I was watching this video: https://www.youtube.com/watch?v=KcXxHZssCh4 At 17:36 Michio Kaku says "There is no such thing as gravitational pull. Space is pushing me into this chair." So, is it the size of the object in space that determines the gravity or the mass? A neutron star has a small size and contains a large mass and it's gravity is enormous, Jupiter on the other hand has a small mass but a large size. I'm trying to picture the curvature that causes gravity. I picture earth sitting on top of a sheet and I see the curvature but, in space there is no up, down, left or right so the curvature would completely surround the earth. What I don't understand is how could mass cause more curvature and in turn more gravity?