Maria Goeppert Mayer was one of the most consequential theoretical physicists of the twentieth century, and one of the most under-recognized for much of her working life. She shared the 1963 Nobel Prize in Physics for the nuclear shell model, becoming only the second woman to win that prize after Marie Curie sixty years earlier. For decades before that recognition, she did original research without a paid faculty appointment, following her husband from university to university under nepotism rules that treated a professor’s wife as ineligible for a real job.
She was born Maria Gertrud Käte Göppert on June 28, 1906, in Kattowitz, then in German Upper Silesia and now Katowice, Poland. She was the only child of Friedrich Göppert, a pediatrician and the seventh generation of university professors in his family, and Maria Wolff Göppert, a teacher of French and piano. In 1910 the family moved to Göttingen so that her father could take a chair in pediatrics. Göttingen was then one of the world’s great centers of mathematics and the new quantum theory. David Hilbert was a neighbor. Max Born and James Franck became family friends. The expectation that Maria would go to university was never really debated; her father told her not to grow up to be “just a woman,” meaning a housewife.
There was no public school in Göttingen that prepared girls for the Abitur, the university entrance exam. She attended a small private school run by suffragettes. When inflation closed it, the teachers kept tutoring. In 1924 she sat the exam in Hannover as an external candidate, facing examiners she had never met, and passed. That spring she entered the University of Göttingen intending to become a mathematician. Quantum mechanics was exploding around her. After a term at Cambridge, where she learned English, she shifted to theoretical physics under Born. Her 1930 doctoral thesis treated two-photon processes—the simultaneous absorption or emission of two light quanta by an atom. The calculation was so far ahead of experiment that it was confirmed only after the laser existed, in 1961. The unit used today for two-photon absorption cross sections is the Goeppert-Mayer, or GM. Her examining committee included three future or already-crowned Nobel laureates: Born, Franck, and Adolf Windaus.
Just before the doctorate she married Joseph Edward Mayer, an American chemist working with Franck who had boarded in her mother’s house. They sailed for the United States. Johns Hopkins hired him; anti-nepotism rules barred her from a faculty post. She worked as a volunteer associate, taught, handled German correspondence, and published. In 1935 she produced an important paper on double beta decay. With Karl Herzfeld and her husband she studied the spectra of organic molecules. She became a U.S. citizen in 1933. Their children, Maria Ann and Peter Conrad, were born in Baltimore. When Joseph Mayer left Johns Hopkins in 1939, they moved to Columbia. Again she had no paid professorship. She lectured at Sarah Lawrence and, after the United States entered the war, joined the Manhattan Project’s SAM Laboratory under Harold Urey, working on isotope separation and photochemical methods that did not become the main production route. Later she spent time with Edward Teller on opacity calculations relevant to thermonuclear weapons. She later said she was relieved that her particular line of work had not succeeded.
The move to Chicago in 1946 changed the professional climate if not immediately the paycheck. The University of Chicago made her a volunteer associate professor in the Institute for Nuclear Studies; Argonne National Laboratory hired her as a senior physicist. She learned nuclear physics in conversation with Fermi and Teller. The empirical puzzle was the “magic numbers”—2, 8, 20, 28, 50, 82, 126—the numbers of protons or neutrons that made nuclei unusually stable. Existing models could not explain the higher ones. In 1948 she assembled the experimental evidence that closed shells really existed. The missing piece was strong spin-orbit coupling: a nucleon’s energy depends on whether its spin is aligned with or against its orbital motion. Fermi asked her whether there was evidence for that coupling. She later said that when he asked, “it all fell into place.” She finished the calculation that night. Independently, J. Hans D. Jensen and colleagues in Germany reached the same conclusion. Their papers appeared in 1949. The two groups later became collaborators and co-authored Elementary Theory of Nuclear Shell Structure (1955). The model treated the nucleus as a series of filled orbital shells, analogous to electron shells in atoms, and accounted for spins, magnetic moments, and isomerism across a wide range of nuclei.
Chicago finally gave her a regular full professorship in 1959. In 1960 she and Joseph Mayer moved to the new University of California campus at San Diego, where she received her first full-time paid physics professorship at the age of fifty-three. Soon afterward she suffered a stroke. She continued to teach and work. In 1963 she shared the Nobel Prize in Physics with Jensen “for their discoveries concerning nuclear shell structure”; Eugene Wigner received the other half for unrelated work on symmetries. A local paper headlined the news “S.D. Mother Wins Nobel Prize.” She told students that winning the prize was not half as exciting as doing the work. She was elected to the National Academy of Sciences in 1956 and received honorary degrees from several colleges.
Health problems continued. She died of a heart attack in San Diego on February 20, 1972, at sixty-five. By then the shell model was a foundation of nuclear physics, still used to interpret stability, magic nuclei, and the limits of the periodic table. Two-photon absorption, once a purely theoretical curiosity in her thesis, became central to multiphoton microscopy and nonlinear optics. The American Physical Society established the Maria Goeppert Mayer Award for early-career women physicists. Argonne and UC San Diego named awards and buildings for her. A crater on Venus bears her name. She appears on a 2011 U.S. postage stamp.
Her career is often told as a story of barriers, and the barriers were real: unpaid labor, trailing-spouse status, newspapers that defined her first as a mother. It is also a story of stubborn intellectual independence. She worked “just for the fun of doing physics,” as she put it, in the same Göttingen tradition that had produced the quantum theory itself. She liked to describe theory as puzzle-solving, but of puzzles set by nature rather than by human ingenuity. The nuclear shell model was that kind of puzzle. Once the last piece—spin-orbit coupling—clicked, the pattern of stability that had looked arbitrary became a consequence of how nucleons occupy orbits. That clarity, achieved while she still lacked the formal rank her work deserved, is why her name remains attached both to a unit of nonlinear optics and to one of the central organizing ideas of nuclear structure.