Ketchup and traffic jams: the maths of soft matter

The class of materials known as soft matter - which includes everything from mayonnaise to molten plastic - is the subject of the inaugural lecture by Michael Cates, Cambridge's Lucasian Professor of Mathematics. Having now understood what's going on in these active systems, we hope to design better versions that can be used to create a wide range of new materials - Michael Cates Good things come to those who wait - according to a marketing slogan for Heinz ketchup from the 1980s. But why is the ketchup so difficult to get out of the bottle? The reason is that ketchup is in two minds: whether to pour like a liquid or stay put like a solid. It is one example of soft matter - a huge class of materials which behave in complex and nonlinear ways. We interact with soft matter every day: toothpaste, chocolate, shampoo and mayonnaise are all examples, which can behave either as liquids or solids depending on the circumstances. Soft matter can also be found in laptop screens, advanced batteries, and in the processing of functional ceramics and plastic LEDs. Cambridge researchers have developed new mathematical models to describe why these materials behave the way they do, which could help improve them for both domestic and high-tech applications.