Maria Goeppert Mayer
Awarded the Nobel Prize in Physics 1963 for discoveries concerning nuclear shell structure. She shared the prize with Eugene Wigner and Hans Jensen.Of the 193 individuals awarded the Nobel Prize in Physics between 1901 and 2012, only two are women: Maria Goeppert Mayer and Marie Curie.
Maria Goeppert Mayer was often asked why girls needed to study science. Sometimes she answered with a counter question: “Do girls only have to learn how to read just to study cook books?”
Maria was the only child, descending on her father's side from six generations of professors. Maria was determined to become the seventh professor in her family. In the early 1930s, she passed her doctor’s degree in theoretical physics and married the American physicist Joseph Mayer, who said : ”She was a terrible flirt – but lovely and brighter than any other girl I had ever met.”
At the end of World War II (1939-1945), Maria attended the U.S. atomic bomb project and in 1948 she began with research on how atomic nuclei are built up, including the so-called "magic numbers" that had long puzzled scientists. After only a year, in 1949, she finds the solution!
Elements always have a nuclear charge, that is a specific number of protons, positively charged particles in the atom's nucleus. The number of neutrons, non-charged particles in the nucleus, can vary however.
All these variations of the same element but with different numbers of neutrons are called isotopes. A stable isotope does not decompose with time, but retains the number of protons and neutrons intact.
In earlier experiments one had found that stable nuclei either have exactly 2, 8, 20, 28, 50, 82 and 126 protons - or exactly as many neutrons. These numbers were called the "magic numbers". But what made nuclei with “magic numbers” so stable?
“It was like a jigsaw puzzle. I had many pieces (not only the “magic numbers”), so I could see a picture began to emerge. I felt that if I had only one more piece of the puzzle, everything would fall into place. I found the piece, and everything became clear.”
The last piece in the puzzle was the discovery that protons and neutrons are spinning along orbits inside the atomic nucleus - in the same manner that earth spins around its own axis while moving in an orbit around the sun. The orbits in the atomic nuclei are like several shells, much like an onion with many shells but nothing in the center, Maria explained.
The first orbit, or shell, in an isotope should for the best stability have 2 particles, the second orbit 8 particles, the third orbit 20, the fifth 28, the sixth 50 and so on. The "magic numbers" would represent the points at which the various shells would be complete.
Maria’s idea to liken the atomic nuclei with an onion made Wolfgang Pauli, also awarded a Nobel Prize in Physics, give her the nickname “The Onion Madonna”.
Maria’s contribution to nuclear physics is mathematics that connect the “magic numbers” in stable isotopes to a structural model of the nucleus. For example, this helps to predict which isotopes are best suited for production of nuclear energy.