Original: Enrico Fermi (29 September 1901 – 28 November 1954)  was an Italian physicist most noted for his work on the development of the first nuclear reactor, and for his contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics.
Simplified: Enrico Fermi (September 29, 1901 – November 28, 1954) was an Italian physicist who worked on the first nuclear reactor and helped make quantum theory.