Subrahmanyan
Chandrasekhar"He was admired not just for his enormous scientific achievements but for his deep and broad knowledge of literature and the arts." Diana Steele.
"There is total unanimity among astronomers that Chandrasekhar, as a mathematical astrophysicist, was the greatest of our generation." Martin Schwarzschild.
"Chandra's unique strength was his combination of a fundamental understanding of physical concepts and his phenomenal mathematical ability." Eugene Parker.
"Chandra cared for the personal and intellectual well-being of his students, trained them carefully and was willing to spend enormous amounts of time with them. He was a powerful role model for all who came in contact with him." Jeremiah Ostriker.
"He was the most intellectual of intellectuals, and the most tireless worker in science." Norman Lebovitz.
"In addition to his formidable scientific achievements, his friends and contemporaries remember him for his passionate interest in literature and classical music." Neeraja Sankaran.
Chandrasekhar's
special page at the Nobel Prize Internet Archive;
His
life, written by Diana Steele;
His
life, written by Neeraja Sankaran;
Ramanujan's
Influence on S.C. Chandrasekhar by Nitin Ingle;
Chandrasekhar
Photo Page.
Diploma in hand,
Chandrasekhar poses at Trinity College, Cambridge, in 1933.
Chandra came from a highly educated South Indian family. His father, C. S. Ayyar, was a civil servant, attaining a high position with the Indian railways. The Ayyars had three sons and five daughters of whom Chandra was the oldest son, born on 19 October 1910 in Lahore, then part of British India. In 1916 the family moved to Madras where Chandra grew up.
Chandra was a brilliant student. At 15, he entered Presidency College, the most prestigious in Madras; in 1927 he started their physics honours course, graduating in 1930 at the top of his class. He read far beyond the curriculum, for instance about Fermi statistics, where he was most intrigued by Ralph H. Fowler's work on the constitution of white dwarf stars. This subject inspired him to write his first scientific paper, "Compton Scattering and the New Statistics", which was published in the Proceedings of the Royal Society in 1928. Upon graduation, on the basis of this paper, he was accepted as a research student by Fowler at the University of Cambridge.
He left Bombay on a boat on 31 July 1930. On the voyage, after overcoming his seasickness, he remembered Fowler's paper and decided to combine it with his knowledge of special relativity theory. To his great surprise, he found that this combination predicted that white dwarfs could only exist up to a certain limiting mass which depended chiefly on fundamental constants such as h, G and the mass of the hydrogen atom; the mass was about 1.45 times the mass of the Sun. England's two leading astrophysicists, Eddington and Milne, could not believe this result, and neither of them would recommend Chandra's paper for publication by the Royal Society. So Chandra sent it to the Astrophysical Journal in America, which published it in March 1931.
Chandra worked hard as a research student, and after he had taken his Ph.D., he was (to his great surprise) elected a fellow of Trinity College. Now feeling relaxed and more confident, he returned to the problem of white dwarfs. By a more complete calculation, he confirmed his earlier result: there is an upper limit to the mass of a white dwarf. He was invited to give a talk on this subject at the Royal Astronomical Society in January 1935. But after his lecture, Eddington stood up and rejected Chandra's results, not by scientific argument but by ridiculing the combination of special relativity theory with quantum statistics. Chandra was devastated.
Of course, Eddington was wrong. But his resistance to Chandra's mass limit was understandable: his life's work had been to show that every star, whatever its mass, had a stable configuration. It was generally (and correctly) believed that white dwarfs were the end stage of stellar evolution, after their energy source was exhausted. Why should there be a limit to the mass of a star in its old age? Chandra appealed to physicists he knew - Rosenfeld, Bohr, Pauli. Unanimously, they decided that there was no flaw in his argument. But it took decades before the Chandrasekhar limit was accepted by the astrophysics community.
The paradox that 'normal' stars can exist with any mass whereas white dwarfs can only exist up to 1.45 solar masses is now understood as follows. Stars, in their evolution, go through a giant stage in which their radius may be hundreds of times larger than originally. In this stage, the atoms at the surface are not strongly held by gravity, while there is strong radiation pressure from the inside. Some atoms, especially hydrogen, are blown off and the star gradually loses mass. Theory shows that stars up to 8 solar masses lose mass in this manner, ending up below the Chandrasekhar limit. None of this was known in 1935.
The limit also affects stars heavier than 8 solar masses. Matter in their central core evolves to iron by successive nuclear reactions. At this point, no further nuclear energy can be obtained, just as in white dwarfs. When the iron core grows to the Chandrasekhar mass, it collapses by gravitation into a neutron star, and the rest of the star is expelled, giving a type II supernova. Some white dwarfs accrete matter from the outside, and when their mass has grown to the Chandra limit, they also become supernovae, in this case type Ia. Chandra's theory is basic to much modern astrophysics.
