Subrahmanyan Chandrasekhar (Public Domain Image)

by S. Prasad Ganti

The name Chandra brings two things to the minds of those who are inclined towards astrophysics and cosmology. One is the Chandrasekhar limit, which is equivalent to 1.4 times the mass of the Sun. Stars weighing more than the limit die a different death than those weighing less. Two is an X-ray space telescope named in his honor.

Subrahmanyan Chandrasekhar came from an illustrious family going back three generations, which was steeped in science and mathematics in British-colonized India. Chandra’s uncle was the great CV Raman who won the Nobel Prize in Physics in the early twentieth century for his “Raman Effect”. The family benefited from the English education system put together by the British Governor General Lord William Bentinck and Thomas Macaulay in the early 1800s. Though the British rule was widely criticized, a small minority of Indians benefited from this system, which was mainly created by the colonial power to turn out civil servants for the administration.

Chandra was very studious and precocious as a child. He took keen interest in mathematics and physics in his school and college days. Chandra published a paper that caught the attention of William Fowler of Cambridge University. Fowler helped Chandra to get a scholarship to study at Cambridge in the 1930s. On the voyage to England, Chandra came up with some ideas relating to what later became known as the “Chandrasekhar limit”. In those days, scientists knew that stars are born and eventually die, like all species do. They speculated that all stars end up as white dwarfs after they burn their fuel away. A white dwarf is a smoldering remains of a dead star. Chandra came up with the concept that not all stars end up the same way. Stars heavier than 1.4 times the weight of our own Sun end up as supernovae and eventually as neutron stars. Some really massive ones end up as black holes.

This concept was strongly opposed by Arthur Eddington who conducted a famous experiment in 1919 during a solar eclipse to prove Albert Einstein’s General theory of relativity. This opposition did not discourage Chandra but being a novice he could not stand up to Eddington. Paul Dirac and William Fowler were Chandra’s mentors at Cambridge where he got his PhD in 1933. Eddington and Fowler were his thesis examiners.

Chandra joined the University of Chicago as an Assistant Professor at its Yerkes Observatory in Williams Bay, Wisconsin. He remained in the US for rest of his life and became an American citizen. In Chicago, Chandra worked with the likes of Enrico Fermi and John Von Neumann. He got lot of praise from his colleagues and his students for his lasting contribution to the field of astrophysics. He became a Fellow of Royal Society of Britain in 1944. He was also the editor of Astrophysical Journal from 1955 to 1971 during which time the journal gained national stature.

Finally in 1983, history vindicated this great man. The idea for which Eddington reviled him, led to a Nobel Prize in physics, which he shared with his guru William Fowler. The Chandrasekhar limit like the Raman effect became part of physics vocabulary forever. More details on Chandra’s life and achievements can be found in the biography Chandra by Kameshwar Wali.