The physics of football

Abstract
Bill Shankly, the former manager of Liverpool football club, once said: "Football is not about life or death. It is more important than that." This month at the World Cup in France, millions of football fans will get that same feeling for a few short weeks. Then the event will be over, and all that will remain will be a few repeats on television and the endless speculation about what might have happened. It is this aspect of football that its fans love, and others hate. What if that penalty had gone in? What if the player hadn't been sent off? What if that free kick hadn't bent around the wall and gone in for a goal?