“The mind, once expanded to the dimensions of larger ideas, never returns to its original size.” -Oliver Wendell Holmes But it isn't just your mind that expands as time goes on and you increase your knowledge, but the entire Universe as well. General Relativity, as it turns out, doesn't leave us with much of a choice. If you start with a Universe full of matter and radiation, it's got to expand, otherwise it will collapse in on itself!