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Bondi, Hermann

BONDI, HERMANN

(b. Vienna, Austria, 1 November 1919; d. Cambridge, United Kingdom, 10 September 2005)

relativity theory, cosmology, astrophysics, science policy.

Bondi, an atheist Jewish Anglo-Austrian, was an eminent mathematical physicist, astronomer, and cosmolo-gist. He is probably best known as one of the chief architects of the steady state model of the universe, which he defended between 1948 and the mid-1960s when it was disproved by observations. However, it would be unfair to identify his scientific work with the steady state theory. From 1947 to the 1990s, Bondi contributed to a variety of problems in astrophysics and relativity theory, and he was a central figure in the renaissance of general relativity, roughly the 1955–1975 period.

Bondi’s interest in and contributions to science were far from limited to theoretical physics and astronomy. More than able as an organizer and administrator, from the late 1960s, Bondi got increasingly involved in science policy, internationally as well as on the government level. He was instrumental in the establishment of the European Space Research Organization, served as chief scientific advisor to the British government, and from 1983 to 1990, he was master of Churchill College, University of Cambridge. He served as secretary of the Royal Astronomical Society 1956–1964. Bondi received many honors for his contributions to science and science policy. He became a Fellow of the Royal Society in 1959, and was awarded the Einstein Society Gold Medal in 1983, the Gold Medal of the Institute of Mathematics and its Applications in 1988, the Planetary Award in 1993, and the Gold Medal of the Royal Astronomical Society in 2001. He was knighted (Knight Commander of the Order of Bath) in 1973.

In 1947, Bondi married Christine Stockman, an astrophysics research student supervised by Fred Hoyle. Together with her husband, Christine Bondi published several papers on stellar structure. The couple had five children, two sons and three daughters. His wife and children survived him.

Education and Early Career. Bondi belonged to a nonreligious Jewish family that had moved from Germany to Vienna in 1884. He attended a Realgymnasium (secondary school focused on science, rather than traditional classical education), where he demonstrated a remarkable talent for mathematics and physics. When Arthur Eddington happened to be in Vienna in 1936, the sixteen-year-old schoolboy managed to meet him, which fueled his ambitions of following a career in science. With the help of Abraham Frankel, his great-uncle and an eminent mathematician at the Hebrew University in Jerusalem, Bondi succeeded in being admitted as a foreign student at Trinity College, Cambridge, where he arrived in the fall of 1937, not yet eighteen years old. This was half a year before Austria became part of the Third Reich and adopted Hitler’s racial laws against the Jewish population. However, young Bondi’s decision to leave Austria were not politically motivated, but due to his wish to study in Cambridge.

Bondi had not been long in Cambridge as an undergraduate student of mathematics when Germany invaded Poland; Britain and France declared war on Germany a couple of days later. In a letter of recommendation, Eddington described Bondi as “a mathematical student of great brilliance and promise,” but it did not prevent him from being interned in May 1940. He was, after all, a citizen of a nation with which England was at war. Bondi spent most of the time until August 1941 in an internment camp in Quebec, Canada, where he happened to meet another Austrian internee, Thomas Gold, who studied engineering at Cambridge University. Bondi and Gold became close friends and used much of their time in the camp to discuss questions of physics. After returning to England, Bondi took up his studies in theoretical physics under the supervision of the distinguished mathematician and geophysicist Harold Jeffreys. He made his debut in the world of pure research in 1942 with a publication in the Proceedings of the Royal Society on the wind generation of waves on shallow water. But there was a war going on, and Bondi was subsequently drawn into military research, working for the admiralty on the theory of the magnetron, the kind of vacuum tube which was a central component in the radar sender.

Together with Gold, who in the summer of 1942 had been hired by Fred Hoyle’s radar group, Bondi rented a three-bedroom house in Dunsfold, near Witley. Hoyle frequently stayed in the house, with the result that the three young physicists established a lasting friendship based on their common conceptions of the situation in physics and astronomy. Unlike Bondi and Gold, Hoyle was already deeply interested in astrophysics and astronomy, subjects which were part of their long discussions. When Bondi returned to Cambridge in the summer of 1945, he was appointed assistant lecturer by the faculty of mathematics. Three years later he advanced to the permanent position as university lecturer. In 1946, he (as well as Gold) became a British subject. The following year, after he was married, he and his wife moved to a flat near Trinity College. The young couple continued to be in close contact with Hoyle and Gold.

