The rhythmograms by Heinrich Heidersberger (1906–2006) are intricately curved compositions of pure light that weave abstract figures, organisms, and spaces. The artist created these complex light patterns during the fifties and sixties, capturing the invisible and elusive worlds of time and motion in a single frame. He drew the rhythmograms using an enormous deconstructed photographic machine of his own design. Outfitted not with a camera but instead with an ingenious, room-sized mechanical apparatus to trace the geometry of delicate waves and oscillations, the machine reproduced the elegant orbit of a single ray of light on a photographic plate. Widely known as an architectural photographer of postwar modernism, Heidersberger’s little-known rhythmograms comprise a fascinating bridge between the work of early modernists and the future of algorithmic art and architecture. This is the first critical study of his rhythmograms in all of their delicate detail.