Olympic victory often comes down to the slimmest of margins - 1/100ths of a second separating the heroes from the also-rans. With so much resting on times, the measurements have to be more accurate than ever.
When Kelly Holmes became the 800 metre Olympic champion, she did it by running a race 5/100ths of a second faster than her nearest competitor. That's 0.05 seconds - far less time than it took you to read the word "Holmes" just now.
In everyday life, that amount of time is absolutely insignificant. Your boss won't berate you for sending an e-mail 0.05 seconds late. If you miss 0.05 seconds of your favourite soap, you won't miss a vital plot twist.
But when it comes to sport, those tiny gaps in time can mean the difference between victory and defeat; a world record and a decent effort.
Such measurements are possible only with modern technology, with time being split into ever-smaller parts.
When the first of the modern Olympic Games was held more than 100 years ago, such detail was impossible - the times of winning athletes recorded with far less accuracy.
It was at the 1912 Stockholm Olympics that electric stopwatches were first used instead of basic hand-held devices. A camera, to capture early photo finishes, was also introduced.
Men's 100m Olympic winners
1912: T Burke (USA) 12.0
1924: H Abrahams (GB) - 10.6
1960: A Hary (Ger) - 10.2
1992: L Christie (GB) - 9.96
2004: J Gatlin (USA) - 9.85
Since they were operated by human beings, however, there was a considerable margin of error - about 0.2 seconds.
Given that the 100m race lasts for about 10 seconds, this could be equivalent to two metres - a massive distance for the event.
Electronic timers were first used in the 1972 Munich Olympics, though the principle of quartz timekeeping dates back to the 1920s, when it was accidentally discovered by radio engineers looking to ensure reliable signals.
Based on the constant and incredibly regular vibrations of quartz, these devices took timekeeping to a new level, improving accuracy to 0.01 seconds.
Today they are capable of recording sporting times to within 1/1000th of a second, or 0.001 seconds, on the Olympic scoreboard.
In Athens, a camera scans the finish line up to 2,000 times per second and records when each runner's torso crosses the line.
As training regimes get tougher, equipment more specialised and athletes more professional, records are constantly being broken.
Today's men's 100m race is a fast-paced sprint that must be won in a time of under 10 seconds.
Would the result have been different in 1912?
Four years ago, the USA's Maurice Green won in 9.87 seconds.
In the first modern games, in 1896, Thomas Burke of the USA won with a time of 12.0 seconds.
As athletes have got faster, the times that they register have got more accurate. In 1972, with the introduction of electronic timepieces, it was at last worthwhile to record athletes' times to two decimal places rather than one.
But what if, eventually, records stop being broken? Technology and human endurance have limits, after all.
In such a case, it seems likely that smaller units of time will become ever more important, as it becomes harder and harder to break existing records.
So is the recording of time likely to develop even further at sports events? There is certainly the capability for it to do so.
The measurement of time has been getting more accurate at an astounding rate.
New names have had to be invented for new and smaller periods of time as they are discovered. Time can now be measured accurately in the smallest amounts - all the way from milliseconds (one thousandth of a second) down to attoseconds (one billionth of a billionth of a second).
David Rooney, the curator of timekeeping at the Royal Observatory Greenwich, says that timekeeping has undergone a "step change" in the past 50 years.
"The very definition of 'time' has changed, from being an astronomical measurement to a physical measurement", he says.
'Physical' in the sense that modern time is calculated from such things as the vibrations of atoms, rather than from astronomical observations.
Accuracy is being taken to new lengths, based on the constants of the universe. Timepieces around the world are kept constant by signals from the latest atomic clocks.
At the National Physical Laboratory, scientists are working on a clock that is so accurate that it will lose only one second in the remaining lifetime of the universe.
But it may be a while before we see these breakthroughs put to use at the Olympics.
The chances of two athletes achieving the same times to the nearest attosecond are, to put it mildly, remote.
But technological developments in time have already made things better.
Let us return to Kelly Holmes. Her winning time in the 800m was 1.56.38, beating Hasna Benhassi with 1.56.43.
Were those times to have been recorded in 1912, they would have been rounded to the nearest 10th of a second, giving us times of 1.56.4 and 1.56.4.
Had Kelly run in 1912, her victory might not have been so clear-cut.
There are problems at the other end of the scale too. A millisecond is an imperceptibly tiny length of time, easily accounted for by minute differences in a track or lane.
At the 1984 Los Angeles Olympics, Americans Nancy Hogshead and Carrie Steinseifer were both awarded gold medals after they recorded equal times to the hundredth of a second in the 100m freestyle. They never found out who won to the thousandth.
And when dealing with lengths of time so small, is there any benefit in knowing? "It wouldn't have said who really won", Hogshead later told reporters.
"All it would have told us is that maybe somebody's lane is a thousandth of a second shorter. A hundredth is a tiny amount of time, and a thousandth is a sliver of a sliver."