(Inside Science) -- The Manhattan Project wasn’t only an endeavor of white men. Women and people of color played pivotal roles, despite discrimination and systematic barriers. Many members of these marginalized groups held nonresearch positions such as clerical work, construction, and maintaining and operating facilities. Some became renowned scientists -- both during and after World War II.
There is no record of any Black employees working at Los Alamos during the war. Other sites such as Oak Ridge only hired Black workers for low-level positions and forced them to live under far worse conditions than their white counterparts. Only a few Black people were ever hired to work on the Manhattan Project as scientists or technicians. Several other racial groups were also conspicuously absent.
White women had more opportunities. At that time, most research institutions had nepotism rules that forbade hiring both members of a married couple. Scientists often married other scientists, and the husband’s career almost always took precedence, so such rules were a major barrier keeping women out of academia. But faced with labor shortages and an urgent need for scientific talent, many Manhattan Project sites actively recruited female scientists along with their husbands, resulting in a female scientific labor force hundreds strong.
After the war, the diverse Manhattan Project alumni went on to many and varied achievements, from making Nobel Prize-winning discoveries about the nature of atoms to developing new medicines for deadly diseases.
Isabella Karle was a chemist who worked to purify plutonium at the University of Chicago’s Metallurgical Laboratory as part of the Manhattan Project. Karle and her husband Jerome left the Met Lab before the war was over to conduct their own research.
Karle invented and built an improved electron diffraction apparatus for identifying the molecular structure of gaseous chemicals. But not all molecules could be vaporized. To analyze chemicals in solid states, Karle developed improved methods of X-ray crystallography. Her methods confirmed her husband’s theoretical work and solved the structures of biological molecules such as proteins -- an essential part of drug development.
When Karle’s husband won the 1985 Nobel Prize in chemistry for work they did together, he was upset that she was not included. She had to convince him to accept the prize, according to her New York Times obituary. But Karle won many awards of her own, including the National Medal of Science.
Image Credits: Dan Dry and the University of Chicago Magazine (used with permission)
J. Ernest Wilkins Jr.
Mathematics prodigy J. Ernest Wilkins Jr. started college at age 13 and earned a doctorate from the University of Chicago at age 19. He was one of the few Black scientists to work on the Manhattan Project, studying fissionable materials at the Metallurgical Laboratory. He wasn’t told the purpose of his research until after the atomic bomb was dropped on Hiroshima, Japan.
When the rest of his team was transferred to Oak Ridge, Jim Crow laws prevented Wilkins Jr. from joining them, so he took a post with Eugene Wigner working on nuclear reactors. After the war, he conducted research on optics and nuclear energy, and developed mathematical models and shielding techniques for gamma radiation.
Later, Wilkins Jr. launched Howard University’s mathematics doctoral program. He received many awards and honors, including the U.S. Army’s Outstanding Civilian Service Medal. He also served as president of the American Nuclear Society and as a council member for the American Mathematical Society.
Image Credits: Courtesy of the Atomic Heritage Foundation and the National Museum of Nuclear Science & History (used with permission)
Floy Agnes Lee
Floy Agnes "Aggie" Lee was the daughter of a Pueblo Indian man and a German American woman. She learned to fly planes in college in hopes of joining the Women’s Airforce Service Pilots. After graduating with a biology degree, she took a job at the Los Alamos drawing blood from researchers for testing. She witnessed the effects of radiation poisoning firsthand when two of the researchers she worked with were exposed during an accident.
She became friends and tennis partners with Enrico Fermi. His identity was kept secret from her for security reasons, and she was astonished when she finally learned who he was. "I said, 'Oh, I can’t believe that,'" she recalled in an interview for Voices of the Manhattan Project. "I was beating him in tennis every time."
After the war, she worked at Argonne National Lab and earned a doctorate in zoology. She then spent many years studying the effects of radiation on living cells and chromosomes. She advocated for science education and helped found the American Indian Science and Engineering Society.
