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 .