Multiverse vs. Parallel Universe

[weeman]

Over the last couple years it seems that the theory of a multiverse is gaining more public notoriety. I personally am I big supporter for the idea of an infinite system of universes. However I've been slightly confused by one thing:

I've heard some say that a multiverse system is a higher-dimensional membrane that spawns universes in addition to our own. Each universe may be completely different; governing its own laws of physics, space and time. I've even heard that universes may not have space and time, they have something else.

Now, I've also heard that multiverse theory is the idea of parallel universes coexisting with our own. They are universes that are off-shoots of our own. In other words, they are similar to our universe but with different outcomes. Eventually, every conceivable probabilistic possibility will actually happen in an infinite system of parallel worlds.

So, my confusion is this: Are there two sides to the same multiverse theory? Is it true that one side says that a multiverse is a system of universes having nothing to with each other while the other side says that a multiverse is an infinite system of parallel universes to our own?

 

[SpeedFreek]

It's a little deeper than being two sides of the same story, it is more like looking at different levels of abstraction, where each level includes the concepts from the level before it!

First we have the plain old "what is beyond our observable universe", where the laws of physics remain the same, but there may be differences in the content - we might have areas where the average density is enough to cause collapse rather than expansion, etc. In theory, with an infinite universe, there should therefore be places exactly the same as this place, which can be thought of as a parallel universe.

Then there is the bubble universe idea , where different regions are separate "bubbles" and each region can have different physical laws. Perhaps our universe as described in the above paragraph is contained in one of those "bubbles". Perhaps there is an infinity of these bubbles.

Then we have the many worlds interpretation of quantum physics, where the possibilities for the outcome of events "creates" a universe where each possibility occurs. But all these "many worlds" all share the same laws of physics, so perhaps they can all fit into the plain old infinite universe. In that infinite universe, you would have an infinite number of doppelgangers...

Lastly there is the whole shebang, the theory of everything, everywhere, which encompasses all of the above.

 

[yevaud]

So, my confusion is this: Are there two sides to the same multiverse theory? Is it true that one side says that a multiverse is a system of universes having nothing to with each other while the other side says that a multiverse is an infinite system of parallel universes to our own?

Well, if you buy into everything ever postulated, then both. As to the former it's said that separate universes are likely present, and are forming all of the time, as a natural aspect of the dynamics of the Multiverse. The latter refers to Kerr's "Many Worlds" theory, in which each quantum decision creates or even requires a parallel universe, and the only difference between the two is that different quantum outcomes occur in each.

I just plain don't know, myself...

 

[weeman]

Thank you for the insight. I've been reading a lot on current theories. I find the theory like that of Kerr's to be the most interesting.

I've heard that one of the earliest examples of these quantum decisions was early in the universe when massive amounts of matter and antimatter annihilations were taking place. In our universe, matter mostly won the battle, however in a parallel universe antimatter won, and therefore dominates our universe.