This June, the Postal Service released a new stamp honoring Maria Goeppert Mayer, a Nobel Prize-winning physicist who worked at the U.S. Department of Energy’s Argonne National Laboratory in the 1940 and ‘50s. The year also marks the 20th anniversary of the founding of the Women in Science and Technology organization at Argonne.
Only the second woman to win the Nobel Prize in Physics, Goeppert Mayer was born in Germany in 1906. Her father was a professor of pediatrics, the sixth generation of professors in the family, which Maria—the only child—would one day carry on, though not until half a century later.
In school Goeppert excelled at math and physics. At the time she entered college in Germany, where she studied theoretical physics and quantum mechanics, just 10 percent of the students at the school were women.
While studying for her Ph.D. she met Joseph Mayer, an American student studying on a fellowship. The couple married and moved to the United States, where Joseph got a job with Johns Hopkins University; but nepotism rules prohibited more than one family member working in the same faculty. She had to “volunteer” to do research at the department, the first in a long string of unpaid volunteer positions she would take at several universities—all the while working alongside giants like Enrico Fermi and James Franck.
In 1946, Joseph Mayer was offered an appointment at the University of Chicago. Just nearby, Argonne National Laboratory had just been created as the first official national laboratory, and Maria was offered a regular appointment as a Senior Physicist—which she happily accepted. She split her time between Argonne and the University of Chicago’s Institute of Nuclear Physics (now the Enrico Fermi Institute).
While studying the abundance of elements, she noticed that nuclei of elements with specific numbers of neutrons or protons tended to be more abundant than others. Nuclei with the “magic numbers” of neutrons or protons—2, 8, 20, 28, 50, 82 and 126—are more stable, and thus appear more commonly in nature; no one knew why.
Physicists had already worked out a theory of how electrons move around the nucleus: in layers, or “shells”, based on their energies. But at the time most physicists thought that protons and neutrons inside the nucleus, called nucleons, did not form shells the way electrons do.
Goeppert Mayer, inspired by a conversation with Enrico Fermi, set about proving that nucleons do form shells, and they exhibit individual particle motion. Much like the Earth spins around on its own axis while also rotating around the Sun at the same time, nucleons spin on their own axes while also moving in a larger orbit. This phenomenon is called spin-orbit coupling, and it allowed scientists to explain previously baffling observations about the atom, such as binding energies and rates of beta decay.
Magic numbers result when a particular shell is “full” of nucleons. With a full shell, the atom is less likely to interact with other nucleons, and is thus more stable.
For this work, Goeppert Mayer shared one-half of the 1963 Nobel Prize in Physics with J. Hans Daniel Jansen. In 1960, she was finally offered a full professorship at the University of California at San Diego, where she and her husband both became professors. She died in 1972.
A plaque honors her at the entrance of Argonne’s Physics Building, where she kept her office during her 15 years at Argonne.
Argonne’s branch of the Women in Science and Technology program formed in 1991, 30 years after Goeppert Mayer left, to bring together the female community at the lab. The group held Friday lunches to talk about issues facing women scientists and engineers and soon expanded into community outreach. Every year, the Introduce a Girl to Engineering Day program brings middle school-aged girls to the lab to meet women researchers and participate in hands-on science experiments. For high schoolers, the Science Careers in Search of Women program offers hundreds of high school girls a chance to come to the lab to learn more about careers in science and technology.
“Maria Goeppert Mayer challenged everyone,” said Kawtar Hafidi, an Argonne physicist who heads the WIST program and works in the same building that Goeppert Mayer did. “She showed everyone that we have to give a chance to more women—we need the best minds in science, whether male or female. The story doesn’t end with Maria Goeppert Mayer.”
The first-class postage stamp is part of a series called “American Scientists.”