Weisskopf, a nuclear physicist who worked on the Manhattan Project
to build the first atomic bomb in World War II and later became an
ardent advocate of arms control, died on Monday at his home in
Newton, Mass. He was 93.
Dr. Weisskopf was one of the first physicists to warn of the
possible dangers of atomic research. In 1939, he and Leo Szilard,
another atomic physicist, recommended that physicists keep secret
their findings on nuclear fission instead of publishing them in
academic journals, out of fear that the information could help Nazi
scientists build atomic weapons.
In 1943, Dr. Weisskopf joined the Manhattan Project as associate
head of the theory division. In a lecture at the Massachusetts
Institute of Technology in 1991, he recounted the rationale for
dropping the bomb on Hiroshima in August 1945, that the destruction
needed to have a strong psychological effect on Japan.
The second bomb, dropped on Nagasaki three days later, was more
troubling to him.
"The second bomb I don't hesitate to call a crime," Dr. Weisskopf
told the audience at M.I.T. He also called the cold war "a
collective mental disease of mankind."
Early in his career, Dr. Weisskopf laid the groundwork for fixing
a fundamental flaw in applying quantum mechanics to
electromagnetism. After World War II, he furthered understanding of
how the nuclei of atoms behave.
"He really made so many contributions that it's hard to identify
any single one," said Dr. Robert L. Jaffe, director of the Center
for Theoretical Physics at M.I.T.
Dr. Weisskopf also lent his name and voice to political issues.
In letters and opinion pieces in newspapers, he repeatedly warned of
the dangers of nuclear war. Although he was of Jewish descent, he
was appointed by Pope Paul VI to the 70-member Pontifical Academy of
Sciences in 1975, and in 1981 he led a team of four scientists sent
by Pope John Paul II to talk to President Ronald Reagan about the
need to prohibit the use of nuclear weapons.
Victor Frederick Weisskopf was born Sept. 19, 1908, in Vienna. He
earned his doctorate in physics at the University of Göttingen in
Germany in 1931.
In postdoctoral studies at the University of Berlin, University
of Copenhagen, Cambridge University and the Institute of Technology
in Zurich, Dr. Weisskopf apprenticed with many great founding
physicists of quantum mechanics: Werner Heisenberg, Erwin
Schrödinger, Niels Bohr and Wolfgang Pauli.
In 1937, shortly before Germany absorbed Austria, Dr. Weisskopf
immigrated to the United States, landing a position at the
University of Rochester.
After the war, he became a professor at M.I.T. From 1961 to 1965,
he served as director-general of the CERN particle accelerator in
Switzerland before returning to M.I.T. He retired in 1974.
In the 1930's, he and Pauli wrote a paper applying quantum
mechanics to "spinless" particles, which they regarded as a
mathematical obscurity, because at that time all known particles
like protons, electrons and neutrons carried spin, or angular
momentum, like a spinning top. Only a few years later, such spinless
particles appeared in the high-energy collisions at particle
In the 1930's, Dr. Weisskopf tackled the application of quantum
mechanics to electromagnetic fields. At the time, physicists'
calculations were producing absurd answers: electrons were
infinitely massive and produced infinitely powerful electric
Dr. Weisskopf was among the first scientists to suggest a
mathematical technique to rein in the unruly equations, essentially
imagining that an infinitely large charge would induce a cloud of
"virtual particles" fluttering in and out of existence around it
that would nearly offset infinite charge.
"He was the first person to make significant progress in taming
the infinities of field theory," Dr. Jaffe said.
A decade later, the theory was completed by three physicists,
Sin-Itiro Tomonaga, Julian Schwinger and Richard Feynman. It won
them a Nobel Prize in 1965.
"He had done work at the frontiers of theoretical physics in the
1930's that perhaps was only partly successful because it was so far
ahead of its time," said Dr. Steven Weinberg, a professor of physics
at the University of Texas.
Dr. Weisskopf was a member of the National Academy of Sciences.
He was president of the American Physical Society in 1960-61 and
president of the American Academy of Arts and Sciences from 1976 to
His 1952 textbook, "Theoretical Nuclear Physics," written with
John M. Blatt, was the basic reference for the new field. He also
wrote essays for a public audience, including his memoir, "The Joy
of Insight: Passions of Physicist" (Basic Books, 1991).
His honors included the Medal of Science, the Wolf Prize in
Physics and the Enrico Fermi Award.
His first wife, Ellen, died in 1989.
He is survived by his second wife, Duscha; a son, Thomas E., of
Ann Arbor, Mich.; a daughter,
Karen Worth of Newton; and five grandchildren.
In the often competitive field of theoretical physics, Dr.
Weisskopf stood out as unusually generous and modest. Dr. Jaffe
recalled how in the mid-1970's, when he was a new faculty member at
M.I.T., he and his collaborators would talk to Dr. Weisskopf about
the theory they were developing to describing the behavior of
quarks, the constituent particles of protons and neutrons.
Dr. Jaffe said Dr. Weisskopf did not understand all the
complexities in the theory, but "he listened patiently" and provided
a crucial insight that helped them solve the problem. The
researchers added Dr. Weisskopf as an author to acknowledge his
"He tried to get us to take it off the paper," Dr. Jaffe said.
"He said, `The only thing I contributed to this paper was the
Dr. Weisskopf's name remained on the paper.