public UniverseState createEmptyUniverseState() {
Set<TreeState> trees = new HashSet<TreeState>(0);
Set<TreeLeafState> fallenLeaves = new HashSet<TreeLeafState>(0);
EnvironmentStateFactory envStateFactory = new EnvironmentStateFactory();
EnvironmentState environment = envStateFactory.createEnvironmentState();
return new UniverseState(UNIVERSE_COUNT++, 0, trees, fallenLeaves, environment, new TimeCounterState());
}