the part that offers a demonstration that QM can understand reality. Understanding superposition is the key to completing the view of reality within QM. It’s the concept of superposition that best explains the behavior of a particle, like and electron in ‘orbit’ or ‘being’ around a proton.
But from the CM view this can rightly be considered just a successful and workable mathematical statistical convenience, not proof.
And again in the double slit experiment that only shows statistically accumulated evidence that explained by superposition. CM can legitimately claim that this does not give a proof to superposition, only that it can provide an interpretation that fits the statistics. CM could do as well or better if only it could find the “unknown” variable, guide particle, guide wave or whatever that could classically define the results. These could be possible as yet undiscovered parts of real physics.

Thus the key to revival of CM would be finding the unknown “whatever” that would provide those solutions. So the task would seem clear as to what CM needs to find. QM has no way to prove QM correct over CM as its results will always be statistical.

But QM has taken another approach, by attempting to prove that any search for the needed CM “unknown” would fail. That is to prove a negative. First ‘proven’ by Johnny von Newman his math was shown to be “absurd” by John Bell in the 60’s. In its place he proposed his Bell Theorem that he hoped would show the way to the Einstein “unknown variable” and revive CM. Although another statistical proof, when tested experimentally it seems to show Bells hopes were misplaced and the idea of an “unknown variable” might be unworkable.

The application of Bell to the entanglement experiments both by polarization and “Stern-Gerlach” devices are the only experiments that tend to “Prove” the “unknown variable” as untenable. And by implication, as the only viable idea remaining, that superposition must be correct.

Advise me of any others, but as far as I know this is the only “proof” of superposition and therefore QM.

So it seems to me the first step for revival of CM is finding that “unknown”.
Or at a minimum demonstrating that the one and only negative proof against CM, and that the “unknown” could be real, is somehow flawed.
Which would imply “superposition” could be wrong.

 

[Careful]

The application of Bell to the entanglement experiments both by polarization and “Stern-Gerlach” devices are the only experiments that tend to “Prove” the “unknown variable” as untenable. And by implication, as the only viable idea remaining, that superposition must be correct.
Advise me of any others, but as far as I know this is the only “proof” of superposition and therefore QM.
So it seems to me the first step for revival of CM is finding that “unknown”.
Or at a minimum demonstrating that the one and only negative proof against CM, and that the “unknown” could be real, is somehow flawed.
Which would imply “superposition” could be wrong.

Your exposition seems fair to me here. Only some comments concerning the Bell theorem. The perfect separablility is *not* a necessary hypothesis from the local realist point of view, albeit a *reasonable* one in practical setups where the dectors are far enough separated from one another (say a distance > one meter).
Moreover, there are many Bell inequalities which result from this hypothesis, the weakest one (and never violated in any experiment where the separability assumption is *tenable*) being the Clauser Horne 74 inequality. But, as you might have seen in previous threads, the discussion always amounts to ``everyone has his own taste´´ (citation from ``Die Fledermaus´´ ). If you dismiss taste and don't bother about the argument ``QM did so much for us´´ (except the nasty cat which some would prefer to die) then Bell tests provide no proof whatsoever for now against local realism. If they would one day be perfect (and the QM prediction comes out), then one knows finally that atoms are smart, remember their past and can anticipate what the dectors are going to do. This is actually what QM tells us if you want to give a ``realist´´ interpretation to its outcome.

 

[vanesch]

Thus for QM it is the “superposition principle” is the part that offers a demonstration that QM can understand reality. Understanding superposition is the key to completing the view of reality within QM. It’s the concept of superposition that best explains the behavior of a particle, like and electron in ‘orbit’ or ‘being’ around a proton.
But from the CM view this can rightly be considered just a successful and workable mathematical statistical convenience, not proof.

I agree entirely with your analysis. However, it is often the property of a "principle" not to be demonstrable by "direct evidence". General covariance is also not demonstrable as one can always fix up an ether theory with the same predictive value. The true value in a principle lies in its ability to guide a theoretical construction, as a unifying idea, not so much in its direct observability.

Thus the key to revival of CM would be finding the unknown “whatever” that would provide those solutions. So the task would seem clear as to what CM needs to find. QM has no way to prove QM correct over CM as its results will always be statistical.

I think that's the real point. It is a matter of "taste", "belief", ... to find out whether or not one can spend time and effort looking for that "unknown whatever" in a CM that would give us the same results (at least those that HAVE been verified experimentally) as QM. One shouldn't crucify people wanting to do so, but it should also be accepted that certain people "believe" that such efforts are quite vain. This is a matter of personal taste. The only observation is, that today, we have no such theory.

But QM has taken another approach, by attempting to prove that any search for the needed CM “unknown” would fail. That is to prove a negative. First ‘proven’ by Johnny von Newman his math was shown to be “absurd” by John Bell in the 60’s. In its place he proposed his Bell Theorem that he hoped would show the way to the Einstein “unknown variable” and revive CM. Although another statistical proof, when tested experimentally it seems to show Bells hopes were misplaced and the idea of an “unknown variable” might be unworkable.
The application of Bell to the entanglement experiments both by polarization and “Stern-Gerlach” devices are the only experiments that tend to “Prove” the “unknown variable” as untenable. And by implication, as the only viable idea remaining, that superposition must be correct.

