At the beginning of the last century, near the end of his tragically short life, James Elroy Flecker addressed these words "to a poet a thousand years hence": I care not if you bridge the seas,
Or ride secure the cruel sky,
Or build consummate palaces
Of metal or of masonry.
Well, we may not have bridged the seas, but millions now ride secure the cruel sky. And how astonished Flecker would have been to know that, a mere half-century after his death, men were preparing to go to the moon. That alone should prove how futile it is to attempt predictions about the world even a few decades ahead, let alone in the year 3001. For how successful would a survivor of the battle of Hastings - the only date most British people remember from their school days - have been, had he been asked to describe how we would be living nearly a millennium later? Even two centuries ago that would have been an impossible task because virtually everything that shapes the modern world has been invented - or discovered - since 1800. And now with the arrival of the microchip - the most important invention since the wheel - we are faced with another major discontinuity. But first let us consider a rather fundamental question, not as ridiculous as it may seem. Will Britain still exist in the year 3001? I don't mean politically - I mean physically. One thing is certain: the British Isles won't be where they are now. Plate tectonics (aka continental drift) will have moved them approximately 20 metres eastwards. But that is the most favourable scenario, for it has only recently been realised that we live in a dangerous universe. There were four major asteroid or comet impacts in the past century, luckily in uninhabited parts of the globe. In September, the Earth had a near-miss from an asteroid 500 metres wide; if the rock had hit, the explosion would have been millions of times as powerful as the atom bomb over Hiroshima. The scarred face of our next-door neighbour, the moon, shows how frequent collisions have been in the past. And these are not the only nasty surprises Mother Nature could spring on us. If a couple of neutron stars collide within a few thousand light years of the solar system, the resulting blast of x-rays and gamma rays could be lethal to all forms of life except those in the deep ocean. Of course, whether such catastrophes are a good or a bad thing depends on one's point of view. If the Earth had not received a major hammer blow from space some 65m years ago, an unpretentious little rodent-like creature might never have had a chance of going on to greater things. One of my colleagues put it in a nutshell when he said: "The dinosaurs became extinct because they didn't have a space programme." Nor, to be honest, do we have much of a space programme at the moment: our current ventures beyond the atmosphere will one day look like early 19th-century attempts at ballooning. In fact, that is a good analogy, because the rocket may play exactly the same role in space exploration as the balloon did in the conquest of the air. It is only a matter of time - I trust not more than a few decades - before we have safe and economical space propulsion systems, depending on new principles of physics that are now being discussed by far-sighted engineers and scientists. Nasa has established an Institute for Advanced Concepts to look into such matters. It is not generally realised that space travel requires only trivial amounts of energy compared with jet flight in the Earth's atmosphere. The awesome power and violence of a Saturn V launch, where thousands of tons of fuel were required to take three men to the moon, is a spectacular proof of our current incompetence. When we know how to do it efficiently, the main expenses of space travel will be catering and in-flight movies. (Passengers cannot be expected to spend all their time looking at the stars, or reading that popular guide to zero-gee, the Nasa Sutra.) So the exploration -...