Ramanujan's Living Legacy: From String Theory to AI
How a hundred-year-old genius continues to transform modern science
Discover how Ramanujan's work continues to impact modern physics (black holes, string theory), computing, and even artificial intelligence.
Ramanujan's Living Legacy: From String Theory to AI
Srinivasa Ramanujan died in Kumbakonam on 26 April 1920 at the age of thirty-two. He had been ill for years. He had written, in pencil, on whatever paper he could find, until almost the end. The last letter he sent to G.H. Hardy in Cambridge, dated 12 January 1920, contained a list of seventeen new functions which he called 'mock theta functions'. He gave examples, hinted at properties, and offered no proofs. He died fourteen weeks later. For the next eighty years, mathematicians had no idea what these functions actually were.
In 2002, a young Dutch mathematician named Sander Zwegers, working on his doctoral thesis at Utrecht, finally cracked the structure of the mock theta functions. They turned out to be the missing pieces of a deep theory connecting modular forms, harmonic Maass forms, and quantum field theory. Ten years later, in 2012, the string theorists Atish Dabholkar, Sameer Murthy, and Don Zagier showed that exactly these functions are the precise mathematical objects needed to count quantum states of certain black holes. A piece of mathematics scribbled by a dying man in a small town in Tamil Nadu had turned out to encode information about the interior of black holes. Ramanujan had been a hundred years ahead of physics.
This is not an isolated incident. It is the pattern of his entire posthumous life. Wherever modern mathematics or physics has gone deep into a hard problem, it has tended to find Ramanujan's notebooks waiting for it.
The Notebooks That Keep Producing
Ramanujan filled three large notebooks with results during his years in India before going to Cambridge. He left a fourth, written during his final illness, which was lost for half a century until George Andrews of Pennsylvania State University rediscovered it in a box at the Trinity College library in 1976. The four notebooks together contain roughly four thousand identities, formulas, and conjectures, almost none with proofs. The proofs of these results have been an active research project for more than a century. As of 2026, every major identity in the notebooks has been proved, but the deeper structures they belong to are still being uncovered. The notebooks are not a closed book of historical curiosities. They are an active research frontier.