Weird Surface Tension - Sixty Symbols
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- Опубліковано 1 гру 2012
- Sixty Symbols regulars Roger and James are part of a team investigating surface tension in granular systems. Their new paper is published at prl.aps.org/abstract/PRL/v109/...
Featuring Roger Bowley and James Clewett. Special thanks also to Mike Swift.
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At first I thought granular dynamics sounded really boring, but the more of this guy's work I see, the more interesting it gets.
Well glad you found it!
The extra footage is not yet live - it will be on the nottinghamscience channel where most of my "extras" go!
Turns out there are also big mysteries in physics which are NOT about quantum events, multiverses, the origin of everything etc., stuff we thought we knew turns out te be mysterious as well! Science at its best :D
Classical mechanics isnt an easy topic by any possible means.
Thanks a lot for doing this, Brady.
And thanks professors of nottingham for being so open and taking your time to give insight like that!
8:34 I thought there would always be brazil nuts at the top because his cereal is shaken in a gravitational field. The small bits have an easier time finding gaps they can fall down through so the cereal ends up being stratified by particle size. The same with rocks floating to the surface when they're in an environment with sufficient vibration and low viscosity. Don't know if that's right but that was always my understanding. I wonder how his cereal would be in a microgravity environment?
A brilliant, throught-provoking piece. Congratulations to Roger and James on recognition of their research!
Some of the picture on 3:38 reminds me of the Cosmic background radiation pictures. Some surface tension like effects in play there, too? Anyone ever though about that?
+MrMegaPussyPlayer Yes it reminded me too. It might be the case that similar (or same) process was forming our universe too. I have also loaded old comments and there I found a mention that these patterns are displaying Spinodal Decomposition, not that I understood more than introduction on the wiki page, but still very interesting.
photons don't have surface tension. you're just seeing vaguely similar patterns because both systems are influenced by random fluctuations.
i say vaguely because here (and in the decomposition of a water and oil mixture, for instance) you've got two separate 'states'. In the CMB there's a (continuous) gradient of temperature.
MrMegaPussyPlayer: I thought the same thing, too!
Yes
With the assumption of having a deterministic system, and we assume that we have gravitationally induced superluminal motion of photons, we can have a kind of interference that thermodynamically changes the system by information bearing, sth like surface tension
Thanks for the prompt reply, that's fantastic news - great to hear. I was going to say wish him luck from me, but it sounds like James will not need it. It is wonderful to see you on video again too Professor, your passion for physics and compassion for others is very uplifting to see.
Thanks so much for sharing your research with the public like this.
Amazing stuff! I wish more people would report about cutting edge research like this, directly interviewing the very people who research it.
I'd also love to see a more advanced explanation of it all. These two videos are perfect to make me super-interested. Now I'd love to hear more details.
Are you sure that those cows did not make it into the journal? That was a great animation.
James and Roger's videos are my favorite!
Hi "sixtysymbols" is that you Brady?? Great to see Prof. Bowley and James in a video again. It's uplifting to see they are leaving their mark on the world. I was wondering how did James go with his PhD, I remember watching a video where he so generously gave us an insight into his personal life and explained how he was hand writing it. Has he finished yet??
Absolutely incredible! As a college physics major I look forward to working on these problems!
Well done guys, this is awesome and I'm really happy for you :)
This is a fascinating discovery. Cheers guys!
Congratulations on the Paper! (great video).
Kudos chaps, that's really fascinating!
A few things...
1) Congratulations!
2) Perhaps in another episode talk about the applications/implications of the experiment.
3) The organization of the sand reminds me of WMAP pictures.
4) Could this surface tension experiment be caused by quantum gravity?
Keep up the good work guys!
I'm no expert - but these aren't molecules, they're (on the atomic scale) great big pieces of copper and they certainly make noise when they rattle around!
Did the graphic at 6:13 mindfuck anyone else or am I just that tipsy right now? Like, I . . . what
gumenski It's just scaled weirdly. If you stretched it up vertically or squashed it horizontally, to make the video more of a square shape, then your brain would find it much easier to figure out what perspective it's from.
No, noone else.
I think the reason this experiment is relevant is because the pattern is displaying Spinodal Decomposition, not just a visualization of the well-documented nodal patterns in Chladni Plates.
so the result of this experiment is *different* from just a standing wave forming in the box forcing the grains in certain fixed patterns which depend on the frequency applied (60hz mentioned here)?
You're thinking of the vibration nodes experiment. A very different effect due to the lower frequency of the vibrations. One was about standing waves in 2 dimensions and the patterns they make. This is about the interaction of the particles without standing waves or nodes. The patterns will always change in this experiment.
