| Subrahmanyan
Chandrasekhar |
 |
October 13, 1910 — August
21, 1995
Subrahmanyan Chandrasekhar was born into
a free-thinking, Tamil-speaking Brahmin family in Lahore, India. He
was preceded into the world by two sisters and followed by three
brothers and four sisters. His mother Sitalakshmi had only a few
years of formal education, in keeping with tradition, and a measure
of her intellectual strength can be appreciated from her successful
translation of Ibsen and Tolstoy into Tamil. His father C. S. Ayyar
was a dynamic individual who rose to the top of the Indian Civil
Service. It is not without interest that his paternal uncle Sir C. V.
Raman was awarded a Nobel Prize in 1930 for the discovery of the
Raman effect, providing direct demonstration of quantum effects in
the scattering of light from molecules.
Education
began at home with Sitalakshmi giving instruction in Tamil and
English, while C. S. Ayyar taught his children English and arithmetic
before departing for work in the morning and upon returning in the
evening. The reader is referred to the excellent biography Chandra, A
Biography of S. Chandrasekhar (University of Chicago Press, 1991) by
Prof. Kameshwar C. Wali for an account of this remarkable family and
the course of the third child through his distinguished career in
science. Chandra is the name by which S. Chandrasekhar is universally
known throughout the scientific world. Chandra's life was guided by a
dedication to science that carried him out of his native culture to
the alien culture of foreign shores. The crosscurrents that he
navigated successfully, if not always happily, provide a fascinating
tale. He was the foremost theoretical astrophysicist of his time, to
paraphrase his own accounting of Sir Arthur Eddington.
The family moved to Madras in 1918 as C. S. Ayyar rose to deputy
accountant general. Chandra and his brothers had private tutors then,
with Chandra going to a regular school in 1921. His second year in
school introduced algebra and geometry, which so attracted him that
he worked his way through the textbooks the summer before the start
of school.
Chandra entered Presidency College in
Madras in 1925, studying physics, mathematics, chemistry, Sanskrit,
and English. He found a growing liking for physics and mathematics
and an ongoing attraction for English literature. One can assume that
his fascination with English literature contributed to his own lucid
and impeccable writing style.
Chandra was inspired
by the mathematical accomplishments of S. Ramanujan, who had gone to
England and distinguished himself among the distinguished Cambridge
mathematicians until his early death in 1920. Chandra aspired to take
mathematics honors, whereas his father saw the Indian Civil Service
as the outstanding opportunity for a bright young man. Mathematics
seemed poor preparation for the Civil Service. Sitalakshmi supported
Chandra with the philosophy that one does best what one really likes
to do. Chandra compromised with physics honors, which placated his
father in view of the outstanding success of Sir C. V. Raman.
On his own initiative Chandra read Arnold Sommerfeld's book
Atomic Structures and Spectral Lines and attended lectures in
mathematics. His physics professors noticed that he was learning
physics largely through independent reading and provided him with the
freedom to attend mathematics lectures. In the autumn of 1928
Sommerfeld lectured at Presidency College. Chandra made it a point to
meet Sommerfeld and was taken aback to learn that the old Bohr
quantum mechanics, on which Sommerfeld's book was based, was
superseded by the wave mechanics of Schroedinger, Heisenberg, Dirac,
Pauli, et al., and that the Pauli exclusion principle replaced
Boltzmann statistics with Fermi-Dirac statistics. Sommerfeld had
already applied the new theory to electrons in metals and kindly
provided Chandra with galley proofs of his paper. Chandra launched
into an intensive study of the new quantum mechanics and statistics
and wrote his first professional research paper "The Compton
scattering and the new statistics" (1929). In January 1929 he
communicated this work to Prof. R. H. Fowler at Cambridge for
publication in the Proceedings of the Royal Society of London. The
name Fowler suggested itself because Fowler had applied the new
statistics to collapsed stars (i. e., white dwarfs). Fowler was an
open-minded and generous individual who perceived the merit of
Chandra's paper, which he duly communicated to the Royal Society.
This contact was to play a crucial role a year later when Chandra
arrived in England.