Chandra had to look for a more permanent position, and accepted an offer from Yerkes observatory, part of the University of Chicago with which he remained associated for the rest of his life - first at Yerkes, later in Fermi's Research Institute on the main university campus. Before starting work there in January 1937, he made an extensive visit to India and married Lalitha, his old friend from college days.
Chandra was an enthusiastic teacher who attracted students from all over the world. By the time of his retirement, he had guided over 50 students to their Ph.D.s. His own research covered nearly all branches of theoretical astrophysics; in his Nobel lecture he said that his life's work fell into seven periods. At the culmination of each period, Chandra published a book collecting the insights he had gained; each covers its subject very thoroughly. The Mathematical Theory of Black Holes (1983) is truly formidable.
Chandra was a great supporter of Gandhi. But during the Second World War, he felt victory over Nazi Germany was the most important goal. Seeing it as his duty to contribute to the American war effort he began in 1943 to work half-time at the Aberdeen Proving Ground on shock waves. Later, he was invited to join the Los Alamos laboratory, but because of lengthy clearance problems, this did not come to pass. His feeling of duty was despite many indignities that he and Lalitha suffered because of their dark skin. Nevertheless, they felt American, and in 1953 were naturalized as American citizens, feeling their life would continue to be in America. This made Chandra's father very unhappy. He had tried repeatedly to get a suitable position for Chandra in India. But even if he had found one, what could have replaced the intellectual stimulation in America?
A year earlier, in 1952, Chandra had felt another call of duty. He believed there should be a national journal for astrophysics. Up to that time, nearly every major department of astronomy had its own publication. By long negotiations, he persuaded the American Astronomical Society and the University of Chicago jointly to publish the Astrophysical Journal, and Chandra, at great sacrifice of his scientific output, became its editor. In his 19 years as editor, Chandra transformed the Astrophysical Journal from a local publication into a world leader. He was, in his own words, dictatorial, and many astrophysicists complained because their papers were rejected. To continue at least some research, he rigorously enforced office hours: if a scientist phoned after the appointed closing time, he would answer, "The office of the Astrophysical Journal is closed."
I was always impressed by the depth and sophistication of Chandra's mind, and its capacity for retention which showed in his writings and speeches on any topic. His style was informed by the British authors of the late nineteenth and early twentieth centuries, and by Shakespeare. It was a pleasure to listen to one of his talks. In addition to style, he had the most perfect upper-class English accent I have ever heard.
Chandra was a first-rate astrophysicist and a beautiful and warm human being. I am happy to have known him.
Chandrasekhar as a
young scholar at his desk.
Chandra was born on 19 October 1910. He graduated from Presidency College with a bachelor's degree in theoretical physics. While there he won an Indian government scholarship to Trinity College. He left India by ship on 31 July 1930.
As is well known, on his two-and-a-half week journey to England Chandra occupied himself by reformulating the statistical mechanics of the degenerate electron gas, recognizing that the higher quantum states are relativistic under the conditions in white dwarf stars. Contrary to his expectations he found that the electron pressure is limited to something of the order of hcN^(4/3), where N is the number density. The equivalent temperature is kT ~ hcN^(1/3). On the other hand, supporting a self-gravitating sphere of mass m against contraction requires a mean equivalent temperature of the order GmM/R, where M is the ionic mass associated with each electron. Because N ~ m/(MR^3) it follows that m must not exceed the order of (hc/G)^(3/2)/M^2, which turns out to be about 1.4 solar masses, now known as the "Chandrasekhar mass limit."
Later in the 1930s he made another important discovery at Cambridge: Fowler, Edward A. Milne and others were not able to grasp the reality and implication of this fundamental result. One of these others, Arthur Eddington, made no comment in private but publicly denounced Chandra's result, declaring, "I think there should be a law of nature to prevent a star from behaving in this absurd way." Later, Eddington argued that the Pauli exclusion principle could not be applied to relativistic systems. Léon Rosenfeld, Niels Bohr, Wolfgang Pauli and Paul A. M. Dirac upheld Chandra's result in private, but Eddington's cocksure faith in his own whims was unshaken, and the astronomical community largely accepted his authority. Thus arose the 50-year delay in Chandra's receiving the Nobel Prize in Physics in 1983.
Chandra received his PhD in December 1933, writing his thesis on rotating self-gravitating polytropes. But Eddington's authoritative wishful thinking on the mass limit of the white dwarf prevented Chandra from obtaining a proper position in England, while political bickering and favoritism blocked his chances in India. This situation led to his accepting an invitation from Otto Struve to join the faculty at the Yerkes Observatory of the University of Chicago.
