A well-known effect in breakfast cereal helps physicists understand the universe

Sep 09, 2010 By Eric Betz, ISNS
A bowl of cereal and milk. Credit: Conrad.Irwin

Have you ever noticed how the last bits of cereal in the bowl always seem to cling to one another, making it easy to spoon up the remaining stragglers? Physicists have -- and they've given it a name: the "Cheerios effect".

But this effect isn't exclusive to breakfast . It also reveals itself in the way particles move in the air, pollen floats on the surface of water and galaxies cluster throughout the universe.

"If you put Cheerios in a bowl, they aggregate," said Arshad Kudrolli, a physicist at Clark University in Worcester, Mass. "Or if you look at foam floating on a beer, you get clumps. That's because of surface tension."

Molecules in a fluid have a mutual attraction for each other and the effect creates surface tension -- a naturally resistant force that repels back against anything that pushes on the surface. It's that allows some insects, such as water striders, to walk across the water's surface -- and also fuels party tricks like floating paperclips or thumb tacks.

Kudrolli and colleague Michael Berhanu, also a physicist at Clark University, wanted to explore this effect in order to better understand similar phenomena in the natural world. So instead of going to the grocery store, they placed floating glass spheres in a funnel-shaped container of water. By altering the amount of water in the container, they could cause the glass spheres to either concentrate or disperse, simulating the various stages of the Cheerios effect.

"Physicists are interested in the Cheerios effect for a range of reasons," said postdoctoral researcher Dominic Vella from the University of Cambridge in the U.K., who was not involved in this research. "There are many instances of such systems in nature, so the insights that we gain from this model laboratory system may aid our qualitative understanding of more complicated systems."

Floating objects change the shape of a liquid's surface. If the molecules in an object are attracted to water, they are considered hydrophilic, or water-loving. Water gathers around the sides of the floating object and there will be a small depression beneath it called a meniscus. If the molecules in an object do not bond well with water, physicists say they are hydrophobic, or water-resistant, and the effect will create a small protruding bump underneath them -- a meniscus curved in the opposite direction.

In the case of your breakfast cereal, the Cheerios can be considered milk-philic because the O's create a small depression in the milk's surface, forcing them to fall in towards each other. Liquids can form similar features along the edges of a container and make the milk in your cereal bowl curve very slightly upward against the wall. Because Cheerios float, they will move up the curved surface of the milk and cause the O's to clump against the edges of the bowl as well.

"The bowl is also milk-philic so the meniscus goes up near it," said Vella. "This means that there is both an attraction between individual Cheerios and between a single Cheerio and the wall of the bowl."

Kusrolli and Berhanu found that when you throw just a handful of Cheerios into a bowl of milk they aggregate into hexagonal groups, but when you have many particles dispersed over a larger area -- such as pollen floating across a lake -- the particles gather into condensed areas with large gaps of empty space between the groups. While the driving force is different, Berhanu said this same effect can also be seen in the cosmos. Large clusters of galaxies and stars cling closely to each other while leaving vast amounts of empty space between them.

"If you look at the distributions of stars and galaxies, it's not random," said Kudrolli. "There are regions that are less dense, and there are regions that are more dense."

Explore further: Do we live in a 2-D hologram? New Fermilab experiment will test the nature of the universe

Source: Inside Science News Service

3.6 /5 (28 votes)

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DaveGee
5 / 5 (1) Sep 09, 2010
All they needed to do was get happy and watch an old George Carlin (RIP) stage act... And it's NOT the 'Cheerios Effect' it's the RICE CRISPY effect!

" Yes, there is a little science in the show each and every evening. But those Rice Krispies will float forever-well, you know what they do? [b]They gather together. They gather together in little groups. Little groups of eight, ten, twelve, sometimes fourteen, but always an even number. Little colonies of Rice Krispies[/b]. But you can't sink 'em. You try to sink 'em with a spoon, they come up over the side. That's what the fruit is for. Sinking the Rice Krispies. A good size peach will take down eighty or ninety of 'em every time. If I'm really pissed, I'll drop a watermelon on 'em!"
_nigmatic10
4.3 / 5 (3) Sep 09, 2010
what bowl of cereal is this? My last few never cling together and i spend a good portion of time trying to get them on the spoon before giving up and sucking the whole thing down, milk and all.
Hesperos
Sep 10, 2010
This comment has been removed by a moderator.
Pyle
4.8 / 5 (5) Sep 10, 2010
Wow! Rebranding - the key to bringing new young minds to physics. Move aside surface tension and gravity, hello "Cheerio Effect!"
Are they kidding? What's next? Newton's third law will be called the "Home Run Effect?" Static electricity can be "Socks on the Carpet Effect"? Wait. Maybe we can charge General Mills and MLB advertising fees?

Ridiculous. This one gets a 1 from me Physorg.
kevinrtrs
1.5 / 5 (6) Sep 10, 2010
Isn't there some copyright in the word Cheerios?

I think they might find themselves facing the down the wrong end of a high powered lawsuit.

