Uncle Ben from the Filipino side of the family, an engineer and beer scientist, sends this Reuter's article on scientific analysis:
It depends on the shape of the glass...more at PsyOrgLONDON - People celebrating St. Patrick’s Day Wednesday can cross one topic of conversation off their lists.
Guinness bubbles really do sink.
Scientists said Monday they had finally proved that the dark stout’s creamy bubbles defy expectations and flow down instead of upwards.
(Phys.org) -- Why do the bubbles in a glass of stout beer such as Guinness sink while the beer is settling, even though the bubbles are lighter than the surrounding liquid? That’s been a puzzling question until now, as a team of mathematicians from the University of Limerick has shown that the sinking bubbles result from the shape of a pint glass, which narrows downwards and causes a circulation pattern that drives both fluid and bubbles downwards at the wall of the glass. So it’s not just the bubbles themselves that are sinking (in fact, they're still trying to rise), but the entire fluid is sinking and pulling the bubbles down with it.Video: