Edit: This is a good question, one I probably don't have a high enough level of understanding of physics to answer, but here goes.. in my last answer I forgot about about Einstein, so Newton says the centre of gravities attract, Einstein says mass curves the space surrounding it which effectively makes you 'fall' into the curve. Roughly speaking. As general relativity was a modification to Newtonian physics I'd say Einstein is on the ball here. I think Newtonian physics might be very rudimentary in its explanation of gravitation. Einstein says we'd stick to the walls.