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We Finally Know Why Oil and Water Don't Mix

timothy posted more than 2 years ago | from the they-split-over-demi-moore dept.

Science 222

CoveredTrax writes "Everyone knows oil and water don't mix. It's a simple concept, sure, but the hydrophobic interactions between fats and water are crucial to the mechanics of microbiology. The weird thing is, the base theories of chemistry suggest that there's no reason oil and water shouldn't mix, even though it's obvious that's not the case. Now there's an explanation: a team of chemical engineers at the University of California, Santa Barbara have defined an equation that measures a compound's hydrophobic character. It's the first such equation of its kind."

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I thought... (1)

SJHillman (1966756) | more than 2 years ago | (#37701114)

I thought it was to make me exercise more when trying to make my Amish bread every two weeks... the oil always takes extra long to mix in

Re:I thought... (3, Funny)

swanzilla (1458281) | more than 2 years ago | (#37701852)

FTA:

The model quantitatively accounts for the elastic strains, deformations, long-range forces, energy maxima, adhesion minima, as well as the instability (when it exists) as two bilayers breakthrough and (hemi)fuse. These results have several important implications, including quantitative and qualitative understanding of the hydrophobic interaction, and making Amish bread makers exercise more.

Partial credit awarded.

Huh? (2, Insightful)

Anonymous Coward | more than 2 years ago | (#37701118)

I read TFA, and I still don't know why oil and water don't mix. Frankly, I don't think these researchers do, either. They seems to have come up with some kind of empirical formula that describes the interactions without really understanding why they are happening.

Re:Huh? (1, Informative)

Anonymous Coward | more than 2 years ago | (#37701132)

you mean like newton and gravity?

Re:Huh? (0)

Anonymous Coward | more than 2 years ago | (#37701152)

No, like Newton and gravy.

Re:Huh? (1)

j00r0m4nc3r (959816) | more than 2 years ago | (#37701396)

mmm fig newtons and gravy

Re:Huh? (1)

Hatta (162192) | more than 2 years ago | (#37701154)

That's what science does. It describes the way things behave. "why" is an invention of the human mind. It's not cromulent to expect a scientific answer on "why" things happen, they just do.

Re:Huh? (2)

LordLimecat (1103839) | more than 2 years ago | (#37701184)

If science didnt believe there was a "why", it wouldnt bother with experiments in the first place. The why is what we are generally after-- what is the cause?

Re:Huh? (1)

zblack_eagle (971870) | more than 2 years ago | (#37701214)

Funny, I always thought that science was about reproducibility

Re:Huh? (1)

JustOK (667959) | more than 2 years ago | (#37701330)

sometimes it is about things that are not reproducible.

Re:Huh? (0)

Anonymous Coward | more than 2 years ago | (#37701922)

"sometimes it is about things that are not reproducible."

Kind of like most Slashdotters?

Re:Huh? (1)

Gideon Wells (1412675) | more than 2 years ago | (#37701338)

If it is reproducible then we ideally have the "why" down or can tweak till we see the variable that leads to "why". You could have "Why" in experiment 1, but you need at times up to experiment 100 to be sure that "why" is not "interesting glitch".

Re:Huh? (2)

LordLimecat (1103839) | more than 2 years ago | (#37702078)

Reproducibility implies an unchanging cause, that is, a why. If there isnt a cause to something, you will be unable to reproduce it.

Re:Huh? (0)

Anonymous Coward | more than 2 years ago | (#37702812)

No, reproducibility implies an unchanging mechanism, i.e. a how. Linguistically, "why" implies a goal or motive. It is only through the ambiguity of language that reason, cause/effect and motive have overlapping definitions.

Re:Huh? (1)

Hatta (162192) | more than 2 years ago | (#37701296)

Scientists may be out to find a why, but it only exists in their minds. "How" and "what" are all that really exist, anything more is anthropomophizing the universe.

Re:Huh? (1)

jpapon (1877296) | more than 2 years ago | (#37701606)

So you're saying causality is a creation of the human mind?

Re:Huh? (1)

LordLimecat (1103839) | more than 2 years ago | (#37702098)

You would be surprised at how many armchair scientists would declare causality to be simply a figment.

Re:Huh? (1)

digitig (1056110) | more than 2 years ago | (#37702186)

Some scientists seem to be saying something along those lines [postbiota.org] . But separating the how and the why doesn't necessarily do that. In popular usage "why" has multiple meanings. When scientists exclude "why" explanations they're just using one of those popular meanings; they're actually excluding teleological explanations, but most folks are happier with words like "why" than with words like "teleological".