Legendary physicist Chien-Shiung Wu was nicknamed "the first lady of physics" and "the queen of nuclear research." She emigrated to the U.S. from China in 1936 and completed her doctorate at the University of California, Berkeley. In 1944 she went to Columbia University in New York to work on uranium enrichment for the Manhattan Project. Her contributions included improving the design for Geiger counters.
When the first large-scale plutonium reactor at Hanford shut down shortly after researchers tried to fire it up, Wu traced the problem to the presence of the xenon isotope Xe-135.
Wu later made many important advances in nuclear physics and even contributed to the understanding of sickle-cell anemia. She devised the experiment that disproved a supposed natural law known as conservation of parity, confirming theoretical work by Tsung Dao Lee and Chen Ning Yang. Lee and Yang received a Nobel Prize for the discovery, but Wu’s role was not recognized. She did win many other honors, including the National Medal of Science, and became the first woman to serve as president of the American Physical Society.
Image Credits: Courtesy of the North Little Rock History Commission (used with permission)
Samuel Massie Jr.
Samuel Massie Jr. faced many hurdles of discrimination, but he didn’t let it stop him from making lifesaving discoveries. He studied chemistry in part because he wanted to find a cure for his father’s asthma, and during his career, he worked on treatments for malaria, herpes, gonorrhea, meningitis, schizophrenia and cancer. He also developed foams to protect people from nerve gas.
When the University of Arkansas denied him admittance as an undergraduate due to his race, he attended Arkansas Agricultural, Mechanical & Normal College, graduating summa cum laude at age 18. Iowa State University accepted him as a doctoral student but forbade him from living on campus or using the same lab as white students.
While Massie was working on his doctorate, a member of the draft board in Arkansas refused to renew his draft deferment because of his race. Massie asked for help from Henry Gilman, who recruited him into the Manhattan Project converting uranium isotopes into usable liquids.
After the war, Massie Jr. became the first Black president of the Oklahoma Academy of Science and the first Black professor at the U.S. Naval Academy, and later won an award from the White House.
Maria Goeppert Mayer
Maria Goeppert Mayer was descended from six consecutive generations of university professors; she made it seven. She emigrated to the U.S. from Germany after completing her doctorate in quantum mechanics in 1930.
She was forced to take unpaid research positions for years due to nepotism rules that prevented her from being hired by the same institutions where her husband, chemist Joseph Edward Mayer, worked. That finally changed in 1942 when Mayer accepted a part-time job at Columbia University working on the Manhattan Project. She soon became the leader of a team of 20 researchers and technicians working to separate uranium isotopes.
After the bombs dropped in Japan, she worked part time at the University of Chicago, continuing research she started with Edward Teller during the war. She also held a part-time position at Argonne National Laboratory. She finally became a full-time paid professor at the University of California, San Diego in 1960.
Mayer is most famous for her shell model of atomic nuclei, which explains why atoms with certain "magic numbers" of protons or neutrons are especially stable. The discovery earned her part of the 1963 Nobel Prize in physics.
Editor’s Note: A previous version of this article incorrectly stated that all of the Black scientists on the Manhattan project were men. Carolyn Beatrice Parker, a Black woman and physicist, also worked on the Manhattan Project. We regret the error and honor her achievements.
Inside Science would like to thank Alex Wellerstein, Vincent Intondi and Ruth Howes for providing information used in this article. For further reading about the people featured and other women and people of color who worked on the Manhattan Project, please see:
"Their Day in the Sun" by Ruth H. Howes & Caroline L. Herzenberg
The Atomic Heritage Foundation and Voices of the Manhattan Project
The Maria Goeppert Mayer biographical memoir at the National Academy of Sciences
The obituary for Samuel Massie by Yvonne Shinhoster Lamb in the Washington Post
The obituary of J. Ernest Wilkins, Jr. by Ronald E. Mickens in Physics Today
The obituary of Isabella Karle by Kenneth Chang in the New York Times
The biography of Chien-Shiung Wu at the Manhattan Project National Historic Park
For more stories, videos and infographics related to Inside Science's coverage of the far-reaching ways that the Manhattan Project influenced science and society, visit our page: Seventy-Five Years After Trinity.