Can you create zero gravity on earth?

Answer 1

No, there is no known way to block the effect of gravity on earth. However, by going into freefall (or into a stable orbit, which is a way of having permanent freefall, constantly falling over the horizon), you fall at the same rate as everything around you; freefalling in, say, an airplane or elevator would have you falling at the same rate as objects in the airplane or elevator, the sides or walls, the ceiling and the floor. You would not register any weight on a scale, because the scale, too, would be falling; for most intents and purposes, relative to the object you are falling in, gravity would not affect you ... however, you are still falling, so you still have gravity.

An object in orbit simply has enough forward momentum that it falls at a rate that matches the curvature of earth. This is why the space shuttle goes what seems like ridiculous fast speeds on earth; to orbit, it must go tens of thousands of kilometers per hour. This puts it in constant freefall ... even in orbit, however, gravity still exists. Objects 'float' in the shuttle because the shuttle and everything in it are in freefall; if there were truly no or zero gravity, however, the shuttle would go in a straight line away from earth instead of orbiting the Earth.

Objects can be made to float in mid-air through other mechanisms, such as having enough lighter-than-air gas (such as hydrogen or helium) to compensate for the mass of materials in an object (such as in a balloon or airship), or magnets to suspend an object over a ground. However, because such objects are not in freefall, the effects of gravity are still felt within lighter-than-air vehicles or magnetically levitated trains or other objects; objects within them, when dropped, would still fall to the floor.