Goeppert-Mayer , Maria

(1906–1972) German–American physicist

Maria Goeppert was born at Kattowitz in Poland and educated at the University of Göttingen where she obtained her PhD in 1930. (She changed her name on marrying the physical chemist, Joseph Mayer.) Emigrating to America in 1931 she was employed at Johns Hopkins University, Baltimore (1931–39), Columbia University, New York (1939–46), and the Argonne National Laboratory (1946–60). Finally, in 1960 she took a post at the University of California, San Diego, at La Jolla.

In 1963 she was awarded the Nobel Prize for physics together with the German physicist Johannes Jensen (1907–1973) and Eugene P. Wigner for their work on nuclear shell theory. The shell theory of the nucleus is analogous to the shell model of the atom. The theory could help explain why some nuclei were particularly stable and possessed an unusual number of stable isotopes. In particular, in 1948, she argued that the so called ‘magic numbers’ – 2, 8, 20, 50, 82, and 126 – which are the numbers of either protons or neutrons in particularly stable nuclei, can be explained in this way. She supposed that the protons and neutrons are arranged in the nucleus in a series of nucleon shells. The magic numbers thus describe those nuclei in which certain key shells are complete. In this way helium (with 2 protons and 2 neutrons), oxygen (8 of each), calcium (20 of each), and the ten stable isotopes of tin with 50 protons all fit neatly into this pattern. Also significant was the fact that, in general, the more complex a nucleus becomes the less likely it is to be stable (although there are two complex stable nuclei, lead 208 and bismuth 209, both of which have the magic number of 126 neutrons).