I think that the attempt to "prove a negative" is somehow a vain effort. I think we should consider Bell's theorem as interesting challenges to QM: they indicate where it is interesting to TEST QM to experiment. But the whole class of LR CM theories is too vaguely defined to be eliminated without ever leaving a small loophole - with enough sophistication, one will always invent a way to explain away THIS experiment. So I don't see these tests as definitive exclusions of whatever class of theories. I only see them (until contradiction) as further indirect experimental confirmations of QM (and hence of its underlying ideas). Each of these experiments provides also further constraints on a possible CM theory.

So it seems to me the first step for revival of CM is finding that “unknown”.
Or at a minimum demonstrating that the one and only negative proof against CM, and that the “unknown” could be real, is somehow flawed.
Which would imply “superposition” could be wrong.

Well, I would first like to *see* a CM theory that can reproduce QM results. Until then, I'm not really interested in it. There *are* some interesting partial results, in some domains, like SED. So I can understand that some people want to look for it.

 

[RandallB]

... Bell .. proof ... If .. one day perfect, then one knows finally that atoms are smart, remember their past and can anticipate what the dectors are going to do. This is actually what QM tells us if you want to give a ``realist´´ interpretation to its outcome.

I disagree on this point.
It isn’t fair to expect a “realist view” of QM as they are by design different things. So IF a “perfect” QM proof could one day be found, it would not show that atoms remember their past. Rather it would confirm some QM theory that allows that past ‘here’ to be irrelevant. Maybe where another dimension is real with it own ‘history’ thus the two separating partials could remain ‘together’ in that dimension with no change in history there. But when ANY interaction takes place with either particle they then separate to develop there own histories in that other dimension. The point being, the interaction could only change one of the particles – thus they have identical histories up to and including the start position for that interaction on only one of them. In the history of our dimension the other particle would remain identical to or at least within strict correlation with that starting position but not be affected by the interaction in the least, and it would not matter at all if the unaffected particle was in the past or future in our dimension.

True that may look like memory, but memory would not be what QM is ‘telling us’.

But this is not this thread is about. More to the point here, do I believe that QM we can expect someday to see a “perfect” proof for QM? Actually I believe the design of QM demands that it can never do so, mostly because I don’t believe in that ‘other dimension’ I just mentioned. However there are 100’s of physicists searching for extra dimensions that if they can provide such proof would change my world view a lot. To show that this search was pointless in a clear CM argument could potentially save or redirect a lot of valuable resources.

Thus more than the point vanesch makes that CMers shouldn’t be crucified, I think the CM area should be given at least some small fair share of encouragement.

 

[RandallB]

I think that the attempt to "prove a negative" is somehow a vain effort. I think we should consider Bell's theorem as interesting challenges to QM:
….. experiments provide .. constraints on a possible CM theory.

Good point, I think too much has been made of the “negative proof” that CM cannot work. A better focus for CM is to look at the constraints the many experiments provide as data and guide posts to better focus a complete CM or any solution with.

I also note that reilly in opening this thread did offer some encouragement to the CM crowd by declaring that if properly successful they will win a Nobel Prize. Or at least he’d use his influence to see that it was so.

I think that comes with about $50,000 or more.
How about we find a little more for it. Presuming the successful CM approach is complete enough to fully explain the strong force it would most likely mean proving “Yang-Mills” wrong.
Now there is a $1,000,000 prize from the Clay Math Millennium problems to prove it correct. But the stringent rules at ClayMath.org/millennium also point out that an altranate proof (showing Yang-Mills wrong) would also qualify. (For the math wiz’s they also have six more problems)

Now there’s a little more encouragement.
Anybody know of any more “encouragement” out there being offered.
Heck I’ll kick in a couple bucks, if the result brings a legit TOE even if it’s not CM.
RB

 

[member 11137]

The superposition principle.

Following this very clever indication I have red the pages devoted to this principle in Tannoudji Diu and Laloe ... and discovered that it plays a very important role, given us the pragmatic possibility to understand the difference between statistic and quantum theory;well. But I also learned that it stays on two requisites: a) the Schrödinger equation which is linear and homogen; b) the fact that the space of states is a vector space.
Do you know if this picture holds for other representations of the quantum theory (Heisenberg, Dirac or interaction representation, ...)?
The spinor theory allows the formulation of a lot of Dirac's relations; the actual research tries to incorporate the notion of spin inside a Riemanian geometry; so, does this superposition principle exist and hold in such a context? I mean with this if the space of states is no more a vector space, what happens? Is it a science-fiction representation?

 

[member 11137]

... Each of these experiments provides also further constraints on a possible CM theory.
Well, I would first like to *see* a CM theory that can reproduce QM results. Until then, I'm not really interested in it. There *are* some interesting partial results, in some domains, like SED. So I can understand that some people want to look for it.