Heisenberg lectured at
Presidency College in October 1929 and Chandra had the opportunity to
carry on extensive discussion with him at the time. Then Meghnad Saha
at Allahabad, known for the statistical mechanics that provided the
interpretation of stellar spectra, invited Chandra for discussions of
Chandra's paper in the Proceedings of the Royal Society of London.
Wali, in his biography, contrasts this early appreciation of
Chandra's work by the scientific community with the class snobbery of
the British Raj on the personal level.
Final
examinations at Presidency College came in March 1930 and Chandra
established a record score. In February Chandra was informed that a
special Government of India scholarship was to be offered to him to
pursue study and research in England for three years. When the
scholarship was announced publicly, Chandra experienced resentment
from fellow Indians who perceived him as abandoning his country and
his legacy. Worse, it was becoming clear that Sitalakshmi was
terminally ill and, if Chandra went to England, he would not see her
again. True to form Sitalakshmi decided the issue by declaring that
Chandra was born for the world and not just for her.
Chandra informed the authorities that he wished to use his government
scholarship to study and carry on research with R. H. Fowler at
Cambridge. The Office of the High Commissioner of India proceeded
with the arrangements. Chandra departed Bombay on July 31, 1930,
bound for Venice, from where he traveled by rail to London, arriving
August 19. He undertook the journey in his personal pursuit of
science, and that journey was culturally irreversible, a departure
from home from which he never really returned.
It
is well known that Chandra spent his time on shipboard working out
the statistical mechanics of the degenerate electron gas in white
dwarf stars, appreciating, as Fowler had not, that the upper levels
of the degenerate electron gas are relativistic. Since it is the
upper levels that are affected by changes in density and temperature,
it follows that a density change and pressure change p are related by
p/p = 4/3 rather than the nonrelativistic value 5/3 employed earlier
by Fowler. The value 4/3 meant that the pressure supporting the star
against gravity grows no faster than the increasing gravitational
force as the star contracts, with the result that there is a limiting
mass above which the internal pressure of the white dwarf cannot
support the star against collapse. This is in contrast with the
familiar nonrelativistic situation where the pressure increases more
rapidly than the gravitational forces so that sufficient contraction
must ultimately provide a sufficient pressure to block further
contraction. The limiting mass was clearly of the order of the mass
M. of the Sun (2 x 1033 g). A precise value would require detailed
calculations of the interior structure of the star with the precise
value of p/p for intermediate levels as well as the upper fully
relativistic levels at each radius in the star. But the implication
was clear. A massive star, of which there are many, cannot fade out
as a white dwarf once its internal energy source is exhausted.
Instead it shrinks without limit, always too hot to become completely
degenerate, and disappears when the gravitational field above its
surface becomes so strong that light cannot escape. In modern
language, the massive star eventually becomes a black hole. The
reasoning was straightforward and the conclusion was startling. The
repercussions that ultimately followed his discovery served to push
Chandra farther into the obscure and lonely byways of science in a
foreign Western society and ever more distant from his cultural
origins.
Upon arrival in London Chandra discovered
that the Office of the Director of Public Instruction in Madras and
the High Commissioner of India in London had thoroughly bungled his
admission to Cambridge. What was more, the secretary for the high
commissioner's office had not the least interest in correcting the
mistake and was openly rude in his assertion of that fact. Chandra
was saved only by the eventual firm intervention of Fowler, who was
vacationing in Ireland at the time of Chandra's arrival in London.
The consequences of Chandra's first research paper were more far
reaching than anyone could have imagined.
Chandra
took up his studies at Cambridge and spent a lonely but productive
year in intensive study and research. Sitalakshmi died on May 21,
1931, adding grief to his loneliness. Chandra was introduced to the
monthly meetings of the Royal Astronomical Society and became
acquainted with E. A. Milne and P. A. M. Dirac. Chandra devoted his
research efforts to calculating opacities and applying his results to
the construction of an improved model for the limiting mass of the
degenerate star. Milne was enthusiastic about the work, but it turned
out later that his enthusiasm was based more on his rivalry with A.
