简答题:Although most science fiction is not predictive, it can still be a guide to the future, says Tom Standage. In the beginning of 2020, the upheaval of Brexit means the prospect of Irish reunification no longer seems like science fiction. But despite popular perceptions to the contrary, such forecasts are the exceptions, not the rule. The fact that sci-fi is often set in the future does not mean that it is intended to be predictive. More often it is a commentary on the present. However, stories of this kind do seem to enable us to touch future, to a certain degree. Apart from aliens and spaceships, much contemporary science fiction is concerned with themes such as the impact of artificial intelligence, the danger of ecological collapse, the abuse of corporate power and so on. Since the sexual revolution in 1960s, it is pretty prevailing that sci-fi writers have explored the changing attitudes to gender politics, for example, future societies in which gender is irrelevant or people can change sex at will.