  The scattering of coherent X-rays from dynamically evolving systems is
currently becoming experimentally feasible. The scattered beam produces a
pattern of bright and dark speckles, which fluctuate almost independently in
time and can be used to study the dynamics of the system. Here we report
large-scale computer simulations of the speckle dynamics for a phase ordering
system, using a two-dimensional model quenched through an order--disorder
transition into the two-phase regime. The intensity at each wave vector ${\bf
k}$ is found to be an exponentially distributed random variable. The scaling
hypothesis is extended to the two-time correlation function of the scattering
intensity at a given wave vector, $Corr({\bf k};t_1,t_2)$. The characteristic
decay time difference for the correlation function, $|t_1 - t_2|_c$, is found
to scale as $k|t_1 + t_2|^{1/2}$.
