The Vancouver Sun has an awesome story about mathematicians at the science journal Nature who developed a formula for why beer foam doesn’t last. They take Brevity Gold by calling it ”the von Neumann relation generalized to coarsening of three-dimensional microstructures.” 

From the article: 

The new formula for three dimensions, Srolovitz says, “gives you an exact result for how every individual bubble in the whole array of bubbles will evolve in time.” Beer, meanwhile, behaves like molten metal in the steel mill, going through a transition from tiny bubbles to larger ones under the influence of surface tension. 

Srolovitz says a field trip to the pub can help with basic concepts. “You have to get an idea of the basic geometry. Imagine three bubbles meeting. Generally what you would find is that those three faces of the bubbles all come in at 120 degrees. Four bubbles meet at a point, at 109.5 degrees, and those things are pretty robust. 

“I would say it’s the kind of thing anybody could just sort of stare at, if you’ve had four or five beers and you’re more likely to be in staring mode. It’s really fascinating to watch.” 

Source: The Vancouver Sun / Nature