Chaos theory serves up solution to speedy defrosting in microwaves

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The Independent Online

Chaos theory, the branch of science which came to prominence in the 1980s and made famous the idea of systems whose outcome could not be predicted, has found an application - in the humble kitchen microwave.

Machines now on sale include a "chaos defrost" setting, which generates an irregular heating sequence that can cut the time needed to defrost food by up to 60 per cent, Professor Jaroslav Stark, of the mathematics department at Imperial College in London, has found. "It came as quite a shock," he notes in the journal, Science. "Even the most practically minded scientist, let alone a mathematician, rarely expects to see a connection between their research and their kitchen."

The application, being used in new microwave ovens made by Panasonic, was first discussed in 2001. But Professor Stark also said "it is surprising that [chaos theory] has taken so long" to be used in practical applications, since the theory was first discussed in the 1960s.

The "chaos defrost" system blasts the frozen food with strong, but near-random blasts of microwave radiation, rather than using weaker, constant power. The new approach means the food is heated more evenly and thus defrosted more evenly and quickly, because local pockets of warmed food will help thaw any adjacent frozen volume. The older method leads to large areas which are thawed and other large areas that are still frozen, which is a health risk.

Chaos theory describes nonlinear systems where variations in starting conditions lead to unpredictable results. Initially, it seemed that it was simply an interesting branch of mathematics but Professor Stark says there are now a variety of potential applications.

Chaos theory made an important contribution to the control of the foot-and-mouth epidemic in 2001, while spacecraft trajectories - which are classic candidates for chaotic outcomes, because there are so many forces operating on them - are now calculated using non-linear maths, which has enabled missions using the minimum of fuel that would have been impossible using traditional mathematics.

Production lines, whose output can fluctuate unpredictably when one part is busy while another is idle, could be analysed using chaos theory to run more stably, he says. And doctors are using the same branch of mathematics to model blood flow after complex heart operations to help decide the best way to perform the surgery in future.

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