The apple fell from the tree to the ground because of atmospheric pressure rather than gravity?

Good discussion topic, I don't know exactly but there are evidence piling up that space has a definite discrete value for mass. Don't exactly hold me to it, and it requires some research.
What I do know is that gravity's range is unlimited, thus it is everywhere because it acts between and among all different masses spread out in space.

The stuff that we know as mass (stars, planets, moons, asteroids, space dust) is equal to 4% of the universe. You could remove all that stuff (and with it, gravity) and not affect the shape or movement of the universe a bit.

Joe(okay, maybe a bit, but not much)Nation