Edwin McMillan was an American physicist born on September 18, 1907, in the United States. He is best known for his work in nuclear chemistry and for being one of the co-discoverers of the element plutonium in 1940. McMillan's research significantly contributed to the understanding of nuclear reactions and the development of atomic energy. In 1951, McMillan was awarded the Nobel Prize in Chemistry for his contributions to the discovery of transuranium elements, which are elements beyond uranium on the periodic table. He also played a key role in the development of the cyclotron, a type of particle accelerator that has been instrumental in advancing nuclear physics.