Science: More Light on Light

Almost as long as there have been scientists, man has been trying to measure the speed of light. In 1638, Galileo stationed a brace of lantern bearers on hilltops and tried to time their flashes—with no luck at all. Since then, Danes, Frenchmen and Americans have succeeded in narrowing down the figure to generally accepted modern-day figures, but the search for greater precision still goes on.

As scientists refined their measurement skills, they realized more and more the significance of light's speed. By the time it was established that all electromagnetic waves move at the velocity of light in a vacuum, that...

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