S. Eddington than on an appreciation of the scientific merits.
The year of intensive study at Cambridge moved Chandra to
look for a change of scenery, and at the invitation of Max Born he
spent the summer of 1931 at Born's institute at Gottingen. There he
became acquainted with Ludwig Biermann, Edward Teller, Leon
Brillouin, and Werner Heisenberg. Back at Cambridge in the autumn
Chandra continued his work on atomic absorption coefficients and mean
opacities, but with a growing sense of frustration from his feeling
that he was abandoning mathematics through his pursuit of physics and
abandoning pure physics through his pursuit of astrophysics. Chandra
was invited to present his results on model stellar photospheres at
the January 1932 meeting of the Royal Astronomical Society (RAS) and
was complimented by both Milne and Eddington following the
presentation.
Chandra's feeling of frustration
with his "peripheral science" led to his spending his third year at
Bohr's institute in Copenhagen. He adapted readily to the informal
atmosphere and became acquainted with Victor Weisskopf, Leon
Rosenfeld, M. Debrueck, H. Kopferman, and others. During the time in
Copenhagen Chandra succeeded in convincing himself that his real
strength lay in developing and expounding the implications of the
basic physical laws of nature as distinct from the pursuit of new
laws of nature. He found an interested and appreciative audience in
the physics community for his work on degenerate stars. Chandra was
invited to the University of Liege to lecture on his work, following
which he was presented with a bronze medal. The overall experience of
the year was to ease his mind and set him firmly on a path in
theoretical astrophysics.
Chandra finished the
year with four papers on rotating self-gravitating polytropes, which
became his Ph.D. thesis. His government scholarship ran out in August
1933 and the question was what to do next. It was clear that there
were no opportunities in India unless he rode on the coattails of his
uncle Raman, which he was loathe to do. Fortunately he won one of the
highly competitive appointments as a fellow of Trinity College, which
ran for four years. Milne nominated Chandra for fellow of the RAS,
and the future was clear for the immediate years at Cambridge. At the
monthly meetings in Burlington House Chandra and such contemporaries
as William McCrea generally sat in the back row, but became
acquainted with some of the denizens of the front row (e.g., Sir
James Jeans, Sir Arthur Eddington, Sir Frank Dyson, and such
international visitors as Henry Norris Russell and Harlow Shapley).
Chandra spent four weeks in the Soviet Union in the summer
of 1934 at the invitation of B. P. Gerasimovic, meeting L. D. Landau
and V. A. Ambartsumian, along with many other enthusiastic young men.
Unhappily only Landau and Ambartsumian survived the massive purges
that were soon to follow. Ambartsumian grasped the significance of
Chandra's work on dwarf stars and suggested that it was worth working
out exactly (i.e., by direct radial integration of the exact
equations, using the complete pressure-density relation). This moved
Chandra to tackle that immense problem upon his return to Cambridge.
The work was accomplished with the aid of a hand calculator
and was completed by the end of 1934. He submitted his results for
presentation at the January 1935 meeting of the RAS. Eddington had
taken an interest in the work through the autumn, often dropping by
Chandra's room to see how things were progressing, but never saying a
word to Chandra about his own private thoughts. Eddington suggested
to the secretary of the RAS that Chandra's work merited double the
usual fifteen minutes for presentation and then set himself up to
present a paper with the title "Relativistic degeneracy" immediately
following. Eddington refused to divulge the nature of his
presentation beforehand. McCrea notes in his obituary for Chandra
that Eddington began by pointing out that Chandra's calculations were
entirely correct based on the relativistic degenerate electron gas.
Eddington then noted that the result predicted that a white dwarf
with mass in excess of the critical value (~ 1.4 M.) would continue
to radiate and shrink until it disappeared. Then Eddington went on to
declare that stars do not behave in that way, and Chandra's
calculations showed only that the theory of relativistic degeneracy
is incorrect. Later he asserted that the Pauli exclusion principle
does not apply to relativistic electrons. One might have asked
Eddington how he knew that stars do not behave in that way, but
Eddington was so formidable and influential a person that no one did,
apparently. Egos were the same then as now, and one has only to read
Eddington's remarkable monograph Fundamental Theory (Cambridge
University Press, 1944) to realize that he was coming around to the
idea that he could deduce the physical nature of the universe from
his own personal declarations.
