Subrahmanyan Chandrasekhar

Birth and Death

Subrahmanyan Chandrasekhar, or “Chandra,” as he was known to colleagues, friends, and relatives, often asked his wife, Lalitha, to sing a song in which the composer laments the cycles of births and deaths that follow him through life. Beginning with an odd incident provoked by Arthur Eddington, Britain's preeminent astrophysicist in the 1910s and 1920s, cycles of intellectual births and deaths became the pattern of Chandra's creative life in science. Lalitha describes this unique approach in a remembrance: “Each field, or cycle . . . took from ten to fifteen years, for the selection of the subject for investigation, study of the available scientific literature on the subject, his own research that followed, the scientific papers he wrote on the subject, and, finally, the way he gathered all the material that lay in front of him into a coherent whole that was the book on the subject.”

When the book was completed, it was truly a death for Chandra: he had no more to say on the subject, refusing to spend time on the residue of minor issues remaining. “It was not in his spirit to pick up the crumbs,” writes Lalitha. A “fallow period” would follow while he searched for a new field. It could be a frustrating and depressing time for him, and he would say to Lalitha, “Your friend [the composer], sing his song.”

The exigencies of his life and career forced Chandra into several drastic cultural changes, each of which must have also seemed to him like a death and difficult birth. He was a native of southern India, and he said throughout his life that he felt at home only in India. Nevertheless, he left India at age nineteen and never returned except for visits. India could not offer him the graduate training he needed in astrophysics, and later afforded no suitable career opportunities for him. He went to Trinity College, Cambridge, for his graduate degree and a subsequent appointment as a Trinity fellow. The cold English climate, the bland English food, and the occasional eccentricities of the English were major and minor obstacles, but Chandra made many lasting friendships in England and would have stayed if there had been suitable job prospects. He was advised that there were none, so he moved on to a third culture, in America. First it was Harvard, then the Yerkes Observatory, and finally Chicago, where he and Lalitha remained. In America, Chandra built his unparalleled reputation as a theorist, mathematician, teacher, research adviser, editor, science historian, and storyteller.

Chandra saw himself as a man on a ladder, and kept a reminder of the metaphor on the wall of his office in a photograph taken by the artist Piero Borello. The picture shows a man who has half ascended a ladder leaning against a bright, almost featureless, but beautifully contoured wall. The man and the ladder, echoed by their shadows, seem strangely unequal to the task of ascending the wall. Chandra earned a copy of the photograph by explaining to the artist what the picture meant to him: “What impressed me about your picture was the extremely striking manner in which you visually portray one's inner feeling toward one's efforts at accomplishments; one is half way up the ladder, but the few glimmerings of structure which one sees and to which one aspires are totally inaccessible, even if one were to climb to the top of the ladder. The realization of the absolute impossibility of achieving one's goals is only enhanced by the shadow giving one an even lowlier feeling of one's position.”

These bleak words, quoted by Chandra's biographer Kameshwar Wali, provide no clue to Chandra's motivation. He simply was, in the most profound sense of the word, a scholar, “an ideal scholar of physics,” Victor Weisskopf told Wali, “nothing of pushiness, nothing of job seeking, publicity seeking, or even recognition seeking. . . . His deep education, his humanistic approach . . . , his knowledge of world literature, and in particular English literature, are outstanding. I mean you’d hardly find [another] physicist or astronomer who is so deeply civilized.” As a scholar, Chandra was “forever learning,” remarked one of his students. “Chandra couldn't care one bit about the establishment. Everything he did was out of being curious in a productive way.”

The scholar's challenge, as Chandra put it in his Nobel lecture, “is a quest after perspectives” in each chosen field. He meant by that simply “a view of my own.” His urge was “to present my point of view ab initio, in a coherent account with order, form, and structure.” He did so, repeatedly, over a period of about six decades.

Astrophysics involves the very big, the very small (in attempts to trace the history of the universe to its atomlike origins), and the very complex. Chandra had a grasp of the complexities of astrophysics that was unequaled by any of his contemporaries. In one of his cycles of study on a topic, he could assimilate the fundamentals in a field, assess their importance, build his own perspective, and express it in a comprehensive monograph. None of Chandra's colleagues in astrophysics, or in the broader physics community, could do so much.

Miracles Not Welcome

Chandra was a mathematical physicist, perhaps more so than any of the other physicists in these chapters, with the exception of Newton. All physicists use mathematics, but few qualify as both mathematicians and physicists, as Chandra (and Newton) did. Even Einstein, whose creative use of the mathematics of differentia geometry in arriving at his gravitational field equations was supreme, lacked the mathematical skill to find some of the important solutions to the equations. Chandra was sure that Newton would have done better.

For Chandra, mathematics was nature's language. “He talked to these equations personally and intimately till they gave up their secrets to him,” as one colleague puts it. Unlike many other great physicists, Chandra had more faith in the mathematical message than in his physical intuition. And if at all possible, the mathematical account had to be clear, complete, and exact. No approximations (except as a last resort). No magic. “Miracles were not welcome, only clarity and perfection,” his friend Rafael Sorkin says in a reminiscence. As another colleague put it, “Rather than being interested in new laws of Nature, Chandra strove to produce exact (and in general analytical) solutions to specific problems.”

