American National Biography    

   

 

Mayer, Maria Gertrude Goeppert (28 June 1906-20 Feb. 1972),

physicist, was born in Kattowitz, Germany (now Katowice, Poland),

the daughter of Frederich Goeppert, a pediatrician, and Maria

Wolff. Maria Goeppert grew up in the university town of Gottingen,

Germany, where her father became a professor of pediatrics at

the University of Gottingen in 1910. With his encouragement,

she became interested in science and mathematics at an early

age and enrolled in the same university in 1924 to study mathematics. 

 

 Gottingen in the 1920s was one of the world's best universities,

boasting of such great mathematicians and physicists as David

Hilbert, Max Born, and James Franck. In 1927 Maria Goeppert switched

from mathematics to theoretical physics after attending Born's

seminars. With Born she studied the exciting new quantum mechanics

that was being developed by Werner Heisenberg and Born himself.

She spent one term in 1928 in England at Cambridge University,

where she not only improved her English but also attended lectures

by the great experimental physicist Ernest Rutherford. In 1930

she completed her dissertation under Born on a theory of the

double photon process--the probability of the emission of two

light quanta in a single atomic transition--and received her

Ph.D. from Gottingen. The same year she married Joseph E. Mayer,

an American chemical physicist who had come to work with Franck,

and together they moved to Baltimore, where he accepted an appointment

in chemistry at the Johns Hopkins University. She became a U.S.

citizen in 1933 and gave birth to two children. 

 

 Because of nepotism rules and the traditional emphasis on experimental

physics at American universities, Maria Mayer, a theoretician,

received only a nominal appointment as a "volunteer associate"

at Johns Hopkins. Nevertheless, with support from her husband

and other faculty members, especially theoretical physicist Karl

Herzfeld, she did engage in active research on applying quantum

mechanics to chemical physics, the solid state, and other subjects.

For several summers she also went back to Gottingen to work with

Born. Later when Franck joined Johns Hopkins, and Edward Teller,

another friend from the Gottingen days, came to George Washington

University in nearby Washington, D.C. she renewed collaboration

with them, too. At Johns Hopkins, she also had her first graduate

student, Robert G. Sachs, with whom she studied the new nuclear

physics and published a joint paper on the subject in 1938. She

impressed her students with both her ability to use mathematics

to solve physical problems quickly and her "well organized, very

technical, and highly condensed" (Sachs, pp. 316-17) occasional

graduate lectures. 

 

 In 1940 the Mayers went to Columbia University, where Joseph

Mayer became associate professor of chemistry. The same year

they completed a book, Statistical Mechanics. Maria Mayer received

no offer from Columbia, although Harold Urey, head of the chemistry

department, asked her to give some classes as a lecturer. Mayer

continued her research in physics, now with the support and guidance

of Enrico Fermi, a pioneer in modern physics who was then at

Columbia. At Fermi's suggestion, Mayer fruitfully investigated

the chemical properties of several transuranium elements through

the use of quantum mechanics. 

 

 Like many other American women, Mayer was employed in a real

job for the first time during World War II. In December 1941

she began to teach, part time, a science course at Sarah Lawrence

College in Bronxville, near New York. Then in the spring of 1942

she took another part-time job in Urey's Substitute Alloy Materials

Laboratory at Columbia, which, as part of the Manhattan Project,

was aimed at separating uranium 235 from natural uranium for

the making of the atomic bomb. In this work she made ample use

of her expertise in chemical physics. She first explored, with

a team of scientists, the possibility of separating isotopes

such as U-235 by photochemical reactions, which proved not very

promising (at least not until the invention of the laser in the

1960s). She then studied the thermodynamic properties of uranium

hexafluoride for the gaseous diffusion and photochemical separation

methods of making U-235. During the war, she also worked with

Teller on problems related to the development of the thermonuclear

weapon, entailing a stay of several months in Los Alamos, New Mexico. 

 

 In February 1946 the Mayers moved again, to the University of

Chicago, where Joseph Mayer assumed professorships in both the

chemistry department and the new Institute for Nuclear Studies.

Nepotism rules once again prevented a regular position for Maria

Mayer; she became a voluntary associate professor of physics

in the institute. The position allowed her to participate in

all university activities, including lecturing to classes and

supervising graduate students. With the arrival of Fermi, Franck,

Urey, Teller, Willard Libby, the Mayers, and other prominent

scientists, Chicago soon became a center of nuclear physics and

chemistry in the world. During this period, Maria Mayer continued

to work with Teller on the thermonuclear project, first at the

Metallurgical Laboratory of the Manhattan Project, and then at

its successor, the Argonne National Laboratory, which the University

of Chicago managed for the new Atomic Energy Commission. When

Sachs came to head Argonne's theoretical physics division in

1946, he offered his former professor a regular, albeit half-time,

paid job as a senior physicist. In this especially stimulating

environment, Maria Mayer began to study nuclear physics seriously

and soon made her own major contribution, the nuclear shell model. 

