Interestingly (well, to me, at least), I read a recent physics article about an MLS penalty kick that hit one goalpost, ricocheted laterally across the goal to hit the other goal post, and then ricocheted back across the front of the goal, without going in. The author did a calculation based on video analysis of the approach angle and departure angle. He concluded that if the ball had been 40 microns (about 1.5 thousandths of an inch) to the right when it struck the first goalpost, it would have gone in. For reference sake, a typical human hair has a diameter of about 80 microns--so the penalty kick was actually, not just figuratively, a hair's-breadth from scoring.