: If you place two particles of the same mass next to each other, their gravitational force will cancel each other out yeilding zero attractive force.

Err, you're saying that 1+1=0 and that 1+2=1

What you are saying is that there is an equal number of anti-gravity particles to gravity particles. Should be easy to isolate an anti-gravity particle, place it next to another and watch them repel each other in accordance to the laws of Gravity. Woops, never see that in physics labs around the world.

Moreover, some thing the mass of the Earth would have no Gravitational attraction if it had an even number of particles - they all cancel. If it had an odd number the gravitational atttraction felt would then be from the one particle not cancelled out. The same is true for any body ergo all objects have the same gravitational force being 0 or 1.

Mass is additive with respects to gravity. More mass = more gravity. The Universe has no respect for your beliefs and behaves the way it wants to.

Yelmalio - Seeker of truth.