 

 Mayer first became interested in the shell structure of nuclei

when she collaborated with Teller on a cosmological model of

the origin of the chemical elements. The project involved compiling

a list of available isotopes--atoms with the same number of protons

but differing numbers of neutrons in their nuclei--of the elements

and their "abundances." A higher abundance of an isotope indicated

that it had a more stable nuclear structure than others. In collecting

and analyzing the data, Mayer found a pattern in that nuclei

with "magic numbers" of 2, 8, 20, 28, 50, 82, or 126 neutrons

or protons were unusually stable. It immediately led her to think

of a shell structure of the nucleus analogous to the shell structure

of the atom itself. 

 

 The shell model of the atom portrays it as a planetary system,

consisting of a nucleus, positively charged, and with one or

more electrons, negatively charged and spinning around the nucleus

and on their own axes, like the planets around the sun. According

to quantum mechanics, there are only certain discrete energy

levels (shells or orbits) for an electron to occupy, and only

certain numbers of electrons can occupy each level. If an atom

fills each of its shells with the maximum number of electrons,

it becomes stable. This is the case with the inert gases, whose

atomic numbers (numbers of electrons) are 2, 10, 18, 36, 54,

and 86. In studying the nuclei, several other physicists before

Mayer had also speculated about a shell structure on similar

but less firm evidence. Most nuclear physicists, however, discounted

the shell model on the ground that the interactions among protons

and neutrons within the small nucleus are so strong that the

internal structure of the nucleus must be radically different

from that of the atom. The prevailing liquid-drop model of the

nucleus treated it as a homogeneous mass of materials, rather

than a collection of discrete particles. 

 

 A near novice in nuclear physics, Mayer nevertheless persisted

in constructing a shell model, through the use of quantum mechanics,

to make sense of her magic numbers. In this, she was aided by

her husband and, above all, Fermi. Her various calculations failed

to yield the desired results, however, until one legendary moment

when Fermi, leaving Mayer's office after a long discussion on

the subject to take a phone call, asked her the crucial question,

"Is there any indication of spin-orbit coupling?" "When he said

it," Mayer later recalled, "it all fell into place." Familiar

with electrons' spin-orbit coupling in her earlier research and

proficient in the mathematics of quantum mechanics, Mayer proceeded

to calculate how protons or neutrons spinning and orbiting in

different directions could have different energy levels and thereby

allow, in a manner analogous to the atomic structure, only the

magic numbers of them to occupy each level. 

 

 Mayer's spin-orbit-coupling shell model of nuclear structure

soon gained acceptance by the scientific community, partly because

it was independently and simultaneously discovered by a team

led by Hans D. Jensen at the University of Heidelberg in Germany.

Mayer later collaborated with Jensen in writing a book, Elementary

Theory of Nuclear Shell Structure (1955), to explain their work.

In 1963 Mayer and Jensen were awarded the Nobel Prize in physics

(shared with Eugene P. Wigner) for their theory. (Wigner earlier

had worked on the nuclear structure, but he won the prize mainly

for his application of group theory in particle physics.) She

was the second woman in history, after Marie Curie in 1903, to win that prize. 

 

 In 1960 Maria and Joseph Mayer made their last move, this time

to the University of California at San Diego, where she became,

for the first time, a full-time professor in physics and he a

professor in chemistry. Unfortunately, she suffered a stroke

shortly after arriving in San Diego and had health problems thereafter,

although she continued to teach and conduct research until her

death. She died in San Diego. 

 

 Maria Goeppert Mayer, through her scientific research, especially

her shell model of nuclear structure, made a great contribution

to human understanding of nature and, by her example, served

to inspire many women in science.    

 

 

 Bibliography

 

 Maria Goeppert Mayer's papers are deposited in the Special Collections

of the Library of the University of California, San Diego. Robert

G. Sachs, "Maria Goeppert Mayer," National Academy of Sciences

of the United States of America Biographical Memoirs 50 (1979):

311-28, provides useful biographical information and a bibliography.

Joan Dash, A Life of One's Own: Three Gifted Women and the Men

They Married (1973), accounts Mayer's personal and family life

based on interviews with Maria and Joseph Mayer. Karen E. Johnson,

"Maria Goeppert Mayer: Atoms, Molecules and Nuclear Shells,"

Physics Today 39 (Sept. 1986): 44-49, traces Mayer's scientific

contributions and her route to the nuclear shell model. An obituary

is in the New York Times, 22 Feb. 1972.  

 

 Zuoyue Wang

 

   

 Online Resources

 

   The Nobel Prize in Physics 1963

http://www.nobel.se/physics/laureates/1963/

 From the Nobel e-Museum, the Official Web Site of The Nobel Foundation. 

 

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   Citation:

 Zuoyue Wang. "Mayer, Maria Gertrude Goeppert";

http://www.anb.org/articles/13/13-01078.html;

American National Biography Online Feb. 2000.

Access Date: Tue Feb 18 16:09:09 2003

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