I've managed to grasp general theory of relativity pretty well but I'm stumped on special theory. I understand nothing can travel at the speed of light, and that the speed of light is always constant. So the closer you get to catching the speed of light, it still looks like it's beating you by 671 million miles an hour. But why does time slow down for you, the closer you get to this speed? I just don't see the connection. Your clock is slowing down too, just like lights clock. I get that you can't go the speed of light, and light will always speed off from you at the speed of light, but why does your clock slow down? What does that have to do with anything? thanks!