Subrahmanyan Chandrasekhar

Subrahmanyan Chandrasekhar spent 27 years working and living on the grounds of Yerkes Observatory in Williams Bay, Wisconsin. (UChicago Photographic Archive, apf1-01654, Hanna Holborn Gray Special Collections Research Center, University of Chicago Library)

It was written in the stars

Astrophysicist Subrahmanyan Chandrasekhar (1910–95) illuminated stellar evolution.

Subrahmanyan Chandrasekhar—child prodigy, predictor of black holes, Nobelist, and UChicago professor for nearly 60 years—often distilled his life into two sentences: “I left India and went to England in 1930. I returned to India in 1936 and married a girl who had been waiting for six years, came to Chicago, and lived happily thereafter.”

Chandrasekhar is best known for the earliest part of his career, when he determined the fate of massive stars and was betrayed by a mentor. Yet he spent the next six decades making equally influential breakthroughs in stellar structure and dynamics, and training a new generation of astrophysicists. He also faced discrimination and alienation, elided from the fairy-tale ending he liked to recount.

Chandra, as he was known, was born in 1910 in Lahore—then British India, now Pakistan—the third of 10 children. In Chandra: A Biography of S. Chandrasekhar (University of Chicago Press, 1990) his biographer Kameshwar C. Wali, a UChicago physicist in the late ’60s, describes him as a mischievous child with an early aptitude for math.

Chandra didn’t attend traditional school until he was 11; prior to that he was taught by tutors and allowed to follow his intellectual interests. Regarded as a mathematics prodigy, he entered Presidency College in Madras at 15, where he gravitated toward physics. His precociousness recalled that of his uncle C. V. Raman, who went on to win the 1930 Nobel Prize in Physics for demonstrating quantum effects in the scattering of light.

At 17 Chandra spent the summer working in his uncle’s lab, where early on he broke a crucial piece of equipment. Experimental physics was not in his future. But he befriended one of Raman’s colleagues, who introduced him to the work of Arnold Sommerfeld, one of several theorists transforming physics through quantum mechanics. This group included Ralph H. Fowler, who helped Chandra publish a paper in the Proceedings of the Royal Society of London, the first of about 400 articles—and numerous books—in his lifetime.

Near the end of his undergraduate studies, Chandra was offered a special Government of India scholarship to study in England. In 1930 he set out for the University of Cambridge. While at sea on one leg of the voyage, reading physics publications to pass the time, the 19-year-old Chandra famously arrived at his Nobel-winning insight.

Sixty-eight years earlier, astronomers had first observed a white dwarf: the small, hot, extremely dense remnant left after a star burns through its fuel. But it didn’t make sense—such an object shouldn’t be able to resist its own gravity and should have collapsed. Fowler, Chandra’s soon-to-be PhD adviser at Cambridge, solved the puzzle using quantum theory to explain the phenomenon.

Chandra’s maritime math took Fowler’s explanation a step further, calculating that the physics stabilizing ultra-dense white dwarfs worked only up to a point. Over a certain mass, a dying star in fact could not overcome gravity and would collapse into some incomprehensibly dense object (what we now call a neutron star) or maybe even an infinitely dense point (a black hole). That upper boundary, later named the Chandrasekhar limit, is about 1.4 times the mass of our sun.

His work built on Fowler’s research and that of Cambridge astronomer Arthur Eddington, who believed all stars were destined to become white dwarfs. As Chandra refined his calculations over four years in England, Eddington regularly dropped by to see how the work was progressing. When Chandra was ready to present his findings at the Royal Astronomical Society meeting in 1935, Eddington arranged for Chandra to have double the customary 15 minutes and scheduled his own presentation to immediately follow. When Chandra finished, Eddington ridiculed the young astrophysicist’s conclusion, publicly humiliating him.

