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Monday, September 12, 2016

The Indian physicist who ‘created’ a black hole Subrahmanyan Chandrasekhar

Cecile G. Tamura 
Subrahmanyan Chandrasekhar was known to the world as Chandra. The word chandra means "moon" or "luminous" in Sanskrit.
As a young doctoral student at Cambridge, Subramanian Chandrasekhar had deduced that certain types of stars, called white dwarfs, could not have a mass more than roughly 1.44 solar masses (the Chandrasekhar limit). If they exceeded this mass, they would undergo collapse under the pull of gravity. The collapse of a star exceeding the Chandrasekhar limit was a precursor to the idea of black holes.
When he presented his results in 1935 to the Royal Society, Britain’s most celebrated astronomer, Arthur Eddington (1882–1944) took violent objection on the grounds that Chandrasekhar had wrongly used quantum mechanics and that his proposed behavior for a star was simply absurd.
Physicists knew Eddington’s argument to be incorrect, but did not come out in Chandrasekhar’s defense—some thought it obvious, and some were afraid to contradict Eddington. Chandrasekhar left England (where all doors were closed to him in view of the above) and migrated to the USA to become one of the most influential and respected astrophysicists in the world.

His results came to be universally accepted and he won the Nobel Prize in 1983, over 50 years after his great discovery.…/the-indian-physicist-that-c…/…/lau…/1983/chandrasekhar-bio.html
Subrahmanyan Chandrasekhar, (born October 19, 1910, Lahore, India [now in Pakistan]—died August 21, 1995, Chicago, Illinois, U.S.) Indian-born American astrophysicist who, with William A. Fowler, won the 1983 Nobel Prize for Physics for key discoveries that led to the currently accepted theory on the later evolutionary stages of massive stars.

Chandrasekhar was the nephew of Sir Chandrasekhara Venkata Raman, who won the Nobel Prize for Physics in 1930.
Chandrasekhar was educated at Presidency College, at the University of Madras, and at Trinity College, Cambridge. From 1933 to 1936 he held a position at Trinity.
By the early 1930s, scientists had concluded that, after converting all of their hydrogen to helium, stars lose energy and contract under the influence of their own gravity. These stars, known as white dwarf stars, contract to about the size of Earth, and the electrons and nuclei of their constituent atoms are compressed to a state of extremely high density. Chandrasekhar determined what is known as the Chandrasekhar limit—that a star having a mass more than 1.44 times that of the Sun does not form a white dwarf but instead continues to collapse, blows off its gaseous envelope in a supernova explosion, and becomes a neutron star. An even more massive star continues to collapse and becomes a black hole. These calculations contributed to the eventual understanding of supernovas, neutron stars, and black holes.
Chandrasekhar joined the staff of the University of Chicago, rising from assistant professor of astrophysics (1938) to Morton D. Hull distinguished service professor of astrophysics (1952), and became a U.S. citizen in 1953. He did important work on energy transfer by radiation in stellar atmospheres and convection on the solar surface. He also attempted to develop the mathematical theory of black holes, describing his work in The Mathematical Theory of Black Holes (1983).
Chandrasekhar was awarded the Gold Medal of the Royal Astronomical Society in 1953, the Royal Medal of the Royal Society in 1962, and the Copley Medal of the Royal Society in 1984. His other books include An Introduction to the Study of Stellar Structure (1939), Principles of Stellar Dynamics (1942), Radiative Transfer (1950), Hydrodynamic and Hydromagnetic Stability (1961), Truth and Beauty: Aesthetics and Motivations in Science (1987), and Newton’s Principia for the Common Reader (1995).…/Subrahmanyan-Chandrasekhar