ATRACTOR

Instructions

Double-click at any point to stop the animation or to resume it. To change the vertices of the initial tetrahedron (blue dots), stop the animation, drag them, and resume the animation.
Note: The animation runs only when the mouse pointer is over it.

Note that the black dot, besides being both the center of gravity of the initial (blue) tetrahedron and the new (red) tetrahedron, is also the center of a homothety of ratio \(-\frac{1}{3}\) that maps the blue tetrahedron into the red one. The animation shows this.