On July 17, 1945, a day after the U.S. tested the first atomic bomb, dozens of scientists involved with the Manhattan Project – which developed the world’s first nuclear weapons during World War II – signed a petition to President Truman written by their colleague Leo Szilárd, who had first proposed the idea of a nuclear chain reaction. The petition urged the president not to approve the use of atomic weapons without first offering Japan a chance to accept terms of surrender. 

The scientists hoped that the U.S. might hold a demonstration for Japanese officials so that they could observe the effects of the bomb on an uninhabited area in order to avoid civilian casualties. Unfortunately, the president didn’t read the petition before the U.S. dropped the bombs on Japan, devastating the cities of Hiroshima and Nagasaki. (Read more about cities destroyed by the U.S. in World War II.)

The Szilárd Petition, which was kept secret from the public and remained classified until 1961, was signed by over 70 scientists who had worked to create the bombs. Ten of these scientists were women. To determine the women scientists who worked on the atomic bomb and later opposed its use, 24/7 Tempo utilized information from the Atomic Heritage Foundation to generate a list of every woman who signed the petition.

These women scientists who opposed the use of atomic weapons included two chemists, a psychologist, a biologist, a computer (meaning someone who did calculations), a technician, and four research assistants. All of them worked at the University of Chicago’s Metallurgical Laboratory, dedicated to the study of a newly discovered element, plutonium, and site of the first-ever artificial nuclear reactor.

Click here to read more about 10 women who helped develop the A-bomb, then opposed its use

After the war, one of the leading woman scientists on the Manhattan Project, Kay Way, went further to voice her opposition by compiling a book of essays called “One World or None: A Report to the Public on the Full Meaning of the Atomic Bomb.” Leading scientists including Albert Einstein, Niels Bohr, and J. Robert Oppenheimer contributed essays to the book, which voiced concerns about the ethics of nuclear weapons. (The bombs dropped on Japan were some of the 18 deadliest weapons of all time.)