John Archibald Wheeler

John Archibald Wheeler - Quick Facts

Profile Overview of John Archibald Wheeler

John Archibald Wheeler (July 9, 1911 – April 13, 2008) was an American theoretical physicist. He was largely responsible for reviving interest in general relativity in the United States after World War II. Wheeler also worked with Niels Bohr to explain the basic principles of nuclear fission. Together with Gregory Breit, Wheeler explored positron-electron pair production from the collision of two photons, now known as the Breit–Wheeler process. He is known for popularizing the term "black hole" to describe the gravitationally completely collapsed objects predicted by general relativity. He also coined "quantum foam", "neutron moderator", "wormhole" and "it from bit", and hypothesized the "one-electron universe". Stephen Hawking called Wheeler the "hero of the black hole story".

This profile of John Archibald Wheeler covers Early Life and Family Background, Early Career and Breakthrough, Manhattan Project, Hydrogen bomb and Career and Rise to Fame.

At 21, Wheeler earned his doctorate at Johns Hopkins University under the supervision of Karl Herzfeld. He studied under Breit and Bohr on a National Research Council fellowship. In 1939 he collaborated with Bohr on a series of papers using the liquid drop model to explain the mechanism of fission. During World War II, he worked with the Manhattan Project's Metallurgical Laboratory in Chicago, where he helped design nuclear reactors, and then at the Hanford Site in Richland, Washington, where he helped DuPont build them. He returned to Princeton after the war but returned to government service to help design and build the hydrogen bomb in the early 1950s. He and Edward Teller were the main civilian proponents of thermonuclear weapons.

For most of his career, Wheeler was a professor of physics at Princeton University, which he joined in 1938, remaining until 1976. At Princeton he supervised 46 PhD students, more than any other physics professor.

Wheeler left Princeton at the age of 65. He was appointed director of the Center for Theoretical Physics at the University of Texas at Austin in 1976 and remained in the position until 1986, when he retired and became a professor emeritus. With Kip Thorne and Charles Misner, he coauthored the general relativity textbook Gravitation.

Early Life and Family Background of John Archibald Wheeler

Wheeler was born in Jacksonville, Florida, on July 9, 1911, to librarians Joseph L. Wheeler and Mabel Archibald (Archie) Wheeler. He was the oldest of four children. His brother Joseph earned a PhD from Brown University and a Master of Library Science from Columbia University. His brother Robert earned a PhD in geology from Harvard University and worked as a geologist for oil companies and several colleges. His sister Mary studied library science at the University of Denver and became a librarian. They grew up in Youngstown, Ohio, but spent a year in 1921 to 1922 on a farm in Benson, Vermont, where Wheeler attended a one-room school. When they returned to Youngstown he attended Rayen High School.

After graduating from Baltimore City College high school in 1926, Wheeler entered Johns Hopkins University with a scholarship from the state of Maryland. He published his first scientific paper in 1930, as part of a summer job at the National Bureau of Standards. He earned his doctorate in 1933. His dissertation research work, carried out under the supervision of Karl Herzfeld, was on the "Theory of the Dispersion and Absorption of Helium". He received a National Research Council fellowship, which he used to study under Gregory Breit at New York University in 1933 and 1934, and then in Copenhagen under Niels Bohr in 1934 and 1935. In a 1934 paper, Breit and Wheeler introduced the Breit–Wheeler process, a mechanism by which photons can be potentially transformed into matter in the form of electron–positron pairs.

Early Career and Breakthrough of John Archibald Wheeler

The University of North Carolina at Chapel Hill made Wheeler an associate professor in 1937, but he wanted to be able to work more closely with experts in particle physics. He turned down an offer in 1938 of an associate professorship at Johns Hopkins University in favor of an assistant professorship at Princeton University. Although it was a lesser position, he felt that Princeton, which was building up its physics department, was a better career choice. He remained a member of its faculty until 1976.

In his 1937 paper "On the Mathematical Description of Light Nuclei by the Method of Resonating Group Structure", Wheeler introduced the S-matrix—short for scattering matrix—"a unitary matrix of coefficients connecting the asymptotic behavior of an arbitrary particular solution [of the integral equations] with that of solutions of a standard form". Wheeler did not pursue this idea, but in the 1940s Werner Heisenberg developed the idea of the S-matrix into an important tool in elementary particle physics.

In 1938 Wheeler joined Edward Teller in examining Bohr's liquid drop model of the atomic nucleus; they presented their results at a meeting of the American Physical Society in New York. Wheeler's Chapel Hill graduate student Katharine Way also presented a paper, which she followed up in a subsequent article, detailing how the liquid drop model was unstable under certain conditions. Due to a limitation of the liquid drop model, they all missed the opportunity to predict nuclear fission. In 1939, Bohr brought the news of Lise Meitner's and Otto Frisch's discovery of fission to America. Bohr told Leon Rosenfeld, who informed Wheeler.

Bohr and Wheeler set to work applying the liquid drop model to explain the mechanism of nuclear fission. As the experimental physicists studied fission, they uncovered puzzling results. George Placzek asked Bohr why uranium seemed to fission with both fast and slow neutrons. Walking to a meeting with Wheeler, Bohr had an insight that fission at low energies was due to the uranium-235 isotope, while at high energies it was mainly due to the far more abundant uranium-238 isotope. They co-wrote two more papers on fission. Their first paper appeared in Physical Review on September 1, 1939, the day Germany invaded Poland, starting World War II.

Considering the notion that positrons were electrons traveling backward in time, in 1940 Wheeler conceived his one-electron universe postulate: that there was in fact only one electron, bouncing back and forth in time. His graduate student Richard Feynman found this hard to believe, but the idea that positrons were electrons traveling backward in time intrigued him, and Feynman incorporated the notion of the reversibility of time in his Feynman diagrams.

Manhattan Project

Soon after the Japanese bombing of Pearl Harbor brought the U.S. Into World War II, Wheeler accepted a request from Arthur Compton to join the Manhattan Project's Metallurgical Laboratory at the University of Chicago. He moved there in January 1942, joining Eugene Wigner's group, which was studying nuclear reactor design. He co-wrote a paper with Robert F. Christy on "Chain Reaction of Pure Fissionable Materials in Solution", which was important in the plutonium purification process. It was declassified in December 1955. He gave the neutron moderator its name, replacing Enrico Fermi's term, "slower downer".

Source: adapted from Wikipedia (https://en.wikipedia.org/wiki/John_Archibald_Wheeler), text available under CC BY-SA 4.0.