In physics, Landau damping, named after its discoverer, the eminent Soviet physicist Lev Davidovich Landau, is the effect of damping (exponential decrease as a function of time) of longitudinal space charge waves in plasma or a similar environment. This phenomenon prevents an instability from developing, and creates a region of stability in the parameter space. It was later argued by Donald Lynden-Bell that a similar phenomenon was occurring in galactic dynamics, where the gas of electrons interacting by electro-static forces is replaced by a "gas of stars" interacting by gravitation forces.
Read more about Landau Damping: Wave-particle Interactions, Physical Interpretation, Theoretical Physics: Perturbation Theory, Mathematical Theory: The Cauchy Problem For Perturbative Solutions