Self-reference problem in MWI (13yo amateur, be gentle)

[M4n90_L3m0n]

TL;DR

Proposes a 'pseudo-superposition' thought experiment where measuring a quantum system yields 'cake' or 'sofa.' Argues that since the observer is also in superposition, both outcomes must coherently coexist, creating a self-referential paradox rather than a standard quantum collapse.

Hi everyone! I'm a 13-year-old student from China. My English might be rough, and my physics knowledge is just amateur obsession, so please be gentle!

To reiterate: I'm a 13-year-old amateur, so my train of thought might have derailed a bit while writing this down. Please ignore any confusing parts! I promise the diagram on the left does a better job of explaining this "pseudo-superposition" mess than I do. Let's just look at the picture!

My core confusion is:

If all branches exist in the Multiverse, then the statement "MWI is correct" must also only be true in some branches, right? This feels self-referential.

Also, looking at the superposition of the cat (Sofa vs Cake), if there is no "conscious observer" (like a human) to ever check the box, does the superposition just stay forever? Would other universes even know what the "true" state is, or is reality just a consensus formed by redundant records?

I know I might be mixing up decoherence and information theory. Is there a paper or a term for this specific "self-reference" paradox in MWI?

Any help or even a good laugh is appreciated! Thanks!

P.S. – A quick note on how this post was written:

My English is really bad (think "I listening music" level), so I wrote the original version in Chinese, then used Google Translate + some light AI polishing to make it readable. If the tone sounds a bit robotic in places — that's why. But every single idea in this post is mine, I swear on my life (or at least on my cat's nine lives). I'm not here to spam or test AI-generated content. I'm genuinely stuck on this self-reference thing and want to learn from people who actually know what they're talking about.Not sure which prefix fits, so I picked one I thought matched. Bear with me, I'm a forum newbie!

Thanks for bearing with me.

 

[Nugatory]

If all branches exist in the Multiverse, then the statement "MWI is correct" must also only be true in some branches, right?

”All branches exist” isn’t quite right, it’s better to say that there is a branch for every possible outcome, but violating the laws of physics is not a possible outcome. There will be a branch in which a subatomic particle has randomly decayed and there will be a branch in which the particle has not decayed, but there will not be a branch in which the particle turns into a bird and flies away. So if MWI is a correct law of physics it will be true in all branches.

Also, looking at the superposition of the cat (Sofa vs Cake), if there is no "conscious observer" (like a human) to ever check the box, does the superposition just stay forever?

The conscious observer is irrelevant. Branching happens with decoherence happens, and a cat or a camera or pretty much any macroscopic object like a measuring device is complex enough to decohere. So we have two branches, the cat knows which one it is in, and the only reason we don’t is that we haven’t looked.
Decoherence is one of the really important advances in our understanding since Schrodinger proposed the cat thought exper and since Everett came up with what we now call MWI. There’s a good layman-friendly explanation, Lindley’s book “Where does the weirdness go”, but I don’t know if there’s a Chinese translation.