text: is the crack of a whip produced by it breaking the sound barrier?   it has long been thought that the crack results from the tip of the whip traveling fast enough to break the sound barrier and create a sonic boom. but the new findings suggest otherwise. apparently, it's the loop in a whip that is the real noisemaker  http://www.hypography.com/article.cfm?id=32479   http://www.sciam.com/article.cfm?articleid=00088b33-8e92-1cee-93f6809ec5880000