Why Do Golf Balls Have Dimples?

This is one of the questions that have been bandied around in trivia circles for decades, but I'm yet to find somebody who can explain it in understandable terms to those of us who aren't aerodynamicists. I'm going to try and tackle this issue from a simple, middle-aged golfer's knowledge of the topic.
The story is that two friends were tramping the green of a late 1800s golf course, playing a few holes before retiring to their brandy and cigar studies. On the final hole, the first man takes out his pristine, smooth golf ball and tees up. Catching it pretty, it sails through the sky and lands 125 yards away. His opponent steps up and fishes in his caddy, finding only an old practice ball, scuffed and chipped. Disheartened, he also tees up and catches it a pretty snick. Lo and behold, his ball sails double the distance and comes to land nicely on the green. The baffled friend then begins to use his old ball, word spreads, technique gets out and eventually somebody looks into it.
So what they found was that indentations in the ball cause a change in the way it moves throughout the air. A golf ball is subject to 'drag' from air resistance, a concept we can all get our head around pretty easily from school sciences. The force of the air against the ball will eventually cause it to slow down and gravity will pluck it from the air, probably into the rough. But the other more important type of drag, and the one which is harder to explain; is the drag created behind the golf ball.
I know what you're thinking, why does the air behind the ball affect the forward motion? Well, as the ball parts the air as it moves through it, the air reforms behind it. As the air can't stick close to the ball, swirling currents form which begin to pull the ball backwards (which slows the ball and limits its travel distance!) By 'roughing' the balls surface, turbulence is created around it which overrides the ability of the currents to pull the ball backwards. This cannot happen indefinitely but if your ball can stay in the air for another two seconds or twenty feet, what a huge difference that would make to your drives! Imagine a man running through a crowded city square, full of people trying to trip him over. He would get farther if he had four bodyguards either side, right? Eventually, the bodyguards themselves are going to be tripped and the man will be brought down also; but he'll be running for longer and further with them than without them.
Now as I'm sure you can tell from that analogy, I'm no physicist. But I hope that you'll have a better understanding of the concept. If not, then it doesn't really matter; just hit the ball as hard and as far as you can!

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