What If Our Universe Collides With Another?
“In current mainstream models, where dark energy and inflation are strapped on like a sort of prosthetic, there is just one Universe, and being alone, it can’t collide with anything. But in models derived from string theory, dark energy and inflation turn up naturally, which is nice. The catch is that, in these models, our Universe might not be alone.
We don’t know how many bubbles of inflationary universes might have seeded in some sort of over-arching background called a “false vacuum.” This is a part of a larger string theory problem: it is so generic that the number of universes and the values of fundamental constants in those universes are largely unconstrained. One way to narrow the field is to look for evidence of these other bubbles. This is exactly what a group of researchers has done.
WAAAAAIT, I hear you cry. Surely, by definition, we cannot see other universes. You would be correct. But in a Multiverse that is crammed with bubble universes, they may sometimes collide. When they do so, they will stretch space-time at the location of the collisions.”