After five night shifts of shooting pairs of X-ray pulses through soups of fine sand and gold, Aymeric Robert was tired but exhilarated. The first experiment with an instrument he helped bring into being – the X-ray Correlation Spectroscopy (XCS) instrument at SLAC’s Linac Coherent Light Source – had just ended, launching a new tool for understanding liquids, glasses and other less-than-orderly substances.