The Man Who Knew Infinity: A Life of The Genius Ramanujan

The Man Who Knew Infinity: A Life of The Genius Ramanujan is a fascinating biography of the early 20th-century Indian mathematician Srinivasa Ramanujan. It's both the story of his life and also the history of mathematics and scientific discoveries during the time period, spanning from the end of the 19th-century through World War I. What makes him different from many mathematicians in history is that he never received any formal training, and claimed that his insights were inspired by the family goddess he worshiped. Ramanujan was one of the most brilliant mathematicians to have ever lived and his story is just as fascinating as his discoveries.

The story starts off with Ramanujan's bringing up in Kumbakonam, a small town in the state of Tamil Nadu in southern India. A prominent center of both European and Indian education during the British Raj, it was known as the "Cambridge of south India". The book does delve into a lot of the history of Madras and Kumbakonam, but I won't do that for now. Ramanujan was deeply religious growing up and maintained it throughout his life, even after travelling abroad. He prayed to his family goddess Namagiri everyday, and claimed that all of his ingenious insights that he had into mathematics came were told to him in his dreams by Namagiri, which is doubted by many atheists and scholars till today. Ramanujan attends the government high school and excels in math but fails in everything else because his mind is so occupied all the time with numbers. He is later married to a local village girl named Janaki and takes up a job as a clerk at a local office, because he failed all of his subjects besides math and got his scholarship revoked. Ramanujan continues to do mathematics and is one day told by his head to write to professors abroad with his work. He writes to three and attaches some of his discoveries. Only one writes back - the Cambridge mathematician G.H. Hardy. The book tells the backstory of Hardy's life, which is just as fascinating as that of Ramanujan's. Hardy is astounded by the findings of this poor clerk in Madras with little training, and shows the results to his colleague and math prodigy, John Littlewood. Ramanujan is invited to Cambridge and takes classes on how to find and write mathematical proofs to finally publish his results, as Ramanujan never cared for proofs as everything just came to him. His time at Cambridge is however, far from merry, as the shadow of World War 1 falls over Cambridge, and Trinity College lawn is quickly turned into a makeshift hospital for soldiers who were wounded in fighting. Ramanujan also feels homesickness and out of place in English society. He can't eat anything in the Trinity dining halls due to being a strict vegetarian, and tensions between his wife and mother at home means that he barely gets to write to his wife during his stay there. Ramanujan also experiences racism as a subject of the British empire, and many of the English soldiers at Trinity treat him like his inferior. Ramanujan spends his day in his dark dorm room in damp and sullen England, away from the bustle of his village in southern India.
Tragedy strikes when Ramanujan comes down with tuberculosis and taken to a sanatorium. His drive for mathematics, however, does not stop. There's a famous story that when Hardy came to visit Ramanujan in the hospital, he was disappointed that his taxi cab's number was 1729 - it seemed rather dull to him and he hoped that it wasn't a bad omen. Ramanujan immediately said that 1729 is the smallest number that can be expressed at the sum of two cubes in two different ways - 10^3 + 9^3 and 12^3 + 1^3. This was truly the mathematical genius he was, and numbers like these are known today as Hardy-Ramanujan numbers. Ramanujan eventually went back to India and died of tuberculosis there at the mere age of 32 in 1920. He was however honored, as a member of the Royal Society, which is the prestigious aacademy of sciences chartered by the UK.
Ramanujan left behind a legacy worth remembering. During his short life span, he did groundbreaking work in the field of number theory, working on elliptic functions, partitions, series, continued fractions, and many more things. He also kept his findings in notebooks, and there was a lot of buzz in the mathematical community in 1976 when another one of his notebooks was found in 1976. What's even more amazing about what he achieved in his short life was that he had no formal training in mathematics, and simply came up with all of his discoveries on his own. People wonder if he would have been lost if Hardy had not "discovered" him, and there's also the question of how many amateur mathematicians are lost because of poverty and no connection to publish their works. If he had lived longer than 32, he could have achieved more wonders in math and truly would have achieved the recognition he deserved while he was living.
As for the book itself, Robert Kanigel is a fantastic writer and I did not find myself bored at any point in the book. He writes a captivating account of this genius's life, and provides plenty of background, both about the history of mathematics and the British rule in India and customs of Ramanujan's community, that I did not find myself confused at any point in the book. He does provide some mathematical proofs and mentions many of Ramanujan's findings, but they are not too complex and I think that almost all kids our age would be able to understand them by ease. There is also a movie based on this book that I have watched many times, but I would still recommend that you read the book, because it goes in so much more depth than the movie does. I would definitely recommend that you read this book - Ramanujan is a mathematician who truly deserves recognition for the work that he did but he is often not mentioned in mathematics textbook, so I think that this book is great to learn about the non-western history of mathematics. This not only serves as a book for people interested in mathematics and the history of science, but it's honestly for anyone who just wants to learn about the world and the history of innovation.