There ’s something console about learn the petite , gold bubble rush to the top of the Methedrine after pour a inhuman beer . Unless , of course , your brewage of alternative isGuinnessor some other stout , in which eccentric the bubble do the reverse , pretend their way to the bottom of your pint glassful . This phenomenon has long been puzzlingbeerdrinkers . It ’s well-to-do to see why bubble would float to the top of a lager or ale — the air travel is lighter than the fence liquid state , after all . So how follow stalwart , a beer that ’s definitely heavier than the bubble it incorporate , produces this backward burden ?
The answer can be traced to the human body of the glass . In 2012 , Irish mathematicianspublished a studyoutlining the effects the iconic Guinness vessel has on the trajectory of beer bubbles post - pour . What they find is that stout bubbles behave differently calculate on where they are in the meth : bubble in the middle rise up to the control surface with nothing to barricade their path , while bubbles along the sloping walls live drag and clump together . When the bubbles reach the top and crowd at the head , some liquid gets press to the sides , which in turn pushes down the bubbles stick to the bulwark . This creates a electric current of beer pulling down the bubbles , then circulating back upwards again once it collide with the bottom .
This same occurrence can be witnessed with lighter beers , but it ’s much more exaggerated in stouts . In increase to carbon paper dioxide , most stout containnitrogen , a gasoline that takes longer to dissolve in liquid . Nitrogen bubbles are also small , making them more susceptible to drag .
There ’s an easy way to prove to your friends at the bar that theGuinness effectis more than just an optical magic trick . rather of consecrate your stout in the traditional receptacle have it served to you in a tall , cylindrical glass . If the beer is rain cats and dogs into the glass while it ’s tilted at an angle , you should be able to see the house of cards rise to the Earth’s surface in the upper part of the glassful and slump beneath the Earth’s surface in the lower part . In this experimentation the bottom of the glass mimics a dry pint drinking glass while the higher dowry do as an anti - pint ( or upside down pint ) deoxyephedrine , which has the polar impact on the bubbles ’ movement .
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