Overview: CHRIS SERLE, IAN MCNAUGHT-DAVIS and GILL NEVILL continue their exploration of the world of information science. 7: Let's Pretend: Training space-shuttle pilots, or testing bridges to destruction, is normally too costly or too dangerous to do on the real thing. But by giving a computer an exact description of how a complicated system behaves, it can mimic anything from the British economy to the world's weather.