With a creak of the knees, you bend a fraction closer to the ball. You identify the gradient of the green, size up the distance to the hole and estimate the length and grade of the grass. Following a couple of finely judged practice swings, you're ready to sink the perfectly judged putt.
That may be the time honoured way. But it turns out you've got it all wrong. According to Robert Grober, a physicist at Yale University in New Haven and a world expert on the science of golf, there's a much better way to line up a putt.
Grober's new insight comes from a simple mathematical analysis of the problem. To understand this insight, imagine a flat green with a small drop (ie at a small gradient to the horizontal. Now imagine a ball sitting a few feet from the hole on a line that is perpendicular to the fall.
Obviously, the place to aim for is slightly above the hole, so that the fall steers the ball to its target. And that's about as far as golfers have got with this problem. But Grober has gone further. He places other imaginary balls on an equidistant arc around the hole and then plots the targets to aim for for each one.