Wave-particle duality at Macro scale?

  • Thread starter bohm2
  • Start date
  • #1
825
53

Main Question or Discussion Point

No-one is suggesting that this is exactly the same as the wave-particle duality that exists at the quantum scale (e.g. non-locality) but I thought these papers looking at the behaviour of “walking droplets” that can be seen at the macroscale were very interesting:

By virtue of its wave particle nature, the walking drop exhibits several features previously thought to be peculiar to the microscopic realm, including single-particle diffraction, interference, tunneling, and now, quantized orbits. These studies raise a number of fascinating questions. Are the macroscopic and microscopic worlds really so different? Might the former yet yield insight into the latter? Is there really a connection between this bouncing droplet system and the microscopic world of subatomic particles? Or is it all just an odd coincidence? By virtue of its accompanying pilot wave, the walker’s dynamics are temporally nonlocal, depending on its bouncing history, its memory.
Quantum mechanics writ large
http://www-math.mit.edu/~bush/PNAS-2010-Bush.pdf

Walking Droplets-A form of Wave-particle duality at macroscopic scale?
http://www.df.uba.ar/users/dasso/fis4_2do_cuat_2010/walker.pdf

Path-memory induced quantization of classical orbits
http://www.pnas.org/content/107/41/17515.full.pdf

Full thesis:
http://bictel.ulg.ac.be/ETD-db/collection/available/ULgetd-09262011-010800/unrestricted/2011_Terwagne_these.pdf
 

Answers and Replies

  • #2
No-one is suggesting that this is exactly the same as the wave-particle duality that exists at the quantum scale (e.g. non-locality) but I thought these papers looking at the behaviour of “walking droplets” that can be seen at the macroscale were very interesting:



Quantum mechanics writ large
http://www-math.mit.edu/~bush/PNAS-2010-Bush.pdf

Walking Droplets-A form of Wave-particle duality at macroscopic scale?
http://www.df.uba.ar/users/dasso/fis4_2do_cuat_2010/walker.pdf

Path-memory induced quantization of classical orbits
http://www.pnas.org/content/107/41/17515.full.pdf

Full thesis:
http://bictel.ulg.ac.be/ETD-db/collection/available/ULgetd-09262011-010800/unrestricted/2011_Terwagne_these.pdf

My! That's got to be one of the cleverest experimental setups ever.
 
  • #3
1,466
372
Certainly no surprises.

Yves Couder emailed me back this:

Hi,

Your question is excellent. We call a walker the ensemble of the droplet and its associated wave. Since the work you refer to we have shown that the wave field contains a memory of the past trajectory that is at the origin of the quantum like effects we observe. You will find attached a recent work dealing with this effect.
In the double slit experiment, while the droplet passes through one slit the associated wave passes through both so that one coud say that the walker passes through both.
Our system is similar to a pilot wave system and this is what we are working on recently. These models are usually called de Broglie - Bohm models, a term that is very misleading because the two approaches are different from one another.
Bohm gets a dynamical equation from Shrödinger equation so that it concerns the dynamics of a maximum of probability. What de Broglie had in mind was a the dynamics of an individual particle associated with a wave.
Our system appears to be closer to de Broglie.

Best regards

Yves Couder
 
  • #4
825
53
Bohm gets a dynamical equation from Shrödinger equation so that it concerns the dynamics of a maximum of probability. What de Broglie had in mind was a the dynamics of an individual particle associated with a wave. Our system appears to be closer to de Broglie.
I think Antony Valentini is very much supportive of de Broglie's approach vs Bohm's, from my understanding and is particularly critical of imposing a Lorenz-invariant extension into the pilot wave. I'm not sure what Valentini thinks of H. Nikolic's relativistic covariant version of Bohmian mechanics? There does seem to be a divergence of opinion between him and the Goldstein/Durr/Tumulka et al. team also with respect to the ontology of the wave function/pilot wave. The latter treating it as nomological while Valentini prefering a new type of non-local "causal" agent. Regardless, this stuff is very interesting for people who favour the "realist" interpretation. An interesting passage from Valentini is the following:

It has taken some 80 years for de Broglie's theory to be rediscovered, extended and fully understood. Today we realize that de Broglie's original theory contains within it a new and much wider physics, of which ordinary quantum theory is merely a special case-a radically new physics that might perhaps be within our grasp.

In the author’s view, the pilot wave should be interpreted as a new causal agent, more abstract than forces or ordinary fields. This causal agent is grounded in configuration space – which is not surprising in a fundamentally ‘holistic’, nonlocal theory.

