Scientists finally reveal why bubbles in Guinness go down instead of up
Published 16/04/2015 | 10:32
Experts have finally answered the pervasive question of why the bubbles in a pint of the black stuff defy the law of physics.
Members of the Royal Society of Chemistry investigated pints of Guinness with the hope of understanding why bubbles in the stout go down instead of up.
The London based research group used a camera which magnified the bubbles to 1000 percent their normal size in order to get a better look at the behaviour.
They used a super-fast camera that magnified the bubbles to 1000 percent of their normal size and zoomed in on their behavior.
The researchers found that the bubbles rose rapidly at the center of the glass, pulling the surrounding liquid with them and setting up a circulating current, while the outlying bubbles moved downwards.
''I'd wanted to try and capture the bubbles going down as I had obviously wondered whether it really did happen, having drunk a few Guinness during my time at university, or whether it was an optical illusion created by the waves in the drink that don't contain any bubbles,” senior researcher Dr Andrew Alexander said.
''To capture the image, we had a camera which uses 4,500 frames a second and a zoom lens of times 10. When we saw the bubbles really were going down, I was immeasurably happy,” Dr Alexander added.
''We then filmed it as a colleague pointed out that people might have said all we did was turn the photos upside down. But it's true. The circulation cells in the glass provide the same effect like you see in a tornado.''
Speaking about the results of the innovative study, a spokesman for the RSC said: ''Guinness is good for this experiment as the bubbles are small, due to being released at high pressure by the widget and therefore easily pushed around.
''The gas in the bubbles is also important. In lager beers, the gas is carbon dioxide which is more easily dissolved into the liquid. The gas in Guinness bubbles is nitrogen - not so easily dissolved and therefore not prone to grow larger.”