Albert Michelson-

He was born in December of 1852. He performed early measurements of the velocity of light with amazing delicacy and in 1881 he invented his interferometer for the purpose of discovering the effect of the Earth's motion on the observed velocity. In cooperation with Professor E.W. Morley, and using the interferometer, it was shown that light travels at a constant speed in all inertial systems of reference. The instrument also enabled distances to be measured with greater accuracy by means of the length of light-waves.

Source: http://nobelprize.org/nobel_prizes/physics/laureates/1907/michelson-bio.html