What types of parallel universe do you find most plausible?

[pulstar]

1) Quilted multiverse conditions in an infinite universe necessarily repeat across space, yielding parallel worlds.
2) Inflationary multiverse says that eternal cosmological inflation yields an enormous network of bubble universes, of which our universe would be one.
3) Brane multiverse states that in M-theory, in the brane world scenario, our universe exists on one three-dimensional brane, which floats in a higher dimensional expanse potentially populated by other branes – other parallel universes.
4) Cyclic multiverse is saying that collisions between braneworlds can manifest as big bang-like beginnings, yielding universes that are parallel in time.
5) Landscape multiverse states that by combining inflationary cosmology and string theory, the many different shapes for string theory's extra dimensions give rise to many different bubble universes.
6) Quantum multiverse creates a new universe when a diversion in events occurs, as in the many-worlds interpretation of quantum mechanics.
7) Holographic multiverse is derived from the theory that the surface area of a space can simulate the volume of the region.
8) Simulated multiverse implies that technological leaps suggest that the universe is just a simulation.
9) Ultimate multiverse is the ultimate theory, saying the principle of fecundity asserts that every possible universe is a real universe, thereby obviating the question of why one possibility – ours – is special. These universes instantiate all possible mathematical equations.


For me its options 7 & 8.

In case you're clueless about any of this or not interested in this topic please skip this thread.

[Red Pill]

It's a fascinating subject, thanks for bringing it out Pulstar. I think at the current stage of physics nr 2 seems the most likely, but new hypothesis come out all the time. Unfortunately they all seem difficult to prove. I always found particularly interesting the quantum multiverse (Everett many-worlds interpretation of Q. Phys) but I have a hard time believing in it, it feels counter-intuitive, but that doesn't mean anything. Nr 9 is Max Tegmark Level IV (https://space.mit.edu/home/tegmark/multiverse.pdf). There is also a philosophical theory called Modal Realism that states that everything that can possibly exist does exist. Nr 9 seems close to it, but I don't know if everything that can LOGICALLY exist equates to everything that can MATHEMATICALLY exist.

[Hamilcar]

tbh they are all plausible and the simulated universe theory doesn't necessarily contradicts all the other possibilities

[Tauromachos]

The binary parallel universe called Virtual Reality

I'm in there everyday

[pulstar]

It's a fascinating subject, thanks for bringing it out Pulstar. I think at the current stage of physics nr 2 seems the most likely, but new hypothesis come out all the time. Unfortunately they all seem difficult to prove. I always found particularly interesting the quantum multiverse (Everett many-worlds interpretation of Q. Phys) but I have a hard time believing in it, it feels counter-intuitive, but that doesn't mean anything. Nr 9 is Max Tegmark Level IV (https://space.mit.edu/home/tegmark/multiverse.pdf). There is also a philosophical theory called Modal Realism that states that everything that can possibly exist does exist. Nr 9 seems close to it, but I don't know if everything that can LOGICALLY exist equates to everything that can MATHEMATICALLY exist.

Not quite sure what you mean. Basis of mathematics is logic. Godel, Zorn, Russell and others shown that.

tbh they are all plausible and the simulated universe theory doesn't necessarily contradicts all the other possibilities

So you can vote all, that's why I left multiple choice options. I can give better explaination on each of those. I've took these categories from Brian Greene's book The Hidden Reality.

[Red Pill]

tbh they are all plausible and the simulated universe theory doesn't necessarily contradicts all the other possibilities

I would say that nr 9 makes simulated universes inevitable. However Paul Davies and some other physicists think that the hypothesis of a simulated universe is scientifically untenable. From this Davies concludes that multiverse theories are false.

[Red Pill]

Not quite sure what you mean. Basis of mathematics is logic. Godel, Zorn, Russell and others shown that.

Absolutely. My question was if there can be a universe or reality that is not mathematical but doesn't break the laws of formal logic.

[Hamilcar]

I would say that nr 9 makes simulated universes inevitable. However Paul Davies and some other physicists think that the hypothesis of a simulated universe is scientifically untenable. From this Davies concludes that multiverse theories are false.

what are his main arguments ?

[Red Pill]

what are his main arguments ?

If you take seriously the theory of all possible universes, including all possible variations," Davies said, "at least some of them must have intelligent civilizations with enough computing power to simulate entire fake worlds. Simulated universes are much cheaper to make than the real thing, and so the number of fake universes would proliferate and vastly outnumber the real ones. And assuming we're just typical observers, then we're overwhelmingly likely to find ourselves in a fake universe, not a real one."
So far it's the normal argument.
Then Davies makes his move. He claims that because the theoretical existence of multiple universes is based on the laws of physics in our universe, if this universe is simulated, then its laws of physics are also simulated, which would mean that this universe's physics is a fake. Therefore, Davies reasoned, "We cannot use the argument that the physics in our universe leads to multiple universes, because it also leads to a fake universe with fake physics." That undermines the whole argument that fundamental physics generates multiple universes, because the reasoning collapses in circularity.

https://www.space.com/30124-is-our-universe-a-fake.html

IMHO his argument is flawed because those civilizations could use the real physics of their universes to model a simulated universe. Of course they would also create simulated universes with different laws. But if we live in a simulated universe, we may just happen to live in one that is based on the same physics (or close enough) of its creators. It may also be that most universes where advanced civilizations able to create simulated universes exist have laws of physics similar to ours. So a "fake" universe doesn't necessary mean fake physics. What do you think?

[Hamilcar]

If you take seriously the theory of all possible universes, including all possible variations," Davies said, "at least some of them must have intelligent civilizations with enough computing power to simulate entire fake worlds. Simulated universes are much cheaper to make than the real thing, and so the number of fake universes would proliferate and vastly outnumber the real ones. And assuming we're just typical observers, then we're overwhelmingly likely to find ourselves in a fake universe, not a real one."
So far it's the normal argument.
Then Davies makes his move. He claims that because the theoretical existence of multiple universes is based on the laws of physics in our universe, if this universe is simulated, then its laws of physics are also simulated, which would mean that this universe's physics is a fake. Therefore, Davies reasoned, "We cannot use the argument that the physics in our universe leads to multiple universes, because it also leads to a fake universe with fake physics." That undermines the whole argument that fundamental physics generates multiple universes, because the reasoning collapses in circularity.

https://www.space.com/30124-is-our-universe-a-fake.html

IMHO his argument is flawed because those civilizations could use the real physics of their universes to model a simulated universe. Of course they would also create simulated universes with different laws. But if we live in a simulated universe, we may just happen to live in one that is based on the same physics (or close enough) of its creators. It may also be that most universes where advanced civilizations able to create simulated universes exist have laws of physics similar to ours. So a "fake" universe doesn't necessary mean fake physics. What do you think?

I think he overestimates the number of universes that bear intelligent civilizations because when you look at our universe the universal constants are so well adjusted that a tiny change would create a totally different universe and in most cases unviable ones. Of course there are other factors that imo don't necessarily lead to the creation of simulated universe so at the end the number of fake universes is probably lower than the real ones. And I agree with your last statement even though there is no way to know if we're in one with fake/real physics. Overall I find his arguments quite weak there are so many other possibilities and theories