Wheeler Refers to Collapsed Stars as “Black Holes” Summary

  • Last updated on November 10, 2022

In a paper relating to the collapse of massive stars, physicist John Archibald Wheeler referred to the resulting point mass as a “black hole,” because no light or radiation could escape its gravity. The term sparked both the scientific and the popular imagination, as black holes became both popular objects of study and popular subjects of speculative fiction.

Summary of Event

In the spring of 1968, John Archibald Wheeler published an article that appeared in both The American Scholar and The American Scientist in which he used the term “black hole” for the first time. He had become convinced that the mechanism used to hypothesize that stellar collapse could proceed only so far before encountering physical barriers was inadequate to prevent total collapse. He proposed that total collapse into a “singularity” (no size, infinite density) would not allow any light to escape, hence the term “black hole.” Black holes Astronomy;black holes [kw]Wheeler Refers to Collapsed Stars as “Black Holes” (Spring, 1968) [kw]Stars as “Black Holes,” Wheeler Refers to Collapsed (Spring, 1968)[Stars as Black Holes] [kw]"Black Holes," Wheeler Refers to Collapsed Stars as (Spring, 1968)[Black Holes] Black holes Astronomy;black holes [g]North America;Spring, 1968: Wheeler Refers to Collapsed Stars as “Black Holes”[09710] [g]United States;Spring, 1968: Wheeler Refers to Collapsed Stars as “Black Holes”[09710] [c]Astronomy;Spring, 1968: Wheeler Refers to Collapsed Stars as “Black Holes”[09710] [c]Science and technology;Spring, 1968: Wheeler Refers to Collapsed Stars as “Black Holes”[09710] Wheeler, John Archibald Schwarzschild, Karl Einstein, Albert Oppenheimer, J. Robert

Wheeler has enjoyed an exceptionally long and productive career in theoretical physics. His skills as a classroom teacher are legendary. He completed a Ph.D. at the age of twenty-two. After a year of study with Niels Bohr in Copenhagen, he taught at the University of North Carolina before moving to Princeton University in 1938. He collaborated with many of the most significant physicists of the twentieth century. In 1929, in association with Bohr, he published the definitive statement of the theory of fission and predicted the undiscovered plutonium 239 as a synthesizable isotope that would be useful in nuclear weapons.

Wheeler was the leader of a research group that developed the methods for controlling a nuclear reactor by preparing for “poisoning” by fission products that would absorb the bombarding neutrons. His work in nuclear particle physics resulted in the prediction of polyelectrons, composed of clusters of three or more electrons. In 1949 and 1950, he joined Edward Teller and others to develop the hydrogen bomb. He proposed, in 1953, the “collective” model of the atomic nucleus, a many-particled kinematic version of the functioning of the atomic nucleus. He then studied general relativity, which he called geometrodynamics, exploring the relation between field theory and particle physics.

Wheeler found gravitational collapse the most interesting link between particle physics and the theory of gravitation as expressed in general relativity. Since the publication of Karl Schwarzschild’s study completed during World War I, months after Albert Einstein published the theory of general relativity, it had been suspected that a sufficiently large mass of dense matter should be unable to avoid collapse. Little, however, was known of the behavior of matter at extremely high pressure. Wheeler investigated matter and radiation mixtures. By 1954, he was evaluating pure gravitational-electromagnetic entities called “geons,” which were stable against the loss of photons. Wheeler’s geons possessed energy and thus mass, yet there was no place one could say the mass exists in space-time. He thereby gave classical relativity theory a new comprehensiveness and laid the foundation for the study of gravitational waves.

In 1955, Wheeler proposed “wormholes” with electric lines of force that produced a different explanation of electrical charge. He pressed the position that space is not described by any single geometry but by different geometries under differing conditions which resonate with one another. By 1957, he published a paper with a technique for matching two different space-time geometries. That same year, he published the pioneering analysis of the pulsation and stability of black holes. This work culminated in the publication of geometrodynamics in 1962.

