3. Multistability
Different dances are possible to the same music!
People intuitively believe that two identical copies of a system put into the same environment will behave in the same way. Our demonstration shows that this is not true even not for waterwheels. It gets plausible that this simple idea is highly questionable for more complicated complex systems as e.g. the climate system, an ecosystem, an animal, etc. In addition, the simulation shows that complex systems react delayed and so make it difficult to relate cause and effect! Further, the transition between order (stationarity) and chaos is abrupt, it happens within a short time interval. However, the abrupt transition is announced by increasing fluctuations (more and more irregular angular velocity), so called "critical fluctuations" well known from very different physical systems (e.g. density fluctuations in a fluid near the thermodynamical critical point).
Hints for demonstrations
By selecting Multistability after stopping the waterwheel and starting it again, it will steadily turn clockwise. Increase water supply rate from the presetted 320 g/s to 390 g/s and wait 60 s. Then reduce the rate to the former 320 g/s. It seems nothing important to happen, but about 30-60 s later, the waterwheel changes direction and begins a stable pendulum movement (two boxes are all the time empty). This phase transition is the late result of increasing supply rate during limited time only. Please realize that the initial steady state is very stable by "kicking" the waterwheel! The same is true for the pendulum state.
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