John Archibald Wheeler

At 94 years old, John Archibald Wheeler physical status not available right now. We will update John Archibald Wheeler's height, weight, eye color, hair color, build, and measurements.

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 the 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 the faculty there until 1976.

In a 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". Werner Heisenberg subsequently developed the idea of the S-matrix in the 1940s. Due to the problematic divergences present in quantum field theory at that time, Heisenberg was motivated to isolate the essential features of the theory that would not be affected by future changes as the theory developed. In doing so he was led to introduce a unitary "characteristic" S-matrix, which became an important tool in particle physics.

Wheeler did not develop the S-matrix, but 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 in 1938. 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. The news of Lise Meitner and Otto Frisch's discovery of fission was brought to America by Bohr in 1939. 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 very fast and very slow neutrons. Walking to a meeting with Wheeler, Bohr had an insight that the 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 in Europe.

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

Later career in academia

After concluding his Matterhorn Project work, Wheeler resumed his academic career. In a 1955 paper, he theoretically investigated the geon, an electromagnetic or gravitational wave that is held together in a confined region by the attraction of its own field. He coined the name as a contraction of "gravitational electromagnetic entity". He found that the smallest geon was a toroid the size of the Sun, but millions of times heavier.

During the 1950s, Wheeler formulated geometrodynamics, a program of physical and ontological reduction of every physical phenomenon, such as gravitation and electromagnetism, to the geometrical properties of a curved space-time. His research on the subject was published in 1957 and 1961. Wheeler envisaged the fabric of the universe as a chaotic sub-atomic realm of quantum fluctuations, which he called "quantum foam".

General relativity had been considered a less respectable field of physics, being detached from experiment. Wheeler was a key figure in the revival of the subject, leading the school at Princeton University, while Dennis William Sciama and Yakov Borisovich Zel'dovich developed the subject at Cambridge University and the University of Moscow, respectively. Wheeler and his students made substantial contributions to the field during the Golden Age of General Relativity.

While working on mathematical extensions to Einstein's general relativity in 1957, Wheeler introduced the concept and word wormhole to describe hypothetical "tunnels" in space-time. Bohr asked if they were stable and further research by Wheeler determined that they are not. His work in general relativity included the theory of gravitational collapse. He used the term black hole in 1967 during a talk he gave at the NASA Goddard Institute of Space Studies (GISS), although the term had been used earlier in the decade. Wheeler said the term was suggested to him during a lecture when a member of the audience was tired of hearing Wheeler say "gravitationally completely collapsed object". Wheeler was also a pioneer in the field of quantum gravity due to his development, with Bryce DeWitt, of the Wheeler–DeWitt equation in 1967. Stephen Hawking later described Wheeler and DeWitt's work as the equation governing the "wave function of the Universe".

Wheeler left Princeton University in 1976 at the age of 65. He was appointed as the 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. Misner, Thorne and Wojciech Zurek, all former students of Wheeler, wrote that:

Wheeler's delayed choice experiment is actually several thought experiments in quantum physics that he proposed, with the most prominent among them appearing in 1978 and 1984. These experiments are attempts to decide whether light somehow "senses" the experimental apparatus in the double-slit experiment that it will travel through, and adjusts its behavior to fit by assuming the appropriate determinate state, or whether light remains in an indeterminate state, neither wave nor particle, and responds to the "questions" asked of it in either a wave-consistent manner or a particle-consistent manner, depending on the experimental arrangements that ask these "questions".

Wheeler's graduate students included Jacob Bekenstein, Hugh Everett, Richard Feynman, David Hill, Bei-Lok Hu, John R. Klauder, Charles Misner, Kip Thorne, William Unruh, Robert M. Wald, Katharine Way, and Arthur Wightman. Wheeler gave a high priority to teaching, and continued to teach freshman and sophomore physics, saying that the young minds were the most important. At Princeton he supervised 46 PhDs, more than any other professor in the Princeton physics department. With Kent Harrison, Kip Thorne and Masami Wakano, Wheeler wrote Gravitation Theory and Gravitational Collapse (1965). This led to the voluminous general relativity textbook Gravitation (1973), co-written with Misner and Thorne. Its timely appearance during the golden age of general relativity and its comprehensiveness made it an influential relativity textbook for a generation. Wheeler teamed up with Edwin F. Taylor to write Spacetime Physics (1966) and Scouting Black Holes (1996).

Alluding to Wheeler's "mass without mass", the festschrift honoring his 60th birthday was titled Magic Without Magic: John Archibald Wheeler: A Collection of Essays in Honor of his Sixtieth Birthday (1972). His writing style could also attract parodies, including one by "John Archibald Wyler" that was affectionately published by a relativity journal.

Wheeler speculated that reality is created by observers in the universe. "How does something arise from nothing?", he asked about the existence of space and time. He also coined the term "Participatory Anthropic Principle" (PAP), a version of a Strong Anthropic Principle.

In 1990, Wheeler suggested that information is fundamental to the physics of the universe. According to this "it from bit" doctrine, all things physical are information-theoretic in origin:

In developing the Participatory Anthropic Principle (PAP), an interpretation of quantum mechanics, Wheeler used a variant on Twenty Questions, called Negative Twenty Questions, to show how the questions we choose to ask about the universe may dictate the answers we get. In this variant, the respondent does not choose or decide upon any particular or definite object beforehand, but only on a pattern of "Yes" or "No" answers. This variant requires the respondent to provide a consistent set of answers to successive questions, so that each answer can be viewed as logically compatible with all the previous answers. In this way, successive questions narrow the options until the questioner settles upon a definite object. Wheeler's theory was that, in an analogous manner, consciousness may play some role in bringing the universe into existence.

From a transcript of a radio interview on "The Anthropic Universe":

In 1979, Wheeler spoke to the American Association for the Advancement of Science (AAAS), asking it to expel parapsychology, which had been admitted ten years earlier at the request of Margaret Mead. He called it a pseudoscience, saying he did not oppose earnest research into the questions, but he thought the "air of legitimacy" of being an AAAS-Affiliate should be reserved until convincing tests of at least a few so-called psi effects could be demonstrated. In the question and answer period following his presentation "Not consciousness, but the distinction between the probe and the probed, as central to the elemental quantum act of observation", Wheeler incorrectly stated that J. B. Rhine had committed fraud as a student, for which he apologized in a subsequent letter to the journal Science. His request was turned down and the Parapsychological Association remained a member of the AAAS.

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