I agree with this suggested way of doing; CM needs first a plausible scenario that allows a correct description of QM predictions. Some people try to do it via the statistics but the principle of superposition is exactly the principle that explain the limit of the statistical approach; so it must not be the good one or at least, it must be completed with something else. I see QM more as a pragmatical and successful modern approach and CM as a more philosophical one. QM makes good predictions, CM tries to give us a deep description of "how are the things, how do they work really". Both are complementary ways of thinking and doing. I think we actually need a mental representation of what really happens at quantum scala in a classical way of thinking. Here lies the key.

 

[member 11137]

In this sense we could state that physical phenomenon arise with a certain probability inside a fixed underground topology and consider these phenomenon as quantum behaving;
or that these same but classical phenomenon arise with this given probability because the underground topology is permanently changing and only statisticly presenting a given configuration ... forcing them to behave as we can observe them ...
it is a question of relativity, of point of view, ...

 

[CarlB]

Also, the fact that a multiparticle Schroedinger wave lives *essentially* on configuration space is unacceptable from a spacetime point of view.

If you put QM into the QFT form in the position representation, the configuration space becomes trivial. That is, a position representation creation or annihilation operator is only nonzero at a single point in spacetime.

From this point of view, the momentum representation is just a useful mathematical trick.

What I'm saying here is that the QFT position representation is ontological and the others are just useful mathematical methods for calculation. Any reason why this is unacceptable?

Carl

 

[Careful]

If you put QM into the QFT form in the position representation, the configuration space becomes trivial. That is, a position representation creation or annihilation operator is only nonzero at a single point in spacetime.
From this point of view, the momentum representation is just a useful mathematical trick.
What I'm saying here is that the QFT position representation is ontological and the others are just useful mathematical methods for calculation. Any reason why this is unacceptable?
Carl

? Configuration space in QFT in the *Schroedinger* picture (in the canonical free field approach) consists of *all* field configurations on a slice of your favourite foliation. The Schroedinger wave essentially entangles field configurations at different (even relatively spacelike) space time locations.

 

[Sherlock]

The superposition principle, the wave equation, wave functions, harmonic oscillators and resonance, etc.-- all of these indicate a similarity to classical wave phenomena which continually evolve but are trackable in a way that quantum phenomena aren't trackable.


The terms that are used to qualitatively describe quantum phenomena all come from our macroscopic experience. But a *qualitative* picture of the essentially wavelike quantum phenomena is necessarily incomplete, because in order to 'see' quantum phenomena, they must be made to interact with macroscopically identifiable and manipulable instruments. This necessarily renders quantum phenomena 'discrete' and 'particulate' and 'random' as far as our perceptual apprehension is concerned. This is *necessary* because of limitations regarding the behavior of macroscopic instruments.

Quantum theory was made as classical as it could be made without sacrificing internal consistency and consistency with experimental results. For those who think that qm could now (apparently because much more is known now than was known several generations ago) be made even more classical, then the question is what exactly can be changed in qm to make it more classical?

Or, are the limitations that caused qm to be developed as it was still in effect?

 

[ZapperZ]

The superposition principle, the wave equation, wave functions, harmonic oscillators and resonance, etc.-- all of these indicate a similarity to classical wave phenomena which continually evolve but are trackable in a way that quantum phenomena aren't trackable.
The terms that are used to qualitatively describe quantum phenomena all come from our macroscopic experience. But a *qualitative* picture of the essentially wavelike quantum phenomena is necessarily incomplete, because in order to 'see' quantum phenomena, they must be made to interact with macroscopically identifiable and manipulable instruments. This necessarily renders quantum phenomena 'discrete' and 'particulate' and 'random' as far as our perceptual apprehension is concerned. This is *necessary* because of limitations regarding the behavior of macroscopic instruments.
Quantum theory was made as classical as it could be made without sacrificing internal consistency and consistency with experimental results. For those who think that qm could now (apparently because much more is known now than was known several generations ago) be made even more classical, then the question is what exactly can be changed in qm to make it more classical?
Or, are the limitations that caused qm to be developed as it was still in effect?

I have noticed several of these discussions going on in a number of threads, i.e. the apparent "validity" of classical description, and the idea that you cannot observe directly the manifestation of quantum phenomena. At the risk of exposing my utmost annoyance of such claims, I will try to point out a very obvious 90000-pound gorilla that almost everyone seems to have ignored - SUPERCONDUCTIVITY.

I will cite a paragraph from Carver Mead's PNAS paper[1] that says:

Although superconductivity was discovered in 1911, the recognition that superconductors manifest quantum phenomena on a macroscopic scale came too late to play a role in the formulation of quantum mechanics. Through modern experimental methods, however, superconducting structures give us direct access to the quantum nature of matter. The superconducting state is a coherent state formed by the collective interaction of a large fraction of the free electrons in a material. Its properties are dominated by known and controllable interactions within the collective ensemble. The dominant interaction is collective because the properties of each electron depend on the state of the entire ensemble, and it is electromagnetic because it couples to the charges of the electrons. Nowhere in natural phenomena do the basic laws of physics manifest themselves with more crystalline clarity.

