VOA标准英语2014--New Skateboard Defies Gravity（在线收听）

New Skateboard Defies Gravity

WASHINGTON— 

A futuristic dream only a couple of decades ago, the hoverboard – a skateboard that floats above the ground - has finally been made possible. While still not ready for mass production, it promises to become a cool mode of transport, at least over some surfaces.

Mutual repulsion between the same poles of two magnets can counteract the force of gravity, and make an object levitate or hover in space.

Since the 1980s, that principle has been employed in so-called maglev trains in Europe, Japan and China, that hover above the track. With no contact between the carriage and the surface, and hence no friction, maglev trains are almost noiseless and can move very fast.

Architect Greg Henderson, who founded the company Arx Pax with his wife Jill, said the same technology can make anything hover, even buildings.

“Imagine there's an earthquake and the early warning turns on the warning systems and the supports fall away as the building starts to hover. The shaking stops, the supports return, and no one in that room or in that building ever knew there was an earthquake," said Henderson.

As a proof of the concept, Henderson's company created the first maglev hoverboard, called Hendo, capable of holding a single person about 2.5 centimeters above a metal surface.

"We are creating a magnetic field, and then through a method of induction, that's part of our secret sauce, we are creating a secondary and equal magnetic field in this conductive surface," explained Henderson.

For now, batteries that power Hendo's four engines last only for a short time, but design engineer Kyle O'Neil said for experienced skateboarders, it is enough to learn how to control the hoverboard.

“Some people say it's like snowboarding. Some say it's how they imagined a hoverboard is supposed to be, which is kind of an interesting response because no one's ever ridden one before,” said O’Neil.

Hendo’s creators say they do not expect to see their hoverboard on the streets anytime soon, because it only works on a metal-covered surface. But they say larger hover engines could be used for transporting containers, for instance, within a warehouse.

For now, their dream is to build a skateboard park where anyone can take a spin on a hoverboard - straight out of science fiction.