Credit: Image courtesy of Derek M. H. Hung.
Still of superimposed videos of the mass/spring experiment described in, “A key step toward understanding the development of heavenly bodies.” In the videos, the untethered sphere moves farthest from the center post and closest to the edge. However, when the angular momentum is calculated in each case, the weakly-tethered mass gains angular momentum and becomes relatively unstable while the untethered one does not.