I’ve heard that weightlessness obtains to the center of the earth. Does the same hold true of every physical object, that is has a weightless gravitational center? I have also wondered how many axes in motion are possible at the same time on a single sphere.
There’s an old saw that teachers would sometimes use, that if there were a tubelike tunnel straight through the Earth, an object which was dropped in would oscillate down one side, up the other, until it finally stopped dead and hovered at the center of the Earth. It’s not true. :^)