Networks and how they behave

Professor Ian Stewart, the bestselling author and mathematician, is currently giving a series of public talks in Malta. Professor of Mathematics at Warwick University, he was awarded the 1998 Communications Award of the Joint Policy Board for Mathematics in the USA for popularising mathematical and scientific topics through books such as Does God Play Dice?, From Here to Infinity, The Collapse of Chaos and The Science of Discworld.

Professor Stewart be giving a public lecture on "All the World's a Network" for the Malta Mathematical Society on Wednesday at 6.30 p.m. at St James' Cavalier, Valletta.

The talk will be highly illustrated and will avoid mathematical technicalities. It will describe some of the exciting research currently being done on the dynamics of networks, concentrating on applications to biology.

Networks, and how they behave, have been propelled to the forefront of today's science. An epidemic is a disease that spreads through a network of people, linked by their contacts. The Internet is a network of computers, linked by phone lines. Mobile phones rely on networks of base stations. Living creatures function because of networks of genes and their interactions, ecosystems are driven by predator-prey 'food webs', and the brain is a gigantic network of neurons.

Even simple networks are remarkably versatile, and can be very puzzling. Scientists desperately need to understand how networks behave, but only recently have some of the basic principles been understood. A prominent example is the 'small world network', which explains old experiments showing that 'six degrees of separation' link any two people on the planet. The Kevin Bacon game (link actors together by films in which they have both played, with a link to Kevin Bacon as a final step) relies on the same phenomenon.

Patterns of animal movement (walk, trot, gallop) involve a more general kind of pattern, synchronisation with a time delay. When people walk, the left leg does the same as the right leg but half a cycle later. A trotting horse synchronises diagonally opposite legs, with a half-cycle delay between the two diagonals. These patterns arise because of the form of the network of nerve cells that generates the basic rhythms.

Finally, the formation of new species can be understood in terms of a network of interactions among the members of the species.

Further information on all talks by Ian Stewart is available at the Department of Mathematics Website www.maths.um.edu.mt