I will point out that there have been ZERO attempt at trying to describe this phenomenon classically. NADA. Zilch! With the existence of high-Tc superconductor, classical mechanics seems to have thrown up its hand up in the air and gave up. It has no hope of describing the phase diagram of the cuprates superconductors, and even less of a hope to describe the pairing symmetry of the Cooper pairs, especially the spontaneous current that emerges out of the phase of the order parameter[2].

I have always maintain that the most convincing and evident demonstration of QM phenomena does not come from some esoteric experiments. They come from very familiar and reproducible experiments on condensed matter physics/material science. Unfortunately, the familiarity and "mundane" access of such experiments, and the fact that these are not "sexy" areas of physics made many people overlook the fact that these are QM phenomena staring right in their faces. People who dismiss QM always seem to want to tackle the "Schrodinger Cat", the "Bell-type experiments", etc.. etc. by producing alternative description that allows plenty of weasel room. NONE of them have ever attempted to describe superconductivity with the same accuracy and agreement as the BCS theory, for example, reproducing ALL of its predictions.

Until such a time when classical physics can produce a First Principle derivation of superconductivity, I will not be convinced that there is an "alternative" to QM.

Zz.

[1] C. Mead, PNAS v.94, p.6013 (1997); or http://www.pnas.org/cgi/content/abstract/94/12/6013?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=CARVER+MEAD&searchid=1132583573016_3544&stored_search=&FIRSTINDEX=0&journalcode=pnas

[2] D.J. Van Harlingen Rev. Mod. Phys. v.67, p.515 (1995).

 

[DrChinese]

[1] C. Mead, PNAS v.94, p.6013 (1997); or http://www.pnas.org/cgi/content/abstract/94/12/6013?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=CARVER+MEAD&searchid=1132583573016_3544&stored_search=&FIRSTINDEX=0&journalcode=pnas

For the above ref in PDF format, try: Our model system is a loop of superconducting wire...Correspondence limits based on classical mechanics are shown to be inappropriate.

As ZapperZ points out so well, it is not really fair to say the Classical (and Sem-classical) theories haven't had their day in court. They have. Even when alternative hypotheses are presented by respected scientists, they are often critiqued and found to come up short. And the one critical piece is ALWAYS missing: a useful new prediction. Please note that QM is still making useful NEW predictions every day - 75 years after introduction. I would like to see someone start with their alternative hypothesis and derive a useful new prediction.

 

[vanesch]

I will point out that there have been ZERO attempt at trying to describe this phenomenon classically. NADA. Zilch!

The discussion is, unfortunately, not about what an existing classical theory has to say about it (hence risking falsification) but whether the hope that a future "classical" theory might one day do so, is totally vain or simply tiny but existing.

Nevertheless I'm curious what LR proponents have to say about it - although I can guess it: "a full non-linear field equation solution for something as complicated as a solid is totally out of the question given that it is even not well known for two "particles". So anything potentially goes as we can't do the calculation. Who knows that "superconductivity" is not a solution of these complicated non-linear equations ?"

That's why I pointed to a much more modest and probably more tractable "classical" calculation: configuration interaction in quantum chemistry, on simple molecules (or even: the argon or neon spectrum!).
Effective field theory IS what you'd expect a classical field solution to come up with (if there's a way for the different "particles" not to merge into one big blob). But configuration interaction is a sheer product of entanglement. However, because these corrections are relatively small (although very well measurable), they can still be dismissed as "well, maybe it is a GR effect we didn't take into account".

As I said elsewhere, there's no need to crucify people who cling still on that tiny hope - after all they might think of challenging experiments - but I think that as long as they don't come up with something a bit more elaborate than SED which reproduces a bit more QM results before getting interested.

 

[QMrocks]

Also, how QM prediction of simple semiconductor bandstructure and its experimental verification is already phenomenal. There's very remote chance one can reproduce those bunch of curves with one equation

And the very reason is that QM is inherently a model for describing probabilistic outcomes makes it very versatile. Things of this nature (anything which we are absolutely ignorant of unless we measure it ) can most probably be tackled by QM. In fact QM model is so versatile that it was being applied to new field of studies remote from physics such as consciousness and finance. Not sure if this speaks well of QM.. but it sure does give people the hint that QM is nothing more than a tool for statistic.

 

[RandallB]

I see . . . CM as a more philosophical one (approach).
I think we actually need a mental representation of what really happens at quantum scala in a classical way of thinking.

So that means seeing CM as NOT philosophical but as real.

the question is what exactly can be changed in qm to make it more classical?

No: If the CM approach is to be done seriously it must reject superposition as a correct solution. Once rejecting that, it must reject QM as being the “correct path” as Einstein did in the 1920’s.
Now assuming that it would be folly to attempt to do the work by transforming QM into something “CM” How could you avoid bring along whatever it is you’ve assumed to be wrong? Einstein saw this early on so he spent a lifetime on QT as it was prior to QM and trying to combine with GR. But I don’t think that was a CM effort. Since GR by replacing three dimensions with four is not truly classical.

