Issue 15

June 2001

What is the best strategy when playing backgammon? How big is the Milky Way? And which numbers cannot be created using just elevens and sevens? Find out all this and more in this issue.

Backgammon is said to be one of the oldest games in the world. In this article, Jochen Blath and Peter Mörters discuss one particularly interesting aspect of the game - the doubling cube. They show how a model using Brownian motion can help a player to decide when to double or accept a double.
Knots crop up all over the place, from tying a shoelace to molecular structure, but they are also elegant mathematical objects. Colin Adams asks when is a molecule knot a molecule? and what happens if you try to build a knot out of sticks?
A question which has been vexing astronomers for a long time is whether the forces of attraction between stars and galaxies will eventually result in the universe collapsing back into a single point, or whether it will expand forever with the distances between stars and galaxies growing ever larger. Toby O'Neil describes how the mathematical theory of dimension gives us a way of approaching the question.
Claude Shannon, who died on February 24, was the founder of Information Theory, which is the basis of modern telecommunications. Rachel Thomas looks at Shannon's life and works.

Suppose you have an infinitely large sheet of paper (mathematicians refer to this hypothetical object as the plane). You also have a number of different colours - pots of paint, perhaps. Your aim is to colour every point on the plane using the colours available. That is, each point must be assigned one colour.

Steve Traylen tells Plus about life as a Systems Administrator.
Count up your booty of jewels and potions!
This CD ROM, produced by the Centre for the Popularisation of Mathematics at the University of Wales in Bangor, is a most unusual mixture of mathematical exposition and modern art. A central part of the content is a gallery of sculptures by John Robinson, much of whose work takes inspiration from mathematical objects, such as fractals and knots. This work, described by the artist as symbolic sculpture, uses forms such as the logarithmic spiral, and makes connections with the forces that shape our universe.

This beautifully illustrated book by the world's leading authority on African mathematics provides us with a wide-ranging introduction to mathematical intuition in sub-Saharan African cultures. These cultures are extremely diverse and expressive in their creation of designs and motifs that embody geometrical and topological ideas. No one is better qualified to tell us about it than Paulus Gerdes, who has lived and worked in Mozambique for many years.

"As Obi-Wan Kenobi said about the Light Sabre in Star Wars IV, a slide-rule is an ancient weapon from a more civilised age," state Chris Budd and Chris Sangwin in their book, Mathematics Galore, soon to released by Oxford University Press. The book digs up the slide-rule and a few more historical artefacts, as well as the art of country dancing, to present a pick-and-mix bag of mathematical ideas for the aspiring mathematician or the mathematically inclined general reader.