Speed of Light

The speed of light is

c = 3.00 x 108 m/s

Galileo tried to measure the speed of light by uncovering lanterns on distant hilltops but realized he was actually only measuring his own reaction time.

In 1675, Ole Roemer, measured the speed of light based upon observations of eclipses of Jupiter's moons.

In 1849, Armand Fizeau measured the speed of light with a rotating toothed wheel.

In 1877, A A Michelson did similar experiments with a rotating mirror. A A Michelson's experiments on the speed of light gave support for Albert Einstein's Theory of Special Relativity. Michelson was the first American to win the Nobel Prize.

These brass markers, across a quad or plaza at the US Naval Academy in Annapolis, mark the location of Albert Michelson's first measurements of the speed of light in 1877.

The Nature of Light


Return to Ch 23, Reflection and Refraction of Light

(c) Doug Davis, 2002; all rights reserved