Super-space built Wheeler’s reputation as an authority in gravitational studies and contributed to his successful proposal of black holes as the appropriate name for collapsed objects. He indicated that space only looks flat from a distance. At close range, however, it is a chaotic froth. He speculated that the physical constants could be reset with different values at each successive collapse and big bang, for he believed that there was sufficient mass in the universe to generate an eventual collapse. He further suggested that life might be unique to this particular cycle.

John Archibald Wheeler.

(Library of Congress)

In late 1915, Schwarzschild had investigated the geometry of space-time near massive objects. For a star of any given mass, there is a radius such that if the star becomes smaller, it separates itself from surrounding space-time. Objects could enter inside this radius, but nothing could exit. Schwarzschild’s radius or “event horizon” became part of theoretical astrophysics, but whether real stars collapsed was unknown.

In 1939, J. Robert Oppenheimer, George Michael Volkoff Volkoff, George Michael , and Hartland Snyder Snyder, Hartland published a paper in the Physical Review demonstrating that a mass about three times that of the sun would continue to collapse beyond a white dwarf or a neutron star to a singularity. All that would persist was its gravitation, yet physicists doubted that such a bizarre result could be reality, so they searched for a mechanism that would prevent collapse. By 1967, pulsars, those mysterious rapidly rotating and emitting objects, had been discovered. The proposed solution was collapsed rotating objects, called neutron stars by Thomas Gold in 1968.

The possible collapse into an object so dense that no radiation escapes was aptly named a black hole. Previously, the black hole was variously identified as a Schwarzschild singularity, a collapsed star, or a frozen star. These names focused upon optical appearances outside the event horizon. For Wheeler, the event horizon became the surface of the black hole and the external geometry the gravitational field of the black hole. Wheeler never indicated that he was giving it a new name. He simply wrote as if that is what it had always been called, and others followed suit. (In the 1970’s, black holes captured public attention, assisted by a general fascination with disaster. The black hole represented the ultimate disaster.)

Wheeler continued his studies of black holes and was among the pioneers who established that black holes were very simple objects, having only mass, electric charge, and a rate of spin. Theoretical work centered on two issues: Were there physical conditions in the universe that would lead to black holes, and would they be stable? Others firmly established that there were many large enough stars and that no effective explanation to avoid collapse had been found. Stability was a more difficult issue, for many physicists believed that a black hole would fall apart if there were perturbations in its surface or motions. Others argued that a black hole would not form if the star was not spherical. Wheeler and his associates calculated away these and other difficulties. Black holes began to appear as inevitable, potential sources of great energy in the centers of galaxies. The search was launched to find them, with Wheeler suggesting many ways they could be identified by their gravitational effects and the release of energy as they captured mass before the event horizon was reached.

Significance

John Archibald Wheeler is a major figure in twentieth century particle and gravitational physics. Along with Schwarzschild, Oppenheimer, Roy Kerr, and Stephen W. Hawking, he stands as a pioneer in the understanding and theory of black holes. Among the most significant contributions Wheeler made was breaking down the psychological barrier that exists for scientists and public alike to believe in something that has an esoteric name. By giving the singularity a common name like black hole, Wheeler put it within reach and made acceptance of the unusual theoretical results easier.

Wheeler’s timing was also impeccable. While Wheeler and many others, especially Hawking, had been studying singularities for several years immediately after the radio discovery of the pulsars and their explanation in terms of neutron stars, the total collapse into singularities was the next logical step. By giving these objects a catchy name, Wheeler was able to bring them to attention and start the massive outpouring of interest that followed.

Black holes provide clues to the resolution of outstanding difficulties in cosmology. They have been proposed as explanations of the missing mass needed to bring the mass of the universe to a level where the expansion will be slow and eventually reverse into the next phase of collapse. They have been proposed as a source of the massive energy outpouring of the quasars. Further, they appear to hold significant implications for studies in the field of general relativity. Wheeler has pioneered in seeking a theory that would combine quantum physics and general relativity into a theory of quantum gravity, a first step in formulating the long-sought unified field theory in relativity studies. At the present time, relativistic equations break down when confronted with the infinite forces and gravity of a singularity.