When Chandra started on a research problem, he could not let it go until he found the best solution. Sometimes, when progress was blocked, he needed inspiration from a sympathetic colleague. His favorite muse was the Oxford theorist Roger Penrose. “Whenever I meet a stumbling block,” he told a friend, “I go and meet Roger Penrose.” Chandra was in Chicago and Penrose in Oxford, so the meetings required transatlantic plane trips on Chandra's part, and the visits were short. “We spend an hour together in the morning when I present him with my problem. We have four or five hours of discussion after lunch,” Chandra said. “Then at dinner we talk of other things and I fly back.” These “lightning visits,” as Penrose called them, were always beneficial for Chandra: “In no case has he [Penrose] not cleared up my doubts in physics or mathematics. An amazing man.”

Chandra did not like to leave loose ends in his work before he moved on to a new field, but there was one he could not avoid. Thanks to Eddington's opposition and Chandra's failure to muster the kind of support he needed in the physics community, Chandra had to turn his back on an intriguing question raised by his theory of white dwarfs: if a star is too massive to end its days as a white dwarf, what is its fate?

One answer was provided in 1939 by Robert Oppenheimer and his student George Volkoff, with some assistance from the Caltech theorist Richard Tolman. They composed a mathematical theory of “neutron stars,” stellar objects resembling white dwarfs except that gravitational collapse is balanced by a neutron pressure instead of an electron pressure. Whereas white dwarfs are roughly the size of Earth, neutron stars are even smaller and denser, with diameters of less than a few hundred kilometers. Oppenheimer and Volkoff patterned their calculation after Chandra's, with the difference that they were forced to use Einstein's theory of gravitation rather than Newton's, as Chandra had been able to do. Like Chandra's conclusion for white dwarfs, they found that there is a mass limit beyond which a dying star cannot form either a white dwarf or a neutron star.

What then? Another Oppenheimer paper in 1939, this one written with his student Hartland Snyder, implied, although it did not state explicitly except in the mathematics, the possibility that a massive star could collapse gravitationally all the way to an object of incredible density that swallows everything in it vicinity, including light. At first these voracious stellar objects were too bizarre for most astrophysicists to contemplate, but by the 1950s two intrepid theorists, John Wheeler and Yakov Zel'dovich, were picking up the research trail left by Chandra and Oppenheimer. One of Wheeler's contributions was an intriguing name, “black holes,” for regions of spacetime in this state of extreme gravitational collapse.

During the 1960s, Chandra's cycle of study, research, and writing concerned general relativity and relativistic astrophysics. In the 1970s he turned to black hole research. When he did this work, it was late in his career; he was in his sixties. No doubt it gave him great satisfaction to come full circle, back to the theme that began his career as an astrophysicist. In 1983, Oxford University Press published his monumental book The Mathematical Theory of Black Holes. In that same year, the Swedish Academy finally caught up with history and awarded Chandra a Nobel Prize, at least partly for his white dwarf research, done fifty years earlier. This must have been a record for the time elapsed between the work done and the awarding of the prize.

For his final study, Chandra chose a remarkable subject—Isaac Newton. Chandra was a student of science history and biography, and he had a wide acquaintance among his contemporaries in physics and astrophysics. But for him one scientist stood above all those of the past and present, and that was Newton. He decided to pay homage to Newton, and to try to fathom his genius, by translating “for the common reader” the parts of Newton's Principia that led to the formulation of the gravitation law.

Newton relied on geometrical arguments that are all but incomprehensible to a modern audience. To make them more accessible, Chandra restated Newton's proofs in the now conventional mathematical languages of algebra and calculus. His method was to construct first his own proof for a proposition and then to compare it with Newton's version. “The experience was a sobering one,” he writes. “Each time, I was left in sheer wonder at the elegance, the careful arrangement, the imperial style, the incredible originality, and above all the astonishing lightness of Newton's proofs, and each time I felt like a schoolboy admonished by his master.”

Chandra's complex personality had a dark side. I have mentioned his pessimistic fascination with the picture of the man on the ladder. He called himself a “lonely wanderer in the byways of science.” This dim outlook was the result of several influences: living apart from his native culture, his intense working habits (he regularly worked thirteen hours a day), and late in his life, the ordeal of a heart attack followed by bypass surgery. But the “lonely wanderer” found rewards. He continued on his solitary path because he knew there would be breathtaking vistas. In an essay titled “Pursuit of Science” he wrote:

The pursuit of science has often been compared to the scaling of mountains, high and not so high. But who amongst us can hope, even in imagination, to scale the Everest and reach its summit when the sky is blue and the air is still, and in the stillness of the air survey the entire Himalayan range in the dazzling white of the snow stretching to infinity? None of us can hope for a comparable vision of nature and the universe around us, but there is nothing mean or lowly in standing in the valley below and waiting for the sun to rise over Kanchenjunga.