Rudolf Ernst Peierls (1907–1995) was a German-born theoretical physicist whose work helped shape modern solid‑state physics and the development of nuclear weapons. Born in Berlin to an assimilated Jewish family, he showed an early interest in science and engineering. He studied physics at several leading German universities, learning under some of the most influential figures of the era, including Arnold Sommerfeld, Werner Heisenberg, Wolfgang Pauli, and Niels Bohr. The rise of Nazism in the early 1930s forced Peierls, like many Jewish scientists, to leave Germany. He moved first to Zurich and then to Britain, where he eventually built his career and became a British citizen in 1940.

Peierls made major contributions to quantum theory and solid‑state physics, including work on electronic band structure, lattice vibrations, and what later became known as the Peierls transition. However, he is perhaps best known for his role in the early development of nuclear weapons. In 1940, together with Otto Frisch, he wrote the Frisch–Peierls memorandum, the first technical document to show that an atomic bomb was feasible using only a small amount of uranium‑235. This memorandum directly influenced the creation of the British Tube Alloys project and later the American Manhattan Project. During the war, Peierls worked at Los Alamos, where he led the implosion theory group responsible for the design of the plutonium bomb.