This is extremely weak signal compared to understanding the technical argument, the literature is full of nonsense that checks all the superficial boxes. Unfortunately it’s not always feasible or worthwhile to understand the technical argument. This leaves the superficial clues, but you need to be aware how little they are worth.
Interesting coincident: Yesterday a new preprint appeared on the same topic
Quantum observers can communicate across multiverse branches Maria Violaris
It is commonly thought that observers in distinct branches of an Everettian multiverse cannot communicate without violating the linearity of quantum theory. Here we show a counterexample, demonstrating that inter-branch communication is in fact possible, entirely within standard quantum theory. We do this by considering a Wigner’s-friend scenario, where an observer (Wigner) can have quantum control over another observer (the friend). We present a thought experiment where the friend in superposition can receive a message written by a distinct copy of themselves in the multiverse, with the aid of Wigner. To maintain the unitarity of quantum theory, the observers must have no memory of the message that they sent. Our thought experiment challenges conventional wisdom regarding the ultimate limits of what is possible in an Everettian multiverse. It has a surprising potential application which involves using knowledge-creation paradoxes for testing Everettian quantum theory against single-world theories
This is extremely weak signal compared to understanding the technical argument, the literature is full of nonsense that checks all the superficial boxes. Unfortunately it’s not always feasible or worthwhile to understand the technical argument. This leaves the superficial clues, but you need to be aware how little they are worth.
Interesting coincident: Yesterday a new preprint appeared on the same topic
Quantum observers can communicate across multiverse branches
Maria Violaris
https://arxiv.org/abs/2601.08102
Scott Aronson already wrote in FB that it is wrong.