According to the latest theories, our universe is like a bubble floating
in a large ocean with new bubbles forming all the time. Our universe emerged
from a cataclysm (the Big Bang), but it exits in an ocean of other universes.
In other words, Big bangs occur all the time creating parallel worlds to
ours. Also, possibly, our universe could become inhabitable and human beings
that would then have to move into another universe if they want to survive.