(C) Daily Kos
This story was originally published by Daily Kos and is unaltered.
. . . . . . . . . .
Top Comments: Physicist Maria Goeppert Mayer [1]
['This Content Is Not Subject To Review Daily Kos Staff Prior To Publication.']
Date: 2025-03-23
Here at Top Comments we strive to nourish community by rounding up some of the site's best, funniest, most mojo'd & most informative commentary, and we depend on your help!! If you see a comment by another Kossack that deserves wider recognition, please send it either to topcomments at gmail or to the Top Comments group mailbox by 9:30pm Eastern. Please please please include a few words about why you sent it in as well as your user name (even if you think we know it already :-)), so we can credit you with the find!
Continuing a series on great women in science for Women’s History Month, today I will write about Maria Goeppert Mayer, a woman who actually did win the Nobel Prize in Physics, only the second, after Marie Curie. (There are now five such women.) She won it for her work creating the shell model of the atomic nucleus. I’ve been wanting to write about her for some years because her dissertation work (on another topic entirely) was foundational to my own dissertation work, but until now, I have procrastinated to learn anything about the shell model. I figured now was as good a time as any to take that step.
Maria Goeppert was born in Kattowitz in the Kingdom of Prussia (now Katowice, Poland). When she was four, her family moved to Göttingen where her father became a professor of pediatrics at the university. Her father also encouraged her to pursue an education and a career. She first entered the University of Göttingen in 1924 to study mathematics, but attending a lecture by Professor Max Born on quantum mechanics caused her to switch to physics. She completed her doctorate in 1930, married Joseph Mayer, an American and a physical chemist, and the couple then moved to Baltimore, Maryland, where Joseph became a professor at Johns Hopkins University. Like many women with advanced degrees in this period, Maria was unemployed. However, she was given a desk at the university where she continued to pursue her own research without pay. Mayer later moved to Columbia University, but again, while Maria was allowed to pursue her own research, she had no salary. When the family moved to the University of Chicago in 1946, Goeppert Mayer finally obtained paid employment, half-time at the university’s Institute for Nuclear Studies, and half-time at nearby Argonne National Laboratory.
It was while in Chicago that she first considered the problem of the structure of nuclei, first concentrating on the masses of the elements and their isotopes. Atomic nuclei consist of positively charged protons and electrically neutral neutrons, particles both much heavier than the electrons that orbit the nucleus; each isotope is classified according to how many protons and neutrons each contains. Interestingly, if, for a particular isotope, you take the standard masses of the proton and the neutron, and add up the masses of all the particles that make up that particular isotope, you will get a mass that’s larger than the experimentally measured mass. The difference between the mass of a nucleus and the masses of the particles that make up that nucleus is called the mass defect. It is caused by the strong nuclear force, the force that keeps all of those particles together despite the strong repulsive force between the like charged protons. The strong force is so strong that the reduction of the energy on drawing these particles together reduces the nuclear mass (over those of the sums of the individual particles) by a measurable amount (E=mc2). The larger the mass defect, the greater the lowering of the energy, and the more stable the isotope. Goeppert Mayer and others studied these numbers looking for patterns, and found that certain numbers of protons or neutrons present in the nucleus made the nucleus more stable. Because no one knew what was behind this pattern, these were dubbed magic numbers: 2, 8, 20, 28, 50, 82, and 126.
By this time, of course, the theory of atomic structure had provided a broad explanation for the chemical behavior of the elements according to the arrangement of the electrons in an atom. There is a group of elements called the noble gases which do not react with other elements, or only react under extreme conditions. According to electronic structure theory, this behavior is due to the fact that all the noble gases have orbital shells completely filled by the atom’s electrons, which grants stability to the bare atoms. The analogy between the numbers of electrons designated for filled electronic shells in atoms, and the magic numbers for protons and neutrons in atomic nuclei, suggested the perhaps these magic numbers correspond to the filling of particle shells within the nucleus.
There is no real reason to expect this, as the environment within the nucleus is very different from that of the electrons orbiting it. The orbital states of the electrons are defined by the their electrical attraction to the positively charged nucleus, as an essentially imposed central force, but the inside of the nucleus is a jumble of particles roiling around each other, each particle attracted in some way to its neighbors. It is amazing that a chaotic environment like that could be found to have an order similar in nature to that of the electrons.
Applying simplifications, and identifying the pertinent quantum numbers for the designation of internal states of the nucleus, Goeppert Mayer was able to find groups of states, comparable to electronic orbitals, that gave rise to the observed magic numbers. Further, her theory could be used to predict what new isotopes ought to be stable. As she was submitting her first paper on the shell model, in 1948, she discovered that another researcher, Hans Jensen, had come up with the same result independently. Jensen and Goeppert Mayer became friends and collaborators, and shared the 1963 Nobel Prize for the shell model of the nucleus.
Goeppert Mayer was finally appointed to a full professorship at the University of California at San Diego in 1960, but she suffered a stroke shortly after and never fully recovered. She died in 1972.
Years later, I went off to graduate school and became interested in what was then a new technique called multiphoton spectroscopy. Spectroscopy is the study of the interaction of light and matter. One of the most important spectroscopic phenomena is light absorption, where an atom or molecule absorbs a photon of light which causes an electron to jump from a low energy state to a higher energy state, where the difference in the energies of the state is exactly equal to the energy of the photon. Most light absorption is of this nature, where just one photon is absorbed, and transition probability is proportional to the intensity of light. However, with the advent of high-intensity lasers, it was discovered that a transition could be induced using two photons, simultaneously absorbed, each of half the energy required to reach the upper state. The transition probability for simultaneous two-photon absorption is proportional to the square of the light intensity, and so this phenomenon requires intense laser light to observe it. The phenomenon of two-photon absorption was the topic of Maria Goeppert Mayer’s Ph. D. dissertation. She predicted theoretically that this phenomenon was possible three decades before the technology required to observe it existed.
Comments are below the fold.
Top Comments (March 21-23, 2024):
From thesphynx:
G2geek's excellent explanation of why we need to discourage vandalism and violent protests against Tesla and generally. From Bill Addis’s recommended post 80 Teslas at once vandalized at Canadian Showroom.
From FishOutofWater:
Sometimes there is an absolute gem under a dogpile of comments. EagleOfFreedom's comment shines like a ruby. From Chuck Walter’s recommended post What you don’t want to hear. I will be dogpiled.
Highlighted by HopefulEnigma90:
Highlighted by A Noah Count:
This comment by Perlinator in KeithDB’s recommended post Trump Claims Not To have Signed Alien Enemies Act Deportation Document. So Who Did?
Highlighted by wakingupmagenta:
This comment by patrick ford in Alex Samuels’ front page post What the hell is Gavin Newsom trying to do?
Top Mojo (March 20, 2024):
Top Mojo is courtesy of mik! Click here for more on how Top Mojo works.
Top Mojo (March 21, 2024):
Top Mojo (March 22, 2024):
[END]
---
[1] Url:
https://www.dailykos.com/stories/2025/3/23/2311814/-Top-Comments-Physicist-Maria-Goeppert-Mayer?pm_campaign=front_page&pm_source=latest_community&pm_medium=web
Published and (C) by Daily Kos
Content appears here under this condition or license: Site content may be used for any purpose without permission unless otherwise specified.
via Magical.Fish Gopher News Feeds:
gopher://magical.fish/1/feeds/news/dailykos/
