Stout work by scientists as Guinness riddle solved

Published on Tuesday 16 March 2010 22:37

IT'S not the work of mischievous leprechauns, or the result of having one too many – Guinness bubbles really do go down instead of up, say scientists.

As pubs stocked up with extra supplies of the black stuff in preparation for St Patrick's Day, a Scots scientist offered an explanation for why the famous Irish brew behaves so oddly.

Researchers used a super-fast camera that could zoom in and magnify the bubbles ten times.

The study showed that the more visible outlying bubbles in a pint of Guinness did move downwards, as a result of circulation flow and drag.

At the centre of the glass, the bubbles were free to rise rapidly, pulling the surrounding liquid with them and setting up a circulating current.

Dr Andrew Alexander, senior lecturer in chemical physics at the University of Edinburgh said: "I'd wanted to try and capture the bubbles going down as I had obviously wondered whether it really did happen or whether it was an optical illusion created by the waves in the drink that don't contain any bubbles.

We're pleased to have finally solved this mystery in time for St Patrick's Day when many people will no doubt be enjoying a pint or two."