Leó Szilárd (Hungarian: Szilárd Leó, February 11, 1898 – May 30, 1964 German: Spitz, Leo until age 2) was a Hungarian- born American physicist and inventor. He conceived the nuclear chain reaction in 1933, patented the idea of a nuclear reactor with Enrico Fermi, and in late 1939 wrote the letter for Albert Einsteins signature that resulted in the Manhattan Project that built the atomic bomb.
Chien-Shiung Wu was a Chinese-American physicist with expertise in the techniques of experimental physics and radioactivity. She worked on the Manhattan Project, helping to develop the process for separating uranium metal into the U-235 and U-238 isotopes by gaseous diffusion. Wu later performed the Wu Experiment, which contradicted the "Law of Conservation of Parity". Her honorary nicknames include the "First Lady of Physics", the "Chinese Marie Curie", and "Madame Wu".
Lise Meitner was an Austrian born physicist who studied radioactivity and nuclear physics. Her deepest motivation was to pursue truth through scientific investigation for the benefit of humanity/ she deserves credit for her formulation of the theory which led to an understanding of how to unlock the energy within the atom. She was one of the pioneers of the atomic energy age, but she refused to join the Manhattan Project because, given her moral convictions, she did not wish to work on a bomb.