If you walk around with a glass of beer and a glass of coffee, you're more likely to spill your coffee than you beer. Why? 4 physicists think that they have an answer. Alban Sauret, Francois Boulogne, Jean Cappello, and Howard Stone recently presented their findings at a conference. Their studies suggest that the foam on the surface of beer dampens movement. The thicker the foam, the less movement and less spillage. Rachel Nuwer writes for Smithsonian:
Just as solid foam reduces noise by absorbing sound waves, liquid foam does the same for motion. The researchers discovered foam's insulating effects by performing controlled lab experiments on coffee and beer. They used high speed cameras to record the waves of motion that rocked through the surface of coffee, an amber beer and Guinness. The more foam that was present, they observed, the more energy was absorbed and the less sloshing occurred.
-via David Thompson