By about 1945, Bondi had become interested in the general theory of relativity, a subject which was far from fashionable at the time but appealed to a few mathematically inclined physicists such as Bondi. He was asked by the Royal Astronomical Society to prepare a review report on cosmology and accepted the offer in spite of having only a superficial knowledge of the field. After having acquired the necessary background knowledge, he produced a masterly report on the state of cosmology, which was published in the Royal Astronomical Society’s Monthly Notices in early 1948. Although Bondi did not, at this stage, advocate a particular cosmological theory, his review paper reflected the same methodological commitments which shortly later were made explicit in the steady state theory. For example, he was quite critical towards the “extrapolatory” approach of relativistic cosmology, which he contrasted with the “deductive” approach of Edward A. Milne’s kinematic cosmology. In the first approach, the physicist extrapolates laboratory physics to form a comprehensive theory, which is then assumed to be valid for the entire universe; the alternative, which Bondi preferred, is to start from a small number of cosmological postulates and from these to deduce the corresponding physical theories. Bondi emphasized that, whatever the approach, any cosmological theory had to account for the repeatability of experiments, a claim that would be highlighted in the versio of steady state theory that he and Gold published a few months later.

The Steady State Theory of the Universe. To the extent that there existed a standard cosmology in the late 1940s, it was the evolutionary universe based on Einstein’s field equations of 1917, either in the big bang version or the ever-expanding but no-bang Lemaître-Eddington version. In their discussions of 1946 and 1947, Hoyle, Gold, and Bondi agreed that an evolutionary universe governed by general relativity was unsatisfactory in whatever version. They concluded that an unchanging yet expanding universe was preferable, and for this reason they postulated continual creation of matter to occur throughout space at such a rate that it compensated for the expansion and left the average density of matter constant (the idea came from Gold). In early 1948, Gold and Bondi and, independently, Hoyle worked out their two formulations of the steady state universe.

The theory presented in the 1948 Bondi-Gold paper was deductively founded on what they called the perfect cosmological principle, the postulate that the universe is uniform not only spatially but temporally as well: it has always looked the same. This principle, they claimed, was a fundamental axiom from which physical results should be deduced; if theoretical extrapolations from experiments conflicted with the principle, such as did the law of energy conservation, they had to be rejected. Bondi and Gold consequently denied that the universe could be described by the energy-conserving theory of general relativity. Moreover, they objected that relativistic cosmology was “utterly unsatisfactory” because it covered so many models and was based on so many free parameters that as a whole it could not be falsified observationally. In spite of the qualitative and philosophical flavor of their paper, Bondi and Gold could prove that their theory led to a number of definite predictions, including a specific rate of matter creation of about 10-43 g/s/cm3. It also followed from their theory that the metric of the steady state universe had to be of the De Sitter type, a flat space expanding exponentially. Whereas the Hubble parameter was a measure of the age of the universe in the relativistic theories, according to Bondi and Gold it was a true constant.

The Bondi-Gold theory differed methodologically from Hoyle’s version of steady state cosmology, but the two versions led to the same physics and were generally known as one theory. It was met with stiff resistance by critics who argued that it was contradicted by observations and also that it was methodologically flawed because it relied on the perfect cosmological principle. During the heated debate in the 1950s, Bondi defended the theory skillfully and largely successfully. For example, observations from 1948 indicated an excess reddening in the spectra of distant galaxies which seemed to contradict the steady state theory. Big bang cosmologists used this so-called Stebbins-Whitford effect to discredit the steady state theory, but in a critical review of the data Bondi, Gold, and Dennis Sciama showed in 1954 that the effect was spurious. Together with Raymond Lyttleton, Bondi suggested in 1959 a new “electrical cosmology” in conformity with the steady state theory and based on the hypothesis that the numerical charge of an electron differed slightly from the proton’s charge. The ingenious theory was short lived, for it quickly turned out that the predicted charge excess disagreed with experiments.

