Bulletin of the American Physical Society
2009 APS April Meeting
Volume 54, Number 4
Saturday–Tuesday, May 2–5, 2009; Denver, Colorado
Session B5: The Scientific Legacy of John Wheeler |
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Sponsoring Units: GGR FHP Chair: James Hartle, University of California, Santa Barbara Room: Governor's Square 15 |
Saturday, May 2, 2009 10:45AM - 11:21AM |
B5.00001: John Wheeler, 1933 - 1959: Particles and Weapons Invited Speaker: Kenneth Ford During the early part of his career, John Archibald Wheeler made an astonishing number of contributions to nuclear and particle physics, as well as to classical electrodynamics, often in collaboration with another physicist. He was also a major contributor to the Manhattan Project (in Chicago and Hanford rather than Los Alamos), and, following World War II, became an influential scientific cold warrior. His early achievements in physics include the calculated scattering of light by light (with Gregory Breit), the prediction of nuclear rotational states (with Edward Teller), the theory of fission (with Niels Bohr), action-at-a-distance electrodynamics (with Richard Feynman), the theory of positronium, the universal weak interaction (with Jayme Tiomno), and the proposed use of the muon as a nuclear probe particle. He gained modest fame as the person who identified xenon 135 as a reactor poison. His Project Matterhorn contributed significantly to the design of the H bomb, and his Project 137, which he had hoped would flower into a major defense lab, served as the precursor to the Jason group. [Preview Abstract] |
Saturday, May 2, 2009 11:21AM - 11:57AM |
B5.00002: John Wheeler, 1952 - 1976: Black Holes and Geometrodynamics Invited Speaker: Kip S. Thorne In 1952 John Wheeler turned his attention from nuclear physics and national defense to a backwater of physics: general relativity. Over the next 25 years, with students and postdocs he led a ``revolution'' that made relativity a major subfield of fundamental physics and a tool for astrophysics. Wheeler viewed curved spacetime as a nonlinear dynamical entity, to be studied via tools of geometrodynamics (by analogy with electrodynamics) -- including numerical relativity, for which his students laid the earliest foundations. With Joseph Weber (his postdoc), he did theoretical work on gravitational waves that helped launch Weber on a career of laying foundations for modern gravitational-wave detectors. Wheeler and his students showed compellingly that massive stars must form black holes; and he gave black holes their name, formulated the theory of their pulsations and stability (with Tullio Regge), and mentored several generations of students in seminal black-hole research (including Jacob Bekenstein's black-hole entropy). Before the discovery of pulsars, Wheeler identified magnetized, spinning neutron stars as the likely power sources for supernova remnants including the Crab nebula. He identified the Planck length and time as the characteristic scales for the laws of quantum gravity, and formulated the concept of quantum fluctuations of spacetime geometry and quantum foam. With Bryce DeWitt, he defined a quantum wave function on the space of 3-geometries and derived the Wheeler-DeWitt equation that governs it, and its a sum-over-histories action principle. Wheeler was a great inspiration to his colleagues and students, pointing the directions toward fruitful research problems and making intuitive-leap speculations about what lies beyond the frontiers of knowledge. Many of his ideas that sounded crazy at the time were ``just crazy enough to be right''. [Preview Abstract] |
Saturday, May 2, 2009 11:57AM - 12:33PM |
B5.00003: John Wheeler, 1976 - 1996: Law Without Law and Quantum Information Invited Speaker: Wojciech H. Zurek John Archibald Wheeler moved to Austin, Texas in the summer of 1976. With the change of University came a shift in emphasis, from general relativity in Princeton to the foundations of quantum theory in Texas. As before, Wheeler was a ``radical conservative'', asking far out questions, and pushing the known laws of physics to their breaking point on the way to an answer or -- better yet -- to a deeper conundrum. As always, his ideas were original, bold, and profound. As usual, Wheeler exerted his greatest influence through students and junior colleagues he inspired. The delayed -- choice experiment he suggested is one example of ``radical conservatism''. It dramatically illustrates the role of the observer in defining a ``phenomenon'' -- in determining what happens (or even what has already happened!) in quantum theory. Wheeler's interest in the foundations of quantum theory and its relation to information (emphasis that echoed Bohr's views of quantum states) pre-saged development of what is now known as the physics of information. [Preview Abstract] |
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