Every experiment that’s ever been done (on this subject) verifies the conservation of mass and energy. As we learn, many of the theories will be ruled out, but we’ll probably never be for sure sure. Over any time scale there is always a little energy error, but the larger the time scale the smaller the energy error. But maybe, just maybe, the unimaginable amount of matter in the universe is some kind of amazing quantum clerical error. Bubbles: It could be that our universe “bubbled” off of an even larger universe, that had plenty of mass and energy to spare.