# Parallel Universe

1. Apr 26, 2013

### Astro-Anouar

The Universe divide in two parts The observable Universe which is everything we can see (93 Billion ly) and the whole Universe which is Infinity !! so the question is : if the universe is infinity so if we had repetitions they will be in this Universe because the universe haven't edge ,No?! Second How can be possible a parallel Universe to Be into a Black Hole ?! and Finally , I Read that each Time you had to choose or Make a decision You Create a parallel Universe !! How that can be Possible ?! That mean When I have to choose One Number Between 1 and 0 and I choose 1 , a Big Bang happen somewhere and 13.7 Billion years pass and me when I write This Thread I Write 0 ?!!! is This Logic ?!

2. Apr 26, 2013

### phinds

Addressing just the first part of your question, it is not known that the universe is infinite. It MIGHT be, but no one knows.

The rest of your question has to do with the "many worlds interpretation" of quantum mechanics, which many of us consider nonsense, pretty much for the reasons you state.

Last edited: Apr 26, 2013
3. Apr 26, 2013

### Mordred

Gotta love pop media.

First off we don't know if the universe is infinite or finite. see FAQ sub forum.

yes the observable universe is only a portion of the total universe. The observable is finite.
that will also answer the edge question.

Parallel universes is at best a speculative possibility, there is no confirmed data supporting parallel universes. However the decision process in parallel universe theories usually involve alternate timelines with each decision. However that is only one alternate multiverse theory.

Thus far no evidence for any multiverse theory exists, they are derived mainly by supposition with mathematical model backing with little to no further substance.

edit: just noticed that Phinds replied his signature has a ballon analogy article you may want to read that as well.

4. Apr 26, 2013

### Astro-Anouar

Can You show me The Mathematical Model ?

5. Apr 26, 2013

### phinds

Well, it did back when we HAD signatures

it's at

www.phinds.com/balloonanalogy

6. Apr 26, 2013

### Mordred

7. Apr 26, 2013

### Boy@n

It's more probable that whole Universe is infinite than that it isn't. If it isn't then it has an edge. But en edge to what? What can be behind/beyond Universe? Nothing at all maybe? If so, can you define nothing? Is that which is not matter/energy nothing? What about quantum fluctuations, are they to be considered nothing? We cannot observe virtual particles, so, do they exist? Sure not, but are they nothing? Quantum fluctuation can be logically defined to be "nothingness", but the funny part is, they can become something. (I wrote a bit more about it here.)

You can also read a nice book on this topic (ebook too), titled: A Universe from Nothing: Why There Is Something Rather than Nothing by Lawrence M. Krauss (enter his name in YouTube.com and enjoy)

8. Apr 26, 2013

### Mordred

This has nothing to do with the many worlds interpretation however there are alternate multiverse models that do derive from Lawrence R Krauss everything from nothing scenario. Or rather other false vacuum derived models. This is due to the runaway inflation mechanism a key model example is bubble universes.

http://en.wikipedia.org/wiki/Eternal_inflation

Last edited: Apr 26, 2013
9. Apr 26, 2013

### Boy@n

If we remove everything from existence we are left with nothing, right? Now, if that nothing is not really nothing, but quantum fluctuations happening everywhere to infinity, then having many worlds or Universes is just "natural" ;)

Thanks for the link. (And previous ones too -- all saved for further reading.)

10. Apr 26, 2013

### Mordred

Your missing the point, the many worlds interpretation has to to with waveforms, probabilities and Schodingers darn cat. Here is a related thread.

the "bubble universe" is derived in the manner you described, in eternal inflation and chaotic eternal inflation. the premise of the development of the multiverses are significantly different.

Its important to keep them seperate for as the premise behind the two multiverse models are different

11. Apr 26, 2013

### Mordred

this is more what your describing see attached although the quantum particles created via expansion ha nothin to do with Casimir effect. Its more accurately described by Parker radiation and false vacuum, which can be considered a form of Parker radiation. Or in other inflation models the inflaton field

#### Attached Files:

• ###### Where-Did-It-All-Come-From.pdf
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12. Apr 26, 2013

### Boy@n

I didn't even try to compare the two models till now. But in the end, don't you end in the same repetitions of everything to infinity, no matter of the model used? (And I agree, the process is surely different, but the end result isn't. Everything possible happens, in both models.)

