Four prominent scientists are being honored today by the U.S. Postal Service with stamps of their own.
Barbara McClintock won the 1983 Nobel Prize in medicine for her discoveries in genetics. She was among the first scientists to study the way genetic material controls the development of an organism.
Josiah Willard Gibbs, who lived from 1839 to 1903, was a pioneer in the study of vector analysis, electromagnetic theory, statistical analysis and thermodynamics. He earned the first doctorate in engineering to be conferred in the United States. He taught at Yale University and was the author of several books and scientific papers.
John von Neumann was one of the top mathematicians of the 20th century. He helped develop a machine that became a model for modern computers, worked with Albert Einstein at the Institute for Advanced Study and was a consultant in the project to build the first atomic bomb.
Richard P. Feynman won the Nobel Prize in physics in 1965 for work in quantum electrodynamics. His work included diagrams that help visualize the dynamics of atomic particles.