When it came to defending steady state cosmology from a methodological and philosophical point of view, Bondi was the theory’s leading spokesman. Inspired by Karl Popper’s falsificationist philosophy of science, he argued that the steady state theory was methodologically superior to the relativistic evolution theories because of its unique predictions. However, when the steady state theory ran into serious trouble in the early 1960s, first when confronted with radio astronomical data, Bondi did not act as a Popperian falsificationist. Rather than admitting that the steady state theory had been proved wrong, he questioned the reliability of the observations and preferred to suspend his judgment on the matter. Earlier criticisms of the steady state theory by some radio astronomers had proven to be based on bad data, and so it is perhaps not surprising that Bondi did not quickly reject the steady state theory when other attacks followed later. Neither did he follow Hoyle in inventing new versions of the steady state theory, and by 1965 (when the cosmic microwave background was discovered), he had quietly left cosmology as a research field.

Works in Relativity and Astrophysics. Bondi’s work in astrophysics started in the mid-1940s when he, inspired by Hoyle, got interested in how a star in a gas cloud accretes interstellar matter by way of gravitational attraction. His work in this area, in part done in collaboration with Hoyle and Lyttleton, continued for several years and led to concepts named after him, such as Bondi accretion and Bondi mass. In 1952, he collaborated with Edwin Salpeter in a study of thermonuclear reactions in stars, his only work in nuclear astrophysics.

Although Bondi denied that the universe was fully governed by general relativity, he had great confidence in Einstein’s gravitation theory and did much to revitalize it during the 1950s and 1960s. He made his entry in general relativity in 1947, when he examined the solution of the Einstein equations in the case of a spherically symmetric, inhomogeneous universe. This work was an extension of a theory put forward by Richard Tolman in 1934 which again relied on an investigation by Georges Lemaître from the previous year. The solution is generally known as the Tolman-Bondi model, although from a historical point of view Lemaître-Tolman model would be more appropriate. Bondi’s paper anticipated future developments in the field of inhomogeneous models and was considered of such importance that it was reprinted in 1999. In a paper of 1957, he analyzed the concept of negative mass in general relativity by constructing a solution to the Einstein equations in terms of hypothetical matter with repulsive gravitation.

Gravitational radiation was a subject that occupied Bondi for about thirty years. His papers in this area “are still canonical reading,” the relativist Andrzej Krasinski wrote in 1999 (p. 1778). In a series of papers between 1959 and 1988, some of them coauthored by Felix Pirani, Bondi conclusively showed that general relativity theory predicts gravitational waves and that these are not a coordinate effect but should be observable. He was particularly interested in plane waves, which he studied in great detail. He found that such waves could produce a relative acceleration in free test particles, from which he inferred that the waves transport energy. In one of his last scientific papers, published in 1988 with Pirani, he studied a mechanism for the conversion of gravitational energy into electromagnetic energy. In a couple of works (1967–1969), Bondi examined the radial motion of uniform spheres in general relativity, concluding that in certain cases the system would “bounce,” i.e., reverse its radial motion.

Among the books that Bondi wrote during his long scientific career, Cosmology (1952) was an excellent introduction to and survey of the contemporary state of cosmology, including relativistic cosmology as well as steady state theory and Edward A. Milne’s kinematic relativity. Reprinted in 1960, it was for a long time the standard textbook on the subject. In the early 1960s, he wrote two popular books, The Universe at Large (1961) and Relativity and Common Sense (1964), and in 1968, he published Assumption and Myth in Physical Science. His autobiography, focusing more on his administrative and political work than on his scientific contributions, appeared in 1990 under the title Science, Churchill & Me.

