He is also known for the Kardar–Parisi–Zhang equation modelling stochastic aggregation. From the point of view of complex systems, he worked on the collective motion of animals (such as swarms and flocks).
He is renowned for his work on the Kardar–Parisi–Zhang equation, which describes stochastic aggregation.  From a complex systems standpoint, he investigated the collective movement of animals like swarms and flocks.