Posted on November 3, 2012
by Jack Kelly

Tags: readings

Now that I’m voyaging again, I have many more opportunities to read. Especially on this Port Davey trip, as the passengers are nowhere near as much work as the school students. I’ve previously mentioned my weakness for pop-mathematics books, but I don’t feel guilty reading a biography. The Man Who Loved Only Numbers is a biography of Paul Erdos, one of the most prolific and strangest mathematicians who ever lived.

Paul had a lot of trouble operating in the real world, and the book
is at its best when retelling these stories. He had little need for
money, travelled the world with a couple of suitcases, doing mathematics
all the way, loved grapefruits but couldn’t open them, had his own
language (children were called “epsilons”, a mathematician who retired
was “dead” but a mathematician who died had “left”) and didn’t see the
problem with ringing people at 5:00am, because that’s when they’d be
home. He one turned up at a colleague’s door one Christmas Eve, and the
first words out of his mouth were “Merry Christmas. Let *f(n)* be
the following function…”.

But even though his life was disconnected from the real world, he had plenty of time for the people who lived in it. He had a peculiar knack for matching mathematical problems to people, and mentored a great many mathematicians during his travels. Needing only a little money, he gave most of it to charities, beggars and the homeless. He loved all children, regardless of their mathematical talent, and cared for anyone he thought was vulnerable. He was also an extremely principled man: in 1954 he was invited to a conference in Amsterdam, but the US denied him a re-entry permit. He resigned his university position and left the country.

So here is an apparent contradiction: Erdos clearly lived apart from the real world, but cared deeply about his fellow mathematicians. I find his life hugely inspiring: he was able to wander the world, working on mathematics and mathematicians, getting along in his own peculiar way. The best part about his story is that his family and friends made this life possible. It would have been far too easy to write someone like him off as crazy.

The book loses a little steam towards the end: the section on Diophantine equations and Fermat’s last theorem feels like it’s included just because.