When Fluid Dynamics Mimic Quantum Mechanics

[Daedalus]

It's very rare when our macroscopic world exhibits behaviour found in the quantum world. However, a team of researchers at MIT have found just that.

 

http://www.sciencedaily.com/releases/2013/07/130729111934.htm

 

In the latest issue of the journal Physical Review E (PRE), a team of MIT researchers, in collaboration with Couder and his colleagues, report that they have produced the fluidic analogue of another classic quantum experiment, in which electrons are confined to a circular "corral" by a ring of ions. In the new experiments, bouncing drops of fluid mimicked the electrons' statistical behavior with remarkable accuracy.

 

[studiot]

 

Note at the bottom of the article

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

 

I fear something important has been lost in the editing.

But thank you for raising the subject.

Edited August 1, 2013 by studiot

[Daedalus]

 

I fear something important has been lost in the editing.

But thank you for raising the subuject.

 

Most likely, there are several things lost in the editing. After all, it is science journalism, which can get things horribly wrong at times. However, the neat thing about what these scientists have done is to discover a real pilot-wave system, which adds support to Louis de Broglie's theory.

Edited August 1, 2013 by Daedalus

[studiot]

What I found interesting was that the article said the drop "bounced up and down" when it hit the liquid.

 

That implies that, although of the same material as the liquid, it did not coalesce with it. The drop must have been in some way identifiable as a drop.

I am still pondering the implications for the mechanics, in particular the surface tension.

[Daedalus]

What I found interesting was that the article said the drop "bounced up and down" when it hit the liquid.

 

That implies that, although of the same material as the liquid, it did not coalesce with it. The drop must have been in some way identifiable as a drop.

I am still pondering the implications for the mechanics, in particular the surface tension.

 

I'll see if I can find the papers that were suppose to be published in July that explain the fluid dynamics:

 

In a separate pair of papers, appearing this month in the Journal of Fluid Mechanics, Bush and Jan Molacek, another MIT graduate student in mathematics, explain the fluid mechanics that underlie the system's behavior.

 

The mathematics should be extremely interesting. I'm curious as to how much it might resemble or contrast with the Navier-Stokes equations regarding the fluid dynamics. As for the droplets, Physics Review E states:

 

Bouncing droplets can self-propel laterally along the surface of a vibrated fluid bath by virtue of a resonant interaction with their own wave field. The resulting walking droplets exhibit features reminiscent of microscopic quantum particles. Here we present the results of an experimental investigation of droplets walking in a circular corral. We demonstrate that a coherent wavelike statistical behavior emerges from the complex underlying dynamics and that the probability distribution is prescribed by the Faraday wave mode of the corral. The statistical behavior of the walking droplets is demonstrated to be analogous to that of electrons in quantum corrals.

 

It's also interesting how the physicists were able to produce the pilot-wave system:

 

In the experiments reported in PRE, the researchers mounted a shallow tray with a circular depression in it on a vibrating stand. They filled the tray with a silicone oil and began vibrating it at a rate just below that required to produce surface waves.

 

They then dropped a single droplet of the same oil into the bath. The droplet bounced up and down, producing waves that pushed it along the surface.

 

I found the original article released by MIT News that provides a little more detail regarding this pilot-wave system. They also provide this really awesome video showing the droplets in action:

 

The video is truly amazing!!! Very cool indeed!

Edited August 1, 2013 by Daedalus

[studiot]

 

The mathematics should be extremely interesting. I'm curious as to how much it might resemble or contrast with the Navier-Stokes equations regarding the fluid dynamics.

 

Surface tension is a separate treatment from Navier Stokes.

We combine them by introducing ST into the boundary conditions of the NS equations.

Edited August 1, 2013 by studiot

[Daedalus]

Surface tension is a separate treatement from Navier Stokes.

We combine them by introducing ST into the boundary conditions of the NS equations.

 

I realize that. I'm just curious as to how much NS was used to model the dynamics. Perhaps none at all, but it would be interesting to see the math. What's your thoughts on the video?

