Y. Yu

Inside a tokamak, a giant magnetic donut, plasma is heated to hundreds of millions of degrees. It doesn't touch the walls; it floats in a vacuum, held by invisible magnetic fields. But plasma is finicky: a slight change in current or pressure and its shape starts to wobble like jelly on a plate.

A tiny ghostly particle zips through a piece of germanium. Usually it leaves no trace, but sometimes, like a billiard ball, it smacks into an atom's nucleus. The nucleus recoils, and that jolt can be detected. At Oak Ridge National Laboratory, the Ge-Mini detector caught such recoils for two years. Neutrinos are the most elusive of known particles.