## Articles

**Josefina Alvarez**describes the workings of the most famous search engine of them all. You'll need some linear algebra for this one, but it's worth the while!

**Lewis Dartnell**turns the universe into a matrix to model traffic, forest fires and sprawling cities.

**Charlotte Mulcare**uses milk to show how maths and stats can provide genetic answers.

*On the origin of species*, but also 200 years since the birth of its author, Charles Darwin. At the heart of Darwin's theory of evolution lies a beautifully simple mathematical object: the evolutionary tree. In this article we look at how maths is used to reconstruct and understand it.

*string theory*have nudged their way into public consciousness. It's a theory of everything in which everything's made of strings — or something like that. But why strings? What do they do? Where did the idea come from and why do we need such a theory?

**David Berman**has an equation-free introduction for beginners.

**Rob Eastaway**and

**John Haigh**find chance in church and work out the odds.

*any*tilings based on fiveness?

**Craig Kaplan**takes us through the five-fold tiling problem and uncovers some interesting designs in the process.