Can you undo a spinning top?Shutterstock Imagine spinning a top and then letting it come to rest. Is there a way for you to spin the top again so it ends up in the exact position it started, as if you had never spun it at all? Surprisingly, yes, say mathematicians who have discovered a universal recipe for undoing the rotation of nearly any object. Intuitively, it feels like the only way to undo a complicated sequence of rotations is by painstakingly doing the exact opposite motions one by one. ...