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

Source: gleech · Original review

One of the best biographies I've ever read. (The subtitle says it is about Ramanujan, but it is equally about Hardy, that perfect British intellect: more crystalline than Russell, more lofty than Moore, more self-critical than Hare, more fun than anyone, loveable atop it all.) Ramanujan's story is of course maximally moving to anyone with a shred of curiosity or pity. The most moving part of all is an absence, one of the darker thoughts among all thoughts:

How many Ramanujans, his life begs us to ask, dwell in India today, unknown and unrecognized? And how many in America and Britain, locked away in racial or economic ghettos, scarcely aware of worlds outside their own?

His research is patent throughout: he decodes South Indian religion and cuisine, British upper-class slang, and even something of the impressiveness of higher mathematics, while using mere natural language:

Ramanujan's work grants direct pleasure to only a few - a few hundred mathematicians and physicists around the world, perhaps a few thousand. The rest of us must either sit on the sidelines, and, on the authority of the cognoscenti, cheer - or else rely on vague, metaphoric, and necessarily imprecise glimpses of his work.

...mathematics is not best learned passively; you don’t sop it up like a romance novel. You’ve got to go out to it, aggressive, and alert, like a chess master pursuing checkmate.

Ramanujan himself left a tiny dense literature that we are still decoding:

Ramanujan's notebooks formed a distinctly idiosyncratic record. In them even widely standardized terms sometimes acquired new meaning. Thus, an "example" — normally, as in everyday usage, an illustration of a general principle — was for Ramanujan often a wholly new theorem. A "corollary" — a theorem flowing naturally from another theorem and so requiring no separate proof — was for him sometimes a generalization, which did require its own proof. As for his mathematical notation, it sometimes bore scant resemblance to anyone else's.

Many passages raise goosebumps: Kanigel unites the abstract and the bodily, the true and the human all-too-human.

You cannot say much about Ramanujan without resorting to the word self. He was self-willed, self-directed, self-made. Some might conceivably label him selfish for his preoccupation with doing the mathematics he loved without any great concern for the better of his family or his country...

Hardy discovered Ramanujan? Not at all: a glance at the facts of 1912 shows that Ramanujan discovered Hardy.

A life-giving book.