In private, some colleagues reassured Chandra, but it would be more than 20 years before his limit was widely accepted. In one of his final interviews, he reflected on the incident: “Suppose Eddington, instead of finding that I was wrong, had instead said, ‘What you have done is very important.’ … Given Eddington’s reputation, he could have made me instantly a very well-known person.” But enjoying such early prominence, he said, could have diverted his research. “You lose your motivation to continue doing science.”

“The Eddington factor had the effect of closing the doors in England,” writes Eugene Parker, Chandra’s UChicago colleague and the discoverer of solar wind. (Parker wrote a biography for the National Academy of Sciences after Chandra’s death from heart failure in 1995.) His father suggested returning home, but Chandra “found himself increasingly out of sympathy with the political nature of academia in India.”

Chandra was invited to lecture for a few months at Harvard in early 1936. While he was there, the director of UChicago’s Yerkes Observatory, Otto Struve, PhD’23, offered him a position as research associate, with the promise of a tenure-track appointment at the University after a year. Harvard also offered a faculty position, but Struve was doing something new. He was recruiting “theoretical astrophysicists, a very rare breed in the United States” in those years, writes one of Chandra’s graduate students, Donald Osterbrock, PhB’48, SB’48, SM’49, PhD’52, in a brief history of Chandra’s time at Yerkes. Struve was merging theory and observational astronomy; he was also recruiting two of Chandra’s friends.

Against his father’s wishes, Chandra agreed to settle across the pond. But first he returned to India to see about a girl.

Chandra had been corresponding with his future wife for six years. They had been immediately drawn to one another, but their long-distance courtship was filled with uncertainty.

Chandra first met Lalitha in an honors physics course at Presidency College. Born Doraiswamy Lalithambal, she came from a family of educated women—uncommon in India at the time. Early marriage was out of the question for Lalitha and her female siblings and cousins. She would earn her master’s in physics first. In an autobiographical essay, she describes her love of physics as stemming from her interest in Marie Curie and the excitement in India over C. V. Raman’s Nobel Prize.

Lalitha had “noticed with interest the young man with a crew cut, always sitting behind her in the second row,” writes Wali. She asked him if she could see his laboratory record book, and he readily agreed. They shared the notebook from then on; at a party, Chandra gave her a rose. Days before he left for England, Chandra visited Lalitha’s home with books she’d requested; they sat in awkward silence until her family joined them.

At Cambridge he ventured an apprehensive letter: “Dear Miss Lalitha, I was for a long time hesitating whether I should allow myself the liberty of writing to you particularly as I am anxious not to displease you in any manner possible.” Encouraged by her swift reply, he wrote back without delay. Formalities turned to “sweet darling,” talk of physics turned to love, and soon they were engaged.

But in the spring of 1935, amid the dilemma of whether to move to America, Chandra told his father that he “realized that my relation with Lalitha was purely illusionary and that I really had not known her at all.” He had broken off the engagement.

A year later, before moving to Yerkes, Chandra visited India. He met with Lalitha to talk things over, and his decision to indefinitely postpone marriage “wilted away rather suddenly,” writes Wali. “She was more than a dream, she was quite real.”

They wed within a month—entering into a “love marriage,” unusual in their time—and soon moved to Williams Bay, Wisconsin, where Yerkes is located. Lalitha attended lectures at the observatory, and Chandra urged her to resume her physics research. “But I made the decision not to continue,” she told Wali, because she couldn’t devote all of her time. “Chandra had to give most of his time to his science. That is the way a scientist is made.”

Subrahmanyan and Lalitha Chandrasekhar
Subrahmanyan and Lalitha Chandrasekhar attend the 1939 dedication celebration of McDonald Observatory in the Davis Mountains of West Texas. (Photography by Elwood M. Payne; UChicago Photographic Archive, apf1-01661, Hanna Holborn Gray Special Collections Research Center, University of Chicago Library)

Chandra and Lalitha lived at Yerkes for 27 years. “If you were in Williams Bay,” said UChicago astrophysicist and Chandra’s graduate student Peter Vandervoort, AB’54, SB’55, SM’56, PhD’60, in a 2017 interview, “you might as well be at the South Pole. Small towns in southern Wisconsin are not exactly the natural homes of academicians.” But nearly all of UChicago’s astronomy department worked there and lived in University-owned houses on the observatory’s grounds.

