Mark, a recent programme I saw suggested that some current theories liken our universe to a slice of bread in a big loaf. We are limited to perceiving the whole loaf or other slices, by our inability to speculate beyond about 7 dimensions, although some, somehow, have speculated that there may be up to 11 dimensions.

The speculation was that big bangs occur, whenever these slices in the loaf bump up against each other.

I think when the next one happens we will be toast, if not before.