## Articles

*fractal*, introduced in the mid 1970's by Benoit Mandelbrot, is now commonly used to describe this family of non-differentiable functions that are infinite in length. Find out more about their origins and history.

**Peter Landshoff**explains.

**Mike Yates**looks at the life and work of wartime code-breaker Alan Turing. Find out what types of numbers we

*can't*count and why there are limits on what can be achieved with Turing machines.