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Pint of Guinness

Science brain teasers require understanding of the physical or biological world and the laws that govern it.


Puzzle ID:#3696
Fun:*** (2.62)
Difficulty:*** (2.36)
Submitted By:cathalmccabe***
Corrected By:cowman12




How can it be possible that the bubbles in a pint of Guinness move downwards?

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Apr 26, 2002

Hmm...By the wording "the bubbles" sort of assumes "all the bubbles" and that is not the case. Should have said "some of the bubbles."
Apr 29, 2002

*ALL* the bubbles do move down. Just not at the same time. Its a circulating motion, all the bubbles do move down.
May 09, 2002

i'll remember that next time i'm getting toasted.
May 21, 2002

You say in the answer that 'some of the bubbles do move down' but in the explanation, state that they 'all' move down - can you clarify which is correct please. Is your assumption that they all move down based on the thick 'head' (like mine!!) in guinness? If so, the 'head' must surely initially be created by bubbles popping, and so the first bubbles out must travel only upwards, creating the 'head'? Oh, by the way - nice teaser, which I had absolutely no idea on, but made me think about it (which is surely the idea.)
May 22, 2002

Alright, at a certain point in time, some of the bubbles are moving down around the outside of the glass, meanwhile, in the center of the pint (you can't see it, most of the other bubbles are moving up. There are more bubbles moving up at any one time (hence the bubbles overall are travelling upwards)
But once these bubbles reach the top of the pint, just under the head, most of them can't escape. The same bubbles spread out at the top, and are forced down the side of the glass. The bubbles that were moving down when they reach the bottom are forced into the centre and travel upwards. They all travel up, and down obviously not at the same time (someone did a thermal study on this I think, you can probably find pictures on the net)
Aug 22, 2002

the quickest way to resolve the talk as to how many go up/down etc is to just drink it. All the bubbles then travel down untill you burp! nice teaser tho'
Aug 22, 2002

This argument should be solved around a good pint of Guinness! Here, I invite you all !! Cheers!
Oct 16, 2004

I'm sorry I thought these were supposed to be teasers...
Oct 16, 2004

so, I should do my own scientific study and drink Guinness tonight...........Brilliant!
Jun 29, 2005

Nice explaination for the inner workings of the pint of Guiness. Note, the bubbles are nitrogen, and not the more common carbon-dioxide in most other beers. It is more dramatic with a draft pint from a keg, and a special tap.
Sep 30, 2006

What's guiness?

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