The reason why we have gravity. I think it is because of the insulation we have between us and the center of the Earth. The earth beneath us separates space itself. Space wants to go back to that center point in the Earth, however it can't because the elements in the ground are in the way. So, space is always pushing down on us and everything on the surface of Earth, trying to go to that center point. Now, let's think in terms of density. For instance, what if the Earth was made of aluminum. Aluminum is not a dense material, so it does not insulate space from the center point very well. It has too much empty spaces in it's molecules for space itself to occupy. Therefore we would weigh much less on the surface of an aluminum planet. Space can not push back very hard with there being too much space between us and the center point. Now, if the Earth was made of a much denser material, like gold, as a good example. Gold would be a very good insulation against space. There is much less space between the molecules than aluminum. On a planet of solid gold the same size of as our Earth, we would weigh an incredible amount. Space would be pushing us toward the center point extremely hard. So, thankfully, we have just the right density of materials, and just enough space under us that gives us a tolerable push toward the center point from the space around us. Space appears to be a form of energy. Or it could be that the earth under us simply compresses space like a spring, and it pushes back on us. I know that this is not the conventional answer, but conventional science only states that gravity exists, yet gives no suitable explaination for it.