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## Mathematicians Show Why Bubbles Sink in Nitrogen-Infused Stouts55

SicariusMan writes "The age old question: do Guinness and other stouts' bubbles really sink, or is it an optical illusion? Well, some mathematicians have figured it out." Full paper via arXiv; From the article: "To analyze the effect of different glass shapes, the mathematicians modeled Guinness beer containing randomly distributed bubbles in both a pint glass and an anti-pint glass (i.e., an upside-down pint). An elongated swirling vortex forms in both glasses, but in the anti-pint glass the vortex rotates in the opposite direction, causing an upward flow of fluid and bubbles near the wall of the glass."
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## Mathematicians Show Why Bubbles Sink in Nitrogen-Infused Stouts

• #### Now that I know the theory (Score:5, Funny)

on Wednesday May 30, 2012 @12:28PM (#40157267)
Allow me to practice ...
• #### late to the party (Score:5, Informative)

by Anonymous Coward on Wednesday May 30, 2012 @12:33PM (#40157313)

The Australians figured it out 12 years ago

http://science.slashdot.org/story/00/01/11/2156213/why-bubbles-in-guinness-fall

• #### And no wonder (Score:1)

by Anonymous Coward

Australians do not like any confusion or doubt when it comes to beer. Mind you, apparently they initially thought it happened because Guiness comes from the North.

• #### Re:late to the party (Score:5, Funny)

on Wednesday May 30, 2012 @01:07PM (#40157819) Journal

Yeah, but the new research had to make sure it wasn't the Coriolis force!

• #### Re: (Score:2)

So? If you were in a position to justify such an experiment, wouldn't you do it, without any regard to prior studies? Count me as one vote for the "best experiment subject of the year" award.
• #### Re: (Score:2)

Link (in there) doesn't work anymore, and I can't find it.

• #### Re: (Score:2)

The Australians figured it out 12 years ago

http://science.slashdot.org/story/00/01/11/2156213/why-bubbles-in-guinness-fall

Yes but the math starts getting real dense midway in just about the time the author starts using 'yourmothersawhore' as a delta function. The last few pages seem to be completely unrelated work on chaos theory but I'm not sure that was intentional.

• #### Re: (Score:3, Funny)

The underlying principle in science is to form a model and then test for confirmation or error. Clearly these dedicated professionals were testing in the name of science in case other forces were involved! In fact, I should do my part and run some tests of my own. I might also test some principles regarding gravity while I'm at it....
• #### Re: (Score:3)

It's easy to see why this would be so in Australia. They're on the bottom of the world, and bubbles go up.
• #### American fluid dynamicists did it first! (Score:5, Informative)

on Wednesday May 30, 2012 @12:37PM (#40157361)

Twelve years ago an almost identical paper was on the office wall of a chemical engineering professor I had in college. I'm mostly kidding with my subject line - I expect there's novelty in the new paper and just want to point out that this has been used as a model system (probably many times) before now.

• #### party pooper (Score:5, Funny)

on Wednesday May 30, 2012 @12:43PM (#40157425)

That's an astout observation!

Hence, no stout for you, mister. ;)

• #### Re:party pooper (Score:4, Funny)

on Wednesday May 30, 2012 @03:44PM (#40160189) Homepage Journal

You sound bitter.

• #### Re: (Score:1)

Lager men than he would overcome that character defect.
• #### Re: (Score:2)

Twelve years ago an almost identical paper was on the office wall of a chemical engineering professor I had in college. I'm mostly kidding with my subject line - I expect there's novelty in the new paper and just want to point out that this has been used as a model system (probably many times) before now.

I believe you are referring to Md Nurul Hasan Khan. In 1999 he published a paper proving Guinness bubbles fall. As far as I know he was the first.

• #### Is it replicatable? (Score:3, Funny)

on Wednesday May 30, 2012 @12:39PM (#40157367) Journal

I believe this study will end up receiving more than its fair share of replication and confirmation studies.

In fact, I can see several follow-up studies on if (and possibly why) this is specific to stout. How about a nice lager "control group" for the lads at table 3?

