Harold Edgerton was a professor of electrical engineering at M.I.T. who pioneered the use of stroboscopic lights in photography, especially as a means of capturing objects that were moving much too fast to be seen by the human eye. Take this photo of a bullet passing through an apple. Thanks to Dr. Edgerton's work, we can plainly see the moment when the bullet pierces the apple, which would be impossible to see otherwise.
In the following photo, we can see another moment normally invisible to the eye: a golf ball indented by the club at the moment of impact!
Perhaps the most striking images are those he captured for the military as they were testing the atomic bomb. Here is a set of three photographs taken at a speed of 1/100,000,000th of a second:
Above you see the first millionth of a second after the detonation.
In the next millisecond you can see the bomb's energy traveling down the tower's guide wires as the rest of it vaporizes the tower. The desert floor below is instantly transformed into a sea of glass.
A millionth of a second later, the sphere of nuclear destruction completely engulfs the surrounding area, including the Joshua Trees you see silhouetted at ground level which will cease to exist in the next millisecond!
Thanks to the pioneering work of Harold Edgerton, we can now see things that were previously unknown to us, and the techniques he invented are now being used the world over to better understand the amazing world in which we live.