Type the following query into google: "(100 m) / (50.58 s) * 0.01 seconds in centimeters" (or you can just click)... The answer you get back will look like this:

What does this equation tell us?

Michael Phelps swam the 100m butterfly in 50.58 seconds, at an average rate of 1.97 meters per second (or roughly 6 feet every second).

He won this race by 1/100th of a second.

That means that he won this race by approximately 1.97706603 centimeters. For those of you not quite sure how far that is, (just ask Google "1.97706603 centimeters in inches") it's basically 3/4". This is remarkable for two reasons.

First, if they had touched closer to 3/8" apart, 1/200ths of a second would have elapsed between the touches, and the calibration of the timers would not have been able to tell the times apart-- that is, Cavic's time would likely have been the same as Phelps if they had touched any closer than 3/8ths of an inch because at the (average) speed they were swimming, such distance would represent a quantum of time less than 1/100th of a second.

Second, the irony is that the only reason he won by that much is that he thought he lost:

As soon as I took that last half stroke, to be honest, I thought I'd lost the race. I guess that was the difference because if I had glided then I would have came up short.

If he didn't think he had lost, he wouldn't have taken another stroke, and wouldn't have beaten Cavic.

Amazing.