ABSTRACT
In the 1880s two Americans, Albert Michelson and Edward Morley, equipped with nothing more than a large wind-up clock and some mirrors, set about measuring the speed of light. Knowing, as we all do, that speed is relative,* they expected to find a discrepancy between the speed of light coming from the sun with the additional benefit of the earth’s spin, and as viewed with the earth’s spin whisking the observer in the opposite direction. (And the speed of the earth is considerable. It’s only because everything is already moving in harmony with it that we don’t normally notice it.) Try as they might, pointing the mirrors this way and that, even using a multi-sided rotating mirror in between to increase the distance the light was measured over and so on, neither Michelson nor Morley could find any significant difference in the measured speed of light. It always seemed to go everywhere at about 300,000 kms a second.