Durr et al. have proposed what is, in effect, a mixture of first-order (Aristotelian) dynamics with second-order (Galilean) kinematics. We assert on the basis of the above reasoning that such a mixture is physically incongruous. An Aristotelian dynamics requires an Aristotelian kinematics.

Thus Holland is consistent when he asserts that Galilean invariance is a fundamental symmetry, for he bases the dynamics on the quantum potential. But then things become rather inelegant, and also difficult. The quantum potential itself is inelegant. The Galilean transformation of the wavefunction is mathematically peculiar, having no simple geometrical interpretation. And a Galilean-invariant theory invites attempts at a Lorentz-invariant extension, leading to enormous complications.
Beyond the Quantum
http://arxiv.org/PS_cache/arxiv/pdf/1001/1001.2758v1.pdf

On Galilean and Lorentz invariance in pilot-wave dynamics
http://arxiv.org/PS_cache/arxiv/pdf/0812/0812.4941v1.pdf
 
Last edited:
  • #5
It's good to see thoughts are evolving since we first discussed this experiment on Physics Forums. I would be interested in having any information on recent Heinz von Foerster congress on Emergent Quantum Mechanics where Yves Couder held the http://www.univie.ac.at/hvf11/congress/EmerQuM.html".
 
Last edited by a moderator:
  • #6
736
34
It's good to see thoughts are evolving since we first discussed this experiment on Physics Forums. I would be interested in having any information on recent Heinz von Foerster congress on Emergent Quantum Mechanics where Yves Couder held the opening lecture.
Actually, I was at that conference. What specifically are you interested in?
 
  • #7
825
53
Another interesting paper on this topic. Can someone summarize what the hi-lited parts are implying?

From Abstract:
It is shown that each shock emits a radial travelling wave, leaving behind a localized mode of slowly decaying Faraday standing waves. As it moves, the walker keeps generating waves and the global structure of the wave field results from the linear superposition of the waves generated along the recent trajectory. For rectilinear trajectories, this results in a Fresnel interference pattern of the global wave field. Since the droplet moves due to its interaction with the distorted interface, this means that it is guided by a pilot wave that contains a path memory. Through this wave-mediated memory, the past as well as the environment determines the walker's present motion.
From the body/discussion part of the paper:
Early in the history of quantum mechanics, de Broglie suggested that elementary particles could be guided by their association with a pilot wave (de Broglie 1926). In an attempt to restore determinism in quantum mechanics, this idea was revisited by Bohm (1952). Our system, in which a particle (the droplet) is guided by its associated wave, appears as the first experimental implementation of the idea of a pilot wave and it does lead to quantum-like behaviours. However, in our system, while the association of the particle with the wave is a necessary condition to obtain those behaviours, it is not sufficient. Their observation also requires that the waves contain information on the droplet’s past trajectory, what was called (Fort et al. 2010) the wave-mediated path memory of the system.
When the walker is forced into a circular motion by an applied transverse force, only certain trajectories are possible, generating a wave field with a fixed structure that rotates with the droplet. This leads to a quantization of the possible orbits as shown in Fort et al. (2010). Other dramatic effects of the memory are observed whenever boundaries generate any kind of confinement of the walker. In these situations, the waves emitted in the past and reflected by the boundaries lead to a complex structure of the interference field and correspondingly to a disorder in the droplet motion (Couder & Fort 2006). The present quantitative analysis will be an essential tool for a further investigation of those situations where a forced spatial localization generates an uncertainty in the walker velocity. Finally, the possible relevance of this type of temporal non-locality to particle physics appears an interesting open problem.

Information stored in Faraday waves: the origin of a path memory
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8266690

http://www.lpm.u-nancy.fr/webperso/chatelain.c/GrpPhysStat/PDF/WorshopNancy_EFort.pdf [Broken] (very cool slide presentation!)
 