. The question becomes; just where does a CM solution start from? Assume the popular current superposition paths are dead ends. That may be the biggest problem with most CM approaches, they to often start from positions that have superposition already embedded in their background assumptions. I don’t think CM can expect to be successful using that approach, a completely new perspective needs to be used.

 

[DrChinese]

The discussion is, unfortunately, not about what an existing classical theory has to say about it (hence risking falsification) but whether the hope that a future "classical" theory might one day do so, is totally vain or simply tiny but existing.

1. I do not think SED is falsifiable to its adherents.

2. There really is no SED as a single theory - it is a morphing concept that has a single purpose - and that purpose has no use by definition. SED is an ad hoc theory intended to mimic QM while rejecting one or more quantum mechanical concepts. The author's only objective is to restore to theory the classical notion of determinism at a fundamental level while seeing indeterminism arise from the stochastics. This objective is also true of Bohmian Mechanics, which takes a different path.

3. Most scientists do not believe that a local realistic theory such as SED can exist. It is incompatible with Bell's Theorem, and for many that is enough to exclude it a priori. And logically, given the SED program, it should be obvious that SED is doomed to fail if you accept Bell's Theorem - you don't need an experiment ("loophole-free" or not) at all to tell you this.

4. Why should any theory be given credit before it delivers? For that matter, why should any theory be given credit before it shows any promise? SED holds out absolutely NOTHING at the end of the rainbow. If it succeeds, we will have QM. That story would be different IF it offered us something. For example, string theory at least promises a unification of GR and QFT as its premise - and that is clear and compelling!

So I guess it goes without saying that I personally am in the "SED has no promise" camp.

I realize that you want to be conciliatory to those with a differing viewpoints. (I hope my own cock-eyed ideas don't get reamed either. ) But there ARE good reasons why more efforts are not expended on research into alternative interpretations/explanations of QM's results. Careful strongly supports the SED program; you support the MWI program (and are a fine and reasonable advocate I might add!); ttn strongly supports the BM program. Each of you might feel there should be more research into a particular area because it shows promise. OK, fine, maybe you are right (small chance of breakthrough) - and I don't think anyone wants to stifle research anyway. Yet each of you should be able to easily acknowledge that there are conceptual difficulties with this position - SED, BM and MWI all go in completely different directions! How can they all have equal promise?

 

[ZapperZ]

The discussion is, unfortunately, not about what an existing classical theory has to say about it (hence risking falsification) but whether the hope that a future "classical" theory might one day do so, is totally vain or simply tiny but existing.

But this is nothing but speculation. People who cling to such hopes should realize it for what it is. You can't use unverified speculation to go against something that has been verified.

My point is that based on existing classical theory and philosophy, I see zero indication (not just small, but ZERO) of its ability to even come close to describing the superconductivity phenomenon. The idea of long-range phase coherence of charge carriers is not only difficult, but it is a non-existing concept in classical mechanics. And I haven't even brought in the issue of David Pine's "Quantum Protectorate". Again, these are extremely robust observations from condensed matter that blatantly defy classical descriptions. It is there, for all to see. It is just that not many people are aware of it.

As I said elsewhere, there's no need to crucify people who cling still on that tiny hope - after all they might think of challenging experiments - but I think that as long as they don't come up with something a bit more elaborate than SED which reproduces a bit more QM results before getting interested.

But I think it is QM that is riducule every time such statements are made. And more importantly, the whole field of condensed matter is ridiculed, because they are completely ignored even when obvious QM observations are there. People seem to either ignore or be ignorant of the fact that the accepted standard values for fundamental constants such as "e" and "h" are obtained from condensed matter experiments. It is an insult to this field of study each time someone claims that classical mechanics can also emulate QM results. One can only claim that by pretending that the whole field of condensed matter does not exist.

Zz.

 

[vanesch]

It is incompatible with Bell's Theorem, and for many that is enough to exclude it a priori. And logically, given the SED program, it should be obvious that SED is doomed to fail if you accept Bell's Theorem - you don't need an experiment ("loophole-free" or not) at all to tell you this.

Well, SED proponents will say of course that Bell's theorem is only a proof that QM must be wrong in the end and that the day that we REALLY test QM versus the Bell theorem, that we'll be in for a surprise. Bell's theorem only shows that QM is fundamentally incompatible with what SED proponents want to construct, so we're at least sure that SED will NEVER be entirely equivalent to QM (in contrast to Bohmian mechanics, for instance). Their secret hope being that (Marshall: "the party will soon be over") an experiment will be performed one day, CONTRADICTING QM's predictions - their only fear being that scientists are soooo brainwashed that they will correct away that major discovery in order to save holy QM, but that sooner or later, this will give in. And then, they will show as the final vindicators of a century of misguided positivism (taratata...).
So my viewpoint is simply: if SED-like theories can suggest DOABLE experiments to challenge QM, that's always interesting. I wouldn't bet my money on QM failing, but experiment will have the last word. The day that it would turn out (to my great surprise) that QM is falsified, we'll talk again. In the mean time, we've had at least interesting experiments to do.

