Think it doesn’t take matrix mechanics to understand a simple spinning top? Think again. I studied physics for 4 years of undergrad and 6 years of graduate school, but it comes as a complete surprise to me that

A spinning object in free space with its nose forward will turn itself around so it is spinning in the same direction nose backward, and will continue indefinitely forward…backward…forward…backward.

(As it flips, the angular momentum is conserved so it is always spinning in the same direction. In other words, if you are looking at it from the nose and it is spinning clockwise, you will find yourself looking at the tail, but it is still spinning clockwise.)

This is true of any object that has 3 different moments of inertia along its 3 principal axes. In the video, a wingnut is the example.  In fact, the phenomenon was discovered by a Russian cosmonaut who watched a wingnut spinning inside his spacecraft.

The finding was classified and kept secret by the Soviet Union for several years, for fear that the finding applied to the earth. Maybe the earth periodically flips around so its North pole is down and its South pole is up.

The video argues, tentatively, that this has not happened in the past and presumably is not going to happen.

1 thought on “Spinning

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