Subrahmanyan Chandrasekhar

Subrahmanyan Chandrasekhar (October 19th 1910 - August 21st 1995) is a astrophysicist and a Indian mathematician , born with Lahore, in the province of the Punjab, in the the Indies British (now Pakistan) and died in Chicago.

Biography

Chandrasekhar, more known under the name of “Chandra”, makes its studies with the Presidency College of Madras (now called Chennai). It carries out its doctorate under the direction of Ralph H. Fowler with Trinity College of the Université of Cambridge to the the United Kingdom and in 1933 at the 22 years finishes it age. Its work relates to the stellar evolution. It becomes (and remains) known to have determined beyond which limit a white Naine becomes unstable under certain conditions and crumbles in neutron star, initiating the process of Supernova. This limit, from now on known under the name of Limit of Chandrasekhar, is worth to him at the time a sharp controversy with the Astronome English Sir Arthur Eddington. He emigrates then with the the United States of America and obtains a station with the Université of Chicago of 1937 until his death in 1995, at the 84 years age. He obtains American nationality in 1953.

During its very scientific long career of more than one half-century and punctuated of more than 300 scientific articles, Chandrasekhar receives many distinctions. Subrahmanyan Chandrasekhar became member of the Royal Society the March 16th 1944. Its work on the Transfert of radiation is worth the to him Prix Rumford in 1957. He is also prize winner of the Médaille Bruce in 1952, the Gold medal of Royal Astronomical Society in 1953, the National Medal off Science (highest academic distinction in the United States) in 1966, the Médaille Henry Draper in 1971 and the Médaille Copley in 1984. The crowning of its career occurs in 1983, year when it jointly obtains the Nobel Prize of Physics with William Fowler “for her theoretical studies of the physical processes governing the structure and the evolution of the star S”. The Indian government also honoured it by allotting to him the Médaille Padma Vibhushan.

The Astéroïde (1958) Chandra was baptized in its honor. In 1999, NASA lance a contest to baptize its Space telescope X-rays (in the past called AXAF), put into orbit by the Space shuttle Columbia the July 23rd 1999. After more than 6000 proposals for names received of more than 50 countries, it is Chandra which was retained in the honor of Chandrasekhar.

Chandrasekhar was the nephew of the Nobel Prize of physics Chandrasekhara Venkata Raman, prize winner in 1930 for the discovery of the Raman Diffusion.

Work

Maximum mass of dwarf white and the controversy with Eddington

Chandrasekhar is regarded as the first scientist to have applied the laws of the restricted Relativité to astrophysics and in particular to the study of the internal structure of stars, work which he undertakes at the time of the voyage in boat that he carries out in 1930 to join England and to start his thesis. Chandrasekhar at the time of crossing the large scientists of his time, in particular Dirac, Eddington, Jean, Milne and Plaskett.

The principal conclusion of its work is that the dwarf white cannot exceed a certain mass: beyond this mass, the Pression of degeneration of the electrons cannot counter the effect of gravity. Commenting on the conclusion of its work, Chandrasekhar affirms in connection with what can become dwarf white whose mass exceeds the limit that it has just calculated that “One can only speculate in the other possibilities” ( One is left speculating one other possibilities. ). Such a conclusion unfortunately causes a refusal on behalf of the largest English astrophysicist of the time, Arthur Eddington, with the approval of which Chandrasekhar subjects its work. Eddington comments on them by concise “I think that it must exist a natural law which prevents a star from behaving way also absurd” ( I think there should Be has off law natural to prevent has star from behaving in this absurd way ). This famous sentence is marked the January 11th 1935 at the time of a conference to the Royal Astronomical Society, to which Chandrasekhar came to communicate its results. The president of Royal Astronomy Society then asks Eddington to speak on the same subject (without that being envisaged at the beginning). Eddington, while recognizing exactitude of work of Chandrasekhar, rejects them while asserting that dwarf white exceeding the mass limits would have of another choice to only become what it then described as being a Black hole (without using this term which dates from the years 1960), assumption that it judges too absurd for be reasonable. (Incidentally, neither Eddington nor Chandrasekhar mention the possibility that dwarf white is not transformed into neutron star like it had proposed Walter Baade and Fritz Zwicky a few months more early.)

