A. Sokolov

At night over the Siberian taiga, a faint blue light sometimes flickers. It's not the aurora borealis but a cosmic-ray shower: a single particle from deep space slams into the atmosphere and shatters into millions of secondary particles. They race toward the ground in a broad front, like a ripple from a stone dropped into water, and make the air glow.

At Japan's KEK laboratory, electrons and their antimatter counterparts, positrons, collide inside the Belle II detector. In such collisions, new particles are born for a fleeting moment. Among them is J/ψ, a bound state of a charm quark and its antiquark.