How Does Multiverse Theory Make *Every* Universe Possible?

[Gaz]

infinite is used far to much in science. I can see that there could be other universes it makes sense we once thought there was one planet then one solar system and so on so one day someone might find other universes but to say there is other Me's out there doing everything I do up until a decision I make and Alternate me makes is so far fetched It is almost impossible. For starters just measuring water boiling isn't possible it is so random imagine the odds odds of two identical big bangs.But other universes with planets and stars all made of anti matter and things like that are cool to imagine out there. As for not being able to see them . We don't know what our universe is expanding into mabye light cannot travel through or mabye it will get here one day.

 

[craigi]

To avoid getting bogged down in whether or not multiverse theories are testable from a philosophical viewpoint or if the universe can be infinite, first be sure that you understand the distinction between the observable universe and the global universe in cosmology.

https://en.wikipedia.org/wiki/Shape_of_the_universe

 

[NIgelSmith50]

On the evidence of this debate, it seems that there is indeed an abandonment of the scientific method with regard to multiverse theory.

Not only do supporters of the hypothesis fail to offer any real science, but they seem to revel in the non-argument of proving a negative. I therefore have no alternative but to dismiss it on the same grounds that I would dismiss a religious belief.

This topic should be moved to philosophy or religion since it is clearly not science.

 

[craigi]

On the evidence of this debate, it seems that there is indeed an abandonment of the scientific method with regard to multiverse theory.

Not only do supporters of the hypothesis fail to offer any real science, but they seem to revel in the non-argument of proving a negative. I therefore have no alternative but to dismiss it on the same grounds that I would dismiss a religious belief.

This topic should be moved to philosophy or religion since it is clearly not science.

This is a very common misconception.

Multiverses are predictions of other theories, not postulates. Some of these theories are widley accepted, others remain controversial. To understand why, you'll need to understand some Inflationary Cosmology and the Relative State Formulation of Quantum Mechanics. To discuss them, I'd suggest that you start a thread in the Cosmology or Quantum Physics subforum respectively. But be warned discussions on the Interpretations of Quantum Mechanics become very heated there, usually resulting in someone getting upset and the thread getting closed.

If you want a fuller understanding of the subject then I'd recommend Tegmark's recently published book, Our Mathematical Universe.

 

[Enclose]

This topic seems to have gone a bit off track from the original question. The question is in the metaphysics domain, which I like to ponder about so I'll try to give it a shot.

Is every combination possible based off of uncertainty? When the big bang happens in another universe and one electron moves slightly differently because of uncertainty it changes everything. Is that why there are "infinite" number of universes?

When people say infinite do they really mean infinite? So is it actually true (if I were in another universe) that everything could be the exact same, but instead I'd be writing the answer to this question just because I figured it out before anyone else on the world or does that have implications that would make the multiverse different in different ways?

First of, I'll restrict my definition of multiverse to a (possibly infinite) number of universes operating under the same physical laws. So gravity, all forces and constants would be the same. Another assumption is that behaviour at the quantum level is truly random (adhering to the law of probabilities), and not a result of our ignorance of the true underlying principles.
In such a multiverse it is possible for every single plausible (meaning, not breaking any laws of physics) outcome to be realized. Most universes would have evolved so differently that Earth would never have formed in them. Others (a vast minority, since it is enormously improbable) would have evolved almost identical to ours with only 'slight' differences. You could be an MMA fighter or a doctor in one of those. But is it the real you then though? It means you chose another path in life, which implies you're wired differently or shaped by different experiences in this universe, so it would not really be you. Plus your path and experiences in life would be completely different than in this universe.
Every different action, however small it may be, will make the future of that similar universe diverge more and more from that of this one. It all boils down to chaos theory really. The state of each universe is extremely sensitive to the initial conditions (big bang), the closer the initial conditions of a universe are to that of ours, the more it will resemble ours. But the further you go in time, the more tiny differences accumulate and the more each universe diverges from the other.

So, to answer your question more direct, yes, every combination based of uncertainty is possible and the outcomes are, for all intends and purposes, infinite. This is ofcourse all just hypothetical :)

 

[ChrisVer]

I don't think that the idea of multiverse wants the laws of physics to remain the same. I think that different string vacua would result in different parameters (?) and so different laws.

