Weird Surface Tension - Sixty Symbols

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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[@dormirenonpotest]

At first I thought granular dynamics sounded really boring, but the more of this guy's work I see, the more interesting it gets.

[@maartendj2724]

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

[@mikhailmikhailov8781]

Classical mechanics isnt an easy topic by any possible means.

[@MrMegaPussyPlayer]

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?

[@msjr71]

+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.

[@calinguga]

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.

[@shruggzdastr8-facedclown]

MrMegaPussyPlayer: I thought the same thing, too!

[@Hello-xk9pi]

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

[@gumenski]

Did the graphic at 6:13 mindfuck anyone else or am I just that tipsy right now? Like, I . . . what

[@techy4198]

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.

[@Kram1032]

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!

[@Saki630]

Are you sure that those cows did not make it into the journal? That was a great animation.

[@TheGreyfoo]

A brilliant, throught-provoking piece. Congratulations to Roger and James on recognition of their research!

[@eeellbee]

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.

[@maitland1007]

Thanks so much for sharing your research with the public like this.

[@Kram1032]

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.

[@MrMichaelEdie]

James and Roger's videos are my favorite!

[@bigboam]

This is a fascinating discovery. Cheers guys!

[@chlomosaurusrex]

Well done guys, this is awesome and I'm really happy for you :)

[@hydrophiliak]

Kudos chaps, that's really fascinating!

[@jakevikoren]

Absolutely incredible! As a college physics major I look forward to working on these problems!

[@sixtysymbols]

Well glad you found it!

[@eeellbee]

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??

[@johnrae4529]

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!

[@falconlara]

Congratulations on the Paper! (great video).

[@Candyliz2003]

Awesome! And - CONGRATULATIONS!

[@DaveTapley]

Well done guys!

[@QUARKyNERD]

Fantastic video, btw. (as usual!).

[@MrOldprof]

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.

[@WhitentonMike]

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.

[@theAmdisen391]

This is aweseom! (: good work!

[@EamonBurke]

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.

[@mynameismatt2010]

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.

[@MrSnickerssuper]

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

[@kenfury23]

it is amazing how much the slides in the first 1/3 of a second looks like the WMAP data.

[@kousoulides]

mind-blowing stuff as always, THANKS 60 SγMBΦLS!!

[@pouelchnu]

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.

[@jakevikoren]

Well done team!!!

[@RimstarOrg]

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?

[@thomasredman6038]

awesome,and congrats

[@sixtysymbols]

The extra footage is not yet live - it will be on the nottinghamscience channel where most of my "extras" go!

[@MrMichaelEdie]

So it is, how glorious! I was referring to the other two granular systems videos.

[@timewass]

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.

[@Angaraman]

fair enough, thank you for explaining!

[@MrPauld123456]

That is amazing. I wonder if that affect plays any part in star formation or indeed galaxy seeding in the early universe?

[@swiminbandgeek]

Congrats on the having the work accepted guys =)

[@jjj00j97]

funny thing is, as human , we also group together when there is earthquake. ööö

[@julioequinones]

🤣🤣🤣, That is true...

[@duffman18]

j jj00j I'm not kidding here, but there's been a few studies about crowds of people, and how if you treat each person as a molecule, the whole crowd basically behaves like water.

[@crackedemerald4930]

Fluid dynamics is the science of lots of little things flowing, could be molecules, could be a rockstar show crowd

[@SC-zq6cu]

@@duffman18 60 symbols have explored that. See "physics of moshing" by 60 symbols.

[@Kanawanu]

Same effect has been observed on the oscillating pedestrian bridge in London. While the amplitudes were increasing people were crowding to each other countering with horizontal movement and counter to their intuition they added up to amplitude and cause even more damage.

[@Stue-e]

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.

[@christronomatic]

congrats guys! keep up the good science

[@chopperboi89]

Any particular reason why brass was used and not some other material? Keep up the great work Brady & team!

[@RealCadde]

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.

[@Shive1337]

This is really exciting. Wish the video was more elaborate

[@brandy1011]

"It's ironic that you choose that example...because you HAVE. That's exactly what you've done." Made my day :D

[@Patan77xD]

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. (;

[@rayp526]

Bravo Nottingham. Bravo!

[@otakucode]

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!

[@MrMichaelEdie]

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

[@MrOldprof]

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.

[@Truthiness231]

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).

[@SussyBacca]

Amaaaaaazing!

[@ARiverSystem]

@rebenergy: I think so. Since the particle shape influences the collision behavior it should affect the resulting shapes.

[@Mehmet-uy8cr]

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.

[@johnfthiel]

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

[@fabienpaillusson7390]

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...

[@werdnativ]

@sixtysymbols, are Roger and James familiar with the work of Dr. Gerald Pollack? There's a video of him here on KZbin 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.

[@Taneth]

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.

[@MBAustin13]

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.

[@Spookyhoobster]

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?

[@DrDeeDot]

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.

[@MrOldprof]

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.

[@PetraKann]

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)

[@evildude109]

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.

[@otonanoC]

The ending is astonishing.

[@BruceCrossan]

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.

[@MrOldprof]

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

[@spilperson]

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.

[@pacogoatboy]

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.

[@PennyDorkis]

See the Brazil Nut Effect (sixtysymbols) video Brady put in the video responses above. It is very relevant to your question.

[@o0oo0ooo0oooo0ooooo0]

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.

[@Momohhhhhh]

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.

[@EzekialDantes]

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.

[@willpower8888]

Search Cymatics to see more, changing the frequency of vibration effects the pattern of distribution.

[@MrOldprof]

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.

[@GetMeThere1]

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.

[@ARiverSystem]

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.

[@mybluemars]

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!

[@TheRandomOpera]

Thanks for clarifying! :)

[@NickRoman]

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.

[@davefoc]

This reminded me a bit of the strange patterns that set up in miso soup. I'd expect randomness but for some reason the suspended solids seem to concentrate in non random patterns.

[@legatolutherie]

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?

[@mybluemars]

What frequency are you shaking the box? Did you try changing the frequencies? Thank you

[@MrOldprof]

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).

[@atrumluminarium]

It's rather unfortunate that James doesn't show up a lot on Sixty Symbols, I like how he explains stuff.

[@MrMichaelEdie]

So the regions with the highest density of particles has the lower pressure? Marvelous stuff.

[@MasterHigure]

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?

[@andrius0592]

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.

[@energysage9774]

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.

[@PseudonymousCypher]

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)

[@Octanis0]

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.

[@sinachiniforoosh]

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.

[@FPengu1n]

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?

[@mildlyacidic]

That graph is very trippy.

[@MrFarkasOfficial]

fascinating.

[@S1nwar]

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)?

[@Pianoguy32]

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.

[@spacegothgirl]

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?