 Three objections have been levelled against this line of thought. First, it is pointed that assuming ergodicity is too strong in two ways. The first is that it turns out to be extremely difficult to prove that the systems of interest really are ergodic. Contrary to what is sometimes asserted, not even a system of \(n\) elastic hard balls moving in a cubic box with hard reflecting walls has been proven to be ergodic for arbitrary \(n\); it has been proven to be ergodic only for \(n \le 4\). To this charge one could reply that what looks like defeat to some, appears to be a challenge to others. Progress in mathematics may eventually resolve the issue, and there is at least one recent result that justifies optimism: Simanyi (2004) shows that a system of \(n\) hard balls on a torus of dimension 3 or greater is ergodic, for an arbitrary natural number \(n\).