John MacCallum is a composer, media artist, and software engineer based in Falmouth, UK. His work uses technology to probe our relationship to time. At its center is the heart, as timekeeper, material performer, and world-builder. For over a decade that work has been made in collaboration with choreographer and media artist Teoma Naccarato: extended-duration performances inside high-channel-count real-time audio/visual systems. He designs and builds the software these systems run on.