Do bubbles in Guinness go down?

About the authors

We are both professional scientists, but only amateur Guinness drinkers.  Although we had known for some time about the question of Guinness bubbles defying the norm, our curiousity was rekindled in 1998 with an article by Mark Buchanan for the December issue of The New Scientist (vol. 160, issue 2165, 19 December 1998).  A few members of the Zare lab made a series of preliminary experiments at the local pub one Friday evening, however the results were not conclusive. We felt that the waves of dark liquid that flow down only gave the illusion that the bubbles were going down.  The bubbles were just too small and too fast to see clearly, and by the time you started to form the impression that they were going down, the pint had settled and needed drinking!

In mid-2000 we tried some controlled experiments, using a regular digital video camera with a good zoom lens and a large magnifying desk lamp.  Once again, it was difficult to say whether the waves of liquid were causing an optical illusion...  or were those sneaky bubbles really going down?

In 2002 it was time to call in the heavy guns.  We had heard a report that the sinking bubbles had been modelled using a commercial software package by Prof. Clive Fletcher at the University of New South Wales in Australia.  Well, seeing is believing, we figured, so we set out to get the proof.  You can read more about the filming.

Andy Alexander is a Royal Society University Research Fellow at the University of Edinburgh, Scotland.  You can find out more about Dr Alexander's work at the University of Edinburgh School of Chemistry webpages, or at his research group webpages.

Dick Zare is the Marguerite Blake Wilbur Professor in Natural Science at Stanford University, CA, USA.  You can find out more about Prof. Zare's work at the Stanford University Chemistry Department webpages, or at his research group webpages.