The greatest science teacher to grace the halls of Heritage High School, and one of the greatest influences on my scientific knowledge, once explained this to his class when studying the universe.
It went something like this:
Gravity can be explained easily by using a favourite childhood toy, the trampoline. For simplicity, the universe is a flat surface. The mat of the trampoline will substitute a given area of the cosmos. From experience one should know when an object is on a trampoline the mat flexes downward making an imprint on the surface of the trampoline, this is its gravitational field. Now place an object, say a baseball, into the depression of the larger object, say a bowling ball, and spin it around the central object, for this hypothetical situation friction is not a factor. In practice the smaller object will fall into the larger object but in space, where there is not an overriding gravity towards the earth and friction is in absence, the object will stay in the gravitational field of the larger object as long as it keeps a steady speed around said object and no object or force acts upon the object. The smaller object also displaces area on surface of the mat and a smaller object, a marble, can be placed within the dip. This object is like a moon to the earth with the largest object being he sun. This motion will continue until an outside force interferes with the balance; for example: increase the speed of the moon and it will start to climb out of the gravity field of the earth and the same for the earth to the sun.
This can be enhanced by placing more objects like the baseball into the orbit of the bowling ball, inside or outside the orbit of the first baseball, as long as they are within the field of the bowling ball. Marbles can be placed around the baseballs as before and a working model of our solar system can be made using a trampoline, a bowling ball, eight baseballs, and dozens of marbles.
Gravity is the displacement of the cosmic fabric that all things rest on. The greater the mass of an object the greater the displacement or gravity of the said object. The stretching and skewing of hyper-dimensional fabric gives us the illusion of a three-dimensional world but we all feel the pull of spheres close and afar.
Disclaimer: this experiment will not work within normal conditions due to earth gravity pulling the objects towards the ground and the friction of the mat slowing the objects to a rest.
