Pantheistic solipsism vs. Many World's Approach?

[Liger20]

Hello, I recently came across a wikipedia article entitled "pantheistic solipsism". I had never heard of this before, and when I read the article, it said that pantheistic solipsism is a concept that says that one can create a entirely different parallel universe simply by dreaming it up. When I first read it I thought, yeah right. But then I noticed that it provided a link to another wikipedia article on Everett's many world's interpretation of quantum mechanics. I thought about it for a while and realized that maybe it makes a certain degree of sense when looked at from a quantum mechanics standpoint. Of course, I could be completely wrong about that. Anyway, my questions for those of you who might be familiar with this bizarre concept are:

1. Is there any mathematical or scientific basis to this theory that could be explained in terms of Everett's ideas?

2. For a parallel universe to exist, does it necessarily have to obey the known laws of physics that we experience in our own universe, or it it subject to certain parameters?

I apologize if this these are bizarre questions, but quantum mechanics is bizarre, and I think that we should always consider every possibility open when we're dealing with the quantum realm.

 

[Coin]

The worlds that "split off" in the Everett-Wheeler multiverse aren't just "anything you can think of". The basic idea as I understand it is that the equations of quantum mechanics have places where instead of the equation giving just one single result for what happens next, it gives a probability distribution. One way to interpret this is to say that when this happens, the universe picks an item from the probability distribution "at random" (the copenhagen interpretation calls this "the collapse of the wave function"). The Many-Worlds "interpretation" looks at these same equations, but it interprets the meaning differently: Many-worlds simply assumes that every item in the probability distribution's ensemble actually exists as a parallel universe, and since from the perspective of an observer inside one of these universes the universe they're in is effectively "random" this makes it appear to the observer that the wavefunction collapsed randomly. Every single universe in this ensemble follows the exact same laws of physics because every single one is a valid solution to the equations of quantum physics; it's just that in a very small portion of these universes some very unlikely things (maybe even pathologically unlikely) have happened as the outcomes of quantum randomness.

If you want something closer to the idea you started with, look up Max Tegmark's ideas about the mathematical multiverse. Max Tegmark's idea is that every single universe that can be described by mathematics exists. However the Tegmark idea is not science, it is philosophy of science...