I'm not sure how to think about probability when it's applied to something like statistical mechanics. My thinking might be off since I haven't taken a formal thermodynamics class yet. I guess the example I will use is a room filled with two gases. The gases will disperse randomly. The probability of the gases randomly separating to different parts of the room is very small. I read before that you would have to wait until the end of the universe essentially for this to happen. Does that mean it will happen? Will the system the probability describes breakdown before that happens? I guess I'm asking if there is a non-zero probability does that mean it must happen somewhere or is it just that it is possibility and there has to be a sufficient amount of time for it to be seen? Sorry if this is a naive question.