"Put the egg down on a smooth, hard surface and set it spinning. ...[W]hen you stopped the raw egg, you only stopped the shell. The liquid never stopped swirling... so... the shell started rotating again... dragged around by its insides. ...It is a principle of physics that objects continue the same... movement unless you push or pull on them. ...[[w:Angular momentum#Conservation of angular momentum|[C]onservation of angular momentum]]."