Impossible motion: magnet-like slopes

Impossible motion: magnet-like slopes: "

I favorited a YouTube video: Winner of the Best Visual Illusion of the Year Contest 2010
http://illusioncontest.neuralcorrelate.com
Koukichi Sugihara
Meiji Institute for Advanced Study of Mathematical Sciences, Japan

In this video, wooden balls roll up the slopes just a...

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