When the 2012 Summer Olympics kick off on NBC and Channel 10 this week, we can expect to see some pretty close finishes - some with just a few hundredths of a second separating the winner from the rest of the pack.
Timed events will be measured to one one-thousandth of a second - one millisecond - and that requires a high-tech timekeeping system built with cameras, lasers, computers and very accurate clocks.
"And the accuracy of today's timing circuitry is a thousandth of a second. So it's one hundred times more accurate than a stopwatch," says Linda Milor, from the Georgia Institute of Technology
To make timekeeping more accurate and precise, engineers use technology to remove the possibility of error.
In track events, an electronic pistol starts the race.
Speakers behind the starting blocks allow each runner to hear the gun at the same time.
If a runner applies pressure in under 100 milliseconds, faster than any human can react, the system signals a 'false start' - and the race is stopped.
At the finish line runners interrupt a laser beam and their time is recorded - while a high-tech camera records more than 2,000 digital images per second.
"So these cameras allow us to get an image and show the result much more quickly than we used to in the past," says Milor.
In swimming events, the start blocks also have speakers and measure reaction times. But at the finish, the athletes stop their own timer by touching pressure-sensitive pads that cover the end of each lane.
High definition video cameras above and below the water also record the finish, taking 100 pictures per second from different angles for judges to examine in a close contest.
With more than 3,000 athletes in 300 events at the 2012 Games in London, it will take timekeeping technology that is both accurate and precise to place the right athletes on the medal stands.
To see more "Science of the Summer Olympics" stories, go to www.NBClearn.com or www.science360.com.