Editing Subrahmanyan Chandrasekhar (section)

==Career and research==
[[File:Subrahmanyan Chandrasekhar harvard.jpg|thumb|Chandrasekhar in 1934]]
===Early career===
In 1935, Chandrasekhar was invited by the director of the Harvard Observatory, [[Harlow Shapley]], to be a visiting lecturer in theoretical astrophysics for a three-month period. He travelled to the United States in December. During his visit to Harvard, Chandrasekhar greatly impressed Shapley, but declined his offer of a Harvard research fellowship. At the same time, Chandrasekhar met [[Gerard Kuiper]], a noted Dutch astrophysical observationalist who was then a leading authority on white dwarfs. Kuiper had recently been recruited by [[Otto Struve]], the director of the [[Yerkes Observatory]] in [[Williams Bay, Wisconsin]], which was run by the [[University of Chicago]], and the university's president, [[Robert Maynard Hutchins]]. Having known of Chandrasekhar, Struve was then considering him for one of three faculty posts in astrophysics, along with Kuiper; the other opening had been filled by [[Bengt Stromgren]], a Danish theorist.<ref name="Chandra_bio_INSA"/> Following a recommendation from Kuiper, Struve invited Chandrasekhar to Yerkes in March 1936 and offered him the job. Though Chandrasekhar was keenly interested, he initially declined the offer and left for England; after Hutchins sent a radiogram to Chandrasekhar during the voyage, he finally accepted, returning to Yerkes as an assistant professor of Theoretical Astrophysics in December 1936.<ref name="Chandra_bio_INSA"/> Hutchins also intervened on an occasion where Chandra's participation on teaching a course organised by Struve, was vetoed by the dean [[Henry Gale (astrophysicist)|Henry Gale]] based on a racial prejudice; Hutchins said "By all means have Mr. Chandrasekhar teach".<ref>{{Cite book|url=https://www.nap.edu/read/5859/chapter/4|doi=10.17226/5859|title=Biographical Memoirs|year=1997|isbn=978-0-309-05788-2}}</ref>

Chandrasekhar remained at the University of Chicago for his entire career. He was promoted to associate professor in 1941 and to full professor two years later at the age of 33.<ref name="Chandra_bio_INSA"/> In 1946, when [[Princeton University]] offered Chandrasekhar a position vacated by [[Henry Norris Russell]] with a salary double that of Chicago's, Hutchins incremented his salary matching with that of Princeton's and persuaded Chandrasekhar to stay in Chicago. In 1952, he became the [[Morton D. Hull]] Distinguished Service Professor of Theoretical Astrophysics and [[Enrico Fermi Institute]], upon [[Enrico Fermi]]'s invitation. In 1953, he and his wife, Lalitha Chandrasekhar, took American citizenship.<ref>{{Cite news |url=http://www.financialexpress.com/lifestyle/science/s-chandrashekhar-indias-great-astrophysicist-why-google-doodle-is-celebrating-the-nobel-prize-winner/899544/ |title=S Chandrashekhar, India's great astrophysicist: Why Google Doodle is celebrating the Nobel prize winner |date=19 October 2017 |work=The Financial Express |access-date=2017-10-19 |language=en-US}}</ref>

After the Laboratory for Astrophysics and Space Research (LASR) was built by NASA in 1966 at the university, Chandrasekhar occupied one of the four corner offices on the second floor.  (The other corners housed [[John Alexander Simpson|John A. Simpson]], [[Peter Meyer (astrophysicist)|Peter Meyer]], and [[Eugene N. Parker]].) Chandrasekhar lived at 4800 Lake Shore Drive after the high-rise apartment complex was built in the late 1960s, and later at 5550 Dorchester Building.

