Robert Millikan

Millikan's oil-drop experiment, conducted at the University of Chicago around 1909, measured the electric charge of individual electrons by observing charged oil droplets suspended between two metal plates in an electric field. By balancing the droplets' weight against the electric force, Millikan determined that electric charge is quantized in discrete, equal units.

Millikan received the 1923 Nobel Prize in Physics for his measurements of the elementary electric charge and his work on the photoelectric effect. His photoelectric experiments provided experimental confirmation of Einstein's 1905 prediction that light energy is quantized in discrete packets, or photons.

Historians who examined Millikan's original laboratory notebooks found that he selectively reported data, omitting measurements from roughly a third of his observed droplets that did not fit his expected results. While the fundamental conclusions of his work have been confirmed by other methods, his data handling raises questions about scientific ethics and the sociology of scientific replication.

Millikan worked at the University of Chicago for much of his career before moving to the California Institute of Technology (Caltech) in 1921. At Caltech, he served as chairman of the executive council, effectively the head of the institution, and helped build it into one of the world's leading scientific research universities.