Edited August 1, 2013 by Daedalus

[studiot]

Interesting video.

 

But the effect is a surface effect (capillary waves) not a body effect so I don't see the NS equations as prominent.

 

What keeps the drop together? I speculate that its size is important (for a given fluid density and surface tension coefficient)

[Popcorn Sutton]

The droplet is silicon which is significantly more viscous than the water it is bouncing on. You can also cure the silicon to make it more solid.

[Daedalus]

The droplet is silicon which is significantly more viscous than the water it is bouncing on. You can also cure the silicon to make it more solid.

 

Actually, the droplet is the same liquid as it is bouncing on.

 

In the experiments reported in PRE, the researchers mounted a shallow tray with a circular depression in it on a vibrating stand. They filled the tray with a silicone oil and began vibrating it at a rate just below that required to produce surface waves.

 

They then dropped a single droplet of the same oil into the bath. The droplet bounced up and down, producing waves that pushed it along the surface.

Edited August 2, 2013 by Daedalus

[Popcorn Sutton]

My bad

[Daedalus]

My bad

 

It's all good... And in an unrelated matter, this was my 400th post. I am now a ninja Awe... just a molecule lol.

Edited August 2, 2013 by Daedalus

[gabrelov]

so cool so what are its possible applications in actual life, sorry I'm not a physics student but I want to learn more on physics.

[Daedalus]

so cool so what are its possible applications in actual life, sorry I'm not a physics student but I want to learn more on physics.

 

I'm not sure there are any direct applications that this can be applied to currently except extending our understanding of nature. Of course, I'm interested in studying the math and possibly doing the experiment myself.

Edited August 2, 2013 by Daedalus

[michel123456]

I have seen incidentally a similar effect in the jar of my electric coffeemaker.

[Daedalus]

I found the papers that were published in the Journal of Fluid Mechanics. I would've searched sooner, but I've been busy. Of course, there is a fee to access the papers, but I wouldn't mind making a purchase to see the details. Here's the abstract:

 

We present the results of a combined experimental and theoretical investigation of droplets walking on a vertically vibrating fluid bath. Several walking states are reported, including pure resonant walkers that bounce with precisely half the driving frequency, limping states, wherein a short contact occurs between two longer ones, and irregular chaotic walking. It is possible for several states to arise for the same parameter combination, including high- and low-energy resonant walking states. The extent of the walking regime is shown to be crucially dependent on the stability of the bouncing states. In order to estimate the resistive forces acting on the drop during impact, we measure the tangential coefficient of restitution of drops impacting a quiescent bath. We then analyse the spatio-temporal evolution of the standing waves created by the drop impact and obtain approximations to their form in the small-drop and long-time limits. By combining theoretical descriptions of the horizontal and vertical drop dynamics and the associated wave field, we develop a theoretical model for the walking drops that allows us to rationalize the limited extent of the walking regimes. The critical requirement for walking is that the drop achieves resonance with its guiding wave field. We also rationalize the observed dependence of the walking speed on system parameters: while the walking speed is generally an increasing function of the driving acceleration, exceptions arise due to possible switching between different vertical bouncing modes. Special focus is given to elucidating the critical role of impact phase on the walking dynamics. The model predictions are shown to compare favourably with previous and new experimental data. Our results form the basis of the first rational hydrodynamic pilot-wave theory.

Edited August 2, 2013 by Daedalus

[imatfaal]

I found the papers that were published in the Journal of Fluid Mechanics. I would've searched sooner, but I've been busy. Of course, there is a fee to access the papers, but I wouldn't mind making a purchase to see the details. Here's the abstract:

 

 

 

Here - have it for free on the website of one of the authors

 

http://math.mit.edu/~bush/wordpress/wp-content/uploads/2013/07/MB2-2013.pdf

 

Too many years as a student with acute financial problems (I always felt beer was more important than papers) made me pretty good at finding papers

[Daedalus]

 

 

Here - have it for free on the website of one of the authors

 

http://math.mit.edu/~bush/wordpress/wp-content/uploads/2013/07/MB2-2013.pdf

 

Too many years as a student with acute financial problems (I always felt beer was more important than papers) made me pretty good at finding papers

 

Thanks imatfaal!!! I really appreciate you finding that for me It's a cool experiment, and one that seems like it would be inexpensive to conduct. Of course, the most expensive part would be the camera used to take the video.