Re:Huh? (1)

Darfeld (1147131) | more than 2 years ago | (#37702348)

No, he is saying there are no meaning in the fall of an apple.

Re:Huh? (3, Interesting)

rufty_tufty (888596) | more than 2 years ago | (#37701418)

Not really.
Does gravity work because mass distorts space or because of gravitons? At the heart of it most science doesn't care why, but it does care what.
Now theories are proposed to postulate a why, but they're usually used to encourage more experiments.
Many of the previous whys have been proved wrong, or at least incomplete, bohr model of the atom Newton's universal gravitation, any theory of superconductivity; but it doesn't matter the experiments and results were real and the ideas produced by the models useful.
Can't remember who said this, but Asking why we do science is like asking why we have sex, sure sometimes something useful comes out, but that's not the reason we're doing it.

Re:Huh? (2, Interesting)

Anonymous Coward | more than 2 years ago | (#37701720)

The answer to "why" something is, is that God did it. All the time. Every time.

At least according to my grandfather. An overly simplified conversation regarding such went like so:

Him: Helium rises because God did it.
Me: Helium rises because it is lighter than the rest of our atmosphere.
Him: Why is it lighter?
Me: It has less mass.
Him: Why does it have less mass?
Me: Because it does?
Him: So you admit that God did it.

Re:Huh? (4, Insightful)

maxwell demon (590494) | more than 2 years ago | (#37702268)

Well, I wonder how he would have coped with the following:

Him: Why is it lighter?
You: Because it has fewer nucleons.
Him: Why does it have fewer nucleons?
You: Because otherwise it would not be Helium.
Him: Why would it not be Helium?
You: Because we humans defined Helium that way.

Re:Huh? (1)

LordLimecat (1103839) | more than 2 years ago | (#37702132)

Does gravity work because mass distorts space or because of gravitons? At the heart of it most science doesn't care why,

Those ARE the why. Asking "why" is asking "what caused the phenomenon in question". If its because of gravitons, the gravitons are the why, the distortion is the what, and so on.

Im not sure if we have a simple failure of communication here, or if people dont understand the definition of "why", or if people are actually denying causality.

Re:Huh? (1)

rufty_tufty (888596) | more than 2 years ago | (#37702692)

I take your point, but i don't think science is that simple (it never is, but that's it's charm).

I've tried to write a point below but Feynman explained it far better than I can: http://www.youtube.com/watch?v=wMFPe-DwULM [youtube.com]

The why of Newtonian gravity is that mass attracts other mass proportional to the two masses and that attraction falls off with distance by the inverse square law.
Why it does that could be spacial distortion of relativity or it could be gravitons or it could be a new model we have yet to come up with.
TBH I believe we've already reached the state where spacial distortion is an insufficient answer to the why of Newtonian gravity because it doesn't work at the quantum level and certainly dark matter and energy seem to indicate there may be BIG errors in that model of why gravity works like it does,
My point is that the answer to the question why changes as human understanding and imagination crafts new model. It is not nore do i think it ever will be an absolute answer.
Take another example. Why does a rainbow look like it does. Because the rain drops act like a prism. But what about the shape of it? Why can you only see it when the sun is behind you. There is never a simple or full answer to any why question, and the answer to that question also needs to change with your audience.
Why when my finger touches a key on the keyboard does the key get pushed down? Well i could talk about the electrostatic fields of the atoms as they interact with each other and why they become so strong over small distances to make matter feel solid when in fact it is just electromagnetic fields interacting. None of that though explains why the electrostatic fields around atoms behave as they do. Sure we have equations that describe all these interactions and to get back to the article that is the important point. We have equations for all the things discussed here, from electromagnetism to dynamics of a rainbow to gravity etc. But there really is no good answer to why any of these things.

See Feynman did say it much much better than me

Re:Huh? (4, Insightful)

Kjella (173770) | more than 2 years ago | (#37701842)

Well there's two meanings:
Q: Why does the apple fall to the ground?
A: Gravity

Q: Yes, you've named the force and given me a formula to calculate it but why does the apple fall to the ground?
A: We don't know, and even if we ever find something more fundamental that explains gravity, then that again won't have a "why".

Science explains the "how", when you derive it from other things we often say "why". But if you want turtles all the way down, there's no "why", no reason the universe is this way and not some other way. It's purely descriptive of the way it is.

