and now we want to see what happens to a small concentration fluctuation δ δ c = a exp ⁡ ⁡ ( ω ω t ) sin ⁡ ⁡ ( q → → . r → → ) - note that now it has time dependence as a wavevector dependence. Here ω ω is a growth rate. If ω ω < 0 then the perturbation shrinks to nothing, the system is stable with respect to small perturbations or fluctuations, and there is no spinodal decomposition. However, if ω ω > 0 then the perturbation grows and the system is unstable with respect to small perturbations or fluctuations: There is spinodal decomposition.