If the Big Bang created space time, what did the singularity of the Big Bang "rest" on?
Unknown. We have no reliable/testable theory as to anything prior to one Plank Time. There are theories, including that space-time was created at the singularity, that space-time has always existed, that there are multiple universes, take your pick. Since none of them are supported by any evidence, I personally am just agnostic about the whole thing.What did the mass that made the Big Bang rest on if their wasn't the fabric of space time?