Re:Huh? (1)

Hatta (162192) | more than 2 years ago | (#37702072)

Thanks! That's a really clear way of getting across what I was trying to say.

Re:Huh? (1)

LordLimecat (1103839) | more than 2 years ago | (#37702148)

Q: Yes, you've named the force and given me a formula to calculate it but why does the apple fall to the ground?
A: We don't know, and even if we ever find something more fundamental that explains gravity, then that again won't have a "why".

Which is how science works, and what it is all about. If we had no desire to climb further up the chain in causality, we would never do experiments.

Re:Huh? (1)

ShakaUVM (157947) | more than 2 years ago | (#37702668)

Science deals with How stuff works, not Why stuff works. Ten million books on "Why does fire burn?" notwithstanding.

Why just takes you one level down, and will eventually reach a level called "I dunno, the universe just works that way."

Re:Huh? (2)

MokuMokuRyoushi (1701196) | more than 2 years ago | (#37701334)

"Just because" is not an excuse I've ever heard a scientist use. In any case, I think OP actually has something; the discovery is a measurement of what's happening, not an explanation. It seems they still don't know why fat and polar compounds interact the way they do, and in fact are still baffled, because they see no reason for them not to interact normally rather than repel each other. However, we can now measure to what degree it occurs. Anybody want to correct me or clarify? I'm actually pretty interested here.

Re:Huh? (1)

maxwell demon (590494) | more than 2 years ago | (#37701610)

Actually we have microscopical theories which are assumed to describe everything (well, everything relevant at that level, at least). Therefore an understanding would mean to derive the formula from those theories (just as we understand why the earth goes around the sun by solving the equation of motion in a gravitational field). We did not fully understand Mercury's movement before Einsteins GR, because we could not completely describe its movement with the existing theories.

An explanation of why oil and water don't mix would mean to derive that formula from the fundamental laws of physics (in this case electrodynamics and quantum mechanics).

Re:Huh? (1)

Hatta (162192) | more than 2 years ago | (#37701886)

Therefore an understanding would mean to derive the formula from those theories (just as we understand why the earth goes around the sun by solving the equation of motion in a gravitational field).

Solving the equation for motion in a gravitational field tells you what happens, not why.

Re:Huh? (1)

maxwell demon (590494) | more than 2 years ago | (#37702152)

Therefore an understanding would mean to derive the formula from those theories (just as we understand why the earth goes around the sun by solving the equation of motion in a gravitational field).

Solving the equation for motion in a gravitational field tells you what happens, not why.

No, solving the equation of motion tells you why it happens, by identifying the conditions which are relevant for it happening (the equations for example tell you that if the earth would be much faster, it wouldn't go round the sun but fly away).

Re:Huh? (1)

nomadic (141991) | more than 2 years ago | (#37702372)

Have to add my disagreement here; science is all about the why. In ecology and biology textbooks you'll sometimes see equations like this ("this formula is based on empirical observation") but the authors are typically very careful about distinguishing it from the rest of what they present, and usually describe it in an embarassing tone ("we really wish we knew why this formula works, but for the present moment all we do know is it does").

Re:Huh? (1)

SleazyRidr (1563649) | more than 2 years ago | (#37702814)

I actually thought they did mix. I remember a story a few years ago that said the only reason the wouldn't mix was because of impurities, so ultra-pure oil would mix with ultra-pure water. They had ideas about environmentally-friendly cleaning products.

Entropy (5, Informative)

vossman77 (300689) | more than 2 years ago | (#37701170)

As I teach in my biochemistry class it is entropic cost of not separating them that causes their separation, but I have yet to really wrap my head around this study. Nonetheless, here are some links to the original research:

* Abstract: http://www.ncbi.nlm.nih.gov/pubmed/21896718 [nih.gov]
* PNAS (paywalled): http://www.pnas.org/content/108/38/15699 [pnas.org]

Re:Entropy (0)

Anonymous Coward | more than 2 years ago | (#37701952)

Thanks for the links.

Re:Entropy (5, Interesting)

digitalderbs (718388) | more than 2 years ago | (#37702762)

I'd like to add a few points to this useful post, as a related expert.

As implied by the parent post, one of the biggest reason scientists care is because this is a dominating contribution to the folding of soluble proteins--proteins in water. The hydrophic effect has been understood for a long time (half a centery), including the fact that the entropic contribution to the free energy is proportional to the surface area change between two separate oil droplets and one. (This is the a-a(0) term in their equation.)

