The Physics arXiv Blog:
As many drinkers will attest, the bubbles in Guinness appear to sink as the drink settles and the head forms. How can this be, given that bubbles are less dense than the surrounding fluid and so should rise?
Eugene Benilov, Cathal Cummins and William Lee at the University of Limerick made numerical simulations of a pint glass to answer the question. A real-world experiment confirmed their theory.
As a scientist, I’ll have to confirm the results. Then, I will confirm again. Depending on how the day goes, I might need to confirm once more.
You can read the study here.