• #### Re:Is it replicatable? (Score:4, Informative)

on Wednesday May 30, 2012 @01:58PM (#40158509)
It's not because they're stouts, it's because nitrogen is used in making certain stouts (in this case, the title was better than the summary). Non-nitrogen stouts won't work. For example, Left Hand Brewery has a Milk Stout and a Milk Stout Nitro; only the Nitro has the cascade. Unless you find a nitrogen lager, there's really no experiment to be had.
• #### Re:Is it replicatable? (Score:4, Informative)

on Wednesday May 30, 2012 @02:08PM (#40158649)

Boddington's pub ale uses nitrogen, and it exhibits the same behaviour as Guinness.. it's interesting to see the effect in a clear fluid

• #### Re: (Score:2)

the category of ale encompasses many beers, including stouts like Guinness.

It does not, however, encompass lager, which if Budweiser is representative, is a category of beer whose terrible flavor is only mitigated by its incredible weakness.

• #### Re: (Score:3)

Fortunately, Budweiser is not representative. Lager comprises the Bavarian pale lagers, including Maerzen, i.e. the Oktoberfest beer. Heck, bock beer is a subcategory of Lager - not exactly incredible weak there...
• #### Re: (Score:2)

An ale is still not always a stout. If a stout is basically an ale made with roasted malt, the question could be it's something to do with the malt and not the yeast.

Bud is disgustingly weak as far as flavor, but higher alcohol content than I thought. (5%abv) I always thought it was around 3 or 4. I'll stick with my 8 - 12% IPA's

• #### Re: (Score:2)

Next study: helium-3 infused stouts vs. non-helium-3 infused stouts.

• #### Mythbusters (Score:5, Interesting)

on Wednesday May 30, 2012 @12:39PM (#40157373)

Mythbusters (accidentally) did it first.

• #### I thought... (Score:3)

on Wednesday May 30, 2012 @12:46PM (#40157465)
I thought it was just a side effect of drinking the stuff.... Like the floor smacking me in the face... Hey, bar-keep! Keep'm coming until the bubbles start sinking...
• #### DO NOT (Score:5, Funny)

on Wednesday May 30, 2012 @12:50PM (#40157527) Journal

...I repeat DO NOT touch a pint glass and an anti-pint glass during a toast.

That is all.

• #### Re: (Score:3)

They'll annihilate each other, leaving you with nothing but a piece of bread.

• #### Re:DO NOT (Score:4, Funny)

on Wednesday May 30, 2012 @02:00PM (#40158541) Journal
Only after a rather stout explosion, though.
• #### Re: (Score:2)

Do not touch pint glass with anti-pint glass in remaining space/time...

• #### Re: (Score:1)

Do not cross the stouts?
• #### Location, location, location (Score:2, Funny)

by Anonymous Coward

Guiness is brewed in Ireland. The bubbles are made in Australia. When the can is opened the bubbles attempt to to up, but they are from Australia so they head the wrong way. Another pint of your finest, barkeep!

• #### Re: (Score:3)

The bubbles are embarrassed at being full of nitrogen instead of carbon dioxide (as beer bubbles should be) and are trying to hide?
• #### Re: (Score:1)

by Anonymous Coward

Qantas entanglement.

• #### Math (Score:2)

Their answer is "because the math says so"?

• #### Negative ninety-nine bottles of beer on the wall. (Score:5, Funny)

on Wednesday May 30, 2012 @01:23PM (#40158071)

in the anti-pint glass the vortex rotates in the opposite direction, causing an upward flow of fluid and bubbles near the wall of the glass

Just don't drink too many anti-pints of beer. I tried it once and woke up with a hell of a hangunder.

• #### Re: (Score:2)

in the anti-pint glass the vortex rotates in the opposite direction, causing an upward flow of fluid and bubbles near the wall of the glass

Just don't drink too many anti-pints of beer. I tried it once and woke up with a hell of a hangunder.

Hangin out on the Disc [lspace.org] again? Bugarup. Millenium hand and shrimp, I says! :)

• #### This could put Ireland back into recession (Score:1)

At the end of the paper they tantalisingly open the door to the possibility that there might exist a glass which would allow Guinness to settle more quickly. If such a glass were discovered, Irish barmen (well, all barmen really) would be able to pull pints more quickly. This means that fewer barmen would be required to man a bar so barmen would lose their jobs, increasing unemployment and probably plunging the country (perhaps the world) further into recession. Risky research.
• #### Re: (Score:1)

All pints of Guinness can be pulled quickly almost independently of the shape of the glass, the current two-stage pouring process was introduced as a marketing ploy some decades ago to make the beer somehow special. I'm not denying that the beer is special, only that it needs to be poured in any special way.

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