Yanwen Sun

An ordinary camera flash lingers for hundredths of a second, but for atoms, that's an eternity. Inside molecules, electrons jump in attoseconds: billionths of a billionth of a second. To capture that, you need a light pulse shorter than the event itself. Physicists take an electron beam in a linear accelerator and compress it so that individual bunches become thinner than a hair — in time.

In a boron arsenide crystal, the atoms dance a leisurely dance. After a short light pulse, the lattice begins to vibrate, and these vibrations, known as phonons, redistribute energy so unhurriedly that every step seems measured out in advance.