At the time of writing The Man Who Knew Infinity is available to watch on
BBC iPlayer, or it can be bought or rented via
Amazon Prime Video.
The Man Who Knew Infinity is a biographical drama about reallife Indian
Mathematician Srinivasa Ramanujan, who made a number of contributions to pure
mathematics during his relatively short life. The movie focuses on his work
with English Mathematician G. H. Hardy at Cambridge University following a
postal correspondence that convinced Hardy of Ramanujan's brilliance.
Born in 1887 into a poor, deeply religious family in what is now Tamil Nadu
(then Madras), India, Ramanujan had almost no training in formal mathematics
yet showed astonishing ability and interest in the subject from an early age.
He suffered from various health problems throughout his life and, in common with a number of other notable mathematicians, died at a relatively early age  a fact which I don't consider to be a major spoiler.
The movie stars the always fantastic Dev Patel in the lead role, with Jeremy
Irons as Hardy. Together they compellingly portray what must have
been a complicated relationship given a historical backdrop that includes not
just British rule in India (and associated widespread attitudes that seem
abhorrent today), but also the outbreak of the First World War, all under a thick frost of academic elitism.
Early on, I noticed the
"you know this guy's good at maths because he did some quick maths in his
head"
trope making an appearance, but fortunately such clunky exposition is rare:
the only other example that springs to mind is the famous "taxicab number" anecdote
that appears out of place in a way which feels like it had been forgotten and
then hurriedly slotted in almost at random. These did not spoil my enjoyment
of what felt like a largely sympathetic and genuine telling of Ramanujan's story.
The mathematical content is believable without rendering the experience inaccessible to nonmathematicians: there's a fair amount of background chalkboard setdressing that isn't immediately irrelevant if you know what you're looking for; nor does it detract from events if you don't. The occasional scripted reminder that we're watching mathematicians at work manages to straddle the line between pseudomathematical gibberish and needlessly complicated textbook quotes quite well, with what little mathematical knowledge is required to follow the plot explained with a slight but forgivable grinding of gears.
In terms of its suitability for budding mathematicians, this an introduction to some real personalities who have contributed to the field of mathematics in relatively recent (i.e., not ancient) history  and not just Ramanujan and Hardy: there's a definite "spot the famous mathematician in the background cast" drinking game to be devised  not to mention a welcome break from the usual retelling of contemporary stories in mathematics which is often not very diverse at all. There's also a thread with genuine mathematical importance running through it: this is Hardy's dogged insistence that Ramanujan's results are not enough; that his seemingly magical plucking of answers and formulae from the air (or, as he romantically claims, finding them placed on his tongue in his sleep by his god) and committing them to paper neither constitutes true mathematical accomplishment nor demonstrates its intrinsic beauty, both of which are only achieved with rigour such that only a true, undeniable and eternal mathematical proof can provide. Hardy's initial frustration as he clashes with Ramanujan on this point will be familiar with any modern teacher of mathematics.

The Man Who Knew Infinity: A Life of the Genius Ramanujan (Book): amzn.to/3q8m65v 
I have no idea how "true" the story is, but I will take the opportunity to state that I don't
believe that a movie such as this has any responsibility to
be completely accurate: the role of a biographical or historical drama (in my opinion) is not
to provide me with a succession of facts and figures, but to interest me
enough in the story that I want to find out the truth behind the stories. In this,
for me, it succeeded.
This 2015 British movie is based on a book published in 1991, The Man Who Knew Infinity: A Life of the Genius Ramanujan, by American biographer and science writer Robert Kanigel and, now I've seen the movie I fully intend to seek out a copy of the book. I would like to hope that others who watch The Man Who Knew Infinity might feel similarly and want to delve a little deeper, whether that might be into the story of Ramanujan's life, specific aspects of his and/or Hardy's work, the historical backdrop, or some of the other personalities that we meet throughout its 108 minute running time: if so, it has done its job.
I would recommend The Man Who Knew Infinity to anybody looking for some gentle, interesting viewing rooted in the real world, regardless of their feelings towards mathematics, but especially if they are looking to expand their understanding and knowledge of key figures in its relatively contemporary history.
Have you seen The Man Who Knew Infinity? Please post your own thoughts (or a link to your own review) in the comments!
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