It was often known as that Chandrasekhar had been very affected by this controversy with Eddington and it is this thesis which its biographer Kameshwar Wali presents, suggesting even that this final judgment by one of the celebrities of its time carried a long time shade in Chandrasekhar, so much so that it will play a part in the decision of Chandrasekhar to emigrate towards the United States to be able to exert his talents. However Williams Mac Created, witness of the controversy and present at the time of the conference of 1935 moderates these remarks notably, estimating that its decision to emigrate in the United States was especially justified by the prospect to obtain a permanent station in research, and that the two men always remained in good terms and had regularly discussed besides the problem of the maximum mass of dwarf white the several times before. According to Mac Created, one can with imagining more that Chandrasekhar was surprised to see at which point its conclusions disturbed Eddington. The fact is in any case that Chandrasekhar devoted to Eddington a work with the particularly eulogistic title, Eddington, the most distinguished astrophysicist off his time , ( litt. “Eddington, the most eminent astrophysicist of his time”). Another testimony, of the Nobel Prize of physics of James Cronin (which knew Chandrasekhar the ten last years of its life), however seems to indicate that on the contrary Chandrasekhar would have shown on the end of its life a certain form of rancour towards Eddington.

Other work

At the end of the Thirties, Chandrasekhar ceases being interested in the internal structure of stars. It then decides to change subject, not without to have published a reference book on the subject ( Introduction to the Study off Stellar Structure , in 1939). It is in fact this way of proceeding that it will adopt during all its career: it will be invested a few years in a given subject, publishing many scientific articles (more than 6 per annum on average during more than 50 years), and concluding the whole by a monograph from quality. It will publish some nearly ten: in addition to that already mentioned, most outstanding will be its work on the stellar evolution ( Principles off stellar dynamics , 1943), the radiative transfer ( Radiative transfer, 1950), the hydrodynamics ( Hydrodynamic and hydromagnetic stability , 1961), the configurations of balance of the ellipsoids ( Ellipsoidal figures off equilibrium 1968), and the hole blacks ( The mathematical theory off black holes , 1983). Of all this work, only the first will be mentioned by the Nobel Committee to justify the attribution of its price. It seems that Chandrasekhar somewhat suffered to see that it was not the whole of its work which was rewarded. It is in any case allowed to evoke its other work in the speech which it makes during the handing-over of its Nobel Prize.

The last subject in which Chandrasekhar is interested is that of the black holes. Its major contribution rests on the mathematical study of the Perturbation S around the solutions of the black hole type of the equations of Einstein, in particular that of the Mathématicien New Zealand Roy Kerr. Chandrasekhar will be allured by the beauty of this solution about which he will speak in extremely eulogistic terms (see the article on Roy Kerr). Its work on the subject will be published in an impressive monograph which undoubtedly illustrates best its capacities except par, The mathematical theory off black holes .

Chandrasekhar was also editor association of the review Astrophysical Journal of 1952 with 1971 period during which it contributed largely to the rise of this newspaper which is now among the best scientific newspapers dealing with astrophysics. During its career it supervised the theses of 51 students of the University of Chicago.

See too

External bonds

  • Speech made during the handing-over of the Nobel Prize of physics

  • Contest launched for the name of satellite AXAF
  • Chandrasekhar by NASA
  • Biography of Chandrasekhar
  • Chandrasekhar on the site of the Foundation Nobel
  • US India-born astrophysicist - Chandra observatory: tribute to has legend by Rajesh Kochhar, article published in The Tribune , Indian newspaper, on July 27th, 1999
  • Nécrologie, not William H. Mac Crea and Comment of James Cronin
  • Nécrologie, by R.H. Garstang
  • Nécrologie, by Lynden-Beautiful Donald
  • Autobiographie of Chandrasekhar, on the site of the Foundation Nobel

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