that lower force of gravity onthe moon means you can jump much higher there than on the Earth.OK, Greg, this sounds great,but I actually want to see this.So, show me the science!You've got it ...

Lots of people, including Einstein (see above), talk about gravity, the restraining force which makes people walk on floors instead of floating in midair. What worries Roger Babson, 74 ...

DICK:There you are, gravity. SIR ISAAC NEWTON:Aaahh. DOM:'Newton was born in 1643, when the laws of nature and the universe were a big mystery. It was the early days of modern science.' ...

But for those with physical and learning difficulties they can also offer a gravity-free way to exercise ... from green to purple and music plays as children bounce up and down.