To Aldo Costa, the laws of physics are more like guidelines. This includes Newton's second law of thermodynamics, which decrees that perpetual motion is impossible. That hasn't stopped Costa, 79, from spending five decades and more than $200,000 of his own money trying to build a machine that will run forever on the "free energy" of interplanetary gravity. Other laws have gotten in the way, too, including the one French authorities cited to block construction of a 300-foot-diameter contraption behind his house in Villiers-sur-Morin. His working model, shown here, is 56 feet across. Then there's the law his wife and three kids used to deny him access to what's left of the family's savings. "They don't seem to understand what I'm doing," Costa says.

The retired mechanic and self-taught physicist fell for perpetual motion 50 years ago while fixing a wrecked car. During a test-drive, he noticed the car kept pulling to the right. The alignment was off. "If I hadn't pulled the wheel back, it would go forever and ever in a circle," Costa says. "I thought that if I could make this motion vertical, it would be like a motor." Voilà. Costa drew up plans for a giant unbalanced wheel. Working mainly by himself, he gradually hauled in more than 9.5 tons of steel parts to construct his model. Given an initial push, it can revolve for three hours - aided by the wind. He envisions full-scale versions transforming deserts into oases and breaking Big Oil's grip on the world. If only he had a perpetual money machine.