“Modern cosmology theory holds that our universe may be just one in a vast collection of universes known as the multiverse. MIT physicist Alan Guth has suggested that new universes (known as “pocket universes”) are constantly being created, but they cannot be seen from our universe.
In this view, “nature gets a lot of tries — the universe is an experiment that’s repeated over and over again, each time with slightly different physical laws, or even vastly different physical laws,” says Jaffe.
Some of these universes would collapse instants after forming; in others, the forces between particles would be so weak they could not give rise to atoms or molecules. However, if conditions were suitable, matter would coalesce into galaxies and planets, and if the right elements were present in those worlds, intelligent life could evolve.”
Hope this answers your question. Well it’s not an answer, just a theory, like a lot of things in science! 😉
I always used to wonder this, and despite all my reading on the subject, I’ve never really read an answer I’ve been totally satisfied with. This is largely because we just don’t know, and in fact, if you try to use the kind of physics that describes our own part of the galaxy pretty well, it’s likely it won’t work for the outer rim of ‘space’, because physics has a habit of breaking down in other parts of interstellar space.