Please consider the findings of the study "Bubble nucleation in stout beers," written by some researchers connected to the University of Limerick, Ireland:
We extend the mathematical model of bubble nucleation in carbonated liquids to the case of two gasses and show that this nucleation mechanism is active in stout beers, though substantially slower than in carbonated beers and confirm this by observation. A rough calculation suggests that despite the slowness of the process, applying a coating of hollow porous fibres to the inside of a can or bottle could be a potential replacement for widgets.
These may seem like the most complicated two sentences ever written about beer.
But nonetheless: the world is given a study, so the world must pay attention--especially when it's a study written by researchers in Ireland on stout. Apparently, when a can of beer is opened, the carbon dioxide bubbles form slowly and they must originate from something called a "nucleation site." Stouts--like the much-beloved Guiness--are "pressurised by a mixture of carbon dioxide and nitrogen," explains a handy post on the topic from MIT's Technology Review, helping us decipher this paper. That's the reason for that special tap when you order the stuff at a bar. Nitrogen makes the bubbles smaller, the drink smoother, your night better, the thinking goes. When stout is bought in a can or a bottle, the silly plastic thing in the opening--what is called a "widget"--makes it so the beverage can form bubbles and a head when poured.
These bold researchers are proposing a paper widget instead of the current plastic one. They have reminded us that there is a science to just about anything. And they have also reminded us why we don't typically drink with mathematicians.