Nephew of the Indian physicist Chandrasekhara Venkata Raman, the Lahore-born, Presidency College-educated Chandra first worked out the Chandrasekhar limit during a voyage to Cambridge in 1930, although he had begun this work while still in Madras.
While every high schooler today learns about white dwarfs and black holes, it was then thought that white dwarfs would be the end-of-life for all stars. Realising that Einstein’s relativistic effects would become important at the core of white dwarfs, Chandra sought to mathematically theorise the same. His calculations predicted the physically impossible to measure negative radii of white dwarfs, which had evolved from stars over a certain critical mass; thus effectively concluding that such stars could not turn into white dwarfs. Yet the core of this work, known as the Chandrasekhar limit, was ignored for decades even as Chandra went on to make remarkable contributions in several other fields.
As a young doctoral student at Cambridge, Chandra sent this work to his advisor Ralph Fowler, who sent it on to the astrophysicist Edward Arthur Milne for expert advice. The recommendation of these men as members was crucial to publish Chandra’s paper in the Monthly Notices of the Royal Astronomical Society. While offering much encouragement and advice, both were uninterested in sending the paper ahead for publication.
In his excellent biography of Chandrasekhar, the physicist Kameshwar Wali noted that the astrophysicist interpreted Chandrasekhar’s results as contradicting his own idea, that every star had a degenerate core. Perhaps foreshadowing his eventual move to the US in 1936, where he would spend the rest of his career, Chandra eventually sent the paper to the US-based Astrophysical Journal where it was published in 1931.
In subsequent works, Chandra responded to some of Milne’s criticisms. Cautious about English journals, he sent this paper to the German Zeitsschrift fur Astrophysik and as fate would have it, Milne was asked to referee. The paper was finally published in the journal in 1932 with Chandra’s now oft-quoted words:
“For all stars with a mass greater than M, the matter does not become degenerate. Great progress in the analysis of stellar structure is not possible unless we can answer the following fundamental question: what happens if we go on compressing the matter indefinitely?”
As Wali notes, had the astrophysics community made a serious attempt to address Chandra’s question, neutron stars and black holes might have been quickly theorised. But given others’ lack of interest and encouragement, Chandra moved on to other problems during his doctoral studies, returning to the question only in 1934. He was invited to present his results at a meeting of the Royal Astronomical Society in 1935 where he would encounter the betrayal and humiliation that would shape his scientific career.
The legendary astrophysicist Sir Arthur Eddington who (among other things) had been central to the acceptance of Einstein’s ideas took a keen interest in Chandra’s developing work, often even visiting the young scholar in his rooms. Chandra was unsurprised as it was likely that his conclusions would prove that not all stars could have degenerate cores surrounded by ordinary matter – thus conclusively proving Eddington right in an key controversy between the latter and Milne. He was thus surprised to see Eddington mentioned as the author of a paper with a title identical to his own in the programme of the RAS’ meeting, but gave it little thought.
Delivering his paper right after Chandra’s, Eddington claimed that there was no such thing as Chandra’s relativistic degeneracy; arguing that “there should be a law of nature to prevent a star from behaving in this absurd way.” Arguing that Chandra’s formula combined relativity mechanics with non-relativity quantum theory, Eddington did not “regard the offspring of such a union as born in lawful wedlock.” Before Chandra could respond, the next speaker was called.
In private communication over the next few months, many of the great minds of interwar physics including Rosenfeld, Bohr, Dirac and Pauli sided with Chandra, but were unwilling to publicly make an authoritative statement. At a talk in Harvard, Eddington termed Chandrasekhar’s notions a “stellar buffoonery”. He continued his attack at the Paris meeting of the International Astronomical Union in July 1939, where despite protocol, Chandra was not allowed to reply to this final confrontation. Eddington passed away in 1944.
In the face of such opposition, Chandra moved on to other fields. It would be a generation before the Chandrasekhar limit would be taken seriously by astrophysicists; experimental confirmation of sorts would come in 1972 with the discovery of the first black hole in the Cygnus constellation.
Chandra, his biographer and historians of science have long speculated about the reasons for Eddington’s strange behaviour as well as the behaviour of the wider scientific community. Eddington was likely motivated not just by the threat Chandra’s work represented to his own ideas, but also by his being unconvinced of the scientific merit in his theory.
Wali speculates that Eddington’s keen initial encouragement was motivated by the notion that in working out the full theory, Chandra would discover for himself that every star, no matter its mass could become a white star, thus demolishing the idea of a limiting mass. This still did not explain the virulence of the attacks, particularly from a man of Eddington’s stature to a young scholar. On multiple occasions, Chandra mentioned racism as a potential motivation – this notion is supported by recent work by the historian of science Arthur Miller, who also speculates that angst arising out of alleged suppressed homosexuality may have contributed to Eddington’s behaviour.
As for the scientific community, amongst astrophysicists, there was obvious unease at rocking the status quo by siding with a young unknown in a battle with an intellectual giant. The private support Chandra received was in large part from the larger community of physicists, who were more comfortable with his mathematics.
Indeed while he received astrophysics awards in his career, the first citation to mention his work on stellar structure came with the Dannie Heineman Prize in Physics in 1974. This recognition was finally sealed with the Nobel Prize in physics in 1983.
Astrophysics was however, on the fringes of the discipline that was physics. Wali notes that physicists saw astrophysics as clumsy, complicated and ambiguous and thus had little motivation to intervene in a “domestic matter among astronomers.”
Whatever the underlying reasons, the confrontation had a profound impact on the young scholar’s life. His exit from the conversation inaugurated a pattern to his research whereby he would enter a field, work for several years before publishing a monograph that became a classic, effectively initiating new questions for research before moving on to other fields. Thus his career had no less than seven periods during which he revolutionised several fields.
At a luncheon after the 1939 Paris meeting, Eddington apologised to Chandra, to which the latter responded by asking him if he had changed his mind. To Eddington’s terse no, Chandra responded “Then what are you apologising for?” and walked away.
Despite the horrific humiliation and sense of betrayal, Chandra soon regretted his reaction, and never lost his high personal regard for Eddington. Indeed his later lectures on Eddington were published with the subtitle: “The greatest astrophysicist of his time.”
The admiration seemed mutual, as the two even went on cycling trips and to Wimbledon together well after the fateful meeting. Eddington invited Chandra and his wife Lalitha home when they were married in 1936. According to Chandra, upon learning that the couple was leaving for America, he invited Chandra to his rooms and confided about the difficult circumstances he grew up in as well as about the loneliness of an intellectual life, prefacing the chat with: “Let’s not talk science.” Chandra added:
“Eddington was trying to add to our professional relationship a personal dimension. The enormous respect I felt for him made me feel grateful, grateful that I had such an opportunity to know him.”
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