I understand that every chemical reaction has a mass defect - albeit it is very, very, very, very small, to the point we simply assume Law of Conservation of Mass. Nuclear reactions have a more sizable mass defect, hence the very high amounts of energy released. However, suppose some astronomically high time. It is possible that all of the matter in the universe could be converted to energy somewhere incredibly distant in the future? Are there any ways in which new matter is introduced into the universe, and would that amount be greater than the amount lost by general physical phenomenon? We've only briefly touched on this concept in my chemistry class but since we have to move on our teacher doesn't have much time for much theory questions. I'm very curious but my knowledge doesn't extend very far.