In 1936 Chandra returned briefly to India to marry Lalitha Doraiswamy, with whom he had attended physics classes at Presidency College in Madras, and who was then working in the Bangalore laboratory of Chandra's uncle, Nobel laureate Chandrasekhara Venkata Raman.
Chandra and Lalitha arrived in Chicago at the end of 1936, and Chandra began his 58-year career at the University of Chicago, becoming Morton D. Hall Distinguished Service Professor in Astronomy and Astrophysics in 1952. They spent the first 27 years at the Yerkes Observatory and the last 31 years at the Chicago campus. Lalitha's broad interests and good judgment complemented Chandra's more severe outlook, and they got on well in the Chicago academic community.
Chandra developed his theoretical work on stellar interiors, including degenerate matter, into a treatise, An Introduction to the Study of Stellar Structure (University of Chicago Press, 1939), which still makes an excellent textbook on the basic properties of a star.
Chandra had also become interested in the gravitational frictional drag on a star passing through a tenuous cloud of stars as a key to understanding the ages of the globular clusters. He summarized this work in his 1943 book Principles of Stellar Dynamics (University of Chicago Press) and in his penetrating article on "Stochastic Problems in Physics and Astronomy," published in Reviews of Modern Physics in the same year. It is interesting to think of this work as the forerunner of plasma physics without the convenience of the Debye radius and without the inconvenience of a large-scale magnetic field.
Chandra continued his work on stellar interiors, with calculations on opacities and the basic theory of radiative transfer, doing fundamental work on the negative hydrogen ion as the principal cause of the opacity of hydrogen at stellar surface temperatures. His systematic formulation of the subject appeared in 1950 in his monumental Radiative Transfer (Oxford University Press). In the 1950s he investigated plasma physics and hydrodynamics and concentrated on the stability of a variety of magnetic fluid configurations. Much of his work in this area is to be found in Hydrodynamic and Hydromagnetic Stability (Clarendon Press, 1961), which has been a benchmark since its first appearance.
Chandra next directed his attention to the classical problem of the stability of rotating ellipsoidal figures. The results in the framework of Newtonian mechanics and gravitation were organized in the monograph Ellipsoidal Figures of Equilibrium (Yale University Press, 1968). This line of thought brought him to the gravitational theory of general relativity, with which he treated stellar pulsations, discovering the relativistic instability of radial oscillations of white dwarf stars, and the Chandrasekhar-Friedman-Schutz instability, which has ultimately developed into a mechanism for the gravitational wave emission of black holes. The dynamical properties of the rotating black hole were expounded by Chandra in The Mathematical Theory of Black Holes (Oxford University Press, 1983). His discoveries did not stop there. In his subsequent work with Valeria Ferrari on exact solutions of the equations of general relativity, the singularities that arise in interacting gravitational waves came to light. Chandra also developed the post-Newtonian approximation that has become the standard formal approach to calculating the gravitational waves from dynamical systems of massive particles and has served as the basis for the post-post-Newtonian formalism.
Chandra accomplished the difficult task of a formal general-relativistic treatment of the instability of radial stellar pulsations in recent work with Ferrari, and the final paper was essentially finished at the time of his death. The problem is of particular interest because without the emission of gravitational waves (that is, in Newtonian gravitation) the system is stable unless some other form of dissipation is introduced. In his last years Chandra became increasingly interested in Newton's Principia. He published his review of Newton's work in a monograph, Newton's Principia for the Common Reader (Oxford University Press), which appeared just two months before his death.
Chandra's book Truth and Beauty (University of Chicago Press), published in 1987, contains a number of essays, including his well-known Ryerson Lecture, "Shakespeare, Newton and Beethoven," which is only one of his explorations of the motivations, ambitions and aesthetic rewards of the artist and the scientist.
Chandra served as editor of the Astrophysical Journal from 1952 to 1971, transforming it from a more or less private journal of the University of Chicago into the national journal of the American Astronomical Society, still published by the University of Chicago Press.
Chandra maintained uncompromising standards of integrity and excellence for his own research, for his editing and for his students, associates and acquaintances. It did not always foster the smoothest personal relations, because there were occasional misunderstandings on both sides. But it was an integral part of Chandra's scientific prowess, and his friends and acquaintances respected him for it.
In spite of the difficulties that Eddington's mulish attacks had created for him, Chandra ranked Eddington next to Karl Schwarzschild as the greatest astronomer of his time when he presented an obituary address for Eddington in 1944.
Chandra's own death on 21 August 1995 at the age of almost 85 marked the passing of an era in which physicists first reached inward to understand the atom and the fundamental particles and outward to embrace the stars. Chandra never wavered in his pursuit of the physics of the stellar object in its diverse forms.
