The law that the total amount of angular momentum in a system remains the same (in the absence of any force not directed toward or away from the point or axis about which the angular momentum is referred).
The scientific law that states no angular momentum can appear out of nowhere or disappear
As the centre mass of a rotating body moves closer to the axis of rotation, the velocity of the body increases. This law is demonstrated very vividly by ice skaters when they start to rotate and then pull their arms in to their chest. Search for physics books on Amazon.co.uk