You've made some really good and valid points there.
"The theory is simply ridiculous"
"It's laughable"
I myself can't imagine more solid proofs of big bang theory's inconsistency
I watched a video recently about how a foam pattern can be measured at every observable scale, from a molecular reference to an interstellar reference we see these polygons forming patterns, and I can't help but notice the similarity between that, and the first picture he showed of the bronze 1/3 of a second after the vibrations started.
This is aweseom! (: good work!
Any particular reason why brass was used and not some other material? Keep up the great work Brady & team!
Fantastic video, btw. (as usual!).
What frequency are you shaking the box? Did you try changing the frequencies? Thank you
Awesome! And - CONGRATULATIONS!
it is amazing how much the slides in the first 1/3 of a second looks like the WMAP data.
Well done guys!
@sixtysymbols, are Roger and James familiar with the work of Dr. Gerald Pollack? There's a video of him here on UA-cam from 2009, presenting his findings on the liquid-crystal structure of water. He talks at length about surface tension and how energy imparted by light creates a charge separation in the surface of water. I'd love to hear more about this, it's very cool.
That is amazing. I wonder if that affect plays any part in star formation or indeed galaxy seeding in the early universe?
Thanks for clarifying this. I come from the field of electrical engineering, and sadly, we too often take things for granted. I just hadn't realized there was until now no real theory behind these patterns.
I remember a fairly recently episode of QI (that's Stephen Fry's current show for those who don't watch the BBC) where there was a question nobody apparently knows about why certain nuts rise to the top of a group of mixed nuts. I thought it was odd we didn't fully understand the physics at the time, but I'm starting to see now that random mixed objects being shaken up is quite a bit more complicated than it initially appeared (and the way it initially appears seems complicated enough as it is).
Yeah but its always good to ask questions and have and ideas of your own even if its on a very fundamental level, and I'm curious what they did take in to a count when running the simulation, because I work with particle/fluid dynamics professionally. (;
This is really exciting. Wish the video was more elaborate
the experiment was based on previous experiments with ferrous liquids and just water in a closed box with varied levels of hertz pumped though. the expected reaction for liquids is to stick together, its chemical. and so when they are shaken, we see patterns depending on the level of hertz. with dry granules, there is no chemical bond between each other, so they don't try to clump together. so its just the context of the experiment which explains why testing environments don't affect the result.
Well done team!!!
"It's ironic that you choose that example...because you HAVE. That's exactly what you've done."
Made my day :D
Not too sure if this applies to the video but you guys know about those colored sands in a bottle you get at fairs sometimes? They say in the video we can't shake things to make them uniform but if you shake a bottle like that it spreads pretty uniformly. Or can you arrange the colors in a certain pattern that will retain a lot of uniformity?
It's rather unfortunate that James doesn't show up a lot on Sixty Symbols, I like how he explains stuff.
They tell us that density is what matters if it sinks or not. But according to these vods you also have to add some extra force to win from the surface tension.
Kind of like the latent energy required to change from phase to phase.
mind-blowing stuff as always, THANKS 60 SγMBΦLS!!
Like some others have said, it would interesting to see the outcome with different set frequencies and do the patterns or behavior change with a sweeping frequency.
awesome,and congrats
At some points of the experiment it looks like little menisci are forming. So I guess there are adhesive effects with the walls accompanying the cohesive effects of the particles. Do you see these in the simulation (if you include inelastic walls)?
Amazing stuff. Michael
fair enough, thank you for explaining!
Ever since your first video on Granular Dynamics I have been extremely interested in the concept, and am really curious as to how the system mimics the characteristics of other phases, primarily gas. It seems almost as if you are creating a gaseous system but with bigger particles. Does the system mimic any gas laws? (ex. solubility, ideal gas law)
Partially, but also static charging would probably have a lot to do with it. There was an experiment done with a bag of salt in low gravity, and when they shook it, the grains tended to clump together and stay that way. Looks like what happens here is that by denying the particles a stationary surface on which to settle, and keeping them all constantly moving, it's turning them into a kind of fluid. The surface tension then forms because any concave curve would trap particles faster than convex.
how do separate this effect from other effects due to standing wave patterns in the box? If this is driven at a constant frequency you would expect to see chladni patterns
He has typed up his thesis and has handed it in to be assessed. The oral examination is in January and will be conducted by Professor Brilliantov of Leicester University, a leading expert in the field. He should pass the examination, for James is very good at expressing his ideas; and he works hard.
The research has changed in character in the last 12 months so his hand written notes, although useful, have proved less useful than he hoped.