4. Why should any theory be given credit before it delivers? For that matter, why should any theory be given credit before it shows any promise? SED holds out absolutely NOTHING at the end of the rainbow. If it succeeds, we will have QM.

Nonono, they think that QM will be falsified. I couldn't think of any more exciting news in physics, honestly. So if all their thinking leads to experiments, I find that good, and if those experiments lead to a falsification of QM, also very good.
The only problem I have with many SED adepts is their almost religious devotion or better, horror for QM - but then, that's probably the only way you can get even INTERESTED in persuing such a path - that you can bet upon such a remote chance and spend a lot of energy on it. I couldn't for instance.

That story would be different IF it offered us something. For example, string theory at least promises a unification of GR and QFT as its premise - and that is clear and compelling!
So I guess it goes without saying that I personally am in the "SED has no promise" camp.

I think they view that differently, in that they are *right* (of course ) and that they are simply WAITING for the rest of the scientific community to be finally confronted with the evidence.

I realize that you want to be conciliatory to those with a differing viewpoints. (I hope my own cock-eyed ideas don't get reamed either. ) But there ARE good reasons why more efforts are not expended on research into alternative interpretations/explanations of QM's results. Careful strongly supports the SED program; you support the MWI program (and are a fine and reasonable advocate I might add!); ttn strongly supports the BM program. Each of you might feel there should be more research into a particular area because it shows promise.

There are fundamental differences between the 3 approaches. I think everybody recognizes that there is something called a "measurement problem" in QM ; two camps accept however, QM's phenomenal experimental success and don't think of fighting that, while the SED camp thinks that things were better before QM, and that experiment has not yet totally eliminated chances of going back.
BM sacrifices relativity (and has, to say the least, some difficulties with QFT), however, BM is in experimental agreement with QM.
BM is an instructive theory because it is *experimentally* correct (at least the non-relativistic version of it). This is something SED cannot claim: not all QM results have been reproduced yet (spectrum of neon, for instance ?). But what's difficult to accept with BM is that it shoots down relativity. On the other hand, there is NO interpretational problem with BM.
MWI is still something different. MWI is an interpretational scheme of QM. It sticks strictly to the formalism of QM, but tries to put back an ontological meaning to it - in other words, tries to make of QM something more than some kind of thermodynamics which has only epistemological meaning. There is not much need for research on MWI. The research on MWI is more on the different ways of formulating it so that it becomes more plausible (that we can postulate less and less, and derive more and more). I'm not complaining that there are not more departments involving in more research on MWI.

SED, BM and MWI all go in completely different directions! How can they all have equal promise?

Symmetry breaking
The unbroken symmetry: there are two idiots and one genius. That's something proponents of the 3 views agree upon.

 

[vanesch]

But I think it is QM that is riducule every time such statements are made. And more importantly, the whole field of condensed matter is ridiculed, because they are completely ignored even when obvious QM observations are there. People seem to either ignore or be ignorant of the fact that the accepted standard values for fundamental constants such as "e" and "h" are obtained from condensed matter experiments. It is an insult to this field of study each time someone claims that classical mechanics can also emulate QM results. One can only claim that by pretending that the whole field of condensed matter does not exist.
Zz.

Well, that's probably the difference between us I'm not emotionally involved (or at least, I try my very best not to). It is a dangerous attitude for a scientist to become emotionally involved with his convictions I'd say, because his very job is to be critical to them. It leads to suicide for people like Boltzmann. Now, nothing is more true for local realists of course: I think they are by far too much emotionally involved.

As I said: the day that QM is falsified would be GREAT NEWS. Not because I'm an ennemy of QM, but because it would be EXCITING. New stuff. So in a certain way, I'm pessimistic when I say that I wouldn't bet my money on it.

Being a particle physicist originally, I know what it means NOT to have something to falsify. Thirty god damned years nothing was discovered that was not expected. I really hope for a surprise when they turn on the LHC. If nothing special turns up, I think it will be about the end of experimental particle physics. So nobody is particularly emotionally involved with the standard model in particle physics.

 

[ZapperZ]

Well, that's probably the difference between us I'm not emotionally involved (or at least, I try my very best not to). It is a dangerous attitude for a scientist to become emotionally involved with his convictions I'd say, because his very job is to be critical to them. It leads to suicide for people like Boltzmann. Now, nothing is more true for local realists of course: I think they are by far too much emotionally involved.
As I said: the day that QM is falsified would be GREAT NEWS. Not because I'm an ennemy of QM, but because it would be EXCITING. New stuff. So in a certain way, I'm pessimistic when I say that I wouldn't bet my money on it.
Being a particle physicist originally, I know what it means NOT to have something to falsify. Thirty god damned years nothing was discovered that was not expected. I really hope for a surprise when they turn on the LHC. If nothing special turns up, I think it will be about the end of experimental particle physics. So nobody is particularly emotionally involved with the standard model in particle physics.