=== Dispute with Eddington ===
{{Main|Chandrasekhar–Eddington dispute}}
After graduating from Cambridge, Chandrasekhar, who was in close contact with Arthur Eddington, presented a full solution to his stellar equation at the [[Royal Astronomical Society]] meeting in 1935. Eddington booked a talk right after Chandrasekhar, where he openly criticized Chandrasekhar's theory. This depressed Chandrasekhar and sparked a scientific dispute. Eddington refused to accept a limit for the mass of a star and proposed an alternative model.<ref name=":0">{{Cite journal |last=Wali |first=Kameshwar C. |date=1982-10-01 |title=Chandrasekhar vs. Eddington—an unanticipated confrontation |journal=Physics Today |language=en |volume=35 |issue=10 |pages=33–40 |doi=10.1063/1.2914790 |bibcode=1982PhT....35j..33W |issn=0031-9228|doi-access=free }}</ref>  

Chandrasekhar sought support from prominent physicists like [[Léon Rosenfeld]], [[Niels Bohr]] and [[Christian Møller]] who found Eddington's arguments lacking. The tension persisted through 1930s, as Eddington continued to openly criticize Chandrasekhar during meetings and the two compared each other's theories in publications. Chandrasekhar ultimately completed his theory of white dwarfs in 1939, receiving praise from others in the field. Eddington died in 1944, and despite their disagreements, Chandrasekhar continued to state that he admired Eddington and considered him a friend.<ref name=":0" />

===World War II===

During World War II, Chandrasekhar worked at the [[Ballistic Research Laboratory]] at the [[Aberdeen Proving Ground]] in Maryland.  While there, he worked on problems of [[ballistics]], resulting in reports such as 1943's ''[[:s:On the Decay of Plane Shock Waves|On the decay of plane shock waves]]'', ''[[:s:Optimum height for the bursting of a 105mm shell|Optimum height for the bursting of a 105mm shell]]'', ''[[:s:On the Conditions for the Existence of Three Shock Waves|On the Conditions for the Existence of Three Shock Waves]]'',<ref>{{cite report |last=Chandrasekhar |first=S. |year=1943 |title=On the conditions for the existence of three shock waves |publisher=Ballistic Research Laboratory, Aberdeen Proving Ground |id=367}}</ref> ''[[:s:On the Determination of the Velocity of a Projectile from the Beat Waves Produced by Interference with the Waves of Modified Frequency Reflected from the Projectile|On the Determination of the Velocity of a Projectile from the Beat Waves Produced by Interference with the Waves of Modified Frequency Reflected from the Projectile]]''<ref>{{cite report |last=Chandrasekhar |first=S. |year=1943 |title=On the Determination of the Velocity of a Projectile from the Beat Waves Produced by Interference with the Waves of Modified Frequency Reflected from the Projectile |publisher=Ballistic Research Laboratory, Aberdeen Proving Ground |id=365}}</ref> and ''[[:s:The normal reflection of a blast wave|The normal reflection of a blast wave]]''.<ref>{{cite report |last=Chandrasekhar |first=S. |year=1943 |title=Optimum Height for the Bursting of a 105mm Shell |id=BRL-MR-139 |publisher=Army Ballistic Research Lab Aberdeen Procing Ground MD |url=https://apps.dtic.mil/dtic/tr/fulltext/u2/492801.pdf|archive-url=https://web.archive.org/web/20191129131115/https://apps.dtic.mil/dtic/tr/fulltext/u2/492801.pdf|url-status=dead|archive-date=29 November 2019}}</ref><ref name=standrews>{{cite web|last=O'Connor|first=J. J.|title=Subrahmanyan Chandrasekhar|url=http://www-history.mcs.st-andrews.ac.uk/Biographies/Chandrasekhar.html|website=Biographies|publisher=School of Mathematics and Statistics University of St Andrews, Scotland|access-date=21 May 2012|author2=Robertson, E. F }}</ref> Chandrasekhar's expertise in hydrodynamics led [[Robert Oppenheimer]] to invite him to join the [[Manhattan Project]] at Los Alamos, but delays in the processing of his security clearance prevented him from contributing to the project. It has been rumoured that he visited the [[Calutron]] project.

===Philosophy of systematization===

He wrote that his scientific research was motivated by his desire to participate in the progress of different subjects in science to the best of his ability, and that the prime motive underlying his work was ''systematization''. "What a scientist tries to do essentially is to select a certain domain, a certain aspect, or a certain detail, and see if that takes its appropriate place in a general scheme which has form and coherence; and, if not, to seek further information which would help him to do that".<ref>''The Works of the Mind'', p.176, edited by Robert B. Heywood, University of Chicago Press, 1947.</ref>

