Will the Universe Keep Drifting Apart?

For a long time we knew that the universe was expanding. We didn't really understand what had caused it to expand. Is there enough mass in the universe to slow that expansion down eventually to zero and maybe bring it back to a big crunch? That was sort of the big question around the mid 90s. So spoiler alert for those of you who haven't gotten to read them yet, people developed a new way to measure distances using type 1a supernova.