I've always been interested in Physics so have finally decided to do a Physics degree. I've been reading various things to help prepare myself and have just been reading about the laws of thermodynamics and mass-energy equivalence. As I'm reading through different articles about these subjects I've been surprised at the lack of mention about how this relates to the total mass-energy in the universe. It's my understanding that everything that exists, right down to the atoms in our bones came from the energy that was released in the big bang. Over time as the universe cooled, some of this energy became sub atomic particles, then atoms were born. So essentially through mass-energy conversion the energy that existed back then exists in everything around us. So, for example, following this keyboard back through time would show that every part of it was in existence back then but obviously in different form. Am I understanding this right? Most of what I've been reading seems to relate to things on a much smaller scale so I'm not sure if I'm misinterpreting things or if what I'm thinking about relates to a completely different theory. It's probably a silly question but I'm still learning.