E Jane Dickson: Immortality isn't all it's cracked up to be

The future ain't what it used to be. Those of a certain age will remember exciting predictions that by the year 2000, we would all be hurling round on monorails, dressed in tinfoil and popping pills for dinner. OK, so the tinfoil trousers never caught on, but in the age of the Docklands Light Railway and nutritional supplements, the crazy dreams of the last century seem endearingly modest. It is perhaps no accident that, as the global economy crashes and the ecological Doomsday scenario gathers momentum, futurists have upped their game. This week – a big week for breakthroughs – we heard the soothing news that immortality is finally within our grasp. If we can just hang on in for the next 20 years, we can live for ever. Possibly on the Moon.

The man promising eternal life is not your average wild-eyed cultist. He is Ray Kurzweil, the American inventor of the speech synthesiser and a prominent, though not unquestioned, figure in the field of artificial intelligence. According to Kurzweil, the advance of technology is not linear, but exponential. By analysing how far we have come, we can predict how far and how fast we will progress. "I believe, he says, "that in around 20 years we will have the means to reprogram our bodies' stone-age software so we can halt, then reverse ageing. Then nanotechnology will let us live for ever."

There is, of course, a considerable gulf between theoretical science and its universal application. God knows the non-theoretical stuff is problematic enough. Video recorders have been round for more than 20 years and not all of us know how to work them. But even if, for the sake of argument, immortality were technically possible, what would we do with it?

There are certain obvious implications. If age does not wither us, how will we fit the extra candles on our birthday cakes? How will we fit the extra people on the planet? (Indeed, if nobody ever dies, is it desirable – or even possible – for new people to be born?) There will be no clear way of knowing when female newsreaders on the BBC have passed their sell-by dates. And how hard will we kick ourselves if Margaret Thatcher makes a comeback, aged 103, and leads the Conservative Party to victory in all eternity? I'm not quite doomy enough to agree with Schopenhauer that "to desire immortality is to desire the perpetuation of a great mistake", but there are downsides.

Our fascination with the notion of eternal life is instinctive and atavistic. Every morality tale we tell ourselves, from the grail legend to science fiction (not forgetting most world religions), is wound about the notion of human mortality. Death is traditionally the leveller, the absolute against which all else is measured. Take away that absolute and you take away the reason, or at least some good reasons, for living.

Mythology, at least, supports the idea of immortality as a reward for good behaviour. Immortality as a market commodity is a modern twist and another reason to fear Kurzweil's brave new world. Humanity's record on deciding who gets to live and who gets to die is not good. The week's more immediately useful breakthrough in the development of a vaccine against HIV is already clouded by concern over how the benefits will be distributed. If the free availability of the antiretroviral drugs that slow the progression from HIV to full-blown Aids is any kind of model, sub-Saharan Africa, home to two-thirds of the world's Aids-affected population, will be a long way down the queue.

If life-preserving drugs are handed out according to personal wealth or GDP, what price the immortality process? Kurzweil assures us that affordability keeps pace, or at least follows close on the heels of technological advances. My guess is that nanobots (the structures it is claimed will replace blood cells and enable us to write books in minutes and sprint like Olympians for 15 minutes without drawing breath) will remain a "premium product".

A world where only the poor grow old and die is not most people's idea of progress. And it's a short leap to the Huxleian nightmare of a New Order where the young and lovely are serviced by a subspecies of ageing drones. (Anyone who has ever ventured into Topshop with a teenage daughter will recognise the horror.)

The desire to live for ever is the existential scream of the ego. And we live in a society that has, as it were, given ego its head. Today, immortality is a theoretical possibility. Tomorrow, we will surely demand it as our "right". Yet Kurzweil admits that "the final frontier" is still a way off. If we've got the demographics right, there are going to be a lot of old people around in the next 20 years. We may even be among them.

We need to fight down the herd panic on the issue of ageing and its natural consequence. Because immortality is not the answer. It is the only and original fate worse than death.