More on Chandrasekhar in:
Kameshwar C. Wali, "Chandra: A Biography of S. Chandrasekhar.", University of Chicago Press, 1990 .
Kameshwar C. Wali, "Chandrasekhar vs. Eddington - an unanticipated confrontation", Physics Today (October) pp. 33-40 (1982).
S. Chandrasekhar, "Some historical notes", American Journal of Physics, 37 pp. 577-584 (1969).
But studying Chandrasekhar's writings is the best way to know him.
Subrahmanyan Chandrasekhar, a winner of the 1983 Nobel Prize in physics whose theories about the evolution of stars led to the concept of black holes, died of heart failure on August 21 at the University of Chicago Hospitals. He was 84 years old.
STELLAR: Subrahmanyan Chandrasekhar
While still a student in the 1930s, Chandrasekhar developed a theory that challenged the prevalent notion of the formation of 'white dwarfs.' Most astrophysicists in those times believed that after burning up their fuel, stars collapsed into planet-sized entities that they referred to as white dwarfs. However, through his calculations, Chandrasekhar proposed that only stars equivalent in size to the sun became dwarfs. If the mass of the star were greater than 1.4 times the sun, he claimed, the star would continue to collapse into an object of enormous density. Although he was publicly ridiculed for this -- especially by his idol, the British astrophysicist Sir Arthur Eddington -- his theories form the basis for modern astrophysics: The critical mass he predicted is called the 'Chandrasekhar limit,' and the objects of infinite density are widely referred to as 'black holes.' This work led to his Nobel Prize nearly a half-century later.
Colleagues remember Chandrasekhar as a dedicated scientist and teacher. "One thing that stands out in my mind is that he was adamant that the highest standards be applied to science. He had very little patience for fuzzy-mindedness," Parker recalls.
At the same time, he adds, the astrophysicist was always open to entertaining speculation, relating a personal encounter regarding the publication of a paper -- E. Parker, Astrophysical Journal, 128:664, 1958. "The paper was about solar winds -- offering both physical and mathematical evidence for the occurrence of the phenomenon," Parker recounts. "It had been turned down by two very well-respected reviewers -- I never found out who they were -- and Chandra, who was then the editor of the journal, came and asked me,'Are you sure you want to publish this?'
"When I pointed out that the reviewers did not offer valid arguments disproving my hypotheses, Chandra went ahead and printed it, although he himself was politely skeptical about my theory," he says. "A lot of publishers could have just taken the easy way out and [gone] with the reviewers. But Chandra was a very tough-minded guy -- he always did exactly what was called for."
Born in Lahore in colonial India in 1910, Chandrasekhar was the nephew of India's only other physics Nobelist (1930), Chandrasekhara Venkata Raman. After receiving a B.A. in mathematics and physics from Presidency College in Madras, India, in 1930, he went to study in England on a government scholarship, obtaining a Ph.D. in physics from Cambridge in 1933. He moved to the University of Chicago in 1937 and remained there until his death. He became a U.S. citizen in 1958.
Chandrasekhar made his peace with Eddington, who promoted his 1944 election to the Royal Society. In 1962 Chandrasekhar went on to receive the society's Royal Medal.
In 1966 he was the recipient of the National Medal of Science. He wrote several books on various areas of astrophysics and physics, his most recent, titled Newton's Principia for the Common Reader, published just this summer by the Clarendon Press of Oxford University. In addition to his formidable scientific achievements, his friends and contemporaries remember him for his passionate interest in literature and classical music.
-- Neeraja Sankaran
In 1936, Chandrasekhar moved from England to the United States, where he became a naturalized citizen in 1953. His academic career in this country has centered on the University of Chicago, where he accepted a faculty position in 1937. Although he began his professional career working on the structure and evolution of stars, Chandrasekhar's interests have carried him into a number of areas of research culminating in his sharing of the 1983 Nobel Prize in Physics with William A. Fowler of the California Institute of Technology. As he wrote in his biographical note for the Nobel Foundation, "...my scientific work has followed a certain pattern motivated, principally, by a quest after perspectives." This "quest after perspectives" led to his publication of six books and numerous journal papers, each of which has been recognized as definitive in its field: An Introduction to the Study of Stellar Structure (1939), Principles of Stellar Dynamics (1943), Radiative Transfer (1950), Hydrodynamic and Hydromagnetic Stability (1961), Ellipsoidal Figures of Equilibrium (1968), and The Mathematical Theory of Black Holes (1983). Few scientists have matched his consistently high level of scientific research, beginning in his twenties and continuing into his seventies--a span of 50 years.
Credit: University of
Chicago Press, S. Chandrasekhar
Copyright: 1989 by The University of Chicago. All rights reserved.
Used by permission.