The physicists,
Chandra's young contemporaries (e.g., Pauli, Rosenfeld, Dirac, and
others), considered Eddington's assertions to be nonsense, but
Eddington moved in a different world. R. H. Fowler and H. N. Russell
did not voice the essential points in opposition to Eddington's
assertions, evidently intimidated by Eddington's preeminence.
Russell, for instance, refused to allow Chandra to say a few words in
response to Eddington's hour long exposition of his personal views at
the meeting of the International Astronomical Union (IAU) in Paris in
July 1935. Chandra managed a brief comment at the "International
Colloquium on Astrophysics: Novae and White Dwarfs" in Paris in July
1939, but Russell quickly closed the session before a discussion
could proceed.
The question of returning to India
was raised by C. S. Ayyar, but Chandra found himself increasingly out
of sympathy with the political nature of academia in India. Then
Harlow Shapley invited Chandra to visit the Harvard Observatory.
Chandra arrived in Boston on December 8, 1935. He enjoyed the
friendly atmosphere but was unhappy with the informality after the
tightly structured society at Cambridge. He became acquainted with
Fred Whipple, Gerard Kuiper, Jerry Mulders, and others. Shapley liked
Chandra's lectures so well that he nominated Chandra for election to
the Harvard Society of Fellows. Then Otto Struve invited Chandra to
visit the Yerkes Observatory of the University of Chicago, followed
by an offer of a position as research associate for a year with the
expectation that it would become a tenure track appointment in a
year. The formal offer came from the office of Chancellor Robert
Maynard Hutchins. By the end of the month Chandra had returned to
England.
The Eddington factor had the effect of
closing the doors in England, and India offered no acceptable
situation. So Chandra accepted Struve's offer, much to the disgust of
his father who saw his son receding farther into the mists of foreign
culture.
Since his departure from India in July
1930 Chandra had corresponded occasionally with Lalitha Doraiswamy
who had been a fellow student in physics at Presidency College. She
was in Bangalore in 1935 working in Raman's laboratory. They were
both aware that they did not know each other very well, and Chandra
had fretted over whether a marriage relationship might interfere with
his pursuit of science. Chandra returned to India for a visit in
August 1936 and wrote to Lalitha that he would be at Madras. She took
the train to Madras to meet him and his misgivings vanished when they
met after six years of geographical separation. They were married
September 11, 1936.
Chandra and Lalitha spent a
month in Cambridge on their way to Boston and then the Yerkes
Observatory. Struve contacted the legal counsel of the University of
Chicago to arrange a visa for Chandra as a missionary, for otherwise
there was no quota for Indians to enter the United States. They
arrived at the Yerkes Observatory on Williams Bay on Lake Geneva in
Wisconsin on December 21, 1936. They stayed a few days with the
Kuipers until their house was ready, and the cold Wisconsin weather
was offset by the friendliness of the atmosphere at the observatory.
Lalitha recognized the importance of Chandra's
single-minded pursuit of science, and she supported him at the
expense of her own career. She was active in the American Association
of University Women and her outgoing sociability complemented
Chandra's more austere view of life so that they got on very well in
their new surroundings.
The University of Chicago
provided Chandra with his scientific home for the next fifty-nine
years, but there were difficult moments. Chancellor Hutchins
intervened on more than one occasion to smooth the way. For instance,
in 1938 Struve organized a course in astronomy on the campus of the
university to be taught by members of the Yerkes Observatory. However
Henry G. Gale, dean of physical sciences, vetoed Chandra's
participation, evidently on grounds of skin color. When the problem
was referred to Hutchins he said, "By all means have Mr.
Chandrasekhar teach." At that point it became clear why the original
offer of a position had come from the chancellor's office rather than
through the dean.
In 1946 Princeton honored
Chandra by offering him the office and position vacated by the
retirement of Henry Norris Russell with a salary approximately double
Chandra's salary at Chicago. Chandra was inclined to accept. Hutchins
matched the Princeton salary and asked Chandra to come by his office
to discuss the matter. In the course of the discussion Hutchins
remarked that, if conditions for Chandra's research were better at
Princeton, then he would not attempt to dissuade Chandra from
leaving. When Chandra responded that he did not think so, Hutchins
noted that Chicago could not offer Chandra the honor of succeeding a
Henry Norris Russell because Chicago had no Russell. Then he asked
Chandra for the name of the person who had succeeded to Kelvin's
chair at the University of Glasgow. Chandra replied that he had no
idea; to which Hutchins replied, "Well, there you are." Chandra
declined the Princeton offer and Hutchins remarked on more than one
occasion that acquiring Chandra for the University of Chicago was one
of his major accomplishments as chancellor.
