Xinghua Shi

Two sheets of paper stacked together start to creep ever so slightly over each other when heated. That's roughly how layers of molybdenum disulfide, a material one atom thick, behave. At room temperature, they spontaneously slide at a speed of about one meter per second.

Proteins, like people, have family trees. Two proteins performing the same job in different organisms descend from a common ancestor. By comparing their sequences, you can reconstruct that history. But when proteins diverged long ago, standard methods lose the trail: so many differences pile up that the signal fades, like old photographs yellowing.