[ There's a pause as he considers this seriously for a moment. ]

Well, I'm not a quantum physicist. But say there isn't just one universe.

If there's more than one universe maybe they happen to exist next to each other. Maybe they even move. Things wear away from erosion, so maybe the holes are just part of the natural erosion of the worlds moving against each other. Eventually they move too much and then things fall into each other and they usually eventually wind up in the world where I'm from.