On 11 August 1999, everyone knew that a total eclipse of the Sun was going to take place and exactly where you had to be if you wanted to experience it. It had been predicted by astronomers for decades. It is thanks to the work of Isaac Newton that the movements of the Sun, Moon and Earth are known so predictably. In fact for a long time after Newton, people thought that everything in the Universe was just as predictable. But the Second Law of Thermodynamics put a bit of a spanner in the works of the clockwork universe. Everything, the Second Law insists, must gradually become more disordered. Anything that actively increases order, such as spending half an hour tidying the house, has the inevitable consequence that disorder will increase elsewhere in the Universe. You generate heat by working, as does the power station generating electricity for the vacuum cleaner. This ever-increasing disorder, or entropy, is inescapable.