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Cats fall on their feet, but Baron von Munchhausen could not have pulled
himself by pulling on his hair. Why can cats rotate without angular
momentum while the Baron can not translate without momentum? The naive and
correct answer is that this follows from Newton law on the center of mass
motion. However, it turns out that the notion of center of mass is subtle
and special to Euclidean space. As pointed out by J. Wisdom, the Baron
can swim in empty curved space. The swimming is geometric and related to
Berry's phase.
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