Scotland to Sydney in 17 minutes? Mars in 1.5 days? It could happen thanks to the engineer Sandy Kidd's anti-gravity invention. Stuart Bathgate meets the man who British Aerospace are at last taking seriously.

In 1903 the eminent American astronomer Simon Newcomb "proved" on paper that heavier-than-air flight was a mathematical impossibility. Later that year the Wright brothers flew at Kitty Hawk.

This gap between accepted scientific theory and reality is all too familiar to Dundee-based engineer Sandy Kidd. In a book published this week, Beyond 2001, Kidd provides a fascinating account of the process that eventually led to his producing a self-propelling gyroscopic device - the Kidd machine - which, it is said, will revolutionize the laws of physics. In particular, Kidd's claims that Newton's Laws of Motion - sacrosanct for centuries - do not hold true for all instances.

The machine's value though, is not just theoretical. Employing constant acceleration, it could shrink the solar system. Traveling to Mars would take a day and a half. Neptune - some seven years distant by rocket - would be reached in under a fortnight

Distances on Earth too, could become meaningless: instead of commuting by rail from, say Linlithgow to Edinburgh, a journey of 15 minutes, the owner of a Kidd machine could travel to work daily from Sydney - it would only take two minutes longer.

All this is possible because of what is known as 'anti-Newtonian lift'. The classical physics dictum that "every action must have an equal and opposite reaction" is observable in everyday life: you can only jump into the air by first pushing down on the ground; a rocket can escape our atmosphere only by producing a phenomenal thrust. Yet Kidd's machine does not require thrust to lift itself into the air. It is not lifted by aerodynamics. It does not depend on a hot-air cushion. Incredible as it sounds, Kidd's machine rises by losing weight.

"Taking angular momentum and turning it into linear momentum without a reaction is just not allowed," says Kidd - "but that's what my machine does."

Needless to say, since that night in 1984 when he first got the machine to work in his own garage on the outskirts of Dundee, reaction from the academic world has been almost universally hostile. At first, the tactic was to laugh it off, with the claim that Kidd was spinning a yarn, not a gyroscope. Then, various, increasingly desperate, attempts were made to prove that Kidd's device, did, after all, conform to the known laws of physics. None of them have been successful.

Now, six years on, with the publication of 'Beyond 2001', and of an independent laboratory report on his machine, Kidd says that it is time for the academics to put up or shut up. "They just want to think that if they jump up and down and tear their hair out I'll admit I'm a liar. A lot of them are like children when you've taken away their toys. It really gets to them. How can this unqualified nitwit make this machine?"

It's a refreshingly honest self-description. Kidd realizes all too well the apparent uncertainty of the situation: an engineer with no academic training potters about in his shed, cannibalizing washing machines and lawn-mowers for spare parts until he stands accepted physics on its head.

His interest in the entire project began, he says, in the air force. "There were a lot of times with nothing to do, times of boredom when you just lie in your pit and ask 'Who am I? Why am I here?' - all these two-steps-to-the-loony-bin questions. So you had to find some other interest. In my case, I honestly believed that man would find an alternative means of space travel."

It was the very fact that Kidd had not been 'brainwashed', as he puts it, by an academic training, that led him to ask the right questions in the first place. He also has an implicit awareness of the importance of the old saying, that the greatest wisdom of all is to appreciate the depth of your own ignorance.

"When I hear scientists say we know all there is to know about the laws of physics it annoys me. How can they be so arrogant? We don't have a clue. Nobody's ever seen an electron. We don't know what gravity is. We don't know what inertia is. We only scratch the surface."

Events have moved on apace since the successful lab tests with which the book concludes. Whereas previously Kidd had achieved the lifting effect without knowing how strong that effect could become, in the last six months, he says, "I have proved it can be as good as you want it to be. It's only limited to the strength of the material."

Of equal importance is the fact that he now knows why the machine works - not only because it will help to make technical advances, but also because his wife Janet - "I couldn't have done any of this without her" - is threatening to leave him if he doesn't stop constructing new, improved models. "She said that years ago," says Kidd, trying to laugh off his wife's assertion. "Aye, but I mean it this time," she replies.

The Kidd machine works for reasons entirely different to those he first thought of, although clearly, with the enormous potential involved, he is not about to divulge those reasons to the general public. "Let's just say that a physicist or mathematician who isn't brainwashed or hidebound will be able to look at the machine and accept that my explanation for why it works is correct."

If anyone is still skeptical, Kidd is willing to stake more than personal pride on the veracity of his claims. "I'm prepared to bet my house against their house," he says. "All those academics can take me up on that if they still refuse to believe me. They'll be furious when the book comes out - and the more fury the book raises, the happier I'll be - but I doubt if any of them will take me up on that bet."

There is a theory of scientific advancement known as "steam-kettle time" which asserts that once the conditions are right, a certain invention is more or less inevitable.

Scattered around Europe and North America are dozens of people working independently on the same project. At least two others, Kidd thinks, have achieved anti-Newtonian lift. "A lot of people have been working on 'anti-gravity devices' for the same reason as me," he says. "The rocket is a crude, inefficient, dangerous device. There has to be a better way."

Now the timescale for commercial development of that better way is "directly proportional to the wallet - it all depends on how much money someone is willing to put into it." While it was announced yesterday that British Aerospace will help fund further tests, the Australian company BWN with whom Kidd has worked for several years will retain a keen interest in the device's development: the engineer will soon return to Australia, with his wife, to supervise more research.

Kidd's device, then, is an idea whose time has come. And, one might say paradoxically, not before time. Anyone who struggles for so many years to achieve what is said to be impossible, who perseveres despite the diverse difficulties detailed in Beyond 2001, must either be mad, or know that he is right. Sandy Kidd is not mad. Very soon now the final verdict will be delivered.

- Beyond 2001: The laws of physics revolutionized, By Sandy Kidd, with Ron Thompson, is published on Thursday by Sidgwick and Jackson, 14.95

(contributed from Scotland on Sunday, 5-Aug-90)