Now,  from the Plate Theory (see Plate Theory and Extensions),

                                ,

where (n) is the variance of the Gaussian curve.

Now, (n) is the volume variance of the Gaussian curve (i.e., ), then, by comparison, (2D_mt) will be the length variance  of the concentration curve where (t) is the elapsed time. Consequently, if a differential equation of the form  is derived that describes some form of dispersion that arises from a random diffusion process, then the solution will be a Gaussian function and, more important from the point of view of the Rate Theory, the Gaussian curve will have a variance given by (2D_mt).