It is powered by a device similar to that found in a microwave oven

at the equivalent of 450 million miles an hour

Anyone who has ever watched an episode of Star Trek or a Star Wars film will know how it works.

The good guys are minding their business in outer space when suddenly the Klingons or the Dark Empire bear down on them out of nowhere.

There is only one way out. At the flick of a switch, our heroes are flashed — in a blur of passing stars — to safety elsewhere in the universe.

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U.S. space agency Nasa is thought to have successfully tested a revolutionary new power source - which will enable something akin to Star Trek's 'warp speed', cutting down flying times from days to hours

Call it warp drive or a hyper drive, it adds up to the same thing: a miraculous power source that allows a spacecraft to fly at unimaginable speeds.

But while it’s so far confined to the realms of sci-fi, the concept could become reality.

U.S. space agency Nasa is thought to have successfully tested a revolutionary new power source that could enable spacecraft to travel to the Moon in just four hours instead of more than three days and to Mars in two or three weeks instead of seven months.

Compact enough to fit into a suitcase, this whizzy new device could — it is claimed — keep flying for eons, at the equivalent of an astonishing 450 million miles an hour.

Load up the spacecraft, we’re all off for a long weekend on Venus!

The invention fuelling such hopes is called an electromagnetic drive or EmDrive — and it’s powered by a device similar to that found in a microwave oven.

It was invented by British scientist Roger Shawyer, who has endured years of ridicule since he unveiled it nearly a decade ago.

Critics insisted his invention was a scientific impossibility because it broke one of the basic laws of physics governing the universe.

This rule is Sir Isaac Newton’s third law: that if you push in one direction, you accelerate in the opposite.

Indeed, every rocket engine ever made has fired burning rocket fuel out behind it, thus powering the craft forward.

But the EmDrive doesn’t use a propellent. It works by converting electric power — from solar panels or a small on-board nuclear reactor — into forward thrust. According to some scientists, it is the ‘impossible drive’.

The scepticism, however, hasn’t stopped EmDrive’s development rights being bought by aircraft giant Boeing and the UK Government funding the early development of Mr Shawyer’s ideas.

The new system is powered by a device similar to that found in a microwave oven, and, if successful, could revolutionise space travel - something which will no doubt delight space tourism entrepreneur Sir Richard Branson (pictured with Arnold Schwarznegger and a model of one of his spaceships)

Now retired, he acts as a consultant to a British company that is continuing the research, and he says other countries are developing similar designs. In fact, five years ago the Chinese claimed they had built an EmDrive and proved it worked — but no one believed them.

It’s harder to be sceptical when the news comes from Nasa — an organisation that put men on the Moon and sent rockets to Mars.

According to Nasa engineer Paul March, it has conducted the first successful tests of an EmDrive in a vacuum, to recreate the emptiness of outer space.

Some suggest the EmDrive is set to become one of many wonderful British inventions which — for lack of investment and vision — end up being hijacked by someone else.

Examples of this lamentable tendency include the tank, the jet airliner and the programmable electronic computer.

When I tracked down Mr Shawyer to his base in Havant, Hants, he said he was pleased Nasa was ‘having fun’ with his creation and felt some vindication after years of scepticism.

That said, he seemed a bit peeved that the Americans were grabbing all the attention.

An aerospace engineer who worked for the Galileo space project to build a European satnav system, Mr Shawyer unveiled his idea in 2006.

He promised it would not only speed us to new galaxies, but ‘put an end to wings and wheels’ by making traditional forms of transport redundant.

His prototype looks like something sci-fi writer Jules Verne might have dreamt up to blast Victorians to the Moon.

The invention works by converting electric power — from solar panels or a small on-board nuclear reactor — into forward thrust

But Mr Shawyer says: ‘There’s no magic in it. It fully complies with the laws of Newton, Einstein and [Scottish physicist James] Maxwell. You need to understand microwave engine-ering, which a lot of people don’t. But the physics behind it is pretty straightforward.’

It was Maxwell who worked out in the 1870s that light exerts a force on any surface it hits, like wind on a sail.

But that force tends to be tiny, unless you can amplify it. Mr Shawyer says he did just that. Experimenting with microwaves, which behave in a similar way to light waves, he used a magnetron — a device found in microwave ovens — to bounce them back and forth between the ends of a closed tube.

His crucial discovery was that if you make one end of the tube wider, they exert more pressure on the other end, thereby pushing the whole thing forward. Nasa researchers claimed when lasers were fired into their EmDrive’s chamber, some of them travelled ‘faster than the speed of light’, suggesting it could power a craft at the same velocity.

Mr Shawyer is sceptical, saying he believes such speeds are impossible.

The imagination is your only restraining factor. Once you no longer have to carry fuel with you, the possibilities are immense Inventor Roger Shawyer

He also explains that the EmDrive accelerates gradually but continuously as long as you keep powering it with electricity (via solar or nuclear power).

Its inventor calculates that an interstellar probe would take ten years to reach two-thirds the speed of light, which he sees as pretty much the limit of how fast we could practically travel.

(The effects of such speeds on the body aren’t clear, but this steady increase in pace should avoid subjecting astronauts to dangerously rapid forces of acceleration.)

Still, that’s an astonishing 450 million miles an hour.

‘The imagination is your only restraining factor,’ says Mr Shawyer. ‘Once you no longer have to carry fuel with you, the possibilities are immense.’

Mr Shawyer is more excited about EmDrive’s potential to save this planet rather than reach new ones.

Never mind the HS2 rail link — he sees transport revolutionised as planes, trains and cars are replaced by craft that can whisk us from London to Sydney in a just a few hours by flying most of the way in the outer limits of our atmosphere.

‘The most important thing is that EmDrive is green, convenient and will change our world in the next few decades,’ he says.

‘Ye cannae alter the laws of physics,’ wailed Scotty, chief engineer aboard Star Trek’s USS Enterprise, whenever Captain Kirk asked him to push it to the limit once more. Perhaps he was right.