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?
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!
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
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.
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.
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!
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??
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.
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.
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.
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.
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.
@sixtysymbols, are Roger and James familiar with the work of Dr. Gerald Pollack? There's a video of him here on TH-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.
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.
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.
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).
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...
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?
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
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?
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.
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.
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.
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.
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?
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.
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?
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.
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.
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.
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.
The thing those two have in common is that particles of some sort are building clusters due to attractive forces. But that's where the similarities end. Surface tension means that there is also an outward pointed force (like with the paper clip on water) which repels objects. This effect is not present in the case of galaxy fomation. The formation depends on gravity alone and has no surface tension like behavior. Thanks for the great question, made me think a bit.
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.
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.
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. (;
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
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)
We had the same problem initially. The computer simulation allows us to calculate the pressure inside and outside the circular blob and the pressure difference varies at sigma/r, that is the surface tension divided by the radius; the second method uses a flat interface and involves the difference between the pressure, P, in the direction perpendicular to the interface less the pressure parallel to the interface. Both methods give the same sigma. Weird Huh.
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.
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.
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.
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?
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
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
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?
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.
Good question. The surface tension does not come from forces between particles: it comes from the collective motion of all the particles, in particular their components of kinetic energy. It is an emergent property that does not come from the behaviour of individual particles. Atoms obey the laws of quantum mechanics. A large enough collection of atoms can form a solid which moves in space according to the laws of Newton. Newton's laws emerge from the collective motion of many particles (solid).
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!
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.
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)
They don't say whether the experiment is carried out in vacuum or with gas, but I'd assume that in a vacuum the clumping would take a little bit longer because you've removed one way to lose energy, which is air resistance.
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 ?
I'm pretty sure that resonance not only requires that the frequency was constant, but also that it was some specific frequency. In the experiment they probably chose a frequency that is far from resonance frequency.
That's very interesting. What would happen if you put more then one type of sand with different densities, sizes, materials ect? Would they randomize together or cluster with their similar grains?
Water takes 40 kJ/mol of energy to go from liquid to gas, once it's already at 100 degrees Celsius. This equates to slightly more than 2,200 kJ per kg (or 1000 per lb). ONE kJ (kilo-Joule) is how much energy a 100W lightbulb uses in 10 seconds, or lifting a 200 lb. weight about one meter (~3 feet) off the ground. Raising water by one degree takes about 4kJ per kilogram. Different materials require different amount of energy, though, which is why metals often feel more hot or cold.
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
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!
do you think this surface tension and the tendency for matter to regroup has anything to do with the latest discovery of the huge structure in the universe that you just covered in one of your videos? It would be interesting to hear what the professors think about the link between the two situations.
That's true, but the scale of these disturbances is very small, but as time goes on these disturbances scale up, resulting in bigger clusters and a kind of breaking in the symmetry of the system.
This is very exciting. I have been working in separations technology mainly membrane separations. I realize these anhydrous particles but my question is: Is it possible that this discovery might help flocculate suspended particles down to sub-micron sizes 0.1 to 1.0 microns? Chemical polymers are now used with High Cationic Properties to merge animal waste particles together prior to decanter centrifuges. What vibration cycle would be required for waste particles in 98% water?
You're looking at it from an outside perspective, our universe could currently be a tiny spec so its irellevant. Especially as all that has ever existed was inside the spec so any dimensions of size cannot be thought as such.
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?
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.
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...
I don't know if you use these operations here (I know it's used in fluid dynamics) but could you please do a video explaining what gradient, divergence and curl mean physically (the last two are particularly hard for me. Explaining it in a comment would be great too!). I can do the math i.e. solve problems but find it quite hard to get a sense of what it all means. I need to use these in electromagnetism. As an engineer what I can do is more or less enough but it's not very satisfying.
The surface is vibrated creating nodes and anti-nodes. The brass dust clusters towards the anti-nodes. and as the dust moves it changes the surface which changes the location of the nodes and anti-nodes. The system seeks the lowest energy state resulting in the dust clustering as one
@scampc: Gravity is much too weak (tens of orders of magnitude) to have any impact on behavior of small particles. In the video it is explained with the loss of kinetic energy due to collisions. I'm no expert in the field of particle motion, but it sounds at least possible.
