Roland Piquepaille writes "Yesterday, I told you about virtual beer. Today, we follow two North America researchers who are studying the physics of real beer bubbles. 'Singly scattered waves form the basis of many imaging techniques such as radar or seismic exploration.' But pouring beer in a mug involves multiply scattered acoustic waves. They are more complex to study, but they can be used to look at various phenomena, such as predicting volcanic eruptions or understanding the movement of particles in fluids like beer. They also could be used to monitor the structural health of bridges and buildings or the stability of food products over time. Read more for additional references and a photo showing how the researchers monitor beer bubbles."