Roger Bowley
Congrats on the having the work accepted guys =)
@rebenergy:
I think so. Since the particle shape influences the collision behavior it should affect the resulting shapes.
I wonder how this is surface tension when energy is being put into the system that causes the behavior. Interesting enough the surface tension of any material (including water) can be changed by changing the frequency and amplitude of vibration. Thank you again for the video!
Yours is a very good description of surface tension arising from forces between molecules. Knowing how molecules behave gives us a way of understanding surface tension.
But grains of bronze do not have such forces. Their surface tension emerges from the collective motion of all the particles so that, in the interface region, the kinetic energy component parallel to the interface is not the same as the kinetic energy component perpendicular to the surface. This is our new idea.
Your experiment looks like Chladni figures, that I use in tuning an musical instrument's soundboard. What is the relationship between the "surface tension" and the nodal mapping of vibrating plate? Is what you are observing the result of the interaction (attraction of the particles) due to the "surface tension" or the collecting of particles at a plate's nodal lines for a given frequency?
It seems to me that vibration and tension are in some way intrinsically connected. These granules display properties of surface tension when vibrated, comparably, a guitar string will only vibrate when under tension?
I think the purpose of the experiment is basically saying that we can treat groups of large pieces of matter, when they are all basically uniform, as if they were liquids. If you really get in very very close, water does not have a surface, it is just a collection of molecules that are attracted to each other by electromagnetism. From a slightly larger reference frame, these pieces of sand also do not have a surface, and yet they attract each other just like water.
The experiment was done many times and after mastering the method we took 20 runs that had no flaws in them --- for example if the cell is not level the centre of mass of all the grains drifts to one side so we excluded those runs.
The locations were always different.
That's a good question. My instinct says that there isn't a direct analog; in water surfactants work based on polarity, which isn't at play here. However, I guess since what's causing the surface tension in this case is a loss of kinetic energy, if you could introduce something that would coat the particles and make them more elastic when the collided (some sort of "flubber" if you've seen that movie) you might be able to achieve the same effect.
This research seems quite related to research on cement mixing: how does one best stir wet cement to keep the mixture consistent, and minimize the formation of dry clumps and cement dry out.
How well does Gauss's divergence theorem predict these behaviours?
Hey Brady, if you get a chance to ask;
Can this shaking motion be used to separate out the components of a powder / granular medium? Like, for example, I had a mixture of salt and sugar and shook it at the right frequency; would the two components move over into individually distinct blobs / phases?
I'm glad I wasn't the only one who immediately thought 'Turing reaction-diffusion pattern' as soon as he turned the system on! I've simulated such patterns before and it looks precisely like them!
So it is, how glorious! I was referring to the other two granular systems videos.
Does the behavior of the particle change markedly if there is a variety of varying sizes of beads?
I am interested to know what role air pressure plays in the solid matter surface tension, especially on your vibrating table.Would the grains moving away from each other should create a low pressure area that will attract more grains? This would help explain why there are circular groups that will eventually end up together. Just a though
6:58, OE...
Only thing i could think of was OE-cake which is a physics simulation sandbox "game".
This too deals with surface tension quite a lot and is really fun to play around with.
Those are some marvelous cows Brady. :-) You should auction the picture next time there is a MCF 24 hour event in the youtube science and skepticism community.
Water has higher surface tension than most common liquids. The strength of the surface tension is based on intermolecular forces (the electrostatic forces between the molecules themselves) and water happens to have pretty strong intermolecular forces. These same forces determine boiling point, so a good way to find liquids with stronger or weaker surface tensions would be to compare their boiling points. A higher boiling point usually means stronger surface tension.
So, would I be correct for intuiting that like grain sizes would attract and be attracted to like because they share something akin to "potential frequencies"? further assuming I might be near to correct would this be analogous, in any way, to the different surface tensions of D2O and H2O?
Just some meanderings...
So, here is a question: The surface tension in the case of cows (or celestial bodies and gravity) is present because every single particle has an inclination to go towards the center. A side effect of this inclination is that it tends to erase any asymetry, so if a big object comes pushing in, displacing them from circular formation, their "collective need" of being symmetrical will push back. What mechanic is behind the copper dust's need to be in circular lumps?
If the bronze particles are too small then air certainly has an effect. We chose the grains so that they were sufficiently large that we hoped the air effects were negligible.
The computer simulations were based on the idea that the air effects were negligible, so we only included inelastic collisions between spheres. The behaviour shown in the simulations reproduces what is observed in experiment.
Trying to create a vacuum in the cell caused the glass cell to implode.