Statesman of Science. In spite of his scientific work being highly theoretical, Bondi was far from an ivory-tower scientist. As early as 1953, while deeply engaged in the cosmological controversy, he wrote a report on the floods that devastated parts of eastern England that year. It was largely as a result of Bondi’s report that the London Barrier was built a few years later. After he left King’s College, London, he began a parallel career in public service, first from 1967 to 1971 as director general for the European Space Research Organization, ESRO, the predecessor of ESA, the European Space Agency. From 1971 to 1984, Bondi worked as a high-level public servant, first as chief scientific advisor for the Ministry of Defense and subsequently as chief scientist in the Department of Energy, where he laid the groundwork for Britain’s first long-term energy policy. During the 1980–1984 period he served as chairman and chief executive of the Natural Environment Research Council. Remarkably, during these busy years in public service, he continued doing work in pure physics.

Bondi’s views on science and society were in line with the ideals of the Enlightenment era. He strongly believed in the social value of science and the social responsibility of scientists, including educational reforms based on science. He was active in the scientific education of the public and published several articles in the journal Physics Education. Philosophically, he was a follower of Popper, whom he greatly admired and in 1992 characterized as “the philosopher for science.” (When Popper died in 1994, Bondi wrote his obituary in Nature.) Since his childhood in Vienna Bondi had been an atheist, developing from an early age a view on religion that associated it with repression and intolerance. This view, which he shared with Hoyle, never left him. On several occasions he spoke out on behalf of freethinking, so-called, and became early on active in British atheist or “humanist” circles. From 1982 to 1999, he was president of the British Humanist Association, and he also served as president of the Rationalist Press Association of United Kingdom.

BIBLIOGRAPHY

Janus Project. “The Papers of Sir Hermann Bondi.” Bondi’s papers, contained in 109 archive boxes, are deposited at Churchill Archives Centre, Cambridge, England. Finding aid: http://janus.lib.cam.ac.uk.

WORKS BY BONDI

“On the generation of waves on shallow water by wind.” Proceedings of the Royal Society 181 (1942): 67–71.

“Spherical Symmetrical Models in General Relativity.” MonthlyNotices of the Royal Astronomical Society 107 (1947): 410–425.

“Review of Cosmology.” Monthly Notices of the RoyalAstronomical Society 108 (1948): 104–120.

With Thomas Gold. “The Steady-State Theory of the Expanding Universe.” Monthly Notices of the Royal Astronomical Society108 (1948): 252–270.

“On Spherically Symmetrical Accretion.” Monthly Notices of theRoyal Astronomical Society 112 (1952): 195–204.

Cosmology. Cambridge, U.K.: Cambridge University Press, 1952.

“Fact and Inference in Theory and Observation.” Vistas inAstronomy1 (1955): 155–162.

“Negative Mass in General Relativity.” Reviews of Modern Physics 29 (1957): 423–428.

“Some Philosophical Problems in Cosmology.” In BritishPhilosophy in the Mid-Century, edited by Cecil Alec Mace. London: Allen and Unwin, 1957.

With Felix Pirani and Ivor Robinson. “Gravitational Waves in General Relativity. III. Exact Plane Waves.” Proceedings of the Royal Society of London A 251 (1959): 519–533.

Assumption and Myth in Physical Science. Cambridge: Cambridge University Press, 1967.

Oral History Interview by David DeVorkin. 20 March 1978. Available at http://www.aip.org/history

“A Non-Believer Looks at Physics.” Physics Education 22 (1987): 280–283.

“The Cosmological Scene 1945–1952.” In Modern Cosmology inRetrospect, edited by Bruno Bertotti et al. Cambridge, U.K.: Cambridge University Press, 1990.

Science, Churchill & Me.The Autobiography of Hermann Bondi. London: Pergamon, 1990.

OTHER SOURCES

Kragh, Helge. Cosmology and Controversy. The HistoricalDevelopment of Two Theories of the Universe. Princeton, NJ: Princeton University Press, 1996.

Krasinski, Andrzej. “Editor’s Note: Spherically Symmetrical Models in General Relativity.” General Relativity and Gravitation 31 (1999): 1777–1781.

Mestel, Leon. “Obituary: Hermann Bondi (1919–2005).” Nature 437 (2005): 828.