When Chandra was recruited, Struve was restructuring the astronomy graduate program to include more physics. He increased the coursework at the observatory, and Chandra did the bulk of his teaching there. His lectures followed his research: stellar interiors and atmospheres, stellar dynamics, and molecular spectroscopy.

The lectures were “formal and highly mathematical,” writes Osterbrock—organized, logical, eloquent. “There was a kind of cadence, a rhythm and music, to his lectures,” said Vandervoort. At the same time, Chandra was known to have little patience: “Frivolous questions from people who did not appear to have studied the material thoroughly,” said Carl Sagan, AB’54, SB’55, SM’56, PhD’60, “were dealt with in the manner of a summary execution.”

Chandra taught astrophysics for 15 years, but in 1952, the astronomy department revised its curriculum—which he had largely designed—effectively removing him. For the second time in his career, Wali notes, Chandra felt humiliated. “Most astronomers did not have very much appreciation for theoretical work of the type that Chandra did,” said Vandervoort. He “had a sense of being largely rejected by the astronomical community.”

The disaffection between Chandra and his colleagues grew, and he reexamined his early residency at Yerkes from a new perspective. His fellow recruits had been appointed assistant professors immediately and promoted the following year with tenure. Yet Chandra had started as a research associate and been reappointed the next year as an assistant professor—with no salary increase—and remained thus for four years. The others had received funds and resources denied to him.

He had found it curious that his research associate offer came directly from Robert Maynard Hutchins. “Such an appointment,” said Chandra, “does not normally need the intervention of the president of the university.” Wali notes that in the early 1960s—long past his presidency—Hutchins gave a lecture about racial strife at UChicago that explained why. He described how the appointment of a leading theoretical astronomer had been opposed “because he was an Indian, and black.” (Hutchins often claimed the best thing he did for the University was appoint Chandra.)

The young astrophysicist had also been unaware that Henry Gale, AB 1896, PhD 1899, dean of the physical sciences, attempted to block him from lecturing on campus in 1938; once again, Hutchins intervened. Chandra and Lalitha had both faced racism in their personal lives, but he later admitted to naivete about its effects on his professional life. “I was not even aware that something impolite, something improper had been done to me,” he told Wali.

Shortly after the astronomy department “repudiated” Chandra, as Vandervoort described it, Enrico Fermi invited him to join the physics department. From that point on, Chandra taught physics almost exclusively. But he didn’t abandon astrophysics altogether; that same year he became managing editor of the Astrophysical Journal, and over the next 20 years almost single-handedly developed it into the field’s leading international publication.

During his career, Chandra advised at least 46 doctoral students and presided over 1,000 colloquia. He received 20 honorary degrees, was elected to 21 learned societies, and won several prominent awards, including the National Medal of Science and, in 1983, the Nobel Prize in Physics for the work he’d conducted 53 years before, as a young man at the very start of his journey.

When Chandra first proposed black holes, the idea was deemed absurd, UChicago astrophysicist Daniel Holz, SM’94, PhD’98, told the University podcast Big Brains. Even Albert Einstein—whose work seeded the idea of black holes—had doubts. But Chandra’s math was sound.

Over the decades, evidence of their existence emerged. In 2015 the Laser Interferometer Gravitational-Wave Observatory, of which Holz is a member, detected waves created by black holes colliding. Andrea Ghez, LAB’83, shared the 2020 Nobel Prize in Physics for discovering a supermassive black hole by studying the movement of nearby stars. And the Event Horizon Telescope has released two pictures of black holes—Chandra’s unimaginable abstraction now plain to see.