Chandrasekhar developed a unique style of mastering several fields of physics and astrophysics; consequently, his working life can be divided into distinct periods. He would exhaustively study a specific area, publish several papers in it and then write a book summarizing the major concepts in the field. He would then move on to another field for the next decade and repeat the pattern. Thus he studied [[stellar structure]], including the theory of [[white dwarfs]], during the years 1929 to 1939, and subsequently focused on [[stellar dynamics]], theory of [[Brownian motion]] from 1939 to 1943. Next, he concentrated on the theory of [[radiative transfer]] and the quantum theory of the [[hydrogen anion|negative ion of hydrogen]] from 1943 to 1950. This was followed by sustained work on [[turbulence]] and hydrodynamic and hydromagnetic stability from 1950 to 1961. In the 1960s, he studied both the equilibrium and the stability of ellipsoidal figures of equilibrium, and general relativity. During the period, 1971 to 1983 he studied the mathematical theory of [[black holes]], and, finally, during the late 80s, he worked on the theory of colliding [[gravitational waves]].<ref name = standrews/>

===Work with students===

Chandra worked closely with his students and expressed pride in the fact that over a 50-year period (from roughly 1930 to 1980), the average age of his co-author collaborators had remained the same, at around 30. He insisted that students address him as "Prof. Chandrasekhar" until they received their PhD degree, after which time they (as other colleagues) were encouraged to address him as "Chandra". When Chandrasekhar was working at the Yerkes Observatory in 1940s, he would drive {{convert|150|mi|km}} to and from every weekend to teach a course at the University of Chicago. Two of the students who took the course, [[Tsung-Dao Lee]] and [[Chen-Ning Yang]], won the Nobel prize before he could get one for himself. Regarding classroom interactions during his lectures, noted astrophysicist [[Carl Sagan]] stated from firsthand experience that "frivolous questions" from unprepared students were "dealt with in the manner of a summary execution", while questions of merit "were given serious attention and response".<ref name="C.)-1991">{{Cite book|title=Chandra : a biography of S. Chandrasekhar| last=Wali | first=Kameshwar C. |date=1991|publisher=University of Chicago Press|isbn=978-0226870540|location=Chicago|pages=[https://archive.org/details/chandrabiography0000wali/page/9 9]|oclc=21297960|url=https://archive.org/details/chandrabiography0000wali/page/9}}</ref>

===Other activities===

From 1952 to 1971 Chandrasekhar was editor of ''[[The Astrophysical Journal]]''.<ref>{{Cite journal | author=Helmut A. Abt | date=1 December 1995 | title= Obituary – Chandrasekhar, Subrahmanyan | journal=Astrophysical Journal | volume=454 | pages=551 | bibcode=1995ApJ...454..551A|doi = 10.1086/176507 | issn = 0004-637X}}</ref> When [[Eugene Parker]] submitted a paper on his discovery of [[solar wind]] in 1957, two eminent reviewers rejected the paper. However, since Chandra as an editor could not find any mathematical flaws in Parker's work, he went ahead and published the paper in 1958.<ref>{{cite journal |last1=Parker |first1=E. N. |title=Dynamics of the Interplanetary Gas and Magnetic Fields. |journal=The Astrophysical Journal |date=1 November 1958 |volume=128 |pages=664 |doi=10.1086/146579 |bibcode=1958ApJ...128..664P |url=https://adsabs.harvard.edu/pdf/1958apj...128..664p |access-date= |issn=0004-637X}}</ref>

During the years 1990 to 1995, Chandrasekhar worked on a project devoted to explaining the detailed geometric arguments in Sir [[Isaac Newton]]'s ''[[Philosophiae Naturalis Principia Mathematica]]'' using the language and methods of ordinary calculus.  The effort resulted in the book ''Newton's Principia for the Common Reader'', published in 1995.

Chandrasekhar also worked on collision of gravitational waves,<ref>{{cite journal|last1=Chandrasekhar|first1=S.|last2=Xanthopoulos|first2=B. C.|year=1985|title=Some exact solutions of gravitational waves coupled with fluid motions|journal=Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences|volume=402|issue=1823|pages=205–224|doi=10.1098/rspa.1985.0115|bibcode=1985RSPSA.402..205C |s2cid=120942390 }}</ref> and algebraically special perturbations.<ref>{{cite journal|last=Chandrasekhar|first=S.|year=1984|title=On algebraically special perturbations of black holes|journal=Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences|volume=392|issue=1802|pages=1–13|doi=10.1098/rspa.1984.0021|bibcode=1984RSPSA.392....1C |s2cid=122585164 }}</ref>