The Fascinating History of the Chandrasekhar Limit

Young Chandra

Thanks to Phil Krause for suggesting this interesting subject – Deskarati –

When a star starts running out of fuel, it usually cools off and collapses into one of three compact forms, depending on its total mass, a White Dwarf a Neutron Star or a Black Hole. The Chandrasekhar limit is the maximum mass of a stable white dwarf star. It was named after Subrahmanyan Chandrasekhar, the Indian astrophysicist who predicted it in 1930 at the age of twenty.

After the earlier work of R.H Fowler and E.C. Stoner on the relationship between the density, energy and temperature of white dwarfs called the Fermi gas model a series of papers were published between 1931 and 1935 with there beginning starting on a trip from India to England in 1930, where the Indian physicist Subrahmanyan Chandrasekhar worked on the calculation of the statistics of a degenerate Fermi gas. In these papers, Chandrasekhar solved the hydrostatic equation together with the nonrelativistic Fermi gas equation of state, and also treated the case of a relativistic Fermi gas, giving rise to the value of the limit shown above.  But, Chandrasekhar’s work on the limit aroused great controversy.

This was mainly due to the opposition of the British astrophysicist Arthur Stanley Eddington. Eddington was aware that the existence of black holes was theoretically possible, and also realized that the existence of the limit made their formation possible. However, he was unwilling to accept that this could happen. After a talk by Chandrasekhar on the limit in 1935, he replied:

The star has to go on radiating and radiating and contracting and contracting until, I suppose, it gets down to a few km radius, when gravity becomes strong enough to hold in the radiation, and the star can at last find peace. … I think there should be a law of Nature to prevent a star from behaving in this absurd way!

Arthur Stanley Eddington

Eddington’s proposed solution to the perceived problem was to modify relativistic mechanics so as to make the law P=K1ρ5/3 universally applicable, even for large ρ. Although Bohr, Fowler, Pauli, and other physicists agreed with Chandrasekhar’s analysis, at the time, owing to Eddington’s status, they were unwilling to publicly support Chandrasekhar. Through the rest of his life, Eddington held to his position in his writings, including his work on his fundamental theory. The drama associated with this disagreement is one of the main themes of Empire of the Stars, Arthur I. Miller’s biography of Chandrasekhar. In Miller’s view:

Chandra’s discovery might well have transformed and accelerated developments in both physics and astrophysics in the 1930s. Instead, Eddington’s heavy-handed intervention lent weighty support to the conservative community astrophysicists, who steadfastly refused even to consider the idea that stars might collapse to nothing. As a result, Chandra’s work was almost forgotten.

Chandrasekhar’s infamous encounter with Arthur Eddington  led Chandra to consider employment outside of the U.K. (Later in life, Chandra on multiple occasions, expressed the view that Eddington’s behavior was in part racially motivated.)

Chandrasekhar won Nobel Prize for physics in 1983. 

Edited from Chandrasekhar limit

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One Response to The Fascinating History of the Chandrasekhar Limit

  1. Naan Glozi says:

    “He who has Art and Science also has religion
    But those who do not have them better have religion.”
    -Subrahmanyan Chandrasekhar (1910-1995)
    What a great quote for an Atheist. It also seems to suit Deskarati now they seem to be getting famous people that have met many of my heros making comments. Well done Deskarati, great site, keep it up!

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