Edited August 7, 2013 by Daedalus

[imatfaal]

SwansonT is an amateur slo-mo cameraman - he may well be able to give tips on cheap(ish) equipment; although I don't think it is a hobby characterised by the simple and inexpensive equipment required!

[Daedalus]

SwansonT is an amateur slo-mo cameraman - he may well be able to give tips on cheap(ish) equipment; although I don't think it is a hobby characterised by the simple and inexpensive equipment required!

 

I meant inexpensive regarding everything else but the camera. From what I gather, high speed cameras cost a lot of money. Perhaps I can find a place that will rent one to me, or maybe the university will have one that I can use. Regarding your suggestion, I'll definitely have to ask SwansonT about some tips about purchasing cheap(ish) equipment.

Edited August 9, 2013 by Daedalus

[pantheory]

It's very rare when our macroscopic world exhibits behaviour found in the quantum world. However, a team of researchers at MIT have found just that.

 

http://www.sciencedaily.com/releases/2013/07/130729111934.htm

 

 

 

I perceive this "discovery" to be an important part of the "big banana."

 

Physical aether proponents like De Broglie and Maxwell would have loved to know of these results in their time, as the article implies. This below, I think, was a most relevant quote from the article concerning fluid dynamics and greatly improved quantum theory, concerning insights into the quantum world and parallels with the macro-world. .

 

"It's the first pilot-wave system discovered and gives insight into how "rational quantum dynamics" might work, were such a thing to exist."

 

I think this could be the beginning of rational changes to quantum mechanics/theory concerning the existence of a physical, aetherial type background field of some kind like De Broglie believed and asserted in his pilot wave theory. With such hypothesis such as dark matter, a Higgs field, gravitons, and many other possibilities, the existence of a physical background field of some kind, as being the basis for the observed effects in the quantum world, should not be that big of a surprise. I'm surprised I have not seen this information elsewhere!

 

Thanks for this interesting news posting my friend.

Edited August 11, 2013 by pantheory

[Daedalus]

 

I perceive this "discovery" to be an important part of the "big banana."

 

Physical aether proponents like De Broglie and Maxwell would have loved to know of these results in their time, as the article implies. This below, I think, was a most relevant quote from the article concerning fluid dynamics and greatly improved quantum theory, concerning insights into the quantum world and parallels with the macro-world. .

 

"It's the first pilot-wave system discovered and gives insight into how "rational quantum dynamics" might work, were such a thing to exist."

 

I think this could be the beginning of rational changes to quantum mechanics/theory concerning the existence of a physical, aetherial type background field of some kind like De Broglie believed and asserted in his pilot wave theory. With such hypothesis such as dark matter, a Higgs field, gravitons, and many other possibilities, the existence of a physical background field of some kind, as being the basis for the observed effects in the quantum world, should not be that big of a surprise. I'm surprised I have not seen this information elsewhere!

 

Thanks for this interesting news posting my friend.

 

You welcome! My thoughts on this is exactly the same. The work definitely suggests that there might exist a rational way to model quantum dynamics beyond the typical statistical approach.

Edited August 11, 2013 by Daedalus

[Strange]

I haven't seen any indication that this can model effects such as entanglement, though. It would be pretty exciting if it could.

[pantheory]

I haven't seen any indication that this can model effects such as entanglement, though. It would be pretty exciting if it could.

 

Hey strange,

 

I expect that you are correct. Entanglement would need a different explanation.as a separate conceptual obstacle to rational understandings of the quantum world. If you are interested in my simple "rational" explanation of Entanglement PM me. On the other hand maybe most of the possible conceptual problems might be corrected if the existence of a background field is confirmed and eventually incorporated into quantum theory.