Physics: 1923

Millikan, Robert Andrews pronounced MIHL uh kuhn, (1868-1953) was a distinguished American physicist. He is noted for his measurement of the electrical charge carried by the electron and for his experiments with cosmic rays. Millikan won the Nobel Prize for physics in 1923.

Millikan's Nobel Prize work included a series of experiments, begun in 1909, to study the charge carried by an electron. He sprayed drops of oil into a special chamber and measured how the charges carried by electrons in the drops affected the drops' fall. Millikan's prizewinning work also included another group of experiments that helped prove Albert Einstein's mathematical explanation of the photoelectric effect (see EINSTEIN, ALBERT).

From the 1920's through the 1940's, Millikan compared the intensity of cosmic rays at various latitudes and altitudes. The data Millikan collected helped scientists study how the earth's magnetic field deflects cosmic rays as they arrive from outer space.

Millikan was born in Morrison, Ill. He attended Oberlin College and received a Ph.D. degree from Columbia University in 1895. He taught at the University of Chicago from 1896 to 1921. From 1921 to 1945, he served as the head of the California Institute of Technology.

Contributor: Daniel J. Kevles, Ph.D., Professor of Humanities, California Institute of Technology.