Let's say I am thinking what to write right now, either it is exactly what I am writting or something else, it doesn't matter, within infinity all possibilities shall happen, independent of the model you use to desribe our Universe/reality, right?

P.S. I appreciate your feedback, even if you might not mine ;)

13. Apr 26, 2013

### Boy@n

14. Apr 26, 2013

### Mordred

Assuming VERY loosely that both scenarios do in fact create a multiverse scenario. Then both can lead to multiverses in their own manner. However the reasons and underlying mathematics is considerably different as such the importants of how you refer to them is vital. So the treatment of each is also different particularly when trying to hypothesize a particular property of said multiverse.

Keep in mind multiverse theories are just that lol. Its all theoretical and not part of standard cosmology which describes only the observable universe.

You might want to look at the link on Bubble universes and rethink your article that you postd in QM forum.

and I enjoy any and all feedback thats how we all learn lol so no worries

also keep in mind the many worlds interpretation is misrepresented as a multiverse scenario by pop media.
Its more a visualization tool that states in the example of the darn cat that in QM until examined the cat is both dead and alive. Hence until examined both answers are correct

Last edited: Apr 26, 2013
15. Apr 26, 2013

### Boy@n

Sure, I'll read as much as I manage ;)

As for this test/scenario, I'd rather say, we just don't know, until we check ;)

16. Apr 26, 2013

### Mordred

QM focusses on accurately describing all possible probabilities. The many worlds interpretation is a descriptive of that.

17. Apr 26, 2013

### phinds

Nonsense. If it is finite, it will surely be unbounded (no edge).

18. Apr 26, 2013

### Boy@n

(to be deleted)

Last edited: Apr 26, 2013
19. Apr 26, 2013

### phinds

When you say "a finite universe has to be infinite" I assume that's a typo and you mean "a finite universe has to be ... WHAT ???" Bounded? Unbounded? Clearly something that is finite doesn't have to be infinite, although unbounded DOES mean infinite in one or more directions, because you keep passing your starting point, like going around and around the earth.

The problem with a bounded universe is that it would have an edge and there doesn't seem to be any way physics as we know it can handle an edge. It just wouldn't make any sense.

20. Apr 26, 2013

### Boy@n

Yes, a typo, sorry. I meant to say: "Universe (whole of it, not just the observable "part") has to be infinite."

Observable Universe is finite though, and with an edge, or else we couldn't meassure its length, right?

Last edited: Apr 26, 2013
21. Apr 26, 2013

### phinds

The observable universe is a sphere of about 50 billion light years radius centered on your left eyeball. It has no edge except in the sense that ANY sphere that is defined as being centered on your left eyeball and extending for n units of length has an "edge". Better to say it has a defined radius, or in the case of the OU, a measured radius. This is NOT the same as an edge.

22. Apr 27, 2013

### Astro-Anouar

I didn't Understand what you mean, Something finite must have an edge a limit this is the sense of finite , No ?

23. Apr 27, 2013

### phinds

No, absolutely not. Think of the surface of a sphere. JUST the surface. That is a 2D construct that is finite but unbounded.

We don't know the shape of the universe but it is believed to be either infinite or finite and unbounded --- unbounded in 3D in the same way that the surface of a sphere is unbounded in 2D.

Last edited: Apr 27, 2013
24. Apr 27, 2013

### WannabeNewton

The 3-sphere spatial sections are of course compact but they have empty manifold boundary, as phinds noted. Don't confuse compactness with non-empty manifold boundary. You are picturing $S^{2}$ in $\mathbb{R}^{3}$ and noting how it is bounded in the sense that it can be contained in an open ball but this is not equivalent to having a non-empty manifold boundary. If $S^{n}$ had a non-empty manifold boundary then it would have charts which mapped to open subsets of the upper half plane but all charts on $S^{n}$ map to open subsets of $\mathbb{R}^{n}$.

25. Apr 28, 2013

### Boy@n

A circle too has no edge ('2D ant' walking on it can go on and on eternally) and thus can be considered to be infinite (even though I'd say a circle has finite number of points, each being a Planck length).

No matter how we see the circle or a sphere, both are a finite objects, and in this sense observable Universe is finite too, right?

I can see that observable Universe has no clear edge, but all of its mass is finite, true? And if mass is finite then that is what defines the 'object' (or let's say space-time curvatures with mass in them), so, observable Universe if a finite 'object' within infinite space-time.

Last edited: Apr 28, 2013