I`ve read that the universes expansion is accelerating. To explain this we have introduced concept of Dark matter and energy. However, Hubble's law: v = H*d means that a speed that separates two points is proportional to their distance. But since they are moving apart the distance becomes greater and so the speed must become greater. I think this means the speed of expansion is increasing. So the expansion of the universe is accelerating. I`m sure I`ve got something wrong here, is the acceleration we explain with Dark energy a "surplus"? Hope I made myself clear.