Uncertainty Intervals and the Olympics
If I had to pick one topic or way of thinking that engineers and scientists have developed but other folks are often entirely unfamiliar with, I might pick the related ideas of error, uncertainty, and significance. A good science or engineering education will spend a lot of time on assessing the error bars for any measurement, understanding how those errors propagate through a calculation, and determining which digits of an answer are significant and which ones are, as the British might say, just wanking.
It is quite usual to see examples of the media getting notions of error and significance wrong. But yesterday I saw a story where someone actually dusted these tools off and explained why the Olympics don't time events to the millionths of a second, despite clocks that are supposedly that accurate:
Modern timing systems are capable of measuring down to the millionth of a second—so why doesn’t FINA, the world swimming governing body, increase its timing precision by adding thousandths-of-seconds?
As it turns out, FINA used to. In 1972, Sweden’s Gunnar Larsson beat American Tim McKee in the 400m individual medley by 0.002 seconds. That finish led the governing body to eliminate timing by a significant digit. But why?
In a 50 meter Olympic pool, at the current men’s world record 50m pace, a thousandth-of-a-second constitutes 2.39 millimeters of travel. FINA pool dimension regulations allow a tolerance of 3 centimeters in each lane, more than ten times that amount. Could you time swimmers to a thousandth-of-a-second? Sure, but you couldn’t guarantee the winning swimmer didn’t have a thousandth-of-a-second-shorter course to swim. (Attempting to construct a concrete pool to any tighter a tolerance is nearly impossible; the effective length of a pool can change depending on the ambient temperature, the water temperature, and even whether or not there are people in the pool itself.)
By this, even timing to the hundredth of a second is not significant. And all this is even before talk of currents in the Olympic pool distorting times.
