Wave-particle duality at Macro scale?

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.

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/fis...010/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/colle...agne_these.pdf

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

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.

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.

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.

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.

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.

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.

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.

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.

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/...FSS_Abstracts/
...it is useful to characterize the theory entirely in terms of the observable consequences of experimental procedures, that is to say, operationally...

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

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"

To say some principle does not "force" us into operationalism is not an abrogation of operationalism.