Hi, I found out this paper http://www.pha.jhu.edu/~javalab/pendula/pendula.files/users/olegt/pendulum.pdf [Broken] with this animation http://www.pha.jhu.edu/~javalab/pendula/pendula.files/users/olegt/pendula.html [Broken] At first there is written there, that the area of possible states in some range of energies of pendulum in phase space is conserved due to Liouville's theorem. But at the end there is all new bigger area uniformly filled up. So both can't be right, and I thing that the area in the phase should be conserved. But don't know hot to solve the argument with uniformly filled up the new bigger area which is in agreement with equillibrium statistical physics of microcanonical ensembles . . Thanks a lot for any response!