Did you ever think about when the universe began? And what happened before that?

What was the universe like millions of billions of years ago? I mean, what happened before the universe (and like the egg shaped m from the big bags)? Anybody ever think about that? And scientist hav theories or something that you could talk about so a high schooler could understand? And fyi, this is a homework ignment im just curious. BTW i didnt know where to put it, so hopefully this is a good place.