There are stars with enough mass to collapse on themselves, forming what have been theorized as black holes. It is thought that within these black holes there is a point called "singularity". It has been thought that beyond singularity are tunnels, or ‘shortcuts’ that can lead to another or other universes. It is said that at the point of singularity, it was agreed that it was impossible to know physical behaviour. This could possibly mean that there is a whole new set of Physic Laws.
With that, our universe is defined as the observable that involves the galaxies, stars, planets, and life that we know. This said there could also be a possibility of change that there could be a loss of basic forces such as: gravity, electromagnetism, and the strong and weak nuclear forces. So, if this were to possibly happen, (that the force/s did not exist or was changed) what we would know about our universe would not even exist.
According to Sir Martin Rees, "If nuclear forces were slightly weaker, no chemical elements other than hydrogen would be stable and there would be no nuclear energy to power stars. But, if the nuclear forces were slightly stronger than they actually are relative to electric forces, two protons could stick together so readily that ordinary hydrogen would not exist, and stars would evolve quite differently."
The Multiverse theory has been an accepted theory that describes the continuous forms of universes through the collapse of giant stars and the formation of black holes. With each of these black holes there is a new point of singularity and a new possible universe?
If there are parallel universes, then the ‘Bubble Universes’ should exist as such.
The ‘Bubble Universe’ is a where there are layers of universes, from universes 1-6, with then our universe on top and that, in every disk; they have physical constants that are different from our universe- our universe is just one of the bubbles...
Yet even though it is just a theory, it’s an amazing thought to know that there are other universe and (possibly) life forms out there.