 

[Enclose]

I don't think that the idea of multiverse wants the laws of physics to remain the same. I think that different string vacua would result in different parameters (?) and so different laws.

I excluded universes with different parameters because the main argument would still be the same. The only difference is that the number of universes similar to ours would be vastly smaller in comparison to the whole plethora of universes in the multiverse.
Also admittedly I know very little about string theory so I don't know what restrictions it might pose on a multiverse or the laws of its individual universes.

 

[craigi]

I don't think that the idea of multiverse wants the laws of physics to remain the same. I think that different string vacua would result in different parameters (?) and so different laws.

Some types of multiverse have exactly the same physical laws as our universe, others do not. Examples of those that do are those specifying the region of spacetime beyond our cosomlogical horizon and by the MWI.

 

[julian]

Not just string theory where you get universes with different parameters: "Discrete quantum gravity: a mechanism for selecting the value of fundamental constants" http://fr.arxiv.org/abs/gr-qc/0306095 - given this is a minimal combination of GR and QM it might be more general?

"Smolin has put forward the proposal that the universe fine tunes the values of its physical constants through a Darwinian selection process. Every time a black hole forms, a new universe is developed inside it that has different values for its physical constants from the ones in its progenitor. The most likely universe is the one which maximizes the number of black holes. Here we present a concrete quantum gravity calculation based on a recently proposed consistent discretization of the Einstein equations that shows that fundamental physical constants change in a random fashion when tunneling through a singularity."

Still you have to give way to the fact that universes like ours fall in a narrow set of parameters.

 

[NIgelSmith50]

This is a very common misconception.

Multiverses are predictions of other theories, not postulates. Some of these theories are widley accepted, others remain controversial. To understand why, you'll need to understand some Inflationary Cosmology and the Relative State Formulation of Quantum Mechanics. To discuss them, I'd suggest that you start a thread in the Cosmology or Quantum Physics subforum respectively. But be warned discussions on the Interpretations of Quantum Mechanics become very heated there, usually resulting in someone getting upset and the thread getting closed.

If you want a fuller understanding of the subject then I'd recommend Tegmark's recently published book, Our Mathematical Universe.

Your opening two sentences are a clear contradiction.

If the theories are controversial, as you acknowledge, it is not a great basis for multiverse theory. Postulates would be a more applicable term based on your own logic.

 

[craigi]

Your opening two sentences are a clear contradiction.

If the theories are controversial, as you acknowledge, it is not a great basis for multiverse theory. Postulates would be a more applicable term based on your own logic.

You'll have to explain where you see the contradiction, because I can't see how you're reading what I wrote.

If you're not sure how a multiverse is predicted by Inflationary Cosmology, String Theory and the Relative State Formulation of Quantum Mechanics, then I recommend that you start there, rather than getting bogged down with semantics. It'll all become much clearer, instead of getting confused about which are theories, which are postulates and which are predictions.

 

[ChrisVer]

Do you have any source explaining the MV in Inflationary Cosmology?
Because the other sources have not satisfied me... strings is maths (so no real connection to nature and the universe, leave aside the prediction of more)...if we find SUSY I might become less of a skeptic (without leaving my skepticism until the end)... and Everret's idea is just an interpretation of QM and not a theory which can make measureable predictions (it's more like a philosophy, in a worse "position" than strings)

 

[craigi]

Do you have any source explaining the MV in Inflationary Cosmology?
Because the other sources have not satisfied me... strings is maths (so no real connection to nature and the universe, leave aside the prediction of more)...if we find SUSY I might become less of a skeptic (without leaving my skepticism until the end)... and Everret's idea is just an interpretation of QM and not a theory which can make measureable predictions (it's more like a philosophy, in a worse "position" than strings)

Sure. Start off with Tegmark's recent book 'Our Mathematical Universe'. It deals with the multiverse in all forms of which we are aware of to date. From there you should be looking toward the work of Guth and Linde for more detail from an Inflationary Cosmology perspective.

Regarding predictions of Everettian QM, you should look for work by Deutsch. Unfortunately, this is behind an internet paywall, so you may need to find an alternate source, if you don't want to pay and don't have access to an academic library.