Like many science geeks, I am often fascinated by the bubbles in my alcoholic drink of choice. In various stages of inebriation, I’ve gone so far as to have hour-long discussions with friends about the behavior of beer bubbles. Since a good friend of mine studies fluid dynamics, these conversations have even led to various equations being scrawled on napkins, sometimes even with lip gloss.
Have you ever noticed that beer bubbles seem to rise up in regular “trains” parallel to the edges of your glass? Or that beer bubbles sometimes migrate downward in your glass, apparently defying the laws of physics? Have you ever wondered why a cheap Bud Light fizzes like crazy (especially when shaken by a drunken frat boy) while a more-refined Guinness produces very few bubbles?
Well, it turns out that some scientists have actually bothered to study the “fizzics” of bubbles in alcoholic drinks. This research even has relevance for geology: understanding the behavior of dissolved gases in liquids is important for knowing how gases behave in natural liquids, such as molten magma or water. I just read a great tongue-and-cheek yet scientifically precise article published by Youxue Yang and Zhengjiu Xu at the University of Michigan. Their article is titled “The ‘Fizzics’ of Bubble Growth in Beer and Champagne.” I’d like to recommend the article and share a quick summary of the research.
The basic findings of Yang and Xu (2008):
1. Because of the higher initial gas concentration in champagne, the “eruption velocity” of champagne is two orders of magnitude higher than CO2-based beer.
2. Bubble growth in Guinness is slow because N2 gas is used for bubble-making. N2 has a lower solubility than CO2, so the manufacturers trap a smaller amount of N2 (relative to CO2) for the same gas pressure. The smaller bubbles which form in Guinness can sometimes be entrained in downward flow, leading to sinking beer bubbles.
Next for scientific research of beer? Perhaps understanding the “fizzics” of beer bubbles in human stomachs. Just an idea.