Wave-particle duality at Macro scale?

[jarekd]

For this to happen, a wave must occupy a very high number of dimensions so particles can affect one another over large distances, faster than the speed of light. However, in a walker system the waves will always occupy just two dimensions, given by the length and width of the oil tank.

From one side, wave theories in e.g. two dimensions have already infinite number of degrees of freedom - how many more do they need?
From the other, I haven't seen any experiment with "faster than the speed of light" communication(?) ... sure quantum physicists love plane waves - which are spread over the whole Universe, but it doesn't mean they really are - as we know, propagation of information cannot exceed the speed of light.

 

[bohm2]

From one side, wave theories in e.g. two dimensions have already infinite number of degrees of freedom - how many more do they need?
From the other, I haven't seen any experiment with "faster than the speed of light" communication(?) ... sure quantum physicists love plane waves - which are spread over the whole Universe, but it doesn't mean they really are - as we know, propagation of information cannot exceed the speed of light.

I didn't take them as necessarily implying FTL communication. What I don't understand about Maudlin's response is that some researchers like the links above and Grossing have developed models based on Couder stuff for non-locality/entanglement:

A Classical Framework for Nonlocality and Entanglement
http://arxiv.org/pdf/1210.4406.pdf

"Systemic Nonlocality" from Changing Constraints on Sub-Quantum Kinematics
http://arxiv.org/pdf/1303.2867v1.pdf

So, as I see it, I'm not sure Maudlin's point is completely accurate?

 

[kye]

How is bohm pilot wave theory understood in the context of gauge theory? are pilot waves local symmetry gauge or global symmetry gauge entities or are they outside of gauge theory and no connection?

 

[cody1980]

I am certainly a layman, so I ask here in humility and in hopes of improving my understanding. Has anyone tried to perform a similar experiment to Couder's oil droplets but in a three-dimensional setup? I am thinking perhaps that you could have a tank full of fluid and, I dunno, maybe mechanical balls that vibrated at a certain frequency. Would they generate wave fields that would propel them around the tank? Would multiple balls exhibit these same "quantum" effects but in three dimensions? I'm sure the wave patterns could be more complex in three dimensions and might yield more quantum similarities. One advantage of having balls that vibrate instead of causing the medium to vibrate would be that you could have particles of multiple frequencies interacting with one another at the same time. Then again, gravity might throw the experiment off, so ideally it would be done in 0 G, I guess.

 

[bohm2]

Interesting hi-lites from the November 2013 issue of Physics World discussing these experiments:

Indeed, Physics World contacted a number of physicists and philosophers with a background in quantum foundations, and found that most were sceptical that the walker systems could shed light on the mysteries of the quantum world. “The reproduction of two-slit interference is impressive,” says philosopher Peter Lewis from the University of Miami in Florida, US, “but I think the disanalogies between the [walker] system and the pilot-wave theory are just as important as the analogies, and perhaps more so.”...

Most were sceptical – but not all. One exception was theoretical physicist Antony Valentini at Clemson University in South Carolina, US, who points out that walker systems are not the first to present strong analogues of a hard-to-grasp theory: the last decade has seen numerous experimental attempts to produce analogues of gravity, using fluids and light. “People are now wondering if we should look at these [analogue gravity] models and use them for inspiration when we’re looking at how our current theories of gravity might break down at short distances,” he says...

There is already good reason to think that the walkers might exhibit some sort of pseudo nonlocality. Fort and Couder find that the dynamics of walkers is governed largely by the “memory” of past waves, which gradually builds up over the oil bath into a wave field. In this way, the Paris researchers say, one walker can seem to nonlocally affect another walker on the other side of the bath, thanks to a wave – or combination of waves – it emitted previously. This “memory” effect was key to the observed quantization of walker orbits on a rotating oil bath. This year, the researchers demonstrated the memory effect in a more general sense: if a walker is left long enough, its trajectory becomes “entangled” with a wave field in the bath.

Classically quantum
http://physicsworld.com/cws/article/indepth/2013/nov/07/classically-quantum

 

[huelsnitz]

hydraulic quantum analogs

I actually wrote a blog article about this a couple weeks ago:

http://www.thefunisreal.com/2013/10/hydrodynamic-quantum-analogs/

My feeling is that the droplet experiments and quantum systems share similar dynamics. Sort of like a mass on a spring can be explained by the same equations used to describe an RLC circuit. It does not mean the two systems are identical, just that there are dynamical similarities.

So, the message I get from these hydraulic quantum analog experiments is that they can help us understand quantum systems better (particularly after they get more sophisticated). Also, they lend hope to the realist interpretations of QM that seek a conceptual understanding of what is going on, rather than a "shut up and calculate" mentality.

The MIT group is working on being able to demonstrate entanglement with a droplet experiment.

This is cool stuff! I love watching the droplet videos again and again.

 

[bohm2]

The MIT group is working on being able to demonstrate entanglement with a droplet experiment.

You might find this paper on classical entanglement as an effect of contextuality interesting:

We show that for two classical brownian particles there exists an analog of continuous-variable quantum entanglement: The common probability distribution of the two coordinates and the corresponding coarse-grained velocities cannot be prepared via mixing of any factorized distributions referring to the two particles in separate. This is possible for particles which interacted in the past, but do not interact in the present. Three factors are crucial for the effect: 1) separation of timescales of coordinate and momentum which motivates the definition of coarse-grained velocities; 2) the resulting uncertainty relations between the coordinate of the brownian particle and the change of its coarse-grained velocity; 3) the fact that the coarse-grained velocity, though pertaining to a single brownian particle, is defined on a common context of two particles. The brownian entanglement is a consequence of a coarse-grained description and disappears for a finer resolution of the Brownian motion. We discuss possibilities of its experimental realizations in examples of macroscopic brownian motion.

Brownian Entanglement.
http://arxiv.org/pdf/quant-ph/0412132v1.pdf

 

[billschnieder]

Another "double-slit" experiment using molecules, explained classically, vindicating Einsteins view.
http://prl.aps.org/abstract/PRL/v111/i10/e103201

They use the momentum-transfer-from-discrete-particles description pioneered by William Duane, rather than the wave-particle duality to explain it.

Phys. Rev. Lett. 111, 103201
Momentum Transfer to a Free Floating Double Slit: Realization of a Thought Experiment from the Einstein-Bohr Debates

We simultaneously measured the momentum transferred to a free-floating molecular double slit and the momentum change of the atom scattering from it. Our experimental results are compared to quantum mechanical and semiclassical models. The results reveal that a classical description of the slits, which was used by Einstein in his debate with Bohr, provides a surprisingly good description of the experimental results, even for a microscopic system, if momentum transfer is not ascribed to a specific pathway but shared coherently and simultaneously between both.

 

[TrickyDicky]

Someone mentioned the possibility of going from 2D to 3D fluid experiments.
Do these experiments point towards the possibility of gaining insights about QM from continuum or fluid models(as opposed to many-body models)?

 

[kye]

I actually wrote a blog article about this a couple weeks ago:

http://www.thefunisreal.com/2013/10/hydrodynamic-quantum-analogs/

My feeling is that the droplet experiments and quantum systems share similar dynamics. Sort of like a mass on a spring can be explained by the same equations used to describe an RLC circuit. It does not mean the two systems are identical, just that there are dynamical similarities.

So, the message I get from these hydraulic quantum analog experiments is that they can help us understand quantum systems better (particularly after they get more sophisticated). Also, they lend hope to the realist interpretations of QM that seek a conceptual understanding of what is going on, rather than a "shut up and calculate" mentality.

The MIT group is working on being able to demonstrate entanglement with a droplet experiment.

This is cool stuff! I love watching the droplet videos again and again.

Can the double slit illustration in the droplet videos produced intereference patterns? It's not shown in the Morgan Freeman's documentary. The particle doesn't go straight because there is other waveforms that pass thru the other slit but can they produced the same interference patterns as the quantum double slit experiment?

 

[bohm2]

Can the double slit illustration in the droplet videos produced intereference patterns?

