  We consider diffusion processes with the help of Markov random walk models.
Especially the process of diffusion of a relativistic particle in a
relativistic equilibrium system is considered. We interpret one of the results
as causal Zeno effect for its similarity to quantum Zeno effect. Another
problem we considered is about collision number. Basing on our numerical
results, we propose that in the considered situation the probability density
distribution among different collision numbers is a lognormal distribution.