Last edited by a moderator:
  • #8
825
53
This is a real cool video show this quantum-like macroscopic behaviour through the double-slit

Yves Couder . Explains Wave/Particle Duality via Silicon Droplets [Through the Wormhole]

https://www.youtube.com/watch?v=W9yWv5dqSKk
 
Last edited:
  • #9
825
53
Another paper on this topic that came out:
Macroscopic walkers were shown experimentally to exhibit particle and wave properties simultaneously. This paper exposes a new family of objects that can display both particle and wave features all together while strictly obeying laws of the Newtonian mechanics. In contrast to walkers, no constant inflow of energy is required for their existence. These objects behave deterministically provided that all their degrees of freedom are known to an observer. If, however, some degrees of freedom are unknown, observer can describe such objects only probabilistically and they manifest weird features similar to that of quantum particles. We show that such quantum phenomena as particle interference, tunneling, above-barrier reflection, trapping on top of a barrier, spontaneous emission of radiation have their counterparts in classical mechanics. In the light of these findings, we hypothesize that quantum mechanics may emerge as approximation from a more profound theory on a deeper level...One can speculate that a concept of wave function may emerge as a mathematical tool to cope with lack of information about all degrees of freedom of a soft body, and the Schrodinger equation may even be deduced from the first principles. Such program is in line with the vision of A. Einstein who predicted: ”Assuming the success of efforts to accomplish a complete physical description, the statistical quantum theory would, within the framework of future physics, take an approximately analogous position to the statistical mechanics within the framework of classical mechanics. I am rather firmly convinced that the development of theoretical physics will be of this type, but the path will be lengthy and difficult.”. The present paper advocates making first steps along this path.
Wave-particle duality in classical mechanics
http://lanl.arxiv.org/pdf/1201.4509.pdf

What I just don't understand is the conflicting opinions on this topic. I thought that the PBR (Pusey-Barrett-Rudolph) theorem that was discussed ad nauseum on this forum ruled out such a possibility (see links below)? I'm lost.

Papers:
The quantum state cannot be interpreted statistically (this is the original paper)
http://lanl.arxiv.org/abs/1111.3328
Generalisations of the recent Pusey-Barrett-Rudolph theorem for statistical models of quantum phenomena
http://xxx.lanl.gov/abs/1111.6304
Completeness of quantum theory implies that wave functions are physical properties
http://arxiv.org/PS_cache/arxiv/pdf/1111/1111.6597v1.pdf

Popular:
Quantum theorem shakes foundations
http://www.nature.com/news/quantum-theorem-shakes-foundations-1.9392

Blogs:
http://mattleifer.info/2011/11/20/can-the-quantum-state-be-interpreted-statistically/ (best article)
http://www.scottaaronson.com/blog/?p=822
http://www.fqxi.org/community/forum/topic/999
 
  • #10
825
53
A very interesting lecture presentation (~ 83 minutes) from Perimeter by Yves Couder:
It is usually assumed that the quantum wave-particle duality can have no counterpart in classical physics. We were driven into revisiting this question when we found that a droplet bouncing on a vibrated bath could couple to the surface wave it excites. It thus becomes a self-propelled "walker", a symbiotic object formed by the droplet and its associated wave. Through several experiments, we addressed one central question. How can a continuous and spatially extended wave have a common dynamics with a localized and discrete droplet? Surprisingly, quantum-like behaviors emerge; both a form of uncertainty and a form of quantization are observed. This is interesting because the probabilistic aspects of quantum mechanics are often said to be intrinsic and to have no possible relation with underlying unresolved dynamical phenomena. In our experiment we find probabilistic behaviors and they do have a relation with chaotic individual trajectories. These quantum like properties are related in our system to the non-locality of a walker that we called its "wave mediated path memory". The relation of this experiment with the pilot wave model proposed for quantum mechanics by de Broglie will be discussed.
A Macroscopic-scale Wave-particle Duality : the Role of a Wave Mediated Path Memory
http://pirsa.org/displayFlash.php?id=11100119
 
  • #11
463
7
What I just don't understand is the conflicting on this . I thought that the PBR (Pusey-Barrett-Rudolph) theorem that was discussed ad nauseum on this forum ruled out such a possibility (see links below)? I'm lost.
not yet (and maybe never)...

arguing for ψ-epistemic
Epistemic view of quantum states and communication complexity of quantum channels
Alberto Montina
http://arxiv.org/pdf/1206.2961.pdf

...We show that classical simulations employing a finite amount of communication can be derived from a special class of hidden variable theories where quantum states represent statistical knowledge about the classical state and not an element of reality...
...In this paper, we will show that ψ-epistemic theories have a pivotal role also in quantum communication and can determine an upper bound for the communication complexity of a quantum channel...


Reconstruction of Gaussian quantum mechanics from Liouville mechanics with an
epistemic restriction

Stephen D. Bartlett, Terry Rudolph, Robert W. Spekkens
http://arxiv.org/pdf/1111.5057.pdf

...The success of this model in reproducing aspects of quantum theory provides additional evidence in favour of interpretations of quantum theory where quantum states describe states of incomplete knowledge rather than states of reality...