Yes as posted in a number of posts above:

The wave emitted by the droplet "interfered with its own reflections," and that the droplet's normally straight trajectory deviated when passing through the slit. The remarkable feature was that even with identical initial conditions, the deviation of a given individual walker appeared random, while the deviation of many walkers revealed an interference pattern.

http://phys.org/news78650511.html

Single-particle diffraction and interference at a macroscopic scale
http://users.isy.liu.se/en/jalar/kurser/QF/assignments/Couder2006.pdf

 

[kye]

Yes as posted in a number of posts above:


http://phys.org/news78650511.html

Single-particle diffraction and interference at a macroscopic scale
http://users.isy.liu.se/en/jalar/kurser/QF/assignments/Couder2006.pdf

Why was this missed for a hundred years ago since the lecture by De Broglie about the pilot waves. What's the community reactions to this and what problems they still have to solve or surmount. What's the QFT version of it? I think I read in sciam about black hole being described by fluid dynamics. So does this mean the vacuum is fluid or something like this? What is the ramifications.

 

[bohm2]

Why was this missed for a hundred years ago since the lecture by De Broglie about the pilot waves. What's the community reactions to this and what problems they still have to solve or surmount. What's the QFT version of it? I think I read in sciam about black hole being described by fluid dynamics. So does this mean the vacuum is fluid or something like this? What is the ramifications.

See post # 42. I think it should answer most of your questions.

 

[bohm2]

I thought this was an interesting relationship between Khrennikov's classical model and Couder experiments. Khrennikov evades non-locality by relying on a non-Kolmogorov probability contextual probabilistic model. With respect to correlations seen between trials in the two-slit experiment he argues that:

Trials in the two slit experiment are not independent. We have to test our prediction in physical experiments. At the moment, we do not know where the information about previous trails is accumulated? There are three (less or more natural) possibilities:

(1) It is accumulated in the aperture. A new particle does not go through the aperture independently with previous particles.

(2) Previous particles change a structure of the screen. The position of a new particle on the screen depends on these previous changes.

(3) The source of particles accumulates an information about previous particles.

It seems to be that (1) and (3) are the most important possibilities. What kind of experiments may test these hypothesis? To exclude the correlations in the source of particle, we need a source of single particles which could not accumulate the information on previous particles.To exclude the correlations due to (1) or (2), we have to change both shields ( the shield with apertures and the screen) after each single particle. Hence, we should get only one point on every screen. Finally we should construct the histogram of points using a large statistical ensemble of screens with a single point on each of them. We predict that there should be no interference rings on this histogram or at least the interference should be very weak. Then we may realize experiments to separate hypothesis (1)-(3). For instance, we may change only screens after every experiment with a single particle. These experiments seem to be very simple from the theoretical point of view.

p-adic probability prediction of correlations between particles in the two-slit and neutron interferometry experiments
http://arxiv.org/pdf/0906.0509v1.pdf

I'm thinking there's a better explanation using Couder-type pseudo non-locality/memory effect where the wavelike behaviour of particle trajectories can result from feedback of the remote sensing of the surrounding world by the waves they emit. I thought it was also interesting that there are experiments that show that a time delay between photon release gets rid of the intereference pattern:

In one experiment, Kim et al. controlled the exact interval between independent signal photons emitted in pairs [12]. As the time delay between photons was increased, first-order interference gradually vanished. This shows that the interval between the quanta was more important than the state of the source for the final outcome...

Interpreting Negative Probabilities in the Context of Double-Slit Interferometry
http://arxiv.org/pdf/physics/0611043v1.pdf

 

[bohm2]

Indeed the Couder's experiments are amazing - giving a hope to get below the QM. I've participated in "Emergent Quantum Mechanics" conference in Vienna two years ago - he gave the opening talk and most of speakers expressed excitation about these experiments. If someone is interested, there is second edition (free admission) in a few weeks and Coder will be there: http://srv14116.omansrv14.omanbros.com/

Gerhard Grössing et al. have posted their slide presentation of this recent conference in this group's web page:

Relational Causality and Classical Probability: Grounding Quantum Phenomenology in a Superclassical Theory
http://www.nonlinearstudies.at/files/ggEmQM13.pdf

 

[JAWChemist]

Membrane

Assuming the Couder's experiments are a literal model the quantum particle world, then a logical extrapolation suggests some sort of vibrating membrane would be transferring energy to the particle. The choice of the word membrane was deliberate.

 

[StevieTNZ]

I believe Howard Carmichael, a Professor of Physics, pointed out that in Couder article they mentioned the oil droplet wasn't a quantum system, when I asked him.