Their equation further adds contributions for the surface tension of the solvent (gamma) and an exponential decay term for the drying of water between the two two hydrophobic surfaces are they approach each other. Such phenomena have been well characterized in the last ten or so years by molecular dynamics simulations, and this appears to be an experimental confirmation of this effect.

The statement, however, that this paper finally describes the enigmatic hydrophobic effect is a gross PR overstatement.

Re:Entropy (1)

spads (1095039) | more than 2 years ago | (#37702886)

I'm not sure about the equation, but I don't like how the article is worded.

It is true that an isolated oil molecule would form van der Waals interactions with water, however those interactions are more energetically favorable with other oil molecules. It has to do with minimizing the surface free energy (ie. unsatisfied association interactions) of the system. There is less unsatisfied association interaction for oil molec + oil molec vs oil molec + H2O.

This seems like bs:

"Yet as high school chem students learn, the set of weak intermolecular forces call van der Waal forces suggest that there’s no reason for the compounds not to attract each other."

Fatties have rabies. News at 11 (0, Troll)

Culture20 (968837) | more than 2 years ago | (#37701188)

Fat is hydrophobic, ergo fat people have hydrophobia aka rabies.

Re:Fatties have rabies. News at 11 (-1)

Anonymous Coward | more than 2 years ago | (#37701222)

But do they blend?

Really... (0)

Anonymous Coward | more than 2 years ago | (#37701212)

If they could just solve the why water is wet we'd be good to go...

I read TFA (3, Insightful)

bryan1945 (301828) | more than 2 years ago | (#37701226)

And basically it says van der Waals' theory is wrong, and here is a new equation. That's pretty much it.
Anyone who knows about this stuff want to take a look at the equation, and see if it makes any sense? Not my area.

E(D)= -2i(a-a)e^(D-D)
where:
E = energy
D = distance
a = area of molecule

Re:I read TFA (1)

bryan1945 (301828) | more than 2 years ago | (#37701258)

Oops
  -2y[sub i](a-a[sub 0])e^(D-D[sub 0])
Forgot /. doesn't like weird characters.

Did you? (1)

mrtumnus (1793406) | more than 2 years ago | (#37701648)

That would be E(D) = -2y[sub i](a-a[sub 0])e^(-D/D[sub 0])

Re:I read TFA (0)

Anonymous Coward | more than 2 years ago | (#37702122)

It would make sense if they used gamma instead of y. I'm dumbfounded and will have to think more about the implications. Thanks for sharing!

Re:I read TFA (1)

TreeInMyCube (1789238) | more than 2 years ago | (#37702428)

A quick assessment ... the hydrophobic ("water-fearing") nature scales linearly with the areas of the molecules, and follows an exponential distribution with the distance between them. The exponential part is similar to the Boltzmann expressions that are used to describe the kinetic motion of the molecules, and they are derived from kinetic theory that treats the molecules like billiard balls. There's a characteristic distance [D sub 0] which represents the size of the organic molecule, and an adjustable coefficient [gamma sub i] that can be adjusted for different substances. Looks legit ...

Re:I read TFA (0)

Anonymous Coward | more than 2 years ago | (#37702590)

1. This is supposedly empirical formula - it offers no insight.
2. I see no explanation what that (i) stands for (gamma_i in original)

Others have supposedly mixed oil and water,

http://www.newscientist.com/article/dn3408-oil-and-water-do-mix-after-all.html [newscientist.com]

Leave it to UCSB (1)

Anonymous Coward | more than 2 years ago | (#37701254)

To research the dynamic of Salad Dressing. And im posting this sitting at work not half a mile from there.

And here I thought (1)

tmosley (996283) | more than 2 years ago | (#37701266)

And here I thought it was because they are more attracted to each other than they are to other types of compounds, ie water strongly hydrogen bonds to itself, squeezing out any hydrophobic molecules, while long hydrophobic chains stack strongly, squeezing out anything that doesn't stack strongly.

Re:And here I thought (0)

Anonymous Coward | more than 2 years ago | (#37701636)

Cool. Looks like you thought wrong!

Re:And here I thought (2)

TeknoHog (164938) | more than 2 years ago | (#37701702)

I thought this too. Another practical reason is that the two liquids usually have different densities, so one will tend to float on top of the other.

I'm not sure about the stacking theory though. Long-chain molecules are not exactly straight, at least when in the liquid phase. If they were to stack neatly with each other, you would get a crystal. My impression is that polar interactions are generally stronger, so it is mainly water that squeezes out any non-polar intruders.

