Assuming the following
A universe is the surface from a bubble in hyperspace. Inside a bubble there is nothing, only the surface represents a universe. The size of the bubble is time.
Dark matter is from bubbles different then our own bubble that only shares gravity.
The big bang are bubbles colliding, creating a other bubble.
My problem is if bubbles do only share gravity why would they have a collision, I expect that they would just pass trough each other without creating a big bang?