The Michelson-Morley Experiment

Abstract

In the reading selection that follows—taken from Michelson’s Lowell Lectures of 1899, which were published in 1903 in the form of a book entitled Light Waves and their Uses—Michelson describes what is now called the Michelson-Morley experiment. This experiment is seen today as providing compelling evidence in support of Einstein’s 1905 special theory of relativity. Michelson relies almost exclusively upon the wave theory of light, since it is able to account for the interference of light, a phenomenon upon which his apparatus relies. Michelson only mentions the particle theory of light insofar as it provides a simple explanation of the phenomenon of stellar aberration. In the course of the reading, Michelson speaks highly of Fizeau’s 1851 measurement of the velocity of light in flowing water. He does so in order to motivate his own experiments on the speed of light. Interestingly, in the concluding section of this reading, Michelson endorses Kelvin's vortex model of the atom—a theory which treats atoms not as tiny particles, but rather as localized smoke-ring-like excitations. Does Michelson reject the idea of æther?

If this experiment gave a positive result, it would determine the velocity, not merely of the earth in its orbit, but of the earth through the ether.

—Albert Michelson