# Marcus du Sautoy at the Ilkley Literature Festival

My Saturday afternoon involved sitting in a hall in Ilkley watching children play musical chairs to demonstrate the population dynamics of lemmings. It’s not often that one can write that. As you can probably tell by the picture, I was at Marcus du Sautoy’s talk at the 2010 Ilkley Literature Festival.

The King’s Hall is one of Ilkley’s larger venues for the festival. Outside hangs a large banner for the Complementary Medicine Festival and an advert for a gig by Dr Feelgood (that’s rather fitting said my good friend Paul when we were in Ilkley last week for a different talk). However, Saturday was a mini Maths Day in Ilkley with Rob Eastaway giving two distinct talks at the Playhouse and Marcus du Sautoy giving his at the King’s Hall.

The talk, titled The Num8er My5teries, was billed for ages 0-100 and there was indeed a wide spread of ages filling the hall to capacity (about 500). Young people were well represented. The local science communicator Marty Jopson did the introductions — and sneaked in a plug for the Otley Science Festival (16-20 November in case you are interested).

The first half of the talk was about primes. Marcus began with a discussion of why David Beckham chose the prime number 23 as his shirt number when he joined Real Madrid. (I’m sure that there’s a good mathematical joke about Complex Madrid but I still haven’t come up with one yet. If you can think of one, email me.) Marcus was aptly dressed in a purple football T-shirt with an equation on the front and with Galilei and a 17 on the back. I’d never seen him give a talk like this before and the first thing I noted is that he talks faster in the flesh, but then he had a lot to get through. He moved on to different types of numbers such as triangular numbers, Fibonacci numbers and circle division numbers. The last set of numbers is not so well-known, their sequence begins 1,2,4,8,16. As I use them in my own school talks maybe I shouldn’t give away that the next one is *not* 32. This half of the talk even included a simulation of a national lottery game.

The second half was chaos. Well, not literally. It was about chaos. We were taken through Poincaré’s attempt on the three body problem and double and triple pendulums. We then moved on to the population dynamics of lemmings. This was brought to life by using children from the audience to play a game of musical chairs. Each game represented a year and those failing to find a seat represented the lemmings that died. (I wished I’d conceived of this demonstration for one of my talks. It’s a memorable bit of audience participation that gets the message across.)

The finish was a return to the start: football. Marcus showed how Roberto Carlos’ impossible goal can be explained with chaos. The talk was humorous and well pitched for a general audience. It didn’t involve any complicated equations – the most complicated in the hour-long talk was the equation on his shirt representing the path of a ball.

Judging by the comments of those near me the talk was well received. I overheard a couple of the ushers saying how enjoyable it was (and if you can communicate maths to those who didn’t actively want to be there, then you are doing something right.)

After the talk Marcus signed copies of his book, also called the Num8er My5steries. (Well, this is a literature festival so book-signing is a legally required part of the proceedings). The book proved popular, all copies provided by the local bookshop for signing were sold. Marcus kindly posed for a picture as you can see above and signed my copy of Finding Moonshine, one of his earlier books. Inspired by the front and back covers, see below, I asked him to sign it twice. Once in the front and once backward in the back.

Unfortunately, he wasn’t able to do the latter (lack of practice apparently) so I had to settle for a 180 rotation written at the back. So not only do I have a signed book, it is uniquely signed. Of course if he sees it for sale on eBay he’ll know it was me…