I'm a little confused. This and a few other videos (bouncing balls and Brazil nut effect) say that a system in which particles are in constant random motion will have the particles group together. While studying diffusion current in semiconductors I learned that the opposite happens - a concentration gradient becomes uniform. What's the difference between the two systems for them to behave differently?
An effect of surface tension is that the particles of a cluster "stick together" which results in an outward pointed force,like you can see with the already mentioned paper clip.It floats,because there is an outward pointed force. And galaxy formation does not depend on a similar force like the one on the paper clip. Surface tension has nothing to do with that, it only depends on gravitational attraction. BTW this is only yt and i can't give a complete description of surface tension in a comment
You did a video very similar to this (60 Hz vibrational starting point, small glass box, cohesive forces moving particles together) which was published as a paper (according to what James says in the video): watch?v=HKvc5yDhy_4 What exactly is the field of study that you are using these findings for? What are the applications of "weird surface tension" or silica granules vibrating at 60hz? And what were the differences in these papers, experiments and findings?
So is surface tension in water explained more by the mechanical interactions of the molecules colliding than we thought and less by the electrical attractions between the molecules, or is that not what you are saying at all?
you can actually quite reasonably explain this behaviour using chaos theory and strange attractors, you should try and get data from other other materials, try substituting the glass with a polymer such as perspex, vary temp and pressure.
Well glad you found it!
At first I thought granular dynamics sounded really boring, but the more of this guy's work I see, the more interesting it gets.
The extra footage is not yet live - it will be on the nottinghamscience channel where most of my "extras" go!
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?
Thanks so much for sharing your research with the public like this.
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!
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!
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 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.
A brilliant, throught-provoking piece. Congratulations to Roger and James on recognition of their research!
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.
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!
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??
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.
James and Roger's videos are my favorite!
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.
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.
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.
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.
@sixtysymbols, are Roger and James familiar with the work of Dr. Gerald Pollack? There's a video of him here on TH-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.
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.
Are you sure that those cows did not make it into the journal? That was a great animation.
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.
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).
Absolutely incredible! As a college physics major I look forward to working on these problems!
it is amazing how much the slides in the first 1/3 of a second looks like the WMAP data.
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...
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?
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
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?
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.
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.
Any particular reason why brass was used and not some other material? Keep up the great work Brady & team!
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.
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.
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?
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.
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?
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.
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.
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.
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.
The thing those two have in common is that particles of some sort are building clusters due to attractive forces.
But that's where the similarities end. Surface tension means that there is also an outward pointed force (like with the paper clip on water) which repels objects. This effect is not present in the case of galaxy fomation. The formation depends on gravity alone and has no surface tension like behavior.
Thanks for the great question, made me think a bit.
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.
"It's ironic that you choose that example...because you HAVE. That's exactly what you've done."
Made my day :D
mind-blowing stuff as always, THANKS 60 SγMBΦLS!!
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.
That is amazing. I wonder if that affect plays any part in star formation or indeed galaxy seeding in the early universe?
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. (;
See the Brazil Nut Effect (sixtysymbols) video Brady put in the video responses above. It is very relevant to your question.
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
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)
We had the same problem initially. The computer simulation allows us to calculate the pressure inside and outside the circular blob and the pressure difference varies at sigma/r, that is the surface tension divided by the radius; the second method uses a flat interface and involves the difference between the pressure, P, in the direction perpendicular to the interface less the pressure parallel to the interface. Both methods give the same sigma. Weird Huh.
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.
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.
This is a fascinating discovery. Cheers guys!
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.
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?
@rebenergy:
I think so. Since the particle shape influences the collision behavior it should affect the resulting shapes.
The underlying cymatics and the triboelectric and tribomagnetic effects have presumably been discounted?
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
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
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?
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.
Kudos chaps, that's really fascinating!
Good question. The surface tension does not come from forces between particles: it comes from the collective motion of all the particles, in particular their components of kinetic energy. It is an emergent property that does not come from the behaviour of individual particles.
Atoms obey the laws of quantum mechanics. A large enough collection of atoms can form a solid which moves in space according to the laws of Newton. Newton's laws emerge from the collective motion of many particles (solid).
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!
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.
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)
They don't say whether the experiment is carried out in vacuum or with gas, but I'd assume that in a vacuum the clumping would take a little bit longer because you've removed one way to lose energy, which is air resistance.
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 ?