The
course of Chandra's research is perhaps best summarized by the
monographs that he wrote as he completed each phase of his work. An
Introduction to the Study of Stellar Structure (1939) contains his
development of the theory of stellar structure, including his work on
degenerate stars and the mass limit for white dwarfs, and still makes
an excellent textbook on the subject. The Principles of Stellar
Dynamics (1943) and "Stochastic problems in physics and astronomy"
(1943) outline his development of the theory of the dynamics of the
motions of stars in the presence of many other stars, showing the
frictional drag exerted by neighboring stars and setting up the basic
theory for the evolution of clusters of stars. Radiative Transfer
(1950) contains his systematic development of the radiative flow of
energy in stellar interiors and photospheres including his work on
the negative hydrogen ion that dominates the opacity at the surface
of a star.
In 1952 the Department of Astronomy
revamped its graduate curriculum to keep up with the rapid
development in the fields of atomic physics, stellar atmospheres, and
stellar evolution. Chandra had been offering a repertoire of basic
courses in stellar structure and radiative transfer. These courses,
based in large part on his own fundamental work, provided excellent
background for the theoretical students, but were heavy going for the
observational students and lacked up-to-date information needed by
both groups of students. Chandra was alienated by the revision and
Enrico Fermi seized the opportunity to invite Chandra to become a
member of the Department of Physics and the Institute for Nuclear
Studies (now the Enrico Fermi Institute). Chandra accepted the
invitation and henceforth confined his teaching principally to the
Department of Physics, commuting from Yerkes to Chicago two days a
week to teach. In 1964 Chandra moved permanently to the Chicago
campus, the transition catalyzed by John Simpson's offer of a
spacious corner office in the newly constructed Laboratory for
Astrophysics and Space Research.
It is ironic that
1952 was also the year Chandra took up the onerous task of managing
editor of the Astrophysical Journal. He carried on the
responsibilities in his own style, personally attending to the
problems of production, refereeing, and politics within the
community. The editing was managed with the help of a secretary and
an editorial assistant at the University of Chicago Press. Under
Chandra's leadership the journal developed into the leading
international journal in astrophysics. The journal was in reality
privately owned by the University of Chicago. Chandra was its heart
and soul, and Chandra realized the unstable character of the
situation. In 1967 he set in motion a reorganization that would
transfer the primary responsibility to the American Astronomical
Society (AAS), although the actual production was to continue at the
University of Chicago Press. The rapid expansion of the journal from
six issues a year to two large issues a month made it increasingly
difficult for a single editor to handle, particularly with Chandra's
establishment of the Astrophysical Journal Letters in 1967. So
Chandra proposed that there be associate editors to assist the
managing editor. To make a long story short, the new order of things
was approved by the American Astronomical Society, and Chandra was
able to pass on his enormous burden to the new team in 1971. It is
remarkable that during his years as editor Chandra carried on his
scientific research at a rate not noticeably diminished at the same
time that he taught his quota of courses in the Department of
Physics. It is an example of the extraordinary feats that can be
accomplished through dedication and self-discipline to the exclusion
of nearly everything else in one's life. His retirement from the
position as editor was a great relief to Chandra. He had never
intended that the burden should have continued for so long.
Chandra and Lalitha were faced with the question of U.S.
citizenship, and after thinking about it for a time came to the
conclusion that it was the only realistic choice. It was a big step
away from their origins, but to do otherwise would have ignored the
fact of their permanent commitment to a life in the United States. So
in 1953 they became naturalized citizens. Lalitha's careful
explanation of the evolution of their thinking did little to assuage
the bitter feelings of C. S. Ayyar who saw the move only as a
betrayal of their cultural origins rather than an inevitable
evolution in their circumstances. Following citizenship Chandra was
elected to the National Academy of Sciences in 1955.
