Any particle unaffected by a force will continue along the straightest path. This is basic Newtonian physics. All particles are drawn toward each other however, and this Newton thought was a force. Einstein thought that particles are still traveling along the straightest path, but the universe is curved into something like a fourth dimensional sphere. To assist the understanding here, pretend the universe has only two dimensions and it exists on a piece of paper. We can only percieve of the paper, because only the surface of the paper is the right frequency of energy to be perceptible. the empty air over the paper is inperceptible for us paper people. when a particle moves along the paper, unknown to us the paper is a bit folded. The particles move over the fold and collide on a single point where the fold exits. As paper people we percieve that these particles moved to meet each other but they were really just moving straight forward, and our perception couldn't bend with the paper. that is the theory of relativity (specifically special relativity) that you're always hearing about. More interest, to me, though given less credence is the hypothesis that all existence is a single entity. One energy formerly composed of a single elemtary particle. Some unknown event or force (this is not the big bang) dividied the one into infintesimal elementary particles that make up the matter of the universe. All particles are drawn together because they are one. the implication of this is that all things, yourself and all that is around you was one entity until it broke apart and shuffled around in diferent forms, it's formation of electrons, atoms, cells, cellular structures, and then organisms leading to us (don't mention quarks, a quark is an elementary particle), compromised of the original energy as much as the table we sit at, all of it trying to become one again. This has nothing to do with consciousness, something that is naught but the creation of nerons and chemicals. If all were to be one again there would be no consciousness. It would be true oblivion, a destiny that may be possible nonillians of years from now.