Helge Kragh

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Hermann Bondi

Hermann Bondi

English astrophysicist Hermann Bondi (born 1919) made his career out of studying the universe and its origins. Although his "steady state" theory was eventually discarded in favor of the "big bang" theory of creation, Bondi opposed what he called the "arrogance of certainty" that discouraged scientists and others from questioning current theories of the universe's origins.

Born in Vienna, Austria, on November 1, 1919, Bondi grew up with Jewish parents who disagreed about the importance of religious observances. "My father didn't believe, but liked the religious observances and rituals as social cement. My mother was a nonbeliever who didn't like the forms," he said in an interview in Free Inquiry. He credited his attraction to humanism to this division between his parents.

By 1933, social strife in Austria was peaking; Nazi leader Adolf Hitler had come to power, and Bondi's country struggled to remain independent. The increasing prominence of the Nazi party in Austria led to two civil wars within six months. In his autobiography, Bondi recalled, "It was against this background that I threw myself into my mathematical physics and dreamt of going to live elsewhere." By 1936, Bondi realized that his academic potential could never be realized while still living in Austria, and he began to work toward acceptance at Cambridge University, in England. He moved to England to attend Trinity College, Cambridge, in 1937 and considered it his home ever since.

Despite his allegiance to England, anti-German and anti-Nazi fervor during World War II put all immigrants and foreigners under suspicion, and Bondi, despite his Jewish heritage, was not an exception. In May of 1940, he was interned along with most other foreigners in Britain, remaining confined on the Isle of Man. He was later transferred to Canada and while there he attempted to immigrate to the United States, where his family had moved to escape Nazi persecution. Because he had arrived in Canada as an internee, very nearly a prisoner of the British government, the United States refused to permit his immigration. He returned to the Isle of Man, still under internment, and was not released until August 1941.

Advanced the Steady-State Theory

Upon returning to Cambridge, Bondi worked with other astro-physicists who would be influential in his career: Thomas Gold and Fred Hoyle. In the Bulletin of the Institute of Mathematics and its Applications, Hoyle claimed that he persuaded both Bondi and Gold to become interested in astronomy. "Hermann was the most confident manipulator of equations I had ever seen," Hoyle recalled. Hoyle reported that Bondi had a very theoretical mind, which "led him at times of course to lose contact with physical reality."

In 1948, Gold and Bondi worked together to develop the steady-state theory of the creation of the universe, which held that the universe is ever-expanding, without a beginning and without an end. They supported the theory by appealing to the perfect cosmological principle, according to which the universe is the same at all points; their colleague Hoyle advanced the same theory according to physical laws. The theory addressed a crucial problem of astrophysics: How do the stars continually recede without disappearing altogether? Dr. Edwin Hubble had already demonstrated that the stars actually do recede, but no one had yet explained why their recession did not leave a void in the universe.

As Bondi explained in his book Cosmology, "Since the universe must be expanding, new matter must be continually created in order to keep the density constant." Cosmologists had previously believed that the expansion of the universe marked the beginning of time, and that as it expanded outward it was approaching the end of its existence. These views were based on the belief that there was a moment when everything was suddenly created together in a dense mass. According to Bondi and Gold's steady-state theory, creation was continuous: it did not occur suddenly, and it was still occurring. The spontaneous creation of matter, they maintained, was brought about by the interchangeability of matter and energy, as demonstrated by Albert Einstein.

While Bondi accepted that the steady-state theory was as yet only an unproven hypothesis, he argued that the theory would create more possibilities for scientific discovery than the belief that creation was an event in the past: "The hypothetical character of continual creation has been pointed out, but why is it more of a hypothesis to say that creation is taking place now than that it took place in the past? On the contrary, the hypothesis of continual creation is more fertile in that it answers more questions and yields more results, and results that are, at least in principle, observable. To push the entire question of creation into the past is to restrict science to a discussion of what happened after creation while forbidding it to examine creation itself. This is a counsel of despair to be taken only if everything else fails."

