Robert Millikan

Born on 22 March 1868 in Morrison, Illinois, physicist Robert Millikan is best known for his measurement of the electric charge of the electron, for which he was awarded the 1923 Nobel Prize in Physics . After receiving his PhD in 1895 from Columbia University, Millikan spent a year studying abroad in Germany before returning to the US to take up a teaching position at the University of Chicago. Millikan first distinguished himself as a teacher and textbook author, producing a number of elementary physics texts that would become classics. But he also carried out research. In 1908, drawing inspiration from an experiment carried out in Britain, Millikan began trying to measure the electron’s charge. He electrified two horizontal metal plates and observed the motion of individual water droplets that were suspended between the plates. In late 1909, now working with physicist Harvey Fletcher , Millikan swapped out the water for oil, which didn’t evaporate as quickly. The upgraded experiment allowed Millikan and Fletcher to both measure the elementary electronic charge and confirm that electric charge is carried by individual particles. In 1916 Millikan experimentally confirmed Albert Einstein ‘s equation describing the photoelectric effect. Over his professional career, Millikan made numerous scientific discoveries in the fields of electricity, optics, and molecular physics. In 1921 Millikan moved to Caltech, where, as director of the Norman Bridge Laboratory of Physics and chairman of Caltech’s executive council, he worked to promote science education and to help establish Caltech as a world-class research institution. Millikan died in 1953 in San Marino, California. You can read the obituary that appeared in Physics Today. (Photo credit: Harris & Ewing, AIP Emilio Segrè Visual Archives, W. F. Meggers Gallery of Nobel Laureates)

Date in History: 22 March 1868