History lesson / 1931–2019
Loup Verlet
Before physical AI, there was a fundamental challenge: how do we teach a computer to follow the motion of the physical world?
The physicist
Loup Verlet was a French physicist and a pioneer of molecular dynamics: using computers to track interacting particles and study the behavior of matter. Born in 1931, he attended the first Les Houches summer school in 1951 and earned his doctorate in 1957. Much of his research concerned liquids. Les Houches remembrance ↗
1967: a computer becomes an experiment
In a landmark paper, Verlet simulated 864 particles interacting through a Lennard-Jones potential. Their calculated equilibrium properties closely matched those of argon. It was a concrete demonstration that numerical experiments could reveal how physical systems behave. Read the original paper ↗
One small step, repeated
The method associated with his name advances motion in small time steps. In its basic position form, Verlet integration combines a particle’s current position, previous position, and present acceleration to estimate its next position.
His work also used periodically updated neighbor lists, which reduce unnecessary interaction calculations by keeping track of nearby particles. Together, these ideas made molecular simulation more practical. CECAM’s account of his work ↗
Beyond the algorithm
Verlet’s interests extended to the history and philosophy of science, music, and mountaineering. Colleagues remembered both his scientific contributions and his care as a teacher. He died in 2019. Read the CECAM remembrance ↗
A connection to physical AI
For us, this history offers a useful perspective: progress comes from making the physical world tractable, one observation and one step at a time. Simulation, data collection, and annotation are different tools, but each helps turn physical experience into something a machine can work with.