Last Wednesday, U.S. Olympic swimmers Michael Phelps and Ryan Lochte will dove into the preliminary heats of the men's 200-meter individual medley for a much-anticipated showdown between rivals. Less than one-tenth of a second separated these swimmers the last time they competed in this event: Phelps achieved a time of 1:54.84 at the Olympic Trials in June, with Lochte close on his heels at 1:54.93.
In 2008, Phelps secured a gold medal in the men's 100-meter butterfly with an amazing last-second push that got him to the pool wall exactly 0.01 seconds before Serbia's Milorad Cavic.
With champions separated by less time than it takes to blink an eye, how do Olympic judges pick the winner? The answer is in technology: High-speed cameras, lasers and sensors all work together to mark the most accurate and precise times possible for the athletes. [Video: Clocking Olympic Champions]
"It's incredibly important, because the level of accuracy that is required is in the hundredths to thousandths of seconds," Georgia Tech electrical engineer Linda Milor said in an interview with the National Science Foundation. "Those levels of measurement require a very, very high level of precision and a very, very high level of accuracy."
The Olympic clocks are 100 times more accurate than a regular stopwatch, Milor said. Accuracy is a measure of how true to the "real" time the clock can record. Precision is the ability to get the same measurement over and over and over again.
In London, incredibly sensitive sensors are measuring the precise start and stop times for athletes, from the starting blocks used by track sprinters to the bar code-like radio frequency identification (RFID) tags worn by the marathoners and bikers. These tags transmit data about a racer's location to antennae located along the course.
In the pool, swimmers stop their own timers when their outstretched hands tap against the wall, which is embedded with sensors that convert the pressure of their touch to an electrical impulse.
"Essentially, it's a mechanical problem that has to convert to an electrical problem, which is challenging," Milor said.
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Severe thunderstorms capable of causing property damage and flooding will swing into the southeastern United States and Ohio River Valley into Sunday night.
Dangerous thunderstorms and flash flooding will continue to threaten lives and property across the central United States through Saturday night.
While a storm will douse outdoor plans and lead to flooding on some of the Hawaiian Islands, enough rain may fall to ease drought conditions into the start of May.
Milder air will erase the recent chill and snow across Germany by May Day, though rain threatens to spoil the holiday for western and southern areas.
Temperatures will be put on a roller coaster ride in the northeastern United States through the start of May, delivering bouts of summerlike warmth.
While the recent cold snap will be over, bouts of rain will persist and threaten to disrupt outdoor plans across the United Kingdom during the Bank Holiday weekend.
It will feel like the calendar has been turned back to winter instead of moving ahead to May as snow sweeps across the central United States into Monday.
At least eight people are dead after a Cuban military plane crashed in western Cuba on Saturday.