Could our universe be a small part of a bigger universe?

[We put this question to Carolin Crawford as part of the Planets and Cosmology show]

Carolin Crawford: Anything is possible. It's unlikely to be a star as we know it, as stars don't form until thousands of years after the big bang. There's always an idea that our Universe is just part of another Universe. This is really a philosophical question, as it's one that we cannot answer at the moment...