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John Archibald Wheeler

March 25, 2019

The US space program didn't just give us men on the Moon, it also gave us such technological marvels as space food sticks and integrated circuits. Likewise, the Manhattan Project gave us some things much better than the atomic bomb. It also gave us nuclear power and a means to power distant spacecraft such as Cassini that gave us stunning images of Saturn and its moons.

One other legacy of the Manhattan Project was its physics alumni. This included numerous Nobel Laureates such as Richard Feynman, Hans Bethe, and Glenn Seaborg. It also included theorist, John Archibald Wheeler (1911-2008), who had a huge impact on physics, starting even before World War II. Wheeler wasn't awarded the Nobel Prize, but he won nearly every other prize in physics. He also left a legacy of nearly 50 Ph.D. students. His coauthor and colleague, Kip Thorne (b. 1940), has posted a reminiscence of Wheeler on arXiv.[1]

Physicist, John Archibald Wheeler (1911-2008), as he appeared in 1985

Physicist, John Archibald Wheeler (1911-2008), as he appeared at the 1985 Hermann Weyl Conference, Kiel, Germany.

Wheeler's education included one year at a one-room school in Benson, Vermont, from 1921-1922. He must have enjoyed New England, since he bought half of High Island, Maine, for a vacation home in 1957.[1]

(Wikimedia Commons image by Emielke.)


Wheeler was a precocious young physicist who entered Johns Hopkins University in 1927 at the age of sixteen. He bypassed a bachelor's degree and proceeded to obtain a Ph.D. under Karl Herzfeld in 1933 for a dissertation on the scattering and absorption of light by helium atoms in 1933.[1] His interests took him into several diverse areas of theoretical physics. Wheeler said that his scientific life had three phases:[2]
1 - Everything is particles.
2 - Everything is fields.
3 - Everything is information.

Everything is particles

Wheeler's particle research began during a postdoctoral year (1933-34) with Gregory Breit at New York University.[1] Wheeler and Breit calculated the scattering of photons from each other and discovered Breit-Wheeler pair production. This process, the complement of mass–energy equivalence in which mass is converted to energy, has two gamma ray photons combine to produce mass in the form of an electron and a positron. It's only after the development of high intensity lasers that the process was experimentally confirmed.[3]

Breit-Wheeler pair production

Breit-Wheeler pair production, in which the interaction of two gamma ray photons produces an electron and a positron. This is the complement of what's seen in nature, where the annihilation of an electron and a positron produces gamma rays.

Breit and Wheeler didn't believe that their process would never be seen in a laboratory, but that was before we had such technology as high energy lasers and accelerators.

(Wikimedia Commons image by Mathieu Michel Lobet.)


After World War II, the best prospect for observation of high energy interactions between elementary particles was through cosmic ray studies. In response, Wheeler created and led a cosmic-ray laboratory at Princeton University, where he took a special interest in the muon. Demonstrating that the muon had the same properties as an electron with a higher mass, Wheeler also looked at atomic analogs in which electrons were replaced by muons. The muons in such atoms interact more strongly with the nucleus than electrons.

Building on the Heisenberg uncertainty principle, Wheeler conjectured that the geometry of spacetime fluctuates at very short time intervals in regions defined by the Planck length.[1,3] These fluctuations distort the supposedly smooth spacetime to create what's called a quantum foam. The foam includes wormholes, described classically by Hermann Weyl in 1924, but explored in detail by Wheeler and his students in the 1950s and early 1960s.[1]

One of Wheeler's most interesting conjectures was that of the one-electron universe. This explains why all electrons have the same properties, since they are the same electron moving backwards and forwards in time. This 1942 idea of wheeler, that also saw positrons as electrons moving backwards in time, was cited by Feynman as an important idea in his formulation of quantum electrodynamics, an achievement for which he won the Nobel Prize.[1]

Everything is Fields

Relativity had been overshadowed by particle studies in the 1940s, but Wheeler resurrected the topic by teaching a full year course on relativity at Princeton in 1952.[1] This was the first relativity course there since 1941.[1] His interest in relativity was sparked by his reading the 1938-39 work of Robert Oppenheimer and George Volkoff on neutron stars, and Oppenheimer's work with Hartland Snyder on the gravitational collapse of massive stars into what Wheeler named black holes seventeen years later.[1,4-5]

As Oppenheimer and Snyder observed, stellar collapse would cause the star "... to close itself off from any communication with a distant observer; only its gravitational field persists."[4-5] Most physicists were skeptical that such an infinite collapse was possible. Russian physicist and eventual Nobel Laureate, Lev Landau, thought that this would be disallowed by something in quantum mechanics.[5]

Wheeler encouraged electrical engineer, Joseph Weber (1919-2000), a faculty member at the University of Maryland, in his quest to detect gravitational waves,[1] Weber's experiment monitored the change in the size of an object, a change that was estimated to be less than the diameter of a proton for his detector, by resonant detection. I described Weber's aluminum cylinder detector, called a Weber bar in an earlier article (Gravitational Waves, February 3, 2014). Weber did not succeed, and it was only by means of a much more elaborate detector at the Laser Interferometer Gravitational-Wave Observatory (LIGO) that gravitational wave were first detected on September 14, 2015.

