Today being yesterday's sci-fi, just how did they get it so wrong?

There are fashions in futures as in all other things. The point has been brought home in the past few weeks by a couple of things - the Seventies revival in fashion itself, and by the final episode of Absolutely Fabulous, a comedy with a curator's eye for the bric-a-brac of contemporary chic.

Imagine a film designer in 1976 trying to create an impression of the millennial threshold, that almost unimaginably distant time a full generation away - well past the long-standing marker post of 1984; imagine the effort taken to make the future look attractively estranged from the scuffed, ordinariness of the present. And yet when the designer finally arrives at the imagined destination what does she find? A television fashion show in raptures over floral-printed chiffon trousers and vicuna tank tops, and a kitchen setting in which the epitome of modern chic is a 1940s Dualit toaster.

If I'm remembering the future correctly, the Seventies saw it mostly as a place of minimal interiors and shiny fabrics, a time when button- fronted jeans would have been consigned to museums, but their future turns out to be much closer to home.

Our future has moved on, naturally. These days, having got wise to the magpie tendencies of general culture, most designers depict the future as a violent cross between a jumble sale and a costume party - a bring- and-buy sale lit by the flames from burning cars. That's the dystopian version, which is to say the most fashionable version, and while it is still possible to see examples of technological optimism - holographic valets in a toothpaste commercial, for example - there is usually something self-mocking about the idea (the commercial in question is actually a double-bluff, a way of saying that this brand of toothpaste will one day obtain the status of an unimprovable classic).

It doesn't really make sense to say that any of these futures is "wrong" because prediction is never exactly the point. Our images of the past and the future are only ever ways of talking about the present, its anxieties and desires. And the idea that the fantasies might actually come true is a dreadful one, whether the vision is optimistic or not.

The writer William Gibson, himself the architect of a very influential brand of cyber-punk future, once wrote a story called The Gernsback Continuum in which a photographer starts encountering the mental residue of Thirties futurology while working on a project about futuristic architecture: "Ever so gently, I went over the Edge - And looked up to see a 12-engined thing like a bloated boomerang, all wing, thrumming its way east with an elephantine grace, so low that I could count the rivets in its dull silver skin, and hear - maybe - the echo of jazz."

This is sharp and funny about the Thirties fashion for hopeful extrapolation and about the blind spots that only time reveals - the stratocruiser gleams with thrilling novelty but it is still powered by propellers and it is still a jazz band that plays in its aerial ballroom. The story is also a sort of manifesto for Gibson's own science fiction, which strives to retain a sense of the impurity of life, the one historical certainty, that greed and failure and power will always play their part.

The photographer's visions are horrifying because of the evasion the Thirties airbrushed future represents. Overhearing two of its inhabitants talking outside their car ("an aluminium avocado with a central shark- fin rudder jutting up from its spine") he notes that they are "smug, happy and utterly content with themselves". I hope, though, that Gibson doesn't think himself exempt from the law which binds all imaginative time-travellers.

In 40 years' time his own brand of dystopian invention is likely to look just as quaint, just as guilelessly revealing about the times in which it was written. Where Depression America wanted a streamlined prosperity in its future - an aircar in every garage and food pills for all - we desire something more unnerving, a world in which comfort is hard-won and difficult to defend.

In truth, the only way to accurately enjoy the future - or at least its pleasures of strangeness and revelation - is to imagine yourself in the past and think about the present.

Of all temporal addresses the present is the least desirable (when people say "it will do for now", they have no very large expectations about how demanding "now" will be; "now" gets what it's given). But imagine yourself as an early Victorian for a moment and it takes on a different lustre. It isn't just that everything looks a bit less commonplace, that radio and television and mobile phones have their novelty and splendour restored to them. It's also that you can get some perspective on how alien the present is, even to those of us who never take a second glance at it. How would you explain to that Victorian that one of the most popular entertainments on the miraculous device in the corner of every living room was a weekly bulletin from a veterinary hospital, a programme that showed cats having infected wombs removed and dogs being put to sleep? How would you explain that traffic still moves at the same average speed as it did in the days of horse-power?

The future is now, and it is nothing like they thought it would be.