But you're comparing apples to donkeys. The Standard Model is phenomenological to begin with. It is RIPE for being modified.

And as for falsifying things, I don't need to repeat myself by telling you that I've been accused more than once after presenting my work that I'm "over-reaching" in terms of my work in systems that the Fermi Liquid model fails, and fails miserably. And experimentallist, I LIVE for the day that I discover something that totally violates some conventional, accepted physics theories. Nothing satisfies me more than to prove an theory wrong.

But this isn't the issue here. The issue is the often-neglected area of physics that is the foundation of MANY things in physics, not the least of which the source of many of the standard constants that we use. The challenges to QM have ALWAYS, without fail, neglect to address the HUGE body of phenomena form condensed matter. Why is that? People make a token attempt at the photoelectric effect with the classical picture, but they completely neglected that the "photoelectric effect" has graduate WAY beyond that. The photon picture works in describing (i) resonant photoemission (ii) angle-resolved photoemission (iii) x-ray photoemission (iv) multiphoton photoemission (which is completely ignored by those pushing classical theory), etc. I have seen zero classical descriptions for those.

I'm not emotionally attached to that field. If I were, I wouldn't have left it for accelerator physics. I am merely showing my annoyance that people make flippy remarks that "Oh, photoelectric effect can be explained classically", without ever considering that there MORE to that phenomenon that the primitive 1900's experiments done by Millikan. And the almost completely absence of any address regarding superconductivity is, to me, a HUGE glaring hole in any classical argument. Again, why is that? Why is the focus on extremely tough experiments on "local realism", then there's that 90000 lbs gorilla sitting right in front of you?

Zz.

 

[vanesch]

I am merely showing my annoyance that people make flippy remarks that "Oh, photoelectric effect can be explained classically", without ever considering that there MORE to that phenomenon that the primitive 1900's experiments done by Millikan. And the almost completely absence of any address regarding superconductivity is, to me, a HUGE glaring hole in any classical argument. Again, why is that? Why is the focus on extremely tough experiments on "local realism", then there's that 90000 lbs gorilla sitting right in front of you?

I agree with that of course, condensed matter physics (together with quantum chemistry) is the biggest producer of success stories for QM. However, these are complicated systems (especially if you want to think of the system as one hugely complicated kind of wavelet in CM) which are totally untractable for exact calculations, in QM as well as in CM, so I can somehow understand the remark that "well, our theory is probably going to be correct, but it will be too complicated to calculate anything for such a complex system. So it is not a priori excluded that IF WE WERE TO FIND a way to do that calculation - which we can't, sorry - that we would find the same result as you are having now with QM. Sheer luck, the two approximations (your real one, in QM, and my imaginary one in my future theory of which I'm already convinced that I won't find it) could come out the same, you never know".

So this is not a logical EXCLUSION of a classical theory. The gorilla, after all, might be a pile of ants which move exactly as a running gorilla, making the same noises too, and eating leaves exactly the way a gorilla does. It's not excluded. (just hit it with a stick to find out :-)

The next argument is of course that before those QM approximations were found, millions of man-years have been spend ; if only they would have been spend on the CM side, the results might have been similar - you never know.

It is the "you never know" that saves the CM side. I find that highly improbable too, but not totally excluded.

 

[ZapperZ]

I agree with that of course, condensed matter physics (together with quantum chemistry) is the biggest producer of success stories for QM. However, these are complicated systems (especially if you want to think of the system as one hugely complicated kind of wavelet in CM) which are totally untractable for exact calculations, in QM as well as in CM, so I can somehow understand the remark that "well, our theory is probably going to be correct, but it will be too complicated to calculate anything for such a complex system. So it is not a priori excluded that IF WE WERE TO FIND a way to do that calculation - which we can't, sorry - that we would find the same result as you are having now with QM. Sheer luck, the two approximations (your real one, in QM, and my imaginary one in my future theory of which I'm already convinced that I won't find it) could come out the same, you never know".

But this is where I disagree. It is an advantage, not a disadvantage, that such large system CAN exhibit QM phenomenon. It dismisses all those claims that QM effects can only be seen at the microscopic level. The fact that we CAN detect, test, measure, etc. superconductivity at the macroscopic level is the biggest reason for pointing out the gorilla. It isn't a glob of ants, because the glob of ants have to work in such a coherent fashion that has never been observed in nature. It requires that you make up behavior that isn't present in the ants that somehow knows how to behave has the legs, arms, head, rear end, etc. of the gorilla. This would be a speculation that has no basis, and that is what you end up having to make when you apply classical physics to such a system.

So this is not a logical EXCLUSION of a classical theory. The gorilla, after all, might be a pile of ants which move exactly as a running gorilla, making the same noises too, and eating leaves exactly the way a gorilla does. It's not excluded. (just hit it with a stick to find out :-)
The next argument is of course that before those QM approximations were found, millions of man-years have been spend ; if only they would have been spend on the CM side, the results might have been similar - you never know.
It is the "you never know" that saves the CM side. I find that highly improbable too, but not totally excluded.

