The 13 Most Important Numbers in the Universe

2 The Speed of Light


The invention of the cannon during the Middle Ages showed that the speed of sound was finite; you could see a cannon fire long before you heard the sound of the explosion. Shortly thereafter, several scientists, including the great Galileo, realized the possibly that the speed of light was finite as well. Galileo devised an experiment that might well have proved this, involving telescopes and men pointing lights at each other over a great distance. But the extreme rapidity of the speed of light, combined with the technological limitations of the 1600s, made this experiment unworkable.

By the end of the nineteenth century, technology and ingenuity had advanced so far that it was possible to measure the speed of light within 0.02 percent of its actual value. This enabled Albert Michelson and Edward Morley to demonstrate that the speed of light was independent of direction. This startling result led eventually to Einstein’s theory of relativity, the iconic intellectual achievement of the 20th century and perhaps of all time.

It is often said that nothing can travel faster than light. Indeed, nothing physical in the universe can travel faster than the speed of light, but even though our computers process information at near light speed, we still wait impatiently for our files to download. The speed of light is fast, but the speed of frustration is even faster.

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