Berni Julian Alder is an American physicist specialized in statistical mechanics, and a pioneer of numerical simulation in physics. Alder was born on on September 9, 1925 in Duisburg, Germany to Jewish parents, a chemist and a homemaker. He obtained a B.Sc. in Chemistry from the University of California at Berkeley and a master's degree in chemical engineering from the same institution in 1947.  He was elected a Fellow of the American Academy of Arts and Sciences in 2008. In 2008, he was awarded the National Medal of Science.