----
arguing for ψ-ontic

Maximally epistemic interpretations of the quantum state and contextuality
M. S. Leifer, O. J. E. Maroney
http://arxiv.org/pdf/1208.5132.pdf

...This implies that the Kochen-Specker theorem is sufficient to establish both the impossibility of maximally epistemic models and the impossibility of preparation noncontextual models...
..........but
...If one could prove, without auxiliary assumptions, that the support of every distribution in an ontological model must contain a set of states that are not shared by the distribution corresponding to any other quantum state, then these results would follow. Whether this can be proved is an important open question...
 
Last edited:
  • #12
463
7
buyers beware....


R. Spekkens

http://arxiv.org/pdf/1209.0023v1.pdf
...Such a principle does not force us to operationalism, the view that one should only seek to make claims about the outcomes of experiments...

but he contradicts itself !

http://www.perimeterinstitute.ca/en/Events/Quantum_Foundations_Summer_School/QFSS_Abstracts/ [Broken]
...it is useful to characterize the theory entirely in terms of the observable consequences of experimental procedures, that is to say, operationally...
 
Last edited by a moderator:
  • #13
868
3
buyers beware....


R. Spekkens

http://arxiv.org/pdf/1209.0023v1.pdf
...Such a principle does not force us to operationalism, the view that one should only seek to make claims about the outcomes of experiments...

but he contradicts itself !

http://www.perimeterinstitute.ca/en/Events/Quantum_Foundations_Summer_School/QFSS_Abstracts/ [Broken]
...it is useful to characterize the theory entirely in terms of the observable consequences of experimental procedures, that is to say, operationally...
Perhaps pointing out the contradiction would be helpful. I don't see it?
 
Last edited by a moderator:
  • #14
868
3
The best I can figure you are drawing a dichotomy between operationalism verses (general) realism. That is to say that you are implying that Spekkens contradicted himseld by on the one hand saying operational descriptions where "useful", while on the other saying we are not forced into operationalism. Only the "law of excluded middle" does not apply here, i.e., the implied dichotomy is false.

Sighting a target through the provided sights of a gun is operationally "useful", but you are by no means required to do so. To provide an operational characterization is indeed useful, regardless of how limited such an operational description is in a given theoretical construct. Just consider what immediately followed what you quoted of Spekkens.

Such a principle does not force us to operationalism, the view that one should only seek to make claims about the outcomes of experiments. For instance, if one didn’t already know that the choice of gauge in classical electrodynamics made no difference to its empirical predictions, then discovery of this fact would, by the lights of the principle, lead one to renounce real status for the vector potential in favour of only the electric and magnetic field strengths. It would not, however, justify a blanket rejection of any form of microscopic reality
 
  • #15
463
7
Perhaps pointing out the contradiction would be helpful. I don't see it?

not a dichotomy, is abrogate a method and later downplay it.
nothing to do with X versus Y...... `realism vs operationalism´ stuff
 
  • #16
868
3
not a dichotomy, is abrogate a method and later downplay it.
nothing to do with X, versus Y...... "realism vs operationalism"
I figured I was off in my characterization of your contradiction. Which is why I asked before making a guess. However, you didn't explain what contradiction you intended with this response?

First off Spekkens never abrogated operationalism, nor its negation. To say some principle does not "force" us into operationalism is not an abrogation of operationalism. Operationalism fully retains its "usefulness" irrespective of whether we entirely restrict ourselves to it or not. neither does admitting the "usefulness" of operationalism downplay the claim that theoretical constructs are not required to be strictly operational descriptions.

I guess what I really need is a better explanation of exactly how you think he may have contradicted himself?
 
  • #17
463
7
To say some principle does not "force" us into operationalism is not an abrogation of operationalism.

who said that ?



.
 
  • #18
868
3
To say some principle does not "force" us into operationalism is not an abrogation of operationalism.
who said that ?

.
I'll answer the above question, but why haven't you answered my question? The same question started with and repeated.

Answer:
Spekkens, from your quote, said: "...Such a principle does not force us into operationalism,... To which you responded to me pointing out the use of the term "force" with: "is abrogate a method and later downplay it".

Question:
So answer the original question... What was the contradiction you thinks Spekkens was guilty of? With the above question you posed I don't even know what you claimed was abrogated or downplayed.
 
  • #19
463
7
I figured I was off in my characterization of your contradiction. Which is why I asked before making a guess. However, you didn't explain what contradiction you intended with this response?

