I had read a response in a pretty old post in the cosmology forum stating that anti-gravitron's can't exist. I was hoping to follow up on that here in this new thread. Can someone explain that in more detail? It's always struck me as odd that the other 3 fundamental forces, Electromagnetic, Strong Nuclear and Weak Nuclear, come in positive and negative pairings and it seems like the statement "and Gravity is always attractive" is simply tacked on for convience. So my personal, amateur theory goes: Half of the universe is composed in Repulsive Material By that I mean, what if: As the universe cooled, gravity decoupled from the the other 3 forces types in attractive and repulsive forms. The half that causes "attractive gravity" binds with the materials of the universe forming attractive matter that naturally collects together. The fundamental repulsive "matter", "energy", "quanta", whatever, naturally seperates from itself and all other matter in the universe. Slowly, areas of high matter density collect to form stars, solar systems, galaxys, etc. The repulsive matter spreads out amongst the least dense areas of the universe. In my view, this: 1) Would cause the accelerating universe, as all that distributed repulsive material pushes against everything else in the universe. 2) Would explain the change in acceleration of the universe. At first, the attractive and replusive material would be highly disordered. As the attractive matter and repulsive got organized over time, the forces would align better increasing the acceleration of the universe. 3) Would create 50% more matter in the universe, helping to explain much of the missing matter in current observations.