Failed Theory Led to Applied Science

Bondi later worked with R.A. Lyttleton of Imperial College, London. In 1959, the two proposed that the outward movement of planets and stars was the result of electrical "leaks" in space. The theory was founded on the assumption that galaxies have electrical charges on the surface, producing a force of repulsion that surpassed the force of gravitational attraction. As the New York Times reported, one of the strengths of the theories was its potential to explain the origin of cosmic rays. The equipment to test their theory, however, was not available, although physicists were not able to find a flaw in their logic.

A strong believer in scientists' responsibility to explain their work to society, Bondi began writing books for students and laypeople and appearing on BBC educational programs in Britain. Chief among his efforts was his attempt to explain the theory of relativity and the works of Isaac Newton and Albert Einstein. As John Durston explained in the preface to Bondi's book Relativity and Common Sense: A New Approach to Einstein, "Where previous writers have tried to develop relativity in opposition to the ideas of Isaac Newton, Professor Bondi derives relativity from Newtonian ideas. He pictures relativity as being neither revolutionary nor destructive of classical dynamics but rather as being an organic growth." Bondi felt strongly that all scientific advancement came from, as Newton had said, "standing on the shoulders of giants."

As Bondi was reflecting on the inevitable evolution of scientific theories, he saw his own steady-state theory threatened with obsolescence. In 1965, Arno Penzias and Robert Wilson discovered a radiation background in microwaves. This radiation, it was hypothesized, was background noise from the "big bang." Although the "big bang" theory has roots as early as 1922, the discovery of this radiation brought it back into prominence. Cambridge radio astronomer Martin Ryle told Newsweek, "I think after this few students will go into the steady-state theory in detail."

While Bondi's colleague, Hoyle, began revising the steady-state theory to take into account the new data, Bondi moved on to problems in applied science. In 1967, Bondi was appointed director of the European Space Research Organization. One of his main achievements while in office was the development of plans for phone and air-traffic satellites for Western Europe. These satellites would enable international phone connections that had previously required several hours to complete. Perhaps more important, they would increase air-traffic controllers knowledge of a plane's location, particularly as it began to "disappear" over the horizon of the Atlantic Ocean. In 1971, he became chief scientific advisor to Britain's Ministry of Defence, a post he maintained through 1977, when he became chief scientist for the Department of Energy. Bondi also served as chairman and chief executive of the Natural Environment Research Council (NERC), for which he traveled widely, attempting to generate interest and income for scientific research.

Returned to Cambridge

Throughout this time, Bondi continued his scholarly pursuits, publishing several papers and serving twice as president of the Institute of Mathematics and its Application. Staying active in his academic discipline enabled him to return to Cambridge when he retired from government service in 1980. He took the position of Master of Churchill College, Cambridge, from 1983-1990, and continued as a fellow there from 1990 onward.

Bondi was also an active advocate for humanism, signing in 1973 the "Humanist Manifesto II," in which 120 religious leaders, philosophers, scientists, and other thinkers declared, "Reason and intelligence are the most effective instruments that humankind possesses. There is no substitute: neither faith nor passion suffices in itself. The controlled use of scientific methods, which have transformed the nature and social sciences since the Renaissance, must be extended further in the solution of human problems. But reason must be tempered by humility, since no group has a monopoly on wisdom or virtue."

In 1992 Bondi became president of the British Humanist Association, through which he lobbied for tolerance of differing viewpoints and appreciation for the life-enhancing benefits of science. In particular, he stressed the importance of continuing to question the origins of life and of the universe. "I don't think answers to these question are the business of us humans," he said in Free Inquiry, "Trying to get there-asking questions, investigating, discussing, sharing views, sharing arguments-that is the important thing. The continuing quest is what we humans must work for, not achieving the final answer."

Further Reading

Bondi, Hermann, Cosmology, Cambridge University Press, 1952.

Bondi, Hermann, Relativity and Common Sense: A New Approach to Einstein, Heinemann, 1965.

Bondi, Hermann, Science, Churchill and Me: The Autobiography of Hermann Bondi, Pergamon, 1990.

Bulletin of the Institute of Mathematics and its Applications, December, 1989.

Free Inquiry, Spring 1992.

Newsweek, October 25, 1965.

New York Times, May 24, 1952; May 24, 1959; October 13, 1970; August 26, 1973.

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