Re:And here I thought (1)

Arrepiadd (688829) | more than 2 years ago | (#37701780)

Another practical reason is that the two liquids usually have different densities, so one will tend to float on top of the other.

You mean like alcohol and water? Or like typical gases dissolved in water?
The "one floating on top of the other" is a consequence of them not being miscible, not the other way around.

Re:And here I thought (1)

digitig (1056110) | more than 2 years ago | (#37702198)

I thought it was because one ran Linux and the other ran MS Windows.

My understanding (0)

Anonymous Coward | more than 2 years ago | (#37701280)

In high-school chem, I was taught that water molecules stick together because they are shaped like mickey-mouse heads. (The positive ears are attracted to the negative face, so they all chain together.) Oil is shaped in a straight line, with the same charge on each end, so it has no such effect. When water sticks together, it pushes the oil out, like how popular kids push the anti-social geeks out of their circles, even if they don't explicitly hate the geeks. So, did my chem teacher just make that up? Is it completely wrong?

Re:My understanding (1)

Iniamyen (2440798) | more than 2 years ago | (#37701540)

This is what I was taught as well. So I don't really understand what they've done, except create some derived value that may be useful, but doesn't "explain" anything new. And it took them 30+ years.

As Bill O'Reilly would say. (0)

Anonymous Coward | more than 2 years ago | (#37701320)

Oil and water don't mix, you can't explain that... Oh, wait. My God's bubble of science ignorance just got smaller again.

Re:As Bill O'Reilly would say. (0, Insightful)

Anonymous Coward | more than 2 years ago | (#37701646)

It still amazes me when I meet atheists who hang their hat on science. Science is extremely valuable, however it's the least tenable theological position.

Re:As Bill O'Reilly would say. (0)

Anonymous Coward | more than 2 years ago | (#37701742)

It's funny when you use words that you don't understand.

Re:As Bill O'Reilly would say. (0)

Anonymous Coward | more than 2 years ago | (#37701920)

Mod parent up.

Re:As Bill O'Reilly would say. (1)

Abstrackt (609015) | more than 2 years ago | (#37702402)

I would argue that no theological position, atheist or otherwise, is tenable. Everyone believes in something but the only conclusive proof we get is when we die, at which point it becomes extremely difficult to say "ha, I told you so!".

Oil and degassed water mix fine. (0)

Anonymous Coward | more than 2 years ago | (#37701382)

See http://www.newscientist.com/article/dn3408-oil-and-water-do-mix-after-all.html .

I assume the new theory / equation actually works with both the water and gas molecules in consideration, although in TFA I saw no mention of it.

I thought the reasons whre obvious? (1)

angel'o'sphere (80593) | more than 2 years ago | (#37701400)

If you carefully put oil on top of water, you realize it "swims" as it is lighter than water.

Now if you shake it, your might expect it could "mix" with water, like alcohol e.g. does.

Now you have to understand that there are different kinds of "mixes".

Alcohol in water is a kind of solution, like salt in water (albeit looking closer at it, there is a significant difference).

However, oil in fact does mix with water pretty fine if you can make the oil into very small droplets.

Milk e.g. is an emulsion of water an oil (amoung other parts), an ordinary skin cream e.g. is a mixture of oil and water.

The main reaon why oil and water don't want to mix without help is simple: surface tension of water, and the chain building of water molecules. Water molecules are di-poles. They have a + charged and and a - charged end. Like magnets they build long chains of water molecules. That means instead of staying arbitrary close to an oil molecule they turn away from the oil and look for another water molecule. Most oils/fats have no poles.

Bottom line molecules that are bi-polar and those that are mono-polar don't mix good (or not at all).

Anyway that is school knowledge, and yes I have read the posted article ...

Re:I thought the reasons whre obvious? (3, Informative)

cmacdonald (2484050) | more than 2 years ago | (#37701726)

Right, but try and use those sentences to predict and calculate the magnitude of those forces. How is that going? The reason this seems to be significant is it allows us to model these forces beyond the the explanation of "the oil sticks together". Van der waals forces don't apply accurately here so we don't have a good tool to calculate these things. From the actual publication: "A quantitative and general model is derived for the interaction potential of charged bilayers that includes the electrostatic double-layer force of the Derjaguin-Landau-Verwey-Overbeek theory, attractive hydrophobic interactions, and repulsive steric-hydration forces. The model quantitatively accounts for the elastic strains, deformations, long-range forces, energy maxima, adhesion minima, as well as the instability (when it exists) as two bilayers breakthrough and (hemi)fuse. These results have several important implications, including quantitative and qualitative understanding of the hydrophobic interaction, which is furthermore shown to be a nonadditive interaction." While I wouldn't want to imply it's on the following scale, it's along the lines of the difference between "gravity pulls us down towards the earth" and Newton's Law of Universal Gravitation. Long time listener, first time poster. I apologize for not being able to make new lines somehow.