Bronze is also an alloy. I would try the same experiment with particles composed of a pure element. There is also a mechanism of particle migration/movement in suspension called shear migration (A, Acrivos)
Two questions, have these experiments been tried in a near vacuum environment to reduce the interaction with air molecules, or is it minimal to begin with? Secondly, if the solid particles behave like fluids with surface tension, do they also have a "vapour" pressure? Does heating up the set up alter the behaviour of the particles?
I wanted to watch that extra footage wideo with the insides of that computer, but when i clicked on the link it wasn't on the Test Tube channel that was linked to.
I am disappoint.
Hope it will be there soon.
Don't every particle have a its own gravity force that pull on each other and make them cluster together, or is that force to weak to affect the particles that fast? and also could it be electrostatic energy that attract the particles together?
Reminds me of the videos of a slurry of magnetic particles in liquid dancing on a speaker (there a many on youtube). You see the slurry form all kinds of vertical shapes that seem to defy gravity - which is an aspect of surface tension, right? Very interesting.
Isn't that fenomenon explained by the sound frequencies the particles are exposed to? There are plenty of experiments with grains of salt or sand arranging in changing shapes, when the vibrating plate they sit on is vibrated at different sound frequencies. This looks rather similar to that
interesting. I worked in a soils lab a few years ago where we had to break, shake, soak, compact, and do many things to the soil. Shaking it was one of the most common. I wish I had known this so I could have looked out for it
In a way, I think both sound an heat can be regarded as kinetic energy. For sound, a medium such as air forms waves of denser and less dense areas. Heat is just the average of shaking or vibration of the individual molecules.
In this case here, the energy is given off the bronze particles/ water molecules to the surrounding medium (i.e. air), I wasn't sure if you considered that.
I only took a quick look, but aren't those two different experiments? In this one the whole plate(I think) is vibrated up and down to agitate the grains. In the video you suggested all it showed was sand settling at the nodes of vibration of a standing wave pattern in a piece of metal? When they said they vibrated the plate at 60 Hz I think they meant up & down vs setting up a 60 Hz standing wave. pattern.
Hello,
How do you recommend a person/scientist/me goes about mixing something then? I am using McMaster's work to model spinodal decomposition during spin-coating, and I am just squiffy enough to think that a youtube request to you will help me out! Lovely video, thanks so much.
I would try the same experiment in the presence of a vacuum. What is the effect of the air molecules? What is the surface charge of the bronze particles ?
Surface tension can also appear in hard disk and hard sphere systems that both undergo a first order phase transition from fluid to solid. I therefore wonder if dissipation is so crucial in this nice experiment with granular matter...
Well....as I take as implied in the demonstration, bronze particles DON'T produce any surface tension UNLESS a continuous vibrating upward force is applied. That, ultimately, has to be the source of the force of the surface tension. There HAS to be some component of lateral force from the imperfect vibration mechanism--and that supplies the lateral force that moves the particles from which the surface tension emerges.
In response to your brazil nut example. Consider this. The hardware store I work in has a paint department. When we need paint tinted, we put in the colorant, then shake the paint up and down in the exact same way (I know some swirl it, some shake it in 3 dimensions, but ours is JUST up and down.) The paint, after only a coupe minutes, has a completely even color. Why doesn't the colorant separate and pool in one area of the medium?
congrats guys! keep up the good science
should this be done with more grain types in the "plate"? like grain of coper and nickel or so. Maybe 2 grain wich are chemically very close to each other already and look if it clusters as much as other things etc.. I found this quite interesting matter!
I want to conduct this experiment for a high school science fair project. I want to know a little bit about the setup and the cost of it. I would appreciate it if you could help me! What were the steps in making the square box? How much would a piston cost? Could I connect the piston to any sort of wave generator? Is the computer simulation necessary to conduct the experiment. What resources and sources of information do you think could use to conduct the experiment?
See the Brazil Nut Effect (sixtysymbols) video Brady put in the video responses above. It is very relevant to your question.
Maybe the vibrations induce a resonance in the particles which creates some sort of interference pattern with the source vibration waves. You then have waves from the particles themselves pushing against the source waves, pushing the partials to clump into this pattern.
Similar to a magnet inducing an EMF in a metal which creates an opposing magnetic field which propels the magnet itself.
are there different outcomes if you vibrate at different values ?
Amaaaaaazing!
The underlying cymatics and the triboelectric and tribomagnetic effects have presumably been discounted?
They got even distribution by shaking at one frequency and/or amplitude and clumpy shaking a different way. I saw a video once about this and they said that drug companies and livestock feed companies use vibration at certain frequencies to create clumps of their product for easier storage.