The most fruitful consequence of the naming and study of black holes has been the significant research stimulated by the effort to find black holes. While incontrovertible proof is not yet available, Cygnus X-1 Cygnus X-1[Cygnus X 1] and two or three other dynamical doubles where objects on the order of 10 solar masses are invisible are circumstantial candidates for status as black holes. The search to strengthen the evidence continues, and exciting results will continue to develop. Black holes Astronomy;black holes

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Barrow, John D., Paul C. W. Davies, and Charles L. Harper, Jr., eds. Science and Ultimate Reality: Quantum Theory, Cosmology, and Complexity. New York: Cambridge University Press, 2004. Compilation of essays assembled in honor of Wheeler’s ninetieth birthday. Devotes considerable space to discussion of the significance of Wheeler’s work and his contributions to cosmology and quantum physics. Bibliographic references and index.
  • citation-type="booksimple"

    xlink:type="simple">Bartusiak, Marcia. Thursday’s Universe. New York: Times Books, 1986. Chapter 3 contains an excellent summary of the theory of black holes in understandable language. Wheeler’s theoretical work is placed in historical and theoretical context.
  • citation-type="booksimple"

    xlink:type="simple">Harrison, Edward R. Cosmology: The Science of the Universe. Cambridge, England: Cambridge University Press, 1981. A remarkably comprehensive perspective that includes both history and theory of cosmology. The work of Wheeler, while not prominent, is placed wonderfully and colorfully in context. Harrison, another Wheeler collaborator, reflects much of Wheeler’s style in his own.
  • citation-type="booksimple"

    xlink:type="simple">Klauder, John R., ed. Magic Without Magic: John Archibald Wheeler. San Francisco: W. H. Freeman, 1971. A collection of essays honoring Wheeler’s sixtieth birthday in 1971. The introduction is a fascinating biographical sketch well worth the reading. The essay on pages 475 to 485 treats with almost reverential awe another aspect of Wheeler’s career and collaboration.
  • citation-type="booksimple"

    xlink:type="simple">Misner, Charles W., Kip S. Thorne, and John A. Wheeler. Gravitation. San Francisco: W. H. Freeman, 1971. Although technical, it should be scanned to get a feel for how mathematical this subject is, how much can be said, and how complicated the theory is. Pages 619 to 939 contain scattered historical notes including a delightful dialogue on pages 872 to 875 indicating why the black hole is aptly named.
  • citation-type="booksimple"

    xlink:type="simple">Raine, Derek, and Edwin Thomas. Black Holes: An Introduction. London: Imperial College Press, 2005. Designed for readers who are seeking a more advanced treatment than popular works provide but who lack the necessary mathematics and physics to understand technical discussions of the subject. Bibliographic references and index.
  • citation-type="booksimple"

    xlink:type="simple">Thorne, Kip S., and Wojciech H. Zurek. “John Archibald Wheeler: A Few Highlights of His Contributions to Physics.” Foundations of Physics 16 (February, 1986): 79-86. Consists of a collection of significant quotations from Wheeler’s published works demonstrating points at which he made contributions. There are illuminating comments by the authors on the meaning of the quotations.
  • citation-type="booksimple"

    xlink:type="simple">Wheeler, John Archibald. “Our Universe: The Known and the Unknown.” American Scholar 37 (Spring, 1968): 248-274. The famous paper in which he named the black hole. An excellent summary of the state of cosmology in 1968 that touched upon a number of controversial issues in a balanced fashion.

Reber Publishes the First Radio Maps of the Galaxy

Ryle’s Radio Telescope Locates the First Known Radio Galaxy

Gamow Develops the Big Bang Theory

Mössbauer Effect Is Used to Detect Gravitational Redshifting

Discovery of the First X-Ray Source Outside the Solar System

Schmidt Identifies Quasars

Bell Discovers Pulsars

Categories: History Content