 

[bohm2]

Assuming the Couder's experiments are a literal model the quantum particle world, then a logical extrapolation suggests some sort of vibrating membrane would be transferring energy to the particle.

You might want to search papers by Donatello Dolce on some possibilities:

http://www.ph.unimelb.edu.au/~ddolce/

 

[bohm2]

This paper came out today:

In 2005, Couder, Protiere, Fort and Badouad showed that oil droplets bouncing on a vibrating tray of oil can display nonlocal interactions reminiscent of the particle-wave associations in quantum mechanics; in particular they can move, attract, repel and orbit each other. Subsequent experimental work by Couder, Fort, Protiere, Eddi, Sultan, Moukhtar, Rossi, Molacek, Bush and Sbitnev has established that bouncing drops exhibit single-slit and double-slit diffraction, tunnelling, quantised energy levels, Anderson localisation and the creation/annihilation of droplet/bubble pairs.

In this paper we explain why. We show first that the surface waves guiding the droplets are Lorentz covariant with the characteristic speed c of the surface waves; second, that pairs of bouncing droplets experience an inverse-square force of attraction or repulsion according to their relative phase, and an analogue of the magnetic force; third, that bouncing droplets are governed by an analogue of Schrodinger's equation where Planck's constant is replaced by an appropriate constant of the motion; and fourth, that orbiting droplet pairs exhibit spin-half symmetry and align antisymmetrically as in the Pauli exclusion principle. Our analysis explains the similarities between bouncing-droplet experiments and the behaviour of quantum-mechanical particles. It also enables us to highlight some differences, and to predict some surprising phenomena that can be tested in feasible experiments.

Why bouncing droplets are a pretty good model of quantum mechanics
http://arxiv.org/pdf/1401.4356.pdf

Slideshow:
Forty-two? Ground-breaking experiments in the last 10 years
http://www.cl.cam.ac.uk/~rmb4/talk20131015.pdf

 

[bohm2]

Another interesting summary/overview of these experiments:

Fluid Tests Hint at Concrete Quantum Reality
http://www.simonsfoundation.org/quanta/20140624-fluid-tests-hint-at-concrete-quantum-reality/

The comments section is pretty interesting, particularly the discussion by Maudlin, Groessing and Anderson.

 

[atyy]

Another interesting summary/overview of these experiments:

Fluid Tests Hint at Concrete Quantum Reality
http://www.simonsfoundation.org/quanta/20140624-fluid-tests-hint-at-concrete-quantum-reality/

The comments section is pretty interesting, particularly the discussion by Maudlin, Groessing and Anderson.

What a crackpot article! The fluid experiments are only a mathematically analogous, and are not quantum experiments. Also, it insinuates that the pilot-wave theory is making a "come back" - how can it "come back" when it is already a leading solution to the measurement problem, and the only universally acknowledged solution without technical flaws for at least non-relativistic quantum mechanics. Many-worlds is also a leading approach, but it is not universally acknowledged to be without technical problems, even by proponents.

 

[TrickyDicky]

What a crackpot article! The fluid experiments are only a mathematically analogous, and are not quantum experiments.

What specific claim of the article do you find crackpot?

 

[nonequilibrium]

Another interesting summary/overview of these experiments:

Fluid Tests Hint at Concrete Quantum Reality
http://www.simonsfoundation.org/quanta/20140624-fluid-tests-hint-at-concrete-quantum-reality/

The comments section is pretty interesting, particularly the discussion by Maudlin, Groessing and Anderson.

I rather like this article, but it totally loses me at two points:

1. "If space and time behave like a superfluid, or a fluid that experiences no dissipation at all, then path memory could conceivably give rise to the strange quantum phenomenon of entanglement [...] But in the pilot-wave version of events, an interaction between two particles in a superfluid universe sets them on paths that stay correlated forever because the interaction permanently affects the contours of the superfluid."

   
   Firstly, how could the droplet model ever give rise to something mimicing entanglement? After all, while superpositions, quantization, etc are all quite quantum in nature, the TRUE quantum property is entanglement, and we know a classical (local) model, like the droplets, cannot exhibit entanglement. So what are they talking about?
   
   Secondly, in the second part, are they referring to pilot-wave theory as in de Broglie-Bohm theory (as opposed to the droplet analogy)? Because I don't see how pilot-wave theory explains entanglement as a kind of memory-effect.
   
