Subrahmanyan Chandrasekhar, born in Lahore (British India) and nineteen years old at the time, calculated in 1930, during his sea voyage from India to England — where he was to study at Cambridge on a scholarship from the Indian government — the maximum mass a white dwarf can have before collapsing under its own gravity. Applying relativistic quantum mechanics to the electron degeneracy pressure that holds white dwarfs up against gravitational collapse, Chandrasekhar shows that this limit is approximately 1.4 solar masses: above that value, no known quantum force can halt the collapse, and the star must turn into something else — what would later be identified as a neutron star or black hole. He presented his results in January 1935 before the Royal Astronomical Society in London. At that same meeting, Arthur Eddington — the unquestioned British authority on stellar astrophysics — publicly rejected the conclusion, calling it a 'reductio ad absurdum' of relativistic stellar behavior, without offering a concrete mathematical error in the calculation. Eddington's rejection, combined with his institutional authority, delayed general acceptance of the Chandrasekhar limit for years within the British astrophysical community. Chandrasekhar emigrated to the United States in 1937 and built the rest of his career at the University of Chicago. The limit that bears his name becomes one of the fundamental constants of stellar astrophysics: it explains the mechanism of Type Ia supernovae — used as 'standard candles' to measure cosmic distances — and establishes the theoretical threshold separating white dwarfs from the most extreme collapsed stellar objects.