The no-boundary wave function also states that space-time was not what we see today at the outset of universal expansion. “When the universe started out,” Hartle explains, “there wasn’t ordinary space-time. Instead of three space directions, as we have now, there were four space directions. At some point, a transition was made to ordinary space-time.”

Four dimensions of space, just before time began. I could live with that. It look as a universe where there is no change, because time can be understood only as a measure of change. But if there was no change, how come that something happened that brought about this universe?

Moral: The model is probably much more complex than what is described here...

Have you heard the TED speech that was clipped earlier that talked about string theory? It actually suggests that we live in 10+ dimensions of space, but we can only see three. It suggests the other dimensions are so small we can't see them. It's an interesting theory. I love this stuff myself.

Thanks for the reference, and yes I am familiar with the materials presented in that talk. String theory cosmology is really esoteric to the uninitiated like us.

Maybe it bounced because there is a critical mass, or a limited mass that can accumulate at one point.
Black holes may be big enough to cause a singularity, with it's mass, but there is every reason to think that different conditions exist on a universal scale. what we know of black holes is through calculation, but also by what we see being drawn into them. Stephen Hawking theorized 'Naked Singularities' Black Holes that had no input. Whether they can exist. Perhaps the last collapse had enough weight and drawing on absolutely empty space, the Universe turned passed a threshold an 'turned it self inside out'
perhaps we'll find an echo.