Eos, Transactions American Geophysical Union

The Newcomb-Michelson velocity of light experiments



In 1877, at age 42, Simon Newcomb became the superintendent of the Nautical Almanac Office (NAO), U.S. Naval Observatory in Washington D.C. That same year, at age 25, Ensign Albert Michelson began his new assignment as a professor of physics and chemistry at the U.S. Naval Academy in Annapolis, Maryland [Reingold, 1964]. While they worked for the same agency less than 1 hour apart by train, the two men lived in very different worlds. Newcomb had already achieved international acclaim for his studies of the orbits of Neptune and Uranus and had his choice of any number of prestigious and powerful positions at scientific institutions and astronomic observatories throughout the nation. As a junior naval officer Michelson could, at best, expect to spend a few years teaching at the Naval Academy before being reassigned to sea duty. Within 2 years of graduating, Michelson had already served aboard five ships of the line, sailing to ports as distant as Rio de Janeiro [Livingston, 1973]. Newcomb had direct access to the secretary of the Navy and members of Congress, and when he learned that Michelson had begun to work on velocity of light experiments, he did not hesitate in having the young ensign detailed to the Naval Observatory. Together they assembled and perfected an apparatus that measured the velocity of light more accurately than had ever been possible before, and the value obtained from the complete set of experiments performed in Washington—299,810 km/s—was not bettered for more than 4 decades.