How random is a lottery machine? What conditions would make it less random?

Professional lottery machines like this one

are accepted as producing genuinely random results. (Or random enough?).

However, it seems like the results are a largely a product of Newtonian mechanics, and are thus in some sense deterministic.

The question I have, what conditions would make them less random (short of actually rigging them) For example, how random would they be if they were operating in a vacuum?

• While Newtonian mechanics is deterministic, the collisions in the machine cause extremely sensitive dynamic conditions which cause even the smallest differences in the initial conditions to blow up to a basically random position of the balls after a few collisions. The mathematical description of this sensitivity is called Lyapunov exponent and it describes how fast two trajectories of the system that are infinitesimally close in the beginning would diverge. One can, of course, rig the system by making some of the balls much heavier, but that is checked by officials. – CuriousOne Jun 3 '15 at 5:47