And on top of it, what ever happened to the inflationary model which is supposed to have smoothed out things exactly such that no clumping can occur? And just where did the homogeneity of the Copernican principle disappear to that we now have clusters of galaxies such that things don't look the same everywhere you look?

frajo
3 / 5 (4) Sep 10, 2010
If the molecules in an object are attracted to water, they are considered hydrophilic, or water-loving. Water gathers around the sides of the floating object and there will be a small depression beneath it called a meniscus. If the molecules in an object do not bond well with water, physicists say they are hydrophobic, or water-resistant, and the effect will create a small protruding bump underneath them -- a meniscus curved in the opposite direction.
It's the other way round.
Everybody who's ever seen an insect walking on water has seen the circular depressed water surface around the insect's feet. (If not, see http://en.wikiped...Gerridae ) The feet are hydrophobic; otherwise the insect would drown.
"The bowl is also milk-philic so the meniscus goes up near it,"
Now they got it right. Except their language - it's "galaphilic".
ShotmanMaslo
5 / 5 (1) Sep 10, 2010
Isn't there some copyright in the word Cheerios?

I think they might find themselves facing the down the wrong end of a high powered lawsuit.

And on top of it, what ever happened to the inflationary model which is supposed to have smoothed out things exactly such that no clumping can occur? And just where did the homogeneity of the Copernican principle disappear to that we now have clusters of galaxies such that things don't look the same everywhere you look?



Things are smooth and homogenic, but on the scale of cca 500 million light years. This article talks about much smaler scales, where no isotropy is expected.
hodzaa
1.7 / 5 (6) Sep 10, 2010
..Move aside surface tension and gravity, hello "Cheerio Effect!".... This one gets a 1 from me Physorg.
Actually, I would be banned for PSEUDOSCIENCE, if I would call gravity a surface tension force or "Cheerio Effect" just before six months here. After all, the article above doesn't explain this analogy anyway and you can read nothing about it even in original publications - it's completely the private invention of the authors.
hodzaa
1.6 / 5 (7) Sep 10, 2010
..and just where did the homogeneity of the Copernican principle disappear to that we now have clusters of galaxies such that things don't look the same everywhere you look?
The cosmologists have theories for both homogeneity, both inhomogeneity of universe, which they're alternating by context - after all why not, if you're paying it from your taxes freely.
Skeptic_Heretic
3.4 / 5 (5) Sep 10, 2010
And on top of it, what ever happened to the inflationary model which is supposed to have smoothed out things exactly such that no clumping can occur? And just where did the homogeneity of the Copernican principle disappear to that we now have clusters of galaxies such that things don't look the same everywhere you look?

You're mistating two well understood theoretical frameworks. Very ignorant of you, again kevin.

You don't really believe the foolishness you spew on these pages, do you? I'd have a hard time looking at myself in the mirror if I was as willfully ignorant as you seem to be.
hodzaa
1.7 / 5 (7) Sep 10, 2010
Very ignorant of you, again kevin.
Why do you mean? Both Copernican principle, both inflation were proposed to explain homogeneity of Universe. BTW your post contains only logical fallacies and ad-hominem attack. Absolutely no arguments, which could explain your negativistic stance, to support it with some logics the less. It's uselless spiteful spam, could be said.
Skeptic_Heretic
3.4 / 5 (5) Sep 10, 2010
Why do you mean? Both Copernican principle, both inflation were proposed to explain homogeneity of Universe.
Neither was posited to explain homogenity. Both were posited to explain the distribution of baryonic matter. This is common knowledge for jsut about anyone who claims to know even a touch of cosmology.
BTW your post contains only logical fallacies and ad-hominem attack. Absolutely no arguments, which could explain your negativistic stance, to support it with some logics the less. It's uselless spiteful spam, could be said.
Like you, he refuses to learn. We've had this conversation, he and I, several times now. I have no need to re-tread barren ground over and over and over.

I do it with you because from time to time you actually do learn something and change your stance. Even though you'll never admit to it.
Jimbaloid
4.5 / 5 (2) Sep 10, 2010
I guess Cheerios are more appealing to physicists because of their toroidal shape?
Sirinx
1.7 / 5 (6) Sep 10, 2010
I guess Cheerios are more appealing to physicists because of their toroidal shape?
Probably yes.
.Neither was posited to explain homogenity. Both were posited to explain the distribution of baryonic matter...
..a HOMOGENEOUS distribution of baryonic matter..

http://nedwww.ipa...den.html

"Inflationary models provide a potential explanation of the flatness of the universe and of its homogeneity on large scales. "

This is common knowledge for just about anyone who claims to know even a touch of cosmology.
Skeptic_Heretic
3 / 5 (2) Sep 10, 2010
..a HOMOGENEOUS distribution of baryonic matter..
Wrong.

A homogenous distribution based on the CMB, not within observation of baryonic matter. Your own source says as much as well.

This is common knowledge for just about anyone who claims to know even a touch of cosmology.

But for it to be recognizable as such it must be expressed properly, and not with a half baked and poorly understood definition of the concepts.

Keep trying to play the game, you show that you know less and less with each post.
CouchP
not rated yet Sep 10, 2010
what bowl of cereal is this? My last few never cling together and i spend a good portion of time trying to get them on the spoon before giving up and sucking the whole thing down, milk and all.


when they are getting soggy the meniscus is removed thus the effect is lost.
AWT
1 / 5 (3) Sep 12, 2010
Neither the original article, neither the effect studied provides at least a bit of theoretical or experimental evidence of connection of stellar clustering with aggregation of small disks at the water surface.