Nature through the looking glass

Handedness--and the related concept of chirality--are double-sided ways of understanding how matter breaks symmetries. Our right and left hands are reflections of one another, but they are not equal. To hide one hand perfectly behind the other, we must face our palms in opposite directions. In physics, the concept of handedness (or chirality) works similarly: It is a property of objects that are not dynamically equivalent to their mirror images. An object that can coincide with its mirror-image ...