Chemistry professor Richard N. Zare says the study of bubbles is serious stuff, with important industrial and engineering applications. And how better to test whether bubbles can sink than with pints and pints of beer?
Skeptical of Australian researchers who created a computer model in 1999 that showed bubbles in a glass of Guinness draft could flow downward, Zare and former Stanford postdoc Andrew J. Alexander took matters—and glasses—into their own hands. “Indeed, Andy and I first wondered if the people had had maybe too much Guinness to drink,” Zare says. “We tried our own experiments, which were fun but inconclusive. So Andy got hold of a camera that takes 750 frames a second and recorded some rather gorgeous video clips of what was happening.”
It turns out that when a beer is first poured, bubbles go up more easily in the center of the glass than on the sides. As they ascend, they raise the beer, which runs back down the sides, bringing along some small bubbles for the ride. Bottoms up.
