Consideration of the physics and topology of the two-dimensional grain grow
th suggests that a stochastic expression is required for individual grain g
rowth rates. Two sources for the stochastic behaviour are topological switc
hing events and the average linear correlation between grain size and topol
ogical class. A size-based continuum stochastic formulation is presented on
the basis of topological correlation. This analysis leads to a Fokker-Plan
ck equation for the size distribution, which yields a unique self similar a
symptotic state that is reached from arbitrary initial states. Grain size d
istributions obtained from these considerations are in good agreement with
experimental observations.