Ever since characters in Star Trek started to dash through the cosmos at many times the speed of light, people have wondered whether astronauts will ever do this in real life.

The dream is that some 30,000 years hence, we shall be sufficiently advanced in technology to build among the countless stars of our Milky Way galaxy a ‘galactic empire’ in which people would live on millions of worlds. They would travel the tens of trillions of miles between one world and another in no more time than it took seagoing voyagers to cross Earth in the last century.

But alas, apparently, for this imperial dream. Any speed faster than light, 670 million mph, appears to be forbidden by Albert Einstein’s special theory of relativity of 1905. At that speed, according to his gloomy equations, any further acceleration would require an infinitely powerful engine. Since such an engine could never exist, it seems that faster than-light travel and galactic empires are prohibited.

Not necessarily so, says Kip Thorne, a professor of theoretical physics at the California Institute of Technology. For Einstein published a second set of equations in his much more subtle and complex general theory of relativity of 1916, which says that matter creates the space and time which surround it – rather like a statesman alighting from a plane and causing a red carpet to unfold before him.

This in turn indicates that space is not an empty vista of nothingness, but has its own elastic, or warped character. (The word ‘warp’ already brings us nearer to Star Trek.) A large mass, such as a star, causes space to curve in its immediate surrounding region. This raises the possibility that a spaceship could disappear in one part of space and reappear immediately in another, without passing any point in between.

Why? Because at the submicroscopic level, according to the 1916 equations, space turns into a kind of ‘foam’. At the smallest distance that can physically exist, roughly on the scale of a billionth of a trillionth of a trillionth of an inch, space is permeated like a Swiss cheese with interconnecting tunnels, or ‘wormholes’.

There would thus be two ways to travel the twenty-six light years between Earth and Vega: you could take either the long route of 156,000,000,000,000 miles, or, through the hole, a journey so short as to be virtually instantaneous. Through a wormhole, in other words, if one could make oneself small enough, one could travel across light years through the hidden dimension – so common in science-fiction stories – of ‘hyperspace’.

Thorne, a highly conservative scientist, had long ignored such speculations. Then, in 1987, he had a phone call from his colleague Carl Sagan, who was having difficulties with the technical side of his SF novel Contact. Could Thorne advise him how his how his heroine Eleanor Arrowlee could plausibly get from one planet to another faster than a light beam?

The professor forgot his scepticism and became sufficiently intrigued to study the problem in detail. The conclusion was that it might be possible to enlarge the diameter of a wormhole sufficiently to allow a spaceship to pass through it. Although the technology needed to do this was ‘as much beyond present human capability as space travel was beyond that of cavemen’, he saw how it might be done. The hole would be ‘threaded’ with a substance called ‘exotic matter’ which would force it open – rather as people who buy nylon socks poke their hands into them to enlarge their diameters before putting them on.

Surprisingly, all this is told very simply, and any reasonably attentive layman should have no difficulty in grasping the argument. For those who stumble, there is an excellent glossary. My only criticism is that the conclusion is somewhat vague. A wormhole traveller might turn up in a distant part of the universe simultaneously like Captain Kirk and his colleagues, or he might find himself travelling backwards in time. And he would then have to solve the perplexing problem of what would then happen if he murdered his parents before they met.

But such minor difficulties will no doubt be solved before we are in a position to say: ‘Warp nine, Scotty.’