Where did the matter/stars etc from the universe expansion come from?
Are you asking what was before the Big Bang that created the known universe? In spite of what others might try to convince you of, the *only* answer to your question is that no one knows for sure. There are all kinds of concepts, ideas, notions, etc., but absolutely nothing science can point to and say, “Here’s how the universe began.” All we can do at this time is observe present conditions in the universe and try to work back from there, trying to get as close to the instant of creation as we can. At this time, the best guesstimate as to what happened at the first instant of the Big Bang is that: (1) space itself was created; (2) within that infinitesimal volume of space infinite energy existed; (3) a short time later, after the universe had expanded and cooled enough, the first elementary particles were generated by that existing energy. That’s just about it! How or why the Big Bang happened, if it did indeed happen, is the Big Question.
