Alan and Heinrich Jaegar scrutinize sand on the shores of Lake Michigan

Sand. "It's one of the best substances around," says Sidney Nagel, a professor of Physics at the University of Chicago's Materials Lab. When Nagel and his colleague Heinrich Jaeger look at sand and other types of grains, a whole host of little questions spring to their minds. Why does wet sand create a halo effect around your feet when you walk on the shore? Why do Brazil nuts always rise to the top of a can of mixed nuts? Why do coffee spills leave rings when they dry?

In "Grains of Inspiration," Nagel and Jaeger attempt to answer all these little questions and explain their bigger applications to Alan Alda. A clear plastic bottle filled with water and sand provides a glimpse of the beach beneath your feet; a shaking machine reveals how a larger objects "float" helplessly on top of smaller ones; a microscope reveals what's really going on as a coffee spill dries into its characteristic ring.

Brazil nuts "float" to the top of a shaken can of nuts

Why should we care? It's vital that drug manufacturers understand how different particles mix when stirred. Likewise, the way coffee stains dry might have important applications in manufacturing ultra-fine electronic circuits. Just another example of little questions with some big answers.