A probability cloud shaped by wave interference periodically collapses into a single point, then re-expands. Particle base positions are seeded on a disk modulated by two interfering sine terms so the resting cloud already resembles a standing-wave probability density. A single eased state machine drives collapseAmount from 0 to 1 and back, moving every particle toward a randomly chosen collapse point, while expanding ripple rings and a flashing marker sell the "measurement" moment.