During Chandra's early years as editor, the field of plasma physics
and the confinement of ionized gas in magnetic fields in the
laboratory was coming into prominence, with the hope, still
unrealized today, of producing available power through the fusion of
hydrogen into helium. At the same time it was being appreciated that
the physics of fully ionized gases (i.e., plasmas) is the basis for
the dynamical behavior of stellar interiors, atmospheres, and the
interstellar gas. Plasma conditions range all the way from the
tenuous, essentially collisionless gases in space to the incredibly
dense plasma in the central regions of a star. Chandra was attracted
by the challenge of the unknown. He expounded the existing theory of
collisionless plasma in a course on the foundations of plasma physics
based on the standard free-particle approach and the collisionless
Boltzmann equation. S. K. Trehan put together a book Plasma Physics
(University of Chicago Press, 1960) based on the notes from that
course. In collaboration with A. N. Kaufman and K. M. Watson Chandra
carried through the immense calculation of the dynamical stability of
the collisionless plasma confined in an axial magnetic field. At the
same time Chandra entered into an extensive study of the dynamical
stability of fluids in various configurations, including the presence
of magnetic fields and rotation of the entire system. His
contributions are summarized in his monograph Hydrodynamic and
Hydromagnetic Stability (1961).
From there Chandra
took up the classical and unfinished problem of the dynamics of
rotating, self-gravitating spheroids of homogeneous incompressible
fluids. The problem had been initiated by Newton in connection with
the oblateness of Earth and carried on from there by such great names
as Maclaurin, Reimann, Dedekind, Jacobi, Dirichlet, et al. Chandra
reopened the unfinished problems with the tensor virial equations
whose great power had not been appreciated up to that time. The
results of that work appear in his monograph Ellipsoidal Figures of
Equilibrium (1969).
The work on selfgravitating
objects soon brought Chandra to the doorstep of general relativity as
the basic theory of gravity. His efforts in that field led to
development of the Chandrasekhar-Friedman-Schultz instability, which
became a source of gravitational radiation from black holes.
Extensive investigation of the Kerr metric and the rotating black
hole led to the monograph The Mathematical Theory of Black Holes
(1983). Chandra also developed the post-Newtonian approximation for
treating the field equations of general relativity. It is now the
means for calculating the gravitational radiation from multiple star
systems, etc. He went on to work out a variety of exact solutions to
the equations of general relativity in collaboration with B. C.
Xanthopoulos and V. Ferrari, showing some of the remarkable
singularities that turn up in the interaction of gravitational waves
and at the apex of the conical space solutions. One of the more
curious discoveries was that the radial pulsations of a star, which
are known from Newtonian gravitation to exhibit overstability in the
presence of dissipation (e.g., viscosity) become unstable in general
relativity through the energy loss represented by the emission of
gravitational waves. Thus the star without internal dissipation is
stable according to Newtonian theory, but unstable in the context of
general relativity.
As a brief aside it is
interesting to note that in 1982 Chandra was invited to lecture on
Sir Arthur Eddington at the celebration at Cambridge of the hundredth
anniversary of his birth. The lectures are published in the small
book Eddington, the Most Distinguished Astrophysicist of His Time
(1983). The lectures emphasize the remarkable insights of Eddington
into stellar structure and his early recognition of the implications
of Einstein's general relativity. Chandra's reflections on
Eddington's assertions on electron degeneracy and the Pauli exclusion
principle are of particular interest.
By 1990
Chandra had developed a growing interest and admiration for the work
of Sir Isaac Newton, and over the next several years he constructed a
detailed and critical review of Newton's Principia. The results of
this effort are published as Newton's Principia for the Common Reader
(1995). This was the first time that a world class physicist
undertook a thorough reading and critical commentary of the
Principia, dispelling such perpetuated notions that Newton's theory
of the perturbations of the orbit of the Moon is in error, or that
some of his diagrams were incorrectly drawn.
Chandra's book Truth and Beauty (1987) shows an entirely different
side of his thinking. It includes his Ryerson Lecture "Shakespeare,
Newton, and Beethoven" in which he explored and compared the
motivations and feelings involved in the creation of science and art.
Chandra's scientific papers are collected in seven volumes
under the title Selected Papers, S. Chandrasekhar (1989-96). They
complement the monographs listed above and provide a more detailed
historical picture of the day-by-day development of his thinking.
