When a structure gets so small that one of its dimensions extends only a billionth of a meter, odd things happen. Quantum effects that may be swamped in the big world now play a dominant role; common-sense expectations of how materials ought to behave break down. It's a situation that delights theorists like Marvin Cohen and Steven Louie, professors of physics at UC Berkeley and members of the Lab's Materials Sciences Division, who study the behavior of all sorts of materials-nanostructures prominent among them.