Don't mix good? (0)

Anonymous Coward | more than 2 years ago | (#37702308)

Grammer Nazis to the rescue!

But why does emulsifying cause them to mix (1)

sirwired (27582) | more than 2 years ago | (#37702658)

Just being pedantic, but homogenized milk is an emulsion; milk out of the cow most certainly separates into milk and buttercream (and the buttercream itself is a high-fat emulsion; it still has a lot of moisture in it.)

If you could explain it away with polar bonds (or lack thereof), why do emulsions emulsify? The hydrocarbon and water molecules have the same number of bonds, and the same density, no matter how vigorously you shake them.

Amazing, what we still don't know... (1)

taiwanjohn (103839) | more than 2 years ago | (#37701408)

I have no background in this area, but I'm surprised to learn that we didn't know this already. Makes you wonder what other "simple" discoveries are waiting in around the corner.

Re:Amazing, what we still don't know... (-1)

Anonymous Coward | more than 2 years ago | (#37701930)

And yet we are not allowed to question manmade climate change.

Oh yes, we know EVERYTHING. But we don't.

Re:Amazing, what we still don't know... (1)

taiwanjohn (103839) | more than 2 years ago | (#37702106)

At this point, I don't think it matters much. The damage is already done, we're just going to have to deal with it someday. In the meantime, the rising cost of oil has made alternatives more economical, driving faster uptake. So eventually the problem will solve itself. I just hope a "mass extinction" of Homo sapiens is not a part of that solution.

Polarity? (0)

Anonymous Coward | more than 2 years ago | (#37701420)

I'm only remembering from High School Science, so I'm sure I'm wrong, but I thought it was as simple as polar/non-polar solvents. Since water is polar, it won't accept a nonpolar (i.e. oil) solute. Or is this just a paper about a new equation describing that relationship?

Yeah right! (0)

Anonymous Coward | more than 2 years ago | (#37701430)

On July 31, 2009, Sterling D. Allan interviewed Paul Pantone, at the Nativo Lodge in Albuquerque, New Mexico, USA, as part of the ExtraOrdinary Technology conference. Progress report on the GEET Plasma Reactor which uses the engine exhaust flowing in one direction to heat up incoming fuel flowing in the opposite direction, around a rod of a specific length, per the type of fuel, to create a plasma gas which then performs in a very unusual way in the engine to profoundly increase the mileage of the vehicle and reduce emissions. It also enables the vehicle to run on a wide variety of fuels, including water, inasmuch as the plasma-created gas is the operating substance. ([http://www.youtube.com/watch?v=pbo80DbZHqk YouTube; Aug. 1, 2009)

source: http://peswiki.com/index.php/Directory:GEET_Reactor_by_Paul_Pantone

so while some make engine mixing oil and water some say it's impossible. Go figure!

Terrible title and summary (0)

Anonymous Coward | more than 2 years ago | (#37701434)

The paper's authors haven't "explained" anything. They've devised a formula that does an acceptable job of matching empirical data. This isn't the same thing as "understanding" how the underlying competing physical processes give rise to the observed behavior of oi/water.

Re:Terrible title and summary (1)

spikenerd (642677) | more than 2 years ago | (#37702422)

How would you propose to "understand" a natural phenomenon better than building a model that explains empirical observations? I argue that building a model that can make accurate predictions is the very definition of understanding something.

Re:Terrible title and summary (1)

HornWumpus (783565) | more than 2 years ago | (#37702866)

Build a good model.

From upthread: There's a characteristic distance [D sub 0] which represents the size of the organic molecule, and an adjustable coefficient [gamma sub i] that can be adjusted for different substances.

Sounds more like a fit then a model. It even has 'finaglers constant' (gamma sub i).

More than just microbiology (1)

sootman (158191) | more than 2 years ago | (#37701440)

> the hydrophobic interactions between fats and water
> are crucial to the mechanics of microbiology

Also, salad dressing.