Chandra attached great importance to training Ph.D.
students. He saw them clearly as the future of astrophysics when the
present generation of working scientists has passed into retirement
and beyond. Struve had assigned him the responsibility for the weekly
colloquium, held on Monday afternoons, and Chandra saw to it that the
graduate students were in regular attendance. The Yerkes faculty,
graduate students, and visitors presented their work at appropriate
times, and Chandra gave each hundredth colloquium himself, as well as
many in between. The count of weekly colloquia passed 500 before
Chandra moved to the campus. He also conducted seminars on Monday
evenings for the edification of the graduate students, who took turns
reporting on interesting papers that had appeared in the literature.
Chandra supervised forty-six known Ph.D. research students, many of
whom have become prominent in the field of astrophysics, and not a
few of whom are members of the National Academy of Sciences. Chandra
was a stern taskmaster who insisted on rigorous training and
research. The graduate courses in theoretical astrophysics taught at
Yerkes by Chandra were the usual preparation, until the early
fifties. After that most of Chandra's students came through the
Department of Physics. Once a student successfully completed the
Ph.D., Chandra gave his full support in getting the student
established in the scientific community. In fact Chandra's support
was not limited to his students alone. He appeared at critical
moments in the career of this writer, as with others as well.
It is no surprise, of course, to learn that Chandra was
awarded many honorary degrees and medals. He was elected a fellow of
the Royal Society in 1944, which awarded him the Bruce Medal in 1952.
The Royal Astronomical Society awarded him its Gold Medal in 1953. He
was awarded the National Medal of Science by President Lyndon Johnson
in 1967. The fundamental nature of Chandra's mass limit for
degenerate stars has come to be appreciated in the astronomy and
physics communities, recognizing that it is perhaps the most direct
and striking example of the effect of quantum physics on macroscopic
bodies. Chandra was awarded a Nobel Prize by King Carl Gustav in 1983
in recognition of his work of fifty years before. On the other hand
it must be appreciated that Chandra's work on radiative transfer,
stellar dynamics, dynamical stability of fluids, plasmas and
selfgravitating bodies, and gravitational theory collectively
represent a much larger contribution to physics and astrophysics than
the more spectacular mass limit.
Chandra's death
in 1995 heralded the end of the era that developed the basic physics
of the star. He was the most prolific and wide ranging of those who
applied hard physics to astronomical problems.
I
EXPRESS MY APPRECIATION to D. E. Osterbrock for his careful reading
of the manuscript and several important suggestions and corrections
from his own association with Chandra over the years.
SELECTED BIBLIOGRAPHY
1929 : The
Compton scattering and the new statistics. Proc. R. Soc. London, Ser.
A 125:231-37.
1939 : An Introduction to the Study of
Stellar Structure. Chicago: University of Chicago Press.
1943 : The Principles of Stellar Dynamics. Chicago: University
of Chicago Press.
Stochastic problems in physics and
astronomy. Rev. Mod. Phys. 15:1-89.
1950 : Radiative
Transfer. Oxford: Clarendon Press.
1958 : With A. N.
Kaufman and K. M. Watson. The stability of the pinch. Proc. R. Soc.
London, Ser. A 245:435-55.
1960 : Plasma physics. A
course given by S. Chandrasekhar at the University of Chicago. Notes
compiled by S. K. Trehan. Chicago: University of Chicago Press.
1961 : Hydrodynamic and Hydromagnetic Stability. Oxford:
Clarendon Press.
1969 : Ellipsoidal Figures of
Equilibrium. New Haven. Yale University Press.
1983 :
The Mathematical Theory of Black Holes. Oxford: Clarendon Press.
Eddington, The Most Distinguished Astrophysicist of His Time.
Cambridge: Cambridge University Press.
1984 : On
Stars, Their Evolution and Their Stability. Nobel lecture. Stockholm:
Nobel Foundation.
1987 : Truth and Beauty. Chicago:
University of Chicago Press.
With B. C. Xanthopoulos. On
colliding waves that develop time-like singularities: A new class of
solutions of the Einstein-Maxwell equations, Proc. R. Soc. London,
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1989-1996 : Selected Papers, S.
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