Jewish culture and many Jewish scientists had a significant role in the project. The theoretical physicist Robert Oppenheimer, often considered as the ""father of the atomic bomb"", was chosen to direct the Manhattan Project at Los Alamos National Laboratory in 1942. The physicist Leó Szilárd, that conceived the nuclear chain reaction; Edward Teller, ""the father of the hydrogen bomb"" and Stanislaw Ulam; Eugene Wigner contributed to theory of Atomic nucleus and Elementary particle; Hans Bethe whose work included Stellar nucleosynthesis and was head of the Theoretical Division at the secret Los Alamos laboratory; Richard Feynman, Niels Bohr, Victor Weisskopf and Joseph Rotblat.
Nuclear reactor lower than had previously been thought. The memorandum was a product of the MAUD Committee, which was working on the UK atomic bomb project, known as Tube Alloys, later to be subsumed within the Manhattan Project. Eventually, the first artificial nuclear reactor, Chicago Pile-1, was constructed at the University of Chicago, by a team led by Italian physicist Enrico Fermi, in late 1942. By this time, the program had been pressured for a year by U.S. entry into the war. The Chicago Pile achieved criticality on 2 December 1942 at 3:25 PM. The reactor support structure was made of wood,