But you might as well argue that there's no logical exclusion of the Caloric theory and all the other extinct theories of science. To what extent do you stop? Again, I go back to the mantra that has been asked of me: It may be interesting, but is it important? Where do you stop and say that enough is enough - I no longer have the resources to devote to that, and it tells me nothing of importance.

Again, my measuring stick is very simple. Until I see classical mechanics provides an accurate description of superconductivity, it will remain a theory incapable of approaching QM. This is not discarding anything. It is simply the LOGICAL choice of the two based on what it can ALREADY do.

Zz.

 

[DrChinese]

Symmetry breaking

The unbroken symmetry: there are two idiots and one genius. That's something proponents of the 3 views agree upon.

That's funny!

BTW: I like excitement, too. But "predictable" physics will not be the end of experimental efforts... rather it is the lifeblood of research. Lab effort makes more sense if the expected pay-off involves lower risk. That may be boring, but it is hard to argue with. As I am a utilitarian when it comes to theory, I value such pay-offs highly.

 

[NateTG]

It seems like there are a variety of motivations that drive people to try to make 'classical' versions of quantum mechanics.
Computational tractability: Classical mechanics are, after all, computationally much simpler. Quantum Mechanics models with 'nice' computational characteristics have very legitemate untility value.
Metaphysical motivations: Quantum aspects of things are conceptually difficult. A 'classical' model of QM could make QM conceptrually more tractable which could provide a similar sort of utility value to the computational simplification since it would make it easier for people to indentify assumptions, or interesting new questions.
Compatability with other theories: This is the infamous nut of unifying Relativity and Quantum Mechanics, and, more or less, spans the two motivations above since an important aspect of unifying these theories is unifying the concepts and mathematics of the merging theories.

 

[RandallB]

challenges to QM have ALWAYS, without fail, neglect … condensed matter …. works in describing ………( ignored by those pushing classical), ….
I have seen zero classical descriptions for those.

I don’t get it. Are you saying you have seen someone give reasonable classical descriptions for simpler phenomena like double slit or entanglement? But before considering them you need them to address condensed matter as well? (I haven’t, so do tell)

How are any of the basic “paradoxes” that are only resolved by QM ideas any less of a gorilla to solve than condensed matter is to CM?

Any legit classical solution to anyone of the QM basics would be just as significant a start.
CM just has to recognize that on this final segment of the race to understand nature it just has not found a proper starting gate yet. From that perspective the question is can anyone prove there is no gate to find for CM, and I don’t think that’s been done yet either.

 

[ZapperZ]

I don’t get it. Are you saying you have seen someone give reasonable classical descriptions for simpler phenomena like double slit or entanglement? But before considering them you need them to address condensed matter as well? (I haven’t, so do tell)

I never said those were "simpler". You CAN describe the double slit using classical optics, but only if you use wave phenomenon as a starting point and not "very low intensity" limit of the light source. When you start using that, then the double slit detection from the classical wave point of view starts to get muddled.

And I certainly don't consider the entanglement phenomenon as "simpler".

Here's the deal. The MORE you have to produce "single" of any object to detect QM phenomenon, the more difficult it is. This is the main reason why most people think QM effects are only "microscopic". Superconductivity and superfludity are QM phenomena at the MACROSCOPIC level. It involves a gazillion particles at once. You can make DIRECT measurements and observations. That is what's so astounding about these things.

How are any of the basic “paradoxes” that are only resolved by QM ideas any less of a gorilla to solve than condensed matter is to CM?
Any legit classical solution to anyone of the QM basics would be just as significant a start.
CM just has to recognize that on this final segment of the race to understand nature it just has not found a proper starting gate yet. From that perspective the question is can anyone prove there is no gate to find for CM, and I don’t think that’s been done yet either.

Eh?

Zz.

 

[Sherlock]

I have noticed several of these discussions going on in a number of threads, i.e. the apparent "validity" of classical description, and the idea that you cannot observe directly the manifestation of quantum phenomena. At the risk of exposing my utmost annoyance of such claims, I will try to point out a very obvious 90000-pound gorilla that almost everyone seems to have ignored - SUPERCONDUCTIVITY.

I didn't know anything about superconductivity until I read this post (and then was motivated to read up a bit on it). Thanks for the link to Mead's paper, which I've read and will reread.
Anyway, I was just asking a question in my post. I don't know quantum theory well enough to think that it should (or if it can) be changed, and I don't know the details of all the various experimental quantum phenomena well enough to have any good idea whether or not there's any reason to think that they might all be explained classically or semi-classically or whatever (although I've read some papers on this in the course of plodding through my quantum theory text).
Now, at the risk of sounding super ignorant, what is it that makes the superconductivity phenomenon a uniquely quantum phenomenon with, as you seem to indicate, no hope of ever being described in a classically visualizable way?