2. space

   "In its current, immature state, the pilot-wave formulation of quantum mechanics only describes simple interactions between matter and electromagnetic fields, according to David Wallace, a philosopher of physics at the University of Oxford in England, and cannot even capture the physics of an ordinary light bulb."

   
   Why would Wallace say that? Surely pilot-wave theory/de Broglie-Bohm theory can explain at least as much as the conventional formulation, since the former contains all the results of the latter... (If David Wallace is claiming that there is no pilot-wave formulation for QFT, well, that's not true.)

Can anyone shed some light on either issue?

 

[atyy]

Another interesting summary/overview of these experiments:

Fluid Tests Hint at Concrete Quantum Reality
http://www.simonsfoundation.org/quanta/20140624-fluid-tests-hint-at-concrete-quantum-reality/

The comments section is pretty interesting, particularly the discussion by Maudlin, Groessing and Anderson.

Good to see that Maudlin had similar complaints about the article that I had!

 

[bhobba]

What a crackpot article! The fluid experiments are only a mathematically analogous, and are not quantum experiments. Also, it insinuates that the pilot-wave theory is making a "come back" - how can it "come back" when it is already a leading solution to the measurement problem, and the only universally acknowledged solution without technical flaws for at least non-relativistic quantum mechanics. Many-worlds is also a leading approach, but it is not universally acknowledged to be without technical problems, even by proponents.

Good to see that Maudlin had similar complaints about the article that I had!

What was it meatloaf said - oh yea - you took the words right out of my mouth.

Could not agree more.

Thanks
Bill

 

[bhobba]

Why would Wallace say that? Surely pilot-wave theory/de Broglie-Bohm theory can explain at least as much as the conventional formulation, since the former contains all the results of the latter... (If David Wallace is claiming that there is no pilot-wave formulation for QFT, well, that's not true.)

I think he is claiming a lot of work hasn't been done on pilot wave QFT - which is true.

Not sure if key theorems have been produced showing QFT as say detailed by Wienberg in his text on the matter is equivalent to a BM version.

Demystifier can probably give more detail.

Thanks
Bill

 

[Demystifier]

Demystifier can probably give more detail.

I've said much, so I will not repeat myself.

 

[TrickyDicky]

Good to see that Maudlin had similar complaints about the article that I had!

He also said he appreciated the article.
I agree with the critic about the pilot wave part, I don't think the experiments with droplets have much to do with de Broglie-Bohm theory except superficially,

The interpretation in relational terms by the Groessing group seems promising though.

 

[bohm2]

Good to see that Maudlin had similar complaints about the article that I had!

Ross Anderson in the comments section disagrees with Maudlin and argues that

...the droplet experiments do indeed allow you to visualise a pilot wave in the configuration space of two or more particles...we show that the standing wave created by the droplets bouncing on the vibrating bath is modulated with an analogue of the quantum mechanical wavefunction \psi; where there are two droplets it’s a function of the position and momentum of both of them. In fact you can see \psi with your naked eye in the pictures of the diffraction experiments.

He cites his paper:
Why bouncing droplets are a pretty good model of quantum mechanics
http://arxiv.org/pdf/1401.4356v1.pdf

But I had trouble following Anderson's argument even though I've read his paper previously. If anybody can follow Anderson's points, I'd appreciate their input.

 

[Hernik]

The group behind this study has not been able to reproduce Couder's double slit interference pattern from 2006.

In a paper from 2006, Couder and Fort [1] describe a version of the famous double slit experiment performed with drops bouncing on a vibrated fluid surface, where interference in the particle statistics is found even though it is possible to determine unambiguously which slit the “walking” drop passes. It is one of the first papers in an impressive series, showing that such walking drops closely resemble de Broglie waves and can reproduce typical quantum phenomena like tunneling and quantized states [2–13]. The double slit experiment is, however, a more stringent test of quantum mechanics, because it relies upon superposition and phase coherence. In the present comment we first point out that the experimental data presented in [1] are not convincing, and secondly we argue that it is not possible in general to capture quantum mechanical results in a system, where the trajectory of the particle is well-defined.

http://arxiv.org/pdf/1405.0466.pdf

henrik