- How accurate are track & field records?

- How accurate are track & field records?

Interesting. One excerpt:

They can record to the ten-thousandth of a second, although that level of precision is not commonly used. That's because every track (and every lane) differs in length by a minuscule amount, so two runners who race at exactly the same speed might cross the finish line with times that differ by a tiny fraction of a second. In the 1972 Olympics, for example, two swimmers finished a 400-meter race within two-thousandths of a second—or a few millimeters—of each other. As it turned out, each lane of the swimming pool had been constructed to a precision of just 10 millimeters, so there was no way to determine the winner.