B Is a Universe Without Parallel Universes Possible in the Multiverse Theory?

[Colonel Travis]

Does any parallel universe theory include the concept that in at least one of the parallel universes, there is no option for there being parallel universes? If so, how could that unique universe not kill the entire theory?

 

[phinds]

Does any parallel universe theory include the concept that in at least one of the parallel universes, there is no option for there being parallel universes? If so, how could that unique universe not kill the entire theory?

Bertrand Russell solved that about 100 years ago with the old one about if the barber shaves everyone in town who doesn't shave himself, who shaves the barber?

I think he said something about how you just have to exclude self-contradictory elements from a set.

 

[Colonel Travis]

That's not solving it.

1.) I'm not a barber but I've cut my own hair for 20+ years. Maybe a particular barber cannot shave himself for some particular reason or reasons, but that does not mean that all barbers are incapable of shaving themselves simply for being a barber.

2.) Shaving is an act that does not define the actor's entire reason for existing. But if there is a parallel universe that exists where there are no parallel universes, how does this allow the existence of parallel universes in the first place? I'm not saying it doesn't, I'm just asking.

 

[berkeman]

That's not solving it.

Um, did you look up the Bertrand Russell piece that @phinds was referring to? It would probably make his response a lot more clear if you are not yet familiar with what he is referring to. A Google search should get you there...

 

[DaveC426913]

Does any parallel universe theory include the concept that in at least one of the parallel universes, there is no option for there being parallel universes? If so, how could that unique universe not kill the entire theory?

I suspect that there is no physics principle that can embody the idea of a "rule" in one parallel universe "disallowing" other universes through its own laws.

I suspect the only way is by conceiving of universes anthropomorphically, which is fallacious.

It would be like saying "I have a rule in my house that no other houses can be built within my line of sight."
Your "house rules" are simply not enforceable outside your house.

 

[Colonel Travis]

Um, did you look up the Bertrand Russell piece that @phinds was referring to? It would probably make his response a lot more clear if you are not yet familiar with what he is referring to. A Google search should get you there...

Yes, I'm familiar with the barber paradox. Like I said, it doesn't solve this question because that paradox is a limited, mathematical one. The barber does not have to be a man; the rule doesn't have to apply to other villages in the same world; it's not that it is literally inconceivable for anything other than the barber's paradox world to exist, etc. It was created in our imagination, which is also able to steer around it. I'm not saying we can disprove it. We can't. It is a real mathematical paradox in which there is no solution.

The difference is this: the barber's paradox is allowed to exist in this universe. It doesn't work the other way around. We don't need permission from the barber's paradox for our universe to exist. The barber's paradox does not deal with the fundamental laws of nature. It has rules, but those rules weren't put in place by themselves. The rules of this paradox only exist because we made them, which is a result of us being part of this universe following the certain set of laws that it does.

In contrast, a parallel universe that does not allow the existence of parallel universes would be governed by a different set of structural rules than the barber's village. How is this reconciled with someone who supports a theory of parallel universes that states we are ultimately part of a system that includes universes with all possible outcomes? Would the only way to support that be to also theorize that the laws of nature cannot be the same in all these universes?

 

[Happiness]

Take out those parallel universes that, in your terms, kill the theory?

 

[PeterDonis]

Does any parallel universe theory include the concept that in at least one of the parallel universes, there is no option for there being parallel universes?

Obviously not, since...

how could that unique universe not kill the entire theory?

...it would kill the entire theory, which is why no such theory exists.

 

[Colonel Travis]

Obviously not, since...
...it would kill the entire theory, which is why no such theory exists.

That would be my position starting out. But saying it would kill it does not explain why it would kill it. When I read a physicist defend the Many-Interacting Worlds theory by saying "all possibilities are therefore realized", what does that mean?
https://news.griffith.edu.au/2014/10/27/new-quantum-theory-is-out-of-this-parallel-world/
Why are other laws of physics not allowed in an entire system of universes where all possibilities exist?

 

[PeterDonis]

saying it would kill it does not explain why it would kill it

Isn't it obvious why?

When I read a physicist defend the Many-Interacting Worlds theory by saying "all possibilities are therefore realized", what does that mean?

It means that that's what you get if you assume that unitary evolution of the quantum wave function always applies exactly.

Why are other laws of physics not allowed in an entire system of universes where all possibilities exist?

"All possibilities" in the MWI doesn't mean what you are implicitly assuming it means here. "All possibilities" in the MWI already assumes a particular set of laws of physics; it doesn't leave open the possibility of other laws, only the "possibilities" contained in the quantum wave function.

 

[DaveC426913]

How is this reconciled with someone who supports a theory of parallel universes that states we are ultimately part of a system that includes universes with all possible outcomes?

Wasn't it Godel who wished to list the set of all elements that do not belong to a set?

Not very informative, about interesting nonetheless.

 

[DaveC426913]

Does any parallel universe theory include the concept that in at least one of the parallel universes, there is no option for there being parallel universes? If so, how could that unique universe not kill the entire theory?

How can an universe - that only exists because of a 'parallel universes' reality - rule out its own cause?

This would violate causality.
You're essentially allowing an effect to annihilate its cause.

 

[Colonel Travis]

"All possibilities" in the MWI doesn't mean what you are implicitly assuming it means here. "All possibilities" in the MWI already assumes a particular set of laws of physics; it doesn't leave open the possibility of other laws, only the "possibilities" contained in the quantum wave function.

Gotcha, thank you.