I am a novice and dabbler, but very interested in the evolving understanding of the laws of nature. Most recently, I was listening to a discussion about the surprising discovery (granted, not a new discovery) that the universe is expanding at an increasing rate rather than at a decreasing rate. Here's my understanding of the now-outdated theory: The expansion of matter must be decreasing because of gravity. Just as a ball, when thrown straight up, slows and then begins to fall, so must the matter in the universe be slowing as it distances itself from other matter. My question: Obviously, the ball in the above scenario slows then accelerates back toward the ground because of the Earth's gravity. Since we do not know what the matter is expanding toward, has it been determined that there is not a force, possibly even gravity itself, acting on the matter and pulling it outward (for lack of a better word) away from the matter we previously thought would be pulling it back in? I hope I have described my question clearly. If not, please feel free to ignore, mock, or deride me as you see fit!