**Kevin Jones** investigates the links between music and mathematics, throwing in limericks, Fibonacci and Scott Joplin along the way. *Plus* is proud to present an extended version of his winning entry for the THES/OUP 1999 Science Writing Prize.

Is the Universe finite, with an edge, or infinite, with no edges? Or is it even stranger: finite but with no edges? It sounds far-fetched but the mathematical theory of topology makes it possible, and nobody yet knows the truth. **Janna Levin** tells us more.

Underlying our vast global telecommunications networks are codes: formal schemes for representing information in machine-readable and transmissible formats. **Kona Macphee** examines the prefix property, one of the important features of a good code.

**Robert Hunt** concludes our Origins of Proof series by asking what a proof really *is*, and how we know that we've actually found one. One for the philosophers to ponder...

**Helen Thompson** works for Sainsbury's Supermarkets as a Sales Forecasting Manager. The Plus team paid her a visit at Drury House on the banks of the Thames in London.