Re:More than just microbiology (1)

idontgno (624372) | more than 2 years ago | (#37701562)

I am reassured that although we now understand better the molecular interactions between top-grade extra virgin olive oil and an extravecchio balsamic vinegar, the mysteries of the delightful concoction created by forcibly mixing the two are still untouched.

Explain a good salad dressing down to the quantum level, and it will still be good beyond human comprehension.

Ig Nobel (1)

ChikMag777 (1337235) | more than 2 years ago | (#37701450)

I thought the winners of the 2010 Ig Nobel Chemistry prize disproved the old belief that oil and water don't mix. http://improbable.com/ig/winners/#ig2010 [improbable.com]

I wonder... (1)

sootman (158191) | more than 2 years ago | (#37701502)

... what would the gulf oil spill have been like if oil and water did mix?

Re:I wonder... (1)

Anonymous Coward | more than 2 years ago | (#37701608)

... what would the gulf oil spill have been like if oil and water did mix?

It would have been similar to a shark and a bear putting aside their ancient enmity and teaming up... to fight crime!

Re:I wonder... (1)

jfengel (409917) | more than 2 years ago | (#37701612)

Like dark gray mayonnaise.

Re:I wonder... (1)

gewalker (57809) | more than 2 years ago | (#37701714)

Exxon would have saved a lot of money buying and applying oil-dispersing chemicals (pretty much Dawn detergent with additives). This was a major means of responding to the spill. Beach cleanup would not be much of a problem, etc. -- Would be better environmentally in just about every way.

It would have been no big deal (1)

sirwired (27582) | more than 2 years ago | (#37702686)

If oil and water DID mix, the total volume of oil, which would have dispersed over the massive body of water that is the Gulf of Mexico, would have been a rounding error. There would have been some localized effects, but not catastrophic ones in any way.

how is baby formed (0)

Anonymous Coward | more than 2 years ago | (#37701558)

OH FFS

A measure of particular phobic character does not explain why the membranes materialize.

Re:how is baby formed (4, Funny)

Reverand Dave (1959652) | more than 2 years ago | (#37701782)

Hey, if you're not part of the solution, you're part of the precipitate.

yeah, well, actually, they do mix. (2)

cellocgw (617879) | more than 2 years ago | (#37701578)

Old news -- maybe you youngsters can't remember:

yes they do [newscientist.com]

Re:yeah, well, actually, they do mix. (0)

Anonymous Coward | more than 2 years ago | (#37702138)

If you read TFA and your article, you would see that they aren't in opposition with each other.

Your linked article states even though they may have caused oil to mix with water, it did not solve the hydrophobic forces (only that dissolved gasses seems to play a role). TFA states the chemical engineers in question state they solved the hydrophobic forces.

Blackboards Again!!!!! (0)

guitardood (934630) | more than 2 years ago | (#37701716)

The OP said in his subject that now we KNOW why. No we don't!!!! We just have a couple of overpaid math geeks coming up with some algebraic gibberish that they hope nobody else will understand enough to question them. Aren't there any real scientists on this planet besides the great folks at JPL? Meaningless equations based on unfounded theories ARE NOT FREAKIN FACTS!!!!!!!!! And to the person who explained science's job as answering 'why', you are correct. However, the 'why' can't be "Because some fairies sprinkled magic dust on the oil and thats what makes it repel water". Just giving a made up answer is NOT answering the 'why'. It's no wonder this planet is going to hell on a short yellow bus. Sorry for the rant, haven't had my coffee yet today.

Re:Blackboards Again!!!!! (0)

Anonymous Coward | more than 2 years ago | (#37701850)

amen

Re:Blackboards Again!!!!! (0)

Anonymous Coward | more than 2 years ago | (#37701918)

I've got a feeling you're not a scientist nor are you involved in the scientific process.

Re:Blackboards Again!!!!! (1)

guitardood (934630) | more than 2 years ago | (#37701962)

Actually, I was in gifted algebra and physics classes in 7th grade circa 1977. And I'm sure if Mr. Jaloweic(sp?) were able to hear this nonsense his coffin would be drilling to China about now.

Re:Blackboards Again!!!!! (1)

ErikZ (55491) | more than 2 years ago | (#37702014)

Math is the language used to describe the physical interactions of the universe.

They think they've come up with something that will accurately describe the physical phenomena of oil and water interaction. This will examined by people who are doing work in relevant studies.

If you want an explanation of *why* they act like this, go find someone who's job involves working with this phenomena and he/she will probably be happy to talk about it.

