Rip, it will be recalled from the fable told by Washington Irving in 1819, was a thriftless, hen-pecked husband who liked a drink. One day he wandered up a mountain in the Catskills in search of game. There he met some strangely dressed people who gave him some peculiar wine which made him drop fast asleep.
When he woke the following morning, his gun was rusty and his dog had vanished. On descending to his village, he found that everyone he had known was dead (including, to his relief, his nagging wife). Two decades had passed. A war had been fought. He had gone to sleep a subject of George III and awoken a citizen of the United States.
This story is going to come true countless times - not on magic mountain- tops but in spaceships. Einstein's 1905 special theory of relativity predicts that what happened to Rip will happen to all astronauts who travel at close to the speed of light. Not only will they age much more slowly than the stay-at-homes. They will also be able to make a great deal of money out of doing so.
What if Rip, instead of being an idle frequenter of inns, had been a keen businessman who knew in advance about the properties of magic mountains. Suppose that before climbing the mountain he had invested pounds 100 at compound interest at a rate of 11 per cent - a reasonable rate to expect since he would undertake not to touch it for 20 years. On his return he would find that his capital had appreciated by 800 per cent. Together with his original investment, he would now have pounds 900 in his pocket.
Were he to repeat this exercise 10 or more times he would become vastly richer than Bill Gates. By the end of the 20th century, he would be only 12 days older, but his village would be 240 years older. His original pounds 100 would by then have turned into more than pounds 7 trillion.
While researching my book over the past three years, I read many varied and interesting opinions about manned flights to the stars, the ultimate goal of space travel. What is particularly interesting are the incredibly naive predictions about who is going to pay for these trips, and why.
Many experts assume that governments on Earth will finance them. This is absurd. Why should governments pay people to fly off to distant planets where they cannot be taxed? For national prestige? Surely not. Interstellar flight is a long-term project, and any such prestige will accrue long after any politician who supported it has left office.
What, then, of interstellar trade? Apart from tourism, trade is the main motive for intercontinental travel on Earth. But this will not work either. Maybe fabulous new minerals will be found on a planet circling Alpha Centauri. But our local asteroids bear many minerals: why go so far for what can be got so near at hand?
For science, or for adventure? No doubt many voy-ages will be undertaken for these purposes, but they cannot provide the finance needed for regular scheduled voyages, year after year, like a sort of cosmic British Airways.
Instead, imagine a man who invests part of his money at compound interest, goes off to Alpha Centauri with a large party, establishes a thriving colony there, and returns alone to collect his accumulated wealth.
Being now extremely rich and still relatively young, he can finance a second expedition to another star, and so on. Einstein's discovery will have created a new kind of capitalist.
Adrian Berry is the author of `The Giant Leap: man- kind heads for the stars' (Headline, pounds 18.99)