Wheeler became interested in what he called geometrodynamics, the geometry of spacetime. He invented a bootstrapped object he called a geon. A geon is an electromagnetic (or gravitational) wave which holds itself together in a toroidal or spherical region of space because of the gravitational attraction of its own field energy. Wheeler thought that geons could be a model for elementary particles, but classical geons are unstable since they leak radiation.[1] Classical electrons are likewise unstable, since they radiate energy in their orbits around the nucleus, finally spiraling into it.

Portion of Geons dust jacket

A physicist's purposeful pose.

The culmination of Wheeler's adventures in relativity is the 1973 publication of the book, Gravitation with coauthors Charles Misner and Kip Thorne.[6]

Wheeler also published an autobiography entitled, "Geons, Black Holes, and Quantum Foam: A Life in Physics," in 1998.

(Portion of Geons dust jacket, scan of my copy. Click for larger image.)


Everything is Information

As I discussed in my article, Metaphysics (November 12, 2018), metaphysics is the branch of philosophy that looks at issues beyond physics, such as prime causes and purposes. Philosophical cosmology, as distinct from physical cosmology, is the study of the conceptual foundation of the universe, which includes the ultimate existential question of why anything should exist. Wheeler became interested in these ideas in his later career.

It's been said that if the only tool you have is a hammer, everything is a nail. Today's hammer is the computer and its academic discipline, computer science. Wheeler's experience with the strange couplings in spacetime led him to the idea that the universe might be a self-excited circuit, a bootstrapped system responsible for its own existence, and that information theory is the basis of existence[1]. He summarized this idea in the phrase, "it from bit." I wrote about this idea in an earlier article (It from Bit, July 8, 2013).

The "it from bit" idea that physics at a fundamental level is based on answers to "yes-no" questions was qualitatively expressed in 1977 by Columbia University physicist, Frederick W. Kantor, but Wheeler gave it a mathematical framework in a 1989 paper.[8] Wheeler had a strong interpretation of "it from bit," imagining these bits to be "quanta of reality,"
"I suggest that we may never understand this strange thing, the quantum, until we understand how information may underlie reality. Information may not be just what we 'learn' about the world. It may be what 'makes' the world.[7] (My emphasis)
"It from bit" would explain why the laws of physics are so easily expressed using mathematical equations. This is the idea that Eugene Wigner expressed in his May 11, 1959, Richard Courant lecture in mathematical sciences at New York University, "The Unreasonable Effectiveness of Mathematics in the Natural Sciences."[9]

John A. Wheeler Autograph

John A. Wheeler Autograph. Wheeler autographed his 1998 autobiography, "Geons, Black Holes, & Quantum Foam," for me at a symposium on the history of quantum mechanics in New York City in 2000.


References:

  1. Kip S. Thorne, "John Archibald Wheeler: A Biographical Memoir," arXiv, January 20, 2019.
  2. Richard Webb, "John Wheeler - Three ages of man," Nature Physics, vol. 4 (May 1, 2008), p. 355, https://doi.org/10.1038/nphys951.
  3. Gail Wilson, "Scientists discover how to turn light into matter after 80-year quest," Imperial College Press Release, May 19, 2014.
  4. J. R. Oppenheimer and H. Snyder, "On continued gravitational contraction," Physical Review, vol. 56, no. 5 (September 1, 1939), pp. 455-459, DOI:https://doi.org/10.1103/PhysRev.56.455.
  5. David Lindley, "Focus: Landmarks—Forgotten Black Hole Birth," Physics, vol. 13, no. 23, May 28, 2004.
  6. John Archibald Wheeler, Kip S. Thorne, and Charles W. Misner, Gravitation (2017 Revised Edition), Princeton University Press, 1279 pp. + xxvi, ISBN 0-7167-0344-0 (via Amazon).
  7. John Archibald Wheeler, Geons, Black Holes, and Quantum Foam: A Life in Physics, W. W. Norton & Company, Revised Paperback edition (February 17, 2000), ISBN: 978-0393319910, 416 pp. (via Amazon).
  8. J. A. Wheeler, "Information, physics, quantum: the search for links," Proceedings III International Symposium on Foundations of Quantum Mechanics, Tokyo, 1989, p. 354-368.
  9. Eugene P. Wigner, "The unreasonable effectiveness of mathematics in the natural sciences," Communications on Pure and Applied Mathematics, vol. 13, no. 1 (February 1960), doi:10.1002/cpa.3160130102, pp. 1-14. PDF file available, here.
  10. Steven Weinberg, Austin M. Gleeson, and J. Craig Wheeler, "Documents of the General Faculty Report of the Memorial Resolution Committee for John A. Wheeler," University of Texas Website.
  11. Charles Misner, Kip Thorne, and Wojciech Zurek, "John Wheeler, relativity, and quantum information," Physics Today, vol. 62, no. 4 (April 1, 2009), pp. 40-46, https://doi.org/10.1063/1.3120895. Available as a PDF file here.

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