5 Measuring the speed of light

“Time flies. You can’t. They fly too fast.” (Children’s word puzzle)

Background The speed of light is a central physical constant. Several complex experiments were carried out in the second half of the 19th century to measure it, including Michelson’s 100 measurements made in the summer of 1879 (Michelson (1880)), and Newcomb’s measurements from 1882 (Newcomb (1891)).

Questions Are the estimates close to today’s value? How did Michelson’s and Newcomb’s estimates compare? Can the results be treated as independent random samples?

Sources Michelson’s report of 1880 for the U.S. Nautical Almanac Office and Newcomb’s paper of 1891.

Structure Michelson’s results of 100 experiments from 1879 included date, time of day, temperature, and estimate of the speed of light. Newcomb’s 66 experiments of 1882 included date, weights grading the observation quality, observer’s name, and estimate of the speed of light. Some experimental settings and intermediate measurements listed in the original sources have not been included.