Um, UNIQUAC? Yes. (0)

Anonymous Coward | more than 2 years ago | (#37702038)

As far as I remember, UNIQUAC is a model that can predict VLE/LLE/VLLE/whatever equilibrias by looking at the character of molecules (if it has a ketone or caboxylic acid, it will have a different character than one that is a straight chain).

And if I remember right, it does predict that oil and water will not, in fact, be in the same phase since it would then be an LLE.

However, one should always note that even though there are two phases, small amounts of water are found in the oil phase and vice versa.

first such equation which measures? (1)

smoothnorman (1670542) | more than 2 years ago | (#37702064)

a team of chemical engineers at the University of California, Santa Barbara have defined an equation that measures a compound's hydrophobic character. It's the first such equation of its kind.

Perhaps there's an escape via language lawyerism via "of its kind" but for decades there has been software to estimate the hydrophobicity of small molecules and (relying on even more approximations) proteins. Underlying that software are scores of "equations" that use tables of atomic and molecular fragment parameters of electronegativity and polarizability to calculate 'not bad' estimates of molecular hydrophobicity.

And while i'll quibble about "the first such equation"; i really think most folks should quibble over "defined an equation that measures", people armed with instruments "measure", equations 'calculate an estimate'. ok, now: hey you kids get off my lawn!

Re:first such equation which measures? (1)

Orsmo (976) | more than 2 years ago | (#37702400)

Even more correctly, an equation "describes". The accuracy of the description provided by the equation relative to measure, may merely be an estimate, or may be perfect. They may describe the limits within which values must fall, or the values themselves. Measurements themselves are after all, only estimates withing a certain degree of precision. Playing semantics isn't really the point though. What you have here is a theory that accurately predicts and explains the behavior with an accompanying equation that describes how the variables contribute said same behavior.

Shoddy headline (0)

Anonymous Coward | more than 2 years ago | (#37702288)

This is a really shoddy headline and article, and should never have made it to slashdot's front page.

The non-mixing of oil and water is well understood and has been for many years. You can easily find the explanation in a first year chemistry undergrad textbook.

The equation provided doesn't in fact offer an explanation and is just an empirical fit to some observed data. Without reading the paper it's hard to know what it's getting at but just from inspecting the equation it certainly isn't anything profound. For example, where is the information on the atoms constituting the molecules? (Probably in the gamma which may be surface tension, but that there's no way you can get the subtleties of hydrophobic behaviour in a single value like that.)

BVO (0)

Anonymous Coward | more than 2 years ago | (#37702486)

They don't mix because there's not enough bromintation!

Let me take a crack at this... (5, Informative)

snoop.daub (1093313) | more than 2 years ago | (#37702726)

I work in the field on the theory/simulation side, and have actually had dinner and discussed research with Dr. Israelachvili a couple of times. I've only had a chance to skim the paper, but I think I can summarize it pretty well... by the time I've really absorbed it you folks will have moved on to the next shiny new story so I'd better do it now!

First of all, the report claims that the paper is all about how oil and water don't mix and makes a big deal about how we don't know how that works. For simple stuff like say water and a basic hydrocarbon like octane, that's really not true... it's all about what has already been said above, polar vs. nonpolar (electrostatics) and entropy.

Things get more complicated when you want to model something like an extended hydrophobic surface, or the interactions and formation of bilayer membranes like we have in a cell. It's been known from experiments since Dr. Israelachvili's work in the 80's that if you take two such surfaces (usually mica functionalized to make it hydrophobic) and bring them together in water, they will repel each other, up until at some point they very quickly strongly attract, expel the water between them and glue themselves together (also called "cavitation"). This is the sort of data shown in Fig. 2 in the paper. The connection with membrane formation is to describe how two membranes behave when they come close together, they have to do something similar to get close enough to fuse (figure 3).

Figuring out how to describe this behaviour from a theoretical standpoint has been very difficult! We know what all the parts have to be (hydrophobic,electrostatic, steric/Van der Waals, entropic) but haven't been able to put them together in the right way to describe all of the experimental data. What Jacob and his team have done here is found a nice way to 1) describe the hydrophobic interaction between extended surfaces mathematically (the equation above), 2) combine it with all the other parts (figure 4), and 3) show that the equation with a combination of fitted and measured parameters can fit the experimental data pretty well (Table 1). It's very nice work, definitely a step forward in our knowledge of hydrophobic surface and membrane interactions, and I'm going to make sure I study it more carefully soon!

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