I'm pretty sure that resonance not only requires that the frequency was constant, but also that it was some specific frequency. In the experiment they probably chose a frequency that is far from resonance frequency.
Search Cymatics to see more, changing the frequency of vibration effects the pattern of distribution.
That's very interesting. What would happen if you put more then one type of sand with different densities, sizes, materials ect? Would they randomize together or cluster with their similar grains?
Water takes 40 kJ/mol of energy to go from liquid to gas, once it's already at 100 degrees Celsius. This equates to slightly more than 2,200 kJ per kg (or 1000 per lb). ONE kJ (kilo-Joule) is how much energy a 100W lightbulb uses in 10 seconds, or lifting a 200 lb. weight about one meter (~3 feet) off the ground. Raising water by one degree takes about 4kJ per kilogram. Different materials require different amount of energy, though, which is why metals often feel more hot or cold.
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
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!
Well done guys, this is awesome and I'm really happy for you :)
Have you tried the same experiment with different materials, granular sizes etc?
do you think this surface tension and the tendency for matter to regroup has anything to do with the latest discovery of the huge structure in the universe that you just covered in one of your videos? It would be interesting to hear what the professors think about the link between the two situations.
That's true, but the scale of these disturbances is very small, but as time goes on these disturbances scale up, resulting in bigger clusters and a kind of breaking in the symmetry of the system.
This is very exciting. I have been working in separations technology mainly membrane separations. I realize these anhydrous particles but my question is: Is it possible that this discovery might help flocculate suspended particles down to sub-micron sizes 0.1 to 1.0 microns? Chemical polymers are now used with High Cationic Properties to merge animal waste particles together prior to decanter centrifuges. What vibration cycle would be required for waste particles in 98% water?
You're looking at it from an outside perspective, our universe could currently be a tiny spec so its irellevant. Especially as all that has ever existed was inside the spec so any dimensions of size cannot be thought as such.
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?
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.
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...
I don't know if you use these operations here (I know it's used in fluid dynamics) but could you please do a video explaining what gradient, divergence and curl mean physically (the last two are particularly hard for me. Explaining it in a comment would be great too!). I can do the math i.e. solve problems but find it quite hard to get a sense of what it all means. I need to use these in electromagnetism. As an engineer what I can do is more or less enough but it's not very satisfying.
The surface is vibrated creating nodes and anti-nodes. The brass dust clusters towards the anti-nodes. and as the dust moves it changes the surface which changes the location of the nodes and anti-nodes. The system seeks the lowest energy state resulting in the dust clustering as one
Awesome! And - CONGRATULATIONS!
@scampc:
Gravity is much too weak (tens of orders of magnitude) to have any impact on behavior of small particles. In the video it is explained with the loss of kinetic energy due to collisions. I'm no expert in the field of particle motion, but it sounds at least possible.
So it is, how glorious! I was referring to the other two granular systems videos.
Congratulations on the Paper! (great video).
Looks a lot like Reaction Diffusion patterns. Am I way off or is there a reason that wasn't mentioned in the video?
I'm a little confused. This and a few other videos (bouncing balls and Brazil nut effect) say that a system in which particles are in constant random motion will have the particles group together. While studying diffusion current in semiconductors I learned that the opposite happens - a concentration gradient becomes uniform. What's the difference between the two systems for them to behave differently?
An effect of surface tension is that the particles of a cluster "stick together" which results in an outward pointed force,like you can see with the already mentioned paper clip.It floats,because there is an outward pointed force.
And galaxy formation does not depend on a similar force like the one on the paper clip. Surface tension has nothing to do with that, it only depends on gravitational attraction.
BTW this is only yt and i can't give a complete description of surface tension in a comment
You did a video very similar to this (60 Hz vibrational starting point, small glass box, cohesive forces moving particles together) which was published as a paper (according to what James says in the video):
watch?v=HKvc5yDhy_4
What exactly is the field of study that you are using these findings for? What are the applications of "weird surface tension" or silica granules vibrating at 60hz? And what were the differences in these papers, experiments and findings?
So is surface tension in water explained more by the mechanical interactions of the molecules colliding than we thought and less by the electrical attractions between the molecules, or is that not what you are saying at all?
you can actually quite reasonably explain this behaviour using chaos theory and strange attractors, you should try and get data from other other materials, try substituting the glass with a polymer such as perspex, vary temp and pressure.