In the old days of science fiction movies, in the fifties, say, the future was portrayed as clean and antiseptic and functional. Technology had won, and society had become well ordered and safe. And to demonstrate this, most of the actors had to stride around stark scenery wearing helmets. Shiny helmets, usually.

In the late seventies and early eighties, two films came along that went in a completely different direction: Alien and Blade Runner. In both cases the future was portrayed as a messier, dirtier version of now. Technology had certainly arrived, but it didn't always work, and it was indifferently maintained by people who obviously preferred to be somewhere else. Ridley Scott, who directed both, said that Alien was about "truck drivers in space."

Scott also brings his unique visual sense to Blade Runner, and the visuals are responsible for much of the film's enduring appeal. Two decades after it came out, it still looks amazing. It has atmosphere. It has atmosphere in bucketloads. And moving within it are interesting people and interesting robots. Sometimes they struggle to make sense of their world and their place in it, and sometimes they don't bother. Either way, there's a sense that they are able to accept it for whatever it is. And it's a world of individuals, not a seamless, helmet wearing society. That's what's really prescient about Blade Runner: it assumes that the world is not going to be perfect any time soon, or even any simpler.

Early in the film there's a great scene in which Harrison Ford, playing Deckard, is reading a newspaper on a crowded street. He's in Chinatown, it's raining, and night has fallen. It's always night in Blade Runner: the film opens with a panoramic view of a darkened Los Angeles, and daylight never comes. Just for a moment we have no idea why Deckard is reading a newspaper, or why he's doing so here, but then we realise he's waiting for a stool at a hawker street stall across the way.

When one becomes available, he's beckoned. He crosses the crowded street, using the newspaper to protect himself from the rain, and sits down. He orders something, and, as an afterthought, adds two words: "with noodles." Not long after they arrive, a sinister figure appears and requests his presence elsewhere. They get into a car. It lifts off. For a moment Deckard gazes out at the immensely complex cityscape spread out below him, and then he turns his attention to more mundane matters. He keeps eating his noodles.

This one tiny moment is one of my favourite film images. It presents a vision of the future, and it's one that seems plausible. Blade Runner's city of the future has dirty streets, with technology hovering overhead, and it's always raining. And out of the dense crowd come suspicious characters with unknown motives. And, above and beyond all this, there are still noodles.