Reading this story inspired me to work through Joe Polchinski’s classic paper on the “Everett phone” [1]. The paper partially answers a question I’ve long had about Quantum Mechanics, what is so special about linearity? In a nutshell, the paper demonstrates that even the tiniest bit of nonlinearity (at least of a certain sort) would allow for communication between branches of the wavefunction, like in the Chiang story. Super deep stuff that, in my opinion, physics hasn’t even fully come to terms with.
[1] https://en.m.wiktionary.org/wiki/Everett-Wheeler_telephone