First off Spekkens never abrogated operationalism, nor its negation. To say some principle does not "forces" us into operationalism is not an abrogation of operationalism. Operationalism fully retains its "usefulness" irrespective of whether we entirely restrict ourselves to it or not. neither does admitting the "usefulness" of operationalism downplay the claim that theoretical constructs are not required to be strictly operational descriptions.

I guess what I really need is a better explanation of exactly how you think he may have contradicted himself?
you did, not me......
 
Last edited:
  • #20
868
3
Apparently you don't want to answer the question. Nor does the above quote make any sense.
 
  • #21
463
7
Nor does the above quote make any sense.
A lot of sense, you attribute to me, things I have not done, but you do not become aware...
see below

Spekkens, from your quote, said: "...Such a principle does not us into operationalism,... To which you responded to me pointing out the use of the term "force" with: "is abrogate a method and later downplay it".
i answered, what ?!
the term FORCE with quotations marks ? :surprised
where !!! i answered that ?
pointing out ?!!! what ?!
no way, re-read the posts and you will see....


read your post 17 and you will see your mistake.
 
Last edited:
  • #22
868
3
A lot of sense, you attribute to me, things I have not done, but you do not become aware...
see below
Yeah, I accepted that. But I asked for clarification which you never provided.



i answered, what ?!
The problem is you never did answer.


the term FORCE with quotations marks ? :surprised
I put the word "force" in quotations before it was a quote of Spekkens, not you. I even requoted Spekkens and put the word "force" in red so you would know what it referred to.


where !!! i answered that ?
pointing out ?!!! what ?!
no way, re-read the posts and you will see....
How can I see when you still haven't answered my question.

read your post 17 and you will see your mistake.
Post #17 was the one where I admitted my characterization was probably wrong.
I figured I was off in my characterization of your contradiction. Which is why I asked before making a guess. However, you didn't explain what contradiction you intended with this response?
Yet you still have not answered.

Answer this one question:
What contradiction was you referring to in post #13?
Repeat:
What contradiction was you referring to in post #13?
Repeat:
What contradiction was you referring to in post #13?
 
  • #23
101
2
Love these links you throw at us, Bohm2 :-)

But: I'm trying to understand this in a intuitive way as I lack the mathematical insight.

I have two questions regarding the link form an earlier post by Bohm2, november 2011:

Beyond the Quantum by Valentini:
http://arxiv.org/PS_cache/arxiv/pdf/...001.2758v1.pdf [Broken]

On top of page 6, Valentini writes about the fate of The Pilot Wave Theory on the 1927 Solway conference: "de Broglie seems not to have recognized that his dynamics was irreducibly non-
local. Nor was this recognized by anyone else at the conference. The action of
the wave in multidimensional configuration space is such that a local operation
on one particle can have an instantaneous effect on the motions of other (distant)
particles."

Why is the Pilot Wave Theory irreducibly non-local - which aspect of the theory predicts that entangled particles react to each other instantly, disregarding relativity? Can someone please try to explain that to me... in plain english if possible? (It's a classical description of quantum mechanics, so we can start visualising things again, right?)

AND from that same link page 7, line 4:

"Bell made it clear that the pilot wave is a ‘real objective field’ in configuration
space, and not merely a mathematical object or probability wave."

I'm having trouble understanding/picturing what is meant by "configuration space" and a "wave in multidimensional configuration space". Would it be approximately right to think of this wave in configuration space as the wave of each particle existing in it's own space-time interacting with all other particles waves in their space-times... or more dramatic: "The particle's universal wave up against the United Universal Waves of The Universe" ("United Space" for short :-)?

Hope someone can help me to understand this better - I find it very interesting.

Best, Henrik
 
Last edited by a moderator:
  • #24
825
53
I'm having trouble understanding/picturing what is meant by "configuration space" and a "wave in multidimensional configuration space".
Not sure if this is what you are looking for or if you've already read the links in that thread but I started a thread on the topic wth many intoductory links on the topic. You might find the papers in that thread very interesting and they're pretty descriptive/more philosophical:

The reality of configuration space
https://www.physicsforums.com/showthread.php?t=554543
 
  • #25
106
10
Just to echo Hernik, thanks for your efforts here, bohm. Once again I've got plenty of new homework waiting for me!
 

Related Threads on Wave-particle duality at Macro scale?

Replies
2
Views
2K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
2
Views
1K
  • Last Post
2
Replies
43
Views
8K
  • Last Post
Replies
1
Views
856
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
7
Views
3K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
3
Views
2K
Top